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Title: The anatomy of the frog
Author: Alexander Ecker
Translator: George Haslam
Release date: December 29, 2025 [eBook #77560]
Language: English
Original publication: Oxford: Clarendon Press, 1889
Credits: Thiers Halliwell, Brian Wilson, Bryan Ness and the Online Distributed Proofreading Team at https://www.pgdp.net (This file was produced from images generously made available by The Internet Archive/Canadian Libraries)
*** START OF THE PROJECT GUTENBERG EBOOK THE ANATOMY OF THE FROG ***
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‘pigment of the skin’
TRANSLATIONS
OF
FOREIGN BIOLOGICAL MEMOIRS
II
London
HENRY FROWDE
[Illustration]
Oxford University Press Warehouse
Amen Corner, E.C.
THE
ANATOMY OF THE FROG
BY
Dr. ALEXANDER ECKER
PROFESSOR OF HUMAN AND COMPARATIVE ANATOMY
IN THE UNIVERSITY OF FREIBURG
Translated, with numerous Annotations and Additions
BY
GEORGE HASLAM, M.D.
SCIENTIFIC ASSISTANT IN THE MEDICAL DEPARTMENT IN THE UNIVERSITY
OF ZÜRICH; FORMERLY ASSISTANT LECTURER IN PHYSIOLOGY IN THE
OWENS COLLEGE, VICTORIA UNIVERSITY, MANCHESTER
_ILLUSTRATED WITH MANY WOOD ENGRAVINGS_
_AND TWO COLOURED PLATES EXECUTED BY HOFMANN, WÜRTZBURG, BAVARIA_
Oxford
AT THE CLARENDON PRESS
1889
[_All rights reserved_]
TRANSLATOR’S PREFACE.
I undertook the publication of a translation of Ecker’s ‘Anatomie des
Frosches’ at the suggestion of Professor A. Gamgee while I was working
under his superintendence in the physiological laboratory of the Owens
College. The work was subsequently accepted by the Delegates of the
Clarendon Press, as one of the series of ‘Foreign Biological Memoirs,’
published by them. Early in the progress of the work it became evident
that a mere translation would be unsatisfactory, and that it would
be desirable to recast and modify several portions of the book. It
was deemed advisable to give greater completeness to the work by
descriptions of the minute structure of the several organs. For these
purposes the appearance of the work has been unavoidably delayed.
I have done my best to bring the book up to date by including the
results of recent researches, to which I have added many facts derived
from my own personal investigations. All such additions are enclosed
within square brackets [ ]. More than a hundred new figures, of which
one-third are original, have been added; and copious, though it is
feared still incomplete, lists of references to frog-literature have
been drawn up. By these additions the size of the book has been
considerably increased.
In the several sections into which the book is divided the following
points may be more particularly noticed:--
Sect. I. The Bones and Joints. The nomenclature of Parker and Bettany
has been adopted throughout.
Sect. II. The Muscles. This section remains in its original form.
Sect. III. The Nervous System. The chapters on the central
nervous system and the sympathetic system have been rewritten.
The description of the arteries of the brain is entirely new,
while the chapters on cranial and spinal nerves have received
many smaller additions, and have been rearranged to facilitate
reference.
Sect. IV. The Vascular System. The chapter on the heart is
practically new, and many additions and alterations have been made
in the descriptions of the blood-vessels and lymphatics.
Sect. V. The Alimentary Canal, with its appendages, the Spleen and
the Peritoneum. In this section much new material has been added:
the descriptions of the blood-vessels of the liver, the ducts
of the liver and pancreas, etc., being the results of original
investigation.
Sect. VI. The Respiratory Organs, the Thymus and Thyroid Glands.
These organs have been carefully studied and numerous new details
are noted. The lymphatic glands of the hyoid region have, after
some hesitation, been designated tonsils.
Sect. VII. The Urino-Genital Organs. A very large number of
preparations have been made to investigate the vessels and
uriniferous tubes of the kidneys; and the descriptions of the
remaining organs of this section have received large additions
from recent publications.
Sect. VIII. The Skin and the Sense-Organs. This section has, with the
exception of very small portions, been re-written and very much
enlarged.
Before concluding this preface, I must thank my friend Professor A.
Milnes Marshall, of the Owens College, for all the help and kindness
he has extended to me before and during the time this work has been
in hand; to him I am indebted not alone for the loan of books,
pamphlets, etc., and for much useful information, but also for the care
and patience with which he has read and corrected the whole of the
proof-sheets.
To Professor G. Lunge, of Zürich, I am indebted for the use of the
library of the Gesellschaft der Naturforscher of Zürich; and to my
friend Mr. C. Herbert Hurst, of the Owens College, for the drawings
for figures 132, 133, 134, and 136; also to Dr. Max Köppen, of
Strasburg, for the proof-sheets of his valuable paper, ‘Zur Anatomie
des Froschgehirns’: to these gentlemen I beg to express herewith my
heartiest thanks. Lastly, I must express my sense of indebtedness to
the Delegates of the Clarendon Press, who have kindly allowed me to
alter the original plan of the book, and to make extensive additions
far beyond the limits originally intended.
A second edition of the original German work is in course of
publication. The first part, on the bones and muscles, has already
appeared.
GEO. HASLAM.
Zürich, 1888.
PREFACE TO THE FIRST PART.
The idea of this manual on the anatomy of the frog, of which I now
offer the first part to physiologists and to those who would become
such, occurred to me during the preparation of the plates for my
‘Icones Physiologicae.’ I was then convinced of the necessity of such
a book. I regret that many direct and indirect causes have hindered
its earlier completion; fortunately, however, its appearance is still
opportune, as the need for the book has not diminished. I am conscious
that the book requires a recommendation to the indulgent judgment of
my fellow-workers, since almost every one has studied the frog for one
purpose or another, and each will closely criticize in that department
with which he is most familiar. Although I shall not be able to satisfy
all, still I hope that my work may serve as a useful basis for further
investigations, and I would apply to it the words with which Sömmering
prefaced his anatomy: ‘Ich wünschte ein Handbuch zu liefern und seine
Einrichtung so zu treffen, dass man künftig an ihm als einer Basis nach
Erforderniss leicht ändern, wegnehmen und zusetzen könnte[1].’
[Footnote 1: ‘I wished to furnish a manual so arranged that it might
serve as a basis easily altered, pruned, or enlarged as the future
might need.’]
Lest more be anticipated from the book than it is intended to supply,
I would observe that I have throughout had in mind only a descriptive
anatomy of the indigenous (German) frog; a comparative anatomy of
Batrachians was as foreign to my intention as were developmental
or histological questions: hence morphological details must not be
expected. Any hope of formulating a systematic nomenclature of the
muscles has been abandoned; as neither one based upon their mode of
action, of which we know so little, nor one based upon their origins
and insertions, as demonstrated by the unpronounceable names of
Chaussier and Dugès, is really practicable. I have therefore preferred
to avail myself, as far as possible, of the received names, which have
been chosen partly according to mode of action, partly according to
origin and insertion, and partly according to position and form; while
in the choice of new names I have given preference to the simplest.
The figures are, with few exceptions, original, and drawn by myself.
Their careful execution in woodcut has added a very necessary neatness
to that correctness, which alone I claim as mine.
ALEXANDER ECKER.
Freiburg,
_February, 1864_.
PREFACE TO THE SECOND PART.
Sixteen years have elapsed since the first portion of this anatomy of
the frog appeared; this second portion, therefore, requires a somewhat
apologetic introduction.
The nervous and vascular systems have, in substance, been known for
some years; still, certain points required a thorough revision: this
seemed especially necessary with regard to the cranial nerves. In
consequence of my anthropological investigations, and particularly
through undertaking the editorship of the ‘Archiv für Anthropologie,’
my attention was drawn into another channel, and I found it impossible
to work out this chapter: consequently the whole was deferred, and
would have been still longer delayed had I not received assistance.
At my request Professor Wiedersheim undertook to investigate afresh the
cranial nerves, the brain, the spinal cord, and the sympathetic system;
and the descriptions of these parts are the result of his work alone. I
regard it as most advantageous to this second part that so experienced
an investigator in the anatomy of Amphibia should have given me his
help.
The remaining portions appear almost unaltered as written several
years ago; and the majority of the illustrations date from the same
period. I had neither the time nor the zeal necessary to re-examine the
whole; besides, it is doubtful whether eyes some twenty years older
would improve matters.
This somewhat neglected book is therefore commended to the indulgence
of my fellow-workers, with the hope that it may at least form a basis
upon which further work may easily be done; to proffer more than this,
as I stated, with a quotation from Sömmering, in the preface to the
first part, I have never even hoped.
The final part of the work, on the viscera and sense-organs, has been
undertaken by Professor Wiedersheim, and will appear in the Spring of
1882.
ALEXANDER ECKER.
Freiburg,
_August, 1881_.
CONTENTS.
PAGE
INTRODUCTION 1
SECTION I. THE BONES AND JOINTS 11
" II. THE MUSCLES 53
" III. THE NERVOUS SYSTEM 121
" IV. THE VASCULAR SYSTEM 203
" V. THE ALIMENTARY TRACT WITH ITS APPENDAGES, THE
SPLEEN, AND THE PERITONEUM 267
" VI. THE LARYNX, LUNGS, VOCAL SACS, THYMUS AND THYROID
GLANDS, AND THE LYMPHATIC GLANDS (TONSILS?) OF
THE HYOID REGION 307
" VII. THE URINO-GENITAL SYSTEM, THE ADRENALS, AND THE
FAT-BODIES 325
" VIII. THE SKIN AND THE SENSE-ORGANS 351
ADDENDA, ETC. 425
INDEX 441
ILLUSTRATIONS.
FIGURE PAGE
1. The Green water-frog, _Rana esculenta_, L. 4
2. The Brown grass-frog, _Rana temporaria_, L. 8
3. Femur of _Rana esculenta_ 16
4. Vertebrae of do. 17
5. Vertebral column of do. 18
6, 7. Section through a vertebra of _Rana esculenta_ 20
8, 9. Urostyle of _Rana esculenta_ 21
10–14. Skull of do. 22, 23, 25, 28
15. Nasal Cartilages of frog 29
16, 17. Skull of _Rana esculenta_ 29, 30
18. Origin of suspensory cartilage from the skull 32
19, 20. Skull of _Rana esculenta_ 32, 33
21. Mandible of _Rana esculenta_ 34
22. Hyoid of _Rana esculenta_ 35
23. Omosternum of _Rana esculenta_ 36
24. Shoulder-girdle and sternum of do. 36
25. Shoulder-girdle of the frog 37
26, 27. Suprascapula of _Rana esculenta_ 38
28. Left scapula of _Rana esculenta_ 38
29. Scapula seen from behind 38
30. Left coracoid 39
31. Clavicle of the left side 39
32. Right shoulder-girdle of _Rana esculenta_ 40
33. Hinder border of the scapula and coracoid 40
34. Clavicular cartilage of _Rana esculenta_ 40
35. Humerus of _Rana esculenta_ (female) 41
36. Do. (male) 41
37. Do. (female) 41
38. Radio-ulnar of _Rana esculenta_ 43
39, 40. Bones of the forearm and hand of _Rana esculenta_ 44, 46
41, 42. Pelvis of _Rana esculenta_ 48
43. Horizontal section through the iliac bones, etc. 49
44. Femur of _Rana esculenta_ 49
45. Tibio-fibula of do. 50
46. Section of the tibio-fibula 50
47. Right foot of _Rana esculenta_ 51
48–50. Eye-muscles of do. 55, 56
51. Skull and orbital cavities of _Rana esculenta_ 57
52. M. levator bulbi of _Rana esculenta_ 57
53. Eye-muscles of _Rana esculenta_ 58
54. Facial muscles of do. 59
55. Muscles of the back and shoulder 60
56, 57. Muscles of the lower jaw of _Rana esculenta_ 61, 62
58. Muscles of the throat, chest, and abdomen of do. 63
59. Muscles of the hyoid bone and the tongue of do. 64
60. Do. (from below) 65
61. Do. (from right side) 66
62. Muscles of the throat, chest, and belly of _Rana esculenta_ 68
63. Muscles of trunk of _Rana esculenta_ (from the right side) 69
64. Second layer of abdominal muscles of _Rana esculenta_,
from right side and below 70
65. M. obliquus internus 71
66. Muscles of the back and shoulder blade 72
67. Muscles of the back and pelvic girdle of _Rana esculenta_ 74
68. Muscles of the shoulder, from below 77
69. Muscles of the right shoulder and upper arm 78
70. Right shoulder, from below 79
71. Muscles of the back and shoulder 79
72. Muscles of the chest, throat, and belly of _Rana esculenta_ 81
73. Muscle of right shoulder and upper arm 83
74. Muscles of the right arm of _Rana esculenta_ 84
75. Do. (deep layer) 85
76. Muscles of forearm of _Rana esculenta_ 86
77. Muscles of hand of _Rana esculenta_, volar surface 88
78. Second layer of muscles on volar surface of hand of
_Rana esculenta_ 88
79. Muscles of hand of _Rana esculenta_ 92
80. Muscles of left thigh of do. 95
81, 82. Do. (ventral surface) 98, 99
83. Deep muscles of left thigh of _Rana esculenta_ 100
84. Do. (Dorsal view) 101
85. Left half of pelvis of _Rana esculenta_ 101
86. Muscles of the right leg and foot of _Rana esculenta_
(Dorsal view) 103
87. Do. (seen from below) 105
88. Do. (Dorsal view) 106
89–91. Muscles of the plantar surface of foot of
_Rana esculenta_ 107, 111, 112
92–94. Dorsal view of muscles of foot of
_Rana esculenta_ 115, 117, 118
95. Pectoral region of _Rana esculenta_ 119
96. Hind portion of back and thigh of _Rana esculenta_ 120
97. The nervous system of _Rana esculenta_, from the
ventral surface 136
98. Dorsal view of brain of _Rana esculenta_ 143
99. Transverse section through hinder end of Medulla
oblongata 144
100. Do. at the point of origin of the abducens nerve 145
101. Do. of the auditory nerve 146
102. Ventral view of brain of _Rana esculenta_ 149
103. Lateral do. 150
104. Transverse section through the anterior portion of
the optic lobes opposite the origin of the
motor-oculi nerve. 151
105. Horizontal section through the brain to show the
ventricles 153
106. Section through the lower division of the pituitary body 157
107. Transverse section through the hinder portion of the
cerebral hemispheres 158
108. Transverse section near the middle of the cerebral
hemispheres 158
109. From a transverse section through one of the cerebral
hemispheres 159
110. Diagram to show the Vena spinalis posterior, etc. 164
111. Dorsal view of the orbit, etc. (deep dissection)
(_coloured_) Plate I.
112. Do. (superficial do.) (_coloured_) Plate I.
113. View of roof of mouth; mucous membrane, etc.
(_coloured_) Plate I.
114. Lateral dissection of head, etc. (_coloured_) Plate I.
115. Dissection of the floor of the mouth (_coloured_) Plate I.
116. Right half of skull of _Rana esculenta_ 174
117. The nervous system of _Rana esculenta_, from the
ventral surface 176
118. Ventral view of the brain and spinal cord, to show the
points of exit of the spinal nerves 178
119. Ventral view of the spinal ganglia 179
120. Schema of spinal ganglion 179
121. Dorsal branches of the spinal nerves 181
122. The brachial plexus 184
123, 124. Nerves of the ventral surface of the arm 185, 186
125. The N. radialis 186
126. Ventral view of the brain and spinal cord 188
127. The sciatic plexus 190
128. Distribution of the sciatic nerve 193
129. Nerves of the leg and sole of the foot 194
130. Distribution of the N. peroneus 196
131. Sympathetic cord 198
132. The heart and blood-vessels, seen from the ventral
surface 213
133. The heart, seen from above 214
134. The frog’s heart, seen from the ventral surface 215
135. Dissection of a case in which the auricular septum
is placed more to the left than is normal 215
136. Dissection of the heart from the left side 216
137 I. Transverse section through the junction of the hinder
and middle thirds of the ventricle of _R. temporaria_ 217
137 II. Transverse section through junction of the middle
and anterior thirds of the same heart 217
138. Portion of a transverse section through the middle
of the ventricle of _R. temporaria_ 218
139. Course of the cardiac nerves in the auricular septum 219
140. Group of nerve-cells on the cardiac nerve, from the
auricular septum 220
141_a_. Small group of nerve-cells from the auricular septum 221
141_b_. Isolated nerve-cells from frog’s heart 221
142. Arteries and veins of the Truncus arteriosus of _Bufo
vulgaris_ 222
143. Schema of the arterial system of _Rana esculenta_ 223
144. Right carotid gland 224
145. Arterial system of Rana esculenta 225
146. Transverse section at level of the larynx 226
147. Dissection to show the occipito-vertebral and the
cutaneous arteries 227
148. Branches of the occipito-vertebral and cutaneous
arteries in the head 228
149. Dissection to show the occipito-vertebral and the
cutaneous arteries 229
150. Subclavian artery of the left side 231
151. Arteries of the palmar surface of the hand 232
152. Arteries of the dorsal surface of the hand 232
153. Arterial system of _Rana esculenta_ 234
154. The urinogenital arteries 235
155. Bifurcation of the aorta and the iliac arteries 236
156. Arteries of the hinder extremity 237
157. Arteries of the dorsal surface of the foot 239
158. Arteries of the sole of the foot 240
159. Schema of the veins of _Rana esculenta_ 242
160. Distribution of the internal jugular vein and the
anterior portion of the cutaneous vein 243
161. The anterior caval vein and its branches 244
162. Course of the cutaneous vein as seen from the side 245
163. Veins in the region of the kidney 246
164. Veins of the liver 248
165. Veins of the hinder extremity 250
166. Transverse section of a septum with the attached skin 252
167. The sinus abdominalis lateralis 252
168. Sinus thoracicus transversus 253
169. The lymph-sacs of _Rana esculenta_ (seen from the
dorsal surface) 254
170. Do. (seen from the ventral do.) 256
171. Do. (seen from the side) 257
172. Transverse section through the trunk in the region
of the iliac lymph-sac 258
173. Dissection to show the iliac lymph-sac 259
174. Plan of attachments of the inferior femoral etc. septa 259
175. Transverse section of the thigh 260
176. The anterior lymph-hearts 261
177. The posterior lymph-hearts 261
178. The roof of the mouth 276
179. The floor of the mouth 277
180. The capillaries of the submucous layer (_coloured_) Plate II.
181 I. Transverse section of the premaxillary bone, to
show attachment of the teeth 279
181 II. Dentine and enamel 279
181 III. Enamel 279
182, 183. Muscles of the tongue 281, 282
184. The alimentary canal 283
185. The abdominal viscera of _Rana esculenta_ 284
186. Longitudinal folds of stomach of _Rana temporaria_ 285
187. The cells at the mouth of the gland of the fundus
of the stomach. (_coloured_) Plate II.
188. The mucous membrane of the pyloric end of the stomach
of _Rana esculenta_ 286
189. Mucous membrane of the pyloric end of stomach and
duodenum 288
190. Isolated fold of mucous membrane of small intestine of
_Rana temporaria_ 291
191. Fold of mucous membrane of _Rana temporaria_ 291
192. The large intestine of _Rana temporaria_ 292
193. Large intestine of _Rana esculenta_ 293
194. The liver 295
195. The pancreas and bile-canals 296
196 I. }
} The hepatic veins (_coloured_) Plate II.
196 II. }
196 III. The hepatic arteries (_coloured_) Plate II.
197. Liver-cells 299
198. The bile-capillaries 299
199. The pancreas and bile-canals 300
201. The peritoneum of _Rana esculenta_ 305
202. The position and relations of the larynx 311
203. The cartilaginous skeleton of the larynx 312
204. The larynx and surrounding parts 313
205. The muscles of the larynx 314
206. Three sections through the larynx of _Rana esculenta_ 316
207. The Rima glottidis 317
208. The lung of _Rana temporaria_ (_coloured_) Plate II.
209. The vocal sac of the right side 320
210. The thymus gland 321
211. The thymus gland of _Rana esculenta_ 321
212. The thyroid gland of _Rana esculenta_ 323
213. The lymphatic gland of _Rana esculenta_ 324
214. The male urino-genital organs 331
215. The right kidney 332
216. The blood vessels and lymphatics of the kidney 333
217. Vertical sections through the kidney (_coloured_) Plate II.
218. The uriniferous tubes 335
219. A gold preparation of the kidney of _Rana esculenta_
(_coloured_) Plate II.
220. Transverse section of the kidney 338
221. The bladder 339
222. The male reproductive organs 341
223. Various preparations from the testis 342
224. The female reproductive organs 344
225. Preparations from ovary and oviduct 346
226. The male urino-genital organs 348
227. The fat-body of _Rana esculenta_ 349
228. The epidermis from the head of _Rana esculenta_ 367
229. Vertical section through the skin of the back 368
230. Surface view of epidermis of _Rana temporaria_ 368
231. Nerve terminations of the branched pigment-cells of
the cutis 368
232. The temporary papillae in _Rana temporaria_ 371
233. The epidermis of the supplemental toe of
_Rana esculenta_ 375
234 I. Fore-foot of a male frog 375
234 II. The swelling on the supplemental toe of a male frog 375
235. The blood-vessels and lymphatics of the skin 376
236. Lateral sense-organ of tadpole of frog 378
237. Various parts from the fungiform papillae 381
238, 239. Frontal sections through the nose of two tadpoles 384
240 I A. Bowman’s glands _in situ_ from _Rana temporaria_ 386
240 I B. Section of Bowman’s gland 386
240 II. Vessels of nasal mucous membrane of _Rana esculenta_ 386
241. Separations from the olfactory mucous membrane of _Rana
temporaria_ 388
242. The tympanic membrane of _Rana esculenta_ 389
243. The columella 391
244. Antero-posterior section through the capsule of the
right labyrinth of _Rana esculenta_ 392
245. The membranous labyrinth of _Rana esculenta_ 394
246. Part of the outer wall of the perilymphatic space 395
247, 248. The right membranous labyrinth of _Rana esculenta_ 397
249, 250. The membranous labyrinth of _Rana esculenta_ 399, 401
251. Preparations from the ear of _Rana esculenta_ 402
252. The nerve-terminations in the membranous labyrinth of
_Rana esculenta_ 404
253. Endothelium from the inner surface of the sclerotic coat 406
254, 255. Preparation from cornea of _Rana esculenta_ 407, 408
256. The vessels of the choroid and iris 410
257. Fibres from the lens of the frog 414
258. Vertical section through retina of frog 415
259. Various preparations from the eye of the frog 417
260. The vessels of the vitreous body 421
261. Preparations from the nictitating membrane of _Rana
esculenta_ 423
INTRODUCTION.
There is no occasion, now-a-days, to offer a lengthened apology for
devoting a treatise solely to the anatomy of the frog, which enjoys
the doubtful honour of being, κατ' εξοχήν, the physiological domestic
animal. It is kept in every physiological laboratory, and is daily
sacrificed in numbers upon the altar of science. The physiologist has
recourse to it, not only to obtain answers to new questions, but for
the sake of demonstrating easily and quickly the most important known
facts of the science. These unlucky batrachians are to be had in any
number, and are specially adapted for experimental investigation: they
have consequently fallen under a harsher tyrant than the stork in the
fable, and their prophetic outcry in the frog-chorus of Aristophanes,
δεινὰ πεισόμεσbθα, has been literally fulfilled.
As the history of the most important physiological discoveries is
closely related with the employment of the frog in physiological
research, it will not be without interest to review briefly the history
of its use in scientific, especially in physiological, investigations,
and to record the services which it has already rendered to science.
Swammerdam (1637–1685), as du Bois-Reymond justly remarks, was the
first to make known the frog as an important means of research; he
says concerning it:--‘An den Thieren, die das heisseste Blut haben,
ist die Bewegung der Muskeln nicht so merklich oder hält vielmehr
nicht so lange an, als an Thieren die mit kälterem Blute begabt
sind. Dergleichen sind die Fische und viele andere Wasserthiere, wie
auch solche, die so wohl im Wasser als auf dem trocknen Lande leben
können. Deswegen habe ich insonderheit mit dem Frosch meine Versuche
angestellt. Denn an diesem Thiere sind die Sehnen sehr sichtbar und
lassen sich leicht entdecken und entblössen[2].’ Swammerdam made the
earliest experiments on the contraction of muscle by means of chemical
and mechanical stimulation of its nerves; thus laying the basis of our
present nerve and muscle physiology, which has been built up within
rather less than two hundred years; though during the first half of
this period but little advance was made.
[Footnote 2: ‘In animals with warm blood the action of the muscles is
neither so apparent nor so long continued as in those animals which
have cold blood, such as fishes and many other aquatic animals, and
those also which live both in water and on dry land. On this account I
have made my investigations chiefly on frogs, for in them the nerves
are very distinct, and are easily found and exposed.’ Buch der Natur,
Leipzig, 1752, p. 330.]
From the famous September evening of the year 1786, on which Galvani
first observed the twitchings of a frog’s leg suspended by a metallic
hook to an iron balcony, the frog has, down to the present time,
afforded almost the only material for the investigation of the
excitability of nerve and its associated electromotive changes,
and also no inconsiderable part of the remaining nerve and muscle
physiology. It was not until Müller devised the method of operating
on the frog that Bell’s law became capable of easy proof; and much
of our knowledge of the functions of the spinal cord is derived from
experiment upon it. Again, the muscles of frogs served, from the time
of Swammerdam to that of Eduard Weber and his followers, for the
investigation of the phenomena and the conditions of contraction;
and in almost all other branches of physiology there are important
doctrines which were first definitely established by experiment upon
the frog. But for the web of the foot of this animal (and the gills and
tail of its tadpole, in which Leeuwenhoek[3] describes the phenomena
most clearly) we should not, perhaps for a long time, have arrived
at a satisfactory knowledge of the existence and the conditions of
the capillary circulation. As is well known, an accurate acquaintance
with the constituents of the blood directly concerned in nutrition
has been obtained by observation on the frog, as well as important
facts in the physiology of the blood and lymph, such as the intimate
knowledge of the corpuscles of both fluids, and the coagulability
of the plasma; while in no less degree have experiments on these
animals served to establish the laws of the heart’s action. Moreover,
physiology is not the only science indebted to the frog: in histology
many important results have been obtained from observations on it, and
for histological instruction it is now indispensable. To it we owe much
of our knowledge of the structure of nerve fibres, their origin and
termination, especially in muscle, their relations within the ganglia,
and even the structure of muscular fibre itself. For the study of
reproduction and development the frog has, next to the chick, afforded
the most important material: one need but refer to the investigations
on impregnation from the time of Spallanzani to that of Newport[4], the
phenomena of cleavage, and many others.
[Footnote 3: Leeuwenhoek, Arcana Naturæ III, epist. 65 ad Reg. Soc.
Lond., p. 158.]
[Footnote 4: It may be well to remind the reader that this introduction
was written in 1864.]
Thus with progress of time the field in which the frog has been
submitted to observation and experiment, whether for the demonstration
of established facts to students or for the solving of new problems,
has vastly increased, and this batrachian has indeed become, as we have
stated, the physiologist’s domestic animal.
That, for these manifold uses, a more exact anatomical knowledge of
the frog is very necessary is self-evident. The majority of students
commencing the study of physiology have little more than a superficial
knowledge of the sciatic nerve and the leg-muscles; at most, of the
spinal cord and its nerve-roots; and only acquire any further knowledge
in a disconnected manner. For this they can scarcely be reproached,
the literature of the anatomy of the frog being so widely scattered in
monographs and journals that reference to it involves the expenditure
of much time. This attempt, therefore, to produce a complete anatomy
of the frog, based throughout upon my own observations, cannot be
considered superfluous; it is rather to be feared it may be thought
insufficient.
The European frogs[5] alone are treated of in the following
description, _i.e._ the two species, _Rana esculenta_, L., and _R.
temporaria_, L., the former being more particularly described, though
such differences in structure as occur are noted. This is not the place
to discuss the exact systematic characters of the two species, yet they
cannot be ignored entirely. The species were, from their habitats,
long ago distinguished by C. Gessner[6], and named _Rana rubeta_, _s.
gibbosa_, the garden or grass-frog, and _Rana aquatica_, _s. innoxia_,
the water-frog; at least, from his figure, the former can be no other
than _R. temporaria_, though Gessner, probably expecting to find in it
the _rubeta_ of older writers, adds that it ‘ist für giftig zu halten.’
[Footnote 5: For purposes of comparison other than European frogs
were examined, especially American species of _Rana_, for which I am
indebted to the kindness of my much esteemed friend Agassiz. These were
_Rana Catesbyana_, Shaw (_R. mugiens_, Catesby--_R. pipiens_, Harlan);
_R. sylvatica_, Leconte; _R. clamitans_, Daudin; _R. palustris_,
Leconte; _R. halecina_, Leconte. To these, however, no further
reference will be made in the text.]
[Footnote 6: C. Gessner, Thierbuch. Zürich. Fol., p. 157.]
Leeuwenhoek[7] also correctly distinguished between them, but it is to
Rösel[8] that we are chiefly indebted for a careful discrimination and
an accurate knowledge of the life-histories of the two species.
[Footnote 7: Leeuwenhoek, Arcana Naturæ, Vol. III of Ecker’s edition.
Leyden, 1722. Epist. 65 ad Reg. Soc. Lond., p. 154.]
[Footnote 8: Rösel, Naturgeschichte der Frösche Deutschlands, ed.
Schreber. Nürnberg, 1815, p. 36.]
[Illustration: Fig. 1.
The green water-frog, _Rana esculenta_ L.]
*Rana esculenta*, L. The green water-frog, Fig. 1, usually attains a
larger size[9] and is more active than the other species, and for this
reason is better adapted to the purposes of the physiologist; hence I
have chosen it for description.
[Footnote 9: The extreme sizes are much more pronounced in this
species. I have never found _R. temporaria_ of the size attained by
large specimens of the water-frog.]
The head is flat, as broad as it is long, and triangular with an
obtuse snout in front. The upper surface of the head, _i.e._ the space
between the eyes, is slightly concave, grooved, and narrower than in
_R. temporaria_. The tympanic membrane is circular, and relatively to
the eye is larger. The upper eyelids have several transverse folds in
their hinder part. The pupil is oval, with the long axis horizontal.
The vomerine teeth are arranged in two clusters, which are relatively
larger than in _R. temporaria_ and lie exactly between the posterior
nares, without however touching them. The openings of the Eustachian
tubes do not exceed in size the posterior nares to so great an extent
as they do in _R. temporaria_. The male possesses a vocal sac on
either side, which reaches the surface beneath the tympanic membrane
through a cleft placed behind the angle of the mouth, and is, in
well-developed specimens, about the size of a cherry. The hind limbs
are relatively longer. The toes are long, and taper towards their tips:
the webs between the toes are cut out semicircularly, and that of the
longest or fourth toe is continued to the tip of the last phalanx. The
supplemental toe is an oval prominence of cartilaginous hardness. The
skin of the back has wart-like tubercles arranged longitudinally in
raised lines; one of these lines runs on each side from the posterior
canthus as far as the thigh, and is very constant: in the male a second
line surrounds the posterior margin of the vocal sac; a corresponding
line exists in the female.
The skin of the belly is quite smooth, the colour presenting many
variations which appear to depend upon very diverse circumstances. It
varies with changes in the physiological condition of the animal. Von
Wittich[10] has shown that a bright green specimen changes to a dark
leafy green colour on exclusion of light; also, that dark specimens
become almost a lemon-yellow colour on exposure to bright sunlight;
and he has pointed out that this brightening of the skin is an active
condition dependent upon contraction of the stellate pigment-cells. It
is therefore not surprising, as the same inquirer observes, that one
should sometimes find specimens of _R. esculenta_ in which the ground
colour is almost a greenish yellow (as in Rösel’s figure, Pl. XIII),
whilst in others it can only be distinguished from the dorsal black
patches by a faint greenish shade. There is no doubt that difference
of habitat influences the colour; but this may again be modified by
light[11], as has been established in the case of fish by direct
observation[12]. Apparent varieties may this occur.
[Footnote 10: Von Wittich, Müller’s Archiv, 1854, p. 41.]
[Footnote 11: Lister, On the Cutaneous Pigmentary System of the Frog.
Phil. Trans., 1857, p. 627.]
[Footnote 12: Agassiz et Vogt, Histoire naturelle des poissons d’eau
douce (Neuchatel, 1839), Pl. IV, mention that the colour of trout is
very variable and that in shaded and deep-lying brooks and rivers a
variety is found which is black.]
In frog-tanks such diversities of colour may not unfrequently be
observed in the same individual, as for example when the lower part
of the body immersed in muddy water is dark, while the part above the
water is bright. That the process of casting the skin exercises an
influence on the brightness of the colouring is certain, yet there are,
as von Wittich has correctly remarked, other alterations of colour
which are in no way connected with this process, and are evidently
more of a pathological nature; such as when the frog assumes a dirty
green spotted appearance, the green fading more and more, until all
the patches which are usually green appear of a dirty greyish-brown
with a faint bronze shimmer. According to this author these changes are
most readily brought about by starvation. The dark colour which frogs
exhibit after hibernation is perhaps to be ascribed to the co-operation
of several of the causes mentioned above.
The usual colouring of healthy animals is as follows: the back is
bright green with three golden yellow longitudinal stripes, one median
and two lateral, and a number of irregular brown or black stripes of
approximately uniform width: on the head are a pair of black stripes
which pass from the angles of the eyes across the nares to the tip of
the nose; now and then the tympanic membrane and surrounding parts
have also a black patch, as in _R. temporaria_: another black stripe
is found on the anterior surface of the arm, in the region of the
shoulder: and on the thighs are black, yellow, and white mottlings.
The whole of the under-surface is white or yellowish. At times the
yellow stripes of the back are wanting or are indistinct. It has
already been mentioned that many varieties may occur; and these have
in all probability given rise to the descriptions of reputed new
species, such as _R. maritima_, Risso, found in South Europe; _R.
alpina_, Risso, found in the high-lying Alpine lakes; _R. hispanica_ of
Fitzinger and Bonaparte, and _R. calcarata_ of Michahelles, the last
three of which certainly cannot be retained. It is not improbable
that the water-frog, which Spallanzani[13] used in his experiments on
impregnation, was the _R. maritima_ of Risso. He says, one must not
confound his frog with that which Rösel calls the green water-frog;
the former being much smaller, without the three dorsal golden-yellow
stripes, and the spawning season (in Lombardy) occurring during April
and May. Rusconi[14] also describes two varieties in Northern Italy.
[Footnote 13: Spallanzani, Versuche über Erzeugung der Thiere and
Pflanzen. Leipzig, 1786, p. 5.]
[Footnote 14: Rusconi, Développ. de la Grenouille. Milan, 1826, p. 6.]
*Rana temporaria*, L., the brown or grass-frog, is so named from the
large black patch in the temporal region, _i.e._ between the eye and
the shoulder. While the separation of the preceding species into
several varieties does not seem to be well founded, it appears that two
distinct species have been included under the name of _R. temporaria_.
Millet of Angers[15] first described, in his Fauna du département de
Maine-et-Loire, as ‘grenouille rousse,’ a species differing from _R.
temporaria_, and gave the species previously known as _R. temporaria_
the name of _R. flaviventris_, ‘grenouille à ventre jaune.’ No further
notice, however, was taken of this observation, not even by Duméril and
Bibron in their ‘Erpétologie.’ Quite independently Steenstrup[16], in
the year 1846, pointed out that two frogs, differing in structure and
habits, had been confounded under the name _R. temporaria_; these he
distinguished as _R. platyrhinus_ and _R. oxyrhinus_. Von Siebold[17],
and also Schiff[18] in part, have confirmed these statements. My
own observations lead me to a like conclusion; I shall therefore
distinguish two species, viz.:--(1) _Rana temporaria_, L., _Rana
platyrhinus_, Steenstrup; (2) _Rana oxyrhinus_, Steenstrup.
[Footnote 15: Annales des Sciences naturelles. Zoologie, IV Série,
Vol. IV, 1855, p. 368.]
[Footnote 16: Amtl. Bericht über die 24. Versammlung deutscher
Naturforscher in Kiel, 1846, p. 141; Wiegmann’s Archiv, 1847, Vol. II,
p. 341; Steenstrup, Oversigt K. Danske Selsk. Forhandlgr., 1846, p. 92.]
[Footnote 17: Wiegmann’s Archiv, 1852, Vol. I, p. 14.]
[Footnote 18: Annales des Sciences naturelles. Zoologie, IV Série,
Vol. IV, 1885, p. 368.]
[Illustration: Fig. 2.
The brown grass-frog, _Rana temporaria_, L.]
*Rana temporaria*, L.; _Rana platyrhinus_, Steenstrup. The brown
grass-frog, Fig. 2, does not attain the dimensions of _R. esculenta_,
L., but is, however, always larger than _R. oxyrhinus_. The head is
somewhat broader than long, and the upper surface of the skull is not
grooved, as in _R. esculenta_, but is flat. The space between the
eyes is wider (according to Duméril, equal to the width of the upper
eyelid, whereas in _R. esculenta_ it is just two-thirds this width):
the fronto-parietal bones are wide and flat. The tympanic membrane,
in comparison with the eye, is smaller than in _R. esculenta_, and is
usually less distinguishable from the surrounding parts as regards
colour and transparency. The apertures of the Eustachian tubes are,
relatively to the posterior nares, larger than in the water-frog. The
vomerine teeth are comparatively small and lie in two groups placed
obliquely to each other, their anterior ends diverging from each other
and being prolonged as ridges to the anterior margins of the posterior
nares. The two groups do not lie between the nasal apertures, but
behind a line drawn transversely through their posterior margins. Vocal
sacs are absent in both sexes. The hind legs are relatively shorter:
the toes are not so evenly tapered off, indeed they are slightly
swollen: the fourth toe, as compared with the third and fifth, is
somewhat longer than in _R. esculenta_; the web of this toe does not
extend to the tip of the toe, but terminates in both sexes at the last
phalanx but one; the web on the third toe is less developed on the
thumb side than on the other: on the remaining toes also the margins
of the web are less developed than in _R. esculenta_, so that the
free borders appear more crescentic. The supplemental toe forms only
a soft and inconspicuous prominence. The back is mostly smooth; the
raised glandular ridge, which extends along each side from the eye to
the thigh, is present, but is much narrower and less prominent than in
_R. esculenta_; another ridge passes from the angle of the mouth to the
shoulder. The colouring in general, and especially the ground colour
of the dorsal surface, varies from the brightest tints to the darkest
brown-black; the conditions causing these variations being, no doubt,
the same as those described above in _R. esculenta_. A dark-brown
specimen taken from a dark frog-tank is usually yellowish red on the
following day. The black patch between the angle of the mouth and the
shoulder has given this species the name of _R. temporaria_, and is
constant. A black stripe passes from the eye across the nostril to
the tip of the snout, and a similar one is found upon the anterior
surface of the upper arm. On the hind legs the bands are chiefly
transverse. The ventral surface is yellowish, and sometimes spotted.
The thighs have a granular appearance, and these as well as the belly
and the neighbourhood of the anus have frequently a reddish coloration
presenting the appearance of an irritated surface.
*Rana oxyrhinus*, Steenstrup. This species is always smaller and more
elegant in shape than the preceding one. The head is conical, with
the pointed snout projecting beyond the lower jaw; a feature which is
especially evident on looking from below. The space between the eyes
is narrower than in _R. temporaria_, and is not grooved, but convex;
the fronto-parietal bones are narrow and arched. With respect to the
arrangement of the vomerine teeth and the sizes of the apertures of the
Eustachian tubes, this species holds an intermediate position between
the other two. Next to the pointed snout, the greatest difference
between this species and _R. temporaria_ is the presence of a much
larger supplemental toe, which is of cartilaginous hardness, compressed
from side to side, and contains a larger bone[19]. The vocal sacs
are absent. In the males the web of the longest toe reaches to the
last phalanx but one; in the females, on the contrary, the last three
phalanges project freely beyond the web. The extremities of the toes
are more pointed than in _R. temporaria_, in which respect, as also
in several others, it approaches _R. esculenta_. In colouring, _R.
oxyrhinus_ resembles _R. temporaria_; the throat, however, is usually
pure white, at least in the males, the breast dusky white and spotted,
while in _R. temporaria_ the throat and breast are more uniformly
coloured and yellowish. V. Siebold has remarked that, during the
pairing-season, the males are covered with a bluish bloom[20]; and, the
whole ground colour being bright at this period, very beautiful tints
result. V. Siebold[21] moreover states that the note which the males
produce during the pairing-season is different in the two species.
On the whole, _R. oxyrhinus_ appears to stand midway between _R.
esculenta_ and _R. temporaria_.
[Footnote 19: According to Steenstrup, _l. c._, the size of the
supplemental toe is in _R. temporaria_ one-half and in _R. oxyrhinus_
two-thirds of that of the next toe.]
[Footnote 20: I do not find, however, that this disappears when the
animals are on land; in fact I have animals before me in a glass in
which it is plainly seen.]
[Footnote 21: _l. c._, p. 15.]
Thomas[22], in addition, distinguishes another species, _R.
agilis_, which however may be the ‘grenouille rousse’ of Millet.
Schlotthauber[23] has described a frog which, in marking and colouring,
might hold a middle place between _R. esculenta_ and _R. temporaria_;
in my opinion this is probably a cross between the two. That attempts
at copulation are made, despite the difference of the pairing-season,
is well known; Pontallié[24] mentions this, and I have myself often
found males of _R. temporaria_ in conjunction with females of _R.
esculenta_.
[Footnote 22: Annales des Sciences naturelles. Zoologie, IV Série,
Vol. IV, 1855.]
[Footnote 23: Wiegmann’s Archiv, Vol. I, 1844, p. 255.]
[Footnote 24: Annales des Sciences naturelles. Zoologie, III Série,
Vol. XVIII, 1852, p. 243.]
* * * * *
I use the following terminology. I suppose the animal to be in its
natural position, the belly towards the ground, the back upwards; a
horizontal plane passing from the snout to the anus divides the body
into a superior or dorsal half and an inferior or ventral half. The
terms superior and inferior, dorsal and ventral, indicate positions
with relation to this plane. I call that part anterior which looks
towards the head, and that posterior which looks towards the anus. A
vertical plane at right angles to the middle of the longitudinal axis
of the body, divides it into an anterior or cephalic and a posterior
or caudal half. All sections and planes which lie parallel to this, as
well as this itself, are frontal. Lastly, by a perpendicular section
along the middle line of the body the animal is divided into right and
left halves; this plane is the median plane; and the position relative
to this plane is expressed by the terms median or lateral. Planes
parallel to the median plane are termed sagittal.
SECTION I.
THE BONES AND JOINTS.
THE BONES AND JOINTS.
LITERATURE.
*van Altena*, Commentatio ad quæst. zoologicam in academia
Lugduno-Batav. a. MDCCCXXVIII propositam, qua desideratur ut
systematice enumerentur species indigenæ reptilium ex ordine
batrachiorum addita unius saltem speciei anatomia et præsertim
osteographia accurata. Lugd. Bat. 1829. 4^o. With 4 Plates.
*Ange, Martin St.*, Recherches sur les organes transitoires des
batraciens. Annales des Sciences naturelles. 1^{re} Série.
Vol. XXIV. 1831.
*Bell*, Article Amphibia, in Todd’s Cyclopaedia of Anatomy and
Physiology. Vol. I, p. 90. 1835–1836.
*Born, Dr. Gustav*, Ue.d. Nasenholen u.d. Thränennasengang der
Amphibien. Leipzig, 1877.
*Bruch, G.*, Beiträge zur Naturgeschichte und Klassification der
nackten Amphibien. Würzburger Naturzeitschrift, 1862.
*Bruch, G.*, Neue Beobachtungen zur Naturgeschichte der einheimischen
Batrachier. Würzburger Naturzeitschrift, 1863.
*Cuvier*, Recherches sur les ossements fossiles. Vol. V. Pt. II.
Paris, 1825.
*Cuvier*, Leçons d’anatomie comparée. Paris, 1835. Vol. I.
*Cuvier*, Ueber die Rückenwirbel der Reptilien und Amphibien,
Froriep’s Notizen. Vol. XIII, p. 74. 1826.
*Daudin*, Histoire naturelle des Rainettes, Grenouilles et des
Crapauds. Paris, 1802.
*Ducrotay de Blainville*, Ostéographie ou description iconographique
comparée du squelette et du système dentaire des cinq classes
d’animaux vertébrés. Paris, 1841.
*Dugès*, Recherches sur l’ostéologie et la myologie des batraciens à
leurs différents âges. Paris, 1834. 4^o. With 20 Plates.
*Duméril et Bibron*, Erpétologie générale ou Histoire complète des
Reptiles. 1836.
*Gegenbaur*: 1. Ueber Bau und Entwicklung der Wirbelsäule bei
Amphibien überhaupt und beim Frosche insbesondere. Abhandlungen
der naturforschenden Gesellschaft zu Halle, Vol. VI. Halle, 1861.
2. Untersuchungen zur vergl. Anatomie der Wirbelsäule bei
Reptilien und Amphibien. Pt. I. Leipzig, 1862. (Carpus and
Tarsus.) With 4 Plates. 4^o.
*Gegenbaur*, Untersuchungen zur vergl. Anatomie der Wirbelthiere.
Pt. II. Schultergürtel. 1865.
*Günther*, Ueber geschlechtliche Differenzen in Knochen von lebenden
und fossilen Fröschen und Fischen. Annals of Natural History.
1859. Vol. III.
*Hallmann*, Die vergleichende Osteologie des Schläfenbeins, etc.
Hannover, 1837. 4^o. With 3 Plates.
*Hoffmann, C. K.*, Beiträge zur Erkenntniss des Beckens der Amphibien
und Reptilien. Leyden, 1876.
*Hoffmann, C. K.*, Bronn’s Klassen und Ordnungen des Thierreichs,
Vol. VI. Amphibien. Leipzig, 1873–8.
*Huxley*, On the Theory of the Vertebrate Skull; Croonian Lecture,
Proc. Royal Society, p. 381. 1858.
*Huxley*, Article Amphibia, Encyclopædia Britannica, IXth Edition.
1875.
*Huxley*, Lectures on the Elements of Comparative Anatomy.
*Huxley*, Handbuch der Anatomie der Wirbelthiere. Deutsche Ausg. von
T. Ratzel. 1873.
*Kehrer, G.*, Beiträge zur Kenntniss d. Carpus und Tarsus d.
Amphibien, Reptilien, und Säuger. Berichte d. naturf. Gesell. z.
Freiburg. 1886.
*v. Klein*, Beiträge zur Anatomie der ungeschwänzten Batrachier.
Jahres-Heft. Würtemberg, 1850.
*Köstlin*, Der Bau des knöchernen Kopfs. Stuttgart, 1844. 8^o.
*Leukart*, Zwischenkiefer. Valentins Repertoire. 1841, p. 155.
*Marshall, A. M.*, The Frog. Manchester and London. 2nd Edit., 1885,
pp. 45–59.
*Mayer, A. F.*, Beiträge zu einer anatomischen Monographie der Rana
pipa. Acad. Caes. Leop. Nov. Acta. 1825. Vol. XII, p. 527; and
Isis v. L. Oken. 1825. col. 317.
*Meckel*, System der vergleichenden Anatomie. II. Thl. I. Abthlg.
Halle, 1824. 8^o.
*Meckel*, Ueber das Zungenbein der Amphibien. Meckel’s Arch. f.
Physik. 1818. Vol. IV, p. 60.
*Mertens*, Anatomiæ batrachiorum prodromus sistens observationes
nonnullas in osteologiam batrachiorum nostratium. Halæ, 1820. 8^o.
*Mivart*, On the Classification of the Anurous Batrachians. Proc.
Zool. Soc. 1869.
*Morren*, Observations ostéologiques sur l’appareil costal des
batraciens. Bulletins de l’Acad. de Bruxelles, 1835, II.--Mémoires
de l’Académie, 1837. Tome X.
*Müller*, Beitrag zur Anat. d. Amph. Zeitschrift f. wissenschaftliche
Zoologie. Vol. IX. 1858, p. 178.
*Parker, W. K.*, Structure and Development of the skull of the common
frog. Phil. Trans. 1871, p. 137.
*Parker, W. K.*, Skull of Batrachia. Phil. Trans. 1876, p. 601.
*Parker, W. K.*, and *Bettany, G. T.*, Morphology of the Skull.
London, 1877.
*Pouchet*, Note sur les différences que le sexe imprime au squelette
des grenouilles. Comptes rendus. Vol. XXV, p. 761. 1847.
*Reichert, K. B.*, Vergleichende Entwicklungsgeschichte des Kopfs der
nackten Amphibien nebst den Bildungsgesetzen des Wirbelthierkopfs
im Allgemeinen und seinen hauptsächlichen Variationen durch die
einzelne Wirbelthier-Classe. Königsberg, 1838.
*Remak*, Untersuchungen über die Entwicklung der Wirbelthiere.
Berlin, 1855.
*Rösel, von Rosenhof*, Historia naturalis ranarum nostratium.
Nörnberg, 1758.
*Rudolphi and Breyer*, Observationes anatomicae circa fabricam Ranae
pipae. Berolini, 1811.
*Rusconi*, Développement de la grenouille commune. Milan, 1826.
*Rusconi*, Sulle metamorfosi delle osse della testa della rana.
Annali di Bologna. 1^{re} Série, Vol. II, p. 357.
*Schneider*, Historia amphibiorum. Jenae, 1799.
*Shaw*, General Zoology. London. Vol. II, Pt. I, p. 167.
*Stannius*, Zootomie der Amphibien (Handb. der Zootomie der
Wirbelthiere, 2. Buch). 2nd Edit. Berlin, 1856. 8^o.
*Stricker*, Untersuchungen über die Entwicklung des Kopfes der
Batrachier. Arch. f. Anat. u. Physiol. 1864, pp. 52–76.
*Stricker*, Beiträge zur Biologie der Batrachier. Verhandl. der
Wiener Akademie. 1866. Vol. XVI, pp. 451–456.
*Townson, R.*, Facts and Observations in Natural History. London,
1799.
*Troya*, Mémoire sur la structure singulière du tibia et du cubitus
des grenouilles et des crapauds. Mémoires de mathématique et de
physique présentées à l’acad. de Paris. Vol. IX. 1780.
*Wagner*, Icones Zootomicae. Leipzig, 1841.
*Wagner*, Lehrbuch der vergleichenden Anatomie. Leipzig, 1834–1835.
*Wiedersheim, R.*, Lehrbuch d. vergleichenden Anatomie der
Wirbelthiere auf Grundlage d. Entwickelungsgeschichte. Jena, 1886.
2nd Edit.
*Wiedersheim, R.*, Elements of Comparative Anatomy of Vertebrates,
translated by W. Newton Parker. London, 1886.
THE BONES AND JOINTS.
The consideration of the differences in form, number, and histological
structure, which the parts of the skeleton present during the various
stages of development does not fall within the scope of this book: we
have here but to deal with the adult frog.
The skeleton is made up of histologically different materials;
these are:--(1) bone, (2) hyaline cartilage, and (3) so-called
calcified cartilage. Concerning the last it is necessary to make some
observations. I have chosen for it the name calcified cartilage in
place of the more usual names ‘cartilaginous bone’ or ‘primordial
ossification,’ as by this term its nature appears to be expressed
without any ambiguity[25]: it is hyaline cartilage in which calcareous
particles have been deposited to a greater or less extent: in the fresh
state it has the appearance of moderately firm cartilage; when dry it
becomes opaque and white, like the calcareous crusts on the cartilages
of the Plagiostomata. The calcareous material is deposited in the
cartilage in finer or coarser granules; after removal of the lime by
means of acids, the cartilaginous structure becomes apparent although
not so perfectly as in unchanged cartilage.
[Footnote 25: Compare Müller, Zeit. f. wissen. Zoolog., Vol. IX.]
This calcified cartilage is widely distributed in the frog’s skeleton:
very many parts, which in higher animals consist only temporarily of
this substance during the transition from cartilage to bone, are in
the frog formed of it throughout life. It is especially well-marked
in the epiphyses of the long bones in the hand and foot, in the
bones of the shoulder-girdle, etc. To avoid repetition later on I
will briefly describe it as found in the first-mentioned situation.
Dugès[26] has described its external appearance, while Bruch[27] has
made us acquainted with its histological peculiarities. If a long
bone of the frog be dried, the femur for example, the middle part is
found to differ considerably from the epiphyses in colour and in other
particulars. The shaft alone has the appearance of bone, the epiphysis
consisting of a white, opaque, firm substance, resembling plaster of
Paris or lime, but which in the fresh moist state is exactly like
cartilage. The epiphyses, which are fitted to the ends of the diaphysis
like the cap of a stick-handle, have sharply defined margins (Fig. 3),
as is well seen in Figs. 36, 39, 45, and 46. If a section be made
through the epiphysis and part of the diaphysis, the long tube of true
bone is seen to cease abruptly above _o_, Fig. 3, and over the end of
it the epiphysis _E_ is fixed. This epiphysis consists almost entirely
of calcified cartilage _c′_, and has merely a superficial layer of
hyaline cartilage _A_. The bony cylinder of the diaphysis _o_, which
contains the marrow _M_ in its interior, is shut off from the epiphysis
by hyaline cartilage, the cells of which are arranged in transverse
layers, _o_.
[Footnote 26: Dugès, Recherches sur l’ostéologie et la myologie des
batraciens à leurs différents âges, p. 116.]
[Footnote 27: Bruch, Beiträge zur Entwicklungsgeschichte des
Knochensystems. Schweiz. Denkschriften, p. 118.]
[Illustration: Fig. 3.
Longitudinal section through the upper extremity of the femur of _Rana
esculenta_, magnified.
_A_ Hyaline cartilage (articular cartilage).
_c_ Hyaline cartilage closing end of bony cylinder.
_c′_ Calcified cartilage of epiphysis.
_D_ Bony cylinder of diaphysis.
_E_ Epiphysis.
_M_ Marrow cavity.
_o_ End of diaphysis.
]
I. THE VERTEBRAL COLUMN.
The _vertebral column_ of the frog consists of ten bones, _viz._ nine
true vertebrae, and the rod-shaped urostyle, which alone is almost as
long as all the remaining vertebrae.
I. GENERAL DESCRIPTION OF THE NINE VERTEBRAE.
*a.* The _bodies_ of the vertebrae are compressed from above downwards;
the posterior surface of each body, with the exception of the eighth,
presents an articular head covered with cartilage; the anterior
surfaces, with the exception of the ninth, present corresponding
articular depressions, covered with cartilage.
*b.* The _arches_, which have somewhat sharp margins both before and
behind, bear the following processes:-- *1.* The *articular processes*
(Figs. 4 and 5 _o o_) are similarly placed to those of the dorsal vertebrae
of man: they project horizontally, the cartilaginous articular surfaces
on the posterior processes being directed downwards, those on the
anterior upwards.
[Illustration: Fig. 4.
Vertebrae of _Rana esculenta_, seen from below, twice the natural size.
1 to 9 First to ninth vertebræ.
_c_ Urostyle.
_o o_ Articular processes.
_sc_ The two facets for articulation with the urostyle.
]
*2.* The *transverse processes* (Figs. 4 and 5 _t t′_) are strong,
flat, and of very varying size and direction. The transverse processes
of the fourth vertebra are the longest, those of the third only a
little shorter; the shortest are those of the seventh and eighth.
The atlas has no transverse processes. Those of the second and third
vertebrae project directly outwards and slightly downwards; those of
the fourth, fifth, and sixth upwards and backwards. The seventh and
eighth project more directly outwards and at the same time backwards;
the ninth upwards and markedly backwards. All the transverse processes
have cartilaginous epiphyses; the largest are those of the second,
third, fourth, and ninth vertebrae.
*3.* The *spinous processes* are generally small, but individually of
varying size, appearance, and direction. The longest are those of the
third, fourth, and fifth vertebrae; these are, in transverse section,
of a three-sided prismatic form, as in the dorsal vertebrae of man;
they are directed backwards and provided with cartilaginous epiphyses.
The spinous processes of the sixth and seventh are shorter, compressed
from side to side, project directly upwards, and are usually without
cartilaginous epiphyses; that of the eighth is still shorter. As
regards the spinous processes, those of the third, fourth, and fifth
vertebrae resemble those of the dorsal vertebrae in man; those of the
sixth, seventh, and eighth, lumbar vertebrae. The ninth has either
no spinous process or only a rudimentary one. The first and second
vertebrae may be looked upon as cervical vertebrae: the second has a
short spinous process with a cartilaginous epiphysis. In the first,
the cartilage which unites the two halves of the arch represents the
rudiment of a spinous process.
[Illustration: Fig. 5.
Vertebral column of _Rana esculenta_, from above, twice nat. size.
1 to 9 First to ninth vertebræ.
_c_ Urostyle.
_o o_ Articular processes.
_sc_ Facets for articulation with the urostyle.
_t t′_ Transverse processes.
]
II. DESCRIPTION OF PARTICULAR VERTEBRAE.
*1.* The *atlas* or *first vertebra* has a thin body, compressed from
above downwards, and an arch. The body has posteriorly a slightly
raised, cartilaginous, articular head, which is broader transversely:
in front it has two oval articular facets, which are separated from
each other by a median projection. Each facet is concave, and directed
forwards, outwards, and slightly upwards. The arch is completed above
by cartilage, which projects slightly to form the rudiment of a spinous
process. The hinder margin of the arch bears two articular processes.
Transverse processes are wanting.
*2.* The *second vertebra* presents all the general characters of an
ordinary vertebra, except that the transverse processes are directed
somewhat downwards.
*3.* The transverse processes of the *third vertebra* are longer than
those of the second: each is directed downwards, is broader at its
extremity than at its base, and bears a hammer-shaped cartilaginous
epiphysis larger than those of the remaining transverse processes.
*4.* The transverse processes of the *fourth vertebra* are the longest:
each is broader at its free end than at its base, is directed upwards
and backwards, and provided with a cartilaginous epiphysis.
*5*, *6*, *7*. The transverse processes of the *fifth*, *sixth*,
and *seventh vertebrae* are smaller, contracted towards their free
extremities, and directed upwards.
*8.* The *eighth vertebra* is distinguished from the rest by its body
possessing no articular head. It presents, at each end, a concave
articular depression. The transverse processes resemble those of the
seventh.
*9.* The *ninth vertebra* unites the vertebral column with the
hip-bones, and is hence to be regarded as a *sacrum*. The body bears on
its anterior surface an articular head for articulation with the eighth
vertebra: on its posterior surface are two small rounded and closely
approximated processes (Figs. 4 and 5 _sc_) for articulation with the
urostyle. The transverse processes are strong, broader at the free ends
than at their origin, directed upwards and backwards, and provided with
cartilaginous epiphyses.
III. ARTICULATIONS OF THE VERTEBRAE.
The articular heads and depressions of the vertebral bodies, together
with the joint surfaces of the articular processes, are covered with
hyaline cartilage. The periosteum of the bodies, as also that of
the articular processes, forms true capsular joint ligaments. The
articulations of the vertebrae are still further strengthened by
longitudinal fibres, which extend along the anterior and posterior
surfaces of the vertebrae, and correspond to the _ligamentum vertebrale
commune anticum et posticum_ of man. Between the vertebral arches are
membranes which represent the _ligamenta intercruralia_. Between the
spinous processes are bands of connective tissue which form _ligamenta
interspinalia_. (For the articulation of the atlas with the occiput,
see page 24.)
IV. STRUCTURE OF THE VERTEBRAE[28] (Figs. 6 and 7).
[Footnote 28: Cf. Gegenbaur, (1) Über Bau u. Entwicklung der
Wirbelsäule bei Amphibien überhaupt u. beim Frosch insbesondere.
Abhand. d. Naturforsch. Gesell. zu Halle, vol. vi, 1861; (2)
Untersuch. zur vergleich. Anat. d. Wirbelsäule bei Amphibien u. Rept.,
Leipzig, 1862. As regards the adult animal I can bear out Gegenbaur’s
observations. The scope and limits of this book forbid me to go further
into the developmental history.]
[Illustration: Fig. 6.
Transverse section through a vertebra of _Rana esculenta_, magnified.
_c_ Cancellous bone.
_Ch_ Chorda dorsalis.
_Ch′_ Sheath of chorda dorsalis.
_o_ Compact bone on the upper and lower surfaces of the body.
]
Each vertebral body consists of a cylinder of compact bone, which is
directly continued into the bony substance of the arch. In the interior
of the cylinder is found an isolated persistent vestige of the _chorda
dorsalis_ (_Ch_): this is surrounded by cancellous bone (_c_), which
extends backwards towards the articular head and forwards directly into
the articular cartilage, compact bone being absent in these parts. In
a transverse section of a vertebral body the following parts are seen
(Fig. 6):--*a.* An outer layer of compact bone (_o_) (the transverse
section of the above-mentioned cylinder), which is formed of parallel
lamellae of varying thickness. These, according to Gegenbaur, and as
I can confirm, are arranged in well-defined groups, each of five to
eight lamellae. The number of the secondary lamellae increases with the
age of the animal. *b.* In the interior, in the form of a cylinder, is
the remnant of the _chorda dorsalis_. It consists of a double sheath
(_Ch′_) and contents (_Ch_) composed of chorda-cells. *c.* Immediately
around the persistent portion of the chorda lies the central part of
the vertebral body, formed by transformation of the vertebral cartilage
and of the bases of the original cartilaginous arches. At each side of
the _chorda_ are large marrow-spaces (_c_), filled with cells, from
which proceed narrower canals, winding in various directions, and
anastomosing freely with one another both before and behind. Their
walls are constituted partly of true bone, partly of cartilage.
[Illustration: Fig. 7.
Longitudinal section through the posterior half of the body of a
vertebra of _Rana esculenta_.
_a_ Cartilage of the head.
_c_ Cancellous bone.
_o_ Shell of compact bone.
]
V. THE UROSTYLE (Figs. 8 and 9).
The *urostyle* is a long, median, rod-like bone, which projects
backwards, midway between the two hip-bones, and terminates over the
anus. The anterior end (Fig. 8 _a_) is the thicker and broader part of
the bone, and has two articular depressions (Fig. 9) for articulation
with the two facets of the ninth vertebra. The hinder end is pointed
and cylindrical, and terminates in a cartilage, which is fixed in the
tubular end of the bone. The middle portion is almost cylindrical, and
has a groove along the ventral surface which gradually becomes less
marked behind. The dorsal surface bears a ridge (Figs. 8 and 9 _s_),
which is high and thick in front, becomes sharper and less prominent
as it proceeds backwards, and gradually disappears towards the
hinder third of the bone, so that in transverse section the anterior
two-thirds of the bone appear triangular, with a ventral and two
lateral surfaces: while the hinder third is cylindrical. The anterior
portion of the bone contains a canal, _canalis vertebralis_ (Fig. 9
_c.v._), which is a continuation of the vertebral canal, along which
the hindermost spinal nerves pass. On each side of the anterior portion
of the urostyle are small apertures (Fig. 8 _c.c._), which lead into
canals (_canales coccygei_), which open into the vertebral canal, and
through which the coccygeal nerves pass. In front of these openings
and partly overhanging them are small triangular projections (Fig. 8)
(_processus transversarii_): these, however, are not constant, and are
more often found in _R. esculenta_ than in _R. temporaria_, in which
latter species the openings are smaller.
[Illustration: Fig. 9.
Urostyle of _Rana esculenta_, seen from the side, twice nat. size.
_c_ Ventral border.
_c.v._ Canal. vertebralis.
_s_ Dorsal ridge (pr. spinos.).
]
[Illustration: Fig. 8.
Urostyle of _Rana esculenta_, seen from the side, twice nat. size.
A bristle is passed through the _canal. vert._ and out through the
_canal. coccyg._ of the right side.
_a_ Anterior extremity.
_c.c._ Canal. coccyg.
_s_ Dorsal ridge (pr. spinos.).
]
II. THE SKULL.
The flat form of the frog’s head, as in batrachians generally, depends
upon the wide separation of the jaw-bones of the two sides, and on the
large size of the orbital cavities and the horizontal direction of
their floors. The outer circumference of the head forms a parabolic
frame (Figs. 10 and 11), composed of the maxillary (_m_), premaxillary
(_i_), and quadratojugal bones (_j_). In the middle of this curved
framework lies the elongated prismatic cranium. Anteriorly, this is
attached to the fore-part of the frame by means of the cartilaginous
skeleton of the organs of smell (Fig. 11 _e′_); posteriorly, it
widens out into two transverse arms (_p_), which contain the organs
of hearing. From this base, on either side, a bony strut, composed
of the posterior arms of the squamosal (_t′_) and of the pterygoid
bones, passes backwards to the hinder end of the frame. The anterior
arm of the squamosal bone (_t_) does not quite reach the framework,
but is attached to it by ligament alone. Between the last-named
arm posteriorly, the cranium on the inner side, and the maxillary
frame-work laterally, is a large space representing the orbital and
temporal fossae of human anatomy.
[Illustration: Fig. 10.
Skull of _Rana esculenta_, seen from above, twice natural size.
_e_ Sphenethmoid.
_fn_ Nasal.
_f.p._ Fronto-parietal.
_i_ Premaxillary.
_j_ Quadrato-jugal.
_m_ Maxillary.
_o_ Exoccipital.
_op_ Opisthotic.
_p_ Prootic.
_pt_ Pterygoid.
_pt′_ Posterior limb of pterygoid.
_t_ Squamosal.
_t′_ Posterior arm of the same.
]
[Illustration: Fig. 11.
Skull of _Rana esculenta_, seen from below, twice natural size.
_c_ Cartilaginous wall of skull.
_e_ Sphenethmoid.
_e′_ Cartilaginous skeleton of nose.
_h′_ Stylo-hyoid.
_i_ Premaxillary.
_m_ Maxillary.
_m′_ Quadrate tract.
_o_ Exoccipital.
_p_ Prootic.
_p′_ Anterior arm of prootic (_ala magna_ autt.).
_p″_ Trigeminal foramen.
_pl_ Palatine.
_pt_ Pterygoid.
_pt′_ Posterior arm of pterygoid.
_s_ Parasphenoid.
_v_ Vomer.
]
A. THE CRANIUM.
The cranium of the frog is a prismatic tube, wide behind, narrow in
front, and formed in great part of cartilage (Figs. 15 and 17). Our
indigenous species are characteristically distinguished from one
another by peculiarities in the form of the cranium. In _R. esculenta_
it is long and narrow, in _R. temporaria_ short and wide. The superior
surface in the former is markedly concave, while in the latter it is
flat, and in _R. oxyrhinus_ arched. These differences are readily
recognised in the living animal.
*The Bones of the Cranium.*
*1.* The *exoccipital bones*, _ossa occipitalia lateralia_, Cuvier
(Figs. 10, 11, 12, 14, 16 _o_).
*Cuvier*, _l. c._, p. 387, Pl. XXIV, bb.--*Dugès*, _l. c._, n.
14.--*Parker* and *Bettany*, _l. c._, p. 166, exoccipitals.
[Illustration: Fig. 12.
Skull of _Rana esculenta_, seen from behind, twice natural size.
_a_ Stapes.
_a′_ Columella auris.
_a″_ Extrastapedial.
_c_ Condyles of exoccipitals.
_h_ Stylo-hyoid.
_o_ Exoccipitals.
_p_ Prootic.
_p′_ Process to which the jaw is attached.
_t_ Squamosal.
]
These paired bones form the hinder part of the cranium; they bound the
_foramen magnum_, and articulate with the vertebral column. They are
imbedded in the cartilaginous matrix of the skull, and are separated
above by an unossified part of this matrix (_occipitale superius_,
Dugès), which represents the tabular portion of human anatomy: below
they are separated by a similar part (_occipitale basilare_, Dugès)
which represents the body of the occipital bone. They therefore
properly represent only the condylar portions (_partes condyloideae_)
of the human occipital bone. Each possesses a cartilaginous articular
head, for articulation with the first vertebra: these converge below,
and surround the lower half of the circumference of the _foramen
magnum_. This latter has, in _R. esculenta_, a transversely oval
outline; in _R. temporaria_, a somewhat heart-shaped outline, with
the apex directed upwards: in accordance with this the whole bone is
wider than high in the first species; and in the latter it is higher
than it is wide. From the upper and outer border of the _foramen
magnum_ on each side a ridge runs obliquely outwards and downwards,
in which lies the suture between this bone and the prootic bones. This
bony ridge (_processus mastoideus_, autt.) is usually cartilaginous
in _R. esculenta_, even in old animals; in _R. temporaria_, even in
young specimens, it is bony. In the latter species the bones unite
very early, while in the former they remain separated by the primitive
cartilage. Between this crest and the _processus condyloideus_
there is a depression (_fossa condyloidea_), with a hole (_foramen
condyloideum_) through which the vagus nerve leaves the cranium. The
exoccipital take part in the formation of the labyrinth of the ear, as
will be noticed later on.
_Articulation of the Exoccipital Bones with the Atlas._ From the middle
of the anterior surface of the body of the atlas a ligament arises,
representing to a certain extent the _lig. suspensorium dentis_, and
attached to the basal portions of the exoccipital bones.
*2.* The *prootic bones*, _ossa petrosa_, Cuvier (Figs. 10, 11, and
12 _p_).
*Cuvier*, rocher, _l. c._, p. 388, Pl. XXIV, ee.--*Dugès*, n. 12,
rupéo-ptéréal.--*Stannius*, ala temporalis.--*Meckel*, Schädelstück
des Schläfenbeins.--*Parker* and *Bettany*, _l. c._, prootic.
These paired bones lie at the sides and in front of the exoccipital
bones. As already explained, they remain in _R. esculenta_ separated
from these by cartilage, while in _R. temporaria_ they early enter
into bony union with them; this is due to the complete ossification
of the _processus mastoideus_ in the latter species, as stated above.
The prootics form the lateral expansions of the posterior part of the
skull in which the organs of hearing are placed. The large cavity which
contains the ear labyrinth is completed by the exoccipital: internally
it opens freely into the skull, and externally on the posterior wall
of the skull through the _foramen ovale_, which is formed by both
these bones. The postero-lateral part of the prootic usually remains
cartilaginous: at the side and in front of the _foramen ovale_ this
cartilage is pierced by a small opening, through which passes the
_nervus facialis_ or _ramus tympanicus n. vagi_ (Volkmann). At the
side there is a process to which the suspensorium of the lower jaw is
attached (Fig. 12 _p_): behind this is a hollow in which the auditory
ossicles lie, and which may be designated _fossa tympanica_ (Fig. 12
_t_). The anterior border of the bone forms the hinder and inner
walls of the orbit. Here also is the trigeminal foramen (Fig. 11
_p″_) through which the _N. trigeminus_ and the several nerves for
the muscles of the eye pass; it represents the _foramen ovale_, _for.
rotundum_, and the _fissura orbitalis superior_ (sphenoidal fissure) of
the human sphenoid bone. The foramen is sometimes, especially in young
animals, only a notch, which is completed by cartilage. On account of
the relation of this part (Fig. 11 _p′_) of the bone to the nerves
which pierce it, the whole bone has been named by Stannius the _ala
magna_ or _temporalis_ of the sphenoid; it has been also looked upon as
a bone which contains these elements, as by Dugès, who on this account
calls it rupéo-ptéréal.
[Illustration: Fig. 13.
Skull of _Rana esculenta_, seen from below, twice natural size.
_c_ Cartilaginous wall of skull.
_e_ Sphenethmoid.
_e′_ Cartilaginous nasal skeleton.
_h′_ Stylo-hyoid.
_i_ Premaxillary.
_m_ Maxillary.
_m′_ Quadrate tract.
_o_ Exoccipital.
_p_ Prootic.
_p′_ Anterior arm of prootic.
_p″_ Trigeminal foramen.
_pl_ Palatine.
_pt_ Anterior arm of pterygoid.
_pt′_ Posterior arm of pterygoid.
_s_ Parasphenoid.
_v_ Vomer.
]
_Appendages of the Prootic Bones._
1. The *styloid cartilage*. From the cartilaginous portion of the
prootic the styloid cartilage runs downwards, backwards, and inwards,
and is continued directly into the anterior cornu of the hyoid bone
(Figs. 11 _h′_ and 12 _h_).
2. The *auditory ossicles*.
_a._ A thick cartilaginous disc, the _operculum_ (Fig. 12 _a_),
closes the _foramen ovale_.
_b._ To the operculum is attached a bony, club-shaped piece, the
_columella auris_ (Fig. 12 _a′_), which has at its inner, thicker end
a cartilaginous epiphysis, the *interstapedial*; it lies transversely
with the apex directed outwards, and this longer portion is the
*mediostapedial*.
_c._ To the apex of the mediostapedial is attached, at an obtuse
angle, the third cartilaginous piece, the *extrastapedial* (Fig. 12
_a″_). It is attached to the tympanic membrane, and by its upper
portion is fastened to the cartilaginous tympanic ring by a smaller
piece, the *suprastapedial*.
3. The *tympanic ring* (_annulus tympanicus_) is an annular
cartilaginous frame; or more exactly, has the shape of a short,
truncated cone, as it narrows towards the middle line: it is attached
to the squamosal bone. (See Organ of hearing.)
*3.* The *parasphenoid*, _os sphenoideum_, Cuvier (Figs. 11 and 16
_s_).
*Cuvier*, _l. c._, p. 388, Pl. XXIV, d.--*Dugès*, n. 8.--*Meckel*,
Theil des Grundbeins.--*Parker* and *Bettany*, _l. c._,
parasphenoid.
A large portion of the base of the cranium is taken up by this
cruciform bone. Of the two longitudinal median processes, the
posterior is by far the shorter, and lies in front of and partly
below the cartilaginous _os occipitale basilare_. The anterior longer
longitudinal arm closes in the greater part of the cranium from below,
and articulates by its outer edges with that part of the prootic bones
often described as the _alae magnae_, and also with the cartilage
lying in front, which forms the greater part of the lateral walls of
the cranium. The anterior extremity of the bone articulates with the
palatine bones. The transverse arms lie on the under surface of the
exoccipitals and of the prootics.
The greater width of the cranium in _R. temporaria_ is associated with
the greater relative width of the anterior arm of this bone.
4. The *fronto-parietal bones*, _ossa fronto-parietalia_, Cuvier
(Figs. 10 and 14 _fp_).
*Cuvier*, _l. c._, p. 387, Pl. XXIV, c. c.--*Dugès*, n.
1.--*Parker* and *Bettany*, _l. c._, fronto-parietal.
These are a pair of somewhat long, flat bones, which form the principal
part of the upper wall or roof of the cranium, and cover in superiorly
the cartilaginous cranium, which is here, in great part, persistent.
They are united in the middle line by the sagittal suture; posteriorly
they articulate with the exoccipital and prootic bones; anteriorly with
the sphenethmoid, which they overlap like tiles. The outer margin of
each bone is bent somewhat downwards (Fig. 16 _fp_), and between it and
the parasphenoid there is a space in the wall of the cranium which is
closed in by cartilage and connective tissue only.
These bones are narrower in _R. esculenta_, and along the sagittal
suture are depressed into a groove: where the superior surface bends
down to become lateral the edges are much more prominent. In _R.
temporaria_ the bones are broader and flat or even somewhat arched. The
latter condition is still more marked in _R. oxyrhinus_.
*5.* The *sphenethmoid*, _os ethmoideum_ (Figs. 10, 11, 14, and 16
_e_).
*Cuvier*, os en ceinture, _l. c._, p. 387, Pl. XXIV, a.--*Dugès*,
n. 15.--*Rathke*, anterior or sphenoidal wing (Vortr. z. vergl.
Anat. d. Wirbelthiere, Leipzig, 1862, p. 42).--*Meckel*, Riechbein,
_l. c._, p. 502.--*Parker* and *Bettany*, _l. c._, ethmoid.
The long tubular cranium is completed anteriorly by a single bone,
which forms at once the roof, floor, and lateral walls. It is
consequently more or less ring-shaped, on which account it has been
named ‘os en ceinture’ by Cuvier. Only the posterior portion is
annular, however: the anterior portion forms a double canal, with a
median partition, for the passage of the nerves of smell, and as these
canals are widened out anteriorly, this part of the bone helps to
complete the nasal cavities, which, however, are bounded for the most
part by cartilage, as described below. In some species of frogs (as for
example _R. occellata_, Rathke) this cartilage is partly ossified.
The sphenethmoid has on each side a small bony canal, running forwards
and inwards, through which the _ramus nasalis_ of the first division of
the trigeminal nerve passes.
The *cartilaginous skeleton of the nose* (Figs. 14 and 16 _n_, _n″_,
_n‴_, _n⁗_). The anterior borders of the funnel-shaped cavities of
the sphenethmoid pass into cartilage, which forms two capsules,
separated from each other by a median cartilaginous septum, and opening
laterally. We can distinguish, (_a_) a cartilaginous septum, forming
a continuation of the bony one; (_b_) the floor of the nasal cavity,
narrower behind, wider in front; (_c_) a roof somewhat narrower
than the floor. The floor and roof are united in front by an arched
surface. From this cartilaginous capsule various processes project,
which unite it to other portions of the facial skeleton: firstly, from
the most posterior portion of the capsule there passes transversely
outwards a bar of cartilage (_sn_), which, widening, becomes continuous
with the cartilage (_sp″_) forming the basis of the anterior arm of
the pterygoid bone. From the anterior angle a cartilaginous process
passes outwards (Figs. 14, 16 _n″_), which is attached to a projection
on the anterior end of the maxillary bone; from the same spot a
horn-shaped cartilaginous process (_n″_, _n‴_) curves round backwards
and towards the middle line. This projection bounds the nasal cavity
externally, sending off a free process (_n‴_) on the way, and ends with
a double point on the roof of the cartilaginous nasal cavity (_n⁗_).
On the floor of the nasal capsule, on either side, is a knob-shaped
cartilaginous eminence, running from behind, forwards and outwards;
this may be regarded as an indication of a turbinated bone. From the
anterior wall there passes into each nasal cavity an almost horizontal,
partly ossified plate (_c.n._), ending posteriorly in a free pointed
border. These are the _cornets_ of Dugès (_l. c._, p. 12, Pl. I,
Figs. 1, 5), who correctly regarded them as turbinated bones. Cuvier
described them as rudimentary nasal bones[29].
[Footnote 29: Cuvier (Ossem. fossil., V, 2. 388) says that these little
bones are fixed outside the nasal cavity, so that we may suppose that
he confounded them with the nasal cartilages found in this situation.
Dugès correctly indicates their position to be inside of the nasal
capsule. Meckel (Vergl. Anat. II, 504) also regards them as nasal
bones. Bruch (Würzb. naturwiss. Zeitschrift, vol. II, 1861, p. 213)
could not find them in any frog-skull, doubtless because he did not
look inside the nasal capsules.]
[Illustration: Fig. 14.
Cartilaginous basis of the skull of _Rana esculenta_, from above, twice
natural size. Cartilage shown by stippling.
_a.n._ Wings of nasal cartilage.
_c.n._ Concha narium.
_e_ Sphenethmoid.
_ff′_ Foramina of cranium.
_fn_ Nasal.
_fp_ Fronto-parietal.
_i_ Premaxillary.
_j_ Quadrato-jugal.
_m_ Maxillary.
_n_, _sn_ Cartilaginous nasal skeleton.
_n′_, _n″_, _n‴_ Processes of the cartilage.
_o_ Exoccipital bones.
_p_. Prootic.
_pt_ Anterior arm of pterygoid.
_pt′_ Posterior arm of pterygoid.
_s′_ Cartilaginous cranium.
_sp_ Cartilage of suspensorium.
_sp′_ Cartilage under the squamosal.
_sp″_ Cartilage under the pterygoid.
_t_^1 Anterior }
_t_^2 Middle } arm of the squamosal.
_t_^3 Posterior }
]
The alar cartilages of the nose have still to be described. They are
(_a.n._) shell-shaped cartilages, hollowed out on the inner sides and
decreasing in width from before backwards. They are movably attached
by their anterior broader ends to the tips of the projecting portions
of the premaxillary bones, and are so arranged as to bound the lateral
margins of the nasal apertures, which they overlap.
[Illustration: Fig. 15.
Nasal cartilages of frog, front view.
_an_ Concha narium.
_i_ Premaxillary bones.
_i′_ Ascending process of same.
_m_ Upper jaw.
_m′_ Lower jaw.
_n_ Olfactory capsule.
]
*6.* The *cartilaginous basis of the skull*, _Primordial cranium_
(Figs. 14, 16).
*a.* If the fronto-parietals be removed, (Figs. 14, 16), a cartilage
(_s′_) is found which partially closes the cranial cavity, and which is
usually perforated on either side by a foramen (_f′_). More anteriorly
in the median line is found a space (_f_) which extends to the
sphenethmoid bone, and is only closed by connective tissue: posteriorly
the cartilage extends between the exoccipitals as far as the _foramen
magnum_, representing the _os occipitale superius_.
*b.* The base of the cranium is (Fig. 16) also partly cartilaginous. If
the parasphenoid (_s_) be removed we find above it a cartilage (_s′_)
which passes backwards between the exoccipitals, and extends as far
back as the _foramen magnum_: it corresponds to the _os occipitale
basilare_.
[Illustration: Fig. 16
Cartilaginous skull of _Rana esculenta_, from below, twice natural
size. Cartilage shown by stippling.
_c_ Cartilage of prootic.
_e_ Sphenethmoid.
_fp_ Fronto-parietal.
_i_ Premaxillary.
_j_ Quadrato-jugal.
_m_ Maxillary.
_n_, _sn_ Cartilaginous nasal skeleton.
_n′_, _n″_, _n‴_, _n⁗_ Processes of nasal cartilage.
_o_ Exoccipital.
_p_ Prootic.
_pl_ Palatine.
_pt_ Pterygoid.
_pt′_ Articular surface for pterygoid.
_r_ Optic foramen.
_r′_ Foramen for N. abducens.
_s_ Parasphenoid.
_s′_ Cartilaginous cranium.
_sp_ Cartilage of suspensorium.
_sp′_ Cartilage under squamosal.
_sp″_ Cartilage under pterygoid.
_v_ Vomer.
]
*c.* The sides of the cranium are formed almost entirely of cartilage.
This cartilage fills the space bounded by the nasals above, the
parasphenoid below, the so-called _ala magna_ of the prootic bone
behind, and the sphenethmoid in front; and has in its posterior part
an aperture (_r_) through which passes the _nervus opticus_, and below
this a smaller one (_r′_) for the _nervus abducens_. The extent of
the cartilage in the antero-posterior direction is greater in _R.
esculenta_ than in _R. temporaria_, or in other words the sphenethmoid
stretches further back in the latter than in the former.
B. THE BONES OF THE FACE.
[Illustration: Fig. 17.
Cartilaginous basis of the skull of _Rana esculenta_, from above, twice
natural size. Cartilage shown by stippling.
_a.n._ Wings of nasal cartilage.
_c.n._ Concha narium.
_e_ Sphenethmoid.
_ff′_ Foramina of cranium.
_fn_ Nasal.
_fp_ Fronto-parietal.
_i_ Premaxillary.
_j_ Quadrato-jugal.
_m_ Maxillary.
_n_, _sn_ Cartilaginous nasal skeleton.
_n′_, _n″_, _n‴_ Processes of the cartilage.
_o_ Exoccipital bones.
_p._ Prootic.
_pt_ Anterior arm of pterygoid.
_pt′_ Posterior arm of pterygoid.
_s′_ Cartilaginous cranium.
_sp_ Cartilage of suspensorium.
_sp′_ Cartilage under the squamosal.
_sp″_ Cartilage under the pterygoid.
_t^1_ Anterior }
_t^2_ Middle } arm of the squamosal.
_t^3_ Posterior}
]
The *Suspensorium*.
7. The *squamosal bones*, _ossa tympanica_, Cuvier (Figs. 10, 14 _t_).
*Cuvier*, _oss. foss._, V, 2. 390, Pl. XXIV, Figs. 1, 2
n.--*Dugès*, _temporo-mastoidien_, n. 10.--*Meckel*, Articular part
of temporal.--*Hallmann* and others, quadrate-bone.--*Parker* and
*Bettany*, _l. c._, squamosal.
The suspensorium, which forms the articulation between the cranium and
the lower jaw, is T shaped; and consists of cartilage covered by bone.
Of the three arms of the T the anterior has a free pointed extremity
(Fig. 14 _t^1_) at the postero-lateral margin of the temporo-orbital
fossa: it forms a true _processus zygomaticus_, and is bound to the
upper jaw by ligaments. In _R. temporaria_ it is comparatively much
shorter than in _R. esculenta_. The posterior upper arm (_t^2_)
articulates with the prootic bone: the third or lower arm (_t_^3),
supported by a cartilage[30], runs backwards and downwards to unite
with the side of the broad hinder extremity of the quadrato-jugal bone.
[Footnote 30: This cartilage is the quadrate cartilage of Parker;
others regard it as the upper end of the cartilaginous mandibular arch,
of which Meckel’s cartilage is the lower distal part.]
The cartilaginous basis[30] of the suspensorium (Fig. 17 _sp_, _sp′_)
is a direct continuation of the cartilaginous basis of the cranium,
and proceeds from it to the outer extremity of the prootic; from this
point the cartilage runs backwards and divides into two branches; of
these, one (_sp′_) retains the original course backwards and outwards
towards the articulation of the lower jaw, and in conjunction with the
quadrato-jugal (_j_) forms this joint. The other (_sp″_) is directed
forwards along the anterior arm of the pterygoid bone; it widens in
front (_sn_), and becomes directly continuous with the cartilaginous
strut described above as projecting from the hinder part of the
cartilaginous olfactory capsule.
*8.* The *quadrato-jugal bones*, _ossa jugalia_, Cuvier (Figs. 10,
17, 19 _j_).
*Dugès*, _tympano-malléal_, n. 11.--*Cuvier*, _l. c._, p. 399,
Pl. XXIV, Figs. 1 2 o.--*Hallmann*, quadrato-jugal bone, _l. c._,
p. 39.--*Parker* and *Bettany*, _l. c._, quadrato-jugal.
This is a small process of bone, likened by Dugès to a comma, which
rests by its posterior broader extremity on the cartilage of the
mandibular arch[1], and forms with it a portion of the articular
head for the lower jaw. The anterior extremity is pointed, directed
forwards, and attached by ligament to the maxillary bone.
*9.* The *pterygoid bones*, _ossa pterygoidea_ (Figs. 10, 11, 17, 19
_pt_).
*Cuvier*, _l. c._, p. 389, Pl. XXIV, Figs. 1, 2 m m.--*Dugès*, n.
9.--*Parker* and *Bettany*, _l. c._, pterygoid bones.
These bones, shaped like the Greek letter λ, possess each three arms:
of these the middle one is attached to the under surface of the prootic
bone by a cartilaginous process (Fig. 18 _sp_); the hinder grooved arm
lies upon the under surface of the cartilaginous suspensorial arch
(Fig. 18 _sp′_); and the anterior arm (_pt_) runs forwards along the
inner border of the anterior ramus of the suspensorium (_sp″_), in
contact with the maxillary, palatine, and nasal bones.
The cartilage just mentioned, by means of which the middle arm of the
pterygoid is connected with the cranium (compare Fig. 18), proceeds
from the cranial origin of the cartilaginous arch (_sp_), turns
downwards and then forms a sort of articular head (_cpt_), which is
articulated to an oval flat elevation of the prootic cartilage by a
movable joint. Externally the articular head curves somewhat abruptly
into the bony substance (Fig. 18 _pt_) of the pterygoid bone.
[Illustration: Fig. 18.
Origin of the suspensory cartilage (_sp_) from the skull, with
attachment of the pterygoid; front view. Cartilage shown by stippling.
_cpt_ Cartilaginous epiphyses of the pterygoid bone, from the cartilaginous suspensorium.
_j_ Quadrato-jugal bone.
_pt_ Pterygoid bone.
_sp_ Origin of suspensorial cartilage from the skull.
_sp′_ Hinder arm of same.
_sp″_ Anterior arm of same.
]
[Illustration: Fig. 19.
Cartilaginous skull of _Rana esculenta_, from below, twice natural
size. Cartilage shown by stippling.
_c_ Cartilage of prootic.
_e_ Sphenethmoid.
_fp_ Fronto-parietal.
_i_ Premaxillary.
_j_ Quadrato-jugal.
_m_ Maxillary.
_n_, _sn_ Cartilaginous nasal skeleton.
_n′_, _n″_, _n‴_, _n⁗_ Processes of nasal cartilage.
_o_ Exoccipital.
_p_ Prootic.
_pl_ Palatine.
_pt_ Pterygoid.
_pt′_ Articular surface for pterygoid.
_r_ Optic foramen.
_r′_ Foramen for N. abducens.
_s_ Parasphenoid.
_s′_ Cartilaginous cranium.
_sp_ Cartilage of suspensorium.
_sp′_ Cartilage under squamosal.
_sp″_ Cartilage under pterygoid.
_v_ Vomer.
]
*10.* The *maxillary bones*, _ossa maxillaria superiora_, Cuvier
(Figs. 10, 11, 17, 19 _m_).
*Cuvier*, _l. c._, p. 389, Pl. XXIV, Figs. 1, 2 k k.--*Dugès*, n.
4, _maxillo-jugal_.--*Parker* and *Bettany*, _l. c._, maxillary
bones.
These are elongated, curved bones, narrower behind, broader in front,
and forming with the quadrato-jugals the bony support of the face. The
superior surface is convex and directed outwards, the inferior surface
is grooved and bears teeth along the outer edge of this groove. From
the upper and inner border of the anterior half of this bone a process
(_processus frontalis_) passes upwards, which articulates with the
nasal bone. The anterior extremity of the bone articulates with the
premaxillary bone, the posterior with the quadrato-jugal.
The maxillary bone articulates at its anterior end (Fig. 19 _n″_) with
a process of the cartilaginous capsule of the nose. The broad plate of
cartilage (Fig. 19 _n_), under cover of the _processus frontalis_,
connects the hindermost transverse portion of the nasal cartilage
with the cartilage which runs forwards from the suspensorium upon the
anterior arm of the pterygoid.
*11.* The *nasal bones*, _ossa fronto-nasalia_, Dugès (Figs. 10, 17
_fn_).
*Cuvier*, _frontale anterius_, _l. c._, h.--*Dugès*, n.
2.--*Meckel*, nasal bone.--*Parker* and *Bettany*, _l. c._, nasal
bones.
These flat, triangular bones, which rest upon the nasal cartilages
(_n_), assist to bound the orbital cavities in front, and are connected
by their external angles with the maxillary bone on either side[31].
[Footnote 31: For _os nasale_, Cuvier (_l. c._, g), _cornet_
(_concha_), Dugès, see cartilaginous nasal capsule, p. 27.]
*12.* The *premaxillary bones*, _ossa intermaxillaria_ (Figs. 10, 11,
17, 19 _i_).
*Cuvier*, _l. c._, p. 388, Pl. XXIV, Figs. 1, 2 f f.--*Dugès*, n.
3.--*Parker* and *Bettany*, _l. c._, premaxillary bones.
These two bones are united in the middle line: each consists of a
tooth-supporting portion, which completes the maxillary arch, and
an ascending process, to the apex of which the nasal cartilage is
articulated by a movable joint (_an_). As muscles are attached to this
process, it becomes a lever, by which movements are effected.
[Illustration: Fig. 20.
Skull of _Rana esculenta_, seen from below, twice natural size.
_c_ Cartilaginous wall of skull.
_e_ Sphenethmoid.
_e′_ Cartilaginous nasal skeleton.
_h′_ Stylo-hyoid.
_i_ Premaxillary.
_m_ Maxillary.
_m′_ Quadrate tract.
_o_ Exoccipital.
_p_ Prootic.
_p′_ Anterior arm of prootic.
_p″_ Trigeminal foramen.
_pl_ Palatine.
_pt_ Anterior arm of pterygoid.
_pt′_ Posterior arm of pterygoid.
_s_ Parasphenoid.
_v_ Vomer.
]
*13.* The *palatine bones*, _ossa palatina_ (Figs. 19, 20 _pl_).
*Cuvier*, _l. c._, p. 389, Pl. XXIV, Figs. 1, 2 i i.--*Dugès*, n.
7.--*Parker* and *Bettany*, _l. c._, palatine bones.
Are two transverse bony bars, situated under the anterior portion of
the sphenethmoid bone on either side: each extends outwards from the
apex of the parasphenoid to the maxillary bone, where this gives off
its ascending process to the nasal bone.
*14.* The *vomers*, _vomer_ (Figs. 19, 20 _v_).
*Cuvier*, _l.c._, p. 389, Pl. XXIV, Figs. 1, 2 l l.--*Dugès*, n.
6.--*Parker* and *Bettany*, _l.c._, vomer.
A pair of flat bones, placed horizontally on the under surface of
the cartilaginous nasal capsule in the triangular space between the
palatine bone and the anterior portion of the arch of the jaw. They
limit the outer border of the floor of this capsule, which lies in a
groove on the dorsal surface of the bone. The outer border of each bone
has three processes, and between them two notches; the hinder of these
notches bounding the posterior nares. The inner borders of the two
bones touch, and the under surface of each bears a transverse row of
small, pointed teeth.
*15.* The *mandible*, _maxilla inferior_ (Fig. 21).
*Cuvier*, _l.c._, p. 398, Pl. XXIV, Figs. 1, 2 _rst_.--*Dugès*, n.
16, 17, 18, 19.--*Parker* and *Bettany*, _l.c._, mandibular arch.
[Illustration: Fig. 21.
_A_ Mandible of _Rana esculenta_, from above, nat. size.
_B_ External view of left side, } twice nat. size.
_C_ Angulosplenial, }
1. Angulosplenial.
2. Dentary.
3. Mentomeckelian.
4, 4′ Meckel’s cartilage.
_a._ Rudimentary _processus coronoideus_.
_b._ Groove for Meckel’s cartilage.
]
The mandible consists of two bony arches united by ligament in the
middle line, and each formed of four pieces. These are, (1) the
*angulosplenial*, a strong, bony piece (Fig. 21 _C_, _B_1, _A_1),
which forms the inferior and internal part of the lower jaw; below,
it extends posteriorly, as far as the articulation; in front, it is
attached to the dentary. In the greater part of its length it has
a groove directed upwards and outwards (_C_, _b_), and above has a
process which represents the _processus coronoideus_: (2) the *dentary*
(_A_ 2, _B_ 2), a bony lamella which rests on the outer surface of
the anterior half of the angulosplenial, and articulates in front with
*Meckel’s cartilage*; it is a thin, flat lamella of bone; (3) in the
groove of the angulosplenial is found a cartilage occupying its entire
length (_A_ 4, _B_ 4), *Meckel’s cartilage*; it is broader behind,
and here forms the articular fossa of the lower jaw; anteriorly it is
covered by the dentary, and articulates with the (4) *mentomeckelian*
(_A_ 3, _B_ 3) at its anterior end, which is bound to its fellow of the
opposite side by ligaments, and unites the two halves of the lower jaw.
The upper part of Meckel’s cartilage, which forms the joint with the
suspensorium, must be regarded as the _articulare_; to this also
belongs the anterior, ossified portion of the mentomeckelian[32];
the dentary, which covers Meckel’s cartilage, must represent the _os
dentale_[33]; the first and largest bone, the angulosplenial, which
lies on the inner side of the cartilage, must be considered as the _os
operculo-angulare_, Dugès, for it contains the elements of these bones.
[Footnote 32: Dugès, _os dentale_.]
[Footnote 33: Dugès, _surangulaire_.]
[Illustration: Fig. 22.
Hyoid of _Rana esculenta_, twice nat. size.
_H_ Body; _h h′_ processes.
_H′_ Anterior horn.
_H″_ Posterior horn.
]
*16.* The *hyoid bone*, _os hyoideum_ (Fig. 22).
*Parker* and *Bettany*, _l.c._, hyoid.
This consists of a broad, thin, cartilaginous plate, with processes
passing from it as represented in the figure. We distinguish in
it:--(*a*) the body (_H_), somewhat oblong, and wider in front than
behind. From the anterior angles there projects on either side a blunt
rounded process (_h_); from either posterior angle a more pointed
process (_h′_). (*b*) The anterior cornua (_H′_) (_cornua styloidea_)
project from the anterior border of the body, first in a forward
direction, then in a curve backwards and upwards (compare Fig. 12),
to unite with the cartilage of the prootic bone. Where the direction
of these _cornua_ is changed each sends off a short blunt process.
(*c*) The posterior cornua (_cornua thyroidea_) (_H″_) are bony rods
which run from the hinder margin of the body, diverge posteriorly, and
enclose the larynx.
III. THE STERNUM (Fig. 24 _es_, _hs_).
*Cuvier*, _l. c._, p. 401, Pl. XXIV, Fig. 31 _e f_.--*Dugès*, n.
27, 28.--*Parker* and *Bettany*, _l. c._, sternum.
The bones of the sternum are in very close relationship with the
shoulder-girdle, and some difference of opinion exists as to the
relations of the several parts.
[Illustration: Fig. 23.
Omosternum of _Rana esculenta_, twice nat. size.
_a_ Anterior,
_p_ Posterior extremity.
]
The following parts must be regarded as undoubtedly belonging to the
sternum:--
*1.* An anterior part, consisting of a bony and a cartilaginous portion.
_a._ The *omosternum* (Figs. 23, 24 _e.s._) is a bony rod, wider
behind, narrower in front, and supports
_b._ The *episternum* (Fig. 24 _es′_), a semicircular plate of
calcified cartilage, with a thin free border of unchanged hyaline
cartilage.
*2.* A posterior part, which also consists of a bony and a
cartilaginous portion.
[Illustration: Fig. 24.
Shoulder-girdle and sternum of _Rana esculenta_, twice nat. size. The
scapula and suprascapula are turned outwards.
_c._ Connecting cartilage.
_cl._ Clavicles and precoracoids.
_co_ Coracoid.
_es._ Omosternum.
_es′_ Episternum.
_h_ Hyaline cartilage.
_hs._ Sternum proper.
_hs′_ Xiphisternum.
_o_ Bone.
_o′_ Calcified cartilage.
_sc._ Scapula.
_sc′_ Suprascapula.
]
_a._ The *sternum proper* (Fig. 24 _h.s._), a rod of cartilage
ensheathed in bone, broader in front and narrower behind. To its
posterior extremity is attached
_b._ The cartilaginous *xiphisternum* (Fig. 24 _hs′_), a plate, the
shape of which is best understood by referring to Fig. 24, and the
structure of which is similar to that of the episternum.
*3.* The *epicoracoids*[34] lie between the episternum and the sternum
proper: they are a pair of narrow cartilages, closely applied to each
other and placed between the ventral ends of the precoracoids and
coracoids, see p. 40.
[Footnote 34: Dugès, _l.c._, p. 61, regards the cartilaginous laminae
as _os episternale_ and _proc. xiphoideus_, and the two bones _e.s._
and _h.s._ (Fig. 24) as sternum.]
IV. THE BONES OF THE ANTERIOR EXTREMITY.
A. BONES OF THE SHOULDER-GIRDLE.
The shoulder-girdle of the frog (Fig. 25) consists of four bones, two
in the upper or *scapular portion*, and two in the lower or *coracoid
portion*.
*1.* The *scapular portion*.
*a.* The *suprascapula*, _pars suprascapularis scapulae_, _scapula
superior s. omolita_ (Figs. 25 _s′_, 26, 27). This forms the upper,
thinner portion. It is trapezoid in shape, its narrowest, thickest,
and lowest border articulating with the scapula. The remaining
three borders are free; the posterior and superior borders are very
considerably thinned out, the inferior surface is curved towards the
ventral surface. Only the thin upper and hinder borders (_hh_) are of
hyaline cartilage; the middle portion (_co_) consists of calcified
cartilage; the lateral part (_o_) and the anterior border (_o′_) of
true bone.
[Illustration: Fig. 25.
Shoulder-girdle of the frog in transverse section, diagrammatic.
_c_ Connecting cartilage.
_c′_ Epicoracoids.
_cl_ Clavicles.
_h_ Humerus.
_s_ Scapula.
_s′_ Suprascapula.
_ss_ Articulation of these two.
_v_ Vertebra.
]
The bony part forms a thin plate striated both radially and
concentrically with the margin. The anterior border (_o′_) is bent on
itself so as to form a groove (Fig. 27). The dorsal surface of this
bony plate is quite smooth, and covered only by periosteum; the ventral
surface, on the contrary, is for the most part covered by an even layer
of calcified cartilage (Fig. 27 _co′_). This passes directly into the
second portion of calcified cartilage (_co_); so that if the whole be
dried, the thin hard lamina of bone can easily be split away from the
underlying parchment-like cartilage. The layer of calcified cartilage
is, however, not so complete that the _suprascapula_ can be said to
consist of calcified cartilage.
[Illustration: Fig. 26.
Suprascapula of _Rana esculenta_, from above, twice nat. size.
_co_ Calcified cartilage.
_h_ Hyaline cartilage.
_o_ Bony portion.
_o′_ Anterior curved border.
]
[Illustration: Fig. 27.
Suprascapula of _Rana esculenta_, from below, twice nat. size.
_co_ Calcified cartilage.
_co′_ Layer of calcified cartilage on the under surface of the bone.
_h_ Hyaline cartilage.
_o_ Bony portion.
_o′_ Anterior curved border.
]
[Illustration: Fig. 28.
Left scapula of _Rana esculenta_, from below, twice nat. size.
_a_ Anterior border.
_c.a._ _Cavitas articularis._
_l_ Outer border.
_m_ Inner border.
_p_ Posterior border.
]
[Illustration: Fig. 29.
Scapula seen from behind, twice nat. size.
_c.a._ _Cav. articularis._
_d_ Dorsal process.
_v_ Ventral process.
]
*b.* The *scapula* (Figs. 25 _s_, 28, 29) is a long, flat,
four-cornered plate of compact bone, contracted in the middle, and
wider at either end. From above (Fig. 28 _l_) it descends to the
shoulder-joint with a slight curvature, with the convexity directed
outwards. The inferior or ventral border (Fig. 28 _m_), which assists
in the formation of the shoulder-joint, is cleft into two processes,
a ventral and a dorsal. This may be best seen by looking at the
border of the bone from behind or before (as in Fig. 29). The lower
ventral process (Fig. 29 _v_) may be regarded as the _acromion_, or
at least as a rudiment of the acromion, _i. e._, _spina scapulae_.
The upper dorsal process evidently represents a rudimentary _processus
coracoideus_. The anterior border (Fig. 28 _a_) is free, somewhat
sharp, and slightly concave; the posterior (Fig. 28 _p_), also concave,
is free externally; while internally, where the division of the ventral
border commences, it takes part in the formation of the articular
cavity of the shoulder (Figs. 28 and 29 _c.a._).
_Articulation with the suprascapula._ The scapula consists of a shell
of compact bony tissue and an inner portion of cancellous tissue; this
latter passes, at the boundary between this bone and the suprascapula,
through an intermediate layer of calcified cartilage, which is directly
continuous with the cartilage of the suprascapula. The compact
superficial layer ceases where the calcified cartilage begins, and the
periosteum of the scapula passes directly into the perichondrium of the
suprascapula.
*2.* The *ventral portion* of the shoulder-girdle consists of three
parts, which lie one behind the other.
*a.* The larger and posterior bone, the *coracoid* (Figs. 24 _co_,
30), is contracted in the middle, and expanded at either end,
especially at the sternal end. The inner half is flattened from above
downwards; externally it becomes more cylindrical. The anterior and
posterior borders are markedly concave; the outer border (Fig. 30 _l_)
articulates by means of a cartilage with the _proc. coracoideus_ of
the scapula; the inner border (_m_) is separated from its fellow of
the opposite side by the epicoracoids. This inner border is so broad,
that it almost touches the inner end of the clavicle (Fig. 24 _cl._). A
*coracoid foramen* is thus formed between the two bones, similar to the
_foramen ovale_ of the pelvis.
[Illustration: Fig. 30.
Left coracoid, twice nat. size.
_a_ From below.
_b_ From behind.
_l_ Outer extremity.
_m_ Inner extremity.
]
[Illustration: Fig. 31.
Clavicle of the left side, twice nat. size.
_l_ Outer extremity.
_m_ Inner extremity.
]
*b.* The small anterior bones of the ventral portion of the
shoulder-girdle (Figs. 24 _cl._, 31), I, like Cuvier and others,
regard as *clavicles*. Dugès (n. 33) names them ‘_acromial_.’ Each
bone is narrower than the coracoid, smaller internally (_m_), broader
externally (_l_), and articulates by this broader end with the
cartilage uniting the dorsal and ventral portions; the inner extremity
rests upon the epicoracoid. The clavicle is grooved on its superior
and posterior surfaces in almost its whole length; the groove widens
externally (_l_), and contains
*c.* The *precoracoid* (Fig. 34 _cl′_), a slender bar of cartilage,
connecting the anterior edge of the scapula with the sternum.
[Illustration: Fig. 32.
Right shoulder-girdle of _Rana esculenta_, from above.
_ca_ Cav. articularis.
_c c_ Cartilage.
_cl_ Clavicle.
_co_ Coracoid.
_sc_ Scapula.
_sc′_ Suprascapula.
]
[Illustration: Fig. 33
Hinder border of the scapula and coracoid, with the connecting
cartilage and shoulder-joint, twice nat. size.
_c_ Connecting cartilage.
_d_ Dorsal process.
_co_ Coracoid.
_sc_ Scapula.
_v_ Ventral process.
]
[Illustration: Fig. 34.
Clavicular cartilage of a young specimen of _Rana esculenta_, enlarged
to the adult size.
_c_ Connecting cartilage.
_e_ Epicoracoids.
_c′_ Ligament between the two cartilages.
_cl_ Clavicle.
_cl′_ Clavicle and precoracoid.
_co_ Coracoid.
_co′_ Cartilage of same.
_es_ Omosternum.
_hs_ Sternum proper.
]
*Cartilages* of the shoulder-girdle (Figs. 24, 32, 34). A cartilage
(_c_), described by Dugès as the ‘paraglénal,’ connects the scapula
with the coracoid, and converts the notch between the two processes
(_s_ and _v_) on the inner border of the scapula into an aperture
opening posteriorly into the glenoid cavity, and which is filled up by
the lining cartilage. This cartilage connects the two processes with
the coracoid; being thicker between this and the _proc. coracoideus_,
it takes an important share in the formation of the floor of the
glenoid cavity. At the outer extremity of the clavicle the cartilage
projects and is then continued in the groove on this bone towards
the middle line (Figs. 32, 34), where it widens out, and is united by
its external margin with the sternum, thus forming the precoracoid as
already described, see p. 40. These connections are best seen in young
animals, as is shown in Fig. 34.
The clavicle (_cl_) is of ossifying cartilage; the cartilage (_c_),
the epicoracoid, is very large, and hyaline, and at _cl_ runs directly
into the epicoracoids, which are here united mesially by ligament. In
the fully developed animal the whole of the epicoracoid changes to
calcified cartilage, as also does the precoracoid lying in the groove
of the clavicle.
B. BONES OF THE FORE LIMB.
*1.* The *arm* has but one bone.
[Illustration:
Fig. 35. Fig. 36. Fig. 37.
Humerus of _Rana Humerus of _Rana, Humerus of _Rana
esculenta_, female, esculenta_ male, esculenta_, female,
seen from below. seen from below. outer side.
Figures twice natural size.
_c_ Anterior extremity. _c_′ Posterior extremity. _cd_ Crista
deltoidea. _cm_ Crista medialis. _t_ trochlea.]
The *humerus*, _os humeri_ (Figs. 35, 36, 37). The shaft of the humerus
is, on the whole, cylindrical, the middle part being the narrowest;
its dorsal surface is slightly concave, the ventral surface convex. In
the upper half the cylindrical form is indistinct, from the presence
of a well-marked crest (_crista deltoidea_) upon the under or ventral
surface. The hinder half of the bone has very different shapes in
the two sexes: in the female it remains cylindrical as far as the
elbow-joint; in the male, on the posterior surface, where the _crista
deltoidea_ ceases, a marked ridge (_crista medialis_) arises, which
gradually winds inwards and terminates at the inner condyle. This
sexual difference is found in all the three species described in the
Introduction, and it would seem that this ridge increases in height
during the pairing season. The muscle which arises from this process
is the _flexor carpi radialis_ (Fig. 74 _Fc_), and it attains, in the
males, a very large size at the same period; indeed, it is at its
origin twice as broad as in the female. Dugès[35] has incorrectly
stated that this _crista_ is a peculiarity of _Rana temporaria_, and is
wanting in _Rana esculenta_. Pouchet[36] first observed that it was a
sexual distinction.
[Footnote 35: _l. c._, p. 68.]
[Footnote 36: Compt. rend. vol. XXV, 1847, p. 761.]
The anterior articular extremity presents a rounded head, which is
somewhat flattened externally. The inferior ventral border is sharp,
and developed into the above-mentioned bony crest (_crista deltoidea_);
the free border is arched and curved outwards. Above, on the outer
surface of the head, is found an eminence which may be a rudimentary
_tuberc. maius_. The inner half of the head is articular.
The posterior articular extremity consists of a rounded head (_c′_),
attached to the posterior extremity of the shaft; internal to this is
a small _trochlea_ (_t_), placed upon the inner condyle. The external
condyle is but small. The head is embraced by these condyles. Upon the
under surface, above the head, is the _fossa cubitalis anterior_. The
structure of the two articular extremities of the humerus differs; the
upper, as in long bones generally (see page 16), consists of hyaline
cartilage surrounded by calcified cartilage, which again is covered by
hyaline articular cartilage; the lower extremity is composed of spongy
bone, with roundish marrow spaces, and for the most part covered by a
layer of calcified cartilage.
The *shoulder-joint*. The socket is formed by the posterior border of
the scapula, by both the processes of that bone, the outer portion of
the coracoid, and besides these by cartilage, which forms the articular
surface already described (Fig. 33). In the macerated bone the floor
of the socket opens dorsally into a fossa between the processes of the
scapula (Fig. 32). This opening, in the natural condition, is closed by
synovial membrane only; the cartilage covering the rest of the space
being absent (the sac may easily be inflated, either from the joint
itself or through the opening). The margin of the socket consists of
a _labrum_, partly fibrous and partly cartilaginous, which is easily
removed entire. The capsule, which is attached beneath the _caput
humeri_, arises from this. From the articular cartilage of the ventral
margin of the socket, and from the adjacent part of the scapula,
proceeds a strong band, which is inserted into the flattened outer
surface of the head.
*2.* The *forearm*.
[Illustration: Fig. 38.
Radio-ulnar of the right side of _Rana esculenta_, twice nat. size.
_r_ Radius.
_r_′ Capitulum radii.
_u_ Ulna.
_u_′ Olecranon.
]
The *radio-ulnar*, _os antibrachii_ (Fig. 38). The two bony elements
of the forearm are fused into one, which, however, shows traces of its
compound character. Of these two bones, that which forms the inferior
(in man anterior) border is the radius, the other the ulna. The
relative positions of the bony elements are such that they appear to be
in a state of semi-pronation; by this the thumb-border of the arm is
directed downwards (in man forwards). The two bones so united form a
flattened, tube-like bone, the grooved surfaces of which are directed
inwards and outwards respectively; the borders being dorsal and
ventral. The shaft of the bone is narrower above, becoming gradually
wider below. In the upper half, the groove showing the line of junction
of the two bony elements is scarcely visible, and it appears as
though this part consisted of ulna alone, the radius not reaching so
far; below the groove is more marked. The upper articular extremity
appears to consist of an _olecranon_ (Fig. 38 _u′_) and a _processus
coronoideus_ (_r′_), between which is the greater sigmoid cavity
(_cavitas sigmoidea major_) for the _processus cubitalis humeri_. A
more careful examination shows this to be incorrect: the portion of the
concave articular surface, which lies in the immediate neighbourhood
of the ventral border, undoubtedly represents the articular surface of
the _capitulum radii_, and the upper portion of the articular surface
(at _u′_) belongs to the _ulna_ and articulates with the _trochlea_
(Figs. 35, 36 _t_) of the humerus. The inner border of the upper
extremity of the bone articulates with the groove _t_ of the humerus.
The inferior extremity forms one of the usual cartilaginous epiphyses,
enclosing the two bones. That part of the extremity corresponding with
the radius is triangular and convex, it is prolonged upon the inner or
under surface of the bone by means of a process; the ulnar portion of
the bone forms a _capitulum_. The structure of the inferior extremity
is that of epiphyses in general, except that there are two medullary
cavities in a common sheath of calcified cartilage; the anterior head
consists of cancellous tissue, with a covering of calcified cartilage.
*3.* Bones of the *hand* (Fig. 39).
*Dugès*, Pl. VIII, Figs. 37, 38, 39, 40, 41, 42, 43, 52.
*a.* Bones of the *wrist*, _ossa carpi_. These are arranged in two
rows, proximal and distal. The proximal or anterior row has three
bones, viz.:--
1. _Os lunatum_, the middle bone (Fig. 39 _l_), Dugès, n. 38,
articulates with the radial part of the articular surface of the
radio-ulnar by a concave surface; with the large bone of the second
row (_hc_) it articulates by means of a rounded head; and with the
two other bones of this row, _os naviculare_ (_n_) and _pyramidale_
(_p_), with the former by a saddle-shaped surface, with the latter
chiefly by ligament. The bone is irregularly cuboid; the dorsal and
palmar surfaces are non-articular. With Dugès I regard this bone as _os
lunatum_; Mertens[37] regards it as _os naviculare_.
[Footnote 37: Mertens, _l. c._]
[Illustration: Fig. 39.
Bones of the forearm and hand of _Rana esculenta_, right side, dorsum,
twice nat. size.
_a_ Os antibrachii.
_hc_ Os capitato-hamatum.
_l_ Os lunatum.
_m_ Ossa metacarpi.
_n_ Os naviculare.
_p_ Os pyramidale.
_r_ Radial portion of the radio-ulnar.
_t_ Os multangulum majus or trapezium.
_t′_ Os multangulum minus or trapezoides.
_u_ Ulnar portion of the radio-ulnar.
_I_-_V_ First to fifth fingers, the fifth only
of os metacarpi, the second and third of
two, fourth and fifth of three phalanges.
]
2. _Os pyramidale_ (Fig. 39 _p_), Dugès, n. 37, articulates with the
ulnar part of the posterior articular extremity of the radio-ulnar.
Anteriorly the bone has a facet which receives the _capitulum ulnae_,
and alongside this a small flat surface which articulates with the
radius. Posteriorly, opposite to the second row, it presents a long
raised articular surface, extending from the dorsum to the palmar
surface; and on the palmar aspect of the bone is a ridge running from
before backwards. Mertens names this bone _os lunatum_.
3. _Os naviculare_ (Fig. 39 _n_), Dugès, n. 39. The third bone of the
first row does not articulate with the bones of the forearm. It is
connected with the _os lunatum_ by a saddle-shaped surface, posteriorly
with the _os capitatum_ by means of a concave surface. On the inner
surface is a small concave articular facet for the _os multangulum
minus_ or _trapezoides_ (Fig. 39 _t′_). The convex palmar surface of
the bone articulates with the _os multangulum majus_ (_t_); the radial
side is non-articular, and with the _os lunatum_ forms a ridge directed
forwards. Mertens names this bone _os triquetrum_. It is evident,
however, that if the arrangement in man obtains as a standard, the
nomenclature of Dugès, which I have here used, is correct; but the _os
naviculare_ is no longer in contact with the articular surface of the
_os antibrachii_.
The second or distal row also consists of three bones:--
4. _Os capitato-hamatum_ (Fig. 39 _hc_), Dugès, n. 40, 41, 42,
corresponds with the _os capitatum_ and _hamatum_[38], which are here
fused together. It is the largest bone, and articulates with all three
bones of the first row; it is crescentic, with the concavity directed
posteriorly, and on the convex surface has three facets for the three
outer _ossa metacarpi_.
[Footnote 38: Dugès thinks that _os trapezoides_ is also included.]
5. _Os multangulum minus_, _s. trapezoides_ (Fig. 39 _t′_), Dugès, n.
43, is a small bone lying next to the foregoing; it articulates with
the _os metacarpi II_, and anteriorly with the _os naviculare_. Dugès
considers it to be the _os trapezium_.
6. _Os multangulum majus_, _s. trapezium_ (Fig. 39 _t_), is a small
bone, which is placed on the convex palmar auricular side of the _os
naviculare_. Dugès regards this bone as _os metacarpi pollicis_ (Dugès,
n. 44), Mertens as _multangulum minus_. It appears to me that the
interpretation here given is justified, because it articulates with the
rudiment of the thumb, and as it possesses no resemblance to a long
bone it cannot be regarded as an _os metacarpi_.
*Structure of the carpal bones.* All the carpal bones consist of
calcified cartilage, though variations due to age occur in the amount
of the deposit.
*Wrist joint.* As stated above, the _os lunatum_ and _os pyramidale_
are articulated with the forearm. In addition to the capsules uniting
the parts, there are strengthening ligaments, two of which require
special mention. One of these arises from the palmar surface of the
posterior extremity of the ulna, and passes to the sharp palmar ridge
of the _os pyramidale_, where it is attached, and is inserted into the
_os capitato-hamatum_; the second ligament passes in a similar manner
on the palmar surface from the radius to the _os naviculare_. Between
the two ligaments there is on the volar surface a deep excavation.
[Illustration: Fig. 40.
Bones of the forearm and hand of _Rana esculenta_, right side, dorsum,
twice nat. size.
_a_ Radio-ulnar.
_hc_ Os capitato-hamatum.
_l_ Os lunatum.
_m_ Ossa metacarpi.
_n_ Os naviculare.
_p_ Os pyramidale.
_r_ Radial portion of the radio-ulnar.
_t_ Os multangulum majus or trapezium.
_t′_ Os multangulum minus or trapezoides.
_u_ Ulnar portion of the radio-ulnar.
_I_-_V_ First to fifth fingers, the first only
of a metacarpal, the second and third of
two, fourth and fifth of three phalanges.
]
*Movements* of the hand. The two bones of the forearm being firmly
united, pronation and supination, as in man, are impossible. The
normal position, as already remarked (see radio-ulnar), is that of
semi-pronation (compare Figs. 2 and 74). If the animal be in its
natural posture, with the arm bent at the elbow (Fig. 1) it can touch
the ground with the ulnar border only; but when the whole surface of
the hand rests upon the ground, the action is brought about as follows:
the plane of the carpus is in extension parallel with that of the
forearm; in flexion, almost at right-angles with that plane (Fig. 74)
The _os lunatum_ glides on the prolongation of the articular surface
on the inner palmar surface of the radius, while the _os pyramidale_
is held firmly by the ligament just described. The hand follows the
movement of the _os lunatum_, and at the same time the three outer
_ossa metacarpi_ gliding with it inwards, the fingers of the hand turn
inwards.
*b.* The Bones of the *metacarpus*, _ossa metacarpi_ (Fig. 40 _m_).
