ati ai a = Digitized by the Internet Archive in 2007 with funding from Microsoft Corporation http://www.archive.org/details/comparativeanato0OOchauuoft PREFACE BY THE TRANSLATOR AND EDITOR. Iy undertaking the arduous task of translating and editing the ‘ Traité d’ Anatomie Comparée des Animaua Domestiques’ of M. Chauveau, I have been moved by a desire to fill a void in medical literature which has always existed, so far as the English language is concerned. There has been no complete treatise on the anatomy of the domesticated animals, and the absence of such a work has exerted a serious influence on the progress of veterinary science, and doubtless proved more or less of a loss to the community at large. The only text book to which the student or practitioner of animal medicine could until recently refer, has been that on the anatomy of the Horse, written by the late distinguished army veterinary surgeon, William Percivall, more than forty years ago: a book which, though in every way creditable to its author, was notoriously incomplete, even as regards the anatomy of the only animal it treated of, and was without illustrations. No serious attempt has been made to teach the structure of the other useful creatures domesticated by man, valuable though many of them are; and the student who was anxious to acquire this knowledge had no guide to lead or instruct him. At college, this loss may not have been so severely felt as when, having graduated, he entered on the practice of his profession ; and if the experience of veterinary surgeons in general has been like my own, they will be ready to testify to the almost daily regret they felt at the very meagre notions of anatomy they possessed, and the benefit a complete and trustworthy manual would confer. My professional avocations in the army would not permit me to make the necessary dissections for the production of such a work; and indeed so many classical and standard treatises on the subject have appeared, during this century, on the Continent, and notably in France and Germany, that it would seem a mere waste of time and labour to attempt a task which viii PREFACE BY THE TRANSLATOR AND EDITOR, has been already so thoroughly accomplished by very zealous and pro- ficient anatomists. In selecting for translation the present treatise in preference to other works which are justly held in high estimation, I was influenced not only by the knowledge that it was written by one of the most talented com- parative anatomists and physiologists of the day, but by the ability and originality which are so conspicuous in every page. I was also aware that, for more than a century, the French veterinary schools have been celebrated for the careful and thorough manner in which anatomy has been taught by most efficient teachers, who are all selected by open com- petition ; and that Professor Chauveau’s book was the approved dissection manual of these and other Continental schools, Excellent as was the first edition of the work, the second is still more complete; indeed it may be said to be almost a new book, owing to the assistance afforded by M. Arloing, an anatomist who promises to assume a high rank in his profession. The French treatise is illustrated by three hundred and sixty-eight wood- cuts, but for several reasons it was deemed advisable to select only one hundred and seventy-three from this number: those rejected being chiefly human figures, and either far larger than was necessary or compatible with the space at disposal, or not so well suited for such a work as I was intent on producing. Nearly sixty original figures have been added to those selected; and through the courtesy and liberality of Messrs. J. and A. Churchill, the total number has been increased to four hundred and fifty. The profuseness and general excellence of these drawings, and their great accuracy, will, it is hoped, materially lessen the fatigue and time demanded for the study of this most important subject, and prove valuable for reference to the operator or busy practitioner. No labour or pains have been spared to make the work the most complete and useful of any that has been produced. The best. treatises in German, French, and Italian have been consulted in editing it, and when necessary, I have added to the descriptions. These additions are contained within brackets, thus ( ). As my task has been accomplished without any aid, I assume the entire responsibility for any errors of omission or commission that may exist; my aim being to furnish what has been an urgent desideratum for very many years—a complete dissection manual for the student of veterinary science, a book of reference for the veterinary surgeon, and a work that might be available for the zoologist, comparative anatomist, ethnologist, and medical practitioner. I have for a long time believed that the two branches of medicine—human and animal—should be more closely allied than they are at present, and that this alliance can only be effected by a mutual study and recognition of the facts which prove that the two are really one—wide apart though they have hitherto been kept in this country—and that each is capable of conferring on the other great and lasting benefits. Hence my retaining what constitutes a new feature PREFACE BY THE TRANSLATOR AND EDITOR. ix in the second edition of Chauveau’s treatise—the comparison of the organs of Man with those of ANIMALS. I have omitted from the translation the references made to the Dro- medary and Rabbit; these animals seldom, if ever, coming under the notice of the comparative pathologist in this country. *My grateful acknowledgments are due to my friend and colleague, Professor Chauveau, for the great courtesy with which he not only sanc- tioned the translation now before the public, but offered to supply me with the proof sheets of the new edition as it passed through the press. To the numerous professional friends who pressed upon me the necessity of making such an extensive sacrifice of my few leisure hours, by under- taking a work of this magnitude, I have to express my deep regret at the delay which has occured in its appearance. The fault was not mine : but for the disturbance and abeyance of all business, save that of slaughter, in and around Paris while the book was in course of publication, my task must have been achieved nearly two years ago. I may assure them, however, that the delay has been rather beneficial than otherwise; as it has allowed me to give more time to perfect what might, under other circumstances, have been less complete and satisfactory. GEORGE FLEMING. Brompton Barracks, CHATHAM. February, 1873. a a + er es 4 Mo > iia = ae) mat ¢ * ary th ; P é ’ 4 5 ms - - - . t - 7 hl gat ios iets < ft § Bie sh aciee ‘ar Paine 3 - - 4 7 F me WU, A we . ¢ y 4. . : : ? ; ‘ ‘ e ; ’ : a “4 Ma ¥ = ‘ = - oye ‘ « @ 6 ee ° , . i *,? I * ‘ - ‘ . + a é j ; : AAS OGD ae vy + . 3 it ~ ‘ : — 7 ¥ si * - y oy . Perky a ASS Se ae 2 - » ue . . ‘ — F pe “ “= * , = = _ , . 4 ee ? . 7 af - a fe 29 a ' to * a * * ' . - 4 © nly = .. e 5 . — ; ' *- ; ; — <-> Eg é >, “ . “ ) i PREFACE TO THE FIRST EDITION. To present in a concise and complete form an exact description of the anatomical machinery of which the bodies of our domesticated animals are composed, has been our aim in writing the book now offered for public appreciation. We have sought for concision, not only in language, but also in the choice of facts and ideas, with a kind of stubbornness. In imposing on ourselves this condition, we believe we have rendered a service to those who may have recourse to the book, in economising their time. In an age of progress like the present, when the sciences are becoming multiplied and developed, and when the human mind, seized by the fever of production, gives forth every day books consecrated to the study of these sciences, there is scarcely leisure to read and to learn. It is, therefore, the duty of a writer to be brief. If he loads his book with puerile details; if he says that which may easily be divined by his reader; and if he describes facts and ideas too redundantly; will he have attained the wished-for perfection —in a word, will he be complete? No, he will be tedious: a serious inconvenience, which neither elegance, warmth, nor brilliancy of style will always excuse when met with in a didactic work, and especially in an No effort has been spared to achieve exactitude—the primary desideratum in such a work as this; neither have evenings spent in bibliographic re- searches, nor fatigue in the dissecting-room been considered. All published writings on animal organisation, general treatises, special manuals, mono- graphs, and articles in periodicals have been read and interrogated. But we have more particularly sought for information from Nature—that certain and infallible guide, always wise, even in her diversities ; we have consulted her, scalpel in hand, with a perseverance that nothing could repel. Animals of every kind were had recourse to, and we have largely profited by the immense resources which our position as principal of anatomical teaching in the Imperial Veterinary School has placed at our disposal. xii PREFACE TO THE FIRST EDITION. It was not enough that we should be correct, that we should faithfully describe the organs of the animal economy, It was desirable that the truth might be presented from a high philosophical point of view—one that should rise above details. It is necessary in a book, and especially in one on anatomy, that there should be a salient idea which might indicate its purpose and originality, and distinguish it as something more than a mere arid catalogue, by unifying the thousand different objects of which it treats. In support of this, we would ask permission to explain, in a few words, the idea that presided in the construction of our work. Among the beings or objects composing the natural world, animals are distinguished by diversity in size and external conformation. Is this diversity repeated in their internal structure? When order and simplicity prevail everywhere else in nature, should we expect to find disorder and complication there, or look for as many different organisations as there are particular species? To state these questions, and to resolve them in the affirmative, would be to insult the wisdom of the Creator. The early naturalists, guided by instinct rather than knowledge, admired a certain uniformity in the composition of animals. It was a good inspiration, which threatened to become effaced at the period when anatomical science, diffused and cultivated everywhere with the most laudable eagerness, daily discovered the secrets of the organisation of new species. Without a guide in the search for analogies, struck with the apparent differences their scalpel exposed every moment, the anatomists of that epoch neglected to compare the diverse animals. In presence of a new form of organs, they believed in the existence of a new instrument, and created a new name to designate it. Then was human anatomy, and that of the Horse, Ox, etc., established ; monographs became multiplied; as the different opinions increased, so there was the greater need for a bond to unite these incongruous materials; confusion commenced, and chaos was about to appear; and the principle of analogies was on the point of being buried beneath the ruins of science. Happily, two men appeared, men of genius, who were the glory of France—G. Cuvier and Etienne Geoffroy Saint-Hilaire ; two names which will be for ever illustrious, and which we love to unite as the expression of one and the same symbol. The first, after immense researches, ventured to compare the innu- merable. species in the animal kingdom with each other; he seized their general characters—the analogies which allied them to one another; he weighed these analogies, contrasted them with the dissimilarities, and established among them different kinds and different degrees; and in this way was he able to form natural groups, themselves subdivided into several categories in which individuals were gathered together according to their analogies and affinities. Then the chaos was swept away, light appeared, and the field of science was no longer obscured ; comparative anatomy was created in all its branches, and the structure of the animal kingdom was PREFACE TO THE FIRST EDITION. xiii brought within those laws of uniformity which shine throughout the other parts of creation. Geoffroy Saint-Hilaire followed Cuvier over the same ground. More exclusive than Cuvier, he entirely neglected the differential characters, and allowed himself to be governed by the consideration of resemblances. He especially pursued the discovery of a fixed rule for guidance in the search after these resemblances—a difficult task, and a dangerous reef, upon which the sagacity of his illustrious rival was stranded. To be more certain than Cuvier, and the better to grasp his subject, he restricted the scope of his observations, confining himself more particularly to the class of vertebrata in order to solve the enigma whose answer he sought. At last he found it, and made it known to us in those memorable, though abstruse pages, in which the meaning is often obscure and hidden, but which contain, nevertheless, magnificent hymns chanted to the honour of the Creator. The shape and functions of organs, he says, do not offer any stability, only their relations are invariable; these alone cannot give deceptive indications in the comparison of the vital instruments. He thus founded his great principle of connections, firmly established its value, fortified it by accessory principles, and held it up to the generations to come as a compass, a succourable beacon-light, under whose protection they might proceed to the conquest of analogies with confidence and security. Then was the philosophical sentiment decidedly introduced into the researches in organisation, and anatomy became a veritable science. *Enthusiastically admiring these two great masters, we glory in be- longing to their school; it is, therefore, enough to say that the prevailing idea in our work has been inspired by their labours. Thus, in describing the organs in the somewhat numerous species of animals treated of, and noting their differential characters, we have always endeavoured to demonstrate their analogies. The hopes that Geoffroy Saint-Hilaire entertained for the future of philosophical anatomy have not been entirely realised. Naturalists, it is true, have always cultivated this admirable science ; Lecoq has preserved its traditions at the Lyons Veterinary School, in his simple, lucid, and eleyated teaching ; and at Toulouse, an able and learned professor, Lavocat, has courageously hoisted his flag. But everywhere else, and particularly in the Medical Schools, has not anatomy remained essentially monographic and purely surgical? And many medical men and veterinary surgeons, only looking at the practical side of this science, and full of defiance with respect to speculative theories, will perhaps give us no credit for our efforts in bringing the anatomy of animals into philosophical courses. To these we have nothing to say; if they do not see how much science is developed and becomes comprehensible with such elements; if they cannot under- stand all that is noble and useful in these generalising views; and if they do not feel elevated sentiments revolve in their mind in presence of the simplicity of Nature’s laws, it is because their thoughts are not in unison xiv PREFACE TO THE FIRST EDITION, with ours, and we carefully abstain from engaging in a sterile discussion with them. Such is our plan: have we executed it in a satisfactory manner? We have not deluded ourselves with regard to our strength, and willingly acknowledge that many resources and many qualities have failed us in carrying the enterprise to a favourable termination; therefore we hope to be indulgently judged. If we have succeeded in facilitating the study of so important a subject as anatomy for the pupils of the veterinary schools ; if our book becomes, in the hands of practitioners, a useful surgical guide; if, lastly, medical men and naturalists find that it will assist them in their-researches in com- parative anatomy, our object will have been attained, and we shall haye received the best recompense which the honest writer can hope to obtain. Before terminating, a sentiment of justice and recognition again brings the honourable name of M. Lecoq to our pen; the idea of this book was conceived at his lectures, and it is from these lectures that we have derived the major part of our materials; it was to satisfy the most imperious desire of our heart and conscience that we offered to dedicate this first attempt to him. Could it be better placed than under his patronage ? We have also willingly joined to his name that of M. H. Bouley, that eminent and devoted master, to whose advice we owe so much, and who has evinced the liveliest solicitude for us in circumstances which we can never forget. May he deign to accept this homage as the expression of our sincere recognition. . - We have found in the obligingness and intelligence of M. Rodet a very efficacious aid ; he will permit us to tender all our gratitude. We have frequently put the complaisance of the students around us to a severe test; but they have never failed, and we are gratified in being able to thank them most cordially. We especially mention the name of M. Violet, whose intelligent zeal has spared us much toil in the difficult task imposed upon us. A. Cuauvenav. Lyons, September 30, 1854. PREFACE TO THE SECOND EDITION. Circumstances independent of my will have prevented me from publishing the Second Edition of my ‘ Treatise on Anatomy’ earlier. Those to whom the work is addressed will have lost nothing by the delay, as it has allowed me to procure the co-operation of one of my most distinguished and _best- esteemed pupils. The researches in pathological physiology and experimental medicine, to which I have consecrated my efforts and resources for some years, would have left me no leisure to do more than give a simple reprint of my first edition ; consequently, I must have allowed important omissions to remain, and have renounced the idea of re-casting it according to a new plan I had conceived, even before that edition was terminated. Thanks to the assistance of M. Arloing, who had long before been initiated into my projects, and the details as to their execution which had been present to my mind, this re-casting has been accomplished, and the ‘Treatise on the Comparative Anatomy of the Domesticated Animals’ has thus become an almost entirely new work. I need not attempt to indicate the importance of the modifications and considerable additions that this remodelling has entailed; nor the ame- liorations which the publishers have introduced in the execution of the material portion of the work. It is sufficient to open the book to be convinced of these advantages. A. CHAUVEAU. Lyons, Mareh 15th, 1872, ERRATA. _P. 8,11 linea em btm for endogeeos wie on me P, 168, line 27, for mot prevalent, write eery pr - Tome ‘ mire) - ; ’ -" « « - r . gf ol ~ . H+ F 3 2 PAT J 4 ; ‘ deb ‘ é ‘ « b ~* P < * > ‘ . - i - ! “a my =. =n? . i —_ 5 *% . * ‘ - ‘ é " i eae 4 odie ae ve j we TABLE OF CONTENTS. ———_1oe PAGE ibiatidaice and Editor’s Preface . , : ‘ vii Preface to the First Edition ; - . xi Preface to the Second Edition xv Table of Contents xvii Table of Ilustrations xxxvi GENERAL CONSIDERATIONS. Definition and Division of Anatomy : 1 Enumeration and Classification of the Domesticated Animals . 2 General Idea of the eee of satis and the order followed 3 in studying their apparatus . : 3 BOOK I. LOCOMOTORY APPARATUS, Fimst Secrion.—The Bones . 6 Cxraprer I.—The Bones in tienetal’ 6 Article 1.—The Skeleton . 7 Article m.—General Principles applicable to the Study off all the ‘Bones. 10 Name, Situation, Direction, and Configuration of the Bones 10 Internal Conformation of the Bones. Structure of the Bones 13 Development of the Bones : 16 Cuaprer I1.—The Bones of Mammalia in Particular Article 1.—Vertebral Column : : 18 Characters Common to all the Vertebree : 19 Characters Proper to the Vertebree in each region 21 1. Cervical Vertebree 21 2. Dorsal Vertebre . 24 3. Lumbar Vertebre 25 4. Sacrum . 26 5. Coccygeal Vertebres 27 Of the Spine in General 28 Differential Characters in the Vertebral Column of ‘other than Soliped Animals ; 29 Comparison of the Vertebral Column of Man with that of Animals, 32 Article 1.—The Head ; ; ; - . 33 The Bones of the Cranium 83 1. Occipital 33 2. Parietal 35 3. Frontal 86 xviii TABLE OF CONTENTS. PAGE 4. Ethmoid . 37 5. Sphenoid - 89 6. Temporal 41 The Bones of the Face : ; : , . 1. Superior Maxillary or Great Supermaxillary ; 44 2. Intermaxilla, Incisive Bone, Small Supermaxilla, 0 or Premaxilla ee | 3. Palate : ; : 46 4. Pterygoid ‘ 47 5. Zygomatic ‘ 47 6. Lachrymal 48 7. Bones proper to the Nose, or Supernasl ; j / 48 8. Turbinated Bones. , : ‘ . 49 9. Vomer . : ; ; ; : : 51 10. Inferior Maxillary - ‘ ‘ ; A Mer, | ‘11. Hyoid ; : : : : . 53 Of the Head in General ; ot Differential Characters in the Head of other than Soliped Acuhaaligie 7 55 Comparison of the Head of Man with that of Animals , A . oa Article m1.—The Thorax . 66 The Bones of the Thorax in Partiouler:. 66 1. Sternum of the Horse 66 2. Ribs . : os : f , : : Of the Thorax in General - ‘ 70 Differential Characters in the Thorax of other than Solped Animals ee... 1, Sternum . ; : : 70 2. Ribs . : ; aml i} Comparison of the Thorax of Man with that of Animals ; : 7 1. Sternum ; ; ‘ “ : . eet 2. Ribs ‘ : 2 : : - : 71 Article rv.— Anterior Lambe’ : ; wea, woe ; - oe Shoulder . ; : J F ; ; 72 Scapula ~ 2 Arm. 73 Humerus F 73 Fore-arm 75 1. Radius 75 2. Ulna ; , . e ‘ ; é 76 Anterior Foot . ; ; . , : oe a8 1. Bones of the Carpus : § hy J ; . 78 2. Bones of the Metacarpus ‘ j : ; ‘ye Be 3. Bones of the Digit, or Phalangeal fiegton., 82 Differential Characters in the Anterior Limb of other than Soliped Animals 86 Comparison of the Thoracie Limb of Man with that of the Domesticated Animals ‘ ‘ _ ; . ; ‘ ee Article v.—Posterior Limbs : : ‘ ; ‘ : 91 Pelvis ; ‘ ; ; / ' , : ee? A. Coxe j : : : 4 , : 91 . The Pelvis in G lenioral ; ; F ; , ~ Thigh ; 4 ; pale , : ; ‘ : 98 Femur “ : : ; : . ‘ ; «> 98 : : ‘ ; ; : ? ; é 100 1. Tibia . ; - : : ; : } . 100 2. Fibula : ? : ‘ 3 ; . 101 3. Patella : : : ‘ ‘ ; ; . 102 TABLE OF CONTENTS. Posterior Foot . - 1, Bones of the Taraus 2. Bones of the Metatarsus 3. Bones of the Digital Region Differential Characters in the Posterior Limb of other than. Soliped Animals Comparison of the Abdominal Limb of Man with that of the Domesticated Animals ; Article v1.—The Limbs in Genitenls and their Pasaliclien Cuaprer III.—The Bones in Birds 3 Cuaprer [V.—Theory of the Vertebral Constitution of the Skeleton Srconp Secrion.—The Articulations ; : , Cuarrer I.—The Articulations in General . General Characters of Diarthroses . General Characters of Synarthroses .. General Characters of Amphiarthroses or Spaliphyecs Cuapter II.—The Articulations of Mammalia in Particular Article 1.—Articulations of the Spine F Articulations between the Vertebre, or Tatervaxtsbes! Artioaletines Article n.—Articulations of the Head 1. Atlo-axoid Articulation . 2. Occipito-atloid Articulation . 3. Articulations between the Bones of the Head - 4. Temporo-maxillary Articulation 5. Hyoideal Articulations Article 11.— Articulations of the Thorax 1, Costo-vertebral, or Articulations of the Ribs wits the Vertebral pita 2. Costo-sternal Articulations . 3. Chondro-costal Articulations, or Artiatatione be a the Ribs 4. Articulations between tle Costal Cartilages 5. Sternal Articulation peculiar to the Ox and Pig . The Articulations of the Thorax considered in a seabed manner, with respect to their Movements . Article rv.— Articulations of the Anterior Linbe:. a. 1. Scapulo-humeral Articulation. 2. Humero-radial Articulation Nooure 8. Radio-ulnar Articulation . Articulations of the Carpus . Intermetacarpal Articulations. . Metacarpo-phalangeal Articulations 7 . Articulation of the First Phalanx with the Second, or - first fater- phalangeal Articulation ‘ Articulation of the Second Phalanx with the Third, Redonil Inter. phalangeal Articulation, or Articulation of the Foot Article v.—Articulations of the Posterior Limbs E 2. 3. Articulations of the Pelvis Coxo-femoral Articulation Femoro-tibial Articulation 4. Tibio-fibular Articulation 5. Articulations of the Tarsus, or Hock Cuaprer III.—The Articulations in Birds Turep Seorion.—The Muscles. Onaprer I,—General Considerations on the Btri ped ‘Muscles The Striped Muscles in General TABLE OF CONTENTS. Structure of the Striped Muscles . ~ Physico-chemical Properties of the Striped Muscles : . Physiological Properties of the — Muscles. ; ‘ ; Annexes of the Muscles 7 ; : ‘ Manner of Studying the Muscles . ‘ i 3 . Cuarrer If.—The Muscles of Mammalia in Particular ‘ n ‘ Article 1—The Muscles of the Trunk . ° : ; : Subcutaneous Region . ‘ - : - ” ‘ Fleshy Panniculus : \ é : : : iw Cervical Region ‘ , : ° a. Superior Cervical or Spinal Region of the Neck ‘ be _ SO DWH oP wo Rhomboideus 2. Angularis Muscle of the Seapule : ; : ; : . Splenius . : ; : . . Great Complexus_ ‘ é ‘ alt : . Small Complexus (Trachelo-mastoideus) . y 5 . Transverse Spinous Muscle of the Neck (Spinalis Colli) Intertransversal Muscle of the Neck . Great Oblique Muscle of the Head (Obliquus Capitis Inferior) . Small Oblique Muscle of the Head (Obliquus Capitis Superior) . . Great Posterior Straight Muscle of the Head . 11. Small Posterior Straight Muscle (Rectus Capitis Postions Minor) B. Inferior Cervical or Trachelian Region aR ODe, . Subcutaneous Muscle of the Neck (Pannicalws Carnosus):. . Mastoido-humeralis (Levator Humeri). . Sterno-maxillaris . : ; . Sterno-hyoideus : F . Sterno-thyroideus. ‘ . Omo-hyoideus, or Subscapulo-hyoideus ; . Great Anterior Straight Muscle of the Head (Rectus Capitis Anticus Major) . Small Anterior Straight Muscle of the Head ‘Rectus Capitis Anticus Minor) . Small Lateral Straight Muscle ( (Obliquus Capit Antiou) 10. 11. Scalenus : Long Muscle of the Neck (Longus Coli) . Differential Characters in the Muscles of the Cervical Region of other than Soliped Animals A. Superior Cervical Region B. Inferior Cervical or Trachelian Region Spinal Reg’on of the Back and Loins . Trapezius ° . Great Dorsal (Latissimus Dorsi) " . Small Anterior Serrated Muscle (Superficialis Costaram) , . Small Posterior Serrated Muscle (Superficialis Costarum) . é . Tlio-spinalis Muscle (Longissimus Dorsi) : ‘ . Common Intercostal Muscle (Transversalis Costarum) a 7. Transverse Spinous Muscle of the Back and Loins (Spinalis and Semispinalis Dorsi oor ht Differential Characters in the Muscles of the Spinal Region of the Back and Loins of other than Soliped Animals . Comparison of the Muscles of the Back, Neck, and Cervix i in Man ‘with the analogous Muscles in the Domesticated Animals A. Muscles of the Back and Cervix TABLE OF CONTENTS. B. Muscles of the Neck . Sublumbar or Inferior Lumbar Region : 1, Tliae Fascia or Lumbo-iliac i la nt 2. Great Psoas Muscle. 3. Iliac Psoas Muscle (Lliacus) . 4. Small Psoas Muscle. 5. Square Muscle of the Loins (Sacro-lumbalis) 6. Intertransverse Muscles of the Loins (Intertransverseles Lumborum) Differential Characters in the Muscles of the Sublumbar Region of other than Soliped Animals . Comparison of the Sublumbar Muscles of Man with those of Animals : Coecygeal Region. , . 1. Sacro-coceygeal Muscles ; 2. Ischio-eoccygeus ea Coceygens) Region of the Head . A. Facial Region : 1. Labialis (Orbicularis Oris) 2. Alveolo-labialis (Buccinator) ; 3. Zygomatico-labialis (Zygomaticus) 4. Lachrymo-labial, or Lachrymal Muscle . 5. Supernaso-labialis (Levator Labii Superioris) 6. Supermaxillo-labialis (Nasalis Longus Lebii Superioris) : 7. Great Supermaxillo Nasalis (Dilatator Naris Lateralis) 8. Small Supermaxillo-nasalis (Nasalis Brevis Labii ‘paipewts 9. Transversalis Nasi (Dilatator Naris Anterior). 10. Middle Anterior Muscle (Depressor Labii Superiori) 11. Maxillo-labialis (Depressor Labii Inferioris) . 12. Mento-labialis, or Muscle of the Chin. 13. Middle Posterior Muscle (Levator Menti) B, Masseterine or Temporo-maxillary ——_ 1. Masseter : 2. Temporal or Crotaphitic Muscle , 3. Internal Pterygoid (Pterygoideus Infernus) 4, External Pterygoid : 5. Digastricus . c. Hyoideal Region 1, Mylo-hyoideus 2. Genio-hyoideus 3. Stylo-hyoideus (Hyoideus Magnus) 4, Kerato-hyoideus (Hyoideus me 5. Occipito-styloideus 6. Tranyersalis Hyoidei Differential Characters in the Museles of the Head of other than Soliped Animals : A. Facial Region . B, Masseteriue or Temporo-maxillary Region, c. Hyoid Region Comparison of the Muscles of the Human Head with those of the Domes- ticated Animals. A. Epicranial Muscles B. Muscles of the Face ‘ c. Muscles of the Lower Jaw p. Hyoid Muscles. Axillary Region , xxii TABLE OF CONTENTS. 1. Superficial Pectoral (Pectoralis Transversus) 2. Deep Pectoral ; Differential Characters in the Muscles of the Axillary Region of other than Soliped Animals Costal Region . Great Serratus . . Transverse Muscle of the Ribs (Lateral Sterni ) . External Intercostals ; . Internal Intercostals —. . Supercostals (Levatores Costarum) . . Triangularis of the Sternum (Sterno-costales) : Differential Characters in the Muscles of the Costal Region of other than Soliped Animals . Comparison of the Thoracic Muscles of Man with those ‘of the Domesticated Animals . ‘ ‘ : i ; : Inferior Abdominal Region . Abdominal Tunic . White Line. . Great or External Oblique of the Abdomen . Small or Internal Oblique of the Abdomen . . Great Rectus Muscle of the Abdomen Transverse Muscle of the Abdomen . Differential Characters in the Muscles of the Abdominal Region of other than Soliped Animals - : Comparison of the Abdominal Muscles of Man with those of Animals Diaphragmatic Region ; Diaphragm Differential Characters’ 4 a the Diaphragm of other than Soliped Animals Comparison of the Diaphragm of Man with that of Animals . Article 1.—Muscles of the Anterior Limbs Muscles of tlie Shoulder A. External Scapular Region . External Scapular Aponeurosis . . Long Abductor of the Arm, or Scapular portion of the Deltoid i (Teres Major) . . Short Abductor of the Aro or Tares Minor . Superspinatus (Antea Spinatus) : Subspinatus (Postea Spinatus).. b. Internal Scapular Region 1, Subscapularis 2. Adductor of the Arm, or Peres Major : 3. Coraco-humeralis, Coraco-brachialis, or Omo-brachialis ; 4. Small Scapulo-humeralis . Differential Characters in the Muscles of the Shoulder of other than Soliped Animals . Comparison of the Muscles of the Shoulder of Man with those of Animals Muscles of the Arm. : ; q : a. Anterior Brachial Hegion : 1. Long Flexor of the Fore-arm, or Brachial Biceps (Flexor Brac 2. Short Flexor of the Fore-arm (Humeralis Externus) B. Posterior Brachial Region ; 1. Long Extensor of the Fore-arm (Caput Magnum) 2. Large Extensor of the Fore-arm (Caput Magnum) . 3. Short Extensor of the Fore-arm (Caput Medium) oF whe oO oor an me, oe © SREEES eeEgeeees SSESESESES seeetees 8 sgggeee | ¢ TABLE OF CONTENTS. 4, Middle Extensor of the Fore-arm (Caput Parvum) - 5. Small Extensor of the Fore-arm, or Anconeus Ff Differential Characters in the Mus:les of the Arm of other than Soliped Animals . ° Comparison of the Muscles of the Arm of Man with those of Animals Muscles of the Fore-arm Antibrachial A poneurosis 4. Anterior Antibrachial Betton. 1, Anterior Extensor of the Metacarpus (Extensor Metacarpi Magnus) 2. Oblique Extensor of the Metacarpus (Extensor Metacarpi ae 3. Anterior Extensor of the Phalanges (Extensor Pedis) . 4. Lateral Extensor of the Phalanges peng Suffraginis) B. Posterior Antibrachial Region 1. External Flexor of the Motacarpus, < or Poterior Ulesin, 2. Oblique Flexer of the geome or Anterior Ulvaris ‘(Flexor Metacarpi Medius) : 8. Internal Flexor of the Sideteiaci: or Palnaxis Magnes (Flexor Metacarpi Internus) . 4. Superficial Flexor, Sublimis of the Phalences; or r Perforatus 5. Deep Flexor of the Phulanges, or Perforans J Differential Characters in the Muscles of the Fore-arm of other than Boiped Animals Muscles proper to the Fore-arm i in \ Carnivora . 1. Proper Extensor of the Thumb and Index . 5. Square Pronator. Comparison of the Muscles of the Fore-arm of Man with those of Animals a, Anterior Region , B. External Region . c. Posterior Region é ‘ Muscles of the Anterior Foot or Hand . . A. Muscles of the Anterior Foot in Carnivora 1. Short Abductor of the Thumb . 2. Opponens of the Thumb 8. Short Flexor of the Thumb 4. Adductor of the Index ; 5, Cutaneous Palmar ( Palmaris Brevis) 6. Adductor of the Small Digit 7. Short Flexor of the Small Digit 8. Opponens of the Small Digit 9. Lumbrici : 10. Metacarpal ieiicienion Mustibe d B. Muscles of the Anterior Foot in the Pig c. Muscles of the Anterior Foot in Solipeds Dp. Muscles of the Anterior Foot in Ruminants j Comparison of the Hand of Man with that of Animals A. Muscles of the Thenar Eminence . . B. Muscles of the Hypothenar Eminence. c. Interosseous Muscles ‘ Article 11.— Muscles of the Posterior Limbs ; ; Muscles of the Gluteal Region, or Croup : ; ° 1. Superficial Gluteus (Gluteus Externus) ; xxiv TABLE OF CONTENTS. 2. Middle Gluteus (Gluteus Maximus) d ° 8. Deep Gluteus (Gluteus Internus) . Differential Characters in the Muscles of the Gluteal Region of other than Soliped Animals . : ; Comparison of the Gluteal Muscles of Man with those of Animals . : Muscles of the Thigh 5 ‘ a, Anterior Crural, or Femoral Region ; ‘ 1. Muscle of the Fascia Lata (Tensor Vaginw) ‘ ‘ 2. Crural Triceps : ‘ 3. Anterior Gracilis (Crureus vel Cruralis). B. Posterior Crural Region = 1. Long Vastus (Biceps Abductor Femoris) 2. Semitendinosus Muscle (Adductor Tibialis) 3. Semimembranosus (Adductor Tibialis) . c. Internal Crural Region : 1. Long Adductor of the Leg (Sartorius) 2. Short Adductor of the Leg (Gracilis) 3. Pectineus 4 5. Ce) ey es toe) . Small Adductor of the Thigh (Adduetor Femoris) . . Great Adductor of the Thigh (Adductor Longus) 6. Square Crural (Quadratus $a ; 7. External Obturator 8. Internal Obturator . 9. Gemelli of the Pelvis (Gemini) . Differential Characters in the Muscles of the Thigh of other than Soiped Animals : : a. Anterior Crural Region B. Posterior Crural Region c, Internal Crural Region . Comparison of the Muscles of Man’s Thigh with those of the hist of Animals : a. Anterior Muscles . B. Muscles of the Posterior Region c. Muscles of the Internal Region Muscles of the Leg : ; Tibial Aponeurosis . ; : M A. Anterior Tibial Region : 1, Anterior Extensor of the Phalanges (Extensor Pedis) 2. Lateral Extensor of the Phalanges a eenge’ 3. Flexor of the Metatarsus B. Posterior Tibial Region 1. Gastrocnemii, or Gemelli of ‘the Tibia (Gastroenemi Externus) 2. Soleus, or Solearis (Plantaris) 3. Superficial Flexor of the er or Perforatus (Gastrocnemius Internus) . ; : : : eeee BEESEEZEEESR SERRE SESS gui 4. Popliteus ? 5. Deep Flexor of the Phalanges, 0 or Perforans (Flexor Pedis) . 6. Oblique Flexor of the Phalanges (Flexor Pedis Accessorius) . Differential Characters in the Muscles of the Leg of other than bet> \ Animals : . A. Anterior Tibial Region B. Posterior Tibial Region ° Comparison of the Muscles of the a of Man with ‘those of Anim ils 4, Anterior Region se8e2 222% ee eegeEeNeEsy TABLE OF CONTENTS. 'B. External Region . ©. Posterior Region : Muscles of the Posterior Foot s Comparison of the Muscles of the Foot of Man with those of Animals A. Dorsal Region ; : ; B. Plantar Region ©. Interosseous Muscles , Cuaprer I1.—The Muscles in Birds . Cuaprer [V.—General Table of the insertions of the Muscles i in | Solipeds BOOK II. THE DIGESTIVE APPARATUS, Cuarpter I.—General Considerations on the Digestive cineca Cuarter II.—The Digestive Apparatus in Mammalia Article .—Preparatory ie of the er se rae The Mouth 7. The Mouth in General . Differential Characters in the Mouth of other than Soliped Animals Comparison of the Mouth of Man with that of Animals The Salivary Glands : 1, Parotid Gland . 2. Maxillary, or Submaxillary Gland . 3. Sublingual Gland 4. Molar Glands : 5. Labial, Lingual, and Palatine Glands Differential Characters in the Salivary Glands of other than Sotiped Animals : ‘ Comparison of the Salivary Glands of Man with those of Animals The Pharynx. Differential Characters in the Pharynx of other than Soliped Antinads - Comparison of the Pharynx of Man with that of Animals The Gsophagus ‘ Differential Characters in the CBeophagus of other thant Soliped Animals Comparison of the Esophagus of Man with that of Animals ; Article u.—The Essential Organs of Digestion The Abdominal Cayity P Differential Characters in the Abdominal Cavity of ‘other than 8. ped Animals y Comparison of the Abdominal Cavity of Man with that of Auiinals The Stomach. ; . 1, The Stomach of Solipeds : Differential Characters in the Stomach of other than Soliped Animale 1, The Stomach of the Pig : 2. The Stomach of Carnivora . 3. The Stomach of Ruminants Comparison of the Stomach of Man with that of Aniiials 815 xxvi TABLE OF CONTENTS, The Intestines : 1. The Small Intestine 2. The Large Intestine a. Caecum B. Colon c. Rectum : Differential Characters in the Intestines of other than Soliped Animals . 1. The Intestines of Ruminants é , 2. The Intestines of the Pig 3. The Intestines of Carnivora Comparison of the Intestines of Man with those of Animals j General and Comparative Survey of the Abdominal or Essential Portion of the Digestive Canal. . 418 et Organs Annexed to the Abaoutinal Portion of the Digestive Canal : 419 me 1. Liver ; . ‘ F 5 . 419 i 2. Pancreas . ; - ‘ " i , 427 gq 3. Spleen : 428 a Differential Characters in the Orgar ns Annexed to the Abdominal Portion of - the Digestive Canal in other than Soliped Animals 432 — ae Comparison of the Oigans Annexed to the Abdominal Portion of the Digestive Canal of Man with those of Animals . 3 ; : . 434 Cuarrer III.—The Digestive Apparatus of Birds 435 BOOK III. . eS RESPIRATORY APPARATUS. 7 25 Crapter I.—Respiratory A pent in Mammalia ‘ ‘ . 489 The Nasal Cavities . i ; : 3 ‘ 439 1. The Nostrils : . 440 44 Differential Characters in the Glandiform Bodic: é annexed to the Respiratory Apparatus of other than Soliped Animals ; 474 2. The Nasal Fosse a 3. The Sivuses 446 Differential Characters in the Nasal Cavities of other than Sol! iped Anindls 448 Comparison of the Nasal Cavities of Man with those of Animals é — 449 The Air-tube succeeding the Nasal Cavities : ‘ . 40 1. The Larynx. : ‘ : . ; ' 449 2. The Trachea / 3 , : d ‘ . 457 8. The Bronchi . ‘ 460 Differential Characters in the Airctube ‘gneceeding the Nasal Fosse of other than Soliped Animals . 461 Comparison of the Larynx and Trachea of Man with these Ongons i in the Domesticated Animals é 5 462 The Thorax ; . 462 Differential Characters in the Thorax of other than. Soliped Aniinals ‘ 466 The Lungs : . 466 Differential Characters in the Lungs of other than Soliped Animals ’ 470 Comparison of the Larynx, Trachea, and Lungs of Man with the same : Organsin Animals. . 471 oi The Glandiform Bodies connésted with the Respiratory Apparat : 472 4 1. The Thyroid Body . ; . 472 2. The Thymus Gland. 473 TABLE OF CONTENTS. in Man with those of Animals - E Ouarrer IIl.—The Respiratory Apparatus of Birds BOOK IV. , URINARY APPARATUS. 1. The Kidneys 2. The Ureters 3. The Bladder 4. The Urethra 5. The Suprarenal Capsules Differential Characters of the Urinary Apparatus in “other than Soliped Animals F Comparison of the Urinary Apparatus of Man with that of ‘Aniaeile’ BOOK V. : CIRCULATORY APPARATUS, ‘First Section.—The Heart ' 1. The Heart as a Whole : 2. External Conformation of the iat’ - 8. Internal Conformation of the Heart . 4. Structure of the Heart 5. The Pericardium . 6. The Action of the Heart. Differential Characters in the Heart of other than Soliped Xnisands _. Comparison of the Heart of Man with that of Animals . Seooxp Sxction.—The Arteries : ‘ Cuaprer I.—General Considerations Cuaprer Il.—Pulmonary Artery Cuaprer IiIl.—Aorta . - Article 1.—Common Aorta, or Aortic Trunk Cardiac, or Coronary Arteries Article u.—Posterior Aorta > Parietal Branches of the Posterior Kotte ’ 1. Intercostal Arteries 2. Lumbar Arteries 3. Diaphragmatic Arteries 4. Middle Sacral Artery ; Visceral Branches of the Posterior Arte, 1. Broncho-sophageal Trunk 2. Coeliac Artery . 3. Great Mesenteric Artery 4. Small Mesenteric Artery 5. Renal, or Emulgent Arteries 6. Spermatic Arteries , 7. Small Testicular Arteries (Male), Uterine Artaries (Female) Differential Characters in the Posterior Aorta and its Collateral Branches es of other than Soliped Animals 1. Posterior Aorta in Ruminants 2. Posterior Aorta in the Pig 3. Posterior Aorta in Carnivora Comparison of the Aorta of Man with that of Animals xxvii PAGE Comparison of the Glandiform Bodies annexed to the se wats sen 475 475 xxviii TABLE OF CONTENTS. Article u1.—Internal Iliac Arteries, or Pelvic Trunks ; : ¥ 1, Umbilical Artery . , ‘ S : 2. Internal Pudie, or Bulbous Artery’ ‘ ; : , ‘ - < Subsacral, or Lateral Sacral Artery 3 ; , ; '' 4. Tliaco-muscular, or Ilio-lumbar awn : * x : 5. Gluteal Artery 6. Obturator Artery ; ; ‘ : ; ; 7. Lliaco-femoral Artery : Differential Characters in the Internal Iliac Arte ries of other than Seip d d Animals : 1. Internal Tliace Arteries of Ruminants 2. Internal Dliac Arteries of the Pig 3. Internal [liac Arteries of the Carnivora . Comparison of the Internal Diac Arteries of Man with those of ‘Animals Article 1v.— External Lliac —— or Crural Trunks . : Femoral Artery . : 1, Prepubic Artery 2. Deep Femoral, Deep Muscular, or + Great Posterior Muscular Artery of the Thigh ; “ 3. Superficial Muscular, or Great Anterior Muscular Artery 4. Innominate Muscular, or Small Muscular Arteries . . 5. Saphena Artery Popliteal Artery . : : ‘ Terminal Branches of the Popliteal Artery ; : ° . 1. Posterior Tibial Artery ; ; ‘ ; ; fs 2. Anterior Tibial Artery 3. Pedal Artery Differential Characters in the External Tlic Arteries of oli T than Boliped Animals. : 1. External Iliac Arteries of Ruminants 2, External Iliac Arteries of the Pig 3. External Iliac Arteries of Carnivora Comparison of the External Iliac Arteries cf Man with those of Animals Article v.—Anterior Aorta ; Article v1.—Axillary Arteries, or Brachial Trunks Collateral Branches of the Axillary Arteries . 1. Dorsal, Dorso-muscular, or Transverse Cervical Artery. 2. Superior Cervical, Cervico-muscular, or Deep Cervical Artery . Vertebral Artery . ‘ = . Internal Thoracic, or Internal Mammary Arte Ty . External Thoracic, External Mammary, or Inferior Thoracic Artery . Inferior Cervical Artery 3 . ; . Superscapular Artery . Subscapular Artery } Terminal Branch of the Brachial Trunk, or Humieral Artery. 1. Anterior Radiul Artery . 2. Posterior Radial Artery " 1. First Terminal Branch of the Posterior Radial Artery, or Common Trunk of the Interosseous Metacarpals - 2. Second Terminal Branch of the Posterior Radial Artery, or Colla- teral Artery of the Canon ° : Differential Characters in the Axillary Arteries of Non-soliped Animals 1. Axillary Arteries of Ruminants 2. Axillary Arteries of the Pig . s2a3 2 gg REESEESSSSEESEEE5 nugEseegs SSeeeeee aide TABLE OF CONTENTS. 3. Axillary Arteries of Carnivora . Comparison of the Axillary Arteries of Man with those’ of Animals Article vi.—Common Carotid Arteries Occipital Artery Internal Carotid Artery External Carotid Artery . 1. External Maxillary, Facial, or Glosso-Facial | Artery 2. Maxillo-Muscular Artery . x 3. Posterior Auricular Artery 2 4, Superficial Temporal Artery, or Temporal Trunk 5. Internal Maxillary, or Gutturo-maxillary Artery 1, Carotid Arteries of Carnivora 2. Carotid Arteries of the Pig . 3. Carotid Arteries of Ruminants . Comparison of the Carotid Arteries of Man with those of Animals ; Tuinp Secrion.—The Veins . ‘ Cuarter I,—General Considerations Cuaprter II.—Veins of the Lesser Ginoulstiea, or Polmonary Veins Cuaprer ITI.—Veins of the General Circulation _ Article 1—Cardiac, or Coronary Veins Article 1.—Anterior Vena Cava Jugular Veins ‘ Roots of the Jugular : : 1, Superficial Temporal Vein 2. Internal Maxillary Vein. 8. The Sinuses of the Dura Mater . Axillary Veins . > y 1, Subseapular Vein P 2. Humeral Vein. 3. Spur, or Subcutaneous Thoracic Vein 4. Deep Veins of the Fore-arm 5. Superficial Veins of the Fore-arm 6. Metacarpal Veins 7. Digital Veins . 8. Veins of the Foot, or Ungual Region a, External Venous Apparatus . - b. Internal, or Intra-osseous Venous Apparatus Article 111.—Posterior Vena Cava - } Diaphragmatic Veins Vena Porte . 1. Roots of the Vena Porte ; 2. Lateral Affluents of the Vena Porte Renal Veins ; , Spermatic Veins Lumbar Veins. Common Iliac Veins, or Pelviccrural Trunks 1, Internal Iliac Vein . 2. External Iliac Vein . Femoral Vein Popliteal Vein . . Deep Veins of the Leg ; . Superficial Veins of the Leg . Metatarsal Veins . Veins of the Digital Region. AABMME Differential Characters in the Carotid Arteries of panera Animals xxx TABLE OF CONTENTS. Differential Characters in the Veins of other than Soliped Animals . Comparison of the Veins of Man with those of Animals Fourra Srcrion.—The Lymphatics ‘ ; Cuaprer I.—General Considerations Lymphatic Vessels ° Lymphatic Glands, or Ganglia ‘ Cuaprer Il.—The Lymphaties in Particular Article 1.—The Thoracic Duct Article 1.—The Lymphaties which constitute the Affluents of the Thoracic Duct Lymphatics of the Abdominal Limb; Pelvis, Abdoutba) Parietes, anid Pelvi-inguinal Organs . Sublumbar Glands . ‘ ; é : Deep Inguinal Glands . ; : F ‘ . Superficial Inguinal Glands . Popliteal Glands : . Tliae Glands . Precrural Glands 5 Lymphaties of the Abdominal Viscera > ot i oO NO . Glands and Lymphatic Vessels of the Large Colon . Glands and Lymphatic Vessels of the Caecum ; Glands and Lymphatic Vessels of the Small Intestine . Glands and Lymphatic Vessels of the Stomach ] . Glands and Lymphatic Vessels of the Spleen and Liver . Qo whe Glands and Lymphatic Vessels of the Orguns contained in the Thoracic Cavity ; Glands and Lymphatic Vessels of the Thoracic Parietes_ Lymphatic Vessels of the Head, Neck, and Anterior Limb 1. Prepectoral Glands. 2. Pharyngeal Glands . 8. Submaxillary, or Subglossal Glands. 4, Prescapular Glands : 5. Brachial Glands Article m.—Great Lymphatic Veio Differential Characters in the Lymphaties of Non-soliped Animels , Cuarrer III,—The Circulatory gape tte in Birds Article 1—The Heart. 5 Article u.—The Arteries : Article 11.—The Veins Article 1v.—The Lymphaties BOOK VI. APPARATUS OF INNERVATION. First Secrion.—The Nervous System in General General Conformation of the Nervous System Structure of the Nervous System. Properties and Functions of the Nervous Systems Srconp Secrion.—The Central Axis of the Nervous System Cuaprer L—Protective and Enveloping Parts of the Cerebro-spinal Axis The Bony Case which lodges the Central Se oe Axis 1. The Spinal Canal 2. The Cranial Cavity . Glands and Lymphatic Vessels of the Beetum and Floating Colon: TABLE OF CONTENTS. The Envelopes of the Cerebro-spinal Axis 1, The Dura Mater 3 . _ 2. The Arachnoid ’ 8. The Pin Mater . Cerebro-spinal Axis in other than Soliped Animals , Axis of Man with those of Animals )Qaarrsa Il.—The Spinal Cord . . External Conformation of the Spinal Cord : Internal Conformation and Structure of the Spinal Cord . other than Solipeds 5 _ Comparison of the Spinal Cord of Man enh that of ‘Auiteale - Ouarrer IIL.—The Encephalon ‘ Article 1.—The Encephalon as a Whole Article 1.—The Isthmus . External Conformation of the Isthious 1, The Medulla Oblongata d 2. The Pons Varolii ‘ 83. The Crura Cerebri 4. The Crura Cerebelli 5. The Valve of Vieussens . 6. The Corpora Quadrigemina, or Bigemina 7. The Optic Thalami 8. The Pineal Gland . 9. The Pituitary Gland. Internal Conformation of the isthmus ; 1. The Middle Ventricle, or Ventricle of the Opti Thalami 2. The Aqueduct of Sylvius 8. The Posterior, or Cerebellar Ventricle Structure of the Isthmus. Differential Characters in the Tethmvs of cthes thes Soliped Animals ; Comparison of the Isthmus of Man with that of Animals . Article 111.—The Cerebellum 1, External Conformation of the Cerebellum 2. Internal Conformation of the Cerebellum Differential Characters of the Cerebellum in other than ‘Soliped Animals Comparison of the Cerebellum of Man with that of Animals : Article 1v.—The Cerebrum_ . External Conformation of the Oorebweni:; 1, The Longitudinal Fissure - 2. The Cerebral Hemispheres Internal Conformation of the Brain - The Corpus Callosum_ . The Lateral, or Cerebral Ventricles The Septum Lucidum . . The Cerebral Trigonum (or Forni) The Hippocampi The Corpora Striata . The Cerebral Choroid Plexus, and Velum Toterpesitem . Structure of the Cerebrum - Differential Characters in the Brain of other than Soliped Animals. Comparison of the Brain of Man with that of Animals . NOV Pepe Differential Characters in the Protecting and Enveloping Parts of the Comparison of the Protective and ara Parts of f the Cerebro-pinel Differential Characters in the Spinal Cord of the Domesticated Mammals eiait™ TABLE OF CONTENTS. Pack er Tarep Srotion.—The Nerves Cuarter I.—The Cranial, or Encephalic Nerves 1, First Pair, or Olfactory Nerves 2. Second Pair, or Optic Nerves . ‘ 8. Third Pair, or Common Motor Ocular Nerves 4. Fourth Paix, or Pathetici Nerves 5. Fifth Pair or Trigeminal Nerves . 6. Sixth Pair, or External Motor Ocular Weeves 7. Seventh Pair, or Facial Nerves . 8. Eighth Pair, or Auditory, or Acoustic Nerves q 9 10 il 12 gagage ~~ - o . Ninth Pair, or Glosso-Pharyngeal Nerves . ‘ : . . Tenth Pair, Vagus, or Pneumogastric Nerves ” . Eleventh Pair, Spinal, or Accessory Nerves of the Pneumognstries . Twelfth Pair, or Great Hypoglossal Nerves Differential Characters in the Cranial Nerves of other than Soliped Animals SRZERREE Comparison of the Cranial Nerves of Man with those of Animals . . 744 4 Cuaprer II.—Spinal Nerves : ; i ’ Ce Article 1—Cervical Nerves (Eight Pairs) . ; : - . 748 ‘ Article 1.—Dorsal Nerves (Seventeen Pairs) : : . ‘ 750 3 Article m.—Lumbar Nerves (Six Pairs) 2 7 F 7 . Tae Article rv.—Sacral Nerves (Five Pairs) . ; , E 752 Article v.—Coccygeal Nerves (Six to Seven Pairs) , 753 Article v1.—Composite Nerves formed re the Inferior Ramuscules of the Spinal Branches 78°34 Diaphragmatic Wnrwes : ; : , ‘ . . TSA : Brachial Plexus ‘ P : ; . : 754 1. Diaphragmatic Branches ; : , : . 755 2. Branch to the Angularis and Bhimboldies y P F 755 = 3. Branch to the Serratus Magnus, or Superior Thoracic : > 486 / 4. Branches to the Pectoral Muscles, or Inferior Thoracic . = 756 4 5. Subcutaneous Thoracic Branch ‘ , , ; . 756 a4] 6. Branch to the Great Dorsal ; - ; : , 758 7. Axillary, or Circumflex Nerve : ; P . 758 8. Nerve of Adductor of the Arm, or Teres Major : ‘ : 758 9. Subscapular Branches ; , ‘ . 758 10. Superscapular Nerve. j ; ; ‘ ; 758 11. Anterior Brachial Nerve. - , ; , . 758 12. Radial Nerve . ; : ; . 759 13. Ulnar, or Onbito-sutensons Nerve > f y i . 760 14. Median, or Cubito-plantar Nerve ; 760 Differential Characters in the Brachial Plexus of other than Boliped Animals ; 763 | Comparison of the Brachial Plexus of Man with that of Animals 707 - Sacro-lumbar Plexus ; ; : ‘ . 770 1, Iliaco-muscular Nerves . : : F : 772 2. Crural, or Anterior Femoral Nav 2 ; A : . 772 4 8. Obturator Nerve - : 772 . 4. Small Sciatic, or Anterior and Posterior Gluteal ‘Nerves. ‘ WB 5. Great Sciatic, or Great ea Nerve . , . 774 Collateral Branches : ‘ ; GIS Terminal Branches . 117 Differential Characters in the Secro-lumbar Plexus of other then Scliped Animals 777 Comparison of the Setro-lunber Plexus of Man with that of Animal + _- TABLE OF CONTENTS. _ Onaprer I1L—The Great Sympathetic . . 1, Cephalic Portion of the Sympathetic Chain . < 2. Cervical Portion of the Sympathetic Chain 8. Dorsal Portion of the Sympathetic Chain 4, Lumbar Portion of the Sympathetic Chain 5. Sacral Portion of the Sympathetic Chain Animals Comparison of the Great Sympathetio of Man with that of Animals _ Quarter IV.—The Nervous System of Birds ; : : BOOK VII. APPARATUS OF SENSE. Cuaprer I.—Apparatus of Touch Article 1.—Of the Skin Proper ~ Article u.—The ao sesame Appondages The Hair ; Horny Productions : _ 1. The Hoof of Solipeds . a, The Parts contained in the Hoof | b. Description of the Hoof . : 2. The Claws of Ruminants and Pachyderms 3. The Claws of Carnivora 4, The Frontal Horns 5. The Chesnuts (6. The Ergots . Cuaprer II.—Apparatus of Taste Animals Comparison of the Apparatus of Taste i in Man with that of Animals Cuaprer I1I.—Apparatus of Smell . ‘ n . Cuarrer IV.--Apparatus of Vision . Article 1.—Essential Organ of sew or Globe of the et Membranes of the Eye 1. The Sclerotica . 2. The Transparent Cornea 8. The Choroid Membrane 4, The Iris 5. The Retina ; The Humours of the Eye 1. Crystalline Lens 2. Vitreous Humour 3. Aqueous Humour . Article 1.—Accessory Organs of the Apparatus of Vision Orbital Cavity ; ‘ Motor Muscles of the Globe of the Eye Protective Organs of the Kye 1, Eyelids P 2. Membrana Nictitans Lachrymal Apparatus Animals . Comparison of the Visual Apparatus of Man with that of Animals ‘ ey Differential Characters in the Great Sympathetic of other than Soliped Differential Characters in the — of Taste of other than Soliped = Differential Characters in the Visual Apparatus of other than Soliped xxxiv TABLE OF CONTENTS. Ouarrer V.—Apparatus of Hearing : 2 Article 1.—Internal Ear, or Labyrinth : Bony Labyrinth A . : 1. The Vestibule j . . , 2. The Semicircular Canals ‘ ‘ é . 8. The Cochlea 3 ‘ The Membranous Labyrinth . 1. The Membranous Vestibule ‘ . F 2. The Membranous Semicircular Canals . : é ‘ 8..The Membranous Cochlea . ‘ . Liquids of the Labyrinth . Distribution and Termination of the ‘Auditory N Nerve { in the Messhigaei Labyrinth . ° . . Article 1.—Middle Ear, or Case of the Tympanum ; - Membrane of the Tympanum . The Promontory, Fenestra Ovalis, Fenestra Rotunda d ‘ . The Mastoid Cells . . . Chain of Bones of the Middle Ear . . Mucous Membrane of the rene Case . ‘ Eustachian Tube J ‘ . Guttural Pouches . , ; . > Article m1.—The External Ear . ‘ External Auditory Canal J ‘ . The Concha, or Pavilion 1. Cartilaginous Basis of the Concha : . 2. Muscles of the External Ear . . ‘ 8. Adipose Cushion of the External Ear 4. Integuments of the External Ear , Differential Characters in the Auditory Apparatus of other than Soliped Animals > Comparison of the Auditory Apparatus of Man with that of ‘Aiditints sm pO . BOOK VIII. GENERATIVE APPARATUS, Cuarter I.—Genital Organs of the Male. E PF 5 The Testicles, or Secretory Organs of the Semen . * F 1. Description of the Vaginal Sheath : : 2. Description of the Testicles . Excretory Apparatus for the Semen . 1. The Epididymis and Deferent Duct : 2. The Vesiculz Seminales und Ejaculatory Ducts 3. The Urethra ‘ 4. The Glands Annexed to the Urethral Canal , 5. The Corpus Cavernosum : 6, The Penis . Differential Characters in the Male Genital Organs of other than Soliped Mammals ‘ Comparison of the Genital Organs of Man with those of Animals Cuaprer II.—Genital Organs of the Female 6 1. The Ovaries . 2. The Uterine Cornus, Fallopian Tubes, or Oviduets 83, The Uterus . : . £2 BSkSSSSEREEEEESE ESSESSSS 5843 871 4 SRPRSRREE 28 a ee ee —_—_ > ie OO EE ee ee xe TABLE OF CONTENTS. 4, The Vagina 5. The Vulva . 6. The Mammze Female Animals ; Onarrer IlI.—Generative Apparatus of Birds 1. Male Genital Organs 2. Female Genital Organs BOOK IX. EMBRYOLOGY, Cuaprer I.—The Ovum and its Modifications after Impregnation Article 1—The Ovum Article 1.—Modifications in the Ovum until the Appearance of the Embryo ‘. Article 11.—Development of the Blastodermic Laminz Middle Lamina t : ; “ Internal Lamina . Cuarrer Il.—The Fetal Envelopes of Solipeds 1. The Chorion 2. The Amnion 3. The Allantois . 4, The Umbilical Vesicle 5. The Placenta . 6. The Umbilical Cord . Differential Characters in the ‘Neteoee of the Fostun of other Domgulicated Animals than Solipeds Animals . d Cuapter If —Development of the Fotus Article 1.—Formation of the Embryo : Development of the Chorda Dorsalis and Vertebral Lamine Development of the Lateral and Cephalic Lamine ‘ F Article 1.—Development of the Various Organs of the Animal Heonomy Development of the Nervous System Development of the Organs of Sense Development of the Locomotory Apparatus Development of the Circulatory Apparatus Development of the Respiratory Apparatus Development of the Digestive Apparatus Development of the Genito-urinary Balch Cuarrer IV.—The Ovum of Birds ‘ Index . Comparison of the Annexes of the Human Footus with those of the Foetus of Differential Characters i in the Female Genital Orgens of other than Soliped Mammals . Comparison of the Genital Organs of “Woman with thuse of Domesticated TABLE OF ILLUSTRATIONS. Skeleton of the Dog Skeleton of the Pig . Skeleton of the Horse . Skeleton of the Cow . Skeleton of the Sheep . Vertical section of bone Minute structure of bone Lacunz, or osteoplasts of osseous substance Cartilage at the seat of ossification . Elements of a vertebra . Atlas, inferior surface 12. A cervical vertebra 13. ; 14. Type of a dorsal vertebra, the fourth . Upper surface of lumbar vertebrae . Lumbar vertebra, front view . Lateral view of sacrum . Horse’s head, front view . . Anterior bones of the head of a foetus at birth . Posterior bones of the head of a foetus at birth . Posterior aspect of Horse’s skull : . Antero-posterior and vertical section of the Hoses’ 8 head . Longitudinal and transverse section of the Horse’s head . Inferior maxilla . Hyoid bone . . Lateral view of the Horse’ 8 skull . Ox’s head, anterior aspect . Ram’s head, anterior aspect . Ox’s head, posterior aspect . . Median and vertical section of the Ox's 8 head . Head of the Pig, anterior aspect : * . Head of the Pig, posterior aspect . The axis or dentata, lateral view 83. Head of Dog, anterior aspect . 34. Dog's lead, posterior aspect Front view of the human cranium r . External or basilar surface of human skull . The sternum . ‘ . Typical ribs of the Horse « : . Thorax of Man, anterior face Right scapula, outer surface aa VISSALSSLSSSASASSSSSASENSSRERRESE RS ocwaal 3 Be “". Antero-external view of right humerus _ 42, Posterior view of right humerus _ 48, External face of the radius and ulna _ 44, Right fore-foot of a Horse 3 _ 45. Posterior view of the right carpus 46. Front view of right carpus : 47. Posterior view of right metacarpus 48. Lateral view of the digital region: outside of right limb ‘ _ 49. Posterior view of front digital region . 50. Plantar surface of third phalanx . 51. Navicular bone : 52. Fore-arm and foot of the Ox, feont view 53. Fore-arm and foot of the Dog, anterior face - 54. Human scapula, external aspect . ‘ 55. Right human humerus, anterior surface 56. Human arm bones, front view P 57. Palmar surface of left human hand 58. The Cox, seen from below 59. Pelvis, front view 60. Pelvis, lateral view 61. Left femur, anterior view 62. Left femur, posterior view 63. Section of left femur, showing its structure 64. Posterior view of right tibia 65. Left hind foot, external aspect 66. Left hock, front view 67. Left hock, internal aspect 68. Posterior aspect of left imottarsus 69. Human pelvis, female 70. Right human femur, anterior aspect 2 71. Human tibia and fibula of right leg, anterior aspect 72. Dorsal surface of left human foot . 73. Skeleton ofa Fowl . 74. Cephalic vertebrae of the Dog ‘ 75. Plans of the different classes of articulations : 76. Section of branchial cartilage of oe ape : 77. 78. White or non-elastic fibrous tissue 79. Yellow or elastic fibrous tissue 80. Intervertebral articulations 81. Atlo-axoid and occipito-atloid articulations 82. Temporo-maxillary articulation 83. Articulations of the ribs with the vertebres, upper plane 84. Articulations of the ribs with the vertebra, inferior plane TABLE OF ILLUSTRATIONS. 85. Scapulo-humeral and humero-radial poe sy external face 86. Carpal articulations, front view. 87. Lateral view of the carpal articulations 88. emer tibeerestetionetine pensory ligament 89. Posterior view of metacarpo-phalangeal : and interphalangeal articulations “ 90. Sacro-iliac and coxo-femoral atticaladions . 91. Femoro-tibial articulation . 92. Ligaments attaching the three bones of the leg xxxvii PAGE Original 73 Original 74 Original 76 Original 77 Original 80 Original 80 Original 81 Original 83 Original 83 Original 84 Original 86 Chauveau 87 Chauveau 88 Wilson 89 Wilson 90 Wilson 90 Wilson 91 Chauveau G2 Original 93 Original 9+ Original 99 Original 99 Original 100 Original 101 Original 103 Original 104 Original 104 Original 105 Wilson 108 Wilson 109 Wilson 109 Wilson 109 Chauveau 113 Lavocat 120 Denints and Bouchard 122 Carpenter . 124 Wilson . 124 Carpenter . 125 Carpenter . 125 Chauveau . 133 Chauveau 137 Chauveau 138 Chauveau 140 Chauveau 140 Chauveau 145 Chauveau 150 Chauveau 151 Chauveau 155 Original . 156 Chauveau 161 Chauveau 164 Chaureau . 167 i xxviii TABLE OF ILLUSTRATIONS. =e 93. Tarsal articulations, front view ; . ; . Chauveau . 169 — 94. Articulations of the tarsus, lateral view . ; ‘ Chauveau. VL 95. Ultimate fibril of muscle 7 ‘ : 7 . Bowman . 178 96, Striated muscular tissue fibre : ; ; Bowman . 178 © 97. Termination of nerves in muscular fibre 5 ; . Kithne We 98. Distribution of capillaries i in muscle . ; Berres . 180 4 99. Termination of nerves in an elementary muscular fibre . Beale . 180 | 100. Striated fibre of muscle during contraction : ; Bowman . 181 } 101. Lateral view of the neck, superficial muscles . / Original . 188 j 102, Superficial muscles of the neck and spinal aes of the back Pe | and loins ; Chauveau . 190 | 103. Lateral view of the neck, middle layer of muscles, . Original . 192 } 104. Cervical ligament and deep muscles of the neck . > Chauveau . 194 4 105. Muscles of the spinal mere of the neck, back, and loins . Chauveau . 204 106. Deep ditto : : : ; Chauveau . 207 107. Muscles of the back and cervix of Man ; Wilson =. 210 108. Muscles of the sublumbar, patellar, and internal ermal regions. Chauveau . 218 109. Deep muscles of the sublumbar region : . Chauveau . 214 4 110. Superficial muscles of the face and head . ‘ ; Original . 218 111. Hyoideal and pharyngeal regions . . ‘“ . Original . 226 ‘4 112. Superficial muscles of the Ox’s head F ‘ A Chauveau . 228 4 113. Muscles of the human head. ; : . Wilson . 281 j 114. Muscles of the axillary and cervical regions : ° Chauveau . q 115. Axillary and thoracic muscles - : - . Original . 234 116. Muscles of the inferior abdominal region . ; Chauveau . 2438 | 117. Muscles of the anterior aspect of the body of Man ; . Wilson . 245 4 118. Diaphragm, posterior face ; : = : Chauveau . 247 119. External muscles of the anterior limb ; ‘ . Chauveau . 250 i 120. Muscles of anterior aspect of Man’s upper arm... : Wilson . 25 121. Internal aspect of left anterior limb . . Original . 257° 122. Deep muscles on external aspect of right anterior limb : Original . 260 - 123, Muscles of the fore-arm of the Ox Chauveau . 270 : 124. Tendinous and ligamentous apparatus in the digital region of ; the Ox . : E Chauveau . 271 | 125. Muscles of the fore-arm and paw of the Dog r : . Chauveau . 273 | 126. Superficial muscles of human fore-arm : Wilson . 275 ; 127. Deep layer of superficial muscles of human fore-arm 7 . Wilson . 275 128. Muscles of human hand . : ; Wilson =. 279 129. Superficial muscles of the croup end thigh ‘ Original . 282 130. Muscles of the sublumbar, patellar, and internal crural regions Chauveau . 290 131. Coceygeal and deep muscles surrounding the coxo-femoral . articulation ‘ ~ Chauveau . 293 132. Superficial muscles of the croup end thigh i in the Cow . Chauveau . 294 133. Muscles of the anterior femoral region in Man. Wilson . 296 134, Muscles of the posterior femoral and gluteal region in Man . Wilson 296 135. External deep muscles of right posterior limb . ‘ Original . 299 136. Flexor muscle of metatarsus . : ; . Chauveau . 300 137. Muscles on inner aspect of left posterior limb 3 . Original . 3038 138, External muscles of the leg of the Ox . ; . Chauveau . 307 139. Muscles of the human leg, anterior tibial region , . Wilson =. 810 140, Superficial posterior muscles of the human leg ; . Wilson 310 141, First layer of plantar muscles of human foot i Wilson 312 142. Third, and wo of second pee of pea muscles of human foot : . Wilson 312 195. Section of a leaf of the omasum TABLE OF ILLUSTRATIONS. ory Squamous Sethi from the mouth , f Wilson 144. Columnar epithelium . ; E : , - Kélliker . 145. Columnar ciliated epithelium ; Carpenter . 146. Conical villi on mucous membrane of small intestine Wilson. fe 17. Fuasiform cells of smooth muscular fibre Bowman Hard and soft palate . Chauveau 1 ). Muscles of the tongue, soft palais, and ‘phaiynx ; Chauveau 150. Lobe of racemose gland from the floor of the mouth Kolliker 151. Follicular gland . Kolliker . 152. Median longitudinal section of the ted ind upper part of neck Original . 1538. Section through the fang of a molar tooth Carpenter . _ 154. Transverse section of enamel P : Carpenter . 155. Magnified section of a canine tooth . : Wilson. _ 156. Theoretical section of dental sac of permanent i incisor Chaureau . 157. Section of dentine and pulp of an incisor tooth Carpenter . 158. Dentition of inferior jaw of Horse . Chauveau . 159. Incisor teeth of Horse, details of structure: Chauveau 160. Profile of upper teeth of the Horse ‘ Chauveau 161. Transverse section of Horse’s upper molar Chauveau 162, The teeth of the Ox : ‘ Chauveau 163. Ox’s incisor tooth : Chauveau 164. Incisor teeth of a =e two years old Chauveau 165. Teeth of the Pig Chaureau 166. General and lateral view of the Dog’s tecth ‘ Chauveau 167. Anterior view of the incisors and canine teeth of te Chauveau 168. Section of the human face . Quain 169. Lobule of parotid gland Wagner 170. Capillary network of follicles of parotid gland. Berres 171. Termination of the nerves in the salivary yi Pfhliiger 172. Inferior aspect of head and neck Original 173. Maxillary and sublingual glands Chauveau 174. Pharyngeal and laryngeal region . Original 175. Median longitudinal section of head and upper part of neck Original 176. Muscles of the pharyngeal and hyoideal regions Original 177. Human pharynx , Wilson 178. Transverse vertical section of head and neck Original 179. Pectoral cavity and mediastinum ; Chauveau 180. Theoretical transverse section of abdominal cavity Chauveau 181. Theoretical, lougitudinal, and median section of abdominal cavity . Chauveau 182, The abdominal cavity, with the stomach and other organs. Original 183. Stomach of the Horse . 3 Chauveau 184. Interior of the Horse’s stomach ‘ Chauveau 185. Muscular fibres of stomach. external and middle levers Chauveau . 186, Deep and middle muscular fibres of stomach Chauveau . 187. Peptic gastric gland . : Kiélliker 188. Portion of a peptic cecum Kélliker 189. Mucous gastric gland . Killiker 190. Capillaries of mucous membrane of stomach Carpenter . 191. Stomach of the Dog = Chauveau . 192. Stomach of the Ox F Chauveau . 193. Interior of the stomach « f Ruminants . Chauveau . 194. Section of the wall of the omasum of Sheep Chauveau . After Chauveau xl TABLE OF ILLUSTRATIONS. : Fries. PAGE 196, Longitudinal section of a large papilla from the omasum . Chauveau . 399 197. Villi of human and Sheep’s intestine . ; Teichmann. 403° 198. Portion of Brunner’s gland Thomson . 403 199. Section of mucous membrane of small intestine Teichmann, 404 — 200. Section of mucous membrane of large intestine Teichmann. 405 201. Injected villi of intestine : : ‘ Kolliker . 405 202. Blood-vessels in Peyerian glandule Kélliker . 406 203. Diagram of origin of lactealsin villi . Funke . 406 204. General view of the intestines of the Horse, right side Ae Chauveau 408 205. General view of the Horse’s sahara inferior aspect . Chauveau . 409 ~ 206. The colon of the Horse. ‘ Original . 410 207. Plan of the colon : Chauveau . 411 208. General view of the intestines of the Ox F ; Chauveau . 415 209. Intestines of the Dog . t ° , P . Chauveau. 416 210. Human intestines . Wilson . 417 211. Abdominal cavity, with the liver and other organs Original . 421 212. Portion of a hepatic column, with secreting cells Leidy 423 213. Biliary capillaries and ducts . . . Trminger and Frey 423 214. Blood-vessels in lobules of liver Kiernan 424 215. Section of lobules of Jiver, with intralobuler veins Kiernan 424 216. Excretory apparatus of the Horse’s liver . : Chauveau . 425 217. Malpighian corpuscles attached to splenic artery Kolliker . 4380 218. Splenic corpuscle from the spleen of Ox . ; Killiker 430 219. Liver of the Dog, with its excretory apparatus Chauveau . 433 220. Under surface of the human liver . Wilson . 434 221. General view of the digestive apparatus of a fowl Chauveau . 436 222. Cartilages of the nose ; ‘ Chauveau . 440 223. Transverse section of the head of Fiske Chauveau . 442 224. Longitudinal section of the head, and upper part of neck . Original . 443 225. Cells of the olfactory mucous membrane . Clarke and Schultze 445 226. Fibres of olfactory nerve . : Ecker . 446 227. Superior face of larynx After Chauveau 452 228. Inferior face of larynx ; After Chauveau 452 229. Postero-lateral view of larynx . Original . 454 230. The respiratory organs, inferior aspect Original . 458 231. Ciliated epithelium from the trachea . Killiker . 459 232. Bronchial tube, with its bronchules Heale . 460 233. Mucous membrane of a bronchial tube Heale - 461 234, The pectoral cavity and mediastinum ‘ Chauveau . 463 235. Theoretical section of thoracic cavity, behind the heart Chauveau . 465 236. Theoretical section of thoracic cavity, at root of lungs Chauveau . 465 237. Theoretical section of thoracic cavity, in front of right ventricle Chauveau . 465 238. Plan of a pulmonary lobule Waters . 468 239. Air-cells of lung . Kélliker . 469 — 240. Capillaries and air-cells of lung Carpenter . 469 241. Lung of the Sheep, inferior view . Chauveau . 471 242. Human lungs and heart Wilson . 471 243. Gland vesicles of thyroid Killiker . 472 244. Portion of thymus of calf ; Kolliker 474 | 245. Course and termination of ducts in thymus gland of calf Wilson . 474 = — — s 246. General view of the air-sacs in the duck 247. General view of tle genito-urinary apparatus in the male : Chauveau . 485 248. Horizontal longitudinal section of the Horse’s kidney . Chauveau 487 249. Section of the cortical substance of the kidney Eeker 488 i ee TABLE OF ILLUSTRATIONS. Course of the uriniferous tubuli : ‘ il. Diagram of the circulation in the kidney . . Transverse horizontal section of kidney ; . The kidneys and bladder in the foetus of Solipeds . ca 54. Right kidney of Ox, upper and external face . 155. Left kidney of Ox, internal and inferior face . The calices in left kidney of Ox ’ Theoretical p!an of the circulatory system . _ 258. The heart and principal vessels, left face _ 259, The heart and principal vessels, right face Right side of the heart laid open i , Section of the heart at the level of the valves Left cavities of the heart laid open. Anastomosing muscular fibres of heart 964. Epithelium of the endocardium 265. Human lungs and heart, front view : ae Web of Frog’s foot, showing blood-vessels and tiie hesteunanioa 267. Epithelial cells of blood-vessels p 268, Fenestrated membrane from the carotid artery of the Horse 269, Coarse elastic tissue from pulmonary artery of the Horse ; 270. Transition of a minute artery of the brain into capillary vessels 271. Distribution of the great mesenteric artery 272. Distribution of the small mesenteric artery 273. Arteries of the stomach in Ruminants . 274. Upper and general view of the genitourinary apparatus and arteries in the male 275. Lateral view of the genito-urinary organs in the male ' 276. Abdominal aorta, with its branches, in Man . 277. The external and internal iliac arteries in the Mare . 278. Principal arteries and veins of the posterior foot 279. Anterior aspect of liuman leg and foot 280. Posterior aspect of human leg 281. Arteries of sole of human foot . 282. Distribution of the anterior aorta . 283. Arteries of the fore-foot, seen from behind 284. Arteries of the human fore-arm and hand . 285. Arteries of the brain . é 3 286. Arteries of the head é 287. Réseau admirable of tlie Sheep, seen in profile , 288. Réseau admirable of the Ox, posterior face 289. Arteries of the fuce and head of Man . 290. Roots of the superior jugular vein, with its collateral affluents 291. Section of the cranial cavity and spinal canal =. ‘ 292. Veins of the foot d . ri 293. General view of the veins in the Horse 294. The vena porte and its roots . ‘ 295. Section of a lymphatic rete mirabile 296. Section of lymphatic gland. 297. Section of simple lymphatic gland. 298. Section of the medullary substance of lympnaiio gland of Ox 299. Ordinary disposition of the thoracic duct . B00. Double variety of the thoracic duct 801. Triple variety of the tlheracic duct 802. Lymphatic system of the Horse ‘ , xlii TABLE OF ILLUSTRATIONS. Fries, 803, Great lymphatic vein and entrance of the thoracic duct Colin : 804. Great lymphatic duct, another variety : Colin . 305. Thoracic duct in the Ox . Colin . 306. A variety of the thoracic duct in the Ox Colin : 807. Another variety of the thoracic duct Colin 3 808. A fourth variety of the thoracic duct . Colin 809. Thoracic duct of small Ruminants. Colin s 810. Diagram of structure of nerve-fibre Carpenter . 311. Multipolar, or stellate nerve-cell Ecker ¢ $12. Ganglion from heart of Frog . Ecker 313. Bipolar ganglionic cells and nerve-fibres d Ecker . 814. Stellate nerve-cell . . Beale ‘ 815. Structure of ganglionic cells : Beale and Arnold 316. General view of the spinal cord Colin L 817. Segment of the spinal cord at the cervical bulb j Colin 318. Section of the spinal cord of the Horse at the lumbar region Chauveau . 819. Transverse section of spinal cord of Man at the middle of the lumbar region a I. L. Clarke 320. Longitudinal section through cervical bulb of spinal eand of the Cat : I. L. Clarke 821. General view of the brat: upper pee Oe Chauveau 822. General view of the brain, lower surface Original . 823. Superior view of the encephalic isthmus Chauveau . 324. Lateral view of the isthmus é ‘ Chauveau . 825. Transverse section of the encephalon . ; ; Chauveau . 826. Dissection of the medulla oblongata < Sally and Carpenter $27. Median and vertical section of the encephalon . Chauveau . 328. Section of the cortical substance of the cerebellum . Kélliker 229, Antero-posterior and vertical section of the aaeoe: Chauveau . 830. Corpus callosum . ; Chauveau . 831. Anterior portion of the atonal eendelbles Chauveau . $32. Corticle substance of the cerebral hemispheres Kolliker 333. Base of the human brain ; Hirschfeld and Leveillé 334. Muscular fibres, with termination of motor nerve . Cohnheiin . 835. Nerves of the eye Chaureau 336. General view of the superior ond inferior maxillary nerves Chauveau . 837. Section through the summit of the medulla oblongata .. Carpenter . 888. Origin of the nerves arising from the medulla oblongata . Toussaint. 339. Pneumogastric nerve, with its branches in the neck Toussaint 340. Origin and distribution of the eighth pair of nerves in Man Wilson. 841. Distribution of the nerves in the larynx of the Horse . Toussaint 342. Deep nerves of the head . ¢ é Chauveau . 348. Nerves of the guttural region in the Ox , Toussaint . 344. Nerves of the face and scalp of Man Hirschfeld and Leveillé 345, Distribution of eighth pair of nerves on left side ee and Leveillé 346. Ganglion of a spinal nerve from the spinal region . Kolliker . 847. Nerves of the brachial plexus . ; t Chauveau . 348. External nerves of anterior limb Chauveau . 849. Nerves of the digit of Horse Bouley. 350. Nerves of the digital region of Ruminants . Chauveau . 351. Nerves of the palmar face of Dog’s foot Chauveau . 352. Nerves of the palmar face of Cat’s foot . Chauveau . 353. Nerves of the axilla of Man Hirschfeld and Leveillé . Nerves of the front of forearm and band of Man : Hirschfeld and Leveillé 714 a2 731 r mt gaggeggegegegaas 2 S8gR2228E8RSESEE5 ee we ee Pn ae Sse TABLE OF ILLUSTRATIONS. xiii Lumbo-sacral plexus and internal nerves of posterior limb . “ Chauveau . 771 Posterior portion of the lumbo-sacral plexus : d Chauveau . 773 857. External nerves of posterior limb ; ; . Chauveau . 776 $58. Lumbar plexus of Man . : Hirschfeld and Leveillé 779 859. Nerves at the posterior aspect of homan leg : Hirschfeld and Leveillé 780 860. Nerves at the front aspect of human leg . ’ roe and Leveillé 780 _ 861. Sympathetic ganglion from a Puppy . ' Killiker . 782 _ 862. Sympathetic system of the Horse . y F ; Chauveau . 784 _ $63. Section of Horse’s skin : , : . Chauveau . 793 _ 864. Capillary loops in cutaneous papilis 7 , ; Berres . 798 _ 865. Tactile papille from the skin . ; ‘ ; . Ecker . 794 _ 866. Interungulate gland of Sheep ; : j Owen - 794 _ $67. Branches of cutaneous nerves in skin . ; ; . Ecker = . 795 _ 868. Sudoriparous gland : ‘ j : ‘ Wagner . 795 _ 869. Oblique section of epidermis . : 2 . Carpenter . 796 370. Longitudinal median section of Horse's 's foot f ; Original . 800 371. Horizontal section of Horse’s foot é ia : . Original . 801 372. Lower surface of the Horse’s foot . : d ‘ Original . 802 373. Lateral view of the Horse’s foot ; : é . Original . 808 _ 874. Hoof removed from the foot ; ; . : Leisering . 806 375. Hoof with outer portion of wall removed ; : . Leisering . 806 376. Plantar surface of hoof . : 3 ; , Leisering . 807 377. Horn-cells from the sole of hoof 5 ; ‘ . Leisering . 809 378. Constituent elements of the wall . Leisering . 810 379. Horizontal section of the junction of the wall with the sole of hoof Leisering . 811 380. Horizontal section of wall, and horny and vascular lamin» Leisering . 811 381. Fibres of ultimate ramifications of olfactory nerves. . Ecker . 816 382. Cells of olfactory mucous membrane _—. F Clarke and Shultze 816 383. Theoretical section of the Horse’s eye . Chauveau . 818 384. Anterior segment of a transverse section of the oe of the aye (human) ‘ ‘ Wilson . 821 385. Cells from pigmentum nigrum ; . Carpenter . 822 | 886. The eye (human) with the sclerotic voat removed ; : Holden . 823 387. Muscular structure of the iris . é : . Kélliker . 823 por Vertical section of retina . a : b Miiller - 825 389. Diagram of the structure of the retina : ; . Krause . 826 390. Capillaries in the vascular layer of the retina =. . Berres . 826 / 391. Muscles of the eye-ball, viewed from above. , . Original . 829 392. Section of lamina spiralis of the cochlea . ; “ Carpenter . 838 3 393. Section of the cochlea parallel to its axis - : . Breschet . 838 394. Right tympanic cavity of Horse’s ear . ; ; Chauveau . 841 ; 895. Bones of the middle ear of the Horse . . : . Lavocat . 843 896. Muscles of the ear ; ‘ ; Original . 848 397. Human testis, injected with mercury : ‘ : . Lauth . 854 7 898. Vertical section of the Horse’s testis - : Chauveau . 855 | 399. Internal genito-urinary organs of the foetus of a Mare. . Chauveau . 857 400. Spermatozoa of various animals. : Carpenter . 858 401. Diagram of the testicle : ; . Holden . 859 402. Superior view of the genito-urinary organs Chauveau . 860 403. Longitudinal section of the free extremity of the Horse's penis Chauveau . 866 | 404. Sections of the urethra of the Ox at different points . Chauveau . 868 405. Penis and muscles of the sheath of the Bull . ‘ . Chauveau . 869 406. Section of human pelvis . ; : ; Gray . 871 TABLE OF ILLUSTRATIONS. . Ovarium of the Rabbit J ‘ * ; . Pouehet it. . Constituent parts of mammalian ovum, entire ; ¢ Coste ' SIee . Constituent parts of mammalian ovum, ruptured ; . Coste 875 — . Formation of the corpus luteum. ‘ Z ; Pouchet B75 . Generative organs of the Mare, isolated . : . Chauveau B78 , Generative organs of the Mare, in situ, ; ‘ Chauveau . 881 — . Termination of milk-duct in cluster of follicles 5 . Sir A, Cooper 885 — . Ultimate follicles of mammary gland, with secreting cells . Lebert 885 — . Microscopie appearance of milk ; ; : . Funke 885 . Human uterus, with its appendages : ; Wilson 888 . First stages in segmentation of mammalian ovum . Coste . SOV 418. Later stages in segmentation : Coste - 801 419. Section through embryo of the Chick, first gc of incubation Kélliker . 898 420. Plan of early uterine ovum Wagner . 894 421. Diagram of ovum at formation of the amnion . Wagner . S804 422. Exterior of the chorial sac, Mare . ; Chauveau . 895 423. Fecundated egg, showing formation of amnion and allantois Dalton 896. 424, Fecundated egg, with amnion nearly completed Dalton . 896 425. Foetus of the Mare, with its envelopes. r Chauveau 898 426. Portion of ultimate ramifications of umbilical veescls. Carpenter . 899 427. Portion of one of the foetal villi Ecker 900 — 428. Equine foetus, opened on left side to show umbilical veasels Chauveau . 901 429. Blood-vessels in liver of an equine foetus at mid-term . Colin . 902 430. Liver of a Lamb at birth . Colin . 902 481. Diagram of an early human ovum Wagner . 904 432. Diagram of a human ovum in second month Wagner . 904 433. Early stages in the development ofa Fowl . Husley . 906 434. Transverse section of embryo of Chick on third day Kolliker . 908 435. Plan of development of eye Kolliker . 909 436. Origin of encephalic centres in human emtthitys: of vith week Wagner 910 437, Plan of chorda dorsalis at period of formation of embryo Kolliker 912 438, Plan of vertebra at an early period of development Kolliker 912 439. Head of a footal Lamb, showing Meckel’s cartilage Hurley . 918 440, Plan of first system of vessels, embryo. — Kolliker . 914 — 441. Embryonic heart at an early period, anterior view Killiker 915, 442. Ditto, seen from behind " Kolliker . 915 443. Heart of an equine foetus . : Chauveau . 916 444, Plan of the aorta and its arches at an early period: Kolliker . 97 445. Plan of the circulation in the human embryo, side view Coste 918 446. First appearance of the lungs . " Wagner 919 447. Embryo of Dog at twenty-five days ‘ Bischoff 919 448. Origin of liver from intestinal wall of embryo Chick Miiller 922 449, Urinary and genital apparatus in rae Chick Miiller . 922 450. Section of Fowl's egg . Allen Thomson 925 THE COMPARATIVE ANATOMY OF THE DOMESTICATED ANIMALS. GENERAL CONSIDERATIONS. DEFINITION AND DIVISIONS OF ANATOMY, Anatomy is the science of organisation; it studies the structure of animated beings when these have been deprived of life. It comprises two grand divisions: physiological anatomy, which describes healthy organs, and yical anatomy, whose object is the description of diseased organs. Physiological anatomy, in its turn, embraces :— 1. General anatomy, which is occupied with the analogous matters or tissues of the animal body, with regard to their texture, and their physical, chemical, and physiological properties, irrespective of the organs in which these tissues exist. The particular study of the anatomical elements entering into the composition of the tissues is named histology. 2. iptive anatomy, which studies the situation, form, and relation of organs, as well as the relative arrangement of the various tissues composing them, with the exception of the structure and properties of these tissues. ' If this study be devoted to a single species, it is designated special , anatomy. Example: human anatomy, or anthropotomy ; the anatomy of the Horse, or hippotomy. When descriptive anatomy embraces the study of the organisation of the entire animal kingdom, and examines the differences which characterise the same organ or the same series of organs in each class, family, genus, or species, it is named comparative anatomy. Restricted to the domesticated animals, this study constitutes veterinary anatomy. Philosophical or transcendental anatomy differs from comparative anatomy, inasmuch as it indicates the analogies of organs or apparatus, in order to exhibit the simplicity of Nature’s plan in the general laws of organisation. Finally, if descriptive anatomy is limited to denoting the relations existing between the various organs of a region, particularly with a view to the performance of operations and the diagnosis of external diseases, it takes the names of topographical, regional, or surgical anatomy. B A a ek ee *4 2 GENERAL VONSIDERATIONS. ENUMERATION AND CLASSIFICATION OF THE SPECIES OF DOMESTICATED —~ ANIMALS, The object of this book is the study of veterinary anatomy. The animals of which it treats belong to the mammiferous class and to that of birds. The domesticated mammals of our regions have their representatives in a large number of orders. Thus, we find among them :— 1. Of the carnivora, the Dog and Cat ; 2. A rodent, the Rabbit ; 8. A pachyderm, the Pig ; 4. Of solipeds, the Horse and Ass ; the produce of the male ass with the mare, i.e., the Mule, and that of the horse with the female ass, known by the name of Hinny ; 5. Of ruminants, the Ox, Sheep, and Goat. With regard to poultry, they range themselves :— 1. In the gallinaceous order, the genera to which the common fowl, — guinea fowl, turkey, and pigeon belong ; ' 2. In the order of palmipeds, the geese and ducks. Girard has proposed a special classification for the domesticated mammals, based upon the number of digits terminating each of their limbs, and has defined four categories: the first comprises the horse, ass, mule, and hinny,- which take the name of monodactyles, because their digital region is composed of a single digit; in the second, under the denomination of didactyles or _ bisulcate animals, those with two digits, such as the ox, sheep, and goat; in’ the third, or regular tetradactyles, is found ranged the pig, each of whose limbs shows four digits; lastly, the dog and cat, which most frequently have four digits on the posterior members and five on the anterior ones, and form the class of irregular tetradactyles. This nomenclature will not be followed here, as it is opposed to the general laws of organisation ; philosophical anatomy has, in fact, demonstrated that there are really no veritable monodactyles, didactyles, ete., all are materially or virtually pentadactyles. It is therefore considered better to keep to the classification established by zoologists, because it prevents confusion in scientific language, which should always be the same for everyone engaged in the study of anatomy. : The regimen and habits of the domesticated animals bring about differ- ences in their organisation which appear very great at first sight, though in reality they are not so profound as they seem, In order to study the descriptive anatomy of all these animals, we will not pass them in review, one after another, giving for each the description of every organ; but shall take a type, which will most frequently be the Horse, and briefly compare all the others with it. In the majority of cases, we will describe, without leaving the Horse, all the organs of an apparatus ; afterwards the same organs in the other species will be studied in the same order. In this comparison, the animals will be generally classed according to their domestic value; though exceptions will be made to the rule which has been instituted by our predecessors, whenever any advantage in point of concision or perspicuity is likely to be obtained. > — ee solids. GENERAL CONSIDERATIONS. 3 GENERAL IDEA OP THE ORGANISATION OF ANIMALS. Order followed in studying the Various Apparatus. The bodies of animals, formed of organised matter, contain fluids and The fluids are very abundant in the animal economy; not only do they fill certain vessels constructed for them, but they also impregnate all the solid parts of the body. Their importance is very great, for without them the organic solids would perish; an element deprived of humidity is an element deprived of life. Fluids vary in their nature and composition. Apart from those that the solids imbibe, there is not one which is completely amorphous. In the midst of a liquid holding organised matter in solution there are always elements which will be referred to hereafter. Examples : the blood and lymph. In studying the organic solids, we will proceed from the simple to the complicated. ‘ Exements.—Solid organised matter presents itself in the form of more or less voluminous particles, in every instance invisible to the naked eye, and named the anatomical elements. They may be reduced to three principal : the granule, cell, and fibre. Granules.—These are the smallest known elements. They may be held in suspension in animal fluids, remain free among the other elements, or be enclosed in the interior of cells. Their nature is not always the same: they are proteic or fatty. They are called pigmentary when they exhibit a brown colour. Cells.—The cell is pre-eminently the anatomical element. It may be represented to the mind as a microscopic collection of a nitrogenous substance, viscid or slightly granular, and endowed with extreme vitality. Frequently in the midst of this protoplasm (for so it has been called), there is perceived a nucleus provided with a nucleolus, and at its periphery an enveloping membrane is discovered. It must not be forgotten that this membrane, and even the nucleus, is necessarily a constituent portion of the cell. The cell lives like an entire organism: it feeds, grows, multiplies, absorbs, secretes, moves, etc. It behaves like a complete animal, though it be a microscopic one, The form of the cell varies greatly, as does its volume and its nature. Tt has therefore received various names. There are round, polyhedral, fusiform, stellate, and other shaped cells. Some have a diameter of 1-12000th part of an inch, while others are 1-2000th part. Cells multiply in various ways: 1st, by the division of the nucleus and segmentation of the protoplasm in the interior of the enveloping membrane (endogeneous multiplication); 2nd, by constriction, the division of the nucleus, protoplasm, and enveloping membrane ( fissiparous multipli- cation); 3rd, by a kind of bulging or swelling of the enveloping membrane, and strangulation and separation of the enlargement thus formed _(gemmation ). A large number of cells only temporarily remain in this condition. In consequence of modifications that cannot be referred to here, they are con- verted into fibrille or other elements, in which it is difficult to recognise them. Others maintain the cellular form: then they are developed, live, and die in several ways. Sometimes they are worn by the contact of foreign ; B 2 4 GENERAL CONSIDERATIONS. bodies, as on the surface of the skin; at other times they become dissolved, as in some glands; finally, at other periods they submit to fatty degeneration, which gradually brings about their complete destruction. The permanent cells have been arranged according to the following denominations :— 1. Hematies or red globules, which are found in a state of suspension in the blood; they are round or elliptical. . Leucocytes, or white globules, which float in the blood, lymph, and ehyle. . Connective cells, comprising the connective cell properly so-called, the plasmatic cell, and the adipose cell. . Medullary cells, forming the principal elements of the marrow of bones (myeloplaxes and medullo-cells). . Contractile cells, which constitute the basis of muscular tissue. . Nerve cells, met with in the cerebro-spinal centres and the ganglia of the cerebro-spinal and sympathetic systems. . Epithelial cells, comprising the epithelial cells properly called, situated on the surface of the skin and mucous membranes, and the glandular cells. Fibres.—A fibre is an elongated anatomical element, of variable dimensions and composition. It may be very fine and represented by a single line, or thicker and marked by two lines more or less apart from one another. It is homogeneous throughout, or the contents are distinct from the enyelope. The vitality of fibres is not to be compared with that of cells; after they are formed, they can only be nourished, and cannot multiply of themselves. In the animal economy four kinds of fibres are distinguished :—the connective Jibre, elastic fibre, muscular fibre, and nervous (or nerve) fibre. Tissurs.—The elements that have now been rapidly described, in becoming united and grouped in different fashions, form the tissues, Some tissues are composed of one kind of element; these are the simple tissues. Example :—The epithelium. The majority, however, are formed by the union of several different elements: these are the composite tissues. Example :—Nervous tissue. It is also remarked that there are tissues in which exists a fundamental intercellular substance, and others in which this is absent. The latter are few in number, for the vessels and nerves may, in certain tissues, be considered as intercellular substance. The anatomical, physico-chemical, and physiological characters of the tissues repeat, as might easily be inferred, the anatomical, physico-chemical, ‘and physiological properties of the elements entering into their formation. Only four fundamental tissues are recognised, basing them on the morphological, chemical, and physiological characters of the elements. In the first place, the tissue of the conjunctival substance should be noticed ; this, in consequence of some differential characters, may be divided into :— gelatinous tissue, conjunctival (or connective) tissue, cartilaginous tissue, and bony tissue. Then comes the cellular tissue, formed entirely of persistent cells. It comprises the epithelial tissue and the glandular tissue. The cells of the epithelial tissue may affect different arrangements. If they are disposed in a single row, there results a simple epithelium ; if they are superposed it is a stratified epithelium. According to the form of the cells of the superficial layer, the epithelium is polyhedral, pavement, cylindrical, or spherical, In certain points, these superficial cells are furnished with vibratile filaments ; they are then designated vibratil: (or ciliated) epithelium. ~J So or — Co bo GENERAL CONSIDERATIONS. 5 In the third place, is the muscular tissue, which may be divided into _ striated and non-striated (or striped, and non-striped or smooth) fibres. Lastly comes the nervous tissue, which offers two aspects: the white and grey substance. The first is entirely formed by nerve fibres, and the second fibres and nerve cells. © Onreans.—The term organ is given to an agglomeration of tissues anaweg a determinate form, and having a function tv fulfil. Organs are ore composed of tissues, as the tissues themselves are constituted by anatomical elements. All animal organs are enclosed between two membranes named limitary or tegumentary membranes, which are continuous with one another at the margin of the natural openings. ‘These are the skin and the mucous membranes, in whose composition is included a layer of connective tissue covered by an epithelium. Organs are distinguished into those which are solid, and those which are hollow. Among the first, a certain number act as supports: such are the organs formed by the connective tissue, and particularly the cartilages and bones. ' Others are destined to produce movements: these are the two kinds of muscles. The action of the muscles is communicated directly to the organs that are to be moved, or it is transmitted through the medium of other organs, such as the tendons and aponeuroses. The central nervous organs; nerves. properly so called, and the vaseular glands, belong to this group of-solid organs. - With regard to the hollow organs, they are everywhere covered by the internal, tegumentary, or mucous membrane. Examples:—the lungs and stomach. There must also be included the vessels formed by elastic and contractile membranes arranged as canals, in which tlie blood and lymph circulate ; and, lastly, the serous membranes, which line the interior of the splanchnic cavities, and cover the surface of the organs contained in thei. Apparatus.—Organs are very numerous in the animal economy, and in order to study them profitably it is necessary to classify them in a methodi- cal manner, according to their physiological affinities. Consequently, there have been collected into a single category all those organs which are destined to achieve the same physiological finality, and to such a group has been given the name of apparatus. An apparatus is, then, an assemblage of all those organs of an animal which concur to the same end, and which serve for the accomplishment of the same function. We will successively describe, in the following order, the different appa- ratus of which the organism is composed :— - = ++ ~~,” , Lecomotory Apparatus ; . Digestive Apparatus ; Respiratory Apparatus ; Urinary Depurative Apparatus ; Circulatory Apparatus ; Innervatory Apparatus ; Sensory Apparatus ; Generative Apparatus ; DNS Sm pol This description will be terminated by a brief exposition of the evolution of the foetus and its appendages, C6 j BOOK I. LocoMoToRY APPARATUS. Tux locomotory apparatus is composed of all those organs which minister to the movements an animal may execute. It is certainly one of the most im- portant in the economy, from the number and volume of the pieces which enter into its formation, and by the necessary co-operation that it affords the other apparatus in the performance of the physiological acts which are allotted to them. It is constituted of two kinds of organs; the bones and muscles. The bones, hard and resisting, stony in appearance, are real inert levers, joined to each other by firm and movable articulations, which permit their playing upon each other with the greatest facility, at the same time maintaining them in their relative positions. The muscles, grouped around the bones and attached to them, are soft organs which possess the property of contrac- tion, under certain determinate conditions, and of involving in that move- ment the bones to which they are fixed by their extremities. The first are altogether passive in their motion, while the second are really the active organs of locomotion—the powers intended to move the bony levers. We will treat successively of :— 1, The study of the bones, a particular branch of descriptive anatomy which has received the name of osteology ; 2. The study of the articulations, or arthrology ; 3. The study of the muscles, or myology. FIRST SECTION. THE Bones. CHAPTER IL THE BONES IN GENERAL. Bones, properly speaking, are only to be found in vertebrate animals, and constitute their principal zoological character. In the animal body they form an internal framework which consolidates the entire edifice, and gives it its general form and dimensions. It is advantageous, before commencing a particular description of each bone, to survey them in a general manner, This study comprises: 1, The description of the skeleton ; 2, The summary indication of the general principles which should be known in order to com- prehend the details of the special descriptions. THE SKELETON, 7 Articte I.—Tue SKELETON. The whole of the bones, considered in their natural relations to each other, constitute the skeleton. In order to prepare the skeleton of any animal, it is sufficient to free it from the soft parts surrounding it. The skeleton should be designated natural, if in this operation the ligaments Wy Ss ay sy» SKELETON OF THE PIG, 3 THE BONES. that naturally join the various pieces together are allowed to remain ; and artificial if, after these ligaments have been destroyed, it is necessary to rep them by materials foreign to organisation, such as iron or brass wire. The skeleton is divided into trunk and limbs. The trunk offers for consideration, in the median line, the spine or vertebral column, a flexible stalk measuring the entire length of the animal, and composed of a series of distinct pieces articulated one behind the other. Anteriorly, this stalk supports the head, a pyramidal protuberance which itself results from the assemblage of a large number of bones. On each side of the middle portion of the spine, there are detached bony Fig. 3. Gy ERR IA NS MUU e LD my Wy SKELETON OF THE HORSE. | arches which have received the name of ribs, and which rest, directly or indirectly, by their inferior extremities, on a single bone called the sternum. These bony arches in this way circumscribe the thoraa, a spacious cavity destined for the reception of the principal organs of re- spiration and circulation. The limbs, four in number, two anterior and two posterior, are the appendages which support the trunk, Each represents a column divided into several rays resting upon one another, and generally forming more or less acute angles. The anterior limbs are each divisible into four principal regions: the shoulder, applied against the front part of the thorax ; the arm, which succeeds the shoulder; and the fore-arm and foot. The posterior limbs also comprise four regions: the hawnch or pelvis, which articulates with the posterior part of the spine; and the thigh, leg, and posterior foot. ; THE SKELETON. 9 In birds, the posterior limbs alone assume the function of columns of support. The anterior limbs, formed for flight, constitute the wings. ae — — Se SKELETON @F THE COW. SKELETON OF THE SHEEP. The number of bones entering into the composition of the skeleton of the domesticated animals, arrived at the adult period of life, varies according 10 GENERAL PRINCIPLES APPLICABLE TO to the species. They are apportioned to the regions of the trunk and limbs just mentioned, in the manner indicated in the following table : DESIGNATION. Solipeds.! | Ruminants.| —_Pig. Dog.2 Vertebral Column® . . .| 44 43 42 48 Heed‘... 5 kak: ae eee 28 29 28 Whiwaxs, |. 5 (5 a ee 27 29 27 Shoulder . ) (|; 1-2 1-2 1-2 1-2 Arm. . 1-2 1-2 1-2 1-2 rack side | aban | ote | of ore-foot . : 8 0 | 36-72 | 36-72 Pelvis, ¢ Double regions ) | “45 13) 71-358", dae Thigh . 1-2 1-2 1-2 1-2 Leg. . 8-6 3-6 3-6 8-6 Hind-foot } (| 15-80 19-88 | 86-72 | 82-64 Artiote Il.—Gernerat Princietes APPLICABLE TO THE STUDY OF ALL THE Bones. The description of any bone comprises its name, situation, direction, conformation, structure, and mode of development. Name. The nomenclature of osteology does not rest on any basis capable of conferring upon it a methodic form. Consequently, we find bones which derive their name from their shape, (example: the fibula); others from their resemblance to known objects (the tibia and vomer). Some owe it to their position (cétes, sides or ribs), or their uses (the axis and parietal — bones). Several attempts have been made to submit the nomenclature of the bones to more precise and uniform rules, but the new designations proposed have not been sanctioned by custom. Situation. The situation of a bone should be viewed in two ways: 1st, Relative to the median plane of the body ; 2nd, Relative to the other portions of the skeleton. A. Situation relative to the median plane of the body. The designation of median plane, or improperly median line, is given to an imaginary vertical plane, passing through the middle of the skeleton which it divides, from before to behind, into two equal portions. The bones may be situated on the median plane, in which case there is only one of each kind, and they are called single; they are also named symmetrical bones, because the median plane divides them into two equal lateral halves exactly alike, The bones disposed in a double and regular manner on the sides of the median plane bear, for this reason, the name of pairs; they are also called asymmetrical bones, because their form does not admit of their being separated in any sense into two similar portions. On the contrary, a bone of this kind always offers the most perfect symmetry with its fellow on the opposite side. ' One lumbar vertebra less is found in the ass, and sometimes also in the mule, 2 The os penis has not been included. 3 The sacrum is reckoned as a single bone, and the number of coccygeal vertebra at an average of 12 for the Horse, 16 for the Ox, 14 for the Pig, and 15 for the Dog. * The os hyoides comprises, and is reckoned as, a single bone, — Se THE STUDY OF THE BONES. 11 B. Relative situation to the other parts of the skeleton —To indicate the _ situation of a bone, considered from this point of view, is to make known the a0 it oceupies in the region to which it belongs, and the connections it may have with adjoining regions. Thus the radius is situated in front of the ulna, between the arm-bone and the carpus. Direction. This is absolute or relative. The direction of a bone may be vertical, . horizontal, or oblique. Example: the scapula is placed in an oblique direc- tion from above to below, and from behind to before. Configuration of the Bones, Form.—This is also absolute or relative. A. Absolute Form.—The absolute form of a bone is that which it owes to the relations existing between its three dimensions—length, width, and thickness. a. A bone in which one of its dimensions much exceeds those of the other two is a long bone. Example :—the femur. All the long bones are hollowed out internally by an elongated space—the medullary cavity. Long bones belong exclusively to the limbs. In the animal economy, there are found bones which resemble them in their dimensions, but they have no medullary canal, Example :—the ribs. These differ essentially from the true long bones, and are sometimes distinguished from them by the appellation of elongated bones. b. A bone that offers two dimensions much more developed than the third, is a flat or wide bone. Example:—the parietal bone. The bones of this category, destitute of a medullary cavity, are met with in the head and the upper regions of the limbs. ¢. A bone which offers nearly the same development in all its dimensions, is called a short-bone. Example :— the astragalus. Destitute, like the preceding, of a medullary cavity, the short bones are found in the spine and some regions of the limbs. B. Relative Form.—To make known the relative form of a bone is to indicate the greater or less exact resemblance it may bear to geometrical figures, or to familiar objects. Thus the scapula is a bone of a triangular form. | | Exrernat Pecuniariies or Bones.—These markedly attract the atten- tion, because they modify the general shape of bones, and singularly assist us in distinguishing one bone from another. These peculiarities, which are real distinctive features that permit their description to be precisely esta- blished, are always either eminences (processes) or depressions. Eminences.—The eminences that stand out in relief from the surfaces of bones are divided into two different categories. One class concurs in the formation of the articulations which join the bones to each other; they are named articular eminences, in which, again, are distinguished diarthrodial and ial eminences, according as they belong to movable or immovable articulations. ‘The others, usually destined for the insertion of ligaments and muscles, are called non-articular, or eminences of implantation. (The term imprint is also used in anatomy, and signifies a collection of small rugged eminences which make the surface of the bone uneven and rough. There are muscular, tendinous, ligamentous, and aponeurotic im- prints, according as they give attachment to muscles, tendons, ligaments, or uroses. The synarthrodial eminences are always indentations more or less deep and finely cut. 12 GENERAL PRINCIPLES APPLICABLE TO The diarthrodial eminences are voluminous and smooth, and in a fresh state are covered with cartilage. They are named heads and condyles: heads, when they describe the segment of a sphere (head of the femur, head of the cores? condyles, when they represent the segment of an oval figure, cut parallel to its large axis (condyles of the femur.) ty The non-articular eminences receive various names. If they are volumi- nous and much detached from the bone, they are called processes or apophyses. Apophyses receive qualificatives derived from the analogies perceived between them and known objects. (Examples :—the styloid, clinoid, coronoid an coracoid processes.) The appellations of protuberances and tuberosities — are given to non-articular eminences when they are large and round, and but slightly prominent. Lastly, they are named lines, crests, and ridges, when they are narrow and very long. Cavities.—The cavities of bones have also been divided into articular and non-articular cavities, — The first correspond to the eminences of the same name in the bon joints. They take the designation of cotyloid cavities when they are deeply excavated, like a basin or the cup of an acorn (the glenoid cavity of the scapula, and the cotyloid cavity of the coxa). The non-articular cavities serve either for ligamentous or muscular implantation, or for the passage of vessels, nerves, tendons, etc. They are termed channels or furrows, when they are wide, deep, and smooth ; grooves, when they are long, narrow, and even at the bottom ; Jissures, when they are narrow and rough. Digital impressions is the name given to those excavations in bones which look as if produced by the pressure of the finger. The fosse, sinuses, cells, and notches are also non- articular cavities of bones. The sinuses and cells are formed by open spaces in the interior of bones; notches, by cavities excavated on their wargins. When a cavity passes quite through a bone it is termed a foramen. If this foramen offers a certain length, it is then designated a conduit or canal. Fissures are long, narrow foramina; hiatus is the term applied to wide openings with irregular outlines. ReGions oF THE Bonrs.—When it is desired to describe the eminences and external cavities of a bone, it is essential not to notice them, as it were, by chance—passing indifferently from one to another. In order to avoid the difficulties which would result from the application of such an irrational system, it is convenient to divide the bone to be described into several regions, in which are examined, one after another, all the external peculiari- ties that may offer. The following is the course to pursue in order to establish the regions of a long, a flat, and a short bone. (a) A long bone is always divided into three parts: a body and two extremities. The body, middle part, or diaphysis, is the narrowest portion of the bone. It represents a geometrical solid, approaching more or less the figure of a very elongated prism. In a long bone, therefore, it is necessary to study as many faces, angles, or borders, as the prism it represents may offer. . With regard to the extremities, or epiphyses, these are more or less con- siderable enlargements, showing articular surfaces, as well as surfaces intended for muscular or ligamentous insertion. ' (b) A flat bone must necessarily have two faces, as well as borders and angles, THE STUDY OF THE BONES. 13 (c) A short bone offers for description a variable number of faces, and or ent angles, which are often neglected because of their trifling Internal Conformation of Bones. _ Sections made in various directions through the substance of bones show that their internal conformation varies, according as they belong to the eategory of long, flat, or short bones. The diaphysis of long bones is hollowed out into a large fusiform cavity; this is the medullary canal. _ This canal is absent in the flat and short bones. Its walls are formed by a sa dense bony tissue, whose pores are scarcely visible to the naked eye, hich is called the compact substance. The extremities of long bones are surrounded by a thin layer of compact substance, while. the remainder of their mass is constituted by the spongy substance—bony tissue channeled into cells, or very large areole, which freely communicate with each other. (Reticulated bony tissue is but another form of spongy substance, the only difference between the two consisting in the cells or meshes of the first being formed of intercrossed osseous fibres, while those of the second are formed of lamelle.) The medullary canal, and areole of the spongy tissue, are filled by a cellulo-fatty substance, the marrow (or medulla). The flat bones are constituted by a layer of spongy tissue placed between two lamine® of compact substance. In the flat bones of the cranium, the two layers of compact tissue are termed the vitreous tables, while the cells of the spongy tissue are designated diploé. In certain points of their extent, the spongy substance disappears, and then the bone is found to be composed of a single lamina of compact tissue. The short bones have a nucleus of spongy substance, enveloped in a layer, more or less thick, of compact tissue. The compact substance of the bones being very resisting, is found in all those situations which have to sustain violent efforts. The spongy substance is very light and bulky, and is met with in the widened portions of the — to which it affords increased size without adding sensibly to their weight. Structure of Bones. Bones are formed of a proper tissue, covered externally by a particular membrane, the periosteum, and occupied internally by the medulla; vessels, aud nerves. Proper tissue. —The texture of the proper tissue of bones varies slightly in the compact and spongy substance. The compact tissue is composed of a funda- mental substance, which is amorphous, or slightly granular, white, and more or less opaque, accord- ing to the thickness it offers. This fundamental substance is penetrated by an infinite number of vascular canaliculi, known as the Haversian canals. These canals, which measure from 1-2500th to 1-200th of an inch in diameter, are parallel to each other and to the larger axis of the bone; they frequently com- municate by transverse branches. The most | ~ - superficial open on the surface of the bone, be- hoteles whe” uesmuee tak neath the periosteum, and the deepest into the — Haversian canals. 14 GENERAL PRINOIPLES APPLICABLE TO medullary canal; while a certain number terminate in the areole of the spongy substance. The walls of these canals are constituted by several concentric lamelle ney of fundamental substance, and in af ie the body of these are lodged the essential elements of the bony tissue, or osteoplasts (corpuscles or lacune). These are minute cavi- ties lined by a cellular membrane, and furnished, at their cireum- ference, with a great number of canaliculated prolongations, which communicate with the adjacent osteoplasts, or with the Haversian - canals, In a thin dried section of bone, the osteoplasts a black by transmitted light, and white and brilliant by direct light ; MINUTE STRUCTURE OF BONE, as shown ina thin t¢hig appearance has led some ob- ea ee Poss bass to the direction of the servers to suppose that they were 1, A Haversian canal surrounded by its concentric formed of small MASSES of calea- lamellw; the lacune are seen between the la- reous matter. It is now well melle, but the radiating tubuli are omitted; known that they are minute 2, Jbid, with its concentric lamin, lacune, and ramifying cavities, lodging a cell radiating tubuli; 3, The area of one of the -; . ‘ert canals; 4, 4, Intervening lamella, and between impregnated with liquid. them, at the upper part, several very long In the spongy texture no lacune with their tubuli. Haversian canals can be seen ; the osteoplasts are irregularly Fig. 8. disposed in the thickness of the fundamental substance, which con- stitutes the septa of the areole of this tissue. As a rule, the proper tissue of the bones is composed of a frame- work of organic matter which has gelatine for its base, and in which are deposited the calcareous phos- phates and carbonates, which give to this tissue its characteristic hardness, This is easily rendered evident by immersing any bone in dilute nitric or hydrochloric acid ; acids dissolve the calcareous salts, but do not act upon the organic framework. So it is that, after some days’ maceration, the bone becomes flexible, like cartilage, and loses part of its weight, although it preserves its volume. The counterpart of this experiment may be made by submitting it to the action of fire. It is then rendered quite friable, because its organic skeleton has been destroyed without the earthy salts it contained being affected. Periostewm.— This is a very vascular and nervous fibrous membrane that covers the entire bone, with the exception of the articular surfaces. Its thickness and adherence are not the same everywhere. By its inner face it corresponds to the surface of the bone; by its external face, it is confounded with the insertion of the tendons and ligaments, or with the surrounding connective tissue. LACUN2, OR OSTEOPLASTS OF OSSEOUS SUBSTANCE, magnified 500 diameters. a, Central cavity; }, Its ramifications, ———————— = ee S—~—‘“‘=—a wr THE STUDY OF THE BONES. 15 _ The periosteum may be resolved into two layers, though these are not very distinct. The superficial layer is essentially fibrous, and is formed by a mixture of connective and elastic fibres and plasmatic cells. The deep layer also contains a loose connective tissue, but more especially elastic fibres, and more or less voluminous spherical or fusiform cells. This is called the osteogeneous layer. Medulla.—The medulla, or marrow, is a pulpy, fatty substance, which fills the medullary canal and the areole of the spongy tissue of the bones. Somewhat consistent, and of a rose tint in the bones of the young animal, the marrow becomes diffluent and yellow in the bones of those advanced in age. Tn the first instance, it only contains traces of fat; while in the second it has 96 per cent. of this substance. The medulla of bones is composed of: 1st, Some trabecule of delicate connective tissue, which serves to support the vessels and nerves; 2nd, Fat either free or inclosed in vesicles; 3rd, Particular cells, named by M. Robin medullo-cells and myeloplazes. The medullo cells, abundant in the red or foetal marrow, are small cells with a spherical nucleus; while the myeloplawes are large, flattened, or polyhedral elements of an irregular outline, containing a great number of nuclei. Rare in the yellow marrow, they are more particularly found adhering to the walls of the medullary canal, or the alveoli of the spongy tissue. 4 s.—The arteries of bones belong to three orders ; a distinction founded on their volume and the extent of their distribution. The arteries of the first order penetrate to the interior of the medullary canal of long bones by a particular orifice, the nutritious foramen. They soon divide into two branches, which break up into a network that lines the walls of the canal and enters the tissue of the medulla. This network communicates with the arteries of the second order, which are destined to the spongy tissue of the extremities of the long bones, penetrating them by the numerous nutritious foramina that surround the epiphyses. Lastly, the arteries of the third order are branches of the periostic network which enter the superficial Haversian canals. These canals which open in this manner on the surface of the bones may be considered, strictly speaking, as a third category of nutritious conduits. In the flat and short bones there are no arteries of the first order. Veins accompany the arteries, and are always more voluminous than these; they frequently make their exit by special and very large openings at those points where the spongy tissue is abundant. The veins of bones sometimes exhibit saccular dilatations on their course. Certain veins in the cranial bones have their parietes entirely composed of osseous tissue. Lymphatic vessels—The existence of these in the interior of bones cannot be affirmed. Nerves.—These belong to the cerebro-spinal and ganglionic system of nerves ; the latter are always vaso-motory nerves, Almost constantly a somewhat voluminous nerve enters the medullary canal by passing through the nutritious foramen, and is distributed to the medulla. The compact tissue receives few nervous filaments; while, on the contrary, the spongy tissue at the extremities of the long bones, as well as the short bones, obtains an abundant supply. Certain short bones, such as the vertebre, are especially remarkable for the numerous nerves they receive. 16 GENERAL PRINCIPLES APPLICABLE TO DEVELOPMENT OF BONES. Bones, before arriving at the state in which they present themselves in — the adult animal, pass through several successive phases, whose study consti- tutes what is termed osteogeny. In the embryo, at a very early period, the bones are com of a mucous material analogous to that which enters into the composition of. all the other organs; this matter is constituted by a mass of what are called embryonic cells, Ata later period they are impregnated with gelatine, and nearly all become harder, white, and elastic, passing into the cartilaginous” state. Exception must be made, however, to the lateral and anterior parietes of the cranium and the face, the bones of which are at first fibrous but never cartilaginous. The cartilaginous bones show a fundamental amorphous substance, in which are disseminated spherical cells containing one or more nuclei. This condition is transitory ; the cartilaginous tissue soon submits to modifications which result in conferring on the pieces that it composes the hardness and structure of perfect osseous tissue. Thbse modifications constitute the process of ossification. There are several portions of the skeleton which do not undergo this osseous transformation, and which most frequently remain in the cartilaginous condition during the entire life of the animal. These permanent cartilages are met with at those points where the bony skeleton must preserve a certain degree of flexibility, and on the articular surfaces. During the process of ossification, the cartilages become vascular, are impregnated with calcareous salts, and excavated with Haversian canaliculi and medullary cavities. The saline molecules are deposited in the amorphous substance, which grows more hard and opaque ; at the same time the cartilaginous cells become the point of departure of a new embryonic proliferation, from which results the neoplasts. Ossification begins at the same time in several parts of the skeleton, and in each of the bones in particular; though it does not appear over the whole extent of the latter at once; on the contrary, in certain determinate points of the cartilaginous mass, bony tissue can be perceived developing itself and extending gradually until it finishes by completely invading it. These points are called centres of ossification. These centres are primary or complementary ; the latter are in some way added to the bone, and form, wholly or in part, certain processes. Although these centres of ossification enlarge from day to day, yet for a somewhat long period they remain completely independent of one another, and are only connected by cartilaginous tissue. The term epiphyses is given -to the osseous centres which are placed at the extremities of the principal centre. When the skeleton is completely developed, the various centres of ossification are fused into each other, and then there are no longer epiphyses ; this fusion always takes place at an almost determinate epoch. It has been remarked that, of two epiphyses, it is con- stantly the cne near which the nutritious foramen is directed that is first united to the body of the bone. Growth.— Bones grow in width and thickness by the apposition of new elements. In the long bones, the growth in length takes place by the ossification of the cartilage uniting the epiphyses to the body of the bone. Consequently, elongation should cease as soon as the epiphyses are incor- porated with the diaphysis. With regard to the long bones of the limbs, Duhamel, Flourens, and particularly MM. Ollier and Humphry, have remarked that, in the thoracic limb, the extremity furthest removed from ' THE STUDY OF THE BONES. “V7 the humero-radial articulation grows fastest; while in the abdominal limb, the extremity most distant from the femoro-tibial articulation grows the least. ing the growth of the bones in thickness, this occurs by the ossifi- cation of the deep layer of the periosteum called the osteogenetic layer. The ts of the above-named authors have irrefutably demonstrated this _ faet. The formation of bony tissue in the deep layer of the periosteum is very active during the youth of animals; but it soon slackens, and in advanced age ceases completely. In the first period of life, in proportion as the new Inger are added to the surface of the bone, the old layers, those nearest the medullary canal, disappear by resorption. Later, the process of resorption exceeds that of formation, which is, in old age, completely annihilated. It has also been observed that the formation of a certain quantity of the osseous elements takes place on the inner face of the medullary canal, at the expense of the medullary tissue. In the flat bones, the primitive centre of ossification is developed nearly in the middle, and the calcareous salts are afterwards deposited in radiating lines from this spot towards the periphery. These bones are augmented in thickness by the formation of subperiostic layers, and by the development of the spongy tissue between their two compact lamine; they increase in width by the ossification of what are termed the marginal epiphyses. The short bones grow from the periosteum and the ys othgetd - ee when they possess complementary centres. Nutrition, —The experiments which consisted in feeding young animals with madder, and afterwards examining their osseous system, have for a long period demonstrated the nutrition of bones. When bones cease to grow, their nutri- tion becomes less active; but it is evident that it does go on, in order to maintain the organic matter of the osseous tissue in a proper con- dition. _ (Professor Owen has explicitly and concisely stated the development of bone to occur as fol- lows :—* The primitive basis, or ‘ blastema’ of bone is a transparent glairy matter containing humerous minute corpuscles. It progressively acquires increased firmness ; sometimes assuming a membranous or ligamentous state, usually a gristly consistence, before its conversion into bone. The change into cartilage is noted by the appearance of minute nucleated cells, which increase in number and size, and are aggregated ae with intercellular tracts, — the cation is about to begin, as in fig es eahiat” oa These rows, in the cartilaginous basis of ““ossiricarios, showing at its long bones, are vertical to its ends; in that of lower portions the clusters flat bones they are vertical to the margin. The of cells arranged in columns, cells furthest from the seat of ossification are “ih of which js inclosed in a flattened and in close contact ; nearest that seat a bstance. they become enlarged and separated. The first appearance of bone is that of minute granules in the inter- columnar and intercellular tissue. Canals are next formed in the wae by 18 THE BONES. absorption, which ultimately receive bloodvessels, and become the ‘ vascular canals.’ The immediate nutrition of bone is provided for by the production of minute ‘ plasmatic canals’ from the vascular ones. When these canals become dilated, so as to offer definite forms, they are termed ‘lacunw’ or * bone-cells,’ and to some extent characterise, by their shape and size, the osseous tissue of the respective vertebrate classes. In the concentrie lamine surrounding the vascular canal, the bone-cells or osteoplasts are arranged concentrically, between the laminw, with the long axis in the direction of the circular line of the plate. Most of the plasmatic tubes con- tinued from the bone-cells pierce the plates at right angles in their course to the vascular canal, with which they communicate; and they form the essential vehicle of the material for future growth. Extension of parts, however, is not the sole process which takes place in the growth of bone; to adapt it to its destined offices, changes are wrought in it by the removal of parts previously formed. In marine creatures, the bones usually remain — solid; but in the active land quadrupeds, the shaft of the long bones is hollow, the first-formed osseous substance being absorbed, as new bone is being deposited without. The strength and lightness of the limb-bones are thus increased after the well-known principle of the hollow column. The bones of birds present this quality in the highest degree, particularly those of — powerful flight. In these the medullary cavity of beasts is transformed into a capacious cavity containing rarified air instead of marrow. In the mam- malian class, the air-cells of bone are confined to the head, and are filled from the cavities of the nose or ear, not from the lungs, as in birds. Such cells are called ‘frontal sinuses, ‘antrum,’ ‘sphenoidal,’ and ‘ ethmoidal.’ The frontal sinuses extend backward oyer the top of the skull in the rumi- nant and some other quadrupeds, and penetrate the cores of the horns in oxen, sheep, and certain antelopes. The most remarkable development of cranial air-cells is presented by the elephant, the intellectual physiognomy of this large quadruped being caused, as in the owl, not by the actual capacity of the brain-case, but by the vast extent of the pneumatic cellular structure between the outer and inner plates of the skull-wall. All these varied changes in the osseous tissue, from mere cancelli to large medullary or pneumatic cavities, are the result of secondary changes by absorption, and not of the primitive constitution of bones, which were at first solid.”) CHAPTER II. THE BONES OF MAMMALIA IN PARTICULAR. Articte I,—VerrresraL Cotumn. Tnx vertebral column, or spine, is a solid and flexible stalk situated in the middle and upper part of the trunk, of which it forms the essential portion. It protects the spinal cord and sustains the thorax, as well as the principal organs of the circulation, respiration, and digestion. Articulated anteriorly with the head, and terminating in a point at its posterior extremity, this piece is formed by a somewhat considerable assemblage of short, single, tuberous bones, to which has been given the name of vertebre. These THE VERTEBRAL COLUMN. 19 bones, though all constructed on an uniform type, yet do not offer the same tion throughout the whole rachidean stalk, The differences they "present into this respect, have allowed of their being formed into five prin- groups; whence the division of the vertebral column in five regions, ch are, enumerating them from before to behind: 1, Cervical region ; i Dorsal region ; 3, Lumbar region ; 4, Sacral region ; 5, ” Coceygeal region. The first comprises seven vertebra, which serve as a ‘pase for the animal's neck: the second has eighteen, against which the ribs are placed ; the third has only six, which correspond to the loins ; in the fourth there aro five, constantly solidified into one mass in the adult, to constitute a single bone— _ the sacrum ; while the fifth possesses a variable number of small degenerate vertebra, gradually decreasing in size to form the tail. The pieces consti- tuting the first three regions are called true vertebre ; those if the last two are designated false vertebre. The characters belonging to all these vertebre will be first studied ; then a particular description of the vertebre of each region will be given; and, finally, an examination will be made of the spine as a whole. CHARACTERS COMMON TO ALL THE VERTEBRA. Each of these small bones is pierced from before to behind by a wide Fig. 10. ; a r ELEMENTS OF A VERTEBRA: AFTER OWEN. 7 ; A, Ideal typical vertebra; 8, Actual thoracic vertebra of a bird; e, Centrum (or : body), giving off, d, d, the diapophyses, and p, p, the parapophyses (transverse and . articular processes) ; the neural arch, inclosing the spi cord, is formed by B. n, n, the neurapophyses (/amine), and n, 8, the neural spine (spinous process) ; the hwmal arch, inclosing the great ceutres of the circulation, is formed by A, A, the hemapophyses (costal cartilages); and h, s, the hemal spine (sternum). From both the neurapophyses and hemapophyses may be given off the zygapophyses, z, z The lateral arches, which may inclose the vertebral arteries, 0, 0, are ‘ ' completed by the pleurapophyses (ribs), pl. ; these in B are bent downwards, 80 ; as to form part of the hamal arch, and give off the diverging appendages, a, a. opening, the spinal foramen ; whence results, for the entire spine, a long canal traversing its whole length, and which lodges a very important c 2 20 THE BONES. portion of the nervous centres—the spinal marrow. This canal, which traverses the vertebra from one end to the other, transforms it into a veritable ring in which we recognise, for facility of description, two parts— the one inferior, the other superior. The first, or body, is very thick, and forms the base of the vertebra; the second, which is thin, has been de- signated spinous or spinal, from one of the peculiarities it presents, or annular, because it circumscribes the major portion of the spinal foramen. This division is not altogether an arbitrary one, for the body and the annular por- tion constitute, in the fetus, two distinct pieces, which do not become united for a long time after birth. Bopy.—The shape of the body of a vertebra is that of a prism with four faces, of which two only—the superior and inferior—are free, and can be studied in the adult; the two lateral faces being united and confounded with the annular portion. This prism also presents two extremities—an anterior and posterior. Faces.—The superior face, limited in extent, forms part of the spinal foramen, constituting its floor. It exhibits: 1, On the median line, two roughened, prominent surfaces, representing two triangles, whose summits are opposed; 2, On the sides, two depressed smooth surfaces, perforated by one or more openings that lead to the interior of the bone. The inferior face is divided into two lateral portions by a median crest. Extremities.—The anterior has a prominent convex head, more or less detached. The posterior offers a cavity for the reception of the head of the next vertebra. These two planes, the one convex, the other concave, do not come into immediate contact; an elastic, flexible fibro-cartilage, firmly attached to each, being interposed between them. Annuar Portion.—This is formed by an osseous plate that curves sud- denly downwards, in the shape of an arch, the two extremities of which approach each other, inclose the body, and become united to it. It offers for study: 1, An internal and an external surface; 2, An anterior and a posterior border. Surfaces,—The internal surface, concave and smooth, forms, with the superior face of the body, the spinal foramen. The external, convex and irregular, presents: 1, A single prominence, raised in the middle of the superior portion, and named the spinous process ; 2, The transverse processes are a double pair of eminences, one on each side, and projected transversely outwards. 7% Borders.—The anterior border has two articular facets looking upwards: these are the anterior articular processes, right and left. In each is a notch which, when placed in opposition to a similar excavation in the preceding vertebra, forms the intervertebral foramen. The posterior border presents the same peculiarities, with this difference, that the articular faces of the terior articular proresses are inclined downwards, to correspond with the anterior facets of the succeeding vertebra. Structure of the vertebre.—The compact substance, which is abundant in the spinous portion, forms, in the body, an extremely thin layer, inclosing a voluminous nucleus of spongy tissue. The latter is traversed by numerous venous canals, which open on the surface of the bone. Development.—It has been already shown that the body and spinous portion of a vertebra constitute, in young animals, two distinct pieces. Each was primarily formed from two lateral centres, which met on the median line. In the body, the fusion of these centres is so prompt, that it is generally believed, perhaps justly, that the development of this part of the vertebra THE VERTEBRAL COLUMN. > 21 eee from a single centre of ossification. The union of the two centres the annular portion, usually designated the vertebral lamina, is slower. It commences in the most anterior vertebra, and is latest in the sacral and coceygeal regions. To the two principal pieces of the vertebra in process of ossification, is added, at a subsequent period, complementary points of ossifi- cation, five or six in number: one or two for the spinous process, one for the suinmit of each transverse process, another for the head, and the last for the posterior cavity of the body. CHARACTERS PROPER TO THE VERTEBRZ OF EACH REGION, - A casual inspection of a vertebra might suffice, strictly speaking, to dis- tinguish the region of the spine to which it belonged. For instance, a cervical vertebra is recognised by its volume, the absence of a spinous aN and the foramen which traverses the base of its transverse processes. ‘he dorsal vertebra is conspicuous by its tubercular transverse processes, and by being furnished, outwardly, with an articular surface, as well as by the depression on its body destined to receive the heads of the ribs. The lumbar vertebra has its long flattened transverse processes; while the coecygeal vertebra offers rudimentary laminz and processes. There is no necessity for noticing the sacrum, whose five pieces form one bone: a feature which markedly distinguishes it from the other regions of the vertebral column. But these few distinctive characteristics do not satisfy the require- ments of descriptive anatomy; so that it is necessary to undertake a more extensive study of each of these regions. 1. Cervical Vertebre. Geyerat Cuaracters.—These vertebra, the longest and thickest in the spine, present generally a cubic form. They are usually distinguished from the vertebre of the other regions by the following characters :—The inferior spine of the body is strongly marked, especially behind, where it terminates in a small tubercle. The head is well detached from the re- mainder of the bone, and describes a very short curve. The posterior cavity, wide and deep, represents a veritable cotyloid depression, which is too large to fit the head exactly; the intermediate fibro-cartilage on these two surfaces is also of a great thickness. The spinous process forms a simple roughened, and but slightly prominent, ridge. The transverse processes, very developed, are elongated in an antero-posterior direction, and inclined down- wards. In this region they are designated the trachelian processes, because of their relations with the trachea; a foramen that traverses them from before to behind at their base has been, for the same reason, named the trachelian foramen (vertebral foramen). The articular processes, large and einen, are inclined downwards and inwards. The notches are wide and p- Spzorrtco Cuaracters.—The seven cervical vertebree are reckoned from before to behind, and receive numerical names indicating their place in the on. S* Ficst._-'The first vertebra of the neck, which has been named the aélas,' deserves a very careful description. At first sight there is recognised the ? So named frum the mythological personage who was supposed to support the eart!, as the first vertebra (human) supports the head. (For this bone in the domesticated animals the name is nut appropriate.) 22 7 THE BONES. great development of its transversal diameter, the considerable dimensions of the spinal foramen, and the thinness of its body. The intra-rachidian face of the latter is divided into two portions by a transverse ridge: one anterior, furnished with ligamentous imprints, exhibits, laterally, two d excavations, which lodge the venous sinuses; the other, posterior, is smoo and concave from side to side, and forms an articular surface into which is received the odontoid process of the axis; this surface resembles the cotyloid cavity. The inferior spine of the body appears as a large tubercle. The head is absent, and is replaced by two concave facets. The anterior articular processes have their gliding surfaces looking downwards ; they are joined to the two preceding facets to constitute two large diarthrodial cavities, which correspond to the occipital condyles. There is no spinous process, but a rough- ened surface instead. The transverse pro- cesses are large, flattened above and below, incline forwards and downwards, and are provided with a thick rugged lip. Pos- teriorly, quite at their base, and on each side Fig. 11. ATLAS; INFERIOR SURFACE. 1, Articular processes for condyles of the occipital bone; 2, ibidem; 3, Vertebral or antero-internal fora- men; 4, Posterior, or cervical fora- men; 5, Transverse process; 6, Tubercle representing the inferior spinous process; 7, Superior arch, forming the roof of the spinal fora- men. Fig. 12. A CERVICAL VERTEBRA, 1, Superior spinous process; 2, An- terior articular processes; 3, Pos- terior articular processes; 5, An- terior convex face of body; 6, 7, Transverse processes, with . their tubercles or rudimentary ribs; 8, Inferior crest, or spine; 9, Concave posterior face. from six centres of ossification of the spinal foramen, they show two large vertical facets which represent the posterior articular processes; these facets are uneven, are confounded with the articular cavity of the upper face of the body, and correspond to the two analogous facets of the axis. Each transverse process is pierced at its base by two foramina, which traverse it from below upwards. The posterior repre- sents the vertebral foramen of the other ver- tebre ; while the anterior is continued to the external surface of the process by a wide, deep, but very short channel, running from without to within, and joins a third fora- men, which enters the spinal canal. These last two openings, with the demi-canal which unites them, replace the anterior notch; the posterior is altogether absent. Lastly, an inflected venous canal, whose position varies, and whose presence is not constant, crosses the laminw of the atlas, and opens, on one side, into the spinal canal, and on the other, beneath the trans- verse process. The atlas contains much compact tissue, and is generally developed : two for the body, which at an early period becomes a solid piece, and two for the annular part; the other two are complementary centres, each of which forms one of the two posterior undulated facets, and the lip of the corresponding transverse process. Second.—This is named the awis (or dentata). It is the longest of all the cervical vertebre ; those which succeed it gradually diminish in length and augment in thickness. The body of the axis has not any head anteriorly, THE VERTEBRAL COLUMN. 23 _ buta conical process termed the odontoid, which is flattened above and below, concave and rough from one side to the other on its superior face ; convex in the same direction, and perfectly smooth on its inferior face. The latter represents an articular half-hinge, around which glides the concave arti- ular surface on the superior face of the body of the atlas. The anterior articular processes are carried to the base and to each side of the odon- 1% toidian pivot, in the shape of two un- dulated facets, which are confounded with the gliding surface of the latter, whose destination has been already noted. The spinous process, very powerful and elongated antero-pos- teriorly, is divided behind into two qye axis, on DENTATA; LATERAL VIEW. roughened lips. ‘The transverse pro- 1, Superior spinous process; 2, Odontoid pro- cesses are slightly developed, and ter- cess; 3, Intervertebral foramen, or hole of minate posteriorly inasingle tubercle, conjugation; 4, Body; 5, Inferior spinous directed backwards. The anterior Pes; 6, 7, Inferior and superior articu- lating processes, Fig. 13. notches are very deep, and are most frequently converted into foramina. This vertebra, although voluminous, is light, in consequence of its containing much spongy substance. In the young animal, the odontoid process and the articular surfaces on each side, constitute two centres, distinct from each other and from the body of the vertebra. After the axis, the cervical vertebre diminish in length and increase in thickness ; while the obliquity of their articular processes becomes the more pronounced the more distant they are from that vertebra. Third, fourth, and fifth—Each of these has, at its transverse processes, two prolongations, one anterior, the other posterior. The inferior face of their bodies exhibits a median spine terminated posteriorly by a tubercle, which gradnally increases in volume from the third to the fifth vertebra. The third presents, between its anterior and posterior articular processes an almost complete gap; if its anterior extremity be placed on a horizontal plane, it will touch that plane by its articular and transverse processes and its head. In the fourth, the articular processes are united by a thin, sharp osseous plate, notched only in front. Laid on a horizontal plane, the head remains some distance from it. The fifth is known by the continuous, thick, _ and rugged lamina which unites the articular processes, and by the tubercle of the inferior spine on the body, which is in shape like the heart on a playing-card. Sixth.—This is distinguished by the slight prominence of the spinous process, but particularly by the almost total disappearance of the inferior spine, and the presence of a third prolongation, very strong and inclining downwards at its transverse process, a circumstance to which this vertebra owes its designation of tricuspid. Seventh.—This has received the name of prominens, because its spinous process, terminating in a point, is more distinct than in the preceding vertebre, the axis excepted. It exhibits, besides: deep imprints, which replace the inferior spine, a concave demi-facet on each side of the posterior cavity for the articulation of the head of the first rib; a particular disposition of its transverse processes, which are unituberculous ; the complete absence of the vertebral foramen; and, lastly, the depth and width of its notches. 24 THE BONES. The spinal foramen, which has already assumed a somewhat considerable diameter in the sixth cervical vertebra, is still larger in the seventh.! 2.—Dorsal Vertebre. — GeneraL Cuaracters.—In the dorsal vertebre the body is very short, and in front has a large slightly projecting head; behind, it has a shallow cavity. Laterally, these vertebre present, at the base of the transverse processes, four concave articular facets, the two anterior of which are situated near the head, while the posterior two are hollowed out of the border of the articular cavity of the body. Each of these facets is joined to Fig. 14. an analogous facet on the neighbouring ver- tebra to form a small excavation, into which is received the head of the cone rib. The spinous process is very high, is compressed on both sides, inclines backwards, and its summit is terminated by a tubercle, The transverse processes are unitubercular, and directed obliquely outwards and up- wards; on their external aspect they have a diarthrodial plane facet which corresponds — to the tuberosity of the rib. The articular processes are narrow, and constitute simple unrelieved facets cut on the base of the spinous process. The posterior notches are deep, and sometimes converted into foramina. Sreciric CxHaracrers.—None of the eighteen dorsal vertebre differ much from the type just described; and it is difficult Tyre oF A porsat vertesra; +0 establish special characters for each. THE FOURTH. It is, nevertheless, possible to assign to a 1, Body ; 2, 2, Articular facets for the dorsal vertebra, approximately, the rank it head of rib; 3, Articular facet for should occupy, in accepting the following tuberosity x = “an a copter facts as a guide:—1. The vertical diameter Heese a ee ec eene mone neagese, Of the vertebral bodies augments pro: spinous process 5 . J 7 Plctetion eetiedine ecco body; Sively from before to behind. Their lateral 8, 8, Transverse processes; 9, diameter, which determines that of the spinal Superior spinous process; 10, An- ¢anal, becomes, on the contrary, less from the terior articulation of body. first to the tenth vertebra; after which it assumes increasing proportions to the last one. The articular surfaces, which serve for the mutual contact of head and cavity, become larger and shallower in proportion as the vertebra are more posterior. The inferior spine on the body is very salient and tuberculous in the two first vertebrae, very acute in the third and fourth; it disappears in the sixth and ninth, to re-appear and become more marked from the tenth to the last. 2. The intervertebral cavities, intended for the reception of the heads of the ribs, diminish in depth and extent from the first to the last. 3. The longest spinous process belongs to the third, fourth, aud fifth vertebrw; those which follow gradually decrease to the eighteenth. Their width diminishes from the second to the eighth; it afterwards increases in a progressive manner in the succeeding vertebrae ; 1 M. Goubaux has sometimes met with asymmetrical cervical vertebre ; certain vertebra, tricuspid on one side, are only bicuspid or unicuspid on the opposite side. THE VERTEBRAL COLUMN. 25 from the second to the tenth vertebra, the summit of the spinous process is ‘large and tuberculous; in the last seven it is flattened laterally. Their 0 ity is less marked as they proceed backwards; in the sixteenth and seventeenth vertebre, the spinous process is nearly vertical; it inclines slightly forward in the eighteenth. Those of the tenth, eleventh, and _ twelfth vertebre are slightly curved like an 8. 4. The articular processes, from the first to the tenth vertebra, gradually contract and approach the median line; in the succeeding vertebrem they, on the contrary, increase, and become concave and wider apart from those of the opposite side. 5. The volume of the transverse processes and the size of their diarthrodial _ facets diminish from before to behind. In the three first vertebre this facet is concave; in the first nine the articular facet looks outwards and backwards, while the facet on the body looks forwards; in the last the two facets are directed forwards. These two facets are generally confounded in the seventeenth and eighteenth vertebre. The first dorsal vertebra much resembles the prominens; it is distinguished from it, however, by the presence of four diarthrodial facets on its extremities. It also differs from the other vertebra by the shortness of its spinous process, which terminates in a point; by the size and prominence of its articular processes ; and by the of its notches. The last vertebra never has facets on the contour of its posterior cavity." 3. Lumbar Vertebre. Generar Cuaracters.—A little longer and wider than the dorsal vertebra, which they resemble in the arrangement of their bodies, these vertebre are characterised: 1, By their short, thin, and wide spinous processes, which are slightly inclined forwards, and are provided at their summits with a scabrous tubercle; 2, By their largely developed transverse processes, flattened above and below, and directed horizontally outwards;? 3, By the salient anterior articular processes, hollowed out on each side, and provided externally with a tubercle for insertion; 4, By their equally prominent ’ ior articular processes, rounded in the form of a half-hinge. : Srzcrrio Cuaracters.—The characteristics which may serve to distinguish these vertebre from one another are derived from the body, and the spinous and tranverse processes. 1. From the first to the last there is a progressive diminution in the vertical diameter of the bodies, and an increase in their ; transverse diameter. The inferior spine on the body becomes shorter and wider from the first to the last vertebra; in the six vertebre it resembles an ; elongated triangle whose summit is directed forwards. 2. The spinous : decrease in width from before to behind, and their anterior ; border becomes more and more concave; their summits are thickened and tuberculous in the three first, and thin and sloping forward in the three last. 3. The transverse processes are longer in the middle vertebrae than in those placed before and behind. The processes in the first and . ? In well-formed horses, it is not uncommon to find nineteen dorsal vertebra, with an equal number of ribs; though in these in-tances there are most frequently only five lumbar vertebre. Husson and Goubaux have sometimes met with nineteen, and the normal number in the other regions. Sometimes there are only seventeen dorsal vertebra. 2 It has been correctly stated that these processes are the representatives of rudi- mentary ribs which have become united to the vertebra. Therefore it is that they are frequeutly designated costiform processes. 26 THE BONES. second vertebra incline slightly backward; in the third they are more up- right ; and in the succeeding ones are directed a little forward. In the last UPPER SURFACE OF LUMBAR VERTEBRA: 1, Summit of spinous process; 2, 2, Anterior articular processes; 3, 3, Posterior articu- lar processes; 4, 4, Transverse processes. Fig. 16. LUMBAR VERTEBRA; FRONT VIEW. 1, Body; 2, Its articular face; 3, Superior spinous process; 4, Spinal foramen; 5, Anterior articular processes; 6, 6, Transverse, or costiform pro- cesses; 7, Posterior articular process. two they are remarkable for their thickness ; in the fifth an oval-shaped. articular facet is observed on their posterior border; in the sixth, two are present—one in front, co ing to the preceding, and one behi slightly concave, meeting a similar facet on the sacrum. The fourth and fifth vertebre very often correspond, at their transverse processes, by means of analogous facets.’ In the Ass, and sometimes in the Mule, only five lumbar vertebre are found. According to M. Sanson, this is the natural number in the Arab Horse.” 4, Sacrum. The sacrum results, as already stated, from the consolidation of five vertebre. This single bone articulates, in front, with the last lumbar vertebra; behind, with the first coccygeal bone, and on the sides with the ossa innominata. It is triangular, flattened above and below, and from before to behind describes a slight curve up- wards. It offers for study a superior and an inferior face, two borders, a base, a summit, and a central canal, the exten- sion of the spinal canal. Faces.—The superior face presents, on its middle, the spi- nous processes of the sacral vertebra, which together con- stitute what is called the sacral or supersacral spine. These processes are united at their base only, and remain isolated for the remainder of their ex- tent; they all incline backwards ' We possess the skeleton of a horse which has seven lumbar vertebra, with the normal complement in the other regions. The seventh is no doubt the first sacral, as it has all its characters. The fifth sacral vertebra is evidently derived from the coceygeal region. 2 (This statement is scarcel correct. M. Sanson has established the fact that there is in reality no Arab horse; and asserts that the specific type with five lumbar vertebra, is very probbl of African origin, and that these vertebra, independently of their number, ividu offer in which has six.) al characteristics different from those observed in the vertebra of the type : THE VERTEBRAL COLUMN. 27 and terminate, with the exception of the first, by a tuberous summit, which is often bifid; their length diminishes from the second to the fifth bone. On each side of the sacral spine exists a groove, at the bottom . Fig. 17. supersacral foramina. These oe canal, communicate with NS four analogous, but wider aper- tures, pierced at the inferior face of the bone, and for this reason named the subsacral fo- ramina. The inferior face is smooth, and shows traces of the primitive separation of the ver- tebral bodies ; the subsacral fi a 1, Articular surface of body ; 2, 3, Articular surfaces ramina, which represent, with corresponding to those on the transverse processes the corresponding supersacral of last lumbar vertebra; 4, Spinal foramen; 5, openings, the intervertebral fo- Auricular facet; 6, Anterior articular processes ; ramina of the other regions of 7; Inferior or subsacral foramina; 8, Superior the spine, aro ol ed on this a processes; 9, Summit or coccygeal ex- LATERAL VIEW OF SACRUM. Borders.—The two borders, thick and concave, form, posteriorly, a rugged lip; in front, they present an irregular surface inclining obliquely from above to below, from within outwards, and from before to behind. This surface, which is intended for the articulation of the sacrum with the ossa innominata, is divided into two parts: one, the inferior, named in man the auricular facet, is slightly undulated and diarthrodial; the other, the superior, serves for ligamentous insertions. Base.—This offers: 1, On the median line, the anterior orifice of the sacral canal, and the anterior articular surface of the body of the first sacral vertebra, which is oval and slightly convex; 2, On the borders, the articular processes and anterior notches of this vertebra, as well as the elliptical and somewhat convex facets which bring it into contact with the transverse processes of the last lumbar vertebra. Summit.—The summit, thrown back, presents: 1, The posterior orifice of the sacral canal; 2, The posterior articular surface of the body of the last sacral vertebra; 3, The vestiges of the articular processes and posterior notches of that vertebra. Sacral canal.—This is the portion of the spinal canal which is channeled out of the sacrum; it is triangular, and diminishes in width from before to behind. 5. Coceygeal Vertebre. The coccygeal region, or coccyx, comprises from fifteen to eighteen de- generate vertebra, which gradually diminish from the first to the last. In the first three or four, nearly all the characteristics of true vertebrw are found; they show a spinal foramen, a body, a spinous process, and transverse processes, looking backwards; the articular processes only are altogether absent. In the succeeding vertebrm, these characters become effaced ; the vertebral laminw do not join completely, and the spinal canal is only a simple groove, which, gradually decreasing in depth, at last 28 THE BONES. entirely disappears. The insertion eminences also be¢ome less salient, and the coccygeal vertebre are soon reduced to small bony cylinders, narrow in the middle and wider at both extremities, with a convex arti surface at each end (except the last, which has only one articular ~— These small cylinders, the last traces of the vertebral bodies, are developed from three centres of ossification; they are very spongy and light. The first coceygeal vertebra is frequently consolidated with the sacrum in aged animals. THE SPINE IN GENERAL, The vertebral column has now to be considered in its entirety, and examined successively in its superior face, its inferior face, its lateral and its spinal canal, Afterwards its direction and mobility will be noticed. Superior face.—This presents, on its median line, the series of spinous processes. But little salient in the cervical region, these eminences are much developed in the dorsal and lumbar, where they constitute a long crest, the dorso-lumbar spine, as well as in the sacrum, where they form the sacral spine. They soon disappear in the coccygeal vertebra. Outwards, and on each side of these processes, is seen a succession of tubercles of insertion, represented in the cervical and lumbar vertebra by articular processes, and in the dorsal vertebre by the superior or rugose portion of the transverse processes. These tubercles are disposed in line, and separated from the spinous processes by a channel designated the vertebral groove, which is more or less deep and wide. It is on these, and on the spinous processes, that the extensor muscular fasciculi of the spine receive the greater portion of their fixed or moveable insertions. Inferior surface.—Wide at the neck, this face becomes narrow in the dorsal region, to be again widened at the lumbo-sacral region, and once more contracted at the coccyx. Crests more or less developed, which divide the vertebral bodies into two lateral portions, right and left, are remarked. Lateral surfaces.—These offer for study the thirty-six intervertebral foramina, through which the spinal nerves pass. They exhibit besides, on the neck, the transverse processes; in the back, the external facets of these processes, and the intervertebral facets, all destined to sustain the heads of the ribs; on the loins, the transverse or costiform processes. It may be remarked that the ribs and the transverse processes of the neck and loins furnish points of insertion to the powerful muscles which produce the lateral movements of the spine. In the sacrum, the lateral faces are formed for the articulation of the spine with the ossa innominata. Spinal canal.—This canal communicates, in front, with the cranial cavity. Very wide in the atlas, for the reception of the odontoid process and to permit the rotatory movements of the head without injury to the spinal cord, this canal suddenly diminishes in the axis. It again dilates at the termination of the cervical region and the commencement of the dorsal; there the spinal cord presents a greater volume, and the movements of the spine are very extensive. Towards the middle of the back, the spinal canal offers its smallest diameter; it widens from this part to the lumbo-sacral articula- tion; after which it contracts rapidly, and disappears altogethor near the fourth or fifth coccygeal vertebra. The lumbo-sacral dilatation coincides with the enlargement of the cord in this region, and with the enormous quantity of nerves lying beside it. OO Ee a a THE VERTEBRAL COLUMN. 29 * Direction of the vertebral column.—The spine does not extend in a _ straight line from the head to the posterior extremity of the body. If it is followed from the caudal termination, which is free and looks downwards, to the anterior extremity, it will be seen that it rises upwards and forwards, forming a convex inflexion corresponding to the roof of the pelvis. In the lumbar and the posterior half of the dorsal region it is nearly horizontal and rectilinear; from thence it descends to the cervical region, when it rises and forms two curves, the one posterior, bending upwards, the anterior, turned down. This disposition of the cervical spine gives it the shape of a console. Mobility of the vertebral column.—In the cervical region, the almost total absence of spinous processes, the great development of the articular and the very short curve described by the surfaces of contact of the vertebral bodies, allows the spine very extensive and very diverse movements. In the dorsal region, however, these movements are very limited, the spinous processes and the costal arches preventing the play of the vertebre on each other. In the lumbar region, the spine can be flexed or extended more than in the dorsal; but its lateral movements are uite as restricted, owing to the presence of the transverse processes and the reciprocal joining or dovetailing of the articular processes. Lateral motion is even rendered impossible in the posterior half of.this region, from the manner in which the transverse processes are adapted to each other. It may be remarked, however, that this disposition singularly favours the integral transmission of the propulsive efforts thrown upon the trunk by the posterior extremities. The sacral vertebre, having to afford the ossa innominata a solid fixed point, could not preserve their independence and mobility, and are conse- quently consolidated into a single piece which fulfils all its requirements in this respect. In the coccyx the rachidean stalk again recovers its mobility, and to a degree more marked than elsewhere ; the coccygeal bones, articulated with each other by means of convex surfaces, and deprived of long processes at their extremities, are placed in the best possible conditions for variety and extent of movement. DIFFERENTIAL CHARACTERS IN THE VERTEBRAL COLUMN OF OTHER THAN SOLIPED ANIMALS, The Numper of Preces niger’ Sprvez slightly varies in the Domesticated Animals, as will be seen in the following Tasix, ; VERTEBR 2. ANIMALS. : Cervical. | Dorsul. | Lumbar, | Sacral. | Coceygeal. Ox 7 13 6 | 5 16 to 20 Sheep 7 13 6 or 7 + 16 to 24 Goat y | 13 6 + 11 to 12 Pig . 7 14 6 or 7 4 21 to 23 Dog 7 13 7 3 | 16to21 Cat 7 13 7 3 21 A. Verresr” or tue Ox, Sneer, anp Goat.—l. Cervical Vertebre.—The cervical vertebre of the Oz differ from those of solipeds by their shortness and the greater deve- nt of their insertion eminences. In the Sheep and Goat they are relatively longer than in the Ox, The transverse processes of the ches are less inclined than in the Horse, 30 THE BONES. and have no vertebral foramina; the posterior facets for articulation with the axis are nearly flat and join cach other, The axis has a semicylindrical, not a conical, odontoid process, which is so concave on its upper surface that it looks like a groove. Its spinous process is not so thick as in the Horse, and is not bifid posteriorly. In the jive succeeding vertebrx, a rugged continuous lamina unites the anterior artieular processes to the posterior, ‘The spinous process inclines forward and is flattened trans- versely at its summit, which is sometimes bifid; it augments progressively in height from the third to the fifth vertebra. ; In the sixth, the transverse processes have only two prolongations—a superior and inferior; the latter, large and flattened on both sides, is bent abruptly downwards. ‘The spinous process has already atiained the height of 1} to 2 inches in this vertebra, and is flattened mogecs The seventh well deserves the name of prominens: its spinous process being no less than from 4 to 4} inches. 2. Dorsal vertebre.—In the Ox these bones are longer and thicker than in the Horse. Their spinous processes are larger and incline more backward ; their transverse processes — are very voluminous, and are provided with a convex facet from above to below; while their posterior notches are nearly always converted into foramina. Considered individually, they are more slender in the middle than at the extremities. Their spinous processes diminish in width, especially at their summits, from the first to the eleventh vertebra, and widen again in the two last; they pro ively increase in slope to the tenth, after which they become more and more upright; the first four are the longest, and are nearly the same in height; the others gradually decrease. +. In the first four or five vertebra, the articular facet of the transverse processes, while retaining its vertical convexity, is concave in an antero-posterior direction. This facet is always ubsent in the last vertebra, and sometimes even in the preceding one. The two bones terminating the dorsal region show, in addition, the articular processes disposed like those of the lumbar vertebra. The dorsal vertebrae of the Sheep and Goat are relatively less ars 3 than those of the Ox ; their spinous processes are not so wide, and their posterior notches are never con- verted into foramina. 3. Lumbar vertebre.—The lumbar vertebree of the Ox are longer and thicker than in the Horse. The transverse processes are also generally more developed, are concave on the anterior border, convex on the posterior, and incline slightly downward, with the exception of the two first, which remain nearly horizontal. They increase in length from the first to the fourth vertebra; in the latter and tlie fifth, they are nearly of the same dimensions; in the last they suddenly become shorter. Their width gradually decreases from before to behind. In the fifth and sixth vertebra, these processes have no articular facets between them and the sacrum, these being only met with in solipeds, The artic- ular processes are prominent, and further removed from the median line as they belong to posterior vertebree. In the Goat the transverse processes are more inclined downwards. In the Sheep, on the contrary, the processes rise up towards their extremities. 4. Sacrum.—The sacrum of the Ox is more voluminous und curved than that of the Horse. The spinous processes are entirely consolidated, and are surmounted by a thick rugged lip; they are lengthened at their and on each side by a ridge that represents the rudiments of the articular processes. The lateral borders are sharp and bent down- wards. The surfaces that serve to unite the sacrum to the ossa innominata have a some- what vertical direction. There are no lateral facets on the base of the bone for the union of the sacrum with the transverse processes of the last lumbar vertebra. In the and Goat, the sacrum is shorter; sometimes the consolidation of the spinous processes is late, or never occurs. 5. Coccygeal vertebrx.—In proportion, the coccygeal vertebre of ruminants are stronger and more tuberous than those of the Horse. The anterior articular processes exist in a rudimentary condition. B. Verresre or THE Pia.—1. Cervical vertebrw.—Of all the domesticated animals, this has the rte widest, the most tuberous, and consequently the strongest cervi- eal vertebra. The y of these bones is deprived of its crest on the inferior face; its head, but little detached, is scarcely round, and looks as if driven back on itself; con- sequently, its posterior cavity is not deep. The vertebral laminew are very narrow, and scarcely extend from one part of the vertebra to the other in the superior portion; so that the spinal canal appears at this point to be incomplete. F In the atlas, the transverse processes are yet less inclined than in ruminants; the vertebral foramen is not constant, and when it exists, opens on one side, under the io _ i r THE VERTEBRAL COLUMN. Bl transverse process, and on the other, on its posterior margin, after pursuing a certain track in the substance of the bone. ’ ¥ : ? Seched by tte ? _— aoe axis is constricted at sendy Fe tag ig is distin- its an spinous process inclining slightly y its transverse Seing But slightly prominent and perforated by an enormous vertebral ; In the four succeeding vertebrw, the spinous process terminates in a blunt point, and ' inclines forward ; slightly salient in the first, it gradually rises in the others. The trans- verse processes form two prea one, the superior, is tuberculous, and is age to = anterior articular 2. Dorsal etal —The Pig has — dorsal yertebree, which, in their general disposition, are not unlike those of the Ox. As with that animal, the intervertebral fora- mina are double, each vertebral lamina being seagate: rated laterally by an opening situated in front of the posterior noteh. In addition, ertebre of the Pig present this pecu- liarity, that their transverse processes are generally traversed at the base by a single or - multiple foramen which communicates with the preceding. ith regard to the special characters proper to some of the vertebra, these are, as with the other animals, very few, and may be described as follows: 1. The transverse pro- cesses of the four vertebra preceding the last project but slightly; 2. In the fourteenth this process resembles those of the lumbar vertebre ; 3. The articular facet of the trans- verse veel saved in the four last vertebre is confounded with the anterior lateral facet to the head of the rib; 4. The articular processes of the last five vertebrae eps ama 9 like those of the lumbar vertebre ; and the prominence furmed by the fabeiels on the outside of the anterior articular process replaces, to a certain. degree, the oc aga of these vertebree. 3. vertebrz.—These bones in the Pig greatly resemble those of ruminant animals. It commonly happens that seven are met with; but in this case the supple- mentary vertebra is generally a sacral one. It is not denied, however, that seven Sell vertebree may exist in the Pig, along with the normal number of sacral vertebra. —_- PR Sacrum.—This is formed by four vertebre, which are a long time in becoming fused together ; and it is often difficult to discover where the sacrum ends and the coccyx begins. The spinous processes are entirely absent. The vertebral laminw are not consolidated ; so that the spinal canal is half cut through in its upper portion, as in the ae ir region; this canal is also much compressed above and below. Coecygeal vertebre.—These vertebre in the Pig are more particularly distin- gue bythe ae cee of of articular processes, by means of which the foremost bones eac C. VesTEBRZ OF THE ‘Dos anp Catr.—1. Cervical Vertebre.—In these animals, the cervical vertebrw are long and thick, and much resemble those of soli Nevertheless, besides their smaller volume, they are distinguished: 1, By the isposition of their articular surfaces; the anterior, or head, is nearly flat, and is even slightly excavated in its centre ; the posterior, or cavity, is but little hollowed to receive the head of the next vertebra ; 2, By the width of the vertebral lamine, which exactly cover one another; 3, By the ‘height of their spinous processes, which increases as the vertebre 4 | , . : extend back; 4, By the great extent of the anterior and posterior articular processes, which are united by means of a continuous and very salient bony plate, that considerably augments the transversal diameter of each vertebra. In the atlas, the articular surface for the odontoid pivot is confounded in front with the cavities which correspond to the occipital condyles, The two facets which are annexed ° peeriety to this articular surface, instead of being plane or gently undulated, as in the : ' This can always be made out, however, by consulting the disposition of the articular processes. Thus, in the sacral vertebrx these eminences—if we except the ‘ anterior ones of the first and the a of the last—never exist except in a rudi- : mentary state; while in the other five coccygeal vertebre they re-appear with all their characters. B2 THE BONES. other domesticated animals, are transformed into real paws cavities.’ The transverse processes are carried directly outwards and a little backward; the lip which borders each is slizhtly raised; of the two foramina which replace the anterior notch, one only exists, and this penetrates to the interior of the spinal canal; the other is merely a sit fe notch te” In the azis, the odontoid process is cylindrical, narrow at its base, and bent a little upwards; the lateral facets of this eminence sane true condyles.* The spinous rocess is very thin and undivided, and is curved forward above the lamin of the atlas. — he anterior notches are never converted into foramina, i, The third cervical vertebra is the largest; and the succeeding ones wa diminish in thickness to the last, contrary to what occurs in the other The — sagt does not show the spinous process so developed as in ruminants and pachyderms ==— (see Fig. 1). = 2. Dorsal vertebre.—In the Dog the dorsal vertebra are formed on the same model as those of the Horse; but their spinous processes are in general narrower and thicker. The tenth always has its spinous process vertical, triangular, and terminated in a point, The last three have no posterior facets for the articulation of the heads of the and exhibit, in the conformation of their articular processes, the same a as the lumbar vertebrae, In the Cat, the transverse processes of the three last dorsal vertebrae : ave cy sharp, and turned backwards; they never possess facets for the tuberosity of the ri ; 3. Lumbar vertebre—In the Dog and Cat, the lumbar vertebre are remarkable for their strength, due to their length, thickness, and the development of the eminences of — insertion. The spinous process is low, and becomes acute in the last vertebra. The transverse processes incline very much forward and downward ; they become longer from the first to the second-last bune; in the latter they become contracted, and in the seventh vertebra they are still more diminished, and terminate in an obtuse point. The tubercle of the anterior articular process is extremely prominent, and the posterior notches are surmounted by a small, very acute prolongation, directed backwards, which becomes more developed towards the anterior vertebre. T is small prolongation exactly represents the transyer-e process of the dorsal vertebre. 4, Sacrum.—The three vertebre which form the sacrum of carnivora are early con- solidated. The supersacral spine constitutes a thin sharp ridge; while the surfaces for articulation with the ossa innominata are turned quite outwards and are nearly vertical. : 5. Coceygeal vertebre.—The vertebree of the coecyx are very strong and tuberous. The first five or six are as perfect as the true vertebrae, and comport themselves in every respect like them. The last are small V-shaped bones, which M. Goubaux has by the name of hypstloid bones. : : . . r mart vee ee » -¥ COMPARISON OF THE VERTEBRAL COLUMN OF MAN WITH THAT OF THE DOMESTICATED ANIMALS, ; The vertebral column of Man is composed of twenty-nine bones: twenty-four vertebrae, tiomivrs and four pieces constituting the coccyx. The twenty-four vertebre are thus istributed : ; Cervical vertebre . . .-.-.. 7 Dorsal es pitiand.. eeveree Lumbar ” . . 5 In all these vertebra, the bodies are slightly excavated at the two extremities, while in the domesticated animals, the superior or anterior is convex, and the inferior or posterior concave, 1. Cervical vertebre.—Tlese are wide and short. The spinous processes are mode- rately developed and bifid «t their summits; the transverse processes are also divided into two branches—a posterior and an anterior. 2. Dorsal vertebre.—In these vertebre, the bodies increase in thickness from the first to the last. In the first as well as in the last dorsal vertebrae, the spinous process is almost immediately directed backwards; in the middle portion of this region these processes are very obliquely directed downwards and backwards. 1 (A glenoid cavity is a shallow, oval, articular depression.) 2 (A condyle is an articular eminence representing an ovoid segment, Condyles always correspond to the glenoid cavities in the articulations.) a Ee Le ‘ "enormous development of frontal, sph temporal, is double. - THE HEAD. 33 \ 8. Lumbar vertebra —The lumbar vertebre are the strongest bones in the spine, and their bodies are nearly as thick as those of the larger domesticated animals. e lumbar vertebre in Man is related to his position as a biped. This In the fifth, the lower face of the body is cut very obliquely backwards and upwards, and the transverse processes are more voluminous than those of the other lumbar vertebre. 4. Sacrum.—The sacrum is formed by the union _ of five pieces. It is very concave from above to below and before to behind. In becoming united to the lumbar region, it forms a salient angle in front, to which has been given the name of promon- tory or sacro-vertebral angle. The sacral spine is continuous or interrupted, according to the subject ; it is alway bifid inferiorly. 5. vertebre.—These are little bones or flattened tubercles, four in number, rarely five, and usually consolidated. ‘I'he coccyx is conical in shape. Its base shows two processes directed up- wards, which are called the cornua of the coceyx. Its summit is often deviated to the right or left. Articte I1.—Tue Heap. The head is a large bony pyramid, elon- gated from above to below, and quadran- gular, suspended to the anterior extremity of the spine ; it is in a direction varying with the attitudes of the animal, but which we will suppose, for convenience of description, to be nearly vertical. It is formed of a great number of particular bones, which are only distinct from one another in very young animals ; for well before the adult period is reached the majority of the bones are united and cannot be separated. The head is divided into two parts: the cranium and the face. BONES OF THE CRANIUM. The cranium, or upper part of the head, is composed of seven flat bones, five of which are single: the occipital, parietal, id, and ethmoid ; one only, the These bones cireum- scribe a central cavity, the cranial, which communicates behind with the spinal canal, and lodges the principal portion of the nervous centres—the encephalon. 1. Occipital Bone. The occipital bone occupies the superior extremity of the head, which it supports from the anterior extremity of the spine. This bone is very irregular in its form, and is bent at a right angle in front and behind. Tt has an external and an internal face, and a circumference which brings it into contact HORSE’S HEAD; FRONT VIEW. 1, Occipital protuberance ; 2, Origin of the mastoid crest ; 3, Parietal bone ; 4, Saggital suture; 5, Junction of the parietal and temporal bones; 6, Zygomatie arch; 7, Frontal bone; 8, Frontal suture; 9, Tem- poral fossa ;.10, Supraorbital fora- men; 11, 12, Lachrymal bone; 13, Malar bone; 14, Nasal border of frontal bone; 15, Nasal bone; 16, Suture of nasal bones ; 17, Superior maxillary bone; 18, Infraorbital foramen; 19, Anterior, or pre- maxillary bone; 20, Foramen in- cisivum ; 21, Incisor teeth—young mouth. with the adjoining cranial bones; the latter is subdivided into two anterior D 34 THE BONES, lateral borders, two posterior lateral borders, an anterior and posterior salient angle, and two lateral re-entering angles. Faces.—The external face is divided into three portions by the double flexure of the bone: one looks forward, another upward, and the third backward. It exhibits :—-1. On the median line, and from before to behind : a, an antero-posterior ridge which constitutes the origin of the parietal ridges, to be mentioned hereafter; b, a transverse, voluminous, and very prominent eminence, marked posteriorly by deep imprints, with a medium projection named the cervical tuberosity; this is the external occipital pro- tuberance which, in the Horse, corresponds at the same time to the curved lines of the occipital bone of Man. This protuberance forms the culminating point of the head, and divides the anterior and superior parts of the external face of the bone; c, the occipital foramen ( foramen magnum), % large orifice that passes through the bone at the posterior flexure, and esta- blishes a communication between the cranial cavity and spinal canal; d, the external surface of the basilar process, a narrow and thick prolongation ‘formed by the bone as it passes to meet the sphenoid : this surface is convex laterally, 2. On the sides: a, A sharp crest which prolongs, laterally, the superior curved lines, and descends on the middle of the lateral anterior border to be continued with the superior root of the zygomatic process and the mastoid crest of the temporal bone; b, Linear imprints, parallel to the latter, and prolonged on the base of the styloid process: they are destined for the insertion of the small oblique muscle of the head, and represent the inferior curved lines of the occipital bone of Man; c, Within these imprints is a slightly- roughened cavity for the insertion of the posterior recti muscles; d, The two - condyles, articular eminences with a double convexity, one superior, the other inferior : these eminences are situated on each side of the occipital foramen (foramen magnum), and correspond to the anterior cavities of the atlas; e, More outwards are the two styloid processes, or jugular eminences, long projections flattened on each side, terminated in blunt points, directed back- wards, and separated from the condyles by a deep space, the stylo-condyloid notch; f, Under the condyles is the condyloid fossa, a smooth depression, pierced at the bottom by the condyloid foramem which penetrates the cranium, The internal face of the occipital bone is concave, and shows: behind, the foramen magnum ; above, an uneven surface, which forms the roof of the cerebral cavity ; below, the superior face of the basilar process, slightly hollowed into a groove; on the sides, the internal orifice of the condyloid foramen, Circumference.—The anterior lateral borders are thick, and are united by suture with the parietal bone, and with the tuberous portion of the temporal bone by the harmonia! suture. The posterior lateral borders are sharp, and constitute the sides of the basilar process; each concurs in the formation of the occipito-spheno-temporal hiatus, also termed the lacerated foramen, a vast irregular opening, extending from above downwards, penetrating the cranium, and divided by a ligament, in the fresh state, into two portions, one inferior, the anterior lacerated foramen, the other superior,’ the posterior lacerated foramen. The anterior angle, which is dentated, is dovetailed into the parietal bone. The posterior angle is very thick, and forms the summit of the basilar process; it is united by suture with the body of the sphenoid. The lateral re-entering angles, or jugular notches, correspond to the ' (The harmonia suture (peiv, to adapt) is the simple apposition of contiguous borders, which are roughened to facilitate retention.) * (The anterior and posterior lacerated foramen of Man.) THE HEAD. 35 point where the bone is bent posteriorly; they separate the anterior lateral the corresponding posterior lateral border, and are occupied by the tuberous portion of the temporal bone. Struciure.—The occipital bone contains much spongy substance. _ Development.—it is developed from four centres of ossification: one, the anterior, is single, and forms the occipital protuberance; another, the posterior, also single, forms the basilar process ; the other two are pairs, and com each a condyle, with the styloid proccss and the corresponding yloid foramen. 2. The Parietal Bone. The parietal is a wide and thin bone, very much arched to form the roof of the cranial cavity. It is bounded above by the occipital bone, below by the frontal, and laterally by the-two temporal bones. — It offers for study an external and internal face, and a circumference divided into four regions or Faces.—The external face is convex. It exhibits two curved 7*1ges whose concavity is directed outwards; these two crests, which ar¢ .ermed the parietal ridges, approach each other and unite superiorly, tc se continued with the antero-posterior ridge of the occipital bone; bel: they diverge and proceed, one on each side, to join the supraorbital process. They divide the surface of the bone into three portions: two lateral, which are rough and traversed by vascular channels, forming part of the temporal fosse ; the third, or middle, is plane, smooth, and of a triangular form, and covered by the skin. The internal face is concave, covered by digital impressions, and grooved by small vascular canals; it offers, on the median line, and altogether above, the parietal eminence.‘ This trifacial and very salient pro- jection presents at its base, on each side, an excavation elongated trans- versely, into which opens the parieto-temporal canal, and which is destined to lodge a venous sinus. It is continued, in front, by a median crest, which is often replaced by a slight groove, the ‘saggital furrow, bordered by linear imprints. Two other ridges, resulting from the abutment of the lateral border of the bone against the anterior face of the petrous bone, rise from the sides of this eminence and descend to the sphenoid bone; they separate the cerebral from the cerebellar cavity. Borders.—The superior border is notched, thick, and slightly dentated ; it articulates with the occipital bone. The inferior border, slightly concave, and deeply dentated, offers an external bevel in its middle portion, and an internal bevel on its sides; it corresponds with the frontal bone, The lateral borders are very thin, and are cut at the expense of the external plate into a wide, sloping edge, which shows a groove destined to form the parieto-temporal canal. A very prominent angle separates each into two portions, an inferior, that articulates by suture with the squamous portion of the temporal bone ; and a superior, curved inwards towards the centre of the cranial cavity; the latter portion of the lateral border is in contact with the anterior face of the petrous portion of the temporal bone, with which it concurs to form the lateral crest that descends to the parietal eminence, Structure.—This bone contains much compact tissue, the spongy sub- stance existing only in its middle. Development.—It is developed from two large centres of ossification, to * The internal occipital eminence of Man. n2 36 THE BONES. which is added a single centre to form the parietal eminence.' In early life the parietal ridges are absent. 8. Frontal Bone. The frontal is a flat quadrilateral bone, whose sides are bent in the middle at an acute angle, and are carried back, and a little inwards, to meet the wings of the sphenoid bone. It assists in forming the cranial roof and part of the face. It is bordered: above, by the parietal bone; below, by the nasal and lachrymal bones; and on each side, by the temporal bones. It offers for study an external and an internal face, and four borders. Faces.—The external face is divided, by the double flexure of the bone, into three regions: a middle and two lateral. The first, nearly plane, is lozenge-shaped, is covered by the skin, and constitutes the base of the fore- head. It gives rise on each side, at the point where it is inflected, to a lo process, flattened above and below, which curves backward, forming the orbital arch, 'The superior or external face of this process is convex and slightly roughened ; the internal face is smooth and concave, and forms part of the orbital fossa. Its posterior border, thick and concave, is continued, in- wardly, with the corresponding parietal ridge, and outwardly with the superior border of the zygomatic process. It limits, in front, the temporal fossa. The anterior border, also concave, but thin, concurs in the forma- tion of the orbital margin; the summit, thickened and denticulated, rests upon, and is united to, the zygomatic process of the temporal bone; the base is wide, and is traversed by an opening termed the supraorbital, or super- ciliary foramen. ‘The two lateral regions of the external face of the frontal bone are slightly excavated, and assist, for the greater portion of their — extent, to form the orbits. They often show, near the base of the orbital — arch, a small depression corresponding to the flexure described by the great oblique muscle of the eye in passing through its pulley. The internal face of the frontal bone is concave, and divided into two unequal parts by a transverse ridge, corresponding to the anterior border of the cribriform plate of the ethmoid bone. The superior, the most extensive, is covered with digital impressions, and belongs to the cranial cavity. It exhibits: 1, On the median line, a slight furrow, or a crest which is con- tinuous, above, with the median ridge of the parietal bone, and below, with the crista-galli process ; 2, On the sides, and in the re-entering angle formed by the flexure of the bone, there is a narrow slit, or mortice, which receives the wing of the sphenoid bone. The inferior part is united, on the median line, to the perpendicular plate of the ethmoid. It assists in forming the bottom of the nasal cavities, and presents laterally two large openings which lead to the frontal sinuses—vast anfractuous spaces excavated between the two plates of the bone. Borders.—The superior border is denticulated, and cut obliquely, in its middle portion, at the expense of the internal plate, and on the lateral at the expense of the external table; it is in contact with the parietal and 1 This centre is described as the interparietal bone by those anatomists who consider the two lateral centres as two distinct parietals. (Leyh is one of the veterinary anatomists who describe-this nucleus as a separate bone, designating it the falciform or interparietal bone. He also describes the parietal as a pair or double bone; whereas the majority of French anatomists include the interparietal bone as the median protuberance of the arietal, which they look upon as a single or impair bone, Percivall names it a pair bone, but follows the example of the French hippotomists with regard to the interparietal.) >. THE HEAD. 37 Squamous portion of the temporal bone. The inferior, prolonged to a point in the middle, is in apposition with the nasal bones through the medium of a wide external bevel; laterally, it is very thin, faintly serrated, and articulates with the lachrymal bone. The lateral borders, thin and irregular, present two notches: one, the superior, is wide and deep, and occupied by the wing of the sphenoid bone; the other, inferior, is very narrow, and uniting with a similar notch in the sphenoid bone, forms the orbital foramen, which opens into the cranium, very near, but external to, the ethmoid fossa. Each of these borders, also, is adapted, for a limited extent, to the corresponding palate bone. Structure.—The two compact plates of the frontal bone are separated by spongy texture towards the middle and in the upper part; they separate below to form the frontal sinuses. Laterally, they are very thin and consolidated with each other. _ Development.—The frontal bone is developed from two lateral centres of ossification, which only coalesce at a late period. In youth ‘he cranial portion of the bone forms, in front of the head, a large rounded ». vtuberance standing beyond the facial portion. This prominence disap ars when the frontal sinuses begin to be developed. These cavities do .ot exist at an early period of foetal life ; but commence to form about the fourth month of conception, by a process of resorption, which removes the spongy substance i between the two compact tables of bone, and may even cause the destruction of the internal table. The sinuses enlarge with age, and remain during life separated from one another by a vertical septum. 4, Ethmoid Bone. The ethmoid bone, deeply situated in the limit between the cranium and the face, is inclosed between the frontal, the sphenoid, the vomer, the palate, and the supermaxillary bones. It is composed of three portions: a perpendicular plate, and two lateral masses. Tue Perrenpicutsr Lamina or tHE Eramom Bone.—Situated in the median plane, and flattened on both sides, this bone presents two faces, a left and right, and four borders. Faces.—The faces, covered by the pituitary membrane, present, pos- teriorly, small sinuous crests ; elsewhere they are smooth. A very narrow interval, constituting the bottom of the nasal cavities, separates them from the lateral masses. ’ Borders.—The supericr border looks towards the centre of the cranial cavity, and constitutes what is called the ethmoidal ridge, or crista-galli process. It is free, concave, and sharp, prolonged in front and above by the median crest of the frontal bone, and confounded behind with the middle portion of the inferior sphenoid. The inferior border is continuous with the cartilaginous plate which separates the nasal cavities. When this plate becomes ossified, which is not unfrequent, it is impossible to discover the point where it begins or the ethmoid bone terminates. The middle septum of the nose has been considered, and justly, as a prolongation of the perpen- dicular plate (or lamina) of this bone. The anterior border is consolidated with the vertical septum which separates the frontal sinuses. The posterior border is joined, above, to the median plate which divides the sphenoidal sinuses into two compartments. Below, it is fixed in the groove of the vomer, and soon becomes confounded with that bone, which is itself conso- lidated with the inferior sphenoid. Larerat Masses or tHe Erumom Bonr.—-These are two large pyriform 88 THE BONES. tuberosities placed on each side of the perpendicular lamina, and offering for study a middle portion, a base, and a summit, Each of these is formed by an assemblage of numerous, extremely thin, osseous plates, curved into small and very fragile convolutions. nasal cavities, and by one of their borde These, elongated from above to below, become longer as they are more anterior; they are attached by their superior extremities to the transverse plate which separates the cranium from the ANTERIOR BONES OF THE HEAD OF A FCTUS (HORSE) AT BIRTH; VIEWED FROM BEHIND. DISARTICULATED, AND rs to a thin leaf of bone which envelops the lateral masses out- wardly. They have received the — of the ethmoidal volutes (or cells). iddle portion.—This should be studied externally and inter- nally. The external surface of each ethmoidal mass is divided into two sections: an internal, making part of the nasal cavities; the other, external, coneurs in form- ing the walls of the frontal and maxillary sinuses. The first, the least extensive, is almost plane ; parallel to the perpendicular la- mina, it is isolated from it by the narrow space which forms the bottom of the nasal cavities; it presents several openings which separate the most superficial cells, and join the internal canals to be hereafter noticed. The second, A, Occipital bone—1, Condyle; 2, Con- dyloid foramen; 3, Styloid process; 4, Summit of basilar process.—B, Parie- tal bone.—8, Parietal protuberance; 9, Channel which concurs to form the parieto-temporal canal.—c, Frontal bone.—10, Transverse crests separating the cranial from the facial portion of the bone; 11, Frontal sinuses; 12, Notch on the lateral border occupied by the wing of the sphenoid bone; 13, Notch for the formation of the orbital foramen; 14, Summit of the orbital process; 15, Supraorbital foramen.— D, Perpendicular lamina of the ethmoid bone.——£, E, Lateral masses of the eth- moid bone.—16, The great ethmoid cell. —F, Squamous portion of the temporal bone.—17, Supercondyloid process ; 18, Channel for the formation of the parieto-temporal canal.—G, Tuberous portion of the temporal bone,—5, Mas- toid process; 6, Internal auditory hiatus; 7, Opening for the eustachian tube into the tympanum.—n, Lach- rymal bone.—1, Nasal bone.—J, Su- perior turbinated bone. a ee THE HEAD, 39 yery extensive and convex, looks outwards in front and behind, and is covered by an osseous plate traced with shallow furrows, which correspond internally with the small crests to which the cells are attached. This lamella is inferiorly, a little beneath the inferior extremity of these latter, and turns outwards to articulate with the palate and superior maxillary bones; superiorly, it coalesces with the sphenoid and the orbital portion of the frontal bone. Internally, the lateral masses are hollowed from above to below by | extremely diverging canals, which open inferiorly into the nasal cavities, and separate the cells from one another. ‘he latter are so incurvated that the internal cells communicate with each other. There are some, however, which are completely closed ; the anterior, or great cell, is frequently so." Base.—T he base of each lateral mass looks upwards, and is formed by the transverse septum between the cranium and the nasal cavities. This is perforated by openings which give passage to the ethny _ 1 nerves; it is named the cribriform plate of the ethmoid bone. It / concave on the superior surface, which constitutes the ethmoidal fossa, nod convex on the opposite face, where attachment is given to the superior extremities of the cells. It is consolidated internally with the perpendicular plate; the other points of its circumference are attached to the sphenoid bone, and to the transverse ridge on the internal face of the frontal bone. it.—The summit of each lateral mass is formed by the inferior extremity of the ethmoidal cells, which is directed downwards towards the nasal cavities. One, more voluminous than the others, is carried much lower, and terminates by a rounded protuberance. It corresponds to the middle cornu (concha media) of Man. Structure of the ethmoid bone.—Very little spongy tissue enters into the composition of this bone, and this is only found near the anterior border of the perpendicular plate. Development.—The ethmoid bone is late in attaining its development, and the adjoining bones are nearly completely ossified when it is yet entirely cartilaginous. The bony transformation commences in it at the inferior extremity of the cells, and advances progressively from below upwards, The perpendicular plate is only ossified in part when the cel!s have passed through the first half of the process; at the same time it coalesces with the inferior sphenoid. The cribriform plate is the last to become ossified; this transformation haying scarcely been achieved when the animal is six or eight months old. 5. Sphenoid Bone. The sphenoid bone is situated behind the cranium, between the occipital, ethmoidal, palate, vomer, pterygoid, frontal, and temporal bones. It is flattened from before to behind, curved from one side to the other, thick in its middle part, named the body, and thin on the sides, which, in their inferior half, are prolonged in the form of ale or wings. It has two surfaces and four borders. " Surfaces.—The external surface is convex, and presents: 1, On the median line, the external surface of the body, rounded from one side to the other, is continued with that of the basilar process, and has marked mus- cular imprints superiorly ; 2, On the sides and from within outwards: a, the vidian (or pterygoid) fissure, directed from above downwards, and con- tinued by the vidian canal, a very small foramen which opens into the ' It is not rare to find it opening into the frontal sinus. 40 THE BONES. > orbital hiatus; b, the subsphenoidal, or pterygoid process, a long eminence, flattened on both sides, inclining downwards, articulating with —— and pterygoid bones, and traversed at its base by the vidian 36,8) little behind and above this eminence, the superior orifice of the sub- sphenoidal foramen, a large canal which bifurcates inferiorly ; d, more in front, the orbital hiatus, a kind of vestibule into which open in common the principal branch of the subsphenoidal canal, the three supersphenoidal canals, the vidian and optic canals, and the orbital opening: this hiatus is surmounted by a thin and sharp bony plate, above which opens the smallest branch of the subsphenoidal foramen; e, altogether without the hiatus is remarked a smooth surface belonging to the wing of the sphenoid, and which concurs to form the orbital cavity. The internal face is concave from side to side. It shows: 1, On the median line, and from before to behind, a small projection united to the crista-galli ; the optic fossa, elongated transversely in the form of a shuttle, and presenting at the bottom, and on each side, the superior orifice of the optic foramen, a cylindrical canal directed obliquely downwards, forwards, and outwards, to reach the orbital hiatus; the supersphenoidal or pituitary fossa, also named the sella turcica, a slight depression, limited behind by a — searcely noticeable transverse projection separating it from the superior channel of the basilar process; 2, On the sides, and in front, the internal surface of the wings, depressed by very superficial digital impressions ; more behind and outwards, a fossa, elongated from before to behind, which lodges the mastoid lobule of the brain; between this fossa and the sella turcica, two vertical fissures : an internal, named the cavernous sinus, and an external, wider and deeper, for the passage of a large nervous branch. These two fissures open below, near the junction of the three super- _ sphenoidal canals. Two of these, which are very wide, are placed one before — the other, and separated only by a slight partition. The superior of these constitutes the great sphenoidal fissure ; the other, the lower, is the foramen rotundum, and opens into the orbital hiatus. The third, very small, is situated outside the great anterior canal, opens above the optic foramen, within the — bony mass surmounting ‘the hiatus, and sometimes on the free margin of this lamina. Borders.—The superior is a little concave, and shows, in its middle, the superior extremity of the body, mammillated and articulated with the summit of the basilar process; on each side, two notches which circumscribe below the occipito-spheno-temporal hiatus (foramina lacera basis cranii). The internal notch is the narrowest, and from its affording a passage for the internal carotid artery, is called the carotid notch; it is continued on the external face of the bone by a smooth excavation to which Rigot has given the name of carotid fossa. The external is also prolonged on the exterior surface cf the sphenoid by a short and wide fissure; it lodges the inferior maxillary nerve. Outside this is another very narrow notch, intended for the passage of the middle meningeal artery. The fibro-cartilaginous sub- stance that partly fills the occipito-spheno-temporal hiatus, transforms these notches into foramina, the first of which is named the carotid canal, the second, the foramen ovale, and the third, the foramen spinosum. The inferior border, also concave, is likewise divided into three portions, a middle and two lateral. The first is thick, and formed by the inferior extremity of the body; it is excavated by two large cavities belonging to the sphenoidal sinus. ‘These cavities are separated from one another by a vertical osseous plate, — often perforated, which, at an early period, is fused with the perpendicular THE HEAD. 41 lamina of the ethmoid bone. The very thin lateral portions form part of the circumference of the wings; they are notched near their union with the middle piece to assist in the formation of the orbital foramen. The two lateral borders are thin and convex in their an- terior half, as is also the contour of the wings, which are mortised in the frontal bone. For the remainder of their extent they are thick, denticulated, and bevelled at the expense of the external plate, to articulate with the squamous portion of the temporal bone. Structure.—This bone is compact on its sides, and spongy in its middle part ; inferiorly, it is excavated by the sphe- p noidal sinuses. .—It is developed from two principal nuclei of ossification ; a superior forms the subsphenoidal pro- cess and the canal of the same name, the vidian fissure, pituitary fossa, fissures of the internal face, and the most pos- terior of the great supersphenoidal canals ; the other, the inferior, forms that portion of the body hollowed by the sinuses, the lateral alw,! and the optic fossa and canals. In meeting each other, these centres form the vidian canal and the two anterivr supersphenoidal canals. They are not consolidated with each other until a very late period ; for which reason they are sometimes de- scribed as two distinct bones. M. pogrerrorn poxes or THE HEAD OF A Tabourin has even proposed to attach yarus (Horse) AT BIRTH; DISARTICU- the description of the inferior sphenoid LATED AND VIEWED IN FRONT. to that of the ethmoid, because it is 4, Sphenoid bone,—1, Maxillary notch; 2, united with this bone a long time before C#rotid notch ; 3, Groove for the passage “5 see ° ° of the maxillary nerve; 4, Cavernous it is joined to the superior portion. sinus; 5, Optic fossa; 6, Great wing; 6. Temporal Bone. 1, Notch for the formation of the orbital The temporal bones inclose the gas he bie. ree sag : < . b, Zygoma.—£, Superior maxilla.—_8, In- cranial cavity Jaterally and articulate ferior orifice of the maxillo-dental canal, with the occipital, parietal, frontal, _», premaxillary bone, sphenoidal, and the zygomatic bones; also with the inferior maxilla and the hyoid bone. Each is divided into two pieces, which are never consolidated in the horse; one forms the squamous portion of the temporal bone ; the other, the tuberous portion. They will be described abaeaiehe: Squamous Portion.—This is flattened on both sides, oval, and slightly incurvated like a shell, a shape to which it owes its name. It offers for study an external and an internal face, and a circumference. ' These wings are not analogous to those portions of the sphenoid bone in Man bear- ing the same name. They are the processes of Ingrassias enormously developed. 42 THE BONES. Faces.—The external face is convex, and marked by some muscular imprints, vascular fissures, and openings which penetrate the parieto- temporal canal. It forms part of the temporal fossa, and gives origin near its middle to the zygomatic process, a long eminence which at first runs outwards, and soon curves forwards and downwards to terminate in a thin summit. The base of this eminence forms, in front, a concave surface belonging to the temporal fossa ; behind, it offers the articular surface which corresponds with the maxillary bone. The latter is composed of: 1, A condyle transversely elongated, convex above and below, and slightly concave from side to side; 2, A glenoid cavity, limited below by the condyle, above by a mammiform eminence, the supercondyloid,' against which rests the i condyle when this bone is drawn backwards; it is immediately above this eminence that the inferior orifice of the parieto-temporal canal opens. The external face of the zygomatic process is smooth and convex; the internal, concave, is also smooth, and bordered eutwards by the temporal fossa. Its anterior border is sharp and convex; the posterior, very short, is thick and roughened, Its summit is flattened from before to behind, and marked by notches on its two faces; it somewhat resembles a wedge, fixed as it is between the orbital process of the frontal bone and the zygoma; it comes in contact with the maxillary bone, and by a small portion of its anterior face, which is deprived ot notches, it concurs in cireumscribing the orbital cavity, In the domesticated animals, as in Man, the zygomatic process appears to arise from the surface of the bone by two roots: one, the inferior or transverse, is represented by the condyle; the other, the superior, forms a sharp crest which is continuous with the anterior border of the process, and above, joins the lateral crest of the occipital protuberance. The internal or cerebral face of the squamous portion is divided into two parts by an almost vertical channel which terminates above the super- condyloid eminence, and which, meeting a similar furrow on the parietal bone, forms the parieto-temporal canal. The superior portion is but of small extent, and of a triangular form; it articulates by a simple harmonia suture with the external face of the petrous portion. The inferior part, the widest, presents in its middle some cerebral impressions. For the re- mainder of its extent or circumference, it is cut into a wide, dentated, and lamellar bevel, which brings it in contact with the surrounding bones. Circumference.—This may be divided into two borders: one, anterior, is convex and united with the parietal and frontal bones; the other, posterior, articulates with the sphenoid in its inferior moiety, and is provided, above the level of the supra-condyloid eminence, with a deep notch which receives the external auditory canal, Superiorly, the two borders unite at the summit in a thin point which rests on the occipital bone. Structure.—The squamous portion of the temporal bone is formed of two very thin compact plates which have but little spongy tissue between them ; the latter, however, is very abundant in the body of the zygomatic TOCESS. 7 Development.—It is developed from a single nucleus of ossification. Tuserovus Porrion.—This is one of the most interesting parts of the skeleton for study, in consequence of its containing two systems of cavities which inclose the essential organs of hearing. One of these systems is named the cavity of the tympanum or middle ear ; the other forms the internal ‘ear. These cavities will be studied when we come to speak of the auditory ' In Man this is represented by the inferior or vertical ramus of the upper root of the zygomatic process, THE HEAD, ; 43 at ip a In the meantime, only the exterior surface and the structure development of this portion of the temporal bone will be noticed. It is wedged between the antero-lateral border of the occipital bone, the lateral border of the parietal, and the superior part of the internal face of the temporal shell. It represents a quadrangular pyramid whose base is turned downwards and a little backwards. It will be studied successively in its four faces, a summit, and base. Faces.—The anterior face is united by harmonia suture to the parietal bone. The posterior face articulates in the same manner with the occipital bone. The external face lies against the squamous portion of the bone. The internal face, slightly concave and marked by very superficial digital impressions, forms a part of the lateral wall of the cerebellar cavity. Tt presents the canal or internal auditory hiatus (meatus auditorius internus), a small fossa, the bottom of which is pierced by several foramina for the transmission of nerves; the largest of these is the internal orifice of the aqueductus Fallopii, a flexuous canal which passes through the bone and opens at the external surface of its base; the other foramina penetrate the ' cavities of the internal ear. ! These faces are separated from each other by so many borders or plane angles, two of which more particularly merit attention; one of these isolates the external from the posterior face, and the other separates the anterior from the internal face. The first is thick and rugged, and constitutes the mastoid crest ; it is continuous above with the lateral ridge of the occipital bone, after being united to the superior root of the zygomatic process, and terminates, near the base of the bone, by a tuberosity for muscular insertion, to which has been given the name of mastoid process. This border is traversed by a slit, the mastoid fissure,’ which passes under the squamous portion and enters the parieto-temporal canal. The second is thin, and, with the superior part of the lateral border of the parietal bone, forms the crest which establishes the line of demarcation between the cerebral and pone ae, Tal cavities of the cranium; it gives attachment to the tentorium cerebelli. O yongpaitiaiaan is slightly denticulated, and articulates with the occipital e. Base.—This is very irregular, and offers : outwardly, the external auditory canal which penetrates the middle ear, and the external orifice of which has been named in veterinary anatomy the external auditory hiatus ; inwardly, a sharp crest which cireumscribes the external contour of the lacerated foramen ; above, and under the mastoid process, the stylo-mastoid or pre-mastoid foramen, the external orifice of the aqueduct of Fallopius; below, the subuliform (or styloid) process for the attachment of the stylo-staphyleus (tensor palati) muscle and the Eustachian tube : this is a long, thin, and pointed process presenting, at its base and within, a canal which enters the cavity of the tympanum, and which is incompletely partitioned by a small bony plate into two parallel portions ; in the centre, the hyoid prolongation or vaginal process,? a little cylindrical eminence surrounded by a bony sheath, and the mastoid or process, a slightly salient, smooth, and round eminence owed internally by numerous cells, which form part of the middle ear. The several small and very remarkable canals which pass through the tuberous portion of the temporal bone, will be noticed when the neryous and arterial branches they lodge are described. ? This is the analogue of the mastoid canal in Man. * This process is prolonged by a cartilage that unites it to the styloid bone, a 4 THE BONES. Development.—The tuberous portion of the temporal bone is developed from two principal centres of ossification which are consolidated at birth, and which are often described as two distinct portions: the one as the petrous or stony portion, the other as the mastoid portion. The faces, borders, summit and inner side of the base of the bone are formed by the petrous part, which contains the cavities of the internal ear and furnishes the inner wall of the middle ear. The mastoid portion constitutes almost entirely the base of the temporal pyramid; to it belongs the external anditory canal, the mastoid process, the sheath of the hyoid prolongation, and the styloid process; it forms the external wall and circumference of the case of the tympanum. For the tuberous portion of the temporal bone there are also two small complementary nuclei: one for the vaginal process, whose base is united to the petrous portion, and another forming the ring of the tympanum. Structure—The petrous portion is the hardest mass of bone in the skeleton, and scarcely contains any spongy tissue, except at the centre of the mastoid process ; in the mastoid portion it may be said not to exist. In the other domesticated animals, the tuberous portion of the temporal bone is always consolidated with the squamous, and the summit of the — zygomatic process only articulates with the malar bone. BONES OF THE FACE, The face is much more extensive than the cranium in the majority of the domesticated animals, and is composed of two jaws, a bony apparatus that serves as a support to the passive organs of mastication—the teeth. The superior or anterior jaw, traversed in its entire length by the nasal cavities, is formed by nineteen wide bones, only one of which, the vomer, is a single bone; the pairs are: the superior and intermawillaries (or premawillaries), the . pterygoid, zygomatic, lachrymal, nasal, and superior and inferior turbinated bones. Of these only four, the maxillaries, are intended for the implantation of the teeth; the others form the union between the cranium and the superior maxilla, or concur in the formation of the nasal cavities. The lower jaw has for its base a single bone, the inferior maxilla or masillary bone. 1. Great Supermaxilla, or Superior Mawillary Bone. This bone, the most extensive in the upper jaw, is situated on the side of the face, and is bordered above by the frontal, palate, zygomatic, and lachrymal bones; below, by the premaxillary bones ; in front, by the nasal bone; behind and within, by that of the opposite side. It is elongated vertically, is irregularly triangular, and exhibits two faces, two borders, and two extremities. Faces.—The external face, which is more convex in the young than the old animal, presents: 1, On the level of the fourth and fifth molar teeth, a vertically elongated ridge which is continued above with the inferior border of the zygomatic bone; this is the supermawillary spine ; 2, The inferior orifice of the supermazillo-dental canal, or infra-orbital foramen. The internal face concurs in forming the external parietes of the nasal cavities. We observe, above and in front, a deep, wide, and diverticu- lated excavation, forming part of the maxillary sinus; above and behind, a surface roughened by fine lamelle and dentations to correspond with the palate bone, and traversed from above to “below by a fissure which forms, in uniting with a similar fissure in the latter hone, the palatine canal. For the remainder of its extent it is unequally smvoth, covered by the membrane _ a —_— =. - Se —_— THE HEAD. 45 of the nose, and divided into two surfaces by a slightly vertical and sinuous crest that affords attachment to the maxillary turbinated bone: the anterior surface, which responds to the middle meatus of the nasal fossa, shows the lower orifice of the osseous lachrymal canal continued by a fissure to the lower extremity of the bone ; the posterior surface belongs to the inferior meatus. This face presents, near its inferior border, a large vertical apophysis, the palatine process, which offers an anterior slightly concave face, forming the floor of the nasal fosse; a posterior face, furrowed by small fissures, perforated by fine openings, and traversed along its length by a somewhat wide groove, the palatine fissure, which commences above at the lower orifice _ of the palatine canal. The internal border of this process articulates with the analogue of the palatine process of the opposite side. Borders.—The anterior, thin and convex, is divided into two parts: an inferior, which is mortised to receive the external border of the nasal bone and the external process of the premaxillary ; and a superior, cut in a wide bevel at the expense of the external plate, to respond to the lachrymal and zygomatic bones. The external border is very thick and hollowed into six quadrilateral cavities, named alveoli, in which are implanted the molar teeth. Above the last alveolus it forms a rugged eminence designated the alveolar tuberosity ; below the first it becomes thin and sharp, and constitutes part of the interdental space which separates the molar from the incisor teeth. Extremities.—The superior is the thickest, and represents a smooth rounded protuberance, into the interior of which the maxillary sinus is . Above and within this eminence, is a wide and deep excavation, in the formation of which the palate bones participate. This is the maxillary hiatus, situated directly opposite the orbital hiatus. At the bottom of this cavity is seen the nasal foramen, as well as the upper orifice of the supermaxillo-dental and the palatine canals. The nasal foramen belo to the palate bone and enters the nasal cavity. The super- seesle dental or infra-orbital canal traverses the maxillary sinus in passing above the roots of the molar teeth, and terminates by two branches: one, short and wide, which opens on the external surface of the bone, on a level with the third molar; the other, very narrow, continues the course of the canal in the thickness of the bone, and is prolonged by several small very fine branches into the premaxillary bone. The palatine canal, channeled between the supermaxillary and the palate bone, extends from the maxillary hiatus to the palatine fissure. The inferior extremity presents a cavity which forms the alveolus of the tusk by uniting with a similar space in the premaxillary bone. Structure and development.—This bone is developed from a single nucleus, and is the more spongy, particularly towards the alveolar border and the superior extremity, as the animal is young. 2. Premavillary, Intermaxillary, Anterior Maxillary or Incisive Bone. This bone occupies the inferior extremity of the head, and is composed of a thick prismatic portion, lengthened superiorly by two long processes. Thick portion or base.—This presents a solid mass with three faces: an external or labial, smooth and convex; an internal, denticulated for union with the opposite bone, and traversed from before to behind by an inflexed fissure, which forms, with an analogous one in the other premaxillary, the incisive canal or foramen ; the third or posterior, also called the buceal, is slighty concave, and shows the continuation of the palatine fissure, which 46 THE BONES, opens into the incisive foramen. These three faces are separated by as many borders: two internal, limiting before and behind the corresponding face ; and an external, separating the labial from the buecal face. The latter only merits notice; it is very thick, and is divided into two parts: an inferior, which describes a curved line with the concavity upwards, and is hollowed by three alveoli to receive the incisor teeth; another, the superior, is straight, vertical, and somewhat sharp, and forms a part of the dental interspace. It is limited above, near the base of the external process, by a cavity for the formation of the alveolus of the tusk. Processes.—These are distinguished as ex- Fig. 21. ternal and internal, The first, the longest and strongest, is flattened on both sides; its ex- ternal face is smooth and continued with that of the thiek portion of the bone; its internal face is covered by the mucous membrane of the nose; the anterior border is smooth and rounded; the posterior, denticulated to re- spond to the supermaxillary bone, is in con- tact with the external border of the base ; its summit is thin, and is insinuated between the latter and the nasal bone. The internal pro- cess, the smallest, is flattened from before to behind, and forms a very thin tongue of bone, separated from the other portions by a nar- row and very deep notch named the incisive opening or cleft. Its inferior face constitutes a small portion of the floor of the nasal fosse ; the posterior, continuous with the same face of the principal mass of the bone, forms part of the palatine roof; its external border cir- cumscribes, inwardly, the incisive opening ; the internal is united by dentated suture with the opposite bone. Structure and development.—It is a spongy bone, developed from a single nucleus. 3. Palate Bones. The palate bones are situated between the supermaxillaries, at the margin of the guttural opening of the nasal cavities, and are articu- POSTERIOR ASPECT OF HORSE’S lated with the sphenoid, ethmoid, vomer, SKULL, frontal, and pterygoid bones, Elongated from 1, Occipital protuberance; 2, above to below, flattened laterally, and curved Foramen magnum; 3, 3, Oc- cipital condyles; 4, 4, Styloid processes; 5, 5, Petrous bone; 6, Basilar process; 7, Pterygoid fissure of the sphenoid bone; 8, Foramen lacerum; 9, 9, Supra-condyloid, or anterior mastoid process; 10, 10, Articular eminence, or temporal condyle; 11, Body of sphenoid bone; 12, Pterygoid process; 13, Ethmoid bone; 14, Temporal bone and sphe- noidal suture; 15, Lachrymal bone; 16, Vomer; 17, Malar bone; 18, Maxillary tube- rosity; 19, Posterior, or guttural opening of the nose; 20, Palate bone; 21, Palatine styloid process; 22, Palato-maxillary foramen; 23, Palatine process of superior maxil- lary bone with suture; 24, Ditto of premaxillary bone; 25, Premaxillary bone; 26, Upper incisor teeth; 27, Point of junction of the premaxillary with the superior maxil- lary bone; 28, Upper molar teeth—young mouth. ‘= =. THE HEAD. 47 towards each other at their inferior extremity, which is flattened from before to behind, these bones, though irregular in shape, offer for study two faces, two borders, and two extremities. Faces.—The external face of the palate bone is divided into three frac- tions, a superior, or orbital, an inferior, or palatine, and a middle, or articular. The first is smooth and slightly excavated, and participates in the forma- tion of the maxillary hiatus; it shows a small fissure, the staphyloid, which reaches the palatine fraction in passing between the posterior border of the bone and the alveolar tuberosity. The second is not extensive, and looks backwards in consequence of the antero-posterior flattening which the bone re ‘at its inferior extremity; it forms part of the roof of the palate. third presents a lamellar and denticulated surface which corresponds to a similar face on the supermaxillary bone, and is channeled from above to below by the internal fissure of the palatine canal, The internal face, smooth and concave, forms part of the. external wall and the floor of the nasal fossa. Borders.—The anterior is indented, near its superior third, by a. deep notch, which is often converted into a foramen, the nasal. Below this notch the bone is thin and denticulated for union with the supermaxillary bone ; aboye, its two plates separate widely from one another, giving rise to a very spacious cavity which forms part of the sphenoid sinus. The posterior border presents, above, a rugged crest called the palatine, flattened from side to side, bent outwards, and bordered at its base and inwards by a very narrow synarthrodial surface which responds to the pterygoid bone. It is smooth and concave in its inferior half, and forms, with that of the opposite side, a parabolic arch which circumscribes, below and at the side, the double gutt orifice of the nasal cavities. Ezxtremities.—The superior, flattened on both sides, is bevelled on the external side to articulate with the subsphenoidal process. The inferior, flattened from before to behind, is curved inwards and united by simple suture with that of the opposite bone. Structure and development,—This is a very compact bone, developed from a single centre of ossification, : : | ; | 4, Pterygoid Bone," A small and very narrow bone, elongated from above to below, flattened on both sides, and situated on the inner aspect of the subsphenoidal process, . but external to the vomer. | Its external face is in contact with the palate and sphenoid*bones ; ; the infernal is smooth and covered by the pharyngeal mucous membrane. Its superior extremity is tapering, and concurs in forming the vidian canal ; the inferior is thickened into a small pointed process (the hamular process), whose apex, directed backwards, offers outwardly a groove which serves as a | pulley to the tendon of the tensor palati, This bone is composed entirely ; of compact tissue, and is developed from a single centre of ossification, 5. Zygomatic Bone. This bone, also designated the malar and jugal bone, is elongated from above to below, flattened on both sides, and irregularly triangular in shape; sit is situated on the side of the face, and articulates with the supermaxillary, This bone is the representative of the internal wing of the pterygoid process in Man. —_— 48 THE BONES. lachrymal, and temporal bones. It is described as having two faées,two borders, a base, and a summit. ar ! Faces.—The external face comprises two portions separated from each other by a semicircular ledge that extends from the summit to the middle of the anterior border of the bone, and concurs to form the outer margin of the orbit. The anterior portion, smooth and concave, belongs to the orbital cavity. |The posterior, more extensive, is also smooth and slightly convex. The internal face is excavated in its central part, which corresponds to the maxillary sinus. On its margin it shows dentations and lamellw for articu- - lation with the supermaxillary bone. Borders.—The anterior, thin and denticulated, is joined to the lachrymal bone. The posterior, or masseterin border, is thicker, and constitutes a roughened crest, the zygomatic ridge, which is continued above with the posterior border of the process of the same name, and below with the maxillary spine.? ; Base and summit.—The base, very thin, is united to the su bone. The summif, flattened from before to behind and bevelled on its anterior face, joins the zygomatic process, and forms with it the jugal bridge or zygomatic arch. «sae Structure and development.—This bone is rather spongy in its upper part, — and is developed from a single nucleus of ossification. , . : 6. Lachrymal Bone. 1p . A small, thin, and very light bone, bent on itself at a right angle, it is situ- ated beneath the orbit, which it aids in forming, and is wedged between the frontal, nasal, supermaxillary, and zygomatic bones. It is studied on its external and internal faces and circumference. Faces.—The external is divided into two regions, superior and inferior, by a curved crest which forms part of the orbital margin, and is provided | with notches, which are variable in their form and number. The superior region, named the orbital, because of its situation in the orbit, is slightly concave and smooth. It presents, near the orbital margin, the orifice of the lachrymal duct, which traverses the maxillary sinus and opens on the internal face of the supermaxillary bone, where it is continued by a fissure ; behind this is the lachrymal fossa. The inferior or facial region is slightly bulging, and provided sometimes with a tubercle of insertion, the lachrymal tubercle. The internal face is employed, for the whole of its extent, in the formation of the walls of the maxillary and frontal sinuses; it exhibits a cylifdrical prominence produced by the bony tube of the lachrymal duct. Circumference.—This is very irregular and denticulated to respond to the neighbouring bones. Structure and development.—This bone is entirely compact, and is developed from a single nucleus of ossification. 7. Nasal Bones. Situated on the anterior aspect of the head, these bones articulate with each other in the median line, and are fixed between the frontal, lach and supermaxillary bones; they are triangular in shape, elongated from above to below, flattened from before to behind, and offer for study two faces, two borders, a base, and a summit. Faces.—The external or anterior face, larger above than below, is convex‘ : ‘ ‘ 1 The designation of zygomatic crest is often given to these three parts collectively, a forms THE HEAD. - side to side and almost smooth. The 4 a: or nasal face exhibits a ver- crest passing along the external border of the bone, which gives attachment to the _ nated portion of the ethmoid; at its supe- rior extremity this crest bifurcates, and between its two branches shows a concave surface which of the frontal sinus. For the -remain of its extent the internal face is _ smooth, and covered by the mucous membrane of the nasal fossa; it is also excavated into a channel to form the superior meatus of this cavity. Borders.—The external border is very thin ~ its upper two-thirds, and articulates with the lachrymal bone, the anterior border of the supermaxillary, and the upper extremity of the premaxillary bones. In its lower third it becomes isolated from the latter bone, in forming with the anterior border of its large process a very acute re-entering angle whose looks downwards. The internal border Oo Sanammag to correspond with the opposite e. Base and Summit.—The base occupies the superior extremity of the bone; it describes a curved line with the convexity above, and in uniting on the median line with that of the opposite bone, forms a notch similar to that of the heart figured on playing cards; it is bevelled at the expense of the internal plate to articulate with the frontal bone. The summit of the two nasal bones, which is pointed, constitutes the nasal prolongation: the name given to a single triangular process which comprises all that portion of the nasal bones separated from the premaxillaries by the re- ing angle before mentioned. Structure and deve .-—Almost entirely compact in structure, it is developed from a aeamare 8. Turbinaied Bones. The turbinated bones, two on each side, represent two, irregular bony columns, wider above than below, compressed laterally, hol- lowed internally, and lying vertically side by side on the external wall of the nasal fossa, which they divide into three meatuses or pas- They are distinguished into anterior and posterior turbinated bones. The anterior or superior, also named the 49 ANTERO-POSTERIOR AND VERTICAL SECTION OF THE HORSE’S HEAD. 1, Condyloid foramen; 2, Parietal protuberance; 3, Internal audi- tory hiatus; 4, Cerebral cavity ; 5, Cerebellar cavity; 6, Supe- rior border of the perpendicular plate of the ethmoid bone (crista- galli process); 7, Ethmoidal volutes—nasal face ; 8, Vestiges of the right frontal sinus; 9, Ditto of the sphenoidal sinus ; 10, Pterygoid process; 11, Eth- moidal turbinated bone; 12, Maxillary turbinated bone; 13, Crest of the supermaxillary bone to which the latter is fixed ; 14, Vomer.—a, Orifice of com- munication between the nasal cavity and the sinus, E THE BONES. LONGITUDINAL AND TRANSVERSE SEC™ TION OF THE HORSE’S HEAD, SHOW~ ING THE FLOOR OF THE CRANIAL — AND NASAL CAVITIES, WITH THE MAXILLARY SINUSES. Condyloid foramen; 2, Section of the parieto-temporal canal; 3, Occipito- spheno-temporal hiatus; 4, Carotid notch; 4’, Maxillary notch.—a, Supermaxillary fissure; 6, Cavernous fissure; 5, Origin of the supersphe- noidal canals.—c, Sella turcica; 6, Optic fossa; 7, Portion of the erista-galli process; 8, Cribriform plate of the ethmoid bone; 9, Per- pendicular plate of the same bone; 10, 10, Its lateral masses; 11, Inte- rior of the great ethmoidal cell; 12, ~~ —— ethmoidal, is formed by a very thin plate of compact tissue, fragile and like fixed by its anterior border to the internal crest of the nasal bone, and rolled on itself, from before to behind, in the same manner as the cells of the ethmoid bone, Above, it is confounded with the last- named bone, of which it is only, baie 90 speaking, the most anterior volute. At its by inferior extremity, it is prolonged by a fibro-cartilaginous framework to the ex- ternal orifice of the nose. Its internal cavity is partitioned by a transverse plate into two portions: the superior compartment forms part of the frontal sinus; the inferior is subdivided by other small lamelle into a variable number of cells which communicate with the nasal cavity. This bone, developed from a single nucleus, is ossified at the same time, and in the same manner, as the ethmoidal cells. Before birth, it is already intimately consolidated with the nasal bone. The posterior, inferior, or mazillary turbinated bone resembles the first, except in some particulars. Thus, its bony or proper portion is not so long or volu- minous, while its cartilaginous part is, on — the contrary, more developed. It is at- tached, by its posterior border, to the ver- tical and sinuous crest of the s maxillary bone, and is rolled from behind to before, or in an inverse direction to the other. It has no connection with the ethmoid, and its superior cavity forms part of the inferior maxillary sinus. It is late in becoming ossified, and is scarcely united in a definife manner to the max- illary bone until the horse is about a year old. The meatuses are distinguished into anterior or superior, middle, and posterior or inferior. The first passes along the front of the ethmoidal turbinated bone; the second separates the two turbinated bones, and présents, near its superior extremity, the opening communicating between the sinuses and the nasal cavi- 12, Bottom of the maxillary sinuses communicating with the sphenoidal sinuses; 13, Supe- rior maxillary sinus; 14, Inferior maxillary sinus; 14’, Superior compartment of the max- illary turbinated bone, forming part of the latter sinus; 15, Section of the supermaxillo- dental canal; 16, Channel of the vomer; 17, Internal process, or point of the premax- illary bone. THE HEAD. 51 _ ties. The third is situated behind the maxillary turbinated bone, and is confounded with the floor of the nasal fossa. _ The turbinated bones are essentially destined to furnish the membrane of the nose with a vast surface of development. This membrane, indeed, covers their entire superficies, and even penetrates the anfractuous cells of their lower compartment. 9. Vomer. This, a single bone, elongated from above to below, flattened on both sides, and extending on the median line from the body of the sphenoid to the premaxillary bone, offers for study two lateral faces, two borders, and The faces are smooth, plane, and covered by the nasal membrane. The anterior is channeled for the whole of its length by a deep groove _ which receives the posterior border of the cartilaginous septum of the nose. The posterior border is sharp and smooth in its upper half, which separates the two guttural openings of the nasal cavities: it is thick and slightly denticnlated for the remainder of its extent, and rests on the median suture resulting from the union of the two supermaxillary bones. The superior extremity is provided, in its middle, with a notch which divides it into two lateral prolongations shaped like a cat’s ears: it articulates with the inferior sphenoid, ethmoid, palate, and pterygoid bones. The inferior extremity rests on the prolongations of the incisive bones. This bone is entirely compact, and is developed from one centre of ossification. 10. Inferior Maxillary Bone. The maxillary bone is not consolidated with any of the preceding bones, and is only united to two of them, the temporals, by diarthrodial articula- tion. It is a considerable bone, situated behind the upper jaw, and composed of two symmetrical branches, which are flattened on both sides, wider above than below, curved forwards in their upper third, joined at their lower extremities, and separated superiorly so as to leave a wide gap between them, like the letter V in shape, called the intramazillary space. Each offers for study two faces, two borders, and two extremities. Faces.—The external face of the maxillary branches is smooth and rounded in its inferior two-thirds, and transformed superiorly into a surface, in which is implanted the fibres of the masseter muscle. The internal face presents, in the corresponding point, an excavated surface on which is remarked the superior orifice of the mawillo-dental canal, a long channel which descends between the two plates of the branch, passing under the roots of the molar teeth, and insensibly disappearing in the body of the bone after being widely opened externally by the mental (or anterior maxillary) Joramen. In its inferior two-thirds, the internal face is smooth, nearly and shows nothing very remarkable. Near the alveolar border there a slightly-projecting line—the myloid ridge ; and quite below, or rather at the very summit of the re-entering angle formed by the separation of the branches, there is a slight rugged excavation confounded with that of the opposite brauch, and named the genial surface. Borders.—The anterior, also named the alveolar border, exhibits for study a straight or inferior, and a curved or superior portion. The first is hollowed by six alveoli to receive the inferior molar teeth. * The two turbinated bones, in being applied against the excavation on the inner face of the supermaxillary, almost entirely close it, only leaving between them a vertical rlit which constitutes the opening mentioned above. P Ra 52 THE BONES. The second, thinner, concave, and rugged, serves for muscular insertion. The posterior border is also divided into straight and curved portions. ‘The latter is convex, thick, rugged, and margined on each side by an uneven lip; the first is regularly rectilinear, so that all its points rest at the same time on a horizontal plane; it is thick and rounded in the young animal, but becomes sharp with age; an oblique and transverse fissure—the mawillary —separates it from the curved part, ‘The union of these two portions forms the angle of the jaw. Extremities—The superior extremity has two eminences: a condyle, and a long non-articular process named the coronoid process. The condyle is elongated transversely, and convex in its two diameters ; it responds, through the medium of a fibro-cartilaginous disc, to the articular surface of the zygo- matic process. The coronoid process is situated in front of the condyle, from which it is separated by a division called the sigmoid or corono-condyloid notch ; it is flattened on both sides, and curved backwards and slightly inwards. INFERIOR MAXILLA, 1, Mental foramen; 1’, Superior orifice of the maxillo-dental canal; 2, Surface ot implantation for the masseter muscle; 3, Myloid ridge; 4, Coronoid process; 5, Condyle. From the union of the branches of the maxillary bone at their inferior extremity results a single piece, flattened before and behind, and widened like a spatula, which has been designated the body of the bone. This merits a special description. Its form allows us to divide it into an anterior or Luccal face,’a posterior or labial face, and a cireumference. The anterior face is smooth and concave, is lined by the buccal mucous membrane, and supports the free extremity of the tongue. The posterior face is convex, more extensive than the preceding, and continuous with the external face of the branches ; it presents: 1, On the median line, a slight crest or small groove, traces of its bei originally separated into two pieces; 2, On the sides and above, the foramen, the inferior orifice of the maxillo-dental canal. On a level with this foramen, the bone very markedly contracts to form the neck. The circumference describes a parabolic curve, the concavity being u and joins, by its extremities, the anterior border of each branch. It is excavated in its middle part by the six alveoli for the lodgment of the —————— THE HEAD. 53 inferior incisors, and behind these, in male animals only, there is an additional alveolus for the tusk. The portion included on each side between the last incisor and first molar, forms a more or less sharp ridge, which constitutes the inferior interdental space or bars. Structure and development—Formed, like all the flat bones, by two compact plates separated by spongy tissue, the inferior maxilla is developed from two centres of ossification, which correspond to each branch, and which coalesce some time after birth. . 11.—The Hyoid Bone. The hyoid bone constitutes a small and special bony apparatus which serves to support the tongue, as well as the larynx and pharynx; its description is placed immediately after that of the bones of the head because of its connection with that region, it being situated between the two branches of the supermaxillary bone, and suspended to the base of the cra- nium in an oblique direction from above to below, and from before to behind. This apparatus is composed of seven distinct pieces, arranged in three series: a middle, constituted by a single bone, and named the body; two lateral, forming two quasi-parallel branches, to the extremities of which the body is articulated. Body.—The body of the hyoid resembles a fork with two prongs. It presents: 1, A middle part flattened above and below, and consequently pro- vided with a superior and an . inferior face ; 2, A single and ~ prolongation flattened sau sides, which is de-— tached from the middle part, and directed forward and downward to plunge into the muscular tissue of the tongue: this is the anterior appendiz of the hyoideal body ; Fig. 25. HYOID BONE. 1, 1, Superior extremity of the styloid bones; 2, Angle "8, Two lateral cornua, thyroid ” described by their posterior border; 3, 3, Styloid cornua, or great cornua, pro- bones; 4, 4, Extremities of the thyroid cornua; 5, jecting backwards and up- Articular surface of the body corresponding with the wards, articulating by their small branches; 6, Anterior appendix of the body; Lediities with 9 thyroi a 7, 7, Small branches, or styloid cornua, cartilage of the larynx, and offering, at their point of union with the middle part, two convex diarthrodial facets looking upwards, and corre- sponding with the styloid cornua. The body of the hyoid bone is developed ' by three centres of ossification, a middle, and two lateral for the cornua. Branches.—The three pieces composing these are articulated end to end, by means of a cartilaginous substance that joins them together; they are of very unequal dimensions. The first, which is in relation with the body, is of medium size, and is named the styloid cornu, small cornu, or small The second, termed the styloid nucleus, is the smallest. The third, the largest, constitutes the styloid process, or bone, or great branch. 1. The styloid cornu is a small cylindrical piece bearing a concave diarthrodial surface on its inferior extremity to unite it to the body ; it is very spongy, and is developed from two ossifying centres, one of which, the epiphysary, is for the inferior extremity. 2. The styloid nucleus, which is often absent, is imbedded in the uniting cartilaginous substance. Bt THE BONES. 8. The styloid bone, or great hyoideal branch, is long, thin, flattened on both sides, and directed obliquely from above to below, and before to behind ; it presents two faces, two borders, and two extremities. The faces —an external and internal—are marked by some few imprints. The anterior border is sharp and slightly concaye in its upper third. The posterior border is thicker, and is divided into two portions: a superior or horizontal, which is very short, and an inferior or vertical, much more extensive. ‘I'he angle they form at their point of junction presents a salient, and more or less roughened, tuberosity. The superior extremity is united to the hyoideal prolongation of the temporal bone by means of a cylindrical fibro-cartilage. By its inferior extremity, the styloid bone is united either to the styloid nucleus or the styloid cornu, forming a sharp elbow directed forwards. The styloid bone, developed from a single centre of ossification, is almost entirely formed of compact tissue. OF THE HEAD IN GENERAL, From the union of all the bones which constitute the cranium and face results a quadrangular pyramid, whose summit is inverted, which it is necessary to study as a whole. We will pass in review, successively, its — four faces, its base, and its summit. Anterior Face.—The anterior aspect of the head has the parietal, frontal, and nasal bones for its base. Superiorly, it inclines backwards and offers, on each side of the parietal ridges, two bulging surfaces which form part of the temporal fosse. For the remainder of its extent, it presents a plane surface which forms the base of the forehead and the middle portion of the face. Wide above, this surface gradually tapers to the extremity of the nasal spine. In well-formed animals, it is as straight and wide as possible. Posterior Face.—This face, which is extremely irregular, presents : above, the basilar process, the lacerated foramina, and the base of the tuberous portion of the temporal bones; then the intramaxillary space, and, at the bottom of this, the body of the sphenoid bone, vidian fissure, superior orifice of the subsphenoidal canal, sphenoidal process, palatine ridges, pterygoid bones, guttural openings of the nasal cavities separated from one another by the posterior border of the vomer, roof of the palate, incisive openings, and the incisive foramen. Lateral Faces.—These exhibit : behind, the external face of the maxillary branches ; before, a surface more or less convex, though sometimes hollow in old animals, presenting at its middle the inferior orifice of the maxillo- dental canal, and forming the base of the lateral parts of the face; above, the zygomatic ridge and arch, the orbit, and the temporal fossa. These . two cavities, in the formation of which many bones participate, have been hitherto merely indicated ; this is the place for giving them a more detailed deseription. The orbit or orbital cavity is irregularly circular in outline, and circumscribed by the orbital process of the frontal bone, the lachrymal and malar bones, and the summit of the zygomatic process. At the bottom, which shows the maxillary and orbital hiatus, it is confounded, in the skeleton, with the temporal fossa.' It lodges the globe of the eye and the muscles which move it, Some organs, accessory to the visual apparatus, 1 A fibrous membrane, the ocular sheath, isolates it from the temporal fossa in the majority of mammiferous animals, Only in Man and the quadrumana has the orbital — cavity complete bony walls, a THE HEAD, 55 such as the lachrymal gland and the membrana nictitans, are also contained in this cavity The erat fossa surmounts the orbit, and is incompletely separated from it by the orbital arch (or process). Oval in shape, lying obliquely from above to below, and from within outwards, on the sides of the cranium, the temporal fossa is limited, within, by the parietal ridge, and outwardly by the anterior border of the longitudinal root of the zygomatic process. It the temporal muscle. or superior extremity of the head.—This presents the occipital pro- tuberance, cervical tuberosity, occipital foramen, mastoidean ridge and fissures, styloid processes of the occipital bone, stylo-condyloid notches, and the con- dyles. On a lower plane, and behind, the curved portion of the posterior border of the maxillary bone is remarked. Summit.—Formed by the premaxillary bones and the body of the super- Fig. 26. SS pDy elie — LATERAL VIEW OF THE HORSE’S SKULL. 1, Premaxillary bone; 2, Upper incisors; 3, Upper canine teeth; 4, Superior maxillary bone; 5, Infraorbital foramen; 6, Superior maxillary spine; 7, Nasal bones; 8, Lachrymal bone; 9, Orbital cavity ; 10, Lachrymal fossa; 11, Malar bone ; 12, Upper molar teeth; 13, Frontal bone; 15, Zygomatic process, or arch ; 16, Parietal bone; 17, Occipital protuberance; 18, Occipital crest; 19, Occipital condyles; 20, Styloid processes; 21, Petrous bone; 22, Basilar process; 23, Condyle of inferior maxilla; 24, Parietal crest ; 25, Inferior maxilla; 26, Inferior molars ; 27, Anterior maxillary foramen; 28, Inferior canine teeth; 29, Inferior incisor teeth, maxilla, the summit supports tie incisor teeth, and presents a tuberosity more or less rounded, according to the age of the animal. In front, it is surmounted by the external opening of the nasal cavities; this opening, which is comprised between the external process of the premaxillary bones and the nasal spine, is divided in the fresh state into two orifices which constitute the nostrils. Internally, the head contains the nasal-fosse and the cranial cavity. These will be described when the apparatus belonging to them is noticed. (See the respiratory and nervous apparatus). DIFFERENTIAL CHARACTERS OF THE HEAD IN OTHER THAN SOLIPED ANIMALS. A, Heap or tux Ox, Surer, anp Goat.—1. Occipital bone.—The occipital bone in i does not show any anterior elbow. ‘The cervical tuberosity, or occipital 56 THE BONES. tuberance is obtuse, and gives rise on each side to the superior curved lines; in the mee. these curved lines are very salient and occupy the summit of the head. . = a The cbart rey. are ec a, ea H - a rs ort, and thick, has a ve in the middle of its external face ; ve is sometimes absent in the.Sheep anid Goat. ad ve The condyloid foramina are double, sometimes triple; the superior foramen does not pass directly into the cranium, but goes to a vast conduit that opens behind on the lateral margin of the occipital foramen, and which terminates in front by two ori on entering the parieto-temporal canal, the other opening on the external surface bone. The foramen lacerum is divided into an anterior and posterior foramen by the mastoid portion of the temporal bone. 2. Parietal bone.—The parietal bone in the Ox does not occupy the anterior aspect Fig. 27. OX’S HEAD; ANTERIOR FACE, 1, Mastoid process; 2, Superciliary, or supra-orbital foramen; 3, Zygoma; 4, Lachrymal bone; 5, Maxillary spine; 6, Inferior orifice of the supermaxillo-dental canal, of the head, but concurs with the occipital to form the base of the neck. It represents a very narrow osseous plate, elongated transversely, and curved at its two extremities, which descends into the temporal fossa to rest ave the sphenoid bone. There are no parietal ridges. The internal protuberance is only marked by a slight elevation of the internal plate; for the most part it belongs to the occipital bone. The parietal bone of the Ox is developed from three centres of ossification, and the middle nucleus is even primarily divided into lateral halves ; but these centres are consolidated with each other at an early period, as well as with the anterior portion of the occipital. It does not aid in the formation of the parieto-temporal canal, and is excavated internally by cavities which communicate with the frontal sinuses. , The parietal bone of the Sheep and Goat is relatively much larger than that of the Ox. It participates in the formation of the parieto-temporal canal, and has no sinuses, 3. Frontal bone.—-In ruminants, the frontal bone does not respond to the temporal — and palate bones. i In the Oz, this bone is extremely developed, by itself oceupying the anterior half of the nwards, ‘The basilar process, wide, — a un = 4 ‘4 ~ ~*~ - = THE HEAD. 57 ~ face, It is particularly distinguished by :—1, Its great thickness, 2, The osseous conical cores which sup the horns. These eminences, more or less long and curved, ot be pa perforated by foramina, and grooved by small vascular channels, are ; d outwards from each side of the bone, near the summit of the head. The — which form the orbital arches rest by their summits on the zygomatic bone. st supra-orbital foramen is transformed into a veritable and frequently multiple canal ; _ its anterior orifice opens into a vasculo-nervous groove, which ascends towards the base _ of the horns, and descends to near the lower border of the bone. Between this groove and the of the orbital arch is the frontal boss. The orbital foramen entirely belongs to this bone. The inferior border is deeply notched in its middle to receive the nasal bones; the frontal sinuses are prolonged into the horn-cores, the parietal bone, and even into the occipital bone. ___ In the Sheep and Goat, the frontal bone is relatively less extensive and strong than in _ the Ox; it does not ascend to the summit of the head, and the frontal sinuses are not eeeare veycnd its superior border. 4. bone.—In ruminants, the great ethmoidal cell is enor- : Fig. 28. iW ment of the sinuses around it. ‘This A character otherwise \ ult bone.—In the Oz, : \ i canal is absent. The sella turcica is deep, and the bony apes separating it from the a process is very high. The phenoidal canals are conv! into a single, but wide ; one. There are no notches in the ’ superior border for the e of : the internal carotid and spheno- - _ spinous arteries. That for the in- ferior maxil nerve is converted into a canal—the oval foramen. In the the osseous promi- nence that limits the sae eg fossa amina cury- peeeny forms a ig forwards and prolonged at its ex- * tremities into two points, which constitute the posterior clinoid pro- cesses } 6. Temporal bone—In the Oz, . RAM’S HEAD; ANTERIOR FACE. ay pai Goat, the tuberous portion 1, Occipital bone ; 2, Parietal bone; 3, Core of right of temporal bone is always con- frontal bone; 4, The left core covered by its horn; solidated with Let renege portion, 5, Superciliary foramen; 5’, Channel descending and the summit of the zygomatic from it; 6, Lachrymal bone; 7, Zygoma; 8, Nasal process only articulates with the one; 9, Supermaxillary bone; 10, Premaxillary malar bone. bone; 10’, Its internal process; 11, Incisive open- In the Oz, the condyle of the _ ing. zygomatic process is very wide and convex in every sense. The parieto-temporal canal is very large and entirely excavated in the temporal bone; its superior or internal extremity opens above the petrous portion in an excavation which represents the lateral cavity of the parietal protuberance in the ; at its inferior extremity it always shows several orifices. The mastoid process is very salient, and belongs to the squamous portion. The ¥ mastoid crest is confounded with the upper root of the zygomatic process; inferibrly, it _ ‘ 58 THE BONES. surpasses the mastoid ——- and is prolonged to the mastoid protuberance. The latter is very voluminous. The subuliform process is larger and stronger than in the Horse; and there is no mastoid fissure. In the Sheep and Goat, the mastoid process is scarcely distinct from the erest; and the mastoid portion of the bone is only at a late period consolidated with the petrous portion. Fig. 29. d Ox’s HEAD; POSTERIOR FACE. A, Parietal bone.—1, Occipital foramen ; 2, Occipital condyle; 3, Styloid process of that bone; 4, Condyloid foramina; 5, Mastoid process; 6, Mastoid protuber- ance; 7, Subuliform (temporal) process; 8, Hyoideal sheath; 9, Stylo-mastoid foramen; 10, External auditcry hiatus; 11, Inferior orifice of the parieto-tem- poral canal; 12, Temporal condyle; 13, Posterior foramen laceram; 14, Oval foramen; 17, Subsphenoidal process; 18, Orbital hiatus; 19, Optic foramen.— B, Frontal bone.—20, Superciliary foramen; 21, Orbital foramen; 22, Lachrymal protuberance.—c, Zygoma.—23, Pterygoid bone.—p, Palate bone.—24, Nasal fora- men; 25, Inferior orifice of the palatine canal.—r, Supermaxillary bone.—26, Maxillary spine.—G, Premaxillary bone.—27, Its internal process; 28, External process; 29, Incisive openings. 7. Supermaxillary bone.—In the Ox, Sheep, and Goat, the maxillary spine does not directly join the zygomatic crest ; a curved line, whose concavity is posterior, effects the union between these two parts. The inferior orifice of the supermaxillo-dental or infraorbital foramen is pierced above the first molar tooth. There is no fissure for the formation of the palatine canal. The cavity of the sinus is more spacious than in the Horse, and is prolonged (in the Ox only) between the two laminw of the palatine roof. There is no alveolus for the tusk. 8. Premazillary bone.—The inferior or principal portion of this bone is flattened before t is rarely and is g & 5 e : é E z a 3 Es 5 t I bstance. The Dew crest, very elevated, is formed altogether by the border of the palate bone, the ptery- the subsphenoidal process. There is tion for the sphenoidal sinuses; but, all that of the bone which enters the roof of the palate is hollowed by irre- eavities which communicate with the max- sinus of the sameside. The nasal foramen is very wide. In the Sheep and Goat, the maxil- shag do os esscar Haw them. ea s id bone.—The pterygoid of the Ox, al Coat is very large, polcloand an aper- between the sphenoid and palate bones. 11. ee ene jugal bone of Ruminants is very developed. The zygomatic crest is no formed by the posterior border of the bone, but is carried to the rior part of the external face, and runs el with the eyebrow. The summit is bifurcated, the anterior branch form- ing a buttress against the summit of the orbital of the frontal bone, while the posterior articulates with the temporal. 12. Lachrymal bone——The lachrymal bone, much more extensive than that of the Horse, forms in the bottom of the orbit an enormous protube- rance, hollowed internally by the maxillary sinus, and whose walls are so thin and fragile that the slightest jar is sufficient to cause their fracture (in the skeleton). It would be convenient to ica, ae it the lachrymal protuberance. In the ler ruminants, the inferior region of the exter- nal face shows a depression, the lachrymal fossa. 13. Nasal bones.—The nasal bones of the Ox are never consolidated with each other, nor yet with the neighbouring bones. The external border only comes in a to a small extent with the supermaxillary bone; the superior extremity is fixed in the notch of the inferior border of the frontal bone. At their inferior extremity, they each present a notch which divides them into two ts, In the Sheep and Goat the nasal spine is unifid, as in the Horse. 14. Turbinated bones—In the Oz, the eth- moidal turbinated bone is very small, and united to the nasal bone by the two borders of its osseous ate; its internal cavity entirely belongs to the tal sinus. The maxill turbinated | bone is very developed, and is joiréd to the bone which sustains it at a later period than in the Horse, The bony lamina of which it is composed is curved ttt 5 a1 i 1 Girard, who named this eminence the orbital protuberance, wrongly described it as belonging to the supermaxillary bone. THE HEAD. Fb abillet f MEDIAN AND VERTICAL SECTION OF THE OX’S HEAD. 1, Condyloid foramen; 1', Posterior ori- fice of the occipital lateral canal joining the parieto-temporal canal in front; 2, Internal auditory hiatus ; 3, Anterior foramen lacerum; 4, Pos- terior ditto; 5, Intra-cranial orifice of the parieto-temporal canal; 6, 6, Median bony plate separating the frontal sinuses; 7, Lamina which iso- lates the sphenoidal sinus; 8, Lamina partitioning the palatine portion of the maxillary sinuses; 9, Oval fora- men; 10, Optic fossa; 11, Vomer; 12, Pterygoid bone; 15, Large open- ing leading into the maxillary sinus, and which, in the fresh state, is closed by the pituitary membrane; 14, Max- illary turbinated bone; 15, Ethmoidal turbinated bone; 16, Great ethmoidal cell, 60 THE BONES. on itself in two differént directions : from before to behind by its posterior border, and behind to before by its anterior border. It is fixed to the supermaxillary bone by its middle part, through the medium of a particular bony lamina, and it very incompletely closes the excavation which concurs to form the maxillary sinus. In the skeleton there is also found behind, und at the base of this turbinated bone, a vast opening whieh — is totally closed in the fresh condition by the pituitary membrane. rolonged in its interior. In the smaller ruminants, the cavity of the is turbinated bone in a more complete manner than in the Ox, is closed — 7 transverse surface. extent of its posterior border. not the maxill The max sinus 15. Vomer.—This is a very large thin bone, resting only on the inferior balf of the median suture of the premaxillaries. HEAD OF THE PIG; ANTERIOR FACE. Summit of occipital pro- tuberance; 2, Parietal bone; 3, Frontal bone. —aA, Superciliary fora- men; A’ Channel des- cending from it.—4, Zygomatic process; 5, Zygoma; 6, Lachrymal bone.—B, Lachrymal canals,—7, Supermax- illary bone.—c, Inferior orifice of the supermax- illo-dental canal; 8, Nasal bone} 9, Pre- maxillary bone. 16. Premazxillary bone.—In the Oz, the inferior part of the posterior border is convex, and cannot rest on a hi plane by all its points at the sume time. The condyle is convex in its small diameter, and slightly concave laterally. The coronoid process is bent backwards and outwards, The body does not show any alveolus for the tusk, because this tooth is absent in these animals; but it is hollowed by eight alveoli for the incisor teeth. The two branches of the bone are never consolidated, but remain movable on each other during life. 17. Hyoid bone.—The hyoid bone of Ruminants is always composed of seven pieces; the styloid nucleus, whose presence is not constant in solipeds, is never absent in these, and * assumes the oe of a second small branch. The anterior appendix is very short and thick. B. Heap or rue Pic.—1. Occipital bone-—The occipital bone in this animal is not bent anteriorly; but the transverse protuberance representing the curyed lines forms, nevertheless, as in the Horse, the summit of the head; This eminence, which is excavated on both sides on the rior face, unites in front with the parietal bone, which abuts on the occipital at an acute angle. There is no external occipital protube properly speaking, and the styloid processes are very long an directed downwa 2. Parietal bone-—This bone is very thick, and deprived of an internal protuberance. The process concurring to cir- cumscribe the orbit is short, and joins neither the zygomatic or temporal bones; the orbital arch is completed by a liga- ment. The superciliary foramen, disposed as in the Ox, opens in front into a channel that descends to the nasal bones, The orbital foramen is formed by the frontal bone only. There is no mortice for the union of the frontal with the sphenoid bone, and the maxillary sinus is prolonged into the parietal bone. The frontal bone of the pig articulates with the super- maxillaries, 3. Frontal bone.—The frontal bone of the Pig is very thick and. short, and does not join the temporal or zygomatic bone ; tlie orbital arch is completed by a ligament. The superciliary foramen, dis as in the Ox, abuts in a channel that descends on the nasal bones. ‘The orbital foramen is formed by the frontal bone only. There is no mortice for the union of the frontal with the sphenoid bone ; and the frontal sinuses are prolonged into the parietal. The frontal bone of the Pig articulates with the supermaxillaries. 4. Sphenoid bone.—The sphenoid of the Pig is very short, but the subsphenoidal ere, are extraordinarily developed and flattened before and behind. There is no subsphenoidal canal, and the sella turcica is deep, and limited behind by.a very salient crest. A single canal replaces the’foramen rotundum and the great sphenoidal fissure, as in the Ox. The wings, slightly salient, are articulated by suture with the frontal bone. 5. Temporal bone.—The articular surface of this bone resembles that of rodents; it is not limited pag by a subcondyloid eminence, and, in addition, offers a wider TI 1e zygomatic process articulates with the jugal bone by the whole A crest leading from the external auditory hiatus to the THE HEAD. mastoid — replaces the mastoid process. 4 with the superior root of the zygomatic process. The projection formed by the mastoid protuberance is enormous, The subuliform — is little marked, and there is no hyoideal prolongation or parieto-temporal canal. Fig. 32. _ 6. Supermazxillary bone.—In the Pig, the ex- ternal surface of this bone is hollowed in its middle, a oem in front a voluminous relief formed alveolus of the canine tooth. The cavity is entirely formed in the supermaxilla. There is no alveolar tuberosity, and the interdental space is very short, while the cavity for the sinus is little The lower orifice of the palatine canal is even pierced in the substance of the super- maxilla, 7. Premazillary bone—The external process of the premaxillary bone is very long and wide at its base, and consolidated with the nasal bone for about the upper two-thirds of its length. There is no incisive foramen or cavity for the tusk. The — _ openings are oval. the head, a thick and very remarkable trifid pro- jection or mamelon. 9. Pterygoid bone—See the description of the 10. Zygomatic bone.—The summit of this bone in the “i 3 is flattened on each side, and divided i nanches, between which is wedged the summit of the zygomatic process; the anterior branch is very short, and does not join the frontal much longer and less fragile. 14. Inferior Mazilla.—A straight line leadin from the greater axis of the alveoli of the molar weal not traverse the posterior border of the maxillary branches; the bottom of these alveoli corresponds to the relief on the inner face. The cond bn is ore wide. There is no neck; the interdental spaces are very short ; and the maxillo-dental canal opens meninty by multiple orifices. 15. Hyoid bone.—The body is voluminous and deprived of an ape short and consoli the small branches are 61 The mastoid crest is, as in the Ox, HEAD OF THE PIG ; POSTERIOR FACE. “ 1, Occipital protuberance; 2, Occi- pital foramen; 3, Occipital con- dyle; 4, Condyloid foramen; 5, Basilar process ; 6, 6, Mastoid crest; 7, Styloid process of the occipital bone; 8, Articular surface of the temporal bone; 9, Mastoid protu- berance; 10, Foramen lacerum; 11, Subsphenoidal process — external wing of pterygoid process; 12, Palatine crest ; 13, Pterygoid bone —internal wing of the pterygoid process; 14, Inferior orifice of the palatine canal; 15, 15, Incisive openings. ted with the body; while the large branches, curved like an 8, are very thin, and are united to the small branches and the temporal bone no longer by fibro- neti 7 but by veritable yellow elastic ligaments. C. Heap or Carnrvora.—l, 4 Occipital bone.—The eminence which constitutes tho 62 THE BONES. origin of the superior curved lines is very elevated and strong. The cervical tu of the external occipital protuberance is absent or little marked; the styloid processes are short, and well deserve the name of jugular eminences. The foramen lacerum is divided into two portions by the mastoid protuberance, and the basilar process is wide, long, and thick, and hollowed on the side by a channel that joins a similar one in the temporal bone to form a large venous canal. This last communicates, behind, with the posterior foramen lacerum, and opens, in front, in the cranium, where it is continuous with the cavernous groove of the sphenoid. The anterior angle forms a very prominence, which is deeply fixed into the parietal bone, aud partly coustitutes the internal protuberance of that bone. 2. Parietal bone.—In the Dog the parietal bone, formed by two ossific centres only, is distinguished by the great development of the ridges and the parietal protuberance. This last, constituted in part by the occipital bone, does not show any lateral excavations at its base; they are carried lower, near the summit of the petrous process, on the sides of the occipital bone. The parieto-temporal canals are continued, notwi ’ to the base of the protuberance, which they traverse, to Fig. 33. open into each other in its interior. In the Cat there are scarcely any parietal crests, and the internal protuberance is replaced by two trans- verse bony plates which separate the cavity of the cerebrum from that of the cerebellum. 8. Frontal bone.—In carnivora, the external face of this bone presents in its middle a more or Jess marked superciliary foramen, or mortice on the inner face. bone is united with the supermaxillaries, 4. Ethmoid bone.—The ethmoidal fossa is very deep, and the cells very developed and diverticulated. “The per- pendicular lamina is at a late period consolidated with the sphenoid bone. 5. Sphenoid bone.—The superior sphenoid of the Dog is very short, and bears, laterally, two wide wings which ascend to the temporal fossa ; they correspond to those of the sphenoid bone in Man. The inferior sphenoid is, on the contrary, very narrow, and its lateral prolongations, or pro- cesses of Ingrassias, are reduced to very small proportions. The sub-sphenoidal or pterygoid process is very short, and the canal is single, and communicates with the foramen rotundum. . The pituitary fossa is shallow, limited behind o and before by the posterior clinoid and anterior clinoid HEAD OF DOG; ANTERIOR processes, so named because of their being compared to the FACE. four posts of an ancient bed. The supersphenoidal canals 1, Occipital protuberance; 2, ®t€ only two in number: one represents the great sphenoidal de- pression. The orbital arch is incomplete, and there is no~ Median spur of the occi- . pital bone; 3, Parietal bone; 4, Origin of the pa- rietal crests; 5, Zygomatic process of the temporal bone ; 6, Frontal bone; 6’, Orbital process; 7, Zy- goma; 8, Lachrymal bone; 9, Nasal bone; 10, Super- maxilla; 11, Inferior ori- fice of the supermaxillo- dental canal; 12, Pre- maxillary bone. fissure, the other the round foramen. The carotid noteh, joining a similar one in the temporal bone, forms an open- ing which may be designated the carotid foramen, because it gives passage to an extremely remarkable leop the in- ternal carotid artery describes after passing through the carotid canal. The oval foramen is the same as in the Ox. In the Cat there is the same disposition, with the ex- ception of no sphenoidal canal or carotid notch being present. 6. Temporal bone-—In the curnivora, the arti sur- face of. the zygomatic process merely forms a glenoid cavity, into which the condyle of thé maxillary bone exactly fits. The temporal bone in these animals is also distinguished by the width of the external auditory canal, the absence of a hyoid uo aan the small development of the mastoid and sty oid processes, the enormous yolume of the mastoid protuberance, and the presence of two particular canals which cannot be traced in the other animals. One of them, the carotid canal, traverses the mastoid portion, and joins, superiorly, the venous canal which passes between the basilar process and the temporal bone; by its inferior extremity it joins the carotid foramen which itself penetrates the cranium, a little beyond the venous canal just mentioned, The other conduit is pierced in the petrous portion immediately above the carotid canal; it affords a passage to the fifth pair of encephalic nerves. Ty, + ~ Eee Tl — aie aa THE HEAD. 63 7. Supermazillary bone.—In carnivora, this bone is very short; its anterior border analogous tothe nasal spine of Man. It alone furnishes the alveolus _ offers a long process of the tusk. The palatine canal, pierced entirely in the bone of that name, nevertheless ‘Opens, bone. 8. Premazillary bone.—Of little size, the "cape raed its inferior extremity, at the junction of the supermaxillary with the palate maxil sinus is not very spacious, and there is no maxillary spine. Fig. 34, of carnivora has no incisive foramen or alveolar cavity for rep pain tooth. The incisive openings are the same as a Oe Pi bone.—In the carnivora, the palate bones are of great extent in their proper palatine portion, They have no share in the formation of the sphenoidal siuuses, but furnish a small excavation to the maxillary sinuses. 10. Pterygoid bone.—This bone is very strong in car- ee ote age in cnr ae - Mina! 1. Zygoma.—The zygoma of the an t only articulates with the supermaxillary bone ~ its base. The crest describes a curve backw and the summit com- ports itself as in the Pig. 12. bone.—This bone in carnivora is ex- tremely small. Its external face entirely belongs to the orbit, and does not cowie recngeg the margin of that ‘ossa, bey it has no 13. Nasal bone—The two bones of the nose are litile developed, and are wider below than above; they have no nasal prolongation, but offer instead a semicircular 14. Turbinated bones.— These bones in tlie Dog and Cat are particularly distinguished for their numerous convo- lutions. Neither participate in the formation of the frontal or maxillary sinuses; the latter is not in any way closed _ by the maxillary turbinated bone, but opens into the nasal cavity by a large gaping aperture. _ 15. Inferior mazillary bone.—In carnivora, this is hollowed at the point corresponding to the insertion of the masseter muscle into a somewhat deep fossa. The — border is disposed as in ruminants, and below condyle has a very marked tuberosity. The condyle treble. There are no interdentul spaces, nor excavated surface on the inner face of the branches; aud the latter are never consolidated. 16. Hyoid bone.—'The three picces composing the body of the hyoid in early life are never consolidated in the adult animal, but always rema‘n isolated, as in Mun. The middle piece has no anterior appendix; the fibro- cartilages uniting the styloid portions to each other and to the temporal bone are very long and flexible. COMPARISON OF THE HEAD OF MAN WITH THAT OF THE DOMESTICATED ANIMALS, 1. Occipital bone.—The occipital of Man is large, flat, like a shell, and the external protuberance is slightly developed, and united by a ridge to the occipital , which is relatively very wide. Two series of ridges arise from the external protuberance and pass towards the circumference of the bone; these are the superior and inferior curved or semicircular lines. There is an anterior and a posterior condyloid fossa pierced by a DOG’S HEAD ; POSTERIOR FACE, 1, Occipital protuberance; 2, Occipital foramen; 3, Occi- pital condyle; 4, Condyloid foramen; 5, Styloid process of the occipital; 6, Mastoid protuberance; 7, Concave temporo-maxillary articular surface ; 8, Supercondy- loid eminence; 9, Inferior orifice of the parieto-tem- poral canal; 10, Lacer- ated foramen, posterior; 11, Ditto, anterior.—On the op- posite side at a is shown the orifice communicating with the Eustachian tube and the tympanum; at b the passage for the carotid convolution.—12, Body of the sphenoid; 13, Oval fora- men; 14, Inferior orifice of the subsphenoidal canal; 15, Pterygoid bone; 16, Nasal surface of the palate bone; 17, Palatine surface of the same; 18, Vomer; 19, Supermaxillary bone; 20, Incisive opening. foramen at the bottom; and the jugular eminences, wide and slightly prominent, re- place the styloid processes of the domesticated animals. The internal face of the occipital of Man corresponds with the cerebrum and f/f - =~ ee SS 64 THE BONES, cerebellum ; and for this purpose it shows four fossm, distinguished into superior or cerebral, and inferior or cerebellar, These foss@ are separated by a crucial whose most developed portion forms the internal occipital protuberance. The union of the occipital with the parietal bones constitutes the lambdoidal suture. At the poiut where this bone meets the purietal and the squamous portion of the temporal, is found, in the infant, the lateral posterior fontanella. 2. Parietal bones.—The parietals are always isolated in early life, and sometimes consolidated with each other at the adult age. They are very large, quadrilateral, and occupy the summit and sides of the cranium. Fig. 35. — of the orbit, At the union of the wings with the goid processes; their internal branch represents the pterygoid bones of animals. ? FRONT VIEW OF THE HUMAN CRANIUM, Frontal bone; 2, Nasal tuberosity ; 3, Supra-orbital ridge; 4, Optic foramen; 5, Sphenoidal fissure ; 6, Spheno-maxillary fissure; 7, Lachrymal fossa; 8, Opening of the nose divided by the vomer; 9, Infra-orbital foramen; 10, Malar bone; 11, Symphysis of the lower jaw; 12, Mental foramen; 13, Ramus of the lower jaw; 14, Parie- tal bone; 15, Coronal suture; 16, Temporal bone; 17, Squamous suture ; 18, Upper part of the great ala of the sphenoid bone; 19, Com- mencement of the temporal ridge ; 20, Zygoma of the temporal bone, concurring to form the temporal arch; 21, Mastoid process. is no subsphenoidal canal. The two lesser wings are very thin and triangular, and visible only on the superior sur- face of the bone; they constitute the processes of Ingrassias. On the internal face of the bone are found :—1, A deep pituitary fossa, limited by The parietal crests are absent, but are a in certain individuals, by two faintly curved lines situated a little above the inferior border of the bone. The middle portion of the external face is very convex. On the internal face there is no parietal pro- tuberance, but in its stead the internal occipital protuberance. It also exhibits ramous channels, which in disposition are analogous to the ribs a fig-leaf; as well as the parietal fossa which cor- responds to the parietal eminence. . 8. Frontal are a — a of Man forms the u of the face and the anterior portion of ony ty aay Convex from behind forward, then vertical in its upper three-fourths, the bone sud- denly bends at the orbits, so as to become hori- zontal in its lower fourth. . The external face offers, above the forehead, two lateral frontal eminences, and above the nose, 2 middle frontal boss. To the right and left of the latter are two salient arches, the supraorbital ridges. The internal face entirely belongs to the cranial cavity. It offers on the median line, the saggital groove terminated by a frontal crest; and on each — side of this line the frontal fosse, corresponding ~ to the eminences of that name, and orbital bosses to match the orbital roofs. There is no mortice for the articulation of the sphenoid bone, On the middle portion of the superior frontal border, in young persons, is the anterior angle of the anterior fontanella, The anterior border ex- hibits three superciliary foramina and the orbital arches. 4. Ethmoid bone.—In Man, the external face of the lateral masses, formed by a very thin lamina, termed the os planum or lamina papyrauce, belongs to the internal wall of the orbit. 5. Sphenoid bone.—This is distinguished, in Man, into a body and four wings, two large and two small, The inferior surface of the body offers nothing remarkable, except the presence of a conical pro- longation named the beak (rostrum) of the sphe- noid. The external face of the greater wings forms part of the og ee fossa, as also the external wall y are detached two bifid pone ere four clinoid processes; 2, An optic fossa, shallow, showing very short optic canals trans- formed into foramina; 8, The sphenoidal fissure, which replaces the great super- sphenoidal canal in the Horse; 4, The great foramen rotundum ; 5, The internal face of the wings, much excavated ; 6, The foramen ovale, which transmits the inferior maxillary nerve; 7, The small foramen rotundum that lodges the spheno-spinous artery. THE HEAD. 65 _ 6. Temporal bone.—In tl:e squamous portion of the temporal bone of Man, the zygomatic process only rests on the malar bone, as in ruminants. The glenoid- cavity is concave in every sense, and divided into two by an opening named the fissura Glaseri ; the anterior portion ouly is articular, the posterior, lying against the external auditory canal, does not belong to the articulation ; it corresponds to the supracondyloid eminence of the Horse. The tuberous portion is consolidated with the squamous. It is divided into a mastoid and a pyramidal portion; the latter comprises, in its turn, the petrous tympanic portions. The mastoid , ube the rance, and superior border of rtion corresponds to the mastoid process, petrous bone in the Horse. It presents and pamela al mastoid process; above this is the mastoid canal; and above and behind it, the groove; the pyramid forming a con- projection in the interior of the cra- nium. The styloid process or bone is altogether _ separate from the otlier pieces of the hyoid, and in the adult is consolidated with the temporal bone. 7. Supermazilla.—In Man the premaxilla is no longer found independent, the centre which forms it coalescing with the supermaxillary bone. The supermaxilla of Man concurs, for tlie greater part of its extent, to form the floor of the orbit; it is also divided into three faces: an external or facial, a superior or orbital, and an internal or naso-palatine. The external face ts, from before to behind: 1, A small sen into which is inserted the myrtiform muscle; 2, The infraorbital, or canine fossa, showing the inferior orifice of the infraorbital canal; 3, A crest corresponding tothe maxillary spine of solipeds; 4, The alveolar tuberosity. This face carries, in front, a prolongation that forms the ascending process, also named, be- eause of its relation, the ironto-nasal process, The superior or orbital face offers a fissure which precedes the infraorbital canal, and, outwards, the malar process. The internal face is divided by the palatine process. It shows, in front, the half of the anterior nasal spine and a groove which participates in the formation of the in- cisive canal. 8. Palate bone.—The palate bone of Man is formed of two osscous laminew: one horizontal, the other vertical, which are joined at a right angle. The first part presents: one-half of the jor nasal spine, which is altogether rudi- mentary, or even null in animals; the orifice of the posterior palatine canal, which belongs entirely to the palate bone ; the pterygo-palatine ; lastly, the pterygoid process, which represents the pterygoid bone of animals. The vertical portion forms the external wall of the nasal cavities by its internal face, and by its ex- ternal face — the formation of the ic or tem ossa. a See .—This offers three faces. The or cutaneous, serves as a base for the most salient part of the cheek. The superior, or orbital, forms part of the external wall and floor of the orbit; it belongs to a long apophysis, the orbital ress, Which rests on the sphenoid and frontal Fig. 36. EXTERNAL OR BASILAR SURFACE OF THE BASE OF THE HUMAN SKULL. i, 1, The bony palate; 2, Incisive, or anterior palatine foramen; 3, Palatine process of palate bone, with the pos- terior palatine foramen; 4, Palate spine with transverse ridge ; 5, Vomer; 6, Internal pterygoid palate; 7, Sca- phoid fossa; 8, External pterygoid plate, with fossa; 9, Zygomatic fossa ; 10, Basilar process of occipital bone ; 11, Foramen magnum; 14, Glenoid fossa; 15, Meatus auditorius exter- nus; 16, Foramen lacerum anterius ; 17, Carotid foramen of left side; 18, Foramen lacerum posterius, or jugular foramen; 19, Styloid process; 20, Stylo-mastoid foramen, with jugular tubercle and digastric fossa; 21, Mas- toid process; 22, Occipital bone; 23, Posterior condyloid fossa, nes. The posterior face is smooth and concave behind, where it aids to form the temporal fossa; in front it is uneven, and articulates with the supermaxilla. The posterior, or masseteric border, unites with the zygomatic process of the temporal bone. 10. Lachrymal bone.—This bone is also called the os unguis in Man, because of its likeness to the nail in shape and tenuity. It is entirely lodged in the orbit, and its F OE - — i A i i ee ay, 66 THE BONES. external face is divided into two portions by a vertical crest; the portion situated in front of this crest forms part of the lachrymal channel. By its internal face, the bone limits, outwardly, the bottom of the nasal cavities, and covers the anterior cells of the ethmoid ; by its posterior border, within the orbit, it articulates with the os planum of the ethmoid. - 11. Nasal bone—The proper bones of the nose of Man exhibit a great analogy to those of the Dog. They do not. possess a nasal prolongation, and they articulate with the lateral cartilage of the nose. 12. Vomer.—The same general form and relations as in solipeds, i 13. Inferior maxillary bone.—This bone in Man is in shape somewhat like a horse- shoe. It is nearly of the same width throughout its whole extent. The symphysis is vertical—a character peculiar to Man. Below this symphysis is a trian; pro, . the mental eminence. The genial surface of the Horse is replaced by four little tubercles termed the genial processes. The alveoli of the molar teeth form a great [agpeen= on the inner face of the bone. The mylo-hyoid ridge is very developed. The superior orifice of the dental canal is covered by a little sharp lamina. From this orifice begins the mylo-hyoidean groove. The coronoid process is short; the condyle is bent towards the median line, and the sigmoid notch is wide and shallow. The superior border contains fourteen or sixteen alveoli. Articie II1.—Tue Torax. The thorax represents a conoid cage, elongated from before to behind, suspended under the vertebre of the dorsal region, and destined to contain the principal organs of respiration and circulation. It is composed of bony arches named ribs, thirty-six in number—eighteen on each side—and a rye piece, the sternum, which serves for the direct or indirect support of the inferior extremities of the ribs. THE BONES OF THE THORAX IN PARTICULAR. 1. Sternum of the Horse. 4 This is an osteo-cartilaginous body, elongated from before backwards, flattened on each side in two-thirds of its anterior extent, and from above to below in its posterior third, slightly curved on itself, and situated beneath the thorax in an oblique direction from above to below, and before to behind. It offers for study, a superior face, two lateral faces, three borders, and two extremities. Fig. 37. THE STERNUM. 1, The cervical prolongation (or cariniform cartilage) ; 2, The xiphoid appendage (or ensiform cartilage; 3, 3, Cavities for the articulation of the sternal cartilages; 4, Inferior border. — Faces.—T he superior face, aig concave longitudinally, represents an isoscelated, lengthened triangle, the summit of which is directed forwards; it constitutes the floor of the thoracic cavity. Each lateral face comprises two parts—a superior and an inferior, The first shows eight diarthrodial ~ « THE THORAX, 67 se ities, which receive the inferior extremity of the cartilages of the true ribs. These cavities are elongated vertically, and draw closer to each other “than be, extend backwards. The inferior part, which is more extensive before d, offers to the powerful pectoral muscles a large surface for aa Borders. —The two lateral borders separate the superior from the lateral Pics. they are situated above the diarthrodial cavities, are united anteriorly, and each gives attachment to a fibrous band. The inferior border is opposite _ the superior face ; convex, thin, and very prominent in its anterior two-thirds, it somewhat resembles the keel of a ship. Extremities.—The anterior flattened on each side and curved upwards, exceeds to some extent the first articular cavity of the lateral faces, and in _ this way constitutes the cervical prolongation of the sternum. The posterior extremity is flattened superiorly and inferiorly, and forms a large cartila- ginous plate, very thin, concave above, convex below, which has received the name of the abdominal ‘prolongation (ensiform cartilage) or xiphoid appendage. Structure and development.—The sternum is one of the penta of the skeleton which do not submit to complete osseous transformation. It is developed, in solipeds, from six single centres of spongy substance, ranged one behind the other, like beads on a string. These centres never coalesce to form a solid piece, but remain separated, during the life of the animal, by the ive cartilaginous mass. The latter constitutes the entire anterior pro- of the bone and its carina, as well as the xiphoid appendage. When _ these parts of the sternum become ossified, which is rare, it is only partially. 2. The Ribs. As has been already noticed, on each side of the thorax eighteen ribs are counted. These are nearly parallel to each other, and separated by the intervals termed the intercostal spaces. Attached by their superior extremity to the vertebra of the dorsal region, these bones terminate at their inferior extremity by an elastic and flexible prolongation, named the costal cartilage, by means of which they are brought into direct or indirect relations with the sternum. The characters common to all the ribs will be first noticed, then the special features which serve to distinguish them from each other, and, lastly, the differences they exhibit in other than soliped animals. Shad CitanacTers Common To ALL THE Rrss.—These will be studied from a t of view, first in the rib itself, and then in its cartilage. ee Peeriencn of a typical rib.—A rib is an elongated symmetrical bone, oblique Gat he above to below, and from before to behind, flattened on both _ sides, curved like a bow, and twisted on itself in such a fashion that its two extremities cannot rest on the same horizontal plane. It is divided into a — middle and two extremities. —This offers two faces and two borders. The external face is convex, and hollowed by a wide groove in its anterior half; it shows _ superiorly, towards the point corresponding to the angle of the rib in Man, some tubercles and muscular imprints. ‘The internal face is concave and _ smooth, and covered by the pleura, which separates it from the lungs. The _ anterior border is concave, thin, and sharp; the posterior, convex, thick, and | overed with rugged eminences, is channeled inwardly by a vasculo-nervous ogee ns gh disappears near the middle of the rib. —The superior has two eminences, a head and a tuberosity, filth aor serve ar the support of the rib against the spine. The first is formed 4 by two articular demi-facets, placed one before the other, and separated by a R F 2 68 THE BONES. ve for ligamentous insertion; it is isolated from the tuberosity bya — Reisow part, named the siachy wehki MaMa ar Fedited Situ for the implanta- tion of a ligament. The second, situated behind the head, and smaller than — it, is provided with imprints on its margin, and presents an almost flat — diarthrodial facet at the summit. Each rib articulates by its head and — tuberosity with two dorsal vertebre ; the head is received into the inter-— Fig. 38, 7, Groove on the external face; 8, Vasculo-nervous groove of the posterior — border; 9, Prolonging cartilage; 10, A, Articular tuberosity for union with the = sternum. = vertebral articular cavity; the tuberosity corresponds, by its facet, to the zi transverse process of the posterior vertebra. ha The inferior extremity is tuberous and excavated by a shallow ca = irregular at the bottom, for the reception of the upper end of the costal : cartilage. : Structure and development.—The ribs are very spongy bones, especially 4 TYPICAL RIBS OF THE HORSE. += A, Inner face of the fifth sternal rib; B, External face of the first asternal rib.— ys 1, Head of the rib; 2, Its fissure; 3, Neck; 4, Tuberosity; 5, Articular facet; 4 6, Scabrous fossa for the insertion of the interosseous costo-transverse ligament ; s 4 77 THE THORAX. 69 ‘in their inferior moiety, and are developed at a very early period by three _ centres of ossification: a principal for the middle portion and inferior _ extremity, and two complementary for the head and tuberosity. 2. ~ Description of a typical costal cartilage—The costal cartilage very _ evidently represents the inferior rib in birds; it is a cylindrical piece, : y compressed at the sides, and round and smooth on its faces and borders. By its superior extremity, it is united to the rib it serves to lengthen, and forms with it an angle more or less obtuse, opening in front. _ At its inferior extremity, it is terminated by an articular enlarge- - ment, or by a blunt point. In youth, the costal prolongations are entirely — com of cartilaginous matter, but they are soon invaded by ossification > so that in the adult animal they are already transformed into a spongy substance, with large areole which remain during life surrounded by a thin layer of cartilage. B. Sprectrric Cuaracrenrs or tHe Rrss.—The ribs, like the vertebrae of each region of the spine, have received numerical designations of first, second, third, ete., computing them from before to behind. (See Fig. 1.) Owing to the pre- sence of an altogether essential characteristic, they are naturally divided into two great categories: the sternal or true ribs, and the asternal or false ribs. The sternal ribs, numbering eight (the first eight), have their cartilages terminating inferiorly by an articular enlargement, which corresponds to one of the lateral cavities of the sternum, and brings the true ribs into direct contact with this portion of the skeleton, The asternal ribs, ten in number, rest on each other—the last on the seventeenth, this on the sixteenth, and so on—by the inferior extremity of their cartilage, which ends in a blunt point. The cartilage of the first false rib is united somewhat closely to the last sternal rib, and it is through the medium of this that all the asternal ribs lie indirectly on the sternum. If, however, the ribs are considered altogether, with regard to the differen- tial characters presented by them in their length, width, and degree of incurvation, it will be noted: 1, That their length increases from the first to the ninth, and from this diminishes progressively to the last; 2, That the same progressive increase and decrease exists in the cartilages; 3, That they become gradually wider from the first to the sixth inclusive, and then con- tract by degrees until the eighteenth is reached ; 4, That the curve described _by each is shorter and more marked as the rib is situated more behind, It may be added that the channel on the external face is less conspicuous in ¢ 8 E-FOOT, OR HAND.—1. Carpal bones.—The carpus of the that of Man, contains eight bones—four in each of the The second bone of the upper row corresponds with the ulna, to a small extent with the radius. In the bones of the lower it is observed that the first corresponds with the two external _ mMetacarpals, the second with the great internal metage* pal, the third with the preceding and the small internal metacarpait. The fourth, _ or trapezium, terminates inferiorly by a blunt point, and has no _ Telations with the metacarpal bones, because the thumb is entirely _ undeveloped in this ani ) 1, Olecranon ; 2, Body of the ulna; 3, Body of the radius; 4, 5, 6, First, second, and third bones of the upper row of the carpus; 7, 8, and second bones of the lower row; 9, Rudimentary metacar- ae 10, Principal metacarpals; 11, External digit; 12, Internal F iL 87 FORE-ARM AND FOOT OF THE OX; FRONT VIEW. gs THE BONES. In the Cat there are also eight bones,. The second, or pyramidalis, of the upper row — is very developed ; it occupies all the external border of the carpus, and articulates with the ulna the first bone of the second row, and the first metacarpal. The are! bone, elongated, prismatic, and thickened at its extremities, offers in front two articular facets, one to correspond with the ulna, the other to join the ig therm The bones of the inferior row decrease in thickness from the first to the and correspond: the first, to the first and second metacarpals; the second, to the ae . of the third digit; the third, to that of the fourth digit; fourth, to the metacarpal of the thumb. In the Dog there are only seven bones, as, the seaphoid and semilunar bones are united, but the general di is the same as that in the Cat. Lastly, in the Ox and Sheep the carpus is only com of six bones: four in the upper row, and only two in lower, where the os magnum and trapezoides are consolida’ The supercarpal bone has no groove for gliding, and we alis articulates with the radius and ecubitus. nes of the lower row only articulate with the metacarpal bone. (Professor Gobaux, in 1865, specimens which go to prove that of the two bones of lower row in the carpus of Ruminants, the internal represents two; so that these animals actually have carpal bones like the Horse.) 2. Metacarpal bones—The number of metacarpal bones varies much in the domesticated animals :— In the Carnivora thereare. . . . . 5 In the Pigthereare. . . .... 4 In Ruminants there are. . . . .. 2 The five metacarpals of the Dog and Cat articulate with each other, at their superior extremities, by lateral facets; 3 they offer, at their inferior extremity, a condyle prolonged backwards by an articular surface resembling that of the — Horse. The middle two are always longer than the two lateral. The smallest belongs to the fifth digit, or thumb, and is terminated inferiorly by a trochlea. The four metacarpals of the Pig articulate with each other, 7 as in the Carnivora. The second and third are than the first and fourth. The fifth metacarpal is not developed. 2 In Ruminants the metacarpal bones are two in number: | a principal, which itself results from the consolidation of the second and third metacarpals, and another altogether rudi- mentary, ; The principal metacarpal is channeled on its anterior face, and for its whole length, by a deep vascular fissure—a trace — FORE-ARM AND FOOT OF of the primitive separation of the bone in two pieces. This THE DOG; ANTERIOR fissure presents, inferiorly, the anterior orifice of a canal that FACE. completely traverses the bone. The posterior face is also 1, First digit; 2, Second marked by a very slight longitudinal groove. The superior JeEeh : ibe digit; 3, Third digit ; 4, Yourth digit; 5, Thumb; 6, 7, 8, 9, First second, third, and fourth bones of the lower row of carpal bones; 10, 11, First and second bones of the upper row; 12, Supercarpal bone; 13, Body of the ulna; 14, Apex of the olecranon ; 15, Beak of the olecra- non; 16, Body of the radius, extremity exhibits, externally and posteriorly, a single diar- throdial facet for the articulation of the rudimentary meta- carpal. The inferior extremity is divided by a deep notch into two articular surfaces, which together resemble the angle surface in the Horse; each corresponds to one of the di ; the external is always smaller than the internal. In the foetus, the two long bones that form the great metacarpal are simply laid together, and their medullary canals are — rated from each other by the double partition which ts from this apposition ; after their coalescence, however, the titions are completely destroyed by resorption, and in a time there is only a single medullary for the entire bone, The rudimentary metaca is only a small osseous stylet, articulating, by a diarthrodial facet, behind and to the outside of the superior extremity of the principal metacarpal; it is sometimes absent in the Sheep and Goat. THE ANTERIOR LIMBS. 89 8. Digital Region.—In the domesticated animals the number of complete digits is as . Warhivora .. 25. BROS ee; Ba neice esis ee i ‘4. ents ard Ars 8 five digits of the Dog and Cat are exactly analogous to those of Man. Thus, the corresponds to the auricularis, the second to the aunularis, the third to the the fourth to the index, and the internal to the thumb.—The latter, very small, two phalanges and does not come into contact with the ground. Each of the is composed: 1, Of a first phalanx, to which are annexed two sesamoids; second phalanx, which yet oe a veritable long bone; 3, A conical phalan- , bent iGaaecnde, and hollowed at its base by a circular groove, in which the matrix of the claw. The small sesamoid (or navicular bone) is absent, but ‘ by a inence of the ungueal phalanx. The auricularis and index are alike, and not so as the annularis and medius, which are the same in length. , age four complete digits articulating from the metacarpals; the thumb is - absent. index and auricularis, or fourth and fifth digits, are short, and do not usually rest on the ground. Ruminants certainly possess four digits, but only two are perfect—the medius and annularis—and these articulate with the inferior extremity of the principal metacarpal. The two others—the index and auricularis—are in a rudimentary condition, and are represented by two small bones situated above and behind the metacarpo-phalangeal In the Ox, Sheep, and Goat, each of the perfect digits comprises three phalanges and three sesamoids. The phalanz fairly represents the moiety Fig. 54. are repeated in the other two It is also remarked in all the plia- ‘ bones, that the external articular facet of the extremities is always larger than the larger Wig haghaderse Sy ths eae e internal, They articulate with each other, and with the first by small diarthrodial facets. cand nz is hollowed internally solipeds, This phalanx has no complemen fibro-cartilage, al process, or retrossal ad nenece, nor yet a cavity of insertion on the sides of the pyramidal eminence. The semilunar crest is by an obtuse, thick, and rugged relief, w upies quite the posterior limit of the inferior face of the bone. Three large ‘anaagel gamed ont third Lewgriry ee a HUMAN SCAPULA$ EXTERNAL ASPECT, } eminence, and one tow : , ; ee as pete: vies ‘Tiny orn, Sermpoess fam, &, Tntcoom in the i of the bone, a vast sinus, giving scapular notch 35 Anterior or axil ry | fise to several yascularcanals which open on the erder+ 6. Head of the scapular and _ surface, There is only one foramen at the base of glenoid cavity ; 7, Inferior angle; 8 rm s ‘ 2 ) ES > “s _the pyramidal eminenceinthesmaller Ruminants. Neck of the scapula; 9, Posterior border; 10, Spine; 11, Triangular COMPARISON OF THE THORACIO LIMB OF MAN WITH smooth surface, over which the tendon THAT OF THE DOMESTICATED ANIMALS. of the trapezius glides, with the tuber- ___ A. Suor~per.—The shoulder of man (fig. 54) culuy spinw scapula between it and “has for its base two well-developed bones, the 10; 12, Acromion process; 13, Nutrient scapula and clavicle. The scapula is moredis- foramen ; 14, Coracoid process. tinetly tri than that of all the domesti- cated ani ; its vertebral border is also more extensive. The scapular spine, very 90 THE BONES. elevated, is followed by an acromion whose extremity reaches to above the humeral articulation. The latter is separated from the remainder of the by a | constriction called the pedicle of the acromion. . The coracoid process is volu nd resembles a semi-flexed pg The. clavicle extends from the acromion to the sternum; _ it is flattened above and below, and flexed like an italic S. This inflexion of the clavicle is more pronounced in the male than the female. wer B,. Arm,—The humerus of Man is much longer than that of animals. Its diner is prismatic and divisible into three faces; the deltoid imprint has the form of a V wi its point directed downwards. The voluminous articular head is turned inwards ; the yy Fig. 55. Fig. 56, HUMAN ARM-BONES; FRONT VIEW, 1, Shaft of ulna; 2, Greater sigmoid ” notch; 3, Lesser sigmoid notch; 4 Ole- RIGHT HUMAN HUMERUS ; ANTERIOR SURFACE, 1, Shaft; 2, Head; 3, Neck; 4, Greater tuberosity; 5, Lesser tuberosity ; 6, Bici- pital groove; 7, Interior bicipital groove; 8, Posterior bicipital ridge ; 9, Rough sur- face for insertion of deltoid; 10, Nutrient foramen; 11, Eminentia capitata; 12, Trochlea; 13,°External condyle; 14, In- ternal condyle; 15, External condyloid ridge; 16, Internal condyloid ridge; 17, Fossa for the coronoid process of ulna. cranon process; 5, Coronoid process; 6, Nutrient foramen; 7, Ridges for inser- tion of interosseous membrane; 8, talum ulne; 9, Styloid process; 10, Shaft of radius; 11, Its head; 12, Its neck; 13, Its tuberosity; 14, Oblique line; 15, Lower end of bone; 16, Styloid process, bicipital groove is single, and looks outwards. The inferior articular surface resembles that of animals, except that the condyle is more distinct. C. Forr-arm.— late by their extremities; they are se e two bones of the fore-arm, as we have already seen, onl from one another in their rida The superior extremity of the radius corresponds to the condyle of the humerus; . e 5 that of the ulna articulates with the humeral trochlea. The coronoid process belongs to the ulna. At the lower extremity of the fore-arm it is remarked: 1, That the radius ecor- responds to the ter portion of the carpus, while the ulna only articulates with the yramidalis ; 2, That the radio-carpal articulation is protected outwardly and inwardly y two small osseous prolongations, the styloid processes of the ulna and radius, D. Haxv.—1. Carpus.—The carpus of Man is composed of eight bones—four in each THE POSTERIOR LIMBS 91 . The three first of the upper row articulate with the radius; the fourth responds tothe ulna. In the bones of the lower row, the trapezium responds to the metacarpal of the thumb and that of the index; the trapezoides to the latter only, the os magnum ‘and unciform to the metacarpals of the medius, annularis, and little ss The pisiform bone and the cuneiform process of the unciform convert the posterior of the _ carpus into a channel. ~eS .—The five metacarpals of Man are parallel to each other, and articulate by their superior extremities with the bones of the car- 3 pus; by their inferior extremities with the phalanges. Fig. 57. y are all concave in their middle portion, and at their ends. The metacarpal of the thumb _ is the shortest and strongest. The others diminish in yolume from the fourth to tive first. 3. tal Region.—Here we find five digits, eath %.. of three bony columnettes, with the exception of thumb, in whic. only the second and third pha- langes are present. They decrease in length from the third to the first, and the third to the fifth. The first and second phalanges are small semicylindrical bones, slightly thickened at their extremities. The ungueal are constricted in their middle, and widened a horse-shoe at their inferior extremity ; the palmar fuce is roughened, the dorsal face smooth. Articts V.—Posterior Limss. a Each of these is divided, as already noted, “” into four secondary regions: the pelvis, thigh, leg, and foot. PELVIS. The pelvis is a kind of bony cavity formed PALMAR SURFACE OF LEFT the union of the sacrum with two lateral HAMAD ‘BAND. ; ‘ : +,, 1, Scaphoid bone; 2, Semilunare; pieces, the cox, which are consolidated with "3, Cuneiform; 4, Pisiform ; 5, each other in the inferior median line. The Trapezium ; 6, Groove in tra- description of the sacrum having been already pezium Biko tendon of flexor : ; } i radialis; 7, T es _ given, it now remains to speak of the coxa, 8, Ma en =a . 5, boda “3 : ta 1 bones ; A. Coxa, 11° 11, First row pret The coxa, also designated os iliacum, os inno- Mg: Peoned row; 13, 13, minatum, is a very irregularly-shaped flat bone, nd row; 14, First phalanx double (with its fellow on the opposite side), *,' pellescy 1S, Conrad and and directed obliquely from above to below and . before to behind. It is contracted in its middle part, which presents exter- nally an articular cavity, the cotyloid ; anteriorly, where it rests on the sacrum, it becomes widened, as it also does in its posterior portion, which a inflected cereece to be united, on the median line, with the bone of Py opposite ide. __ Itis divided, in the fotus, into three distt=t pieces, joined by cartilage ‘in the centre of the cotyloid cavity, which the three concur in forming. Although they soon become consolidated into a single piece, it is custo to describe them as so many separate bones by the names of ilium, pubis, and ___ Ierwm.—The ilium, a flat and triangular bone, curved on itself, directed obliquely from above to below, before to behind, and/within outwards, forms the anterior portion of the coxa which corresponds with the sacrum. . It is the most considerable of the three divisions, and has two faces, three borders, and three angles. 92 THE BONES. Faces.—The external or superior face, studded with some muscular imprints, is excavated on both sides, and is named the external iliae fosssa, — The internal or inferior face offers for study: 1, An external portion, — smooth, and crossed by some vascular grooves; this is the iliac surface, which is replaced in Man by an excavation called the internal iliae fossa; 2, An internal portion, roughened and uneven, presents, posteriorly, the auricular facet, an irregular diarthrodial surface, elongated from side to — side, a little oblique in front and inwards, and responding to an analogous — surface on the sacrum. F Borders.—The anterior border, or crest of the ilium, is slightly concave, Fig. 58, THE COX2; SEEN FROM BELOW. 1, Iliac surface; 2, Auricular facet; 3, Angle or crest of the ilium; 4, Angle of the haunch; 5, Cotyloid cavity; 6, Its bottom; 7, One of the imprints for the insertion of the anterior straight muscle of the thigh (rectus femoris) ; 8, Ilio-pectineal ridge; 9, Channel on the external face of the pubes; 10, Oval (or obturator) foramen ; 11, Ischial spine; 12, 12, Ischial arch. and bears a roughened lip for muscular insertion. The external border is thick, concave, and furrowed by vascular fissures ; it presents, inferiorly, the nutrient foramen. The internal border is thin and concave, particularly in its posterior part, which constitutes the great ischiatic notch. Angles.—The external angle, or anterior and superior spinous process, is thick, wide, and flat, and bears four tuberosities: two superior and two inferior. The internal angle, or posterior and superior spinous process, represents a rugged tuberosity curved backwards and upwards! The (' At the external angle of the ilium, there is sometimes found in the horse a process— often a very marked one—directed downwards, and completely enveloped by the external ilio-femoral muscle.) r d a : : THE POSTERIOR LIMBS. 93 posterior or cotyloid angle is prismatic and very voluminous. It exhibits : 1, Behind, a wide concave articular facet, which forms part of the cotyloid cavity; 2, Above this cavity, the supracotyloid crest, represented in Man by the ischiatic spine. This is an eminence elongated from before to behind, sharp on its summit, smooth inwardly, roughened outwardly, and continuous by its anterior extremity with the internal border of the bone ; 8, Outwardly, two deep imprints for the insertion of the rectus muscle; 4, In front and inwards, the ilio-pectineal eminence, a small elongated pro- minence forming the most salient point of a kind of ridge (linea Nom that insensibly subsides above on the inner face of the ilium, and is continu below by the anterior border of the pubis. _ Of the three angles of the ilium, the first is also termed the angle of the haunch, and the second the angle of the croup. Puxis.—Situated between the ilium and ischium, elongated from side to Fig. 59. PELVIS; FRONT VIEW. 1, Crest and anterior spinous process of the ilium; 2, Angle of the croup, with the auricular facets proceeding from it; 3, Shaft of the ilium, with the ilio-pectineal erest ; 4, Cotyloid cavity ; 5, Symphysis pubis; 6, Ischiatic tuberosity. side, flattened above and below, and irregularly triangular, the pubis, the smallest of the three divisions, is divided for convenience of description into two faces, three borders, and three angles. Faces.—The superior, smooth and concave, concurs in forming the floor of the pelvis. It shows one or two nutrient foramina. The inferior is roughened, and marked throughout its length by a wide channel which reaches the bottom of the cotyloid cavity. This fissure lodges the pubio- femoral ligament and a very large vein. Borders.—The anterior is constituted by a thin rugged lip, which is curved upwards. The posterior, thick and concave, circumscribes anteriorly a wide opening, the oval, subpubic, or obturator foramen ; it is channeled near the cotyloid angle by a fissure which runs obliquely inwards and down- wards. The internal is united with that of the opposite pubis to form the _ pubic portion of the pelvic symphysis. 4 THE BONES. Angles.—The external, also named the cotyloid angle, is the thickest of the three. To it chiefly belongs the rugged depressed surface that constitutes the bottom of the cotyloid cavity. The internal unites with the analogous — angle of the opposite pubis. The posterior is consolidated at an early period — ba the antero-internal angle of the ischium, to inclose, inwardly, the oval oramen. Iscu1um.—This is the mean, in volume, of the three pieces of the coxa. — Situated behind the pubis and ilium, it is flattened above and below, and of a ee form. It offers for study: two faces, four borders, and four — angles. . Faces.—The superior is smooth and nearly plane, and forms part of the floor of the pelyic cavity. It has a small nutritious foramen directed out- wards. The inferior presents some rugosities clustered particularly about the symphysis. i PELVIS; LATERAL VIEW. 1, Crest of the ilium; 2, Angle of the croup; 3, Shaft of the ilium; 4, Cotyloid cavity, or acetabulum; 6, Ischial spine. Borders.—The anterior, thick and concave, circumscribes the oval foramen posteriorly. The posterior, straight and directed obliquely forwards and inwards, forms, with the analogous border of the opposite bone, a large notch named the ischiatic arch. It exhibits, throughout its extent, a rugged depressed lip (the spine), arising from the side of the inferior face. The ea- ternal, thick and concave, constitutes the lesser ischiatic notch. The internal is joined to the ischium of the other side to constitute a portion of the pelvie symphysis. ; } '” Angles—The antero-external or cotyloidean is the most voluminous of the four, and affords for study: 1, An excavated diarthrodial facet, making part of the cotyloid cavity; 2, The posterior extremity of the super-cotyloidean crest, limited by a small transverse fissure which separates it from the external border of the bone. The antero-internal angle is consolidated with the posterior angle of the pubis. The postero-external angle forms the ischiatic tuberosity. This is a large prismatic process which looks upwards, and is prolonged by a salient ridge, elongated from before to behind, with its sharp border turned outwards and downwards. The postero-internal angle = a a ee we ee Ti ore THE POSTERIOR LIMBS, 95 forms, with that of the other ischium, the summit of the triangular space which constitutes the ischiatic arch, or pubic arch of some species. Tae Coxa iv Generat.—The bone whose three constituent parts we have just been studying, presents for consideration, as a whole, a middle portion and two extremities. The middle, very much contracted, offers, outwards and downwards, the cotyloid cavity (or acetabulum), which has not yet been described, because its study does not properly pertain to either of the three regions of the coxa. This cavity is intended to receive the articulating head of the femur, and represents the segment of a hollow sphere; it is circum- scribed by a very salient rim which is thin at its free margin and widely notched on the inner side. The deeper portion is occupied by the rough- ened and depressed surface already designated as the bottom of the cotyloid cavity (fundus acetabuli), and which communicates by the internal notch of the rim with the inferior groove of the pubis. The anterior extremity, flattened on both sides, and formed by the ilium, rests, as has been shown, on the sacrum. The posterior extremity, flattened in an inverse sense to the preceding, is constituted by the pubis and the ischium, and traversed, from above to below, by the sub-pubic (or obturator) foramen, the large oval aperture which separates these two bones from one another, and perforates the floor of the pelvis; this opening is closed in the fresh state by muscles. The two cox, by uniting in their posterior part, form the articulation to which has been given the name of ischio-pubic or pelvic symphysis ; thus united, the two bones represent something like a V with the opening in front; a circumstance which makes the lateral diameter of the pelvis greater in front than behind. SrructurE AND DrveLopment or THE Coxa.—To the three centres of ossification which constitute the coxa, are added two complementary centres: one for the anterior spinous process and spine of the ilium, another for the ischiatic tuberosity. In youth, the different parts of the coxa are very thick, and the spongy tissue is abundant, while the compact is rare. The pubis is always convex on its two faces, and the middle part of the coxa-—that adjoining the cotyloid cavity—is of considerable thickness, a feature which much diminishes the extent of the pelvic reservoir. As the animal advances in age, however, the layers of compact tissue increase in thickness, approaching each other as the spongy substance is lessened. The pubis becomes thinnest, and at an advanced period of life is sometimes even translucid. The compact tissue is always abundant in the neighbourhood of the cotyloid cavity, as this is the centre on which converge all the impulsive communicated to the trunk by the posterior limbs, It is also in this cayity that ossification commences. B. The Pelvis in General. 1, Exrernat anv Internat Conrormation tp. THE Petvis.—The pelvis is a kind of rear cavity in the form of a cone, which prolongs the abdominal cavity. It occupies the posterior part of the trunk, and with regard to its conformation, presents for study an external and an internal surface. External surface.—This may be resolved into four regions or faces. The superior region is slightly oblique from above to below, and before to behind; its degree of obliquity varies. It is contracted from before to behind, and shows: 1, On the median line, the spinous processes of the_ sacral and the first coceygeal vertebre ; 2, On each side the sacral grooves, at the bottom of which open the supersacral canals. 96 THE BONES. The inferior region is ay eee Formed by the pubes and ischia, it presents from before to behind: 1, In the middle, the ischio-pubie mphysis; 2, On each side the subpubie groove, the oval foramina, and the inferior face of the ischia ; 3, Quite externally, the cotyloid cavities, by which the pelvis rests on the posterior limbs. The /ateral regions are oblique from above to below and within to without, and wider in front than behind. They exhibit: 1, The spine of the ilium and the two anterior spinous processes; 2, The external iliac fossa ; 3, The ischiatic arch; 4, The supercotyloid crest or ischiatic spine, which presents outwardly the surface of insertion for the internal or gluteus muscles; 5, The lesser ischiatic notch ; 6, The ischiatic tuberosity. Internal surface.—The internal surface of the Horse’s pelvis cannot be divided into two portions as in Man, because the inner aspect of the iliac bones is not hollowed out to form an anterior cavity. The pelvis of Solipeds is, therefore, a simple conoid cavity, in which are dis- tinguished four regions or faces, and two apertures called the inlet and outlet. The anterior opening or inlet is nearly circular, especially in the Mare, and a little oblique downwards and backwards. It is limited above by the inferior face of the base of the sacrum; inferiorly, by the anterior border of | the pubis ; and on the sides by a portion of the inner face of the iliac bones, and also the internal aspect of the pectineal crests. The inlet presents four diameters: a vertical, horizontal, and two oblique. The first extends from the inferior face of the sacrum to the anterior border of the pubic symphysis; its mean length is 8+ inches. The second is measured from one pectineal crest or eminence to another ; the mean of this is 8,5; inches. The two last diameters are estimated from the inferior face of the sacro-iliac articulation of one side to the ilio-pectineal __ eminence of the other ; this is on an average 8,4, inches. These measurements irrefutably demonstrate that the inlet is not elliptical in the vertical direction. The posterior aperture or outlet, situated at the posterior end of the pelvic cavity, gives exit to the rectum and genital organs. As the pelvis of the horse is horizontal, the outlet should be considered as limited, we think, by the inferior face of the summit of the sacrum, the superior face of the ischia, the supercotyloid crest or ischiatic spine, and the internal face of the sacro-ischiatic ligaments. At the outlet only two diameters are recognised : a vertical and a horizontal. The vertical measures on an average 6,%, inches ; it extends from the inferior face of the sacrum to the superior face of the ischial symphysis. The horizontal diameter, comprised between the two supercotyloid crests, is 7,4, inches. The superior region of the pelvic cavity is a little concave from before to behind; it has for base the sacrum, which presents on each side of the median line the subsacral foramina, This part is also called the sacral plane or roof of the pelvis. The inferior region, or ischio-pubic plane, is formed by the pubis and the ischia. It is concave from side to side; its anterior border is nearly straight, and its posterior border is scooped out by a wide notch to form the arch of the ischium, It has been remarked by M. Gobaux, that the portion of this plane corre- sponding to the pubis presents numerous varieties. The superior face of the pubis may be convex in its anterior moiety and concave in its posterior; or it may be concave before and convex behind, the concavity being separated from the convexity by a transverse ridge, This ridge-is sometimes represented by a series of small conical eminences; at other times this upper face is eee a ae ee eC ”t—~—~— THE POSTERIOR LIMBS. 97 i as a smooth inclined plane, directed backwards and upwards, and _ a kind of rim surmounts the anterior contour of the oval foramen. With regard to the lateral regions, they are formed by a small portion* of the inner face of the ilia, and in great part by the sacro-sciatic ligaments. 2. Dirrerences In THE Pe.vis or THE Sxxes.—The pelvis of the Mare exceeds that of the Horse in all its dimensions, but the difference is most marked in thetransverse diameters. The anterior inlet forms a vast circumference when compared with that of the male ; the pectineal crests are widely apart, and the distance separating the anterior border of the pubis from the lower face of the sacrum is considerable. If the pelvis be viewed in its superior plane, it is found that in the Mare the ischiatic notches are very deep; that the internal border of the ilium forms a regularly curved and very concave line ; and that the supracoty- loid crests, or ischiatic spines, are widely separated from each other. It is also noticed that the floor of the pelvis is wide, and that the bones com- posing it tend towards the same horizontal plane. In the male, the ischiatic border is only represented by a very curved line; this line is composed of two almost straight portions, which join at an obtuse angle at the origin of the neck of the ilium ; the supracotyloid erests are relatively near each other, and bent towards the longitudinal axis ; while the two moieties of the pelvic floor are directed very obliquely down- wards and inwards. : In the Mare, the ischial arch is larger than in the male, and forms a regular curve uniting the two tuberosities of the same name. In the Horse, the two ischiatic tuberositics are but little apart from each other, and the ischial arch forms a somewhat acute angle whose borders are nearly straight. Lastly, when the pelvis is examined in its inferior plane, in addition to the features already indicated in the ischiatic arch, it is found that in the Mare the obturator foramina are large and nearly circular, while in the Horse they are elliptical ; the cotyloid cavities are also further removed from the ischio-pubic symphysis in the female than the male. ‘The sacrum of the Mare has appeared to us, in some individuals, to be a little more arched from before to behind than that of the Horse; but this character is not constant. The following figures relating to the capacity of the pelvis in the Mare and Horse confirm what has just been enunciated. MARE. HORSE. Horizontal Diameters. Horizontal Diameters, | Between the Pectineal | Between the Supercoty- | Between the Pectineal | Between the Supercoty- Crests. | loid Crests. _ Crests. | loid Coen Inches. Inches. Inches. Inches. 9} 7 Bk 6 ———— ee : ae MARE. HORSE, Vertical Diameters. Vertical Diameters, Between the Sacrum and Between the Sacrum and Between the Sacrum and | Between the Sacrum and Pubis, Ischium. | Pubis. Ischium. Inches Inches. Inches. Inches. 84 6%; 8 6) ~~. 98 THE BONES. To recapitulate, there is observed in the pelvis of the Mare: A great increase in the transverse diameters ; . A deep and regularly concave ischiatic notch ; A wide and concave ischial arch ; . Circular obturator foramina ; . The cotyloid cavities distant from the pubic symphysis. or ee oo BO THIGH, This has for its base one bone, the femur. Femur. The femur is a long, pair bone, situated in an oblique direction down- wards and forwards, between the coxa and the principal bone of the leg; it is divided into a body and two extremities. Body.—It is irregularly cylindrical, and presents for study four faces. The external, internal, and anterior, confounded with one another, are regularly rounded and almost smooth, showing only some slight imprints and vascular grooves, The posterior, nearly plane, and wider aboye than below, offers: 1, Outwardly and towards the superior third, an uneven circular surface ; 2, On the same level, and inwardly, a slight crest, oblique downwards and outwards; 3, In the middle, a very extensive roughened surface, having the form of an obliquely angular parallelogram, for the attachment of the great adductor muscle of the thigh; 4, Below this surface, a large vascular groove running obliquely outwards and downwards. On the limit of the posterior and external faces are found, towards the upper third, a large rugged, flattened eminence, curved in front, and termed the subtrochanterian crest,’ because of its position under the trochanter ; below, a deep fossa, named the subcondyloid, garnished at its bottom with asperities and bordered in front by an uneven lip. On the limit of the posterior and internal face, there is observed from above to below: 1, The small trochanter, a large scabrous tuberosity, elongated in conformity with the bone, and situated near its upper fourth; 2, A marked longitudinal imprint for the attachment of the pectineus ; behind, it is confounded with the surface for the insertion of the great adductor muscle of the thigh, and presents, in front, the nutrient foramen of the bone; 3, The origin of the great posterior fissure ; 4, Quite below, a collection of large tubercles which form the supracondyloid crest. Extremities —The superior extremity is sensibly flattened before and behind, and shows: 1, Inwardly, an articular head which is received into the cavity of the acetabulum. This head is separated from the other portion of the body by a neck, which is, however, not well marked in the Horse, and forms two-thirds of a sphere, excavated in its internal part by a very deep cavity for ligamentous insertion ; 2, Outwardly, a very large eminence, the trochanter, or great (external) trochanter, in which is recognised, as in the trochlea of the humerus: a summit, much more elevated than the articular head and slightly bent inwards; a convewity, incrusted with cartilage and anterior to the summit, from which it is separated by a narrow and deep notch; a crest situated under the convexity, and formed by a tuberculous surface on which one of the tendons of the middle gluteus muscle becomes ? This is the third trochanter of Cuvier, and takes the place of the external and superior branch of the linea aspera of Man. (It is the external smull trochanter of Percivall and the middle trochanter of Leyh.) _— - ee Le Sa THE POSTERIOR LIMBS. 99 inserted, after gliding over the convexity; 3, Posteriorly, the fossa of the trochanter, or digital fossa, a deep cavity studded with imprints and circumscribed, outwardly, by a salient lip which descends vertically from the summit of the trochanter to the posterior face of the bone, where it gradually subsides. _ The inferior extremity is flattened on both sides ; consequently, its larger axis crosses at a right angle that of the upper extremity. It is distinguished Fig. 61. Fig. 62. LEFT FEMUR; ANTERIOR VIEW. 1, Head; 2, 2, Trochanter major, with -its crest; 3, Trochanter minor externus, sub- trochanterian crest, or third trochanter; 4, Lesser, or internal trochanter; 5, Notch for insertion of ligamentum teres; 7, 8, LEFT FEMUR; POSTERIOR VIEW. 1, Head; 2, Great trochanter; 3, Third, or trochanter minor externus; 4, Lesser, or internal trochanter; 5, Fossa for insertion of ligamentum teres; 6, Trochanterian fossa; 7, 8, Tuberosities; 9, Fossa for the Tuberosities for tendinous and ligamentous insertion; 9, Trochlea. insertion of the external meniscus; 10, Supracondyloid fossa; 11, Condyles. by the presence of two condyles and a trochlea. The two condyles, placed one beside, the other behind, correspond to the superior extremity of the tibia. are separated by a deep depression designated the intercondyloid fossa, which lodges the spine of the tibia and the interosseous ligaments of the femoro-tibial articulation. The external condyle bears outwardly two fossm ; one superior, for ligamentous insertion; the other, inferior, for muscular H 2 100 THE BONES. attachment. The internal condyle presents, posteriorly and inwardly, near the posterior extremity of the intercondyloid notch, a roughened depression for the insertion of the fibro-cartilaginous meniscus interposed between the external condyle and the corresponding articular plane of the tibia. It is surmounted outwardly, i.e, on the side opposite to the intercondyloid notch, by a large tubercle of insertion. The frochlea, a wide pulley on which the patella glides, is situated in front of the condyles. It is slightly oblique downwards and inwards, and appears to continue in front the inter- condyloid notch. Of the two lips which border its cavity laterally, the internal is the thickest and the most prominent, Between the external and the corresponding con- dyle is seen a digital fossa for muscular insertion. Structure and development.—The femur, very spongy at its extremities, is developed from four principal centres of ossification: one for the body, another for the articular head, the third for trochanter, and the last for the inferior extremity alone. Fig. 63. LEG peroneus (or fibula), and the rotula (or patella). 1. Tibia. The tibia is a long, prismatic bone, thicker at the superior than the opposite extremity, and constituting the principal portion of the leg. Body.—This offers for study three faces and three borders. The faces are wider above than section or Lert remur, below. The external is almost smooth, and is SHOWING ITs sTRUCTURE. Concave in its superior part and convex below, where it deviates to become the anterior. The internal, slightly convex on both sides, presents? superiorly, deep imprints for the attachment of the adductor muscles of the thigh and the semi- tendinosus. The posterior, nearly plane, is divided into two trian surfaces: one, superior, slightly roughened, serves for the attachment of the popliteus muscle; the other, inferior, much more extensive, is furrowed into numerous longitudinal crests which give attachment to the perforans muscle. On the limit of these two surfaces is remarked the nutrient foramen of the bone. The borders are distinguished as anterior, eaternal, and internal. The first is rounded, and not very salient in its inferior two-thirds; it forms in its superior third, a curved crest, with the concavity external, which joins the anterior and superior tuberosity of the bone; this has received the name of the tibial crest. The external border is very thick and concave above, where it constitutes, in common with the fibula, the tibial arch. The internal is also very thick, straight, and provided superiorly with some salient tubercles to which the popliteus is attached. Extremities.—The superior extremity, the most voluminous, is formed by three tuberosities, an anterior and two lateral, which are external and internal. The first, the smallest, is a rugged process continuous with the tibial crest, and separated from the external tuberosity by a wide and This has for its base three bones: the tibia, situated between the femur and the astragalus, _ in an oblique diréction downwards and backwards, THE POSTERIOR LIMBS. 101 deep groove in which passes a tendinous cord; it is excavated, in front, by a vertically elongated fossa which lodges the middle ligament of the patella. The external jelarceih y, medium in size and the most detached, has outwardly an articular facet for the head of the fibula. The internal tuberosity, the largest ‘and least detached, presents: on the sides, ligamentous imprints ; behind, a small tubercle which gives attachment to the pos- terior crucial ligament of the femoro-tibial articu- lation. The superior face of the two lateral tube- rosities is occupied by two large irregular and undulated articular surfaces, which respond to the condyles of the femur through the medium of the two meniscus-shaped fibro-cartilages interposed be- tween the two bones. Of these two surfaces the external is always the widest, because it serves, by its posterior part, for the gliding movements of the popliteal tendon. ‘They are separated from each other by the tibial spine, a conical articular eminence divided into two lateral parts by a groove of inser- tion excayated at its base, and in front by two lateral facets for the insertion, anteriorly, of the two inter- articular cartilages; it is bordered behind by another fossa which receives the posterior insertion of the internal meniscus. The inferior extremity, flattened behind and before, exhibits an articular surface moulded on the pulley of the astragalus, and two lateral tuberosities. The articular surface is formed by two deep cavities oblique from behind to before and within outwards, and separated by a median tenon which terminates pos- teriorly by a very prominent projection on which the bone rests when it is made to stand vertically on a horizontal plane. he external tuberosity! projects but little, and is traversed in its middle by a vertical ooh internal tuberosity,’ better defined, is in steriorly by an oblique channel. O arasiers and detlopmont.—'The tibia is very compact in its inferior portion, and is developed from four chief centres of ossification. ‘The body is formed by one and the superior extremity by two, the anterior tuberosity taking one of these; the last develops the whole of the inferior extremity. It is rare to see the external tuberosity of this extremity formed from a separate nucleus. 2. Fibula (or Peronéis). A small, undeveloped bone, elongated and sty- Toid in shape, situated outside the tibia, and extend- ing from the superior extremity of that bone to the middle or lower third of its body. The middle portion of the fibula is thin and cylin- Fig. 64. POSTERIOR VIEW OF RIGHT TIBIA, 1, Tibial spine; 2, Fossa for the insertion of the internal meniscus; 3, External tuberosity with articulation for the fib- ula; 4, Fossa for the insertion of external meniscus; 5, Fibula, forming with the tibia the tibial arch; 6, Shaft, or body of the tibia; 7, 8, External and in- ternal malleoli, inferior tuberosities, or lateral processes of the tibia; 9, Articular trochlex with a median ridge, for articulation with the astragalus. drical, and forms above, in common with the external border of the larger ' The external malleolus of Man. 2 The internal malleolus. 102 THE BONES. bone, the tibial arch. Its superior extremity, wide and flattened on both sides, has received the name of head; it offers, on its internal face, a diarthrodial facet to articulate with the external and superior tuberosity — of the tibia; on its external face it shows ligamentous imprints. The — inferior extremity of the fibula terminates in a blunt point, and gives — attachment to the ligamentous fibres that unite it to the tibia. The fibula is sometimes continued to the external inferior tuberosity of the latter bone, with which it is confounded; and as it is particularly under such circumstances that this tuberosity has been noticed to be deve- loped from a special nucleus, it seems quite natural, having regard to the disposition observed in pachyderms and carnivores, to consider it as the inferior extremity of the fibula joined to the tibia. With these animals, indeed, the tuberosity or external malleolus is formed by the inferior ex- tremity of the fibula. Structure and development.—This bone is very compact, and developed from a single nucleus of ossification. 3. Patella. A small, short, and very compact bone, situated in front of the femoral trochlea, and annexed to the tibia, to which it is attached by three extremely solid ligamentous bands. The small polyhedron which it represents only offers for observation three faces: the superior, roughened, and serving for the insertion of the triceps cruralis and rectus muscles; the anterior, convex and irregular; and the third, the posterior, moulded on the femoral trochlea, to which it is but imperfectly adapted. In the fresh state, however, the articular surface formed by the latter face is completed by a fibro-cartilaginous apparatus, which will be noticed when describing the femoro-tibial articulation. This articular surface is composed: 1, Of a median ridge, which occupies the bottom of the trochlear cavity ;, 2, Of two depressed, gliding, lateral facets on the sides of this cavity ; the internal facet is always larger than the — external, a disposition which permits the patella of one limb to be distin- guished from that of the other. POSTERIOR FOOT. This region, which bears the greatest resemblance to the same region in the anterior limb, comprises three subdivisions: the tarsus, metatarsus, and the digital region. 1. Bones of the Tarsus. These are short, very compact bones, six or seven in number, and situated between the inferior extremity of the tibia and the superior extremity of the metatarsal bones; they are arranged, like the bones of the carpus, in two tiers—a superior and an inferior. Z The superior row only comprises two bones, the largest; these are the astragalus and the calcaneus (or caleis). The inferior row is formed, out- --wardly, by the cuboides alone; inwardly and anteriorly, it is subdivided into two secondary rows, the superior of which is constituted by the scaphoides, and the inferior by the large and small cuneiform bones. The last is sometimes divided into two, in which case there are three cuneiforms ; then the total number of the bones is seven. Astragalus—An irregular cubical bone, situated in front of the a —— — | THE POSTERIOR LIMBS. ealcanens, between the tibia and the scaphoid, and divided into five faces :— Fig. 65. LEFT HIND FOOT; EXTERNAL ASPECT. 1, Tibia ; 2, Summit of calcis or cal- caneus; 3, Astragalus; 4, Cuboid ; 5, Scaphoid; 6, Cuneiform mag- num; 7, Large metatarsal bone; 8, Small metatarsal bone; 9, Suf- fraginis, proximal, or first phalanx ; 10, Sesamoid bones; 11, Coronary, second, or middle phalanx ; 12, Pedal bone, or third or distal tea 14, Navicular bone; 15, T process of pedal bone. ~ 103 1, A superior and anterior, formed as an articular pulley to correspond to the in- ferior extremity of the tibia; this pulley, oblique from above downwards, forwards, and outwards, may be considered as the type of the most perfect trochlea in the organism; its groove receives the median tenon of ‘the tibia, and its two ridges or lips fit into the lateral furrows of that bone. 2, An inferior face, occupied by a slightly convex articular surface responding to the scaphoid ; this surface is notched outwardly by an excavation for ligamentous insertion. 3, A posterior face, irregular, cut into three or four diarthrodial facets adapted for similar facets on the calcaneus, and which are separated by a wide, rugged excavation. 4, An external face, covered with imprints. 5, An internal face, provided below with a small tubercle of insertion. Calcaneus.—A bone vertically elongated, flattened on both sides, and presenting (wo faces, two borders, and two extremities. The external “face i is smooth and nearly plane. The internal face is excavated into a gliding groove to form the tarsal arch, in which passes the tendon of the perforans. The anterior border is slightly concave. The posterior border is thicker, straight, and rugged. ‘The superior extremity, slightly tuberous, constitutes the summit of the caleaneus, and is divided into three parts: a middle, which gives attachment to the tendon of the gastrocnemius ;* the other, the anterior, is a smooth surface on which this tendon rests when the foot is much flexed ; the third, altogether posterior, also constitutes a gliding surface for the tendon of the perforatus. The inferior extremity, wide and voluminous, shows in front three or four articular facets which correspond to the astragalus, and are separated, like those of the last bone, by an irregular and slightly. excavated surface of insertion. Below, it shows for articulation with the cuboid a fifth facet, continuous with one of the preceding. Development.—The calcaneus is deve- loped from two nuclei of ossification, one of which is for the summit. Cuboid bone.—This little bone, situated at the external side of the seaphoid and the 104 THE BONES. large cuneiform Lone, between the caleaneus and two of the metatarsals, does not resemble a cube, but a parellelopiped elongated from before to behind. — It offers six faces: a superior, an articular face, and in contact with the calcaneus ; an inferior, also articular, responding to the principal and external rudimentary metatarsal bones; an internal, furnished with three facets for contact with the scaphoid and great cuneiform, and crossed from before to behind by a fissure, which forms with these two bones a vascular canal ; an external, an anterior, and a posterior, covered with imprints. Scaphoid bone (the large cuneiform of Percivall).—Flattened above and - below, it is described as having two faces and a circwmference. The faces, both articular, are furrowed by a channel of insertion, and are distingui as superior and inferior. The first is concave, and responds to the astra- galus; the second is convex and in contact with the two cuneiform bones. The circumference offers, outwardly, two small facets which are adapted to similar facets on the cuboid bone. For the remainder of its extent, it is covered with imprints. Great Cuneiform bone (the middle cuneiform of Percivall).—Flattened above and below, and triangular in shape, this bone is much smaller than the scaphoid, though resembling it in a striking manner. Its superior face — is in contact with the latter bone, and its inferior face articulates with the middle and internal lateral metatarsal bones. Its external border is provided with one or two facets to correspond with the cuboid bone; and its internal border also offers one, which is in contact with another on the small cuneiform. Its anterior border is roughened throughout its extent. Fig. 66. Fig. 67. LEFT HOCK; FRONT VIEW. LEFT HOCK; INTERNAL ASPECT, 1, Apex of calcaneus; 2, Astragalus, inner 1, Apex of calcaneus; 2, Inner articular ridge; 3, Scaphoid; 4, Cuneiform mag- ridge of astragalus; 3, Navicular, seaphoid, num; 5, Cuboides. or cuneiform medium; 4, Cuneiform mag- num; 5, Cuboides; 6, Cuneiform parvum, Small Cuneiform bone.—Situated at the inner side of the tarsus, this bone, the smallest of any yet examined, is elongated from before to behind, flattened on both sides, and wedged in between the os scaphoides, the large cuneiform bone, and the large and internal small rudimentary metatarsal bones, with which it corresponds by four articular facets: a superior, two inferior, aud one internal. When this bone is in two portions, there are then three euneiforms, which may be distinguished, as in Man, by naming them first, second, and third. —.- =" Te, OF i | THE POSTERIOR LIMBs. 2. Bones of the Metatarsus. 105 These bones are three in number, a median and two lateral, and offer the analogy to the metacarpal bones. bones in the anterior limb. The princi an behind, is nearly a regular cylinder. It presents out- a fissure which is directed at first obliquely wardly _ backwards and downwards, and afterwards descends vertically along the lateral external metatarsal bone. The articular surface of the superior extremity is ex- cavated in its centre by a large fossa of insertion. The inferior extremity is at the same time wider and thicker than that of the metacarpus. Of the two rudimentary (digital) or lateral metatarsal bones, the external is always longest and thickest. The internal bears on the superior face of its head three articular facets, two of which respond to the small cuneiform, and the third to the large bone of that name. 3. Bones of the Digital Region. The digital region of the posterior closely resembles that of the anterior limb. The analogy in the con- formation of these bones is even pushed so far, that it becomes very difficult to distinguish them from one another. It is remarked, nevertheless: 1, That the first pha- lanx is not so long as in the anterior limb, and less wide and thick at its inferior extremity, but is, on the con , wider and thicker at its superior extremity ; 2, That lateral diameter of the second phalanx is shorter; 3, That the third phalanx, less spread out towards its inferior border, has more the shape of a V, and that its inferior face is more concave; 4, That the sesamoids are less voluminous; 5, That the navicular bone is shorter and narrower. DIFFERENTIAL CHARACTERS OF THE POSTERIOR LIMB IN OTHER THAN SOLIPED ANIMALS, A. Peuvis,—It is remarked: 1, That in all the domesticated animals, with the exception of Solipeds, the direction of the coxs is nearly horizontal; 2, That in ail, except Solipeds, the ilium tends to assume a vertical direction; 3, That in all the trans- verse diameter of the pelvis is relatively less extensive. In the Oz, Sheep, and Goat, the space betwen the two coxm is scarcely so great in front as behind; the ilium is not volumi- nous, and has only three processes on the superexternal iliac > There is no furrow on the lower face of the pubis, and upper face, like that of the ischium, is very concave. pendent bone, and described by them as the interischial bone.) This enables us to dispense with general description of them, and to confine ourselves only to indicating the differential characters which distinguish them from the corresponding l, or median metatarsal bone, is longer than the same its body, instead of being slightly compressed before and Fig. 68. POSTERIOR ASPECT OF LEFT METATARSUS. 1, Head of principal metatarsal bone; 2, 3, External and in- ternal splint bones, or metatarsals of the rudimentary digits ; 4, Rough surface for insertion of suspen- sory ligament; 5, Nutrient foramen; 6, Middle ridge of inferior articular surface. Three eminences are seen on n early life, the ischio-pubie symphysis shows an epiplysary nucleus in the middle of its inferior face. of the ischium has been considered by some anatomists as an inde- (The epiphysis on 106 THE BONES. The rim of the cotyloid cavity has also three notches, and the supracotyloid crest, or ischiatic spine, is very elevated and sharp, and but little roughened outwardly. The extern] iliac fossa of the Sheep and Goat is separated into two portions by a small longitudinal crest. The pelvis of the Pig closely resembles that of the smaller ruminants; though the crest = the ilium is convex, and there is no protuberance outside the ischio-pubie symphysis. In Carnivora the lateral diameter of the pelvis is greater behind tlianin front. The ilium is nearly vertical, and its external face is much depressed. The notch forming the ischial arch occupies no more than the internal moiety of the posterior border of the ischium ; between this arch and the ischiatic tuberosity is a rugged lip directed down- wards. There is no furrow on the lower face of the pubis. ; B. Tuicu.—In all the domesticated animals except Solipeds, the femur tends to become curved, prismatic, and triangular ; the rior face contracts, and the surfaces of insertion that it presents gradually approach each other until they become confounded and form the linea aspera in certain species, The head is more distinct; the small trochanter is a rough tubercle, and is joined to the large trochanter by an oblique osseous lip; the latter trochanter subsides and forms a single mass whose summit and convexity are con- se the third trochanter, the fossa, and the supracondyloid crest are more or less effaced, In the Ox, there is no subtrochanterian crest; the supracondyloid fossa is shallow, and the cre:t little noticeable. ‘The head is well detached and lias its centre ex- cavated by a shallow fossa of insertion. The trocllea is narrow, and its inner border ascends much higher on the anterior face of the bone than the external. In the Sheep and Goat, the general form of the femur resembles that of the Ox. It is observed, however, that the body is slightly curved backwards; that the supracondyloid fossa is nearly obliterated ; that the trochanter has subsided nearly to a level with the articular head, and that the trochlea is circumscribed by two equal-sized lips. In the femur of the Pig there is also noticed a supracondyloid fossa, but it is wide and shallow; the rugosities of tle posterior face are replaced by some salient lines; the trochanter is on a level with the head; the latter is supported by a somewhat constricted — neck, and is situated within and in front of the great trochanter. This latter disposition changes the direction of the great axis of the superior extremity, which obliquely crosses that of the inferior extremity. In the Dog and Cat, the femur is long and curved like a bow. The rugged surfaces of the posterior face are confounded, and form two crests representing the linea aspera of the human femur. These crests do not lie against each other in the middle portion of the bone; they are merely parallel, then they diverge above and below, to terminate beneath the great and small trochanters, and above the two condyles. The great tro- chanter is not so high as the articular head. The femur of Carnivora is also distin- guished: 1, By the complete absence of the third trochanter and the supracondyloid fossa—this last being replaced by a small tubercle which terminates below the external branch of the linea aspera; 2, By the marked constriction and length of the neck sup- porting the articular head; 3, By the _ of the digital fossa, which is bordered by an oblique lip extending from the great to the small trochanter. C. Lec.—In the leg-bone there is observed, in the various domesticated animals, differ- ences analogous to those mentioned as existing in the fore-arm of the thoracic limb. More particularly is this the case with regard to the development of the fibula; in Ruminants this bone is reduced to its inferior nucleus. In these animals the patella is alsv very narrow; and in all the domesticated species except Solipeds, the articular grooves in the lower end of the tibia are directed immediately from before to behind. In the Ox, the tibia is short ; it is longer in the Goat and the Sheep. Thie tibia of these animals is remarkable for: 1, The absence of the lateral facet on the supero- external tuberosity; 2, The absence of a vertical fossa on the anterior tuberosity; 8, The absence of roughened lines on the posterior face; the obliquity downwards and inwards of the inferior articular surface. The most salient point of this surface is the anterior extremity of the middle tenon. The body of the fibula and its upper extremity are replaced by a fibrous cord which is sometimes ossified wholly or in part. # In the Pig, the fibula is flattened on both sides, extends the whole length of the leg, and is united to the tibia by its two extremities ; above, by a diarthrodial facet; below, by an intervsseous ligament. It is developed from three ossifie centres; the inferior articulates with the calcaneus and astragalus, and forms a prominence resembling the — external malleolus. ; In Carnivora, the tibia is long and slender, and presents a salient anterior crest. The THE POSTERIOR LIMBS. 107 ibula is also as long as the tibia, and is united to that bone at three points: at the two nities by articular surfaces, in the inferior third and middle by an interosseous ___D. Posrerior Foor.—1. Bones of the tarsus—The number of tarsal bones varies a little in the domesticated animals, as the following list will show : «Chit ReOmIneOUa hig. ek a ee Ox, Sheep, and'Goat.; 2. kw se ST ma. In the Dog, Cat, and Pig, there are three cuneiform bones, and in the Oz and Sheep, i on to there being only two cuneiforms, the scaphoid and cuboid bones are con- solidated into one piece. _ ‘The astragalus of the carnivora articulates with the scaphoid by means of a veritable head ted from the rest of the bone by a constriction termed the neck of the astra- galt cuboid and the cuneiform bones respond to all the metatarsals. In the Pig, the astragalus and calcaneus are very long. The cuneiforms and cuboid to the four perfect digits. tarsus of the domesticated Ruminants is slender above. The astragalus is elongated _ from above to below, and is united to the scaphoid by an antero-posterior groove, and to _ the caleaneus by a more superficial vertical groove. The calcaneus is long and tiiin; eee posters gliding surface on the summit is excavated into a channel; the small is pisiform and but slightly developed. 2. Bones of the metatarsys.—The metatarsus is also a region in which the number of bones varies the domesticated animals. Thus in the Carnivora and Pig there are five, and only two in Ruminants. The s of the Carnivora and Pig are exactly like the same bones in the anterior limb. Those of Ruminants are slightly different. ‘ In the Dog and Cat are one rudimentary and four perfect metatarsals. The former is articulated with the internal cuneiform, and represents tle vestige of the thumb. The “iy boag four perfect metatarsals, and an internal rudimentary one. The latter is a small flattened on both sides, articulating by means of a diarthrodial facet, and some consolidated behind the upper end of the fourth metatarsal. __ In the Oz, Sheep, and Goat, is found a Ss a a rudimentary metatarsal bone. , sneer latter is like oa rudime “rane age ; e Bigy > gowpicey from ie x se ne in being longer, q ilateral in form, an ving a vasc _ canal traversing the posterior face of its upper extremity. ___-8. Bones of the digital region —In all the domesticated animals, the posterior digits comport themselves exactly like the anterior. The Carnivora alone offer a notable differ- ence; in them, in reality, the thumb does not exist; or rather, it is only represented by rudimen metatarsal bone alluded to above. Nevertheless, it frequently occurs a com y developed thumb is found in this animal; and in this case the rudi- mentary metetarsal is ordinarily followed by a ligamentous cord, to which is suspended a stylet that represents either the inferior extremity of the metatarsal, or the first ; it is to this stylet that are found articulated in succession the second and third (Professor Fuchs, of Carlsruhe, found, in a Newfoundland dog, four true claws and _ two false; the internal of the latter corresponded to a well-developed, small metatarsal _ bone, while the external was only rudimentary, terminating in a point, and bound to the _ tarsus by a simple ligament.) —_ COMPARISON OF THE ABDOMINAL LIMB OF MAN WITH THAT OF ANIMALS. ? A, hea longitudinal axis of the pelvis of Man forms, with the horizon, an about 40°. e of “ere bones which compose it are proportionately larger and stronger than in all the domesticated animals. ' _ _ The two faces of the ilium, and especially the inner face, are much hollowed ; the _ iliac crest has the form of an italic S. _ The pubis alone participates in the formation of the pelvic symphysis, and the con- , eerhty whic in the domeSticated animals, ig called the ischial arch, is designated in Man ‘ é XY consequence of the excavation on the inner face of the ilium, the pelvic cavity : age Sviced into the great and lesser pelvis. In the latter are lodged the genital P urinary organs, as well as the extremity of the digestive tube. B. Tuicu.—The femur of Man is nearly vertical, and situated in a direction slightly 108 THE BONES. oblique downwards and inwards; it presents a curvature forwards. The body of the bone is prismatic and triangular in its middle part; the posterior border of tris prism forms a somewhat salient crest, which takes the place of the insertion eminences on the pos- terior aspect of the femur in animals, and is designated the linea aspera. This bifurcates above and below; below, the branches margin a triangular or popliteal space. HUMAN PELVIS; FEMALE. 1, Last lumbar vertebra; 2, 2, Intervertebral substance; 3, Promontory of the sacrum; 4, Anterior surface of the sacrum; 5, Coccyx; 6, Iliac fosse ; 7, Antero- superior spinous process; 8, Antero-inferior spinous process; 9, Acetabulum,— a, Its notch; b, Body of ischium; ¢, Its tuberosity; d, Its spine; e, Pubis; f, Be Symphysis pubis; g, Arch of the pubes; , Angle of os pubis; i, Spine of pubes, with crest between it and h; 4, 4, Pectineal line; /,/, llio-pectineal line, with its prolongation, m, mj; n, Ilio-pectineal eminence; 0, Smooth surface for femoral vessels; p, p, Great sacro-ischiatic notch. The head is supported by a long neck, inserted obliquely into the superior extremity. ae two condyles are joined together in front by the trochlea, which is wide and allow. C. Lzc.—Three bones: the tibia, fibula, and patella. The tibia is very long ; its crest (or spinous process) is much more developed than in any of the domesticated animals, and describes a kind of curve like an italie S. On the inner aspect of the inferior extremity is seen a voluminous process which occupies, inwardly, a portion of the tibio-tarsal articulation: this is the internal malleolus. The articular surface oe not exactly formed to correspond with the whcle articular surface of the astragalus. The fibula is as long as the tibia. It is prismatic, and slightly twisted on itself. It articulates above and below with the tibia, ‘lhe lower extremity responds to the astra- yalus, and forms a prominence named the external malleolus. There is nothing particular to note in the patella. D, Foor.—The foot of Man is situated in a horizontal direction. Its upper aspect is convex ; its inferior face is excavated, and it rests on the ground by its two extremities, 1. Tarsus.—In the tarsus there are seven bones, three of which are cuneiform The astragalus articulates with the tibia and fibula; it responds to the scaphoid by a well detached convex articular surface, named the head, In the bones of the lower row, it is remarked that the cuboid responds to the fifth and fourth metatarsals; the first cuneiform to the third; the second cunciform to the second metatarsal, and the third to the first. 2. Metatarsus.—The metatarsus is composed of five bony columns, nearly parallel to each other, They are enumerated from without to within, and increase in length from the first to the fourth; the fifth is the shortest and most voluminous, ’ ee ee [= ae THE LIMBS IN GENERAL, 109 8. Digital region.—This comprises five digits or toes. The phalanges of these toes are analogous cl of the fingers, from which they are distinguished by their small size. They increase in volume from the first to the fifth digit. Fig. 70. Fig. 71. Fig. 72. HUMAN TIBIA AND FIB- DORSAL SURFACE OF LEFT ULA OF RIGHT LEG; HUMAN FOOT, 5 gis apse ASPECT. 1, Astragalus; 2, Its An- 1, Shaft of tibia; 2, Inner terior extremity articu- intertrochanteric line; 6, Lesser trochanter ; 7, External condyle ; 8, In- ternal condyle; 9, Tu- berosity for attachment of external lateral liga- ment; 10, Fossa for ten- don of origin of popliteus muscle; 11, Tuberosity for attachment of in- ternal lateral ligament. tuberosity; 3, Outer tuberosity; 4,,Spinous process; 5, Tubercle; 6, Internal surface of shaft; 7, Lower extremity of tibia; 8, Internal mal- leolus; 9, Shaft of fib- ula; 10, Its upper ex- tremity; 11, Its lower extremity; between 1 and 6 is the sharp crest of the tibia. lating with the cuboid bone, 4; 3, 3, Calcis; 4, Scaphoid; 5, Inter- nal cuneiform bone; 6, Middle cuneiform bone ; 7, External cuneiform bone; 8, Cuboid bone; 9, Metatarsal bones of first and second toes; 10, First phalanx of great toe; 11, Second ditto; 12, 13, 14, Pha- langes of second toe. _ Anricre VI.—Tue Lies in Generar AND THEIR PARALLELISM. A. Te Lowes iy Generat.—The interrupted columns which compose the limbs are destined not only to support the trunk in a stationary attitude, but also to transport it during progression. This double destination gives rise toa difference between the anterior and posterior members. The front limbs, 110 THE BONES, — being nearer the centre of gravity than those behind, have to sustain the largest share of the weight. They ought, consequently, to be specially organised as organs of support. Therefore it is that the four principal rays — composing each of them—shoulder, arm, fore-arm, and foot—although flexed, — or disposed to be flexed, in an inverse sense to one another, oppose to the pressure of the weight of the trunk, which tends incessantly to throw them down, obstacles purely mechanical, and of such energy that we may still understand how the body can be sustained on the anterior limbs, if we suppose all the muscular masses surrounding these bony rays removed except one. Thus, the weight of the body is at first transmitted to the scapula the muscles that attach that bone to the trunk. It then passes to humerus, and from thence to the radius, to be thrown, finally, on the different pieces composing the foot. Now the humerus forming with the scapula an angle which is open behind, and with the bones of the fore-arm another angle open in front, the weight of the body pressing continually on these angles tends to close them, and thus cause the flexion of the bony rays. But this result is prevented by the combined action of two muscular powers—the biceps and the extensors of the fore-arm. With regard to the radius, carpus, and metacarpus, owing to their vertical direction they themselves support the pressure of the weight of the-body without requiring any muscular aid. But the digital region, being directed obliquely forward and downward, forms, with the principal metacarpal, a third angle open in front, for the sustenance of which nature has given solid, inert, or contractile mechanical bands. : The anterior limbs are also agents of transport, for they can elevate the trunk by the spring of their bony rays, and fix themselves on the ground by their free extremity. ) The posterior limbs are less favourably disposed than those in front to — assume the function of columns of support, as their rays are for the most part in a state of permanent flexion, and joined in an angular manner to one another, as may be seen by glancing at the skeleton ( Figs. 1, 2, 3, 4, 5). It is therefore necessary that muscular agency should prevent the breaking-down of these rays. Though defective as supporting columns, they are nevertheless admirably designed to serve as agents of locomotion. The slightest erection of these inclined rays propels the mass of the body forward, and this impulsion is almost wholly transmitted to the trunk in consequence of the very intimate union of the pelvis with the vertebral column. B. PARALLEL BETWEEN THE ANTERIOR AND Posterior Lies,—After what has just been said, it will be seen that the anterior limbs are more par- ticularly destined for the support of the body, while the posterior ones more especially play the part of impulsive agents in the locomotory acts. Notwithstanding this difference in the functions assigned them, these two columns offer in their conformation such striking resemblances to each other, that some authors have been inclined to consider the posterior as an exact repetition of the anterior limb. The following is a brief analysis of the analogies existing between them. . At the end of the last century, Winslow and Vicq-d’Azyr, and nearer our own time, Cuvier, Flourens, Paul Gervais, Martins, Gegenbaur, and Lavocat, have occupied themselves with the parallelism existing between the anterior and the posterior members. All these anatomists did not absolutely arrive at the same conclusion; for several of them, forgetting that the question should be examined in the whole animal series, made Man alone the subject of their THE LIMBS IN GENERAL. 111 _ meditations. In such a matter, it must not be forgotten that the limbs are constructed with a view to their physiological functions, and that the differences remarked in examining them in several species are dictated by _the kind of life the animals are intended to lead. ____ Vieq-d’Azyr and Cuvier recommend that the anterior and posterior limbs _ of opposite sides should be compared. Martins and Gegenbaur, allowing a torsion of the humerus of 180°, advise that the two members of the same side should be collated, care being taken to make allowance for the untwisting of the 180° contortion at the lower end of the humerus. ‘Lastly, Flourens and Lavocat contrast the two members of the same pair with each other, after placing the hand in a position of natural pronation by _ rotation of the radius on the ulna, and without turning either limb or ray, or even a portion of a ray, no matter what kind of animal may be under examination. We will adopt the latter proceeding, as it is the simplest and most natural. Parallel between the coxa and scapula.—The analogies existing between these two bones are but little striking at first sight ; nevertheless, with atten- tion there is no difficulty in finding in the coxa the three pieces that enter into the composition of the shoulder. The ilium represents the scapula. The external iliac fossa reminds one of the supra- and subspinous fosse. Occasionally, there is met with in the Horse a rudiment of the crest dividing the iliac fossa into two parts, and, in some animals—the Pig, Sheep, and Goat—this crest, which is the trace _ of the scapular spine, becomes constant and very evident. With regard to the cotyloid cavity, it repeats in the posterior limb the id cavity of the scapula. There remains to determine in the latter the portions analogous to the ischium and pubis. If we rely upon the evidence afforded by the muscular insertions, we come to the conclusion that the ischium corresponds to the coracoid process, and the pubis to the clavicle _ of animals which are provided with one. It will also be remarked that the coxa is directed backwards, while the scapula inclines obliquely forwards; this opposition in the direction of the bones in no way alters their analogies ; _ the functions of the members to which they correspond require this inverse ition. a Parallel between the femur and humerus.x—The resemblance between these two bones is remarkable. Th*s there is found in the first: 1, An _ articular head, better detached than that of the humerus, but shaped in the same manner; 2, A trochanter analogous to the great tuberosity, and. also like it decomposable into three distinct parts—summit, crest, and convexity ; 8, A lesser trochanter, representing the smaller tuberosity ; 4, An eminence for the insertion of the superficial gluteus muscle, which takes the place of _ the deltoid imprint; 5, An inferior articular pulley continued between the two condyles by a non-articular groove; this trochlea certainly corresponds | to the median groove of the inferior humeral face. _ There are, no doubt, differences between the two bones, but they have no bearing upon the result just indicatel. Thus the linea aspera of the femur is situated behind; that of the humerus in front. In the femur the two condyles of the inferior extremity are placed behind the trochlea ; the contrary holds in the humerus. These modifications are necessary in order to give the movements of the limbs a convenient direction. The leg is ' flexed backward on the thigh, while the fore-arm is flexed in front on the Parallel Letween the bones of the leg and those of the fore-arm—It is 112 THE BONES. has: appeared less complicated had it been studied in a large number of are It has been pretended that the patella and the upper part of the tibia represent the superior extremity of the ulna and radius; and that the inferior portion of the ulna is represented by the fibula, and the lower part __ of the radius by that of the tibia. This opinion is erroneous. Itistrue that in Man the tibia and patella articulate with the femur, as the superior extremity of the ulna and radius responds to the humerus. But in quad- rupeds, whose thoracic members are destined to sustain the weight of the body, this disposition is no longer observed; the radius is seen to give support to all the humeral surface, just as the tibia receives the femoral surface; and, besides, the ulna becomes only a simple complement to the — elbow articulation, as the fibula does to the femoro-tibial articulation. The tibia, therefore, corresponds to the radius, and the fibula to the ulna. The olecranon is represented by the superior nucleus of the fibula, and not by the patella. The latter bone is nothing more than a kind of sesamoid, — intended to facilitate the action of the extensor muscles of the leg. It might be objected to this comparison that, in the anterior limb, the extensor muscles are attached to the olecranon. But we reply that it matters little where the muscles which move the leg or arm are fixed on one or other of the two bones of these regions, because these bones act conjointly in the movements of flexion and extension. Parallel between the bones of the posterior and those of the anterior foot.— The analogy becomes so marked when these two regions are compared, that it is scarcely necessary to allude to it. The tarsal bones are to the posterior limb what the carpals are to the anterior one; it is even possible tocompare, __ one by one, the several pieces in these regions. The metatarsals are but a — repetition of the metacarpals ; while the digital bones are so much alike that it is difficult to distinguish the anterior from the posterior phalanges. more particularly in these two‘regions that the question of i . been resolved in: a contradictory manner by anatomists. It w have: — #7 a-*- AF a CHAPTER III. THE BONES IN BIRDS. Tuese animals, destined for the most part to sustain themselves in the air, should exhibit in the conformation of their skeleton all the conditions which may favour zerial locomotion; fiom this arise the differences which distinguish their skeleton from that of mammalia,— differences which will now be rapidly traced. Verresrai. Cotumn.—Cervical vertebra.—The cervical stalk represents in the bird, as in the mammal, a kind of balancing pole curved like an 8, which supports the head, and by its changes of form and direction varies the centre of gravity. When a bird rises in the air and flies rapidly, it lengthens the neck and stretches out the head to carry the centre of gravity forwaids. But when it rests on the ground, it makes the balancing-pole assume the natural «nd more or less giaceful inflection, by throwing the head backwards, and transferring the greater portion of the weight of its body to the columns of support formed by the posterior members. These displacements of the centre of gravity are executed in birds on a more extensive scale than in mammalia; the vertebral stalk in the former is also longer, lighter, and enjoys an excessive mobility. The vertebre composing it number fourteen in fowls, twelve in the pigeon, fifteen in j the duck, and eighteen in the goose; in the swan twenty-three have been counted :—a curious variety which singularly contrasts with the numerical unity noticed as one of the most remarkable characters in mammalia! These vertebre are generally longer than in the latter class, and are particularly distinguished by the configuration of the THE BONES IN BIRDS. 113 _ ‘articular surfaces of the inferior part or body. These are diarthrodial facets convex in _ one sense and concave in the other, articulating the vertebral bodies by a veritable and Fig. 73. SKELETON OF A FOWL. From a to B, Cervical Vertebre.—1, Spinous process of the third vertebra ; 2, Inferior ridge on body of the same; 3, Styloid prolongation of the transverse process of I id THE BONES. ‘ replaced by a facet concave from one side to the other, and convex vertically; whilethe _ posterior extremity of the bone bears, instead of a concavity, a facet convex in the lateral oe fy The atlas has no transverse processes, This vertebra is shaped like a thin ring, and is excavated on its anterior contour by a small cavity into which is received the single condyle of the occipital bone. The axis shows a very marked odontoid process with a single facet under that eminence, Dorsal vertebrx (Fig. 73. B, C.).—These are seven in the Fowl and Pigeon, and nine in the Goose and Duck ; they are nearly always consolidated into a single piece to which the trunk is fixed, and which gives the wings a solid support in the violent efforts that flight demands. The two or three last are often even covered by the wing-bones, and joined to them. The inferior crest of the body forms a very long spine, especially in the first vertebre. Tne spinous processes, flat, wide, short, and consolidated with each other by their opposite borders, constitute a long crest extending from the last cervical vertebia to the bones of the wings (fig. 73, 7). ‘Tue transverse processes widen to their summit; in the fowl they are nearly constantly fused with each other. Lumbar and sacral vertebre.—All these vertebre are formed exactly on the same type; so that it becomes difficult, if not impossible, to fix the point where the lumbar region ends or the sacral begins. At first independent of each other, these vertebra, numbering fourteen, soon become consolidated with one another and with the ribs; but their primitive separation is always indicated by the lateral septa which form, on their inferior face, the vestiges of the transverse processes. The former are closely united to the latter in the dorsal region. ~ eal vertebrx.—In the coecygeal region, the spine recovers its mobility. The tail of the bird, indeed, fulfils the office of a rudder to direct it during flight; and it is absolutely necessary that the vertebree which serve as a base fur the steering feathers should preserve their independence, so as to allow these to be carried to the riglit, left, downwards, or upwards. ‘These vertebra, seven in number, present spinous processes which are often bifurcated, transverse processes very developed, and sometimes even spines more or less long on the inferior surface of their bodies, The last vertebra is always the most voluminous; it is flattened on both sides, and terminates in a curved-up 2 int. Heap (Fig. 73, F. G.).— The head of the bird is small, and of a conical form. The anterior extremity is elongated, and terminated by a pointed or flattened beak, which allows the animal to cut the air with more facility. the same; 4, Vertebral foramen of the same; 1’, 2’, 3’, 4’, The same parts in the twelfth vertebra.—From B to ©, Dorsal Vertebra.—6, Spinous process of the first ; 7, Crest formed by the union of the other spinous processes. —From D to E, Coccy- geal Vertebra.—F, G, Head.—8, Interorbital septum; 9, Foramen of communica- tion between the two orbits; 10, Premaxillary bone; 10’, External openings of the nose; 11, Maxilla; 12, Square bone; 13, Jugal bone.—n, Sternum.—14, Brisket or keel; 15, Episternal process; 16, Internal lateral process; 17, Lateral external process; 18, Membrane which closes the internal notch; 19, Membrane of tne external notch.—t, etc., Superior Ribs.—20, Posterior process of the fiftn.—s, Inferior ribs; K, Scapula; L, Coracoid bone; M, Furculum,—m, m, Its two branches.—N, Humerus; 0, Ulna.—o, Radius.—p, Pp’, Bones of carpus; Q, 9’, Bones of metacarpus; R, First phalanx of the large digit of the wing.—r, Second phalanx of the same.—r’, Phalanx of thumb; 8, Ilium; s’, Ischium; 8%, Pubis.—21, Sciatic foramen; 22, Foramen ovale.—tT, Femur; v, Patella; v, Tibia; x, Fibula.—y, Single bone of tarsus.—yY, Metatarsus,—23, Superior process representing a united metatarsal bone; 24, Process supporting the claw.— z, etc., Digits. THE BONES IN BIRDS. 115 Bones of the cranium—'The bones which compose the cranium are, a3 in mammalia, an occi yi ngs frontal, ethmoid, sphenoid, and two tempura!s. These bones are it ted from each other, excepting during early life in the shell; and the ossifying ress which unites them is so rapid, that the cranium, shortly after hatching, is aly asingle piece. No detailed description of the separate bones will be given here, ‘only a few brief observations which may be of some utility. __ Thus, the occipital bone shows for articulation with the spine only a single condyle, situated under the occipital furamen, and excavated by a slight groove. In palmipedes, this bone is pierced, behind the crests which give attachment to the extensor muscles, _ by two foramina which penctrate the cranium, and represent permanent fontanella. The jetal bone is fcebly developed, and formed from only two primary nuclei. The frontal is the largest bone of the cranium; its orbital process is supported a particular piece which is generally considered as belonging to the large wing of the sphenoid. The perpendicular lamina of the ethmoid is considerable, and ey o>... < forms between the two orbits a thin vertical septum (fig. 73, 8). Its posterior border is notched ite to the optic foramen, and thus constitutes an opening which com- municates between the two orbital cavities (fig. 73,9). It is also channeled, near its upper border, by a fissure which terminates by two openings ut its extremities, one _ entering the cranium, the other the nasal cavities. ‘This fissure and these foramina _ permit the passaye of tlie ethmoidal nerve, which in this way traverses t!e orbit before _ arriving at its destination. The ethmoidal cells are more membranous than buny ; their base is attached to a very delicate transverse plate, which is often membranous and not _ ¢eribbled, and forms yart of the anterior orbital wall. These cells replace, at the same time, the lateral masses of the ethmoid and turbinated bones of mammalia. The 1 nes appears to be formed of a single piece, and shows on its sides two diarthrodial 4 ts corresponding to the pteryguids. It is pierced by one foramen for the passage of _ the optic nerves; but this foramen opens on the outer and opposite side of the posterior _ netch of the interorbital septum, and thus allows each of the nerves passing through it _ to reach the eye for which i: was intended. It is worthy of remark, that an analogous disposition is also nuticed in the 1abbit.' The temporal bones present at their base an articular surface corresponding tu the square bene. In the fowl species, the zygomatic process forms a small flattened tongue, _ direct:d forwards, sometimes free, and at other times united by its superior border _ to the summit of the orbital process. These two eminences are exceedingly short in pigeons. In palmipedes they are consolidate | and confounded so intimately, that it 4 impossible to distinguish them from one wnother. From this union results a _ long and strong process, which inclines forward and meets a pxrticular prolongation of _ the os unguis, forming with it areal bony arch. This arch limits, below anJ outwardly, _ the orbital cavity. Bones of the face—The supermaxilla c mprises: a premaxilla, two nasal, two _ lachrymal, two te, two pteryguid, two zygomatic bones, and a vomer. The inferior _ jaw has for its base a maxillary bone, which articulates with the cranium by means of _ two supplementary pieces named the square bones. The premazillary bone is found, before hatching is completed, of two lateral pieces, which represent the two small premaxillaries of mammals. This bone is very considerabley*.od of itself forms the base of the 5 gaa beak, whos form it determines; it is pointed ad conical in the gallinacea, and wide and flattened above and below in palmipedes. In front it cireumscribes the external ings of the nose, and is prolonged superiorly into two lengthy processes which dovetail between the nasal bones. T'wo inferior processes belonging also to this | ‘bone concur in the formation of the palatine roof. Tue supermazillaries, analogues of the supermaxillaries of mammals, are two rudimentary bones situated on the sides und . _ at the base of the beak. ‘They form a part of the palatine roof and the wulls of the Basal cavities. Vhe nasal bones circumscribe above, inwardly, and even outwardly, the | external orifices of these cavities. The palate bones encircle, as in mammals, the guttural openings of the nose, and constitute in great purt the roof of the palate; their p-sterior extremity lies against the pterygcids; the auterior joins the supermexillaries and the prior process of the premaxillary bone. The pterygoids extend obliquely from the henoid to the square bones, and are united totlie sphenvid by diarthrodial articulation. + +! This analogy is nally striking, and might, in our opinion, serve as a basis for _ & new determination of the interorbital septum. We are tempted, indeed, to consider _ this bony lamina as the inferior sphenoid and the middle portion of the ethmoid of birds. This manner of viewing it na to confirm the ideas of M. Tabourin on the inferior _ sphenoid and the ethmoid of mammals. é .” I a yy Ms a] 116 _ THE BONES. _ ive aygomatic bones have the Sass of WR aay ee soe en uare “ bone by their posterior, and consolidated with ike sn illary by their =* extremity. ‘The vomer separates the guttural openin the nose from one another. am The bones of the upper jaw are not fused with each other so rapidly as the bones of the cranium. The ascending processes of the premaxillary and nasal bones even remain for a long time united to the frontal bone by a simple synarthrodial articulation. a4 w arrangement allows the br, Bek beak to execute a certain elevating movement, of we will speak when describing the articulations. The inferior mazillary bone is originally formed of a great number of distinet ments which are soon united into a solid piece. The square, petrous, or bone of tympanum ought to be considered as detached from the temporal. It is prismatic shape, and provided on its upper surface with a diarthrodial facet which unites it temporal, and on its lower face with another facet articulating with the branch maxilla. Outwards it joins the zygomatic bone, and inwards with the Behind, it gives attachment to the membrane of the tympanum; and in front it presents a small eminence of insertion which Meckel considered a second zygomatic 2s cist , hm. Se ee eee ee : process, THorax.—Sternum (fig. 73, H).—The sternum of birds serving as a basis of tio the muscles moving the wings, should offer, and does in fact show, a remarkable of strength, because of the extraordinary volume of these muscles. And these being more powerful and energetic as the bird exhibits a greater degree of aptitude for flight, it results that the structure of the sternum is solid in proportion as the bird is strong on the wi For this reason we may infallibly pronounce as to the extent and power of a bird’s by an inspection of the sternum of individuals of its species. In this respect, however, we only announce what is well known to be a particular application of the rules established <2 by the great law of concordance between the anatomical disposition of organs and their physiological finality. Studied in Palmipedes, which will serve as a type for description, the sternum presents itself in the form of a large rectangular cuirass, elongated from before to behind, of itself constituting the inferior wall of the thoracic cavity, and also largely protecting the abdominal cavity. Its superior face is concave, while the inferior is convex, and entirely occupied by the insertion of the pectoral muscles. It presents, on the median line, a thin and very salient ridge, named the brisket (or keel), which in a remarkable manner multiplies the points of atiachment of these muscles. The anterior border offers in its middle a small eminence of insertion, the episternal. Laterally, two articular grooves are seen which correspond to the coracoids. The posterior border is eut by two notches | which are often converted into foramina. On the lateral borders are o ed small “| double articular facets answering to the inferior ribs. The angles which separate these two borders from the anterior are both prolonged into a little eminence, named by some authors the costul process. In the Fowl, the sternum is not so strong as in the Goose or Duck. On each side of the brisket it shows two wide notches, which greatly reduce its substance. These notches, closed in the fresh state by membranes, are distinguished as external and internal. The latter, of greater size than the formér, extends nearly to the extremity of the bone. From this division of the lateral plates of the sternum result two and slender processes directed backwards. The external terminates by becoming wi and forming a kind of bony plate, which covers the last inferior ribs. The sternum of Pigeons is distinguished by the enormous development of the brisket. The two notches of the fowl are also met with in these birds, but the internal is nearly always converted into a narrow furamen. This comparative study of the sternum in the chief domesticated birds leads us to appreciate the correctness of the principles just evunciated, with regard to the form and extent this bone may exhibit. ‘The Gallinaceous Birds, properly so called, which fly little and badly, have the sternum singularly weakened by the deep notclies cut in its lateral parts. With Palmipedes, the sternum is wide and but slightly notched, so that the goose and duck, which waddle along so awkwardly in our poultry roe are capable of sustaining long and rapid flight, like that of the wild individuals of the same species. With regard to Pigeons, which are well known to be swift and powerful flyers, may this advantage not be due to the extraordinary development of the keel which constitutes the brisket ? Ribs.—In the Fowl and Pigeon there are seven pairs of ribs; and in the Duck nine pairs. Articulated superiorly with the dorsal vertebra, as in mammals, these bones are rovided near their middle with a flat eminence which commences at the posterior bet and is directed backwards and upwards to rest by its free extremity on the external face of the next rib. These eminences (Fig. 73, 20) form an epiphysis at an THE BONES IN BIRDS. 117 otic period, and are ustially absent in the first and last ribs. They concur in an manner to increase the solidity of the thorax. : costal cartilages in mammalia are in birds often transformed into veritable ribs, joined to the superior ribs by a diarthrodial articulation (Fig. 73, 1). These are long and strong, and all t-rminate at their lower extremity by a double set which articulates with the lateral border of the sternum; they are nearly always d in the two first ribs. It is not rare to see the last united to the one before it, of passing directly to the sternum; in which case it comports itself like the asternal ribs of the mammalia. _ _ Awrterton Mempers.—Shoulder-bone.—The shoulder comprises: a scapula; a par- ticular bone named the coracoid by Cuvier; and a clavicle, which forms, im coalescing __ with that of the opposite side, a single bone called the fork ( fureulum), or os furculare. , is narrow, elongated, and falciform, and shows no trace of a spine. Its extremity only forms a portion of the glenoid cavity, and is united by means of a! age with the fork of the coracoid bone. The latter is so named because it cbliguely the coracoid process of mammals, and is a long prismatic bone, directed ? * ia above downwards, and before to behind. Its superior extremity is often with the scapula, and united at an acute angle with that bone to form a portion of the articular cavity which receives the head of the humerus, Its inferior extremity is flattened from before to behind, and responds by a diarthrodial articulation to the anterior border of the sternum. The coracoid is long in birds which fly slowly ; it is, on the contrary, short, thick, and therefore very solid in quick flyers. The fork is a single bone, shaped like a V or U, situated at the base of the two wings, in front of the trunk, and in an oblique direction downwards and backwards. Tle two branches which form it represent the clavicles; they meet and are united at their inferior extremities, where they describe a curvilinear angle more or less open, attached to the brisket by means of a membranous li . Their superior extremity rests within, and opposite to the cavity, against the scapula and coracoid, forming with these bones a remarkable through which passes the tendon of the elevator muscle of the wing (Fig. 73, A, 4, B, 6). The fork plays the zens of an elastic spring, whose office it is to prevent the ngs coming to each other during contraction of the depressor muscles. The of this bone is, therefore, like the sternum, related to the extent and power of saa and for this reason it is that, in swift flyers, the two branches of the fureulum are solid, widely 7 rs ) mae Ak WHITE OR NON-ELASTIC FIBROUS YELLOW OR ELASTIC FIBROUS TISSUE, FROM TISSUE, . THE LIGAMENTUM NUCH, aspect of the articulations are termed peripheral, and those in their interior are designated interosseous or interarticular ligaments. The peripheral ligaments are generally composed of parallel fibres collected in fasciculi, or spread out as membranes. In the first they are called funicular, or ribbon-shaped ; in the second, they are termed mem- braniform, or capsular. The funicular ligaments constitute short, round, or flattened bands, attached by their extremities to the two bones they unite ; they are lined on their inner aspect by the synovial capsule, and covered externally by tendons, aponeuroses, muscles, veasels, or nerves. The 2: a gl igaments are often complete—that is to say, they envelope the whole articulation like a sack. At other times they are incomplete, and 126 TUE ARTICULATIONS. then they are simple membranes, binding together the different funicular bands of a joint. | The interosseous ligaments, less numerous than the preceding, are often formed of interlacing fibres; they are always funicular, and fixed by their extremities into excavations in the centre of articular surfaces. b. The yellow ligaments are all peripheral, funicular, or membranous, and enjoy a marked degree of elasticity, which permits them mechanically to bring back to their usual position the bony levers which have been momen- tarily displaced. These ligaments, which are powerful auxiliaries to the muscular forces, are destined to give equilibrium in a permanent- manner to the weight of certain parts of the body which incessantly tend to fall to the round, “ Synovrat Capsutes.—These are very thin membranes of a serous nature, intended to secrete the synovia, They are composed of two layers: a deep, formed by fasciculi of the connective tissue; the other, superficial, is of an epithelial character. The first sometimes adheres intimately to the inner face of the funicular or membranous ligaments of the articulation ; at other times it is loosely attached to them by an abundance of connective tissue. The second layer is constituted by a single row of flattened polygonal cells. It is generally admitted that the synovial membranes comport themselves like the other serous membranes, by forming sacs which are everywhere closed. According to this admission, a synovial membrane, after covering the internal face of the peripheral ligaments of a diarthrodial articulation, ought to be prolonged on the free surface of the cartilages of incrustation, and should give them their brilliancy and polish. But it is necessary to state that this is a pure hypothesis, against which rises a multitude of care- fully-observed facts. The discussion of these belongs to general anatomy, but they will be referred to here as briefly as possible. 1. If direct observation be consulted, it gives on this debated subject the most precise information; the cartilages are uncovered, and there is no synovial membrane on their face. The anatomists who have mistaken for this membrane the thin pellicle which it is possible to render evident on the cartilages in obliquely cutting their substance and separating morsels by tearing it off, were evidently deceived. This pellicle has nothing of a serous nature in its texture; it is not vascular, for it has never been possible to inject vessels on the surface of cartilages, nor yet in their thickness; it is not covered by epithelium; and submitted to microscopical examination, it exhibits all the characters of the amorphous matter of cartilage. It ought, then, to be considered as a cartilaginous pellicle, detached from the super- ficial layers of the articular surface—a pellicle which it has always been impossible to find on cartilages which are quite fresh; and it has never been possible to observe it without giving, by a preliminary desiccation, a certain degree of tenacity to the cartilaginous substance about to be examined. 2. Pathological facts prove nothing in favour of the existence of a synovial membrane on the cartilages. Hypertrophy of this pretended membrane has never been witnessed ; the fungosities looked upon asa result of this hypertrophy are derived from another source. It has been demonstrated that they extend. in certain cases, from the articular margins of the cartila- ginous surface, whence their successive invasions may often be followed. In other cases, the vegetating membrane which constitutes them appears in the centre of the articular surfaces, at points deprived of cartilage; they after- wards extend to a certain distance on the remaining cartilage. THE ARTICULATIONS IN GENERAL, 127 3. It may be asked of the partisans of the opinion now combated, how they can believe in the existence of a serous membrane between two articular surfaces, without its being exposed to bruises and destruction a thousand times in the day? Do they take into account the amount of sustained by certain articulations, and the intense friction to which ir surfaces are submitted? Have they compared the intensity of these destructive influences, with the delicate texture of the serous membranes, and their great inflammatory susceptibility ? It is sufficient to lightly touch in this way the weak side of our adversaries’ argument, and to conclude the third portion.of this discussion: There is friction between the cartilages of the two opposed articular surfaces, therefore there must be wear; this is os hmp law which no body escapes, let it be as hard as the diamond, or as as caoutchouc. And if there is wear between these rubbing surfaces, there cannot be an irritable and sensitive membrane lying on the inert and insensible strata which constitute them. In fine, a synovial membrane, after being fixed to the margin of the articular cartilage of a diarthrodial joint, is reflected in every direction to cover the inner aspect of the liga- ments, and becomes attached to the periphery of the diarthrodial surface corresponding to the first. There are generally found within articulations little masses of fat which push the synovial membrane enveloping them inwards. Erroneously con- sidered by Clopton Havers as glands for the secretion of synovia, these accumulations of fat have been named synovial fringes. They are more par- ticularly numerous in the neighbourhood of the articular margins: that is, on the edges of diarthrodial surfaces. ‘The synovia is a viscid, colourless, or slightly yellow fiuid, in its physical characters somewhat resembling oil; it does not possess them, however, so far as its composition is concerned, for chemical analysis has not demonstrated the presence of fatty principles. It is the albumen it contains which gives it its viscidity, and which fits it for lubricating the articular surfaces over which it is spread. Its use in the animal economy is absolutely identical with that of the greasy substances employed to lubricate the axles of carri ji Movements.—The movements peculiar to diarthrodial articulations are divided into seven principal classes : 1. Simple gliding, the only movement possible between two plane or undulating facets. 2. Flexion, which brings two bony pieces nearer each other by closing more or less their angle of union. 3. Extension, the inverse movement, during which the bones are straightened on each other. 4. Adduction, which brings the inferior extremity of the movable bone towards the median line. 5. Abduction, the contrary movement to the preceding. 6. Circumduction, or the sling movement, during which the bone passes successively through the last four positions. 7. Rotation, in which one bone pivots on another. CuassrricaTion or THE DrarntHroses.—The basis of this classification is founded on the configuration of the articular surfaces and the nature of the movements they permit. This double base serves to establish five kinds of diarthrodial articulation : 1. Enarthrosis, characterised by the reception of an articular head within 128 THE ARTICULATIONS. a cavity of appropriate form. This articulation may be the seat of the most extensive and varied movements: flexion, extension, abduction, adduction, circumduction, and rotation. Example: the coxo-femoral articulation. = 2. The trochlean, angular ginglymoid, or perfect hinge articulation, — when the articular surfaces are formed into trochlea, reciprocally fitting into each other, and whose movements—flexion and extension only—are executed with the precision of a hinge, Example: the tibio-tarsal ar- ticulation. 8. The condyloid, or imperfect hinge articulation, which permits, like the preceding, the two principal movements of extension and flexion, and the accessory movements of rotation or lateral inclination. The articular surfaces, though very diversely shaped, nevertheless exhibit in all the articulations one or more condyles opposed to an equal number of oyal excavations. Example: the femoro-tibial articulation. 4. The pivot, trochoid, or lateral ginglymoid articulation, is a diarthrosis formed by a pivot which turns in a semi-cylindrical cavity. Rotation is the only movement. Example: the atlo-axoid articulation. “4 5. Arthrodia, or planiform diarthrosis, is constituted by plane, or nearly plane facets. Gliding is the only possible movement. Example: the carpo- metacarpal articulation. Nomenciature.—The names of the articulations are usually those of the bones which form them. For instance, the scapulo-humeral articulation is the joint between the scapula and humerus ; the intervertebral articulations join to each other the various pieces constituting the spine. When the qualifying name of an articulation is composed of two elements, as in the ~ first instance, it is well to place first the word which indicates the bone usually most fixed. GENERAL CHARACTERS OF THE SYNARTHROSES. Sutures are the temporary articulations which exist only at an early period of life. They nearly all disappear in the adult animal, in con- sequence of the bones forming them becoming consolidated. They belong almost exclusively to the bones of the head. ArticuLar Surraces.—The bones forming these come in contact by their borders or angles, which, for this purpose, generally present very anfractuous surfaces. : Sometimes they are cut perpendicularly and simply roughened; at other times they are bevelled and joined by means of fine lamine or trifling inequalities; again, they are notched into deep and sinuous dentations ; and lastly, one bone is fixed into a groove cut in the other. It will be understood that such conformations of the articular surfaces ought to limit their movements and assure the solidity of their union. ; Movzs or Union.—Cartilage interposed between these synarthrodial surfaces directly unites them to each other. It absolutely possesses the same texture as the primary cartilage of the bones, and like it, has the property of becoming ossified after having been vascularised. This ossi- fication, which causes the disappearance of the sutures, occurs earlier inwards than outwards. The periosteum, in passing from one bone to another, adheres intimately to the sutural cartilage, and also aids in bringi about a more complete synarthroses. It should, therefore, be included in their means of union. Movements.—-These are very obscure, and only noticeable in young ARTICULATIONS OF MAMMALIA IN PARTICULAR. 129 animals by the clasticity they communicate to the bony walls of the cranium or face. In the adult, they may be said to be null. _ _ Otasstrication.—There are four principal descriptions of sutures : - 1. When two wide bones correspond by means of denticulations fitting into each other, the suture is named true or dentated. Example: the articulations uniting the three portions of the parictal bone. 2. If the borders of two bones in contact are widely bevelled, one inwards, other outwards, it forms a scaly or squamous suture. Example: the ieto-temporal articulations. 3. When the union of bones takes place or roughened surfaces, cut perpendicularly on their borders or es, this constitutes the harmonia suture, or suture by juxtaposition (or appo- _ sition). Example: the occipito-temporal articulations. 4. The schindylesis, or mortised suture, results from the reception of a bony plate into a groove more or less deep in another bone. Example: the spheno-frontal and supermaxillo-nasal articulations. GENERAL CHARACTERS OF THE AMPHIARTHROSES OR SYMPHYSES. Articutar Surraces.—They are frequently smooth, and formed almost on the same model as the diarthrodial surfaces. They are covered by a thin layer of cartilage, but instead of being smooth and polished, they are more or less rugged, without, however, presenting the anfractuous disposition of the majority of synarthrodial surfaces. Moprs or Unrton.—The organs which perform this office are: 1, The 4 i which establishes continuity between the articular surfaces ; 2, Ribbon-shaped or peripheral ligaments. These latter do not differ from the analogous bands attaching the diarthrodial articulations. With regard to the fibro-cartilage, it is distinguished from the complementary discs of these same articulations by a less intimate mixture of the cartilaginous and fibrous elements entering into its composition. The last may be sometimes absent, as well as the peripheral bands; and then the articulation only differs from the synarthroses by the extent of motion it permits Occasionally the interarticular fibro-cartilages are excavated by one or two little narrow cavities ; but these are never lined by a synovial membrane like the diarthrodial cavities. Movements.—The amphiarthroses only permit of a see-saw or swinging de seers the extent of which depends on the thickness of the intermediate ‘ Crasstrication.—Only one kind of amphiarthrosis is recognised, the most remarkable example of which is found in the articulations between the ‘bodies of the vertebre. CHAPTER II. ARTICULATIONS OF MAMMALIA IN PARTICULAR. Ty the special study of the articulations, the same order will be followed _ a8 for the bones; the articulations of the spine will be first noticed, then those of the head, thorax, and anterior and posterior limbs. Preparation.—The preparation of the bones which have been described has not been made the subject of any particular recommendation, because it suffices, in order to study them, to remove the soft parts by which they K 130 THE ARTICULATIONS. | Pel are surrounded either by boiling, maceration, or ——- But when we come to examine the soft textures, in order to do so profitably it is necessary to learn beforehand the rules which should be followed in their preparation. The following are laid down with regard to the study of the articulations: = 1. To prepare the articulations, young subjects are chosen in preference to those ad- vanced in years, because the density of the cellular tissue in them is not so great, and this — tissue is easily removed from around the ligaments. As these Soars difficulty when the external surface is in a dry state, care should be taken before dissecting them — to have them excluded from the air by covering them with damp cloths, or with the skin of the animal. : mS cf " ‘ > 2. It is convenient to separate the articulation we wish to dissect by sawing th 4 melpe Pepin. 5 the bones at a certain distance from the articular surfaces. The mani bet is then rendered easier, and its dissection can be made under the most favourable conditions. sting 3. It is necessary to preserve as carefully as possible the muscles popes a = articulations, in order to be able to study their relations with the ligaments which b ; these. If it be absolutely necessary to remove them, their insertions corresponding to the articulation should always be retained. Pee 4. The capsular ligaments should be the first studied, as these have soon to be removed the better to show the funicular ligaments. These, in their t must be sacrificed in order to display, by different sections, the interosseous cords, when these exist. Lastly, the two articular surfaces should be completely separated, so as to examine their conformation. ' . 5. The synovial membranes, with their different culs-de-sac, being a very important study, with reference to the diagnosis and treatment of articular tumours, it is convenient to devote a special piece to the examination of these serous membranes. It is ¥ useful to inject their interior with plaster or tallow coloured black, in order to sar mpeg and thus aid the study of their relations with ligaments, tendons, or muscles. , For the preparation of each articulation it is not necessary to ere any directions ; a glance at the figures accompanying the description will suffice to dispel any embarass- _ ment the student may experience, while he always requires particular indications, = (Notwithstanding the above remarks with regard to the preparation of the li ts, I have thought it advisable to follow the example given in the last edition of Sa Anatomy’ by Zundel, and briefly indicate the readiest method of demonstrating - organs, for the special benefit of the student.) Articte L—ARTICULATIONS OF THE SPINE. (Preparation.—Remove all the soft parts surrounding the vertebral column, taking care not to injure the inferior longitudinal ligament in cutting away the pillars of the diaphragm and the psoas muscles; nor the ligaments uniting the articular processes to each other and the transverse processes of the dorsal vertebra to the ribs, in senor nee supercostal and transverse spinal muscles. To expose the common superior longit ligament, separate the bodies of the vertebre from their annular portions by the saw or chisel, and remove the spinal cord and dura mater; in doing this the inferior face of the interannular ligaments will be also removed. Examine an intervertebral fibro-cartilage by two sections—a transverse at an equal distance from the two vertebra, and a longi- tudinal through the middle line of the bodies.) These articulations are intrinsic and extrinsic. The first comprises all the articulations of the vertebra with each other; the second those of the spine with the head, the ribs, and the coxe. Intervertebral Articulations. The vertebrae correspond: 1, By their bodies; 2, By their spinal or annular portion, ‘There results from this union two kinds of articulation, which must be studied separately, as they do not belong to the same class. It is well to mention, however, that the general details into which this study leads us apply only to the articulations uniting the last six ARTICULATIONS OF THE SPINE, 131 cervical vertebra, all the dorsal and lumbar vertebre, and the first sacral Union or Toe VerTEBrR# By THEIR Bopres.—The articulations forming this union are so many amphiarthroses. . Articular surfaces.—The vertebral bodies come into contact by the ‘surfaces which terminate them before and behind. In the cervical region these surfaces represent, anteriorly, a veritable head, posteriorly, a cotyloid _ eavity which receives the head of the next vertebra. Beginning from the first dorsal vertebra and passing on to the sacrum, these tend to become effaced and more and more plane, though they still preserve their convexity and concavity. Modes of union.—1, By fibro-cartilages interposed between the articular surfaces; 2, By a common superior vertebral ligament ; 3, By a common inferior vertebral ligament. a. Intervertebral fibro-cartilages (Fig. 80, 1, 1).—These are circular or elliptical discs, convex in front, concave behind, and solidly fixed by their faces to the articular planes which they separate. The fibro-cartilaginous substance composing them consists of concentric layers, which become denser and closer to each other as they near the circumference ; they even disappear towards the centre of the disc, where this substance becomes pulpy and assumes the histological characters of” pure cartilage. It may be remarked, that each of these layers is made up of a collection of thick parallel filaments, which cross with those of other layers like an X, and are attached by their extremities to the articular surfaces. From this arrangement results so inti- mate an adherence between the vertebral bodies and their intermediate fibro- i that an attempt to disunite them is more likely to determine a fracture of the former. The fibro-cartilages, thicker in the cervical and lumbar regions than in the dorsal, respond by their circumference to the two common ligaments. Those which separate the vertebre of the back concur to form the intervertebral cavities, which are destined for the reception of the heads of the ribs, and give attachment to the interosseous costo- vertebral ligaments. (Leyh designates the superficial fibres of the excentric layer of these i as intervertebral ligaments. Luschka has shown that the cartilages are in reality articular capsules.) b. Common superior vertebral ligament (Fig 83, 1).—This ligament extends from the axis to the sacrum, and is lodged in the spinal canal ; it ts a long fibrous band cut on its borders into wide festoons, (The wide portions correspond to the discs.) By its inferior face, it is attached to the intervertebral discs and the triangular imprints on the upper faces of the bodies of the vertebra. Its superior face is in contact with the dura mater through the medium of an abundant cellulo-adipose tissue. Its borders are margined by the intra- vertebral venous sinuses (vene basium vertebrarium). ¢. Common inferior vertebral ligament (Fig. 84, 5).— Situated under the spine, this ligament is absent in the cervical and the anterior third of thedorsal region. It only really begins about the sixth or eighth vertebra of the latter region, and is prolon m¢ in the form of a cord, at first narrow, then gradually widening until it reaches the sacrum, on the inferior surface of which it terminates by a decreasing expansion. From its commencement, it is attached to the inferior crest of the bodies of the vertebrm and the interver- tebral discs. By its inferior face, it responds to the posterior aorta. (Leyh commences this ligament at the seventh cervical vertebra, and says K 2 132 THE ARTICULATIONS, that it adheres to the crests on the bodies of the dorsal and lumbar vertebra, as well as to the lower face of the sacrum and coccyx. At the fifth dorsal vertebra it widens and thickens, and in the lumbar region is bound up with the pillars of the diaphragm and confounded on each side with the large ligaments of the pelvis.) Union oF THE VERTEBRH BY THEIR Spina Portions.—Each vertebra, in uniting by its annular portion with that which follows or precedes it, forms a double arthrodial joint. Articular surfaces.—These are the facets cut on the anterior or posterior articular processes, and which have been described when speaking of the vertebre themselves. They are covered by a thin layer of cartilage. Modes of wnion.—1, A common superspinous ligament; 2, Interspinous ligaments; 3, Interlamellar ligaments; 4, Ligamentous capsules, proper to the articular processes. a. Common superspinous ligament.—This ligament, whose name suf- ficiently indicates its situation, extends from the sacrum to the occipital bone and is divided into two portions: one posterior, or superspinous dorso-lumbar ligament; the other anterior, or superspinous cervical ligament. These two ligaments, although continuous with one another, yet differ so strikingly _ in form and structure that they are best described separately. 1, Superdorso-lumbar ligament (Fig. 80, 2).—This is a cord of white fibrous tissue, which commences behind on the sacral spine and ceases in front about the inferior third of the dorsal region by insensibly assuming the texture and elasticity of the cervical ligament, with which it is continuous. It is attached in its course to the summits of all the lumbar spinous processes and to the ten or twelve last dorsal. On the sacral spine, it is confounded with the superior ilio-sacral ligaments. In the lumbar region, it is united on each side to the aponeuroses of the common mass of muscles, 2. Superspinous cervical, or simply cervical ligament (Fig. 104, 1, 2).— This ligament is entirely formed of yellow fibrous tissue, and constitutes, in the median plane of the body, a very remarkable elastic apparatus which separates the superior cervical muscles of the right side from those of the left, and plays the part not entirely of an articular band, but rather of a permanent stay charged to balance the weight of the head. In the cervical ligament there is distinguished a funicular and a lamellar portion. The first, usually called the cord of the cervical ligament, is a wide funiculus which extends directly from the first dorsal spinous processes to the summit of the head. Divided into two lateral lips by a median groove, this cord is continued posteriorly with the dorso-lumbar ligament, and is inserted forwards into the cervical tuberosity of the occipital bone. It is covered above by a mass of fibro-adipose tissue which, in certain common- bred horses, is very abundant. Below, it gives rise, in its posterior two- thirds, to the majority of the fibres belonging to the lamellar portion, On the sides, it receives the insertions of several cervical muscles. The lamellar portion, comprised between the funicular portion, the spinous processes of the second dorsal vertebra, and the cervical stalk, constitutes a vast triangular and vertical septum, which itself results from the apposition of the two laminw which lie back to back, and are united by cellular tissue; they are bordered above by the two lateral lips of the cord. The elastic fibres which enter into their composition are given off either from the latter, or from the spinous processes of the second and third dorsal vertebra; they are directed downwards or forwards, and reach the spinous processes of the last six cervical vertebre, into which they are inserted by so many digitations, ARTICULATIONS OF THE SPINE. 133 becoming confounded with the interspinous ligaments of the neck. The fibres of the two last digitations are few in number, widely separated from one another, and united by many anastomosing branches, which make them appear as a kind of wide network. The lamine of the cervical ligament are in relation, outwardly, with the superior branch of the ilio-spinal ligament, the transverse spinous muscle of the neck, and the great complexus. _ (This important structure, which is in reality the mechanical stay and support of the heavy head and neck of quadrupeds, and is usually termed the i m nuche, is all but absent in Man, being represented in him by a thin narrow band, or rather two thin planes of fibres, the ligamenta subflava. It is described by Leyh as if there were not two portions, and that excellent anatomist does not appear to insist sufficiently on the difference between the dorso-nuchal and the dorso-lumbar divisions. Percivall, who almost entirely neglects the ligaments, also makes no distinction. The difference in structure, elasticity, and situation, warrants the distinction made by Chauveau. As already indicated, the function of this ligament, and more particularly of its nuchal division, is to maintain the head and neck in their natural position during repose, and to allow the most extensive movements at other times. b. Interspinous ligaments (Fig. 80, 3).—Fibrous lamine fill the inter- ‘spinous spaces, and are attached, before and behind, to the opposite borders of the spinous processes which they unite; they are continued below by the interlamellar liga- sy been ments, forming two lateral planes which are applied against each other, like the lamin of the cervical ligament, and covered outwardly by the transverse spinous (dorsalis colli) muscle. _ In the region of the neck, the interspinous ‘ligaments are yellow and elastic. In the dorso- lumbar region, they are formed by fasciculi of white fibrous tissue, loosely united to each other ‘at their extremities, and directed very obliquely ‘backwards and downwards. In consequence of this disposition, and notwithstanding their in- extensibility, they permit the separation of the jyyepverrepraL ARTICULA- ‘spinous processes. Their lateral surfaces are TIONS. vided by a layer of grey elastic fibres, which 4, n, c, Bodies of three dorsal ‘cross like an X the direction of the preceding —_ vertebra divided longitudi- ‘fasciculi. Very abundant in the anterior moiety ee veaious pay ia ‘of the dorsal region, these fibres operate, by their tervertebral discs; 2, Super- proper elasticity, = nom gc the spinous pro- spinous dorso-lumbar liga- ‘cesses towards each other. ment ; 3, Interspinous liga- ¢. Interlamellar, or interannular lgaments.— rah 4, eervee Rasiajene Bene celta no ro biel SS : t ( in the dorsal region, “moieties, these ligaments appear to be produced ‘by the two fibrous planes Mt the preceding ligaments, which, on arriving at the base of the spinous processes, separate from one another to be carried outwards. Their anterior border is inserted into the posterior margin of the vertebral lamina in front. Their posterior border is fixed to the anterior border and inferior face of the lamina behind. Their superior face 1s in relation with some spinal muscles, and their inferior face is in contact with the dura mater. Outwardly, they are confounded with the capsules proper 134 THE ARTICULATIONS. to the articular processes. Yellow and elastic in the cervical region, thes¢ ligaments are white and inelastic in the dorso-lumbar region. d. Capsules proper to the articular processes (Fig. 81, 5).—Each anterior articular process is maintained against the corresponding posterior process — by a direct band: this is a peripheric capsule attached around the diarthrodial facets, doubled internally by a synovial membrane which facilitates their gliding, and covered, outwardly, by the insertions of some spinal muscles. These capsules, yellow and elastic in the cervical, are composed of white fibrous tissue in the dorso-lumbar region. Very developed at the neck, in consequence of the thickness of the articular tubercles they envelope, they become reduced, near the middle of the back, to some fibres which cover, outwardly, the diarthrodial facets in contact, CHARACTERS PROPER TO SOME INTERVERTEBRAL AnrticuLaTiIons.—1, Inter- coccygeal and sacro-coccygeal articulations.—These are constructed after the same type as the other spinal articulations, except that they are appropriate to the rudimentary state of the vertebre they unite. The coceygeal bones only come in contact by their bodies, their spinal lamine being reduced to the merest traces, or are altogether absent. The anterior and posterior articular surfaces of each vertebra are convex, and the interarticular fibro-carti hollow on both faces, resemble a biconcave lense. With regard to the peripheral bands, they are represented by a bundle of longitudinal fibres spread over the surface of the bones, which they envelope in a common sheath, 2. Intersacral articulations.—The sacral vertebre being fused into one piece—the os sacrum—there is no occasion to study the true articulations in this region. It may be remarked, however, that the superspinous dorso- lumbar ligament is continued on the sacral spine, and that there exist be- tween the processes formed by this spine veritable interspinous ligaments. _ 3. Sacro-lumbar articulation.—In this articulation, the great thickness of the fibro-cartilage is to be remarked; and, in addition, that the last lumbar vertebra corresponds with the sacrum not only by its body and articular processes, but also by the oval and slightly concave facets shown on the posterior border of its transverse processes, which are adapted to analogous slightly-convex facets on the sides of the base of the sacrum. bundles of fibres thrown from one bone to another from around these saecro- transversals (real planiform diarthroses) maintain the articular surfaces in contact, and cover, outwardly, the synovial membrane which facilitates their gliding. 4, Articulation of the two last lumbar vertebree.—This is distinguished by the presence, between the transverse processes, of a planiform diarthrosis like that of the sacro-transversal just noticed. These two articulations are only found in Solipeds. 5. Atlo-axoid articulation.—This is so far removed by its conformation and special uses from the other intervertebral articulations, that it will be described as an extrinsic articulation of the head and spine. (See the Articulations of the Head.) Tue Movements or tHe SPINE IN GENERAL.—Each intervertebral articula- tion is the seat of very obscure movements, whose separate study offers little interest. But these movements, when conjoined with those of ‘the other articulations, result in bending the whole spinal stalk in a somewhat marked manner, and producing either the flexion, extension, or lateral inclination of this flexuous column. When flexion takes place, the spine is arched upwards, the common inferior ligament is relaxed, the spinous processes separate from one ARTICULATIONS OF THE HEAD, 135 ‘another, and the superspinous ligament, becoming very tense, soon imposes limits to this movement. : Extension is effected by an inverse mechanism, and is checked by the tension of the common inferior ligament and the meeting of the spinous ___—_— Lateral inclination takes place when the spine bends to one side. This movement is very easily executed in the cervical and coceygeal regions, but _ is arrested by the ribs and the costiform processes in the dorso-lumbar A circumflex movement is possible at the two extremities of the vertebral column—neck and tail; for they pass easily from extension to lateral amine’ =n from this to flexion, ete. ing to the elasticity of the intervertebral fibro-cartilages, the spine is endowed with a very limited amount of rotation, or rather of torsion. For the special study of the movements of each spinal region, reference must be made to what has been already said (page 29) regarding the mobility of this column. fourth, fifth, sixth, and seventh vertebre. The superior border of this auxiliary liga- mentous ion is concealed between the two lamina of the principal ligament.” ! The Pig, remarkable for the shortness of its neck and the limited movements of this region, does not show any cervical ligament, properly so called. It is replaced by a superficial fibrous raphé extending from the occipital bone to the spinous process of the first dorsal vertebra. The Cat has no cervical ligament, and shows, instead, a raphé like the Pig. In the Dog the ligament is reduced to a simple cord, continued from the dorso-lumbar ligament, and which goes no further than behind the spinous process of the axis. In the Cat the interspinous ligaments are replaced by small muscular fasciculi ;. with the Dog this substitution only takes place in the cervical region. The laminw of the first coceygeal vertebre possess the principal characters which distinguish perfect vertebra. ry & united by vestiges of the articular bands which exist in the other regions of ne. Articte Il.—Arricunations or THe Heap. _ We will first study the two extrinsic articulations which are the centre _ of the movements of the head on the spine—the atlo-axoid and oecipito-atloid _ articulations. Afterwards, we will pass to the examination of the joints which unite the different bones of the head. 1. Atlo-axoid Articulation. perma suffices to remove the soft parts from around the articulation to expose the interannular, the interspinous, and the inferior odontvid ligament. To examine i * ' «Journal de Médecine Vétérinaire’ (Lyons, 1818), p. 122. 136 THE ARTICULATIONS, the superior odontoid ligament and the gn membrane, one half the atlas and axis { must be separated by sawing longitudinally through them from one side to the other.) This may be considered-as the type of the trochoides. “a Articular surfaces —To form this articulation, the axis offers its odontoid i pivot and the undulated diarthrodial facets at its base. The atlas opposes ‘ to the pivot the concave semicylindrical surface hollowed on the superior face of its body; and for the lateral undulated facets it has analogous facets which are cut on the transverse processes, on each side of the vertebral canal. Mode of wnion.—1. An odontoid, or odonto-atloid ligament; 2. An inferior atlo-axoid ligament; 3. A superior ditto; 4. A fibrous capsule. a. Odontoid ligament (Fig. 81, 3).—Continued to the common superior vertebral ligament, very short and strong, flattened from above to below, and triangular in shape, the odontoid ligament is composed of glistening white. fibres, fixed behind in the superior channel of the odontoid process, and inserted in front on the transverse ridge which separates the superior face from the inferior arch of the atlas, as well as on the imprints situated in front of this ridge. This ligament is covered, on its lower face, by the synovial membrane of the articulation; and by its upper surface is in contact with the spinal dura mater. It sends some bands within the condyles of the occipital bone, . b. Inferior atlo-axcid ligament.—This is a wide, thin, and nacrous- looking band, extending from the inferior face of the axis to the inferior tubercle of the atlas, and covered by the long muscle of the neck; it is united to the synovial membrane by its deep face, and confounded on its borders with the fibrous capsule to be immediately described. e. Superior atlo-axoid ligament.—This exactly represents the inter- spinous ligaments of the other cervical articulations, Yellow, elastic, and — formed like the two lateral bands, it is continuous, laterally, with the capsular ligament. d, Capsular ligament.—This, it may be said, is only the interlamellar ligament proper to the atlo-axoid articulation. It commences from the sides of the preceding ligament, and becomes united to the inferior atlo- axoid one, after contracting adhesions with the borders of the odontoid ligament. In this way it encloses the articulation and the spinal canal. Before and behind, it is attached to the anterior or posterior margin of the bones it unites, Its external face is in contact with the great oblique muscle of the head; its internal responds, in its inferior half, to the arti synovial membrane, and its superior moiety to the spinal dura mater, (Leyh describes this ligament as the interannular.) Synovial membrane.—This lines the odontoid ligament, the atlo-axoid ligament, and the articular portion of the peripheral capsule. Movements.—Rotation, the only movement possible in the atlo-axoid articulation, is effected in the following manner; the axis remains fixed, and the first vertebra, drawn to one side chiefly by the great oblique muscle, rotates on the odontoid pivot, carrying the head with it. In the Dog and Cat the odontoid ligament is replaced by three particular ligaments : 1, Two lateral cords, rising in common from the summit of the odontoid process, and inserted, each on its own side, within the condyles of the occipital bone; 2, A transverse ligament, passing over the odontoid process, which it maintains in its place against the inferior arch of the atlas, and is attached by its extremities to the superior face of the latter. A small synovial capsule facilitates the gliding of the odontoid process beneath this ligament. ‘The articular synovial membrane always communicates with that of the occipito-atloid articulation. In the Pig the disposition is nearly the same gs in the Carniyora, ARTICULATIONS OF THE HEAD. 2. Occipito-atloid Articulation, 137 ration.—Dissect away all the soft parts that pass from the neck to the head and cover the articulation, and more particularly the flexor, the recti, and the small oblique muscles of the head. To expose the synovial membranes, open the sides of the capsular ligament.) This is a condyloid articulation. i surfaces.—In the atlas, the two cavities which replace the anterior articular processes and the heads of the other vertebrae; in the occipital bone, the two condyles flanking the sides of the occi- pital foramen. Mode of union.—A single capsular ligament en- velopes the entire articulation ; it is attached by its anterior border to the margin of the occipital con- dyles, and by its posterior to the anterior contour of the atlas. Thin and slightly elastic in its inferior half, this ligament presents, superiorly, four reinforcing fasciculi: two middle, which intercross in X—from whence the name “ cruciform,” sometimes given to this ligament (Fig. 81, 1, 1); and two lateral, which pass from the sides of the atlas to the base of the styloid processes (Fig. 81, 2,2). It is lined within by the synovial membranes, and is enveloped externally by a large number of muscles, which protect the articu- lation and greatly strengthen iteverywhere. Among these may be particularly noticed the straight muscles of the head, the small oblique, and the great com- plexus. There is also the cord of the cervical liga- ment. - Synovial membranes.—These membranes are two in number, one for each condyle and corresponding atloid cavity. Sustained above, below, and outwardly by the capsular ligament, they are related inwardly to the dura mater and tothe fibrous tractus which, from the odontoid ligament, is carried to the in- ternal face of the occipital condyles. Movements.—Extension, flexion, lateral inclination, and cireumduction, are the possible movements of the occipito-atloid articulation. In the Pig, Dog, and Cat this articulation, strengthened as it is by the capsular and odontoido-occipital ligaments already mentioned, has only one synovial capsule. 3. Articulations of the Bones of the Head. If we except the articulation which unites the inferior jaw to the cranium—the temporo-maxillary— and the hyoideal articulations, it will be found that all the bones of the cranium and face are united to each other by synarthrosis, forming the different kinds of sutures already generally described (page 128). Nothing is to be gained by entering into more detail ATLO-OXOID AND OCCIPI- TO-ATLOID ARTICULA- Tions. The upper arch of the atlas has been removed to show the odontoid ligament. 1, 1, Middle accessory fas- eiculi; 2, 2, Lateral fasciculi of the capsular . ligament of the occipito- atloid articulation; 3, Odontoid ligament; 4, Interspinous ligament uniting the second and third vertebre of the neck ; 5, Fibrous capsule uniting the articular processes of these verte- bre.—a, Anterior in- ternal foramen of the atlas converted into a groove by the section of the bone; B, B, Vertes bral foramina of the atlas; ¢c, ¢, Foramina replacing the anterior notches of the axis, 188 THE ARTICULATIONS. with regard to these articulations, as it will be found sufficient to call to mind the topographical description of each piece entering into their formation. 4. Temporo-maxillary Articulation, (Preparation.—Remove the masseter muscle and the parotid gland. Saw through the head about the middle line, Open the articulation externally to exhibit the inter- articular meniscus.) : The lower jaw, in its union with the cranium, constitutes a double condyloid articulation. : Articular surfaces—With the temporal bone, these are the condyle, the glenoid cavity, and the supracondyloid process which exists at the base of the zygomatic process. ‘The glenoid cavity is not lined by cartilage, and appears to be merely covered by synovial membrane. With the maxillary bone there is the oblong condyle situated in front of the coronoid process. Inierarticular fibro-cartilage—The articular surfaces just named are far from fitting each other accurately; this is only accomplished by the interposition of a fibro-cartilaginous disc between the temporal and maxillary bones. This disc isa kind of irregular plate, flattened above and below, thicker before than behind, and moulded on each of the diarthrodial surfaces it separates. Its superior face, therefore, presents: in front, a cavity to receive the condyle of the temporal bone; behind, a boss which is lodged in the glenoid cavity. The inferior face is hollowed by an oblong fossa in which the maxillary con- dyle is lodged. Mode of union.—A fibrous envelope—a true ae - you: capsular ligament—surrounds the articulation, ee to ce pene ee aed is attached by its borders to the margin of 1, Interarticular fibro-cartilage; the articular surfaces it unites. Formed, out- 2, External fasciculus of the wardly, by a thick fasciculus of white vertical ctrlasTament Ts of fibres (Fig. 82, 2), this ligament becomes grey- ofthe en a condyle; c, i8h-coloured and elastic for the remainder of Mastoid process; p, External its extent, and greatly diminishes in thickness, auditory hiatus. especially in front. Its inner face is lined by the synovial capsules, and adheres to the cir- cumference of the interarticular fibro-cartilage. Its external face responds, in front, to the temporal and masseter muscles; behind, to the parotid gland; inwardly, to the external pterygoid muscle; and outwardly, to a fibrous expansion which separates it from the skin, (Leyh mentions a lateral external and a posterior ligament for this articulation, but Chauveau and Rigot evidently look upon these as portions of the capsular.) - Synovial membranes.—This articulation has two synovial sacs, one above the other, which are separated by the fibro-cartilaginous disc. Movements.—The temporo-maxillary articulation is the centre of all the movements performed by the lower jaw. ‘These are: depression, elevation, lateral motion, and horizontal gliding. The lower jaw is depressed when it separates from the superior one, and is elevated when it approaches this. These two opposite movements are executed by a mechanism of such great simplicity that it need not be Fig. 82. ARTICULATIONS OF THE HEAD, 139 described here. Lateral movements take place when the inferior extremity of the jaw is carried alternately to the right and left. It then happens that one of the maxillary condyles, taking with it the fibro-cartilage, is brought . into contact with the temporal condyle, while the other is imbedded in the cena cavity of the opposite side. The horizontal gliding is effected from ind to before, or vice versd. In the first case, the two maxillary condyles are carried at the same time under the temporal condyles, bearing with them the fibro-cartilages. In- the second case, they are drawn into the glenoid cavities, and rest against the supracondyloid eminence, which vents their going further. It will be understood, after this brief Beitiintion, that the presence of the fibro-cartilages singularly favours the lateral movements and horizontal gliding of the lower jaw. In the Pig the temporo-maxillary articulation is formed after the same type as that of rodents, and ‘allows very extensive movements from before to behind; a circumstance due to the complete absence of the supracondyloid eminence. In the Dog and Cat the maxillary condyle is exactly fitted into the temporal cavity. This disposition, in giving great precision to the movements of depression and elevation, restrains in a singular manner the lateral and horizontal gliding motions,. The inter- _ articular fibro-cartilage is extremely thin in these animals. 6. Hyoideal Avticulaiions. _ (Preparation.—Disarticulate the lower jaw, and dissect away from the right of each articulation the muscles that may conceal the view.) _ These are of two kinds: extrinsic and intrinsic. The first comprise the two temporohyoideal articulations ; to the second belong the joints which unite the different pieces of the hyoid hone—the interhyoideal articulations. Temroro-HyomEAL ArtIcuLATIONS.—These are two amphiarthrodial joints, in the formation of which cach great branch of the hyoid bone opposes its upper extremity to the hyoideal prolongation lodged in the vaginal sheath of the temporal bone. An elastic cartilage, from 4-10ths to 6-LOths of an inch in length, unites the two bones in a solid manner; and it is owing to the flexibility of this cartilage that the hyoid bone can move entirely on the temporal bones. InrernyomraL Articutations.—A, The great branch articulates with the small one by an amphiarthrosis analogous to the preceding. To form . this articulation, these two pieces of bone are joined at an acute angle through the medium of a more or less thick cartilaginous band, in the centre of which there is often a little bony nucleus. This cartilage is elastic and flexible, and permits the opening and closing of the articular angle at the summit of which it is placed. B. Each small branch is united to the body of the hyoid bone by an arthrodial articulation. The articular surfaces are; for the hyoideal branch, the small cavity terminating its inferior extremity; for the body, the rounded lateral facet situated at the origin of the cornu. These surfaces are covered by cartilage, and enveloped by a small synovial sac and a kena fibrous capsule. They can glide on each other in nearly every irection, (Median and superior hyoideal capsular ligaments are described by Leyh as sometimes present. The latter unites the upper and middle branches, and the former the middle with the inferior branches, They are absent when these branches are confounded with the superior ones.) 340 THE ARTICULATIONS. Articte ITI.—Articunations or tHe THorax. These are also divided into extrinsic and intrinsic. The first, named costo-vertebral, unite the ribs to the spine. The second join the different pieces of the thorax together; they comprise: 1, The chondro-sternal articulations ; 2, Chondro-costal articulations; 8, The articulations of the costal cartilages with each other; 4, The sternal articulation peculiar to the larger Ruminants and the Pig. All these joints will be first studied ina particular manner, then examined in a general way as to their movements, — 1. Articulations of the Ribs with the Vertebral Column, or Costo-vertebral Articulations. Each rib responds to the vertebral column by two points—its head and its tuberosity. The first is received into one of the intervertebral cavities hollowed out on the sides of the spine, and is therefore in contact with two dorsal vertebrae; the second rests against the transverse process of the yosterior vertebra. From this arrangement arises two particular articulations longing'to the arthrodial class, which are named costo-vertebral and costo- transverse. , Cosro-verTEBRAL ArticuLaTions.—Articular surfaces.—Pertaining to the rib, we have the two convex facets of the head, separated from each other by a groove of insertion and covered by a thin layer of cartilage. On the vertebr, the concave facets which by their union form the inter- vertebral cavity ; these facets are also covered with cartilage, and separated, at the bottom of the cavity by the corresponding intervertebral dise. _ Mode of wnion.—1. An interarticular ligament (Figs. 83, 2; 84, 1), im- planted in the groove of insertion of the head of the rib, and attached to Fig. 83, Fig. 84, ARTICULATIONS OF THE RIBS WITH THE VER- ARTICULATIONS OF THE RIBS WITH THE VER- TEBRA, AND OF THESE WITH EACH OTHER TEBR&, AND OF THESE WITH EACH OTHER (UPPER PLANE). : (INFERIOR, PLANE). 1, Spinal canal, upper face, showing the 1, Interarticular costo-vertebral ligament; common superior ligament; 2, Interar- 2, 3, 4, Fasciculi of the stellate, or in- ticular costo-vertebral ligament; 3, Inter- ferior costo-vertebral ligament ; 5, Common osseous costo-transverse ligament; 4, Pos- inferior vertebral ligament, terior costo-transverse ligament. the superior border of the intervertebral disc, which it encircles upwards and inwards, to unite on the median line with the ligament of the opposite side. 2. An inferior peripherai ligament (Fig. 84, 2, 3, 4), flat above and below, thin and radiating (whence it is often named the stellate ligament), formed of three fasciculi which are fixed in common on the inferior face of ARTICULATIONS OF THE THORAX. 141 the head of the rib, and in diverging are carried over the bodiés of the two vertebrae and the intervertebral disc. Lined above by the synovial mem- branes, this ligament is covered below by the pleura. (Leyh includes a ligament for the head of the rib and another for the costal ity. He probably viewed the synovial membrane of these articula- tions as such.) ; ial membranes.—Two in number, these are distinguished into anterior and posterior, lying against each other, and separated in part by the interarticular ligament they cover. Supported below by the stellate ligament, above they are directly in contact with the small supercostal muscles, and with vessels and nerves. Costo-rransversE ArticuLations.—Articular surfaces.—In the rib, the diarthrodial facet cut on the tuberosity. In the vertebra, the analogous facet on the outside of the transverse process. _ Mode of union.—Two ligaments bind this articulation: 1, The posterior costo-transverse ligament (Fig. 83, 4), a white fibrous band attached by its extremities behind the tranverse process and the costal tuberosity, lined by Synovial membrane, and covered by the transverse insertions of several spinal muscles; 2, The anterior costo-transverse, or interosseous ligament (Pig. 83, 3), a fasciculus of short, thick, white fibres, fixed on the anterior of the transverse process near its base, and in the rugged excavation on the neck of the rib. This ligament is invested, posteriorly, by the synovial membrane, and covered in front by pads of adipose tissue which separate it from the costo-vertebral articulation. Synovial membrane.—This is a small particular capsule kept apart from the posterior synovial membrane of the costo-vertebral articulation by the costo-transverse interosseous ligament. ; CHARACTERS PECULIAR TO soME CosTO-VERTEBRAL ARTICULATIONS.— 1. The first, and sometimes the second, costo-vertebral articulation has no interosseous ligament, and only exhibits one synovial membrane. The intervertebral cavity which concurs in forming the first is often excavated between the last cervical and first dorsal vertebra. 2. The two or three last costo-transverse articulations are confounded with the corresponding costo-vertebral joints. They have no proper serous membrane, but the posterior synovial membrane of the latter is prolonged around their articular surfaces. 2. The Chondro-sternal or Costo-sternal Articulations. (Preparation.—To show the articulation of the ribs with the cartilages, these with the sternum, and the cartilages with each other, carefully remove the pleura, the triangular muscle of the sternum, the diaphragm, the transverse muscle of the abdomen, then the pectorals, the great oblique, the transversalis of the ribs, and the intercostal muscles. ) \ The first eight ribs, in resting upon the sternum by the inferior extremity of their cartilages, form eight similar arthrodial articulations. ' Articular surfaces.—Each sternal cartilage opposes to one of the lateral cavities of the sternum the convex and oblong favet at its lower extremity. Mode of wnion.—The diarthrosis resulting from the union of these two surfaces is enveloped everywhere by bundles of white, radiating, fibrous _ tissue, which constitute a veritable ligamentous capsule. The superior part of this capsule, known as the stellate or superior costo-sternal ligament, is covered by the triangular (sterno-costalis internus) muscle; it is joined to a fibrous cord lying on the superior face of the sternum, and which 142 THE ARTICULATIONS, is confounded in front with that of the opposite side. ‘Tho inferior portion, the inferior stellate or costo-sternal ligament, is in relation with the pectoral muscles. Synovial capsule.—There is one for each articulation. Characters proper to the first costo-sternal articulation.—The first costo- sternal articulation is not separated from its fellow of the opposite side; so that these two joints are, in reality, only one, and the two cartilages lyi close to each other correspond by a small diarthrodial facet, continuous with — that for the sternum. The two sternal facets are inclined upwards, and — confounded with one another. Only one synovial cavity exists for this complex articulation, which unites the two first ribs to each other and to the sternum. 3. Chrondo-costal Articulations uniting the Ribs to their Cartilages. These are synarthrodial articulations whose movements are very obscure. They are formed by the implantation of the cartilages in the rugged cavities the ribs present at their inferior extremities, The solidity of these artieu- lations is assured by the adherence of the fibro-cartilage to the proper substance of the ribs, and by the periosteum which, in passing from the bone to the cartilage, plays the part of a powerful peripheral band. In the Ox, the sternal ribs, in uniting with their cartilages, form a veritable ginglymoid diarthrosis, whose movement is facilitated by a small synovial capsule, 4, Articulations of the Costal Cartilages with each other. The ribs, attached to each other by means of the intercostal muscles, are not united by real articulations; neither are their cartilages of prolongment. But the asternal cartilages are bound together by a small yellow elastic ligament, which is carried from the free extremity of each to the posterior border of the preceding cartilage; the anterior border of the first asternal cartilage is directly united to the posterior border of the last sternal cartil through the medium of the perichondrium and very short ligamentous bands This same asternal cartilage is also bound to the inferior face of the xiphoid appendage by a small white ligament (the chondro-wiphoid), under which passes the anterior abdominal artery. 5. Sternal Articulation peculiur to the Ox and Pig. It has been already shown that in these animals the anterior piece of the sternum is not consolidated with the second portion. The two are united by a diarthrodial articulation ; and for this purpose the anterior presents a concave surface, the posterior a convex one. Bundles of peripheral fibres firmly bind them to each other, and a special small synovial capsule facilitates their movements, which are very limited, 6. The Articulations of the Thorax considered in a general manner in regard to Movements. The thorax can increase or diminish in diameter in an antero-posterior and a transverse direction; whence arises the dilatation and contraction of this cavity: the inspiratory movements accompanying the entrance of the external air into the lungs, and the expiratory movements expelling the air contained in these organs, The variations in the antero-posterior diameter of the chest being due to changes in the figure of the diaphragm, need not be noticed here. But the transverse variations being the result of the play of the costal arches on the =.” ee ARTICULATIONS OF THE ANTERIOR LIMBS, 143 spine and sternum, it is advantageous to study the mechanism which presides in the execution of their movements. The costal arches being inclined backwards on the middle plane, the space they inclose in their concavity is not nearly so extensive as if they had been perpendicular to this plane. Owing to their double arthrodial joints, the ribs are movable on the spine, and their inferior extremity, also movable, rests either directly or indirectly on the sternum. Therefore it is that, when they are drawn forward by their middle portions, they pivot on their extremities, and tend to assume a perpendicular direction, which is the most favourable for the largest increase of the space they limit; then there is enlargement of the lateral diameter of the thorax, which signifies dilatation of its cavity. The inverse movement, by an opposite mechanism, causes the contraction of the chest. The ribs are said to be elevated during the forward movement, and depressed when they fall backwards. These expressions, though perfectly applicable to Man, who stands in a vertical position, are not correct when employed in veterinary anatomy. Articte TV.—ArtTIcULATIONS OF THE ANTERIOR Loss. 1. Scapulo-humeral Articulation. (Preparation.—Detach the limb from the trunk. Remove from the upper extremity those muscles which are inserted in the vicinity of the glenoid cavity of the scapula; turn down from its lower extremity those which are inserted into the superior end of the humerus or a little below, preserving the attachments of their tendons with the ligament. The thin scapulo-humeralis muscle may be allowed to remain in oO to show its relations.) To constitute this enarthrodial articulation, the scapula is united to the humerus, and forms an obtuse angle which is open behind. Articular surfaces.—In the scapula there is the glenoid cavity, the shallow, oval fossa, elongated in an antero-posterior direction, notched in- wardly,and excavated at its centre or near the internal notch by a small synovial fossette. A ligamentous band, attached to the brim of the cavity, fills up this notch, and is the vestige of the glenoid ligament of man. In the humerus, the articular head, fixed between the large and small tuberosities, is often excavated by a shallow synovial fossette. Mode of union—One capsular ligament (Fig. 85, 1), a kind of sac having two openings: one inferior, embracing the head of the humerus; the superior, inserted into the margin of the glenoid cavity. This capsule pre- sents in front two supporting fasciculi, which diverge as they descend from the coracoid process to the great and small tuberosities. The aponeurotic expansion thus formed is very thin and loose, so as to allow the two bones to te to the extent of from ,4, to ;4; of an inch; but it is far from being sufficiently strong to bind them firmly together. The articulation is, therefore, consolidated by the powerful muscles which surround it, among which may be noticed: 1, In front, the coraco-radial (flexor brachii), separated from the fibrous capsule by an adipose cushion; 2, Behind, the large extensor of the fore-arm and thin scapulo-humeral (teres minor) muscles, whose office appears to be to pull up this capsule during the move- ments of flexion, so as to prevent its being pinched between the articular surfaces; 8, Outwards, the short abductor of the arm and the subspinous (postea spinatus) tendon; 4, Inwards, the wide and strong tendon of the subscapular muscle. In addition to these powerful retaining apparatus, ‘ » 144 THE ARTICULATIONS. : — | there is the atmospheric pressure, whose influence is of a certain impors 1 4 tance. This may be proved by removing all the surrounding museles, ‘orl it will be found that the capsule is not relaxed, nor are the articular surfaces separated ; to effect this, it is necessary to make an opening in the capsule, so as to allow the air to enter its cavity, when the surfaces immediately __ separate. ’ . Synovial capsule.—This is very loose, and entirely enveloped by the peripheral capsule, whose internal surface it lines, Movements.—Like all the enarthrodial articulations, the seapulo-hu permits extension, flexion, abduction, adduction, cireumduction, and rotation, These various movements, however, are far from being so extensive as in Man, the arm in the domesticated animals not being detached from the trunk, but being, on the contrary, fixed with the shoulder against the lateral parietes of the thorax. Flexion and extension are the least limited and the most frequently repeated movements; their execution always demands a displacement of the two bones, which are almost equally movable. In flexion, the scapulo-humeral angle is closed, not only because the inferior extremity of the humerus is carried backwards and upwards, but also because the scapula pivots on its superior attachments in such a manner as to throw its glenoid angle forward and upward. ztension is produced by an inverse mechanism. During the execution of the other movements, the scapula remains fixed, and the humerus alone is displaced, bringing with it the inferior rays of the limbs. If it is carried outwards, we have abduction, or inwards, adduction; if the member passes successively from flexion to abduction, and from that to extension, etc., in describing a circle by its lower extremity, then there is circumduction; if it pivots from left to right, or right to left, we have rotation. In the Pig, Dog, and Cat, the synovial membrane is not exactly inclosed by the fibrous capsule, but forms in front a cul-de-sac, which descends in the bic’ pital groove to favour the gliding of the coraco-radial tendon. In Man, the scapulo-humeral articulation is disposed as in animals, but it is also protected above by the coraco-acrumion roof. For the reasons noted above, this articulat‘on allows of more extensive motion than in animals, As remarked by . Cruveilhier, of all the joints in the human body, the scapulo-lumeral is that which has the most extensive motion; in movements furward and outward, the humerus can become horizontal; in those of cireumduction it describes a complete cone, which is more extensive in front and laterally than behind and inwardly. 2. Humero-radial, or Elbow Articulation. (Preparation.—Turn down the inferior extremity of the flexors of the fore-arm, remove the olecranian, epicondyloid, and epitrochlean muscles, taking care nut to damage the ligaments to which they somewhat closcly adhere.) Three bones -concur to form this articulation, which presents a remark- able example of an angular ginglymus: the humerus, by its inferior ex- tremity, and the two bones of the arm by their upper extremities. Articular surfaces.—The humeral surface, already described at page 74, is transversely elongated, and convex from before to behind. It presents: 1, A median groove excavated by a synovial fossette; 2, An external groove (humeral trochlea) not so deep as the preceding; 3, A kind of voluminous condyle which borders, inwardly, the internal pulley, and whose antero- posterior diameter is much greater than that of the external lip of the trochlea of the opposite side. The antibrachial surface, divided into two portions, is moulded to the humeral surface ; it is, therefore, concave hefore and béhind, and is composed; 1, Of a double external groove; 2, Of an ARTICULATIONS OF THE ANTERIOR LIMBS. 145 ay - sinter cavity, both excavated, on the superior extremity of the , A middle ridge re- ante to the middle groove the humerus, separating the g surfaces, and Biaonged on the ulnar beak, where it forms the sygmoid notch. This ridge shows a small synovial fossette hol- lowed out on the radius and ulna. _ Mode of wunion—Three ligaments : two lateral and an anterior. a. The external lateral liga- ment (Fig. 85, 8) is a thick, short, and strong funicle, at- tached above to the crest limit- ing outwardly and posteriorly the furrow of torsion, and in the small cavity placed at the external side of the humeral articular surface. Below, it is inserted into the supero-ex- ternal tuberosity of the radius. Its anterior. border is con- founded with the capsular liga- ment, and is margined by the — rincipal extensor of the pha- , which derives from it numerous points of attach- ment. By its posterior border it is in contact with the ex- ternal flexor of the metacarpus. Its internal face is lined by synovial membrane, and its external face is only separated from the skin by the anti- brachial aponeurosis and some of the fasciculi from the origin of the lateral extensor muscle ‘of the phalanges. Its super- ficial fibres are vertical, and are continuous, behind, with the arciform ligamentous bands ‘which stretch from the ulna to the radius. Its deep fibres are o> paul a downwards b. The lateral internal liga- ment, also funicular, is longer, but not so strong as the pre- ceding. SCAPULO-HUMERAL AND Fig. 85. HUMERO-RADIAL ARTICU- LATIONS, WITHTHE MUSCLES SURROUNDING THEM (EXTERNAL FACE). 1, Scapulo-humeral capsular ligament; 2, Short ab- ductor muscle of the arm; 3, Its insertion in the humerus; 4, Insertion of the subspinous muscle on the crest of the great tuberosity; 5, Coraco- radial muscle; 6, Its tendon of origin attached to the coracoid process; 7, Its radial insertion con- founded with the anterior ligament of the ulnar articulation; 8, 8, External lateral ligament of that articulation; 9, Anterior ligament; 10, Aconeus, or small extensor of the fore-arm; 11, Origin’ of the external flexor muscle of the metacarpus; 12, Short flexor muscle of the fore-arm.—aA, Tuberosity of the scapular spine.—n, Superspinous fossa.—c, Sub- spinous fossa.—p, Convexity of the small trochan- ter.—r, Summit of the trochanter, It arises from the small tuberosity on the inner side of the L ty 3 oF ee it , si 46 THE ARTICULATIONS, superior articular face of the humerus and, widening as it descends, reaches the radius. Its median fibres, which are the longest, are directed vertically downwards to reach the imprints situated below the bicipital tuberosity ; its anterior fibres, curved forwards, are united to the tendon of the coraco- radial muscle, or are confounded with the anterior ligament; the posterior are turned backwards, near their inferior extremities, to join the arciform fibrous fasciculi which inwardly unite the ulna to the radius, The middle fibres of this ligament cover the inferior insertion of the short flexor of the — fore-arm and, in part only, that of the long flexor. It is covered by the — ulna-plantar nerve and the posterior radial artery and vein. ce. The anterior or capsular ligament (Fig. 85, 9) is a membraniform band, attached by its superior border above the humeral articular surface, and by its inferior to the anterior margin of the radial surface. By its lateral borders, it is confounded with the funicular ligaments. Its internal half is formed of vertical fibres which descend from the humerus and — over the radius, where they become united with the inferior tendon of the coraco-radial muscle. In its external moicty it is extremely thin, and composed of fibres crossed in various directions, Lined internally synovial membrane, this ligament is in contact, by its external surface, with the anterior radial vessels and nerves, the two flexor muscles of the fore-arm, the anterior extensor of the metacarpus, and anterior extensor of the phalanges. The two latter muscles are even attached to it in a very evident manner. The elbow articulation, closed in front and on the sides by the three ligaments just described, has no particular ligaments posteriorly ; but it is powerfully consolidated there by the olecranian insertion of the extensor muscles of the fore-arm, and by the tendons of origin of the five flexor muscles of the metacarpus or phalanges. Synovial membrane.—This membrane is very extensive and, stretched out on the internal face of the before-mentioned ligaments, forms behind three great culs-de-sac of prolongment : a superior, occupying the olecranian fossa, and covered by a fatty cushion, as well as by the small! extensor muscle of the fore-arm ;! two lateral, which descend from each side of the ulnar beak, and are distinguished as internal and external; the first lines the tendon of the external flexor of the metacarpus; the second facilitates the play on the upper radial extremity of the four flexor muscles of the foot or digits, and which are attached in common to the epitrochlea. This synovial sac also furnishes the radio-ulnar articulation with a diverticulum which descends between the bones of the fore-arm to below the adjacent diar- throdial facets. Movements.—Flexion and extension. In flexion, the two bones do not approach each other directly, the inferior extremity of the radius deviating a little odtwards. This is due more to the slight obliquity of the articular grooves than to the difference in thickness existing between the external and internal extremities of the humeral surface. . Extension is limited by the reception of the beak of the olecranon in its fossa, and by the tension of the lateral ligaments; so that the two rays cannot be straightened on one another in a complete manner, or placed on the same line. In the Dog and Cat, the external lateral ligament is very thick, and forms in its ' Some grey elastic fibres which cover this cul-de-sac externally, have been wrongly described as a posterior membraniform ligament, ' ARTICULATIONS OF THE ANTERIOR LIMBS. 147 “te moiety a fibro-cartilaginous cap which is fixed on the ulna and radius, and united tothe annular ligament of the superior radio-ulnar joint. This cap, with the last- pennent, completes the osteo-fibrous ring in which the superior extremity of the he internal lateral ligament is inserted by two very short fasciculi into he ulna and inner side of the head of the radius. A third fasciculus, deeper and median, mu hag developed than the first, and covered by the inferior insertion of the flexors the fore-arm, descends between the radius and ulna to the posterior face of the - former, and is there inserted near the inferior attachment of the external ligament, ‘it appears as if about to join. ____In Man, the elbow articulation is formed nearly on the same plan as that of the Do og ‘and Cat. The radius and ulna move together when the fore-arm is flexed and extend on the humerus. 3. Radio-ulnar Articulation. Articular surfaces—The two bones of the fore-arm correspond by - diarthrodial and synarthrodial surfaces. a. The diarthrodial surfaces consist of four undulated, transversely rag two. of which rae a and tt ead The first border, posteriorly, the t articular ace forming the elbow joint; the second cob leaks Sakecth the sigmoid notch. b. The synarthrodial surfaces are plane and roughened, and are also two on each bone: one, superior, extends below the diarthrodial facets to the radio-ulnar arch; the other, inferior, more extensive, occupies all the anterior face of the ulna from this arch; on the radius it forms a very elongated triangular.imprint which descends to the lower fourth of the bone. idee tess 75, 76. Mode o of union.—Two interosseous and two peripheral ligaments. ' a. The interosseous ligaments, interposed between the synarthrodial _ surfaces, are composed of extremely short white fibres passing from one to the other surface, and which are endowed with a very remarkable power of resistance. The inferior always ossifies a long time before the animal is full grown: a circumstance which caused the older veterinary anatomists to describe, and with some show of reason, the radius and ulna as a single bone. Ossification of the superior ligament is very rare. b. The peripheral bands are bundles of arciform fibres which, from the beak of the olecranon to the radio-ulnar arch, leave the lateral faces of the ulna to pass, some inwards, others outwards, to the posterior face of the radius. The fibres of the external ligament are confounded with the external humero-radial Lemocest The internal fibres are united to the internal humero-radial sia and to the small ulnar tendon belonging to the short flexor of the arm. Analogous fibres are found beneath the radio-ulnar arch; but they are much shorter and less apparent. (This is the external transverse radio-ulnar ligament of Leyh. _ Movements.—Very obscure in youth; nearly null when consolidation of _ the two bones takes place. In the Oz, ossification of the superior interosseous ligament is constant at adult a ia the Dog and Cat, we have already seen (p. 87) that the radius and ulna are not penn to each other, but remain independent during life. They are united in their . rtion by an interosseous ligament, and join by diarthrosis at their two Neetentilen These animals therefore exhibit: 1, An interosseous ligament; 2, A alba radio-ulnar articulation; 3, An inferior radio-ulnar articulation. t.—It is com of very resisting white fibres, attached by a their extremities the bodies of the bones. Notwithstanding their shortness, they are gy tener ag to ote movements taking place between the radio-ulnar articulations, Superior radio-ulnar articulation.—This is a trochoid articulation, which only allows movements of rotation or pivoting. 2 L 148 THE ARTICULATIONS. 8 A. 3 < ss = F] z a 2 Ez. $ 2 z ¢ E . a a 5 eS : 2 = . = R 8 < cartilage in its bony portion, and lined by synovial membrane—that of the elbow articulation—in its ligamentous portion. The head or superior extremity of the radius is also inerusted over its entire contour with a layer of cartilage: a disposition which permits it to glide not only in the concave face of the small sigmoid cavity, but also on the internal face of the two ligaments which complete this cavity. 5s fess Inferior radio-ulnar articulation.—This is also a trochoid articulation ae the preceding, but inversely disposed. Thus, the concave articular surface is on the radius, outside the inferior extremity; the convex surface lies within the ulna. These two facets are very small, and are maintained in contact by a diminutive periph«ral fibrous capsule. A strong interosseous ligament, situated under articular facets, also consolidates this diarthrosis, and concurs by its inferior border to form the antibrachial surface of the radio-carpal articulation. A small synovial capsule is specially devoted to this articulation. a _ Mechanism of the radio-ulnar joints—The play of these two articulations is simultaneous, and tends to the same end; thit is, to the execution of the double rotatory movement which constitutes supination and pronation. Supination is when the ulna remains fixed rat the radius pivots on it in such a manner as to carry its anterior face outwards. Its superior extremity then turns from within forwards, and even from before outwards if the movement is exaggerated, in the articular girdle formed by the small sigmoid cavity of the ulua and the ligaments which complete it. The inferior extremity also rolls on the ulnar facet in describing a similar movement, and the internal tuberosity of this extremity is carried forwards. In the movement of pronation, this tuberosity is brought inwards, and the anterior face of the radius comes forward by an opposite mechanism. The inferior ray of the anterior member being articulated in a hinge-like manner with the radius, it follows that bone in its rotatory. movements, the anterior face of the metacarpus looking outwards during supination and forwards in pronation. ; The radio-ulnar articulation in Man resembles that of the Dog and Cat, the articular surfaces only being larger and the movements more extensive. In supination, the lmar face is turned forward, and the radius, situated on the outer side of the ulna, is in the same direction as the latter. In pronation, on the contrary, the palmar face of the hand looks backwards, and the radius, remaining outwards in its be oe part, crosses the ulna in front in such a manner that its lower extremity is placed within the ulna. — 4, Articulations of the Carpus. (Preparation —Remove the tendons from around the articulation, detaching their sheaths, but taking care of the ligaments.) These comprise: 1, The articulations wiiting the carpal bones of the first row to each other; 2, The analogous articulations of the second row ; 3, The radio-carpal articulation ; 4, The articulation of the two rows with each other ; 5, The carpo-metacarpal articulation. ARTICULATIONS WHICH UNITE THE Bones or tHE Finst Row To RACH otHeR.—These bones, four in number, are joined by the diarthrodial facets on their lateral faces and form small arthrodial articulations. They are maintained in contact by six ligaments, three anterior, and three interosseous. The anterior ligaments are small flattened bands carried from the fourth bone to the first, from the first to the second, and from that to the third. The first, placed outside rather than in front of the carpus, is covered by the 1 The facet uniting the supercarpal to the first bone is not situated on one of its faces, but rather on the anterior part of its circumference. , 4 ARTICULATIONS OF THE ANTERIOR LIMBS, 149 external lateral ligament and the inferior tendon of the external flexor of the metacarpus; the others adhere to the capsular ligament. The inter- _ osseous ligaments are implanted in the grooves of insertion which separate the diarthrodial facets. One of them, derived from the common superior ligament, unites the first to the second bone. The two others, situated between the three last carpal bones, are confounded with the corresponding anterior ligaments. _ ARqrIouLaTIons uNnITING THE CARPAL Boyes or THE Seconp Row.— These are arthrodial articulations, like the preceding, but numbering only two. They are fixed by two anterior and two interosseous ligaments. One of the anterior ligaments joins the first bone to the second, and strongly adheres to the capsular ligament ; the other is entirely covered by the lateral internal ligament, and attaches the two last bones to each other. Of the two inter- osseous ligaments, the second alone is confounded with the corresponding anterior ligament. That which is situated between the two first bones is separated from the anterior ligament by one of the diarthrodial facets between these bones. Rapro-carpat Articutation.—The inferior extremity of the radius, in becoming united to the upper row of carpal bones, constitutes a diarthrosis which, from the nature of the movements it permits, may be considered as an imperfect hinge joint. Articular surfaces—The radial surface, elongated transversely and very 2, pee presents: 1, Outwardly, a wide groove, limited in front by a glenoid cavity, and bounded, posteriorly, by a non-articular excavation which receives a prolongation of the second bone in the movement of flexion ; 2, Inwardly, a condyle, with a more extensive curvature than that of the preceding groove and, like it, completed by a small anterior glenoid cavity. The carpal surface, moulded exactly on the radial, offers depressions corre- sponding to the projections on it, and vice versd, Mode of union.—The radio-carpal articulation is bound by three liga- '_ments*which entirely belong to it, and by four strong ligaments that are common to it and articulations which will be studied hereafter. Of the three ligaments proper belonging to the radio-carpal articulation, one forms a thick, rounded funicle, extending from the radius to the fourth bone in an oblique direction downwards and inwards, and concealed by the common posterior ligament. The second (Fig. 87. 5), much smaller, is carried from the supercarpal bone to the external side of the inferior extremity of the radius, and is partly covered by the common external ligament. When the synovial capsule is distended by dropsy, it may form a hernia at the outer side of the carpus, by passing between this small ligament and the common posterior ligament. The third, very delicate, but always present, is deeply situated beneath the last; it is inserted, for one part, into the radius near the first proper ligament, and for the other, into the second bone and the interosseous ligament which unites the supercarpal to the second bone. Synovial membrane.—After lining these three ligaments and the four 5 age ligaments yet to be described, this membrane is prolonged between three first carpal bones to cover the superior face of the interosseous ligaments which unite them. It even more frequently descends into the articulation which joins the supercarpal to the first bone; though it also _ Sometimes happens that this has a particular synovial capsule of its own. _ Arricunation or tue Two Rows spetween Eacn Oruer.—Like the preceding, this is an imperfect hinge articulation. 150 THE ARTICULATIONS. Articular surfaces.—These are two, and are both transversely elongated, very irregular in their configuration, and divided into three portions. The ie: inferior shows: behind, three small condyles placed side by side; in front, ~ two slightly concave facets. The superior corresponds to the first by three glenoid cavities and two convex facets. : Mode of wnion—For this articulation, besides the common great liga- ments, there are three particular ligaments. Two of these are very short, and are situated behind the carpus, underneath the great common ps ligament, Dhey are readily perceived by removing the capsular ligament, and strongly flexing the carpus. “The strongest extends vertically from the internal bone of the superior row to the second and third bones of the metacarpal row; the other descends obliquely from the first bone of the antibrachial row to the second of the inferior row.”—Rigot. The third ligament proper, much stronger than the other two, reaches from the supercarpal to the first bone of the inferior row and the head of the external metacarpal bone. It is confounded, outwardly, with the great external lateral ligament; inwardly, with the common posterior ligament. Its posterior border gives attachment to the fibrous arch which completes the carpal sheath. This ligament has also a branch which is fixed on the _ second bone of the upper row (Fig. 87, 4). - . Synovial membrane.—This lines all the ligaments, and is prolonged above and below, between the carpal bones, to facilitate the gliding of their articular facets. Two upper pro- longations ascend between the three first bones of the antibrachial row te cover the inferior face of the inter- osseous ligaments uniting them. Two other prolong- ations descend between the carpal bones of the second row; the external, after covering the first interosseous ligament, passes between it and the corresponding an- terior ligament, and communicates with the synovial capsule of the carpo-metacarpal articulation. The in- ternal forms a cul-de-sac which rests on the inter- osseous ligament. Carro-MeracarpaL ArticuLaTion.—The bones of the second row articulate with the superior extremity of the metacarpal bones, constituting a plani- carpaL arricuta- form diarthrosis. TIONS; FRONT VIEW. Articular surfaces.—These are, on each side, plane 1, 1, Anterior liga- facets more or less inclined one on the another, and ments uniting the continued between each other. The largest is in the carpal bones of each middle, and is gencedii hollowed by a small, shallow, ed bh Anterior ‘synovial fossette. ras poe ge as, Mode of union.—There are the four great common pal articulation; 3, ligaments, and also six special ligaments: two anterior, Common — external. ¢y99 posterior, and two interosseous. aaa entcrnal liga, ,,. Of the to anterior ligaments (Fig. 86, 2, 2), one is way divided into two distinct bands, and unites the second bone to the principal metacarpal; the other, concealed by the external lateral ligament, attaches the first bone to the head of the external metacarpal bone, The two posterior ligaments described by Rigot do not appear to us to be sufficiently distinct from the great ligament to merit a special deseription. The two interosseous ligaments, completely overlooked by that able ical ee ARTICULATIONS OF THE ANTERIOR LIMBS. 151 anatomist, start from the interstices which separate the median m bone from the lateral me tacarpals, and join the interosseous ligaments of the second row; they are thick and short. We have sometimes noted one or’ other of them to be absent. Synovial membrane.—This communicates, as indicated above, with the a capsule of the preceding articulation. It furnishes a superior eul- which rests on the interosseous ligament interposed between the two last carpal bones of tlre second row. ‘T'wo inferior culs-de-sac descend into the intermetacarpal arthrodial articulations. LIGAMENTS COMMON TO THE THREE PRECEDING ARTICULATIONS, — As before mentioned, these are four in number: two lateral, one anterior, and one posterior. a. The external lateral ligament (Figs. 86 and 87, 3) is a thick funicular cord composed of two orders of fibres—a deep- seated and a superficial order, slightly crossed. It leaves the external and inferior tuberosity of the radius, descends vertically to the side of the carpus, transmits a fasciculus to the first bone of the upper row, gives off another fasci- culus which stops at the external bone of the second row, and terminates on the head of the corresponding metacar- pal bone. Traversed obliquely by the lateral exteusor of the this ligament covers the external carpal bones. In front, it is united to the capsular ligament; near its inferior extremity, it is confounded with the strong sae which joins the supercarpal bone to the first bone the inferior row and to the head of the external meta- carpal bone. b. The internal lateral ligament (Fig. 86, 4), analogous to the preceding and situated on the opposite side, is wider and thicker than it. It commences on the internal tube- rosity of the radius, and terminates on the upper extremity of the middle and internal metacarpal bones, after being attached, by two distinct fasciculi, to the third carpal bone of the upper row, and the two last of the metacarpal row. In contact by its external face with the tendon of the oblique extensor muscle of the metacarpus, this ligament responds, by its deep face, to the synovial membranes of the carpus and to the bones to which it is attached. By its anterior border it is united to the capsular ligament; the tet border is intimately confounded with the pos- terior ligament, from which it is impossible to distinguish it. e. The anterior, or capsular ligament, is 2 membranous band covering the anterior face of the carpal articulations. Its superior border is attached to the radius; the inferior is inserted into the superior extremity of the principal metacarpal bone. The two right and left borders are united with the lateral ligaments. Its external face is in contact with the tendons of the anterior extensor muscles of the metacarpus and phalanges. The internal face is lined at certain points by synovial membrane, and adheres in others to the carpal bones and the anterior ligaments binding these to one another. LATERAL VIEW OF THE CARPAL AR- TICULATIONS. 