Of these there are five: the *second* to the *fifth* are of about
equal length; the first, forming the rudiment of the thumb, hidden
beneath the skin, is much shorter. This metacarpal bone of the *thumb*
is regarded by Dugès and others as the first phalanx. My reason for
describing it as a metacarpal has already been given. This bone
also presents differences in the two sexes. Meckel’s[39] observation
that it exists only in the male is incorrect; it is a large, broad
and sickle-shaped mass of calcified cartilage or even true bone,
while in the female it is simply a small cartilaginous rod; as this
almost entirely disappears in dried specimens, Meckel’s statement is
explained. The *second* finger has in the frog assumed the functions
of the thumb, and, in the males, in the breeding season swells and
undergoes an essential alteration of structure. The metacarpal of
this finger also displays differences in the sexes, being in the male
stronger, broader, and on the inner side provided with a spine-like
prolongation, for the tendon of the _abductor digiti II (pollicis)
longus_, which attains an unusual development during the breeding
season. The remaining metacarpal bones, the *third*, *fourth*, and
*fifth*, are of similar form, the last being provided with a tubercle.
The anterior articular extremities are rather broad and concave, and
the posterior have rounded heads.
[Footnote 39: _l. c._, II, 464.]
*c.* The *phalanges*, _phalanges digitorum_. The hand has four fingers
and the rudiment of a fifth, which latter is completely hidden under
the skin, and as already explained, consists of a metacarpal only. Of
the four fingers, the fourth is the longest, the third the shortest,
the second and fifth of intermediate and about equal length; the fourth
and fifth fingers have each three phalanges, the second and third have
each two. Their shape is not unlike that of the human phalanges.
V. THE BONES OF THE HINDER EXTREMITY.
A. BONES OF THE PELVIC GIRDLE (Fig. 41).
The *pelvis* has a characteristic V-shape, the pubic and ischiatic
bones of the two sides together forming a vertical plate (_a p_), which
divides anteriorly into the two iliac bones (_il_). The pubic and
ischiatic bones being united by their median surfaces, one can only
speak of the pelvic cavity as the space between the two ilia.
*1.* The *ilia*, _ossa ilii_ (Fig. 42 _il_). In these a broader part
or body can be distinguished, which takes part in the formation of the
_acetabulum_ (_a_). The hinder and broadest part of the bone is joined
to the corresponding portion of its fellow by ligament; anteriorly the
two diverge, bounding a cone-shaped cavity, the pelvis. The suture, by
which the body of the iliac bone is united with the ischiatic and pubic
bones, runs from above downwards through the middle of the _acetabulum_
(Fig. 42, from _p_ through the _acetabulum_ to _is_). Inferiorly and
in front the united _ilia_ form a prominence (_s_), which represents
the _symphysis oss. pub._ of man. The expanded portions of the ilium
rest directly over the articular cavity by means of a somewhat
constricted part or root. The _ala_ is a sabre-like bone, with the
sharper, more convex border directed upwards; the more concave, thicker
border downwards. The two surfaces, of which the inner is grooved,
are directed respectively inwards and outwards. The broader part of
the blade springs directly from the neck or root (at _il′_), and at
this end of the sharp convex border is a process, _process. sup._,
from which the tendon of the _m. vastus externus_ arises. The anterior
end of the blade is a hollow cylinder, containing cartilage, movably
articulated to the transverse process of the last vertebra or sacrum.
[Illustration: Fig 41.
Pelvis of _Rana esculenta_, from below, nat. size.
_a_ Acetabulum.
_il_ Iliac bone.
_p_ Pubic bone.
]
[Illustration: Fig. 42.
Pelvis of _Rana esculenta_, left side, twice nat. size.
_a_ Acetabulum.
_d_ Upper sharp border.
_il_ Iliac bone.
_il′_ Superior process.
_is_ Ischium.
_is′_ Tuber ischii.
_p_ Os pubis.
_s_ Inferior process of the ilium.
_v_ Lower border of same.
]
*2.* The *ischia*, _ossa ischii_ (_is_), are irregular, four-cornered
plates of bone, united together by the whole extent of their inner
surfaces. The vertical plate formed by the union of the two bones takes
only a very small share in the formation of the articular cavity.
Above, it has a somewhat sharp border, continued with the ilium into
a process (_is′_) corresponding with the united _tubera ischii_; the
hinder border, which is united below with the pubic cartilage, is
curved.
[Illustration: Fig. 43.
Horizontal section through the iliac, pubic, and ischiatic bones.
_a_ Acetabulum.
_il_ Ilium.
_is_ Ischium.
_p_ Pubic cartilage.
_s_ Ligaments which unite the bones of opposite sides.
]
*3.* The *pubes*, _os pubis_ (Figs. 41, 42, 43 _p_). Ossified pubic
bones do not exist; even in old animals they are composed of calcified
cartilage. Each is a triangular cartilage, wedged between the ilium and
ischium, but also taking part in the formation of the _acetabulum_. The
pubes of opposite sides are, as shown in section in Fig. 43, united by
ligaments in the median plane.
B. BONES OF THE HIND-LIMB.
*1.* The *thigh*.
The *femur*, _os femoris_ (Fig. 44). The shaft is cylindrical, with a
slight double or S-shaped curve. In the anterior portion the convexity
is directed upwards, in the two hinder thirds downwards. Towards the
hinder extremity it is flattened from above downwards. The anterior
extremity is a rounded articular head placed directly on the shaft
like that of the _humerus_. This head is somewhat flattened from side
to side; and in structure resembles that of the humerus. The inferior
extremity is rounded below, but flattened above (towards the hollow of
the knee) and behind.
*Hip-joint.* The articular cavity is deepened by a fibrous ring,
_labrum cartilagineum_, which fits closely upon the _caput femoris_;
from this _labrum_ the joint-capsule arises, to be inserted behind the
head; close to the lower border of the cavity a _ligamentum teres_
arises, which is inserted into the _caput femoris_.
*2.* The *leg*.
[Illustration: Fig. 44.
Femur of _Rana esculenta_, right side, twice nat. size.
_a_ Anterior extremity.
_p_ Posterior extremity.
]
*Tibio-fibula*, _os cruris_ (Fig. 45). This consists of a single bone,
the _os cruris_; it is often called the _tibia_, but presents, however,
distinct indications of being formed of two bones, the _tibia_ and
_fibula_. The shaft is not quite straight; it is thinner in the middle
and flattened from above downwards. On the upper as also on the lower
surface of the bone is a groove, passing from the middle towards each
extremity; this deepens as it proceeds, and is an indication of the
compound nature of the bone. In the middle of each surface of the bone
is the opening of a canal, through which a bristle may be passed: the
canal has bony walls. The medullary cavity is, for the most part,
double, being single only in the middle. The anterior extremity is
articular, and presents a median groove, which is prolonged on to the
under surface. The posterior extremity forms a transverse condyle,
which has at its inner part a notch for the tendon of the _m. tibialis
posticus_.
[Illustration: Fig. 45.
Tibio-fibula of _Rana esculenta_, twice nat. size, seen from below.
_a a_ Grooves.
_f_ Foramen nutritium.
_t_ Anterior articular extremity.
_t′_ Posterior articular extremity.
_t″_ Groove on malleolus internus for tendon of _m. tibialis posticus_.
]
The *knee-joint* consists of a capsule strengthened by the insertions
of numerous tendons. Within this the articular surfaces of the _femur_
and tibio-fibula are connected by means of fibro-elastic bands, which
spring from the latter bone and cross each other, thus representing the
_lig. cruciata_. The articular surfaces are moreover deepened by loose
semilunar cartilages, corresponding with the inter-articular cartilages
of the knee-joint of man. In addition, on either side of the joint, are
found auxiliary ligaments.
[Illustration: Fig. 46.
Section of the tibio-fibula through the under extremity.
_a_ Cartilaginous epiphysis.
_m_ Marrow cavities.
_t″_ Connecting mass.
_t t′_ The two cylinders of bone.
]
*3.* The *foot* (Fig. 47).
*a.* The *ankle*, _ossa tarsi_. The *tarsus* consists of two rows of
bones.
α. The *proximal row* consists of two long tubular bones (Fig. 47
_ac_), which are parallel to each other, and undoubtedly correspond
with the *astragalus* (_talus_) and *calcaneum*. The bones are
separated in the middle, but approach each other at either end. The
outer of these bones (_c_) I have named calcaneum, following Cuvier
and Dugès; the inner, astragalus (_a_). The two bones are surrounded
and enclosed at their anterior and posterior extremities in a common
epiphysis of calcified cartilage, which has the usual structure found
elsewhere. The _ligamentum calcanei_, which will be described below
(see Muscles of Foot, Fig. 88 _lc_), may be regarded as an unattached
process of the heel[40].
[Footnote 40: Meckel, _l. c._, II, p. 488, regards the cartilage in the
_tendo Achillis_ as such.]
β. The *distal* row of the tarsals are all composed of calcified
cartilage. They are:--
1. _Os cuboideum_ (Fig. 47 _cb_), a flat plate of cartilage, concave
in front, convex behind, placed between the common epiphysis of the
astragalus and calcaneum (_ac_) and the _ossa metatarsi II_ and _III_.
This corresponds, as Dugès suggests, with the separated _os cuboideum_
and _cuneiforme III_ of other batrachians, _e. g._ Bufo.
2. On the inner side of the above, between the _astragalus_ and
_metatarsus I_ lies a small body, concave in front, convex behind,
which we may regard, with Dugès, as the analogue of the _os naviculare_
(Fig. 47 _n_).
[Illustration: Fig. 47.
Right foot of _Rana esculenta_, palmar surface, twice nat. size.
_a_ Astragalus.
_ac_ Common epiphysis.
_c_ Calcaneum.
_cb_ Os cuboideum.
_h_ First, _h′_ second cartilage of supplemental toe.
_m_ Ossa metacarpi.
_n_ Os naviculare.
_I_ to _V_ First to fifth toe.
]
3. This latter supports a cartilage which forms a projection on the
inner border, covered with skin. This consists of closely-united
pieces, a small round, basal piece (_h_), and a flattened beak-like
piece (_h′_). Dugès considers these pieces as the first and second
_ossa cuneiformia_; I rather incline to Meckel’s opinion that they
represent a rudimentary hallux, the first being the _os metatarsi_, the
second a _phalanx_. Both are composed of calcified cartilage; in _R.
temporaria_ the lime-deposit seems to be less than in _R. oxyrhinus_
and _R. esculenta_, and the projection consequently softer[41].
[Footnote 41: In the text these two cartilages are termed the
‘supplemental toe.’]
*b.* The *metatarsal bones*, _ossa metatarsi_ (Fig. 47, _m_ _I_-_V_).
The five _ossa metatarsi_ are long, thin tubular bones, the anterior
articular extremities of which are broader above and narrow below,
hence are wedge-shaped, and anteriorly present flat surfaces for
articulation with the _tarsus_. The shafts are long and thin; the
posterior extremities have rounded heads. The comparative length of
these is as follows: the fourth is the longest, then come the third,
fifth, second, and first in order. In structure they resemble other
tubular bones.
*c.* The *phalanges*, _phalanges digitorum_ (Fig. 47). The total
lengths of the separate toes correspond with that of the _ossa
metatarsi_, but the distinctive differences are increased, partly by
the difference in number and partly by the varying lengths of the
phalanges. The first and second toes have each only two phalanges, the
third and fifth have each three, the fourth, which is the longest, has
four. The terminal phalanges are somewhat hooked towards the plantar
surface.
SECTION II.
THE MUSCLES.
THE MUSCLES.
LITERATURE.
Anonymous, Ueber das Schultergerüst der Schildkröten mit den
daran sitzenden Muskeln. Isis, 1827. (Contains remarks on the
shoulder-muscles of the frog.)
*Carus*, *C. G.* (1) Lehrbuch der vergleichenden Zootomie. 2nd Edit.
Leipzig, 1834. (2) Erläuterungstafeln zur vergleichenden Anatomie.
1 Part. 1826. (Muscles of the Leg.)
*Chappuis*, Morphologische Stellung der kleinen hintern Kopfmuskeln.
Zeit. f. Anat. u. Entwickl. 1876. Vol. II, pages 287–297.
*Cuvier*, Leçons d’anatomie comparée. Paris, 1835. Vols. I, II.
*Dugès*, Recherches anatomiques et physiologiques sur la déglutition
dans les Reptiles. Ext. des Annales des Sciences naturelles.
Paris, 1827.
*Dugès*, Leçons d’anatomie comparée. Paris, 1835.
*Duméril and Bibron*, Erpétologie générale ou Histoire complète des
Reptiles. 1836.
*Führbringer*, Zur vergleichenden Anatomie d. Schultermuskeln.
Jenaische Zeitschr. 1873. Vol. VII.
*Klein*, Beiträge zur Anatomie der ungeschwänzten Batrachier (Rana
temporaria, L.): in Jahrshefte des Vereins für vaterländische
Naturkunde in Würtemburg. 6 Jahrgang. 1850. Page 1.
*Kuhl*, Beiträge zur Zoologie der Rana esculenta: in Beitr. z. Zool.
Frankfurt, a. M. 1820. Page 115.
*de Mann*, Vergelykende myologische en neurologische studien over
Amphibien en Vogels. Acad. Proefschrift. 1873.
*de Mann*, Myologie comparée de l’extrémité post. chez les
amphibiens. Niederl. arch. f. Zool. 1874. Vol. II.
*Marshall*, The Frog. London and Manchester. 2nd Edit. 1885. Pages
60–71.
*Martin St. Ange*, Annales des sciences naturelles. Vol. XXIV. 1831.
Page 393.
*Meckel*, System der vergleichenden Anatomie. Halle, 1828. Vols. III
and IV.
*Pfeiffer*, Zur Anatomie des Schultergürtels und der Schultermuskeln
bei Säugethieren, Vögeln und Amphibien. Giessen, 1854.
*Rymer Jones*, Article ‘Reptiles’ in Todd’s Cyclop. of Anatomy and
Physiology. 1847–1852. Vol. IV. Page 263.
*Stannius*, Handbuch der Anatomie der Wirbelthiere. Vol. II. Zootomie
der Amphibien. Berlin, 1856.
*Wagner*, Icones Zootomicae. Leipzig, 1841.
*Wagner*, Lehrbuch der vergleichenden Anatomie. Leipzig, 1834–35.
*Zenker*, Batrachomyologia. Diss. Jena, 1825.
THE MUSCLES.
I. MUSCLES OF THE HEAD.
I. MUSCLES OF THE EYE.
*1.* _M. rectus inferior_ (Fig. 48 _ri′_).
*Dugès*, post-orbito-sous-oculaire, n. 12.--*Zenker*, _depressor
oculi_.
This muscle arises by a very thin, almost thread-like tendon from the
parasphenoid, near the _foramen opticum_, and becomes rapidly broader;
it lies beneath the tendon of the _membrana nictitans_ and a part
of the _m. retractor bulbi_: then runs forwards and outwards to be
attached into the lower part of the circumference of the eyeball.
[Illustration: Fig. 48.
Eye muscles of _Rana esculenta_, from below.
On the right side (_i. e._ in the left eye) the lev. bulbi (_l_) is
taken away; on the left side it is still present.
_l_ M. levator bulbi.
_l.a_ M. lev. anguli scapulae
_oi_ M. obliquus inferior.
_os_ M. obliquus superior.
_p_ M. pterygoideus.
_r_ M. retractor bulbi.
_re_ M. rectus externus.
1 First cervical vertebra.
]
*2.* _M. rectus externus_ (Fig. 48 _re_).
*Dugès*, post-orbito-ex-oculaire, n. 14.
Arises by a thin, thread-like tendon from the parasphenoid near the
_foramen opticum_, internal to and a little behind the _m. rectus
inferior_: it then passes obliquely outwards over the _m. retractor
bulbi_ and the tendon of the _membrana nictitans_, to be inserted into
the outer and hinder part of the circumference of the eyeball.
*3.* _M. rectus internus_ (Fig. 48 _ri_).
*Dugès*, post-orbito-in-oculaire, n. 13.
A long, thin muscle, which arises by a thread-like tendon from the
parasphenoid at the inner and hinder angle of the orbit, passes along
its inner wall, and is inserted into the antero-internal part of the
circumference of the eyeball.
*4.* _M. rectus superior_ (Fig. 49 _rs._).
*Dugès*, post-orbito-sous-oculaire.
Arises by a slender tendon from the fronto-parietal bone, widens
rapidly, and runs forwards and outwards to be inserted into the upper
part of the circumference of the _bulbus_.
[Illustration: Fig. 49.
Eye-muscles of _Rana esculenta_, from above.
_n_ Membrana nictitans.
_n′_ Tendon of membrana nictitans.
_p_ M. pterygoideus.
_rs._ M. rectus superior.
_t_ M. temporalis.
]
*5.* _M. obliquus inferior_ (Fig. 48 _oi_).
*Dugès*, pré-sous-orbito-oculaire.
This muscle arises near the floor of the orbital cavity, at the inner
and anterior angle, from the palatine bone by a thin and long tendon,
runs under Harder’s gland outwards and backwards, and is inserted,
almost at a right angle with the axis of the eye, into the anterior
part of the circumference of the eyeball.
*6.* _M. obliquus superior_ (Fig. 48 _os_).
*Dugès*, pré-sus-orbito-oculaire, n. 7.
The tendon of this small muscle arises from the inner end of the
palatine bone, near the origin of the _m. obliquus inferior_, runs
upwards, backwards, and outwards, and passes into a flat muscle, which
rapidly becomes broader, and is inserted into the upper surface of the
eyeball.
[Illustration: Fig. 50.
Eye-muscles of _Rana esculenta_, from below, the m. recti and obliqui
have been removed.
_n′_ Tendon of membrana nictitans.
_r_ M. retractor bulbi, lower part.
_r′_ Second part of same.
]
*7.* _M. retractor bulbi_ (Figs. 48 _r_, 50 _r_, _r′_).
*Dugès*, orbito-post-oculaire or choanide, n. 10.--*Zenker*, _m.
opticus_.
This muscle surrounds the optic nerve, and is situated within the
cone formed by the four recti muscles; it consists of three portions,
which take their broad and fleshy (the _recti_ and _obliqui_ arise
by thin tendons) origins from the under surface of the parasphenoid.
The first portion (Fig. 50 _r_) arises from the under surface of the
parasphenoid, nearly as far as the middle line, is broad and fleshy,
and covers, from below, the tendon of the _rectus externus_, then runs
forwards and outwards. The second portion (_r_′), which lies over
this and the tendon of the _m. rectus externus_, has also a broad and
fleshy origin, but runs more directly forwards, slightly crossing the
preceding. The third portion arises above the two others by a strong
thin tendon from the parasphenoid: it runs almost in the direction of
the _m. rectus internus_, but more directly forwards. The first two
portions pass more to the upper surface of the eyeball, the third more
to the under surface; consequently the whole muscle forms a sheath
surrounding the eyeball. The fibres to the upper surface of the eyeball
are inserted somewhat in front of the equator of the eyeball, those to
the under surface somewhat behind it.
*8.* _M. levator bulbi_, Dugès (Figs. 48 _l_, 51 _l_, 52 _l_).
*Dugès*, fronto-pterygoidien, n. 9.--*Klein*, _sustentator bulbi_.
[Illustration: Fig. 51.
Transverse section through the skull and orbital cavities of _Rana
esculenta_.
_b_ Bulb of eye.
_c_ Skull cavity.
_g_ Mucous membrane.
_l_ M. levator bulbi.
_m_ Upper jaw.
_n_ Membrana nictitans.
_n_′ Continuation of same to the lower eyelid.
_p_ Upper eyelid.
]
[Illustration: Fig. 52.
_M. levator bulbi_ of _Rana esculenta_, seen from above; the eyeball
which rests on it has been removed.
_d_._p_ M. depressor palpebrae inferioris.
_l_ M. levator bulbi.
_n_ Membrana nictitans.
_p_ M. pterygoideus.
_t_ M. temporalis.
]
There is no bony floor to the orbital cavity, and the oral and orbital
cavities are only separated by soft tissues; these are:--the mucous
membrane of the mouth, a thin fascia, and above this the muscle under
consideration. The fibres of this muscle run from before and from the
inner side obliquely backwards and outwards, below all the remaining
muscles of the eye, with the exception of the origin of the _m.
retractor bulbi_, and the tendons of the _m. obliquus inferior_, and
the _m. pterygoideus_; they arise on the inner side from the upper
and outer border of the fronto-parietal bone (Fig. 51), also from the
transverse portion of the parasphenoid and pterygoid bones, anteriorly
from the sphenethmoid and palatine bones; they run first downwards,
then, in the direction indicated, underneath the eye; and are inserted
externally by means of tendinous fibres into the superior border of the
upper jaw.
*9.* From the foregoing muscle certain fibres pass to the lower
eyelid, which may be regarded as a *depressor palpebrae inferioris*
(Fig. 52 _d.p_).
Manz[42] has described a muscle as _depressor palpebrae inferioris_
which arises in the neighbourhood of the external angle of the eye,
somewhat behind and below the lower border of the orbit, thence
passes obliquely upwards to be inserted into the lower eyelid. This
description is right as regards the insertion, but needs correction as
regards the origin. The muscle is attached to the orbital border in so
far that the tendinous expansion, into which the _levator bulbi_ passes
at its external border, is attached into the upper jaw; this bundle
splits off from the upper surface of the _levator bulbi_ at its middle,
and runs outwards on the under surface of the eyeball to the hinder
part of the lower eyelid.
[Footnote 42: Manz, Berichte der naturf. Gesellschaft zu Freiburg, 2
Band, 4 Heft, 1862, p. 391.]
[Illustration: Fig. 53.
Eye-muscles of _Rana esculenta_, from below, the m. recti and obliqui
have been removed.
_n_′ Tendon of membrana nictitans.
_r_ M. retractor bulbi, lower part.
_r_′ Second part of same.
]
*10.* Tendon of the _membrana nictitans_[43] (Fig. 53 _n_′).
The pigmented free border of the nictitating membrane passes, at the
inner and outer angles of the eye, into a tendon which passes for some
distance through fibrous tissue, then descends to the under surface
of the eyeball and joins that of the opposite side, so that the free
border of the eyelid, together with this tendon, form a complete ring.
The tendinous part of the ring, which is thin and thread-like, is found
on the under surface of the eyeball, and lies under the _m. retractor
bulbi_, and is bound to this muscle by connective tissue. Manz is
right in saying that the two muscles described by Dugès as _levatores
palpebrae inferiores_ (orbito-palpebral anterieur and posterieur, n. 5
and 6) do not exist; as is also the suggestion that he has confounded
the tendon of the nictitating membrane with these; this is clearly
shown in the figure in Plate VI of Dugès. With regard to the *actions*
of these eye-muscles, it is plain that the four straight and two
oblique muscles rotate the eyeball about three axes, one the axis of
the eye, one vertical, and the third passing from behind forwards and
inwards. The _m. retractor_ pulls the eyeball into the orbital cavity
backwards and downwards, while the _levator_ raises it.
[Footnote 43: Compare Manz, _l. c._]
There is less agreement about the movements of the eyelids, or rather
of the lower eyelid, for the upper has no independent movements.
Dugès (_l. c._) says that the two muscles, which he considers to be
_levatores palpebrae inferiores_, and which, according to him, are
connected with the _m. retractor bulbi_, draw up the lid as it is being
drawn backwards and downwards by the latter muscle. The depression
of the lid on the relaxation of the retractor and projection of the
eyeball is due simply to elasticity. Manz[44], on the contrary,
has shown that the sinking of the eyeball by the contraction of
the _retractor_ must necessarily cause a rising of the nictitating
membrane, as its tendons are attached to that muscle and so must follow
its movements.
[Footnote 44: _l. c._, p. 4.]
The depression of the lower lid occurs simultaneously with the raising
of the eyeball by means of the _m. levator bulbi_, through the
contraction of the _m. depressor palpebrae inferioris_, which proceeds
from that muscle; this is easily understood, as they are but parts of
the same muscle.
II. MUSCLES OF THE FACE.
*11.* _M. intermaxillaris s. dilatator narium_ (Fig. 54 _im_).
*Dugès*, intermaxillaire, n. 1.--*Zenker*, intermaxillaris medius.
This small muscle lies in the space between the vertical processes of
the two premaxillary bones, and consists of obliquely-crossing fibres
arising from the one bone and inserted into the opposite one. It brings
together the processes of the intermaxillary bones, so that their upper
extremities approach each other. At the same time, the cartilaginous
nasal coverings or wings (_an_) diverge and the nares expand; hence we
may regard this muscle as corresponding to a _dilatator narium_.
[Illustration: Fig. 54.
Facial muscles of _Rana esculenta_.
_an_ Cartilaginous nasal alae.
_i_′ Vertical process of premaxillary bone.
_im_ M. intermaxillaris.
_ln_ M. lateralis narium.
_n_ Cartilaginous nose capsule.
]
*12.* _M. lateralis narium_ (Ecker), (Fig. 54 _ln_).
*Zenker*, _m. intermaxillaris lateralis_.--*Klein*, _m. nasalis
inferior_.--*Dugès*, sus-maxillo-pré-nasal, n. 2.
This small muscle occupies the space between the anterior portion
of the maxillary bone and the ascending process of the premaxillary
bone. It arises from the maxillary, and ascends obliquely forwards
to be inserted into the outer border of the ascending process of the
premaxillary bone. It is antagonistic to the foregoing.
A third muscle is described by Dugès as _sus-maxillo-post-nasal_, n.
3 (_nasalis externus_, Klein); according to him it passes from the
_proc. nasalis_ of the maxillary bone to the outer border of the nasal
opening, which it widens. According to Klein (_l. c._, p. 9), this
muscle in _R. temporaria_ runs to the upper border of the maxillary
bone beneath the lower eyelid, and is long and narrow. I have, however,
never been able to find muscular fibre in this situation.
III. MUSCLES OF THE LOWER JAW.
[Illustration: Fig. 55.
Muscles of the back and shoulder.
_c_ M. cucullaris.
_dm_,_dm_ M. depressor maxillae, arising from the fascia dorsalis.
On the right side it is cut through and reflected.
_fd_ Fascia dorsalis.
_fd_′ Same cut near the spinous processes.
_i_ M. infraspinatus.
_l.a_ M. levator anguli scapulae.
_ld_ M. latissimus dorsi.
_r_ M. retrahens scapulae.
_sc_ M. sternocleidomastoideus.
]
*13.* _M. depressor maxillae inferioris_, Carus, Zenker (Figs. 55,
56, 63 _d.m_.).
*Cuvier*, _l. c._, II, 141, _digastricus_.--*Dugès*,
sus-occipitodorso-angulaire, 32.
This is a strong, triangular muscle, wide above, pointed below. It
is placed between the head and the shoulder-blade. It arises in two
portions; the greater, from the _fascia dorsalis_ (_fd_), covers the
scapula, and passes inwards and backwards over the muscles of the back;
anteriorly it passes over the _m. temporalis_ and is attached to the
fronto-parietal and squamosal, being continued to the fascia of the
upper eyelid. The second part is smaller, and arises by fleshy fibres
from the postero-superior arm of the squamosal, and from the posterior
and inferior border of the cartilaginous tympanic ring. The two parts
unite and are inserted into the hinder angle of the lower jaw. Cuvier
correctly considers that only the anterior portion corresponds to the
_digastricus_, the posterior answering to the _m. cervico-maxillaris_
of snakes. It draws the lower jaw down and opens the mouth.
*14.* _M. temporalis_ (Figs. 49, 52, 56, 57 _t_).
*Cuvier*, _m. temporalis_, I, _l. c._, p. 138.--*Dugès*,
sous-rupéo-temporo-coronoidien.
This muscle, together with the _M. pterygoideus_, occupies the space
between the prootic and the eyeball; it arises by the greater part of
its fibres from the upper surface of the prootic; it passes, narrowing,
beneath the anterior arm of the squamosal, then over the pterygoid
bone, between this and the maxillary and quadrato-jugal, receiving
on the way other fibres which arise from the anterior border of the
inferior arm of the squamosal and from the anterior circumference of
the tympanic ring. The collected fibres end in a broad, flat tendon,
which is inserted into the inner surface of the so-called _proc.
coronoideus_.
[Illustration: Fig. 56.
Muscles of the lower jaw of _Rana esculenta_.
_d_ M. deltoideus.
_dm_ M. depressor maxillae, its origin where covering
the m. temporalis reflected at *.
_ld_ M. latissimus dorsi.
_m_ M. masseter.
_t_ M. temporalis, origin.
_t_′ Lower portion of same.
]
*15.* _M. pterygoideus_ (Figs. 49 _p_, 52, 57 _pt_).
*Cuvier*, _m. temporalis_, II, _l. c._--*Zenker*,
_m. massetericus_, _l. c._, p. 25.--*Dugès*,
pré-rupéo-pterygo-maxillaire, 31.
This is partly covered by the foregoing, and lies between it and
the eyeball. It arises at the inner wall of the orbit from the
fronto-parietal, and from that portion of the prootic which may be
regarded as the _ala magna_, above the _m. retractor bulbi_. The muscle
is broad, and compressed from before backwards: it runs downwards
covered by the _m. temporalis_, and soon passes into a long, thin
tendon (Fig. 57 _pt_), which is inserted, behind the _m. temporalis_
and immediately in front of the joint, into the inner surface of the
lower jaw.
*16.* _M. masseter_ (Figs. 56, 57 _m_).
*Dugès*, zygomato-maxillaire, n. 29.
Arises as a somewhat broad muscle from the horizontal process of the
quadrato-jugal and is inserted into the outer side of the lower jaw,
opposite the insertion of the _m. temporalis_.
[Illustration: Fig. 57.
Muscles of the lower jaw of _Rana esculenta_.
_dm_ M. depressor maxillae cut through and reflected.
_la_ M. levator anguli scapulae.
_l.d._ M. latiss. dorsi, cut through and reflected.
_m_ M. masseter.
_pt_ M. pterygoideus.
_s_ Scapula.
_s_′ Suprascapula.
_s.c._ M. sternocleidomastoideus.
_t t_ M. temporalis cut through and reflected.
]
*17.* _M. submaxillaris_ (Figs. 58, 59, 61 _sm_, _sm_′).
*Cuvier*, _m. mylo-hyoideus_, _l.c._, II, 536.--*Zenker*,
_mylo-sternoideus_, p. 25.--*Dugès*, sous-maxillaire, n. 15.
This muscle forms the floor of the mouth as does the _mylo-hyoideus_ in
man; it is, however, not inserted into the hyoid bone.
It arises--1. From the whole of the inner surface of the upper border
of the lower jaw[45], except near the angle (Fig. 58 _sm_);
[Footnote 45: A second origin from the lower border of the mandible,
described by Klein, is not to be found. The appearance is due to the
exit of vessels and nerves from the groove between the mandible and the
muscle.]
2. By a small portion (Figs. 58, 59, 61 _sm_′) near the skull, from
the cartilaginous anterior cornu of the hyoid-bone which projects from
the cartilaginous part of the prootic bone. This portion descends
along the cornu to unite with the other portion. The two together form
a membranous layer, the fibres of which run transversely and meet in
a band of connective tissue along the middle line, forming a kind of
_linea alba_. The sheath runs forwards to the most projecting part of
the lower jaw superficially to the _m. submentalis_. Slightly in front
of its posterior border the muscle is attached in its whole breadth to
the skin of the throat by a fine lamella of connective tissue, which
is not always complete. The posterior border of the muscle is attached
to a fascia, which passes between the deeper muscles and is attached
to these. It is known that this muscle plays an important part in the
movements of respiration and swallowing; but its precise action has not
yet been worked out.
*18.* _M. submentalis_ (Fig. 59 _smt_).
*Cuvier*, _transversus_, _l. c._, p. 588.--*Dugès*, 4,
sous-mentonnier.--*Zenker*, _m. lingualis_ (incorrectly brought
into connection with _m. hyoglossus_).
This small muscle lies in the anterior angle of the lower jaw between
the dentary bones. It consists of transverse fibres which pass from one
bone to the other. Below it is covered by the most anterior portion of
the _m. submaxillaris_.
[Illustration: Fig. 58.
Muscles of the throat, chest, and abdomen of _Rana esculenta_.
_sm_ M. submaxillaris.
_sm_′ Hinder portion of same arising from
the anterior cornu of the hyoid bone.
(For other references see page 68.) ]
Its action is to approximate the sides of the lower jaw: according to
Dugès (_l. c._, p. 123), it assists in closing the nostrils, by drawing
together the sides of the lower jaw and thus raising the premaxillae.
IV. MUSCLES OF THE HYOID BONE AND THE TONGUE.
*19.* _M. geniohyoideus_ (Figs. 59 _gh_, 60 _gh_).
*Cuvier*, IV, 1, 536.--*Dugès*, n. 16.--*Zenker*, p. 30.--*M. St.
Ange*, _l. c._, Pl. XXVI, f. 1, 13, p. 423.
Arises from the lower jaw in two portions, the one from near the middle
line above the _m. submentalis_, the other more externally from the
upper border of the lower jaw. The two parts unite to form a long,
flat muscle, which lies on the ventral surface of the body of the
hyoid bone, and divides posteriorly into two portions. One of these,
the median (Figs. 59, 60 _gh_″), is inserted into the inner border of
the posterior horn of the hyoid bone, and is here attached to a fascia
which covers the _m. hyoglossus_ from beneath. By the same fascia the
muscles of opposite sides are connected in the space between the two
posterior cornua. The lateral division (Figs. 59, 60 _gh_′) is attached
to the posterior cartilaginous process of the hyoid bone.
[Illustration: Fig. 59.
Muscles of the hyoid bone and the tongue of _Rana esculenta_.
The m. submaxillaris has been removed close to its insertion.
_cm_′ Origin of the hinder portion of same from the hyoid bone.
_gh_ M. geniohyoideus.
_gh_′ External portion of same.
_gh_″ Internal portion of same.
_H_ Body of hyoid bone.
_H_′ Anterior horn.
_hg_ M. hyoglossus.
_oh_ M. omohyoideus.
_ph_ Mm. petrohyoidei.
_sh_ M. sternohyoideus.
_sh_′ External origin of same.
_sh_″ Internal origin of same.
_sm_ M. submaxillaris.
_sm_′ Origin of hinder portion of same.
_smt_ M. submentalis.
]
*20.* _M. sternohyoideus_ (Figs. 59 60 _sh_).
*Cuvier*, IV, 1, 538 (_pubio-hyoideus_).--*Dugès*, n. 17,
sterno-xipho-hyoidien.--*Zenker*, p. 30.
This muscle forms the cervical part of the _m. rectus abdominis_
and is, in fact, a direct continuation of it. It arises by an inner
portion (Fig. 59 _sh_″) from the upper surface of the inner extremity
of the coracoid and from the xiphisternum, while the outer portion
(_sh_′) is an immediate continuation of the _m. rectus abdominis_,
which passes into this muscle at about the fifth _inscriptio tendinea_.
The muscle passes forwards on the upper surface of the coracoid
and of the clavicle, under the pericardium towards the hyoid bone;
here the muscle, hitherto horizontal, suddenly becomes (compare
Fig. 60) vertical, and passes between the two insertions of the _m.
geniohyoideus_, and is inserted for a considerable length into the
lower surface of the hyoid bone and the anterior extremity of the
posterior cornu.
[Illustration: Fig. 60.
Muscles of the tongue and of the hyoid bone of _Rana esculenta_, from
below.
_gh_ M. geniohyoideus.
_gh_′ External origin }
_gh_″ Internal origin } of same.
_H_ Body of hyoid.
_H_′ Anterior cornu.
_H_″ Posterior cornu.
_hg_ M. hyoglossus.
_hg_′ Hinder origin of same.
_oh_ M. omohyoideus.
_ph_. 1, 2, 3, 4, first, second, third, and fourth
m. petrohyoideus.
_sh_ M. sternohyoideus.
]
*21.* _M. omohyoideus_ (Figs. 59, 60 _oh_).
*Cuvier*, _l.c._, p. 539.--*Dugès*, n. 18, interscapulo-hyoidien ou
omohyoidien.-- *Zenker*, p. 31.--*M. St. Ange*, _l.c._
Arises from the anterior border of the bony scapula, and is inserted
into the outer part of the ventral surface of the body of the hyoid: it
is partially covered by the _m. sternohyoideus_.
*22.* _M. petrohyoideus anterior_ (Ecker), (Fig. 61 _ph_1).
*Dugès*, 10, rupéo-cérato-hyoidien.--*Zenker*, _m. petro-ceraus_?
p. 30.-- *Klein*, _basio-hyoideus_, _l.c._, p. 71.
A thin, flat muscle, narrow above, but broadening rapidly below,
which arising from the outer extremity of the prootic bone, partially
surrounds the pharynx below, into which some of its fibres are
inserted; it is attached to the ventral surface of the body of the
hyoid bone, near the lateral notch. The chief action of this muscle
appears to be that of a _m. constrictor pharyngis_.
*23, 24, 25.* _Mm. petrohyoidei posteriores_ (Ecker), (Figs. 61
_ph_ 2, 3, 4).
*Cuvier*, _mm. stylohyoidei_, _l. c._, p. 537.--*Dugès*, 20, 21,
22, masto-hyoideus (Fig. 4).--*Zenker*, _petro-hyoideus superior_
and _inferior_.--*Klein*, _stylo-hyoideus_, _l. c._, p. 18.
These are three long, thin muscles, which lie nearly parallel
to one another, and run from the prootic bone to the posterior
cornu of the hyoid bone. All three arise, covered by the _m.
sternocleidomastoideus_, from the lateral extremity of the prootic,
pass round the pharynx and are attached, the _m. petrohyoideus
posterior primus_ (Fig. 61 _ph_ 2) to the anterior extremity, the
_secundus_ (Fig. 61 _ph_ 3) to the middle; and the _tertius_ (Fig. 61
_ph_ 4) to the hinder extremity of the posterior horn of the hyoid bone.
*26.* _M. hyoglossus_ (Figs. 59, 60, 61 _hg_).
*Cuvier*, _l. c._, p. 588.--*Dugès*, 24, hyo-glosse.
Arises from the bony posterior extremity of the hinder process of the
hyoid bone (_hg_′). The muscles of the two sides pass forwards and
converge to the middle line, where they unite. The azygos muscle thus
formed runs forwards on the ventral surface of the hyoid bone, between
the _mm. geniohyoidei_, over the anterior border of the hyoid, and
passes into the tongue, where it turns backwards and runs to the tip.
(For action, see tongue.)
[Illustration: Fig. 61.
Muscles of the hyoid bone of _Rana esculenta_, seen from the right side
and below.
_H_′ Anterior cornu.
_H_″ Posterior cornu.
_hg_ M. hyoglossus.
_H H_ Body of hyoid bone.
_ph_ 1 M. petrohyoideus anterior.
_ph_ 2, 3, 4 Mm. petrohyoidei posteriores.
_sm_ M. submaxillaris.
_sm_′ Hinder portion of same.
]
*27.* _M. genioglossus._
*Cuvier*, _l. c._, p. 587.--*Meckel*, _l. c._, IV, 339.--*Dugès*,
23, genio-glosse.
Arises above the insertion of the _m. geniohyoideus_ on either side
near the middle line from the two anterior bones of the lower jaw. The
two origins quickly unite to form a thick, very firm muscular belly,
which in its course backwards rapidly thins, and is distributed by
numerous bundles; decussating with the fibres of the _m. hyoglossus_ at
an acute angle, it runs on to the anterior extremity of the tongue.
II. MUSCLES OF THE TRUNK.
I. MUSCLES OF THE ABDOMEN.
In the formation of the abdominal wall the following muscles take
part:--(1) _m. rectus abdominis_, (2) _m. obliquus externus_, (3)
_m. obliquus internus_, (4) the _portia abdominalis_ of the _m.
pectoralis_. Above, the _m. obliquus internus_ forms a kind of
*diaphragm*, partially separating the abdominal from the thoracic
cavity (p. 70).
*28.* _M. rectus abdominis_ (Fig. 62 _r_).
*Dugès*, pubio-thoracique, n. 52.
These muscles, situated on either side of the middle line of the
abdomen, are as a rule traversed by five notched _inscriptiones
tendineae_. Each muscle arises, by a narrow, strong tendon, from the
inferior border of the pubes, passes forwards, and quickly widening,
divides at the second _inscriptio tendinea_ (counting from behind) into
two portions.
(_a_) The Outer portion (Fig. 62 _r_) runs into the _portio
abdominalis_ of the _m. pectoralis_, and forms the greater lateral
division of that muscle.
(_b_) The Inner (_r_′) continues as the _m. rectus abdominis_ and
gradually narrows anteriorly. At the sternum some of the fibres (the
median) are inserted into the dorsal surface of the cartilaginous plate
of the xiphisternum, while the greater part of the muscle continues
forwards over the coracoid to become the _m. sternohyoideus_ at about
the fifth _inscriptio tendinea_ (p. 64).
*29.* _M. obliquus externus_ (Fig. 63 _oe_, _oe_′).
*Zenker*, _l. c._, p. 31, _m. obliquus_.--*Dugès*,
dorso-sous-abdominal, n. 54.
The _m. obliquus externus_ arises from--
(_a_) The aponeurosis covering the long muscles of the back, and by
this from the spinous processes. The anterior edge of the _m. obliquus
externus_ covers the posterior edge of the _m. latissimus dorsi_,
which arises from the inferior, ventral surface of the aponeurosis.
The aponeurosis also divides laterally into two parts, one of which,
the posterior, passes into the _obliquus externus_, while the anterior
forms the tendon of origin of the _depressor maxillae inf._ (_dm_)
(compare Fig. 66).
(_b_) A second, narrow portion, _portio omo-abdominalis_ (Fig. 63
_oe_′) (_m. xipho-adscapulaire_, Dugès, n. 62), arises from the
posterior border of the scapula by a thin tendon, and becomes broader
as it runs downwards and backwards, to join the anterior border of the
other and larger portion.
[Illustration: Fig. 62.
Muscles of the chest, throat, and belly of _Rana esculenta_.
_ch_ M. coraco-humeralis.
_d_ M. deltoideus.
_oi_ M. obliquus abdom. internus.
_oe_ M. obliq. abdom. externus.
_oe_′ Scapular portion of same.
_oh_ M. omohyoideus.
_p_′ Port. sternalis anterior of m. pectoralis.
_p_″ Port. sternalis posterior of same.
_p_‴ Port. abdominalis of same.
_r_ M. rectus abdominis.
_r_′ Inner portion of same.
_sh_ M. sternohyoideus.
_sm_ M. submaxillaris.
_sm_′ Hyoid origin of same.
_sr_ M. sternoradialis.
]
The whole muscle is attached by its most anterior fibres to the
cartilage of the xiphisternum, the rest passing into an aponeurosis
which, inseparably connected with the _inscriptiones tendineae_,
traverses the lower surface of the _m. rectus abdominalis_ to the
_linea alba_.
[Illustration: Fig. 63.
Muscles of trunk of _Rana esculenta_, from the right side.
_cd_ M. cutaneus femoris.
_d_ M. deltoideus.
_d.m._ M. depressor maxillae.
_i_ M. infraspinatus.
_ld_ M. latiss. dorsi.
_oe_ M. obliquus abdom. externus.
_oe_′ Scapular origin of same.
_ss_ M. subscapularis.
_t_ M. triceps brachii.
]
*30.* _M. obliquus internus_ (and _transversus_), (Figs. 64, 65
_oi_).
*Dugès*, ileo-transverso-sous-sternal, p. 53.--*Zenker*,
_transversus_, _l. c._, p. 31.--*Kuhl*, _transversus_, _l. c._,
p. 116.
This muscle corresponds with the combined _obliquus internus_ and
_transversus_, and has therefore been described either as the one or
the other, by various authors.
The fibres arise tendinously--
*a.* From the transverse processes of the vertebrae from the fourth
backwards, and from the fascia covering the _mm. intertransversarii_.
*b.* From the iliac bone, by a strong tendon from its upper border, and
by a few weaker fibres from its outer surface. The latter fibres are
covered by the former, and these end posteriorly in a sharp concave
border.
The muscular bundles diverge from these points, some running forwards,
some backwards; the former are only partially covered by the _portio
omo-abdominalis_ of the _m. obliquus externus_ (compare Figs. 62, 63),
in front of the anterior edge of that muscle. The posterior border of
the muscle is uncovered.
[Illustration: Fig. 64.
Second layer of abdominal muscles of _Rana esculenta_, from the right
side and below. The m. obliquus externus and the right anterior
extremity has been removed.
_dm_ M. depressor maxillae.
_hg_ M. hyoglossus.
_ld_ M. latissimus dorsi and infraspinatus.
_oi_ M. obliquus internus.
_oi_′ Insertion of third portion of same.
_oi_″ Second portion inserted into the pharynx.
_pc_ Pericardium.
_ph^4._ M. petrohyoideus quartus.
_r_ M. rectus abdominis.
_ss_ M. subscapularis.
]
The insertions of the muscle are very various, and as a consequence
very various functions are accomplished by it.
*a.* The most anterior part of the muscle (Fig. 65 _oi_‴), the fibres
of which run forwards, is attached--
1. Partly to the xiphisternum and the coracoid.
2. A second portion, _viz._ that arising from the transverse processes
of the fourth vertebra (Fig. 64 _oi_″), surrounds the pharynx like a
diaphragm (Fig. 65 _oe_), and is attached to its side as far as the
dorsal aspect (Fig. 65 _oi_′). This portion is lightly separated from
the following.
3. A third portion, placed behind the preceding, runs from the pharynx
over the pericardium (Fig. 64 _pc_), and is attached to this nearly
as far as the middle line (Figs. 64 _oi_′ and 65 _oi_″), resting on
the sternum, the _m. rectus_ and _m. sterno-hyoideus_. The lines of
insertion of the muscles of opposite sides form an angle, open in
front. In the thin borders of this portion the muscular bundles lie
almost entirely in simple layers, and they are therefore well adapted
for microscopical purposes.
*b.* The middle and posterior portions of the muscle pass downwards
and slightly backwards, towards the outer border of the _m. rectus_;
there they pass into a tendon which, for the most part, runs on the
upper surface of the _rectus_ to the _linea alba_.
II. MUSCLES OF THE BACK.
The muscles of the back are covered by a fascia, the *fascia dorsalis*
(Fig. 66 _fd_), attached to the spinous processes of the vertebrae.
Anteriorly, where it covers the _m. temporalis_, it is attached to the
fronto-parietal and squamosal bones, posteriorly to the superior border
of the iliac bones and the extremity of the urostyle. The posterior
part, which covers the origins of the _m. longissimus dorsi_, of the
_m. coccygeo-iliacus_, and of the _coccygeo-lumbaris_, is especially
strong. From the anterior part several muscles arise laterally, viz.
a portion of the _m. obliquus abdominalis externus_, of the _m.
latissimus dorsi_, and of the _m. depressor maxillae inferioris_. In
the uppermost layer, immediately covered by the _fascia dorsalis_, lie
the _m. cucullaris_, the _m. retrahens scapulae_, the _m. latissimus
dorsi_ arising from the fascia itself, and the scapula with its
muscles; then come the long muscles of the back; and in the third and
deepest layer the short muscles of the back.
[Illustration: Fig. 65.
M. obliquus internus, showing its attachments superiorly.
_h_ Xiphisternum.
_oe_ Oesophagus.
_oi_ M. obliquus internus.
_oi_′ Fibres of m. obliq. int., which are inserted
into the oesophagus.
_oi_″ _oi_‴ Fibres of same, which are attached to
coracoid and xiphisternum.
_p_ Pericardium.
_r_ M. rectus abdominis.
]
The individual muscles are as follows:--
A. _LIMB MUSCLES OF THE BACK_ (for moving the shoulder-girdle and arm).
*31.* _M. cucullaris_ (Fig. 66 _c_).
*Cuvier*, _angularis_.--*Dugès*, n. 38, sous-occipito
adscapulaire.--*Zenker*, _levator scapulae sublimis_.
In order to see this muscle, it is necessary to separate the _fascia
dorsalis_ from the spines of the vertebrae and to turn it back with
the _m. depressor maxillae inf._ arising from it. It is then seen to
rise from the posterior surface of the exoccipital as far as the middle
line; the muscles of the two sides run backwards, diverging each from
the other, so as to form an angle, and are then attached on each side
to the anterior superior angle of the suprascapula at its under surface
and median border.
Cuvier considers this muscle as the analogue of the _m. levator anguli
scapulae_. Dugès and Meckel consider it to be the anterior part of the
_m. cucullaris_, the former thinking the posterior part of the muscle
to be the _m. rhomboideus_. I cannot agree with these opinions, and I
regard the muscle as simply representing the _m. cucullaris_ of man
(Ecker).
*32.* _M. latissimus dorsi_ (Figs. 56, 66 _ld_).
*Dugès*, n. 66, lombo-huméral.--*Zenker*, _depressor brachii_.
This thin, triangular muscle arises from the ventral surface of the
_fascia dorsalis_, and is posteriorly covered in part by the anterior
border of the _m. obliquus abdominis externus_. The muscle becomes
narrower towards the sides, and passes into a flat tendon, which
blends with that of the _m. infraspinatus_, and is attached to the
outer surface of the _crista deltoidea_ of the humerus by a triangular
expansion.
*33.* _M. retrahens scapulae_ (Ecker), (Fig. 66 _r_).
*Dugès*, n. 59, lombo-adscapulaire.--*Klein*, _m. rhomboideus_, _l.
c._, p. 26.--*Zenker*, _omoplateus rectus_? p. 37, _l. c._--*Kuhl*,
_l. c._, 124, _retrahens rhomboideus_.
[Illustration: Fig. 66.
Muscles of the back and shoulder-blade.
_c_ M. cucullaris.
_dm_ M. depressor maxillae arising from the fascia dorsalis,
cut through and reflected on the right side.
_fd_ Fascia dorsalis.
_fd_′ Same cut through at the spines.
_i_ M. infraspinatus.
_l.a_ M. levator anguli scapulae.
_ld_ M. Latissimus dorsi.
_r_ M. retrahens scapulae.
_sc_ M. sternocleidomastoideus.
]
This flat, oblong muscle arises from the transverse process of
the fourth vertebra, and is connected with the third tendinous
inscription (counting from before) of the _m. longiss. dorsi_.
Posteriorly its origin forms a convex border, whence it runs forwards
and to the side; it is inserted into the ventral surface of the
suprascapula, near its inner border. This muscle lies near the _m.
serratus_ or _transv. scap. tertius_ (Fig. 68 _ts_″), and has an
analogous position. It would, therefore, possibly be more correct
to regard it also as a _m. serratus_. It arises from parts which
represent ribs, and is inserted into the scapula. It has, at any
rate, no analogy to the _m. cucullaris_, with which Dugès connects
it, nor with the _m. rhomboideus_, which Klein holds it to be, as it
does not arise from spinous processes.
B. _LONG MUSCLES OF THE BACK._
*34.* _M. extensor dorsi communis_ (Fig. 67 _lg.d._).
*Dugès*, n. 33–40, masse des muscles surspinaux devisée en
huit faisceaux principaux: 1. vertebro-sus-occipital, 2–5.
transverso-spinaux, 6. transverso-coccyg., 7. sacro-coccygien,
8. ileo-coccygien. The muscles 1–7 form the lombo-costal, 8 the
ischicoccyg., Cuv.--*Zenker*, _m. sacrolumbaris_.--*Klein*,
_longiss. dorsi_, _coccygeo-lumb._, _coccyg.-iliac_.
This muscular mass is covered by the _fascia dorsalis_, the _m.
cucullaris_ and _retrahens scapula_, and the suprascapula: it
corresponds with (1) the _m. ileo-costalis_ and _longissimus dorsi_,
_dorsi_ and _cervicis_ (Henle); (2) the _semispinalis_ and _spinalis_
(Henle).
The following separate portions may be made out:--
*35.* (1) _M. longiss. dorsi_ (Fig. 67 _lg.d._).
This muscle arises from the most anterior part of the urostyle, runs
forwards near the middle line, separated from the muscle of the
opposite side by the spinous processes of the vertebrae. The inner
portion passes over the posterior spinous processes without being
connected with them, as far as the fifth, it is then inserted into
the succeeding spines as far as the exoccipital bone. The lateral
portion runs outwards and forwards to be attached to the transverse
processes and oblique processes of all the vertebrae, from the sixth
forwards, while accessory muscular slips arise from the transverse
processes and from the anterior spinous processes which, merging in
the general muscle-mass, are inserted with this into the occiput.
The muscle is subdivided by a series of wavy, tendinous partitions
(Fig. 67), which arise from the transverse processes, and traverse
the muscle in planes, the upper surfaces of which are directed
upwards and forwards. This arrangement of the muscle indicates
its relation with the lateral trunk muscles of fish and fish-like
amphibians.
*36.* (2) _M. coccygeo-sacralis_ (Fig. 67 _c.l._).
This muscle is partially covered by the preceding, it arises
from the lateral surfaces of the anterior half of the urostyle;
from this origin the fibres pass forwards and outwards to be
inserted in two portions, the anterior set into the arch and the
posterior set into the transverse process of the last vertebra. The
former may be regarded as _m. intercruralis_, the latter as _m.
intertransversarius_.
*37.* (3) _M. coccygeo-iliacus_ (Fig. 67 _c.i._).
This muscle arises from nearly the whole length of the lateral
surface of the urostyle, the anterior portion being concealed by
the preceding muscle. The fibres pass outwards and forwards to be
inserted into the anterior two-thirds of the inner surface of the
ilium.
[Illustration: Fig. 67.
Muscles of the back and pelvic girdle of _Rana esculenta_.
_c.i._ M. coccygeo-iliacus.
_c.l._ M. coccygeo-sacralis.
_g.l._ M. glutaeus.
_i_ MM. intertransversarii.
_i′_ MM. intercrurales.
_i.c.i._ M. intertransv. capitis inferior.
_i.c.s._ M. intertr. cap. sup.
_il._ M. ilio-lumbaris.
_lg.d._ M. longissimus dorsi.
_o.i._ M. obliq. internus.
_t_ M. temporalis.
]
*38.* _M. ilio-lumbaris_ (Klein), (Fig. 67 _il._).
*Dugès, n.* 51, transverso-iliaque.--*Cuvier*, *Zenker*, etc.,
_quadr. lumborum_.
Evidently represents the _quadratus lumborum_ of human anatomy;
it takes its origin from the anterior extremity of the ilium, and
runs forwards to be inserted into the transverse processes of the
vertebrae from the seventh to the fourth.
C. _SHORT MUSCLES OF THE BACK._
*39.* _M. intertransversarius capitis superior_ (Ecker), (Fig. 67
_i.c.s._).
*Dugès*, n. 41, ex-occipito-transversaire sup.
A small muscle arising from the prootic: it lies above the _levator
anguli scapulae_, and is inserted into the transverse process of the
second vertebra.
*40.* _M. intertransversarius capitis inferior_ (Fig. 67 _i.c.i._).
*Dugès*, n. 42, ex-occipito-transv. inf.
This muscle lies on the ventral surface of the preceding one, but is
easily separable from it; it arises from the angle of the prootic and
is inserted, together with the preceding muscle, into the transverse
process of the third vertebra. The _n. vagus_ passes outwards between
these two muscles.
*41.* _MM. intertransversarii dorsi_ (Fig. 67 _i_).
*Dugès*, n. 43 to 50, intertransversaires.
Seven small muscles, placed between adjacent transverse processes of
the vertebrae; from the second to the last, in continuity with the
muscles last mentioned.
*42.* _MM. intercrurales_ (Ecker), (Fig. 67 _i_′).
*Klein*, p. 29, interspinales, interobliqui.
Those muscular fibres found between the arches of adjacent vertebrae
are so named. On account of the shortness of the spinous processes
they can scarcely be named _m. interspinales_.
III. MUSCLES OF THE ANTERIOR EXTREMITY.
I. MUSCLES OF THE SHOULDER-GIRDLE.
A. _DORSAL MUSCLES OF THE SHOULDER-BLADE_.
(I.) Muscles arising from the head or trunk, and inserted into
the scapulae, which they act upon primarily, and upon the
shoulder-girdles secondarily.
Some of these muscles, such as _m. cucullaris_ and _retrahens_,
are situated on the back, and have already been described with
the muscles of that region. Others are attached partly to the
under-surfaces of the scapulae and are only visible from below; they
are best seen in such a preparation as is shown in Fig. 68, made by
cutting through the sternum in the middle line, and reflecting each
half outwards.
(*a*) _Muscles which arise from the skull_.
*43.* _M. levator anguli scapulae_ (Fig. 68 _la_).
*Dugès*, sous-occipito-adscapulaire, n. 60.--*Zenker*, _protractor
scapulae_, Pl. I, Fig. 5.--*Cuvier*, Leçons I, p. 379, describes
this muscle as part of the _m. serratus anticus magnus_.
A fairly strong muscle, which has a broad origin from the prootic
and exoccipital bones as far as the _foramen magnum_, a few fibres
are also attached to the lateral portions of the parasphenoid. The
fibres run backwards and outwards, first in a frontal plane and then
in a sagittal plane, to be inserted into the under surface of the
suprascapula near the posterior border, where it encloses the hinder
border of the _m. interscapularis_.
Its action is to draw the shoulders forwards and inwards, or the head
downwards.
*44.* _M. sternocleidomastoideus_ (Fig. 68 _sc_).
*Dugès*, scapulo-mastoidien, n. 65.--*Cuvier*,
sterno-mastoidien.--*Zenker*, _protractor scapulae_, Pl. I, Fig. 5,
1.
A narrow muscle placed in front of and externally to the preceding
muscle; its general direction resembles that of the _m. levator ang.
scap_.
The fibres arise from the most external part of the prootic and
from the hindermost part of the squamosal, under cover of the
_m. digastricus maxillae_, and from the hinder portion of the
cartilaginous tympanic ring. Covered by these muscles, it passes
backwards and downwards to be inserted into the concavity of the
anterior border of the scapula; externally to the origin of the
deltoid.
The action of this muscle is to draw the shoulder forwards and
towards the middle line, or to bend the head downwards.
*45.* _M. protrahens scapulae_ (Fig. 68 _ps_).
*Dugès*, *Zenker*, _protractor acromii_, Pl. I, Fig. 5, 3.
This muscle lies to the outer side of the _rectus capitis inferior_:
it arises from the prootic, and runs backwards and outwards upon the
_levator anguli scapulae_, to be inserted into the scapula.
It pulls the scapula forwards.
(*b*) _Muscles which arise from the vertebrae._
*46.* _M. transverso-scapularis major_ (Ecker), (Fig. 68 _ts_).
*Dugès*, transverso-interscapulaire, n. 63.--*Cuvier*,
_l. c._, p. 380, probably regarded as a portion of the
_serratus_.--*Zenker*, Pl. I, Fig. 5, 3; _depressor acromii_,
Pl. II, Fig. 3, 15.--*Klein*, _depressor scapulae_.
This muscle arises by tendon from the cartilage of the transverse
process of the fourth vertebra and by a slip from the cartilage of
the transverse process of the third vertebra. Diminishing in size,
the muscle passes outwards, forwards, and upwards to be inserted
into the posterior border of the scapula, opposite the insertion
of the _m. sternocleidomastoideus_. It draws the shoulder inwards,
backwards, and downwards.
*47.* _M. transverso-scapularis minor_ (Ecker), (Fig. 68 _ts_′).
*Dugès*, transverso-adscapulaire, n. 61.--*Cuvier*, regarded as
part of the _serratus_.--*Zenker*, Pl. I, Fig. 5, 7, _detractor
scapulae_.
This is much shorter than the muscle just described; it arises under
cover of the _m. levator scapulae_, from the transverse process of
the third vertebra in front of the _transverso-scapularis major_; and
runs outwards and forwards to be inserted into the ventral surface of
the cartilage of the scapula. The action of the muscle is to draw the
shoulder inwards, backwards, and outwards. Dugès regards this muscle
as a portion of the _serratus anticus magnus_, the remainder of which
he considers is to be found in the _portio scapularis_ of the _m.
obliquus externus_ (xipho-adscapulaire, Dugès, n. 62).
[Illustration: Fig. 68.
Muscles of the shoulder, from below; the sternum has been cut through
and the sides drawn apart.
_d_ Deltoideus.
_is_ Interscapularis.
_it_ Intertransversarii.
_la_ Lev. anguli scapulae.
_ps_ Protrahens scapulae.
_sc_ Sternocleidomastoideus.
_ss_ Subscapularis.
_ts_ Transverso-scap. major.
_ts_′ Transverso-scap. minor.
_ts_″ Transverso-scap. tertius.
]
*48.* _M. transverso-scapularis tertius s. serratus_ (Ecker),
(Fig. 68 _ts_″).
This is larger than the muscle just described; arising by a broad
and flat origin from the transverse processes of third and fourth
vertebrae, it runs upwards and inwards to be inserted into the
ventral surface of the cartilaginous scapula near its inner border.
In position, course, and action the muscle most nearly represents the
_m. serratus anticus_ of human anatomy.
(II.) Muscles on the scapula, that is, arising from the scapula and
inserted into the scapula or humerus.
(*a*) _Muscles on the deeper surface._
*49.* _M. interscapularis_ (Fig. 69 _i.s._).
*Dugès*, interscapulaire, n. 64.
[Illustration: Fig. 69.
Muscles of right shoulder and upper arm. The coracoids (_co_) and
the clavicles (_cl_) have been drawn apart after cutting through the
sternum.
_c.h._ M. coraco-humeralis.
_cl_ Clavicle.
_c.o._ Coracoid.
_d_ M. deltoideus.
_d_′ Clavicular portion of m. deltoideus.
_i_ M. infraspinatus.
_i.s._ M. interscapularis.
_l.a._ M. levator anguli scapulae.
_l.d._ M. latissimus dorsi.
_p_′ Sternal portion of m. deltoideus.
_p_″ Anterior sternal portion of the m. pectoralis.
_p_‴ Posterior sternal portion of the m. pectoralis.
_s_ Scapula.
_s.r._ M. sternoradialis.
_t.r._ M. triceps brachii.
]
One end of this muscle is tendinous, and is attached to the outer
extremity of the suprascapula; from this the muscle, becoming fleshy
and narrower, runs towards the middle line to become attached to
the ridge on the ventral surface of the scapula, from which the _m.
deltoideus_ and the _m. subscapularis_ arise, and between which it
passes. It approximates the scapula and suprascapula and lessens the
angle between them.
*50.* _M. subscapularis_ (Fig. 70 _ss_).
*Dugès*, sous-scapulo huméral, n. 72.
This muscle is situated on the upper or visceral surface of the
scapula. It arises from a bony ridge found on the upper surface of
the coracoid and of the _proc. coracoideus_ of the scapula. The
muscle runs outwards and is inserted, after widening, into the inner
surface of the _crista deltoidea_ of the humerus; it is antagonistic
to the deltoid, and draws the raised arm backwards and towards the
trunk.
[Illustration: Fig. 70.
Right shoulder, from below, arm strongly abducted.
_cl_ Clavicle.
_co_ Coracoid.
_d_ Deltoideus.
_d_′ Clavicular portion of deltoid.
_h_ Humerus.
_ss_ Subscapular muscle.
]
(*b*) _Muscles on the superficial surface._
*51.* _M. infraspinatus_ (Fig. 57, between _ld_ and _dm_, Fig. 71
_i_).
*Dugès*, adscapulo-huméral, n. 67.
The _m. infraspinatus_ represents the _m. infraspinatus_, _teres
major_ and _minor_ of human anatomy. It is of triangular form, with
the broad base directed inwards; it arises from the whole of the
upper surface of the suprascapula except along the inner border which
is formed of hyaline cartilage alone: from this origin the fibres
converge outwards to a flat tendon which unites with that of the _m.
latissimus dorsi_ to be inserted into the _crista deltoidea humeri_,
by means of a thin, triangular, tendinous expansion.
[Illustration: Fig. 71.
Muscles of the back and shoulder.
_c_ M. cucullaris.
_dm_ M. depressor maxillae.
_fd_ Fascia dorsalis.
_fd_′ Fascia dorsalis reflected.
_i_ M. infraspinatus.
_l.a_ M. levator anguli scapulae.
_ld_ M. latissimus dorsi.
_r_ M. retrahens scapulae.
_sc_ M. sternocleidomastoideus.
]
*General arrangement of the muscles of the shoulder-blade.*
The muscles attached to the scapula and suprascapula are:
1. Muscles of the back (_m. cucullaris_ and _m. retrahens scap._).
2. Muscles of the neck (_m. omohyoideus_).
3. Muscles of the abdomen (_portio scapularis_ of the _m. obliquus
externus_).
4. True shoulder muscles (_m. levator anguli scapulae_; _m.
sternocleidomastoideus_; _m. protrahens scapulae_; _mm.
transverso-scapularis major_, _minor_, and _tertius s. serratus_; _m.
interscapularis_; _m. subscapularis_; and the long head of the _m.
triceps_).
*From above* the following are visible: _m. cucullaris_, a portion of
the _m. subscapularis_, and the _transverso-scapularis maior_.
*From below* (after cutting through and drawing aside the
two halves of the sternum) may be seen: the _omohyoideus_,
_sternocleidomastoideus_, _levator anguli scapulae_, _protrahens
scapulae_, _transverso-scapularis minor_ and _tertius_,
_interscapularis_ and _subscapularis_.
B. _VENTRAL MUSCLES OF THE SHOULDER (PECTORAL MUSCLES)_
These arise from the sternum or shoulder-girdle and are inserted
either into the humerus or into the radio-ulnar.
*52.* _M. pectoralis_ (Fig. 72).
This is placed on the ventral surface of the shoulder-girdle and
consists of the following parts:
(α) _Portio sternalis anterior_ (Ecker), (Figs. 72, 73 _p_′).
*Dugès*, clavi-huméral, n. 70 (port. clavic. du grand pectoral).
This is the anterior portion of the _m. pectoralis_, it arises from
the sternum proper and the epicoracoids. Broad at the origin, it
becomes narrower as it runs outwards into a tendon attached to the
_crista deltoidea humeri_.
(β) _Portio sternalis posterior_ (Ecker), (Figs. 72, 73 _p_″).
*Dugès*, sterno-huméral, n. 71 (port. sternal du grand
pectoral).--*Klein*, _humero-sternalis_.
This muscle is placed immediately behind the _portio sternalis
anterior_, it has a somewhat broad origin from the sternum and
xiphisternum; the muscle runs outwards and slightly forwards to be
inserted into the groove beside the _crista deltoidea humeri_. The
tendon of the _m. sterno-radialis_ passes between these two portions
of the _m. pectoralis_.
(γ) _Portio abdominalis_ (Figs. 72, 73 _p_‴).
*Dugès*, abdomino-huméral, n. 69 (port. costal du grand
pectoral).--*Zenker*, _brachio-abdominalis_.--*Klein*,
_humero-abdominalis_.
[Illustration: Fig. 72.
Muscles of the chest, throat, and belly of _Rana esculenta_.
_ch_ M. coraco-humeralis.
_d_ M. deltoideus.
_oi_ M. obliquus abdom. internus.
_oe_ M. obliq. abdom. externus.
_oe_′ Scapular portion of same.
_oh_ M. omohyoideus.
_p_′ Port. sternalis anterior to m. pectoralis.
_p_″ Port. sternalis posterior to same.
_p_‴ Port. abdominalis of same.
_r_ M. rectus abdominis.
_r_′ Inner portion of same.
_sh_ M. sternohyoideus.
_sm_ M. submaxillaris.
_sm_′ Hyoid origin of same.
_sr_ M. sternoradialis.
]
This portion represents that part of _m. pectoralis major_ of
human anatomy which arises from the costal cartilages, and more
particularly that part which is connected with the aponeurosis of
the _m. obliquus abdominis externus_. The muscle arises (1) from
the _m. rectus abdominis_ (Fig. 72 _r_), that is, it forms a direct
continuation of the outer portion of this muscle; (2) the inner,
smaller part arises from the superficial surface of the aponeurosis
of the _m. obliquus abdominis_. The muscle becomes narrower as it
courses outwards and forwards, the outer fibres being longer and more
oblique than the inner. The action of this muscle will necessarily
vary according to the part or parts which are brought into action;
speaking generally, the anterior extremities will be drawn downwards
and towards each other.
*53.* _M. coraco-humeralis_ (Dugès), (Figs. 72, 73 _c.h._).
*Dugès*, n. 72.--*Klein*, _adductor humeri_.
A long, narrow muscle, lying upon the posterior border of the
coracoid and the lowest part of the _m. subscapularis_. By its
position it corresponds most nearly with the _m. pectoralis minor_,
although its insertion does not. It has a narrow origin from the
coracoid near the sternum, whence it courses outwards, under cover
of the _port. sternalis anterior_ and _posterior_ of the _m.
pectoralis_, to be inserted into the middle of the humerus between
the deltoid and internal head of the triceps. It draws the limb
towards the trunk.
*54.* _M. sternoradialis_ (Cuvier), (Figs. 72, 73 _s.r._).
*Dugès*, pré-sterno-clavi-radial, n. 74.
This muscle evidently represents the biceps of man, it lies in front
of the _portio sternalis anterior_ of the _m. pectoralis_, its hinder
border being under cover of the latter muscle. It takes origin from
the episternum, omosternum, and the epicoracoid; from this broad
origin the fibres converge while coursing backwards and outwards
to be attached to a strong tendon. This tendon plays in a groove
along the _crista deltoidea_, and is held in position by tendinous
bands arising from the insertion of the _m. pectoralis_; it then
pierces the lower portion of the muscular belly of the deltoid, and
is inserted into the anterior extremity of the radial side of the
radio-ulnar. The muscle is a powerful flexor of the forearm.
*55.* _M. deltoideus_ (Figs. 70, 72, 73 _d_).
*Dugès*, pré-sterno-scapulo-huméral, n. 68.
It is placed in front of and external to the _m. sternoradialis_, and
represents both the _m. deltoideus_ and _supraspinatus_ of man. The
muscle has two points of origin:--
(*a*) _Portio scapularis_, the larger, external portion is attached
to the outer end of the clavicle, and to the anterior process of the
precoracoid, but it arises chiefly from the dorsal surface of the
scapula (from the same ridge as the _m. subscapularis_), and lastly
from the anterior border and ventral surface of the scapula. The
fibres pass outwards over the shoulder-joint.
[Illustration: Fig. 73.
Muscle of right shoulder and upper arm. The coracoids (_c.o._) and
the clavicles (_cl_) have been drawn asunder after cutting through
the sternum.
_c.h._ M. coraco-humeralis.
_cl_ Clavicle.
_c.o._ Coracoid.
_d_ M. deltoideus.
_d_′ Clavicular portion of m. deltoideus.
_i_ M. infraspinatus.
_i.s._ M. interscapularis.
_l.a._ M. levator anguli scapulae.
_l.d._ M. latissimus dorsi.
_p_′ Sternal portion of m. deltoideus.
_p_″ Anterior sternal portion of the m. pectoralis.
_p_‴ Posterior sternal portion of the m. pectoralis.
_s_ Scapula.
_s.r._ M. sternoradialis.
_t.r._ M. triceps brachii.
]
(*b*) _Pars clavicularis_ (_musc. cleido-humeralis_, Klein) arises
from the inner extremity of the clavicle and from the omosternum and
joins the _portio scapularis_.
The muscle is inserted into the humerus, the under part of the
_portio scapularis_ being attached to the upper portion of the
_crista deltoidea_; the outer fibres of this part, together with
those of the _pars clavicularis_, are attached to the extremity of
the _crista deltoidea_ and to the inner surface of the humerus as
far as the distal extremity; just before its insertion the muscle is
pierced by the tendon of the _m. sternoradialis_. The deltoid draws
the limb forwards.
II. MUSCLES OF THE FORE-LIMB.
A. _MUSCLES OF THE ARM._
_M. sternoradialis (biceps)._ See page 82.
*56.* _M. triceps brachii_ (Fig. 73 _t.r._).
*Dugès*, scapulo-huméro-olecranien, n. 75.--*Capes*, *Zenker*, _m.
anconaeus_.
This muscle lies on the upper or dorsal surface of the arm, and
has relations similar to those of the corresponding muscle in man.
The long head arises from the posterior border of the scapula at
the upper border of the glenoid cavity, and is here attached to
the capsule of the joint; the inner head arises from the upper and
inner surfaces of the anterior half of the humerus as far as the
extremity; the outer head arises from the outer surface of the
humerus. Additional fibres, which may be regarded as a fourth origin
(_m. subanconaeus_), arise from the upper surface of the hinder
half of the humerus. The fibres from these several origins unite
to form a strong muscle, which covers the upper, inner, and outer
surfaces of the bone, and then passes into a tendon. This tendon is
attached to the capsule of the elbow-joint and inserted into the
proximal extremity of the radio-ulnar. A cartilage, representing the
olecranon, is found in the capsule at the point of attachment of the
tendon.
B. _MUSCLES OF THE FOREARM._
(I.) Muscles of the flexor surface.
The muscles of this surface are arranged in two groups, so as to
form, at the elbow-joint, a triangular depression (_plica cubiti_),
into which the tendon of the _m. sternoradialis_ sinks.
A. Muscles of the Inner Group.
*57.* _M. flexor carpi I s. radialis_ (Fig. 74 _Fc_).
*Dugès*, sous-huméro-carpien, n. 83.
This represents either the _flexor carpi radialis longior_ or
_radialis brevior_ of man; it has a broad origin from the inner
border of the humerus above the epicondylus medialis. It becomes
narrower as it passes downwards to be inserted by a tendon into the
_os semilunare_ and _naviculare_. The muscle is much stronger in
males than in females, and the crest from which it takes origin is
correspondingly larger in the former sex (p. 42). Tendinous fibres
connect it with the following muscles:--
*58.* _M. flexor carpi II s. ulnaris_ (Fig. 74 _Fc_′).
*Dugès*, epitrochlo-carpien, n. 84.
This muscle represents the _flexor carpi ulnaris_ or _ulnaris
anterior_, and is close to the inner side of the foregoing. It arises
from the _epicondylus medialis_, being connected by fibres with the
_flexor digitorum communis_, and is inserted into the _os naviculare_.
[Illustration: Fig. 74.
Muscles of the right arm of _Rana esculenta_.
_ed_ M. extens. digitorum communis.
_ei_ M. abductor digiti II longus.
_Fa_′ M. flexor antibrachii lateralis superficialis.
_Fc_ M. flexor carpi radial.
_Fc_′ M. flexor carpi ulnar.
_Fd_ M. flexor digitorum communis.
_sr_ Tendon of the M. sternoradialis.
]
*59.* _M. flexor digitorum communis_ (Figs. 75, 76, 77 _Fd_).
*Dugès*, epitrochlo-sous-phalangettien, n. 118.
This muscle lies most internally, and corresponds to the _m. flexor
digitorum sublimis_ of man. It arises in common with the foregoing
muscle from the _epicondylus medialis_, and runs downwards to the palm
of the hand. At its entrance into this it diminishes and passes into
the flat _aponeurosis palmaris_. (See hand, B.)
*60.* _M. flexor antibrachii medialis_ (Ecker), (Fig. 75 _Fa_).
*Dugès*, epitrochlo-sous-radial, n. 79. (Frequently described as the
_pronator rotundus_, a description which cannot be retained, as the
implied movement does not occur in the frog.--Ecker.)
This muscle lies deeply on the inner side of the forearm, covered by
the _flexores carpi_; it arises tendinously from the _epicondylus
medialis_ and is inserted into the inner surface of the radial side of
the radio-ulnar as far as the inferior articular extremity.
*61.* _M. flexor antibrachii lateralis superficialis_ (Ecker),
(Figs. 74, 75 _Fa_′).
*Dugès*, premier ex-huméro-radial, n. 76. (Usually described as
_supinator longus_, this, for reasons similar to those in the case
of _m. flexor antibrachii medialis_, cannot be retained.)
The situation of this muscle corresponds with that of the _supinator
longus_ of man; it lies to the outer side of the tendon of the _m.
sternoradialis_, and arises by two heads, the one, above from the
outer edge of the humerus, the other deeper from the _epicondylus
lateralis_. They unite and pass into a tendon which, running over the
lower articular extremity of the radio-ulnar, is partly attached to
the carpus and partly connected with the tendon of the _m. extensor
digiti II proprius longus_. From its position and insertion, this
muscle evidently flexes the forearm and extends the hand.
[Illustration: Fig. 75.
Muscles of the right arm of _Rana esculenta_, deep layer.
_ed_ Extensor digit. communis.
_Fa_ Flexor antibrachii medialis.
_Fa_′ Flexor antibrachii lat. superficialis.
_Fa_″ Flexor antibr. lat. profundus.
_Fc_ Flexor carpi radialis.
_Fc_′ Flexor carpi ulnaris.
_Fd_ Flexor digitorum communis.
]
*62.* _M. flexor antibrachii lateralis profundus_ (Ecker), (Fig. 75
_Fa_″).
*Dugès*, epicondylo-sus-radial, n. 78.--*Klein*, _flexor
antibrachii_. (_Supinat. brevis_ autt.)
This muscle arises under cover of the foregoing, from the
_epicondylus lateralis_ of the outer surface of the humerus, it
becomes broader and is inserted into the whole length of the lower
(volar) ridge of the radio-ulnar. It is a powerful flexor of the
forearm.
(II.) Muscles of the extensor surface.
*63.* _M. extensor digitorum communis longus_ (Fig. 75 _ed_).
*Dugès*, huméro-sus-digital, n. 95.
This muscle lies on the outer border of the forearm; it arises
in common with the short head of the _flexor antibr. lateralis
superficialis_ from the _epicondylus lateralis_, and from the surface
above it; it runs downwards along the outer side of the forearm,
in order to pass into an aponeurosis on the back of the hand,
which expands upon the third, fourth, and fifth fingers, and ends
between them in a free concave border. This aponeurotic expansion is
connected with the tendons of the _extensor brevis digitorum_.
*63*.* _M. abductor digiti II_ (_i. e. pollicis_) _longus_ (Fig. 74
_ei_).
**Dugès*, cubito-métacarpien, n. 87.
This muscle lies between the foregoing and the _flexor antibrachii
lateralis superficialis_, and appears superficially in the interval
between them. It arises from the lateral surface of the radio-ulnar,
and runs obliquely over the _m. flexor antibrachii lateralis
profundus_ and the hinder extremity of the radio-ulnar towards the
second finger into the metacarpal bones of which it is inserted.
*64.* _M. extensor carpi ulnaris s. ulnaris post._ (Fig. 76 _ec_).
*Dugès*, epicondylo-sous-carpien, n. 85.--*Klein*, _abductor carpi
internus_.
This muscle has a somewhat narrow origin from the _epicondylus
lateralis_; during its course through the forearm, where it lies
between the _mm. anconaei_ on the one side and the _extensor
digitorum communi_ on the other, it becomes broader and is inserted
into the outer surface of the carpus in the following manner. By
one tendinous slip it is attached to the palmar border of the
_os pyramidale_, by a second slip to the outer border of the _os
capitato-hamatum_. This latter slip is usually connected in its
dorsal portion with the _extensor digitorum communis brevis_.
[Illustration: Fig. 76.
Muscles of forearm of _Rana esculenta_, dorsal view.
_aa_ M. anconaei.
_ec_ M. extens. digit. communis.
_Fd_ M. flex. digit.
]
*65, 66.* _M. anconaei s. extensores antibrachii_ (Fig. 76 _aa_).
*Dugès*, epicondylo-cubital and epitrochlo-cubital, n. 80, 81.
Both these muscles lie on the extensor side of the forearm; they
spring, the one from the _epicondylus lateralis_, the other from the
_epicondylus medialis_; converging, they run downwards, enclose the
olecranon, and are inserted into the upper (dorsal) border of the
ulna, each forming a penniform muscle. They are extensors of the
forearm and assist the _m. triceps_.
C. _MUSCLES OF THE HAND._
(I.) Muscles on the palmar surface.
(1) Muscles common to all the digits.
*67.* _M. flexor digitorum communis_ and _m. palmaris brevis_
(Fig. 77 _fd_, _pb_).
The origin and course of this muscle has been described above. At
its entrance into the palm it suddenly diminishes in size and passes
into a triangular aponeurosis, _aponeurosis palmaris_. Into the outer
border of this aponeurosis is inserted the _m. palmaris brevis_
(Fig. 77 _pb_); this latter muscle arises from the posterior or ulnar
border of the lower extremity of the radio-ulnar below the insertion
of the _mm. anconaei_, and runs obliquely downwards to this insertion.
From the lower free border of the aponeurosis a number of muscles
arise which will be described with the rest of the digital muscles.
(2) Muscles of the rudimentary thumb.
*68.* _M. abductor pollicis_ (Figs. 77, 78 _ap_).
*Dugès*, cubito-pollicien, n. 100.
This short muscle arises from the upper border of the lower extremity
of the radio-ulnar, passes transversely outwards, and is then
inserted into the anterior border of the rudimentary thumb.
*69.* _M. adductor pollicis_ (Figs. 77, 78 _ad.p_).
*Dugès*, sous-carpo-pollicien, n. 101.
This lies more superficially than the last, it arises from the palmar
surface of the _os capitato-hamatum_, and is inserted together
with the _abductor pollicis_ into the thumb. Several fibres of the
_extens. dig. II brevis_ are also inserted into the thumb. As this
member is completely covered with skin, the motions of which it is
capable are very limited.
(3) Muscles of the second finger, which serves the purposes of a
thumb.
*70.* _M. flexor digiti II longus s. sublimis_ (Fig. 77 _f2_).
*Dugès*, sous-carpo-phalangettien de l’index, n. 133.
[Illustration: Fig. 77.
Muscles of hand of _Rana esculenta_, volar surface, larger than
nature.
_A_ Aponeurosis palmaris.
_ab5_ M. abductor dig. V primus.
_ab5_′ M. abductor dig. secundus.
_ac_ MM. anconaei.
_adp_ M. adductor pollicis.
_ap_ M. abductor pollicis.
_ec_ M. extensor digitorum communis.
_e5_ M. extens. dig. commun. brevis.
_f2_ M. flexor dig. II longus.
_f3_ M. flexor dig. III longus.
_f4_ M. flexor dig. IV longus.
_f5_ M. flexor dig. V longus.
_fb2_ M. flexor dig. II brevis.
_fb3_ and _fb3_′ MM. flexores dig. III breves.
_fb4_ and _fb4_′ MM. flexores dig. IV breves.
_fb5_ M. flexor dig. V primus.
_fd_ M. flexor digitorum communis.
_o_ M. opponens.
_pb_ M. palmaris brevis.
I First finger, rudimentary thumb.
II Second finger, functions as thumb.
III-V Third to fifth fingers.
]
This is a flat muscle, which arises for the most part by fleshy
fibres from the hinder free border of the _aponeurosis palmaris_,
also by a smaller part from the palmar surface of the _os
capitato-hamatum_. It quickly passes into a thin long tendon which is
inserted into the terminal phalanx of the thumb (second finger).
[Illustration: Fig. 78.
Second layer of muscles on volar surface of hand of _Rana esculenta_,
larger than nature.
_ab5_ M. abductor dig. V primus.
_ab5_′ M. abductor dig. V secundus.
_ad2_ M. adductor dig. II.
_ad.p_ M. adductor pollicis.
_ap_ M. abductor pollicis.
_ec_ M. extensor carpi.
_fb2_ M. flexor dig. II brevis.
_fb2_′ M. flexor dig. II tertius.
_fp_ MM. flexores proprii phalangum.
_i3_ }
_i4_ } MM. interossei volares.
_i4_′}
_i5_ }
_o_ M. opponens dig. II.
_o_′ M. opponens dig. V.
_tt_ ′ MM. transversi metacarpi.
I-V as in Fig. 77.
]
*71.* _M. flexor digiti II brevis s. profundus_ (Fig. 77 _fb2_).
*Dugès*, sous-carpo-phalangien de l’index, n. 102.
This flat muscle, covered by the preceding, has a tendinous origin
from the palmar surface of the _os capitato-hamatum_, together with
one head of the _flexor sublimis_, and is inserted into the basal
phalanx.
*72.* _M. flexor digiti II tertius_ (Fig. 78 _fb2_′).
*Dugès*, tendini-phalangien de l’index, n. 103.
A small, thin muscle which arises close to the foregoing from the _os
capitato-hamatum_, and is inserted into the basal phalanx (see below,
_m. interosseus volaris I_).
*73.* _M. adductor digiti II_ (Fig. 78 _ad2_).
*Dugès*, métacarpo-métacarpien de l’index, n. 90.
This muscle represents the _adductor pollicis_ of man; it arises
from the base of the third os metacarpal and is inserted into the
metacarpal of the second finger, which latter it draws towards the
third finger.
*74.* _M. opponens digiti II_ (Figs. 77 and 78 _o_).
*Dugès*, sous-carpo-métacarpien de l’index, n. 90.
This muscle represents the muscle of like name in man. It arises from
the palmar process of the _os capitato-hamatum_ by a narrow tendon
and passes into a broad, flat muscle, which is inserted into the
under surface and outer border of the metacarpal of the second finger
throughout its length. It has, undoubtedly, the same action as the
corresponding muscle in man.
(4) Muscles of the third finger.
*75.* _M. flexor digiti III longus s. sublimis_ (Fig. 77 _f3_).
The smaller portion of this muscle arises from the free border of the
_aponeurosis palmaris_, the chief portion, together with the _flexor
brevis_, from the palmar surface of the _os capitato-hamatum_. The
two portions pass into one long tendon, which is inserted into the
last phalanx.
*76, 77.* _MM. flexores digiti III breves s. profundi I, II_
(Fig. 77 _fb3_ and _fb3_′).
*Dugès*, tendini-phalangiens du medius, n. 104, 105.
These two muscles arise in part from the free border of the
_aponeurosis palmaris_, in part from the volar surface of the _os
capitato-hamatum_, and pass backwards on either side of the muscle
last described, to be inserted into the basal phalanx. Dugès regards
these as analogues of the _mm. lumbricales_.
*78.* _M. flexor metacarpi dig. III._
This is a somewhat strong muscle, which arises by fleshy fibres from
the palmar surface of the _os capitato-hamatum_, and is inserted into
the palmar surface of the metacarpal bone.
(5) Muscles of the fourth finger.
*79.* _M. flexor digiti IV longus s. sublimis_ (Fig. 77 _f4_).
It arises at the free border of the _aponeurosis palmaris_, and is
inserted into the terminal phalanx by a thin tendon.
*80, 81.* _MM. flexores digiti IV breves s. profundi I, II_
(Fig. 77 _fb4_ and _fb4_′).
*Dugès*, tendini-phalangiens de l’annulaire, n. 108, 109.
Dugès regards these also as analogues of the _m. lumbricales_; they
arise on either side of the foregoing muscle from the free border
of the _aponeurosis palmaris_, and are inserted by tendons into the
basal phalanx.
*82.* _M. flexor proprius phalangum dig. IV_ (Fig. 78 _fp_).
*Dugès*, phalango-phalangien, n. 115.
A small muscle which arises by two slips from the palmar surface
of the basal phalanx, and is inserted into the base of the middle
phalanx.
*83.* _M. flexor metacarpi dig. IV_ (Fig. 78 _i4_).
This somewhat strong muscle arises from the _os capitato-hamatum_,
and is inserted into the palmar surface of the metacarpal bone.
(6) Muscles of the fifth finger.
*84.* _M. flexor dig. V longus s. sublimis_ (Fig. 77 _f5_).
This corresponds exactly with the corresponding muscle of the fourth
finger.
*85.* _M. flexor dig. V brevis_ (Fig. 77 _fb5_).
This muscle arises from the free border of the aponeurosis and is
inserted into the basal phalanx.
*86.* _M. flexor proprius phalangum dig. V_ (Fig. 78 _fp_).
*Dugès*, phalango-phalangien, n. 17.
It corresponds exactly with the corresponding muscle of the fourth
finger.
*87.* _M. opponens dig. V_ (Fig. 78 _o_′).
*Dugès*, deuxième sous-carpo-métacarpien du digitule, n. 92.
This muscle has a narrow origin from the palmar surface of the _os
capitato-hamatum_, it widens and is inserted into the outer border of
the metacarpal of the small finger. It draws this finger towards the
thumb.
*88.* _M. abductor dig. V primus_ (Figs. 77 and 78 _ab5_).
*Dugès*, sous-pyro-pré-métacarpien du digitule, n. 93.
This muscle arises from the palmar border and the outer surface of
the _os pyramidale_, and is inserted into the basal phalanx by a thin
tendon.
*89.* _M. abductor dig. V secundus_ (Figs. 77 and 78 _ab5_′).
*Dugès*, sous-pyro-post-métacarpien du digitule, n. 94.
It arises from the posterior part of the _os pyramidale_, is short,
and is inserted into the outer side of the metacarpal.
(II.) Muscles on the dorsal surface.
_M. extensor digitorum communis longus_ (Figs. 75 _ed_ and 77 _ec_).
*90.* _M. extensor digitorum communis brevis_ (Fig. 79 _e_3, _e_4,
_e_5).
*Dugès*, sous-pyro-phalangettien du III, IV, V, n. 124, 128, 131.
Covered by the foregoing, this muscle arises from the _os pyramidale_
in conjunction with the _extensor pollicis_ and from the _os
capitato-hamatum_. The part destined for the third finger, together
with that for the fourth, arises from the _os pyramidale_, passes
obliquely backwards into a tendon which runs along the inner side
of the corresponding finger to be inserted into the last phalanx.
That for the fifth finger arises from the inner projection of _os
capitato-hamatum_ being here attached to the insertion of the _m.
extensor carpi ulnaris_, and is inserted in a similar manner into the
terminal phalanx of the fifth finger.
*91.* _M. abductor digiti II_ (_i.e._ _pollicis_) _longus_
(Figs. 74 _ei_ and 79 _ab.2_).
For the origin and course of this muscle in the forearm see No. 63.
The muscle passes obliquely over the wrist-joint from the little
finger towards the inner side and from before backwards, it is
inserted into the metacarpal of the second finger (thumb). The place
of insertion of this muscle into the metacarpal (compare p. 47) is,
in the males, developed into a ridge and process, the muscle itself
is enlarged during the breeding season. This muscle abducts the thumb
and by this means presses upon the chest of the female when clinging
to her.
*92.* _M. extensor digiti II proprius longus_ (Fig. 79 _e2_, _e2_′).
*Dugès*, cubito-radio-sous-phalangien de l’index, n. 96.
[Illustration: Fig. 79.
Muscles of hand of _Rana esculenta_. Dorsal view, twice natural size.
_ab.2._ M. abductor dig. II longus.
_ab.2_′ M. abductor dig. II brevis.
_ad.2_ M. adductor dig. II.
_e2_ }
_e2_′ } M. extensor dig. II longus.
_e3_ }
_e4_ } M. extensor digitorum communis brevis.
_e5_ }
_eb2_ M. extensor dig. II proprius brevis.
_ec_ M. extensor carpi ulnaris.
_fa_ M. flexor antibr. lat. superficial.
_i_′3 }
_i_′4 } MM. interossei.
_i_′5 }
II-V as in Fig. 77.
]
This muscle lies obliquely on the back of the hand, parallel with
the _m. abductor digiti II_. It arises by two heads, one from the
tendon of the _flexor antibr. lat. superf._ (n. 60) upon the hinder
extremity of the radio-ulnar. This tendon conceals the hinder end
of this bone by means of a patella-like thickening, and sends forth
three tendinous prolongations; of these, the one is attached to the
ulnar border of the radio-ulnar, the second to the _os naviculare_,
while the third constitutes that portion of the _m. extens. dig. II
proprius long._ which is under consideration. The second head arises
from the _os pyramidale_ in connection with the _extensor digitorum
communis brevis_ (n. 90). The heads unite to form a long muscle,
which runs obliquely towards the second finger, passes into a tendon,
which, after forming connections by some muscular fibres with the
metacarpal, is inserted into the terminal phalanx.
*93.* _M. extensor dig. II proprius brevis_ (Fig. 79 _eb2_).
*Dugès*, sus-luno-phalangettien de l’index, n. 120.
This muscle lies between the preceding muscle and the _abductor dig.
II longus_. It arises from the _os naviculare_, and also includes
some fibres which arise from the second metacarpal. The tendon runs
along the radial side and is inserted along with the last muscle into
the terminal phalanx.
*94.* _M. abductor dig. II brevis_ (Fig. 79 _ab._2′).
*Dugès*, sus-luno-métacarpien de l’index, n. 88.
This represents the _abduct. pollic. brevis_ of man, lies on the
outer side of the hand, arises from the _os naviculare_, and is
inserted into the second metacarpal.
*95.* _M. extensor dig. III proprius._
*Dugès*, sus-luno-phalangettien du médius, n. 122.
This muscle has two heads of origin, from the _os naviculare_ and
_lunatum_. These form one muscular belly, which rapidly diminishes
and passes into a tendon; this, after receiving a few muscular fibres
from the second metacarpal, runs to the outer part of the dorsal
surface of this finger as far as the terminal phalanx, where it is
inserted.
*96.* _M. extensor dig. IV proprius._
*Dugès*, sus-pyro-phalangettien de l’annulaire, n. 128.
By a somewhat broad base, this muscle arises from the _os naviculare_
and _lunatum_. The tendon receives fibres from the fourth metacarpal
and runs on the outer half of the dorsal surface of this finger as
far as the middle phalanx, where it is inserted.
(III.) _MM. interossei._
*97, 98.* [*a.*] _MM. transversi metacarpi_ (Ecker), (Fig. 78 _t_,
_t_′, _ad2_).
These lie transversely between the metacarpals. There are three; the
first has been already described as _m. adductor digiti II_ (n. 73);
the second is stretched between the third and fourth metacarpals, and
the third between those of the fourth and fifth fingers.
*99, 100, 101.* [*b.*] _MM. interossei volares._
One may regard as such, four long, thin muscles, which take origin
near one another on the palmar surface of the carpal bones, and
diverge from this towards the second and fifth fingers.
1. The first of these muscles (Fig. 78 _fb2_′) has already been
described above as the _m. flexor digiti II tertius_ (n. 72).
2. The second (Fig. 78 _i3_) passes from the origin already described
to the palmar surface of the basal phalanx of the third finger.
3. The third (Fig. 78 _i4_) runs, in like manner, to the fourth
finger.
4. The fifth (Fig. 78 _i5_) to the fifth finger[46].
[Footnote 46: Whether these muscles may be regarded as _mm.
interossei_ is open to discussion, as they appear to act more as _mm.
opponentes_.]
*102* to *108*. _MM. interossei dorsales._
These arise in common from the metacarpals, and are inserted into the
basal phalanx of the corresponding surface on the finger.
1. The _third_ finger has two, one to the radial side (Fig. 79
_i_′3), one to the ulnar side.
2. The _fourth_ finger has three, the third (Fig. 79 _i_′4) arises
from the carpus, and perhaps ought rather to be regarded as an
extensor.
3. The _fifth_ finger has two.
IV. MUSCLES OF THE HINDER LIMB.
I. MUSCLES OF THE THIGH.
General arrangement (Figs. 80, 81).
*a.* The _m. triceps femoris_ forms the _outer border_ of the thigh,
and extends on to both the dorsal and ventral surfaces. The outer
border therefore corresponds with the anterior surface of the thigh
of man, in consequence of the thigh in the frog being normally
rotated outwards.
*b.* The _m. vastus internus_ (_v.i._) and a portion of the _adductor
longus_ (_ad_′), the _sartorius_ (_s_), a portion of the _adductor
magnus_ (_ad_‴), and the _rectus internus major_ (_r.i_′) are found
on the _inner surface_ of the thigh.
*c.* The _rectus internus minor_ (_r.i_″) forms the _inner border_.
*d.* On the _dorsal surface_ are to be seen, nearest the trunk,
the _glutaeus_ (_gl_), on the outer border the _vastus externus_
(_v.e._), the _pyriformis_ and _biceps_ (_p_ and _b_), then the
_semimembranosus_ (_sm_), and lastly the _rectus internus minor_
(_ri_″).
*e.* By reflecting the _rectus internus major_ (compare Fig. 82)
there are exposed to view: the _semitendinosus_ (_st_), the whole
length of the _adductor longus_, _magnus_ (_ad_′ and _ad_‴), and
_brevis_ (_ad_″). By reflecting the triceps, one sees (Figs. 84,
85) the _ilio psoas_ (_ip_), and beneath the _semimembranosus_, the
_quadratus_ (_qf_), and _capsularis femoris_ (_og_).
_Description of the separate Muscles._
(A.) Muscles of the dorsal surface.
*109.* _M. glutaeus_ (Fig. 80 _gl_).
*Dugès*, ex-ilio-trochantérien.--*Zenker*, _glutaeus maior_.
The tendinous origin of this muscle is found on the outer surface
and upper border of the two hinder thirds of the iliac bone. Thence
it runs outwards and backwards between the head of the _m. vastus
externus_ (_ve_) on the one side, and the _ilio-psoas_ and _rectus
anticus_ (_ra_) on the other, to be inserted into a tubercle
(trochanter) of the femur.
*110.* _M. Pyriformis_ (Fig. 80 _p_).
*Cuvier*, pyramidal.--*Dugès*, coccy-fémoral, n. 136.
A narrow, slender muscle, arising from the apex of the coccyx; it
passes obliquely outwards and backwards to the thigh, to be inserted
deeply between the _m. vastus externus_ and the _biceps_, into the
inner surface of the femur, but towards the ventral surface.
_M. triceps femoris s. extensor cruris communis_ (Fig. 80).
*Dugès*, pelvi-fémoro-rotulien, n. 145, 146, 147.
This is a large, strong muscle, having three heads of origin, and
inserted by a tendon into the tibio fibula. The three heads are the
_caput longum_ or the _rectus femoris anticus_ (_r.a._), the _caput
externum_ or the _vastus externus_ (_v.e._), and the _caput internum_
or the _vastus internus_ (Fig. 82 _vi_); of these, the first is
situated on the outer border of the thigh, the second on the dorsal
surface, and the third on the ventral surface.
[Illustration: Fig. 80.
Muscles of left thigh of _Rana esculenta_. Dorsal view.
_b_ M. biceps.
_ci_ M. coccygeo-iliacus.
_g_ M. gastrocnemius.
_gl_ M. glutaeus.
_p_ M. pyriformis.
_pe_ M. peroneus.
_r.a._ M. rectus anterior.
_ri_″ M. rectus internus minor.
_sm_ M. semimembranosus.
_t.a._ M. tibialis anticus.
_tr._ M. triceps fem.
_v.e._ M. vastus externus.
]
*111.* [*a.*] _M. rectus femoris anticus_ (Figs. 80, 82 _ra_).
This arises from the under (ventral) surface of the iliac bone about
its middle and beneath the _m. glutaeus_. The muscular belly quickly
passes into an aponeurosis, which covers the other two muscular
masses and combines with their tendons.
*112.* [*b.*] _M. vastus externus_ (Fig. 80 _v.e._).
It arises from the upper and hinder extremity of the iliac bone
(Fig. 42 _il_′) behind the _glutaeus_, which here sinks in between
this muscle and the _rectus anterior_.
*113.* [*c.*] _M. vastus internus_ (Figs. 81, 82 _vi_).
It arises from the whole of the under and outer surfaces of the
hip-joint capsule, and from tendinous slips which pass from this
capsule downwards on the under surface of the muscle, (from the
pubis and the femur I have not seen any fibres of origin, as stated
by others). Anteriorly the _vastus_ may easily be separated into
two heads. The two _vasti_ unite and form one muscular belly, in
the formation of which, as above stated, the _rectus anticus_ takes
no part. This united muscle passes into a tendon which, without the
mediation of a patella, passes over the knee-joint to be inserted
into the anterior extremity of the tibio fibula, and is prolonged
into the fascia of the leg.
*114.* _M. ilio-fibularis s. biceps_ (Fig. 80 _b_).
*Dugès*, ilio-péronien, n, 149.--*Zenker*, flexor externus tibiae,
p. 42.
This is a long, somewhat narrow muscle, which lies to the inner side
of, and partly covered by, the _vastus externus_, between which and
the semimembranous it is placed. It arises by a tendon between the
_ilio-psoas_ and _pyriformis_ from the ilium above the acetabulum
and behind the origin of the _vastus externus_. From here it passes
backwards, separated from the _vastus externus_ by a strong _ligam.
intermusculare_. On the inner side of this muscle, between it and
the _m. semimembranosus_, run the vessels of the thigh and the _N.
ischiadicus_. The muscle then divides into two portions, of which
one is inserted high up on the inner and under surface of the femur.
This is probably the muscle which Klein (_l. c._, p. 61) describes as
the _extensor brevis_. The other long muscular belly passes into a
thin tendon, opposite the hinder extremity of the thigh, it divides
into two portions; the anterior is inserted into the dorsal surface
of the hinder extremity of the femur, the other into the dorsal
surface of the tibio-fibula. Between the two is stretched an arch
with the concavity outwards. This insertion of the biceps is covered
by the stronger tendon of origin of the _m. gastrocnemius_ (compare
Fig. 87).
*115.* _M. semimembranosus_ (Figs. 80, 86 _sm_).
*Dugès*, sus-ischio-poplité, n. 148.--*Klein*, p. 60, _extensor
femoris sublimis_.
This muscle lies on the dorsal surface of the thigh, to the inner
side of the _biceps_ and _pyriformis_: it is a broad muscle, which
takes a tendinous origin from the hinder and upper angle of the
_symphysis ossis ilei_, and is inserted by a flat tendon into the
dorsal surface of the ligaments of the knee-joint, and through these
into the tibio-fibula. The tendon is formed rather abruptly from
the muscle, and is surrounded (Fig. 86) by the concave arch, which
forms the tendon of origin of the _gastrocnemius_ (_q. v._). A little
behind its middle (compare Fig. 81) the muscle is divided obliquely
into an anterior and a posterior portion by an aponeurotic septum. As
all the fibres are interrupted by this structure, the muscle may very
easily be torn through.
(B.) Muscles on the ventral surface.
*116.* _M. sartorius_ (Figs. 81, 82 _s_).
*Dugès*, sous-iléo-tibial, n. 150.--*Klein*, _gracilis_.
This long, flat muscle lies along the middle of the ventral surface
of the thigh; it arises by a tendon from the anterior inferior angle
formed by the symphysis of the innominate bones, and terminates in a
tendon behind the knee-joint, forming a kind of _pes anserinus_ in
the fascia of the leg, similar to that of the _semitendinosus_[47].
[Footnote 47: The sartorius has lately been used by Kühne in his
researches on the nerve-endings in muscle and on muscle contraction
without nerve supply (du Bois-Reymond’s and Reichert’s Archiv, 1859.
Page 314).]
*117.* _M. rectus internus major_ (Ecker), (Figs. 81 _r.i_′, 82
_ri_′).
*Dugès*, post-ischio-tibial profond, n. 152.--*Klein*,
_semimembranosus_.
This is a broad and flat muscle, thinned out at either extremity;
it occupies the inner half of the ventral surface of the thigh,
and is in relation with the _adductor magnus_ externally and
anteriorly, with the _sartorius_ posteriorly, and the _rectus minor_
muscle internally. The muscle arises by a tendon from the pubic
symphysis; it covers in its course the _semitendinosus_, then passes
into a strong tendon, which blends with the tendon of the _rectus
minor_, to be inserted by a slip into a process of the tibio-fibula
representing the _tuberositas tibiae_; first passing between the
tendons of the _sartorius_ and _semimembranosus_, which here form
an aponeurotic arch; a second slip passes under the tendon of the
_m. semitendinosus_ to be inserted into the upper surface of the
tibio-fibula, under it passes the _N. tibialis_. A third thread-like
tendon passes to the _m. semimembranosus_. Somewhat behind its middle
(Fig. 82) the muscle is traversed by an _inscriptio tendinea_, by
which the whole of the fibres are interrupted.
[Illustration: Fig. 81.
Muscles of left thigh of _Rana esculenta_. Ventral surface.
_ad_′ M. adductor longus.
_ad_″ M. adductor brevis.
_ad_‴ M. adductor magnus.
_e.c._ M. extensor cruris.
_f.t._ M. flexor tarsi.
_g.c._ M. gastrocnemius.
_r.i_′ M. rectus internus major.
_r.i_″ M. rectus internus minor.
_s_ M. sartorius.
_t.a._ M. tibialis anticus.
_t.p._ M. tibialis posticus.
_v.i._ M. vastus internus.
]
*118.* _M. rectus internus minor_ (Ecker), (Figs. 80, 81 _r.i_″).
*Dugès*, post-ischio-tibial superficiel, n. 151.--*Zenker*, _flexor
tibiae magnus_.--*Klein*, _ischio-tibialis_.
Situated entirely on the inner surface of the thigh, this narrow
muscle arises by a tendinous band which runs the whole length of the
pubic symphysis, and is connected posteriorly with the _sphincter
ani_, anteriorly with the _rectus abdominis_; posteriorly it passes
into a thin tendon which is also connected with the muscle just
described (117). In its course this muscle is attached to the skin
by strands of vessels and connective tissue.
The vastus internus major and minor together undoubtedly correspond
with rectus internus or gracilis of human anatomy. The rectus
internus major is, however, regarded as corresponding with the
adductor magnus by Dugès, and with the semimembranosus by Klein; by
considering the position and attachments of these muscles one must
arrive at a different conclusion.
_MM. adductores femoris._
*119.* [*a*] _M. adductor longus_ (Fig. 82 _ad_′).
*Dugès*, sous-ilio-fémoral, n. 141.
Without further dissection this muscle is only partially visible
between the _m. sartorius_ and _vastus internus_ (Fig. 81 _ad_′). The
muscle is flat and long, and arises by a tendon from the anterior
inferior angle of the pubic symphysis (Fig. 42 _s_), partially
covered by the origin of the _sartorius_. Thence the muscle passes
between the _vastus internus_ and the _adductor magnus_, and finally
is inserted below the middle of the femur, together with the latter
muscle.
[Illustration: Fig. 82.
Muscles of the left thigh of _Rana esculenta_. Ventral surface.
_ad_′ M. adductor longus.
_ad_‴ M. adductor magnus.
_gl_ M. glutaeus.
_ip_ M. ilio-psoas.
_ra_ M. rectus fem. anticus.
_ri_′ M rectus int. major.
_s_ M. sartorius.
_st_ M. semitendinosus.
_vi_ M. vastus internus.
]
*120.* [*b*] _M. adductor magnus_ (Figs. 81, 82 _ad_‴).
*Dugès*, sous-ischio-pubi-fémoral (adductor 1 and 2), n. 142,
143.--*Klein*, _adductor magnus_ and _extensor femoris profundus_.
This muscle is visible between the _sartorius_ and _rectus internus
major_ in the anterior half of the thigh, posteriorly it is covered
by these muscles. It arises by a tendon from (_a_) the pubic
symphysis and _ischii_, and is in this position divided into two
portions, between which passes the tendon of one head of the _m.
semitendinosus_ (Fig. 83 _st_″); (_b_) a second part arises from
this same tendon (Fig. 83 _st_‴) and joins with the first part. Thus
formed the muscle passes to be inserted into the distal half of the
inner surface of the femur as far as the condyle. Near its hinder
extremity, however, it passes on to the dorsal and outer surfaces,
and thus forms a kind of muscular sheath surrounding the distal
portion of the bone.
*121.* [*c*] _M. adductor brevis_ (Figs. 81, 83 _ad_″),
and
*122.* [*d*] _M. pectineus_ (Fig. 83 _pe_).
*Dugès*, sous-pubio-fémoral (analogue of the _pectineus_, possibly of
the _add. brevis_ also).
These two small muscles which lie under cover of the _sartorius_,
_adductor longus_ and _magnus_, appear externally as one muscle, but
may easily be separated (Fig. 83). They arise close together from
the pubic symphysis, and are inserted into the inner surface of the
anterior half of the femur. They are not attached to the _adductor
magnus_.
[Illustration: Fig. 83.
Deep muscles of left thigh of _Rana esculenta_.
_ad_′ M. adductor longus.
_ad_″ M. adductor brevis.
_ad_‴ M. adductor magnus.
_ip_ M. ilio-psoas.
_pe_ M. pectineus.
_ra_ M. rectus anticus,
_ri_′ M. rectus internus major }
_ri_″ M. rectus internus minor } cut through.
_s_ M. sartorius.
_st_ Belly of m. semitendinosus.
_st_′ M. semitendinosus (cap. posticum).
_st_″ M. semitendinosus (cap. anticum).
_st_‴ Fibres passing into the adductor magnus.
_vi_ M. vastus internus.
]
*123.* _M. semitendinosus_ (Fig. 83 _st_, _st_′, _st_″).
*Dugès*, bis-ischio-tibial, n. 153.--*Zenker*, _biceps_.
This is a long thin muscle, only visible after removal of the _m.
rectus internus_, by which it is entirely covered. It arises by two
long thin tendons, one (_caput posticum_, _st_′) from the pubic
symphysis, the other (_caput anticum_, _st_″) from the hollow between
the symphysis and the acetabulum. The latter passes through a slit
in the _adductor magnus_, and so affords this muscle another point of
origin; then backwards between the _adductor magnus_ and the _rectus
internus major_ and under the lower third of the thigh, and unites
with the posterior head of origin. The muscle so formed passes into
a thin tendon, and, together with that of the _sartorius_, forms an
aponeurotic arch, connected with the fascia of the leg, under which
the tendons of the _rectus internus major_ and _minor_ pass.
(C.) Deep muscles of the thigh.
To these, in addition to the _adductor brevis_, _pectineus_, and the
portion of the _biceps_ already described, belong also the following:
[Illustration: Fig. 84.
Deep muscles of the left thigh of _Rana esculenta_. Dorsal view.
_ad_′ M. adductor brevis.
_ci_ M. coccygeo-iliacus.
_cx_ Coccyx.
_gl_ M. glutaeus.
_il_ Ileum.
_ip_ M. ilio-psoas.
_o.g._ M. obturatorius.
_qf_ M. quadratus femoris.
]
[Illustration: Fig. 85.
Left half of pelvis of _Rana esculenta_. Thigh turned forwards under
the abdomen.
_gl_ M. glutaeus.
_og_ M. obturatorius.
]
*124.* _M. ilio-psoas_ (Figs. 82, 83, 84 _ip_).
*Dugès*, intra-ilio-fémoral (*_iliacus_ and _psoas_).--*Cuvier*,
*Zenker*, *Klein*, _iliacus internus_.
The fibres of this muscle take a broad origin from the pelvic surface
of the ilium, pass outwards over the lower margin of the bone and
form a flat muscle with its apex pointed posteriorly. It crosses the
hip-joint between the _m. rectus_ and _vastus internus_, covering
the hinder part of the _m. glutaeus_, and is inserted into the outer
surface of the middle third of the femur.
*125.* _M. quadratus femoris_ (Fig. 84 _qf_).
*Dugès*, post-ilio-fémoral (Homologue of the _glutaeus maximus_), n.
197.--*Zenker*, _glutaeus minor_, p. 42.
This muscle is of a somewhat elongated, triangular shape, and
arises, under cover of the _pyriformis_, from the ilium behind the
acetabulum; it passes backwards over the joint to be inserted into
the inner and under surfaces of the femur, between the _pyriformis_
and _ilio-psoas_; below, it is in direct relation with the _adductor
brevis_.
*126.* _M. obturatorius_ (Figs. 84, 85 _og_).
*Dugès*, ischio-pubi-fémoral, n. 139 (?).--*Zenker*, _m. capsularis
femoris_.
This small muscle is deeply situated upon the hip-joint, and covered
by all the other muscles that arise from the symphysis. Its origin
from the innominate bone extends from the superior posterior angle of
the _symph. ossis ilii_ to about the middle of the pubic symphysis;
the muscle fills the space between the crest of the symphysis and the
acetabulum. The fibres converge to pass into a strong tendon, which
is inserted into the posterior and anterior surfaces of the head of
the femur. The muscle appears to represent collectively the small
rotators of human anatomy, _m. obturator externus_ and _internus_ and
the _gemelli_.
II. MUSCLES OF THE LEG.
_General description._
On the outer surface (the anterior of man), covered by the _fascia
cruris_, into which the tendon of the _extensor communis cruris_ or
_triceps_ is prolonged, are found the following muscles: nearest to
the bone, the _m. extensor cruris brevis_ (_ec_); externally, the
_m. tibialis anticus_ (_ta_) and the _m. peroneus_ (_pe_). On the
inner surface (the hinder of man) lie the _gastrocnemius_ (_gc_) and
_tibialis posticus_ (_tp_), and deeply the _flexor tarsi sup._ (_ft_).
*127.* _M. gastrocnemius_ (Figs. 80, 81, 86).
*Dugès*, bi-fémoro-plantaire, n. 159.
This important muscle arises by two tendinous heads. The one (Fig. 86
_g_′) rather nearer the middle line of the popliteal space, is
by far the stronger: it arises by a broad, tendinous expansion,
which covers the knee-joint, and is attached to the femur and the
tibio-fibula by anterior and posterior bands respectively; it ends
internally in a concave aponeurotic arch: the second head is a thin,
tendinous slip, arising from the common tendon of the _triceps_ as
this lies on the knee-joint. The muscle is thickest near its origin,
and then gradually diminishes in size as it passes backwards; the
superficial surface is convex, the deep surface is flat. By tracing
the tendons of origin, they are seen soon to unite and form a common
flat tendinous surface, broad in front, contracted behind; this
aponeurosis lies in a plane running obliquely from the deep surface
towards the superficial surface, without, however, reaching this.
The muscular fibres arise from both surfaces of the aponeurosis, the
fibres of the two sides diverging slightly as they pass backwards
so as to be inclined at a small angle to each other. The fibres
are inserted into a fibrous expansion (_Ap_) which lies on the
superficial surface of the muscle; thin and slight in front, this
aponeurosis rapidly thickens posteriorly until it passes into the
_tendo Achillis_.
[Illustration: Fig. 86.
Muscles of the right leg and foot of _Rana esculenta_. Dorsal view.
_a.h._ M. abductor hallucis.
_a.l1_ M. abductor longus digiti I.
_A.p._ Aponeurosis plantaris.
_b_ M. biceps.
_e.t._ M. extensor tarsi.
_F.l._ M. flexor digitorum III, IV, V longus.
_F.l_′. M. flexor digitorum I and II longus.
_g_ M. gastrocnemius, drawn towards the right.
_g_′ Tendon of origin of gastrocnemius.
_l.c._ Ligamentum calcanei.
_p_ M. plantaris.
_r.i._ MM. internus maior and minor.
_s.m._ M. semimembranosus.
_s.t._ M. semitendinosus.
_t.A._ Tendo Achillis.
_t.A_′. Thickening of tendo Achillis.
_t.p._ M. tibialis posticus.
_v.e._ M. vastus externus.
_v.i._ M. vastus internus.
]
*128.* _M. tibialis posticus_ (Fig. 86 _t.p._).
*Dugès*, cruro-astragalien, n. 160.
Covered by the _gastrocnemius_ this muscle occupies the whole of the
inner and upper surfaces of the tibio-fibula, from which it arises
by numerous fibres. Opposite the hinder extremity of the bone the
muscle becomes free and passes somewhat abruptly into a tendon, which
courses behind and over the _malleolus internus_, on to the dorsum
of the foot, and is here inserted into the anterior extremity of the
_astragalus_. I cannot agree with Dugès that this muscle corresponds
with the _soleus_ (Ecker).
*129.* _M. extensor cruris brevis_ (Fig. 87 _ec_).
*Dugès*, pré-fémoro-tibial, n. 154.
Covered by the strong _fascia cruris_, and lying between the _m.
tibialis anticus_ and the tibio-fibula, this muscle arises by a long
tendon from the inner condyle of the femur; it passes backwards in
the groove on the anterior extremity of the tibio-fibula, covered by
the tendon of the triceps femoris, and is then inserted by muscular
fibres into the outer surface of the tibio-fibula almost as far as
the posterior third of the bone. (Dugès regards this muscle as the
upper, i. e. anterior, portion of the _tibialis anticus_.)
*130.* _M. tibialis anticus_ (Figs. 80, 81, 87 _ta_).
*Dugès*, pré-fémoro-astragalien and pré-fémoro-calcanien, n. 156 and
157; the former he regards as one part of the _tib. anticus_, the
latter as the _peroneus longus I_.--*Zenker*, _tib. ant. biceps_.
The tendon of origin of this muscle is attached to the femur
near the tendon of the _m. extensor cruris brevis_, and to the
joint-ligaments. The muscle is placed under the _fascia cruris_, its
long tendon of origin passing beneath the tendon of the _triceps_
in a special sheath through the joint; the tendon then gains a
muscular belly which bifurcates at about the middle of the leg,
forming two muscular masses, coursing along the outer and the inner
side of the leg respectively. The latter is inserted into the dorsal
surface of the _astragalus_ by a tendon, and the former into the
dorsal surface of the _calcaneus_ in a similar manner. The muscle
extends the foot and flexes the tarsus; the latter movement is very
distinct on account of the insertion of the muscle being so near the
_hypomochlion_.
*131.* _M. flexor tarsi anterior_ (Ecker), (Fig. 87 _Ft_).
*Dugès*, ex-tibio-astragalien, n. 155.--*Zenker*, _tibialis anticus
simplex_.
This muscle arises where the insertion of the _extensor cruris
brevis_ ceases, from the middle of the under surface of the
tibio-fibula, and passes backwards between the two tendons of the _m.
tibialis anticus_ along the outer side of this muscle, to be inserted
by a tendon into the inner side of the anterior articular extremity
of the _astragalus_ and the _fascia dorsalis pedis_.
[Illustration: Fig. 87.
Muscles of leg and foot of _Rana esculenta_, seen from below.
_a.b.5_ M. abductor dig. V longus.
_ec_ M. extensor cruris brevis.
_e.d.1_ M. extensor digit I longus.
_e.d.4_ M. extensor digit IV longus.
_e.d.5_ M. extensor digit V longus.
_Ft_ M. flexor tarsi anterior.
_Ft_′ M. flexor tarsi posterior.
_g_ M. gastrocnemius.
_p_ M. peroneus.
_ta_ M. tibialis anticus.
_tF_ M. triceps femoris.
]
*132.* _M. peroneus_ (Figs. 80 _pe_, 87 _p_).
*Dugès*, génio-péronéo-calcanien, n. 158.
This is a strong muscle which is attached by a long tendon of
origin to the hinder extremity of the femur and the ligaments of
the knee-joint. The tendon runs in a sheath through the joint and
posteriorly becomes muscular; the muscle passes downwards on the
outer side of the tibio-fibula to be inserted into the _malleolus
externus_ of this bone and into the anterior extremity of the
_calcaneus_. It has an action similar to that of the _m. tibialis
anticus_.
III. MUSCLES OF THE FOOT.
A. _MUSCLES ON THE PLANTAR SURFACE._
*133.* _Aponeurosis plantaris_ (Fig. 88 _A.p._).
As already mentioned, the tendon of the _m. gastrocnemius_ is, at
the heel, continued into a strong aponeurosis, and possesses at this
place a thickening[48]. The aponeurosis is of triangular form, the
base directed towards the toes and attached to these. The lateral
borders of this triangle are continued into weaker _fasciae_, which
are attached to the two long tarsal bones. The inner border in
particular gives a strong bundle of fibres to the astragalus, and is
thus connected with the fascia of the dorsum of the foot; externally
this aponeurosis is attached to a cartilage (Dugès, os sesamoïde, _l.
c._, n. 66), situated on the plantar surface of the joint between the
_calcaneus_ and the _os metatarsi IV_.