1, 1, Anterior liga- ments uniting the two rows of carpal bones; 2, 2, Anterior liga- ments proper to the carpo-meta- carpal articula- tion; 3, Common external _liga- ment; 4, One of the ligaments proper to the articulation of the two rows (metacarpo - su- pracarpal); 5, One of the liga- ments proper to the radio-carpal articulation (ra- dio - supracar- pal).—a, Groove on the external surface of the su- pracarpal bone for the passage of the external flexor of the me- tacarpus. This ligament is composed of transverse 152 THE ARTICULATIONS. fibres more or less oblique, and arranged crosswise; by its amplitude it can adapt itself to the movements of flexion of the knee. . - . d, The posterior ligament, one of the strongest in the animal economy, covers the posterior face of the carpus, filling up the asperities which roughen it. It is inserted: above, on the transverse crest surmounting the articular surface of the radius ; by its middle portion into all the carpal bones ; below, into the head of the principal metacarpal bone. Confounded inwardly with the internal lateral ligament, united outwardly to the band which attaches the supercarpal to the external metacarpal and the second carpal bone of the upper row, this ligament is continued, by its inferior extremity, with the carpal stay (or check ligament) which sustains the perforans tendon. Its posterior face is perfectly smooth, and is covered by the synovial membrane of the carpal sheath. Movements or THe Carpat ArticuLatTions.—The carpus is the seat of two very extensive and opposite movements—/lexion and extension ; to which are added three very limited accessory movements—adduction, abduction, and circumduction. All the carpal articulations do not take an equal part in the exeeu- tion of these movements; for it is easy to discover that they are chiefly — performed in the radio-carpal diarthrosis, and in the imperfect hinge articulation uniting the two rows of carpal bones. Each of these articula- tions participates in the movements of the carpus in nearly the same pro- portions, and both act in an identical manner. Their mechanism is most simple. In flexion, the first tier of bones rolls backwards on the radius, the inferior row moves in the same sense on the upper, the metacarpus is carried back- wards and upwards, the common posterior ligament is relaxed, the capsular ligament becomes tense, and the articular surfaces, particularly those of the second joint, separate from each other in front. In extension, the metacarpus is carried downwards and forwards by an inverse mechanism, This move- ment stops when the ray of the fore-arm and that of the metacarpus are in the same vertical line. In flexion, these rays never directly approach each other ; the inferior extremity of the metacarpus being always carried ou It may also be remarked, that the slight movements of abduction, adduction, and circumduction of the carpus are only possible at the moment when the foot is flexed on the fore-arm, : With regard to the planiform diarthrosis articulating the carpal bones of the same row, they only allow a simple gliding between the surfaces in contact ; and with the carpo-metacarpal arthrodia it is absolutely the same. The restricted mobility of these various articulations has but a very secondary influence on the general movements of the carpus; but it nevertheless fayours them by permitting the carpal bones to change their reciprocal relations, and adapt themselves, during the play of the radio-carpal and intercarpal hinges, to a more exact coaptation of the articular planes which they form. In the other animals, the carpal articulations have the same essential characteristics we have noticed in Solipeds. The four principal peripheral bands differ but little in them; though in the Dog and Cat they are lax enough to allow somewhat extensive lateral movements. 5. Intermetacarpal Articulations. Each lateral metacarpal bone articulates with the middle one by means of diarthrodial and synarthrodial surfaces, for the description of which refer to page 82. An interosseous ligament, composed of very short and strong i fis... ARTICULATIONS OF THE ANTERIOR LIMBS. 153 fasciculi, is interposed between the synarthrodial surfaces, and binds them firmly together. Its ossification is not rare. The diarthrodial facets are maintained in contact by the preceding ligament, and by the carpal ligaments inserted into the head of the lateral metacarpal bones. The intermetacarpal articulations only allow a very obscure, vertical, gliding movement. In the Oz, there is only one intermetacarpal articulation, which is much simpler than those in the Horse. ! ._ In the Pig, the four metacarpal bones correspond, at their upper extremity, by means of small diarthrodial facets on their sides. Fibrous fasciculi, derived from the great anterior and posterior ligaments of the carpus, protect these intermetaearpal articula- tions before and behind. Other fibres, situated between the adjacent faces of the , bones, are real interosseous ligaments. In the Dog and Cat, the four great metacarpal bones articulate with each other in almost the same manner as in the Pig, but their mobility is greater. 6. Metacarpo-phalangeal Articulation. Preparation.—T urn down the anterior and lateral extensor tendons of the phalanges of carefully cutting through their attachment with the capsular ligament. ter oan the aie sheath from aboye to below, and turn down the flexor This is a perfect hinge-joint, formed by the inferior extremity of the median metacarpal bone on the one part, and the superior extremity of the upper phalanx and sesamoids on the other. Articular surfaces.—For the metacarpal bone, there are two lateral condyles and a median antero-posterior eminence; for the first phalanx, two glenoid cavities and an intermediate groove prolonged posteriorly on the anterior face of the two sesamoids. Divided in this manner into three por- tions, the digital surface is well constituted for solidity, because the pressure transmitted to this region is diminished and diffused by the natural elasticity of the bands which unite these three pieces to each other, Mode of union. The means of union may be divided into two categories : 1, Those which join together the several bones of the inferior surface ; 2, Those which maintain in contact the two opposed articular surfaces. A. The first have received the generic name of sesamoid ligaments, and are six in number: an intersesamoid ligament, which keeps together the two complementary bones of the digital surface; three inferior and two lateral sesamoid ligaments, which unite these bones to the first phalanx. a. The intersesamoid ligament is composed of fibro-cartilaginous substance which appears to be the matrix in which the two sesamoids were developed, as it is spread around these bones, after being solidly fixed on their internal face. Behind, this ligament, in common with the posterior face of the sesa- moids, forms the channel (Fig. 89, 5) in which the flexor tendons glide. Tn front, it occupies the bottom of the intersesamoid articular groove. b. The inferior sesamoid ligaments, situated at the posterior face of the are distinguished as superficial, middle, and deep. superficial ligament (Fig. 89, 8), the longest of the three, is a narrow band flattened before and behind. It arises from the middle of the fibro- ilaginous mass which completes, posteriorly, the superior articular surface of the second phalanx, and slightly widening, ascends to the base of the sesamoids, into which it is inserted by becoming confounded with the intersesamoid ligament. Its posterior face, lined by the synovial membrane of the so-called sesamoid sheath, is covered by the flexor tendons; it partly covers the middle ligament. The middle ligament, triangular and radiating, is composed of three 154 THE ARTICULATIONS. particular fasciculi: two lateral (seen on each side of the superficial li ment in Fig. 89, 8), and a median which has been generally confoun with the superficial ligament, although it is clearly distinguished from it by its inferior insertion. Fixed in common to the posterior imprints of the first phalanx, these three fasciculi diverge in ascending to the base of the sesamoids, where they have their upper insertion. The deep ligament is constituted by two small bands concealed beneath the middle ligament. Thin, short, flattened before and behind, and inter- crossed, these bands are fixed to the base of the sesamoids in one direction, and in the other to the superior extremity of the first phalanx, near the margin of its articular surface. This ligament is lined on its anterior face by the synovial membrane of the articulation." c. The lateral sesamoid ligaments are two thin layers extending from the external face of each sesamoid to the tubercle of insertion on the side of the superior extremity of the first phalanx. They are covered by the digital vessels and nerves, by the fibrous stay detached from the sus i ment to the anterior extensor tendon of the phalanges, and by the superficial fasciculus of the lateral metacarpo-phalangeal ligament ; they are covered by synovial membrane on their internal face. B. The ligaments destined to unite the two articular surfaces of the meta- carpo-phalangeal joint are four: two lateral, one anterior, and one posterior. a. Each lateral ligament comprises two fasciculi, a superficial and a deep, firmly united by their adjacent faces. The superficial fasciculus commences on the button of the lateral metacarpal bone, attaches itself to the median metacarpal, and descends vertically to terminate at the superior extremity of the first phalanx. It covers the phalangeal insertion of the lateral sesamoid ligament and the deep fasciculus. The latter, attached superiorly in the lateral excavation of the inferior extremity of the principal metacarpal, radiates as it reaches the sesamoid and the superior extremity of the first phalanx, where it is fixed by mixing its fibres with’ those of the lateral sesamoid ligament. The inner face of this fasciculus is lined by the articular synovial membrane. ; b. The anterior ligament belongs to the class of capsular ligaments. It is a very resisting membraniform expansion which envelops the anterior face of the articulation. Attached by its upper border to the anterior margin of the metacarpal surface, and by its inferior border to the first phalanx, this expansion is confounded at its sides with the lateral ligaments. It is covered by the extensor tendons of the phalanges, which glide on its surface by means of small serous sacs. Its internal face adheres throughout its whole extent to the synovial capsule. c. The posterior ligament,? very approyiately named the suspensory ligament of the fetlock (Figs. 88 ; 89,4), is along and powerful brace, composed of white fibrous tissue, and often containing fasciculi of fleshy fibres in its texture. Lodged behind the median metacarpal, and between the two lateral meta- carpal bones, this brace is quite thin at its origin, but it soon becomes enlarged, and preserves its great thickness to the extent of its upper fourth. Examined in section, it appears to be formed of two superposed portions which are closely adherent to each other. The superficial portion, the thinnest, commences by three small branches, which are fixed to the first and second 1 The two bands described by Rigot as forming part of this ligament, belong to the lateral fasciculi of the middle ligament. 2 It corresponds to the two muscles which, in May, lie alongside the interosseous metacarpal muscles. See the Museles of the foot. ine ia -_ ARTICULATIONS OF THE ANTERIOR LIMBS. | 155 bones of the lower carpal row; the deep portion, much thicker, is attached to the ior face of the principal metacarpal for about 8-10ths of an inch. It has wrongly asserted that the suspensory ligament of the fetlock is continuous with the common posterior ligament of the carpus; it is, on the contrary, quite distinct from it. The carpal stay or deep palmar aponeu- rosis of Man, is alone in direct continuity with the common posterior liga- ment of the carpus. The suspensory ligament of the fetlock is bifid at its inferior extremity ; its two branches, after being fixed into the summits of the sesamoid bones, give origin to two fibrous bands which pass downwards and forwards to become united on each side to the anterior ex- tensor tendon of the phalanges. It is in relation, by its posterior face, with the perforans tendon and its carpal stay; by its anterior face, with the median metacarpal bone, and arteries and veins ; Fig. 88. nerves. ial membrane.—This membrane is pro- PAS ing cul-de-sac between the terminal branches of the preceding ligament. It is the distention of this sac which causes the articular swellings vulgarly designated ‘‘ windgalls.” Movements.—The metacarpo-phalangeal articu- lation permits the extension and flexion of the digit, and some slight lateral motion when the movable osseous ray is carried to the limits of flexion. SECTION OF THE INFERIOR In the Oz, Sheep, and Goat, this articulation consti- ROW OF CARPAL BONES, tutes a double hinge which resembles the simple gin- THE METACARPAL, AND THE glymus of monodactyles. SUSPENSORY LIGAMENT OF They have three intersesamoid ligaments: two lateral THE FETLOCK. to unite the large sesamoids of each digit, and a median 1, Os magnum; 2, Common which unites the internal sesamoids. e inferior sesa-- posterior ligament of the moidean ligamentous apparatus isfar from showing the same carpus; 3, Stay, or band degree of development as in the Horse; it is reduced for for the perforans tendon: each digit to four small bands, which remind one very 4, poe cas clout “or much of the deep li nt of the latter animal, as it has the fetlock; 5, Its super- been described by Rigot: two lateral bands pass directly ficial layer; 6, Its deep from the sesamoids to the upper ricer of the first fasciculus; 7, Principal phalanx; the other two, situated between the first, inter- metacarpal bone. cross and are confounded with the latter by their ex- tremities.—A lateral sesamoid ligament unites the first phalanx to the external sesamoid. For each digit there are two lateral metacarpo-phalangeal ligaments: an external, to that of the Horze, but less complicated, is attached rt its inferior extremity the first phalanx only; the other, internal, fixed superiorly in the bottom of the inter- articular notch of the metacarpal bone, is inserted into the inner face of the first —a in mixing its fibres with those of the superior interdigital ligament. This is situated between the two first phalanges, and is composed of short, intercrossed attached to the imprints which in part cover the internal face of the two first phalangeal bones. In the Sheep there are only traces of this interdigital ligament, and each internal metacarpo-phalangeal ligament gives rise, near its phalangeal insertion, to a fibrous branch which is directed backwards from the interdigital space, and is terminated in the bone of the ergot (or posterior rudimentary digit), which it sustains. The anterior or capsular ligament, single as in Solipeds, unites the two external lateral ligaments. The suspensory ligament, single superiorly, is divided inferiorly into eight " two of which are joined to the perforatus tendon to form with it the double ring through which the two branches of the perforans pass. Four other branches, in E ; s 156 pairs, extend to the summits of the sesamoids, That which is sent to each external sesamoid gives off, on the side of the first ‘a reinforcing band to the Fig. 89. POSTERIOR VIEW OF THE METACARPO- PHALANGEAL AND INTER - PHALAN- GEAL ARTICULA- ' TIONS ; RIGHT LIMB, 1, 3, Outer and inner _ rudimentary me- , tatarsal bones; 2, Perforans tendon THE ARTIOULATIONS. proper extensor of the digit. The two last, profound and median, descend into the interarticular noteh of the meta bone, after a single fasciculus; afterwards, they pass between the two al nee eee ligaments, and te from each other in — passing downw and forwards on the inner side of the first phalanx, to join the proper extensor tendon of each digit. : In the Pig, Dog, and Cat, for each metacarpo-phalangeal there is: a proper synovial membrane; an intersesamoid ligament; an inferior sesamoid ligament composed of two cross-bands; two small lateral sesamoid ligaments; two lateral metacarpo-phalangeal ments, attached inferiorly to the first phalanx and the sesamoids ; an anterior capsular ligament, in the centre of which is founda small bony nucleus, a kind of anterior sesamoid, over which glides one of the branches of the common extensor of the digits. The suspensory ligament is replaced by real palmar interosseous muscles see the Muscles of the fore-foot). Some fibres situated between the t phalanges of the great digits in the Pig, remind one of the superior interdigital ligament of the Ox. In Man, the cavity in the upper extremity of the first phalanx is completed by a glenoid ligament. . The glenoid ligaments of the four first digits are united to each other by a transverse .< of the metacarpus. The articulations are consolidated two lateral ligaments. The metacarpo-phalangeal articulations allow flexion and extension movements, as well as those of abduction and adduction ; but the latter are limited by the lateral ligaments. 7. Articulation of the First with the Second Phalanx, or « First Interphalangeal Articulation. (Preparation.—Remove the extensor tendon; throw oe the metacarpo-phalangeal sheath, and turn down the flexor tendons.) This is an imperfect hinge-joint, Articular surfaces.—On the inferior extremity of the first phalanx, there are two lateral condyles separated by a groove. On the superior surface of the second phalanx, there are two glenoid cavities and an antero-posterior ridge. ; 7 The latter surface is completed behind by a glenoidal — fibro-cartilage, very dense and thick, which also acts as a ligament. It is attached, in‘ one direction, to the second phalanx, between the superior articular surface and the kind of fixed sesamoid which margins it behind ; in the other, it is inserted into the first phalanx by means of six fibrous bands: two superior, which embrace the inferior, middle, and superficial sesamoid ligaments; two middle and two inferior, which extend to the sides of the inferior extremity of the first phalanx. This fibro-car- tilage is moulded, in front, to the articular surface of the — latter bone, and forms, by its posterior face, a gliding and its check ligament; 4, Suspensory ligament; 5, Gliding surface, or sheath for the flexor tendons, formed by the posterior face of the sesamoid bones, and intersesamoid, transverse, and annular ligaments; 6, Section of lateral sesamoid ligament; 7, Lateral fasciculus of the middle inferior sesamoid ligament; 8, Inferior superficial sesamoid ' ligament; 9, Lateral ligament of the first interphalangeal articulation; 10, Section of the terminal branch of the perforatus tendon; 11, Section of the lateral cartilage | of the foot; 12, Postero-inferior surface of navicular bone; 15, Section of lateral car- tilage, plantar cushion, and wing of pedal bone; 14, Perforatus tendon; 15, Perforans tendon, ARTICULATIONS OF THE ANTERIOR LIMBS. 157 surface for the perforans tendon (Fig. 89,5). It is confounded, laterally, with the two branches of the perforatus, and receives in the middle of its ior border the insertion of the inferior superficial sesamoid ligament. Mode of union.—Two lateral ligaments, to which are added, behind, the ’ i just described, and in front the tendon of the anterior extensor of the phalanges. These ligaments are large and thick, and passing obliquely downwards and backwards, are inserted, superiorly, into the lateral tubercles on the inferior extremity of the first phalanx. They are attached, beneath, to the sides of the second phalanx. Their most inferior fibres are even prolonged below that point to reach the extremities of the navicular bone, and constitute the posterior lateral ligaments of the pedal articulation. ___ Synovial membrane. This covers the tendon of the anterior extensor of the phalanges, the lateral ligaments, and the glenoid fibro-cartilage. Behind, it a cul-de-sac which extends between the latter and the posterior face of the first phalanx. Movements. This imperfect hinge is the seat of two principal movements: extension and flexion. It also allows the second phalanx to pivot on the first, and permits some lateral movements. In the Oz, , and Goat, the glenoid fibro-cartilage is confounded with the per- foratus tendon, and is only attached to the first phalanx by two lateral bands. The internal lateral ligament pores gs two fasciculi: one, very short, which terminates in the second yaar and another, very long, descending to the internal face of the third phalenx. e external is very thin, and is also prolonged to the terminal phalanx; so that the two last interphalangeal articulations of each digit are fixed by two common lateral ligaments which correspond exactly, by their position and inferior attachments, to the anterior Jateral ligaments of the pedal joint of Solipeds. In the Dog and Cat, the glenoid cartilage, also confounded by its posterior face with the — tendon, only adheres to the first phalanx by some cellular bands. The two lateral ligaments pass from the inferior extremity of the first phalanx to the superior extremity of the second. In the Pig, there is somewhat the same arrangement as in Carnivora. The external lateral ligament is, nevertheless, more like that of the Horse, in its most anterior fascieuli being prolonged to the external extremity of the navicular bone, 8. Articulation of the Second Phalanx with the Third, Second Interphalangeal F Articulation, or Articulation of the Foot. To form this imperfect hinge-joint, the second phalanx is opposed to the third, and to the navicular bone. Articular surfaces.—On the inferior face of the second phalanx there are two lateral condyles and a median groove. On the superior face of the third phalanx and the navicular bone, are two glenoid cavities separated by an antero-posterior ridge. The two bones which form this last surface arti- culate with each other by an arthrodia; the navicular bone presents for this purpose an elongated facet on its anterior border; the os pedis also offers an analogous facet on the posterior contour of the principal articular surface. Mode of union.—Five ligaments: a single interosseous one which joins _ the navicular to the pedal bone; and four lateral pairs, distinguished as anterior and posterior. a. Interosseous ligament.—This is formed of very short fibres which are inserted, behind, into the anterior groove of the navicular bone; and in front, into the posterior border and inferior face of the third phalanx. This ligament is lined, on its superior surface, by the synovial membrane, and on its inferior face is covered by the navicular sheath. b. Anterior lateral ligaments —These are two thick, short, and wide 158 THE ARTICULATIONS, fasciculi, attached by their superior extremities to the lateral imprints of the second phalanx, and by their inferior extrentities into the two cavities at the base of the pyramidal eminence of the os pedis. Each ligament is partly covered by the complementary fibro-cartilage of that bone, and appears to form a portion of it. Its anterior border is continuous with the common extensor tendon of the phalanges; its internal face is covered by the synovial membrane, which adheres closely to it. c. Posterior lateral ligaments—These have been already noticed. Each is composed of the lowermost fibres of the lateral ligament of the first interphalangeal articulation; these fibres, after being attached to the second phalanx, unite into a sensibly elastic fibrous cord, which is chiefly fixed into the extremity and superior border of the navicular bone, where the ligaments join each other, and in this way form a kind of complementary cushion which increases the navicular articular surface. It also sends off a short fasciculus to the retrossal process, and a small band to the internal face of the lateral fibro-cartilage. Partly concealed by the latter and the plantar cushion, this ligament is covered inwardly by the articular synovial membrane. J (For full details as to the manner in which the navicular is attached to ~ the pedal bone, the student is referred to the series of papers on the Horse’s Foot, published by me in the ‘ Veterinarian’ for 1870, It is only n to refer here to the intimate connection there exists between the lateral and interosseous ligaments, and the stratiform fibro-cartilage covering the pos- terior face of this sesamoid: a connection, or rather unification, which has been strangely overlooked by hippotomists and hippo-pathologists, but which has undoubtedly a most important bearing on the genesis of that most prevalent and formidable malady of the anterior foot of the Horse —navicularthritis.) Synovial membrane.—This descends below the facets which unite the navicular to the pedal bone. It offers, posteriorly, a vast cul-de-sac which reaches the posterior face of the second phalanx, and lies against the two navicular sheaths. It also forms another much smaller, by being prolo between the two lateral ligaments of the same side. This is very often dis- tended, and it is liable to be opened in the operation for diseased cartilages. Movements.—The same as those of the first interphalangeal articulation. In the Sheep are found: 1, An interosseous ligament to unite the navicular bone to , the third phalanx; 2, Two anterior lateral ligaments commencing, as already stated, at the first ESE ; 3, Two lateral posterior ligaments, passing to the posterior face of the second phalanx and the navicular bone (the internal is yellow and elastic); 4, A singl anterior, elastic ligament, attached above to, the superior extremity of the secon phalanx, end fixed below into the third, between the insertion of the common extensor of the digits and that of the internal anterior lateral ligament; an inferior interdigital ligament, situated between the ungueal phalanges, whose separation from each other it limits. This ligament is composed of parallel fibres, which extend transversely from the one navicular bone to the other, and is covered on its inferior face by the skin of the interdigital space. Its upper face is in contact with an adi cushion. In the Oz, the external anterior lateral ligament, wide and expanding, is almost — entirely covered by the long branch of the proper extensor of the digit, to which it is intimately adherent. The interdigital ligament has a much more complicated character _ | than that of the Sheep. It is formed of fibres intercrossed on the median line, and divided at its extremities into two fasciculi: a superior over the perforans tendon, ; to which it seryes as a restraining band, and is fixed to the outside of the inferior extremity of the first phalanx, after contracting very close adhesions with a strong fibrous web which descends from the posterior metaca region, and which will be more fully noticed when describing the muscles; an inferior, shorter than the preceding, attached to the internal extremity of the navieular bone and the internal face of the third phalanx, ARTICULATIONS OF THE POSTERIOR LIMBS. 159 becoming confounded with the perforans tendon, the plantar cushion, and the kera- mem 3 In the Pig, for the maintenance of the second interphalangeal articulation, there are: 1, Two lateral ligaments, carried from the lateral faces of the second phalanx to the external and internal faces of the third; 2, A third ligament, exactly resembling one of the posterior lateral ligaments of the pedal articulation of the Horse; this ligament Sareete from the inferior extremity of the first phalanx to the internal extremity of the navicular bone. Its analogue of the inner side appears to be altogether absent; but in the large digits there is an anterior yellow elastic ligament like that of Ruminants. _ Inthe Dog, the two last phalanges are united by two lateral ligaments, very simply arranged. A third ligament, formed of elastic tissue, divided into two lateral portions, and situated in front of the articulation, plays the part of a spring, which mechanically produces the retraction of the claw when the flexor muscles cease to contract. In the Cat, this yellow ligament is very strong; and this animal also exhibits a very striking ey of the articular pulleys by which the two phalanges correspond: an arrange- ment w its the claw to be lodged between two digits when they are raised, and thus fayour its retraction. The second interphalangeal articulation of the Dog and Cat is also distinguished another essential arrangement. The articular surface of the third phalanx is com- by a glenoid fibro-cartilage analogous to that of the first articulation, but much icker. This fibro-cartilage (see Muscites oF THE HAND) is fixed into the posterior rojection of the third phalanx, and serves, by its inferior face, as a pulley for the per- tendon and, with the projection just named, plays the part of the navicular bone in other animals, The interphalangeal articulations of Man are formed on the same plan as the metacarpo-phalangeal articulations. They are consolidated by a glenoid and lateral ligaments, and possess only the two movements of flexion and extension. Articte V.—ARTICULATIONS OF THE PostERIOR Luss. 1. Articulations of the Pelvis, (Preparation —These ligaments are all exposed to view by carefully removing the soft parts connected with the sacrum and cox.) A. Sacro-m1ac Arrticunation (Fig. 90).—This is a pair articulation which establishes the union of the posterior limb with the spine, and is formed by the sacrum and coxa. It belongs to the arthrodial class. Articular surfaces——On the sacrum, the irregular diarthrodial facet named the “auricular,” cut on the sides and near the base of the bone. For the coxa, the analogous facet on the internal face of the ilium. Mode of union.—By four ligaments, which, after the example of Rigot, we will name sacro-iliac, superior ilio-sacral, inferior ilio-sacral, and the a. Sacro-iliac ligament.—This is composed of thick fibrous fasciculi, which envelope the whole articulation in being firmly attached by their extremities to the imprints around the diarthrodial facets. The inferior moiety of this ligament is covered by the psoas-iliacus (iliacus) muscle. Its posterior half’ is much stronger, is hidden by the ilium, and gives attach- ment to the ilio-spinalis (longissimus dorsi) muscle. b. Superior ilio-sacral ligament.—A thick and short funicle which, rising from the internal angle of the ilium, is carried backwards to be fixed to the sacral spine, where its fibres are confounded with those of the super- spinous dorso-lumbar ligament. ¢. Inferior ilio-sacral ligament.—This is a very resisting, triangular, membranous band, formed of parallel fibres passing obliquely downwards and backwards. It is attached, by its anterior margin, to the upper half of * Tt re ts the interosseous sacro-iliac ligament of Man. ‘The inferior half corre- sponds to the anterior sacro-iliac ligament. 160 THE ARTICULATIONS. the ischiatic border and the internal angle of the ilium, in i confounded with the preceding ligament. Its inferior margin is into the rugged lip which borders the sacrum laterally. Its rocacala border is united to the aponeurosis covering the coceygeal muscles, and its external face is in contact with the principal gluteal and the long vastus muscles; while the internal corresponds to the lateral sacro-coccygeal muscle. ; d. Sacro-sciatic or ischiatic ligament (Fig. 90, 2).— this i is a vast mem- branous expansion situated on the side of the pelvis, between the sacrum and the coxa, and serves more as a means for inclosing this portion of the pelvic cavity than to assure the solidity of the sacro-iliac articulation, Its form is irregularly quadrilateral, and permits its cireumference to be divided into four borders: a superior, attached to the rugged lateral ridge of the sacrum; an inferior, fixed to the supercotyloid ridge, as well as the ischial tuberosity, and forming by the portion comprised between these two in- sertions, with the small ischiatic notch, the opening by which the internal obturator and pyramidal muscles leave the pelvis; an anterior, imperfectly limited, along with the great ischiatic notch, cireumscribes the opening through which the gluteal vessels and nerves, and the sciatic nerves pass; & posterior, doubled in the form of two laminw which embrace the semi- membranosus muscle, and is confounded superiorly with the aponeurosis enveloping the coccygeal muscles. The external face of this ligament is traversed by the sciatic nerves, and is covered by the long vastus and the semitendinosus muscles, which derive numerous insertions from it. Its internal face is covered, in front, by the peritoneum, and posteriorly is in contact with the ischio-coccygeal and ischio-anal muscles, to which it gives attachment. Synovial membrane.—This lines the sacro-iliac ligament, but only furnishes a small quantity of synovia. Movements.—The two sacro-iliac articulations being the centres towards which all the impulsive efforts communicated to the trunk by the posterior limbs converge, they do not offer much mobility, as that would oppose the integral transmission of the quantity of movement. So that they permit only a very restricted gliding of the articular surfaces; and the union of the sacrum and coxa by diarthrosis appears to be exclusively designed to prevent the fractures to which these bones would be incessantly exposed if they were fixed together in a more intimate manner. B. Articu.ation or tHe Two Coxa, or Iscaio-pusro Sympuysis.—The two cox are united to each other throughout the whole extent of the inner border of the pubis and the ischial bones. In youth, this is a veritable amphiarthrosis, fixed by an interosseous gartilage and bundles of peripheral fibres. The cartilage is solidly fixed to the small rugged eminences which cover the adjacent articular surfaces, and becomes ossified, like the sutural cartilages, as the animal advances in age. In adult Solipeds the cox are always fused with each other. The peripheral fibrous fasciculi extend tranversely from one bone to the other, above and below the symphysis; those on the inferior face are incomparably stronger and more abundant than the others. The movements of this articulation are most restricted, and depend solely upon the elasticity of the interosseous cartilage. They cease after its ossification. The fusion of the two coxe proceeds very slowly in the female of the Cat, Dog, Pig, Ox, Sheep, and Goat species. as te le Tk ie ARTICULATIONS OF THE. POSTERIOR LIMBS, 161 2. Coxo-femoral Articulation. (Preparation—Remove the muscles surrounding the articulation. To view the interior, divide the capsular ligament by a circular incision.) This is an enarthrosis, formed by the reception of the head of the femur into the cotyloid cavity of the coxa. Articular surfaces.—As already shown, the cotyloid cavity represents the segment of a hollow sphere, deeply notched on the inner side, and Fig. 90. SACRO-ILIAC AND COXO-FEMORAL ARTICULATIONS, WITH THE SMALL DEEP MUSCLES SURROUNDING THE LATTER. 1, Sacro-iliac ligament; 2, Sacro-ischiatic ligament; 3, Great ischiatic notch; 4, Anterior portion of the capsular ligament of the. coxo-femoral articulation; 5, Internal band of cotyloid ligament; 6, Coxo-femoral ligament ; 7, Pubio-femoral ligament; 8, Its insertion into the femur; 9, Small gluteal muscle; 10, Origin of the straight anterior muscle of the thigh (rectus); 11, Anterior thin muscle (rectus parvus); 12, Pyramidal muscle of the pelvis; 13, External obturator muscle; 14, Square crural muscle (quadratus femoris); 15, Inferior sacro- coccygeal muscle. vided at the bottom with a wide depression, the internal moiety of which is destined for the insertion of one of the interosseous ligaments, while the external half plays the part of a synovial fossa. This depression is not covered by cartilage, and communicates by the internal notch with the inferior furrow on the pubis. The lip of the cotyloid cavity is covered by a complementary fibro-cartilage—the cotyloid ligament. This fibro-cartilage is not interrupted at the notch just mentioned, but passes over it, forming a remarkable band (Fig. 90, 5) that converts it into a foramen, through which pass the pubio- or ilio-femoral ligament and the vessels of the articulation. M 162 ; THE ARTICULATIONS. Fixed by its adherent border to the margin of the cotyloid cavity, this ligament is lined by synovial membrane on its faces and free border. It is > . thickest in front and within. With re to the head of the femur, it will be remembered that it is exactly moulded to the cavity, and, like it, is excavated by a rugged fossa which is entirely oceupied by the insertion of the interarticular ligaments. Mode of union.—This joint is maintained by a peripheral capsule, and by two interarticular bands constituting the coxo-femoral and pubio-femoral ligaments. ok Capsular ligament (Fig 90, 4).—This is a membranous sac, like that of the scapulo-humeral articulation, embracing the head of the femur by its inferior opening, and attached by its opposite aperture to the margin of the cotyloid cavity and its protecting fibro-cartilage. This ligament is com- posed of intercrossed fibres, and is strengthened in front by an oblique fasciculus which descends to the body of the femur, along with the anterior thin muscle, near which it is fixed. Its internal face is covered by the articular synovial membrane, and its external face is in contact, through the medium of adipose cushions, with: in front, the anterior thin muscle (erwreus) and the straight muscle (rectus) of the thigh ; behind, to the gemini, the internal ~ obturator, and the pyramidal muscles; outwards and upwards, to the small gluteal muscle ; within and below, to the external obturator. b. Coxo-femoral ligament (ligamentum teres, Fig. 90, 6).—A thick and short funicle of a triangular shape, deeply situated between the two bony surfaces, which it cannot, notwithstanding its shortness, maintain exactly in contact without the other muscular or ligamentous structures enveloping the articulation. Its upper insertion occupies the internal moiety of the bottom of the cotyloid cavity; and its inferior extremity is confounded with the pubio-femoral ligament, being fixed with it into the rough fossa in the head of the femur. =I‘ is enveloped by the synovial membrane. c. Pubio-femoral ligament (Fig. 90, 7, 8).—This ligament, longer and stronger than the last, originates from the pubic tendon of the abdominal muscles and the anterior border of the pubis. Lodged in the inferior channel of that bone, it passes outwards, enters the internal notch of the cotyloid cavity, is inflected downwards on the fibrous band which converts that notch into a foramen, and goes with the preceding ligament to be inserted into the fossa in the head of the femur. Its pubic portion lies between the two branches of the pectineus, while its interarticular surface is covered by synovial membrane. , novial membrane.—This membrane is very extensive; it lines the internal face of the capsular and cotyloid ligaments, and is reflected on the interarticular ligaments to form around them a serous vaginal covering. It is even prolonged into the synovial fossa occupying the centre of the cotyloid cavity. Movements.—The coxo-femoral articulation is one of the joints which is endowed with the most varied and extensive movements. It permits the flexion, extension, abduction, adduction, circumduction, and rotation of the thigh on the pelvis. The mechanism of these movements is so simple, that they need no particular consideration, The domesticated animals other than Solipeds, are distinguished by the complete absence of the pubio-femoral ligament; so that in them the movements of abduction, which are limited in Soli by the tension of this ligament, are much more extensive; and it is the absence of the ligament in question, which explains the facility with which the larger Ruminants are enabled to strike sideways, a movement known as a “ cow’s kick,” ; 7 « _ = c ARTICULATIONS OF THE POSTERIOR LIMBS. 163 In Man, the head of the femur is more detached than in the domesticated animals, and the cotyloid cavity, encircled by the cotyloid ligament, is deeper. The femur is united to the coxa: 1, By a capsular ligament ; 2, By a triangular ligament, fixed above, to the cotyloid ligament at the notch, and below, into the depression in the head of the femur. Also, as the brothers Weber have shown, the atmospheric pressure is a powerful adjunct to these means of union. The coxo-femoral articulation of Man permits more extensive movements than that of animals, and especially abduction and adduction, which can be carried to 90 degrees. 3. Femoro-tibial Articulation. ’ ion.—Remove the soft parts surrounding the articulation, taking care not to - wound the synovial membrane. ‘To expose the crucial ligaments, make an antero- posterior vertical section of the femur in such a way as to separate the condyles.) This is the most complicated joint in the body, and is formed by the union of the femur with two of the thigh bones—the tibia and patella. It represents an imperfgct hinge-joint. Articular surfaces.—To form this articulation, the femur opposes its two condyles to the wide, convex, and undulated facets on the superior face of the lateral tuberosities of the tibia, and its articular pulley to the posterior face of the patella. : The femoral faces have already been described in detail at page 98; but it may be repeated that the two condyles, placed side by side, are elongated in an antero-posterior direction, and are separated by a non-articular notch _ ealled the intercondyloid ; also, that the femoral trochlea situated in front of these two condyles appears to continue the preceding notch, and that its internal border is much more elevated than the external; an arrangement which explains why it is so difficult, if not impossible, for the patella to be dislocated inwards. The tibial facets ascend on each side to the lateral faces of the tibial spine. They are separated from one another by the antero-posterior groove cut on the summit of that bone, and by the fosse of insertion situated at its base before and behind. The external facet, wider than the internal, is devoted in part to the gliding of the originating tendon of the popliteal muscle. (See page 100.) The patellar surface, moulded on the femoral pulley, fits it in an imper- fect manner. It is bordered, outwardly, by a small fibro-cartilaginous ring, which is united to the fibrous capsule of the femoro-patellar articulation (Fig. 92,1). Inwardly, it is completed by the insertion of the internal patellar ligament, to be noticed immediately. Interarticular meniscii (semilunar fibro-cartilages)—(Figs. 91, No. 1, 2, 3, 4; and 92, 5, 6,7, 8).—By this designation is known the two fibro- cartilages interposed between the condyles of the femur and the tibial facets, to assure their coaptation. They are crescent-shaped bodies, and present : an internal, concave, thin and sharp border, embracing the tibial spine; an external, thick, and convex border ; a superior face, excavated and moulded to one of the condyles ; an inferior face, nearly plane, gliding on the tibia; and two extremities terminated by ligaments, and fixed to the bones in apposition. The articular surfaces are not entirely separated throughout their extent by ? By this name is understood the joint uniting the femur to the tibia, and that which articulates it with the patella. Following the example of anthropotomists, it has no been deemed necessary to describe a femoro-patellar articulation distinct from the femory-tibial, properly so called. This innovation appears to be justified by the com- mounity of cos presen articular bands which bind these two joints, and by the reciprocal dependence of their movements. 9 M 164 THE ARTICULATIONS. ——~~—these complementary meniscii, for the tibial spine rubs directly against the inner sides of the femoral condyles. The internal semilunar fibro-cartilage, the widest and thickest, is inserted by its anterior extremity into one of the excavations situated in front of the spine; its posterior extremity is attached in the fossa behind that eminence. The eaternal semilunar fibro-cartilage is fixed, in front, near the anterior insertion of the opposite fibro-cartilage ; its posterior extremity gives origin to two slips or cords, one superior, the other inferior. The first, the strongest and longest, terminates in the fossa near the posterior extremity of the intercondyloid notch. The second, thin and flat, is inserted on the posterior outline of the external tibial facet. Fig. 91. No, 1. FEMORO-TIBIAL ARTICULATION. No. 1. Posterior face: the posterior ligament has been removed.—1, External menis- cus; 2, Fibrous fasciculi fixing it to the femur; 3, Fibrous fascia which attaches it to the posterior contour of the tibial surface; 4, Internal meniscus; 5, Tibial insertion of the posterior crucial ligament; 6, External lateral ligament; 7, Internal lateral ligament. No. 2. External face: the external condyle of the femur and the meniscus have been removed to show the crucial ligaments.—J, Anterior crucial ligament ; 2, Posterior ditto ; 3, Fibular insertion of the external lateral ligament; 4, Anterior patellar ligaments.—a, Internal meniscus; B, Anterior insertion of the external meniscus ; c, Passage for the tendinous cord common to the flexor of the metatarsus and the anterior extensor of the phalanges; D, Anterior and superior tuberosity of the tibia; x, Tibial crest. The external border of this meniscus is separated from the external lateral ligament by the tendon of the popliteus muscle, and acts, with regard to this tendon, as a pulley. Mode of wnion.—The bands which bind this complicated articulation are very numerous. They will be successively described as: 1, Those which attach the patella to the tibia ; 2, Those which unite the femur with the tibia, A. Ligaments attaching the patella to the tibia.—The patella is bound to the tibia by three funicular ligaments, designated by the generic epithet of “patellar.” They are situated in front of the articulation, and are charged ARTICULATIONS OF THE POSTERIOR LIMBS. 165 with the duty of transmitting to the leg the action of the muscles which ure attached to the patella. They are distinguished according to their position, as external, internal, and middle. (Fig. 92, 2, 3, 4.) a. The external patellar ligament, the largest and most powerful, is a flattened band, attached, by its lower extremity, to the culminating point of the anterior tuberosity of the tibia. Its upper extremity is fixed to the anterior face of the patella, and is confounded with the patellar insertion of the long vastus muscle. It is joined to the internal ligament by a very isting aponeurotic expansion, a dependency of the fascia lata. b. The internal patellar ligament also forms a flattened band, longer, but not so wide or thick as the preceding. Its inferior extremity is attached to the inner side of the anterior tuberosity of the tibia. Its superior extremity becomes much thickened and fibro-cartilaginous, and is inserted into a inence inside the patella. This fibro-cartilaginous portion (Fig. 92, 3’ of the ligament glides on the internal border of the femoral trochlea, an may justly be considered as a complementary apparatus of the patellar surface. The ligament, joined to the preceding by the fibrous fascia already mentioned, is mixed up, inwardly, with the aponeurosis of the adductor muscles of the leg. e. The middle patellar ligament is a round cord, situated, as its name indicates, between the other two, concealed beneath the aponeurosis which unites these, and in the middle of the adipose tissue protecting the synovial capsules in front. Itleaves the anterior face of the patella, and descends vertically to the tibia, to be lodged in the fossa in the middle of the anterior tuberosity, where a small synovial bursa facilitates its movements. Its inferior extremity is inserted into the most declivitous part of this excavation. : B. Ligaments which attach the thigh and leg bones.—These are six in number: 1, A femoro-patellar capsule maintaining the patella against the femoral trochlea ; 2, Five femoro-tibial ligaments, as follows: two lateral, two external and internal; a posterior; and two interarticular, distinguished with reference to their inferior insertion into anterior and posterior. a. The femoro-patellar capsule is a membranous expansion which covers, above and laterally, the superior synovial membrane. This capsule is attached by its borders around the femoral trochlea and the periphery of the llar surface. It is extremely thin in its superior part ; but laterally it is thicker, and constitutes two wide fibrous fasciculi which bind the patella to the eccentric sides of the two condyles, and is described in several works as two special ligaments. Its external face is covered by the insertion of the vastus and the crural triceps. b. The lateral ligaments are two ribbon-shaped cords situated at the extremities of the transversal axis of the articulation, more behind than before ; they are relaxed during flexion, and very tense in extension. The external, the shortest and strongest, proceeds from one of the hollow facets on the external condyle of the femur, and is inserted into the head of the fibula by its inferior extremity, after gliding over the external tuberosity of the tibia by means of a special synovial bursa. It is covered by the erural or tibial aponeurosis, and covers the tendon of the popliteus, from which it is sometimes separated by a vesicular synovial membrane. The internal is attached, superiorly, to the eminence of insertion that surmounts the eccentric face of the internal condyle, and descends vertically to the tibia, gliding over the margin of its articular surface by means of a small facet covered with cartilage, and a cul-de-sac prolongation of the rf i * 3 166 THE ARTICULATIONS. internal synovial membrane. It is fixed by its inferior extremity to the imprints which cover the internal tibial tuberosity. Its fibres are disposed in two layers, which slightly intercross in X fashion ; those passing downwards and forwards adhere to the border of the internal meniscus. Covered by the aponeurosis of the adductor muscles of the leg, this ligament adheres by its deep face to the internal meniscus. c. The posterior ligament belongs to the class of membranous or capsular ligaments. It is formed of two aponeurotic laminw separated superiorly, but confounded inferiorly. The superficial lamina is composed of s > fibrous, intercrossed fasciculi, perforated with vascular openings. It hep. above, to the posterior face of the femur, below the external gastrocnemius muscle. The deep lamina envelopes, like a cap, the femoral condyles. After becoming united, these two laminew are attached to the posterior face of the tibia, close to the superior articular face of that bone. Its external face is in contact with the popliteal vessels, and the external gastrocnemius muscle. Its internal face is covered throughout nearly the whole of its extent by the lateral synovial membranes, embraces the condyles of the femur, and adheres to the posterior crucial ligament, as well as to the interarticular meniscii. son d, The interosseous ligaments are two funicular bands lodged in the inter- condyloid notch. They are more commonly designated crucial ligaments, because they cross each other at their middle part, like the letter X. Fig. 91. The eae oblique downwards and forwards, is attached by its superior extremity to the bottom of the intercondyloid notch, and inwardly to the external condyle. Its inferior extremity is fixed in the groove on the summit of the tibial spine. The fibres entering into its formation are not parallel, but slightly twisted in a spiral manner. The posterior, longer than the preceding, and oblique in the opposite direction, is inserted, inferiorly, into the little eminence behind the internal tibial facet ; whence it goes to the bottom of the intercondyloid notch, to be attached by its superior extremity within the internal condyle. Synovial membranes.—F or this articulation there are three synovial membranes: a superior and two lateral. The first, very large and sustained by the femoro-patellar capsule, facilitates the gliding of the patella on the femoral pulley; it is prolonged in a cul-de-sac below the insertion of the crural triceps. The other two, which lubricate the articular surfaces of the proper femoro-tibial joint, include the crucial ligaments between them, and cover the posterior ligament, the lateral ligaments, and the fibrous fasciculi for the attachment of the meniscii. The external covers, in addition, the tendon of the popliteus muscle, and furnishes a vast cul-de-sac which descends in the anterior groove of the tibia to envelop the tendon common to the anterior extensor of the phalanges and the flexor of the metatarsus. These two femoro-tibial synovial membranes lie against that of the femoro-patellar articulation, in front of the condyles and the notch which separates them, and if not always, at least not unfrequently, they communicate with it. The three are separated from the ligaments of the patella by a considerable mass of adipose tissue which is prolonged into the intercondyloid notch, at the bottom of which it appears to be fixed. Movements.—This imperfect hinge joint can execute the two principal and opposite movements of flexion and extension, and a somewhat limited acces- sory movement of rotation. The mechanism of these movements being simple enough to be readily understood without any preliminary explanation, ARTICULATIONS OF THE POSTERIOR LIMBS. 167 they will not be detailed here; but some remarks will be made with regard to the displacement the fibro-cartilages undergo when the articulation is in motion. During flexion and extension, these bodies, fixed on the tibial facets, which _ they transform into glenoid cavities, move with them on the condyles of the femur, from before to behind, or behind to before, according to the movement executed. But at the same time they also glide in an inverse direction, and to a very appreciable degree, on the superior extremity of the tibia. There- fore, during flexion, they pass from behind forward on this extremity, and are drawn backwards during exten- sion. In rotation, which may take place from within to without, or from with- out to within, the movement is pro- duced not only by the pivoting of the condyles in their glenoid cavities, but also by a sensible displacement of the meniscii on the tibial surfaces. In the Dog and Cat, the meniscii are together near their anterior insertion a transverse fibrous band. There is only one patellar ligament, and the posterior liga- ment shows in its thickness two small sesa- moid bones against which the condyles of the femur play inwardly, and which give ent, outwardly, to the originating branches of the external gastrocnemius mus- cle. There is no femoro-patellar capsule, and only one synovial membrane for the whole articulation. In the Pig and Sheep, there is also only one ligament and one synovial capsule. 4. Tibio-fibular Articulation. This articulation represents a small planiform diarthrosis, whose move- ments are very limited and obscure. It is formed by the union of the irre- diarthrodial facet which occupies the internal face of the head of the fibula, with the analogous facet on the external superior tuberosity of the tibia. Short and strong interosseous or peripheral fibres envelop these facets on every side, and maintain them firmly in contact. Fig. 92. LIGAMENTS ATTACHING THE THREE BONES OF THE LEG, No, 1. Posterior face.—No, 2. Anterior face. —1, Complementary fibro-cartilaginous of the patellar surface; 2, External patellar ligament ; 2’, Insertion of the long vastus into this ligament; 3, Internal patellar ligament; 3’, Its upper insertion transformed into a complementary appa- ratus of the patellar surface; 4, Middle patellar ligament; 5, External meniscus of the tibia; 6, Its branch of insertion into the femur cut off at its origin: 7, Its posterior tibial insertion; 8, External me- niscus; 9, Insertion of the anterior crucial ligament into the fossa of the tibial spine ; 10, Tibial insertion of the posterior crucial ligament; 11, Inferior insertion of the ex- ternal femoro-tibial ligament; 12,13, 14, Tibio-fibular ligaments.—a, Tibial arch ; B, Surface of insertion of the popliteus muscle; ©, Surface of insertion for the perforans muscle. The fibula is also attached to the tibia: “1, Above, by two small liga- mentous fasciculi crossed like the letter X, which form the superior part of the great arch through which pass the anterior tibial artery and vein (Fig. 92, 12); 2, In the middle, by a kind of aponeurotic membrane, whose width 168 THE ARTICULATIONS. diminishes from above to below, like that of the space it fills (Fig. 92,13); 3, Below, by a ligamentous cord (Fig. 92, 14) which prolongs the fibula to the external tuberosity of the inferior extremity of the tibia, where this cord bifureates, and is united to the two external lateral ligaments of the tibio- tarsal articulation.” —Rigot. In the Ox, Sheep, and Goat, the fibula being replaced by a ligament, there is no proper tibio-fibular articulation. In the Dog and Cat, the two principal bones of the leg are united at their extremities and middle part: 1, At their superior extremity, by means of a small arthrodial articulation, analogous to that of the Horse, and, like it, provided with a particular synovial bursa ; 2. At their inferior extremity, by means of a second arthrodial articulation, whose action is facilitated by a prolongation of the tibio-tarsal synovial membrane ; 3. By their middle part, through the interposition, between the two bones, of an interosseous ligament, which is wide and membranous in its upper two-thirds, and formed of extremely short and strong fibres at its lower third. : In the Pig, the arrangement is somewhat the same as in Carnivora, It may be noted, however, that the facet of the upper extremity of the fibula is joined to the tibia by a small interosseous ligament, and that the articulation which results should be looked upon as a small amphiarthrosis, In Man, as in the Dog there are two peroneo-tibial arthrodiz : a superior and inferior. _ 5. Articulations of the Tarsus or Hock. (Preparation.—Remove the tendons from around the articulation, and incise, layer after layer, the superficial fibres of the lateral ligaments.) These comprise: 1, The tibio-tarsal articulation; 2, The articulation of the first row of bones—the astragalus and calcis; 3, Those which unite the bones of the lower row; 4, The articulation of the two rows with each other ; 5, The tarso-metatarsal articulation. The first is a perfect gingly- moid, and the only joint really movable; all the others are arthrodial, and their action is so restricted that they appear to be condemned to almost absolute immobility. This intimate union of the tarsal and metatarsal bones is evidently chiefly intended to guarantee precision in the movements of the tibio-tarsal articulation. Trp10-TaRSAL ARTICULATION.—T wo bones alone concur in the formation of this angular ginglymoid joint : these are the tibia and astragalus. Articular surfaces.—For the tibia: 1, The two deep grooves, oblique forwards and outwards, channeled in the inferior extremity of the bone; 2, The salient tenon which separates these grooves, and on which there is often a small synovial fossette.—For the astragalus, the pulley occupying its anterior face (see page 103). j Mode of union.—Seven ligaments bind these articulations: two external lateral, three internal lateral, an anterior and a posterior. a. External lateral ligaments.—These are distinguished, according to their relative position, into superficial and deep. The external superficial ligament (Figs. 93, 2; 94, 2), is a thick funicular cord, flattened in its inferior half. It commences above on the external tuberosity of the tibia, behind the groove which divides this tube- rosity into two parts; from thence it descends almost vertically, fixing itself successively to the astragalus, caleaneus, cuboides, middle metatarsal bone, and the external rudimentary metatarsal bone. Passing in front with, and partly covered by, the lateral extensor of the phalanges, to which it supplies a retaining band (Fig. 94, 2), this ligament is confounded behind, and near its inferior extremity, with the calcaneo-metatarsal ligament. It external calcanco-astragaloi ing, is attached, superiorly, to the anterior part _of the external tuberosity of the tibia, and is directed obliquely backwards and downwards, to be fixed by two fasciculi at the external side of the astragalus and calcis. This ligament, covered by the preceding, which crosses it like an X, is lined on its inner face by the synovial membrane of the articulation. b. Internal lateral ligaments.—These are also three funicular bands superposed on one another, and are consequently designated as superficial, middle, and The internal su, ial ligament (Fig. 93, 6), the and longest of the three, proceeds from the internal and inferior tuberosity of the tibia, diminishing as it descends on the inner side of the tarsus. It is fixed, in mixing with the astragalo- metatarsal ligament and with the posterior tarso- metatarsal ligamentous arrangement, to the tuberosity of the astragalus, the scaphoid, the two cuneiform, the superior extremity of the principal metatarsal, and that of the internal rudimentary metatarsal bones. The internal middle ligament (Fig. 93, 5) is com- posed of two funicular cords, attached in common beneath the preceding ligament to the internal tibial tuberosity. These two fasciculi, exactly resembling those of the external deep ligament, are directed downward and backward, and terminate, one at the astragalus, the other at the calcis. The internal deep ligament (Fig. 93, 4) is an ex- tremely slender fasciculus, enveloped by the synovial membrane; it is often reduced to a thin shred, searcely distinct from the serous covering surround- ing it. It is attached, in one direction, to the tibia w the middle ligament; in the other to the astragalus, and nearly at the same point as the superior fasciculus of the middle ligament. ARTICULATIONS OF THE POSTERIOR LIMBS. covers the external and oe ligament, the short band which constitutes the ligament, the insertion of one of the branches _ of the flexor of the metatarsus, and the small cuboido-cunean (cuneiform) 169 t. The external deep ligament (Figs. 93; 94, 1), much shorter than the Fig. 93. TARSAL ARTICULATIONS 5 FRONT VIEW. 1, External deep ligament of the tibio-tarsal ar- ticulation; 2, 2, Ex- ternal superficial liga- ment; 4, Internal deep ligament; 5, Internal middle ligament ; 6, In- ternal superficial liga- ment; 7, Astragalo- metatarsal ligament ; 8, Small cuboido-cunean ligament.—a, Pulley of the astragalus; B, Cu- boidal insertion belong- ing tothe tendinous cord of the flexor of the me- tatarsus; ©, Vascular canal of the tarsus. ec. Anterior ligament.—This is a membraniform band formed of inter- crossed fibres, stronger outwards than inwards, attached by its upper border above and in front of the tibial surface, fixed by its inferior border to the astragalus, the scaphoid and great cuneiform bones, and the astragalo- _ metatarsal ligament; it is confounded at its sides with the two superficial lateral ligaments. Its internal face is lined by articular synovial mem- brane, while the external is covered by the flexor of the metatarsus, the anterior extensor of the phalanges, the anterior tibial artery, and several large anastomosing veins from whose junction arises the anterior tibial d. Posterior ligament.—This is the second membraniform or capsular band which protects the articulation posteriorly. It presents, in its centre, 170 THE ARTICULATIONS. a fibro-cartilaginous thickening, on which glides the perforans tendon. It is attached, above, to the tibia, below, to the astragalus and calcis; at its sides it is mixed with the two superficial lateral ligaments, and the i fasciculus of the middle internal ligament. Its internal face is lined by articular synovial membrane ; the external is covered and lubricated by the vaginal serous membrane which facilitates the gliding of the perforans tendon in the tarsal sheath. Synovial membrane.—This membrane is developed at the internal face of the two capsular ligaments, nearly covers the three internal ligaments, and lines the external deep ligament. It communicates, in front and below, with the synovial membrane proper to the articulation of the two rows of tarsal bones. When it becomes the seat of dropsical effusion, it is always distended forwards and inwards, because it is only sustained at that place by the anterior capsular ligament. But the effusion may also raise the posterior ligament and produce hernia in the hollow of the hock, behind the lateral ligaments. It is not, therefore, absolutely correct to attribute all the synovial tumours in the hollow of the hock to dilatation of the tarsal tendinous sheath. sé Movements.—Nothing can be less complicated than the mechanism of the tibio-tarsal articulation ; this joint only permitting two opposite movements, those of flexion and extension, which are so simple and precise that we may dispense with a description of the manner in which they are executed. It may only be remarked that, in order to prevent contact between the leg and foot during flexion, the latter fraction of the limb deviates a little outwards, owing to the marked obliquity of the articular grooves. : ARTICULATION OF THE Bones or THE First Row, orn CALCANEO- ASTRAGALOID ARTIOULATION.—This is a compound arthrodial joint, resulting from the coaptation of the three or four articular facets of the posterior face of the astragalus with the analogous facets of the calcis, This joint is maintained by the lateral ligaments of the tibio-tarsal articulation, and by four calcaneo-astragaloid ligaments—a superior, external, internal, and the last interosseous. The superior calcaneo-astragaloid ligament is formed of short parallel fibres thrown across from one bone to the other, and is situated towards the superior extremity of the pulley of the astragalus; it is lined superiorly by the synovial membrane of the tibio-tarsal articulation. The lateral ligaments are two very thin fasciculi concealed by the ligaments which bind, laterally, the tibia to the tarsal bone. The interosseous ligament is very strong, and occupies a great portion of the rugged excavation which separates the articular facets. This articulation does not usually possess proper synovial capsules. Two prolongations of the synovial membrane of the two rows, in ascending between the calcis and astragalus, facilitate the gliding of the two inferior facets. An analogous prolongation of the tibio-tarsal synovial membrane is- effected for the superior facets, and it is not rare to find this prolongation form a distinct capsule. ; Movements nearly null. ARTICULATION OF THE Bonzs ofr THE Second Row wIitH EACH OTHER.— These bones, four in number, are brought into contact in the following manner :—The cuboides responds to the scaphoid by two facets, one anterior, the other posterior; it articulates with the great cuneiform by two similar facets, the posterior of which is not always present. The scaphoid is united to the two cuneiforms by the large convex facet occupying its entire lower y _ are somewhat numerous. They are as follows: ek. The to the articulations of the second row of bones. and to the great cuneiform bone, one above, the other below the vascular channel formed between these three bones. 8. Two interosseous ligaments analogous to the ing two, forming the superior and inferior walls of the aforesaid channel. 4. An interosseous scaphoido-cunean liga- ment, passing from the scaphoid to the two i bones. 5. An interosseous ligament, named the i is directed from one cuneiform bone to the other, and is confounded with the preceding ligament. The disposition of the lubricating mem- branes varies with that of the articular facets. The following is what is most generally obseryed :—A- proper synovial membrane is specially destined for the facets by which the scaphoid and great cuneiform bones correspond ; this ial membrane belongs also to the two euboi phoid and posterior cuboido-cunean arthrodiw. The anterior cuboido-scaphoid diar- throsis receives a prolongation from the syno- vial membrane of the two rows. The play of the anterior cuboido-cunean and intercunean facets is facilitated by two prolongations of the tarso-metatarsal synovial membrane. Movements almost null. ARTICULATION OF THE Two Rows WITH EACH orner.—This arthrodial joint is formed by the union of the calcis and the astragalus, on the one side, with the scaphoid and cuboid bones on the other. Its solidity is assured by six principal bands : 1. The two lateral superficial ligaments of _ the tibio-tarsal articulation. 2. The calcaneo-metatarsal ligament (Fig. 94, 3), a strong fibrous brace which unites the ARTICULATIONS OF THE POSTERIOR LIMBS. 171 face. The two cuneiforms are joined by means of a small articular The fibrous fasciculi which maintain the diarthrodial surfaces in contact q astragalo-metatarsal ligament and tarso-metatarsal apparatus, which will be described hereafter; these two bands do not properly belong ’ 2. Two anterior ligaments, named euboido-scaphoid and cuboido-cunean (Pigs. 93,8; 94, 5), which are carried from the cuboid to the scaphoid Fig. 94. ARTICULATIONS OF THE TARSUS; LATERAL VIEW. 1, External deep ligament; 2, External superficial ligament ; 2’, Ring furnished by the latter ligament for the passage of the lateral extensor tendon of the phalanges; 3, Calcaneo-meta- tarsal ligament; 4, Astragalo- metatarsal ligament; 5, Small cuboido-cunean ligament.—a, Cuboidal insertion of the flexor muscle of the metatarsus; B, Anterior orifice of the vascular conduit of the tarsus ; c, Groove on the external tuberosity of the tibia for the gliding of the lateral extensor of the pha- langes ; D, Insertion of the gas-* trocnemius tendon of the leg into the os caleis; B, Gliding surface for that tendon. posterior border of the calcis to the cuboides, and to the head of the external rudimentary metatarsal bone. It is confounded, outwardly, with the external and superficial tibio-tarsal ligament; inwardly, with the posterior tarso- _ metatarsal band. 3. The astragalo-metatarsal ligament (Fig. 93, 7), a radiating fasciculus whose fibres leaye the internal tuberosity of the astragalus, become mixed 172 THE ARTICULATIONS. up with the internal and superficial tibio-tarsal ligaments in diverging down- pas wards to the scaphoides, the great cuneiform bone, and the upper extremity of the principal metatarsal bone. ae 4. The posterior tarso-metatarsal ligament is a vast, very strong, and ver, complicated fibrous arrangement, which binds, posteriorly, all the bones, and also fixes them to the three portions of the metatarsus. This band, which is crossed by several tendons and by the artery and vein lodged _ in the cuboido-scaphoido-cunean canal, is continued below by the tarsal stay of the perforans tendon. It therefore closely resembles the posterior = carpal ligament. Its posterior face is covered by the tendinous synovial — membrane lining the tarsal sheath for the passage of Deon er tendons. It is confounded, on its sides, with the calcaneo-meta and the internal and superficial tibio-tarsal ligaments. : 5. An interosseous ligament, attached to the four bones composing this articulation. It is provided with a particular synovial membrane which always communicates, in front, with the tibio-tarsal capsule. This membrane is prolonged, superiorly, between the calcis and astragalus, to lubrify two of the facets by which these bones come into contact; and, in addition, it descends between the cuboid and scaphoid bones to form a third pro- longation for the anterior cuboido-scaphoid arthrodia. Movements almost null. TARSO-METATARSAL ARTICULATION.—This joint, formed by the meeting of the three tarsal bones—the cuboid and the two cuneiforms—with the three bones of the metatarsus, is fixed by the lateral superficial ligaments of the tibio-tarsal articulation, the calcaneo-metatarsal ligament, those which have been named the astragalo-metatarsal and tarso-metatarsal, and by a strong interosseous ligament which naturally forms three fasciculi. The synovial membrane proper to this joint ascends into the small anterior cuboido-cunean arthrodia, and into that which unites the two cuneiform bones; it descends to the intermetatarsal articulations. Movements nearly null. In all the domesticated animals except Solipeds, the tarsal articulations offer some diffe- rential peculiarities whose study is without interest, as it is without utility. It is only necessary to remark that the immobility of the tarsal joints, properly called, is less absolute than in Solipeds, owing to the peculiar configuration of the articular surfaces of some of the bones composing them. ‘’hus, in the Ox, Sheep, Goat, and Pig, the caleis is joined to the astragalus by a real trochlear articulation, and the latter bone is united to the scaphoid by a diarthrodial joint of the same kind; a mode of articulation much more favourable to motion than that of the p/aniform diarthrodial joint, In the Dog and Cat, the same result is obtained by the reception of the head of the astragalus into the superior cavity of the scaphoids, In Ruminants and the Pig, it is also observed that the tibio-tarsal articulation is formed by the tibia and fibula in the one direction, and by the astragalus and os caleis in the other, i 4 Bt CHAPTER III. OF THE ARTICULATIONS IN BIRDS. Tue study of the articulations in birds will only arrest us for a few moments, as it will be confined to some remarks on the intervertebral occipito-atloid and temporo- maxillary joints, the only ones exhibiting a special conformation worthy of attention. Intervertebral aeitelatne = The great mobility of the neck of birds is not only due to the fact of its length, relatively considered, but also to the peculiar manner in which the vertebre of this portion of the spinal stalk are articulated. It will be remarked that ARTICULATIONS IN BIRDS. 173 these do not unite by their bodies in the form of a continuous series of amphiarthroses, as in the domesticated mammals; but that instead of these mixed articulations there are _ veritable diarthroses, which may be included in the class created by Cruveilhier under the title of articulation by reciprocal ball and socket, each vertebra becoming connected with the adjacent vertebrae by means of facets convex in one sense and concave in the sense perpendicular to the . These facets are manifestly covered by cartilage of incrustation ; and it appears that, instead of their being applied directly against the opposite oe. ahr present a precisely inverse conformation, they are separated by an extremely thin fibro-cartilaginous disc, which resembles the interosseous meniscus of the temporo-maxillary articulation in the Carnivora of the Cat species. Two loose capsules, separated by tlis interarlicular lamina, complete the framework of each articulation, and favour the play of the vertebre on one another. This arrange- ment has only, so far as we are aware, been observed in the swan, and that very oe int ; but it probably belongs to the entire class of birds, for until now we have with it in all the individuals submitted to examination. Tn its dorso-lumbar and sacral portion, the spine is a single piece, in consequence of the consolidation of the vertebra, and does not abet any proper articulations. In the coccygeal region, the mobility of the spine re-appears; but it is far from being so marked as in the cervical region ; the vertebre here are united by amphiarthrosis, an not by reciprocal ball and socket. Occ id articulation.—It has been shown that there is only one more or less heroidal condyle of the occipital bone, and a single cavity on the anterior margin of spinal canal of the atlas. The occipito-atloid articulation is therefore a true enar- with varied and very extensive movements; a disposition which accounts for the facility with which birds can pivot their heads on the superior extremity of the vertebral stalk. oy Saddle a articulation —The play of this articulation offers one peculiarity in that it causes, during the separation of the mandibles, not only the depression of the inferior, but also the elevation of the superior mandible. The arrangement which permits this movement has been already made known; but yet it is difficult to understand, be- cause there is no active agent, no proper muscle to directly effect it. Nevertheless, the mechanism which executes it is most simple, and may be given in a few words: Thus, we know that the square bone, interposed between the temporal and maxillary bones, like the interarticular meniscus of mammals, is united outwardly with the jugal bone, and inwardly with the pterygoid. We know also that the latter rests, by means of a diarthrodial facet, on the body of the sphenoid, and that it abuts against the posterior extremity of the palate bones; while the first, the zygomaticus, is joined directly to the i bone. The superior jaw, it is also known, is movable on the cranium, because of the flexibility of the cartilages or bony plates uniting these two portions of the head. It may then be added, that the square bone receives on its anterior one or two small muscles which are attached to the base of the cranium, and that bones may be pushed, or rather drawn forward, by the contraction of these muscular fasciculi. It is this projecting, or pushing, transmitted to the upper mandible through the medium of the jugal bone on the one side, and the pterygoid bone on the other, that produces the elevation of that mandible. Nothing is easier than to prove it; it is only necessary to take the head of a bird, denude it of all its soft and press with the fingers behind the two square bones, to imitate the action of the elevator muscles; we then see the internal extremity of the dee bone glide on the facet of the sphenoid, and push before it the palatine bone, uring which the zygomatic bone acts in the same manner on the maxillary; and in this way is produced, through the influence of this postero-anterior propulsion, the ascending movement we undertook to explain. THIRD SECTION. THe MusCcLEs. Arrer the study of the bony levers and their articulations, comes the description of the agents whose function it is to move them. These are the muscles, fibrous organs possessing the property of contracting under the influence of a stimulus. 174 THE MUSCLES. They are distinguished as striated (or striped) and non-striated (or unstriped) muscles, according to the character of the anatomical element composing them. : The non-striated (or unstriped) muscles are removed from the influence of | the will, and belong to the organs of vegetative life. They are also designated as internal muscles, or muscles of organic life. The striated (or striped) muscles, differ from the first in that, with the exception of the fleshy tissue of the heart, their contractile power is immediately placed under the influence of the will. They are more particularly concerned in the execution of the functions of relation, which causes them to be named the external muscles, or muscles of animal life. These muscles are nearly all attached to the skeleton, and represent the active agents in the movements of the osseous framework; they will, therefore, be the only ones referred to in this place, in studying the locomotory apparatus. But before entering upon the particular description of each muscle, we will allude to the general considerations relative to their history. CHAPTER I. GENERAL CONSIDERATIONS ON THE STRIATED MUSCLES. THE STRIATED MUSCLES IN GENERAL. In this first paragraph, we will survey in a general manner the volume, situation, form, direction, attachments, relations, and names of the muscles belonging to the locomotory apparatus. A. Vo.umn.—Nothing is more variable than the respective volume of the external muscles. What a difference there is, for example, between the small scapulo-humeral muscle and the long vastus or ilio-spinalis (longissimus dorsi) ! and what a number of intermediate sizes between these three points of comparison! There are consequently very great, great, medium, small, and very small muscles. The weight of the total mass of these organs varies according to the species, age, sex, and state of health; but taking a general average, it will be found that it represents nearly one-half the entire weight of the body. B. Srrvation.—There is no need to insist upon the fact, that a knowledge of the situation of the muscles is one of the first objects to be acquired with regard to their disposition. They may, like the bones, be described in two ways. 1. In relation to the median plane of the body, from whence their division into pairs and single muscles. The last, very few in number, are far from exhibiting the symmetry which exists in the bones of this division, as may be seen in the diaphragm. 2. In relation to the other organs, such as the bones and surrounding muscles. C. Form.—With regard to their absolute form, the muscles, again, like the bones, are classed as long, wide, and short. muscles.—These muscles are more particularly met with in the limbs. Provided with a principal axis, to which we may ascribe the effect of their contraction, they present a middle portion—usually protuberant, and 4 ‘ _- = 5. F y : mu GENERAL CONSIDERATIONS ON THE STRIPED MUSCLES. 175 _ two extremities of unequal thickness; the most voluminous, always turned upwards, is metaphorically designated the head, the other the tail. They are most frequently fusiform, sometimes conical, but rarely cylindrical, ismatic or flattened into thin bands. “There is a particular kind of long muscles which have no analogy with those of the extremities, except in their external appearance, They are those which lie below, but more particularly above, the spine. Although ¥ at the first glance they appear simple, yet they present as many distinct fasciculi as there are vertebrw. The transverse spinous (spinalis dorsi), ete., is no doubt an elongated fasciculus like the sartorious, etc., but the structure of this fasciculus has nothing in common with that of the latter muscle : it is a series of small fasciculi which have each their distinct origin and termination, and only appear as a single muscle because they are in juxta- position.” —Bichat, ‘ Anatomie Générale.’ Wide muscles—Wide muscles are those which have two principal axes, and are stretched beneath the skin, or around the great cavities of the trunk, which they concur in inclosing and separating from one another. They are elliptical, quadrilateral, triangular, trapezoid, etc. muscles.—These are found chiefly around the short bones, or. at the periphery of the articulations which are deeply buried under enormous muscular masses. Although their name indicates that their three axes offer nearly the same dimensions, yet there is most frequently one, and even two, which predominate. They may therefore be assimilated, in this respect, to the long or wide muscles. D. Drmectioy.—Cruveilhier has justly remarked, that the direction of a muscle is one of the most important features in its history; for it allows the determination of the angle of incidence of the muscle on its arm of the lever, the power of its action, and the nature of its uses. With regard to the direction of the muscles, we may observe: 1, The form of their principal axis; 2, The relation of this axis to the plumb- line ; 3, Its comparison with the axis of the bony levers which the muscles surround or move. a. A muscle is termed rectilinear when its principal axis is straight; it is curvilinear, or circular, if this axis describes a curve more or less marked ; it becomes inflected when’ it proceeds in a certain direction, and afterwards turns on a bony or cartilaginous pulley in another direction : that is to say, when its principal axis is broken into several lines. If the muscle offers two axes, it will be flat or concave, these being one or the other, or straight or curvilinear. b. With regard to the direction of the muscles to that of the plumb-line, it is either vertical, horizontal, or oblique, expressions which carry their own definition and require no explanation. ¢. If the direction of the muscles be compared with that of the bony levers they surround and move, it will be found that they are either parallel to these levers, or form with them angles more or less acute. The proper direction of the bones being known, it is sufficient to indicate that of the muscles to clearly establish this comparison. For instance, in saying that the majority of the muscles of the shoulder are oblique from above to below, and from before to behind, it is understood that these muscles are parallel to the scapula, and that their incidence on the humerus takes place at a right angle. _ _E, Arracuments or Insertions.—This is undoubtedly the most essential part of the study of the muscles; for with the knowledge of their insertions 176 THE MUSCLES. we may determine their extent and direction, and even their relations By the term attachment, fixed insertion, or origin, is meant the point of | the muscle which most usually remains fixed while that organ contracts; — the attachment, movable insertion, or termination is the name given to that — portion which corresponds to the lever displaced by the muscular contraction: Muscles are frequently met with whose two insertions are alternately fixed or movable ; and in such cases care is taken not to give these insertions one or other of the designations. + 3 The fixed insertion is often confounded with that of other muscles; the movable insertion is generally free and independent. 5. 7 The muscles are sometimes directly attached to the bones by the ex- tremities of their fleshy fibres; but most frequently they are fixed to these inert levers through the medium of a tendon or an aponeurosis, whose volume is less considerable than that of the fibres. Without this latter | disposition, the surface of the skeleton would not have been sufficiently . extensive to give insertion to all the external muscles, ' . The attachment of the muscles to the bony levers is effected by a kind of fusion between the fleshy or tendinous fibres, and the periosteum. — F. Retations.—The indication of the relations of the muscles completes the idea of their situation, and is of great importance in a surgical point of view. They should, therefore, be studied with all the precision possible. The muscles entertain relations either with the skin, the bones, other muscles, or with vessels and nerves. a. It is only, properly speaking, the subcutaneous muscles, such as the panniculus carnosus and the muscles of the face, which are really in im- mediate contact with the skin. The others are separated from it by the aponeurotic fascia which will be described as the appendices of the muscular system. : b. The superficial muscles are only related to the bones by their ex- tremities. Those which are deeply situated are immediately applied by their bodies against the bones of the skeleton. c. The muscles are related to each other in a more or less intimate manner. Sometimes they adhere closely to one another; and at other times they are separated by interstices filled with fat or cellular tissue, and generally traversed by vessels and nerves. d. The connections of the muscles with the latter organs sometimes assume a remarkable character; this is when one of them accompanies, like a satellite, the vascular and nervous trunks concealed beneath its deep face. There is in this circumstance an important fact with regard to surgical anatomy. G. Nomenciature.—Before the time of Sylvius, the muscles had not received particular names. Since the days of Galen they had been dis- atelahed ‘by. the numerical epithets of first, second, third, etc., to indicate their place and their order of superposition in the regions to which the belonged. It is in this fashion that they are designated in the Italian wor. on the Anatomy of the Horse by Ruini. Sylvius was the first to give the muscles real names; and his example being followed by succeeding anthropotomists, the nomenclature of these organs was soon completed. But no general view, no methodic spirit guided Sylvius and his successors ; it was sometimes their form, and sometimes their direction, position, uses, etc., to which the muscles owed their names, and — — a OS « —_—_ ow GENERAL CONSIDERATIONS ON THE STRIPED MUSCLES, 177 applied this nomenclature to the horse, but modified it in many Chaussier, struck by the imperfections of the nomenclature introduced ~ into science by Sylvius, sought to substitute for it another much more philo- sophical, This anatomist gave to each muscle a name formed by two words licating the insertions of the organ. Girard imported this ingenious Nevertheless, notwithstanding its advantages, this new nomenclature __ did not supersede the old one; because it ceased to be eorrect when applied _ to comparative anatomy, the same muscles not having the same insertions +in all the species.’ 1 Tt is not, however, that the ancient nomenclature has more advantages in this deltoid, apie the new. What can be more improper, for example, than the names of splenius, soleus, digastricus, etc.? Do the muscles which receive these desig- i considered in mammals only, offer in all species the form or the structure which justifies the employment of these names in the human species? Afe the distinctive epithets of great, medium, little, etc., given to many of them, reasonably applicable in every case? May not the same objection be urged against the majority of the names . pata it to be indispensably necessary to create one ; indeed, we are inclined to think '- immortal ‘ Philosophie Anatomique, a principle to which modern science certainly owes its This is a — which it is our intention to treat in a special work; but we may, indicate here the manner in which it presents itself to us. We are desirous that the myological nomenclature should rest entirely, in the first place, the relations of the muscles with the pieces of the skeleton, or with other organs equally very important ; in the second place, on the reciprocal connections of the muscles. : is our plan; and it is not precisely new, for the old anatomists were often with it, though unwittingly, as the principle on which it is founded was to irely unknown; this circumstance, however, immediately leads us to an appre- its value. For instance, what could be happier than the name of intercostals the muscles situated between the ribs, and their distinction into external and ? Here we have names which indicate the relations of the muscles they desig- ith the portions of the skeleton and the reciprocal connections of these muscles. It be applied in an equally rigorous manner to every species. We may also cite pracostals, the intertransverse, the transverse spinous, the subscapularis, the __—s supraspinous, the subspinous, etc., as they are found in a greater or less marked degree ___ in identical conditions. Other muscles have received names derived in part from their situation, and in part from their volume. These names are far from being as convenient as the first; as may be judged from the following examples : In the majority of vertebrate animals, there are three important muscles situated _ above and behind the pelvis, and forming the basis of the buttock; they have been designated gluteals, and this name is convenient, because it designates their situation. But to distinguish them from each other, regard has been had to their volume ; so that there is a great,a medium, and a small gluteus. This isan error, however, for the volume of the muscles is subject to the greatest variations, and a voluminous muscle in one species may be a very small one in another, and vice versé. The musele analogous to the maximus in Man has been described by Bourgelat as the minimus, and by Lafosse and Rigot as the medius, With regard to the gluteus medius of Man, its representative in the lower animals has been designated as the maximus by the majority of veterinary anatomists. What confusion! And how easy it was to evade it by distinguishing these muscles, not by their volume, but by their reciprocal connections, which are the same in pati Hise Is it not, indeed, more natural to substitute the names of superficial, The Hin iE Fe ay and deep gluteals, for those of great, ete ? same remark is applicable to the muscles which, in Man, cover the anterior aspect of the chest. Designated in common, and justly so, as pectoral, these muscles are wrongly distinguished into great and little; for the last, which is already an N 178 ‘ ' THE MUSCLES. In this work we will follow the nomenclature of Bourgelat, which | wilt) "ls however, be submitted to some change. But as the names given by mane Vee? , ee ee aed _junctival sheath—the perimysium. muscle. The conjunctival sheath enve- : perimysium. GENERAL CONSIDERATIONS ON THE STRIPED MUSCLES. 179 either of the helicoid disposition of the fibrille, or of the fusion of the sarcous elements which compose the latter, according to the admitted opinion as to the structure of the contractile element. The muscular fibres are united parallel to each other to form secondary fasciculi, which are surrounded by a con- The secondary fasciculi are laid together to constitute more voluminous fasciculi which, in their turn, form the entire Fig. 97. loping the muscle is named the external B. Tenpons anp Aponrvroses.—The tendons are white, nacreous, round, or flattened cords fixed to the extremities of the long muscles. They are composed of fasciculi of condensed conjunctival tissue, affecting a parallel direction, and united to one another by connective sheaths. The aponeuroses belong almost ex- TRANSVERSE SECTION OF FROZEN MUSCLE, MAGNIFIED 400 DIAMETERS, N, Nerve; M, Muscular fibre, surrounded elusively to the wide muscles; they are formed of several planes of parallel fibres which are not intercrossed in their middle part; at their superficies, how- ever, the fibrous fasciculi are matted toge- ther in a more or less inextricable manner. It is very interesting to study the mode of union of the muscular fibres with the tissue of the aponeuroses and tendons, as well as the reciprocal rela- by portions of six others.—a, Nucleus of the nerve sheath; 5, Nucleus of the sarcolemma; c, Section of nucleus of terminal plate of nerve; d, Transverse section of terminal plate, surrounded by granular material; e, Transverse section of muscle nuclei; f, Fine fat drops. The angular dark particles are sections of sarcous elements: the clear intervening spaces represent the fluid isotropal part of the muscle substance. tions of these two parts. The muscular fibre may be found passing in the same direction as the tendon, or it may fall upon the latter obliquely. In both cases there is no insensible transition between the muscular fibre and the fasciculus of the fibrous tissue ; on the contrary, the contractile fibre terminates by a rounded extremity, which is buried in a corresponding depression in the tendon or aponeurosis. The union of the muscular with the fibrous tissue is very intimate ; when the muscles are submitted toa degree of traction sufficient to cause a rupture, this never happens at the point of union, The tendons commence sometimes by a hollow cone, which receives on its internal face the insertions of its muscular fibres; and sometimes by a thin point, often divided, which is plunged into the substance of the muscle. It is worthy of remark that a muscle provided with two tendons shows the first-named arrangement at one of its extremities, and the other at its oppo- site extremity ; so that all the fibres which compose the muscle offer nearly the same length, those which leave the summit of the internal tendon being fixed to the bottom of the hollow cone formed by the second tendon, and so on reciprocally. The muscular fibres which are continued by the fibrous fasciculi may bo divergent or parallel. In the first case—the diaphragm, for example—the connective fibres run in the same direction as the muscular fibres. In the second case, several arrangements may be observed : Nn 2 180 THE MUSCLES. 1. Tendons may pass in the same direction as the muscular fibres. This — is the most simple manner. But the muscle may be divided into two bodies or bellies by a middle tendon ; it is then called a digastric muscle. : 2. Muscular fasciculi, passing altogether from the same side to become united into a tendinous cord, constitute a semi-penniform muscle. ; 3. Muscular fasciculi may be implanted to right and left of the tendon, and form a pennated or penniform muscle. “ This arrangement of fibres demonstrates that the length of the muscle, the length of its belly, and the length of its muscular fibres, should be care- fully distinguished. The first term is applicable to the whole of the Lyuscle, the tendon included; the second, to the fleshy body of the muscle, with the exception of the tendon; the third, to the muscular fasciculi constituting this fleshy body: the latter idea is the most important, for it alone indicates the amount of contraction a muscle is sus- Fig. 98. ceptible of, and consequently the possible ex- _ tent of movement it is capable of effecting.”— Beaunis and Bouchard. C. Vessers anp Nerves.—The muscular tissue receives much blood; the fibrous tissue very little. The arteries are large, numerous, § and each is acccompanied by two veins. The capillary vessels anastomose in such a manner as to form rectangular meshes, whose greatest diameter is directed towards the length of the , muscle, a parce avelnrapioc rage a The lymphatic vessels of the muscles are few ; they sometimes penetrate their interior in following the capillaries; at other times they remain on the surface, in the external perimysium. The exist- Fig. 99. ence of lymphatics has not yet been. demonstrated in tendons, aponeu- roses, or synovial membranes. The nerves emanate from the cerebro-spinal centre. At their terminal extremity they offer a small enlargement, called Rouget the terminal motor plate, and by Doyére and Kiihne the ner- vous colline (hillock). It is ad- mitted that the motor tube traverses the sarcolemma, losing its enve- PORTION OF AN ELEMENTARY MuscuLAR Finer, lope; and that the substance of the WITH FOUR DARK-BORDERED FIBRES (a) cross- cylinder is spread over the surface ING ITS SURFACE; after Beale. of the muscular fibrille to form the b, Capillary blood-vessel, with fine nerve-fibres; yyotor plate or nervous colline. a few only of the transverse markings of the muscle are represented; c, Two of the dark- pyygIc0-CHEMICAL PROPERTIES OF bordered nerve-fibres passing over the ele- mentary fibre to be distributed to adjacent StRIEAD, MURS fibres. This arrangement, in which a dark- Muscles are soft organs, re- bordered nerve-fibre, distributed to muscle, markable for their more or less divides into branches, one of which passes to : ‘ : a vessel, while the "other ramifies upon a deep- red colour, which Varies with muscle, is frequent. Magnified 700 diameters. the species, and even in these with the age and health of the animals. 7 ¢ j 4 GENERAL CONSIDERATIONS ON THE STRIPED MUSCLES. 181 By desiccation, muscles become hard and brown ; by repeated washing they assume a straw-yellow tint. Muscles are extensible and elastic; they are also tenacious, and their tenacity is more marked during life than after death. It has been remarked that the juice impregnating the muscular tissue is distinguished from the serum of the blood by an acid reaction. (The fluid or “muscle plasma” obtained by pressing flesh, is either neutral or slightly alkaline. It soon coagulates and separates into two portions—a semi-solid portion, “myosin,” and the fluid serum that at ordinary temperatures quickly acquires an acid reaction.) It holds in solution a variable quantity of albumen, casein, fat, a little creatine, creatinine, and a somewhat large proportion of lactic acid. The solid substance of the muscle may be partly transformed into gelatine by boiling in water; but its largest portion is a nitrogenous substance, soluble in dilute hydrochloric acid, called “ syntonine,” or muscular fibrine ; it differs but little from the fibrine of the blood. PHYSIOLOGICAL PROPERTIES OF THE STRIPED MUSOLES. In this paragraph will only be discussed the development of the muscles, muscular contractility, and the part the muscles assume in locomotion. A. Drvetopment or tHE Muscixes.—A muscle is derived from a mass of embryonic cells. Each cell becomes considerably elongated, and its nucleus - becomes multiple, to constitute a muscular fibre. The membrane of the cell, enormously developed, forms the sarcolemma, while the contents of the cell, hecoming more dense, divide longitudinally and give rise to the contractile fibrille. Lastly, when the muscles are formed, they grow by the augmenta- tion in length and thickness of the primary fasciculi or muscular fibres. B. Muscvtar Contractismiry.—Muscles possess the property of con- tracting under the influence of a natural or artificial stimulus. Muscular contraction is the phenomenon resulting from the operation of this property. Muscles in a state of contraction are the seat of physical and chemical phenomena ; they change their form and consistency, and become the theatre of a relatively abundant production of carbonic acid, creatinine, and inosinic acid. During contraction, it has been remarked that the muscular fibres contract by increasing in volume, like an india-rubber tube left to itself after being extended : the zig-zag doubling mentioned by Prevost and Dumas has not been observed. But these physical and chemical modifications, important as they are in MUSCULAR FIBRE IN A STATE OF CONTRACTION IN THE CENTRE; THE STRLE APPROXIMATED; THE BREADTH OF THE FIBRE INCREASED; AND THE MYO- LEMMA RAISED IN VESICLES ON ITS SURFACE, & physiological point of view, cannot longer be dwelt upon here. It is parti- ly important to speak of muscular contraction. A muscle that contracts becomes shortened ; its two extremities approach each other if they are free ; or one draws near the other if the latter is fixed 182 THE MUSCLES. to an immovable point. If the extremities of a muscle are attached to two movable levers, its contraction will bring about the displacement of one or other of these; from this a movement is produced. The degree of shortening of a muscle varies, according to its being entirely free, or having a resistance to overcome. The mean limit of this shortening is about one-fourth the length of the muscular fibres; from this it will be understood that the movement produced by the contraction will be in proportion to the length of the fibres; though in this appreciation it will be necessary to keep in mind the density and energy of the fibre, as well as the intensity of the contractile stimulant. A og As each fibre represents a force independent in its action, it results that we may judge of the power of a muscle by the number of its fibres, or its volume. Muscles are often aided in their action by mechanical conditions: such as | the disposition of the levers on which they act, the direction of the museular fibres in connection with these levers, and, lastly, by the presence of lamelle or elastic cords. C. Uses or Muscrxs.—There are flexor, extensor, abductor, adductor, - rotator, and other muscles, for all the movements of which the articulations — are the centre. : To determine the functions or uses of the muscle, it is sufficient to know ‘ their insertions, and the mode in which the bones furnishing these insertions articulate with each other. The result of muscular contraction being influenced by the form of their principal axis, and the length and direction of their levers, it is necessary to briefly examine these two points: 1. The immediate effect of the contraction of rectilinear muscles is the ap- proximation of the bones to which they are attached. This approximation is usually brought about by the displacement of a single ray: that which receives the movable insertion of the muscle. Sometimes, however, the two — rays move simultaneously, or they are alternately fixed and movable. ; The first result produced by a curvilinear muscle is the straightening of its component fibres ; after which it may act on the bony levers as do the rectilinear muscles, if its contractile power be not entirely expended. When a muscle is quite circular, its only action is to contract the opening it cireum- scribes. With regard to the inflected muscles, their action can only be estimated from their point of inflexion ; they operate as if this point represented their origin or fixed insertion. 2. The muscular powers are submitted to the statical and dynamical laws which govern the theory of levers ; for the bony rays are only levers moved by the muscles. In the locomotory apparatus we find the three kinds of lever recognised by physicists. Thus the head, extended by the great complexus muscle, represents an interfixed, or lever of the first class ; the foot, extended by the - gastrocnemii muscles, offers an example of the interresisting, or second kind, when this member remains fixed on the ground ; lastly, the lower jaw raised towards the upper by the masseter muscle, forms an inferpuissant or third kind. It is worthy of remark that the arm of resistance in the bony levers is always extremely long ; a circumstance which favours speed and the extent of movement at the expense of power. On the other hand, muscles are rarely perpendicular to the arm of their GENERAL CONSIDERATIONS ON THE STRIPED MUSCLES. 183 levers, at least at the commencement of their action ; another circumstance which again diminishes their energy. APPENDAGES OF THE MUSCLES. _ These are: 1, The enveloping or contentive aponeuroses; 2, The serous or mucous burse ; 3, The tendinous and synovial sheaths. __ A. Contentive Aronevrosrs.—These are layers of white fibrous tissue, which envelop, in common, all the muscles of one or several adjoining regions, principally those of the inferior rays of the limbs, where they con- stitute a kind of hollow cylinder. These aponeuroses are formed by very resisting interwoven fibres, which are attached to the bones at numerous points. At their periphery they receive the insertion of one or several muscles, which keep them more or less tense. Their external face responds to a thin fibro-cellular layer that separates them from the skin. The internal face sends lamellar prolong- ations between the muscles, which are destined to isolate these organs in _ special sheaths. F The aponeuroses maintain the muscles in their position, and sustain them during their contraction. B. Szrovus Bursaz.—The serous or mucous burs are small cavities, filled with a serous fluid, which are met with at those points where the muscles glide over resisting surfaces. They are generally orbicular or rounded, and their interior is often divided by fibrous bands. _ Their walls are formed by slightly condensed conjunctival tissue, and may be lined by a pavement epithelium; in which case it is believed that the serous bursa is produced by the simple dilatation of one of the con- junctival meshes. C. Tzyprvovs Sxearus: anp SynoviAL Mempranes.—Tendinous sheaths is the name given to the half-bony, half-fibrous, sometimes exclusively fibrous, gliding grooves into which the tendons pass when they are inflected to change their direction. ' The tendinous synovial membranes are serous membranes lining the ten- dinous sheaths and covering the tendons at the points where these two parts C d. They secrete a synovial fluid quite like that of the articulations. When they almost completely envelop the tendon, and are afterwards carried to the walls of the sheath, they are termed vaginal. Their walle are composed of: 1, A very fine conjunctival membrane, con- founded by its external face with the tendinous sheath, by the other face with the tendon; 2, A simple layer composed of pavement epithelium, extended over the whole or a part of the internal face of the conjunctival membrane, MANNER OF STUDYING THE MUSCLES, A. Oxasstrication.—To facilitate the study of the muscles, two methods may be employedin grouping them. The first consists in classifying them according to their uses ; describing, for example, all the flexors, extensors, etc., of the same region. In the second method, the uses of the muscles are not taken into account, their relations only being considered; and they are divided into groups or regions, which comprise all the muscles situated around a bony ray. The latter is the method now adopted, because it is the most convenient, useful, and rational. (Leyh describes the muscles by layers, or according to their situation, 184 THE MUSCLES. which, he asserts, facilitates the study of anatomy in a surgical point of | view). . Ng . B. PreraraTion.—We will limit ourselves to some general remarks on the following ints: Choice of a subject.—If there is for disposal a certain number of subjects from which it is possible to make a selection, the preference should be given to those have the muscular system best developed; not that large, soft, lymphatic herses enormous masses of muscle should be chosen, for these animals are always less convenient than small or middle-sized, well-bred horses. Asses and mules, when very emaciated, answer well for the preparation of the muscles. Position of the subject.—It is necessary to place the subject, immediately after death, in a convenient position, in order that the cadaveric rigidity may set in while it isin that attitude. Without this precaution, the various parts of the y may assume an incon- venient shape or direction, and all attempts to amend them will prove almost unayailing, particularly in the larger animals. Three principal positions may be given to subjects : 1. The animal is in the first position when it is placed on its back, the four ex- tremities in the air, and maintained in that posture by means of long ed . round the pastgrns and fixed to the movable rings which terminate the extremity of the four bars of the wheeled-table on which the subject is laid. The head should be beyond — the end of the table and rest upon a stool. The animal should always be placed in such _ a manner that the head be opposite the fore-part of the table, so that the movements of the pole or shaft be not impeded during the displacement of the apparatus. In order that the neck be not twisted to the right or left, in attaching the fore-limbs the subject should be raised so that the withers rest lightly on the table. According to the of the animal and the length of the bars, the ropes should be passed around either the pasterns, above the fetlocks, or even above the knees. 2. To place the animal in the second petition, it is turned on the belly, the two ; thighs flexed, the extremities carried beyond the table, and the head fixed between two bars by means of a rope passed under the zygomatic arches. 3. The subject is in the third position when it rests on its side. _ Rules to be observed Cer™"he preparation.—1. By no means, if ible, remove the skin from the regions to bé dissected until quite y to begin the di ion. If thisis impossible, then take the precaution of enveloping these regions in damp cloths, or in the animal’s skin, to prevent desiccation of the aponeuroses and the superficial muscles, 2. To disse ) a muscle, it is necessary to remove the aponeureses or the other muscles whic! over it, the cellular tissue enveloping it, and the fat, glands, vessels, and nerves lodged in the neighbouring interstices. The aponeuroses should be removed in shreds by making them very tense with the forceps, but without raising them, and causing the blade of the scalpel to glide between the fibrous and muscular surfaces, keeping it always parallel to these two planes. The covering muscles should not be entirely excised, but ought to be cut through the middle, across their fibres, and the . ends thrown back; in this way it is always possible to replace a muscle by bringing the ot two portions together; the study of its relations is then much more easy. The cellular | tissue is got rid of by removing it with the forceps, and carrying the edge of the scalpel in the re-entering angle formed by the cellular layer and the surface of the musele. This method also suffices for removing aponeuroses when they are slightly adherent to the muscular fibres. But when they give attachment to these by their under face, as may be noticed in the external scapular aponeurosis, it is necessary to have recourse to the method indicated above. To remove fat, glands, etc., scissors will be found very advantageous. Order to follow in power all the muscles of the same subject, and to derive most advantage therefrom.—1. Place the subject in the first position, and commence by study- 7 ing the muscles of the inferior abdominal region. Then excise them, leaving the rior extremity of the great pectoral muscle, the prepubic tendon, and the crural arch intact. The abdominal cavity having been emptied of the viscera it contains, dissect and study successively the diaphragm, the internal crural region, except the deep muscles, the sublumbar region, the femoral and posterior crural regions, the superficial muscles of the inferior cervical region, and the pectoral region. 2. After detaching for future use one of the anterior limbs, the animal is placed in the second position, and one after another oa f be dissected the muscles of the ear, those of the superior cervical region, the croup and costal regions, except the triangular musele, and the spinal region of the back and loins, se GENERAL CONSIDERATIONS ON THE STRIPED MUSCLES. 185 8. The regions of the anterior limb may be prepared at the same time, or immediately _ 4. Separate the two posterior limbs by sawing the femurs through their middle, and J proceed to the dissection of the muscles of the posterior leg and foot. y isolated for the preparation of the coccygeal muscles, and the deep internal crural region, nearly as they are represented in figures 90 animal being placed on its side, the pectoral cavity is opened by sawin the ribs near their extremities; on the two particular portions thus obtain studied, in one part, the triangularis of the sternum, and in the other the deep uscles of the inferior cervical region, including the long musele of the neck and anterior and lateral straight muscles of the head. yf y, the head is disarticulated and the muscles of this region are prepared. The subject may afterwards serve for the study of nearly all the articulations. ion of the muscles—The muscles may be preserved by immersing them in iate fluids, and the muscular preparations by drying them. A large number of liquids preserve muscles from putrefaction, We may mention alcohol ; a mixture of alcohol and spirits of turpentine; alcohol, water, and chloroform ; a solution of sulphate of iron, bichloride of mercury, or arsenious acid. The best preservative fiuid, however, is nitric acid diluted with water, in the proportion of one of the former to three of the latter. The acid hardens the muscles and softens the conjunctival issue; this allows all the interstices to be completely cleared out, and even its the primitive poomvalenteeionlh which have been concealed by the white tissues to be exposed. i By a knowl of the action of the muscles, the surgeon is able at once to explain the causes of disp ent in the various forms of fracture, or the causes which produce < Surgeon in estimating the value to be placed upon the external conformation presented by animals intended for different kinds of labour. “In ing,” says Mr. Holden, “ there are four principal objects to be constantly borne in mind by the student: Ist, The impression on the memory of those facts of general anatomy tauglit in the lectures. 2nd, The study of those parts of the body more y concerned in surgical affections and operations. 3rd, The education of the sense of touch, and of the hand in the use of instruments; and 4th, The education of the eye in the knowledge of the several tissues of the body, in various positions, and yarying circumstances. . . . The education of the eye is a gradual and tedious process, but one which is pretty certain to be satisfactorily accomplished if the student do but use his hands properly, and therefore a few words on the manual part of dissection may not be out of abs. First, as to the instruments requisite for dissection. A case, containing six or eight scalpels, two pairs of scissors, a pair of dissecting forceps, a set of chain-hooks, a blow- pipe, and a probe, will enable the student to make all requisite dissections, supposing is allowed the use of a saw and chisel in the dissecting-room. Great variety exists in dissecting both as to form and expense, but so long as the instruments themselves are strong and good, the simpler the case the better. Scalpels for dissection are made of two principal shapes; in one, the edge is bevelled to the point, the back being straight; i the other, both back and edge are bevelled to a point midway between the two. The latter form is preferable for most purposes. The blade should not be more than an inch and a half long, and never double edged ; but the material of which the handle is constructed is a matter of indifference. 186 THE MUSCLES. | — “For all ordinary dissection, it will be found most convenient to hold the scalpel — like a pen; but for cleaning the fascia off muscles and following out small nerves, it is — better to hold it reversed, so that the back of the knife may be against the tissue which is to be preserved. In making the first incision through the skin of a limb, or inany other position where a long incision is required, the knife may, with advantage, be under the hand, by which the wrist has more play, and the student has the opportunity of practising a mode of holding the knife, which he will find very useful when operating on the living body. “The forceps should be broad at the extremities and coarsely serrated, so that it may retain a firm hold on small portions of tissue. It is very important that the should not be too strong in the spring, for in that case it becomes so fatiguing to hand that it is impossible to continue its use for any length of time. The forceps should be held lightly between the thumb and the first and second fingers of the left hand, which may be steadied by resting the little finger on a neighbouring part. “The chain-hooks should be strong, and bent in the direction of the thickness and not of the breadth of the steel, as is sometimes done. These latter are very inferior, being liable to be unbent under any considerable strain. Care should be taken that the chains are firmly linked, and that the central ring is sufficiently stout to bear any foree that may be applied. The scissors should be large and strong, and it will be found advantageous to have one curved pair, which is very useful in preparing the li 8. “The student will do well to bear in mind that he will probably be called upon in — after life to operate on the living body, the only true preparation for which is ul dissection; he should therefore, as far as possible, conduct all his dissections as — methodically, and with as much care, as if operating on the living body. “ The student should bear in mind that his manual labour is only a part of his duty, and will be thrown away, unless he at the same time study the description of the part upon which he is engaged ; he should not, therefore, carry the dissection further than he " can learn the description on the same day, and at the subject, and should, if possible, re-peruse the description in the evening, and always on the next morning, before carrying the dissection any further.”) we ee II. THE MUSCLES OF MAMMALIA. Articte I.—Mousotes or tor Trunk. ~ , , SUBCUTANEOUS REGION. Tus only comprises a single muscle, the fleshy panniculus (panniculus carnosus), destined to move the skin covering the trunk. Strictly speaking, however, we may describe as dermal muscles all those which are attached to the inner surface of the superficial integument—the muscles of the face, for example, Fleshy Panniculus, Preparation.—Place the animal on its side, and carefully remove the skin, allowing the cuticular muscle to remain on the subjacent muscles. Situation—Form— Extent.—Situated on the inner surface of the skin cover- ing the sides of the thorax and abdomen, the fleshy panniculus is an immense broad muscle, irregularly triangular in shape, thin at its borders, and — thicker in the middle than elsewhere. The upper border corresponds to a curved line, convex superiorly, and extending obliquely from the flank to the withers. ‘The inferior border is carried horizontally from the flank to the posterior border of the olecranian — mass of muscles, passing along the upper margin of the great pectoral muscle, which it covers, and to which it adheres somewhat closely. The MUSCLES OF THE TRUNK. 187 anterior border descends from the superior extremity of the shoulder on to the muscles of the fore-arm. _ Structure—Attachments.——The fleshy fibres entering into the composition of this muscle are directed forward for its posterior two-thirds; but on arriving on the shoulder they gradually straighten and become vertical. They are continued, on the margins of the muscle, by aponeuroses which attach it either to the internal surface of the skin or to the fibrous fascie of the superficial muscles. This muscle has, besides, a very remarkable insertion into the humerus, which was noticed by G. Cuvier, in his ‘Lecons d’Anatomie Comparée,’ and which appears to have been omitted, at least so far as Solipeds are in every treatise on Veterinary Anatomy. The following is what we have often observed in this respect :—On reaching the posterior border of the ulnar mass of muscles, the panniculus divides into two superposed layers: one, superficial, is carried to the muscles of the anterior member ; the other, deep, soon terminates by an aponeurosis which is united to the great pectoral muscle, and is bordered at its upper margin by a nacrous aponeurotic band, which penetrates between the thorax and the muscles of the arm to be fixed to the small trochanter. Relations.—By its superficial face, with the skin, to which it closely adheres ; by its deep face, with the great dorsal, the dorsal portion of the trapezius, the abdominal tunic, the great oblique muscle of the abdomen, the great serratus, some external intercostals, the spur vein, and the superficial muscles of the shoulder and arm. Action.— The animal, in contracting this muscle, shakes the whole of the cutaneous integument which covers it; thus preventing insects from alighting on the surface of the body, or tormenting by their bites or stings. Tn the Dog, the panniculus carnosus is prolon over the croup, and is united along the dorso-lumbar spine to that of the opposite side. It is very developed in the Cat. CERVICAL REGION, This region comprises all the muscles grouped around the cervical yertebree—muscles which are conspicuous by their volume and the important part they play in the animal economy. There are described a superior and an inferior cervical. A. Superior Cervical, or Spinal Region of the Neck. This includes seventeen pairs of muscles, which are: the cervical portion of the trapezius,’ rhomboideus, angularis of the scapula, splenius, great complexus, small complexus, transverse spinous of the neck, the six intertransverse muscles of the neck, great oblique muscle of the head, great posterior rectus, and small pos- terior rectus. "These form four superposed layers on each side of the cervical ligament, and occupy the triangular space circumscribed by the upper border of that ligament, the transverse processes of the vertebre of the neck, and the spinous process of the second dorsal vertebra. Preparation.—Place the subject in the second position and dissect in succession the four layers of the region. To study the first layer, which is formed by the cervical portion of the trapezius, remove the skin, cellular tissue, and the fibrous fascia covering that muscle (See fig. 102). The preparation and study of the second layer, com of the rhomboideus, angularis, and splenius, is carried out in two stages. In the first, the trapezium and the mastoido-humeralis is removed, leaving only the cervical insertions * For the description of this muscle, see the Spivat Recton of the back and loins. 188 THE MUSCLES. of the latter muscle ; then the limb is removed by sawing through the scapula beneath the insertions of the angularis and great serrated muscles, as in figure 105, But as neither the cervical or dorsal insertions of the splenius are exposed, it is necessary to proceed to the second part of the a xf removing the rhomboideus, a and the superior extremity of the shoulder. To prepare the third layer, which com- prises the great and small complexus, it is sufficient to excise the splenius, in following the direction of the neck, and to turn upwards and downwards the two portions of the muscle (See fig. 106). Lastly, the deep layer—the transverse spinous, intertransverse, oblique, and posterior straight muscles, as well as the cervical ligament—is exposed by removing the two complexus and the ilio-spinalis muscles (See fig. 104), 1, Bhomboideus. (Figs. 101, 6; 104, 1, 2.) Synonyms.—Described by Bourgelat as two muscles, the proper elevator of the shoulder and the rhomboideus, these were termed by Girard the cervico-subscapularis and dorso-subscapularis, (This is the rhomboideus longus and brevis of Percivall, and the dorso-scapularis and cervico-subscapularis of Leyh.) Form—Situation—Direction.—This muscle has the form of a very elongated triangle, and is situated at the inner aspect of the cervical trapezius and the scapular cartilage, beneath the cervical ligament, whose direction it follows. Fig. 101. ee ———S > ~ : ~ — UY} A . LATERAL VIEW OF THE NECK; SUPERFICIAL MUSCLES, 1, 1, Parotid gland; 2, Sterno-maxillaris and, 14, Its junction with its fellow of the opposite side; 3, 4, Mastoido-humeralis, or levator humeri; 5, Splenius; 6, Rhomboideus; 7, Funicular portion of the cervical ligament, or ligamentum colli; 8, Angularis of the scapula; 9, Supra-, or antea-spinatus; 10, Trapezius ; 11, Infra-, or postea-spinatus; 12, Jugular vein; 13, Subscapulo-hyoideus; 15, Trachea, Structure—Attachments.—It is composed of thick, fleshy fasciculi, the anterior of which are oblique downwards and backwards, the posterior passing directly downwards. These fasciculi are fixed by their superior extremity to the funicular —— of the cervical ligament and the summits of the spinous processes of the four or five dorsal vertebre succecding the MUSCLES OF THE TRUNK, 189 first—/ived insertion ; by their inferior extremity, to the inner aspect of the oye cartilage, where the anterior fasciculi are confounded with those of is. . ions.—Covered by the cervical portion of the trapezius, the seapular cartilage, and the aponeurosis of the great dorsal muscle, the rhomboideus covers the sphenius, which is excavated near its superior border for its reception, as well as the aponeurosis of the anterior small serrated muscle through the medium of a yellow elastic lamina. Action.—It draws the shoulder upwards and forwards. 2. Angularis Muscle of the Scapula. (Figs. 102, 4; 105, 3.) orm Trachelo-subscapularis—Girard. Portion of the serratus magnus _ t. Elevator of the scapula—Cuvier. (Anterior portion of the serratus magnus of Percivall. The levator anguli scapul# of Man.) Situation—Form—Structure.—This is a very strong muscle, situated in front of the shoulder, triangular, flattened on both sides, thin at its superior border, thick behind and below, and almost entirely fleshy. Attachments.—It takes its origin from the transverse processes of the five last cervical vertebra by five distinct portions, which are directed towards the scapula in converging towards each other, and soon join to form a single muscular body, which is inserted into the internal face of the scapula, on its anterior triangular surface. Relations.—This muscle is confounded at its inferior border with the serratus magnus. It is covered by the cervical trapezius, the mastoido- humeralis, and the small pectoral muscle. It covers the splenius, the in- ferior branch of the ilio-spinalis, and the common intercostal muscle. Near its junction with the serratus magnus, its internal face adheres very closely to the transverse processes of the three first dorsal vertebre. Action.—It draws forward the superior extremity of the scapula, while the humeral angle is carried backwards. If the shoulder becomes the fixed point, if can act in the extension or lateral inclination of the neck. 3. Splenius. (Figs. 105, 4,5; 106, 5.) Synonyms.—Cervico-trachelian— Girard. Form—Situation—A considerable muscle, flattened on both sides, , and comprised between the cord of the cervical ligament, the inferior branch of the ilio-spinalis muscle, and the transverse processes of the four first cervical ribs. Structure—The splenius, aponeurotic only at its periphery, is composed of thick fleshy fasciculi which are all directed forwards and upwards, to reach the head and the first cervical vertebra. Aitachments.—It is fixed, by its posterior border, to the lip of the cervical ligament and the summits of the spinous processes of the first dorsal vertebra, by means of an aponeurosis which is continuous behind with that of the small anterior serratus, and confounded, by its inner surface, with that of the great complexus. Its anterior border is cut into four or five digitations which constitute the movable insertions of the muscle: a, The superior digitation is the widest and thinnest, and terminates in an aponeurosis (Fig. 105, 5), which unites it to the mastoid tendon of the small complexus, and passes to the mastoid crest. b. The second joins a very tendon common to the splenius, the small complexus, and the mastoido-humeralis, which tendon is attached to the transverse process of 190 THE MUSCLES. ’ the atlas (Fig. 105, 9). c,d. The two or three others are directly inserted — into the transverse processes of the third, fourth, and fifth cervical vertebre. > Relations.—The splenius is related, outwardly, to the rhomboideus, the — angularis, cervical trapezius, and mastoido humeralis; inwardly, to the two complexus and two oblique muscles of the head; by its inferior border, to a“ “aia margin of the inferior branch of the ilio-spinalis (longissimus orsi). Action.—It extends the head and neck in inclining them to one side. If the two act in concert, the extension is direct. Lol Fig. 102. SUPERFICIAL MUSCLES OF THE NECK AND SPINAL REGION OF THE BACK AND LOLNS, 1, Dorsal trapezius; 2, Great dorsal; 3, Cervical trapezius; 4, Levator anguli scapule; 5, Splenius; 6, Anterior, or superficial portion of the mastoido-hume- ralis ; 7, Its humeral insertion; 7’ Its mastoid insertion ; 8, The thin aponeurosis uniting this insertion to the sterno-maxillary muscle; 8’, Posterior portion of the mastoido-humeralis; 9, Its inferior aponeurosis inserted into the interstice of the long abductor of the arm; 10, Sterno-maxillaris; 11, Subscapulo-hyoideus; 12, Portion of the dermal muscle of the neck; 13, Portion of the great extensor of the fore-arm; 14, Posterior belly of the long abductor of the arm; 15, Great pectoral muscle. } * * Fe 7 i. MUSCLES OF THE TRUNK. 191 4, The Great Complexus. (Fig. 106, 6, 7.) Synonyms.—Dorso-occipitalis—Girard. (Complexus major—Pereivall.) Situation—Direction—Form.—A powerful muscle, included between the internal surface of the splenius and the cervical ligament, whose oblique direction forwards and upwards it follows; it is triangular, flattened on both sides, elongated from before to behind, and divided longitudinally into two ual portions—a posterior and anterior. ture.—The posterior portion (Fig. 106, 6), the most considerable, is aponeurotic at its origin, intersected by linear fibrous bands which obliquely eross its direction, and is formed of fleshy fibres directed forwards. Those which compose the anterior portion (Fig. 106, 7), intermixed with some tendinous fasciculi, are directed upwards, and appear to be inserted into the preceding. It is this difference in the direction of the fibres of the two portions of the great complexus which allows them to be distinguished from one another; the two being only really separated by an interstice near their inferior extremity. Superiorly, the muscle is constricted to form the summit of the elongated triangle it represents, and terminates by a strong tendon. Fized insertions.—The posterior portion derives its origin: 1, From the summit of the spinous processes of the first dorsal vertebree, by a strong aponeurosis which is confounded with that of the splenius and the anterior small serratus; 2, From the transverse processes of the four or five dorsal vertebre which follow the second, by as many aponeurotic digitations united by their margins. The anterior portion is fixed: 1, To the transverse processes of the two first dorsal vertebra, by two tendinous digitations analogous to those of the posterior portion; 2, To the articular tubercles of the cervical vertebre, by the inferior extremity of its fleshy fasciculi. Movable insertion.—The movable insertion of the great complexus is effected through its superior tendon, which is fixed to the posterior face of the occipital protuberance, beside the cervical tuberosity. Relations.—It is covered by the splenius and the small complexus. It covers the cervical ligament, the upper branch of the ilio-spinalis, the trans- verse spinous of the neck, and the oblique and posterior straight muscles of the head. ‘The aponeurotic digitations which attach it to the dorsal trans- verse processes are comprised between the two branches of the ilio-spinalis. The interstice which separates, inferiorly, the two portions of the muscle affords a passage to the superior cervical artery. Action.—It is a powerful extensor of the head. 5. Small Complexus. (Figs. 105, 6,7; 106, 8, 9.) Synonyms.—Dorso-mastoideus— Girard. (Trachelo-mastoideus—Pereicvall.) Situation—Direction.—Situated at the internal face of the splenius, in an oblique direction upwards and forwards, this muscle lies along the anterior border of the great complexus, and follows the inferior branch of the ilio- spinalis, which it appears to continue to the head. Form—Structure—The small complexus is a long muscle, divided into two fleshy, fusiform, and parallel portions—anterior and posterior—which we might strictly consider as two distinct muscles. Both are composed of successive fasciculi, which become longer as they are superficial, and terminate by a tendon at their superior extremity. The tendon of the posterior muscle is flattened, and joins the mastoid aponeurosis of the 192 THE MUSCLES. splenius. That of the anterior muscle is funicular, and receives, before its insertion, a digitation from the splenius (fig. 106, 10), and another from the mastoido-humeralis (fig. 106). ; Fixed attachments.—The two fleshy portions of the small complexus have their fixed insertion in common with the anterior portion of the great com- plexus: 1, On the transverse processes of the two first dorsal vertebra, through the medium of aponeurotic digitations which serve as an origin to the last-named muscle; 2, On the articular tubercles of the cervical vertebra, by the inferior éxtremity of their component fasciculi. Movable attachments.—The terminal tendon of the posterior muscle passes to the mastoid process of the temporal bone. The anterior passes to the transverse process of the atlas. LATERAL VIEW OF THE NECK; MIDDLE LAYER OF MUSCLES, 1, Funicular portion of the cervical ligament; 2, Complexus major; 3, Complexus minor; 4, Rectus capitis posticus major; 5, Rectus capitis posticus minor; 6, Stylo-maxillaris; 7, Carotid artery; 8, Pneumogastric nerve and branch of sympathetic; 9, Longus colli; 10, Recurrent nerve; 11, Inferior scalenus; 12, Spinalis, or transversalis colli; 13, Incision through rhomboideus and trapezius ; 14, Trachea, Relations.—Outwardly, with the splenius; inwardly, with the great complexus and the oblique muscles of the head, The tendon of the posterior fleshy portion is covered by the mastoid aponeurosis of the mastoido- humeralis. Action.—The small complexus inclines to its side the head and upper part of the neck. It also acts as an extensor of the head." 1 Bourgelat has described, by the name of long transversal, the anterior portion of this muscle, and attached it to the posterior portion of the splenius. We do not know where to find one or other of these in the crude description of Lafosse and Vitet. Girard considered them, like ourselves, as a single muscle, which he designates the dorso- mastoideus. Rigot has united them with the anterior portion of the great complexus and the foremost faseiculi of the short transverse muscle (inferior branch of the ilio-spinalis), to make his long transversal; in doing so he has only complicated their description, These two muscular fusciculi, being, to our view, exactly represented, the posterior, at el og se 7 i = ile me oe MUSCLES OF THE TRUNK, 193 sis. - 6. Transverse Spinous Muscle of the Neck. (Fig. 104, 4.) Transversalis colli of Man.) eee eee Short spinous—Bourgelat. Dorso-spinalis—Girard. (Spinalis colli— Situation —Between the great complexus and the cervical ligament, on the lamina of the last five vertebre of the neck. Form—Structure—Attachments.—This muscle, a continuation in the cervical region of that of the back and loins, is generally formed of five thick and short fasciculi, strongly aponeurotic, directed forwards, upwards, and inwards. These fasciculi, attached by their posterior extremities—jixed insertion—to the five last articular tubercles of the cervical region, are fixed by their anterior or superior extremities—movable insertion—into the sixth, fifth, fourth, third, and second spinous processes of that region. ; Relations.—Outwards, with the great complexus; inwards, with the superior branch of the ilio-spinalis and the cervical ligament. By its anterior face, with the lamin of the cervical vertebre and the interlamellar ligaments. Action.— An extensor and flexor of the cervical spine. 7. Intertransversal Muscles of the Neck. (Fig. 104, 9.) Synonyms.—Intercervicals— Girard. (The intertransversalesof Man. Not mentioned by Percival.) : | _ These are six small, short, and very tendinous fasciculi, each of which is doubled into two secondary fasciculi, a superior and inferior. They are lodged in the lateral excavations comprised within the transverse and artic- ular processes of the cervical vertebre, and are carried from one vertebra to another, except from the first to the second. Covered by the cervical attachments of the majority of the muscles of the neck, they cover the vertebre to which they are attached, as well as the vertebral arteries and veins, and the intervertebral foramen. They incline the neck to the side. 8. Great Oblique Muscle of the Head. (Fig. 104, 7.) Synonyms.—Axoido-atloideus—Girard. (Obliquus capitis inferior—Percivall.) Form—Direction—Situation.—A short, thick, and broad muscle, oblique forwards and outwardly, and applied to the superior face of the two first vertebre of the neck. Structure and Atiachments.—Its fibres are nearly all fleshy, parallel to each other, and.longer as they become superficial ; they are attached by their posterior extremity—ixed insertion—to the external face of the spinous process of the axis, and by their anterior extremity—movable insertion—to the superior surface of the transverse process of the atlas, Relations.—Outwards, with the splenius, the great and little complexus ; inwards, with the atlas, the axis, and the atlo-axoid articulation ; above, least, by the small complexus of anthropotomists, we have thought it proper to give it that ag With regard to the muscle generally termed the small pact by veterinary anatomists, following the example of Meckel we will describe it as a portion of the great posterior straight muscle of the head. (Pereivall names Girard’s azoido-occipitalis longus the “ complexus minor,” and his dorso mastoideus the “ trachelo-mastoideus.” Leyh, following Girard, designates the latter muscle the dorso-mastoideus.) 0 em 194 . THE MUSCLES. with the posterior straight muscles of the head; below, with the anterior great straight muscle. Action.—It pivots the atlas on the odontoid process of the axis; itis, therefore, the special rotator of the head. “< Fig. 104, Ey CERVICAL LIGAMENT AND DEEP MUSCLES OF THE NECK. 1, Lamellar portion of the cervical ligament; 2, Funicular portion; 3, 3, The . transversales muscle of the back and loins; 4, 4, Transversales of the neck; 5, | Posterior great straight muscle of the head; 6, Small ditto; 7, Great oblique muscle of the head; 8, Small ditto; 9, 9, Intertransversales of the neck; 10, Anterior great straight muscle of the head; 11, Inferior scalenus muscle; 12, Superior ditto, 9, Small Oblique. (Fig. 104, 8.) Synonyms.—Atloido-mastoideus—Girard. (Obliquus capitis superior—Percivall, Lateral atloido-occipitalis of Leyh, Obliquus superior of Man.) A short, thick, quadrilateral, and strongly aponeurotic muscle. Its fibres are fixed posteriorly—origin—to the lip bordering the transverse process MUSCLES OF THE TRUNK, 195 of the atlas; they are carried from thence forward, upward, and inward, to to be attached—termination—1, To the styloid process of the occipital bones ; 2, To the external surface of that bone, on the imprints which border the mastoid crest posteriorly ; 3, To the mastoid crest itself. This muscle is covered by the mastoid tendon of the small complexus, by the superior gente of the splenius, and that of the mastoido-humeralis. It covers e occipito-atloid articulation, the occipital insertion of the posterior straight muscles of the head, and the origin of the occipito-styloid and digastric muscles. It inclines the head on the atlas, and slightly extends it. 10. Posterior Great Straight Muscle of the Head. (Fig. 104, 5.) yms.—Small complexus and great posterior straight muscle—Bourgelat. Long and short axoido-occipitalis—(Girard. (Complerus minor and rectus capitis posticus major.—Percivall. Leyh gives this muscle the same designations as Girard. It is the rectus capitis posticus major and medius of Man.) Form—Structure—Situation.—Elongated, prismatic, easily divisible into two fasciculi—one superficial, the complexus minor of Bourgelat (and Per- civall) ; the other deep, the great posterior straight muscle of Bourgelat (and. the rectus capitis posticus major of Percivall)—entirely fleshy, and formed ; parallel fibres, this muscle is lodged, with the small posterior straight i ‘muscle, in a triangular space circumscribed by the cord of the cervical liga- ment and the internal border of the oblique muscles. Attachments.—It is attached, by its superior extremity, to the whole extent of the uneven lip which terminates the spinous process of the axis— insertion. Its anterior extremity is insinuated beneath the small oblique muscle, and is fixed to the occipital bone, behind the superior insertion of the great complexus, whose tendon receives some of the fibres of the superficial fasciculus—morable insertion. Relations.—Above, with the great complexus; below, with the small straight muscle ; inwards, with the cord of the cervical ligament and the analogous muscle of the opposite side ; outwards, with the oblique muscles. Action.—This muscle, a Gongener of the great complexus, aids in extending the head. 11. Small Posterior Straight Muscle. (Fig. 104, 6.) Synonyms.— Atloido-occipitalis—Girard. (Rectus capitis posticus minor— Percivall. The Atloido-oceipitalis superior of Leyh. The rectus capitis posticus minor of Man.) A very small, wide, and triangular muscle, flat above and below, and lying re: immediately upon the fibrous capsuic vf the occipito-atloid articulation. It 3 is attached, posteriorly, to the superior face of the atlas—origin ; in front, to the external surface of the occipital bone, below the preceding muscle, whose U action it shares. _ B. Inferior Cervical or Trachelian Region. i, The muscles composing this region are situated in front of the cervical ___-yertebrw, and are, for the most part, grouped around the trachea, which they | envelop as in a kind of sheath. They are eleven in number: the cuticular muscle of the neck, the mastoido-humeralis, sterno-mazillaris, sterno-hyoideus, sterno-thyroideus, omo- or subscapulo-hyoideus, the great and small anterior straight muscles of the head, the small straight lateral muscle, the scalenus, and the long muscle of the neck, o 2 196 THE MUSCLES. Preparation.—1. Place the animal in the first position. 2. Remove the skin of this region, in order to expose and study the cuticular muscle, 3. Remove that musele and the parotid gland to prepare the mastoido-humeralis,' the stylo-maxillaris, sterno- hyoideus, and sterno-thyroideus, 4. Transversely cut through the mastoido-humeralis near the angle of the shoulder, and isolate it from the subscapulo-hyoideus to expose this muscle; taking care to preserve the jugular vein and parotid gland, in order to study their relations with it. 5. Remove the fore limbs; open the thoracic cavity by sa “7S through the eight first ribs near their superior extremity ; take out the viscera contai = in this cavity, as well as the trachea, esophagus, pharynx, and larynx, to expose the ’ long muscle of the neck, the scalenus, and the straight muscles of the head, 1. Subcutaneous Muscle of the Neck. (Figs. 102, 12; 114, 1.) ‘ Synonyms.—It has been described by Bourgelat, and the majority of veterinary anatomists who have followed him, as two muscles: the cuticularis of the neck and the face. (Percivall includes this muscle in his description of the panniculus carnosus.) This is a membraniform expansion, partly fleshy, partly aponeurotic, which covers the muscles of the neck, the intermaxillary space, and the face. The fleshy fibres form, in front of the neck, a thin band, whichis united, __ through the medium of a fibrous raphé, to that of the opposite side. This — . band is in contact with the sterno-maxillary, sterno-hyoid, subscapulo-hyoid, | and sterno-thyroid muscles, as well as the jugular vein: enveloping them ; all as in a sort of gutter. It gradually thins from below upwards, in such a ' manner that around the upper part of the throat it is only composed of some ; scattered fibres. In the intermaxillary space, and on the expanding borders of the maxillary branches, the fleshy fibres appear again of a certain thickness, but only to become attenuated on the external surface of the \ cheeks. a These fleshy fibres leave the anterior prolongment of the sternum* and intermediate middle raphé of the two muscles, and directing their course outwards art ~)Wwards, soon become confounded with the aponeurosis. The latter, extremely thin, is spread over the mastoido-humeralis, the superior cervical muscles, parotid region, and the cheeks, and is finally attached to the zygomatic crest. On arriving near the commissure of the lips, the cuticular muscle is united to the alveolo-labialis (or buccinator muscle) by a fleshy fasciculus named, in Man, the risorius santorini (Fig. 110, 24). The cuticularis colli braces the muscles it covers during their contraction and pulls backwards the commissures of the lips. We doubt very much ‘ whether it has, in the cervical region at least, any action on the skin, for it . adheres but very slightly to its inner surface. | 2, Mastoido-humeralis. (Figs. 102, 105, 106, 114.) Synonyms.—The muscle common to the arm, neck, and head—Bourgelat. Re senting the cleido-mastoid, and the clavicular portions of the trapezius and deltoid of 1 The mastoido-humeralis may be dissected at the same time as the trapezius, the subject being placed in the second position, This conveniently permits the superior insertions of the muscle to be studied. (See fig. 102). 2 It will be seen, on referring to figure 114 and its legend, that we restore to the cuticular muscle of the neck the sternal band attributed until now to the mastoido- . humeralis. ‘These are the considerations which induce us to make this modification: ‘1, This band is not distinct from the cuticularis of the neck ; a separation between the two muscles can only be artificially obtained. 2, In dissecting this band with care, we can see that its fibres, like those of the cuticularis, are not mixed with those of the mastoido-humeralis (superficial portion) ; they pass along the external surface of that muscle, to which they intimately adhere, it is true, but they can easily be separated, and are continuous with the aponeurosis of the first. / MUSCLES OF THE TRUNK. 197 Man, and the trachelo-acromialis peculiar to quadruped mammals'—G. Cuvier, ‘ Lecons dAnatomie Com , 2nd edition. (This is the muscle which Percivall names the levator humeri. The above is the designation given to it by Girard and Chauveau. Leyh gives it the same designation as Bourgelat.) Extent—Situation—Direction—Composition.—This muscle extends from the summit of the head to the inferior part of the arm, and is applied to the scapulo-humeral angle at the side of the neck, in an oblique direction down- wards and backwards. It is composed of two portions lying longitudi- nally and somewhat intimately united, and distinguished into anterior and _ Form—Structure—Attachments.—A. The anterior or superficial portion (Fig. 106, 6) constitutes a long fleshy band, which appears to be united, by its anterior border, to the cuticular muscle of the neck. Its superior extremity, thin and wide, is attached to the mastoid process and crest by-an aponeurosis (Fig. 102, 7), which is united, in front, to the tendon of the sterno-maxillaris by a very thin cellulo-aponeurotic fascia. Its inferior ex- tremity, thicker than the superior, is inserted by means of a very short aponeurosis into the humerus, on the salient border descending from the deltoid imprint, and which limits, in front, the furrow of torsion on the body of that bone (Fig. 102, 7). B. The posterior or deep portion (Fig. 102, 9) is a second muscular band, shorter and stronger than the preceding. It is attached, above, to the transverse processes of the first four cervical vertebree by as many fleshy bands (Fig. 102, 8’), which cover the superficial portion. The upper digitation, given off to the atlas, is united to the tendon common to the small complexus and splenius (Figs. 105, 9; 106, 9’, 10,11). The inferior extremity of this portion of the muscle widens on the scapulo-humeral angle, which it enyelops in becoming closely united to the anterior portion, terminating with it on the humerus. An aponeurosis, which is confounded with that of the trapezius, and sends off a septum into the interstice between the two portions of the long abductor of the arm, concurs to fix this extremity by spreading over the muscles of the arm. Relations.—It is covered, near its mastoid insertion, by the parotid gland and the cervico-auricularis muscles ; for the remainder of its extent, by the aponeurosis of the cuticularis colli, from which it is separated by a thin ~ fascia continuous with that which extends over the trapezius. It covers the splenius, the small complexus, the oblique muscles of the head, subscapulo- hyoideus (to which.it adheres intimately), the digastricus, long flexor of the head, the angularis, scalenus, small pectoral, supra- and infraspinatus, the long abductor of the arm, and the coraco-radialis. 1 At first sight we might hesitate to admit that this muscle is formed of such varied and complicated elements as are enumerated above. Nevertheless, it is a scientific fact ; and we will give a demonstration, as simple as it is clear, that such is the case—the idea we owe to J. F. Meckel. If we take the Dog, for example, and suppose it to be possessed of a clavicle extending from the anterior extremity of the sternum to the acromion: this clavicle would cut, transversely, the inferior portion of the mastoido- humeralis, which would thus be divided into two portions, a superior and an inferior. The first, extending from the clavicle to the mastoid process, on this side, and on the other to the mastoid crest, as well as to the cervical ligament, where it is confounded with the trapezius, would exactly represent the ¢lavicular portion of the latter muscle, and the cleido-mastoideus. With resect to the inferior portion, it perfectly resembles, by its atiachments, the clavicular portion of the deltoid. But, on the contrary, if we suppose pacecrived of a clavicle, the three muscular fasciculi indicated, in becoming con- with each other, would form the mastoido-humerslis of the Dog, minus the posterior portion, or the trachelo-acromialis, which is not represented in Man. 198 THE MUSCLES, Action.— When the superior is the fixed point, it carries the entire anterior limb forward. This muscle, therefore, plays a very important part in locomotion; as it is called into action when the animal raises the fore-limb in getting over the ground. If the fixed point of the musele is the limb, it inclines the head and neck to one side. 3. Sterno-mawillaris, (Figs. 102,10; 114, 4.) Synonym.—The sterno-mastoideus of Man and a large number of the lower animals. Form—Structure—Situation—Direction—Attachments,—A long narrow muscle, almost entirely fleshy, and terminated at its upper extremity by a flat- tened tendon; situated in front of the neck, beneath the cuticularis, and parallel to the anterior border of the superficial portion of the mastoido- humeralis, from which it is separated by a space that lodges the jugular vein; attached, inferiorly, to the cariniform cartilage of the sternum— insertion ; and superiorly—movable insertion—to the curved portion of the posterior boider of the maxillary bone by its terminal tendon. Relations.—The muscle is covered by the cuticularis colli, and the parotid gland. It covers the trachea, the subscapulo-hyoideus, sterno- — hyoideus, sterno-thyroideus, and the maxillary gland. Its external border, parallel to the anterior border of the mastoido-humeralis, forms with it a longitudinal depression termed the jugular furrow, because it lodges the vein of that name. Its inner border is intimately united, in its lower third, to that of the opposite muscle. Action.—It directly flexes the head, when acting in concert with its © congener; but alone it turns it to one side. Lafosse and Rigot have wrongly considered this muscle as a depressor of the lower jaw. Bourgelat has correctly stated that it cannot move this jaw independently. (Percivall says that the pair will assist in opening the mouth; and Leyh asserts that when the mouth is closed, each muscle will act as a flexor to the head.) _ 4, Sterno-hyoideus.—5. Sterno-thyroideus. (Fig. 114, 6, 7.) (Synonym.—The sterno-thyro-hyoideus of Percivall.) Form—Structure —Situation—Attachments.—Small, ribbon-shaped, long, and slender muscles ; digastric ; situated in front of the trachea ; confounded at their inferior extremity and united to those of the opposite side, so as to form a single fasciculus which is attached to the cariniform cartilage of the sternum—fixed insertion ; isolated from each other above the tendon which makes them digastric, and terminating by their superior extremity —movable insertion : the first, on the inferior surface of the body of the hyoid bone in common with the subscapulo-hyoideus ; the second, on the posterior border of the thyroid cartilage. Relations,—Covered by the sterno-maxillaris and the cuticularis muscle, they cover the anterior face of the trachea. Aclion.—Depressors of the hyoid bone and larynx. 6. Omo-hyoideus or Subscapulo-hyoideus. (Figs. 102,11; 114, 5.) Synonyms.—Hyoideus—Bourgelat. (Subscapulo-hyoideus—Percivall.) Form—Structure —Situation —Direclion.—This muscle forms a thin and wide band, almost entirely fleshy, oblique forwards and upwards, extending from the scapulo-humeral angle to the intermaxillary space, and applied to the side of the trachea, whose direction it slightly crosses, : i lag —_ ; oe ee boll MUSCLES OF THE TRUNK. 199 Attachments.—It derives its fixed insertion from the inner surface of the subscapularis, by an aponeurosis which is detached from that covering the latter muscle. Its movable insertion is into the body of the hyoid bone, in becoming confounded with the sterno-hyoideus, and in being intimately united to the muscles of the opposite side. Relations.—Outwardly, with the subscapularis, supraspinatus, small pectoral, mastoido-humeralis—which closely adheres to it, the jugular vein, the sterno-maxillaris, and the cuticularis. Inwardly, with the scalenus, the large anterior straight muscle of the head, the main trunk of the carotid artery and the nerves accompanying it, the trachea, thyroid gland, and the ' inferior face of the larynx. The jugular vein is entirely separated from the carotid artery by this muscle in the upper half of the neck. Action.—It is a depressor of the hyoid bone and its appendages. 7. Great Anterior Straight Muscle of the Head. (Figs. 104 and 105, 10; . 106, 13.) Synonyms.—Long flexor of the head—Bourgelat. Trachelo-suboccipitalis— Girard. (Rectus capitis anticis major—Percivall. Trachelo-oceipitalis—Leyh.) Form—Structure—Situation—Direction— A long, flat muscle, fascicu- lated in its posterior half, terminated in a tendinous cone at its anterior extremity, and passing along the first cervical vertebra in front. Aitachments—Behind, to the transverse processes of the third, fourth, and fifth cervical vertebre by as many fleshy digitations, the most inferior of which are the longest—fixed insertion. In front, into the imprints on the body of the sphenoid bone and the basilar process, by its terminal tendon— movable insertion. Relations —Outwardly, with the mastoido-humeralis, the subscapulo- hyoideus, and the small anterior straight muscle. Inwardly, with the long muscle of the neck and the muscle of the opposite side. In front, with the common carotid, the nerves accompanying this artery, and the guttural pouch, which lines it near its movable insertion. Behind, with the great oblique muscle of the head and the occipito-atloid articulation. Action.—It either directly flexes the head or carries it to one side, according as it acts alone or with its fellow of the opposite side. 8. Small Anterior Straight Muscle of the Head. Synonyms.—Flexor capitis brevis—Bourgelat. Atlvido-suboccipitalis— Girard. (Rectus capitis anticus minor—Percivall. Atloido-occipitalis inferior—Leyh.) A small, entirely fleshy, prismatic fasciculus, lying to the external side of the preceding muscle; attached, posteriorly, to the inferior face of the body of the atlas ; in front, to the body of the sphenoid bone and the basilar process, beside the great anterior straight muscle. It is covered by the aeerarel pouch, and covers the occipito-atloid articulation. It concurs in xing the head. 9. Small Lateral Straight Musele. Synonyms.—Flexor capitis parvus—DBourgelat. Atloido-styloideus—Girard, (Obli- quus capitis anticus—Percivall. ‘The rectus capitis lateralis of Man.) Yet smaller than the preceding, and prismatic and entirely fleshy, like it this muscle lies on the side of the occipito-atloid articulation ; it is attached to the atlas, outside the small anterior straight muscle—jized insertion ; and to the inner face of the styloid process of the occipital bone—movable insertion. It is the congener of the two anterior straight muscles of the head. 200 THE MUSCLES. 10. Scalenus. (Figs, 104, 105, 106.) Synonyms.—Costo-tracheleus—Girard. (Scalenus anticus and posticus of Man.) - Situation— Direction—Composition.—Deeply situated at the inferior 4 part of the neck, in an oblique direction downwards and backwards, this = miele comprises two portions of unequal dimensions, placed one above another. Form—Structwre—Attachments.— A, The superior portion (scalenus posti- cus of Man), the smallest, is composed of three or four fizehy eosealt attached by their extremities to the transverse processes of the last three or four __ cervical vertebra. The last terminates at the superior extremity of the first rib. B. The inferior (scalenus anticus of Man), the most considerable, is flattened on both sides, thick and wide posteriorly, thin and narrow anteriorly, and is composed almost entirely of fleshy fibres which are longest as they are inferior. It is attached: 1, To the transverse processes of the last four cervical vertebre by short fasciculi scarcely distinct from one angther, the first of which is crossed by the last digitation of the fe anterior straight muscle; 2, To the anterior border and external face of the first rib, where all its fibres end. = Relations.—The scalenus responds: by its external face, to the sub- scapulo-hyoideus, mastoido-humeralis, and the sterno-prescapularis; by its internal face, to the longus colli, trachea, common carotid artery and its accompanying nerves, and—on the left side only—to the cesophagus; by its - inferior border, to the jugular vein, The two portions of the scalenus are - separated from one another, in front of the first rib, by an interspace traversed by the nerves of the brachial plexus. Action When the first rib is the fixed point, this muscle either directly flexes the neck or inclines it to one side. When the neck is the fixed point, it draws forward the first rib and fixes it in this position during the dilatation of the chest, in order to aid the inspiratory action of the external intercostal muscles, 11. Long Muscle of the Neck. a Synonyms.—Flexor longus colli—Bourgelat. Subdorso-atloideus—Girard. (Longus colli—Percivall. Dorso-atloidews—Leyh.) Situation—Composition.—A single and considerable ‘muscle, immediately covering the inferior aspect of all the cervical and the first six dorsal vertebre, and composed of two lateral portions which are united on the median line, and constitute, in certain animals, two distinct muscles, Structure—Attachments.—Each lateral portion of the longus colli is composed of a succession of very tendinous fasciculi. The most posterior of these is attached to the inferior face of the bodies of the first six dorsal vertebre, and proceeds directly forward to reach the inferior tubercle of the sixth cervical vertebra, into which it is inserted by a strong tendon. The other fasciculi, less considerable, and confounded outwardly with the inter- transversales of the neck, are carried from one cervical vertebra to another, and are directed forwards, upwards, and inwards, in converging towards those of the opposite side. They are attached successively: outwardly, to the transverse processes of the last six cervical vertebre; inwardly, to the— inferior ridge on the bodies of the first six. The most anterior fasciculus passes to the inferior tubercle of the atlas, into which it is inserted by a LD 3 a) : & MUSCLES OF THE TRUNK. 201 tendon common to it and the fasciculus of the oppasite side, and which receives the most superficial fibres of the three or four preceding fasciculi. 5 ES De awe Se ” SP- P 212 THE MUSCLES. 1. Iliac Fascia or Lumbo-iliae Aponeurosis. (Fig. 108, a.) rae A This is a very resisting fibrous expansion, covering the great and iliae _ psoas muscles. Attached, inwardly, to the tendon of the small psoas, out- | wardly to the angle and external border of the ilium, this aponeurosis, as it extends forwards over the great psoas, degenerates into cellular tissue. Behind, it also becomes attenuated in accompanying the two muscles it covers until near their insertion into the internal trochanter of the femur. Its external or inferior face receives, posteriorly, the insertion of the crural arch, and gives attachment to the long adductor of the leg; for the re- mainder of its extent, it is covered by the peritoneum. 2. Great Psoas Muscle. (Fig. 108, 1.) Synonyms.—Sublumbo-trochantineus—Girard. Psoas—Bourgelat. (Lumbo-femoral— Leyh. Psoas magnus—Percivall.) Form—Situation.—This is a long muscle, flattened above and below at its anterior extremity, prismatic in its middle, and terminated in a cone at its | posterior extremity. It lies beneath the transverse processes of the lumbar __ vertebra. Structure—Almost entirely fleshy, this muscle is formed of fasciculi, very delicate in texture, directed backwards, and long in proportion to their superficial and deep situation. They all converge to a tendon which is enveloped by the iliac muscle, and is confounded with it. Alttachments.—The great psoas is attached: 1, By the anterior extremity of its fleshy fasciculi to the bodies of the last two dorsal and the lumbar vertebrx, except the hindermost, and to the inferior face of the two last ribs and the transverse processes of the lumbar vertebre ; 2, By its posterior tendon to the internal trochanter, in common with the psoas iliacus. Relations.— Below, with the pleura, the superior border of the diaphragm, the lumbo-iliac aponeurosis, which separates it from the peritoneum and the abdominal viscera situated in the sublumbar region; above, with the two last internal intercostals, the quadratus, and the intertransversales muscles; inwardly, with the small psoas and the internal branch of the iliac psoas; outwardly, for its posterior third, with the principal branch of the latter muscle. f Action.—A flexor and rotator of the thigh outwards when its fixed point is the loins, this muscle also flexes the lumbar region when the thigh is ; a fixed point. It is, therefore, one of the agents which determine the arching of the loins, and which operate, during exaggerated rearing or prancing, in “bringing the animal into a quadrupedal position again. 3. Iliac Psoas Muscle. (Fig. 108, 3, 4.) i Synonyms.—Llio-trochantineus—Girard. (Leyh divides this muscle into two tions, which he describes as the great and middle ilio-femoralis, Iliacus—Percivall.) - Form—Situation—Direction.—This is a very strong, thick, and prismatic muscle, incompletely divided into two unequal portions by the groove for the reception of the tendon of the great psoas : an external portion, somewhat considerable in size; and an internal, small. These two muscular portions lie at the entrance to the pelvis, on the inner face of the ilium, in an oblique direction downwards, backwards, and inwards. ; Structure.—It is almost entirely fleshy. The fasciculi forming it are MUSCLES OF THE TRUNK, 213 out in front, and collected behind, where they become slightly fibrous, and unite with the tendon of the great psoas. Aittachments.—It has its fixed insertion on the whole of the iliac surface, on the external angle of the ilium, the sacro-iliac ligament, and the ilio- Fig. 108, MUSCLES OF THE SUBLUMBAR, PATELLAR, AND INTERNAL CRURAL REGIONS 1, Psoas magnus; 1’, Its terminal tendon; 2, Psoas parvus; 3, Iliac psoas; 4, Its small internal portion; 5, Muscle of the fascia lata; 6, Anterior straight muscle of the thigh ; 7, Vastus internus; 8, Long adductor of the leg; 9, Short adductor of the leg; 11, Pectineus; 12, Great adductor of the thigh; 12’, Small adductor of the thigh; 13, Semimembranosis; 14, Semitendinosis.—a, Portion of the fascia iliaca; B, Portion of the membrane reflected from the aponeurosis of the abdominal great oblique muscle, forming the crural arch (Poupart’s ligament); c, Pubic tendon of the abdominal muscles; D, Origin of the pubio-femoral ligament. ek ee ero + »- or pectineal crest. Its movable insertion is into the small internal trochanter, in common with the great psoas. Relations —Above, with the ilium ; below, with the iliac fascia and the long adductor of the leg; outwardly, with the muscle of the fascia lata and . =a. 214 THE MUSCLES. the origin of the anterior straight muscle of the thigh, from which it is separated by a space filled with fat; inwardly, with the crural vessels. It passes between the vastus internus and the pectineus, to reach the trochanter. Actions.—It is a flexor and rotator outwards of the thigh. 4. Small Psoas Muscle, (Fig. 108, 2.) Synonyms.—Psoas of the loins—Bourgelat. Sublumbo-pubialis, or sublumbo-iliacus, according to Girard. (Psoas parvus—Percivall, The lombo-iliacus of Leyh.) Situation—Form—Structure.— Placed at the inner side of the great psoas, very much elongated, and semipenniform in shape, this muscle is terminated behind by a flattened tendon, and is composed of fleshy fibres, the longest of which are anterior. These fasciculi are all directed backwards and*outwards to gain the tendon. Attachments.—1, To the bodies of the three or four last dorsal, and to all the lumbar vertebre, by the anterior extremity of its fleshy fibres; 2, To the ilio-pectineal eminence and the lumbo-iliac aponeurosis, by the posterior extremity of its tendon. Relations.—By its inferior face with the pleura, the superior border of the diaphragm, the aorta or posterior vena cava, and the great sympathetic — nerve; by its upper face, with the psoas magnus. It is traversed, near its vertebral insertions, by numerous vascular and nervous branches. Actions.—It flexes the pelvis on the spine, when the loins are the fixed point ; but should the pelvis be fixed, it arches or laterally inclines the lumbar region. It is also the tensor muscle of the lumbo-iliac aponeurosis, Fig. 109. 5, Square Muscle of the Loins. (Fig. 109, 1.) 8 yms. — Sacro-costalis — Girard. (Sacro-lumbalie —Pereivall, Quadratus lumborum of Man.) Situation — Form— Structure —Attachments.—This muscle is comprised between the trans- verse processes of the lumbar region and the great psoas, and is elongated from before to be- hind, flattened above and below, and divided into several very tendinous fasciculi. The prin- cipal fasciculus, situated out- wardly, takes its origin from the sacro-iliac ligament, near the angle of the sacrum, and ex- tends directly forward to gain the posterior border of the last rib, after being attached by its upper face to the summits of the transverse processes of the lum- 1, Quadratus lumborum ; 2, 2, Intertransversales; pay yertebre. The other fasci- 3, Small retractor muscle of the last rib—a de- a ahtiaas of the abdomen, culi are longer as they are an- samedi alg ae terior; they leave the internal border of the first, and are directed obliquely forward and inward, to be DEEP MUSCLES OF THE SUBLUMBAR REGION, F to a envelop; the fourth is designated the ischio-coccygeus. MUSCLES OF THE TRUNK, 215 fixed into the transverse processes of the majority of the lumbar vertebra, and the inner face of the two or three last ribs. Relations.—By its upper face, with the intertransversales, the small retractor of the last rib, and the fibrous fascia which unites that muscle to the small oblique of the abdomen. By its inferior face, to the great psoas. Actions}—It draws the last ribs backwards, and inclines the lumbar spine to one side. 6. Intertransverse Muscles of the Loins. (Fig. 10), 2, 2.) (Synonym—Intertransversales lumborum—Percivall.) : These are very small flat muscles which fill the intervals between the transverse processes of the lumbar vertebre. The muscular fibres entering into their composition are mixed with tendinous fibres, and are carried from the anterior border of one transverse process to the posterior border of the other. They respond, by their superior face, to the ilio-spinalis (longissimus dorsi), and by their inferior face to the quadratus, as well as the psoas magnus. They act by inclining the lumbar region to one side. DIFFERENTIAL CHARACTERS OF THE MUSCLES OF THE SUBLUMBAR REGION IN OTHER THAN SOLIPED ANIMALS, In Ruminants and the Pig, the muscles of this region so closely resemble those of ey Apes that a special description is unnecessary, the Dog, the great psoas is little developed, and only commences at the third, or even the fourth lumbar vertebra; the iliac psoas is very slender, particularly in its external portion ; otherwise it is scarcely distinct from the great psoas, with which it may be said to form one muscle; the small psoas is relatively larger than the great; it is not prolonged into the pectoral cavity, and its anterior extremity is confounded with the quadratus lumborum, which is longer and stronger than in all the other animals, COMPARISON OF THE SUBLUMBAR MUSCLES OF MAN WITH THOsE OF ANIMALS. In human anatomy, by the names of psoas and iliacus are described the great psoas and iliac psoas of animals. The psoas magnus of MAN is distinguished from that of sa by its superior insertions, which do not go beyond the last dorsal vertebra. small psoas is often absent; when present, it is attached, above, to the bodies of the twelve dorsal vertebrx, below, to the ilio-pectineal crest. The intertransversales have been studied with the muscles of the back. The > dratus of the loins, classed by anthropotomists with the abdomiual muscles,—is* inctly divided into three series of fasciculi: ilio-costal fusciculi, which pass from the upper border of the ilium to the twelfth rib; lwmbo-costal fasiculi, passing from the transverse of the three or four last lumbar vertebre to the twelfth rib, and ilio- lumbar fasciculi, going fromthe iliac crest to the posterior face of the transverse processes of all the Jumbar vertebrae. , COCCYGEAL REGION. This region is composed of four pairs of muscles destined for the movements of the tail: three, named the sa geal, are a longitudinally around the coccygeal vertebre, wile they completely 1. Sacro-coccygeal Muscles. (Fig. 131, 1, 2, 3.) These three muscles are inclosed, with those of the opposite side, in a common aponeuroctic sheath which is continuous with the inferior ilio-sacral and sacro-ischiatic ligaments. They commence on the sacrum, are directed backwards and parallel with the coccyx, gradually diminishing in thickness, and are decomposed into several successive fasciculi terminated by small ™~ 216 THE MUSCLES. tendons, which are inserted into each of the coccygeal bones. With regard to their situation, these muscles are distinguished as sacro-coccygeus superior, sacro-coccygeus inferior, and sacro-coceygeus lateralis. a. Sacro-coccygeus Superior. (Synonym.—Erector coccygis— Percivall.) The fasciculi which form this muscle take their fixed insertion either from the summits and sides of the three or four last processes of the super- sacral spine, or from the coccygeal vertebre themselves. ‘I'he tendons through which they effect their movable insertion into these vertebra are always very short. This muscle, covered by the coccygeal aponeurosis, in turn covers the vertebra it is designed to move. It responds: inwardly, to the analogous muscle of the opposite side ; outwardly, to the lateral sacra-coccygeus, and, near its anterior extremity, to a very strong aponeurotic expansion which separates it from the transverse spinous muscle. It directly elevates the tail, or pulls it to one side, according as it acts in concert with its fellow or singly. . ; b. Sacro-coceygeus Inferior. (Synonym.—Depressor coceygis—Percivall.) This muscle is thicker than the preceding; its constituent fasciculi ~ jake their origin from the inferior surface of the sacrum, towards the third vertebra, and from the internal face of the sacro-ischiatic ligament and the coccygeal bones. It readily divides into two parallel portions, which Bourgelat has described as two separate muscles. The fasciculi of the internal portion are inserted, by their posterior extremity, into the inferior face of the first coccygeal vertebre. Those of the external portion are all furnished with strong superficial tendons, nearly all of which are for the bones of the tail. This muscle responds: outwardly, to the ischiatic ligament, the ischio- coccygeus and coccygeal aponeurosis ; inwardly, to the muscle of the opposite side, and to the coccygeal attachment of the rectum; above, to the sacrum, the bones of the tail, and the lateral muscle; below, to the rectum and the coccygeal aponeurosis, It either directly depresses the tail or inclines it to one side. c. Sacro-coccygeus Lateralis. (Synonym.—Curvator coceygis—Percivall. ) This muscle may be considered as the transverse spinous of the region; indeed, it is confounded with that muscle of the back and loins by its anterior extremity, and appears to continue it to the inferior extremity of the tail. The fasciculi composing it have their origin from the spinous processes of the last lumbar vertebre, through the medium of the transverse spinous, and from the coccygeal bones. The tendons terminating these fasciculi are deep and not very distinct. It responds; outwardly, at the posterior extremity of the ilio-spinalis, to the inferior ilio-sacral ligament and the coccygeal aponeurosis; inwardly, to the transverse spinous and the coccygeal vertebre ; above, to the superior muscle; below, to the inferior muscle, from which it is nevertheless =* i MUSCLES OF THE HEAD. 217 separated by several small independent muscular fasciculi, which are carried from one coceygeal vertebra to another. (Leyh designates these the inter- transversales of the tail.) It inclines the tail to one side. : ’ 2. Ischio-coceygeus. (Fig 131, 41.) {Synonym.— Compressor coceygis—Percivall.) A small, thin, wide, and triangular muscle, situated against the lateral wall of the pelvis, at the internal face of the sacro-ischiatic ligament. It is attached, by an aponeurosis, to that ligament and to the ischiatic crest; it is then directed upwards to be fixed, by its muscular fibres, to the side of the last sacral vertebra and the first two coccygeal bones. It is related, outwardly, with the sacro-ischiatic ligament, and inwardly to the lateral sacro-coccygeus and the rectum, , It depresses the entire caudal appendage. REGION OF THE HEAD. |The head comprises a large number of muscles, of which only those covering the bones of the face, and those which move the lower jaw and os hyoides, will be described. The others will be studied with the apparatus to which they belong. A. Facial Region. This.region includes those muscles of the head which form a part of the framework of the lips, cheeks, and nostrils: that is, all those which are grouped around the face, properly called. Authors are far from being unanimous with regard to the nomenclature and description of these muscles. Girard zooged eleven, to which he gave the following names: labialis, alveolo-labialis, zygomatico-labialis, lachrymo-labialis, supernaso-labialis, super- mazxillo-labialis, supermaxillo-nasalis magnus, su villo-nasalis parvus, transversalis nasi, maxillo-labialis, mento-labialis. To these eleven muscles, three of which are single, two others are added; these were described by Bourgelat as the middle (intermediate) anterior and middle (intermediate) pos- terior muscles, which Girard wrongly considered as belonging to the labial. ' 1. Labialis, or Orbicularis of the Lips. (Fig. 110, 27.) (Synonym.—Orbicularis oris—Percivall.) Preparation.—Remove with scissors the skin covering the two portions of this muscle ; afterwards the buccal mucous membrane and subjacent glands within the lips, to expose its internal face. The labialis, disposed as a sphincter around the anterior opening of the mouth, is regarded as the intrinsic muscle of the lips, and is composed of two portions or fasciculi, one for the upper, the other for the lower lip. United to each other at the commissures of the mouth, and confounded with the superficial layer of the alveolo-labialis, which they appear to continue, these two muscular portions also receive a large portion of the fibres belonging to the majority of the extrinsic muscles, such as the supermaxillo- nasalis magnus and supernaso-labialis. The orbicularis is not attached to the neighbouring bone ; its component fibres affecting a circular form, have, consequently, neither beginning nor ending, except in being continuous with other fibres. The internal face of the superior fasciculus responds to a layer of salivary 218 THE MUSCLES. glands, which in part separate it from the buccal mucous membrane. The external, covered by the skin, adheres to it in the most intimate manner, and is found isolated from it only on the median line, at first by the aponeurotic expansion of the supermaxillo-labialis, then by a musculo-fibrous layer analogous to that which forms the mento-labialis, By its internal face, the inferior fasciculus likewise responds to the buccal mucous membrane, and to some salivary glands. By its external face, it Fig, 110, SUPERFICIAL MUSCLES OF THE FACE AND HEAD. 1, Temporo-auricularis externus, or attollens maximus; 2, Levator palpebra, or corrugator supercilii; 3, Temporo-auricularis internus, or attollens posterior ; 4, 5, Zygomatico-auricularis, or attollens anterior; 6, Orbicularis palpebrarum ; 7, Parotido-auricularis, or deprimens aurem; 8, Parotid gland; 9, Temporal, or subzygomatic vein; 10, Ditto, artery; 11, 12, Superior and inferior maxillary nerves; 13, Fascia of the masseter muscle; 14, Nasal bones; 15, Supernaso- labialis, or levator labii superioris alaque nasi; 16, Supermaxillo-labialis, or nasalis longus labii superioris; 17, External maxillary or facial artery; 18, Facial vein; 19, Supermaxillo-nasalis magnus, or dilatator naris lateralis; 20, Superior maxillary nerve; 21, Zygomatico-labialis, or zygomaticus ; 22, Parotid, or Stenon’s duct; 23, Masseter; 24, Alveolo-labialis, or buccinator ; 25, Super- maxillo-nasalis parvus, or nasalis brevis labii superioris; 27, Labialis, or orbicu- laris oris; 28, Maxillo-labialis, or depressor labii inferioris; 29, Mento-labialis, or levator menti. forms an intimate union with the cutaneous integument, like the superior fasciculus. This muscle plays the part of a constrictor of the anterior opening of the mouth, and has complex functions to perform in suction, the prehension of food, and in mastication. 2. Alveolo-labialis. (Fig. 110, 24.) Synonyms.— Molaris externus et internus—Bourgelat. (Buccinator—Poreivall. Leyh divides this muscle into two portions; its superficial plane he designates the buccinator, and the deep plane the molaris.) Preparation.—Proceed to the ablation of the masseter ; dissect the external surface of the muscle, taking care of the risorius Santorini and zygomaticus, which are confounded — with it. Then divide it in the middle, as far as the commissure of the lips; turn down each strip on the jaws, and remove the mucous membrane, in order to study the inner face of the muscle and the attachments of the superficial plane to the bones. a ~ P ania a = © MUSCLES OF THE HEAD. 219 Situation—Form.—Situated on the sides of the face, partly concealed by the masseter muscle, and applied to the mucous membrane of the cheeks, the alveolo-labialis is a flat, thin muscle, elongated in the direction of the head, and formed of two superposed planes. Extent—Siructure—Attachments.—T he deep plane, the longest and least wide, is narrower dt its extremities than its middle, and is formed of strongly eurotic muscular fasciculi, which are attached, posteriorly: 1, To the ier tuberosity ; 2, To the external surface of the superior maxillary bone, above the last three molar teeth; 3, To the anterior border of the inferior maxillary bone, behind the sixth molar, in common with the maxillo- labialis, On reaching the commissure of the lips, this muscular layer appears to be continued by small tendons with the fibres of the orbicularis. The superficial plane only begins about the middle of the deep one, whose anterior half it entirely covers. Its fibres, less tendinous than those of the latter, extend from a median raphé which also divides the deep layer in its length, and are directed, some forwards, some backwards, to terminate in the following manner : the first are inserted into the external face of the super- maxillary bone, above the first molar tooth and the superior interdental space ; the second are attached to the inferior interdental space alone. Relations. —Externally, with the masseter, zygomatico-labialis, cuticularis, great supermaxillo-nasalis, supernaso-labialis, the parotid duct, which crosses it to enter the mouth, and the facial artery and veins; internally, with the buccal mucous membrane. The deep plane is accompanied and covered at its anterior border by the upper molar glands; its posterior border is margined by the inferior molar teeth, which it partially covers. The superficial layer is distinctly separated from the deep one in its anterior part, which is attached to the superior maxillary bone. Behind, these two planes adhere more intimately to one another, though they are found completely isolated by an interstice in which one or two large veins pass. Actions.—The function of the alveolo-labialis. is particularly related to mastication : this muscle, in fact, pushes between the molar teeth the portions of food which fall outside the alveolar arches ; but it cannot aid in bringing the two jaws together, as M. Lecoq has correctly observed. 3. Zygomatico-labialis. (Fig. 110, 21.) Synonyms.—Portion of the cuticularis of Bourgelat. The zygomaticus major of Man. (Zygomaticus—Percivall.) A very small, pale, and thin ribbon-like muscle, arising from the surface of the masseter, near the maxillary spine, by an aponeurosis which is con- founded with the cuticularis; it terminates on the surface of the alveolo- labialis, at a short distance from the commissure of the lips. Covered by the skin, it covers the alveolo-labialis muscle, and some of the superior molar glands, vese2ls, and nerves. This muscle pulls backwards the commissure of the lips when it is in a state of contraction. In Solipeds there is also sometimes found a muscle resembling the zygomaticus minor of Man. It is a very small fasciculus situated under the opera muscle, near its superior extremity. It appears that this fasciculus continued, above, by the fibres of the lachrymo-labialis, and is lost, below, on the alveolo-labial surface, a little beneath the carotid canal. 220 THE MUSCLES. 4. Lachrymo-labial, or Lachrymal Muscle, (Synonym.—Not mentioned by Percivall. It is the inferior palpebral muscle of Leyh.) A wide and very thin muscle, situated superficially below the eye: it is continuous, in front, with the supernaso-labialis; behind, with the oe ticularis; above, with the orbicularis of the eyelids. Its fibres, muscular and partly aponeurotic, leave the external surface of the lachievtia and zygomatic bones, are directed downwards, and become lost in a cellular fascia which covers the alveolo-labialis ; some pass beneath the zygomatico- labialis and form the zygomaticus minor, when this is present. This muscle is supposed to corrugate and twitch the skin below the eye. 5. Supernaso-labialis. (Fig. 110, 15.) Synonyms.—The maxillaris of Bourgelat. The levator labii superioris aleque nasi of Man. (Levator labii superioris aleque nasi—Percivall. Fronto-labialis—Leyh.) Situation—Direction—Form—Structure.—Situated on the side of the face, in an oblique direction downwards and backwards,' the supernaso- labialis is a wide muscle, flattened on both sides, elongated from below to above, aponeurotic at its superior extremity, and divided inferiorly into two unequal branches, between which passes the great supermaxillo-nasalis. Attachments.—-It has its origin, by its superior aponeurosis, from the frontal and nasal bones, and unites on the median line with the muscle of the opposite side. Its anterior branch, the widest and thickest, goes to the external ala of the nose and to the upper lip, where its fibres are confounded with those of the orbicularis. The posterior branch terminates at the commissure of the lips. Relations.—Outwards, with the skin; inwards, with the supermaxillo- labialis, the posterior portion of the small supermaxillo-nasalis, and vessels and nerves. Its posterior branch covers the great supermaxillo-nasalis, and the anterior is covered by that muscle. Actions.—It elevates the external ala of the nose, the upper lip, and the commissure of the lips. , 6. Supermawillo-labialis. (Fig. 110, 16.) Synonyms.—Levator labii superioris of Bowrgelat. The levator labii superioris ais oo of Man, w(Nasalis longus labii superioris—Percivall.) Situation—Direction—Form— Structure.—Lying vertically on the side of the face, below the supernaso-labialis, this muscle is a thick and conical fleshy mass, terminated inferiorly by a tendon. Attachments,—It is attached, by the upper extremity of its fleshy body, to the external surface of the supermaxillary and zygomatic bones—origin, Its terminal tendon passes over the transverse muscle of the nose, to unite with that of the opposite side, and with it to form a single aponeurotie expansion, which dips by small fibres into the subcutaneous musculo-fibrous tissue of the upper lip. Relations. —Covered by the lachrymal and supernaso-labialis muscles, this muscle in turn covers the supermaxillary bone, the bottom of the false nostril, the small supermaxillo-nasalis, and the transversalis nasi. Actions.—Ilt raises the upper lip, either directly or to one side, as it acts singly or in concert with its congener. ! It is to be remembered that we suppose the head maintained in a vertical position, 7 a : eet aC | Sa aniitio,-, i MUSCLES OF THE HEAD. 221 7. Great Supermawillo-nasalis. (Fig. 110, 19.) a ey pyramidalis-nasi of Bourgelat. The caninusof Man. (Dilatator naris lateralis—Perciva ll.) Situation— Direction— Form—Structure.—This muscle situated on the side of the face, between the two branches of the supern 4o-labialis, i in an almost vertical direction, is of a triangular form, and slight, ; tendinous at its summit. Attachments.—It has its origin, by the aponeurotic fibres of its summit, from the external face of the supermaxillary bone, below its ridge.—It terminates, by its base, on the skin covering the external wing of the nostril, a a posterior fibres being confounded with those of the orbicularis of aps. Relations. —Outwardly, with the skin and the inferior branch of the supernaso-labialis ; inwardly, with the anterior branch of that muscle, and with vessels and nerves. Actions.—It dilates the external orifice of the nasal cavity, by pulling outwards the external wing of the nostril. 8. Small Supermacillo-nasalis. (Fig. 110, 25.) Synonyms.—The nasalis brevis, and portion of the subcutaneous muscle of Bourgelat. (Nasalis brevis labii superioris— Percivall.) Girard has described, by the above name, a small, thick, and short muscular fasciculus which covers the external process of the premaxillary bone, and whose fibres, either originating from that, the supermaxillary bone, or the internal face of the supernaso-labialis muscle, terminate in the skin of the false nostril, and the appendix of the inferior turbinated bone. Rigot has attached to this muscle that described by Bourgelat as the short muscle. The latter is composed of short, transverse fibres, applied to the expansion of the cartilaginous septum of the nose which projects laterally beyond the nasal spine. These fibres abut, by their most eccentric extremities, against the skin of the false nostril and the appendix of the superior turbinated bone. In adopting Rigot’s description, it is found that the small supermaxillo- nasalis is composed of two portions, which border the re-entering angle formed by the large process of the premaxillary bone and the nasal spine. These two portions, posterior and anterior, unite at their upper extremities. The first appears to be confounded, below, with the middle anterior (depressor ale nasi), the second is continuous with the transversalis nasi. they contract, they concur in the dilatation of the false nostril and the proper nasal cavity. 9. ecicnersstle Nasi. Synonym.—( Dilatator naris anterior—Percivall. ) A single, short, and quadrilateral muscle, flattened before and behind, applied to the widened portion of the nasal cartilages, and composed of transverse fibres proceeding from one cartilage to the other. Covered by the skin and the aponeurotic expansion of the two elevator muscles of the upper lip, the transverse muscle of the nose covers the cartilages to which it is attached, and is confounded below with the orbicularis of the lips. Designed to bring together the internal ale of the nose, this muscle ought to be considered more particularly as the dilator of the nostrils. 222 THE MUSCLES. 10. The Middle (Intermediate) Anterior Muscle. Synonyms.—Medius anterior—Bourgelat. Myrtiformis of Man. (Depressor labii superiori—Percivall. Incisive muscle of the eanar lip—Leyh. A portion of the orbicularis, according to Rigot.) Bourgelat thus names a deeply-situated muscle which is fixed to the inner face of the premaxillary bone, above the incisor teeth, and whose fibres ascend to meet those of the posterior portion of the small super- maxillo-nasalis muscle, to terminate with them on the anterior appendix of the inferior turbinated bone; some fibres become lost in the lip. It is regarded as a dilator of the entrance to the nasal fossa. To study this muscle, it is necessary to raise the upper lip and remove the mucous membrane covering it. It may be dissected at the same time as the bony attachments of the superficial plane of the alveolo-labialis muscle. 11. Mawillo-labialis, (Fig. 110, 28.) Synonyms.—Depressor labii inferioris—Rigot. A dependency of the buccinator of Man. (Depressor labii inferioris—Percivall. Inferior mazillo-labialis—Leyh. Depressor anguli oris of Man.) Situation— Direction— Form—Structure.—Situated along the inferior border of the alveolo-labialis, whose direction it follows, this muscle forms a long narrow fasciculus, terminating inferiorly by an expanded tendon. Attachments.—1, By its superior extremity, to the anterior border of the lower jaw, in common with the deep plane of the alveolo labialis—fixed origin ; 2, By its terminal tendon, to the skin of the lower lip—movable insertion. Relations.—Outwardly, with the masseter and the facial portion of cuticularis of the neck; inwardly, with the maxillary bone; in front, with - the alveolo-labialis muscle, with which it is directly united in its upper two- _ thirds. Actions.—It separates the lower from the upper lip, and pulls it to the side if one alone acts. 12. Mento-labialis or Muscle of the Chin. (Fig. 110, 29.) (Synonyms.—Percivall appears to describe this and the next muscle as one. It is the quadratus menti of Man.) This name is given to a musculo-fibrous nucleus, forming the base of the rounded protuberance beneath the lower lip in front of the beard. This single nucleus is confounded, in front, with the orbicularis of the lips, and receives into its upper face the insertion of the two posterior middle muscles (levatores menti). 13. Middle (Intermediate) Posterior Muscle. _ Synonyms.—Medius posterior—Bourgelat. (Levator menti—Percivall. Incisive muscle of the lower lip— Leyh.) Bourgelat describes, by this name, a small muscular fasciculus, analogous in every respect to the medius anterior. This little muscle takes its origin from the external surface of the body of the lower jaw, beneath the inter- ’ mediate and corner incisors; from thence it descends into the texture of the lip, to unite with that of the opposite side on the upper face of the mento- labialis. Several authors have described it as a dependent of the last muscle. tnt tru ——!, MUSCLES OF THE HEAD. 223 _ It is an energetic elevator of the lower lip. To dissect this muscle, the directions given for the preparation of the anterior medius suffice. B. Masseteric or Temporo-maxillary Region. This pair region comprises five muscles for the movement of the lower jaw. These are: the masseter, temporal, internal pterygoid, external pterygoid, 1 . . ‘ ° ie meee First study the digastricus and its stylo-maxillary portion, with the in pterygoid, in preparing the hyoid muscles as they are represented in fig. 111. 2. Expose the pterygoideus externus, by removing in this preparation the hyoid bone and its ies, as well as the two preceding muscles. 3. To dissect the temporalis, excise the external | pray soa from its inferior border, an operation which exposes the orbital fasciculus of the temporalis; then turn over the piece, saw off the orbital process at each end, and remove the eye and auricular muscles. 4, Dissect the masseter in clearing away from its external surface the cuticularis and the vessels and nerves which cover it. 1. Masseter. (Fig. 110, 23.) Synonyms.—Zygomatico-maxillaris—Girard. (The zygomatico mazillaris of Leyh.) Situation—Form —Structure—Applied against the external face of the - lower jaw, the masseter is a short, wide, and very thick muscle, flattened on both sides, irregularly quadrilateral, and formed of several superposed planes, two of which are perfectly distinct towards the temporo-maxillary articula- tion, by the somewhat different direction of their fibres. These are divided by a considerable number of intersections, and are covered by a strong aponeurotic layer, which becomes gradually thinner backwards and down- wards. - Attachments. —The fasciculi of the masseter have their fixed insertion on the zygomatic crest.—Their movable insertion is on the imprints which - cover the upper half of the inferior maxillary branch. Relations.—It responds, by its superficial face, to the facial portion of euticularis colli, to the nerves of the zygomatic plexus, and several venous and arterial vessels; by its deep face, to the inferior maxillary bone, the alveolo-labialis and maxillo-labialis muscles, the superior molar glands, and two large venous branches; by its inferior border, with the parotid canal, and the glosso-facial artery and vein ; by its superior and posterior border, to the parotid gland. Its deep plane responds, anteriorly, with the temporo- maxillary articulation, and is so intimately confounded with the temporalis, that it is impossible to define the respective limits of the two muscles. Action.—This muscle, the special elevator of the lower jaw, plays an important part in mastication. It always acts as a lever of the third class, the middle line, which represents the resultant of all its constituent fibres, passing behind the last molar. 2. Temporal or Crotaphitic Muscle. Synonyms.—Temporo-maxillaris—Girard. (The temporo-mavillaris of Leyh.) Situation— Form—Structure.—Situated in the temporal fossa, to which it is moulded, and which it fills, this muscle is flattened from above to below, divided by strong tendinous intersections, and covered by a nacrous aponeurotic layer. Attachments.—It takes its origin: 1, In the temporal fossa and on the Cr i ell OD ae Oe ee” eee eee i, ti eh — ae 224 THE MUSCLES. bony crests which margin it; 2, By a wide fasciculus, paler than the other rtion of the muscle, but not unconnected with it, from the imprints situated behind the crest surmounting the orbital hiatus. It terminates on the coronoid process and the anterior border of the branch of the lower jay. . : Relations.—This musele covers the temporal fossa, and is covered by the temporo-auricularis muscles, scutiform cartilage, internal scuto-auricularis, the fatty cushion at the base of the ear, and by another adipose mass which separates it from the ocular sheath. Its deep -fasciculus responds, by its internal face, to the two pterygoid muscles. Action.—It brings the lower jaw in contact with the upper, by acting as a lever of the first kind; but the orbital portion of the muscle elevates the inferior maxilla and moves it laterally by a lever of the third class. 3. Internal Pterygoid. Synonyms.—Portion of the spheno-maxillaris of Bourgelat. (The pterygoideus internus. of Percivall. Leyh designates the plerygoideus internus and externus as one muscle, the epheno-mazxillaris or internal masseter.) Situation—Form —Structure.—Situated in the intermaxillary space, opposite the masseter, the pterygoideus internus, although not so strong as that muscle, yet so closely resembles it in form and structure as to be named by Winslow the internal masseter. | Attachments.—1. To the palatine crest and subsphenoidal process—fiwed insertion: 2. In the hollow excavated on the inner face of the branch of the lower jaw—movable insertion. Relations—Outwardly, with the pterygoideus-externus, the orbital fasciculus of the temporal, the maxillo-dental nerves, mylo-hyoideal, and lingual muscles, arteries and veins, and the inner surface of the bone which receives its movable insertion. Inwardly, with the tensors palati—external and internal, the guttural pouch, the hyoideus magnus, hyoid bone, digastricus, the hypoglossal and glosso-pharyngeal nerves, glosso-facial artery and vein, the hyoglossus longus and brevis muscles, the laryngo-pharyngeal apparatus, the Stenonian duct, and the submaxillary glands. Action.—It is an elevator of the lower jaw, and also gives it a very marked lateral or deductive motion. If the left muscle acts, this movement carries the inferior extremity of the lower jaw to the right; and if it be the right muscle, then in the contrary direction. 4, External Pterygoid. Synonym.—Portion of the spheno-maxillaris of Bourgelat. Form—Situation—Structure—Attachments—A small, short, and very thick muscle, situated within and in front of the temporo-maxillary articulation, formed of slightly tendinous fasciculi which leave the inferior face of the sphenoid bone and the subsphenoidal process, and are directed backwards and upwards to be fixed to the neck of the inferior maxillary condyle. Belalions —Oakweadly, with the orbital fasciculus of the temporal muscle, and the temporo-maxillary articulation. Inwardly, with the numerous nerves emanating from the inferior maxillary branch, and with the internal pterygoid and tensors palati. Action.—When the two external pterygoids act in concert, the inferior maxilla is pulled forward; but if only one contract, the propulsion is MUSCLES OF THE HEAD, - 225 Seg by a lateral movement, during which the extremity of the jaw _ is carried to the opposite side. 2 5. Digastricus. Synonyms.—Bourgelat has made two distinct muscles of this—the digastricus een Girard has described it as the shy linanacilinbtat CPorctvall ra ‘followed Bourgelat’s example, and divided the muscle into digastricus and _ stylo-mazxillaris. Leyh adopts thé same course.) Form—Structure—Situation—Direction.—Composed of two fleshy bodies more or less divided by intersections, and united at their extremities by a median tendon, this muscle is situated in the intermaxillary space, and extends from the occiput to near the symphysis of the chin, describing a - eurve upwards. _ _ Attachments.—It takes its origin from the styloid process of the occipital bone, by its superior fleshy body. It terminates: 1, On the curved portion of the posterior border of the lower jaw by a considerable fasciculus, which is detached from the superior fleshy body ;1 2, On the internal face of the same bone and the straight portion of its posterior border, by aponeurotic digitations which the muscular fibres of the inferior fleshy body. Relations.—The superior belly of the muscle responds, superficially, to the aay gland and the tendon of insertion of the sterno-maxillaris ; iw y, to the guttural pouch, the submaxillary gland, and the larynx and _ pharynx. The median tendon passes through the ring of the hyoideus _ magnus. The lower belly is in contact, outwards, with the ramus of the ‘inferior maxilla; inwards, with the mylo-hyoideus muscle. ____ Action.—When this muscle contracts, it acts at the same time on the 4 pes bone, which it raises in becoming straight, and on the lower jaw, < » \ % ; , it pulls backwards and depresses‘at the same time. C. Hyoideal Region. ____ This region includes six muscles grouped around the os hyoides, which _ they move. Five of these are pairs: the mylo-hyoideus, genio-hyoideus, stylo- __ hyoideus, kerato-hyoideus, and the occipito-styloideus. The single one is the _ transversalis hyoidei. Preparation.—Separate the head from the trunk, and remove the muscles of the cheeks on one side, with the parotid gland. 2. The branch of the inferior maxilla being thus exposed, it is sawn through in two places; at first behind the last molar, then in front of the first. 3. After having separated the pterygoids and the siylo-maxillaris from the upper fragment or condyle, and the coronoid process, it is torn off by pulling ‘it adweetis; thon the pterygoids and the digastricus are excised. 4. The inferior fragment of the jaw bearing the molar teeth is turned down by isolating the mylo-hyoideus from the mucous membrane. 5. Carefully remove the tongue by separating its extrinsic muscles the genio-hyoidleus, the anterior appendix of the hyoid bone, the transverse muscle, and the small hyoideus. _ ‘The dissection having been performed in this manner, the large hyoideal branch may be ) . ted from the small, by sawing through the head ay or? inally, leaving the si menti intact, and turning down the corresponding half to the side already as well as the great hyoid branch, the pharynx, larynx, and soft palate. 1. Mylo-hyoideus. ; Form—Situation—Structure.—A membranous muscle situated in the _ intermaxillary space, flattened from side to side, elongated in the direction —. -_-—s« * ‘This is the fasciculus which Bourgelat has described as a distinct musele, and named the stylo-~mazillaris, Q 226 THE MUSCLES. of the head, thinner and narrower below than above, and formed entirely of fleshy fibres which extend transversely from its anterior to its posterior border. Inferiorly, it is composed of a small fasciculus, which is distinguished from the principal portion by the slightly different direction of its fibres, and which covers in part the external surface of the muscle, Fig. 111. HYOIDEAL AND PHARYNGEAL REGIONS. 1, Neck of inferior maxilla; 2, Hard palate; 3, Molar teeth ; 4, Buccal membrane ; 5, Submaxillary glands; 6, Soft palate; 7, Tendon of hyoideus magnus through which the tendon, 8, of the digastricus passes; 9, Lower portion of digastricus; 10, Stylo-hyoideus; 11, Buccal nerve; 12, Zygomatic arch; 13, Orbital branch of fifth pair of nerves; 14, Articular process of temporal bone; 15, Right cornu of hyoid bone; 16, Hyo-glossus longus, or Kerato-glossus; 17, Lingual nerve; 18, 18, Tongue; 19, Angle of left branch of inferior maxilla; 20, Submaxillary gland, left side; 21, Subscapulo-hyoideus; 22, Great hypoglossal nerve; 23, Hyo- thyroideus; 24, Sterno-hyoideus; 25, Sterno-thyroideus; 26, Subscapulo hyoi- deus; 27, Thyroid gland; 28, External carotid artery ; 29, Pneumogastric nerve ; 30, Stylo-hyoideus ; 31, Genio-hyoideus, Attachments.—It originates from the mylo-hyoid line by the anterior extremities of its fibres. lts movable insertion takes place on the inferior face of the hyoid body, on its anterior appendix, and on a fibrous raphé which extends from the free extremity of this appendix to near the genial surface, and which unites, on the median line, the two mylo-hyoidean muscles. Relations.—By its external face, with the inferior maxilla, the digastric muscle, and the submaxillary lymphatic glands. By its internal face, with the sublingual gland, the Whartonian duct, the hypoglossal and li nerves, the genio-glossus, hyo-glossus longus and brevis, and genio-hyoideus. Its superior border responds to the internal pterygoid. Action.—In uniting on the median line with that of the opposite side, this muscle forms a kind of wide band or brace on which the tongue rests. When it contracts, it elevates this organ, or rather applies it against the palate. 2. Genio-hyoideus. Form—Structure—Situation.—A fleshy, elongated, and fusiform body, tendinous at its extremities, but éspecially at the inferior one, and applied, with its fellow of the opposite side, to the mylo-hyoidean brace. r : MUSCLES OF THE HEAD. 227 Aitachments.—By its inferior extremity it is fixed to the genial surface— rigin ; by its superior, it reaches the free extremity of the anterior appendix f the ‘hyoid body—termination. ____ Relations. —Outwards and downwards, with the mylo-hyoideus ; inwards, with its fellow, which is parallel to it; above, with the genio-glossus. Action —It draws the hyoid bone towards the anterior and inferior part _ of the intermaxillary space. 3. Stylo-hyoideus. (Synonyms.—The hyoideus magnus of Percivall, The kerato-hyoideus magnus of Leyh.) : Form — Structure — Situation — Direction.— Thin and fusiform, this muscle, smaller than the preceding, and, like it, tendinous at both its _ extremities, is situated on the side of the laryngo-pharyngeal apparatus and the guttural pouch, behind the large branch of the hyoid bone, whose direction it follows. Attachments.—Above, to the superior and posterior angle of the styloid bone—jixed insertion; below, to the base of the cornu of the os hyoides —wmovable insertion. Relations—Outwards, with the pterygoideus internus; inwards, with _ the guttural pouch, the pharynx, and hypoglossal nerve. Its anterior border is separated from the posterior border of the styloid bone by the a alge artery and glosso-pharyngeal nerve; along the posterior lies the upper belly of the digastricus. Its inferior tendon is _ perforated by a ring for the passage of the cord intermediate to the two _ portions of the latter muscle. Action.—It is antagonistic to the preceding muscle, drawing the body of the paeae bone backwards and upwards. 4. Kerato-hyoideus. — is the hyoideus parvus of Percivall, and the small kerato-hyoideus of : A very small fasciculus, triangular in shape, and flattened on both sides. Inserted, on one side, into the posterior border of the styloid cornu and the _ inferior extremity of the styloid bone; and on the other, to the superior _ border of the thyroid cornu. It responds, outwardly, to the basio-gloss and the lingual artery ; inwardly, to the buccal mucous membrane. ____ It approximates the cornua of the os hyoides to each other. : 5. Occipito-styloideus. __ Synonyms.—T iis is the muscle which, up to the present time, has been described by veterinary anatomists as the stylo-hyoideus. This name has been’given to the muscle mpi Girard the kerato-hyoideus magnus. A small, flat, and triangular muscle like the preceding, yet thicker and mor filling the space comprised between the styloid process of the occipital and the horizontal portion of the posterior border of the styloid bone. Its fasciculi become longer as they are situated posteriorly, are tendinous, and are carried from one of these bones to the ae C ily, it responds to the parotid gland; inwardly, to the guttural _ pouch, which it covers for its whole extent; its posterior border is largely f ‘confounded with the superior insertion of the digastricus. When this _ tmiuscle acts, it causes the os hyoides to swing, carrying its inferior extremity | Backwards and downwards. Q@2 228 THE MUSCLES. 6. Transversalis Hyoidei: . By this name Bourgelat has described a short riband of parallel muscular fibres, which unites the superior extremities of the styloid cornua, and approximates them to each other. DIFFERENTIAL CHARACTERS OF THE MUSCLES OF THE HEAD IN OTHER THAN SOLIPED ANIMALS, A. Facial Iegion. Remrnants.—There are found in the Oz: 1. An orbicular muscle of the lips, analogous to that in the Horse. 2. An alveolo-labialis of the same kind (fig. 112, 5). : 3. A zyqgomaticus or zygomatico-labialis, stronger and redder than in Solipeds. Its aponeurosis of origin, covered by the cuticularis muscle of the face, extends upon the surface of the masseter muscle as far back as the zygomatic arch, to which it is attached (fig. 112, 7). Fig. 112. SUPERFICIAL MUSCLES OF THE OX’S HEAD. 1, Supermaxillo-labialis; 1, 1’, Accessory fasciculi of the supermaxillo-labialis; 2, Supermaxillo-nasalis magnus; 3, Supernaso-labialis; 4 Lachrymalis; 5, Alveolo-labialis; 6, Maxillo-labialis confounded with the preceding; 7, Zy matico-labialis; 8, Frontal, or cuticularis muscle of the forehead; 9, Orbicular muscle of the eyelids; 10, Zygomatico-auricularis ; 11, External temporo-auricu- laris; 12, Scutiform cartilage; 13, External scuto-auricularis; 14, Mastoid pues 15, Masseter; 16, Stylo-hyoideus; 17, Digastricus; 18, Sterno-maxil- ary fasciculus belonging to the cuticularis muscle of the neck; 19, Trachelo- hyoideus. (subscapulo-hyoideus); 20, Sterno-suboccipitalis (sterno-maxillaris, or mastoideus); 21, Anterior branch of the superficial portion of the mastoido- humeralis (levator humeri); 22, Superior branch of ditto; 23, Deep portion of same muscle; 24, Trachelo-atloideus, peculiar, to Ruminants and Pachyderms; 25, Great anterior straight muscle of the head, : 7 - MUSCLES OF THE HEAD. 229 _ 4. A lachrymalis, thicker and more developed than in the Horse, Its most anterior th the zygomaticus, and are lost on the alyeolo-labialis surface; the posterior pass over the aponeurotic tendon of the zygomatico-labialis, and are _ onfounded with those of the cuticularis. Above, it joins the orbicularis of elids in a still more intimate manner than in the Horse; so that it is almost impossible to _ distinguish the limits of the two muscles (fig. 112, 4). ___ -. A supernaso-labialis continued, above, with the inferior border of the frontal or _ fronto-cuticularis muscle; and divided, inferiorly, into two branches, which comprise between them the supermaxillo-labialis and the pyramidalis-nasalis. These two . however, are not dis as in Solipeds, the anterior covering the preceding muscles, and the posterior, of but little importance, passing beneath them to lose itself > my a of ay fe Be (fig. 112, {4 oe i ialis, which gains the middle of the muzzle by passing alo thie inner sido of the nostrils (fig. 112. 1). ‘ Sra = 7. Two additional supermazillo-labialis muscles, considered as accessories to the first, and which originate with it. Each terminates by a ramifying tendon that passes under the nostril to mix in the tissue of the upper lip (fig. 112, 1',1’). 8. A pyramidalis or great supermazillo-nasalis, situated between the supermaxillo- labialis and its two accessory muscles, and deriving its origin, in common with these three muscles, in front of the maxillary spine (fig. 112, 2). 9. A mazillo-labialis, confounded with the alveolo-labialis, and having no terminal The 10. A mento-labialis, attached to the body of the inferior maxillary bone, as in the Horse, by two middle posterior muscles. No anterior middle muscle has been found by us; and it is certain that there is no naso-transversalis or small supermazillo-nasalis ~present. : In the Sheep, the supernaso-labialis does not exist; apart from this uliari there is no difference between the facial muscles of this saiuat and the Ox. ai __ Pig.—This animal has neither the lachrymalis, supernaso-labialis, or naso-transver- _ salis muscles. The small supermazillo-nasalis is present ; it is short, very thick, and situated near the margin of the nostrils. The supermasillo-labialis and the great | are replaced by three prey ee nearly parallel, lying on the side of the face. The superior originates in the rymal fossa, and terminates by a _ tendon in the middle of the snout. The inferior, with the middle, leaves the imprints _ in front of the zygomatic ridge, and is continued at its inferior extremity by a tendon divided into several niyo p= pass — the pserngies gt united to the tendon of _ the superior ion: this is done in such a manner that the external opening of the nose is cD gag the inner side by a kind of fibrous cravat which, ‘when these two muscles contract, carries this opening outwards. It will also be understood that the superior fleshy iy, acting alone, ought to elevate the snout, while the inferior i is the rep it in draw: 7 it to one side. With regard to the intermediate fleshy mass, it a tative o the pyramidalis of the Ox, and terminates in a great quantit linous fibrille at the internal ala of the nose. sare y of Carntvora.—In the Dog and Cat the following peculiarities are found :— The labialis (or orbicularis) is quite rudimentary. The buccinator is very thin and formed of ne one muscular plane. _ The zygomatico-labialis is continued, superior, y, with the zygomato-auricuralis, The supernaso-labialis represents a wide, undivided, muscular ex ion, united riorly to the cuticularis of the forehead, and terminating inferioe!y on the upper The supermazillo-labialis and the supermazillo-nasalis magnus constitute a sing] leshy body formed of several parallel fasciculi, which take their origin above the eo _ orbital foramen, and termina te together at the external wing of the nose and in the There is no supermazillo-nasalis parvus, or naso-transversalis. _ The middle anterior (d alz nasi) is perfectly developed, | _‘The mento-labialis and its suspensory muscle, the middle posterior, are scarcely pare , B. Masseteric or Temporo-maxillary Region, In Ruminants, the masseter and temporal are not so large as in Solipeds. In the Jarniv however, they offer a remarkable development. The origin of the ptery- ideus internus in Ruminants is nearer the mitidle line than in the Horse. Its obliquily also greater, and the movements of diduction it gives the lower jaw are more 230 _ YH. MUSCLES. : extensive. In all the animals, the sfylo-~mazillaris fasciculus of the digastricus is entirely absent, and the muscle has only a single belly extending directly from the — occipital to the maxil'ary bone. In the Ox is found a small square muscle, formed of transverse fibres, which unites the two digastric muscles by ing beneath the base of the tongue. This muscle, in contracting, may raise the hyoideal apparatus, and in this —_ VS ger eos the tendon of the digastricus and the inferior ring of the stylo- yoideus. C. Hyoid Region. The two fleshy planes composing the mylo-hyoideus are more distinct in Ruminants Pam: than in the Horse. The stylo-hyoideus of these animals eommences by along thin : tendon. The muscle has no ring for the passage of the digastricus, a feature observed in all the domesticated animals except Solipeds. In the Carnivora, the stylo-hyoideus, formed by a narrow, very thin, and e fleshy band, commences on the mastoid portion of the temporal bone by a small tendon; the kerato-hyoideus is remarkable for its relatively considerable volume ; the occipito- styloideus and the transversalis hyotdeus are absent, COMPARISON OF THE MUSCLES OF THE HUMAN HEAD WITH THOSE OF THE DOMESTICATED ANIMALS, In Man, there are described as muscles of the head, the epicranial muscles, muscles of - : the face, and those of the lower jaw. The hyoid and digastric muscles are reckoned in the region of the neck. Here they will be placed in the region of the head. . A. Epicranial Muscles. . The middle portion of the human cranium is covered by an apoueurosis that adheres closely to the hairy scalp, but glides easily on the surface of the bones, ‘To the cireum- ference of this be pee trme aponeurosis are attached four muscles which move it. One of them, attached behind to the superior occipital curved line, is named the occipital muscle ; another, fixed in front of the forehead, is called the frontal muscle ; the other two, double and lateral, are inserted on the face of the temporal bone or the external ear, and are designated auricular muscles. These epicranial muscles move the scalp for- wards, backwards, and sideways. f B. Muscles of the Face. These are fourteen in number, ten of which are found in the domesticated animals, We commence by describing these common muscles (fig. 113). 1. The orbicularis of the lips, which has a fasciculus that passes to the skin from the columna of the nose; this fasciculus is termed the depressor of the columna, or moustache muscle (naso labialis). : 2. The buccinator, corresponding to the alveolo-labialis of animals. Besides its office in mastication, it takes an important part in the blowing of wind instruments, : 3. The superficial elevator of the wing of the nose and the wpper lip. Tt resembles the supernaso-labialis, descends from the orbital margin of the supermaxilla, passes along the wing of the nose, and is lost in the upper lip. 4. The deep elevator of the wing of the nose and the upper lip, whose analogue is found in the supermaxillo-labialis of animals. sel 5. The great zygomaticus, whose presence is constant in all species. 6. The small zygomaticus, represented in the Horse by only the small oblique fasciculus sometimes found beneath the great zygomaticus. The small zygomaticus and the two elevators of the lips are ea muscles; by their simultaneous contraction they express discontent and melancholy. The great zygomaticus, on the contrary, is the muscle of laughter; it draws the commissures of cae the lips outwards. - a 7. The canine, or great supermaxillo-nasal of animals, is attached beneath the infra- _ orbital foramen, and terminates in the skin of the upper lip. 8. The risorius of Santorini. 9. The muscle of the chin (mento-labialis). 10. ‘Lhe myrtiformis, or middle anterior of Bourgelat. : The otber facial muscles of Man, whose analogues it is difficult or impossible to find __ in animals, are :— ; | m MUSCLES OF TUE TRUNK. 231 It. The triangularis of the lips, which is inserted into the anterior face of the or maxilla, and is carried upwards to the Fig. 113. nissure of the lips. By its contraction it ss the face an expression of melancholy or 12. The — menti, which, after being _ attached to the maxilla within the mental fora- oop) Scag upwards on the skin of the lower lip, w it depresses, and thus contributes to th of fear or dismay. 18. The transversalis nasi (compressor nas’), _ a muscle which is fixed into the supermaxilla _ and on the bridge of the nose, where it is con- foun with the opposite muscle. ‘4. The dilator of the ala of the nostril, a _ very small triangulur fasciculus applied to the external part of the nostril, which, by contract- ing, it elevates. C. Muscles of the Lower Jaw. There is nothing remarkable to be noted in the masseler, temporal, or pterygoid muscles. The Bees belly of the digastricns is not at- _ tached y to the inferior maxilla. D. Hyoid Muscles. , 2 MUSCLES HE HUMAN HEAD; _ These are only three in number :— rig Seton er ly ; 1. The ideus 2 The stylo-hyoideus, which commences at 1, Frontal portion of the occipito-fronta- _ the styloid process of the temporal bone, and lis; 2, Its occipital portion; 3, Its os + a ring for the tendon of the digastyicws: page K 4, ochesien renin’ 3.' i ideus. rum ; yramidalis nasi ; ‘om- __ Wedo not find in Man the occipito-styloideus, pressor nasi; 7, Orbicularis oris; 8, _kerato-hyoideus, or the transv is-hyoideus. Levator labii superioris aleque nasi; -— 9, Levator labii superioris proprius ; “ Axillary Region. 10, Zygomaticus minor; 11, Zygo- 79 . - + iad y maticus major; 12, Depressor labii : This Sac ge two muscles, pairs, _inferioris; 13, Depressor anguli oris; F placed the sternum, in the arm- 14, Levator labii inferioris ; 15, Super- r Diag terminate on the anterior limb, ce se py-rrancict, 16, Its ovr are the superficial and deep pec- reg oe eens eae soe : Buccinator; 19, Attollens aurem; 20 torals,* Temporal fascia covering temporal ; Seen nae muscle; 21, Retrahens aurem; 22, - : 2. Har ace ay a Aa Anterior belly of the di; tricus, with and allow it to hang, so as to separate it from t¢mdon passing throug’ Pulley 3 23, the opposite one, 3. Remove the skin ‘with Stylo-hyoid muscle; 24, Mylo-hyoi- and dissect, on the side corresponding to 4¢483 25, Upper part of sterno-mas- ‘tached limb, the two muscles which form toid; 26, Upper part of trapezius— : pectoral. 4. Prepare the deep the muscle between 25 and 26 is the ral on the sp side. To do this, splenias. ' temove the panniculus cautiously, so. #8 not to injure the muscle about to be examined ; _ divide the superficial pectoral transversely, and turn back the cut portions to the right and left; divide also the mastoido-lumeralis (levator humeri) and cervical trapezius near thei insertion into the limb, and reflect them upon the neck. 1. Superficial Pectoral. (Fig. 114, 9, 10.) 8.—Muscle common to the arm and fore-arm—Bourgelat. Pectoralis magnus of ( Pectoralis transversus—Percivall, Leyh divides this muscle into two portions, which he designates the sterno-radialis and smail sterno humeralis). i el a * , = & justification of the employment of these new denominations, see the note at p. 177. ’ ae. 4 ; : . ._ oF ee oe ok ee =, — ee ee —————— ee ee 232 THE MUSCLES. SS a E i Hil ulti MUSCLES OF THE AXILLARY AND CERVICAL REGIONS. 1, Portion of the cuticularis colli; 2, An- terior portion of the mastoido-hume- ralis; 3, Posterior portion of ditto; 4, Sterno-maxillaris; 5,Subscapulo-hyoi- deus; 6, Sterno-hyoideus; 7, Sterno- _ thyroideus; 8, Scalenus; 9, Sterno- humeralis; 10, Sterno-aponeuroticus ; 11, Sterno-trochineus (pectoralis mag- nus); 12, Portion of the fascia en- veloping the coraco-radialis, receiving part of the fibres of the sterno-trochi- neus; 13, Sterno-prescapularis; 14, Its terminal aponeurosis, Situation —Composition.—This muscle is situated between the two anterior limbs, occupies the inferior surface of the chest, and is formed by two tions which adhere closely to each other; but are yet perfectly distinct. Following the example of Girard, we will deseribe these as two particular muscles by the names of sterno-humeralis, and sterno- aponeuroticus. A. Sreryno-numerauis. — Form — Structure.—This is a short, bulky muscle, flattened above and below, contracted at — its termination, and composed almost — entirely of thick parallel fibres. Direction and Attachments.—It com- mences on the anterior appendage and the inferior border of the sternum, and is directed obliquely backwards, downwards, and inwards, to reach the anterior ridge of the humerus, where it terminates by an aponeurosis common to it, the mas- toido humeralis, and the sterno-aponeuro- ticus. Relations.—It responds, by its ex- ternal face, to the skin, from which it is separated by a cellular layer, and to the inferior extremity of the cuticularis colli; by its internal face, to the sterno- aponeuroticus and sterno-prescapularis. Its anterior border forms, with the mas- toido-humeralis, a triangular space ocen- pied by the subcutaneous, or “ plate,” vein of the arm. Action.—It acts principally as an adductor of the anterior limb. B. Srerno-arongvroricus.—Form— Structure — Direction — Attachments. —A very wide, thin, and pale quadrilateral muscle formed of parallel fleshy fibres, which arise from the entire inferior border of the sternum, to pass at first outwards, then downwards, and terminate in the following manner: the anterior fibres go to the aponeurosis which attaches _ the mastoido-humeralis and sterno-hu- meralis to the anterior ridge of the humerus; the posterior fibres are also continued by a very thin fascia, which is spread inside the limb to the external face of the antibrachial aponeurosis. Relations—By its superficial face, MUSCLES OF THE TRUNK. 233 with the skin, which adheres intimately to it by means of a dense cellular and with the sterno-humeralis, which covers its anterior border. 3 its deep face, with the two portions of the deep pectoral, the coraco- radialis (flexor brachii), and the long extensor of the fore-arm; it A also responds, by this ace, to the antibrachial aponeurosis and the sub- | cremoeidl vein of the fore-arm, which it maintains applied against that Action.—It is an adductor of the anterior limb, and a tensor of the _ antibrachial aponeurosis. 2. Deep Pectoral. (Figs. 114, 11, 13; 115, 1.) Synonym.—The pectoralis parvus of Man. _--Volume—Situation—Composition—An enormous muscle, situated be- _ neath the thorax, and composed, like the preceding, of two perfectly distinct _ portions, described by Girard as two muscles, and designated by him as the _ sterno-trochineus and sterno-prescapularis. A. Srerno-rrocuiyevs.—Pectoralis magnus of (Percivall, Rigot, and) Bo t. (The great sterno-humeralis of Leyh.) 7 olume—Ezxtent.—This muscle, the largest of the two, offers a con- siderable volume. Extending from the ninth or tenth rib to the upper of the arm, it at first lies beneath and against the abdomen, then _ beneath the chest, and at last is comprised between the walls of the latter cavity, and the internal face of the anterior limb. Form.—lIt is thin and flat above and below in its posterior third, thicker and depressed from side to side in its middle third, and narrow and pris- matic in its anterior third. Its general form may be ‘compared to that of a somewhat irregular triangle, elongated from before to behind, which would oes ty short posterior border, a longer internal or inferior border, and ; or superior still more extensive. __ Structwre.—It is entirely composed of thick, parallel, fleshy fasciculi, all of which leave the posterior or internal border of the muscle to gain its ‘narrow or anterior extremity. These fasciculi, as they approach the superior _ border, become longer, and those which proceed ‘from the posterior border com- _tmence by aponeurotic fibres. Unfrequent intersections of fibrons tissue exist towards the anterior extremity of the muscle. Aitachments.—It originates: 1, From the tunica abdominalis by the apo- irotic fasciculi of its postcrior border ; 2, By its internal border, from the posterior two-thirds of the inferior border of the sternum. It terminates, by its anterior extremity, on the internal tubercle at the head of the humerus, the tendon of origin of the coraco-humeralis, and the fascia enveloping the co-radialis. Through the medium of this fascia, it is inserted into the ternal lip of the bicipital groove formed by the great trochanter, and is _ “try two terminal — of the supraspinatus muscles. (See , Big 1 2 -. tists deep face, which" is successively superior and internal, vovers the external oblique and the straight muscle of the abdomen, the 18 magnus, costo-sternalis, and sterno-prescapularis, as well as some _thoraco-muscular nerves ; all these relations are maintained by means of a oose and abundant cellular tissue. Its superior face, which alternately ‘8 downwards and outwards, responds: to the skin, from which it is eparated by a slight cellulo-fibrous fascia; to the sterno-aponeuroticus ; and to the muscles, vessels, and nerves of the inner aspect of the arm, through he 234 THE MUSCLES. the medium of the subbrachial aponeurosis of the panniculus and a con- siderable quantity of cellular tissue. Its upper border adheres in an intimate manner to the last-named muscle, and is bordered by the spur (external thoracic) vein. The large vascular trunks which leave the chest to reach J ‘ : ee), Pe ee ee MUSCLES, AXILLARY AND THORACIC : 1, Deep pectoral, or pectoralis major, with 2, The pectoralis parvus; 3, Superficial pectoral, or pectoralis trans- or mastoido-humeralis; 9, 10, Outer attachments of the deep pectoral muscle; 11, Sterno-thyroideus; 12, Sterno-hyoideus; 13, Inferior scalenus; 14, Superior scalenus; 15, Rhomboideus; 17, Point of sternum; Lateralis sterni, or transversalis of the ribs; 6, Sterno-maxillaris; 7, 16, Panniculus; 8, 19, Levator humeri, 18, Intercostal muscle ; 18’, Abdomen; 20, Subscapularis; 21, Ulna, versus, including the sterno-aponeuroticus and sterno-humeralis; 4, Their attachment to the sternum; 5, the anterior limb, pass above its anterior extremity, by crossing its direction. Action.—It pulls the whole limb backwards, in pressing on the angle of the shoulder. ' B. Srerno-prescapunaris.—(The pectoralis parvus of Percivall and Bourgelat. )}—Form—Siluation—Direction.—A long prismatic muscle, con- J MUSCLES OF THE TRUNK. 235 tracted at its two extremities, situated in front of the preceding, arising from the sternum, directed forwards and outwards towards the scapulo- humeral le and afterwards reflected upwards and backwards on the _ anterior border of the shoulder, which it follows to near the cervical angle of the scapula. } Structure and Attachments.—It is formed of very large fleshy fasciculi, analogous to those of the sterno-trochineus, which originate, by their inferior extremities, from the sides of the sternal keel and the cartilages of the first three or four ribs. They follow the direction of the muscle, and terminate, one above the other, on a short aponeurosis which covers the Supraspinatus, and is confounded with the external aponeurosis of the seapula (Fig. 114, 14). Relations.—In its axillary portion, this muscle responds, inwardly, to the costo-sternalis, the first sternal cartilages, and the corresponding inter- costal muscles: outwards, to the sterno-trochineus and sterno-aponeuroticus. Tn its prescapular portion, it is in relation, outwardly, with the mastoido- humeralis and trapezius; inwardly, with the subscapulo-hyoideus, the scealenus, and the angularis of the scapula; behind, with the supraspinatus _ which is separated from it by the external scapular aponeurosis. . Action.—This muscle is a congener of the sterno-trochineus, and pulls the seapula backwards and downwards. It is also a tensor of the scapular aponeurosis. te DIFFERENTIAL CHARACTERS OF THE MUSCLES OF THE AXILLARY REGION IN OTHER THAN SOLIPED ANIMALS. With regard to the superficial pectoral, it is remarked that in the Oz, Sheep, and aif the sterno-lumeralis is small and less distinct from the sterno aponeuroticus than in ipeds ; and that in the Dog and Cat, the sternc-aponeuroticus is very thin avd narrow. In the deep pectoral there is found, in the Oz, a sterno-prescapularis scarcely distinct ___ from the sterno-trochineus, and which does not extend beyond the inferior extremity of the supraspinatus. In the Sheep, this muscle is quite confounded with the sterno- _ trochineus. In the Pig, the sterno-prescapularis somewhat resembles that of the Horse. - Its inferior extremity only covers the first chondro-sternal articulation; the superior extremity is more voluminous. With regard to the sterno-trochineus, it terminates on the summit of the great trochanter, after detaching a short branch tv the tendon of the coraco-humeralis. The sterno-prescapularis of the Dog is very feeble, and terminates with the principal muscle on the lumerus. le cs Sie In each costal region we find fifty-four muscles, which concur, more or less directly, in the respiratory movements. These muscles are: 1, The _ great serratus ; 2, The costo-transversalis ; 3, Seventeen external intercostals ; 4, Seventeen internal intercostals; 5, Seventeen supercostals; 6, The triangularis sterni. as Preparation—1. Place the subject in the second position. 2. Remove the fore- limb and all the muscles attaching it to the trunk, by sawing through the scapula as shown in figure 10£, in order to expose the great serratus and costo-transversalis muscles ; finish the dissection of the former by taking away all the yellow fibrous tissue which covers its posterior dentations. 3. Study the external intercostals and the supercostals, after removing the great oblique muscle of the abdomen, the serrati muscles, the ‘common intercostal (ilio-costalis), and tie ilio-spinalis. 4. Excise some external inter- costals in order to show the corresponding internal ones, 5. The triangularis is dis- sected on another portion, which is obtained in separating the steruum from the thorax by sawing through the sternal ribs a little above their inferior extremity. = ~ 4 i ; COSTAL REGION. ‘ & y — ere“ ha a ——_ >” le ee 236 THE MUSCLES. 1, Great Serratus. (Fig. 105, 15.) Synonyms,—Costo-subscapularis— Girard, Posterior portion of the serratus magnus of Bourgelat. (A portion of Percivall’s serratus magnus.) Form—Situation.—A very wide muscle, disposed like a fan, split into digitations at its inferior border, applied against the thoracic Bis aa partly concealed by the shoulder. : Structure.—It is composed of divergent fleshy fibres, all of which con- verge towards the superior extremity of the scapula, and are covered by a very strong aponeurosis that gradually diminishes from above to below, _ and only adheres to the muscle in its inferior part. Attachments.—1, To the external face of the eight sternal ribs; 2, To the anterior triangular surface of the internal face of the scapula, behind the angularis, with which it is confounded; 3, To the whole extent of the posterior triangular surface of that bone. ) On reaching the scapula, the aponeurosis separates from the fleshy fibres, and is inserted alone into the fibrous plane which covers the muscular fasciculi of the subscapularis. / Relations.—The great serratus responds: outwardly, and through the medium of an abundant supply of cellular tissue, which facilitates the play of the limb against the lateral wall of the thorax, to the subscapularis, supraspinatus, the adductor of the arm, great dorsal (latissimus dorsi), and the mass of olecranian muscles; inwardly, to the first seven external inter- costals, to the sides of the sternum, and the anterior small serratus. Its four posterior digitations cross the first five of the great oblique muscle of the abdomen, and are covered by a prolongation of the abdominal tunic. Action.—With that of the opposite side, this muscle constitutes a vast brace or girth on which the thorax rests when the animal is supported on its limbs; it therefore acts, in relation to the trunk, like a suspensory ligament. When it contracts, its fixed point being the thoracic walls, it pulls the superior extremity of the scapula downward and backward, and causes this portion of the limb to perform a swinging movement which carries the inferior angle upwards and forwards. If the limb is the fixed point, then it raises the thorax between the two anterior members, and assists in the respiratory movements by elevating the ribs. 2. Transverse Muscle of the Ribs. (Fig. 105, 16.) Synonyms.— Costo-sternalis—Girard. .(Lateralis sterni—Percivall.) Form — Structure — Direction — Situation.— This is a flattencd band, aponeurotic at its extremities, oblique from upwards and forwards, and situated under the preceding muscle, at the inner aspect of the deep pectoral. Attachments.—Its posterior extremity is fixed to the sternum and the fourth sternal cartilage; the anterior to the external face of the first rib. Relations.—Inwardly, with the second and third ribs, into which are often inserted some of its fasciculi, and with the three first intercostal muscles. Outwardly, with the two portions of the deep pectoral muscle. Action—This is an auxiliary to the expiratory muscles. (Leyh says its action is to raise the ribs and their cartilages, and thus to enlarge the anterior portion of the thorax during inspiration.) PS. — i J * «x ate ere, ‘ ‘ THE MUSCLES. 237 3. External Intercostals. (Fig. 104, 68.) Situation—Form.—These muscles fill the spaces between the ribs, but do not descend beyond their inferior extremities; they, therefore, do not occupy the intervals between the cartilages. They are flattened, fleshy bands, gradually diminishing in thickness from above to below. Structure — Attachments.—Each intercostal muscle is composed of a series of muscular fasciculi, intermixed with numerous aponeurotic fibres, both of which pass obliquely backwards and downwards, from the posterior border of the preceding to the external face of the succeeding rib. Relations.—They respond, outwardly, to the different muscles applied against the thoracic walls; inwardly, to the internal intercostals. 4. Internal Intercostals. (Fig. 106, 16.) These are placed at the internal face of the preceding, which they exactly am with regard to their general form, but from which they differ in the owi ints : 1. cg thick between the costal cartilages, these muscles are reduced at the upper part of the intercostal spaces to a thin aponeurotic layer, sup only by some fleshy fibres. They therefore gradually diminish in thickness from below upwards. 2. Their fasciculi are less tendinous than those of the external inter- costals, and are carried obliquely forward and downward, from the anterior border of the posterior rib to the posterior border and internal face of the rib in front; so that the fibres of the external and internal intercostals cross each other like the letter X. 3. Outwardly, they respond to the external intercostals; inwardly, to the costal pleura. Action of the intercostal muscles.—The function of these muscles has been for a long time, and is even now, much discussed ; and it may be said that there were never, perhaps, more diverse or contrary opinions given on any subject than on this. M. Bérard, who has summed up the elements of the discussion with the greatest judgment, considers the external intercostals as inspiratory muscles, and the internal ones also as inspiratory by those fasciculi which occupy the spaces between the costal cartilages; the remainder, the majority, are expiratory. 5. Supercostals, Synonyms.—Transverso-costales—Girard. (Levatores costarum—Percivall.) Small, flat, triangular, muscular and tendinous fasciculi, constituting, it might be said, the heads of the external intercostals, from which they are searcely distinguishable in the first and last costal intervals. _ They arise from the transverse processes of the dorsal vertebra, and are directed. backwards and outwards, gradually expanding, to terminate on the external face of the one or two ribs which suecced their fixed insertion. Outwardly, they respond to the ilio-spinalis; inwardly, to the external intercostals. The supercostals draw the ribs forward, and are consequently inspiratory 6. Triangularis of the Sternum. ms,—Sternalis—Bonrgelat. Sterno-costalis—Girard. (The slerno-costales of vall, and sterno-costalis of Leyh.) : 288 THE MUSCLES. Form — Situation.—This muscle, flattened above and below, elongated from before to behind, and dentated at its external or superior border, is situated in the thoracic cavity, above the sternum and the cartilages of the true ribs. Attachments.—It is fixed, by its internal border, on the superior face of the sternum, to the ligamentous cord which circumscribes it outwardly. It has its movable insertion on the cartilages of the sternal ribs, the first excepted, by means of digitations from its external border. Structure.—It is formed of strongly aponeurotic muscular fasciculi, which are directed from the internal to the external border. Relations.—Inwardly, with the pleura; outwardly, with the cartilages to which it is attached, the internal intercostals, and the internal thoracic vein and artery. Action.—The triangularis of the sternum concurs in expiration by depressing the costal cartilages. (Leyh asserts that if the fixed point be the sternum, this muscle pulls the ribs forwards, and so widens the thoracic cage ; but if the fixed point is the ribs, the sternum will be’raised and the thoracic space diminished.) a o DIFFERENTIAL CHARACTERS IN THE MUSCLES OF THE COSTAL REGION IN OTHER THAN SOLIPED ANIMALS, : The muscles of the costal region cannot be the same in number in all the domes- ticated animals; the intercostals and supercostals, for instance, must vary in number with that of the ribs. Beyond this, the differences are slight. In the Oz, the great serratus is very extensive, and the portion which passes to the posterior triangular surface of the scapula is readily distinguished from the anterior by its diminished thickness, the larger proportion of aponeurotic fibres it contains, and the flattened — > tendon by means of which it is inserted. In the Pig, it is remarked that the internal intercostals are prolonged, maintaining a certain thickness, to near the vertebral column, _ COMPARISON OF THE THORACIC MUSCLES OF MAN WITH THOSE OF THE DOMESTICATED ANIMALS, The muscles of the axillary region, the costal region, and the diaphragm are desig- nated in Man as the thoracie muscles. . The pectoral muscles are distinguished into great and small. The great pectoral corresponds to the superficial pectoral of the Horse. It is attached, on one side, to the inner two-thirds of the clavicle, the anterior face of the sternum, and the cartilages of the first six ribs; on the other, to the anterior border of the bicipital ve and, by a fibrous expansion, to the aponeurosis of the arm. The costal fhscicult are distinctly separated from the clavicular and sternal fasciculi. The small pectoral, which corresponds to the deep pectoral of animals, is inserted, on the one part, into the external face of the third, fourth, and fifth ribs; on the other part by a tendon to the anterior border of the coracoid process. In Man, there is found a muscle which does not exist in animals; this is the sub- clavius, a very slender fasciculus situated beneath the clavicle, and attached to the cartilage of the first rib and the external portion of the lower face of the clavicle (see _ Fig. 117, 5). The great serratus does not show any distinct aponenrosis on its surface; it arises from the eight first ribs, and its digitutions are grouped into three principal fasciculi. Lastly, in Man the internal intercostals are prolonged to the vertebral column by small muscles, named the subcostals (or intracostals). INFERIOR ABDOMINAL REGION, The lateral and inferior walls of the abdominal cavity are formed by a wide musculo-aponeurotic envelope, which rests, by its periphery, on the sternum, ribs, lumbar vertebre, ilium, lumbo-iliac aponeurosis, and the pubis. This envelope is concaye on its superior surface, and results from the assemblage of four pairs of large membranous muscles arranged in MUSCLES OF THE TRUNK. 989 2 superposed layers. Reckoning them from without inwards, these are designated the great, or external oblique, the small, or internal oblique, the gre ight, and the transverse muscle. Covered outwardly by an expan- MS eg , , a OF y °Y pen BIO of yellow fibrous tissue, the tunica abdominalis, and separated from _ those of the opposite side by the white line (linea alba), a medium raphé ex- . - tending from the sternum to the pubis, these muscles support the intestinal _ ™mass, and by their relaxation or contraction adapt themselves to the varia- ___ tions in volume these viscera may experience. ion.—After placing the animal in the first position, a wide opening is to be made in the pectoral cavity by the ablation of a certain number of ribs, which should be _ divided inferiorly, abdve the costal attachments of the great oblique muscle. The heart and are removed; then an incision is made in the diaphragm, to allow the digestive viscera contained in the abdominal cavity to be taken away. It is not abso- necessary, however, to empty that cavity, and if its contents be allowed to remain, ne _ ang ms meg vy ba Ase — ag prevent the accumulation of great distention of the abdomina preliminary precautions having been adopted, then proceed in the following u . ek ve the skin from this region, and with it the panniculus carnosus, in order to study the external surface of the abdominal tunic. 2. The dissection of the great oblique muscle is accomplished by removing the yellow fibrous envelope from the fleshy rt the muscle, together with the sterne-trochineus. The inguinal ring should exposed by the ablation of the dartus muscle, the sheath and penis, or the mamma. 3. On the opposite side, the small oblique is uncovered by excising the t oblique, _ leaving, however, that portion of the aponeurosis which is mixed up with that of the first 4. The latter having been studied, dissect the great straight muscle of the abdomen on the same side, in separating from the white line, by a longitudinal incision, _ the aponeurosis common to the two oblique muscles, dividing this aponeurosis and the >, Seep zerticn of the internal oblique by another incision extending transversely from the to the middle of the lumbar region, and laying back one of the musculo- £ sections on the thigh, the other on the ribs. 5. The transverse muscle is on the same side as the external oblique has been. To expose it, nothing more . ay than to make two incisions similar to the foregoing, but including the two _ oblique and the straight muscle, throwing back the two portions as above. 6. Lastly, __ Open the entire abdominal cavity by cutting through the transverse muscle in the same _ Way; then study the muscular digitations of that muscle, the internal orifice of the _ inguinal canal, and the leaf reflected from the apuneurosis of the great oblique muscle. fi ' 1. Abdominal Tunic. The vast expansion of yellow elastic fibrous tissue spread over the two external oblique muscles of the abdomen is so named. Very thick towards the prepubic tendon of the abdominal muscles and in the vicinity of the linea alba, this expansion gradually thins as it ap- proaches the sternum, and disappears near the abdominal insertion of the sterno-trochineus muscles. It also diminishes in thickness as it extends from the linea alba; and when it reaches the fleshy portion of the great obliqne muscle it becomes reduced to an extremely thin leaf, whose fasciculi ~ eae more and more from one another, until they completely disappear. “Anteriorly, however, it is seen to be prolonged on each side to the posterior digitations of the serratus magnus. Posteriorly, it furnishes some bundles fibres, which are detached from the surface of the common tendon, and re carried between the thighs to be lost on the internal crural muscles. The abdominal tunic is covered by the skin and the panniculus ‘earnosus, from which it is separated by an abundance of cellular tissue. In the male, its external surface gives attachment to the suspensory ligaments of the sheath, and to the dartos; and in the female, to the elastic capsule which envelops each mammary gland. By its internal face, it closely adheres to the aponeurosis of the great oblique muscle ; though it is easily A > je ue 249 ‘s THE MUSCLES, separated from the fleshy portion. It is traversed by several openings which — afford passage to the subcutaneous vessels and nerves of the abdominal on, The abdominal tunic acts as an immense elastic girth or bandage, which aids the muscles in sustaining the weight of the intestines. As the digestive organs increase in volume this tunic increases in thickness. In the Pig, Dog, and Cat, it is reduced to a simple cellulo-aponeurotic lamina, owing to the stomach and intestines in these animals exercising but a small amount of pressure on the abdom‘nal parietes. : 2. White Line. The white line (linea alba) is a fibrous cord comprised between the internal border of the two great straight muscles, and is considered as being formed by the intercrossing, on the median-line, of the aponeuroses belonging to the oblique and transverse muscles. Attached, in front, to the inferior - i. surface of the xiphoid appendage, this cord is confounded, behind, with a large tendon, the prepubic or common tendon of the abdominal muscles, which is fixed to the anterior border of the pubes (Figs. 90, a; 108, 0; 116, 4). This tendon, covered by the abdominal tunic, contributes to form the — internal commissure of the inguinal ring, and gives origin to the pubio-femoral ligament. Towards the union of its posterior third with its two anterior thirds, the white line widens, so as to form a lozenge-shaped space, in the centre of which is found the remains of the umbilicus and the umbilical cord (Fig. 116, 14). 3. Great Oblique, or External Oblique of the Abdomen. (Figs. 105, 18; 116, 5.) Synonyms.—Costo-abdominalis— Girard. (Obliquus externus abdominis—Percivall,) Situation—Composition—This muscle, the largest and the most super- ficial of the four, is composed of a fleshy and an aponeurotic portion. Form, Structure and Attachments of the fleshy portion —This is composed of fibres directed obliquely downwards and backwards, and presents itself as a wide muscular band, narrower before than behind, applied to the inferior surface of the last thirteen or fourteen ribs. Its superior border is concave, and attached: 1, To the external surface of the ribs just mentioned by as many slightly aponeurotic digitations, the first four of which cross the denta- tions of the great serratus; 2, To the aponeurosis of the great dorsal muscle, from the last rib to the external angle of the ilium (Fig. 105, 18). Its inferior border, convex and sinuous, is continuous with the aponeurosis ; it descends, in front, to the cartilaginous circle of the false ribs, which it projects beyond posteriorly, increasing in this as it nears the lumbar region. Form, Structure, and Attachments of the aponeurosis.—This is narrow and thin in front, wide and thick behind, of a triangular form, and composed of white, nacrous-looking fibres passing in the same direction as the fibres of the fleshy portion, with whose inferior border it is continuous by its external border. Its internal border is inserted into the white line and the prepubic tendon; and its posterior border, extending from the external angle of the ilium to the anterior border of the pubis, responds to the — plicature of the flank, embraces the corresponding crural muscles, and establishes the line of demarcation between the trunk and the abdominal limb (Fig. 116, 10). The aponeurosis of the great oblique gives rise, at its posterior border, to two very remarkable fibrous leaves which appear to be produced by the oz MUSCLES OF THE TRUNK. : 241 - donbling of this aponeurosis into two layers. One of these leaves descends on ' the internal muscles of the thigh to constitute the crural aponeurosis ; . 116, 11); while the other is reflected- upwards and forwards, to enter the abdominal cavity ; this reflected leaf of the great oblique aponeurosis is _ named the crural arch (ligament of Poupart or Fallopius). (Fig. 108, 8.) Near the prepubic tendon of the abdominal muscles, and immediately eel its division into two leaves, the aponeurosis of the external oblique is __- pierced by a large oval aperture (Fig. 116, 5), the inferior orifice of the canal through which passes the cord of the testicle in the male, and the . mammary vessels in the female. This channel has been named the inguinal The description of the femoral aponeurosis, the crural arch, and the inguinal ring—a necessary complement of the great oblique muscle—will be given hereafter. Relations of the Great Oblique Muscle.—By its superficial face, the external oblique responds to the sterno-trochineus and the abdominal tunic, which latter separates it from the skin and the panniculus. By its deep face, it is related to the ribs, into which it is inserted, as well as with their carti- ____ lages, the corresponding intercostal muscles, the small oblique, and the great straight muscle. The latter even appears to.be attached, through the anterior moiety of its external border, to the fleshy portion of the great oblique, by means of a slight-lamina of yellow elastic tissue, which covers, _ toasmall extent, the deep face of the two muscles. Action —The external oblique, in contracting, compresses the abdominal viscera, flexes the vertebral column, and acts as an expiratory muscle. (By its compression on the abdominal viscera it concurs in the acts of defecation, micturation, and parturition.) Iyrernat Crurat Aronevrosis.—This fibrous lamina descends from the peers of the flank on the patella and the inner surface of the leg. Outwardly, it is confounded with the aponeurosis of the fascia lata; in- wardly, it degenerates into cellular tissue. It covers the long adductor of the leg, part of the short adductor, the vastus internus, and the crural vessels at their exit from the abdominal cavity. Crurat Arca.—As already mentioned, this is the reflected leaf of the - oblique aponeurosis, and is also named the ligament of Fallopius and ‘oupart’s ligament. It is a wide, flat band, attached by its extremities to the external angle of the-ilium and the anterior border of the pubis. Its anterior face (Fig. 108; 8) forms, inwardly, the posterior wall of the inguinal canal; it gives attachment, outwardly, to the posterior fibres of the small oblique muscle, Its posterior face, applied against the superior extremity of the patellar muscles, the long adductor of the leg, the pectineus, and the erural vessels on their leaving the abdomen, embraces all these parts as in a vast arch, and from this peculiarity it derives its name. Its superior border is inserted, for its external half, into the lumbo-iliac aponeurosis. In its middle part it is much thinner, and is prolonged to the external surface of the long adductor muscle of the leg and the iliac fascia, to be’ at last mixed up with the laticr. Within the pectineal insertion of the small psoas ‘muscle, it forms the anterior margin of the crural ring: a triangular orifice _ @ireumscribed on the other side by the anterior border of the pubis, the iliacus, and the long adductor of the leg, and through which pass the crural vessels as they leave the abdomen by the crural arch! The inferior border * This orifice is covered by a very thin aponeurotic layer, which is prolonged, above, on the crural vessels, behind, into the pelvic cavity, and which appears to be continuous, K “alee A a jae -. els ks 2 nce need Sa 7 — i ee 242 THE MUSOLES, es is continuous with the femoral aponeurosis and that of the great oblique y muscle. > oe Incutnat Canat,—This is an infundibuliform canal compressed on each — ‘side, through which the spermatic cord and scrotal artery pass from the abdomen in the male, and the external mammary vessels in the female. ‘ Situated on the side of the prepubie region, in an oblique direction downwards, backwards, and inwards, and measuring from two to two-and- a-half inches in length, this canal lies between the crural arch, which con- stitutes its posterior wall, and the fleshy portion of the small oblique muscle, which forms the anterior wall. Its inferior (external) or cutaneous orifice, also named the inguinal ring, is much larger than the superior (internal). Pierced in the aponeurosis of the great oblique, in the angle formed by the union of the internal border _ with the posterior border of the aponeurosis, this opening is of an oval form, directed obliquely backwards and inwards, which permits it to be described as having two lips or pillars, and two extremities or commissures. The pillars, distinguished into anterior and posterior, are composed of the arciform fibres from the aponeurosis of the great oblique muscle. tue The commissures, internal and external, result from the union of the two pillars at their extremities. The internal is limited by the prepubic tendon of the abdominal muscles. The superior (internal) or peritoneal orifice of the inguinal canal is situated — in front of, and directly opposite to, the crural ring. 1t is a simple dilatable slit, comprised, like the canal itself, between the crural arch and the small oblique muscle. Not well defined at its extremities, this opening includes the neck of the vaginal sheath. 4. Small or Internal Oblique Muscle of the Abdomen. (Figs. 106, 17’; 116, 2.) Synonyms.—Tlio-abdominalis—Girard. (Obliquus internus abdominis—Pereivall.) Situation—Composition.—Situated beneath the preceding, which exactly covers it, this muscle is, like it, composed of a fleshy and aponeurotic ortion. ‘ 3 Form, Structure, Position, and Attachments of the muscular portion—The muscular portion is very thick, triangular, and flabelliform, and oceupies the region of the flank. Its superior border is united, by a thick, yellow, elastic production, to the aponeurosis of the great dorsal (latissimus dorsi), and a peculiar small muscle, named by the Germans the retractor coste (retractor of the last rib), which we consider as a dependency of the small oblique muscle. Its posterior border is slightly raised and lies against the crural arch, from which it separates, inwardly, to form the inguinal canal. Its anterior and inferior border is convex, irregular, and thinner than the other portions of the muscle, and is continuous with the aponeurosis. All the fibres entering __ into the composition of this muscular portion are spread like a fan, and leave the external angle of the ilium and the external fourth of the crural arch to be directed, the posterior fibres backwards and inwards, the middle fibres downwards, and the anterior fibres forwards to reach the antero- inferior border of the muscle. t id o 4 P inferiorly, with the upper border of Poupart’s ligament, This lamina is perhaps only a dependency of the subperitoneal aponeurosis; and if so, it represents the only vestige of the fascia transversalis it has been possible to discover in Solipeds. | if £ Y ; : ‘ ¢ > i 4 1% z : —This is a wide and powerful muscular band, extending from the sternum _ to the pubis, included between the aponeurosis of the internal oblique and - - z ' , directed like the muscular fibres, and cross - in X fashion the aponeurotic fibres of the external oblique. It succeeds the an- _tero-inferior border of the muscular por- ‘tion, and is separated, superiorly, into ‘several digitations which reach the in- ternal face of the last asternal cartilages. Throughout the whole extent of its in- ternal border it is fixed to the white line. _ Relations—This muscle is covered the external oblique. The aponeuroses the two muscles, which are merely superposed outwardly, are blended in- wardly in so intimate a manner that it might be thought their respective fasci- culi were woven into each other. The small oblique covers the great straight and the transverse muscles. Action.—This muscle, a congener of © the preceding, compresses the abdominal viscera, depresses the last ribs, and causes the flexion, either direct or lateral, of the vertebral column. The retractor muscle of the last rib.— This small muscle, flattened on each side, and triangular in form, originates by a fibres from the summits of first two or three transverse processes of the lumbar region. It terminates on the ior border of the last rib. Covered by the last digitation of the pos- terior serratus and by the great oblique, it covers in turn the transverse muscle of the abdomen. In contracting, it draws the last rib backwards, and fixes it in that position, in order to permit the ex- piratory action of the internal intercostal muscles. It therefore plays the same part, in regard to these muscles, that the sealenus does to the external intercostal muscles (Fig. 106, 17). 5. Great Rectus Muscle of the Abdomen. (Figs. 105, 20; 116, 3.) oo! epee (Ree- inis—Percivall.) Situation—Extent — Form—Structure. es MUSCLES OF THE TRUNK. 243 Form, Structure, and Attachments of the aponeurosis.—The aponeurosis is irregularly triangular, and formed of nacrous.looking fibres, which are MUSCLES OF THE INFERIOR ABDOMINAL REGION, 1, Aponeurosis of the great oblique; 2, Muscular portion of the small oblique ; 3, Rectus abdominis; 3’, Transverse muscle; 4, Flat tendon by which the four abdominal muscles are inserted into the pubis; 5, Inguinal ring; 6, Its anterior pillar; 7, Its posterior pillar; 8, Its external commissure; 9, Internal commissure; 10, Posterior border of the great oblique aponeu- rosis; 11, Internal crural aponeurosis ; 12, Strip of the great oblique aponeu- rosis turned downwards to show the origin of Poupart’s ligament; 14, Traces of the umbilicus. that of the transverse muscle, narrower at its extremities than in its middle portion, and divided by numerous. transverse and zig-zag fibrous inter- ” the digit (flexing the hock, and probably keeping the tendons tense. Rumrvants.—The 1 is the only muscle in the region of the foot met with in Ruminants. It is attached, inferivrly, to the tendon of tlie common extensor and that of the proper extensor of the internal digit. .—This animal possesses: 1, A pedal muscle attached, below, to the two branches of the common extensor of the large digits : 2, Four interosscous metatarsal muscles, which do tet appear to differ in their general arrangement from the metacarpal interosseous muscles. Carntvorna.—In the Dog and Cat there exist in the region of the posterior foot : 1. A pedal muscle, composed of three fasciculi which have their origin either from the inferior extremity of the os calcis, or from the tendinous sheaths in the bend of the hock; they terminate on the second, third, aud fourth digits by small tendons joined to the branches of the common extensor. : 2. The muscular digitations annexed to the tendon of the perforatus, traces of the fleshy phone of the flezor brevis digitorum of Man. 3. pedis accessorius, or perforans, a small undevelo muscle commencing outside tarsus, and terminating by a very delicate aponeurosis on the posterior fage of the perforans tendon. Two or three pale and rudimentary bands, situated inside the tarsus and near the internal digit. These are the vestiges of the muscles proper to the ¢ toe in Man. 5. An adductor of the little toe (abductor minimi digit) is a thin, elongated muscle, earried obliquely from the posterior tarso-metatarsal ligament to the internal side of the first phalanx of that digit. 6. Four interosseous metatarsal muscles, resembling the analogous muscles of the meta le é eine Toeabrte, sivailer to those of the anterior limb. COMPARISON OF THE MUSCLES OF THE FOOT IN MAN WITH THOSE OF ANIMALS. 4n Man, there are distinguished the muscles of the dorsal region, the plantar region, and the interosseous muscles. A, Dorsal Region. This only contains one muscle, the pedal (extensor brevis digitorum), It is attached, behind, to the antero-external part of the upper face ot the os calcis by several aponeurotic laminw ; its fleshy fasciculi, four in number, are prolonged by as many tendons destined to the first four toes; three of them pass along with the tendons of the common extensor, 312 THE MUSCLES. B. Plantar Region. This is subdivided into three regions: a middle, internal, and external, The first comprises: 1. The common short flexor of the toes which is represented in Solipeds by a portion of the perforatus. Itis attached to the infero-internal cee So ; the os calcis, and.to the upper face of the middle plantar aponeurosis. It is follo hy four tendons, which are inserted into the second phalanges of the first four toes, after forming rings through which pass the tendons of the common long flexor. ; 2. The accessory of the long flexor, whose fibres pass to the tendons of the common flexor 3. The lumbrici, four in number, and analogous to those of the hand. The internal plantar ee is composed of three muscles, which are found in w rudimentary condition in the Fig. 141. Fig. 142. FIRST LAYER OF PLANTAR MUSCLES OF THIRD AND PART OF SECOND LAYER OF ; _ HUMAN FOOT, “PLANTAR MUSCLES OF HUMAN FOOT, 1, Os caleis; 2, Posterior part of plantar 1, Incised plantar fascia; 2, Musculus acces- fascia divided transversely; 3, Abductor sorius; 3, Tendon of flexor longus digi- pollicis; 4, Abductor minimi digitii; 5, torum ; 4, Tendon of flexor longus pollicis ; Flexor brevis digitorum; 6, Tendon of 5, Flexor brevis pollicis; 6, Adductor pol- flexor longus pollicis; 7, 7, Lumbricales. licis ; 7, Flexor brevis minimi digitii; 8, Transversus pedis; 9, Interossei muscles, plantar and dorsal ; 10, Convex ridge formed by tendon of peroneus longus in its oblique course across the foot, 1. The short adductor of the great toe, which extends from the internal tuberosity of the os calcis to the internal sesamoid and the first phalanx of the great toe. 2. The short flexor of the great toe, which arises from the third cuneiform and the tendon of the posterior tibial, and terminates by two branches on the external sesathoid and the internal sesamoid of the great toe. 3. The short adductor of the great toe, a muscle formed by two fasciculi, and having a common termination on the external sesamoid. One of these fasciculi arises from the inferior face of the cuboides, the third cuneiform, and the base of the third and fourth metatarsal ; it has been formerly described as the oblique adductor. '‘U'vhe other has its origin from the inferior face of the three last metatarso- -phalangeal articulations ; this has also been called the transverse adductor, MUSCLES IN BIRDS, 313 The external gle lantar region likewise comprises three muscles, which are : short abductor of the little toe, which is detached from the internal tuberosi eae, of the 0s culcis, and is inserted into the external portion of the first phalanx of the li The short Y coed of the little toe is attached, behind, to the sheath of the long reat and atin Ite te. of the fifth metatarsal ; in front, to the external part of the e little toe. 8. The eee of the little toe, concealed beneath the preceding, is inserted at one end to sheath of the long peroneus, aud at the other to the external border of C. Interosseous Muscles. “These are divided into dorsal and plantar interossei, Their disposition is nearly - the same as in the hand. CHAPTER ITI. THE MUSCLES 1N BIRDS. In birds we find the maj rity of the muscles already described ; though they are appro- priate by their form, — arrangement, etc., to the particular conformation of the _ skeleton in nedigaire animal. To undertake, in this essentially practical work, a special description of all these organs, would be to depart from the object aimed at ; and we therefore confine ourselves _ to those points which present most interest in an animal mechanic point of view. 1, Tendons —The tendons in birds present in the inferior limbs and at the extremity of the wings an amount of ossification more or less extensive along their course. This of the fibrous tissue of the muscles is not the effect of senility, for it is _ noticed in very young animals. The tendons, in losing the greater part of their elasticity, doubtless gain in tenacity ; and this allows them to transmit to “pea an levers the muscular efforts in a more manner. vertebrae are echoed, by a multitude of filiform lot i. all directed rebate 5 r and which have originated from the ossification of the tendinous fibrille annexed to the muscles of the cervical region. 2. The Pectoral Muscles.—The two alternative movements which produce flight—the elevation and depression of the wings—being due to the action of the pectoral ‘muscles, saa merit eal ae. alae neem great pectoral, “ which alone weighs heavier than all the other the bird a P vogether, is attached to the furculum, to the great ridge of the > sel and to the last ribs; it is inserted into the very salient rugged outline of the humerus. It is by this muscle that birds are able to give those powerful strokes of the which are necessary in flight.” deep or small is “ placed in the angle formed by the body of the sternum and its crest, and in the intecrad between the furculum and the coracoid bone. Its tendon tg the foramen formed by the union of the fureulum, the coracoid and la, as over a pulley; it is inserted abuve the head of the humerus, it ota t is by means of this arrangement that nature has been able to place an elevator and Pn ressor at the inferior surface of the trunk so far from the centre of _ Bravity, without which the bird would have been liable to lose its equilibrium and tumble over head foremost in the air.' mn Caiet, ado lopting the nomenclature of Vicq-d’Azyr, called this muscle the middle gave the name of small pectoral to a triangular fasciculus which leaves ietenl a angle of the sternum and the Line of the coracoid bone, to be iuserted under * Cuvier, ‘ Legons d’Anatomie Compareée.’ 314 . THE MUSCLES. the head of the humeius. In our opinion, this tendon does not belong to the yp region, but to that of the shoulder; and with J. F., Meckel we ore inlipeaye con as the coraco-humeralis, which has followed the coracoid process in ate 98 3. The Diaphragm.—* In birds, the diaphragm is so different] it is in the higher vertebrata, that its existence has been successively anal fond gale understood, itted and refuted, and is still looked upon as problematical wd number of anatomists. Nevertheless, this muscle exists, and its conan is i perfect harmony with the importance of its functions. It is composed which at their origin are confounded with each other, but soon become pursue, one a transverse, the other an pag Oe direction. The transverse mer g triangular in form, and is carried horizontally from the riglit to the left ribs inferior surface of the lungs. The oblique plane is convex in front, concave extends from the dorsal aspect of the spine to the sternum, dividing the cavity trunk into two secondary cavities—the thorax and abdomen. “In birds, as in mammals, the diaphragm is therefore intended to perform two mild - functions; but to do tliis perfectly in the former, it is doubled. So far, then, > inspiratory muscle being absent in birds, or from its existing in a rudimentary hick n they are really vided with two diaphragms: 1, A ; presides in the dilatation of the lungs; 2, A thoracic abdominal dia hragm, W r- titions the great cavity of the trunk, and concurs in the inspiration of the air by ! a the large wrial reservoirs lying at its posteriur surface. Of these two muscular Le z the first is analogous to that portion of the diaphragm which, in Man and the rpg oe into the sternum and the rib.; the second manifest! y represents the pia of the diaphragm.” - This description, taken from tlie work of M. Sappey, an nee who is as conseiene -4 tious as he is talented, gives a perfectly exact idea of cris tome |’ 2... Geoffroy Saint-Hilaire, in his memoir on the bones of the sternum (‘ P Anatomique,’ vol. i. p. 89), in comparing the pectoral muscles of fish to those of also employs the nomenclature of Vieqd’ Azyr, and recognises three pectorals as was We are, however, obliged to confess ourselves as in opposition to the great master who has established rules to follow in the classification of or, in consequence of his — having limited his com ms to the two classes of vertebrata he had principally in view. If he had extended his observations to the mammalia, and, in them sought for the analogue of the pectoralis parvus, he would have discovered it, as we have done, i in the © region of the shoulder, and not in that of the sternum. 7 | [ 315 j CHAPTER IV. GENERAL TABLE OF THE INSERTIONS OF THE MUSCLES IN SOLIPEDS. 1. Vertesrat Coiumy. A. CERVICAL VERTEBRAE, I. Atlas. The atlas gives insertion to nine pairs of muscles :— a. By the surface representing the spinous process, to the— Small posterior recti muscles of the head. b. By its transverse processes, to the— 1, Splenius muscles, 2. Small complexus muscles. 3. Great oblique muscles of the head. 4. Small oblique muscles of the head. 5. Mastoido-humeralis muscles. ce. By its body, to the— 1. Small anterior recti muscles of the head. ‘a 2. Small lateral recti muscles. 8. Long muscle of the neck. Il. Azis. The axis gives insertion to six pairs of muscles :— a. By its spinous process, to the — 1. Transverse spinous muscles of the neck. 2. Great oblique muscles of the head, 3. Great posterior recti muscles of the head. e b, By its transverse processes, to the— 5 1. Intertransverse muscles of the neck. 2. Mastoido-humeralis muscles, And by the inferior face of its body, to the— 3. Long muscle of the neck. IIL. Third, Fourth, Fifth, Sixth, and Seventh Cervical Vertebrx. These vertebre give insertion to the following muscles :— a. By their spinous processes, to the— 1, Transverse spinous muscles of the neck. 2. Llio-spinalis muscles (4th to the 7th). b. By their articular tubercles, to the— 1. Great complexus muscles. 2. Small complexus muscles. 8. Transverse spinous muscles of the neck. 4. Intertransverse muscles of the neck. ¢. By their transverse processes, to. he— 1. Angular muscles of the scapula. 2. Splenius muscles (3rd and 4th). 3. Mastoido-humeralis muscles (3rd and 4th). 4. Common intercostal muscles (7th). 5. Intertransverse muscles of the neck. 6. Ilio-spinalis muscles (inferior branch). 316 THE MUSCLES. And by the inferior faces of their bodies, to the— ie Great anterior reeti muscles Of the heed. 2. Long musele of the neck. _ B. DORSAL VERIEBRAS, The dorsal vertebrae give poi he a. By their spinous processes, to the— : . Splenius muscles (ist to 5th or 6th). . . Great complexus muscles (1st to ay . Small complexus muscles (1st and 2nd), Trapezius muscles. Great dorsal muscles (4th to 18th). Rhomboid muscles (2nd to 7th). . Small anterior serrated muscles (2nd to 13th Small posterior serrated muscles (10th to 18th). . Ilio-spinalis muscles, Transverse spinous muscles of the back and loins. b. By their transverse processes, to the— 1. Great complexus muscles. 2, Small complexus muscles. 3. Tlio-spinalis muscles. 4. Transverse — muscles of the back and luins. 5. Supercostal musel c. By their bodies, to reas 1. Long muscle of the neck (ist to 6th). 2. Great psoas muscles (17th to 18th). 3. Small psoas muscles eee to se UR 2 1 _ SOHIS ©. LUMBAR VERTEBRA, The lumbar vertebre give insertion ;— a. By their spinous processes, to the— 1. Great dorsal muscles. 2. Small posterior serrated tauscles (1st to 3rd). 3. Ilio-spinalis muscles. 4, Transverse spinous canis of the back and loins. b. By their articular tubercles, to the— 1. Llio-spinal muscles. » 2. Transverse spinous muscles of the back and ‘ola c. By their transverse processes, to the— 1. Great psoas muscles. 2. Square muscles of the loins. 8. Intertransverse muscles of the loins. 4, Transverse muscles of the abdomen, 5. Tlio spinalis muscles. d, By their bodies, to the— 1. Great psoas muscles. - 2. Small psoas muscles, 3. Pillars of the diaphragm, D, SACRUM, The sacrum gives insertion to the— 1. Ilio-spinalis muscles. 2. Pe ty spinous vec ite of the back and loins. 3. sacro-coccy, muscles, 4. Lateral sacro-coceygeal muscles, 5. Inferior sacro-coccygeal m GENERAL TABLE OF MUSCULAR INSERTIONS. 6. Ischio-coceygeal muscles, 7. Long vasti muscles. 8. tendinosus muscles. 9. Internal obturator muscles. E COCcYxX. — The coceyx gives insertion to the— 1. Superior sacro-coccygeal muscles. 2. Tnboriee sacro-coccygeal muscles, 3. Lateral sacro-coccygeal muscles 4, Ischio-coccygeal muscles (1st and 2nd cocey goal vertebriv ). 2, Heap. A. BONES OF THE CRANIUM. I. Occipital. The occipital gives insertion to nine pairs of muscles :—_ 1. Great complexus muscles, ; 2. Small oblique muscles of the head. 3. Great posterior recti muscles of the head. 4. Small posterior recti muscles of the head. 5. Great anterior recti muscles of the head. 6. Small anterior recti muscles of the head. 7. Small lateral recti muscles... 8. Digastric muscles, 9. Occipito-styloid muscles. II. Parietal. The parietal gives attachment to one muscle :— The temporal. Ill. Frontal. The frontal gives insertion to the— Supernaso-labialis. IV. Sphenoid. The sphenoid gives attachment to four muscles : — 1. Great anterior recti muscles of the head. 2. Small anterior recti muscles of the head. 3. Internal pterygoid muscles. 4, External pterygoid muscles. V. Temporal. _ ‘The temporal gives insertion to five muscles :— 3. Small oblique musele of the head. : . Mastoido-|liumeralis. 5. ‘l'emporal. B. BONES OF THE FACE. I. Superior Maxillary. ‘The supermaxillary gives insertion to the following muscles : — 1, Cuticularis of the neck. 2. Alveoli-labialis. 317 See yee ee ae jae “ t., ‘y me ~~) ai THE MUSCLES. = == 3. Supermaxillo-nasalis. ‘a 4, Great supermaxillo-nasalis. a 5. Masseter. ‘ = ae Il. Premazxillary Bone. Ls The premaxillary bone gives insertion to the— 1. Small supermaxillo-nasalis. 2. Anterior middle or intermediate muscle. Ill, Palatine Bone, The palatine bone gives insertion to the— Internal pterygoid muscle. IV. Zygomatic. - The zygomatic bone gives insertion to one muscle, the— Supermaxillo-labialis. c err V. Lachrymal. The lachrymal bone gives insertion to one muscle, the— Lachrymo-labialis, VI. Nasal Bone, The nasal bone gives insertion to one muscle, the— Supernaso-labiulis, VII. Inferior Mavilla. ; The inferior maxilla gives insertion to the following muscles ant . Sterno-maxillaris. . Alveolo-labialis. . Maxillo-labialis. . Posterior middle or intermediate muscles. — Masseter muscles, Temporal muscles, Internal pterygoid muscles. . External pterygoid muscles. . Digastric muscles, 10. Mylo-hyoid muscle. 11, Genio-hyoid muscl s. $I Ste SS 0. HYOID BONE. The hyoid bone gives insertion to the following muscles :— a, By its body and its thyroid cornua— / 1. Seats muscles. 2. Scapulo hyoid muscles. “8. Mylo-hyoid muscles. 4, Genio-hyoid muscles, 5. Stylo-hyvid muscles, 6. Kerato-hyoid musel 8, 7. Transverse muscle of the hyoid bone. b, By its branches (styloid cornua and styloid bones)— a; heating te muscles. 2. Kerato-hyoid muscles. 8. Occipito-styloid muscles, GENERAL TABLE OF MUSCULAR INSERTIONS. 319 8. Bones or tHe THorax. er A, THE RIBS AND THEIR CARTILAGES, The ribs and costal cartilages give insertion to the-— . 1. Sealenus (1st). 2. Small anterior serrated muscle (5th to 9th). 3. Small posterior serrated muscle (9th to 18th), 4, Ilio-spinalis muscle (3rd to 18th), 5, Common intercostal muscle, 6. Great psous (17th to 18th). 7. Square muscle of the loins (16th to 18th). 8. Great serrated muscle (1st to 8th). 9. Transverse muscle of the ribs (Ist). 10. External intercostal muscles. 11. Internal intercostal muscles, 12. Supercostal muscles. + 13. Triangular muscle of the sternum (2nd to Sth). 14. Great oblique muscle of the abdomen (5th to 18th). 15, Small oblique muscle of the abdomen (asternal ca: tilages). 16. Great rectus muscle of the abdomen (asternal cartilages). 17. Transverse muscle of the abdomen, 18, Diaphragm (7th to 18th). B, STERNUM, The sternum gives insertion to the— 1. Cuticularis of the neck. 2. Sterno-maxillary muscles. 8. Sterno-thyroid muscles. 4. Sterno-hyoid musvles. 5. Superficial pectoral muscles. 6. Deep pectoral muscles. 7. Transverse muscles of the ribs. 8, Triangular muscle of the sternum, 9. Great recti muscles of the abdomen. 10. Transverse muscles of the abdomen. 11. Diaphragm. 4. Tuoracic Liu. A. BONES OF THE SHOULDER. Scapula. The scapula gives insertion to seventeen muscles :— a. By its external face to the— 1, Supraspinatus. 2. alaokiatue, 8. Short abductor of the arm, or teres minor. 4, Long abductor of the arm. 5. Trapezius 6. Mastoido-humeralis. b. Ry its internal face, to the— 1. Rhomboid muscle. 2. Angular muscle of the scapula. 8. Great serrated muscle. 4, Subscapularis. 5. Small scapulo-humeral muscle. ¢. By its anterior border, comprised between the cervical angle and the coracoid process, to the— 1, Sterno-prescapularis, or small pectoral muscle. WHE MUBOLES. 2. Lon flexor of the fore-arm, or brachial biceps. 38. Corseo-bessliiht muscle, — 4. Supraspinatus muscle, d, By its Boot eusais:i8 border, pie the dorsal angle an ion of the humeral angle, to the— dine aaa of the fore-arm. Brey haar, am uctor o or teres 4. Long al-ductor of the arm, 5. Short abductor of the arm. B. BONES OF THE ARM. Humerus. The humerus gives insertion to twenty-four muscles :— a, By its superior extremity, to the— 1. Supraspinatus. 2. Subspinatus, 3. Subscapularis, 4, Small seapulo-humeralis. 5. Sterno-trochineus, or deep pectoral. 6. Panniculus carnosus, b, By its body, to the— 1. Long abductor of the arm. . 2. Short abductor of the arm. . Coraco-brachial muscle by two points. . Adductor of the arm, or teres major, Short flexor of the fore-arm, or anterior brachial muscle. Short extensor of the fore-arm, . Middle extensor of the fore-arm.. ‘ Small extensor of the fore-arm, or anconeus muscle, . Anterior extensor of the metacarpus. 10. Anterior extensor of the phalanges. 11. Great dorsal muscle. ; 12. Mastoido-humeralis muscle. 13, Sterno-humeralis, or superficial pectoral muscle. c. By its inferior extremity, to the— 1, Anterior extensor of the phalanges. 2. External flexor of the metacarpus. . 3. Oblique flexor of the mefacarpus. 4. Internal flexor of the metacarpus, 5. Superficial flexor of the phalanges, or perforatus. 6. Deep flexor of the phalanges, or perforans. __ SW 1S Ere Go ©. BONES OF THE FORE-ARM. I, Radius. The radius gives insertion:— a. ser its upper extremity, to the— 1. Long flexor of the fore-arm, or brachial biceps. 2. Anterior extensor of the halanges, . 8. Lateral extensor of the b. By its body, to the— 1. Short flexor of the fore-arm, or anterior brachial muscle. 2. Oblique extensor of the metacarpus 8. Anterior extensor of the halanges. 4. Lateral extensor of the p. ges. 5. Deep flexor of the pisenees, or perforans, GENERAL TABLE OF MUSCULAR INSERTIONS. 821 ; 3 ‘ II. Ulna. oe | ‘The ulna gives insertion :— a. By its wpper extremity (olecranon) to the— 1, Long extensor of the fore-arm, = a extensor of the forearm. Short extensor of the fore-arm. ri Middle extensor of the fore-arm. 5. Small extensor of the fore-arm, or anconeus muscle. 6. Oblique flexor of the metacarpus. 7. Deep flexor of the phalanges, or perforans. b. By its body, to the— 1. Short flexor of the Risasis, or anterior brachial musole. 2. Lateral extensor of the phalanges. a D. BONES OF THE CARPUS, Supercarpal Bone. The superearpal bone, the only bone of the carpus which has muscular attachments, gives insertion to two muscles :— 1. External flexor of the metacarpus, or posterior ulnar. 2. Oblique flexor of the metacarpus. BE, BONES OF THE METACARPUS. I. Principal Metacarpal. The satanigal metacarpal gives insertion to a single muscle :— By its superior extremity, to the— Anterior extensor of the metacarpus. Il. External Rudimentary Metacarpal. This gives insertion to a single muscle :— External flexor of the metacarpus, or posterior ulnar. III. Internal Rudimentary Metacarpal. This gives insertion to two muscles :— 1. Oblique extensor of the metacarpus. 2. Internal flexor of the metacarpus, or great palmar muscle. F. BONES OF TRE DIGITAL REGION. I, First Phalanz. This gives insertion to two muscles :— 1. Anterior extensor of the phalanges. 2. Lateral extensor of the phalanges. II. Second Phalanz. This gives insertion to two muscles :-— 1, Anterior extensor of the phalanges. 2. Superficial flexor of the phalanges. Ill. Third Phalanz. The third phalanx, or os pedis, gives insertion to two muscles :— 1. Anterior extensor of the phalanges. 2. Deep flexor of the phalanges. a. By the ilium, to the— b. By the pubis, to the— 7s e. By the ischium, to the— The femur gives insertion :— a. By its upper extremity, to the—- b. By its body, to the— » fo © oO .s a > a? a ee, : ae i eae . . Pod ¢ _ THE MUSCLES. : = s err LOK) 5. AppominaL Lins. - ou A. BONES OF THE HAUNCH. a Coxa, A eae The coxa gives insertion :— ae 1, Tlio-spinalis muscle. 2. Iliac (psoas) muscle. 3. Small pseas muscle. 4. Square muscle of the loins. 5. Ischio-coceygeal muscle. 6. Great oblique muscle of the abdomen. 7. Small oblique muscle of the abdomen. 8. Transverse muscle of the abdomen (through the medium oft arch), 9. Middle gluteal muscle, 10. Deep gluteal muscle, 11. Muscle of the fascia lata. +: oe 12. Anterior rectus muscle of the thigh. ' Fi 13. Anterior gracilis muscle. hie 14, Internal obturator, 1, Great oblique muscle of the abdomen. 2. Small oblique muscle of the abdomen, 3. Great rectus muscle of the abdomen. 4, aaesetniat muscle of the abdomen (through the medium of the er ) 5. Short adductor of the leg. 6. Pectineus muscle. 7. Small adductor of the thigh. . External obturator muscle. 9. Internal obturator muscle. 1, Superficial gluteus muscle, 2. Long vastus muscle, 3. Semitendinous muscle. 4. Semimembranous muscle. 5. Short adductor of the leg. sy 6. Great adductor of the thigh. 7. Square crural muscle. Soo ge 8. External obturator muscle, = 9. Internal obturator muscle. 10. Gemelli muscles of the pelvis. B., BONES OF THE THIGH. Femur. 1. Great psoas muscle, 2. Tliac psoas muscle. 8. Middle gluteus muscle, 4, Deep gluteus muscle, 5. External obturator muscle, 6. Internal obturator muscle. 7. Gemelli muscles of the pelvis. 1. Superficial gluteus muscle, 2. Fascia lata, ‘GENERAL TABLE OF MUSCULAR INSERTIONS. 823 , _ 8. External vastus muscle (crural triceps). ss 4. Internal vastus muscle are triceps). * 5. Anterior gracilis muscl _ a 6. Long vastus muscle. ie Pectineus muscle. ae 8. Small adductor of the thigh. 9, Great adductor of the thigh. 10. Square crural muscle. | 2 11. Gastrocnemii muscles. - 12. Superficial flexor of the phalanges, or perforatus, ¢e. By its inferior extremity, to the— 1, Semimembranous muscle. 2. Great adductor of the thi 3. Anterior extensor of the phalanges. 4. Flexor of the metatarsus. 5. Popliteus muscle. C, BONES OF THE LEG. I. Tibia. The tibia gives insertion :— a. By its upper extremity, to the— 1. Flexor of the metatarsus. Aspe amen flexor of the phalanges, or perforans. ; 4. t Obljes flexor of ee 5. Long adductor of pe leg (through the medium of the internal patellar ligament). . b, By its body, to the— 1. Long vastus muscle. 2. Semitendinous muscle. 3. Short adductor of the leg (in common with the long adductor). 4. Flexor of the metatarsus. 5. Popliteus muscle. 6. Deep flexor of the phalanges or perforans, IL. Fibula. SEMI Gisela givce inecrtion to two tuscles — 1, Lateral extensor of the phalanges. 2. Deep flexor of the phalanges or perforans. Il. Patella, Tho patella gives insertion tf muscles :— 1, Fascia lata muscle (or tensor vaginz). 2. Anterior rectus of the thigh. 8. External vastus (crural triceps). 4. Internal vastus (crural triceps). 5. Long vastus muscle. D, BONES OF THE TARSUS. Caleis. ‘The calcis gives insertion to the :— : ’ Gastrocnemii muscles. 4 "yd Cuboides. _ The cuboides gives insertion to the— Flexor-of the metatarsus. we e = - ’ .-- aes yess - iia = Fah ’ ‘ Te ae a > “a ee Pe a. hbals 7" We aid 3 This gives attachment to the— > Flexor of the metatarsus, B. BONES OF ‘THE METATARSUS. The principal metatarsal gives insertion to the— Flexor of the metatarsus, . BONES OF THE FOOT. I. First Phalanx. The first phalans gives ineersios $0:Aueeeeer oo Anterior extensor of the phalanges. ' “IL, Second Phalanz, The second phalanx gives insertion to two muscles a Anterior extensor of tbe phalan, 2. Superficial flexor of the Phalanges, or perforatus. TIL, Third Phalanz. | The third phalanx gives insertion to two muscles :— 1. Anterior extensor of tle phalanges. 2. Deep flexor of the phalanges, or perforans. ¢ = - { 325 } BOOK I. THe DIGESTIVE APPARATUS. CHAPTER I. GENERAL CONSIDERATIONS ON THE DIGESTIVE APPARATUS. We have considered the animal as a machine composed of various levers and susceptible of various movements; but it will be easily under- stood that the working of this machine will cause the wear or decomposition of the molecules which enter into the construction of its organs, and that these springs or animated wheels demand for their maintenance an incessant supply of new materials, destined to repair their continual losses, therefore, are under the necessity of taking aliment, from which they extract those reparative principles which, distributed to all the organs, are assimilated into their proper substance. The organs in which this work of preparation and absorption of the organisable material is carried on are collectively named the digestive : one of the most important of those which, as we will see, suc- cessively complicate and perfect the animal machine. This apparatus does not, y speaking, constitute an essentially distinctive characteristic of *animality, as there are animals without a digestive cavity ; but it is yet one of the most salient attributes, for the exceptions just mentioned are ex- tremely rare. Considered in the vertebrata, this apparatus appears as a long tube, most frequently doubled on itself many times, bulging at intervals, and provided along its course with several supplementary organs, the majority of which are of a glandular nature. This tube extends the whole length of the animals body, and opens externally by two orifices, one of these serving for the introduction of aliment, the other for the expulsion of the residue of digestion. These openings are at the extremities of the alimentary canal. The conformation of this apparatus is not identically the same in all the individuals composing the sub-kingdom of vertebrata ; on the contrary, it presents very numerous varieties, according to the habits and mode of life of these individuals, and this makes its study interesting from two ints of view : in relation to the scienco of zoology, and to that of veterinary iene, which derives from this study valuable indications concerning the of the domesticated animals. But this diversity of characters does not suffice to establish sharply- defined limits between the conformations that are distinguished by it. There is, in reality, but one typical form for the digestive apparatus, and the same principle prevails in its construction throughout the entire series, Thus, whichever of the vertebrata we may be studying, its alimentary tube will be found composed of a collection of bulging or tubuliform cavities, which succeed each other from before to behind in the following order: the mouth, pharynx, esophagus, siomach, and intestine. 826 GENERAL CONSIDERATIONS ON THE DIGESTIVE APPARATUS. This system of cavities is divided, physiologically, into two principal sec- tions: the first comprises the mouth, pharynx, and cesophagus, oF the compart- aa ments in which are carried on those digestive operations term because they prepare the aliment for the subsequent wmodifeadeaea which constitute the essential phenomena of digestion; the second section is formed by the stomach and intestine, where these phenomena take place. Each of these two sections is furnished in its course with annexed a which are present in the majority of vertebrata; these are the salivary glands for the cavities of the first category, and the liver, pancreas, and spleen for those of the second. In considering the general position of these various parts, principally in mammals and birds, it is found that the first section of the digestive canal and its appended organs is lodged beneath the upper jaw and the base of the cranium, and under the cervico-thoracie portion of the vertebral column. The second section, with its annexes, occupies the great abdominal cavity. In Man, these two sections are divided into supra-diaphragmatic and infra-diaphragmatic, because of their relations to the diaphragm. The constituent parts of the first category might be termed, by reason of their functions, the preparatory organs of the digestive apparatus ; and those of the second, or abdominal portion, the essential organs of digestion. These various organs, with those composing the respiratory and genito- urinary apparatus, have received the name of viscera, and the term splanch- nology is often given to that branch of anatomy devoted to their study.? These new organs differ so notably from those already described, that it is necessary to enter into some generalities as to their nomenclature, dis- position, form, structure, and physical or chemical characteristics. Nomenclature in splanchnology does not rest on any scientific basis ; the name of organs being sometimes derived from their form—as the amygdalee ; 4 sometimes from their direction—rectum ; sometimes also from their uses—the esophagus, salivary glands ; their length—duodenum ; the names of the anato- mists who have described them—the duct of Stenon, Fallopian tube ; and at times these names are purely conventional, as the spleen, They are distinguished as hollow and solid organs. 1. The hollow organs have a more or less considerable cavity, sapatits of being increased or diminished, but they are not of a definite shape or volume. Their consistency varies with their state of plenitude or vacuity, and they are single or double, symmetrical or asymmetrical. Tn all cases, the walls of the hollow organs are composed of two or more membranes which we will now describe in a general manner. a, The innermost is called the mucous MEMBRANE, because of the mucus with which its free surface is always covered. It is made continuous with the skin at the natural openings; and from its similarity of organisation it has been named the internal or re-entering skin, or internal tegumentary membrane. 1 The name of viscera (from vescor, I nourish) has been given to the organs which aid in nutrition, and the term Splanchnology (from omyd4xvov, a viscus or intestine) has been bestowed on that division of anatomy which treats of these organs. Splanchnology, thus understood, comprises the study of the digestive, respiratory, urinary, and cire apparatus. But the description of the latter forms a separate category, designated in the language of the schools by the name of Angiology. On the other hand, however, several authorities include in Splanchnology the organs of generation, and others even add the ns of sense. There is, therefore, no accord in the limits given to the definition of Spletchnalbey ; and this being the case, we have thouglit it best to omit this expression mr the distinction it seeks to establish. GENERAL CONSIDERATIONS ON THE DIGESTIVE APPARATUS. 827 *_ A mucous membrane comprises a superficial or epithelial layer and a Ds portion which constitutes the derm or chorion (corium). The epithelium is a very thin, inert pellicle, entirely composed of epithelial cells united by an almost insignificant quantity of amorphous matter (blastema). The cells are flat or polygonal, round or cylindrical, polyhedral, or very irregular in shape. In consequence of these diverse forms, there is pavement (or squamous), spherical (or spheroidal), and cylindrical or conical (or columnar) | ithelium. If the cells are furnished with small i appendages, named vibratile cilia, the — is then —— ciliated. When the are arranged in a single layer on the surface Gf the corium, the epithelium is said to besimple; "saz mourn, it is stratified when the cells are arranged in strata The large scale is magnified each other. In stratified epithelium, the 310 diameters, and exhibits pe of the cells is not the same on the surface % 2ucleus with nucleolus in _ beneath ~h and it is named after the form of suelo calla flewing tke superfici yer. body of the scale. ' ‘The mucous derm or corium corresponds to that 5 of the skin, as the epithelium corresponds to the epidermis. It is composed of connective (or areolar) tissue, whose thickness, elasticity, vascularity, and sensibility varies with the situation and the func- tion of organs. The corium is thin aud almost destitute of elastic fibres when applied to the bony walls of a cavity; on the contrary, it is thick, coxumNaR EPITHELIUM. ‘ elastic, and slightly adherent when it lines organs 1, Nucleus of the cell; 2, which, like the stomach, cesophagus, and intestines, meg ine ~ oe oe are capable of increasing or diminishing in capacity. ; ~ be esaang i < _ the Peauualieds tees 2% the oe rid seam yers e corium are loosely united, Fig. 145. but nearer the surface they lie eines some- ‘ times they form, under the epithelium, an surface-layer, the basement (or limitary) membrane. ‘lhe sub-epithelial face of the corium is scarcely ever smooth, but offers minute prolongationsnamed villosities or which are very varied in their form COLUMNAR CILIATED EPITHELIUM; and volume, and is more or less marked by MAGHIBIED S10 DIAMETERS. ions designated follicles. The villi % Nucleated cells resting on their are observed onthe deep-seated mucous mem- —— “™™'°* ®*tremities; °, Cilia. branes ; they are more particularly the vascular and absorbent organs. The papille are found towards the natural apertures, and are rich in nerves; they are more especially the organs of sensibility. The follicles, lined by one or other form of cell, are exclusively organs of secretion. b. The second membrane met with in the walls of the hollow organs is of & muscular, and sometimes of a cartilaginous nature. The muscular mem- brane is formed of unstriped fibres whose slow contraction is involuntary. Tn certain or, those adjoining the natural apertures—the unstriped fibres are rep by striped, which are under the influence of the will, or have the same physiological properties as the smovth fibres, as in the cesophagus, ~, Cad “y- 328 GENERAL CONSIDERATIONS ON THE DIGESTIVE APPARATUS. ( Unstriped or smooth bands of muscles are composed of long fusiform cells — ’ with staff-shaped, elongated nuclei, the cells varying from 1-1125th to 1-50th of an inch in length, and from 1-5625th to 1-1125th of an inch in breadth.) Fig. 146, CONICAL VILLI ON MUCOUS MEM- BRANE OF SMALL INTESTINE; MAGNIFIED 19 DIAMETERS. a, Zone of follicles surrounding a soli- tary gland; 6, Apertures of simple follicles, Fig. 147, S FUSIFORM CELIS OF SMOOTH MUSCULAR FIBRE, c. When the organs are lodged in one of the great splanchnic cavities, such as the chest or abdomen, they have a third mem- brane—a serous layer, which lines the cavity, and is reflected around the viscera contained in it, so as to envelop them more or less Oy) il. completely. This layer has, therefore, an adherent face, applied either against the walls of the cavity or the external surface of the splanchnic organs; and a free face always in contact with itself. A serous membrane is composed of two layers : a deep, connective portion, analo to the mucous corium ; and a superficial, whichis only pavement epithelium. The free surface of this epithelium is perfectly smooth, and lubricated by a limpid serosity to facilitate the gliding of the parts the membrane covers. (The epithelium is a simple tesselated layer of flattened and polygonal nucleated cells, about 1-1200th of an inch in diameter). 2. The solid organs are either contained in the splanchnic cavities or situated outside them, in the midst of connective tissue, which, in condensing around them, often forms a fibrous covering. Like the hollow organs, they are single— spleen, liver; or in pairs—kidneys ; and symmetrical or asymmetrical. They are retained in their situation by their vessels and nerves, by adherence to the neighbouring organs, or by particular serous attachments. With the exception of the lungs of animals that have respired, all the solid organs have a density greater than water. Their weight and volume offer numerous differences, which are individual or relating to the species to which they belong. Nevertheless, each organ pos- sesses a certain volume and weight which might be termed physiologic ; when the organ is above or below this average, we are authorized in saying that it is in a patho- logical condition. ans are more or less round in form, and their surface is traversed by a variable number of furrows which indicate their division into lobes or lobules. a, Two cells in their natural state, one showing the staff-shaped nucleus; 5, A cell with its nucleus, c, brought distinctly into view by acetic acid, : | GENERAL CONSIDERATIONS ON THE DIGESTIVE APPARATUS. 329 - Their colour is diverse; they may be very pale—parotid gland ; or very dark—liver, spleen; or uniform, or of different shades: varieties which are most frequently due to the mode of distribution of the vessels, or to the presence of certain anatomical elements. The colour of organs is not always the same in the deeper parts and at the surface, especially when they are enveloped by a thick, opaque membrane ; for instance, the testicle. Lastly, the coloration is less intense after death than during life, and particu- larly att the animal to which the organs belonged has been killed by effusion of bl The consistence of organs depends on their internal formation and the nature of their constituent elements; there are soft organs, such as the lungs, and resisting organs, as the testicles. Asa general rule, the consistence of organs diminishes after putrefaction has set in. Cohesion is the resistance that organs offer to the forces which tend to tear them ; it depends upon the texture of the organs, and the more or less abundance in their interior of fibrous and elastic tissue. Cohesion is very different from consistency ; thus, such an organ as the lung may be easily compressed, but may be very difficult to tear. If organs are examined with regard to their structure, it will be observed that all have a thin or thick fibrous casing which throws septa into their interior, and which support their proper tissue ; this tissue varies with the nature of the organs. It will also be found that they are traversed by a more or less considerable number of blood-vessels-—arteries and veins. These . vessels expand into a capillary network, whose meshes have a shape closely allied to that of the elements of the proper tissue. The number and volume of the vessels of an organ give an exact idea of its importance, and of the activity of the physiological phenomena taking place in it. Finally, into the composition of organs enter superficial and deep lymphatic vessels and nerves, which generally follow the arteries. The latter show in their course = ganglionic enlargements ; their mode of termination is most frequently own. Glands are organs of a particular construction, whose function it is to eliminate certain ag or solid products of the economy. The very peer (or tubular) glands consist of a straight or convoluted tube, or of a vesicular cavity opening on a tegumentary membrane, and are lined on their inner face by one or more layers of cells. As examples, there may be cited the tubular glands of the intestines and stomach, the racemose (or lobulated) glands of Briinner, and the solitary follicles of the intestine. ; _ _ But there are also conglomerate glands, organs more complex, though to the same groups as the simple glands. ‘These are glands com of tubes, like the kidneys and testicles ; racemose glands, such as the salivary glands and pancreas; a network of glands, like the liver ; or with closed follicles, such as the thyroid. In these the essential anatomical element—the polygonal, cylindrical, or spherical d-cell-—— is situated on the inner face of a tube, as in the kidney, or a demi-vesicle, as is seen in the pancreas, or deposited without any enlae in the meshes of a plexus of canaliculi, as occurs in the liver. The conglomerate glands aro provided with a common excretory canal, that commences in their mass by a great number of arborescent ramifications, The walls of this canal are composed of an elastic, and sometimes con- tractile, conjunctival membrane, covered on its inuer face by an epithelium, which may or may not be of the same character as that of the gland. 330 THE DIGESTIVE APPARATUS IN MAMMALIA, For a long time there have been classed as glands certain is—such — as the spleen and thymus body —without excretory ducts, and having only — remote analogies to glands. The function of these organs is but little known ; though as they are always abundantly supplied with blood-vessels, and as they are therefore believed to have connections with the vascular system, — they have been named vascular blood-glands. “red ; This is the limit to which the generalities relating to the viscera that _ form the object of splanchnology must be confined. We will now pass to the description of the digestive apparatus in mammals, and which consists, as mentioned above, of a series of enlarged cr tubuliform cavities, to which are annexed the glandular organs designated the liver, pancreas, and spleen. CHAPTER II. THE DIGESTIVE APPARATUS IN MAMMALIA. ” We will study, successively: 1, The preparatory organs, which include the mouth, the salivary glands annexed to that cavity, the pharyna, and — the wsophagus ; 2, The essential organs, comprising the stomach and intestine, and their annexes—the liver, pancreas, and spleen ; with the abdominal cavity, which contains and protects these organs. as Articte I.—Preparatory OrGANns oF THE Digestive APPARATUS. THE MOUTH. The mouth, the first vestibule of the alimentary canal, is a cavi situated between the two jaws, elongated in the direction of the larger axis of the head, and pierced by two openings: an anterior, for the introduction of food, and a posterior, by which the aliment passes into the pharynx. The mouth should be studied in six principal regions: 1, The lips, which circumscribe its anterior opening; 2, The cheeks, forming its lateral walls; 8, The palate, which constitutes its roof or superior wall; 4, The tongue, a muscular appendage, occupying its inferior wall; 5, The soft palate (velum pendulum palati), a membranous partition situated at the posterior extremity of the buccal cavity, which it separates from the pharynx, and concurs in the formation, by its inferior border, of the isthmus of the fauces, or posterior opening of the mouth; 6, The dental arches fixed on each jaw. We will study each of these regions in particular, before passing to the examination of the mouth in general. ; Preparation.—The whole of the mouth ought to be examined in an antero-posterior and vertical section of the head, as in figure 152. 1. The Lips. (Fig. 110.) These are two membranous movable folds, placed one above, the other below, the anterior opening of the mouth, which they circumscribe. There is, consequently, a SUPERIOR and an INFEKIOR Lip, united at each side by a commissure. Each lip offers for study an external and internal face, and a free and an adherent border. The external face is convex, and presents, on the median line: in the upper lip, a slight projection which divides it into two lateral lobes; in the 4 » THE MOUTH. 331 inferior lip, and altogether posteriorly, the single prominence named the tuft of the chin. This face, formed by the skin, is garnished with fine, short hairs, amongst which may be remarked long, coarse bristles, whose bulbs are implanted perpendicularly in the integument, and pass beyond its deep surface, to be lodged in the subjacent muscular tissue. These pilous tentacles ought to be considered as veritable tactile organs, as several sensitive nervous twigs penetrate to the bottom of their follicles. The internal face, constituted by the buccal mucous membrane, and moulded on the incisor teeth, is concave, smooth, rose-coloured, and often stained with black spots. In the superior lip, particularly, may be remarked humerous orifices opening on the summits of three small papille; these are the openings of the excretory canals by which the labial glands discharge their fluid into the interior of the mouth. The free border, thin and sharp, bears the line of demarcation, which - separates the two teguments. The adherent border is limited, in the buccal cavity, by a groove formed by the mucous membrane in its passage from the dental arches to the inner side of the lips. Beyond the mouth it is not indicated by any peculiarity of structure or arrangement, the skin being continued directly from the neighbouring parts on the lips. commissures mark, on each side, the point of reunion between the free border of the two lips. They are rounded in Solipeds, and offer nothing remarkable otherwise. Srrvorure.—Each lip is composed of two tegumentary layers: one cutaneous, the other mucous, between which is found muscular tissue and glands, and the general elements of every organisation—vessels and nerves. _ 1. Tegumentary layers.—The skin adheres closely to the subjacent tissues, and apart from the characters already indicated, there is nothing more to be said at present, with regard to its disposition, as it will be studied more completely with the organs of sense. With regard to the mucous membrane, it may be remarked that its derm is thick and dense, and lies on a layer of salivary glands; that it is provided with simple conical papille, and is covered by stratified pavement epithelium. (It is, sometimes streaked with pigment.) a Mescles. These are: the labial or orbicularis, the sphincter of the buceal aperture, and common to the two lips; in the upper lip, the aponeu- rotic expansion of the supermazillo-labialis, the musculo-fibrous tissue which separates this expansion from the cutaneous integument, and the terminal insertion of the supernasalis-labialis and the great supermazillo-. nasalis ; in the inferior lip, the tuft of the chin and its suspensory muscles— egtlgal intermediates (levatores menti). All these muscles having been ed in detail in the Myology (page 217), there is no necessity for their bein in described, 3. ial glandules.—These form an almost continuous layer between mucous membrane and the labial muscle. They are little secretory organs, similar in their structure and uses to the salivary glands, and will be described when these come under notice. 4. Vessels and nerves.—The blood is carried to the lips by the palato- labial, and the superior and inferior coronary arteries. It is returned to the heart by the satellite veins of the two last vessels. The lymphatics are very numerous, and pass to the glands between the branches of the lower jaw. The nerves are of two kinds: -the motor, which are given off from the facial nerve, and are distributed in the muscular tissue of the lips to cause its 332 THE DIGESTIVE APPARATUS IN MAMMALIA, contraction; the sensitive nerves, which are furnished by the maxillary branches of the fifth encephalic pair, are distinguished by their number and considerable volume, and are nearly all buried in the cutaneous integument, to which they communicate an exquisite sensibility. Founotions.—The lips serve for the prehension of solid and liquid food ; they retain it in the mouth after its introduction thereto, and likewise pre- vent the escape of the saliva, They ought also to be regarded, especially the upper lip, as very delicate organs of touch. 2. The Cheeks. (Fig. 110.) These are two membranous walls, which inclose the mouth laterally. In the interior of the buccal cavity they are limited: behind, by posterior pillars of the tongue; in front, by the lips, with which they are confounded around the commissures; above and below, by the groove formed by the gingival mucous membrane, where it is reflected from the molar sichis on to the cheeks. er The greatest diameter of the cheeks is antero-posterior, like that of the — cavity it incloses. Their vertical diameter is very narrow, especially behind ; in the anterior region, however, it can assume a certain amplitude by the separation of the jaws. Srrvcture.—The cheeks are formed by the buccal mucous membrane, external to which we find muscular tissue and glands. Vessels and nerves pass through these parts for the conveyance of nutritive fluids, sensibility, or the stimulus to contractility. 1. Mucous membrane.—The external face of this membrane is united in an intimate manner to the buccinator muscle, and to the inferior molar glands, Its free face presents, at the level of the third superior molar tooth, the buecal opening of the parotid duct, pierced at the summit of a variable- sized tubercle. On the face of each dental arcade there is also remarked a linear series of little salient points, analogous in their constitution to the large parotideal tubercle; these are the excretory orifices of the molar glands. Its structure is the same as the mucous membrane of the lips. (It is of a pale colour, and sometimes stained in patches with pigment.) 2. Muscular tissue-—This. is the buccinator or alveolo-labialis muscle already described. It may be remembered that the external face of this muscle is covered by the masseter, the superior molar glands, and the skin ; while the internal responds to the mucous membrane and the inferior molar glands. 3. Glands.—These are two masses of glandular lobules, known as the molar glands. They will be described with the salivary glands. Vessels and nerves.—The external maxillary, coronary, and buccal arteries carry blood to the cheeks. The veins empty themselves into the satellite branches of these arteries. The lymphatics proceed to the submaxillary glands. The nerves are of the same kind, and proceed from the same source, as those supplying the lips: being the seventh pair of encephalic or facial nerves for the muscular layer, and the fifth pair for the integuments (with filaments of the sympathetic for the circulation and the labial glandules). Funcotions.—The cheeks are very active agents in mastication, by con- stantly pushing the aliment, through the action of the buccinator, between the dental grinding surfaces. 3. The Palate. (Fig. 148.) Preparation.—Separate the head from the trunk; saw through the branches of the THE MOUTH. 333 maxilla above the angle of the jaw, and from the crown of the last molar tooth, so as to =e between the curtuin of the soft palate on the one part, and the base of the tongue on eé other, leaving the latter organ adherent to the lower jaw. This last should be removed from the upper jaw by cutting through the masseter and alveolo-labial muscles, and so exposing the hard and soft palates in such a manner as to render easy the special dissections necessary for their study. These dissections are limited to the removal of the mucous layer covering the deep venous network, and to the partial excision of this, which allows the artery an palatine nerves to be seen. (See figure 148.) The palate (hard palate), tine arch, or wu wall of the mouth, is circum- Grahel, in front and on the sides, by the superior dental arcade, and limited, behind, by the anterior border of the soft palate. It is a parabolic surface, exactly repre- senting, in its configuration, the bony palate (Fig. 21). On its face is remarked a median groove, which partitions it into two equal divisions, and which commences quite in front, at the base of a small tubercle. Curved transverse furrows, twenty in number (Leyh gives from sixteen to eighteen), divide each of these halves into an equal number of salient arches, whose concavities are turned backwards, and which become narrower and less marked as they are more posterior. (These arches and furrows aid in retain- ing the aliment which the tongue carries towards the palate during deglutition). Srrvorvure.—The palatine lies on the bony vault formed by the palatine and supermaxillary bones. It includes in its structure : 1, A fibrous membrane, applied to the bone just mentioned, which sustains a re- markably-developed venous network con- stituting a veritable erectile tissue, and Pin to the palate a greater or less egree of thickness, according to its state of turgescence (Fig. 148, 1). 2. A mucous layer,extremely adherent, by its deep face, to the preceding tissue, and of a whitish aspect in the horse. The corium, formed entirely of connective f ‘ , : 2 ; > }. - 7 | ‘ ‘A | “ if , 7 P mst my ie ; 4 ? . a3 4 ‘ itz | * , Ap fH Pe od } ” 4 db ve s: aay , ° ” J e rf. . . 3 ) y | ; s | . * * | 4 } p { ( r 4 ‘ ss i rn - 7 a i) a. 7 7 A az. \¢ ; i L del ~—- THE HARD AND SOFT PALATE, The mucous membrane has been removed from the right side, and, with the glandular layer, from the soft palate-— 1, The ridges of the palatine mucous membrane; 2, Venous network of the deep layer, which is cut through at the external side to show the palatine artery, 3, accompanied by the filaments of the palatine nerve; 4, Cartilaginous digitation, over which passes and is inflected the palatine artery; 5, Aponeurosis of the soft palate; 5’, Terminal extremity of the tendon of the external tensor palati, forming by its expansion the staphylin aponeurosis; 6, The palato-pharyageus ; 7, Circumflexus palati; 8, Staphylin nerves. 334 THE DIGESTIVE APPARATUS IN MAMMALIA, tissue, shows numerous conical papillw, especially at the posterior Pid of the palate. The epithelium fills up the de ions between the papille; it is stratified and squamous, and remarkable for the great thickness of its horny layer. 3. Two voluminous arteries —the palatine or palato-labials—lodged in the bony fissures of the palatine roof. ‘hese arteries proceed parallel to one another, and unite in front by anastomosing to form a single trunk, which enters the incisive foramen. It is of importance to know their disposition in a surgical point of view, as care ought to be taken not to wound them when abstracting blood from the palate. The blood carried by these arteries arrives in the deep-seated erectile membrane, and is finally removed by two very short venous trunks, which do not pass with the palato-labial arteries into the palatine canal, but only into the palatine fissure. 4, Sensory nerves which accompany the arteries, and are derived from the superior maxillary branch of the fifth pair of cranial nerves. Funotions.—The palate has a passive, but important, share in mastica- tion and deglutition ; furnishing the tongue, as it does, with a firm basis in the movements it executes when passing the food between the molar teeth, - and in carrying the alimentary mass backwards to the pharynx. \ 4. The Tongue. (Figs. 149, 152.) Preparation—1. By means of a strong saw without a back, make an antero-posterior and vertical section of the head, in order to study the general disposition of the ton 2. From another head remove the lower jaw, leaving the tongue in the in space, to examine the external conformation of the organ (see the dissection of the late). On a third head, kept for the study of the muscles, these parts are exposed in the following manner; The masseter is entirely removed, and the cheek is detached from the lower jaw and folded back on the upper jaw ; then the branch of the inferior maxilla is sawn through transversely, at first behind, next in front of the molar teeth: the upper piece of bone should be detached by luxating it behind the temporo-maxillary articulation, des- troying the capsular ligament and dividing the insertions of the pterygoid muscles. With regard to the inferior piece, it is reversed in such a way as to put the line of the molars — downwards, and the inferior border of the bone upwards in the bottom of the inter- maxillary space. ‘I'o do tliis it is sufficient to separate the buccal mucous membrane from the mylo-hyoideus muscle, proceeding from above to below. The dissection thus prepared, serves not only for the study of the muscles of the tongue, but also for those of the deep salivary glands, the pharynx, larynx, guttural pouches, the nerves and arteries of the head, ete. It is always better, in order to facilitate this dissection, io keep the jaws apart by fixing a piece of wood or bone between the incisor teeth immediately after the death of the animal. The lingual canal.—The inferior wall of the mouth (or floor), cireum- scribed by the lower alveolar arches, forms an elongated cavity named the lingual canal (or space), which lodges the organ designated the tongue. This canal occupies, in its anterior third, the superior face of the body of the lower maxilla, For the remainder of its extent, it is formed by a double groove, which is directed to the bottom of the mouth, at the sides of the tongue. It exhibits the sublingual crest and the barbs, of which we will s when describing the sublingual and maxillary glands. Situation of the tongue.—The tongue occupies the whole length of this elongated cavity, and thus extends from the back part of the mouth to the incisor teeth, lying in the intermaxillary space, where it rests on a species of wide sling formed by the union of the two mylo-hyoidean muscles, External conformation.—It is a fleshy organ, movable in the interior of the buccal cavity, and almost entirely enveloped by the mucous membrane which lines that cavity. In Solipeds, it forms a kind of triangular pyramid, a are” Fy THE MOUTH 835 from side to side, fixed to the os hyoides and the inferior maxilla by the muscles which form the basis of its structure, or by the tegumentary membrane which covers the organ. _ Its form permits it to be divided, for the study of its external disposition, into three faces, three borders, and two extremities. The superior face or dorsum of the tongue, narrower in front than behind, is roughened by numerous papille which give it a downy aspect. Two of these papille are remarkable for their enormous volume, their lobulated and the situation they occupy at the bottom of two excavations pico side by side, near the base of the organ; they are named the lingual e, or foramen cecum of Morgagni. This face responds to the palatine arch or roof, when the jaws are together. The lateral faces, wider in the middle of the tongue than at its extremities, are limited by the internal surfaces of the maxillary branches. Onthem are seen several large papille, and the orifices of some lingual glandule. These two faces are separated from the former by two /ateral borders, which correspond to the superior alveolar arches when the mouth is exactly elosed. With regard to the third or inferior border, its existence may be said to be fictitious; by it enter the muscles which constitute the substance of the tongue, and it is by it, also, that the organ is fixed at the bottom of the intermaxillary space. The posterior extremity, or base of the tongue, is limited, in the interior of the mouth, by a furrow which borders the base of the epiglottis. It presents a thick, median, mucous fold, plaited in different ways, and carried over the tr anterior aspect of the epiglottic cartilage. Two other folds, more anterior, moe . also formed by the buccal membrane, unite with the soft palate on each side the base of the tongue; these are the posterior pillars of the organ (or the glosso-epiglottic ligaments of Man), and comprise in their thick- ness a voluminous collection of glands. Behind these pillars are two triangular spaces, included between the velum pendulum palati and the base of the tongue, each of which has an excavation perforated with open- ings, a veritable amygdaloid cavity, which represents the amygdale (tonsils) of Man and the Carnivora; it is a kind of common confluent for the numerous glandulz accumulated outside the mucous membrane which lines this excavation. The anterior extremity of the tongue is quite independent from the middle of the interdental space, and moves freely in the interior of the buccal cayity: it is also termed the free portion of the tongue, in opposition to the remainder of the organ, which is named the fixed portion, This free portion is flattened above and below, and slightly widened or spatula Its superior face is plane, or nearly so, and prolongs that of the fixed portion.* The inferior, slightly convex, and perfectly smooth, is continuous with the lateral faces of the organ, and rests on the body of the maxillary bone; it is _ fixed to that bone by a median fold of mucous membrane, the anterior pillar, or freenum lingue. The borders, in joining each other in front, describe a _ parabolic curve which is in contact with the incisive arches. Sraveture.—The tongue offers for study, in regard to its structure : 1, The mucous membrane enveloping the organ; 2, The muscular tissue which, in reality, forms its mass; 3, The vessels and nerves distributed to it. 1. Mucous membrane.—This membrane, a continuation of that lining the mouth, is folded at the bottom of the canal on the sides of the tongue, covers the upper surface of the organ, and envelops the whole of its free portion. Its derm or corium has not the same thickness throughout, but is incom- 836 THE DIGESTIVE APPARATUS IN MAMMALIA. : parably thinner and less dense on the sides of the fixed portion and the inferior plane of the free part; on the dorsum of the tongue it is difficult to is cut it. Its deep face receives the insertion of a large number of the muscular fibres of the organ, and for the greater part of its extent it adheres in the most intimate manner to these fibres; though its adherence is not so close at those points where it is in contact with the labial glandules. Its superficial face is not smooth, but shows a prodigious quantity of minute prolongations or papille, which, according to their shape, are dis-— tinguished as filiform, fungiform, and calyciform papillae. The filiform papille are formed by thin prolongations terminating in a point, each being covered by an epithelial sheath which greatly increases its dimensions. They are simple or composite, having at their summit secondary prolongations, much smaller, and provided also with an epithelial covering. These filiform papillw are largest on the middle part of the dorsum of the tongue, where they present a tufty appearance; towards the point of the organ they are imbedded in epithelium, and are scarcely apparent in the minute elevations on its surface. . The fungiform papille (p. capitate) are club or sponge-shaped elevations of the derm, attached to the membrane by a short pedicle. Their surface is convex and smooth, or studded with filiform papille. They are scattered irregularly over the dorsum of the tongue, among the filiform papille, and are most numerous on the posterior third of its surface. The calyciform papille (fossulate, circumvallate, or lenticular papille) are really fungiform, but instead of projecting above the free surface of the derm, they are placed in a depression of this membrane. They are surrounded “by a slightly-elevated ring, within which is a narrow fossa around the pedicle of the papilla; several papille may be contained within one cup- shaped cavity. They only exist at the base of the tongue, where two of their number, very developed and composite, correspond to the blind holes of Morgagni (foramen cecum). At the base of a certain number of the fungi- form and calyciform papille is a band of adenoid tissue. It is generally believed that these three kinds of papille have each a distinct function; the filiform are to retain the alimentary and sapid sub- — stances on the surface of the tongue; the fungiform are tactile organs, and the calyciform are gustatory. 2. Muscles.—Beneath the mucous membrane, on the dorsal surface of the tongue, is a cylindrical fibrous cord which sometimes attains the thick- ness of a large goose-quill. This cord is situated in the median plane, near the middle part of the organ, and is from 2 to 8 inches long. It may _be considered as a fibrous support to the muscular tissue, and it sometimes directly adheres to the deep surface of the tegument. At other times, it is only connected with that membrane by a very short lamellar prolonga- tion, and is then buried a little deeper among the fibres of the superior muscular layer. (The German hippotomists designate this the cartilage of the tongue. Tt is only found in Solipeds, and was first described by Briithl, who gave it this designation. Leyh states that it is composed of dense fi i surrounded by cellular and adipose tissue; that it is from 4 to 7 inches long, and 3ths to 1 inch in thickness; and that it commences about an inch from the anterior appendix of the hyoid bone.) A similar cord, but not so strong or well defined, is sometimes found at the inferior surface of the free portion of the tongue. Intrinsic muscles.—In studying the proper substance of the tongue in ¥ ee ek ae 4 THE MOUTH, BRT two sections, one vertical and longitudinal, the other transverse, there is seen, under the dorsal mucous membrane, a layer of red fibres, very close in their texture, and very adherent to that membrane. Amongst these fibres, are some which affect a longitudinal direction, but the majority are vertical or transverse, and all are interlaced in the most intimate manner. It appears as if this layer (the lingualis superficialis of Man) was perfectly independent of the other muscular fibres, whose insertion it receives. It also forms a portion of those which writers have named the intrinsic muscles of the tongue, and which comprise a superior and inferior, a transverse and a vertical lingualis muscle. An attentive examination, however, readily shows that the fibres proper to this submucous layer are continuous with those which, coming from a point situated beyond the tongue, form the muscles named, in uence, extrinsic, and that they are only the prolongations of these. _ This division of the tongue into two orders of muscular fasciculi does not, for this reason, possess the importance generally accorded to it. Extrinsic muscles.—If the muscular fibres of the tongue appear to be one mass in the superior layer just referred to, it is not so when they are followed beyond this layer; on the contrary, we see them separate from one another, and even admit between them—at least in the fixed portion—a certain amount of adipose tissue, which is particularly abundant towards the base, where it forms a mass called the fatty nucleus of Baur; then they collect into fasciculi, or perfectly distinct muscles. __ In Solipeds, these muscles number five pairs; 1, The stylo- or Kérato- glossus ; 2, The great hyo- or basio-glossus ; 3, The genio-glossus; 4, The small hyo-glossus (the superior lingual of some authorities) ; 5, The pharyngo- glossus. STYLO-GLOSSUS. (Synonyms.—The hyo-glossus longus of Percivall. Kerato-glossus externus—Leyh. The stylo-glossus of Man.) This is a very long riband-shaped band, formed of bright-red parallel fibres, and extending from the styloid bone, or large branch of the os hyoides, _ to each side of the free extremity of the tongue. It originates on the external surface of the large hyoideal branch, near its inferior extremity, by a very thin aponeurosis ; and terminates near the tip of the tongue in expanding over the inferior surface and borders of the organ, and confounding its fibres with those of the opposite muscle. In the fixed portion of the tongue, this muscle responds: outwardly, to the mylo-hyoideus, sublingual gland, lingual nerve, and the Whartonian duct; inwardly, to the genio-glossus and great hyo-glossus muscles. The whole of its free portion is covered by the buccal membrane. In contracting, this muscle pulls the tongue towards the back of the mouth, and inclines it to one side when acting independently of its fellow on the opposite side (Fig. 149, 1.) ’ GREAT HYO-GLOSSUS or BASIO-GLOSSUS. (Synonyms.— Hyo-glossus brevis—Percivall. Hyo-glossus—Leyh.) A wide muscle, flattened on both sides, thicker than the preceding, and composed of fibres passing obliquely forward and upward, the longest of which are anterior. Its origin occupies the whole side of the body of the os hyoides, from the extromity of the cornu to that of the anterior appendix. Its fibres, after Z 338 THE DIGESTIVE APPARATUS IN MAMMALIA, becoming detached from this point of insertion, are insinuated beneath ae preceding muscle, spread out under the mucous membrane lateral aspect of the tongue, and for the most part are reflected inwards, cae to the superior face, to constitute the transverse fibres of the organ. It is in relation, outwardly, with the mylo-hyoideus, stylo-glossus, the — great hypo-glossal nerve, Wharton's duct, and the lingual mucous membrane; inwardly, with the small hyo-glossus, the small branch of the os hyoides, the — ¥ pharyngo-glossus, genio-glossus, lingual artery, the terminal divisions of the glosso-pharyngeal nerves, and great and small hypo-glossals. (Fig. 149, 2) It retracts the tongue in depressing its base, according as it acts singly or simultaneously with its fellow. (In 1850, Briihl described as the middle descending stylo-glossus, a long, narrow muscle arising from the lower extremity of the inner face of the styloid bone, or large branch of the os hyoides, and terminating near the — tip of the tongue, where it is covered by the hyo-glossus. It has since been — described as the internal or small Kérato-glossus. Its action is the same as the stylo-glossus. ) : ee GENIO-GLOSSUS. ~ pall (Synonym.— Genio-hyo-glossus—Percivall.) =" This is a beautiful muscle, whose fibres are disposed like a fan j in the vertical and median plane of the tongue. It originates from the inner surfaee of the lower jaw, near the symphysis, _ by a tendon parallel to that of the genio-hyoideus. From this tendon-are — detached a multitude of divergent fibres which pass backwards, upwards, and forwards, to reach the upper surface of the tongue and become continuous with the vertical fibres of the submucous layer. Fig. 149. MUSCLES OF THE TONGUE, SOFT PALATE, AND PHARYNX,. 1, Stylo-glossus; 2, Great hyo-glossus ; 3, The same, covered by the submucous — a layer formed by the expansion of the small ox glossus; 4, Genio-glossus; 5, a. Pharyngo-glossus; 6, Pterygo-pharyngeus; 7, yo-pharyngeus ; 8, Thyro-pha- =a ryngeus; 9, Crico-pharyngeus ; 10, (Esophagns ; 11, 12, Tensors palati; 13, Stylo-hyoideus ; 14, Hyoideus magnus; 15, Genio-hyoideus ; 16, Hyo-thyroideus ; 1%; Sterno-thyroidens ; 18, Crico-thy roideus. a THE MOUTH. an fibres are partly included between the two : layers of the frenum lingue. They are re- ‘) cr their external face, to the basio- or great a ossus, the stylo-glossus, ‘the sublingual gland, the r- el and the terminal branches of the three aS i feticn of the genio-glossus is complex; accord- j ing to the portion of its fibres which contract, it will _ ¢arry the tongue forwards, pull it into the buccal cavity, or draw it downwards into the floor of the mouth. SMALL HYO-GLOSSUS. oe superior of Man. (Lingualis of Perci- Under this name is described a thin band, formed of © parallel fibres, which is exposed immediately on remov- the mucous membrane, with the subjacent glands from the base of the tongue. This band arises from the inner side of the articulation uniting the body of the os hyoides to its small branch. It passes above the trans- verse muscle of that bone, which it crosses perpendi- eularly, is surrounded at this point by a great mass of tissue, and is prolonged directly forward, be- neath the lingual mucous membrane. Its fibres ‘then _ vanish, either on the superior aspect of the tongue or on its sides, or they descend obliquely in crossing the direction of the hyo-glossus, to joi the superior border of the stylo-glossus (Fig. 149, 3). (This muscle contracts and retracts the tongue.) PHARYNGO-GLOSSUS. _ (Synonym.— The palato-glossus of Man.) A rudimentary muscle formed of parallel fibres, _ which, from their origin on the lateral wall of the pass outside the articular angle of the branches of the os hyoides, and between the hyo-glossus and genio- i hare mixing with, and intercrossing their fibres. geo glands. —The numerous glands of the ma be divided into racemose Cr lobulated ) : oa oe - closed follicles (or follicular glands.) ____‘The racemose glands are spread on the sides and base ot the to Near its upper border they form two which are rendered visible. by the presence of a tubercle placed beside each of them. At the base 4 of the tongue they are found beneath the fungiform and ‘ oan papille, as well as beneath the layer of follicles which lines the isthmus of the fauces. At the entrance to this passage, the lingual mucous membrane is mammillated, and cach elevation has an LP fa 4 * (Pig. 149, 4.) . 339 The two genio-glossi lie together on the median plane of the tongue, ccept towards their origin, where they are constantly kept apart by adipose . Their inferior border responds to the genio-hyoid muscles, and their 4 ONE LOBE OF A RACE- MOSE GLAND. 2 1, Casing of connective tissue; 2, Execretory duct; 3, Glandular vesicle, or acini. Fig. 151. FOLLICULAR GLAND FROM THE ROOT OF THE TONGUE, 1, Epithelium; 2, Pa- pillw of mucous mem- brane; 3, Cavity of the follicle; 4, In- vesting coat of the gland composed of connective tissue; 5, Fibro- vascular ma- trix, forming its par- enchyma, and con- taining, 6, 6, the closed capsules or follicles. z2 B40 THE DIGESTIVE APPARATUS IN MAMMALTA, orifice. This arrangement is connected with the presence, at this part of — the tongue, of the closed follicles, which are more or less voluminous and aggregated, and separated from the muscles by a continuous layer of race- mose glands. They are composed of a casing of condensed connective,anda = mass of adenoid tissue, which has in its centre a cavity that communicates —__ with the orifice above the follicle, and is lined by the lingual epithelium __ minus its horny layer. : 4. Vessels and nerves.—The tongue is supplied with blood by two arteries, the lingual and sublingual; the blood is removed by three large __ veins, two of which enter the external maxillary, and the third the internal maxillary vein. The lymphatics constitute a very fine superficial network, whose emergent branches pass to the submaxillary glands. The nerves are the lingual, the glosso-pharyngeal, and the great hypo-glossal; the latter is a motor nerve, and consequently supplies the muscles; the others are exclusively sensitive, and are distributed more particularly to the mucous membrane. 5. aie Funcrions.—The tongue serves for the prehension of liquids in all animals, and for solid aliment in the Ox. It concurs, with the jaws, in pro- pelling the substances to be crushed between the molar teeth during masti- cation ; and it is, besides, one of the essential organs of deglutition. If is able to play this important and complex part through the varied movements it can execute in the interior of the mouth; and the extent of these move- ments demands a moment’s notice. ‘They are of two kinds: those which influence only the form of the organ, and those which cause it to submit to various displacements, They result in either compressing it from side to side, above to below, or curving it longitudinally, and even transversely. These movements are principally, but not exclusively, due to the action of the intrinsic fibres ; they are perfectly independent of the movements which, as a whole, produce the total displacement of the tongue. With regard to these latter, they may result in carrying the tongue beyond the mouth, or withdrawing it into that cavity, inclining it to one side, raising it against the palate, depressing it on the floor of the intermaxillary space or, finally, lifting it towards the pharynx. It is worthy of remark that these move- ments do not alone result from the action of the proper lingual muscles above described ; those belonging to the os hyoides, to which is attached — the lingual appendix, concur also in producing them. But this appendix is not the only organ thus attached to the hyoidea! apparatus ; the larynx and, through its intermediation. the pharynx, are placed in the same conditions, and are obliged to follow, like the tongue, the movements of the bony frame- work supporting them. There consequently results between these three organs a remarkable unity of action, which is readily explained by the part they all take in the one common act of deglutition. . 5. Soft Palate. (Figs. 148, 152.) Preparation.—The soft palate is studied: 1, On the antero-posterior and vertical section of the head (fig. 152); 2, On the portion intended to show the interior of the pharynx (see the preparation of this region); 3, On the portion represented in fig. 148, the mode of dissecting which has been indicated at page 333; in removing the mucous membrane and glandular layer, the fibrous membrane and the two intrinsic muscles are exposed, The extrinsic muscles should be studied with those of the pharynx. Situalion—Form —The soft palate (palatum molle, velum pendulum palati) is suspended like a partition between the mouth and the pharynx, and by its THE MOUTH. 3t1 ior border circumscribes the orifice which establishes a communica- tion between these two cavities. This partition, which continues the palate posteriorly, represents in its external form a membranous valve, oblique from above to below and before to behind, much longer than it is wide, and exhibiting for study two faces and four borders. The inferior or anterior face, turned towards the mouth, shows longi- tudinal folds and transverse ridges, with multitudes of orifices belonging to the submucous glandule. On its sides it is united to the base of the tongue by means of two thick mucous columns, designated the posterior pillars of the tongue. The superior or posterior face constitutes the anterior wall of the pharynx ; it only exhibits some very slight longitudinal ridges. Fig. 152. MEDIAN LONGITUDINAL SECTION OF THE HEAD AND UPPER PART OF NECK. 1, Upper lip; 2, Premaxilla; 3, Hard palate; 4, Tongue; 5, Septum nasi; 6, Nasal bone; 7, Palatine arch; 9, Pterygoid bone; 10, Epiglottis; 11, Entrance to the Eustachian tube; 12, Arytenoid cartilage; 13, Cricoid cartilage; 14, Esophagus ; 15, Frontal bone and sinus; 16, Cerebrum; 17, Corpus callosum ; 18, Cerebellum ; 19, Sphenoid bone; 20, Medulla oblongata; 21, Cervical ligament ; 22, Spinal cord ; 23, Occipital bone ; 24, 24, Atlas; 25, 25, Dentata; 26, Trachea. The two lateral borders arc inserted into the walls of the two cavities which the soft palate separates. The anterior border, continuous with the late, is attached to the palatine arch, and follows the curve described by it. The posterior border, the only free one, has a concave form, and closely embraces the base of the epiglottis, which is most usually found reversed on the pcsterior surface of this curtain. This border is continued at its extremites by two thin prolongations, which can be followed on the lateral walls of the pharynx to the csophageal infundibulum, above which they unite in the form of an arch. These prolongments are named the ior pillars of the soft palate, in contradistinction to the two mucous folds at the base of the tongue, which constitute, by their relation to this partition, veritable anterior pillars. This posterior border concurs to cir- 342 THE DIGESTIVE APPARATUS IN MAMMALIA, cumscribe what is named the isthmua of the fauces, an aperture constantly — closed, in consequence of the great development of the soft palate; itis only — dilated for the passage of the alimentary substances passing into the pharynx. The isthmus of the fauces is, therefore, not merely an opening; it is a — passage which has for its inferior wall the base of the tongue as far as the — epiglottis ; for its upper wall the anterior face of the soft palate; and for its sides the posterior pillars of the latter. Srructurr.—To give the most simple idea of the structure of the soft palate, it might be said that the mucous membrane of the palate and that of the floor of the nasal cavities are prolonged behind the palatine arch, parallel to one another, and become joined towards the free border of this curtain; and it might be further shown that, in the space between these two mucous ‘membranes, there is a fibrous membrane, muscles, a glandular layer, vessels, and nerves; besides these, there are no other elements in the organi- sation of the soft palate. They may be studied in the following order: 1, Fibrous membrane ; 2, Muscles; 3, Mucous membranes ; 4, Vessels and nerves. 1. Fibrous membrane (Fig. 148, 5).—This membrane, remarkable for its — power of resistance, formsa real framework for the soft palate, of which it only ~ occupies the anterior moiety. It is attached in front of the palatine arch, and is prolonged posteriorly by a particular muscle, the palato-pharyngeus. 2. Musclzs.—Of these muscles, which are all pairs, there are those which — constitute a layer situated in the middle of the soft palate itself, and representing the intrinsic muscles ; these are the pharyngo-staphyleus (palato- pharyngeus) and the palato-staphyleus (circumfleaus palati), The others, the peristaphyleus,—external and internal (tensors palati, external and internal), are only inserted into the organ by their terminal extremities, and therefore act as extrinsic muscles, PHARYNGO-STAPHYLEUS. (Fig. 148, 6). (Synonym.—Palato-pharyngeus.—Pereivall.) In removing the mucous and glandular layers which cover the anterior face of the soft palate, there is exposed a wide and thin muscular fasciculus succeeding the fibrous layer behind, and occupying the posterior half of the __ entire organ. The fibres of which this muscle is composed, confounded on __ the median line with those of the muscle on the opposite side, are directed backwards and outwards, the most posterior followimg the curve of the free border of the curtain. Arriving near the lateral border, they are re- flected upwards, passing between the pharyngeal mucous membrane and the middle constrictor of the pharynx, with which it appears to be con- founded posteriorly ; but with a little attention it can be followed to the superior border of the thyroid cartilage, into which it is inserted after making a somewhat long track under the mucous membrane of the pharynx, This muscle stretches the curtain, and draws its free border from the cesophageal infundibulum during pharyngeal deglutition. PALATO-STAPHYLEUS. Ue ; t (Synonyms.—Staphyleus—Girard, Circumflexus palati—Percivall. The azygos woulee J vas of Man.) ran A small, elongated, cylindrical, bright-red muscle, in opposition, on the median line, to that of the other side, and extending over the inferior surface of the pr eceding, from the palatine arch to the free border of the soft palate, which it pulls forward and upward to dilate the isthmus of the fauces. Tt >. THE MOUTH. $43 ae by a small glistening tendon, not from the palatine, but from the vular aponeurosis (Fig. 148, 7), The fascia which the two muscles form is for the most part covered, in its middle portion, by the fibres of the tensores palati. - fi PERISTAPHYLEUS EXTERNUS. (Synonyms.—Tensor palati—Percivall. The circwmflexus of Man.) This is a small, elongated muscle, depressed on both sides, bulging in its middle, thin and tendinous at its extremities, and extending obliquely for- ward and downward from the styloid process of the temporal bone, where _ it has its origin, to the pterygoid trochlea. Its terminal tendon glides and is inflected inwards on this pulley, to be afterwards spread ont and confounded with the fibrous framework of the soft palate, which causes this framework to represent an expansion of the tendon. The muscle is covered outwardly by the pterygoidei muscles; it responds, internally, to the next muscle, which separates it from the Eustachian tube. It is a tensor and depressor of the aponeurosis of the soft palate (Fig. 149, 11). PERISTAPHYLEUS INTERNUS. (Synonyms.—Stylo-pharyngeus—Perciyall. The levator palati of Man.) This is formed by a pale and thin band, which originates with the ing muscle, descends between it and the Eustachian tube, passes the superior constrictor of the pharynx, then below the mucous membrane of the pharynx to reach the soft palate, where it expands on the anterior or posterior surface of the palato-pharyngeus, beneath the glandular layer, its fibres becoming mixed, on the median line, with those of its fellow. This is an elevator of the soft palate (Fig. 149, 12). 3. Glandular layer.—This layer is comprised between the fibrous membrane and the anterior mucous layer, becoming thinner as it is pro- over the intrinsic muscles; it does not extend to the free border of the organ. It is thickest on each side of the median plane, where it forms two lobes which appear on the anterior aspect of the soft palate as an elongated ridge, much more marked in the Ass than the Horse. It is worthy of notice, that the glandular granulations composing this layer throw all their secre- tion into the mouth—that is, on the anterior face of the septum. 4. Mucous membranes.—The soft palate is covered on both its surfaces by two mucous layers, one anterior, the other posterior, united, as has been remarked, at the free border of the organ. The anterior is continuous, above, with the mucous membrane of the hard palate; on its sides, with that which covers the base of the tongue. In structure it is the same as the buccal membrane; its epithelium is stratified pavement. The other layer is nothing more than the pituitary membrane extended over the posterior surface of the septum, and thence to the lateral surfaces of the pharynx. It will be more fully described with the latter. 5. Vessels and nerves —The soft palate is supplied with blood by the ascending pharyngeal and internal maxillary arteries. The nervous filaments this partition receives emanate from the fifth pair of cranial nerves (superior maxillary branch), and from Meckel’s ganglion; they form the posterior palatine nerve (Fig. 148, 8). Functions.—During the act of deglutition, the soft palate is raised to S44 THE DIGESTIVE APPARATUS IN MAMMALIA, enlarge the isthmus and allow solids or liquids to pass through, The deserip- tion given of this septum permits us to understand how it plays the , valve in rising freely while the alimentary bolus or mouthful of flui never allows the matters which have once entered the cesophageal canal return into the buccal cavity. Also why, when any obstacle is opposed to ‘i descent of aliment into the esophagus, after it has cleared the isthmus of the fauces, or even when the animal vomits, the matters arrested in their passage or expelled from the stomach are ejected by the nasal cavities, after flowing over the posterior surface of the soft palate. This dispoaaas phe of the pendulous curtain, in forming a complete partition which hermeti- cally seals the orifice of communication between the mouth and pharynx, likewise sufficiently explains why, in normal circumstances, Solipeds respire exclusively by the nostrils. 6. The Teeth. Passive agents in mastication, the teeth are hard organs, bony in appearance, implanted in the jaws, and projecting into the interior of the mouth to bruise or lacerate the solid alimentary substances. Identical in all our domesticated animals, by their general disposition, — their mode of development, and their structure, in their external con- formation these organs present notable differences, the study of which offers the greatest interest to the naturalist. For it is on the form of its teeth that an animal depends for its mode of alimentation; it is the régime, in its turn, which dominates the instincts, and commands the diverse modifiea- tions in the apparatus of the economy; and there results from this law of harmony so striking a correlation between the arrangement of the teeth and the conformation of the other organs, that an anatomist may truly say, “Give me the tooth of an animal, and I will tell you its habits and structure.” Compelled by the limits of our task to confine ourselves to the purely descriptive part of the dental apparatus, we cannot stop to notice the interesting physiological considerations on which this principle is founded ; but will begin at once the anatomical study of the teeth by indicating their general characters, before examining them successively in all the domestie- ated species. A. GeyxeraL CHARACTERS oF THE TrETH—GeENERAL Disposition.—The teeth are fixed in the jaws, and ranged one against the other in such a wa as to form two parabolic arches opening behind, and interrupted on cathe side by what is called the interdental space. Distinguished into superior and inferior, like the jaws to which they belong, these arches come in contact _ ans another in a more or less exact manner when the mouth is perfectly closed, Those teeth which are placed altogether in front, at the middle of the dental arches, are named incisors or incisive teeth ; the others, situated behind these, and always numbering two for each jaw, are called the canine teeth or tusks ; while the designation of molars is given to those which occupy, in the more retired portion of the buccal cavity, the lateral parts and extremities of the dental arches. Exrernat Conrormation.—Each tooth represents, when completely developed, an elongated polyhedron, which has sometimes a pyramidal form, and at others that of a cone or a parallelopiped. | THE MOUTH. 345 - A portion of the tooth is buried and solidly implanted in one of the or veolar cavities of the maxillary bones; this is the root or imbedded portion, (or fang). The other portion, circumscribed at its base by the gum, leaves the alveolus to project into the interior of the mouth, forming the crown or free portion, The narrow constriction between the crown and root is named The fang is perforated at its inferior extremity by one or more excavations _ (cavitas pulpe) which penetrate deeply into the substance of the tooth, and admit into their interior the vasculo-nervous papilla, simple or ramified, known by the name of the bulb or dental pulp. _ The crown, the portidn submitted to friction during mastication and, consequently, to wear, offers the most varied forms: sometimes it is shaped _ like a very acute cone; at others, it is divided into several tubercles more _ or less salient; and sometimes, again, it carries at the extremity of the tooth _ & wearing surface more or less plane and regular. Srrvoture.—Three essentially different substances enter into the structure of all the teeth: the ivory; enamel, and cement ; to which ought to be added the soft parts, the pulp, gum, and alveolo-dental periosteum. lyory.—The ivory, or dentine, has the hardness of bone, is of a whitish- yellow colour, and is rendered brilliant in places by its nacrous reflection. It forms the principal mass of the tooth, enveloping everywhere the pulp cavity. Examined by aid of the microscope, this substance is found to be channeled by a multitude of minute, undulating, and branching canals (dental tubuli) imbedded in amorphous matter—the fundamental substance. uP Fig. 153. -_ ‘~~ > eer por er _f om Jy / SECTION THROUGH THE FANG OF A MOLAR TOOTH, a, a, Dentine traversed by its tubuli; 4, , Interglobular, or nodular layer ; ec, c, Cementum, The tubuli, or canaliculi, extend from the dental cavity to the inner face of the enamel ; single at their origin. they soon bifurcate, and again anasto- ‘mose several times atta their slightly-undulating course. They terminate in a cul-de-sac, or in irregular cavities situated beneath the enamel, and named the interglobular spaces of Czermak (forming the interglobular or nodular layer). These canals have a thin proper wall, and contain a dental fibre, which very probably is a continuation of the pulp-cells. The _ fundamental substance (or matrix) is amorphous, and not very abundant; in B46 THE DIGESTIVE APPARATUS IN MAMMALIA. lawl ited the saline molecules which give the dentine its on consistency. (These molecules are deposited in lamelle, L the pulp En Nasmyth considers the fibres to be rows of minute ¢ paque- points arranged in a linear series (baccated fibres), and to be r f nuclei of the ivory cells, the interfibrous substance being the the cell filled with calcareous matter.) Its chemical composition much resembles that of bones. After reme in dilute hydrochloric acid for several weeks, it comports itself like the giving up the calcareous salts with which it is impregnated to the : solution, and becoming soft like cartilage ; submitted to the action of boiling water it yields gelatine. es Enamev.—The enamel extends in a layer over the bony substance of the free portion of the tooth, whose exterior it entirely envelops; it is prolonged over the fang in some animals, and in several kinds of teeth it Pee ' ; crown into the interior of the organ to a very great depth. It is bri white, and so hard that it strikes fire like steel. ] Its microscopic structure is very interesting, the enamel | being composed = of small prismatic hexagonal rods, 1-5000th of an inch in diameter, and — notched on their faces. Owing to this notching, the prisms are intimately united to each other. They form several layers which cross each other at Fig, 154, * , "pulp (x); this organ, destined for the secretion of the {pening by which dentine, then fills nearly the whole of the follicle. — perves communicate In its upper part is observed the enamel organ, or germ with the pulp; 6, 6, (enamel membrane), formed by a prolongation of the Peed showing gingival epithelium, and connected with the latter by a 2°04, Structure; “ a Pe 1; 8, 8, mass of cells named the gubernaculum dentis. daa Te c y there is, o ite the bottom of the follicle, one or more papille which, in some cases, adhere by their whole length to one of the lateral walls of the follicular sac, and the free _ extremities of which cross those of the dentine papillw, or are buried in 348 THE DIGESTIVE APPARATUS IN MAMMALIA, a kind of cup hollowed on the summit of the latter appendages (c). are covered by the membrane of cylindrical cells mentioned above (D). With regard to the enamel organ, its internal face also presents a hyer i. of cylindrical cells. It is in the interval between these two papillary systems, that the dental ’ substance is deposited as ina mould, consequent on a process of secretion and transformation, the mechanism and progress of which are somewhat complicated. The dentine is produced by the metamorphosis of the —— = ficial cells of the dental germ. These cells send out ramifying prolonga which constitute the tubuli of the dentine, and those of the middle layer secrete an intertubular amorphous substance in which the earthy salts are deposited from without inwards. The enamel is deposited on the dentine, — and results from the transformation of the cylindrical Bige 2 00- cells of the germ into enamel prisms. The cement is, : in its turn, deposited either on the enamel or the dentine after their formation, and is produced, like dontal) sac, which has become alveolar periosteum. This development will be alluded to in the chapter on the foetus. When formed by the process above indicated, the tooth pierces its follicle and appears in the interior of maxillary bones, if there is any, and the gingival membrane. (When the calcification of the different Sat tissues of the tooth is sufficiently advanced to enable THEORETICAL SECTION OF it to bear the pressure to which it will be afterwards THE DENTAL SAC OF A subjected, its eruption takes place, the tooth making — tan noe. its way through the gum. The gum is absorbed by THE HORSE, : the pressure of the crown of the tooth against it, A, Proper membrane of the sac; B, Dental pulp; c, Which is itself pressed up by the increasing size of Papilla of the external the fang. Concurrent with this, the septa between cavity (pit) of the tooth, the dental sacs, at first fibrous in structure, soon ossify, 4 prion wed of the ii, 8nd constitute the alveoli; these firmly embrace the thelial layer of ‘he de,, necks of the teeth, and afford them a solid basis of tine membrane; B, Cy- Support — Gray.) Though it has so far become esta-— lindrical cells of the blished in its functions, the process of growth in the enamel membrane; F, tooth has not yet ceased. The pulp lodged in the Dentine; Gr enamel. internal dental cavity, and charged with the formation The secretion of the ce- ment is not supposed to Of the ivory or dentine, continues its functions: inces- have commenced. santly depositing new layers on those which were originally secreted. ‘The dental cavity gradually diminishes in extent; the papilla becomes atrophied, and finishes by disap- pearing altogether at a period of life more or less advanced, according to the kind of teeth and species of the animal. In considering the entire dental apparatus, with regard to its develop- ment, very interesting differences are remarked in the progress and period of evolution ; differences which have been made available for ascertaining the age of animals, but the details of which would be out of place here, It may only be noted, that all animals have two successive dentitions: the first, composed of a certain number of teeth designated the caducous (tem- porary, deciduous, or milk-teeth—caduques, decaying or frail), because they are soon shed and give place to others which are stronger and more solid the bony tissue, by the internal face of this (perio- 2 the mouth, after having traversed the table of the THE MOOTH. Pap 319 (and also because they appear while the animal is yet sucking); the second, comprising the latter, are named replacing teeth (remplagantes), with new, non-deciduous teeth which are not replaced, and are therefore named a teeth. (The replacing and persistent teeth are generally included yy us in the term permanent.) _ B. Teern or Sonpeps—tThe dentition of adult Solipeds is composed of from 36 to 40 teeth, thus distributed in each jaw: male, 6 incisors, 2 canines, 12 molars; female, 6 incisors, 12 molars. With regard to the first dentition, it comprises the incisors and three anterior molars only, the canine teeth and the three posterior molars being persistent. The latter teeth—those of the second dentition—offer in their develop- ment a common, but very remarkable character, rarely met with in the other animals. They are thrust up from the alveoli during the entire life of the animal, to replace the surfaces worn off by friction ; so that the crown is formed successively by the various portions of the fang, each of which issues in its turn from the alveolar cavity. . Iyctsors.—These are so named because they serve, particularly in the Fig. 157. b THIN SECTION OF THE INNER PORTION OF THE DENTINE AND OF THE SURFACE OF THE PULP OF AN INCISOR TOOTH. a, Portion in which calcification is complete, showing separate globular masses at the line of junction with the uncalcified substance, b; at ¢ are seen oval masses of germinal matter (cells), with formed material on their outer surface; d, Terminal portions of nerve fibres. Herbivora, for the incision (incido, to cut) of the food. They are arranged in the segment of a circle, at the extremity of the jaw, and are distinguished by the names of pincer, intermediate or lateral (mitoyennes), and corner teeth. The pincers are the two middle teeth, the intermediates the next, and the corners occupy the extremities of the incisive semicircle. The general form of these teeth is that of a trifacial pyramid, presenting an incurvation whose, concavity is towards the mouth. The base of this pyramid, formed by the crown, is flattened before and behind; the summit, or extremitySof the fang, is, on the contrary, depressed on both sides; the shaft of the pyramid offers, at different points of its height, a series of intermediate conformations which are utilised as characteristics of age, the continual pushing outwards of the teeth bringing each of them in succession to the frictional surface of the crown (Fig. 159, 1). Examined in a young tooth which has completed its evolution, the free portion exhibits: an anterior face, indented by a slight longitudinal groove, which is prolonged to the root; a posterior face, rounded from side to side; 350 THE DIGESTIVE APPARATUS IN MAMMALIA. ce a two borders, of which the internal is always thicker than the external; lastly, the surface of friction (table). The latter does not exist in the tooth _ which has not been used; but in its stead is found two sharp margins circumscribing a cavity named the external dental cavity (or bétter, in- fundibulum). This cavity terminates by a conical cul-de-sac, which descends more or less deeply into the sub- Fig. 158. stance of the tooth. The margins are dis- tinguished into anterior and posterior; the __ last, less elevated than the first,iseut byon or more notches which are always deepestin __ the corner teeth. ~It is by the wear of these margins that the surface of friction is formed, _ and in the centre of which the infundibulum __ persists during a certain period of time (Fig. 159, 2). 3 . The fang is perforated by a single aper- — ture, through which the pulp of the tooth — penetrates into the internal cavity (Fig. 159, 3, ¢). ; = In be composition of the incisor teeth is found the three fundamental substances of — the dental organ. The dentine (Fig. 159, 3,b) envelops, as has been shown, the pulp cavity, That which is deposited in this cavity after the complete evolution of the tooth, to replace the atrophied pulp, has always a yellower tint than the dentine of the first forma- — tion ; it forms on the table of the tooth the — mark designated by Girard the dental star (Fig. 159, 4, ¢). The enamel covers the dentine, not only on its free portion, but also on the roots of the incisors; it is not prolonged, however, to their extremities. It is doubled into the external dental cavity, lining it throughout (Fig. 159, 3, a); and — when the surface of friction is established, there can be perceived a ring of enamel surrounding that surface, and an internal ring _ circumscribing the infundibulum: the first circle forms what is called the encircling enamel ; the second, the central enamel (Fig. 159, 4, a, b). In the virgin tooth, the latter is con- tinuous with the external enamel, and passes THE DENTITION OF THE INFERIOR oye» the border which circumscribes the JAW OF THE HORSE, THE TEETH to sien Ok erie< eee entrance to the infundibulum. The cement Consult figure 21 for the dentition of 18 applied Over the enamel like a protecting the upper jaw. varnish ; but it does not exhibit the same thickness everywhere: on the salient portions @g it is extremely thin, and does not even exist when the tooth has been J submitted for some time to the friction arising from the contact of the aliment, the lips, and the tongue. It is more abundant in depressed situations, as in the longitudinal groove on the anterior face, and particularly THE MOUTH. 351 the bottom of the infundibulum. Nevertheless, the quantity accumulated this cul-de-sac is not always the same; we have seen it sometimes almost and on the other hand we possess incisors unworn, or nearly so, in which the cavity is almost entirely obstructed by the crusta petrosa. We _ are not aware that, up to the present time, any account has been taken of _ these differences when calculating the progress of wear; but it may be _ imagined that they ought to influence in a sensible manner the period at __ which effacement of the external dental cavity takes place. z Fig. 159. INCISOR TEETH OF THE HORSE. DETAILS OF STRUCTURE. 1, A tooth in which is indicated the general shape of a permanent incisor, and the cular forms successively assumed by the dental table in consequence of friction, and the continued pushing outwards of these teeth; 2, A virgin tooth, anterior and posterior faces; 3, Longitudinal section of a virgin tooth, intended to show the internal conformation and structure. Not to complicate the figure, the external cement, and that amassed in the infundibulum, has not been exhibited. 4, Transverse section for the same purpose; a, Encircling enamel ; b, Central enamel; c, Dental star; d, Dentine; 5, Deciduous tooth. SYR erry. x , r Peyriy, All the characteristics just indicated belong to the deciduous teeth (Fig. 159, 5), except that they are smaller than the permanent; that they are of a shining milky-white colour, due to the thinness or absence of the erusta petrosa; that they show at the point of union between the free portion and the root, a constriction named the neck ; that their crown is finely striated, and not cannular, on the anterior face ; that the external cul-de-sac 352 THE DIGESTIVE APPARATUS IN MAMMALIA, (infundibulum) is shallow; and that they are not constantly pushed out- wards from their cavities, their growth ceasing when they begin to be used. When the replacing teeth appear, they do so a little behind the temnpord ones, whose shedding they cause by gradually destroying their roots, w . at last become only a long and very thin shell of dentine. 7" The follicle in which the incisor teeth are developed shows only two Ney papillw ; one for the secretion of the dentine, lodged in the internal eavity — of the tooth, and hollowed into a cup-shape at its free extremity; the other — is contained in the external cul-de-sac (Fig. 156, A. B. ©). Tusks, Fanas, or Canine Teeru.'—‘ The tusks of Solipeds only exist in the male; it being quite exceptional to meet with them in the female, and even then they are rarely so strong as in the male. . “These teeth are four in number, and are placed one at each side of the jaws, a little behind the incisors, to which the lower canines are much — nearer than the upper. Between them and the first molar there is left a considerable space, which constitutes the bar of the inferior jaw. “The free portion of the tusk, slightly curved and thrown outwards, — particularly in the lower jaw, offers two faces: an external and an intertial, separated from one another by two sharp borders inclined to the inner side, and meeting in a point at the extremity of the tooth. The external face, a rounded, presents a series of fine stria, longitudinal and parallel. he internal face has a conical eminence in its middle, whose point is directed towards that of the tooth, and is separated from each border — by a deep groove. “The fang of the tusk, more curved than the free portion, bears internally a cavity analogous to that of the root of the incisors, and like it, this diminishes and finally disappears as it advances in age; but it” is always relatively larger, because of the absence of the infundibulum in — the canine teeth. “The form we have described for the tusks is that which they present while still young. As the Horse grows older they lose their whiteness, and become worn in an irregular manner, and this most frequently by the action of the bit or snaffle; for the difference in position of these. teeth in the two jaws does not allow of friction between them, “The canine teeth are not shed, and grow but once, Some veterinarians, and among them Forthomme and Rigot, have witnessed instances in which they were replaced ; but the very rare exceptions cannot make us look upon ~ these teeth as liable to be renewed. We must not, however, confound with these exceptional cases the shedding of a small spicula or point, which, in the majority of Horses, precedes the eruption of the real tusks.” “The structure of these teeth is much simpler than that of the incisors ; consisting, as they do, of a central mass of dentine hollowed by the pulp cavity, and covered by an external layer of enamel, on which is Jevouited a little cement. “The disposition of the developing follicle is in harmony with the simplicity of structure of the tusks; at the bottom there is a simple and conical papilla for the internal cavity ; on the inner wall, a double longi- tudinal ridge, on which are moulded the ridge and grooves on the internal face of the tooth.” ; Moar Treru.—* The molars are twenty-four in number—six in each side of each jaw. There are also sometimes supplementary molars met with ' The quotations included within inverted commas are from M. L —_ s ‘Traité de VExtericur du Cheval et des Principaux Animaux Domestiques.’ THE MOUTH. 853 _in front of the true ones, and which may be four in number; but these are small teeth, having but little resemblance to the others, are most frequently shed with the first deciduous molar, and are not replaced. * Generally considered, the molar arcades have not the same disposition in both jaws. Wider apart in the superior one, they form « slight curve, whose convexity is outwards. In the inferior jaw, on the contrary, the two ‘arcades separate in the form of a V towards the back of the mouth. Instead of coming in contact by level surfaces, the molars meet by inclined planes, and in such a way that the internal border is higher than the external in the inferior molars, while the opposite takes place in the superior, “Like the incisors, each molar presents for study a free and a fixed on. ** The free portion, nearly square in the upper molars, longer than wide in the lower, shows at the external surface of the former two longitudinal grooves, the anterior of which is the deepest, and which are continued on the encased portion. This is not the case with the inferior molars, which have but one narrow, and frequently an indistinct, groove. Fig. 160. PROFILE OF THE UPPER TEETH OF THE HORSE, MORE ESPECIALLY INTENDED TO SHOW THE MOLARS; THE FANGS HAVE BEEN EXPOSED. a, Molar teeth; 6, Supplementary molar; c, Tusk; d, Incisors. “The internal face in both jaws only shows one groove, and that but little marked ; it is placed backwards in the upper molars, and is most apparent towards the root. “The anterior and posterior faces are in contact with the corresponding faces of the adjoining molars, except at the extremities of the arcades, where the isolated face is converted into a narrow border. “With regard to the table of the tooth, it inclines, as we have already mentioned, outwards in the lower jaw. and inwards in the upper; a circum- _ stance which prevents the lateral movements of the jaws taking place with- out separation of the incisors, which separation removes them from friction.” In the virgin molar this face is completely covered with enamel, and irregularly undulated. In it may be recognised the entrance to the two infundibular openings, which are prolonged in the interior of the organ to the extremity of the root, and whieh are almost entirely filled with cement at the period when the tooth has completed its evolution; they are only vacant before the secretion of this crusta petrosa. In the tooth which has 2A 354 THE DIGESTIVE APPARATUS IN MAMMALIA, been worn, this frictional surface assumes a particular aspect, which will indicated with most advantage to the student by examining the structure o the molar. “The root, if examined a short time after the eruption of the er = portion, looks only like the shaft of the latter, without any appear- ance of fangs, and has internally a wide cavity. It is not until the tooth begins to be pushed from the alveolus and its crown to become worn, that its fangs are formed; these are at first hollow, and afterwards filled, as well as the cavity of the tooth, by the formation of a new quantity of ‘dentine. ; “ei From this time the fangs cease to grow; but the tooth, constantly } beyond the alveolar cavity, allows the walls which inclose it to contract ; so that, in extreme old age, it happens that the shaft, completely worn aay, instead of the tooth, leaves several stumps formed by the “The molars of the two jaws exhibit a variety of roots. In the molars — terminating the arcades, either above or below, or at the extremities of these, there are three; while the intermediate molars have four fangs in the be jaw, and only two in the lower. “The molars are separated from each other by their imbedded portion, particularly at the two extremities of the arcade; an arrangement which ap strengthens them by throwing the strain put upon the terminal teeth towards the middle of the line.” The structure of the molars resembles that of the incisors, though it is much more complicated. The internal cavity is extremely diverticulated, and enveloped by the dentine. The enamel is applied in a layer over it, andis doubled in its external culs-de-sac exactly as in the incisors. There is also © on the table of the tooth which has been worn, an external covering of enamel, and two circles, or rather two irregular polygons, of central enamel circumscribing the two cavities. In the superior molars, these bands of enamel represent a Gothic B, having a small appendix on the loop nearest the entrance to the mouth. This figure is modified in the teeth of the lower jaw, the enamel of the infundibuli being continuous, on the inner side, with the external enamel. The cement is extremely abundant, and in the upper molars its total quantity nearly equals that of the “dentine ; ; accumulates in the culs-de-sac and on the external covering of enamel, where it partially fills up the flutings on the faces of the crown. Prolonged | steeping of a molar tooth in hydrochlorie acid easily permits the isolation of these elements. Owing to the arrangement above described, the section of an adult molar tooth, naturally re sented by the surface of friction (Fig. 161), exhibits, outwardly, a layer of cement; next, the external enamel; between this and the central enamel, the dentine, always yellower, and sometimes even black in the middle; lastly, the enamel Fig. 161. TRANSVERSE SECTION OF A ee bands of the infundibuli, and the crusta petrosa HORSE'S UPPER MOLAR ’ . TOOTH. filling them. As these enamel bands are much A, External cement; Bb, Ex- harder than the other substances, they are worn — an c ar more slowly and stand out in relief on them. trnal arusts neteos, ‘Lhe table of the tooth has also, for this reason, the petrosa, ; : : : appearance of a veritable mill-stone, and is admi-— rably disposed for the trituration of those fibrous substances on which the animal usually feeds. tans ee Sy TH 8p THE MOUTH. 355 The follicle which develops these three elements of the molar tooth, offers at the bottom an enormous papilla divided into several lobes, which lie together for their whole length ; lodged in the internal dental cavity, it gradually decreases, like the papilla in the other kinds of teeth, as the cavity becomes diminished by the formation of new dentine. Opposite to , _ it are two long papille, which occupy the enamelled infundibuli, _ “It was believed for a long time that the molars of Solipeds were all istent teeth. This error, founded on the authority of Aristotle, was so Aeply rote that although Ruini, towards the end of the sixteenth century, iscovered the existence of two temporary molars, Bourgelat did not believe it when he founded the French Veterinary Schools, and was only eon- vineed when Tenon had proved by specimens, in 1770, that the first three of each arcade are deciduous, “The replacement of these twelve molars is not at all like what happens with the incisors. The molar of the adult grows immediately beneath the tem- porary one, and divides its two fangs into four, until its body is reduced toa simple plate and falls off, allowing the contracted summit of the permanent to appear ; and this grows up until it is soon on a level with the others in the row. “The first replacing molar is always a little more elongated than that which it succeeds, and it most frequently expels at the same time the sup- tary molar; so that if forty-four teeth be developed in the male it is very rare that they are all present at the same time.” 7. The Mouth in General. We will now consider, as a whole, the cavity whose various parts have been studied in detail, and examine, successively, its general disposition, capacity, and mucous membrane. General disposition and capacity of the mouth—The mouth being elon- gated in the direction of the head, offers a great antero-posterior diameter, aud two small diameters—one vertical, the other transverse. The first extends from the base of the epiglottis to the anterior opening of the mouth ; the second, from the palate to the floor of the mouth; and the third, from one jaw to the other. When the jaws are in contact, the space included between these limits is divided into two regions: one central, the other peripheral. The first is circumscribed by the dental arches; the second is comprised between these arches on the one side, and the cheeks and inner aspect of the lips on the other. It may, therefore, be remarked, that the capacity of the mouth is almost null in these regions. The cheeks and lips, in reality, lie almost exactly against the alveolar arches, and the tongue, in contact with the palate by its superior surface, almost entirely fills the central region. If the jaws separate from one another, and the cheeks recede from the dental arcades, the cavity of the mouth becomes enlarged in proportion as these movements are extensive. It must be remembered that the separation of the jaws is effected in an angular manner, and that the dilatation produced in the mouth by this movement is greater before than behind, the opening of the angle comprised between the two jaws being directed tow the entrance of the cavity. Mucous membrane.—The walls of oper ar popes are Byte by a tegumentary membrane, which we have hitherto only examined in parts in the diferent regions it covers, but which, it is to be noted, forms here a single and continuous layer, the mucous membrane of the mouth. This membrane is continuous with the external skit at the margin of the 2a2 356 THE DIGESTIVE APPARATUS IN MAMMALIA, buccal opening ; followed from this point into the interior of the cavity it lines, it is seen to spread itself at first over the internal surface of the lips, — then to be prolonged backwards on the cheeks as far as the posterior pillars of the tongue. If it is examined above and below, to the bottom of the groove which corresponds to the point of insertion of the lips and cheeks, it is seen to cover the maxillary bones ‘and envelop the base of the teeth, where it constitutes the gums. From the superior dental arcade, it extends — over the palatine arch and the soft palate. And from the inferior areade, — it descends to the floor of the mouth, and is reflected over the tongue to form — a covering for that organ. At the isthmus of the fauces it is continuous with the pharyngeal mucous membrane. The organisation of the mucous membrane of the mouth is nici in harmony with the digestive acts performed in that cavity. It is where the alimentary substances, which are sometimes very hard, very resisting, and covered with asperities, are crushed ; and to escape inevitable injury, this membrane is protected by a very thick epidermis in those places which are most particularly exposed to the contact of these substances, such as the upper surface of the tongue, the palate, and the cheeks; even the corium or sub-epidermic layer, is also greatly thickened. But nature has — not made this provision for the parts which are removed from the direct contact of alimentary matters; as, for example, on the lateral aspects of the tongue, where the buccal membrane is delicately organised. : This membrane also shows, in its lingual portion, small organs for the gustation of savours, the perception of which is one of the most important preparatory acts of the digestive functions; as the sensation resulting from this appreciation constitutes an excitant to the desire for food, and also informs the animal of the good or bad properties of the substance introduced into the mouth. a DIFFERENTIAL CHARACTERS IN THE MOUTH OF OTHER THAN SOLIPED ANIMALS. That the different regions of the mouth in the domesticated animals should offer some diversities will be readily conceived, as all are not submitted to the same régime, nor do they all live in the same manner. Rumrnants. 1, Lips.—The lips of the Oz are remarkably thick and rigid, and possessed of but little mobility, notwithstanding the great development of the muscles that move them; so that they only concur indirectly in the prehension of food, the tongue being charged with the largest share in this important task. The upper lip offers in the middle of its external surface a large patch destitute of hair, variousl coloured in different animals, always humid in health, covered by small*de eminences, and perforated by minute apertures, through which the secretion of numerous thick, yellow, subeutaneous glandules passes to the surface. This space, situated between the two nostrils, constitutes the muffle. (Around the muffle are a few hairs sometimes, Of the nature of tentacule.) In the Sheep and Goat the lips are thin and very mobile, and take an active part in the prehension of food. The upper lip does not show any muffle, and is divided into two portions by a median groove. In the Sheep this grvove is in reality a fissure; so that each half of the lip can be readily moved independently of the other. (The w lip is covered with hair in both animals. The Goat has a long tuft of hair appended to its lower lip, the beard.) 2. Cheeks.—On the inner surface of the cheeks in the Ox, Sheep, and Goat, from the commissure of the lips to the first molar tooth, is a multitude of long, thick, conical papille directed backwards. Beyond, there are only small round elevations and a single row of large papille similar to the preceding, in a line with the upper molars, In the Sheep the mucous membrane is sometimes spotted black. 3. Palute—In the Oz, the palate is most extensive. Its posterior third is quite smooth, and the transverse ridges (bars) only occupy the anterior two-thirds. (They are usually sixteen in number.) They are not curved, but are cut into notches on their summit, which is inclined backwards. In the Sheep and Goat, as also in the Oz, is THE MOUTH, 357 in front and in the middle, near the pad that replaces the upper incisor teeth, a kind of T, the stem of which is directed forwards, and at the extremity of whose branches is a very narrow aperture, the buccal opening of Jacobson’s canal. This will be deseribed with the nasal cavities. _ 4. Tongue.—The tongue of the Oz is distinguished by the enormous development of the muscles composing it, It is garnished with conical papillae which have a horn sheath, and whose summits, inclining backwards, give the tongue a very rough feel. Tn this animal it serves for the prehension of food; its mobility is very great, and it can be carried into the nostrils with ease. (The body of the organ is rounder, and the point finer than in the Horse. The calicyform papille are spread over the whole of its dorsal surface ; and at the root, on the middle line, is a somewhat deep groove.) The tongue of the Sheep and Gout is smaller, proportionally, than that of Solipeds. 5. Soft Palate—It may be said, in a general manner, that the palatine prolongment is shorter than in Solipeds. (The isthmus of the fauces is wider, however, and the amygdala, very developed, are situated in the two large depressions formed on the sides of the soft palate by the folding of the mucous mem- brane. ) 6. Teeth —The teeth of the Oz are thirty-two in number, twenty-four of which are molars, arranged as in the Horse, and eight incisors belonging to the lower jaw. The latter are re- eee weet py by 5 by cartilaginous pad, covered the mucous membrane of the mouth ; this pad forms the gum, and furnishes a bearing for the incisors of the lower jaw. Some- i as in the Horse, there are fi supplementary molars, which, if four in number, will make up the whole to thirty-six ; they are never all present at one time, as the supplementary ones are shed before the molar dentition is completed, The composition of the Ox’s teeth is the same us those of the Horse, the only difference bein in the arrangement of the severa Incrwsors. — “The incisors, eight in number, are placed en elavier (like a key-board) at the extremity of the kind of rounded shoulder-bone by which the max- illary bone terminates, forming around this point a perfect circle when they have acquired their THE TEETH OF THE OX. full development. 1, Upper jaw, with a, the friction surface, and }, the “Tustead of being fixed in external surface; 2, Lower jaw, with a, the dental the alveoli, as in Solipeds, they tables, and, }, the external face. a certain degree of mo- , Sometimes mistaken for a diseased condition; this is necessary in order’ to prevent their wounding the cartilaginous pad of the upper jaw agninst which they press. They are divided, according to their position, into two pincers, two first inter- mediates, two second intermediates, and two corner incisors. “Each incisor offers for consideration two parts: one free, the other encased, con- 858 THE DIGESTIVE, APPARATUS IN MAMMALIA. stituting the root, and separated from one another by a marked constriction—the « neck. thie seamen gives to the tooth the form of Hip! foe the root representing — the handle (fig. ). ; “The free portion, flattened above and below, and thinnest and widest towards its “| anterior extremity, presents two faces—an inferior or external, the other superior or a internal; with three borders, an anterior and two lateral. } ie “The external face, slightly convex, and milk-white in colour, is covered with fine, _ Fig. 163. undulating, longitudinal strie, which disappear = with age, and leave the surface = polished (fig. 163, a). ee “The internal face, flatter than the pre- ceding, presents in its middle a slight coment: terminated . eminence, whose base widens and is near the free extremity of the tooth, while its sides are cireumscribed towards each border by a well-defined groove (fig. 163, a’). “The two lateral borders (the internal — slightly convex in its length, the external — slightly concave in the same direction) make — the free portion’ appear as if thrown outward = The anterior border is sharp, and slightly con- vex from one side to the other; it is the first part of the tooth destroyed by wear. “The root is round slightly conical, and implanted in an alveolus of the same form; in youth, it shows at its extremity an opening OX’S INCISOR TOOTH. er se an eee cavity bap a, Free rtion, external face, outer aia lg hme Bie 2; ipeds, and pro- border Pak Ibid, internal face, outer dei b. the interior of the free portion beet . pp sist f, Anterior © '"« In the virgin tooth, the enamel forms around 309 : the free portion a continuous layer, thinnest on the internal surface, and extending very scantily over a part of the root. “The dentine composes the remainder of the organ, and the (pulp) cavity, which is originally a large space of the same form as the tooth, is filled, as the animal Fakt old, by new dentine, which, as in the Horse, hasa yellower tint than the primitive ivory. “ When the cavity is completely filled, the tooth ceases to grow, and is not pushed beyond the alveolus during wear, like the teeth of the Horse. “The incisor tooth has scarcely arrived at its perfect development before it begins to be worn. Its horizontal position, and its coming in contact with the pad on the upper jaw, exposes the anterior border and superior tace to friction, and consequent wear from before to behind. The wear, therefore, chiefly affects this upper face, which really _ forms the table of the tooth, and which Girard designated the avale. When use has worn away the conical eminence and the grooves bordering it, the tooth is levelled. ; “ As wear goes on, there appears at first, and at the extremity of the tooth, a be band, which is the dentine denuded of its enamel; and later, in this ivory a yel transverse band shows itself. With increase of wear, this contracts, then widens, and finishes by forming a mark nearly square, and then round, which is nothing else than the recently-formed dentine that fills the pulp cavity of the tooth. It is a veritable dental star, analogous to that in the Horse’s tooth, and varying in form according to the incisor in which it appears. “In proportion as the teeth are used, they seem to separate from one another, although they still remain in the same places. ‘This is becuusre these teeth, in youth, ouly touched each other by their extremities, and as they became worn they decreased in width, and necessarily became separated to an extent varying with their degree of wear. _ “ Finally, when the tooth has reached its last stage of wear, there only remains the © rout, the upper portion of which, becoming apparent by the retreat of the gum, stands as a yellow stump, very distant from those which form with it the remains of the incisive arcade. “ The first incisors (or milk-teeth) of the Ox, like those of the Horse, are all deciduous, and differ from those which replace them by their smaller volume, less width, the transparency of their enamel, and their being more curved outwards. Their roots are much shorter, and. sare destroyed by the succeeding teeth. ‘Che two temporary pincers . are always separated by a marked interval, depending on the thickness of the fibro- cartilage in the maxillary symphysis during youth.” by THE MOUTH. 359 Mo.ars.—* As in Solipeds, the molars are six in each side of the jaws, but they are much smaller, and form a much shorter arcade. Their reciprocal volume is far from ~ __ being as uniform as in the Horse, but goes on augmenting from the first to the sixth; and ft dege a degree, that the space occupied by the three anterior molars is only about one- _* of that required for the three posterior ones; the last molar alone occupies nearly four times as much space, lengthwise, as the first. “Their wearing surface, constructed on the same system as that of the Horse’s molars, ___ presents eminences a little more acute.” —_ ‘The arrangement of their three constituents is in principle the same as in the latter ¥ _ -, _ * As in the Horse, the three front molars are deciduous. “The teeth of the Sheep and Goat are, like those of the Ox, thirty-two in number, divided into eight incisors and twenty-four molars, to which are sometimes added tary molars. * The incisors of the smaller Ruminants are not disposed like a key-board, as in the Ox, but stand up to form a grip, resting against the pad on the upper jaw much more by their extremity than by their inner surface. “They are, besides, narrow, have scarcely any neck, and are fixed more solidly in the alveoli (fig. 164). “Their external face is white and polished, and is encased towards the gum ina kind of black cement. “The internal face has two wide, longitudinal grooves, separated towards the middle of the table by a simple ridge, which replaces the conical eminence of tlie Ox’s incisor. These grooves are nearly #tways lined with the black cement-like substance. “The incisors of the Sheep are, like the Ox’s, distinguished into temporary and replacing teeth; the first are known from the others by : their smallness, and particularly by their narrowness. Fig. 164, “The wear of the incisors in the Sheep, from their As — ought to take place nearer the anterior border in the Ox; the dental star is observed more mptly, and always forms a narrower line from before to “The absence of a neck in these teeth is the reason why never ae to separate with wear, as has been Xx. in the “The molars have the greatest resemblance, in their rNcisoR TEETH OF A SHEEP general form and relative proportions, to those of the Ox.” TWO YEARS OLD. Pig.—“1. Lips—In this animal the lips are widely The second intermediates and cleft. The lower is pointed and little rise ; the upper the corner incisors have not is confounded with the snout, which will be described yet been replaced. with the nostrils.” (The upper lip has but little mobility.) “2. Cheeks.—These are small and thin, and the mucous membrane smooth, _ @avity they show on their table, some analogy to those of the Horse. In the lower = these teeth are straight, directed forwards, and bear some resemblance to the of rodent animals. The corner incisors of both jaws are isolated between the intermediate and canine teeth, and are not nearly so yoluminous as the other incisors, “The tusks are very developed, particularly in the male, and cross each other during the life of the animal; they project from the mouth, and form a very dangerous weapon in the wild boar. The primary canines are deciduous like the incisors. “The molars, seven in each row, increase in volume from the first to the last, which is very strong. Their tables hold a middle place, with regard to disposition, between that of the Carnivora and Herbivora. ; “Canxivoua.—1. Lips.—The Carnivora, like the Pig, do not use their lips to grasp oo 360 THE DIGESTIVE APPARATUS IN MAMMALIA, their food, and they are therefore thin, though movable. The upper lip of the Dog has” a groove in the middle line, and it covers the lower lip more or less at the sides according to the breed, The lower lip is always scalloped on its free border near the — commissures, which are very high. In the Cat, the hairy tentacule are collected on th» upper lip into two long lateral tufts, the moustaches; they are very sensitive and movable. “2. Cheeks.—3. Palate—The cheeks resemble those of the Pig; the palate that of = the palate.” (The latter is frequently quite black. The number of ridges varies seven to nine. Jacobson’s canal opens behind the incisors.) “4, Tongue.—This is thin and very movable. The papille on its upper face vary somewhat in the Cat and Vog. In the former, the filiform papille on the anterior two- Ruminants. The mucous membrane is often stained by patches of pigment, capcolell Fig. 165. . ¥ THE TEETH OF THE PIG, f R 1, Upper teeth, table surface ; 2, Lower teeth, table aspect; 3, Lateral view of the jaws. thirds of the tongue are covered by a very strong horny sheath, whose point is directed backwards, In the J/og these papille are less developed, and there are observed, more — particularly, a number of composite filiform p»pille whose divisions are very flexible. There also are found regularly disposed among these, white shining epithelial particles which correspond to the fungiform papillae. “ At the ba:e of the tongue of Carnivora, and within the anterior pillars of the soft palate, are two elongated bodies with rounded extremities and a bosselated slippery surface; these are veritable amygdalz, formed by an agglomeration of closed follicles. “5. Soft Palate..-In the Dog and Cat, the soft palate is very short, and the isthmus of the fauces wide. Consequently, these creatures breathe easily by the mouth, and expel matters by it from the stomach during vomiting. At its free border the soft palate shows a small prolongat on, something like the uvula, THE MOUTH. : 361 _ “6. Teeth—The teeth of the Dog are forty-two in number: twelve incisors, four canines, and twenty-six molars, “The incisors, six in each side of the jaws, are more developed in the superior than . in the inferior maxilla, and are divided, as in the Horse, into pincers, intermediates, and corner incisors; the last being much stronger than the preceding, and these again ia, than the pincers. _ Their free part presents, in the virgin tooth, three tubercles: a middle, which is the strongest, and two lateral; these, together, are not unlike a trefoil or the upper part of a fleur-de-lis, especially those in the upper jaw. On the internal face is remarked a table or slope, somewhat resembling that of the Ox and Sheep, and separated from the root by a very distinct border whose extremities mark the lateral lobes. This table is of no vantage in ascertaining the age. “The root, very developed, flattened on both sides, and separated from the free ef Fig. 166. GENERAL AND LATERAL VIEW OF THE DOG’S TEETH. em by a well-defined neck, is solidly encased in a deep alveolus. Its internal cavity ene Bahar | obliterated. <5 the tooth is submitted to wear, the middle lobe is the first to disappear; so that it no longer resembles a trefoil (fig. 167. “The caducous incisors are much smaller and more pointed than the permanent ones; yet, like them, they show lateral lobes. At the period of their eruption these teeth are somewhat widely apart. “The fangs, or canine teeth, two in each Fig. 167. alg are very strong, sen 993 organs, conical form, curved backwards and outwards, and immediately after the incisors. “The upper fangs are the thickest, and havea small s between them and the corner incisors, in which the inferior canines are lodged. . * These teeth are deciduous, like the incisors, and are distinguished from the replacing ones _____ by their being thinner and more elongated. ‘J “They are worn more or less quickly, ac- cording to the kind of food the animal obtains, and are sometimes broken in fighting. “The molars are distributed in the two ANTERIOR VIEW OF THE INCISORS AND jaws, twelve being fixed in the upper and four- CANINE TEETH IN A YEAR-OLD DOG, 3 teen in the lower. Nearly all of them are 3 terminated by somewhat acute lobes, proper for tearing animal food. The strongest fF, in each jaw is, for the upper, the first back-molar or fourth in the row, and in the lower, the fifth. All in front of these are deciduous.” 362 THE DIGESTIVE APPARATUS IN MAMMALIA, After their complete eruption from the alveolar cavities, the Dog’s teeth are no longer — pushed outwards, They are remarkable for their brilliant whiteness, which they owe’ to the absence of cement on their covering of enamel. The Cat has thirty teeth: twelve incisors, four tusks, and fourteen molars, eight of which are in the upper, and six in the lower jaw, All these teeth are constructed on tle same type as those of the Dog. The tusks are deeply striated on their external surlace, instead of being smooth. (The ane rr: of a correct knowledge of the period of eruption, shedding, replacing, and general wear of the teeth of the domesticated animals, as a guide to their age, . induces me to give the table on \ page 363 (from Leyh), as indicating at a glance the age at which the teeth appear, are shed, and replaced in the different creatures: Baumeister divides the successive evolutions in the wear of the tables of the Horse’s incisor teeth into four periods—from six years to extreme old age. The first, the trans- versely-oval period, extends from six to twelve years: the round, from twelve to eighteen years; the triangular, from eighteen to twenty-four years, and the antero- posterior oval or triangular, from twenty-four years and upwards. Girard and other French authorities shorten these periods somewhat. The triangular period, for instance, only lasts from fourteen to seventeen years.) COMPARISON OF THE MOUTH OF MAN WITH THAT OF ANIMALS. The brevity of Man’s face influences the shape of the mouth; therefore it is propor- i tionally shorter and wider than in the domesticated mam:nals. Fig. 168. MEDIAN ANTERO-POSTERIOR SECTION OF THE HUMAN FACE. a, Septum of nose, with section of hard palate below it; b, Tongue; c, Section of soft palate; d, d, Lips; u, Uvala; r, Anterior arch, or pillar of fauces ; i, Pos- terior arch; t, Tonsil; p, Pharynx; A, Hyoid bone; 4, Thyroid cartilage ; n, Cricoid cartilage ; s, Epiglottis; », Glottis; 1, Posterior opening of nares; 3, Isthmus faucium ; 4, Superior opening of larynx; 5, Passage into esophagus; 6, Orifice of right Eustachian tube, r ae eS ee a wt THE MOUTH. 08 we) + ae 98 * soyumeg eT * ®, 7 — “HITAL AO YAANON . . syquout $9 03 $c . . . . savok g . . . . . . Wweaag : syyUOUL g 03 ¢ < wh *savok z 03 FT * savok ¢ 04% Sas * siwok ¢ 04% *wxIg . 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Lips.—The lips have a thick, free, everted border. They are lined by a rosy — mucous membrane, which is insensibly continned inwards by the buecal membrane. The upper lip is limited by the nose and the naso-labial furrow; the lower is er the mento-labial groove, The first has in its middle the subnasal furrow. structure is analogous to those of animals. 2. Cheeks.—The cheeks are limited by the inferior border of the maxilla, the root of the ear, the prominence of the chin, and the naso-labial furrow. Between the skin the mucous membrane, there is found, as in brutes, a glandular layer and muscles, chiefly the buccinator. An adipose ball is always found near the anterior border of the masseter. 3. Palate.—It does not possess a vascular membrane, as in the Horse, and its mucous membrane shows a longitudinal and transverse furrows in its anterior two-thirds. It is pale and resisting. 4. Tongue.—This is thick, short, and broad; its base is almost vertical, and in the middle is a perpendicular, fibrous, and semilunar Jamina, the lingual septum which gives insertion to muscular fibres. ; Anthropotomists. distinguish intrinsic and extrinsic muscles. The first are: the lingualis superior and inferior, transversus, and longitudinalis. The second are, as in Solipeds, the stylo-glossus, genio-glossus, hyo-glossus, and pharyngo-glossus. ‘There is also described a palato-glossus, which partly belongs to the solt te. <=] The mucous membrane shows the different characters recognised in that of animals. That of the dorsal face is divided into two portions by two A-shaped rows of papilla, whose summit abuts on the deep mucous follicle named the foramen cxcum. The Rerpeal portion presents depressions which correspond to the closed follicles, and the ungiform and calyciform papillae; the anterior portion has a villous aspect, due to the great number of filiform papille: covering it. 5. Soft Palate—In Man, the soft palate is short and divided into two portions: an anterior, horizontal, attached to the of the tongue by the anterior pillars of the curtain; a posterior, movable and oblique, liaving a free portion, the uvula, and fixed to the lateral walls of the pharynx by the posterior pillars. The amygdal#, or mass of closed follicles, are lodged in the triangular space between the anterior and posterior pillars. The fibrous structure is not present, unless the small expansion of the external tensorof the palate represents it. The muscles are the same as in ani and, in addition, there are descri two palato-glossal muscles, included between tle mucous folds that form the anterior pillars. The palato-pharyngeus extends to the posterior nasal spine. The isthmus of the fauces is wider than in the Carnivora. 6. Teeth—The teeth are thirty-two in number, sixteen in each jaw. They are distributed in the following manner: four incisors, two canines, two small molars (bicuspidati), and three large molars (multi-cuspidati). The incisors, when viewed in profile or longitudinal section, have a wedge-shape, and their free border is more or less sharp. The canines are irregularly conical; the molars have a multiple fang, and the crown is studded with a variable number of tubercles: two on soe small molar and four on the large. In youth, there are only twenty teeth, ten in each jaw. ef THE SALIVARY GLANDS. The salivary glands are secretory organs annexed to the buccal cavity, into which they pour saliva: a recrementitious fluid that softens the food, favours its mastication and deglutition, and has a chemical action upon it after its arrival in the abdominal portion of the digestive canal. Though very diversified in form, yet they present in their structure such common characters, that, to obviate a recurrence to their organisation when speaking of each gland, we will describe it here. The salivary glands are constituted by a red or yellow spongy tissue, which is divided into small, rounded, or polyhedral masses, called salivary lobules. These extend in a layer beneath the adherent face of the mucous membrane, and remain isolated from each other, or are agglomerated in a body to form a single gland. In the latter case they are united by condensed connective tissue, which is disposed over the surface of the organ as a very thin enveloping membrane, and into the lobular interstices in lamellar prolongations. res THE SALIVARY GLANDS, 365 Tn studying the organisation of one of these lobules, it will be observed that it is made up of many very small secondary lobules or acini, which are themselves due to the agglomeration of minute elementary vesicles or follicles, whose average diameter is from 1-500th to 1-1200th of an inch; these open into the little canal belonging to each of the secondary lobules, and which again joins those of the other acini of the primary lobule, to form a single duct. The minute elementary vesicles or follicles, the glandular culs-de-sac (or ultimate follicles) consist of a thin amorphous membrane (membrana propria), lined by a layer of polygonal epithelium cells. (They are closely sur- rounded by a plexus of capillary blood-vessels). When the salivary lobules remain isolated, this canal, which is designated as excretory, because it carries from the lobule the saliva secreted within the elementary follicles, opens directly into the mouth. But when, on the contrary, they all unite and form a single gland, their excretory canals finally converge into one or more principal ducts, whose termination in every case takes place in the same manner—by opening into the mouth from the summit of a more or less salient tubercle, an arrangement which Fig. 169. Fig. 170. LOBULE OF PAROTID GLAND, INJECTED WITH CAPILLARY NETWORK AROUND THE FOLLI- MERCURY, AND MAGNIFIED 50 DIAMETERS. CLES OF THE PAROTID GLAND, renders the introduction of particles of food into these excretory orifices somewhat difficult. The fibrous and elastic walls of these ducts are lined internally by columnar epithelium. If to the fundamental tissue just described, be added arteries, veins, and lymphatics, which convey the materials of secretion and nutrition, as well as the nerves which regulate the secretory and nutritive acts, all the elements entering intv the organisation of the salivary glands are made known. The most voluminous of these glands—or those which comprise a very great number of agglomerated lobules, will be first noticed. They are the parotid, mazillary, sublingual, and molar glands, which are all pairs, and are placed in proximity to the mouth when they do not lie immediately beneath the adherent face of its mucous membrane. Secondly, the less im- portant glands—those which are spread in layers under that membrane, and including the labial, lingual, and palatine glands, will be examined, 1, Parotid Gland. (Figs. 110; 172, 8). Preparation —This gland, with its excretory canal, is seen after the removal of the cervico-facial subcutaneous and parotido-auricularis muscles, The parotid gland is situated in the space included between the posterior 366 THE DIGESTIVE APPARATUS IN MAMMALIA, border of the inferior maxilla and the transverse process of the atlas. Ttis = elongated from above to below, flattened on both sides, and divided into — two faces, two borders, and two extremities. ; The external face, nearly plane, is hollowed in its inferior part into a — longitudinal channel, which is sometimes transformed into a complete canal, and lodges the jugular vein after it has traversed the gland from below to its superficies. This external face responds to the parotido-auricularis muscle, the subcutaneous muscle, the atloidean loop, a cervical ramification of the facial nerve, and the posterior auricular vein. The internal face is very uneven and moulded on the subjacent parts. It covers the guttural pouch, the mastoid insertion of the small oblique muscle of the head, levator humeri, stylo-hyoideus, the tuberosity on the posterior border of the os hyoides, the digastricus, the tendon of the sterno-maxillaris, and the submaxillary gland, which is separated from it by the thin cellulo- aponeurotic layer uniting the latter muscle to the levator humeri; also to MODES OF TERMINATION OF THE NERVES 1N THE SALIVARY GLANDS. 1, 2, Branching of the nerves between the salivary cells; 3, Termination of the nerve in the nucleus ; 4, Union of a ganglion cell with a salivary cell; 5, Varicose nerve-fibres entering the cylindrical cells of the excretory ducts, the external carotid artery and its two terminal branches, the posterior auricularis, the muscles of the jaw, and, lastly, the facial nerve, which often passes through the substance of the gland. The anterior border of the gland is intimately united to the posterior border of the maxilla; it is related to the temporo-maxillary articulation, the subzygomatic vessels and nerves, and the maxillo-muscular vessels, The posterior border is thicker than the preceding, and is separated from the transverse process of the atlas by the terminal aponeurosis of the levator humeri, to which it is only feebly adherent: it can also be easily separated from it, in order to raise the parotid and pass through the stylo-hyoideus muscle, in the operation of hyo-vertebrotomy. The superior extremity is bifurcated, and embraces the base of the concha of the ear. The inferior extremity is comprised in the angle formed by the union of the jugular and glosso-facial veins. THE SALIVARY GLANDS. © 367 Vessels and nerves of the parotid gland.—This gland receives its blood by a multitude of arterial branches from the large vessels it covers. Its merves are very numerous, and are derived from the facial and inferior _ maxillary nerves, and the carotid plexus. canal.—The parotid gland is provided with a single excretory -eanal, the duct of Stenon, so named from the anatomist who gave the first ; description of it. It is ed from the anterior Fig. 172. border of the gland, near its : inferior extremity, where the eye may readily follow it be- tween the lobules to the three er four principal branches from which it originates (Fig. 172). At first in contact with the terminal tendon of the sterno-maxillaris, it after- wards turns round the pos- terior border of the digastric muscle (stylo-maxillaris por- tion), advances into the sub- maxillary space, creeps over the internal masseter muscle (pterygoid), beneath the glosso-facial vein, and arrives at the maxillary fissure, into which it enters witlf the aforesaid vein and _ corre- sponding artery, but behind both. It then ascends ex- ternally along the anterior border of the masseter muscle to the level of the inferior molars, when it beneath its two satel- ite vessels, obliquely crosses their direction, and pierces the cheek towards the third upper molar tooth, opening into the mouth by a large tubercle. y 8 1, Inferior border of lower jaw; 2, Genio-hyoideus; 3, : 5 Mylo-hyoideus; 4, Submaxillary artery; 5, Ditto The parotid duct is com- vein; 6, Parotid duct ; 7. Sterno-maxillaris tendon ; posed of two membranes: 8, Parotid gland; 9, Sterno-maxillaris muscle; 10, the internal, mucous, with 11, 12, Submaxillary glands; 13, Sterno-thyro- columnar epithelium; and hyoideus and subscapulo-hyoideus muscles; 14, Thy- itaiene! rade up of ain roid gland; 15, Pterygoideus internus. N F nective tissue, and circular and longitudinal elastic fibres. 2. Maxillary or Submazillary Gland. (Figs. 172, 173.) Preparatio.—To expose this gland, as well as the sublingual, divide the maxilla, as in preparing the muscles of the tongue for dissection (see p. 334). This gland, smaller than the preceding, is situated in the intermaxillary space, on the lateral plane of the larynx, and within the parotid gland, INFERIOR ASPECT OF HEAD AND NECK. 368 THE DIGESTIVE APPARATUS IN MAMMALIA, It is long and narrow, flattened on both sides, and describes a slight - curve with the concavity turned upwards: a form which allows it to be studied, with regard to relations, on two faces, two borders, and two extremities. By its external face, it responds to the internal pterygoid musele, the digastricus, the sterno-maxillaris tendon, and the cellulo-aponeurotie layer separating it from the parotid. Its internal face, applied to the side of the larynx, responds, superiorly, to the guttural pouch, to the carotid artery, and to the nerves which accompany that vessel in the upper part of the neck, The superior border, thin and concave, is margined by the middle part of the digastricus. The inferior, thick and concave, is in contact with the glosso-facial vein. The posterior extremity is maintained beneath the transverse process of Fig. 178. Ba Ly \ ~ \ \ Sy WSS ~ SSN MAXILLARY AND SUBLINGUAL GLANDS. r, Maxillary gland; s, Wharton’s duct; T, Sublingual gland. the atlas, by an extremely loose and abundant cellular tissue; the anterior is insinuated between the internal pterygoid and the thyro-hyoideus muscle. Vessels and nerves.—The blood is distributed to the maxillary gland by various small innominate afteries, like those of the parotid gland, and which are most frequently derived from the external carotid and the glosso-facial. The nerves are principally furnished by the carotid plexus. t j ) THE SALIVARY GLANDS. 369 _ Exeretory Canal.— Wharton's duct, as it is termed, is long and narrow; has very attenuated walls, and exists for nearly the whole length of the superior border of the gland : sometimes on its internal face, where it receives ‘the ramifications from various lobules. At the anterior extremity of the it becomes free, and passes forward between the mylo-hyoideus and Dasio- (hyo-) glossus muscles. After crossing, outwardly, the glosso-facial artery and great hypoglossal nerve, and, inwardly, the tendon of the digas- tricus and the lingual nerve, it passes between the hyo-glossus longus and the sublingual gland, lying closely to the inner side of the latter; thus it extends parallel to the lateral groove (or channel) of the lingual canal (on the floor of the mouth). It finally arrives near the frenum of the tongue, but underneath the buccal membrane, and opens into the mouth by a small, but very salient, floating tubercle, situated a little in advance of the frenum, and yulgarly named the barb (barbillon). The structure of Wharton’s duct is identical with that of Stenon, but its external tunic is extremely thin, and has not any circular elastic fibres. 3. Sublingual Gland. (Fig. 173.) This is less in volume than the preceding, and is situated under the tongue, in the intermaxillary space. Elongated from before to behind, and very flat laterally, it has, like the submaxillary gland, two faces, two borders, and two extremities, whose relations we will briefly indicate. The external face is covered by the mylo-hyoideus muscle; the internal responds to Wharton’s duct and the genio-glossus and hyo-glossus longus muscles. The upper border projects beneath the mucous membrane on the floor of the mouth, where it forms the sublingual ridge ; the inferior, thin and sharp, is comprised between the mylo-hyoideus and the genio-glossus muscles. The two extremities are thin and tapering; the posterior contains a branch of the lingual nerve; the anterior extends to the bottom of the angle formed by the union of the two branches of the inferior maxilla. Vessels and nerves.—This gland possesses a special, but small artery—the sublingual Its nerves come from the lingual nerve, and even from the carotid Ezxeretory canals—These number fifteen or twenty, and are named the ductus Riviniani. Flexuous and very slender, they are detached from the superior border or internal face of the gland, ascend perpendicularly, and open into the mouth on the sublingual crest or ridge by a linear series . of small orifices pierced, as usual, in the centre of a tubercle. 4, Molar Glands. These are so named because they are disposed parallel to the molar arches. There are two on each side. The superior molar gland, the most considerable, represents a narrow line of salivary lobules placed outside, and along the upper border of, the alveolo-labialis muscle. In its posterior part, where it is concealed beneath the masseter muscle, this gland is thicker and more compact than in front, where the few lobules which compose it scarcely come in contact with each other. The inferior molar gland, less lobulated and voluminous, and not so wide as the preceding, is placed at the inferior border of the buccinator, immediately beneath the mucous membrane of the mouth, and near the 28 370 THE DIGESTIVE APPARATUS IN MAMMALIA, point where it is reflected from the side of the cheek on to the inteciaeam a. maxillary bone. It is bordered, for the whole of its extent, by the buccal — nerve. Both glands pour their secretion into the mouth by numerous salient ‘ Ee orifices, which can be seen arranged in line on the buccal membrane, parallel = to each molar arcade. as It may be remarked that these glands establish a transition between the preceding and those yet to be mentioned. Their lobules are far from % representing so compact an agglomeration as that formed by the parotid or = sublingual lobules; and they tend to separate from each other to become more independent. " Therefore it is that many writers regard them as distinct, and describe them as superior and inferior molar glands. 5. Labial, Lingual, and Palatine Glands. The lobules composing these glands are spread in layers more or less thick on the inner face of the mucous membrane, instead of a 5 agglomerated in masses, as in the previous glands. Sometimes they are scattered, in consequence of their small number. In general, the excretory duct of each glandule opens independently into the mouth, without com- municating with those of the neighbouring lobules. Labial Glandule.—These are more abundant in the upper than in the lower lip, and pass beyond the commissures to be spread for a short over the inner aspect of the cheeks. It is easy, in the living Horse, after turning up the lip and carefully wiping it, to see the salivary fluid secreted by these small organs escape by their excretory ducts. Lingual Glandule.—They form a layer under the mucous membrane at the base of the tongue, and adhere very closely to the fibres of the small hyo-glossus muscle, and, laterally, are continuous with the layer which covers the external face ‘of the amygdaloid mucous membrane. They are . also found on the side of the tongue, above the superior border of the hyo- glossus longus muscle; though these are few and scattered, and look as yt . incrusted in the substance of the hyo-glossus muscle. Staphyline (or Palatine) glandule.—The thick layer these form under the anterior mucous covering of the soft palate has been described with that organ. We have only to observe here, that it is continuous, laterally, with the glands at the base of the tongue, through the medium of the glandule of the amygdaloid cavity; and in such a manner, that the part of the mouth immediately in front of the isthmus of the fauces, and which might be justly considered as the isthmus itself, is enveloped in a complete glandular . zone. In the dead body, we always find in this compartment a greater or | less quantity of viscid fluid, which is certainly secreted by this zone, It is here, then, that the alimentary bolus is enveloped in the glutinous matters intended to favour its passage in the pharynx and csophagus; and it is worthy of notice that the constricted passage where this secretion is poured out in the living animal, immediately precedes the canal traversed by the bolus of food in the act of deglutition. : DIFFERENTIAL CHARACTERS IN THE SALIVARY GLANDS OF OTHER THAN SOLIPED ; ANIMALS, The salivary system of the Herbivora is more extensive than that of the Omnivora, and especially the Carnivora. Ruminants.—1. Parolid gland —The parotid glands of the Oz are distinguished by di THE SALIVARY GLANDS. 371 arn. development and red colour, which contrasts markedly with the pale yellow que of the maxillary glands. In the Sheep and Goat, Stenon’s duct passes through the ‘masseter muscle, (In the Oz, this — offers, at the upper ag of its anterior border, a ‘round lobe lying on the masseter. Stenon’s duct opens into the mouth at the fifth molar. It terminates in the Sheep and Goat at the fourth molar. 2. Maxillary gland.—In the Ox this gland is much thicker than in Solipeds, its ‘yolume being in inverse relation to that of the parotid. In its posterior moiety it enlarges into an oval lobe which, below the larynx, lies against that of the opposite side. ‘Wharton's duct follows the same course as in the Horse; the papilla through which it ms is hard, resisting, and notched, and is lodged in an elliptical fossette near the _——s«&SB«. Sublingual gland—In the Ox, Sheep, and Goat, this gland comprises two - a _-_-_ portions: a posterior, somewhat voluminous and lobulated, provided with a special . litera) duct which follows and opens near Wharton's duct (by the ductus Bartho- Unianus); and an anterior, pouring out its secretion by many canals, and representing 354 ma gaged This arrangement allows the saliva to be collected separately from gland. 4. Molar glands.—These are more developed in Ruminants than in Solipeds. The Upper one is enlarged at its posterior extremity. - Pic.—The F laiey gland of this animal is little developed, as in Ruminants, and Stenon’s duct follows the posterior border of the lower jaw. (Leyh says that it is, pro- portionately, largely developed ; that its upper end does not reacl: the conch of the ear, ani that Stenon’s duct opens at the sixth molar.) __ The sublingual gland is analogous in its disposition to that of the Ox. Cuvier, in his *Lecons d’Anatomie Comparée,’ indicates this:—“'The Pig has two sublingual glands, One, very long and narrow, accompanies, outwardly, the excretory canal of the sub- . from the angle of the juw to the secoud sublingual. It is composed of small lobules of a pale red colour. Its excretory duct arises near the posterior third, and passes along with, but to the ontside of, the submaxillary duct. It terminates near the orifice of the latter by a small opening ; its diameter is equally small. The second sub- ey a gland is placed before the first; its form is square an:| flattened, and the lobes of In the Dog the submazillary glands are larger than the parotids, “They even have in front, along Wharton's duct, a small accessory gland, with a distinct excretory canal into the same papilla as Wharton’s.’” (Leyh states that the submaxillary duct not project into the mouth). The supplementary gland is absent in the Cat. The sublingual gland is not present in the ; it is very small in the Cat, and carried further back than in the other animals. (Leyh describes a sublingual gland as present in the Carnivora, and which is divided into two portions, es in the Pig: the anterior being formed of detached lobules that open into the mouth by several ducts; and the posterior, eyed above than below, with two ducts, the smaller opening into Wharton's duct, and the larger a little in front of it.) ‘ The upper molar gland of the Dog, scarcely noticeable for the greater part of its R extent, forms posteriorly, under the zygomatic arch, near the eye, an independent lobe, Ss fur its large size and its single excretory duct. Duvernoy, who first described it, proposed to name itthe subzygomatie gland, It is not present in the Cat. (This is doubtless the o described by Leyh as the orbital gland, which, he says, is only found in the Dog; the superior molar gland, according to him, not existing in that This orbital gland is external to the ocular muscles, has three or four excretory ‘eanals (the ductus Nuckiani) which converge into one duct that opens into the mouth above the last molar.) The labial, lingual, and palatine glandul# are much less developed in the Carnivora than the Herbivora. This predominance of the salivary system in the latter is suffi- ciently accounted for, when we consider the hard, fibrous, and coriaceous food these animals live upon, and’ which must be ingested in large quantity, because of the small amount of nutrition it contains. For its mastication and deglutition a great amount of saliva is absolutely necessary. a ~ L wet ™ = 372 THE DIGESTIVE APPARATUS IN MAMMALIA, COMPARISON OF THE SALIVARY GLANDS OF MAN WITH THOSE OF ANIMALS. ny. As in animals, the parolid is the most voluminous of the salivary oy Its tissue is reddish-grey and lobulated, the lobules adhering closely to each Its ts shapo is irregular, and it is moulded to the excavation behind the angle of the jaw. duct passes across the masseter, and shows on its course some sulivary Goalie deca what is named the accessory parotid (or socia parotidis); it opens opposite the upper molar. The submazillary gland weighs about half-an-ounce. It is partly situated beneath | the deep cervical fascia, and partly within the body of the lower jaw, between the mylo- hyoideus and hyo-glossus muscles. Its lobules are more loosely united than those of the parotid. Wharton’s duct opens on the sides of the frenum lingue by a small opening at the 2 x of a round papilla (caruncula sublingualis). e sublingual daa is analogous to that of the Ox and Pig. There are, in fact, two santinnctle: an anterior about the size of an almond, and furnished with a single excretory canal—the ductus Bartholini, that terminates near Wharton’s duet; the other, posterior, formed by several isolated lobules with multiple excretory duets, the ductus Riviniani, There are also Jabial, palatine, and lingual glands; with, besides, near the meee a small conglomerate gland, the gland of Nuhn, which has a special duct. THe puarynx. (Figs. 174, 175.) Preparation.—1. Study the general disposition — and situation of this vestibule in tle antero- posterior vertical section of the head (fig. 175). 2. In order to examiue the interior conveniently, the head should be separated from the n leaving attached to it a pesos portion of the trachea and cesophagus; then by sawing across, either through or behind the temporo-maxillary eeadiaatt i that portion of or — is re- moved, and the posterior parietes of the pharynx is exposed, and may be dissected to study the muscles (Fig. 178), or opened in the middle line to reach the interior of the cavity (Fig. 174). 3. The muscles should be dissected with those of the tongue, and in the same manner. The pharynx is a membranous vestibule common to the digestive and air passages, and situated behind the soft palate, which separates it from the mouth; above, it is at- tached to the base of the cranium, and, belo: to the laryngeal apparatus. Form and internal disposition—In con- sequence of the conformation of the soft palate, which, in the domesticated animals, and particularly in Solipeds, is prolonged to | the base of the epiglottis, the pharynx forms PHARYNGEAL AND LARYNGEAL RE- GION; THE POSTERIOR PART OF THE HEAD INCISED AND THROWN FORWARD, 1, Base of the cranium; 2, Roof of the pharynx; 3, Muscles of the cheek ; 4,4, Walls of the pharynx; 6, Septum nasi; 7, Posterior openings of nostrils; 8, Entrance to the mouth; 9, Epiglottis ; 10, Posterior pillars of soft palate; 11, Arytenoid cartilages ; 12, O ning of the esophagus ; 13, Esophagus ; 14, Trachea. acylindrical cavity elongated from before to behind, enclosed laterally and posteriorly by wide thin muscles, and with the the a palate for an anterior wall. At the two extremities of this cavity are openings which allow the pharynx to communicate with the other passages or cavities, and whose dis- position we will at once begin to study. At the upper extremity of the large axis of the pharyngeal cavity is to be re- marked; 1, In front, the two posterior - THE PHARYNX. 373 openings of the nasal cavities; 2, Behind, and directly opposite the pre- ceding, the two pharyngeal openings of the Eustachian tubes, which are closed by a cartilaginous kind of clap-valve.' At the inferior extremity of this axis is found: 1, In the centre, a vast ping orifice projecting into the anterior of the pharyngeal cavity, like a tap into a cask: this is the entrance to the larynx, the salient portions of which form, on the walls of the pharynx, two lateral gutters limited superiorly by the posterior pillars of the soft palate; 2, In front of, and beneath this, is the isthmus of the fauces ; Behind and above, the asophageal opening at the bottom of an infundibulum, which may be considered as a special region of the pharynx. These seven openings of the pharyngeal cavity give it the appearance of a cross road, into which abut different thoroughfares. It is necessary to note that the air and digestive passages intersect each other here, and in such a way that, during deglutition, the bolus of food passes over the entrance of the larynx to reach the cwsophageal opening. This peculiarity is easily seen by referring to figure 175. Fig. 175. MEDIAN LONGITUDINAL SECTION OF HEAD AND UPPER PART OF NECK. 1, Upper lip; 2, Premaxilla; 3, Hard palate; 4, Tongue; 5, Septum nasi; 6, Nasal bone; 7, Palate bone; 8, Soft palate; 9, Pterygoid bone; i0, Epiglottis; 11, Entrance to Eustachian tube; 12, Arytenoid cartilage; 13, Cricoid cartilage ; 14, Esophagus; 15, Frontal bone and sinus; 16, Cerebrum; 17, Corpus cal- losum ; 18, Cerebellum; 19, Sphenoid bone; 20, Medulla oblongata; 21, Cervical ligament ; 22, Spinal cord ; 25, Occipital bone ; 24, 24, Atlas; 25, 25, Dentata ; 26, Trachea, Relations.—Viewed externally, for the study of its connections, it will be found that the pharynx responds, posteriorly, to the guttural pouches and guttural lymphatics; laterally, to the large branch of the os hyoides, the 1 This region corresponds to the posterior nares (arriére fond) of Man, a diverticulum which cannot be distinguished from the pharynx in the domesticated animals. Under the designation of the posterior nares of the nasal fossx, it will be understood that we mean the posterior extremities of these cavities. (In the ‘ Annales de Médecine Vétérinaire,’ of Brussels, for 1871 (p. 244), M. Lorge describes a pharyngeal cecum as existing in Solipeds, which he states corresponds to the naso-pharyngeal region, or posterior nares, of Man.) rw s + oF is ; 874 THE DIGESTIVE APPARATUS IN MAMMALIA, a internal pterygoid and stylo-hyoid muscles, the craters , great =~ hypoglossal, and superior laryngeal nerves, and the glosso-faci —<— 3 oe Srructure —The walls of the pharynx are composed of a mucous mem- brane, external to which is a muscular layer. 1. Mucous membrane.—This membrane is covered, externally, by a thin layer of yellow clastic fibres, and is much more delicate and less protected by its epidermis than the buccal mucous membrane, of which it isacon- tinuation ; it also communicates with that of the cesophagus, the larynx, the nasal fosse, and the Eustachian tubes. ; Its epithelium is stratified throughout; but it is thin and ciliated in the upper part, thicker and tesselated on the inferior moiety, which more particularly belongs to the digestive apparatus. Everywhere there are racemose glands, though they are most numerous towards the roof of the pharynx. There are also some follicular glands beneath the mucous membrane, in the neighbourhood of the guttural opening, = the nasal cavities, and the Eustachian tubes. 1. ae 2. Muscular layer.—This is composed of seven pairs of muscles, indicated - in the following enumeration: the palato pharyngeus, pterygo-pharyngeus, hyo-pharyngeus, thyro-pharyngeus, crico-pharyngeus, aryteno-pharyngeus, stylo- pharyngeus. f SR (Pharyngo-staphylinus).—This muscle, which has already been described as belonging to the soft palate, is prolonged back- wards on the lateral wall of the pharynx, where its fibres are mixed with those of the pterygo-pharyngeus, and go to be attached to the superior border of the thyroid cartilage by passing beneath the hyo-pharyngeal and thyro-pharyngeal muscles. It therefore also belongs to the pharynx, PreRryGo-PHARYNGEUS, OR SuPERIOR Constrictor (the palato pharyngeus of Percivall).—This muscle is thin, wide, flat, and triangular. It originates 7 from the pterygoid process, whence its fibres diverge, some posteriorly, . others inwardly. The former mix with those of the palato-pharyngeus, and comport themselves like that muscle; and the latter are united, on the median line, with the analogous fibres of the opposite muscle, Tk ing a kind of zone around the origin of the Eustachian tube. 1 muscle is covered, externally, by a layer of yellow elastic tissue, which is attached with it to the pterygoid bone; afterwards it is fixed to the superior border of the great branch of the os hyoides, and is even prolonged on the external surface of the muscle it covers to the thyroid cartilage. The elasticity of this fibrous covering plays a certain part in the move- ments of the hyo-laryngeal apparatus, in acting as a passive antagonist of its depressors. . This muscle is, and can only be, a perfect constrictor of the pharynx, ) as it diminishes the diameter of that cavity in every direction: the longi- tudinal diameter, by means of its posterior fibres, which draw the thyroid cartilage forward; and its transverse diameter, by the circle thrown around the orifice of the Eustachian tubes (Figs. 149; 176, 8). x Hyo-pHarynervs, on First Mippie Consrricror ; Tuyro-pHaryNGEus, — orn Seconp Mippte Constricror; AND CRICO-PHARYNGEUS, OR INFERIOR* Constrictor.—The two first of these muscles only form one in Man, the middle constrictor of the pharynx. They are three muscular bands which terminate above the pharynx, on a median fibrous fold sometimes wide enough to look like an aponeurosis. The first band arises from the cornu of the os hyoides; the second, from the external surface of the thyroid carti- lage; the third, from the superficial face of the cricoid cartilage. — a i Wo j ; ; ¥ 4 : THE PHARYNX, 375 These are universally regarded as constrictors. Sometimes two fasciculi are observed in the crico-pharyngeus. The pee mentary fasciculus is somewhat thin, and arises from the posterior border of the bezil of the cricoid cartilage, ascending parallel to the ceso- phagus to terminate with the principal fasciculus, ARYTENO-PHARYNGEUS.—By this name has been described a small fasci- culus, extremely thin in Solipeds, which extends from the posterior border of the arytenoid cartilage to the origin of the esophagus. To expose this muscle, which we do not look upon as constant, it is necessary to turn the hagus forward on the superior surface of the pharynx. LO-PHARYNGEUS.—A narrow band which descends from the great hyoideal branch to the side of the pharynx, where it is confounded with the pterygo-pharyngeus. It elevates the pharynx in contracting, and it is also ed as a dilator; though the disposition of the parietes of the pharynx, and the feeble volume of this muscle, scarcely allows it to play any efficacious part in the dilatation of that cavity. It may only produce a very slight infundibulum where it is inserted. The real dilating agent of the pharyngeal cavity is‘the alimentary bolus, which is pushed into it by the action of the tongue (Fig. 149, 5). Fig. 176. MUSCLES OF THE PHARYNGEAL AND HYOIDEAL REGIONS, 1, Glenoid cavity of temporal bone; 2, Superior extremity of styloid bone; 3, Tensor palati with its pulley, 5; 4, Stylo-pharyngeus; 6, Palato-pharyngeus ; 7, Circumflexus palati; 8, Pterygo-pharyngeus ; 9, Sublingual gland; 10, Portion .of hyoid bone; 11, Hyo-pharyngeus; 12, Thyro-pharyngeus; 13, Crico-pharyn- geus; 14, Portion of stylo-pharyngeus ; 15, Hyo-thyroideus ; 16, Styloid bone ; 17, Crico-arytenoideus lateralis; 18, (sophagus; 19, Sterno-maxillaris and hyoideus, and subscapulo hyoideus; 20, Trachea; 21, Hard palate; 22, Tongue. It is not rare to meet a second stylo-pharyngeus muscle terminating on the same point as the first, but proceeding from the inferior extremity of the large branch of the os hyoides, instead of its upper part. Certain anatomists designate it the inferior kerato-pharyngeus, and con- sider it as a constrictor of the pharynx. It sometimes exists only on one side, 3. Vessels and nerves.—The blood sent to the pharynx comes from the 376 THE DIGESTIVE APPARATUS IN MAMMALIA, pharyngeal and thyroideal arteries. The, nerves are supplied by the glosso- pharyngeus, pneumogastric, and great sympathetic. i, Ss Funcrions.—The pharynx plays a passive part in respiration, by serving as an intermediate canal between the nasal passages and the larynx. te Its principal function, however, is connected with the digestive phemo- mena, by its being an active agent in the first stage of deglutition—a complex and rapid movement, which is executed in the following manner: The bolusof food, propelled by the tongue into the pharynx, is seized by the constrictor f muscles, which come into action successively from before to behind, in a y peristaltic and involuntary manner, to carry the mass to the entrance of the esophagus. The food thus passes over the opening of the la during pharyngeal deglutition, but it cannot enter it, because the rae ie back the epiglottis on this aperture, which it almost exactly closes; because, also, the passage of the food prevents pulmonary inspiration, which might, if allowed to take place, divert it from its natural course, and: throw it into the nasal air-passages; the application of the walls of the pharynx to the pellet of food during its momentary passage over the larynx, intercepts all — communication between the external air and the lungs, and only permits the elevation of the ribs with the utmost difficulty. The extreme rapidity of the act of deglutition is another reason for the food escaping the larynx. (Gray concisely remarks: When deglutition is about to be performed, the pharynx is drawn upwards and dilated in different directions to receive the moisel propelled into it from the. mouth. The stylo-pharyngei, which are much further removed from one another at their origin than at their insertion, draw upwards and outwards the sides of this cavity, the breadth of the pharynx, in the antero-posterior direction, being increased by the — larynx and tongue being carried forwards in their ascent. As soon as the morsel is received in the pharynx, the elevator muscles relax, the bag descends, and the constrictors contract upon the morsel and conyey it gradually downwards into the cesophagus.) The deglutition of liquids is carried on in a similar manner. It is curious to remark that, in Solipeds, the food does not come into direct contact with the greater portion of the superior wall of the pharynx during its passage through that cavity. When the alimentary mass is carried back by the tongue, it raises the soft palate and bears its posterior border backwards to the entrance of the esophagus. The extreme develop- ment of this palatine curtain, therefore, quite prevents this surface of the pharynx from being directly applied to the food, and it is through the medium of this partition that the constrictors exercise their peristaltic action on the morsel of aliment until it reaches the cesophageal infundibulum, DIFFERENTIAL CHARACTERS OF THE PHARYNX IN OTHER THAN SOLIPED ANIMALS. The pharynx of Ruminants is long and very spacious. The hyo-, thyro-, and crico- pharyngeal muscles—the first and second of the two middle constrictors, and the inferior constrictor—are less distinct from each other than in the Horse; the last-named musele is very small, and the fibrous raphé on which the constrictors unite is little cree In the pharynx of the Sheep is noticed a mucous duplicature that descends to’ the middle of the posterior wall, and appears to be a continuation, posteriorly and inferiorly, of the nasal septum. In the Pig, the posterior part of the peeves is narrow, and has a pouch immediately above the glottis, between the thyro- and crico-pharyngeal muscles. In the Dog, the infundibulum is very spacious, and the pharyngeal mucous membrane, much finer than that of the esophagus, is distinguished from it by a well-marked line of demarcation. The crico-pharyngeal is not very distinct from the thyro-pharyngeal muscle ; so that, in reallty, only three constrictors can be distinguished. i or aay THE @SOPHAGUS. un middle, or 377° COMPARISON OF THE PHARYNX OF MAN WITH THAT OF ANIMALS, In consequence of the smallness of the syft palate, the pharynx of Mun is ouly a kind of channel between the mouth and the larynx and ces »phagus. divided iuto three portions : a superior, the poster‘or nares, cove It is usually by ciliated epithelium ; ultural, and an inferior, or asvphageal; tle two latter are covered with - _ tesselated epithelium. The muscles are almost the same as in the Dog, being a portion of the palato-pharyn- geus, the god) middle, and inferior constrictors, and a styl Below t ph rstihe al muscle. sides of the pharynx, and between the pillars of the soft palate, are the ae : almond-shaped organs, whose surface s!,:ows the openings of the follicles that, with the vessels and a little connective tissue, compose their substance. THE (SOPHAGUS. (Figs. 178, 179.) Preparation.—Place the subject in the first or second position ; remove the subcu- taneous cervical muscle from the left side; take away the corresponding anterior limb, and proceed to the excision of the ribs of this side, with the exception of the first. Afterwards dissect the vessels and nerves in the neighbourhood of the esophageal canal, taking care to preserve their relations to each other. Form.— The cesophagus is a long, cylindrical, narrow, membranous canal, easily dilated for the greater part of its extent, and destined to convey the food from the pharynx to the stomach, and to complete the act of deglutition. Course.-—This canal begius at the pharynx, and communicates with it by means of the pos- terior opening situated above the glottis. It afterwards descends behind the trachea to the middle of the neck, where it commences to deviate towards the left side of that tube, and enters the thoracic cavity by inclining towards the inner aspect of the first left rib. It soon after ins its situation above the trachea, passes over the base of the heart, and reaches the open- ing of the right pillar of the diaphragm, in passing between the two layers of the posterior mediastinum. Traversing this opening, it pene- trates the abdominal cavity, and immediately afterwards is inserted into the smaller curvature of the stomach by an orifice designated the cardiac, which will be studied at the same time as that viscus. Relations—The cesophagus in its course has the following numerous relations : At its origin, it is comprised between the guttural pouch and the posterior crico-arytenoid muscles. In the cervical region, it is enveloped in a Fig. 177. HUMAN PHARYNX LAID OPEN FROM BEHIND. 1, Section through base of skull; 2, 2, Walls of pha- rynx drawn aside; 3, 3, Posterior nares, separated by the vomer ; 4, Extremity of one Eustachian tube; 5, Soft palate; 6, Posterior pillar of soft palate; 7, An- terior pillar; 8, Root of the tongue, partly concealed by the uvula; 9, Epiglottis overhanging (10) the cordi- form opening of the larynx; 11, Posterior part of larynx ; 12, Opening of esophagus, 13; 14, Trachea. thick layer of cellular tissue, which unites it in a loose manner to the surrounding organs, its relations with these varying as we consider them superiorly or inferiorly. Superiorly, and in the median plane, it occupies the space included between the trachea and the longus-colli, being bordered on each side by the common carotid artery, with its satellite nerves—the 378 THE DIGESTIVE APPARATUS IN MAMMALIA, trunk common to the great sympathetic and pneumogastric, and the inferior laryngeal. Inferiorly, it is related to the trachea internally; and, externally, to the inferior scalenus muscle, and the vessels and nerves of the left cervical channel, which also includes the jugular vein.! At its entrance into the thoracic cavity, the cesophagus, still deviating to the left, and lying on the side of the trachea, responds, externally, to the inferior cervical ganglion, the afferent and emergent nervous branches of that ganglion, the vertebral arteries and veins, and the superior cervical and dorso-muscular vessels, which obliquely cross its direction. Beyond this Fig. 178. TRANSVERSE VERTICAL SECTION OF HEAD AND NECK IMMEDIATELY IN FRONT OF THE STYLOID PROCESSES, AND BEHIND THE (&SOPHAGUS. 1, Esophagus; 2, Inner surface of trachea; 3, Common carotid artery; 4, Recur- rent nerve; 5, Thyroid gland; 6, Exterior of pharynx; 7, Crico-pharyngeal muscle; 8,9, 10, 11, Guttural pouch and objects in its interior; 12, Stylo- pharyngeus muscle; 13, Sphenoid bone; 14, Jugular ganglia; 15, Internal carotid; 16, 17, Pneumogastric nerve; 18, Parotid gland; 19, Great hypoglossal nerve; 20, Jugular vein; 21, Subscapulo-hyoideus; 22, Stylo-maxillaris. it regains its position between the trachea and the longus colli, above the left bronchus, to the right of the thoracic aorta, until it reaches between the layers of the posterior mediastinum, which bring it into relation with the internal face’ of the lungs; these are channeled for its reception, and here it is accompanied by the esophageal artery, and the cesophageal branches of the pneumogastric nerve. The very short portion lodged in the abdominal cavity responds, on the ' It is not rare to find the csophagus deviate to the right below the neck; in this case its relations will be inverted. We have never seen this canal enter the thorax in the median plane of the body. “- THE @SOPHAGUS. 379 right, to a fissure in the superior border of the liver, and is enveloped by the peritoneum. . Interior.— Internally, the canal whose course and relations we have just studied presents nothing of interest; and it only requires to be remarked, that its walls are always shrunken and in contact when food is not passing between them. Srrvoerurs.—The cesophagus has two tunics: a mucous and a muscular. The mucous membrane is continuous with that of the pharynx and the stomach ; it is white, and shows numerous longitudinal folds which allow q the canal to dilate. It adheres but loosely to the muscular coat, on which it can glide with the greatest facility. It has a thick, resisting, stratified, tesselated epithelium, an unstriped muscular layer, and some racemose glands. Fig. 179. PECTORAL CAVITY AND MEDIASTINUM, SHOWING THE COURSE OF THE TRACHEZ AND CSOPHAGUS, (A third or middle coat is sometimes mentioned by anatomists; it is composed of the tissue connecting the latter tunic with the one to be next described.) The muscular coat commences at the posterior part of the pharynx by the aryteno-pharyngei muscles, and by two small superficial bands which are detached from the posterior portion of the crico-pharyngei muscles, This tunic is formed of superficial longitudinal fibres, often assembled in fasciculi ; and of a deeper series of spiral or circular fibres, which, towards the inferior extremity of the canal, intercross in an almost inextricable manner. This muscular layer in the cervical, and for a great part of the thoracic portion of the cesophagus, has the red colour of voluntary muscles ; but it becomes white, like the involuntary fibres, after the conduit enters the mediastinum, and acquires considerable thickness and marked rigidity. It is to be noted that this arrangement of the muscular tunic is especially or Ip 380: THE DIGESTIVE APPARATUS IN MAMMALIA. evident towards the insertion of the cesophagus into the stomach, and that the muscular tube is at this point so narrow, that it is almost exactly filled by the folds of mucous membrane it contains. For this reason if is that we may inflate a stomach by the pylorus, without applying a ligature to the cesophagus; the aperture of the canal being so perfectly closed that it does not allow a bubble of air to escape. In describing the interior of the stomach, we will refer to the consequences resulting from this interesting anatomical fact. Vessels and nerves.—The cesophagus is supplied with blood by the divisions given off by the common carotid artery, as well as the bronchial and cesophageal arteries. The nerves are almost exclusively derived from the pneumogastric; the motor nerves are the superior cesop. filaments, branches of the external pharyngeal and laryngeal; the sensitive filaments are derived from the recurrent. Fonorions.—This canal conveys nutriment from the pharynx to the stomach ; it has no other uses, ; DIFFERENTIAL CHARACTERS OF THE GSOPHAGUS IN OTHER THAN SOLIPED ANIMALS, In all the other domesticated animals, the muscular coat is red-coloured throughout its whole extent, and everywhere offers the same degree of thickness and the same flaccidity, The canal is also as wide towards the stomach as at the pharynx. In Ruminants and the Carnivora, it enters the stomach as a funnel-shaped (ivfundi- buliform) tube. The dilatability of the cesophagus is very remarkable in these animals: Dogs swallow large pieces of flesh; and Cows and Oxen ure able to injcst large turnips, or such voluminous foreign bodies as shves. (In Ruminants and the Carnivora the cesophagus is, proportionally, wider than in the Horse and Pig.) COMPARISON OF THE GiSOPHAGUS OF MAN WITH THAT OF ANIMALS. The cesophagus of Man resembles that of Carnivora ; its diameter is almost uniform. It also inclines to the left below the neck, but in the thorax is in the median line, though it again deviates to the left as it joins the stomach. As the thyroid in Man is v voluminous, it is related to the cesophagus in the upper part of the neck. Two accessory fusciculi, belonging to the muscular tunic of the cesophagus, have been described : one is the broncho-cesophageal muscle, which is detached from the left bronchus ; and the other the pleuro-asophageal muscle, detached from the left layer of the posterior mediastinum. . ArticLe I].—Tue Essentrat Orcans or Diaestion. These organs being all contained in the abdominal cavity, this common receptacle will first be studied ; afterwards the stomach, intestines, and their annexed organs—the liver, pancreas, and spleen—will be described. THE ABDOMINAL CAVITY. In mammalia, the interior of the trunk is partitioned by the diaphragm into two great cavities, that lodge the majority of the organs so vaguely termed the viscera. The anterior, the smallest, is the pectoral or thoracic cavity ; the posterior is named the abdomen, or abdominal cavity. The latter, the only one we have now to study, is a vast oval-shaped reservoir, elongated from before to behind, having for its upper wall the muscles of the sub- lumbar region, inclosed below and laterally by the muscles of the inferior abdominal region, bounded in front by the diaphragm, and prolonged behind between the bones and membranous ligaments of the pelvis. The elements composing the parietes of this cavity having been already described, we will confine ourselves to an examination of its interior, in 7. PR a sr Mme gay ol THE ABDOMINAL CAVITY. 381 order to determine the various regions into which it is possible to divide it: a matter of some importance, as it singularly facilitates the topographical study of the contained viscera; for to say that an organ is situated in the abdomen, is a very vague reference to its precise situation, in conse- ety of the great extent of this cavity. It is necessary, therefore, to ivide the abdumen into a certain number of peripheral regions which corre- spond to the different parts of its wall, with a view to define the situation of the organs lodged therein, yet without complicating anatomical de- scription. Six principal regions are recognised in the abdominal cavity. A. The superior, or sublumbar region, corresponds to the superior wall of the abdomen: that is, to the psoas muscles and the bodies of the lumbar vertebre. It extends from the opening between the two pillars of the diaphragm to the entrance to the pelvis. B. The inferior region, limited, laterally, by the hypochondriacs and the flanks, commences, in front, at the xiphoid cartilage, and is prolonged to the pubis; it comprises all that portion of the abdomen which corre- sponds to the linea alba and the two recti muscles. Its great extent necessitates its subdivision into five secondary regions: The suprasternal region, named the epigastric in Man, placed above the xiphoid cartilage of the sternum ; the wmbilical region, situated behind the preceding, and so named in consequence of its including that part of the wall which is pierced by the umbilicus; the prepubic region—the hypogastric or pubic of Man—occupies the space in front of the anterior border of the pubis; the two inguinal regions, diverticuli of the abdominal cavity, located in the inguinal tracts, where they form the special reservoirs to be hereafter described as the vaginal sheaths (or canals). C. The lateral regions (right and left lumbar of Man) are limited : in front, by the costal attachments of the diaphragm ; beliind, by the entrance to the pelvic cavity ; above, by the superior border of the small oblique muscle ; below, by the interval comprised between the inferior border of that muscle and the external border of the great rectus muscle. The designation of hypochondriae is given to the subregion which corresponds to the cartila- ginous circle of the false ribs. The flank is that section covered by the muscular portion of the small oblique muscle. D. The anterior, or diaphragmatic region, comprises the cavity formed by the posterior face of the diaphragm. Like that muscle, it is divided into two regions, a central and peripheral. E. The posterior, or pelvic region, is a special diverticulum of the abdomen described as the pelvic cavity. It is bounded, above, by the sacrum ; below, by the superior face of the pubes, the ischia, and the internal obturator muscle; on the sides, by the constricted portions of the ossa innominata and the sacro-ischiatic ligaments. The entrance to this diverticulum is ‘situated above the pubes, and is of an oval form. Posteriorly, it is narrower, and is traversed by the rectum and the genito-urinary organs, which open externally. Tue Pertronrum.—The abdominal cavity is covered, internally, by a serous membrane, the peritoneum, which will now be briefly described. Like all the splanchnic serous membranes, the peritoneum is composed of a parietal and a visceral layer, which together form a closed sac, so arran that the organs contained in the abdomen are situated external to this sac. The adjoining theoretical figure (180), representing a transverse section of the abdominal cavity, will show at a glance this arrangement. Let a represent the section of the small intestines floating at liberty in the interior of the 382 THE DIGESTIVE APPARATUS IN MAMMALIA, cavity, » that of the aorta, at the level of the great mesenteric artery: the peritoneal membrane, cc, covers the walls of the abdomen, and at the points pp (not inserted, but intended to be placed within the cavity below, and on each side of B, the aorta) is folded around the great mesenteric artery in such a manner as to form two layers, rr, which Fig. 180. come in contact by their adherent face, reach the intestine, and then separate to envelop it. We then see in this figure the parietal layer of the peritoneum, co, the visceral layer, Ge, and the two layers, Fr, which establish the continuity of the parie- tal and visceral portions; the complete sac formed by these is apparent, and it could be rendered more so by the further separation and development of the layers FF; so that there is no difficulty in under- standing how the small intestine may be at the same time in the interior of the abdominal cavity, and outside the sac formed by the serous membrane which THEORETICAL TRANSVERSE SECTION lines that cavity. ° OF THE ABDOMINAL CAVITY, TO This arrangement is common to all the SHOW THE DIsposIrion or THe Organs freely suspended in the abdomen. PERITONEUM. The serous folds which suspend them, in joining their peritoneal layer to that which covers the parietes of the cavity, will be studied under the names of ligaments, mesenteries, and omenta. Some organs—the kidneys, for example —have no proper visceral layer, being comprised between the abdominal wall and the external face of the parietal peritoneum, and are invested with none of the duplicatures just mentioned. We will briefly study the duplicatures, ligaments, mesenteries, and omenta that the peritoneum forms, starting from the umbilicus and passing forwards and backwards (Fig. 181). On reaching the suprasternal region, the peritoneum forms a falciform duplicature, extending from the umbilicus to the middle lobe of the liver, and which is even prolonged between that lobe and the posterior face of the diaphragm ; at the free border of this fold is a thickening which is regarded as the remains of the obliterated umbilical vein. In becoming doubled over the neighbouring organs, the diaphragmatic portion constitutes: 1, The ligaments of the right and left lobes of the liver; 2, The common ligament of that gland, which surrounds the posterior vena cava: 3, The cardiac ligament that envelops the termination of the cesophagus. Behind the liver is found the hepato-gastrie ligament, which fixes the stomach in the posterior fissure of the liver and is, to the right and backwards, attached to the duodenum at the lower face of the right kidney ; it is then directed from right to left, and becomes continuous with the parietal peritoneum of the sublumbar region and the mesentery proper. The two lamine of the hepato-gastrie ligament separate at the lesser curvature of the stomach to cover that viscus; then join at its greater cur- vature, and pass to the interior of the abdominal cavity. This fold receives the name of the great or gastro-colic omentum ; it leaves the left tuberosity of the ventrieulus, which it suspends to the sublumbar region from the whole extent of the great curvature ; to the right it goes beyond the pylorus, THE ABDOMINAL CAVITY. 383 to be continued on the concave curvature of the duodenum as far as the ewcum. By its posterior border, the great omentum is spread around the termination of the large colon and the origin of the floating colon, where it is confounded with the visceral peritoneum of these organs, as well as with the — peritoneum. It results from this arrangement that the great omentum behind the stomach, and in front of the adherent portion of the large colon, a space that communicates with the great peritoneal cavity by a very narrow opening, the foramen of Winslow. This aperture is included between the vena porte, posterior vena cava, anterior extremity of the pancreas, and the lesser curvature of the stomach. ‘To the left of the latter viscus, on the external face of the great omentum, the spleen is suspended ; consequently, that portion extending from the spleen to the ventriculus is named. the ic omentum. The two layers composing the great omentum are very thin for the of their extent, and include the blood-vessels between them. In emaciated animals these vessels are distinctly seen, owing to the trans- parency of the membranes, and they give the omentum a lace-work appear- ance; but in fat subjects they are concealed by the adipose tissue deposited along their course, and which may accumulate in considerable quantity. In the sublumbar region, the parietal peritoneum forms several folds ; these are: the hepatico-renal ligament, extending from the right lobe of the liver to the anterior border of the right kidney; the ligament of the lobus Spigelii, the mesentery proper, the colic mesentery; lastly, the greatly de- veloped lamin surrounding the cecum and the second flexure of the colon, which constitute the meso-ceecum and meso-colon. THEORETICAL LONGITUDINAL AND MEDIAN SECTION OF THE ABDOMINAL CAVITY, TO SHOW THE REFLEXIONS OF THE TERITONEUM, 1, Liver; 2, Stomach; 3, Small intestine; 4, Origin of the floating colon; 5, Rectum; 6, Vagina and uterus; 7, Bladder; 9, Posterior aorta; 10, Diaphragm ; 11, Posterior vena cava; 12, Inferior abdominal wall.—Pp, Pp, Parietal perito- neum; Pv, Pv, Visceral peritoneum.—L, Hepato-gastric ligament; M, Mesentery. —Ge, Great omentum. The great mesentery is detached from the border of the large mesenteric artery, and projects into the abdominal cavity to reach the small intestine at its lesser curvature, and envelop that viscus. BS4 THE DIGESTIVE APPARATUS IN MAMMALIA, Its shape is that of an irregular triangle, whose summit corresponds tothe mesenteric artery, the very short anterior border being continuous with the — ducdenal frenum, and the posterior border, the longest, with the meso-colon, — its convex festooned base being as long as the intestine itself. Between the two lamine that compose it are the blood-vessels and lymphatics, as well as * the nerves, of the small intestine. The colic mesentery is constituted like the great mesentery. Its inferior border, plane or plicated, is fixed to the small curvature of the floating colon and the commencement of the rectum; its upper border extends from the great mesenteric artery as far as the entrance to the pelvic cavity. Around the cross of the c#cum, from the origin and the termina~ tion of the great colon, the peritoneum is reflected to cover these viscera ; a layer passes from the anterior border of the cecum on to the ileum and the second flexure of the colon: this is the meso-ceecwm ; another layer, comprised between the second and third portion of the colon, and whose shape is that of a battledore, is named the meso-colon. If, again, the peritoneum is taken at the umbilical region and followed 3 é F backwards, it will be found to insinuate itself into the inguinal canals, cover — the organs contained in the pelvis, and become reflected at the bottom of — that cavity, to be continued either with the peritoneum of the sublumbar _ region, or with that on the abdominal walls. This serous membrane covers the anterior cul-de-sac of the bladder, and at this point has three ligaments. The middle ligament, falciform in sha leaves the large extremity of the bladder, is attached to the anterior bo of the pubis, and insensibly disappears on the inferior abdominal wall; on ~ its free border is a small fibrous cord, which is supposed to be the remains of the urachus. The two lateral ligaments are more developed, and extend from the entrance to the pelvic cavity to the vesical cul-de-sac; they have on their free border the obliterated umbilical arteries. In the male, the peri- toneum is prolonged from the upper face of the bladder to the enlargement of the deferent ducts, between which it sends a transverse fold to the anterior extremity of the vesicule seminales, and is then reflected around the rectum. In the female, it is carried from the bladder to the terminal portion of the vagina, to the uterus, and to the cornua of that organ, where it forms three folds named the broad ligaments, ligaments of the ovary, and the round ligament; then it re-descends on the upper face of the vagina, and thence envelops the rectum, around which it is reflected from behind forwards, According to this arrangement, we see that the termination of the digestive canal, and the parts of the genito-urinary organs situated altogether at the posterior portion of the pelvic cavity, are placed outside the peri- toneal serous membrane. Srruorure.—Like all the serous membranes, the peritoneum is formed by a membrane of connective tissue, rich in elastic fibres, and coyered on its free face by a simple tesselated layer of epithelium (the cells of which are flat and polygonal, and about +,)5, of an inch in diameter). Many blood-vessels are found on the adherent surface, while lymphatics are abundant in the — visceral layer. Its nerves come from the diaphragmatic, lumbar, and inter- costal branches, and the great sympathetic. DIFFERENTIAL CHARACTERS IN THE ABDOMINAL CAVITY OF OTHER THAN SOLIPED _ ANIMALS, In the Canali the abdominal cavity is very narrow; while in Ruminants it is very vast, its capacity being in direct relation to the volume of the viscera it contains. » mo 2 a i he cant At ee, 7) | a " et _--? ~. -. ld t rgnl du tis 0 ie THE STOMACH. . 885 The general disposition of tle peritoneum varies but little in the different species, the only notable diversities being remarked in the great omentum. In the Ox, Sheep, and Goat, this is detached from the middle of the lower face of the rumen, and envelops the right sac of that neem; Sing the fourth compurtment to its great curvature, and then passing upwards to me continuous with the mesentery. In the Dog and Pig, this descends in front of the intestinal mass until near the pelvis ; then it aseends in gathering on itself, and ultimately spreads over the colon: in tle middle portion of the great omentum there are, consequently, four layers placed against each other. COMPARISON OF THE ABDOMINAL CAVITY OF MAN WITH THAT OF ANIMALS, The abdominal cavity of Mun is elongated vertically, aud has an inferior cavity occupying the entrance to the pelvis. There is nothing particular to note in its disposi- tion, the differences observed in it being allied to the external shape of the body. ‘Tho om is spread over its parietes nearly in the same manner as in the Carnivora; great omentum is constituted by four layers, and covers the intestines like an apron: between its two lamine is the lesser cavity of the omeutum, virtually in the adult. THE STOMACH, The stomach is a membranous sac comprised between the cesophagus and intestines, and in which are commenced the essential phenomena of digestion. 1. The Stomach in Solipeds. (Figs. 182, 183, 184, 185, 186.) Preparation.—In order to study the relations of this organ, it suffices to open the abdomen and remove tlie intestinal mass in the fullowing manner :— Place the animal in the first position, and very slightly inclined to the left side; make an incision through the i abdominal wall, or, still better, carry it away entirely by a circular incision, care not to wound any part of the intestine. The entire viscera should then be wn from the abdominal cavity, and laid on the table which supports the subject ; for this mass cannot be allowed to fall on the ground without risk of being pulled and torn, either in the intestine itself, or those parts which it is desired to preserve intact in the abdomen. Incise the floating colon where it joins the reetum, and the duodenum where it passes behind the great mesenteric artery; the base of the cecum should now be detached from the sublumbar surface by the rupture of the cellular tissae which connects it to the right kidney and the pancreas; the cellular connection between the latter gland and the terminal extremity of the fourth portion of the large colon should also be broken; after this, it is only necessary to divide the attaghment uf the mesenterie bands to the sublumbar region, with the vessels coutained betwéen them. The intestinal mass is then definitively expelled from the abdominal cavity. In this way it is possible to ex and salseniond® prepare, not only the stomach, but also the spleen, liver, pancreas, i ureters, ete. Nothing more remains than to make known the proceedure to be adopted in everting the stomach, in order to study its internal surface, or dissect its deep muscular Jayer. 1t is recommended, first, to excise the stomach with at least three inches of the oe a a and eight inches of the duodenum, and cleanse the interior of the organ. This ma one in several ways, but the fullowing is the simplest ‘a certain quantity of water is introduced into the stomach by fixing the duodenum to a water-tap, the right hand manipulating the organ while the left closes the duodenum to prevent the escape of the liquid. The alimentary substances contained in it are in this way mixod with the water, and may be expelled from tlhe duodenum by pressing the stomach ; this tion being repeated four or five times, thoroughly cleanses the cavity of the organ. © evert the inner surface, it is only necessary to introduce by the duodenum a loop of wire, and make it pass through the esophagus; a strong waxed thread is fastened in the loop and firmly fixed around the cesophagus, when, in pulling back the wire, this extremity is drawn towards the pylorus, and by careful traction the latter is so dilated as to allow the passage of the cardiac end, and complete eversion of the stomach. Inflation will then give it its normal form and disposition ; with this difference, that the mucous membrane is external, and the serous tunic internal. Lastly, to render the muscular layers of the stomach more evident, it is advisable to plunge the into boiling water for some minutes, after which it should be put into cold water. If it is desired to study the external and middle layers, the stomach should be inflated, and its serous covering removed by strips with forceps and the fingers; if the deep layer is to be examined, the mucous membrane must be removed by means of the forceps and scalpel from a stomach previously everted. ¢ 9 ‘ 386 THE DIGESTIVE APPARATUS IN MAMMALIA. . 4 : | ; Situation.— The stomach, also designated the ventriculus, is situated in the diaphragmatic region of the abdomen, where it affects a direction transverse to the median plane of the body. Dimensions.—Its average capacity, in an ordinary-sized Horse, is from 83 to 34 gallons; but it varies greatly according to the bulk of the animal, its breed, and the nature of its food. Relatively, it is more considerable Fig, 182. 2, Middle lobe; 3, Right extremity, or ventriculus of stomach; 4, Left extremity; 6, Left kidney; 7, Supra-renal capsule; 8, Ureter; 9, Posterior vena cava; 10, Posterior R \\ THE. ABDOMINAL CAVITY WITH THE STOMACH AND OTHER ORGANS, aorta; 11, 12, Psoas parvus and magnus; 13, Iliac psoas; 14, Tensor vagine ; 15, External iliac artery ; 1, Right lobe of liver; 16, Internal iliac artery. in common-bred Horses, and in the Ass and Mule. When empty, its average weight is between 3 and 4 pounds. Form.—Elongated laterally, curved on itself, often constricted in its middle, and slightly depressed from before to behind, this reservoir presents, externally: 1, Two faces—an anterior and posterior, smooth and rounded ; 2, A great or convex curvature, forming the inferior border of the THE STOMACH, 387 organ, and giving attachment, throughout its extent, to the great omentum— a membranous fold which has been described as a dependency of the serous membrane; a lesser or concave curvature, into which the cesophagus is inserted, and which is united, to the right of that canal, to the liver, by means of a frenum known as the hepato-gastric ligament; 4, A left eax ” tremity, dilated in the form of a large conical tuberosity, and constituting Be the left cul-de-sac (or fundus) of the stomach ; 5, A right extremity, narrower, j curved upwards, and continued by the duodenum, from which it is separated by a marked constriction: this is named the right cul-de-sac of the Relations.—Studied in its connections with the neighbouring organs, the stomach is related: by its anterior face, with the diaphragm and liver; by Fig. 183, STOMACH OF THE HORSE, A, Cardiac extremity of the esophagus; B, Pyloric ring. its posterior face, with the diaphragmatic curvature of the colon. Its inferior border, margined. to the left by the spleen, which is suspended from ah means of the great omentum, is separated from the inferior abdominal by the large anterior curvatures of the colon; its distance from this wall depends upon the fulness of the organ. The left extremity, suspended to the sublumbar region by the aid of a very short serous ligament, a portion of the great omentum, responds to the base of.the spleen, the left extremity of the pancreas and, less directly, to the anterior border of the left kidney. 202 388 THE DIGESTIVE APPARATUS IN MAMMALIA, The right extremity, lower than the left, touches the right lobe of the liver and the above-mentioned intestinal curvatures, Interior.—When a stomach is opened to study its interior, one is at first struck by the different aspect its internal membrane presents, according as it is examined to the right or left. To the left, it has all the characters of the cesophageal mucous membrane, in being white, harsh, and even pace it is covered by a thick layer of epithelium. To the right, it is thi wrinkled, spongy, very vascular and follicular, has a reddish-brown tint which is speckled by darker patches, loses its consistency, and is deprived of the remarkable epidermis it exhibits on the left side, to be covered by a very thin epithelial pellicle. It is not by an insensible, but a sudden transition that the mucous membrane of the stomach is thus divided into two portions; and their separation is in- dicated by a salient, more or less sinuous, and sharply-marked ridge. This crest, then, divides the stomach into two com- partments: a division already indicated externally by the circular depression observed in the majority of subjects. The left sae or compartment is considered as a dilatation of the cesophagus. The right sac constitutes the true stomach of Sclipeds; as on it alone deyolyes the secretory function which elaborates the gastric juice, the essential agent of diges- tion in this organ. The interior of the stomach (Fig. 184) offers for study two apertures: the INTERIOR OF THE HoRsE’s sromacu, C47diae and pyloric. The cardiac, or A, Left sac; B, Right sac; ¢, Duodenal esophageal orifice, is in the lesser curva- dilatation. ture of the left sac of the stomach. Its disposition has given rise to numerous discussions, as in it has ‘generally been sought the reason why Solipeds vomit with such extreme difficulty. At one time there has been des- cribed a semilunar or spiroidal valve, which is opposed to the retrograde movement of the food; and at another time it was the oblique insertion of the esophageal canal, resembling that of the ureters into the bladder, and which, by a mechanism analogous to these, proved an obstacle to the return of aliment into the cesophagus, Both suppositions are wrong. When we attentively observe the manner in which the cesophagus comports itself at its termination, it will be noticed that it is inflected downwards, after travers- ing the right pillar of the diaphragm, and is inserted almost perpendicularly into the lesser curvature of the stomach. In opening into this viseus, the cesophagus does not widen into an infundibulum, as in other animals; on the contrary, its calibre is here narrower than elsewhere, and its cardiac or stomachal orifice, completely obstructed by the folds of mucous membrane, only occupies an infinitely small portion of the internal surface of the stomach. With regard to the pylorus, it represents a large aperture formed at the bottom of the right sac, and furnished with a thick circular ring; this opening can be completely closed through the action of the powerful sphincter surrounding it. Srructure.—The parietes of the stomach are composed of three Fig. 184. 1 “s a ‘ > THE STOMACH, 389 membranes: an external, or serous ; a middle, or muscular ; and an internal, or mucous, 1. Serous membrane.—This membrane, derived from the peritoneum, adheres closely to the muscular layer, except towards the lesser curvature, where it is constantly covered by an expansion of yellow elastic tissue, whose use appears to be to maintain the two extremities of the stomach near each other; for when this is destroyed the lesser curvature becomes considerably elongated. Along the whole of the greater curvature is a triangular space occupied by connective tissue; this space disappears more or less completely as the organ becomes distended. Tt has three folds, which are detached from the stomach and carried on to the adjacent parts, and which are formed in the manner indicated in the general description of the peritoneum. These folds constitute the cardiac ligament, the gastro-hepatic ligament or omentum, and the great omentum. The cardiac ligament is a short, serous band developed around the terminal extremity of the cesophagus, and strengthened by fibres of yellow fibrous tissue. It attaches the stomach to the posterior’ face of the diaphragm, and is continuous, on each side, with the two folds about to be described. The gastro-hepatic (or lesser) ligament is a band composed of two layers, which leave the lesser curvature of the stomach, and are inserted into the ior fissure of the liver. It is prolonged posteriorly, and to the right, along the duodenum, where it constitutes a peculiar serous frenum which will be studied with the small intestine. The great, or gastro-colic omentum, is detached from the whole extent of the great curvature, from the cardia to the pylorus, beyond which it extends to the duodenum. The portion surrounding the left cul-de-sac is excessively short, and is carried to the sublumbar wall of the abdomen, to which the stomach is fixed. For the remainder of its extent, this omentum is greatly developed, and hangs freely in the abdominal cavity, among the intestinal convolutions. The border opposed to the stomach is attached to the terminal portion of the large colon, and to the origin of the lesser colon. For further details, see the description of the peritoneum. These three ligaments fix the stomach in the abdominal cavity, in addition to the «esophagus and duodenum, which are continuous with it. . Muscular membrane.