[Footnote 48: Lehmann, Ueber den Knorpel in der Achillessehene des
Frosches, Zeitschs. f. U. Zool. XIV, p. 109. (See also literature on
cartilage, Sect. VII.)]
*134.* _Ligamentum calcanei_ (Ecker), (Figs. 88, 89 _l.c._).
If the _tendo Achillis_ be divided and the _aponeurosis plantaris_
reflected towards the toes, there is seen, arising from the posterior
head of the tibio-fibula, in its whole breadth, a ligament (between
the _tib. posticus_ and _peroneus_). This ligament forms a firm
surface on which the thickened portion of the _tendo Achillis_ may
move, and which evidently represents the tuberosity of the heel bone.
I have therefore named the entire structure the _ligamentum calcanei_.
[Illustration: Fig. 88.
Muscles of the right leg and foot of _Rana esculenta_. Dorsal view.
_a.h._ M. abductor hallucis.
_a.l_I M. abductor longus digiti I.
_A.p._ Aponeurosis plantaris.
_b_ M. biceps.
_e.t._ M. extensor tarsi.
_F.l._ M. flexor digitorum III, IV, V longus.
_F.l._′ M. flexor digitorum I and II longus.
_g_ M. gastrocnemius, drawn towards the right.
_g_′ Tendon of origin of gastrocnemius.
_l.c._ Ligamentum calcanei.
_p_ M. plantaris.
_r.i._ MM. internus maior and minor.
_s.m._ M. semimembranosus.
_s.t._ M. semitendinosus.
_t.A._ Tendo Achillis.
_t.A_′. Thickening of tendo Achillis.
_t.p._ M. tibialis posticus.
_v.e._ M. vastus externus.
_v.i._ M. vastus internus.
]
Several muscles arise from this ligament, viz.:--
*135.* _M. extensor tarsi_ (Klein), (Figs. 88, 89 _e.t._).
*Dugès*, tibio-sous-astragalien (regarded by him as the homologue of
the _tibialis posticus_).
Covered by the two succeeding muscles, this muscle arises from the
_ligamentum calcanei_, runs backwards, and is inserted into the whole
length of the plantar surface of the _astragalus_. It extends the
foot.
*136.* _M. plantaris_ (Figs. 88, 89 _p_).
This takes its origin from the _ligamentum calcanei_ to the inner
side and below the last muscle. It passes backwards and is inserted
into the dorsal surface of the _aponeurosis plantaris_.
[Illustration: Fig. 89.
Muscles of the plantar surface of foot of _Rana esculenta_, twice
natural size.
_A.p._ Aponeurosis plantaris, divided.
_ab.5._ M. abductor dig. V.
_ad.5._ M. adductor dig. V.
_ad.l.1._ M. adductor longus dig. I.
_e.t._ M. extensor tarsi.
_F.5._ M. flexor brevis dig. V.
_F.l._ M. flexor digitorum III, IV, V longus.
_F.l_′. M. flexor digitorum I, II longus.
_l.1._}
_l.2._}
_l3_ }
_l3_′ } Musculi lumbricales.
_l4_′ }
_14_″ }
_l.5._}
_l.c._ Ligamentum calcanei.
_p_ M. plantaris.
_t.A._ Tendo Achillis.
_t.A_′. Thickening in tendo Achillis.
_t.p._ M. transversus plantae posterior.
_t.p._′ M. transversus plantae anterior.
]
*137.* _M. flexor digitorum III_, _IV_, _V longus_ (Ecker),
(Figs. 88, 89 _F.l._).
*Dugès*, péronéo-sous-phalangettien (_flexor dig. longus_).
This muscle also arises from the _ligamentum calcanei_ to the outer
side of the _m. plantaris_. It runs backwards over the _aponeurosis
plantaris_, and at the free margin of this passes somewhat suddenly
into a strong tendon, which traverses an aponeurotic canal, formed by
fibres of the aponeurosis passing above and below the tendon, from
the cartilaginous enlargement in the tendon to the median border of
the aponeurosis. The tendon forms three slips for the fifth, fourth,
and third toes: these are slightly attached to the aponeurosis,
but reach beyond its free border to be inserted into the terminal
phalanges of the toes mentioned, and are held down by fibrous bands.
(The small _m. lumbricales_ arising from these tendons are described
below.)
*138.* _M. flexor digitorum I_, _II longus_ (Ecker), (Figs. 88, 89
_F.l_′.).
The tendons, by means of which the terminal phalanges of the first
and second toes are flexed, arise directly from the posterior border
of the aponeurosis.
*139, 140.* _MM. transversi plantae_ (Ecker), (Fig. 89 _t.p._,
_t.p_′.).
The movements of the aponeurosis and through it the movements of
the tendons attached to it are influenced not only by the _m.
gastrocnemius_ and _plantaris_, but also by two other muscles, which
together have been described as the _flexor dig. longus internus_
(Klein), or as the tarso-sous-phalangettien (Dugès, 221).
*a.* _M. transversus plantae posterior_ (_t.p._).
This takes its origin from the plantar cartilage, widens as it
courses backwards and inwards to be inserted into the dorsal surface
of the _aponeurosis plantaris_; from this the tendons for the first
and second toes (_flexor dig. longus I_ and _II_) arise, thus there
is no direct connection between the muscular fibres of the two
muscles.
*b.* _M. transversus plantae anterior_ (_t.p_′.).
This muscle is covered by the last; broader anteriorly, it arises
from the calcaneum, and is inserted to the inner side of the last
muscle into the dorsal surface of the aponeurosis. This muscle, like
that just described, is not continued directly into the tendon of the
flexor of the toes, they cannot therefore be regarded as flexors of
the toes.
*141* to *149*. _Musculi lumbricales_ (Fig. 89 _l.1–5_).
(A.) From the posterior border of the _aponeurosis plantaris_ arise:--
(1) _M. lumbricalis digiti I_ (_l.1_).
*Dugès*, tendini-sous-phalangien de pouce, n. 185.
This is inserted into the anterior extremity of the proximal phalanx.
(*2*) _M. lumbricalis digiti II_ (_l.2_).
*Dugès*, tendini-sous-phal. du I doigt, n. 186 (and 187), double
according to Dugès.
Similarly inserted.
(*3* and *4*) _MM. lumbricales digiti III_ (_l.3_).
*Dugès*, tendini-sous-phal. du III doigt, n. 188, single according to
Dugès.
One of these (_l3_) is inserted into the anterior extremity of the
basal phalanx, the other (_l3_′) into a corresponding position on the
middle phalanx.
(*5*) _M. lumbricalis digiti IV._
*Dugès*, tendini-sous-phal. du IV doigt.
Inserted into the anterior extremity of the basal phalanx.
(B.) Arising from the tendons of the _flexor longus III_, _IV_, _V_:
(*6* and *7*) _MM. lumbricales digiti IV_ (_l.4_′. and _l.4_″.).
*Dugès*, tendini-sous-phalanginien du IV doigt, n. 201, 202.
The first (_l.4_′) is inserted into the posterior end of the basal
phalanx, the second (_l.4_″) in a similar position into the second
phalanx.
(*8*) _M. lumbricalis digiti V_ (_l.5._).
*Dugès*, tendini-sous-phalangien du V doigt, n. 203.
This arises from the tendon for the fifth toe, runs backwards as a
thin tendon alongside that of the flexor, and is inserted into the
middle phalanx.
_Special Muscles of the Separate Toes._
(I.) Muscles of the rudimentary great toe.
*150.* _M. abductor hallucis_ (Figs. 88 _a.h._, 90).
*Dugès*, tibio-sous-tarsien, n. 163.
This muscle arises from the inner border of the _aponeurosis
plantaris_, at the spot where the _m. plantaris_ is inserted, it may
therefore almost be regarded as a continuation of this muscle; it is
inserted into the anterior border of the rudimentary toe.
(II.) Muscles of the great and first toes.
*151.* _M. adductor longus digiti I_ (Figs. 89, 90 _ad.l1_).
*Dugès*, calcanéo-scaphoidien, n. 164.
This powerful muscle arises from the plantar surface of the calcaneum
and astragalus; its fibres converge towards a tendon lying in its
middle, which becomes free towards its posterior end; the tendon
passing inwards under the _ligamentum tarsi transversum_ through
a groove on the hinder extremity of the astragalus in an arched
direction, to be inserted into the _os naviculare_, which bears the
rudimentary great toe and the _os metatarsi I_.
(III.) Muscles of the first toe.
*152.* _M. abductor longus digiti I_ (Figs. 88 _al.1_, 90 _a.b.1_).
It takes its origin from the inner border of the _aponeurosis
plantaris_, and lies on the plantar surface of the _abductor
hallucis_. Its tendon runs in the hollow which the great toe forms,
and is inserted into the inner side of the _os metatarsi I_.
*153.* _M. flexor brevis digiti I_ (Fig. 90 _F.b.1_).
A small, thin muscle, which arises from the anterior extremity of
the _os metatarsi II_, and is inserted into the basal phalanx of the
first toe. In this small muscle, and also in the _m. lumbrical. dig.
V_ (Fig. 89 _l.5._), the nerve distribution may be very well seen.
*154.* _M. opponens dig. I_ (Fig. 90 _op_).
*Dugès*, sous-metatarso-phalangien du pouce, n. 192.
This is situated to the inner side of the preceding muscle, arises
from the _os metatarsi II_ somewhat narrow, widens in a fan-like
manner towards the _os metatarsi I_, into the anterior half of which
it is inserted.
(IV.) Muscles of the second toe.
*155.* _M. flexor metatarsi dig. II_ (Fig. 90 _F.m.2_).
*Dugès*, sous-tarso-metatarsien du II doigt.--*Klein*, extensor
metatarsi.
By a narrow origin from the hinder end of the calcaneum, posteriorly
this muscle becomes broader and is inserted, somewhat thinned out,
into the plantar surface of the second _os metatarsi_.
*156.* _M. flexor dig. II proprius_ (Fig. 90 _F.p.2_).
*Dugès*, sous-metatarso-phalangien, n. 194.
It arises from the plantar surface of the _os metatarsi II_, and
is inserted by a thin tendon into the plantar surface of the first
phalanx.
Dugès describes this and the analogous muscles of the third, fourth,
and fifth toes (_F.p.3_, _4_, _5_) as the _interossei plantares_, a
nomenclature which, to me, does not appear correct, as these muscles
lie entirely on the plantar surface, and do not adduct or abduct the
toes, but flex them.
(V.) Muscles of the third toe.
*157.* _M. flex. metatarsi dig. III_ (Ecker), (Fig. 90 _F.m.3_).
*Dugès*, sous-calcaneo-métatarsien du III doigt, n. 174.--
*Klein*, _extensor metatarsi_.
Like the corresponding muscle of the second toe (n. 155), this
arises by a small tendon from the hinder extremity of the calcaneum,
runs backwards and is inserted into the plantar surface of the _os
metatarsi III_. The greatest portion of the muscle lies beneath
the _m. transversus metatarsi_ (_tm_), the most anterior portion,
however, lies above this. Dugès has described this latter portion as
a special muscle (n. 176, metatarso-métatarsien du III), the same
description holds good for the second toe (n. 177, Dugès).
*158.* _M. flexor dig. III proprius_ (Ecker), (Fig. 91 _Fp3_).
*Dugès*, sous-métatarso-phalangien du III doigt, n. 195.
Like the corresponding muscle of the second toe, this arises from
the plantar surface of the _os metatarsi III_, and is inserted by a
thin tendon into the plantar surface of the anterior extremity of the
first phalanx.
[Illustration: Fig. 90.
Muscles of plantar surface of foot of _Rana esculenta_.
_a.b.1_ M. abductor longus digiti I.
_ab5_ M. abductor digiti V.
_ad.l.1_ M. adductor longus digiti I.
_a.h._ M. abductor hallucis.
_F.b.1_ M. flexor brevis digiti I.
_F.m.2_, _3_, _4_ M. flexores metatarsi II, III, IV.
_F.p.2_, _3_, _4_, _5_ MM. flexor. proprii digit. 2, 3, 4, 5.
_F.ph.3_, _4_, _4_′, _5_ MM. flexor. phalang. digit. 3, 4, 5.
_op_ M. opponens digiti I.
_t.m_′ }
_t.m_″ } MM. transversi metatarsi 1, 2, 3.
_t.m_‴ }
]
*159.* _M. flexor phalangum proprius digiti III_ (Ecker), (Fig. 91
_F.ph.3_).
*Dugès*, phalango-phalangien, n. 204.
This arises by tendon from the plantar surface of the basal phalanx,
and is inserted into the anterior extremity of the terminal phalanx.
(VI.) Muscles of the fourth toe.
*160.* _M. flexor metatarsi dig. IV_ (Fig. 91 _F.m.4_).
*Dugès*, métatarso-métatarsien, n. 175.
Similarly to the corresponding muscle of the third toe, this one
arises from the hinder extremity of the calcaneum, and is inserted
into the anterior portion of the plantar surface of the _os metatarsi
IV_, but not into the greater portion of this surface, as in the
second and third _os metatarsi_.
*161.* _M. flexor dig. IV proprius_ (Fig. 91 _Fp4_).
*Dugès*, sous-métatarso-phalangien du IV doigt (_interosseus
plantaris_), n. 196.
The origin and insertion are similar to those of the muscles of the
second and third toes.
[Illustration: Fig. 91.
Muscles of plantar surface of foot of _Rana esculenta_.
_a.b.1_ M. abductor longus digiti I.
_ab5_ M. abductor digiti V.
_ad.l.1_ M. adductor longus digiti I.
_a.h._ M. abductor hallucis.
_F.b.1_ M. flexor brevis digiti I.
_F.m.2_, _3_, _4_ M. flexores metatarsi II, III, IV.
_F.p.2_, _3_, _4_, _5_ MM. flexor. proprii digit. 2, 3, 4, 5.
_F.ph.3_, _4_, _4_′, _5_ MM. flexor. phalang. digit. 3, 4, 5.
_op_ M. opponens digiti I.
_t.m_′ }
_t.m_″ } MM. transversi metatarsi 1, 2, 3.
_t.m_‴ }
]
*162.* _M. flexor brevis dig. IV._
A small muscle, which arises with the _m. flexor brevis_ of the fifth
toe, from enlargement of _aponeurosis plantaris_, and is inserted
into the basal phalanx of the fourth toe.
*163.* _M. flexor phalangum proprius dig. IV anterior_ (Fig. 91
_F.ph.4_).
*Dugès*, phalango-phalanginien, n. 205.
It resembles the corresponding muscle of the third toe.
*164.* _M. flexor phalangum proprius posterior_ (Fig. 91 _F.ph.4_′).
*Dugès*, phalangino-phalangettien, n. 209.
This extends from the plantar surface of the second phalanx to the
anterior extremity of the third.
(VII.) Muscles of the small toe.
*165.* _M. abductor dig. V_ (Fig. 91 _a.b.5_).
*Dugès*, calcanéo-ex-métatarsien du digitule, n. 169.
This muscle arises from the hinder extremity of the calcaneum, and is
inserted into the outer surface of the fifth metatarsal.
*166.* _M. adductor dig. V_ (Fig. 89 _a.d.5_).
*Dugès*, sous-tarso-in-phalangien, n. 191.
This arises from the cartilage of the plantar aponeurosis, and is
inserted into the hinder end of the fifth metatarsal.
*167.* _M. flexor brevis dig. V_ (Fig. 89 _F.5_).
*Dugès*, sous-tarso-ex-phalangien, n. 190.
Arising from the same place as the preceding, it extends to the basal
phalanx.
*168.* _M. flexor dig. V. proprius_ (Fig. 91 _F.p._5).
(Analogues of Muscles, n. 156, 158, 161; see note at n.
156).--*Dugès*, sous-métatarso-phalangien, n. 197 (*_inteross.
plant._).
This muscle arises from the plantar and inner surfaces of the fifth
metatarsal, and is inserted into the basal phalanx.
*169.* _M. flexor phalangum proprius_ (Fig. 91 _F.ph.5_).
*Dugès*, phalango-phalanginien, n. 206.
Its origin and insertion are as in the corresponding muscles of the
second, third, and fourth toes, n. 159, 163, 164, 169.
*170* to *172*. _MM. interossei_ (Fig. 91 _t.m._).
*Dugès*, 1, 2, and 3, intermétatarsien, n. 170, 171, 172.
These are three muscles with their fibres arranged transversely,
which occupy the anterior portion of the spaces between the
metatarsals, and approximate these. The first arises (_tm_′) from the
edge of the plantar surface of the first metatarsal, and is inserted
into the corresponding part of the second: the second (_tm_″) passes
from this point to the third, and the third (_tm_‴) to the fifth.
B. _MUSCLES OF THE DORSAL SURFACE._
*173.* _M. flexor tarsi posterior_ (Ecker), (Fig. 92 _F.t._).
*Dugès*, péronéo-sus-astragal, n. 161.
This is a strong muscle, which has a narrow origin from the outer
side of the tibio-fibula, directly over the distal extremity, and is
inserted into the dorsal surface of the astragalus from the middle to
the distal extremity.
Muscles of the first toe.
*174.* _M. extensor longus dig. I_ (Fig. 92 _e.l.1_).
*Dugès*, calcanéo-sus-métatarsien du pouce, n. 166.
This lies to the outer side of and near the foregoing muscle; it
arises by a long, strong head from the middle of the calcaneum, runs
obliquely backwards and inwards to unite with a small head which
arises from the common epiphysis of the astragalus and calcaneum, in
common with the _m. extensor dig. II_. The muscle so formed passes
into a flat tendon to be inserted into the basal phalanx of the first
toe.
*175.* _M. extensor brevis dig. I_ (Fig. 92 _e.b.1_).
A small, short muscle which arises from the _os naviculare_ and is
inserted into the dorsal surface of the first metatarsal.
*176.* _M. abductor brevis dig. I_ (Fig. 92 _a.b.1_).
*Dugès*, ex-tarso-métatarsien du pouce, n. 168.
This small muscle is situated near the preceding; it arises from the
first bone of the supplemental toe, and is inserted into the inner
side of the first metatarsal.
Muscles of the second toe.
*177.* _M. extensor dig. II longus_ (Fig. 92 _e.l.2_).
*Dugès*, calcanéo-sus-phalangien du II doigt, n. 182.
This arises from the calcaneum, in common with the _m. extensor
longus_ of the third toe, and is inserted into the basal phalanx of
the second toe by a tendon.
*178.* _M. extensor dig. II brevis_ (Fig. 92 _e.b.2_).
*Dugès*, astragalo-sus-phalangien du II, n. 183.
This is partly covered by the preceding muscle: it arises from the
astragalus, and unites with the tendon of the preceding muscle.
Muscles of the third toe.
*179.* _M. extensor dig. III longus_ (Fig. 92 _e.l.3_).
*Dugès*, sus-astragalo-phalangien du médius, n. 199.
This arises with the _extensor longus_ of the second toe from the
calcaneum: its tendon unites with that of the following muscle.
*180.* _M. extensor dig. III brevis_ (Fig. 92 _e.b.3_).
*Dugès*, astragalo-sus-phalangien du médius, n. 181.
This muscle arises from the astragalus, and is inserted with the
tendon of the preceding muscle into the dorsal surface of the basal
phalanx.
[Illustration: Fig. 92.
Dorsal view of muscles of foot of _Rana esculenta_.
_a.b.1_ M. abductor brevis dig. I.
_e.b.1_ M. extensor brevis dig. I.
_e.b.2_ M. extensor brevis dig. II.
_e.b.3_ M. extensor brevis dig. III.
_e.b.4_ M. extensor brevis 1 dig. IV.
_e.b.4_′ M. extensor brevis 2 dig. IV.
_e.b.5_ M. extensor brevis dig. V.
_e.l.1_ M. extensor longus dig. I.
_e.l.2_ M. extensor longus dig. II.
_e.l.3_ M. extensor longus dig. III.
_e.l.4_ M. extensor longus dig. IV.
_e.l.5_ M. extensor longus dig. V.
_F.t_ M. flexor tarsi posterior.
_i.2_ to _i.10_ MM. interossei.
]
Muscles of the fourth toe.
*181.* _M. extensor longus dig. IV_ (Fig. 93 _e.l.4_).
*Dugès*, péroneo-sus-phalangien du IV, n. 178.
A narrow muscle arising in common with the _flexor tarsi inf._, but
external to it. It is inserted into the tendinous expansion on the
dorsum of the toe.
*182.* _MM. extensores dig. IV breves_ (Fig. 93 _e.b.4_ and
_e.b.4_′).
*Dugès*, calcanéo-sus-phalangien and sus-calcanéo-phalanginien, n.
179 and 198.
These two small muscles arise from the calcaneum: one is inserted
into the basal phalanx, the other, by means of a long thin tendon,
passes along with the tendon of the corresponding _m. interosseus_ to
the second phalanx, to which it is attached.
Muscles of the fifth toe.
*183.* _M. extensor dig. V longus_ (Fig. 93 _e.l.5_).
*Dugès*, calcanéo-sus-métatarsien, n. 165.
A strong muscle which covers almost the whole length of the
calcaneum; it arises from the anterior extremity of this bone,
runs backwards to the outer side of the dorsum of the foot, and is
attached to the outer surface of the fifth metatarsal.
*184.* _M. extensor dig. V brevis_ (Fig. 93 _e.b.5_).
*Dugès*, calcanéo-sus-phalangien du V, n. 180.
This is a long thin muscle, which, together with the muscle last
described, arises from the calcaneum and is inserted into the basal
phalanx of the fifth toe.
*185.* _M. abductor dig. V brevis_ (Fig. 93 _i.10_).
This, the last _m. interosseus_, arises from the outer side of the
fifth metatarsal, and is inserted into the hinder extremity of the
second phalanx of the same toe.
*186* to *195*. _MM. interossei dorsales_ (Fig. 93 _i.1_ to _i.10_).
First toe.
(1) The analogue of the first _m. interosseus_ is the _m. abductor
brevis dig. I_ (_a.b.1_).
(2) The second _m. interosseus_ (_i.2_) arises from the outer side
of the first metatarsal, and is inserted into the outer surface of
the second phalanx of the same toe, dorsally to the _m. opponens_ and
_flexor brevis dig. I_.
Second toe.
(3) The third _m. interosseus_ (_i.3_) takes origin from the anterior
part of the outer surface of the first metatarsal by a thin tendon;
it is inserted into the inner surface of the second phalanx by a
similar tendon.
(4) The fourth _m. interosseus_ (_i.4_) arises from the outer side of
the second metatarsal, and is inserted into the outer surface of the
second phalanx.
Third toe.
(5) The fifth _m. interosseus_ arises from the outer surface of the
second metatarsal, and is inserted by a thin tendon into the inner
surface of the second phalanx of the same toe.
(6) The sixth arises from the outer surface of the third metatarsal,
and is inserted laterally by a thin tendon into the hinder extremity
of the second phalanx of the same toe.
[Illustration: Fig. 93.
Dorsal view of muscles of foot of _Rana esculenta_.
_a.b.1_ M. abductor brevis dig. I.
_e.b.1_ M. extensor brevis dig. I.
_e.b.2_ M. extensor brevis dig. II.
_e.b.3_ M. extensor brevis dig. III.
_e.b.4_ M. extensor brevis 1 dig. IV.
_e.b.4_′ M. extensor brevis 2 dig. IV.
_e.b.5_ M. extensor brevis dig. V.
_e.l.1_ M. extensor longus dig. I.
_e.l.2_ M. extensor longus dig. II.
_e.l.3_ M. extensor longus dig. III.
_e.l.4_ M. extensor longus dig. IV.
_e.l.5_ M. extensor longus dig. V.
_F.t_ M. flexor tarsi posterior.
_i.2_ to _i.10_ MM. interossei.
]
Fourth toe.
(7) The seventh _m. interosseus_ (_i.7_) arises by a thin tendon from
the hinder extremity of the astragalus, and by fleshy fibres from
the hinder extremity of the fourth metatarsal; it is inserted by a
thin tendon into the inner surface of the second phalanx of the same
toe.
[Illustration: Fig. 94.
Dorsal view of muscles of foot of _Rana esculenta_.
_a.b.1_ M. abductor brevis dig. I.
_e.b.1_ M. extensor brevis dig. I.
_e.b.2_ M. extensor brevis dig. II.
_e.b.3_ M. extensor brevis dig. III.
_e.b.4_ M. extensor brevis 1 dig. IV.
_e.b.4_′ M. extensor brevis 2 dig. IV.
_e.b.5_ M. extensor brevis dig. V.
_e.l.1_ M. extensor longus dig. I.
_e.l.2_ M. extensor longus dig. II.
_e.l.3_ M. extensor longus dig. III.
_e.l.4_ M. extensor longus dig. IV.
_e.l.5_ M. extensor longus dig. V.
_F.t_ M. flexor tarsi posterior.
_i.2_ to _i.10_ MM. interossei.
]
(8) The eighth _m. interosseus_ (_i.8_) takes its origin from the
outer surface of the fourth metatarsal and from the inner surface of
the fifth: it is inserted into the hinder extremity of the second
phalanx.
Fifth toe.
(9) The ninth _m. interosseus_ (_i.9_) arises from the inner surface
of the fifth metatarsal, and is inserted into the hinder extremity of
the second phalanx.
(10) The tenth _m. interosseus_ has already been described as the
_abductor digiti V brevis_ (Fig. 94 _i.10_).
If we take the fourth toe as the axis of movement, the first, third,
fifth, seventh, eighth, and tenth _mm. interossei_ will abduct from
an imaginary line which runs through this toe. The second, fourth,
sixth, and ninth will adduct towards this line. If we compare them
with those of man (in whose case the second toe affords the central
line), those of the first group must be regarded as _mm. interossei
dorsales_, of the latter as _plantares_. Dugès holds all these
_interossei_ (with the exception of the first, _abductor brevis dig.
I_) to be _mm. interossei dorsales_ (métatarso-sus-phalangettiens, n.
210, 211, 212, 214, 215, 216, 218, 219). Those which I have described
as _flexores proprii digitorum_, he regards as _interossei volares_.
V. MUSCLES OF THE SKIN.
*196.* _M. cutaneus pectoris_ (Fig. 95 _cp_).
*Dugès*, abdomino-guttural, n. 53.--*Klein*,
abdomino-cutaneus.--*Zenker*, subcutaneus pectoris.
This is an elongated quadrangular muscle, attached by its hinder
margin to the side of the xiphisternum, and to the superficial
surface of the aponeurosis of the _m. obliquus externus_. The fibres
course forwards and slightly outwards to be inserted, at a very acute
angle, into the skin: lying between the two muscles and attached
to them on either side is a thin fascia, which, together with the
muscles and the _septum thoracicum_, assists in closing a triangular
space between these structures and the deeper muscles.
The thinness and transparency of this muscle render it especially
suitable for the investigation of nerve-terminations[49].
[Footnote 49: Kölliker, Mikrosk. Anatomie, 1866, vol. II. 1,
p. 247; Reichert, Müller’s Archiv, 1851, p. 29, Pl. I; Kölliker,
Untersuchungen über die letzten Endigungen der Nerven in den Muskeln
des Frosches; Leipzig, Engelmann, 1862.]
[Illustration: Fig. 95.
Pectoral region of _Rana esculenta_.
_cp_ M. cutaneus pectoris.
_p_″ Port. abdominalis of the m. pectoralis.
]
*197.* _M. cutaneus dorsi_ (Fig. 96 _cd_).
*Dugès*, pubio-dorso-cutané, n. 56.--*Zenker*, _cutaneus iliacus_.
This muscle has a narrow origin in the space between the muscles of
the belly and of the thigh, and is here inserted into the fasciae,
which are attached to the pubic symphysis; it passes inwards and
upwards to the outer side of the anterior insertion of the _m. rectus
femoris anticus_, then widens and is inserted by diverging fibres
into the inner surface of the skin of the hinder portion of the back.
*198.* _M. coccygeo-cutaneus._
*Dugès*, coccy-dorso-cutanés, n. 57.
The muscular fibres which Dugès has described under this name, lie
covered by the _m. pyriformis_, behind the _m. coccygeo-iliacus_,
etc., and above the muscles of the rectum. They arise from the hinder
extremity of the urostyle: they appear to be connected with the
rectal muscles, and pass outwards to be attached to the skin.
Among the cutaneous muscles may perhaps be included the _m.
submaxillaris_ (p. 62).
The fibrils passing from the flexor tendons to the warty bodies on
the plantar surface of the toes are described[50] with the skin
(p. 373).
[Footnote 50: Compare Klein, Beiträge zur Anatomie der ungeschwänzten
Batrachier (R. temporaria, L.): Jahreshefte des Vereins für
vaterländische Naturkunde in Württemberg, 1850, p. 72.]
[Illustration: Fig. 96.
Hind portion of back and thigh of _Rana esculenta_.
_cd_ M. cutaneus dorsi.
_cx._ Coccyx.
_gl._ M. glutaeus.
_H_ Skin reflected to left side.
_oc_ M. obliquus externus.
_rf_ M. rectus femoris anterior.
_sm_ M. semimembranosus.
_v.e_ M. vastus externus.
]
SECTION III.
THE NERVOUS SYSTEM.
THE NERVOUS SYSTEM.
LITERATURE.
*Ahlborn, F.*, Ueber die Bedeutung der Zirbeldrüse. Zeit. f. wiss.
Zool. 1884. Vol. XL, pp. 331–337.
*Allen, H.*, The Spinal Cord in Batrachia and Reptilia. Proc. Acad.
Nat. Sci. Philadelphia. 1883, pp. 56–57.
*Arndt, A. W.*, Untersuchungen über die Ganglienkörper des Nervus
sympathicus. Arch. f. mikrosk. Anat. 1874. Vol. X, pp. 208–241.
*Arndt, R.*, Untersuchungen über die Endigung der Nerven in den
quergestreiften Muskelfasern. Arch. f. mikrosk. Anat. 1873.
Vol. IX, p. 481.
*Arndt, R.*, Untersuchungen über die Ganglienkörper der
Spinalganglien. Arch. f. mikrosk. Anat. 1875. Vol. XI, p. 140.
*Arnold, J.*, Zur Histologie der Lungen des Frosches. Virchow’s Arch.
1863. Vol. XXVIII, p. 433.
*Arnold, J.*, Histologische Verhältnisse des Frosch-Sympathicus.
Centralbl. f. d. med. Wiss. 1864, p. 657.
*Arnold, J.*, Ueber die feineren histologischen Verhältnisse der
Ganglienzellen in dem Sympathicus des Frosches. Virchow’s Arch.
1865. Vol. XXXII, p. 1.
*Arnold, J.*, Die Spinalfasern im Sympathicus des Frosches. Arch. f.
Anat. und Physiol. 1866, p. 398.
*Arnold, J.*, Das Gewebe der organischen Muskeln. Leipzig, 1869; and
Chap. IV in Stricker’s Handbook.
*Arnstein, C.*, and *Gonjaew*, *K.*, Ueber die Nerven des
Verdauungskanals. Bericht. f. Physiol. u. Histologie. Mittheilung.
aus. d. 4 Vers. wissensch. Naturforsch. zu Kasan. Pflüger’s Arch.
d. ges. Physiol. 1874. Vol. VIII, pp. 614–615.
*Aubert, H.*, Die Innervation der Kreislaufsorgane, Hermann’s
Handbuch der Physiologie. Leipzig, 1880. Vol. IV, Pt. I, p. 377.
*Axmann*, De Gangliorum systematicis structura persitiori eiusque
functionibus. Berolini, 1847.
*Axmann*, Beiträge zur mikroskopischen Anatomie und Physiologie des
Ganglien-nervensystems. 1853, p. 20.
*Baculo, B.*, Nuove ricerche intorno l’apparechio ganglionare
intrinseco dei cuori linfatici. Naples, 1885.
*Balfour, F. M.*, Treatise on Comparative Embryology. London, 1880.
*Balfour, F. M.*, Handbuch der vergleichenden Embryologie. Aus dem
Englischen von B. Vetter. Jena, 1880.
*Beale, L. S.*, On the Structure and Formation of the so-called
Apolar, Unipolar, and Bipolar Nerve-cells of the Frog. Phil.
Trans. 1863, p. 543. (Hyla arborea.)
*Beale, L. S.*, Further observations in favour of the view that
nerve-fibres never end in voluntary muscle. Proc. Roy. Soc. 1863.
Abstract in Quart. Journ. Micros. Sci. 1863. Vol. XII, p. 668.
*Beale, L. S.*, New observations upon the structure, etc. of certain
nervous centres. Proc. Roy. Soc. 1860. Vol. III.
*Beale, L. S.*, On the Distribution of Nerves to the elementary
fibres of Striped Muscle. Phil. Trans. 1864, p. 611.
*Beale, L. S.*, Of very fine nerve-fibres ramifying in certain
fibrous tissues and trunks, and plexuses consisting entirely
of very fine nerve-fibres in the bladder of the frog. Beale’s
Archives of Medicine, 1864. Vol. IV, pp. 19–251.
*Beard, J.*, The Ciliary or Motor-oculi ganglion and the Ganglion
of the ophthalmicus profundus in Sharks. Anatom. Anzeiger. 1887.
Vol. II, p. 565.
*Beck, K.*, Zur Kenntniss der Herznerven. Arch. f. mik. Anat. 1885.
Vol. XXIV, pp. 11–19.
*Bellonci, G.*, Intorno alla struttura e alle connessioni dei
lobi olfattorii negli arthropodi superiori e nei vertebrati.
Atti Accad. Lincei Ann. 279 Mem. Accad. Bologna, Vol. XIII,
pp. 555–564: and in Arch. Ital. Biol. 1883; Vol. III, pp. 191–196.
*Bellonci, G.*, Sulla terminazione centrale del nervo ottico nei
mammiferi. Mem. Accad. Bologna, Vol. VI, pp. 199–205: and in Arch.
Ital. Biol. 1884, Vol. VI, pp. 405–411.
*Bidder, F. H.*, Die Endigungsweise der Herzzweige des N. vagus beim
Frosch. Arch. f. Anat. u. Physiol. 1839, p. 1.
*Bidder, F. H.*, Zur Lehre von dem Verhältniss der Ganglienkörper
zu den Nervenfasern. Nebst einem Anhange von Dr. A. W. Volkmann.
Leipzig, 1847.
*Bidder, F. H.*, Zur Lehre vom Verhalten der Ganglienkörper, u. s. w.
Leipzig, 1847.
*Bidder, F. H.*, Ueber functionelle verschiedene und räumlich
getrennte Nerven-centra im Froschherzen. Arch. f. Anat. u.
Physiol. 1852, p. 163.
*Bidder, F. H.*, Endigungsweise der Herzzweige des N. vagus beim
Frosch. Arch. f. Anat. und Physiol. 1868, p. 1.
*Bidder, F. H.*, Zur näheren Kenntniss des Froschherzens und seiner
Nerven. Arch. f. Anat. u. Physiol. 1866, p. 1.
*Bidder, F. H.*, and *Kupffer*, Untersuchungen über die Textur des
Rückenmarks. Leipzig, 1857.
*Bidder, F. H.*, and *Volkmann*, *A. W.*, Die Selbständigkeit des
sympathischen Nervensystems, durch anatomische Untersuchungen
nachgewiesen. Leipzig, 1842.
*Bidder* and *Gregory*, Beiträge zur Physiologie der Herzbewegung
beim Frosche. Dorpat, 1865.
*Bikfalvi, K.*, Ueber die Hornscheide der markhaltigen Nervenfasern.
Orvoster-meszettudomanyi Ertesito, 1884, p. 133. Abstract in
Centralbl. f. d. med. Wiss. 1886, p. 34.
*Biroege, E. A.*, Die Zahl der Nervenfasern u. der motor.
Ganglienzellen im Rückenmark des Frosches. Arch. f. Anat. u.
Physiol. 1882. Physiol. Abth., p. 435.
*Bischoff*, Nervi accessorii Willisii anatomia et physiologia.
Heidelberg, 1832.
*Blasius, G.*, Gerardi Blasii Anatomia Animalium. Amstelodami, 1681.
*Blattmann, A.*, Mikrosk. anatom. Darstellung der Centralorgane des
Nervensystems bei den Batrachiern. Dissert. Zürich, 1850.
*Boll, F.*, Studj sulle immagini microscopiche della fibra nervosa
midollare. Atti della R. accademia dei Lincei, 1876–1877. Vol. II.
*Boll, F.*, Ueber Zersetzungsbilder der markhaltigen Nervenfasern.
Arch. f. Anat. u. Physiol. 1877, p. 288.
*Bojanus*, Testudinis anatomia. 1819.
*Bosse*, De ganglior. spinal. vi in nutr. radic. poster. nervor.
spinal. Dissert. 1859.
*Boveri, T.*, Beiträge zur Kenntniss der Nervenfasern. Abhandl. d.
bayr. Akad. d. Wiss. 1885. Vol. XV, p. 421.
*Bremer, D. L.*, Die Nerven der Capillaren, der kleinen Arterien und
Venen. Arch. f. mik. Anat. Vol. XXI. 1882, p. 663.
*Bremer, L.*, Ueber die Muskelspindeln sowie über Structur,
Neubildung u. Innervation der quergestreiften Muskelfaser.
Waldeyer’s Arch. 1883. Vol. XXII, p. 2.
*Bremer, L.*, Ueber die Endigungen der markhaltigen und marklosen
Nerven im quergestreiften Muskel. Arch. f. mikrosk. Anat. 1882.
Vol. XXI, p. 165.
*Brenner, A.*, Ueber das Verhältniss des nervus laryngeus inferior
vagi zu einigen Aortenvarietäten des Menschen und zu dem
Aortensystem der durch Lungen athmenden Wirbelthiere überhaupt.
His u. Braune’s Arch. 1883, pp. 373–397.
*Budge, J.*, Ueber den Verlauf der Nervenfasern im Rückenmark des
Frosches. Arch. f. Anat. u. Physiol. 1844, p. 160.
*Budge, J.*, Ueber die Bewegung der Iris. (Concerning ganglia of
motor-oculi, p. 36.)
*Budge, J.*, Wagner’s Handwörterb. d. Physiologie. 1846. Vol. III,
p. 451.
*Burdon-Sanderson, J.*, Circulation of the Blood. Handbook for the
Physiological Laboratory. London, 1873.
*Calberla, E.*, Ueber die Endigungsweise der Nerven in den
quergestreiften Muskeln bei Amphibien. Zeit. f. wiss. Zool. 1874.
Vol. XXIV, p. 164.
*Calberla, E.*, Studien über die Entwicklung der quergestreiften
Muskeln und Nerven der Amphibien und Reptilien. Arch. f. mik.
Anat. 1875. Vol. XI, p. 442.
*Carus*, Versuch einer Darstellung des Nervensystems und Gehirns.
Leipzig, 1814.
*Champness, F.*, The septum atrium of the Frog and Rabbit. Journ. of
Anat. and Physiol. 1874.
*Christmas-Dirckinck-Holmfeld, J.*, Experimentaluntersuchungen über
den Bau der Regio olfactoria. Nord. med. ark. 1883. Vol. XV, No. 3.
*Ciaccio, G. V.*, On the nerves of the Cornea, and their distribution
in the corneal tissue of man and animals. Proc. Roy. Soc. 1863.
Abstract in Trans. Micros. Soc. London, 1863. Vol. XI, pp. 77–93.
*Ciaccio, G. V.*, On the distribution of nerves to the skin of the
frog, with physiological remarks on the ganglia connected with the
cerebro-spinal nerves. Quart. Journ. Micros. Sci. 1864. Vol. IV,
pp. 15–31.
*Ciaccio, G. V.*, Intorno alla minuta fabbrica delle pelle Rana
esculenta. Giornale di Scienze naturali ed economiche. Palermo,
1866. Vol. II, p. 103.
*Clarke, J. Lockhart*, Ueber den Bau des Bulbus olfactorius und der
Geruchsschleimhaut. Zeit. f. wiss. Zool. 1862. Vol. XI, p. 31.
*Cornil* and *Ranvier*, A Manual of Pathological Histology. London,
1880, p. 359, Fig. 199 (Ganglia of heart).
*Courvoisier, G.*, Beobacht. über den sympathischen Gränzstrang.
Arch. f. mik. Anat. 1866. Vol. II, p. 13.
*Courvoisier, L. G.*, Ueber die spinalen und sympathischen Zellen des
Frosches. Centralbl. f. d. med. Wiss. 1867, p. 897.
*Courvoisier, G.*, Ueber die Zellen der Spinalganglien, sowie des
Sympathicus beim Frosch. Arch. f. mikrosk. Anat. 1868. Vol. IV,
p. 125.
*Cuvier*, Leçons d’anatomie comparée. 2nd Edit. Vol. II.
*Cyon*, Ueber die Nerven des Peritoneum. Berichte über die
Verhandlungen d. königl. sächs. Gesellsch. d. Wissensch. zu
Leipzig. Math.-physik. Classe. 1868. Vol. XX, p. 119.
*Czermak, J. N.*, Ueber die Hautnerven des Frosches. Arch. f. Anat.
u. Physiol. 1849, p. 252. Leipzig, 1869.
*Czermak, J. N.*, Ueber die Herznerven des Frosches, Rana temporaria.
Arch. f. Anat. u. Physiol. 1851, p. 160.
*v. Darkschewitsch, L.*, Zur Anatomie der Glandula pinealis. Neurol.
Cent. Bl. 1886. Vol. V, p. 29.
*v. Deen*, De differentia et nexu inter nervos vitae animalis et
vitae organicae. Diss. inaugur. Lugduni-Bat., 1834.
*v. Deen*, Over de zijdelingsche Takken dar swervende zenuw van
den Proteus anguineus, aus Bijdragen tot de Naturkundige.
Wettenschappen, 1834.
*v. Deen*, Ueber den Ramus lateralis n. vagi bei den Batrachiern.
Arch. f. Anat. u. Physiol. 1834, p. 477 (abstract from Diss.
inaugur. De differentia et nexu inter nervos vitae animalis et
vitae organicae). Lugduni-Bat.
*Deiters, O.*, Untersuchungen über Gehirn und Rückenmark.
Braunschweig, 1865.
*Denissenko, G.*, Zur Frage über den Bau der Kleinhirnrinde bei
verschiedenen Klassen von Wirbelthieren. Arch. f. mikrosk. Anat.
1877. Vol. XIV, p. 203.
*Dietl, M. J.*, Beobachtungen über Theilungsvorgänge an Nervenzellen.
Wiener Sitzungsber. 1874. Vol. LXIX, Pt. III, p. 71.
*Dietl, M. J.*, Casuistische Beiträge zur Morphologie der
Nervenzellen. Wiener Sitzungsber. 1874. Vol. LXIX, Pt. III, p. 80.
*Dogiel, J.*, Die Ganglienzellen und Nerven des Herzventrikels beim
Frosche. Arch. f. mikrosk. Anat. 1877. Vol. XIV, p. 470.
*Dogiel, J.*, Die Ganglienzellen des Herzens bei verschiedenen
Thieren und beim Menschen. Arch. f. mikrosk. Anat. 1877.
Vol. XVII, p. 471.
*Dogiel, J.*, Die Nervenzellen und Nerven des Herzventrikels beim
Frosche. Arch. f. mikrosk. Anat. 1882. Vol. XXI, p. 21.
*Duméril, A. M. C.*, and *Bibron, G.*, Erpétologie générale ou
histoire naturelle complète des reptiles. Paris, 1841.
*Eberth*, Untersuchungen zur normalen und pathologischen Anatomie der
Froschhaut. Leipzig, 1869.
*Ecker, A.*, Icones physiologicae. Leipzig, 1851 to 1859.
*Eckhard, C.*, Beiträge zur Anatomie und Physiologie. Giessen, 1860.
Vol. II.
*Eckhard, C.*, Experimentale Physiologie des Nervensystems. Giessen,
1867, p. 208 (Ganglion cells of heart).
*Edinger, L.*, Nachtrag zu dem Bericht über Leistungen auf dem
Gebiete der Anatomie des Centralnervensystems. Schmidt’s Jahresb.
1887.
*Egorow, W.*, Ueber die Nervenzellen der Lungen. Centralbl. f. med.
Wiss. 1879. Vol. XVII, p. 305.
*Eichholtz*, De piscium atque amphibiorum nudorum lobis opticis atque
olfactoriis. Berolini, 1841.
*Engelmann, T. W.*, Zur Physiologie des Ureter. Pflüger’s Arch. f. d.
ges. Physiol. 1869. Vol. II, p. 243. (Treats also of histological
details of frog’s bladder.)
*Engelmann, T. W.*, Ueber die Discontinuität des Axencylinders und
den fibrillären Bau der Nervenfasern. Pflüger’s Arch. f. d. ges.
Physiol. 1880. Vol. XXII, p. 1.
*Engelmann, T. W.*, Der Bulbus aortae des Froschherzens. Pflüger’s
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*Remak, R.*, Multipolare Ganglienzellen. Berliner Monatsberichte.
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*Retzius, G.*, Undersökung öson cerebrospinalganglionus nervseller
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THE NERVOUS SYSTEM.
I. THE CENTRAL NERVOUS SYSTEM.
_(Re-written by the translator.)_
A. THE SPINAL CORD (Fig. 97).
*1.* *External form.* The spinal cord is, in comparison with the
brain, somewhat small; the two organs are directly continuous, and
present no distinct line of demarcation: the point of origin of
the first spinal nerve is, therefore, arbitrarily accepted as the
anterior limit of the spinal cord; posteriorly it terminates in the
_filum terminale_.
The spinal cord is flattened dorso-ventrally, and is constricted at
a point (_pars media_, Reissner) somewhat anterior to its middle: in
consequence of this constriction the cord has two enlargements; an
anterior smaller, and a posterior larger (_intumescentiae anterior v.
posterior_), from which arise the nerves of the brachial and lumbar
plexuses respectively. At about the sixth or seventh vertebra, the
hinder enlargement diminishes rather abruptly to form the so-called
_conus medullaris_; this is continued into the _filum terminate_,
which enters the cavity of the urostyle. The hinder portion of the
lumbar nerves forms a _cauda equina_, the constituent nerves of which
surround the _filum terminale_.
A *dorsal longitudinal fissure* (_sulcus longitudinalis superior_)
is well marked in the middle line of the dorsal surface of the
posterior enlargement; anteriorly and posteriorly it rapidly fades
away, its position being merely indicated by a small amount of
connective-tissue and a blood-vessel.
The *ventral longitudinal fissure* (_sulcus longitudinalis inferior_)
is well marked throughout the length of the cord. Neither fissure
can be traced in the hinder part of the _conus medullaris_ or in the
_filum terminale_.
Ten pairs of nerves arise from the spinal cord, each nerve arising
by two roots, a ventral and a dorsal (anterior and posterior), from
points near the ventral and dorsal longitudinal sinuses respectively:
the two roots unite at their point of exit from the vertebral canal
through the intervertebral foramen; each dorsal root possesses a
ganglion.
[Illustration: Fig. 97.
The nervous system of _Rana esculenta_, from the ventral surface.
(From Icones physiologicae by A. Ecker. Pl. XXIV, Fig. 1.)
_F_ Facial nerve.
_G_ Ganglion of pneumogastric nerve.
_He_ Cerebral hemisphere.
_Lc_ Optic tract.
_Lop_ Optic lobe.
_M_ Boundary between medulla oblongata and spinal cord.
_M1–10_ Spinal nerves.
_MS_ Connection between fourth spinal nerve and
sympathetic chain.
_N_ Nasal sac.
_Ni_ Sciatic nerve.
_No_ Crural nerve.
_o_ Eyeball.
_S_ Trunk of sympathetic.
_S1–10_ Sympathetic ganglia.
_Sm_ Rami communicantes of sympathetic.
_Sp_ Continuation of sympathetic into head.
_I_ Olfactory nerve.
_II_ Optic nerve.
_III_ Motor oculi nerve.
_IV_ Trochlear nerve.
_V_ Trigeminal and facial nerves.
_Va_ Ramus ophthalmicus of trigeminal.
_Vc_ Ramus maxillo-mandibularis of trigeminal.
_Vd_ Mandibular branch of trigeminal.
_Ve_ Hyomandibular branch of facial.
_Vg_ Gasserian ganglion.
_Vs_ Upper end of sympathetic trunk in connection with
Gasserian ganglion.
_VI_ Abducens nerve.
_VII_ Facial nerve.
_VIII_ Auditory nerve.
_X_ Glossopharyngeal and pneumogastric nerves.
_X1_ Ramus anterior of glossopharyngeal.
_X2_ Ramus Posterior of glossopharyngeal.
_X3–4_ Branches of pneumogastric.
]
*2.* *Internal structure.* As in other vertebrates, the spinal cord
consists of white and grey matter, the latter being surrounded by
the former; the relative amount of the one to the other varies in
different parts of the cord.
A *transverse* section of the cord presents the same general
characteristics as a similar section from a bird or mammal. The grey
matter lies in the middle, surrounding the central canal, and is
prolonged into each half of the section by ventral and dorsal horns
or _cornua_. The grey matter is surrounded by the white, but is not
so sharply marked off from this in amphibia as in birds and mammals.
A section through the *anterior enlargement* is almost quadrangular
in outline, and somewhat broader below than above; the ventral
longitudinal fissure is well marked and deep, while the dorsal is
indistinct. The dorsal horns are narrow and short, the ventral longer
and much broader. The space between the dorsal horns is narrow and
deep, that between the ventral shallow; the outer boundary of the
grey matter is almost straight, and the central canal is placed above
the centre of the section.
In the *constricted portion* of the cord (_pars media_) the relative
proportion of the white matter is increased at the expense of the
grey; the horns are less distinct, the dorsal being directed outwards
and the ventral somewhat flattened. The central canal is in the
centre of the section.
The *posterior enlargement* shows the ventral horns projecting
outwards, very much enlarged, and approaching the periphery; the
space between them is semilunar. The dorsal horns are well developed,
especially at their upper parts; the space between them is narrow and
deep. The outer margin of the grey matter is again nearly a straight
line. The central canal is below the centre of the section.
The arrangement of the parts in the _conus medullaris_ approaches
that in the _pars media_: the horns are much diminished in size, and
posteriorly they entirely disappear, the ventral horns persisting
longer than the dorsal. The central canal approaches the lower
surface.
No cornua can be recognised in the _filum terminale_ behind the
origin of the last pair of spinal nerves. The grey matter has here
a circular outline, with the exception of a very slight indentation
below; the white matter is almost absent: the central canal is on the
lower border of the section in the anterior part, while posteriorly
it occupies almost the entire space below the _pia mater_.
The *Central Canal* lies in the median line, and always presents a
distinct lumen; in the two enlargements this lumen forms a vertical
ellipse[51], while in the _pars media_ it is circular. The canal is
lined by a single layer of ciliated columnar epithelium, the cells
of which are usually conical, with their bases directed towards the
lumen; but other forms may be noticed. These cells average about
0·040 mm. in length and about 0·002 mm. in width at their broadest
part. The peripheral extremities of the cells have processes, which,
in the case of the cells above and below the cord, may often be
traced as far as the _pia mater_; the processes of the lateral cells
are less distinct and seem to be shorter. Anteriorly the central
canal opens into the floor of the fourth ventricle. The termination
of the central canal, posteriorly, has been described by Masius and
Vanlair. According to these observers, the canal towards the hinder
end of the _filum terminale_ increases very gradually in width, until
its epithelial cells are immediately underneath the _pia mater_,
its walls then converge somewhat more sharply to close the cavity.
From the point where the canal commences to increase in width, a
change takes place in its epithelial wall, which, instead of having a
single layer of cells, now possesses two to three layers; towards the
posterior end it is again thinned out to a single layer.
[Footnote 51: v. Kölliker states that the lumen is everywhere
circular.]
The *grey matter* varies in different parts of the cord and
in different parts of the same section. In a section through
the anterior enlargement a portion of the grey matter, placed
immediately above the central canal, is easily distinguished by its
vertically-placed, elliptical outline, and by its transparency: it
is known as the _substantia reticularis_. It consists of a mesh-work
of branched cells, through which course distinctly contoured fine
commisural fibres which are derived chiefly from the dorsal cornua,
the vertical from the epithelial cells of the roof of the central
canal. In a series of sections the _substantia reticulosa_ may be
seen to originate indistinctly in the most anterior part of the cord;
in the anterior enlargement it already possesses the elliptical form
mentioned, and in the _pars media_ it commences to send off lateral
processes to either side. In the posterior enlargement it reaches
its greatest absolute development, as it here surrounds the central
canal; while further backwards it encroaches until, together with the
remaining grey matter, it constitutes almost the whole of the _filum
terminale_.
Immediately underneath the central canal is a narrow band, which
immediately connects the grey matter of the two sides; above it is
bounded by the epithelium of the central canal, below by medullated
fibres. This _septum medium_ (Reissner) may be traced backwards from
the anterior extremity of the cord to the posterior enlargement. It
consists chiefly of transverse fibres, together with vertical fibres
derived from the epithelial cells on the floor of the canal, and
like the _substantia reticulosa_, is distinguished by its greater
transparency from the rest of the grey matter.
The grey matter consists of connective-tissue and nervous elements,
which are very intimately united; each of these elements including
its special cells and fibres. The *nerve-cells* vary much in size and
appearance. A prominent group of large cells in the ventral cornua,
the *lateral group* (Stieda), is very conspicuous. The individual
cells are seldom rounded, but are usually spindle-shaped or angular,
and each possesses one to five processes, which may often be traced
through considerable distances. These cells have an average length of
0·040 mm., and are about 0·016 mm. broad; they are somewhat larger
in the anterior enlargement than in the posterior, and are also
more numerous in a section from the anterior enlargement than in a
section from the posterior. In the terminal filament they gradually
disappear. Some of their processes are continued into the lateral
columns (Köppen).
Smaller, spindle-shaped or triangular cells are scattered irregularly
throughout the grey matter, without forming distinct groups, though
for descriptive purposes those of the centre have been named the
*central group*. In a stained, transverse section of the cord are
seen numerous *nuclei*; these undoubtedly belong both to small
nerve-cells and to connective-tissue cells, but except under the
most favourable conditions the two are indistinguishable. The larger
nerve-cells present the usual characters of nerve-cells: more or
less granular contents, nucleus, well-marked nucleolus, more or less
marked fibrillation; their processes are usually more homogeneous.
The cells are frequently pigmented.
The *processes* of the cells belonging to the lateral group radiate
in all possible directions, but certain well-marked processes
directed towards the middle line can always be made out. From
the lowest part of this group a few processes may be traced into
the ventral roots. The small cells seem to be chiefly arranged
vertically, although their processes radiate in all directions
(Stieda).
The *Fibres of the grey substance* are nearly all non-medullated.
They may be traced in all directions, but the best-marked groups are
either vertical or transverse. The vertical fibres appear to arise
from the central grey matter, and to ascend in larger or smaller
bundles towards the periphery. The transverse fibres are arranged
chiefly in the two commissures: the dorsal commissure (_commissura
superior_) is the smaller; the fibres are parallel, and show no trace
of decussation; externally they radiate in various directions to
the dorsal horns. The ventral commissure is composed of two layers,
the upper grey (_commissura inferior grisea_), the lower white
(_commissura inferior alba_): both are interrupted by the _septum
medium_. A well-marked decussation of the fibres is seen in the
middle line; the exact mode of termination of these fibres has not
been made out, but many appear to communicate with the large cells of
the ventral horns.
The *white matter* consists chiefly of longitudinal, medullated
fibres, in which various columns may be distinguished. The dorsal
columns are separated from the lateral by a process of neuroglia,
continued from the general investment of neuroglia lying under the
_pia mater_. The line of separation between the lateral and ventral
columns is not well marked; it is about the line which would be
formed by prolonging the ventral horns to the surface.
The fibres vary in size, and fibres of all sizes may be found in any
particular part of a transverse section; still the fibres of the
ventral columns have an average greater diameter than those of the
lateral columns, and the fibres of the dorsal columns are finer than
those of the lateral. The largest fibres of the ventral column are
placed near the ventral fissure and on its lower border; they attain
their greatest development in the posterior enlargement; these fibres
frequently contain two or three axis-cylinders each. Köppen suggests
that they may represent the _formatio reticularis_ of higher animals.
In the lateral columns the larger fibres are placed close to the
grey matter, these columns also receive fibres from the cells of the
lateral group.
In the dorsal columns the radiating root-fibres never reach the
median plane, but leave an area of purely longitudinal fibres on each
side of the dorsal fissure; these represent Goll’s columns, and have
a club-shaped outline in transverse section.
The white matter is pierced in all directions by fine
connective-tissue fibres and bundles of fibres which radiate from
the grey matter; some branch and join with others to form a network,
others pass almost uninterruptedly to the periphery. From the
connective-tissue cells of the _pia mater_, processes pass into the
white matter and assist in completing the connective-tissue matrix
for the nervous elements.
*Dorsal roots* of the spinal nerves. Each root consists of a single
bundle of nerve fibres, which suddenly bends at the periphery of the
cord in order to descend vertically through the white matter towards
the dorsal horn; the fibres divide into three sets, one to the dorsal
commissure, a second to the upper horn itself, and the third helps to
form the dorsal columns.
*Ventral roots* of the spinal nerves. Each ventral root consists of
three or four delicate threads, which may be traced to the ventral
cornua, which they reach after a vertical or very slightly oblique
course through the white matter. Other fibres arise from the ventral
columns, but these oblique fibres never extend to the median plane.
*Pigment* is found distributed irregularly through a section from any
part of the spinal cord; it is increased in amount in those parts in
which there is an increased amount of grey matter. The pigmentation
is always found more marked in the lower parts of the ventral horns
than in other parts.
B. THE BRAIN (Figs. 98, 102, 103, and 105).
*1.* *General description.* From behind forwards, the *dorsal*
surface of the brain presents the following parts for examination:
the _medulla oblongata_, the _cerebellum_, the optic lobes, the
thalamencephalon, the cerebral hemispheres, and the olfactory lobes.
The _medulla oblongata_ is a direct continuation of the spinal cord;
it is wider anteriorly than posteriorly, and is separated in front
from the optic lobes by a vertical plate of nervous matter, the
_cerebellum_. The optic lobes are two symmetrical ovoid bodies touching
each other in the median plane, and together forming the widest part
of the brain. In front of the optic lobes is the thalamencephalon,
with a thick vascular membrane, the choroid plexus, lying on its upper
surface, and connected with the pineal gland; the thalamencephalon
extends forwards between the posterior ends of the cerebral
hemispheres. The cerebral hemispheres are two symmetrical ovoid bodies,
narrow in front, wider and slightly diverging behind: each hemisphere
is prolonged forwards to form an olfactory lobe.
The *ventral* surface has in front the olfactory lobes, then the
cerebral hemispheres, behind these the _lamina terminalis_, the _tuber
cinereum_, the optic chiasma, the pituitary body, the _crura cerebri_,
and lastly the _medulla oblongata_, in the order here given.
The various *cranial nerves* (Figs. 102 and 103) may be seen to arise
as follows:--The olfactory nerve (_I_, _I_′, _L.ol_′) arises directly
from the anterior end and outer side of the corresponding olfactory
lobe, and from the cerebral hemisphere. The optic nerve (_To_ and
_II_) arises, as the optic tract, from the side of the brain below the
optic lobe, whence it passes to the chiasma on the under surface of
the brain. The oculo-motor (_III_) takes its origin from the ventral
surface close to the median line and between the _crura cerebri_.
The pathetic or trochlear nerve (_IV_) is attached to the dorsal
surface between the optic lobes and the _cerebellum_. The trigeminal
nerve (_V_) arises from the side and anterior part of the _medulla
oblongata_. The _abducens_ (_VI_) arises behind the pituitary body
close to the median line from the ventral surface of the medulla
halfway between the _sulcus_ and the origin of the _vagus_. The
facial and auditory (_VII_ and _VIII_) nerves arise from the _medulla
oblongata_ behind the trigeminal nerve, the facial being in front of
the auditory nerve. The glossopharyngeal (_IX_) nerve arises, in common
with the pneumogastric nerve (_X_), behind the auditory nerve.
*2.* *The several parts of the brain.*
*a.* The _medulla oblongata_ (Figs. 98, 102, and 103 _Mo_)--α.
*External form.* The _medulla_ is limited behind by the origin of the
first pair of spinal nerves, at which point a very faint constriction
is sometimes found: it extends forwards as far as the _cerebellum_. It
gradually widens as it passes forwards until just before it reaches its
anterior limit, where it presents a shallow but sharp constriction. The
*dorsal surface* is characterised by the presence of a deep, triangular
fossa, the *fourth ventricle* (Fig. 98 _S.r_), (_ventriculus quartus_,
Stieda; _sinus rhomboideus s. sinus triangularis_, Reissner; _fossa
rhomboidalis_); the sides of the triangle are, however, not quite
straight, but are slightly bent outwards just before they converge
towards the posteriorly-directed apex; the base of the triangle is
formed by the _cerebellum_. By careful examination, the ventricle is
seen to be continued for a short distance under the _cerebellum_,
where it opens into the Sylvian aqueduct. In the floor of the fourth
ventricle is a well-marked median longitudinal fissure (_sulcus
centralis_), (Fig. 98 _S_). Into the posterior part of the ventricle
opens the central canal of the spinal cord. As the fourth ventricle is
formed by the white matter passing to either side, and the simultaneous
flattening of the grey matter, the floor of the fourth ventricle is
composed of grey matter.
The fourth ventricle is closed in by a highly vascular membrane,
the *choroid plexus* of the fourth ventricle (_plexus choroideus
ventriculi quarti_, Reissner; _velum medullare posterius_). The
blood-vessels of the plexus will be described together with the
other vessels of the brain (p. 162). They are supported by a
connective-tissue matrix, and the whole covered with flattened
epithelium, which in the fourth ventricle is ciliated and often
pigmented.
The *ventral surface* of the _medulla oblongata_ (Fig. 102 _Mo_) has
a median ventral longitudinal fissure, a direct continuation of that
of the cord; in the anterior part of the _medulla oblongata_ there is
also to either side of this a lateral fissure, continued on to the
_crura cerebri_; these fissures correspond to the positions of the two
_rami posteriores_ of the internal carotid arteries; they are always
well seen in microscopical sections. The _medulla oblongata_ is so
intimately connected with the _pars commissuralis_ (pp. 149, 150) that
the minute anatomy of the two is best described at the same time.
β. *Internal structure.* Examined by means of serial sections, the
_medulla oblongata_ is seen to have, in comparison with the cord, an
increased amount of grey matter; this is especially the case in its
anterior part. The floor and inner parts of the walls of the ventricle
are formed of grey matter, in which the largest-sized cells have
disappeared, to be replaced by medium-sized cells. Traced from behind,
the ventral horns of the cord are seen to increase in size and to be
more widely separated until they form two isolated masses, while the
dorsal horns gradually diminish; at the same time they are forced
outwards and upwards, until they lie under the floor of the ventricle,
and so extend to the _pars peduncularis_.
[Illustration: Fig. 98.
Dorsal view of brain of _Rana esculenta_.
_Ad_ Choroid plexus.
_C_ Cerebellum.
_f_ Groove between cerebral hemispheres and olfactory lobes.
_G_ Opening in the roof of the third ventricle.
_Gp_ Pineal body.
_Hc_ Cerebral hemispheres.
_I_ Olfactory nerve.
_Li_ Wall of fourth ventricle.
_L.ol_ Olfactory lobe.
_L.op_ Optic lobe.
_Mo_ Medulla oblongata.
_S_ Longitudinal fissure of the fourth ventricle.
_S.r_ Fourth ventricle.
_Tho_ Thalamencephalon.
]
*Grey matter.* The _substantia reticularis_ is not present, but the
_septum medium_ extends forwards as far as the _pars peduncularis_.
The central canal extends upwards at the expense of the tissue above
it, and is here pear-shaped; at the same time the dorsal longitudinal
fissure deepens until the two meet in the fourth ventricle; beyond this
point one cannot speak of dorsal and ventral horns.
[Illustration: Fig. 99.
Transverse section through hinder end of _Medulla oblongata_ (magnified
30–80)[52], from Stieda.
[Footnote 52: In these diagrams, from Ludwig Stieda’s Studien über das
centrale Nervensystem der Wirbelthiere, the outline of the diagram is
magnified thirty times, while the details are magnified eighty times.]
_b_ Inferior commissure.
_f_ Dorsal horns.
_g_ Ventral horns.
_h_ Fourth ventricle.
_i_ Nucleus centralis.
_k_ Isolated mass of grey matter in which longitudinal
fibres of the pneumogastric nerve course.
]
Small nerve cells are irregularly distributed throughout the whole of
the grey matter and cannot be grouped; the larger cells, on the other
hand, are arranged in distinct groups which have special relations with
the nerves arising from the part. Occasionally these groups are not so
isolated as usual; in this case processes of one group can be traced
into another group (Reissner). Of these groups the chief are:
1. The _nucleus centralis_ (upper inner group, Reissner), _nucleus
medullae oblongatae_, Stieda (Fig. 99 _i_), is a group of cells found
towards the hinder end of the _medulla oblongata_, on either side of
and below the central canal; the group can be traced under the floor
of the fourth ventricle to about its middle. The cells are rounded or
spindle-shaped, the processes directed upwards, downwards, or outwards;
their average size is 0·040–0·048 mm. long by 0·020 mm. broad.
2. The *auditory nucleus* (_nucleus acusticus_, Reissner, Stieda),
(Fig. 100 _n_) is a large group of cells found in the wall of the
fourth ventricle opposite the point of origin of the auditory
nerve. The cells are rounded, pear-shaped, or of spindle form, and
interspersed between the nerve fibres; these cells have an average
length of 0·040 mm., and are about half as broad. The fibres of the
auditory nerve radiate from their superficial origin in all directions
through the grey matter towards these cells, and evidently communicate
with them (Fig. 101 _p_). One small group (Fig. 101 _r_) passes to
a lower level than the rest, and is regarded by Stieda as the true
auditory centre. Köppen considers that the auditory nerve has a
threefold origin: (1) from small cells on the median surface of the
auditory area; (2) from the large cells between the above; (3) from a
group of free nuclei on the dorsal surface of the auditory area.
[Illustration: Fig. 100.
Transverse section through the _Medulla oblongata_ at the point of
origin of the abducens nerve, from Stieda. (Magnified 30 x 80.)
_h_ Fourth ventricle.
_m_ Abducens nerve.
_n_ Auditory nucleus.
_o_ Abducens nucleus.
]
3. The *trigeminal nucleus* (_nucleus trigeminus_), (Fig. 101 _q_) lies
in part beneath the auditory nucleus but extends further forwards. It
forms a rounded group of cells placed under the outer angle of the
grey matter. The cells are somewhat crowded together, and are chiefly
of an elongated spindle-form, with their processes directed obliquely
downwards and outwards. The fibres of the trigeminal nerve separate
into two groups; the upper group is best traced in a horizontal
section, the fibres curving round to join the longitudinal fibres
continued from the dorsal columns of the cord. The fibres of the lower,
smaller group pass transversely inwards to the trigeminal nucleus.
According to Reissner the latter fibres are motor, the former sensory.
Probably other nerves are connected with the hinder part of this group.
4. The *abducens nucleus* (Fig. 100 _o_). From its superficial origin,
the fibres of the abducens nerve may be traced vertically upwards to a
small, rounded, grey mass; at this point the mass is somewhat isolated,
but further forwards it may be traced as belonging to the central grey
matter; it contains small spindle cells.
[Illustration: Fig. 101.
Transverse section of the _Medulla oblongata_, at the point of origin
of the auditory nerve, from Stieda. (Magnified 30 x 80.)
_h_ Fourth ventricle.
_n_ Auditory nucleus.
_o_ Abducens nucleus.
_p_ Auditory nerve.
_p_′ Ganglion of auditory nerve.
_q_ Hinder portion of trigeminal nerve.
_r_ Bundle of fibres arising from trigeminal nucleus
and joining the auditory nerve.
]
5. The *pneumogastric nucleus*. The pneumogastric, with its numerous
irregular roots, arises from the side of the _medulla oblongata_. The
hindermost fibres can be traced as a small bundle, passing almost
transversely through the white matter to the outer margin of the grey
matter. The larger portion of the fibres is placed in front of these;
part of this seems to be directly continuous with the longitudinal
fibres of the white matter; a second part, however, can be traced from
the surface transversely through the white matter to the grey matter.
These latter fibres, together with those of the group first described,
do not arise from the grey matter in this part of the _medulla
oblongata_, but curve round and run backwards longitudinally through
the grey matter, thus forming a rounded bundle of fibres (Fig. 99 _k_).
Between these fibres are interspersed small nerve-cells and nuclei
which disappear as the fibres approach the white matter. The vagus
undoubtedly receives fibres from the grey matter throughout a long
course, and again receives a large bundle just before leaving the grey
matter. The more exact origin of the various fibres has not been traced.
6. The _nucleus magnus_ (Reissner and Stieda) is a very peculiar group
of cells placed on either side, in the most anterior portion of the
_pars commissuralis_, that is, immediately underneath the _valvula
cerebelli_. The large cells are arranged in a transverse section in a
single row so as to enclose a pear-shaped space on either side, which
has its long axis directed from above, downwards and outwards, the
narrower end being above. In longitudinal section the line of cells is
seen to be open in front. The space enclosed by these cells is occupied
by a granular ground-substance which contains only few nuclei. Bellonci
is of opinion that these nuclei represent the _corpora quadrigemina
posteriora_ of higher animals.
*White matter.* In the hinder part of the _medulla oblongata_ the
arrangement of the white matter resembles that of the white matter
of the spinal cord; further forwards the white matter of the dorsal
surface commences to pass to either side, and ultimately it forms the
outer part of the walls of the fourth ventricle. The fibres of the
white matter of the ventral surface are unchanged in direction as they
proceed forwards. The fibres of the anterior part of the medulla are
thinner than those of the posterior portion (Stieda), according to
Reissner they gradually thin as they pass forwards. The fibres are
nearly all longitudinal, such transverse and oblique fibres as are
present being chiefly in connection with the various nerve-roots and
the commissures.
The _commissura superior_ is naturally lost in consequence of the
opening of the central canal into the fourth ventricle; the _commissura
inferior_ is increased in the anterior half and decreased in the
posterior half of the _medulla oblongata_; in the latter the fibres
become more and more oblique, and decussate very freely; ultimately
they seem to be either continued as longitudinal fibres or to join the
ganglia.
Near the _pars commissuralis_ is a transverse arched band of fibres,
passing from the under surface of one half of the cord over the ventral
longitudinal fissure through the _septum medium_ to the under surface
of the opposite half; part of the fibres are continued upwards along
the periphery to the _cerebellum_, part to the _nucleus magnus_.
Vertical, straight, or slightly arched fibres are found in the walls of
the fourth ventricle.
A section from the _medulla oblongata_ has a larger amount of *pigment*
than a section from the spinal cord, and the anterior portion of the
_medulla oblongata_ contains more than the posterior portion. The
pigment is chiefly found in a curved line, placed in the lower and
outer parts of the grey matter; the amount present varies in different
specimens.
*b.* The _Cerebellum_ and _Valvula cerebelli_.
α. *External form.* The _cerebellum_ is a thin, semilunar plate,
which projects between the optic lobes and the fourth ventricle, its
base covering the most anterior part of the ventricle; the posterior
surface possesses a very faint median fissure (Reissner). The _valvula
cerebelli_ (_Velum medullare anterius_, Reissner) is the thin lamella
which connects the anterior surface of the _cerebellum_ with the optic
lobes.
β. *Minute structure.* By means of longitudinal, vertical sections,
the posterior surface of the _cerebellum_ is seen to be covered with
epithelium; in the lower part of the surface this is columnar or
conical, above it is flattened: immediately beneath, that is in front
of this is a finely granular layer, with very closely packed and
granular nuclei. In front of these is a stratum of nerve-fibres forming
the second layer of the cerebellum.
Still more anteriorly is the third layer of the cerebellum, an
irregular double layer of large cells (Purkinje’s cells, Denissenko);
the cells have an average length and breadth of 0.040 mm. and 0.015 mm
respectively; they are pear-shaped or of spindle-form, and possess
usually two well-marked processes, one passing into the layer behind,
the other forwards into the anterior layer to be immediately described,
while other less distinct processes radiate irregularly in all
directions. The fourth and most anterior layer of the cerebellum is a
thick stratum of nerve fibres with numerous nuclei (0.006 to 0.008 mm.
diameter). The fibres are for the most part arranged transversely, but
some course in various directions. These fibres underlie the flattened
epithelium which covers the anterior surface of the cerebellum.
The fibres of the second layer course, for the most part, in an almost
vertical plane; they connect the _cerebellum_ with the optic lobes
(_processus cerebelli ad corpora bigemina_) and with other parts of the
brain.
The fibres of the fourth layer receive numerous long processes from the
large cells of Purkinje; they form a large commissural system, which
can be followed ventrally on each side into the _pars commissuralis_.
A part of the fibres ends here in the grey matter, a second portion
enters the auditory area and forms a descending auditory root, a third
part joins the lateral columns (in the _medulla oblongata_), and
more anteriorly some join the ventral columns. The descending fibres
from the _cerebellum_, together with the _fibrae arcuatae_ found in
the ventral columns, indicate the presence of a _pons Varolii_. The
fibres of this ventral commissure decussate only on its dorsal surface
(Köppen).
The _Valvula cerebelli_ contains a few medullated fibres and the roots
of the trochlear nerves; these pass from the _medulla oblongata_ into
the _valvula cerebelli_, cross in the median line, and then proceed
forwards as the trochlear nerves.
The *pigment* in the _pars commissuralis_ is arranged in a curved line
similar to that found in the _medulla oblongata_, but the line is
shortened at either extremity, and consequently does not extend into
the _cerebellum_.
*c.* The *optic lobes* and _Crura cerebri_. (_Corpora geminata_ and
_Pars peduncularis_, Reissner; _Lobus opticus_, Stieda; Vierhügel,
Tiedemann; Vierhügel (Zweihügel) and _Pedunculi cerebri_, Schiess;
Mesencephalon, Huxley.)
[Illustration: Fig. 102.
Ventral view of brain of _Rana esculenta_.
_Cho_ Optic chiasma.
_Hc_ Cerebral hemispheres.
_Hy_ Pituitary body.
_L.ol_ Olfactory lobe.
_L.ol^1_ Origin of olfactory nerve from
the cerebral hemisphere.
_Lt_ Lamina terminalis.
_Mo_ Medulla oblongata.
_To_ Optic tract.
_Tu.c_ Tuber cinereum.
_I_ 1st }
_I^1_ 2nd } root of the olfactory nerve.
_II_ Optic nerve.
_III_ Oculo-motor nerve.
_IV_ Trochlear nerve.
_VI_ Abducens nerve.
_V_, _VII_, _VIII_ Trigeminal, facial, and
auditory nerves.
_IX_, _X_, _XI_ Glossopharyngeal, pneumogastric,
and accessory nerves.
]
α. *External form* (Figs. 98, 102, 103 _L.op_). The optic lobes are two
prominent ovoid bodies placed immediately in front of the _cerebellum_,
and connected with it by the _valvula cerebelli_; posteriorly they
touch each other in the median plane, while anteriorly they diverge
and thus constitute the widest part of the brain; in the angle thus
formed is the thalamencephalon. The optic lobes are always more darkly
pigmented than any other part of the central nervous system.
[Illustration: Fig. 103.
Lateral view of brain of _Rana esculenta_.
_Ad_ Choroid plexus.
_C_ Cerebellum.
_Gp_ Pineal body.
_Hc_ Cerebral hemisphere.
_Hy_ Pituitary body.
_L.ol_ Olfactory lobe.
_L.ol_^1 Disc at origin of second root.
_L.op_ Optic lobe.
_Mo_ Medulla oblongata.
_Tho_ Thalamencephalon.
_To_ Optic tract.
_Tu.c_ Tuber cinereum.
_I_ 1st }
_I^1_ 2nd } root of olfactory nerve.
_II_ Optic nerve.
_IV_ Trochlear nerve.
_V_ Trigeminal nerve.
_VII_ Facial nerve.
_VIII_ Auditory nerve.
_IX_, _X_, _XI_ Glossopharyngeal, pneumogastric,
and accessory nerves.
]
The _Crura cerebri_ are two columns of white matter, placed beneath
the optic lobes, and partly hidden by the pituitary gland. At their
junction with the _medulla oblongata_, or rather with the _pars
commissuralis_, is a very slight transverse fissure; at the same point
the ventral longitudinal fissure is interrupted by an extremely small
grey tubercle (Stieda).
β. *Internal structure.* From the anterior extremity of the fourth
ventricle a canal, the Sylvian aqueduct (_Aqueductus Sylvii_, _iter
a tertio ad quartum ventriculum_), may be traced forwards under the
cerebellum, in the median line of this section of the brain. At about
opposite the middle of the length of the optic lobes the canal is
dilated and communicates with the cavities or ventricles (_Ventriculi
lobi optici_, Stieda) enclosed by these; a general cavity is formed,
which in transverse section has something of the form of the letter T.
The roof of the cavity is thinner than the floor; this is especially
the case in the median plane opposite the superior longitudinal fissure
between the optic lobes; the floor is thinned in the middle line by the
descending portion of the cavity. The cavity of each optic lobe extends
both forwards and backwards beyond its point of communication with the
dilated Sylvian aqueduct, hence in a transverse section taken in front
of this point (Fig. 104 _h_′) the cavity of either side appears to be
isolated; in a horizontal and longitudinal section (Fig. 105 _Aq_) the
general arrangement of the parts may be well seen.
The grey matter is chiefly arranged in a layer so as to surround the
cavity (Fig. 104), this layer being deeper on either side of the
descending portion of the cavity than elsewhere. For the rest the grey
matter is much interspersed among the white matter, except at the
circumference of the section, which is entirely formed of white matter.
It contains a large number of small cells, of which the nuclei are
alone visible; in the parts mentioned where the layer is most marked
these cells are arranged in oblique rows, between which pass fine
bundles of medullated fibres (Fig. 104, between _u_ and _h_′). A group
of large cells (Fig. 104 _u_) is found on either side of the middle
line and under the floor of the cavity; the cells are about 0.032 mm.
long, and 0.016 mm. broad; the oculo-motor nerve may be traced to
this group, which is the *oculo-motor nucleus*. A small commissure of
decussating fibres connects the nuclei of opposite sides (Köppen).
[Illustration: Fig. 104.
Transverse section through the anterior portion of the optic lobes
opposite the origin of the motor-oculi nerve; from Stieda (magnified
30–80).
_h_ Lower portion of cavity.
_h_′ Lateral portion of cavity.
_u_ Ganglia of oculi-motor nerve.
_v_ Oculo-motor nerve.
_w_ Large cells of the optic lobe.
_x_ Roof of optic lobe.
_y_ Posterior commissure.
_z_ Anterior diverticulum of the cavity.
]
The substance of the roof of the optic lobes (Fig. 104 _x_) is arranged
in very distinct layers: above is a layer free from cells; the fibres
of this layer are extremely fine and delicate, and have not been
accurately traced; under this is a nuclear layer; a second layer of
fine fibres follows, which is succeeded by a second layer of nuclei in
a granular matrix, and lastly epithelium (Stieda). (Reissner describes
three nuclear layers in _Bufo variabilis_, and this is also the case in
_R. temporaria_, G. H.; according to Köppen, the number is variable.)
In the anterior portion of the roof a distinct bundle of fibres may be
made out; externally they bend downwards, and can be traced as far as
the _crura cerebri_.
Fibres corresponding with the commissural and arched fibres of the
_medulla oblongata_ are continued into the hinder portion of the _crura
cerebri_, the change from _pars commissuralis_ to _crura cerebri_ being
very gradual. The longitudinal white fibres are much increased in
number in the _crura cerebri_, and a portion of them can be traced to
the _nucleus magnus_.
A peculiar irregular group of large cells (Fig. 104 _w_) is found where
the roof meets the _crura cerebri_; these vary in diameter from 0.024
to O.040 mm., and their processes are very indistinct.
The fibres of the optic tracts arise, according to Köppen, from two
different origins: the one lies on the hindermost part of the optic
lobe; from this point the fibres curve downwards and forwards to form
longitudinal fibres; this root Köppen names the ventral ascending root,
it can be traced through the entire length of the organ. The second
root arises in the _tectum opticum_ near the longitudinal fissure; it
is smaller than the foregoing, and has been named the dorsal ascending
optic root. The fibres of these two roots unite anteriorly near the
posterior commissure, at which point they receive additional fibres
(Köppen). Bellonci traces a large proportion of the fibres of the optic
tract to the _nucleus magnus_, which pair of nuclei, as already stated,
he regards as the posterior pair of _corpora quadrigemina_ of higher
animals.
The _pars peduncularis_ is the continuation of the _pars commissuralis_
underneath the optic lobes; a gelatinous mass lying in the median plane
and containing numerous isolated nuclei (_Ganglion interpedunculare_)
divides it into two lateral halves. The longitudinal fibres are
ungrouped posteriorly, but arranged in rounded strands in the middle,
especially dorsally; anteriorly the grouped arrangement is lost and the
number of fibres diminished.
The *pigment* of this region has, in a transverse section, an outline
which has something the form of a lyre; commencing on either side of
the median line, and underneath the deepest portion of the cavity,
the pigment line passes, first, directly outwards; then suddenly turns
upwards and slightly outwards parallel with the wall of the deeper part
of the cavity; it then curves outwards to pass below the cavity of the
optic lobe, where it divides, one portion passing outwards, the other
between the Sylvian aqueduct and the ventricle of the optic lobe.
*d.* The *Thalamencephalon* (Huxley), (_Lobus ventriculi tertii_,
Stieda; _Thalami optici_, Reissner; _Thalamus opticus s. Lobus
ventriculi tertii_, Stannius; Ganglien der Haemisphaeren, Carus).
α. *External form.* From above (Fig. 98 _Tho_) the thalamencephalon
is seen as a lozenge-shaped mass lying in front of the optic lobes,
and behind and between the diverging posterior ends of the cerebral
hemispheres; it is covered by a thick vascular membrane, the *choroid
plexus*, through which passes the pedicle of the *pineal body*
(_Glandula pinealis_). On removing the choroid plexus a small aperture
is seen in the roof of the thalamencephalon, connecting the hollow
pedicle of the pineal gland with the *third ventricle*. The ventricle
appears as a narrow slit in the median line, its walls being formed
by the optic thalami. By pressing aside the cerebral hemispheres the
*posterior commissure* (_Commissura posterior_) may be seen lying quite
in front and deep in the cleft of the ventricle. Immediately behind the
pedicle of the pineal body is a slight but well-marked depression (Fig
98 _G_), the origin of which has not been investigated (Wiedersheim).
The choroid plexus is continued forwards between the cerebral
hemispheres (Figs. 98, 103 _Ad_) for some distance, and terminates in a
fine thread of connective-tissue.
The under surface of the thalamencephalon (Fig. 102) is divided
into two parts by the *optic chiasma* (_Cho_): the anterior portion
(_Lt_) is the _lamina terminalis_ (_Substantia cinerea anterior_);
the posterior (_Tu.c_) the _tuber cinereum_. The _lamina terminalis_
is bounded on either side by the cerebral hemispheres. The _tuber
cinereum_ (Figs. 102, 103 _Tu.c_) is a small median swelling
immediately behind the optic chiasma, and caused by the depression
of the floor of the third ventricle to form the _infundibulum_
(_Diverticulum infundibuli_, Reissner).
[Illustration: Fig. 105.
Horizontal section through the brain to show the ventricles.
_Aq_ Ventricles of optic lobes and the aqueduct of Sylvius.
_Dv_ Third ventricle.
_MF_ Foramen of Monroe.
_Sv_ Lateral ventricle.
_Vv_ Fourth ventricle.
]
The *pituitary body* (_Hypophysis cerebri_) is a flattened sac, placed
behind the _tuber cinereum_ and continuous with it by means of the
_infundibulum_.
β. *Internal structure.* The aqueduct of Sylvius, after communicating
with the ventricles of the optic lobes, again contracts (Fig. 105),
but still remains somewhat larger than before. In the thalamencephalon
the Sylvian aqueduct opens into the third ventricle, which gradually
assumes the form of a vertical slit with the walls bulging slightly
outwards in their upper parts. The thin roof of this ventricle, where
complete, contains a band of transverse fibres. The floor is depressed
both before and behind the part immediately above the optic chiasma,
the posterior depression lying above the _tuber cinereum_, which here
descends towards the _infundibulum_: a transverse section through this
portion of the third ventricle has the form of a square standing on one
angle, the superior angle being produced into the vertical slit of the
general cavity. The anterior depression is formed by the general cavity
being prolonged downwards and forwards to the _lamina terminalis_ in
the form of a narrow and shallow slit.
The white and grey matter of the thalamencephalon are only so far
distinct in that the portion immediately surrounding the cavity is
darker than the rest of the section. In the immediate neighbourhood
of the cavity are many small cells and nuclei, which become scarcer
further from the ventricle; they are arranged in rows, separated by a
fibrillated matrix. On either side is a distinct bundle of longitudinal
fibres, the ‘round bundle’ of Köppen, which come from the optic lobes
but appear to arise from either the _pars commissuralis_ or the
_medulla oblongata_, and to receive additional fibres from the optic
thalami; they pass forwards to the base of the cerebral hemispheres
(Stieda). A second set of longitudinal fibres arises in the substance
of the _tuber cinereum_ and passes forwards to the hemispheres (strand
of the _Tuber-cinereum_ and _Thalamus_, Köppen); this band, together
with the ‘round bundle,’ form a _crus cerebri_ (Köppen).
The commissural fibres of the thalamencephalon are: (1) a _commissura
transversa Halleri_ in the posterior portion of the organ; (2) an optic
commissure, consisting of fibres arising from the thalamencephalon
(thalamencephalic root) and crossing the median line to join the optic
tract of the opposite side; (3) a probable commissure between the optic
nerves just in front of the _chiasma opticorum_; the existence of the
latter is not yet proved beyond doubt; (4) the large commissure of
transverse fibres found in the roof of the third ventricle; whether the
fibres decussate or not is uncertain (Köppen).
The fibres of the large commissure of the roof are, in part, continued
into the strand of the _Tuber-cinereum_ above mentioned, and thus
conducted to the posterior parts of the hemispheres (Köppen). A group
of fibres (Meynert’s band, Köppen) is found in each lateral wall of
the third ventricle; they pass from the region of the _nucleus parvus_
downwards in a curved course almost parallel with the external border
of the thalamencephalon.
A distinct group of cells may be noted in this section of the brain,
an arciform or circular group (_Nucleus parvus_, Reissner; ganglion
of the _habenula_, Köppen) of large spindle cells (average diameter
0.016 mm.), placed under the upper border close to the third ventricle;
the group extends alongside the whole length of the ventricle. A second
group lying in the middle and posterior parts beneath the ventricle,
Köppen names the ‘ventral nucleus’ of the thalamencephalon.
The *pigment* in the posterior part of the thalamencephalon is arranged
in a manner similar to that in the optic lobes and _crura cerebri_;
anteriorly where the third ventricle is prolonged forwards and
downwards the arrangement is different; the pigment lies in a curved
line above the process of the ventricle, with its concavity directed
downwards, each end bifurcating, in order that one branch may pass
upwards, the other downwards.
The *pineal body*[53] is a small vesicle placed underneath the skin
above the fronto-parietal bones; in the embryo it is connected with
the third ventricle by means of the pedicle[54] already mentioned; the
skin covering the body is always paler than the surrounding skin, and
the usual cutaneous glands are absent in this part; the paler spot on
the head may always be found, but is more distinct in _Rana temporaria_
than in _Rana esculenta_. The structure on the roof of the third
ventricle, which is usually known as the pineal body, is nothing more
than a thickened portion of the choroid plexus, and consists of a group
of convoluted vessels surrounded by _pia mater_, which is described
by Wyman as being covered with ciliated epithelium (_R. pipiens_).
The true pineal body is a small body with an outer connective-tissue
capsule, derived from the _pia mater_; this encloses an irregular
mass of epithelial cells; according to de Graaf a twig of the _ramus
supramaxillaris_ reaches it subcutaneously, and a blood-vessel
accompanies the pedicle through the _foramen parietale_. According to
Darkschewitsch, the pedicle contains medullated nerve-fibres derived
directly from the brain.
[Footnote 53: Compare Ehlers, Ueber die Zirbel der Haifische, Zeit.
f. wiss. Zool. 1878, Vol. XXX; and Balfour, Development of the
Elasmobranch Fishes, chap. ix.]
[Footnote 54: Wiedersheim states that the pedicle is hollow, and
regards the part formerly known as the pineal body as a thickened
portion of this pedicle.]
The *pituitary body* (Figs. 102, 103 _Hy_) when examined with a lens
is seen to consist of two portions: an anterior, superior, and smaller
white portion, and a larger, inferior, posterior, and reddish portion.
The anterior portion has the form of a very small, flat disk, and is
enclosed in a connective-tissue capsule which sends in larger and
smaller processes. In either transverse or longitudinal section it
is seen to be formed of two horizontal layers separated by a line
of blood-vessels and connective-tissue. The upper layer consists of
a granular and reticular matrix, containing many nuclei (averaging
0.006 to 0.010 mm. diameter), and divided into irregular rounded or
polyhedral spaces by bands of tissue derived from the capsule. This
layer is more vascular than the lower. The lower layer consists of
a mass of clear, nucleated rounded or polyhedral cells (0.016 to
0.024 mm. in diameter; nuclei from 0.008 to O.012 mm. in diameter,
Reissner), pierced by very fine connective-tissue septa derived
from the capsule. The septa are, for the most part, vertical and
longitudinal (Reissner), the blood-vessels are very few.
The posterior larger portion of the pituitary body (Fig. 106) is also
compressed from above downwards, and in transverse section as an oval
outline. It possesses an external thin connective-tissue capsule,
which sends in fine processes to support a mass of convoluted tubes,
between which course a few blood-vessels; these tubes possess an outer
nucleated basement-membrane, and are lined with a single layer of
more or less cylindrical epithelium, which entirely fills the tube;
hence the tubes possess no lumen. The tubes are from 0.04 to 0.08 mm.
in diameter; the cells are clear or granular, and possess distinct,
rounded nuclei.
*e.* The *Cerebral Hemispheres* and *Olfactory Lobes*. The cerebral
hemispheres (_Lobi hemisphaerici_, Stieda; _Lobi cerebrales_, Reissner;
Centralmasse des Geruchssinns, Carus; Hemisphaeren des grossen Hirns,
Tiedemann; Grosse Hemisphaeren, Schiess; Prosencephalon, Huxley). The
olfactory lobes (_Tubercula olfactoria_, Stieda; _Lobi olfactorii_,
Reissner; Riechkolben, Schiess; Rhinencephalon, Huxley).
α. *External form* (Figs. 98, 102, 103 _Hc_ and _L.ol_). The two
cerebral hemispheres form together the largest section of the brain;
from above they are seen to be separated by a dorsal longitudinal
fissure, which is here well marked: each hemisphere is an ovoid
body with the smaller end directed forwards and continuous with the
corresponding olfactory lobe; the posterior end forms one half of the
anterior boundary of the thalamencephalon. The olfactory lobes are two
elongated, rounded bodies directly continuous with the corresponding
cerebral hemispheres, and likewise partially separated in the median
line by a dorsal longitudinal fissure: at the point of union of the
cerebral hemispheres and olfactory lobes is a faintly marked transverse
depression.
[Illustration: Fig. 106.
Section through the lower division of the pituitary body (magnified 360
times); from Stieda.
_a_ Tubes lined with epithelium.
_b_ Blood-vessels.
]
On the ventral surface the parts are again marked off from one another
by a corresponding ventral longitudinal fissure and a transverse
groove; the two longitudinal fissures being continuous, anteriorly,
between the olfactory lobes. The cerebral hemispheres appear to be
more widely separated behind (Fig. 102) than is the case on the dorsal
surface, and in the space so formed is the _lamina terminalis_ (_Lt_).
Seen from the side, the slight depression of the upper surface, between
the cerebral hemispheres and the olfactory lobes, is seen to be
continued downwards and slightly backwards to join the corresponding
groove on the inferior surface.
The longitudinal fissures are shallow and do not meet, except at one
point, at about the middle of the cerebral hemispheres (Fig. 105). The
olfactory bulbs arise superficially (Figs. 102, 103 _I_′ and _L.ol_)
from the whole length of the olfactory lobe, between the anterior
extremity (_I_′) and the posterior (_L.ol_), where they are also
attached to the cerebral hemispheres.
β. *Internal structure.* The cerebral hemispheres and olfactory lobes
are hollow, the common cavity of each side being known as the lateral
ventricle (_Ventriculus lateralis_); these ventricles communicate
with each other, and with the third ventricle (Fig. 105). The narrow
aperture by which the lateral ventricles communicate is known as the
*Foramen of Monro* _(MF_); it communicates with the third ventricle
posteriorly, and with the space between the cerebral hemispheres
anteriorly, and thus forms a common cavity (_Ventriculus communis
loborum hemisphaericorum_, Stieda).
In general terms, each ventricle may be said to be a semilunar cavity,
prolonged backwards and forwards (Fig. 107 _c_); the outer wall is
always more or less concave, while the inner varies according to
the part of the hemisphere examined. At the anterior and posterior
extremities the inner wall is convex and bulges into the cavity
(Fig. 107); in the middle portion of the cavity the inner wall
presents a longitudinal groove (_Ventriculi lateralis cornu internum_,
Reissner), (Fig. 108 _d_), and consequently the inner wall has here two
rounded masses, an upper and a lower (_Corpus striatum_, Wiedersheim),
projecting into it. By tracing them backwards and forwards, the lower
swelling is seen to increase at the expense of the upper, while at the
same time the lateral grooves disappear; the outline of the cavity
shown in Fig. 107 is then obtained. The roof of the ventricle is arched
and broader than the floor, which, in the middle part, exists only as
a vertical slit (Fig. 108), (_Ventriculi lateralis cornu inferius_,
Reissner): towards the anterior and posterior extremities it widens and
becomes shallower (Fig. 107).
[Illustration: Fig. 107.
Transverse section through the hinder portion of the cerebral
hemispheres; from Stieda.
_c_ Lateral ventricle.
_c_′ Common ventricle of Stieda.
_d_ Longitudinal fibres.
_f_ Anterior prolongation of the third ventricle.
]
The cerebral hemispheres and olfactory lobes are composed of a fine
granular matrix, enclosing spindle-shaped, rounded, or pear-shaped
nerve cells and nuclei, and containing very fine fibres. The cells
(Fig. 109 _b_) are more numerous towards the ventricle, and somewhat
sparse towards the superficial surface. The cells are of two chief
sizes, the smaller and more numerous average 0.004 mm. to 0.008 mm. in
diameter; they are found chiefly in the deeper portions of the section,
but also form a very thin irregular layer beneath the _pia mater_: the
larger cells have an average diameter of 0.010 mm. to 0.012 mm., and
are placed towards the periphery, especially in the dorsal part of the
inner wall.
[Illustration: Fig. 108.
Transverse section near the middle of the cerebral hemispheres.
_c_ Lateral ventricle.
_d_ Groove on the inner wall.
]
In this irregular collection of cells the following centres have been
described: (1) The nucleus, through which the _corpus callosum_ passes
(Köppen); (2) the lower internal or median cell-area (Osborne),
situated above the foregoing nucleus in the posterior and middle
portions of the hemispheres; (3) the upper internal cell-area (Osborne)
is the area of large cells in the dorsal part of the inner wall; (4)
the _Corpus striatum_ (Osborne) is a mass of cells between the _corpus
callosum_ and the _commissura anterior_; Köppen doubts the correctness
of Osborne’s opinion, and suggests that a group of cells found in the
wall of the third ventricle in front of ‘Meynert’s band’ may perhaps be
a _corpus striatum_.
[Illustration: Fig. 109.
From a transverse section through one of the cerebral hemispheres; from
Stieda. (Magnified 360 times.)
_a_ Epithelium of lateral ventricle.
_b_ Nerve cells.
_c_ Connective-tissue processes from the Pia mater.
]
A bundle of longitudinal medullated nerve-fibres, the ‘round bundle,’
is found on either side of the median line (Fig. 107 _d_), and near
the lower border in the posterior portion of this region; these fibres
can be traced from the posterior section of the thalamencephalon; they
diminish in number as they course through the base of the cerebral
hemispheres, and are ultimately lost in the lower anterior part of the
outer walls. A second strand of longitudinal fibres is the continuation
of that of the _Tuber-cinereum_ above described, which can be followed
to the outer wall of the posterior part of the ventricles, and to the
anterior commissure.
The commissures are: (1) The _corpus callosum_, a large bundle of
transverse fibres, seen best in a transverse section, at the point of
junction between the _lamina terminalis_ and the cerebral hemispheres,
forming an arch over the roof of the anterior prolongation of the third
ventricle. The fibres course to the inner and anterior parts of the
hemispheres, and are situated chiefly behind the _foramen Monroi_.
To this commissure must be added those fibres which unite the two
olfactory lobes, and possibly the fibres (_Commissura posterior_)
found in the roof of the third ventricle (Köppen). (2) The _Commissura
anterior_ (Stieda), a smaller set, found immediately under the floor
of the common ventricle, forming in their course outwards a curve,
with the concavity directed downwards. This commissure connects the
‘round bundles’ of opposite sides, and those fibres coursing with the
‘round bundles’ to the olfactory lobes constitute the _pars olfactoria_
of the _commissura anterior_. To this commissure must also be added
some fibres found on the ventral surface of the _commissura anterior_
and connecting the two strands of the _Tuber-cinereum_; an unusually
coarse strand of these fibres can be traced to the inner wall of the
ventricle, and is termed the _pars olfactoria interna_ by Osborne.
The general structure of the olfactory lobes resembles that of the
hemispheres; the olfactory nerves arise each by two roots, an outer
and inner. The outer root arises from the outer wall near the groove
between the corresponding hemisphere and olfactory lobe; the inner or
anterior root arises from the anterior surface of the olfactory lobe.
Both roots have a peculiar method of origin from the extremely fine
fibrillar network of the matrix (Nerve-fibre-conglomerate, Köppen), in
which are rounded dark bodies known as ‘glomeruli;’ in the ‘glomeruli’
dark points and nuclei are seen, between larger and smaller bands of
nerve-fibres. Köppen holds that all the sensory nerves of the brain
arise in a similar manner.
A decussation takes place between the two inner roots of the olfactory
nerves; possibly the external roots are connected by means of the
_commissura anterior_.
Very little *pigment* exists in the cerebral hemispheres or olfactory
lobes, the greater portion is found in the upper part of the inner
walls of the cerebral hemispheres.
The *epithelium* of the *ventricles of the brain*, like that of the
central canal of the *spinal cord*, consists of conical cells with
their bases directed towards the cavity, and their apices directed
peripherally and prolonged into distinct processes (Figs. 104, 109
_a_). In such situations, as the choroid plexuses, where nervous
tissue is absent and the cavity is completed by _pia mater_ alone, the
epithelial cells are flattened. Everywhere else it is ciliated[55]
and possesses distinct round nuclei which are as broad as the cells
themselves. The epithelium is somewhat irregularly and sparsely
pigmented; the ventral parts of the central canal of the spinal cord,
of the fourth ventricle, and of the Sylvian aqueduct are always more
pigmented than the dorsal parts.
[Footnote 55: Schmidt (_l. c._) states that the epithelium of the
central canal of the spinal cord is not ciliated.]
PLAN OF THE ARRANGEMENT OF THE NERVE-FIBRES OF THE CENTRAL NERVOUS
SYSTEM, ACCORDING TO KÖPPEN.
NERVE FIBRE NERVE-FIBRE COMMISSURES. NERVE-FIBRES
STRANDS IN STRANDS IN WHICH CONNECT
THE WHITE THE GREY THE STRANDS OF
MATTER. MATTER. WHITE FIBRES.
{1. The ventral 1. Longitudinal 1. The ventral
{ columns, fibres in commissure.
{ including the dorsal 2. The dorsal
{ the strand portion of commissure
{ of coarse the grey (rudimentary).
The { fibres. matter.
spinal {2. The lateral
cord. { columns.
{3. The dorsal,
{ columns
{ including
{ Goll’s
{ column.
{1. The ventral 1. Longitudinal 1. The ventral 1. The fibrae
{ columns, fibres of the commissure: arcuatae.
{ including Substantia _a._ Dorsal
{ the strand gelatinosa portion.
{ of coarse Rolandi, and _b._ Ventral
{ fibres which give portion.
{ dorsal off ascending 2. (The dorsal
{ longitudinal vagal and commissure
{ strand. trigeminal is wanting.)
{2. The lateral roots.
{ columns,
The { which give
medulla { off an as-
oblongata.{ cending
{ (recurrent)
{ vagus-root.
{3. The dorsal
{ columns.
{ _a._ Ascending
{ trigeminal
{ root.
{ _b._ Auditory
{ root.
{ _c._ Descending
{ auditory
{ root.
{1. The ventral 1. Longitudinal 1. The ventral 1. The fibrae
{ columns, fibres of the commissure. arcuatae.
{ including grey matter. 2. The dorsal
{ the dorsal Small ascend- commissure,
{ longitudinal ing trigeminal cerebellar
{ strand (the root. commissure
{ strand of and trochlear
{ coarse fibres decussation.
The { has dis-
cere- { appeared).
bellum {2. The lateral
and the { columns (each
pars { receives a
commis- { strand from
suralis. { the cere-
{ bellum).
{3. The dorsal
{ columns.
{ _a._ Large as-
{ cending tri-
{ geminal root.
{ _b._ Descending
{ auditory
{ root.
{1. The ventral (Wanting.) 1. The ventral 1. The fibrae
{ columns, commissure. arcuatae.
{ including the 2. The dorsal
{ dorsal longi- commissure.
{ tudinal _a._ Commissura
{ strand. posterior.
{2. (The lateral _b._ Marginal
The { columns can- commissure.
optic { not now be
lobes. { distinguished
{ from the ven-
{ tral columns.)
{3. The dorsal
{ columns: two
{ ascending
{ opticus-roots.
{1. The ventral (Wanting.) 1. The ventral 1. The fibrae
{ and dorsal commissure: arcuatae.
The { columns. _a._ Commissura
thalam- { _a._ Fibres from transversa
enceph- { the optic Halleri.
alon and { lobes. _b._ Commissura
the cere- { _b._ The ‘round anterior.
bral hemi-{ bundle.’ 2. The dorsal
spheres. { _c._ The ‘Thal- commissure,
{ amus-Tuber- the corpus
{ cinereum callosum.
{ strand.’
C. THE COVERINGS OF THE BRAIN AND SPINAL CORD.
1. The _Pia mater_ closely invests the whole of the brain and spinal
cord; it may, in fact, be regarded as the flattened, outermost layer
of the connective-tissue material which supports the nervous elements;
fine processes (Fig. 109 _c_) pass radially from its inner surface to
join the general connective-tissue matrix or neuroglia. It is usually
pigmented, those portions covering the optic lobes and spinal cord
being especially deeply pigmented: on the cerebral hemispheres it
contains very little pigment; at times, indeed, in _R. temporaria_,
pigment is absent from this part.
The _pia mater_ is continued on to the choroid plexuses and pituitary
body, and on to the pineal body by means of the pedicle; the membrane
is very vascular, and forms, especially for the cerebral hemispheres
and the olfactory lobes, a very important source for the direct supply
of blood-vessels.
2. The _Dura mater_, or lining membrane of the cranial cavity and
vertebral canal, is a connective-tissue membrane containing many
very much branched, pigmented cells. This membrane is not so deeply
pigmented as the _pia mater_, except in that portion covering the
cerebral hemispheres and the olfactory lobes, which is much darker than
the corresponding portion of the _pia mater_.
3. The *arachnoid membrane* is the layer of endothelial cells covering
the inner surface of the _dura mater_: by means of the blood-vessels
and nerves, etc., it is continued on to the _pia mater_ of the spinal
cord and brain, which it in like manner closely invests. Masses
of *calcareous crystals* are found between the epineurium and the
arachnoid (Wiedersheim) on each spinal nerve at its exit from the
intervertebral foramen, also on the trigeminal nerves in the cranium.
Additional smaller and more irregular masses are found on the dorsal
part of the _dura mater_ of the spinal cord.
D. THE VESSELS OF THE BRAIN AND SPINAL CORD. (Fig. 110.)
The arteries of these organs are derived from the internal carotids and
the _arteriae vertebrales_. As soon as the internal carotid arteries
reach the cranial cavity each divides into two branches, an anterior
(_Ramus anterior_, Schöbl[56]) and a posterior (_Ramus posterior_,
Schöbl); the anterior branches course forwards on the lower part
of the surface of the brain as far as the anterior portion of the
thalamencephalon, where they again divide; one division, _arteria lobi
hemisphaerici inferior externa_ (Schöbl), continues forwards along the
outer surface of the cerebral hemisphere and of the olfactory lobe
as far as the olfactory bulb, where it may still be distinctly seen;
it gives off branches to the adjacent parts in its course forwards.
The vessels of the two sides communicate with each other by means of
delicate transverse vessels (_Arteriae communicantes anteriores_).
The second division, _arteria lobi hemisphaerici superior interna_
(Schöbl), of the _ramus anterior_ courses on the thalamencephalon to
the dorsal surface, gives a large branch to the choroid plexus of the
fourth ventricle, and runs forwards in the dorsal longitudinal fissure;
it supplies vessels to all the neighbouring parts.
[Footnote 56: These names are those adopted by Schöbl for corresponding
vessels in the newt, the translator has accepted them as being
suitable, with slight modification, to the vessels of the frog.]
The _rami posteriores_ converge as they course backwards, and
ultimately unite to form an _arteria basilaris_, which is continued in
the median line of the under surface of the spinal cord as the _arteria
spinalis anterior_. The _ramus posterior_ gives off, in its course,
many small vessels to the neighbouring parts, and two larger vessels
on either side, one of which, the _arteria lobi optici_ (Schöbl), is
distributed to the optic lobes, while the other passes to the pituitary
body.
The branches of these vessels form a network in the _pia mater_, from
which the nervous tissue is supplied; they also send numerous branches
directly into the brain and cord, and these have a similar arrangement
for all parts of the brain with the exception of the cerebral
hemispheres and olfactory lobes; more or less vertical branches arise
from the posterior parts of the upper borders of the _rami anteriores_,
from the whole of the _rami posteriores_, and from the _arteria
basilaris_; these course upwards from their place of origin into the
corresponding part of the brain, give off a few branches in the white
matter, and then branch freely, and at somewhat sharp angles, in the
grey matter. In the _pars commissuralis_ a large branch may be traced
from the _ramus posterior_ on either side upwards into the cerebellum
almost to its upper border. The vessels of the cerebral hemispheres
and olfactory lobes seem to possess no other definite arrangement than
that described above. The grey matter seems, on the whole, to be more
vascular than the white; the vessels of the latter are chiefly arranged
radially to the surface, and run in courses which are more or less
straight; the vessels of the grey matter are more irregular and sinuous.
The _Arteria spinalis anterior_ courses along the whole length of the
spinal cord, giving off lateral branches and communicating with _rami
spinales_ (branches of the _Arteria vertebralis_). These branches form
a plexus in the _pia mater_, from which vessels pass at irregular
points into the cord; one set of small vessels, described by Reissner,
pass in a straight course from the superior longitudinal sinus towards
the _substantia reticularis_, where they divide. Other branches pass
directly from the _arteria spinalis anterior_, through the ventral
longitudinal fissure, and there divide; the twigs as a rule avoiding
the _septum medium_ and passing in greater part towards the ventral
horns. The vessels in the white matter are for the most part radial and
straight, while in the more vascular grey matter they are irregular and
more sinuous in their course.
[Illustration: Fig. 110.
Diagram to show the _Vena spinalis posterior_, the _Venae spinales
superiores_, and the origin of the _Vena jugularis interna_.
_H_ Hemispheres.
_ji_ Internal jugular.
_op_ Optic lobes.
_mo_ Medulla oblongata.
_spp_ Vena spinalis posterior.
]
The choroid plexus of the third ventricle (_Plexus choroideus
ventriculi tertii_, Reissner) lies, as already described, on the roof
of the third ventricle; it is somewhat triangular in form (_Plexus
venosus triangularis_, Schöbl), and is evidently a prolongation of
the _pia mater_, with an increased supply of vessels. It receives,
at its anterior angle, veins from the cerebral hemispheres and the
adjacent parts. The under surface is covered with a layer of ciliated
pavement epithelium. At the posterior angles of the plexus the veins
communicate on either side (Fig. 110) with the anterior lateral
prolongation of the _vena spinalis superior_, and with the internal
jugular vein. The small body usually named the pineal body, and placed
on the roof of the ventricle, is only a small thickened portion of
the plexus, and consists of a group of convoluted blood-vessels. This
plexus sends a considerable bunch of vessels into the upper part of the
third ventricle. The choroid plexus of the fourth ventricle (_Plexus
choroideus ventriculi quarti_, Reissner) is a triangular membrane,
slightly attached to the borders of the fourth ventricle. Its upper
surface is flat and bounded at either side by a large vein, the _vena
spinalis superior_; anteriorly it is bounded by the _cerebellum_.
The under surface is not flat; in the middle line is a slight furrow
corresponding to the position of a median vessel, which may, when
injected, be seen from the dorsal surface; from it a number of short
vessels pass outwards and slightly backwards to the outer border. The
connective-tissue between these vessels is pushed down into the cavity;
in this manner one obtains a double row of flattened villous-looking
bodies, which frequently have their tips pigmented. The under surface
of the plexus is clothed with flattened, ciliated epithelium.
On either side of the pituitary body is another small venous plexus
(_Plexus lateralis_, Schöbl); it communicates above with the posterior
angle of the choroid plexus of the third ventricle; externally, with
the internal jugular vein; and internally with its fellow of the
opposite side by more or less irregular transverse vessels, which,
together with a median vein from the fissure between the cerebral
hemispheres, form an irregular _circulus venosus_ around the pituitary
body. These plexuses receive blood from the lower part of the cerebral
hemispheres, the thalamencephalon, the optic lobes, and from the
pituitary body. The veins of the spinal cord open into the dorsal,
_vena spinalis posterior_ (Fig. 110 _spp_), which bifurcates at the
posterior angle of the fourth ventricle, one division passing to either
side and forming, as already described, the outer border of the choroid
plexus; anteriorly it opens into the internal jugular vein (Fig. 110
_ji_).
The blood-vessels, both arteries and veins, are irregularly pigmented,
both on the surface and in the interior of the central nervous system;
those of the cerebral hemispheres and olfactory lobes have very little
or no pigment.
DESCRIPTION OF THE FIGURES ON PLATE I.
Fig. 111. Dorsal view of the orbit, etc.; deep dissection.
_c_ Course of the palatine nerve.
_db_ Fibrous plate.
_dm_ M. depressor maxillae.
_ef_ Terminal branches of the ophthalmic nerve.
_F_ Facial with R. anterior of the glossopharyngeal.
_g,g,g_ Terminal twigs of the ophthalmic nerve.
_h_ Muscular twigs of the Ram. maxillaris.
_ics_ M. intertransversar. capitis superior.
_ii_ Twigs of upper eyelid.
_K_ Terminal twigs of the Ram. maxillaris.
_la_ M. levator anguli scapulae.
_pt_ M. pterygoideus.
_sc_ M. sterno-cleido-mastoideus.
_Sp_ Sympathetic nerve.
_t_ M. temporalis.
_tr_ Nasal branch.
Union of facial nerve with Ram. anterior of the glossopharyngeal
nerve.
_I_ Olfactory nerve.
_II_ Optic nerve.
_III_ Motor oculi nerve.
_IV_ Trochlear nerve.
_Vb_ R. palatinus }
_Vc_ R. maxillo-mandibularis } of the trigeminal
_Vc_′ R. maxillaris } nerve.
_Vd_ R. mandibularis }
_Ve(VII)_ Facial nerve.
_Vg_ Gasserian ganglion.
_VN_ Trigeminus.
_VS_ Sympathetic nerve.
_VI_ Abducens nerve.
_VII_′ Facial nerve.
_VIII_ Auditory nerve.
_X1_ Ram. anterior of the glossopharyngeal.
_X2_ Glossopharyngeal nerve.
_X3_ Pneumogastric nerve.
_XG_ Ganglion nervi vagi.
_XI_ Accessory nerve.
Fig. 112. Dorsal view of the orbit, etc.; superficial dissection.
_e_ External branch of the ophthalmic nerve.
_f_ Internal branch of the ophthalmic nerve.
_g,g,g_ Terminal twigs of the ophthalmic nerve.
_II_ Optic nerve.
_III_ Motor oculi nerve.
_IV_ Trochlear nerve.
_Va_ Ophthalmic nerve.
_Vc_ R. maxillo-mandibularis.
_Vc_′ R. maxillaris of the trigeminal nerve.
_Vd_ R. mandibularis of the trigeminal nerve.
_VI_ Abducens nerve.
_VI_′ Ciliary nerves.
Fig. 113. View of roof of mouth; mucous membrane, etc., removed.
_a_ Branch of the Ram. palatinus to the Harderian gland.
_b_ Branch of the Ram. palatinus to the intermaxillary gland.
_c_ Inosculating-branch of the Ram. palatinus.
_Ch_ Internal naris.
_d_ Cutaneous branch of the Ram. palatinus.
_db_ Fibrous plate.
_F_ Ramus mandibularis of the facial nerve.
_Gl_ Intermaxillary gland.
_HD_ Harderian gland.
_l_ Eyeball.
_m_ M. masseter.
_Ms.ob.i._ M. obliquus inferior.
_OK_ Upper jaw.
_r_ M. retractor bulbi.
_ri_ M. rectus internus.
_ri_′ M. rectus inferior.
_sc_ M. sterno-cleido-mastoideus.
_uk_ Mandible.
† Terminal branch of Ram. palatinus.
* Union of facial nerve with Ram. anterior of the
glossopharyngeal.
_III_ Motor oculi nerve.
_Vb_ Ramus palatinus of trigeminal nerve.
_Vc_ Ramus maxillo-mandibularis of the trigeminal nerve.
_Vc_′ Ramus maxillaris of the trigeminal nerve.
_Vd_ R. mandibularis.
_Ve(VII)_ Facial nerve.
_X_ Pneumogastric nerve.
_X1_ Glossopharyngeal nerve.
Fig. 114[57]. Lateral dissection of head, etc., to show the cranial
nerves, etc.
[Footnote 57: The branches of the vagus which are represented in this
figure as crossing the petrohyoid muscles ought to be underneath
them.--_Trans._]
_c_ Cardiac nerve.
_F_ Union of facial and Ram. anterior of the
glossopharyngeal nerve.
_h_ Ram. hyoideus of the glossopharyngeal nerve.
_la_ M. levator angi scapulae.
_lgd_ M. longissimus dorsi.
_m_ M. masseter.
_mt_ Ram. mandibularis of the glossopharyngeal nerve.
_M1_ Hypoglossal nerve.
_M2_ Brachial nerve.
_Oh_ Anterior cornu of the hyoid bone.
_oi_ M. obliquus internus.
_ph1_ M. petrohyoideus I.
_ph2_ M. petrohyoideus II.
_ph3_ M. petrohyoideus III.
_ph4_ M. petrohyoideus IV.
_pp_ Pharyngeal branches of the pneumogastric nerve.
_tt_′ M. temporalis.
_us_ Muscular twigs of the Ram. mandibularis of the
trigeminal nerve.
_Z_ Tongue.
_Va_ Terminal twigs of the ophthalmic nerve.
_Vc_ Ram. maxillaris of the trigeminal nerve.
_Vd_ Ram. mandibularis of the trigeminal nerve.
_Ve(VII)_ Facial nerve.
_X1_ Ram. anterior of the glossopharyngeal nerve.
_X2_ Glossopharyngeal nerve.
_X3_ Pneumogastric nerve.
_X3g_ Ram. gastrici of the pneumogastric nerve.
_X3l_ Ram. laryngeus.
_X3p_ Ram. pulmonales of the pneumogastric nerve.
_XI_ Accessory nerve of the pneumogastric nerve.
Fig. 115. Dissection of the floor of the mouth.
_dm_ M. depressor maxillae.
_F_ United facial nerve and Ram. anterior of the
glossopharyngeal nerve.
_gh_ } M. geniohyoideus.
_gh_′ }
_h_ Ram. hyoideus of the glossopharyngeal nerve.
_H_ Heart.
_Lg_ Lung.
_m_′ Ram. mandibularis of the glossopharyngeal nerve.
_M1_ Hypoglossal nerve.
_M2_ Brachial nerve.
_Oh_ Anterior cornu of the hyoid bone.
_oh_ Momohyoideus.
_ph1_ M. petrohyoideus I.
_ph2_ M. petrohyoideus II.
_ph3_ M. petrohyoideus III.
_ph4_ M. petrohyoideus IV.
_sc_ M. sterno-cleido-mastoideus.
_sh_ M. sterno-hyoideus.
_sm_ M. mylohyoideus (submaxillaris).
_smt_ M. submentalis.
_TT_ Thyroid.
_uk_ Mandible.
_us_ Muscular twigs of the Ram. mandibularis.
_X2_ Glossopharyngeal nerve.
_X3_ Pneumogastric nerve.
_X3c_ Rami cardiaci of pneumogastric nerve.
_X3l_ Ram. laryngeus of the pneumogastric nerve.
_X3p_ Ram. pulmonalis of the pneumogastric nerve.
II. THE PERIPHERAL NERVOUS SYSTEM.
E. THE CRANIAL NERVES.
(To facilitate reference the original arrangement of this part has been
altered.)
[There are ten pairs of cranial nerves in the frog, which are numbered
in order from before backwards. The mode of origin of these nerves, and
their deeper relations with the respective parts of the brain to which
they belong, have already been described.]
*1.* The *olfactory nerve* (_N. olfactorius_), [(Figs. 97, 98, 102,
103, 111 _I_) runs a very short course only a few lines in length,
and escapes from the cranium by an opening in the cartilage of the
sphenethmoid into the nasal cavity, where it divides into two branches,
each of which breaks up into a brush of filaments, to be distributed
in the olfactory mucous membrane. The nerve contains no white fibres].
(See organ of smell, p. 385.)
*2.* The *optic nerve* (_N. opticus_), (Figs. 97, 102, 103, 111 _II_)
[arises, as already described, by the optic tract, and joins with its
fellow at the optic chiasma or commissure, where part of the fibres
pass over to the opposite side (according to Michel all the fibres
cross). Each optic nerve then courses outwards, piercing the cartilage
of the cranium and so reaching the eyeball]. (See organ of sight,
p. 408.)
*3.* The *motor oculi* (_N. oculomotorius_, _Oculo-motor_, _Motor
communis_), (Figs. 102, 111, 112, 113 _III_). From its origin it
courses outwards and forwards, perforating with a slight obliquity
the cartilaginous wall of the cranium, just in front of the Gasserian
ganglion (Fig. 116 _III_); on reaching the orbit it divides into two
branches, between the _Levator bulbi_ and the _Rectus internus_ and
_inferior_. One branch, _Ramus superior_, runs over and parallel to
the _Ramos ophthalmicus Trig._ and enters the under surface of the
_Rectus superior_; the second, lower branch, _Ramus inferior_, supplies
filaments to the _Rectus internus_ and _inferior_ and to the _Obliquus
inferior_. Apparently it exchanges fibres with the ophthalmic division
of the trigeminal nerve.