—This tunic, comprised between the serous and mucous layers, is lined internally by a covering of condensed connective tiseue which adheres intimately to it, and which may be regarded as the membrane of the stomach. Dissection shows this muscular tunic to be composed of three superposed planes. The superficial plane envelops all the right sac, and the majority of the fibres composing it are spread in loops around the left cul-de-sac, their extremities being lost on the surfaces of the organ. Some of them even extend over the great curvature, to the surface of the right sac; while others are evidently continuous with the superficial fibres of the cesophagus . 185, a). e middle plane (Fig. 185, 8) is formed of circular fibres spread over the whole of the organ. In the right sac, they are placed immediately below the serous membrane; in the left sac, they pass beneath the fibres of the superficial plane, and finish by becoming confounded so intimately with these, that towards the tuberosity formed by the left extremity it is impossible to distinguish them. By their aggregation around the pylorus, 380 THE DIGESTIVE APPARATUS IN MAMMALIA, they constitute the sphincter (or pyloric valve) which enyelops th orifice. nate The deep plane (Fig. 186, a), like the first, is specially destined for the left sac, and cannot be properly studied except in an ev stomach = deprived of its mucous membrane. Much thicker than the superficial plane, 2 it yet, in its general arrangement, much resembles it. ‘Thus, its icu A present loops which embrace the left cul-de-sac, and whose extremities are lost on the faces of the organ, where some of them become continuous with Fig. 185. A MUSCULAR FIBRES OF THE STOMACH ; DEEP AND MIDDLE MUSCULAR LAYERS EX- EXTERNAL AND MIDDLE LAYERS, POSED BY REMOVING THE MUCOUS MEM- A, Fibres of the external layer enveloping BRANE FROM AN EVERTED STOMACH, the left sac; B, Fibres of the middle plane _, Deep layer of fibres enveloping the left sac ; in the right sac; C, Fibres of the cso- B, Fibres of the middle sad which alone phagus, form the muscular layer of the right sac; "©, Fibres of the esophagus. 3 the circular fibres. The loops nearest the cesophagus embrace the stomachal __ opening of that canal like a cravat. It is to be remarked that the fibres of this deep layer intersect those of the superficial plane; the former passing from the left to the right sac, in inclining downwards towards the great curvature, while the latter are directed to the right and slightly upwards. 4 From this arrangement it results, as a glance at Figs. 185, 186 will show: 1, That the right sac has only a single muscular plane; 2, That, on the contrary, the left sac has three, all of which concur in propelling the aliment that has accumulated in the left or cesophageal compartment into the right, or true stomach. | 8. Mucous membrane.— Independently of the general characters notified in the interior of the stomach, it has to be remarked that the gastric mucous membrane is united to the preceding tunic by an expansion of connective tissue ; though it adheres but feebly throughout the right sac, especially towards the greater curvature, where it is thickest; and that it has no ridges in the left sac, though in the right they are always present, even when the organ is inflated. On the surface of this membrane are seen microscopical apertures (ones a the orifices of the excretory ducts of glands; these are rare in the left sac, THE STOMACH. 391 but extremely numerous in the right. In this region they are separated from each other by minute processes resembling papille; but the latter are only met in the vicinity of the pylorus. The gastric mucous membrane is composed of an epithelial layer and a corium, in which is distinguished a glandular and a muscular layer. The epithelium is stratified and tesselated in the left compartment, simple and cylindrical in the right sac, where it covers the little mueous processes that separate the glandule, and penetrates more or less deeply into the interior of these. In the left side there are found some glandular organs analogous to those of the cesophagus, but the real glandular layer belongs only to the Fig. 187. Fig. 188. moos PORTIONS OF ONE OF THE CA&CA MORE HIGHLY MAGNIFIED, AS SEEN LONGITUDI- * ' NALLY (A),, AND IN TRANSVERSE SEC- PEPTIC GASTRIC GLAND, “TION (B). a, Common trunk; 5, 6, Its chief branches; a, Basement membrane; 5, Large glandular c, c, Terminal ceca, with spheroidal gland- cell; c, Small epithelial cells surrounding cells, the cavity. right side. There are found multitudes of parallel tubular glands, united by a small quantity of delicate connective tissue which is very rich in nuclei. secrete the gastric fluid, or furnish the mucus that covers the surface of the epithelium ; they are consequently distinguished as pepsine (or peptic), and mucous glands, the former being much more numerous than the latter They are composed of a simple straight tube at their origin (exeretory duct), which frequently divides into two or more flexuous tubes that 392 THE DIGESTIVE APPARATUS IN MAMMALIA, terminate in culs-de-sac (or glandular ceca). The epithelium is not the same in the two kinds of glands: the mucous glands (Fig. 189, a, b) are lined with cylinder-epithelium throughout their extent ; Fig. ;190, the peptic glands (Figs. 187,188) are lined with Bias 0 AaORRG cylinder-epithelium at their origin (Fig. 187, a), but the secretory tubes contain round peptic cells. (Each ceca, when highly magnified, is found to consist of a delicate basement membrane (Fig. 188, a) inflected over a series of nearly globular cells (b), which occupy almost the whole cavity of the tube, and contain a finely-granular matter ; the narrow passage left vacant in the centre is, however, still surrounded by a layer of epithelial cells (c), whose small size is in striking contrast to the large dimensions of the gland cells.) The muscular layer (of the mucous membrane) is immediately beneath the glandular structure, and contains two planes of intersecting fibres. Lastly, the connective layer of the corium is thick and loose, sustains the vessels (and nerves), and unites the mucous to the muscular tunie of the stomach, ; 4, Vessels and nerves.—The stomach receives its blood by the two branches of the gastric artery, the splenic and its terminal branch—the left epiploic artery, and by the pyloric and right epiploic arteries. The principal arterial ramifications extend be- ring tape vm, tween the mucous and muscular layers, where eer wiun' aan’ they furnish two capillary reticulations to the a, Wide trunk; 6, b, Its cecal glandular layer: a deep network that surrounds appendage, the secretory tubes, and a superficial placed be- tween the alveoli. The blood is carried from the organ to the vena porte by the satellite venous branches. The lymphatics Fig. 190. ‘i z ae v Abe BEY an Aegis gh Seite A APPEARANCE OF THE PROPER GASTRIC MEMBRANE OF THE STOMACH IN AN INJECTED PREPARATION (HUMAN). A, From the convex surface of the folds or ruge; B, From the neighbourhood of the pylorus, where the orifices of the gastric follicles occupy the interspaces of the deepest portions of the vascular network. form a subserous and two deep networks at the base of the glandular layer and in the fibrous membrane. They enter small ganglia (or glands) situated along the ourvatures, and from these to Pecquet’s reservoir. The _ only a single sac, whose internal mucous THE STOMACH. 393 nerves are derived from the pneumogastrics and solar plexus, and in accom- -panying the vessels show microscopic ganglia in their course; their mode of termination is not known. Foncrions.—In the stomach is begun those transformations by which alimentary matters are rendered capable of being assimilated. There the food comes into contact with the gastric fluid, by whose action its principal elements, and particularly the albuminoid substances, become soluble and absorbable, after undergoing some isomeric changes, __DIPFERENTIAL CHARACTERS IN THE STOMACH OF OTHER THAN SOLIPED ANIMALS. The stomach is an organ that exhibits great differences in the various domesticated animals. In the study of tlese differences, we will proceed from the simple to the complex. 1, The Stomach of the Pig. The Pig's stomach is simple, like that of the Horse, but it is less curved on itself, and the ia is nearer the left extremity ; the latter has ulso a small conical dilatation, which has been compared to a cowl curved backwards. The cesophagus opens into the stomach by a wide infundibulum, an the mucous membrane of that conduit is prolonged over the gastric surface in a radius of from two to three inches around the cardia. Here again we find a “trace of the division into two sacs,” common to Solipeds. The capacity of the Pic’s stomach averages from one and a hulf to two gallons. (The muscular tunic is thicker in’ the right than the left extremity; near the cso- plagus the serous tunic shows some transverse folds.) 2. The Stomach of Carnivora. (Fig. 191.) In the Dog and Cut the ventriculus is but little curved, and is pear-shaped, the small extremity corresponding to the : pylorus. The cardia is dilated like a Fig. 191. unnel, and is nearer the left extremity of theorgan than in other animals, The cesophageal mucous membrane is not con- tinued the n of that orifice. The simple stomach of Carnivora forms membrane presents, throughout its whole extent, the same organisation as the membrane lining the right sue of Soli- peds. This membrane is remarkable for the regular and undulated folds it forms when the stomach is empty. Nothing is more variable than the capacity of the Doz’s stomach, because of the great dif- ferences in the size of this animal, accord- ing to breed. M. Colin has found the minimum to be 1} piuts, and the maxi- mum 1 8; he calculates the aver- see to be about 2} quarts. In the Cat, average is from 2 to 2} gills. 83. The Stomach of Ruminants. These animals are distinguised from the others by the ficulty they possess of swallowing their food after imperfect comminution, and causing it to return again into the mouth to submit it toa second mastication, previous to final de- glutition. The gastric apparatus is ad- STOMACH OF THE DOG, mirably arra: to effect this physio- A, Esophagus; B, Pylorus. logical finality, and is remarkable for its enormous development, as well as its division into four separate pouches, which are regarded as 80 many stomachs. 34 THE DIGESTIVE APPARATUS IN MAMMALIA, These cavities represent a considerable mass that fills the greater part of the abdominal cavity, and the medium capacity of which is not less than fifty-five gallons! __ One of them, the rumen, into which the csophagus is inserted, constitutes nine-tenths — of the total mass. The other three, the reticulum, omasum, und abomasum, form a short chain, continuous with the left and anterior portion of the ramen. The abomasum alone should be considered as a true stomach, analogous to that of the Dog, or the right sac of the ventriculum of Solipeds. The other three compartments only represent, like the left sac in the latter animals, cesophageal dilatations. The description about to be given of each of these divisions more particularly applies to the Ox ; care will be taken, in the proper place, to note the special peculiarities in the stomach of the Sheep and Goat. Rumen (Fig. 192).—This reservoir, vulgarly designated the paunch, alone occupies three-fourths of tle abdominal cavity, in which it affects a direction inclined from above to below, and from left to right. Fig. 192. / Se SS TNA A) ye ai i we 1)» NSS << re TNS N iN BA, UP uff FF STOMACH OF THE OX, SEEN ON ITS RIGHT UPPER FACE, THE ABOMASUM BEING DEPRESSED, A, Rumen, left hemisphere; B, Rumen, right hemisphere; c, Termination of the esophagus; D, Reticulum; £, Omasum; F, Abomasum. External conformation.—Elongated from before to behind, and depressed from above to below, it offers for study: 1, An inferior and a superior face, nearly plane, smooth, and divided into two lateral regions by traces of fissures, which are only sensible at the extremities of the organ; 2, A left and right border, smooth, thick, and rounded ; 3, A posterior extremity, divided by a deep notch into two lobes, described by Chabert by the name of conical cysts; 4, An anterior extremity, offering an analogous arrangement, and concealed, at first sight, by the stomachs (or compartments) superadded to the rumen; the notch on the right of this extremity divides it into two unequal pouches, which will be referred to presently. It is to be remarked that these two notches, which are prolonged on the surface by furrows that separate these into two lateral regions, divide the rumen into two sacs, a right aud left ; this division we will find more manifest in the interior of the viscus, The right sac, the shortest, is in great part enveloped by the serous covering whieh constitutes the tomentum. The left sac surpasses the other by its two extremities, except in the Sheep and Goat, in which the right conical cyst is longer. than the left. ‘The anterior extremity of this left sac is thrown backwards on the corresponding tt THE STOMACH. 395 lobe of the right sac; above, it receives the insertion of the cesophagus, and is continuous, in front, with the reticulum. Relations.—The external form of the rumen being determined, the study of its relations becomes easy. By its superior surface, it is in contact with the intestinal mass ; its opposite face rests on the inferior abdominal wall. Its left border, supporting the spleen, touches the most elevated part of the flank and the sublumbar region, to which it adheres by cellular tissue, as well as the vicinity of the coeliac trunk and the great mesenteric artery; the right border, margined by the abomasum, responds to the most declivitous portion of the right hypochondriac and flank, as well as to the intestinal circumyolutions. The anterior extremity, bounded by the reticulum and o advances close to the diaphragm; the posterior occupies the entrance to the pelvic cavity, where it is more or less in contact with the genito-urinary organs lodged there. In ln ca female, the uterus is prolonged forwards on the upper face of the viscus ribed. Interior (Fig. 193).—In the interior of the rumen are found incomplete septa, which repeat the division into two sacs already so marked externally. These septa are two in Fig. 193. INTERIOR OF THE STOMACH IN RUMINANTS; THE UPPER PLANE OF THE RUMEN AND RETICULUM, WITH THE (SOPHAGEAL FURROW, A, Left sac of the rumen; B, Anterior extremity of that sac turned back on the right sac; Cc, Its posterior extremity, or left conical cyst; G, Section of the anterior pillar of the rumen; g, g, Its two superior branches; H, Posterior pillar of the same; A, h, A, Its three inferior branches; 1, Cells of the reticulum; J, (Esophageal furrow ; K, Esophagus; L, Abomasum. number, and resent large muscular pillars, which correspond inferiorly to the notches described at the extremities of the organ. The anterior pillar (Fig. 193, @) sends to the inferior wall of the rumen a strong prolongation, directed backwards, and to the left; it is continued on the superior wall by two branches, which separate at an acute angle. The posterivr pillar (Fig. 193, H), more voluminous than the preceding, has three branches at each of its extremities—a middle and two lateral. The middle branches are carried forwards on the limit of the two sacs, which they separate from one another; that from above mects the corresponding branch from the anterior pillar, The 396 THE DIGESTIVE APPARATUS IN MAMMALIA, lateral branches diverge to the right and left indescribing a curve, and in cireumserib- ing the entrance to the conical cysts, which they transform into two com distinct from the middle portion of the sacs of the rumen; the inferior go to meet the superior branches, but do not altogether join them. The internal surface of the ramen is covered by a multitude of papillary prolongations, dependencies of the mucous membrane. To the right, and in the these papille are remarkable for their number, their enormous development, and their general foliated shape. On the left side they are more rare, particularly on the superior wall, and only form very small mammiform tubercles; they are absent on the muscular columns. This papillary arrangement is still more developed in certain wild Ruminants, and it is scarcely possible to give an idea of their richness in the stomach of the Gazelle. The interior of the rumen offers for study two openings, situated at the anterior extremity of the left sac: one is the cesophageal orific , pierced in the superior wall, dilated into an infundibulum, and prolonged into the small curvature of the reticulum by a particular furrow (or channel), which will be described after the latter compart- ment; the other, placed below, and opposite the preceding, traverses the bottom of the cul-de-sac from before to behind, and forms the communication between the paunch and reticulum: it is a very large opening, circumscribed below and on the sides by a septum or semilunar valve, resulting from the junction of the parietes of the rumen those of the reticulum. Structure.—Like all the hollow organs in the abdomen, the rumen has three tunics : a serous, a muscular, and a mucous. The serous envelops the organ throughout, except above, in front, and to the left, the point which touches the sublumbar region, and the pillars of the diaphragm, as well as the bottom of the notches which separate tlie culs-de-sac from the extremities. This membrane gives origin, like that of the stomach of the Horse, to a vast duplicature— the great omentum. ‘The arrangement of this, which is somewhat difficult to observe in the Ox, in consequence of the enormous weight of the gastric mass, is readily seen in the smaller Ruminants. It begins at the middle of the faces of the paunch and the fissure intermediate to the two conical cysts, forming a wide envelope that contains the right sac and the abomasum; it becomes attached in passing over the great curvature of the last-named cavity, and is confounded, superiorly and posteriorly, with the great mesentery. The muscular coat is very thick, and forms the internal columns of the viseus. Its fibres are disposed ijn several layers, whose fee ca is simple, and offers nothing really interesting to study, except in the points where the serous tunic passes from one cul-de-sac to another, or from the rumen to the reticulum; there it is often accompanied by thin and wide muscular fasciculi which, like the latter membrane, stretch over the intermediate fissures, and thus become real unitive or common fibres. The muscular fibres of the rumen present an unmistakable transverse striation—a very rare physical characteristic in the muscular tissue of organic life. The mucous membrane offers some peculiarities, which deserve a few words. The corium is very thick, and probably contains some glands, but they must be extremely few. The free face of the membrane is excessively uneven, in consequence of the papillary apparatus mentioned above. The papillz of the rumen are foliaceous, conical, or fungiform. Those of the first _ description are much more numerous than the others; they have the shape of an oval, elongated leaf, their summit is wide and rounded, and the base narrow and apparently implanted in the corium, On one face is a little rib that springs from the base and disappears on the widened bon resembling the principal vein or nervule of a leaf. On the other face, opposite the vein, is a faint longitudinal groove. These japille are constituted by a layer of nucleated connective tissue, covered by epithelium ; the former, in the principal papills, has on its faces and extremities minute prolongations, resembling on a small scale the secondury papille described as existing on the lingual mucous membrane. In the centre of the papille are one or two main arteries, derived from the network of the corium. These pass, in a slightly flexuous manner, to the summit, and break up into several branchlets, succeeded by veins, that descend along the surface of the papilla into each of its secondary prolongations. The conical and fungiform peatlin are few in the left sac, and resemble the papille of the same name described on the tongue. ‘Lhe epithelium of the mucous membrane of the rumen is remarkable for its stren and cohesiveness. It belongs to the category of stratified tesselated epithelium, and forms a sheath to each papilla, covering the corium in the interpapillary spaces. There are frequently found, in opening the rumen of animals just killed, large THE STOMACH. 397 exfoliated patches on the surface of this layer. This is a sufficient indication of the activity of the secretion of the epithelium, and the rapidity of its renovation. Reticvutum (Hoxeycoms) (Figs. 192, 193).—Situation—Form—Relations.—This, the ‘smallest compartment, is elongated from one side to the other, slightly curved on itself, and placed transversely between the posterior face of the diaphr in one directiun, and the anterior extremity of the left sac of the rumen in the other; the latter only ng, externally, to be a prolongation, or a diverticulum of the rumen. Tt has two faces, two curvatures, and two extremities, The anterior face adheres to the phrenic centre of the diaphragm by cellular tissue. The posterior face lies against the anterior extremity of the rumen. The great inferior or convex curvature oceupies the suprasternal region. The lesser, superior, or concave curvature partly responds to the lesser curvature of the omasum. The left extremity is only separated from the rumen by a fissure, which lodges the inferior artery of the reticulum. The right extremity forms a globular cul-de-sac, in relation with the base of the abomasum. - Interior (Fig. 193).—The internal surface of the reticulum is divided by ridges of the mucous membrane into polyhedral cells, which, in their regular arrangement, look like a honeycomb; tliey are widest and deepest in the cul-de-sac, and become gradually smaller in approaching the superior curvature. The interior of these cells is divided into smaller s included one withiu the other, by secondary and successively-decreas- ing septa. The principal septa offer on their free border a series of conical prolonga- tions, with a roug. hurd summit; while their faces are studded with minute, blunt, or pointed papille. The secondary septa a’so show similar prolongations; and those on their free margin are even more developed than on the chief septa. Lastly, from the bottom of the cells spring up a crowd of long, conical, and very pointed papill, resem- bling ona Sapte in their arrangement. It may be noted that the foreign bodies so frequently swallowed by Ruminants, are usually in the reticulum; therefore it is that at the bottum of the cells are foun! either small stones, and needles or pins, often fixed in the intermediate septa, or nails, seraps of iron, ete. ‘The interior of the reticulum communicates with the left sac of the rumen by the orifice already described, and with the omasum vd a particular open- ing, placed near the middle of the small curvature, though a little more to the right than the left.. This opening, eight or ten times te th than the preceding, is connected with the infundibulum of the cardia by a remarkable groove (or chanuel), the esophageal, which will be described separately, as it does not properly belong to the reticulum. Structure—The serous membrane does not cover all the anterior surface of the organ, as the latter adheres to the posterior face of the diaphragm. The muscular tunic is much thinner than that of the paunch, and more fasciculated. The fibres pass in the same direction. The corium of the mucous membrane sends a prolongation into each of the septa of the alveoli, and into each of the conical papillze on these septa, or to the bottom of these alveoli. The stratified pavement epithelium is very thick, and its horny layer is developed at the summit of the pill. fabreadeas Groove (Fig. 198). This gutter is so named because it appears to continue the cesophagus to the interior of the stomach. It extends on the lesser curvature of the reticulum from the cardia to the entrance of the omasum ; commencing in the rumen, it yn to the rceticulam for the remainder of its extent. Measuring from six to eight inches in length, this demi-canal is directed from above downwards, and from left to right, between two movable lips, which are fixed by their adherent border to the superior wall of the reticulum. Thes» two lips are thickened at their free which look downwards and to the left. At their origin at the cesophageal infundibulum, they are thin and but slightly elevated; but they become thick and salient on arriving near the orifice of the omasum, which orifice they surround, though neither meet nor become confounded with each other. mucous membrane covering these two lips is much corrugated outwardly and on the free border; but in tle interior of the groove it possesses all the characters of the er cag mucous membrane in being smooth, white, and ridged longitudinally ; near the of the omasum it has some large conical papille. If this membrane be removed to study the subjacent tissue, the following arrangement is observed: At the bottom of the channel, and in the space comprised between its two lips, are transverse muscular fibres, which belong to the rumen or reticulum, The lips themselves are entirely composed of longitudinal muscular fusciculi, particularly aban- dant towards the free border; these fusciculi are confounded with the proper fibres of the stomach towards the extremities of the canal, and are carried from one lip to the other in forming around the orifices which communicate by this canal. Omasum (Pealterium, Many-putes, MANY-LEAVES, or Mares Fig. 192).—In the 398 THE DIGESTIVE APPARATUS IN MAMMALIA, we ee . s Ox, this compartment is larger than the reticulum, but in the Sheep and Goat it: eo i smaller. -\, Situation—Form—Relations.—Situated above the cul-de-sac of the reticulum and the towards the pone a great curvature, turned upwards, and fixed in the posterior fissure of the liver “ee omental freenum which is continued on the lesser curvature of the abomasum and duodenum; a lesser curvature, which looks downwards and responds to = the reticulum ; a left extremity, exhibiting the neck, which corresponds to the orifiee of == communication between the reticulum and many-plies; a right extremity, continuous = with the base of the abomasum, from which it is separated by a constriction analogous to . that of the anterior extremity, but much less marked. | Interior —This compartment shows in its interior the two apertures placed at its extre- mities. The right orifice, opening into the abomasum, is much wider than the left,whieh = - Fig, 193. SECTION OF THE WALL OF THE OMASUM OF THE SHEEP; FROM THE GREAT CURVATURE, SHOWING THE ORIGIN OF THE LEAVES. p, Peritoneum; M, The two muscular layers; ©, Epithelium; 1, 1, Principal leaves at their origin; 2, Secondary leaf; 3, 3, Leaves of the third order; 4, Denticu- lated lamina; 5, 5, Two planes of muscular fibres ascending into the principal __ leaves, some issuing from the muscular layer of the organ. communicates with the reticulum. 'The cavity which these orifices bring into communiea- tion with the adjoining My anpomee offers one of the most curious arrangements met with in the viscera; it being filled by unequally-developed leaves of mucous membrane, which — follow the length of the cavity. These laminze have an adherent border attached either _ to the great curvature or to the faces of the organ, and a free concave border turned — towards the lesser curvature. They commence at the side of the orifice of the reticulum by denticulated ridges, between which are furrows, and which are prolonged from the base of the leaves to the entrance of the abomasum. At the latter a disappear altogether, after rapidly diminishing in height. Their faces are studded by a_ multitude of very hard mamillary papillw, resembling grains of millet, which are more ‘ developed and conical on some of the leaves than others. All these lamellar prolongations _ are far from being of the same extent; twelve to fifteen are so wide that their free border nearly reaches the lesser curvature of the viscus, and between these principal leaves are — others which, though regularly enough arranged, are more or less narrower. At first there is remarked a secondary leaf, half the width of the chief ones, between which it is placed; then, on each of its sides, another, one-half narrower ; and, lastly, at the base of these, two denticulated laminz more or less salient. In a general way, the lamine which are inserted into the great curvature are the longest and widest; und those attached to = the faces of the viseus become shorter and narrower as they draw nearer the lesser : curvature. The space comprised between these prolongations is always filled by attenuated alimentary matters, which are usually impregnated by a very small quantity of fluid, but are also often dry, and sometimes even h»rdened into compact flakes. THE STOMACH. j 399 Structure —The serous layer is a dependency of the peritoneum, and offers nothing _ particular; it does not completely cover the anterior face, The muscular tunic is much fasciculated, and thin. - The mucous membrane is remarkable for the thickness of its stratified pavement epithelium ; all the leaves are formed by two layers of this membrane, laid one against the % ; and as their structure is interesting, we will notice it. a. the ere leaves are composed of this duplicature of mucous membrane, and two layers of muscular fibres between ; these layers are opposite each other at the eommence- ment of the leaf, and separated by a transverse vessel; in the remainder of their extent they are apart by the vessels that pass towards the border of the leaf. Their fibres are deta from the surface of the muscular tunie and, at certain points, from its deep 4 = In the smaller leaves there appears to be only one layer of muscular fibres: on an leaves are various-sized papilla, the smallest of which are like a grain of millet, Fig. 195. Fig. 196. SECTION OF A LEAF OF THE OMASUM. LONGITUDINAL SECTION OF A LARGE PA- 1, 1, Muscular planes; v, vessel; 2, Epithe- PILLA FROM THE OMASUM,. SHOWING lium; 3, 3, Small-sized papille, round NERVE-CELLIS IN ITS INTERIOR, and hard. and have for base a mass of condensed connective tissue, whose superficial fibres form a kind of shell (Fig. 195); the largest are club-shaped. They receive blood-vessels, and ; we have found in the connective tissue, elements with a somewhat irregular outline, pro- vided with nuclei, which we considered to be nerve-cells (Fig. 196.) Apomasum (Reep or Renner. Figs. 192, 193).—Situation—Form—Relations—The abomasum stands next to the rumen for capacity. It is a pyriform reservoir, curved on | itself, elongated from before to behind, and situated behind the omasum, above the right ' sacofthe rumen. On the right it touches the diaphragm and the hypochondriac; on the left it is related to the rumen, The greater curvature, turned downwards, receives the insertion of the great omentum. The lesser curvature, inclined upwards, gives attachment to the serous band already noticed when speaking of the great curvature of the omasum. Its base is in contact with the cul-de-sac of the reticulum, and is separated from the omasum by the constriction in the form of a thick neck, which corresponds to the communicating orifice of the two stomach-. Its point, directed upwards and back- __- wards, is continued by the duodenum. Interior —This being the true stumach of Ruminants, the mucous membrane lining its interior acquires all the characters which distingnish that of the stomach of the Carnivora, or that of the right sac of the Horse’s stomach. It is soft, spongy, smooth to the touch, vascular, red-coloured, covered by a thin epithelium, and provided with numerous for the secretion of the gastric juice. Thinner than in monogastriec animals, this tenuity is compensated for by a much greater extent of surface, which is still further increased by numerous lamellar folds. These latter are analogous in con- stitution to those of the omasum, cross in a very oblique manner the great axis of the a m, and altogether affect a kind of spiral arrangement. The abomasum has two apertures: one, situated at its base, opens into the omasum ; the other, placed opposite to the first, and much narrower, is the pylorus, which is cireumseribed, as in the other animals, by a muscular ring. Structure —The serous membrane is continuous with the omenta which abut on the great and lesser curvatures of the viscus. The muscular layer is of the same thickness asin the omasum, The internal tunic has already been noticed. Fesorions oF tHe Stromacn ry Ruminants.—We cannot pretend to give here a of the phenomena of rumination, but must confine ourselves to describe in a few words what are the principal attributes of each gastric dilatation. i OG aaa 400 THE DIGESTIVE APPARATUS IN MAMMALIA, - * The rumen is a sac where the aliment taken ae feeding-time is kept in ve “ and whence it is again carried into the mouth during rumination, after having” cae more or less softened. "ae The reticulum participates in the functions of the ramen, to which it is only a kind of diverticulum. But it is particularly with regard to liquids that it plays the part ofa Spat hind the solid substances contained in it being always diluted by a large quantity of water. The esophageal groove carries into the omasum the substances swallowed a second perscio rumination, or even those which the animal ingests in very small quantity for the first time. 7s The omasum completes the trituration and attenuation of the food, by pressing it between its leaves. re The abomasum acts as a true stomach charged with the secretion of the gastrie juice ; in this reservoir occur the essential phenomena of gastric digestion. COMPARISON OF THE STOMACH OF MAN WITH THAT OF ANIMALS. In its form, the stomach of Man much resembles that of the Carnivora. » The insertion of the cesophagus, however, does not offer so large an infundibulum. The organ is situated in the Tet hypochondriac, and is nearly horizontal. Everywhere the mucous membrane is red and glandular; the muscular fibres are disposed in three planes, as in Solipeds; but the superficial and deep are particularly directed towards the left sac. ~ THE INTESTINES. (Figs. 204, 205, 206.) The alimentary canal is continued from the stomach, in the abdominal cavity, by a long tube doubled on itself a great number of times, and whieh terminates at the posterior opening of the digestive apparatus, This tube is the intestine. Narrow and uniform in diameter in its anterior portion, which is named the small intestine, it is irregularly dilated and sacculated in its posterior part, the large intestine. These two portions, so markedly defined in all the domesticated mammals, are but imperfectly distinguished from one another with regard to the digestive phenomena occurring in their interior. We will study them in all the animals which interest us, and conclude bya * general and comparative examination of the entire abdominal portion of the digestive canal, Preparat.on.—The study of the intestines does not demand, popedy: speaking, any special preparation; it being sufficient to incise the inferior wall of the abdomen to expose these vis-era. As their mass, however, is heavy and unmanageable, it is advirable to expel their contents in a manner similar to that recommended for the preparation of the stomach; a puncture at the point of the cecum allows the escape of the substances accumulated in that reservoir—those which fill the eee colon may be removed by an incision made towards the pelvic curvature, and those in the floating evlon by she rectum. The small intestine: may be evacuated by three or four openings at about equal distances in the length of the viscus. Having done this, inflate the intestines to somewhat of their natural volume; th’s preparation then perm'ts the —— arrangement of the intestinal mass in the interior uf the abdomen to be easily studied. : Le It would be well to remove the entire mass altogether from the body, and lay it out on a table, so as to isolate the various parts, study them in succession, and note their form. 1. The Small Intestine. (Vigs. 204, 205, 206.) Length—Diameter.—The small intestine is a long tube, which, in a Horse of ordinary height, may average about 24 yards in length, and from 1 to 13 inches in diameter. This diameter is susceptible of variation, — according to the state of contraction of the muscular tunic of the viscus, Form.—This tube is cylindrical, doubled on itself, and presents two eur- vatures: one convex, perfectly free; the other concave, called the small — curvature, which serves as a point of insertion to the mesentery that sustains Le THE INTESTINES. 401 the organ. Removed from the abdominal cavity, freed from the serous folds which suspend it, and distended by air or water, this disposition of the small intestine naturally causes it to twist in a spiral manner. Course and Relations.—The small intestine commences at the right cul- de-sac of the stomach, from which it is separated by the pyloric constriction. At its origin it presents a dilatation which, in form, closely simulates a small. whose curvatures are the inverse of those of the proper stomach. Placed at the posterior face of the liver, this expansion, or head, of the small intestine begins the narrower portion, which at first is directed forward, then bends suddenly backward : thus forming a loop investing the base of the cecum on the right side; then it is carried to the left in crossing, trans- versely, the sublumbar region, behind the great mesenteric artery; here it is joined to the origin of the floating colon by a very short serous frenum. It then reaches the left flank, where it is lodged, and where it forms numerous folds that are freely suspended in the abdominal cavity among the convolu- tions of the small colon. The terminal portion of this conduit, which is easily recognised by the greater thickness of its walls and its smaller diameter, disengages itself from these convolutions to return to the right, and opens into the concavity of the cecum, below, and a little tothe inside of, the point where the large colon has its commencement. In the language of the schools, this terminal portion is named the ileum ciiciv, to twist); the part which is suspended in the left flank, and which ‘orms the principal mass of the intestine, is designated the jejunum (jejunus, empty); and the curvature formed by this viscera at its origin, from the pylorus to the great mesenteric artery, is termed the duodenum (twelve fingers’ breadth). This classical division is, however, altogether arbitrary, and scarcely deserves to be retained, It would be better to divide the intestine into a Jized or duodenal, and a free or floating portion. Mode of attachment.—The small intestine is maintained in its position, at its extremities, by the stomach and the cecum. But its principal means of fixation consists in a vast peritoneal fold, which, from its use, is named the mesentery (pécov, évrepov). is serous layer presents a very narrow anterior part which sustains the duodenum, and fixes it in such a manner as to prevent its experiencing any considerable displacement. Continuous, in front, with the gastro-hepatic omentum, this portion of the mesentery is successively detached from the base of the liver, the inferior aspect of the right kidney, or even from the external contour of the base of the cecum, and, lastly, from the sublumbar region, to be soon confounded with the principal mesentery. This becomes wider as it approaches the cwcal extremity, and arises, as from a centre, from the outline of the great mesenteric artery, to spread in every direction, and is inserted into the small curvature of the floating portion of the viscus. The great length of this insertion causes it to become extended in a spiral or screw-like manner, around its point of origin, It may be remarked that the terminal extremity of the intestine is retained between the two serous layers of the mesentery, to a certain distance from its free border. This peritoneal fold consequently forms at this point, at the side opposite to its insertion into the intestinal tube, a particular frenum, which is observed to be carried to the anterior face of the cecum. Interior.—The interior of the cylindrical tube formed by the small intestine offers longitudinal folds, which are effaced by distention, except towards the origin of the duodenal portion. Those met with in this situation 2D 402 THE DIGESTIVE APPARATUS IN MAMMALIA. possess all the characters of the valvule conniventes (valves of Kerkring) of — Man ; they resist the effects of traction exercised on the intestinal membranes, and are formed by two mucous layers laid together, with a plentiful supply of connective tissue between them. The internal surface of the small. intestine also offers for study a mul- titude of villosities and glandular orifices, or follicles, which will be noticed hereafter. It communicates with the inner surface of the stomach by the pyloric orifice, and with that of the cecum by means of an opening which projects into the interior of that reservoir, like a tap into a barrel. This projection, which is not very marked, is formed by a circular mucous fold, strengthened externally by muscular fibres, and is named the ilio-cweeal valve or valvula Bauhini. Two additional orifices open on the surface of the small intestine in its duodenal portion, from 5 to 8 inches from the chee one is the orifice common to the biliary and principal pancreatic te other that of the accessory pancreatic duct. Srrucrure.—The wall of the small intestine, like that of the other hollow viscera in the abdominal cavity, is composed of three tunics : 1. Serous membrane.—This envelopes the organ everywhere, except at its — small curvature, which receives the insertion of the mesentery. 2. Muscular coat.—Covered internally by a layer of condensed connective tissue (which is sometimes designated as a fourth tunic) this middle mem- brane has two planes of fibres: one, superficial, is formed ‘of longitudinal fibres uniformly spread over the whole surface of the viscus; the other, deep-seated, is composed of circular fibres, which are a continuation of those of the pyloric ring. 3. Mucous membrane.—This tunic, extremely interesting to study, is soft, spongy, highly vascular, very delicate, and of a reddish-yellow colour. Its external face is loosely adherent to the muscular layer, and its free aspect exhibits the villi, and the glandular or follicular orifices already noticed. It comprises, in its structure, an epithelial covering, and a mucous derm or corium. The epithelial layer is formed by a single row of cylindrical (or columnar) cells, implanted, by their summit, on the surface of the derm, and lining the interior of the orifices which open on the inner face of the membrane. The base of these cells has an amorphous cushion, which, when they are all united, appears like a thin layer spread on the inner surface of the intestine. The mucous derm is thick and loose in its deeper portion, and is con- stituted by fasciculi of connective tissue mixed with elastic fibres, and lymphoid elements. On its free surface it exhibits villosities and depressions, which correspond to the glands. It has a muscular layer, whose unstriped fibres are arranged in a similar manner to those of the muscular coat of the intestine. Lastly, it contains follicles, and vascular and nervous reticulations. We will study each of these. The villi are the foliated or conical appendages which are found to be most developed in the shortest portions of the intestine. In Birds and the Carnivora they attain their maximum length; while in Ruminants they are in a rudimentary state, though, whatever may be their dimensions, they are always visible to the naked eye. Their number is considerable, and they have been justly compared to the pile of velvet. .In structure, they are formed of a small spongy mass of embryonic connective tissue, in the centre of which are one’ or more lymphatic (or lacteal) vessels, with a THE INTESTINES. 403 magnificent network of peripheral capillary blood-vessels; the whole being inelosed in a complete epithelial sheath. Fig. 197. A. VILLUS OF MAN, SHOWING THE BLOOD-VESSELS AND LACTEAIS.—B, VILLUS OF A SHEEP. The orifices opening on the intestinal mucous membrane belong either to Brunner’s (duodenal) glands, or to those of Lieberkiihn (simple follicles), Brunner’s glands form a continuous layer beneath the duodenal mucous mem- brane, In their organisation, these small granular bodies are exactly like the acini of the salivary glands; each acini pos- sesses an extremely short excretory duct, that passes through the mucous mem- brane. (These racemose glands secrete a clear alkaline mucus, which contains no formed elements, such as cells or nuclei.) The glands (or crypts mucose) of Lieberkiihn or Galeati are placed in the substance of the mucous membrane, and are distinguished by their microscopical dlimensions, their considerable number, and their tubular form, which has caused each of them to be compared to the finger of a glove; they are implanted perpen- PORTION OF ONE OF BRUSNER’S GLANDS. bo =z D 404 THE DIGESTIVE APPARATUS IN MAMMALIA. dicularly in the mucous membrane, and open on its free surface. They are found throughout the whole extent of the intestine, and are lined with columnar epithelium, The solitary glands (glandule solitarisze, or lenticular glands) are round, salient bodies, visible to the naked eye. They are somewhat rare in the small intestine, but are more abundant at the posterior portion of the large intestine. They are formed by a mass of lymphoid elements enveloped by some condensed fasciculi of connective tissue. Above them the mucous membrane is slightly umbilicated, and is destitute of villiand tubular glands, though these are arranged in a circle around the follicles, to form the corone tubulorum. (The solitary glands usually contain a cream-like secretion, which covers the villi on their free surface. ) Fig. 199. PERPENDICULAR SECTION THROUGH ONE OF PEYER’S PATCHES IN THE LOWER PART OF THE ILEUM OF THE SHEEP, a, a, Lacteal vessels in the villi; 6, 6, Superficial layer of the lacteal vessels (rete angustum); c, c, Deep layer of the lacteals (rete amplum); d, d, Efferent vessels provided with valves; e, Lieberkiihn’s glands; f, Peyer’s glands; g, Circular muscular layer of the wall of intestine ; 2, Longitudinal layer ; ¢, Peritoneal layer, The aggregated follicles (glandulse ayminate) are nothing more than solitary glands collected together in a limited space, where they constitute what are known as the glands of Peyer or of Pecklin, or the honeycomb glands. Absent in the duodenum, and even at the commencement of the jejunum, these glands, about a hundred in number, are very irregularly placed on the internal surface of the intestine at its great curvature, on the side opposite to the mesentery. Their form is oval or circular, and the THE INTESTINES. 405 smallest scarcely measure more than some few hundredths of an inch square ; while the diameter of the largest increases to 14 inch. (Each of these patches is composed of a group of small, round, whitish vesicles, covered with mucous membrane; these vesicles consist of a Fig. 200, PERPENDICULAR SECTION THROUGH THE INTESTINAL WALL TO SHOW A SOLITARY FOLLICLE. a, Lieberkiihnian glands; 6, Solitary follicle; c, Lacteal vessels surrounding, but not penetrating, the follicles; d, Large efferent vessels, provided with valves. moderately-thick external capsule, having no excretory canal, and containing a similar secretion to that in the solitary follicles. by a zone or band of simple follicles, and the spaces between them are covered with villi. The vesicles are usually closed; though it is supposed they open at intervals to discharge their secretion. The mucous and submucous coats of the intestine are intimately adherent and highly vascular, oppo- site the Peyerian glands.) 4. Vessels and nerves.—The small intestine receives its arteries almost exclusively from the great mesenteric artery. One, which goes to the duodenum, comes from the celiac trunk. These arteries form a submucous network, from which branches pass inwards and outwards, the first to the muscular and serous tunics, the second to the glands and the villi. A tubular network sur- rounds each Lieberkiihnian gland, and is observed in each villus; while a spherical reticulation sur- They are surrounded Fig. 201. ‘” a - —— Ui PPS BN Ww rounds each solitary follicle, loops being given off VII OF INTESTINE, Wwrrit which penetrate nearly to the centre of the follicle. THEIR CAPILLARY PLEXUS INJECTED. The veins have the same arrangement, and finally enter the vena porte. 406 THE DIGESTIVE APPARATUS IN MAMMALIA, can The /ymphatics constitute three superposed networks in the mucous = membrane. The first is situated around the glandular orifices ; it receives Fig. 202. tiny a, Yi s 4 ; VA NY LZ oP “a + ee w/e BR a Bat i _A VP NpY SSS! a Vos ~ . » mM a ee | | 4 “| x 4 4 HORIZONTAL SECTION THROUGH THE MIDDLE PLANE OF THREE PEYERIAN GLANDS, SHOWING THE DISTRIBUTION OF THE BLOOD-VESSELS IN THEIR INTERIOR. ; the central lacteal from each villus; the second is placed between the glandular and the muscular layer of the mucous membrane ; finally, the third exists in the . portion of the membrane, and communicates with the meshes encircling the closed follicles, “The most voluminous emergent vessels pass through the wall of the intestine and accompany the blood- vessels between the layers of the mesentery, enter- ing the mesenteric glands, and terminating in the reservoir of Pecquet (receptaculum chyli). The nerves are from the solar plexus; they form a submucous reticulation and a myenteric plexus, comprised between the two planes of the muscular tunic. Microscopic ganglia are found on their course, Drvetorment.—The small intestine -shows it- DIAGRAMMATIC REPRESENTA- golf at an early period in the foetus, and during eure Betis say Dog i the foctal existence of Ruminants preserves a very 6, Contesl’ lecten); , Counec- remarkable predominance over the large intestine : tive-tissue corpuscles with ® predominance equally marked in the vessels it communicating branches; receives, for, in a foetus of five months, we have ¢, Ciliated columuar epithe- found the collective arteries of the small intes- peli 2 jeprroi sm “i. tine equivalent to about ten times the volume of rectly contiguous with the those of the caecum and colon. ; connective tissue corpuscles, Funorions.—It is in this tube, and under the i ee al THE INTESTINES. 407 ‘influence of the hepatic, pancreatic, and intestinal secretions, that are carried on those molecular transformations which properly constitute the digestive function, It is also in this intestine that the absorption of the nutritive principles and fluids commences, and in which the villi are the essential organs. 2. The Large Intestine. The large intestine commences by a vast reservoir in the form of a cul- de-sac, named the cecum. It is continued by the colon, whose posterior extremity is succeeded by the rectum. It is separated from the small intestine by the ileo-cecal valve. A. Caecum. (Figs. 204, 205, 206.) Situation —Direction.—This is a very wide and elongated sac, occupying the right hypochondriac, where it affects an oblique direction downwards and backwards. Dimensions—Capacity.—Its length is ordinarily a little over three feet, _ and it will contain, on an average, about 74 gallons of fluid. Form— External surface.—The elongated sac formed by the cecum is conical in shape, terminating in a point inferiorly, and bulging and curved like a crook superiorly. Externally, it exhibits a great number of circular furrows, interrupted by longitudinal muscular bands, four of which are observed in the middle portion of the organ; they disappear towards its extremities. The bottom of these furrows necessarily corresponds to the internal ridges, and these can be made to disappear by destroying the longitudinal bands, which considerably lengthens the cecum ; thus showing that these transverse puckerings are due to the presence of the riband-like cords, and have for their object the shortening of the intestine without diminishing the extent of its surface. Relations.—To study its relations, the cecum is divided into three ons : 1. The superior extremity, base, arch, or still better, the crook, presents in the concavity of its curvature, which is turned forwards, the insertion of the small intestine and origin of the colon. Placed in the sublumbar region, it résponds, superiorly, to the right kidney and to the pancreas, through the medium of an abundant supply of connective tissue. Outwardly, it touches the parietes of the right flank, and is encircled by the duodenum. On the inner side, it adheres by cellular tissue to the termination of the large colon, and is in contact with the convolutions of the small intestine. 2. The middle portion (meso-cecum) is in contact, inwardly, with the same convolutions and the large colon; outwardly, with the cartilages of the false ribs, whose curvature it follows. . 3. The inferior extremity, or point, usually rests on the abdominal pro- longation of the sternum; but as it is free and can move about in every direction, it often happens that it is displaced from this situation. Mode of attachment.—The cecum is fixed to the sublumbar region and the terminal extremity of the large colon by a wide adherent surface. All around this surface the peritonenm, which constitutes the serous covering of the cecum, is gathered into folds, and in passing from the eexeum to the origin of the colon, this tunic forms a particular short and narrow frenum designated the meso-ccecum. 408 THE DIGESTIVE APPARATUS IN MAMMALIA, Interior.—Viewed internally, the cecum offers for study the valvule or transverse ridges corresponding to the external furrows. We have already seen that these are due to simple cireular folds, comprising in their thick- ness the three tunics of the organ, and that they are susceptible of being effaced by distention, to re-appear afterwards in varying number and position ; differing widely, in this respect, from the valvule conniventes of the small intestine. Two orifices, placed one above the other, open on the internal surface of the cecum, at the point corresponding to the concavity of the crook. The Fig. 204, GENERAL VIEW OF THE INTESTINES OF THE HORSE; SEEN FROM THE RIGHT SIDE, WITH THE PELVIC CURVATURE AND A PORTION OF THE SMALL INTESTINE CARRIED BEYOND THE ABDOMINAL CAVITY. a, Esophagus ; b, Right sac of the stomach; ¢, Small intestine, showing its origin, or duodenal portion encircling the base of the cwcum; d, Caecum ; e, Origin of the large colon; f, First portion of the large colon; g, Suprasternal flexure; A, Second portion of the large colon; 7, Pelvic flexure; j, Third portion of the large colon; 4, Diaphragmatic flexure ; 7, Fourth portion of the large colon; m, Ter- mination of the free colon; n, Rectum; 0, Mesentery proper; p, Colic mesentery (meso-colon); 7, Neck of the vaginal canal; s, Spermatic vessels; ¢, Deferent canal; u, Bladder; v, Vesicule seminales; x, Pelvic enlargement of the deferent canal; y, Prostate; z, Suspensory ligament of the penis. most inferior represents the terminal opening of the small intestine at the centre of the ilio-cecal valve, whose presence in the domesticated animals has, in consequence of a wrong appreciation of analogies, been denied; it is nothing more than the projection described as being made by the end of the small intestine. The second opening, placed ebout 14 or 2 inches above the preceding, and puckered around its margin, establishes a communication between this viscus and the colon. If this opening be compared with the capacity of the canal which begins from it, it will be remarked that it could scarcely be narrower. aie, A, The duodenum as it passes behind the great mesen- tric 3; B, Free por- tion of the small intes- tine; C, Ileocecal portion ; D, Cxcum; E, F, G, Loop formed by the large colon ; G, Pelvic flexure; F, F, Point where the colic loop is doubled to constitute the suprasternal and dia- phragmatic flexures, THE INTESTINES. Fig. 205, G 409 Sel GENERAL VIEW OF THE HORSE'S INTESTINES; THE ANIMAL IS PLACED ON ITS BACK, AND THE INTESTINAL MASS SPREAD OUT. 410 THE DIGESTIVE APPARATUS IN MAMMALIA, Srructrore.—The serous tunic does not call for any notice beyond that already given when speaking of the attachments proper to the cecum. The muscular tunic is formed of circular fibres, crossed externally by longitudinal bands, which maintain the organ in transverse folds. The mucous membrane is thicker than that of the small intestine, and is also distinguished from it by the absence of the Brunnerian and aggregated glands. It has, however, the solitary follicles and crypts of Lieberkiihn, as well as some few intestinal villi. The blood-vessels are the cacal arteries and veins. The lymphatics pass to the sublumbar receptacle; and the nerves are derived from the great mesenteric plexus. Funcrions.—The cecum serves as a reservoir for the enormous quantities of fluid ingested by herbivorous animals, The greater part of this fluid, in its rapid passage through the stomach and small intestine, escapes the absorbent action of the villi and accumulates in the cecum, where it may be said to wash the alimentary mass with which it comes in contact; thus dissolving the soluble and assimilable matters this mass may yet contain, and favouring their entrance into the circulation through the immense absorbing surface formed by the mucous membrane of the large intestine. It does not appear that the aliment is submitted in the cecum to any transformation, all the molecular changes of the digestive process, properly speaking, having been accomplished when the mass reached the interior of this viscus. B. Colon. The colon is divided into two portions, which differ from each other in Fig. 206. THE COLON OF THE HORSE. 1, First portion ascending to form the suprasternal flexure; 2, Second portion descending to form the pelvic flexure, 7; 3, 6, Longitudinal muscular bands; 4, Point of the cecum, 5; 8, Duodenum; 9, Small intestine. volume, and in the disposition they affect in the abdominal cavity. The first is the large or double colon ; the second, the small or floating colon. Tue Laree or Dovsix Coron (Figs. 204, 205, 206).—This intestine THE INTESTINES. 411 begins at the cecum, and terminates by suddenly contracting at the origin of the small colon. _ Length—Capacity—It is from about 10 to 13 feet in length, and has a medium capacity equal to 18 gallons. Form—General disposition Removed from the abdominal cavity, and extended on a table or on the ground, this portion of the intestine appears as a voluminous canal, offering a succession of dilatations and contractions; its surface being traversed by longitudinal bands, and sacculated and furrowed transversely for a great part of its extent, exactly like the cecum. Tt is also doubled in such a manner as to form a loop, whose two branches are of equal length and are held together by the peritoneum, which is ‘carried from one to the other; so that the terminal extremity of the large colon returns towards the point of its origin. But this colic flexure, owing to its length, could not be contained in the abdomen ; and it is therefore doubled in its turn from above to below and from right to left (at the points Fr, r, in Fig. 205) SNe and forms curvatures which will be noticed pre- ig. 207. ‘sently. From this circumstance, it happens that the large colon, studied in the abdominal cavity, is divided into four portions lying beside each other in pairs ; so that a transverse section of that -eayity, made in front of the base of the cecum, would give for this intestine the results indicated in the annexed figure. Course and Relations.—In following the course of the large colon from its origin to its termina- tion, in order to study its four portions in their normal relations, the following is observed : ' Commencing from the arch of the cecum, the colon is directed forwards, ‘above the middle portion of that reservoir, which it follows to its point. Arrived at the posterior face of the diaphragm at its most declivitous part, it bends downwards and to the left, forming its first or suprasternal flexure, ‘because it rests on the xiphoid cartilage of the sternum (Fig. 204, g). Here begins the second portion of the viscus, which is in immediate contact with the inferior abdominal wall, and extends backwards into the pelvic cavity, where it is inflected to the left to constitute the pelvic flexure. This curvature, the centre of the colic loop, responds to the rectum and bladder, as well as to the deferent canals, or the uterus and ovaries, according to ‘the sex. It is succeeded by the third portion of the colon, which is carried ‘forward, above, and to the left of the preceding. Bound to the second division by peritoneum and connective tissue, this new section reaches the phrenic centre, and is then doubled upwards and to the right. The flexure arising from this third duplicature is called the diaphragmatic, because of its relations with the musculo-aponeurotic membrane which partitions the great cavity of the trunk, or the gastro-hepatic curvature, in consequence of its lying ually against the liver and stomach (it is also designated the sigmoid flexure) (Fig. 204, k). To this flexure succeeds the fourth and last portion of the large colon, bound to the first portion, as the second is to the third. This extends, posteriorly, to the base of the cmcum, where it terminates in a sudden contraction, and is continued by the small colon; it oceupies the sublumbar region, and through the medium of a cellular layer is applied against the inferior face of the pancreas and the inner side of the cwecal arch. Mode of attachment—The large colon can be easily displaced in the PLAN OF THE COLON, 412 THE DIGESTIVE APPARATUS IN MAMMALIA, abdominal cavity. It is nevertheless fixed: 1, By its origin, to the . and to the serous frenum which attaches it to that receptacle; 2, By the adherence of its terminal portion to the pancreas and the cross of the caecum ; 3, By the mesocolon, The latter ligament forms, in the concavity of the pelvic flexure a kind of racket, the handle of which is prolonged to a short distance between the two branches of the colic flexure. Beyond this, these two branches are directly placed side by side. External surface.—We have seen that the large colon deeeines offer the same diameter everywhere, and that it is bosselated, plicated, and traversed by longitudinal bands; it is, however, important to study in detail this dis- position of its external surface in each of the regions already named. At its origin, the large colon is extremely narrow, and scarcely equal to the small intestine. But it soon dilates and assumes a considerable volume, which it preserves beyond the pelvic flexure. It then becomes progressively constricted to the middle of its third portion, where the diameter, reduced to its minimum, is yet much greater than at the origin of the first portion. Near the diaphragmatic flexure, the large colon is again gradually dilated, and finishes by acquiring, near its termination, the greatest volume it has— yet exhibited. The muscular bands which maintain its transverse folds throughout the whole extent of its first dilated portion, are four in number. Three disappear in arriving towards the pelvic curvature, and the only one remaining is that which is placed in the concavity of that curvature. At the second dilatation there are three bands, two of which are prolonged to the floating colon. The .transverse folds formed by these flat bands are but faintly marked towards the pelvic curvature, and are altogether absent in the narrow portion succeeding it; it is only in the whole extent of the first dilatation that they are deepest and most numerous. Internal surface.—This is exactly like that of the cecum. Structure.—The serous membrane enyelops the whole organ, except in those places where it comes in contact with itself or with other viscera. So it happens that the peritoneum, in passing from the sublumbar region to the last portion of the colon, does not cover the surface which adheres by cellular tissue to the inferior aspect of the pancreas and cecum; neither, in being carried from one branch of the colic flexure to the other, does it envelop their opposed sides, except at the pelvic flexure, where it forms the meso- colon. The muscular tunic does not differ in its arrangement from that of the cecum; neither does the mucous membrane. The arteries emanate from the great mesenteric ; they are the two colic arteries. The two satellite veins soon forma single trunk, which enters the vena porte. The lymphatics empty themselves into Pecquet’ s reservoir. The nerves emerge from the great mesenteric plexus. Tue Smax1, or Fioatine Coron (Fig. 204).—This is a bosselated tube, which succeeds the large colon, and is terminated in the pelvic cavity by the rectum, Length— Form— Course—Relations.—This tube is about 10 feet in 1 and offers a disposition analogous to that of the small intestine, except it is double the size of that viscus, is regularly bosselated on its surface, and is provided with two wide and thick longitudinal bands, one on the side of its great, the other on its small, flexure. Arising from the terminal extremity of the large colon, to the ‘left of the cecum, where it responds to the termination of the duodenum, and where it receives the insertion of the great omentum, this intestine is lodged in the left flank, forming folds which - A ) : =o THE INTESTINES, 413 are mixed with the convolutions of the small intestine. It afterwards passes into the pelvic cavity, to be directly continued by the rectum, Mode of attachment.—¥ \oating like the small intestine, the small colon is suspended by a serous layer, exactly similar to the mesentery proper, though wider, and named the colic mesentery. This mesentery is detached from the sublumbar region, not from around a central point, but from a line extending from the great mesenteric artery to the bottom of the pelvic cavity. It is narrower at its extremities than in its central portion. _ Interior.—The internal surface of the floating colon shows valvular folds, analogous to those of the cecum and large colon. It is in the intervals between these that the fecal matters are moulded into balls. Structure.—The serous membrane is without special interest, and the muscular tunic is similar to that of the large colon. The mucous mewbrane is also the same. These membranes receive their blood by the small, and a branch of the great, mesenteric artery. A venous trunk, passing between the layers of peritoneum composing tle mesentery, carries back the blood to the vena portw. The lymphatics are nearly as fine and as numerous as those of the small intestine; they enter the same confluent, the reservoir of Pecquet. Founetions or tHe Cotcn.—In this intestine is accomplished the ab- sorption of fluids, and of soluble alible matters. When the alimentary mass arrives in the small colon, deprived of its assimilable principles and with excretory substances thrown out on the surface of the intes- tinal tube, it loses its name and receives that of excrement or faces. These excrements, compressed by the peristaltic contractions of the muscular tunic, are divided into little rounded or oval masses, which find their way to the rectum, where they accumulate, and whence, in due course, they are expelled. C. Rectum. (Fig. 204.) The rectum extends, in a straight line, from the entrance to the pelvic cavity to the posterior opening of the digestive canal, or anus. It is no- thing more, properly speaking, than the extremity of the small colon, the limit which separates them being somewhat arbitrary; it differs from that viscus, however, in having rio ridges, and in its walls being thicker and more dilatable, so that it can be distended into an elongated pouch, and form a reservoir or receptacle for the excrementitious matters until they are expelled. Relatims.—\t responds, superiorly, to the roof formed by the os sacrum ; inferiorly, to the bladder, the deferent canals, vesicule seminales, prostate gland, Cowper’s glands, or to the vagina and uterus; laterally, to the sides of the*pelvis. Mode of attachment.—There ought to be considered as such: 1, The page extremity of the colic mesentery, representing the mesorectum ; An orbicular fold, constituted by the peritoneum in its circular reflection around this viscera at the extremity of the pelvic cavity; 3, The suspensory ligaments of the penis, which, joining under the rectum, form a ring en- circling the posterior extremity of the intestine (see Fig. 204 and the description of the penis); 4, A thick, triangular fasciculus, comprising two lateral parts, and composed of white muscular fibres ; this fasciculus, which is really a prolongation of the muscular tunic of the viscera, is detached from the rectum above the anus, and is attached. to the inferior aspect of the coccygeal bones, between the inferior sacro-coccygeal muscles, where its outline can be seen beneath the skin when the tail is elevated. — . os 414 THE DIGESTIVE APPARATUS IN MAMMALIA, Sraveture.-The serous membrane does not envelop the whole of the — organ ; that portion which traverses the bottom of the pelvic cavity being left uncovered by it. The muscular layer is very thick, and com | as of large, longitudinal, and slightly spiral fasciculi, beneath which are annular fibres. The mucous membrane, loosely attached to the muscular tunic, shows longitudinal and transverse rugse. The small mesenteric and the internal pudic artery (artery of the bulb) supply these membranes with blood. The nerves are derived from the pelvic or hypogastric plexus. : Awnvus.—The anus, or posterior opening of the digestive tube, is situated at the posterior extremity of the rectum, under the base of the tail, where, in Solipeds, it can be seen forming a rounded prominence which diminishes with age. It is the border or margin of this orifice, which is corrugated like the mouth of a draw-purse, where the intestinal mucous membrane meets with, and is continued by, the external skin. In proceeding from within outwards, there are found the following elements entering into the structure of the anus : 1, The mucous membrane of the rectum; 2, The prolongation of the circular and longitudinal fibres of the muscular layer, forming what is named. the internal sphincter ;_ 3, A sphincter muscle, composed of red fibres, which receives the insertion © a retractor; 4, The fine, hairless, and closely-attached skin, which covers the sphincter ; though destitute of hair, it is rich in sebaceous follicles. We will only notice the muscles. : The SPHINCTER OF THE ANUS, emcpui ani) is formed of circular fibres, some of which are fixed above, under the base of the tail, and are confounded, below, with the muscles of the perineal region. Comprised between the skin and the prolongation of the muscular layer of the rectum, this muscle is (during life) in a state of almost permanent contraction to keep the anal aperture closed, it being only relaxed during the expulsion of fecal matters. The RETRACTOR OF THE ANUS, Or ISCHIO-ANAL muscle (retractor ani), is a wide band attached to the internal surface of the ischiatic ligament (sacro- ischiatic), and even to the supercotyloid crest, by aponeurotic fibres. The fasciculi composing this band are all parallel to each other, while their posterior extremities are insinuated beneath the sphincter, and are confounded with its fibres. This arrangement of the retractor ani clearly indicates that it pulls the anus forwards, re-establishing it in its normal position after expulsion of the feces : an act which always results in carrying the posterior extremity of the rectum backwards. These two muscles are of a red colour, and belong to those of animal life. Their vessels are derived from the same sources as those of the rectum. The hemorrhoidal nerve supplies them both with filaments, DIFFERENTIAL CHARACTERS OF THE INTESTINES IN OTHER THAN SOLIPED ANIMALS, In the domesticated animals, the intestines vary as much in their dimensions, length, and diameter, as in their general disposition. 1, The Intestines of Ruminants. (Fig. 208.) The small intestine of the Ox floats at the extremity of a broad mesenteric lamina, which is narrower in front than behind, plane throughout, except at its intestinal border, which is of considerable length, and is folded into a multitude of festoons. Twice the length of the small intestine of the Horse—averaging about 49 yards—it is about one-half its diameter. The duodenum, at first sustained by the omentum, which attaches the small curvature of the fourth compartment of the stomach to the posterior fissure of the liver, forms a particular loop, which is in contact with the sublumbar region before it goes to be suspended by the large mesentery, and to be continued by the convolutions of the floating portion. The ileum terminates as in the Horse, The ed Fees | ee | “ -< —h THE INTESTINES. 415 Peyerian glands are less numerous on the internal surface of the small intestine than in s, though they are larger in size. In the and Goat, they are often more than eight inches in length, and extend to Bauhin’s (ileo- cwcal) valve. - cxeum is nearly cylindrical in form, without bulges or longitudinal bands. The extremity of the cul-de-sac, rounded and globular, floats freely in the abdominal cavity, an is directed backwards. At its opposite extremity, the cwcum is continued directly with the colon, without forming a crook, after having received the insertion of the 1 _ In the Oz, in the vicinity of this insertion, there are traces of one of Peyer’s patches. In the Sheep and Goat, these patches are very numerous. The colon, sustained between the layers of the great mesentery, on the margin of which is suspended the small intestine, is rolled upon itself in such a way as to form a certain number of elliptical convolutions, by at first making several concentric spiral tarns, which leave a certain interval between them for the reception of the excentrie convo- lutions. The last spiral turn isa little distant from the others; in the smaller Ruminants, Fig. 208, GENERAL VIEW OF THE INTESTINES OF THE OX; RIGHT FACE. A, Origin of the duodenum ; B, Floating portion of the small intestine; c, Termina- tion of the small intestine; Dp, Cacum; £, Its point directed backwards; F, Flexure of the large colon at its termination; G, H, Terminal portion of the intestine.—1, Insertion of the ductus choledochus; 2, Insertion of the pancreatic duct. it is close to the insertion of the mesentery in the small intestine, which it follows to near the duodenum in describing regular festoons. On reaching the trunk of the great mesenteric artery, this convolution passes to the right, and is directed backwards, then forwards, thus forming a flexure, and turns back in company with the duodenal flexure. The colon then continues in a direct line to the rectum, attached to a short mesenteric layer, which, by its position, resembles the large suspensory band of the floating colon in Solipeds. The calibre of this intestine is at first equal to that of the cecum ; but it soon becomes constricted, and maintains a uniform diameter, which searcely exceeds that of the small intestine of the Horse. The muscular layer has the same arrangement as in the latter, although it is not covered in all its points by the serous tunic, in consequence of the situation of the colon between the two layers of the mesentery. In emaciated animals, however, it may be remarked that the serous covering furnished by these layers to the muscular coat of the colon is more extensive than at first we might be led to think; on the left side, the prominences of the spiral convolutivns are found to stand in relief on the surface of the mesentery, and it is therefore more completely enveloped in the correspondin itoneal layer. From this } ase tion, it will be seen that in the large intestine of Ruminants the excal division is well defined, but that the division of the colon into a large or double, and a small or floating ion can searcely be made; unless we regard as the large or flexure colon the spiral folds contained between the layers of mesentery, and see the float- ins portion in the posterior extremity of the tube lying at first against the sublumbar wall £16 THE DIGESTIVE APPARATUS IN MAMMALIA, of the abdomen, and afterwards suspended by the short mesenteric frenum resembles the great colic mesentery of Solipeds. It is worthy of remark that the Fig. 209. INTESTINES OF THE DOG, a, Stomach ; 6, Duodenum; ec, Jejunum ; d, Ileum 3. ¢ Cecum; f, Ascending colon; g, Transverse colon; A, Origin of des- cending colon ; i, Great omentum ; , Spleen ; /, Mesentery ; m, Pancreas.—1, Aorta; 2, Great mesenteric artery ; 3, Artery of the duodenum; 4, Artery of the large intestine ; 5, Small mesenteric artery. sin N : . a fl j . 7 | rea a 7 r be te ie Sy .. =) — oe = . mesenteric artery goes to first, and the small teric to the second as in the Horse. Measured whole extent, from the cul-de-sac to the an large intestine of the from 33 to 394 feet. therefore, longer than of the Horse; but its capa- oe SeeEE Fry. city is much less, for it does not exceed from 6} to 7} gallons. 2. The Intestines of the Pig. The average length of the P%q’s intestines is 72 feet, of which 56 go to the small, and 16 to the tween the layers of the me- sentery, it being, for the remainder of its extent, out- side that membrane, where it forms a distinct mass. Among the peculiarities of the small intestine, may be cited the presence of an immense Peyerian gland, which occupies the latter portion of the canal, where it figures as a band measur- ing from 5 to 6 feet in length. The caecum shows, on its internal surface, some Peye- rivn patches; it is bosselated, as in the Horse, and is fur- nished with three longitu- dinal bands, The colon has two of these pe yrei —— in a portion of its track, ove theres towards the cm- cum ; as well as sume trans- verse fulds. It is doubled exactly as in the Ox. 3. The Intestines in Car- nivora. (Fig. 209.) The intestines of the Carnivora are remarkable for their shortness and small volume. In a Dog of ordi- nary size, they scarcely measure more than 14 feet in length, of which only 24 to 28 rf de for The teres tateatina. In the Cat, the latter is about one-half this le and the entire extent of the viscus is equa to about 6 or 7 fcet. With re to Hi oe, THE INTESTINES. | 417 ‘ pac oeengw? ves the following averages: for the Dog’s small intestine, 1 quart ; fat, trifle more ee ree ss ocanoely | than the small intestine, and is neither sacculated nor urnished itudinal bands. In its short course, it is disposed somewhat like the ntes ; and,as in him, it may be divided into the ascending (Fig. 209, f), transverse (gq), and descending colon (h), which is continued directly with the rectum. _ Near the anus, this latter viscus presents on its sides two narrow apertures ape >t gga pouches, which are filled with a brownish matter, that has a strong iour, and which is secreted by the glands covering the internal wall of these - -_ QMfeasurements of the intes- tines, always a subject of interest _ to comparative anatomists, have es mage made by different authorities, Leyh gives the length of the Horse’s intestines as from ‘10 to 12 times that of its body ; + Oe fies as ti oe cee times; the and Goat from my: $2 Os thor are 150 fort, 120 being large ; in Sheep they 90 feet, 65 to 70 being small intestine; 18 for the large; large-sized gs averaged from 23 to 27 feet, to 22 of which were for the all intestine; small dogs had only 6 feet in many instances. The Cat has from 4 to 5 feet.) “ot THE HUMAN INTESTINES AND SUPERIOR MESENTERIC COMPARISON OF THE INTESTINES OF ARTERY. _ MAN WITH THOSE OF ANIMALS. 1], Descending portion of the duodenum ; 2, Transverse a, unfrequentl ama rtion; 3, Pancreas; 4, Jejunum; 5, Heum; 6, pig a of —s fore oe iam and appendix vermiformis; 7, Ascending duodenum and small intestine colon; 8, Transverse colon; 9, Descending colon ; er. The duodenum is from 10, Superior mesenteric artery; 11, Colica media; ; ‘Ti inches; is dilated at its 12, The branch that inosculates with the colica ‘origin. and firmly attached tothe ‘sinistra; 13, Pancreatico-duodenalis inferior; 14, rior face of the liver by a Colica dextra; 15, Lleo-colica; 16, 16, Vasa intes- fold, and to the right — tinis tenuis. ~ ‘the sublumbar region by con- nective tissue. It describes tie are of acirele, in the concavity of which is lodged the right extremity of the pancreas, and not the ecum as in Solipeds. 4 ‘ M : E 418 THE DIGESTIVE APPARATUS IN MAMMALIA, ox pores Pel nce in the ileo-cecal addon "Its structure is like that i eseri In the large intestine is recognised the cecum, colon, and rectum. The cecum is a small reservoir placed in the right iliac fossa, a little oblique downwards and to the left. It commences at the ileo-czecal valve, has an average of about 24 inches, and terminates by a rounded extremity with a small hollow ation, averaging 3 inches in length, the cwcal or vermiform appendix. The mucous — membrane is like that of animals, and the muscular tunic is the same. The human colon is regularly sacculated, like the small colon of the Horse; it begins in the right iline fossa, above the valvula Bauhini; it ascends to the lower face of the liver, passes abruptly across from right to left, and, arriving at the mr Pe again changes its direction downwards to the iliac fossa : it then again describes the iliac 8, to reach — the mesial line, where it is continued by the rectum. From this ae the colon has — been divided into three portions: the ascending colon, transverse colon, and colon. In the ascending and transverse colon are obseryed three series of separated by three muscular longitudinal bands; the descending colon has only two. There is scarcely anything special to note in the rectum and anus, exce A gee ast ‘ and especially the latter, are very rich in arteries and varicose veins, and bh is se rated rom the rectum by small cavities open in front, and which are found | the ; these are the sinuses of Morgagni. ly . GENERAL AND COMPARATIVE SURVEY OF THE ABDOMINAL OR ESSENTIAL PORTION OF THE = DIGESTIVE TUBE, We have terminated the description of the anatomical characters which distinguish the essential portiou of the alimentary canal in all the domesticated animals, and what — gradations has this study revealed! Let us recapitulate and compare them, before __ showing the admirable harmony which pervades these diverse arrangements, and = adapts them to the variations in general 4 oy poeta: habits, and instincts. 2 Iu the Carnivora which subsist on flesh (Dog and Cat), we have seen a very ample “4 stomach, secreting a gastric fluid throughout thes whole extent of its mucous membrane, and intestines, (relatively) extremely short. In the Omnivora, or mammalia which live on a mixed diet (Pig), we have found a small portion of the internal surface of the stomach occupied by a mucous membrane unfitted to secrete gastric juice, and the intestines relatively of much more considerable ¢ capacity than in Carnivora. I With the Herbivora, which derive their nourishment exclusively from the vegetable ha re kingdom (Ruminants and Solipeds), the surface destined for the production of the gastric juice also singularly diminishes in extent, although the stomach in some of these animals — is remarkable for its extraordinary development. But’ to compensate for this, the capacity of the intestinal canal assumes considerable proportions, and in the various species is in directly inverse relation to the area of the gastric surface. This surface ig relatively more extensive in Ruminants than in Solipeds, all these animals ought — be classed in an inverse order with regard to the evelopment of the intestinal - Slap. Finally, in considering as the internal surface of the stomach (a point of view rational) only those portions of the mucous membrane organised for the secretion gastric juice, we are led to recognise that this surface is in inverse P roportion to that tof the intestine; that it reaches its highest degree of development in ivorous animals; and that it is reduced to the smallest dimensions in Solipeds, animals which, on the a contrary, present a very great development of the intestinal surface. } The nature of the aliment readily accounts for these remarkable differences. — Tees Carnivora, living on substantial food, tuke it in very large semper because they are exposed to frequent fastings; it is, therefore, necessary t they should have a stomach large enough to contain the Nicaaes substances, and to secrete the amount of — gastric juice needed to transform them into assimilable materials. If these animals have a short and narrow intestine, it is because a small surface only is required to absorb the — ng! products of digestion, these being mixed with but a minimum quantity of non-nutriiess #, substances, and readily come in contact with the absorbing membrane. 5 With regard to the Herbivora, their food contains a trifling proportion of nutvities elements inclosed in an extremely abundant matrix, and being compelled to ingest eee ‘if it has to perform its functions more frequently than in Carnivora, it is not required to splay so much activity in a given time. If, on leaving the stomach, the alimentary - ters encounter a vast intestinal surface, it is in order that the reparative materials sersed in the alimentary mass may not escape the absorbent action of that surface, ‘and may be the more effectually brought into contact with it. We have this exemplified suminants ; owing to their double mastication and the triturating action of the many- _ plies, their fool arrives in the stomach proper more comminuted and better attenuated than in the Horse ; the mass, more finely broken up, retains less of the assimilable and oarative matters, and these are more easily seized by the absorbing surface ; and, as a : consequence, the intestinal tube, although longer than in Solipeds, is far from ring the same capacity. _ Analogous considerations explain the reason for the intermediate conformation of the restive canal in Omnivorous animals. _ There is, then, an admirable correlation between the conformation of the digestive tube and the nature of the substances which form the base of the alimentation of animals ; and this harmony is equally apparent when the stomach and intestines are com with _ the other apparatus of the economy, and with the natural habits and instincts of creatures. _ §$o it is that a creature furnished with an ample stomach and narrow intestine, will have ____ sharp teeth and claws to tear its prey, strength and agility to capture it, and will also possess sanguinary instincts; while another, with its ic surfuce greatly diminished, will have intestines as developed in their length asin their capacity, and be distinguished a a bo bow peaceful habits, the absence of aggressive claws, and the crushing and grinding form the principal pieces of its dental apparatus, etc. : ® : ORGANS ANNEXED TO THE ABDOMINAL PORTION OF THE DIGESTIVE Ss CANAL, Bs These organs are three in number: two glands—the liver and pancreas, which pour into the small intestine two particular fiuids, the bile and pan- -ereatic juice ; and a glandiform organ, the spleen, remarkable for its nume- rous connections with different organs of the digestive apparatus, and which for this reason deserves to be studied with it, although it is doubtful, if not improbable, that it has anything to do with digestion. Preparation.—These three organs can readily be studied after removing the intestinal mass, as indicated ut page 385. In order to examine the details of their organisation with more facility, it would be well to detach them altogether with the diaphragm and kidneys, and to lay out the whole on a table. (To stu the relations of these tliree organs with those of the abdominal cavity, it is advisable to place the subject on its . — after removing the intestines, and to detach the posterior part of the body at the 34 on The Liver. (Figs. 182, 211, 216.) ___ *Situation—Direclion—This organ is situated in the abdominal cavity, to the right of the diaphragmatic region, and in an oblique direction down- wards and to the left. _ * Weight.—The weight of the healthy liver, in a middle-sized Horse, is . an Hate and External Surface.—Released from all its connections with the neighbouring organs, and viewed externally, it is seen to be flattened before and behind, irregularly elongated in an elliptical form, thick in its centre, _ and thin towards its borders, which are notched in such a manner as to divide the organ into three principal lobes. This configuration permits it to be studied in two faces and a circumference. The anterior face is convex, perfectly smooth, and channeled by a wide 282 420 THE DIGESTIVE APPARATUS IN MAMMALIA. " yin Ga and deep notch formed for the passege of the posterior vena caya. This fissure extends directly from behind to before, and consequently slightly crosses the general direction of the liver; near the point where the — vena cava leaves the gland to traverse the diaphragm are seen the openings of the principal suprahepatie veins. The posterior face is eq smooth and convex, and_has also a fissure by which the vena porte the hepatic artery and nerves enter, and by which the biliary ducts ; from the liver. This groove is slightly concave towards the left, and follows. the direction of the liver in proceeding obliquely downwards, backwards, and to the left. : The cireumference may be divided into a superior or left, and an inferior hs or right border, united at both extremities by the ellipsis formed by the’ _ liver. The superior border presents, in proceeding from right to left: 1,The insertion of the ligament of the right lobe; 2, The origin of the fissure for the vena cava; 3, A notch for the cesophagus ; 4, The insertion of the left ligament. The inferior border is sharp, and offers two deep notches, which divide the liver into three lobes: a superior or right, an inferior or left, and an intermediate one. The right lobe is usually of medium volume, and has above, on its posterior face, an appendix in the shape of a small — secondary lobule of a triangular form, whose base responds to the com- mencement of the portal fissures: this is the lobus Spigelii. The left lobe is nearly always the largest. The middle lobe, the smallest of the three, is itself divided by secondary notches into several digitations or lobules. Relations.—Viewing the organ in position, in order to study its general relations, it is found that the anterior face is applied against the diaphragm— __ a disposition which augments its convexity in diminishing that of its pos- terior face; and that the latter is in contiguity with the stomach, the _ duodenum, and the diaphragmatic curvature of the colon. The connections proper to each lobe are observed to be as follows: 1, The middle lobe responds to the centre of the aponeurotie portion of the diaphragm; 2, The left lobe touches the left and inferior part of this aponeurosis, and is prolonged to the corresponding point of the fleshy peripheral band of that muscle; 3, The right lobe is in contact with the right and superior part of the muscle ; its upper border touches the right kidney; the pancreas rests against its ‘pase, on the posterior face. a Mode of attachment.—The liver is suspended to the sublumbar wall of the abdomen by the large blood-vessels which enter its fissures, and it a also fixed to the posterior face of the diaphragm by four particular bands. — One of these is carried from. the anterior face of the liver to the phrenic centre, and appears intended to oppose total displacement of the organ; the — other three belong to each particular lobe. A. The ligament of the anterior face of the liver (or coronary ligament) ‘comprises two series of very short aponeurotic fibres, which, arising from the two borders of the vena cava fissure, go to be fixed to the posterior face of the phrenic centre. The peritoneum is folded over it on each sidein passing from the diaphragm to the liver. The adherence of these fibres to the walls of the vena cava is extremely close; and the vena cava itself, being thus in a manner united to the tissue of the liver, it happens that the union of the anterior face of the viscus with the phrenic centre con ‘9 not be more solidly established. o B. The ligament of the left lobe is a wide peritoneal fold, between the two layers of which are some fasciculi of white fibrous tissue. It is detached od » ey y : —s < 1) LS wrk Ay Sa Po ae ow ) ) ORGANS ANNEXED TO THE ABDOMINAL DIGESTIVE CANAL, 421 from the aponeurotic centre, to the left of the cesophageal orifice, and is inserted into the left part of the superior’ border of the liver. C. The ligament of the right lobe is a fold analogous to the preceding, but much shorter, and whose origin, placed very high and near the sub- lumbar parietes, is partly covered by the right kidney. It is inserted into the 3, Right extremity, or ventriculus of stomach ; Fig: 211. 2, Middle lobe ; 4, Right extremity ; Left abdominal wall. THE ABDOMINAL CAVITY, WITH THE LIVER AND OTHER ORGANS, 1, Right lobe of the liver; superior border of the viscus, and sends a small layer to the lobus Spigelii ; most frequently, however, this lobule is sustained by a special peritoneal frenum, given off from the anterior border of the kidney. D. The ligament of the middle lobe (the longitudinal, broad, faleiform, or suspensory ligament) is a falciform and vertical serous layer, whose adherent 422 THE DIGESTIVE APPARATUS IN MAMMALIA, ah border is attached, almost in the median plane, to the posterior face of the i diaphragm, and even to the inferior abdominal parietes, At its free border aia is a fibrous cord (the round ligament), formed by the obliteration of the foetal umbilical vein. By its upper part, it penetrates a secondary nofch in the middle lobe, and is prolonged on the anterior face of this to the point where the vena cava traverses the diaphragm. Srrvoture.—As elements in its structure, the liver offers for study: 1, A serous membrane ; 2, A fibrous capsule ; 3, The proper and fu tissue of the organ. 1, Szrovs Mempranr.—This membrane is only an expansion of the peri- toneal bands or ligaments already described, and of which the two, on arriving at the organ, separate to become developed on its surfaces, and to completely cover it, except in the anterior and posterior fissures. 2. Frsrovus, or Guisson’s Carsute.—This, the proper envelope of the liver, is formed by a very fine fibrous membrane, closely adherent to — z the preceding layer on the one side, and to the tissue of the liver on the other. It penetrates the substance of that tissue in passing around the vessels lodged in the posterior fissure, and from its inner face it sends a_ multitude of lamellar partitions, which separate the hepatic granulations, and form a veritable framework in the interior of the organ. The ~ presence of this capsule has been denied, but its existence is not to be. doubted in all the domesticated animals; it is particularly well developed in Ruminants. 3. Proper Tissuz or tHe Liver.—The proper substance of the liver is distinguished by its bluish-brown or violet hue, the shades of which vary much according to the subjects. It is heavy, compact, and so friable that it is crushed by the most moderate pressure. It is composed of polyhedrie granulations from 1—-20th to 1-10th of an inch in diameter, which are readily enough distinguished from one another through the peritoneum on the surface of the organ, particularly when the septa thrown in between them from Glisson’s capsule are hypertrophied from some slight chronic irritation. . | Sometimes the hepatic lobule is uniform in colour throughout; often it shows a red central point, with a yellow circle around it, and an interrupted red ring circumscribing this again, and which communicates with a similar circle belonging to the adjoining lobules, so as to compose a network at the surface of the gland; at other times the lobules are yellow at the centre and red at the circumference, All these appearances, the study of which at one time was considered of much importance, are uncertain, and may vary in a thousand ways, in combining withjone another ; so that they really demand but little attention, due as they are to the greater or less degree of plenitude of the different vessels entering the lobule. As the liver is composed of lobules placed beside each other, we will describe one; as when its structure is well known, we will be familiar with the organisation of the entire organ. In a hepatic lobule we find: 1, Hepatic (or biliary) cells ; 2, Biliary canal- iculi (or ducts); 3, Afferent vessels; 4, An efferent vessel ; 5, Lymphaties ; 6, Connective tissue. Hepatic cells—These are polygonal or round, and much resemble squamous epithelium; their diameter varies from 1—-500th to 1-200th of an inch. They are composed of a thin enveloping membrane and yellow- coloured contents. The latter comprise one or two nuclei with nucleoli, coloured granules, biliary matter, a small mass of a substance which has been ‘ rere (ory Ry eer = —ws . r+ ’ ORGANS ANNEXED TO THE ABDOMINAL DIGESTIVE CANAL. 423 studied by Bernard and Schiff, and named “animal amidlon;” and, lastly, adipose granules, whose volume and quantity vary with the condition of the i or the period of digestion at which the liver has been removed. The hepatic cells are situated in the network formed by the vessels of the lobule, and constitute its principal portion. am Ducts.— Destined to carry away the bile secreted in the interior of the hepatic lobule, the bili- ary ducts form around it a kind of girdle that accompanies the interlobular branches of the yena porte. Within and with- out, this girdle sends off small longments: the first bring it into communication with the ducts of the neighbouring lobules; the second enter the substance of the lobule and are soon lost. The wall of the biliary ducts is a thin amorphous membrane, lined by polygonal pe smaller than the hepatic A Fig. 212. B . A. Portion of a hepatic column, showing i - The origin of the biliary or nent secreting a a B, Secreting cells detachat ; tic ducts in the interior of a, In their normal state; 6, A cell more highly the lobules is still a vexed magnified, showing the nucleus and distinct oil- question in histology. It was en c, In various stages of fatty degenera- believed, and some authorities still believe, that the ducts terminate in pouches, at a short distance from the periphery of the lobule. But it has been remarked that an injection introduced by the ductus choledochus does not remain near the periphery of the lobule, but, on the contrary, penetrates to its centre by passing between the hepatic cells; and from this it is admitted that the hepatic ducts fur- nish a very fine network around each of the cellular elements of the liver (Fig. 213). Nevertheless, there are histologists who do not share in this opinion, who assert that these terminal ducts have no — walls, and that the supposed networks they orm is only a simple system of intercellular spaces distended by the injection. Afferent vessels.—-These are the branches of the : portal vein and hepatic artery. The portal vein, nmiary capmarres or after reaching the interior of the liver, divides into TH® Raserr’s LIVER. peely decreasing vessels, until it terminates by PAE OF A oe orming the interlobular. or subhepatic veins, These xr op tun uitany vessels surround the lobule, communicate with the DUCTS IN RELATION TO neighbouring interlobular veins, and give off a large THe HEPATIC CELLS. number of twigs to the interior of the lobule, where 4, Capillaries of the biliary they anastomose, and constitute the hepatic capillary at b, rip ran plexus. The hepatic artery furnishes ramuscules, —%\ilimy ‘ucts; 4 Ca- which mix with the ramifications of the portal vein Paget Ay in the (vaginal) plexus. The principal branches of the latter are all Fig, 213, 424 THE DIGESTIVE APPARATUS IN MAMMALIA, directed from the periphery towards the centre of the lobule, where they unite to form the afferent vessel. It results from this arrangement that the hepatic cells which fill the spaces between the vessels are placed in radiating series. Efferent series —Situated in the centre of the lobules, this vessel receives all the ramifications of the capillary plexus, and is named the intralobular or central supra- hepatic vein. It is voluminous, and communicates with the other intralobular veins. (These intra- lobular veins terminate in the larger trunks that run along the bases of the lobules, and are named the sublobular veins.) Lymphatics.—In a hepatic low bule are found very fine lymphatie vessels that surround the branches b of the hepatic plexus, where they HORIZONTAL SECTION OF THREE suPERFIcraL form the lymphatic vagine, or LOBULES, SHOWING ‘THE TWO PRINCIPAL canals which contain the blood- SYSTEMS OF BLOOD-VESSELS. vessels. a, Re tigreraang Menai ersonc ati _ the Connective tissue-—The intra- e 1c =6velns; W, Us nteriobular nexus, - a > faced by branches of the portal vein. lobular connective tasetie 16 ecanity; : the lobule being almost entirely composed of cells or capillaries: so that only some trabecule exist around the lymphatic sheaths. There is, however, a larger quantity in the inter- lobular spaces; and in some animals—especially the Pig —Glisson’s capsule sends somewhat thick lamelle of connective tissue between these lobules. Exorrrory APPARATUS.— This is very simple in Soli- peds, and is composed of a vessel named the ductus chole- dochus, resulting from the union of several trunks lod in the posterior fissure of the liver, and which come from the three lobes. Traced in the substance of the hepatic tissue, these branches divide into SECTION OF A SMALL PORTION OF THE LIVER OF A yore and more attenuated RABBIT, WITH THE HEPATIC OR INTRALOBULAR ramuscules that arise from ve the periphery of the lobules, and are continuous with the biliary ducts that envelop and penetrate these. Course.—At its exit from the liver, the ductus choledochus is placed between the layers of the gastro-hepatic omentum, and ascends to the wall of the duodenum, which it passes through at about six inches from the pylorus, Fig. 214. i St Nes uy 4 Fig, 215. iia ORGANS ANNEXED TO THE ABDOMINAL DIGESTIVE CANAL. 425 along with the principal pancreatic duct. The orifices of these two canals are surrounded by a circular mucous fold (ampulla of Vater), which is usually very prominent, and acts as a valve in preventing the entrance of alimentary substances into the apertures it encircles; this office it fills so well, that it will not even allow the air with which the duodenum is inflated to pass into the ducts. Fig. 216. EXCRETORY APPARATUS OF THE HORSE’S LIVER. 1, Left lobe of the liver; 2, Middle lobe; 3, Right lobe; 4, Lobule of Spigel; 6, Posterior vena cava at its entrance into the liver; 7, Vena porte; 8, Ductus choledochus ; 9, Pancreatic duct ; 10, Common entrance of these two ducts into the small intestine. There enter into the structure of the ductus choledochus: 1, A fibrous which some anatomists believe contains unstriped muscular fibres ; 2, Cylindrical epithelium ; 3, Numerous racemose glands, opening on its inner surface by very small orifices. Vessets AnD Nerves or THE Liver.—The blood-vessels are the hepatic artery, portal vein, and suprahepatic veins. The hepatic artery is a branch of the cceliac, and enters the gland by the a ure, in company with the portal vein and ductus choledochus. n the liver it divides into very fine ramifications which join the intra- lobular plexus, anastomose on the surface of the biliary ducts, or expand either on the serous membrane, or in the walls of the portal vein. The portal vein is the functional vessel of the liver. It reaches that organ by the posterior fissure, and Glisson’s capsule accompanies its rami- fications as far as the hepatic lobules, where they form the plexus of sub- hepatic veins. The suprahepatic (or sublobular) veins are so named because they gain the antero-superior face of the viscus to open into the posterior vena cava. They carry away the blood that has been brought by the portal vein and hepatic artery. Their origin is due to the union of the intralobular veins, which make a passage through the hepatic tissue with which their walls are immediately in contact, gradually join each other, and enter the posterior vena cava on its way through the anterior fissure of the liver. The number of trunks (hepatic) entering this vessel is considerable, but the majority are verysmall ; the principal confluent is placed at the anterior extremity of the fissure. The lymphatics form a fine supérficial plexus, easy to inject; with deeper 26 THE DIGESTIVE APPARATUS IN MAMMALIA, networks placed around the vessels that penetrate by the posterior fissure. In the lobules they are disposed as described above. Joined to the lymphatics of the stomach, they constitute a single trunk that goes to the sublumbar receptacle. The nerves are more particularly derived from the solar plexus, althou the pneumogastric and diaphragmatic also supply filaments to the liver. They interlace around the hepatic artery and porial vein; their mode of termination is unknown. rat Functions.—The most important considerations are attached to the study of the functions of the liver; but we cannot enter into them in detail with- out going beyond our subject. Besides, there is yet much to be learned respecting them. The liver is a biliary and glycogenetic gland. It secretes the bile at the expense of the blood of the portal vein, which comes from the intestinal tunics charged with the assimilable substances absorbed by the veins from the villi. This fluid is submitted to modifications in the interior of the liver, by which it is relieved of certain matters, while at the same time it furnishes the biliary secretion. The bile is, therefore, in this respect an excrementitious secretion ; though all its elements are not thrown off, some of them acting on the alimentary | substances, and others being absorbed. From the most recent researches, it would appear that it has a share in the purification of the blood, in digestion, and in calorification; in the latter especially, as its absorbed elements are very rich in carbon and hydrogen, bodies eminently adap for the production of animal heat. The liver is also a glycogenetic gland, this function having been demon- strated to pertain to it by Bernard. The sugar formed in the liver finds its way into the blood, and leaves the organ by the suprahepatic veins. It is elaborated in the hepatic cells by the transformation of the substance known as “animal amidon,” which is brought into contact with a kind of diastase that exists with it in their interior. Lastly, it is also believed that the liver is a hematogenetic organ, the red globules being formed in its mass at the expense of the fibrine of the blood that passes through it. It will thus be seen that the liver furnishes two very different products— bile and sugar. The knowledge of this fact, combined with the internal arrangement of the organ, has led some anatomists to consider the organ as two glands reciprocally contained within each other. But this hypothesis loses its value if it be admitted that the hepatic ducts pass between the cells to the centre of the lobule, and that in this portion they are destitute of epithelium. It is therefore probable that the sugar and bile are produced in the large hepatic cells, and that the first passes into the veins, while the second is poured into the biliary ducts. In Solipeds, the secretion of bile, though most active during the digestive period, yet goes on in a continuous manner. (Certain deductions of a pathological kind are based upon the foregoing anatomical facts, and have an important bearing with regard to comparative — pathology. They have been pointed out by Wilson, and are as follows :— Each lobule is a perfect gland; its structure and colour are uniform, and it has the same degree of vascularity throughout. It is the seat of a double venous circulation ; the vessels of the one (hepatic) being situated ip the centre of the lobule, and those of the other (portal) in the circumference, Now the colour of the lobule, as of the entire liver, depends chiefly on the — = paca = mao ors = al oe ORGANS ANNEXED TO THE ABDOMINAL DIGESTIVE CANAL, 427 _aceeyom of blood contained within these two sets of vessels; and so long as circulation is natural, the colour will be uniform. But the instant that any cause is developed which shall interfere with the free circula- seed fd either, there will be an immediate diversity in the colour of the Thus, if there be any impediment to the free circulation of the venous blood through the heart or lungs, the circulation in the hepatic veins will be retarded, and the sublobular (or supralobular) and intralobular veins will become congested, giving rise to a more or less extensive redness in the centre of each of the lobules; while the marginal or non-congested portion a distinct border of a yellowish white, yellow, or green colour, according to the quantity or quality of the bile it may contain. “ This is : ive congestion’ of the liver, the usual and natural state of the organ death ;” and, as it commences with the hepatic vein, it may be called the first stage of hepatic venous congestion. But if the causes which produced this state of congestion continue, or be from the beginning of a more active kind, the congestion will extend through the lobular venous plexuses “ into those branches of the portal vein situated in the interlobular fissures, but not to those in the spaces, which being larger, and * giving origin to those in the fissures, are the last to be’ congested.” In this second stage the liver has a mottled appearance, the non-congested substance is arranged in isolated, circular, and ramose patches, in the centres of which the spaces and parts of the fissure are seen, This is an extended degree of hepatic venous congestion ; it is “ active congestion” of the liver, and very commonly attends disease of the heart and lungs. _ These are instances of partial congestion ; but there is sometimes general congestion of the organ. “In general congestion the whole liver is of a red colour, but the central portions of the lobules are usually of a deeper hue than the marginal portions.”) _ Degvye.orment.—The liver of the foetus is remarkable for its enormous development. Its function commences early, for at birth the intestines are filled with meconium, a product of the biliary secretion. A more detailed description will be given when the general development of the foetus comes to be studied. 2. The Pancreas. This organ has the greatest resemblance to the salivary glands in its structure and physical properties ; and for this reason it has been named the abdominal salivary gland. Situation.—It is situated in the sublumbar region, across the aorta and posterior vena cava, in front of the kidneys, and behind the liver and stomach. Its weight is seventeen ounces. Form and Relations—The pancreas is rather irregular and variable in form, according to the kind of animal. Flattened from above to below, traversed obliquely from its inferior to its superior face by an opening for the passage of the portal vein, and which is named the pancreatic ring, this gland is sometimes triangular, sometimes oblong, and curved on itself; it is under the latter form that we will notice it. Its faces present the lobulated aspect of salivary glands. The superior adheres by cellular tissue to the aorta, posterior vena cava, cceliac trunk, solar plexus, splenic vessels, and the right kidney and supra-renal capsule ; © it is covered by the peritoneum for a certain portion of its extent. The inferior responds to the base of the cwcum and the fourth portion of the 428 THE DIGESTIVE APPARATUS IN MAMMALIA, colon, through the medium of « thick layer of cellular tissue. The anterior border, concave and undulating, is in contact with the duodenum and the left. oe to a extremity of the stomach. The posterior is very convex, especially to the right, and near its middle presents a notch for the reception of the portal — vein before its entrance into the ring. he right extremity (or head), the thinnest, adheres to the duodenum, and shows the excretory ducts of the == gland. The left is carried towards the base of the spleen, in passing between the left extremity of the stomach and the kidney of the same side. Structure.—It resembles the salivary glands, except in its epithelium. This, instead of being simple polygonal cells lining the thin, structureless membrane of the ultimate follicles, is very granular, and fills these cavities. The gland receives its blood by the hepatic and great mesenteric arteries ; the nerves come from the solar plexus. Excretory apparatus.—The pancreas has two excretory ducts : a principal, described by Wirsung, whose name it bears, and an accessory. The duct of Wirsung, lodged in the substance of the gland, but nearer the superior than the inferior face, at first comprises two or three thick branches, which soon — unite to form a single trunk that emerges from the pancreas by the left extremity of the organ. Larger than the ductus choledochus, it opens, as already stated, at the same part of the duodenal surface. The accessory duct (ductus pancreaticus minor) is much smaller; it leaves the principal trunk, receives some branches in its passage, and opens alone into the small intestine, directly opposite the duct of Wirsung. The ductus choledochus and the duct of Wirsung do not pass directly through the wall of the intestine, but obliquely, like the entrance of the ureters into the bladder. They open in the middle of a circular valve—the ampulla of Vater. This ampulla is limited by a thick primary mucous fold, and within this is a second, thinner, beneath which the ductus chole- dochus opens ; at the bottom of the space circumscribed by this second fold, beneath a free mucous lip, is seen the duct of Wirsung. Funcrions.—From the researches of Bernard, it appears established that the fluid secreted by the pancreas emulsifies fatty matters and renders them absorbable. . “ah es 8. The Spleen. The spleen differs from glands not only in the absence of an excretory duct, but also in the other details of its organisation. It has been consi- dered as a vascular gland, whose uses are not yet determined in a precise manner, Situation.—It is situated in the diaphragmatic region, close to the left hypochondriac, and appears as if suspended in the sublumbar region, as well as at the great curvature of the stomach, — Form —Direction—Relations—The spleen is falciform, and directed obliquely downwards and backwards. It has two faces, two borders, and a point, ' ; The external face is in relation with the muscular portion of the diaphragm, and is moulded to it. The internal, slightly coneaye, touches the large colon; it has sometimes a small lobule, or offers traces of lobula- tion. The posterior border is convex, thin and sharp. The anterior, thicker, concave, and bevelled at the expense of the internal face, is channeled by a slight longitudinal fissure which lodges the splenic vessels and nerves ; it wh — ORGANS ANNEXED TO THE ABDOMINAL DIGESTIVE CANAL, 429 receives the insertion of the great mesentery, by which it is held to the greater curvature of the stomach. The base, or superior extremity, is thick and wide, and responds to the left kidney and the corresponding extremity _ of the pancreas; it shows the insertion of the suspensory ligament. The int, or inferior extremity, is smooth and thin. _ Weight—The average weight is 32 ounces; but it is sometimes of enormous dimensions—as much as three or four times its normal volume. Mode of attachment.—The spleen is a floating organ, whose displacements are limited by a suspensory ligament, and the great (or gastro-splenic) omentum. The first is a peritoneal fold which proceeds from the anterior border of the left kidney and the sublumbar wall, and is strengthened by the elastic fibrous tissue comprised between its two layers. It is fixed to the base of the spleen, and is confounded, inwardly, with the great omentum. The latter is already known as proceeding to the colon, and in its passage becoming attached to the splenic fissure, whence it extends over the sur- face of the organ to form its serous covering. Srructure.—The tissue of the spleen has a violet-blue colour, sometimes approaching to a red hue; it is elastic, tenacious, and soft, yields to the pressure of the finger, and retains the imprint. Enveloped externally by the peritoneum, its substance includes a fibrous framework, splenic pulp, Mal- pighian corpuscles, vessels, and nerves. Serous membrane.—This is developed over the whole surface of the organ, except in the fissure of the anterior border. Its internal face adheres most intimately to the proper tunic of the spleen. It is only an expansion of the serous bands which limit the movements of the viscus. Fibrous framework.—Under the peritoneal membrane is a thick, resisting, fibrous tunic, roughened and granular on its exterior, and sending from its oe into the interior of the mass a multitude of prolongations called , which cross in all directions, forming a cellular network whose numerous narrow meshes contain the other elements of the organ. In washing a morsel of spleen in a jet of water, the latter are removed, and the outlines of this fibrous structure are fully exposed. Ifa stream of water is = through the splenic artery, the same result will be arrived at. élliker has found in the proper tunic of the spleen, and in its trabecule, a particular contractile tissue, the muscular cell-fibres, mixed with fasciculi of elastic or inelastic fibrous tissue. (The proper coat, the sheaths of the vessels, and the trabecule consist of a dense mesh of white and yellow elastic fibrous tissues, the latter considerably predominating. It is owing to the presence of this tissue that the spleen possesses a considerable amount of elasticity, admirably adapted for the very great variations in size that it ts under certain circumstances. In some of the mammalia, in addition to the usual constituents of this tunic, are found numerous pale, flattened, spindle-shaped nucleated fibres, like unstriped muscular fibre. - It is probably owing to this structure, that the spleen possesses, when acted upon by the galvanic current, faint traces of contractility.) Splenic pulp.—This name is given to a reddish pultaceous material, which partly occupies the aveolar framework formed by the intersections of the trabecule. It is sustained by a very delicate reticulum of connective tissue, and is composed of numerous elements, such as pigment granules, free nuclei, large cells with several nuclei, lymphoid elements, and blood- es in a state of decomposition or transfurmation. These globules are free or enveloped in an albuminoid membrane. (The proper substance of the spleen consists of coloured and colourless elements. The coloured 430 THE DIGESTIVE APPARATUS IN MAMMALIA, are composed of red blood-globules and coloured corpuscles, either free or included in cells, Sometimes unchanged blood-dises are seen included in Fig. 217. a a 4 —_ > >" included blood-dises are altered both in form and colour. Besides’ these, numerous deep-red, or red- dish-yellow, or black corpuscles and crystals, either single or gated in masses, are seen di throughout the pulp substance ; these, in chemical composition, are closely allied to the hwmatine of the blood. The colourless ele- ments consist of granular matter ; nuclei, about the size of the red blood-dises, homogeneous or gra- nular in structure; and nucleated ? elements form a large proportion of the entire bulk of the spleen in well- nourished animals; whilst they diminish in number, and occasion- ally are not found at all, in starved animals. The application of chemi- BRANCH OF SPLENIC ARTERY WITH ITS RAMI- eal tests shows that they are essen- FICATIONS STUDDED WITH MALPIGHIAN COR- PUSCLES. tially a proteine compound.) = Malpighian corpuscles.—These are contained, like the pulp, in the meshes of the fibrous framework, and are enveloped by this pulp. Scattered along the track of the small arteries, these corpuscles are visible to the naked eye, and appear as whitish closed- Fig. 218. A SINGLE SPLENIC CORPUS- CLE, FROM THE SPLEEN OF THE OX. 1, External tunic, or mem- brana propria; 2, Gran- ular contents; 3, Part of a small artery; 4, Its sheath, derived from the external tunic of the spleen, with which the corpuscle is closely con- nected. sacs, cells, and nuclei floating in a plasma, The Malpighian corpuscles are constituted by the adven- titious tunic of the arteries, in which lymphoid ele- ments are accumulated at certain points. They are therefore allied to the closed follicles of the intestines. (These splenic or Malpighian corpuscles, are round, whitish, semi-opaque bodies, glutinous in consistence, and disseminated throughout the sub- stance of the organ. They are more distinct in early than in adult life or old age, and vary con- siderably in size and number. From the manner in which they are appended to the sheaths of the- smaller arteries and their branches, they resemble the buds of the moss-rose. Each consists of a mem- — branous capsule, composed of fine pale fibres inter- lacing in all directions. ‘The blood-vessels ramify- ing on the surface of the corpuscles, are the ae ramifications of the arteries to which the sacculus is connected, and also of a delicate capillary plexus, similar to that surrounding the vesicles of other glands. These vesicles have also a close relation with the veins, and the vessels begin on the surface of each vesicle through- out the whole of its circumference, forming a dense venous mesh in which a cell; but more frequently the 2 vesicles in small numbers. These - ORGANS ANNEXED TO THE ABDOMINAL DIGESTIVE CANAL. 481 each of these bodies is inclosed. It is probable that, from the blood con- - tained in the capillary network, the material is separated which is occa- sionally stored up in their cavity; the veins being so placed as to carry off, under certain conditions, those contents that are again to be dis- charged into the circulation. Each capsule contains a soft, white, semi-fluid substance, consisting of granular matter, nuclei similar to those found in the p, and a few nucleated cells, the composition of which is apparently salary These bodies are very large, after the early periods of diges- a tion, in well-fed animals, and especially those fed upon albuminous diet. In starved animals, they disappear altogether.) Arteries.—These emanate from the splenic artery at different elevations, and plunge into the tissue of the spleen, preserving their reciprocal independence. Their terminal ramifications do not open, as has been said, into venous sinuses, but into minute tufts of capillaries, which traverse the splenic pulp, to be continued by the venous network. Veins. —All the venous branches of the spleen open into the splenic vein, and are lodged with the corresponding artery in the fissure of the organ. Traced from their commmencement, they are seen to gradually lose their constituent membranes, and to open into sinuses which are only lined by the epithelium of the vessels. It is in these sinuses that the network of yenous capillaries which succeed the arterial capillaries, originates. Lymphatic vessels—These are found on the external surface of the organ, and along the track of the blood-vessels. (They invest these with a distinct sheath, between which and the parictes of the vessels numerous lymph corpuscles may be found.) erves.—They are derived from the solar plexus, and enveloping the splenic artery, with it enter the spleen. (They appear to be very large, but this appearance is due to the great proportion of ordinary fibrous tissue investing them.) From what has been said above respecting the arrangement of the mic arteries and veins, it will be perceived that the areole formed by trabecule of the fibrous framework contain the pulp, and are not in direct communication with the arterial capillaries. Such an organisation belongs to erectile tissues. The arteries communicate with the veins proper by venous canals channeled in the splenic pulp, and are lined only by ellip- tical cells. These venous canals are extremely dilatable, especially in the Horse. When the splenic vein is inflated, their walls separate and back the pulp, they become considerably enlarged, and distend the cells of the fibrous structure, but the air does not reach the interior of these cells. Funcrions.—Nothing precise is known regarding the functions of the spleen ; though they must be of very secondary importance, because animals in which the organ has been extirpated, and which have recovered from the consequences of the operation, have continued to live in apparent good health. Numerous hypotheses have been formed on this subject; two of which, founded on the study of the anatomical peculiarities of the spleen tissue, and on exact physiological observations, are as follows: 1, The spleen is a diverticulum for the portal vein; 2, The red globules are destroyed in the With regard to the first hypothesis, it is evident that, owing to the resence of the venous sinuses already mentioned, and their great dilata- ility, as well as to the elasticity and contractility of the spleen tissue, the organ is favourably constructed to act as a blood reservoir. M. Goubaux, 432 THE DIGESTIVE APPARATUS IN MAMMALIA, — = i= on the other hand, has demonstrated that there is always an augmentation in the spleen’s volume when an animal has ingested bee. quantities of water, the consecutive absorption of which determines a certain tension in the portal venous system. The second opinion, emitted by Kélliker, is founded on the existence in the splenic pulp of blood-globules in a state of decomposition, and in the analyses made by J. Beclard of the blood in the splenic vein, which have proved that there is a notable diminution in the proportion of lobules. ? Sa . It is to be remarked that, in the researches undertaken to discover the functions of the spleen, account has not been taken of the connections —__ existing between this organ and the great omentum in the majority of mammals, and which testify that the spleen is only, properly pase Bi a vascular appendagé placed on the track of this omentum. But the uses of this vast peritoneal fold are themselves little understood. Might they not be included with those which are presumed to belong to its appended organ ? . saa 4 : Ay >» * ‘Ae —. ad DIFFERENTIAL CHARACTERS IN THE ANNEXED ORGANS IN THE ABDOMINAL PORTION OF — : THE DIGESTIVE CANAL IN OTHER THAN SOLIPED ANIMALS, The important differences these organs offer in the domesticated mammals belong — more particularly to the liver. 1. Liver.—In the domesticated mammals other than Solipe:ls, the liver exhibits vari- —__ ations in form, volume, and position, which have no iafluence on its organisation: so that = the study of these possesses but a mediocre attraction, This is not so, however, with re- gard to the.exeretory apparatus, the arrangement of which is complicated, and becomes __ very interesting. The biliary duct, in fact, on leaving the fissure of the portal vein,and = before reaching the intestine, gives rise to a particular conduit which is detached at an acute ungle, and which, after a course of variable length, according to the size of the __ animal, becomes dilated into a vast sac, the so-called gall-bludder. ~ : In all treatises on anatomy, the special conduit is designated the eystie duct, that : portion which precedes its origin being named the hepatic duet ; while the appellation of ductus communis choledochus is reserved for the section which goes to the intestine. But these distinctions are vicious, and we limit ourselves to the recognition of: (a) A ductus choledochus exactly like that of Solipeds, and like it extending from the posterior fissure, where it orizinates by the union of several branches, to the duodenum; and(b)a cystic duct, which branches suddenly into the choledic duct, and terminates in the gall- bladder a. The gall-bladder is a reservoir with membranous walls, in which the bile aceumn- lates during the intervals of digestion. This sac, lodged wholly, or in part, in a fossa on — the posterior face of the liver, is oval or pyriform, and presents a fundus and neck, Its parietes comprise three tunics: an external, of peritoneum : a middle, formed of dartoid -, tissue ; and an internal or mucous, continuous with that of the various biliary ducts. : b. The cystic duct extends in a straight line from the neck of the gall-bladder tothe choledic duct. It adheres intimately to the tissue of the liver, and does not exhibit,in- = ternally, the spiral valves which have been described in Man. In opening it longitudi- __ nally, there are discovered, at least in Ruminants and the Carnivora, veld. small orifices which pierce the wall adherent to the tissue of the liver: these are the openings of a8 several minute but particular biliary canals, named the hepatico-cystic ducts, a e. The ductus communis choledochus comports itself exactly as in Solipeds. It is ss much wider than the cystic duct, and opens sometimes alone, sometimes with the pam- creatie canal, into the duodenum in a manner which, up to a certain point, remindsone = of the mode of termination of the ureters. Instead of —s perpendicularly across the = intestinal parietes, it first pierces the muscular layer, follows for a short distance between = it and the mucous membrane, and then opens on the internal face of the latter byan orifice which is encircled by a valvular fold, as in the Horse. Such is the excretory apparatus belonging to the liver in animals provided with a gall-bladder. In these animals the biliary secretion is certainly continuous, as in the Horse; but in the intervals of digestion the bile, instead of flowing directly on to the intestinal surface, passes into the gall-bladder by the cystic duct, and there ORGANS ANNEXED TO THE ABDOMINAL DIGESTIVE CANAL, 433 accumulates. When digestion commences again, this reserve of bile is thrown into the ductus choledochus by the contraction of the muscular fibres of the cyst, and by the of the abdominal viscera; it meets that which comes directly from the liver, and with it is carried to the duodenum. We will now glance at the particular arrangement of this viscus in each species. In the Oz, the liver is entirely confined to the right diaphragmatic region. It is thick, voluminous, and scarcely notched at its periphery ; so that it is difficult, if not impossible, to distinguish three lobes in it, the lobus Spigelii alone being detached from the mass of the organ. The gall-bladder, fixed towards the superior extremity, is nearl always floating; near its neck it receives the insertion of several large conduits, which come directly from the upper part of the liver, The ductus choledochus opens alone at Fig. 219. LIVER OF THE DOG, WITH ITS EXCRETORY APPARATUS. D, Duodenum and the intestinal mass; P, Pancreas; r, Spleen; e, Stomach; f, Rectum ; rk, Right kidney; n, Gall-bladder ; ch, Cystic duct; rr, Liver; F’, Lobe of the liver, prepared to show the distribution of the vena porte and hepatic vein; vp, Vena porte; vi, Hepatic vein; d, Diaphragm; ve, Vena cava; c, Heart. a t distance from the pylorus; M. Colin has found it to be 24} inches in one cow, and 294 inches in another. In the Sheep and Goat, the form and position of the liver differs but little from that of the Ox. The ductus choledoclius, however, unites with that of the pancreas, and terminates at 12 to 16 inches from the pylorus. In the Pig, the liver has three well-narked lobes; the middle carries the gall- bladder. ‘The ductus choledochus opens alone at 1 or 14 inches only from the pylorus, Tn the Dog and Cat, the liver is very voluminous, is deeply notched, and is divided into five principal lobes. The middle lobe-has the gall-bladder attached to it, and gives it complete lodgment in a fossa. 2p _ 434 THE DIGESTIVE APPARATUS IN MAMMALIA, In the Dog, the ductus choledochus, joined to a small branch from the pancreatic enters the intestine at a variable distance from the pylorus, depending upon iene a the animal, but usually between 1} and 47 inches. In the portion comprised the intestine and the origin of the cystic duct, it receives several biliary canals of some- what considerable diameter. In the Cat, the ductus choledochus is most frequently = __ inserted from about 1 to 1} inches from the pyloric orifice ; it opens immediately along- side the pancreatic duct when it does not join it. 2. Pancreas.—In the Oz, the pancreas is not placed across the sublumbar but is comprised between the layers of the mesentery, to the right of the great mesenteric artery. The excretory duct is single, and opens into the small intestine at from 14 to 16 inches beyond the ductus choledochus, In the Sheep and Goat, there is the same general arrangement, but the exeretory duct opens with that of the liver. In the Pig, this duct is inserted at from 4 to 6 inches behind the ductus choledochus, The pancreas of the Dog is extremely elongated, and included between the la the mesentery which sustain the duodenum. It is curved at its anterior oxi behind the stomach, to one side of the median line. Its excretory duct, usually single, pierces the intestinal membranes 2 inches beyond the hepatic duct (Fig. 219, m). a in the mode of insertion of the excretory duct, which has been described in noti duetus choledoclius, the pancreas of the Cat comports itself exactly like that of the : 3. Spleen —In Ruminants, the spleen is not supported by the great omentum, but adheres to the left side of the rumen and diaphragm. It is not falciform, and its breadth is the same throughout its extent. In the Carnivora, it is suspended to the great omentum at a certain distance from the left sac of the stomach. It is irregularly faleci- form, its point is less acute than in Solipeds, and is directed upwards. COMPARISON BETWEEN THE ANNEXED ORGANS OF THE ABDOMINAL PORTION OF THE DIGESTIVE CANAL IN MAN AND THOSE OF ANIMALS. 1. Liver.—Like that of Ruminants, the human liver is situated in the right excava- tion of the lower face of the diaphragm. Its direction is nearly horizontal; its shape is oval, and its ave weight from forty-nine to fifty-three ounces, The posterior border is thick and round; the anterior border and extremities thin and sharp. The upper face, which in expiration ascends to the fourth rib, is divided into two portions or lobes— = right and left, by the falciform ligament; it is smooth and con- The inferior face has three trows, or fosse: two longitu- dinal, united by a tran re- sembling altogether the letter H. The transverse furrow represents that on the posterior as of the liver of animals, and its des- longitudinal furrow 1] the obliterated umbilical vein; the left, well marked before and be- hind, lodges the gall-bladder in front, and the inferior vena cava behind. This face has four lobes, the right and left, and two ~ transverse furrow is the lobus UNDER SURFACE OF THE HUMAN LIVER. uadratus, and behind the same 1, Right lobe; 2, Left lobe; 3, Lobus quadratus; 4, ure is the lobus Spigelii. Lobus Spigelii: 5, Lobus caudatus; 6, Longitudinal On the lower face of the right fossa; 7, Pons hepatis; 8, Fossa of ductus venosus; Jobe are three depressions; an 9, Inferior vena cava; 10, Gall-bladder; 11, Trans- anterior or impressio colica; a verse fossa; 12, Vena cava; 13, Depression corres- pee middle one, impressio vesiow ; aa ; ponding to the curve of the colon; 14, Double a small posterior one, which depression produced by right kidney and supra-renal receives the supra-renal capsules, capsule, impressio renalis, 2. Pancreas.—This organ is very elongated transversely, like that of the Dog and Cat. It is closely applied against — the lumbar vertebre, as in the Horse, but its anterior face is much more enveloped by the peritoneum. Its right extremity rests on the duodenum, while the left corresponds ity, 4 tination is the same. The a middle lobes. In front of the — if, % b« uf ee THE DIGESTIVE APPARATUS IN BIRDS. 435 and left kidney. Its texture is consistent, and of a greyish-white colour. The ; of Wir terminates along with the ductus choledochus in the ampulla of Vater. _ 8. Spleen.—This is not falciform, but quadrangulur; its inferior extremity is larger than the a pele It is attached to the stomach by the great omentum, and its inner is d into two portions by a salient ridge ; a little in front of this is a fissure, h e hilum by which vessels enter it. CHAPTER III. ; THE DIGESTIVE APPARATUS OF BIRDS, ‘ = on the same plan as that of Mammals, the digestive apparatus of Birds eve offers in its arrangement several important peculiarities, which will be hurriedly noticed in reviewing, from the mouth to the anus, its different sections. . Mouh—The essentially distinctive character of the mouth of birds consists in the absence of lips and teeth, these organs being replaced by a horny production fixed _ toeach jaw, and forming the salient part termed the beak. In the Gallinacx, the beak is short, ted, thick, and strong, the upper mandible being curved over the lower. In Palmi; it is longer, weaker, flattened above and below, widened at its free extremity, and furnished within the mouth, on the borders of each mandible, with a series of thin and sharp transverse lamin to cut the herbage. — 9 _ The muscular ndage, or tongue, lodged’ in the buccal cavity, is suspended to a rema mobile hyoidean apparatus. Covered by a horny epithelium, and previded at __ its base with severe! papill directed backwards, this organ always affects the form of __ the lower jaw: in Poultry it is like the barbed head of an arrow, the point being directed forwards: in ce pep this saggital form is still more marked ; in Geese and Ducks, on the contrary, in consequence of the wide shape of the beak, it has not this disposition, and is eofter and more ficxible than in the Gallinace. = With to the salivary glands annexed to the mouth, they are imperfectly Gurlt! peeks of a parotid gland situated beneath the zygomatic arch, whose duct opens into the mouth behind the commissure of the jaws. Meckel names this organ the UUM aay Section tho gland of! the chisel snd lige, Dovemoy’ cntogoreally an an of the and lips. vernoy* categorical] assimilates it to the latter. —? - ‘ aw f The glands lie in the median line throughout nearly their whole extent, and form an spenseutly single and conical mass, whose apex occupies the re-entering angle formed by the union of the two branches of the lower maxilla. 4 to Duvernoy, the submaxillary glands are represented by two very small or situated behind the preceding. Their existence, however, is far from being _ general ; for among common , the Turkey was the only bird in which Duvernoy _ observed these submaxillary glands. - “*.F. (Fig. 221, 2).—This cavity is not distinct from the mouth, the soft palate being entirely absent in birds. On its superior wall may be remarked the guttural oritice < ‘the nasal cavities : a longitudinal slit divided into two by the inferior border of the _ yomer. Below is another less extensive slit, the entrance to the larynx, and which is remarkable for the complete absence of the epiglottidean operculum, (Esopwacus.—T his canal is distinguished by its enormous calibre and great expansi- bility. Its walls are very thin, and contain in their substance lenticular glands, easily seen _ in an inflated cesophagus, in consequence of the tenuity and transparency of its 222 hs igin, the cesophageal canal is not separated from the pharynx by any on; in its course it lies alongside the long muscle of the neck, and the trachea ; extremity is inserted into the first compartment of the stomach, or succentric alter entering the thorax and passing above the origin of the bronchi, Ie ‘almipeds, the cesophagus is dilated in its cervical portion in such a manner as to form, when its walls are distended, a long fusiform cavity. 1 § Anatomie der Hausvogel.’ Berlin, 1849. : * Cuvier. ‘Anatomie Comparée, 2nd Edition. Paris, 1836. . 2F: SS 436 THE DIGESTIVE APPARATUS IN BIRDS. Fig. 221. The abdominal muscles have been removed, as well as the sternum, heart, trachea, the greater portion of the neck, and all the head except the lower jaw, which has been turned back toshow the tongue, the pharynx, and the entrance to the larynx. ; The left lobe of the liver, succentric ven- tricle, gizzard, and in- testinal mass, have been pushed to the right to exhibit the different portions of the alimen- tary canal, and to ex- pose the ovary and ovi- duct, oe ' 1, Tongue; 2, ¥ 3, First portion of the - cesophagus; 4, 3 5, Second portion of the esophagus; 6, Suecen- tric ventricle; 7, Giz- zard; 8, Origin of the duodenum; 9, First branch of the duodenal flexure; 10, Second branch of the same; 11, Origin of the float- ing portion of the small intestine; 12, Small intestine; 12’,Terminal portion of this intestine, flanked on each side by the two ceca (re- garded as the analogue of the colon of mam- mals); 13, 13, Free extremities of the cax- cums; 14, Insertion of these two culs-de-sac into the intestinal tube; 15, Rectum; 16, Cloaca; 17, Anus; 18, Mesentery; 19, Left lobe of the liver; 20, Right lobe; 21, Gall- bladder; 22, Insertion of the pancreatic and biliary ducts; the two pancreatic ducts are the anteriormost, the cho- ledic or hepatic is in the middle, and the cystic duct is posterior; 23, Pancreas; 24, Dia- phragmatic aspect of the lung; 25, Ovary (in a state of atrophy); GENERAL VIEW OF THE DIGESTIVE APPARATUS OF A FOWL. 26, Oviduct. - >. ="? "ees ca oF ie & & a . Se Ae THE DIGESTIVE APPARATUS IN BIRDs. 437 . - & In Gallinacx (Fig. 221, 3, 4, 5), this dilatation does not exist; but the @sopl agus (a3 presents in its course, and immediately before entering tle chest, an ovoid membranous ro’ named the crop (or ingluvies.) In the cesophagus of these birds, then, we find " distinct sections, joined end to end—one superior er cervical, the other inferior or = on the limit of which is the crop. The latter does not differ in its structure a the cesophagus, and is a tempvrury reservoir for the food swa!lowed by the animal < ‘its meal, and where it is softened by being impregnated with a certain quantity of fluid; after which it is passed into the succentric ventricle by the contractions of the external membrane of the crop, aided by a wide subcutaneous cervical musele which _ covers that reservoir. ___In Pigeons, the crop is also present ; but it is divided into two lateral pouches, and exhibits glandular eminences towards the common inferior opening of these sacs into the ee .. “Otherwise, singular changes are observed in tlie apparent structure of its walls in the male as well as in the female, during incubation, or during the tirst weeks _ after hatching.” (Hunter was the first to observe this :—* Observations on Certain Parts of the Animal Economy,’ London, 1792). “ At this period, the membranes of the crop ‘become thickened; the vessels, more numerous and more apparent, are redder, aud the ____ glands more developed. The internal surface is divided by folds or ridges, which cross -__ each other, and form triangular meshes ; while an apparently milky fluid is poured out from the secretory pores into the vate hes the crop. Pigeons cxclusively nourish their __-—s«- young with this fluid during the first t days of their existence.” ! * Sromacu —The stomach presents numerous variations in birds. Its simplest form is z seen in the heron, pelican, petrels, ete., where it is a single sac provided with a thick zone of glands around the entrance of the cesophagus, which secrete the gastric juice. But in the majority of the other pt aud particularly in our domesticated birds, the disposition of the stomach is modified and complicated ; the glandular zone destined for the gastric secretion forms a special compartment—the succentric ventricle, and this is followed by a second reseryoir—the gizzard, which is remarkable for the strong muscular constitution of its walls. The first is also named the glandular stomach, and the second muscular stomach. Glandular stomach, or succentrice ventricle (proventriculus) (Fig. 221, 6)—This is an ovoid sac in the median plane of the body, between the two lobes of the liver, and beneath aorta. Its anterior extremity receives the insertion of the cesophagus; tlie aga is continued by the gizzard. The volume of this stomach is inconsiderable, and = eayity is very narrow; the aliment does not accumulate in it, but merely passes carrying with it the acid juice which afterwards dissolves its prot: in elements. Its walls have three tunics ; an external or peritoneal; a middle, formed of white muscular fibres, inuous with those of the esophagus; and an internal, of a mucous nature, per- forated by orifices for the passage of the gastric juice. These are small cylinders placed perpendicularly to the surface of the stomach, closely laid against one another, like the g . glands of Lieberkiihn, and contained in the cellular layer uniting the inner - te the mts tunic. The glandular structure of this receptacle sufficiently demonstrates that it should be assimilated to the right sac of the stomach in Solipeds, and therefore must be as the true stomach. or muscular stomach (ventriculus bulbosus) (Fig. 221, 7).—Much more yolu- minous than the preceding, this stomach is oval in form, depressed on each side, and situated behind the liver, being partly covered by the lateral lobes of that gland. Above, _ and tothe right, and at a short distance from each otler, are seen the insertion of the _ guecentric yentricle and the origin of the duodenum. ‘The cavity of the gizzard always contains food mixed with a large quantity of silicious pebbles, whose use will be indicated “This viscera is com of the three tunics which form the walls of all the abdominal reservoirs. The internal, or mucous, is distinguished by the thickness and _ extraordinary induration of its epidermic layer, which presents nearly all the characters of tissne, and is so easily detached from the mucous choiium that it is often Tega asa special membrane. On the adherent face of this corium are applied two powerful red muscles—a superior and inferior, cecupying the borders of the organ, and whose fibres, disposed in flexures, pass from side to side, and are inserted into a strong, Dacrous aponeurosis on the lateral surfaces of the organ. Outside this contractile ‘apparatus is a thin peritoneal envelope. The is the triturating apparatus ofbirds. When the aliment reaches its cavity it has not yet submitted to any disaggregation, but here it meets with all the conditions ' Duvernoy. *Legous d' Anatomie Comparée de G. Cuvier’ 2nd Edition, - rr —— 438 THE DIGESTIVE APPARATUS IN BIRDS. indispensable to the accomplishment of this act: two energetic compressor m corneous layer spread over the internal surface of the viscera, giving to it the necessary to resist the enormous pressure exercised on its contents; and ilic pebbles—veritable artificial teeth—which an admirable instinct eauses birds to s and between which, by the efforts of the triturating muscles, the food is bruised. triturating action of the gizzard is only effected in birds fed on hard coriaceous eliment,’ such as the various kind of grain. It would be useless in birds of prey, in whieh the — two gizzard muscles are replaced by a thin fleshy membrane of uniform thickness; showing that the presence of these muscles is subordinate to the kind of alimentation. © Inrestrne.— The length of the intestine varies, as in Mammals, according to the nature of the food: very short in birds of prey, it is notably elongated in : and grunivorous birds. Its diameter is nearly uniform Chesapinek its ae und it is difficult to <—eee iv birds the ee marae Aone, — intestine a of Mammalia. It begins by a portion curved in a loop, which represents duodenum, and whose two branches, lying side by side, are parallel to each other like the colic s sta flexure of Solipeds. Fixed by a short mesenteric um to the colon, this part of the intestine includes the pancreas between its two branches. Its curvature floats freely in in “Ss the pelvic portion of the abdominal cavity (fig. 221, 8, 9, 10). 2 To the duodenal loop succeed convolutions suspended to the sublumbar bya long mesentery, and which are rolled up into a single mass, elongated from pe behind, occupying a middle position between the air sacs of the abdominal Ps - The analogy existing between this mass of convolutions, anil the floating wat add of th small intestine of Mammals, does not require demonstration (fig. 221, 11, 1 = 4 gf The terminal part of this floating intestine lies beside the duodenal taote ant is a | flanked by the two appendages disposed like cwca. ‘Yhese, scarcely marked in the “5 Pigeon by two small t ahencles placed on the track of the intestinal tube,do not measure = Jess than from six to ten inches in the other domesticated birds; they are two narrow — culs-de-sac, slightly club-shaped at their closed extremities, which are free and directed — ¥ towards the origin of the intestine, while the other extremity opens into the intestinal — canal near the anus. There are always alimentary matters in these sacs, these introduced, in following a retrograde course, by the same almo-t unknown mechanisin which presides over the accumulation of spermatic fluid in the vesicule seminales. Ac- as . the foetus, and are gradually hollowed in the thickness of the bones whieh a concur to form them. They increase during the animal’s lifetime, by the thinning of the bony plates inclosing or partitioning them, and particularly _ by the growth of the superior molar teeth, whose roots project into these cavities. The formation of the inferior maxillary sinus is more tardy than the others ; though it is not so late as seven or eight years,as the majority of = Veterinary Anatomists have asserted. M.Goubaux has proved thatthesinusis __ already present at six.months old; and in a head which has been for several years in the museum of the Lyons School, and which belonged toa foalof very small stature, about a year old, this sinus is seen, in its external part, _ to be already 14 inches in depth, and 8-10ths of an inch in width. <<. Functions or THe Srnvuses.— Have the sinuses or diverticuli of the nasal cavities the same uses as these cavities? It is probable, although not absolutely certain. There is nothing to prove that they have anything todo with respiration or olfaction ; and it would seem that their exclusivefunction _ is to give increased volume to the head without increasing its weight,and in this way to furnish wide surfaces of insertion for the muscles attached __ to this bony region—these cavities being all the more ample as the muscles _ are large and numerous. ss DIFFERENTIAL CHARACTERS OF THE NASAL CAVITIES IN OTHER THAN SOLIPED ANIMALS, 1. Nostrils —In the Oz, the nostrils, placed on each side of the muffle, are narrower and less movable than in the Horse. (The superior extremity of the ala is not horizontal; the inferior is divided into two branches.) = In the J’ig, the end of the nose constitutes the snout (rostrum suis), whose anterior surface, plane and orbicular, shows the external orifices of the nostrils. This snout,a veritable tactile organ employed by the animal to dig up the ground, is covered bya dark-coloured skin, kept damp by a humid secretion, like the muffle of the Ox. It He. — for a base the scooping-bone, a particular piece situated at the extremity of the nasal septum, and enveloped by a layer of cartilage which extends around the nostrils. It is. easy to distinguish two symmetrical halves in this bone, which evidently represent the two cartilaginous pieces in the nose of Solipeds. In the Dog, the end of the nose forms a salient region, which is 1onghened, naked, usually dark-coloured, damp, and sometimes divided by a median groove; in this region ‘ the nostrils are pierced, their form resembling two commas opposed to each other by convexities, The cartilaginous framework sustaining these orifices is not com: separate pieces, but is only a dependance of the median septum and the appendages of __ the turbinated bones. a “ry The same considerations apply to the nostrils of the Cat, with the exception of the colour of the integument, which is nearly always of a rosy hue, like the mucous surfaces. __ 2. Nasal Cavities.—The nasal fosse of the Oz, Sheep, and Goat are distinguished by a the presence of a third turbinated bone—the olfactory antrum, und by the communication a existing between them, posteriorly, above the inferior border of the vomer. We have already seen that in these animals, as in those yet to be mentioned, the canal of Jacubson , completely traverses the palatine arch. In tle Pig, the nasal fosse are long and narrow. They are, on the contrary, very short in the Dog and Cat, and the internal cells of the turbinated bones, remarkable —__ for their number and complexity, all communicate with the proper nasal fosse, withou ar coneurring in the formation of the sinuses. — 3. Sinuses.—In the Oz, the frontal sinuses are prolonged into the bony cores which = support the horns, and into the parietal and occipital bones; they therefore enyelop,in a most complete manner, the anterior and superior part of the cranium, and form a double wall to this bony receptacle. They are extremely diverticulated, and do net communicate with those of the great maxillary bones. They usually open, on each side, a into the nasal cavities by four apertures pierced at the base of the great ethmoidal cell, __ According to Girard, three of these orifices lead to special compartments, isolated from one another, and grouped around the orbit ; in consequence of which these diverticnli of —__ the frontal sinuses are designated the orbital sinuses, Orn: This author has denied the presence of sphenoidal sinuses ; but they exist, although small, and are in communication with the preceding. ® THE LARYNX. 449 _ * The sinus of the great ethmoidal cell comports itself as in the Horse. } There is only one pair of mazillary sinuses, which are very large, and partitioned into ____ two compartments by a plate of bone, that bears at its superior border the supermaxillo- :. ‘dental canal, like the superior maxillary sinus of Solipeds. The external or maxillary : x aber is prolonged into the lachrymal protuberance; the internal occupies the fro. of the palatine arch. A wide orifice at the base of the maxillary turbinated ___ bone affords a communication between this sinus and the nasal fossa. - In the Sheep and Goat, there exists a similar arrangement of the sinuses of the head ; but these cavities are much less spacious than in the Ox; the frontal sinus, in ular, does not extend beyond the superior border of the frontal bone. - In the Pig, these latter sinuses are prolonged into the parietal bones; though ar are far from offering the same extent as in the smaller Ruminants. It is the same wi the others; they present an arrangement analogous to those of the Sheep and Goat. Tn the Dog and Cat, there are only, on each side a maxillary and a frontal sinus. ” The first scarcely merits notice; and the second, a little more developed, opens into the nasal cavity by means of a small aperture situated near the middle septum of the two Larreaenne that the Ca ha il ly, th da =f yh states that the Carnivora haye no maxillary sinus ; consequently, the sphenoidal sinus communicates below with the nasal fossz.) “aie 7 5 COMPARISON OF THE NASAL CAVITIES IN MAN WITH THOSE OF ANIMALS. The external orifices of the nasal cavities of Man are called nostrils ; these are flattened transversely, and prolonged in front of the lobule of the nose; their external face or ala is concave and moyable. They are lined internally by a membrane that holds a middle eo between the skin and mucous membranes ; it has a number of little hairs, called isse. The cavities or nasal fossx offer nothing particular ; as in animals, they show a superior, ‘middle, and inferior meatus. On their floor, in front, is seen the superior orifice of the incisive foramen, which corresponds to the commencement of Jacobson’s canal. The pituitary membrane has a squamous epithelinm in its olfactory, as on its Scbneiderian — At the bottom of the nasal cavities and the upper part of the pharynx, is a of diverticulum named the posterior nares; it has been already alluded to when ‘speaking of the pharynx. ? ; ; . The sinuses are : 1, The sphenoidal sinus and the posterior ethmoidal cells, that open beneath the roof of the fosse; 2, The middle ethmoidal cells, opening into the superior meatus; 3, The anterior ethmoidal cells, and frontal and maxillary sinuses, communicating with the middle meatus, All these sinuses have a proper communicating orifice with the nasal cavities. THE AIR TUBE SUCCEEDING THE NASAL CAVITIES, This single tube comprises: the /arynx, which commences the trachea ; the latter forms the body or middle portion, the bronchie terminating it. 1. Laryne. (Figs. 227, 228, 229.) a -—l. Make a longitudinal section of the head, in order to study the wal disposition of the larynx (Fig. 224). 2. Isolate the cartilages, to examine ; external conformation. 3. Remove the muscles from a third larynx, to show the mode of articulation of the various cartilages ( Figs. 227, 228). 4. Prepare the muscles in conformity with the indications furnished by a glance at figure 229. 5. Remove a larynx as y as ible, +o as not to injure the walls of the pharynx, in order to study “the interior of the organ, and especially its pharyngeal opening. Form—Situation.—'The larynx forms a very short canal, which gives passage to the air during respiration, and is at the same time the organ of the voice. ¢ It isa cartilaginous box, depressed on each side, and open from one end to the other : the anterior orifice being situated at the bottom of the pharyngeal a Sogn the posterior continuous with the trachea. 5; is apparatus, situated in the intermaxillary space, is suspended between the two cornua of the os hyoides, and fixed to the extremities of these appendages by one of its constituent pieces. It serves to support the 264 450 THE RESPIRATORY APPARATUS IN MAMMALIA, pharynx, and by means of the walls of the latter is attached to the cir- cumference of the posterior openings of the nasal cavities, In order to facilitate description, this brief notice of its form, situation, general relations, and mode of attachment will be followed by a notice of its structure; afterwards, the study of its external and internal surfaces will receive attention. Srrvucture or THe Larynx.—lIt comprises in its structure: 1, A carti- laginous framework, composed of five pieces; 2, Muscles which move these pieces; 8, A mucous membrane spread over the inner surface of the organ ; 4, Vessels and nerves. -. 1. Cartilaginous framework of the larynx.—In this we find: three single median cartilages, the cricoid, thyroid, and epiglottis; and two lateral cartilages, the arytenoid. All are movable one upon the other. Cricorp Cartinace.—This cartilage, as its name indicates (xpixos, dos, like a ring), is exactly like a ring with a bezel looking upwards. Depressed on each side, but all the less as the animal has its respiratory apparatus well developed, this ring offers two faces, and two borders or circumferences. The internal face is smooth and covered by mucous membrane. The external face is provided, in the middle of the widened portion forming the bezel with a little eminence more or less prominent, elongated in the form of a crest, and separating the two posterior crico-arytenoid muscles, to which it gives attachment, from each other. On the sides of this bezel are two small, articular, concave facets, which correspond to the branches of the thyroid cartilage. Nothing remarkable is to be noted for the remainder of the extent of this face. The superior circumference, comprised laterally between the two branches of the thyroid cartilage, is hollowed out in the narrow part opposite the bezel, where its shows two lateral convex articular facets for articulation with the arytenoid cartilages. The inferior circwmference responds to the first ring of the trachea; it offers a small notch, often double, on the middle of the © bezel. Tuyromw Cartmace (Oupeds, sides of the trachea, Their secretion is: poured out upon the free surface of the mucous membrane, to lubricate and protect it.) Vessels and nerves.—The small arteries emanating from the vessels in the vicinity of the trachea—as the carotid and the collateral branches 460 THE RESPIRATORY APPARATUS IN MAMMALIA. * = of the brachial arteries—supply it with blood. Its neries come from the recurrent ; they show small ganglia on their track. i Functions.—Except as a tube for the passage of the inspired and expired air, the trachea performs no other function. — . a | 83. The Bronchi. (Fig. 232.) a Preparation.—After removing the lung from the thoracic cavity, it is filled with water by fixing the trachea to a water-tap. The bronchi may then be dissected by tearing and triturating the pulmonary tissue. : Each of the two bronchi—the terminal branches of the trachea—resembles a tree imbedded in the substance of the lung, and sending out a multitude of branches, aa BRONCHIAL TUBE, with its Bronchules and Ultimate Ramifications (natural size), Disposition.—At a short distance from their origin, the bronchi enter the lobes of the lung, and pass backwards and outwards towards the superior part of the base of the organ, giving off in their course large collateral branches until they themselves are expended. These branches originate alternately above, within, below, and outwards; and thus extend - in every direction. The first forms an obtuse angle with the principal trunk, and is directed forwards, to ramify in the anterior lobule of the lung ; the others are detached at an angle more or less acute. All are subdivided into gradually-decreasing branches, which soon become of a capillary diameter, and finally open into the pulmonary air-cells. (See Srrvorure or THE Lunes.) / THE TRACHEA. 461 Form.—The bronchial tubes are not flattened like the trachea; a transverse section shows them to be regularly cylindrical. Volume.—The left bronchus is always smaller than the right, and both are much inferior in volume to the aggregate of their respective branches. .—Each bronchus enters the pulmonary lobe along with the blood-vessels, which with it forms what is called the root of the lung. The divisions of this arborescent trunk are accompanied by the bronchial artery, vein, and nerves, which ramify in the same manner. Near their origin, the bronchi are related to the bronchial glands, above which, and to the left side, passes the cesophagus. Srrvorvre —The structure of the bronchial tubes resembles that of the trachea ; their walls being formed by a cartilaginous framework, a muscular layer, mucous membrane, and vessels and nerves. Cartilages of the bronchi.—These only exist in tubes of a certain calibre, the minute passages being deprived of them, and having only membranous walls. As in the trachea, this framework includes, for each tube, a series of transverse rings joined border to border; though these are no longer formed of a single arciform piece, but cach results from the union of several lozenge-shaped pieces whose extremities overlap, and which are united to each other, like the cartilaginous segments of the neighbouring rings, by means of cellular layers, and also by the membranes spread over their internal surface. Muscular layer.—Extended in a very thin continuous layer over the entire inner surface of the cartilaginous rings, this as disappears in the smallest bronchial tubes. Mucous membrane.—This membrane is dis- tinguished from that of the trachea by its great sensibility; it alone constitutes the walls of the terminal bronchial divisions. (When the cartilages terminate, the tubes are wholly mem- branous, and the fibrous coat and longitudinal elastic fibres are continued into the ultimate ramifications of the bronchi#, The muscular coat is disposed in the form of a continuous layer of annular fibres, and may be traced upon the smallest tubes; it is composed of the un- striped variety of muscular fibre.) vous branches distributed in the tisiue of tho “VCS MEXURANS OF & mod bronchial tubes come from the satellite vessels premade: A era aie and nerves of these tubes—the bronchial arteries, veins, and nerves. ‘lhe lymphatics pass to the bronchial glands. DIFFERENTIAL CHARACTERS IN THE AIR-TUBE SUCCEEDING THE NASAL CAVITIES IN OTHER THAN SOLIPED ANIMALS, Rouminants.—In the Oz, Sheep, and Goat, the interior of the larynz is simpler than in the Horse, and the lateral ventricles and vocal cords vit Imost effaced. ‘The most important differences in its various pieces are as follows: 1, The thyroid cartilage has no anterior appendices, but is provided, posteriorly, with ag considerable prolongations that articulate with the cricoid cartilage \it has no excavation between the two wings, and is formed by a single piece; its inner face, in the middle, near the lower border, has a small fossette to which a round and very salient tube rosity on the external faee corres- mds); 2, The upper border of the cricoid is not notched in front (neither is the bezel on its lower border) ; 3, The epigluttis is wider, but less acute, than in Solipeds (Leyh says it 462 THE RESPIRATORY APPARATUS IN MAMMALIA. is less extensive, but thicker); 4, A hyo-epiglottidean muscle bifid at its origin. (There is no aryteno-epiglottidean ligament.) The trachea of these animals does not offer any im t differences, The last ring is not so developed as in the Horse, and the tube detaches a aha: ee toa lobe of the lung which does not exist in Solipeds. (The rings of the mi ion are proportionally nariow, and their extremities meet behind and form a salient ridge.) 1¢.—The larynz of the Pig is remarkable for its great mobility, suspended as it is to the hyoid cornua by the base of a very developed epiglottis, rather than by the wings of the thyroid cartilage. “There are wide, shallow, lateral ventricles, which have a small oblong sinus that ascends between the thyroid cartilage and the mucous membrane. These ventricles are not surrounded by the thyro-arytenoideus muscle, which is small and undivided; above and outwardly, they are margined by a thick cord—a kind of superior vocal cord. considered by Duges as acting with the ventricles to modify the deep grunting sounds.”! (Instead of a tuberosity on the external face of the thyroid cartilage, there is a median crest, and its inferior border has a small point. The cricoid appears to be drawn downwards and backwards, and its lower border is very prominent in the middle, and articulates with one or two small cartilaginous plates w have been sometimes wrongly described as belonging to the proper cartilages of the larynx. The antero-superior angles of the arytenoid cartilages are united to a small cartilaginou: piece which prolongs them ; their external face has a spine, and the internal a 3 are separate by a small pisiform body called the * interarticular cartilage.”) The trachea of this animal resembles that of Ruminants, (It has about thirty rings, “a and has three bronchi.) Carnivora.—The larynx of the Dog and Cat is very like that of the Horse. In proportion, the epiglottis is shorter, wider at the base, and more triangular than in the other species; the lateral ventricles are shallow. (There is an interarticular as in the Pig; there is no sub-epiglottidean ventricle, and the vocal cords appear to be nearer each other. The trachea has about forty-two rings, whose extremities do not meet ; the between them is less in the Cat than the Dog.) The larynx and trachea of Man will be compared with that of animals when we come to describe the lungs. THE THORAX. (Figs. 230, 234.) The thorax, also called the thoracie or pectoral cavity, lodges not only the lungs, but also the heart and the large versels that spring from or pass to that organ, with a portion of the cesophagus and trachea, as well as nerves, which are as remarkable for their number as their physiological importance. Situation.—We have seen that the thorax has for its base the bony cage formed by the ribs, sternum, and bodies of the dorsal vertebrae. Suspended beneath the middle portion of the spine, this cage is transformed into a closed cavity by the intercostal muscles, which fill the spaces between the ribs ; and by the diaphragm, that vast oblique partition which separates the thorax from the abdomen. Internal conformation.—Considered as a whole, the thoracic cavity represents a hollow cone placed horizontally, depressed on each side, and particularly in front towards the summit; with its base, formed by the diaphragm, cut very obliquely, in consequence of the direction taken by that muscle. This obliquity of the diaphragm renders the antero-posterior diameter of the cavity much greater above than below; the difference is more than double. The internal surface of this conical cavity may be divided into six regions: a superior, inferior, and two lateral planes, a base, a posterior plane, and a summit. The superior plane presents, on the middle line, a large projection resulting from the union of the vertebral bodies ; and, laterally, two dee channels—furrows—the vertebro-costal channels. These latter, wider behinc than before, are formed by the superior extremities of the costal arches; 1 Lavocat, ‘ Anatomie des Animaux Domestiques,’ THE THORAX, 463 they lodge the superior border of the pulmonary lobes. The middle jection, or ridge, is comprised between these two lobes. Covered in front y the posterior extremity of the longus colli, this ridge responds, for the remainder of its extent, to the posterior aorta, the thoracic canal, and the vena azygos; on its sides are seen the subdorsal branches of the great sympathetic nerve. The inferior plane, much shorter than the preceding, is, like it, narrower in front than behind ; it has for a base the superior face of the sternum, the sternal cartilages, and the triangularis sterni muscle. Posteriorly, it gives attachment to the fibrous sac containing the heart. Fig. 234, THE PECTORAL CAVITY AND MEDIASTINUM, WITH THE COURSE OF THE TRACHEA AND (ESOPHAGUS. A, Anterior mediastinum; B, Posterior mediastinum; c, The heart and wees dium in the middle part of the mediastinum; p, Diaphragm; §, Trachea; F, (sophagus, The lateral planes, more extensive than the other two, are concave in both their diameters. Formed by the internal face of the ribs and the deep intercostal muscles, they are in contact with the external face of the lung. The base, or posterior plane, formed by the convex face of the diaphragm, is circumscribed on its exterior contour by the circle of asternal carti and by the last rib. In it we see the three openings which traverse the diaphragmatic septum. ; The summit, or entrance of the thorax, is an oval opening, elongated vertically, comprised between the two first ribs and the longus colli muscle, and which is partly obstructed by an enormous collection of lymphatic glands; through this opening passes the trachea, esophagus, the axillary and carotid arteries, the anterior vena cava, and the pneumogastric, great sympathetic, inferior laryngeal, and diaphragmatic nerves. 464 THE RESPIRATORY APPARATUS IN MAMMALIA, Such is the thoracic cavity. Like the abdomen, it is provided with a serous lining, which remains to be examined. Tue Prxevur%.—The serous lining of the thorax comprises two distinct membranes, designated as the pleure, constituting two sacs placed one against the other in the median plane, and forming a septum named the mediastinum, which divides the thoracic cavity into two lateral compart- ments. Each pleura, therefore, covers one of the external or costal walls of the thorax, and the ee I moiety of the diaphragm; it is afterwards reflected in the vertical and antero-posterior plane of the cavity, to concur in the formation of the mediastinum, whence it is carried over the lung. This arrangement exhibits the pleura in four portions: a costal, diaphragmatic, mediastinal, together representing the parietal layer of the membrane, and a pulmonary or visceral portion. . The costal pleura is applied to the inner face of the ribs and the internal intercostal muscles. Strengthened on its adherent face, at each intercostal space, by a lamina of yellow elastic tissue, this membrane responds, by its free face, to the external plane of the lung, with which it does nof, in a normal condition, contract any adhesions, It is continued, posteriorly, — with the diaphragmatic layer; in front, above, and below, with the medias- tinal pleura. . The diuphragmatic pleura adheres somewhat loosely to the fleshy portion of the muscle, but the union is more intimate on the aponeurotie portion. This layer is contiguous, by its free face, with the base of the lung; it is confounded with the mediastinum by the internal part of its periphery. The mediastinal pleura is placed, by its adherent face, against that of the opposite side, and in this way produces the middle septum which divides the thoracic cavity into two portions. Several organs are comprised between the two layers of this partition, but most important of all is the heart. In Veterinary Anatomy, that part of the septum in front of this organ is named the anterior mediastinum; the appellation of posterior mediastinum being reserved for the portion situated bebind it. These terms have not the same signification as in human anatomy, though they are retained here to prevent misunderstanding. The anterior mediastinum, thicker than the posterior, but much less extensive, contains, superiorly, the trachea, cesophagus, the anterior aorta and its divisions, the anterior. vena cava, thoracic duct, the cardiac, pneumo- gastric, recurrent, and diaphragmatic nerves; it also includes the thymus gland in the fetus and young animal. The posterior mediastinum is incomparably narrower below than above, in consequence of the oblique position of the diaphragm. Its inferior part, always deviated to the left, is extremely thin, and perforated by small openings, which give it the appearance of fine lace-work. Traversed altogether superiorly by the pos- terior aorta, the vena azygos, and the thoracic duct, this mediastinum gives passage, a little lower between its layers, to the esophagus, the cesophageal branches of the pneumogastric nerves, and to the left diaphragmatic nerve. It is these layers of this mediastinum which pass to the lung to constitute the pulmonary pleura, in becoming reflected above and below, in a hori- zontal line extending from the root of the pulmonary lobe to the anterior face of the diaphragm. The pulmonary or visceral pleura, a continuation, as has been said, of the mediastinal pleura, is in contact, by its free face, with the parietal layer of the membrane. Its deep face adheres intimately, in Solipeds, to the proper tissue of the lungs. THE THORAX. 465 Independently of these four serous layers, the right pleura furnishes a special membranous fold, which arises from the inferior wall of the thoracic cavity, and ascends to envelop the posterior vena cava, ‘This fold also sustains the right diaphragmatic nerve. In order to study the various portions of the pleure collectively, with their reciprocal relations, and their connections with the organs contained in the thoracic cavity, we will suppose three transverse sections of this cavity : one passing behind the heart; the other at the roots of the lungs, and dividing the left ventricle of the heart ; the third traversing the anterior mediastinum, a little in front of the right ventricle. If, in the first section (Fig. 235), we take the costal pleura at the point a, and follow it up to b, we will see it folded downwards to form the Fig. 235. Fig. 236. Fie. 237. THEORETICAL SECTIONS OF THE THORACIC CAVITY; INTENDED TO SHOW THE DISPOSITION OF THE PLEURX. mediastinal layer, to be applied to the aorta, ¢, and the wsophagus, d; then reflected at ¢ on the lung, /, enveloping every part of the organ; returning to the point ¢, it leaves the lung, is again reflected to achieve the formation of the mediastinal septum, b g, and finally regains the point it started from. On the right side, with only a slight variation, it has the same arrangement. After being carried from the point a’ to b’, then to «’, and after enveloping the lung, returning to e’, and being reflected in the median plane to the point g, the right pleura leaves the inferior thoracic wall to pass around the posterior vena cava, and come back to a’, its point of departure. The second section, (represented by Fig. 236) shows the pleura arrived at the point b, descending on the root of the lung, ¢, covering that organ and returning to c, and reflected on the pericardium, d, to gain the point a. In the third section (Fig. 237), we see the parietal pleura, a b, without any points of continuity with the visceral pleura, c. It is at the level of this section that the lung forms two perfectly free lobes, which are not attached to the anterior mediastinum. Srrvorure.—Like all the serous membranes, the pleure have a free face covered by a simple tesselated epithelium ; it is perfectly smooth, always in contact with itself, and constantly lubricated by a serous fluid which facilitates the gliding of the lung on the parietes of the thoracie cavity, 2H 466 THE RESPIRATORY APPARATUS IN MAMMALIA, The deep face is united to the subjacent “remap by connéctive ” tissue destitute of fat; the adherence of the visceral pleurw is most intimate, = The pleura has. plexuses of vessels ; one, the subserous, has large ners but a second, the subepithelial, has a closer network. The nerves are from the sympathetic and pneumogastric for the pul- = ‘ monary pleura: from the diaphragmatic and intercostal nerves for hie parietal pleura, eee Founorrons.—The thorax is not a mere receptacle, but, on the contrary, — rs performs a very important part in the act of respiration. We know, in fact, — that it is dilated and contracted by the movements of the diaphragm and the “% . ' ibs (see pp. 142, 248). The lung being applied immediately against the thoracic walls, and never at any time separate from them, follows this cavity = in its movements, dilating in inspiration and contracting in expiration, after 4 a certain quantity of the oxygen of the inspired air has been removed and replaced by an equivalent amount of carbonic acid. The movements of the thorax are, therefore, of capital importance, con-— stituting, as they do, the initial phenomenon of respiration, and med dependent on them all the other acts of this function, x i DIFFERENTIAL CHARACTERS IN THE THORAX IN OTHER THAN SOLIPED ANIMALS, — , In the Oz, the thorax is not so long, particularly in its superior part, as in Solipeds» by reason of the slight obliquity of the diaphragm, and of its mode of attachment to the The total capacity of tLis cavity is also certainly inferior to that of the Horse’s chest, 5 It is the same, though relatively more extensive, in the Sheep, Goat, and Pig; while — the Dog possesses in this respect an incontestable superiority over Solipeds. It is to be noted that all these animals, without exception, are distinguished from the Horse, Ass, - and Mule by the conformation of the posterior mediastinum, In them it is not open in : its lower part, but as solid, thick, and complete there as elsewhere. Therefore it is that the consecutive effusion of pleuritis is readily localised in one of the pleural saes in the : first-named animals, while this localisation is impossible in the second, (Thisisan | important observation, in a pathological point of view.) > | THE LUNG (OR LUNGS), (Figs, 230, 234.) Preparation.—The disposition of the lung in the thoracic cavity is best studied by placing the subject iu the second pesition, opening the chest by excision of the ribs, as in Fig. 234, and inflating the organ by the trachea. To study its external fap = acs be’ removed from the cavity, with the heart and large vessels, and inigene as ore : 7 Situation — General disposition,—This essential organ of respiration 4 is a") spongy viscus, lodged in the thoracic cavity, and divided into two lateral, but independent, moieties, each of which occupies one of the two serous sacs formed by the plure. It is also described as two pulmonary lobes, or two lungs—a right and left, the latter a little less voluminous than the former. Form and Relations.—Together, the lungs affect the outline of the thoracic cavity ; each represents the moiety of a cone, and offers for study : an external and internal face, a base and summit, and a superior, inferior, and — posterior border. The external or costal face is convex (and smooth), and moulded to the external wall of the thorax. The internal, or mediastinal face, forms a vertical plane, separated from the opposite lung by the mediastinum. It shows: 1, An inextensiveanterior part, in contact with the anterior mediastinum ; 2, At the level of the heart, an excavation in which that organ is lodged; 3, Immediately behind this excavation, and a little above it, the root of the lung (hilum-pulmonis ), a fasei- sites * THE LUNGS, 467 culus formed by the air-tubes and pulmnary vessels in entering the viscus ; _ 4, A posterior portion, more extensive than the other two put together, corresponding to the posterior mediastinum, and attached to that septum by _ means of a fold developed around the organ, to form the pulmonary pleura ; this fold constitutes, posteriorly, a small serous ligament (ligamentum latum monis), attached at once to the mediastinum and the posterior face of the phragm. On this portion of the lung are remarked two antero-posterior fissures: one, hollowed near the upper border of the organ, to receive the thoracic aorta; the other situated lower, but not so deep, more marked in the left than the right, and lodging the esophagus. In the right lung this mediastinal face offers a small particular lobule, which is absent in the left. The base, or diaphragmatic face of the lung, cut obliquely from above to below, and before to behind, is concave, and moulded to the anterior face of the diaphragm. On the right lung is seen the posterior face of the small lobule noticed on the inner side, and a deep fissure excavated between it and the principal lobe, for the passage of the posterior vena cava. The summit of the viscus, situated behind the first rib, presents a kind of detached appendix, designated the anterior lobule of the lung. . The superior border, thick, convex, and rounded, is lodged in the vertebro- costal channel or concavity. The inferior, much shorter and thinner, is deeply notched at the level of the heart, and more so at the left than the ight side. The posterior is elliptical, and everywhere circumscribed-by the face of the diaphragm, which it separates from the costal and mediastinal faces. Srrvoerure.—An external serous envelope, proper fundamental tissue, Junctional and nutrient vessels, lymphatics, and nerves: such are the elements which enter into the organisation of the lung. Senovus Envetorr.—This is the pleura pulmonalis already described. has also been described a subserous connective tissue, containing a proportion of elastic fibres ; it invests the entire surface of the lung, and extends between the lobules.) Foypamentat Tissuz.—Physical characters.—The pulmonary tissue in the adult is of a bright rose-colour; it has a deeper hue in the foetus which has not respired. Although soft, it is yet very strong and resisting, and ean with difficulty be torn. Its elasticity is remarkable ; it concurs in the collapse the lung experiences when air is admitted to the pleural sacs. It is very light: plunged in water, if healthy, it floats; this specific lightness ought to be attributed to the air imprisoned in the pulmonary vesicles. This may be proved by what takes place when the lung of a fetus is inflated: heavier than water before that operation, it then becomes lighter, because, notwithstanding all the manipulation that may be employed to expel the air introduced into the pulmonary vesicles, a certain quantity always re- mains. On the other hand, the absolute weight of the lung is relatively more considerable *» the adult than in the fcetus, the first representing 1-30th of the total mason body, while it is only 1-60th in the second. A knowledge o facts may be utilised in determining whether a given lung has belonged to an animal which has respired or has died before birth. If the tissue is plunged in water, this test is called hydrostatic pulmonary docimacy ; if its relative weight is to be ascertained, it is designated pulmonary docimacy by weight. These are the physical characters of the fundamental tissue of the lung; we will now study its anatomical characters. Anatomical characters.—The pulmonary tissue is partitioned ee & great 24H 468 THE RESPIRATORY APPARATUS IN MAMMALIA, number of small polyhedral lobules by septa of connective tissue, which appear to be prolongations of the corium of the external serous membrane, This segmentation into lobules is a common feature in the organisation of the lungs in the mammalia, but it is more readily demonstrated in some than others: not very evident in Solipeds, and less so in the Carnivora, it is well defined in Ruminants and Pachyderms. ; The organisation of these lobules resembles, in a striking manner, that of the salivary lobules. Each receives a small bronchial tube (lobular bronchial tube), which is prolonged into the lobule by several short terminal branches, in which open a certain number of elementary vesicles. In comparing, for the moment, the lung to a gland, it will be seen that this organ should be ranged in the category of racemose glands. To demonstrate the vesicular structure of the lung, it may be inflated and dried, and sections afterwards made to show the pulmonary vesicles. But this procedure has the inconvenience of unduly extending the vesicles, and thinning, and even destroying, their walls. A better method is the following : leave the lung in the intact thoracic cavity ; by the jugular vein, pour into the right side of the heart an injection of very hot tallow, employing a certain amount of force to propel it from the pulmonary artery into the veins; when this injection has cooled, open the thoracic cavity, and take out the lungs. These, being impregnated with solidified fat, do not collapse on contact with the air, and sections made in different directions then exhibit innumerable perfectly-circular porosities, which are the open pulmonary vesicles. : In this way it is easy to demonstrate the presence of the air-cells ; but, in order to conveniently study their arrangement, it is necessary to take a cast of them by means of a solidifiable material introduced by the bronchii, and afterwards destroyed by the maceration of the pulmonary tissue. The Darcet alloy, employed in this manner, often gives very good results. It is then found that the pulmonary vesicles form, in each lobule, saccular dilatations or culs-de-sac, from 1—-70th to 1-200th of an inch in diameter, grouped around the infundibuli, of which they are only diverticuli; these infundibuli communicate with the terminal bronchule of the lobule through the medium of a narrow central cavity, into which they all open. Such are the principal histologic details relative to this im- portant point in the history of the lungs; and it must necessarily be followed by a notice of the structure of the pulmonary vesicles (or air-cells). The pulmonary vesicles comprise, in the organisation of their walls: a proper membrane; epithelium; and capillary vessels. PLAN OF A PUL- 1. The proper membrane is thin and homogeneous ; it MONARY LoBULE. contains the nuclei of connective tissue and elastic fi a, Bronchule termi- and its external face is applied to that of the neighbour- nating in a slight ing vesicles; its internal face is lined by epithelium. pomp edt y Nay 2. The epithelium is simply tesselated, and is com- a Ale of rae posed of extremely thin cells. It is continuous through- westelens out the vesicles, and with that of the terminal bronchule. In a properly-prepared section, the polyhedral cells lining the latter can be seen changing gradually and rapidly into squamous epithelium in the cavity of the lobule, at the entrance to the infundibuli. THE LUNGS. 469 (The minute polygonal cells lining the air or pulmonary vesicles measure from 1-1600th to 1-2250th of an inch in diameter, and from 1-2800th to 1-3800th of an inch in thickness. Between the vesicles is a trabecular tissue, mainly composed of yellow elas- tic with a few muscular fibres, some of which are united with the lining membrane to strength- en it, especially around the apertures of communication be- tween the adjoining air-cells.) 3. Capillary vessels ramify in the walls of the vesicles, and even project on their inner face. (The capillary plexuses are so arranged between the two layers forming the walls of two adjacent cells, as to expose one of their surfaces to each, in order to secure the influence of the air upon them. These networks are so close, that the diameter of the meshes is scarcely so great as that of the capillaries which inclose them.) Fig. 239. \ ] AIR-CELLS OF LUNG, WITH INTERVENING TISSUES. VusseLts.—The lung is a ,g, Epithelium ; 6, Elastic trabecule ; c, Membranous very vascular organ. The nu- merous ramifications it receives wall, with fine elastic fibres. divide into two orders—the functional and the nutritive vessels. Functional vessels of the lung.—We know that the blood returns from all ts of the body by the veins, after osing, along with its bright red colour, the properties which render it fit to maintain the vitality of the tissues. It thus arrives at the right side of the heart, whence it is pro- pelled into the lung, there to be regenerated by mediate contact with the air. It is the pulmonary artery which conveys this fluid into the parenchyma of the organ, and by the pulmonary veins it is carried back to the heart. The artery is at first divided into two branches, which ramify and finally terminate in dense capillary plexuses upon the walls of the air-cells. The veins, innumerable and attenuated at their Fig. 240. ARRANGEMENT OF THE CAPILLARIES AROUND THE AIR-CELLS, origin, like the arterial capillaries, terminate in from four to eight principal trunks, which open into the left auricle of the heart. re ; These two orders of vessels, which necessarily participate in the physiolo- 470 THE RESPIRATORY APPARATUS IN MAMMALIA, gical functions of the lung, like the vena porte with the liver, are very properly distinguished from the other arteries or veins of the organ by the designation of functional vessels. But though they are so named, it must not be inferred that they are excluded from all participation in the acts of nutrition. It is now admitted by competent authorities that the blood of these vessels concurs to sustain vitality in the tissue of the lung, in common with the nutritive fluid carried by the arteries and veins now to be described, | Nutrient vessels—By this name is designated the divisions of the bronchial arteries and veins, whose terminal ramifications anastomose with the capillaries of the pulmonary vessels at the ultimate bronchules. Lymphatics.—These vessels are divided into superficial and deep. The first form a network beneath the pleura; the second exist in large numbers around the lobules. They mix together; and terminate in the bronchial glands. (Lymphatics of very small size have been described as commenci in the alveolar spaces, on leaving which they gain a proper coat or in tunic, and are subsequently supplied with valves.) Nerves.—The nervous branches supplied to the tissue of the lung come from the same source as those of the bronchial tubes—the pnewmogastrie and great sympathetic nerves. Their ramifications accompany the pulmonary vessels and bronchie, and they show small ganglia on their course. Funottons.—To know that the lung is the seat of the absorption of oxygen and the expulsion of carbonic acid from. the nutritive fluid— phenomena accompanied by the transformation of the dark into red-coloured blood, and probably of several other metamorphoses yet doubtful or un- known—is the only authentic fact necessary to remember with regard to the functions of this organ. It must be added that the subtle molecular opera- tions from which all these phenomena result, take place in the lung by the mediate contact of the atmosphere introduced into the air-cells during inspiration, with the blood traversing the walls of these cells. With the intimate mechanism of these molecular actions we have nothing to do here, however. Dervetorment.—Although the lung is in a state of inactivity in the foetus, yet it is one of the organs early developed. During the whole period of foetal existence, its lobular texture is much better defined than in the adult, and it then “appears to be formed exactly like a racemose gland. Sections of it prepared for microscopical examination distinctly show the vesicles and their arrangement. We have already made known the differ- ences in colour and density which distinguish the pulmonary tissue of the foetus and that of the adult. It only remains to repeat what has been said as to the slight vascularity of the first, and to note that the blood of the pulmonary artery passes almost entirely into the posterior aorta by the arterial canal (or ductus arteriosus). DIFFERENTIAL CHARACTERS IN THE LUNGS OF OTHER THAN SOLIPED ANIMALS. The lungs of the Oz, Sheep, and Goat are remarkable for the distinctness with which the lobules are defined. They are, in fact, separated by thick layers of cellular tissue, continuous with the internal face of the visceral pleura. (‘These thick septa are rather the interlobular ramifications sent off from the subserous envelope.) Dietrichs, who was the first to draw attention to this peculiarity in the larger Ruminants, has justly remarked that it perfectly explains the altogether special characters of the lesions of pneumonia in these animals. The general figure of the lungs of Ruminants does not differ from that observed in the Horse; the left lung, however, is divided into two lobes, and the right into four, THE LUNGS. 471 of which one, an anterior, is curved in front of the heart. The annexed figure shows this peculiarity. In the Pig, the ep, errand themselves like those of Ruminants. Tn the Dog and , there is no well- marked fissure in either lung towards the heart, which causes that organ to be almost completely enveloped by pulmonary tissue. The left lung has three iobes, and the right four, separated from one another by deep furrows, which are generally prolonged. to the root. ‘The lobules are small, very close, and the pulmonary tissue is exceedingly compact. (The pulmonary vesicles are pro- portionately larger than in Ruminants.) COMPARISON OF THE LARYNX, TRACHEA, AND LUNGS OF MAN WITH THOSE OF ANIMALS, 1. Larynz.—The human la is pro- portionally shorter and wider than that of animals. The principal cartilages are those which have been already studied; -but. there are, besides, small cartilaginous bodies, to which special names have been given: these are the cartilages of Santorini and of Wris- berg. The facets on the cricoid for articu- lation with the thyroid are placed on the small cornua detached from the external face of the cartilage. ‘The thyroid is wide, and protects the anterior face of the larynx; the angle formed by the alw, which is more marked in the male than the female, is very rominent, and is named the pomum Adami. Che epiglottis is short, broad in its middle, and rounded at its summit, something like that of the Carnivora. .The muscles are the same in number and disposition as in these animals; but there is distinguished an oblique arytenoideus—a fasciculus of the arytenoid, which crosses its fellow to form an X in passing from the upper border of one arytenvid cartilage to the lower border of the other. 1, Right ventricle; 2, Left ventricle; 8, Right auricle; 4, Left auricle ; 5, Pulmonary artery; 6, Right pulmonary artery; 7, Left pul- monary artery; 8, Ligament of ductus arteriosus; 9, Arch of aorta; 10, Superior vena cava; 11, Arteria innominata ; 12, Right subclavian vein, with the artery behind it; 13, Right common carotid artery and vein; 14, Left vena innominata; 15, Left caro- tid artery and vein; 16, Left subclavian vein and artery; 17, Trachea; 18, Right bronchus; 19, Left bronchus; 20, 20, Pul- monary veins; 21, Superior lobe of right lung; 22, Middle lobe ; 23, Inferior lobe; 24, Superior lobe of left lung; 25, Inferior Fig. 241. LUNG OF THE SHEEP}; INFERIOR VIEW. 1, Right lung; 2, Left lung; 3, Trachea; 4, Heart; 5, Carotid arteries; 6, Posterior vena caya. lobe. HUMAN LUNGS AND HEART; FRONT VIEW, 472 THE RESPIRATORY APPARATUS IN MAMMALTA,~ Internally, the human larynx has no subepiglottic or subarytencid sinus like that of Solipeds, though it has lateral, or Morgagni’s, ventricles that uscend a little to the outside ot of the superior vocal cords. : 2. Trachea.—8. Bronchi.—There is little difference to be remarked in these. The trachea is about four inches long and about one inch wide, and is composed of about twenty C-shaped rings, which are closely united, as in animals. It is situated in the « median plane, in the upper part of the neck, where it is embraced by the lobes of the thyroid gland; at its entrance into the chest it deviates slightly to the right. The two short canals between its lower extremity and the lungs are the bronchi; the right bronchus is the shortest and widest, and has an almost horizontal direction, ente the right lung at the fourth dorsal vertebra; the left is longer and less yoluminous, reaches the corresponding lung at the fifth vertebra. 4. Lungs—The lungs weigh about forty ounces. As in all animals, the right is more voluminous than the left, and is divided into three lobes; the latter has only two, The inferior vena cava is not surrounded by pulmonary tissue; the principal lobes are partitioned into lobules, which are visible on the surface, and on the limits of which are deposited, only in the adult, a notable quantity of pigmentary matter, that gives the lungs the appearance of a chess-board. There is nothing to be said respecting their internal conformation and structure. THE GLANDIFORM BODIES CONNECTED WITH THE RESPIRATORY APPARATUS. 1. Thyroid Body (or Gland). The thyroid gland, or body, is composed of two oval lobes of a reddish- brown colour, and is situated close to, and behind, the larynx, beside the two first rings of the trachea. These two lobes, distinguished as right and left, appear at first sight to be perfectly independent ; but a less superficial examination shows them to be united by an intermediate portion (the isthmus), which passes across the anterior face of the trachea. Each lobe of the thyroid body corresponds, inwardly, to that tube ; outwardly, it is covered by the subscapulo-hyoid muscle. | f Srructure.—The thyroid body ee? Br is composed of a fibrous envelope, and a proper tissue or parenchyma, The fibrous envelope is composed of slender, but strong connective tissue; it sends from its inner face a large number of thin nu- cleated lamine that intersect each other, forming spaces in which the proper tissue is contained, The parenchyma is divided into lobules, whose presence is mani- fested on the surface of the organ. They are composed of vesicles, the shape and contents of which vary considerably with age and situa- tion. In the foetus, or very young animal, they are round or elli tical, and constituted by a thin RODE OW iaiaitien lana amorphous membrane, lined by a, Connective tissue; b, Basement membrane of polygonal cells with a large nu- the vesicles; c, Epithelial cells. cleus, and containing a granular fluid. In the adult, these vesicles are deformed, and, after being distended, several are confounded together ; GROUP OF GLAND VESICLES FROM THE THYROID THE THYROID AND THYMUS GLANDS. 473 the epithelium is less evident and uniform, the contents have become brown, and hold granules and nuclei in suspension, and, finally, often assume the character of colloid matter in becoming viscous and of a yellow tint. Vessels and nerves.—The thyroid body is remarkable for the relatively enormous volume of its blood-vessels; the arteries chiefly come from the . thyro-laryngeal branch—a collateral of the primitive (or common) carotid Bs y form plexuses on the vesicle walls); the veins pass to the jugular. nervous filaments are from the first and second cervical pairs, with twigs from the sympathetic. It has an abundance of lymphatics. Funotions.—The thyroid is one of the organs classed, in a somewhat arbitrary manner, in the ill-defined category of ductless or blood-vascular glands. Our knowledge of its use is as uncertain at present as in the infancy of anatomical science. So that we can say nothing more on this subject, except that the successive or simultaneous excision of the two ol the Horse do not appear to cause any derangement in the animal’s Neither does the study of its development throw any light on its func- tions. It is certainly relatively larger in the foetus and young animals than in adults; but the difference is not sufficiently marked to authorize us in drawing any physiological inductions therefrom. 2. Thymus Gland. The thymus gland is a transitory organ, only present in the foetus and very young animals, and in its nature closely resembling the thyroid gland. Like it, it is divided into two lateral lobes placed close together in the middle line, under the lower face of the trachea, partly without and partly within the chest, between the two layers of the anterior mediastinum. It is : ted from before to behind, of a whitish colour, and uneven or lobulated on its surface like a salivary gland. Srructure.—It owes its uneven aspect to its lobular structure, for it is effectively reduced by dissection into a multitude of granular lobules, in the centre of which are found vesicular cavities containing a lactescent fluid. The vesicles are larger than those of the thyroid gland, and have for their walls a very thin layer of delicate connective tissue; they are filled by a mass of nuclei. A wide, irregular cavity has been described as existing in the middle of each lobe (reservoir of the thymus), and evidently communicating with the vesicles of the lobules, as it contains a notable quantity of the same milky fluid. This cavity is certainly not present at all periods ; for I have not met with it in two young fcetuses now lying before me as I write. But without dwelling on this particular point, we may notice enormous blood- vessels, lymphatics, and nerves, as complementary elements in the organisa- tion of the gland, whose structure is very similar to that of the proper glands, though differing from them in an important feature—the absence of an excretory duct. Nothing positive is known as to the functions of the thymus gland; it is only certain that they are exclusively related to the development of the young animal, as it generally disappears some months after birth, though it is sometimes found in adult, and even in very aged animals. (Its functions are supposed to be the same as, or analogous to, those of the a, Structurally, the organ may be said to consist of an assemblage of w glandular lobules joined together by connective tissue, each mt i a cavity which opens into a central canal that has no duct, and being lin 47t THE RESPIRATORY APPARATUS. externally by an almost amorphous membrane which divides it into © a or gland-granules. Separate acini are often observed on the main i oe Each lobule is made up of its greyish-white, soft parenchyma composed of free nuclei and small cells, and has a minutely-distributed capillary plexus. Fig. 245, I TORTION. OF THYMUS COURSE AND TERMINATION OF THE ABSORBENT GLAND OF CALF, DUCTS OF THE THYMUS GLAND OF A CALF, UNFOLDED. 1, Internal jugular veins; 2, Superior vena cava; a, Main canal; 2, 3, Thoracic duct, dividing into two branches, Glandular lobules: that again unite before terminating in the root c, Isolated gland of the left jugular vein; 4, The two thymic — granules seated on ducts: that on the left side opening into the © the main canal. thoracic duct, and the right into the root of the corresponding jugular vein. The lymphatics terminate in two large ducts that commence at the upper extremities of the lobes of the gland, the thymic ducts, and pass down- ward to terminate at the junction of the jugular and axillary veins at each side.) DIFFERENTIAL CHARACTERS IN THE GLANDIFORM BODIES ANNEXED TO THE RESPIRATORY } APPARATUS IN OTHER THAN SOLIPED ANIMALS, : The thyroid body, peculiar to Mammals, is more developed in Ruminants, Pachy- derms, and the Carnivora, than in ng A The two lobes are closer together, and often joined by the thyroid isthmus. In the Pig this is very marked, and the gant well merits its name, as it forms a veritable shield in front of the trachea, towa: lower part of the neck. THE RESPIRATORY APPARATUS IN BIRDS. 475 _ The thymus gland in young Ruminants is more voluminous than in the Foal, and is _ situated higher up in the cervical region. (In the Carnivora, it is divided into two branches ; but it is small, and completely lodged between the layers of the anterior mediastinum. It persists for some time after birth, and seldom disappears in less than a year.) (COMPARISON OF THE GLANDIFORM BODIES ANNEXED TO THE RESPIRATORY APPARATUS IN MAN WITH THOSE OF ANIMALS. _ with the isthmus or pyramid, and is attached above to the body of the os hyoides or to _ the thyroid cartilage; it has been named the levator glandulx thyroi _ The thymus gland is composed of two lobes, a right and left, only joined by connective tissue, and having no structural communication. There is a cervical and a _ thoracic portion, the whole extending from the fourth rib as high as the thyroid gland. After birth it continues to enlarge until the end of the second year, and begins to diminish between the eighth and twelfth years.) 4 CHAPTER II. ; THE RESPIRATORY APPARATUS IN BIRDS. Tue organs ing the ira apparatus of birds, offer conditions altogether special, and which have a Scattighie faionse on the mechanism of respiration. The modifications imposed upon the performance of this function will be indicated after an the -yoice of these creatures; it only exists in a rudimentary condition in ultry, however, the last tracheal piece in them being slightly dilated, and showing at the origin of the bronchi a membranous layer, from whose vibration results cries or crowing. Other singular ities belonging to the trachea deserve to be described here, if they were not the exclusive appanage of some wild fowl. We are content to mention the presence of the bony drum found at the terminal extremity of the trachea in the whistling duck, and the remarkable convolutions that tube forms in the breast-bone of a 8 _ The bronchi only show incomplete rings in their structure. They into the lung ’ by its inferior face, towards the union of its anterior and two posterior thirds, When ‘organs in Man and the Mammalia during uterine life, and for some time after birth; are especially remarkable for their restricted volume, which scarcely represents an aehth ode of the thoracic capacity. Their configuration is far removed from the ‘conical form of the lungs in Mammels, and the oval form of the same organs in reptiles ; they are semi-elliptical, and if the two lungs of a Mammal were opposed base to base, 476 THE RESPIRATORY APPARATUS, their likeness would be produced ; to obtain the same results with the lungs of a re optile, it — is necessary to divide them in the direction of their great axis. =< “This shape enables us to distinguish in the lungs of a bird, two facea—an o and concave ; two borders—an external and internal; and two extremities—an and posterior, “'The convex face, also named the costal, or superior face, to the dorsal vertebra, and parked wi the a oe and the ey exactly moulded on the walls of the thorax, and as the ribs protrude on the internal — of these walls, it results that this surface of the lungs is marked by transverse furrows which give it a lobulated aspect ; but these lobes or lobules show nothing pore So those composing the same organ in Mammalia. In that class, the existence of lobes and lobules is an established fact, and is caused by the dichotomous division of the “hg in birds, it is only apparent, and depends on the diminished thickness of the lung each rib. This face, quite imperforate, is covered by a thin layer of a “These reservoirs are: the thoracic sac, situated at the anterior part of the thorax; two cervical ey serk — at Baltes of the neck; ron re wc natic reservoirs, place tween the two dia gms; two posterior diaphragmatic reservoirs, — also between these two diaphragms, Mut behind the preceding; and, lastly, two — abdominal reservoirs, placed against the superior wall of the abdomen. Of these nine reservoirs, the first only is single and symmetrical; the others are pairs, and sin a arranged on each side of the median plane. wet Ee “The thoracic and cervical reservoirs are situated beneath, and in front of, tho Jungle the abdominal reservoirs lie behind these organs, and the four diaphragmatic sacs at | their inferior part and between the preceding; hen-e the denomination of middle reservoirs sometimes applied to the latter, in opposition to the first, which are named the — anterior reservoirs, and to the second, called the posterior reservoirs.” ‘ah ExrerNat ConFORMATION OF THE ResEevorrs.—1l. Thoracic reservoir (Fig. 246, 2).— — “It is situated above the clavicles and the inter-clavicular space, in the cavity pf the — _ thorax, which it extends beyond on each side to the roots of the wings, around the articulation of the shoulder. It is related with: above, the trachea and cesophagus on the middle plane, the lungs and the origin of the cervical reservoirs on the lateral parts; below, with the sternum, the clavicles, and the interclavicular aponeurosis; behind, with the heart and anterior diaphragmatic reservoirs, beneath which it is prolonged by — forming on each a long point ; in front, with the integuments of the neck, whieh raises into a hemisphere in Palmipeds, but which is angularly depressed in other classes; on the sides, with the sternal ribs, the two clavicles, and the membrane uniting them. “The prolongations which arise from the lateral bh sap of these reservoirs, aud cross the walls of the thorax to pass around the articulation of the shoulder, are threein number, and may be distinguished into inferior or sybpectoral, superior or subscapular, — and middle or humeral. ee “The subpectoral prolongation (Fig. 246, d) issues from the thoracie reservoir by an — orifice situated behind the posterior clavicle, and passes beneath the tendon of the great pectoral muscle, where it spreads out as a lenticular cavity. The relations it contracts with that muscle are remarkable: in birds, still more than in Man anda greatnumber __ of quadrupeds, the tendon of the great pectoral is formed of two parts, one direct, the other reflected ; it is between these two portions that this small air-sac is insinuated,and where it forms a very firm connection with them; the effect of which is, that at the moment the great pectoral muscle contracts, it dilates the subjacent cell and draws into it a greater quantity of air. 3 ae “The subscapular and humeral prolongation communicate with the principal reservoir by a common opening placed behind the small adductor muscle of the humerus. After leaving this orifice, the subscapular sac spreads under the scapular and subscapular muscle, which it separates from the ribs and corresponding intercostal muscles; itis __ 5 a more particularly in a longitudinal direction. a ae “The humeral prolongation occupies the axilla ; it is smaller than the preceding, ofa pyramidal form, and opens by its summit into an infundibular fossa, which leads tothe canal of the humerus. eG > “The thoracic reservoir differs from all the others by the extremely numerous pes i - ae 1 What is said relating to these air-sacs is taken from the Memoir of M. Sappey— __ *Recherches Sur Appareil Respiratoire des Oiseaux,’ Paris, 1847, Sian a A * 1S r} ‘cated i PIP. or , ie i, “a : THE RESPIRATORY APPARATUS IN BIRDS. 479 ranoits folds which partition its cavity. The membrane forming it being continued on itself, every organ traversing the thorax becomes the cause of a fold in which it is imprisoned ; and as the thoracic cavity is traversed by the trachea and the cesophagus, the muscles which move the inferior larynx, and the arteries and veins, it will reine soe es how this reservoir should become irregular in consequence of these various partitions, and also why the other wrial sacs situated between the viscera and the walls of the thorax, or simple contiguous surfaces, should preserve their regular and proper “The thoracic reservoir communicates with the Jungs by an infundibular orifice, situated on the external side of the embouchure of each bronchus. This orifice is dilated during inspiration, by the contraction of the two first fusciculi of the pulmonary < Cervical reservoirs (Fig. 246, 1, 1).—“They are situated above the preceding, and the inferior part of the neck and anterior part of the lung; inflated after removal from the neighbouring parts, they resemble two cones, whose rounded base looks 3, and whose pediculated summit is directe:l backwards. _ *Superiorly, these reservoirs lie against the cervical muscles; inferiorly, they corres- pond to the air-sae of the thorax, from which they are separated by tlie trachea, the the pneumogastric nerves, and the jugular veins. Inwardly, they are in j ition, and uently form a median septum which includes in its substance the two common carotid arteries. Outwardly, they are related to the origin of the cervical nerves, to each of which they furnish a small sheath, and with the vertebral artery which they surround, but do not contain in their cavity, as well as with a subeutaneous muscle and the skin. By their summits, they communicate with the anterior diaphragmatic bronchus ; and by their base they send out a prolongation which conducts the air ivto all the vertebre of the neck and back, into all the vertebral ribs, ‘ond, finally, into the spinal canal. _ In their cervical portion, these prolongations present themselves in the form of two canals extending from the base of the cervical reservoirs to the base of the cranium, where they terminate; parallel and contiguous to the vertebral arteries, like them they are | in the canals excavated in the substance of the transverse processes. From their external part arises, at the six last cervical vertebra, as many diverticuli, which, lying against each other, pass from each side in the muscles of the neck, sur- rounded by a common fibrous envelope, and apparently form a kind of canal at the inferior part of this region; when, however, this fibrous membrane is removed, it becomes easy to isolate them. and it is then seen that they are a independent, -and resemble small cornua. Highly developed in Palmipeds, they are only present in a rudimentary state in the other classes. _ “On the internal side of these conduits, we see, at the level of each vertebra, one or more orfices by which the air enters their interior; and at the intervertebral foramina another orifice, which allows it to pass into the spinal canal. From the communication established by these or:fices between the seebineiry apparatus and the spinal canal, it follows that in birds the cervical region is trave by three atmospherical currents— two lateral or intertransverse, parallel to the vertebral arteries; the third median or inter parallel to the spinal cord. _ © Just as the medullary tissue is replaced by air in the bones of birds, so might it be that the sub-arachnoidean fluid was also rep'aced by air around their spinal ' ; and observation justifies the correctness of this prevision. The dura mater, whose ty is so superior to the volume of the marrow in Mammals, exactly measures the ume of that organ in birds; so that there does not exist between the fibrous arid neryous surfaces any space for an accumulation of liquid; this anatomical fact is sufficient to demonstrate the absence of sub-arachnoidean fluid in birds. In denying the existence of this fluid, it ought to be added that in this class of vertebrata, as in the ing, the spinal prolongation is covered by a triple envelope; that in each, between mater and dura mater, is found a th'n transparent membrane, which is lubri- a serous fluid; but here this fluid does not collect, it only moistens the membrane. * Considered in their dorsal portion, the prolongations springing from the cervical reservoirs offer an entirely different arrangement to that already noticed. The inter- spinal current, having entered the thorax, terminates by passing into the first dorsal ; ; after coursing through every t of this vertebra, it eseapes by a lateral orifi-e into a small sac situated between the two first ribs, at the origin of the first dorsal nerve; from this sac, it passes into the second vertebra by an opening placed on its cep xoes- pall yobs then it flows back from this into a new air-sac developed between the second third ribs ; and passing in the same manner into the third vertebra to hl 480 vertebra. Fig. 246, See AL EEN hy Y, GENERAL VIEW OF ‘THE AIR RESERVOIRS OF THE DUCK, OPENED INFERIORLY; ALSO THEIR RELA- TIONS WITH THE PRINCIPAL VISCERA OF THE TRUNK, 1, 1, Anterior extremity of the cervical reservoirs ; 2, Thoracic reservoir; 3, Anterior diaphragmatic reservoir; 4, Posterior ditto; 5, Abdominal reser- voir.—a, Membrane forming the anterior dia- phragmatic reservoir; b, Membrane forming the posterior ditto.—6, Section of the thoraco-abdomi- nal diaphragm.—d, Subpectoral prolongation of the thoracic reservoir; e, Pericardium; f, f, Liver; g, Gizzard; h, -Intestines; m, Heart; n, n, Section of the great pectoral muscle above its insertion into the humerus; 0, Anterior clavicle; p, Posterior clavicle of the right side cut and turned outwards—From M, Sappey’s work. a THE RESPIRATORY APPARATUS. sweep through a third intercostal sac, it arrives nearer and nearer the last dorsal In their dorsal portion, the prolongations emanating from the cervieal reservoirs thus form two currents, though these are constituted alter- nately by the vertebree and the small air-sacs placed on their lateral aspect, At the same time that these sacs receive the air from the vertebrae ceding them, and transmit it to those which follow, they communicate it to all the vertebral ribs, ovat “Tn no order of birds do the serial currents leaving the cervical reser- voirs communicate with those which circulate in the cranium, Liquids injected either by the wrial portion of the vertebral canal or the lateral prolongations of the neck, never enter the bones of that cavity. Thinking that the injection might perhaps penetrate if passed in the pe direction, we have perfora the bones of the cranium, and to the aperture have adapted the extremity of a steel syringe filled with mereury; but the metal did not reach the rial prolongations of the neck. From this double experiment, we concluded that the cranial bones have no com- munication with the respiratory appa- ratus.” 3. Anterior diaphragmatic feser- voirs (Fig. 246, 3).— Placed be- tween the two diaphragms, they cor- respond : in frout, to the thoracic reservoirs, against which they stand ; behind, to the posterior diaphragm- atic reservoirs; outwardly, to the ribs and intercostal muscles; in- wardly, to the thoraco-abdominal diaphragm and cesophagus; below, to the most distant part of the tho- racic reservoir; above, to the pul- monary diaphragm, which separates them from the corresponding lung. These air-sacs communicate with the lungs by a circular opening, which originates from the great posterior diaphragmatic bronchus; there is often .a second opening of communi- cation beyond the embouchure of the trunk; this reservoir is the only one which receives air from the lung by a double orifice.” 4. Posterior diaphragmatic reser- voirs (Fig. 246, 4).—* Oval-shai like the preceding, and situated li them in the interval which separates the two diaphragms, these air-sacs are in contact, by their anterior part, with the anterior diaphragmatic re- servoirs, With which they form a ver- tical and transverse septum. Some- times this septum is carried a little more forward, and then the anterior reservoir is smaller; this is most frequent in a THE RESPIRATORY APPARATUS IN BIRDS. 481 ae Palmipeds. At other times it inclines backwards, and the anterior reservoir is larger ; tn era imap is peculiar to the Gallinacw. And, lastly, this partition divides the intercepted space between the diaphragms into two equal cavities; rapacious birds offer ; ’ examples of this. ; - “Behind, these reservoirs stand against the abdominal sacs, from which they are ‘separated by the thoraco-abdominal diaphragm; below, they respond to the sternal ribs and the lateral parts of the sternum; above, to the pulmonary diaphragm; inwards, to the thoraco-abdominal diaphragm ; outwards, to the vertebral ribs and intercostal muscles. alta. 8 opening, situated in the middle part of the external border of the lang, or # little more behind, establishes their communication with that organ, This orifice, , which is remarkable for its great dimensions, occupies the extremity of a voluminous = bronchial tube which follows the direction of the generating trunk, and in such a manner that this trunk appears to pass directly towards the posterior diaphragmatic reservoir, and to as a canal.” Dag Be inal reservoirs (Fig. 246, 5).—*“ The two air-sacs situated in the abdomen 4 t themselves, when inflated, as two enormous bladders, the capacity of each a Riffering but little from the volume of the trunk. Situated between the superior P= and lateral parictes of the abdomen on one side, and the ‘abdominal viscera on the oe they cannot be dilated without driving the intestinal mass downwards and ward 8. “Their anterior extremity, continuous with the lung, is somewhat inflected to pass under the fibrous arch extending from the spine to the pelvis. “Their posterior extremity, dilated and voluminous, responds to the cloaca. Out- wardly, they alhere by cellular tissue to the thoraco-abdominal diaphragm, the parietes of the abdomen, and those of the pelvis. Inwardly, they are in coutact with the intes- tinal mass and the testicles or ovaries. Below and in front, they rest on a fibrous septum, which in all birds divides the abdomin 1 cavity into two smaller cavities: one , Which represents the abdomen and lodges the liver, the other posterivr, which represents the pelvis and contains the stomach and intestines. ‘lhis fibrous septum is ex-’ tremely remarkable in large birds, particularly the Ostrich, in-which it has been described by Perrault as a transverse diaphragm ; it is inserted into the entirécireumference of the vie bones, and sustains the stomach as well as the intestinal tube. Below and the abdominal reservoirs lie on the intestines. Above, these sacs cover the inferior face of the kidneys, and there furnish three prolongations: 1, A suprarenal pen paola ; 2, ‘'wo femoral prolongations. ' The suprarenal prolongation leaves the principal reservoir at the postero-external part of the kidneys; from thence it passes obliquely upwards and forwards, to spread over the superior surface of the spam which it depresses when the abdominal sac is inflated. Arrived at the internal border of the kidneys, these prolongations are intro- duced between the transverse processes of the sacral vertebre, and ascend from behind forwards to the height of the two first dorsal vertebre, forming two triangular canals situated above the sacrum, in the sacral channels, and separated from one another by a series of ee ne spinous processes. The suprarenal prolongations are not present in all birds; they are particularly observed in the Gallinace and diurnal birds: In some Palmi the Swan for ere ig they are equally developed ; in the Ostrich, they are replaced by the supraspinal canals. _ The femoral prolongations are two in number—an anterior small and a posterior pel they arise from the abdominal reservoir at the cotyloid cavities, and leave the ng am, -~ in traversing the bony opening through which the crural vessels pass; after clear- the limits of these cavities, they sp around the coxo-femoral articulation, and in a cweum in the majority of birds. In diurnal birds of prey, they commu- nicate with the femoral canal by an orifice situated at the anterior part of the great trochanter. ‘These prolongations, very developed in the Ostrich, also open in it into the femorul cavity ; it is not without surprise that we see this arrangement, which is peculiar to birds remarkable for their rapidity and power of flight, also present in those to which terial locomotion has been entirely denied. The abdominal reservoirs communicate with the lung by an orifice situated beneath the fibrous arch of the diaphragm, and disposed like the rose of a watering-can.” ComMMUNICATION OF THE ReseRvorRs wiru THE Bonrs,—‘ The communications of the wc anime apparatus with the skeleton in birds are extremely numerous. We will successively examine those belonging to each reservoir, “The bones which receive air from the thoragic reservoir are ; 1, The anterior clavicle, which is perforated at its two extremities; 2, The posterior clavicles, which are also perforated a little below their scapular extremity 3, The sternum which — two I Ti Obey ar s- - NG TL gee | 482 THE RESPIRATORY APPARATUS. series of openings—the middle ones that conduct the air into the sternal ridge, and the a lateral ones, very small, six to eight in number, corresponding to the intercostal spaces; 4, The scapule, which offer one or more apertures at their anterior extremity, and recei the air for the subscapular prolongation; 5, The humerus, which obtains the air for the humeral prolongation by a fossa situated at the inferior and internal part of its articu'ar head ; 6, The sternal ribs, which allow the atmosphere to penetrate by small openings at their inferior extremities. To sum up, eight bones. without the sternal ribs, wuose number varies, receive the air which fills them from the thoracie reservoir. “ The cervical reservoirs conduct the air: 1, To all the cervical vertebra ; 2, To all the dorsal vertebra ; 8, To all the vertebral ribs. The vertebrie of the neck are wrated in their anterior part by the currents which accompany the vertebral artery, and in their posterior part by the interspinal current. The first obtain entrance to the anterior segment by one or more orifices male in the inner wall of the intertransverse canals; the median current penetrates the posterior segment by two orifices, a right and left, situated on the inner and medullary wall of that segment. The first vertebra of the back is provided with air in the same manner, by the middle and lateral currents of the neck. This air, after passing through the first vertebra, leaves by its lateral parts, to enter a small sac; from this it goes into the superior part of the second vertebra, from this by its lower portion, to be received into a lateral sac, and so on to the last dorsal vertebra. ‘These sacsalso supply the vertebral ribs with air, which enters them by very small apertures situated at their spinal extremity. “The diaphragmatic reservoirs have no bony communications. The abdominal reservoirs supply : 1, The sacrum ; 2, The coceygeal vertebrae ; 3, The iliac bones; 4, The femurs. The air traversing the sicrum, coccyx, and ileum, comes directly from the supra- renal prolongations, and that filling the femoral cavity from the femoral prolongations. In this enumerat’on of the communications between the skeleton and the iratory apparatus, we have taken as a type the most «rated skeleton: that of diurnal birds of prey, like the eagle, kite, hawk, etc.; the hones which communicat with the air-sacs are not so numerous in the other classes, In this respect, they may be ranged in three categories: 1, Those which are eriferous in all classes; 2, Those in certain classes only; 3, And those which are not so in any class. The bones always erated are the cervical and dorsal vertebre, the sternum, and we may add the humerus, though it is not so in the Ostrich. Those erated in some classes only are: the fureulum, clayicles, sea r vertebral and sternal ribs, the sacrum, coccyx, and femurs. And the bones which are never «rated are those of the fore-arm and hand, the leg and foot.” SrRvcTURE OF THE ReseRvorrs.—The walls of these cavities are essentially formed by a thin cellulo-serous membrane, strengthened in some places by an external enyelope of elastic fibrous tissue. Long, thin blood-vessels are distributed to the substance of ion walls; they do nut belong to the pulmonary, but to the general circulation, the arteries being derived from the aorta, and the veins opening directly or indirectly into the ven eava. No lymphatics have been found in the air-sacs. Mecuanism or Respiration IN Birps.—The anatomical arrangement deseribed above differs in so many respects from that existing in Mammals, that it ought to bring about important modifications in the mechanism of respiration. It does not come within our seope to write the history of these modifications; but we cannot dispense with indicating, in a summary way, their principal characters, in order to make known in a general manner the signification of the special organisation this apparatus offers in birds. We remark, in the first place, that the slight mobility of the vertebral ribs, and the adhesion of the lung to their inner face, only allows of a very slight dilatation of that viseus during inspiration, And the entrance of air into the pulmonary tissue is not due to this dilatation; it is due to the dilatation of the diaphragmatic reservoirs; the position of these effectively admits of their expansion, by the play of the inferior on the superior ribs. The air is then drawn into their cavity after traversing the ] bronchial tubes which open into them, and also after passing across a certain region of the capillary network formed by the canaliculi, where it comes into mediate contact with the blood, and is submitted to the necessary transformations. The atmosphere, — therefore, arrives in the diap|:razmatic sacs partly pure and partly altered by its contact with the blood. During expiration, it again resumes the course it followed on its introduction, traverses a second time the lung, and is thus respired once more before being expelled from the body, It is, therefore, obvious that the heematosic transforma- tions accomplished in the lung take place during the two acts of respiratiun—inspiration — and expiration. j In studying the part that the other reservoirs play in this function, M. Sappey has . ae RESPIRATORY APPARATUS IN BIRDS. mies 5 eres cet } entirely vitiated air, while the air of the middle reservoirs has only been ary to add that the functions of the air-sacs do not cease here ; . for it has rated that they exercise a very marked influence: 1, On locomotion, by — weight of the body, and, by their position, rendering equilibrium more voive, the extent and power of which they augment. sacs at the moment of the expansion which draws - clamor Sappey has also noted that these contents are always — { 44] BOOK IY, UrrmNary APPARATUS. Tus apparatus, though simple, yet plays a very important part in the animal economy, as it is charged with the duty of eliminating from the blood, along with the superfluous water and other accessory substances, the exere- mentitial azotised products resulting from the exercise of the vital functions. These products we find in the urine—the liquid secreted by the kidneys, and which is carried by the ureters into a special reservoir, the bladder, w it accumulates, and whence it is expelled from the body by the urethral canal, at periods more or less distant, according to the requirements of the animal. The kidneys, the essential organs of urinary depuration, will be first studied; then the excretory apparatus ; and, finally, a brief notice will be given of the suprarenal capsules—small appendicular bodies annexed to the kidneys, and whose function is not yet determined. Preparation.—Place the animal in the first position, and remove one of the posterior limbs. Take out the intestines, adopting ‘the precautions indicated at page 385. Saw through the pelvic symphysis, as well as the neck of the ilium on the side opposite the remaining abdominal member, removing the coxal portion between these sections. The pelvic cavity being now opened, the urinary apparatus is exposed, and to complete the pre- paration it is necessary to: 1, Remove the peritoneum, to show that the urinary appara- tus is situated external to that membrane; 2, Free the ureters anil kidneys from the cellulo-adipose tissue surrounding them, but retaining the vessels of the latter, and leaving undisturbed their relations with the pancreas and suprarenal capsules; 3, Inflate the bladder, and dissect its neck, taking care to preserve the orbicular peritoneal fold which envelops its anterior cul-de-sac. In the male, the inflation of the bladder is very simple, and requires no directions. In the female, however, it is requisite first to close the meatus urinarius, which is ac- complished by drawing its two lips towards the entrance to the vulva, by means of two chain-hooks, passing two pins through their mucous membrane, and tying a ligature behind these; the bladder is then inflated by the ureter. Independently of this dissection in situ, it is advisable to examine the urinary apparatus when isolated, and laid arranged upon a table, as in Fig. 247. We can then study: 1, By dissection, the structure of the kidneys and arrangement of the pelvis renalis; 2, The mode of termination of the ureters; 3, The interior of the bladder. 1. The Kidneys. (Figs. 182, 247.) Situation.—These are two glandular organs situated in the abdominal cavity, to the right and left of the sublumbar region, lying against the ¢ psoas muscles, and maintained in that position: 1, By an envelope grea of cellulo-adipose tissue; 2, By the peritoneum, which passes beneath them ; 8, By the pressure of the digestive organs contained in the abdominal cavity. Their situation is not absolutely alike, for the right comes forward to _ beneath the two last ribs, while the left scarcely reaches beyond the eighteenth — Z rib. The latter is therefore more posterior than the former. External conformation.—Studied externally, the kidneys present a special form, which often serves as aterm of comparison, and resembles more or less that of a haricot bean, or the heart on a ‘playing card. The latter con- figuration is most frequently noticed in the right kidney, the left being generally like the first. ~ - a2 THE KIDNEYS. 485 . Flattened on both sides, the kidneys show two perfectly smooth faces, the inferior of which always exhibits a variable number of furrows which , aa. Fig. 247. is yo ini 4 ; : | * és * .. j My iN 5 Wie pal -ee a) yi ily € A wt 5 &) A, Left kidney; B, Right kid- ney; a, b, Ureters; ©, ¢, Supra-renal ‘ capsules; , Bladder; EB, E, Testicles; e, Head of the epididymus ; e’, Tail of the epididymus ; F, Deferent canal; G, Pel- vic dilatation of the defe- rent canal; H, Left vesicula seminales; the right has been removed, along with the deferent canal of the same side, to show the in- sertion of the ureters into the bladder; 1, Prostate ; J, Cowper’s glands; Kk, Membranous, or intra-pel- vic portion of the urethral canal; L, Its bulbous por- tion; M, Cavernous body of the penis; m, m, Its roots; SS N, Head of the penis.—l, SUPERIOR AND GENERAL view or tHE Genrro- Abdominal aorta; 2, 2, Ar- URINARY APPARATUS IN THE MALE, with Tux ‘téries (renal) giving off the ARTERIES. principal capsular artery ; 3, Spermatic artery; 4, Common origin of the umbilical and arteries of the bulb; 5, Umbilical artery 6, Its vesical branch ; 7, Internal artery of the bulb; 8, Its vesico-prostatic branch, 486 THE URINARY APPARATUS. lodge the arteries; the right kidney has always a special furrow for the ureter. Each kidney has a circumference divisible into three borders, only the internal of which offers a certain interest. This is deeply notched, to form the fissure or hilus of the kidney, which lodges the vessels and nerves of the organ, as well as the origin of its excretory canal. Weight.—The kidneys vary much in weight in individuals. The right is always more voluminous and heavy than the left, its average weight being 27 ounces, while that of the last is 25 ounces. Relations.—The relations of these two glands with the neighbouring parts ought to be particularly examined. The right kidney corresponds, by its upper face, to the great psoas muscle, the muscular portion of the diaphragm, and to the last, or even the second-last rib. Its inferior face, incompletely covered by peritoneum, adheres, for the greater part of its extent, either to the pancreas and supra-renal capsule, or to the base of the cecum, by means of a loose and abundant cellular tissue. The internal border is in contact with the posterior vena cava and the small muscle; the anterior, with the base of the right lobe of the liver and the lobule of Spigel (lobus Spigelii), through the medium of the peritoneum ; — the posterior border is enveloped in peritoneum. The left kidney affects, by its superior face, the same connections as the right, except in its relation with the second last rib. Its inferior face is almost entirely covered by peritoneum, and responds, in front and inwardly, to the supra-renal capsule. The internal border is margined by the aorta; the anterior touches the base of the spleen and the left extremity of the pancreas; the posterior is, like the inferior face, in contact with the serous membrane of the abdominal cavity. Internal conformation.—If a horizontal section is made of the kidney, it will be found to possess a cavity called the renal pelvis, into which the urine secreted by the gland flows, and at which the ureter commences. Placed in the middle of the kidney, near the hilus, the pelvis is elongated from before to behind, and depressed from above to below. Within it is remarked a wide infundibulum, the origin of the ureter (the sinus-renalis). Opposite to this funnel-shaped space is a very prominent crest that runs along the whole length of the external side of the pelvis, and on which are noticed the orifices of the uriniferous tubes ; these, by pressing the tissue of the kidney with the fingers, can be made to pour out the urine accumulated in them. The renal cavity forms some very small diverticuli opposite the infundibulum, the largest of which, situated before and behind the latter, are named the arms of the pelvis, This cavity is lined by a transversely plicated mucous membrane, continuous with that of the ureter, and is covered with the epithelium of the uriniferous tubes which open on the border of the crest. Srrvorure.—The kidneys present for study in their structure: 1, An enveloping tunic ; 2, Their proper-tissue ; 3, A cavity named the renal pelvis, into which the urine secreted in the glandular tissue flows, and which serves as the origin of the ureter. 1. Exvetorine Tun1o.—This is a» fibrous membrane, intimately united to the proper substance of the kidney, into which it sends a multitude of prolongations, and is folded around the blood-vessels in such a manner as to form sheaths, which enter with them into the organ. (Some authors— among them Leyh—describe, in addition to this capsula propria, a thin layer formed by the condensed areolar matrix of the kidney, from which it can be easily torn.) THE KIDNEYs. 487 Prorer Tissuzr.