[That portion of the motor-oculi between its branch to the _Rectus
superior_ and to that to the _Rectus internus_ contains a number of
nerve cells; according to Schwalbe (_l. c._, p. 235 and Pt. XII,
Fig. 4) these cells are arranged in four groups or ganglia; the second
group forms a very slight prominence, and is covered by a very fine
layer of nerve fibres, it also gives off some extremely fine nerves to
the eyeball; this is perhaps a ciliary ganglion (_Ganglion ciliare_,
Schwalbe). Beard, however, names it ‘mesocephalic ganglion.’ The other
three groups are simply clusters of cells between the fibres of the
nerve.]
*4.* The *pathetic* or *trochlear nerve* (_N. trochlearis_,
_patheticus_), (Figs. 102, 103, and 112 _IV_). From its origin it
courses forwards with and then crosses the motor-oculi; it perforates
very obliquely the cartilaginous lateral wall of the cranium, in
front of the motor oculi but above and very slightly behind the optic
foramen (Fig. 116); it runs parallel to and in company with the _Ramus
opthalmicus trigemini_, and appears to exchange a few fibres with it,
which, however, according to de Watteville, Stannius, Cuvier, and
Wyman, is not really the case. In this course it lies first to the
inner, then to the outer side of the ophthalmic, over which it passes
to supply the _Rectus superior_. [The pathetic and ophthalmic nerves
are sometimes enclosed in a common sheath (de Watteville).]
*5.* The *trigeminal nerve* (_N. trigeminus_), (Figs. 97, 102, 103,
111, 112, 113, and 114 _V_) is the largest of the cranial nerves in
the frog; from its origin it runs outwards and forwards to the skull
wall, and just before reaching this enters the large _Gasserian
ganglion_. It then passes through the cranial wall immediately in
front of the auditory capsule, and divides at once into two main
branches (Fig. 111 _Vg_, etc.), the _Ramus ophthalmicus_ and the _Ramus
maxillo-mandibularis_.
The Gasserian ganglion is a large, yellow, oval ganglion placed in
a depression in the outer wall of the cranium; it is covered by a
‘periganglionic gland,’ which is similar in structure to that of
a spinal ‘periganglionic’ gland (see p. 180), the fibrous capsule
being stronger. This ganglion receives three other nerves besides the
trigeminal, _viz._ the sixth and seventh nerves, and branches of the
sympathetic.
According to de Watteville, these nerves are arranged on the lower
surface of the ganglion, so that the sympathetic is below, the
sixth above it, then the seventh, while the fifth is uppermost;
the sympathetic splits into several bundles which join the various
branches of the ganglion; the sixth divides into two bundles, one of
which usually joins the ophthalmic, while the other makes its exit
independently; the seventh splits into two bundles, one of which
leaves the ganglion as the hyomandibular branch, the other gives some
fibres to the palatine branch of the trigeminal nerve, and is then
continued as the palatine branch of the facial.]
*a.* The _Ramus ophthalmicus_ (_Ramus nasalis_, Fischer; Ophthalmic
or Orbital Branch, Wyman; Orbito-nasal or Ophthalmic Nerve, de
Watteville), (Figs. 111 and 112 _Va_). After leaving the Gasserian
ganglion the nerve is directed forwards parallel to the side of the
cranium, between this and the eyeball. It lies beneath the _Rectus
superior_, but above all the other muscles of the eyeball and the optic
nerve. At the anterior end of the orbit it divides into two branches
(_e_ and _f_) which pass through apertures (_Foramen pro ramo nasali_)
in the cartilage of the sphenethmoid, to reach the nasal cavity, where
they lie between the cartilage and mucous membrane. In this position
the nerves supply branches to the mucous membrane and then pierce the
skull to appear on the surface (Figs. 111, 112 _g,g,g_, 114 _Va_), the
skin of which they supply. The branches inosculate with each other and
communicate with the anterior twigs of the _Ramus maxillaris_ (Fig. 114
_Vc_) and with those of the _Ramus palatinus_ (Fig. 113 _Vb_).
In its course through the orbit the _Ramus ophthalmicus_ gives off:--
(1) Near the Gasserian ganglion one, two, or three small branches,
which communicate with the trochlear nerve, and may then be traced to
the sclerotic of the eyeball; some of the twigs enter near the optic
nerve, others nearer the cornea. They are regarded as _Ciliary nerves_
(_Nervi ciliares_).
(2) A large branch, the *palatine nerve* (_Ramus palatinus_),
(Figs. 111 and 113 _Vb_, _b_). This nerve, after receiving the palatine
branch of the facial, descends on the inner border of the _Levator
bulbi_ to the mucous membrane of the mouth, to which it gives numerous
filaments; it then runs parallel and near to the median line, lying on
the base of the skull; and near the front of the orbit it divides into
three branches. The smallest (_a_) supplies the Harderian gland (_HD_);
the second (_b_) continues in the course of the original nerve, pierces
the vomer, and divides, giving filaments to the mucous membrane in its
whole course, while the terminal twigs supply the intermaxillary gland
(_Gl_) and the surrounding structures. One of these (†) ascends on the
anterior border of the sphenethmoid to the intermaxillary (internasal,
Born) space to supply the numerous glands and to inosculate by one or
two twigs with the nasal branch (_tr_) of the trigeminal. The third
branch of the palatine nerve (_c_) curves directly outwards, just
behind the palatine bone, to the inner surface of the maxillary bone;
it then courses backwards, pierces the fibrous plate (_db_) between the
eyeball and the pterygoid bone, and ultimately unites with superior
maxillary division of the trigeminal nerve (_Vc_′). Just before
piercing the fibrous plate it gives off a tolerably large nerve (_d_)
to the mucous membrane, and in its whole course it gives off twigs to
the mucous membrane and surrounding structures; many of these twigs
inosculate with other terminal twigs of the trigeminal.
[This nerve has been minutely described by Stirling and Macdonald;
these observers find that the branches form a very fine and
close plexus in the mucous membrane, etc.; fibres were traced to
blood-vessels, glands, etc., and ganglion cells were found scattered
along the nerves. The fibres are both medullated and non-medullated,
and many of the cells are described as ‘spiral cells’ (see page 201)
such as those described by Arnold in the sympathetic system of the
frog.]
*b.* The _Ramus maxillo-mandibularis_ (_Ramus maxillaris_, Ecker and
Hoffmann; Supra-maxillary, Humphry; Upper Maxillary Branch, Wyman),
(Figs. 111, 112, and 113 _Vc_). This nerve is the largest division
of the trigeminal; it runs directly outwards behind the eyeball, in
front of the auditory capsule, and between the temporal and pterygoid
muscles. After a very short course it divides into the maxillary and
mandibular nerves. The nerve gives off before its division a few fine
filaments (_i,i_) to the hinder half of the upper eyelid and to the
surrounding skin, also a branch (_h_) [not correctly drawn in Fig. 111]
which divides to supply twigs to the temporal and pterygoid muscles.
(1) The _Ramus maxillaris_ (_Ramus supramaxillaris_, Ecker; _Ramus
maxillaris superior_, Hoffmann; Upper Maxillary Branch, Wyman;
Supramaxillary, Humphry and de Watteville), (Figs. 111, 112, 113, and
114 _Vc_) runs outwards and then forwards, between the eyeball and
the outer wall of the orbit, to the margin of the upper jaw (_K_); a
large portion terminates in a number of small branches for the supply
of the skin of the lower eyelid, the upper lip, and of the parts
between the tympanic membrane and the external nares. Some of these
twigs inosculate with twigs of the palatine and ophthalmic nerves. The
second portion of the nerve unites with the palatine nerve, as already
described.
(2) The _Ramus mandibularis_ (_Ramus maxillaris inferior_, Hoffmann;
Mandibular or Lower Jaw Branch, Wyman; Inframaxillary, Humphry and de
Watteville), (Figs. 111, 112, 113, 114, and 115 _Vd_, _us_). As far as
the outer margin of the eyeball, this nerve runs parallel to and behind
the _Ramus maxillaris_, in which course it supplies branches to the
temporal and pterygoid muscles; it then curves backwards, outwards, and
downwards to the under surface of the squamosal bone, where it supplies
a twig to the _Depressor maxillae_, and then perforates the _Masseter_:
in this manner it reaches the outer surface of the mandible, just
behind the insertion of the temporal muscle; it then courses forwards,
under the skin, to the _Symphysis menti_. In this course the nerve
gives off numerous branches to the skin and surrounding parts, it also
supplies the mylo-hyoid and submental muscles; one branch (Figs. 114
and 115 _us_) is larger than the rest, and supplies the under surface
of the floor of the mouth and lower lip.
*6.* The *abducens nerve* (_Nervus abducens_, Ecker and Hoffmann;
included in the trigeminal, Wyman), (Figs. 111 and 112 _VI_). This very
slender nerve courses along the inner wall of the cranium from its
origin to the Gasserian ganglion (_q.v._) which it joins, and leaves
this in contact with the ophthalmic division of the trigeminal nerve:
the nerve then bifurcates in the orbit; the outer branch supplies
the _Rectus externus_, the inner inosculates with small twigs of the
ophthalmic division of the trigeminal, and then gives off a number of
small ciliary nerves, already described, and one special branch to the
_Retractor bulbi_.
*7.* The *facial nerve* (_N. facialis_, Ecker and Hoffmann; _Facialis_
(_Portio dura_), Wyman; Facial or Jugular Nerve, Stannius), (Figs. 111,
113, and 114 _Ve_ _VII_) arises immediately behind the trigeminal, and
runs forwards, first in company with the auditory nerve, then alone, to
the Gasserian ganglion (_q.v._), with which it unites; it again appears
at the posterior angle of the ganglion, and escapes from the cranium in
company with, and immediately behind, the _Ramus mandibularis_ of the
trigeminal, and divides at once into two branches.
*a.* The _Ramus palatinus_ at once unites with the palatine branch of
the ophthalmic division of the trigeminal nerve. Wiedersheim doubts
this arrangement, and holds that the two portions arise in common
from the Gasserian ganglion; neither has Wyman (_Rana pipiens_)
described this branch of the facial. [De Watteville states that the
_Ramus palatinus_ and the palatine branch of the ophthalmic nerve
are separated by the carotid artery. In urodeles the two nerves are
distinct.]
*b.* The _Ramus hyomandibularis_ (_Ramus jugularis_, Hoffmann;
Facial Nerve, Wyman), (Figs. 113 and 114, _Ve_ _VII_). The nerve is
directed outwards and backwards so as to pass around the bony wall
of the auditory capsule, it then crosses over the inner end of the
columella, with which it is in close contact, and is then joined, under
cover of the _sterno-cleido-mastoideus_ (_sc_), by a branch (_Ramus
communicans_) of the glossopharyngeal (see Fig. 111 *). The single
trunk (_F_) so formed is directed downwards in the posterior wall of
the Eustachian tube to just above the angle of the mandible, where it
divides into three branches, or sometimes into two, in which case a
third nerve is supplied by one of the others, usually by the _Ramus
hyoideus_.
(1) The _Ramus mandibularis_ (_Ramus mentalis_, Hoffmann; Third Trunk
of the Facial, Wyman), (Figs. 114 _mt_ and 115 _m_′) passes inside the
angle of the jaw and courses forwards, between the skin and mylo-hyoid
muscle, parallel to the _Ramus mandibularis_ of the trigeminal nerve,
as far as the symphysis. It supplies small twigs to the neighbouring
parts of the mucous membrane of the mouth.
(2) The _Ramus hyoideus_ (_Ramus jugularis_, Hoffmann; Second Trunk of
the Facial, Wyman), (Figs. 114, 115 _h_) is the largest division of
the facial; it courses forwards subcutaneously over the _deltoideus_
and the hinder fibres of the _mylo-hyoideus_ to the anterior cornu of
the hyoid bone, supplying its muscles and the skin of the throat and
sternal region.
(3) The _Ramus auricularis_ (First Trunk of the Facial, Wyman); is a
small branch, directed outwards; it supplies a branch to the walls of
the tympanic cavity, and is finally distributed in the skin under the
tympanic membrane and behind the angle of the mouth.
*8.* The *auditory nerve* (_N. acusticus_, Ecker, Hoffmann; Auditory
Nerve, Wyman). This nerve has a very short course in the cranium;
it reaches the auditory organ by a foramen (Fig. 116 _VIII_) in the
auditory capsule, and is then distributed in the ear, with which it
will be described.
*9.* The *glossopharyngeal nerve* (_N. glossopharyngeus_, Ecker;
_Ramus glosso-pharyngeus_, Hoffmann; Glossopharyngeal, Wyman;
Glossopharyngeal of the Vagus, Müller), (Figs. 102 and 103 _X_, 111,
113, 114, and 115 _X_^2) arises in common with the pneumogastric nerve,
and quits the skull with it through an opening (_Canalis nervi vagi_)
immediately behind the auditory capsule, and at once divides into two
branches; both of which lie under the _MM. intertransversarii capitis_
and are covered by the _Depressor mandibulae_.
*a.* The _Ramus anterior_ (Verbindungsast des Glossopharyngeus,
Wiedersheim; _Ramus communicans_, Hoffmann; Uniting Branch, Wyman;
Laryngeal Branch of the Vagus, Volkmann; _Communicans ad facialem_,
de Watteville), (Figs. 111, 113, and 114 _X^1_). This nerve curves
downwards and forwards around the auditory capsule and beneath the
_Depressor mandibuli_ to join the facial nerve, as already described.
*b.* The _Ramus posterior_ (_N. glossopharyngeus_, Wiedersheim; _Ramus
lingualis_, Hoffmann), (Figs. 111, 113, and 114 _X^2_). This nerve
runs downwards and forwards to the ventral surface of the pharynx,
dips underneath the _Petrohyoideus IV_, to appear again, after a short
interval, by piercing the _Petrohyoideus II_ or _III_, courses parallel
to and behind the anterior cornu of the hyoid bone, and thus reaches
the floor of the mouth. The nerve then runs forwards in a very sinuous
course, close to the median line, and between the _Geniohyoideus_
and _Hyoglossus_; in its course on the floor of the mouth it crosses
the hypoglossal nerve. It supplies the petrohyoid muscles, and gives
numerous small branches to the mucous membrane of the pharynx (_Ramus
pharyngeus_, Hoffmann).
*10.* The *pneumogastric* or *vagus nerve* (_Vagus_; _Ramus
intestinalis nervi vagi_, Fischer, Hoffmann; Vagal Trunk, Wyman;
Vaso-sympathetic, Gaskell), (Figs. 111, 113, 114, and 115 _X_^3). This
nerve arises in common with the glossopharyngeal; the two nerves leave
the skull together by an opening in the exoccipital bone (_Canalis
nervi vagi_); immediately outside the skull they acquire a ganglionic
enlargement (_Ganglion condyloideum_, _Ganglion nervi vagi_), (Fig. 111
_XG_); in this course the glossopharyngeal lies in front of the
pneumogastric, which it then leaves. The pneumogastric lies first upon
the _M. levator anguli scapulae_, then running backwards and downwards
along the hinder border of the _Petrohyoideus IV_ it comes to the side
of the pharynx; it is covered by the trapezius, and passes between the
hypoglossal nerve and the _Aorta ascendens_; arriving at the _Arteria
pulmonalis_, it gives off its terminal branches. [Gaskell has proved
that this nerve contains both sympathetic and vagal elements, and that
it is therefore really a vago-sympathetic.]
[Illustration: Fig. 116.
Right half of skull of _Rana esculenta_, seen from within.
_II_ Optic nerve.
_III_ Motor oculi nerve.
_IV_ Trochlear nerve.
_VN_ Root of the trigeminal nerve.
_Vg_ Gasserian ganglion.
_VS_ Sympathetic nerve.
_VI_ Abducens nerve.
_VII^1_ Facial nerve.
_VIII_ Auditory nerve.
_X^{1–3}_ Pneumogastric and glossopharyngeal nerves.
]
The branches and communications of the pneumogastric nerve are:--
*a.* Communications between the ganglion of the pneumogastric and the
sympathetic system (Fig. 111 _Sp_), which again connect it with the
Gasserian ganglion of the trigeminal nerve (Fig. 111 _VS_, _Vg_); (see
sympathetic system).
*b.* [The _Ramus cutaneus dorsalis_ (Fischer) is considered by Stannius
and Fürbringer to be the homologue of the _Ramus auricularis_; it
passes outwards between the _digastricus_ and _temporalis_ to be
distributed in the skin of the suprascapular region. This nerve is the
persistent portion of the _N. lateralis nervi vagi_ of the tadpole.]
*c.* During its course over the _petrohyoidei_ the vagus gives off a
few twigs (Fig. 114 _pp_), which form a fine plexus to supply these
muscles and the pharynx [also a twig to the trachea, according to
Hoffmann].
*d.* The _Ramus accessorius_ (Fürbringer, Hoffmann, Ecker), (Fig. 114
_XI_) is usually a single small nerve which runs between the
_intertransversarii_ muscles and the _trapezius_: it supplies the under
surface of the latter muscle.
*e.* The _Ramus scapularis_ (Hoffmann) is a very slender nerve arising
near the _Ramus accessorius_; it passes along the under surface of the
_trapezius_ to the inner surface of the _interscapularis_, which it
supplies.
*f.* The _Ramus laryngeus_ (_Recurrens vagi_), (Figs. 114 and 115
_X3l_) runs for some distance parallel to the pneumogastric, separated
from it by the _petrohyoideus IV_; arriving at the hinder cornu of the
hyoid bone the nerve loops round the _Arteria pulmonalis_, and divides
into two branches for the supply of the larynx.
*g.* The _Rami gastrici_ (Fig. 114 _X3g_) are usually two in number:
they pierce the partial diaphragm formed by the anterior fibres of the
_M. obliquus internus_ and terminate in the walls of the stomach.
*h.* The _Rami pulmonales_ (Figs. 114 and 115 _X3p_) also perforate the
partial diaphragm, and then course along the pulmonary arteries to the
lungs.
*i.* The _Ramus cardiacus_ (Figs. 114 and 115 _X3c_). This nerve is
usually smaller on the right side than on the left; it passes along the
dorsal surface of the pulmonary artery and _Vena cava superior_ to the
_Sinus venosus_; in this course it gives off two or three twigs to the
roots of the lungs: the two nerves communicate just before reaching the
heart and pass on to the auricular septum, whence they are distributed
to the heart.
*j.* A slender *Laryngeal nerve* arises from the vagus alongside the
_Ramus cardiacus_; it courses along the hinder end of the greater cornu
of the hyoid to the outer side of the pharynx, which it pierces to pass
to the larynx.
F. THE SPINAL NERVES.
I. *General description.* Ten pairs of nerves arise, as already
described (p. 135), from the spinal cord; each nerve has two roots, a
ventral or anterior, and a dorsal or posterior, which unite at their
points of exit from the intervertebral foramen: just before, and for a
short distance beyond this union, each dorsal root bears a ganglionic
enlargement.
*a.* The length and direction of the various *Nerve-roots* vary
greatly; the roots of the anterior spinal nerves run a very short
course, almost transversely outwards, from their points of origin to
the intervertebral foramina: the roots of the middle and posterior
nerves, in consequence of the vertebral column being considerably
longer than that part of the cord belonging to it, pass obliquely
backwards to the foramina, the hinder nerves of the _Cauda equina_
running for a considerable distance in the vertebral canal (Fig. 116).
The relations of these roots are as follows:--
(1) The roots of the first nerve (_N. hypoglossus_) arise from the
spinal cord at a point between the first and second vertebrae; they run
transversely outwards to escape between the first and second vertebrae.
The dorsal root is extremely slender.
[Illustration: Fig. 117.
The nervous system of _Rana esculenta_, from the ventral surface. (From
Icones physiologicae by A. Ecker. Pl. XXIV, Fig. 1.)
_F_ Facial nerve.
_G_ Ganglion of pneumogastric nerve.
_He_ Cerebral hemisphere.
_Lc_ Optic tract.
_Lop_ Optic lobe.
_M_ Boundary between medulla oblongata and spinal cord.
_M1–10_ Spinal nerves.
_MS_ Connection between fourth spinal nerve and
sympathetic chain.
_N_ Nasal sac.
_Ni_ Sciatic nerve.
_No_ Crural nerve.
_o_ Eyeball.
_S_ Trunk of sympathetic.
_S1–10_ Sympathetic ganglia.
_SM_ Rami communicantes of the same.
_Sp_ continuation of sympathetic into head.
_I_ Olfactory nerve.
_II_ Optic nerve.
_III_ Motor oculi nerve.
_IV_ Trochlear nerve.
_V_ Trigeminal and facial nerves.
_Va_ Ramus ophthalmicus.
_Vc_ Ramus maxillaris.
_Vd_ Mandibular branch of trigeminal.
_Ve_ Hyomandibular branch of facial.
_Vg_ Gasserian ganglion.
_Vs_ Upper end of sympathetic trunk in connection with
Gasserian ganglion.
_VI_ Abducens nerve.
_VII_ Facial nerve.
_VIII_ Auditory nerve.
_X_ Glossopharyngeal and pneumogastric nerves.
_X1_ Ramus anterior of glossopharyngeal.
_X2_ Ramus posterior of glossopharyngeal.
_X3, 4_ Branches of pneumogastric.
]
(2) The roots of the second nerve (_N. brachialis_) arise at the level
of the second vertebra and leave the vertebral canal between the second
and third vertebrae.
(3) The roots of the third nerve arise from the cord between the
second and third vertebrae, and pass out between the third and fourth
vertebrae.
(4) The fourth nerve arises by its two roots at the level of the fourth
vertebra, and quits the vertebral canal between the fourth and fifth
vertebrae.
(5) The fifth nerve arises opposite the fourth vertebra, and passes
outwards and slightly backwards to the foramen between the fifth and
sixth vertebrae.
(6) The roots of the sixth nerve are attached to the cord opposite the
fourth vertebra, and leave the vertebral canal between the sixth and
seventh vertebrae.
(7) The seventh nerve arises from the cord at a point between the
fourth and fifth vertebrae, and leaves the canal between the seventh
and eighth vertebrae.
(8) The eighth nerve quits the cord at a point opposite the
articulation between the fifth and sixth vertebrae, then runs backwards
to the eighth vertebra, and escapes between this and the ninth vertebra.
(9) The ninth nerve arises at the level of the sixth vertebra, and
passes out between the sacrum (ninth vertebra) and the urostyle.
(10) The tenth nerve (_N. coccygeus_) arises from the cord immediately
behind the ninth nerve and opposite the sixth vertebra, and courses
alongside the terminal filament to pass out through a foramen in the
urostyle (_canalis coccygeus_).
*b.* [The *Spinal ganglia* (_Ganglia intervertebralia_).
At their exit from the intervertebral foramen the two roots of each
nerve unite and bear a ganglionic enlargement, which is in intimate
connection with the dorsal root, but is merely in contact with
the ventral root. The ganglia lie[58] in the large intervertebral
depressions, upon the under surface of the _Proc. obliqui_, above and
behind, being in relation with the bodies of the vertebrae internally,
and the _Musculi intertransversarii_ externally (Fig. 119); ventrally
the ganglia are, more or less, covered by the ‘periganglionic glands.’
The ganglia vary much in size; that of the first spinal nerve is the
smallest. The ganglion is not attached to the dorsal root alone but
is prolonged a short distance beyond the point of union of the two
roots; this is best seen in the nerves of the lumbar plexus. Each
ganglion is a yellowish-white rounded or oval body, with an outer thick
(sometimes 0.15 mm. thick) sheath of connective-tissue, connected by
the epineurium of the nerve roots with the _Dura mater_. This sheath is
composed of bundles of parallel, wavy, white, connective-tissue fibres,
which enclose a large number of connective-tissue corpuscles, and here
and there contains brown pigment.
[Footnote 58: The _Gangl. coccygeum_ is in the urostyle.]
[Illustration: Fig. 118.
Ventral view of the brain and spinal cord, to show the points of exit
of the spinal nerves.
_M1–10_ Spinal nerves.
_VG_ Trigeminal ganglion.
_W1–10_ Vertebrae.
_XG_ Ganglion of vagus.
]
By means of longitudinal and transverse sections it may be seen
that the ganglion surrounds the ventral root, but that it forms a
thinner layer on that side, where the dorsal root joins the ventral;
although at this point the two roots and the ganglion are firmly
united together, the thick fibrous sheath of the ganglion prevents any
communication between the nervous elements of the ventral root and
those of the ganglion.
The sheath contains nerve-cells and fibres, and sends in a few fine
processes to support these structures. The fibres of the posterior
root enter and pass out of the ganglion without suffering any changes,
except that the nerve fibres are slightly separated by the presence of
a few nerve-cells, and that a distinct increase in the number of nerve
fibres takes place. The nerve-cells, of which the ganglion is chiefly
composed, and upon the number of which its size directly depends, are
arranged chiefly around the fibres of the dorsal root; such few as lie
between the fibres are smaller than the rest and vary more in their
relative numbers; at times one or two isolated cells are found in the
capsule or even in the adjoining ‘periganglionic gland.’ The cells near
the capsule are somewhat smaller than the deeper cells.[59] Each of
these cells, which are usually pear-shaped, possesses only one process;
the cell membrane is thick, resistant, and possessed of an external
nucleated, endothelial covering, the space around being probably
a pericellular lymph-space; it often contains one to three small
fat-globules; the protoplasm of these has, according to v. Lenhossék, a
concentric fibrillation; the nucleus is round, clear, and distinct, and
relatively larger the smaller the nerve-cell; it is usually placed in
the centre of the cell.
[Footnote 59: Larger cells of deeper layer 80 µ to 90 µ in diameter,
sometimes one or two as large as 0·1 mm. v. Lenhossék.]
[Illustration: Fig. 119.
Ventral view of the spinal ganglia; on the right side they are still
hidden by the ‘periganglionic glands.’ ]
[Illustration: Fig. 120.
Schema of spinal ganglion.
_A_ Ventral root.
_C_ Ramus communicans.
_G_ Ganglion
_O_ Dorsal division.
_P_ Dorsal root.
_R_ Ventral division.
]
In that portion of the cell towards the process is a portion brighter
and less easily stained than the rest of the cell (Polarkernen,
Courvoisier); this apparently possesses one or two nuclei, and is
regarded as a cell by Lenhossék (Polarzellen); the process of each cell
soon acquires a medullated sheath, and after a short course, 0.09 mm.
to 0.35 mm., divides usually about the third constriction (Lenhossék).
These processes all pass peripherally, even those which appear at first
to pass in the opposite direction curve round again; it is chiefly due
to these fibres that the spinal nerve is larger than its two roots.
In addition to the above, smaller, irregular cells from 5 µ to 7 µ in
length are found; Rawitz regards them as young cells, Lenhossék as
cells capable of (entwicklungsfähige) developing into nerve-cells. The
ganglia contain only few blood-vessels.]
The above description is founded upon that of Lenhossék, and has been
confirmed by the translator in every particular, except that only
very indistinct and unsatisfactory indications of the concentric
fibrillation so clearly delineated by Lenhossék were obtained; the
structure of the Gasserian ganglion was found to correspond exactly
with the description here given of the structure of the spinal ganglia.
The nucleus was oftener at the side than at the centre of the cell.
*c.* The ‘*Periganglionic Glands*’ (Periganglionäre Kalkdrüsen, v.
Lenhossék; Kalksäckchen, Ecker, and others; Crystal capsules, Wyman;
Calcareous Sacs or Masses, of other writers), (Fig. 119). These bodies
are found on the ganglia of all the spinal nerves and on the Gasserian
ganglion of the trigeminal nerve; they have recently been carefully
investigated by v. Lenhossék. According to his description there are
usually two to each ganglion, lying on its sides and ventral surface;
each consists of a connective-tissue capsule which sends in a few fine
trabeculae to support a system of glandular tubes: these usually run
parallel to the long axis of the gland, and are about 14 µ to 15 µ in
diameter; each tube is lined with a single layer of somewhat columnar
epithelium, the cells of which have sharp, distinct outlines and oval
nuclei.
A _membrana propria_ was not made out with certainty; the lumen of
the tubes is wide and contains a milky fluid, which gives the whole
structure its characteristic appearance; it has long been known
(Blasius, 1681, mentions the fact, _l.c._, p. 291) that this fluid
contains calcareous matter, which effervesces and dissolves in the
presence of hydrochloric acid; the crystals vary in form but are
chiefly oval (Wyman).
These glands bear no definite proportion to the size of the nerves to
which they are attached (Fig. 118); they already contain calcareous
matter during the tadpole stage before the limbs are developed
(Stannius, Wyman). No ducts have been traced to these glands. This
description, founded upon that of Lenhossék, can be confirmed by the
translator in every particular; his sections, however, would lead him
to believe that the glands are far more vascular than the description
and the drawings of Lenhossék imply.]
*d.* The *Branches* of the complete spinal nerves formed by the union
of the dorsal and ventral roots with the ganglion (Fig. 120) are
usually described as two, a dorsal and a ventral branch, which latter
at once gives off a _Ramus communicans_ to the sympathetic system;
these two branches are given off almost immediately beyond the ganglion.
II. The Individual Nerves.
A. The Dorsal Branches (Fig. 121).
[Illustration: Fig. 121.
Dorsal branches of the spinal nerves. The _Fascia dorsalis_ is
dissected, removed from the left side.
_rc_ Rami cutanei.
_rm_ Rami musculares.
]
The dorsal branches are smaller than the ventral; they pass upwards
between the inner borders of the _Musc. intertransversarii_ and the
articular processes of the vertebrae to reach the under surface of the
_M. longissimus dorsi_; the general course of these nerves is very
similar for all; each nerve gives off--
(_a_) A twig to the _Musc. intertransversarius_ and then divides into
two branches.
(_b_) A _Ramus muscularis_ (Fig. 121 _rm_), which passes outwards to
supply the _M. longissimus dorsi_.
(_c_) A _Ramus cutaneus_ (Fig. 121 _rc_); this nerve continues under
the extensor muscle of the back, running on the arch of the vertebra
towards the middle line; it then pierces the muscle and Fascia dorsalis
to reach the large dorsal lymph-sac (_Sacc. cranio-dorsalis_), through
which it courses to end in the skin. In its course through the sac the
nerve is connected with a small artery and vein by a small amount of
connective-tissue, the whole being enclosed in a sheath of endothelium
continuous with that of the general cavity.
The three anterior cutaneous nerves pierce the _Fascia dorsalis_ near
the spinous processes, the fourth a little to the side, the fifth
perforates the _M. coccygeo-iliacus_ at about the junction of its
anterior and middle thirds; the sixth and seventh perforate the same
muscle, but more posteriorly. There are seven of these _Rami cutanei_,
the first coming from the second spinal nerve, the rest from the
succeeding six spinal nerves.
B. The Ventral Branches.
The ventral branches of the spinal nerves are larger than their
corresponding dorsal branches: each nerve gives off immediately a
_Ramus communicans_ to the sympathetic system (Figs. 117 _SM_, 120
_C_); these _Rami communicantes_ will be described with the sympathetic
system; the remaining portions of the ventral divisions of the original
spinal nerves are usually known as the spinal nerves; they will be
described as such in detail.
*1.* The *hypoglossal nerve*[60] (_N. hypoglossus_, _N. spinalis I_),
(Figs. 114 115, and 117 _M1_), or first spinal nerve, is of small
size; it leaves the vertebral canal between the first and second
vertebrae to lie between the _Musculi intertransversarii_ and the
pharynx, where it has in front the _Arteria vertebralis_, behind the
_Arteria_ and _Nervus brachialis_; passing under the _Levator anguli
scapulae_, it touches the _Aorta ascendens_ and crosses the _Vagus_
and the Carotid-gland, and thus reaches the space between the _Musculi
sterno-hyoidei_ and the _Petro-hyoideus_; then curving forwards sharply
it turns under the _Mylo-hyoideus_ to course between the fibres of the
_Genio-hyoideus_ to the root of the tongue, where it ends. It first
lies to the inner and then to the outer side of the glossopharyngeal
nerve. In its course the nerve gives off the following branches:--
[Footnote 60: [Observers have differed considerably as to the relations
of this nerve: Volkmann describes it as the first nerve of the neck,
and describes a ganglion on its dorsal root; Vogt denies the presence
of this ganglion, and regards it as a true cranial nerve; Stannius
asserts that no ganglion exists, and holds the nerve to represent the
first two spinal nerves; Wyman describes the two roots and regards it
as a spinal nerve; Hoffmann regards this nerve as the second spinal
(N. spinalis II); Fürbringer as the representative of two spinal
nerves; de Watteville describes two roots and names it first spinal
nerve.--TRANS.]]
(_a_) One or two communicating twigs (Figs. 114 and 122) to the second
spinal nerve.
(_b_) Muscular twigs to the _Longissimus dorsi_, _Intertransversarii
capitis_, _Levator anguli scapulae_, and the _Retrahens scapulae_.
(_c_) When near the glossopharyngeal it supplies twigs to the
_Geniohyoideus_, _Sternohyoideus_, and _Omohyoideus_, where it
bifurcates.
(_d_) One of the branches passes inwards to supply the _Hyoglossus_.
(_e_) The other terminal branch passes forwards with the _Ramus
lingualis_ and the glossopharyngeal, between the fibres of the
_Geniohyoideus_, which it partially supplies, and sends twigs to the
neighbouring parts.
(_f_) [Hoffmann describes a communicating branch to the pneumogastric
nerve, which the translator has not been able to discover, and which no
other observer has mentioned.]
*2.* The *second spinal* or *brachial nerve* (_N. brachialis_, _N.
spinalis II_), (Fig. 122) is a large nerve, leaving the vertebral canal
between the second and third vertebrae; it then accompanies the _Art.
axillaris_ along the anterior border of the transverse process of the
third vertebra, over the hinder end of the _Musc. levator scapulae_ and
the anterior end of the _m. transverso-scapularis major_, to the inner
border of the _Musc. subscapularis_, under which it passes into the
arm. In this course it gives off or receives the following branches:--
(_a_) It first receives a branch from the second spinal nerve.
(_b_) It gives off a large branch, the _N. coraco-clavicularis_
(Fig. 122 _Cc_), which first accompanies a branch of the _Art.
axillaris_ on the _Musc. levat. scapulae_, then courses forwards and
outwards over the _Musc. subscapularis_ to pass from above into the
_Foramen ovale_ between the clavicle and coracoid bones. It gives off
two branches:
(1) One immediately beyond its origin, which runs backwards over the
_Musc. subscapularis_ to supply the _Musc. obliq. abdominis internus_
(Fig. 122 _Cc_′).
(2) While in the _Foramen ovale_, the _N. coraco-clavicularis_
bifurcates; the anterior twig runs forwards and outwards to the
_deltoideus_ and also supplies a recurrent filament to the _Musc.
sterno-radialis_; the posterior twig enters the upper surface of the
_Musc. stero-radialis_.
(_c_) At the outer extremity of the _Musc. transverso-scapularis_ the
brachial nerve gives off a posterior branch, which at once bifurcates:
(1) The first branch passes into the under surface of the _Musc.
latissimus dorsi_ (_ld_), giving a twig to the _Infraspinatus_.
(2) The second is the _Ramus cutaneus axillaris_ (_IIc_); it passes on
the under surface and posterior border of the _Musc. latissimus dorsi_
to the skin of axilla and dorsal surface of the upper arm.
(_d_) Several small branches are given off from the upper and anterior
surfaces of the brachial nerve near the _Foramen ovale_; they
accompany an artery to pass forwards and upwards between the _Musc.
subscapularis_ and the _M. transverso-scapularis_ on the one side, and
the long head of the _M. triceps brachialis_ on the other, and are lost
in the _M. deltoideus_ and the _M. infraspinatus_.
[Illustration: Fig. 122.
The brachial plexus.
_Cc_ N. coraco-clavicularis.
_Cc_′ Nerve to musc. obliq. abdom internus.
_d_ Deltoid muscle.
_la_ Musc. lev. ang. scap.
_ld_ Musc. lat. dorsi.
_oi_ Musc. obliq. abdom. intern.
_sc_ Musc. sterno-mastoid.
_ss_ Musc. subscapularis.
_SI_ First spinal nerve.
_SII_ Second spinal nerve.
_SIII_ Third spinal nerve.
_IIc_ Ramus cutaneus axillaris.
_IIIc_ Ramus cutaneus abdominalis.
]
The _N. brachialis_ continues its course by passing between the long
and inner heads of the _M. triceps_, reaches the arm and splits into
two nerves, the _N. ulnaris_ and the _N. radialis_.
[*I.*] The _N. ulnaris_ (Fig. 123 _U_) escapes from cover of the long
head of the _M. triceps_ and runs obliquely over its inner head
towards the outer side of the _Plica cubiti_; in this course it
supplies four branches:
α. The _Ramus subscapularis_ passes dorsally to the _M. subscapularis_.
β. A _Ramus pectoralis_ (Fig. 123 _up_), passes forwards to the _M.
abdomino-pectoralis_ and to the skin of the pectoral region (_R.
cutaneus pectoralis_).
γ. The _N. cutaneus antibrachii superior s. medialis_ (_uc_) passes to
the skin of the inner side of the forearm; this and the two following
nerves are given off near the _Plica cubiti_.
[Illustration: Fig. 123.
Nerves of the central surface of the arm. The hand pronated.
_rc_ Upper cutaneous branch of the N. radialis.
_rc_′ Lower cutaneous branch 4-,f the N radialis
_U_ N. ulnaris.
_uc_ R. cutan. sup. of the N. ulnaris.
_uc_′ R. cutan. inf. of the N ulnaris.
_up_ R. pectoralis of the N. ulnaris.
]
δ. The _N. cutaneus antibrachii inferior s. dorsalis s.
musculo-cutaneus_ (_uc_′) at once supplies branches to the _M. flexor
carpi radialis_[61], and then runs downwards upon the muscle and
bifurcates:--
[Footnote 61: As this muscle increases in size during the breeding
season. it would be interesting to know whether a corresponding change
takes place in the nerve.]
[1] The _R. lateralis_ is distributed, by two twigs, in the _M. flexor
carpi ulnaris_ and in the skin of the second finger, to which it
supplies the _Rami digitales volaris_ and _dorsalis_.
[2] The _R. dorsalis_, after giving a cutaneous twig to the second
finger, is distributed by numerous twigs to the skin of the dorsal
surface of the hand.
The _N. ulnaris_ then passes between the _M. flexor carpi radialis_ and
the tendon of the _M. sterno-radialis_, sinks deeply into the _Plica
cubiti_, where it lies between the _M. flexor carpi radialis_ and
the _Flexor carpi ulnaris_, then between the latter and the _Flexor
anti-brachii medialis_ on the one side and the _Flexor digitorum
communis_ on the other: it supplies branches to all these muscles, and
while still in the forearm divides into two terminal branches:--
α. The _R. ulnaris medialis_ is the smaller; it runs inwards, passes
under the tendon of the _M. extensor carpi ulnaris_ into the palm of
the hand and ends as the _N. volaris digiti V medialis_.
β. The _R. ulnaris lateralis_ passes near the thumb-rudiment, covered
by the _M. abductor pollicis_, deeply into the palm of the hand, and
supplies by bifurcating branches the adjacent sides of the second,
third, fourth, and fifth fingers (_R. volares_); it also gives twigs to
the muscles of the palm.
[II.] The _N. radialis_ (Figs. 123, 124, and 125 _R_) passes immediately
beyond its origin from the _N. brachialis_, between the humerus and the
_M. triceps_, runs along the bone to its outer side; in this course it
gives off:--
[Illustration: Fig. 124.
Nerves of the ventral surface of the arm. The hand supinated, and the
superficial layer (Flex. carpi rad. and uln., Flex. dig. commun.) has
been removed.
_R_ N. radialis.
_u_ N. ulnaris.
_uc_ R. cutan. inf. of the N. ulnaris.
_um_ Bifurcation of the N. ulnaris.
]
α. _Rami musculares_ to the separate parts of the _M. triceps_.
β. The _Ramus cutaneus superior_ (Fig. 125 _rc_) to the skin of the
outer surface of the upper arm and forearm.
The nerve then sinks deeply under the origins of the _M. extensor carpi
ulnaris_ and the _M. extensor digitorum communis_, where it bifurcates
after giving off some small twigs:--
γ. Small muscular twigs to the extensor muscles of the hand and fingers.
[Illustration: Fig. 125.
The N. radialis.
_ec_ M. extensor carpi ulnaris.
_ed_ M. extensor digit. comm.
_R_ N. radialis.
_R1_ R. lateralis.
_R2_ R. medialis.
_rc_ R. cutaneus superior.
_rc_′ R. cutaneus inferior.
]
δ. The _R. radialis medialis_ (_R2_), the smaller terminal branch,
supplies a branch to the _M. extensor digit. comm. longus_ and the skin
over the carpus (_Ramus cutaneus inferior_, _rc_′), and ends on the
muscles of the little finger as the _R. dorsalis digiti V medialis_.
ε. The _R. radialis lateralis_ (_R_), the larger of the two branches,
supplies the extensor muscles of the fingers and gives bifurcating
branches, _Rami digitales dorsales_, to the adjacent sides of the
second, third, fourth, and fifth fingers (the _Ramus dorsalis
lateralis_ of the second finger is supplied by the _N. ulnaris_).
*3.* The *third spinal nerve* (_N. spinalis III_) (Fig. 122 _SIII_)
leaves the vertebral canal by the foramen between the third and fourth
vertebrae, and runs outwards and forwards upon the large transverse
process of the third vertebra to the brachial nerve (_N. spinalis II_).
Its behaviour at this point is subject to considerable variation; at
times it joins the brachial nerve completely, at other times the two
nerves are simply in contact; or lastly, it may send a small twig to
the brachial nerve. Externally to this point the two nerves supply a
number of small branches, which may belong almost entirely to either
one nerve or the other; these nerves again inosculate in a variable
manner, to form an axillary plexus. The more constant branches are:--
(1) One or more twigs to the _Musc. transverso-scapularis major_.
(2) Several branches, usually two larger and one smaller; they course
in the _M. obliq. abdom. internus_ (Fig. 122 _oi_) to the _M. rectus_,
where they give off branches, then pierce the muscle to reach the skin
(_R. cutaneus abdominalis_), (Fig. 122 _IIIc_).
*4.* The *fourth spinal nerve* (_N. spinalis IV_) (Fig. 126 _M4_)
appears between the fourth and fifth vertebrae; it runs on the ventral
surface of the transverse process of the fifth vertebra and upon the
_Musc. intertransversarius_ obliquely outwards and downwards, and
reaches the deeper surface of the _Musc. obliquus internus_, into which
it descends, about opposite the articulation between the eighth and
ninth vertebrae; it then bifurcates into:--
(1) A _Ramus cutaneus abdominalis_, which pierces the muscle and
supplies the skin.
(2) A _Ramus muscularis_, which supplies the broad abdominal muscle and
the _M. rectus abdominis_.
*5.* The *fifth spinal nerve* (_N. spinalis V_) (Fig. 126 _M5_)
emerges through the foramen between the fifth and sixth vertebrae,
runs obliquely downwards and outwards over the transverse processes
of the sixth and seventh vertebrae and the corresponding _M.
intertransversarii_, and at a point nearly opposite the middle of the
urostyle pierces the _M. obliquus internus_.
The rest of its course corresponds exactly with that of the fourth
spinal nerve.
*6.* The *sixth spinal nerve* (_N. spinalis VI_) (Fig. 126 _M6_),
after escaping from the vertebral canal between the sixth and seventh
vertebrae, runs obliquely downwards and outwards on the under
surfaces of the transverse processes of the seventh, eighth, and
ninth vertebrae, then under the iliac bone to a point opposite the
hinder half of the urostyle, where it descends under cover of the _M.
obliquus abdom. internus_. In the rest of its course it repeats the
corresponding courses of the fourth and fifth spinal nerves.
[Illustration: Fig. 126.
Ventral view of the brain and spinal cord, to show the points of exit
of the spinal nerves.
_M1–10_ Spinal nerves.
_VG_ Trigeminal ganglion.
_W1–10_ Vertebrae.
_XG_ Ganglion of the vagus.
]
*7*, *8*, *9*, and *10*. The *seventh*, *eighth*, *ninth*, and *tenth
spinal nerves* (_Nervi spinales VII_, _VIII_, _IX_, and _N. spinalis X
s. N. coccygeus_) (Figs. 126 and 127 _M7_, _M8_, _M9_, and _M10_) are
best described together, as they are intimately associated to form the
sciatic plexus (_Plexus ischiadicus_, _Plexus cruralis_).
Within the vertebral canal the roots of these nerves form the _Cauda
equina_; the seventh nerve leaves the canal between the seventh and
eighth vertebrae, the eighth nerve between the eighth and ninth
vertebrae, the ninth between the sacrum or ninth vertebra and the
urostyle, and the tenth by the _Canalis coccygeus_ in the urostyle;
from these points the four nerves run obliquely on the ventral surface
of the _M. ilio-coccygeus_ to the pelvis, where they form the sciatic
plexus. Although subject to some variation, the usual arrangement is
that the seventh and eighth nerves unite to form a trunk, which then
receives the ninth nerve; the large nerve so formed is the sciatic
nerve: a branch of the tenth usually then joins either the sciatic
plexus or the sciatic nerve; the plexus gives off or receives the
following branches:--
(_a_) Like other spinal nerves, these nerves give off _Rami
communicantes_ (see Sympathetic System).
(_b_) The _M. ilio-hypogastricus_ (Fig. 127 _M7a_). This arises
from the seventh spinal nerve, before its union with the eighth
spinal nerve; it runs obliquely outwards and downwards on the _Musc.
ilio-coccygeus_ and under the border of the _M. obliquus abdom.
internus_, where it bifurcates:--
(1) One branch, the _Ramus cutaneus abdominalis_, pierces the _M.
obliq. abdom. internus_ in the same fashion as the cutaneous branches
of the fourth, fifth, and sixth spinal nerves; it supplies the skin of
the abdomen.
(2) The second or _Ramus muscularis_ supplies the flat abdominal
muscles and the _M. rectus abdominis_.
(_c_) The _M. cruralis_ (Fig. 127 _M7b_) also arises from the seventh
spinal nerve at or just beyond its point of union with the eighth
spinal nerve. It accompanies the _A. cruralis_ on the pelvic wall to
the thigh, where it lies upon the _M. ilio-psoas_ in a triangle between
the _M. rectus fem. anterior_ and the _M. adductor longus_, and divides
into two main branches:--
(1) Muscular twigs to the _M. ilio-psoas_, _M. rectus femoris anticus_,
_MM. adductores longus_ and _brevis_.
(2) The _Ramus cutaneus femoris_, which runs downwards in the hinder
wall of the Lymph-sac (_Saccus iliacus_), and supplies the skin of the
under and outer surfaces of the thigh.
[Illustration: Fig. 127.
The sciatic plexus, from a drawing by Wiedersheim.
_a_ Communicating nerve from the ninth spinal nerve.
_a_′ Nerve to musc. lev. ani.
_b_ Nerve to oviduct.
_c_ Urostyle.
_cc_ Communicating twig from the ninth spinal nerve.
_ci_ M. coccygeoiliacus.
_c.I_ M. coccygeosacralis.
_d_ Nerve to bladder.
_d_′ Twig to the m. iliacus.
_e_ Twig from sciatic plexus to coccygeal plexus.
_i_ M. intertransversarius.
_il_ M. ilio-coccygeus.
_ip_ M. ilio-psoas.
_lev_ M. lev. ani.
_oi_ M. obliq. abdom. internus.
_t_′ Transverse process of sacrum.
_Ao_ Aorta.
_Com_ Point of union of nerves _a_ and _cc_.
_Is_ Ischium.
_M5_ Fifth spinal nerve.
_M6_ Sixth spinal nerve.
_M7_ Seventh spinal nerve.
_M8_ Eighth spinal nerve.
_M9_ Ninth spinal nerve.
_M10_ Tenth spinal nerve.
_M7a_ M. iliohypogastricus.
_M7b_ M. cruralis.
_Ni_ Sciatic nerve.
_Ovd_ Oviduct.
_Rect_′ Rectum.
_S7_, _S8_, _S9_, _S10_ Rami communicantes of seventh,
eighth, ninth, and tenth spinal nerves.
_Ves_ Bladder.
8, 9 Eighth and ninth vertebrae.
]
(_d_) The _Ramus dorsalis_ is a very small nerve; according to Waldeyer
it possesses only twenty nerve-fibres. It arises from the coccygeal
nerve immediately beyond the _Canalis coccygeus_, perforates the _M.
ilio-coccygeus_, and runs on its dorsal surface obliquely over the
lymph-heart, without supplying it; the nerve then pierces the fascia to
supply the skin of the back and thigh.
(_e_) The _Ramus abdominalis_ also arises from the coccygeal nerve; it
is larger than the _R. dorsalis_, and arises at the same point; the
nerve runs on the ventral surface of the _M. ilio-coccygeus_ towards
the lymph-heart, and inosculates with the sympathetic. It is from this
nerve that the branch to the sciatic plexus is usually given off; it
further supplies a varying number of branches, which with branches
derived directly or indirectly from the sciatic nerve, form a plexus
(_Plexus coccygeus_); the two plexuses may together be regarded as a
_Plexus ischio-coccygeus_ or a _Plexus sacro-coccygeus_.
(_f_) In addition to the _Rami communicantes_ given off by the spinal
nerves near the vertebral column, the sciatic plexus supplies a few
twigs, usually two (Fig. 127).
(_g_) Other small twigs pass from the sympathetic system forwards and
outwards to join the sciatic plexus or the sciatic nerve. According to
Waldeyer two of these are very constant.
(_h_) Branches to the oviduct (Fig. 127 _b_).
(_i_) Branches to the rectum (Fig. 127 _cc_).
(_k_) Branches to the bladder (Fig. 127 _d_).
(_l_) Branches to the _M. levator ani_ (Fig. 127 _a_′).
(_m_) A branch to the lymph-heart, which runs along the anterior border
of the _M. lev. ani_, on to its dorsal surface, and then direct to the
lymph-heart.
*Variations* in the *sciatic plexus*. The arrangement of the nerves
in the sciatic plexus is subject to many variations; according to
Wiedersheim most of these variations belong to two chief classes:
either the _N. coccygeus_ inosculates directly with the ninth
spinal nerve by one or several branches, or it joins the ninth
nerve indirectly by uniting with its branches. A case of the latter
arrangement is seen in Fig. 127, and is thus described by Wiedersheim:--
‘After cutting through the pelvic symphysis and drawing to one side
the contained viscera, namely, the hinder end of the oviduct, the
rectum, and the bladder, one sees a row of small twigs (_a_, _b_, _cc_,
_d_, and _e_) arising from the inner, hinder, and anterior surfaces
of the ninth spinal nerve: the first (_a_) runs backwards parallel
with the _N. coccygeus_ over the _M. ilio-coccygeus_ to join this
nerve at the point marked _Com_. The twig _cc_ behaves in like manner
after receiving a twig from _b_. The twig _b_ arises from the inner
surface of the ninth nerve between the two foregoing and close to its
union with the eighth spinal nerve; from this origin twig _b_ passes
almost transversely outwards to the hinder extremity of the oviduct
(“uterus”), and partly to the rectum, crossing in its course twig _a_,
the sciatic nerve, and the urostyle. Its branches form a net-like
plexus with the terminal branches of the last sympathetic ganglion and
with a branch _cc_ from the point of union _Com_.
‘A second branch (_a_′), arising from the point of junction _Com_, is
a continuation of the _N. coccygeus_ (_M10_); it passes vertically
downwards towards the hinder end of the cloaca and at the upper border
of the _Levator ani_, divides into two branches, which are distributed
to the inner and outer surfaces of this muscle and to the cloaca. Other
branches pass dorsally to the lymph-hearts, while a third set pass to
the hindermost part of the bladder.
‘These three sets of nerves, to the _M. coccygeus_, _M. levator
ani_, and to the lymph-hearts, are not supplied entirely by the _N.
coccygeus_, as this is reinforced by one or more branches (_e_) from
the sciatic plexus: this branch (_e_) supplies twigs to the _M.
ilio-coccygeus_, which is also supplied anteriorly from the trunk of
the _N. coccygeus_.
‘The bladder receives a special branch (_d_), which arises from the
sciatic plexus at the junction of the eighth and ninth spinal nerves;
this nerve gives a twig (_d_′) to the _M. iliacus_.’
*I.* The *sciatic nerve* (_N. ischiadicus_) (Fig. 128 _I_) is the
largest nerve of the body; it passes under the _M. coccygeus_, between
the origins of the _M. vastus externus_ and of the _M. pyramidalis_:
lies then between the _M. biceps_ and the _M. pyramidalis_, and later
between the _M. biceps_ and the _M. semimembranosus_; lastly, it
bifurcates under the _M. biceps_ to form the _N. tibialis_ (_II_) and
the _N. peroneus_ (_III_). In this course it gives off:--
(_a_) A twig to the _M. coccygeo-iliacus_, while still in the pelvis.
(_b_) The _N. cutaneus femoris posterior_ (Fig. 128, 2), which passes
between the _M. pyramidalis_ and the _M. vastus externus_, to appear
behind and beneath the former; it accompanies an artery of like name to
supply the skin of the hinder and inner surfaces of the thigh.
(_c_) A little below the foregoing it gives off a collateral branch
(Fig. 128, 3), which passes under the _M. pyramidalis_ and divides to
form--
(1) A branch to the upper third of the _M. semimembranosus_.
(2) A branch to the _Rectus internus minor_. A twig of this branch
(_bb_) pierces the muscle transversely in company with the _Arteria
cutanea_, and passes to the skin of the middle of the inner surface of
the thigh.
(3) Branches to both heads of the _semitendinosus_.
(4) Branches to the _M. adductor magnus_.
(_d_) Branches covered by the _M. pyramidalis_ to the _M. quadrat.
femoris_ and _M. obturator_.
(_e_) A branch (5) forwards to the _M. biceps_.
(_f_) A branch (6) which accompanies the _Art. circumflexa genu
lateralis sup._ forwards to the _M. extensores cruris_, the _M. vastus
externus_, and the _M. rectus anterior_.
[Illustration: Fig. 128.
Distribution of the sciatic nerve.
_I_ The sciatic nerve.
_II_ N. tibialis.
_III_ N. peroneus.
1 Branches to the M. pyramidalis.
2 N. cut. fem. posterior.
3 Large collateral branch.
5 Branch to the M. biceps.
6 Branch accompanying the art. circumfl. genu lateralis sup.
7 Branch of tibial nerve to the M. gastrocnemius.
8 N. suralis.
_ad_‴ M. adductor magnus.
_b_ M. biceps.
_bb_ Twig accompanying the art. cutanea.
_ci_ M. coccygeo-iliacus.
_cp_ N. cut. cruris lateralis.
_ct_ R. cut. cruris posterior.
_g_ M. gastrocnemius.
_gl_ M. glutaeus.
_p_ M. pyramidalis.
_pe_ M. peroneus.
_ra_ M. rectus anterior.
_ri_′ M. rectus internus minor.
_sm_ M. semimembranosus.
_st_ M. semitendinosus.
_ve_ M. vastus externus.
]
*II.* The _Nervus tibialis_ (Figs. 128 _II_, 129 _T_) passes backwards
and inwards to supply the extensors of the foot and the flexors of the
toes. Its branches are:--
(_a_) The _R. cutaneus cruris posterior_ (Figs. 128 and 129 _ct_),
accompanied by an artery and vein, passes to the skin of the calf.
(_b_) A twig to the upper part of the gastrocnemius (Fig. 129 _g_′).
The main nerve, after supplying this twig, bifurcates to form the next
two nerves.
(_c_) The _Nervus suralis_ (Figs. 128 8; 129 _s_) runs downwards on the
inner border of the _M. gastrocnemius_ and gives off:--
(1) A twig (_g_″) to the upper third of the muscle.
[Illustration: Fig. 129.
Nerves of the leg and sole of the foot.
_ab5_ Branch to the M. abduct. digit. V.
_ad5_ Branch to the M. adduct. digit. V.
_ar_ M. rectus anterior.
_b_ M. biceps.
_cs_ Ramus cutaneus medius.
_ct_ Ramus cutaneus cruris posterior.
_dvI_ Ramus digitalis volaris I.
_dvII_ Branch supplying R. digit. volaris I and II.
_dvIII_ Second branch of the N. tibialis.
_F5_ Branch to the M. flex. brev. digit. V.
_flp_ Branches to the M. plantaris and the M. flexor digitorum.
_g_′ Branch to the M. gastrocnemius.
_g_″ Branch to the M. gastrocnemius.
_pc_ N. peroneus.
_s_ N. suralis.
_sm_ M. semimembranosus.
_T_, _t_ Nervus tibialis.
]
(2) The _Ramus cutaneus medius_ (_cs_) is given off below the middle
of the _M. gastrocnemius_; it passes to the skin of the lower third
of the leg. After giving off the latter branch, the _N. suralis_
runs downwards along the inner aspect of the _Tendo achillis_ to the
_Aponeurosis plantaris_ of the sole of the foot as far as the calcar,
and gives off:--
(3) Branches (_flp_) to the _Musc. plantaris_ and the _M. flexor
digitorum_.
(4) A branch to the _M. abductor hallucis_.
(5) The _R. digitalis volaris I_ (_dvI_) supplies the inner side of the
first toe by its terminal twig.
(_d_) The _Nervus tibialis_ (Fig. 129 _t_) passes downwards on the
hinder surface of the tibio-fibula, sinks into the _M. tibialis
posticus_ to appear again at its hinder border; it then runs over the
ankle-joint into the sole of the foot, where it lies midway in the
space between the two _Ossa tarsi_ and between the _M. extensor tarsi_
and the _M. abductor digiti I longus_; the nerve then runs downwards in
the groove of the small _Os tarsi_ and divides to form three branches:--
(1) The first branch (_dvII_) runs to the space between the second and
third fingers, where it bifurcates:--
(α) The _Rami digital. volaris I_ run transversely over the muscles of
the second toe, supply the muscles of the first toe, and bifurcate to
form the _R. digital. volaris I_ and _II_.
(β) The _Ram. digit. volar. II_ divides in the space between the second
and third fingers to supply the _Flex. phalang._ and the adjacent sides
of these toes.
(2) The second branch (_dvIII_) runs over the _M. flex. metatarsi_
of the third toe to the space between the third and fourth toes, and
bifurcates to supply the adjacent sides of these toes and the web
between them.
(3) The third branch at once divides to supply:--
(α) The _M. transv. metatarsi_.
(β) The _MM. lumbricales_ of the fourth toe.
(γ) The _M. abductor digit. V_ (_ab5_), the _M. flexor brevis dig. V_
(_F5_), and the _M. adductor dig. V_ (_ad5_); it then ends as--
(δ) A bifurcating branch forming the _R. digit. volar._ of the fourth
and fifth toes.
*III.* The _Nervus peroneus_ (_N. peroneus communis superior_,
Ecker), (Fig. 130 _pc_) is the second division of the sciatic nerve;
it passes between the outer head of origin of the _M. gastrocnemius_
and the tendon of insertion of the _M. biceps_, it then lies on the
tibio-fibula between the _M. gastrocnemius_ and the _M. peroneus_,
where it is accompanied by the _Vena tibialis postica_, then runs
downwards upon the _M. extensor cruris_ and the _Flexor tarsi ant._,
and passes under the _M. tibial. anticus_ and bifurcates; its branches
are:--
*a.* The _N. cutaneus cruris lateralis_ (Fig. 128 _cp_); which, like
other cutaneous nerves, runs in a common sheath together with an artery
and vein to the skin. It arises close to the sciatic nerve.
*b.* Muscular branches to the _MM. peroneus_, _tibialis anticus_,
_extensor cruris brevis_, and the _flexor tarsi anterior_.
[Illustration: Fig. 130.
Distribution of the _N. peroneus_.
_A_ Inner terminal twig of N. peron. comm. inf.
_B_ Outer terminal twig of N. peron. comm. inf.
_cpl_ N. cutaneus dorsi pedis lateralis.
_pc_ N. peroneus.
_pci_ N. peroneus communis inferior.
_pl_ N. peroneus lateralis.
_pm_ N. peroneus medialis.
]
*c.* The _N. peroneus medialis_ (Fig. 130 _pm_) is the smaller of
the two terminal branches of the _N. peroneus_; it courses with the
_Art. tibialis antica_ under the _MM. flexores tarsi anterior_ and
_posterior_ and supplies the latter.
*d.* The _N. peroneus lateralis_ (Fig. 130 _pl_) is the larger terminal
branch of the _N. peroneus_; it passes downwards between the heads of
the _M. tibialis anticus_ to the tendon of origin of the _Flexor tarsi
posterior_, where it gives off two branches (Nos. 1 and 2); the nerve
then unites with the _N. peroneus lateralis_ to form a common stem, the
_N. peroneus communis inferior_ (Ecker). The _N. peroneus lateralis_
gives off:--
(1) The _N. cutaneus dorsi pedis lateralis_ (_cpl_), which passes to
the skin of the outer side of the dorsum of the foot.
(2) A second branch to the _M. extensor_ of the fourth and fifth toes.
*e.* The _N. peroneus communis inferior_ (Fig. 130 _pci_) runs on
the dorsum of the foot in company with the _Art. dorsalis pedis_,
underneath the _MM. extensores digiti I_ and _II_; it supplies several
branches and then bifurcates. It gives off:--
(1) Branches to the _MM. extensor longus_ and _brevis digiti I_.
(2) _Rami digitales dorsales_ to the adjacent sides of the first and
second toes.
(3) Branches to the _MM. extensores digiti II_.
(4) The inner, terminal branch (Fig. 130 _A_) at once divides:--
(α) The outer branch runs between the third and fourth toes as far as
the commencement of the web, where it bifurcates to form two _Rami
cutanei_, which course along the adjacent sides of these toes as far as
their apices.
(β) The inner branch passes to the extensor muscle, and, in part, to
the adjacent sides of the third and fourth toes.
(5) The outer, terminal branch (Fig. 130 _B_) of the _N. peroneus
communis inferior_ passes to the muscles of the fourth and fifth toes,
and supplies _Rami cutanei dorsales_ to the outer side of the fourth
and inner side of the fifth toes.
Cutaneous branches of the _N. tibialis_ supply the outer side of the
fifth and inner side of the first toe.
G. THE SYMPATHETIC SYSTEM (_Sympathicus_).
_(Re-written by the translator.)_
The *sympathetic cord* or *chain* is a row of nervous ganglia
(vertebral or lateral ganglia), connected by nerve-fibres, and lying
on either side of the vertebral column (Figs. 117 and 131); with the
exception of the last spinal nerve there is usually one sympathetic
ganglion associated with each spinal nerve; in the case of the tenth
spinal nerve there may be only one ganglion or as many as twelve.
The first ganglion (Figs. 111, opposite _ics_; 117 _S_1) is placed on
the hypoglossal nerve just as it emerges from the first intervertebral
foramen; it is large, but smaller than the second; its _Ramus
communicans_ is represented by several fine and very short fibres,
which connect the ganglion with the nerve. This ganglion is connected
with the second by two or three nervous threads, between which passes
the subclavian artery, a true _Annulus Vieussenii_ being thus formed
(de Watteville). The other ganglia are connected by single bands of
fibres. The first ganglion supplies also branches to the axillary
artery and to the cardiac plexus.
The second ganglion (Figs. 117 and 131) is the largest, and is closely
applied to the brachial nerve; as in the case of the first ganglion and
hypoglossal nerve, it is attached to the second spinal nerve without a
distinctly marked _Ramus communicans_.
The third ganglion (_Ganglion cardiacum basale_, Gaskell and Gadow)
is sometimes fused with the second, but is usually close to the third
spinal nerve: it has a short but distinct _Ramus communicans_.
[Illustration: Fig. 131.
Sympathetic cord. From Ecker (Icones physiologicae, Pl. XXIV, Fig. 3).
The heart, lungs, and liver have been removed; the stomach, intestine,
kidneys, and testes drawn to the right side; the left sympathetic cord
is thus pulled to the right side to expose the Rami communicantes.
_S_ Sympathetic cord attached to the ganglion of the vagus.
The numbers refer to the ganglia, which are enumerated from before
backwards.
]
Behind the third ganglion the sympathetic cord is continued backwards
along the corresponding aortic arch, then parallel with and close
to the abdominal aorta (Figs. 117, 127, and 131), receiving _Rami
communicantes_, which are long and well marked, from each of the spinal
nerves; the fourth, fifth, and sixth nerves usually supply each one
_Ramus communicans_, the seventh two, and the eighth and ninth each
two or three: from the tenth nerve it receives three or more, as many
as twelve having been noted. The ganglia are usually more or less
spindle-shaped or flattened and triangular; the hinder part of the cord
usually receives in addition two or three branches from the sciatic
plexus and twigs from the _R. abdominalis_ of the _N. coccygeus_.
The branches and communications of the sympathetic cords are as
follows:--
*a.* Communicating branches between the two cords; these are extremely
numerous and irregular, forming a net-like plexus, which surrounds the
abdominal aorta and other adjacent structures, and gives off numerous
small twigs to the neighbouring vessels and organs.
*b.* Communications with the cranial nerves; these are two branches
(Wiedersheim), (Figs. 111 and 116) which pass from the first ganglion
to the _Ganglion nervi vagi_, where one terminates, the other leaves
the ganglion to pass on to the Gasserian ganglion (Figs. 111 and 116
_VS_): according to Gaskell a _single_ nerve passes from the first
ganglion to the _Ganglion nervi vagi_, whence one portion of its fibres
is continued to the Gasserian ganglion, the remainder accompanying
the pneumogastric nerve without any connection with the ganglion;
he therefore names this nerve the vago-sympathetic. (See Gasserian
ganglion, p. 168.)
*c.* Communications with the spinal nerves; these are:--
(1) The _Rami communicantes_.
(2) Communications between the sympathetic ganglia or their branches
and the spinal nerves or their branches (Fig. 117); by means of these
connections, fibres of the sympathetic system are conducted by the
spinal nerves and their branches to all parts of the body.
*d.* Branches to the heart, which form the following ganglia:--
(1) A relatively large plexus lies on the auricles in the median plane
immediately beneath the division of the _M. hyoglossus_. It supplies a
network of fibres to the auricles and the adjacent large vessels. It is
said to communicate at various points with the pneumogastric nerve.
(2) A smaller ganglion of oval form, supplies twigs to the neighbouring
vessels and a communicating branch to the hypoglossal nerve
(Wiedersheim).
*e.* Branches to the abdominal viscera; these form intricate plexuses
by which the organs are supplied: the one best known is the solar
plexus (Fig. 131); it is formed chiefly from branches derived from the
third, fourth, and fifth ganglia, and supplies the stomach, etc.; other
plexuses for the various viscera are known by corresponding names, such
are the _Plexus hepaticus_, _renalis_, _genitalis_, _haemorrhoidalis_,
and _vesicalis_.
The sympathetic system is characterised by the fact that the branches
form intricate plexuses, which include numerous ganglia and which are
very irregular; it is also characteristic that most of its fibres are
non-medullated. According to the investigations of Gaskell, the fibres
of the sympathetic system arise in mammalia as very fine medullated
fibres from the posterior vesicular (Clarke’s) columns (Mason has
recently described cells in the frog’s spinal cord, which he holds to
be homologous with the cells of these columns); they leave the cord by
both the ventral and dorsal roots of the spinal nerves, and are thus
connected with two sets of ganglia, (1) with the ganglia of the dorsal
roots, and (2) through the _Rami communicantes_ with the sympathetic
ganglia (vertebral or lateral ganglia); these two sets of ganglia
Gaskell terms proximal. By means of the branches from the sympathetic
ganglia (_Rami efferentes_) part of the fibres pass to another set
of ganglia, the solar plexus, etc., which he terms prevertebral or
collateral; from these the fibres pass to be distributed to the various
viscera and blood-vessels, where a fourth set of very small ganglia
(terminal ganglia) is found. The prevertebral and terminal ganglia
are together classed as distal ganglia. Gaskell holds that the fine
medullated fibres from the cord lose their medullary sheath in one or
other of these ganglia according to the function they fulfil.
The inhibitory fibres of the heart and vaso-dilator fibres of the
blood-vessels continue as white fibres along the vago-sympathetic and
spinal nerves to the distal ganglia (Bidder’s ganglion, etc.), where
the medullary sheath disappears: whereas the ‘augmentor’ fibres of
the heart and vaso-constrictor fibres of the blood-vessels lose their
medullary sheath in the proximal ganglia and pass on as non-medullated
fibres. In the same way the nerve-fibres that bring about contraction
of the circular muscle fibres of the hollow viscera lose their
medullary sheaths in the proximal ganglia, while those fibres, the
influence of which negatives the former, become pale fibres in the
distal ganglia.
Waters has demonstrated that in the frog the various spinal nerves
have each a localised physiological action upon the blood-vessels and
muscular walls of various parts of the alimentary canal: he shows that
The third spinal nerve supplies the oesophagus.
The fourth spinal nerve supplies the stomach.
The fifth spinal nerve supplies the upper third of the small intestine.
The sixth spinal nerve supplies the lower two thirds of the small
intestine.
The seventh spinal nerve supplies the large intestine.
The eighth spinal nerve supplies the bladder, this supply being,
however, not so definite as the others given above.
It has long been known that the branches of the spinal ganglia (ganglia
of the posterior roots) are together larger (one-third, Lenhossék),
and contain more fibres than the ventral and dorsal roots together;
this is supposed to be in part due to an acquisition of new fibres
derived from the ganglia. The majority of recent observers hold that
each ganglionic cell has only one process, which, however, soon
bifurcates; whether any of the fibres so formed pass as far as the cord
or beyond its blood-vessels is doubted by most observers, and denied by
Gaskell. These remarks and the description of the cells of the spinal
ganglia (p. 176) hold good for the lateral or vertebral ganglia and the
prevertebral ganglia (solar ganglion, etc.) of the sympathetic system;
the terminal ganglia will be described with the organs in which they
are found.
H. HISTOLOGICAL NOTES ON THE NERVOUS SYSTEM.
(In order to render the foregoing description of the nervous
system more complete, the following notes have been added by the
translator.)
[The histological elements of the nervous system are nerve-cells
and nerve-fibres; of these the nerve-cells have been described with
the parts in which they occur; it may simply be remarked that later
observers have been unable to discover the ‘spiral cells’ described by
Beale, Arnold, and others. The nerve-fibres, as in most other animals,
are of two kinds, medullated and non-medullated.
*1.* Medullated nerve-fibres or white fibres are found in all cranial
and spinal nerves, with the exception of the olfactory nerves, and in
many of the sympathetic nerves (see Sympathetic System); also in the
white matter of the brain and spinal cord; examined microscopically
the fibres are seen to consist of an external sheath or neurilemma, a
medullary sheath, and an axis-cylinder:--
*a.* The neurilemma (Sheath of Schwann, Outer or Primitive Sheath) is a
nucleated endothelial layer covering the nerve-fibre; it is continuous
with the corresponding coat of the nerve-cells, and is uninterrupted
throughout the length of the nerve; at the nodes, however, it dips down
towards the axis-cylinder, the circular groove so formed being filled
with cement substance.
*b.* The medullary sheath (White substance of Schwann); the presence of
this sheath is the chief cause of the whiteness of these nerves; the
thickness of the sheath varies considerably, and towards the ultimate
distribution of the nerve it is entirely lost. At more or less regular
intervals along the course of the nerve-fibre the continuity of the
medullary sheath is broken, and gives the fibres the appearance of
being constricted at these places; such constrictions are known as
nodes of Ranvier; the portion between two such nodes being termed
an internode. Each internode possesses an oval, flattened, granular
nucleus at about its middle and placed between the neurilemma and the
medullary sheath; the nucleus has a nucleolus. In the fresh state the
medullary sheath seems to be fluid; it is of a fatty nature.
Medullary segments are caused by breaks in the continuity of the
medullary sheath, which are seen only in nerves which are no longer in
their normal condition, and are especially well marked after treatment
with osmic acid. The breaks are oblique; hence the conical end of one
segment fits into the funnel-shaped end of the next. How far they
correspond to pre-existent structures is uncertain. The segments in the
frog vary in length from 0.010 to 0.040 mm.
*c.* The axis-cylinder is the essential part of every nerve-fibre;
it shows a longitudinal striation corresponding to the fine fibrils
(primitive fibrillae) of which it consists; these fibrils often exhibit
minute varicosities: at times it has the appearance of being invested
with a very delicate structureless sheath. It is continuous through the
nodes of Ranvier.
*2.* Non-medullated nerve-fibres (Grey or Varicose Fibres; Fibres of
Remak); these occur chiefly in branches and plexuses of the sympathetic
system; they consist of a neurilemma and an axis-cylinder, which agree
exactly with the corresponding elements found in the medullated fibres.
The nerve-fibres, whether medullated or non-medullated, are bound
together by connective-tissue to form nerves. A number of fibres bound
together by connective-tissue to form a slender cord is known as a
funiculus; a small nerve may consist of one such funiculus; the sheath
surrounding it is known as the perineurium, and sends in supporting
processes between the fibres (endoneurium): when several funiculi are
bound together to form a large nerve the common sheath is known as
the epineurium. These sheaths support nerves (_nervi nervorum_) and
vessels (_vasa vasorum_) supplying the nervous elements, and their
intercellular spaces form lymph-canals. The whole nerve is surrounded
by an endothelial coat, which helps to form a lymph-space, which more
or less completely surrounds the nerve.
The ultimate distribution of the nerve-fibres will be included in the
description of the various organs in which they end.]
SECTION IV.
THE VASCULAR SYSTEM.
THE VASCULAR SYSTEM.
LITERATURE.
THE HEART AND BLOOD-VESSELS.
*Aeby*, Ueber den feineren Bau der Blutcapillaren. Centralbl. f. d.
med. Wiss. 1865, p. 209.
*Altmann, R.*, Ueber Corrosion in der Histologie. Centralbl. f. d.
med. Wiss. 1878, p. 245.
*Aubert, H.*, Die Innervation der Kreislaufsorgane. Hermann’s
Handbuch der Physiologie. Leipzig, 1880. Vol. VI, Pt. I, p. 377.
*Beck, K.*, Zur Kenntniss der Herznerven. Arch. f. mik. Anat. 1884.
Vol. XXIV, pp. 11–19.
*v. Bezold*, Untersuchungen über die Innervation des Herzens.
Leipzig, 1863.
*Bidder, F.*, Ueber functionell verschiedene und räumlich getrennte
Nervencentra im Froschherzen. Arch. f. Anat. u. Physiol. 1852,
p. 163.
*Bidder, F.*, Zur näheren Kenntniss des Froschherzens und seiner
Nerven. Arch. f. Anat. u. Physiol. 1866, p. 1.
*Bidder, F.*, Endigungsweise der Herzzweige des N. vagus beim
Frosche. Arch. f. Anat. u. Physiol. 1868, p. 1.
*Bidder, F.*, and *Gregory*, Beiträge zur Physiologie der
Herzbewegung beim Frosche. Dorpat, 1865.
*Boas, J. E. V.*, Ueber den Conus arteriosus und die Arterienbogen
der Amphibien. Morph. Jahrb. 1881. Vol. VII, pp. 271–273.
*Boas, J. E. V.*, Beiträge zur Angiologie der Amphibien. Morph.
Jahrb. 1882. Vol. VIII, pp. 169–187.
*Bobretzky, C.*, Ueber die Entwickelung der Capillargefässe.
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*Bremer, L.*, Die Nerven der Capillaren der kleinen Arterien und
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blood-corpuscle. Quart. Journ. Micros. Sci. 1864, pp. 32–43.
*Bizzozero, G.*, Ueber die Teilung der roten Blutkörperchen.
Centralbl. f. d. med. Wiss. 1881, p. 129.
*Bizzozero, G.*, Ueber die Teilung der roten Blutkörperchen.
Centralbl. f. d. med. Wiss. 1882, p. 577.
*Bizzozero, G.*, and *Torre, A. A.*, Ueber die Entstehung der roten
Blutkörperchen bei den verschiedenen Wirbelthierklassen. Virchow’s
Arch. 1884. Vol. XCV, pp. 1–25.
*Brücke, E.*, Ueber den Bau der rothen Blutkörperchen. Wiener
Sitzungsb. 1867. Vol. LVI, Pt. II, pp. 79–91.
*Donders* and *Moleschott*, Holländische Beiträge. 1848, p. 361.
*Eberth, C. J.*, Ueber die Vermehrung der rothen Blutkörperchen nach
Untersuchungen von W. Aly. Fortschritte d. Med. 1885. Vol. III,
pp. 1–7.
*Fuchs, E.*, Beitrag zur Kenntniss des Froschblutes und der
Froschlymphe. Virchow’s Arch. 1877. Vol. LXXI, p. 78.
*Gaule, J.*, Beobachtungen der farblosen Elemente des Froschblutes.
Arch. f. Anat. u. Physiol. 1880, pp. 375–392.
*Gulliver, G.*, Measurements of the red blood-corpuscles of
Batrachians. Proc. Zool. Soc. London, 1873, p. 162.
*Hewson, W.*, On the figure and composition of the red Particles
of the Blood, commonly called Globules. Phil. Trans. 1773.
Vol. LXIII, Pt. I, p. 303.
*Home, E.*, On the changes the blood undergoes in the act of
coagulation. Phil. Trans. 1818, p. 172.
*Kollmann, J.*, Bau der rothen Blutkörperchen. Zeitschr. f. wiss.
Zool. 1874. Vol. XXIII, p. 462.
*Kusnezoff, F.*, Ueber blutkörperhaltige Zellen der Milz. Wiener
Sitzungsb. 1873. Vol. LXVII, Pt. III, pp. 58–67.
*Moriggia, A.*, Ueber den Durchtritt der farblosen Blutkörperchen
durch die Blutgefässwandungen, etc. Moleschott’s Untersuchungen.
1876. Vol. XI, p. 470.
*Neumann, E.*, Zur Histologie der rothen Blutkörperchen. Centralbl.
f. d. med. Wiss. 1865, p. 481.
*Owsjannikow, P.*, Zur Histologie der Blutkörperchen. Bullet. de
l’acad. science de Pétersbourg. 1865. Vol. VIII, pp. 561–572.
*Peremeschko*, Ueber die Theilung der rothen Blutkörperchen bei
Amphibien. Centralbl. f. d. med. Wiss. 1879, pp. 673–675.
*Ranvier, L.*, Traité technique d’histologie, pp. 148–224.
*Rollett, A.*, Versuche und Beobachtungen am Blute. Wiener Sitzungsb.
Vol. XLVI, Pt. II, pp. 65–98.
*Stricker*, Beobachtungen über die Entstehung des Zellkernes. Wiener
Sitzungsb. 1878. Vol. LXXVI, Pt. III, p. 7.
*Thoma, R.*, Die Ueberwanderung farbloser Blutkörperchen von dem Blut
in das Lymphgefässsystem. Heidelberg, 1873.
*Welcker, H.*, Grösse, Zahl, Volum, Oberfläche und Farbe der
Blutkörperchen bei Menschen und Thieren. Henle u. Pfeuffer’s
Zeitschr. 1864. Vol. XX, pp. 258–307.
PART 1.
THE HEART AND BLOOD-VESSELS.
I. THE HEART.
(The original arrangement of this section has been modified.)
The heart is situated in the middle line above the central portion of
the shoulder-girdle and _M. sternohyoideus_, and below the oesophagus;
the apex is directed backwards and lies between the lobes of the liver,
the base is directed forwards and lies a short distance behind the
larynx. The heart is surrounded by the pericardium.
A. The *Pericardium* [is a very thin membranous sac, which completely
encloses the heart; it is attached, at some distance, to the large
vessels passing to and from the heart, and has inserted into it some
fibres of the _M. obliquus abdominis internus_ (see page 70). A fold
of the pericardium extends from the dorsal surface to the truncus
arteriosus, and through it courses the vena cardiaca.
[Illustration: Fig. 132.
The heart and blood-vessels, seen from the ventral surface; after Howes.
_AC._ Left anterior caval vein.
_C′._ Carotid arch.
_LA._ Left auricle.
_P′._ Right pulmo-cutaneous arch.
_RA._ Right auricle.
_S′._ Left systemic arch.
_TA._ Truncus arteriosus.
_V._ Ventricle.
]
The pericardium is a connective-tissue membrane, and is lined on
either side with endothelium, which is in part ciliated (Leydig); the
endothelium of the inner surface is continued on to the heart and so
forms a closed lymph-sac. The pericardium is more or less pigmented,
and contains both vessels and nerves; it may contain fat-cells].
B. The *Heart*.
[The heart is a hollow muscular organ, composed of: (1) two auricles,
forming the wider anterior portion; (2) the ventricle, placed
behind the auricles; (3) the sinus venosus, situated dorsally; and
(4) the truncus arteriosus, lying ventrally. Examined while still
living, the auricles are seen to be much darker in colour than the
ventricle, due to the blood being seen through their thinner walls;
between the auricles and the ventricle is a distinct groove, the
auriculo-ventricular groove. The whole organ is more or less pigmented,
especially the ventricle (_R. temporaria_ has much less pigment).]
[Illustration: Fig. 133.
The heart, seen from above, and dissected to show the opening from the
Sinus venosus to the right auricle; after Howes.
_C′._ Right carotid arch.
_IC._ Posterior caval vein.
_LA._ Left auricle.
_P′._ Right pulmo-cutaneous arch.
_PV._ Pulmonary vein.
_RA._ Right auricle.
_S′._ Right systemic arch.
_SV._ Sinus venosus.
_SV′._ Opening of Sinus venosus into the right auricle.
_V._ Right anterior caval vein.
]
*a.* The *Sinus venosus* (_Sinus venarum cavarum_), (Fig. 133 _SV._)
is a thin-walled sac lying on the dorsal surface of the heart, and
very slightly to the right side (Hoffmann). It is somewhat triangular
in form, receiving an anterior caval vein at each anterior angle
(_V._), and the posterior caval vein (_IC._) at the posterior angle.
The ventral wall has a transverse opening (_SV′._), by which it
communicates with the right auricle; the opening possesses two valves,
an anterior and a posterior, and is placed close to the auricular
septum.
*b.* The *auricles* [are not always separated, as the septum which
usually brings about the separation is in some cases incomplete, and in
rare instances appears to be absent (Hoffmann)]; according to Ecker,
the auricular septum is sometimes placed so far to the left side
that it appears to be absent (Fig. 135). The septum is attached to
the walls of the auricles so as to form two distinct cavities, which
communicate at the auriculo-ventricular opening, where the septum has
a free concave border (Fig. 134). The right auricle is much larger
than the left, and receives the systemic venous blood from the sinus
venosus by the opening (Figs. 133 and 134 _SV._) already described.
The left auricle receives the blood from the lungs by the pulmonary
vein (Fig. 133 _PV._), which opens into the auricle near the septum
(Fig. 134 _PV._): [the openings from the sinus venosus and from the
pulmonary vein may be so closely approximated as to be separated by the
septum only. The septum is much thinner than the auricular walls]. Both
auricles open into the ventricle by the auriculo-ventricular opening
(Fig. 134).
[Illustration: Fig. 134.
The frog’s heart seen from the ventral surface, and dissected so as to
show its structure. The ventral walls of the truncus arteriosus and of
the auricles and ventricle have been removed. From a drawing by Mr.
Hurst.
_A._ Auriculo-ventricular aperture and valve.
_B._ Aperture leading from ventricle to truncus arteriosus.
_C._ Left carotid arch.
_LA._ Left auricle.
_P._ Left pulmo-cutaneous arch.
_P′._ Style passed down right pulmo-cutaneous arch into the
truncus arteriosus, _T._
_PV._ Opening of pulmonary vein.
_RA._ Right auricle.
_S._ Left systemic arch.
_SA._ Septum atriorum.
_SV._ Opening of Sinus venosus into right auricle.
_V._ Ventricle.
]
*c.* The *ventricle* (Figs. 132, 134, and 136 _V._), examined while
still living, is seen to be bluntly conical in shape and darker on the
left side than on the right; this is due to the ventricular wall of the
right side, near the truncus arteriosus, being somewhat thinner. The
inner wall is not smooth but possesses muscular ridges (_Trabeculae_).
At its base the ventricle communicates with the auricles by the
auriculo-ventricular opening (Figs. 134 and 136), and with the truncus
arteriosus by a separate opening (Fig. 134 _A._). The ventricle is
lined by a layer of endocardial endothelium.
[Illustration: Fig. 135.
Dissection of a case in which the auricular septum is placed more to
the left than is normal.
_S_ Septum.
_SS_ Left auricle.
_V_ Opening into the Sinus venosus.
]
[Illustration: Fig. 136.
Dissection of the heart from the left side; after Howes.
_A._ Auriculo-ventricular opening.
_AC._ Anterior caval veins.
_IC._ Posterior caval vein.
_LA._ Left auricle.
_PV._ Pulmonary vein.
_RA._ Right auricle.
_SV._ Sinus venosus.
_TA._ Truncus arteriosus.
_V._ Ventricle.
]
The *auriculo-ventricular opening* (Fig. 134 _A._) is a large aperture
guarded by two valves, a dorsal and a ventral: each valve is formed
by a reduplication of the endothelium, and contains a small amount of
connective-tissue; its free margin is bound down by a number (about
twelve) of fibrous cords, the _chordae tendineae_, which are attached
by their posterior extremities to the trabeculae.
*d.* The *truncus arteriosus* (Figs. 132 _TA._, 134 _A._) arises at the
base of the ventricle, on the right side of its ventral surface, then
passes forwards and to the left, across the auricles, to reach their
anterior border near the median line, where it divides to form two
vessels.
Internally it is incompletely divided into two compartments by a spiral
valve (Fig. 134); the valve is attached to the dorsal surface and is
free ventrally: when the vessel is fully dilated (artificially), the
valve extends two-thirds of its diameter. The opening of the vessel
into the ventricle is guarded by two semilunar valves (Fig. 134 _A._),
the free margins of which are bound to the inner surface of the tube by
_chordae tendineae_. The distal extremity has a semi-lunar valve in the
left compartment (Fig. 134), which is attached by a delicate band to
the spiral valve (Ecker).
C. *The minute structure of the Heart.*
[The heart consists chiefly of muscle, but possesses also nerve-fibres,
nerve-cells, endothelium, and connective-tissue; the truncus arteriosus
has, in addition, blood-vessels.
*a.* The *muscular structure* of the heart.
(1) The *arrangement* of the *muscle-fibres* varies in the different
portions of the heart. That of the ventricle will be easily understood
by reference to Fig. 137. A layer of circular fibres (_CM_) extends
round the whole ventricle, and from it more or less radial or
transverse bands (_TM_, also Fig. 138 _TM_) pass inwards; these, in the
apical portion of the ventricle, seem to extend almost transversely
across; towards the base they are directed onwards and forwards towards
the auricles. Of these bands some, near the apex, can be traced
directly to the opposite side, others join the wall more anteriorly,
and still others join bands of muscular fibres (_LM_), which may be
described as longitudinal, and form the _Musculi papillares_. In the
anterior portion of the ventricle the same arrangement holds good, but
is modified to form a central cavity; still more anteriorly, at the
junction of auricles and ventricle, the trabecular structure is much
less apparent, the fibres being closer and mainly circular.
[Illustration: Fig. 137.
I. Transverse section through the junction of the hinder and middle
thirds of the ventricle of _R. temporaria_. II. Transverse section
through junction of middle and anterior thirds of the same heart. Occ.
I, Syst. 1, Leitz. The heart was freely distended[62] with dilute
spirit, and so hardened.--G. H.
_CC_ Central cavity.
_CM_ Circular muscle.
_LM_ Longitudinal muscle.
_TM_ Transverse muscle.
]
[Footnote 62: The base of the ventricle measured, when distended, 8 mm.
by 5 mm.]
In the auricles the muscular fibres are chiefly arranged in circular
rings which cross one another; on the inner surface, however, traces
of an arrangement similar to that in the ventricle may be made out. In
the heart, from which the sections in Fig. 137 were drawn, transverse
bands (cut longitudinally), 0.33 mm. in length, were numerous; their
central ends terminated in bands, the fibres of which were cut
transversely. The auricular septum (Fig. 141 a _M_) also possesses
muscular fibres which cross one another in its substance.
The fibres of the truncus arteriosus resemble those of an ordinary
artery; those of the sinus venosus are arranged in rings, mostly
transverse, but others oblique, and a few longitudinal.]
(2) The *structure* of the *cardiac muscle-fibres* (Figs. 138 and 141
a).
[The cardiac muscle of the frog consists of spindle-shaped cells, which
as Pohl-Pincus pointed out, are of two kinds; the main difference
between the two being in the size of the nucleus, which is much broader
in one than in the other.
[Illustration: Fig. 138.
Portion of a transverse section through the middle of the ventricle of
_R. temporaria_. From same heart as the sections in Fig. 136. Oc. I.
Syst. 7, Leitz.--G. H.
_A_ Rod-shaped nuclei of muscle fibre.
_B_ Oval nuclei of muscle fibre.
_CM_ Circular layer of muscle.
_CT_ Connective-tissue.
_E_ Endothelium of the epicardium.
_TM_ Transverse bands of muscle.
]
α. Cells with a broad nucleus (Fig. 138 _B_): the nucleus is lenticular
or egg-shaped, 4 to 7 µ broad, 8 to 14 or 18 µ long; the ratio of
length to breadth being 1 : 2.
β. Cells with a narrow nucleus (Fig. 138 _A_): the nucleus is
rod-shaped, 2·5 to 3·5 µ broad and 25 to 43 µ in length. The ratio
of length to breadth varying from 1 : 8 to 1 : 16. These cells are
more frequent in the right half of the base of the ventricle than the
former variety. In the trabeculae the second variety is more numerous
(Pohl-Pincus).
The muscle-fibre may be simple (Fig. 141 a _M_) or possess branches
(Fig. 138); the fibres are all more or less spindle-shaped, and
striated transversely and longitudinally, but possess no sarcolemma.
The protoplasmic contents of the cell are finely granular; the nucleus
much more coarsely granular and possessing one or more distinctly
marked nucleoli. The striations are due to the presence of a network,
which has been carefully described by Messrs. B. Melland and C. F.
Marshall[63], and is similar to that of ordinary voluntary muscle (see
histology of muscle).]
[Footnote 63: I have had opportunity of examining Mr. Marshall’s slides
and have convinced myself of the correctness of his observations.]
*b.* The *nerves* of the *heart*.
The nervous supply of the heart is derived from the sympathetic system
and from the cardiac branches of the pneumogastric nerve; the course of
which has already been traced (page 175) to the roots of the anterior
caval veins, where they form a simple plexus by means of a connecting
link (Fig. 139). The plexus possesses nerve-cells and sends off two
nerves into the auricular septum; the one (_d_) lies dorsally and is
shorter and thicker than the other (_v_), which lies ventrally in the
septum. They course backwards to the posterior border of the septum,
and there distribute fine branches to the base of the ventricle and
surrounding parts.
[Illustration: Fig. 139.
Course of the cardiac nerves in the auricular septum.
_d_ Dorsal nerve.
_v_ Ventral nerve.
]
[In the whole of their course in the heart they have numerous
nerve-cells, either imbedded between their fibres or attached to the
nerves and their branches.
The nerve-fibres are both medullated and non-medullated. The
nerve-cells (Figs. 139, 140, 141) are usually oval, and are unipolar
or rarely bipolar; sometimes two cells exist in the same envelope,
forming the ‘twin-cells’ of Dogiel (Fig. 141 b II). According to the
recent observations of Lavdowsky and Dogiel each cell receives one
medullated fibre and gives off a fine non-medullated fibre; the two run
together for a short distance, after which the non-medullated fibre
separates to supply muscle-fibres.
[Illustration: Fig. 140.
Group of nerve-cells on the cardiac nerve, from the auricular septum.
Stained with picrocarmine. Occ. III, Syst. 3, Hartnack; after Dogiel.
_F_ Fibres of the cardiac nerve.
_G_ Nerve-cells.
]
Two large clusters of nerve-cells have received special names.
*Remak’s ganglion* is a large group of nerve-cells in the wall of the
sinus venosus.
*Bidder’s ganglion* is formed, collectively, by groups of cells in the
auriculo-ventricular groove, the chief groups being attached to the two
cardiac nerves.
No nerve-cells have been discovered behind that portion of the
ventricle near the auriculo-ventricular groove, nor has a direct
connection between the cells or their processes with the fibres of the
pneumogastric nerve been made out.
Nerve-fibres have been described as existing in all parts of the
ventricle and being connected with the muscle-fibres (Openchowsky and
others); this cannot, as yet, be accepted as proved.
The truncus arteriosus also possesses nerve-fibres and nerve-cells
(Pagliani, Löwit, and others), but their arrangement seems to be very
irregular. Löwit did not succeed in finding the nerve-cells in all
cases examined; and Engelmann denies their occurrence.]
*c* and *d*. [The *endothelium* and *connective-tissue* of the heart.
The connective-tissue of the heart exists only in very small quantity.
A fine layer on the outer surface of the ventricle, especially towards
the auriculo-ventricular groove, can easily be seen (Fig. 138 _CT_);
the various valves, the auricular septum, and more particularly the
truncus arteriosus, all contain connective-tissue. In the latter part
the spiral valve is wholly formed of this tissue.
[Illustration: Fig. 141 a.
Small group of nerve-cells from the auricular septum. Stained with
picrocarmine and silver nitrate, after Dogiel.
_E_ Endothelium (endocardium).
_G_ Nerve-cells.
_M_ Muscle-fibres.
_N_ Nucleus.
_N_′ Nucleolus.
]
[Illustration: Fig. 141 b.
Isolated nerve-cells from frog’s heart. I. Usual form of nerve-cell.
II. ‘Twin-cell.’
_C_ Capsule.
_N_ Nucleus.
_N_′ Nucleolus.
_P_ Process.
]
The whole of the inner surface is lined with endothelium
(endocardium), which covers the various trabeculae; the external
surface of the heart is likewise covered with an epicardial layer of
endothelium (Fig. 138 _E_).]
[Illustration: Fig. 142.
Arteries and veins of the Truncus arteriosus of Bufo vulgaris, after
Hyrtl.
_a_ Arteria bulbi.
_b_ Truncus arteriosus.
_h_, _i_ Hepatic portal veins.
_t_ Right and left synangium.
_v_ Vena bulbi anterior.
_vi_ Left innominate vein.
_vc_ Vena bulbi posterior (V. cardiaca).
_A_ Right auricle.
_A_′ Left auricle.
_V_ Ventricle.
]
*e.* The blood-supply to the heart.
With the exception of the _truncus arteriosus_, no part of the heart
possesses blood-vessels (Hyrtl). [The _truncus arteriosus_ (Fig. 142
_b_) has a rich anastomosis, which receives its blood by the _arteria
bulbi_ (_a_), a branch of the carotid arch. Two veins connect this
anastomosis with the systemic veins, and with the hepatic portal veins:
the former, _vena bulbi anterior_ (_v_), passes over the auricles to
open into the left innominate vein (_vi_); the latter, the _vena bulbi
posterior_ (_vc_) or _vena cardiaca_, as it is more usually named,
passes from the _truncus arteriosus_ in a fold of pericardium, and then
courses backwards to open into the anterior-abdominal vein.]
II. THE ARTERIES.
(The original arrangement of this section has been modified.)
The _Truncus arteriosus_ divides to form two vessels (Figs. 132, 134);
each of these is divided by two partitions into three compartments,
which after a short course together separate to form three distinct
vessels, the carotid, systemic, and pulmo-cutaneous arches.
*1.* The *carotid arch* (_Canalis carotico-lingualis_, Brücke; _Ductus
caroticus_), (Fig. 143 _I_) is the most anterior of the three arches:
it winds round the side of the oesophagus as far as the carotid gland,
where it divides to form two branches; the right carotid arch gives off
a small branch to the _Truncus arteriosus_, the _Arteria bulbi_ (see
above).
[Illustration: Fig. 143.
Schema of the arterial system of Rana esculenta.
_A_ Dorsal aorta.
_c_ Cutaneous artery.
_ca_ Carotid artery.
_d_ Carotid gland.
_ic_ Iliac arteries.
_ie_ External iliac artery.
_ii_ Internal iliac artery.
_J_ Mesenteric artery.
_l_ Lingual artery.
_o_ Occipital artery.
_ov_ Occipito-vertebral artery.
_P_ Pulmonary artery.
_s_ Subclavian artery.
_T_ Truncus arteriosus.
_ug_ Urinogenital arteries.
_v_ Vertebral artery.
_I_ Carotid arch.
_II_ Systemic arch.
_III_ Pulmo-cutaneus arch.
]
The *carotid gland* (Fig. 144 _c_′) is a dilated portion of the vessel.
The interior contains bands or trabeculae of muscle, which give its
walls a more or less spongy structure; the muscle-fibres are not
transversely striated (Hoffmann).
*a.* The *lingual artery* (_Arteria lingualis_, _Arteria
hyoidea-lingualis_, _Arteria hyoidea_), (Figs. 143 _l_, 144 _L_) arises
by two roots from the inner surface of the carotid gland, and courses
forwards and inwards, supplying branches to the thyroid gland and the
_Musculi geniohyoidei_, to the ventral surface of the hyoid; another
continues forwards on the outer border of the _M. hyoglossus_ to supply
branches to the hyoid and tongue.
*b.* The *carotid artery* (_Arteria carotis communis_), (Figs. 143
_ca_, 144 _c_″) arises by several roots from the outer wall of the
carotid gland; and passes over the _Musculus petrohyoideus I_ to the
anterior end of the oesophagus, round which it courses towards the
vertebral column, and then runs forwards to the base of the skull.
The artery then courses forwards, lying immediately above the mucous
membrane and underneath the transverse arm of the parasphenoid, which
it crosses about midway between its back and external end; [at this
point the artery gives off two palatine arteries, then ascends in the
orbit to the origin of the _M. pterygoideus_, and divides into two
branches, the internal carotid artery and the ophthalmic artery]. The
branches are:--
(1) The pharyngeal artery (_Arteria pharyngea ascendens_), (Fig. 145
_p_) which runs towards the opening of the Eustachian tube,
distributes branches to the pharynx, and anastomoses with the _Arteria
pharyngeo-maxillaris_ of the cutaneous artery, and with the _Ramus
inframaxillaris_ of the occipital artery.
[Illustration: Fig. 144.
Right carotid gland.
_c_ Carotid arch.
_c_′ Carotid gland.
_c_″ Carotid artery.
_L_ Lingual artery.
]
(2) [The posterior palatine artery (_Arteria palatina posterior_,
Virchow) immediately divides into a number of small twigs to supply the
mucous membrane of the hinder and outer parts of the gums.]
(3) The anterior palatine artery (_Arteria palatina anterior_, Virchow;
_Arteria palatina_, Ecker), (Fig. 145 _p_′) runs forwards, between
the _Musc. levator bulbi_ and the mucous membrane, with the _Ramus
palatinus_ of the trigeminal nerve. [On reaching the palatine bone,
it curves outwards to the outer anterior angle of the orbit, where it
gives off a branch backwards along the upper jaw to the hinder portion
of the orbit.] In its course it supplies twigs to the surrounding
tissues, but chiefly to the mucous membrane and Harder’s gland.
[Illustration: Fig 145.
Arterial system of _Rana esculenta_.
_A_ Dorsal aorta.
_Ad_ Right systemic arch.
_As_ Left systemic arch.
_c_ (opposite fore-limb) Carotid artery.
_c_ (in abdomen) Coeliac artery.
_cm_ Cutaneous artery.
_e_ Lingual artery.
_H_ Heart.
_H_′ Harderian gland.
_L_ Liver.
_Lu_ Lung.
_m_ Mesenteric artery.
_M_ Stomach.
_M_′ Spleen.
_o_ Ophthalmic artery.
_p_ Pharyngeal artery.
_p_′ Anterior palatine artery.
_S_ Subclavian artery.
_I_ Carotid arch.
_II_ Systemic arch.
_III_ Pulmo-cutaneous arch.
]
(4) The internal carotid artery (_Art. cerebralis_, Virchow); see
Arteries of Brain, p. 162.
(5) The ophthalmic artery (_Art. ophthalmica_), (Fig. 145 _o_) [is
larger than the internal carotid artery at this point; it crosses the
origins of the _M. rectus externus_ and of the _M. retrahens bulbi_
and reaches the optic nerve; the artery then runs forwards along the
under surface of this nerve and of the eyeball, lying close to the
sclerotic coat as far as a little beyond the equator, where it pierces
the sclerotic coat so obliquely that the choroid coat is only reached
at the ciliary processes. In its course the artery supplies:--
α. Muscular branches, given off at the point where the artery reaches
the eyeball.
β. Two arteries (_AA. ciliares_) to the choroid, given off at the same
point as the foregoing.
γ. Two arteries to the iris.
δ. The _Art. hyaloidea_, the terminal portion of the ophthalmic artery.
(For further description of these vessels, see Eye.)].
*2.* The *systemic arch* (_Ductus aorticus_), (Figs. 132, 143, and 145
_II_) is the middle arch of the three; it arises from the middle canal
of the _Ductus arteriosus_, and winds obliquely round the oesophagus
between the _MM. petrohyoidei I_ and _II_ towards the vertebral
column, which it reaches at about the level of the sixth vertebra. The
right systemic arch is continued as the dorsal aorta, the left arch
communicates with it merely by a small opening, and is then continued
as the coeliaco-mesenteric artery.
Branches of the systemic arch:--
*a.* The *laryngeal artery* (_Arteria laryngea_), (Fig. 146 _lg_)
arises from the inner border of the systemic arch before it reaches the
oesophagus; it passes forwards and inwards to be distributed in the
larynx and pharynx. According to Brücke this artery possesses a valve
at its point of origin.
[Illustration: Fig. 146.
Transverse section at level of the larynx.
_C_ Carotid gland.
_G_ Glottis.
_lg_ Laryngeal artery.
_S_ Subclavian artery.
_I_ Carotid arch.
_II_ Aortic arch.
]
*b.* The *oesophageal arteries* (_Arteriae oesophageae_) pass from the
upper part of the arch to the dorsal surface of the oesophagus.
*c.* The *occipito-vertebral artery* (Ecker), (_Art.
occipito-vertebralis_), (Fig. 147 _o_, _v_) [arises from the systemic
arch immediately in front of the transverse process of the second
vertebra, and ascends immediately in contact with the body of the first
vertebra, which it separates from the _MM. intertransversarii capitis_
and the sympathetic cord]. Immediately under the most anterior portion
of the _M. longissimus dorsi_ the artery divides into two branches, the
vertebral and occipital arteries:--
(1) The *vertebral artery* (_Arteria vertebralis_ or
_supra-vertebralis_) (Fig. 147 _v_) courses backwards lying
on the transverse processes of the vertebrae and on the _MM.
intertransversarii_, under cover of the _M. longissimus dorsi_. In this
course it is close to the oblique processes, and may even be partially
covered by these; it extends beyond the sacrum, and gives off:--
α. The _Rami spinales_, which pass through the intervertebral foramina
to the spinal cord (see Arteries of Spinal Cord, p. 162).
[Illustration: Fig. 147.
Dissection to show the occipito-vertebral and the cutaneous arteries.
The skin of the back has been divided by a median incision and drawn to
either side; the right arm dislocated and removed through the opening
in the skin (at _A_). On the left side the extensor muscles of the back
have been removed.
_c.m._ Cutaneous artery.
_c.p._ Arteria cutanea pectoris.
_o_ Occipital artery.
_s_ Scapular artery.
_v_ Vertebral artery.
]
β. The _Rami dorsales_; these supply the muscles of the back and send
branches to the skin, which accompany the cutaneous branches of the
spinal nerves through the _Saccus lymphaticus cranio-dorsalis_.
γ. The _Rami intercostales_ are distributed in part to the _MM.
intertransversarii_; other twigs pass ventrally to the periganglionic
glands; the longest branches accompany the anterior divisions of the
spinal nerves to the muscles and skin of the belly (Fig. 145).
(2) The *occipital artery* (_Arteria occipitalis_), (Figs. 147 and 148
_o_), the anterior branch of the occipito-vertebral artery, pierces
the _M. longissimus dorsi_; then courses forwards under cover of the
_Fascia dorsalis_ and upon the _M. temporalis_, and divides, behind the
eyeball [at the anterior border of the _M. temporalis_, Virchow], into
two branches:--
α. The _Ramus orbito-nasalis_ (Fig. 148 _on_) accompanies the
ophthalmic nerve along the wall of the cranium, and passes through the
sphenethmoid, with the nasal branch of the ophthalmic nerve, to the
nose, where it divides into two branches supplying the mucous membrane
of the nose. In its course through the orbit the artery supplies
branches to the Harderian gland and neighbouring parts, and anastomoses
with the ascending branch of the _Arteria palatina_.
β. The _Ramus maxillaris communis_ (_Art. temporalis_, Virchow),
(Fig. 148 _m_) runs downwards and outwards along the anterior border of
the _M. temporalis_, and passes under the anterior arm of the squamosal
bone to course backwards on the upper jaw. At this point the _Ramus
maxillaris superior_ (_m_′) is given off. The main artery continues its
backward course to the tympanic membrane, where it divides into its
three terminal branches:--
[Illustration: Fig. 148.
Branches of the occipito-vertebral and cutaneous arteries in the head;
side view. The skin (_H_) has been reflected downwards.
_c.m._ Cutaneous artery.
_l.a._ M. levator scapulae.
_m_ Art. maxillaris communis.
_m_′ Art. maxillaris superior.
_m_″ Art. maxillaris inferior.
_o_ Occipital artery.
_on_ Art. orbito-nasalis.
_p.m._ Art. pharyngo-maxillaris.
_v_ Vertebral artery.
]
[(1) The _Ramus maxillaris superior_ (_AA. maxillares superiores_,
Virchow), usually not a single artery but a number of small twigs,
which supply the space between the eye and the upper jaw.
(2) A small ascending branch to the tympanic membrane (Virchow).
(3) A _Ramus auricularis_ (Virchow), which forms a rich anastomosis
on the hinder wall of the tympanic cavity, and supplies a twig to the
tympanic membrane. This passes from the upper border of the membrane
to the point of attachment of the _Columella auris_ (extrastapedial),
round which it forms a circular anastomosis. The _Ramus auricularis_
also anastomoses with the cutaneous artery.
[Illustration: Fig. 149.
Dissection to show the occipito-vertebral and the cutaneous arteries.
The skin of the back has been divided by a median incision and drawn to
either side; the right arm dislocated and removed through the opening
in the skin (at _A_). On the left side the extensor muscles of the back
have been removed.
_c.m._ Cutaneous artery.
_c.p._ Arteria cutanea pectoris.
_o_ Occipital artery.
_s_ Scapular artery.
_v_ Vertebral artery.
]
(4) A branch passing inwards to the fat-body, and lying immediately in
front of the deltoid muscle (Virchow).
(5) A small branch running on to the inner surface of the angle of the
jaw and then forwards (Virchow).
(6) A larger vessel, the _Ramus maxillaris inferior_ (Fig. 148 _m_″),
which arises from the _Ramus maxillaris superior_ under cover of the
tympanic membrane, and accompanies the _Ramus mandibularis_ of the
trigeminal nerve through the _M. masseter_, or between this muscle and
the _M. temporalis_ to the mandible, and then courses forwards to the
chin. A large cutaneous branch is given off half-way along the floor
of the mouth. The artery gives off many small twigs to supply the
neighbouring structures.]
3. The *pulmo-cutaneous arch* (_Ductus pulmo-cutaneus_), (Figs. 132
143, and 145 _III_) is the hindmost (fifth embryonic) of the three
persistent arches; it passes upwards and forwards on the oesophagus,
and at the level of the carotid gland divides into two branches, the
pulmonary artery and the cutaneous artery.
a. The *pulmonary artery* (_Arteria pulmonalis_) runs backwards to the
root of the lung, along the outer surface of which it is continued in a
sinuous course. It supplies the lung.
b. The *cutaneous artery* (_Arteria cutanea magna_), (Fig. 149
_c.m._) [passes along the deeper surface of the _M. petrohyoideus
III_ until near the prootic bone; in this course it travels forwards,
outwards, and upwards, crosses the outer border of the muscles,
and appears between the _M. levator anguli scapulae_ and the _M.
sternocleidomastoideus_. At this point the artery curves sharply round
to reach the angle of the jaw, the hinder border of the _M. depressor
maxillae inferioris_. The curve so formed and the descending limb are
covered by the _M. depressor maxillae inferioris_. The artery then
passes backwards to form a rich anastomosis in the skin almost as far
as the posterior end of the trunk. It supplies the following branches:--
(1) The _Ramus dorsalis_ (Virchow) arises immediately in front of the
curve of the main artery; it ascends behind the _M. temporalis_, and
passes along the anterior border of the _M. depressor maxillae_ to the
skin, where it curves backwards. It supplies small twigs forwards as
far as the eyelids.
(2) The _Ramus auricularis_ (Virchow) also arises in front of the
curve in the cutaneous artery; sometimes it arises from the _Ramus
dorsalis_. The artery winds around the _M. petrohyoideus III_ near its
insertion, and so reaches the posterior wall of the tympanic cavity,
where it anastomoses with the _R. auricularis_ of the _Ramus maxillaris
communis_.]
(3) The _Arteria pharyngo-maxillaris_ (Fig. 148 _p.m._) is a small
branch running forwards and outwards to supply the mucous membrane of
the larynx, Eustachian tubes, gums, the lower jaw, and the skin under
the mouth. It forms a rich anastomosis with branches of the _Ramus
maxillaris inferior_ of the occipital artery, and with others from the
pharyngeal branch of the carotid artery; a large branch passes forwards
to supply the skin of the throat and floor of the mouth.
(4) The _Arteria cutanea pectoris_ (Fig. 149 _c.p._) is distributed to
the skin of the breast.
*4.* The *subclavian artery* (_Arteria subclavia_), (Fig. 150 _s_). The
subclavian artery arises from the systemic arch immediately behind the
occipito-vertebral artery at the level of the second or third vertebra.
The artery then runs outwards alongside and in front of the brachial
nerve, between the _M. subscapularis_ and the _M. triceps_ to the arm,
where it is known as the brachial artery; in its course it gives off:--
*a.* The _Arteria costo-cervicalis_ (Fig. 150, 1). This artery arises
near the systemic arch, and runs backwards, parallel to the vertebral
column, over the brachial nerve, and across the transverse processes of
the vertebrae. It is distributed more especially to the _M. obliquus
internus_.
*b.* The _Arteria coraco-clavicularis_ (Fig. 150, 2) arises more
externally than the last artery; it accompanies the coraco-clavicular
nerve on the dorsal surface of the ventral portion of the
shoulder-girdle, and passes between the _M. deltoideus_ and _M.
subscapularis_ into the _Foramen ovale_, where it divides to supply
these muscles and the _M. pectoralis_.
[Illustration: Fig. 150.
Subclavian artery of the left side.
_A_ Systemic arch.
_A_′ Dorsal aorta.
_c_ Arteria cutanea medialis superior.
_c_′ Arteria cutanea medialis inferior.
_ls_ M. levator scapulae.
_o.v_ Occipito-vertebral artery.
_p_ Arteria pectoralis.
_R_ Radial artery
_s_ Subclavian artery.
_U_ Ulnar artery.
1 Arteria costo-cervicalis.
2 Arteria coraco-clavicularis.
3 Arteria scapularis posterior.
4 Arteria scapularis superior.
5 Cutaneous artery.
6 Arteria subscapularis.
]
*c.* The _Art. scapularis posterior_ (Fig. 150, 3), a small branch
arising opposite at the tip of the second transverse process and
passing backwards over the _MM. transverso-scapulares_, to which it is
distributed.
[Illustration: Fig. 151.
Arteries of the palmar surface of the hand.
_B_ Ulnar artery.
_ci_ R. cutaneus medialis inferior.
_d_ Digital branches.
_F_ M. flexor digitorum communis.
_II_ Thumb.
_V_ Fifth finger.
]
[Illustration: Fig. 152.
Arteries of the dorsal surface of the hand.
_B_ Ulnar artery.
_cri_ R. cutan. rad. inferior.
_R_ Radial artery.
_II_ Thumb.
_V_ Fifth finger.
]
*d.* The _Art. scapularis superior_ (Fig. 150, 4) accompanies several
nerves between the _M. subscapularis_, _M. transverso-scapularis
major_, and the long head of the _M. triceps_ towards the dorsal
surface, where it is distributed to the _MM. infraspinatus_,
_latissimus dorsi_, etc.
*e.* The _Ramus cutaneus maxillaris_.
*f.* The _Art. subscapularis_ (Fig. 150, 6) is distributed in the
subscapular muscle.
A. The *brachial artery* (_Arteria brachialis_), (Fig. 150) accompanies
the brachial nerve under cover of the long head of the _M. triceps_ and
over its inner head to the _Plica cubiti_, into which it sinks near the
tendon of the _M. sternoradialis_; beyond this point it is continued as
the ulnar artery. In its course the brachial artery gives off:--
*a.* The _Arteria pectoralis_ (Fig. 150 _p_).
*b.* The _Arteria cutanea medialis superior_ (Fig. 150 _c_).
*c.* The *radial artery* (_Arteria radialis_), (Fig. 150 _R_) which
winds round the humerus with the radial nerve between the muscles of
the outer side of the forearm, to which it gives branches: in the palm
of the hand it passes between the _M. extensor carpi ulnaris_ and the
_M. flexor antibrachii_ to the dorsal surface of the hand, where it
anastomoses with the ulnar artery. In its course it supplies:--
(1) Muscular branches to the surrounding muscles.
(2) The _Ram. cut. radialis inferior_, which arises from the radial
artery towards the distal end of the forearm, and passes underneath the
_M. flexor carpi ulnaris_ to the skin.
B. The *ulnar artery* (_Arteria ulnaris_), (Figs. 150 _U_, 151 _B_)
accompanies the ulnar nerve towards the hand, passes between the _M.
flexor digitorum communis_ and the _M. anconeus_ to the palm of the
hand, and then winds round the outer side to the dorsal surface of the
carpus to form its terminal branches. The branches are:--
(1) The _Ram. cutan. med. inferior_ (Fig. 151 _ci_); it arises near the
wrist-joint and supplies (α) twigs to the skin of the inner surface;
(β) a branch downwards, which courses along the inner side of the
second finger to its tip; and (γ) a branch which passes upwards to
anastomose with the _R. cutaneus medialis superior_.
(2) In the palm of the hand a branch (Fig. 151 _d_) is given off,
which divides to form _Arteriae digitales volares_: one for the second
finger, two for the third finger, two for the fourth finger, and one
for the fifth finger.
(3) Given off on the dorsum of the hand (Fig. 152) it supplies branches
corresponding exactly with those of the palmar surface.
*5.* The *dorsal aorta* (_Aorta communis s. abdominalis_) (Fig. 153
_A_). The two systemic arches unite at about the level of the sixth
vertebra to form the dorsal aorta: as already mentioned the union is
very incomplete, the dorsal aorta being practically a continuation of
the right systemic arch, and only communicating with the left by means
of a small opening. The branches are as follows:--
*a.* The *coeliaco-mesenteric artery* (_Arteria intestinalis
communis_), (Fig. 153), the true continuation of the left systemic
arch, at once divides to form the gastric and mesenteric arteries.
(1) The *gastric artery* (_Arteria gastrica s. coeliaca_) (_c_)
immediately divides into two branches:--
α. The _Ramus dexter s. anterior_; this artery gives off the _Arteria
hepatica_ to the liver and gall-bladder and passes to the right
(anterior) surface of the stomach, running along the attachment of
the mesentery and supplying branches forwards to the oesophagus and
backwards towards the intestine.
β. The _Ramus sinister s. posterior_ passes to the left (posterior)
surface and behaves like the _Ram. dexter_.
(2) The *mesenteric artery* (_Arteria mesenterica superior_ and
_inferior_, and the _Arteria splenica_), (Fig. 153 _m_) supplies:--
α. The superior mesenteric artery, which supplies the upper part of
the intestine, and gives off a recurrent branch to the stomach, which
anastomoses with the gastric arteries.
[Illustration: Fig. 153.
Arterial system of _Rana esculenta_.
_A_ Dorsal aorta.
_Ad_ Right systemic arch.
_As_ Left systemic arch.
_c_ (opposite fore-limb) Carotid artery.
_c_ (in abdomen) Coeliac artery.
_cm_ Cutaneous artery.
_e_ Lingual artery.
_H_ Heart.
_H_′ Harderian gland.
_L_ Liver.
_Lu_ Lung.
_m_ Mesenteric artery.
_M_ Stomach.
_M_′ Spleen.
_o_ Ophthalmic artery.
_p_ Pharyngeal artery.
_p_′ Anterior palatine artery.
_S_ Subclavian artery.
_I_ Carotid arch.
_II_ Systemic arch.
_III_ Pulmo-cutaneous arch.
]
β. The splenic artery to the spleen.
γ. The inferior mesenteric artery to the lower part of the intestine.
All the arteries to the intestine course in lymph-spaces.
*b.* The *urinogenital arteries* (_Arteriae urino-genitales_),
(Fig. 154 _ug_) are four to six small arteries arising from the ventral
surface of the aorta between the kidneys: they immediately divide into
right and left branches to supply the kidneys, fat-bodies, reproductive
organs, and their ducts (see kidney).
*c.* The *lumbar arteries* (_Arteriae lumbales_), are small paired
vessels to the neighbouring muscles, and send branches through the
intervertebral foramina to the vertebral canal. Sometimes these
arteries arise from the _Art. spinalis_ or _Art. vertebralis_, etc.;
in the former case they pass outwards from the vertebral canal to the
surrounding structures.
*d.* The *haemorrhoidal artery* (_Art. mesenterica inf. s Art.
haemorrhoidalis superior_) is a small median artery running from the
posterior end of the aorta to the large intestine.
*6.* *Bifurcation of the aorta.* *The iliac arteries* (_Arteriae
iliacae communes_). Opposite the middle of the urostyle the aorta
bifurcates to form the iliac arteries; each of these courses on the
corresponding sciatic plexus to the thigh, beyond which it is continued
as the sciatic artery. The branches of the iliac artery are:--
*a.* The *vesico-epigastric artery* (_Arteria epigastrico-vesicalis_),
(Fig. 155 _ev_); it arises near the bifurcation, passes outwards on the
plexus, and divides into two branches:--
(1) The epigastric artery (_Arteria epigastrica_) (_e_) immediately
gives off a recurrent branch to the iliac bone and the _M.
ilio-coccygeus_; it then continues to the ventral muscles of the
abdominal wall, where it runs forwards on the deeper surface of the _M.
obliquus internus_, and is distributed more especially to this muscle.
[Illustration: Fig. 154.
The urinogenital arteries.
_A_ Dorsal aorta.
_H_ Testis.
_N_ Kidney.
_ug_ Urinogenital arteries.
]
(2) The hypogastric artery (_Arteria vesicalis_) (_v_) winds downwards
around the sciatic plexus to reach the mesentery, along which it
courses to the bladder, where it forms a rich anastomosis.