—The glandular tissue of the kidneys (areola parenchyma or matrix) has, externally, a reddish-brown colour, more or less deep in different individuals. It is dense and friable, and easily torn when deprived of its fibrous capsule. Its substance is not everywhere homogeneous: very dark-coloured externally, where it forms the cortical layer, it becomes whiter around the pelvis, where it consitutes the medullary layer ; where the latter comes in contact with the former, and sometimes even near the pelvis, it assumes a tint like that of wine. These two portions are not well defined, but penetrate each other reciprocally, so as to compose, at their point of junction, irregular festoons, very readily perceived in a horizontal section of the kidney (Fig. 248). The cortical is also distinguished from the medullary substance by its granular aspect, and the presence of minute, reddish spheres, readily visible to the naked eye, and named Malpighian corpuscles ; while the medullary substance appears composed of radiating fibres. Fig. 248. HORIZONTAL LONGITUDINAL SECTION OF THE HORSE’S KIDNEY. a, Cortical (or vascular) portion; +, Medullary (or tubular) portion; c, Peripheral rtion of the latter; d, Interior of the pelvis; a’, d’, Arms of the pelvis; e¢, rder of the crest; /, Infundibulum; g, Ureter. In the Horse, the tissue of the kidney cannot be divided into lobules or “apo to the naked eye it appears to be composed of fibres that start every part of its exterior, and converge towards the crest of the pelvis. A microscopical examination demonstrates these fibres to be canals or tubes ; hence they are designated tubuli uriniferi or Bellini’s tubes. A delicate connective tissue, a kind of stroma, which is very rare in the cortical, but more abundant in the medullary substance, especially in the vicinity of the pelvis, sustains the vessels and nerves, and unites the tubuli uriniferi to each er. The tubuli uriniferi are constituted by a proper amorphous membrane, very thin and elastic, whose internal face is lined by simple epithelium that readily alters; the cells are polygonal in certain points, polyhedral in others, and transparent or granular. 488 The uriniferous tube has not everywhere the same direction or diameter — Taking it at its termination on the crest of the pelvis, and following it to its = : io Fig. 249. ~, am SECTION OF THE CORTICAL SUBSTANCE OF THE KIDNEY, A, A, Tubuli uriniferi divided transversely, showing the spheroidal epithelium in their interior; B, Malpighian capsule; a, Its afferent branch of the renal artery ; b, Its glomerulus of capillaries; c, c, Secreting plexus formed by its efferent vessels; d, d, Fibrous stroma, DIAGRAM OF THE COURSE OF THE URINIFEROUS TUBULE, a, Orifice of tubule at pelvic crest ; 6, Recurrent branches which form loops, ¢, in the medullary portion of the kidney, and terminate in the Malpighian capsules in the cortical portion, THE URINARY APPARATUS, tz ——". origin in the Malpighian body, it is found that the tubule is at first single, straight, and voluminous, but that during its course across the medullary substance it divides into three or four tubes, which,in their turn, subdivide in a dicho- These divisions — are less voluminous and straight, — and their diameter is uniform until — they ‘reach the cortical substance; — here they bifurcate, each branch — tomous manner. becomes flexuous, and is designated = the uniting tube, and is continued = in a kind of elongated U shape, the a ansiform tube of Henle, which des- > cends towards the centre of the kidney, The ascending branch of this ansiform tube, whose diameter 3 is very small, suddenly dilates on — entering the cortical substance, "2 describes several bends, contracts = into a narrow neck, and then opens . into a Malpighian body, after having taken the name of Sasa en tube. The corpora Malpighiana (or — capsules) are minute vesicles, vige walls possess the same structure as the uriniferous tubes; each lodges a cluster of arterial capillaries or renal glomerulus, and has two oppo- site openings: one communicating = a a * a THE KIDNEYS. between the corpora and convoluted tubes, the ot to the afferent and efferent vessels of the glomerule, 3. Vessets anp Nerves.—a. The kidney pos- sesses a special artery and vein, remarkable for their enormous volume. The artery forms several branches which reach the kidney by its inner border and inferior face, and divide into a certain number of principal vessels, which are disposed in a wavy manner on the limits of the cortical and medullary substances. From them are given off branches to each of these substances, and among those distributed to the cortical are some regularly disposed, which furnish, on each side, the glomerule ramifications ; these are the afferent vessels or Malpighian glome- rules (or tufts); the others form a polyhedral ee around the convoluted tubes and corpora pighiana. The afferent vessels of the renal glomerules enter this plexus. The arterial branches of the medullary sub- stance descend parallel to the straight tubes, and anastomose by transverse branches, so as to form a network with elongated meshes. The vein issues from the kidney by the hilus, and succeeds the arterial capillaries. In the me- dullary substance, there are straight veins as there are straight arteries, On the surface of the organ, beneath the fibrous envelope, are the stars of Verheyen: the junction of five or six venules wh central vein. The veinlets of the two substances collect into more voluminous vessels, which form complete arches at their limits ; it is to the presence of these canals, that the dark colour observed at this point of © the renal tissue must be attri- | buted. b. The lymphatics are abund- ant at the superficies and in the mass of the organ, forming plex- uses, whose ultimate branches pass to the sublumbar glands. ce. The nerves emanate from, the solar plexus, and compose a particular network around the arteries, exhibiting, on their : : aa; course, some microscopic gan- 1, Inferior border; 2, 489 her affording a passage Fig. 251. DISTRIBUTION OF THE RENAL VESSELS IN THE HORSE’S KIDNEY. a, Branch of renal artery ; aj, Afferent vessel ; m, m, Mal- pighian tufts; ef, ef, Ef- ferent vessels ; p, Vascular plexus surrounding the tubes; st, Straight tube ; ct, Convoluted tube. ich converge towards a TRANSVERSE SECTION OF THE KIDNEY. Cortical tissue; 3, Section of blood-vessels ; 4, Pelvis; 5, Ureter; 6, Superior glia. It is not known how they border; 7, Renal artery; 8, Proper capsule, terminate. ___Devetorment.—The kidneys appear very early in the foetus, above and a little behind the Wolffian bodies. They are then very distinctly lobulated, but the lobes gradually become fused, and have entirely disappeared at birth ; the 490 THE URINARY APPARATUS, small irregularities on the surface being the only indications of their having existed in Solipeds. Funotions.—The kidneys are the organs which secrete the urine; but this secretion does not take place to the same extent in all parts of their tissue. The abundance of vessels in the cortical substance, the presence of the Malpighian corpuscles, and the flexuosities described by the uriniferous tubes, sufficiently indicate that this substance should be the principal, if not the exclusive, seat of the secretory function. But in what manner does this secretion take place? At present it is generally agreed that the urinary secretion is simply an infiltration of the elements of the urine contained in the blood, through the walls of the vessels and the uriniferous tubes. A knowledge of the phenomenon of dialysis, discovered by Graham ; and the difference existing between the diameter of the afferent and efferent vessels of the Malpighian glomerules—a fact whose importance was pointed out by Ludwig—sufficiently explains this filtration of the urine through the tissue of the kidneys. . - 2. The Ureters. (Fig. 247.). Form.—The ureter is a membranous canal, having the diameter of a thick — goose quill, which conveys the urine from the pelvis of the kidney into the bladder. Its origin, course, termination, and structure, will be successively considered. Origin.—It has been already shown that the origin of the ureter js at the infundibulum of the pelvis; it leaves the kidney by the internal fissure or hilus, curves outwards, passes along its lower face, and is inflected backwards in quitting the organ. Direction —The course it afterwards follows is almost in a straight line towards the pelvic cavity, along with the aorta or posterior vena caya, according to the side to which it belongs; it is in contact with the small psoas muscles, and proceeds above the peritoneum. After passing beyond the terminal branches of the aorta, which it crosses very obliquely, it becomes enveloped in a short peritoneal fold that maintains it against the lateral wall of the pelvis; it afterwards emerges from this fold, and reaches the posterior and superior part of the bladder. Termination Having reached that viscus, its termination takes place as follows: instead of opening directly into the bladder by traversing at once, and perpendicularly, the two membranes composing the organ, the ureter at first pierces the muscular coat, between which and the mucous membrane it passes for about an inch, and then opens on the surface of the latter. This arrangement prevents the flowing back of the urine into the ureter during its expulsion, the intermembranous portion of that canal being strongly compressed by the external pressure then exerted by the muscular coat, and by the internal resistance which the accumulation of urine in the bladder opposes to this pressure. So well are Nature’s intentions fulfilled in this respect, that we may inflate the bladder by the ureter, after tying the canal of the urethra, and press vigorously on the distended organ, without being able to make a single bubble of air pass through the perfectly pervious canal, Srrucrure.—The excretory canal of the kidney is composed of three tunics: 1. An internal mucous tunic, continuous, in front, with that lining the pelvis of the kidney, and behind, with that of the bladder. It is very thin, pale, ridged longitudinally, and has a stratified tesselated epithelium, (It has some mucous follicles, but no villi.) THE BLADDER. 491 2. A middle muscular layer arranged in two orders: a superficial, whose fibres are circular, and a deep, passing in a longitudinal direction. (Leyh and other authorities describe the arrangement of the muscular planes, which are composed of smooth fibres, to be the reverse of this, the longi- tudinal being superficial, and the deep circular.) F 8. An external tunic, composed of connective tissue and elastic fibres. The muscular tissue of the ureter, by contracting, accelerates the flow of the urine. 3. The Bladder. (Fig. 247.) Position.—This is a membranous reservoir, lodged in the pelvic cavity, where it occupies more or less space, according to the quantity of urine it contains; it may extend beyond the pubis, into the abdominal cavity. Form.—Considered in a moderate state of plenitude, the bladder is ovoid in figure ; its large extremity being turned forward, forms a rounded cul-de- sac (fundus), at the bottom of which is remarked a kind of cicatrice, caused by the obliteration of the urachus. The other extremity terminates, posteriorly, by a well-marked constriction, the neck of the bladder, which gives rise to the urethral canal. Weight.—The average weight of the empty bladder is about sixteen ounces. Relations and mode of attachment.—The bladder responds: above, to the vesicule seminales, to the pelvic dilatations of the deferent ducts, as well as to the rectum ; below, to the inferior wall of the pelvis, on which it rests (by its base); on the sides, to the lateral walls of that cavity. In the female, the superior face of the bladder is in relation with the uterus and vagina, which entirely separate it from the rectum. The posterior extremity or neck (cervix), flanked on each side by the lobes of the prostate, is fixed below to the ischio-pubic symphysis, by means of a particular ligament or fasciculus of elastic and contractile fibres, which are detached from the muscular layer, and expanded over the lower face of Wilson’s muscle, to be carried backwards and downwards, and terminate on the surface of the internal obturator muscle. The anterior extremity, or fundus, usually responds to the pelvic curvature of the large colon. It is remarked that this extremity is covered by a serous cap, which is prolonged backwards on its body, but further above than below. This covering is continuous with the parietal layer of peritoneum, and adheres closely to the muscular tunic of the bladder, so that it constitutes its chief attachment ; its disposition is precisely similar, in principle, to that of the other serous visceral membranes. Thus the peritoneum, after covering the walls of the pelvis, is reflected on the organs contained in that cavity, and in particular on the bladder, around which it forms an orbicular fold. This again gives rise to three secondary folds, a kind of serous layers, which are usually termed the ligaments of the bladder. One of these layers is single and vertical, and is fixed to the inferior part of the fundus; it is not rare to see it prolonged forward on the lower wall of the abdomen, as far as the umbilicus ; on its free border it is said to have a thin hem or cord, the last vestige of the urachus. If this cord exists, which appears doubtful to us, it cannot the signification given to it; for the urachus has not, like the umbilical arteries, an abdominal portion; it only commences at the umbilicus to be prolonged in the cord to the allantois. The other two serous layers (umbilical ligaments), pairs and horizontal, are attached to the sides of the 492 THE URINARY APPARATUS. fundus, and present, on their free border, a thick cord, the obliterated %, umbilical artery. . oe Owing to this ae teases of the peritoneum, the bladder is divided into Wintenenne™ ee Se | CAMOKE heb, THE KIDNEYS AND BLADDER IN THE FQ2TUS OF SOLIPEDS, A, Supra-renal capsules; B, Kidney; 6, Ureter; ©, Bladder; p, Urachus,—1, Abdominal aorta; 2, External iliac artery ; ; 3, Umbilical artery; 4, Umbilical ‘ vein. region. This tissue, constantly mixed with adipose masses around the neck = of the bladder, submits, with the serous membrane of the anterior region, to the changes in form and continual displacements of the urinary sac. ~—— THE URETHRA. 493 Interior.—This pouch, studied internally, exhibits folds and ridges more or less marked, according to its state of plenitude. It also shows, pos- teriorly, the opening of the neck, which communicates with the urethral canal, and a little higher, the orifices of the ureters. These three apertures cireumscribe a triangular space, the trigonum vesice. Srrvucrure.—The structure of the bladder is very simple. Two mem- branes compose its walls, the internal of which is mucous, and the external muscular. Anteriorly, the latter is covered by the serous investment described above. The mucous membrane is pale and thin, and is continuous with that lining the ureters and the urethra. It shows some papille and some simple tubular glands towards the neck. Its epithelium is stratified and tesselated, the superficial cells being very irregular. The muscular layer is composed of white fibres, the arrangement of which is very complicated. Certain authorities describe three superposed planes, whose fibres pass in different directions. In the Horse, the walls of whose bladder are very thin, these planes are difficult to demonstrate. The fibres are longitudinal, circular, oblique, spiral, and even twisted towards the fundus of the bladder ; the deep fibres are reticulated. In the posterior region they do not form a sphincter around the neck of the organ, as is generally believed; the real sphincter is Wilson’s muscle, which encircles thet membranous portion of the urethral ¢anal. Vessels and nerves.—The parietes of the bladder receive their blood from several sources. The principal arteries come from the vesico-prostatic branch of the internal pudic ; the umbilical artery also furnishes ramifications that reach the fundus of the organ. The lymphatics pass to the sublumbar glands. The nerves are furnished by the pelvic or hypogastric plexus, and the inferior branches of the two last sacral pairs; their twigs are spread more especially between the muscular and mucous layers. Drvetorment.—The study of the development of the urinary reservoir is very interesting. It is narrower and more elongated in the foetus than the adult, and is relatively more capacious during the whole period of intra- uterine life. It then occupies the abdominal cavity as far as the umbilical opening, and is flanked by the two umbilical arteries. Its posterior extremity alone enters the pelvis ; the anterior extremity, forming a veritable neck, is continuous with the urachus, just as the neck, properly so called, is continuous with the urethral canal (Fig. 253). At birth, this anterior neck separates from the urachus, and is transformed into a free cul-de-sac ; while the bladder is gradually withdrawn into the pelvic cavity, carrying with it the umbilical arteries, and finishes by acquiring the position it definitiyely preserves in the adult. Founctions.—The part played by the bladder is one of incontestible utility. In permitting the accumulation of the urine and the intermittent expulsion of that excrementitial fluid, it spares animals the disagreeable condition in which they would be placed if the liquid secreted by the kidneys was continually being discharged as it was produced, 4. Urethra. The description of this organ will be given with that of the genital organs ; asin the male it is common to the urinary and generative apparatus ; even in the female it is intimately connected with the latter. : ’ 494 THE URINARY APPARATUS. 5. The Supra-renal Capsules. (Fig. 247.) Situation—Form.—The supra-renal capsules (or adrenals) are two small bodies applied to the lower face of the kidneys, in front of the hilus, and close to their inner border. They are elongated from before to behind, flattened on both sides, and irregularly lobulated on their surface. ‘Their length is from 2 to 24 inches, and width from 1} to 14 inches. They have not the same volume, the right being larger than the left. Relations.—A large amount of connective tissue, vessels, and nervous filaments attach these bodies to the neighbouring organs. The right is related, in front, to the liver; above, to the right kidney; and inwardly, to the posterior vena cava and the ramifications of the solar plexus. The left does not touch the liver or spleen, but, by its inner border, is applied against the posterior aorta and great mesenteric artery. Srructurr.—At present, anatomists are not agreed as to the structure of the supra-renal capsules. ‘The following is what is probably most reliable in this difficult point in normal histology. These organs offer an enveloping membrane arid parenchyma. The enveloping membrane is fibrous, and sends off, from its inner face, prolongations which pass into the parenchyma and form cylindrical spaces, subdivided by transverse lamella. These spaces are named glandular cavities ; but the septa soon become thin, and disappear almost completely, leaving nothing but some very few trabecule of connective tissue. The parenchyma is divisible into two layers: the cortical and medullary substance. The first is of a dark-brown colour; the second is yellow and soft, and does not show any cavity in its centre; that which has been described is the result of the destruction of its proper elements, which soon change after death. The glandular cavities of the cortical substance are filled with nucleated, granular, and often fat cells in the adult animal; near the central substance these cavities only contain a single cell. The medullary substance has, for its basis, a very delicate reticulum, supporting cells analogous to those of the cortical substance, and stellate elements which Luschka considered were nerve cells. Vessels and nerves.—Like the kidneys, which are contiguous to them, the supra-renal capsules receive a large quantity of blood, compared with their small volume. The arteries are branches of the neighbouring vessels: the mesenteric and renal. They form avery delicate plexus in the parenchyma. (They keep to the stroma of the trabecule; consequently, their finest ramifications are found in the secondary septa of the cortical substance, where they form elongated plexuses, which are rounder in the medullary portion. In the middle of the latter, the venous ramuscules unite, and give rise to a considerable trunk, the vena supra-renalis, on which the organ is placed as on a pedicle. It is this vein which constitutes the debated cavity. ih veins are satellites of the arteries in the tissue of the organ, and pass into the renal vein or posterior vena cava. The lymphatics are scarce. The supra-renal bodies receive many ganglionic nerves derived from the solar plexus, and whose mode of termination is unknown. (As mentioned by Chauveau, the nerves of these organs are extremely numerous, they being more abundantly supplied than any other structure of the kind in the body ; a large number of small branches enter the cortical portion, to become ~~ ‘ \ . S ’ THE URINARY APPARATUS. 495 developed in the medullary tissue. As these nerves do not leave the medullary substance, and as, besides, its cellular elements appear to be of the same nature as the multipolar ganglionic cells, it is presumed that the nervous fibres emerge from these globules, and that the medulla acts as a ganglionic nervous centre. Though Leydig fully believed the internal portion to be of a nervous character, he thought another function might be attributed to the cortical, in consequence of its being most frequently of a fatty nature. was the first, in 1839, to class these organs with the nervous and Remak, in 1847, by his researches in embryology, was led to them with the sympathetic ganglia, and named them nervous glands. jury to the dorsal portion of the spinal cord causes congestion and hypertrophy of the supra-renal capsules. In a watery solution of the cortical portion, a rose-tinted substance has been discovered, which changes to green with persalts of iron.) .—These bodies are relatively larger in the foetus than the adult, though this difference does not influence their structure. Funcrions.—Their uses are still unknown; they are ranked in the eategory of blood-vascular glands, along with the spleen and thyroid body, whose functions are also not yet ascertained. (Leydig is of opinion that these bodies should be regarded as belonging to the nervous system.) DIFFERENTIAL CHARACTERS IN THE URINARY APPARATUS OF OTHER THAN SOLIPED ANIMALS, 1. Kidneys—In other than Soliped animals, the renal glands are simple or multiple, or in other words, simple or lobulated. In the Oz, the kidneys have an elongated sha from before to behind, which is altogether characteristic; and, in addition, they preserve during life the lobulated form only seen in the other animals during intra- uterine existence. Each agglomeration is composed of from fifteen to twenty secondary kidneys; but the pelvis is not formed in the centre of this agglomeration, being carried altogether outw and occupying an excavation in the inferior face of the organ, which ts the hilus. This cavity is divided into as many short, wide prolongations—the as there are principal lobules; the uriniferous tubes from each lobule open on a small papilla, which projects into the bottom of the calyx. This papilla is, therefore, nothing more than the crest of the simple pelvis in the kidney of Solipeds (Fig. 256). In the Sheep, the kidneys are not lobulated, and the pelvis is carried to the inner border, as in the Horse. The cage i of the Pig are simple and voluminous, and their pelvis is disposed as in the Horse. (There are 10 or 12 papillw, and as many calices.) In the and Cat, there are no calices absolutely comparable with those of Ruminants. The pelvis is simple, and presents at the bottom a single, large, elongated tubercle, that has at its base some very short projections or pillars. 2. Bladder —The most important difference in the bladder of the domesticated animals consists in the extent of the development of its peritmeal envelope. In non- omg animals this covers all the organ to the neck; the ligaments are also very short, and the viscus may be easily projected into the abdominal cavity. The bladder is thin, and of a considerable capacity in Ruminants and the Pig; in the Dog, on the contrary, it has a very thick muscular layer, its fibres forming distinct fasciculi, especially when in a state of retraction. (In Ruminants, the orifices of the ureters are near each other; at the fundus the mucous membrane shows a small fossa which is continued by a narrow canal that terminates in a cul-de-sac, and constitutes a free appendix about f an inch long, and of the thickness of a goose-quill.) 8. Supra-renal capsules —These small organs are discoid in the and Pig, reniform in the Dog. In the Oz, they are situated at a certain distance in front of the kidneys, and their shape is like that of these bodies in the Horse; though they are a little constricted in the middle, and slightly curved. In Birds, the kidneys “are lodged at the same height, behind the peritoneum, imme liately posterior to the lungs, and in the lumbar and pelvic regions, where they occupy several foss@ excavated in the upper face of the pelvis. Their form is irregular and more or less elongated, depending upon the bones and other parts to which they are 496 THE URINARY APPARATUS. applied, and on which they are moulded. In many birds, nevertheless, three portions, more or less separated by fissures, may be recognised. The ileo-lumbar portion (sonamed = because of its constant position in this region) is the most advanced; it is often the largest. The middle is the narrowest; it is turned towards the ileo-sacral region, to enter the pelvis. The posterior is contained in that cavity, and is again larger. These two latter portions are designated as the anterior or superior pelvic, and the inferior or deep pelvic portions, Their internal and superior border is often notched by a series of trams- Fig: 254. Fig, 255. Fig. 256. a | KIDNEYS OF THE OX, Fig. 254.—Right kidney, viewed on its upper and external face. Fig. 255.—Left kidney, from its internal and inferior face; a, Pelvis; 6, 6, 6, Branches of the pelvis terminating in calices; c, Ureter; d, Renal artery. Fig. 256.—The calices in the left kidney: The contents of the hilus, including the branches of the pelvis, have been removed to show the tubercles at the bottom of these calices. Only seven are visible, the others being beneath the borders of the renal fissure. verse fissures produced by the protrusion of the transverse processes of the sacral yerte- bre, as the lungs are furrowed by the projection of the ribs.”" The excretory apparatus is incomplete, and is only formed by the ureters, which open into the cloaca, where the urine is mixed with the feces. Only one bird, the Ostrich, possesses a bladder, which is disposed in a particular manner. COMPARISON OF THE URINARY APPARATUS OF MAN WITH THAT OF ANIMALS, 1. Kidneys.—The two kidneys of Man have, like those of the smaller domestiested animals, the same shape—that of a haricot bean. The average weight is about from three to five ounces. Contrary to what is observed in the Horse, the left kidney is more voluminous than the right, and is higher. ona an sol HE The kidneys are simple externally, though their tissue is disposed in distinct lobes, which number from eight to fifteen, and are composed of a Malpighian pyramid and a ' Cuvier, ‘Anatomie Comparée, 2nd edition, Paris, 1836-46. te ol pam ty el al se re 5 4 ese ) ‘THE E URINARY APPARATUS. 497 nid Melanie they terminate, towards the hil renal og d by a calyx, and are separated by small ig na hy the » canals are disposed erg tne Eeanty are Sens tee te oes Pa os which cavity or great ca t opens ial Thiet immediately f follo owed by the ureter. . ler —The large Teche, Ay Agee! pl ig ree baring acs here it is continuous with th canal ; its summit is directed upwards, ; ea Its ao of roger te) and internal peepee are the solialé and, as in orse, neum envelops it very incompletely, Met ce aipsused inte lee place: a superficial, which furms a band ; 1 from the anterior to the posterior face in g over the summit; a ne whose fibres aro cireular; and a deep plano with retioulated fibre. Supra-r —This name is quite appropri ese es, as in Man, or vast i hat foton, thoy forms a Lindof hsknee’ that covers tho uppér part of of the » is nothing to add respecting their structure, — ‘Se SS > 2s : eet Ae ee Or ee a ~~ an -- at their origin as in the Ox; ipa Panag no Sm (= f 498. ] BOOK VY. CIncULATORY APPARATUS. Tue animal economy is incessantly traversed by two fluids—blood and lymph. The blood is a liquid, coloured bright-red or brown by particular globules, from which the tissues derive not only the materials for nutrition and secretion, but also the exciting principle which vivifies the organic matter. It is named red or dark-coloured blood, according to its tint. The lymph or white blood is a transparent, citrine-coloured fluid, which can be obtained from the majority of the organs. That which comes from the abdominal portion of the alimentary canal is charged, during digestion, with a portion of the reparative materials elaborated in that apparatus, and is distinguished by its lactescent aspect; it is designated the chyle. Fig. 257. THEORETICAL PLAN Of THE CIRCULATORY SYSTEM. (H, D, C, E, The canal for red blood; ©, B, A, G, Canal for black blood. The arrows indicate the course of the blood. The-two canals are represented in their middle portion, AB, CD, as isolated; but in nature they are enveloped at this point in a common sac that concurs to form the heart.) 4 These fluids are garried by vessels—tubes which are continuous with one another. When joined together, end to end, these tubes give rise to three principal canals : “One of these canals extends from the lungs to all parts of the body, and is traversed by red blood, ——— —_ THE HEART. : 499 ' ©The second extends from all parts of the body to the lungs, and carries dark blood. “The third passes from the majority of the organs towards the canal carrying dark blood, in which it terminates; it conveys the white blood or ph. “ The red-blood and dark-blood canals bear the greatest analogy to each other. Both are simple in their middle portion, which alternately dilates and contracts to impress upon the blood the movement necessary to life. Both present at their extremities innumerable ramifications, which ultimately _ each other; so that the fluid they carry passes from one to the other a constant and circular direction. Both are composed, at their origin, of vessels in which the blood moves in confluent columns: these are the veins ; and in their terminal’ part, of vessels in which the same liquid is spread in divergent columns: these are the arteries. “The canal for white blood is composed of a single order of vessels, the ics : converging tubes, whose common trunk opens into the circulatory canal that results from the abouchement of the red and dark blood canals; the relation it affects with these latter is that of a tangent with its cir- eumference.”—Sappey. These three canals constitute the circulatory apparatus. This apparatus therefore comprises: 1, The heart, a central organ, — oe to propel the blood ; 2, A system of centrifugal vessels, the arteries, which carry the blood from the heart into the different organs; 3, A system of centripetal vessels, the veins, which bring the nutritive fluid to the heart; 4, The /ymphatics, an accessory centripetal system, destined to conyey the lymph into the blood-vascular circle. Tn many anatomical works, the study of this apparatus—the heart, arteries, veins, and Jymphatics, is designated “ angiology.” FIRST SECTION. Tue Heart. Tue history of the heart comprises: 1, A general view of the organ; 2, The study of its external conformation ; 3, Its interior ; 4, Its structure ; 5. A description of the pericardium, the serous cavity containing it; 6, A glance at its physiology. 1. The Heart as a Whole. (Figs. 230, 234, 258, 259.) General sketch—The heart, the central portion of the circulatory apparatus, is a hollow muscle, whose cavity is divided by a thick vertical septum into two perfectly independent pouches. Of these two contractile one placed on the track of the dark blood, propels it into the lungs ; the other, situated on the course of the red blood, distributes it to all parts of the body. Each of these is subdivided into two superposed compartments by a cireular constriction, at which is a membranous valve that at certain fixed iods is elevated, and then forms a complete horizontal partition extended Sieweus the two compartments, The superior compartment receives the convergent or content K 500 THE CIRCULATORY APPARATUS, gives origin to the divergent or centrifugal part of the same canal,andis designated the ventricle. The cavities of the heart are distinguished into right or anterior, amd left or posterior, because of their relative positions. There are, then: & right auricle and ventricle, the two dark-blood pouches; and a left auricle and ventricle, situated on the track of the red-blood canal. TA Situation.—The heart, enclosed as it is in a fibro-serous sac, named the — pericardium, is placed in the chest between the two layers of the mediastinum, opposite the third, fourth, fifth, and sixth ribs; in front of the diaphragm, which separates it from the abdominal viscera; above the sternum, which appears to support it; and beneath the vertebral column, to which it is suspended by means of the large vessels. (Between the middle of the anterior border of the heart, in front, and the entrance to the chest, is an interval of about four inches ; and behind, at the same level, this organ is at a similar distance from the diaphragm. It is distant from the fifth and sixth dorsal vertebre, from which it is suspended, about 44 to 5 inches in an average-sized Horse.) os Form and direction.—The heart presents the form of an inverted cone, slightly depressed on each side, and whose axis, directed obliquely downwards and backwards, deviates a little to the right at its superior extremity. Volume.—In a middle-sized Horse, the greater axis of the heart is about 10} inches in length; its antero-posterior diameter, measured near the base, is equivalent to about 74 inches. Its lateral diameter does not exceed from 5 to 54 inches. Capacity.—It is very difficult, if not impossible, to obtain the exact capacity of the heart’s cavities. From reasoning, one is led to think that the two hearts have exactly the same capacity, and that this capacity is equivalent to an average of 1 to 1} pints. The amount obtained by measurement is much more considerable; but then the heart is distended to a greater degree than in its physiological state. Weight.—The weight of the heart varies with the size of animals, and that to a considerable degree. Its average is about 67 pounds. (The volume and weight of the heart are very much greater in well-bred than in under- bred Horses. Its dimensions and capacity are greater in the living than the dead animal; as, after death, its cavities contract, particularly the aortic ventricle, whose walls are the thickest. This ventricle will then scarcely contain more than 3—-4ths to 1}th gills; the pulmonary ventricle, which is not so thick, and consequently less contracted, may usually receive double that quantity; while in animals experimented on when expiring, it was observed that these two ventricles were much more capacious, and that each contained at least from 1} to 14 pints.) External Conformation of the Heart. (Figs. 258, 259.) The cone represented by the heart is divided by.a horizontal groove into two unequal portions: the one superior, comprising the auricles or auricular mass ; the other inferior or principal, formed by the ventricles or ventricular MA88, ~ A. Ventricttar Mass.—It is this which determines the conical shape of the heart, and constitues its largest portion. Owing to the slight flatten- ing which depresses the organ in a lateral sense, it may be considered as 4 THE HEART. 501 :: having a right and left face, an anterior and posterior border, an apex, and a base. ’ The right face, smooth and rounded, is traversed by a vascular furrow parallel to the axis of the heart, and which divides this face into two sections: an anterior, belonging to the right ventricle ; and a posterior, less extensive, forming part of the left ventricle (Fig. 259). The left face, disposed in the same manner, also shows a groove on the limit of the two ventricles, whose direction slightly crosses the great Fig. 258. THE HEART AND PRINCIPAL VESSELS; LEFT FACE, a, Right ventricle; , Left ventricle; c, Right auricle; d, Left auricle; ¢, Pul- monary artery; e’, Obliterated arterial canal; f, Pulmonary veins; g, Anterior aorta; A, Left axillary artery; i, Right axillary artery, or brachio-cephalic trunk ; j, Origin of the dorsal artery; 4, Origin of the superior cervical artery ; t, Origin of the vertebral artery ; m, Origin of the inferior cervical artery; n, Origin of the internal thoracic artery ; 0, Origin of the external ditto; p, Carotid arteries; g, Posterior aorta; r, Anterior vena cava; s, Trunk of the axillary vein; ¢, Trunk of the internal thoracic vein; u, Trunk of the dorso-cervical vein; v, Posterior vena cava; v', Embouchure of the hepatic and diaphragmatic veins; z, Vena azygos; y, Thoracic duct; z, Embouchure of that vessel, placed near the origin of the anterior vena cava—1, Right cardiac artery; 2, Left cardiac artery; 3, Auriculo-ventricular brancb- of the latter; 4, Its ventricular branch ; 5, Cardiac vein. diameter of the heart from behind to before, and above to below, and which is much nearer the anterior than the posterior border (Fig. 258). 502 THE CIRCULATORY APPARATUS. These two faces respond, through the medium of the pericardium, to the plure and the pulmonary lobes ; the latter separate them from the thorax, ex- cept towards the middle and apex of the organ, where these faces come directly in contact with the thoracic parietes through the notch at the inferior border of the lung, and which we know is more marked in the left than the right. The borders are thick, smooth, and rounded. The anterior, formed by the right ventricle, is very Fig. 259. and before to behind ; it then inclines on the sternum more or less, according to the sub- jects. The posterior border, much shorter than the perce: nearly vertical. Superiorly, it is separated from the dia- mi phragm by the lung; but, - below, it is quite close to - that muscular septum. The apex, or point of the ventricular cone, is blunt, slightly rounded, turned to the left, and formed entirely by the left ventricle. The base responds on the right, in front, and behind, to the auricular mass ; it gives exit on the left, and a little in front, to the two arterial aortic and pulmonary trunks, B. Avricorar Mass.— Elongated from before to be- hind, disposed like a crescent above the right side of the base of the ventricles, con- stricted in its middle part, on the limit of the two auri- THE HEART AND PRINCIPAL VESSELS; RIGHT FACE, cles, the auricular mass pre- a, Right ventricle; b, Left ventricle; c, Right auricle; sents for study three faces, vena cove; gy gh'Bulspotary veingy Bk’ Divisions nto een eee See SASS Oy Be eee ees LR sgbescder yh The superior face is di- the pulmonary artery; 7, Posterior aorta; 7, An- seioe wart 5 id Thoracte "duct ; 1, Right catdiei vided by a middle constric- artery ; m, Its vertical or ventricular branch; n, Its tion into two convex sections, _ horizontal or auriculo-ventricular branch; 0, Ven- each of which corresponds to. tricular branch of the cardiac vein; p, Auriculo- 9) auricle, The anterior, or ventricular branch of the same. right section, shows the in- sertion of the anterior vena cava and vena azygos; the posterior, or left, — that of the pulmonary veins. The trachea, bronchi, and pulmonary a pass above this face (Figs, 258, 259). The right face, the most extensive in the antero-posterior direction, is _ divided like the preceding, and disposed in a similar manner. The right, or anterior part, receives, behind and below, the insertion of the posterior vena | cava, and the coronary and bronchial veins (Fig. 259). \ Z A ( Leo oblique from above to below, — | i ; } THE HEART. 503 The left face, concave from before to behind, includes the arterial trunks which leave the base of the heart. Each of the extremities, anterior and posterior, constitutes a detached portion, named the appendix auricularis ; these appendages are curved towards each other in being flattened from above to below. Their convex border is more or less crenelated, like the margin of a cock’s comb, and their culminating portion advances nearly to the pulmonary artery, above the trunk of the cardiac vessels (Fig. 258). The base of the auricular mass, opposed to the base of the ventricles, is separated from it at its periphery by the horizontal groove of the heart. 3. Internal Conformation of the Heart. P ion.—It suffices to make a longitudinal incision before and behind the organ, in order to expose its cavities. (I have followed Wilson's directions for many years whe n examining the interior of the heart, and as a careful inspection of it is often necessary in the course of an autopsy, I think the student should practise the best method of laying open these cavities. The right auricle is p by making a transverse incision along its ventricular margin, from the ss try to its right border, and crossed by a perpendi- cular incision, carried from the side of the anterior to the posterior cava. The right ventricle is laid open by making an incision parallel with, and a little to the right of, the middle line, from the pulmonary artery in front, to the apex of the heart, and thence by the side of the middle line behind to the auriculo-ventricular opening. The interior of the left auricle is exposed by a | -shaped incision, the horizontal section being made along the border which is attached to the base of the ventricle. The latter is opened by making an incision a little to the left of the septum ventriculorum, and continuing it around the apex of the heart to the auriculo-ventricular opening behind.) Tf the heart, when viewed externally, appears to be a single organ, it is not so when examined internally. The vertical septum which divides it into two bilocular pouches, in reality makes two hearts of it—one for the dark, the other for the red blood. We will successively study these two cavites by commencing with the partition that separates them. _ A. Carprac Seprum.—The superior part of this septum, placed between the two auricles, is named the interauricular partition (septum auricularum). The inferior portion constitutes the interventricular partition Negras ven- triculorum). ‘The first, thin and not extensive, is perforated in the foetus by the foramen of Botal (foramen ovale). The second, thick in its centre, thins a little towards its borders. B. Darx-sioop (or Punmonary) Heart.The two superposed cavities forming this pouch are situated in front and to the right. They are indif- ferently named the anterior or right cavities of the heart: the latter term being in most general use, though the first is much more convenient in Veterinary Anatomy. Rieut Venrricte.—The right ventricle represents a hollow cone, the horizontal section of which resembles a crescent, its posterior plane being pushed into the cavity by the left ventricle. It offers two walls, an apex, and a base. Walls.—T he anterior wall is concave ; its thickness is more considerable above than below, and averages 6-10ths of an inch. The posterior wall is convex, and formed by the septum ventriculorum. Both walls are uneven, from the presence of fleshy columns (columnx carnese), which we will commence examining in a general manner, as they are found in the four compartments of the heart. They are of three kinds: one kind, named the pillars of the heart (columns or musculi papillares), thick and short, and fixed by their base to the walls uf the ventricles, have a free / 504 THE CIRCULATORY APPARATUS. summit, into which are implanted the tendinous cords (chorde tending) proceeding from the auriculo-ventricular valve ; those of the second order are free in their middle part, and attached by their extremities to the walls of the heart; while the third description adhere throughout their length to the cardiac tissue, on which they stand as if sculptured in relief, In the right ventricle, two columns of the first order, rarely three, are met with: one on the anterior wall, the other on the posterior, The columns of the second order num- ber two or three principal ones, ex- tending from one wall to the other, or attached to two different points of the same wall. There also ex- ist a considerable number of small ones intermixed with those of the third order. The latter are par- ticularly abundant in the angles Fig. 260. faces, where they interlace and give rise to more or less complicated areola. Apex.—The apex of the right ventricle does not descend to the point of the heart, being distant from it about 14 inches. RIGHT SIDE OF THE HEART LAID OPEN. formed by the union of the two 1, Cavity of right auricle ; 2, Appendix auri- culz, with musculi pectinati; 3, Anterior vena cava opening into the upper part of the right auricle; 4, Posterior vena cava ; 5, Fossa ovalis, surrounded by the annulus ovalis; 6, Eustachian valve; 7, Opening of the coronary sinus; 8, Coronary valve ; 9, Entrance of auricular-ventricular open- ing.—a, Right ventricle ; }, Its cavity; c, Conus arteriosus, or infundibulum ; d, Pul- monary artery; ¢, f, Tricuspid valve; g, One of the musculi papillares to which the curtains of the tricuspid valve are attached by chord# tendine ; 4, Columnz carnee ; i, Two musculi papillares of val- vular curtain ; /,7, Chorde tendinex ; m, Semilunar valves of pulmonary artery ; n, Apex of left appendix auricule; 0, Left ventricle. Base.—This is pierced by two large orifices—the awriculo-ven- tricular opening and the pulmonary opening. Auriculo-ventricular Placed on a level with the con- striction which divides the right heart into two superposed compart- ments, this orifice, widely open and almost a regular circle, forms the communication between the auricle and ventricle. It is provided with a valvular fold that exactly closes the orifice when the ventricle con- tracts to propel the blood into the lungs, and which is termed the tricuspid (having three points) valve, opening.— ~ , - - : wee Se in consequence of its form. This valve offers: 1, A superior border, attached - to the entire margin of the auriculo-ventricular opening; 2, An inferior opening, free, cut into three festoons by three deep notches, and fixed to the ventricular walls, principally on the summits of the fleshy columns, by means of tendinous cords which ramify on reaching the valve. One of these festoons, more developed than the others, is placed on the limit of the auriculo-ventricular and pulmonary openings; thereby constituting a kind of vertical partition which divides the ventricular cavity at its base into two compartments: a right or auricular, and a left or arterial. The other festoons are applied to the anterior and posterior walls of the ventricle; 3, An external face, which receives the insertion of a great number of — ee Ll ie — THE HEART, 1 505 tendinous cords; 4, An internal face, which becomes superior when the valve is raised to close the opening, at which period it constitutes the floor of the auricular cavity. Pulmonary opening—This orifice represents the embouchure of the pulmonary artery. Situated in front and to the left of the preceding, and a little higher, it occupies the summit of a kind of infundibulum formed by the left compartment of the ventricle being prolonged upwards. It is perfectly circular, smaller than the artery to which it gives origin, as well as the auriculo-ventricular opening, from which it is separated by a species of muscular spur, to which is attached the principal festoon Fig. 261. of the tricuspid valve. The ‘pulmonary opening is furnished with three valves: the sigmoid (or semicircular), sus- pended over the entrance to the pulmonary artery, and, as has been ingeniously remarked (by Winslow), like three pigeon’s nests joined in a_ triangle. These valves are remarkable for their thinness; a circumstance which does not interfere with their solidity. They present: an external, convex border, at- tached to the margin of the orifice and to the walls of the pulmonary artery; a free bor- der, straight when pulled tense, concave when left to itself, and sometimes provided in its middle SECTION OF THE HEART AT THE LEVEL OF THE with a small, though very hard, P, Pulmonary arte ra heck M, Mitral valve ; tubercle, the nodule of Arantius ”’ hg? Heaters Neca gh (noduli Arantii); a superior, coneave face; and an inferior, convex one. The sigmoid valves are raised and applied to the walls of the vessel whose entrance they garnish, when the ventricle contracts and sends the venous blood into the lung. When this contraction ceases, they fall back one against the other by that part of their inferior face next to their free border, so as to oppose the reflux of the blood into the ventricular cavity.’ 4 Rieur Avricie.—The cavity of the right auricle represents a very concave lid or cover surmounting the auriculo-ventricular opening, and is prolonged, anteriorly, by a curved cul-de-sac. It offers for study this anterior cul-de-sac, a posterior, external, and internal wall, as well as a superior ? It has been repeated, ad nauseam, that the occlusion of the arterial openings results from the juxtaposition of the free border of the sigmoid valves; even the small tubercle in the middle of this border has been considered to play its part in closing the triangular central space left when these valves meet. In passing the finger into the pulmonary artery of a living animal, to explore the function of these membranous folds, it is readily “anita that they come in contact by a large portion of their convex faee, and not alone y their free border. This arrangement is such, that we have with much difficulty tried to oe an insufficiency of contact by keeping one of the valves up aguinst the walls of the vessel with the finger; but the ahers came down against the finger and applied themselves around it so as to éxactly close the orifice. \ By 506 THE CIRCULATORY APPARATUS. wall or roof, and the auriculo-ventricular opening, which occupies the whole floor of the cavity. This orifice has been already described. The anterior cul-de-sac is in the appendix auricule; it is divided by a great number of muscular columns of the second and third orders (musculi pectinati), into deep and complex areole. The posterior wall responds to the interauricular septum ; it is smooth, and usually marked by an oblique and more or less deep cul-de-sac (or de- pression), the remains of Botal’s foramen. This depression is surrounded by the ring of Vieussens (annulus ovalis) and is named the fossa ovalis ; it is only separated from the left auricular cavity by a thin membrane, a vestige of the valve circumscribing the interauricular opening in the foetus. : The external wall is areolated, and perforated behind and below by two orifices, the largest of which is the embouchure of the posterior vena cava, the other the opening of the large coronary vein. Both are destitute of valves, though these are found at a short distance in the coronary vein. The bronchial vein sometimes opens separately beside the latter. The internal wall is smooth. The superior wall, or roof of the auricle, shows the openings of the anterior vena cava and vena azygos ; the latter only is provided with valves, which are, however, not always present. On this wall are also remarked, in front, areole separated by muscular columns. The thickness of the right auricular walls is very irregular, in conse- quence of the reliefs sculptured on the inner face of that cavity. In some points it is about the third of an inch, and in others, particularly in the small culs-de-sac formed by the reticulations, it is sometimes so thin as to appear exclusively formed by the union of the external and internal serous membrane. Sides the vena azygos opens behind, there is between it and the orifice of the anterior vena cava, a muscular lamella with a free concave border, which forms a kind of valve whose extent is very variable. Behind this vena cava is a thick eminence, the tuberculum Loweri; this has the form of a crescent, open in front, and elongated from right to left at the superior border of the septum. The anterior, or left border of the fossa ovalis, is thin and prominent, and constitutes the Eustachian valve: a museular membranous fold of a semilunar shape, with a concave free border directed to the right and behind. It is of little use in animals, because of their horizontal position. Immediately beneath the posterior vena cava, and between it and the coronary vein, is a small membranous crescent—the valve of Thebesius.) C. Rep-stoop (or Aortic) Hzart.—This is also called the posterior heart, and more frequently the left heart, because it is situated behind and to the left of the dark-blood heart. Its general disposition otherwise exactly resembles that of the latter receptacle. Lerr Ventrictr.—This is a cylindro-conical cavity, whose transverse section gives an irregularly circular figure. Its walls attain a thickness of from 1} to 1% inches, except towards the apex of the heart, where they are extremely thin. They are less reticulated than those of the right ventricle, and exhibit several columns of the second order, as well as two enormous muscular pillars—an external and internal, for the attachment of the tendons of the auriculo-ventricular valve. The apex of the cavity forms a re- ticulated cul-de sac, which occupies the point of the heart. The base is perforated by the auriculo-ventricular and the aortic openings. The auriculo- ventricular opening, precisely similar to that of the right ventricle, is — ee THE HEART. 507 provided with a circular membrane, the mitral (or bicuspid) valve, because it is cut into several festoons, of which two are the principal: the one anterior, the other posterior, simulating in their outline the two faces of a bishop’s mitre. The anterior festoon is the largest, and is attached to the limit of the two orifices, isolating from Fic. 262 the ventricular cavity a diver- isnt ticulum which corresponds, in every respect, to the pulmonary infundibulum. The posterior festoon is applied to the walls of the ventricle. Between these two there are usually two second- ary festoons, making up the total number to four; fre- quently there is an accessory fold, situated on the right side, and fairly developed; the valve is then tricuspid, like that of the right ventricle. Sometimes two of these rudimentary folds are found on the left side SSSSS —making five festoons in all. LEFT CAVITIES OF HEART LAID OPEN, The aortic opening, so named 1, Cavity of left auricle; 2, Cavity of appendix because it constitutes the origin auricule ; 3, Opening of two right pulmonary f th 5 ] rea veins; 4, Sinus into which left pulmonary veins . e aorta, 1s p sen open; 5, Left pulmonary veins; 6, Auriculo-ven- and to the left of the auriculo- tricular opening; 7, Coronary vein lying in ventricular opening, from which auriculo-ventricular groove; 8, Left ventricle; it is only separated by a thin 2% 9, Cavity of left ventricle—«, Mitral valve, . . its curtains connected by chorda tendinz to b, b muscular spur, to which is at- Columnz carnew; c, c, Fixed columne carne tached the adherent border of on inner surface of ventricle; i, Point of appendix the great festoon or curtain of of right auricle. the mitral valve. It does not differ in anything from the pulmonary opening, and like it, is provided with three sigmoid valves. Lxerr Avricirx.—As in the right auricle, this forms a kind of cover above the auriculo-ventricular opening. Smooth behind, in front, inwards and outwards, its cavity presents a reticulated cul-de-sac, which occupies the appendix auricule ; and a superior wall, also reticular, having from four to cight orifices, the openings of the pulmonary veins. These orifices have no yes. (Carnew columne of the third kind are also present, but chiefly between the two posterior pillars; small ones are very numerous on the borders and summit of the ventricle. The columns of the second order are simple or ramous, and pass from the angles of union of the walls and the point of the cavity ; others on the posterior wall go to the borders and the interval between the two pillars. The most remarkable are bands extending from one wall to the other, the two principal of which are long, strong, and ramous; they are fixed, on tke one side, to the centre of the great posterior reliefs, and ascend to be implanted, on the other side, into the middle of the anterior wall.) 4, Structure of the Heart. Preparation.—Before proceeding to dissect the muscular fibres of_the heart, it is indispensable to keep that viscus in boiling water for half or three-quarters of gn hour. It should then be immediately immersed in cold water, to prevent the desiccatif a of the 508 THE CIRCULATORY APPARATUS. serous membrane covering it, and which must be at once removed. The furrows should then be cleared of their vessels and fat; this renders the superficial muscular fibres very apparent. The same result may be attained by immersing the heart in vinegar or dilute ydvodilonte acid. To isolate the ventricles and unitive fibres from each other. the following ater may be adopted: After removing the auricular mass and dissecting the fibrous rings, the unitive fibres around these are divided with the point of the scalpel, care being taken not to injure the proper fibres. Then, with the aid of the finger-nail or handle of the scalpel, follow the more or less artificia] limit of these two series of muscular planes in a spiral manner; the vessels passing through the walls of the heart must be cut through. The same course is followed in the substance of the interventricular septum, in order to separate the two sacs formed by the proper fibres. (It will be found that the simplest and best way to prepare the heart for an examina- tion of its fibres, is to steep it in a very weak dilution of hydrochloric acid. Remove the serous membrane, and the fibres can then be traced, layer by layer, from their origin to their termination.) The muscular tissue composing the heart rests on a fibrous framework, disposed in rings around the auriculo-ventricular and arterial openings; it receives vessels and nerves, and while covered in the internal cavities by two independent serous membranes, it is enveloped, externally, by another membrane of the same kind. An annular framework, muscular tissue proper, vessels and nerves, and serous tunics—such are the elements entering into the organisation of the heart. : A. Frsrovs Rixes.—These are also named the fibrous zones of the heart, and are four in number: one for each of the openings at the base of the ventricles. The two arterial zones (the pulmonary and aortic) constitute two complete rings, which are not disposed in a circular manner around the pulmonary aortic openings, but are divided into three regular festoons with their con- cavities superior and internal, and which correspond to the insertions of the three sigmoid valves. 'These zones are continuous, by their superior and external contour, with the walls of the arteries, from which they are only dis- tinguished by their whitish-grey colour and slight elasticity, the arterial tissue being yellow and very elastic. Their internal and inferior outline sends three thin prolongations into the serous duplicatures of the sigmoid valves. The auriculo-ventricular zones do not completely surround the openings they circumscribe. They are flattened, brilliant-white tendons, laid one against the other at the level of the ventricular septum, and against the aortic ring; they turn to the right and left around the auriculo- ventricular openings, but without joining at their extremities, which are dispersed as fibrille in the muscular tissue of the ventricles. Above, these zones give attachment to the muscular fibres of the auricles; below, to the ventricular fasciculi. Their internal and inferior border is prolonged into the mitral and tricuspid valves, and is continuous, through these valves, with the tendinous cords fixed to the walls of the ventricles, Some of these cords, generally the strongest, are even directly inserted into the auriculo- ventricular zones. é It must be noted that, in Solipeds, there is constantly found, at the point where the aortic and auriculo-ventricular zones lie against each other, a more or less developed cartilaginous body, which, in the larger Ruminants, is transformed into true bone. (Lavocat speaks of two cartilaginous points, one to the right, at the junction of the aortic with the left auriculo- _ ventricular ring and the cardiac septum; the other, less developed, on the left, at the origin of the left ventricular groove.) _ B. Muscutar Tissuz.—The muscular tissue composing the mass of the THE HEART, 509 heart belongs to the system of organic life, as it contracts without the participation of the will. Nevertheless, it is formed of red striated fibres, which only differ from the muscular fibres of animal life in being less in diameter. As in the tongue, these fibres also possess ramifications that unite them to each other; they are likewise very granular. (They are more friable than those of the muscular system generally; the sarcolemma is more delicate, and the longitudinal markings and nuclei are more apparent, the latter being placed in the axis of the fibre along with rows of minute fatty granules, which are extremely numerous in fatty degeneration of the heart. The connective tissue is scanty ; so that the fibres lie closer together while forming innumerable anastomosing networks and interlacings—a character peculiar to the muscular organisation of the heart. It has been asserted that there is no sarcolemma.) The striation of the muscular fibres of the heart, Fig. 263. which constitutes an exception in the laws of organisa- tion, may be explained to a certain point by the nature of the functions imposed on the muscular tissue of the organ. Charged to propel the blood into the arterial ramifications by successive, instantaneous, and. vigorous contractions, the heart, probably, would not have been capable of executing such movements if it had been com- posed of organic fibres, as these come into action in a steady, slow, and prolonged manner. The ramifications that unite the fibres, and establish a kind of solidarity between them, afford a clue to the simultaneousness in the movements of the auricles and ventricles. It is also worthy of remark, that between these fibres there is so little connective tissue that the majority “* (NT nnn us on of anatomists absolutely deny its existence. | BEE . The arrangement of the muscular fasciculi of the heart has been the object of numerous recent investigations, which have only complicated what was already known on the subject. We will endea- vour to sum up, as simply as possible, this arrangement, in examining it in the different compartments of the organ. The following is the disposition of the fasciculi, considered successively in the ventricles and auricles : 1. Fisres or tue Ventricites.—According to the remark of Winslow, we may compare the ventricles, in regard to the arrangement of the fibres essentially composing them, to “two muscular sacs included in a third :” that is to say, each ventricle is formed of proper muscular fibres, covered externally by a layer of unitive fibres, which envelop the two ventricles in common. a. Proper fibres of the ventricles.—Taken altogether, these fibres repre- sent, for each cavity, a hollow cone, open at both its extremities: at the superior extremity, by the auriculo-ventricular and arterial orifices; and at the inferior extremity, by an aperture which admits the reflected fibres of the common layer. All form loops attached, by their extremities, to the out- line of the superior orifices, oi the fibrous zones, and are rolled, more or less obliquely, around the axis of the ventricles. It is from the apposition of the right and left systems that the ventricular septum is formed. b. Unitive fibres of the ventricles.—These are disposed as an external shell enveloping the proper fibres. They leave the fibrous zones at the base of the heart, and descend towards its apex : those of the right side>by inclining forward ; the anterior, in following the direction of the great axis qf the 510 THE CIRCULATORY APPARATUS, ventricles ; those of the ‘left face, by directing their course from above to below, and before to behind; and the posterior, in rolling themselves from left to right around the left ventricle. On arriving near the point of the heart, they turn from left to right, and before to behind, in forming a twisted spire; then they are reflected from below upwards, to enter the inferior extremity of the ventricles, on the internal face of whose proper fibres they spread and ascend to the fibrous zones at the base of the heart, where they terminate. Some of these reflected fibres are disposed in relief to constitute the columne carner, and reach the auriculo-ventricular zones through the medium of the tendinous cords which directly connect these fibrous rings with the summits of the muscular pillars. Such is the general disposition of the unitive fibres of the ventricles ; and it will be seen that they form a superficial and a deep or reflected plane, between which are comprised the fasciculi proper to each ventricular pouch. The unitive fibres of the ventricles, therefore, form collectively a kind of figure 8, the smallest loop of which is at the point of the heart; there the fibres are heaped together, leaving in the centre of the loop a very small space, through which it is possible to pass a probe into the ventricle, without piercing anything but the external and internal serous membranes of the organ. eo. Fisres or tHe Avricies.—The fibres of the auricles are either common to the two cavities, or proper to each. The unitive fibres con- stitute two thin bands—a right and left, carried from one auricle to the other. The proper fibres are divided into several fasciculi, some of which are arranged in rings around the auriculo-ventricular opening; others in inter- woven loops, and others, again, in sphincters, which surround the embouchures ofthe veins. These fibres are arranged in such a manner that, in contracting, they diminish the auricles by their superior and lateral planes and ex- tremities, and propel the blood towards the auriculo-ventricular openings. (The arrangement of the muscular fibres constitutes the most remarkable feature in the anatomy of the heart. We have seen that the auricles, as well as the ventricles, possess not only fibres proper to each compartment, but also unitive or common fibres which assure the simultaneousness in action ~ of the similar or homologous cavities. Besides, the fibres of the auricles and those of the ventricles are distinct, and not continuous; so that, from their independence of each other, it results that these two sections of the heart may act separately, and contract, not simultaneously, but alternately, a con- dition indispensable to the free course of the blood. The extremely fine and close connective tissue uniting the muscular fibres, is another peculiarity of structure that must be favourable to the solidarity of their action, which ought to be simultaneous. Adipose tissue is only found in the grooves on the surface of the organ, around the vessels lodged in them, and particularly at its base, between the large arterial trunks. ) ©. Vessets anv Nerves or tHe Heant.—Blood is carried to the muscular tissue of the heart by two large vessels, the coronary arteries. They emanate from the trunk of the aorta, at the sigmoid valves, and each divides into two principal branches: one passing along the horizontal, the other in the vertical furrow of the heart. Collectively, these arteries form two circles, which surround the heart in intersecting it at a right angle in the auriculo- ventricular groove. The blood is carried from the walls of the heart by a single but impor- tant vein, which empties itself into the right auricle. : | } | ee this tint is slightly yellow, especially in the walls of THE HEART, . 511 S Gea lymphatics follow the arteries, passing along the visceral layer of icardium, and entering the cluster of glands situated near the base of = (The endocardium, especially in the ventricles, has a network of fine sil et the walls of which consist of only a single layer of intimately-adhering cells. None have been traced upon the chorde tendinee, and very few upon the auriculo-ventricular and semilunar valves.) The nerves of the heart, furnished by the cardiac plexus, come from the ic and sympathetic. ‘The tubes are small, and show some cells in their course. In addition to these, the heart is provided with a particular see system, to which Remak has called attention. It is believed that there exist three ganglia in different points of the cardiac parietes, and that on these depend the movements of the organ. (According to Carpenter, the nerves of the heart are: 1, Minute ganglia and fibres of the sympathetic, situated in the walls of the cavities, and especially in the auriculo- ventricular furrow; 2, Fibres derived from the cervical portion of the sympathetic, and passing to the cardiac plexus, between the aorta and onary artery ; 3, Cerebro-spinal fibres entering the inferior cervical or stellate ganglion, and proceeding to the same plexus, and probably derived from a centre situated in the brain and spinal cord; and, 4, Fibres coursing in the vagus, and originating in a centre situated in the medulla oblongata. The first three of these ganglia and fibres probably collectively con- stitute the excito-motor system of the heart, the fourth is an inhibitory, ining, or regulo-motor centre.) D. Szrovs Mempranes or tHe Hxrart.—These are three in number : two internal, or endocardial, one of which occupies the right, the other the left cavity; and an external, a dependency of the fibro-serous sac which contains the heart. 1. Internal serous membranes, or endocardia—These two membranes, independent, like the cavities they line, are spread over the auricular and ventricular walls, covering the tendinous or muscular columns attached to these walls, and are prolonged into the veins and arte- Biv. 904 ries, to form the internal tunic of these vessels. At ore the auriculo-ventricular and arterial openings, they con- RECO, stitute a duplicature for the valves situated there. These valves are, therefore, due to the projection of a circular fold of the endocardia, between the two layers of which a thin prolongation of the fibrous zones from the base of the heart is insinuated. In the auriculo- ventricular valves there is also found, beneath the internal or superior layer, muscular fibres furnished by the auricles. The endocardium of the right heart has a red tint, which is deepest in the ventricle. In the left heart, the auricular appendix, which may be attributed to the presence of a thin layer of yellow elastic tissue that covers the adherent face of the membrane. EPITHELIUM OF THE e endocardium consists of three layers: 1, A ENDOCARDIUM, thin bed of white fibrous tissue, connecting it to the 1, Nucleated cells as- ing the fusiform muscular structure; 2, A middle layer, composed of fet goa Polygonal elastic tissue which is very abundant in the auricles; py ih wee and 3, An epithelium, consisting of a single or double layer of somewhat elongated, polygonal, pavement nucleated cells.) 512 THE CIRCULATORY APPARATUS. 2. External serous membrane.—This is the visceral lining membrane of the pericardium, the description of which follows. 5. The Pericardium. (Fig. 234, o.) Preparation.—Place the animal in the second position, and remove the sternal ribs by separating the cartilages and luxating their costo-vertebral articulations. This pro- cedure permits the study of the situation and general disposition of the heart and pericardium, But in order more easily to examine tlie reciprocal arrangement of these — two parts, it is necessary to extract them from the thoracic cavity by tearing through the sternal insertion of the. pericardium. The pericardium, or proper serous membrane of the heart, is a membranous sac inclosing that organ, fixing it in the thoracic cavity, and fayouring its movements by its polished surface. This sac is formed by a fibrous layer, within which is spread a serous membrane, divided into two parts—one parietal, the other visceral. The fibrous layer of the pericardium presents somewhat the general form of the heart. Its internal surface is covered by the parietal portion of the serous membrane. The external surface corresponds to the two laminw of the mediastinum. Its summit (or apex), depressed on each side, and elon- gated from before to behind, is firmly attached to the superior face of the sternum, from the fourth rib to the origin of the xiphoid cartilage. By its base, it is fixed to the large vessels going to and leaving the heart, where it is continuous with their cellular sheath, and where it sends some fibres to the longus colli. The serous membrane of the pericardium has been well compared by Bichat to a cotton night-cap, the external part of which would represent the parietal layer, and the inverted part the visceral division of that membrane. — The parietal layer adheres in the most intimate manner to the internal face of the fibrous tunic, and is seen to be reflected, to form the visceral portion, around the pulmonary arteries and the aorta to a certain distance from their origin, and on the pulmonary veins. The visceral layer enyelops in common the two arterial trunks, covers a small part of the venm caym, particularly the anterior, spreads over the insertion of the pulmonary veins, and then descends on the auricles and ventricles. The free face of this layer is in contact with that of the parietal layer; the adherent face is applied to the tissue of the heart or that of the large vascular trunks, except at the horizontal and vertical grooves, where it rests on the coronary vessels, and on the mass of adipose tissue constantly accumulated on their track. In the living animal, the cavity of the pericardium is never entirely filled by the heart, whose movements are, therefore, allowed much more liberty. Otherwise, as it does not contain any gas, nor a sensible proportion of fluid,’ its walls are immediately applied to the surface of the heart. Blood reaches the pericardium by the mediastinal arteries. Its walls receive some sympathetic nerve-fibres. The pericardium is composed of a fine network of elastic fibres adhering to the muscular structure of the heart by one surface, and covered by a single or double layer of tesselated epithelium on the other. Gurlt, in 1867, ! With horses in health, the fluid exhaled into the pericardium is barely sufficient to moisten and lubrify the free surface of its serous membrane. But in those worn-out and enfeebled by age, privations, or disease, it is not rare to see it accumulated in greater or less quantity. ‘To verify this, however, an examination ought to take place immediatel after death, as the accumulztion of fluid in the serous cavities by cadaveric exhalation common in all animale, THE HEART. 513 described a thin muscle, nine inches long, situated between the pericardium and the diaphragm of the Horse.) 6. Action of the Heart. The function of the heart is to maintain the circulation of the blood, by the rhythmical contractions of its two pouches. The right pouch sends that fluid to the lungs, whence it returns to the left pouch, and from this it is thrown into all parts of the body, and is brought back again to the right heart. These contractions take place simultaneously in the two cardiac com ents. taking the heart at the moment when it is in a state of repose: that is, in the intervals between the two contractions, we find that its two pouches are being rapidly filled with the blood brought to it by the venous openings. When sufficiently replete, the auricles slightly contract and push a portion of the fluid they contain intot. ventricles: these contracting immediately after, to propel the blood into the u.*-vial ramifications. This- passage of the blood into the arteries is a necessary consequence of the contraction of the ventricles, as at the moment of this contraction the auriculo-ventricular valves are raised, and so prevent the reflux of the blood into the auricles. This fluid is then forced to enter the arterial orifices, whose valves are separated under the impulsive effort communicated to the column of blood. When the heart returns to a state of repose, these yalves fall down, preventing the return of the blood into the ventricular cavities ; while the mitral and tricuspid valves subside against the walls of these cavities, and thus again allow the passage of blood through the auriculo-ventricular openings. 3y the term systole is designated the contraction of the heart’s cavities, and by diastole, the repose or relaxation of its tissue. For each revolution of the heart there is, therefore: 1, The general diastole of the organ, during which the two cardiac cavities are filled by the afflux of venous blood; 2, The systole of the auricles, the effect of which is the repletion of the ventricles ; 3, The systole of the ventricles, propelling the blood into the arterial systems ; after which comes another period of general diastole. DIFFERENTIAL CHARACTERS IN THE HEART OF OTHER THAN SOLIPED ANIMALS, In the Oz, i and Goat, the ventricular mass of the heart is more regularly conical than in Solipeds; it has three longitudinal furrows, one of which is accessory and pay behind the (left) ventricle. the Oz two small bones, named bones of the heart, are found in the substance of the aortic zone. The largest is in the right side, at the point where the arterial ring is approximated to the auriculo-ventricular zones; the other, situated in the left, is perha not constantly present. The first is triangular in shape, curved to the right, and its base directed upwards. ‘he right face lies against the auriculo-ventricular opening ; the left is covered by the walls of the aorta at its commencement. It is about an inch in length. (The Ox’s Leart averages from about 3} to 44 lbs., that of the Sheep from ae 7oz. It is more elongated and pointed in Ruminants than in the Horse or Pig. e large bone in the Ox’s heart is elongated from before to behind, flattened laterally and curved to the left; its surtace is roughencd, and its length is sometimes about 2 inches. The left, or small bone, is usually flattened on each side and triangular, one of its points is directed forwards, another backward, and a third inferiorly ; its length is about three- —. of an inch when fully a Besides the (x, a small cross-shaped bone is in the heart of the Sheep, Pig, el, Deer, Giraffe, and sometimes in the Horse. Remak found in the pericardium of the Oz, at the border of the left auricle, a row of villi similar to those discovered in the border of the chicken’s heart.) The heart of the Pig resembles that of the Horse ; its direction is a little more oblique, 21 < ee 4 a x * e ng ; mei oe 5i4 , THE CIRCULATORY APPARATUS, = , _ a | and the pericardium is fixed to the sternum from the third rib to the xiphoid appendix. — as well eis the diaphragm. (The cartilage is not ossified untila lute period.) = In the Dog and Cat, the heart is oval or nearly globular. It is almost entirely resting — on the upper face of the sternum ; its anterior face has become the inferior, and its — point, directed backwards, touches the anterior surface of the diaphragm, The pericardium — is attached to the aponeurotic centre of the diaphragm. COMPARISON OF THE HEART OF MAN WITH THAT OF ANIMALS, The human heart is ovoid, and similar to that of the Carnivora; the ventricular mass is not acute at its apex, as in Fig. 265, Solipeds and Ruminants. Its _ direction Ne rages pare conse-— uence of the an | attening of the chest. It is situated across the ne of the thorax; its right face in- animals has become the anterior — face in Man, and is applied to the — sternum; the anterior border is— in lim the right border, and the posterior the left border. The organ is ob- | liquely downwards, forwards, and tthe left; consequently, the | auricle is to the right of the sternum, between the third and fourth ribs, and the point on a level with the sixth left inter- costal space. The auricular ap- pendages, particularly the right, — are more rounded and bulging than inanimals, The pulmonary veins, four in number, open on the upper face of the left auricle. — There are no essential differ-— HUMAN LUNGS AND HEART; FRONT VIEW. ences to be noted in tan taEaenats 1, Right ventricle ; 2, Left ventricle; 3, Right auricle; conformation. We may i | 4, Left auricle; 5, Pulmonary artery; 6, Right the presence of a fold that Laeger pulmonary artery; 7, Left pulmonary artery; 8, from the ring of Vieussens to the | Ligament of ductus arteriosus ; 9, Arch of aorta; opening of the inferior vena cava: 10, Superior vena cava ; 11, Arteria innominata ; 12, this is the Eustachian valve. We Right subclavian vein, with the artery behind it; may also mention the Thebesian 13, Right common carotid artery and vein; 14, Left valve at the entrance of the coro- vena innominata; 15, Left carotid artery and vein; nary vein. . 16, Left subclavian vein and artery; 17, Trachea ; The fibrous rings and museular 18, Right bronchus; 19, Left bronchus; 20, 20, fasciculi are disposed as in the Pulmonary veins; 21, Superior lobe of right lung; Horse. 22, Middle lobe ; 23, Inferior lobe ; 24, Superior lobe The pericardium is a conical of left lung; 25, Inferior lobe. sac; but instead of its base | presented upwards, it rests | the aponeurotic centre of the diaphragm ; its summit is lost among the large vesrels, and it adheres to the posterior face of the stemnum, | [ 515 } SECOND SECTION. THe ARTERIES. CHAPTER I. GENERAL CONSIDERATIONS, Tue name of arteries is given to the centrifugal vessels, which carry the blood from the heart to the various organs. These vessels proceed from the heart by two trunks, which are perfectly independent in the adult animal; they originate, one in the right ventricle, the other in the left. The first of these trunks, destined to carry the dark blood, is the pul- artery. 'The second conveys the red blood, and is named the aorta. There exist, therefore, two groups of arteries; the pulmonary system, and the aortic system. Generat Form.—Single at their origin, the two arterial systems soon divide into less voluminous trunks, which again subdivide into successively decreasing canals, until at last their diameter becomes reduced to an extreme of tenuity. In a word, the arterial trunks present the ramous dis- position of dicotyledonous plants. The total volume of the secondary trunks exceeds that of the primary trunk, and the same relation exists between the ive dimensions of the branches and their ramifications, to the ultimate divisions of the artery. In tracing all the ramifications of one of these systems to a single canal, it will then be found that this canal is incessantly increas- ing from its origin to its termination, and that it represents a hollow cone whose apex corresponds to the heart. Form or THe Arrertes.—Each arterial tube affects a regularly cylin- drical form, whatever its volume may be. When the diameter of these vessels is measured at their origin and their termination, between two collateral branches, no sensible difference is perceived. Mopz or Oriarn.—The arterial ramifications are detached in an angular manner from the parent branches which give them crigin. Sometimes the angle of separation is more or less acute—this is most frequently the case; sometimes it is at a right angle, and at other times it is obtuse. It will be readily understood that the opening of this angle exercises a somewhat marked influence on the course of the blood ; for example, the blood from @ principal vessel, in passing into the canal of a secondary one which springs from it at an obtuse angle, must experience a notable check in its impetus, because of the change in direction it has to encounter; on the contrary, the rapidity of the current is not modified to any appreciable degree in those vessels which separate from their trunk of origin at a very acute angle. Towards the point of separation, there is always remarked, in the interior of the vessel,a kind of spur whose sharp border is towards the heart, thus dividing the current of blood and diminishing the resistance. This spur resembles in its disposition the pier of a bridge, against which the waters are divided to pass on each side. (When a short trunk divides abruptly into several branches, proceeding in different directions, it is termed an axis. A y peculiar feature in the division of arteries, however, and one which will be 212 516 THE ARTERIES, made amply conspicuous in the following description, is their bifurcation or dichotomous arrangement, which prevails so largely.) Coursr.—In the course pursued by an artery, it is necessary to consider the situation occupied by the vessel, its direction, relations, and the anastomoses which establish communication between it and the neighbouring vessels. Situation.—The arteries tend constantly to recede from the superficial parts: to become lodged in the deep-seated regions, and in this way to be removed from the hurtful action of external causes, a tendency all the more marked as the arteries are more considerable in volume, and which ceases to be manifested in the less important ramuscules. These vessels, therefore, occupy either the great cavities of the trunk, or the deep interstices on the internal face of the members; when they pass over an articulation, it is always on the side at which flexion occurs. But in the limbs, for instance, the joints are flexed alternately in opposite directions, and it then happens that the arteries in these regions have a slightly helicoid (or spiral) disposi- tion. This is evident in the case of the femoral artery, which passes round the inner face of the femur to become the popliteal artery ; and also in the humeral artery, which is at first situated to the inner side of the scapulo- humeral articulation, then turns around the humerus to be placed in front of ! the elbow joint. Direction.—The arteries are sometimes rectilinear, and at other times more or less flexous. The latter disposition is evidently intended to prevent the dilaceration of the vessels in organs susceptible of elongation and con- traction, as may be remarked in the tongue; or to moderate the impetus of the blood, as in the internal carotid arteries. Relations.—In their course, the arteries may be in contact with the viscera, nerves, muscles, bones, skin, and connective tissue. a. In nearly every part of the body, the arteries maintain-the most intimate relations with the veins: sometimes with two of these vessels, when the artery is placed between them ; sometimes with only one, which is always more superficial. b. The arteries are usually accompanied by nerves belonging to the cerebro-spinal or ganglionic systems. Those of the latter category are distinguished by the reticular interlacing they form around the visceral arteries ; their structure will be alluded to presently. c. Lodged for the most part in the interstices of the muscles, the arteries contract relations with these organs which it is very important to know in a surgical point of view. Some of these muscles lie parallel with important arteries, and for this reason have been designated satellite muscles; they serve to guide the surgeon in searching for the arteries, by the more or less salient relief their presence affords beneath the skin. It is worthy of remark that the arteries are not included in the fibrous sheaths enveloping the muscles; these vessels nearly always occupy, with — the nerves which accompany them, special lodgments resulting from the approximation of several aponeurotic sheaths. When they pass through the substance of a muscle, which sometimes happens, they are covered by an arch or fibrous ring, which protects them from compression during muscular contraction: the arch or ring receiving on its convexity the insertion of fibres from the muscle. d. Nothing is more common than to see the arteries in direct contact with the bones: as, for instance, the aorta, intercostals, &e. Neither is it very rare to find a more or less thick muscular layer between the arteries and portions of the skeleton. In every case, a knowledge of the connections ; ad ill a le nn . ‘ 4 £ 4 7 b GENERAL CONSIDERATIONS, 517 of the arteries with the bones is important to the surgeon; as it enables him, temporarily, to interrupt the circulation in these vessels by exercising external pressure on the points of their course which correspond to the several bones, and thus diminish their calibre by flattening them. e. By virtue of their deep situation, the arteries are, in general, distant from the skin ; there are, nevertheless, some which course immediately beneath the inner face of that membrane; these are only found about the head and in the extremities. f. Lastly, all the arteries are enveloped by a layer of connective tissue, which forms around them a kind of sheath, generally difficult to tear with the fingers alone, and which isolates from the neighbouring parts, but chiefly the veins. This connective tissue, more or less abundant according .to the regions, is always loose enough to allow the arteries to roll and be displaced with the greatest facility, and thus to glide away from incisive bodies accidentally introduced into the tissues, Anastomoses.—V ery often the arterial branches are united to each other by communications, which have received the name of anastomoses, and which assure the distribution of the blood in regulating its flow. There are istincuished « 1. Anstomoses by convergence : formed by two vessels joining at their terminal extremity in an angular manner, to form a third and more voluminous trunk. 2. Anastomoses by arches or by inosculation: due to the junction of two principal branches, which are inflected towards each other, meet, and unite to form a single and curvilinear canal. 3. Anastomoses by transverse communication : represented by ramifications thrown transversely between two parallel arteries. 4. Mixed or composite anastomoses: in which are found a combination of the different types enumerated above. A knowledge of the anastomoses of vessels is of the highest practical interest; as these communications permit the surgeon, in extreme cases, to tie the principal artery of a region without the latter experiencing any considerable nutritive disturbance; the blood continuing to arrive by the collateral vessels which, at first very small, gradually dilate from the excentric pressure to which their walls are submiced. But these anasto- moses, if they offer this immense advantage, have also their inconveniences : we allude to the difficulties experienced in arresting hemorrhage in wounds of certain organs, owing to the relations of the principal vessel with its communicating collaterals. Move or Disrriwsvurion.—The branches an artery distributes in the neighbouring organs are distinguished as terminal and collateral. The arterial trunks, after finishing a certain course, divide into several branches— nearly always two, which, as new arteries, continue the primary vessel and take the name of terminal branches, because they really begin at the terminal extremity of that vessel. The collateral vessels originate at various distances along the course of the arteries, and proceed in a lateral direction: these collateral branches increase in number as the arteries become more superficial, the ramifications being particularly abundant around the articulations, and in the organs which are prominent on the surface of the body. This abundance of vessels is intended to maintain a moderate temperature in those parts which, by their structure or situation, are exposed to sudden chills. The distinction between the terminal and collateral branches of arteries 518 THE ARTERIES. is not always easy to establish, and is far from having an absolute value; it nevertheless, some importance, as it greatly facilitates Termination.—The arteries terminate in the substance of the . by extremely fine and numerous ramuscules, which so frequently anastomose with each other as to form a plexus or microscopical network, whose meshes Fig. 266. WEB OF FROG’S FOOT STRETCHING BETWEEN TWO TOES, SHOWING THE BLOOD- VESSELS AND THEIR ANASTOMOSES, a, a, Veins; b, b, 6, Arteries, the capillaries being between. are very close. These ramuscules constitute the capillary system, which again gives rise to ramifications of gradually increasing size, the veins. The capillary system is, therefore, nothing more than Fig. 267. a network of microscopical canals intermediate to the 7] arteries and veins. n In the erectile tissues, the mode of termination is y, different: the small arteries sometimes opening directly into the cells placed at the origin of the veins, without passing through a capillary plexus, In describing the genital organs we shall notice, in detail, the termination of the arteries in the cavernous tissues. Srructurs.—The walls of arteries offer a certain rigidity, which permits these vessels to remain open when they are emptied of blood. The ancients believed EPITHELIAL CELIS OF this was their normal condition, and that they were BLOOD-VESSEIS, —_—_ filled with air during life. This was a grave error, as 4 Petsson ed ea °* a perfect vacuum exists throughout the entire circulatory Magnified 350 dc. System. The gaping of the arteries must be attributed meters. solely to the physical properties of their walls. ese wails comprise. three superposed tunics; an internal, middle, and external. The internal tunic is continuous with the endocardium of the left heart GENERAL CONSIDERATIONS. 519 on the one part, and on the other with the capillaries and veins. For a long time it has been assimilated to a serous membrane, but it has not __ absolutely the same texture. It is composed of a simple epithelial layer _ which is in contact with the blood, and is formed by fusiform cells that Fig, 268, slightly bulge in the situation of their nucleus. These cells sometimes become detached, and are carried about in the nutritive fluid, in which, after a certain period, they resemble more or less mis-shapen blood- globules. The epithelium lies upon a layer of amorphous elastic tissue, perforated by openings, and named the fene- strated membrane ; on its ex- ternal face are proper elastic Fig. 270. FENESTRATED MEMBRANE FROM THE CAROTID ARTERY OF THE HORSE. fibres passing in a longitudinal direction. The middle tunic is remark- able for its thickness, its elas- ticity, and the yellow colour it offers in the principal vessels. Itis composed of a mixture of elastic fibres, as well as _ smooth muscular fibres, the first constituting a kind of network, in the meshes of which the contractile fibres are disposed in a circular manner around the vessels. : The proportion of these two elements varies with the size Magnified 350 diame- ters. TRANSITION OF A MINUTE Fig. 269. NETWORK OF COARSE BLASTIC TISSUE FROM MIDDLE COAT OF PUL- MONARY ARTERY OF THE HORSE, THE FIBRES BEING PIERCED WITH _ CIRCULAR OPENINGS. _ Magnified 350 diame- _ ters, as that just described, bu and situation of the artery. In the large trunks, such as the aorta, the elastic is more abundant than the contractile ; in the middle-sized vessels they are about equal; but in the small arteries, in which the contractile force of the heart is lost because of their distance from it, the muscular fibres almost exclusively com- pose the middle tunic. The external tunic is only a layer of connective tissue, with some longitudinal reticu- lated elastic fibres in its deeper part. Though this tunic is very thin, yet it is strong; as ARTERY OF THE BRAIN INTO CAPILLARY VES- SELS, 1, Minute artery; 2, Tran- sitional capillary; 3, Coarse capillary with thick coat, represented by a double contour line; 4, Fine capillary, with single contour. The nuclei are seen widely scattered in 4 and 3; more closely con- gregated in 2; and still more so in 1, where they form an epithelium.—a, Transverse _ elongated nuclei of muscular cells, the incipient muscular coat of the artgry. a ligature tied tightly around an artery will rupture the other tunics, but not this. The structure of the capillaries is not the same t is modified in proportion as they are fine. the smallest capillaries, the walls are formed by a thin amorphous mem- brane, in which (oblong) nuclei are somewhat regularly disseminated; in ium-sized yessels, another layer containing transverse nuclei is observed ; and in the largest capillaries—those immediately succeeding the small In 520 THE ARTERIES, 4 arteries, these two nucleated layers are enveloped by a thin tunic of con- nective tissue, (Some authorities state that the walls of the very finest capillaries are merely composed of closely-adhering cells, without any basement membrane, which only: becomes apparent in tubes of a large diameter.) Vessels and nerves—The arteries are provided with vessels termed vasa vasorum, which are furnished either by the arteries themselves, or by neigh- bouring vessels. These vasa vasorum form a superficial network with quad- rilateral meshes, and a deep plexus whose principal branches are helicoidal. The majority of anatomists believe that this plexus does not extend beyond the external tunic. The lymphatic vessels maintain intimate relations, in certain regions, with the capillaries. In the brain and spleen there has been discovered, around the arterial capillaries, a vessel that completely envelops them, and which has been named the lymphatic sheath. The nerves, designated vasa motors, accompany the vessels and penetrate the muscular tunic, for which they are naturally destined. These vaso- motor filaments join the branches of the capillary plexuses, and form, at the points where they meet each other, ganglionic enlargements, from which arise the fibres of Remak, the termination of which is unknown. ANoMALIEs In THE Artertes.—In their arrangement, the arteries very often present anomalies which the surgeon should be guarded against. These usually belong to their number, their point of origin, and their volume. Ina purely anatomical and physiological point of view, however, these anomalies are of no moment; as it matters little whether the blood comes from one source rather than another, or that a collateral vessel be- comes the principal at the expense of the parent trunk, provided its rela- tions are not altered, and the principle of immutability of connections is maintained. PREPARATION OF THE ARTERIES.—This requires two successive operations: 1, In- — jection; 2, Dissection. Injection of the arteries.—The object to be attained in injecting these vessels, is to introduce into their interior a solidifiable substance which will cause them to assume the volume and conformation they presented during life, when they are filled with bleod. Tallow, coloured by lamp-black, is the most convenient and general injecting mate- rial. Sometimes a solution of gelatine, with the addition of a certain quantity of plaster of Paris, is used; but this is seldom employed in the French schools. A copper or brass syringe, and a canula with a stop-cock to fit on its extremity, are the only instru- ments necessary to propel these matters into the arteries. The following are the details of the operation, when it is desired to make a general injection :—The animal being placed on a table, the carotid artery is exposed by an incision in the jugular channel, and opened longitudinally. A ligature is applied above the opening, and. the tube, with the stop-cock, is firmly fixed in the cavity of the artery towards the heart by a second ligature. The injection, previously prepared, is taken up by the syringe, which is fitted into the tube, and the piston pushed, in order to drive the contents of the instrument into the arterial canals. To perform the operation successfully, the following precautions are to be attended to: 1. Inject the vessels of an animal killed by effusion of blood, and yet warm. 2, If suet is employed, and which is always to be recommended, make it so hot that the finger can shasta endure it. When it is colder than this it solidifies too quickly, and when hotter it dalyels up the sigmoid valves, passes into the left ventricle, and from thence into the auricle and pulmonary veins; an accident generally attributed to the too power- ful force applied to the piston of the syringe. 3. Do not make any undue pressure on the piston, though this does not strain the sigmoid valves so frequently as is believed, 4. Cease injecting when the arteries react, by their elasticity, on the piston, so as to drive it in the syringe. In order to insure the retention of the injected matter in the arteries, and prevent the sigmoid valves being forced, a cork may be introduced into the aorta through the 1 PULMONARY ARTERY. 521 left ventricle, and firmly tied there by a strong ligature ; the cork should have a trans- verse notch for the reception of the ligature. Instead of injecting by the carotid, a long curved canula may be fixed to the aorta itself, after an opening in the left side of the chest, on a level with the heart, by the ablation of two — of the ribs, and incising the pericardium and left auricle to introduce it. This mode allows the tallow to be injected at a very high ture, and gives the best results, for it can then penetrate to the capillaries, if we ouly know how to manage it; in certain organs the injected matter may even be made to return by the veins. But no matter what procedure may be adopted, there are several parts into which the tallow can never be made to enter by a ese injection ; these are the four extre- mities. So that a special operation must be resorted to, in order to fill their vessels. After separating them from the trunk, by sawing them through above the knees and hocks, they should be allowed to steep for two hours in water, constantly kept up to a temperature of 140° to 160° Fahr. at most; it is then easy to inject them, either by the ior radial artery, or the anterior tibia!, after tying those branches which may be open at the cut pega f of the limbs. If it is desired to make partial injections in other parts of the body, it will be better not to separate them from the trunk; but only to tie those vessels which anastomose between the arteries to be filled and those which are not. For example, to inject the arteries of the head, it suffices to push the mixture into one of the common carotids, i ing the other in the middle of the neck, and both vertebrals in the space between the two portions of the scalenus muscle. We may give the tallow more fluidity, and a higher degree of penetration, by mixing with it a little spirits of turpentine ; or mure consistence, in adding to it a small proportion of beeswax. The two following mixtures are borrowed from Cruveilhier’s Anatomy :— Boor oe ce a8, See «I ee ee ae Pee % : Ivory Black, mixed with spirits of turpentine . 2 ,, For preservative injections :— PO Gosche cat tee te Reece fo DP pet , US es es Vermilion, indigo, or Prussian blue, previously mixed in spirits of turpentine. . . . . A sufficient quantity. Of course it is well understood that these instructions are only intended for the dissecting-room injections necessary for the study of descriptive anatomy. ‘To ivject the capillaries, it is requisite to have recourse to other substances and other procedures, Suffice it to say that these injections are made with cold fluids, such as varnish, alcohol, or spirits of turpentine, holding in suspension extremely fine colouring matter, gum arabic dissolved and coloured by a substance also in solution, etc., or, better still, colours rubbed up in oil, and mixed with spirits of turpentine, es Dissection of the arteries——There are no general rules to be given for the dissection CHAPTER IL. ; PULMONARY ARTERY (Fig. 258, e), Preparation.—The pulmo tery is not filled by the general injecti tioned above, It ia directly injected by propelling the tallow into the right heart by the anterior yena cava, after tying the posterior vena cava. The pulmonary artery springs from the infundibulum of the right ventricle, is directed upwards and then backwards, describing a curve whose coneavity is infero-posterior, and arrives above the left auricle, where it divides into two secondary arteries, one for each lung. These arteries enter the pulmonary tissue with the bronchi, and exclusively ramify in it. The pulmonary artery accompanies the trunk of the aorta on the right side, ad is enveloped with it in a serous sheath, a dependency of the visceral Jayer of the pericardium. At its origin, it is flanked before and behind by 522 THE ARTERIES. the appendages of the auricles and the cardiac vessels. About the middle of its course, it is united to the posterior aorta by means of a yellow elastic fibrous cord (the ligamentum arteriosum), the remains of the ductus arteriosus which, in the foetus, establishes a large communication between these two vessels (Fig. 258, e). | The walls of the pulmonary artery are much thinner than those of the aorta, and are yellow and elastic, as in the other canals of the same order. We remember, however, having seen them in an Ass, formed almost entirely of red muscular fibres, analogous to the fasciculi of the heart. It may be repeated that the pulmonary artery conveys into the lungs the dark blood carried to the right heart by the veins of the general circulation. CHAPTER III. THE AORTA. Ir we take a general survey of the aortic trunk, we will find that it arises from the base of the left ventricle, ascends to beneath the dorso-lumbar column, curving backwards and downwards, and reaches the entrance to the pelvis, where it terminates by four branches. It furnishes, besides, about 2 to 24 inches from its origin, a secondary trunk, which soon divides into two new arteries, the right and largest of which gives off a particular trunk, the common origin of the two long vessels destined for the head. This disposition permits us to recognise in the aorta seven principal sections : 1. The aortic trunk or common aorta: the source of all the arteries belonging to the red-blood system, and giving rise to the anterior and posterior aorta. It only furnishes blood directly to the heart itself. 2. The posterior aorta: the veritable continuation of the common aorta, is distributed to the posterior moiety of the trunk and to the abdominal limbs; it terminates by a double bifurcation. 3. The internal and, 4, external iliac arteries: branches of this bifureation which are almost entirely expended in the posterior limbs. 5. The anterior aorta: the smallest of the two trunks furnished by the common aorta, is chiefly destined to the anterior moiety of the trunk and the thoracic limbs. ; 6. The awillary arteries, or brachial trunks: these come from the bifurea- tion of the preceding artery, and are continued by their terminal extremity into the fore-limbs. 7. The carotid arteries, or arteries of the head: these emanate by a common trunk from the right brachial bifurcation. __ Articte I.—Aortic Trunk on Common Aorra. The point of departure for all the arteries carrying red blood, the aortic trunk proceeds from the left ventricle by becoming continuous with the festooned fibrous zone which cireumscribes the arterial orifice of that cavity. It passes upwards and a little forwards, bifurcating, after a course of 2 or 24 inches, into the anterior and posterior aortee. Its volume, inferior to that of its two terminal branches, is not uniform ; as at its origin, and opposite the sigmoid valves, it presents (an enlargement —the bulbus aortee—caused by) three dilatations described as the sinus of the aorta (sinus aortici, sinus Valsalvse). : THE POSTERIOR AORTA. 523 Included, on the right side, in the crescent formed by the auricular mass; in relation, on the left side, with the pulmonary artery, which is joined to it by means of cellulo-adipose tissue traversed by the ac nerves, the common aorta forms, with the latter artery, a fasciculus enveloped by the visceral layer of the pericardium, which is reflected as a sheath around these two vessels. Two collateral arteries are given off directly from the aortic trunk: these are the cardiac or coronary arteries. Cardiac or Coronary Arteries. (Figs. 258, 259.) There are two cardiac arteries, a right and left, exclusively destined for the tissue of the heart. Riewr Carpiac Artery (Figs. 258, 259, 1).—This originates from the front and to the right of the aorta, at the free margin of the sigmoid valves, and proceeds perpendicularly, or at a right angle, from the trunk, passing forwards to the right of the pulmonary artery, beneath the anterior auricle ; then to the right and backwards, to reach the auriculo-ventricular groove, which it follows till near the origin of the right ventricular furrow. Here it divides into two branches: one vertical, descending in this furrow to the apex of the heart, which it bends round to the front, and anastomoses with an analogous branch of the left coronary artery ; the other is horizontal, is smaller than the first, and follows the primitive course of the artery . (pense groove, also inosculating with the artery of the eft side. Lert Carprac Arrery (Fig. 258, 2).—This arises opposite the pre- ceding, at the same angle of incidence, passes behind the pulmonary artery, and divides, under the left or posterior auricle, into two branches similar in every respect to those of the right artery. The vertical branch descends in the left perpendicular furrow; the horizontal is lodged in the coronary groove ; and both anastomose with the analogous branches of the opposite vessel. From this arrangement, it results that the heart is surrounded by two arterial circles: a vertical, or ventricular, which has been compared to a meridian; and a horizontal, or auriculo-ventricular, analogous to an equatorial circle. In their course, which is more or less tortuous, the coronary arteries throw out a considerable number of ramuscules, which enter the muscular tissue of the heart. The vertical circle gives off branches which are entirely ventricular ; while from the horizontal circle come the superior or auricular, and inferior or ventricular branches. Among the latter there is one which, rising from the right artery where it bends at an angle beneath the auricle, enters the substance of the right ventricle by passing round the onary infundibulum; its ramifications anastomose with those of a similar branch from the left artery, and in this way establish another com- munication between the two vessels. Arricie II.—Posrrrion Aorva. Course—This artery is a continuation of the aortic trunk, which it nearly equals in volume, and from which it passes upwards and backwards, describing a curve whose convexity is antero-superior, and which is known as the arch of the aorta, It thus reaches the left side of the inferior face of the spine, about the seventh dorsal vertebra, behind the posterior extremity of the longus colli muscle, and is then carried directly backwards, following 524 THE ARTERIES. the vertebral bodies, though a little to the left at first ; it grad inclines to the right, however, and reaches the median plane at the pi of the diaphragm, Here it passes through the opening circumscribed by these two pillars, enters the abdominal cavity, and extends to the entrance of the pelvis, under the spine, still preserving its median position. On reachi the last intervertebral articulation, the posterior aorta terminates. ya double bifurcation, from which arises the external and internal iliac arteries. Relations.—To facilitate the study of its connections, the posterior aorta may be divided into two sections : one thoracic, the other abdominal. a, At its origin or arch, the thoracic aorta is crossed to the right by the trachea and cesophagus ; on the opposite side, it responds to the pulmonary artery and the left lung. For the remainder of its extent, it is comprised between the two layers of the posterior mediastinum, and through these is in relation with the pulmonary lobes, which are fissured for its reception ; this fissure is much deeper in the left than the right lung. Above, it is in contact with the bodies of the last twelve dorsal vertebre, and is accompanied on the right by the large vena azygos and the thoracic duct; the latter is often carried to the left for the whole or a portion of its extent. — (Remak observed muscular fibres on the external face of the aortic arch and thoracic aorta in the Horse, Sheep, and Pig ; the fasciculi they form are so large as to be visible to the naked oye) b. The abdominal aorta, enlaced by the abdominal nerves of the great sympathetic, corresponds, above, with the bodies of the lumbar vertebra, the originating tendon of the diaphragmatic pillars, Pecquet’s reservoir, and the common inferior vertebral ligament ; it passes above the pancreas and the peritoneum, the latter by its sublumbar layer covering the posterior two-thirds of the vessel. On the right, it is accompanied by the posterior vena caya, which perhaps it slightly pushes to the left of the median plane. Collateral branches.—The arteries emanating from the posterior aorta during its long course, very naturally form two classes; some are desig- nated parietal, because they are distributed to the parietes of the splanchnic cavities; the others are the visceral branches, destined for the organs lodged in these cavities. Among the parietal branches, may be noticed : 1. The intercostal arteries, furnished by the thoracic aorta. 2. The diaghragmatic arteries, whose origin is placed on the limits of the two portions of the vessel. 3. The lumbar arteries, and the middle sacral artery, springing from the abdominal aorta. The visceral branches are : 1, The broncho-cesophageal trunk, emitted by the thoracic portion of the aorta. 2. The celiac trunk, great mesenteric artery, small mesenteric artery, renal arteries, spermatic arteries, and small testicular or uterine arteries, which emerge from the abdominal portion. Preparation of the posterior aorta and its collateral branches.—Immediately after injecting according to one of the modes recommended at p. 519, place the subject in — the first position, the two posterior members being well extended backwards. Me the abdominal cavity, and remove from it the intestines in the manner already indicated. The tallow having become perfectly solidified during these necessary manipulations, dissection may be proceeded with at once, It is requisite, however, to remove the right and left walls of the thoracic cavity beforehand, by sawing through the last fourteen or fifteen ribs at six or seven inches from their superior extremity, and afterwards sepa- rating them from the sternum by the saw, taking the precaution of detaching the peri- be THE POSTERIOR AORTA. 525 ee insertion of the diaphragm. It is recommended to prepare, from before to behind, various visceral branches of the vessel; first, the broncho-cesophageal trunk, then the celiac trunk, next, the great mesenteric artery and the renal arteries, after spreading 3 out the intestinal mass as in figure 271; and. lastly, the small mesenteric and testicular ‘ arteries, after arranging the intestines as in figure 272. PARIETAL BRANCHES OF THE POSTERIOR AORTA, 1. Intercostal Arteries. (Fig. 237.) The intercostal arteries, placed, as their name indicates, in the intervals of the ribs, number seventeen pairs. Origin, Course, and Distribution.—The last thirteen emanate from the thoracic aorta only; the first comes from the cervical artery; and the next three are furnished by a special branch of the dorsal artery. The aortic intercostals escape at a right angle from the superior plane of the trunk, on a level with the bodies of the dorsal vertebre, and at regular intervals. Their origin is nearer that of the arteries on the opposite side as they are more anterior, the first two or three arising in pairs from a common trunk. These aortic intercostals ascend to the vertebral bodies, beneath the pleura, in crossing the direction of the sympathetic nervous chain and (the arteries of the right side only), in addition, that of the vena azygos and the thoracic duct, to the superior extremity of the intercostal spaces, where those of both sides divide into two branches: the one inferior, or proper intercostal ; the other superior, or dorso-spinal. The inferior and superior branches of the ‘first four intercostal arteries emanate solely from the trunk which furnishes them, and which is the superior cervical artery for the first intercostal, and the subcostal branch of the dorsal artery for the succeeding three. Inferior or intercostal branch.—This branch, the most considerable of the two, placed at first beneath the pleura, then between the two intercostal muscles, is lodged, along with a satellite vein and nerve, in the furrow on the posterior face of the rib, and descends to the inferior extremity of the intercostal space, where it terminates in the following manner: the first twelve or thirteen branches anastomose with the intercostal ramifications of the internal thoracic artery and its asternal branch; the others are prolonged into the abdominal muscles, where their divisions communicate with those of the anterior and posterior abdominal arteries, as well as with the circumflex iliac. In their course, these intercostal branches give arterioles to the pleura, the ribs, and the thoracic muscles, with the perforating ramuscules which cross these muscles to ramify in the skin and the panniculus carnosus, but on” of course, are absent where the pectoral wall is covered by the thoracic imb. Superior or dorso-spinal branch.—This passes directly upwards to be distributed to the spinal muscles of the dorsal region and the integument covering them, after giving off, when passing the intervertebral foramen, a branch which enters the spinal canal by that opening, and is destined for the — cord and its envelopes. An auxiliary of the middle spinal artery, is branch will be studied at greater length when the cerebro-spinal artery comes to be described. Variations in origin—Not unfrequently the first two pairs of aortic intercostal arteries proceed from a single trunk, which thus gives rise to four branches; and this trunk is also often the common source of these four 526 THE ARTERIES. intercostals and the bronchial and cesophageal arteries, when its volume is 4 very considerable. It is much smaller when it only gives off the second pair of intercostals, which is sometimes the case. 2. Lumbar Arteries. These are five or six in number, and do not differ in their gen arrangement from the intercostal arteries; they having the same mode of origin, the same division into two branches, and the same distribution. The superior, or lumbo-spinal branch, is much larger than the inferior, and goes to the muscles and integuments of the lumbar region; it also furnishes a branch to the spinal cord. The inferior branch passes above the large and small psoas muscles, giving them numerous twigs, and extending to the muscular portions of the transverse and small oblique abdominal muscles, where their ramifications anastomose with those of the cireumflex iliac artery. The last, and sometimes also the second-last lumbar artery, arises from the internal iliac trunk; the others emerge directly from the abdominal aorta, ~ 3. Diaphragmatic (or Phrenic) Arteries. These are two or three small vessels which spring from the aorta as it passes between the two pillars of the diaphragm, and are destined for that muscle. The left pillar receives a very insignificant branch ; but the right has two, the most considerable of which is alone constant ; it sometimes sends subpleural ramuscules to the right lung. 4, Middle Sacral (Sacra Media) Artery. This vessel is often absent, and when it exists is very variable in size, though always extremely slender. It arises from the terminal extremity of the aorta, in the re-entering angle comprised between the two internal iliac arteries, and is carried to the inferior face of the sacrum, where it is expended in lateral ramifications which go to the periosteum. It has been thought necessary to notice this artery, as it attains a considerable volume in Man and some animals, and continues the aortic tree beneath the sacral portion of the vertebral column. VISCERAL BRANCHES OF THE POSTERIOR AORTA. 1. Broncho-cesophageal Trunk. Destined for the lung, the visceral pleura, the mediastinum, and the esophagus, this artery arises, not, as is generally said, in the concavity of the arch of the aorta, but opposite to it, and very near, but to the right of, the first pair of intercostals; often even in common with these arteries and with the second pair... After leaving the aorta, it insinuates itself between that trunk and the csophagus, and above the bifurcation of the trachea divides into branches, the bronchial arteries. In its short course, it gives off the two wsophageal arteries and a certain number of innominate ramuscules. Bronomau Arreries.—The disposition of these two vessels is extremely __ simple; they enter the lung with the bronchi, one to the right, the other to the left, and there break up into arborescent ramifications which follow the air-tubes to the pulmonary lobules. (EsornaceaL Anrrertes.—These two arteries are placed in the posterior 1 See Intercostals. THE POSTERIOR AORTA, 527 mediastinum, one above, the other below the esophagus, which they accompany for a short distance, from before to behind, to the extremity of that canal. The superior esophageal artery, much more voluminous than the inferior, inosculates with a branch of the gastric artery. In its course it gives descend- ing branches to the cesophagus, and ascending ones to the mediastinum. The inferior esophageal artery also anastomoses with a branch of the gastric; most frequently with that noticed above. It likewise furnishes ascending and descending divisions; the latter, however, going to the mediastinum, and the former to the cesophagus. Innominate Ramuscutes.—The innominate ramuscules of the broncho- esophageal trunk do not all come directly from it; there being always ‘a certain number which emerge from the bronchial or cesophageal arteries. They are more particularly, distributed to the trachea, to that portion of the esophagus which is in contact with the posterior extremity of this cartilaginous tube, to the bronchial glands, the mediastinum, and the pulmonary pleura. Those destined for the latter form on the surface of the lung, along with the divisions of the pleural branch furnished by the gastric artery, a beautiful plexus. 2. Celiac Artery or Trunk (or Azis). This artery arises at a right angle from the inferior face of the aorta, immediately on the entrance of that vessel into the abdominal cavity. After a course of from half to three-fourths of an inch at most, in the middle of the solar plexus, and beneath the superior face of the pancreas, this trunk separates into three branches: a middle, the gastric artery; a right, the hepatic artery ; and a left, the splenic artery. 1. Gasrrio Artery (the coronaria ventriculi of Man.)—This artery descends on the large tuberosity of the stomach, extends to near the insertion of the cesophagus, and then divides into two branches: the anterior gastric. The first passes behind and to the right of the ok ema ll d crossing the small curvature of the stomach, gains the anterior face of that viscus, where it separates into flexuous and divergent ‘branches which run beneath the serous membrane, and are carried more particularly towards the left cul-de-sac and around the cardia. The second vessel is distributed in the same manner to the posterior wall of the organ, but chiefly to the right sac. Independently of these two arteries, the gastric trunk gives off a third and constant branch, which often comes from one of the two branches of this trunk, and sometimes also from the coeliac artery itself, or from the splenic. This branch accompanies the cesophagus, along with the right pneumogastric, crosses the opening of the right pillar of the diaphragm to enter the pectoral cavity, and then divides into two branches, each of which anastomoses with one of the cesophageal arteries, and is then thrown over the posterior extremity of a pulmonary lobe, which it covers with a magnifi- cent subpleural reticular arborisation. This gastro-pulmonary artery often anastomoses with the superior cesophageal branch only, and goes exclusively to the right lung; for the left:lung and the inferior et artery, in this case there is a special branch which emanates from anterior It is not rare to meet with varieties of another kind, but of which itis not necessary to speak ; inasmuch as in these pleural ramifications we find a disposition common to the whole arterial system: distribution almost invariable, origin very inconstant. 2. Spientc Anrery.—The largest of the three branches of the ceeliac 528 THE ARTERIES, ~ axis, this artery is directed downwards and to tho left, lying beside its ale satellite vein and the superior face of the left extremity of the pancreas. It reaches the anterior fissure of the spleen in turning round the large tube- rosity of the stomach, passes along the entire length of that fissure, and leaving it only near the point of the organ to throw itself into the great omentum, where it is named the left gastro-omental artery (or gastro-epiploica sinistra), The splenic artery gives off, during its course, very numerous collateral branches. These are: | 1. External or splenic ramifications, which immediately enter the substance of the spleen. =e 2. Internal or gastric ramifications, also called the short vessels (vasa brevia) in Man, which are comprised between the two layers of the gastro- splenic omentum, and go to the great curvature of the stomach, where they nearly always divide into two branches: one which ramifies on the anterior wall of the viscus, the other on its posterior wall. These vessels inoseulate with those sent to the membranes of the stomach by the proper gastric artery. 3. Posterior or omental twigs of little importance, destined for the great omentum. Carus Left gastro-omental artery.—This artery follows the great curvature of the stomach to a distance varying with the state of repletion of that viscus, passing between the two layers of the omentum, and inosculating with the right gastro-omental artery. The branches it sends off on its track are descending or omental, and ascending or gastric ; the latter bei disposed exactly like the analogous branches emanating directly from the splenic artery. , 3. Hepatic Anrery.—Applied to the superior face of the pancreas, and incrusted, as it were, in the tissue of that gland, whose anterior border it follows, the hepatic artery is directed from left to right, passes under the posterior vena cava, which it crosses obliquely, reaches the posterior fissure of the liver, and enters it with the vena porte to become broken up into several branches, whose ultimate divisions carry nutritive blood to the lobules of the liver. Before reaching that organ, however, the hepatic artery furnishes the pancreatic branches, the pyloric artery, and the right gastro-omental artery. Pancreatic arteries.—Irregular and very numerous, these branches are detached from the hepatic artery on its passage over the superior face of the pancreas, and plunge into the tissue of that gland, whose arterial blood is chiefly derived from this source. Pyloric artery.—This vessel arises at the dilatation towards the origin of the duodenum, before the hepatic artery enters the posterior fissure of the liver, and most frequently by a trunk common to it and the right gastro-omental artery. It passes towards the small curvature of the stomach, and sends off branches around the pylorus, which anastomose with the posterior gastric arteries and the right gastro-omental artery. Right gastro-omental artery (gastro-epiploica deatra).—This artery crosses the duodenal dilatation inferiorly and posteriorly, to place itself in the substance of the great omentum; in doing which it passes along the great curvature of the stomach, and anastomoses by inosculation with the left gastro-omental artery. In its course, it throws off omental and gastric branches, which are analogous to those emanating from the latter vessel. Before crossing the duodenum, it also emits a particular branch, designated in treatises on Veterinary Anatomy tle duodenal artery; this is a somewhat considerable division, which follows the small curvature of the duodenum in THE POSTERIOR AORTA. 529 _ the substance of the mesentery, and joins the first artery belong’ ng to the left - fasciculus of the great mesenteric, after furnishing some twigs to the and numerous branches to the duodenum. In terminating the description of the right gastro-omental artery, it may be remarked that the stomach, owing to the anastomoses uniting that vessel with the artery of the left side, is suspended, as it were, in a vertical arterial circle, formed by the splenic and left gastro-omental arteries on the one part, and the hepatic and right gastro-omental arteries on the other—a circle whose concavity sends out on the stomach a great number of divisions, which communicate with the arterial ramuscules proper to that viscus. 3. Great Mesenteric Artery. (Fig. 271.) Tle great mesenteric artery, which almost entirely supplies the intestinal mass with blood, is as remarkable for its volume as for its complicated distribution. This complexity, together with that of the intestine itself, gives rise to some difficulty in the study of this vessel; but this may be averted by adopting the mode of description, as simple as it is methodical, resorted to in his lectures by M. Lecoq. The great mesenteric arises at a right angle from the abdominal aorta, at the renal arteries, and at 2 or 24 inches behind the cceliac trunk, from which it is separated by the pancreas ; it is directed immediately downwards, enlaced by the anastomosing nervous branches of the solar plexus, and divides, after a course of from 1 to 14? inches, into three fasciculi of branches, which are distinguished as left, right, and anterior. The left fasciculus goes to the small intestine ; the right is distributed to the terminal portion of that intes- tine, to the cecum, and to the first portion of the loop or flexure formed by the large colon; the anterior is carried to the second portion of that flexure, and to the origin of the small colon, The order in which these three fasci- culi have been indicated will also be that followed in their description ; it has, as will be observed, the advantage of recalling to the memory the succession of the various parts of the intestine, and consequently the passage of the food in this important portion of the digestive canal. A. Anreries or THE Lert Fascicutus (Fig. 271, 2).—These arteries number from fifteen to twenty,and are named the ARTERIES OF THE SMALL INTESTINE (vasa intestini tenuis), because of their destination. All spring at once from the great mesenteric artery, either separately,or several in common, and pass between the two layers of the mesentery to gain the intestine. Before reaching the small curvature of that viscus, each divides into two branches, which go to meet corresponding branches from the neighbouring arteries, and to anastomose with them by inosculation ; from this arrangement results a series of uninterrupted arterial arches, whose convexity is downwards, and which exist for the whole length of the intestine opposite, and in proximity to, its concavity. From the convexity of these arches emanate a multitude of branches that arrive at the inner curvature of the intestine, and whose divisions pass to each of the faces of that viscus to rejoin and anastomose on its great curvature. These divisions are situated be- neath the peritoneum or in the muscular layer, and send the majority of their ramuscules to the mucous tunic, which is therefore distinguished by its great vascularity : a featurecommon to all the hollow organs in the abdominal cavity. * This trunk of the great mesenteric is usual}y, in the old horses killed for dissec- tion, the seat of a more or less voluminous aneurism, which sometimes extends to the ial tube placed at the origin of the branches of the right fasciculus, and it is not unfrequently met with in oneor the other section of the great mesenteric ee M 480 THE ARTERIES. Fig. 271. A - : 1, Abdominal aorta; 2, 2, ; aI 2, Arteries of the left fas- Pon ciculus, destined for the a small intestine; 3, Teo- —" cecal artery ; 4, Superior “+ cecal artery; 5, Inferior cecal artery; 6, Artery 7 i of the arch of the cecum ; i 7, Right colic artery; 8, ! Left colic artery ; 9, First 3 artery of the small colon. 4 DISTRIBUTION OF THE GREAT MESENTERIC ARTERY. , ‘ ‘ ; ae ee —- } = ms _ A —— ee —_— or ee ———- - ideal Die ana oo : THE POSTERIOR AORTA, 531 Such is the general arrangement of the arteries of the small intestine ; and it remains to indicate some of their special characters, which are as follows : 1, The longest arteries of the small intestine are the most posterior, as they follow the development of the mesentery, by which they are sus- tained; 2, The anterior arteries generally form two series of superposed arches, before sending their divisions to the intestine; 3, The first reaches the duodenum and anastomoses with the duodenal artery—a branch given off the ceeliac axis ; 4, The last communicates with the ileo-crecal artery—one the branches of the right fasciculus. B. Arrerres or THe Ricur Fascroutvs.—The right fasciculus of the mesenteric artery constitutes, at first, a single trunk some inches in ength, which soon divides into four branches; these are as follows: the ileo-cecal artery, the two cecal arteries, and the right or direct colic artery. Inx0-Cmoan Arrery (Fig. 271, 3)—This vessel often has its origin from the internal cecal artery. It is placed between the two layers df the mesentery, follows for a short distance, and in a retrogade manner, the ileo- ewcal portion of the small intestine, and wholly anastomoses with the last - artery of the left fasciculus, after emitting a series of branches, which are distributed to the intestinal membranes. Cacat Arrertes.—Distinguished into internal or superior, and external or inferior, these two arteries pass downward and a little to the right, towards the concavity of the cecal flexure, embracing between them the terminal extremity of the small intestine, and lying at the middle part of the cxcal sac, whose direction they follow. The superior, or internal cecal artery, is lodged in the most anterior of the fissures formed by the longitudinal bands of the cecum, and extends beneath the serous tunic to nearly the point of the viscus, where it terminates by anastomosing with the external cwcal artery. The branches furnished by this artery during its course escape in a perpendicular direction, and distribute their ramifications on the walls of the cecum (Fig. 271, 4). The external, or inferior cecal artery, passes between the cecum and the igin of the colon, to descend along the first-named receptable by placing itself in one of the external fissures, which is situated outwardly and posteriorly. Arriving at the point of the organ, this artery bends over it to anastomose with the vessel just described (Fig. 271,7). It gives off on its track a series of transverse ramifications, similar to those of the latter artery ; and besides these, a remarkable branch which may be named the artery of the cecal arch. This branch is detached from the ere vessel near the origin of the colon, and ascends to the cwcal arch, whose concavity it follows outwardly to pass forwards and downwards to the initial portion of the large colon, where it disappears after following a certain course. The numerous collateral branches detached by this artery are sent to the walls of the latter portion of intestine, and the arch of the cwcum (Fig. 271, 6). Rieut or Dreecr Corio Anrery (Fig. 271, 7).—This is the largest of the branches composing the right fasciculus of the great mesenteric artery. Destined for the right portion of the flexure formed by the large colon, it lies immediately beside that viscus, beneath the peritoneal membrane, following it from its origin to its pelvic curvature, where the artery anastomoses by inosculation with the left colic or retrograde artery. C. Anrerrms or tas Anrerror Fasciou.vus.—These are only two in number: the left colic or retrograde, and the first artery of the small colon, ° joined at their origin to an extremely short trunk. Lerr Conic on Rerrogrape Artery (Fig. 271, ae se eae. M 532 THE ARTERIES. to the left portion of the colic flexure, which it passes over, beneath the peritoneum, from the terminal extremity of the viscus to the pelvic curvature, where it meets the right artery; in this manner it follows a course the inverse of that pursued by the aliment, and whence its name of retrograde colic artery. . ; Considered collectively, the two colic arteries represent a loop or flexure exactly like that formed by the large colon itself. They proceed parallel to each other, and finish, after being slightly separated, by uniting to form a parabolic curve. This arterial loop occupies a deep position on the intestinal loop, being found on the inferior face of the first and fourth sections of the large colon, in the concavity of the flexure which gives rise to the suprasternal and diaphragmatic curvatures, and on the superior plane of the second and third portions of the viscus. A considerable number of collateral branches escape perpendicularly from this arterial loop, and pass into the membranes of the intestine; some of them establish a transverse communication between the two vessels. First Arrery or THe Smart Conon (Figs. 271, 9; 272, 4).—This branch, whose calibre is often considerable, is inflected to the left, downwards and backwards, to be placed in the substance of the colie mesentery, very near the lesser curvature of the floating or small colon. It soon meets a branch of the small mesenteric artery, with which it anasto- moses by inosculation. D. Innommyate Brancues oF THE Great Mersentery.—These are the twigs sent to the lymphatic glands, supra-renal capsules, mesentery, and pancreas, and whose existence it is sufficient merely to mention. Among those supplied to the pancreas, there is one of somewhat considerable volume. E. Tse Awnastomoses or THE Great Mesenteric Artery.—The multiplicity and calibre of these anastomoses assure, in the most favourable manner, the circulation of the blood in the intestinal mass, which, by reason of its great mobility, is exposed to displacements capable of inducing more or less extensive compression. Not only do these anastomoses unite the different branches destined to the same portion of the viscera, be it the small intestine, the cecum, or the large colon; but they also establish communica- tions between the great mesenteric artery and the neighbouring trunks, which in case of need can maintain the circulation: as, for example, when the two intestinal arteries are completely obstructed. The blood from the coeliac trunk can really pass from the duodenal artery into the branches of the left fasciculus of the great mesenteric artery; then by the ileo-cecal artery into the branches of the right fasciculus, and thence into the left colic artery, which, finally, transmits it to the first artery of the small colon, as well as to the arches of the small mesenteric artery. The communica- tion existing between the broncho-cesophageal and the ceeliac trunks, through the medium of the cesophageal and gastric arteries, even allows a collateral circulation to be formed, and which would be capable of supplementing the posterior aorta, supposing that vessel tied behind the trunk that distributes blood to the bronchi and cesophagus. 4. Small Mesenteric Artery. (Fig. 272.) This artery carries blood to the small colon and rectum, and arises at a right angle from the inferior face of the abdominal artery, from 44 to 6 inches behind the great mesenteric. It descends between the two layers of the colic mesentery, and is soon inflected back in describing a curve ‘ THE POSTERIOR AORTA, 533 upwards, to pass above the rectum; when near the anus, its terminal divisions enter the walls of that intestine. In its course this artery gives off, at pretty regular intervals, thirteen or fourteen branches, the foremost of which are the largest and longest; they originate from the convexity of the artery—that is from below, and either Fig. 272. DISTRIBUTION OF THE SMALL MESENTERIC ARTERY; THE SMALL COLON WITH Irs MESENTERY IS SPREAD OUT, AND THE SMALL INTESTINE THROWN BACK TO THE RIGHT UNDER THE LARGE COLON, 1, Trunk of the small mesenteric artery; 2, Great mesenteric artery; 3, Its anterior fasciculus; 4, First artery of the small colon, forming part of that fasciculus ; 5, Retrograde colic artery ; 6, Right fasciculus of the great mesen- teric; 7, Branches of the left fasciculus; 8, Renal artery ; 9, Terminal extremity of the aorta; 10, External iliac artery ; 11, Circumflex iliac artery; 12, Internal iliac artery. singly or in clusters; the latter disposition is the most common for the first four or five. They descend into the mesentery and arrive near the superior curvature of the intestine, where they are disposed in the following manner: The first seven or eight bifurcate, and form arches like those of the arteries supplying the small intestine, differing from them only in being nearer the 534 THE ARTERIES. small curvature of the colon; the other branches, which are destined for the terminal part of that viscus and the rectum, ramify in the intestinal membranes without having previously formed any arches. The anterior ramuscule of the first branch anastomoses directly with the artery sent to the small colon by the great mesenteric, and from this anastomosis results the first colic arterial arch. 5. Renal or Emulgent Arteries. (Fig. 275, 2.) These are two arteries, one for each kidney, detached laterally, and at a right angle, from the abdominal aorta, near the great mesenteric artery ; passing outwards to the internal border of these organs, each divides into several branches, which enter the gland either by its notch: or by its inferior face. Reaching the interior of the kidney, these branches subdivide, and form a network of large vessels placed on the limit between the cortical and medullary substances, from which a multitude of ramuscules are given off, and pass almost exclusively into the tissue of the cortical portion, (See the description of the kidneys.) The right renal artery, longer than the left, passes between the small — psoas muscle and the posterior vena caya, to reach the right kidney. Both arteries are in relation with the posterior extremity of the supra-renal capsules. ; Remarkable for their relatively enormous volume, when compared with that of the glands receiving them, these arteries do not, before penetrating the proper tissue of the kidneys, give off any but a few unimportant ramuscules, the principal of which proceed to the supra-renal capsules (Fig. 275). Other twigs from the great mesenteric artery, or even from the aorta itself, also supply these small bodies. It is not unusual to find the kidneys receiving vessels from the arteries in their vicinity. Thus, we have seen an artery from the external iliac pass into a kidney by its lower face ; and we have also observed an artery, detached from the aorta along with the great mesenteric, enter the kidney by its anterior border. 6. Spermatic Arteries. ‘hese arteries differ in the male and female; in the male they are also named the great testicular arteries ; in the female they are exclusively designated as the utero-ovarian arteries. Great Tersticunar Artery (Fig. 275, 3).—This arises close to the small mesenteric artery, either before, behind, or to one side of it, but rarely on the same level as the artery of the opposite side; it is then directed backwards and downwards, sustained, with its satellite vein, in a particular fold of peritoneum, and reaches the entrance to the vaginal sheath (internal abdominal ring), into which it is seen to pass with the other constituent portions of the spermatic cord, and to descend on the testicle by forming remarkable flexuosities united in an elongated mass. Arrived within the head of the epididymis, this artery insinuates itself under the tunica albuginea, becomes incrusted, as it were, in its substance, and successively passes round the superior border, posterior extremity, and the inferior border and anterior extremity of the testicle. In this course it is very sinuous, and detaches at a right angle a large number of equally flexuous branches, which creep over the faces of the ergan while sending numerous ramuscules into its structure. The epididymis also receives its blood by this artery. THE POSTERIOR AORTA, 535. - Urero-ovanran Artery.—The origin of this vessel is conformable with at of the preceding artery. It is placed between the two laminw of the ad ligament, and soon bifurcates into the ovarian ‘and uterine arteries. The ovarian branch describes numerous flexuosities, like the corresponding artery in the male, and comports itself on the ovary in the same manner as the latter vessel does on the testicule. The uterine branch passes to the cornu of the uterus, where its divisions anastomose with the proper uterine artery. 7. Small Testicular Arteries: Male. Uterine Arteries : Female. Sumani Testicutar Artery (Cremasterico Artery, ARTERY OF THE Corp).—A pair, like the great testicular artery, this vessel is very slender, and originates either from the aorta between the internal and external iliaes; or from the latter, near- its commencement. The last being the most ‘common, it is usual to describe it asa collateral branch of the crural (external iliac) trunk. We have regarded it as an artery emanating directly from the posterior aorta, in order to include its description with that of the great testicular and the utero-ovarian arteries. Whatever may be its mode of origin, it gains the entrance to the vaginal sheath, and enters it with the spermatic vessels, to be distributed to the yarious parts constituting the cord. Before penetrating the substance of this cord, it gives off several ramuscules destined for the peritoneum, iliac glands, ureter, and deferent canal. Urerme Artery.—This has the same point of origin as the preceding, its analogue, but differs from it in its larger volume. It is placed between the two layers of the lumbar ligament, and is divided into two branches on arriving at the small curvature of the uterine cornu: the anterior branch anastomoses. by its divisions with the utero-ovarian artery; the posterior. passes to the body of the matrix, where it communicates with the vaginal artery. DIFFERENTIAL CHARACTERS OF THE POSTERIOR AORTA AND ITS COLLATERAL BRANCHES IN OTHER THAN SOLIPED ANIMALS. 1. Posterior Aorta in Ruminants. The artery pursues the same course as in Solipeds, and also terminates by four branches, tow the entrance to the pelvic cavity. Parrerat Braxcurs.—The intercostal arteries only differ from those of the Horse in their number; as but twelve are met with, of which eight or nine alone are furnished by the Do gaa! aorta. : lumbar and diaphragmatic branches are ubsolutely identical, in their disposition, with the analogous arteries of Solipeds. The middle sacral ar is more considerable in volume, particularly in the Sheep and Goat. ‘This will be referred to hereafter (see infernal iliae artery of Ruminants). Viscerat Brancues.— Broncho-esophageal trunk.—This offers nothing particular, Celiac trunk (Fig. 273, 1).—This artery descends on the rumen, a little behind the insertion of the cesophagus, is directed to the right, and divides near the omasum into two terminal branches—the superior and inferior arteries of the omasum and abomasum. The collateral branches escaping from this trunk are: 1. Several diaphragmatic arteries. 2. The splenic artery, almost exclusively destined for the spleen (Fig. 273, 8). 8. The superior artery of the rumen, always wising from a very short trank common to it and the preceding vessel, is carried backward to the superior face of the rumen, and from this descends between the two conical vesicw to anastomose with the artery of the inferior face of the viscus (Fig. 273, 2). 4. The inferior artery of the rumen, which is insinualed between the two anterior and afterwards runs along the inferior face of the organ, passing towards the notch separating the two conical vesicw, to meet the superior vessel ( Fig. 278, 3). 536. | THE ARTERTES, 5. The artery of the reticulum, having usually a common origin with the i of the rumen, and passing forward on the left of the csop to be near the insertion of that conduit, into two branches: one, the superior, right to the small curvature of the viseus (Fig. 273, 5); the other, the ibid nn the fissure separating the great curvature of the reticulum from the right ben paunch, and giving to the latter organ a great number of branches (Fig. 273, 4). 6. The hepatic artery, which is not only distributed to the liver, but also furnishes : brsinch for the gall- “bladder, and a duo!tenal artery breaking up into two branches: posterior branch forming with the first artery of the small intestine an arching annston mosis ; the anterior communicating with the superior artery of the omasum and abomasum. This hepatic artery always originates between the trunk common to the sokeene rte and the superior branch of the rumen, and that which gives rise to the superior of the same viscus and the artery of the reticulum. The terminal branches of the cceliac artery comport themselves as follows : 1. The superior a of the omasum and abomasum passes successively to the great curvature of the first of these reservoirs, and to the concave curvature of the second ; it goes beyond the pylorus to unite with the duodenal branch of the hepatic artery ie = inosculation (Fig. 273, 6). cal a Fig. 273. ARTERIES OF THE STOMACH IN RUMINANTS. 1, Celiac trunk; 2, Superior artery of the rumen; 3, Inferior artery of the rumen; 4, Inferior artery of the reticulum; 5, Superior artery of the reticulum ; 6, Superior artery of the omasum and abomasum ; 7, Inferior wt of ditto; 8, Splenic artery; A, sophagus ; B, Left sac of the rumen; B’, Left conical vesica; C, Right sac of the rumen; c’, Right conical vesica ; D, Reticulum ; E, Omasum ; ¥, Abomasum ; G, Duodenum ; R, Spleen. 2. The inferior artery of the omasum’and abomasum, on the contrary, passes at first over the small curvature of the omasum, afterwards the great curvature of the abo: and disappears in the omentum, to which on its course it furnishes a great number branches (Fig. 273, 7) <-_ In small Seemtneata the rage spree Sol the arteries of the coeliac trunk presents some modifications. We will cite the prin which belong to the mode of ori n of the two branches destined for the serve um: these branches form two vessels which arise singly from the coeliac trunk ; the inferior artery at the same point as — the superior artery of the rumen, the superior towards the terminal bifurcation of the trunk. Great mesenteric artery.—Its origin ap; Vie very closely that of the cceliac trunk, After a course of from 6 to 8 inches, it divides into two branches—an anterior and a > THE, POSTERIOR AORTA. 537 rior. The first, destined for the small intestine, creeps above it, between the two 's of the mesentery, and passes backward by describing a curve which gives off from pavexity—that i is, below, a great number of branches, analogous in their mode of rmination to the arteries of the small intestine in the Horse. The posterior branch goes bo plarge intestine, where it separates into two principal branches: one which passes e colon, and whose divisions weg’ to the right, from before to behind and from aboye , the conyolutions described by that viseus; another which reaches the concave < curvature of the excum, and anastomoses by an arch with the terminal extremity of the _ parent-branch of the arteries supplying the small intestine. Rank mesenteric artery.— Very short and narrow. een germadic, and small testicular arteries.—These do not differ in their essential 4 - Alapaston the analogous vessels in Solipeds. 2. Posterior Aorta in the Pig. _ With the exception of the mesenteric vessels, whose distribution resembles that already indicated for Ruminants, and with the exception, also, of the middle sacral artery, which will be alluded to when describing the ivternal iliac arteries, all the branches given off by the posterior aorta comport themselves almost as in the Horse. ; 3. Posterior Aorta in Carnivora. In these animals, as well as in the Pig, the denomination of posterior aorta is not justifiable, because the arteries of the head and thoracic limbs spring directly from the aortic arch. The branches of the aorta are distinguished as parietal and visceral. A. Parrerat Branounes.—Beyond the fourth space, the intercostal arteries are fur- _ nished by the aorta; the first is a cee and throws off some considerable filaments he muscles of the withers. The first two lumbar arteries arise from the thoracic Bice of the aorta, because of the very backward insertion of the diaphragm ; the third detached between the two pillars of that partition. In the abdominal cavity, close to { the great mesenteric, the aorta gives off a branch that soon divides into two: one is = and descends on the posterior face of that muscle ; the other reaches the region, passes over the psoas muscle, and traverses the abdominal wall in the “spe £ Remade the | transyerse processes of the lumbar yertebre. We will speak presently of c B. eee. ‘Brancues.—I have not found in the Dog any special bronchial arteries ; but there are four or five esophageal arteries that arise from different points of the thoracie aorta; they descend into the mediastinum, to the right and left of the J cesophagus, to which they are distributed. They furnish branches that accompany the ____ bronchi and enter the lungs. The celiac trunk is again divided into three branches, whose disposition is as follows: The gastric, or stomachic coronary artery, does not divide into two branches (auterior and pac gastric) as in Solipeds.” Near its origin it furnishes a pancreatic branch; then expends itself in a great number of filaments that are pron over the posterior face and great tuberosity of the stomach, or over its anterior after crossing the small curvature. ‘ The splenic artery reaches the spleen at the middle of its upper border. It gives on noel course: 1, A splenic branch that enters the upper extremity of that organ; 2, The ee err i The hepatic artery provides the principal hepatic vessel at the fissure of the liver; it is then continued b t gastro-omental artery. sl pggeromieae the latter gives origin to the pyloric and the pancreatico-duodenal the latter is voluminous, is lodged ‘in the substance of the pancreas, and onl ao its last filaments with the great mesenteric. ’ The great mesenteric a arises in the vicinity of the cosliac artery ; it forms a curve _ whose convexity is backward, and anastomoses by its extremity with the pancreatico- ? branch of the hepatic. From its convexity are detached several filaments soa hed to the small intestine), that form arches towards the smaller curvature of that viseus. Behind, and at a short distance from its ven, ab it gives a branch to the cecum _ and branches to the colon; the latter are sometimes The small mesenteric commences near the Sitenivaiion ‘of the aorta, and divides into two branches : one passing forward, and the other backward; they form the hemorrhoidal vessels (see Fig. 209). There is nothing special to note with regard to the renal and spermatic arteries. x | eS eS eS a ee ee a ae 538 THE ARTERIES. COMPARISON OF THE AORTA OF MAN WITH THAT OF ANIMALS, The aorta in Man offers the same general disposition as in the Carnivora, the trunk being inflected across, to be placed along the body of the dorsal and first leche: where it terminates in the iliac vessels. It furnishes the coronary arteries, the arteries of the head and thoracic members— which will be noticed hereafter ; and the parietal and visceral branches to the chest and abdomen. At first these are the intercostals, beyond the third space; the dia arteries, superior and inferior according as they occupy one or other face of the diaphragm ; and, lastly, the lumbar arteries. Among the visceral branches are di ished: 1, The bronchial arteries, two in number; the left arises from the concavity of the aortic arch, and enters the } with the left bronchus; the right originates alone or in common with the preceding, and enters on the right bronchus; 2, The esophageal arteries disposed somewhat as in the Dog; 8, The celiac trunk, whose distribution is nearly identical with that of the Carnivora ; 4, The superior or great mesenteric, disposed in arches as in the Dog (see Fig. 276, 9). Its last branches to the cecum, and the ascending and origin of the transverse portion of the colon; 5, The inferior or small mesenteric, which arises 14 to 2 inches from the bifur- cation of the aorta; this artery descends into the meso-colon, and terminates on the sides of the rectum by the hemorrhoidal vessels; to the left, they emit branches to the large intestine; the first ascend along the descending colon, and anastomose on the transverse colon with the right colic branch of the superior mesenteric; 6, The renal and b arteries, which do not offer important differences ; 7, Lastly, the spermatic arteries, which are remarkable for the length of their course, commencing, as they do, at the aorta, a short distance below the renal vessels. Arrioie III.—Internat In1ac Artertes on Petvic Trungs. (Fig. 277, 2.) The two internal iliac arteries represent the middle or internal branches of the quadrifurcation formed by the posterior aorta at its terminal extremity. Extending from the body of the last lumbar vertebre, to near the terminal insertion of the small psoas muscle, in an oblique direction downwards, outwards, and backwards, these arteries correspond: in front, with the trunks of the common iliac veins, which separate them from the external iliacs; inwards, to the peritoneum; above and outwards, to the sacro-iliac articulation and to the ilium. In its course, the internal iliac artery emits the following branches: the umbilical artery, artery of the bulb, ileo-lumbar, gluteal, and subsacral arteries. At its terminal extremity, it is divided into two branches which ride on the superior border of the tendon belonging to the small psoas muscle: the one within, the other without that tendon. The first is the obturator artery, the second the ileo-femoral artery. All these branches will be studied in the order of their enumeration. Preparation of the internal iliae artery—Plave the subject in the first a remove one of the posterior limbs, leaving the rectum and bladder in the pelvis, and slightly inflating the latter organ. Dissect, on the side from which the limb has been removed, the origin and visceral ramifications of the branches furnished by the trunk of the artery. Follow, on the opposite side, the ramifications given off by these branches to the muscles. To conveniently prepare the coccygeal arteries, it is necessary, after removing the great sciatic ligament and dissecting the internal artery of the bulb along with the subsacral trunk, to raise up the rectum and bladder by means of the chain-hooks. 1. Umbilical Artery. (Figs. 274, 5; 277, 8.) This artery forms a considerable vessel during fotal life, and carries the blood of the foetus to the placenta; it will be described in detail in the anatomy of the foetus. In the adult it is almost entirely obliterated, appearing only as a fibrous cord extending from the internal iliac artery to the fundus of the bladder, and placed at the free margin of the lateral serous fold detached from the THE INTERNAL ILIAC ARTERIES. 539 cul-de-sac of that organ. This cord throws off on its track, one or more | vesical branches, beyond which its canal altogether disappears. These Fig. 274. A, Left kidney; B, Right kid- ney; a, 6, Ureters; ©, ©, Supra-renal capsules; D, Bladder; EB, E, Testicles; é, Head of the epididymis ; e’, Tail of the epididymis ; F, Deferent canal; G, Pel- vic dilatation of the defe- rent canal; H, Left vesicula seminales; the right, with the deferent canal of the same side, has been removed, to show the insertion of the ureter into the bladder ; I, Prostate; J, Cowper’s glands; K, Membranous portion of the urethral canal; L, Bulbous portion of the same; M, Cavernous body of the penis; m, m, Its roots; N, Head of the penis,—1, Abdominal aorta; UPPER AND GENERAL VIEW OF THE GENTTO-URINARY 7; 2, Renal arteries giving APPARATUS AND ARTERIES IN THE MALE. off the principal capsular artery; 3, Spermatic, or great testicular artery ; 4, Common origin of the internal pudic and umbilical arteries ; 5, Umbilical artery ; 6, Its vesical branch; 7, Internal pudic artery; 8, Its vesico- é prostatic branch. 540 . THE ARTERIES. vesical branches also, though very rarely, come from the internal poten fe - % the bulb; in which case the obliteration of the umbilical artery is complete. _ 2. Internal Pudic Artery, or Artery of the Bulb. oy (Figs. 274, 7; 275, 16; 277, 4.) a This vessel differs in its distribution in the male and female. ql Internat Pupio Arrery in THE Mate.—It proceeds from the internal __ iliac, near the origin of that vessel, by a trunk common to it and the 4 umbilical artery ; it is then directed backwards, following the superior border = of the internal obturator (pyriformis) muscle, and placed either without or = within the texture of the great ischiatic ligament. Arrived at the neck of the : bladder, it enters the pelvic cavity, lying beside the prostate and Cowper's ; glands, and is finally inflected downwards, passing round the ischial arch to i reach the bulb of the urethra. | 7 In its progress it furnishes : 3 1. Insignificant ramuscules to the muscle adjoining the sacro-ischiatie ligament. as 2. The vesico-prostatic artery (Figs. 274, 8; 275, 17). This isa branch constant in its distribution, but variable in its origin. Destined to supply the prostate gland, vesicule seminales, the pelvic dilatation of the deferent canal and the canal itself, as well as the bladder, it usually commences near the prostate gland, and passes from behind to before, in a flexuous manner, on the vesicule seminales and the deferent canal. 3. Slender ramifications for the pelvic portion of the urethral canal, Cowper's glands, the anus, and the ischio-cavernous muscle (erector penis). The terminal extremity of the vessel is insinuated beneath the accel- erator muscle, and immediately divides into a multitude of ramuscules which enter the erectile tissue of the urethral bulb, where they comport themselves as in all tissues of this kind. Varieties.—It is not rare to see the artery of the bulb detach, before attaining Cowper's gland, the cavernous artery, which then passes round the ischial arch along with the nerve of the penis. Sometimes it only gives off the posterior dorsal artery of the penis, a branch of the cavernous. DisTr1eution oF THE INTERNAL Puprc Artery in THE Fematz. (Fig. 277, 4.)—This artery terminates, towards the vagina, by rectal, vulvular, vaginal, and bulbous branches; the latter are for the bulb of the vagina. As in the male, it does not give off more than one important branch on its course ; this, the vaginal artery (Fig. 277, 5) is analogous in every respect to the vesico-prostatic artery ; its terminal divisions go, not only to the middle portion of the vagina, but also to the body of the uterus, where they anastomose largely with the branches of the uterine artery, and even pass to the bladder and rectum. The internal pudic artery of the female, as in the male, is liable to nu- merous variations. It may furnish the cavernous artery, or only the dorsal artery of the clitoris. We have seen the vaginal artery come from the umbilical. 8. Subsacral or Lateral Sacral Artery. (Figs. 275, 2; 277, 6.) Rising within the internal iliac artery, at, or a little behind the lumbo- sacral articulation, lying above the peritoneum, and beneath the sacral foramina and the large nerves passing through them, this vessel is directed backwards and arrives near the posterior extremity of the sacrum, where THE INTERNAL ILIAC ARTERIES. dl it ends in two branches: the ischiatic and lateral coceygeal arteries, to which __- must be added the middle coccygeal artery, usually emitted by the subsacral | vessel of the right side. ContateraL Branones.—The lateral sacral artery distributes on its course several insignificant ramuscules destined for the neighbouring parts, and four spinal branches which enter the vertebral canal by the inferior sacral foramina, and leave it again by the superior, after throwing off some divisions to the posterior extremity of the spinal cord and the nerves of _ the tail; these branches ramify in the muscles lying on the sacral spine. Termmat Brancues.—1. Iscntatic Antery.—It crosses the ligament of the same name to place itself under the superior extremity of the anterior ion of the long vastus, passes backwards and downwards, and divides into several branches which descend into the substance of the ischio-tibial muscles (semimembranosis and semitendinosis), to beneath the ischial tuberosity. These branches anastomose, by their extremities, with the ascending branches from the the femoro-popliteal, as well as with the divisions of the obturator and deep femoral arteries. 2. Lareran Coccyerat Artery.—This vessel represents the continua- tion of the lateral sacral artery, though not by its volume, which is much less than the ischiatic artery, but in its direction. Jt proceeds from before to behind, for the whole length of the coccyx, between the rudimentary yertebre of that region and the depressor muscles of the tail, gradually diminishing in volume, and detaching on its course a series of collateral | ramuscules which are expended in the muscles and integuments of the tail. There has been described a superior lateral artery, a branch of the pre- ceding, and which passes between the elevator muscle of the tail and the superior face of the coccygeal vertebre ; but this artery never exists: the superior coccygeal muscle receives its blood by branches analogous to the spinal branches of the intercostal, lumbar, and sacral arteries, and which emanate from the lateral coccygeal artery at each of the vertebral bodies. 3. Mippte Coccyerat Artery.—The origin of this vessel is liable to numerous variations. Ordinarily, it is detached from the right subsacral artery, in common with the lateral coccygeal of the same side. At other times, it escapes from the lateral at 5 or 6 inches from its origin. In a specimen now before us, it arises nearly from the middle of the subsacral artery. And it may also proceed from either the left sacral or the corres- ponding lateral coccygeal artery. Whatever may be its point of emergence, this vessel is placed beneath the in- ferior face of the caudal vertebree, between the two depressor muscles of the tail, crosses the suspensory ligament of the rectum, and extends to the extremity of the coccyx, distributing ramuscules to right and left, and even below. 4. Tlio-muscular or Ilio-lumbar Artery. (Figs. 275, 14; 277, 8.) Immediately after clearing the inferior face of the lateral angle of the sacrum, and even often before, the pelvic trunk gives off from its external side, and at a right angle, the ilio-lumbar artery, which passes directly outwards, behind the sacro-iliac articulation, between the iliacus muscle and the bony surface covered by it, and emits divisions that proceed to the above-named articulation, as well as to the muscles of the sublumbar ion. Near the angle of the haunch, it terminates in several branches, which bend upwards on the external border of the ilium, to penetrate the eae a gluteal muscle, or the muscle of the fascia lata (tensor vagine oris.) 542 THE ARTERIES, 5. Gluteal Artery. (Figs. 275, 13; 277, 7.) This, the most voluminous of the branches emanating from the pelvic _ trunk, arises opposite the preceding, and from 8-10ths of an inch to 1 ; inches behind the subsacral. It is immediately reflected on the inter Fig. 275. LATERAL VIEW OF THE GENITO-URINARY ORGANS IN THE MALE. 1, Abdominal aorta; 2, External iliac artery; 3, Common origin of the prepubic and deep femoral arteries ; 4, Prepubic artery ; 5, Posterior abdominal artery; 6 External pudic artery; 7, Subcutaneous abdominal artery; 8, Anterior dorsal artery of the penis; 9, 9, Anterior and posterior branches of that artery; 10, Internal iliac artery ; 11, Last lumbar artery ; 12, Subsacral artery; 13, Gluteal artery; 14, Iliaco-muscular artery; 15, Umbilical artery; 16, Internal pudic artery ; 17, Its vesico-prostatic branch; 18, Iliaco-femoral artery ; 19, Obturator artery ; 20, Artery of the corpus cayernosum; 21, Posterior dorsal artery of the penis—a branch of the preceding ; 22, Spermatic artery ; 23, Posterior mesen- teric artery; C, Termination of the small colon; R, Rectum; 8s, Sphincter of the anus ; /, Suspensory ligament of the penis ; 7’, Suspensory ligament of the rectum ; v, Bladder; u, Ureter; 1, Testicle; x, Epididymis; p, Deferent canal; v, Vesi- cule seminales; P, Prostate; p, Cowper’s gland; r, Crus penis; s, Ligament of the corpus cavernosum. border of the ilium, and emerges from the pelvis by the great sciatic notch, along with the anterior gluteal nerves, dividing into several branches which ramify in the texture of the great and small gluteal muscles. 6. Obturator Artery. (Figs. 275,19; 232, 10.) This vessel, the origin of which has been already indicated, directs its - y THE INTERNAL ILIAC ARTERIES. 543 course backward and downward, accompanied by a satellite vein and nerve, é passes beween the peritoneum and ilium in following the inferior border ] of the internal obturator muscle, and finally insinuates itself beneath that | muscle to make its exit from the pelvis by creeping through the oval (obtu- rator) foramen, after furnishing a constant vesical twig. Placed between the external obturator muscle and the inferior face of the ischium, it separates into several branches, the majority of which descend into the internal erural and ischio-tibial muscles (long or external vastus, and the semi- membranosis and semitendinosis), anastomosing with the ultimate divisions of the ischiatic and deep femoral arteries. Among these branches there are two or three which go to the roots of the penis, and enter the erectile tissue of the cavernous body ; one of them, more important than the others by its volume, is designated the artery of the corpus cavernosum. Anrery or tHE Corpus Cavernosum (Fig. 275, 20).—This vessel creeps on the inferior face of the ischium, backwards and inwards, reaches the crus penis, and pierces it by several branches, after supplying some muscular divisions and the posterior dorsal artery of the penis. The latter is situated on the dorsal margin of the penis, passes forward between the two ligaments attaching that organ to the symphysis pubis, 4 to anastomose with the posterior branch of the anterior dorsal and artery (Fig. 275, 21.) 7. Iliaco-femoral Artery (Figs. 275, 18 ; 277, 9.) ; Noticed as one of the terminal branches of the pelvic trunk, the iliaco- } femoral artery only exists as a vessel of a certain volume in Solipeds. In ; other animals, as in Man, it is merely an insignificant and innominate branch 4 of the obturator artery. It proceeds outside the tendon of the small psoas : muscle, between the iliacus and the neck of the ilium, which it passes round obliquely, above the origin of the anterior rectus muscle, to descend on the side of the latter, and plunge into the mass of the patellar muscles, eatering them between the anterior rectus and vastus externus, after sending out some branches to the psoas, gluteal, and muscles of the fascia lata. - DIFFERENTIAL CHARACTERS OF THE INTERNAL ILIAC ARTERIES IN OTHER THAN SOLIPED ANIMALS, 1. Internal Tliae Arteries of Ruminants. The terminal extremity of the aorta, after giving off the external iliac arteries, bifureates to constitute the pelvic trunks, and in the angle of bifurcation throws out a large branch—the sucra media—from which emanate the arteries of the tail. however, is not the only important peculiarity to be noted in the di ition of the vie arteries. The internal iliac artery emits at its origi a very short, but very large , which divides to form the umbilical artery, and an enormous wlerine artery, that supplants, to a great extent, the utero-ovarian artery; it is then directed backwards, on the internal face of the great ischiatic ligament, crossing the direction of the lumbo-sacral plexus. In its course it furnishes branches resembling the iliaco-muscular, the gluteal, and the ischiatic, and is continued about the middle of the pelvis by the a pudic artery, which terminates by forming the dorsal artery of the clitoris, after distributing branches to the rectum and the genito-urinary organs lodged in the pelvic cavity. It will be seen from this description—which refers only to female animals, but is easily applicable to males—that no mention is made of an tliaco-femoral or obturator artery. 8 is because these two vessels are entirely absent in the Sheep, and the last, é present in the Jarger Ruminants, is yet in a very rudimentary state, both being ted by the deep femoral, whose dimensions are considerable. Neither is the lateral sacral or subsacral artery described, as it is also wanting, its ischiatic branch coming directly from the pelvic trunk, and its coceygeal divisions being supplied by the middle sacral artery. | > e Ls 44 lateral bratiches, which go to right and left beneath the iliacus, and are the rep THE ARTERIES. 2. Internal Iliac Arteries of the Pig. Two single branches, originating one above the other, arise from the extren the aorta, between the two internal iliac arteries; one’ divides almost at once mity of tives of the iliaco-muscular arteries of the Horse: the other, or sacra media, placed in Fig. 276, ABDOMINAL AORTA, WITH ITS BRANCHES, IN MAN. 1, Phrenic arteries; 2, Coeliac axis; 3, Gastric artery ; 4, Hepatic artery, dividing into right and left hepatic branches; 5, Splenic artery, passing outwards to the spleen; 6, Supra- renal artery of right side;.7, Right renal artery longer than the left, passing outward to right kidney; 8, Lumbar arteries; 9, Su- perior mesenteric artery; 10, The two sper- _ matic arteries; 11, Inferior mesenteric artery ; 12, Sacra media ; 13, Common iliacs; 14, Right internal iliac; 15, External iliac; 16, Epigas- tric artery ; 17, Circumflexa ilii; 18, Common femoral artery, dividing into superficial and deep femoral. small curvature of the uterine cornu, whence it is directed forward to the ovary, — where it meets the utero-ovarian artery, after emitting numerous collateral b ‘ remarkable for the richness of the vascular network they form in the walls of the uterus. The second branch of the internal iliac artery resembles the subsacral arte/y and its mildle line, proceeds backwards on t inferior face of the os sacrum, and cor stitutes the geal urter ‘es, after giving off, at about 1} inches from its n, two. lateral branches, traces of the ae sacral arteries, which furnish the os ramusculcs of the sacral region, = The iliae trunk near its origin sends off the umbilicul artery, is directed back towards the great sciatic noteh, there detaches gluteal branches, and is pro- longed beyond the noteh to the external surface of the great ischiatic ligamentin _ forming the internal pudie artery, The latter emits, before leaving the 5 { a i | pelvic cavity, a long hemorrhoidal Pi that creeps back by the side of the a to be distributed to the posterior si mity of that intestine and the ad i genito-urinary organs, Pe vis, it ubandons some gluteal branches, _ the most considerable and CF ae which represent the ischiatie artery of — rs Solipeds. It then re-enters the cavity of the pelvis, and terminates at the base of the penis by forming the caverneus — — and dorsal arteries of that organ. ra Pe =A 3 Internal Iliac Arteries of Carnivora. The internal iliac arteries in the Car- nivora result from the bifurcation of an arterial trunk, that prolongs the aorta beyond the origin of the external ilixe as far as the first intersacral articula- tion. The pelvic trunk of the Dog at first transmits the umbilical artery, which is remarkable for its small calibre, and the flexuosities it describes before reaching the bladder, : Then the internal iliac courses for 1 or 1} inches behind, and to the inside of, the pelvi-crural venous trunk, dividing into two branches at the entrance to the pelvis, One of these branches towards the viscera contained in the pelvie cavity ; this is the internal pudic artery. It s backwards, turns the ischial ant and terminates in the cavernous and dorsal arteries of the Fey after furnishing vesical, hemorr oidal, and — urethral branches, as well as the uterine artery of the female, The latter is very voluminous, and is placed in the wae stance of the broad ligament, above the — _ i ee lOO el lr !,hLhrlc OC OUCUCUClhUh! ULC! Uh lr ee . 7 ; % 4 . ' : _ — - ‘ >. ee THE EXTERNAL ILIAC ARTERIES. 545 tschiatio branch in Solipeds; it escapes from the pelvic cavity with the great sciatic nerve, which it accompanies to behind the thigh, where it is expended, after giving off on its course spinal and gluteal twigs. It is not this branch which supplies cocey- geal arteries ; these come, as in the Pig and Ruminants, from the m sacral artery. COMPARISON OF THE INTERNAL ILIAC ARTERIES IN MAN WITH THOSE OF ANIMALS, The aorta in Man bifureates at the fourth lumbar vertebra to form the primitive (or common) iliac arteries, which descend to each side of the margin of the pelvis, where ee a pag rai the internal and alg ao as i iliac, or hypogastric artery, passes beneat e sacro-iliac articulation, and breaks up into nine a eleven branches that go to the walls of the pelvic cavity, or to the organs contained in it. Their disposition somewhat resembles that of Car- nivora; in their distribution they represent the various branches of the internal iliac of ne Thus we find: 1, An umbilical artery ; 2, The vesico-prostatic artery, re- ing the branch of the same name given off in the Horse by the internal pudic ; 3, The middle hemorrhoidal artery, that passes to the rectum like the branch of the internal pudic ; 4, The ileo-lumbar artery, the iliaco-muscular of Solipeds; 5, The lateral sacrul artery, which, behind, joins the middle sacral instead of dividing, as in the Horse, into ischiatic and lateral coceygeal; 6, The obturator artery ; 7, Gluteal artery; 8, Is- chiatie; 9, Internal pudic, that terminates, as in animals, by the cavernous, dorsalis penis, and the transversa perinei arteries. The arterial branches of the rectum, or inferior hemorrhoidal, are furnished by the internal pudic artery. Artiote [V.—Exrernat Iniac Anrertss orn Crurat Trungs. (Fig. 277, 11.) The external branches of the terminal quadrifurcations of the posterior aorta, the crural trunks descend on the sides of the entrance to the pelvic cavity, in describing a curve downwards and forwards, and a direction oblique from above to below, before to behind, and within outwards. Maintained within the small psoas and iliacus muscles by the peritoneum covering them, they are bordered posteriorly, and to the inner side, by the iliac vein, which isolates them from the pelvic trunk. When they arrive at the anterior border of the pubis, in the interstice which separates the pectineus from the long adductor of the leg, each is prolonged to the thigh, and takes the name of femoral artery ; and thence into the angle of the femoro-tibial articulation, where it receives the denomination of popliteal artery. Before passing to the description of these two vessels—continuations of the external iliac artery, we will indicate the collateral branches which emanate from this trunk itself. These are two principal: the small testicular or uterine (cremasteric), and the circumflexa ilii. The first having been already described (p. 534), we have only to notice the second. i Cirmcumriex Iniac Artery (Fig. 272, 11).—This artery commences at an acute angle near the origin, and in front of, the external iliac; it sometimes emerges directly from the abdominal aorta. It is directed outwards, passes between the peritoneum and the lumbo-iliac aponcurosis, and arriving at the external border of the great psoas muscle, or even beyond that, it bifurcates. The anterior branch sends its ramifications into the transverse and small oblique muscles of the abdomen, where they anastomose with the abdominal ramuscules of the lumbar and intercostal branches; the posterior bifurcation, after giving some vessels to the same muscles, traverses the abdominal wall a little below the external angle of the ilium, in passing between the small oblique and iliacus muscles, to descend within the anterior border of the ilio-aponcuroticus (tensor vagine) muscle, and expend itself in front of the thigh by subcutancous divisions, 2N THE ARTERIES. Fig. 277. (Be as (Le Sen ers ( sgh 2 PE PNNRNENAME IT ' am d . * DISTRIBUTION OF THE EXTERNAL AND INTERNAL ILIAC ARTERIES IN THE MARE, 1, Abdominal aorta; 2, Internal iliac artery ; 3, Common origin of the internal pudie and the umbilical arteries—the latter is cut; 4, Internal pudie artery; 5, Vaginal artery; 6, Lateral sacral artery; 7, Origin of the gluteal artery, which springs in this instance from the —— sacra], a circumstance most frequently observed in the Ass; 8, Origin of the Mo-asaboular artery; 9, Origin of the iliaco-femoral artery; 10, Obturator artery; 11, External iliac artery; 12, Cir- eumflex iliac artery, cut; 13, Femoral artery; 14, Common origin of the deep femoral and prepubic arteries; 15, Origin of the anterior great muscular artery; 16, — Origin of the saphena artery, cut; 17, Innominate branch; 18, Popliteal artery ; 19, Femoro-popliteal ; 20, Satellite artery of the great femoro-popliteal nerve; 21, Posterior tibial artery; 22, Its communicating branch with the saphena; 23, Ex- ternal plantar artery; 24, Satellite artery of the internal plantar nerve; 25, Digital artery. THE EXTERNAL ILIAC ARTERIES. 547 FEMORAL ARTERY. (Fig. 277, 13). The femoral artery, a prolongation of the external iliac, which changes its name on leaving the anterior border of the pubis, at first lies beneath the __ erural arch, beside a cluster of lymphatic glands, in the space comprised _ between the pectineal muscles, the long adductor of the leg, and the iliacus. From this interstice it descends, accompanied by its satellite vein, which lies behind it, and the internal saphena nerve, along the pectineus and vastus internus, at the posterior border of the long adductor of the leg. It soon leaves that muscle, however, to traverse the ring formed by the two branches of the t adductor of the thigh and the oblique concavity on the posterior face of the femur, and reaches the superior extremity of the gastrocnemii, between which it is continued, and assumes the name of popliteal artery. ; On its course the femoral artery distributes a certain number of collateral branches to the adjacent parts. These are: the prepubic, deep muscular, superficial muscular, the small muscular, and saphena arteries. Preparation.—The animal being placed in the first position, and the limb raised, the skin is carefully removed from the inner aspect of the thigh, the external generative organs in the inguinal region, and the inferior abdominal wall. The saphena vein is first to be exposed, and the branches of the artery of that name dissected; next, the bie artery, which is to be sought for in the inguinal canal, and its branches _ prepared l-y dissecting from their origin to their termination. The excision of a portion of the adductors of the leg, and the great adductor of the thigh will sufficiently expose _ the femoral artery and its other collateral branches. 1. Prepubie Artery. (Fig. 275, 4.) This artery originates at the artificial line of demarcation which separates the external iliac from the femoral artery, at the superior extremity of the latter. It therefore emerges from that vessel at the anterior border of _ the pubis, and never alone, but always with the deep muscular branch, by means of a common and generally very short trunk, which springs at an acute angle from the inner side of the femoral artery. The prepubic artery traverses the crural ring, opposite which it arises; it lies on the anterior face of Poupart’s ligament, behind the neck of the vaginal sheath, and after a very short course separates into two branehes— the a. abdominal and external pudic arteries. i osterton Appominat Artery (Epigastric of Man)—(Fig. 275, 5).— This leaves the external pudic artcry at an acute angle, enters the femoral ring by crossing the direction of the spermatic cord, places itself between the small oblique and transverse muscles of the abdomen, passes forward _ along the external border of the great rectus muscle, and finally enters the ' substance of that muscle, where its terminal divisions anastomose with: those of the anterior abdominal-artery. The numerous collateral branches this artery throws off on its track principally go to the rectus muscle, or the ther parts composing the inferior abdominal wall, the skin included; the perior branches communicate with the circumflexa ilii. __ The position this artery occupies at its origin, and with reference to the abdominal ring, is worthy of remark; indicating, as it does, that in angulated inguinal hernia division of the ring should be made outwards, wounding the vessel. . ‘ _ Exrernat Poupic Aureny (Fig. 275, 6).—This artery descends at first on the posterior wall of the inguinal canal, behind, and a little to the inside _ of, the spermatic cord ; then, having passed the inferior ring of the canal, it 2n 2 - — =. aes 548 THE ARTERIES. bifurcates into the subcutaneous abdominal artery, and the anterior dorsal artery of the penis. The subcutaneous abdominal artery is directed forward on the superficial face of the abdominal tunic, bordering in its course the insertion of the suspensory ligament of the sheath. Arriving at the anterior extremity of that ligament, it terminates in several subcutaneous divisions, one of Pcs which is inflected beyond the umbilicus to anastomose en arcade with — a similar branch from the opposite artery. It gives off twigs to the scrotum, sheath, superficial inguinal glands, skin, &c. (Fig. 275, 7). The anterior dorsal artery of the penis gains the superior border of that organ, after supplying one or two scrotal branches, and separates into two portions ; one, posterior, meets the dorsal cavernous artery of the penis and anastomoses with it; the other, anterior, longer, more voluminous, and very flexuous during retraction of the penis, follows the dorsal border of the organ to its anterior extremity, where it enters the erectile tissue that forms this part. From the two branches of this anterior dorsal artery, there are given off, as in the posterior one, ramuscules which penetrate the corpus cavernosum, and the walls of the urethra; they give, besides, some preputial twigs (Fig. 275, 8). In the rematr, the external pudic artery offers a disposition which, if not similar, is yet analogous to that just indicated. As in the male, this vessel traverses the inguinal canal, and after leaving it divides into two branches: one, the anterior, or subcutaneous abdominal artery, the other the posterior, or mammary artery. The last, the most voluminous. represents the dorsal artery of the penis. It distributes several branches to the mammary tissue, and is prolonged between the thighs by a perineal branch, which terminates in the inferior commissure of the vulva, after giving off glandular and cutaneous branches, 2. Profunda Femoris, Great Posterior Muscular Artery of the Thigh, or Deep Muscular Artery. (Fig. 277, 14), Arising in common with the prepubic artery, the profunda femoris passes backward, penetrates between the iliacus and the pectineus muscles, afterwards between the latter and the external obturator muscle. In this way it arrives beneath the deep face of the adductors of the thigh, when it becomes inflected behind the femur, and disappears in the substance of the internal and posterior crural muscles by ascending branches, which anastomose with the ischiatic artery, and descending and internal branches, whose terminal ramifications open into those of the obturator artery. The principal twigs of the coxo-femoral articulation are derived from this vessel, 8, Superficial Muscular, or Great Anterior Muscular Artery. (Fig. 277, 15.) Smaller than the preceding, and commencing opposite to it, but a little lower, this artery passes downwards, outwards, and forwards, runs between the long adductor of the leg and the musculo-tendinous cone which terminates in common the psoas magnus and iliacus, furnishes some ramuscules to these muscles, dips into the interstice separating the vastus internus from the anterior rectus of the thigh, and is lost in the mass of the triceps cruris. This vessel, therefore, resembles the iliaco-femoral artery, which we observed to enter this triceps by penetrating between the anterior rectus and the vastus externus. ——— ee i eth De laa | Es Se ee ——— i THE EXTERNAL ILIAC ARTERIES. 549 4. Innominate or Small Muscular Arteries. The femoral artery gives off on its course numerous small branches destined for the neighbouring muscles, though too diminutive to merit parti- cular description. One of these furnishes the nutritive artery of the femur, the largest, perhaps, of all the arteries supplying bones. Another (Fig. 277, 17) sends to the stifle a long articular branch, analogous to the great anastomoticus of Man, which descends along the vastus internus, beneath the adductors of the leg, at the interstice which separates these two muscles. 5. Saphena Artery. (Fig. 277, 16.) This artery, remarkable for its small volume, the length of its course, and its connections with the vein whose name it bears, is destined for the skin on the inner side of the thigh and leg. , Tt takes its origin at an acute angle, from nearly the middle of the femoral artery, either alone or in common with one of the principal innominate muscular branches, and becomes superficial in passing into the interstice of the two adductors of the leg, or in traversing one of these, usually the short one or gracilis. It lies on the surface of this muscle, beside the saphena vein, and bifurcates at the angle of union of the two roots which constitute that vessel. One of the branches accompanies the anterior vein to nearly the lower third of the leg ; the other follows the posterior vein, and usually anastomoses in the hollow of the hock, above the calcaneus, with a branch from the posterior tibial artery, and which also communicates with one of the branches of the femoro-popliteal artery. Popliteal Artery. (Fig. 277, 18.) Preparation.—The preparation which has served for the study of the femoral artery being nearly arranged as in figure 277, remove from it the internal gastrocnemius and popliteus muscles. The above name is given to the continuation of the femoral artery. This vessel follows a descending direction behind the femoro-tibial articula- tion, between the two gastrocnemii muscles, insinuates itself beneath the popliteus, and bifurcates at the peroneal arch after a course of from 6 to 8 inches, to form the posterior and anterior tibial arteries. The popliteal artery emits on its track: 1, The femoro-popliteal ving - 2, Articular branches; 3, Muscular branches chiefly destined to the anger muscles, of which it is necessary to particularise one long ivision that descends within the perforatus, in company with the great femoro-popliteal nerve, to terminate superficially near the tendo-Achillis, where it anastomoses with a recurrent branch of the posterior tibial © artery (Fig. 277, 20). The femoro-popliteal artery is the only one of these collateral branches ing particular mention. Its origin indicates the limit of the femoral and popliteal arteries, as it is detached at a right angle below the ring of a greet abductor of the thigh, at the intermediate point of these two Placed between the semimembranosis and semitendinosis muscles on the one part, and the long vastus on the other, this vessel is directed from before to behind, and arrives at nearly the rior border of the buttock, where it terminates in subcutaneous branches, after emitting descending and ascending branches. Among the first of these, which are ' principally destined to the gastrocnemii muscles, sometimes exists the —— —— - 550 THE ARTERIES. a satellite branch of the sciatic nerve, and a thin twig which descends with the external saphena nerve into the hollow of the hock, where it meets, like — ae ' the preceding, a branch of the posterior tibial artery. Several of the ascending branches pass along the great femoro-popliteal nerve, and all anastomose either with the deep femoral, or with the ischiatic arteries in the’ substance or interstices of the ischio-tibial muscles (Fig. 277, 19): ree i Vee TERMINAL BRANOHES OF THE POPLITEAL ARTERY. —— 1. Posterior Tibial Artery. (Fig. 277, 21.) Preparation.—Follow the indications furnished by figure 277. “he At first situated deeply behind the tibia, beneath the popliteal muscles __ and the oblique and deep flexors of the phalanges, this artery descends _ towards the hollow of the hock, becoming gradually more and more super- a ficial, and lying below the tibial fascia, behind the tendon of the oblique _ flexor muscle, along with its satellite vein. Arriving at the apex of the By! os calcis, it crosses the precited fascia, describes an § curve, and, eo with the sciatic nerve, passes beneath the tarsal arch; at the astragalus it separates into two terminal branches—the plantar arteries. ee ey Collateral branches.—We cite: 1, Numerous branches destined to the | posterior deep tibial muscles; 2, The medullary artery of the tibia; 8,The __ tarsal articular arteries, a principal of which, with a large venous arch, under the perforans, near the inferior extremity of the tibia, to be distributed outside the tarsus by descending ramuscules and ascending twigs, which extend as far as the gastrocnemii tendons; 4, A superficial ascending | branch, arising ordinarily from the second inflexion of the 8 curvature formed by the artery at its lower extremity, situated in the hollow of the hock, anastomosing with the saphena artery, as well as with the satellite popliteal branch of the sciatic nerve, and whose ramifications, nearly all subcutaneous, are scattered, within and without, on the sides of the hock and the inferior extremity of the thigh. Terminal branches.—The two terminal branches of the posterior tibial artery are slender vessels, vestiges of the plantar arteries in Man. Lying on the outer side of the synovial tendinous sheath lining the tarsal groove, they _ are placed, one within, the other without, the perforans tendon, and descend along with the plantar nerves to the upper extremity of the meta where they leave the nerves, each to anastomose with the perforating pedal artery, and form a kind of deep arcade across the upper extremity of the suspensory ligament of the fetlock: that is, from the post-metatarsal fibrous band which represents the interosseous plantar muscles of tetradactylous or — pentadactylous animals. | In their course, these plantar arteries only distribute some insignificant ramuscules to the tarsal articulations. : ‘a2 From the convexity of the arch they form in uniting with the perforating — pedal artery, arise four long descending branches: 1, Two superficial : innominate and very fine twigs accompanying the plantar nerves, and creeping by the side of the flexor tendons to the sesamoid groove, where they inosculate with the collaterals of the digit (Figs. 277, 24; 278, 8); 2, Two deep branches constituting the plantar interosseous arteries, Bs tinguished into eternal and internal. The first is only an extremely fine — vascular thread, very uncertain in its disposition, and possesses no other — importance in Solipeds than representing, in a rudimentary. state, an t Loe THE EXTERNAL ILIAC ARTERIES. 551 artery which is of considerable size in other animals. Placed within the external metatarsal bone, it anastomoses, by its inferior extremity, with a branch of the metatarsal pedal artery. Te internal interosseous plantar artery may be considered, if we would neglect the study of analogies, as the continua- tion of the perforating pedal artery, which it rivals in volume. It descends to the external side of the internal metatarsal bone, beneath the margin of the suspensory ligament of the fetlock, and terminates a little above the tubercle of the external metatarsal bone, in uniting at a very acute angle with the _ metatarso-pedal artery. It gives off on its tract: the medullary branch of the principal metatarsal bone; a small branch to the external interosseous artery; several ramuscules which transversely cross the posterior border of the internal metatarsal bone to supply the cellular tissue, the skin, and _ the tendons applied to the median metatarsal bone. 2. Anterior Tibial Artery. (Fig. 278, 1.) Preparation.—Expose the artery by removing the anterior muscles of the leg. The anterior tibial artery is the largest of the two branches terminating the popliteal trunk. It traverses the tibial or tibio-peroneal arch, and, with its satellite veins, places itself on the anterior aspect of the tibia, down which it passes by following the deep face of the flexor muscle of the metatarsus. On reaching the front of the tibio-tarsal articulation, it loses its name and takes that of the pedal artery. The anterior tibial artery gives off a great number of collateral branches, which are principally distributed among the tibial muscles. One of them, descending along the fibula, beneath the lateral extensor muscle of the phalanges, clearly represents a trace of the peroneal artery of Man. 3. Pedal Artery. (Fig. 278, 1'.) A continuation of the anterior tibial artery, whose name changes on its arrival in the region of the foot, the pedal artery courses downward over the anterior face of the tibio-tarsal articulation, by bending slightly outwards, and ing beneath the cuboid branch of the flexor muscle of the metatarsus. At the second row of tarsal bones it divides into two branches, which we will designate the perforating pedal, and the metatarso-pedal arteries,’ the latter continued inferiorly by the digital arteries, or collaterals of the digit. The collateral branches emanating from this vessel are all articular cutaneous, and of no importance.” Perroratinc Pepau Arrery.—It crosses the tarsus from before to behind, by passing, with a venous branch, into the canal between the euboid, scaphoid, and great cuneiform bones; it then joins the arch formed by the anastomoses of the two plantar arteries—terminal divisions of the posterior tibial (Fig. 278, 2). Merararso-pepaL on Coizarerat Artery or THE Cannon.2—Much 1 The vessel we have here named the drone Ep artery is only the like termination of the same artery in Man. The metatarso-pedal artery ought to be regarded as the representative of one of the dorsal interossei arteries, because of its position in the interstice of the middle and external lateral metatarsal bones. The dorsal interstice of the inner side also lodges an interosseous branch, usually supplied by the external eee artery : but its ameter is so diminished that, in order to avoid complexity by in g an almost useless element into the didactic description of the posterior tibial . we have thought it our duty to neglect its indication. ? One of these may be regarded as the analogue of the dorsalis pedis of Man. 3 Rigot has designated this artery—we do not know why—the superficial plantar artery. 552 THE ARTERIES. larger than the preceding, this vessel (Fig. 278, 3) may be considered as a continuation of the primitive pedal artery. It is lodged at first in the fissure situated outside the middle metatarsal bone, in front of the external metatarsal bone, and afterwards passes between. these two bones, above the tubercle terminating tho latter, reaching the posterior face of the first, PRINCIPAL ARTERIES AND VEINS OF THE POSTERIOR FOOT. 1, Anterior tibial ar- tery; 1’, Pedal ar- tery; 2, Perfora- ting pedal artery ; 3, Reassiniopéiel, or collateral artery of the cannon; 4, Digital artery ; 5, Anterior tibial ar- tery; 6, Posterior root of the internal saphena vein; 7, Origin of the ex- ternal saphena vein; 8, 9, 10, Metatarsal veins; 11, Digital vein; 12, Venous plexus of the foot, between the two inferior branches of the suspensory ligament, above the sesamoid groove, where the vessel bifurcates to form the collateral arteries of the digit. The collateral artery of the cannon receives, a short distance above this terminal bifurcation, the internal plantar interosseous artery. On its course it gives off: 1, Numerous anterior ramuscules for the cellular tissue, tendons, ligaments, and the skin on the anterior face of the metatarsus and fetlock ; 2, Some thin posterior divisions, one of which ascends within the external metatarsal bone to anastomose with the external plantar interossecous artery, after fur- nishing several ligamentous, tendinous, and cutaneous — ramuscules in the posterior metatarsal region. DierraL ARTERIES, OR COLLATERAL ARTERIES OF THE Diair (Figs. 277, 25; 278, 4; 283, 11).—Remarkable for their volume, these arteries carry blood to the keratogenous apparatus enveloping the ungueal phalanx, and from this destination derive such importance that they deserve a detailed study. Origin—The digital arteries succeed the terminal extremity of the collateral of the cannon, and separate from one another in forming an acute angle below the sesamoid venous arch, above the fetlock joint, between the two branches of the suspensory ligament, behind the inferior extremity of the principal metatarsal bone, and in front of the flexor tendons of the phalanges. Course and Relations.—These vessels descend, one to the right, the other to the left, from the lateral parts of the metacarpo-phalangeal (and metatarso-phalangeal) articulation to the internal face of the basilar process, where they bifurcate to form the plantar and preplantar ungueal arteries. “In the whole of this course, it (the digital artery) follows the track of the flexor tendons, on whose margi it rests, and where it is maintained by loose connective tissue. Behind, it is flanked by the plantar nerve, which It would have been better to have allowed it to retain the name given to it by Girard—the lateral artery of the cannon. This is not the only instance in which the attempts of Rigot to conform the nomenclature of the arteries to that of anthropotomists has ed unfortunate, as he has not always succeeded in finding In the Horse the real representatives of arteries in Man. The aim of this work does not allow us to discuss the vicious determinations and denominations of Rigot every time we meet them. We are content to change them, pees and simply, leaving to the judgment of the reader, should this matter interest him, the task of deciding if we are right, — CU ail =a ? Ve re: ee THE EXTERNAL ILIAC ARTERIES. 553 covers a portion of its surface, enlaces it with numerous filaments, and is so closely associated with it in all its flexuosities as to form but a single cord with it. “Tn front, it is margined, though for a short distance, by its satellite vein, which for the whole of its track rests on the lateral faces of the two first phalanges. . ** At its upper part, near its origin, and on the lateral portions of the metacarpo-phalangeal articulation, the digital artery is crossed from behind to before by the anterior branch of the plantar nerve, and it is covered for the whole of its extent by the fascia which continues the proper tunic of the a cushion, whose lateral ligamentous band cuts its direction obliquely above to below and behind to before, at the middle portion of the first Collateral divisions.—These are: 1. At the fetlock, numerous fine branches distributed to the metacarpo-phalangeal articulation, but par- ticularly to the sesamoid sheath, and the tendons lodged in it. 2. To the environs of the upper extremity of the first phalanx, a slightly ascending and sometimes voluminous twig, for the tissue of the ergot (the horny tubercle behind the fetlock). 8. Towards the middle of the same bone, the vessel named by Percivall the perpendicular artery, and correctly so, for it arises at a right angle from the digital artery to divide almost immediately afterwards into two series of ramifications—anterior and posterior’ The anterior branches are in nearly 7 instance two principal: one ascending, passing beneath the check of the extensor tendon, and climbing to the capsular ligament of the fetlock joint to meet the arterial divisions furnished directly to that ligament by the collateral artery of the cannon ; the other descending, which reaches the side of the second phalanx, where its ramuscules anastomose with the - coronary circle and the circumflex artery of the coronary substance (cushion). The posterior ramifications consist most frequently of two principal branches, —one ascending, the other descending ; these insinuate themselves between the flexor tendons and the sesamoid ligamenis, to be distributed to these organs, but especially to the synovial membrane lining the large sesamoidean sheath. Sometimes it is seen to arise alone from the digital artery. It must here be noted, that the divisions furnished by the anterior branches of this dicular artery communicate with those of the opposite side in front of the first phalanx, either above or below the principal extensor of the digit; and that the posterior branches exhibit a series of analogous anasto- moses. The body of the first phalanx is therefore enveloped on every side by an arterial plexus. 4. At different elevations on the first ana second phalanges, several tendinous and cutaneous twigs, which are of no importance. 5. The artery of the plantar cushion, which arises at the superior border of the lateral cartilage, is directed obliquely backward and downward, and placed within the posterior border of that cartilage, to be distributed to the middle portion of the complementary apparatus of the third phalanx, as well as to the villous tissue and the coronet. The branch expended in the latter sometimes proceeds directly from the digital artery; it is a very _ remarkable vesssel, is inflected from before to behind, crossing the posterior border of the pedal cartilage, creeping on the internal face or in the texture of the skin, a little above the coronet, parallel with that portion of the ' H. Bouley.—‘ Traité de Organisation du Pied du Cheval.’ Paris, 1851. 554 THE ARTERIES. keratogenous apparatus, and terminates by anastomosing with a branch Fe = the artery now to be noticed. } 6. The coronary circle,’ formed by two transverse branches—one anterior, the other posterior, springing at a right angle from the digital artery, under ~ the cartilaginous plate of the os pedis—passes around the coronary bone to meet the analogous branches of the opposite artery, to anastomose with them __ directly and by inosculation. The coronary circle therefore presents two : : distinct portions: one posterior, placed above the superior border of thesmall sesamoid, beneath the perforans tendon ; the other anterior, more extensive —_ and voluminous, covered on the sides by the lateral cartilages of the foot, and in its front or middle part by the expansion of the anterior extensor tendon of the phalanges. The collateral ramuscules furnished by the posterior part of the circle are small, few, and of no interest. | Among the branches arising from the anterior portion, there is only a single pair of arteries to be noted, which are remarkable for their mode of distribution and their volume. They originate near the border of the extensor tendon, and immediately divide into two divergent branches: : one the internal, which passes acrcss that tendon to anastomose with the = homologous branch of the opposite side; the other, external, passes backward to meet the cutigeral branch furnished by the artery of the plantar cushion, and joins that vessel. From this disposition results a very fine superficial vascular arch around the. coronet, which is well named the circumflex artery of the coronary cushion; it is situated a little above the cutidural artery, beneath the skin of the coronet, and looks as if inerusted in that membrane; by its two extremities it rests on the arteries of the : plantar cushion, and is fed by the two principal vessels of the cor circle; while it furnishes ascending anastomosing ramuscules to the inferior divisions of the perpendicular artery, as well as numerous descending branches passing into the coronary cushion and the laminal tissue of the foot. Such is the ordinary disposition of the coronary circle and its super- ficial arch—the circumflex artery of the coronary substance ; though it varies much in different animals, and even in the feet of the same animal. To attempt to describe here the variations we have seen would be supererogatory, and we may limit ourselves to saying that these varieties were almost exclusively confined to the origin of the branches composing these two circular vessels and their manner of arrangement, without modifying in any way the general — disposition of the circles.” Terminal divisions. —These are, as kas becn already mentioned, the plantar — and oe tet ungueal arteries.* . The preplantar ungueal artery is the smallest of these two terminal ‘asiches. Situated at first inside the basilar process of the third phalanx, it turns round this to traverse the notch which separates this process from the retrossal eminence, is lodged with a satellite nerve in the preplantar 1 So named because it encircles the coronet. 2 We may notice here one of these variations, which is somewhat frequently met — with in the anterior limb. This consists in the anterior descending branch of the — perpendicular artery uniting at its terminal extremity with the circumflex artery of the coronary substance, which it concurs to form. % In all treatises on anatomy these vessels are simpl y designated the plantar and preplantar arteries. We have added the epithet ungueal to distinguish these arteries from the properly so-cailel plantar branches—the terminal divisions of the poem 3 tibial artery. - THE EXTERNAL ILIAC ARTERIES. 555 - fissure, which it crosses from before to behind, and terminates near its anterior extremity by several divisions that bury themselves in the os pedis. In its course, it distributes: 1, Before passing into the sub-basilar notch, a deep retrograde branch destined to the: bulb of the heel and the. villous tissue; 2, Immediately after leaving that notch, a second retrograde branch, whose divisions pass backward, behind the great circumflex artery of the pedal bone ; 3, During its passage in the preplantar fissure, several ascend- ing and descending branches which ramify in the laminal tissue; the first. -anastomose with the descending divisions of the coronary circle and the circumflex artery of the coronary cushion. b. The plantar ungueal artery ought to be regarded as a continuation of the digital artery, because of its volume and direction. Lodged at first, with a fine nervous branch, in the plantar fissure, it afterwards enters the canal of the same name, and thus penetrates into the semilunar sinus of the os pedis, where it anastomoses by inosculation with the opposite artery, forming a deep vascular arcade which we designate the plantar arcade or circle, or, after M. H. Bouley, the semilunar anastomosis (Fig. 283, 12). Two orders of branches emanate from the convexity formed by this anastomotic loop. The ascending order “ irradiate in the spongy framework of the third phalanx, and like so many hair-roots, escape by numerous open- ings from its anterior face, where they form a very intricate plexus by anasto- mosing, in the texture of the laminal tissue, with the extreme divisions of the anterior branch of the digital artery and those of the coronary circle. ... . f Tt is to these divisions that Spooner has given the name of anterior laminal arteries.” —H. Bouley. The descending order, much more considerable, named by Spooner (W. C., of Southampton) the inferior communicating arteries, arise at a right angle from the anterior circumference of the semilunar anastomosis, traverse in a diver- gent manner the tissue of the phalanx, and make their exit by the large fora- _ mina situated a little above the inferior border of the bone, where they furnish a multitude of ascending ramuscules which concur to form the arterial net- work of the laminal tissue. “'Then they anastomose transversely by a succession of little arcades which are thrown from one to the other, and in this way give rise to a great circumflex canal which follows the contour of the parabolic curve exhibited by the thin border of the os pedis, on its inferior face.”’"—H. Bouley. This vascular arcade, which we purpose naming the in- ferior circumflex artery of the foot, to distinguish it from the circumflex of the coronary cushion, is joined by its extremities to the preplantar artery, in the same manner that the latter circumflex is united to the artery of the plantar cushion. From its concavity it throws off some fourteen or fifteen con- yergent branches, which are destined to the villous tissue of the sole. DIFFERENTIAL CHARACTERS OF THE EXTERNAL ILIACS IN OTHER THAN SOLIPED ANIMALS. 1. External Iliae Arteries of Ruminants. In the Oz, apart from the considerable volume of the great muscular arteries of the thigh, the crural trunk, as well as the femoral and popliteal arteries continuing it, comport themselves almost tlie same as in the Horse. It is only when we reach the posterior and anterior tibial arteries that we find some peculiarities worthy of notice. Posterior tibial artery —Much more voluminous t)an that of Solipeds, this artery follows the same track, and terminates in an analogous manner: forming at its lower extremity two plantar branches, which anastomose with the perforating pedal artery behind the superior extremity of the principal metatarsal bone, and beneath the suspensory ligament. But these two branches are fur from possessing the same volume; the internal is in- comparably the largest, and appcars to be the direct continuation of the posterior tibial artery. 556 THE ARTERIES. From this anastomosis results, as in the Horse, two series of metatarsal branches—a profound and a eyecare . The profound branches, two or three in number, form on the posterior face of the metatarsal bone, below the suspensory ligament, the posterior interosses, mixed with two or three reticulated venous’ branches, and anastomose by their inferior extremity with a perforating branch of the collateral of the cannon. The superficial branches, similar to those which accompany the plantar nerves in the Horse, are of very unequal calibre: the external is so rudimentary tliat it often escapes dissection ; the internal in reality continues the plautar artery of tue same side, Both are united to the perforating branch already nakioed: Anterior tibial artery.—After passing down along the leg on its antero-external as in Solipeds, this vessel arrives on the hock, where it takes the name of artery, and furnishes the perforating pedal artery ; it is coutinued by the metatarso-pedal or collateral artery of the cannon. a. The perforating pedal artery does not differ from that of the Horse. b. The metatarso-pedal, or collateral of the cannon, descends, flanked by two satellite veins, in the channel on the anterior face of the metutarsul bone, giving off towards the inferior extremity of that channel the perforating branch already spoken of, and is continued into the digital region as the common digital artery. The perforating branch of the collateral of the cannon passes iuto the foramen pierced from before to behind, across the inferior extremity of the metatarsal bone, arriving — beneath the suspensory ligament, and then divides into several ascending and i branches. The first join the deep and superficial posterior metatarsal arteries furni by the plantar and pedal perforating arteries. Among the second, we notice three digital arteries, fac-similes in miniature of those which will be described in the anterior limb: two literal, descending on the excentric side of the phalanges; a median, turning within the flexor tendons to place itself behind them on the middle line of the digital region, and prolonged into the interdigital space, where it anastomoses with a branch of the principal artery of the digits. The latter artery, the common digital, descends into the space between the digits, after passing beneath the capsular ligament of the metatarso-phalangeal articulations, in the notch comprised between the two articular surfaces of the metatarsal bone, and terminates above the inferior extremity of the first phalanx by two ungueal arteries, whose description will be reserved until describing the arteries of the anterior limb, In the number of collateral branches emanating from this vessel, there muy be particularly remarked a large off-shoot which arises a little before the separation of the two ungueal arteries, and is directed from before to behind, dividing at the posterior part of the interdigital space into several divisions, the principal of which are: 1, Two transverse branches passing between the flexor tendons and the phalanges, to be joined to the lateral digital arteries; 2, A single ascending branch, joining with the posterior median digital artery; 3, A descending “besnch, also single, dividing into two portions which reach the heels, to be distributed to the plantar cushion and tle villous tissue. These branches represent the arteries of the plantar cushion in tiie Horse, and will be noticed more in detail in the description of tie arteries of the anterior limb, where in principle they are found to be exactly like these. 2. External Iliae Arteries of the Pig. The distribution of these vessels in the Pig is remarkably like that we have described as existing in Ruminants, even in the terminal portions of the limbs, notwithstanding the complete development of the two lateral digits. It may be noted, however, that the posterior tibial artery is somewhat slender, and that it is singularly reinforced by its anustomosis with the saphena artery, whose dimensions are relatively considerable." 8. External Iliac Arteries of Carnivora. . The crural trunk is divided in the Carnivora, as in the other animals, into three sections: the proper iliac artery, the femoral artery, and the popliteal artery, by the tibial branches. Proper iliae artery—This vessel does not give rise to any branch, as the eir- cumflexa ilit comes directly from the abdominal aorta. 1 In small Ruminants, the posterior tibial artery, properly speaking, is equally rudimentary; the saphena artery constitutes the principal vessel. From a note whic we made a long time ago, it appears the first vessel is altogether absent sometimes, and that the plantar divisions come exclusively from tlie saphena, as in the Carnivora. — , ee THE EXTERNAL ILIAC ARTERIES, 557 Femoral artery.—As in the Horse, this gives off: 1, Several muscular innominate branches ; 2, Two great muscular arteries, the posterior of which furnishes the prepubic artery ; 3, A saphenal branch. In the Bitch, the external pudic artery, emanating from the prepubic division, presents some peculiarities in its distribution: it gives off a long branch which is placed in the texture of the mamme, and passes forward to meet and unite with the mammary branch furnished by the internal thoracic artery; it then runs between the two thighs in a flexuous manner, and reaches the lips of the vulva, where it ends in numerous ramuscules that anastomose with the vulvular divisions of the internal pudic artery. The saphena artery is as remarkable for its large volume as for its destination. It descends on the internal face of the leg, furnishing numerous subcutaneous divisions, and terminates at the hock by several slender plantar twigs, which accompany the flexor tendons. Among the branches given off by this vessel in its course, it is necessary to distinguish two: one which follows the anterior branch of the saphena vein to the hock, where it communicates by its terminal divisions with the tarsal artery; the other arises a little lower, passes beneath the phalangeal flexor muscles, and is expended on the _ hock in articular and malleolar branches. In the latter branch we see a trace of the peroneal of Man. The saphena itself, considered as a whole, and particularly towards its inferior moiety, supplements the posterior tibial artery. Sh gta a .—This artery gives an important femoro-popliteal branch, and enters the tibio-peroneal arcade to constitute the anterior tibial artery, after distributing on its course muscular ramuscules—rudiments of the posterior tibial artery of other animals. The anterior tibial artery, arriving in front of the hock, detaches the tarsal artery : a voluminous branch divided near its origin into several superficial superior and inferior branches. It continues to descend, traverses from before to behind the superior part of the third intermetatarsal space, and terminates by an arterial arcade situated beneath the flexor tendons; from ii aoa emanate ascending divisions, which anastomose with the plantar arteries, and three large descending or digital branches, which affect the seme disposition as three analogous principal arteries emanating from the superficial palmar arcade of the anterior limb. COMPARISON OF THE EXTERNAL ILIACS OF MAN WITH THOSE OF ANIMALS. In Man, the external iliac forms the external branch of the bifurcation of the common iliac; it extends to the crural arch, where it takes the name of femoral artery. It furnishes the cireumflexa ilii and epigastric: the latter resembling, in its distribution, the ' osqy-and abdominal branch given off by the prepubic artery in the Horse. he femoral artery has the same general disposition as in animals, and almost the same teral branches. There is no prepubic artery; the divisions furnished by this trunk in Solipeds originate separately from the femoral artery; these are: the abdominal tegumental artery (superficial epigastric), and the external pudie arteries—the one re-~ sembling the subcutaneous abdominal artery, and the others the branches of the external pudic artery of animals. The popliteal artery is a superficial vessel situated at the posterior face of the knee- joint, in a lozenge-shaped space limited by the muscles of the region, and named the popliteal space. At the tibio-peroneal arch it bifureates, and constitutes the anterior tibial and the tibio-peroneal trunks. The tibio-peroneal trunk does not exist in animals in which the peroneal artery is in a rudimentary state, in consequence of the feeble development of the peroneus. This trunk is short, and furnishes the nutrient artery of the tibia, then divides into the peroneal and posterior tibial arteries. The first descends to the external malleolus, along the inner face of the tibia, and terminates in two branclies, one of which, the anterior peroneal, communicates with the dorsal artery of the tarsus—a branch of the pedal. he posterior tibial, on reaching the concavity of the calcis, constitutes the and external plantar arteries. The internal plantar is directed forwards, beneath the sole of the foot. and is lost in the muscles of the great toe, or forms the collateral of the latter vessel. Beneath the tarsal articulations, the external plantar describes a curve, having its concavity backwards, and anastomoses, at the fourth intermetatarsal space, with the termination of the dorsalis pedis; from this results a plantar arch, which gives off, from without to within: 1, The external collateral of the little toe; 2, 3, 4, 5, the interosseous plantar (or digital) arteries of the first, second, third and fourth inter- metatarsal spaces; these arteries, at the root of the toes, bifurcate to furnish collaterals to these ns. The Fr carved tibial artery, situated on the anterior face of the interosseous ligament that unites the tibia to the peroneus, éxtends to the annular ligament of the tarsus, 7 = L 2* ¥ a at x : aa oa = ¥ nas THE ARTERIES. a where it is continued by the dorsalis pedis, which descends along the dorsum of the fout os, to gain the summit of the fourth interosseous space, ve The dorsal artery of the metatarsus (metatarsea) is almost nil in Solipeds.. Ta Man it =a ANTERIOR ASPECT OF HUMAN LEG AND FOOT. 1, Tendon of insertion of the quadriceps ex- POSTERIOR ASPECT OF HUMAN LRG, 1, Tendons of inner ham-string; 2, Ditto of tensor muscle; 2, Insertion of the ligamen- tum patell#; 3, Tibia; 4, Extensor longus digitorum; 6, Peronei; 7, Inner belly of gastrocnemius and soleus; 8, Annular ligament ; 9, Anterior tibial artery ; 10, Its recurrent branch inosculating with (2) inferior articular and (1) superior articular arteries, branches of the popliteal; 11, Internal malleolar artery; 17, External ditto, inosculating with anterior peroneal artery, 12; 13, Dorsalis pedis artery; 14, Tarsea and metatarsea; 15, Dorsalis hal- lucis artery; 16, Continuation of dorsalis pedis into sole of foot. biceps; 3, Popliteus muscle; 4, Flexor — longus digitorum ; 5, Tibialis pesticus 6, Fibula; 7, Peronei muscles; 8, Lower portion of flexor longus pollicis, er its tendon; 9, Popliteal artery, giving off articular and muscular branches; 10, An- terior tibial artery; 11, Posterior tibial — artery; 12, Relative position of tendons and artery ; terior peroneal. 13, Peroneal artery; 14, bh is directed transversely to the tarsus, fiom within to without; its terminal branchas , unite on the dorsum of the tarsus, and the arch it forms gives off the dorsal interosseous arteries of the three first spaces. These communicate above and below, in the inter- THE BRACHIAL OR AXILLARY ARTERIES. 559 metatarsal spaces, with the plantar interosseous arteries by the anterior and posterior Sagi Meo finally, at the base of the toes they bifurcate to form the collateral ries 0, toes. _ The collateral artery of the fourth space represents E the vessel described in the Horse by the name of metatarso- ; peel artery, or collateral of the cannon; it forms the in- ternal collateral dorsal of the fourth toe, and external collateral of the great toe. The dorsalis pedis, after giving off the last-named vessel, dips into the fourth space and reaches the lower surface of the foot, where it anastomoses with the internal plantar artery. Tn this list ion of its course it resembles the vessel we have named the perforating pedal in Solipeds. _ Articce V.—Antenton Aorta. (Fig. 282, 1.) This vessel, the smallest of the two trunks suc- ceeding the common aorta, is no more than 2 or 24 inches in length at the most. It leaves the pericar- dium to pass between the two layers of the medias- tinum in an oblique direction from below upwards and behind forwards, above the right auricle, below the trachea, and to the left of the anterior vena cava. Fig. 281. -_ sf ¥ ae ie, a WOT After furnishing some insignificant twigs to the pericardium and mediastinum, it divides into two branches which constitute the brachial trunks or axillary arteries. : In the Pachyderms and Carnivora, the anterior aorta does not exist, and the axillary arteries arise directly from the aortic trunk, towards the pvint from which the anterior aorta springs in other animals. ARTERIES OF SOLE OF HUMAN FOOT, 1, Under surface of os cal- cis; 2, Musculus acces- Articte VI.—Bracatat Trunks on AXILLARY Anrentes. (Fig. 282, 2, 3.) The brachial trunks, terminal branches of the anterior aorta, are distinguished into left and right. The latter is much larger than the former, because it furnishes the arteries of the head. It is also named the brachio-cephalic trunk (or arteria innomi- nata). igin.—They separate from one another at an sorius; 3, Long flexor tendons; 4, Tendon of peroneus longus; 5, Ter- mination of posterior tibial artery; 6, Internal plantar; 7, External plantar ; 8, Plantar arch giving off four digital branches, three of which are seen dividing into * collaterals for adjoining toes, acute angle, the left being a little more elevated than the right. Course and direction.—Both branches are directed forwards, between the laminw of. the anterior mediastinum and beneath the trachea; gaining the entrance to the chest, and leaving it by turning round the anterior border _ of the first rib, under the insertion of the scalenus, they become inflected _ backwards and downwards, to be placed, one to the right, the other to the left, at the internal face of the anterior limb, in the middle of the nervous branches of the brachial plexus, and continue within the arm, assuming the name of humeral artery on leaving the interstice which separates the sub- scapularis muscle from the adductor of the arm. _____ In its thoracic course, the left trunk describes a curve whose convexity is oo the right taking a rectilinear direction. ions.—In studying the relations of the brachial trunks, we recognise two principal portions: one thoracic, placed in the chest; the other axillary, 560 THE ARTERIES. situated beneath the limb. In their thoracie portion, the brachial Ac at first lying beside each other, separate slightly in front to reach the internal — face of each of the two first ribs. They are accompanied by the cardiac, pneumogastric, inferior laryngeal, and diaphragmatic nerves, and are in- cluded, as already noticed, between the two layers of the anterior iene | ee *, tinum. ‘lhe right occupies nearly the median line beneath the inferior face - of the trachea, to the left and above the anterior vena cava. The lefé slightly rises on the side of the trachea, and generally corresponds inwardly = to the thoracie duct. ty In their axillary portion, these vessels accompany the corresponding venous trunks, cross the terminal tendon of the subscapularis muscle in passing below the humeral insertion of the pectoralis magnus, and among | the branches of the brachial plexus, but embraced more particularly by the median, anterior humeral, and ulnar nerves. = Distribution.—The axillary arteries give off, on their course, eight col- — Rs, lateral branches. Four arise from the thoracic portion: three upper, the o dorsal, superior cervical, and vertebral arteries ; and an inferior, the internal ; thoracic. Two are detached at the first rib: one downwards, the other forwards; these are the external thoracic and superior cervical arteries. TWo originate from the axillary portion of the trunk and pass upwards: they are | the super- and subscapular arteries. After furnishing the latter vessel, the brachial trunk is continued by the humeral artery. Independently of all these branches, the right axillary artery gives off, . near its origin, the common trunk of the two carotid arteries, which willbe —__ studied in a separate article. a Preparation.—The subject being placed on the right side, remove the skin and the left anterior limb, in order to make the dissection at two periods. First period.—Dissect a!l the intra-thoracie portion of the left axillary artery and its collateral branches, as in figure 282, taking care to leave the inferior cervical artery (which has been cut in the figure to render the drawing more distinct) attached by its superior extremity to the middle portion of the mastoido-humeralis, which has not been disturbed. Second period.—Prepare, on the separated limb, the extra-thoracic portion of the vessel and all the arteries it furnishes, in taking as guides figures 283, 290, and 291. ss » ~ COLLATERAL BRANCHES OF THE AXILLARY ARTERIES. 1. Dorsal, Dorso-muscular or Transverse Cervical Artery. (Fig. 282, 4.) Chiefly destined to the muscles of the withers, this artery, the first given off by the brachial trunk, crosses outwardly the trachea, thoracic duct, cesophagus, great sympathetic nerve, and the long muscle of the neck, in proceeding beneath the mediastinal layer; it reaches and passes over the second intercostal space, bends slightly backwards, and places itself in the interstice which separates the angular muscle of the scapula and great — serratus muscle from the inferior branch of the ilio-spinal muscle (longis- — simus dorsi), where it separates into several divergent branches. The majority — of these ascend towards the superior border of the withers, neck, and — shoulders, by gliding between the latter muscles, the splenius, and the small anterior serratus on the one part, and the great serratus, rhomboideus, — and proper elevator of the shoulder on the other, to be distributed to those muscles and the integuments covering them. The most anterior of these branches passes between the splenius and the great complexus muscles, © parallel with the superior cervical artery, which is in front of it. and com- municates by its ramuscules with the latter vessel, as well as with the vertebral and oecipito-museular arteries, The last-named branch is some- = i i i a i rl el ial . } y . THE BRACHIAL OR AXILLARY ARTERIES, 561 times long and voluminous, and partly supplements the superior cervical, as is exemplified in the specimen which served for Fig. 282. Before leaving the thorax, the dorsal artery gives off some unimportant | ramuscules and the subcostal artery (superior intercostal of Man). This branch (Fig. 282, 5) curves backwards and, with the sympathetic chain, places itself beneath the costo-vertcbral articulations, against the long muscle of the neck, furnishing the second, third and fourth intercostal arteries and the corresponding spinal branches, and terminating at the fifth intercostal space by either forming the artery which descends into that space, in anastomosing by inosculation with a branch emanating from the first ior intercostal artery, or by expending itself in the spinal muscles. equently the second intercostal and its spinal branch come directly from the dorsal artery ; the fifth also often arises from the posterior aorta.’ On the right side, the dorsal artery always proceeds from a trunk common to it and the superior cervical artery: a circumstance sometimes observed in the left. This trunk has no relation with the cesophagus. 2. Superior Cervical, Cervico-muscular, or Deep Cervical Artery. (Fig. 282, 6.) This vessel arises in front of the preceding artery, affects the same relations in the thoracic cavity, which it leaves by passing between the two first ribs, behind the last costo-transverse articulation ;? it is then directed upwards and forwards, passing beneath the inferior branch of the ilio-spinal and great complexus muscles, courses in a flexuous manner through the space comprised between the latter muscle on one side, and the superior branch of the ilio-spinalis and cervical ligament on the other, and arrives at the second vertebra of the neck, where its terminal divisions anastomose with the branches of the occipito-muscular, vertebral, and even the dorsal, arteries. The superior cervical artery distributes in its course : 1, The first inter- costal artery and the first spinal branch ; 2, Very numerous branches which are ded in the muscles and integuments of the cervical region, as well as Gest ligament occupying the middle plane of that region ; among these branches, one longer than the others traverses the great complexus muscle to place itself between it and the splenius, and which is sometimes supplemented in great part by the dorsal artery. 3.. Vertebral Artery. (Fig. 282, 7.) Arising at an acute angle from the axillary artery at the first intercostal space, and covered at its origin by the mediastinal layer, the vertebral proceeds forward and upward, within the first rib, outside the ee ates the trachea, and the inferior cervical ganglion, and is situated at the bottom of the interstice separating the two portions of the scalenus, with the fasciculus of branches originating from the brachial plexus, which is a little above the vessel. It then passes beneath the transverse process of the seventh cervical vertebra, and traverses the series of cervical _ foramina, hidden beneath the intertransverse muscles, to anastomose in 1. For the description of these arteries, see page 524. * We have seen it escape, along with the dorsal artery, by the second intercostal ? On the right, these relations with the esophagus are not present. b i) 562 THE ARTERIES. Fig. 282. ve. MUERENoy, DISTRIBUTION OF THE ANTERIOR AORTA, 1, Anterior aorta; 2, Left axillary artery; 3, Right axillary artery; 4, Dorsal artery; 5, Subcostal artery; 6, Superior cervical artery; 7, Vertebral artery; 8, 8’, Inferior cervical artery; 9, Origin of the internal thoracic artery; 10, Origin of one of the external or intercostal branches of this artery; 11, One of its inferior ramuscules; 12, External thoracic artery ; 13, Origin of the super- scapular artery; 14, Primitive, or common carotid artery ; 14’, Accessory thyroid artery; 14” Thyro-laryngeal artery ; 15, Atloido-muscular artery; 16, Occipito- muscular artery; 17, Posterior aorta.—A, Pulmonary aorta; B, Trachea; ¢, Eso- phagus; D, Cervical ligament; &, Superior branch of the ilio-spinal muscle; FP, Inferior branch of the same; G, Great complexus muscle; H, Splenius muscle; I, 1, Originating aponeurosis of the splenius and the small anterior serratus muscles ; K, Section of the great oblique muscle of the head ; L, Great posterior rectus muscle of the head; M, Great anterior ditto; N, Sterno-maxillaris muscle; 0, P, Great pectoral and sterno-prescapularis muscles turned downwards. THE BRACHIAL OR AXILLARY ARTERIES. 568 full canal with the retrograde branch of the occipital artery, at the atlo-axoid articulation, underneath the great oblique muscle of the head. Tn its track, it detaches at each intervertebral space numerous branches, which may be divided into inferior, superior, external, and internal. The first chiefly pass to the scalenus, longus colli, and the great anterior rectus muscle of the head. The second, which are incomparably larger and more numerous than all the others, are destined to the two complex muscles, the transverse-spinous (semispinalis) muscles of the neck, and to the ilio-spinal muscle; they anastomose with the divisions of the superior cervical and oecipito-muscular arteries. The external branches, are very small, and pass to the intertransverse muscles. The internal branches enter the inter- vertebral foramina to join the middle spinal artery. 4. Internal Thoracic, or Internal Mammary Artery. (Fig. 282, 9.) The internal thoracic artery emerges from the brachial trunk at the first rib, and immediately descends along the inner face of that bone to the sternum,remaining covered by the pleura. It then bends backwards, passes under the triangular muscle and above the sternal cartilages, which it crosses near the chondro-sternal articulation, and reaches the base of the i appendix, where it ends in two branches: one abdominal, the other thoracic, and which have been named the anterior abdominal and asternal - arteries. Tn its course, the internal thoracic artery sends off collateral branches which may be distinguished into superior, inferior, and external. The superior are always very slender, and proceed to the pericardium and mediastinum. The inferior (Fig. 282, 11) are very large, and traverse the intercostal spaces to enter the pectoral muscles, where they meet the ramifi- _ cations of the external thoracic artery. The external branches (Fig. 282, 10) follow the intercostal spaces; each generally divides into two branches, which finally anastomose by inosculation with the terminal divisions of the first seven intercostal arteries. Terminal branches of the internal thoracic artery.—1. Anterior ab- dominal artery.—This vessel separates from the asternal artery at an acute angle, and passes directly backward to escape from the chest by coursing beneath the xiphoid appendix; it then places itself on the superior face of the rectus muscle of the abdomen, which it enters, after detaching lateral branches to the abdominal walls, and anastomoses by its terminal ramifica- tions with the posterior abdominal artery. 2. Asternal artery.—This vessel glides within the cartilaginous circle - formed by the false ribs, in crossing the digitations of the transverse muscle of the abdomen, and terminates at the thirteenth intercostal space, in which it ascends to anastomose with the corresponding intercostal artery. It supplies in its track: intercostal branches, which comport themselves. like the analogous branches of the internal thoracic artery; fine diaphragmatic twigs; and abdominal divisions, which particularly ramify in the tranverse 5. External or Inferior Thoracic, or External Mammary Artery. (Fig. 282, 12.) - Principally destined to the deep pectoral muscles, this artery commences at an acute angle in front of, but close to, the preceding, turns the anterior _ border of the first rib, and then passes back against the internal face of the great pectoral and sterno-prescapular muscles, in which are SE eres its o 564 THE ARTERIES. collateral and terminal divisions. It gives off a fine branch which accom- — panies the spur vein, and ramifies in the panniculus carnosus. rg This artery sometimes rises from the suprasternal vessel; its volume — is subject to great variations, and we have seen it entirely absent. 6. Inferior Cervical, or Trachelo-muscular Artery. (Fig. 282, 8, 8'.) Originating opposite the two preceding vessels, sometimes near the external, and at other times near the internal mammary arteries, this vessel is at first situated in the gulf between the jugulars, within the sterno-pre- scapular muscle, and above the glands at the entrance to the chest ; it divides after a short course into two branches, which separate at a very acute angle. One of these, the superior (ascending cervical of Man), rises between the mastoido-humeralis and subscapulo-hyoideus muscles, to which it is dis- tributed, as well as to the glands at the point of the shoulder, and the sterno- prescapularis and triangularis scapule muscles, : The inferior branch (thoracica acromialis of Man) descends in the in- terstice comprised between the mastoido-humeralis and the sterno-humeralis (pectoralis parvus) muscles, accompanying the cephalic vein; it is distri- buted to these two muscles, the sterno-aponeuroticus (pectoralis transversus), and the sterno-prescapularis. 7. Superscapular, or Superior Scapular Artery. (Fig. 282, 18.) A small and slightly tortuous vessel, which arises from the axillary artery, a little before it reaches the tendon of the subscapularis muscle. — It is directed upwards, and enters the space included between that muscle and the super- (antea-) spinatus, after sending off some divisions to the sterno- prescapularis muscle. Its terminal branches are expanded in the inferior extremity of the super- and subspinati muscles, the tendon of the coraco- radialis, and in the articulation of the shoulder. 8. Inferior, or Subscapular Artery. (Fig. 347.) This artery is remarkable for its considerable volume; it arises at a right angle from the axillary artery, at the space separating the phage ei from the adductor of the arm. Its origin indicates the limit artificially fixed between the brachial trunk and the humeral artery. It is seen to proceed upwards and backwards in this interstice, within the large extensor of the fore-arm, until near the dorsal angle of the scapula, where it terminates. It gives off on its track : ‘ 1. An artery which, following the inferior border of the great dorsal muscle, ascends to its inner face, throwing off twigs into the substance of the muscle as well as into the panniculus carnosus. ‘ 2. The scapulo-humeral, or posterior circumflex artery of the shoulder, which passes from within that articulation, beneath the great extensor muscle of the shoulder, to reach its external face; after giving off some collateral — branches, it arrives, with the circumflex nerves, underneath the abductors of the arm, where it breaks up, like its satellite nerve, into several divergent branches destined to the three muscles above named, the oblique flexor and — short extensor of the fore-arm, and to the mastoido-humeralis and panniculus carnosus. i THE BRACHIAL OR AXILLARY ARTERIES, 565 8. Muscular branches, which escape at intervals during the course of the vessel, and are sent forwards and backwards. The anterior pass either to the internal or external side of the scapula, or to both sides of that bone, whose posterior border they embrace in their bifurcation. The internal divisions creep in the fissures on the deep face of the bone, throwing their ramuscules into the subscapularis muscle, and even reaching the super- (antea-) spinatus, as well as the insertion of the angularis and great serratus muscles. The external divisions traverse the large extensor of the fore-arm, to be dis- tributed to the super- and subspinati and the abductor muscles of the arm, one furnishing the nutrient artery of the scapula. The posterior branches supply the abductor of the arm, and the large extensor of the fore-arm. HUMERAL ARTERY, OR TERMINAL ARTERY OF THE BRACHIAL TRUNK. (Fig. 347, a.) Course.—This, a continuation of the axillary artery, which changes its name after giving off the subscapular branch, at first describes a slight curve forwards to descend almost vertically within the thoracic limb by crossing obliquely the direction of the humerus, and terminates above the inferior extremity of that bone by two branches which constitute the anterior and a radial arteries. . ions.—In its course, the humeral artery corresponds: in front, to the median or ulno-plantar nerve, and to the posterior border of the coraco- humeralis muscle, which it closely follows; behind, to the vein of the arm, and through it to the ulnar nerve ; outwardly, to the common tendon of the great dorsal muscle and the adductor muscle of the arm, to the middle extensor of the fore-arm, and to the humerus; inwardly, to the sheath of the coraco-radialis muscle, which separates the pectoralis magnus from the of the arm, and in which this vessel is inclosed, in common with its satellite vein, the lymphatic glands and vessels of the arm, as well as with the nerves of the fore-limb. Collateral branches.—Among these may be distinguished four, which merit particular mention. They are the prehumeral, external and internal collateral arteries of the elbow, and the principal artery of the coraco-radialis muscle. We need only indicate, besides these, several irregular ramuscules which go to the latter muscle, to the coraco-humeralis, and to the middle extensor of the fore-arm. : 1. Prehumeral, or anterior circumflex artery of the shoulder.—This arises at a right angle, is directed forward, passes between the two branches of the coraco-humeralis, turns round the anterior face of the humerus, beneath the bicipital groove, and terminates in the mastoido-humeralis — muscle. During-its progess it gives off branches to the scapulo-brachial and biceps muscles, as well as to the articulation of the shoulder. Among the articular ramifications, there is one which ascends outwardly on the tendon of the subspinatus, and whose ultimate divisions anastomose with the ramuscules of the posterior circumflex artery. 2. Deep humeral, or external collateral artery of the elbow.—A very large branch which emerges from the humeral trunk, by forming with that artery an almost right angle at the common terminal tendon of the great dorsal muscle and the adductor of the arm. After a very short course, it divides into two principal branches; one of these sends its ramuscules into the body of the large extensor muscle; the other passes under that muscle in 566 THE ARTERIES. turning round the oblique flexor of the fore-arm, along with the radial nerve, and reaching beneath the short extensor, to descend, still with its = satellite nerve, in front of the articulation of the elbow, where this branch = anastomoses with the anterior radial artery; it supplies all the oleeranian = muscles, except the long extensor, as well as the oblique flexor of the fore- arm and the anterior extensor of the metacarpus. : 3. Epicondyloid, internal collateral of the elbow, or ulnar artery.— Smaller than the external collateral, this artery arises at the nutrient foramen of the humerus, and proceeds backwards on the internal face of that bone, to pass beneath the long extensor of the fore-arm, by following in — a more or less flexous manner the inferior border of the middle extensor; it then descends, at first behind the epicondyle, then on the fore-arm, which — it passes along for its whole length, underneath the aponeurotic sheath of this region, between the oblique and the external flexor of the metacarpus, accompanied by the ulnar vein and nerve of the same name, and the tendon of the ulnar portion of the perforans muscle. Arriving near the carpus, this long branch anastomoses by inosculation with a branch from the posterior radial artery. In its antibrachial course, this artery only gives off very attenuated branches, whose study is of little importance. But before attaining the fore-arm, it furnishes: 1, The nutrient artery of the humerus; 2, Articular ramuscules ; 3, More or less voluminous muscular branches, particularly for the long extensor of the fore-arm, the middle extensor, and the sterno- aponeuroticus : those which arrive in the latter muscle traverse it only to become subcutaneous alternately ; one of them accompanies the principal superficial vein of the fore-arm, and sends ramuscules into the bend of the elbow. Regular in their distribution, these different arteries present numerous varieties of origin, among which it is difficult to distinguish the most constant disposition, The last-mentioned vessel and the nutrient artery of the humerus, often emanate directly from the humeral trunk. 4. Principal artery of the biceps, or coraco-radialis artery. —This originates a little below or above the preceding ; opposite to, or in front of it, it usually divides into two branches: one ascending, the other descending, which enter the substance of the muscle. bh 1. Anterior Radial Artery. (Fig. 848, a.) The anterior radial artery,’ the smallest of the two terminal branches of the humeral, separates itself at an acute angle from the posterior artery, above the articular condyle of the humerus, It descends on the anterior face of the ulnar articulation, passing beneath the inferior extremity of the flexor muscles of the fore-arm and the superior extremity of the principal extensor of the metacarpus, where it meets the radial nerve; in com with this nerve it extends on the anterior face of the radius, below the ~ anterior extensor muscle of the phalanges, to the knee, where it becomes very thin and breaks up into several ramuscules, which are continued on the capsular ligament of the carpal articulations, after anastomosing on the inner side with the divisions of a branch furnished by the posterior radial artery, and on the outside with the ramifications from the interosseous artery of the fore-arm. ‘ ‘In Man this artery is absent, or rather it is represented by an insignificant muscular twig. « a a es ee ee ' THE BRACHIAL OR AXILLARY ARTERIES. 567 These terminal ramuscules of the anterior radial artery are distributed to the carpal articulation, or the sheaths of the extensor tendons, and com- municate with the dorsal interosseous metacarpal arteries. The collateral branches given off by this artery are very numerous, the majority of them being detached from the superior portion of the vessel _ near the elbow; they are intended to supply that articulation, but more ially the muscular masses lying in its neighbourhood, or covering it. Such is the usual disposition of the anterior radial artery; though it is liable to numerous variations: principally in the manner in which it comports itself with the interosseous artery of the fore-arm, which may even supple- ment it for the whole of the middle and lower part of its course. This will be noted in describing the next artery. 2. Posterior Radial Artery. (Figs. 283, 1; 347, 8.) This vessel, in its volume and direction, represents the continuation of the humeral artery. It descends, along with the ulno-plantar nerve, on the internal ligament of the humero-radial articulation, behind the terminal extremity of the coraco-radialis; then under the internal flexor of the meta- carpus, its satellite muscle. Arriving at the inferior extremity of the radius, it divides into two terminal branches; which are, the common trunk of the interosseous metacarpal arteries and the collateral artery of the cannon. The following are the principal collateral branches furnished by the ior radial artery : 1. At the superior extremity of the radius, articular ramuscules which anastomose with analogous branches from the epicondyloid artery. 2. A little lower, large divisions destined for the muscles of the posterior antibrachial region, some of them arising from the next artery. 8. The interosseous artery of the fore-arm, a considerable vessel which originates at the same point as the preceding—the radio-ulnar arch, and which crosses this from within to without, after traversing the posterior face of the radius, beneath the perforans muscle, to descend along the lateral extensor muscle of the phalanges, in the channel formed outwardly by the union of the two bones of the fore-arm. This interosseous artery furnishes, immediately after its exit from the radio-ulnar arch, several branches to the articulation of the elbow and the antibrachial muscles. At its terminal extremity it usually divides into a number of branches, the majority of which join the branches sent to the carpus by the anterior radial artery. It is rare that it does show some fine anastomoses with one of the divisions of the latter artery in front of, or outside the articulation of the elbow ; some- times it directly joins that vessel; and I have seen it, on the contrary, receive the anterior radial artery, which it in part supplanted. 4, Several muscular and musculo-cutaneous ramuscules without any fixed arrangement, arising from different points of the course of the parent artery, __ below the preceding divisions. 5. A deep branch, also liable to very numerous variations, having its origin at the radial insertion of the perforatus muscle, descending on the agra face of the radius, chiefly destined to the carpus, and remarkable the anastomoses that its internal divisions contract with the anterior radial artery, and for those which occasionally unite its external ramifications to the ultimate branches of the interosseous artery of the fore-arm or the epicondyloid artery (Fig. 283, 2). & 568 ‘THE ARTERIES. 1, Firat Terminal Branch of the Posterior Radial Artery, or Common Trunk of the Interosseous _ Arteries,’ (Fig. 283, 5.) This arterial branch separates at a very acute angle from the collateral artery of the cannon. It descends inside and behind the carpus, accompanied by the prin- cipal subcutaneous vein of the limb, and with it is included underneath a superficial fascia, which maintains them in a channel hollowed on the external face of the carpal fibrous sheath. It thus arrives within the head of the inner metacarpal bone, where it is inflected to the outer side by crossing the superior extremity of the sus- pensory ligament, and between it and the metacarpal liga- ‘al ment the latter furnishes to the perforans tendon; it amas- tomoses by inosculation with a descending branch which emanates from the superficial arch that, above the carpus q unites the epicondyloid or ulnar artery to the origin of the collateral artery of the cannon (Fig. 283, 6). loop-like anastomosis thus formed by the radio-palmar artery, exactly corresponds to the deep palmar arch of pentadactylous animals, particularly to that of Man. We propose to name it also the subcarpal arch, by reason of the position it occupies in regard to the carpus, reser- — ving the appellation of supracarpal arch for the super- Jicial palmar arch, which is represented by the anastomosis established between the collateral artery of the cannon and the epicondyloid artery. Four principal branches emanate from this subcarpal arch; these are the metacarpal interosseous arteries, dis- tinguished into posterior or palmar, and anterior or dorsal. a, The posterior interosseous arise, one on the right, the other on the left, at the head of the lateral meta- carpal bones, each descending on its own side, and in a — flexuous manner, along these rudimentary bones, in the angular groove formed by their inner face and the pos- terior face of the principal metacarpal bone, terminating = The muscles and tendons have been removed, only a small portion of the perforans tendon being left; the os pedis has been chiselled away on its plantar face to expose the semilunar anastomosis. 1, Posterior radial artery; 2, Innominate carpal branch; 3, Supra- carpal arch; 4, Epicondyloid (ulnar) artery; 5, Radio-palmar artery, or common trunk of the interosseous metacarpal arteries ; 6, Subcarpal arch; 7, 7, Posterior interosseous aS arteries ; 7', 7', Anterior interosseous metacarpal arteries; 8, 8, Their origin; ARTERIES OF THE 9, Collateral artery of the cannon; 10, Its communicating branch FORE-FOOT, SEEN with the interosseous arteries; 11, 11, Digital arteries; 12, Semi- FROM BEHIND, lunar anastomosis in the os pedis; 13, Emergent branches of this anastomosis; 14, Plantar ungueal artery, forming this anastomotic — arch; 15, Origin of the preplantar ungueal artery; 16, Origin of the plantar-cushion artery; 17, Origin of the auterior branch of the coronary circle; 18, Posterior branch of the same. 1 This vessel corresponds to the radio-palmar wy of Man, by which name it is sometimes designated. Rigot has improperly named it the deep plantar artery. et at os tea atl” en lean | nn a i ig he i ee Di ti a i ee) es Fe ‘A ._" 7 — - ‘ j - ) ) THE BRACHIAL OR AXILLARY ARTERIES. 569 at the inferior extremity of the lateral bones by anastomosing in full eanal with a branch of the collateral of the cannon. They furnish some ramifications to the suspensory ligament which covers them, and several tendinous and cellulo-cutaneous twigs; one supplies the medullary artery _of the principal cannon bone (Fig. 283, 7). b. The anterior interosseous arteries arise from nearly the same point as the ogee one outwards, the other inwards, turning back round the head of the lateral metacarpals to place themselves in the groove which separates _ these from the principal metacarpal bone, on their external or dorsal face, after having thrown off several anastomosing ramuscules which communicate between the two arteries in front of the upper extremity of the median meta- carpal bone, or with the terminal branches of the anterior radial and the interosseous arteries of the fore-arm. By their terminal extremity, these two arteries anastomose with a branch of the collateral of the cannon—that which receives the posterior interosseous arteries (Fig. 282, 7’, 8). The dorsal interosseous arteries, although much finer than the palmar (in Solipeds these arteries are quite rudimentary), nevertheless furnish collateral divisions destined for the anterior tendons of the metacarpus, the periosteum, the connective tissue, and the skin. They often communicate with the ior arteries by deep branches, which cross the intermetacarpal ts. Variations.—The existence of the interosseous metacarpal arteries, their position, and their anastomoses with the inferior extremity of the collateral of the cannon, are constant; though this is not the case with regard to their origin, or the source from which they arise. In the typical description we have given, we have considered them all as being furnished by the radio- palmar artery; but it is necessary to add that one of the four, the external dorsal, often comes directly from the arterial branch that, from the supra- arch, descends along the carpus to concur in forming the subcarpal arch, by anastomosing with the radio-palmar, or rather with a branch of the interosseous of the fore-arm, It is also necessary to add that these meta- arteries sometimes arise together from one large branch furnished by the collateral of the cannon, at the superior extremity of the metacarpus, and which receives the now rudimentary radio-palmar artery, as well as that given off by the supracarpal arch ; so that we may have two superposed supracarpal arches. We have met other anomalies which need not be noticed here, as they are without interest. 2. Second Terminal Branch of the Posterior Radial, or Collateral Artery of the Cannon.’ (Fig. 283, 9.) The collateral artery of the cannon continues, in its volume and direction, the posterior radial artery. It passes, with the flexor tendons, under the arch, and descends on the inner side of these tendons, accompanied by the internal plantar nerve, to above the fetlock and near the great sesamoid bones, where it bifurcates into the digital arteries. Collateral branches.—We observe : 1. Near the origin of the artery, and very often from the posterior radial artery itself, a branch which anastomoses above the pisiform bone with the epicondyloid artery, forming an arch whose convexity is inferior (Fig. 283, 3), and which has been already noticed as the supracarpal or superficial palmar ' This artery, the eal plantar of Rigot, represents one of the metacarpal palmar branches furnished by the superficial palmar arch in Man and other pentadactylous an. 570 THE ARTERIES. arch, in contradistinction to the subcarpal or deep palmar arch, the source of the interosseous arteries of the metacarpus. is ramification furnishes one or more muscular twigs that usually anastomose with the other branches of the posterior radial artery ; and an inferior division,’ which descends in the carpal arch, within the pisiform bone, to the superior extremity of the metacarpus, where it inosculates with the radio-palmar artery, after detach- ing several carpal ramuscules, the principal of which turns round the inferior border of the pisiform bone. . 2. On its course, numerous and fine synovial tendinous and cutaneous divisions. ; 3. A trunk springing from the terminal extremity of the vessel, between the two digital arteries, sometimes even from one of these, which is placed at the posterior face of the principal metacarpal bone, within the two branches of the suspensory ligament, and, passing upwards, soon divides into two branches ; these anastomose by inosculation with the posterior inter- — osseous arteries of the metacarpus, after giving off on each side two other ramuscules which wind round the borders of the middle me receiving the dorsal interosseous arteries, and ramify in front of the fetlock, _ on the anterior face of the cannon bone, and in the texture of the ca ligament of the metacarpo-phalangeal articulation (Fig. 283, 10). Terminal branches.—These are, as we said, the digital arteries, whose dis- position almost exactly repeats that of these vessels in the posterior limb, and which have been described at page 551. DIFFERENTIAL CHARACTERS IN THE AXILLARY ARTERIES OF OTHER THAN SOLIPED ANIMALS, 1. Axillary Arteries of Ruminants. These vessels comport themselves in their origin, course, and relations, as in Solipeds. The special characters they present in their distribution are as follows: 1. Dorsal artery.—This arises from a trunk common to it and tle vertebral artery, and usually leaves the thorax by passing above the first costo-vertebral articulation. Its subcostal branch proceeds directly from the above-named trunk, 2. Superior cervical artery.—This is absent, and is replaced by a branch of the dorsal artery, but particularly by the superior muscular divisions of the vertebral A 3. Vertebral artery—Extremely voluminous, and terminates in the muscles of the neck, after passing through the foramen of the axis; it is remarkable for the considerable size of its spinal branches. 4. Inferior cervical, internal and external thoracic arteries.—These do not present anything worthy of special consideration, except that the last is very voluminous in the Ox and very slender in the Sheep, and supplies the satellite arterial branch of the cephalic vein, which, in Solipeds, arises from the inferior cervical artery. 5. Superscapular artery.—This vessel appears to us to be absent in the Sheep, and its place supplied by the divisions of the inferior cervical artery. — 6. Subscapular artery.—The scapulo-humeral branch gives oft the majority of the branches destined to the posterior brachial muscles. 7. Humeral artery—The muscular arteries are of small size, particularly the deep humeral, which is largely replaced by the scapulo-liumeral branch, 8. Anterior radial artery—This comports itself similarly to that of the Horse, and is liable to as frequent anomalies. 9. Posterior radial artery—This artery follows the same course as in Solipeds ; onl instead of furnishing the radio-palmar artery near the carpus, at the point where it becomes the collateral artery of the cannon, it gives off that vessel much higher, and near ~ the upper third or middle of the fore-arm. Its interosseous branch, lodged in the deep channel on the outside of the bones of this region, where the radius and ulna join, is” separated into two branches near the inferior extremity of that groove. The anterior of these ramifies on the dorsal face of the carpus, and anastomoses with the divisions of the 1 Analogous to the radio-ulnar artery of Man. “ ae - i r * = a THE BRACHIAL OR AXILLARY ARTERIES. 571 anterior radial artery; the ipetester traverses the inferior radio-ulnar arch, to distribute of its branches the majorit: ind the carpal articulations. ag r artery.—Arising, as we have already seen, from the posterior artery, towards the upper third of the fore-arm, this branch descends to the r extremity of the metucarpus in following, as in the Horse, a superficial course, ends in four metacarpal interosseous arteries: three posterior or palmar, and one auterior or dorsal. ‘The posterior interosseous arteries are bea irregular and inconstant in their tion; they communicate with each other by several branches, and anastomose, inferiorly, either with the lateral digital arteries, the collateral of the cannon, or, as is most commonly the case, with a branch of the latter vessel. These interosseous are distinguished into external, middle, and internal; the first two are comprised between the ior face of the metacarpus and the suspensory ligament; the third, gee at the inner border of that ligament, is more considerable than the others, and by yolume and direction represents the continuation of the radio-palmar artery. The anterior interosseous artery passes through the foramen at the superior extremity of the , metacarpus, and arriving at the dorsal face of the bone, it bifurcates, its ascending reaching the capsular ligament of the carpal articulations, where it anastomoses with the divisions of the anterior radial and interosseous arteries of the fore-arm; the descending is lodged in the anterior groove of the metacarpal bone, and joins a perforating branch of the collateral artery of the cannon—a branch which crosses the foramen i towards the inferior extremity of the bony diaphysis. If it is desired to ascertain signification of these interosseous arteries in their relation to the elements composing the foot of Ruminants, we readily recognise: in the posterior median artery, the interosseous palmar of the two great digits; in the posterior lateral arteries, the interosseous ] in’ , intermediates to these middle digits, and the rudimentary lateral 7 digits represented by the ergots or dew claws ; and in the single anterior artery, the dorsal ____ interosseous of the two great digits. We may even prove, by a more minute examination, the existence of dorsal interosseous arteries corresponding to the lateral palmar inter- osseous vessels. 11. Collateral artery of the cannon.—This artery follows the same track as in the Horse, as far as tle lower third or fourth of the metacarpus. Arrived at this point, it abandons, as in the + a branch whose divisions communicate with the interosseous arteries, and dat by the digital arteries, three in number: a middle and two "a Be teeonicnting branch with the metacarpal interosseous arteries very often arises the internal digital artery. It is insinuated between the divisions of the suspensory ligament, and ascends on the posterior face of the metacarpus, breaking up into a number of branches which nearly the ted arteries, or even the lateral digital, in affecting a variable and plicated disposition which it is needless to notice here, One of these branches—a true perforating artery, traverses the inferior extremity of the cannon bone, and ascends in its anterior groove to join the anterior interosseous artery, after detaching ramuscules to the opt articulation. b. The digital artery represents, by its dimensions, the continuation of the collateral of the cannon, and is a very voluminous vessel. It is at first inflected backwards and outwards to be placed on the posterior face of the perforatus tendon; then it descends into the interdigital space by passing behind the great sesamoid sheath, beneath the ligament uniting the two claws. Reaching the inferior extremity of the first phalanx, it divides into two ungueal arteries, one for each digit, which are inflected pass beneath the internal ligament common to the two interphalangeal articu- lations, and enter by the foramen pierced at the inner side of the pyramidal eminence into the internal sinus of the third phalanx, where each ramifies in the same mauner as the plantar ungueal arteries of the Horse. Several collateral branches, remarkable for the richness of their arborisations, escape from this median artery of the digits and its terminal divisions. The most important of these are: 1, At the middle of the first phalanx, two short transverse branches—a right i ho and going from the median digital arte _ to the lateral arteries of the digits ; tne at the same point, a single artery which _—— — shat iid 2 5 g branch of ig pentoenting artery which crosses the inferior extremity of the ; 8, A doub.e branch analogous to the artery of the plantar cushion of the Horse, having its origin at the tepmtnat axtrenslt the ungueal artery, cither on one side or both, and communicating, by a trausverse branch, 572 THE ARTERIES. with its homologue; it is directed backward and downward on the bulb of the h where it forms an anastomotic arch with the lateral digital artery; from the conve: of this arch, which is turned downwards, there escape a large number of reticulatir ramuscules, destined for the keratogenous membrane and the plantar cushion. : ec. The lateral digital arteries are distinguished into internal and external. The el has its origin at the bend formed by the collateral of the cannon, when that vessel i inflected on the posterior face of the perforatus tendon to become the median artery, most frequently in common with the branch whose divisions join the ) rpa 4 interosseous arteries. The second commences a little further off, after having io branch from either this communicatin ing artery, or from the external interosseous cori os it is not rare to see it entirely formed by one of these branches, or by the two “the ex ; Whatever may be their point of origin, the lateral digital arteries descend on €x- ceutric side of the digits, without the flexor tendons, and terminate in by inosculation with the artery of the plantar cushion. Among the collateral branches» 4 emanating from these arteries, there ouglit to be distinguished that which tothe ergot, and the transverse branch thrown across between each, as well as the nedian +a digital artery.' +e 2. Axillary Arteries of the Pig. ae Both spring separately from the arch of the sorta; consequently, there is no anterior my aorta. The right urtery, or brachio-cephalic trunk, first arises; the left comes inner . e after. : a. The brachio-cephalic trunk is directed forwards, under the inferior face of the trachea, and leaves the thorax to reach the inner face of the anterior limb, as in other : It furnishes successively :— . 1, At the first rib, and below, the two carotid arteries, rising singly from nearly the same point. , 2. Mirectly opposite to these vessels, a trunk remarkable for the oon the sa “< attending its mode of distribution; it is directed upwards and backwards, on the side __ of the trachea and longus colli, crosses the interval between the second and third ribs, and elevates itself into the deep cervical muscles, to terminate in the a of the of the neck. It evidently represents the deep or superior cervical art Near its 0 a it gives off the vertebral artery, whose mode of termination is exactly t e same a in Horse. Beyond this, it detaches the dorsal artery, which ascends into the museles of the withers, after passing into the first intercostal space. Lastly, it eet ye before leaving the, thorax, the subcostal or superior intercostal artery, placed across the superior — extremities of the third, fourth, and fifth ribs. 3. Always within, but a little more forward than the first rib, a voluminous inferior cervical artery, divided into several ascending branches; and the two thoracic arteries, — which offer nothing icular for description. 4, Without the thorax, on the internal face of the scapulo-humeral articulation humeral or subscapular arteries ; the first, less voluminous than the other, presents, : anil its origin to the distribution of its branches in the foot, a disposition cnet resembling that observed in this vessel in Ruminants; the second courses upwards in — the space between the subscapular muscle and the teres major, and soon divides into two terminal branches, one of which continues the primitive track of the vessel, while — the other passes beneath the subsca ey mig muscle to carry its ramifications into the | antero-external muscles of the shoulder, furnishing in its course: 1, The great dorsal — artery, throwing a ie of its ramifications into the olecranian muscles: 2, A volu- — minous branch which provides the greater number of the divisions given off, in the Horse, by the deep humeral and prehumeral arteries; 3, Two articular branches, one of which closely represents the Pepesger, 08 artery oe b. The left brachial trunk only differs from “the right in the disposition of pond a superior cervical, dorsal, and vertebral aiteries, which have distinct origins; last are very close to each other, and the first furnishes the subcostal branch. § Z 8. Axillary Arteries of Carnivora. These arise separately from the sige tie the arch of the aorta, as in the furnish successively, apart from the carotids, special branches of the brachi trunk :— 1. A voluminous trunk, the common origin of the dorsal, superior cervical, and a 1 In several instances, we have seen the lateral digital arteries stop | at this transverse anastomosis, which then received them entirely. THE BRACHIAL OR AXILLARY ARTERIES. 578 costal or superior intercostal arteries; the first passes between the two anterior ribs; the od in front of the first; the third across the internal face of the first, second, and third ribs near their cartilages, where it emits ascending and descending intercostal the occipital artery; it supplements, in very great part, the superior cervical, whose Silaass fi Giuinutive, and wh -s8 ~ seapular « , Which appears to be absent. 6. ie sdtoop extremity of the radius into two terminal branches; these are the ulnar and radial arteries. It detaches on its course collateral branches, analogous to those which have been described for Solipeds, and among which is a thin vessel, a vestige of the anterior radial artery, that passes beneath the terminal extremity of the biceps to supply the muscles covering, anteriorly, the articulation of the elbow. Ulnar artery— Much smaller than the radial, this vessel transmits, near its origin, the interosseous artery, which sometimes proceeds directly from the humeral artery, and whose calibre always exceeds, in animals, that of the ulnar artery. The latter is directed obliquely outwards and downwards, passing under the perforans, and gains the internal face of the anterior ulnur or oblique flexor of the metacarpus, where it lies beside the ulnar nerve, to descend with it inside the unciform bone, and join the posterior interosseous artery, or one of its terminal branches. On its track it gives off a number of muscular or cutaneous branches, several of which anastomose with the internal collateral artery of the elbow, as well as with divisions of the radial artery. Interosseous artery.—This artery is placed between the cubitus and radius, under- neath the square pronator, and is prolonged to the lower third of the fore-arm, where it separates into two branches—tlhe anterior and posterior interosseous arteries, after ing on its way several branches, mostly anterior, which enter the antibrachial museles by traversing the space comprised between the two bones of the fore-arm, the incipal escaping by the radio-ulnar arch. The anterior interosseous artery, after passing between the radius and ulna, descends on the anterior face of the carpus, where its divisions meet, inwardly, the collateral ramuscules of the radio-palmar artery, and outwardly, the arborisutions of a branch from the posterior inteross.ous artery, forming with these vessels a wide-meshed plexus, from which definitively proceed several filaments that join the ‘dorsal interosseous arteries. The posterior interosseous artery may be regarded, by its volume and direction, as the continuation of the interosseous trunk. After emerging from beneath the square pronator, it detaches an internal flexuous branch anastomosing with the radio-palmar artery, then several musculo-cutaneous branches; after which it is placed within the pisiform bone, where it divides into two branches, after receiving the ulnar artery. The smallest of these branches anastomoses by inosculation with the superficial palmar arch ; the other, larger and deeper-seated, is carried in front of the flexor tendons, beneath the a) is covering the interosseous muscles, across the superior extremity of these, and so forming the deep palmar arch, which unites wit! a thin filament from the radio-palmar artery. This arch supplies, with some ramuscules destined to the muscles of the hand (or paw), eight interosscous metacarpal arteries: four posterior or palmar, which are united by their inferior extremity with the colluterals of the digits, after giving several divisions to the muscles of the hand; and four anterior or dorsal, traversing the superior extremity of the intermetacarpal spaces, like the perforating arteries in Man, joining the anterior interosseous branches of the fore-arm, and descending afterwards into the intermetacarpal — to unite with the collatera] arteries of the digits at the metacarpo-phalangeal articulations. Radial artery: the™posterior radial of the other animals. Lying alongside the long flexor of the thumb and the perforans muscle, this artery follows the inner face of the ee muscle, and enrving outwards to be united to a branch from the pretence antibrachial interosseous artery, forms the superficial palmar arcade, from which escape 574 Fig. 284, ARTERIES OF THE HUMAN FORE-ARM, 1, Lower part of biceps; 2, Inner condyle of humerus ; 3, Deep portion of pronator radii teres; 4, Supinator longus; 5, Flexor longus pollicis; 6, Pronator quad- ratus; 7, Flexor profundus digitorum; 8, Flexor carpi ulnaris; 9, Annular liga- ment; 10, Brachial artery ; 11, Anastomotica longus magna, inosculating above with the inferior profunda, and below with the anterior ulnar recurrent ; 12, Radial artery ; 13, Radial recurrent inosculating with the supe- rior profunda; 14, Super- ficialis vole; 15, Ulnar ar- tery ; 16, Superficial palmar arch, giving off digital branches to three fingers and a half; 17, Magna pollicis and radialis indicis ; 20, Posterior interosseous. THE ARTERIES, four branches—the palmar or collateral of the digits, These are at first situated between the perforatus and perforans tendons, and rach the superior extremity of the interdigital spaces, where they receive the meta r. interosseous arteries, and comport themselves in the fol- — lowing manner: the internal goes to the thumb; the second—counting from within outwards—gains the con- centric sidé of the index; the third, the divides into two branches which lie alongside the great digits; the last goes to the external digit. COMPARISON OF THE AXILLARY ARTERIES IN MAN WITH THOSE OF ANIMALS. The arteries of the thoracic limbs and head arise se rately from the arch of the aorta; consequently, in Man there is no anterior aorta. : . The vessel of the limb that represents the axillary of animals is here resolved into two portions: the subclavian artery and axillary artery. The sUBCLAVIAN ARTERY has not the same origin on both sides; on the right it arises from the aorta bya trunk ~ common to it and the carotid of that side—tlie brachio- = cephalic trunk (arteria innominata); while the left is detached separately from the most distant part of the aortic arch. The subclavian vessels extend to the in- ferior border of the clavicles, and furnish seven important collateral branches, which are present in the domesticated ~ animals. They are :— 1. The vertebral artery, situated in the vertebral fora- mina of the cervical vertebra, as far as the axis; there it anastomoses, as in Solipeds, with a branch of the — enters the spinal canal by the foramen magnum, unites with its fellow at the lower border of the pons Varolii to form the basilar artery which, in the Horse, comes from the cerebro-spinal artery of the occipital. 2. The inferior thyroid, whose origin and some branches we find in the ascending branch (ascending cervical) of the inferior cervical artery in the Horse. 3. The internal mammary artery divides into two branches at the xiphoid appendix of the sternum. — 4. The superior intercostal artery, whose anal we see in Solipeds, in the subcostal branch of the do: 5. The superscapular artery, present in all animals” and disposed in tlie same manner. t 6. The transverse cervical (transversa colli), represented by the extra-thoracie branches of the dorsal artery. 7. The deep cervical (cervicalis profunda) corresponds ‘to the superior cervical in the Horse. The AXILLARY ARTERY, or extra-thoracie portion of the subclavian trunk, extends to the external border of the pectoral muscle, where it is continued by the humeral artery. The axillary gives off: the thoracica a resembling the descending branch of the inferior cervi artery of large quadrupeds; the external mammary ; sub- scapular ; and posterior and anterior circumflex, branches of the preceding in Solipeds. j Homerat (BracutaL) Arrexy.—'This artery extends — from the external border of the pectoral musele to the bend of the elbow; here it divides into “two terminal — branches—the ulnar and radial, ca In its course it gives off several muscular branches, — 18, Posterior ulnar recurrent ; 19, Anterior interosseous ; - F 4 * J . THE BRACHIAL OR AXILLARY ARTERIES. 575 and an external and internal collateral of the elbow (collateralis ulnaris superior and inferior). In the lower third of the arm, the brachial artery is comprised between the brachialis anticus and inner border of the biceps; so that, during flexion, and- y active and forced flexion, of the fore-arm on the arm, in vigorous subjects, the ulation is arrested in the vessels of the hand. The radial artery of Man is repr:sented in the Horse by the posterior radial artery. Tt is directed downward and a little inward, supposing the hand to be in a state of r 1; it crosses the carpus in front of the trapezium and seaphoides, at the bottom of the anatomical snuff-box, and beneath the flexor tendons of the phalanges forms the - — palmar arch, finally anastomosing with a branch of the ulnar at the hypothenar _ eminence. Along its course it furnishes muscular branches: the carpea anterior ; radio- e palmar, which passes outwards, and unites with a branch of the ulnar to form the 8 r artery; the dorsalis pollicis; the carpea posterior, which coneurs in _ the formation of the dorsal arch of the carpus that gives origin to the dorsal interosseous ulnar artery, formed, in Solipeds, by the anterior radial, passes downward and The three arches that exist in the vicinity of the carpus, the constitution of which has been already given, are distributed in the following manner: The su palmar arch is situated at the surface of the flexor tendons; from its convexity it emits four or five metacarpal branches: the first reaches the external Arriote VII.—Parinirtve (orn Common) Carorm Arteries. (Figs. 282, 14; 286, 1.) Origin.— These two vessels (named from xdpa, the head) arise from the right axillary artery, at a short distance from its origin, by a common trunk, the cephalic, which is detached at a very acute angle, and is directed forward beneath the inferior face of the trachea, and above the anterior vena cava, to terminate near the entrance to the chest by a bifurcation that commences the two common carotids. Course—Each of these arteries afterwards ascends in the midst of an abundant, though dense, connective tissue, along the trachea, at first beneath that tube, then at its side, and finally a little behind its lateral plane. - Each carotid arrives in this way at the larynx and guttural pouch, where it divides into three branches. - Relations.—In its course, this vessel, independently of the connection between it and the trachea, affects the following relations :— - ‘Throughout its entire length, it is accompanied by the cord that results from the union of the pneumogastric nerve with the cervical portion of the sympathetic, and by the recurrent nerye; the latter is placed below or in front of the vessel, from which it is somewhat distant in the lower part of the neck; the first is situated dove or behind the artery, and lies close to it. It also corrosponds: behind, in its upper two thirds, to the longus colli a) 576 THE ARTERIES. and the rectus anticus major; outwardly, to the scalenus, towards the - inferior extremity of the neck, and to the subscapulo-hyoideus, bi separates the artery and jugular vein in the middle and superior part. But | | near the entrance to the chest, these two vessels are in direct relationship, _ the vein below and the artery ‘above. ses Tt is also to be noted, that the glands at the entrance of the chest are in contact with the carotids, and that the left artery corresponds, besides, to the esophagus. : CotntaTERAL Branoues.—The branches furnished by the common carotid — on its course are somewhat numerous, but they are of such inconsiderable diameter that their successive emission does not sensibly vary the calibre of the vessel from which they emanate; so that the carotids represent, from their origin to their termination, two somewhat regular cylindrical tubes. These collateral branches are destined either to the muscles of the cervical __ region, or to the cesophagus and trachea, Two of them, the thyro-laryngeal and accessory thyroid arteries, will occupy us in a special manner, 3 THYRO-LARYNGEAL ARTERY (Fig. 282, 14").—This vessel, which corre- ' sponds exactly to the superior thyroid artery of Man,‘ arises from the — common carotid at a short distance from its termination, a little behind the larynx or above the thyroid body; it passes on that organ, into which it enters by two principal branches that turn round its superior extremity and anterior border, after sending two branches to the larynx—a superior, des- tined also to the pharyngeal walls; and an inferior, much more considerable, which is exclusively distributed to‘the laryngeal apparatus. | It sometimes happens that the thyro-laryngeal artery is found divided from its origin into two quite distinct branches, each furnishing a laryngeal J and a thyroid division, as in figure 286, 3.? We have already remarked the disproportion that exists between the considerable calibre of the branches sent by this artery to the thyroid body, and the slender volume of that organ; so that it will at present suffice to remind the student of this peculiarity. “a Accessory Tayromw Arrsry (Figs. 282 14’; 286, 2).—The origin of this vessel precedes that of the first; it is much smaller, and enters the thyroid body by the posterior or inferior extremity of this glandiform lobe. This artery often sends only some excessively fine ramuscules to the thyroid gland, and expends itself almost entirely in the cervical muscles.* Tenminat Branonns.—The three branches which terminate the common carotid are the occipital, and internal and external carotid arteries; the latter is incomparably larger than the other two, which only appear to be collateral twigs from the principal vessel. It is these branches which distribute the — blood to the various parts of the head. We will devote three special paragraphs to their study; but their preparation will previously demand — some notice. 1 ! We would have given it the same name if we could have found the true repre- sentative of the inferior thyroid artery. - 2 It was doubtless a case of this kind that Rigot had before him when he described — : the above vessel, and made two arteries of it—the thyroid and laryngeal. But, we repeat, this example is only exceptionally met with, and does not authorize its being © supposed to be the rule, and cause the creation of a distinct thyroid and laryngeal bia since each branch of the vessel is distributed to the larynx and thyroid body at same time. * We regard it as the analogue of the middle thyroid of Man. THE COMMON CAROTID ARTERIES. 577 fa ration of the auietn of the head.—After carefully removing the skin, dissect the arteries of one side—thut is, the external maxillary, maxillo-muscular, the 1 trunk, and the posterior auricular arteries, excising the parotid to expose the zn of the three last-named vessels. On the opposite side, the deep arteries are prepared, after disposing of the branch of the maxilla, as in the preparation of the muscles of the tongue; the orbital and zygomatic processes being removed in three sections with the saw, as in figure 286, which will serve as a guide in the dissection of these arteries. ‘EB OCCIPITAL ARTERY. (Fig. 286, 6.) . ‘The occipital artery is a slightly flexuous vessel, lying beside the upper third of the internal carotid. It ascends beneath the transverse process of the atlas in passing behind the guttural pouch, between the maxillary _ gland and the straight anterior muscles of the head. It then insinuates itself between the small lateral straight muscle and the inferior arch of the above vertebra, to pass through its anterior foramen, and terminate by two branches, after coursing along the short fissure which unites this foramen with the superior. In its track, this artery is crossed, outwardly, by the pneumogastric and spinal nerves, and the occipital nerve of the great sym- pathetic, and is accompanied by the divisions of the inferior branch of the first pair of cervical nerves. e two terminal branches of the vessel are the occipito-muscular and inal arteries. ; The collateral branches are three in number, and in the order of their emission are named: 1, The prevertebral artery; 2, The mastoid artery; 3, The atloido-muscular artery. Cottaterat Branones.—1. PrevertepraL Artery (Fig. 286, 9).—The smallest of all the branches emanating from the occipital, this artery is detached at a very acute angle. and immediately divides into several filaments, some muscular, the others meningeal. The majority of the first between the occipito-atloid articulation and the small anterior rectus muscle of the head, and expend themselves either in that muscle, or the great rectus; the second, generally two in number, are always very slender, and reach the dura mater by entering, one through the posterior foramen lacerum, the other by the condyloid foramen. 2. Mastom Arrery (Fig. 286, -8).— This vessel arises at an acute angle above the preceding, and goes towards the mastoid foramen by ereeping on the external surface of the styloid process of the occipital bone, S beneath the small oblique muscle of the head. It enters the parieto- temporal canal by this foramen, to anastomose by inosculation with the inous artery. In its course it describes a curve downwards, and throws off a large number of collateral branches. Among these are some which originate before the artery enters its bony canal, and which are destined for tho muscles of the nape of the neck. Others arise in the interior of this canal, and escape from it by the orifices that cribble the temporal fossa, to expend themselves.in the temporal muscle. Some ramuscules reach the dura mater, We have seen the mastoid artery arise directly from the common carotid, and furnish a parotideal branch. 8. ArLompo-muscuLAR orn Rerrocrape Artery (Fig. 286, hays branch is not constant, and when it dees exist it presents a variable volume, It is detached from the occipital, unVerneath the transverse process of the atlas, by forming with the parent branch a right, or even an obtuse angle ; it is directed backwards, traverses the inferior foramen of the process of the 2P 5 ; Ps he 578 THE ARTERIES. atlas, places itself beneath the atlo-axoid muscle, and in a flexuous manner advances to meet the vertebral artery, which it directly joins, after giving off some branches to the great oblique and neighbouring muscles. anastomosis is the means of establishing a collateral communication between the vertebral artery, and the divisions furnished by the common carotid ; so that these two arteries can mutually assist or supplant each other. TerminaL Branones.—l. Occrrrro-musoutar Artery (Fig. 286, 10).— Covered at its origin by the great oblique muscle, the occipito-m artery is directed: transversely inwards to the surface of the posterior straight (recti) muscles, and soon separates into several branches—ascending and descending—mixed with the nervous divisions of the first superior cervical branch, all of which are destined to the muscles and integuments of the occipital region. The descending branches anastomose with the ter- minal divisions of the superior cervical artery. 2. CereBro-spinaL AnTery.—This vessel enters the spinal canal by the anterior foramen of the atlas, traverses the dura mater, and divides into two” branches on the inferior face of the spinal cord. Of these two branches, the anterior is united, by convergence, with the analogous branch of the opposite artery on its arrival at the middle of the length of the bulb (medulla oblongata), and so forms the basilar trunk ; the other passes backwards, and constitutes the origin of the median spinal artery, by anastomosing, after a short course, with the corresponding branch of the other cerebro-spinal artery. There results from this distribution a kind of vascular lozenge, situated at the lower face of the medulla oblongata, which receives in its middle the two cerebro-spinal arteries. This regular arrangement is not, however, always observed ; these arteries may unite at the posterior extremity of this lozenge, as is shown in figure 285. Basilar trunk.—This is a single vessel which creeps in a somewhat flexuous manner on the inferior face of the medulla oblongata, beneath the visceral arachnoid- membrane, and passing over the annular protuberance (pons Varolii), terminates at the anterior border of this portion of the encephalic isthmus, by anastomosing with the two posterior cerebral arteries (Fig. 285, 11, 11). On its course it gives off: 1. A multitude of plexuous ramuscules, which enter the substance of the medulla oblongata and the pons Varolii, or are distributed to the roots of the nerves emanating from the medulla oblongata. 2. The posterior cerebellar arteiies, vessels liable to numerous anomalies in their origin; they usually arise from the basilar trunk at a right angle, behind the posterior border of the pons Varolii, and bend outwards, one to the right, the other to the left, by gliding along the surface of the bulb (medulla oblongata), whose external border it thus reaches, and is then inflected backwards beneath the cerebellar plexus choroides, whence they spread their ramifications on the lateral and posterior parts of the cere- bellum. 3. The anterior cerebellar arteries, two or three on each side, only one of which is constant. These vessels are very variable in their disposition, and arise from the terminal extremity of the basilar trunk, in front of the pons Varolii, and sometimes even from the posterior cerebral arteries. Usually united in fasciculi, they are directed outwards and a little backwards in turning round the cerebral pedunculi, and plunge into the anterior part of the cerebellum. 4. Two branches anastomosing with the internal carotid artery; these THE COMMON CAROTID ARTERIES. 579 branches are not constant, and are most frequently met with in the Ass. They begin at the basilar trunk, in front of the posterior border of the annular protuberance, traverse the dura mater to enter the cavernous sinus, and join the carotid arteries at their second curvature. Posterior CeresraL Artertes.—These terminate the basilar trunk, and Sr into right and left of it, behind the pisiform tubercle (Fig. 285, 11). [hey first proceed forward, receiving posterior communications, then pass~ outward and upward, to turn round the cerebral peduncles and reach Bichat’s fissure. On their course, they furnish a multitude of hair-like twigs that enter the substance of the peduncles; but the principal branches they give off are flexuous, and directed either towards the great cerebral fissure, where they _terminate, to the posterior extremity of the hemisphere of the cerebrum, or its interior, to the plexus chorides more particularly, or even to the eerebellum. The disposition and number of these branches are very variable. Mepian Spivat Arrery.—A very long vessel, lodged in the inferior ' fissure of the spinal cord, and measuring the whole extent of that organ, which it follows from before to behind. It is from this artery that are given off the branches which cover with their arborisations the medullary tissue, or penetrate its substance. This emission, which ought soon to exhaust the artery, does not sensibly diminish its diameter, as it receives on both sides, during its course, numerous additional filaments. Two series of ramuscules, in fact, emanate either from the vertebral, intercostal, lumbar, or sacral arteries, and enter the spinal canal by the intervertebral foramina, and go to join this artery. Generally, however, they do not pass to thie spinal cord until they have anastomosed with each other outside the dura mater, so as to form on the floor of the vertebral canal two lateral conduits placed beside the venous sinus, and united by transverse anastomoses ; this disposition is most evident in the cervical region of the Ox (Fig. 288). INTERNAL CAROTID ARTERY. (Figs. 285, 8; 286, 5.) One of the terminal branches of the common carotid, the internal carotid ascends at first to beneath the base of the cranium, outside the anterior rectus muscles of the head, and bends forward to reach the lacerated foramen. In this primary portion of its course, it is suspended in a par- ticular fold of the guttural pouch, margined by the superior cervical ganglion, accompanied by the cavernous branch of the sympathetic nerve, and crossed in various directions by the nerves which form the guttural xus. On arriving at the middle of the occipito-spheno-temporal-biatus, it enters the cavernous sinus, and in the interior of that cavity, where it is bathed in venous blood, describes two successive and opposite curvatures ; the first looking forwards, occupies the carotid fossa of the sphenoid bone: the second, with its convexity posterior, at which the internal carotid receives an anastomosing branch from the basilar trunk: which branch is voluminous and nearly constant in the Ass; but is rare and, when present, very slender in the Horse. After the last inflexion, the two internal carotids communicate by a very large transverse branch, which is always flexuous, often reticulated, and leave the cavernous sinus in crossing the dura mater, to gain the cranial cavity. ‘Those arteries are then placed at the sides of the pituitary gland, within the superior maxillary nerve, proceed from behind forward, and terminate in two branches before reaching the optic nerve. One of these branches 2r2 580 THE ARTERIES. constitutes the posterior communicating artery the other soon bifurcates to form the middle and anterior cerebral arteries. Fig. 285. V.VEBMORCKEN ARTERIES OF THE BRAIN, B, Medulla oblongata; P, Pons Varolii; 1, Mastoid lobule; 0, Olfactory lobule ; c, Chiasma of the optic nerves ; M, Mamillary, or pisiform tubercle; u, Pituitary gland ; three-fourths have been excised.—1, 1, Cerebro-spinal arteries; 2, Median spinal artery ; 3, Lozenge-shaped anastomosis of the two cerebro-spinal arteries, from which result, in front:—4, The basilar trunk (usually the cerebro-spinal arteries arrive in the middle of the lozenge); 5, 5, Posterior cerebellar arteries ; 6, Anterior ditto; 7, Internal carotid artery, with the two curves it makes in the cavernous sinus ; 8, Internal carotid on the sides of the pituitary gland; 9, Transverse reticulated anastomosis thrown between the two internal carotids behind the pituitary gland; 10, Bifurcation of the internal carotid; 11, 11, Posterior cerebral arteries anastomosing behind the pisiform tubercle, receiving in the middle of this anastomosis the two terminal branches of the basilar trunk ; 12, Middle cerebral artery; 13, Anterior cerebral artery; 14, Posterior com- municating artery. THE COMMON CAROTID ARTERIES. 581 _ Posrertor Communicatine Artery.—This vessel is inflected backward on the side of the pituitary gland, and anastomoses behind it with the posterior cerebral artery. Mippte Crresrat Arrery.—This vessel separates itself from the an- terior cerebral artery, external to the chiasma of the optic nerves, is lodged in the fissure of Sylvius, passing through it in a flexuous manner, and at its extremity separates into several branches which ramify on the lateral and superior faces of the brain, and anastomose by their terminal divisions with the posterior and anterior cerebral arteries. Aytertior Ceresrat Agtery.—This enters immediately above the com- missure of the optic nerves, and proceeds inwards to unite, in the middle line, with the opposite artery, forming with it a single vessel. This median artery sa arteria corporis callosi) enters the longitudinal fissure of the brain ing round the anterior extremity of the corpus callosum, and, after a short course, divides into two branches which pass from before to behind, one to the right, the other to the left, on the internal face of the hemispheres, a short distance from the corpus callosum, and near the posterior extremity of that great commissure. The branches emitted by these arteries, either in their track or at their termination, anastomose with those of the posterior and middle cerebral arteries, as well as with the lobular branch of the ophthalmic. Before uniting in a common trunk, the two anterior cerebral arteries receive the meningeal branch of the ophthalmic, the calibre of which often even surpasses that of these vessels. EXTERNAL CAROTID ARTERY. (Fig. 286, 12.) _ This artery ought to be considered, because of its volume and direction, as the continuation of the common carotid. It is directed forward, arrives at the posterior border of the great branch of the os hyoides, passes between it and the great hyoid muscle, and is inflected so as to form an elbow which is turned forward, and afterwards ascends vertically to near the neck of the condyle of the inferior maxilla, at the posterior angle of the hyoid branch. There it bifurcates to give rise to the superficial temporal and internal arteries. ‘Serr In the first part of its course—that is, from its origin to the hyoid bone, the external carotid artery responds: inwardly, to the guttural pouch and the glosso-pharyngeal and superior laryngeal nerves ; outwardly, to the outer belly of the digastric muscle, and the hypoglossal nerve. | . In its second portion, it is comprised between the guttural pouch, the parotid gland, the great branch of the os hyoides,and the inner side of the posterior border of the inferior maxilla. _ The collateral branches this artery furnishes are three principal: the glosso-facial, maxillo-muscular, and posterior auricular, But it also gives off others of less importance, which are distributed to the guttural pouch, the guttural glands, and the parotid gland. 1. External Mawillary, Facial, or Glosso-facial Artery. (Fig. 286, 13.) It originates from the external carotid, at the point where that vessel passes beneath the great hyoid muscle, and is immediately inflected downwards on the side of the pharynx, between the posterior border of the large branch of the hyoid bone and the above muscle. It passes in proximity to tho anterior extremity of the maxillary gland, crossing Wharton’s duct outwardly, 582 THE ARTERIES. and leaves the deep situation it at first occupied, to become more en in the submaxillary space, where it rises on the surface of the internal pterygoid muscle, and is directed forwards to the maxillary fissure. Turning round this fissure, it climbs on the face, in front of the masseter muscle, to above the maxillary spine, where it terminates in two small branches. In its long and complicated course, the glosso-facial artery describes a semicircle upwards, and is very naturally divided, for the study of its relations, into three portions: a deep, an intermaxillary, and a facial. The first, or deep portion, accompanied in its superior moiety by the glosso- pharyngeal nerve, responds, outwardly, to the internal masseter (internal pterygoid) muscle; inwardly, to the guttural pouch, the hyo-pharyngeal muscle, hypoglossal nerve, middle tendon of the digastricus, the basio- glossus, canal of Wharton, and the subscapulo-hyoideus. The inter- maxillary, or middle portion, is bordered by the glosso-facial vein, lies against the pterygoideus internus, and is in contact with the submaxillary glands. The facial, or terminal part, is lodged, at its commencement, in the maxillary fissure, in front of the glosso-facial vein and the parotid duct; it ascends with these two vessels along the anterior border of the masseter. on the maxillo-labial and buccinator muscles, beneath the subcutaneous and zygomatico-labial muscles and the ramifications of the facial nerve, which perpendicularly crosses the direction of the artery. TerminaL Branones.—The external maxillary artery terminates in two small branches which separate from each other at an obtuse angle, one being directed upwards, the other downwards. The ascending branch passes to the surface of the elevator muscle of the upper lip, below the lachrymal muscle, and anastomoses with the divisions of a palpebral branch emanating from the supermaxillo-dental artery (Fig. 286, 19). The descending branch goes to the false nostril and the entrance to the nasal cavities, by creeping beneath the supernasalis-labialis muscle (Fig. 286, 20). CottatEeRAL Branones.—These are five principal branches: 1, The pharyngeal ; 2, lingual; 3, sublingual; all of which arise from the first portion of the glosso-facial artery; 4, The inferior and superior arteries, emanating from the facial portion. Besides these, there are a great number of innominate branches of secondary importance, which proceed to the neighbouring parts, and principally to the maxillary gland, sub- maxillary glands, the masseter muscle, and the muscles and integuments of the face. We will content ourselves with merely noting the existence of these latter branches. 1. Puarynezan Artery (Fig. 286, 14).—This arises from the glosso- facial, at a variable distance from its origin, and sometimes even in the angle formed by that vessel and the external carotid artery. Whatever may be its commencement, it is always directed forwards, passes between the hyo- pharyngeus muscle and the great branch of the hyoid bone, and describing some flexuosities, goes towards the pterygoid process, beneath the elastic layer which covers the pterygo-pharyngeus muscle (anterior constrictor of the pharynx). It terminates in the soft palate, after giving off on its course ascending and descending branches, which expend themselvesin the walls of the pharynx. 2. Linavat Artery (Fig. 286, 15).--As considerable in volume as the parent branch, this artery is detached at an acute angle from it, at the extremity of the hyoid cornu. With the glosso-pharyngeal nerve, it passes beneath the basio-glossal muscle, crossing the small branch of the os hyoides, and extends to the extremity of the tongue by gliding in the El —————— THE COMMON CAROTID ARTERIES. 583 Fig. 286, 7 GAMOCRBE ef 4. CHAUVEAU dub A GOWZLAND 2, LACERBAUVER ARTERIES OF THE HEAD. 2, Accessory thyroid artery; 3, 4, Thyro-laryngeal 1, Common carotid artery ; 2, artery, divided into two branches; 5, Internal carotid artery; 6, Occipital artery ; 7, Atloido-muscular artery at its exit from the inferior foramen of the atlas; 8, Mastoid artery; 9, Prevertebral artery ; 10, Occipito-muscular artery ; ¥3 %; ; I ) 584 wes THE ARTERIES, - ‘ interstice between the genio-glossus and basio-glossus muscles, where it meets the branches of the lingual and hypoglossal nerves, a. 9 Flexuous in its course, in order to adapt itself to the elongation of the = tongue, the lingual artery emits a very great number of collateral branches, = __ which escape perpendicularly from the entire periphery of the vessel; but chiefly above, below, and on the inner side, to ramify in the muscles — and integuments of the tongue. - ; ; THE ANTERIOR VENA CAVA, 615 roots, massed in a very dense network, converge towards the superior ions by diminishing in number and augmenting in volume, and terminate forming themselves, by the aid of successive anastomoses, into ten or twelve principal branches which again unite into two considerable vessels (Fig. 292, 6), situated at the superior limit of the plexus. These vessels, finally, by their last fusion at the inferior extremity of the first phalanx, constitute the digital vein, the satellite of the artery of the same neme (Fig. 292, 5). “Considered from below upwards, in a foot previously prepared by injection, the digital vein, divided into two branches, subdivides itself into secondary branches and ramuscules which diverge and spread over the convex surface of the cartilage and coronary cushion, resembling somewhat the disposition of trees trained on espaliers, whose spreading branches are fixed to the walls on which they ramify. . “The two peripheral branches of the superficial cartilaginous plexus establish communications with the opposite cartilaginous plexus, in con- tracting direct anastomoses with the branches of the plexus which are symmetrical to them. : “ The anterior anastomosing canals are double and superposed. “The most inferior and superficial is constituted by the large vein (Fig. 292, 3’) thrown slantingly across from one plexus to the other in the median plane, and on the external surface of the extensor tendon; this receives a considerable multitude of venous ramuscles, which emerge from the anterior part of the podophyllous plexus. “This first communicating vein joins the anterior branches of the carti- laginous plexus. _ ©The second communicating vein, situated three-quarters of an inch above the first, and beneath the tendon, is thrown transversely from one anterior branch of the plexus to the other. They open into each other on each side, at the same point where the first communicating vein enters. “Sinuous in the whole of its track, sometimes double, and sometimes formed of several confluent veins, as in Fig. 292, this anastomosing canal serves as an outlet for several deep veins. “The anastomosis between the posterior peripheral branches of the cartilaginous plexus is formed by an irregularly curved and long vein of large calibre, sinuous or broken in its course, but always considerably longer than the distance from the two cartilaginous plates between which it is extended. “This posterior communicating vein acts as a confluent to the canals emerging from the cartilaginous bulbs, and to the posterior part of the solar plexus, which throws into it five or six well-developed afferent veins. “Deep cartilaginous layer or plexus.—The deep layer of the carti- laginous plexus is formed : “1. By somewhat large ascending branches from the posterior part of the podophyllous and solar plexuses. “2. By the deep internal venous apparatus of the third phalanx. “3. By the deep veins arising from the coronary bone and the liga- ments and tendons surrounding it. “The ascending branches of the podophyllous tissue are introduced by the numerous foramina which traverse the base of the cartilaginous plate and the inferior fibrous covering of the plantar cushion; they follow the canals which continue those foramina in the substance of the cartilage, and reach its internal face, along with the branches proceeding from the intra-osseous 616 ; _ THE VEINS. venous system and those coming from the tendons and ligaments, forming @ fasciculus of five or six thick converging veins which unite in two large — ascending branches. ‘I'hese anastomose with each other before their de- finitive junction with the two peripheral branches resulting from the super- ficial cartilaginous plexus, with which we concur in constituting the digital vein.’ : 2a b. Internal,.or Intra-osseous Venous Apparatus. “ Girard, the younger, and Rigot have denied that the plantar artery had, in the interior of the phalanx, a satellite venous system. These two able— anatomists committed an error. —_. . “The disposition of the venous apparatus in the interior of the phalanx: a is absolutely identical with that of the arterial. wa “The satellite radicular venules of the terminal arteries converge, by = forming successive anastomoses, towards the semilunar sinus, into wl “| they enter by the anterior interosseous canals, ascending and descending, oe by which the emergent arteries from the semilunar anastomosis pass out- wards. There they join into a semicircular canal, the satellite of that’ | anastomosis, which is continued backwards. by two efferent veins that follow the posterior canals of the semilunar sinus, emerge by the plantar foramina, | pass into the fissure of the same name, ascend within the basilar process, __ lie at the internal face of the cartilaginous plate, in one of the infractuosities with which it is sculptured, and concur in the formation of the deep lye of the cartilaginous plexus. “ Beside these veins converging towards the cartilaginous plexus, there i is: -& a small number of divergent ones which follow the track of the arteries, and _ pass into the podophyllous plexus through the anterior porosities of the halanx. ae The dissection of specimens injected by the veins puts this arrangement of the venous apparatus in the interior of the os pedis beyond a doubt. _ “ But is this internal venous system limited to the group of vessels which are satellites of the arteries, or is it not rather extended over a vaster surface, and may not all the arcole of the spongy tissue of the bone be considered as a dependency of it ? “This way of viewing it would seem to be supported by the result Ce certain injections, in which the material introduced by the neighbourmg veins has-filled all the internal spongiole of the bony tissue; though this Ht was probably due to an accident in the operation, and it is presumable ethat = the direct passage of the venous injection into the areole of the spo tissue arose from a rupture in the vascular walls. If the tissue of the 3 phalanx formed a kind of diverticulum for the venous system, as the opinion a i just given would admit, operations performed on this part during life, when 3 the texture of the bone is deeply involved, ought to be followed by haw- morrhage from the open orifices of these ‘serola—a circumstance which does not take place. ‘Tt does not appear, therefore, that there is in the structure of the third — phalanx any departure from the general plan on which bones are constructed, and we think that its internal veinous system is limited to the vessels, rg numerous as they are, which accompany the arterial divisions.” = ‘es t é: THE POSTERIOR VENA CAVA. 617 - Anrione IIL.—Posrenton Vena Oava. (Figs. 258,-0; 259, f; 298.). _ This vein, whose volume is not equalled by that of any 6ther vessel in the body, commences at the entrance to the pelvis by two large roots, the pelvi-crural trunks. From this point 3 is directed forward, beneath the bodies of the lumbar vertebra, soon reaches the superior border of the liver, where it leaves the lumbar region to lodge itself in the fissure excavated on the anterior face of that gland; passing through this, it traverses the aponeurotic centre of the diaphragm, and opens into the postero-external part of the right auricle of the heart. In this course, the posterior vena cava is naturally divided into three portions—a sublumbar, hepatic, and thoracic. The sublumbar portion, placed to the right of the abdominal aorta and to the left of the right kidney and suprarenal capsule, is maintained against the common inferior vertebral ligament and the left small psoas muscle by the peritoneum and the pancreas. It responds, besides, to the right renal artery, which crosses its face perpendicularly, as well as the corresponding great splanchnic nerve and the nervous divisions of the right renal and " Tumbo-aortic plexuses. Tn its hepatic portion, the posterior vena cava is only related to the liver and dapliream. which form a complete canal around it. The thoracic portion is lodged between the right lung and its internal - aecessory lobule, and enveloped by a particular serous fold—a dependency from the right pleura, and which has been already described (page 465). Collateral afferents.—Those vessels which, as considerable as they are humerous, open into the posterior vena cava, are, enumerating them from before to behind : 1. The diaphragmatic veins. 2. The vena porte, a trunk into which are collected the majority of the visceral abdominal veins, and which, instead of opening directly into the vena cava, is divided in the liver. like an artery, reconstituting itself into a certain number of thick branches—the suprahepatic vessels, which enter the vena cava on its way through the anterior fissure of the liver. 3. i veins. 4, Spermatic veins. 5. Lumbar veins. All these vessels will be studied, in the order above indicated, before the roots or pelvi-crural trunks of the vena cava. DIAPHRAGMATIO VEINS, These are two, sometimes three, enormous vessels lodged in the texture of the aponeurotic centre, commencing by several branches in the fleshy portion of the muscle, and entering the vena cava at the moment when it traverses Mis disphregm. VENA PoRTRH. (Figs. 293; 294.) The manner in which this vessel comports itself gives it an altogether ‘peculiar physiognomy, and has caused it to be considered as a separate vascular system. After what has been already said concerning the structure of the liver, it cannot be ignored that the vena porte is distributed in that gland exactly like an artery. THE VEINS. 2 i) Fig. 293. Mae - 37733113 sanonon GENERAL VIEW OF THE VEINS IN THE HORSE. . THE POSTERIOR VENA CAVA, 619 It begins in the sublumbar region, at the great mesenteric artery, by the union of three large roots; it is then directed forwards and a little to the traversing the pancreatic ring, below the vena cava, and is afterwards in the great posterior fissure of the liver, where it ramifies by forming the subhepatic wats whose capillary divisions themselves give rise to the Suprahepatic and subhepatic veins (Fig. 219, VP, Vh).—These vessels having been already studied in the description of the liver, we need not again occupy ourselves with them, but refer only to a peculiarity incompletely noticed in that description, with reference to the suprahepatic veins. We know that these vessels are divided into two categories, according to the arrangement of their openings. The majority enter the vena cava in forming a single confluent placed at the anterior extremity of the fissure in the liver, at the diaphragmatic veins ; the others open separately over the whole extent of the hepatic portion of the venous trunk. In carefully examining the confluent towards which all the veins of the first group converge, we recognise the embouchures of three principal veins, one coming from each of the hepatic lobes, and furnished with three very thick, incom- plete valves. With regard to the vessels of the second group, M. Claude Bernard’ considers them to come, for the most part, directly from the sub- hepatic veins, and not from the capillary network formed by the arborisation of these veins in the lobules of the liver. It is true that injections readily penetrate from the vena porte into the vena cava, but they do this quite as much by passing along the large suprahepatic vessels as the canals of which we now speak; and, besides, if the material forced into the vena porte is mixed with some imperfectly-powdered colouring matter, the injection will arrive colourless, or but slightly tinged, in the suprahepatic vessels and the vena cava. These facts, we see, do not militate in favour of M. Bernard’s 1 * Lecons de Physiologie Experimentale. Paris, 1856. 1, Anterior vena cava; 2, 2, Posterior vena cava; 3, Right pelvi-crural trunk, divided at the ilio-sacra) articulation; 4, Left pelvi-crural trunk ; 5, Femoral vein; 6, Obturator vein; 7, Subsacral vein; 8, Left testicular vein; 9, Poste- rior abdominal vein; 10, Renal vein; 11, 11, Ascending branches of the asternal vein; 12, Vena azygos, with its intercostal branches, and in frout the subdorsal venous branch, 13; 14, (sophageal vein; 15, Dorsal, or dorso-muscular vein ; 16, Cervical, or cervico-muscular vein; 17, Vertebral vein; 18, Right axillary vein, cut at the anterior border of the first rib; 19, Substernal, or internal mammary vein ; 20, Left axillary artery ; 21, Termination of the left cephalic vein; 22, Left jugular; 23, Right jugular; 24, External maxillary, or glosso- facial vein; 25, Coronary vein; 26, Angular vein of the eye; 27, Subzygomatic vein; 28, Posterior auricular vein; 29, Maxillo-muscular vein; 30, Internal metacarpal vein ; 31, Median subcutaneous vein; 32, Radial subcutaneous vein; 33, Posterior radial vein; 34, Basilic vein; 35, Plat, or cephalic vein; 36, Coronary venous plexus; 37, Digital vein; 38, Internal metatarsal vein; 39, Anterior root of the internal saphena vein; 40, Posterior root of ditto; 41, Internal saphena; 42, Great coronary vein; 43, Small mesaraic vein; 44, Dif- ferent branches of the great mesaraic vein; 45, Trunk of the vena porta in its sublumbar portion, lodged in the pancreas; 46, The same in the po:terior fissure of the liver; below it is seen entering the substance of the gland.—m, Sub- scapular hyoideus muscle cut obliquely in the direction of the trachea; Pp, Cervical niculus turned down to expose the jugular channel; 0, Right auricle of the oe A, Posterior aorta; G, Section of the right lung; F, Left lobe of the liver behind the section of the diaphragm; R, Right kidney carried up and forward ; L, Esophagus; v, Bladder; 8, Rectum; 1, Thoracic duct; 1’, Termination of that duct in the confluent of the jugulars, 620 _ "THE VEINS. opinion ; and there is every reason to believe that the system of the vena p and that of the vena cava do not communicate, in the adult, otherviee 4 Fig. 294, THE VENA PORT AND ITS ROOTS; PARTLY THEORETICAL, 1, Trunk of the vena porte; 2, Its origin; 3, Veins of the small intestine; 4, llio- cecal vein; 5, External cecal vein; 6, In- ternal cecal vein ; 7, Great mesaraic vein ; 8, 9, Colic veins forming the roots of that vessel ; 10, Collateral vein sometimes con- tinuing the left colic, and joining the great mesaraic vein near its origin; 11, Com- mon confluent of the small mesaraic and splenic veins; 12, Small mesaraic vein and its collateral branches ; 13, Splenic vein; 14, Left gastro-epiploic vein; 15, Right ditto ; ; 16, Posterior gastric vein.—a, Stomach ; b, Duodenum ; c, Small intes- tine; d, Cecum ; e, Large colon; /, Float- ing colon ; 95 Rectum ; h, Portion of the great omentum ; 3%, Spleen ; 2d, meen ; k, Colic mesentery. dispense with any further description of them. -ecives on its course are principally — by the capillary network which intermediate to the subhepatic — suprahepatic vessels. If any of a means of communication exist, pe by must be extremely small, “a Constituent vessels of the vena porte. —The three roots of this vein are t! great and small mesenterics and the = splenic vein. oe ‘The collateral affluents it 1 two: the right gastro-epiploie veins : anterior gastric. - We will make a rapid survey " all these vessels. an) aes 1. Roots of the Vena Poa Bi * A. Great Mesenteric or AN reRIOR Muxsaratc Vein (Fig. 293, 44; 294, 2, 7).—This is an enormous 4 venous canal into which flows the blood that has passed through the walls of the small intestine, cecum, large colon, and the origin of the small — colon, and ‘whose divisions corres exactly to the different branches far- nished _by the great mesenteric — artery. = When. traced from its 0 to its origin, in an inverse 1 to the course of the blood, it is piesa to lie between the two colic f and proceed pepene the fold formed _ by the suprasternal and dia tie curvatures, beyond which Re dos q into two satellite branches for the colic arteries, which anastomose in — arcade towards the pelvic curvature, — like the arteries they accompany, = It is therefore by the union of two — colic veins (Fig. 294, 8, 9) that a great mesaraic vein is constituted, sh in-whose formation numerous collater al affluents concur; among these a bo noticed the two cecal veins (Fi 5, 6), the ilio-cacal vein (Fig. ate coming from the origin of the floating colon, and the veins of the small t tine: vessels arranged so exactly like the gorresponding arteries that we may 4 ca _, h _—e THE POSTERIOR VENA CAVA. 621 B. Smatt Mesenteric or Posterior Mesararc Vern (Figs. 293, 43; 294, 12).—This vessel commences above the rectum, near the anus, by large hemorrhoidal branches which communicate with the homonymous ramuscles of the internal pudic. It is directed forwards, between the two layers of the second mesentery, along the small mesenteric artery, which it and extends to the great mesenteric artery, on the left side of which . Paniios with the splenic vein, before opening into the anterior mesaraic to form the vena porte. In its course it receives all the satellite venous branches of the divisions of the artery of the same name, and whose a2 arrangement is similar to that of the arterial ramifications. ©. Sprextc Ver (Fig. 294, 13).—This is an enormous canal which follows the splenic artery, and comports itself exactly like it. It begins by the left gastro-epiploic vein (Fig. 294, 14) anastomosing in arcade with the right gastro-epiploic, receiving on its track gastric, splenic, and epiploic branches, and joining the small mesaraic after passing above the left ex- tremity of the pancreas, and obtaining the posterior gastric vein (Fig. 294, 16), 2. Collateral Afjluents of the Vena Porte. A. Ricur Gasrro-zrretorc Vern (Fig. 294, 15).—We already know that ___ the hepatic artery, before entering the liver, gives off pancreatic branches, a _ pyloric branch, and a gastro-epiploic division, which in turn detaches a small consi artery; the vessel described as the right gastro-epiploic vein cor- responds, in every respect, to all these collateral ramifications of the hepatic This vein, then, has its origin from around the great curvature of the _ stomach, but at an undetermined point, as it forms an anastomotic arch with the left gastro-epiploic vein. Posteriorly, it crosses the dilatation at the — of the duodenum, receives the pyloric, duodenal, and pancreatic veins, and opens into the vena porte after traversing tle pancreas. B. Anterior Gastric Vetn.— Satellite of the homonymous artery, this vein joins the vena porte separately, after the entrance of that vessel into the great posterior fissure of the liver, and when very near the terminal extremity of that fissure. RENAL VEINS. Two in number, like the arteries they accompany, these veins are dis- tinguished by their enormous volume and the tenuity of their walls. The left, having to cross the abdominal aorta before entering the vena cava, is longer than the right. They receive the majority of the veins from the suprarenal capsules (293, 10). SPERMATIO VEINS, These vessels correspond to the great spermatic arteries of the male, and the utero-ovarian arteries of the female. Testicular vein —The radicles which constitute this vein present, at their so from the superior border of the testicle, a flexiform and very complicated arrangement, enlacing, turning, and inflecting themselves in a thousand ways around the convolutions of the great spermatic artery, and ascending in this manner towards the neck of the vaginal sheath (abdominal ring), which they pass through usually after joining to form two trunks. These rise towards the sublumbar region, beneath the peritoneum, in a fold of which they are at first included; they communicate with one another in 622 THE VEINS. their course by anastomosing branches, and are generally confounded into a single spermatic vein, which opens into the vena cava near the renal vein (Fig. 293, 8). Utero-ovarian vein—This vein, which is very voluminous, enters the vena cava at the same point as the corresponding vessel in the male, and proceeds, as its name indicates, from the ovaries and uterus by flexuous and reticular branches, whose fusion into a single trunk only takes place near the vena cava, LUMBAR VEINS. Satellites of the arteries of the same name, these vessels enter the vena cava separately. The most anterior often open into the vena azygos. PELVI-CRURAL TRUNKS OR COMMON ILIAC VEINS, These appellations are given to two enormous vessels, into which are col- lected all the veins of the abdominal limb and the posterior part of the trunk—very short vessels, which, by their junction, form the posterior vena — cava (Fig. 293, 3, 4). The common iliac vein is lodged in the angle of separation comprised between the external and internal iliac arteries, and is a continuation of the two satellite veins of these arterial canals. The right, shorter than the other, passes above the external iliac artery to join the vena cava at its origin. The left, longer, insinuates itself between the body of the second last lumbar vertebra and the terminal extremity of the posterior aorta, to open into the other. If we trace, as was done with the veins of the anterior extremity, from the ungueal region to the pelvis, all the branches which concur in the formation of these two trunks, we will find, as the common point of de- parture for each, a rich subungueal plexus, from which spring two digital veins. To these succeed three metatarsal veins, the common origin of all the vessels of the leg. These latter are distinguished as superficial and deep, and are four in number—two saphena veins in the first group, and two tibial veins in the second—continued by the popliteal vein. ‘This vessel is itself continued by the femoral and external iliac veins, which finally form the pelvi-crural trunk by opening into the internal iliac vein. All these vessels will be studied in an inverse order to that in which they have been enumerated, and as follows: . Internal iliac vein. . External iliae vein. . Femoral vein. . Popliteal vein. . Deep veins of the leg. . Superficial veins of the leg. 7. Metatarsal veins. 8. Veins of the digital region. Oc cob 1. Internal Iliac Vein. This vessel is formed by the satellite veins of the branches furnished by the homonymous artery: these are the iliaco-femoral, obturator, iliaco- muscular, gluteal, lateral sacral, and internal pudic, whose distribution does not differ from that of the corresponding arterial divisions, y 4 ——— . | a a a THE POSTERIOR VENA CAVA, 623 The trunk resulting from the union of these different branches is usually very short; it may even be altogether absent, and we then see its con- stituent veins open into the common iliac vein by forming two or three separate groups situated very close to each other. 2. External Iliac Vein. This vein constitutes the principal root of the pelvi-crural trunk, which is but a continuation of it, the internal iliac being only, properly speaking, a collateral affluent of the single canal represented by the external and common iliac veins. ' Situated behind the crural arterial trunk, this external iliac vein com- mences at the anterior border of the pubis, where it is directly continued, without any line of demarcation, by the femoral vein. The only important vessel it receives on its course is the iliae circumflex vein, which, however, opens more frequently into the common than the external iliac. ; 3. Femoral Vein. Continuous by its superior extremity with the external iliac vein, and inferiorly with the popliteal, this femoral vein is remarkable for its large volume, and closely follows the artery of the same name throughout its extent (Fig. 293, 5). The collateral affluents it receives in its course are distinguished by their number and considerable volume. They are :— 1. The satellite veins of the muscular arteries. 2. The internal saphena vein, which will be again referred to in describin the superficial veins of the leg. 8. The prepubic vein, formed by the posterior abdominal and the branches of the internal pudic. The latter are very numerous and large, and anas- tomose with each other, forming between the thighs, in the texture of the scrotum and sheath, and above the penis, a very rich network which com- municates behind with the cavernous veins, This network only sends a small trunk into the inguinal ring, along the external pudic artery; in its middle part it opens into an enormous branch which traverses the ring in the sartorius muscle, and is lodged in the inferior groove of the pubis to join the femoral vein. One of these external pudic veins represents the subcutaneous abdominal vein, and communicates with the subcutaneous thoracic vessel. All these branches in the female show an analogous disposition. 4. Popliteal Vein. Satellite of the popliteal artery, this vein is formed by the union of the anterior and posterior tibial veins. Among the branches it receives on its course, the femoro-popliteal vein may be particularly noted; this accompanies the artery of the same name, and joins the external saphena before opening into the popliteal vein. 5. Deep Veins of the Leg. These are two in number: the anterior and posterior tibial, A. Anterior TrsiaL- Ven (Fig. 278, 5).—Placed beside the homo- nymous artery, often double, always very ample, this vein originates on the 624° THE VEINS. anterior face of fhe tarsal articulations by means of several anastomosing roots, the principal of which is formed by the deep metatarsal vein, that passes through the cuboido-cuneo-scaphoid canal from behind to before. After crossing the fibular arch with the artery, it joins the posterior tibial to constitute the popliteal vein. B. Posterior Trp Ver.—This commences near the hollow of the — hock, within the calcis, by radicular branches which principally come from the two saphena veins, It then ascends along its satellite artery, to open — into the anterior vein beneath the popliteal muscle. : 6. Superficial Veins of the Leg. These are the internal and external saphena. | A. Inrernat Sapnena Vern.—This vessel shows two roots—an anterior and posterior (Fig. 293, 39, 40). The first proceeds from the internal metatarsal vein, the second from the external. Both ascend, in converging towards each other, on the internal face of the tibia, uniting into a single branch before.reaching the thigh. This single branch, always very voluminous, glides upwards on the sartorius muscle, and terminates in a variable manner on reaching the groin ; sometimes it is insinuated into the interstice of the two addnctors of the leg, to join the femoral vein, and at other times it ascends to the ring of the short adductor, and opens into the external pudic veins. B. Exrernat Sarppena Vern.—It rises, by a short branch, outside the os calcis, communicates, even at its origin, with the posterior root of the internal saphena by means of a large reticular anastomosis thrown trans- ~ versely in front of the apex of the calcis ; and with the posterior tibial, by a large branch which passes between the tibia and the perforans muscle. It follows the external saphena nerve outside the gastrocnemii tendons, behind the external gastrocnemius muscle, and enters the popliteal vein, after joining the femoro-popliteal vessel. : 7. Metatarsal Veins. These veins are three in number, and are distinguished as external, and deep; they proceed from the sesamoid arch, which is formed by the anastomosis of the two digital veins. A. Internat Merararsat Vern (Fig. 278, 9).—This vessel, the most considerable of the three, appears more particularly to continue the digital vein of the same side. For the greater part of its extent it is placed with the internal plantar nerve, along, and a little in advance of, the flexor tendons. Arriving near the tarsus, it deviates slightly to reich the anterior face of the tarsal articulations, and there communicates, by a very large | transverse branch, with the origin of the anterior tibial vein; afterwards it rises on the internal face of the leg, where it constitutes the anterior root of the internal saphena vein. B. Exrernan Meratarsat Ver (Fig. 278, 8).—It occupies, outside the flexor tendons, a position analogous to the preceding. Towards the superior extremity of the metatarsus, it communicates, by a short thick branch, with the deep vein. It then continues its ascending course by entering the tarsal sheath along with the plantar arteries, and is prolonged — in the hollow of the hock, along the great femoro-popliteal nerve, in con- stituting the posterior root of the internal saphena. ©. Deep Merararsat Ver (Fig. 278, 10).—This “is placed benéath ee # THE POSTERIOR VENA CAVA, 625 the “suspensory ligament, at the inner side of the principal imteross¢ous ntar artery. Near the tarsus, it receives a very large branch from the tern l vein, and then traverses the euboido-cuneo-scaphoid canal, to form root of the anterior tibial vein. ; 8. Veins of the Digital Region. _ As these resemble, in every respect, those belonging to the anterior limb, the same description will suffice for both (see page 613). iS é 7 DIFFERENTIAL OHARACTERS IN THE VEINS OF OTHER THAN SOLIPED ANIMALS, It does not come within our plan to give a complete history of the venous system of these animals, because of the small utility of such a study. To remain faithful to the in view, we confine ourselves to the indication of the special characters of the on which bleeding is usually practised, and those which may be interesting in a ‘surgical point of view, as the digital veins of Ruminants. A. Ayee.ar VeIn or THe Eye—This vessel is femarkable for its large volume in the Sheep ; and as it is well defined beneath the skin, in consequence of the fineness of ' that membrane, it is more frequently selected for phleboiomy than in other animals. B. Jvueutar Vew.—Very large in all animals, and particularly in the Oz, this ve'n ‘deserves the preference given to it when it is proposed to abstract a certain quantity of ‘blood from the - Tn all non-soliped animals there is found an accessory jugular, which sometimes exists ‘in the Horse, but is much less in size, alongside the common carotid artery. It arises from the occipital vein, and, therefore, measures the whole length of the neck. Sometimes its diameter is small; but it is often so large as to receive a very notable quintity of blood from ed poem jugular, when compression is applied to the latter to favour the flow of blood after opening it: a circumstance which explains the difficulty sometimes ; in obtaining a voluminous jet of blood. C. AspominaL Scvovransovus Verx.—In the Bovine species, this vessel has an . enormous volume, especially in, the milch-cow, in contradistinction to the subcutaneous ‘thoracic vein, which is always very narrow. : _ This vein is prolonged forward on the wall of the abdomen, to nearly the xiphoid cartil where it passes through to join the internal thoracic vein.’ Behind, it is Sevan multiple branches, which avastomose with each other, or with those of the ‘opposite vein, and are in communication with the proper external purlic veins. _ _D. Inversat Saruena Vetn.—This is alway smaller than in Solipeds, and is rarely selected to bleed from. KE. Exrernat Saruena Vety.—This vessel is, on the contrary, more voluminous than in the Horse, and at the same time more superficial ; consequently, it is more favourably situated for phlebotomy, as well in Pigs and the Carnivora, as in Ruminants. It arises from the union, in the hollow of the hock, of the two principal roots furnished by the metatarsal veins. * F, Vets or trae Posrentor Foor in rue Ox.—As in the Horse, they commence in ‘the subungueal nelwork of the digital region, which is double, like the region itself. a. Three digital veins leave this reticulum: 1, A median or aaterior one, arising by two roots from the anterior part of each network, passing between the two digits, and the anteri®r superficial metatarsal vein above the fetlock ; 2, Two laterals, com- mubicating with one another, behind, by a transverse anastomosis which receives several venules from the ungueal plexus, and with the anterior vein by an interdigital branch, united by an arch in front of the flexor tendons, above the sesamoid groove. b. These digital veins are continued by five metatarsal veins: two deep and one por ge anterior, and two posterior. two deep anterior veins are small vessels which ry ye? the collateral artery of the eannon, which is placed between them. They arise in the interdigital space-from the anterior digital vein, communicating, by the inferior metatarsal foramen, with the seramoid arch, sending off on their way transverse anastomoses, and being continued above the tarsus by tlie two anterior tibial veins, whose roots they constitute. ‘The anterior superficial vein is very voluminous. It proceeds from the sesamoid arch, ! The openings through which these vessels pass in the abdominal parietes, are commonly named the milk fountains or doors. 9 8 eee SO eee le eee !l ee ” a ll = YY er “we Pe ee 626, THE VEINS. recdives near its origin the median digital vein, rises in front of, and a little to the outside of, the tarsus, communicating at this point with the anterior tibial veins; it divides above the tibio-tarsal articulation into two branches: a posterior, forming the — anterior root of the external saphena; the other anterior, joining the anterior tibial vein 3 of the oxternal side. The two posterior veins spring from the sesamoid arch, Situated at first between the P suspensory ligament of the fetlock and the posterior face of the metatarsus, and com- municating there by several anastomoses, these two veins are continued along the tarsus, the one within, the other without. The internal follows the corresponding plantar artery, and is prolonged in the tibial region by the posterior tibial and internal saphena veins. The external ascends within the calcis, aud is united toa branch of the anterior super- ficial metatarsal, to form the external saphena vein. Before leaving the deep situation it occupies below the suspensory ligament of the fetlock, these two vessels concur, especially the internal, to furm a perforating branch which traverses the cuboido-scaphoid canal to join the anterior tibial veins. G. Veins or THE AnTeRIOR Foor In THe Ox.—Four digital veins escape from the two subungueal plexuses: an anterior, posterior, and two . a. The anterior digital vein, which is very slender, is lodged superficially between the two digits, and comports itself at its origin like the analogous vein of the posterior limb, in rising by two roots. In being prolonged above the fetlock, it constitutes a “0 aoc ie + ( we ‘ ‘ . = subcutaneous metacarpal branch, which occupies the anterior aud internal plane of the — cannon, and is united above the knee to the principal cutaneous vein of the fore-arm, b. The posterior digital vein, often doubled by a small accessory branch, accompanies the common digital artery, and extends along the collateral artery of the cannon, to constitute one of the posterior radial veins. c. The internal digital vein, after passing the digital region, is lodged between the cannon bone and the internal border of the suspensory ligament, proceeds outside the carpal sheath with the radio-palmar artery, and divides above the knee into two branches; an anterior, the origin of the internal subcutaneous vein of the fore-arm; the other posterior, forming one of the posterior radial veins. d. The external digital vein occupies, on the outer side of the external digit and the cannon bone, a position avalogous to the internal vein. It gives rise to several deep metacarpal veins which anastomose, and are mixed with the interosseous palmar — arteries; the principal vein and its accessory branches are joined, below the carpus, to the internal vein. It is to be remarked that these four digital veins communicate, in the interdigital space, by anastomoses resembling those of the posterior limb; and that the last three, or principal veins, anastomose above the fetlock in forming a complicated and variably- arranged sesamoid arch, on leaving which these digital veins become metacarpal y 8. COMPARISON OF THE VEINS IN MAN WITH THOSE OF ANIMALS. In Man, as in animals, the veins are grouped into those of the lesser circulation, or pulmonary veins, and those of the greater circulation. The latter open into the heart by three trunks: the cardiac veins, and superior and inferior vena cava, ! The superior vena cava represents the anterior vena cava of animals, and receives the blood from the veins of the head, thoracic limbs, and a portion of the chest. It extends from the first costal cartilage to the heart, and commences after the junction of the two brachio-cephalic trunks (innominate veins). The superficial veins of the thoracic limb at first form, on the back of the hand, a plexus of elongated meshes from which the median, radial, and ulnar veins spring. Near the bend of the elbow, the median bifurcates and gives rise to the median cephalic and median basilie. Blood is abstracted from one or other of these branches. At the all the superficial veins constitute but two trunks: the cephalic and basilic veins. The deep vessels join these to form the azillary vein, which becomes the subclavian below the clavicle, then the brachio-cephalic trunk (vena innominata) when it receives the internal jugular. The venous sinuses of the cranial dura mater are pperanstely more developed than in Solipeds, though they have the same disposition. ‘There is constantly present a median or inferior longitudinal sinus, , ; The jugulars which carry the blood from the cranium and face to the heart, are four in number. The anterior jugular, the smallest, descends beneath the superficial cervical aponeurosis, in front of tle sterno-mastoideus muscle, and enters the subclavian vein. The external jugular commences by the union of the facial and temporal vein; in its disposition it resembles the jugular of the Horse, and would be a complete representative GENERAL CONSIDERATIONS. 627 if deprived of the branches from the cranial sinuses. The internal jugular arises at the 08 foramen lacerum, at a dilatation of the lateral sinus na the bulbus penx t and Sea to the subclavian vein. Lastly, the posterior jugular (or vertebral ) situated beneath tlhe great complexus, and in relation with the cervical vertebre, eurries the xt from the spinal sinuses in this region, and which, in Solipeds, is received and vertebral veins. The inferior vena cava corresponds to the posterior vena cava of animals, and receives the blood from all the subdiaphragmatic veins. It originates from the union of the two common iliac veins, at the third lumbar articulation, and terminates in the right Tn its course it receives the median sacral, lumbar, renal, suprurenal, inferior and right spermatic veins. ‘The latter forms on the surface of the testicle, and at of the cord, a rich network—the spermatic plerus ; on the abdominal portion of the it constitutes the pampiniform plexus. The vena cava also receives the vena porte, which has the same disposition as in animals, It begins by three branches : the great and small mesaraic and splenic veins. For affluents, it has the pancreatic and duodenal venules, and the right gastro-omental vein. It passes behind the pancreas, and not through that gland, as in the Horse. The veins of the abdominal limb are divided into deep and superficial. . The first terminate by forming the femoral vein, which, in joining ihe vessels of the pelvis, constitutes the common iliac vein. The superficial veins commence by a network on the dorsum of the foot, which gives origin to the two saphenas : external and internal. FOURTH SECTION. Tue LyMpHATICs. CHAPTER I. GENERAL CONSIDERATIONS. ‘Cuarcep with the absorption and transport of the chyle and lymph, the a or absorbent vessels are convergent canals with thin and transparent Ww which originate in the texture of organs by fine reticulated radicule ; and which, after traversing one or more ganglia (or glands)—glandiform bodies placed on their course—enter the venous system by two trunks: the thoracic duct and the great lymphatic vein. LYMPHATIC VESSELS, These canals resemble veins in so many points, as to merit the name of white-blood veins. Like these vessels, the lymphatics are directed from the periphery to the centre of the circulatory apparatus; like them, they are nodulated cylindrical tubes; internally, and at those points where they outwardly appear to be constricted, they show numerous valves which look towards the heart; like the veins, again, they separate into two orders of canals: the ones deep-seated, lod in the vasculo-nervous intermuscular sheaths; the others superficial, situated on the surface of containing apon- euroses ; like the veins, also, the lymphatics terminate in two principal trunks resembling the vene cave; and, finally, as the veins haye three tunics, so have the lymphatics, these not differing in any respect, except in being very much thinner. In carrying this parallel still farther, we will find other analogies whose existence was but little suspected until recently: the glands—those organs which are apparently glandular, and seem to be proper to the lymphatic system—are they not represented in the venous system ea! Se liver— 8s 2 628 THE LYMPHATICS. that enormous gland placed on the track of the abdominal veins—as the glands are on parts of the lymphatics ? It may be added that, if we pass into the domain of physiology, it is also. easy to observe characters which are common to the two anatomical systems under comparison They, in fact, almost equally divide the absorbent function between them: a function which is accomplished in the radicular network of each; and the dynamical process which gives impulsion to the /fluids they carry, if it is not quite identical in both, is at any rate very simschan in many points. We may, nevertheless, observe numerous differences between the veins ma the lymphatics, and chiefly i in their form, number, capacity, and structure. The form of the lymphatic canals is, as we have said, nodulated and cylindrical ; but their external nodosities are much less marked, and are closer together than in the veins, owing to the larger number and greater develop- | ment of the valves. Besides, as these canals travel for considerable distances, and preserve their regularly-cylindrical form with undiminished capaci if we mentally bring all the divisions of the lymphatic system to a ing canal, we no longer obtain a hollow.cone whose apex corresponds with heart, although the capacity of the\lymphatic vessels augments from the trunk towards the branches; this conduit only represents a series of cylinders joined end to end, and successively decreasing from its origin to its termination. The number of lymphatic vessels in a certain region is always much | greater than that of the veins. But as the lymphatics are much smaller than the veins, there is not, as might at first be supposed, a proportional increase in their total capacity. Observation, indeed, demonstrates that the relation between the capacity of the lymphatics, and the corresponding veins of a region does not exceed one to two. The structure of the lymphatics differs from that of veins in that there exists, in those of average dimensions, smooth muscular fibres in the adven- titious tunic. The presence of muscular fibres in the external tunic of these vessels is rendered necessary by the absence of an impelling organ at the origin of the lymphatic system: this organ being, in reality, disseminated throughout the extent of the canals, and aids the vis a tergo that causes the lymph to circulate in their interior. We terminate this short parallel, to dwell in detail on several points connected with the general history of the lymphatics, and which merit particular attention; we allude to the origin, course, and termination of these vessels. Ortatx.—F or a long period after the discovery of the lymphatic vessels, a state of profound ignorance existed as to their origin. Nevertheless, the importance of the solution of the problem was well appreciated, as it was really the, key to the theory of absorption; numerous hypotheses, therefore, sprang into existence. The anatomists who occupied themselves with the question were hindered in their investigation by the imperfect means of rescarch at their disposal. Beyond the larger branches, the lymphatics escaped attention, owing to their transparency and tenuity. Thanks, how- _ ever, to the patient and minute researches of Hunter, Cruikshank, Mascagni, \ Fohrann, Panizza, Cruveilhier, and Sappey, the lymphatics were injected by colouring matters or by mercury, and thus rendered visible to their finest ramifications. It is now known that the lymphatics arise from capillaries, which form — networks or terminal cnls-de-sac. Ny alle bigiaine Pa ee a GENERAL CONSIDERATIONS. 629 These terminal culs-de-sac exist in the intestinal villi ; and itis no longer maintained that the ends of these small appendices have an opening by which the lymphatic receives the chyle that bathes the mucous membrane of the intestine. The are composed of more or less irregular meshes, and their form and volume often vary with the disposition of the tissues or organs in which they are studied. They may be superficial or deep, and exist together or separately. In many membranes the two networks are found, but then the superficial is thinner than the deep. They are mixed with, or placed _ above, the blood-vessel plexuses, but never communicate with them. - Do these lymphatic plexuses exist in all the tissues, properly speaking ? Here is another question of incontestible importance, and whose solution is even now occupying the attention of anatomists. Judging by analogies, one is tempted to reply in the affirmative: why, in fact, should the lymphatics not be spread everywhere throughout the organism, when the sanguine capil- laries are constituent parts in the framework of each tissue? It is true we may ask if lymphatic absorption is a necessary act in the vital movement ; and although science is far from being satisfied on this point, we know some facts which at least authorize the doubt. On the other hand, direct ob- servation has not revealed lymphatic plexuses in all organs; there are even tissues in which their existence has been denied: though prematurely, it is well to say, because we may always attribute the non-success of a lymphatic injection either to the imperfection of the instruments employed, the insufficiency of the measures adopted, or certain peculiar conditions as yet unknown attaching to the species of animals selected for the demonstration of the lymphatic networks in a certain region. As bearing out this last assertion, we may observe that M. Sappey has not yet been able to inject the pituitary plexuses in Man or the Calf, and that he looks upon their existence as being at least doubtful; while in the Horse, this lymphat‘e apparatus is as remarkable for its richness, as for the facility with which it may be filled with mercury. The following are the most trustworthy notions available on this subject. The lymphatic vessels of the skin are very numerous, and form two net- works: one, with extremely fine meshes, occupies the most superficial layer of the dermis ; the other, placed beneath the deep face of the integu- ment, includes vessels more voluminous than the first, and communicates with it by multiplied ramuscules. These lymphatic plexuses are far from being equally developed in every region: though it is unanimously agreed that no part is entirely destitute of them. In the internal tegument, or mucous membranes, an analogous disposition of these vessels is met with. It is more than probable that they exist throughout the whole extent of these membranes, though their positive demonstration has yet to be made in some regions. In other regions, the injection of these networks is, on the contrary, very easy, and gives the most magnificent results; we particularly mention the lingual, intestinal, and pituitary mucous membranes. The lymphatics belonging to the latter membrane assume so beautiful an aspect in the Horse, that we would advise anatomists who desire to inject lymphatics always to choose that animal. The operation is simple and constantly performed, and we are astonished that in the hands of some individuals it should fail. Not only can the two networks of the membrane be filled, but also the trunks arising from them, and which are directed towards the entrance of the nasal cavities, collect in several thick branches around the nostril, and bend up towards the face 630 THE LYMPHATICS. to reach the submaxillary cavity, where they enter the ganglia situated to the right and left of that space. The majority of anatomists admit the presence of lymphatic plexuses in the splanchnic or synovial serous membranes. M. Sappey, however, denies this; he considers the vessels that can be so easily injected by pricking the external surface of a viscus, as belonging to its proper tissue, and not to the serous membrane covering it. Those on the inner face of the walls of the splanchine or synovial cavities, and which are sometimes filled with mereur merouy do not, according to him, come from the serous tunic, but from the su jacent tissues. The lymphatics do not exist in vessels, although some modern anatothiate have admitted them to be present in the inner layer of the circulatory apparatus, The lymphatic sheaths discovered by His, Robin, and Tomaso, around the blood-capillaries of the frog, and those of the brain and spleen of Man, ought not to be considered as the lymphatics of vessels, as they merely surround the ultimate vascular ramifications, and do not arise in the substance of their walls. In the nervous tissue lymphatics have not been discovered, thongs they are present in the meninges. Their existence is doubtful in bone tissue and in the muscles ; but they are abundant in the glands and glandiform organs of the animal economy, forming the finest, richest, and most easily demonstrated plexuses. It has been stated above that the lymphatics commence by capillaries arranged in networks. Are these networks the real, or only the apparent, origin of the lymphatics? This is a question that has been, and is still, warmly discussed, It is, however, believed that the plexuses are fed by very minute radicles lodged in the substance of the tissues. But how do these radicles originate? In the epithelium, says Kiiss; in the plasmatic cells of the connective tissue, asserts Virchow; in the serous membranes, states Recklinghausen, since he observed fatty matters pene- trate the lymphatics by the abdominal face of the diaphragm. ‘The opinion of Virchow is overthrown at present by the researches of Ranvier, which have modified the descriptions given of the connective tissue. According to this authority, plasmatic cells do not exist in that tissue; what have been described as such by Virchow have been only radiating spaces limited by the fasciculi of connective fibres, in which elements analogous to lymph globules circulate. It may be added that these fasciculi are covered by large flat cells, which give these spaces the appearance of a serous cavity with septa at close intervals. These conclusions of Ranvier, then, should affirm the hypothesis of the Wiirzbourg professor, and tend to prove that in the connec- tive tissue of the economy there is an infinite number of minute serous cavities into which the lymphatic vessels open, in which the lymph circulates, and which are in communication, on the other hand, with the great a cavities. It must be mentioned, however, that these deductions are onl hypothetical, particularly at the period of scientific evolution throug which we are now passing. Course or tHe Lympnatic Vessets.—The lymphatics follow the track of the veins, and are divided, exactly like them, into superficial and deep vessels. The latter, running parallel to each other, are grouped immediatel around the corresponding veins, on which they are generally su The first, although situated in proximity to the superficial veins, are widely spread on each side and on the surface of the superficial aponeuroses, i forming parallel fasciculi, like the deep lymphatics, GENERAL CONSIDERATIONS. 631 The direction followed by the lymphatics in their course is nearly always somewhat rectilinear ; they never show the flexuosities which are so developed on the track of certain arteries, and even some veins. Neither do they communicate with one another by transverse or arching anastomoses, like those so commonly met with in the other two orders of canals, belonging to the circulatory apparatus. They frequently, however, in their parallel course, bifurcate and join the neighbouring vessels. (At certain situations, as at some of the articulations, and in other parts, the larger stems suddenly break-up into a close interlacing plexus of small vessels or capillaries (Pig. 295), which in their disposition, greatly resemble the rete mirabile of the blood-vessels. This plexus is surrounded by condensed connective tissue, and is penetrated by blood-vessels, though no communication takes place between them and these, the only points at which communication occurs being where the great lymphatic trunks empty themselves into the vena cava. This rete would appear to be the first step towards the formation of a lymphatic gland.) A SECTION OF A SIMPLE RETE MIRABILE, VIEWED FROM THE SURFACE. a, a, Afferent vessels; 6, 6, Efferent vessels only partially visible; from the popliteal space. But of all the considerations relative to the course of these canals, the most interesting are those which belong to the glandiform bodies placed along their track, and whose abridged history we shall give immediately. Termination.— We have already mentioned the thoracic duct and the right great lymphatic vein as being the receptacles of all the absorbent vessels of the body, and we have also stated that these two trunks enter the general venous system ; this union of the sanguine with the lymphatic system takes place at the origin of the anterior vena cava, and this vessel may be con- sidered as the general confluent for all the absorbents. The researches of Haller, Cruikshank, and Mascagni first threw light on this important fact ; and it is to those of Fohmann, Panizza, Rossi, &c., that we owe the dedi- cation of this discovery. 682 THE LYMPHATICS. LYMPHATIC GLANDS, The lymphatic glands are ovoid, spherical, or discoid bodies of mehiaee consistency, grey, rosy, or red-coloured, and sometimes quite black, and which at several points intercept the course of the lymphatic vessels. Their ‘number is considerable, and they are rarely isolated ; mest | frequently they are collected in groups along the blood-vessels. They are always larger in youth than in old All the canals of the vine: system are provided with at least one gland on their course, and some even traverse two or three before opening into the thoracic duct or great lymphatic vein. On reaching these glands, they plunge into their structure in ramifications, appearing on the opposite point after being reconstituted into several principal canals, which are generall larger and less numerous than the primitive vessels. The latter take the name of afferents (vasa inferentia or afferentia); the others are named efferents (vasa efferentia), because they leave the gland to reach the central canal. Srrvoture.—The structure of the glands is extremely complicated, and difficult to make out, in consequence of the delicateness of their tissue. The_ following is what is positively known in reference to this subject. The glands have an envelope of connective tissue (continuous with the tunics of the afferent and efferent vessels), which surrounds a substance that is readily perceived to be composed of two layers of a different aspect: one cortical, the other medullary. The first appears to be granular, the second somewhat fibrous. This proper tissue is sustained by connective lamine (or septa—continuations of . the capsule) which contain smooth muscular fibres. The laminew form alveoli in the cortical layer, and a sort of minute tubes in the central layer. These alveoli are in their turn divided by reticular tissue into secondary spaces, which become smaller as they lie near the centre; at the periphery, where Fig. 296. pe 297, SIMPLE LYMPHATIC GLAND. a, The capsule with sections of lym- phatics, d, d, passing through it; b, Lacunar and epee SECTION OF A LYMPHATIC GLAND. a, a, The fibrous tissue that forms its exterior; 5, }, passages, permeated by the | Superficial vasa inferentia; ¢, c, Larger alveoli, and forming the superficial lym near the surface; d, d, Smaller alveoli of the path of Frey; c, Nucleus, pa nee interior ; ¢, ¢, Fibrous walls of the alveoli. dullary portion, with section of blood-vessel in the centre. they are most voluminous, they are named lymphatic sinuses, Every where these sinuse3 are filled with lymph globules. The arrangement is identical a GENERAL CONSIDERATIONS. 633 in the medullary substance ; in the interior are seen a great number of arterial capillaries, The nerves are derived from the sympathetic system. _ _ The atferent lymphatics, where they enter the gland, communicate with the alveoli which correspond to ¥ the cortical substance ; these al- Fig. 298. yeoli are connected by the cords of the central layer, and the latter are united, in their turn, to the alveoli of the opposite side of the cortical substance, from which the mt ramuscules spring. The lymph, therefore, traverses every part of the gland, and during this very tortuous course becomes charged with solid particles. Certain glands have a much more simple structure, being en- tirely composed of lymphatic capil- laries rolled up on themselves in clusters, and anastomosing in net- works. These capillaries arise from the divergent arborisation of the afferent vessels, and are contin- uous with the convergent branches which, by their union, form the efferent lymphatics. The organs have received the name of false glands, though they are really PORTION OF THE MEDULLARY SUBSTANCE OF THE lymphatic glands. In support of p ae aban GLAND OF AN OX, THE ARTERY this assertion, it may be said that ; yan; ahead 200. “psa aasctae aa “in descending the animal series, a, Medullary substance with capatilry: network - we see the glands becoming more fine reticulum of connective tissue, and a few and more simplified, and trans- lymph eorpuscles; 6, 6, Superficial lymph- formed at a t number of points path, traversed by a reticulum of nucleated 2 2 ‘ eells (¢ c), with numerous anastomosing pro- ~ into an interlacing of vessels. In longations. The lymph corpuscles have. for birds, they only occupy the base the most part been removed; d, d, Trabecule of the neck and the entrance to the —_ composed almost exclusively of unstriped mus- chest, forming in all the other cular tissue; y, A small medullary cord, of regions simple plexuses ; in rep- bridge, containing a blood-vessel and numerous tiles and fishes, the lymphatic glands _ ys disappear altogether, and the plexuses that replace them are themselves not at all complicated.”— Sappey. , Preparation or THE Lymruatic Vessers.—The epee networks can only be studied after having been filled with mereury by means of injection; but as this opera- tion is not usually practised by the pupils fur whom this book is written, the ticde of performing it will only be traced in a few words. The apparatus in use consists of a glass tube continued by a flexible one, which carries at its inferior extremity an iron tap and a fine canula, also of iron, or (better) glass. To apply tiis apparatus, the tube ought to be suspendid and then filled with mercury ; the canula is then seized by the right hand, keeping it parallel to the membrane we wish to inject, and burying it in the most superficial layer of that membrane. The extremity of the canula is thus introduced into the midst of the meshes of the lymphatic network, »nd necessarily wounds some of the capillaries which compose it. In opening the tap, the mercury is ullowed to flow into the capillaries by the solutions of continuity they present, and fills them in the most perfect manner. The lymphatic plexuses being 684 THE LYMPHATICS. : only, in taking the precaution to penetrate the membrane as superficially as the point of the canula enters too deeply, the mereury will pews into the v operation will be unsuccessful, and must be commenced again. To study the branches and lymphatic trunks, it will suffice to inflate them from their origin towards their termination. This proesee properly conducted—and it was almost exclusively the only one adopted by the older anatomists—gives the most sutis- factory results, and is even sufficient to demonstrate the texture of the glands. Pil Je The latter do not require any particular precautions in their preparation. Je always superposed on the eapillury blood-vessels, one is always certain of injecti g them and the CHAPTER II. THE LYMPHATICS IN PARTICULAR. f= 4 We will commence with the examination of the thoracic duct and all its affluents, and terminate by studying the great lymphatic vein. In this description the glands and principal lymphatic vessels will be only referred to, the disposition of the networks being already noticed — in speaking of the different organs, and they will be further mentioned when speaking of the nervous system, the organs of sense, and those of generation, Articte I.—Tur Txoracic Door. (Fig. 293, 7 r.) Preparation.—Tie the jugulars and axillary yeins near their termination, as well as the anterior vena cava about the middle of its length; expose the thoracie duet by removing the ribs on the right side; open that canal neur the pillars of the diaphragm, and throw into its interior two injections of tallow, one forward, the other backward from the incision. The first injection will fill the canal and the venous reservoir which is intersected between the ligatures applied to the above-named vessels; the second, although directed in opposition to the valves, overcumes the resistance offered by them, and passes into Pecquet’s cistern and the principal branches which open into thut confluent. Or we may select one of these branches in the abdominal cavity—for example, one of those which lie beside the colic arteries near their origin—and inject the entire thoracic duct from its origin to its termination. But this proceeding requires more practical ability than the first, in order to find - the vessel which is to receive the canula; and if the animal is very fat, it is im- possible, The thoracic duct is the general confluent for all the lymphatics of the body, with the exception of those which come from the right anterior limb and the right moiety of the head, neck, and thorax. . Extent.—It extends beneath the vertebral column, from the first lumbar yertebra to beyond the entrance to the thorax. Origin.—Its origin is marked by a very irregular dilatation described as the sublumbar reservoir, or cistern of Pecquet (receptaculum or cyster nachyli), into which open the principal affluents of the canal. oe This reservoir is divided, internally, by lamelle into several incomplete __ compartments, and may be more or less voluminous and circumscribed, and _ present very variable forms. a It is placed above the abdominal aorta and the posterior vena cava, at — the great mesenteric artery, or more frequently a little behind it. In the Dog it is of an enormous size, oval in shape, and prolonged between the — pillars of the diaphragm into the thoracic cavity, 4 Course.—To this reservoir succeeds a tube whose calibre is very irregular, — and appears singularly slender when compared with the diameter of the * _ a ee — THE THORACIC DUCT, €35 initial dilatation, or that of the affluent vessels composing it. This is the thoracic duct. We see it enter between the two pillars of the diaphragm, ng with the aorta, deviating more or less to the right side of that vessel, and follow it thus to about the sixth dorsal vertebra, in passing to the outside of the right intercostal arteries, which it crosses, and beneath the great vena “azygos, beside which it lies. Sometimes, however, we find it carried in this first part of its course directly above the thoracic aorta, between the double series of intercostal arteries, and to the left of the vena azygos, which is then found immediately in contact with the right side of the aorta; or it may even creep to the right of that vein, concealing the greater part of it from sight. Leaving the above-mentioned dorsal vertebra, the thoracic duct abandons the aorta and crosses the flexure of the vena azygos to the left, to extend itself forward on the left side of the trachea, but often also on the right side. It afterwards places itself between the two axillary arteries, crosses the interval comprised between the prepectoral glands, emerges from the chest, and terminates in a manner to be indicated - hereafter. Termination.—The terminal extremity of the thoracic duct is always provided with a dilatation analogous to that which exists at its origin, though much smaller, better circumscribed, and less irregular—a dilatation which © opens into the anterior vena cava sometimes by a single orifice furnished with valves, at other times by two very short branches, whose length we cannot estimate at more than the fifth part of an inch, and which are also valyular at their entrance. The point where this entrance takes place is nearly always at the summit of the vena cava, and precisely at the point of junc- tion of the two jugulars. The thoracic duct rarely opens elsewhere ; though the fact that it does so at times is exemplified in a specimen in the museum of the Lyons School, in which the embouchure of the duct is placed between the termination of the left jugular and that of the corresponding axillary vein. Varieties in Solipeds.—* The thoracic duct is far from always showing © itself in Solipeds as I have described it, but in its course and insertion presents a great number of variations which we will now pass in review. _. * The single canal is separated sometimes, at a part of its length, into two branches, which, after proceeding parallel to each other, soon unite to form a single vessel. This division usually takes place at the base of the heart, at the place where the lymphatics of the bronchial and cesophageal glands enter ; it forms a ring whose diameter is often not more than four-tenths of an inch, or an ellipse whose larger axis is from four to eight-tenths of an inch, We see this produced once, twice, and even thrice on the anterior half of the canal, which becomes simple at its termination as it was at its origin. The spaces circumscribed by the bifurcations constitute what have been termed the insule. “The canal, instead of remaining single, very often becomes double from its commencement (Fig. 300). Then the two canals are sensibly equal, or one is larger than the other. If they are unequal, it is usually the right which has the advantage, though the contrary sometimes oceurs. In any case, the two canals are isolated, one being to the right, the other to the left of the aorta. In advancing towards the entrance to the thorax, they remain completely separated, or communicate with each other by one or two, more* or less voluminous, transverse anastomosing branches. Reaching to ten, eight, and sometimes even to two inches from their opening into the jugular gulf, the two canals approach each other, and become confounded into a single 636 THE LYMPHATICS. Fig. 299, Fig. 300. Fig. 301. DIFFERENT VARIETIES OF THE THORACIC DUCT IN THE HORSE, A, Receptaculum chyli; B, Sublumbar branches; c, Anterior mesenteric branch ; p, Posterior mesenteric branch. In ficure 299 the duct is single, the usual condition, and enters the “affluents. AFFLUENTS OF THE THORACIC DUCT. 637 vessel. Their fusion generally takes place at the base of the heart, and Thave never seen them remain distinct throughout their whole extent, to enter the vena cava separately. ' “Sometimes (Fig. 301) there emanates from the gland, at the entrance ‘to the thorax, a long canal which proceeds parallel to the first, and joins ‘it, after a retrograde course, near the pillars of the diaphragm. __ The thoracic duct, double for the greater part of its extent, from the ‘time it leaves the sublumbar reservoir, occasionally ends by becoming In this case, the largest of the two canals is divided into two branches ; then the three canals, after pursuing a certain course, all join at the same point, or two are first.united into a single conduit, into which the ‘third opens at a variable distance from the confluent of the first.” i The affluents of the thoracic duct.—The lymphatic branches which enter the thoracic duct are as remarkable for their number as their volume, ‘Some empty themselves into the sublumbar reservoir; a few vessels open into the great lymphatic vein of the thorax, and the others terminate in that conduit, near its insertion into the venous system. The first, variable in their number, particularly the largest, are more especially regarded as the roots of the thoracic duct. _ Ordinarily three are found, with a certain number of small accessory trunks. One of the largest branches enters the posterior part of the cistern ; ery often double, and even multiple, it arises from an enormous group of ganglia placed in the sublumbar region, around the posterior extremity of the abdominal aorta and vena cava, and into which are collected all the ‘vessels of the posterior limbs, the pelvis, abdominal walls, and the pelvi- inal viscera. The other two trunks reach the left side of the cistern, and result from the union of the lymphatics which have their source in the abdominal digestive organs; among these lymphatics, however, there are some belonging to the parietes of the stomach and the parenchyma of the liver and spleen, and which approach the right side of the sublumbar recep- tacle, to open singly into that cavity. The affluents the thoracic duct receives on its course, proceed from the viscera contained in the thoracic cavity, and from the walls of that cavity. Those which terminate at the anterior extremity of the duct are formed by the lymphatics of the left anterior limb, and the left half of the thorax, diaphragm, neck, and head. We will now examine rapidly all the radicular branches of these Arrticte I].—Tue Lympnatics wHich rorM THE AFFLUENTS OF THE 74 Tuoracic Dvucr. These lymphatic vessels are divided into five groups: 1, Those of the abdominal limb, the pelvis, abdominal parietes, and the pelvi-inguinal organs; 2, Those of the abdominal digestive viscera; 3, Those of the ‘organs contained in the chest; 4, Those of the thorax; 5, Those of the head, neck, and anterior limb. 1 G. Colin. * Traite de Physiologie Comparée des Animaux Domestiques,’ vol. ii summit of the anterior vena cava by two short branches. It is double in Figure 300; and in Figure 301 it has a long branch that arises at the entrance to the thorax and joins the duct, by a retrograde course, near the pillars of the diaphragm. 6388 THE LYMPHATICS. LYMPHATICS OF THE ABDOMINAL LIMB, PELVIS, ABDOMINAL PARIETES, AND | THE PELVI-INGUINAL ORGANS, All these vessels converge towards an immense group of ganglia, seal the sublumbar glands, Besides these, there are other groups on different parts of their track, constituting the deep inguinal, superficial inguinal, popliteal, iliac, and precrural glands. The successive description of these ganglia, and their afferent and efferent vessels, will conveniently make known the lymphatic apparatus, whose study we have in view in this paragraph. 1. Sublumbar Glands, This group, which occupies, as its name indicates, the sublumbar region, comprises; 1, A small single mass situated in the sinus of the angle formed between the two internal iliac ar teries, and is often formed by a single large ganglion; 2, Another mass lodged between the two iliac arteries, and a third placed without, and to the front of, the crural trunk: these two are double ; 3, A single agglomeration of glandular lobules dispersed around the origin ‘of the small mesenteric and spermatic arteries: these are isolated from one another. These different masses receive the lymphatics of the pelvis, the emergent branches of the deep inguinal ganglia, those which come from the iliac ganglia, some ramuscules from the rectum and large colon, and those from the spermatic cord. They are bound to each other by communicating branches, and give rise to several series of emergent branches, which soon collect into one or more trunks that enter Pecquet’s reservoir. 2. Deep Inguinal Glands, This is a considerable mass of glandular lobules lodged beneath the aponeurosis and the crural arches, in the interstice of the adductor muscles of the leg, along with the crural vessels, within which they are placed. The form of this group is elongated, and its length may be six to eight inches, or even more; its superior extremity extends as high as the anterior border of the pubis. It is composed of from fifteen to twenty lobules, which rarely have an uniform colour, some being grey and OCIE, brown, or nearly black. The afferents are formed by the superficial lymphatics which accompany. the internal saphena vein, whose roots may be traced beyond the fetlock, and by the deep satellite vessels of the crural artery and vein. The efferents proceed to the sublumbar glands, by ascending in the abdomen along the external iliac artery and vein. 3. Superficial Inguinal Glands. These are placed in front of the inguinal ring, at the side of the sheath, on the track of the subcutaneous abdominal artery, where they form a small elongated mass from two and a-half to three inches in length, and are composed of a dozen principal lobules. Their afferents, which are very numerous, come from the inner aspect of the thighs, the sheath, scrotum, and the inferior abdominal wall, The efferent vessels, much larger, but less numerous—there are only five or six— ascend in the inguinal canal, accompanying the external pudic artery and — a 39 bi r’, NTS OF THE THORACIC DUC , 44 lk AFFLI “ASUOH FHL AO NALSAS OLLVHANAT AHL gl FPL PTO AIMGAIY IAG of [ For Description, see p. 640. 640 THE LYMPHATICS. ee. the inguinal nervous branches. They enter the deep inguinal glands, a , traversing the crural ring, in company with the prepubic artery, : SS 4, Popliteal Glands. Feit These glands represent a very small mass composed of from three to five independent lobules, situated behind the great sciatic nerve and gas- trocnemii muscles, between the long vastus and semitendinous mosclon aaa | near the femoro-popliteal artery. ss They receive some of the lymphatics which arise from the environs of - the hock, and those coming from the posterior and inferior part of the : | “ 3 4 4 gluteal region. Their efferents join the deep inguinal glands, by following | the muscular interstices of the thigh, - 5, Iliac Glands. ee Slightly yellow in colour, and of a soft consistence, these glands are five or six in number, and form a group which is situated in the triangular interval comprised between the two branches of the circumflex iliac artery. — They receive the emergent branches of the anterior crural glands, and a great number of deep lymphatics from the abdominal wall. Their efferent branches, four or five in number, follow the circumflex iliac artery to pass to the sublumbar glands. 6. Precrural Glands. Placed within the anterior border of the fascia lata, on the track of the circumflex iliac artery, these glands form a small elongated mass, composed of a dozen lobules lying close to each other. To this group come afferent vessels from the anterior and internal part of the thigh. It gives rise to — three or four large efferent vessels, which ascend the internal face of the — muscle of the fascia lata, accompanying the circumflex iliac artery, and __ entering the abdominal cavity near the angle of the haunch, to join the iliac — glands. LYMPHATICS OF THE ABDOMINAL VISCERA, 1. Glands and Lymphatic Vessels of the Rectum and Small Colon. The glands in this portion of the intestinal tube are: at first, two or three lobules placed at the base of the tail and on each side of the sphincter — ani; in the second place, a very numerous series of small glandular bodies situated along the small curvature of the viscus; thirdly, some rounded — A, Facial and nasal plexus whose branches pass to the subglossal glands; B, c, Parotid lymphatic gland, sending vessels to the pharyngeal gland; p, X, Large trunks passing towards the thorax; F, G, H, Glands receiving the superficial lymphatics of the neck, a portion of those of the limbs, and those of the pectoral parietes; 1, Junction of the jugulars; J, Axillary veins; K, Summit of anterior vena cava; L, Thoracic duct; — mM, Lymphatics of spl N, of stomach—o, of large colon—s, of small colon; R, Lac- teals of small intestine—all joining to form the two trunks, P, Q, which open di a into the receptaculum chyli; 1, Trunk which receives the branches of the sublumbar — glands, u, to which the vessels of the internal iliac glands, v, the receptacles of the lymphatics of the abdominal parietes, pass; W, Precrural glands receiving the lymph- atics of the posterior limb, and which arrive independently in the abdomen; X, Super- — ficial inguinal glands into which the lymphatics of the mamma, external generative organs, some superficial trunks of the posterior limb, ete., pass; z, Deep inguinal glands receiving the superficial lymphatics, 2, of the posterior limbs. q — we AFFLUENTS OF THE THORACIC DUCT. G41 lobules comprised within the two layers of the mesentery, and placed on the track of the arterial and venous divisions. _ Originating in the texture of the mucous and muscular tunics, the lymphatic radicles gain the glands of the small curvature of the colon, and escape from them as efferent branches, which pass in great numbers into the mesentery. These efferents, or at least some of them, traverse the lymphatic glands placed on the course of the blood-vessels, and collect, near the origin of the posterior mesenteric artery, into several somewhat voluminous branches, which join the divisions of the sublumbar glands, or those of the large colon. 2. Glands and Lymphatic Vessels of the Large Colon. There is seen on this enormous viscus a double chain of glands, lying _ beside the colic arteries, and numerous small lobules disseminated at a short distance from the principal glands, and on the track of the collateral branches furnished by these two vessels, Received at first, for the most part, by these lobular bodies, the lym- phaties which have emanated from the tunics of the viscus afterwards join the principal glands, from which they emerge in forming several large satellite branches for the colic vessels. Only two or three in number at the pelvic curvature, these branches are increased to ten or twelve on arriving near the origin of the colic arteries. It is from the union of these vessels with those of the small intestine, that the two large mesenteric trunks oi, Gh A, ©) arise, which, with the branches emanating from the sub- glands (Fig. 299, 8), form Pecquet’s reservoir. 8. Glands and Lymphatic Vessels of the Ceecum. There exists, on the track of cach cecal artery, a moniliform series of farther apart from one another than those of the double colic chain, to which the vessels coming from the cw#cal membranes are directed, and from which several long satellite branches of the blood-vessels, that proceed to the same trunk as those of the small intestine, depart. 4. Glands and Lymphatic Vessels of the Small Intestine. The glands which receive the lymphatic vessels from the small intestine are very large and abundant. About thirty in number, of a grey colour, very compact, fusiform, often bifurcated at their superior extremity, these are placed in the texture of the mesentery, near the origin of the great mesenteric artery, from which those belonging to the portion of intestine nearest the end of the viscus are most distant. The latter also in addition, fifteen special small glandular lobules, dispersed on the track of the ileo-cwcal artery. We have already noted the richness of the vascular apparatus which rises from the wall of the small intestine, towards the mesenteric glands. It must be added that these glands give rise, at their superior extremity, to large emergent branches, two or three for each, which soon coalesce to make more yoluminous branches that concur in the formation of the two intesti roots of Pecquet’s reservoir. 5. Glands and Lymphatic Vessels of the Stomach, There are two classes of lymphatic glands for the stomach: 1, Several large glands situated on the small curvature of the organ; 2, “< series of 27 642 THE LYMPHATICS. . small lobules disseminated along the great curvature to the attachment of the” t omentum. me: The vessels which emerge from them “gather on the track of the gastric arteries and veins, and ascend to the great tuberosity, near the trunk of the celiac artery ; there they anastomose with the lymphatics derived from the spleen and liver, and unite into several flexuous branches, some of which open directly into the thoracic duct, to which the others pass, after being confounded with the anterior trunk of the intestinal lymphaties.”—Colin. 6. Glands and Lymphatic Vessels of the Spleen and Liver. “Tho lymphatic vessels of the spleen, rising some from the interior of the viscus, others from its surface, pass towards the splenic artery and yéin ; they traverse several groups of glands disposed on the track of these vessels, commencing from the middle of the length of the fissure, ascend, five or six in number, towards the origin of the artery in forming a sinuous mass whose divisions, anastomosing with those of the stomach and liver, open, on the one hand, with the latter in the anterior trunk of the intestinal lymphatics, . 2 and, on the other, into a magnificent plexus communicating di y with ~ the thoracic duct. , “ Finally, the lymphatics of the liver form a very close network on surface, and another in the interior of the parenchyma. They collect towards the posterior fissure, and first dip into a primary and very small glandular group, then into a second group of voluminous round glands, which are concealed between the.trunk of the vena porte and the pancreas. They open in common with tho vessels of the stomach and spleen.”—Colin. GLANDS AND LYMPHATIC VESSELS OF THE ORGANS CONTAINED IN THE THORACIO CAVITY. We find annexed to these organs three groups of lymphatic glands: 1, A series of small granulations placed in the posterior mediastinum, on the course of the cesophagus ; 2, The bronchial glands, situated in the angle of bifurcation of the trachea, around the origin of the bronchi, which they follow for a short distance into the pulmonary parenchyma; 3, Two long strings of lobules extended on the sides of the inferior face of the trachea, — from the base of the heart to near the first rib. ~ Pe The first group receives the posterior lymphatics of the cesophagus, the second those of the lung, and the third those of the pericardium, heart, — and a portion of the trachea and cesophagus. Their efferents, uniting into some large trunks, enter the thoracic duct at different distances. GLANDS AND LYMPHATIO VESSELS OF THE THORACIC WALLS, re ; These glands form three series: 1, A double chain of rounded grains, situated on each side of the dorsal column, above the intercostal spaces, and beneath the costal pleura; 2, A frequently voluminous mass, lodged at the base of the xiphoid appendix, behind the heart, and in front of the inferior — part of the diaphragm ; 8, Some rudimentary granulations lying beside the internal thoracic vessels. The lymphatics of the diaphragm, after receiving those from the convex — face of the liver, pass to the glands placed at the base of the muscle, from which they escape in the form of several canals that accompany’ the internal thoracic vessels, and open into the anterior extremity of the thoracie AFFLUENTS OF THE THORACIC DUCT. 6k duct or the great lymphatic vein, the majority of them through the medium _ of the prepectoral glands. These vessels receive, on their course, those which are brought from the inferior part of the intercostal spaces into the suprasternal granulations. The other lymphatic vessels of the costal wall ascend between the two _ tauseles which close these spaces, and go to the subdorsal glands, which afterwards eject them, near the origin of the thoracic duct, in the form of _ one or two long vessels proceeding in a retrograde manner on each side of the dorsal column. LYMPHATIC VESSELS OF THE HEAD, NECK, AND ANTERIOR LIMB. These vessels are all directed towards the entrance to the chest, and are into a group of glands, called the prepectoral, which, with regard to the lymphatics of the anterior part of the body, play the same part as _ the sublumbar glands do to the vessels of the posterior region. Before arriving at this common point of convergence, they are inter- on their course by other glands, which form four principal groups: 1, The or pharyngeal glands ; 2, The submaxillary glands; 3, 'The glands ; 4, The brachial glands. ; In studying these different glandular groups in succession, with their afferent and efferent vessels, we will give a sufficient idea of the entire ; lymphatic apparatus in the region which remains for us to examine. ; a? & * a” 1. Prepectoral Glands.' They form, on each side of the terminal extremity of the jugular, within _ the inferior border of the scalenus muscle, a very large mass which extends into the chest by passing beneath the axillary vessels, and ascends to the _ inner face of the first rib. Into these glands pass the lymphatic vessels emerging from the pre- scapular and axillary glands, those which descend along the trachea with common carotid, and which come from the pharyngeal glands, as well as the majority of those which follow the internal thoracic vessels. They give rise to several short and voluminous branches: those from the glands of the right side form, by their junction, the great lymphatic _ vein; and those from the left side join the thoracic duct, or are inserted _ separately beside the latter, at the summit of the anterior vena cava. 2. Pharyngeal Glands, Very numerous, soft, and loosely united to one another, these glands are in an elongated mass that occupies the lateral plane of the pharynx, . >» the Taina pouch, and which is prolonged backwards even beyond ‘ ate ey all the lymphatics from the head: some come directly from the base of the tongue, the soft palate, the pharyngeal walls, and the larynx; the others are derived from the submaxillary glands, and from a Tobuile lodged in the substance of the parotid gland. _ ‘The efferent branches which leave it are four or five in number. _ Always voluminous, they descend along the trachea, some separately, but - the majority are united in a fasciculus which follows the carotid artery; 4 "These are glands, we believe, which ought to be regarded as the representatives of the axillary glands of Man. 273 644 THE LYMPHATICS, they are provided on their course with several elongated glands, to which the lymphatic radicles that arise from the cervical portion of the trachea and cesophagus pass, On arriving near the entrance to the chest, they are lost in the prepectoral glands. Some of them, however, traverse these without dividing, and directly enter, on the left, the thoracic duct, and on the right, the great lymphatic vein. It has been even possible for us to inject the latter vessel by one of these canals exposed on the right side, = 3. Submawillary or Subglossal Glands. oe They represent a fusiform mass situated at the bottom of the inter- maxillary space, in the receding angle comprised between the digastricus _ on the one side, and the mylo-hyoideus and subscapulo-hyoideus muscles on the other, above and near to the external maxillary artery, The lymphatics of the tongue, cheeks, lips, nostrils, and nasal cavities join these glands, Their efferents reach the pharyngeal or guttural glands, 4, Prescapular Glands. By their union they form a species of chain, at least twelve inches in length, placed on the course of the ascending branch of the inferior cervical artery, beneath the internal face of the levator humeri muscle, and descend- ing close by the fixed insertion of the sterno-maxillaris muscle. : The majority of the lymphatics of the neck, and those of the breast and shoulder, open into these glands. Their efferents, short and voluminous, enter the prepectoral glands, 5. Brachial Glands, ‘Situated beneath the anterior limb, within the arm, these vessels are divided into two groups: one placed near the ulnar articulation, within the inferior extremity of the humerus; the other disposed in a discoid mass behind the brachial vessels, near the common insertion of the adductor muscle of the arm and the great dorsal muscle, The first group receives the vessels from the foot and the fore-arm, which accompany the superficial veins, or pass with the deep arteries and veins into the muscular interstices. It sends nine or ten flexuous branches to the second group, into which open directly the lymphatics of the arm and shoulder, and from which emerge a certain number of efferents that pass, in company with the axillary vessels, to the prepectoral glands, ARTICLE III,—Great LyMpHATIO VEIN, The second large receptive trunk of the lymphatic vessels, this great vein (the ductus lymphaticus dexter) leaves the prepectoral glands of the right — side, and therefore becomes the general confluent of the lymphatics from the right anterior limb, the right axillary and superficial costal regions, as well as the right half of the head, neck, and diaphragm. This trunk is only from three-fourths of an inch to two inches in length. “Tt usually opens at the junction of the jugulars, at the side of the canal, by an orifice furnished with a double semilunar valve, Sometimes one or two of the branches which concur to form it describe circumvolutions around the corresponding brachial trunks or some of its divisions, before joining the others. Lastly, it is not rare to see this lymphatic trunk anastomose GREAT LYMPHATIC VEIN. 645 with the thoracic duct by voluminous collateral branches, then unite with it in such a way as to be inserted together by a single orifice above the gulf of the jugulars.”—Colin. Fig. 303, Fig. 304 , THE GREAT LYMPHATIC VEIN AND ENTRANCE OF THE THORACIC DUCT, A, Thoracic duct ; B, Great lymphatic vein, or right lymphatic trunk ; c, p, Anasto- moses established between them near their insertion. DIFFERENTIAL CHARACTERS IN THE LYMPHATIC SYSTEM OF OTHER THAN SOLIPED ANIMALS, The lymphatic system, glands and vessels, is more developed in Ruminants and the Pig than in the Carnivora, In this respect the domesticated animals may be classified in the following order: Oz, Sheep, Horse, Pig, Dog, Cat, Rominants.—“ The thoracic duct of large Ruminants, when it has entered the thorax by a special opening in the diaphragm, almost distinct from that of the aortic arch, is placed above and to the right of the aorta, between it and the spine. There. although outside the corresponding intercostal arteries, it is completely concealed by a thick layer of adipose tissue, in which are numerous subdorsal glands. Towards the fifth dorsal vertebra, it receives a large lymphatic vessel coming from the enormous gland that exists on the track of the cesephagus in the posterior mediastinum; it then crosses the direc- tion of the aorta and the cesophagus, passes to the left, gains the entrance to the thorax, and opens in front of the first rib, above the junction of the left jugular with the anterior vena cava." . “ The varieties it presents in the Ox are numerous and very common. The rarest disposition is that of a canal, single through- ia out its entire length, such as it has been Fig. 305. described, and such as it is usually found to be in small ruminants (Fig. 309). This eanal (Fig. 306), single at its origin and for the greater partof its extent, often bifur- cates towards the base of the heart, or ata short distance from its insertion. Of these two branches, one passes to the right of the j@sophagus and trachea, the other to the left of these, in following the ordinary direction ; and, at the entrance to the thorax, they either terminate separately, each in tlie angle of union of the jugular and corresponding axil- ENTRANCE OF THE THORACIC DUCT IN lary vein, or together at the same point—the THE OX, : gulf of the two jugular veins. “Tt happens that one of the branches of the bifurcated canal is in its turn subdivided into two smaller branches, and that the other experiences at the same time a similar (* Zundel has pointed out the curious fact, that in Ruminants, the long, special, lymphatic gland situated between the layers of the mediastinum and above the cesopha- gus, sometimes becomes so voluminous that its weight impedes rumination, especially when the animal is lying. The bolus of food is prevented from ascending into the cesophagus, and this may become a frequent and periodic cause of indigestion.) 646 THE LYMPHATICS. subdivision : in such a way that the trunk of the canal, at first single; becomes double, then quidruple, and eomsequeutly opens into the yeuous system by four distinct orifices. Fig. 306, Fig. 308, VARIETIES OF THE THORACIC DUCT IN THE OX, If the branches of the canal, instead of remaining isolated, send olf transverse anastomoses, there results a complication of which Solipeds do not offer an example (Fig. 305), - The thoracic duct is often double throughout its extent. The two canals are then THE CIRCULATORY APPARATUS OF BIRDS. 647 detached separately from the cistern, one follows the right side, the other the left side of the aorta, describing an arch whose concavity is downward at the base of the heart, on the lateral parts of the trachea, terminating either very near one another, and on the same transversal line, at the junction of the two jugulars, or one to the right, the other to the left, in exch of these two veins, and not far from their junction with the axillaries (Fig. 307.) *“ When the two canals arise from the sublumbar reservoir, they sometimes repeatedly anastomose with each other by sinuous and curved branches, as shown in figure 308. Fig. B09. THORACIC DUCT OF SMALL RUMINANTS, * Then all the branches collect in the anterior mediastinum, and constitute a single canal which, near its termination, again subdivides into four vessels that open separately, two to the riglit and two to the left, in the usual place. “This variety is tlie most remarkable and complicated of all those observed in the domesticated animals. Pig.—* The thoracic duct of the Pig, usually single throughout its whole extent, is sometimes divided, at one to one and a-half inclies from its insertion, into two branches which soon reunite in an oval dilatation ; this, after receiving the vessels from the head, neck, and limbs, opens towards the extremity of the left jugular. Carnivora In the Dog, Pecquet’s reservoir is enormous; in shape it is ovoid, and is prolonged between the pillars of the diaphragm into the thoracic cavity. The thoracic duct of this animal generally resembles that of the Pig. Yet it sometimes offers in its course and termination very numerous variations: Rudbecky has noticed a bifurcation above the heart, and another bifurcation whose branches anastomose with each other several times. Swammerdam and Stenon have figured numerous irregular anastomotic divisions towards the middle of a single canal, to its point of departure. ‘These old authors have indicated and represented double and triple insertions of different forms. Lastly, Bilsius has shown an arch, or rather a very remarkable ring, at the entrance of the conduit, and at its junction with the lymphatic vessels of the neck and anterior limbs, and which is more or less analogous to that which I have observed on several occasions in the Horse, Pig, and Cat.,’” CHAPTER IIT. THE CIRCULATORY APPARATUS OF BIRDS, WE will briefly examine the characteristics of the different portions of the circulatory apparatus—the heart, blood-vessels, and lymphatic vessels—of birds. Articie I.—Tue Heart, The heart, in birds, is situated quite at the entrance to the chest, in the median line, and is contained in a pericardium that adheres to the posterior diaphragmatic septim 1 G., Colin, op. cit. 648 THE CIRCULATORY APPARATUS OF BIRDS. and the cervical reservoir. In the domesticated species, it has the form of an acute cone, whose base is surmounted by a less distinct auricular niass than in the Mammalia. Internally it has four cavities. The right ventricle is more crescent-shaped than in Solipeds, and in a manner envelops the left ventricle in front and to the right; it does not reach the point of the heart. The auricular valve is not tricuspid, and offers a very remarkable arrangement. “This valve, in fact, instead of being formed as usual by membranous curtains whose margin is retained by cords fixed to the walls of the ventricles, is composed of a wide muscular leaf which appears to be a of the inner wall of the ventricle detached from the interventricular septum. is septum is convex, and the auriculo-ventricular orifice is situated in the space comprised between it and the muscular valve in question; so that when the latter contracts at the systole, it is applied against this septum and closes the passage.” * ‘ There is nothing particular to note with regard to the left ventricle, whose walls are likewise thicker than those of the right. The auricles have a kind of diverticulum or sinus, in which the veins that open into each of these cavities unite. ArticLe II.—Tae ARTERIES, The aorta of Gallinaceous birds ascends beneath the lower face of the right lung, then turns abruptly. backwards and a little to the left. It attains the median line towards the anterior extremity of the kidneys, and in this situation it reaches the sacral vertebra, mers it divides into three branches—the arteries of the pelvic limbs, and the middle sacral artery. Ser Close to its origin, the aorta gives off the potas tir pr (or innominate a With the Fowl this name is perfectly correct, as they both furnish vessels to wings and head. The right passes upwards and forwards, is inflected backwards at the first rib, and continued on the lower face of the wing by the humeral artery. It throws off a thoracic artery, whose yolume is in relation with that of the pectoral muscles; this emits superficial branches that form in the skin of the abdomen, with other vessels, a very rich plexus named by Barkow the rete mirabile ofincubation. It afterwards gives off a cephalic trunk, from which arise the ascending cervical, vertebral, and right carotid artery. ‘The left brachio-cephalic trunk has the same distribution as the right, a slight difference only being observed in its direction ; on leaving the thoracic cavity it Pete a small § curvature. The carotid arteries exhibit a somewhat curious arrangement, Each springs from a corresponding brachial trunk; and placed at first on the sides of the neck they make a curve, whose convexity is anterior, and gain the median line by passing, the right above the esophagus, the left above the trachea. They remain beside each other, beneath the longus colli, from the second last to the second cervical vertebra, where they separate at anacute angleand reach the border of the jaw, terminating there in two branches—the internal and external carotid arteries. The other collateral branches furnished by it, are: 1, The intercostal arteries. These may arise from the subcostal branches which are parallel to the aorta; thus, in the Foul, there is a common descending intercostal which proceeds from the vertebral, and a common ascending intercostal that leaves the aorta as it passes into the abdomen; 2, The celiac trunk, which commences at the middle of the lower face of the lung, and descend- ing obliquely backward, reaches the posterior t of the liver. It divides into several ramuscules, of which there are three principal vessels: a very fine one goes to the spleen; a left or middle one passes to the gizzard along the proventriculus; the th more voluminous, is directed to the right side, gives a twig to the liver, and is contin by a long pancreatico-duodenal branch that joins the extremity of the loop which the intestine forms at its origin; 3, The anterior or swperior mesenteric, which arises at a short distance behind the coeliac trunk, enters the mesentery, and is directed ba describing a curve whose convexity is antero-inferior, and which emits twigs to the intestine; 4, The spermatic or ovarian arteries. The inferior or posterior mesenteric leaves the subsacral artery, and, by some ramuscules, reaches the rectum and cloaca, Shortly before its termination in three branches, the aorta gives off an artery that crosses the middle portion of the kidneys, leaves the abdominal cavity, and becomes dis- tributed to the anterior muscles of the thigh, after detaching the epigastric artery. The latter proceeds forward, beneath the skin of the abdomen, and anastomoses with the ramifications of the thoracic artery. 7 , ' Milne Edwards— Legons sur la Physiologie et l’Anatomie Comparée de Homme ; et des Animaux,’ Vol. iii. THE CIRCULATORY APPARATUS OF BIRDS. 649 of the pelvic limbs—the femoral or crural, in passing above the kidneys, renal arteries; they then leave the pelvis by the great ischiatic notch, im- behind the coxo-femoral articulation. Placed beneath the muscles on the osterior of the thigh, in following the branches of the lumbo-sacral plexus as far femoro-tibial articulation, they are then continued by the popliteal vessels. These throw off articular ramuscules, the medullary artery of the tibia, and a long to the muscles on the posterior aspect of the leg; they are placed in the groove g¢ from the junction of the tibia and fibula, and pass through the osseous inter- to form the anterior tibial arteries. The middle sacral continues the aorta to the bottom of the pelvis; when it arrives below the last coceygeal vertebra, it forms a kind of arch whose ramifications are dis- - tributed among the muscles and quills of the tail, i Hay Articie I[],—Tue Vers, As in Mammals, the veins are distinguished as belonging to the great and lesser circulation. The veins of the great circulation are collected into three trunks that open into the t auricle of the heart; there are two anterior venz cave and one posterior vena cava, enter a particular compartment, a kind of sinus, in the auricle. __ anterior venz cavex collect the blood from the subclavian arteries and those of the head. The jugular veins, which are their principal branches, are not the satellites of the carotid arteries. as in the larger domesticated animals; they are superficial and a on the sides of the trachea; while the carotids are placed in the median line th the long flexor muscle of the neck. They are not of the same calibre in all species, the right jugular being more voluminous than the left ; there is always, however, a transverse anastomosis between the two jugulars, below the base of the cranium. The posterior or inferior vena cava commences at the anterior extremity of the kidneys, and passes forwards, traversing the right portion of the liver, receiving the hepatic veins, and enters the right auricle. Among the branches forming it, there may be cited the femoral or crural veins. These vessels do not accompany the corresponding arteries; not entering the pelvic cavity by the great ischiatic notch, they pursue a course analogous to that described for these vessels in Solipeds, in passing beneath the crural arch. In birds furnished with a crest and mandibles, the skin of the head is provided with an excessively rich vascular plexus, Articyue IV.—Txe LymMpuHatics, Birds possess et vessels and glands, The latter are few, and are scarcely met with elsewhere than in the cervical region ; the former are abundant in the viscera, and unite in such a manner as to form two thoracic ducts. These ducts commence at the trunk, eet pom along the lower face of the lung, receiving the lymphaties of that and those of the wings, and finally open into the jugular veins, a little in front of with the axillary veins. A transverse ch forms a communication between the two thoracic ducts, towards their termination. E BOOK VI. APPARATUS OF INNERVATION, soe FIRST SECTION. THE NERVOUS SYSTEM IN GENERAL, Tue functions whose instruments we have just described, suffice in them- selves to maintain nutrition —that mysterious molecular movement which is the ultimate object of the activity of organs, and the essence even of life: loco- motory acts which permit the animal to seek its food and to introduce it into its organism, lead to the elaboration and absorption of the assimilable materials of the alimentary mass in the interior of the digestive cavity, the circulation of the reparative fluids in the economy, and the depuration and revivification of these fluids by the action of the lungs and the kidneys: in brief, could anything more be required to constitute the conditions necessary for the manifestation of the nutritive phenomena ? And yet, while the anatomist conceives in his mind a vertebrate animal exclusively endowed with the apparatus destined to execute these functions ; while he supposes the breath of life and the dependent properties of that animating principle to be due to these apparatus, he could not succeed in creating an imaginary being capable of moving, digesting, keeping in cireula- tion the nutritive fluids, reviving these fluids by respiration and urinary depu- ration—in a word, of executing all those acts whose concurrence is indimgeule able to the maintenance of nutrition, the supreme vital act. It is because the tissues of that animal, though possessing the organic properties inherent in their structure, require an excitant capable of bringing these properties into play. Their inertia is due to the absence of this excitant; for all motion, no matter what kind it may be, demands for its realisation, not only the motor faculty in the organ which executes it, but also an excitatory cause. But give to this mutilated organism, this creation of our fancy, white cords, ramifying by extremely slender divisions in the depth of these instruments of life, and commencing from a central axis lodged in the cranium and spinal canal; or, in other words, add to our incomplete animal an apparatus of innervation, and, as if by enchantment, there will appear the first signs of life. Owing to the peculiar properties which dis- tinguish the tissues of this apparatus, and concerning which we will have more to say hereafter, it plays the part of an excitor and regulator with ee . to the properties of the other tissues. Stimulated by the nervous system, these properties no longer remain in a latent state, but manifest themselves by ‘their usual results—such as contraction in the muscles, and exhalation and secretion in the membranes and glands; then the imperfect being at once begins to digest, respire, ete.—in a word, to live, and is worthy of — taking rank in the animated world. THE NERVOUS SYSTEM IN GENERAL. 651 But the effects of this ‘radical transformation do not cease here. ‘The animal thus rendered apt to the nutritive movement acquires, beyond this vegetative life, the common appanage of all organised beings, all the attributes of what it has become habitual, after Bichat, to term animal life,—that is, sensibility, volition, instinct, and intelligence. _ The perceptive centre which receives the excitations developed at the periphery of organs, or in their structure; the excitatory centre which induces motion in all the other tissues; the seat of the instinctive and intellectual faculties ; in short, does not the apparatus of innervation, thus charged with the grandest physiological finality, present itself as a most attractive study ? We will commence by giving a general and succinct idea of its conformation, structure, properties, and functions, before undertaking the special description of the different parts composing it. ’ GENERAL CONFORMATION OF THE NERVOUS SYSTEM, The apparatus of innervation comprises a central and a peripheral rtion. 2 The first represents a very elongated stalk lodged in the spinal canal, and bulging at its anterior extremity, which occupies the cranial cavity. This is named the cerebro-spinal axis or centre. The second consists of a double series of ramescent branches, which are given off laterally from the central stalk, to be distributed to all parts of the body ; these branches are the nerves. Tue Cerrepro-spinaL Axis.—The stalk, or azis properly so called, lodged in the spinal canul, forms the spinal marrow (or cord). It is a large white cord, terminating in a point at its posterior extremity, and giving rise, at each intervertebral foramen, to one of those nervous branches which, collec- tively, represent the peripheral portion of the apparatus of innervation. The bulging extremity inclosed in the cranium, is named the encephalon (or brain). More complicated in its conformation than the spinal cord, this portion is divided, as we will see, into four parts: 1, A white peduncle, the continuation of the spinal cord; 2, Three grey-coloured ovoid masses, one of which is posterior, the other two being anterior, and placed symmetrically side by side. This medullary prolongation emits, right and left, like the cord itself, nervous branches destined almost exclusively for the head. Tue Nerves.—The nerves are in the form of fasciculated cords, and make their exit from the orifices at the base of the cranium, or through the intervertebral foramina, passing into all the organs by ramifying like arteries, which they generally accompany. All the nerves have their origin from the medullary axis, or from its oe Tg prolongation, by radicles more or less apparent. ‘They are divided, according to the relative position of their point of emergence, into two great categories ; the superior, arising from the corresponding face of the spinal axis ; the others, inferior, escaping from the lower face: a distine- tion which is perfectly appreciable with regard to the cord itself, but which is more difficult to establish in the encephalic peduncle, as it is less distinct. At their emergence from the bony canals which give them passage, the radicles of each nerve always unite into a thick common trunk. In the majority of cases, there enters into the composition of this trunk the nerves or fibres of the two orders; only a few nerves are composed of fibres of the one kind, and these all belong to the brain. “a = etw £ ' 652 THE NERVOUS SYSTEM IN GENERAL. At the origin of the trunk into which the nerve roots are collected, there is a greyish enlargement termed a ganglion; but this peculiarity belongs exclusively to the superior fibres. wo8 After a variable course, which is generally short, this trunk divides into branches, the point of departure for all the nerves of the body. Among these branches, those which are expended in the apparatus of animal life are pairs, and perfectly alike on both sides of the body. Those of the of nutrition are composed at first of an almost symmetrical double chain, placed beneath the spinal column, and whose elements are borrowed from nearly all the nervous trunks emanating from the cerebro-spinal axis; in proceeding to their destination, their distribution is most irregularly com- plicated. As they offer on their course a great number of ganglia similar to those we have already mentioned, they are called ganglionic nerves ; they are also designated the nerves of organic or vegetative life, while the others are named the nerves of animal life or of relation. STRUCTURE OF THE NERVOUS SYSTEM. Two particular substances, one grey, the other white, enter into the organisation of the nervous apparatus. These two substances are formed, the first by nerve-tubes and united nerve-cells; the second by tubes alone. The nerve-tubes are microscopic elements, composed of a proper wall and contents. The wall, named the nervous sheath (sheath of Schwann), is a thin, homogeneous, elastic membrane that contains in its substance or its inner face some nuclei of cells. It is not visible in quite fresh tubes. The contents i comprise, in the centre, a solid core, the axis-cylinder Pie 82% (or primitive band of Remak), which becomes very appa- rent after the addition of certain reagents; between the axis-cylinder and the wall is found a viscid substance, the nervous medulla or white substance of Schwann, which coagulates very quickly under the influence of cold. When the medulla is solidified, it is seen to be bordered by two dark lines, parallel to the walls of the nerve-tubes; this aspect has caused the latter to be named “ double-contoured tubes (or nerve-fibres).” pena or Snuc- _ All the nerve-tubes do not possess, at the same time, baa *VE these three parts, for the medulla may be absent ; so that 1. Sheath: 2, Medul- there are distinguished medullated and non-~medullated "lary substance of nerve-fibres. The first, more or less thick, are met with Schwann; 3, Axis- in the nervous centres, and at the origin, and in the cylinder, or primi- middle portion of the nerves; the second are found at Ere Pew the termination of nerves, and in the great sympathetic. There are also observed in the nerves of organic life, elongated elements, designated fibres of Remak, grey fibres, and nucleated nervous fibres. These are pale, flattened fibres, with parallel borders, and furnished with elliptical nuclei. Some authorities consider these to be bands of connective tissue, and not nerve elements. The nerve-cells, or corpuscles, are voluminous, and are formed by a mass of granular protoplasm without any enveloping membrane. In the ganglia they are covered by a layer of fibrous connective tissue, provided with nuclei, which appear to furnish them with a very thick enveloping membrane. The nucleus, with one or two nucleoli, is often surrounded by granulations, whose dark colour gives rise to the supposition that they are pigment cells, THE NERVOUS SYSTEM IN GENERAL. 653 - - The nerve-cells have prolongations or poles, whose number varies from one to five. Cells with only one prolongation are named unipolar; those which have two are bipolar; and those which have a greater number are designa- ted multipolar. These poles establish relations with the nerve-tubes, and constitute the origin of the nerves. Fig. 311. MULTIPOLAR OR STELLATE GANGLIONIC NERVE-CELL, WITH ONE OF ITS PROLONGATIONS— a, Becoming continuous with the axis-cylinder of a double-contoured nerve-fibre, b. Such are the anatomical elements that enter into the structure of the nervous system. In the white substance of the cerebro-spinal axis, only medullated nerve- tubes of every size are found; in the grey substance are tubes, and a more or less iderable number of nerve-cells are situated along their course. To these two elements is added a large quantity of blood-vessels, which are incomparably more abundant in the grey than in the white substance. In the nervous cords, the elementary tubes are alone met with; they are disposed in long bundles, which are collected into successively increasing fasciculi. A cellulo-vascular envelope, the neurilemma (or perineurium), binds all these fasciculi into a single cord, and forms a special sheath around each of them. The details of their organisation will be referred to hereafter. It is admitted that the ganglionic, or nerves of organic life, possess a greater quantity of slender tubes than the others, These tubes are com- _ monly designated as the organic nerve fibres. They also contain fibres of In the ganglia, the cells are joined to the nerve-tubes, It has been shown, dissection and microscopical observation, that the corpuscles composing ia at the origin of the trunks aro all attached to the superior fibres. The other tubes have none. In the cerebro-spinal axis, the two substances are equally associated with each other, but in a variable manner, according to the region. In the cord 654 THE NERVOUS SYSTEM IN GENERAL. and its prolongation into the encephalon, the grey substance occupies the interior, while it is spread over the exterior of the encephalic lobes and envelops the white substance. Fig. 312. Figs 815, MICROSCOPIC GANGLION FROM HEART BIPOLAR GANGLIONIC CELLS AND NERVE- OF FROG, FIBRES, FROM GANGLION OF FIFTH PAIR IN LAMPREY, (In some instances, as in the cells of various parts of the spinal cord, the prolongations subdivide and ramify in a curious manner, and form a close network that penetrates the surrounding nervous tissue. In addition to these, there are other very complex nerve-cells whose structure has only Fig. 314. . 8LELLATE NERVE-CELL, FROM THE NUCLEUS CERVICIS CORNU (POS- TERIOR VESICULAR COLUMN) OF A FETUS OF SIX MONTHS. MAGNIFIED 420 DIAMETERS. STRUCTURE OF GANGLIONIC NERVE-CELL, A, According to Beale; B, According to Arnold.—a, Straight fibre; 6, Double _ spiral fibre; c, Capsule of connective tissue. recently been clearly established. These have been found in the sympathetic ganglia, and each is invested in a capsule of connective tissue. In shape, the cell is pyriform, and it contains a nucleus; from the narrow end spring two fibres, that pass in opposite directions when they reach the nervous THE NERVOUS SYSTEM IN GENERAL. 655 bundle to which they are distributed. This disposition has given rise to the opinion that every nerve-fibre, no matter how long its course may be, is a loop that originates in, and returns to, the same cell. One of the fibres that enters the cell, and looks like a stalk to it, is usually straight; the other - seems to arise from the outside of the cell, is sometimes double, and circles round the other in a spiral manner two or three times. Both fibres at first resemble the cylinder-axis of ordinary nerve-fibres, and may subsequently be- come dark-bordered, or remain pale fibres. The spiral fibres bear large oblong nuclei in their course. Some observers state that they have traced the straight fibre into the nucleus, and the spiral fibre into a plexus on the exterior of the cell, but which may be ultimately traced into the nucleolus ; so that the two fibres are continuous through the nucleus and nucleolus). . PROPERTIES AND FUNCTIONS OF THE NERVOUS SYSTEM. It would require a long chapter to do justice to this subject, and we could not venture on it here without going beyond our domain. We will, however, offer some remarks on those notions connected with the properties and functions of the nervous system which are strictly necessary for the comprehension of the anatomical facts to be hereafter dealt with. And first as to the properties of the nerves. __ We will suppose the spinal canal to be opened in the lumbar region, and the cord laid bare in a living animal. If we cut across the inferior roots of one of the spinal nerves, and if we compress with a pair of forceps one or more of these roots, by the end remaining attached to the cord, nothing results to denote that this irritation has had any influence on the organism. But if, instead of operating on the central or attached end of these divided roots, we excite the peripheral end which is continued by the trunk of the nerve, contraction of the muscles of the limb which receives the fibres coming from the irritated roots is produced, The muscular tissue comports itself as if the irritation were directly applied to it; so that the nerve has served as the medium of communication. It has received the excitation, it has been impressioned by it, and it has conducted this to the muscles to which the nerve is distributed. This double reaction produced by the nervous tubes is their special attribute, their essential property. With M. Vulpian we might designate it as a whole by the name of neurility ; but it is necessary to distinguish the two modes it afiects by naming the property of being impressed by excitations as the excitability of the nerve, and nervous conductibility its aptitude to convey the excitations which have impressed it. The same experiment may be repeated on the upper roots, It is then perceived that the pinching, which produces no effect at the peripheral extremity, causes pain when applied to the central end. The animal testifies immediately, by cries and movements, that it feels the touch of the forceps. But, as will be mentioned in a moment, the impression resulting from this touch has only been perceived by the brain; it has therefore been conducted to the spinal cord by the excited nervous fibres, and then to the brain by the fibres of this medullary axis. Tn putting to one side, for the moment, the part played by the latter in the phenomenon now analysed, it will be seen that the superior fibres of the spinal nerves enjoy the same attributes as the inferior; neurility is their appanage, and this property is apparent in its two qualities—ewcitability and couductibility, Only here the latter property is exercised in a centripetal 656 THE NERVOUS SYSTEM IN GENERAL, sense ; while in the first instance it acted in a centrifugal sense. But it must not be assumed that these two conductibilities are essentially distinct. ‘The physiological differences by which they appear to be distinguished seem to belong to the difference in the relations of the nerve-fibres with the to which they are distributed. In one case, that of the centrifugal nerves, the organs of reaction—the muscles—are placed at the peripheral extremity of the nerves; in the case of the centripetal nerves, the organs of reaction— the brain and spinal cord—are found at the central extremity of the nervous — fibres. This theory of the unity of nervous conductibility has, moreover, been proved to be correct by the researches of Philipeaux and Vulpian, who have utilised the experiment of Gluge and Thiernesse on the union of the central end of the lingual (centripetal) with the peripheral end of the hypoglossal nerve (centrifugal), to demonstrate that the fibres of the former then acquire centrifugal conductibility. It is easy to demonstrate that this double property of conduction belongs to all the nerve-fibres springing from the cerebro-spinal axis, centripetal conductibility being peculiar to the superior fibres, and centrifugal ucti~ bility to the inferior ones. It is also demonstrated that this conduction acts in either one sense or the other, whatever may be the point on the course of the nerves’ so stimulated ; as the nerve-tubes possess, throughout their whole length, the property of excitability and conductibility, The fibres with centrifugal conductibility constitute the motor nerves ; those whose conductibility is centripetal are the sensitive nerves. But sensi- bility does not exist only in the filaments of the superior roots; it has also been remarked in the lower roots, and they owe it to the filaments which are given off from the roots whose conductibility is centripetal, and which return to the nervous centres by the motor roots. The sensitiveness evinced by these motor roots is named recurrent sensibility. The anatomical and physiological characters of the nerves persist as long as they communicate with the centres. If they are divided at any part of their course, the portion attached to the spinal axis still preserves its properties; but that situated beyond the section—the peripheral end, as it is named—degenerates, and becomes incapable of conducting the sensitive impressions, or of transmitting the voluntary motor excitations, Now as to the spinal cord. Does the medullary axis, which has apparently, in great part, the structure of a nerve, possess, like the latter, excitability and conductibility, those two essential properties of the peripheral nervous system ? Excitability is entirely absent in the grey substance. On the surface of a section of the cord, the slightest, or even the most intense irritation of this portion produces no reaction. In the white substance, this excitability can only be easily rendered evident on the surface of the upper bundles or fasciculi, where it is exquisite. With regard to the always limited reactions observed when the excitations are made on the deep part of the fasciculi, it is difficult to say if they result from the excitability of the spinal cord, or that of the nerve roots that traverse the white substance. Nervous conductibility is certainly one of the attributes of the spinal cord; the transmission of excitations of the sensitive nerves to the brain, and the voluntary movements that result from stimulation of the motor nerves, demonstrate that the necessary medium between the nerves and brain—the spinal cord—possesses conductibility. But does this portion of the nervous system possess no other property? Yes; it may act as a nervous centre, and the following experiment irrefutably demonstrates it : :~.= THE NERVOUS SYSTEM IN GENERAL. 657 TI will suppose that an animal has had its spinal cord cut across in the lumbar region, and I excite, by pinching, one of the superior roots re- maining intact on the caudal portion. The stimulus cannot be conducted to the brain, as this part is isolated from it; and yet movements take place in the muscles of the posterior members. Does it happen that, after section of the medulla, the conductive property of the nervous fibres which originate _ superiorly is interverted and changed into centrifugal conductibility? No: _ for after the transvexse section of these roots, the irritation of their central end produces exactly the same effects. It must be, therefore, that the excitation had first reached the medulla, and was then transmitted by it to _ the muscles by means of the centrifugal current fibres. And this is really _ what oceurred ; the section of the whole of these fibres on the trunk of the cord hindered the manifestation of all movement in the muscles when the superior roots were touched. ‘There is, as has been said, reflexion in the substance of the cord, on to the inferior roots, from the irritation due to this pinching, and the property which permits the medullary axis to act in this manner is named the reflex power. It may be remarked that, if we suppose for a moment the superior and inferior nervous roots to be united in an arch in the substance of the spinal cord, this reflex property would be nothing more than the nervous conductibility itself operating precisely in the direction special to each kind of nerves. This union really takes place; only the nerve-roots are not in communi- eation, except through the medium of the cells in the grey substance, in which the sensitive is changed into motor excitation. ' ~ The reflex power is extinct immediately after death occurs in Mammals, _ but it may last for several hours, or even for a day, in a decapitated animal in which asphyxia has been averted by pulmonary insufflation. The extent of the movements it determines is in relation to the intensity of the stimulus which is the primary cause of it; merely localised when they result from a slight irritation, these movements may take place in all the muscles of the body after an energetic stimulation. Let us now inquire into the attributes of the encephalon. Excitability is not remarked in all parts of the brain; it exists in several points of the medulla oblongata, and in the deep substance of the cerebellum; but it cannot be rendered evident on the surface of the latter, nor yet in the cerebral hemispheres. The brain possesses conductibility, because the grey substance composing it is the receiver of, and the point of departure for, all the excitations. In fine, the encephalic mass should possess neurility like the nerves, but this general property is more or less modified. What more particularly distinguishes the encephalon is its action a8 a sensitivo-motor centre; in it arrive the excitations from the sensitive nerves, and there they are felt and judged. In the brain arise the motor excitations which result in spontaneous voluntary movements. Im an animal paralysed by division of the cord at the occipito-atloid articulation, and in which death has been prevented by artificial respiration, ‘observation demonstrates that sensibility and spontaneous motricity are ‘preserved in the head, whose nerves are in direct communication with the encephalon. Pinch the upper lip, and the patient testifies by the movements of this organ that it feels pain. Pass the finger towards the eye, and the eyelids are twinkled and closed: a proof that the animal sees objects, ors the distance which separates it from them, and tries to remove eye from their contact. More striking still, the animal feels hungry, and endeavours to satisfy this craving by seizing the food within its reach, and 2u 658 THE NERVOUS SYSTEM IN GENERAL, masticating and swallowing it. After this demonstration, it is no Lee possible to doubt that, if an animal feels, it is by the brain, and if it wills, itis — r also by the brain. Bo But sensibility and volition do not constitute the only attributes of the — brain tissue; for it is the seat of other manifestations not less interesting— those of the instincts and intelligence. _ If the encephalon is to be considered as the immediate instrument of all these phenomena, it would be impossible—it is impossjble—to attribute the cause, properly speaking, to the activity of its physical matter ; above this a hovers a mysterious power that can only be demonstrated by a methodical analysis of the manifestations produced by that activity. But we dare not venture to touch upon the nature of this power; the first word hie i useless without the last, and this would carry us too far. To sum up, the nerves possess a single vital property—neurility, which a is manifested by excitability and by centripetal conductibility in the nerves: whose roots are uppermost, centrifugal conductibility in the nerves whose — roots are inferior. The spinal cord is inexcitable in its grey substance, but is excitable on — the surface of its superior fasciculi, though scarcely so in the remainder of its white substance. It serves as the organ of transmission between the brain _ and bax nerve-roots ; and i is, in addition, endowed with the reflex property or _ “4 a 3 The brain has for its appanage a special activity, to which is due sensi- bility, volition, and the manifestations of instinct and intelligence. = It remains to make known the nature of the influence the nervous system - exercises on the other apparatus through the properties we know it to © possess. But here again we must limit ourselves to principles, Since Bichat’s time, it has been agreed to divide into two great classes those functions whose operation maintains the life proper of the individual: _ those of animal life or relation, and those of organic or vegetative life. : The first, which are exercised with consciousness, comprise the sensorial functions and voluntary movements; the latter are provoked by the spon- taneous excitation originating in the brain, and transmitted to the muscles — by the nerve-fibres whose’ conductibility is centrifugal; the former have for their object the appreciation, by the brain, of tactile sensations —of heat, light, taste, and smell, by means, or through the instrumentality, of the nerve-fibres possessed ‘of centripetal conductibility, which transmits to the — encephalic mass the stimulus developed at their terminal extremity by these diverse physical agents. 4 The functions of vegetative life—those which are executed unconsciously, : we may say, in animals, and which are not the result of physico-chemical forces—are placed under the influence of the reflex power of the spinal cord. - For example, the stomach is empty and its mucous and muscular membranes — remain altogether passive; there being no contractions in the first, nor secretion of gastric fluid in the second. Food arrives in its interior, and immediately its activity is developed; the muscular tunic executes move- ments which cause the mixture of the food, and propel it towards the pyloric orifice; while the free surface of the internal membrane pours out. an abundant solvent secretion. This change is due to the stimulus exercised by the presence of. the alimentary particles on the extremity of the centri petal nerve-fibres, and which has been transmitted by them to the medul- lary axis, there reflected on the centrifugal fibres, and carried by these to the tunics of the stomach, whose special functions are thus brought into play. — THE CEREBRO-SPINAL AXIS, 659 It is worthy of remark that the properties of the nervous system, which ct in so important a manner on the organs of vegetative life, have no direct influence on nutrition itself. Destruction of the nerves in a certain ae gion will certainly derange the nutrition of its tissues, in consequence of _ the paralysis of the vessels, but it is not destroyed. There is an immense ‘ ry of organised beings—vegetables, for instance—in which nutrition _ 4s very active, and in which there is no nervous system. So that the ‘ . “THE ENVELOPING AND PROTECTING PARTS OF THE CEREBRO-SPINAL : Bs. AXIS. Tue cerebro-spinal apparatus is lodged, as we already know, in a bony case —the spinal canal—which is prolonged anteriorly by the cranial cavity ; but it is protected more immediately by three envelopes, which have received the names of dura mater, arachnoid, and pia mater. 2h THE BONY CASE THAT CONTAINS THE CEREBRO-SPINAL AXIS, A knowledge of the bones which enter into the composition of this pro- tective case, cannot be acquired without also knowing the case itself; so that we dispense with its special study here. We will allude, however, to ‘the succinct terms already employed in describing the spinal canal, and in the same spirit of concision will also describe what has hitherto been _ deferred—the cranial cavity. - 1. The Spinal Canal, _ This canal communicates, anteriorly, with the cavity of the cranium. iecr wide at the atlas to receive the odontoid process, and allow those rotatory movements of the head which prevent the medulla being injured, the spinal canal suddenly contracts at the axis ; it expands again at the end _ of the cervical, and the commencement of the dorsal region, where the medulla presents a greater volume, and the movements of the spine are very - extensive. Towards the middle of the back, the spinal canal offers its ‘smallest diameter, but on leaving this portion, and as far as the ey sia 2u 660 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. articulation, it widens again; after which it rapidly lessens, and altogether disappears towards the fourth or fifth coceygeal vertebra. The lumbo- ‘ sacral dilatation coincides with the expansion the cord shows at this point, and with the enormous volume of the nerves lying beside it. . 2. The Cranial Cavity. (Figs. 22, 23, 175.) This is a very irregular oval box, whose walls are formed by the toute parietal, occipital, ethmoidal, and temporal bones. Tt presents for consideration four planes and two extremities. The superior plane offers on the middle line, and towards its superior third, the parietal protuberance, the two lateral crests of which concur _ with that eminence in dividing the cranial cavity into two compartments: — one posterior, destined to contain the cerebellum; the other anterior, incomparably larger, lodging the cerebral hemispheres, and divided by the single rudimentary crest which begins at the falciform eminence, and joins the crista galli, into two lateral sections—one for each hemisphere. Here- after we will see that the folds of the dura mater are attached to this * parietal. protuberance, and to the ridges detached from it, thus rendering much more perfect the partitioning of the cranial cavity, On the lateral planes there is also noticed the division into a cerebellar and cerebral compartment, due to the lateral crests of the falciform process, which are prolonged obliquely to near the sphenoid bone: the first section is formed by the occipital and the inner face of the petrous bone; the — second by the squamous portion of the temporal, the frontal, and the great ala of the sphenoid bone. Both are concave, and marked by digital impressions, as they also are on the superior plane. The inferior plane, very irregular, offers from behind forward: 1, On ‘the median line, the basilar channel, into which the greater portion of the encephalic isthmus is received ; the pituitary fossa, made deeper by a circular fold of the dura mater, and lodging the gland of that name; the optic fossa, where the chiasma of the optic nerves is situated; 2, On the sides, the foramen lacerum, partly closed by cartilaginous substance, and b: the dura mater; the cavernous sinuses and maxillary fissures, outside whic is remarked a deep and wide digital impression for the reception of the mastoid lobule, or inferior lobe of the brain, The posterior extremity of the cranial cavity presents the occipital foramen, by means of which this cavity communicates with the spinal canal. The anterior extremity offers, in the median plane, the crista galli process, or superior border of the perpendicular plate of the ethmoid bone ; on the sides, the two ethmoidal fosse—deep depressions containi the olfactory lobes, and at the bottom of which is observed the cribriform aspect of the transverse plate of that bone. THE ENVELOPES OF THE CEREBRO-SPINAL AXIS, The three membranes which cover the cerebro-spinal axis, and separate — it from the walls of the bony cavity inclosing it, are thus designated, — Generally termed meninges, and distinguished as external, mi and internal meninge, these membranes are better known as the dura mater, — arachnoid, and pia mater—names which will be employed in our description. — The dura mater, or external meninge, is a strong fibrous membrane in contact with the walls of the cranium and the spinal canal. The arachnoid, or middle meninge, is a tunic of a serous nature, which THE CEREBRO-SPINAL AXIS. 661 pairs itself into two layers: an external, applied to the inner face of the ura mater; and an internal, spread, through the medium of the pia mater, ever the cerebro-spinal axis, from which it is again separated in a great number of points by a particular fluid, the subarachnoid. The pia mater, or internal meninge, is the proper envelope of the central ___ nervous stalk ; it is cellulo-vascular, closely adherent to the external surface _ of the cord, united to the visceral layer of the arachnoid by more or less _ dense connective tissue, between the meshes of which is deposited the _ subarachnoid fluid. _ This arrangement of the cerebro-spinal envelopes permits the cerebro- _ spinal axis to be assimilated, to a certain extent, to a viscus, and the bony ‘sheath containing them to a splanchnic cavity, whose serous membrane, the _ arachnoid, is covered outside its parietal layer by a fibrous expansion, the dura mater, and within its visceral layer by a cellulo-vascular tunic, the pia mater, or internal meninge. __ This collective view of the envelopes belonging to the nervous centres will now be followed by a special description of each, in which their spinal and cranial portions will be successively considered, after glancing at them in a general manner. : 1. The Dura Mater. This membrane is the most external and the strongest of the cerebro + envelopes, and covers the walls of the cerebro-spinal cavity, whose form it exactly repeats. It is, therefore, a second protective sheath, which is dilated at its anterior extremity into an ovoid cavity that lodges the _ encephalon, and terminates in a prolonged point in the coccygeal vertebre. It offers two faces: an external, in contact with the walls of the bony ease; and an internal, adhering in the most intimate manner to the external layer of the arachnoid. In several points of its extent it is traversed by the nerves which escape from the cerebro-spinal axis, and by the vessels destined to this portion of the nervous system. Srructrure.—The dura mater possesses the texture of all white fibrous membranes. It is composed of parallel longitudinal fasciculi of connective tissue, mixed with some fine elastic fibres. Bourgelat thought they formed two distinct layers—an external and internal; but nowhere is it possible to demonstrate this. It receives blood-vessels ; the arteries are derived, for the spinal portion, from the vertebral, the intercostals, lumbar, and lateral sacrals; for the cranial portion, meningeal ramuscules, such as the ethmoidal branch of the nasal, the spheno-spinous, and tympanic, mastoideal, and cerebro-spinal arteries. Nerves have been seen passing to its cranial portion ; these have been divided into anterior, middle, and posterior. The. first are furnished by the ethmoidal filament of the nasal nerve; the second from _ the Gasserian ganglion; and the third, by the ophthalmic branch of Willis. The existence of lymphatic vessels has not yet beeu demonstrated. Spmat Dura Marer (Tueca Verresrauis),—This is a very elongated sheath, continuous at the occipital foramen with the encephalic dura mater, and terminated behind by an attenuated point lodged in the narrow channel which, in the middle coccygeal vertebra, represents a trace of the spinal canal, As it is in shape exactly like the latter, its largest diameter is at the atlas, and at the brachial and lumbo-sacral enlargements of the spinal cord. Its capacity depends greatly on the volume of the latter, and in some of its parts it can allow the accumulation of the cerebro-spinal fluid; this 662 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. accumulation is impossible for nearly the whole extent of the cranial region. a The external face of the dura mater is very slightly rae: Preston above, to the walls of the spinal canal; and it is even separated m them, at the intervertebral spaces, by a certain quantity of adipose tissue owed is never absent, though the animals be ever so emaciated. This face co inferiorly, the common superior ligament, and the veins we have descri as spinal sinuses. The internal face gives attachment, between each pair of nerves, to tie festoons of the dentated membrane, a dependency of the pia mater. It is rendered smooth and polished by the external layer of the arachnoid, to which it is so firmly united, that it is needless to attempt their separation. Here the external layer of the arachnoid is réduced to a simple Inyer formed by a row of cells with flattened nuclei. On each side, the substance of this meninge is completely traversed by a double series of orifices for the passage of the spinal nerves, around which it sends small special sheaths as far as the intervertebral foramina. =~ Crantat on Encernatic Dura Marer.—This membrane forms & sac which is exactly moulded by its external face to the cranial parietes, and by its internal face to the superficial surface of the encephalon, The latter, therefore, completely fills the cavity of the cranium, a circumstance that explains why an accumulation of fluid is impossible in this region, External surface.—It adheres strongly, by céllulo-vascular bands, to the cranial walls, whose undulations it follows; this adhesion is not, however, equally marked everywhere, for on the sides of the roof ‘of the cerebral compartment it is least intimate, and it is closest on the middle plane of this roof, on the crista galli, around the parietal protuberance, on its crests, and towards the lateral faces of the cerebellar compartment at the petrous, bones, where the membrane is very thin. This face gives rise to a number of prolonged sheaths, corresponding to the nerves leaving the base of the cranium. - The principal are found around the ethmoidal filaments, the optic nerves, and the two thick branches furnished by the Gasserian ganglion. ) Internal surface-—The internal surface of the cranial dura mater is covered by the parietal layer of the arachnoid, which is firmly attached to it only in the spinal region. It sends into the cranial cavity three pro- longations, which are distinguished as the Salx cerebri (fale, a sickle), tentorium cerebelli (tentorium, a tent), and the pituitary fold. ‘These processes complete the partitioning of the cranial cavity, isolate the various external bulgings of the encephalic mass, and protect them from the compression they might exercise on each other. a. The falx cerebri is a vertical lamina coinrprined between the two cerebral hemispheres, and owes its name to its sickle-like form. Its antero-superior border is adherent and very convex, and corresponds to the crista galli process, as well as to the median ridge on the inner face of the frontal and parietal. bones. This border is very thick, and hollowed internally by a prismatic and triangular venous canal, which con stitutes the median sinus. Towards its inferior border, whith i is free and concave, and corresponds to the corpus callosum, the falciform process is extremely thin, and eribbled like lace-work. The posterior extremity, or base of the falx, rests on the parietal protuberance. a — THE CEREBRO-SPINAL.AXIS.. : 663 ‘The anterior extremity advances in a curve to nesr the optic fossa. In aged animals, there are sometimes found on the faces of the falx cerebri, especially towards its posterior extremity, small yellow granules, known as the Pacchionian glands. They are little nuclei of connective tissue that arise from the subarachnoideal tissue ; meningeal granulations would be a better designation for them than that of glands, b. The tentorium cerebelli is composed of two lateral laminew, which form a transverse partition between the cerebellum and the posterior extremities of the cerebral lobes. Each lamina, coursed internally by one of the transverse sinuses, offers : an adherent convex border, attached to the parieto-temporal crest; a free concave border, turned inwards and a little forwards, remarkable for its thickness and solidity; and, with the second lamina, circumscribing an oval opening through which the encephalic isthmus passes ; a superior extremity, attached to the parietal protuberance; an inferior extremity, which disappears above the Gasserian-ganglion, near the fold that surrounds the pituitary gland. of eee f - Of the two faces of these laminw, the anterior corresponds to the cerebral lobes, the posterior to the cerebellum. ce. The suprasphenoidal, or pituitary fold, is a thick, slightly salient, and almost circular pad, channeled internally by the cavernous sinus, and cireumseribing the sella turcica by enveloping the pituitary gland laterally and posteriorly. oe 2. The Arachnoid Membrane. The arachnoid presents the same disposition as all the splanchnic serous membranes, in being resolved into two layers—a parietal and a visceral, both constituting a perfectly closed sac, outside which the cerebro-spinal axis is contained. The cavity of this sac is traversed by the roots of nerves, the vessels of the brain and cord, and filaments and cellular lamella which pass from the pia mater to the dura mater; around all these its layers form sheaths by becoming continuous with one another. Each of these layers exhibits an adherent and a free face. The adherent: face of the parictal layer is united, as we have already seen, to the dura mater. That of the visceral layer covers the nervous axis in spreading itself over the pia mater, but without accompanying it into the anfractuosi- ties of the central mass ; it is beneath this face of the visceral layer that the cerebro-spinal (or subarachnoid) fluid is confined in spaces which will be studied hereafter. By their free face, which is smooth and moist, like that of all serous membranes, the arachnoid layers are in contact with each Srrvucrure.—The structure of this membrane resembles that of all others of the same nature. ‘Ihe meshes of elastic fibres are most abundant in the cranial portion. Everywhere the parietal layer is only composed of a simple layer of epithelium, The arachnoid. has no proper vessels or nerves; those which pass through it only accompany each other. Srivat Aracunom Memprane.—The po layer presents nothing of interest. The visceral layer is separated from the spinal cord, throughout its extent, by 2 somewhat considerable space (the subarachnoid), in which the subarachnoid fluid is collected; this space is greatest posteriorly, around the terminal extremity of the cord and the nerves of the cauda nina. - The adherent face of this membrane is only connected with the external is 664 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. at = surface of the spinal cord by thin cellular filaments detached from the pia CrantaL or Enorrnaric Aracunomw.—There is nothing special to note in the parietal layer. a If the visceral layer be traced from the occipital foramen, where it is continuous with the spinal arachnoid, to the anterior extremity of the cerebral lobes, it is seen to be prolonged inferiorly on the lower face of the isthmus, as far as the pituitary stalk, to which it furnishes a sheath: the pituitary gland itself is not covered by the arachnoid, except on a portion of the superior or deep face ; from the isthmus it is carried forward, and a on each side of the cerebellum and cerebral lobes. Superiorly, this internal __ layer spreads over the surface of the cerebellum, and is reflected at the bottom of the fissure between that organ and the cerebral hemispheres, over the posterior extremity of the latter, enveloping them separately by descending into the interlobular fissure as far as the corpus callosum. Reaching the anterior extremity of the cerebrum, it gains the olfactory lobes, is principally prolonged on their supero-posterior face, and doubles around the ganglion of grey substance on their inferior face, to be con- tinued with the parietal layer. ari In covering the external surface of the encephalon, the cranial arachnoid does not adhere everywhere to the nervous substance, but is only slightly connected with it, through the medium of the pia mater, at such salient portions as the summits of the cerebral convolutions. Neither does it dip down to enter the sulci existing between these parts, but passes over them, and in this way forms a large number of subarachnoid spaces analogous to that developed over the whole extent of the spinal cord. , ait P These spaces, which are filled by the subarachnoid fluid, differ widely in form and dimensions. In Man, three principal have been described, and these are also found in animals; Magendie has named them the confluentsof — the subarachnoid fluid. Of these three confluents, the anterior is situated in ~ advance of the chiasma of the optic nerves, between the two cerebral lobes ; the inferior, the largest, is comprised between the pituitary stalk and the annular protuberance to the surface of the pedunculi of the cerebrum ; while the third, or posterior confluent, lies behind the cerebellum, at the calamus scriptorius. 2 None of these spaces communicate with the internal cavities of the en- — cephalon, and, consequently, the subarachnoid fluid cannot enter fhem. Magendie has nevertheless described a communication between the pos- terior confluent and the ventricle of the cerebellum ; though the opening he _ described towards the calamus scriptorivs has not been found in the Horse by M. Renault, and we believe we may affirm, with M. Lavocat, that it does — not exist in the other animals. Tue Susaracunoi Fium.—tThe fluid contained in the subarachnoid spaces is slightly yellow or colourless, and perfectly limpid and trans Some authorities admit that it is secreted by the visceral layer of the arachnoid, and others by the pia mater. According to the remark made by — Cruveilhier, the nervous centres are immersed in it, like a footus in the — liquor amnii; and this remark, which is particularly applicable to the — spinal cord, gives the key to the use of this fluid, which keeps the organ _ away from the walls of the spinal canal, deprives it of the greater part of — its weight (Foltz), and thus diminishes every kind of concussion to which it might be exposed. a (This fluid, so necessary for the support and protection of the cord and — THE CEREBRO-SPINAL AXIS. 665 gona alkaline, and contains but a small quantity of albumen ; it varies quantity according to the relative size of the cerebro-spinal axis and its containing cavity, or with the amount of blood sent to this region. By under all circumstances, an equable pressure on the brain and - spinal cord, and the nerves emanating from these, its importance as a hydro- static agent is greatly enhanced.) 8. The Pia Mater. _ The pia mater, the proper envelope of the cerebro-spinal axis, is a thin membrane whose framework, essentially connective, sustains on its external face a very abundant network of blood-vessels and nerves. r immediately to the surface of the encephalon and spinal cord, it d ~ adheres firmly to that surface and follows all its inequalities, penetrating mediate sulcus two layers that lie against each other. The external face of the pia mater, bathed in part of its extent by the subarachnoid fluid, adheres to the visceral layer of the arachnoid by means of a more or less dense and close filamentous connective tissue. From it arise the cellular coverings that constitute the neurilemma of the nerves. Tt detaches a multitude of filamentous or lamellar prolongations to the internal face of the dura mater, which traverse the arachnoid cavity in the Same manner as the nerves and vessels, by being enveloped, like these, in a _ sheath furnished by the arachnoid membrane. Always very short, these eq pe penton simulate the adhesions established between the two layers of a membrane. The internal face is united to as nervous substance by multitudes of _ arterial and venous radicles or connective filaments, which leave the pia mater to plunge into this substance. _ The vessels of the pia mater form a very close network, from which are _ detached branches that reach the medulla and encephalon. They are ac- companied by nervous filaments, and surrounded by perivascular canals, which _ are now believed to be lymphatics. Certainly, in their interior a colour- less fluid cireulates, and which contains globules very like those of lymph. Spmat Pra Marer.—Less vascular than the cranial pia mater, with which it is continuous towards the medulla oblongata, this membrane is remarkable for the arrangement of the prolongations that arise from its two faces. _ _The internal prolongations form longitudinal lamin at the fissures of the cord, and enter these fissures. The external prolongations attach, as we have said, the pia mater to the _ external meninge. A very large number are filamentous ‘in form, and are dispersed over the superior and inferior surfaces of the cord. Others consti- tute, on each side of the organ, a festooned band named the dentated ligament gamentum dentata, or denticulatum). These ligaments exist throughout the ‘ire > length of the medullary axis, between the superior and inferior nerve- roots: their inner border is confounded for its whole length with the pia “mater ; and their outer margin, cut into festoons, attaches itself to the dura mater by the summit of the angles separating these festoons. To complete this description of vale to ak: Bie there may be noticed &@ posterior or coccygeal prolongation (jfilum terminale): a very narrow process _ formed by this staan eats we the stares extremity of the cord, situated in the midst of the cauda equina nerves, and attached to the bottom of the conical cul-de-sac at the termination of the dura mater. between the cerebral or cerebellar convolutions, and forming in each inter- - 666 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. — (This ligament, or membrana dentata, serves to maintain the position the spinal cord in its hydrostatic bed, and to prevent the nerves proce from it being dragged during flexion of the spine. ) . Crantan, on Enoxrnatic Pra Marer.—The vascular clement] dominates in this portion of the internal meninge. ‘This membrane sends scarcely any prolongations to the dura x except at the medulla oblongata, though it projects remarkably aso into the cerebral mass and the sides of the cerebellum. _The descriptior the velum interpositum, and the cerebral and cerebellar plecus choroides, belo: to the encephalon. (The pia mater is extremely vascular on the surface of the cease forms remarkable anastomosing loops in the intermediate spaces of tl convolutions, which chiefly supply the grey substance. It is the nut membrane of the brain and spinal cord. Its nerves accompany its ar branches, and are minute filaments from the sympathetic.) + DIFFERENTIAL CHARACTERS IN THE ENVELOPING AND PROTECTIVE PARTS OF THE CER SPINAL AXIS IN OTHER THAN SOLIPED ANIMALS, The bony ‘canal that protects the spinal cord and brain does not present a worthy differences in the domesticated animals, and the subject has been sufficiently studied in the osteology of the head and vertebral column, - With regard to the meninges, their number and general disposition are the same i all the species. COMPARISON OF THE ENVELOPING AND PROTECTIVE PARTS OF THE CEREBRO-SPINAL — AXIS OF MAN WITH THOSE OF ANIMALS, ¢ There is nothing particular to be said respecting the cranial cavity al spinal can cana nor yet the arachnoid and pia mater. The dura mater offers the folds Solipeds, and, in addition, a falx cerebellum, that extends from the tentorium of —— name to near the foramen magnum. The meningeal granulations, or Pacchionian g are nearly constant in aged ‘individuals, and their volume is sometimes so conside that by compression they thin away, and even perforate, the cranium at correspc pola Pl CHAPTER II. THE SPINAL CORD. Preparation. —Isolate the cranium and vertebral column from all the other paris of body; open the spinal canal and the cranial cavity by their superior surface, as figure 316, by.raising with a chisel (or rogne-pied, the farrier’s “ toe-knife ? and ham the roof of the skull and annular portion of all the vertebre. The or, may then studied in situ in its bony case, and surrounded by its membranes; a ext the whole cerebro-spinal axis inclosed in the dura mater, and open up the latter ¢ the course of the cord, so as to completely expose that rtion of the nervous system, (The saw and farrier’s pincers, or spine ratchet, will be found useful auxiliaries i tedious and delicate operation of exposing the brain and cord; and pertioulars @ f ing open the cranial cavity. An easy mode of obtaining access to the spinal ea its contents, is to saw through the amine of the vertebra on each side, at the re the transverse processes, an« raise the arches with the chisel or toe-knife.) EXTERNAL CONFORMATION OF THE SPINAL CORD. General view.—The spinal cord is that portion of the nervous centres v occupies the spinal canal. It is a thick, white,and irregularly cyline cord, commencing at the occipital foramen, where it continues the medull oblongata, terminating ina point at the upper third of the sacral canal, o1 *; "sodoje Ato oy ysnoryy Sarssud sqoor teddy ‘a ‘a fared jwuondeoxa uv uo uoySaed aSuig ‘a {syo0r soradns oy. go uySuud oydyyyngy {0 { sy00x ro1szeyny “a { syo01 tonedng *y n I Y Jo Vly [A [04 Maju] ! s ~ = ‘SHAUAN ‘IVNIdS AHL 40 SLOOU AHL GNV GOVA UddA SLI ONIMOHS ‘SAXUTd ‘IVIHOVUd UO “ATOM TVOIAUAO AHI LV GUOO TYNIds AHL 40 LNGIKDAS m fp is 4 , j : mh _/7) | 7 | AA\\\Ss Al ile a THE SPINAL CORD. LLAEER BAUER TFL, 668 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. little beyond that, and giving rise at cach side, during its course, to the superior and inferior roots of the spinal nerves. Weight.—-In medium-sized animals the weight of the cord is represente by the following approximate numbers : for the Horse, 104 ounces; the . ; 5+ ounces; Cow, 7} ounces; Sheep and Goat, 1} ounce; Pig, 2h onan Dog, 14 ounces; Cat, 45 drams. Fad Figure and volume.—The medullary cord is slightly depressed above and “ below, throughout its whole length; in whatever part we examine transverse section of it, we will always find the lateral diameter greater them the vertical, and that this section appears regularly elliptical. ; __ Its volume is far from being uniform. In following it from before to behind, we at first remark that it presents the same dimensions to the ie cervical vertebra, and that between this point and the second dorsal vertebra it forms an oblong enlargement, designated the brachial (brachio-rachidian ) bulb or enlargement. Beyond this, it assumes its primitive volume, and becomes — gradually smaller even than in the cervical region. Towards the middle of the loins, it again augments to constitute the crural (lumbo-rachidian) bulb — x or enlargement, which extends to the entrance of the sacral canal. After this dilatation comes a conical prolongation, whose point represents the terminal extremity of the cord. If we compare the diameter of this medullary axis with that of the spinal canal, we will observe, as has been already said, that the capacity of the — containing cavity is generally related to the volume of its contents, and that the former is, as a rule, most capacious at the cervical and lumbar enlarge- ments. It will even be noticed that the dilatation the spinal canal offers at_ these two points, is relatively more considerable than the excess in volume of — the cord. This is because the mobility of the spine, which is justly very — great in these two regions, requires this difference to secure the spinal axis — from contusions during the movements executed by the vertebral column. This protective combination is also found elsewhere: at the atlas, for example, where we know the motion is considerable; and in the entire extent of the cervical region, which in this respect greatly exceeds the dorsal region. } External surface of the cord.—Covered by the pia mater, this surface presents an extremely simple disposition. On its superior and inferior — planes, at each side, we remark the double series of sensitive and motor roots of the spinal nerves, which are implanted in the same longitudinal line to right and left of the median plane, and are collected in fascieuli- opposite the intervertebral foramina. In the middle line, and throughout the entire length of the organ, there are two deep and narrow fissures: one superior ( fissura longitudinalis— superior), the other inferior (fissura, longitudinalis inferior), into which the pia mater enters. Four other fissures have been described at the point ¢ af emergence of the nerve roots, under the names of superior and eye collateral fissures (or sulci); but the two superior alone exist, and eyen these are often scarcely noticeable. ‘ ‘2 ~~ INTERNAL CONFORMATION AND STRUCTURE OF THE SPINAL CORD, * In making a transverse section of any portion of the cord, we m ay - convince ourselves that it has an internal cavity. This contead canal i elliptical, and lined by, cylindrical ciliated epithelium, resting on @ hit n connective membrane, the ependymis of Virchow. This scction also shows THE SPINAL CORD. 669 the two median fissures mentioned in describing the exterior of the cord, the inferior of which is wider and deeper than that of the superior, whose situation is scarcely perceptible. 80 as to completely divide the cord into two lateral halves, but remain separated by two thin horizontal and superposed bands _ of nervous matter, that pass from one end to the other of the me- dullary axis. The inferior, formed _ of white substance, corresponds to the bottom of the inferior fissure ; while the superior, composed of ee meter, meets the superior These bands are named the white and grey commissures of the spinal cord (Fig. 318). Notwithstanding the presence of these two commissures between _ the lateral halves of the spinal axis, these latter do not the less con- _ stitute two symmetrical systems, whose structure will now be _ studied. Each medullary cord repre- _ These two fissures advance one before the other, and do not meet Fig. 318, SECTION OF THE SPINAL CORD OF THE HORSE AT THE LUMBAR REGION; MAGNIFIED TWO DIAMETERS. 1, Superior median fissure; 2, Inferior median fisStre; 3, 3, Superior collateral fissures ; 4, 4, Inferior ditto; 5, Grey commissure; 6, White commissure; 7, 7, Superior grey cor- nua; 8, 8, Inferior grey cornua; 9, Central canal, _ sents a semi-cylinder of white sub- stance, in the centre of which is - @ mass of matter, that varies somewhat in quantity in different regions, _ but the arrangement of whichis everywhere the same. Thus, inwardly, this grey matter joins the grey commissure ; above, it sends off a thin prolongation which traverses the thickness of the medullary cord (superior grey cornu), to reach the bottom of the superior collateral fissure; below, it gives rise to an analogous, though a thicker and a more irregular, prolongation one ea grey cornu), which is directed well in front of the inferior roots, t does not reach the surface of the cord. In consequence of this arrange- ment, the grey substance of the medulla forms altogether a kind of capital H, whose horizontal branch is perforated in the middle by the central canal. 3 This disposition of the grey substance causes the white matter to be divided, in each lateral moiety of the spinal axis, into three cords or B columns ; the superior of these is perfectly isolated, and is com- ‘prised between the middle superior fissure and the origin of the sensitive roots; another, the inferior, united to that of the opposite side by the white ‘commissure, is limited, inwardly, by the inferior median fissure, and out- wardly by the line of origin of the motor nerve-roots; while a third, the . or intermediate, thicker than the others, is confounded superficially with the inferior, and formed by all that portion of the medulla situated between the lines of origin of the superior and inferior roots. Of these _ three columns of the medullary axis, the first is sensitive; the other two, _ which in reality are only one, are motor. Srrvcrure.—Independently of the epithelium mentioned when describing 670 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. the ependymis, connective tissue, nerve tubes, nerve cells, and vessels on ' into the structure of the medulla. ; i The connective tissue of the spinal cord is very delicate, rich in nuclei, _belongs to the variety that histologists have named “‘ reticular ” or“ ¢ It appears to arise from the pia mater, and forms lamelle that pe the nerve-suhstance to meet and anastomose with each other, and f become confounded with the ependymis around the central canal. — tissue, which is also named neuroglia, has been compared to a spo whose spaces are deposited the other elements of the cord, This ne exists in the white and grey substances, but is more abundant in the su than in the inferior grey cornua. It surrounds the upper extremity of th former in becoming softer and more transparent, and is here desi Z gelatinous substance of Rolando (substantia gelatinosa). It constitutes, great part, the grey commissure, and can be deeply stained by the carminate of ammonia. a Fig. 319. TRANSVERSE SECTION OF SPINAL CORD OF MAN THROUGH THE MIDDLE OF THE LUMBAR REGION, SHOWING ON THE RIGHT SIDE THE COURSE, OF THE NERVE- ROOTS, AND ON THE LEFT THE POSITION OF THE PRINCIPAL TRACTS OF VESICULAR | MATTER. ,y : a A, A, Anterior or inferior columns; P, P, Posterior or superior columns; L, L, Lateral columns.—a, Anterior or inferior median fissure ; p, Posterior or superior median fissure ; 6, b, 6, b, Anterior or inferior roots of spinal nerves; c, c, Posterior or superior roots; d, d, Tracts of vesicular matter in anterior column; ¢, Tracts of — vesicular matter in posterior column ; f, Central canal; g, Substantia gelatino a, " The tubes and cells form, with the neuroglia, the whole of the substance. The cells have at least five prolongations, and the tub reduced either to the axis-cylinder (awis-fibre), or to this and a ver layer of medullary substance. The cells are not uniformly distributed in the grey substance, but : arranged in small masses that constitute three longitudinal columns: t THE SPINAL CORD. 671 F = in the inferior, and one in the superior grey cornu. The columns cor- to what Stilling has named the nuclei of the nerves, A fourth of cells, the superior vesicular column Clarke, or dorsal nucleus of Stilling, is Fig. 820. at the point where the grey com- -missure joins the cornua. The nerve-tubes _ (or tubules) affect longitudinal, transversal, . aehges, and vertical directions. ie. ey bring the cells of one lateral moiety of the medulla into communication with: 1, The tubes of the white substance ; 2, Each other; 3, The cells of the opposite moiety, by passing into the commissures ; 4, The tubes of the white substance of the op- posite moiety, by following the same course. The neuroglia and nerve-tubes consti- tute the white substance, which is decom- as we know, into three cords. All the tubes of this substance do not ascend to the brain, as was believed for a long time ; _ the opinion that the tubes of the spinal _ nerves formed the medulla and extended to the brain, has been abandoned since Volk- mann measured, comparatively, the section of all these nerves and that of the nervous -axis. ____ (Volkmann has established the fact, that the size of the medulla corresponds with the _ number of nerve-tubes given off at any point. He gives the weight of four segments, each 2,8; inches in length, from the spinal cord of the Horse, and the relative extent of the matter in square lines; these are as ollows : . ; | ' Area Area Grains. of Grey of White Matter. Matter. From below 2nd Spinal Nerve, 219 13 109 ” ” Sth = » 23 28 142 * » 0th . » 163 il “9 “ae ~ «ol 25 121) In the white-substance the tubes are lon- . . . LONGITUDINAL SECTION THROUGH gitudinal, oblique, or transversal ; the latter ~~ cervicALENLARGEMENT OF SPINAL arise from the cells of the grey substance, corp or car. and represent the roots of the nerves ac, kage white columns; ac’, Por- ing either by the superior or inferior tien showing the arrangement of tine, ; y - the longitudinal fibres; 16, Pos- S z terior white columns; «G, Gre The tubes of the anterior cords pass to substance between them(the vasiclie being omitted to avoid obscuring the course of the fibres); A, Anterior roots of the nerves; P, Posterior roots, consisting of three kinds: the first, a, crossing the posterior columns horizontally, and then pass- ing obliquely downwards, across tle grey substance, into the anterior columns; the second, b, traversing the posterior columns horizontally, and then losing themselves in the grey substance; the third, c, for the most part becoming continuous with the longitudinal fibres of the posterior column ; all, or nearly all, ultimately entering the grey substance. 