*b.* The *femoral artery* (_Arteria femoralis s. cruralis_), (Fig. 155
_f_) is the representative of the femoral artery of man, although it
does not perform the same functions. The artery passes under the hinder
free border of the _M. obliquus internus_ to the thigh, where it lies
upon the _M. ilio-psoas_, and sends twigs to the neighbouring muscles,
the skin, and lymph-sac (_Lamina inguinalis_), and then divides into:--
(1) A twig, which runs forwards on the ventral surface of the iliac
bone and is covered by the epigastric artery.
(2) A twig, running forwards and downwards on the _MM. ilio-psoas_,
_vastus internus_, and _sartorius_, to send branches to the hip-joint.
*c.* The *spermatic artery* (_Arteria spermatica_), which arises, in
males, from the iliac artery, and ascends to the _Vesicula seminalis_.
[Illustration: Fig. 155.
Bifurcation of the aorta and the iliac arteries.
_e_ Epigastric artery.
_ev_ Vesico-epigastric artery.
_f_ Femoral artery.
_o_ Internal oblique muscle.
_v_ Vesical artery.
]
*7.* *Arteries of the hinder extremity.*
A. The *sciatic artery* (_Arteria ischiadica_), (Fig. 156 _i_) is
the continuation of the iliac artery; it leaves the pelvis between
the hinder (outer) border of the _M. coccygeo-iliacus_ and the inner
surface of the origin of the _M. ilio-psoas_, then lies between the
former muscle and the origin of the _M. vastus externus_. It appears
on the thigh between the _M. vastus externus_ (in front) and the _M.
pyriformis_ (behind); it is the main arterial trunk for the hinder
extremity. The artery courses backwards, lying upon the sciatic
nerve and between the _M. biceps_ and the _M. semimembranosus_; in
this course it runs in a lymph-space placed in the _Septum femorale
superius_ (see page 259). Arrived at the popliteal space the artery
bifurcates to form the peroneal and tibial arteries; near the pelvis
it gives off two branches (*a*) and (*b*), and in its course along the
thigh two branches (*c*) and (*d*).
*a.* The _Art. haemorrhoidalis inferior_ (_h_) runs backwards and
inwards under the _M. pyriformis_ to be distributed in the _M.
sphincter ani_ and the skin of the anus.
*b.* The _Art. cutanea femoris posterior v. superior_ (_cf_′) runs
with the corresponding nerve and the _M. pyriformis_, and over the _M.
semimembranosus_ to the skin of the inner and hinder surfaces of the
thigh.
*c.* The _Rami musculares_ supply the _M. semimembranosus_, the _M.
biceps_, and the _MM. extensores auris_; the branch to the _M. rectus
inferior major_ pierces the muscle in company with the nerve, and is
continued as:--
*d.* The _Art. cutanea femoris media_ (_cf_″) to the skin of the middle
of the inner surface of the thigh. Several small twigs pierce the _M.
rectus internus minor_, reach the skin, and communicate with this
artery.
[Illustration: Fig. 156.
Arteries of the hinder extremity.
_cc_ Art. cutanea calcanei.
_cf_ Cutaneous branch of the femoral artery.
_cf_′ Art. cutanea fem. post. superior.
_cf_″ Art. cutanea femoris media.
_cgl_ Art cut. genu lateralis superior.
_cgl_′ Art. circumflexa genu lateralis inferior.
_cgm_ Art. circumflexa genu superior medialis.
_cgm_′ Art. circumflexa genu inferior medialis.
_ci_ M. coccygeo-iliacus.
_g_ M. gastrocnemius.
_gl_ M. glutaeus.
_h_ Art. haemorrhoidalis inferior.
_i_ Sciatic artery.
_ml_ Art. malleolaris lateralis.
_mm_ Art. malleolaris medialis.
_p_ Art. peronea.
_p_′ Muscular branch to the M. peroneus.
_P_ M. pyramidalis.
_ra_ M. rectus anterior.
_ri_″ M. rectus internus.
_sm_ M. semimembranosus.
_su_ Art. suralis.
_t_ Tibial artery.
_to_ Aperture in tibio-fibula.
_tr_ Art. tarsea.
_ve_ M. vastus externus.
]
B. The *peroneal artery* (_Art. peronea_), (Fig. 156 _p_) runs
outwards under cover of the tendon of the _M. biceps femoris_, and
accompanies the peroneal nerve downwards to give off:--
*a.* The _Art. circumflexa genu lateralis superior_, which runs
forwards on the outer side of the knee, gives a twig to the joint, and
is continued as:--
*b.* The _Art. cutanea genu lateralis superior_ (_cgl_) to the skin of
the anterior and outer sides of the knee. It anastomoses with branches
of the _Arteriae circumflexae genu mediales_ to form a rich anastomosis
(_Rete articulare genu_): other branches pass upwards to inosculate
with the _Art. cutanea femoris anterior_ (_cf_), and others downwards
to anastomose with the next artery.
*c.* The _Art. circumflexa genu lateralis inferior_ (_cgl_′) runs under
the tendon of origin of the gastrocnemius to the outer side of the
knee, and terminates in the skin as the _Art. cutanea genu lateralis
inferior_. Some of the cutaneous twigs pass upwards to anastomose with
the _Art. cut. genu lat. superior_, others downwards to anastomose with
the _AA. malleolares_.
*d.* A muscular branch (_p_′) for the _M. peroneus_; it is the real
continuation of the peroneal artery, and runs behind the outer tendon
of origin of the gastrocnemius to be distributed in the _M. peroneus_.
C. The *tibial artery* (_Arteria tibialis_), (Fig. 156 _t_), arises at
the bifurcation of the sciatic, and runs inwards, meeting the tibial
nerve between the tendons of origin of the _M. gastrocnemius_, and
deep in the popliteal space under cover of the calf-muscles. It then
pierces the _M. tibialis posticus_, and leaves this to perforate the
tibio-fibula (see p. 50), appearing again on the anterior surface as
the anterior tibial artery. Before meeting the tibial nerve this artery
gives off the following branches:--
*a.* The _Art. circumflexa genu superior medialis_ (_cgm_), which winds
round to the front of the knee-joint, and gives off a cutaneous branch,
the _Art. cutanea genu medialis superior_, which is distributed in the
skin of the inner side of the knee and anastomoses above with the _Art.
cutanea femoris media_, below with the following branches (*b*, *c*,
and *d*).
*b.* The _Art. circumflexa genu inferior medialis_ (_cgm_′) supplies
twigs to the knee-joint, and passes to the skin of the knee and inner
surface of the calf as the _Art. cutanea inferior medialis_.
*c.* Muscular twigs to the _M. gastrocnemius_.
*d.* The _Art. suralis_ (_su_); this accompanies the _N. suralis_
downwards along the calf-muscle, and is distributed in the skin of the
inner side of the heel.
*e.* While passing between the fibres of the _M. tibialis posticus_,
the tibial artery gives off muscular twigs; one larger than the rest is
known as the _Ramus descendens_.
D. The *anterior tibial artery* (_Arteria tibialis antica_), (Fig. 157
_t.a._) is the continuation of the tibial artery after piercing the
tibio-fibula. It runs downwards on the anterior surface of the leg,
then between the two heads of the _M. tibialis anticus_ to the dorsum
of the foot, where it is continued as the _Arteria dorsalis pedis_. It
supplies:--
[Illustration: Fig. 157.
Arteries of the dorsal surface of the foot.
_c.c._ Art. cutanea calcanei.
_c.c.i._ Art. cutanea cruris inferior.
_Ft_′ M. flexor tarsi.
_h_ Art. cutanea hallucis.
_i1_ Art. interossea dorsalis I.
_i2_ Art. interossea dorsalis II.
_i3_ Art. interossea dorsalis III.
_i4_ Art. interossea dorsalis IV.
_ml_ Art. malleolaris lateralis.
_m.m._ Art. malleolaris medialis.
_t.a._ Anterior tibial artery.
_ta_* Bifurcation of the dorsalis pedis artery.
_tr_ Art. tarsea.
]
*a.* _Rami musculares_ to the _M. peroneus_, _M. extensor cruris_, and
to the _M. flexor tarsi anterior_.
*b.* The _Art. cutanea cruris inferior_ (_c.c.i._) passes between the
two heads of the _M. tibialis anticus_ to the skin of the anterior and
outer sides of the leg.
*c.* The _Art. cutanea calcanei_ (_c.c._) is given off at the
ankle-joint; it runs outwards on the lower end of the tibio-fibula,
giving branches to the joint, then backwards between the tibio-fibula
and the _M. peroneus_ to be distributed to the skin of the heel. Above
it anastomoses with the _A. circumflexa genu inf. lateralis_, and below
with the malleolar arteries.
*d.* The _Art. malleolaris lateralis_ (_ml_) arises a little beyond
the last artery; it runs outwards under the origin of the _M. flexor
tarsi_, gives branches to the joint and muscles, and terminates in the
skin of the outer border and dorsal surface of the foot.
*e.* The _Art. malleolaris medialis_ (_m.m._) arises at about the
same level as the _Art. malleolaris lat._ from the inner border
of the anterior tibial artery. It supplies branches to the joint,
gives numerous branches to the skin, which anastomose with the _Art.
suralis_, and passes to the inner border of the foot, where it ends by
distributing branches to the _M. plantaris_, the extensor aponeurosis,
and, as the _Art. cutanea plantaris_, to the skin of the sole of the
foot.
E. The *dorsal artery* of the foot (_Art. dorsalis pedis_), (Fig. 157
_t.a._) runs under the _M. flexor tarsi posterior_ to the point _ta_*,
where it is superficial; the artery then bifurcates; the branches are:--
[Illustration: Fig. 158.
Arteries of the sole of the foot.
_i_ Art. interossea.
_pf_ Rami perforantes.
]
*a.* The _Art. tarsea_ (_tr_) which arises from the dorsal artery of
the foot while under cover of the _M. flexor tarsi posterior_; it
passes to the _M. extensor digiti V_ and to the skin of the dorsum and
outer border of the foot. One branch courses along the outer border of
the fifth toe to its tip; another passes upwards to anastomose with the
neighbouring vessels.
*b.* The inner branch, formed by the bifurcation of the dorsal artery
of the foot, at once divides to form:--
(1) The _Art. cutanea hallucis_ (_h_) to the supplemental great toe.
(2) The _Art. interossea dorsalis I_ (_i^1_), which at once bifurcates
to form two _Rami digitales_ for the first and second toes; these
inosculate with the _Art. cutanea plantaris_, and send twigs to the
skin of the inner border of the foot.
*c.* The outer branch formed by the bifurcation of the dorsal artery
divides to form the _Arteriae interossei dorsales II_, _III_, and _IV_
(_i^2_, _i^3_, _i^4_); they are distributed in a rich anastomosis to
the web.
*d.* The _Arteria interossea_ (Fig. 158 _i_) arises from the dorsal
artery of the foot at the tarsus, and perforates the membrane between
the astragalus and calcaneum to reach the sole of the foot. It forms a
rich subcutaneous plexus on the calcar, and anastomoses with the _Rami
perforantes_ (Fig. 158 _pf_), which pass above the upper borders of the
_Musculi interossei_ to reach the plantar surface, where they give off
small _Rami interossei volares_ to anastomose with the _AA. interosseae
dorsales_.
III. THE VEINS.
(The arrangement of this section has been modified.)
The blood, distributed to the body by means of the arteries, is
returned to the heart by the veins, which conduct the blood directly or
indirectly to the auricles. The pulmonary vein opens directly into the
left ventricle, the three _Venae cavae_ open into the _Sinus venosus_.
A. *Vein opening into the left auricle.*
The *pulmonary vein* (_Vena pulmonalis communis_), (Fig. 159 _vp_).
The blood returning from each lung is gathered into a vessel lying
along the inner side of the root of the lung. That of the right side
is somewhat longer than the left; the two vessels (_Venae pulmonales
dextra et sinistra_) run above the corresponding anterior caval veins
to form a common trunk, the pulmonary vein, which opens into the left
auricle (see p. 215).
B. *Veins opening into the* _Sinus venosus_.
The veins opening into the _Sinus venosus_ are the three caval veins;
of these the two anterior open into the anterior angles of the _Sinus
venosus_, the posterior into the posterior angle.
*1.* The *Anterior Caval Veins* (_Vena cava superior_), (Figs. 133 _V_,
159 _C a_) are a pair of large veins opening into the _Sinus venosus_
and returning to it blood from the fore-limbs and sides of the head.
Each vein is formed by the union of a small vein, the external jugular,
with two large veins, the innominate and the subclavian veins.
*a.* The *external jugular vein* (_Vena jugularis externa_), (Fig. 159
_je_) is formed, at the outer border of the hyoid bone, by the union of
two veins:--
(1) The lingual vein (_Vena lingualis_) (Fig. 161 _l_). This originates
at the tip of the tongue and passes in a very tortuous course along the
ventral surface of the hyoid; it receives numerous branches from the
tongue and hyoid muscles.
(2) The mandibular vein (_Vena maxillaris inferior_), (Fig. 161 _m_)
runs along the insertion of the _M. submaxillaris_, and turns inwards
at its hinder border to join the lingual vein.
*b.* The *innominate vein* (_Vena anonyma_), (Fig. 160 _A_) is formed
by the union of the internal jugular and the subscapular veins. By
tracing the innominate vein upwards between the suspensorium and the
shoulder-girdle, the internal jugular vein will be seen to receive
the vertebral vein at the outer border of the _M. levator scapulae_.
The left innominate vein receives the _Vena bulbi anterior_ from the
_Truncus arteriosus_ (p. 222).
[Illustration: Fig. 159.
Schema of the veins of _Rana esculenta_.
_a_ Subclavian vein.
_ab_ Anterior abdominal vein.
_Ad_ Right auricle.
_As_ Left auricle.
_Ca_ Anterior vena cava.
_Cp_ Posterior vena cava.
_cm_ Cutaneous vein.
_d_ Vena dorso-lumbalis.
_D_ Intestine.
_f_ Femoral vein.
_i_ Sciatic vein.
_ic_ Vena communicans iliaca.
_je_ External jugular vein formed by lingual and maxillary
veins _l_ and _m_.
_ji_ Internal jugular vein.
_L_ Hepatic veins.
_N_ Kidney.
_o_ Oviducal veins.
_P_ Hepatic portal vein.
_raI_ Renal portal vein.
_raII_ Secondary renal portal veins.
_re_ Renal veins.
_s_ Subscapular vein.
_SC_ Sinus venosus.
_va_ Innominate vein.
_vc_ Vena bulbi posterior (cardiac vein).
_vp_ Pulmonary veins.
]
(1) The *internal jugular vein* (_Vena jugularis_), (Fig. 160 _J_)
can be traced from the border of the _M. levator scapulae_ upwards
and forwards to the hinder part of the prootic bone: it then passes
forwards under the lateral process of the prootic, in a groove on the
anterior surface of the same bone, towards the hinder angle of the
orbit, where it receives the veins from the cranial cavity (see vessels
of brain, p. 165), and also a branch from the orbit.
[Illustration: Fig. 160.
Distribution of the internal jugular vein and the anterior portion of
the cutaneous vein.
_A_ Innominate vein.
_c.m._ Cutaneous vein.
_f_ Nasal vein.
_h_ Harderian gland.
_H_ Skin, reflected downwards.
_J_ Internal jugular vein.
_L_ Anterior lymph-heart.
_l_ M. levator scapulae.
_O_ M. obliquus internus.
_o_ Vena orbitalis anterior.
_o_′ Vena orbitalis posterior.
_P_ Lateral process of the prootic bone.
_S_ Subscapular vein.
_S_′ Shoulder-girdle.
_T_ Tympanic membrane.
_V_ Vertebral vein.
_2_ Transverse process of the second vertebra.
_3_ Transverse process of the third vertebra.
_4_ Transverse process of the fourth vertebra.
]
α. [The _Vena orbitalis media_ (Virchow); it arises from the anterior
internal angle of the orbit, from the Harderian gland, the nasal
cavity, or from other veins on the anterior wall of the orbit. The
vessel lies close to the cranium, immediately underneath the _Arteria
nasalis_, and sinks under the _M. rectus superior_ to join the internal
jugular vein. In its course it receives the _Vena bulbi superior_ (see
eye), and near its termination communicates with the _Vena orbitalis
posterior_.]
β. The _Vena vertebralis_ (Fig. 160 _V_) arises posteriorly and runs
forwards over the transverse processes of the vertebrae, the _Musculi
intertransversarii_, and the _M. levat. scapulae_, to join the internal
jugular vein. In its course it receives branches (_Venae spinales_)
from the vertebral canal through the intervertebral foramina, and
cutaneous branches which accompany the corresponding arteries and
nerves through the dorsal lymphatic sac. The vein pulsates in
consequence of its connection with the anterior lymph-heart (Müller).
(2) The *subscapular vein* (_Vena subscapularis_), (Fig. 160 _S_). This
vein arises in the transverse abdominal muscles and the muscles of the
shoulder girdle; it unites with the internal jugular vein under the
shoulder-girdle.
*c.* The *subclavian vein* (_Vena subclavia_), (Fig. 159) passes
backwards from the anterior caval vein on the dorsal surface of the
coracoid bone and the clavicle, and then under cover of the _Portio
sternalis_ of the _M. pectoralis major_, to the internal border of the
_Portio abdominalis_ of the _M. pectoralis major_, where it is formed
by the union of the cutaneous vein and the brachial vein.
[Illustration: Fig. 161.
The anterior caval vein and its branches.
_a_ Innominate vein.
_c.m._ Cutaneous vein.
_c.s._ Anterior cava vein.
_i_ Internal jugular vein.
_i_′ External jugular vein.
_l_ Lingual vein.
_m_ Mandibular vein.
_s_ Brachial vein.
_s.c._ Subscapular vein.
]
(1) The cutaneous vein (_Vena cutanea magna_, Ecker; _Vena
musculo-cutanea_, Gruby), (Figs. 160, 161, and 162 _c.m._). This vein
arises by small branches in the head; these are:--
α. The _Vena nasalis_ (Virchow); it arises by an upper and a lower
branch from around the nostril, and courses backwards along the
superior maxillary bone to about the middle of the orbit, where it
joins the facial vein.
β. The _Vena orbitalis anterior_ (Virchow), (_Vena ophthalmica
anterior_, Ecker), (Fig. 160 _o_) commences at the Harderian gland from
a rich anastomosis, receives branches from the floor and anterior wall
of the orbit, and joins the facial vein with the _Vena nasalis_.
[Illustration: Fig. 162.
Course of the cutaneous vein as seen from the side.
_c.m._ Cutaneous vein.
_d_ M. depressor maxillae.
_i_ M. infraspinatus.
]
γ. The _Vena orbitalis posterior_ (Virchow), (_Vena ophthalmica
posterior_, Ecker), (Fig. 160 _o_′) arises on the posterior wall of
the orbit on the _M. pterygoideus_; it passes under the _Processus
zygomaticus_ to join the facial vein, and in its course receives the
_Vena ophthalmica_ (see eye), and communicates with the _Vena orbitalis
medialis_ and the internal jugular vein.
δ. The _Vena facialis_ (Fig. 160) is formed about the middle of the
orbit by the union of the _Vena nasalis_ and the _Vena orbitalis
anterior_; it courses backwards towards the angle of the jaw. On
reaching the _M. depressor maxillae_, about 4 mm. in front of the angle
of the jaw, it passes on to the skin. It receives in its course the
_Venae palpebrales_ (Fig. 162) and the _Vena orbitalis posterior_.
The musculo-cutaneous vein is the direct continuation of the _Vena
facialis_ after this has left the upper jaw; it immediately receives
one or more twigs (_Venae tympanicae_), (Fig. 162) from the tympanic
membrane and the tympanic cavity.
The vein then courses backwards in the outer wall of the lateral
lymph-sac as far as the middle of the trunk, where it passes, by
means of the _Septum abdominale_, to the outer border of the _Portio
abdominalis_ of the _M. pectoralis_; here the vein curves round to pass
forwards between the fibres of this muscle to its inner border where it
terminates by joining the brachial vein. In the whole of this lengthy
course the vein receives numerous branches from the neighbouring parts.
[Illustration: Fig. 163.
Veins in the region of the kidney.
_a_ Renal portal vein.
_a_′ Dorso-lumbar veins.
_abd_ Anterior abdominal vein.
_d_ Intestine.
_f_ Femoral vein.
_i_ Sciatic vein.
_N_ Kidney.
_o_ Right ovary, drawn to the left.
_o_′ Oviduct.
_ov_ Oviducal veins.
_p_ Mesenteric veins.
_r_ Renal veins.
_V_ Bladder.
_v.c.i._ Posterior vena cava.
_Vv_ Vesical veins.
]
(2) The *brachial vein* (_Vena brachialis_) is formed in the _Plica
cubiti_ by the union of two veins.
α. The *radial vein* (_Vena radialis_) arises on the dorsum of the hand
from a venous arch, the distal convexity of which receives the _Venae
digitales dorsales_: the vein courses superficially along the outer
side of the forearm to the elbow.
β. The *ulnar vein* (_Vena ulnaris_) arises from the veins in the
palm of the hand, and courses towards the elbow, lying deeply between
the muscles of the inner and outer surfaces of the forearm. In
the elbow the vein becomes superficial near the tendon of the _M.
sterno-cleidoradialis_, and joins the radial vein to form the brachial
vein.
The cutaneous veins of the fore-limb follow courses corresponding with
those of the arteries.
*2.* The *Posterior Caval Vein* (_Vena cava inferior_), (Fig. 159
_Cp_, 163 _v.c.i._). The posterior caval vein is a median vein
which, commencing between the kidneys, runs forwards to open into the
posterior end of the _Sinus venosus_. It receives the hepatic, renal,
and ovarian or spermatic veins.
*a.* The hepatic veins (_Venae hepaticae_), (Fig. 164 _v.h._) are
two in number, one from either side of the liver; they open into the
posterior caval vein near the _Sinus venosus_.
*b.* The *renal veins* (_Venae renales_ or _Venae revehentes_),
(Fig. 163 _r_) are four or five small vessels on each side; they pass
from the inner border of the kidney inwards and forwards, to form,
by their union, the posterior caval vein. The most anterior receive
branches from the fat-bodies (see kidney).
*c.* The *spermatic* or *ovarian veins* are four or five in number on
each side; they open into the posterior caval vein between the renal
veins.
*3.* The *Portal Systems*.
[There are, in the frog, two portal systems; the renal and the
hepatic. Each of these receives vessels which are derived, directly or
indirectly, from the veins of the hinder extremity.
The femoral vein on entering the pelvis divides to form two branches;
an iliac vein placed dorsally, and a pelvic vein placed ventrally; the
two pelvic veins converge to the middle line of ventral wall of the
abdomen, where they unite to form the anterior abdominal vein.]
*a.* The *renal portal vein* (_Vena renalis advehens princeps_),
(Fig. 163 _a_). This vein is formed by the union of the sciatic and the
iliac veins; it courses forwards to the outer border of the kidney, and
is distributed, by numerous branches, to that organ, chiefly on its
dorsal surface. It receives the following veins:--
(1) The *iliac vein* (_Vena iliaca externa_); this is the dorsal branch
formed by the bifurcation of the femoral vein.
(2) The *sciatic vein* (_Vena ischiadica_), (Figs. 163 and 165 _i_)
arises at the popliteal space, courses upwards in company with the
sciatic nerve between the _M. semitendinosus_ and the _M. biceps_, then
passes, still with the nerve, between the _M. vastus externus_ and the
_M. pyramidalis_ into the pelvis. It continues forwards to join the
iliac vein. At the root of the thigh this vein communicates with the
femoral vein by the _Ramus communicans iliacus_.
(3) The *dorso-lumbar vein* (_Vena dorso-lumbalis_), (Fig. 163 _a_′)
is a vein (or more usually several) arising by twigs in the dorsal and
outer walls of the abdomen; it joins the renal portal vein opposite the
kidney.
(4) The *oviducal veins* (Fig. 163 _ov_) are irregular veins from the
oviducts, which open either into the dorso-lumbar vein, or into the
renal portal vein.
*b.* The *hepatic portal system*.
The liver receives blood from two sources: (1) from the hind-limbs by
means of the anterior abdominal vein, and (2) from the alimentary canal
by the hepatic portal vein.
[Illustration: Fig. 164.
Veins of the liver.
_AA_ Auricles.
_aa_ Right and left branches of anterior abdominal vein.
_b_ Ramus descendens.
_c_ Vena bulbi (Vena cardiaca).
_D_ Intestine.
_G_ Gall-bladder.
_L.l._ Left lobe of liver.
_L.r._ Right lobe of liver.
_P_ Hepatic portal vein.
_P_′ Intestinal veins.
_P_″ Gastric veins.
_S_ Sinus venosus.
_V_ Ventricle.
_Va_ Anterior abdominal vein.
_V.c.i._ Posterior vena cava.
_v.h._ Hepatic veins.
]
The *anterior abdominal vein* (_Vena abdominalis_), (Figs. 159 _ab_,
164 _Va_) is formed, a little in front of the symphysis pubis, by
the union of the two pelvic veins. It courses forwards along the
middle line of the ventral body-wall until opposite the liver, where
it ascends and divides into three branches, of which two enter the
right and left lobes of the liver respectively. The third, the _Ramus
descendens_, joins the hepatic portal vein. The anterior abdominal vein
receives the following veins:--
α. The vesical vein (_Vena vesicalis_), (Fig. 163 _Vv_); a median vein
arising in the groove between the lobes of the bladder from lateral
branches, which extend outwards on the bladder. This vein communicates
above with other vesical twigs which open into the haemorrhoidal vein.
β. Parietal veins, which join the anterior abdominal vein in its course
along the ventral body-wall.
γ. A cardiac vein (_Vena cardiaca_), (Figs. 142, 159 _vc_, 164 _c_),
which joins the anterior abdominal vein just before its division (see
p. 222).
The *hepatic portal vein* (_Vena portarum_), (Figs. 159, 164 _P_) is
formed by the union of the gastric, intestinal, splenic, and one of
the haemorrhoidal veins. The large vein so constituted passes forwards
towards the liver, receives the _Ramus descendens_ from the anterior
abdominal vein, and then passes into the left lobe of the liver. Its
branches are the following:--
(1) The *gastric veins*. The stomach has three veins:--
α. [The _Vena coronaria ventriculi_, which receives blood from the
hinder end of the oesophagus and anterior portion of the stomach.
β and γ. Two other veins which form an _Arcus coronarius_ on the
concave surface of the stomach; the hinder receiving in addition the
small _Venae pancreaticae_ and the _Vena duodenalis_; the trunk so
formed receives the _Vena coronaria ventriculi_ (Hoffmann).
(2) The *intestinal veins*; the veins of that portion of the alimentary
canal between the middle of the duodenum and the anterior end of the
large intestine open into a common vein which joins the hepatic portal
vein.
(3) The *splenic vein* joins either the hepatic portal vein or one of
the intestinal veins.
(4) The *haemorrhoidal veins* are three in number; the anterior opens
into the splenic vein, the remaining two into the portal veins through
the agency of the intestinal veins.]
*4.* *The Veins of the Hinder Extremity.*
The hinder extremity has two venous trunks, the sciatic vein and the
femoral vein.
*a.* The *femoral vein* (_Vena femoralis_), (Fig. 165 _f_) is the
larger venous trunk of the hinder extremity. It arises in the popliteal
space as a direct continuation of the posterior tibial vein, courses
upwards in company with the sciatic artery and nerve, then leaves
these to wind forwards and outwards, and appears between the origins
of the _M. vastus externus_ and of the _M. rectus anterior_. The vein
here gives off the _Ramus communicans iliacus_ to the sciatic vein,
and turns forwards and downwards around the _M. glutaeus maximus_ to
reach the floor of the pelvis, near the femoral artery. The vein then
bifurcates to form the pelvic and iliac veins.
[Illustration: Fig. 165.
Veins of the hinder extremity, half schematic.
_c.i._ Vena communicans iliaca.
_f_ Femoral vein.
_i_ Sciatic vein.
_i_′ Vena cutanea cruris medialis.
_r.a._ M. rectus anterior.
_s.m._ M. semimembranosus.
_v.e._ M. vastus externus.
]
(1) The _Ramus communicans iliacus_ (Fig. 165 _c.i._) forms a
communication with the sciatic at the base of the thigh.
(2) The posterior tibial vein (_Vena tibialis postica_), of which the
femoral is a continuation, arises on the dorsal surface of the toes and
foot. It runs superficially on the _M. extensor longus digiti primi_
over the ankle-joint, courses upwards and winds round the outer surface
of the tibio-fibula to the flexor surface. It receives, in its course,
muscular branches, and at the knee a large cutaneous branch.
*b.* The *sciatic vein*: this vein has already been described (see
p. 247), but the vein from which it arises requires description.
The *anterior tibial* vein (_Vena tibialis antica_) arises on the
dorsum of the foot by twigs from the toes; it courses under the _M.
extensor longus digiti primi_, then upwards on the anterior surface
of the leg, and enters the canal in the tibio-fibula to appear on its
hinder surface. The vein then receives twigs from the _M. peroneus_,
the _M. tibialis posticus_, the _M. gastrocnemius_, and a large
cutaneous branch.
α. The _Vena cutanea cruris medialis_ (Fig. 165 _i_′) receives branches
from both above and below, and enters the popliteal space to join the
anterior tibial vein.
β. The anastomosis on the dorsum of the foot, from which the anterior
tibial vein arises, receives perforating twigs from the plantar surface.
PART II.
THE LYMPHATIC SYSTEM.
(The arrangement of this section has been considerably altered.)
[The lymphatic system of the frog may, for descriptive purposes, be
advantageously treated of in four parts:
*1.* The subcutaneous lymph-sacs.
*2.* The lymph-hearts.
*3.* The lymph-spaces of the body, and those lying between the various
organs.
*4.* The lymph-vessels of the separate organs.
The first two parts will be described in this section; the remainder
with the organs or parts of the body with which they are more
intimately associated. The spleen will be described with the abdominal
viscera.
*1.* The Subcutaneous Lymph-Sacs.
A number of large spaces exist between the skin and the muscles,
in which there is no direct attachment between these parts. These
spaces are separated from each other by thin connective-tissue septa,
stretched between the muscles and the skin, and by attachments of the
skin to the underlying structures.
Joh. Müller first demonstrated that these spaces were connected with
the lymphatic system, and that the contained fluid was lymph. Although
this fact was contradicted by Meyer it received confirmation from
Stannius, Leydig, and especially from Recklinghausen, who showed that
the fluid of the lymph-sacs was carried away by the lymphatics, and
that later it entered the blood-stream.
A. The Lymph-sacs of the Head and Trunk.
*a.* The *septa*. The connective-tissue septa themselves contain
sinuses which occupy the space between their two surfaces (Fig. 166)
these septal sinuses receive the contents of the cutaneous
lymph-vessels and forward their contents into lymph-vessels situated
in the septa. Such a sinus is shown in transverse section in Fig. 166
which is a section of the ventral septum. The same sinus, in plan, is
seen in Fig. 167.
(1) The *dorsal septum* (_Septum dorsale_), (Figs. 169 and 171 _d_) of
each side commences at the tympanic membrane; it is then attached to
the _M. depressor maxillae_, _M. infraspinatus_, and _M. longissimus
dorsi_; and continued backwards over the _M. obliquus abdominis
externus_ to the anterior end of the _M. glutaeus_, whence it extends
along the iliac bone, where it is connected with the posterior
lymph-heart and the _M. pyriformis_, to the tip of the urostyle. At
the tip of the _M. glutaeus_ it is joined by the iliac septum. The
posterior part of the septum is horizontal, and forms the roof of the
iliac lymph-sac.
[Illustration: Fig. 166.
Transverse section of a septum with the attached skin, its contained
sinus injected with blue injection mass.
_H_ Skin.
_s_ Septum.
_S_ Sinus contained in the septum.
]
[Illustration: Fig. 167.
The _sinus abdominalis lateralis_ (Ecker) injected with blue mass.
_H_ Skin with its lymph-vessels.
_S_ Sinus of the septum with lymph-vessels opening into it.
_s_ The septum cut parallel with the skin.
]
(2) The *ventral septum* (_Septum abdominale_), (Figs. 169, 170, and
171 _a_), commencing at the _Symphysis pubis_, runs forwards and
outwards, on either side, along the outer border of the _M. rectus
abdominis_ to the _Portio abdominalis_ of the _M. pectoralis_ (_p_‴),
where it is attached, at a right angle, to the pectoral septum; it
then extends forwards, after attachment to the axillary septum, to the
outer angles of the maxillary septum. At the root of the anterior
extremity it divides to enclose the root of the limb, and so form the
axillary septum.
(3) The *pectoral septum* (_Septum pectorale_), (Figs. 170 and 171 _p_)
is attached to the superficial surface of the _M. pectoralis_ (_Portio
sternalis_, _anterior_ and _posterior_); it runs transversely across
the body, and is attached at its outer end to the ventral and to the
maxillary septa. The septum passes obliquely backwards and downwards to
be attached to the skin, and so forms a very acute angle with the _M.
cutaneus pectoris_ (_cp_): a vertical band of connective-tissue, broad
behind, narrow in front, extends in the middle line from the septum
to the body wall; from it a certain amount of loose connective-tissue
extends in all directions, and forms open lymph-spaces between the _MM.
cutanei pectorales_ and the vertical septum.
(4) The *perineal septum* (_Septum perineale_), (Fig. 170 _pe_). This
median septum extends from the attachment of the dorsal septum to the
tip of the urostyle, backwards to the symphysis pubis, where it joins
the ventral septa. In its attachment it follows the middle line of the
perineum.
(5) The *maxillary septum* (_Septum maxillare_), (Figs. 170, 171
_m_) is attached by either extremity to the dorsal septum, near the
tympanic membrane, is continued downwards to unite with the anterior
end of the ventral septum, and then runs across the anterior pectoral
region, forming a curve with the convexity forwards. It has inserted
into it fibres of the _M. submaxillaris_. The septum is formed of very
loose tissue, and frequently contains deposits of fat; it encloses a
well-marked septal sinus, the _Sinus thoracicus transversus_ (Ecker).
[Illustration: Fig. 168.
Sinus thoracicus transversus (Ecker).
_cp_ M. cutaneus pectoralis.
_H_ Skin reflected forwards.
_s_ Sinus with its afferent vessels.
]
(6) The *iliac septum* (Figs. 169, 172 15, 173 _S_′) is a septum
extending from the dorsal septum to the inguinal septum. It is attached
to the dorsal septum opposite the anterior end of the _M. glutaeus_,
and extends outwards and downwards to the inguinal septum. In it the
_M. cutaneus iliacus_ passes from the trunk to the skin.
[Illustration: Fig. 169[64].
The lymph-sacs of _Rana esculenta_, seen from the dorsal surface.
_1_ Dorsal lymph-sac.
_3_ Lateral lymph-sac.
_7_ Brachio-radial lymph-sac.
_9_ Femoral lymph-sac.
_10_ Suprafemoral lymph-sac.
_11_ Interfemoral lymph-sac.
_12_ Crural lymph-sac.
_13_ Dorsal lymph-sac of the foot.
_14_ Plantar lymph-sac of the foot.
_15_ Iliac lymph-sac.
_a_ Ventral septum.
_d_ Dorsal septum.
_f_′ Superior femoral septum.
_f_‴ Intermediate femoral septum.
_i_ Inguinal septum.
_s_ Posterior brachial septum.
_s_‴ Anterior brachio-radial septum.
_V_ Vocal sac.
]
[Footnote 64: In Figs. 168, 169, and 170 the dotted lines denote the
boundaries of the various lymph-sacs.]
(7) The *inguinal septum* (_Lamina inguinalis_, Ecker), (Figs. 169
171), the dotted line near 15, Fig. 172, separates the belly from the
thigh; on the ventral surface it is attached to the groove which forms
the boundary between the belly and thigh; on the dorsal surface it is
more posterior, and is attached to the dorsal surface of the muscles
of the thigh at some little distance from the trunk. It completely
surrounds the root of the hinder limb. It has attached to it the
ventral, dorsal, and iliac septa, together with the septa of the thigh.
*b.* The *lymph-sacs*.
(1) The *dorsal lymph-sac* (_Saccus cranio-dorsalis_), (Figs. 169
and 171 1). This is a large lymph-sac, extending from the tip of
the snout to the tip of the urostyle; it is bounded in front by
the attachment of the skin to the premaxillary bones; the line of
attachment is continued, on either side, along the inner border of the
external nares, then forms a pouch towards the jaw and in front of the
eye, and runs backwards along the upper border of the orbit, where it
is attached to the upper eyelid, to the inner border of the tympanic
membrane. In this course the skin is firmly attached to the underlying
parts. The lateral boundary of the lymph-sac, behind this point, is
formed by the dorsal septum, which separates it from the lateral
lymph-sac.
(2) The *ventral lymph-sac* (_Saccus abdominalis_), (Figs. 170, 171
_2_) is triangular in form, with the base forwards at the breast, and
the apex behind at the pelvic symphysis; it occupies the space between
the skin below and the belly muscles and part of the _M. pectoralis_
above. It is bounded anteriorly by the pectoral septum (_p_) and
laterally by the ventral septa (_a_).
(3) The *lateral lymph-sac* (_Saccus lateralis_), (Figs. 169, 170,
and 171 3) exists on either side; below, the sac is bounded by the
ventral septum (_a_), above by the dorsal septum (_d_), anteriorly by
the maxillary septum (_m_), and posteriorly by the inguinal septum
(_i_) and the wall of the iliac lymph-sac.
(4) The *submaxillary lymph-sac* (_Saccus submaxillaris_), (Figs. 170
and 171 4) is a space between the _M. submaxillaris_ and the skin;
the sac is bounded behind by the maxillary septum, which separates
it from the pectoral lymph-sac, and more laterally from the lateral
lymph-sac. In front and at the sides the skin is firmly attached to the
margin of the mandible.
(5) The *pectoral lymph-sac* (_Saccus thoracicus_), (Figs. 170 and 171
_5_) lies between the submaxillary and ventral lymph-sacs. The sac
is bounded behind by the pectoral septum (_p_), and in front by the
maxillary septum (_m_).
Illustration: Fig. 170.
Lymph-sacs of _Rana esculenta_, seen from the ventral surface.
_2_ Ventral lymph-sac.
_3_ Lateral lymph-sac.
_4_ Submaxillary lymph-sac.
_5_ Thoracic lymph-sac.
_6_ Brachio-ulnar lymph-sac.
_8_ Anterior brachial lymph-sac.
_9_ Femoral lymph-sac.
_11_ Interfemoral lymph-sac.
_12_ Crural lymph-sac.
_13_ Dorsal lymph-sac of the foot.
_14_ Plantar lymph-sac of the foot.
_a_ Ventral septum.
_a_′ Anterior division of ventral septum.
_a_″ Posterior division of ventral septum.
_cf_ Intermediate femoral septum.
_cp_ M. cutaneus pectoris.
_f_″ Inferior femoral septum.
_i_ Inguinal septum.
_i_′ Attachment of inguinal septum to skin.
_m_ Maxillary septum.
_m_′ Attachment of maxillary septum to skin.
_p_ Pectoral septum.
_p_‴ Port. abdom. of the M. pectoralis.
_pe_ Perineal septum.
_r_ M. rectus abdominis.
_ri_″ M. rectus internus minor.
_s_″ Anterior brachio-ulnar septum.
_s_‴ Anterior brachial-radio septum.
_sm_ Musc. submaxillaris.
]
[Illustration: Fig. 171.
The lymph-sacs of _Rana esculenta_, seen from the side.
_1_ Dorsal lymph-sac.
_2_ Ventral lymph-sac.
_3_ Lateral lymph-sac.
_4_ Submaxillary lymph-sac.
_5_ Pectoral lymph-sac.
_9_ Femoral lymph-sac.
_10_ Suprafemoral lymph-sac.
_12_ Crural lymph-sac.
_15_ Iliac lymph-sac.
_a_ Ventral septum.
_d_ Dorsal septum.
_i_ Inguinal septum.
_m_ Maxillary septum.
_m_′ Attachment of M. submaxillaris to the skin.
_p_ Pectoral septum.
_sm_ M. submaxillaris.
_v_ Vocal sac.
]
(6) The *iliac lymph-sac* (_Saccus iliacus_), (Figs. 171 and 172 _15_,
173) does not really belong to the subcutaneous lymph-sacs, as it does
not lie directly under the skin except by a very narrow border. It is
bounded in front by the iliac septum, above by the dorsal septum, and
posteriorly by the inguinal septum. By these boundaries a space is
enclosed, which lies under the dorsal septum and dorsal sac, and at the
same time partly under the lateral sac. In this sac the _M. glutaeus_,
the anterior ends of the _M. vastus externus_, _M. rectus anterior_,
and _M. cutaneus iliacus_, lie free together with the hindmost part
of the _M. obliquus abdominis externus_, and the hinder portion of the
posterior lymph-heart. Anteriorly the floor is depressed between the
_M. obliquus abdominis_ and the _M. glutaeus_, the depression leading
to a canal, which communicates with the abdominal cavity.
B. The Lymph-sacs of the Anterior Extremity.
*a.* The *septa*.
(1) The *axillary septum* (_Septum axillare_), (Figs. 170 _a_′, _a_″,
171) is practically a portion of the ventral septum, which divides at
the root of the arm to enclose it. The dorsal and ventral portions of
this circular septum have received special names.
α. The dorsal axillary septum (_Septum axillare dorsale_) crosses the
_M. triceps_ and joins the pectoral septum.
β. The ventral axillary septum (_Septum axillare dorsale_) passes
through the axilla and joins the pectoral septum.
The circular axillary septum has attached to it the following:--
(2) The *posterior brachial septum* (_Septum brachiale posticum_)
(Fig. 169 _s_); it is attached along the middle line of the extensor
surface of the arm (long head of the _M. triceps_) to the elbow and
to the forearm (_MM. anconaei_), then passes obliquely over the volar
surface of the hand to the fourth finger.
(3) The *anterior brachio-ulnar septum* (_Septum brachiale anticum
ulnare_), (Fig. 170 _s_″) commences at the same point as the foregoing,
passes obliquely over the outer head of the _M. triceps_, and is
continued over the _M. flexor antibrachii lateralis_, _M. supinator
longus_, and _M. extensor digitorum communis_, to the dorsal surface of
the fourth finger.
(4) The *anterior brachio-radial septum* (_Septum brachiale anticum
radiale_), (Fig. 170 _s_‴) passes from the outer angle of the wall of
the pectoral lymph-sac, over the inner head of the _M. triceps_ and _M.
flexor carpi radialis_ to the thumb.
*b.* The *lymph-sacs* are enclosed by these three septa; they are four
in number:--
[Illustration: Fig. 172.
Transverse section through the trunk in the region of the iliac
lymph-sac.
_c_ Urostyle.
_c_′ Skin.
_o_ Muscles of abdominal wall.
_1_ Dorsal lymph-sac.
_3_ Lateral lymph-sac.
_15_ Iliac lymph-sac.
]
(1) The *brachio-ulnar lymph-sac* (_Saccus brachialis ulnaris_),
(Fig. 170 6) is situated between the first and second septa along the
extensor and ulnar surfaces.
(2) The *brachio-radial lymph-sac* (_Saccus brachialis radialis_),
(Fig. 169 7) is placed along the extensor and radial surfaces.
(3) The *anterior brachial lymph-sac* (_Saccus brachialis anticus_),
(Fig. 170 8) lies on the flexor surface between the second and third
septa; it is a long cavity and interrupted by connective-tissue bands,
in which the tendon of the _M. sterno-radialis_ and the nerve and
vessels are situated.
(4) The *axillary lymph-sac* (_Saccus axillaris_) corresponds to the
iliac lymph-sac; it is bounded by the divisions of the ventral septum.
In the hand no large lymph-space exists; the skin is attached by
numerous bands to the underlying structures.
C. The Lymph-sacs of the Hinder Extremity.
*a.* The *septa*.
(1) The *superior femoral septum* (_Septum femorale superius_),
(Figs. 169 and 175 _f_′) is attached above to the inguinal septum near
the posterior lymph-heart; and is continued, from this point, over the
_M. vastus externus_ and along the _M. triceps_ to the knee.
[Illustration: Fig. 173.
Dissection to show the iliac lymph-sac.
_g_ M. glutaeus.
_i.c._ M. ilio-coccygeus.
_m.c._ M. cutaneus iliacus.
_o_ M. obliq. abdom. externus.
_r_ M. rectus.
_S_ Dorsal septum.
_S_′ Iliac septum.
_S_‴ Portion of dorsal septum, which forms
the roof of the iliac lymph-sac.
_v_ M. vastus externus.
* Aperture, by which the iliac lymph-sac
communicates with the abdominal cavity.
]
(2) The *inferior femoral septum* (_Septum femorale inferius_),
(Figs. 170 and 175 _f_″) runs from the inguinal septum near the point
of insertion of the _M. rectus abdominis_, along the _M. rectus
internus minor_ to the knee.
(3) The *intermediate femoral septum* (_Septum femorale intermedium_),
(Figs. 169 and 175 _f_‴) passes from near the posterior lymph-heart
over the _M. semimembranosus_ and the _M. rectus internus minor_ to
join the inferior femoral septum.
[Illustration: Fig. 174.
Plan of attachments of the inferior femoral, inguinal, and perineal
septa. ]
(4) The *tibio-femoral septum* (_Septum femoro-crurale_) is a circular
band, separating the lymph-sacs of the thigh from the leg sac.
(5) The *septa* of the foot. At the ankle joint the skin is closely
attached all round to the underlying parts. Along the outer border
of the foot a septum is attached to the skin externally, and to the
underlying parts, especially the _M. abductor longus digiti primi_,
internally. A similar but weaker band is attached along the outer
border of the foot, especially to the _M. adductor digiti quinti_.
*b.* The *lymph-sacs*.
(1) The *femoral lymph-sac* (_Saccus femoralis_), (Figs. 169, 170,
171, 175 9) covers the lower and outer surfaces of the thigh; it is
bounded by the superior femoral and inferior femoral septa, and in
front by the inguinal septum.
[Illustration: Fig. 175.
Transverse section of the thigh.
_b_ M. biceps.
_f_′ Superior femoral septum.
_f_″ Inferior femoral septum.
_f_‴ Intermediate femoral septum.
_H_ Skin.
_ri_′ M. rectus internus major.
_ri_‴ M. rectus internus minor.
_s_ M. Sartorius.
_sm_ M. semimembranosus.
_ve_ M. vastus externus.
_9_ Femoral lymph-sac.
_10_ Suprafemoral lymph-sac.
_11_ Interfemoral lymph-sac.
]
(2) The *suprafemoral lymph-sac* (_Saccus suprafemoralis_), (Figs. 169,
171, 175 _10_) lies on the upper surface of the thigh, between the
superior and intermediate femoral septa; above it is bounded by the
inguinal septum.
(3) The *interfemoral lymph-sac* (_Saccus interfemoralis_), (Figs. 169,
170, 175 _11_) is a narrow sac on the inner surface of the thigh,
between the inferior femoral septum and the intermediate femoral
septum. It covers the _M. rectus internus minor_, and is interrupted by
numerous bands of tissue which pass from the surface of the muscle to
the skin. It is, therefore, not a simple sac, but a very wide-meshed
trabecular structure of connective-tissue. The sac is triangular in
shape, with the base directed forwards at the inguinal septum.
(4) The *lymph-sac* of the *leg* is a simple sac enclosing the whole
leg, bounded above by the tibio-femoral septum, and below by the
attachment of the skin to the ankle.
(5) The *lymph-sacs* of the *foot*. On the dorsum of the foot the
skin is free, and there is consequently a lymph-sac. On the plantar
surface the skin is attached by numerous connective-tissue bands and
thread-like tendons, particularly to the flexor tendons. The skin of
the dorsal and plantar surfaces meet on the web and enclose a very rich
anastomosis of lymph-capillaries.
*2.* The Lymph-Hearts.
The frog has two pairs of lymph-hearts, one pair anterior, the other
posterior.
[Illustration: Fig. 176.
The anterior lymph-hearts.
_L_ The left anterior lymph-heart.
_l.s._ M. levator scapulae.
_N_ Brachial nerve.
_t.s._ M. transverso-scapularis maior.
_1–4_ Vertebrae numbered from before backwards.
]
A. The *anterior lymph-hearts* (Fig. 176). These organs lie, one on
each side, behind the broad transverse processes of the third vertebra
(Müller, Panizza, Priestley), in a deep triangular space formed by the
separation of the fibres of the _M. intertransversarius_, between the
transverse processes of the third and fourth vertebrae. Each heart is a
rounded sac, slightly elongated anteriorly where it is connected with
the subscapular vein. [The hearts receive lymph from the anterior part
of the body and the surrounding parts, and empty their contents into
the vertebral vein. Each of these hearts is supplied by a branch from
the second spinal nerve (Volkmann, Eckhard, Schiff, Priestley).]
[Illustration: Fig. 177.
The posterior lymph-hearts.
_gl_ M. glutaeus.
_ic_ M. ilio-coccygeus.
_L_ Posterior lymph-hearts.
_p_ M. pyriformis.
_r_ M. rectus.
_ve_ M. vastus externus.
]
B. The *posterior lymph-hearts* (Fig. 177) are situated on either side
of the urostyle in the triangular spaces (Müller, Panizza, Priestley),
bounded externally and above by the _M. glutaeus_, internally and
above by the _M. coccygeo-iliacus_, below and externally by the origin
of the _M. vastus externus_, and below by the _M. pyramidalis_. Each
posterior heart is about two lines long and one broad, with its long
axis placed antero-posteriorly; the outer surface is uneven and
appears to be unequally dilated. The lymph-heart is closely attached
to the surrounding parts, especially to the fascia covering the _M.
ilii-coccygea_, and posteriorly to the _M. levator ani_ and the _M.
pyramidalis_. [The posterior lymph-hearts receive lymph from the parts
surrounding them, and from the hinder extremities, and forward it into
the _V. iliaca communicans_.
The posterior lymph-hearts are each supplied by a branch from the
corresponding coccygeal nerve (Waldeyer) by its dorsal branch. The
lymph-hearts are also in close connection with the sympathetic system
(Waldeyer).]
PART III.
THE BLOOD, LYMPH, AND HISTOLOGY OF THE VESSELS.
[The parts described in this section will be considered very briefly,
and only from an anatomical point of view.
A. The *blood*[65].
[Footnote 65: Mr. Hurst has noticed a frog (R. temporaria) in which the
blood was perfectly colourless.]
The blood varies in colour, according as it is obtained from an artery
or from a vein; from an artery it has a bright red or scarlet colour;
from a vein a darker shade: in the pulmonary vessels these colours are
reversed. The blood consists of a fluid plasma which contains red and
white corpuscles: the whole forming a slightly alkaline, opaque, and
somewhat sticky fluid.
*a.* The *plasma* or _liquor sanguinis_ is a transparent, clear,
slightly yellow fluid, faintly alkaline in reaction.
*b.* The *corpuscles* are of two kinds, colourless and coloured.
(1) The colourless or white corpuscles are subspherical masses of
protoplasm, endowed with the power of spontaneous motion. They are much
fewer than the red corpuscles, though the proportion of white to red
varies considerably. Three chief varieties of colourless corpuscles can
be distinguished, all of which are true cell forms, and behave like
other cells with staining or other reagents. They have no cell-wall,
but are simply nucleated masses of protoplasm. These corpuscles possess
the power of passing through the walls of the blood-vessels, and are
then known as migratory cells; such migratory cells can be found in
nearly all tissues, but more especially in the connective-tissues.
α. Ordinary large colourless corpuscles are large transparent masses of
protoplasm containing one or two nuclei, rarely three or more. The cell
contains few granules, and usually has one or more vacuoles or clear
spaces containing fluid.
β. Granular corpuscles are less numerous than the foregoing, but
larger, and are distinguished by the numerous large dark granules which
they contain. The processes such a corpuscle sends out are hyaline.
γ. Smaller corpuscles also occur varying much in form: they may
consist of a nucleus with a very small amount of hyaline or granular
protoplasm, or of several nuclei with an extremely small amount of
protoplasm.
(2) The *coloured corpuscles* are much more numerous than the
colourless corpuscles; each is a bi-concave, oval disc, about
0.0255 mm. in length, and 0.017 mm in breadth (Gulliver)[66] (R.
temporaria, 0.0235 and 0.0145 mm. respectively). Each corpuscle
possesses an oval nucleus (Hewson)[66], which projects into either
concave surface of the whole corpuscle. These corpuscles do not
possess the power of spontaneous movement; and have no cell-wall. The
corpuscles are of a reddish-yellow colour, and give the blood its
characteristic hue. The colouring matter is haemoglobin, and when
separated it crystallizes in prisms (Preyer). The corpuscles show a
well-marked intracellular and intranuclear network.]
[Footnote 66: Gulliver, Proc. Zool. Soc. London, 1845, Vol. XIII, p. 93
seq.]
[Footnote 67: Hewson, Phil. Trans. 1773, Vol. LXIII, p. 310 seq.]
B. [The *Lymph* and *Chyle*.
The *lymph* is that portion of the blood which has filtered from the
blood-vessels, through the tissues, into the lymphatics. It is a clear,
transparent fluid, containing colourless corpuscles, which agree in
all particulars with the colourless corpuscles of the blood. During
digestion the lymph from the alimentary canal contains particles of
fatty matter, and is then known as *chyle*.] The colourless corpuscles
of the lymph frequently contain portions of red corpuscles or granules
of pigment. Non-nucleated masses of protoplasm and decolourised red
corpuscles (slightly diminished in size) have also been described as
occurring frequently in the lymph (Fuchs[68]).]
[Footnote 68: Fuchs, Virchow’s Arch. 1877, Vol. LXXI, p. 78 seq.]
C. [Histological Remarks on the Vascular System.
*a.* The *heart* has already been described (pp. 216–222).
*b.* The *blood-vessels* present the same structure as the
corresponding vessels in higher animals. The _arteries_ and _veins_
have each the three walls or layers usually described--_Tunica
adventitia_, _Tunica media_, and _Tunica intima_. The only
characteristic to be mentioned is that the _Tunica adventitia_ contains
branched, pigmented corpuscles. The _Nervi vasorum_, especially of the
smaller arteries, are arranged in two plexuses, one in the _Tunica
adventitia_ (His)[69], the second in the muscular coat (J. Arnold)[70].
The fibres of both plexuses are non-medullated, and have the usual
beaded appearance; they communicate freely with each other. The
*capillaries* present, as a rule, the usual structure: such special
arrangements of the capillaries or peculiarities in structure as occur
will be described with the organs in which they are found.
[Footnote 69: His, Virchow’s Arch. 1863, Vol. XXVIII, p. 427.]
[Footnote 70: Arnold, in Stricker’s Handbuch d. Gewebelehre, p. 137.]
*c.* The *subcutaneous lymph-sacs* are lined with a layer of
endothelium resembling the endocardium shown in Fig. 140; the
endothelial layer possesses stomata (see peritoneum), through which the
lymph-sacs communicate with the underlying lymphatics. The endothelium
is continued on to the vessels, nerves, etc., which course through the
sacs, and excludes these from the cavities. As a rule an artery, vein,
and nerve are enclosed in a common sheath.
*d.* The *lymph-hearts* are small saccular bodies with thin transparent
walls, which contain obscurely striated muscle-fibres. The vessels
communicating with the hearts appear to possess valves (Müller). The
walls of the hearts are formed of three layers; an external, compared
by Waldeyer to an _adventitia_, a muscular layer, and an endothelial
lining. The muscular fibres form a close interlacing mass, the fibres
being small, branched (Leydig), and possessed of many nuclei. Among the
muscular fibres are pigmented corpuscles, together with medullated and
non-medullated nerve-fibres, but no ganglion-cells (Volkmann, Waldeyer,
Priestley). The _adventitia_ is a connective-tissue layer with many
pigment cells (Leydig, Hyrtl, Waldeyer).]
SECTION V.
THE ALIMENTARY TRACT WITH ITS APPENDAGES, THE SPLEEN, AND THE
PERITONEUM.
THE ALIMENTARY TRACT, ETC.
LITERATURE.
THE MOUTH.
(Except the mucous membrane of the tongue, for which see organ of
taste.)
*Ducrotay de Blainville, H. M.*, Ostéographie ou description
iconographique comparée du squelette et du système dentaire des
cinq classes d’animaux vertébrés. Paris, 1841.
*Erdl*, Ueber den Bau der Zähne bei den Wirbelthieren, etc. München,
1841.
*Fixen, C.*, De linguae raninae structura. Dorpat, 1857.
*Heincke, F.*, Untersuchungen über die Zähne niederer Wirbelthiere.
Zeitsch. f. wiss. Zool. 1873. Vol. XXIII, p. 495.
*Hertwig, O.*, Ueber das Zahnsystem der Amphibien, etc. Suppl. to
Vol. XI, Arch. f. mik. Anat. 1874.
*Hoffmann, C. K.*, Bronn’s Thierbuch. Leipzig and Heidelberg,
1873–1878. Vol. VI, p. 379.
*Holl, M.*, Zur Anatomie der Mundhöhle von Rana temporaria. Wiener
Acad. Sitzungsb. 1887. Vol. XCV, Pt. III, p. 47.
*Hoyer*, Ueber die Epithelzellen der Froschzunge, sowie über den
Bau der Cylinder- und Flimmerepithelien und ihr Verhältniss
zum Bindegewebe. Arch. f. Anat. u. Physiol. 1858, p. 163; also
Deutsche Klinik, 1857.
*Langer, C.*, Ueber das Lymphgefässsystem des Frosches. Wiener Acad.
Sitzungsb. 1867. Vol. LV, Pt. I, pp. 614–621.
*Leydig*, Die Anuren Batrachier der deutschen Fauna. Bonn, 1877.
*Owen, R.*, Odontography. London, 1840–1845, p. 187.
*Reichel, P.*, Beiträge zur Morphologie der Mundhöhlendrüsen
der Wirbelthiere. Leipzig, 1882; also in Morph. Jahrb. 1882,
Vol. VIII, pp. 1–72.
*Santi Sirena*, Untersuchungen über den Bau und die Entwicklung der
Zähne bei den Amphibien und Reptilien. Verhandl. d. phys.-med.
Gesellsch. in Würzburg, 1872. Vol. II, new series, p. 125.
*Schöbl, J.*, Ueber divertikelbildende Capillaren in der
Rachenschleimhaut nackter Amphibien. Sitzungsb. d. k. b.
Gesellsch. d. Wiss. in Prag. 1878, p. 25; also in Arch. f. mik.
Anat. 1885, Vol. XXV, p. 89.
*Schultze, F. E.*, Das Drüsenepithel der schlauchförmigen Drüsen des
Dünn- und Dickdarms und die Becherzellen (of the pharyngo-oral
cavity). Centralbl. f. d. med. Wiss. 1866, p. 61.
*Schultze, F. E.*, Epithel- und Drüsen-Zellen. Arch. f. mik. Anat.
1867. Vol. III, p. 137.
*Smith, W. J.*, Beitrag zur differentiellen Diagnose der Rana fusca
s. platyrrhinus und Rana arvalis s. oxyrrhinus auf Grund der an
den Gaumenzähnen nachweisbaren Unterschiede. Pflüger’s Arch. f. d.
ges. Physiol. 1883. Vol. XXXII, pp. 581–588.
*Tomes, C. S.*, On the development of the teeth of the newt, frog,
slowworm, and green lizard. Phil. Trans. 1874, p. 285.
*Török*, Untersuchungen über die Entwickelung der Mundhöhle, etc.
Wiener Sitzungsb. 1866. Vol. LIV, Pt. I, p. 75.
*Waller, A.*, Microscopic examination of the principal tissues of the
tongue, etc. Phil. Mag. 1846, pp. 273–290.
*Waller, A.*, On the development of the mouth and tongue of the frog.
Phil. Mag. 1850. Vol. I, pp. 38–43.
*Zeller, A.*, Die Abscheidung des indig.-schwefelsauren Natrons
in den Drüsen (Intermaxillary gland). Virchow’s Arch. 1878.
Vol. LXXIII, p. 257.
THE OESOPHAGUS AND STOMACH.
*Biedermann*, Untersuchungen über Magenepithel. Wiener Acad.
Sitzungsb. 1875. Vol. LXXI, Pt. III, p. 377.
*Bischoff*, Ueber den Bau der Magenschleimhaut. Arch. f. Anat. u.
Physiol. 1838, p. 503.
*Bleyer, E.*, Magenepithel und Magendrüsen der Batrachier. Dissert.
Königsberg, 1874.
*Braun*, Zum Vorkommen von Flimmerepithel im Magen. Zool. Anzeiger.
1880. No. 69, p. 568.
*Brinton*, in Cyclopaedia of Anat. and Physiol., edited by R. B.
Todd. 1859. Vol. I, p. 320.
*Cobelli*, Le gliandole acinose del cardia. Wiener Acad. Sitzungsb.
1866. Vol. LIII, Pt. I, p. 251.
*Ebstein, W.*, Beiträge zur Lehre vom Bau und den physiologischen
Funktionen der sogenannten Magenschleimdrüsen. Arch. f. mik. Anat.
1870. Vol. VI, p. 515.
*Ecker, A.*, Ueber die Drüsen der Magenschleimhaut. Zeitsch. f. rat.
Med. 1852, p. 243.
*Foster, M.*, On some points in the epithelium of the frog’s throat.
Journ. of Anat. and Physiol. 1869. Vol. IV, p. 394.
*Frerichs*, On the Stomach, in Wagner’s Handwörterbuch d. Physiol.
1848. Vol. II, p. 748.
*Glinsky, A.*, Zur Kenntniss des Baues der Magenschleimhaut der
Wirbelthiere. Centralbl. f. d. med. Wiss. 1883, p. 225.
*Gonjaew, K.*, Die Nerven des Nahrungsschlauches. Arch. f. mik. Anat.
1875. Vol. XI, pp. 479–496.
*Hebold, O.*, Ein Beitrag zur Lehre von der Sekretion und
Regeneration der Schleimzellen. Dissert. Bonn, 1879, pp. 21–27.
*Heidenhain, R.*, Untersuchungen über den Bau der Labdrüsen. Arch. f.
mik. Anat. 1870. Vol. VI, p. 368.
*Hoffmann, C. K.*, Bronn’s Klassen und Ordnungen des Thierreichs.
Leipzig und Heidelberg. 1873–1878. Vol. VI, pp. 408–412.
*Just, A.*, Zur Histologie und Physiologie des Flimmerepithels.
Breslauer ärztliche Zeitsch. 1885. No. 18, pp. 205–206.
*Klein, E.*, Darmkanal, in Stricker’s Gewebelehre, p. 388, etc.
*v. Kölliker, A.*, Mikroskopische Anatomie, 1854. Vol. II, p. 147.
*Langley, J. N.*, and *Sewall, H.*, On the changes in pepsin-forming
glands during secretion. Journ. of Physiol. 1880. Vol. II,
pp. 261, 281.
*Langley, J. N.*, On the histology and physiology of pepsin-forming
glands. Phil. Trans. 1881. Vol. CLXXII, Pt. III, pp. 663–712.
*Langley, J. N.*, On the structure of secretory cells and on changes
which take place in them during secretion. Internat. Monatschr. f.
Anat. u. Histol. Vol. I, pp. 69–76.
*Leydig*, Lehrbuch der Histologie. 1857.
*Nussbaum, M.*, Ueber den Bau und die Thätigkeit der Drüsen. Arch.
f. mik. Anat. 1882, Vol. XXI, p. 296; 1882, Vol. XXVIII, p. 296;
1877, Vol. XIII, p. 721.
*Partsch, C.*, Beiträge zur Kenntniss des Vorderdarmes einiger
Amphibien und Reptilien. Arch. f. mik. Anat. 1877. Vol. XIV,
p. 179.
*Regéczy, E. N.*, Ueber die Epithelzellen des Magens. Arch. f. mik.
Anat. 1880. Vol. XVIII, pp. 408–411.
*Robinson, C.*, Ueber die Lymphgefässe der Abdominaleingeweide des
Frosches, etc. Froriep’s Notizen, 1846. No. 807, col. 225.
*Rollett*, Bemerkungen zur Kenntniss der Labdrüsen und der
Magenschleimhaut. Untersuch. in d. Institut f. Physiol. u. Histol.
zu Graz. 1871.
*Schultze, F. E.*, Epithel- und Drüsenzellen. Arch. f. mik. Anat.
1867. Vol. III, p. 174; abstract in Centralbl. f. med. Wiss. 1866,
No. 4.
*Schmidt, C.*, Ueber eingenthümliche aus dem Flimmerepithel
hervorgehende Gebilde. Arch. mik. Anat. 1881. Vol. XX, p. 123.
*Sewall, H.*, A note on the processes concerned in the secretion
of the pepsin-forming glands of the frog. Studies in the Biol.
Laborat., Johns Hopkins Univers. Vol. II, pp. 131–134.
*v. Swiecicki, H.*, Untersuchungen über die Bildung und Ausscheidung
des Pepsins bei den Batrachiern. Pflüger’s Arch. f. d. ges.
Physiol. 1876. Vol. XIII, p. 444.
*Trinkler, N.*, Zur Kenntniss des feineren Baues der
Magenschleimhaut, insbesondere der Magendrüsen. Centralbl. f. med.
Wiss. 1883, pp. 161–163.
*Trinkler, N.*, Ueber den Bau der Magenschleimhaut. Arch. f. mik.
Anat. 1885. Vol. XXIV, p. 74.
*Trütschel*, Ueber die Endigung der Nerven in der Schleimhaut des
Magens. Centralbl. f. d. med. Wiss. 1870, p. 115.
*Valatour*, Recherches sur les glandes gastriques et sur les tuniques
musculaires du tube digestif dans les poissons ossieux et les
Batraciens. Annales de Sc. nat. 1861. Series IV. Vol. XVI, p. 219.
THE INTESTINE.
*Arnstein, C.*, Ueber Becherzellen, etc. Virchow’s Arch. 1867.
Vol. XXXIX, p. 527.
*Arnstein, C.*, and *Gonjaew, K.*, Ueber die Nerven des
Verdauungskanals. Pflüger’s Arch. f. d. ges. Physiol. 1874.
Vol. VIII, pp. 614–615.
*Auerbach, L.*, Fernere vorläufige Mittheilung über den Nervenapparat
des Darmes. Virchow’s Arch. 1864. Vol. XXX, p. 457.
*Auerbach, L.*, Untersuchungen über Lymph- und Blutgefässe. Virchow’s
Arch. 1865. Vol. XXXIII, p. 340.
*Auerbach, L.*, Organologische Studien.
*Billroth, T.*, Ueber die Epithelzellen der Froschzunge; der Bau,
Cylinder- und Flimmerepithel und ihr Verhältniss zum Bindegewebe.
Arch. f. Anat. u. Physiol. 1858, p. 159.
*Billroth, T.*, Einige Beobachtungen über das ausgedehnte Vorkommen
von Nervenanastomosen im Tractus intestinalis. Arch. f. Anat. u.
Physiol. 1858, p. 148.
*Brettauer* und *Steinach*, Untersuchungen über das
Cylinderepithelium. Wiener Akad. Sitzungsb. 1857. Vol. XXIII,
p. 303. Moleschott’s Zeitsch. 1857. Vol. III, p. 157.
*Darsch, O.*, Beiträge zur Kenntniss des feineren Baues des
Dünndarms. Wiener Sitzungsb. 1880. Vol. LXXXII, Pt. III, p. 168.
*Dönitz*, Ueber die Schleimhaut des Darmcanals. Arch. f. Anat. u.
Physiol. 1864, p. 367.
*Dönitz*, Ueber Darmzotten. Arch. f. Anat. u. Physiol. 1866, p. 757.
*Eberth, C. J.*, Ueber den feineren Bau der Darmschleimhaut. Würzb.
naturw. Zeitschr. 1864. Vol. V, p. 23.
*Eimer, T.*, Zur Fettresorption, etc. Virchow’s Arch. 1867.
Vol. XXXVIII, p. 428.
*Eimer, T.*, Ueber Becherzellen. Virchow’s Arch. 1868. Vol. XLII,
p. 490.
*Eimer, T.*, Zur Geschichte der Becherzellen. Dissert. 1867.
*Eimer, T.*, Die Wege des Fettes in der Darmschleimhaut bei seiner
Resorption. Virchow’s Arch. 1869. Vol. XLVIII, p. 119.
*Eimer, T.*, Zur Becherfrage. Virchow’s Arch. 1867. Vol. XL, p. 282.
*Erdmann*, Die Resorptionswege in der Schleimhaut des Dünndarms.
Dissert. Dorpat, 1867.
*Fries, E.*, Ueber die Fettresorption und die Entstehung der
Becherzellen. Virchow’s Arch. 1867. Vol. XL, p. 519.
*Gerlach, L.*, Ueber den Auerbachschen Plexus mysentericus. Arbeiten
aus d. physiol. Anstalt. Leipzig. 1872, pp. 102–112.
*Gonjaew, K.*, Die Nerven des Nahrungsschlauches. Arch. f. mik. Anat.
1875. Vol. XI, pp. 479–496.
*Gruby* and *Delafond*, Résultats des recherches faites sur
l’anatomie et les fonctions des villosités intestinales, etc.
Compt. rend. 1843. Vol. XVI, p. 1194.
*Grugenhagen, A.*, Ueber Fettresorption und Darmepithel. Arch. f.
mik. Anat. 1887. Vol. XXIX, p. 139.
*Heidenhain, R.*, Die Absorptionswege des Fettes. Moleschott’s
Untersuchungen. 1858. Vol. IV, p. 251.
*Henle, J.*, Symbolae ad anatomiam villorum intestinalium impr. eorum
epithelii et vasorum lacteorum. Berolini, 1837.
*Hoffmann, C. K.*, Bronn’s Klassen und Ordnungen des Thierreichs.
Leipzig und Heidelberg, 1873–1878. Vol. VI, pp. 412–424.
*Klein, E.*, Der Darmkanal in Stricker’s Gewebelehre, Article XVI.
*Klein, E.*, Contributions to the anatomy of Auerbach’s Plexus in the
intestine of the frog and toad. Quart. Journ. Micros. Sci. 1873.
Vol. XIII, p. 377.
*Klein, E.*, and *Verson, E.*, Der Darmcanal, in Stricker’s
Gewebelehre, 1871, p. 355.
*Klein, E.*, Der neue Nervenapparat v. Thanhoffer’s. Centralbl. f. d.
med. Wiss. 1883, p. 82.
*v. Kölliker, A.*, Nachweis eines besonderen Baues der Cylinderzellen
des Dünndarms. Verhandl. d. phys.-med. Gesells. Würzburg, 1856.
Vol. VI, p. 153.
*v. Kölliker, A.*, Handbuch der Gewebelehre.
*Lambl*, Ueber die Epithelialzellen der Dünndarmschleimhaut. Wiener
med. Wochenschr. 1859. Nos. 24 and 25.
*Langer, C.*, Ueber das Lymphgefässsystem des Frosches. Wiener Acad.
Sitzungsb. 1866. Vol. LIII, Pt. I, p. 395.
*Letzerich, L.*, Ueber die Resorption der verdauten Nährstoffe im
Dünndarm. Virchow’s Archiv. 1866, Vol. XXXVII, p. 232; 1867,
Vol. XXXIX, p. 435.
*Lipsky, A.*, Beitrag zur Kenntniss des feineren Baues des
Darmcanals. Wiener Akad. Sitzungsb. 1865. Vol. LV, Pt. I, p. 183.
*Oeffinger*, Einige Bemerkungen über die sogenannten Becherzellen.
Arch. f. Anat. u. Physiol. 1867, p. 337.
*Partsch, C.*, Beiträge zur Kenntniss des Vorderdarmes einiger
Amphibien und Reptilien. Arch. f. mik. Anat. 1877. Vol. XIV,
p. 179.
*Remak, R.*, Ueber peripherische Ganglien an den Nerven des
Nahrungsrohrs. Arch. f. Anat. u. Physiol. 1858, p. 189; also in
Zeit. d. Vereins f. Heilkunde in Preussen. 1840.
*Renzoni*, Osservazioni e ricerche sul epitelio intestinale.
Rendiconti dell Acad. di Napoli. 1868.
*Rusconi*, Riflessioni sopra il sistema linfatico dei rettili. Pavia,
1845.
*Sachs, J.*, Zur Kenntniss der sogenannten Vacuolen oder Becherzellen
im Dünndarm. Virchow’s Arch. 1867. Vol. XXXIX, p. 493.
*Schultze, F. E.*, Das Drüsenepithel der schlauchförmigen Drüsen des
Dünn- und Dickdarms und die Becherzellen. Centralbl. f. d. med.
Wiss. 1866, p. 160.
*Schultze, F. E.*, Epithel- und Drüsen-Zellen. Arch. f. mik. Anat.
1867. Vol. III, p. 145.
*Thanhoffer, L.*, Beiträge zur Fettresorption und histologischen
Structur der Dünndarmzotten. Pflüger’s Arch. f. d. ges. Physiol.
1874. Vol. VIII, pp. 391–443.
*v. Thanhoffer, L.*, Ein neuer Nervenapparat im Dünndarm. Centralbl.
f. d. med. Wiss. 1883, p. 33.
*v. Thanhoffer, L.*, Antwort auf Herrn Prof. Klein’s ‘Der neue
Nervenapparat etc.,’ betitelte Bemerkungen. Centralbl. f. d. med.
Wiss. 1883, p. 176.
*Valatour, M. M.*, Recherches sur les glandes gastriques et sur les
tuniques musculaires du tube digestif dans les poissons et les
Batraciens. Annales des Sci. nat. 4th Series, Vol. XVI. Zool.
1861, pp. 219–285.
*Watney, H.*, The minute anatomy of the alimentary canal. Phil.
Trans. 1877. Vol. CLXVI, Pt. II, p. 451.
*Wiegandt*, Untersuchungen über das Dünndarmepithel. Dissert. Dorpat,
1860.
*v. Wittich*, Beiträge zur Frage über Fettresorption. Virchow’s Arch.
1857. Vol. XI, p. 37.
THE LIVER, GALL-BLADDER, AND PANCREAS.
*Barfurth, D.*, Vergleichend-histochemische Untersuchungen über das
Glycogen. Arch. f. mik. Anat. 1885. Vol. XXV, p. 369.
*Brotz, J.*, and *Wagenmann, C. A.*, De amphibiorum hepate et
glandularum ductu excretio carentium structura deque earundem
functionibus experimenta. Berolini, 1841.
*v. Brunn, A.*, Flimmerepithel in den Gallengängen des Frosches.
Zool. Anzeiger. 1883. No. 148, p. 483.
*Eberth, C. J.*, Die Pigmentleber der Frösche und die Melanämie.
Virchow’s Arch. 1867. Vol. XL, p. 305.
*Eberth, C. J.*, Zur Kenntniss der Verbreitung glatter Muskeln.
Zeitschr. f. wiss. Zool. 1863. Vol. XII, p. 360.
*Eberth, C. J.*, Ueber den feineren Bau der Leber. Centralbl. f. d.
med. Wiss. 1866, p. 897.
*Eberth, C. J.*, Untersuchungen über die Leber der Wirbelthiere.
Arch. f. mik. Anat. 1867. Vol. III, p. 423.
*Eberth, C. J.*, Untersuchungen über die normale und pathologische
Leber. Virchow’s Arch. 1867. Vol. XXXIX, p. 70.
*Eberth, C. J.*, Ueber die Pigmentleber der Frösche. Virchow’s Arch.
1862. Vol. XXIX, p. 70.
*Gerlach, L.*, Ueber die Nerven der Gallenblase. Centralbl. f. d.
med. Wiss. 1873, p. 562.
*Hering, E.*, Ueber den Bau der Wirbelthierleber. Wiener Acad.
Sitzungsb. 1886. Vol. LIV, Pt. I, p. 335.
*Hering, E.*, Ueber den Bau der Wirbelthierleber. Arch. f. mik. Anat.
1867. Vol. III, p. 88.
*Hering, E.*, On the liver. Stricker’s Gewebelehre. 1872, p. 429.
*Hoffmann, C. K.*, Bronn’s Klassen und Ordnungen des Thierreichs.
Leipzig und Heidelberg, 1873–1878. Vol. VI, p. 424.
*Jones, C. H.*, On the structure and development of the liver. Phil.
Trans. 1849. Pt. I, p. 122.
*Langley, J. N.*, On variations in the amount and distribution of fat
in the liver-cells of the frog. Proc. Roy. Soc. 1886. Vol. XXXIX,
p. 234.
*Leydig, F.*, Lehrbuch der Histologie. 1857.
*Leydig, F.*, Die Leber der Fische und Batrachier.
*Nussbaum, M.*, Ueber den Bau und die Thätigkeit der Drüsen
(Pancreas). Arch. f. mik. Anat. 1877. Vol. XIII, p. 752.
*Popoff, M.*, The nerves of the gall-bladder (in Russian). Rudneff’s
Journ. f. normal. u. pathol. Histol., etc. 1872.
*Remak, R.*, Ueber runde Blutgerinnsel und über pigmenthaltige
Zellen. Arch. f. Anat. u. Physiol. 1852, p. 115.
*Weber, E. H.*, Ueber die periodische Farbenänderung welche die Leber
der Hühner und Frösche erleidet. Bericht von Verhandl. K. Säch
Gesell. Leipzig, 1850, p. 15.
*Zeller, A.*, Die Abscheidung des indig.-schwefelsauren Natrons in
den Drüsen (Pancreas). Virchow’s Arch. 1878. Vol. LXXIII, p. 257.
THE SPLEEN.
*Billroth, T.*, Beiträge zur vergleichenden Anatomie der Milz. Arch.
f. Anat. u. Physiol. 1857, p. 88.
*Billroth, T.*, Beiträge zur vergleichenden Anatomie der Milz.
Virchow’s Arch. 1861, Vol. XX, p. 410, and 1862, Vol. XXIII,
p. 457; also Zeitschr. f. wiss. Zool. 1862, Vol. XI, p. 325.
*Ecker*, Blutgefässdrüsen, in Wagner’s Handwörterbuch der
Physiologie. 1849. Vol. IV.
*Gray, H.*, On the structure and use of the spleen. London, 1854.
*Hoffmann, C. K.*, Bronn’s Thierbuch. Leipzig und Heidelberg,
1873–1878. Vol. VI, p. 509.
*v. Kölliker, A.*, Ueber den Bau und die Verrichtungen der Milz.
Mittheil. d. naturf. Gesell. in Zürich, 1847. Vol. I, p. 120.
*Kusnezoff, F.*, Ueber blutkörperchenhaltige Zellen der Milz. Wiener
Sitzungsber. 1873. Vol. LXVII, Pt. III, pp. 58–67.
*Müller, W.*, Ueber den feineren Bau der Milz. Leipzig und
Heidelberg, 1865.
*Remak, R.*, Ueber runde Blutgerinnsel und über pigmenthaltige
Zellen. Arch. f. Anat. u. Physiol. 1852, p. 115.
*Schweigger-Seidel, F.*, Untersuchungen über die Milz. Virchow’s
Arch. 1862. Vol. XXIII, p. 526.
*Stieda, L.*, Zur Histologie der Milz. Dorpat, 1862.
THE PERITONEUM.
*Alltmann, R.*, Ueber die Veränderungen des serösen Epithels am
blosgelegten Froschmesenterium. Arch. f. mik. Anat. 1878.
Vol. XVI, p. 111.
*Arnold, J.*, Ueber die Durchtrittsstellen der Wanderzellen durch
entzündete seröse Häute. Virchow’s Arch. 1878. Vol. LXXIV, p. 245.
*Batelli, A.*, Dello addaltamento di alcune cellule endotiali nelle
membrane serose. Lo Sperimentale. 1884, p. 132.
*Cyon*, Ueber die Nerven des Peritoneum. Bericht über d. Verhandl.
d. Kön. Säch. Gesell. d. Wiss. z. Leipzig, 1868. Vol. XX, p. 119.
Leipzig, 1869.
*Grunau, H.*, Ueber das Flimmerepithel auf dem Bauchfell des
weiblichen Frosches und über den Eileiterbau desselben. Dissert.
Königsberg, 1875.
*Hoffmann, C. K.*, Bronn’s Klassen und Ordnungen des Thierreichs.
Leipzig und Heidelberg, 1873–1878. Vol. VI.
*Hoffmann, T.*, Die Lungen-Lymphgefässe der Rana temporaria. Dissert.
Dorpat, 1875.
*Kapff*, Untersuchungen über das Ovarium und dessen Beziehungen zum
Peritoneum. Arch. f. Anat. u. Physiol. 1872, p. 553.
*Klein, E.*, On Remak’s ciliated vesicles and corneous filaments of
the peritoneum of the frog. Quart. Journ. Mic. Sci. New Series,
1872. Vol. XII, p. 43.
*Klein, E.*, On the peripheral distribution of non-medullated
nerve-fibres (nerves of the peritoneum). Quart. Journ. Micros.
Sci. 1872. Vol. XII, p. 32.
*Leydig*, Lehrbuch der Histologie. 1857, p. 325.
*Mayer*, Ueber die Flimmerbewegung. Froriep’s Notizen, 1836.
Vol. XLVII, p. 179.
*Neumann, E.*, Die Beziehungen des Flimmerepithels der Bauchhöhle zum
Eileiterepithel beim Frosch. Arch. f. mik. Anat. 1875. Vol. XI,
pp. 354–377.
*Nicolsky, P.*, Ueber das Flimmerepithel beim Frosche. Centralbl. f.
d. med. Wiss. 1880, p. 641.
*Paladino, G.*, Dell’ endotelio vibratile nei Mammiferi ed in
generale di alcuni dati sulla fisiologia delle formazioni
endoteliche. Estr. dal Giornale intern. delle Scienze Mediche.
1882. Vol. IV.
*Schweigger-Seidel* and *Dogiel*, Ueber die Peritonealhöhle der
Frösche. Arbeiten aus d. physiol. Anstalt zu Leipzig. 1866, p. 68.
*Solger, B.*, Ueber einige Entwicklungsstadien des Peritonealepithels
der Amphibien-larven. Manusc. d. Naturf. Versamml. zu Freiburg.
1884.
*Thiry*, Ueber das Vorkommen eines Flimmerepitheliums auf dem
Bauchfell des weiblichen Frosches. Göttinger Nachrichten. 1862,
pp. 171–174.
*Tourneux*, Recherches sur l’épithelium des sereuses. Journ. de
l’anat. et de la physiol. 1874.
*Waldeyer*, Eierstock und Ei. Leipzig, 1870, pp. 72 and 122.
*Wolff, W.*, Ueber freie sensible Nervenendigungen. Arch. f. mik.
Anat. 1882. Vol. XX, pp. 377–381.
THE ALIMENTARY TRACT, ETC.
I. THE ALIMENTARY TRACT.
The alimentary tract consists of the mouth or pharyngo-oral cavity, the
oesophagus, the stomach, the small intestine and the large intestine;
these together forming a tube extending from the mouth to the cloaca.
From the commencement of the oesophagus, at the entrance to the larynx,
to the end of the cloaca, the length of the tube is about 31.5 cm.,
that of the various parts being:
From glottis to pylorus 5.5 cm.
From pylorus to large intestine 22.0 cm.
Large intestine to end of cloaca 4.0 cm.
--------
Total length 31.5 cm.
========
A. The *Mouth*.
The mucous membrane covering the tongue will be described with the
sense-organs (see organ of taste).
*a.* *General description.* The mouth of _R. esculenta_, as in all
other amphibia, with the exception of the lowest (_Siren_, _Proteus_,
etc.), is of considerable width, and extends backwards as far as
the middle of the tympanic membrane. The upper margin of the mouth
possesses a lip or fold of the skin (_SS^{1}_), which projects
sufficiently to prevent the teeth being seen from the front or from
the sides. This lip-like rim is most prominent in the premaxillary and
superior maxillary regions, but can be traced along the whole length of
the upper jaw, and on to the lower jaw, by means of a well-marked fold
at the angle of the mouth. Beyond this point the lip is absent, as the
skin is closely attached to the bony mandible.
On the *roof* of the *mouth* the following structures can be made out:
immediately within the lip is a deep, well-marked groove, the outer
boundary formed by the lip, the inner by a fold of the mucous membrane
(Fig. 178 _F_); this fold increases from behind forwards as far as the
premaxillary bones, where it forms two prominences (_F^1_, _F^1_) with
an interval between. These correspond to the palatine processes of the
premaxillary bones: immediately behind them are openings of the ducts
of the intermaxillary glands. In the groove so formed are placed a
single row of simple teeth, which, though subject to many variations,
are usually about fifty in number.
[Illustration: Fig. 178.
The roof of the mouth.
_Cho_ Posterior naris.
_ID_ Opening of intermaxillary glands.
_F_ Fold of mucous membrane.
_F^1_, _F^1_ Prominences of mucous membrane.
_K_ Muscles.
_O_ Floor of the orbit.
_S_ Lip.
_S^1_ Lip.
_T_ Eustachian tubes.
_Vo_ Vomer.
]
A little further back and to either side of the median line is a small
group of vomerine teeth (_Vo_); each group has from five to ten teeth;
external to these is on each side a transversely-placed oval opening,
the posterior nares (_Cho_). These apertures are directed outwards and
backwards into a shallow groove, bounded anteriorly by a fold of mucous
membrane.
According to Wiedersheim the mucous membrane immediately around the
vomerine teeth is supplied with taste-bulbs; the epithelium surrounding
these being non-ciliated.
The roof of the mouth underneath the parasphenoid is somewhat vaulted
and on either side depressed by the eyeballs, which project downwards
more or less prominently (_O_, _O_). Still further back are the
openings of the Eustachian tubes (Fig. 178 _T_), one on each side, and
almost surrounded by the limbs of the pterygoid bones.
On the *floor* of the *mouth* (Fig. 179) the tongue (_Z_, _Z^1_)
forms the most prominent object; its shape varying according to the
state of contraction of its muscles. Behind it, in the middle line,
is a transverse groove (†), corresponding to the posterior border of
the hyoid bone, and still further back is the opening to the larynx
(_L_), a longitudinal slit about 3 mm. in length. The mucous membrane
to either side of the tongue is only slightly folded, and a little
in front of the angle of the mouth is depressed into an aperture
(_S_), opening into the vocal sac. This opening is surrounded by small
radiating folds of mucous membrane, and is oval in shape.
[Illustration: Fig. 179.
The floor of the mouth.
_K_ Muscles.
_L_ Opening to larynx.
_M_ Mandible.
_S_ Opening to voice-sac (in males only)
_Sm_ Chin.
_Z_ Tongue.
_Z^1_ Left cornu of bifid tongue.
† Folds opposite hinder border of the hyoid.
]
Towards the oesophagus the mucous membrane of both the roof and the
floor of the mouth is thrown into numerous longitudinal folds.
*b.* The *minute structure* of the several parts.
(1) The *mucous membrane* of the mouth. At the junction of the skin and
the mucous membrane there is a gradual transition from the stratified
epithelium of the skin to a single layer of *columnar epithelium*. On
the floor of the mouth this condition is reached at the tongue; on the
roof the transition takes place more quickly. The columnar epithelium
of the mouth (that of the tongue is excluded from this description) is
ciliated; scattered cells, which are not ciliated, are found here and
there irregularly, but are not numerous. The cylindrical cells are very
finely granular in their upper parts, clearer in the middle portion,
more coarsely and darkly granular in their deeper portions; each cell
is possessed of a large, well-defined, oval nucleus, which contains one
or sometimes two nucleoli. The non-ciliated cells usually present a
sharply differentiated, structureless, hyaline, free border (Schultze).
The epithelium towards the margin of the mouth, where it is stratified,
is also ciliated.
Goblet-cells occur in every part of the epithelium, whether ciliated or
non-ciliated, and their forms vary very greatly.
[The *submucous layer* is a fibrous connective-tissue matrix, very rich
in nerves and blood-vessels. The capillaries are arranged in small,
somewhat polygonal meshes (Fig. 180), and are peculiar, with those of
the anterior part of the oesophagus, in having small dilatations. This
arrangement was first[71] described by Langer, and later by Schöbl. The
dilatations are placed quite irregularly on the capillaries, sometimes
only on one side, sometimes on both sides of the vessel; a slight
constriction occurs at the neck of each dilatation, where it opens
into the capillary[72]. The nerves of the mucous membrane underneath
the orbits have nerve-cells attached to them (Stirling and Macdonald,
page 170). The lymphatics are very numerous, and for the most part
follow the course of the blood-vessels to their finest twigs, beyond
which they follow an independent course (Langer).]
[Footnote 71: Beale, Phil. Trans., 1863, p. 153, shows dilatations in
his drawing, but makes no reference to them in the text.]
[Footnote 72: The vascular supply of the mucous membrane of the dorsal
surface of the mouth and oesophagus is shown (after Schöbl) in Plate
II, Fig. 180, I. Arteries red, veins blue. II. in the same figure
represents the dilatations on the capillaries; after Schöbl.]
(2) The *teeth* are wanting in the lower jaw; on the roof of the mouth
they are found in two situations: as a single row in the groove within
the lip, and a group on each vomer. Each tooth has the form of an
elongated cone, which in the case of the jaw-teeth is curved, in that
of the vomerine teeth straight. The teeth are fixed to the jaw so as to
project upwards and slightly inwards, those at the front of the mouth
projecting backwards, and those on the vomers project backwards. Each
tooth has a small, sharp projection, or secondary crown on its outer
surface (Fig. 181), placed near the mucous membrane. The teeth are
fixed to the bones by means of _Crusta petrosa_, which is again united
to the bones of the mandible by a matrix of spongy bone, continuous
for the several teeth. Between the tooth and the mucous membrane is a
layer of flattened epithelium (_II_), which extends more deeply on the
inner side of the tooth than on the outer; the layer is continuous with
the epithelium of the mouth, and is two to three cells in thickness.
Each tooth has fine longitudinal grooves on the basal part of its
outer surface, and consists of two parts, a crown and a root. The
teeth possess large cavities, the wall being thin and almost of even
thickness, except on the inner surface of the basal portion of the
root, where the wall is wanting, and so forms a large aperture to the
root.
The general skeleton of the tooth is formed of dentine, this is covered
on the crown by a layer of enamel, and the _Cuticula dentis_ on the
socket by a layer of _Crusta petrosa_.
α. The *dentine* is a homogeneous substance pierced by numerous
tubules (_D_), which arise at the pulp-cavity and course in a parallel
direction to the surface of the dentine, where they form a rich
network with irregular, interglomerular spaces. The inner surface of
the dentine is rough, through the presence of numerous small, dark
tubercles.
β. The *enamel* covers the dentine on the apical portion of the tooth.
It has tubes coursing through it, which are continuous with those of
the dentine, and presents also circumferential striations (Fig. 181
III).
[Illustration: Fig. 181.
I. Transverse section of the premaxillary bone to show attachment of
the teeth; after Hertwig. Magnified 22 times.
II. Dentine and enamel; after Hertwig. Magnified 500 times.
III. Enamel: after Hertwig. Magnified 500 times.
_A_ Blood-vessel of the pulp-cavity.
_C_ Crusta petrosa.
_D_ Dentine.
_F_ Processus dentalis.
_H_ Layer of epithelium.
_O_ Tooth cuticle.
_R_ Reserve.
_S_ Enamel.
_X_ Cutaneous glands.
]
γ. The *tooth cuticle* (_Cuticula dentis_) is colourless and covers the
enamel. It is highly refractive, very transparent, and very resistant
to chemical reagents. From the apex, towards the _Crusta petrosa_,
it thins very rapidly, but is continued sufficiently far to cover a
portion of the _Crusta petrosa_.
δ. The _Crusta petrosa_ resembles bone, except that it contains no
Haversian canals; it possesses cells which resemble bone corpuscles,
and are usually somewhat rounded or oval and communicate with each
other by their processes; for the most part it is homogeneous and free
from cells (Hertwig).
ε. The *pulp-cavity* contains a connective-tissue very rich in cellular
elements; those cells adjacent to the dentine are arranged in a layer
(_Membrana eboris_) which has somewhat the appearance of a layer of
epithelium. The cells (odontoblasts) of this layer are spindle-shaped,
and send processes (dentinal fibres) into the dentinal tubules. A small
blood-vessel can be traced into each cavity, but as yet no nerve has
been found in the pulp-cavities.
[Smith (_l. c._) has, after careful investigation, come to the
conclusion that the teeth of _R. esculenta_ and _R. temporaria_ are
practically alike, therefore the methods of differentiating the two
species by means of the teeth, as given by Leydig, are not to be relied
on.]
(3) The *intermaxillary glands* (_Glandula intermaxillaris_) consist
of a mass of convoluted tubes, lying chiefly between the premaxillary
bones and the capsule of the nose, and opening by about twenty to
twenty-five ducts at the fore-part of the mouth (Fig. 178 _ID_). A
portion of the glands extends high into the nasal cavity (Born), while
dorsally another portion lies under the skin and the _M. dilatator_
and _M. lateralis narium_, which together act as compressors to the
subjacent glands: a small, elastic, cartilaginous rod, placed between
the anterior margin of the nasal capsule and the under surface of the
ascending limb of the premaxilla, opposes these muscles on either side
by its spring-like action (Wiedersheim).
In a fresh skull the openings of the ducts can easily be seen after
washing away the mucous secretion; they are, however, seen to better
advantage by treatment with Müller’s fluid and subsequent staining with
carmine. With sufficient magnifying power, they are then seen as a row
of bright dots. The tubules are of uniform thickness, placed closely
side by side, and surrounded by a nervous plexus, which contains
numerous branching nerve-cells. The epithelium of the tubules is
cylindrical, with a rounded, finely granular nucleus; processes from
the peripheral ends of the cells are continued to a _Membrana propria_.
The ducts are lined with columnar, ciliated epithelium.
The *secretion* of the glands is remarkably adhesive, and is wiped off
by the tongue when it is projected; by this means the tongue becomes a
particularly efficacious instrument for capturing prey. The glands are,
both histologically and chemically, pure mucous glands. In urodeles the
homologous glands are placed in the hollow septum of the nose, between
the nasal cavities.
(4) The *tongue* (Figs. 179, 182, 183) is a broad, fleshy flap on the
floor of the mouth, to which it is attached by the anterior half of its
ventral surface as far forwards as the chin. Seen from above it has a
wedge-like form, being narrow in front and wider behind, where it is
prolonged at each angle to form two cornua.
By raising the tongue one obtains a view of a portion of the _M.
hyoglossus_. The two _MM. hyoglossi_ arise (see page 66) some distance
apart, and run forwards and towards each other to meet on the ventral
surface of the hyoid bone; they now assume a longitudinal direction,
and course forwards parallel to each other until they reach the _M.
genio-glossus_ (Fig. 182 _G_). Each muscle now divides to form coarse
bundles, which ascend on either side of the _M. genio-glossus_ towards
the dorsum of the tongue. In this course they are encircled by a
strong, elastic, connective-tissue sheath. The sheath is incomplete at
the hinder end of the _M. genio-glossus_, where it possesses rounded
apertures, through which the glossopharyngeal nerves (_N_, _N_)
disappear, to be distributed, after a sharp curve backwards, in the
substance of the organ.
The _M. genio-glossus_ arises, in two parts on either side, at the side
of the chin. One part (Fig. 182 _G_) is dorsal and median, the other
(Fig. 182 _G^1_) ventral and external.
[Illustration: Fig. 182.
Muscles of the tongue, seen from the ventral surface.
_G_ Median portion of M. genio-glossus.
_G^1_ Lateral portion of M. genio-glossus.
_H_ Hyoid.
_Hy_ M. hyoglossus.
_L_ Larynx.
_M_ Mandible.
_N_ Glossopharyngeal nerve.
]
The first part, with its fellow of the opposite side, forms an arched
commissure in the form of muscular rings, which decrease in size
from before backwards, and so form a pear-shaped mass: the second,
external portion, extends backwards, with a slight obliquity, as a
thin, fan-like expansion, to the mucous membrane, where it is inserted.
This arrangement can easily be seen after dissecting away the sheath
(Fig. 183 _Hy_); the hindermost fibres curve sharply into the tongue
(_Hy^1_); the anterior fibres pass obliquely forwards and blend with
the straight fibres of the dorsal portion of the _M. genio-glossus_
(Fig. 183 _Gg_). The arcuate fibres of the _M. genio-glossus_ pass,
for the most part, upwards and outwards to the tips of the posterior
bifid border of the tongue; in this course they lie as a rule above the
_M. hyoglossus_, but here and there the two muscles intermix (Fig. 183
_Gg^1_), and it is by no means easy to separate them.
The _M. hyoglossus_ is the retractor of the tongue, the _M.
genio-glossus_ the protractor.
(For mucous membrane of the tongue, see organ of taste. The vocal sacs
are described with the organs of voice and respiration.)
B. The *Oesophagus* and *Stomach* (Figs. 184, 185, 189, 194, 195, 199).
*a.* *General description.* The oesophagus is not separated from the
pharyngo-oral cavity by a sharp line of demarcation. It has a length of
only a few mm. in medium-sized frogs (Fig. 184 _Oe_), and lies in the
middle line of the body, supported on either side by the cornua of the
hyoid bone. The oesophagus lies on the dorsal wall of the larynx, is
smooth externally, and is thrown into well-marked longitudinal folds
internally.
[Illustration: Fig. 183.
Muscles of the tongue, from the ventral surface.
_G_ M. genio-glossus.
_Gg_ Straight fibres of the M. genio-glossus.
_Gg^1_ Curved fibres of the M. genio-glossus.
_Hy_ and _Hy^1_ M. hyoglossus.
_Z_ Borders of the tongue.
]
The transition from oesophagus to stomach is somewhat indefinitely
marked by a slight dilatation of the tube, often scarcely perceptible,
still it can always be recognized by an abrupt curvature to the left
(Fig. 184 _M_), which becomes more prominent when the stomach is
distended. Externally the stomach is seen as an elongated, slightly
curved cone, smooth externally and of equal diameter throughout.
The oesophagus and stomach are held in position by folds of peritoneum
(mesentery), which attaches them to the dorsal wall of the abdominal
cavity, to the lungs, pericardium, and liver; and by the blood-vessels.
*b.* *Minute structure.* The walls of these viscera are composed of
four layers or coats.
(1) The *serous coat* (Fig. 186) is a layer of endothelium, lying on
a very thin stratum of connective-tissue; the whole derived from the
peritoneum, which encloses the organs.
(2) The *muscular coat* (Fig. 186 _LM_ and _TM_) is arranged in two
layers, one (_LM_) longitudinal, the other (_TM_) transverse. The
longitudinal layer is thicker in the oesophagus, and thins as it is
continued to the pyloric end of the stomach. The circular layer, on the
other hand, gains in thickness; both layers are of unstriated muscular
fibre.
[Illustration: Fig. 184.
The alimentary canal.
_A_ Opening of large intestine into cloaca.
_Cl_ Cloaca.
_D_ Small intestine.
_Du_ Duodenum.
_HB_ Urinary bladder.
_M_ Stomach.
_Mz_ Spleen.
_Oe_ Oesophagus.
_Py_ Pylorus.
_R_ Large intestine (rectum).
† Junction of small and large intestine.
]
(3) The *submucous coat* (Fig. 186 _A_, _B_, and _SM_) is better
developed in the stomach than in any other part of the alimentary
canal. It is formed of a wide-meshed, loose connective-tissue, which
supports numerous blood-vessels and lymphatics. Towards the mucous
coat it possesses a well-differentiated _Muscularis mucosa_, which is
arranged in two layers, a longitudinal (_B_) and a transverse (_A_).
(4) The *mucous coat* is possessed of numerous tubular glands, which
vary in structure according to the part of the membrane examined. They
have been the subject of much investigation (Heidenhain, Nussbaum,
Partsch, Langley, and others), and are best described in three groups:
those of the oesophagus, of the first part of the stomach, and of the
pyloric end of the stomach respectively; between each pair of groups
are transitional forms.
α. [The oesophageal glands are complete tubular glands lined by a
single layer of epithelium, which very closely resemble the glandular
cells of the fundus of the stomach (Plate II, Fig. 187). The cells
are conical or cylindrical, the protoplasmic contents granular, the
granules being larger than those of the corresponding cells in the
stomach (Langley). Mucous cells are found among the true secretory
cells. The cells of the ducts are sometimes, but rarely, ciliated
(Langley).]
[Illustration: Fig. 185.
The abdominal viscera of _Rana esculenta_ (female).
_D_ Small intestine.
_Du_ Duodenum.
_EE_ Ovaries.
_H_ Heart.
_HB_ Urinary bladder.
_L_ Left lobe of liver.
_L^1_ Right lobe of liver.
_L^2_ Middle lobe of liver.
_Lg_ Left lung.
_Lg^1_ Right lung.
_M_ Stomach.
]
β. [The glands of the fundus of the stomach[73] are not so complex as
the typical glands of the oesophagus. The cells at the mouth of the
gland are continued into fine processes (Fig. 187), and their outer
parts contain mucigen. The cells of the neck of the gland are more
cubical, and towards the lower part of the neck are mucous cells. The
cells of the body of the gland are of irregular shape, and so placed
that the nucleus of one cell faces the junction of two cells on the
opposite side (Langley). These cells are very finely granular.]
[Footnote 73: A transverse section through the mucous membrane of
the fundus of the stomach of _Rana esculenta_ is shown in Plate II,
Fig. 187. Alcohol preparation, doubly stained with carmine and anilin
blue. After Biedermann. (Obj. II, Syst. 7, Hartnack.)]
[Illustration: Fig. 186.
Transverse section through one of the longitudinal folds of stomach of
_Rana temporaria_. To show general arrangement of the walls.--G. H.
_A_ Transverse layer of muscularis mucosae.
_B_ Longitudinal layer of muscularis mucosae.
_LM_ Longitudinal muscular coat.
_M_ Mucous membrane.
_SM_ Submucous coat.
_TM_ Transverse muscular coat.
]
γ. [The glands of the pyloric end of the stomach have been compared
with the mouths and necks of the glands of the fundus (Partsch,
Langley). The cells are of two kinds only (Fig. 188). The cylindrical
cells of the surface of the stomach are continued into the gland, where
they become shorter and sub-cubical; these form the greater part of the
gland. The cells at the deepest portion of the gland are more rounded,
and resemble the mucous cells in the neck of the glands of the fundus.]
δ. [Between these well-marked groups of glands are various transitional
forms. The transition from oesophageal to gastric glands is not a
continuous one, as glands resembling those of the stomach can be found
nearer the oesophagus than other glands, which more nearly resemble
oesophageal glands. At the same point the mucous membrane is thinner
than either in front or behind. In the same way an intermediate zone
exists between the typical glands of the fundus and pylorus of the
stomach.]
In both oesophagus and stomach the mucous membrane is thrown into
longitudinal folds when the organs are empty. The epithelium of the
surface of the oesophagus is mostly ciliated, and possesses numerous
goblet-cells; according to Klein the cells are not set vertically on
the subjacent submucosa, but obliquely.
[The epithelium of the surface of the stomach is, at least in part,
ciliated (Regéczy, Trinkler, and others), and has numerous goblet-cells
(Schultze, Heidenhain, Bleyer, Eimer, Oedmonson, and others).]
[Illustration: Fig. 188.
Transverse section through the mucous membrane of the pyloric end of
the stomach of _Rana esculenta_. After Partsch. (Obj. II, Syst. 7,
Hartnack.) ]
(5) [The *nerves* of these organs, according to Gonjaew, contain both
medullated and non-medullated fibres, which have nerve-cells attached
to them. From these fine branches pass, either with the blood-vessels
or alone, to the mucous coat, losing their medulla on the way. In this
course they inosculate very freely, and are then distributed as very
fine, beaded fibrils to the glands and epithelium, which are very
richly supplied.]
(6) [The *blood-vessels* and *lymphatics* very closely resemble
the corresponding structures in the small intestine (p. 290); the
blood-vessels form a rich anastomosis in the submucous membrane; the
lymphatics are arranged in two systems, one under the serous coat, and
a larger system in the mucous and submucous coats. The oesophagus lies
free in a peri-oesophageal lymph-sac (Robinson).]
C. The *Small Intestine*.
*a. General description.* The small intestine commences behind the
middle of the abdomen at the pyloric end of the stomach, from which it
is marked off by a slight constriction. The first portion of the small
intestine is the duodenum (Figs. 184 and 194 _Du_); by means of an
abrupt turn it winds directly forwards, parallel to the long axis of
the stomach; the pancreas is placed in the loop so formed.
The whole of this portion of the intestine, together with the greater
part of the stomach, is, in the normal condition, under cover of the
liver (Figs. 185, 194): while under the liver the intestine is firmly
attached to the deep surface of that organ by a short but strong
_Ligamentum hepato-duodenale_; it then turns suddenly backwards,
increases in size, and by means of numerous convolutions occupies a
considerable portion of the right half of the abdomen (Fig. 184 _D_).
It is held in position by a well-developed mesentery.
*b.* *Minute structure.* Like other portions of the alimentary canal,
the small intestine is formed of four layers:--
(1) The *serous coat* presents no peculiarities; it consists simply of
a layer of endothelial cells, with a small amount of sub-endothelial
connective-tissue.
(2) The *muscular coat* is in two layers, the outer longitudinal layer
being very thin, the inner circular layer thick.
(3) The *submucous layer* resembles that of the stomach, but is not so
thick; the _muscularis mucosae_ is well developed and arranged, as in
the stomach, in two layers.
(4) The *mucous coat* (Fig. 189) is thrown into folds, which differ in
various parts of the tube.
The longitudinal folds of the stomach are compressed together towards
the pyloric end of the stomach (_a_) and diminish in size; at the
commencement of the duodenum they end abruptly (_a^1_), but without any
indication of a valvular arrangement.
Immediately beyond the pylorus the mucous membrane is folded so as to
form an irregular network of folds which inclose irregular alveoli;
the folds are thicker on the concave surface of the duodenum, and form
a longitudinal ridge (_b_); in this ridge the alveolar spaces are
much smaller than those to either side. The irregular folding extends
through two to three cm., when a more regular arrangement commences in
the form of two adjacent series of transverse folds (_c, c^1_). Each
fold is semi-lunar in shape, with the convexity attached to the wall
of the tube and directed forwards, while the concave free border and
pocket-like space enclosed are directed backwards.
The arrangement of these folds reminds one of the semi-lunar valves of
the human heart, and probably one of their functions is to prevent the
regurgitation of the chyme (Wiedersheim).
The corresponding valves of opposite sides meet at each end at an
angle, the apex of which is directed away from the stomach. On these
folds and between them are smaller, secondary folds, partly irregularly
arranged, partly longitudinal (_d d_).
Towards the middle of the small intestine this valvular arrangement
is lost, to be replaced by an irregular net-like folding; beyond this
longitudinal folds arise, which proceed in a sinuous course towards the
large intestine.
The whole mucous membrane, both on the folds and otherwise, is covered
with a simple layer of columnar epithelium, which is continued into
numerous simple follicles (glands of Lieberkühn) found throughout
the mucous membrane of the small intestine. The cells are placed
on a basement membrane, which rests on a thin layer of loose
connective-tissue, intervening between the epithelial coat and the
_muscularis mucosae_. The epithelial cells are intermixed with a large
number of goblet-cells, and have between them fine processes from the
connective-tissue corpuscles of the subjacent layer; many of these
processes extend to or even beyond the free margin of the epithelial
cells.
[Illustration: Fig. 189.
Mucous membrane of the pyloric end of the stomach and the duodenum.
_a_ Mucous membrane of the stomach.
_a^1_ Commencement of duodenum.
_b_ Duodenal mucous membrane arranged in irregular network.
_c_ } Semi-lunar folds of
_c^1_} the mucous membrane.
_d_ Longitudinal folds of the mucous membrane.
]
The individual cells are columnar, possessed of a well-marked
cell-wall, and have distinct, large, oval nuclei, containing one
or more nucleoli. The protoplasmic contents are granular, and with
proper treatment show a very distinct intracellular network. The free
margins of the cells are sharply marked off from the cell-contents,
and are more firmly attached to the corresponding portions of adjacent
cells than the rest of the cell-wall. This margin has a longitudinal
striation, which owing to the important function performed by this part
of the intestine, namely, absorption of the fat, has been the subject
of many important investigations.
[In the following brief summary of the earlier researches on
the minute structure of the intestinal epithelium, in which the
intestine of the frog was chiefly used, the memoirs in which these
investigations are recorded are referred to in the order of time.
1837. Henle first described the border as a thickened, highly
refractive portion of the cell-wall.
1855. Kölliker and Funke, after independent research, described the
longitudinal striation: Funke offered no explanation of the fact,
while Kölliker considered it due to the presence of fine tubules.
Later Funke gave a modified support to Kölliker’s view by admitting
the presence of tubules around the circumferential part of the border.
1856. Donders gave a description corresponding with that of Henle.
1857. Brettauer and Steinach gave it as the result of their
investigations that the border was composed of closely-applied fine
rods: v. Wittich first showed that the borders of adjacent cells
were more firmly attached than the rest of the cell; he admitted the
presence of apertures, but considered the whole appearance to be due
to post-mortem changes.
Welcker and Friedreich agreed with the views of Brettauer and
Steinach, but traced the striation throughout the length of the
cells, in fact traced the tubules to the connective-tissue below.
1858. In this year Heidenhain published his results; he held the
striation to be due to the presence of fine rods, and was the first
to show that processes of the connective-tissue corpuscles passed up
between the epithelial cells; he found fat globules in the epithelial
cells, in the connective-tissue, and in the lacteals.
Friedreich described the striation as continued through the whole
length of the cells, and as due to tubules.
1859. Lambl denied the presence of the rods, and considered the whole
phenomenon an optical appearance due to the cell-wall; in this view
he was supported by Vlakovich of Padua and Amici of Florence.
1860. Wiegandt held the border to be an independent covering, and the
striation to be due to folding or wrinkling.
Col. Balogh described the border as formed of rods, but denied that
these existed except when brought about by the action of fats; in
support of this view he showed that the striation was wanting when
fat was absent.
1865. Lipsky held the border to be composed of rods.
1866. Henle described the cells as in his former work, but now held
the border to be composed of rods, in fact to represent a ciliated
border.
1867. Erdmann described the border as being of two layers, an upper,
thicker layer, with both longitudinal and transverse striation,
and a lower, thinner layer, the true cell-wall. The upper layer
he described as capable of splitting in the directions of both
striations.
Schultze described the border as not being in intimate connection
with the protoplasm of the cell. Arnstein and Wiegandt supported
Heidenhain’s description.
1868. Albini e Renzoni described the part as resembling resting cilia.
1869. Eimer traced fat-globules into all the parts, epithelium,
connective-tissue, and vessels; and held that the fat could pass from
a lacteal to a branch of the Vena porta.
1870. Heidenhain, after further investigation, supported his earlier
views.
1874. Thanhoffer described the membrane as perforated, and the
protoplasm of the cells as actively sending protoplasmic processes
through these apertures; this he had seen in frogs in which all
connection with the spinal nerves had been severed.
1875. Benjamins could not find the striation to be a constant
occurrence, and failed to find the processes described by Thanhoffer.
1876. Krause found rod-like bodies round the margin of the border.
1877. Fortunatow supported Thanhoffer’s view.
1881. Landois observed appearances in Spelerpes fuscus, which led him
to support Thanhoffer’s views.
1883. Wiedersheim supported Thanhoffer’s views.
1884. Wiemer supported Thanhoffer’s observations.
1888. Paneth failed to find any contractile protoplasmic processes,
and asserts that the circumference of the border, when examined under
certain conditions, is composed of rods.
From the same causes the goblet- or chalice-cells, already mentioned,
have been the subject of much speculation and investigation.
1846. Frerichs drew and described these cells as empty cells.
In 1848 these cells were first described as epithelium capitatum by
Gruby and Delafond.
In 1856 Donders described the cells as being open, and as discharging
their contents into the canal; the cell-walls being then pressed
together by the neighbouring cells, and the cell-contents being then
gradually reformed.
In the same year Kölliker published results closely agreeing with
those of Donders, and he traced the various stages of the process.
1857. Brettauer and Steinach held them to be cells which had lost
their contents, and as the ‘cuticular border’ was absent, concluded
that the cell-contents were in closer connection with the ‘border’
than with the rest of the cell-wall.
1865. Lipsky and Sachs both doubted the presence of such cells, and
considered them due to the action of reagents or post-mortem change.
1866. Letzerich described the cells as open, and regarded them as the
commencement of the lacteal system, while Dönitz thought the whole
appearance due to reagents.
1867. Schultze and Eimer, independently, described them as
unicellular glands. Erdmann, however, again denied their occurrence
under normal conditions.
Oeffinger held the goblet-cells to be modified ordinary cylindrical
epithelium cells; in which view he was supported by Arnstein.
1868. Schultze and Eimer, after renewed investigations, reiterated
their former opinions.
1869. Eimer described the goblet-cells as secreting mucin, and as
capable, by division, of throwing out pus-like cells.
1876. Krause described the cells as containing granular contents,
which under certain conditions are thrown out.
1877. Tolldt considered them artificial productions. Edinger asserted
that they are formed from the cylindrical cells.
1877–1885. Partsch (1877), Klein and Hebold (1879), Stöhr (1880),
Patzelt (1882), Haller (1883), Holl (1885), support the last view.
1878. Hoffmann supported Schultze’s views.
1886. List describes these organs as unicellular mucous glands.
1887. Paneth described them as secreting mucous and as being derived
from the cylindrical cells.]
(5) [The *blood-vessels* of the small intestine (p. 234) have been
described by Langer; he finds the vessels arranged in networks, one
a subserous network, placed underneath the serous coat, and formed
of elongated, irregular, four-cornered meshes. When the intestine is
distended the meshes are rectangular.
The vessels to the mucous membrane divide and anastomose very freely
in the submucous layer, and then form an irregular network on the
inner surface of the _Muscularis mucosa_; this network follows all the
foldings of the mucous membrane, and thereby supplies a double layer
to each villous fold of the mucous membrane. The meshes are usually
four-sided or five-sided.]
(6) [The *lymphatics* of the small intestine (Figs. 190, 191). The
lymphatic vessels on reaching the intestine usually bifurcate; the two
branches, as a rule, follow and enclose an arterial twig. From the
serous layer they receive the contents of a very fine lymphatic plexus,
the lumens of which are slightly greater than that of the corresponding
capillaries; from the mucous layer they receive the contents of the
lacteals: between these two layers the lymphatics anastomose very
freely by means of numerous branches (Langer).
The lacteals are lined with an epithelioid layer and traversed by
connective-tissue trabeculae, which have a like covering. The lacteals
are not simple but in the form of a coarse network (Fig. 189) (Langer).]
[Illustration: Fig. 190.
Isolated fold of mucous membrane of small intestine of _Rana
temporaria_; after Langer. Forty times natural size. Blood-vessels
striped, lacteals shaded. ]
(7) [The *nerves* of the small intestine (p. 200) usually follow the
arteries to the muscular coats, between which they form a plexus
(Auerbach’s plexus); from this numerous twigs are given off, which
course alone or in company with vessels to the mucous coat, where
a second plexus (Meissner’s plexus) is formed. Auerbach’s plexus,
according to Klein, consists of bands of nervous fibrils in endothelial
sheaths; they branch and inosculate, and thus form a plexus. Where
several such branches meet, a more or less complicated decussation of
the bands of fibres takes place. Along these nervous bands are ganglion
cells, either isolated or in groups. The cells are large, generally
spherical, and contain a sharply outlined nucleus with a single or
double nucleolus. The smaller cells generally appear to possess only
one process, which can be traced from the protoplasm of the cell
between the fibrils of the nerve-trunk. The larger cells are distinctly
multipolar, their protoplasm being provided with a number of fine
processes, or, as is oftener the case, with one large and several small
processes. In many instances Klein was able to distinguish around the
ganglion-cells a capsule of a spherical or ovoid shape. In these cases
the body, as well as the processes of the ganglion-cell, were lying
within the capsule. This system of ganglion-cells is in connection with
the individual bundles within the nerve-trunks.
[Illustration: Fig. 191.
Transverse section of a fold of the mucous membrane of _Rana
temporaria_; after Langer. Sixty times natural size.
_A_ Lacteals with transverse trabeculae.
_B_ Circular muscular layer.
_C_ Longitudinal muscular layer.
Blood-vessels striped.
]
Klein describes a second system of ganglion-cells, situated in meshes,
which are formed by the nerve-trunks of the plexus itself. These
ganglion-cells are much larger than the former, and are multipolar;
their protoplasm, which is distinctly fibrillar, with granules between
the fibrils, is provided with one or two long, thick processes and
several short and thin ones; generally the processes are branched. The
general shape of the cells is oblong, the thick, long processes being
commonly at the two opposite poles. The cells are generally isolated,
sometimes situated in the centre of a mesh, or more commonly near a
nerve-trunk that borders the mesh on one side. Each ganglion-cell is
connected with a nerve-trunk of the plexus by at least one process. In
a few of the nerve-trunks of the general plexus, isolated medullated
nerve-fibrils are seen to pursue an almost straight course from one
trunk into another and divide into two. There is no connection between
these medullated fibres and the ganglion-cells.
*Auerbach’s plexus* is a much finer plexus than that just described,
and the ganglia are much smaller. It supplies twigs to the _Muscularis
mucosa_; these break up into fine fibrils, which follow the direction
of the muscle-fibres; other twigs supply the blood-vessels, with which
they can be traced into the bases of the folds of mucous membrane.
Thanhoffer has recently (_l. c._) described nerve-fibrils, which
terminate in the mucous epithelium.]
D. The _Large Intestine_ (Fig. 184 _R_).
[Illustration: Fig. 192.
From a transverse section of the large intestine of _Rana temporaria_,
moderately distended.--G. H.
_A_ Denser portion of submucous coat.
_B_ Looser portion of submucous coat.
_C_ Artery, cut obliquely.
_D_ Circular muscle-layer.
_E_ Longitudinal muscle-layer.
]
*a.* *General description.* The large intestine is a flask-shaped
viscus, lying in the median line. The small intestine opens into it
by an abrupt curve at its anterior end. The large intestine is the
widest part of the alimentary canal, is thin-walled, and diminishes in
width towards its hinder end, where it opens into the cloaca above the
opening of the bladder.
*b.* [*Minute structure.*
(1) The *serous coat* resembles that of the small intestine, etc.
(2) The *muscular coats* resemble those of the small intestine, but are
thinner; the longitudinal layer is, however, proportionally thicker
(Wiedersheim).
(3) The *submucous coat* (Fig. 192) resembles that of the small
intestine in its general structure; the portion lying immediately
beneath the mucous membrane (_B_) is denser in structure.
This layer has no _Muscularis mucosa_.
(4) The *mucous coat* (_A_) is a simple layer of large, columnar,
epithelial cells, with large oval nuclei. The cells have a hyaline
free border, but this possesses no striation. The mucous membrane is
usually described as possessing numerous simple follicles (glands
of Lieberkühn); in those specimens which I have examined they have
been entirely absent (Figs. 192, 193). At six to eight points in a
transverse section of a rectum moderately distended the submucous coat
is thinner, and so throws the mucous coat into slight, longitudinal
grooves; but these do not in the least resemble the glands of
Lieberkühn.
[Illustration: Fig. 193.
Transverse section of large intestine of _Rana esculenta_; the mucous
membrane thrown into longitudinal folds in consequence of the organ
being contracted. Arteries injected with carmine.--G. H.
_A_ Large circular vessels within the muscular coats.
_B_ Fine anastomosis to the mucous coat.
]
(5) The epithelium possesses goblet- or chalice-cells (Hoffmann),
the number of which probably depends upon the period of the year and
the state of digestion. In the rectum, from which the section for
the figures 192 and 193 were cut, not one goblet-cell was found in a
complete series of sections.
If the rectum be contracted, the mucous membrane is thrown into
longitudinal folds.
(6) The *blood-vessels* (Fig. 193) have a simple arrangement. The
arteries are large, and form oblique loops around the intestine, lying
under the peritoneum; from these branches are given off to form a
series of rings in the submucous membrane (Fig. 193 _A_); from these
fine twigs are given off to form a fine anastomosis under the mucous
membrane (_B_).
(7) The *lymphatics* of the large intestine are arranged in two chief
systems: one under the serous coat resembles the corresponding system
of the small intestine. The second set forms a network of rounded loops
in the submucous coat, which give rise to a secondary set of smaller
vessels towards the mucous membrane; this secondary system forms a sort
of trellis-work standing on the rounded loops, and so maps out small
blocks of the thick submucous coat. Towards the cloaca the arrangement
is simpler; the secondary lymphatics are lost, while the primary
lymphatics tend to form elongated, longitudinal loops (Langer).]
II. THE GLANDS CONNECTED WITH THE INTESTINAL CANAL.
A. The *Liver* and *Gall-bladder*.
*a.* *External form.*
(1) The liver (Figs. 185, 194) is a large, reddish-brown organ,
occupying a large part of the anterior abdominal region. It consists
of three or more lobes, which present many individual variations; as a
rule there are two larger lateral lobes (_L_ and _L^1_), and a smaller
median lobe (_L^2_). Each lobe has a superficial or ventral surface,
which is convex, and a deep or dorsal surface, which is concave and
directed towards the other abdominal viscera lying above the liver. The
two surfaces of each lobe meet to form a sharp border around the lobe,
except where the three lobes are more intimately attached, opposite the
apex of the heart (Figs. 185, 194); at this place each lobe possesses a
small, flat, or slightly concave anterior surface.
The left lobe (_L_) hides the greater portion of the stomach, and has
near its inner border a deep fissure, which runs forwards and so marks
off a more or less well-marked fourth lobe. The anterior portion of the
left lobe is attached to the corresponding portion of the right lobe by
a narrow commissure.
[Illustration: Fig. 194.
The liver, seen from the ventral surface.
_Du_ Duodenum.
_H_ Heart.
_L_ Left lobe of liver.
_L^1_ Right lobe of liver.
_L^2_ Middle lobe of liver.
_M_ Stomach.
]
The median lobe (_L^2_) extends backwards as far as the pylorus, and
covers the commencement of the intestine together with the pancreas;
these organs can, therefore, not be seen until this lobe is displaced.
A fifth lobe is sometimes found on the dorsal surface of the median
lobe, and to it or to the dorsal surface of the median lobe the small
intestine is attached by the _Ligamentum hepato-duodenale_ (Fig. 195
_Lhp_). The _Vena portarum_ enters the liver behind this ligament.
The right lobe extends much further dorsalwards than the left lobe, and
even comes in contact with the lung, the vessels of which sometimes
indent its surface in spirit specimens. This lobe is also in contact
with the base of the fat-body, and in females with the oviduct.
By drawing the lobes of the liver to either side and displacing the
heart towards the head, the posterior caval vein is seen passing from
the liver to the heart, and the hepatic commissure joining the lateral
lobes is brought into view.
(2) The *gall-bladder* (Fig. 195 _G_) is placed on the dorsal surface
of the liver in the deep niche between the right and left lobes; it is
attached to the liver by connective-tissue and peritoneum.
The gall-bladder is round or oval in form; when moderately full it has
a smooth, outer wall, which is thin and allows the green colour of the
bile to be seen. It possesses a duct (_Dcy_), the cystic duct (_Ductus
cysticus_), which bifurcates near its origin.
The two cystic ducts (Fig. 195 _Dcy_) join the larger hepatic ducts,
as shown in the figure, and so form a simple anastomosis, from which
three branches (3) of varying size unite at the anterior extremity of
the pancreas to form the common bile-duct (_Ductus choledochus_, _Dc_).
The common bile-duct runs through the whole length of the pancreas,
receiving near its origin additional hepatic ducts (_Dh^1_) from the
middle lobe of the liver. In this course the duct lies either on the
ventral surface of the pancreas or under a thin layer of the glandular
tissue; it receives the ducts of the pancreas and leaves that organ
at its posterior border as a round and strong canal (_Dc^1_). The
duct courses in the gastro-duodenal ligament, and reaches the dorsal
surface of the duodenum at a very acute angle; it then pierces the wall
obliquely and terminates with a slit-like or elongated oval opening.
[Illustration: Fig. 195.
The pancreas and bile-canals. The liver has been displaced towards the
head.
_Dc_ Common bile-duct.
_Dc^1_ Common bile-duct after leaving the pancreas.
_Dc^2_ Opening of the common bile-duct into the duodenum.
_Dcy_ Cystic ducts.
_Dh_ Hepatic ducts.
_Dh^1_ Supplementary hepatic ducts from the middle lobe
of the liver.
_Du_ Duodenum.
_G_ Gall-bladder.
_L_ Left lobe of the liver.
_L^1_ Right lobe of the liver.
_L^2_ Middle lobe of the liver.
_L^3_ Fourth lobe of the liver.
_Lhp_ Gastro-hepatic ligament.
_M_ Stomach.
_P_ Pancreas.
_Py_ Pylorus.
_P^1_ Ducts of the pancreas.
]
*b.* [*Minute structure.*
(1) The *liver* is composed of various tissues: it possesses a
peritoneal covering, a fibrous covering, which supplies trabeculae to
support the various other tissues, blood-vessels, hepatic cells or true
liver parenchyma, and bile-canals.
α. The *peritoneal covering* of the liver encloses the organ almost
completely, the only exceptions being where the various attachments
of the liver are found (see peritoneum). The peritoneal covering of
the liver is for the most part composed of flattened, ciliated cells
(Neumann and Grunau); on the middle lobe these are, however, more or
less replaced by non-ciliated cells. The thickness of these cells
varies considerably, according to the amount of distension to which the
liver is subjected.
β. The *fibrous covering* of the liver is very thin and very difficult
to demonstrate; it consists of connective-tissue fibres with very few
corpuscles. This covering is prolonged into the liver along the portal
canals, where traces of connective-tissue can always be made out.
From these processes and from the whole of the inner surface of the
general connective-tissue capsule are given off fine trabeculae, in
which it is very difficult to find any nuclei; these trabeculae are
everywhere extremely delicate and difficult to demonstrate; nowhere do
they form distinct boundaries between lobuli: the structure closely
resembles the sustentacular tissue of a lymphatic gland (Eberth).
γ. The *blood-vessels* to the liver are the portal vessels (p. 249) the
hepatic veins (p. 247), and the hepatic artery[74] (p. 233)
[Footnote 74: See Plate II, Fig. 196.
I. Partial injection of the liver from the portal vein (blue): _Rana
esculenta_.--G. H.
II. Partial injection of the liver from the hepatic vein (red): _Rana
esculenta_.--G. H.
III. Complete injection of the liver from the hepatic artery (red) and
from the portal vein (blue): _Rana esculenta_.--G. H.
_A_ Portal (interlobular) veins and their branches.
_B_ Hepatic (intralobular) veins and their branches.
_C_ Hepatic arteries and their branches.
]
(1) The portal vessels pass into the liver on its ventral surface; they
divide into branches which course along the middle parts of each lobe
and give off smaller branches in all directions towards the periphery;
the interlobular branches (Fig. 196 I) forming a very complex capillary
network. As compared with the hepatic veins (Fig. 196 II), the
interlobular veins do not give off their capillaries so abruptly, but
tend to supply these from small lateral branches. The portal veins are
accompanied in their course by branches of the hepatic artery, and
often by larger bile-ducts, and thus form portal canals. In no part do
the portal (interlobular) veins or their branches limit the lobules
by distinct rings of vessels, as seen in many higher animals. The
interlobular veins and intralobular veins simply interdigitate with
each other.
(2) The hepatic veins (Fig. 196 I and II) also course chiefly in the
middle parts of the lobes of the liver; they branch, and ultimately
supply intralobular veins which interdigitate with the interlobular
veins (I and II). The capillaries arise very abruptly from an
intralobular vein, and form a network of vessels communicating very
freely with the corresponding capillaries of the interlobular veins.
(3) The hepatic arteries (Fig. 196 III) break up into small branches
which, as a rule, course along the portal canal until near the surface
of the liver, when they leave the portal veins and pass to the surface
to supply the coverings of the liver. In their course along the portal
canals they supply a few very small twigs to the structures forming the
canals. At the surface of the liver the branches of the hepatic artery
form capillaries, which empty themselves into the general capillary
anastomosis beneath (Fig. 196 III).
δ. The *liver-cells* (Figs. 197, 198) are large, and of compressed
spheroidal or polygonal shape. They possess no cell-wall, have usually
one but sometimes two large nuclei, each with a distinct nucleolus.
The cells often contain granules of glycogen or fat-globules. The main
fibrillae of the intercellular network are arranged so as to extend
between a bile-capillary and a blood-capillary (Fig. 197).
ε. The *bile-ducts* (Fig. 198) commence as fine tubes between the
liver-cells, where they are simply small spaces enclosed by the hepatic
cells; they are usually enclosed by three or four cells, possibly
sometimes by only two cells (Hering). Such bile-capillaries are usually
separated from a blood-capillary by the thickness of one liver-cell
only (Fig. 198).
As a number of such bile-capillaries run together to form a larger
duct, the cells enclosing them change their character, becoming
flattened and broader; these cells may, however, be traced continuously
into the true hepatic cells (Hering and Eberth). The bile-duct so
formed then obtains a slight covering of fibrous tissue, which rapidly
increases in quantity, courses along a portal canal, and receives other
ducts on the way; the epithelium lining it gradually becomes more
elongated, and ultimately resembles that found in the common bile-duct
or the gall-bladder.
In the larger ducts the epithelium is, according to v. Brunn,
ciliated; they also possess a layer of unstriated muscle-fibre
(Eberth).]
[Illustration: Fig. 197
Liver-cells, after Kupffer.]
ζ. The *pigment* of the liver varies very much in amount and character,
according to the time of the year and state of health of the animal.
According to Eberth the pigmentary masses are of about the same size as
the white blood-corpuscles, and are possessed of the power of amoeboid
movement (in young animals). The cells possess two to seven nuclei and
vary much in colour and distribution. As a rule the larger the amount
of pigment in a given liver the smaller is the number of fat-globules
found in the individual liver-cells (Eberth).]
[Illustration: Fig. 198.
The bile-capillaries; natural injection with sulphindigotate of sodium:
v v v represent blood-capillaries.--G. H.]
(2) [The *gall-bladder* and *bile-ducts*. The gall-bladder has four
coverings.
α. A serous coat of peritoneal endothelium.
β. A muscular coat, containing unstriated muscle-fibres and
connective-tissue.
γ. A sub-mucous coat of areolar-tissue.
δ. An internal lining of columnar epithelium.
ε. The walls of the gall-bladder are richly supplied with blood-vessels
from the cystic arteries (p. 233); these form a close network in the
submucous coat.
ζ. The muscular and submucous coats also possess a rich nervous plexus,
which contains ganglia and resembles Auerbach’s plexus of the intestine
(Popoff, Gerlach).]
B. The *Pancreas* (Fig. 199 _P_).
*a.* *General description.* The pancreas is a flattened, light
yellowish-brown organ, placed in the loop of the duodenum between this
latter and the stomach. The whole organ is within the gastro-duodenal
ligament, and is attached to the liver; hence it is little influenced
by changes in the amount of distension of the stomach or intestine.
[Illustration: Fig. 199.
The pancreas and bile-canals. The liver has been displaced towards the
head.
_Dc_ Common bile-duct.
_Dc^1_ Common bile-duct after leaving the pancreas.
_Dc^2_ Opening of the common bile-duct into the duodenum.
_Dcy_ Cystic ducts.
_Dh_ Hepatic ducts.
_Dh^1_ Supplementary hepatic ducts from
the middle lobe of the liver.
_Du_ Duodenum.
_G_ Gall-bladder.
_L_ Left lobe of the liver.
_L^1_ Right lobe of the liver.
_L^2_ Middle lobe of the liver.
_L^3_ Fourth lobe of the liver.
_Lhp_ Gastro-hepatic ligament.
_M_ Stomach.
_P_ Pancreas.
_P^1_ Ducts of the pancreas.
_Py_ Pylorus.
]
The organ may be completely exposed by either of two methods: in
the former, the liver, stomach, and duodenum are drawn towards the
head and the dorsal surface of the organ so exposed. In the second
method the liver is drawn backwards, the various peritoneal folds
which connect the duodenum with the posterior border of the liver cut
through, and the three organs then separated; the pancreas can then be
conveniently examined.
The size and shape of the pancreas are subject to great variations
in different specimens. The usual shape of the organ is somewhat
triangular (Fig. 199), the left border being usually unbroken, while
the other two shorter borders are broken into lobes. The longest lobe
stretches as far as the pylorus (_Py_), to which it is attached by
connective-tissue: the opposite extremity of the gland is attached to
the liver.
The excretory duct of the pancreas (_Ductus Wirsurgianus_) opens into
the common bile-duct at about the middle of the pancreas (_P^1_); other
smaller ducts may open into the same canal.
*b.* *Minute structure.* [The pancreas consists of a number of lobes
loosely held together by connective-tissue; each lobe is composed of
a number of lobules attached to each other much more intimately. The
lobules are made up of tubes lined by a single layer of glandular
epithelium. This epithelium is, as a rule, broadly columnar, but in the
smaller tubes may be cubical or polygonal. Each cell has a cell-wall,
nucleus, and very granular protoplasm; the latter shows two zones (in
the inactive condition), a granular zone near the lumen, and an outer,
clear, and finely striated zone (Nussbaum). The lumen of each alveolus
is very small, and in many cases difficult to make out.
The smallest ducts have no special lining, and are therefore bounded
by the glandular cells; the larger ducts have a flattened, cubical
epithelium, which when seen from the surface has an appearance as if
the individual cells were widely separated from one another; these
ducts have a considerable layer of connective-tissue around them. The
largest ducts are lined with a layer of columnar, ciliated epithelium;
the cilia are very long, usually of about the same length as the cell,
sometimes appearing to be even longer. This epithelium is continuous
with the ciliated, epithelial layer of the common bile-duct, which
it resembles. These largest ducts have an extremely thick layer of
connective-tissue around them.
The pancreas and its ducts are very richly supplied with vessels
and nerves; the nerves forming everywhere a fine plexus, the larger
strands of which usually, but not always, course with the larger
blood-vessels. The larger ducts have an especially rich supply of
nerves, of which fibrils may be traced towards the ciliated epithelium;
an anatomical connection between the two has not, however, been made
out.]
III. THE SPLEEN.
*a.* *General description.* Although the spleen belongs to the
lymphatic system, it is considered here in order to complete the
description of the abdominal viscera. It is a small, rounded-oval body,
of a reddish-brown colour, suspended in the mesentery near the anterior
end of the large intestine (Fig. 184 _Mz_). In medium-sized animals
the longer diameter is about 6 mm., and is parallel with the long axis
of the body; the shorter diameter is about 5 mm., and the thickness
varies from about 3 mm. to 4 mm. The dorsal surface is flat or slightly
concave (_Hilus lienis_), and receives the relatively large afferent
and efferent vessels; the rest of the organ is smooth and rounded, and
with its greatest convexity directed towards the left side.
*b.* [*Minute structure.* The structure of the spleen resembles that of
higher animals. It possesses a *serous coat* of peritoneum, under which
is a *fibrous coat*; the latter sends in trabeculae, which divide and
form a fine meshwork of supporting-tissue; the finest trabeculae are
formed by the processes of the connective-cells of the sustentacular
structure. According to Hoffmann, the thickness of the fibres averages
0.001 to 0.011 mm.; the intervening spaces measure 0.002 to 0.012 mm.
The spaces are filled by the spleen pulp, which consists of true
spleen-corpuscles, blood-corpuscles, and pigment-corpuscles.
The *spleen-corpuscles* have an average diameter of 0.006 mm., and are
round or of a rounded oval form. Each consists of a nucleus, with a
very small amount of adherent protoplasm; the nucleus possesses one or
two nucleoli. Some of these cells contain a brownish or black pigment
in granules, but most of them are colourless (Hoffmann).
The *pigment-cells* equal the white blood-corpuscles in size, and
exactly resemble the corresponding pigment-cells of the liver.
The *blood-corpuscles* are found in various stages of disintegration
and regeneration.
The *arteries*, on entering the spleen, at once break up into branches
which pass in all directions, giving off twigs on all sides and at
varying angles; from these capillaries are supplied, which traverse the
parenchyma in all directions. The capillaries empty themselves partly
into veins, partly into the splenic spaces.
The *veins* commence either as capillaries in connection with
the arteries or by communicating with the splenic spaces. This
communication is brought about by small twigs of about 0.015 mm.
diameter, which have incomplete walls, and so open into the splenic
spaces (Hoffmann).
*Malpighian bodies* are represented by collections of splenic cells on
various arterial twigs; they are, however, not so sharply defined as is
the case in some higher animals.]
IV. THE PERITONEUM.
*a.* *General description.* The *peritoneum* is a thin, pigmented
membrane lining the abdominal cavity. Tracing it forwards from the
ventral wall of the abdomen (_Peritoneum parietale_), it can be
followed along the deeper surface of the muscles to the pericardium.
The middle portion leaves the abdominal wall by accompanying the
anterior abdominal vein; the lateral portions are continued further
forwards, and then ascend on the pericardium and the deeper surfaces of
the lateral walls in the thoracic region.
The peritoneum passes thence to the ventral surface of the liver
(_Ligamentum coronarium_), covers this surface and passes on to the
dorsal surface of the organ, which, together with the gall-bladder,
it completely encloses. The membrane thus reaches the dorsal wall
(_Ligamentum suspensorium hepatis et pericardii_); from the lateral
borders of the liver it passes upwards to the dorsal wall, and thus
forms a pocket-like pleuro-peritoneal cavity on either side.
From the dorsal wall and above the attachment of the coronary ligament
of the bladder the peritoneum reaches the root of the lung on each
side, and completely invests the organ: while in the middle line it
covers the outer surface of the oesophagus and attaches it to the
dorsal wall, thus forming the first part of the mesentery.
Just behind the root of the lung, the peritoneum, in female specimens,
has an opening on each side (_Ostium abdominale tubae Fallopiae_), by
which the oviduct communicates with the peritoneal cavity.
Tracing the peritoneum backwards, it passes over the ventral surface
of the kidneys so as to exclude them from the peritoneal sac: in the
middle line, between the kidneys, the peritoneum descends to form the
mesentery for the small intestine. At the inner borders of the kidneys,
the testes or ovaries are pushed into the abdominal sac, and so possess
well-marked mesenteries; the mesovarium becomes longer towards the
cloaca, but attains its greatest development in the breeding season,
when it is arranged in numerous folds. Along the outer borders of the
kidneys, in females, the peritoneum again descends into the abdominal
cavities to enclose the oviducts, which have broad mesenteries. Towards
the rectum these mesenteries are shorter and attached to either side
of the bladder by a well-marked free border: as the middle line of
the bladder is attached by the peritoneum to the rectum, two distinct
pouches (_Cava recto-vesicalia_) are formed, which descend deeply
into the pelvic cavity. The upper walls of these pouches are pushed
in between the urostyle and the rectum, and together form a strong
meso-rectum, which is longer near the _Valvula Bauhinii_ and continuous
with the mesentery of the small intestine. The hinder portion of this
mesentery is very short, and only covers the lateral walls of the
rectum.
With the exception of a small portion of its dorsal surface, which is
attached to the rectum, the whole surface of the bladder is covered
with peritoneum.
The mesentery of the alimentary canal commences in connection with
the oesophagus between the roots of the lungs; it is attached to the
dorsal surface of the liver, covering the posterior caval vein, and is
attached to the gall-bladder. From this point it extends, as a free,
arched fold, to the concave right border of the stomach, which is
completely surrounded by peritoneum.
The gastro-duodenal fold (_Ligamentum gastro-duodenale_) extends
from the stomach to the pylorus and includes the pancreas. The
hepato-duodenal fold (_Lig. hepato-duodenale_) extends from the portal
fissure of the liver to the duodenum.
The mesentery of the small intestine is broad and arranged in folds,
which follow the curves of the intestine; and is attached in the middle
line, immediately beneath the vertebrae, where it encloses the aorta.
The various folds and mesenteries carry the blood-vessels and nerves
to the different organs; in this course the vessels are surrounded by
large lymphatics, which communicate with each other.
[Illustration: Fig. 201.
Preparations from the peritoneum of _Rana esculenta_.--G. H.
I. From peritoneum of the ventral wall of abdomen, stained with silver
and logwood (Hartnack, Oc. I, Syst. 7).
II. From mesentery of small intestine of _Rana esculenta_, stained with
silver (Hartnack, Oc. I, Syst. 7).
III. Preparation to show ciliated cells between non-ciliated cells;
after Neumann. IV. Vertical section at border of liver to show ciliated
epithelium; after Neumann.
_A_ Stoma.
_B_ Pigment-cells.
_C_ Ciliated cells.
_D_ Non-ciliated cells.
]
*b.* *Minute structure* (Fig. 201).
[The peritoneum is a serous membrane, formed for the most part of a
layer of irregular endothelial cells, arranged on a thin layer of
subserous, connective-tissue (Fig. 201 I, II, and III).
The endothelial cells are attached to each other by cement-substance,
easily stained by silver nitrate. The cells covering the general
surface of the peritoneal cavity are larger and broader than those
covering the mesentery of the small intestine (compare I and II,
Fig. 201).
At various points stomata are found, bordered by smaller and more
deeply staining epithelium (I, _A_). The membrane covering the general
cavity is also much more pigmented than that covering the mesentery
(compare I and II).
Various portions of the peritoneal surface possess ciliated cells,
and these cells are usually thicker than the surrounding non-ciliated
cells. Such cells are found especially near the openings of the
oviducts and on the liver. The dimensions of the cells vary; according
to Neumann the average dimensions of ciliated cells on the liver
are: 0.006 mm. depth (without the cilia); nucleus, 0.012 mm. long
and 0.003 mm. broad. The cells are five- or six-sided and bounded by
straight sides (Neumann).]
SECTION VI.
THE LARYNX, LUNGS, VOCAL SACS, THYMUS AND THYROID GLANDS, AND THE
LYMPHATIC GLANDS (TONSILS?) OF THE HYOID REGION.
THE LARYNX, LUNGS, VOCAL SACS, ETC.
LITERATURE.
THE LUNGS AND LARYNX.
*Arnold, J.*, Zur Histologie der Lungen des Frosches. Virchow’s Arch.
1863. Vol. XXVIII, p. 433.
*Auerbach, L.*, Ueber den Bau der Blutcapillaren in den Lungen des
Frosches und an einigen andern Orten. Amtlicher Bericht über die
vierzigste Versammlung deutscher Naturforscher und Aerzte. 1886,
p. 241.
*Brittan*, Brit. and Foreign Medico-chirurgical Review, 1857. Vol. XX.
*Eberth, C. J.*, Ueber den feineren Bau der Lunge. Zeitschr. f. wiss.
Zool. 1863. Vol. XII, p. 427.
*Eberth, C. J.*, Ueber den Bau und die Entwicklung der
Blutcapillaren. Würzburger naturw. Zeit. 1866–67. Vol. VI,
pp. 27–32.
*Egorow, W.*, Ueber die Nerven der Lungen. Centralbl. f. med. Wiss.
1879, p. 305.
*Elenz, E.*, Ueber das Lungenepithel. Würzburger naturw. Zeit. 1864.
Vol. V, pp. 66–84.
*Frommann, C.*, Ueber die spontan, wie durch Durchleiten inducirter
Ströme, an den Blutzellen v. Salamandra maculata und an den
Flimmerzellen von der Rachen-schleimhaut des Frosches eintretenden
Veränderungen. Jenaische Sitzungsb. 1880.
*Gegenbaur, C.*, Ueber Drüsenzellen in der Lungen-Schleimhaut bei
Amphibien. Arch. f. Anat. u. Physiol. 1863, p. 157.
*Griffini, L.*, Contribuzione alla patol. del tessuto epiteliale
cilindrico. Arch. per le scienze mediche, 1884. Vol. VIII,
pp. 1–43.
*Grützner*, Physiologie der Stimme und Sprache. Hermann’s Handb. d.
Physiol. Vol. I, Pt. II, p. 146.
*Henle, J.*, Vergleichende Anatomische Beschreibung des Kehlkopfes.
Leipzig, 1839.
*Hoffmann, C. K.*, in Bronn’s Klassen und Ordnungen des Thierreichs.
Leipzig und Heidelberg, 1873–78. Vol. VI, pp. 514–531.
*Hoffmann, T.*, Die Lungengefasse der Rana temporaria. Dissert.
Dorpat, 1875.
*Holmgren, F.*, Upsala Läkareförenings Förhandlingar, 1867. Vol. III,
pp. 389–399.
*Howes, G. B.*, On a hitherto unrecognised feature in the larynx of
the anurous amphibia. Proc. Zool. Soc. London, 1887, p. 491.
*Hüter, C.*, Ueber den Kreislauf und die Kreislaufsstörungen in der
Froschlunge. Centralbl. f. med. Wiss. 1873. Nos. 5 and 6.
*Kandarazki, M.*, Ueber die Nerven der Respirationswege. Arch. f.
Anat. u. Phys. 1881, p. 1.
*Küttner*, Beitrag zu den Kreislaufsverhältnissen in der Froschlunge.
Virchow’s Arch. 1874. Vol. LXI, p. 21.
*Leydig*, Anatomische-histologische Untersuchungen über Fische und
Reptilien. 1853.
*Malpighi*, De pulmonibus. Oper. omn. Lugd. Batav. 1687. Vol. II,
p. 328.
*Müller, H.*, Ueber das Vorkommen glatter Muskelfasern in den Lungen
der Amphibien. Würzburger naturw. Zeit. 1861.
*Pertik, O.*, Untersuchungen über Nervenfasern. Arch. f. mik. Anat.
1881. Vol. XIX, p. 183.
*Ranvier, L.*, Leçons sur l’histologie du système nerveux. Vol. I,
pp. 98–101.
*Schestopol, A.*, Ueber die Durchlässigkeit der Froschlunge für
gelöste und körnige Farbstoffe. Virchow’s Arch. 1879. Vol. LXXV,
p. 199.
*Schultze, F. E.*, Epithel und Drüsenzellen. Arch. f. mik. Anat.
1867. Vol. III, p. 145.
*Schultze, F. E.*, Die Lungen, in Stricker’s Handbuch der Gewebelehre.
*Stirling, W.*, On the nerves of the lungs of the newt. Journ. of
Anat. and Physiol. 1882, p. 96.
*Treviranus, C. R.*, Beobachtungen aus der Zootomie u. Physiologie;
nach dessen Tode herausgegeben von L. C. Treviranus. Bremen, 1839.
THE THYMUS GLAND.
*Ecker*, Blutgefässdrüsen, in Wagner’s Handwörterbuch der
Physiologie, 1853. Vol. IV, p. 114.
*Fleisch, E.*, Ueber den Bau einiger sogenannten Drüsen ohne
Ausführungsgänge. Wiener Akad. Sitzungsb. 1870. Vol. LX, Pt. II,
p. 55.
*Gegenbaur*, Vergleichende Anatomie.
*Hoffmann, C. K.*, Bronn’s Klassen und Ordnungen des Thierreiches.
1873–1878. Vol. VI, p. 503.
*Leydig*, Lehrbuch der Histologie. 1857, p. 422.
*Tolldt*, Ueber lymphoide Organe der Amphibien. Wiener Acad.
Sitzungsb. 1868. Vol. LVIII, Pt. II, p. 171.
*Watney, H.*, The minute anatomy of the thymus. Phil. Trans. 1882.
Vol. CLXXIII, p. 1100.
THE THYROID GLAND.
*Baber, E. C.*, Researches on the minute anatomy of the thyroid
gland. Phil. Trans. 1881. Pt. III, p. 577.
*Ecker*, Blutgefässdrüsen, in Wagner’s Handwörterbuch der
Physiologie, 1853. Vol. IV.
*Fleisch, E.*, Ueber den Bau der sogenannten Schilddrüse des
Frosches. Wiener Acad. Sitzungsb. 1868. Vol. LVIII, p. 57.
*Hoffmann, C. K.*, Bronn’s Klassen und Ordnungen des Thierreiches.
1873–1878. Vol. VI, p. 503.
*Huxley* and *Martin*, Practical Biology. 4th edit., 1877, p. 181.
*Leydig*, Lehrbuch der Histologie. 1857, p. 376.
*Müller, J.*, Ueber die Entwicklung der Schilddrüsen des Frosches.
Wiener Sitzungsb. 1871. Vol. VI, pp. 428–553.
*Müller, W.*, Ueber die Entwicklung der Schilddrüse. Jenaische
Zeitschr. 1871. Vol. VI, p. 438.
*Poincaré*, Zur Anatomie der Glandula thyroidea. Journ. de l’anat. et
de la physiol. 1877. Vol. XIII, pp. 123–143.
*Rolleston*, Forms of Animal Life. 2nd Edit. 1888, p. 77.
*Zeiss, O.*, Mikroskopische Untersuchungen über den Bau der
Schilddrüse. Dissert. Strassburg, 1877.
THE LARYNX, LUNGS, VOCAL SACS, ETC.
I. THE LARYNX.
The larynx (Fig. 202) is a short wide tube placed between the posterior
cornua of the hyoid, to which it is attached by connective-tissue. The
long axis of the tube lies in the median line and almost horizontally,
but the posterior end is on a slightly lower level than the anterior,
when the animal is in the natural sitting position (Fig. 202). The
anterior end of the larynx opens into the mouth by a longitudinal slit
(Fig. 179 _L_), and is placed in a slight depression caused by the
folding of the mucous membrane; the posterior end communicates with the
cavities of the lungs.
[Illustration: Fig. 202.
Dissection to show the position and relations of the larynx. The animal
(_Rana esculenta_) is in the natural sitting position; the toes of the
fore-foot are, however, too much flexed.--G. H.
_B_ Brain.
_C_ Gall-bladder.
_E_ Opening of Eustachian tube.
_Eo_ Oesophagus.
_F_ False vocal cords.
_G_ Epiglottis.
_H_ Heart.
_L_ Liver.
_V_ True vocal cords.
]
The larynx is lined with mucous membrane, which is continuous, in front
with that of the mouth, behind with that of the lungs. The organ has
a skeleton of cartilage, and possesses special muscles, by which the
supply of air to the lungs, and the voice can be regulated.
*a.* The *cartilages* of the *larynx*.
The cartilages of the larynx are five in number, of which four are
paired and one is single.
(I) The *cricoid cartilage* (Figs. 203, 204) is an oval ring of
cartilage with various processes. The ring-like portion of the
cartilage is placed in a plane which is almost vertical, but which
is directed slightly upwards anteriorly, and slightly downwards
posteriorly (the animal being in the usual sitting position).
[Illustration: Fig. 203.
The cartilaginous skeleton of the larynx.
I. Seen from in front; the spinous process would normally be more
curved.
II. Seen from the left side; the spinous process should be more curved.
_Ca_ Right arytenoid cartilage.
_Ca^1_ Left arytenoid cartilage.
_C.l.^1_-_C.l.^4_ Cricoid cartilage.
_P_ Lateral plate of cricoid cartilage.
_Sp_ Spine of cricoid cartilage.
_SR_ Opening to larynx.
*** The two outer asterisks are above the two apices
of the left arytenoid cartilage; the middle one
above the pre-arytenoid cartilage.
]
The sides of the ring are slightly curved inwards on the anterior
surface, and possessed of irregular enlargements (_C.l.^1_-_C.l.^4_),
the space enclosed by this portion of the cartilage is occupied by a
membrane (_M_), which forms the floor of the body of the larynx.
From each side of the body of the cartilage, a process (_C.l.^2_)
is given off, which curves backwards and inwards to join its fellow
of the opposite side, the two forming a blunt spinous process
(_Sp_), which projects backwards, and is intimately attached to the
oesophagus. Between these processes and the lower portion of the body
of the cricoid cartilage are the apertures of the roots of the lungs
(Fig. 203), which, by their attachments to these cartilages, are kept
open.
(2) The *arytenoid cartilages* (Fig. 203 I, II, _Ca_, _Ca^1_) are a
pair of cartilages placed in front of the cricoid cartilage, one on
each side. Each cartilage is semilunar in shape, concave internally,
and convex externally. The cartilages are placed almost vertically,
with their posterior borders or bases parallel to the body of the
cricoid cartilage. The superior borders (Fig. 204) are directed upwards
and forwards, the inferior downwards and forwards. The superior and
inferior borders are separated by a semicircular notch, bounded
by two sharp apices. The superior and inferior angles of the two
cartilages are close together, and movably attached to each other by
connective-tissue.
These cartilages vary very greatly in the two sexes. In the males they
are thick, strong, and large; in the female the cartilages are very
thin, more hollowed and much smaller.
[Illustration: Fig. 204.
The larynx and surrounding parts, seen from the ventral surface.
_Ca^1_ Arytenoid cartilages.
_Cl^1_-_Cl^4_ Cricoid cartilage.
_G_, _G^1_ Fibrous tissue connecting the larynx
with the posterior cornua of the hyoid.
_H_ Lesser cornua of the hyoid.
_HH_ Greater cornua of the hyoid.
_Lg_ Right lung.
_Lg^1_ Left lung.
_M_ Fibrous membrane filling the ring-like
cricoid cartilage.
_Ph^4_ The M. petrohyoideus tertius.
_S_ Part of tendon of M. petrohyoideus tertius.
_SB_, _SB^1_ Mucous membrane bulging from the
anterior ventricle of the larynx.
_Sp_ Spinous process of the cricoid cartilage.
_ZK_ Body of the hyoid.
]
(3) [The *pre-arytenoid cartilages* (Fig. 206 I, _P_) are two small
elongated cartilages placed in the semicircular notch between the
superior and inferior borders of the arytenoid cartilages. They
are subject to much variation in size, sometimes being merely a
very slender rod, at others a moderately thick oval mass. In female
specimens they appear to be, at times, absent, or to unite with the
arytenoid cartilages, as in these cases a third very small apex is
found on each arytenoid cartilage; but it is always much smaller than
the two neighbouring apices.]
*b.* The *attachments* of the *cartilages* to each other.
The cartilages do not articulate directly with each other, but are
connected by connective-tissue only; there are, therefore, no synovial
sacs.
[Illustration: Fig. 205.
The muscles of the larynx.
_A.l._ Aperture between the arytenoid cartilages.
_C.l._ Cricoid cartilage.
_C.a.^1_ Superior angle of the arytenoid cartilage.
_C.a.l._ M. constrictor aditus laryngis.
_C.o.l._ M. hyo-arytenoideus anterior.
_C.o.l.^1_ M. hyo-arytenoideus posterior.
_D.l._ M. dilatator laryngis.
_G_ Connective-tissue.
_G^1_ Connective-tissue.
_H_ Smaller posterior cornua of the hyoid.
_HH_ Greater cornua of the hyoid.
_Jt_ Fibrous tissue into which the two
constrictions are inserted.
_Ph^2_ Second petrohyoid muscle (M. petrohyoid. I).
_Ph^3_ Third petrohyoid muscle (M. petrohyoid. II).
_Ph^4_ Fourth petrohyoid muscle (M. petrohyoid. III).
_S_, _S^1_, _S^2_ Tendon of the fourqth petrohyoid muscle.
_Sp_ Spinous process of the cricoid cartilage.
_ZK_ Body of the hyoid.
]
*c.* The *muscles* of the larynx[75].
[Footnote 75: The nomenclature adopted is that of Henle and Hoffmann.]
The muscles of the larynx appear in the following order, when dissected
from the mouth:--
(1) The _M. dilatator aditus laryngis_ (Henle), (Fig. 205 _D.l._)
arises on either side from the hinder end of the larger posterior
cornu of the hyoid: the fibres diverge slightly to be inserted into
the middle portion of the outer surface of the arytenoid cartilage; a
smaller bundle of fibres is attached to the deeper-lying constrictor
muscle and to the cricoid cartilage.
(2) The _M. constrictor aditus laryngis_ (Henle), (Fig. 205 _C.a.l._),
arises on either side from the hinder half of the dorsal surface of the
posterior cornu of the hyoid. The two muscles enclose the larynx, and
are inserted into a median tendinous raphe on the under surface of the
larynx (_Jt_). The raphe is connected with the skeleton of the larynx
by connective-tissue.
(3) The _M. hyo-arytenoideus anterior_ (Fig. 205 _C.o.l._) arises on
each side from the inner border of the anterior end of the cornu of the
hyoid; the muscle lies close to the anterior border of the arytenoid
cartilage, and is inserted into a fibrous lamella on the dorsal surface
of the larynx. The _M. petrohyoideus tertius_ is also partially
inserted into this lamella.
(4) The _M. petrohyoideus tertius_ (Fig. 205 _Ph^4_), (see also p. 66).
The greater part of this muscle is inserted into the end of the
posterior cornu of the hyoid (_HH_); a smaller portion (_S_, _S^2_)
is prolonged to be inserted into the cricoid cartilage and into the
fibrous lamella into which the _MM. hyo-arytenoidei anteriores_ are
inserted.
(5) The _M. hyo-arytenoideus posterior_ (Fig. 205 _C.o.l.^1_) arises
on each side from the superior angle of the corresponding arytenoid
cartilage, under cover of the tendon of the _M. petrohyoideus tertius_.
The muscle is inserted into the inferior angle of the arytenoid
cartilage.
*d.* The *interior* of the larynx (Figs. 202, 206, 207). The cavity of
the larynx is constricted at two points: anteriorly it is constricted
by the true vocal cords (Figs. 206 _V_, 207 _SB_), posteriorly by the
false vocal cords. The whole cavity is lined with mucous membrane,
which is continuous with that of the mouth anteriorly, with that of the
lungs posteriorly.
(1) The *true vocal cords* are two vertical flat bands of
connective-tissue, attached above to the superior angles of the
arytenoid cartilages, below to their inferior angles; their anterior
borders are thin and free; near their posterior borders they are
attached by mucous membrane to the internal surfaces of the arytenoid
cartilages. The anterior and posterior borders are not parallel but
are each concave (Fig. 202 _V_).
[Illustration: Fig. 206.
Three sections through the larynx of _Rana esculenta_.--G. H.
I. Sagittal section near the median plane through the larynx.
II. Oblique transverse section through larynx.
III. Almost horizontal section through larynx.
_A_ Arytenoid cartilage.
_C_ Cricoid cartilage.
_E_ Epiglottis.
_F_ False vocal cords.
_G_ Epiglotidean glands.
_H_ Hyoid.
_M_ Membranous floor of the larynx, cut obliquely.
_O_ Opening into root of lung.
_P_ Pre-arytenoid cartilage.
_V_ Vocal cord.
]
The anterior border is thin, the posterior thick and rounded.
Seen from in front (Fig. 206), the opening between the cords (_Rima
glottidis_) is slightly wider at each end than in the middle. The ends
of the concave posterior border are prolonged backwards and enclosed in
a fold of mucous membrane. Part of the tissue enclosed is unstriated
muscular fibre, which may be traced to the cricoid cartilage.
(2) [The *false vocal cords* (Figs. 202 and 206 _F_) are simply folds
of mucous membrane, which extend vertically on each side of the larynx
behind the true vocal cords; they do not extend so far towards the
median plane as do the true vocal cords.]
(3) [The *ventricles* of the larynx (Figs. 202 and 206) are two on each
side. The anterior ventricles are between the true vocal cords and the
arytenoid cartilages; they are open anteriorly, and closed by mucous
membrane posteriorly.
The posterior ventricles open towards the median plane, each presenting
an oval opening (Fig. 202), which widens outwards into a large cavity
(Fig. 206 _II_). The cavity is bounded in front by the base of the true
vocal cord, and the mucous membrane attached to it; posteriorly by
the false vocal cord, and externally by the cricoid cartilage and the
connective-tissue capsule of the larynx.]
(4) [The *mucous membrane* of the larynx varies in structure in various
parts of the organ. From the anterior opening of the larynx to the
posterior borders of the vocal cords it is lined with stratified
epithelium, which is firmly attached to the underlying structures by a
small amount of sub-epithelial tissue. This is especially well marked
on the vocal cords themselves.
Behind the vocal cords the mucous membrane is much more loosely
attached to the surrounding structures by an extremely vascular areolar
tissue. The epithelium is arranged in a single layer of columnar cells,
among which are numerous goblet-cells. In the more external parts of
the posterior ventricles, the mucous membrane is thrown into deep
folds and so forms polygonal acini. In the median line of the floor
of the larynx and behind the false vocal cords is a vertical fold of
mucous membrane, which increases in height and breadth as it proceeds
backwards towards the roots of the lungs. The mucous membrane behind
the true vocal cords is extremely vascular, in the most posterior
portion of the larynx the blood-vessels form a capillary network
exactly like that of the lungs.]
*e.* [The *epiglottis* (Fig. 206 _E_) is a small bilobed fold of mucous
membrane placed on the floor of the mouth in the median plane and
immediately in front of the aperture to the larynx. Between it and the
mucous membrane covering the arytenoid cartilages are a number of large
mucous glands (_G_). The epiglottis does not contain cartilage; it is,
however, constant in its appearance and sharply marked off from the
surrounding mucous membrane.]
II. THE LUNGS.
*a.* *General description.* The lungs are two large thin-walled sacs
(Figs. 185 and 204 _Lg_ and _Lg^1_). The roots of the lungs are
contracted at their origin from the larynx and then expand to form
two ellipsoid sacs, which terminate posteriorly in bluntly-pointed
ends. With the exception of their roots they lie entirely free in the
pleuro-peritoneal cavity, and are covered by the pleuro-peritoneal
membrane. In the recent state they have a bright red colour due to the
large supply of blood-vessels.
[Illustration: Fig. 207.
The Rima glottidis, seen from the front.
_G_ Rima glottidis.
_SB_ Vocal cords.
]
*b.* *Minute structure.*
(I) The *muscular tissue* of the lungs is for the most part arranged
in large bands, which form a coarse network on the deeper surface of
the organ; when seen in section[76] (Pl. II, Fig. 208 _A_, _B_) these
bands are found to be composed of well-developed involuntary muscular
fibres. Between the larger bands are smaller bands having a similar
arrangement. From these networks of muscular bands finer processes of
muscular tissue pass peripherally towards the surface of the organ, and
are attached to the thin and incomplete muscular layer found in the
wall of the lung (_C_).
[Footnote 76: See Plate II, Fig. 208.
Two sections from the lung of _Rana temporaria_; stained with borax
carmine.--G. H.
I. The lung dilated (Hartnack, Oc. I, Syst. 3).
II. The lung contracted (Hartnack, Oc. I, Syst. 7).
_A_ Band of muscle cut transversely.
_B_ Band of muscle cut longitudinally.
_C_ Muscular layer of surface.
]
(2) The *connective-tissue* of the lungs is present in only small
quantity, but is still sufficient to fill in the spaces between the
various muscular bands and the surface of the lung, and to invest the
whole of that surface. There is thus formed a series of pits, the
mouths of which open into the general cavity of the lung, while their
bases are at the surface. Through this connective-tissue course the
blood-vessels, nerves, and lymphatics. It contains numerous yellow
elastic fibres.
(3) The *blood-vessels* of the lungs. The pulmonary artery courses
along the outer surface of the lung to the apex, giving off, at right
angles, lateral branches in the whole of its course; these show a
tendency to be alternately larger and smaller. The lateral branches
divide and form a rich capillary network (T. Hoffmann).
The capillary network has very small meshes; the diameter of a given
mesh being frequently less than that of the capillary bounding it. The
meshes are rounded or polygonal in shape.
The pulmonary vein arises by lateral branches from this capillary
network; the branches join, at right angles, the main vein, which
courses from the apex of the lung along its inner surface to the root
of the organ.
(4) The *epithelium* of the lungs. Externally the lungs are covered
with a layer of endothelium derived from the peritoneum. Internally
the surface is covered with an epithelium which varies considerably in
different positions.
On the free borders of the muscular trabeculae forming the borders
of the alveoli is a short columnar ciliated epithelium (Fig. 208)
such epithelium is also found in the root of the lung; it contains
goblet-cells.
The alveoli, for the most part, are lined with a single layer of
tesselated epithelium; the cells are polygonal in outline, with finely
granular contents and a distinct nucleus: the average diameter of the
cells is from 0.0074 to 0.0108 mm., that of the nucleus 0.0054 mm.,
that of the nucleolus 0.0009 mm.; four to eight of such cells occupy
the space enclosed by one mesh of the capillary network (Eberth).
The epithelium rests on a structureless basement membrane, which is
continuous over the whole inner surface of the lung, whereas the
epithelium does not pass over the capillaries, and is therefore only
found in isolated patches in the areas enclosed by the capillaries
(Eberth).
In various isolated spots, small groups of short columnar or
goblet-cells are found in the tesselated epithelium (Eberth, Hoffmann).
(5) [The *lymphatics* of the lungs have been described by T. Hoffmann;
they form a network of vessels surrounding the larger blood-vessels:
from this branches are given off, which form a network of fine
canals through the whole of the lung; part of this secondary network
accompanies the blood-capillaries, but other portions run a separate
course. They communicate with the pleuro-peritoneal cavity.
(6) The *pigment-cells* are very numerous, branched, and large; they
accompany the lymphatics, and not the blood-vessels (T. Hoffmann).
(7) The *nerves* of the lungs (p. 172) course along the larger
blood-vessels, under the serous coat; the fibres are chiefly medullated
fibres (Egorow, Kandarazki). Non-medullated branches, which form
a plexus in each alveolus, are given off. The branches have small
triangular enlargements (ganglia), where they unite. The nerves are
accompanied by nerve-cells, which occur either singly or in groups.
Egorow describes the nerves as being distributed in three networks:
one for the mucous membrane and muscular trabeculae; a second for the
superficial muscular layer; and a third for the serous membrane.]
III. THE VOCAL SACS.
*a.* *General description.* The vocal sacs are a pair of sacs which
open in the floor of the mouth (Fig. 179 _S_); they are found only in
the males. When the animal croaks these sacs are dilated and act as
resonators; when so dilated the sacs force up the skin under the angle
of the mouth and tympanic membrane. In well-developed specimens they
are about as large as an average sized cherry. The skin covering the
sacs is extremely elastic, but is not directly attached to the sacs.
*b.* *Minute structure.* The sac consists of connective-tissue, with
a large proportion of yellow elastic fibre. Internally it is lined
with a flattened epithelium, and externally is covered with a layer of
striated muscular fibre, derived from the mylo-hyoid muscle (Fig. 209
_My_, _My^1_).
IV. THE THYMUS GLAND.
*a.* *General description.* The thymus gland (Fig. 210 _Th_) is
placed on each side behind the angle of the jaw; it is best exposed
by removing the skin behind the tympanic membrane and the angle of
the jaw, and then reflecting the _M. depressor mandibulae_ (_D.m._).
The gland is then found as an elongated, oval body, not quite 3 mm.
long, lying in the space between the _M. depressor mandibulae_ and
the _M. sternocleidomastoideus_ (_St_); it extends slightly beyond
the posterior border of the former muscle. The space also includes
connective-tissue, fat, and numerous vessels.
In _Rana temporaria_ this gland is spherical, much smaller, and placed
further behind on the _M. sternocleidomastoideus_, between the _M.
latissimus dorsi_ and the _M. deltoideus_ (Wiedersheim).
[Illustration: Fig. 209.
Dissection to show the vocal sac of the right side.
_HH_ Larger posterior cornua of the hyoid.
_HH^1_ Smaller posterior cornua of the hyoid.
_My_ Mylo-hyoid muscle.
_My^1_ Mylo-hyoid muscle continued on to the vocal sac.
_Thy_ Thyroid glands.
_VH_ Anterior cornua of the hyoid.
_Z_ Body of the hyoid.
]
*b.* *Minute structure* (Fig. 211).
[The gland is surrounded by a connective capsule, which is indented on
the inner surface to form a hilus through which blood-vessels course
into the organ.
The capsule sends in numerous fine trabeculae, which form a
connective-tissue skeleton such as is found in all lymphatic glands.
The corpuscles of the trabeculae possess elongated nuclei from 0.019 to
0.028 mm. in length, and 0.010 to 0.015 mm. in breadth (Tolldt). The
trabeculae support a network of blood-vessels.
The meshes of this sustentacular tissue are filled with *cells*; these
are:
(α) Lymphoid cells, rounded or oval, possessing a round nucleus and
nucleolus, and an extremely small amount of adhering protoplasm; the
size of the nucleus is from 0.011 to 0.015 mm. (Tolldt).
[Illustration: Fig. 210.
Dissection to show relations of the thymus gland.
_De._ M. deltoideus.
_D.m._ M. depressor mandibulae.
_L.d._ M. latissimus dorsi.
_St_ M. sternocleidomastoideus.
_Tf_ Tympanic membrane.
_Th_ Thymus gland.
]
[Illustration: Fig. 211.
From various sections from the thymus gland of _Rana esculenta_.--G. H.
I. Complete gland (Hartnack, Oc. I, Syst. 3).
_a_ Pigment-cells.
II. Portion of a section (Hartnack, Oc. I, Syst. 7) showing small
corpuscles of Hassall.
III. Portion of a section showing lobules with degenerating cells.
_a_ Capsule of lobe.
_b_ Lobules.
_c_ Large corpuscle of Hassall,
surrounded by normal tissue.
IV. Nerve-cell? (corpuscle of Hassall), after Fleischl. ]
(β) Corpuscles of Hassall (Fig. 211 II, III, and IV) are, as a rule,
large bodies, but are subject to much variation in size. Their general
appearance is seen in Fig. 211 III; they show a concentric striation
and usually enclose one or more smaller cells. They therefore closely
resemble similar corpuscles found in higher animals.
(γ) In many frogs the cellular structure of at least a part of the
gland seems to have undergone a degenerative stage (III). In such
cases the connective-tissue is increased in quantity, and marks off
portions of the section into small lobules (III) which are filled with
cells containing mucus or sometimes fat (III). Under what conditions
this degeneration, if such it be, takes place has not yet been
determined[77].
[Footnote 77: Only winter-frogs were at my disposal (translator).]
(δ) Large branched pigment-cells are found in the course of the larger
blood-vessels.
(ε) Watney describes also four varieties of ‘granular cells:’ 1.
polygonal or rounded; 2. vacuolated; 3. spheroidal masses; 4.
club-shaped masses attached to the blood-vessels. I have, however, not
been able to distinguish them.]
[Tolldt (_l. c._ 1868) described the lymphoid tissue and the
blood-vessels of this gland but did not find the corpuscles of
Hassall.
Fleischl (_l. c._ 1870) disputed Tolldt’s description; he
evidently found the corpuscles of Hassall (see Fig. 211 IV),
but he held them to be nerve-cells, and described them as such.
He was also of opinion that the blood-vessels open into the
intercellular spaces (as in the spleen). This has not been found
to be the case by any other observer. Watney (_l. c._ 1882) first
described the concentric corpuscles of Hassall as such.
Most writers describe the parenchyma as arranged in lobules. This
I have only seen in a part of the gland and under what I believe
to be pathological conditions.]
V. THE THYROID GLAND.
*a.* *General description.* A thyroid gland (Fig. 209 _Thy_) is found
on either side as a small, triangular, or oval, reddish-coloured body
on the dorsal surface of the _M. sternohyoideus_, just before it passes
between the _MM. genio-hyoidei_. It lies in the angle formed between
the larger and smaller posterior cornua of the hyoid (_HH_, _HH^1_).
It is easily found by the presence of a large number of vessels in its
neighbourhood, and especially by the large jugular vein, to the ventral
surface of which it is intimately attached.
Not uncommonly several smaller supplemental glands are found in the
rich anastomosis surrounding the organ.
The dorsal surface of the gland is lobulated, the ventral surface
flatter and convex. The glands of opposite sides are seldom symmetrical.
*b.* *Minute structure* (Fig. 212 I and II). [The gland possesses a
connective-tissue capsule, which sends in trabeculae to support the
vesicles of which the gland is composed.
The vesicles (I and II), which vary greatly in size, are closed
cavities, usually of a rounded or oval form, but sometimes branched
(Baber). Each vesicle is lined with a single layer of cubical or
slightly columnar epithelium (II, _a_), which rests on a delicate
basement-membrane of connective-tissue, placed between the epithelium
and the surrounding lymphatics (Baber).
Zeiss describes a delicate reticulum between the epithelial cells.
The vesicles always contain mucus (_b_), and are surrounded by a fine
anastomosis of blood-vessels (_c_).]
[Illustration: Fig. 212.
Minute structure of the thyroid gland of _Rana esculenta_.--G. H.
I. Section through the gland (Hartnack, Oc. I, Syst. 3).
II. Small portion of above (Hartnack, Oc. I, Syst. 7).
_a_ Epithelium lining the vesicles.
_b_ Mucus.
_c_ Blood-vessels, injected with blue mass.
]
VI. THE LYMPHATIC GLANDS OF THE HYOID REGION (TONSILS?).
*a.* [*General description.* These are two oval, reddish-coloured, soft
lymphatic glands, placed one on each side of the larynx. Frequently
they are divided into two or three lobes by more or less deep
fissures. They are constant in their occurrence, and are frequently
supplemented by one or more smaller glands; each gland has the
larynx on its inner side, the _Vena jugularis_ externally, the _M.
omohyoideus_ in front, and above the mucous membrane of the pharynx
(Tolldt).
*b.* *Minute structure.* The glands consist of dense lymphoid tissue
(Fig. 213), but possess in addition one or more large bodies (_a_)
which resemble lymphoid follicles in structure. Each is composed of a
dense mass of small cells; and the whole follicle is, as in similar
follicles of higher animals, sharply differentiated from the rest of
the organ.
The glands possess an extremely rich vascular supply, and are
frequently pierced by one or more large arterial trunks.
The mucous membrane covering the glands is thinner than that
immediately around, but is not perforated.]
[As far as I am aware, Tolldt is the only observer who describes
these glands; he makes no mention of the lymphoid follicles.]
[Illustration: Fig. 213.
Part of section through the lymphatic gland (tonsil?) of _Rana
esculenta_ (Hartnack, Oc. I, Syst. 13).--G. H.
_a_ Extremely large lymphoid follicle.
]
SECTION VII.
THE URINO-GENITAL SYSTEM, THE ADRENALS, AND THE FAT-BODIES.
THE URINO-GENITAL SYSTEM, ETC.
LITERATURE.
THE URINO-GENITAL ORGANS.
*Adami, J. G.*, On the nature of glomerular activity in the kidney.
Journ. of Physiol. 1886. Vol. VI, p. 382.
*Ankermann*, De moturo et evolutione filorum spermaticorum.
Regimonti, 1854.
*Ankermann*, Einiges über die Bewegung und Entwicklung der Samenfäden
des Frosches. Zeitsch. f. wiss. Zool. 1857. Vol. VIII, p. 129.
*Beale, L. S.*, On very fine nerve-fibres ramifying in certain
fibrous tissues, and of trunks and plexuses consisting entirely of
fine nerve-fibres in the bladder of the frog. Beale’s Archives of
Med. 1864. Vol. IV, pp. 19–251.
*Bergmann, C. G.*, De glandulis suprarenalis. Dissert. Göttingae,
1839.
*Bidder*, Vergleichende Anat. und histol. Untersuchungen über die
männlichen Geschlechts- und Harnwerkzeuge der nackten Amphibien.
Dorpat, 1846.
*Biondi, D.*, Die Entwicklung der Spermatozoiden. Arch. f. mik. Anat.
1885. Vol. XXV, p. 594.
*Bloomfield, J. E.*, The development of the Spermatozoa. Quart.
Journ. Micros. Sci. 1881. New Series. Vol. XXI, p. 415.
*Böttcher, A.*, Ueber den Bau und die Quellungsfähigkeit der
Froscheileiter. Virchow’s Arch. 1866. Vol. XXXVII, p. 174.
*Bouillot, J.*, Sur l’épithélium sécréteur du rein des Batrachiens.
Compt. rend. 1882. Vol. XCV, No. 14, pp. 603–604.
*Bourne, A. Gibbs*, On certain abnormalities in the common frog,
Rana temporaria. Quart. Journ. Micros. Sci. 1884. New Series.
Vol. XXIV, pp. 83–86.
*Bowman, W.*, Sur la structure et fonctions des glandules des reins
ou corpuscules de Malpighi. Annal. des Sci. Zool. 1843. Series II.
Vol. XIX, pp. 108–145.
*Bowman, W.*, On the structure of the Malpighian bodies of the
kidney, etc. Phil. Trans. 1842. Pt. I, pp. 57–80.
*Bowman, W.*, Ueber die Structur und den Nutzen der Malpighischen
Körper in den Nieren. Froriep’s Notizen, 1842. Vol. XXII, No. 21,
coll. 321–324.
*Bowman, W.*, Ueber die Structur und Functionen der Malpighischen
Körper in den Nieren. Froriep’s Notizen, 1843. Vol. XXV, No. 12,
col. 177.
*Brandt, A.*, Fragmentarische Bemerkungen über das Ovarium des
Frosches. Zeitsch. f. wiss. Zool. 1877. Vol. XXVIII, p. 575.
*Budge*, Harnreservoir der Wirbelthiere. Mittheil. aus d. naturw. V.
v. Neu-Pommern und Rügen. 1875, p. 103.
*Carus, C. G.*, and *Otto, A. W.*, Erläuterungstafeln zur
vergleichenden Anatomie. Leipzig, 1840.
*Crivelli e Maggi*, Alcuni cenni sovra lo studio dei corpi piangiati
delle Rane. Rendiconti del Reale Istituto Lombardo de scienze e
lettere. 1869. Second Series. Vol. II, p. 716.
*Della Chiaje*, Esistenza della glandule renala ne Batruci et ne
Pisci. Napoli, 1837.
*Drasch, O.*, Ueber das Vorkommen zweierlei verschiedener
Gefässknäuel in der Niere. Wiener Sitzungsb. 1878. Vol. LXXVI,
Part III, p. 79.
*Duncan, J.*, Ueber die Malpighischen Knäuel in der Froschniere.
Sitzungsb. d. Acad. zu Wien, 1867. Vol. LVI, Pt. II, p. 6.
*Duval, M.*, and *Wiet*, Ueber die Wanderung der Eier in die
Bauchhöhle beim Frosche. Gaz. de Paris, 1880. No. 17, p. 219.
*Duval, M.*, Recherches sur la Spermatogénèse chez la grenouille.
Revue Sci. nat. Montpellier, 1880. Vol. II, pp. 121–143.
*Ecker*, Der feinere Bau der Nebennieren, etc. 1846.
*Eimer, T.*, Untersuchungen über den Bau und die Bewegung der
Samenfäden. Verhandl. d. phys.-med. Gesell. in Würzburg, 1874.
Vol. VI, New Series, p. 93.
*Engelmann*, Zur Physiologie des Ureter. Pflüger’s Arch. f. d. ges.
Physiol. 1869. Vol. II p. 243.
*Fürbringer, M.*, Zur vergleichenden Anat. und Entwicklungsgesch. d.
Excretionsorgane der Vertebraten. Morph. Jahrb. Vol. IV.
*Fürbringer, M.*, Zur Entwicklung der Amphibienniere. Heidelberg,
1877.
*Gerlach, J.*, Beiträge zur Structurlehre der Niere. Arch. f. Anat.
u. Physiol. 1845, p. 378.
*Gibbes, H.*, On the structure of the Spermatozoon. Quart. Journ.
Micros. Sci. 1880. Vol. XX, p. 318.
*Goette, A.*, Entwicklungsgeschichte der Unke. Leipzig, 1875.
*Goette, A.*, Kurze Mittheilungen aus der Entwicklungsgeschichte der
Unke. Arch. f. mik. Anat. 1873. Vol. IX, p. 396.
*Grunau, H.*, Ueber das Flimmerepithel auf dem Bauchfell des
weiblichen Frosches und über den Eileiterbau desselben. Dissert.
Königsberg, 1875.
*Grünhagen, A.*, Untersuchungen über Samenentwickelung. Centralbl. f.
d. med. Wiss. 1885. Vol. XXIII, p. 481.
*Grünhagen, A.*, Ueber die Spermatogenese bei Rana fusca
(temporaria). Centralbl. f. d. med. Wiss. 1885. Vol. XXIII, p. 737.
*Gscheidlen, R.*, Zur Lehre v. d. Nervenendigung in den glatten
Muskelfasern. Arch. f. mik. Anat. 1877. Vol. XIV, p. 321.
*Heidenhain, R.*, Mikroskopische Beiträge zur Anatomie und
Physiologie der Nieren. Arch. f. mik. Anat. 1874. Vol. X, p. 1.
*Helmann*, Ueber die Entwicklung der Spermatozoen der Wirbelthiere.
Dissert. Dorpat, 1879.
*Henle, J.*, Zur Anatomie der Niere. Nachrichten v. d. k. Gesell.
d. Wissensch. z. Göttingen, 1862. Vol. X, pp. 4–12; and in
Abhandlungen, 1861–62, Vol. X, p. 223.
*Hoffmann, C. K.*, in Bronn’s Klassen und Ordnungen des Thierreichs.
Leipzig and Heidelberg, 1873–1879. Vol. VI.
*Hüfner*, Zur vergleichenden Anatomie und Physiologie der
Harncanälchen. Diss. Leipzig, 1866.
*Hyrtl*, Ueber die Injection der Wirbelthierniere, etc. Wiener Acad.
Sitzungsb. 1863. Vol. XLVII, Pt. I, p. 172.
*Jensen, O. S.*, Recherches sur la spermatogénèse. Archives de
Biologie, 1883. Vol. IV.
*Jensen, O. S.*, Ueber die Struktur der Samenkörper bei Säugethieren,
Vögeln, und Amphibien. Anat. Anzeiger. 1886.
*Knappe, E.*, Das Biddersche Organ. Morph. Jahrb. 1886. Vol. XI,
pp. 489–548.
*Kolessnikow, N.*, Ueber die Eierentwicklung bei Batrachiern und
Knochenfischen. Arch. f. mik. Anat. 1878. Vol. XV, p. 382.
*v. Kölliker, A.*, Gewebelehre. Fifth Edition.
*Langer, C.*, Ueber das Lymphgefässsystem des Frosches. Wiener Acad.
Sitzungsb. 1867. Vol. LV, Pt. I, p. 621.
*Lavdowsky, M.*, Ueber die Endigung der Nerven in der Harnblase des
Frosches. Centralbl. f. d. med. Wiss. 1871, p. 33.
*Lavdowsky, M.*, Die feinere Structur und die Nervenendigungen der
Froschharnblase. Arch. f. Anat. u. Physiol. 1872, p. 55.
*Lereboullet, A.*, Recherches sur l’anatomie des organes génitaux des
animaux vertébrés. Nov. acta Acad. Leop. Car. 1851. Vol. XXIII,
pp. 1–226.
*Leydig, F.*, Anatom.-histol. Untersuchungen über Fische und
Reptilien.
*Leydig, F.*, Lehrbuch der Histologie des Menschen und der Thiere.
Frankfurt, 1857, p. 508.
*Leydig, F.*, Untersuchungen zur Anatomie und Histologie der Thiere.
Bonn, 1883.
*List, J. H.*, Ueber Becherzellen im Blasenepithel des Frosches.
Wiener Sitzungsb. 1884, Vol. LXXXIX, Pt. III, pp. 186–210; also in
Arch. f. mik. Anat. 1887, Vol. XXIX, p. 147.
*List, J. H.*, Ueber Becherzellen im Blasenepithel des Frosches.
Zool. Anzeiger, 1884. No. 169, p. 328.
*List, J. H.*, Ueber einzellige Drüsen im Blasenepithele der
Amphibien. Biol. Centralbl. 1885. Vol. V, p. 499.
*Loos, P. A.*, Die Eiweissdrüsen d. Amphibien und Vögel. Zeitsch. f.
wiss. Zool. 1881. Vol. XXXV, pp. 478–504.
*Maier, R.*, Die Ganglien in den harnabführenden Wegen des Menschen
und einiger Thiere. Virchow’s Arch. 1881. Vol. LXXXV, pp. 49–71.
*Marcussen, J.*, Ueber die Cloake und Harnblase der Frösche. Bull.
der phys.-math. Acad. de St. Pétersbourg, 1853. Vol. XI.
*Marshall, A. M.*, On certain abnormal conditions of the reproductive
organs in the frog. Journ. of Anat. and Physiol. 1884. Vol. XVIII,
p. 121.
*Marshall, A. M.*, The frog. Manchester and London. 2nd Edit. 1885.
*Mecznikow, E.*, Zur vergleichenden Histologie der Niere. Göttinger
Nachrichten, 1866, p. 61.
*Meyer, F.*, Beitrag zur Anatomie des Urogenitalsystems der Selachier
und Amphibien. Sitzungsb. d. nat. Gesellsch. Leipzig. 1874, p. 38;
published 1875.
*Moleschott*, Ein histochemischer und ein histologischer Beitrag zur
Kenntniss der Nieren.
*Miescher*, Die Spermatozoen einiger Wirbelthiere. Verhandl. d.
naturf. Gesell. in Basel. 1878. Vol. VI.
*Neumann, E.*, Untersuchungen über die Entwickelung der
Spermatozoiden. Centralbl. f. d. med. Wiss. 1868. No. 24.
*Neumann, E.*, Untersuchungen über die Entwickelung der
Spermatozoiden. Arch. f. mik. Anat. 1875. Vol. XI, p. 292.
*Neumann* and *Grunau*, Drüsen der Froscheileiter. Arch. f. mik.
Anat. 1875. Vol. XI, p. 372.
*Nussbaum, N.*, Ueber die Niere der Wirbelthiere. Sitzungsber. Bonn,
1870.
*Nussbaum, N.*, Ueber die Endigung der Wimpertrichter in der
Anurenniere. Sitzungsb. d. niederrheinischen Gesell. in Bonn,
1877. Vol. XXXIV, p. 122.
*Nussbaum, N.*, Ueber den Bau und die Thätigkeit der Drüsen. Arch. f.
mik. Anat. 1886. Vol. XXVII, p. 442.
*Nussbaum, N.*, Ueber die Secretion der Niere und über die Verbindung
der Samen und harnbereitenden Drüsenschläuche in den Nieren der
Batrachier. Sitzungsb. d. niederrheinischen naturf. Gesell. in
Bonn, 1877. Vol. XXXIV, p. 277.
*Nussbaum, N.*, Fortgesetzte Untersuchungen über die Secretion d.
Niere. Pflüger’s Arch. f. d. ges. Physiol. 1878. Vol. XVII, p. 580.
*Nussbaum, N.*, Ueber die Endigung der Wimpertrichter der Niere der
Anuren. Zool. Anzeiger, 1880. No. 67, pp. 514–517.
*Nussbaum, N.*, Zur Differenzirung des Geschlechts im Thierreich.
Arch. f. mik. Anat. 1880. Vol. XVIII, p. 73.
*Peltier*, Sur les zoospermes de la grenouille. L’Institut. 1838.
Vol. VI.
*Perrault, C.*, De generatione ranarum fusca et bona dissertatio, in
Actis Eruditorum, 1687.
*Prévost*, Note sur les animalcules spermatiques de la grenouille et
de la Salamandre. Mémoires de la société phys. et d’hist. nat. de
Genève. Geneva and Paris, 1841–1842. Vol. IX, p. 289.
*Rathke, H.*, Beiträge zur Geschichte der Thierwelt, III Abth.; and
Neueste Schr. d. naturf. Gesell. in Danzig. 1825. Vol. I.
*Reger, R.*, Ueber die Malpighischen Knäuel der Nieren und ihre
sogenannten Capseln. Arch. f. Anat. u. Physiol. 1864, P. 537.
*Reichert*, On kidney. Jahresbericht über Anatomie in Arch. f. Anat.
u. Physiol. 1843, p. 220, etc.
*Remak*, Untersuchungen über die Entwicklung d. Wirbelthiere, p. 128.
*Retzius, G.*, Zur Kenntniss der Spermatozoen. Biol. Untersuchungen.
1881.
*Rideward, W. G.*, On an abnormal genital system in a male of the
common frog. Anat. Anz. 1888. Vol. III, p. 333.
*Robinson, C.*, Ueber die Lymphgefasse der abdominal Eingeweide des
Frosches. Froriep’s Notizen, 1846. No. 807, col. 225.
*Rösel, A. J.*, Historia naturalis ranarum nostralium. 1758, p. 28.
*Roth*, Untersuchungen über die Drüsensubstanz der Niere. Bern, 1864;
and Schweiz. Gesellsch. f. Heilkunde, 1864. Vol. III, pp. 1–34.
*Schiefferdecker*, Ueber einzellige Drüsen in der Blase der
Amphibien. Bericht. d. naturf. Ges. in Rostock, 1883.
*Schultze, F. E.*, Das Drüsenepithel der schlauchförmigen Drüsen
des Dünn- und Dickdarms und die Becherzellen (Cloaca of frog).
Centralbl. f. d. med. Wiss. 1866, p. 161.
*Schultze, M.*, Observationes nonnullae de ovorum ranarum
segmentatione. Bonn, 1863.
*Schultze, O.*, Untersuchungen über die Reifung und Befruchtung des
Amphibieneies. Zeitsch. f. wiss. Zool. 1887. Vol. XLV, pp. 177–226.
*Schweigger-Seidel, F.*, Ueber die Samenkörperchen und ihre
Entwicklung. Arch. f. mik. Anat. 1865. Vol. I, p. 309.
*Solger, B.*, Beiträge zur Kenntniss der Nieren und besonders der
Nierenpigmente der niederen Wirbelthiere. Abhandl. d. naturf. Ges.
zu Halle, 1882. Vol. XV.
*Spengel, J. W.*, Die Segmentalorgane der Amphibien. Verhandl. d.
phys.-med. Gesells. Würzburg. Vol. X, pp. 89–92.
*Spengel, J. W.*, Das Urogenitalsystem der Amphibien. Arbeiten aus d.
Zool. Inst. in Würzburg, 1876. Vol. III, pp. 1–114.
*Spengel, J. W.*, Wimpertrichter in der Amphibienniere. Centralbl. f.
d. med. Wiss. 1875, p. 369.
*Swammerdam, J.*, Bibblia naturae. Leydae, 1738. Vol. II, p. 796.
*Thompson, A.*, Article ‘Ovum’ in Todd’s Cyclopædia of Anatomy and
Physiology, London, 1879. Vol. V, p. 91.
*Tolotschinoff*, Ueber das Verhalten der Nerven zu den glatten
Muskelfasern der Froschharnblase. Arch. f. mik. Anat. 1869.
Vol. V, p. 509.
*Tornier, O.*, Ueber Bürstenbesätze am Drüsenepithel. Arch. f. mik.
Anat. 1886. Vol. XXVII, p. 181.
*v. la Valette St. George*, Spermatologische Beiträge. Arch. f. mik.
Anat. 1886, Vol. XXVII, p. 385; and in Stricker’s Gewebelehre,
Article ‘Hoden.’
*Valentin*, On kidney. Repertitorium, 1845. Vol. VIII, p. 92.
*Waldeyer, W.*, Eierstock und Ei. Ein Beitrag zur Anatomie und
Entwicklungsgesch. der Sexualorgane. Leipzig, 1870.
*Weldon, W. F. R.*, On the suprarenal bodies of vertebrata. Quart.
Journ. Micros. Sci. 1885. Vol. XXV, p. 137.
*v. Wittich, W.*, Beiträge zur morphologischen und histologischen
Entwicklung der Harn- und Geschlechtswerkzeuge der nackten
Amphibien. Zeitsch. f. wiss. Zool. 1853. Vol. IV, p. 152.
*Wolff, W.*, Die Innervation der glatten Muskulatur. Arch. f. mik.
Anat. 1882. Vol. XX, p. 361.
THE ADRENALS.
*Bergmann*, De glandulis suprarenalibus. Dissert. Göttingen, 1839.
*Ecker, A.*, Der feinere Bau der Nebennieren beim Menschen und den
vier Wirbel-thierklassen. Braunschweig, 1846.
*Frey, H.*, On the suprarenal capsules, in Todd’s Cyclopædia. London,
1849, p. 827.
*Giles, A. E.*, On the development of the fat-bodies in the frog.
Quart. Journ. Micros. Sci.
*Hoffmann, C. K.*, Bronn’s Klassen und Ordnungen des Thierreichs.
Heidelberg und Leipzig, 1873–1878. Vol. VI, p. 506.
*v. Kölliker, A.*, Handbuch der mikroskopischen Anatomie. Leipzig,
1854. Vol. II, p. 386.
*Leydig*, Lehrbuch der Histologie. Frankfurt a. M. 1857.
*Moers*, Ueber den feineren Bau der Nebennieren. Virchow’s Arch.
1864. Vol. XXIX, p. 336.
*Nagel*, Ueber die Structur der Nebennieren. Arch. f. Anat. u.
Physiol. 1830, p. 377.
THE FAT-BODIES.
*Carus*, Lehrbuch der Zootomie. Leipzig, 1818 (describes the
fat-bodies as suprarenals).
*Hoffmann, C. K.*, Bronn’s Klassen und Ordnungen des Thierreichs.
Heidelberg und Leipzig, 1873–1878. Vol. VI.
*Marshall, A. Milnes*, The frog. Manchester and London, 1884.
*v. Wittich, W.*, Beiträge zur morphologischen und histologischen
Entwicklung der Harn- und Geschlechtswerkzeuge der nackten
Amphibien. Zeitsch. f. wiss. Zool. 1853. Vol. IV, p. 152.
THE URINO-GENITAL SYSTEM, THE ADRENALS, ETC.
THE URINO-GENITAL SYSTEM.
By cutting through the meso-rectum the posterior caval vein is seen,
as a large vessel, arising by numerous transverse branches from the
ventral surfaces of the kidneys and testes (Fig. 214 _Cv_), lying in
the median line between the kidneys; by drawing it to one side the
dorsal aorta is brought into view (Fig. 214 _Ao_). The testes are
placed on the ventral surface of the kidneys, and together with the
fat-bodies conceal the anterior portions of these organs. The posterior
portions of the kidneys are covered by peritoneum only, and may by seen
without further dissection. The kidneys lie dorsal to the peritoneum,
and have this membrane on their ventral surfaces only; their dorsal
surfaces are in contact with the lumbo-sacral plexus.
The ureters extend from the anterior border of the eighth vertebra to
the middle of the urostyle, where they terminate by two orifices in the
dorsal wall of the cloaca (Fig. 184).
The testes are entirely surrounded by peritoneum, except a small part
(_Hilus_) of the inner surface, where the vessels and ducts enter.
[Illustration: Fig. 214.
The male urino-genital organs.
_Ao_ Aorta.
_Cl_ Cloaca.
_Cv_ Inferior vena cava.
_FK_ Fat-body.
_H_ Testis.
_N_ Kidney.
_S_, _S^1_ Openings of ureters.
_Ur_ Ureter.
_Vr_ Renal veins.
† Appearance of ureters on the ventral
surfaces of kidneys.
]
The urino-genital organs are arranged in the same manner in the
two sexes; the ovaries corresponding in position with the testes
(Fig. 214), that is, they are bilaterally symmetrical, and placed on
the ventral surfaces of the kidneys.
The oviducts (Fig. 224 _Ov_) lie externally to the kidneys and ovaries,
and course through the whole length of the trunk from the roots of the
lungs to the cloaca. The size of the ovaries and oviducts varies very
greatly according to the season of the year; at times, the kidneys may
be entirely hidden by them.
I. THE URINARY ORGANS.
A. The *kidneys*.
*a.* *General description.* Each kidney (Fig. 215) is a reddish-brown,
elongated organ, almost semilunar in shape; the inner border being
straight and the outer convex. The organ is flattened from above
downwards, and decreases in thickness towards either end. In animals
of average size the kidney is about 16 mm. long, and from 6 to 7 mm.
broad. The kidneys lie parallel to the vertebrae.
[Illustration: Fig. 215.
The right kidney, seen from the ventral surface.]
The outer border is smooth and even, except at its posterior third,
where a slight depression for the ureter exists; the inner border has
usually two or three well-marked notches, the hindermost of which is
the deepest (Fig. 215). Each notch is continued outwards as a groove,
traversing the whole breadth of the ventral surface and containing a
branch of the renal portal vein. The ventral surface is, as a whole,
slightly concave, grooved, and lobulated; the dorsal surface is smooth
and slightly convex.
*b.* [*Minute structure.* The kidney is enclosed in a thin capsule
of fibrous tissue (Fig. 220 _Bg_), which sends in fine trabeculae to
support the glandular structures and the blood-vessels.]
(1) The *blood-vessels* of the kidney are the renal veins, the renal
arteries, and the renal portal vein.
α. The renal portal vein (p. 247) courses along the outer border of
the posterior part of the kidney, and then along the outer margin of
the dorsal surface; in this course it gives off large branches, which
course inwards and forwards and supply numerous lateral twigs. These
anastomose to form a network of vessels on the dorsal surface of the
organ, from which very numerous large branches course downwards and
somewhat inwards to join corresponding branches of the renal veins
(Fig. 216 I).
[Illustration: Fig. 216.
The blood-vessels and lymphatics of the kidney.--G. H.
I. Transverse vertical section through kidney. Venous system blue;
arteries red (Hartnack, Oc. I, Syst. 3).
II. Part of a horizontal section through kidney. Venous system blue;
arteries red (Hartnack, Oc. I, Syst. 3).
III. Part of a transverse vertical section through kidney; lymphatics
blue (Hartnack, Oc. I, Syst. 7).
_A_ Ventral surface.
_B_ Dorsal surface.
_C_ Two arterial twigs uniting before
entering the Malpighian body.
]
β. The renal veins (p. 247) form a coarse plexus on the ventral surface
of the kidney, from this numerous large branches (Fig. 216 I) course
upwards and outwards.
The venous system between the renal portal veins on the dorsal surface,
and the renal veins on the ventral surface, are so large that they can
scarcely be named capillaries (Hyrtl).
γ. The renal arteries (p. 233) are distributed to the ventral surface
of the kidney; their mode of distribution varies in different parts of
the organ. A simple arrangement is that shown in Fig. 216 I, where a
branch traverses the breadth of the kidney and gives off branches to
the Malpighian corpuscles; in one case (_C_) I have seen two twigs
passing to the same corpuscle; as a rule, however, each Malpighian
corpuscle receives only one twig. A more general arrangement is that
the artery courses nearer the ventral surface and in a more winding
course, several twigs are then given off close together, from the
convex surface of one of the curves, and these course to their
respective corpuscles.
In the Malpighian corpuscle the arterial twig forms a series of loops
and then passes out to open abruptly into one of the branches of the
neighbouring venous anastomosis (Hyrtl).
(2) [The *Malpighian corpuscles* and their *capsules* (Figs. 216 I, 218
III). The corpuscles lie nearer the ventral than the dorsal surface.
They are rounded oval bodies, formed of loops of an arterial twig, held
together by a small amount of connective-tissue. Each corpuscle is
enclosed in a capsule, which it incompletely fills (Fig. 217)[78].
[Footnote 78: See Plate II.
Portions of two transverse vertical sections through the kidney.--G. H.
I. Kidney of _Rana esculenta_, partial injection of the
uriniferous tubes with silver nitrate (Hartnack, Oc. I, Syst. 7).
II. Kidney of _Rana temporaria_, stained with borax-carmine
(Hartnack, Oc. I, Syst. 7).
]
The capsules are formed of connective-tissue and lined with a
flattened epithelium (Fig. 218 III): according to Duncan the fibrous
coat is arranged in two layers (III _a_). Towards the opening of the
uriniferous tube the epithelium increases in thickness.
According to Hyrtl, the corpuscles are arranged in two layers, a more
superficial one and a deeper one; and are of two sizes, the larger
being as a rule the more superficial (ventral).]
(3) [The *uriniferous tubes* (Figs. 217 and 218). Each tube originates
at a narrow opening on the dorsal surface of a Malpighian capsule. The
tube gradually widens and is lined with a short rounded or cubical
epithelium (Roth), (Fig. 218 III); each epithelial cell bearing a small
number of extremely small cilia (Bowman, Kölliker, Duncan, and others).
The cilia of the cells nearest the capsule are directed towards
it (Heidenhain), those of the cells further away have an opposite
direction (Spengel). This portion of the tube is known as the neck; it
courses dorsalwards.
The second portion of the tube (_Tubulus contortus_), (Fig. 218 III,
IX, and XII) has a very tortuous course in the dorsal part of the
kidney, and then winds towards the ventral surface. This portion is
lined with columnar epithelium, which has granular contents, and
possesses large distinct nuclei. The cells of this part of the
kidney are usually more or less coloured with a golden-yellow pigment.
According to Tornier it bears short cilia (Fig. 218 XIV).
[Illustration: Fig. 218.
Various preparations to show the structure of the uriniferous tubes,
etc.
I. Three portions of the uriniferous tubes from _Rana esculenta_, from
a natural injection with sulphindigotate of sodium (Hartnack, Oc. I,
Syst. 3).--G. H.
II. From the third part of a uriniferous tube; short ciliated
epithelium, borax-carmine (Hartnack, Oc. I, Syst. 7).--G. H.
III. A Malpighian corpuscle and capsule; shows the capsule of two
layers at _a_. After Duncan.
IV. Part of uriniferous tube after natural injection with
sulphindigotate of sodium (Hartnack, Oc. I, Syst. 3).--G. H.
V. Transverse section of one of the larger branches of the ureter, from
_Rana esculenta_ (Hartnack, Oc. I, Syst. 7).--G. H.
VI. Epithelial lining of the ureter itself while still in the kidney
(Hartnack, Oc. I, Syst. 7).--G. H.
VII. Portion of a uriniferous collecting-tube from section in Fig. 217
I, stained with silver (Hartnack, Oc. I, Syst. 7).--G. H.
VIII. Renal epithelium; _a_ to _b_, tubulus contortus; _b_ to _c_,
third portion of uriniferous tube; _c_ to _d_, fourth portion of tube.
After Heidenhain (enlarged 210 times).
IX. Ciliated cells of the neck, after Duncan.
X. Isolated rod-cells of _Triton taeniatus_, after Heidenhain.
XI. Isolated rod-cells, after Heidenhain (enlarged 300 times).
XII. Isolated cells of the neck, after Heidenhain (enlarged 210 times).
XIII. Portion of the fourth part of a uriniferous tube, after
Heidenhain (enlarged 300 times).
XIV. Ciliated epithelium of tubulus contortus, after Tornier (magnified
550 times).
XV. From kidney of _Rana temporaria_, after Spengel.
_a_ Uriniferous tube opening into seminiferous duct.
_b_ Dilated seminiferous duct cut longitudinally.
_c_ Vas efferens cut transversely.
]
The third portion corresponds with the narrow limb of Henle’s loop; it
is lined with ciliated epithelium (Fig. 218 VIII, _b_ to _c_), similar
to that in the neck of the tube.
The fourth portion (Fig. 218 VIII, _c_ to _d_, and XIII) represents
the wider limb of Henle’s loop. It has a winding course in the
ventral part of the kidney, and then ascends dorsally to open into a
collecting-tube. The fourth part of the tube is lined with a short,
columnar epithelium (Fig. 218 VIII, _c_ to _d_), which has a clear,
cuticular, free border, large nucleus, and a peculiar arrangement of
the protoplasm, which shows a rod-like structure (Fig. 218 XI).
The collecting-tubes course transversely near the dorsal surface of the
kidney (Fig. 217), and the uriniferous tubes meet them at right-angles.
They are lined with a short polygonal epithelium (Fig. 218 VII).
The *peritoneal funnels* of the kidney (nephrostomes). Spengel,
Meyer, and Hoffmann describe these funnels as existing in the
frog; according to them they open on the ventral surface by
narrow apertures, and each is connected, by a vertical tubule,
with the fourth part of the uriniferous tube (Spengel), but
according to Nussbaum, with the neck of the tube. According to
Spengel and Meyer the number of these funnels is in Rana from 250
to 360.
According to Wiedersheim the funnels hang free from the ventral
surface like so many parasites attached by fine filaments, and do
_not_ open on the surface.
Heidenhain (Arch. f. mik. Anat., Vol. X) was unable to find these
organs.
Being unable to find any trace of these organs in the kidneys of
either R. temporaria or R. esculenta, in microscopic sections
or in teased preparations, I inserted canulae into the ureters
of both male and female specimens of both species, and injected
the uriniferous tubes with a solution of Berlin blue. Although
the tubules were, in some cases, completely injected, in no
case could I find any trace of a peritoneal funnel, nor was
there any escape of the solution from the kidney as would be the
case if the funnels were open and communicated with any part of
the uriniferous tubes. Even when the pressure was increased to
the extent of a column of 25 cm. high of the injection-mass,
no escape took place from the surface of the kidney, though
in numerous cases the uriniferous tubes were ruptured by the
abnormally high pressure.
Properly dissected frogs were placed in 0.6% sodium chloride
solution, in which finely divided gamboge was suspended. No trace
of ciliary action was, in any case, found on either surface of
the kidneys.
One may therefore conclude that if the peritoneal funnels exist
in the adult frog (1) they are very difficult to find; (2) they
do not form a free communicating path between any part of the
uriniferous tubes and the abdominal cavity; (3) their superficial
terminations have no free cilia. As before stated I have found no
trace of any such organs.
The *lobules* of the kidney. When treated with proper reagents the
kidney shows a marked tendency to separate into lobules (Fig. 219 I).
The *lymphatics* of the kidney (Fig. 216 III[79]) form an irregular
network of fine canals with elongated meshes. They run chiefly in the
direction of the blood-vessels. The large vessels, which supply the
kidney, are surrounded by large lymphatics.]
[Footnote 79: See Plate II.
Two portions from a gold preparation of the kidney of _Rana
esculenta_.--G. H.
I. Showing the tendency to split into lobules.
II. Nerve-fibres accompanying the blood-vessels.
_a_ Blood-vessels.
_b_ Nerves.
]
The *nerves* of the kidney (Fig. 219 II)[79]. Little is known of these.
Nerve-fibres have been traced alongside the larger blood-vessel through
the greater part of the kidney.
B. The *ureters*.
*a.* *General description.* In the males the ureters are, at the same
time, the seminiferous ducts. Each ureter commences on the dorsal
surface of the kidney by bifurcating branches, which are continuous
with the collecting-tubes of the kidney. In the anterior two-thirds of
the kidney the ureter is wholly on the dorsal surface; at the junction
of the middle and posterior thirds it winds round to the outer border
of the kidney (Fig. 214 _Ur_), and there lies in a groove accompanied
by the renal portal vein (Fig. 220 _Ur_ and _Va_), the two organs being
intimately attached to the kidney substance and enclosed by the fibrous
capsule (_Bg_).
This portion of the ureter possesses a spindle-shaped enlargement,
which represents the _Receptaculum seminis_. In _Rana temporaria_ the
_Receptaculum seminis_ forms a large saccular dilatation.
In its further course the ureter runs backwards and slightly inwards,
converging with its fellow of the opposite side; the ureters lie free
in the abdominal cavity, and terminate by two openings placed side by
side in a groove on the dorsal wall of the cloaca (Fig. 214 _S_, _S^1_).
In females the ureters are intimately attached to the dilated oviduct,
immediately after leaving the kidney; they pursue a similar course to
those of the males, but are attached to the oviduct in the whole of
their course to the cloaca.
*b. Minute structure.* The ureter is a tube composed of
connective-tissue and involuntary muscular fibre, and lined with a
mucous membrane. The mucous membrane is thrown into longitudinal folds,
and consists, in the larger tubes, of two or three layers of epithelium
(Fig. 218 V), that on the free surface is columnar; the deeper cells
being rounded or polygonal. The larger branches of the ureter are lined
with columnar epithelium (Fig. 218 VI), with small intervening cells.
In some parts of the branches the columnar epithelium bears short cilia.
No glands have been found in the ureter or _Receptaculum seminis_; in
_Rana temporaria_, however, the _Receptaculum seminis_ possesses large,
branching mucous glands (Wiedersheim).
[Illustration: Fig. 220.
Transverse section of the kidney, enlarged.
_Bg_ Connective-tissue capsule.
_D_ Dorsal surface.
_NC_ Renal parenchyma.
_Ur_ Ureter.
_V_ Ventral surface.
_Va_ Renal portal vein.
]
C. The *bladder*.
*a.* *General description.* The urinary bladder (Fig. 185 _HB_) is
closely attached to the ventral wall of the cloaca and is easily
distended from that organ. In relation to the animal it is of very
large size; in consequence of its being contracted in the middle it
has two lobes, which may be of unequal size. The organ is somewhat
heart-shaped (Figs. 184 and 185), with the narrow neck attached to
the cloaca, into which it opens by a smaller aperture on the ventral
surface. The aperture is surrounded by a small fold of mucous membrane.
*b.* [*Minute structure.* The urinary bladder is bounded by a thin,
transparent wall, lined internally with mucous membrane, and covered
externally by peritoneum.
(1) The muscular coat is formed of a network of fine bands of
unstriated muscular fibre (Fig. 221); it is supported and completed by
a connective-tissue layer, rich in connective-tissue corpuscles and
yellow elastic fibres.
(2) The peritoneal coat is a single layer of endothelial cells derived
from the peritoneum and resting on a very thin layer of subperitoneal
tissue.
[Illustration: Fig. 221.
Various preparations from the bladder.
I. Silver preparation of the mucous membrane; seen from the surface.
After List (enlarged 400 times).
_a_ Cells of the surface.
_d_ Goblet-cells.
_e_ Young cells.
II. Vertical section of the mucous membrane; after List (enlarged 600
times).
_a_ Cells of upper layer.
_b_ Cells of middle layer.
_c_ Cells of lower layer.
III. Large multicellular ganglion; after Wolff.
IV. Vertical section from a silver preparation of the mucous membrane;
after List (enlarged 600 times).
_a_ Upper layer.
_b_ Middle layer.
_c_ Lower layer.
_d_ Goblet-cells.
V. Small ganglion of bladder; after Wolff.
_a_ Non-medullated nerve-fibre leading to ganglion.
_b_ Process of a ganglion cell.
]
(3) The mucous coat is formed of epithelium resting on a layer of
loose, areolar tissue. The epithelium (Fig. 221 I, II, and IV) is
arranged in three layers: the cells of the uppermost (II and IV, _a_)
always present a flat or convex border to the cavity of the organ; seen
from their free surfaces (I) they have polygonal outlines intermixed
with round apertures belonging to goblet-cells, the remaining surfaces
of these cells are serrated. The cells of the middle layer (II and IV,
_b_) are polygonal in outline, they are not so tall as the cells of the
layer above; all their borders are serrated. The cells of the deepest
layer (II and IV, _c_) are more or less pointed above where they
project between the cells of the second layer; their lowest surfaces
are flattened towards the subepithelial tissue, and all their surfaces
are serrated.
The cells of all three layers possess a cell-wall, and finely granular
contents, and each cell has a large oval nucleus (List).
The goblet-cells (Fig. 221 I and IV, _d_) vary very much in shape;
they are always more or less rounded in outline: they vary greatly
in size (from 190 µ to 54 µ in length); some possess ‘feet’ or basal
prolongations, in others these are absent. They usually open freely
by rounded apertures on the surface of the mucous membrane, but are
sometimes closed. The nucleus is placed towards the base of the cell
and surrounded by a smaller or larger amount of protoplasm. These
cells usually extend into the middle layer of the epithelium, and they
probably constitute unicellular mucous glands (List).
(4) The *blood-vessels* of the urinary bladder (p. 235) are very
numerous and run in very tortuous courses; they are accompanied by
large lymphatics and by nerves.
(5) The *nerves* of the urinary bladder (p. 191) are of both medullated
and non-medullated fibres, which course together towards their points
of distribution; the non-medullated fibres are, however, much more
frequent than the medullated fibres (Wolff).
The non-medullated nerve-fibres stand in close relation with the
nerve-ganglia of the bladder. These ganglia may be unicellular, or
composed of groups of nerve-cells; the cells vary considerably in
shape, round, oval, triangular, and other forms being equally frequent
in their occurrence; to some extent the form appears to depend upon the
number and position of the processes of the cells. The diameter of the
cells varies from 0.05 mm. to 0.1 mm.; the nucleus has a diameter of
0.025 mm., that of the nucleolus measures 0.005 mm. (Wolff).
The cells may be unipolar or multipolar; the former are however rare.
The processes of these cells supply the muscle-fibres (Fig. 221 V,
_a_), and other non-medullated processes connect the cells with the
nerves (V, _b_ (Wolff)).
The number of muscular fibres is far in excess of the number of the
fibres of distribution of the ganglia; Wolff hence concludes that the
nervous impulse may pass from one muscle-fibre to another.]
II. THE REPRODUCTIVE ORGANS.
A. The *male reproductive organs* are the testes and their ducts.
*a.* *General description.* The relations of the testes have already
been given (p. 234); the organs vary much in shape and size in
different individuals and with the different seasons; when greatest
they are spherical, or of a rounded oval form, occasionally cone-shaped
or pear-shaped. The surface of the testes is not smooth, but presents a
series of convexities, each corresponding to a lobule of the gland. At
the _hilus_ on the inner border the vessels pass to and from the organ,
and the _Vasa efferentia_ leave the testis.
[Illustration: Fig. 222.
The male reproductive organs (enlarged).
_CC_ Vasa efferentia within the kidney.
_H_ Testis.
_LL_ Collecting-tube at inner border of kidney.
_N_ Kidney.
_Ne_ Vasa efferentia within the mesorchium.
_Ur_ Ureter.
† Vasa efferentia ending blindly.
]
The number of _Vasa efferentia_ (Fig. 222 I and II) is subject to
considerable variation, not only in different animals, but on the two
sides of the same animal. In some cases these ducts form a network (I),
in other cases this is absent (II); usually the ducts
[Illustration: Fig. 223.
Various preparations from the testis.
I. Various stages of the spermatozoa; from testis of _Rana temporaria_.
After Neumann.
II. Section from testis of _Rana esculenta_ (Hartnack, Oc. I, Syst.
7).--G. H.
_a_ Thin connective-tissue capsule.
_b_ Trabeculae.
_c_ and _d_ Seminiferous tubes.
III. From testis of _Rana temporaria_. After Neumann.
_x_ Rounded epithelium of seminiferous tubes.
_y_ Spermatoblasts.
IV. Surface view of seminiferous tube of _Rana temporaria_. After
Neumann.
_a_ Granular protoplasmic feet of spermatoblasts.
_b_ Rounded epithelium.
]
bifurcate at acute angles, just before entering the kidney. Most of
the tubes so formed open into the collecting-tube; a few, however,
end blindly in the mesorchium (I, †). The course of the _Vasa
efferentia_ from the testis is first inwards, within the mesorchium;
on reaching the kidney they curve dorsalwards between that organ
and the corresponding testis: the ducts then travel in the ventral
surface of the kidney towards its inner border, where they open into
a longitudinal canal (Bidder), (Fig. 222 I, _L_). Just before their
terminations each duct has an enlargement (I, _C_), the exact import of
which is unknown (see also Fig. 218 XV).
The collecting-tubes open into the ureter at the hinder extremity of
the kidney.
*b.* [*Minute structure.* The testis possesses a thin connective-tissue
capsule underneath its peritoneal covering (Fig. 223 II, _a_); this
sends in trabeculae (_b_) towards the centre of the organ, and so
encloses the separate lobules. Each seminiferous tube arises from an
elongated irregular sinus placed towards the middle of the organ;
the tubes (_c_) are slightly convoluted in their course towards the
periphery, near which they branch (Spengel). The tubes are from
0.16 mm. to 0.12 mm. in diameter (Kölliker), and are lined with two
kinds of cells (Fig. 222 III); the cells (_x_) nearer the periphery are
rounded and have large rounded nuclei, the diameters of which vary from
0.013 to 0.02 mm.; these again possess large and distinct nucleoli. The
other cells (_y_) are of elongated, spindle-shaped form; and have oval
nuclei, with an average length of 0.016 mm. and an average breadth of
0.005 mm. (Neumann).
The rounded cells lie in groups which vary in thickness and
arrangement, and are often compressed so as to have polygonal outlines.
The spindle cells are arranged so as to radiate from the lumen of the
tube to the periphery, at an angle which varies from 45 to 90 degrees;
these are the spermatoblasts.
The various changes which the spermatoblasts undergo in the formation
of spermatozoa will easily be understood by reference to Fig. 223
I, _a_ to _k_, where _i_ and _k_ represent the fully developed
spermatozoa. These have three parts, head, middle part, and tail,
the respective lengths of which in the two species are, according to
Neumann, the following:--
Head. Middle part. Tail.
Rana esculenta 0.0140 mm. 0.0025 mm. 0.040 mm.
Rana temporaria 0.0066 " 0.0330 " 0.045 "
At the hilus of the testis the rounded cells of the seminiferous tubes
are gradually modified to form short cylindrical cells (0.01 mm. long
and 0.006 mm. broad), the spindle cells being absent (Neumann). The
_Vasa efferentia_ are also lined with a similar columnar epithelium
(Spengel).]
B. The *female reproductive organs*.
The position of these organs has already been given (p. 335).
I. The *ovaries*.
*a.* *General description.*
Each sac-like ovary (Fig. 224) is subdivided by thin-walled septa into
numerous complete chambers, to the inner walls of which the ova are
attached. The walls of adjacent sacs are intimately attached to each
other, and the subdivision corresponds with the external lobulated
appearance of the organ. According to Spengel the number of lobules
is about fifteen (Rathke nine to thirteen, Brandt nine). Whether this
segmentation of the ovary corresponds with the segmentation of the body
has not been determined (Spengel). No part corresponding with Bidder’s
organ has been found in _Rana esculenta_.
During the breeding season the ovaries undergo an extraordinary
increase in size so as to occupy the greater part of the body-cavity
and to displace the other viscera. The ovaries are entirely surrounded
by peritoneum.
[Illustration: Fig. 224.
The female reproductive organs; the ovary of the right side has been
removed.
_N_ Kidney.
_O.T._ Opening of the oviduct into pleuro-peritoneal cavity.
_Ov_ Oviduct.
_Ova_ Ovary.
_P_ Opening of oviduct into the cloaca.
_S_, _S^1_ Openings of the ureters.
_Ut_ Dilated hinder portion of the oviduct.
† Groove in which ureters lie.
* Fold in groove separating the openings of the ureters.
]
*b.* *Minute structure.* [The layer of peritoneum covering the
ovary possesses cilia (Thiry), the ciliated cells being arranged in
isolated patches (Schweigger-Seidel, Waldeyer) on the ventral surface
of the organ, and on the mesovarium; these patches are sometimes
united by very fine connecting lines of ciliated epithelium;
the ciliated epithelium is always sharply marked off from that
surrounding it (Kolessnikow). Under the peritoneum is a thin layer
of connective-tissue, which is prolonged inwards to form the septa
above-described. To these septa are attached the ova.
Between the connective-tissue layer and the peritoneum are isolated
patches of germinal epithelium (Fig. 225 IV); these are easily
distinguished, by the rounded outlines of their cells, from the
surrounding epithelial cells (Waldeyer, Kolessnikow). These patches
of germinal epithelium measure from 0.093–0.186 mm. in diameter; the
germinal cells average 0.0139–0.0232 mm. in diameter (Kolessnikow).
The patches are most numerous on the outer surface of the ovary, and
particularly so near the mesovarium.
The follicles contained in the ovary have a connective-tissue coat
developed in a manner similar to that of higher animals; the primordial
ova which they contain have large nuclei (0.0325 mm.). The epithelium
of the follicles has an average diameter of 0.0232–0.0325 mm.
(Kolessnikow).
Schultze’s description of the ovaries (_l. c._) varies considerably
from that of Waldeyer and Kolessnikow. Briefly he describes the ovaries
as a series of sacs separated by and lined externally and internally by
endothelium; between these two layers are found the germinal epithelium
and follicles: the structures being held together by an extremely
minute quantity of connective-tissue.]
II. The *oviducts*.
*a.* *General description.* In young animals the oviducts are quite
straight, thin-walled, and of small calibre. During the breeding
season, however, they undergo an immense increase in size, and become
much convoluted; in this state they are forced in between the other
abdominal viscera, and usually cover the whole of the kidneys, and
sometimes even part of the ovaries (Fig. 224 _Ov_).
The openings of the oviducts into the pleuro-peritoneal cavity
(p. 304) are semilunar slits, directed inwards and lined with ciliated
epithelium (p. 306).
Immediately behind this opening (_Ostium abdominale_) the oviduct is
contracted, and is there narrower than in the rest of its length;
beyond this it expands, and then retains an even size nearly to its
hinder extremity, where it suddenly expands (Fig. 224 _Ut_). This
dilatation gradually diminishes in size as it proceeds backwards
towards the cloaca, into which each tube opens on a small papilla.
The dilated portions of the tubes lie close together, but do not
communicate with each other; the opening of the right tube is always
slightly behind that of the left side (Fig. 224 _P_). From the
papillae, into which the oviducts open, a fold of mucous membrane
extends backwards on the dorsal surface of the cloaca to meet its
fellow of the opposite side at an acute angle (Fig. 224 *). The
orifices of the ureters are placed within these folds.
[Illustration: Fig. 225.
Preparations from ovary and oviduct.
I. Ciliated epithelium and goblet-cells of the oviduct; after Neumann.
II. Isolated goblet-cells and secretory cells from oviduct; after
Neumann.
_a_, _b_, _c_ Goblet-cells.
_d_, _e_, _f_ Secretory cells after treatment with Müller’s fluid.
_x_ Stoma of secretory cells.
III. Surface view of the ovary; after Kolessnikow.
_a_ Peritoneal endothelium.
_b_ Germinal epithelium.
]
*b.* *Minute structure.*
(1) The *tubular portion* of the oviduct has three walls: a peritoneal
covering with sub-peritoneal tissue (_a_); a glandular layer (_b_); and
an epithelial lining (_c_). Of these the glandular layer forms by far
the thickest layer, especially during the breeding season, when it is
much increased in thickness. It consists of long cylindrical glands,
often bifurcated at their blind, peritoneal ends. The epithelial cells,
with which they are lined, have the power of absorbing more than a
hundred times their own weight of water (Boettcher). This layer is
absent at the anterior opening of the oviduct.
The cells have an average diameter of 0.012 mm., the lumen of the
individual glands 0.1 mm. (in spirit-hardened specimens, Neumann).
The cells contain small rounded bodies of very varying size, which
may exist singly, grouped, or even arranged in rows; they swell on
the addition of water. Each cell possesses, in addition, an oval,
granular, distinct nucleus. When treated with Müller’s fluid many of
the secretory cells have the appearances shown in Fig. 225 II, _d_,
_e_, _f_; they each possess an opening (_x_), (Neumann).
According to Neumann the great power of absorbing water, which the
oviducts possess, is due to the presence of these bodies, which he
names ‘colloid granules.’ The mucous secretion of these glands passes
into the oviduct and surrounds the eggs on their passage towards the
cloaca: it is due to this secretion that the egg-spawn is so extremely
slippery and difficult to handle.
The inner surface of the oviducts is lined with a ciliated, columnar
epithelium (Fig. 225 I), containing numerous goblet-cells (I and II).
(2) The *dilated portion* of the oviduct has much thinner walls than
the anterior, narrower portion; the glands cease abruptly at the
junction of the two parts. The outer coat also contains unstriated
muscular fibre; the inner surface is lined with ciliated epithelium
similar to that of the anterior portion.
The *lymphatics* of the oviducts form a net with polygonal meshes on
their outer surfaces; from this branches pass inwards in the spaces
between adjacent glands to the inner surface, where a network with
elongated meshes is formed (Langer).
C. [The *Cloaca*.
*a.* *General description.* The cloaca is a short tube lying beneath
the urostyle; anteriorly it receives the openings of the ureters,
rectum, and bladder; and in the female the openings of the oviducts, in
addition: posteriorly it terminates at the anus.
*b.* *Minute structure.* The cloaca is lined internally with a mucous
membrane resembling that of the rectum, _e.g._ a simple layer of
columnar epithelium, which rests on a submucous, areolar layer.
The outer walls consist of a thick superficial, longitudinal muscular
layer, and a deeper, ill-developed, transverse muscular layer.
*c.* *Special muscles of the cloaca.*
(1) The _M. sphincter ani_ surrounds the end of the cloaca from the
anus to the tip of the urostyle. It consists of striated muscle.
(2) The _M. compressor cloacae_ arises from the tip of the urostyle,
and is inserted into the hinder end of the rectum; it is also attached
to the symphysis of the iliac bones; from this point a few fibres pass
to the anus (Hoffmann).]
III. THE ADRENALS.
*a.* *General description.* The adrenals are small yellow bodies
attached to the renal veins on the ventral surface of the kidney,
towards its outer border.
*b.* [*Minute structure.* The superficial layer of the adrenals
consists of solid, rounded, or elongated groups of polygonal cells,
containing numerous fat-granules; these represent the cortical
substance of the corresponding organs of higher animals. The medullary
part is present only in small quantity; it consists of small groups of
polygonal cells, placed between trabeculae of connective-tissue; both
trabeculae and cell-groups are covered with an endothelium. The whole
organ is surrounded by a connective-tissue capsule, which sends in
trabeculae to support the parenchyma (Hoffmann).
No nerves have been traced into these organs (Eberth).]
[Illustration: Fig. 226.
The male urino-genital organs.
_Ao_ Aorta.
_Cl_ Cloaca.
_Cv_ Inferior vena cava.
_FK_ Fat-body.
_N_ Kidney.
_S, S1_ Openings of ureters.
_T_ Testis.
_Ur_ Ureter.
_Vr_ Renal veins.
† Appearance of ureters on the ventral
surfaces of kidneys.
]
IV. THE FAT-BODIES.
*a.* *General description.* The fat-bodies (Fig. 226) are bright
yellow, lobulated bodies, placed in front of the testes and ovaries
respectively. The greater portion of each organ lies parallel to
the long axis of the body, and from its anterior, posterior, and
external borders are given off finger-like processes; these may divide
dichotomously either near the base or more peripherally. The external
processes are much the longest, and in the male often conceal the
greater part of the testis (Fig. 226 _FK_). The organs vary greatly in
size with the season of the year.
[Illustration: Fig. 227.
Two preparations from the fat-body of _Rana esculenta_[80].--G. H.
[Footnote 80: From specimens collected in November.]
I. Section of fat-body, stained with borax-carmine (Hartnack, Oc. I,
Syst. 7).
_b_ Fat-cells.
_c_ Adenoid tissue.
II. Three lobes of fat-body of _Rana esculenta_; coarsely injected
(Hartnack, Oc. I, Syst. 3).
Arteries striped. Veins shaded.
]
*b.* [*Minute structure.* Each organ is completely surrounded by
peritoneum, under which is a very fine layer of connective-tissue. The
interior of the organ (Fig. 227 I) consists of large fat-cells with
small patches of adenoid tissue interspersed. The organs are extremely
vascular; each lobe has a main artery which gives off lateral branches:
each of these immediately divides to form two vessels, which run in
opposite directions and almost parallel with the main stem; the vessels
then break up into a fine network of capillaries.]
SECTION VIII.
THE SKIN AND THE SENSE-ORGANS.
THE SKIN AND THE SENSE-ORGANS.
LITERATURE.
I. THE SKIN.
*Ascherson*, Ueber die Hautdrüsen der Frösche. Arch. f. Anat. u.
Physiol. 1810, p. 15.
*Axmann*, Beiträge zur mikroskopischen Anatomie und Physiologie des
Ganglien-nervensystems. 1853.
*de Betta*, Erpétologia delle provincie Venete e del Tirolo
meridionale. 1857.
*Biesiadecki*, Ueber Basenbildung und Epithelregeneration an
der Schwimmhaut des Frosches. Untersuchungen aus d. Krakauer
path.-anatom. Institut. 1872, pp. 60–84. Abstract in Centralbl. f.
d. med. Wiss. 1873, No. 7, p. 106.
*Bimmermann, E. H.*, Ueber den Einfluss der Nerven auf die
Pigmentzellen des Frosches. Dissert. Strasburg, 1878.
*Bimmermann, E. H.*, Ueber den Einfluss der Nerven auf die
Pigmentzellen des Frosches. Centralbl. f. d. med. Wiss. 1879,
p. 545.
*de Blainville, M. H. M. Ducrotay*, De l’Organisation des animaux.
Paris, 1822, pp. 142, 225.
*Bolaw*, Beitrag zur Kenntniss der Amphibienhaut. Göttingen, 1866.
*Bruch*, Beiträge zur Naturgeschichte und Classification der nackten
Amphibien. Würzburger naturwiss. Zeitsch. 1864. Vol. III.
*Brücke*, Untersuchungen über den Farbenwechsel des afrikanischen
Chamaeleon. Sitzungsb. der Wiener Acad. 1852. Vol. IV, p. 196.
*Bugnion*, Recherches sur les organes sensitifs qui se trouvent dans
l’épiderme du Protée et de l’Axolotl. Dissert. Zürich.
*Canini, A.*, Die Endigungen der Nerven in der Haut des
Froschlarvenschwanzes. Arch. f. Anat. u. Physiol. 1880,
pp. 143–153.
*Ciaccio, J. V.*, Intorno alla minuta fabbrica della pella della
Rana esculenta. Palermo, 1866. Giornale di Scienze naturali ed
economiche. Vol. II, pp. 103–158.
*Ciaccio, J. V.*, On the distribution of the nerves to the skin of
the frog, with physiological remarks on the ganglia connected
with the cerebro-spinal nerves. Trans. Micros. Soc. London, 1864.
Vol. XII, pp. 15–31.
*Czermak, J. N.*, Ueber die Hautnerven des Frosches. Arch. f. Anat.
u. Physiol. 1849, p. 252.
*Da Collin*, Danemarks Froer og Tudser. Naturhist. Tidsskrift. 1870.
*Dewitz*, Ueber das verschiedene Aussehen der gereizten und ruhenden
Drüsen im Sehenballe des Laubfrosches. Biol. Centralbl. 1883,
p. 558.
*Dogiel*, Neue Untersuchungen über den pupillenerweiterden Muskel,
etc. Arch. f. mik. Anat. 1886. Vol. XXVII, p. 403.
*Duméril* et *Bibron*, Erpétologie générale. 1841. Vol. VIII.
*Eberth, C. J.*, Untersuchungen zur normalen und path. Anatomie der
Froschhaut. Leipzig, 1869.
*Eberth, C. J.*, Zur Entwickelung der Gewebe im Schwanze der
Froschlarven. Arch. f. mik. Anat. 1866. Vol. II, pp. 490–503.
*Eckhard*, Ueber den Bau der Hautdrüsen der Kröten und die
Abhängigkeit der Entleerung ihres Secretes vom centralen
Nervensystem. Arch. f. Anat. u. Physiol. 1849.
*Ehrmann, S.*, Ueber Nervenendigungen in den Pigmentzellen der
Froschhaut. Sitzungsb. der Wiener Acad. 1882. Vol. LXXXIV,
Pt. III, pp. 165–170.
*Engelmann, T. W.*, Pflüger’s Arch. f. d. ges. Physiol. 1871,
Vol. IV, p. 321, and 1872, Vol. V, pp. 500–513. (Contractile
glands in skin of frog.)
*Harless, E.*, Ueber die Chromatophoren des Frosches. Zeitsch. f.
wiss. Zool. 1854, Vol. V, p. 372; also in Münchener Gelehrten
Anzeiger, 1853, No. 35.
*Harley, G.*, On the organs of cutaneous respiration; principally
on those of Rana temporaria. Trans. Micros. Soc. London, 1857.
Vol. V, p. 148.
*Hensche, A.*, Ueber die Drüsen und glatten Muskeln in der äusseren
Haut von Rana temporaria. Zeitsch. f. wiss. Zool. 1856. Vol. VII,
p. 273.
*Henslow*, Way in which toads shed their skin. Annals of Nat.
History, 1850, p. 69.
*Hoffmann, C. K.*, Bronn’s Klassen und Ordnungen des Thierreichs.
Leipzig und Heidelberg, 1873–1878. Vol. VI.
*Huber, O.*, Ueber Brustwarzen bei Rana temporaria, L. Zeitsch. f.
wiss. Zool. 1887. Vol. XLV, p. 664.
*Huizinga, D.*, Untersuchungen über die Innervation der Gefäsze in
der Schwimmhaut des Frosches. Pflüger’s Arch. 1875. Vol. XI,
p. 207.
*Huxley, T. H.*, Tegumentary organs. Todd and Bowman’s Cyclopædia of
Anat. and Physiol. p. 500.
*Klein, E.*, On the lymphatic system of the skin and mucous
membranes. Quart. Journ. Micros. Sci. 1881. Vol. XXI, pp. 379–406.
*Kölliker, A.*, Stiftchenzellen in der Epidermis von Froschlarven.
Zoolog. Anzeiger. 1885.
*Krause*, Handbuch der Gewebelehre. 1862.
*Krukenberg, C. F. W.*, Die Hautfarbstoffe der Amphibien, in
Vergleich. Physiol. Studien, by same author, 1882, pp. 43–49.
*Kutschenko, N.*, Ueber die Krappfärbung der Froschgewebe. Arch. f.
mik. Anat. 1882. Vol. XXVIII, pp. 360–364.
*Langer*, Ueber das Lymphgefässsystem des Frosches. Wiener
Sitzungsberichte. 1867. Vol. LV, pp. 593–636.
*Langerhans*, Anat.-hist. Untersuchungen über Fische und Reptilien.
Berlin, 1853. Journal de Medicine. Vol. XI.
*Leboucq, H.*, Recherches sur le développement et la terminaison des
nerfs chez les larves des Batraciens. Bull. de l’acad. roy. de
Belgique. 1876. Vol. XLI, p. 4.
*Leydig, F.*, Histologisch-anatomische Untersuchungen über Fische und
Reptilien. 1853.
*Leydig, F.*, Tastkörperchen und Muskelstruktur. Arch. f. Anat. u.
Physiol. 1856, pp. 150–159.
*Leydig, F.*, Lehrbuch der Histologie. 1857.
*Leydig, F.*, Ueber die Nervenendigung in den sogenannten
Schleimkanälen der Fische und über entsprechende Organe der durch
Kiemen athmenden Amphibien. Arch. f. Anat. u. Physiol. 1861.
*Leydig, F.*, Ueber die Organe eines sechsten Sinnes. Nov. act. acad.
Leop. Carol. 1868. Vol. XXXIV, pp. 1–102.
*Leydig, F.*, Ueber die allgemeinen Bedeckungen der Amphibien. Arch.
f. mik. Anat. 1876. Vol. XII, p. 119.
*Leydig, F.*, Ueber die Schleichenlurche. Zeitsch. f. wiss. Zool.
Vol. XVIII.
*Leydig, F.*, Ueber die Schwanzflosse, Tastkörperchen und Endorgane
der Nerven bei Batrachiern. Arch. f. mik. Anat. 1876. Vol. XII,
pp. 513–527.
*Leydig, F.*, Die anuren Batrachier der deutschen Fauna. Bonn, 1877,
p. 123.
*Lister, J.*, On the cutaneous pigmentary system of the frog. Phil.
Trans. 1857. Vol. CXLVIII, p. 627.
*Macallum, A. B.*, The nerve terminations in the cutaneous epithelium
of the tadpole. Quart. Journ. Micros. Sci. 1886. Vol. XXVI, p. 53.
*Mayer, A.*, Ueber das Epithelium bei den Amphibien. Froriep’s
Notizen, 1839. Vol. IX, coll. 49–51.
*Menke*, Rana rubita, Linn. Zeitschr. Isis von Oken. 1827. Vol. XX,
p. 172.
*Merkel*, Ueber die Endigungen der sensiblen Nerven in der Haut der
Wirbelthiere. Rostock, 1880.
*Meyer*, Ueber die Abhängigkeit der Gefässe und Pigmentzellen beim
Frosch von dem Nerveneinfluss. Virchow’s Arch. 1854. Vol. VI,
p. 581.
*Openchowski, T.*, Histologisches zur Innervation der Drüsen.
Pflüger’s Arch. 1882. Vol. XXVII, pp. 223–232.
*Pfitzner, W.*, Die Epidermis der Amphibien. Morph. Jahrb. 1880.
Vol. VI, p. 469.
*Rainey*, On the structure of the cutaneous follicles of the toad.
Quart. Journ. Micros. Sci. Vol. III, p. 257.
*Roesel*, Historia natur. rana. nostrat. Nürnberg, 1758, p. 3, etc.
*Rudneff*, Ueber die epidermiodale Schicht der Froschhaut. Arch. f.
mik. Anat. 1865. Vol. I, p. 295.
*Sattler, E. E.*, Die Verwendung des Lapisstiftes zur Untersuchung
der Epithelien. Arch. f. mik. Anat. 1882. Vol. XXI, p. 672.
*Schneider*, Historia amphibiorum. 1739.
*Schultze, F. E.*, Epithel und Drüsenzellen. Arch. f. mik. Anat.
1867. Vol. III, p. 145.
*Schultze, F. E.*, Ueber cuticulare Bildungen und Verhornung von
Epithelzellen bei den Wirbelthieren. Arch. f. mik. Anat. 1869.
Vol. V, p. 295.
*Schultze, M.*, Ueber die Nervenendigung in der Netzhaut des Auges
bei Menschen und Thieren. Centralbl. f. med. Wiss. 1869, p. 885.
*Stieda, L.*, Ueber den Bau der Haut des Frosches. Arch. f. Anat. u.
Physiol. 1865, pp. 52–66.
*Stricker, S.*, and *Spina, A.*, Untersuchungen über die mechan.
Leistungen d. acinösen Drüsen. Wiener med. Jahrb. 1880, p. 355;
und Wiener Sitzungsb. 1880. (Skin and Membrana nictitans.)
*Swammerdam, J.*, Biblia naturae. Vol. II, p. 808.
*Szcesny*, Beiträge zur Kenntniss der Textur der Froschhaut. Dissert.
inaug. Dorpat, 1867.
*Turner*, Way in which toads shed their skins. Annals of Nat.
History, 1850, p. 430.
*Wagner, R.*, Handwörterbuch der Physiologie. Vol. III, p. 389.
*Walter*, Ueber die Drüsen des Daumenballens des Froschmännchens.
Verhandl. d. naturf. Vereins der pr. Rheinlande und Westphalen.
1851, p. 351.
*v. Wittich*, Die grüne Farbe der Haut unserer Frösche, etc. Arch. f.
Anat. u. Physiol. 1854, p. 41.
*v. Wittich*, Entgegnung auf Herm. Harless’s über die Chromatophoren
des Frosches. Arch. f. Anat. u. Physiol. 1854, p. 264.
II. SPECIAL ORGANS OF TACTILE SENSATION.
_a. The lateral sense-organs._
*Beard, J.*, On the segmental sense-organs of the lateral line and on
the morphology of the vertebrate auditory organs. Zool. Anz. 1884.
Vol. VII, p. 162.
*Bugnion, E.*, Recherches sur les organes sensitifs qui se trouvent
dans l’épiderme du Protée et de l’Axolotl. Dissert. inaug.
Zürich. Tire du Boll. No. 7, de la société vaucloise des Sc. nat.
Vol. XII. Lausanne, 1873. Verhandl. d. schweiz. naturforsch.
Gesells. Zürich, 1873. Vol. LVI, p. 49.
*Froriep, A.*, Ueber Anlagen von Sinnesorganen am Facialis,
Glossopharyngeus und Vagus. Arch. f. Anat. u. Physiol. 1885.
*Hoffmann, C. K.*, Bronn’s Klassen und Ordnungen des Thierreichs.
Leipzig and Heidelberg, 1873–1878.
*v. Kölliker, A.*, Ueber neue Sinnesorgane von Froschlarven.
Sitzungsb. Würzburg. 1885, p. 79.
*Krause, W.*, Die Nervenendigung innerhalb der terminal Körperchen.
Arch. f. mik. Anat. 1880. Vol. XIX, pp. 53–137.
*Leydig, F.*, Ueber die Organe eines sechsten Sinnes. Nova acta Acad.
Leopold. Carol. Dresden, 1868. Vol. XXXIV, pp. 1–102.
*Leydig, F.*, Ueber die allgemeinen Bedeckungen der Amphibien. Arch.
f. mik. Anat. 1875. Vol. XII, pp. 513–527.
*Leydig, F.*, Ueber Tastkörperchen und Muskelstructur. Arch. f. Anat.
u. Physiol. 1856, p. 150.
*Malbranc, M.*, Bemerkung betreffend die Sinnesorgane der Seitenlinie
der Amphibien. Centralbl. f. med. Wiss. 1875, p. 5.
*Malbranc, M.*, Von der Seitenlinie und ihren Sinnesorganen bei
Amphibien. Zeitsch. f. wiss. Zool. 1876. Vol. XXVI, pp. 24–86.
*Schultze, F. E.*, Ueber die Nervenendigung in den sogenannten
Schleimkanälen der Fische und über entsprechende Organe der durch
Kiemen athmenden Amphibien. Arch. f. Anat. u. Physiol. 1861,
p. 759.
*Schultze, F. E.*, Ueber die Sinnesorgane der Seitenlinie bei Fischen
und Amphibien. Arch. f. mik. Anat. 1870. Vol. VI, p. 62.
_b. The touch-corpuscles of Golgi._
*Golgi, C.*, Della terminazione dei nervi nei tendini e di un
nuovo apparato nervoso terminale musculo-tendineo. Atti della
Società Italiana di scienze naturali. Milan, 1879. Vol. XXI; and
abstracted in Centralbl. f. med. Wiss. 1879, p. 725.
*Golgi, C.*, Intorno alla distribuzione e terminazione dei nervi nei
tendini dell’ uomo e di altri vertebrali. Estratto dai Rendiconti
del R. Istituto Lombardo. Serie II. Vol. XI. Fasc. IX. Milan,
1878. Abstract in Centralbl. f. med. Wiss. 1879. Vol. 41, p. 725.
*Löwe, L.*, Ueber eine eigenthümliche Art von Gelenknervenkörperchen
beim Frosch. Arch. f. mik. Anat. 1880. Vol. XVI, p. 613.
III. THE ORGANS OF TASTE.
*Beale, L. S.*, New observations upon the minute anatomy of the
frog’s tongue. Phil. Trans. 1865, p. 443.
*Biedermann, W.*, Ueber morphologische Veränderungen der Zungendrüsen
des Frosches, etc. Wiener acad. Sitzungsb. 1882. Vol. LXXXVI,
Pt. III, p. 67.
*Billroth, T.*, Ueber die Epithelzellen der Froschzunge, etc. Arch.
f. Anat. u. Physiol. 1858, p. 159.
*Engelmann, T. W.*, Ueber die Endigungsweise der Geschmacksnerven des
Frosches. Centralbl. f. med. Wiss. 1867, p. 785.
*Engelmann, T. W.*, Ueber die Endigungen der Geschmacksnerven in der
Zunge des Frosches. Zeitsch. f. wiss. Zool. 1868. Vol. XVIII,
p. 142.
*Engelmann, T. W.*, Die Geschmacksorgane. Stricker’s Handbuch der
Gewebelehre. 1872.
*Fixsen, C.*, De linguae raninae structura. Dorpat, 1857.
*Gottschau, M.*, Ueber Geschmacksorgane der Wirbelthiere. Biol.
Centralbl. 1882, pp. 240–248.
*Hartmann, R.*, Ueber die Endigungsweise der Nerven in den Papillae
fungiformes der Froschzunge. Arch. f. Anat. u. Physiol. 1863,
p. 634.
*Hoyer*, Mikroskopische Untersuchungen über die Zunge des Frosches.
Arch. f. Anat. u. Physiol. 1859, p. 481.
*Hoyer*, Ueber die Epithelzellen der Froschzunge, etc. Arch. f. Anat.
u. Physiol. 1858, p. 163; also in Deutscher Klinik, 1857. No. 21.
*Hyrtl*, Ueber abwickelbare Gefässknäuel in der Zunge der Batrachier.
Wiener Acad. Sitzungsb. 1863. Vol. XLVIII, Pt. I, p. 437.
*Key, E. A.*, Ueber die Endigungsweise des Geschmacksnerven in der
Zunge des Frosches. Arch. f. Anat. u. Physiol. 1861, p. 329.
*Lépine* (On the nerve supply of the glands of the tongue). Arbeiten
aus d. physiol. Anstalt zu Leipzig, 1870, p. 113.
*Molin, R.*, Ueber die Theilung der Nervenprimitivröhren in den
Papillae fungiformes der Froschzunge. Wiener acad. Sitzungsb.
1849. Vol. III, p. 183.
*Schultze, F. E.*, Die Geschmacksorgane der Froschlarven. Arch. f.
mik. Anat. 1870. Vol. VI, p. 407.
*Waller, A.*, Minute structure of the organ of taste in vertebrate
animals. Proc. Roy. Soc. 1848. Vol. V, p. 751.
*Waller, A.*, Minute structure of the papillae and nerves of the
tongue of the frog and toad. Phil. Trans. 1848. Pt. I, p. 139.
*Waller, A.*, Microscopic examination of some of the principal
tissues of the tongue, etc. Phil. Mag. 1847. Vol. XXX, p. 277.
IV. THE NOSE.
*Babuchin*, Das Geruchsorgan, in Stricker’s Handbuch der Gewebelehre.
1872, p. 964.
*de Blainville, M. H. M. Ducrotay*, L’Organisation des animaux.
Paris, 1822, p. 328.
*Blaue, J.*, Untersuchungen über den Bau der Nasenschleimhaut bei
Fischen und Amphibien, namentlich über Endknorpel als Endapparate
des Nervus olfactorius. Arch. f. mik. Anat. 1884. Vol. XXX,
pp. 231–309. Zool. Anzeiger. Vol. V, pp. 657–680.
*Born, G.*, Ueber die Nasenhöhlen und den Thränennasengang der
Amphibien. Morph. Jahrb. 1875. Vol. II, p. 4.
*Born, G.*, Ueber die Nasenhöhlen und den Thränennasengang der
Amphibien. Breslau. Habilit.-Schrift. 1877.
*Born, G.*, Die Nasenhöhlen und der Thränennasengang der amnioten
Wirbelthiere. Morph. Jahrb. 1879. Vol. V, p. 62. 1882. Vol. VIII,
pp. 188–232.
*v. Brunn*, Die Membrana limitans olfactoria. Centralbl. f. med.
Wiss. 1874, p. 709.
*v. Brunn*, Untersuchungen über das Riechepithel. Arch. f. mik. Anat.
1875. Vol. XI, pp. 468–478.
*v. Brunn*, Weitere Untersuchungen über das Riechepithel u. sein
Verhalten zum N. olfactorius. Arch. f. mik. Anat. 1880. Vol. XVII,
p. 141.
*Cisoff*, Zur Kenntniss der Regio olfactoria. Centralbl. f. med.
Wiss. 1874, pp. 689–691.
*Cisoff*, Zur Frage über die Endigung der Riechnerven beim Frosche.
Arbeiten der naturf. Gesells. an der Universität Kassan. 1879.
Vol. VIII (in Russian).
*Clarke, J. Lockhart*, Ueber den Bau des Bulbus olfactorius und der
Geruchsschleimhaut. Zeitsch. f. wiss. Zool. 1862. Vol. XI, p. 31.
*Colossanti*, Untersuchungen über die Durchschneidung des N.
olfactorius bei Fröschen. Arch. f. Anat. u. Physiol. 1875.
*Dirkinck-Holmfield-Christmas, J.*, Experimentalle Undersögelen
Bijgningen. Nordiskt medicinskt Arkiv., 1883. Vol. XXVI, pp. 50–60.
*Dogiel, A.*, Ueber die Drüsen der Nasenschleimhaut, besonders die
Bowmanschen Drüsen. Arch. f. mik. Anat.
*Dogiel, A.*, Ueber den Bau des Geruchsorgans bei Garroirren,
Knochenfischen, und Amphibien. Arch. f. mik. Anat. 1887.
Vol. XXIX, p. 74.
*Dogiel, A.*, Ueber den Bau des Geruchsorgans bei Fischen und
Amphibien. Biol. Centralbl. Vol. I, pp. 428–431.
*Dogiel, A.*, Ueber die Drüsen d. Regio olfactoria. Arch. f. mik.
Anat. 1885. Vol. XXVI, p. 50.
*Ecker, E.*, Bericht über die Verhandl. der Gesellschaft für Beförd.
der Naturw. zu Freiburg, 1855, p. 199; and in Zeitsch. f. wiss.
Zool. 1856, Vol. VIII, p. 303.
*Eckhard, C.*, Beiträge zur Anatomie und Physiologie. Pt. I, 1855,
p. 77.
*Eckhard, C.*, Ueber die Endigungsweise der Geruchsnerven. Beiträge
zur Anat. u. Physiol. Giessen, 1882. Vol. I, p. 77.
*Erichsen, J.*, De textura nervi olfactorii ejusque ramorum. Dissert.
inaug. 1857.
*Exner, S.*, Untersuchungen über die Riechschleimhaut des Frosches.
Sitzungsb. der Wiener Acad. 1871. Vol. LXIII, Pt. II, p. 44.
*Exner, S.*, Weitere Studien über die Structur der Riechschleimhaut
bei Wirbelthieren. Sitzungsb. der Wiener Acad. 1872. Vol. LXV,
Pt. III, p. 7.
*Exner, S.*, Fortgesetzte Studien über die Endigungsweise des
Geruchsnerven. Sitzungsb. der Wiener Acad. 1878. Vol. LXXVI,
Pt. III, p. 171.
*Gastaldi*, Nuove Ricerche sovra la terminazione del nervo olfatt.
Mem. della reale Acad. della scienze di Torino. 1858. Vol. XVII,
Series II, p. 369.
*Hoffmann*, Lehrbuch der Anatomie der Sinnesorgane.
*Hoffmann, C. K.*, Ondersockingen over den anat. bouw van de membrana
olfactoria en het periph. uitiende van den Nervus olfactorius.
Dissert. inaug. 1866.
*Hoffmann, C. K.*, Amphibia in Bronn’s Klassen und Ordnungen
des Thierreichs. Leipzig und Heidelberg, 1873–1878. Vol. VI,
pp. 335–347.
*Horn, H.*, Ueber die Endschlingen des Geruchsnerven (nervus
olfactorius) der Rana temporaria. Arch. f. Anat. u. Physiol. 1850.
*Hoyer, H.*, De tunica mucosa narium textura. Dissert. inaug. Berol.,
1857.
*Hoyer, H.*, Ueber die mikroskopischen Verhältnisse der
Nasenschleimhaut, etc. Arch. f. Anat. u. Physiol. 1860, p. 50.
*Langer, C.*, Ueber das Lymphgefässsystem des Frosches. Wiener Acad.
Sitzungsb. 1867. Vol. LV, Pt. I, p. 615.
*Legal, E.*, Die Nasenhöhlen und der Thränennasengang der amnioten
Wirbelthiere. Morph. Jahrb. 1882. Vol. VIII, p. 353.
*Martin*, Studies from the physiological laboratory in the University
of Cambridge. Pt. I. 1873.
*Paschutin, V.*, Ueber den Bau der Schleimhaut der Regio olfactorio
beim Frosch. Medicinisky Wjestnik. 1872. Nos. 38–40.
*Paschutin, V.*, Ueber den Bau der Schleimhaut der Regio olfactoria
des Frosches. Arbeiten aus d. phys. Laborat. Leipzig, 1873.
*Paulsen, E.*, Ueber die Drüsen der Nasenschleimhaut besonders
die Bowman’schen Drüsen. Arch. f. mik. Anat. 1886. Vol. XXVI,
pp. 307–321.
*Piersol, G. A.*, Beiträge zur Histologie der Harderschen Drüsen der
Amphibien. Arch. f. mik. Anat. 1887. Vol. XXIX, p. 594.
*Reichert, B.*, Arch. f. Anat. u. Physiol. 1857, p. 39. Bericht.
*Schultze, M.*, Ueber die Endigungsweise des Geruchsnerven und die
Epithelial-gebilde der Nasenschleimhaut. Monatsb. Acad. z. Berlin.
1856, p. 504.
*Schultze, M.*, Untersuchungen über den Bau der Nasenschleimhaut,
namentlich die Structur und Endigungsweise der Geruchsnerven
bei dem Menschen und den Wirbelthieren. Halle, 1862. Vol. VII,
pp. 32–41; also published in Berlin, 1875. Abstract in Centralbl.
f. med. Wiss. 1863, p. 97.
*Seeberg*, Disq. microsc. de textura membr. pitnit. nasi. Dorpat,
1855. Dissert. inaug.
*Stirling, W.*, and *Macdonald*, The minute structure of the palatine
nerves of the frog and the termination of nerves in blood-vessels
and glands. Journ. of Anat. and Physiol. 1884. Vol. XVII, p. 293.
*Wiedersheim, R.*, Ueber die Kopfdrüsen der Amphibien. Sitzungsb. d.
phys.-med. Gesell. in Würzburg, 1876. Febr. 5.
*Wiedersheim, R.*, Die Kopfdrüsen der geschwänzten Amphibien und die
Glandula intermaxillaris der Anuren. Zeitsch. f. wiss. Zool. 1876.
Vol. XXVII, pp. 1–50.
*Wiedersheim, R.*, Lehrbuch der vergl. Anatomie der Wirbelthiere.
Pt. I. Jena, 1882.
V. THE EAR.
*Chatin, J.*, Recherches pour servir a l’histoire du noyau dans
l’épithelin auditif des batrachiens. Annales des sciences nat.
Zool. 1883. Vol. XVI, Series VI, Art. No. 2.
*Comparetti, A.*, in gymnasio patavino observationes anatomicae de
aure interna comparatae. Patavii, 1789.
*Crombie, J. M.*, On the membrana tympani. Journ. of Anat. and
Physiol. 1883, pp. 523–536.
*Cuvier, G.*, Leçons d’anatomie comparée. Paris, 1800. Vol. II.
*Deiters, O.*, Ueber das innere Gehörorgan der Amphibien. Arch. f.
Anat. u. Physiol. 1862, p. 277.
*Eberth, C. J.*, Zur Kenntniss der Verbreitung der glatten
Muskelfasern (Tympanic membrane). Zeitsch. f. wiss. Zool. 1863.
Vol. XII, p. 364.
*Ferré*, Étude sur la crête auditive chez les vertébrés. Ann. Sci.
Nat. Bordeaux. Vol. I, No. III.
*Hasse, C.*, Die Histologie des Bogenapparates und des Steinsacks der
Frösche. Zeitsch. f. wiss. Zool. 1868. Vol. XVIII, p. 71.
*Hasse, C.*, Das Gehörorgan der Frösche. Zeitsch. f. wiss. Zool.
1868. Vol. XVIII, p. 359.
*Hasse, C.*, Das knöcherne Labyrinth der Frösche. Anatomische
Studien, 2nd Pt. 1872, p. 377.
*Hasse, C.*, Die vergleichende Morphologie und Histologie des
häutigen Gehörorgans der Wirbelthiere. Supplement to the
Anatomische Studien. Vol. I, 1873.
*Hasse, C.*, Die Lymphbahnen des inneren Ohres der Wirbelthiere. In
the Anatomische Studien of Hasse, 1873. No. XIX.
*Hasse, C.*, Das Gehörorgan der Wirbelthiere von Gustav Retzius.
Arch. f. Ohrenheilk. 1884. Vol. XXI, pp. 314–324.
*Hoffmann*, Lehrbuch der Anatomie der Sinnesorgane.
*Hoffmann*, Bronn’s Klassen und Ordnungen des Thierreichs. Leipzig
and Heidelberg, 1873–1878. Vol. VI, pp. 304–335.
*Ibsen, J.*, Anatomiske Undersögelser over orets Labyrinth. Udgivet
vet P. L. Panum. Kjöbenhawn, 1846 (abstract in Virchow and
Hirsch’s Jahresb. 1881, p. 88).
*Kuhn*, Ueber das häutige Labyrinth der Amphibien. Arch. f. mik.
Anat. 1880. Vol. XVII, pp. 479–550.
*Kuhn*, Zur Anatomie des inneren Ohres der Wirbelthiere. Compt. rend.
du III Congrès internat. d’Otologie à Bàle, 1884, pp. 228–238.
*Leydig, F.*, Lehrbuch der Histologie des Menschen und der Thiere.
Frankfurt a. M. 1857.
*Leydig, F.*, Ueber neuere den Aquaeductus vestibuli des Menschen
und der Thiere betreffende Forschungen. Sitzungsb. d.
Niederrheinischen naturf. Gesellsch. in Bonn, 1874. Vol. XXXIV,
p. 124.
*Moldenhauer*, Vergleichende Histologie des Trommelfells. Arch. f.
Ohrenheilk. 1878, p. 1.
*Pappenheim, S.*, Ueber Verbreitung der Flimmerbewegung. Arch. f.
Anat. u. Physiol. 1840, p. 533.
*Retzius, G.*, On hörselnervens ändningssätt i maculae och cristae
acusticae. Nordiskt medicinskt arkiv. 1871. Vol. III.
*Retzius, G.*, Zur Kenntniss der Morphologie des inneren Ohres bei
Wirbelthieren. Nord. Med. Ark. 1880. Vol. XII, No. 12.
*Retzius, G.*, Zur Kenntniss des Gehörorgans der Wirbelthiere. Arch.
f. Anat. u. Physiol. 1880, pp. 235–244.
*Retzius, G.*, Das Gehörorgan der Wirbelthiere. Pts. I and II, 1881.
Stockholm.
*Retzius, G.*, Das Gehörorgan der Wirbelthiere. Congr. internat. de
Copenhagen. Anatomy, p. 29.
*Retzius, G.*, Das Gehörorgan der Fische und Amphibien. Pt. I, 1881.
Stockholm.
*Retzius, G.*, Zur Kenntniss der Morphologie des inneren Ohres bei
Wirbelthieren. Nord. Med. Ark. 1880. Vol. XII, p. 6.
*Retzius, G.*, Ueber die peripherische Endigungsweise der
Gehörnerven. Biol. Untersuch. Stockholm and Leipzig, pp. 51–61.
*Schultze, F. E.*, Zur Kenntniss der Endigungsweise der Hörnerven bei
Fischen und Amphibien. Arch. f. Anat. u. Physiol. 1862, p. 381.
*Stannius, H.*, Handbuch der Zootomie von v. Siebold und Stannius.
Berlin, 1856. 2nd Edit., Pt. II.
*Tafani, A.*, L’organo dell’ udito. Firenze, 1885.
*Waldeyer, W.*, Hörnerv und Schnecke. Stricker’s Handbuch der
Gewebelehre, pp. 915–963.
*Weber, E.*, Amtlicher Bericht über die neunzehnte Versammlung
deutscher Naturforscher und Aerzte in Braunschweig im Sept. 1841.
Printed Braunschweig, 1842.
*Windischmann*, De penitiori auris in amphibiis structura Lipsiae,
1831.
VI. THE EYE.
_a. The cornea and sclerotic._
*Angelucci, A.*, Ueber den Bau u. die Entwickelung des vorderen
Uvealtractus der Vertebraten. Centralbl. f. d. med. Wiss. 1879.
No. 24, p. 417.
*Altmann, R.*, Ueber die Verwerthbarkeit der Corrosion in der
mikroskopischen Anatomie. Arch. f. mik. Anat. 1879. Vol. XVI,
p. 471 (Corneal corpuscles).
*Arnold, J.*, Die Vorgänge bei der Regeneration epithelialer Gebilde.
Virchow’s Arch. 1869. Vol. XLVI, p. 168.
*Arnold, J.*, Experimentale Untersuchungen über die Entwicklung der
Blutcapillaren. Virchow’s Arch. 1871. Vol. LIII, p. 70. 1872.
Vol. LIV, p. 1.
*Boddaert*, Zur Histologie der Cornea. Centralbl. f. med. Wiss. 1871,
p. 337.
*Ciaccio, J. V.*, On the nerves of the cornea and of their
distribution in the corneal tissue of man and animals. Trans.
Micros. Soc. London, 1863. Vol. XI, p. 77.
*Clasow, E.*, Om corneal epithel. Upsala läkareförenings
förhandlingar. 1869. Vol. IV, p. 411.
*Cohnheim, J.*, Ueber die Endigung der sensiblen Nerven in der
Hornhaut. Virchow’s Arch. 1867. Vol. XXXVIII, p. 343.
*Durante, F.*, Sulla terminazione dei nervi della cornea. Richerche
fatte nel laborat. di anat. normal. Roma, pubbl. dal dott. F.
Tocharo. 1873, pp. 81–87.
*Engelmann, T. V.*, Ueber die Hornhaut des Auges. Leipzig, 1867.
*v. Ewetsky*, Ueber das Endothel der Membrana Descemeti. Untersuch.
aus d. pathol. Institut. Zürich, 1875. Vol. III.
*Frey, H.*, Handbuch der Histologie und Histochemie.
*Generisch*, Zur Lehre von den Saftkanälchen in der Cornea. Med.
Jahrb. der Gesellsch. d. Aerzte in Wien. 1871, p. 1.
*Guye, A. G.*, Over bekercellen en in het byzonder over de
bekercellen in de membrana nictitans van den Kïkvonch. Nederl.
Tydschrift v. Gewesh. 1868. Vol. II, p. 135.
*Hansen, A.*, Untersuchungen über die entzündlichen Veränderungen der
Hornhautkörper. Wiener Med. Jahrb. 1871, p. 210.
*Harpeck, C.*, Ueber die Bedeutung der nach Silberimprägnation
auftretenden weissen lücken- und spaltähnlichen Figuren in der
Cornea. Arch. f. Anat. u. Physiol. 1864, p. 222.
*Hartmann, R.*, Ueber die durch den Gebrauch der Höllensteinlösung
künstlich dargestellten Lymphgefässanhänge, Saftcanälchen und
epithelähnlichen Bildungen. Arch. f. Anat. u. Physiol. 1864,
p. 235.
*Heiberg, H.*, Ueber die Neubildung des Hornhaut-Epithels. Wiener
Med. Jahrb. 1871.
*Heisrath, F.*, Ueber d. Zusammenhang d. vordern Augenkammer mit d.
vord. Ciliarvenen. Arch. f. mik. Anat. 1878. Vol. XV, p. 209.
*Helfreich*, Ueber die Nerven der Conjunctiva und Sclera. Würzburg,
1870.
*Henle, J.*, Handbuch der systematischen Anatomie, 1866. Vol. II.
*His, W.*, Untersuchungen über der Bau der Hornhaut, in Verhandlungen
der phys.-med. Gesellschaft in Würzburg. 1856. Vol. IV, p. 90.
*His, W.*, Ueber die Einwirkung des salpetersauren Silberoxydes auf
die Hornhaut. Schweizerische Zeitsch. f. Heilkunde. 1864. Vol. II,
p. 1.
*Hoffmann, F. A.*, Ueber Contractilitätsvorgänge im vorderen Epithel
der Froschhornhaut. Diss. Berlin, 1868.
*Hoffmann, F. A.*, Epithelneubildung auf der Cornea. Virchow’s Arch.
1870. Vol. LI, P. 373.
*Hosch, F.*, Ueber die angebliche Contractilität der Knorpelzellen
und Hornhaut-körperchen. Pflüger’s Arch. f. d. ges. Physiol. 1873.
Vol. VII, p. 515.
*Hoyer, H.*, Ueber den Austritt von Nervenfasern in das Epithel der
Hornhaut. Arch. f. Anat. u. Physiol. 1866, pp. 180–195.
*Hoyer, H.*, Ueber die Nerven der Hornhaut. Arch. f. mik. Anat. 1873.
Vol. IX, p. 220.
*Klebs, E.*, Das Epithel der hintern Hornhautfläche. Centralbl. f. d.
med. Wiss. 1864, p. 513.
*Klein, E.*, Some remarks on the finer nerves of the cornea. Monthly
Journ. Micros. Sci. 1872. Vol. VII, pp. 156–164.
*Klein, E.*, Beiträge zur Kenntniss der peripherischen Verzweigung
markloser Nervenfasern. Centralbl. f. d. med. Wiss. 1871, p. 594.
*Klemensiewicz, R.*, Karyokinese in den fixen Hornhautzellen bei
Entzündung. Centralbl. f. d. med. Wiss. 1884, p. 163.
*v. Kölliker, A.*, Ueber die Nerven der Hornhaut. Mittheilungen der
naturforschenden Gesellschaft in Zürich. 1849.
*v. Kölliker, A.*, Ueber die Nervenendigungen in der Hornhaut. Würzb.
naturw. Zeitschr. 1866. Vol. VI, p. 121.
*Königstein, L.*, Histologische Notizen. Arch. f. Ophthalmologie.
1881. Vol. XXVII, p. 56.
*Königstein, L.*, Beobachtungen über die Nerven der Cornea und ihre
Gefässe. Wiener Sitzungsber. 1877. Vol. LXXVI, Pt. III, p. 17.
*Königstein, L.*, Beobachtungen über die Nerven der Cornea und ihre
Gefässe. Wiener Sitzungsber. 1877. Vol. LXXVI, Pt. III, p. 37.
*Krause, W.*, Ueber das vordere Epithel der Cornea. Göttinger
Nachrichten, 1870. Arch. f. Anat. u. Physiol. 1870.
*Krause, W.*, Anatomischer Jahresbericht für 1871 in Prager
Vierteljahrsschrift.
*Kühne, W.*, Untersuchungen über Protoplasma und die Contractilität.
1864.
*Lavdowsky, M.*, Das Saugadersystem und die Nerven der Cornea. Arch.
f. mik. Anat. 1872. Vol. VIII, p. 538.
*Leber, T.*, Zur Kenntniss der Imprägnationsmethoden der Hornhaut und
ähnlicher Gewebe. Arch. f. Ophthalmologie. 1867. Vol. XIV, p. 300.
*Leydig, F.*, Lehrbuch der Histologie. 1857.
*Lightbody, W. H.*, Observations on the comparative anatomy of the
cornea of vertebrates. Journ. of Anat. and Phys. 1867. Vol. I,
p. 15.
*Lipmann, H.*, Ueber die Endigung der Nerven im eigentlichen Gewebe
und im hinteren Epithel der Hornhaut des Frosches. Virchow’s Arch.
1869. Vol. XLVIII, p. 218.
*Lott, G.*, Ueber den feineren Bau und die physiologische
Regeneration der Epithelien, insbesondere des Cornea-Epithels.
Centralbl. f. d. med. Wiss. 1871.
*Moseley, H. N.*, Some remarks on the nerves of the cornea of the
rabbit and frog. Quart. Journ. Micros. Sci. 1871. Vol. XI, p. 261.
*Müller, C. F.*, Histologische Untersuchungen über die Cornea.
Virchow’s Arch. 1867. Vol. XLI, p. 110.
*v. Recklinghausen, F.*, Notiz über Silberimprägnation. Virchow’s
Arch. 1860. Vol. XIX, p. 451.
*v. Recklinghausen, F.*, Die Lymphgefässe und ihre Bedeutung zum
Bindegewebe. Berlin, 1862.
*Robinski*, Die Kittsubstanz auf Reaction des Argentum nitricum.
Arch. f. Anat. u. Physiol. 1871, p. 184.
*Rollett, A.*, Ueber das Gefüge der Substantia propria corneae.
Sitzungsb. Wiener Akad. 1859. Vol. XXXIII, p. 516.
*Rollett, A.*, Ueber die Contractilität der Hornhautkörper und die
Hornhauthöhlen. Centralbl. f. d. med. Wiss. 1871, p. 193.
*Rollett, A.*, Ueber die Hornhaut. Stricker’s Gewebelehre. 1872,
p. 1091.
*Saemisch, T.*, Beiträge zur normalen und pathologischen Anatomie des
Auges (Nerves of Cornea). Leipzig, 1862.
*Sattler, E. E.*, Die Verwendung des Lapisstiftes sur Untersuchung
der Epithelien. Arch. f. mik. Anat. 1882. Vol. XXI, p. 672.
*Schalygen, C.*, Ueber Hornhautepithel und besonders über Vermehrung
der Zellen desselben. Arch. f. Ophthalmol. 1866. Vol. XII, p. 83.
*Schneider, A.*, Ueber die Vermehrung der Epithelzellen der Hornhaut.
Würzb. naturw. Zeitsch. 1862. Vol. III, p. 105.
*Schwalbe, G.*, Ueber ein mit Endothel bekleidetes Höhlensystem
zwischen Choroidea und Sclerotica. Central. f. d. med. Wiss.
Berlin, 1868. No. 54.
*Schweigger*, Ueber den Bau der Hornhaut. Allg. med. Centralzeitung.
Berlin, 1862. No. 4.
*Schweigger-Seidel, F.*, Ueber die Grundsubstanz und die Zellen der
Hornhaut des Auges. Berichte d. math.-physik. Classe der Königl.
Sächs. Gesellsch. d. Wissenschaft. 1869. Vol. XXI, pp. 305–359.
*Stricker, S.*, Conjunctiva und Sclerotica im Handb. der Lehre von
den Geweben des Menschen und der Thiere. 1872, p. 1142.
*Swaen, M. A.*, Des éléments cellulaires et des canaux plastiques
dans la cornée de la grenouille. Bulletin de l’Acad. roy. de
Belgique. 1876. 2nd Series, Vol. XLII, pp. 144–183.
*Tamamscheff, T.*, Ueber die Membrana Demoursiana. Centralbl. f. d.
med. Wiss. Berlin, 1869.
*Waldeyer, W.*, Microscopische Anatomie der Cornea, Sclera, Lider und
Conjunctiva, in Handbuch der gesammten Augenheilkunde. 1874.
*Wolff, W.*, Die Nerven der Cornea. Arch. f. mik. Anat. 1882.
Vol. XX, p. 373.
*Zielonko, J.*, Ueber die Entwicklung und Proliferation von
Epithelien und Endothelien. Arch. f. mik. Anat. 1874. Vol. X,
p. 351.
_b. The lens, choroid, iris, appendages, anterior and posterior
chambers._
*Altmann, R.*, Ueber Corrosion in der Histologie. Centralbl. f. d.
med. Wiss. 1878, p. 245.
*Altmann, R.*, Ueber die Verwerthbarkeit der Corrosion in der
mikroskopischen Anatomie. Arch. f. mik. Anat. 1879. Vol. XVI,
p. 471 (Blood-vessels of the choroid).
*Angelucci, A.*, Ueber den Bau und die Entwickelung des vorderen
Uveatractus der Vertebraten. Centralbl. f. d. med. Wiss. 1879,
p. 417.
*Arnold*, Die Linse. Handbuch der gesammten Augenheilkunde. 1874.
*Barkau, A.*, Beiträge zur Entwicklungsgeschichte des Auges der
Batrachier. Wiener Sitzungsber. 1866. Vol. LIV, Pt. I, pp. 70–75.
*Becker*, Untersuchungen über den Bau der Linse bei dem Menschen und
den Wirbelthieren. Arch. f. Ophthalmologie. 1863. Vol. IX, Pt. II,
pp. 1–42.
*Biedermann, W.*, Zur Histologie und Physiologie der Schleimsekretion
(Membrana nictitans). Wiener Sitzungsber. 1886. Vol. XCIV.
*Born, G.*, Ueber die Nasenhöhlen und den Thränennasengang der
Amphibien. Morph. Jahrb. 1875. Vol. II, p. 4.
*Bubuchin*, Die Linse. In Stricker’s Handb. der Gewebelehre. 1872.
*Burow*, De vasis sanguif. ran. Diss. Regiomonti, 1838.
*Ciaccio, C. V.*, Beobachtungen über den inneren Bau des Glaskörpers
im Auge des Menschen und der Wirbelthiere im Allgemeinen.
Moleschott’s Untersuchungen. 1870. Vol. X, p. 385.
*Faber, C.*, Der Bau der Iris des Menschen und der Wirbelthiere.
Leipzig, 1876.
*Frey*, Handbuch der Histologie und Histochemie des Menschen. 1874.
*Fubini, S.*, Beiträge zum Studium der Krystalllinse. Moleschott’s
Untersuchungen. 1876. Vol. XI, p. 291.
*Golubew*, Beiträge zur Kenntniss des Baues und der
Entwicklungsgeschichte der Capillargefässe des Frosches. Arch. f.
mik. Anat. 1869. Vol. V, p. 49.
*Grünhagen*, Ueber das Vorkommen eines Dilatator pupillae in der
Iris. Zeitsch. f. rat. Med. Vol. XXVIII, pp. 178, 186.
*Heisrath, F.*, Ueber den Zusammenhang der vorderen Augenkammer mit
den vorderen Ciliarvenen. Arch. f. mik. Anat. 1878. Vol. XV,
p. 209.
*Henle, J.*, Zur Anatomie der Crystalllinse. Abhandl. Gesells. d.
Wiss. zu Göttingen. 1878. Vol. XXIII.
*Henle, J.*, Zur Entwicklungsgeschichte der Krystalllinse und zur
Theilung des Zellkerns. Arch. f. mik. Anat. 1882. Vol. XX, p. 413.
*Hirschberg*, Zur Dioptric und Ophthalmologie der Amphibienaugen.
Arch. f. Anat. u. Physiol. 1887, p. 493.
*Iwanoff*, Beiträge zur normalen und pathologischen Anatomie des
Froschglaskorpers. Centralbl. f. d. med. Wiss. 1868, p. 129.
*Klein, E.*, On the peripheral distribution of non-medullated
nerve-fibres (Nerves of the nictitating membrane). Quart. Journ.
Micros. Sci. 1872. Vol. XII, pp. 21–32.
*Koganeï, J.*, Untersuchungen über den Bau der Iris des Menschen und
der Wirbelthiere. Arch. f. mik. Anat. 1885. Vol. XXV, p. 1.
*Koganeï, J.*, Untersuchungen über den Bau der Iris. Sitzungsber. d.
Acad. d. Wiss. Berlin, 1885, p. 105.
*v. Kölliker, A.*, Handbuch der Gewebelehre. 1867.
*Langer, C.*, Ueber das Lymphgefässsystem des Frosches. Wiener Acad.
Sitzungsb. 1867. Vol. LV, Pt. I, p. 603.
*Leydig, F.*, Anatomisch-histologische Untersuchungen über Fische und
Reptilien, 1853.
*Leydig, F.*, Lehrbuch der Histologie des Menschen und der Thiere.
1857.
*Manz, W.*, Ueber den Mechanismus der Nickhautbewegung beim Frosche.
Berichte über d. Verhandl. d. naturforsch. Gesell. Freiburg, 1862.
Vol. II, p. 391.
*Moriggia, A.*, Ueber die beste Darstellungsweise und die Entwicklung
der Röhrchen der Krystalllinse. Moleschott’s Untersuchungen. 1870.
Vol. X, p. 658.
*Openchowski, T.*, Histologisches zur Innervation der Drüsen.
Pflüger’s Arch. f. d. ges. Physiol. 1882. Vol. XXVII, pp. 223–232.
*Petit*, Sur l’œil de la grenouille. Mém. de l’académie d. Sciences,
1737; see also Lehrbuch d. vergleich. Anatomie, Stannius, Berlin,
1846, p. 198.
*Robinski, S.*, Zur Anatomie, Physiologie und Pathologie der
Augenlinse des Menschen und der Wirbelthiere. Arch. f. Anat. u.
Physiol. 1872, p. 178.
*Robinsky, S.*, Die Augenlinsensterne des Menschen und der
Wirbelthiere. Centralbl. f. d. med. Wiss. 1877, p. 51.
*Sattler, E. E.*, Die Verwendung des Lapisstiftes zu Untersuchungen
der Epithelien. Arch. f. mik. Anat. 1882. Vol. XXI, p. 672.
*Stricker, S.*, Untersuchungen über die capillaren Blutgefässe in
der Nickhaut des Frosches. Wiener Sitzungsb. 1865, Vol. LI,
Pt. II, pp. 16–27; and Moleschott’s Untersuchungen, 1866, Vol. X,
pp. 168–180.
*Stricker, S.*, Untersuchungen über die mechan. Leistungen d.
acirrösen Drüsen. Wiener med. Jahrb. 1880, p. 355; also
Wiener Sitzungsb. 1880 (Membrana nictitans and skin); also in
Moleschott’s Untersuchungen. 1870. Vol. X, p. 237.
*Stricker, S.*, Studien über den Bau und das Leben der capillaren
Blutgefässe. Wiener Sitzungsb. 1866. Vol. LII, Pt. II, p. 379.
*Stricker, S.*, Untersuchungen über die capillaren Blutgefässe in der
Nickhaut des Frosches. Moleschott’s Untersuchungen. 1870. Vol. X,
p. 168.
*Thin, G.*, Contribution to the anatomy of the lens. Journ. of Anat.
and Physiol. 1876. Vol. X, p. 223.
*Valentin*, Handbuch der Physiologie v. Wagner. 1842.
*Virchow, H.*, Ueber die Gefässe im Auge und in der Umgebung des
Auges beim Frosche. Zeit. f. wiss. Zool. 1881. Vol. XXXV,
pp. 247–281.
*Virchow, H.*, Ueber die Gefässe des Kopfes und des Auges des
Frosches. Verhandl. Würzburg. 1881. Vol. XV, p. xxxiv.
*Virchow, H.*, Mittheilungen zur vergleichenden Anatomie des
Wirbelthierauges. Versamml. deutsch. Naturf. und Aerzte.
Strassburg. 1885, pp. 409, 410.
*Virchow, H.*, Ueber den ciliaren Muskel des Frosches. Verhandl. d.
physiol. Gesell. zu Berlin. 1885, p. 571.
*Virchow, H.*, Ueber die verschiedenen Formen des Ligamentum
pectinatum iridis. Versamml. d. Naturf. und Aerzte. 1885, p. 409.
*Zimmermann, W.*, Ueber circumvasale Safträume der Glaskörpergefässe
von Rana esculenta. Arch. f. mik. Anat. 1886. Vol. XXVII, p. 410.
_c. The retina._
*Babuchin*, Vergleichende histologische Studien. Würzburger
naturwissensch. Zeitsch. 1864. Vol. V, p. 127.
*Beauregard, M. H.*, Contribution à l’étude du rouge rétinien. Journ.
de l’anat. et de la physiol. 1879. Vol. XV, p. 161.
*Boll, F.*, Zur Anatomie und Physiologie der Retina. Berlin. Acad.
Monatsber. 1876, p. 783.
*Dennissenko, G.*, Vorläufige Bemerkungen zur Lehre über den Bau
der Netzhaut. Mitt. aus dem embryolog. Institut. d. Wiener
Universität, 1880, Vol. II, p. 1; Abstract in Centralbl. f. d.
med. Wiss. 1880, P. 739.
*Dennissenko, G.*, Ueber den Bau der äusseren Körnerschicht der
Netzhaut bei den Wirbelthieren. Arch. f. mik. Anat. 1881.
Vol. XIX, p. 395.
*Dietl, M. J.*, Beitrag zur Kenntniss des feineren Baues der
Stäbchenaussenglieder in der Netzhaut des Frosches. Arch. f.
Augen- u. Ohrenheilkunde. 1878. Vol. VII, pp. 17–24.
*Dobrowolsky*, Die Doppelzapfen. Arch. f. Anat. u. Physiol. 1871.
*Dobrowolsky*, Zur Anatomie der Retina. Arch. f. Anat. u. Physiol.
1871.
*Ewart, J. C.*, Notes on the minute structure of the retina and
vitreous humour. Journ. of Anat. and Physiol. 1875. Vol. IX.
*Ewart, J. C.*, and *Thin, G.*, On the structure of the retina.
Journ. of Anat. and Physiol. 1876. Vol. IX, p. 166.
*Frisch*, Gestalten des Choroidalpigments. Wiener Sitzungsber. 1868.
Vol. LVIII, pp. 316–320.
*Heinemann, C.*, Beiträge zur Anatomie der Retina. Arch. f. mik.
Anat. 1877. Vol. XIV, p. 409.
*Helfreich*, Ophthalmoscopische Mittheilungen über den Purpur der
Retina. Centralbl. f. d. med. Wiss. 1877, p. 113.
*Henle* and *Merkel*, Ueber die sogenannte Bindesubstanz der
Centralorgane des Nervensystems. Zeitsch. f. rat. Med. 3rd Series,
1869. Vol. XXXIV.
*Hensen*, Ueber das Sehen in der Fovea centralis. Virchow’s Arch.
1867. Vol. XXXIX, p. 75.
*Hoffmann*, Lehrbuch der Anatomie der Sinnesorgane.
*Hoffmann*, Bronn’s Thierbuch. Leipzig and Heidelberg, 1873–1878.
Vol. VI, pp. 274–297.
*Hulke, J. W.*, A contribution to the anatomy of the amphibian and
reptilian retina. Quart. Journ. Micros. Sci. 1864, Vol. IV,
p. 236; and London Ophthalmic Hospital Reports, 1864.
*Hulke, J. W.*, On the retina of amphibia and reptiles. Journ. of
Anat. and Physiol. 1867. Vol. I, p. 94.
*Kühne, W.*, Ueber den Sehpurpur. Centralbl. f. d. med. Wiss. 1877,
p. 193.
*Kühne, W.*, Fortgesetzte Untersuchungen über die Retina und die
Pigmente des Auges. Heidelberger physiol. Untersuch. 1878,
Vol. II, p. 89; Abstract in Centralbl. f. d. med. Wiss. 1879,
p. 276.
*v. Kölliker, A.*, Zur Anatomie und Physiologie der Retina. Verhandl.
d. phys.-med. Gesellsch. Würzburg, 1852. Vol. III, p. 316.
*v. Kölliker, A.*, Microscopische Anatomie. 1854. Vol. II.
*v. Kölliker, A.*, Handbuch der Gewebelehre. 1867.
*Krause, W.*, Die Nervenendigung in der Retina. Arch. f. mik. Anat.
1876. Vol. XII, pp. 742–790.
*Krause, W.*, Die Nervenendigung innerhalb der terminalen Körperchen.
Arch. f. mik. Anat. 1881. Vol. XIX, p. 53.
*Landolt*, Beitrag zur Anatomie der Retina vom Frosch, Salamander und
Triton. Arch. f. mik. Anat. 1871. Vol. VII, p. 81.
*Leydig, F.*, Anatomisch-histologische Untersuchungen über Fische und
Reptilien. 1853.
*Leydig, F.*, Die Farbe der Retina und das Leuchten der Augen. Arch.
f. Naturgesch. 1877. Vol. XXXIII, p. 8.
*Manz, W.*, Ueber den Bau der Retina des Frosches. Zeitsch. f. rat.
Med. 3rd Series, 1861. Vol. X, pp. 301–322.
*Manz, W.*, Die Ganglienzellen der Froschnetzhaut. Zeitsch. f. rat.
Med. 3rd Series, 1866. Vol. XXVIII.
*Merkel*, Zur Kenntniss der Stäbchenschicht der Retina. Arch. f.
Anat. u. Physiol. 1870, p. 642.
*Morano, F.*, Die Pigmentschicht der Retina. Arch. f. mik. Anat.
1872. Vol. VIII, p. 81.
*Morano, F.*, Stomata in der Pigmentschicht der Retina. Centralbl. f.
d. med. Wiss. 1875, p. 67.
*Müller, H.*, Histologie der Netzhaut. Zeitsch. f. wiss. Zool.
1851–52. Vol. III, p. 234.
*Müller, H.*, Ueber sternförmige Zellen der Retina. Würzb. Verhandl.
1852. Vol. II, pp. 216–218.
*Müller, H.*, Ueber einige Verhältnisse der Netzhaut bei Menschen und
Thieren. Würzb. Verhandl. 1853. Vol. IV, p. 96.
*Müller, H.*, and Kölliker, A., Retina-Tafel. Plate XIX in Ecker’s
Icones Physiol. Leipzig, 1854.
*Müller, H.*, Observations sur la structure de la rétine de certains
animaux. Compt. rend. 1856, Vol. XLIII, p. 743; and Annales hist.
nat. 1856, Vol. XVIII, p. 492.
*Müller, H.*, Anatomisch-physiologische Untersuchungen über die
Retina des Menschen und der Wirbelthiere. Zeitsch. f. wiss. Zool.
1857. Vol. VIII, p. 27.
*Müller, W.*, Ueber die Stammentwicklung des Sehorgans der
Wirbelthiere. Leipzig, 1874, Festgabe an Carl Ludwig; Abstract in
Centralbl. f. d. med. Wiss. 1877, pp. 372 and 388.
*Ogneff, J.*, Histogenese der Retina. Centralbl. f. d. med. Wiss.
1881, p. 641.
*Ogneff, J.*, Ueber die moleculäre Schicht und die sogenannte
reticuläre Substanz der Retina. Centralbl. f. d. med. Wiss. 1883,
p. 801.
*Oppenheimer, L. S.*, Die Stäbchen in der Netzhaut der
Froschembryonen. Schenk’s Embryol. Mitt. Wien. 1878, p. 163.
*Ranvier, L.*, Traité technique d’histologie, sixième fasicule. 1882.
*Ritter*, Ueber den Bau der Stäbchen und äusseren Endigungen der
Radialfasern an der Netzhaut des Frosches. Arch. f. Ophthalmol.
1859.
*Ritter*, Zur Histologie des Auges. Arch. f. Ophthalmol. 1868.
Vol. XI.
*Schifferdecker*, Studien zur vergleichenden Histologie der Retina.
Arch. f. mik. Anat. 1886. Vol. XXVIII, p. 305.
*Schultze, M.*, Zur Anatomie und Physiologie der Retina. Arch. f.
mik. Anat. 1866. Vol. II, pp. 175–286.
*Schultze, M.*, Ueber Stäbchen und Zapfen der Retina. Arch. f. mik.
Anat. 1867. Vol. III, p. 215.
*Schultze, M.*, Bemerkungen zu dem Aufsatze des Dr. W. Steinlin.
Arch. f. mik. Anat. 1868. Vol. IV, pp. 10–21.
*Schultze, M.*, Die Retina. Stricker’s Handbuch der Gewebelehre. 1871.
*Schultze, M.*, Ueber die Nervenendigung in der Netzhaut des Auges
bei Menschen und bei Thieren. Arch. f. mik. Anat. 1869. Vol. V,
p. 380.
*Schwalbe*, Lehrbuch der Anatomie der Sinnesorgane. Erlangen, 1885,
p. 392, etc.
*Steinlin, W.*, Zur Anatomie und Physiologie der Retina. Arch. f.
mik. Anat. 1868. Vol. IV, p. 10.
THE SKIN AND THE SENSE-ORGANS.
I. THE SKIN AND ITS APPENDAGES.
The general characters and the colouring of the skin have already
been described (pp. 4 to 7). The skin consists of the _cutis vera_ or
corium, and the cuticle or epidermis, and is possessed of numerous
glands.
*a.* The *epidermis* (Figs. 228, 230) consists of several layers
of epithelial cells, those of the deepest layer being more or less
columnar in form, those of the middle layer shorter and polygonal,
while those of the superficial layer are flattened, very transparent,
and horny.
All the surfaces of these cells are serrated, the serrations being,
however, with difficulty seen on the free surface of the superficial
cells (Leydig). Each cell has a distinct nucleus; in the deeper cells
the nucleus is oval, broad, and rounded, in the superficial cells
flattened and thin.
The surface of the epidermis (Fig. 230) forms a very beautiful
mosaic of flat cells, chiefly hexagonal in form, with pale, central,
oval nuclei. Here and there two adjacent cells appear to enclose a
semilunar space (Fig. 228 _D_); these spaces are occupied by peculiar
cells (goblet-cells, E. Schultze; mucous cells, Leydig), which do not
belong to the superficial cells but the layer of cells immediately
beneath the horny layer (Schultze, Pfitzner). The cells are rounded
or flask-shaped, and closely resemble the epithelial goblet-cells or
chalice-cells. According to Rudneff they open on the free surface by
stomata; this is, however, denied by Schultze and others.
[Illustration: Fig. 228.
Vertical section through the epidermis from the head of _Rana
esculenta_; after F. E. Schultze. Magnified 600 times.
_A_ Horny layer.
_B_ Middle layer.
_C_ Deep layer.
_D_ Isolated mucous-cells.
]
[Illustration: Fig. 229.
Vertical section through the skin of the back; after Wiedersheim.
_Co_ Superficial layer of cutis.
_Co^1_ Middle layer of cutis.
_Co^2_ Deep layer of cutis.
_D_ Cutaneous glands.
_D^1_ Ducts of cutaneous glands.
_Ep_ Epidermis.
_H_ Horny layer of epidermis.
_P_ Pigment-cells.
_W_ Papillae.
]
According to Pfitzner these cells secrete a substance, which has an
important function in connection with the process of casting the skin,
which consists in the separation of the upper layer from that below
brings about a complete shedding of the skin (Wiedersheim).
[Illustration: Fig. 230.
Surface view of epidermis of _Rana temporaria_; after Eberth.
_A_ Epidermal cell.
_B_ Stoma-cell.
_C_ Attached cuticle from duct of gland.
_D_ Protoplasm and nucleus of stoma-cell.
]
[Illustration: Fig. 231.
Nerve terminations in the branched pigment-cells of the cutis; after
Ehrmann. Hartnack, Obj. 8, Oc. 3.
I. Pigment ceasing abruptly at junction of nerve.
II. Pigment gradually ceasing along the nerve.
]
[The horny layer is, for the most part, very thin, as it consists of
one or two layers of flattened cells only (Schultze), but in some
situations, as on the back and especially on the under surface of the
toes, it is much thickened, and is then rough.
Deeply pigmented, branched cells, capable of contractile movements, are
also found, somewhat sparsely distributed, in the epidermis (Leydig, H.
Müller, Schultze).]
*b.* The *cutis* (Fig. 229, _Co_, _Co^1_, _Co^2_). The epidermis is
generally attached to the corium by means of a continuous layer of
branched cells, which is deeply stained when the animals are fed with
madder (Katschenko). Many of these cells are pigmented. This layer is
seldom flat, but is raised into papillae and folds, which are repeated
by the superimposed epidermis. In addition to this layer the corium
has, except in the webs and supplemental toes, three distinct layers of
connective-tissue, together with much unstriped muscle-fibre (Eberth).
The *superficial layer* (Fig. 229 _Co_) is a loosely-meshed, much
pigmented, vascular layer; it forms a loose support for the numerous
glands, and is traversed by numerous nerves.
The *middle layer* (_Co^1_) forms the groundwork of the cutis; it is
much firmer and more compact than the superficial layer; in section
it appears as a broad band, bounded superficially by a sharp line.
It is chiefly composed of closely packed connective-tissue fibres,
which have, for the main part, a horizontal or wavy course; at certain
points, however, vertical fibres are seen passing towards the surface
and hiding the sharp contour (between _Co_ and _Co^1_). At such points
the two sets of fibres form a sort of basket-work arrangement.
The *deepest layer* (Fig. 229 _Co^2_) is composed of very delicate,
white and yellow elastic fibres, and vessels and nerves; it attaches
the whole integument to the underlying organs. By the looseness of its
structure it forms an important lymph-space.
[The *muscle-fibre* of the cutis is very unevenly distributed. It is
found somewhat freely in the region of the back, the dorsal surface
of the head, and the neck; less freely on the dorsal surfaces of the
extremities, very sparsely on the abdomen, breast, and ventral surfaces
of the extremities; in the feet it appears to be absent (Eberth).
The *pigment* of the skin. As already mentioned pigmented cells occur
in the epidermis, but by far the greater quantity of the cutaneous
pigment is found in the cutis, and more especially in the loose layer
of branched cells, which form the boundary between epidermis and true
cutis. These cells, known as chromatophore-cells, have been carefully
investigated by Harless. They play an extremely important part in
bringing about the well-known changes in the colouring of the skin.
Bimmerman has proved that these cells are influenced by stimulation of
the nerves supplying the region in which they occur. Ehrmann has been
able to trace a direct connection between the nerve-fibres and the
pigment-cells (Fig. 231 I, II). In such cases the pigment was sometimes
sharply marked off, at others was gradually lost along the nerve.]
*c.* The *papillae* and *ridges* of the skin are classified by Leydig
as follows: (1) Small ridges, (2) larger ridges, (3) papillae with
touch-bodies, (4) papillae without touch-bodies, (5) papillae with the
ducts of glands, (6) capillaries in the form of papillae, (7) small
elevations, including the lateral organs.
[All these structures are derived from the cutis, the epithelium above
simply repeating the elevation, and being itself either not increased
in thickness or only to a slight degree. (For further description of
some of these papillae, see Organs of Tactile Sensation, p. 380.)
Peculiar wart-like papillae are found on the articulations of the first
phalanges with the metatarsus, on the same articulations and on the
articulations between the first and second phalanges of the third and
fifth toes, and on the articulations between the first, second, and
third phalanges of the fourth toe. These papillae are connected with
the long flexor tendons by fine tendinous bands (Klein).
*Temporary papillae* are developed in the females of _Rana
temporaria_ during the breeding season; according to O. Huber (_l.
c._), who has described them, their distribution and structure is as
follows:--
During the breeding season the skin of the sides of the trunk of
female specimens of _Rana temporaria_ is rough; the small elevations,
to which this roughness is due, are each about the size of the head
of a pin, and have the appearance of small, rounded, white or pale
rose-coloured, warty growths. The papillae reach their greatest
development and are most numerous on the sides of the trunk (Fig. 232
I); they may be traced on to the tympanic membrane, where they are
arranged in a ring, and in some cases under the eyes to the sides of
the snout.
Anteriorly the papillae are absent from the median portion of the
dorsal surface of the trunk, but posteriorly, behind a line joining
the anterior extremities of the two iliac bones, the papillae cover
the whole surface.
The papillae are large and very numerous around the arms, and pass
by gradual, transitionary stages into the ordinary papillae of the
region. Further they may be traced backwards along the anterior or
extensor surface of the thigh, the upper surface of the leg, foot,
and fifth toe. Occasionally a few papillae were found on flexor
surfaces of the third and fourth metatarsus, and very rarely were any
discovered on the fore-limbs. They occur in no other batrachian of
Germany (Huber).
[Illustration: Fig. 232.
I. Diagram to show the distribution of the temporary papillae in
_Rana temporaria_; after Huber.
II, III. Vertical sections through a temporary papilla; after Huber.
]
Each papilla (Fig. 232 II and III) consists of a hemispherical
elevation of the cutis, and is covered either by a layer of normal
epidermis or in some very rare cases the epidermis was slightly
thickened. The papilla consists of a firm connective-tissue stroma,
and is from 0.2–0.4 mm. in height, 0.4–0.5 mm. broad (after hardening
in alcohol). Such glands as exist in the papilla usually open
laterally (Fig. 232 III), and the blood-vessels are numerous.
The epidermis covering the papilla is well supplied with
nerve-fibres, derived from large ganglion-cells in the papilla
(Fig. 232 III). The branched pigment-cells, so numerous in the
rest of the skin, are absent from the upper parts of the papillae
(Fig. 232 II); the pigment-cells may cease either abruptly or
gradually.
The rose-colour of the papillae is due to the presence of a golden
red pigment. After the breeding season the papillae are gradually
lost, and the pigment-cells wander into the unoccupied parts.
Huber compares the arrangement of the nerves to that of the
‘touch-spots’ of Merkel.
d. The *glands* of the skin are of two kinds, serous and mucous; they
have been fully described by Engelmann and Openchowski.
(1) The *serous glands* (Körnerdrüsen, Engelmann) are large, averaging
in diameter 0.2–0.4 mm., but others vary in size from 0.13–0.8 mm.
in diameter. They are found chiefly on the dorsum of the trunk and
arranged in groups, which vary in dimensions from 3–20 mm. in length
and 2–4 mm. in breadth. They may be found in any part between the
ear-region and the anus, on the dorsal surface of the thigh, especially
towards the outer and inner borders. They are found very sparsely
distributed on the ventral surface of the trunk and on other parts of
the extremities, though as a rule a few are found on the dorsal surface
of the feet and near the phalanges. They are wanting in the nictitating
membrane.
The glands have a rounded form, with the ducts placed at their
superficial poles. The glands possess three coats; externally is a
coat of connective-tissue, the fibres of which are arranged closely
together, and cross one another at acute angles: these fibres are
continuous with the connective-tissue of the surrounding cutis. Inside
this coat is a thick layer of muscle-fibre (0.005–0.015 mm.); the
muscle-cells are arranged meridionally, with the one pole towards the
superficial surface of the gland, the other pole at the deep surface
(Hensche). Many of the fibres, however, extend only one-fourth or
one-third of this distance.
The innermost coat is a simple layer of epithelial cells, which rests
directly on the muscle-layer; no basement-membrane or space of any
kind having been discovered between the two layers. When examined in
the recent state these cells are conical or cylindrical in shape,
and have the appearance of goblet-cells: they possess a delicate but
distinct cell-wall, but are open towards the lumen of the gland. One or
sometimes two rounded nuclei are found towards the base of the gland,
and surrounded by a small amount of granular protoplasm; the rest of
the cell is occupied by a mass of small, rounded, highly refractive
granules of about 0.002–0.01 mm. in diameter. These granules are also
to be found in the protoplasm of the cell; they contain a substance
capable of swelling freely, and present many points of resemblance to
the granules found in the cells of the oviducts.
These glands represent the poison-glands or lateral glands of toads,
and the ear-glands or parotids of Caecilia (Leydig). According to
Leroux[81], Gratiolet and Cloëz[82], the reaction of these glands in
toads varies; according to du Bois-Reymond[83] the reaction is, in
frogs, acid; Engelmann[84] found the reaction of these glands, in
frogs, to be neutral, frequently, however, with a tendency to either
acidity or alkalinity.
These glands correspond with the ‘large glands’ of Hensche, the
‘contractile glands’ of Stieda, the ‘large, dark glands’ of Eberth,
and the ‘large contractile glands’ of Leydig’s earlier publications.
[Footnote 81: Journal de Médicine, Vol. XI, p. 75.]
[Footnote 82: Comptes rendus, 1851, Vol. XXXII, p. 582.]
[Footnote 83: Untersuchungen über thier. Electricität, 1830, Vol. I,
p. 17.]
[Footnote 84: Arch. f. d. ges. Physiol., 1852, Vol. V, p. 505.]
(2) The *mucous glands* are, as a rule, smaller, more numerous, and
more evenly distributed than the serous glands. Usually they lie in
such close proximity as almost to touch one another; according to
Engelmann an average number of sixty is found in one square millimeter;
on the abdomen 62–68; flexor surfaces of the posterior extremities in
some places 76, but in others only 30–40; on the webs only 2–6 to the
square millimeter. On the nictitating membrane they are arranged in two
or three parallel rows, are large, and closely applied to each other.
They are wanting on the deeper surface of the nictitating membrane.
The glands are generally rounded in form and have a short neck
(Fig. 229). Glands in the recent condition, and not fully contracted,
have a diameter of 0.06–0.21 mm., the majority measure 0.12–0.16 mm.
in diameter. The upper pole of the gland is usually placed directly
under the boundary between epidermis and cutis, and, as a rule, about
0.06–0.1 mm. beneath the superficial surface of the skin. The duct
usually passes directly to the surface, in a straight line.
The structure of the glands corresponds, in general, with that of the
serous glands. Externally is a coat of connective-tissue, which is,
however, more firmly attached to the muscular coat than in the case
of the serous glands, and may easily be mistaken for a structureless
basement-membrane[85] (Eberth). The muscular coat is very thin, and
consists of 16–20 flat, spindle-shaped fibres; extending from the
upper to the lower pole as in the serous glands. At a short distance
(0.015–0.022 mm.) from the upper or superficial pole each fibre has an
ellipsoid thickening, composed of granular protoplasm, and containing a
clear oval nucleus.
[Footnote 85: Openchowski (_l. c._) describes a basement-membrane.]
The inner coat is composed of a single layer of epithelium, placed
directly on the muscular coat. The epithelium has a thickness of about
0.01–0.02 mm.; it is, however, usually thicker towards the base than
towards the duct. The boundaries between the cells are very indistinct,
and so give the epithelium the appearance of a continuous layer of
protoplasm. The glandular epithelium is not directly continuous with
the epithelium of the duct.
The shape of the cells depends upon their physiological condition.
In a state of semi-contraction of the gland, the cells are cubical,
and their free borders pushed into the lumen in a slight convexity;
when the gland is fully distended the cells are two or three times as
broad as deep; in a fully contracted gland the cells are conical or
cylindrical. In the first-mentioned condition their diameter varies
from 0.006–0.018 mm. The larger glands are estimated to possess about
150 cells, the smaller only thirty to forty (Engelmann).
The cells appear to have no cell-wall, certainly they possess none
on their free surfaces. Their protoplasm distends very freely on the
addition of water. As a rule some cells are much more granular than
others of the same gland; each cell has a rounded oval, clear nucleus,
and vacuoles are frequently met with.
The lumen of the gland contains a colourless, transparent, watery
fluid, which contains mucous material.
The ducts of the glands are thick-walled cylinders, circular in
section. Their diameter varies from 0.02–0.05 mm., their length is
equal to the depth of the superimposed epidermis. The wall of the duct
is lined with two or three concentric layers of highly refractive,
nucleated cells. The cells are arranged parallel to the length of the
duct: in transverse section they are sickle-shaped or semilunar. In
the upper third or fourth of the duct the inner wall is lined with
a cuticle, very resistant to the action of acids or alkalies: it is
thrown off with the skin in the process of casting. In the horny layer
of the epidermis this cuticle is partially closed by a stoma-cell
(Eberth), (Fig. 230), which possesses a tri-radiate opening.
The glands correspond with the ‘non-contractile glands’ of Hensche,
the ‘dark and bright glands’ of Stieda, the ‘glandule mezzane,
piccole e piccolissime (ad epitelio pavimentoso)’ of Ciaccio, and the
‘small, dark, and medium-sized, bright glands’ of Eberth.
*e.* The *peculiarities* of the *skin* of the *supplemental toe* and
*webs*. The supplemental toe presents, in the male, a rounded, oval
swelling (Fig. 234 I, _D_), with the end of the digit projecting from
the distal end.
Normally this swelling is usually of a grey colour; during the breeding
season, however, the swelling enlarges, and becomes of a black or deep
brown colour (Leydig).
[Illustration: Fig. 233.
Vertical section through the epidermis of the supplemental toe of _Rana
esculenta_; after E. Schultze. Magnified 400 times.
]
The epidermis covering this swelling (Fig. 233) is much thickened
and produced into projecting papillae. The cutis also shows a marked
thickening and an increase in vascularity; the glands are of the kind
described as mucous glands (Engelmann). They present, however, an
immense increase in size, and at the same time are so closely applied
to one another as to form the main part of the enlargement (see also
Organs of Tactile Sensation).
[Illustration: Fig. 234.
I.
Fore-foot of a male frog.
_D_ Glandular swelling on the supplemental toe.
_W_ Warty papillae on the inter-phalangeal joints.
II.
Vertical section through the swelling on the supplemental toe of a male
frog.
_B_ Blood-vessels.
_Co_ Cutis.
_D_ Glands.
_Ep_ Epidermis.
_M_ Muscles.
_P_ Pigment-cells.
]
In the *webs* the various layers of the corium are more or less fused
together, and cannot be distinguished from each other; the glands are,
as a rule, smaller than on the general surface of the skin.
*f.* The *blood-vessels* and *lymphatics* of the skin.
(1) The *blood-vessels* of the skin are arranged in two networks; the
one is situated immediately beneath the epidermis, and consists of fine
capillaries, forming a fine-meshed network, which enclose the ducts of
the glands. The meshes vary considerably in size and shape (Hyrtl and
Langer). The second network of vessels is situated under the cutis; the
vessels forming it are small, and the meshes formed are large. From
this network vertical branches pass to form the superficial network;
these branches usually course along the strands of vertical fibres
already described, and break up to form capillaries only when they
reach the deeper surface of the epidermis (Langer), (Fig. 235 I).
[Illustration: Fig. 235.
The blood-vessels and lymphatics of the skin; after Langer. Arteries
striped, lymphatics shaded.
I. Vertical section through skin of thigh.
II. Horizontal view of arteries and lymphatics of the skin.
III. Peculiar tortuous arteries of the lamina inguinalis.
IV. Arteries and lymphatics of the web.
]
In _some situations_, however, the vertical branches divide earlier;
this is especially the case in parts where the glands are very closely
packed, as in the nictitating membrane, the upper lip, and the
swelling of the supplemental toe (in the male). In these parts the
division takes place at the deeper surface of the glands (Langer).
A _peculiar arrangement_ of the cutaneous blood-vessels is found in
the lamina inguinalis, where a chain of reddish points can be made out
with the naked eye; examined more carefully (Fig. 235 III) each reddish
point is found to be a complex loop of capillaries. They extend from
the skin to the hinder lymph-hearts, where they form a close network
which partially invests the lymph-hearts (Langer).
(2) The *lymphatics of the skin* (see also p. 252), like the arteries,
reach the deeper surface of the epidermis by coursing along the bands
of vertical fibres; they then form a network of capillaries with
rounded meshes (Fig. 235 I, II, IV), and lying immediately under the
epidermis, and a network which surrounds the various glands. The
lymphatic-capillaries are as a rule larger than the blood-capillaries.
The lymphatic network lies beneath the blood network, and the vessels
of the two systems branch independently (Langer).
In those parts where the glands are placed closely together this
arrangement is modified, and corresponds with the modifications found
in the blood-capillaries in these regions. The vertical branches divide
so as to form a network below the glands, and from this vertical
branches pass in the same direction between the glands to form a
secondary network on the superficial surface of the glands (Langer).
g. The *nerves* of the skin. The cutis is very richly supplied with
both medullated and non-medullated nerves. In the subcutaneous tissue
the nerves destined for the skin branch freely to form numerous fine
twigs, which, without actually inosculating, form a fine meshwork.
From the larger trunks numerous vertical branches pass vertically to
form a secondary network, from which both coarse and very fine twigs
pass to encircle the glands. The fine fibres which supply the glands
are non-medullated and possess oval nuclei; their diameter varies from
0·001–0·002 mm. The number of nerve-fibres is not much smaller than
that of the muscle-fibres (Engelmann). (See also Organs of Tactile
Sensation.)]
II. THE ORGANS OF TACTILE SENSATION.
The organs of tactile sensation are the nerve-plexus of the epidermis,
the touch-spots of Merkel, the lateral sense-organs, and the
touch-corpuscles of the tendons.
*a.* [The *nerve-plexus* of the epithelium is very incomplete as
compared with the plexus found in the epithelium of the cornea; here
and there a few non-medullated fibres have been traced a short distance
between the epithelial cells. No such mode of nerve-terminations in the
epithelium as is described by Eberth and Macullum in the tadpole can be
found in the adult.]
*b.* The *touch-spots*. What knowledge we possess of these organs is
due to the labours of Leydig, Ciaccio, Eberth, and more particularly
those of Merkel.
At the base of each papilla, which contains such a touch-organ, is
found a number of colourless, flattened cells, arranged either in a
single layer, or heaped up and connected with very fine nerve-fibres.
The flat surface of the cells is parallel to the surface of the body,
and they do not form a separate or circumscribed body, they are
therefore better spoken of as touch-spots than as true touch-bodies
(Merkel). The larger organs are found in the papillae, but smaller ones
may be found on any part of the skin.
[Illustration: Fig. 236.
I. Lateral sense-organ of tadpole of frog. Half-schematic.
_c_ Central zone (nerve-epithelium).
_Ml_ Membrana limitans.
_p_ Peripheral zone (sustentacular cells).
_R_ Hyaline tube.
II. Touch-corpuscle from the sheath of a digital tendon of the frog;
after Löwe. Schieck, Oc. O., Obj. 9. ]
These organs are best seen in the prominence or swelling upon the
supplemental toe during the breeding season; they are numerous on the
dorsal surface of the trunk, but occur most frequently on the under
surface of the hinder feet (_Planta pedis_). After the breeding
season the organs of the thumb undergo a retrogressive change, which
results in a network of spindle-shaped and branched cells with fibres
(Wiedersheim).
*c.* The *lateral sense-organs* attain their highest development in the
tadpole; in the adult the organs have undergone a retrogressive change,
the result of which is that the organs are diminished in size; the
whole organ sinks by the formation of a tube, which is then closed by
a mucous secretion, consequently the organ is functionless: with this
loss in function and change in position of the organs a corresponding
diminution of the ramus lateralis nervi vagi occurs (Merkel).
Each lateral organ (Fig. 236 I) consists of a slightly elevated
papilla, with the centre depressed, and in each may be distinguished a
central and a peripheral zone (_c_, _p_). The central zone consists of
a group of pear-shaped cells, with the narrower ends directed towards
the free surface; each is connected below with a nerve-fibril, while
above it bears a short, stiff cilium. The cilia are enclosed in a
delicate hyaline tube (_R_), which is open superficially, closed by the
papilla below; consequently the cilia are in direct contact with the
surrounding medium. The peripheral zone is a layer of pale, flattened,
cylindrical cells (_p_); they possess, at their upper borders, a
perforated _membrana limitans_ (_Ml_), through which the cilia pass.
These cells serve as a support to the central cells, and are themselves
surrounded by ordinary epithelial cells.
The distribution and arrangement of the lateral organs is alike in
fish and larval amphibia. They are most numerous on the head, where
they surround the eye, and are continued forwards to the snout and
on to the lower jaw. All these organs on the head are in connection
with the trigeminal nerve. A line of these organs passes from the
hinder part of the circumference of the eye along the gill-cover to
the neck, where the lines of opposite sides are usually, though not
constantly, joined by a transverse line of the same organs; thence
the lines are continued along the trunk to the tip of the tail. In
fish there exists, as a rule, only one pair of such longitudinal
lines (_Linea lateralis_); in anura-larvae, proteus, and in all
salamanders there are three pairs: of these one pair lies near the
vertebral column, the second at the junction of the flank with the
abdomen, and the third corresponds to the lateral line in fish
(Malbranc).
At an early developmental period each metamere possesses one pair of
such lateral organs; in later life, however, this simple arrangement
is lost, and each segment usually possesses a group of organs.
The organs of the trunk and tail are supplied by branches of the
Ramus lateralis nervi vagi. Both in fish and amphibia a reparative
process, by means of fission, occurs; as a consequence the organs are
found in various stages of development.
*d.* [The *touch-corpuscles* of Golgi and Löwe (Fig. 236 II) are found
on the joints of the digits. They are surrounded by connective-tissue
and are spindle-shaped; the two ends of the spindle are glassy in
appearance, the middle portion is fibrous. In the thickest part of the
corpuscle is a zone of nuclear bodies.
They are regarded as touch-bodies (Golgi and Löwe). Golgi (_l. c._)
describes two kinds of touch-organs in connection with muscle and
tendon; one class correspond with those just described, he names them
‘nervous muscle-tendon organs.’ The second class he compares with the
touch-bodies found in the conjunctiva.]
III. THE ORGANS OF TASTE.
The organs of taste are not confined to the surface of the tongue,
but are also found on the mucous membrane of the roof of the mouth,
especially in the neighbourhood of the vomerine teeth; on both roof and
floor of the mouth these organs can be traced to the commencement of
the oesophagus.
[The mucous membrane of the tongue possesses two kinds of papillae and
numerous glands.
*a.* The *filiform papillae* are the more numerous; they are conical
or thread-like in form, and consist of connective-tissue, with a few
striated muscle-fibres; they include blood-capillaries, but no nerves
have been traced into them (Leydig). They are covered with ciliated
epithelium and goblet-cells.
*b.* The *fungiform papillae* are much larger, and are paler than the
filiform papillae. The free ends of these papillae are broader than
the bases, and when the epithelium is removed the free ends present a
concavity. From the base to the border of the free surface each papilla
is covered with the usual oval, ciliated epithelium, but at this border
an abrupt transition takes place. The epithelium covering the end of
the papillae is of three kinds: goblet-cells, cylindrical cells, and
forked cells; the three forms of cells are quite characteristic, and no
intermediate transitionary forms are met with.
(1) The *goblet-cells* (Fig. 237 I) are arranged vertically to the free
surface of the papilla; they are from 0.020–0.024 mm. in length, and
from 0.01–0.02 mm. in diameter. In the lower third of the cell is found
a nucleus of about 0.008 mm. in diameter, and this encloses a nucleolus
of about 0.001 mm. in diameter. Close underneath the nucleus the cell
is contracted to form an irregular process or foot. The contents of
the cells are a very finely granular, transparent protoplasm. These
cells form the outermost part of the epithelium, covering the end of
the papilla; all the cells belonging to the same papilla are of the
same size. In consequence of the mutual pressure which they exert on
each other they present, in transverse section, six-sided outlines
(Fig. 237, 2). The nuclei of adjacent cells are placed at almost
exactly the same level. By the action of reagents on these cells
very remarkable forms are obtained, in consequence of the protoplasm
swelling and being forced upwards (Fig. 237, 5).
[Illustration: Fig. 237.
I. Various parts from the fungiform papillae; after Engelmann.
1. Nerves of a fungiform papilla. Magnified 450 times.
2. Surface view of the epithelium, after five minute’s action of
iodized serum. Magnified 600 times.
3. Goblet-cell with adjacent forked cell. Magnified 450 times.
4. Portion of the papilla, after removal of the goblet- and forked
cells; only cylindrical cells remaining. Magnified 400 times.
5. Goblet-cell, with swollen contents. Magnified 450 times.
6–13. Various forms of isolated forked cells. Magnified 450 times.
II. Sections of two glands of the tongue; after Biederman.
1. Resting-gland.
2. Gland after stimulation.
]
(2) The *cylindrical cells* (Fig. 237 I) have rounded free extremities,
which reach to the general surface of the epithelium; the remainder
of the cell is cylindrical except towards its lower extremity, where
it is slightly dilated and encloses an oval nucleus: the protoplasm
of the cells is very finely granular. These cells rest on the
connective-tissue of the papilla, and are in close juxtaposition, so
that several hundreds of them are found on one papilla.
The spaces between the upper parts of the cylindrical cells are
occupied by the goblet-cells and by the forked cells.
(3) The *third form* of cell found on the fungiform papillae are named
*forked cells* (Fig. 237 I) by Engelmann. The body of the cells has
an ellipsoidal form, is from 0.006–0.008 mm. in its longer diameter,
and 0.003–0.004 mm. in the shorter diameter. Processes arise from both
poles. The peripheral processes arise by a short common stem, which
then divides into two or rarely three branches; the whole process is
from 0.004–0.008 mm. in length, and is always just sufficiently long
to reach the general surface of the epithelium: when the peripheral
process is long the central is usually shorter, and _vice versâ_.
The central processes arise by a stem from 0.001–0.002 mm. in
thickness, which usually divides dichotomously. The length of this
process may be as much as 0.025 mm. or almost nil.
The forked cells are about twice as numerous as the goblet-cells, they
occupy the spaces between the cylindrical cells and the goblet-cells.
The branched central processes form a network on the connective-tissue
of the papilla, which is, at this point, perforated by a rich plexus
of fine non-medullated nerve-fibrils. It is not decided whether the
processes of various cells inosculate. Engelmann regards these forked
cells as the taste-cells and as the sensory nerve-endings.
The *bodies* of the fungiform papillae contain blood-vessels and
nerves, the latter enter as medullated nerves, but lose the medulla,
somewhat abruptly towards the upper end of the papilla, where they form
a sort of nerve-cushion (Nervenkissen, Engelmann).]
Taste-organs are also found on the roof and other parts of the mouth,
and present many points of resemblance to the lateral sense-organs.
Like them they present a peripheral zone and a central zone; the cells
of the latter, however, are not longer than the peripheral cells, and
possess no cilia (J. van der Hoeven, Merkel).
IV. THE NOSE.
The *anterior nares* or nostrils are two small openings, placed
directly in front of the anterior angle of the eye; the distance
between the eye and the corresponding nostril being, in the case of
adult animals, about five or six millimeters. The anterior nares are
surrounded by rims, which are contracted below, and so form very short,
tentacular-like prominences.
The *posterior nares* (choanae) are about four millimeters from
the anterior nares, consequently the long axis of the nose is,
approximately, of this length. (For the external muscles of the nose,
see p. 59.)
The *boundaries* of the *nasal cavities* are as follows:--the roof of
each cavity is formed by the dorsal plate of the sphenethmoid, the
nasal bone, and the premaxillary bone; the floor is formed by the vomer
and the palatine bone, the inner wall by the vertical septum of the
sphenethmoid, the outer wall by the premaxillary and maxillary bones,
the anterior wall by the premaxillary bone, and the posterior wall by
the sphenethmoid. The cartilaginous portion of the nasal skeleton (see
also p. 27) projects into the general cavity and subdivides it into
various sinuses, which have been the subject of careful investigation
by Born and Wiedersheim.
*a.* The *nasal cavities* are best examined by means of serial
transverse sections; in a section through the anterior nares
(Figs. 238, 239) there will be seen three sinuses on either side:--
(1) The *superior sinus* (_on_) is large, rounded, and placed against
the cartilaginous septum; the sinus is lined with olfactory epithelium.
Posteriorly the sinus extends beyond the posterior nares, and is
bounded by the anterior surface of the sphenethmoid. In front it ends
in a rounded concavity, likewise lined with olfactory mucous membrane.
Opposite the anterior nares the cavity is partially subdivided, by a
longitudinal process on the floor, into two cavities; the anterior
nares open into the external chambers, and therefore not directly into
the main cavity of the superior sinus. The superior sinus communicates
with the inferior sinus by a narrow, almost vertical, slit.
(2) The *inferior sinus* (_un_) is narrow and flattened from above
downwards; it is placed against the maxillary bone, and represents the
maxillary sinus of the frog. Externally it possesses a descending arm.
The inferior sinus is continued backwards and opens on its inner side
into the posterior nares, or rather into the mouth. The descending arm
extends only a short distance forwards, to terminate near the point
where the superior and inferior sinuses communicate by only a narrow
opening. This sinus is on the whole broader in front than behind, and
has a general direction from without, inwards and forwards underneath
the superior sinus.
[Illustration: Fig. 238.]
[Illustration: Fig. 239.
Frontal sections through the nose of two tadpoles; after G. Born.
_A_ Anterior naris.
_b_ Cartilaginous floor.
_C_ Cutis.
_d_ Cartilaginous roof.
_Ep_ Epidermis.
_gi_ Intermaxillary gland.
_gni_ Lower nasal gland.
_gns_ Upper nasal gland.
_K_ Maxillary sinus.
_l_ Concha narium (os lachrymale).
_m_ Maxillary bone.
_MS_ Oral mucous membrane.
_ok_ Cartilage.
_on_ Upper blind sac.
_R_ Pharyngeal gland.
_S_ Nasal septum.
_se_ Septum between the upper and lower
nasal cavity.
_sn_ External blind sac.
_T_ Trabeculae.
_Th_ Lachrymal duct.
_un_ Lower blind sac.
]
(3) The *lateral sinus* (_sn_) is situated in the partition between
the superior and inferior sinuses, or rather between the external
chamber of the upper sinus and the inferior sinus. The lateral sinus
is triangular in form, being narrow in front and broad behind; at its
inner posterior angle it opens on the free border of the horizontal
partition between the superior and inferior sinuses; this opening is,
however, continued along its roof, so that the lateral sinus opens also
into the superior sinus.
*b.* The *nasal cartilages*. The two nasal cavities are completely
separated by the cartilaginous septum (Figs. 238 and 239 _S_), and
are for the most part lined by cartilage. The anterior end is formed
of concave cartilages, while the posterior, being situated in the
sphenethmoid, is usually more or less ossified in the adult. The
posterior wall has two openings: a larger near the septum for the
olfactory nerve, and a smaller, more externally, for the nasal branch
of the trigeminal nerve.
The anterior wall is more complex than the posterior, being thicker in
the middle than at the sides, and possessing three blind sacs for the
three sinuses. From the anterior wall two processes project backwards
between the sacs and enclose them more or less completely.
Of the three sacs or cavities only the lower is completely surrounded
by cartilage. The upper sac is in part bounded by a shell-shaped,
concave cartilage (_Concha narium_, of various authors; _Os
lachrymale_, Born), which covers it anteriorly and externally, and is
attached by a small base to the roof of the lower sac (Fig. 239, _l_),
its upper border bounding the anterior naris (Fig. 15). The upper and
external parts of the upper sac have no cartilage. The cartilages of
the outer wall of the lower, blind sac extend backwards to the point
where the maxillary sinus commences to descend: the roof, however,
is prolonged further backwards by two small cartilaginous processes;
the inner is short, the outer forms the roof of the descending arm of
the sinus, and joins a cartilaginous process, which commences at the
anterior portion of the roof of the nasal cavity, passes backwards and
downwards to a broad plate, and forms an incomplete outer wall to the
nasal cavity. There are also three cartilaginous processes--α. One
arising from the outer side of the floor at the level of its junction
with the anterior wall; it is a flattened process and passes outwards,
and bifurcates at its end to meet the premaxillary and maxillary bones
(this is the Oberkieferfortsatz of Ecker), (p. 28, Fig. 14 _n″_). β. A
delicate process on either side, described by Wiedersheim (see p. 280).
γ. The third pair of processes are fully described for the first time
by Born; each arises at the lower border of the corresponding _Concha
narium_, passes forwards and downwards under the ascending process of
the premaxillary to the point where process β is attached to this
bone. The processes are flat and approach one another obliquely; in
older animals they are united at the point of contact.
At the junction of the anterior wall, the septum, and the floor is a
large aperture in the cartilaginous capsule, through which passes the
chief nasal branch of the trigeminus, which supplies numerous branches
to the intermaxillary gland.
*c.* The *glands* of the *nasal region* are Bowman’s glands, the
intermaxillary glands (Wiedersheim), the lower nasal gland (Born),
the upper nasal gland (Born), the pharyngeal gland (Born), and the
lachrymal duct.
[Illustration: Fig. 240.
I. A. Bowman’s glands in situ from _Rana temporaria_; after C. K.
Hoffmann. Magnified 150 times.
B. Section of Bowman’s gland; after C. K. Hoffmann. Magnified 300
times.
II. Vessels of nasal mucous membrane of _Rana esculenta_; after Langer.
Blood-vessels striped, lymphatics shaded.
]
(1) The *intermaxillary gland* (see p. 280).
(2) The *lower nasal gland* is placed along the septum and extends
as far back as the posterior nares, opening by its ducts (Figs. 238
and 239 _gni_) into the inferior blind sac of the nasal cavity. In
histological structure it corresponds with the intermaxillary glands,
except that the glandular tubes are somewhat smaller, and the glandular
epithelium stains somewhat less easily with carmine (Born).
(3) The *upper nasal gland* occupies the space between the _Concha
narium_ (_Os lachrymale_, Born) and the neighbouring cartilages, it
also surrounds the anterior naris and the opening of the lachrymal
canal (Figs. 238 and 239 _gns_). The numerous ducts open on the mucous
membrane covering the oblique cartilage (above described, as passing
from in front, downwards and backwards, and forming an incomplete outer
wall of the cavity), and its hinder prolongation.
(4) The *pharyngeal gland* is placed transversely behind the posterior
nares, and surrounds the vomerine teeth. A portion of the ducts open
into the posterior nares, the remainder on the mucous membrane of the
pharyngo-oral cavity at two symmetrically placed points (Fig. 238 _R_).
(5) The *lachrymal duct* (see p. 428) opens into the nasal cavity at
the point where the lateral sinus opens into the external chamber of
the superior nasal sinus.
(6) [The *glands* of *Bowman* (Fig. 240 I) are freely distributed
in the nasal mucous membrane. Each gland is usually rounded or
flask-shaped, and consists of a single layer of large epithelial cells
possessing distinct nuclei and nucleoli. The epithelium of the glands
possesses no basement membrane (M. Schultze and Hoffmann[86]), but is
bounded externally by a layer of nerve-fibres and connective-tissue.
[Footnote 86: Paschutin describes a basement membrane.]
The glands situated more superficially have straight ducts opening
on the surface; those placed more deeply have usually curved ducts
(Paschutin).]
*d.* The *mucous membrane* of the nasal cavities. That part of
the superior sinus immediately around the anterior naris is lined
with stratified epithelium; the rest of the nasal cavity is lined
with columnar ciliated epithelium The epithelial layer rests on a
subepithelial network, and this again on a submucous connective-tissue
layer possessing numerous vessels and nerves.
(1) The *epithelial layer* (Fig. 241) consists of columnar cells,
which in the olfactory region are of two kinds; in other regions
the epithelium consists of closely-applied ciliated, thick cells,
possessing large oval nuclei, and having irregular, branched bases or
‘feet.’ The cells are 0.032–0.048 mm. long; the nuclei 0.016–0.018 mm
long, and 0.006–0.008 mm. broad. The free borders of the cells bear a
number of fine cilia.
In the olfactory region a second set of cells, olfactory cells, are met
with; these cells (Fig. 241 II) possess each an oval body, enclosing
a large nucleus, and a peripheral and central process. The peripheral
processes reach to the general surface of the surrounding epithelium
and there terminate in a number (5–8) of stiff cilia; these cilia are
sometimes 0.09 mm. long, they are thicker at their bases than the
ordinary cilia (Schultze); according to Hoffmann, a second system of
stiffer and longer cilia is met with; of which each olfactory cell
possesses as a rule only one. The bodies of the olfactory cells are
0.009–0.010 mm. long, and 0.007–0.008 mm. broad; the peripheral
processes vary considerably in length, according to the position of the
body (0.03–0.05 mm.). The central processes vary from 0.02–0.03 mm.
in length. The peripheral processes are considerably thicker than
the central processes. No _membrana limitans olfactoria_ has been
discovered in the frog.
(2) The *second layer* consists of a network of processes belonging
to the bases of the central processes of the superimposed epithelial
and olfactory cells. Numerous highly refractive nuclei possessing
nucleoli are situated in the meshes of this network; they correspond in
all particulars with the nuclei of the olfactory cells (M. Schultze).
According to Exner the branched processes of the epithelial cells and
of the olfactory cells unite to form a complex plexus. Other observers,
Paschutin, Cissoff, v. Brunn, Schultze, and Hoffmann oppose this view,
and hold that the central processes of the olfactory cells do not
unite with the processes of the epithelial cells, but that they are in
direct continuity with the fibrils of the olfactory nerve. This view is
probably correct.
[Illustration: Fig. 241.
Separations from the olfactory mucous membrane of _Rana temporaria_;
after C. K. Hoffmann.
I. Surface view of the olfactory mucous membrane. Magnified 350 times.
II. Epithelial and olfactory cells. Magnified 600 times.
III. Epithelial cells. Magnified 600 times.
]
The submucous layer has a loose connective-tissue matrix, which
encloses the glands, nerves, and vessels; according to Paschutin
two pigment-layers may be distinguished: the one, immediately under
the middle layer of this mucous membrane, is continuous and deeply
pigmented; the second is deeper and does not form a continuous layer.
This layer is extremely rich in blood-vessels and lymphatics (Langer
and Paschutin), (Fig. 240 II). The lymphatics are relatively very large
and are very numerous (Langer).
In this layer the central processes of the olfactory cells form bundles
of fibres, lying parallel with the surface of the mucous membrane
(Paschutin, Cissoff, and Schultze).]
V. THE EAR.
(Re-written by the translator from Das Gehörorgan der Wirbelthiere,
by G. Retzius, 1881.)
The organ of hearing is divisible into two parts, the tympanum or
middle ear, and the labyrinth or internal ear; an external ear is
absent, unless a very slight depression of the tympanic membrane be
regarded as such.
A. The *tympanum* (_Cavum tympani_) is a cavity, bounded externally by
the tympanic membrane and internally by the capsule of the internal
ear; it communicates by means of the Eustachian tube (tuba Eustachii)
with the pharyngo-oral cavity (Fig. 178).
*a.* The *tympanic membrane* lies immediately underneath the skin, but
can be separated from that structure; externally it possesses a very
slight depression, the only trace of an external ear found in the frog.
The tympanic membrane is of a rounded oval form, being a little wider
in the transverse than in the longitudinal diameter; the membrane is
directed outwards.
After detaching the skin (Fig. 242 I) the membrane is seen to be
attached by its circumference to a ring of cartilage (_Annulus
membranae tympani_; see also p. 26) (_at_); the ring is attached
anteriorly and above to the squamosal bone (_sq_), and in the rest
of its circumference to the surrounding soft parts, _i.e._ the _M.
depressor maxillae_ (_dm_), the _M. temporalis_ (_t_), and their
fasciae. In the middle of the membrane is a small, rounded, white
part (_col_) which can be traced backwards and upwards towards the
circumference.
The membrane consists of fibres of connective-tissue which radiate
peripherally from the central point of attachment of the columella;
in the peripheral portion unstriated muscular fibres are also found
(Leydig).
[Illustration: Fig. 242.
I. The tympanic membrane of _Rana esculenta_; natural size. After
Retzius.
II. The tympanum as seen after removing the tympanic membrane; natural
size. After Retzius.
_at_ Annulus membranae tympani.
_col_ Columella.
_ct_ Fissure-like cavity.
_dm_ M. depressor maxillae.
_mt_ Tympanic membrane.
_sq_ Squamosal.
_t_ M. temporalis.
]
Internally the tympanic membrane is covered by columnar epithelium, a
continuation of the mucous membrane lining the tympanic cavity.
*b.* The *tympanic cavity* (Fig. 242 II) is seen, after removing the
tympanic membrane, as a flattened, funnel-shaped cavity. The walls of
the cavity are lined with a pigmented mucous membrane, under which the
cartilaginous ring (_annulus membranae tympani_) extends internally
to form the greater part of the wall of the cavity. The cavity is an
elongated oval slit (Fig. 242 II, _ct_), with its longer axis directed
from above and in front, downwards and backwards, and leading inwards;
it is bounded above, below, and in front by the squamosal, behind by
the soft parts; above in the roof is the cartilaginous part of the
_columella_. The inner or deeper portion of the tympanic cavity is
bounded in front by the squamosal, and by the squamous process of the
prootici (_proc. squamosus prootici_) in front and above; internally
by the cartilage (primordial-cranium) between the prootic and the
exoccipital; behind by the _M. depressor maxillae_. This part of the
cavity is rounded and covered with mucous membrane, and has in its
roof the bony part of the columella, which covers the _foramen ovale_
(_fenestra ovalis_) by its oval, widened end-piece. This deeper portion
of the cavity communicates by a short, wide Eustachian tube with the
pharyngo-oral cavity; the tube is wide and is of a rounded oval form in
section: anteriorly, externally, and internally it is bounded by the
pterygoids, posteriorly by soft parts, in which is embedded the styloid
process.
The tympanic cavity can be examined from without after removing the
tympanic membrane, or from below by means of the Eustachian tube.
*c.* The *columella auris* (Figs. 12, 243) is described by Retzius as
consisting of three portions, of which the middle is bony, the external
and internal cartilaginous. Parker divides it into four parts (see
pp. 25, 26).
The *extrastapedial* (Fig. 243 _a′_, _a″_) is attached to the middle
of the tympanic membrane by the oval surface opposite _a′_, and is
attached by the process _a‴_ to the _annulus tympanicus_; this process
of Retzius is the *suprastapedial* of Parker.
The *mediostapedial* (Parker), or middle bony piece of Retzius
(Figs. 12 _a′_, 243 _b_, _b′_), is narrow externally but widens
internally to articulate with the interstapedial. Just before reaching
the latter it gives off a process (_b′_), to which are attached a few
fibres of striated muscle (_m_).
[Illustration: Fig. 243.
The columella; after Retzius. Magnified eight times.
A. Seen from above.
B. Seen from behind.
_a′_ Extrastapedial (Parker). Outer cartilaginous portion
attached to middle of tympanic membrane (Retzius).
_a″_ Attachment of extrastapedial to mediostapedial.
_a‴_ Suprastapedial (Parker). Portion embedded in mucous
membrane (Retzius).
_b′_ Mediostapedial (Parker). Bony part (Retzius).
_b″_ Process of mediostapedial.
_c_ Interstapedial (Parker). Inner cartilaginous piece
(Retzius).
_m_ Insertion of small muscle.
]
The *interstapedial* (Figs. 12 _a_, 243 _c_) is cartilaginous; it is
thick with a sharply cut-off, slightly concave end, which is placed
against the _fenestra ovalis_. The inner surface of the interstapedial
is, however, distinctly larger than the opening of the _fenestra
ovalis_, consequently it does not fit in accurately, but is attached to
the border of the opening by means of connective-tissue; the margins of
the _fenestra ovalis_ are hollowed (Fig. 245 II) so as to form a _fossa
fenestrae ovalis_, and it is really to the margin of this fossa that
the connective-tissue capsule of the interstapedial is attached.
B. The labyrinth or internal ear is contained in a capsule formed of
bone and cartilage.
*a.* The *capsule of the labyrinth* (Fig. 244) is formed of two bones,
the prootic and the exoccipital (according to Hasse this includes
the opisthotic), which are united by cartilage belonging to the
primordial-cranium. The fronto-parietal, squamosal, and parasphenoid
take only an indirect part in its formation.
On the whole the anterior half of the capsule is formed by the prootic,
and the hinder half by the exoccipital; the cavity has its long axis
directed from within and above, downwards and outward; the cavity is
comparatively large and rounded, and contains the membranous ear.
Four surfaces can be distinguished: a supero-external, an
interno-inferior, an anterior, and a posterior (Retzius).
(1) The *supero-external surface* is divided into two parts by a
strong, transverse, bony ridge, the _processus squamosus prootici_.
The upper half is concave, is directed upwards and outwards, and is
formed by the prootic; it is separated from the anterior surface by
a bony ridge, which marks the position of the anterior semicircular
canal. Posteriorly and medianly it is separated from the posterior
surface by a cartilaginous ridge, running from above, downwards and
outwards, which marks the position of the posterior semicircular canal.
The cartilaginous hinder root of the _processus squamosus prootici_
arises in the cartilaginous ridge just mentioned, and runs outwards and
forwards, covering the external semicircular canal.
[Illustration: Fig. 244.
Antero-posterior section through the capsule of the right labyrinth of
_Rana esculenta_; after Retzius. Enlarged five times.
_ac._ Aquaeductus cochleae.
_av._ Aquaeductus vestibuli.
_cp._ Posterior semicircular canal.
_cra._ Canalis rami anterioris acustici.
_crp._ Canalis rami posterioris acustici.
_fr._ Fenestra rotunda.
_fsc._ Fovea sacculi et cochleae.
_ft._ Trigeminal foramen.
_kn._ Cartilaginous suture.
_ol._ Exoccipital.
_pr._ Prootic.
_ps._ Parasphenoid.
]
The lower half of the supero-external surface (under the _processus
squamosus_) is irregularly concave; immediately under the _proc.
squamosus_ is a shallow groove in the prootic; it is continued on the
exoccipital to the jugular foramen. The remaining part of this surface
consists of a rounded cartilage, and is part of the primordial-cranium
cartilage between the prootic and the exoccipital; posteriorly it has
a small oval aperture, the _foramen ovale_ (_fenestra vestibulare_),
which with the groove is covered by the _columella_. Above the aperture
the cartilage narrows and is continued to the _processus squamosus_.
(2) The *posterior surface* is directly continuous with the
supero-external surface, and is formed by the exoccipital. This surface
lies behind the ridge formed by the posterior semicircular canal, it
is concave, and has two small apertures, separated by a narrow, bony
process, and situated near the jugular foramen; these are the _foramen
rotundum_ (_fr._) and the _aquaeductus cochleae_ (_ac._).
(3) The *anterior surface* is altogether bony and formed by the prootic
(_pr._); the anterior surface of this part of the wall is continuous
with the surface of the cranium, and abuts on to the large trigeminal
foramen (_ft._); below it is continuous with the under surface of the
cranium, below and externally it articulates with the pterygoid.
(4) The *interno-inferior surface* is as a whole hollowed internally,
the upper part being pushed in towards the cranial cavity. It is formed
by the prootic anteriorly, by the exoccipital posteriorly, and is
completed by the cartilage lying between these bones. In the middle
of the upper part of the cartilage is a small oval opening (_av._),
the _ap. aquaeductus vestibuli_: about midway between this aperture
and the jugular foramen is a second opening in the cartilage (_cra._),
the opening of the _canalis rami anterioris (vestibularis) acustici_:
a little behind and above this is the opening of the _canalis rami
posterioris (cochlearis) acustici_, situated in the exoccipital. The
cartilage between the prootic and exoccipital in the lower half of the
interno-inferior surface rests on the parasphenoid.
*b.* The *position* of the *soft parts* in the capsule. The large
outer, rounded part of the cavity contains the saccule and cochlea
(_fovea sacculi et cochleae_) (_fsc._). Above, the cavity is more
irregular, and contains the utricle and the _sinus utriculi superior_.
In front and externally, imbedded in a deep groove, are the anterior
and external ampullae (_fovea ampullae anterioris et amp. externae_);
to these are attached the corresponding semicircular canals. The
anterior semicircular canal opens above and externally into the
canal of the _sinus utriculi superior_; the posterior passes into a
groove for the posterior ampulla (_fovea ampullae posterioris_), and
opens above and internally into the posterior semicircular canal.
The external semicircular canal courses in the _processus squamosus
prootici_, the posterior in the cartilage (Fig. 244 _cp_) between the
prootic and exoccipital, and the anterior in the prootic. The upper
and posterior part of the anterior semicircular canal is imbedded in
cartilage, on which rests the parasphenoid.
*c.* The *perilymphatic space* (Fig. 245 I and II). The membranous
labyrinth does not occupy the whole space enclosed by the hard parts
but is surrounded by the perilymphatic space, which contains the
perilymph. The periosteum and perichondrium form the outer lining of
the space, and are for the most part pigmented:
The perilymphatic space is widest in the lower part of the organ, in
the region of the _fovea sacculi et cochleae_, especially externally
and behind (_per_); in front it is much narrower (_per^1_). A little
higher, in the region of the _tegmentum vasculosum_, the space is
wanting, as the membranous labyrinth is here attached to the periosteum.
Around the utricle and saccule the space is comparatively wide; it is
continued into the bony canals and ampullae. In the semicircular canals
the space is wider on the concave side than on the convex side, the
membranous canals being placed eccentrically, as are also the ampullae,
though to a less extent. The periosteum and perichondrium lining this
cavity form a very delicate, pigmented membrane, formed of numerous
fine elastic fibres which cross each other irregularly; its inner
surface is lined with an incomplete layer of branched protoplasmic
cells with large oval nuclei. From this membrane numerous irregular
bundles of fibres, in the form of trabeculae, pass into the space and
form a rich network, which is attached internally to the outer surface
of the membranous labyrinth and holds it in position. Free nucleated
leucocytes are occasionally met with in the meshes of this network. The
perilymphatic space is prolonged into two subsidiary cavities:--
[Illustration: Fig. 245.
The membranous labyrinth of _Rana esculenta_, within its natural
covering of periosteum; after Retzius.
I. Seen from the side; magnified ten times.
II. The hinder half; magnified ten times. Seen obliquely from above,
and in front, and from the side.
_aa_ Anterior ampulla.
_adf_ Apertura fenestrae ovalis.
_al._ Apertura lagenae.
_ap._ Posterior ampulla.
_apb._ Opening into the pars basilaris.
_ca_ Anterior semicircular canal.
_ce_ External semicircular canal.
_cp_ Posterior semicircular canal.
_dfo_ Ductus fenestrae ovalis.
_dp_ Ductus perilymphaticus.
_dp′_ Saccus perilymphaticus.
_l._ Lagena cochlea.
_ms._ Macula sacculia.
_pb_ Pars basilaris cochleae.
_per_ Wider part of perilymphatic space.
_per^1_ Narrower part of perilymphatic space.
_ra._ Ramus anterior.
_rn._ Ramulus neglectus.
_rp._ Ramus posterior.
_rs._ Ramulus sacculi.
_s._ Saccule.
_sfo_ Saccus fenestrae ovalis.
_spl_ Saccus perilymphaticus.
_tv_ Tegmentum vasculosum.
_u_ Utricle.
]
(1) The *ductus fenestra ovalis* (Retzius), (Fig. 245 _dfo_) commences
as an opening (_adf_) immediately opposite the _foramen ovale_ of the
hard capsule, which leads into a moderately large canal, the structure
under consideration. It passes forwards and outwards through the
_fenestra ovalis_ between the interstapedial and the outer wall of
the capsule into the oval depression (_fossa fenestrae ovalis_), and
rapidly widens to form a short, flattened, blind sac (_saccus fenestrae
ovalis_), which is lodged in the fossa (_sfo_). Its walls are thin and
pigmented.
[Illustration: Fig. 246.
Part of the outer wall of the perilymphatic space: after Retzius.
Vérick’s Syst., Obj. III, Oc. 3.
_per._ Periosteum.
_pg._ Perilymphatic network.
_zn._ Leucocytes.
]
(2) The *ductus perilymphaticus* (Hasse), (Fig. 245 _dp_) passes above
and behind the _ductus fenestrae ovalis_, behind the auditory-nerve,
and near the cochlea, then behind and above the _lagena_ to the
_aquaeductus cochleae_ (Fig. 244 _ac_), where it forms a short, wide
tube, which passes backwards and inwards through this canal to the
_canalis jugularis_; here it lies close to the nerves and forms a short
oval sac (_saccus perilymphaticus_) (_dp′_), which communicates with
the sub-arachnoid space of the cranial cavity by means of a tube from
the neck of the sac. The walls of this structure are thin and formed
of connective-tissue with very few pigment-cells. The other extremity
of the tube passes to the _pars basilaris_ and under the _sinus post.
utri._, between it and the _pars neglecta_; it then courses to the
outer side of the hinder end of the external semicircular canal: the
tube then bends downwards to the outer side of the utricle and saccule
to open into the general perilymphatic space.
*d.* The *membranous labyrinth* (Figs. 247, 248) has the following
parts: the utricle and _sinus superior_, the _recessus utriculi_,
the anterior semicircular canal and anterior ampulla, the external
semicircular canal and external ampulla, the posterior semicircular
canal and the posterior ampulla, the saccule, _ductus endolymphaticus_,
and _saccus endolymphaticus_, the _pars neglecta_, the _lagena
cochleae_, the _pars basilaris cochleae_, and the so-called _tegmentum
vasculosum_.
In addition the following nerve-terminations can be distinguished: (1)
The _macula ac. recessus utriculi_, (2) the three _cristae acusticae
ampullorum_, (3) the _macula ac. sacculi_, (4) the _macula ac.
neglecta_, (5) the _papilla ac. lagenae cochleae_, and (6) the _papilla
ac. basilaris cochleae_.
The auditory nerve divides immediately beyond its origin from the
_medulla oblongata_ to form a _ramus anterior_ and a _ramus posterior_,
which course alongside each other for a short distance, the latter
lying behind and above the former. The _R. anterior_ runs forwards
and outwards under the utricle, giving off the _R. sacculi_, which
runs downwards and outwards; the _R. rec. utriculi_ is then given off
as a number of fibres, which run upwards and forwards; the main nerve
then divides to form the _R. ampullae anterioris_ and the _R. ampullae
externae_, which course together for a short distance and then separate
to reach their respective ampullae. The _R. posterior_ runs backwards
and outwards, gives off the _R. lagenae_, and then divides to form the
_R. neglectus_, running upwards, the _R. basilaris_ running downwards
and backwards, and the _R. ampullae posterioris_ which courses
backwards and outwards.
(1) The *utricle* (_utriculus_) (Figs. 247 and 248 _u_) is irregularly
cylindrical in form: commencing at the _recessus utriculi_ it passes
forwards and outwards; then backwards, inwards, and upwards, to
terminate at the _sinus posterior_, where it is slightly contracted. At
about its middle it is divided into an anterior and a posterior part
by an incomplete, sickle-shaped partition, formed by the posterior
semicircular canal opening obliquely into the utricle, and so causing a
fold in the posterior wall: on the anterior wall there is no fold; the
aperture left in the partition is the _apertura utriculi_.
The posterior part of the utricle receives the _sinus superior_, which
is formed by the junction of the two vertical semicircular canals. The
anterior part of the utricle receives the hinder dilated end of the
external semicircular canal by an opening in its posterior wall, close
to the _apertura utriculi_. In the lower wall or floor is the narrow
opening leading into the _saccule_ (_canalis utriculo-saccularis_):
this opening is placed with its long axis parallel to the long axis
of the utricle, with its broader end posterior, and the narrower end
anterior.
(2) The *recessus utriculi* (Figs. 247 and 248 _rec_). The anterior
end of the utricle widens and curves downwards and outwards to form
the _recessus utriculi_; on its floor is a thin, kidney-shaped plate
or otoliths, resting on the _macula ac. recessus utriculi_ (_mu_),
which receives the _ramulus rec. utriculi_; under it the _ramulus amp.
anterioris_ and the _ramulus amp. externae_ run forwards and close
together to reach their respective ampullae, which are close together
at the antero-external wall of the _recessus utriculi_. The otolith
is a glassy, homogeneous plate, with numerous vacuole-like spaces and
striated borders; it covers the whole of the _macula_.
[Illustration: Fig. 247.]
[Illustration: Fig. 248.
The right membranous labyrinth of _Rana esculenta_; after Retzius.
Magnified 20 times. Fig. 247 seen from the inner side; Fig. 248 seen
from the outer side.
_aa_ Anterior ampulla.
_ae_ External ampulla.
_ap_ Posterior ampulla.
_apn_ Apertura partis neglectae.
_au_ Apertura utriculi.
_ca_ Anterior semicircular canal.
_ce_ External semicircular canal.
_cp_ Posterior semicircular canal.
_cus_ Canalis utriculo-saccularis.
_de_ Ductus endolymphaticus.
_l_ Lagena cochleae.
_mn_ Macula acustica neglecta.
_ms_ Macula acustica sacculi.
_mu_ Macula acustica recessus utriculi.
_pb_ Pars basilaris cochleae.
_pl_ Papilla ac. lagenae.
_ppb_ Papilla ac. basilaris.
_raa_ Ramulus ac. anterioris.
_rae_ Ramulus amp. externae.
_rap_ Ramulus amp. posterioris.
_rb_ Ramulus basilaris.
_rec_ Recessus utriculi.
_rl_ Ramulus lagenae.
_rn_ Ramulus neglectus.
_rs_ Ramulus sacculi.
_s_ Saccule.
_sp_ Sinus utriculi posterior.
_ss_ Sinus utriculi superior.
_tv_ Tegmentum vasculosum.
_u_ Utriculus.
]
(3) The *anterior ampulla* and *semicircular canal* (Figs. 247, 248,
_aa_, _ca_). The anterior ampulla is a rounded, oval vesicle, with
a depressed roof (Fig. 250 I); on the floor is a transverse low
septum, which bears the _crista acustica_ (_cr_) on its free border;
seen from above the _crista acustica_ (Fig. 249 II, _aa_, _cr_) has
concave borders anteriorly and posteriorly; the ends are broad,
rounded, and somewhat raised; and in the middle it presents a small
elevation (Fig. 249 _cr_). On the _crista acustica_ rests the _cupula
terminalis_ (Fig. 250 I, _cu_); this is arched above but of the same
form as the _crista acustica_ below, from which it is separated by an
even slit-like space; the ends are not rounded but hollowed out. The
substance of the _cupula_ is very soft and has parallel striations,
formed of fine fibres and running from above downwards; it separates
very easily from the _crista acustica_. The anterior ampulla is
directed forwards, outwards, and slightly upwards, to open into the
anterior semicircular canal (_canalis m. anterior_) (_ca_), which
curves first upwards and forwards, then backwards, inwards, and
upwards, to open by means of a slightly dilated end into the _sinus
superior utriculi_.
(4) The *external ampulla* and *semicircular canal* (Figs. 247, 248
_ae_, _ce_). The external ampulla lies immediately external to the
anterior ampulla; it also is an oval vesicle, and corresponds with the
anterior ampulla in size and shape, except that the roof is higher.
The roof is directed backwards, the floor forwards; the _septum
transversum_ is low, placed vertically, and bears a triangular,
slightly depressed _crista acustica_: the broader, rounded end of the
_crista_ is directed upwards, the apex downwards. The corresponding
_cupula terminalis_ is relatively high, and is of the same shape as
the _crista_, and is striated. The external ampulla is continuous with
the external semicircular canal (_canalis m. externus_) (_ce_), which
courses outwards and backwards; then backwards, inwards, and slightly
upwards, touches the roof of the posterior ampulla; then curves
forwards and inwards to terminate by a slightly dilated end in the
anterior part of the utriculus.
(5) The *posterior ampulla* and *semicircular canal* (Figs. 247,
248, and 249 _ap_, _cp_). The posterior ampulla commences at the
posterior end of the _sinus post. utriculi_, and is directed outwards
and backwards. It corresponds in all other points with the anterior
ampulla. The posterior semicircular canal (_ce_) (_canalis m. post._),
into which the ampulla opens, curves upwards, inwards, and forwards, to
open into the upper end of the _sinus superior_.
[Illustration: Fig. 249.
The membranous labyrinth of _Rana esculenta_; after Retzius.
I. Part of membranous labyrinth to show relations of the ductus and
saccus endolymphaticus to the cochlear part; magnified.
II. The recessus utriculi and the external ampulla; magnified.
III. To show tegmentum vasculosum, pars basilaris, pars neglecta, etc.
IV. To show relations of the cochlear part to the pars neglecta.
_aa._ Ampulla anterior.
_ae._ Ampulla externa.
_al._ Apertura lagenae.
_ap._ Posterior ampulla.
_apn_ Apertura partis neglectae.
_au._ Apertura utriculi.
_ca._ Canalis m. anterior.
_ce._ External semicircular canal.
_cp._ Posterior semicircular canal.
_cpb._ Opening into pars basilaris.
_cr._ Crista acustica.
_cus._ Canalis utriculo-saccularis.
_de._ Ductus endolymphaticus.
_dp._ Ductus perilymphaticus.
_l._ Lagena cochleae.
_ma._ Macula ac. recessus utriculi.
_mn._ Macula ac. neglecta.
_mp._ Membrana basilaris.
_pb._ Pars basilaris cochleae.
_pe′._ Dark spot on either side of
crest of ampulla.
_pl._ Pars ac. lagenae.
_pn._ Pars neglecta.
_ppb._ Papilla ac. basilaris.
_ra._ Ramus anterior.
_raa._ Ramulus amp. anterioris.
_rae._ Ramulus amp. externa.
_rap._ Ramulus amp. posterioris.
_rb._ Ramulus basilaris.
_rec._ Recussus utriculi.
_rl._ Ramulus lagenae.
_rn._ Ramulus neglectus.
_rp._ Ramus posterior.
_rs._ Ramulus sacculi.
_s._ Saccule.
_sp._ Posterior semicircular canal.
_spl._ Saccus perilymphaticus.
_ss._ Sinus utriculi superior.
_tv._ Tegmentum vasculosum.
_u._ Utricle.
]
(6) The *saccule* (_s_), *ductus endolymphaticus* (_de_), and the
*saccus endolymphaticus* (Figs. 247, 248, 249). The saccule (_s_) is
an oval vesicle, placed under the anterior part of the utricle and
directed outwards and downwards; below it is flattened in a direction
from in front and within, outwards and backwards; above it is wider. In
the inner and anterior surface is the rounded, oval _macula acustica
sacculi_ (Figs. 247 and 248 _ms_), to which is distributed the _R.
sacculi_ (_rs_) from above; a large otolith rests on the macula and
occupies a large portion of the cavity, more especially the lower
portion. The tubular _ductus endolymphaticus_ (_de_) arises by a narrow
oval opening placed in the upper and inner part of the wall, runs
upwards and to the angle between the utricle and the _sinus superior_,
continues in the same direction for a short space, and then curves
inwards to pierce the _apertura aquaeductus vestibuli_, and so reach
the cranial cavity. It then forms a large, thin-walled sac (_saccus
endolymphaticus_), placed between the brain and cranium. The sac is
very vascular and contains crystalline otoliths.
(7) The *pars neglecta* (Figs. 247, 248, 249) was described by Hasse
as the ‘first part of the cochlea’ (‘Anfangstheil der Schnecke’), but
according to Retzius it does not belong to the cochlea. It is placed
above and in front of the _pars basilaris cochleae_, above and a little
behind the _lagena cochleae_, therefore above the upper and posterior
part of the saccule, and under the middle part of the utricle. It is
really a prolongation of the saccule, with which it communicates by
an elongated oval opening placed externally and immediately below the
opening of the _canalis utriculo-saccularis_. It is an oval vesicle,
with its roof intimately united with the lower wall of the utricle;
anteriorly it is broad, posteriorly narrowed. The _macula acustica
neglecta_ is attached to the roof of the vesicle and consists of an
anterior heart-shaped and a posterior semilunar portion united by a
narrow connecting piece (Fig. 250 III and VII). The _ramulus neglectus_
divides into two branches, which supply the two parts of the _macula_.
On the _macula acustica neglecta_ rests the _membrana tectoria_
(Deiters); the membrane is S-shaped, with the anterior end narrow, the
posterior broad (Fig. 250 VII); the borders of the membrane are pierced
by numerous small round holes, the central part has smaller and fewer
perforations, and is finely striated. From the middle of the posterior
part of the upper surface a thicker portion projects downwards into
the cavity of the _pars neglecta_; it has a narrow, deep notch for the
nerve at about its middle; anteriorly it points towards a sickle-shaped
piece, which is curved inwards. Canals run obliquely downwards and
inwards from the apertures on the superior surface. The membrane is
clear, homogeneous, partly finely striated, and corresponds with the
_membrana tectoria_ of the _pars basilaris_, etc.
(8) The *lagena cochleae* (Figs. 247, 248, and 249 _l_) is an oval
swelling of the membranous labyrinth; it lies close to the sacculus
with its broader end forwards, the narrower directed backwards. By a
large rounded opening at the posterior end it communicates with the
saccule by means of a rounded space common to the _lagena cochleae_ and
the _cochlea_. The _papilla acustica lagenae_ (_pl_) is situated in the
posterior wall of the _lagena_; it is elongated, oval, and supplied by
the _ram. lagenae_. The _papilla_ is covered by a plate-like otolith
formed of numerous rounded particles.
[Illustration: Fig. 250.
The membranous labyrinth of _Rana esculenta_; after Retzius.
I. Transverse section of the anterior ampulla. Magnified 50 times.
II. Piece from under surface of the cupula from the anterior ampulla.
Vérick’s Syst., Obj. VIII. Oc. 3.
III. The macula acustica neglecta, seen from below. Vérick’s Syst.,
Obj. IV, Oc. 3.
IV. Part of wall of the anterior ampulla.
V. Part of the cochlea, the pars basilaris cut longitudinally. Vérick’s
Syst., Obj. I, Oc. 3.
VI. Longitudinal section of the pars basilaris. Vérick’s Syst., Obj. I,
Oc. 3.
VII. The macula ac. neglecta, seen from below. Vérick’s Syst., Obj. IV,
Oc. 3.
VIII. The pars basilaris, seen from behind and the outer side. Vérick’s
Syst., Obj. I, Oc. 3.
IX. Transverse section of the external ampulla. Magnified 175 times.
_apb_ Oval opening into sacculo-cochlear space.
_cr_ Crista acustica.
_cu_ Cupula terminalis.
_dp_ Ductus perilymphaticus.
_mb_ Section of thinner wall of pars basilaris.
_mt_ Tectorial membrane.
_mw_ Thickened membranous wall.
_n_ Nerve-fibres.
_pb_ Pars basilaris.
_pe′_ Area of coarsely granular cells.
_ppb_ Papilla acustica basilaris.
_r_ Epithelium on raphe.
_rb_ Ramulus basilaris.
_rn_ Ramulus neglectus.
_tv_ Tegmentum vasculosum.
]
(9) The *pars basilaris cochleae* (Figs. 247, 248, and 249 _pb_)
is placed on the posterior thickened wall of the saccule and lies
above and behind the _lagena_. It forms a small, oval, pocket-like
protuberance, with the long axis directed from in front and above,
backwards and outwards, its opening being directed forwards and
outwards. The short _ram. basilaris_ passes in from above to supply it.
The walls of this dilatation are thick and stiff, with the exception
of a small portion, the _membrana basilaris_ (Hasse) (_mb_), which
closes the opening into a small dilatation on the anterior inner wall.
The _ramulus basilaris_ (_rb_) divides into, at least, two branches,
and passes close to the _membrana basilaris_ (_mb_), where the
elongated and oval _papilla ac. basilaris_ (Fig. 250 _ppb_) is placed.
The _papilla_ is covered by a _membrana tectoria_ (Fig. 250 _mt_),
which is often found separated from the papilla, probably by the action
of the reagents used. The form of this membrane is peculiar but will
easily be understood from the figure (Fig. 250 _mt_). In structure it
is similar to the corresponding structures found in other parts of the
ear.
[Illustration: Fig. 251.
Preparations from the ear of _Rana esculenta_; after Retzius.
I. Part of the membranous wall seen from the surface. Vérick, Obj. VI,
Oc. 3.
II. Transverse section of the membranous wall. Vérick, Obj. III, Oc. 3.
III. Epithelium from the neighbourhood of the macula ac. rec. utriculi.
Vérick, Obj. III, Oc. 3.
IV. Branched cells from the yellow spot on the floor of the anterior
ampulla. Vérick, Obj. III, Oc. 3.
V. Epithelium from the roof of the anterior ampulla. Vérick, Obj. III,
Oc. 3.
_re_ Epithelium of raphe.
_e_ Pavement epithelium.
_pe_ Protoplasmic cells.
_pg_ Perilymphatic tissue.
]
(10) The *tegmentum vasculosum* (Deiters) (Figs. 245, 248, and 250
_tv_) is an oval, shell-shaped dilatation of the membranous labyrinth;
its long axis is directed from above and in front, downwards and
backwards. The walls of the _tegmentum_ are thin and intimately
attached to the periosteum.
*e.* The *minute structure* of the membranous labyrinth (Figs. 251
252).
(1) The *walls* of the membranous labyrinth have the same general
structure throughout: the walls are usually thicker at the
nerve-terminations, in the ampullae, semicircular canals, _pars
neglecta_, and especially the _pars basilaris_; the wall of the
_tegmentum tympani_ are the thinnest. The walls are transparent,
homogeneous, refractive, and, at places, show a faint striation,
which is, as a rule, not due to the presence of fibres; in parts of
the _recessus utriculi_, and in the outer wall of the _saccule_,
especially near the _tegmentum vasculosum_, more or less distinct
fibres can be made out. Sections of the wall show spindle-shaped
cells, with the processes usually arranged parallel to the surfaces;
seen from the surface, the cells are seen to branch in all directions
(Fig. 251 I, II). In the thinner parts of the walls the cells are few
or altogether absent. The outer surface of the membranous labyrinth is
uneven, in consequence of the attachment of the perilymphatic network.
Blood-vessels are also attached to the outer surface, and pierce the
wall, especially near the nerve-terminations.
The whole of the inner surface is lined with a layer of polygonal,
tesselated epithelium-cells. The size and height of the epithelium
varies in different parts. On the outer wall of the saccule the
cells are large, but on the inner wall small; they are also large in
the semicircular canals, except on a small raphe on the inner and
outer side, where they are smaller but higher (Fig. 251 _re_); in
the ampullae the cells are large, except on the roof. In the utricle
and _sinus superior_ they are also moderately large. In addition to
the places mentioned, a smaller epithelium is found on the floors
of the ampullae, in the _recessus utriculi_, and near all the
nerve-terminations and on the sides of the ampullar septa. Surrounding
the nerve-terminations of the _macula rec. utriculi_, _macula
sacculi_, and _papilla lagenae_ are found narrow, branched, yellowish
cells (Fig. 251 _pe_) with spindle-shaped nuclei. Cells of a third
kind, first described by Deiters, Hasse, and Kuhn, in the _tegmentum
vasculosum_, and in the ampullae by Hasse and Kuhn, are also found
in the utricle. They contain a yellowish pigment, and are collected
into two sharply differentiated groups in each ampulla (Hasse has one
placed before and one behind the septum on the floor). The cells are
cylindrical, the upper parts striated, the lower narrower, and the
bases again widened to a polygonal, more homogeneous plate, which is
fixed to the wall. On the _tegmentum vasculosum_ the corresponding
cells are not so high.
(2) The *nerve-terminations*. The larger branches of the auditory
nerve contain medullated fibres of various dimensions and bipolar,
spindle-shaped ganglion-cells. The nerves pierce the walls obliquely
or vertically, and retain their medullary sheaths until near their
final distribution. On each of the nerve-terminations is found
nerve-epithelium, which varies in height in different parts. In the
_crista acustica_ it measures 0.075 mm. in height in the middle part,
0.06 mm. at the sides; on the _macula rec. utriculi_ 0.09 mm., on the
_macula sacculi_ 0.075 mm., on the _papilla lagenae_ 0.06 mm., on the
_papilla part. basil._ 0.045 mm., on the _macula neglecta_ 0.075 mm.
The epithelium is of two kinds, hair-cells and sustentacular cells.
[Illustration: Fig. 252.
The nerve-terminations in the membranous labyrinth of _Rana esculenta_;
after Retzius.
I. Vertical section through the crista acustica of the anterior
ampulla. Vérick’s Syst., Obj. III, Oc. 3.
II. Vertical section through the macula ac. recessus utriculi. Vérick’s
Syst., Obj. VIII, Oc. 3.
III. Three isolated hair-cells from the crista ac. of the anterior
ampulla. Vérick’s Syst., Obj. VIII, Oc. 3.
IV. Two isolated sustentacular cells from the crista ac. of the
anterior ampulla. Vérick’s Syst., Obj. VIII, Oc. 3.
_cr_ Crista acustica.
_cu_ Cupula terminalis.
_fz_ Sustentacular cells.
_h_ Hairs of hair-cells.
_hz_ Hair-cells.
_n_ Nerve-fibres.
]
α. The hair-cells (Fig. 252 _hz_) have, on the whole, elongated,
flask-like forms, but are not all of the same length (0.024–0.04 mm.).
The free ends of the cells are rounded, flattened, and yellowish,
and each bears a stiff cilium, which is fixed by a broad base to the
cell, and thins out towards its free end: the cilia vary in length; in
the ampullae their greatest length is 0.13 mm., on the _macula rec.
utriculi_ 0.011 mm., and on the _papilla lagenae_ 0.017 mm. The cells
are granular, possess rounded oval nuclei, and are fixed by a fine,
narrow process (Fig. 252 _hz_), though they usually seem to be rounded
off without possessing a process.
β. The sustentacular cells. Under the hair-cells is a finely granular
substance, possessing numerous rounded oval nuclei, which are placed in
superimposed rows (Fig. 252 _fz_), the deepest row being placed close
together and immediately on the membranous wall. After proper treatment
and isolation these nuclei are seen to belong to narrow, elongated
cells, which rest by a slightly widened base on the wall, and are
continued upwards between the hair-cells to reach the surface of the
epithelium, where their upper processes are again slightly widened.
γ. The nerve-fibres (Fig. 252 _n_) lose their medullary coats, ascend
towards the epithelium, and frequently divide to form two unequal
branches, which ascend to the level of the hair-cells, and curve so
as to course horizontally as extremely fine varicose fibrillae; these
frequently form a network, of which the exact method of termination
has not been made out. In some cases a fine fibril may be traced to
the base of a hair-cell, but a direct continuation of the one into the
other has not yet been traced.
VI. THE EYE.
(Re-written by the translator.)
The organ of sight, the eyeball (_bulbus oculi_), together with its
appendages (_tutamina oculi_), will be described in this chapter.
A. The Eye is flattened on the outer surface, more convex on the inner
or deeper surface. Its principal axis is directed from behind, forwards
and outwards.
The outer transparent portion of the eyeball is the cornea, which forms
the outer boundary of the anterior chamber. The larger, white, opaque,
and inner portion is the sclerotic coat, which, together with two
deeper tunics, the choroid coat and the retina, enclose the posterior
chamber of the eye. The pigmented ring placed behind the cornea is
the iris, and the aperture it encloses the pupil. The lens is placed
immediately behind the iris. On the inner side the optic nerve pierces
the sclerotic to enter the eyeball.
*a.* The *sclerotic coat* (_sclerotica s. sclera_) forms about
three-fourths of the surface of the eyeball; posteriorly it is pierced
by the optic nerve at a point (_porus opticus_) nearer the temporal
side than the nasal. The sclerotic coat consists of fibrous tissue
externally, with a layer of hyaline cartilage internally (Helfreich).
The fibrous layer is formed of bundles of parallel fibres, which cross
each other, chiefly at right angles (Hoffmann). The cartilaginous layer
ends just behind the line of insertion of the extrinsic muscle of
the eye, and is thickest at the point of entrance of the optic nerve
(Helfreich).
[Illustration: Fig. 253.
Endothelium from the inner surface of the sclerotic coat; after
Hoffmann.
]
The sclerotic coat is rich in nerve-fibres, which form a close network;
the fibres, however, do not unite but form the meshes of the network by
simply crossing each at acute angles.
The deeper surface of the sclerotic coat is lined with a layer of large
endothelial cells (Hoffmann), (Fig. 253), which form the outer wall of
the capsule of Tenon.
*b.* The *cornea* and the *anterior chamber*. The cornea forms about
one-fourth of the surface of the eyeball and is directly continuous
with the sclerotic. In it five layers can be distinguished: a layer of
stratified epithelium or conjunctiva, an anterior hyaline membrane, the
true corneal substance, a posterior hyaline membrane, and a layer of
endothelium.
(1) The *corneal epithelium* is a layer of stratified epithelium
covering the superficial surface of the cornea. The superficial layer
forms a beautiful mosaic of polygonal cells; the middle layers are
polygonal in all sections, while the deepest layer is more or less
columnar. Except in the most superficial layer, all the cells have
serrated surfaces. Smaller cells possessing each two nuclei are also
found between the columnar cells, and are evidently cells in process of
division; according to Waldeyer, cell-proliferation may also take place
in the middle layers.
The basal or deeper portions of the columnar cells possess a clear
border, which reminds one of the hyaline border found on the free
border of columnar epithelium in other parts. The cells are here so
closely applied to one another that these borders have the appearance
of a continuous, highly refracting membrane (Rollett); according to
Henle, the border consists of a network of very fine processes from the
cells above.
(2) The *true corneal substance*, and (3) the *anterior hyaline
membrane*. The corneal substance consists of flat bundles of fibres
arranged in laminae, with cement-substance and connective-tissue
corpuscles interposed. The fibrils are extremely fine (0·0001 mm.,
Engelmann), and bound together into bundles by cement-substance. The
bundles of the laminae are arranged at various angles, though many are
placed at right angles to each other (Waldeyer).
Between the laminae are flattened spaces, which seen in section are
spindle-shaped. By proper treatment they are seen to be irregular,
branched spaces, which communicate by fine canals and form part of the
Recklinghausen-canals or lymph-system. These spaces contain branched,
connective-tissue corpuscles (Toynbee), and a colourless fluid.
The corpuscles (Fig. 254 _e_) do not fill the spaces which they occupy.
They possess large nuclei, surrounded by granular protoplasm.
[Illustration: Fig. 254.
Preparation from cornea of _Rana esculenta_; after Klein, Hartnack’s
Syst., Obj. VII, Oc. 3.
_a_ Nerve of first order.
_b_ Nerve of second order.
_c_ Nerve of third order.
_d_ Nerve of fourth order.
_e_ Corneal corpuscles.
]
The canals by which these spaces communicate (‘Saftcanälchen’ of
Recklinghausen) lie, in general, parallel to the surfaces of the
cornea, and communicate by joining at acute angles or by short
transverse branches. According to Lavdowsky, these canals have a
distinct lining membrane.
The anterior hyaline[87] layer (Bowman’s or Reichert’s lamella) is not
so well seen in the frog as in some higher animals; it is simply a
portion of the corneal substance, of somewhat denser structure than the
rest, into which it passes by a gradual transition.
[Footnote 87: Tamanscheff and Schweigger-Seidel consider the anterior
and posterior hyaline membranes to be composed of fine fibrils.]
(4) The *posterior hyaline membrane* (Descemet’s membrane) is a highly
elastic, very transparent layer, placed behind the true corneal
substance; in the frog some few bundles of fibres belonging to the
true corneal substance appear to pass into the posterior hyaline
layer, although they cannot be traced further through its substance.
The structure of the membrane is, in consequence of its transparency,
unknown, though the above observation seems to point to a fibrillar
origin.
(5) The *corneal endothelium* is a single layer of polygonal cells of
0·02 mm. diameter. The cells possess the power of altering their shape
when stimulated (Klebs).
[Illustration: Fig. 255.
Preparation from cornea of _Rana esculenta_; after Klein. Hartnack’s
Syst., Obj. X immers., Oc. 3.
_a_ Endothelial cells.
_b_ Nuclei of endothelial cells.
_c_ Nerves of third order in the tissue of the cornea propria.
_d_ Nerves of the fourth order.
]
(6) The *nerves* of the cornea are derived from the _ramus ophthalmica
trigemini_; they pierce the sclerotic coat in front of the sclerotic
cartilage and then course towards the cornea, at the margin of which
they form a coarse network of medullated fibres. From this about thirty
nerves pass towards the cornea, which they enter, and then very quickly
lose the main part of their medullary sheaths. According to Wolff, a
portion of the nerves retain their medullary sheaths, or in some cases
appear to regain it after having lost it.
The nerves passing from the plexus (nerves of the first order, Klein)
give off smaller branches, which for a short distance have a serpentine
or rectilinear course. By a few anastomoses they form a loose plexus
(nerves of the second order, Klein). After a longer or shorter course
they give off numerous lateral fibres, or terminate in several such
fibres arising at one point (nerves of the third order, Klein). These
are distinguished by their size, varying only within small limits,
and by the possession of more or less regularly placed varicosities;
the clearer portions are longitudinally striated as though made up of
fibrillae; they have a nearly rectilinear course, and, after a longer
or shorter course, turn into a direction which is at right angles to
the former one; lastly, they remain for long distances unbranched.
These nerves are connected one with another by cross fibres running at
right angles to them, and in this way a rectangular trellis-work is
formed.
The fibrils (nerves of the fourth order) given off by these nerves
form networks around the connective-tissue corpuscles, but no direct
connection between nerve and corpuscle has been traced; they always
appear to lie on that surface of the corneal corpuscle which is
directed towards the superficial surface of the cornea (Klein). In
the endothelium covering the membrane of Descemet these fibrils can
be traced coursing along the margins of the cells (Fig. 255 _d_), and
sometimes undergoing dichotomous division (Klein).
Almost all observers have described these fibrils as possessing
varicosities; Hulke, and more recently Wolf, however, deny their
presence. Lavdowsky traces nerve-fibrils to the nuclei of the
connective-tissue corpuscles.
(7) The *anterior chamber* is the space between the cornea and the
iris, and is filled with a watery fluid, the aqueous humour. At
the circumference of the chamber are a number of spaces (spaces of
Fontana), formed by interruptions in the tissue between the posterior
surface of the cornea and the iris; the result is that bands or
trabeculae (_ligamentum pectinatum iridis_) pass from the one structure
to the other, and between these are the spaces of Fontana.
According to Angelucci these trabeculae are of three kinds: trabeculae
passing from the cornea to the iris, formed of connective-tissue;
trabeculae from the cornea to the ciliary processes, which contain
elastic tissue; trabeculae from the interstitial connective-tissue of
the ciliary muscle to the cornea, and formed almost entirely of elastic
tissue.
At the junction of the cornea and sclerotic, and just in front of
the spaces of Fontana, is a larger and similar space, which may be
traced round the whole circumference of the cornea; this, the canal of
Schlemm (_Sinus circularis iridis_), is held to be a venous plexus by
some observers (Angelucci, and others), according to others it is a
lymphatic space in connection with the anterior chamber (Schwalbe, and
others). It is certain that the vessels can be very easily injected
from the anterior chamber, although a direct communication has not yet
been seen.
*c.* The *choroid coat* and the *iris* (_tunica choroidea et iris_,
_tunica vasculosa_).
[Illustration: Fig. 256.
The vessels of the choroid and iris; after Hans Virchow.
I. The two roots of the V. bulbi superior. Magnified 10 times.
II. Vessels of the iris. Magnified 9 times.
III. Origin of the ventral vein.
IV. Schema of the choroid vessels; seen from the proximal pole.
V. Transverse section through the choroid at the equator.
VI. The origin of the choroid arteries from the ophthalmic artery.
The greater part of the sclerotic has been removed.
Left eye twice natural size.
A. From the proximal pole. B. From the temporal side.
VII. Part of a choroidal artery attached to the choriocapillaris.
Magnified 10 times.
VIII. A portion of the choriocapillaris, more highly magnified.
IX. The V. ophthalmica and V. bulbi superior on the sclerotic of
the right eye.
A. Seen from proximal pole. B. Seen from above.
Twice natural size.
_A_ Art. ophthalmica.
_A′_ Art. choroidea.
_An_ R. nasalis of the ophthalmic artery.
_At_ R. temporalis of the ophthalmic artery.
_ch_ Area of membrana choriocapillaris.
_Le_ Outer pigmented layer of choroid.
_Li_ Inner pigmented layer of choroid.
_N_ Optic nerve.
_r_ Vasa recta.
_r′_ Transitional part between choriocapillaris and ventral whorl.
_r″_ Transitional part between choriocapillaris and upper whorl.
_R_ Branches of the circulus iridis major.
_Rd_ Distal root of vein of under surface of eye.
_Rd′_ Distal root of nasal vein.
_Rd″_ Proximal root of nasal vein.
_Rp′_ Nasal root of ventral vein.
_Rp″_ Temporal root of ventral vein.
_Vbs_ V. bulbi superior.
_Vh_ V. hyaloidea.
_Vo_ V. ophthalmica.
_Vp._ Proximal root of vein of under surface of eye.
_Vs′_ Nasal root of V. bulbi superior.
_Vs″_ Temporal root of V. bulbi superior.
]
*1.* The *choroid coat* lines the deeper surface of the sclerotic coat,
but is also prolonged under the cornea to form the iris. The choroid
is firmly attached to the sclerotic in two positions, at the point
of entrance of the optic nerve, and at the line of junction of the
sclerotic and the cornea. Its external surface is closely applied to
the deeper surface of the sclerotic, from which it is only separated
by a very narrow serous cavity (supra-choroidal space), and to which
it is attached by numerous vessels and nerves. The deep surface of the
choroid is covered by the retina, to which it is closely attached,
except at the ora serrata, the attachment being especially intimate at
the _processus ciliares_.
The choroid coat consists of a fibrous layer containing corpuscles
and traversed by a very rich vascular anastomosis. The corpuscles
of this layer are deeply pigmented, in some cases to such an extent
that the oval nucleus cannot be seen; the fibrous tissue is also
pigmented, and has consequently a brownish tinge. That portion of the
layer immediately below the sclerotic is termed the _lamina fusca_
or _suprachoroidea_, the vessels on the deeper surface forming the
_membrana choriocapillaris_. This again is lined on its deeper surface
by a hyaline membrane.
α. The arteries (Fig. 256 VI; VII, VIII) supplying this coat are two
branches of the _arteria ophthalmica_; these form a capillary network
(Fig. 256 VII) resembling the corresponding structure found in mammals.
The meshes have approximately the same size, while the capillaries
themselves vary considerably in size. This network is, however, only
complete on the nasal, temporal, and proximal part of the upper
surfaces. Towards the _corpus ciliare_ the meshes become wider and
elongated; the capillaries then unite at acute angles parallel with
the longitudinal axis of the eye. The network (_choriocapillaris_)
exists in a simple layer within the two arteries which form it, and
superficial to the veins (Virchow).
β. The veins of the choroid (Fig. 256 III, IV, IX) are (1) a vein which
unites at the lowest point of the equator of the eye with the _V.
hyaloidea_ to form (2) the _V. ophthalmica_, two small branches of the
_V. bulbi superior_, which unite outside the sclerotic, and (3) the
_vasa recta_.
(1) The larger vein arises from the greater part of the under surface
of the eye; it gives off branches to each side, which radiate to form
a ‘whorl’ or star-shaped capillary anastomosis (Fig. 256 III), the two
halves of which have no connection. A proximal and a distal root can be
distinguished in the anastomosis; the distal lies towards the _corpus
ciliare_, and occupies exactly one-fourth of the circumference of the
choroid at its junction with the _corpus ciliare_.
(2) The two branches of the _V. bulbi superior_ lie alongside the
_corpus ciliare_ on the upper surface, and each occupies one-fourth of
the circumference; they form a similar though simpler figure (Fig. 256
I) to the foregoing, each forming one half.
(3) The _vasa recta_ are numerous parallel vessels which arise in the
iris, and coursing centrally empty themselves into the branches of the
_V. bulbi superior_ on the superior surface, and into the branches of
the venous capillaries on the inferior surface.
*2.* The *iris* is covered anteriorly by a layer of endothelium,
continuous with that covering the posterior surface of the cornea, and
of similar character. The border of the pupil (_margo pupillaris_)
is of a golden colour, outside this bright ring to its outer margin
(_margo ciliaris_) the iris is black; the golden colour is due to the
presence of cells containing a pale yellow pigment; the nuclei of
these cells are round and granular; the cells themselves have rounded
outlines (Hoffmann). The black portion of the iris contains more
irregular, spindle-shaped cells, with round nuclei, which are hidden by
a dense mass of pigment-granules (Iwanoff and Hoffmann).
The true substance of the iris consists of muscle, nerves,
blood-vessels, and a connective-tissue stroma, but on the posterior
surface is another layer of black, pigmented cells, and this is again
covered with a hyaline membrane, in which, however, a fibrous structure
may be made out (Koganeï).
The muscle-fibres are long, spindle-cells, which are abruptly swollen
in the middle, where the nuclei are situated; the nucleus is oval,
0.009–0.0012 mm. in length, 0.0025 mm. broad, and occupies nearly the
whole of the swollen part of the cell (Hoffmann, Grünhagen).
According to Koganeï the iris possesses a _M. constrictor iridis_
(_l. c._ Berlin Sitzungsber.), but no _M. dilatator iridis_; in a
former publication (_l. c._ Arch. mik. Anat.) he was unable to find
any muscular fibre, and holds the muscle-fibres of Grünhagen to be
connective-tissue elements.
The stroma consists of delicate connective-tissue fibrils, enclosing a
very large number of pigmented, branched cells.
α. The *arteries* of the iris (Fig. 256 II) arise from an arch (see
Vessels of Eye) formed by the _A. ophthalmica_ in the _corpus ciliare_.
It commences between the ventral and temporal surfaces by two branches:
one courses along the temporal border, the other along the nasal,
to meet each other on the nasal surface; the former courses through
one-third, the latter embraces two-thirds of the circumference at the
iris.
The temporal artery courses along the ciliary border during the first
third of its course, it then gradually approaches the border of the
pupil; the nasal artery runs at once towards the pupil. On the nasal
border of the pupil they anastomose by their branches, and so form a
_circulus iridis major_.
Except near their termination, no small vessels arise from this
arterial circle; in Fig. 256 II, for example, only five larger branches
are given off, three from the temporal side and two from the nasal.
The five large branches run towards the circumferential border of the
iris and break up into numerous vessels, which form a very irregular
and open network. From this network arise the _vasa recta_ already
described.
*d.* The *lens* is almost spherical, and is composed of cellular
elements enclosed in a capsule (_capsula lentis_).
The capsule is a homogeneous, transparent, structureless, and highly
elastic membrane. The deeper surface of the anterior capsule is lined
with a simple layer of regular nucleated six-sided epithelial cells.
The lens itself consists of long, flat fibres; seen from the surface
these are broad, narrow edge-wise, and in section six-sided prisms.
Those lying parallel to the anterior and posterior surfaces are broad
and thicker, those towards the border are narrower. These cells are
striated, both longitudinally and transversely (Arnold). The cells near
the margin, however, have no transverse striation (Hoffmann). The cells
of the central parts form a much closer and firmer structure than those
at the periphery (Arnold). The peripheral cells are nucleated, and
sometimes even possess two nuclei to one cell; the central cells have
no nuclei (Arnold).
The cells are held together by a cement-substance and by their serrated
surfaces; the serrations are the cause of the transverse striations.
The fibres of the lens have a simple arrangement: commencing at the
middle point or pole of one surface they pass over the equator to the
opposite pole; consequently the long borders of adjacent cells are in
juxtaposition, and their pointed extremities meet at points in the axis
of the lens (Hoffmann).
Ritter has described short, nucleated cells in the centre of the lens;
these are held by Babuchin to be cells which have been arrested in
their development.
[Illustration: Fig. 257.
Fibres from the lens of the frog; after Hoffmann. Magnified 700 times.
]
*e.* The *retina* is the innermost coat of the eye; in the recent
state it is pale, soft, and smooth. The structures composing it are
arranged in ten layers; from the deeper surface towards the choroid
these are: the internal limiting membrane, the optic-fibre layer, the
ganglion layer, the inner molecular layer, the inner nuclear layer, the
outer molecular layer, the outer nuclear layer, the external limiting
membrane, the layer of rods and cones, and the pigment layer.
These layers are held together by connective-tissue elements.
(1) The *internal limiting membrane* (_Membrana limitans interna_) will
be described together with the connective-tissue elements (10).
(2) The *optic-fibre layer* is formed by the fibres of the optic
nerve. The nerve-fibres in their course towards the eye are possessed
of medullary sheaths, but on piercing the sclerotic these sheaths are
lost. The fibres are now pale, non-medullated, and of very varying
thickness. In the mass of fibres nothing can be seen except an
extremely fine fibrillation and very fine varicosities; the latter,
however, appear to be artificial productions (Hoffmann). This layer
of fibres extends over the inner surface of the retina, and gradually
thins from the point of entrance of the optic nerve to the limits of
the retina.
(3) The *ganglion-layer* lies immediately without the nerve-fibre layer
(Fig. 258 _b_). The ganglion-cells are small and usually pear-shaped.
The cells possess large nuclei, round which is a thin layer of very
granular protoplasm. The cells have inner and outer processes; the
inner pass into the nerve-fibre layer, the outer into the inner
molecular layer in more or less radiating directions. Manz claims to
have traced a direct connection between the inner processes and the
fibres of the nerve-fibre layer.
Each ganglion-cell, whatever its shape or size, has only one inner
process, which is easily distinguished from the outer process by its
being more glistening, by the possession of varicosities, and because
this process never branches.
The outer processes are single (Schwalbe) or rarely double (Hoffmann),
and have as a rule a direction at right angles to the inner processes.
Each outer process is finely granular, which suggests rather a
prolongation of the cell-substance than a true process. Frequently they
are branched, sometimes forming two equal sized processes, which give
off finer twigs; at other times they appear to pass through the whole
of the inner molecular layer without undergoing division (Schwalbe).
The processes do not inosculate (Santi Sirena).
[Illustration: Fig. 258.
Vertical section through retina of frog; after Hoffmann. Magnified 500
times.
_a_ Internal limiting membrane.
_b_ Ganglion-cell layer.
_c_ Internal molecular layer.
_d_ Internal nuclear layer.
_e_ External molecular layer.
_f_ External nuclear layer.
_g_ Layer of rods and cones.
_h_ Pigmented epithelium layer.
1. Inner segments of rods and cones.
2. Outer segments of rods and cones.
3. Outer transparent segments of pigmented epithelium.
]
(4) The *inner molecular layer* (Fig. 258 _c_) is 0·07–0·08 mm. thick
(Hoffmann), and consists of a finely granular mass together with the
outer processes of the ganglion-layer, and connective-tissue elements.
The granular matter consists of an extremely fine network or reticulum,
through which numerous fine fibres course (Schultze, Kölliker, Manz,
Heinemann, and others); according to Schultze the supposed molecules
or granules of others (Henle, Merkel, and Retzius) are simply the
fine meshes of this reticulum. The branched, outer processes of the
ganglion-cells form a rich anastomosis in this layer.
(5) The *inner nuclear layer* (Fig. 258 _d_) contains parts of two
kinds of cellular elements; these are radial nerve-fibres with
large nuclei, and connective-tissue elements (see below, par. 10).
The nerve-fibres are easily distinguished by their spindle-shaped
varicosities; both cellular elements possess large oval nuclei. The
bodies of the cells surrounding the nerve nuclei are almost filled by
the nuclei, which have sharply-defined, rounded nucleoli. The fibres
to which these cells are attached may be distinguished as inner and
outer processes; the inner process is fine, irregularly varicose, and
unbranched; the outer process is thicker, finely granular, and is not
varicose (Schwalbe). At the margin of the outer molecular layer the
outer processes divide, usually into two branches, and at an acute
angle to each other, though sometimes at a right angle. The further
course of these branches in the outer molecular layer is unknown.
(6) The *outer molecular layer* (Fig. 258 _e_) corresponds in general
with the inner molecular layer as regards its structure; it is,
however, much thinner.
(7 and 9) The *outer nuclear layer* and the *layer of rods and cones*
(Figs. 258 _f_, _g_, 259). The rods and cones are intimately connected
with the elements of the outer nuclear layer, hence the two layers are
best described together.
The rods (_bacilli_) have two parts or limbs, an outer and an inner,
which differ in structure, and in chemical and physical characters. The
outer part is highly refractive, the inner more homogeneous and less
refractive, the two parts being sharply differentiated from one another.
The outer part is also weakly doubly refracting, the inner has no
trace of this property. The rods are 0·05–0·06 mm. in length, of
which 0·035–0·04 mm. belongs to the inner limb. The outer end of the
outer limb is more or less rounded; the whole has a longitudinal
striation (Schultze), due to its being composed of rounded fibrils,
about twenty-four to each rod (Hensen). The fibrils are sharply
differentiated from each other and have a slightly spiral course; when
seen in transverse section these outer limbs do not appear to be round
(Schultze), although others hold them to be perfectly rounded (Hoffmann
and others), and that the loss of the cylindrical form is due to the
methods of treatment. According to Merkel the longitudinal striation
is caused by a canalisation of the outer limb, which according to him
encloses the processes of the pigmented epithelial layer; he is also
of opinion that the spiral appearance is an artificial product. In the
latter opinion he is probably wrong, as perfectly fresh rods examined
in aqueous humour show the same spiral appearance (Hoffmann): against
the canalisation view others observe that the longitudinal striation is
most distinct near the inner limit of the outer limb, and that it is
impossible to conceive that the processes of the pigment-cells should
terminate with such extremely regular ends (Hoffmann).
[Illustration: Fig. 259.
Various preparations from the eye of the frog: chiefly from the retina.
1. Rod from retina in aqueous humour, showing spiral striation.
2. Three rods and one cone after treatment with osmic acid.
3, 4, 5. Rods examined in recent state.
6, 7. Inner segments of two rods after treatment with osmic acid.
_a_ Outer limb.
_b_ Inner limb.
_c_ Lenticular body.
_d_ Nucleus of outer nuclear layer.
_e_ External limiting membrane.
8. Nuclear body from inner nuclear layer.
9. Twin-cone.
10. Sustentacular fibre of retina.
11. Surface view of pigmented epithelium of retina.
12, 13. Isolated pigmented cells of retina.
14. Four pigmented cells, rods and cones, external limiting
membrane, and part of outer nuclear layer attached.
15. Two pigmented cells; each showing three attached rods.
16. Muscle-fibre from the iris.
Figs. 1, 2, 3, 4, 5, 6, 7, 8, 9 are magnified 500 times. Fig. 10, 300
times. Fig. 16, 400 times. All are copied from Hoffmann’s figures.
Figs. 12, 13, 14, 15 are copied from Morano’s figures; Hartnack, Oc.
II, Obj. 9.
]
In the central part of the inner end of the outer limb is seen a dark
point when the structures are examined in transverse section (Ritter,
Manz, Schiess, Schultze, and others). The cause of this is not clearly
understood; some hold it to be a fibre (Ritter’s fibres), others hold
it to be an artificial product (Hensen).
After treatment with certain reagents the outer limbs show a transverse
striation, which is probably produced by the action of these reagents
on the sheath of the outer limbs; that a sheath is present is proved by
its possession of a different refractive index (Zenker, Schultze) to
the rest of the outer limb, and this transverse striation is not seen
until the whole organ has undergone considerable _post-mortem_ changes
(Hoffmann). Should this change be allowed to proceed a stage further,
the outer limbs of the rods split transversely and form small discs
from 0·0005–0·00055 mm. thick; this takes place in the outer limb only.
The inner segments of the rods (Figs. 258, 259) are short
(0·020–0·022 mm.) and of the same thickness as the outer limbs. When
perfectly fresh they appear homogeneous; very quickly changes commence,
which are probably due to coagulation. A plano-convex figure (Fig. 259)
is then seen at the outer portion of the segment (lens-shaped figure
of Schultze); with staining reagents it gives the same reactions as
the outer segment of the rods. The rest of this segment forms a short
cylinder, which probably has no distinct sheath (Hoffmann, Merkel);
some observers are inclined to think that a sheath exists (Landolt,
Schwalbe).
The outer segments of the rods are of two chief sizes (Schwalbe). Those
of the one kind are large; the second variety occurs less frequently,
and the segments are shorter, measuring only 0·002 to 0·0025 mm. The
inner segment is a long, thread-like process, except where it is
swollen to enclose the lens-shaped body.
The rods are much more numerous than the cones, except at one small
spot (_macula lutea_) on the posterior surface of the retina, where
only cones are found (Krause).
The cones (_coni_) have each two segments like the rods (Figs. 258,
259). The outer segments are short (4–5 µ), they are slightly conical
and terminate externally in a blunt point; they possess a longitudinal
striation (Schultze), and very easily break up transversely into small
discs, which, however, do not separate so completely as in the case of
the rods, in consequence of the presence of a sheath continuous with a
sheath on the inner segment.
The inner segments (Figs. 258, 259) have convex sides and measure
12–14 µ; like the corresponding parts of the rods they possess
lens-shaped bodies at their junction with the outer segments, but the
bodies differ in shape, being bi-convex or rather oval in form. The
inner segments are enclosed in a delicate sheath continuous with that
of the outer segments.
In some cases two cones are united to form a twin-cone; in such cases
the one is always larger than the other (Fig. 259 9), and has
several peculiarities which distinguish it from the smaller.
The smaller or secondary member of a twin-cone is longer, and possesses
a lens-shaped body which is plano-convex. The larger or principal
member of a twin-cone is shorter, has a plano-convex body, but also an
oval, homogeneous, glistening body, which is directly attached to the
plano-convex body. The shape of the two members is also different.
The *outer nuclear layer* (Fig. 258 _f_) is 14–16 µ thick; the nuclei
lie in two layers. The nuclei belonging to rods and cones have the
same characters, each nucleus being a large, oval, hyaline body,
and enclosing a bright nucleolus. Each nucleus is surrounded by an
extremely thin layer of finely granular matter. The inner processes of
the nuclear bodies both of the rods and the cones extend to the outer
molecular layer, are there dilated and serrated, where they become
attached to the outer molecular layer (Schultze, Hoffmann). In some
cases, however, the inner process of the nuclear bodies, belonging to
the rods, forms only a short fine fibre.
In the case of twin-cones the corresponding parts in the outer nuclear
layer possess two nuclei (Schultze).
(8) The *pigment layer* (Figs. 258 _h_, and 259 11, 12, 13, 14, 15)
is not intimately attached to the rest of the retina. It consists
of cylindrical cells in which two parts or segments are sharply
differentiated; the external part, directed towards the choroid
coat, is of pale, or colourless granular protoplasm, and occupies
one-third of the length of the cell; this part encloses a large, round,
nucleolated nucleus. This colourless segment of the cell also includes
one or two bright yellow, fat globules (Morano). Seen from the surface
the cells are hexagonal (Fig. 259 11). The remaining two-thirds of the
cells consists of a brush formed of numerous fine pigmented processes;
the ultimate terminations of the processes, which lie parallel to each
other, are frequently unpigmented; each cell possesses thirty to forty
such processes (Morano).
The processes extend between the rods and cones as far as the external
limiting membrane (Figs. 258, 259), or sometimes a little further
(Merkel, Morano, Hoffmann). The processes from one pigment-cell
surround a number of rods and cones; according to Morano twelve to
fifteen rods and cones may be encased or surrounded by the processes of
a single cell.
The thickness of this layer varies from 60–70 µ; the nuclei of the
cells have a diameter of 10–12 µ, the width of a single cell is from
20–25 µ (Hoffmann).
(10) The *connective-tissue elements* of the retina and the *external*
and *internal limiting membranes*. The elements of the retina are
supported by connective-tissue elements or sustentacular cells, which
have a radial arrangement, and which form the two limiting membranes
(Müller).
Each sustentacular cell (Fig. 259 10) has two segments, an inner
and an outer, the boundary between these lying in the inner nuclear
layer, and being marked by the presence of a large oval nucleus. The
inner segment of each cell terminates internally in a wide ‘foot’
or base, or may form several such after having undergone division
(Schultze): these bases together form a transparent, thin membrane, the
internal limiting membrane (_membrana limitans interna_).
Within the ganglion-layer these cells possess peculiar appendages,
which fit round the ganglion-cells and support them (Schwalbe).
The outer segments of the sustentacular cells extend into the outer
molecular layer, and then break up into irregular processes which
extend radially to the external limiting membrane, and which they
probably form. The external limiting membrane (_membrana limitans
externa_) is therefore a membrane corresponding to the internal
limiting membrane, and formed by the flattened ends of the processes
belonging to the sustentacular cells.
The sustentacular cells have a distinct, resistant cell-wall
(Schwalbe); the cell-contents are a finely granular protoplasm, and a
large oval, nucleated nucleus placed in the inner nuclear layer.
*f.* The *ciliary processes* have the same structure as the rest of the
choroid coat: the vessels form more or less longitudinal meshes and are
more irregular than in the rest of the choroid.
*g.* The *posterior chamber* and *vitreous body* (Fig. 260). The
vitreous humour occupies the greater portion of the cavity of the
eyeball, _i.e._ the posterior chamber. The humour consists of a
mass of cells enclosed in a transparent hyaloid membrane (_membrana
hyaloidea_), which is in contact with the internal limiting membrane of
the retina.
The cells forming this structure are small, flattened, transparent,
and nucleated (Iwanoff and Virchow); according to the former observer
the cells have contractile powers.
The hyaloid membrane is described as structureless by Schwalbe, as
fibrous by Pappenheim, Bowman, and Fuikbeiner.
The vessels of the vitreous body (Fig. 260) are as follows. The _A.
hyaloidea_ arises at the lowest point of the _corpus ciliare_; it
almost immediately divides into two branches, which form a ring at a
distance of about 0·5 mm. from the lens and lying on the surface of
the vitreous body (Fig. 260 I, II). One, _R. nasalis_, passes to the
nasal side and courses through one-fourth of the circle; the other,
_R. temporalis_, courses through three-fourths of the circle. The
branches are all given off proximally and at right angles to the circle
(Fig. 260 I, II). From the _R. nasalis_ only one branch arises, from
the _R. temporalis_ seven, the first of which corresponds in point of
origin with the branch from the _R. nasalis_. The branches on the nasal
and temporal surfaces of the vitreous body are the shortest.
[Illustration: Fig. 260.
The vessels of the vitreous body; after Hans Virchow.
I. Vessels of the vitreous body; seen from the deeper pole and slightly
from above. Magnified 6 times.
II. Arteries of the vitreous body of the right eye.
_A_ Seen from the proximal pole.
_B_ Seen from the nasal side.
III. Veins of the vitreous body of the left eye.
_A_ Seen from the proximal pole.
_B_ Seen from the nasal side.
_a_ Nasal vein.
_b_ Temporal vein.
_c_ Branch (constant) of temporal vein.
_n_ R. nasalis of the ophthalmic artery.
_t_ R. temporalis of the ophthalmic artery.
_t′_ Termination of the R. temporalis.
_V_ Ventral vein.
]
These branches form a capillary network (Fig. 260 I) with elongated
meshes, formed by the capillaries anastomosing at acute angles. The
capillary network is more dense towards the middle of the proximal
surface than in other parts.
The veins arising from this network are three in number (Fig. 260
III); two of these accompany the arteries from their origin, and
form a somewhat similar circle around the lens, while the third
passes backwards along the ventral surface of the vitreous body to
the _papilla nervi optici_. The nasal vein, however, takes a more
proximal course than the corresponding artery, the branches of which
it crosses; consequently the venous ring is not so perfect as the
arterial. The nasal vein is larger and the temporal vein smaller than
the corresponding arteries.
The ventral vein is formed near the _papilla nervi optici_ by the
union of two smaller branches. The capillary system of these vessels
has the usual structure of capillaries, the cells being united by
cement-substance (Zimmermann).
The blood-vessels of the vitreous body are accompanied by lymphatics;
according to Iwanoff they completely enclose the capillaries: Zimmerman
contradicts this view, as he has been unable to find lymphatics on that
side of the capillaries directed towards the vitreous body.
B. Appendages of the eye.
The appendages of the eye are the eye-muscles (see pp. 55–59), the
eyelids, the Harderian gland, and the lachrymal duct.
*a.* The *eyelids* are two in number, an upper and a lower. The upper
eyelid is intimately attached to the eyeball and follows the movements
of that organ.
The *lower eyelid* (_membrana nictitans_) is much larger than the upper
and has the same functions as the lower eyelid of higher vertebrates.
It forms a transparent covering for the eyeball, and is raised by a
special muscle (see p. 58); functionally it takes the place of both
eyelids of higher vertebrates.
The lower eyelid is a prolongation of the skin, but has only a few
pigment-cells, except at its free margin, and no serous glands. Mucous
glands are found in two or three rows, closely applied to one another,
on the superficial surface of the lid; on the deeper surface they are
wanting. The stroma of the lid, like the cutis, is of connective-tissue.
Nerve-fibres can be traced in all directions through the substance of
the lid, forming a wide-meshed plexus. Around each gland the plexus
becomes finer and by numerous branchings much closer; from the plexus
twigs are given off, which divide to form a number of fibrils traceable
into the epithelial cells of the glands (Openchowski).
The vessels of the lower eyelid have been investigated by Stricker,
(_l. c._); according to him they possess some interesting
peculiarities. Many of these capillaries course within a lymphatic
vessel, in some places the capillary being contracted by a projection
from its inner wall; where this is found the accompanying lymphatic
is correspondingly dilated. Such points are especially met with where
the capillaries branch; in many cases the capillary was contracted
to such an extent that the blood-corpuscles were unable to pass the
obstruction. Stricker further observed in the living tissue that such
constrictions could take place in a part which a short time previously
had been comparatively wide and dilated; further, that many of the
nerves were enclosed in similar lymphatics. Langer, however (_l. c._),
describes the vessels as being accompanied by an irregular network of
small lymphatic vessels.
[Illustration: Fig. 261.
Preparations from the nictitating membrane of _Rana esculenta_ to show
distribution of nerves.
I. Preparation of the nictitating membrane to show nervous supply to a
capillary vessel; after Klein. Hartnack, Oc. III, Obj. 8.
_a_ Capillary vessel.
_b_ Blood-corpuscles.
_c_ and _d_ Non-medullated nerve-fibres.
II. To show distribution of nerves in the epithelium; after Klein.
Hartnack, Oc. IV, Obj. 8.
_a_} Subepithelial
_b_} nerve-fibres.
_c_ Fine fibrils between the deepest epithelial cells.
_d_ Deepest epithelial cells.
]
The distribution of the nerves in the lower eyelid has been described
by Klein. In the epithelium they form a network resembling that found
in the cornea (Fig. 261 II); along the blood-vessels the fine fibrils
form a perivascular network, which supplies fine twigs to the walls
of the vessels (Fig. 261 I). He distinguishes three kinds of pigmented
cells.
*b.* The *Harderian gland* is situated at the inner angle of the eye,
and is pear-shaped in form. It consists of a number of racemose glands
held together by connective-tissue, the whole being enclosed in a
relatively thick and strong capsule of connective-tissue.
The alveoli have a diameter of 0·040–0·060 mm.: they possess a lining
of epithelium and a lumen which varies considerably in size. The
epithelial layer is bounded externally by a membrana propria. The
cells are placed eccentrically, they are cylindrical, and composed of
finely granular protoplasm; each cell contains a pale, rounded nucleus.
The ducts of the alveoli are lined with a single layer of cylindrical
epithelium, the cells of which are usually shorter and narrower than
those of the epithelium of the alveoli; the ducts open into a single
main tube, lined with similar epithelium but strengthened externally by
a layer of connective-tissue. The glands secrete a fluid which moistens
the free surface of the eye.
The Harderian glands are surrounded by a rich capillary anastomosis
which completely invests the alveoli.
*c.* The *lachrymal duct* opens behind and below into the nasal cavity
(see p. 389), anteriorly it can be traced forwards, as a small tube
imbedded in connective-tissue and lying immediately beneath the skin,
to the outer angle of the eye, where it opens by numerous tubules.
The lachrymal duct is lined with ciliated columnar epithelium.
ADDENDA.
HISTOLOGY OF MUSCLE, CARTILAGE, BONE, AND THE CONNECTIVE TISSUES.
LITERATURE.
I. MUSCLE AND NERVE-ENDINGS IN MUSCLE.
*Arnold, J.*, Gewebe der organischen Muskeln. Stricker’s Gewebelehre,
1871. Vol. I, p. 142.
*Arnold, J.*, Ueber die Abscheidung des indigschwefelsauren Natrons
im Muskelgewebe. Virchow’s Arch. Vol. LXXI, p. 1.
*Babuchin*, Ueber den feineren und Ursprung des Axencylinders.
Centralbl. f. med. Wiss. 1868, p. 755.
*Barfurth, D.*, Die Rückbildung des Froschlarvenschwanzes und die
sogenannten Sarkoplasten. Arch. f. mik. Anat. 1887. Vol. XXIX,
p. 35.
*Biedermann, W.*, Zur Lehre vom Bau der quergestreiften Muskelfaser.
Wiener Sitzungsber. 1876. Vol. LXXIV, Pt. III, pp. 49–62.
*v. Biesiadecki, A.*, and *Herzig, A.*, Die verschiedenen Formen
der quergestreiften Muskelfasern. Wiener Sitzungsber. 1859,
Vol. XXXIII, p. 146: and in Moleschott’s Untersuchungen, 1860,
Vol. VI, p. 105.
*du Bois-Reymond, E.*, Ueber facettenförmige Endigung der
Muskelbündel. Berlin. Acad. Monatsber. 1872, pp. 791–814. Abstract
in Centralbl. f. d. med. Wiss. 1873. No. 55, p. 868.
*Bowman.* On the minute structure and movements of voluntary muscle.
Phil. Trans. 1840, p. 457.
*Bremer, L.*, Ueber die Endigungen der markbaltigen und marklosen
Nerven im quergestreiften Muskel. Arch. f. mik. Anat. 1882.
Vol. XXI, p. 165.
*Bremer, L.*, Ueber die Muskelspindeln nebst Bemerkungen über
Structur, Neubildung, und Innervation der quergestreiften
Muskelfaser. Arch. f. mik. Anat. 1883. Vol. XXII, p. 318.
*Calberla, E.*, Studien über die Entwicklung der quergestreiften
Muskeln und Nerven der Amphibien und Reptilien. Arch. f. mik.
Anat. 1875. Vol. XI, p. 442.
*Calberla, E.*, Ueber die Endigungsweise der Nerven in den
quergestreiften Muskeln der Amphibien. Dissert. Freiburg i.
B. 1874; also in Zeitschr. f. d. wiss. Zool. 1874. Vol. XXIV,
pp. 164–178.
*Chittenden, R. H.*, Histochemische Untersuchungen über das Sarkolemm
und einige verwandte Membranen. Untersuch. d. physiol. Instituts
d. Universität Heidelberg. Vol. III.
*Cohnheim, J.*, Ueber die Endigung der Muskelnerven. Centralbl. f. d.
med. Wiss. 1863, p. 865.
*Eberth, C. J.*, Untersuchungen über die normale und pathologische
Leber. Virchow’s Arch. 1864. Vol. XXXIX, p. 74.
*Engelmann, T. W.*, Zur Lehre von der Nervenendigung im Muskel.
Jenaische Zeitschr. 1868. Vol. IV, p. 307.
*Engelmann, T. W.*, Untersuchungen über den Zusammenh. von Nerven u.
Muskelfasern. Leipzig, 1863.
*Engelmann, T. W.*, Microscopische Untersuchungen über die
quergestreifte Muskelsubstanz. Pflüger’s Arch. 1873. Vol. VII,
pp. 33–71, and pp. 155–187.
*Engelmann, T. W.*, Ueber die Endigung der motorischen Nerven in den
quergestreiften Muskeln der Wirbelthiere. Centralbl. f. med. Wiss.
1863, p. 289.
*Ewald, A.*, Ueber die Endigung der motorischen Nerven in den
quergestreiften Muskeln. Pflüer’s Arch. 1876. Vol. XII, p. 529.
*Ewald, A.*, and *Kühne, W.*, Die Verdauung als histologische
Methode. Heidelb. naturhistor.-med. Verhandl. 1877. Vol. I, p. 451.
*Exner, S.*, Notiz zu der Frage von der Faserverteilung mehrerer
Nerven in einem Muskel. Pflüger’s Arch. 1885. Vol. XXXVI, p. 572.
*Fischer, E.*, Ueber die Endigung der Nerven im quergestreiften
Muskel der Wirbelthiere. Arch. f. mikrosk. Anat. 1877. Vol. XIII,
p. 365.
*Froriep, A.*, Ueber das Sarcolemm und die Muskelkerne. Arch. f.
Anat. u. Physiol. 1878, p. 416.
*Gerlach, J.*, Ueber das Verhalten der Nerven in den quergestreiften
Muskelfäden der Wirbelthiere. Sitzungsb. Erlangen. 1873. Vol. V,
p. 97; Abstract in Centralbl. f. d. med. Wiss. 1874, p. 227.
*Gerlach, J.*, Das Verhältniss der Nerven zu den willkürlichen
Muskeln der Wirbelthiere. Leipzig, 1874.
*Gerlach, J.*, Ueber das Verhältniss der nervösen und contractilen
Substanz des quergestreiften Muskels. Arch. f. mik. Anat. 1877.
Vol. XIII, p. 399.
*Golgi, C.*, Sui Nervi dei Tendini dell’ Uomo e di altri Vertebrati
e di un nuovo Organo Nervoso terminale Musculo-tendineo. Torino.
Estr. dalle Memorie della Reale Acc. di Torino. Series II. 1880,
Vol. XXXII.
*Grützner, P.*, Zur Anatomie und Physiologie der quergestreiften
Muskeln. Recueil Zoolog. Suisse, 1884. Vol. I, pp. 665–684.
*Haycraft, J. B.*, Upon the cause of the striation of voluntary
muscular tissue. Quart. Journ. Micros. Soc. 1881. Vol. XXI, p. 307.
*Hensche*, Ueber die Drüsen und glatten Muskeln in der äusseren Haut
von Rana temporaria. Zeitschr. f. wiss. Zool. 1856. Vol. VII,
p. 273.
*Hensen, V.*, Ueber die Entwicklung des Gewebes und der Nerven im
Schwanze der Froschlarve. Virchow’s Arch. 1864. Vol. XXX, p. 51.
*Jakimovitsch*, Ueber die Regeneration der glatten Muskelfasern.
Centralbl. f. d. med. Wiss. 1879, p. 897.
*Key, A.*, Bidrag till Nervernas ändningsätt i Musklerna.
Förhandlingar vid Skandinaviska Naturforskaemötet i Stockholm,
1863. Abstract in Centralbl. f. d. med. Wiss. 1866, p. 212.
(Muscles of frog’s tongue.)
*Klebs, E.*, Die Nerven der organischen Muskeln. Centralbl. f. d.
med. Wiss. 1863, p. 561.
*Klebs, E.*, Die Nerven der organischen Muskeln. Virchow’s Arch.
1865. Vol. XXXII, pp. 169–198.
*v. Kölliker, A.*, Gewebelehre.
*v. Kölliker, A.*, Einige Bemerkungen über die Endigung der
Hautnerven u. den Bau der Muskeln. Zeitschr. f. wiss. Zool. 1857,
Vol. VIII, p. 311.
*Krause, W.*, Ueber den Bau der quergestreiften Muskelfaser.
Zeitschr. f. rat. Med. Vol. XXIII.
*Krause, W.*, Die Nervenendigungen in den Froschmuskeln. Internat.
Monatschr. 1884. Vol. I, pp. 194–203.
*Krause, W.*, Die motorischen Endplatten, etc. Hannover, 1869.
*Krause, W.*, Ueber die Endigungen der Muskelnerven. Göttinger
Nachrichten. 1863, p. 21.
*Krause, W.*, Ueber die Endigungen der Muskelnerven. Henle and
Pfeufer’s Zeitschr. 1863. Vol. XX, pp. 1–19.
*Kühne, W.*, Untersuchungen über Bewegungen und Veränderungen der
contractilen Substanzen. Arch. f. Anat. n. Phys. 1859, p. 816.
*Kühne, W.*, Die Muskelspindeln. Virchow’s Arch. 1864. Vol. XXVIII,
pp. 528–538.
*Kühne, W.*, Untersuchungen über das Protoplasma und die
Contractilität. Leipzig, 1864.
*Kühne, W.*, Ueber die peripherischen Endorgane der motorischen
Nerven. Leipzig, 1862.
*Kühne, W.*, Zur Lehre von den Endplatten der Nervenhügel. Virchow’s
Arch. 1866. Vol. XXXIV, pp. 412–422.
*Kühne, W.*, Ueber das Verhalten des Muskels zum Nerven. Verhandl. d.
natur-hist.-med. Vereins zu Heidelberg. 1880. Vol. II, p. 227.
*Kühne, W.*, Ueber Nervenendigungen in den Muskeln nach Beobachtungen
von M. B. van Sykel. Abdruk. aus den Verhandl. d. Naturh. med.
Verein zu Heidelberg. 1884. Vol. III, pp. 238–242.
*Kühne, W.*, Wiederlegung der Bemerkung E. du Bois-Reymond’s über
mehrfache. Nervenendigungen einer Muskelfaser. Zeitschr. f. Biol.
1884. Vol. XX, pp. 531–539.
*Kühne, W.*, Ueber die Endigung der Nerven in den Muskeln. Virchow’s
Arch. 1866. Vol. XXVII, pp. 508–533.
*Kühne, W.*, and *Voit, C.*, Neue Untersuchungen über motorische
Nervenendigung. Zeitschr. f. Biologie. Vol. XXXIII.
*Lavdowsky, M.*, Die feinere Struktur und die Nervenendigungen der
Froschharnblase. Arch. f. Anat. u. Physiol. 1872, p. 55.
*Leboucq, H.*, Recherches sur le développement et la terminaison des
nerves chez les larves des Batrachiens. Bull. de l’Acad. de roy.
de Belgique. 1876. Vol. XLI, p. 561.
*Letzerich, L.*, Ueber die Endigungsweise der motorischen Nerven.
Med. Centralz. 1863, No. 37.
*Leydig, F.*, Ueber Tastkörperchen und Muskelstructur. Arch. f. Anat.
u. Physiol. 1856, p. 150.
*Löwit*, Die Nerven der glatten Muskulatur. Sitzungsb. d. Wiener
Acad. 1875. Vol. LXXI, Pt. III, p. 355.
*Marshall, C. F.*, The structure and distribution of striped and
unstriped muscle. Quart. Journ. Micros. Sci. 1887. Vol. XXV.
*Martin, H.*, Sur la structure de la fibre musculaire striée et
sur les analogies de structure et fonction entre les tissus
musculaires et les cellules à bâtonnets (protoplasma strié). Arch.
de physiol. norm. et pathol. 1882, p. 465.
*Mayer, S.*, Die sogenannten Sarkoplasten. Anat. Anzeiger, 1886. No.
9, p. 231.
*Mayer, S.*, Einige Bemerkungen zur Lehre von der Rückbildung der
quergestreiften Muskelfasern. Prager Zeitschr. f. Heilkde. 1887.
Vol. VIII, p. 177.
*Mays, K.*, Histo-physiol. Untersuchungen über die Verbreitung der
Nerven in den Muskeln. Zeitschr. f. Biol. Vol. XX.
*Mays, K.*, Ueber die Nervatur des Musculus rectus abdominis des
Frosches. Heidelberg, 1886.
*Melland, B.*, A simplified view of the histology of the striped
muscle-fibre. Quart. Journ. Micros. Sci. 1885. Vol. XXV, p. 371.
*Merkel, F.*, Der quergestreifte Muskel. Arch. f. mik. Anat. 1873.
Vol. IX, pp. 293–367.
*Minra, M.*, Untersuchungen über die motorischen Nervenendigungen
der quergestreiften Muskelfasern. Virchow’s Arch. 1886. Vol. CV,
p. 129.
*Nasse, O.*, Zur Anatomie und Physiologie der quergestreiften
Muskelfasern. Leipzig, 1882. Abstract in Centralbl. f. d. med.
Wiss. 1882, pp. 884 and 908.
*Newman, D.*, New theory of contraction of striated muscle and
demonstration of the composition of the broad dark bands. Journ.
of Anat. and Physiol. 1879, p. 4.
*Nicolaides, R.*, Ueber die caryokynetischen Erscheinungen der
Muskelkörper während des Wachstums der quergestreiften Muskeln.
Arch. f. Anat. u. Physiol. 1883, p. 441.
*Odenias, M. W.*, Undersökungen öfer de sensibla muskelnervena. Nord.
Medic. Arch. Vol. IV, No. 18.
*Paneth, J.*, Die Entwickelung von quergestreiften Muskelfasern aus
Sarkoplasten. Wiener Sitzungsber. 1886. Vol. XCII, Pt. III, p. 561.
*Petrowsky*, Zur Frage über das Wachstum der Muskelfasern des
Muskelgewebes beim Frosch. Med. Centralbl. No. 49, pp. 769–772.
*Pohl-Pincus*, Ueber die Muskelfasern des Froschherzens. Arch. f.
mik. Anat. 1884, Vol. XXIII, p. 500; and Verhandl. der Physiol.
Gesell. zu Berlin. 1882–3. No. 9.
*Ranvier, L.*, Appareils nerveux terminaux des muscles de la vie
organique; cœurs sanguins, cœurs lymphatiques; œsophagus; muscles
lisses. Leçons recueillies par Weber et Lataste. Leçons d’Anatomie
générale faites au Collège de France. Paris, 1880. Vol. VII,
p. 350.
*Ranvier, L.*, Leçons sur l’histologie du Système nerveux. 1878.
Vol. II.
*Reichert, K. E.*, Ueber das Verhalten der Nervenfasern bei dem
Verlauf und Endigung in einem Hautmuskel des Frosches, Rana
temporaria. Arch. f. Anat. u. Physiol. 1851, p. 29.
*Retzius*, Zur Kenntniss der quergestreiften Muskelfaser. Biologische
Untersuchungen. 1881, p. 1.
*Rouget*, Note sur la terminaison des nerfs moteurs dans les muscles
chez les reptiles, les oiseaux et les mammifères. Comptes rendus.
1862. LV, p. 548.
*Sachs, C.*, Die quergestreifte Muskelfaser. Arch. f. Anat. u.
Physiol. 1872, pp. 607–648.
*Sachs, C.*, Die Nerven der Sehnen. Arch. f. Anat. u. Physiol. 1875,
p. 402.
*Sandmann, D. G.*, Ueber die Verteilung der motorischen
Nervenendapparate in den quergestreiften Muskeln der Wirbelthiere.
Arch. f. Anat. u. Physiol. 1885, p. 240.
*Schönn*, Anatomische Untersuchungen im Bereich des Muskel- und
Nervengewebes. Jenaische Zeitschr. 1865. Vol. II, pp. 26–60.
*Schultze, M.*, Ueber Muskelkörperchen und das was man eine Zelle zu
nennen habe. Arch. f. Anat. u. Physiol. 1816, p. 17.
*Sokolow, A. A.*, Sur les transformations der terminaisons des nerfs
dans les muscles de la grenouille après les section des nerfs.
Arch. de Physiol. normale et pathologique, 1874, pp. 300–315.
*Sokolow, A. A.*, Ueber die Nervenendigungen in den Muskeln
ausgehungerter Frösche. Medicin. Bote. 1876, St. Petersburg.
*Tergast, P.*, Ueber das Verhältniss von Nerve und Muskel. Arch. f.
mik. Anat. 1873. Vol. IX, p. 36.
*v. Thanhoffer, L.*, Beiträge zur Histologie und Nervenendigung der
quergestreiften Muskelfasern. Arch. f. mik. Anat. 1882. Vol. XXI,
p. 26.
*Thin, G.*, On the structure of muscular fibre. Quart. Journ.
Microsc. Sci. 1877. Vol. XVI, pp. 251–259.
*Tolotschinoff*, Ueber das Verhalten der Nerven zu den glatten
Muskelfasern der Froschharnblase. Arch. f. mik. Anat. 1869.
Vol. V, p. 510.
*Trinchese, S.*, Mémoire sur la terminaison périphérique des nerfs
moteurs dans la série animale. Journ. de l’Anat. et de la Physiol.
1867, pp. 485–504 (original in Italian, 1867).
*Tschiriew, S.*, Sur les terminaisons nerveuses dans les muscles
striés. Arch. de physiol. norm. et path. 1879. Vol. VI, p. 89.
*Tschiriew, S.*, Sur les terminaisons nerveuses dans les muscles
striés. Compt. rend. 1878. Vol. LXXXVII, p. 604.
*Unger*, Untersuchungen über die quergestreiften Muskelfasern
des lebenden Thieres. Wiener med. Jahrb. 1879, p. 61; and in
Centralbl. f. d. med. Wiss. 1879, No. 34, p. 622.
*Wagener, G. R.*, Ueber die Verbindung von Muskel und Sehne unter
einander. Sitzungsber. naturw. Gesells. Marburg. 1874, pp. 38–46.
*Waldeyer, W.*, Ueber die Endigung der motorischen Nerven in den
quergestreiften Muskeln. Centralbl. f. d. med. Wiss. 1863, p. 369.
*Waldeyer, W.*, Untersuchungen über den Ursprung und den Verlauf
des Axencylinders bei Wirbellosen und Wirbelthieren, sowie über
dessen Endverhalten in der quergestreiften Muskelfaser. Henle and
Pfeuffer’s Zeitschr. 1864. Vol. XX, pp. 193–257.
*Weismann, A.*, Ueber die Musculatur des Herzens beim Menschen und in
der Thierreihe. Arch. f. Anat. u. Physiol. 1861, p. 41.
*Wolff, W.*, Ueber den Zusammenhang des Muskels mit der Sehne. Diss.
Berlin, 1877; Abstract in Centralbl. f. d. med. Wiss. 1877, p. 733.
Consult also: *Arnold, J., Kühne, W.*, and *Schweigger-Seidel, F.*,
in Stricker’s Handbuch der Gewebelehre.
II. CARTILAGE AND BONE.
*Arnold, J.*, Ueber die Abscheidung des indigschwefelsauren Natrons
im Knochengewebe. Virchow’s Arch. 1877. Vol. LXXI, p. 17.
*Arnold, J.*, Die Ausscheidung des indigschwefelsauren Narions im
Knorpelgewebe. Virchow’s Arch. 1878. Vol. LXXIII, p. 125.
*Bigelow, W. S.*, Notiz über den Theilungsvorgang bei Knorpelzellen
sowie über den Bau des Hyalinknorpels. Arch. f. mik. Anat. 1879.
Vol. XVI, p. 457.
*Boll, F.*, Untersuchungen über den Bau und die Entwicklung der
Gewebe. Arch. f. mik. Anat. 1871. Vol. VII, p. 275.
*Bruch, C.*, Ueber die Verknöcherung der Wirbelsäule bei den
Batrachiern. Würzb. naturw. Zeitschr. 1862. Vol. III, pp. 225–238.
*Bush, F.*, Das Knochengewebe der Batrachier nach den Untersuchungen
von N. Kastschenko. Verhandl. d. physiol. Gesells. zu Berlin.
1881, pp. 358–361.
*Flesch*, Untersuchungen über die Grundsubstance des Hyalinknorpels.
Würzburg, 1880.
*Heidenhain*, Zur Kenntniss des hyalinen Knorpels. Studien aus d.
physiol. Inst. zu Breslau. 1863. Pt. II, p. 1.
*Hertwig, O.*, Anatomisch histologische Untersuchung des Skelets der
Mundhöhle und der Zähne der Amphibien; supplement to Vol. XI.
Arch. f. mikroskopische Anat. 1874, pp. 29–32.
*Kastschenko, N.*, Ueber die Genese und Architectur der
Batrachierknochen. Arch. f. mik. Anat. 1881. Vol. XIX, pp. 1–52.
*Kastschenko, N.*, Ueber die Krappfärbung der Froschgewebe. Arch. f.
mik. Anat. 1882. Vol. XXI, p. 357.
*v. Kölliker*, Gewebelehre Leipzig. 1867, p. 66.
*Lehmann, J. C.*, Ueber den Knorpel in der Achillessehne des
Frosches. Zeitschr. f. wiss. Zool. 1864. Vol. XIV, p. 109.
*Levschin, L.*, Ueber die Entwicklung des Knochengewebes des
Frosches. Centralbl. f. med. Wiss. Nos. 18, 19.
*Mays, C.*, Ueber den Bau der Sehnen, etc. Virchow’s Arch. 1879.
Vol. LXXV, p. 112.
*Renaud, M. J.*, Système hyalin de soutènement des centres nerveux et
de quelques organes des sens. Arch. de Physiol. 1881, p. 6.
*Schleicher, W.*, Die Knorpelzelltheilung. Arch. f. mik. Anat. 1879.
Vol. XVI, P. 248.
*Spina, A.*, Ueber die Saftbahnen des hyalinen Knorpels. Wiener
Sitzungsber. 1879. Vol. LXXX, Pt. III, p. 267.
*Stadelmann, E.*, Die Histologie des ‘Pseudoknorpels’ in der
Achillessehne des Frosches, etc. Virchow’s Arch. 1880, Vol. LXXX,
p. 105; also as Dissert. inaug. Königsberg, 1878.
*van Stricht, O.*, Recherches sur le cartilage hyalin. Annales de la
société de médicine de Grand. 1885, pp. 221–232.
*Thin, G.*, On the structure of hyaline cartilage. Quart. Journ.
Micros. Sci. 1876. Vol. XVI, pp. 1–22.
*v. Török, A.*, Der feinere Bau des Knorpels des Achillessehne des
Frosches. Centralbl. f. d. med. Wiss. 1872, No. 5, p. 66; and
Verhandl. d. phys.-med. Gesells. zu Würzburg, 1872, Vol. III,
pp. 1–26.
III. THE CONNECTIVE TISSUES.
*Billroth, T.*, Ueber die Epithelzellen der Froschzunge, den Bau des
Cylinder- und Flimmerepithel und ihr Verhältniss zum Bindegewebe.
Arch. f. Anat. u. Physiol. 1858, p. 159.
*Bizzozero, G.*, Ueber den Bau des Sehnengewebes. Moleschott’s
Untersuchungen. 1876. Vol. XI, p. 36.
*Bobinzky, C.*, Zur Kenntniss des Baues, der Entwicklung and der
regressiven Metamorphose der Fetzellen. Centralbl. f. d. med.
Wiss. 1885. No. 43, pp. 753–755.
*Boll, F.*, Untersuchungen über den Bau und die Entwicklung der
Gewebe. Arch. f. mik. Anat. 1871. Vol. VII, p. 276.
*Ciaccio, G. V.*, Nuove Ricerche sull’ interna tessitura dei tendi.
Memorie dell’ Academie delle scienze dell Istituto di Bologna,
1872. Series III, Vol. II. Abstract in Centralbl. f. d. med. Wiss.
1873.
*Czumak, J.*, Notiz über elastische Sehnen. Centralbl. f. med. Wiss.
1863, p. 785.
*Flemming, W.*, Ueber Bildung und Rückbildung der Fettzelle im
Bindegewebe; und Bemerkungen über die Structur des letztern. Arch.
f. mik. Anat. 1871. Vol. VII, p. 32.
*Gerlach, J.*, Ueber Bindegewebe. Sitzungsb. d. phys.-med. Societät
zu Erlangen. 1872, p. 78.
*Ginsburg, L.*, Ueber das Verhalten der Sehnenzellen bei der
Entzündung. Virchow’s Arch. 1882. Vol. LXXXVIII, p. 263.
*Golgi, C.*, Sui Nervi dei Tendini dell’ Uomo e di altri Vertebrati e
di un nuovo Organo nervoso terminale Musculo-tendineo. Estr. dalle
Memorie della Reale Acc. di Torino. 1880. Series II, Vol. XXXII,
p. 29; No. 6, p. 86.
*Hensen, V.*, Ueber die Entwicklung des Gewebes und der Nerven im
Schwanze der Froschlarve. Virchow’s Arch. 1864. Vol. XXXI, p. 51.
*Hoyer*, Ueber den Bau der Cylinder- und Flimmerepithelien und ihr
Verhältniss zum Bindegewebe. Arch. f. Anat. u. Physiol. 1858,
p. 163; also Deutsche Klinik. 1857, No. 21.
*Iwanoff, A.*, Beiträge zur normalen und pathologischen Anatomie des
Frosch-Glaskörpers. Centralbl. f. d. med. Wiss. 1868, p. 129.
*Kollmann*, Ueber den Bau der Sehne. Münchener Sitzungsber. 1878.
Abstract in Centralbl. f. d. med. Wiss. 1879, p. 881.
*Maddox*, On the apparent relation of nerve to connective-tissue
corpuscles. Proc. Roy. Soc. Lond. 1868. Vol. XVI, p. 61.
*Mays, C.*, Ueber den Bau der Sehnen mit besondere Berücksichtigung
über Saftbahnen. Virchow’s Arch. 1879. Vol. LXXV, p. 112.
*Sachs, C.*, Die Nerven der Sehnen. Arch. f. Anat. u. Physiol. 1875,
p. 402.
*Spina, A.*, Untersuchungen des lebenden Bindegewebes. Oesterr. med.
Jahrb. 1884. Pt. II.
NOTE BY THE TRANSLATOR.
Reference has already been made to the views of Messrs. Melland and
Marshall on the structure of muscle-fibres. The opinion that the
striation of voluntary muscle is wholly or in part due to the presence
of a regularly arranged network was previously published by Retzius,
Bremer, and others. The authors referred to have now for the first
time shown the importance of this network in all vertebrate muscular
tissues, whether voluntary or involuntary.
Mr. Marshall gives the following summary of the result of his
researches, which the Translator has confirmed by his own
observations:--
1. In all muscles which have to perform rapid and frequent movements, a
certain portion of the muscle is differentiated to perform the function
of contraction, and this portion takes on the form of a very regular
and highly modified intracellular network.
2. This network, by its regular arrangement, gives rise to certain
optical effects which cause the peculiar appearances of striped muscle.
3. The contraction of the striped muscle-fibre is probably caused by
the active contraction of the longitudinal fibrils of the intracellular
network; the transverse networks appear to be passively elastic, and by
their elastic rebound cause the muscle to rapidly resume its relaxed
condition when the longitudinal fibrils have ceased to contract; they
are possibly also paths for the nervous impulse.
4. In some cases where muscle has been hitherto described as striped,
but gives no appearance of the network on treatment with the gold and
other methods, the apparent striation is due to optical effects caused
by a corrugated outline in the fibre.
5. In muscles which do not perform rapid movements, but whose
contraction is comparatively slow and peristaltic in nature, this
peculiar network is not developed. In most if not all of the unstriped
muscles of invertebrates there does not appear to be an intracellular
network present in any form, but in the unstriped muscle of vertebrates
there are longitudinal fibres only; these possibly represent a form
of network intermediate between the typical irregular intracellular
network of other cells and the highly modified network of striped
muscle.
6. The cardiac muscle-cells contain a network similar to that of
ordinary striped muscle.
DESCRIPTION OF THE FIGURES ON PLATE II.
Fig. 180 (p. 278).
I. Preparation of the mucous membrane of the dorsal surface of the
mouth and oesophagus to show the vascular supply. Arteries red,
veins blue; after Schöbl.
II. Small portion of the above to show the dilatations on the
capillaries; after Schöbl.
Fig. 187 (p. 285).
Transverse section through the mucous membrane of the fundus of the
stomach of _Rana esculenta_. Alcohol preparation, doubly stained
with carmine and anilin blue. After Biedermann. (Oc. II, Syst. 7,
Hartnack.)
Fig. 196 (p. 298).
I. Partial injection of the liver from the portal vein (blue): _Rana
esculenta_.--G. H.
II. Partial injection of the liver from the hepatic vein (red): _Rana
esculenta_.--G. H.
III. Complete injection of the liver from the hepatic artery (red) and
from the portal vein (blue): _Rana esculenta_.--G. H.
_A_ Portal (interlobular) veins and their branches.
_B_ Hepatic (intralobular) veins and their branches.
_C_ Hepatic arteries and their branches.
Fig. 208 (p. 318).
Two sections from the lung of _Rana temporaria_; stained with
borax-carmine.--G. H.
I. The lung dilated (Hartnack, Oc. I, Syst. 3).
II. The lung contracted (Hartnack, Oc. I, Syst. 7).
_A_ Band of muscle cut transversely.
_B_ Band of muscle cut longitudinally.
_C_ Muscular layer of surface.
Fig. 217 (p. 334).
Portions of two transverse vertical sections through the kidney.--G. H.
I. Kidney of _Rana esculenta_, partial injection of the uriniferous
tubes with silver nitrate (Hartnack, Oc. I. Syst. 7).
II. Kidney of _Rana temporaria_, stained with borax-carmine (Hartnack,
Oc. I, Syst. 7).
Fig. 219 (p. 337).
Two portions from a gold preparation of the kidney of _Rana
esculenta_.--G. H.
I. Showing the tendency to split into lobules.
II. Nerve-fibres accompanying the blood vessels.
_a_ Blood-vessels.
_b_ Nerves.
APPENDIX.
I. WORKS WHICH DESCRIBE ORGANS OR SETS OF ORGANS IN THE FROG.
*Bettade, E.*, Sulle diverse forme delle R. temp. in Europa e più
particolammente nell’ Italia. Venezia, 1885.
*Brehm, A. C.*, Illustriertes Thierleben. Hildburghausen, 1869. Vol. V.
*Burdon-Sanderson*, Handbook for the Physiological Laboratory. London,
1873.
*Camerana, L.*, Recherches sur les variations de in R. esculenta et du
Bufo viridis dans le bassin de la Méditerranée. Paris, 1883.
*Carus, C. G.*, Lehrbuch der vergleichenden Zootomie. 2nd Edit.
Leipzig, 1834.
*Cepède, Comte de la*, Histoire naturelle des quadrupèdes ovipaires et
des serpens. Paris, 1808.
*Dugès*, Recherches anatomiques et physiologiques sur les Reptiles.
Ext. des Annales des Sciences naturelles. Paris, 1827.
*Duméril and Bibron*, Erpétologie générale ou histoire complète des
Reptiles. 1836.
*Ecker, A.*, Icones physiologicae. Leipzig, 1851–1859.
*Fatio, V.*, Faune des vertébrés de la Suisse. Genève et Bâle, 1872.
*Gegenbaur, C.*, Grundzüge der vergl. Anatomie. Leipzig, 1870.
*Gegenbaur, C.*, Grundriss der vergl. Anatomie. Leipzig, 1878.
*Gerlach*, Handbuch der Histologie. 1853–1854.
*Gesner, C.*, Historia Animalium. Liber I. 1551.
*Gesner, C.*, Icones Animalium. 1560.
*v. Griesheim, A.*, Ueber die Zahlenverhältnisse der Geschlechter bei
R. fusca. Pflüger’s Arch. f. d. ges. Physiol. 1881. Vol. XXVI, p. 3.
*Hoffmann, C. K.*, Bronn’s Klassen und Ordnungen des Thierreichs.
Vol. VI, Amphibien. Leipzig, 1873–1878.
*Howes, G. B.*, An Atlas of Practical Elementary Biology. London, 1885.
*Huxley, T.*, Anatomy of the Vertebrated Animals. London, 1871.
*Huxley, T.*, Lectures on the Elements of Comparative Anatomy.
*Huxley, T.*, Article Amphibia, Encyclopaedia Britannica. IXth Edit.
1875.
*Klein, E.*, Beiträge zur Anatomie der ungeschwänzten Batrachier.
Jahreshefte. Württemberg, 1850, pp. 1–84.
*Klein, E.*, and *Noble Smith*, Atlas of Histology. London, 1879–1880.
*Kloezke, C. G.*, Dissertatio anatomica de Rana cornuta. Berolini, 1816.
*v. Kölliker, A.*, Handbuch der Gewebelehre. 5th Edit. Leipzig, 1867.
*Kuhl, H.*, Beiträge zur Zoologie der Rana esculenta: in Beitr. z.
Zool. Frankfurt a. M., 1820.
*Laurenti, J. N.*, Synopsis Reptilium. Viennae, 1768.
*Leydig, F.*, Lehrbuch der Histologie. Frankfurt a. M., 1857.
*Marshall, A. M.*, The Frog. 3rd Edit. London and Manchester, 1888.
*Mayer, A. F.*, Beiträge zu einer anatomischen Monographie der Rana
pipa. Acad. Caes. Leop. Nov. Acta, 1825. Vol. XII, p. 527.
*Meckel, J.*, Beiträge zur vergleichenden Anatomie. Leipzig, 1811.
*Meckel, J.*, System der vergleichenden Anatomie. Halle, 1833.
*Mivart, St. Geo.*, On the Classification of the Anurous Batrachians.
Proc. Zool. Soc. 1869.
*Mivart, St. Geo.*, The Common Frog. London, 1874.
*Müller, J.*, Beiträge zur Anatomie und Naturgeschichte der Amphibien.
Tiedemann’s Zeitschr. 1831, p. 190.
*Müller, J.*, The Physiology of the Senses, etc. Translated by W. Baly.
London, 1848.
*Owen, R.*, Anatomy of the Vertebrates. London, 1866.
*Ranvier, L.*, Leçons d’anatomie générale. Paris, 1880.
*Rösel v. Rosenhof*, Historia naturalis ranarum nostratium. Nürnberg,
1758.
*Rudolphi and Breyer*, Observationes anatomicae circa abricam Ranae
pipae. Berolini, 1811.
*Rusconi, M.*, Développement de la grenouille commune. Milan, 1826.
*Schneider, J. G.*, Historia amphibiorum. Jenae, 1799.
*Schwalbe, G.*, Lehrbuch der Anatomie der Sinnesorgane. Erlangen, 1885.
*Stannius, H.*, Zootomie der Amphibien (Handb. der Zoot. der
Wirbelthiere, 2 Buch). 2nd Edit. Berlin, 1856.
*Stricker, S.*, Beiträge zur Biologie der Batrachier. Wien. Zool. Bot.
Verhandl. 1866. Vol. XVI, pp. 451–456.
*Stricker, S.*, Handbuch der Gewebelehre.
*Stricker, S.*, Manual of Human and Comparative Histology. Translated
by H. Power. London, 1870.
*Swammerdam, J.*, Biblia Naturae Amstelodamensis. (Dutch and Latin by
Gaubius. Leidae, 1738.)
*Todd and Bowman*, The Physiological Anatomy and Physiology of Man.
London, 1845–1857.
*Vogt, C.*, Zoologische Briefe. Frankfurt a. M., 1851.
*Wagler, J.*, Natürliches System der Amphibien. München, Stuttgart, and
Tübingen, 1830.
*Wagner, R.*, Lehrbuch der vergleichenden Anatomie. Leipzig, 1834–1835.
*Wagner, R.*, Icones Zootomicae. Leipzig, 1841.
*Wagner, R.*, Handwörterbuch der Physiologie. 1842.
*Waters, W. H.*, Histological Notes. Manchester and London, 1884.
*Wiedersheim, R.*, Lehrbuch der vergleichenden Anatomie der
Wirbelthiere. 2nd Edit. Jena, 1886.
*Wiedersheim, R.*, Elements of Comparative Anatomy of Vertebrates.
Translated by N. Newton Parker. London, 1886.
II. WORKS RELATING TO THE EMBRYOLOGY AND DEVELOPMENT OF THE FROG.
*Balfour, F. M.*, Treatise on Comparative Embryology. London, 1880.
*Born, G.*, Beiträge zur Bastardirung zwischen den einheimischen
Anurenarten. Pflüger’s Arch. f. d. ges. Physiol. 1883. Vol. XXXII,
p. 453.
*Durham, H. E.*, Note on the presence of a Neurenteric Canal in Rana.
Quart. Journ. Micros. Sci. 1886. Vol. XXVI, p. 509.
*Giles, A. E.*, The development of the fat-bodies in Rana temporaria.
Quart. Journ. Micros. Sci. 1888. Vol. XXIX.
*Goette, A.*, Kurze Mittheilungen aus der Entwicklungsgeschichte der
Unke. Arch. f. mik. Anat. 1873. Vol. IX, p. 396.
*Goette, A.*, Entwicklungsgeschichte der Unke. Leipzig, 1875.
*Hertwig, O.*, Die Entwicklung des mittleren Keimblattes der
Wirbelthiere. Jena, 1883.
*Johnson, A.*, and *Sheldon, L.*, Notes on the Development of the Newt
(Triton cristatus). Quart. Journ. Micros. Sci. 1886. Vol. XXVI,
p. 573.
*Marshall, A. M.*, The Frog: An Introduction to Anatomy, Histology, and
Embryology. 3rd Edition. Manchester and London, 1888.
*Pflüger, E.*, Einige Beobachtungen zur Frage über die das Geschlecht
bestimmenden Ursachen. Pflüger’s Arch. f. d. ges. Physiol. 1881.
Vol. XXVI.
*Pflüger, E.*, Hat die Concentration des Samens einen Einfluss auf das
Geschlecht? Pflüger’s Arch. f. d. ges. Physiol. 1883. Vol. XXIX,
p. 1.
*Pflüger, E.*, Zusammenstellung der Ergebnisse und Erörterung der
Principien der Zeugung. Pflüger’s Arch. f. d. ges. Physiol. 1883.
Vol. XXXII, p. 542.
*Pflüger, E.*, and *Smith, W. J.*, Experimente über Bastardirung der
anuren Batrachier. Pflüger’s Arch. f. d. ges. Physiol. 1883.
Vol. XXXII, p. 519.
*Remak*, Untersuchungen über die Entwickelung der Wirbelthiere. Berlin,
1855.
*Schultze, O.*, Zur ersten Entwickelung des braunen Grasfrosches.
Leipzig, 1887.
*Schultze, O.*, Die Entwicklung der Keimblätter und der Chorda dorsalis
von Rana fusca. Zeitschr. f. wiss. Zool. 1888. Vol. XLVII, p. 325.
*Spencer, W. B.*, Some Notes on the Early Development of Rana
temporaria. Quart. Journ. Micros. Sci. 1885. (Supplement.)
*Stricker, S.*, Untersuchungen über die Entwicklung des Kopfes der
Batrachier. Arch. f. Anat. u. Physiol. 1864, p. 52.
*Törok, A.*, Beiträge zur Kenntniss der ersten Anlagen der Sinnesorgane
und der primären Schädelformation bei den Batrachiern. Moleschott’s
Untersuchungen, 1870. Vol. X, p. 338.
III. ADDITIONS TO THE LISTS GIVEN AT THE HEADS OF THE SECTIONS.
1. THE BONES.
*Albrecht, P.*, Note sur le basi-occipital des batraciens anoures.
Extr. d. Bullet. d. Musée royal d’hist. nat. de Belgique. 1883.
Vol. II.
*Born, G.*, Die sechste Zehe der Anuren. Morphol. Jahrb. 1876. Vol. I.
*Born, G.*, Ueber das Skelet des Fersenhöckers von Rana fusca, etc.
Sitzungsb. d. Schles. Gesell. f. vaterländ. Cultur. 1879.
*Born, G.*, Nachträge zu Carpus und Tarsus. Morph. Jahrb. 1880. Vol. VI.
*Ecker, A.*, Icones physiologicae. Leipzig, 1881–1889.
*Ecker, A.*, Die Anatomie des Frosches. 2nd Edition. Braunschweig,
1888, pp. 17–62.
*Gegenbaur*, Untersuchungen zur vergl. Anatomie der Wirbelsäule bei
Reptilien und Amphibien. Leipzig, 1862.
*Gegenbaur*, Grundzüge der vergl. Anatomie. Leipzig, 1870.
*Goette, A.*, Brustbein und Schultergürtel auf
entwickelungsgeschichtlicher Grundlage verglichen bei Amphibien und
Anurioten. Arch. f. mik. Anat. 1877. Vol. XIV, p. 502.
*Howes, G. B.*, On some abnormalities of the Frog’s vertebral column.
Anat. Anz. 1886. Vol. I, Pt. II.
*Leydig, F.*, Ueber den Bau der Zehen bei Batrachiern und die Bedeutung
des Fersenhöckers. Morphol. Jahrb. 1876. Vol. II.
*Parker, W. K.*, A monograph on the structure and development of the
shoulder-girdle and sternum. Ray. Soc. 1867.
*Schneider, J. G.*, Historia amphibiorum. Jenae, 1799.
*Stöhr, P.*, Zur Entwickelungsgeschichte des Anurenschädels. Zeitschr.
f. wiss. Zool. 1881. Vol. XXXVI.
*Törok, A.*, Beiträge zur Kenntniss der ersten Anlagen der Sinnesorgane
und der primären Schädelformation bei den Batrachiern. Moleschott’s
Untersuchungen. 1870. Vol. X, p. 338.
2. THE MUSCLES.
*Albrecht, P.*, Beitrag zur Morphologie des M. omohyoides und der
ventralen inneren Interbranchial-Musculatur. Inaug. Dissert. Kiel,
1876.
*Ecker, A.*, Die Anatomie des Frosches. 2nd Edition. Braunschweig,
1888, pp. 65–139.
*Hoffmann, C. K.*, Bronn’s Klassen und Ordnungen des Thierreichs.
Vol. VI. Amphibien. Leipzig, 1873–1878.
*Howes, G. B.*, An Atlas of Practical Elementary Biology. London, 1885.
3. NERVOUS SYSTEM.
*Engelmann, T. W.*, Ueber die Discontinuität des Axencylinders und
den fibrillären Bau der Nervenfasern. Pflüger’s Arch. f. d. ges.
Physiol. 1880. Vol. XXII, p. 1.
*Grandry*, Recherches sur la structure interne du cylindre de l’axe et
des cellules nerveuses. Bull. de l’Acad. Roy. du Belgique. 1868.
*Hodge, C. F.*, Some effects of stimulating ganglion-cells. (Some
anatomical details regarding the relations of nerve-fibres with
nerve-cells are given.) American Journ. of Phys. 1888.
*Owsjannikow, P.*, Ueber die Rinde des Grosshirns. Mémoires de l’acad.
impériale des sciences de St. Pétersbourg. 1879. Series VII,
Vol. XXVI, No. 11.
*Spiro*, Physiologisch-topographische Untersuchungen am Rückenmark
des Frosches. Mémoires de l’acad. impériale des sciences de St.
Pétersbourg. 1870. Series VII, Vol. XVI, No. 7.
*Waldeyer, W.*, Untersuchungen über den Ursprung und Verlauf des
Axencylinders. Henle u. Pfeuffer’s Zeitschr. 1864. Vol. XX,
pp. 193–257.
Consult also: *Gerlach, J.*, *Mayer, S.*, and *Schultze, M.*, in
Stricker’s Handbuch der Gewebelehre.
4. THE VASCULAR SYSTEM.
*Barthol, P.*, Sopra il sistema linfatico dei Rettili. Pavia, 1833.
*Blaschek, A.*, Untersuchungen über Herz, Pericard, Endocard, und
Pericardhöhle. Schenk’s Mitt. 1885. New Series, p. 32.
*Eberth, C. J.*, in Stricker’s Handbuch der Gewebelehre.
*Klein, E.*, On the peripheral distribution of non-medullated
nerve-fibres (nerves of the blood-vessels in the frog’s tongue).
Quart. Journ. Micros. Sci. 1872. Vol. XII, p. 123.
*Mayer, S.*, Studien zur Histologie und Physiologie des
Blutgefässsystems. Wiener Sitzungsb. 1886. Vol. XCIII, Pt. III,
p. 45.
*v. Recklinghausen, F.*, (The lymphatics) in Stricker’s Handbuch der
Gewebelehre.
*Rollett, A.*, (The Blood) in Stricker’s Handbuch der Gewebelehre.
*Teichmann, L.*, Untersuchungen über das Saugadersystem. Leipzig, 1861.
5. THE ALIMENTARY CANAL.
*Heidenhain, R.*, Beiträge zur Kenntniss des Pancreas. Pflüger’s Arch.
f. d. ges. Physiol. 1875. Vol. X, p. 557.
*Krause, W.*, Anatomische Untersuchungen (Tongue). Hannover, 1861.
Consult also: *Klein, E.*, The Oral Cavity and the Oesophagus; *Müller,
W.*, The Spleen; *Eberth, C. J.*, The Liver, in Stricker’s Handbuch
der Gewebelehre.
6. THE LUNGS AND LARYNX.
*Holmgren, F.*, Methode zur Beobachtung des Kreislaufs in der
Froschlunge. Beitr. z. Anat. u. Physiol. Festgabe f. C. Ludwig.
Leipzig, 1874.
*Meckel, J. F.*, Beiträge zur Geschichte des Respirations-Systemes der
Amphibien. Meckel’s Arch. 1849. Vol. V.
*Schmidt, C.*, De l’épithelium pulmonaire. 1866.
*Williams*, Article Respiration, in Todd’s Cyclopaedia of Anat. and
Physiol. 1859. Vol. V.
7. THE URINO-GENITAL SYSTEM, THE ADRENALS, AND THE FAT-BODIES.
*Aeby, C.*, Ueber glatte Muskelfasern im Ovarium und Mesovarium von
Wirbelthieren. Arch. f. Anat. u. Physiol. 1859, p. 675.
*Giles, A. E.*, The development of the fat-bodies in Rana temporaria.
Quart. Journ. Micros. Sci. 1888. Vol. XXIX.
*Grohe, F.*, Ueber die Bewegung der Samenkörper. Virchow’s Arch. 1865.
Vol. XXXII, p. 416.
*Virchow, R.*, Ueber die Dotterplättchen bei den Fischen und Amphibien.
Zeitschr. f. wiss. Zool. 1849. Vol. IV.
Consult also: *Eberth, C. J.*; *v. La Valette St. George*; *Ludwig,
C.*; *Grünwald*; *Obersteiner, H.*; and *Stricker, S.*, in
Stricker’s Handbuch der Gewebelehre.
8. THE SKIN AND SENSE-ORGANS.
a. _The Skin._
*Busch, A.*, Phänomene aus dem Leben der Pigmentzellen. Arch. f. Anat.
u. Physiol. 1856, p. 415.
b. _Special Organs of Tactile Sensation._
*Mitrophanow, P.*, Zur Entwicklungsgeschichte und Innervation der
Nervenhügel der Urodelenlarven. Biologisches Centralb. 1887, p. 174.
c. _The Organs of Taste._
*Beale, L. S.*, New Observations upon the Minute Anatomy of the
Papillae of the Frog’s Tongue. Phil. Trans. 1865. Vol. CLV, p. 443.
*Engelmann, T. W.*, in Stricker’s Handbuch der Gewebelehre.
*Maddox, R. L.*, A Contribution to the Minute Anatomy of the Fungiform
Papillae and terminal arrangement of Nerve to striped Muscular
Tissue in the Tongue of the common Frog. Monthly Micros. Journ.
1869, p. 1.
d. _The Ear._
*Albrecht, P.*, Sur la valeur morphologique de la trompe d’Eustache.
Communication faite à la Société d’Anatomie Pathologique de
Bruxelles. 1884.
*v. Kölliker*, Handbuch der Gewebelehre. 5th Edit. Leipzig, 1867.
*Leydig, F.*, Handbuch der Histologie. Frankfurt a. M., 1857.
*Rüdinger*, in Stricker’s Handbuch der Gewebelehre.
e. _The Nose._
*Marshall, A. M.*, Morphology of the Vertebrate Olfactory Organ. Quart.
Journ. Micros. Sci. 1879. Vol. XIX, p. 330.
f. _The Eye._
*Ciaccio, G. V.*, Beobachtungen über den inneren Bau des Glaskörpers im
Auge des Menschen und der Wirbelthiere im Allgemeinen. Moleschott’s
Untersuchungen, 1870. Vol. X, p. 383.
*Hannover* and *Finkbeiner*, Vergleichende Untersuchungen der Stärke
des Glaskörpers bei den Wirbelthieren. Zeitschr. f. wiss. Zool.
1855. Vol. VI, p. 335.
*Hirschberg, J.*, Zur Dioptric und Ophthalmologie der Fish- und
Amphibienaugen. Arch. f. Anat. u. Physiol. 1887, p. 493.
*Ranvier, L.*, Le mécanisme de la Sécrétion. Leçons faites au Collége
de France en 1886–1887. (Nictitating membrane.)
Consult also: *Rollett* and *Stieda*, in Stricker’s Handbuch der
Gewebelehre.
INDEX.
Abducens nerve, p. 171.
" nucleus, 146.
Acetabulum, 48.
Acromial, 39.
Adrenals, 348.
Ala magna, 25.
" temporalis, 25.
Alar cartilages, 28.
Alimentary canal, 258.
Ampulla anterior, 396.
" external, 398.
" posterior, 398.
Angulo-splenial, 34.
Ankle, 50.
Anterior ampulla, 396.
" brachial lymph-sac, 259.
" brachio-radial septum, 258.
" brachio-ulnar septum, 258.
" chamber, 409.
Aorta dorsal, 233.
Aponeurosis plantaris, 105.
Arachnoid, 162.
Arteria basillaris, 163.
" bulbi, 222.
" circumflexa genu. lat. sup., 238.
" " " " inf., 238.
" " " med. sup., 238.
" " " " inf., 238.
" comm. ant., 163.
" coraco-clavicularis, 231.
" costo-cervicalis, 231.
" cruris inf., 239.
" cut. calcanei, 239.
" cut. fem. med., 237.
" " " post., 237.
" " pectoris, 231.
" haemorrhoid. inf., 236.
" lobi hemisph. inf. ext., 163.
" " " sup. int., 163.
" " optici, 163.
" malleol. lat., 240,
" malleol. med., 240.
" pharyngo-maxill., 230.
" ramus auricularis, 228, 230.
" " maxillaris comm., 228.
" " " inf., 230.
" " " sup., 228.
" " orbito-nasalis, 228.
" scapularis post., 232.
" " sup., 232.
" spinalis ant., 163.
" subscapularis, 232.
" suralis, 239.
Arteries, 222.
" of brain, 162.
" of choroid, 411.
" of foot, 240.
" of hyaloid, 421.
" of iris, 413.
" of skin, 376.
" of vitreous body, 421.
Artery, ant. palatine, 224.
" " tibial, 239.
" brachial, 232.
" carotid, 224.
" ciliary, 226.
" coeliaco-mesenteric, 233.
" femoral, 236.
" gastric, 233.
" haemorrhoidal, 235.
" hepatic, 298.
" hyaloid, 226.
" iliac, 235.
" internal carotid, 225.
" laryngeal, 226.
" lingual, 224.
" lumbar, 235.
" mesenteric, 234.
" occipital, 228.
" occipito-vertebral, 226.
" oesophageal, 226.
" ophthalmic, 225, 411, 413.
" peroneal, 231.
" pharyngeal, 224.
" post. palatine, 224.
" radial, 232.
" renal, 333.
" sciatic, 236.
" spermatic, 236.
" subclavian, 231.
" tibial, 238.
" ulnar, 233.
" urino-genital, 235.
" vertebral, 226.
" vesico-epigastric, 235.
Articular processes, 17.
Articulations of vertebrae, 19.
" of atlas, 24.
Arytenoid cartilages, 313.
Astragalus, 50.
Atlas, 18.
Auditory nerve, 172.
Auditory nucleus, 144.
Auerbach’s plexus, 292.
Auricles, 214.
Auriculo-ventricular valves, 216.
Axillary septum, 258.
Axis-cylinder, 202.
Bidder’s ganglion, 220.
Bile-ducts, 298.
Bladder, gall-, 295, 299.
" urinary, 338.
Blood, 262.
Bones and joints, 13.
Bowman’s glands, 387.
Brachial nerve, 183.
Brachio-ulnar lymph-sac, 259.
" radial " , 259.
Brain, 141.
Calcaneum, 50.
Calcified cartilage, 15.
Canales coccygei, 21.
Canalis vertebralis, 20.
" rami ant. acustici, 393.
Capitulum radii, 43.
Capsule of labyrinth, 391.
" of lens, 413.
Carotid arch, 222.
" gland, 223.
Cartilage, calcified, 15.
" of shoulder-girdle, 40.
" of skull, 29.
Cartilages of larynx, 312.
" of nose, 27, 385.
Cauda equina, 135, 189.
Cava recto-vesicalis, 304.
Cavitas sigmoidea maj., 43.
Central canal of cord, 137.
" group of cells, 139.
Cerebellum, 148.
Cerebral hemispheres, 156.
Chamber, anterior, 409.
" posterior, 420.
Chiasma, optic, 153, 155, 167.
Chorda dorsalis, 20.
Chordae tendineae, 216.
Choroid coat, 409.
" plexus of fourth vent., 142, 164.
" " third " , 153, 164.
Ciliary nerves, 169.
" processes, 420.
Circulus iridis major, 413.
Clavicle, 39.
Cloaca, 347.
Columella auris, 25, 390.
Commissura anterior, 159.
" inferior, 140.
" posterior, 159.
" superior, 140.
" transversa, 154.
Common bile-duct, 296.
Cones, 418.
Conus medullaris, 135.
Coracoid, 39.
Coracoid foramen, 39.
Cornea, 406.
Corpora quadrigemina, 152.
Corpus callosum, 158, 159.
" striatum, 158, 159.
Corpuscles of blood, 263.
" of Hassall, 321.
Coverings of brain and cord, 162.
Cranial nerves, 141, 167.
Cranium, 23.
Cricoid cartilage, 312.
Crista acustica, 397.
" deltoidea, 41.
" medialis, 42.
Crusta, petrosa, 279.
Cupula terminalis, 398.
Cutaneous glands, 372.
Cuticula dentis, 279.
Cutis, 369.
Cystic duct, 295.
Dentale, 35.
Dentary, 34.
Dentine, 279.
Descemet’s membrane, 407.
Dorsal lymph-sac, 255.
" roots, 140.
" septum, 252.
Duct, common bile-, 296.
" cystic, 295.
Ductus choledocus, 296.
" endolymphaticus, 398.
" fenestra ovalis, 394.
" perilymphaticus, 395.
" Wirsungianus, 301.
Dura mater, 162.
Ear, 389.
Enamel, 279.
Enlargements of cord, 133, 137.
Epicoracoids, 37.
Epidermis, 367.
Epiglottis, 317.
Episternum, 36.
Epithelium of ventricles, etc., 160.
Exoccipitals, 23.
External limiting membrane, 420.
Extrastapedial, 26, 390.
Eye, 405.
Eyelids, 422.
Facial nerve, 171.
Fat-bodies, 348.
Femoral lymph-sac, 260.
Fibrae arcuatae cerebelli, 149.
Fibres of brain, 161.
Filiform papillae, 380.
Filum terminale, 135.
Foramen condyloideum, 24.
" magnum, 23.
" Monroi, 157.
" ovale, 24.
" parietale, 156.
" rotundum, 392.
Formatio reticularis, 140.
Fossa condyloidea, 24.
" tympanica, 24.
Fourth ventricle, 142.
Fronto-parietal bones, 26.
Fungiform papillae, 380.
Gall-bladder, 295, 299.
Ganglia of bladder, 340.
" of heart, 220.
" of spinal, 177.
Ganglion ciliare, 168.
" condyloideum, 173.
" Gasserii, 168.
" interpedunculare, 152.
" layer, 415.
" nervi vagi, 173.
Gasserian ganglion, 168.
Glands, Bowman’s, 387.
" cutaneous, 372.
" gastric, 285.
" Harder’s, 424.
" intermaxillary, 280.
" Lieberkühn’s, 288.
" nasal, 386.
" oesophageal, 283.
" of nictitating membrane, 423.
" periganglionic, 180.
" thymus, 320.
" thyroid, 322.
Glossopharyngeal nerve, 172.
Goblet-cells, 289.
Goll’s columns, 140.
Grey matter, 139.
Hair-cells of ear, 404.
" of nose, 388.
Harder’s glands, 424.
Hassall’s corpuscles, 321.
Heart, 213, 214.
" endothelium, 320.
" muscle, 216.
" nerves, 219.
" structure of, 216.
Hepatic arteries, 421.
" portal system, 248.
" veins, 297.
Hip-joint, 49.
Humerus, 41.
Hyaloid artery, 421.
" membrane, 421.
Hyoid, 35.
Hypoglossal nerve, 182.
Ilia, 47.
Iliac lymph-sac, 257.
" septum, 253.
Inferior femoral septum, 259.
" sinus, 383.
Infundibulum, 153.
Inguinal septum, 254.
Inner molecular layer, 415.
" nuclear " , 416.
Interfemoral lymph-sac, 260.
Intermaxillary glands, 280.
Intermediate fem. septum, 259.
Internal ear, 391.
" limiting membrane, 414, 420.
" muscles of eye, 413.
Interstapedial, 25, 391.
Intestine, 286.
Intumescentia ant. and post., 135.
Iris, 412.
Ischia, 48.
Kidney, 332.
Knee-joint, 50.
Labyrinth membranous, 395.
" osseous, 391.
" structure, 402.
Lachrymal duct, 387.
Lagena cochlea, 400.
Lamina fusca, 411.
" suprachoroidea, 411.
" terminalis, 153, 157.
Large intestine, 292.
Laryngeal nerve, 175.
Larynx, 311.
Lateral group of cells, 139.
" lymph-sac, 255.
" sense-organs, 379.
" sinus, 380.
Lens, 413.
Lieberkühn’s glands, 288, 293.
Ligament. calcanei, 19.
" coronarium, 303.
" gastro-duodenale, 305.
" hepato-duodenale, 287, 295, 305.
" intercruralia, 19.
" interspinalia, 19.
" pectinatum iridis, 409.
" suspensor. hepatis, 304.
" verteb. comm. ant., 19.
" " " post., 19.
Limiting membrane, external, 420.
" " internal, 414, 420.
Lips, 275.
Literature on adrenals, 330.
" " alimentary canal, 268.
" " blood, 211.
" " blood-vessels, 205.
" " bones and joints, 13.
" " cartilage, 431.
" " connective tissues, 432.
" " ear, 356.
" " embryology, 436–437.
" " eye, 360.
" " fat-bodies, 330.
" " gall-bladder, 272.
" " general, 435–436.
" " heart, 205.
" " intestine, 270.
" " larynx, 309.
" " liver, 272.
" " lungs, 309.
" " lymph, 211.
" " lymphatic system, 209.
" " mouth, 268.
" " muscle structure, 427.
" " muscles, 54.
" " nervous system, 122.
" " nose, 357.
" " pancreas, 272.
" " peritoneum, 274.
" " respiratory system, 309.
" " skin, 353.
" " spleen, 273.
" " taste-organs, 356.
" " thymus, 310.
" " thyroid, 310.
" " touch-organs, 356.
" " urino-genital system, 326.
Liver, 294.
" cells, 298.
" pigment of, 299.
" vessels of, 297.
Lower eyelid, 422.
" nasal glands, 386.
Lungs, 317.
Lymph, 264.
Lymph-hearts, 261, 264.
Lymph-sacs of ant. extremity, 258.
" " of hinder extremity, 259.
" " of trunk, 251, 255, 264.
Lymphatic system, 251.
Macula lutea, 419.
Malpighian bodies of kidney, 334.
" " of spleen, 303.
Mandible, 34.
Maxillary bones, 32.
" septum, 253.
Meckel’s cartilage, 35.
Mediostapedial, 25, 390.
Medulla oblongata, 142.
Medullary segments, 202.
" sheath, 201.
Medullated nerves, 201.
Meissner’s plexus, 291.
Membrana choriocapillaris, 411.
" limitans ext., 420.
" " int., 414, 420.
" nictitans, 58, 422.
" suprachoroidea, 411.
Membrane of Descemet, 407.
Membranous labyrinth, 395.
Mentomeckelian cartilage, 35.
Mesocephalic ganglion, 168.
Metacarpus, 46.
Metatarsus, 52.
Meynert’s fibres, 155.
Molecular layer, inner, 415.
" " outer, 419.
Motor-oculi, 167.
Mouth, 275.
Movements of hand, 46.
Mucous glands of skin, 375.
Müller’s fibres, 420.
Muscle, histology, 433.
Muscles, 53.
Muscles of abdomen, 67.
" " back, 71.
" " cloaca, 347.
" " eye, external, 55.
" " " internal, 413.
" " face, 59.
" " foot, 105.
" " forearm, 84.
" " forelimb, 75.
" " hand, 87.
" " hinder limb, 94.
" " hyoid, 64.
" " larynx, 315.
" " lower jaw, 60.
" " skin, 119.
Musc. abduct. dig. I brev., 114.
" " " II " , 92.
" " " " long., 91.
" " " V, 113.
" " " V brev., 116.
" " " I long., 110.
" " " II " , 86.
" " " V prim., 91.
" " " V secund., 91.
" " hallucis, 109.
" " pollicis, 87.
" " brev., 114.
" adduct. brev., 100.
" " dig. I long., 109.
" " " II, 89.
" " " V, 113.
" " longus, 99.
" " magnus, 99.
" " pollicis, 87.
" anconaei, 87.
" antibrachii lat., 85.
" " med., 85.
" " prof., 85.
" biceps fem., 96.
" coccygeo-cutaneus, 120.
" " -iliacus, 74.
" coccygeo-sacralis, 73.
" compressor cloacae, 348.
" constrictor aditus laryngis, 315.
" constrictor iridis, 413.
" coraco-humeralis, 82.
" cucullaris, 71.
" cutaneus dorsi, 119.
" " pectoris, 119.
" dilator aditus laryngis, 315.
" deltoideus, 82.
" depressor maxill. inf., 60.
" " palpebrae inf., 58.
" dilator iridis, 413.
" " narium, 59.
" extensor brevis, 106.
" " carpi ulnaris, 86.
" " cruris brevis, 104.
" " digit. I brev., 114.
" " " " long., 114.
" " " II brev., 114.
" " " " long., 114.
" " " " prop. brev., 92.
" " " " " long., 92.
" " " III brev., 115.
" " " " long., 115.
" " " " prop., 93.
" " " IV, 116.
" " " " brev., 116.
" " " " prop., 93.
" " " V brev., 115.
" " " " long., 115.
" " " " comm. brev., 91.
" " " " " long., 87.
" " dorsi com m., 73.
" flex. antibrach. lat. superf., 85.
" " " med., 85.
" " " prof., 85.
" " brev. digit. I, 100.
" " " " IV, 112.
" " " " V, 113.
" " carpi radialis, 84.
" " " ulnaris, 84.
" " digit. comm., 85, 87.
" " " I, II, 108.
" " " II brev., 89.
" " " II long., 88.
" " " II prop., 110.
" " " II tert., 89.
" " " III brev., 89.
" " " III long., 89.
" " " III prop., 111.
" " " III, IV, V, 107.
" " " IV brev., 90.
" " " " long., 90.
" " " " prop., 112.
" " " V brev., 90.
" " " " long., 90.
" " " " prop., 113.
" " metacarp. digit. III, 90.
" " " " IV, 90.
" " metatars. digit. II, 110.
" " " " III, 111.
" " metatars. digit. IV, 112.
" " phal. prop. dig. III, 112.
" " " " " IV, ant., 113.
" " " " " IV, post., 113.
" " " " " V, 90.
" " " " , 113.
" " tarsi ant., 104.
" " " post., 114.
" gastrocnemius, 102.
" genioglossus, 66, 281.
" geniohyoideus, 64.
" glutaeus, 94.
" hyo-arytenoideus anterior, 315.
" " posterior, 315.
" hyoglossus, 66, 281.
" ilio-fibularis, 96.
" ilio-lumbaris, 74.
" ilio-psoas, 101.
" infraspinatus, 79.
" intercrurales, 75.
" interossei, 93, 113.
" " dorsales, 116.
" interscapularis, 78.
" intertransversar. cap. sup., 75.
" " " " inf., 75.
" " " dorsi, 75.
" lateralis narium, 60.
" latissimus dorsi, 72.
" levator ang. scap., 76.
" " bulbi, 57.
" longissimus dorsi, 72.
" lumbricales, 108.
" masseter, 62.
" nasalis ext., 60.
" obliquus ext., 67
" " inf., 56.
" " int., 67.
" " sup., 56.
" obturat., 182.
" omohyoideus, 65.
" opponens dig. I, 110.
" " " II, 89.
" " " V, 90.
" palmaris brev., 87.
" pectineus, 100.
" pectoralis, 80.
" petrohyoideus ant., 65.
" petrohyoidei post., 66, 315.
" plantaris, 107.
" protrahens scap., 76.
" pterygoideus, 61.
" pyriformis, 95.
" quadratus fem., 112.
" rectus abdom., 67.
" " extern. bulbi, 55.
" " fem. ant., 95.
" " infer. ", 55.
" " inter. ", 55.
" " intern. major, 97.
" " super. ant., 56.
" " intern. minor, 98.
" retractor bulbi, 56.
" sartorius, 97.
" semimembranosus, 97.
" semitendinosus, 100.
" sphincter ani, 347.
" sternohyoideus, 64.
" sternomastoideus, 76.
" sternoradialis, 82.
" submaxillaris, 62.
" submentalis, 63.
" subscapularis, 78.
" temporalis, 61.
" tibialis ant., 104.
" " post., 103.
" transverso-scapularis major, 77.
" " " minor, 77.
" transversus metacarp., 93.
" " plant., 108.
" triceps femoris, 95.
" vastus ext., 96.
" " int., 96.
Nasal bones, 33.
" cartilages, 385.
" glands, 403.
Nephrostomes, 336.
Nerve, abducens, 171.
" auditory, 172.
" brachial, 183.
" facial, 171.
" fifth spinal, 187.
" fourth spinal, 188.
" glossopharyngeal, 172.
" hypoglossal, 182.
" laryngeal, 175.
" oculo-motor, 167.
" olfactory, 167.
" optic, 167, 405.
" pathetic, 142, 168.
" palatine, 169.
" peroneal, 195.
" pneumogastric, 173.
" radial, 186.
" sixth spinal, 188.
" spinal, 175.
" structure of, 201.
" sympathetic, 197.
" third spinal, 188.
" tibial trigeminal, 168.
" vagus, 173.
Nerves, 167.
" of Cornea, 408.
" " ear, 403.
" " heart, 219.
" " lungs, 319.
" " oesophagus, 286.
" " skin, 378.
" " stomach, 286.
Nervi ciliares, 169.
Nervus coccygeus, 189.
" coraco-clavicularis, 183.
" cruralis, 189.
" cut. antibrach. inf., 185.
" cut. antibrach. sup., 185.
" cut. dorsi pedis lat., 196.
" ileo-hypogastricus, 189.
" peroneus, 195.
" " comm. inf., 196.
" " lateralis, 196.
" " medialis, 196.
" ramus accessorius, 174.
" " anterior, 173.
" " auricularis, 172.
" " cardiacus, 175.
" " cut. axillaris, 183.
" " cutaneus dors., 174.
" " " cruris lat., 196.
" " " " med., 194.
" " " " post., 194.
" " " fem., 189.
" " " lat., 187.
" " " med., 186.
" " " sup., 186.
" " dorsalis, 185.
" " gastricus, 175.
" " hyoideus, 172.
" " hyomandibularis, 172.
" " laryngeus, 175.
" " lateralis, 185.
" " mandibularis, 170.
" " maxillaris, 170.
" " maxillo-mandibularis, 170.
" " muscularis, 187.
" " ophthalmicus, 169.
" " palatinus, 171.
" " pectoralis, 185.
" " posterior, 173.
" " pulmonalis, 175.
" " scapularis, 174.
" " subscapularis, 185.
" " ulnaris lat., 186.
" " " med., 185.
" tibialis, 194, 195.
Neurilemma, 201.
Nictitating membrane, 422.
Non-medullated fibres, 202.
Nose, 383.
" skeleton, 27, 383, 385.
Nuclear layer, inner, 416.
" " outer, 416.
Nucleus abducens, 146.
" auditory, 144.
" centralis, 144.
" magnus, 147, 152.
" medullae oblongatae, 144.
" pneumogastric, 146.
" trigeminal, 145.
Oculo-motor nerve, 167.
" nucleus, 151.
Oesophageal glands, 283.
Oesophagus, 282.
Olfactory nerve, 167.
Omosternum, 36.
Operculo-angulare, 35.
Operculum, 25.
Optic chiasma, 153, 155, 167.
" commissure, 154.
" fibre layer, 414.
" lobes, 149.
" nerve, 167, 405.
" tracts, 152.
Os articulare, 35.
" capitato-hamatum, 45.
" cuboideum, 51.
" cuneiformia, 52.
" en ceinture, 27.
" lunatum, 44.
" multangulum maius, 45.
" " minus, 45.
" naviculare of foot, 51.
" " of hand, 45.
" occipitale basilare, 23.
" " superius, 23.
" pyramidale, 44.
Ostium abdominale, 304, 345.
Outer nuclear layer, 416.
Ovaries, 344.
Oviducts, 304, 345.
Palatine artery, 224.
" bones, 33.
" nerves, 169.
Pancreas, 300.
Papilla acustica lagenae, 400.
Papillae of skin, 370.
" of tongue, 380.
Parasphenoid, 26.
Pars basilaris cochleae, 400.
" commissuralis, 147, 152.
" media, 135.
" neglecta, 400.
" peduncularis, 143, 152.
Partes condyloideae, 23.
Pathetic nerve, 142, 168.
Pectoral lymph-sac, 255.
" septum, 253.
Pelvis, 47.
Pericardium, 213.
Periganglionic glands, 180.
Perilymphatic space, 393.
Perineal septum, 253.
Peritoneum, 303.
Phalanges of foot, 52.
" " of hand, 47.
Pia mater, 162.
Pigment of cerebellum, 149.
" " cord, 141.
" " hemispheres, 160.
" " liver, 299.
" " medulla, 148.
" " optic lobes, 152.
" " thalamencephalon, 155.
" " skin, 369.
Pigment-layer, 419.
Pineal body, 155.
Pituitary body, 154, 156.
Plexus, Auerbach’s, 292.
" lateralis, 165.
" Meissner’s, 291.
Pneumogastric nerve, 146, 173.
" " nucleus, 146.
Pons Varolii, 149.
Portal systems, 247.
" vein, 297.
Posterior chamber, 420.
Pre-arytenoid cartilages, 314.
Precoracoid, 40.
Premaxillary bones, 33.
Processes, articular, 17.
" spinous, 17.
" transverse, 17.
Processus coracoideus, 40.
" coronoideus, mandible, 34.
" " " radio-ulnar, 43.
" mastoideus, 24.
" zygomaticus, 30.
Prootic bones, 24.
Pterygoid bones, 31.
Pubes, 49.
Pulmo-cutaneous arch, 230.
Pulp-cavity, 279.
Purkinge’s cells, 148.
Radio-ulnar, 43.
Rami communicantes, 181, 199.
Rana aquatica, 3.
" esculenta, 4.
" flaviventris, 7.
" gibbosa, 3.
" innoxia, 3.
" oxyrhinus, 7, 9.
" rubeta, 3.
" temporaria, 7.
Receptaculum seminis, 337.
Recessus utriculi, 396.
Remak’s ganglion, 220.
Renal arteries, 333.
" portal vein, 332.
" veins, 333.
Reproductive organs, 341.
Retina, 414.
Retinal pigment, 419.
Ritter’s fibres, 418.
Rods and cones, 416.
Roots of spinal nerves, 175.
Round bundle, 154, 159.
Saccus endolymphaticus, 395, 398.
" fenestra ovalis, 395.
" perilymphaticus, 395.
Sacrum, 19.
Scapula, 37.
Sciatic artery, 236.
" nerve, 192.
" plexus, 191.
Sclerotic coat, 405.
Semicircular canal, ant., 396.
" " ", ext., 398.
" " ", post., 398.
Septa, of lymph-sacs, 252.
Septum medium, 139.
Serous glands of skin, 372.
Shoulder-girdle, 37.
" -joint, 42.
Sinus, superior, 383.
Sinus venosus, 214.
Skeleton, 15.
" of nose, 27, 383, 385.
Skin, 367.
Skull, 21.
Small intestine, 286.
Sphenethmoid, 27.
Spinal cord, 135.
" ganglia, 177.
" nerves, 135, 175, 181.
" roots of, 175.
Spinous processes, 17.
Spleen, 302.
Squamosal bones, 30.
Sternum, 36.
Styloid cartilage, 25.
Submaxillary lymph-sac, 255.
Substantia reticulosa, 138.
Sulcus longitud. inf., 135.
" " sup., 135.
Superior sinus, 383.
Supplemental toe, 5, 47, 374.
Supra-femoral lymph-sac, 260.
" " septum, 259.
Suprascapula, 37.
Suprastapedial, 26, 390.
Suspensorium, 30.
Sylvian aqueduct, 150.
Sympathetic system, 197.
Symphysis pubis, 48.
Systemic arch, 226.
Tactile sensation, organs, 377.
Taste-organs, 380.
Teeth, 278.
Tegmentum vasculosum, 395, 402.
Temporary papillae, 370.
Testis, 341.
Thalamenoephalon, 153.
Thalamus-tubercinereum strand, 154, 155, 159.
Third ventricle, 153.
Thymus gland, 320.
Thyroid gland, 322.
Tibio-femoral septum, 260.
Tibio-fibula, 49.
Toes, 5, 47, 374.
Tongue, 280.
Tonsils, 323.
Touch-corpuscles, 379.
" -spots, 378.
Transverse processes, 17.
Trigeminal nerve, 168.
" nucleus, 145.
Trochlear nerve, 168.
Truncus arteriosus, 216.
Tuberculus maius, 42.
Tympanic membrane, 389.
" ring, 26.
Tympanum, 389, 390.
Upper nasal gland, 386.
Ureters, 337.
Urinary bladder, 338.
" organs, 332.
Uriniferous tubes, 334.
Urino-genital system, 330.
Urostyle, 21.
Utricle, 396.
Vagus, 173.
Valvula cerebelli, 148.
Vasa efferentia, 341.
" recta, 412, 413.
Vein, anterior abdominal, 248.
" " caval, 241.
" " orbital, 245.
" " tibial, 250.
" brachial, 246.
" cardiac, 249.
" caval anterior, 241.
" " posterior, 246.
" cutaneous, 244.
" dorso-lumbar, 248.
" external jugular, 241.
" facial, 245.
" femoral, 249.
" gastric, 249.
" haemorrhoidal, 249.
" hepatic, 247, 297.
" hepatic portal, 249.
" iliac, 247.
" innominate, 242.
" internal jugular, 243.
" intestinal, 249.
" jugular, external, 241.
" " internal, 243.
" lingual, 241.
" mandibular, 242.
" median orbital, 243.
" nasal, 245.
" ophthalmic, 412.
" orbital anterior, 245.
" " median, 243.
" " posterior, 245.
" ovarian, 247.
" oviducal, 248.
" portal, 297.
" posterior caval, 246.
" posterior orbital, 245.
" pulmonary, 241.
" radial, 246.
" renal, 247, 333.
" renal portal, 332.
" sciatic, 247, 250.
" spermatic, 247.
" splenic, 249.
" subclavian, 244.
" subscapular, 244.
" ulnar, 246.
" vertebral, 244.
Veins, 241.
Vena bulbi anterior, 222.
" " superior, 412.
" " posterior, 222.
" spinalis anterior, 164.
" " posterior, 165.
" " superior, 164.
Ventral lymph-sac, 255.
Ventral nucleus, 155.
" septum, 252.
Ventricle of heart, 215.
Ventricles of brain, 153.
" of larynx, 316.
Vertebrae, 16.
" structure of, 20.
Vertebral column, 16.
Vessels of brain, 162.
" of liver, 297.
Vitreous body, 420.
Vocal cords, 315.
" sacs, 320.
Vomerine teeth, 276.
Vomers, 34.
Webs, 5, 275.
Wrist-joint, 45.
THE END.
[Illustration:
The Anatomy of the Frog.
Plate I.
University Press Oxford.
]
[Illustration:
The Anatomy of the Frog.
Plate II.
University Press Oxford.
]
_TRANSLATIONS OF FOREIGN BIOLOGICAL MEMOIRS._
I.
*The Physiology of Nerve, of Muscle, and of the Electrical Organ.*
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*Contributions to the History of the Physiology of the Nervous System.*
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*Essays upon Heredity and Kindred Biological Problems.* By Dr. AUGUST
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