672 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. the cells of the grey substance, or reach the encephalon by remaining in tl corresponding moiety of the medulla; for instance, the fibres of the ri half of the medulla gain the brain ‘without passing into the left hal if Those of the lateral cords decussate, each cord sending to, and receiving ft from, the other, tubes which cross in the white commissures. ‘The posterior cords contain fibres that extend directly to the brain: these are sensorial’; J 3 there are also found transverse fibres that enter the cells of the superior grey cornua, and others that pass into the cells of the inferior or motor cornua, hele Such is, in a few words, the disposition of the nerve-elements in ‘the . medulla. The subject is a very long and complicated one, which cannot be dealt with in a more detailed manner in a work on descriptive anatomy. Vessels—The medulla receives arteries from the ramifications of the — “2 pia mater. The grey is richer in vessels than the white substance; the — latter is penetrated everywhere by a large number of minute arteries ; while “s 3 the first is traversed by the divisions of an artery that is thrown off by the median spinal, and ascends towards the bottom of the inferior fissure. The veins follow the arteries, and constitute two somewhat voluminous vesse that pass along the grey commissure, to the right and left of the cen canal, a rat DIFFERENTIAL CHARACTERS IN THE SPINAL CORD OF OTHER THAN SOLIPED ANIMALS. In all the species, the white and grey substances affect the disposition above de- = scribed; only some slight differences in the reciprocal volume of each have been remarked. As in the Horse, the spinal medulla does not extend beyond the sacral — region; its length has no relation to that of the coecygeal region, as certain ee would, in principle, establish; in the rabbit, for example, the tail of which is sort, the spinal cord is prolonged into the coccygeal vertebra. COMPARISON OF THE SPINAL CORD OF MAN WITH THAT OF ANIMALS. * Z The spinal medalla of the adult Man does not reach beyond the first lumbar vertebra, though in the foetus it is in the coceyx. Jt is rounder than in the Horse, and the grey substance is, relative to the white, more abundant than in the spinal cord of the oe ' ticated animals. The posterior grey cornua are also larger and Jess elongated than 77, superior cornua in the Horse ; and the roots of the nerves are also moré voluminous. _ ce = > a, a CHAPTER III. THE ENCEPHALON. ArticLe 1.—THe EncerHALon As A WHOLE. Tue encephalon is that portion of the nervous system which is lodged in the cranial cavity. It succeeds, without any line of demarcation, the spinal cord, of which it may be considered, with regard to its figure, as a kind of ~y efflorescence, ee General form and constitution —In shape it is an ovoid mass, eloustedle from before to behind, and very slightly depressed from above to below. 4 When it is viewed on its superior face (Fig. 821), we first see, behind, a white pedicle, the prolongation of the spinal cord, and a single lobe of a grey colour designated; the cerebellum. In front of this is remarked two other lobes, separated from the first by a deep transverse fissure, into which Co tulle 2 THE ENCEPHALON. 673 the tentorium of the cerebellum passes. Isolated from one another on the middle line by a shallower fissure, these two lobes constitute the brain, and are usually named the cerebral hemispheres. Tn turning over the encephalon Fig. 821. to examine its inferior face, we see that the posterior peduncle of the - organ—a continuation of the spinal _ cord—is prolonged beneath the ce- rebellum, which is joined to the | lateral parts of its superior face ; this portion then enters the cere- bral hemispheres by their inferior face, behind two thick white cords— the optic nerves, which mark the anterior limit of this prolongation (Fig. 322). This is the isthmus of the encephalon: % name given to it because it actually forms an inter- mediate bond between the three enlargements which form the prin- cipal mass of the encephalon. The cranial portion of the cen- tral nervous mass is, then, com- pesed of three apparatus: the isthmus of the encephalon, a pro- longation of the spinal cord; and the cerebellum and cerebrum, bulbous lobes grafted on the superior face and anterior extremity of this pe- duncle. These three divisions ure very well seen in their entirety and reciprocal relations in Figure 329. We will study them sepa- C ra ney = in CRD re GENERAL VIEW OF THE BRAIN; UPPER SURFACE, olume of the encephalon.—Con- xr aunts oblongata; 2, Middle lobe Of the trary to what = found in the spinal cerebellum; 3, 5, Lateral lobes of ditto; 4, 4 cord, the dimensions of the en- Cerebral hemispheres; 5, Interlobular fissure; cephalon closely represent those 6, 6, Ethmoidal lobules, of the cavity containing them: the visceral layer of the arachnoid lying everywhere immediately on the proper envelope of the nervous mass, the pia mater, except at the subarachnoid spaces ; and, on the other hand, the arachnoid cavity can scarcely be said to exist while the dura mater is, as it were, glued to the cranial walls, and in reality constitutes their internal periosteum. The encephalon has, therefore, no room to move in its receptacle, but is maintained in it in an almost absolutely immovable condition, which coincides exactly with that of the sutures or cranial articulations. Weight.—The total weight of the encephalon, in average-sized animals, may be inferred from the following figures : Horse, 22 oz. 15 drams;.Ass, 12 oz. 11 drams; Ox, 16 oz. 15 drams; Sheep and Goat, 4 oz. 94 drems; Pig, 5 oz. 10 drams: Dog, 6 0z, 54 drams; Cat, 1 oz. 1 dram. In comparing these figures with those of the spinal cord, it will be seen that the relative weight of the medullary axis to that of the encephalic mass 2x 674 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. differs notably in the several animals, being highest in the Dog. relations in each species, between the two divisions, are the following : 1: 5,14; Cat, 1: 3,75; Sheep and Goat, 1: 2,60; Ass 1: 2,40; Pig, I im 2,30; Horse 1: 2,27 ; Ox, 1: 2,18. We give these numbers, as it has always been attempted to establish in the predominance of the en ; the cause of the development of intelligence, and that the best measure of this predominance is really the relation of the spinal axis to the encephalic mass. It has also been attempted to measure this predominance of the encephalon Ae comparing its weight with that of the entire body; but it is sufficient to cast one’s eye over the tables drawn up with this view in several anatomical and — physiological works, to be convinced that this basis does not possess all os value desirable, nye Preparation of the encephalon.—To study the encephalon, it is necessary to extach from its bony receptacle ; a result achieved in two ways. The first consists in er the roof of tie cranium by hammer and chisel, after removing from its exterior all the parts covering it, or which are in its vicinity. The dura mater is then exdianll ‘with scissors, and the "encephalon, which is thus directly reached, is comple isolated by — raising its posterior extremity, and cutting from behind to before all the nerves through the foramina atthe base of the cranium, with the pituitary stalk, as we as the extremity of the olfactory lobes, This method is very expeditious, but it sacrifices the pituitary gland, which remains firmly incrusted in the se a turcica: an inconvenience — we obviate by resorting to the second procedure. In this, the cranium is opened by its base or floor, after separating the head from the trunk, cutting away the lower ree ee tongue, and os hyoides, and excising all the soft parts so as to expose the bony surfaces. The head, thus prepared, is held by an assistant, the roof of the cranium resting on a table or block. Armed with a chisel ‘and hammer, the operator first removes the — zygomatic arches and styloid processes of the occipitel bone, then the condyles of this bone, the basilar processes, and the sphenoid, palate, aud ethmoid bones, returning to the lateral portions of the cranium, which are chiselled away in succession from the cocrpien al the ethmoid bones. The encephalon being sufficiently exposed, is relieved from its dura ~ mater as in the first method, and raised in the left hand to destroy, by means of ee held in the right hand, the attachments which yet fix it to the cranial roof, and which — are chiefly the veins that open into the sinuses of the dura mater. In afterwards ex- cavating the ethmoidal fosse with the point of a scalpel, the olfactory lobes are para and the nervous mass is free. This procedure is more difficult than the several advantages over it; for not only do we preserve the pituitary at { es the ethmoidal lobes more intact, and may also have, if desired, the ganglia of the — cranial nerves, with a more or less considerable portion of the nerves themselves. After indicating the methods for extracting the encephalon from its bony case, we ought to say some words as to the course to be pursued in order to study it successfully. oe To do this it is advantageous to have two brains; one of these should be hardened steeping it for some weeks in alcohol (or methylated spirit), or in water to which has been added a tenth part of nitric acid. ‘This hardening contracts the nervous su and causes tle cavities and reliefs to appear more manifest, (It is a good plan to place "I the brain, base uppermost, in a yen vessel, and if a piece of cloth be spread beneath it, its removal therefrom will be great vA facilitated.) é We commence by examining rapidly the nee apparatus, and pass immediatel. tos the study of the isthmus, of which it is necessary to have at first a well-defined i We therefore take a hardened specimen, and isolate this portion of the encephalon in” the manner represented in figure 323 ; to do this, it sutfices to cut through the pedar cles — of the cerebellum, and excise the cerebral hemispheres upwards and backwards; the — remains of these and the cerebellum should be preserved for an analysis of their — structure. The isthmus thus isolated is fitted for an examination of its external contre; mation and its internal cavities: the ventricle of the optic layers and the aqueduct of Sylvius, into which we may penetrate by a superior longitudinal incision, ) After the isthmus, the cerebellum is to be studied : in its external conformation, on an intact specimen ; and in its internal conformation and structure on the incised piece. We terminate with the cerebrum, whose superficies is soon examined, and whose interior should be studied in the following manner :—It is necessary to begin by demon- strating the existence of ventricles in the olfactory lobes, and their communication — with all the other internal cavities of tle brain, which can easily be done by the in- flation of one of these organs by means of a straw (or dissecting-case tube) which » THE ISTHMUS. 675 raises the pituitary g!and, the cerebral lobes, and the cerebellum. Then we pass to the co callosum, which is exposed, as in figure 330, by a horizontal section of the hemi- res across the centrum ovale. The corpus callosum of each side is afterwards on the median line to reach the interior of the lateral ventricles, and this great com of the brain ought, after studying the septum lucidum, to be cut acrossin the middle and turned over, as in figure 331, so as to show the cerebral trigonal (fornix). The _ foramen of Monro is next examined, then the corpus striatum, hippocampi, tenia semi- ¢ire choroid plexus, and velum interpositum, which are exposed by the ablation of hippocampi and trizonal. Lastly, we return to the foramen ‘of Monro to study its 5 eth at with the ventricle of the optic layers; it will be well, also, to again ex- _ amine the latter, as well as the aqueduct of Sylvius and the ventricle of the cerebellum, we arrive at in dividing the organ through the middle and separating the halves. ____ Two longitudinal and vertical sections, one median (Fig. 327), the other at the side bs Gig. 229), will not be without utility in the study of these particulars. They may be ie: means of a saw, the brain remaining inclosed in the cranial cavity. (A useful implement for removing the bony casing of the brain without risk of it, is a chisel whose thin cutting edge is slightly concave, the corners being smvoth and rounded, and projecting beyond the cutting edge.) Articie I.—Tue Istrumus. We will study in succession the external and internal conformation of this organ, and its structure. EXTERNAL CONFORMATION OF THE ISTHMUS. ___‘The isthmus is a prismatic prolongation of the spinal cord supporting the _ eerebellum, and terminating in the cerebral hemispheres; it increases in size from behind to before, and may be considered as having four faces and The inferior face (Fig. 322), on which we can distinctly, and without any | sola perceive the natural limits of the isthmus, is crossed nearly in middle by a thick fasciculus of arciform fibres, which constitute the _ annular protuberance (protuberantia annularis), pons Varolii, or mesocephalon (or nodus encephali). All the portion lying behind this fasciculus belongs to the rachidian bulbus rachidicus or medulla oblongata). That in front forms the cerebral peduncles (crura cerebri). The superior face (Fig. 323), covered by the cerebellum and the posterior extremity of the cerebral lobes, is more mammillated than the pre- ceding. Passing from behind to before, on the superior face of the medulla there is remarked the section of the peduncles of the cerebellum, the valve of Vieussens, the corpora quadrigemina, and the optic layers (thalami optici). The lateral faces (Fig. 324), concealed in their anterior part by the hemispheres of the brain, exhibit the profile of the medulla oblongata, pons _ Varolii, peduncles of the cerebellum (crura cerebelli), cerebral peduncles __ (erura cerebri), corpora quadrigemina, and thalami optici. “The posterior extremity of the isthmus belongs to the medulla oblongata, and _ ¢ontinues the spinal cord, from which it is only distinguished artificially. _ The anterior extremity is enveloped, below and on each side, by the oblique fasciculi which form the two optic nerves, and beneath which are insinuated the fibres of the isthmus before they pass into that part of the cerebral hemispheres which bears the name of corpora striata, After this enumeration of all the organs whose aggregation constitutes the isthmus of the encephalon, we will examine them in detail, and in the following order: 1, Medulla oblongata ; 2, Pons Varolii ; 3, Crura cerebri ; 4, Crura cerebelli; 5, Valve of Vieussens; 6, Corpora quadrigemina ; 7, Thalami optici, After these, we will describe the pineal _ ituitary x 676 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. . glands: small appended lobes pli ced one on the superior, the other on the — inferior face of the isthmus.’ eae Fig. 322. Medulla Oblongata. (Figs. 823, M 324, 329.) eae The medulla oblongata constitutes the posterior portion of the encephalie isthmus; it succeeds the spinal cord, and extends forward as far asthe pons Varolii. It isa thick peduncle of a white colour, wider before than behind, flattened above and below, and havin four faces—-an inferior, superior, anit two lateral. Inferior face (Fig. .322).—This face rests in the channel of the basilar __ process. Convex from side to side, and limited anteriorly by a transverse fissure which separates it from the pons Varolii, posteriorly it does not offer anything to distinguish it from the medullary axis. - On the middle line there is a well- _ marked fissure, a continuation of the — inferior fissure of the cord, which lies between two very elongated promi- nences that are sometimes but little apparent, and from their form are named the pyramids of the bulb (corpora GENERAL VIEW OF THE BRAIN; Lower PY" amidalia) (Figs. 822, 19; 338, 6). aii ER BEE The base of these pyramids touches ‘1, Olfactory lobe; 2, Cavity of the olfactory the pons Varolii, and their apex 18 lobe; 3, External root of olfactory lobe; insensibly lost, posteriorly, on reach- 4, 5, Cerebral hemispheres ; 6, Cerebellum; ing the spinal cord. : 7 Onis chia, or commissore: 8 Dita” Qutwardly is an almost plane si pred ce ai Oras cerebri; 12, Third face, bordered anteriorly by “3 trans- cranial nerve; 13, Fourth nerve; 14, Pons Verse band which lies immediately — Varolii; 15, Fifth nerve; 16, Sixth nerve; behind the pons Varolii ; sometimes 17, Seventh and eighth nerves; 18, Me- jt ig covered for the greater part of its dulla oblongata, the number being placed extent by a very thin expansion o$3 on the olivary body ; 19, Anterior pyramid ; F : P 20, Roots of ninth, tenth, and eleventh arciform fibres, between the anterior “4 nerves; 21, Twelfth nerve. border of which and the transverse 4 ' There is far from being any agreement as to the number of parts which ought to compose the encephalic isthmus, some authorities making more, some less. The limits — of this small apparatus will, nevertheless, be found perfectly cireumscribed if it be ex- amined in the lower animals, and particularly in the Horse. An antero-posterior section — of the encephalon made to one side of the median plane appears to us all that is needed to definitely settle the point. This section, seen in figure 329, shows in the plainest — manner that the encephalie prolongation of the spinal axis extends to the corpora striata, and that it comprises the caotalia oblongata, pons Varolii, cerebral and cerebell, peduncles (or crura), the corpora quadrigemina, and the thalami optici, All these, the Selong to one and the same system—the medullary peduncle, which serves as a bo of union between the three principal masses of the encephalon, and Which we have designated the isthmus. It may be added that this manner of considering the encephalie _ isthmus perfectly agrees with the teachings of physiology. a THE ISTHMUS. 677 band, and particularly in pieces that have been hardened by alcohol or acidulated water, is seen a slight oblong prominence which corresponds to what in Man is designated the olive! (corpus olivare); it is isolated from the id by a longitudinal groove, whence emerge, in front, the roots of the sixth cranial pair, behind, those of the twelfth; outwardly, it is limited and separated from the restiform body by the origin of the majority of the roots belonging to the glosso-pharyngeal and pneumogastric nerves. Superior face.—Covered by the cerebellum, it is channeled in its middle by an excavation (Fig. 323, 5), which constitutes the floor of the fourth _ yentricle. This cavity is prolonged forward above the pons Varolii, between the cerebellar peduncles, and from its forming behind an angle resembling the — of a pen, it has been named ‘the calamus scriptorius. Lo wo thick cords, prolongations of the superior fasciculi of the medulla inalis, border the calamus scriptorius on each side; these are designated corpora restiformia. Lying together at their posterior extremities, they separate anteriorly, so as to represent the branches of a V (Fig. 323, 1). Lateral faces.—Much narrower than the other two, and showing two thick borders, these faces give the profile of the corpora restiformia (Fig. 324, 2), corpora pyramidalia (4), and the fasciculus between these two. 2. The Pons Varolii. (Figs. 322, 14; 324, 5.) The Varolii, also named the tuber annulare or mesocephalon, is that part of the brain which stands out prominently across the isthmus, between the medulla oblongata and the crura cerebri, and which is lodged in the anterior depression of the basilar process. ._ It is a semicircular band of white transverse fibres thrown across, like a bridge, from one side to the other of the cerebellum. In every sense it is convex, wider in its middle than in its lateral portions, and. crossed from behind to before by a shallow median groove for the basilar artery. On its free surface, whose principal features we have just described, it offers for consideration two borders and two extremities. The posterior border, slightly convex, is separated from the medulla oblongata by a faint groove. The anterior border, also convex, but indented in its middle, largely over- hangs the crura cerebri, which are limited on this side by a well-marked fissure "The extremities are bent upwards to enter the substance of the cerebellum, in the form of two thick cords, which constitute the middle crura cerebelli ig. 324, 6). They exhibit the apparent origin of the trifacial nerves. e pons Varolii does not exist in birds. 8. The Pedunculi or Crura Cerebri. (Figs. 822, 11; 324, 7.) These are two very large white fasciculi, visible at the inferior surface and sides of the isthmus, coyered superiorly by the corpora quadrigemina and thalami optici, and continuous, above the pons Varolii, with the fibres of the medulla oblongata; while their anterior extremities enter the cerebral hemispheres. These peduncles (or crura) are separated from each other by a middle ' This prominence corresponds to the corpus olivare of Man only in its position, for it has not its structure. 678 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. fissure —the interpeduncular, which bifurcates in front to circumscribe the mammillary or pisiform tubercle (corpus albicans, bulbi fornicis) (Fig. 327, 18): a small, single, and rounded elevation of a white colour, like the peduncles, covered by the pituitary gland, whose root is represented by the tuber cinereum, and is situated in front of this body. Behind, the crura cerebri are limited by the anterior border of the pons Varolii. In front, they are circumscribed by the optic nerves, which obliquely around their anterior extremity and join on the middle line before the tuber cinereum, to form a commissure called the chiasma of the optic nerves (Fig. 322,7). On the sides, their tissue is confounded with that of the Fig, 323. SUPERIOR VIEW OF THE ENCEPHALIC ISTHMUS, 1, 1, Corpora restiformia ; 2, Section of the middle cerebellar peduncles ; 3, Section of the posterior cerebellar peduncle; 4, Anterior cerebellar peduncle; 5, Floor of the posterior ventricle ; 6, Valve of Vieussens; 7, 7, Tubercula testes ; 8, 8, Tubercula nates; 9, 9, Thalami optici; 10, Corpus geniculatum internum ; 11, Corpus geniculatum externum ; 12, Corpus striatum ; 13, Tenia semicircularis; 14, Pineal gland; 15, Its peduncle; 16, Common anterior open- ing; 17, 17, Anterior pillars of the trigonal ; 18, Trifacial nerve; 19, Facial nerve; 20, Auditory nerve; 21, Glosso-pharyngeal nerve ; 22, Pneumogastric nerve; 23, Spinal nerve. other two, related by its inner border corpora quadrigemina and thalami optici, which are superposed on the cerebral peduncles. It may be remarked that the part of their lateral face situated below the tubercula testes, forms a well- defined triangular space, designated the band of Reil, lateral triangu Jasciculus, and lateral oblique fasci- culus of the isthmus. 4. The Crura Cerebelli. The cerebellum is attached to the upper face of the isthmus b two short and thick lateral funiewli of white substance, between which is comprised the posterior ventricle; these constitute the cerebellar crura. Three distinct fasciculi enter into the composition of each of these cords: an anterior, a posterior, and a middle. The latter, or middle cerebellar peduncle (crus cerebelli ad pontem), is the largest of the three. It is formed by the prolongation of the extremities of the pons Varolii (Figs. 323, 2; 324, 6). The posterior cerebellar (crus ad medullam oblongatum), the most slender, is formed by the _ restiform body, one portion of which — is reflected below the posterior root of the auditory nerve to reach the substance of mi cerebellum. It is closely united to the preceding, from which it is with difficulty dis- tinguished (Fig. 323, 3). The anterior cerebellar peduncle (processus e cerebello ad testes) isa fasciculus very distinct from the to the middle peduncle, which it — THE ISTHMUS. 679 obliquely crosses, loses itself in the cerebellum by its supero-posterior extremity, arriving behind the testes, and passing beneath these sma]l organs by its antero-inferior extremity, along with the band of Reil or supero-lateral fasciculus of the cerebral peduncles. In studying the structure of the cerebellum, we will see how these peduncles comport themselves in its interior. 5. Valve of Vieussens. (Fig. 323, 6.) This designation is given to a very thin, white lamella which anites, on each side, the two anterior cerebellar peduncles. In shape it is nearly a ogram. Its superior face is covered by the cerebellum ; the inferior concurs in forming the floor of the cerebellar (fourth) ventricle. The two lateral borders are joined to the peduncles this valve unites; the anterior is attached behind the testes; while the posterior adheres to the anterior yermiform eminence (linguetta laminosa) of the cerebellum. Gall has considered this lamella as a commissure of the anterior cere- bellar peduncles, and we think rightly; for we see it formed almost exclusively of transverse fibres which run from one of these peduncles to the other. These fibres are most apparent in front, where the membrane is ‘much thicker; behind, they are mixed with some longitudinal fasciculi. 6. Corpora Quadrigemina or Bigemina, (Fig. 323, 7, 8.) These are four round eminences, placed in pairs, which surmount the cerebral peduncles behind. The two posterio¥, the smallest, are also named the tubercula testes, and the anterior pair the tubercula nates. The posterior corpora quadrigemina, or tubercula testes, are related, in front, with the anterior eminences : behind, with the anterior cerebellar peduncles and the valve of Vieussens, from which they are separated by a transverse age from the bottom of which arise the pathetici nerves. An oblique d unites them, outwardly, to that portion of the optic layer designated the corpus geniculatum internum. The anterior corpora quadrigemina, or tubercula nates, are distinguished from the preceding not only by their larger volume, but by their colour, which is grey, that of the testes being white. They are also rounder, nearer each other, and covered by the cerebral hemispheres; while the posterior rather lie beneath the cerebellum. A curved groove isolates them, in front, from the thalami optici. 7. Thalami Optici. (Fig. 323, 9.) This name is given to that part of the upper face of the isthmus which is situated in front of the corpora quadrigemina. These thalami are therefore placed above the anterior part of the cerebral peduncles. Larger altogether than the corpora quadrigemina, and more so before than behind, each exhibits a grey, slightly convex, and very irregularly ilateral surface, covered by the velum interpositum, which separates it rom the cornu Ammonis (pes hippocampi ), and from the posterior pillars of the cerebral trigonal (fornix). Inwardly, they incline towards each other in forming on the median line a somewhat deep fissure, in which runs, from before to behind, two white longitudinal bands that will be noticed hereafter as the anterior peduncles of the pineal gland. This fissure enters, behind, into the common 680 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. posterior opening (foramen commune posterius); in front, into the common anterior opening (foramen commune anterius) : Y nes which will be described — with the interior of the isthmus. #2 Outwardly, the thalamus optici shows two prominences called the corpora — geniculata, from which arise the second pair of nerves; placed one before the other, the posterior nearer the middle line than the anterior, these two 2 projections are distinguished as external and internal. The corpus genicu- latum externum is always more voluminous, better defined, and situated ona Fig. 324. LATERAL VIEW OF THE ISTHMUS. 1, Medulla oblongata; 2, Corpus restiforme; 3, Lateral fasciculi of the medulla oblongata; 4, Inferior fasciculus, or corpus pyramidale; 5, Pons Varolii; 6, Middle peduncle of the cerebellum ; 7, Cerebral peduncle ; 8, Testis ; 9, Natis ; 10, Corpus geniculatum internum ; 11, Corpus geniculatum externum; 12, Optic nerve; 13, Fourth nerve resting on the band of Reil; 14, Sensitive root of the ~ trigeminal nerve; 15, Its motor root ; 16, Facial nerve; 17, Auditory nerve. more elevated plane than the internal corpus geniculatum, which is united to the posterior corpora quadrigemina by an oblique band (Figs. 323, 10; 324, 11 Behind, the thalami optici appear to be notched to receive the nates, which they slightly inclose. In front, they are separated from the corpus striatum by a groove, at the bottom of which is a narrow strip named the semicircular band (tenia semi- — circularis). 8. Pineal Gland or Conarium. (Fig. 323, 14.) This name has been given to a small tubercle of a reddish-brown colour, in the form of a pine-cone, enveloped by a Tie agora of pia mater from the velum interpositum, with its apex upwards, and its base resting on the common posterior opening, which it closes, and around which it is attachoaa . by a circular lamella. vg From this lamella is detached, in front, two fibrous cords—the anterior - THE ISTHMUS. 681 of the conarium (or habenw). These (Fig. 323, 15) are two narrow white bands, which commence at the base of the pineal gland, and are directed forward parallel to each other, in the bottom of the fissure of the thalami optici, to which they firmly adhere. On arriving at the anterior common opening, they become attached to the anterior pillars of the cerebral trigonal (or crura of, the fornix). Sometimes they are very narrow and by an interval; but more frequently they are relatively wide, and immediately in contact on the median line. The conarium is far from always offering the same volume; it has been exhibited in its usual dimensions in Figure 323, and in Figure 327 it is shown as incomparably larger. The structure of the pmeal gland appears to be very simple, and only one substance of a brownish-grey colour, apparently amorphous, ‘and sometimes studded with calcareous granulations (acervulus), but with- out any internal cavities. This organ and that whose description follows, do not belong, properly ing, to the system of the encephalic isthmus; but are rather, as we have already said, appended glands, which merit to be described apart, the same as the three immense cerebellar and cerebral ganglia. If we have studied them in this place, it was only for the sake of simplification. 9. Pituitary Gland. (Figs. 322, 8; 327, 19.) The pituitary gland, also named the hypophysis cerebri and suprasphe- noidal appendage, is a small disc-shaped tubercle, fixed to the anterior extremity of the interpeduncular fissure by the pituitary stem (infundibulum) and the tuber cinereum. a. The tuber cinereum is a little eminence of a grey colour, situated in the middle line, between the corpus albicans and the chiasma of the optic nerves, at ‘the anterior limit of the encephalic isthmus. This emi- nence is hollow, and its cavity is nothing more than a diverticulum of the middle ventricle. b. The infundibulum is only a short conical prolongation, whose base is attached to the tuber cinereum, and its apex to the superior face of the pitui The cavity of the tuber cinereum is continued into the infundibulum, and terminates in a cul-de-sac towards its summit. This rolongation, also formed of grey substance, is distinguished by its great ity ; so that it requires some care to preserve it intact when opening the cranium at its base. ¢c. The pituitary gland is lodged in the sella turcica, where it is en- veloped by the suprasphenoidal duplicature of dura mater; it is a small, nearly circular body, flattened above and below, and more or less thick, according to the subjects. Its inferior face rests on the sphenoid bone through the medium of the dura mater, to which it is strongly adherent; the superior covers the corpus albicans, with a portion of the cerebral peduncles, and in front receives the insertion of the pituitary stem. Its circumference responds to the supra- sphenoidal duplicature, whose interior forms the cavernous sinus. There is no cavity in the pituitary gland. The matter composing it appears to be almost amorphous; it is yellow in the anterior half of the organ, and brown in its postérior portion. 682 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. INTERNAL CONFORMATION OF THE IstHMUS. (Fig. 327.) The encephalic isthmus is hollowed at the thalami optici by a eng al cavity, named the middle (or third) ventricle, which is extended back beneath the corpora quadrigemina by a canal—the aqueduct of 8 ? this opens, below the valve of Vieussens, into the posterior (or en vel ci + tricle—another cavity comprised between the cerebellum and medulla — oblongata. These three diverticuli will be studied in succession. 4 | a 1. Middle Ventricle, or Ventricle of the Thalami Oplici. (Fig. 327, a5 | ag The middle ventricle is an irregular cavity, elongated from behind to” before, depressed on each side, and offering for study two walls, a floor,a — roof, and two extremities. ; The two walls are smooth, nearly plane, or very slightly concave from ~ above to below. The floor is extremely narrow, and only forms a channel whose bottom — corresponds to the interpeduncular fissure, which is nearer in front than — behind, and to the corpus albicans and tuber cinereum, The cavity of — the latter (Fig. 827, 20), prolonged into the pituitary stem, communicates — with the middle ventricle, and assists in its formation. - The roof, as narrow as the floor, and, like it, nothing but a channel, is — constituted by the two thalami optici which are joined to one another above — the ventricle, forming a thick grey commissure (Fig. 327, 16). It is Papo, at its extremities by the two orifices already at as the posterior — and anterior common foramina. The posterior common foramen (Fig. 327, 15) commences be- — hind the grey commissure, and — terminates at the base of the pineal gland by an irregu- larly expanded ae Ie is limited behind by the p terior white commissure, a ‘ fasciculus of transverse tres placed in advance of the cor- pora quadrigemina, above ‘thea TRANSVERSE SECTION OF THE ENCEPHALON AT entrance to the aqueduct of 4 1 et an BEI (oiler ta a , Po hetanee foumine quartum ventriculum), and whose ovale of Vieussens; 2, 2, Grey substance forming _ the external layer of the convolutions ; 3,.Section extremities are lost in the sub-— of the corpus callosum; 4, 4, Interior of the Stance of the thalami optic lateral ventricles; 5, Section of the great vena (Mig. 325, 9). The anteri Galeni; 6, 6, Cerebral peduncles; 7, 7, Section of ¢ommon foramen, also denis the isthmus; 8, Posterior common foramen ; 9. Posterior white commissure ; 10, Entrance to the nated the foramen of Me aqueduct of Sylvius, (and iter ad infundibul ) (Fig. 327, 14), is the medi . of communication between the middle and lateral ventricles, and afford a passage to the vascular cord which unites the two choroid plexuses. Tt is i Fig. 325. THE ISTHMUS. 683 in front of the grey commissure, beneath the summit of the fornix, whose two pillars concur to circumscribe it, and between which is seen the anterior white commissure. This is a small band of white transverse fibres, analogous to that which constitutes the posterior commissure, but stronger, ing in front of the anterior pillars of the fornix, its extremities entering and becoming lost in the corpus striatum on each side. The posterior extremity of the middle ventricle, narrower than the anterior, and placed on a more elevated plane, is continuous with the aqueduct of Sylvius, whose entrance (Fig. 325, 10) is beneath the pos- terior commissure, towards the common foramen. The anterior extremity, more dilated than the posterior, is situated _ immediately above the optic chiasma, and is only separated from the bottom of the great interlobular fissure of the brain by a small and very thin grey lamina attached to that chiasma, and for this reason named by writers the grey root of the optic nerves. This lamina (lamina cinerea) is readily seen when the optic commissure is turned down on the pituitary gland; it is sufficient to traverse this to enter the middle ventricle. The ependymis, which lines the central canal of the medulla spinalis, also covers the walls of this cavity ; through the aqueduct of Sylvius, it is oes into the posterior (or fourth) ventricle ; by the anterior common into the lateral ventricles, and thence into the spaces in the middle of the olfactory lobes. 2. Aqueduct of Sylvius, (Fig. 327, 6.) This is a longitudinal median canal passing beneath the corpora quad- rigemina, and above the peduncles of the brain. Its anterior extremity communicates with the middle ventricle, and the posterior opens below the valve of Vieussens into the cerebellar (or fourth) ventricle. 3. The Posterior or Cerebellar Ventricle. (Fig. 327, 5.) This ventricle’ (or sinus rhomboidalis), situated beneath the cerebellum, between its peduncles, and above the medulla oblongata and pons Varolii, is a cavity elongated from before to behind, and almost entirely occupied by the vermiform processes. Its superior wall is formed by these two processes, the valve of Vieussens, and that of Renault. The inferior, or floor of the cavity, is represented by the excavation on the superior face of the medulla oblongata, and which is prolonged in front, above the pons Varolii, to near the testes. The anterior extremity communicates with the aqueduct of Sylvius. The posterior occupies the summit of the calamus scriptorius. STRUCTURE OF THE ISTHMUS, The encephalic isthmus being only a prolongation of the spinal cord, ought to resemble it in its structure; and this is, in fact, what is observed, aly in its posterior part, the common features of their organisation isappearing as we approach its anterior extremity. what has been said as to the external conformation of the medulla oblongata, we know that this organ presents, on each of its lateral halves, traces of a division into three principal fasciculi: a superior, formed by * As the cerebellum coneurs in the formation of this cavity it would perhaps be better to defer its study until that organ has been described. 684 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. the corpus restiforme; an inferior, represented by the corpus p and the third, or intermediate of the other two. "Phese three psciaalial only the continuation of those we have recognised in the cord itself, pe =! whose properties they share—the first being sensitive, and the others motor, — Fig. 326. The superior fasciculus, or corpus restiforme, lying, at its posterior extremity, beside i> fellow of the opposite side, is separated from it for the greater part of its extent by the excaya- tion that constitutes the floor of the fourth ventricle. It rests on the external part of the lateral fasciculus. At the extremity a the pons Varolii is given off a small branch that forms the terior cerebellar peduncle ; then continues its course on ‘ao side of the posterior ventricle, — soon joins the anterior cerebellar peduncle, which is above it, and DISSECTION OF THE MEDULLA OBLONGATA, sHowING With it passes beneath the cor- THE CONNECTION OF ITS SEVERAL FASCICULI, OR pora quadrigemina. , STRANDS. The inferior fasciculus, the A, Corpus reevant b, ee opticus; C, D, si thinnest of the three, comprises, — pora quadcrigemina ; E, ommissure connecting them with the cerebellum; ¥F, Corpora restifor- as has been said, all that portion . + mia; P, P, Pons Varolii; st, st, are tract ; of the bulb which constitutes ‘mt, mt, Motor tract ; g, Olivary tract ; p, Pyrami- the pyramid. But when this — dal tract ; og, Olivary ganglion ; op, Optic nerve; eminence is null, or but slightly 3m, Root of third pair (motor); 5s, Sensory root marked, we ought to recognise of the fifth pair. the limits which separate it from the lateral fasciculus by the line of insertion of the roots of the great hypoglossal nerve, supposed to be prolonged to the pons Varolii, near the point of emergence of the external motores oculorum - nerve. Tts fibres partly intercross with those of the opposite fasciculus, in the bottom of the middle fissure. They all pass above or across the transverse fasciculi of the pons, to constitute the inferior plane of fibres of the cerebral — peduncles. The lateral or intermediate fasciculus of the bulb, comprised between the — line of insertion of the hypoglossal nerve-roots, and those of the motor roots — proper to the glosso-pharyngeal, pneumogastric, and spinal nerves, differs — but little from the inferior cord. By a portion of its upper face it forms — the floor of the fourth ventricle. After leaving the pons Varolii, like the pyramidal fasciculus, it goes to assist in the formation of the cerebral — peduncles, and particularly of their triangular oblique fasciculus. «a In examining, collectively, at these peduncles, the medullary fasciculi. prolonged into the isthmus, we observe nearly the same order of superposition — as in the bulb; but it is no longer possible to distinguish them clearly from each other, they being confounded with those of the opposite side. Their fibres can be seen prolonged in a mass beneath the corpora quadrigemina, across the proper substance of the thalami optici, and passing into the corpora striata, to disappear on each side, like a fine expanding sheath, in th . middle of the cerebral hemispheres. > THE ISTHMUS. 685 _ To this important system of white longitudinal fibres—a prolongation of those of the spial cord—is found annexed as complementary elements in the organisation of the encephalic isthmus, several systems of transverse fibres— also white—and masses of grey substance. The following is a summary so Sapa of the arrangement of these new elements. In proceeding from ind to before, we notice, among the white transverse fibres : 1. The expansion of arciform fibres which sometimes covers the inferior face of the bulb (Fig. 338, 7): their superior extremity is lost in the corpus restiforme; the inferior is buried in the intermediate fissure of the _ pyramid and the lateral fasciculus. 2. The proper fibres of the pons Varolii: they constitute a very thick semicircular fasciculus whose extremities form the middle cerebellar es and enter the cerebellum; this fasciculus envelops, inferiorly and laterally, the longitudinal fibres of the isthmus; it is crossed by several planes of transverse fibres. 3. The transverse fibres of the valve of Vieussens and those of the white commissures, which have been already noticed. The grey substance of the isthmus, which now remains to be mentioned, is far from being so abundant as the white substance, and, as in the spinal cord, it is principally deeply buried in the texture of the organ. In the medulla oblongata none is found on the track of the superior and inferior fasciculi of fibres; but the lateral fasciculi are intermingled with it, and there is a layer on the floor of the fourth ventricle. It is also found in the cerebral peduncles, and particularly in the prolongation of the lateral fasciculi of the bulb. Each of the corpora quadrigemina is composed of a small mass of this grey substance, and is covered by a thin pellicle of white matter which is searcely perceptible in the anterior eminences. The optic thalamus is a similar mass, though more voluminous, darker coloured, and without a layer of white substance on its superficial face. Lastly, nerve cells also exist between the various layers of transverse fibres of the pons Varolii, and between the tubes which constitute the valve of Vieussens. DIFFERENTIAL CHARACTERS IN THE ISTHMUS OF OTHER THAN SOLIPED ANIMALS, : eet from its volume, the isthmus does not present any sensible differences in and the Pig. In the Ox, it is remarked that: 1, The inferior mids of the medulla oblongata are more prominent, and the transverse cords parallel to the pons Varolii more voluminous than in Solipeds; 2, The erura cerebri are short ; 5, The optic nerves are larger than in Solipeds; 4, There is a largely developed pituitary gland, excavated by a wide cavity, and flattened from above to below; 5, Lastly, the testes are more conical and less distinct from the nates than in the animals already studied. In the Carnivora, the fourth ventricle is very large and deep, and bordered by salient and detached corpora restiformia. _ Its floor is marked by some white transverse strie. The pons Varolii is large; the cords (or columns) of the medulla.oblonyata, lel to its ior border, are as developed as in the Horse, without taking into consideration the difference in size of the two species. The pyramids are voluminous, and the olivary bodies well defined. The festes are larger than the nates, COMPARISON OF THE ISTHMUS OF MAN WITH THAT OF ANIMALS. In human anatomy, the medulla oblongata and encephalic isthmus are described tely. The feat shows on its lower face a well marked groove, a continuation of that of the spinal medulla; it terminates anteriorly in a deep fossa named the foramen cweum of Vieq-l Azyr. The pyramids are well marked, The ol/vary bodies are much more 686 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. prominent than in animals, and are also distinguished by the presence of a nucleus in their interior, The medulla oblongata of Man has not the transverse b behind the pons Varolii, which we described in the Horse (Fig. 333). With regard to the isthmus proper, if contains the parts in front of ue mela oblongats already studied in the domesticated animals. The pons Varoli¢ is the crura cerebri are separated from each other _by a groove. at the bottom of which are i” several small openings. The fourth ventricle is deep, is bordered by we corpora restiformia, and inclosed posteriorly and laterally by the valves of Tarin (e medullare posterius). On its floor are remarked transverse strise (line: transverse) Nes the barbs of the calamus scriptorius, which are also found in the Dog. The testes are smaller than the nates ; but the difference in their volume is less considerable than exists between Solipeds and Ruminants. Their structure is already known. Articte ITT.—Txe Crerrpetivm. The cerebellum, or posterior enlargement of the encephalon, is the single mass supported by the isthmus, separated from the cerebrum by the transverse partition constituting the tentorium cerebelli, and lodged in the posterior compartment of the cranial cavity, which almost exactly gives the measure of its volume, ) | 1. External Conformation of the Cerebellum, The cerebellum, isolated by dividing its lateral peduncles from the medullary prolongation on which it is fixed, presents the form of an almost globular mass, slightly elliptical, elongated transversely ; while its external surface is furrowed by a great number of sulci, the two principal of which © (sulci horizontalis) pass in a circular manner on each side of the middle line around the organ, dividing it into three lobes—a middle and two lateral. The three lobes of the cerebellum are not always readily distinguished from each other, in consequence of the shallowness and irregularity of the two sulci separating them. We will, nevertheless, study them in succession, and afterwards examine, in a general manner, the farrows on their superficies, Middle lobe (Fig. 321, 2).—This has been compared to a sti rolled in a circular manner around the middle portion of the cerebellum, and whose two extremities are joined, without being confounded, below the inferior face of the organ. . This vermicular disposition is not well defined in the middle and superior portion of the cerebellum, where this lobe is always more or less subdivided into large multiple and irregular lobules; but it is better observed before and behind, in those points which correspond to the two — extremities of the animal selected as a term of comparison. There may be remarked two longitudinal eminences transversely annulated on their surface, and curved beneath the cerebellum in such a way as to come in — contact with each -other. These eminences constitute the anterior and posterior vermiform processes, Their extremities are lodged in the fourth — ventricle, whose roof they concur in forming. On the anterior vermiform process the posterior border of the valve of | Vieussens is inserted. The posterior vermicular process also receives the insertion of a valve already mentioned, and which must be again briefly referred to. This valve, described for the first time by M. Renault,’ forms a lamina of a certain thickness stretched above the calamus scriptorius. It has exactly the triangular form of this space, and presents a superior face covered by the (' The late eminent veterinary teacher and director of the Alfort School.) 687 THE CEREBELLUM. . b and to its lateral parts mding to the receding angle of the excavation. ior vermiform process rest small vascular loops prominence, =a~+¥Y of ote - Ss 3 om 2 eS Sata sa mer 35 gssisaee Bhyad 2 og Rea SE efse-eagut PHS ESS 2Oo% ow 2 e*. sSfe Hoe —~Sss 23 SLEREsSe i 7 o8 Beafanes BSE ee = ca a 2 S's. 4 83-5 cE he pees. e"a SCP Bo en so Ss G¢.2 fod Bling PE Se i ees ASES 22 ¢ a= = So ae @ gs = 923323 ® ons 4 S 8 3 r=) At 2 Hw” ee = YS 2 Ze ama 33 with an evident dependency of the pia mater-—the plexus choroides.} the cerebellar ventricle. 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UoyVy su Saravzp siq7 YoryA wor woureds oy} Uy sum qq se snousumyoa sv st 41 {puels peourd ey3 Jo uooag ‘oT Ssndurvooddry oy Jo Azrutesyxe puarezuy “6 * sTyUN ‘g {prearoy yonut 00} aav 41 wo1y Surpesdord oul, oy} puv cindy oy}—stassnat, Jo Alva oy} Jo MOTpeg ‘L Sez 1oq1¥ ayy Suraoys ‘urmj[aqere0 UIVAUOTGO Vj[Npeut ey} JO WoFIeg ‘T XVIGaK $sntaphg Jo yonponby ‘9 { umyfeqatao oy} Aq petodoo ojoltjuaa Iol10480, “¢ ay} JO OFC “F 11qQere0 vant oy Jo 0491 “Gg * POIVA suod ay} Jo o94Iq ‘Z ¢ ‘NOTVHdAONA AHL JO NOLLOAS ‘IVOMLUAA AONV lar ed and lobulated in every direction, irregu .—These are shaped like two 3, 3) heir surface, f ‘ e Lateral lobes (Fig. 321, segments ofasphere. ‘I issur ‘ It is by ally, superiorly, or posteriorly. tum is represented in the rudimentary state in Man, by the vavule Tarin/. presents nothing interesting extern ' This 688 TUE CENTRAL AXIS OF THE NERVOUS SYSTEM. their inferior part that the peduncles enter the substance of the cerebellum ; ; and behind this point, beneath their lateral parts, the cerebellar plewus choroides is applied. , The cerebellar choroid plexuses.—--This name is given to two small reddish — granular masses, formed of vascular loops, elongated from before to eee % depressed above and below, and comprised at their internal borders between — the corpora restiformia and the inferior face of the lateral lobes of the — cerebellum, to which they are strongly adherent by their superior face. — These two plexuses are joined together by means of Renault's valve, which — is united to them towards its base. Sulci and lobules of the cerebellum.—On examining, in a manner, all the sulci which intersect the external surface of the cerebellum, — 4 we see that they penetrate to very unequal depths in the substance of the — organ, and that they divide it into successively decreasing segments, of which Figs. 324 and 327 may furnish a sufficient idea. There is at first a certain number of principal lobules, which are divided into secondary lobules; and these, again, are in their turn separated into short lamelle, representing the extreme limits of cerebellar lobulation. 2. Internal Conformation and Structure of the Cerebellum. | The cerebellum concurs, by its inferior plane and the internal face of its peduncles, to form the cavity already described as the posterior or cere- bellar ventricle; but in the mass of the organ itself there is no trace of excavation or other peculiarity. This is demonstrated in the most evident manner by sections of its substance made either in an antero-posterior or in a transverse direction. We only see in these traces of the sulci which divide the organ into lobules; and they also afford evidence as to the structure of the cerebellum, showing that, like all the other parts of the cerebro-spinal axis, it is formed of white and grey substance, The latter, spread over the entire surface of the organ, constitutes the cortical layer of the different segments of which it is composed. It is even prolonged into the convolutions which increase the surface-extent of the cerebellum ; in each lobule it may be decomposed into superposed layers, parallel to the lamina of white substance that forms the nucleus of the lobule ; between these layers of grey substance is a very thin mass of white matter. The white substance, enveloped on every side by the grey, forms two thick nuclei occupying the centre of the lateral lobes, and which are united and confounded on the median line in the texture of the middle lobe. These two nuclei, in continuity on each side with the oor peduncles, are only their prolongations or intercerebellar portions. ey a send into the middle of each principal lobule a long and thick branch, which gives off smaller divisions that ramify in the secondary lobules, and from which escape a new series of ramuscules that enter the smallest segments ; this gives to the cerebellum a beautiful arboreal aspect, justly designated by the older anatomists the arbor vite. (See Figs. 824, 827, 329, for — representations of the arbor vite cerebelli.) In the interior of these nuclei, a little in front, there sometimes exists a — small, slightly-grey spot; this is the trace of the corpus rhomboideum (or dentatum of Man). Ss The nuclei of the white substance of the cerebellum are constituted, like z, the matter of the medulla, by nerve-tubes which are continuous on one side THE CEREBRUM, =" nerv' _ ___ With regard to structure, the grey matter of the cere- bellum may be decomposed into two layers; the super- ficial is very rich in blood-vessels, has a greyish tint, and is composed of large nerve-cells and smaller rounded ele- _ ments; the deep layer is of a yellow colour, and also contains nerve-cells and round elements, though the latter _ are smaller than in the other layer, and have been sometimes _ mistaken for simple nuclei. DIFFERENTIAL CHARACTERS OF THE CEREBELLUM IN OTHER THAN SOLIPED ANIMALS, _ The external and internal conformation of the cerebellum offers the closest analogies in the domesticated mammifers. In all, its with that of the other encephalic lobes, is not hus, while the relation between the weight of the cere- bellum and that of the brain of the Horse is as 1 to 7; with the Ox itis as 1 to 9; with the Dog 1 to 8; with the Cat 1 to 6; and with the Sheep 1 to 3. These are the only differences to be noted. animals ; though, in proportion 'to the cerebral ag i it ing as : a free projection in which is the fourth ventricle; this is the uvula of the cerebellum. The uvula is connected at each with the valves of Tarin: lamin of nerve-substance lodged for most part in tle fourth ventricle, and hidden by the lower face the cerebellar hemispheres. The latter constitute, on the sides of medulla oblongata, two prominences situated one below the other, ve the crura cerebelli; the first is designated the amygdala or msil, the second the pneumogastric lobule (or flocculus). parE EF Arricte IV.—Tue Crereprum. _ The cerebrum, the principal portion of the encephalon, comprises the two anterior lobes or hemispheres of that apparatus: enlargements which are elongated in the direc- tion of the great diameter of the head and cranial cavity, lie beside each other on the middle line, and are united ‘at their central part by a transverse commissure, and by into their substance. 689 with the crura cerebelli, and on the other terminate in the cells of the grey ‘Inthe grey spot that forms the corpus rhomboideum, is a great number of Fig. 328. SECTION OF THE CORTICAL SUB- STANCE OF THE CEREBELLUM, a, Medullary sub- stance, showing its fibres; b, Sub- stantia ferrugi- nea, composed of fibres and cell- nuclei; ¢, Grey surface, granu- lar at the sur- face, and contain- ing large mul- tipelar branch- ing cells near the substantia ferruginea. the encephalic isthmus, whose anterior extremity penetrates, inferiorly, (See Fig. 829 for a good idea of this penetra- : ti ‘hose two lobes together represent an ovoid mass, having its thick extremity adjacent to the cerebellum ; it is depressed from above to below, deeply divided above, in front, and behind by a median antero-posterior 2¥ 690 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. fissure, and receiving in the middle of its inferior face the insertion of tl cerebral peduncles. This mass, seven to nine times more voluminous than the cerel fills the anterior compartment of the cranial cavity, and thus occupies t : greater portion of that space. * It exhibits for study its external conformation, its internal conformation, and its structure. aasey ANTERO-POSTERIOR AND VERTICAL SECTION OF THE ENCEPHALON TO ONE SIDE OF THE MEDIAN LINE. 1, 1, Isthmus of the encephalon; 2, Medulla oblongata; 3, Pons Varolii; 4, Cerebral peduncle ; 5, 6, Corpora bigemina ; 7, Optic thalamus ; 8, Pituitary ‘gland ; 9, Pituitary stem : 10, Optic nerve ; 11, Cerebellum ; 12, 12, Cerebral hemisphere ; 13, Ventricle of the hemisphere ; 14, "Corpus striatum ; 15, Cornu Ammonis; 16, ‘Olfactory lobe; 17, Ventricle of the olfactory lobe. EXTERNAL CONFORMATION OF THE CEREBRUM. f Instead of examining the organ in mass, with regard to its external con- formation, we will first consider the great interlobular (or longitudinal) fissure — which divides it lengthways; and afterwards study its two lateral halves, — or cerebral hemispheres, which in reality constitute two symmetrical organs, r 1. The Longitudinal Fissure. This fissure exists throughout the vertical and antero-posterior cireum- _ ference of the cerebrum, but does not everywhere offer the same disposition, — On the superior aspect of the organ it is very deep, and when the two | hemispheres are separated to discover its extent, we see that it reaches to the upper face of the great commissure—the corpus callosum. Behind, it curves between the posterior lobes of the hemispheres, but without corres- ponding directly with the posterior thick rounded margin of the corpus — { callosum, above which there is a feeble adhesion established between the — two halves of the cerebrum, forming a kind of bridge. But in front it passes — to the anterior margin of this commissure, and is prolonged in the interval” of the anterior lobes of the hemispheres to reach the inferior face of the — organ. . Riakoad inferiorly, the interlobular fissure is well defined ‘in front, THE CEREBRUM. 691 where it attains the anterior border of the corpus callosum; but behind, on _ leaving the chiasma of the optic nerves, and which marks the anterior limit | of the isthmus, this fissure appears suddenly to stop. This is because it 3 mg considerably enlarged, and is changed into a vast notch which admits the anterior extremity of the isthmus: or rather, it bifurcates to pass on each side between the hemisphere and the anterior extremity of the =. prolongation, at first crossing the optic nerve, then turning round the cere peduncles and corpora bigemina, above which its branches unite, and are confounded with the undivided part of the fissure, which _ separates the posterior lobes of the hemispheres. There exists, then, around the point of immergence of the isthmus in the cerebrum a well-marked line of demarcation, which constitutes, above and laterally, a very deep fissure in which is imbedded the vascular expansion hk as the velum interpositum ; this aperture is designated the fissure of Bichit, or great (transverse) cerebral fissure. _ The interlobular fissure receives the longitudinal septum of the dura mater—or falx cerebri. It also lodges arteries and veins, among which it is necessary to distinguish the great vena Galeni, which ascends from the bottom of the fissure, after passing round the posterior border of the corpus 2. The Cerebral Hemispheres, . _ Each hemisphere or lateral moiety of the cerebrum, represents an ovoid segment, in which we may consider four faces and two extremities, _ ‘The superior face is convex, and is covered by the roof of the cranium, which is formed by the frontal and parietal bones. The external, equally convex and insensibly confounded with the adjacent faces, responds to the lateral walls of this cavity: that is, with the * pepe portion of the temporal bone, the parietal and frontal bones, and ala of the sphenoid. The inferior, irregularly mammillated, rests on the sphenoid bone. The internal is plane, and for the greater part of its extent is related to the other hemisphere through the medium of the falx cerebri; it is in its central and inferior portion that the union of the two halves of the cerebrum takes place, by means of the great cerebral commissure and the anterior extremity of the isthmus. The posterior extremity of the hemisphere corresponds to the cerebellum, which slightly depresses it, and from which it is separated by the transverse septum of the dura mater peapriapag ___-‘The anterior extremity or lobe is lodged in the fossa formed on each side of the crista galli by the frontal and sphenoid bones. - ‘The anatomical peculiarities to be found in these different regions of the external surface of the hemisphere are: 1, On the inferior face, and from before to behind, a detached appendage constituting the olfactory or ethmoidal lobule, a transverse groove named the fissure of Sylvius, and an elongated eminence called the mastoid lobule ; 2, Everywhere else, the cerebral convolu- tions—depressed elevations curved about in a thousand ways, and separated by sulci of varying depth. We will study these peculiarities in an inverse order to that of their enumeration. 1, Crresrat Convotvutions (Figs. 321, 322, 327).—The cerebral convo- lutions are constituted by the folding of the external surface of the brain, apparently with the intention of considerably augmenting the wae of that Y 692 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. surface. These folds, which are very deep, are extremely irregular; on t surface of the hemispheres their disposition somewhat resembles 1 ) convolutions of the intestines, a circumstance to which they owe their designation. In Solipeds their number is considerable, and not inferior in this respect to those on the human brain. Notwithstanding their great irregularity, the cerebral convolutions off a somewhat constant arrangement; so that it is possible to describe them one by one. This has been done in human anatomy ; but it would be need-— less to repeat the task in the case of the domesticated animals. 2. Masrom or Spurnow Losure (Fig. 285, 1).—This is a large pyriform eminence, corresponding to what has been described in Man as the inferior — (or middle) lobe of the hemisphere, and: occupies the posterior part of the — inferior face of the hemisphere. This eminence is curved upon itself, and shows its convexity outwards. Its internal border, which corresponds to the cerebral peduncle, concurs in the formation of the great transverse — fissure. Its large extremity is turned forward, and margined by the fissure of Sylvius. The posterior extremity insensibly disappears on the inner . side of the posterior lobe of the hemisphere. s This eminence ought to be considered as a large projecting convolution. — It is excavated internally by a cecal cavity, which constitutes the bottom — of the posterior or reflected portion of the lateral ventricles. 3. Fissure or Syivius.— Thus is designated a transverse depression situated in front of the optic nerve and mastoid lobule, in which is lodged — the middle cerebral artery. 4, O.ractory or Eramom Losute.—(Figs. 321, 6; 322, 1; 827,26; — 829, 16).—The appendage to which this name is given is detached from the ‘inferior face of the hemisphere, where it arises by two white-coloured — roots; the external of these is continuous with a long convolution that borders the outside of the mastoid lobule, while the internal, the shortest, originates on the inner face of the hemisphere, in advance of the optic © chiasma. Between these roots appears a prominent surface of a triangular form, constituting the extra-ventricular nucleus of the corpus striatum (substantia perforata). The appendage thus formed passes forward, terminating — in an oval enlargement (bulbus olfactorius) extending much beyond the anterior extremity of the brain, to be lodged in the ethmoid fossa. The olfactory lobe possesses an internal cavity, a diverticulum of the lateral ventricle (Fig. 322, 2). Both lobes being regarded as the first of cranial nerves, we will return to their description when studying the encephalic nerves. INTERNAL CONFORMATION OF THE BRAIN, In separating the cerebral hemispheres by their upper face, we discover the great commissure known as the corpus callosum: the first object that % presents itself for study in the internal conformation of the brain, ! If we afterwards remove, by a horizontal section, and with a instrument, all that portion of the hemispheres which covers this commi 4 and alsoif the latter be excised toa certain extent to the right and left of the median line, we will penetrate two symmetrically disposed cavities in the centre of each hemisphere. These cavities are the lateral or coma ventricles. They are separated on the middle plane by thin partition—the sept lucidum, which is attached to the corpus callosum by its upper border, —_ fixed by its inferior border into the fornix, a kind of median arch benes positum. characteristics of all these parts. The | hemispheres. middle line. The inferior face is divided by the insertion of the sep- tum lucidum into two lateral por- tions, each of which forms the roof of one of the cerebral ventricles. The two lateral borders of the corpus callosum disappear in the central substance of the hemis- where it is almost impos- sible to distinguish their limits. The ior extremity appears at the bottom of the interlobular fissure, after the destruction of the adhesion usually established above it between the two hemispheres, in the form of a thick, er en- largement lenium) folded in genu, lhe confounded with the middle of the fornix. It is prol laterally, above the ventricular cavities, by forming two angles (linew transverse) which are soon lost in the white central sub- stance of the cerebrum. The anterior extremity comports itself in a similar manner between the anterior lobes of the hemi- THE CEREBRUM. 693 foramen of Monro, or orifice communicating with the two ven- the floor of these cavities is observed two large eminences, the ; with a vascular and apparently granu- oid plexus, a dependency of the velum inter- It now remains to enter into some detail with regard to the anatomical 1. The Corpus Callosum. (Figs. 827, 330.) corpus callosum is a kind of arch thrown over the two lateral ven- tricles, while at the same time it is a commissure uniting the two hemispheres. _ It belongs exclusively to mammalia. Composed entirely of white substance, it affects a quadrilateral form, elongated in an antero-posterior direction, and thus presents for study two faces, two borders, and two extremities. superior face, free in the middle, and corresponding to the bottom of the interlobular fissure, is covered right and left by the substance of the It is traversed from before to behind by two white, and sone very delicate, cords, the tractus longitudinalis (the chorde itudinalis of Lancisii) of the corpus callosum, which lie together on the Fig. 330. THE CORPUS CALLOSUM, AFTER REMOVAL OF THE UPPER PORTION OF THE CEREBRAL HEMISPHERES, 1, Centrum ovale of Vieussens; 2, 2, Chorde longitudinales ; 4, 4, Cornua, or angles of the posterior extremity; 5, 5, Ditto of anterior extremity. 2. The Lateral or Cerebral Ventricles. (Figs. 325, 331.) The lateral ventricles are two large elongated cavities excavated in the hemispheres, lying against each other in their anterior moiety, and divergent in their posterior part, which is very much curved backwards, outwards, and downwards, to open into the substance of the mastoid lobule. 694 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. This disposition permits the division of the cerebral ventricles into two regions: an anterior, and a posterior or reflected. ‘Dreey The anterior region is separated in the median plane from the opposite — ventricle, by the septum lucidum and the summit of the fornix, beneath — which is the foramen of Monro establishing a communication between the middle and the two lateral ventricles, and between these latter. Above, it — offers a smooth wall formed by the corpus callosum. Below, on its floor, — there is first remarked, in front, the corpus striatum; behind, the intorial = portion of the hippocampus; in the middle, an oblique groove running from _ behind to before, and without inwards, at the bottom of which floats the — choroid plexus. The anterior extremity of this region, occupied by the base of the corpus striatum, is continued by a narrow opening into the interior of the olfactory lobe. The posterior is prolonged, without any line of demarcation, by the reflected portion of the ventricular sage . The latter region occupies the most declivitous portion of the posterior lobe of the hemisphere, and presents a strongly curved canal whose con- — cavity looks forward; this canal terminates in a cul-de-sac in the substance of the mastoid lobule. On the floor of this canal is delineated the posterior portion of the hippocampus and the choroid plexus. A very fine membrane—the ventricular arachnoid—plays the part of a serous membrane and covers the walls of these cavities, being spread eyery- where over a layer of white substance, prolonged into the ethmoidal diverti- — culum, and continuous, through the foramen of Monro, with that ofthe middle _ ventricle. This membrane secretes a limpid and transparent liquid, analogow to the cerebro-spinal fluid, though in health it is always in small quantity. — 3. The Septum Lucidum. (Fig. 327, 24.) This appellation is given to a thin median lamella, standing vertically between the two lateral ventricles, elongated from before to behind, widened considerably at its anterior extremity, terminating in a point at its posterior extremity, and inserted above into the corpus callosum, below into the of the fornix. ‘sp On the faces of this lamella, which is formed of white substance, is spread the proper membrane of the lateral ventricles. In the human species, — 2 narrow ventricular cavity has been described as found in its substance; but this does not appear to exist in our domesticated animals. | 4, The Fornix (or Trigonum). (Fig. 313, 3.) Also named the vault of three or four arches, the fornix (arch) is a single — and median body in the interior of the brain, concurring to separate the two _ ventricles, and serving to support the septum lucidum. It is depressed from — below to above, and is of a triangular form ; its apex, looking downward, stands _ in the median plane above the foramen of Monro and the thalami optici, — though separated from the latter by the velum interpositum and the hippo-— campi, and receives on its upper face the insertion of the septum lucidum. Behind, towards its base, and on the median plane, the fornix is confounded with the corpus callosum, which it supports; it is prolonged on each side by a lamina extending to the surface of the hippocampus, forming the cortical layer of this deep convolution of the brain, and with its congener constituting the posterior pillars (posterior crura, or corpora fimbriata) of the — fornia. a In front, at its apex, the fornix is also attached to the corpus callos nm, THE CEREBRUM., 695 and divides into two cords or anterior pillars (crura) (Fig. 823, 17), which pass in front of the anterior cerebral commissure, are inflected downwards and backwards, in traversing the optic thalamus, on the sides of the middle ventricle, and, finally, have their extremities confounded with the mammillary process (corpus albicans). _ These two crura limit, in front, the foramen commune anterius or foramen of Monro, over which the apex of the fornix is thrown across like an arch. _ The fornix is white throughout its whole extent, with a greyish tint towards its summit. 5. The Hippocampi. (Fig. 331, 4.) The hippocampus or cornu Ammonis (from its resemblance to a ram’s horn, the crest of Jupiter Ammon), is an elongated projection, a veritable internal convolution of the brain (is, in fact, the internal surface of the gyrus fornicatus or convolution lying upon the corpus callosum, and which terminates at the fissure of Sylvius); it occupies the floor of the anterior region of the lateral ventricle, and is prolonged throughout its reflected por- tion, whose curvature it exactly follows. Considered together, the two hippocampi somewhat closely resemble the uterine cornua of the Cow. _ By their internal extremity, they are in contact with each other beneath the middle portion of the fornix, and above the optic thalamus, which is sepa- rated from them by the velum interpositum (Fig. 327, 9). Their external extremity occupies, in the mastoid lobule, the cul-de-sac of the reflected portion of the lateral ventricle. The central mass of this projection is formed by a nucleus of grey sub- stance, covered superficially by a cortical layer of white—a prolongation of the ior crura of the fornix. _ Yowards the concave border of the hippocampus, this white lamina offers a kind of wide hem, beneath which the choroid plexus passes; this hem constitutes a small curved band, like the cornu Ammonis, wider at its middle part than at its extremities, and is named the corpus fimbriatum, or tenia hippocampus, 6. The Corpora Siriata, (Fig. 331, 7.) The corpus striatum is another projection on the floor of the cerebral ventricle, occupying the anterior region of that cavity. This eminence is pyriform in shape, and obliquely elongated from behind to before, and without to within. Its surface is smooth, and regularly convex. Its base, or anterior extremity, corresponds to the anterior cecum of the ventricle. The summit, or posterior extremity, disappears at the commence- ment of the reflected portion of the ventricular cavity. Outwardly, the corpus striatum is limited by a groove that forms the angle of union between the floor and roof of the ventricle. Inwardly, it is separated from the optic thalamus and cornu Ammonis by another sulcus, in which the choroid somal and which is oblique inwards and forwards, and shows at the the tenia semicircularis (Fig. 323,13). This is a flattened white cord, which disappears inwardly towards the foramen of Monro, and bends outwards along the optic nerve to within about 3-8ths of an inch from the chiasma ; in this way forming a sort of circular band around the anterior extremity of the isthmus, beneath which all the fibres of the latter pass to reach the cerebral hemispheres. : The corpus striatum owes its name to its structure, being composed of a 696 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. thick nucleus of grey substance that crosses the longitudinal fibres of the — encephalic isthmus in passing into the hemispheres ; these fibres appear in several points of this nucleus as very distinct white streaks. a This deep nucleus, which is in- Fig. 331, termediate to the superior A. of the isthmus and the pri > mass of the hemisphere, com ee the entire thickness of the floor of the lateral ventricle, and projects outwards, beneath the inferior face of the hemisphere, between the two roots of the olfactory lobe, where it constitutes the eatra-ventricular — nucleus of the corpus striatum: 80 named in contradistinction to the — oblong eminence in the interior of the ventricle, which is oftende- signated the intra-ventricular nucleus of the corpus striatum, 7. The Velum Interpositum and Choroid Plexus. (Fig. 331, 6.) ANTERIOR PORTION OF THE LATERAL VENTRI- The velum interpositum (velum CLES OF THE DOG, EXPOSED BY REMOVAL or vasculoswm, tela choroidea) is & vas — THE ROOF. cular expansion dependent from the 1, Corpus = poem 2 Peaanebrfe de Ps —_ pia mater, which penetrates the osum, turned [0 er uc- . rate of the septum lucidum, to show the fornix, brain by the transverse fissure, and 3, 3; 4, 4, Hippocampi; 5, 5, Tenia semi- insinuates itself between the tha- circularis ; 6, 6, Choroid plexus; 7,7, Corpora lamus opticus and the convolution striata. of the cornu Ammonis. The velum, on arriving beneath the tenia hip- pocampus, terminates in the choroid plexus: a red, granular-looking cord, which is suspended by its antero-external border, and projects into the interior of the lateral ventricle. : The choroid plexuses of the brain extend from the anterior extremity of — the corpus striatum to the bottom of the cecum in the mastoid eminence or lobule. In the anterior region of the ventricle, they occupy the oblique suleus which traverses that part, to the inner side of the corpus striatum, In the posterior region, they float in front of the cornu Ammonis. Their anterior or internal extremity, more voluminous than the external, always forms a small appendage which remains quite free. They are united to each other, near this extremity, by an intermediate cord, which traverses — the foramen of Monro in passing beneath the fornix. Like the velum interpositum, the choroid plexuses are formed by a net- work of arteries and veins, ‘They are often incrusted in calcareous matter, and may be the seat of more or less voluminous cysts, . The veins proceeding from this vascular apparatus are very voluminous, and by their union form the great vena Galeni, which bends round the ~ splenium of the corpus callosum to reach the interlobular fissure, and pro- ceeds to the sinus of the falx cerebri. Zz THE CEREBRUM. J 697 ' STRUCTURE OF THE CEREBRUM. _ The structure of the brain is certainly one of the most interesting points in the study of the nervous centres; for on a perfect knowledge of it depends the solution of the most difficult problems in the physiology of the nervous system. Numerous attempts have been made to elucidate its intimate organisation; but we must here omit the multitude of secondary details revealed by these researches, and limit ourselves to the essential and fundamental facts. The two substances enter into the texture of the cerebral hemispheres, and both are exactly disposed as in the cerebellum. The grey substance extends over the entire external surface of the brain, and dips into the sulci; thereby augmenting the extent of that surface, and forming the cortical layer of the cerebral convolutions. This layer, it is necessary to remark, though perfectly similar to that of the cerebellar lobules, is not homogeneous throughout its thickness, but may be deecom- posed into several secondary stratified layers, between which are extremely thin lamelle of white substance; one of these lamelle nearly everywhere forms the most superficial pellicle of the convyolutions. _ According to Kolliker, there are six layers in the cortical substance of the brain, and these are disposed as follows: 1, A superficial white layer ; 2, Grey layer; 3, First white streak; 4, Yellowish-red layer, external ion; 5, Second white streak ; 6, Yellowish-red layer—internal portion. all these layers are nerve-cells, but in proportion as F they are pale, these cells are few and small; the cells Fig. 833. ves contain colouring matter in the reddish- é' yellow layers. Everywhere they are furnished with from one to five fine prolongations, which bring them into communication with the very fine nerve-tubes of the cerebral hemispheres. Leecher Clarke gives seven layers for this cortical substance.) In the middle of each hemisphere, the white substance constitutes a considerable nucleus, which, from its form, is named the centrum ovale of Vieussens (Figs. 325, 1; 330, 1), and which is united to that of the opposite side by the great cerebral commissure, or corpus callosum, sending a prolongation into each convolution; thus ex- hibiting the exact disposition of the lateral white masses of the cerebellum, with which the nuclei of the hemi- thoy an have also another point of resemblance, in that to are attached to the cerebral peduncles, as the first are cerebellar. But the latter peculiarity is less evident CORTICAL SUBSTANCE than the others—which are at once obvious in horizontal oF THE cEREBRAL transverse sections of the brain—and can only be "= SPHEREs. clearly demonstrated by the manipulations necessary to % , Medullary — sub- unravel the intimate texture of the white substance. roma bs bya ee In studying this texture in brains hardened by nitrie She ttreak’ com. acid, washed in pure water, and exposed to dry air for posed of horizontal a day or two, we perceive that the white cerebral sub- — ibres; d, Grey layer; stance is entirely composed of fine fibrous lamelle, [> os white diverging in every direction, corresponding by their con- “?“” centric extremity to the centre of the hemisphere, and abutting, by their 698 THE CENTRAL AXIS OF THE NERVOUS SYSTEM. peripheral extremity, on the inner face of the grey covering of the con- volutions. La The fibres of the white substance of the hemispheres are connected with those of the encephalic isthmus, through the latter being prolonged into the texture of the corpus striatum, where they appear either in the form of stria, or as an elongated nucleus, known as the double semicircular centre of Vieus- sens ; they then pass to the outside of the ventricular cavity, and plunge into _ the centrum ovale of the hemisphere, where they are manifestly continued bya portion of the fibres constituting it. It has been said that these fibres, instead of thus disappearing in the hemisphere, ascend at first to the right and left — on the external side of the lateral ventricle, and are afterwards inflected in- wards above that cavity, to join on the median line; and in this wayformthe corpus callosum. I have searched for this arrangement in our domesticated animals, and particularly in the Dog, whose brain is well adapted for study- ing the corpus callosum, but without success. It has always appeared to me that the extremities of the transverse fibres which form this great com- missure are lost in the white substance of the hemispheres, some above, the others below; and I believe I have also seen some of the pedun- cular fibres radiating in the centrum ovale becoming insinuated between the extremities of the fasciculi of the corpus callosum, to gain the superior of the hemisphere, without being continuous in any way with these fascieculi. Some of the nerve-tubes certainly terminate in the corpus callosum; but in this there is nothing extraordinary, as in that layer there are nuclei and some nerve-cells, DIFFERENTIAL CHARACTERS OF THE CEREBRUM IN OTHER THAN SOLIPED ANIMALS, The brain, in the animals now referred to, offers some differences in volume, as might be inferred from what has been said regarding its relations with the cerebellum. In all, its development posteriorly is not so considerable that it covers the latter, which always remains exposed. Its general form varies a little. In the Ox, the hemispheres are proportionately larger posteriorly than in the Horse, but contract suddenly at the fissure of Sylvius, preserving their reduced dimensions in the anterior lobes; the latter are therefore more conical than in Solipeds, The cerebrum of the Dog is regularly ovoid, except at the extremity of the anterior lobes; there the hemispheres become much flattened from one side to the other, and form a kind of spur that enters the ethmoidal fossee. The cerebral convolutions are a little larger in the Ox than in the Horse, but they are also less numerous; they are still fewer in the Pig, and yet less in the Carnivora; we will see hereafter that they are absent in Birds. The particular features of the lower face of the hemispheres are the same in all the species; except that the ofeotny lobes are more pone f than in Solipeds; they are remarkably robe 5 ong in the Dog. The ventricles are the same in all; the floor is always formed by the corpus striat hippocampus, and thalami optici, the roof by the corpus callosum. In the Oz, the band — of the hippocampus is remarkable for its width; in the Dog, the corpus striatum, pro- portionately voluminous, is of a deep grey colour on its surface. 3 COMPARISON OF THE CEREBRUM OF MAN WITH THAT OF ANIMALS, The cerebrum of Man (Fig. eg Bes distinguished by its regularly ovoid shape, and its great development, eget hind, where it covers tlie cerebellum—a feature — never observed in animals. ye 7 -' Viewed superiorly, a cerebral hemisphere is clearly divided into three lobes: an — anterior or Y nay seo: a middle or ephenslaat corresponding to the mastoid lobule of the Horse; anda pied or occipital, covering the cerebellum. The two first are separated — by a narrow, deep, and sinuous fissure of Sylvius. a. The convolutions are larger, and separated by deeper furrows, than those of the Horse, but they are not more numerous. The olfactory lobes arise, as in ania from two orders of roots, but they are small and entirely hidden beneath the inferior face of the frontal lobes, ti THE CEREBRUM. 699 The corpus callosum is very developed, and, above the ventricle, forms, from before to behind, a salient angular prolongation named the frontal cornu and occipital prolongu- tion, or forceps major. There is nothing to note concerning the forniz and seplum lucidum, except that there is a ventricle in the latter which communicates with the middle ventricle by a small aperture, the vulvc. The lateral ventricles offer remarkable differences. They are not prolonged into the olfactory lobes, but possess a diverticulum that enters the occipital lobe, below the forceps major. This space is more or less developed, and terminates in a point ; it is named the ancyroid or digital cavity, and shows on its floor a small convolution which Fig. 333. THE BASE OF THE HUMAN BRAIN. 1, Longitudinal fissure; 2, Anterior lobes of cerebrum; 3, Olfactory bulb; 4, Lamina cinerea; 5, Fissure of Sylvius; 6, Locus perforatus anticus; 7, Optic commissure; 8, Tuber cinereum ;-9, Third nerve; 10, Corpus albicantium; 11, Fourth nerve; 12, Locus perforatus posticus; 13, Fifth nerve; 14, Crus cerebri; 15, Sixth nerve; 16, Pons Varolii; 17, Portio dura of seventh nerve; 18, Middle lobe of cerebrum ; 19, Portio molliss of seventh nerve; 20, Anterior pyramid ; 21, Glosso-pharyngeal nerve; 22, Olivary body; 23, Pneumogastric nerve; 24, Lateral tract; 25, Spinal accessory nerve; 26, Digastric lobe; 27, Hypo- glossal nerve; 28, Cerebellum; 29, Amygdala; 30, Slender lobe; 32, Posterior inferior lobe. has been designated the ergot of Morand (pes hippocampi). The diverticulum and con- volution do not exist in animals. The cornu Ammonis is slightly bosselated on its surface; it is limited, inwardly, by a band, and below this by a grey denticulated lamina, the gyrus fornicatus. “The other portions of the human brain resemble those of animals; so that it is needless to allude to them, 700 THE NERVES. THIRD SECTION. THE NERVES. Tue nerves represent the peripheral portions of the nervous system, and are cords ramifying in every part of the body, having their origin in the medullary axis or its encephalic prolongation. Before commencing their special study, it is necessary to possess a summary notion of the principal distinctions of which they are susceptible, with regard to their origin, distribution and termination. Srrvoture.—The nerves are formed by an aggregation of the nerve-tubes already described. These are grouped in primary fasciculi, which are rectilinear or slightly undulating, and enveloped in a sheath of delicate con- nective tissue—the perineurium. These primary fasciculi are again assem- — bled in bundles to compose secondary fasciculi, which are maintained by a layer of fibrous connective tissue thicker than the perineurium, Fi ; these secondary bundles by their union constitute the nerve, around which the connective tissue becomes condensed, and found the neurtlemma. « Vessels traverse the connective tissue separating the fasciculi from each other; they anastomose in a network whose elongated meshes are parallel with the nerve-tubes, and they are also surrounded by the nervi nervorwm. On the track of certain nerves is observed a greyish enlargement, or ganglion. This is composed of a mass of nerve-cells, which are generally bipolar, and are situated on the course of the tubes. It is not quite known whether some of these tubes are not merely placed alongside the ganglion. Drviston.—Nerves are divided, with reference to their destination, into two principal groups: 1, The cerebro-spinal or nerves of animal life ; 2, The ganglionic or nerves of organic life. CrrEBro-sPINAL Nerves.—These emanate directly from the cerebro- spinal axis, and are divided into two secondary groups: 1, The cranial or encephalic nerves, which originate in the encephalon, and make their exit by the foramina at the base of the cranium, to be distributed almost exclusively in the head; 2, The spinal or rachidian nerves, arising in the spinal cord, and passing to the muscular or tegumentary parts of the trunk and limbs, through the intervertebral foramina. After what has been said in regard to the apparatus of innervation, we know that the fibres composing these cords are distinguished, by their point of origin and their properties, into fibres of superior origin or of centri conductibility, and fibres of inferior origin or of centrifugal conductibility. The first have a ganglion on their course. The cerebro-spinal nerves are exclusively formed of the first description of fibres, and are named sensitive nerves, as they conduct the stimulus which brings into play the sensibility of the brain. They are distinguished as nerves of general sensibility and nerves of special sensations (or sense). The first are destined to convey all stimuli except those determined by light, sounds, or odoriferous particles; the second exclusively conduct the latter. The nerves which are composed only of fibres of the second kind are called motor nerves, because it is they which carry to the muscles the spontaneous stimulus to motion originated by the will. ; Those which are composed at once of motor fibres and fibres of general sensibility constitute the mixed nerves; these form the largest _ category. q THE NERVES. 701 Ganationico Nerves.—These nerves, collectively representing the great me system, form below and on the sides of the spine, two long cords, moniliform by the presence of ganglionic enlargements, and in the constitution of which nearly all the cerebro-spinal nerves concur; their ramifications, frequently ganglionic also, are destined to the viscera of the neck, the thorax, and the abdomen. In these nerves of organic life are found the two kinds of nerve-tubes, or fibres of centripetal and centrifugal conductibility. But these tubes appear to have only very indirect relations with the brain, for the will has no influence over the organs which receive their nervous fibres from the great sympathetic ; and, besides this, in health, the excitations developed in tiese organs are all reflected by the spinal cord, and do not provoke in any way the special activity of the encephalon—they are not felt. As the nerves of the great sympathetic system are principally formed of fine tubes, we ought perhaps to seek in this anatomical condition the cause of the special properties of these nerves; what tends to make this appear likely is the fact, that the cerebro-spinal nerves contain some of these tubes in their elements, and that they share, with the ganglionic ramuscules, the faculty of bringing into play the reflex power of the spinal cord. But this is only a probability, and is unsupported by any direct proof. However this may be, it must be remarked that the special anatomical and physiological characteristics of the sympathetic nerves should not cause them to be considered as a system independent of the first, or cerebro-spinal nerves. The fibres composing both have, in fact, a common origin in the medullary axis, or rather those of the ganglionic nerves emanate from the nerves of animal life. In the considerations which follow, we will therefore omit this distinction of the nerves into two groups. Oxtcrn or tHe Nerves.—We ought to distinguish in these cords their real or deep origin, and their superficial or apparent origin, The latter is represented by the point of emergence of the roots of the nerves, which are ordinarily spread in a fan shape, then united, generally after a very brief course, into a single trunk, which offers at its commencement a ganglionic enlargement, if fibres of general sensibility enter into its constitution. Their real origin is the point of departure of these roots in the depth of the cerebro-spinal axis. This is not well known, perhaps, of any nerve, even of those whose radicles are easily followed into the substance of the neryous centres. Distrisution or Nerves.—The nervous trunks, formed by the radicles of which we have just spoken, issue in pairs from the foramina at the base of the cranium or in the walls of the spine, to be distributed to all parts of the body by dividing into successively decreasing branches. Those among these branches which ramify in the organs of animal life, generally follow the track of the deep vessels or the subcutaneous veins, and are always found most superficial. Their ramescence is effected in a very simple manner, by the successive emission of the fasciculi composing the principal trunks, until they are completely expended. These branches pursue their course nearly always in a direct line; only some, as the ramifications of the two principal nerves of the tongue, describe very marked flexuosities, with the same protective intention as the arteries of that organ. Anastomoses sometimes join these branches to one another; and anastomoses, often enough complicated, unite many nerves together, and form what are called plecuses. But in these anastomoses, no matter how complicated they may 702 THE NERVES, be, there is never any fusion of the nervous ramuccules, but simple aggrega- — tion of their fibres, which always preserve their independence, characters, — and special properties. These anastomoses, then, differ essentially from those of arteries, and never permit two trunks to mutually supplement each _ other when the course of one is interrupted. The nerves destined to the organs of vegetative life, and which arise from the two subspinal chains in whose formation nearly every pair of nerves concurs, comport themselves in their distribution in a slightly different manner. They are enlaced around arteries, forming on these vessels very complicated plexiform networks, and yet the fibres composing them are as absolutely independent as in the anastomoses above described. TERMINATION OF THE NErves.—This point should be examined separately — in the case of the motor and the sensitive nerves: that is, in the muscles and the integumentary membranes. The distinction, however, is not quite so absolute as this, for the muscles always receive some sensitive tubes with their motor filaments. In entering the muscles the motor nerves divide their branches, still appearing as double-contoured tubes. It was at one time believed that these — fibres formed loops (Valentin) in the interior of the muscle, and returned to their starting point. This opinion has become obsolete since the ultimate termination of the nerves has been studied by Rouget, Krause, Fig. 334. MUSCULAR FIBRES, WITH TERMINATION OF MOTOR NERVE; FROM THE GASTROCNEMIUS OF THE RANA ESCULENTA, a, Terminal pencil of a dark-bordered nerve-fibre; 6, Intramuscular naked axis- cylinder; c, Nucleus of the neurilemma; d, Clavate extremities of the nerve; e, Spaces of the muscle-nuclei; f, Terminal knob of nerve, with central fibres and vesicular dilatations of the nerve; Kihne, Kélliker, Engelmann, Conheim (Beale), and others. What is known of this subject is as follows :—The voluminous, double-contoured nerve-tubes which, more or less, cross the direction of the muscular fibres, soon divide and form pale tubes on whose track are disseminated the nuclei, These tubes contain an axis-cylinder and a medullary layer. They pass ontoa ~ muscular fibre in the following manner: the nucleated sheath of the nerve- tube spreads, and is confounded with the sarcolemma ; the medulla suddenly _ stops, and the axis-cylinder expands to form a minute granular mass named the terminal motor-plate. Is this plate situated without or within the sarcolemma? This question is differently answered by histologists; but, THE CRANIAL OR ENCEPHALIC NERVES, 703 however this may be, this plate, which was discovered by Rouget, at first in reptiles, then in birds and mammals, has been studied by several micro- _ graphs, who are agreed as to its existence. There can, therefore, be no _ doubt that it is the ultimate termination of the motor-nerves. The mode of termination of the sensitive nerves varies as they are sensorial or general sensibility nerves. It appears to bedemonstrated that the tubes of the sensorial nerves have at their extremity an elongated cell, - analogous to that from which they started. An idea has been given of this arrangement in describing the olfactive portion of the pituitary mucous The other sensitive nerves have been supposed to terminate by peripheral _ loops, and again by free extremities passing into kind of cell elements. It _ is certain that these two modes exist simultancously ; recurrent sensibility, which Claude Bernard demonstrated in some cranial nerves, proves _ that certain nerves terminate by loops. Our own experiments have shown: 1, That this recurrent sensibility is a general phenomenon belonging to the sensitive nerves of the limbs, and even to all the sensitive ramifications of the spinal nerves; 2, That the recurrent anastomotic loops are formed at different parts along the course of the nerves, either beneath the integument or in its texture, It is, then, proved that the peripheral loops constitute a mode of termination of the sensitive nerves. But this is not the only mode of termination observed. In the papille of the skin, in certain regions— hand, foot, lips, tongue, glands, clitoris—the corpuscles of Meissner, or tactile uscles, are found; these are composed of condensed connective tissue, and are conical, like a pine-cone, the summit towards the periphery. By their - base enters one or more nerve-tubes, that ascend toward the apex in aspiral manner. In the conjunctiva, lips, etc.,are also found rounded bodies analogous in their structure to the tact corpuscles, and which are named the corpuscles of Krause. Lastly, on the course of the collateral nerves of the fingers and in the mesentery of the Cat, are the Pacinian corpuscles: small globular or ovoid bodies formed of several concentric layers of connective tissue, and with a central canal into which penetrates and terminates, by one or more enlargements, a filament from the nerve-trunk (reduced to the axis- cylinder only).' CHAPTER I. THE CRANIAL OR ENCEPHALIC NERVES, Tue cranial nerves leave the encephalon in pairs, magtey disposed to the right and left, and designated by the numerical epithets of first, second, ete., counting from before backwards. Willis, taking for a basis the number of cranial openings through which the nerves passed, divided them into nine pairs, with which he described the first spinal pair, making it the tenth in the series of encephalic nerves. This division being faulty in some respects, it was sought to perfect it, Haller commenced by removing the first spinal or suboccipital pair of nerves to their proper region; then followed Semmering and Vicq-d’Azyr, a Arloing and Tripier. ‘Recherches sur la Sensibilité des Téguments et des Nerfs de la Main.’ (Archives de Physiologie, 1869.) - rs . . ir a a 704 THE NERVES. who doubled the seventh pair of Willis, and reduced his eighth into three distinct pairs, according to considerations derived from the destination and uses of these nerves. The number of pairs of cranial nerves, their order of succession, and their nomenclature was then established in the following — manner : +i 1st pair or olfactory nerves . . _. corresponding tothe Ist pair of Willis, 2nd pair or optic nerves* . . . . . . « + « «© 2nd pair” Se 8rd pair or common motores oculorum nerves. . . 8rd pair _ 4th pair or pathetici nerves . . . . « «. . . + 4th pair — 5th pair or trigeminal nerves . . . . . . . | « Sth pair — 6th pair or abducentes nerves. . . . . . . «| «» 6th pair — 7th pair or facial nerves, © ss kk le SO eS 7th pai 8th pair or auditory nerves sy SOS PS } eS ae 9th pair or glosso-pharyngeal nerves. . . .« 2. se 10th pair or pneumogastric nerves ¢-\jeee wie) a — 1lth pair or accessory or spinal nerves . . . . « . 12th pair or great hypo-glossal nerves . . . . . . 9th pair — In the following table, these nerves are classed according to properties : rhs olfactory nerves. . . . . . « » OF “Jetipainee 1. netted Spe} optic parves gd. be Yc eve ce)! 6 = : ; auditory nerves... + +... © \« 0) ie ae 2. Mixed nerves trigeminal nerves. . . 0 « 6s) 3 es es OO with double | glosso-pharyngeal nerves . . . . . + 9th — roots pneumogastric nerves. . . . . . . 10th — arene motores oculorum nerves . . . o — eticl NOTVES es oy (sen, vhs elke 3. Motor nerves aT dacentes TOECOB 5 oe any ca-stko Cae ee with single facial Nevves .6'5 1. “5 e 34) bw a roots. accessory or spinal nerves. . . . . . Iith — great hypo-glossal nerves . . . . . . 12th — (Sir Charles Bell considered the fourth, seventh, and eighth nerves as forming a separate system, and to be allied in the functions of expression and respiration. In consonance with this view, he termed them respiratory nerves, and named that portion of the medulla oblongata from which they arise the respiratory tract.) : ; One of the characteristics of the cranial nerves being their diversity, it is scarcely possible to study them as a whole, and it is only in their origin that they resemble each other in some points. We therefore confine — ourselves to those general considerations which alone touch this part of their description. . Do the cranial nerves proceed from the three principal apparatus com- — posing the encephalon, or are they furnished by two, or even one of these? — This is the question that should first be discussed. If it is evident to everyone that the isthmus gives rise to the majority of the encephalic — nerves, and that the cerebellum has nothing whatever to do with their © emission, it is not agreed among anatomists as to the part the brain-proper takes in this emission. Two pairs of cranial nerves are indeed considered — by several authors as emanating from the latter organ, while others regard them as derived from the isthmus. According to the first, only ten en- cephalic pairs of nerves belong to this prolongation of the spinal cord, the other two—the olfactory and optic nerves—proceed from the brain; while the second aver that all the cranial nerves without exception arise from he medulla oblongata. Let us endeavour to discover the truth. ae It is certain that this difference of opinion on a point apparently easy of THE CRANIAL OR ENCEPHALIC NERVES. 705 has its source in a misunderstanding, and is really not founded on which are the same for everyone, their appreciation only varying. — is more easy to prove. Look, in the first instance, at the optic _ nerve. This, according to some, proceeds from the corpora quadrigemi and thalami optici ; it therefore arises from the brain. No doubt, if these . ae at the encephalon be considered as a portion of the hemispheres ; “ is is far from proved, and in an anatomical and physiological point __ of view it is not so. As the corpora quadrigemina and thalami optici form 4 of the isthmus, it is natural to look upon it as the source from which _ the second pair of nerves arise. With regard to the first pair, their fibres _ are also connected with those of the isthmus, across the corpus striatum, as will be proved hereafter. But we are far from. denying their connections with the hemispheres (see the description of the first pair), and which are very intimate; though this proves nothing against our opinion. Therefore _ it is, that, in recognising in the disposition of the roots of the olfactory nerve conditions altogether special, we admit that the isthmus of the encephalon is the common point of departure for all the cranial nerves—an important and capital fact, and which constitutes, for the great category of encephalic nerves, a. true family character. _ Among the other points relative to the origin of these pairs of nerves, | are the following: All the encephalic nerves appear to be connected at _ their origin with the fasciculi of the isthmus, whose properties they share. All are equally connected with a centre of grey substance placed in the _ texture of the isthmus, and named by Stilling the nucleus of the nerves. _ The majority originate by converging filaments, the anterior of which come from the brain, and the posterior from the side of the spinal cord. ‘ion of the cranial nerves—Four preparations are necessary to study the nerves : 1, An encephalon extracted after opening the cranium by its base, and hardened _ by prolonged immersion in alcohol or very diluted acetic seid This piece permits the origin of the nerves to be studied (Fig. 322). 2. The su ‘ial nerves of the head; these are the auricular nerves, and the divisions of the subzygomatic plexus, with the suborbital and mental branches, as well ord tr ramuscules of the three nerves of the ophthalmic branch of tbe fifth 8. A piece disposed asin figure 336, for the study of the maxillary nerves. To _ it, the greater part of the masseter muscle should be removed in dissecting the masseteric nerve; the globe of the eye must be extirpated, the orbital and zygomatic processes excised, the two maxillary sinuses opened, and the branch of the inferior maxillary bone chiselled off as in the figure. Lastly, the anastomosis of the facial with the sub- nerve is dissected by cutting away the parotid gland. 4. The deep nerves, including those of the globe of the eye ; this preparation should be made by following exactly the instructions given for dissecting the arteries of the head. Figure 335 will serve as a guide for details. The pneumogastric and spinal nerves, which are not included in these considerations. ~~ should eeeepaned and studied at the same time as the great sympathetic. When treating of the latter, we will refer to them. ~~ 1. First Pair, or Olfactory Nerves. (Figs. 327, 329.) : The first cranial pair is constituted by the olfactory lobes, whose - anterior extremities give off a great number of nervous filaments, which through the cribriform foramina to ramify in that part of the pituitary membrane lining the bottom of the nasal fosse. Each olfactory lobe is connected with the encephalon by two roots, an external and an internal, both composed of white substance (Pig. 322). 22 706 THE NERVES. internal, followed from before backwards, turns round in the interlobular fissure, in front of the chiasma of the optic nerves, to mix with the cere- bral convolutions. These two roots circumscribe a triangular space oc- cupied by the extra-ventricular nucleus of the corpus striatum, which they ie The external commences by a grey-coloured convolution which borders, externally, the mastoid lobule or inferior lobe of the hemisphere. The a | embrace. In brains which have been macerated for a long time in alcohol, — it is easy to see that the fibres of these roots are continuous, in great with those of the corpus striatum, and commence with the fasciculi of the isthmus, which radiate and spread across the grey matter of that body. After the union of its two roots, the olfactory lobe is constituted by a i} . 4 4 an wide white band that passes forward on the inferior face of the hemisphere, and soon terminates in a very elongated oval dilatation lodged in the ethmoidal fossa. This bulb is formed by grey substance on its inferior — face and white substance on the superior. It is said to be a flattened ganglion applied to a band of white substance, which at first represents in — itself the olfactory. lobe. We have already seen that this lobe is hollow internally, and that it communicates with the lateral ventricles of the brain. This peculiarity, added to the special features of its external physiognomy, might, it appears to us, give rise to doubts as to the real nature of the lobes in question. It is evident that these are not nerves, but rather dependencies of the en- 7 cephalon ; and it is only conformable to custom that we describe them here as the first pair of encephalic nerves. The real olfactory nerves are the filaments which arise from the inferior face of the ethmoidal bulb or ganglion, and which traverse the cribriform lamella to gain the mucous membrane of the nose. Their number cor- responds with the ethmoidal foramina. At first very soft, delicate, and easily torn, they are enveloped on their passage through these a 3 by a very strong neurilemma, which gives them great solidity. Some, in ramifying, descend on the septum nasi; others—and these are the most numerous—divide on the ethmoidal cells, where they form fine and more or less plexuous pencils, mixed up with the no less interesting divisions of the ethmoidal branch of the ophthalmic artery. Their terminal extremities do not descend below the upper third of the nasal foss#, but remain con- fined to the bottom of these cavities. These are the special nerves of smell. They receive the impression of odours and transmit them to the encephalon ; and this function, which has been accorded and refused them time after time, has only been decided within the last thirty years. 2. Second Pair, or Optic Nerves. (Fig. 329.) The nerves of vision present for consideration in their interesting study, their origin, course, termination, and properties. There has been much dispute, and there will probably be much more, with regard to the origin of the second pair. But without confining our- selves to an appreciation of the opinions which have pervaded science on this matter, we will describe what we have observed in the domesticated animals. When the encephalic isthmus is isolated from the brain (Fig. 324, 12 and examined laterally, we recognise on its anterior limit the white band that constitutes the optic nerve. Studied at its origin, this band is con-— tinued, in the most evident manner, with the external side of the thalamus — THE CRANIAL OR ENCEPHALIC NERVES. 707 _ opticus, where it forms the two enlargements known as the corpora geniculata. _ This thalamus ought, therefore, to be regarded as the point of departure of _ the nerve that bears its name. But as the external corpus geniculatum is in contact with the natis, and as the internal is united to the testis by a band of white fibres, it is almost certain, according to several authorities, that _ the corpora quadrigemina concur in furnishing the constituent fibres of _ the optic nerves. At first wide and thin, the optic band (tractus opticus) is rolled round the cerebral peduncle from above to below and behind to before, and 4 ually narrows. Arrived at the inferior surface of the encephalon, it is changed into a funicular cord, which unites with that of the opposite _ side to form the commissure or chiasma of the optic nerves; this is only a _ temporary fusion, as beyond it the two nerves reappear, and pass into the _ optic foramen, to reach the interior of the ocular sheath and the bottom the globe of the eye. We will enter into some details on the relations of the optic nerves in the different points of the course we have indicated. In their flat portion, or origin, they are comprised between the cerebral and the hemispheres. From the point where they become free, _ at the inferior face of the encephalon, to the chiasma, they are covered by _ the pia mater, and adhere by their deep face to the superior extremity of _ the peduncles. coll he chiasma is lodged in the optic fossa, and receives on its deep face the insertion of the small grey lamina which bounds the third ventricle in front; for which reason this is generally described as the grey root of the optic nerves. But of all the proper connections of the chiasma, the most important are certainly those which each nerve maintains with its congener at their junction. What becomes of the fibres of each nerve in this anas- tomosis? Do they cross one another to reach the opposite eye; or do they merely lie together, and afterwards separate, in order to go to the eye on their own side? Anatomy demonstrates that the fibres of the chiasma do not exclusively affect either of these arrangements; for in studying them in a specimen that has been macerated for some days, it is found that the majority cross each other in a very evident manner, but that a regain the nerve corresponding to the side from which they came. It is there- fore seen that the nerves of the second pair are composed of one kind of fibres on this side of the chiasma, while beyond it they show two sorts— the fibres from the right and left sides. The majority, we have said, cross each other; and the proof of this is afforded in certain facts observed in ee age anatomy, which are of sufficient interest to be mentioned In the cases so frequently occurring in the Horse, where an eye is lost from the ravages of specific ophthalmia (fluxion périodique), the consecutive atrophy of the optic nerve nearly always stops at the chiasma though it sometimes happens that it gets beyond this; and it is observed that it is usually the nerve opposite to the diseased eye which suffers the most. Otherwise, the arrangement just described is only a degree less advanced than that remarked in certain species—in the osseous fishes for instance—in which the optic nerves entirely cross each other without con- founding or mixing their fibres. Beyond their commissure, the nerves of the second pair are in relation _ with the walls of the optic foramina, then with the posterior rectus muscle (retractor oculi), which envelops each nerve as in a sheath. In the orbits they are also related to some other nerves and vessels. bis z 708 THE NERVES. With regard to its ermination, the optic nerve enters the globe of the eye by pisreleg the sclerotic and choroid coats, towards the most de- — clivitous part o Es; is described in the apparatus of vision as the retina. Before traversing the __ q 4 bottom of the eye, this nerve always becomes markedly constricted. ee The study of the structure of the optic nerve reveals some a facts which it is well to know, though they are more curious in- Remit | teresting. The upper part is entirely destitute of envelope, while the — 7 inferior—that in front of the chiasma—has a double neurilemma. The external layer of this is only a dependency of the dura mater: a kind of fibrous sheath attached at one end to the margin of the optic foramen, and — at the other to the sclerotica. The internal, which is analogous to the neurilemma of the other nerves, emanates from the pia mater, and presents — a multitude of septa (forming the lamina cribrosa), which keep the fibres of this nerve apart from each other. To make this organisation manifest, the latter should be steeped in an alkaline solution for some days, and then washed in a stream of water to remove the softened nervous matter; the nerve is to be afterwards tied at one of its extremities, inflated, tied at the oppositeend, —_ and dried. By means of some sections all the canals that lodge the fascieuli ai. ae of nervous tubules, and which pact are formed by the internal neurilemma, are then shown. = Concerning the properties of — the optic nerve, we will say — nothing ; though they are analo- gous to those of the other nerves of special sense; it is destined to transmit to the encephalon the impressions furnished by the sense of sight, and mechani- cal irritation of it does not cause pain. 3. Third Pair, or Common Oculo- motor Nerves. (Figs. 326, 335.) The nerves of the third pair emanate from the cerebral pe- duncles, near the interpedun- cular fissure, and at an almost equal distance between the corpus albicans and the pons NERVES OF THE EYE, Varolii. Their roots, seven or 1, Ophthalmic branch of the fifth pair; 2, Palpebro- eight in each, penetrate the nasal branch; 3, Lachrymal nerve; 3’, Temporal texture of these peduncles, pass branch of that nerve; 4, Frontal nerve; 5, Ex- backwards, and may be traced ternal oculo-motor nerve; 6, Trochlear nerve; to their nucleus, which Stillin 8, 9, 10, Jat oe Ty of oe Reet beigae 91 2 has placed above the anterior “ nerve; 12, Superior maxillary nerve; 13, rs orbital branches, border of the pons Varolii, and which is united to that of the opposite side by fibres intercrossing on the median line. From the union of these roots results a flattened trunk, which is at first carried outward, and is almost immediately inflected forward to enter, along THE CRANIAL OR ENCEPHALIC NERVES. 709 _ ‘with the sixth pair and the ophthalmic branch of the trigeminal nerve, into the _ smallest of the great suprasphenoidal foramina. 'The common oculo-motor nerve afterwards arrives, by the orbital hiatus, at the bottom of the ocular _ sheath, where it separates into several branches destined to the following _ mouseles of the eye: the elevator of the upper eyelid, superior rectus, _ internal rectus, inferior rectus, posterior rectus—except its internal fasciculus _ —and the small oblique. The branch to the latter is remarkable for its great - Iength ; it reaches its destination in passing to the outside of, and then below _ the inferior rectus. The motor roots of the ophthalmic ganglion furnished _ by this nerve, are given off from the same point as the branch for the small oblique muscle. _ The nerves of the third pair are purely motor, as is shown by their _ ¢onnections with the inferior plane of the cerebral peduncles, and their _ exclusive distribution to contractile organs. They incite all the muscles lodged in the ocular sheath, except the external rectus, the great oblique, and ior rectus. (it also sends a motor filament to the lenticular ganglion, supplies the circular muscular fibres of the iris and ciliary muscle, and presides over _ contraction of the pupil.) ie 4, Fourth Pair, or Pathetici. (Fig. 335, 6.) The pathetic or internal oculo-motor (or trochlearis) nerve is the smallest all the cranial nerves. Its description is extremely simple. It arises the band of Reil, immediately behind the corpora quadrigemina, by | ort roots, which it has been impossible for me to follow very deeply o the substance of the isthmus. ; It is directed outwards, downwards, and forwards, to disengage itself from the deep position it at first occupies, and lies beside the superior branch of the trigemini, accompanying it to the suprasphenoidal foramina, the smallest of which it enters. This opening is exclusively intended for it, and carries it to the bottom of the ocular sheath, when it gains the deep face of the great oblique muscle, in which it ramifies, supplying that organ with the stimulant principle of muscular contractility. ‘The physiological study of this nerve gives rise to some very interesting remarks, which we will sum up here in a few words. The two oblique muscles of the eye pivot the ocular globe in the orbit, without causing the test deviation either upwards, downwards, or otherwise, of the pupillary ss i But this rotatory movement is altogether involuntary, and is only accomplished in certain determinate conditions. “ Guerin, Szokalski, Hueck, and Hélie have remarked, that when the head is alternately inclined to the right or left, while the vision is fixed on any object, the ocular globes describe around their antero-posterior axis an inverse rotatory movement that has the effect of preserving a constant relationship between the object _ from which the luminous rays proceed and the two retine. In this rotatory motion the great oblique muscle of one side has for its congener the small oblique of the other side: thus, when the head is inclined on the tight shoulder, the right eye revolves inwards and downwards on its axis, under the influence of the superior oblique muscle, while the left eye turns on itself outwards and downwards, through the action of the inferior oblique ; when the head is inclined on the left shoulder, an inverse move- ment takes place in the two eyes. This simultaneous rotation of the ocular globes around their antero-posterior diameter, when the head is inclined to ‘. 2? i 710 THE NERVES. one side or the other, is necessary for the unity of perception of visual objects; if one of the two eyes remained fixed while the other turned on its axis, we would perceive two images, a superior corresponding to the healthy — eye, and an inferior to the diseased one. These two images are visi when the head is vertical, and particularly when it is inclined to the affected side; they are confounded into a single one when the head is carried to the healthy side.” ? The involuntary action of the oblique muscles of the eye in this rotatory — movement strongly attracts atttention to the nerves which these muscles receive, and stimulates a desire to learn the particular conditions which permit them to act as excito-motors independently of the will ; although — as well as the muscles to which they are destined, belong to those of ani life. In the present state of science, nothing positive can be affirmed on so delicate a subject. There are, nevertheless, two interesting remarks to make: the pathetic nerve is exclusively destined to the superior oblique muscle, and the long branch sent by the common oculo-motor nerve to the inferior oblique does not.give any filament to the neighbouring parts. This branch is, therefore, also the exclusive nerve of the inferior oblique, and may be considered as a second pathetic. (Sir Charles Bell designated the fourth nerve the “respiratory nerve of the eye,” and asserted that it was large in all animals capable of much expression.) 5. Fifth Pair, or Trigeminii. (Figs. 110, 322, 335, 336, 337, 338, 342.) The nerve we are about to describe has also been named by Chaussier the trifacial nerve. It is distinguished among all the cranial nerves by its enormous volume, the multiplicity of jts branches, the variety of its uses, and its connections with the great sympathetic system. It therefore requires to be described as completely as possible ; and in this description we will include the study of the cephalic ganglia of the great sympathetic system, which ought to be regarded as annexes of the fifth pair. Origin.—The trigeminus belongs to the category of mixed nerves, as it possesses two roots—one sensitive, the other motor. , Sensitive Root (Figs. 337, 338, 7).—This is the largest root. It emanates from the outside of the pons Varolii, near the middle cerebellar peduncle, — and is directed forward and downward to gain the anterior portion of the foramen lacerum, where it terminates in a very great semilunar enlargement constituting the Gasserian ganglion. Flattened from above to below, and — wider in front than behind, this root on the outer side is about 6-10ths of an inch in length, but the inner side is double that measurement because of the oblique position of the ganglion which continues if. If it be traced into the substance of the pons, it will be found that the fibres of the latter separate for its passage from the deep plane it at first oceupies, The following is the manner in which it comports itself in this plane :—This root is separated into two orders of fibres, posterior and anterior. The first pass beneath the arciform fasciculi of the pons Varolii, to be continued with the restiform body, and consequently with the terior columns of the spinal cord; the second separate from each other, and soon become confounded with the cells amassed in the interior of the isthmus, at the anterior cerebellar peduncles,and above the intermediate fasciculus of the medulla oblongata. The fibres of the trigeminus, or the cells 1 Sappey. ‘* Anatomie Descriptive,’ a THE CRANIAL OR ENCEPHALIC NERVES. 711 which receive these fibres, are in communication with several cranial nerves, pp geencnlarly the pneumogastric, glosso-pharyngeal, facial, and auditory. Semilunar or Gasserian ganglion.—This ganglion, which receives the y ‘sensitive root of the trigeminus, is crescent shaped, its concavity being turned backwards and inwards. It may be said to be imbedded in the fibro-cartilaginous substance which in part closes the occipito-spheno- temporal hiatus, and divides it into several particular foramina. Its superior face is covered by the dura mater, and sends a number of filaments to that membrane. The Gasserian ganglion is not continued by a single trunk, but imme- “diately gives rise to two thick branches, one of which leaves the cranium _ by the foramen ovale—an opening formed by the above-named hiatus; while the other is lodged in the external fissure in the intercranial face of the sphenoid bone, and passing along it as far as the entrance to the supra- _ sphenoidal foramina, bifurcates. Hence it results that the trigeminus is divided, even at its origin, into three branches: two superior—the ophthalmic branch of Willis, and the su maxillary nerve, commencing by the same trunk; and an inferior, which constitutes the inferior maxillary nerve. Motor or small root (Figs. 337, 338) —This is a flattened band which emerges from the pons Varolii, at the inner side of the principal root. Its 4 _ fibres may be easily followed to the interior of the pons Varolii, and in their direction they comport themselves like those of the large root, by becoming confounded with the substance of the antero-lateral fasciculus of the medulla oblongata. Leaving the pons, this root passes forwards on the inferior face of the Gasserian ganglion, which it crosses in a diagonal manner outwards, and beyond which it intimately unites with the fibres _ of the inferior maxillary nerve. The superior maxillary nerve and the ophthalmic branch do not receive any fibres from it. In the fifth pair, then, it is only the inferior maxillary nerves which are at the same time sensitive rand motor, and are rea] mixed nerves. A. Opuruatmic Branon (Fig. 335, 1)—This is the smallest of the three divisions furnished by the Gasserian ganglion, and proceeds by a trunk common to it and the maxillary nerve, which will be described here- after. This branch enters the smallest of the large suprasphenoidal foramina, along with the common and external oculo-motor nerves, and in the interior of this bony canal divides into three ramuscules, which reach the bottom of the ocular sheath by the orbital hiatus, These ramuscules are : 1. The frontal or supra-orbital (supratrochlear) nerve. 2. The lachrymal nerve. 8. The nasal or palpebro-nasal nerve. 1. Frowran Nerve (Fig. 335, 4).—This is a flat, voluminous branch placed on the inner wall of the ocular sheath, and proceeding nearly parallel with the great oblique muscle of the eye to the supra-orbital foramen, into which it passes along with the artery of the same name. Undivided before its entrance into this orifice, immediately after its exit from it, it separates into several ramuscules, which meet the anterior auricular nerve, and are expended in the skin of the forehead and upper eyelid. 2. Lacnryman Nerve (Fig. 335, 3).—This is composed of covennl filaments, which ascend between the ocular sheath and the elevator muscles of the eyelid and superior rectus, to enter the Jachrymal gland. One of 712 THE NERVES. these (Fig. 335, 3') traverses the ocular sheath behind the orbital and places itself, from before to behind, on the external surface of the matic process, where it divides into a number’ of ramuscules, some of w. mix with those of the anterior auricular nerve to form the plexus of that name, while the others pass directly into the anterior muscles and pep ments of the ear. , Patrrpro-nasaL Nerve (Fig. 335, 2).—This describes a curve, like the ophthalmic artery, and passes with that vessel into the cranium by the — : orbital foramen. After coursing through the ethmoidal fissure that lodges the artery, it traverses the cribriform plate, and divides into two filaments—an __ internal and external, which ramify in the pituitary membrane on both sides of the nasal fossa. Before entering the orbital foramen, this nerve gives — off a long branch (infratrochlear) that glides over the floor of the orbit to A reach the nasal angle of the eye, where it is distributed to the apparatus lodged there, as well as to the lower eyelid; it also detaches a P long filament to the membrana nictitans and the sensitive roots of the ophthalmic ganglion, which will be noticed hereafter. B. Superior Maximuary Nerve (Fig. 336, 15).—This nerve is” ‘the real continuation of the superior trunk given off by e Gasserian ganglion, where we will begin to follow it to its termination, examining bri the ophthalmic branch already described as a collateral division of this trunk. Remarkable for its volume, and its prismatic and funicular shape, the superior maxillary nerve proceeds from the inner and upper section of the semilunar ganglion, and at first occupies the fissure on the internal face of the sphenoid bone, without the cavernous sinus, and is covered at this point by the dura mater. After sending the ophthalmic branch into the smallest of the great suprasphenoidal conduits—the great sphenoidal fissure, it enters the most spacious of these openings—the foramen rotundum, arrives in the orbital hiatus beneath the sheath of the eye, and, with the internal maxillary artery, passes along the space filled with fat which separates that hiatus from the origin of the supramaxillo-dental (infra-orbital) canal, which it follows to its external orifice on the face. There it terminates in a number of branches named the infra-orbital ramuscules (or pes anserinus, from their resemblance to the claws of a goose’s foot). In its course, this nerve gives off a large number of collateral divisions, among which may be more particularly distinguished : 1, An orbital branch. 2. The great or anterior palatine nerve. 3. The staphylin or posterior palatine nerve, 4. The nasal or spheno-palatine nerve. 5. The dental nerves. In addition to which are described : 6. The infra-orbital, or terminal branches of the superior maxillary nerve. 1, OrsiraL Branon (Fig. 335, 13).—This ramuscule arises in the inte- — . rior of the suprasphenoidal canal, and enters the ocular sheath with the divisions of the ophthalmic branch. It almost immediately breaks up into two or three very slender filaments, which ascend to the temporal angle of the eye, passing between the fibrous lining of the orbit and the outer surface of the motor muscles of the eye, and are distributed to the eyelids and neighbouring integuments. 2. Great or Awnrertor Patatine Nerve (Fig. 148, 3).—It arises “ae i | | t a 7 7 4 : Le Db: #y ( fe + Bh Bys J s Ee eee = CA vee THE CRANIAL OR ENCEPHALIC NERVES. 713 _ from the superior maxillary nerve at the orbital hiatus, from a trank common » and the nasal and staphylin branches ; it passes into the palatine canal __ with the palato-labial artery, which it follows to the foramen incisivum, _- During its course in the palatine canal, this nerve throws off two or three ;. = oo which escape by particular foramina to the anterior part of 1¢ soft palate—median palatine nerve. Frequently they arise from a common paey before the great palatine nerve enters its canal, and pass to their emenination by particular openings. For the remainder of its extent on the f of the palate, this nerve forms, around the artery it accompanies, a ? exiform network similar to that of the ganglionic nerves; the filaments ping laterally from it are sent to the soft parts of the palate, as well as ___ 8. Srapnytin or Posrenion Panarins Nerve (Fig. 148, 8).—The filaments composing this nerve are very easily separated, and frequently _ anastomose with those of the preceding nerve. They accompany the ; i meal artery in the canal of that name, bend in front of the pterygoid _ process to penetrate the soft palate between the glandular layer and the tunica albuginea. They then become inflected backwards, and ramify either in the mucous -_ a — of the velum pendulum, or the : and circumflexus-palati muscles. This destination, = in this nerve the presence of motor fibres ; we will see _ hereafter whence they come. bs 4. Nasat orn SpuHeno-patatine Nerve.—Springing from the same _ trunk as the two preceding nerves, thicker than the staphylin, and nearly of _ the same volume as the anterior palatine, the nasal nerve passes with its artery into the nasal or spheno-palatine foramen, to penetrate the cavity of the nose, where it separates into two branches—external and — _ which are distributed to the pituitary membrane. 5. Denrat Brancues.—These are destined to the roots of the upper _ teeth, and proceed from the superior maxillary nerve during its inter- _ maxillary course; some even arise before the entrance of that nerve into the bony conduit, which it passes through to reach the face. These latter, us to the posterior dental nerve of Man, enter the canal with the _ parent branch, and throw their divisions into the roots of the last molar tooth, and sometimes also into the second last. One portion of them plunges directly into the maxillary protuberance, to be expended in the mucous membrane lining that protuberance, after furnishing some fila- _ ments to the periosteum. Among the dental branches given off from the maxillary nerve during * _ its interosseous course, some-pass to the molars, and others to the canine and - ineisor teeth. The first, or middle dental nerves, separate in groups from _ the maxillary trunk on its passage above the roots of the grinding-teeth ; _ they penetrate these roots after a brief forward course, and give some thin filaments to the membrane lining the maxillary sinuses. J The second are only at first a single branch—the anterior dental nerve, which rises from the maxillary trunk shortly before it leaves its bony canal. _ After a somewhat long track in the substance of the maxillary bones, this branch becomes expended in furnishing the ramuscules for the canine tooth and the incisors ; it is always accompanied by a very slender arterial twig. %. Inrra-orsitaAL on TerminaL Brancues or tae Superior Maxit- tary Nerve.—These ramuscules spread on the side of the face in a magni- i 714 THE NERVES. ficent expansion, which may be looked upon as one of the richest nervous apparatus in the animal economy. Covered at its emergence from the infra- orbital foramen by the supermaxillo-labialis muscle, this fasciculus descends beneath the supernasalis-labialis and pyramidal muscle of the nose (super- maxillo-nasalis magnus) towards the nostrils and upper lip, which receive the terminal extremities of its constituent branches in the substance of their muscular and tegumentary tissues ; these branches are slightly divergent and — flexuous, and for the most part anastomose with a large motor trunk furnished — by the facial nerve (Figs. 836, 15’). ; C. Inrerion Maxitiary Nerve (Figs. 336, 11; 110, 12).—At its exit from Fig, 336, GENERAL VIEW OF THE SUPERIOR AND INFERIOR MAXILLARY NERVES. The eye has been excised, after sawing through and removing the orbital and zygomatic processes. The maxillary sinuses have been exposed by means of a gouge or chisel, the masseter muscle removed, and the inferior maxilla opened to show the nerve in its interosseous course. Facial nerve ; 2, Origin of the posterior auricular nerve; 3, Filament distributed to the stylo-hyoid muscle; 4, Digastric branch ; 5, Trunk of the anterior auricular nerve; 6, Origin of the cervical filament; 7, Plexus formed by the union of the facial and superficial temporal nerve; 7’, Branch of that plexus united to the infra-orbital nerves, 15’; 11, /nferior muvillary nerve; 8, Superficial temporal nerve; 9, Masseteric nerve; 10, Gustatory nerve; 12, 12, Dental branches; 13, Mylo-hyoid nerve; 14, Buccal nerve; 15, Superior maxillary nerve; 16, Spheno- palatine ganglion; 17, Staphylin (or palatine) nerve; 18, Common carotid artery; 19, Trunk of the occipital; 20, Trunk of the internal carotid; 21, External carotid; 22, Trunk of the posterior auricular artery embraced by a loop of the facial ; 23, Trunk of the superficial temporal; 24, Internal maxillary artery ; 25, Trunk of the deep anterior temporal artery; 26, Orbital branch of the superior dental; 27, Buccal artery ; 28, Inferior dental artery. — ~~ the cranium, this branch is situated immediately within the temporo- maxillary articulation, and from thence is directed forward and downward, passing at first between the two pterygoid muscles, then between the inner and deep face of the maxilla, arriving at the maxillo-dental foramen, through which it passes and runs along the whole course of the canal, escaping at last by the mental foramen to form an expansion of terminal branches THE CRANIAL OR ENCEPHALIC NERVES. 715 similar to those of the superior maxillary nerve, and named the menta! nerves. _ For the first third of its extent, the inferior maxillary nerve is a flattened band ; but beyond this it becomes thicker, and acquires a funicular shape. At its: origin it gives rise to four branches : 1. The masseteric nerve. 2. The buccal nerve. 3. The nerve of the internal pterygoid muscle. _ 4, The superficial temporal or subzygomatic nerve. After its emergence from between the two pterygoid cama it furnishes : 5. The gustatory nerve. 6. The mylo-hyoid nerve. Tn its intermaxillary course, it detaches : 7. The dental branches. Also a triple series of collateral nerves which we will study before describing the terminal branches ; these are : 8. The mental nerves. The trunk of the inferior division of the fifth pair represents a mixed nerve, because it is formed of sensitive and motor fibres. Is it the same for each of the branches just enumerated ; that is, do they all contain fibres of _ the two orders? This is a question on which the dissection of the two roots has taught us very little, for their fibres soon become confounded so intimately that it has always been found impossible to follow them separately eit dail netic. But the study of the distribution of these branches, corrobo- rated oaetiag oe epaee experiments, has greatly enlightened us in this e see among them nerves destined to the muscles, and others et ie -glendules or integumental structures; the first are therefore chiefly ” of motor fibres, like all other muscular nerves; and the second exclusively contain sensitive fibres, or at least are deprived of voluntary motor fibres. In describing each branch in particular we will notice ~— special properties. 1. Masserenic Nerve (Figs. 336, 9; 342, 2).—-It is detached from the prin- cipal ‘trunk, i in front, though close to, ‘the base of the cranium, bends round the anterior face of the temporo-maxillary articulation, and passes through the sigmoid notch of the inferior maxilla to descend into the texture of the masseter muscle and there ramify. At its origin, this nerve furnishes two filaments which often proceed from one very short trunk, and ascend into and expend themselves in the tem muscle; this trunk is then the deep posterior temporal nerve. ore crossing the corono-condyloid notch, it detaches to this same temporal muscle a small branch which represents the deep middle temporal nerve. The destination of all these branches sufficiently proves that they are motor. 2. Buooat Nerve (Figs. 336, 14; 342, 4).—This nerve, which is twice the size of the preceding, arises from the same point, though slightly below it. It is directed forwards, traverses the external pterygoid muscle, and reaches the ior extremity of the superior great molur gland; leaving which, it is beneath the buccal mucous membrane, and descends to the commissure of the lips, along the inferior molar gland and the inferior border of the alveolo-labialis muscle. 716 THE NERVES. It gives some very fine filaments to the external pterygoid, in ite p across that muscle. Beyond this, it furnishes a very slender ramuse the orbital portion of the temporal muscle—the analogue of the ee temporal of Man. oh On the superior molar gland, it emits a fasciculus of branches to organ and the alveolo-labialis muscle. In its submucous track it off, at certain distances, ramuscules of various sizes which 10. inferior molar gland and the buccal membrane ; while its termi are expended in the lining membrane and glands of the ling, 3 near commissure. The majority of the filaments given off by this nerve to the exter pterygoid and temporal muscles are doubtless motor, but the other ram cules are sensitive; even those distributed to the alveolo-labialis muscle are no exception, for its submasseteric portion is supplied by the 1 facial, a8 well as the superficial or anterior part. 3. IvrernaL Prervcom Nerve.—lIt forms, with the p a single fasciculus, which leaves the anterior part of the inferior maxil! nerve. After crossing, outwardly, the internal maxillary artery, it descen between the nervous trunk from which it emanated, and the emi of the tensor palati muscle, to go to the inner side of, and become exp in, the internal pterygoid muscle. This nerve is the smallest branch of the inferior maxillary trunk, after the mylo-hyoid, and excites the contraction of the muscle receiving it. 4, SuperricraL Temporat or Suszycomatic Nurve (Figs. 336, 8; 342, 8). —This arises from the inferior maxillary nerve, at the opposite side of the a fasciculus formed by the three preceding branches, or posteriorly. Placed at first at the inner side of the temporo-maxillary articulation, and between it — and the guttural pouch, it is afterwards directed downwards and curwanig il passes between the parotid gland and the posterior border of the inferior — maxilla, and below the condyle; it then bends round the neck of that bony” eminence to arrive beneath, and to the outside of, the precited arcioulerens a where it terminates by anastomosing with the facial nerve, x In its course it sends off numerous fine filaments to the guttural pouch, the parotid gland, and the integuments of the temporal region. Among the latter, it is necessary to notice more particularly those which scooeeingas Sa the superficial temporal artery. " The superficial temporal nerve appears to be esolusiely ocascaaeae Section of it, before it anastomoses with the facial nerve, does not really — 4 prevent contraction of the muscles which receive the divisions of the plexus — formed by this anastomosis. Ss 5. Gustatory Nerve! (Figs. 111, 17; 336, 10; 342,5).—The gustatory — nerve, the principal branch of the inferior maxillary trunk, which it almost equals in volume, is detached at an acute angle from the anterior border of that — nerve shortly after its exit from the pterygoid muscles. To scoot” its course, which it effects in describing a slight curve whose concavity is antero- — posterior, it is directed forwards and downwards, passing between the internal pterygoid muscle and the branch of the inferior maxillary bone, and gaining the base of the tongue, where it is situated beneath ¢ the buccal mucous membrane. It afterwards descends more deeply, betw the mylo-hyoid and hyo-glossus longus muscles, turns round the infer rio 1 (Professor Chauveau designates this the lingual, or small hypoglossal nerve. To prevent confusion I have, in preference, retained the usual desiguation given to it it im country.) Pe Me me r =i = is 7 = t THE CRANIAL OR ENCEPHALIC NERVES. 717 border of the latter—including also Wharton’s duct, to enter the inter- tice agen the genio-glossus from the hyo-glossus longus and brevis m this point it continues to near the free extremity of the eer Deccsccccding in a very flexuous manner, and giving off, on its course, ; ons equally tortuous and which traverse the organ, but without detaching any ramuscules to the lingual muscles; these divisions terminate in the middle and anterior portions of the lingual mucous membrane. Before penetrating the mass of the tongue, this nerve furnishes: 1, At, Ena in front of, the posterior pillars of that organ, some small ramuscules which are sometimes: plexiform, and are distributed to the mucous membrane at the base of the tongue; 2, Lower, and behind, one or two thin filaments which are carried to Wharton’s duct, and ascend with it _ to the maxillary gland; 3, A sublingual branch, whose divisions enter the P — of that name, as well as the mucous membrane covering the sides of e. The gustatory nerve receives, near its origin, the tympano-linqual filament or chorda tympani—a branch of the facial nerve soon to be described. Its terminal divisions mix and anastomose with those of the great hypoglossal nerve, in the deep muscular interstice which lodges both. . Physiology teaches us that the gustatory nerve gives to the anterior _ two-thirds of the lingual mucous membrane ordinary sensation, and, in _ addition, that special sensibility (or gustatory power) by virtue of which _ that membrane enjoys the property of appreciating savours. This is its exclusive function. With regard to the tympanic filament from the facial: _ nerve, and which is joined to the gustatory, M. Bernard is of opinion that it participates in the exercise of this sense of taste. Its radiating fibres extend _ to the submucous muscular layer of which we have spoken, and on which the lingual papille rest, and endow it with the property of acting on these _ papille by adapting them, we may say, to the sapid substances brought into contact with them. lLussana goes further than this, and, basing his state- - ment on observations made on Man and on experiments, asserts that the nerve of the tympanum passes to the mucous membrane, and endows it with the sense of taste. Vulpian, however, does not agree to either of these opinions, because, according to his experience, this nerve does not go to the but stops at the submaxillary ganglion. _ 6. Myto-nyor Nerve (Fig. 336, 13).—The designation of this nerve indicates its destination an It goes to the muscle bearing its name, and excites its contractility; it arises opposite to the preceding, and, like it, descends between the internal pterygoid muscle and the inferior max- overt bone, adhering somewhat closely to the latter. But arriving at the ior border of the mylo-hyoideus, it passes to the outside of it, and mheoting with the sublingual artery, ramifies on the external face of that 7. Denrat Branours (Fig. 336, 12).—These are of two orders: some ‘ ing to the molar, the others to the canine and incisor teeth. Their Reiseine does not merit any special indication. 8. Mestat Nerves, or Terminat Brancues or tae Inrerton MaxtLiuary Nerve.— Perfectly analogous to the infra-orbital ramuscules, these nerves form a fasciculus by diverging and flexuous branches, which leave the mental foramen to be distributed to the textures of the lower lip, after receiving a branch from the facial nerve (Fig. 336, 11’). ‘Pare Symparuerio GANGLIA ANNEXED TO THE Firte Parr.—These ganglia, joined by filaments of communication to the anterior extremity “ THE NERVES. i Latape sy * es of the great sympathetic nerve, in reality belong to the formed by that nervous chain, as they possess the formation of the other ganglia composing it. It is therefore necessary that have a motive sufficiently powerful to induce us to move them from natural category, and mix up their description with a nerve so different tc them in its nature and functions. This motive we find in the i relations of contiguity and continuity which these ganglia manifest tow the branches of the trigemini ; in the fact that we sometimes find them united to these branches, and deeply mixed up with their fibres ; and also : in certain cases, they seem to disappear entirely, and then their filaments — of emission or reception are directly received or emitted by the fifth pair. The study we are about to undertake of each of the ganglia will justify what we have advanced. We will precede it by a few words introduction as to the general facts relating to these small o The number of sympathetic ganglia annexed to the fifth pair ie tible of variation, not only in different species, but also with i indi of the same species. - In the domesticated mammifers, we somewhat constantly, though nottn- variably, find three principal, placed on the course of the branches ema- : nating from the Gasserian ganglion. Theseare: 1, The ophthalmic ganglion, belonging to the nerve of the same name; 2, The spheno-palatine annexed to the superior maxillary branch ; 3, The otic ganglion, which lies — beside the inferior maxillary nerve. Anatomists describe other two, the — submaxillary ganglion and the naso-palatine (or Cloquet’s) ganglion ; but | their presence is not always constant in Solipeds, and their existence in the — other domesticated animals is at least problematical. “Ag These small bodies possess those common characters which have been — so clearly indicated by Longet, and to which we will briefly refer. All are in communication with the superior cervical ganglion by one or more — generally very slender filaments, and all receive one or more ramuscules — from a sensitive and a motor nerve: these ramuscules—the afferent branches — of the ganglia—are considered as their roots. All, finally, emit from their periphery a more or less considerable number of emergent branches or cations which share the properties, more or less modified, of the two orders of roots. The description of each ganglion therefore includes, indepen- dently of its form, situation, etc., an indication of all these ramuscules: ramuscules of communication with the superior cervical ganglion; afferent ramuscules or roots ; and emergent ramuscules, This rule can be applied to all the ganglia, and ‘renders their study perfectly methodical. 1. Ornrnatmio (Omiary or Lenticunar) Ganetion.—This ganglion is readily discovered, as it is always in contact with the common oculo-— motor nerve, and united to it near the point where the branch passing to the inferior oblique muscle arises. It rarely exceeds the volume of a grain of millet, and is sometimes so minute that it would altogether escape ob- servation, did we not know exactly where to look for it. a Its motor root is generally formed of two very short ramuscules co: from the third pair. Its sensitive root, much longer, proceeds from rot palpebro-nasal nerve; it is usually through the medium of this root that the ophthalmic ganglion communicates with the superior cervical ganglion, : by means of a thin filament it receives from the cavernous plexus. The emergent filaments leave the anterior part of the ganglion, ond arrange themselves in a flexuous manner around the optic nerve to reach the selerotica, bearing the name of ciliary nerves. Some emanate directly nee i Hite = tee ah be as THE CRANIAL OR ENCEPHALIC NERVES. 719 from the palpebro-nasal nerve, especially when the ganglion is rudimentary. Their number is uncertain, though it is usually from 5 to 8. - Reaching the sclerotica at the bottom of the eye, they traverse that membrane, and pass between its inner surface and choroid coat to the ciliary circle (or ligament), where each divides into two or three ra- muscules that anastomose with those of the adjacent ciliary nerves, and in this manner form a circular plexus. From the concavity of this nervous circle arises a series of plexuous divisions, which are spread over the iris, whose contractile property is submitted to their influence. 2. Spueno-patatine, on Mecket’s Ganarion.— The largest of the cephalic ganglia, nothing is more variable than the disposition of this small body. The following appears to be the most constant: in raising the superior maxillary nerve in its course across the space separating the _ orbital from the maxillary hiatus, we discover, lying on the upper border of the spheno-palatine nerve, a long, grey-coloured enlargement; this constitutes the ganglion we are about to describe. lt is elongated and slender, irregularly fusiform, constricted at different points of its extent and dilated in others ; it is not attached to the spheno- _ palatine nerve by simple cellular adhesions or by some branches thrown from one cord to the other, but is intimately united to it by means of a most complicated intercrossing of fibres, in such a way that the spheno- palatine ganglion really forms part of the nerve of that name. Afferent branches.—It receives, posteriorly, the Vidian nerve, a com- posite ramuscule which constitutes its motor root, and connects it with the superior cervical ganglion. This nerve will be described with the facial, as that trunk furnishes its principal portion. Its sensitive roots naturally come from the spheno-palatine nerve; they are as remarkable for their - number as their volume, and also enter the posterior part of the ganglion. Emergent branches.—F our series of these are recognised: 1. A very numerous series which is detached at a right angle from the superior border of the ganglion, and proceeds towards the ocular sheath. _ The majority appear to be lost in that fibrous membrane, but we have seen some pass through it, creep on the lower and inner wall of the orbit, and arrive at the margin of the orbital foramen. There they were manifestly united to the other filaments coming from the palpebro-nasal nerve, and formed a small plexus whose divisions seemed destined to the ophthalmic vessels, and even to some of the muscles of the eye, more especially the _ oblique ones. Among these divisions we have observed some which went to join the nerve of the membrana nictitans. 2. A second series proceeding from the opposite border, and establishing a union between the ganglion and the spheno-palatine nerve, or passing to the _ palatine nerves in a more or less complicated plexiform manner, to reinforce them. 3. A group arising from the anterior extremity and immediately passing to the spheno-palatine nerve. mh. 4 74 last fasciculus detached from the posterior extremity to enter the two sey suprasphenoidal canals. ch is the most usual arrangement of the spheno-palatine ganglion. We have found it divided into three small masses connected with each other by numerous filaments of a deep grey colour, and free from all ad- herences with the spheno-palatine nerve. The small posterior mass in this case received the Vidian nerve and the sensitive roots from the fifth pair. The distribution of the emergent branches was unaltered. 720 THE NERVES. Among the anatomo-physiological facts ining to the study of t ganglion, we may remark that the staphylin, or posterior palatine, n derives from it the motor property which permits it to excite the ¢ traction of the muscles in the soft palate. dg 3. Orc (on Arnoxy’s) Ganation.—It appears to us that the 7 of this ganglion is not constant, for we have sometimes found it replaced by a small plexus provided with some almost microscopic ganglionic granulations. 9 When it does exist, it presents itself as a small fusiform enlargen placed within the origin of the inferior maxillary nerve, beneath the i tion of the Eustachian tube. ‘To discover it, we have only to look for’ commencement of the buccal nerve, to which it is joined by some filame which are so short and thick, that we might imagine it to be fixed on trunk. i Its sensitive roots are represented by the preceding filaments. The eal a superficial petrous nerve, coming from the facial, constitutes its a 00 From the sympathetic ramuscule accompanying the internal wi ge artery, it. receives its filament of communication with the eupedial €) ganglion. Among its emergent ramuscules must be cited a superior filament, aaa enters the petrous portion of the temporal bone to disappear in the internal muscle of the. malleus (tensor tympani), and two inferior filaments of a more considerable volume which separate in numerous ramuscules destined a to the pterygoid muscles, the Eustachian tube, and the tensor paleti muscle. PuystotoaicaL Resumé or tHe Firrn Patr.—The trigemini es sensation to the skin covering the head, into the eyelids, the: soft i omy a palate, the nasal fosse and sinuses, the nostrils, the greater portion of the tongue, and into the salivary glands and cheeks, and the upper and lower lips. Bi The enormous tuft formed by the terminal branches of the superior maxillary nerve, endow the upper lip with the attributes of an rr f very Zs exquisite tact. oie 9 The gustatory branch is, for the anterior two-thirds of the essential instrument of the sense of taste. rot By its motor root, the inferior maxillary nerve provokes dhidie contraction of the muscles that bring the jaws into apposition—all those compo masseteric region, except the digastricus. This root is often d consequence of its function, the masticatory nerve. The fifth pair also influences, as is demonstrated by vivisections salt oad 43 observation of pathological facts, the secretion of the mucous membranes — and glands receiving its filaments : undoubtedly by a reflex action which — q proceeds from the isthmus, and perhaps from the Gasserian ganglion. . Finally, it is admitted that the nutrition of the tissues in which the | trigeminus ramifies depends upon that nerve. But here there is an ~e ration; for if nutrition be modified in these tissues, consequent on the section of the fifth pair, this effect is certainly due to paralysis of the capillaries, whose contractility is probably excited by the organic fibres mixed with the sensitive filaments of the fifth pair. ~ The ramuscules sent by the sympathetic chain to the Gasserian a are perhaps not foreign to the part the fifth pair seems to play in the — secretory and nutritive functions. 7 2 |THE CRANIAL OR ENCEPHALIC NERVES. 721 6. Sixth Pair (Abducentes), or External Oculo-motor Nerves. (Fig. 385, 5.) The external oculo-motor originates from the medulla oblongata, imme- diately behind the pons Varolii, by from five to eight converging roots, which appear to issue from between the inferior corpus pyramidale and the lateral fasciculus of the medulla (Figs. 837, 338, h). It is directed immediately forward, leaves the pons Varolii in lying close to the inner side of the superior maxillary nerve, and traverses the sphe- noidal canal, which already lodges the ophthalmic branch of the fifth pair ' the common oculo-motor nerve, to pierce the bottom of the orbit. It is entirely expended in the external rectus (or abductor) muscle of the eye, after giving off a small ramuscule to the external portion of the posterior rectus. 7. Seventh Pair, or Facial Nerves, (Figs. 110, 336, 337, 338.) The facial (portio dura) is a nerve exclusively motor at its orgin, but Fe becomes mixed, during its course, by the addition of several sensitive ches. ’ Origin.—It emanates from the medulla oblongata, immediately behind the pons Varolii, and appears to originate at the external extremity of the _ transverse band that margins the posterior border of that protuberance. But if we attempt to trace its origin in the substance of the medulla oblongata, we see the single fasciculus it constitutes, at its point of emergence, descend into the groove of separation between the pons Varolii and the above-mentioned band ; it then traverses nearly the whole thickness of the medulla, passing between the lateral cord or column, and that portion of the restiform body which is continuous with the large root of the fifth pair. Arrived near the bottom of the fourth ventricle, the facial nerve separates into several roots—some ; anterior, others posterior—which are soon lost in the cells forming the corresponding nucleus. Among these fibres are some which remain isolated from the preceding, and, ing the median line, enter the Raat castens of the opposite side (Fig. 337 eee Bearecly has_ the facial nerve left the roma kf oblongata, before it is direc SECTION MADE THROUGH THE sU : outwards, to pass into the internal = ywepuera rtaeaien: Geleuad te eM dong auditory meatus, along with the oniGINs oF THE FIFTH AND SIXTH NERVES, ; nerve, which lies in con- AND PORTIO DURA OF THE SEVENTH, tact with it behind. It afterwards _ enters the aqueduct of Fallopius, courses along it, and follows its inflexions, which results in its forming a bend forward at a short distance from the internal opening of the canal, and a curve whose concavity is anterior, on its e behind the cavity of the tympanum. On leaving the aqueductus ii by the stylo-mastoid foramen, it is hidden beneath the deep face _ of the parotid gland, and continues to be inflected forward, passing between that gland and the guttural pouch, and reaches the posterior border of the inferior maxilla, where it issues from beneath the anterior margin of the parotid to become superficial, and. place itself on the = muscle, A 299 THE NERVES. © immediately beneath the temporo-maxillary articulation. There it tox | minates in two or three branches, which anastomose with those of the super- ficial temporal nerve from the fifth pair, thus forming the sulbzygomatic plecus (pes anserinus, Fig. 110), or Distribution.—a. In its interosseous course, the facial nerve success’ a y furnishes : ? 1, The great superficial petrous nerve (nervus petrosus superficialis aie m4 2. The small superficial petrous nerve (nervus petrosus superficialis manors S| 83. The filament of the stapedius muscle (tympanic branch). Piet a 4, The chorda tympani. * igh It communicates, besides, with the pneumogastrie nerve, by means of es voluminous filament described as : 5. The anastomotic branch of the pneumogastric. a ; b. The branches it emits on its course beneath the parotid glani arise either from its superior or inferior border ; they are: 4 6. The occipito-styloid nerve. ‘ ; 7. The stylo-hyoid nerve. . " 8. The digastric nerve. ie ch 9. The cervical ramuscule. 10. Filaments to the guttural pouch and parotid gland. The superior branches comprise : 11. The posterior auricular nerve. 12. The middle auricular nerve. 13. The anterior auricular nerve. ! c. To this collection of collateral ramuscules are added the wide branches, formed by their anastomoses with the superficial temporal nerve : 14, The subzygomatic plexus. A. Contaverat Brancues.—1. Great Sorerrrcran Perrovs Nexve.—_ This is a very remarkable ramuscule, which is detached from the bend of the facial nerve to proceed to Meckel’s ganglion. The importance of the peculiarities attaching to the study of this nerve requires us to call attention to its origin, course, and termination; though the details into which we are about to enter may be omitted by the student. Origin.—Ganglion geniculare-—The manner in which the great supers _ ficial petrous nerve comports itself at its origin is yet an obseure and — controverted fact, on which however light is beginning to be thrown. The — following is the most general opinion: This nerve arises from a small grey — enlargement, the genicular ganglion (or intumescentia gangliformis), placed on the course of the facial nerve, at the summit of the angle which that nervous trunk describes after its entrance into the aqueduct of Fallopius ; and the presence of this small ganglion on the seventh pair should assimilate the facial to a mixed nerve, whose sensitive root would be represented by the portio intermedia of Wrisberg—a thin filament comprised between the and eighth pair, and which emanates directly from the medulla oblongata’ to pass into the posterior part of the ganglion geniculare. We have constantly found this ganglion in the domesticated animals, There exists, in fact, on this angle or elbow of the facial nerve, a very grey, conical prominence, composed of ganglionic corpuscles which a micro- scopical examination readily reveals, and giving origin on its apex to the great superficial petrous nerve. This prominence, which, we repeat, is very ee THE CRANIAL, OR ENCEPHALIC NERVES. 723 ' L, forms part of the facial nerve, on which it only presents a kind of Li Eo cence. We have never seen the sharp and precise limitation of its bs yn at is figured in the majority of iconographies of human anatomy. a the other hand, when, on portions steeped for several weeks in water ted by nitric acid, we have studied the constitution of the great S nerve, even at its origin, we have found it formed of two fasciculi sily separated—one internal, the other external: the latter alone is itinuous with the geniculated ganglion ; the other traverses the facial rv pio before to behind, then it is suddenly inflected inwards to ascend to origin of the nerve, and mix with its fibres ; but this fasciculus very often nt ins its independence to the medulla oblongata, into which its fibres strate separately ; they then appear as a small particular trunk beside t of the principal nerve, and comprised between it and the auditory. a petrous nerve does not, therefore, proceed exclusively from the gang ion geniculare, as considerable portions of its fibres, entirely destitute of nglionic corpuscles, emerge directly from the facial nerve. With ard to the external fasciculus, the sepatation of its fibres by the action of t et shows very plainly that the grey substance of the ganglion is found t exclusively on their track; and if we trace these fibres, like those of he preceding fasciculus, into the substance of the facial nerve, we will find instead of proceeding towards its origin, they appear to be directed iD ite termination: a remarkable circumstance, which we believe may be ex plained by admitting that they come from the anastomosing branch of the meumogastric nerve, of which we will speak hereafter. _ a this arrangement, it results that the great petrous nerve arises from the facial by two real, though intimately connected, roots : the internal is evidently motor; the internal possesses the ganglionic corpuscles of a ‘cama five rot ; and the trunk they both form may be regarded asa mixed As will be observed, our view of the ganglion geniculare differs from opinion with regard to it, inasmuch as we make it belong } usively to the great petrous nerve, and not to the whole of the facial fasciculi. On the other hand, the portio intermedia of Wrisberg is not, in our ‘opinion, the sensitive root of the facial, whose fibres we only look upon as me aes it is not even that of the great superficial petrous nerve, of which it “ , at the most be considered as only an accessory filament. In the Horse, iis Faruneonle is extremely attenuated, and can scarcely, if at all, be dis- guished at its origin from the filaments of the lateral root of the auditory ve; it is seen to enter the aqueduct of Fallopius, and divide on the bend geoghiform enlargement) of the facial nerve into several gradually linishing filaments, which are confounded with the proper fibres of this ‘ = or the ganglion geniculare. a difference there is between this arrangement and that of the 2 sensitive roots opposite the ganglia placed on their track! Why sita fe to admit that this nerve of Wrisberg is on'y an anastomosing twig ng from the auditory nerve to the facial? Is it because of the radical 2 in the properties of the two nerves? Nature, in bringing them so Slimtother, does not appear to have taken into account this difference ; Tee reason for this anastomosis might be explained by the cennections the seventh pair maintains with the active portions of the auditory apparatus. Is it not the facial nerve that animates the stapedius muscle, and, in an ndiree manner, that of the malleus? Are all the muscles of the external ear "not under its influence? In the present state of science it de he Snes A 724 THE NERVES, to discover the functional relationship that may exist between the cor nections of the ear with the facial, and those of the latter nerve with — auditory: but the mind perceives this relationship, and that ought to suffice. _ The opinion which regards the nerve of Wrisberg as the sensitive root r of the facial has, we believe, been more particulary accredited by the a - rent impossibility of otherwise accounting for the sensibility this possesses, even at its exit from the stylo-mastoid foramén—that is, ire contracting any anastomosis with the fifth pair; but this sensibility exclusively to the fibres of the communicating branch sent by the pneumo- gastric nerve, and not to the fasciculi of the facial, as is proved by stirs lating the latter outside the aqueduct of Fallopius, after destroying the — pneumogastric at its origin. If it is sought to regard the i Fe nerve absolutely as a branch distinct from the original filaments of the auditory, and if it be determined to make it a sensitive nerve, then it must — at least be admitted that it does not carry its sensibility beyond the stylo-— 4 mastoid foramen, and that all its filaments disappear in the ramuscules- é furnished by the facial in its interosseous course. Otherwise, it is rat 4 that M. Longet considers this nerve as forming the small superficial pe 4 branch and the nervous filament of the stapedius muscle; but he motor branch destined to supply the muscles of the middle ear. His idea pe very ingenious, and would assuredly be feasible if it were possible to follow the intermediate nerve from its origin to the lateral column of the medulla — oblongata ; but, unfortunately, this is not the case, as the small ramuseule — only appears to be an offshoot of the fibres proper to the auditory nerve. To sum up, the great superficial petrous nerve proceeds from the facial — by two roots: one motor, the other sensitive, assimilable, to a certain point, — to the roots of the spinal nerves. The first is furnished ‘by the filaments of — the seventh pair; while the second probably comes from the pneumogastrie _ nerve, and has annexed to it on its course the ganglion geniculare. The nerve — of Wrisberg perhaps concurs in the formation of this ganglion, but it is certainly not its principal source. Course and Termination.—The great petrous nerve, after being detached — from the facial, and forming with it an obtuse angle opening outwards, — enters the hiatus (or aqueduct) of Fallopius—a small passage running from . behind forward, in the substance of the petrous bone, above the oo rotunda, and cochlea. Arriving at the interior of the cavernous sinus, which it traverses, immersed in the blood that sinus contains, it receives a branch from the ganglionic plexus there, is lodged in the Videan fissure, then in the Videan canal, and in this manner gains the orbital hiatus, where it | separates into several branches—most frequently two—which join the posterior part of Meckel’s ganglion. It constitutes the motor root andy sympathetic filament of that ganglion. 3 2. Smatu Surerricran Perrous Nerve.—A very thin filament detached from the facial to the outside of the preceding, and likewise traversing the — petrous bone from behind to before to enter the otic ganglion, whose motor root it is. 3. Fiuament or tHe Srapzpios Musote (Tympanic).— The facial nerve, in its passage above and in front of the stapedius muscle, closely adheres to it, and gives it one, ona several, extremely short filaments. 4. Cuorpa Tympant (Fig. 342, 6).—This filament, also named the tympano-lingual nerve, arises at a very obtuse angle from the facial, near the external orifice of the aqueductus Fallopii. It penetrates the cavity of the tympanum by a particular opening, courses from its posterior to si se chee THE CRANIAL OR ENCEPHALIC NERVES. 725 anterior wall in describing a curve downwards, and passes among the chain of auditory bones, between the handle of the malleus and long branch of the incus. Escaping from the middle ear by a canal (fissura Glasert) on the limits of the mastoid and petrous portions of the temporal bone, it proceeds fi wards and downwards, and finally joins the gustatory nerve aftet a short course beneath the external pterygoid muscle, outside the guttural pouch. oe. 6. emeromonce Branco or THE Pynevumocastaic Nerve.—(See the description of the tenth pair.) _ 6. Ocorerro-Sry.oi Nerve. (Fig. 336, 3.) 7. Sryto-nvow Nerve. _ 8. Dicasrrio Nerve (Fig. 336, 4).— These three spring from a common fasciculus at the stylo-mastoid foramen, and ramify in their respective muscles, after a certain course beneath the parotid gland. _ 9. Crrvioan Branon (Figs. 336, 6).—This nerve has its origin almost in the middle of the subparotideal portion of the facial, near a particular loop thrown by that nerve around the posterior auricular artery, and often from loop itself. Tt afterwards traverses the parotid gland from within to without, and _ above to below, to descend at first on its external face, beneath the parotido- -auricularis muscle, then into the jugular channel, where it is lodged below the _ deep face, or in the substance of the subcutaneous muscle of the neck, which _ receives its terminal divisions near the anterior appendix of the sternum. In its course this nerve communicates with the inferior branches of the second, third, fourth, fifth, and sixth cervical pairs by branches from them; it sends numerous collateral filaments into the texture of the subcutaneous muscle. f | 10. Fiaments or tHe GurruraL Povon anp Parotip Gianp.— _ Remarkable for their number and tenuity, these filaments do not otherwise _ deserve _oasagad mention. 11. Postrertor Avricunar Nerve (Fig. 336, 2).—It commences at the stylo-mastoid foramen, is directed upwards beneath the parotid gland, _ accompanying the posterior auricular artery, and is distributed to the ry or muscles of the external ear. It sometimes offers at its origin a | Be lorcas to that embracing the posterior auricular artery. 12. Mippte Avricutar Nerve.~Most frequently this arise from the same point as the preceding nerve—it might be said in common with it— Dts terwands the base of the concha in traversing the parotid gland, and pierces the cartilage to supply the interconchal integument and the con- _ tractile fibres which cover its adherent face in some parts. 13. Ayreriorn Avricutar Nerve (Fig. 336, 5).—This is the largest of the three auricular nerves. After being detached from the facial nerve, _ opposite the cervical branch, and after ascending across the parotideal _ tissue, it gains the external face of the zygomatic process, where it meets _ the superficial divisions of the lachrymal nerve; it continues forward _ beneath the external parieto-auricular muscle, reaches the base of the orbital _ process at the supra-orbital foramen, there crossing the terminal branches of _ the nerve of that name; it then descends vertically within the orbit to below _ the nasal angle of the eye, where it mixes with the superficial divisions of the palpebro-nasal nerve, and finally terminates on the face in the lachrymal supernaso-labialis muscles, In its progress, it gives off numerous ramuscules to the anterior muscles of the car, the fronto-supra-orbital, and the orbicularis of the eye- lids, whose ‘euntractibility it excites, con ay il 726 THE NERVES. This nerve is remarkable for the relations it maintains with the terminal ramuscules of the three branches of the ophthalmic nerve, or fifth pair. ~ Although there do not exist any real anastomoses between it and these — various branches, it is customary to designate the reticular mass they form — in front of the ear and on the side of the face, as the anterior auricular plexus. — TrrmInaAL Branones or tHE Factan Nerve or Supzyeomaric CUS (Fig. 110, 11, 12).—The facial nerve, as we have seen, teyyninates in several branches, usually two, on arriving beneath the temporo-maxillary articula- = tion, where they join the superficial temporal nerve. After becoming — herd from the cranium than the superior cervical ganglion. e ganglion itself furn’shes the superior laryn nerve, which gives off, as in Man, the external laryngeal nerve. r ss There is nothing to indicate in the pharyngeal nerve, its disposition being absolutely the same as in the Ox. In the Dog the superior laryngeal has a curious disposition, which has not yet. to our knowledge, been described. Reaching the inner face of the thyroid cartilage, it gives off, as in the other animals, filaments to the glottis, epiglottis, base of the tongue, and : ; but the ramuscule of Gulien, which nearly equals the superior laryngeal ia volume, does not anastomose with the inferior laryngeal ; it gives a large brench to the crico-arytenoid muscle in passing to its surface, and then leaves the larynx to the inside of the recurrent, descending on the trachea as far as the entrance to the chest. In that corny: the descending branch of the superior laryngeal forms two divisions that com- m te with the ramuscules of verious other nerves passing into this region, On the tight side, the largest division receives a voluminous branch from the inferior cervical ; then the two divisions unite, and join the pneumogastric after it has turned round the brachial trunk, a little behind the point of emergence of the inferior laryngeal, 744 THE NERVES. On the left side the same arrangement is found; the anastomoses are larger’ numerous than on the right side; the branch follows, in an inverse direction, thee pursued by the recurrent nerve, to join the pneumogastric at the part where me aC originates from the latter. In this course, the branch gives large ramuscules to the cesop hegoe eee those distributed to the former either pass along the muscular tunic return — the nerve, or continue along the surface of that tube. In all cases, there is found on sides of the cesophagus a rich plexus formed by these filaments, as well as by — coming from the pharyngeal nerve. This branch also offers other peculiarities. Thus, it is very often found athe — laryngeal nerve for some distance, and sometimes at several points. When this “i in the upper part, at the larynx, as occurs in many cases, it appears to have an peo 8 mosis as in the Ox; but it is always easy to separate the two nerves, even in front ate specimens, and this ‘separation is greatly facilitated if the piece has been steeped all water acidulated by nitric acid. In the cervical portion, the pneumogastric nerve is closely united to the sympathetic, the separation of the nerves being no longer possible as in the Horse and Ox. : We have already described a portion of the inferior laryngeal nerve, in epoaking, of the tracheo-esophageal branch of the superior laryngeal. Comparison animals requires that we should transfer the latter to the recurrent. In the ae inferior laryngeal rises by two distinct branches, a short distance from each other, on ao right and left sides ; these may, or may not, lie together for some distance, but they never become fused. The external part of the nerve receives at intervals filaments — from the superior laryngeal branch, and it rarely gives very fine twigs to and cesophagus. The communications with the cardiac and tracheal nerves are. os chiefly made by the tracheo-cesophageal branch. The bronchial nerves are large and numerous. = The cesophageal plexus, which is furnished by the nerves of the same name, is larger A and finer than in the Horse. R There is nothing to note particularly in the termination of the nerves in the = stomach. The hypoglossal gives a long branch that passes to the sides of the larynx, and enters, the muscles on the anterior face of the trachea, = st x a - om ‘ COMPARISON OF THE CRANIAL NERVES OF MAN WITH THOSE OF ANIMALS. ; = The few modifications offered by the cranial nerves of Man, when compared with : those of animals, are dictated by the disposition of the parts and organs to whieh they F are distributed. We have spoken of the olfactory lobes when studying the brain, so that we need not again refer to them. The three succeeding nerves offer nothing worthy of mention, — Trigeminal nerve-—This has the same origin and divisions as in ani $ The frontal nerve of the ophthalmic portion divides into two branches ; these are inflected upwards on the margin of the orbit, and distributed to the skin of the for These two branches, well developed in the Dog, are distinguished as internal and external, The latter anastomoses with a branch of the facial. The nasal nerve, after spreading over the surface of the turbinated bones and the meatus, gives off a ramuscule that becomes subcutaneous in passing between the inferior border of the nasal bone aud cartilage of the nostril ; this is the naso-lobular nerve. The superior maxillary nerve leaves the cranium by the foramen rotundum, reaches the suborbital furrow, and spreads over the face by suborbital branches. Like that of — animals, it gives rise to an orbital ramuscule, and posterior and anterior dental a a Differences appese in the other branches etic, are furnished, in superior maxillary nerve: in Man these branches leave Meckel’s ganglion, ire ments leaving this ganglion are: 1, The pharyngeal nerve of Bock which is distributed in — the upper portion of the mucous membrane of the pharynx, in that of the Eustachian tube and the posterior orifice of the nasal cavities; 2, The palatine nerves—great or anterior—sent to the mucous membrane of the anterior portion of the palate; middle palatine, distributed to that of the soft palate, and posterior palatine, that goes to the two faces of ng soft palate and its muscles; 3, The nasal or spheno-palatine nerve. The inferior maxillary nerve closely resembles that of animals, the only differences consisting in: 1, The pe middle ee nerve rising direct from the maxill] 2, The limgual nerve is detached near the base of the cranium; 8, The su =’ temporal nerve furnishes, independently of the filaments uniting it to the ica, an 4 THE CRANIAL OR ENCEPHALIC NERVES. 745 Oo, soar ge branch that ascends in front of the ear, and terminates in the skin of 1 region. ‘ In Man, there is annexed to the fifth pair the submaxillary ganglion, which reccives a@ sensitive branch from the lingual, a motor filament from the chorda tympani, and thetic filaments; it gives off several emergent filaments, nearly all o which pass into the maxillary gland. ‘There is nothing to say of the internal motores oewlorum. ; Fucial.—In its collateral branches, the facial nerve of Man is absolutely the same as in animals, It has, however, a branch not described in them—the ramuscule of NERVES OF THE FACE AND SCALP. 1, Attrahens aurem muscle; 2, Anterior belly of occipito-frontalis; 3, Auriculo- temporal nerve; 4, Temporal branches of facial; 5, Attolens aurem muscle; 6, Supra-trochlear (5th); 7, Posterior belly of occipito-frontalis ; 8, Supra-orbital ; 9, Retrahens aurem muscle; 10, Temporal branch of temporo-orbital; 11, Small occipital ; 12, Malar branches of facial ; 13, Posterior auricular (7th); 14, Malar branch of temporo-malar (5); 15, Great occipital; 16, Infra-orbital branches of facial; 17, Facial; 18, Nasal; 19, Cervico-facial division of 7th; 20, Infra- orbital; 21, Branches of digastric and stylo-hyoid ; 22, Temporo-facial division of 7th; 23, Great auricular; 24, Buccal branches of facial; 25, Trapezius muscle ; 26, Buccinator (5th); 27, Splenius capitis; 28, Masseter; 29, Sterno-mastoideus ; 30, Supermaxillary branches of facial nerve; 31, Superficial cervical; 32, Mental ; 33, Platysma muscle; 34, Submaxillary branches of facial nerve. ngs hag which reaches the base of the tongue, where it is distributed by mixing with Poems pharyneeel. The termination much resembles that of the Dog. Two ipal branches have been named the temporo-facial and the cervico-facial. The receives the superficial temporal nerve, and describes an arch from which are detiched the temporal, frontal, palpebral, suborbital, and buccal ramuscules, which form the subparotideal plexus. The second, lodged in the parotid, passes towards the angle of the jaw, where it anastomoses with the cervical plexus; it furnishes the inferior buceal, mental, and cervical branches, I ta ag Re nerve commences and terminates as in Solipeds, and has the same relations. It furnishes the branches of ihe digastric and stylo-hyoid museles, the THE NERVES. Fig. 345, DISTRIBUTION OF THE EIGHTH PAIR OF NERVES ON LEFT SIDE, 1, Gasserian ganglion of 5th nerve; 2, Internal carotid artery; 3, Pharyngeal branch of pneumogastric; 4, Glosso-pharyngeal nerve; 5, Lingual nerve; 6, Spinal accessory; 7, Middle constrictor of pharynx; 8, Jugular (internal) vein, cut; 9, Superior laryngeal nerve; 10, Ganglion of trunk of pneumogastric; 11, Hypoglossal nerve on hyoglossus; 12, Ditto communicating with 8th and Ist cervical nerve; 13, External laryngeal nerve; 14, Second cervical looping with the first; 15, Pharyngeal plexus or inferior constrictor; 16, Superior cervical ganglion of sympathetic; 17, Superior cardiac nerve of pneumogastric; 18, Third cervical nerve; 19, Thyroid body; 20, Fourth cervical nerve; 21, 21, Left recurrent laryngeal nerve; 22, Spinal accessory communicating with cervical nerves; 23, Trachea; 24, Middle cervical ganglion of sympathetic; 25, Middle cardiac nerve of pneumogastric; 26, Phrenic nerve (cut); 27, Left carotid. artery; 28, Brachial plexus; 29, Phrenic nerve (cut); 30, Inferior cervical ganglion ef sympathetic; 31, Pulmonary plexus of- pneumogastric; 32, Thoracic aorta 33, (Ksophageal plexus; 54, Vena azygos superior; 35, Vena azygos minor , 36, Gangliated cord of sympathetic, THE SPINAL NERVES. 747 filament of the stylo-glossus muscle, and, fin ily, the tonsilitie ramuscules that form, around the amygdala, the fonsilar plerus. oa 'ric.—Formed by the union of the sensitive roots, the »neumogastric leaves ‘the cranial cavity by the posterior foramen lucerum; in the interior of that foramen it _ shows the jugular glion; a little lower, it has a second fusiform enlargement, the ‘orm plexus, which is found in the Dog. Here it receives the internal branch of the spinal accessory, or otherwise its motor roots. Beyond this gangliform enlargement, _ the pneumogastric is p'aced a little within the sympathetic, descends along the neck, enters the chest, and terminates on the stomach and in the solar plexus. e relations of the two pneumogastrics in the thoracic cavity are the same as in animals. In _ terminating in the semilunar ganglion, the two pneumogastrics unite and form an arch named the memorable loop of Wrisberg. The various anastomoses of the pneumogastric in Man offer nothing particular. The pharyngeal branches leave the gangliform plexus, and are constituted by the filaments carried to the pneumogastric by the internal root of the spinal accessory. They are two, three, or four in number, and form the pharyngeal plexus. The superior laryngeal nerve also arises from the gangliform plexus, and offers, as in Ruminants, a Galien branch that anastomoses, end to end, with a branch of the inferior The external laryngeal is furnished by this nerve; it is distributed to the i muscle of the pharynx, the crico-thyroid muscle, and the mucous membrane of the subglottic portion of the larynx and the ventricle of the glottis. The recurrent nerves affect a distribution analogous to that already made known. The ic also gives cardiac, pulmonary, and esophageal branches. The eardiac beside those coming from the sympathetic and recurrents, and enter the ganglion of Wrisberg, situated at the base of the heart. ‘The cesophageal branches are remarkable for their number and complexity, and form a veritable esophageal plexus. The gastric branches are also very numerous. cao Apenat accessory.—It presents bulbous roots whicli are well known, and medullary roots usually extend to the fifth cervical, and sometimes to the first dorsal. After its exit from the posterior foramen lacerum, it divides into two branches—an internal and external. _ The internal branch, formed by the bulbous roots, enters the gangliform plexus of the strie. The external branch comports itself as in animals. The lossal resembles that of Carnivora, and, like it, possesses a branch for the hyo-th and genio-hyoideus. CHAPTER IT. SPINAL NERVES. We designate as spinal, vertebral, or rachidian nerves, those which emanate from the spinal cord, and leave the vertebral canal by the intervertebral foramina to proceed to the various organs. They are estimated at 42 or 43 pairs, and are apportioned as follows in _ the five regions of the spine: cervical, 8 pairs; dorsal, 17 ‘pairs ; lumbar, 6 pairs ; sacral, 5 pairs; and coccygeal, 6 to 7 pairs. They differ from the encephalic nerves in closely resembling each other in the fundamental points of their constitution. All proceed from the lateral of the spinal cord by two orders of roots: one motor, the other sensitive (Fig. 317). In all, these two roots unite in a very short trunk in passing through the intervertebral foramen ; and this trunk divides almost immediately into two terminal branches: a superior, destined to the spinal muscles and the integuments covering them; the other, inferior, passes to the lateral and lower parts of the trunk or to the members. All send, from their inferior branch, one or more ramuscules to form the great sympathetic. The roots of the spinal nerves offer everywhere the same disposition ; each nerve is formed by two fasciculi of converging filaments, superior and inferior, which are naturally more numerous and large when they belong to 748 ; THE NER VES. voluminous trunks, as may be remarked in those proceeding from the t enlargements (or bulbs) of the spinal cord. The common axis of these t fasciculi affects a transverse direction in nearly all the spinal pairs; but that of the posterior nerves inclines more backwards as they reach the terminal extremity of the cord. The filaments of the superior fasciculi, or sensilive roots, are larger than the others, and emerge from the collateral suleus of the kit cord, Mey may be followed to the cells of the superior grey cornua. or. “The filaments of the inferior fasciculi, or motor roots, arise B= to the preceding, on the lower face of the cord, at a short distance from the — middle line, and on the limits of the inferior and lateral columns. They may — also be traced to the interior of the cord, as far as the inferior grey cornua, __ These filaments do not unite to form their common trunk until after — they have passed through the dura mater; this is an extremely short trunk that occupies the corresponding inter vertebral foramen, and presents on its upper face a ganglionic enlargement, which is exclusively placed on the course of its sensitive fibres; the motor filaments being simply = beside them, and do not mix with them until beyond the ganglion. Immediately after this union, a z filament is given off that enters the spinal canal to be distributed to the sinuses and the vertebra. After leaving the meningeal sheath, the radicular fasciculi of the nerves furnished by the terminal ex- ; tremity of the spinal cord, run a somewhat long course in the sacral canal, before finally uniting sad passing into the tissues ; the common fasciculus ‘ia collectively form at the posterior extremity “— spinal canal is named the cauda equina. = The distributive branches of the spinal nerves cannot be considered in a general manner, because of their diversity. We will study them successively in each region of the spine. a) a i *, Fig. 346. ArricLe I.—Crrvicat Nerves (8 Pairs). Surrrion Brancuxs.—The first passes through — GANGLION OF A SPINAL the superior foramen of the atlas, in company with see ReaON or the cerebro-spinal artery. It arrives in the inter- PUPPY, stice between the small oblique muscle of the head a, Superior root; b, In- and the posterior straight muscles, and divides imme-— ferior root; c, Ganglion diately into several divergent branches which are on the superior root; distributed to the three above-named muscles, the a paged of. anterior extremity of the great complexus, and the — and superior roots with cervico- and temporo-auricular muscles. The ramus-— those coming from the cule sent to the latter ascends within the concha, and ganglion; d, Superior breaks up into several filaments that supply the skin trunk of spinal nerve; of the external ear. e, Its inferior trunk. The second immediately furnishes enue rascal | cules to the great oblique muscle, beneath which it is placed, as well as ee the small oblique. It is afterwards directed backwards, comporting its like the succeeding ones. These diminish in volume from the third to the eighth. All pass through the intertransversales-colli muscles, and divide into several - THE CERVICAL NERVES. 749 branches, which are distributed to the muscles and integuments of the superior cervical region. Among these, the superficial, which are almost Setiesecitary in the two last pairs, reach the inner face of the splenius. The others, deep and more voluminous, cross the semispinalis colli, and, dividing, ascend between the great complexus and cervical ligament, to near the superior border of that large elastic lamina. They generally intereommuni- ate by several filaments, and in this way form a network on the inner face _ of the great complexus, which Girard named the deep cervical ‘ Invention Brancues.—These branches augment in size from the first to - the last, and separate into two perfectly distinct groups. The divisions of _ the first six cover the lateral and anterior parts of the neck, as well as the muscles of the breast. Usually anastomosing with each other by long _ communicating branches, they in this way form a vast nervous network traversed by two important nerves—the spinal accessory and cervical filament of the facial ; this is the superficial cervical plexus. The other two are united with the preceding by a filament passing between the sixth and seventh, soon becoming confounded with each other, as well as with the two first branches of the dorsal region ; they constitute, in common with the latter, the brachial plexus. : Without saying any more as to the disposition of this double plexus, we will pass to the particular description of each cervical pair of nerves. First.—Deeply situated beneath the transverse process of the atlas, this nerve leaves the anterior foramen of that vertebra, and accompanies the occipital artery and vein to place itself immediately between the anterior ra rectus capitis and rectus lateralis muscles. It then crosses the anterior great rectus capitis and the spinal accessory nerve, which it separates; and arrives, after describing a slight curve forward, near the thyroid gland, finally entering the subscapulo-hyoideus by several terminal divisions. Near its origin, this inferior branch of the first cervical nerve furnishes collateral ramuscules to the three recti muscles. Lower, it is in communica- tion with the superior cervical ganglion and the spinal accessory nerve by several filaments. At the carotid artery, it sends forwards, to the side of the larynx, a very fine branch that quickly divides into two ramuscules, one of which joins the great hypoglossal nerve, and the other goes to the thyro- hyoid muscle. It then throws off, from its convex side, several small descend- ing nerves, all of which are destined to the subscapulo-hyoid, sterno-hyoid, and thyroid muscles. One of these filaments, joined by a ramuscule from the second pair, is distinguished for its great length ; it may be followed to near the sternum, where it is expended in the fleshy mass common to the four muscles that extend from that bone to the larynx and os hyoides. Its constant disposition should obtain for it the name of precervical nerve. Second.—This descends beneath the great oblique muscle (obliquus posticus), crossing the direction of the rectus anticus major, and ramifyin therein by numerous branches. We specially indicate: 1, Those furnished to the latter muscle, and which are the shortest and deepest; 2, The atloid loop, a long, thick superficial branch, which enters the anterior portion of the levator humeri, and is directed forward and upward on the parotid gland, bending round the transverse process of the atlas: this ramuscule gives off filaments to the parotido-auricularis, as well as to the subcutaneons muscle of the face, and terminates in two branches of unequal volume, the largest of wiivh ascends on the outer side of the concha, and the other, situated behind, reaches the cervico-auricular muscles ; 3, Another superficial 750 THE NERVES. branch, which passes over the jugular, near the junction of the glosso-facial, — and divides into two ramuscules; these proceed forward with the facial vein to the intermaxillary space, where they are distributed to the — skin and subcutaneous muscle; 4, Anastomosing filaments, which unite it — to the two branches of the spinal nerve; 5, Accessory rainuscules to the cervical filament of the facial nerve ; 4, Two communicating branches which pass beneath the rectus anticus major: one going to the first, the other to the third pair of nerves; 7, A deep branch going to join the precervical “3 filament of the first pair, and directly throwing off some fine divisions to the subscapulo-hyoid muscle; 8, A last branch that arises at the intervertebral foramen, and passes at first, with the vertebral artery, into the trachelian (posterior) foramen of the "second vertebra, and afterwards those of the succeeding vertebra, to enter the inferior cervical ganglion of the sympathetic nerve, receiving on its course filaments from the 3rd, 4th, 5th, 6th, and 7th pairs. Third, fourth, fifth, and siath—Each of these crosses the intertrans- versales colli by a different interstice to that through which the corres superior branch passes. ‘They gain the inner face of the levator humeri, where they divide mto deep and superficial ramifications. The first are distributed to the deep muscles of the sides and anterior part of the neck and shoulders. Among them ought to be distinguished those which form a communication between the four pairs, and the third with the second. Very long and thin, these filaments lie on the side of the large muscular column formed in front of the cervical stalk by the rectus anticus, longus colli, and scalenus muscles, where they form sometimes arches, and at other times anastomoses by convergence. Those of the fifth and sixth pairs, uniting at the anterior border of the scalenus with a branch of the brachial plexus, constitute the diaphragmatic nerve, which will be noticed hereafter. The superficial ramuscules gain the external surface of the levator humeri by traversing its substance, or passing between its two portions. Much more numerous and larger than the preceding, they are distributed, in front, to the subcutaneous muscle of the neck, behind, to the trapezius, or below, to the levator humeri and superficial pectoral. Those passing to the last two muscles are very long and voluminous; they represent the acromial and — clavicular branches of the cervical plexus of Man. It may be remarked that the posterior filaments generally communicate with the spinal accessory, while the anterior ones, in meeting the cervical branch of the facial nerve on the jugular, often give it some anastomosing fibres. Seventh—An enormous branch comes from the interstice between the two portions of the scalenus, to pass entirely into the brachial plexus. It usually receives an anastomosing twig from the diaphragmatic filament furnished by the sixth pair. Kighth.—This is thicker than the preceding, and comports itself like it. It directly furnishes its anastomotic branch to the inferior cervical ganglion. Articte I1,—Dorsat Nerves (17 Puirs). These nerves, numbering seventeen pairs, comport themselves in an extremely simple and almost identical manner; so that their description i is not nearly so complicated as that of the nerves ‘of the cervical region. Superior Branouges.—They present two principal ramuscules destined to the spinal muscles, and to the skin of the dorso-lumbar region. One THE LUMBAR NERVES. 751 ascends towards the summit of the spinous processes of the dorsal vertebre, by passing between the semispinalis and longissimus dorsi ; the other is directed outwards, in traversing the substance of the latter muscle. __ _Iwrerton Brancues.—These are more considerable in size than the pera and descend into the intercostal spaces, between the pleura and internal intercostal muscles, or even in the texture of these. With the exception of the first, whose arrangement is different, they all pass at first over the head of the posterior rib to reach the convex border of the anterior _ one, and follow it to the extremity of the intercostal space. There they terminate in the following manner: those of the sternal _ ribs traverse the pectoral muscles, giving filaments to these, and are ; ded in the skin of the subthoracic region. Those of the asternal _ ribs enter the abdominal muscles, passing between the transversalis and rectus abdominis ; they also give cutaneous filaments to the skin of the belly. Near their origin, the inferior branches communicate with the great sympathetic, for the most part, by several filaments. In their course they furnish numerous fine ramuscules to the intercostal muscles, and, in addition, give off, about the middle of their length, a very thick division—the perforating intercostal branch, which traverses the costal muscles and des:ends beneath the panniculus carnosus, ramifying partly in that muscle and partly in the skin. The most anterior perforating branches generally anastomose with the subcutaneous thoracic branch of the brachial exus. With regard to the first dorsal pair, its inferior branch enters the latter plexus ; but it nevertheless furnishes an intercostal branch, always extremely slender, which passes over the external intercostal muscle to be expended in its substance before arriving at the sternum. The second pair also concurs in the formation of the brachial plexus, though only by a small branch. Articre ITI.—Lumpar Nerves (6 Pairs). Surrrion Brancnes.—Destined to the spinal muscles and the integu- ments of the loins and croup, these are larger than the corresponding branches of the dorsal region, and present an analogous disposition; they Lee superior ramuscules to the muscles of the spine, and very long external ivisions which pass through these muscles to be distributed to the skin of the croup. Inventor Brancnes.-—The first, comprised in the interval separating the last rib from the first lumbar transverse process, between the quadratus lumborum and the psoas magnus, passes downwards and backwards until it gets between the transverse and internal oblique muscles of the abdomen, to which it gives filaments, and is finally distributed in the great rectus muscle. Above the superior border of the internal oblique muscle, it furnishes a perforating branch to the skin of the flank and the posterior part of the iculus carnosus. The second, disposed in the same manner as the preceding, follows an analogous course, and breaks up into several divisions which are lost in the small oblique muscle. From one of these sometimes emanates a slender filament, which joins one of the inguinal nerves of the third pair. We must not overlook, in the enumeration of the branches emitted by this second pair of lunivur nerves, the two perforating branches which descend in front, and on the inside, of the-thigh, to be distributed to the skin of the flank and the internal crural region. 752 THE NERVES. The third,! also passes outwards, above the psoas muscles, which receive ~~ from it several divisions, and ramifies in the vameolee of the flank, It! at also perforating nerves, destined to the inguinal region, and these comport themselves in a sufficiently interesting manner to merit particular ment They are usually three in number: an internal and two external in nerves. The three pass at first beneath the peritoneum, and are directed backwards, downwards, and outwards, towards the inguinal canal, which — they enter, one to the inside, the other to the outside of the sperma 4 cord. They give off some filaments to the cremaster and abdominal muscles, and at last ramify in the envelopes of the testicle, the she: | and the skin of the inguinal region. The two. external nerves are o confounded in a single trunk on their arrival at the cremaster muscle. disposition they affect at their origin is extremely variable; sometimes have each a distinct commencement, and separately traverse either the ll or large psoas muscle, or the space between these ; and, at other times, the RS internal and one of the external inguinal nerves ‘proceed from a a trunk at the intervertebral foramen, the second external nerve then alone towards the external border of the great psoas muscle. Most tl the internal nerve receives a branch from the fourth pair, and it is even sometimes entirely formed by that branch. This variation in arrangement — is not, however, the exclusive appanage of the inguinal nerves; we have — seen the third pair only supply these three nerves and the filaments of the muscles, without being prolonged into the muscles of the flank. . The fourth? pierces the small psoas muscle, and enters the space separating — it from its congener—the great psoas. After passing between the peritoneum and the lumbo-iliae aponeurosis, it arrives below the angle of the haunch, — and makes its exit from the abdomen ; it then descends within, and in front — of, the fascia lata muscle, and accompanying the divisions of the circumflex iliac artery, it is prolonged to the stifle, where it is expended in the skin. — At its origin, it abandons: 1, A thick, short branch to the great psoas muscle; 2, A large anastomosing branch which concurs in the formation of ; the lumbo-sacral plexus; 3, A filament that joins the internal : nerve’ furnished by the third pair. We have already mentioned that this nerve sometimes emanates entirely from the fourth pair. The fifth and siath, much more voluminous than the preceding, unite, and, with the three first sacral pairs, form the nervous plexus of the abdominal limb. All the inferior lumbar branches communicate with the great sympathetic — by several filaments, which pass across the fasciculi of the small psoas muscle ; — and all communicate with each other: the two last by fusion of their fibres, and the first five by means of more or less voluminous anastomotic branches’ which are far from being constant. Articte TV.—Sacrat Nerves (5 Pairs). We describe, as sacral nerves, not only the four double cords which © escape by the lateral foramina of the os sacrum, but also the nerve that passes through the intervertebral foramen between that bone and the last . lumbar vertebra. .- Surrrior Brancues.—These are small ramuscules that pass chou he — 1 Representing the abdomino-genital and femoro-genital branches of Man, ? The femoro-cutaneous branch of the lumbar plexus of Man. THE COMPOSITE NERVES. 783 supersacral foramen, reach the muscles lodged on the sides of the sacral spine, and terminate in the skin of the croup. - Invention Brancues.—Thick nervous trunks, which diminish in volume from the first to the fifth, and leave the sacral canal to pass downwards and ‘backwards on the sides of the pelvic cavity. _ The first, second, and third are directed towards the great ischiatic opening, and are united into a wide nervous band that constitutes the pelvic portion __ of the lumbo-sacral plexus, to be described at another time. _ The fourth and. jifth course along the side of the pelvic cavity, in the texture of the sacro-sciatic ligament, or even within it; united at their base by an anastomosing filament, they do not usually communicate in a direct manner with the fasciculus formed by the three first pairs. The fourth constitutes the internal pudic nerve, which passes between the two roots of the corpora cavernosa in bending round the ischial arch, where it lies nearly alongside its fellow of the opposite side. This nerve after- wards descends on the dorsal border of the penis in the midst of the magni- ficent venous plexus of that organ, describing flexuosities which allow it to adapt itself to the elongation of the penis. Arriving at the extremity of the organ, it terminates in numerous divisions in the proper erectile tissue of this or in the mucous membrane covering it. On its course it emits very long fiexuous branches, whose ultimate ramifications enter the corpora cavernosa, or go to the urethral canal ; before leaving the pelvis, it gives off, be- hind, two thin ramuscules destined to the muscles and skin of the perineo-anal region. These ramuscules, like the principal trunk, receive anastomotic fila- ments from one of the ischio-muscular branches of the lumbo-sacral plexus. The fifth is the anal or hemorrhoidal nerve. It passes backward, above the p ing, and is distributed to the sphincter muscle and the surround- ing integuments. Before quitting the pelvis, it gives a ramuscule to the r ani. The five inferior sacral branches emit, near their origin, a more or less slender filament that proceeds to the pelvic or hypogastric plexus. The anastomotic divisions, through which they communicate with the sympathetic chain, are generally thick, short, and multiple. ArricLe V.—Covcyerat Nerves (6 to 7 Pairs). In the coccygeal region are found two pairs of nerves, one placed beneath the depressor muscle of the tail, the other below the lateral . gaero-coccygeal muscle. These two nerves extend to the extremity of the tail, throwing off on their track some muscular and cutaneous filaments. They are formed by the superior and inferior branches of the coccygeal nerves, which gradually amalgamate to form the two trunks. These coccygeal branches are six or seven in number, and very distinct ; they diminish in volume from the first to the last. The first only gives a slender filament for the formation of each coccygeal trunk ; it is chiefly _ expended in the integuments and muscles at the base of the tail. Anrticte VI.—Composire Nerves rormep sy THE Inrerton BRANCHES OF THE Serna Nerves. We already know that these nerves represent three groups: 1, The diaphragmatic nerve ; 2, The brachial plexus; 3, The lumbo-sacral plexus, They will be studied in this order. , - © 754 THE NERVES. DIAPHRAGMATIO (OR PHRENIC) NERVE. The diaphragmatic nerve (the internal respiratory nerve of Bell) is by two principal branches, aud a small accessory ramuscule whase presence is not constant. The latter comes from the fifth cervical pair; the two others proceed, one from the next pair, the other from the brachial plexus, The ad hes from the sixth pair pierces the inferior scalenus muscle mr Be within to without, gives off a filament to the brachial plexus, and y obliquely backwards to the surface of the muscle it passes through, to unite, — at the entrance to the chest, with the branch of that plexus. This latter branch, generally shorter and thicker, comes exclusively from the seventh — a cervical pair. US The trunk of the diaphragmatic nerve, formed in this manner, after receiving the branch of the fifth pair—when it exists, passes within the — axillary artery, along with the pneumogastric nerve, and often at this plas 2 though not always, obtains a filament from the great sympathetic. It then gains the side of the base of the heart, passing beneath the pleura, and — finally attains the phrenic centre, after a course of at least eight inches — between the two laminz of the posterior mediastinum—the left nerve in the proper mediastinum, while that of the right side lies in the serous septum intended for the posteri ior vena cava, ‘ ’ Even before its arrival at the aponeurotic centre, this nerve divides into several branches, whose ramifications pass to the sides of the pillars of te muscle. “4 BRACHIAL PLEXUS. “a This plexus comprises an enormous fasciculus of nerves, situated between the thoracic parietes and the inner face of the anterior member, formed by the inferior branches of the sixth, seventh and eighth cervical, and the two first dorsal pairs, and principally destined to the muscles and integuments of that limb. Mode of constitution—The sixth cervical pair only assists in the forma- tion of this plexus by the slender filament from its diaphragmatic branch; __ but the next two are entirely devoted to it, as well as the first dorsal, with the exception of a very thin ramuscule, which constitutes the first intereostal nerve. The root furnished by the second dorsal pair only represents a very — small part of its inferior branch, the other portion forming a somewhat — voluminous intercostal nerve. The various branches converge camenda each other, and gain the interac > between the two portions of the scalenus muscle (if we consider it as one), where they unite, and become confounded into a single fasciculus by sending — filaments and ramuscules to each other; this fasciculus soon separates into — a certain number of divisions, whose disposition will be referred to presently, It will be remarked that the intercrossing of the branches composing the — brachial plexus does not occur in a confused and irregular fashion, and — if the reticulation of the ramuscules passing from one to another does not take place in a constant manner, it is, at any rate, far from being inextricable, — It is easy to follow the filaments from any pair of nerves for a certain distance in the divisions given off by the brachial plexus, especially after maceration in dilute nitric acid. This originating fasciculus of the brachial plexus is very wide and short. It is at first comprised between the superior portion of the scalenus (or superior scalenus) and the longus colli. in passing between the two portions of that muscle, it bends round the first rib - THE BRACHIAL PLEXUS. 755 ____ by its posterior border, and corresponds inwardly to the vertebral artery and _ vein, as well as to the nervous vertebral filament proceeding to the sympathetic, and accompanying these vessels. Mode of distribution—Immediately after leaving the interspace in the ___ sealenus, the brachial plexus arrives beneath the shoulder, near the scapulo- humeral angle. There it divides into a certain number of branches, amongst which it is impossible to distinguish the terminal divisions and collateral 9a Without noticing this distinction, however, we will describe _ them in succession, commencing with those that pass to the trunk, and after- _ wards those which are destined for the limb. The latter will be examined in the following order: first, the shortest, or those which proceed to the upper oy of the member, and next, the longest branches, or those passing to the foot. a All these divisions are named and classified in the following enumera- 1. Diaphragmatic branches. 2. Angularis and rhomboideal branch. 3. Serratus magnus or superior thoracic branch. 4. Pectoral or inferior thoracic branches. 5. Subcutaneous thoracic branch. 6. Latissimus dorsi or great dorsal branch. ; 7. Azillary nerve. 8. Adductor brachii or teres major branches. : 9. Subscapular branches. 10. Superscapular nerve. 11. Anterior brachial or musculo-cutaneous nerve. 12. Radial nerve. 13. Ulnar or cubito-cutaneous nerve. 14, Median or cubito-plantar nerve. PREPARATION OF THE BracutaL PLexvus.—The animal is placed in the first position, and slightly inclined to one side by allowing one of the anterior limbs to hang un- i The pectoral muscles are then excised close to their insertion in the unfixed limb, and turned upwards, yeni, Sere in this position by the chain tentacula which are detached superiorly = _ “ars Base unites ve extremities of the two _ suspensory diagonal bars. Care sho taken to separate the pectoralis magnus from the panniculis, in allowing the latter to fall on the table along with the limb. By tear- ing the considerable mass of cellular tissue surrounding the nerves of the brachial plexus, these soon appear, and may be isolated with the greatest facility. It is _ advisable in this dissection to preserve the arteries; and it is also of importance to lave the ting intercostal branches intact, in order to observe the anastomoses of these with the subcutaneous thoracic division. In this operation, the anterior limb is very much separated from the trunk, and the relations of the nerves are necessarily more or less changed; but it exhibits the whole of the _ in the most perfect manner. trace the divisions of the principal nerves from this plexus, a limb entirely _ removed from the body is made use of, and, if possible, with the arteries injected. The nerves are then found in their natural relations, and can be more readily dissected. Figures 347, 348 will guide the student in looking for these nervous divisions. 1. Diaphragmatic Branches. See the description of the diaphragmatic nerve above. 2. The Angularis and Rhomboideal Branch. (Fig. 347, 7.) Entirely furnished by the sixth cervical pair, this branch is directed upwards to the surface of the angularis (anterior portion of the serratus 302 756 THE NERVES. magnus). It soon divides into several filaments, which are wholly expended in the substance of that muscle, the serratus magnus, and the rhomboideus, — The filament supplying the latter is slender and very long, and, to reach its destination, passes through the angularis. ‘ 8. Serratus Magnus, or Superior Thoracic Branch. (Fig. 847, 8.) wor g This very remarkable branch proceeds by two principal portions from — J the fasciculus common to all the divisions of the brachial plexus: one emanating from the sixth cervical pair; the other from the seventh, and always traversing the last fasciculus of the scalenus before joining the first. The single branch resulting from the union of these two roots is thin and very wide. It passes back to the surface of the serratus magnus; crossing the direction of its fibres, and is expended in its substance, sending regularly- arranged ramifications upwards and downwards. a ‘ This is the respiratory nerve of Bell. 4, Pectoral or Inferior Thoracic Branches. Five principal are distinguished : 1. One emanating from the sixth and seventh cervical pairs, particularly the former, and passing to the internal face of the sterno-prescapularis (or pectoralis), to ramify exclusively among its fibres, after dividing into two branches: an anterior, short and thick, and a posterior, long and slender (Fig. 347, 10). 2. A second branch, arising from the anterior brachial and cubito-plantar, or median nerves, by two roots, which join in forming an arch beneath the maxillary artery. , It passes between the two portions of the deep pectoral muscle, and terminates in the superficial one, after furnishing some ramuscules to the pectoralis magnus by means of a long thin filament which is carried back to the external surface of that muscle (Fig. 347, 11). 5. The other three, destined to the pectoralis magnus, generally come from the trunk that constitutes the subcutaneous thoracic branch. Com- prised between the serratus magnus, and pectoralis magnus, they are — directed downward and backward, and enter the latter muscle. One of them, longer and thicker than the other, follows the course of the spur vein, _ 5 Subcutaneous Thoracic Branch, (Fig. 347, 9.) This is a very remarkable nerve, arising from the brachial plexus by a trunk common toitand the ulnar nerve. Placed at first to the inside of that nerve, it soon leaves it to pass backward to the internal face of the caput magnum and the panniculus carnosus. In its long course, it acts as a satellite to the spur vein, above which it is situated. It may be followed — to the flank, where its terminal divisions are lost in the substance of the subcutaneous muscle. Those it gives off are also destined to that musele ;— they anastomose with the majority of the perforating intercostal nerves, — forming an elaborate network on the inner face of the panniculus, One of its branches, along with a voluminous perforating nerve, bends round the inferior border of the latissimus dorsi, and passes forward — to enter the scapulo-humeral portion of the subcutaneous muscle. a THE BRACHIAL PLEXUS. Fig. 347. * 1, NERVES OF THE BRACHIAL PLEXUS. of that branch.—a, Humeral artery ; 8, Posterior radial artery. 757 Diaphragmatic branch of the sixth cervical pair, furnishing a branch to the brachial plexus; Seventh cervical pair ; Eighth cervical pair; First dorsal pair; Second dorsal pair; Great dorsal branch; Angularis and rhomboid- eal branch; 8, Superior thoracic branch; 9, Sub- cutaneous thoracic branch, giving rise, near its origin, to the three inferior tho- racic branches; 12, Nerve of the adductor of the arm; 13, Axillary nerve ; 14, Subscapular nerves; 15, Superscapular nerve ; 16, Radial nerve; 17, Anterior brachial nerve; 18, Ulnar nerve; 19, Its internal cutaneous branch ; 20, Median nerve; 21, Its antibrachial musculo- cutaneous branch ; 22, 22, 22, Superficial ramuscules “-~ “ +. SS Lt ym go po - "158 THE NERVES. a 6. Great Dorsal Branch. (Fig. 847, 6.) a Formed of fibres, the larger portion of which come from the eighth 4 cervical pair, this branch proceeds backwards and upwards to the internal — face of the latissimus dorsi, and is soon expended in that muscle. Itislong and thick, 7. Axillary or Circumflex Nerve. (Fig. 847, 13.) a, Somewhat considerable in volume, this nerve is furnished directly by the eighth cervical pair. It passes backward and downward on the internal face of the subscapularis muscle, to the interstice between it and the adductor _ of the arm, where it crosses the subscapular artery. It proceeds behind : the scapulo-humeral articulation, along with the circumflex artery, enters — between the short abductor of the arm and the caput magnum and medium, and arriving beneath the abductor brachii, it divides into several diverging branches, destined to the two abductors, the levator humeri, and even to the integuments covering the anterior region of the arm. Before entering the space that lodges the subscapular artery, it sends filaments to the teres internus. 8. Nerve of the Adductor of the Armor Teres Major, (Fig. 347, 12.) This arises from the eighth cervical pair, like the preceding, by the same trunk, and passes backward, at first on the subscapularis muscle, then the adductor, in the substance of which it disappears by numerous filaments. 9. Subscapular Branches. (Fig. 347, 14.) These branches are two in number, and are generally derived from the trunk of the seventh pair. After a short course backwards, they divide into several ramuscules which pass among the fibres of the subscapularis muscle, 10, Superscapular Nerve. (Fig. 347, 15). Very short and thick, this nerve is formed by the sixth and seventh cervical pairs. After a brief course backwards, between the angularis on the one side, and the pectoralis prescapularis and superspinatus on the other, it gains the space between the latter muscle and the subscapularis, and enters it a little above the super- or prescapular artery. It is then carried to the external face of the scapula, after bending round the anterior border of that bone, passes across the acromion spine, and ascends to the ~ subspinous fossa, to expend itself in the muscle occupying this space. Onits passage beneath the superspinatus, it gives off several ramuscules to that — muscle. F 11. Anterior Brachial or Musculo-cutaneous Nerve. (Fig. 847, 17.) This nerve proceeds from the seventh and eighth cervical pairs, descends — to the internal face of thé scapulo-humeral articulation, and meets the axillary artery, which it crosses outwardly, at an acute angle. It then joins the median nerve by a large short branch, that passes beneath the artery and forms a loop around it; descending in front of the median nerve, to the bifurcation of the coraco-humeralis, it insinuates itself between _ the two branches of that muscle, and breaking up into several ascending THE BRACHIAL PLEXUS, and descending ramuscules, ‘enters the substance of the coraco-radialis. It also fur- nishes filaments to the coraco- humeralis, ,before its passage between the two branches of that muscle. Besides this, it concurs, by a small branch, in the formation of one of the anterior thoracic nerves. 12. Radial Nerve. (Figs. 347, : 16; 348, 3.) This is certainly the largest nerve furnished by the brachial plexus. It arises chiefly from the first dorsal pair, and is directed backwards and down- wards, on the inner face of the subscapularis and adductor mus- cle of the arm, whose direction it crosses. In this portion of its course, it proceeds parallel to the humeral artery, from which it is separated by the ulnar nerve. Arriving at the deep humeral artery, which it leaves on the outside, it passes behind the humerus with the divisions of that artery, and enters be- tween the large extensor and short flexor of the fore-arm. ' After creeping along the pos- terior border of the latter muscle, if gains the anterior face of the ulnar and radial ar- ticulations, where it is covered by the two principal extensors of the metacarpus and the pha- langes, and meeting the radial artery, accompanies it on to the oblique extensor of the meta- carpus. There it terminates by two branches which enter the texture of that muscle. 1, Subscapular nerve; 2, Axil- lary nerve; 3, Radial nerve; 4, Superficial ramuscule of the musculo-cutaneous nerve; 5, Ulnar nerve; 6, Its terminal cutaneous branch.—a, Anterior radial artery. EXTERNAL NERVES OF THE ANTERIOR LIMB. 760 : THE NERVES. In its course, if successively gives off: 1. Before leaving the internal face of the limb, to pass beneath thes mass of extensor muscles of the fore-arm, a very thick fasciculus, composed of several branches—descending and ascending. The latter bend round ‘he terminal tendon common to the latissimus dorsi and teres internus, to become lost in the body of the great extensor; the others reach either the — | long and middle extensors, or the inferior portion of the principal muscle— the large extensor. 2. Behind the arm, filaments to the short and small extensors of the fore-arm, and several cutaneous ramuscules, disengaged from beneath the short extensor, that descend beneath the skin on the anterior face of that part. external flexor of the metacarpus, and the two extensors of the digit. In brief, we see that the radial nerve animates the whole mass of the extensor muscles of the fore-arm and foot, besides a flexor of the latter, and that it endows the integument of the anterior antibrachial region ‘with sensibility. . e 13. Ulnar, or Cubito-cutaneous Nerve. (Figs. 847, 18; 348, 5.) _ Chiefly formed by fibres from the dorsal pairs, this nerve, less consider- able in volume than the preceding, proceeds backward and downward, and places itself behind the humeral artery, which it accompanies to -below the origin of the deep humeral. After crossing the latter vessel, it passes between the long and middle extensors of the fore-arm, and gains the inner side of the elbow, running over the epicondyle, below the ulnar band of the oblique flexor of the metacarpus. It follows the posterior border of that muscle to near the supercarpal or pisiform bone, where it terminates by two branches. In the latter part of its course, it lies beneath the anti- brachial aponeurosis, accompanied by a division of the epicondyloid artery. One of the two branches, the cutaneous (Fig. 348, 6), crosses the space between the terminal tendons of the external and oblique flexor muscles of the metacarpus, as well as the antibrachial aponeurosis, to spread itself in * several ascending horizontal and descending filaments, beneath the skin of the fore-arm, the anterior face of the knee, and the external side of the cannon. — ‘The other branch, with a ramuscule from the median nerve, constitutes the external plantar nerve. In its course, the ulnar nerve gives off two fasciculi of collateral branches. The first (Fig. 347, 19) is detached from the principal trunk a little above — the epicondyloid artery, and passes backward and downward between the long extensor of the fore-arm and the pectoralis transversus, supplying some filaments to the latter, and traverses it to become subcutaneous, and to be distributed to the skin of the fore-arm, beneath the elbow. The second arises at the epicondyle, and is destined to all the muscles of the posterior antibrachial region, except the external and internal flexors of the — metacarpus. 14. Median, or Cubito-plantar Nerve. (Fig. 347, 20.) This nerve is composed of fibres coming from the dorsal and eighth ; _ cervical pairs. It is detached from the posterior part of the trunk of the — plexus to proceed to the axillary artery, where it forms an anastomosis with 3. In the antibrachial region, branches to the anterior extensor and — " THE BRACHIAL PLEXUS. 761 the anterior brachial nerve, through the loop already noticed when describing that nerve as being formed by filaments passing from one cord to the other. Leaving this point, it is placed in front of the humeral artery, and accompanies it to its terminal bifurcation ; then it continues to descend on the inner face of the limb, along with the principal branch of that artery — the posterior radial—until it reaches the ulnar articulation, where it responds to the internal ligament of that joint, and where it crosses, at a very acute angle, the direction of its satellite vessel to become posterior. This position it inverts below the articulation, when it assumes, and preserves for the greatest part of its extent, its antibrachial course, remaining always a little more superficial than the artery. Above the lower third of the fore- arm, it bifurcates to form the plantar nerves. Tn its course, this nerve successively furnishes : 1. Before its arrival on the axillary artery, one of the originating branches of the thoracic nerve destined to the superficial pectoral muscle. 2. At the middle of the humerus, a long branch, represented in Man by _ that portion of the musculo-cutaneous nerve which proceeds to the anterior brachial muscle and the skin of the fore-arm. This branch enters beneath the coraco-radialis or biceps, and forms two divisions; one of which is ed in the short flexor of the forearm; while the other passes between that muscle and its congener, the long flexor, to become superficial and gain the internal aspect of the limb, when it breaks up into two principal filaments, which pass to the external face of the antibrachial aponeurosis, and accompany with their divisions the two subcutaneous veins of the fore-arm to below the carpal region (Fig. 347, 21, 22). 8. In the antibrachial region, and at various elevations, but particularly below the ulnar articulation, ramifications to the internal flexor of the metacarpus and the two flexors of the phalanges. Puantar Nerves.—These nerves, two in number, are distinguished as internal and external. The internal plantar nerve, one of the terminal branches of the median nerve, lies beside the collateral artery of the cannon, and follows that vessel along the perforans tendon to near the fetlock, where it ends in several digital branches. In its track it furnishes a number of cutaneous me ramuscules, and an anastomosing branch, which, after being detached from the incipal trunk, about the middle of the cannon, bends obliquely behind the xor tendons to join the external plantar nerve. This is formed by the union of two branches: one coming from the ulnar nerve, the other from the median, and joining the first at the upper border of the pisiform bone, after passing beneath the inferior extremity of the oblique flexor of the metacarpus. This nerve, which accompanies the external collateral vein of the cannon for its entire length, descends with it, and with an arteriole that coneurs in forming the subcarpal arch, outside the flexor tendons, in a jal fibrous channel of the carpal sheath. Near the superior extremity of e cannon, within the head of the external metacarpal bone, it sends on the posterior face of the suspensory ligament of the fetlock a deep plantar branch, chiefly destined to the fleshy portion of the interosseous muscles, It is the analogue of the deep palmar branch of the ulnar nerve in Man. Continuing its descending course along the perforans tendon, it throws off some superficial metacarpal ramuscules, receives the accessory branch supplied by the internal nerve, and terminates, like the latter, in a number of digital branches on arriving at the fetlock; these it now remains for us to examine. 762 THE NERVES. The digital branches, or collaterals of the digit, and the terminal branche: of the plantar nerves, are three in number on each side, and accompany the — digital artery and vein, which, at some points, they cover with their divisions. — Fig. 349, ! 6 % H j 4 V.VEAM. se NERVES OF THE DIGIT. p, Plantar nerve; B, Median branch; ¢, Anterior branch; D, Digital artery; H, Inconstant division given off to the cartilaginous bulbs; 1, 1, Branch to the plantar cushion; K, Transverse coronary branch; M, Podophyllous branch; 0, Preplantar branch; Q, Descending ramuscule to the fissure of the patilobes; R, Ramuscules accompanying the digital artery in the plantar fissure; v, Vein _ whose presence is not constant, and which sometimes accompanies the plantar nerve throughout its phalangeal course, THE BRACHIAL PLEXUS. 763 ‘hey separate from one another nearly at the insertion of the suspensory | t into the sesamoid bones. One of them descends in front of the vein; another passes between the two vessels; while the third follows the artery behind. They may, therefore, be distinguished, according to their position, into anterior, middle, and posterior (Fig. 349, m, 0, R). The anterior branch distributes its collateral divisions to the skin on the anterior face of the digit, and its terminal ramuscules in the coronary cushion, The middle branch frequently anastomoses with the other two, par- ticularly with the anterior, and to such a degree as to be scarcely dis- tinguished from it; it enters the coronary cushion and the podophyllous tissue The posterior branch, much more considerable than the preceding, and a veritable continuation of the plantar nerve, is at first superposed on the digital artery, then it is placed immediately behind that vessel. It descends with it to near the basilar process of the third phalanx, follows the pre- plantar ungueal artery into the lateral fissure of that phalanx, and, like that vessel, expends itself in the midst of the podophyllous tissue, as well as in the osseous structure. This branch gives off numerous ramuscules on its course. Of these there may be more particularly noticed: 1, Some posterior divisions, distributed behind the flexor tendons, especially at the fetlock ; 2, A satellite branch to the artery of the plantar cushion ; 3, A filament arising below the lateral cartilage, passing forward, in proximity to the anterior branch of the arterial coronary circle, and becoming lost in the meshes of the deep venous network of the cartilage; 4, A small podo- phyllous division, whose point of origin is placed at the same height as the preceding filament, but opposite it, and which descends on the retrossal process, where it traverses the cartilaginous tissue to pass to the podo- phyllous reticulation, after distributing posterior ramuscules to the plantar cushion; 5, Several extremely fine filaments enlaced around the plantar ungueal artery, and with it penetrating to the interior of the os pedis; some of these filaments ascend to the nerve of the opposite side.’ DIFFERENTIAL CHARACTERS IN THE BRACHIAL PLEXUS OF OTHER THAN SOLIPED ANIMALS. In the domesticated mammals, the nerves of the brachial plexus do not offer any very oo differences in the upper part of the limb; these only become apparent in its section. Romrvants.—The branches of the plexus, the same in number as in the Horse, are relatively more voluminous than in that animal. In the Oz they are often flexuous in their upper part. In the Sheep, we have found that the diaphragmatic nerre is formed by a single filament, detached from the branch the sixth cervical nerve gives to the brachial plexus. There are no differences to signalise in the branch of the angularis and rhomboideus, in the branches of the pectoral muscles, the subcutaneous thoracic branch, or the anterior brachial or musculo-cutaneous nerve, 1 It is because we conform to established usages, and are unwilling to force analogies, that we preserve the designations of “ plantar nerves,” and “ digital branches,” as well as the above manner of describing them. Comparative anatomy desires other names and a different description ; for it demonstrates that the external plantar nerve corresponds to the interosseous of the first space in pentadactylous awn the internal plantar to the interosseous of the third space, and the branch extending from the internal to the external plantar, to the interosseous of the second space, and which only virtually exists in the Horse, in consequence of the fusion of the second and third metacarpal bone, and which is prolonged to the phalanges. It also shows that the digital branches are the exact fe eon ee of the collaterals of the digits which result, in the pentadactylous species, from a bifurcation of each interosseous nerve. 764 THE NERVES. a The nerve of the serratus magnus does not show the branch which, in the Horse, — arises from the sixth nerve and passes through the secalenus; but on the surface of the serratus magnus it receives a filament from the branch of the angularis. The latter is detached from the sixth. ; -1_- = The branch of the great dorsal muscle and the azvillary nerve are confounded at their — origin, and also adhere to one of the two branches of the subscapularis nerve. The — Fig. 350. NOUGUES er NICOLFL DEL V.VERMORCKFEN = S.C NERVES OF THE DIGITAL REGION OF RUMINANTS; POSTERIOR FACE, ’ M, Internal plantar nerve, a continuation of the median; C, Internal plantar nerve, __ a continuation of the ulnar; 1, Branch of the gros furnishing, 2, the internal collateral nerve of the internal digit ; 3, Branch giving off the internal collaterals a - of the digits; 1’, Branch of the internal plantar that joins the external plantar; __ 4, External collateral of the external digit. second branch of the latter is free throughout, and distributed in the muscle of the same name, along with some filaments furnished by the superscapularis. The radial nerve, when it reaches the teres major, divides into three branches: one is THE BRACHIAL PLEXUS, 765 around the arm, and is placed between the anterior brachial and the mass of the olecranian muscles, it Rabel: 1, Muscular branches that pass immediately beneath the extensors of the metacarpus and phalanges; 2, A sensitive branch that leaves this muscular interstice to become subcutaneous. This cutaneous branch of the radial gains the inner face of the fore-arm, and divides in two branches that descend parallel to the median subcutaneous vein. One of these is lost around the carpus; the other is placed a little in front of the metacarpus, and reaches the metacarpo-phalangeal articulation, where it terminates by two principal filaments that constitute the dorsal collaterals of the ts; there is a third which crosses the interdigital to anastomose with the palmar The ulnar and median nerve of Ruminants lie beside each other, as far as the middle of the arm. This double cord is situated at the surface of the humeral artery ; at the earpus the two nerves offer the same distribution as in the Horse, but beyond this there are some differences. The ulnar does not receive a branch from the median at the us, and if forms the external plantar nerve or interosseous palmar of the first space, placed at the external border of the flexor tendons. This nerve is reinforced by a filament detached from the external plantar, that joins it a little above the fetlock-joint; it gives ramuscules to the eee and is then continued by the external collateral nerve of the outer digit, into the orny claw. median is continued by the internal plantar, or interosseous palmar of the third ‘e. Towards the inferior third of the metacarpus, it divides into three branches: the passes to the external plantar ; the second proceeds to the interdigital space, where it bifurcates to form the internal collateral palmar nerves of the external digit, and external collaterul of the internal digit; the third gives some filaments to the ergot, and passes eas 3 the digital region. where it constitutes the internal collateral of the internal digit. 16.—Thiree fusciculi are detached from the brachial plexus; the posterior is the most voluminous, and furnishes the radial, median, and cubital. The of the plexus that pass to the trunk and the first rays of the anterior limb much resemble those of Ruminants; the branch of the serratus magnus is remarkable for its length and size. The median nerve is disposed like that of Solipeds and Ruminants, as far as the carpus; from this point it passes beneath the flexor fons of the phalanges, gives filaments to the interosseous palmar muscles, and at the two rudimentary digits divides into four branches: the two upper are the smallest, and form the collaterals of the rudimentary digits; the inferior two are the longest, and reach the principal interdigital space, forming the collaterals of the two great digits. The ulnar gives off, towards the middle of the arm, a branch that passes to the ulna; at the ulna it furnishes several muscular branches. The nerve then bends round to the outside of the fore-arm, and on arriving above the pisiform bone, bifureates: one branch zoes along the outer border of the flexor tendons, and is continued by the collateral of the external digit; the other is placed on the anterior face of the metacarpus, and ‘also : bifurcates to give the external digits their dorsal collateral nerves, , Caxuntvora.—The four last cervical and first dorsal compose the brachial plexus in the Carnivora; the fifth cervical gives an insignificant filament. When the plexus is un- ravelled, its principal branches are observed to send fibres to each other. _ The number of the distributive branches is the same as in Solipeds, and the dis- position of the superior branches is so analogous as to call for no remark; so we will only describe the anterior brachial, radial, median and cubital nerve. ; The anterior brachial, or musculo-cutaneous, is constituted by a filament from the sixth { cervical and the more voluminous branches coming from the seventh. Placed in front of } the axillary artery, this cord arrives at the scapulo-humeral articulation, where it bifurcates: one of the branches passes forward to the biceps ; the other remains alongside the anterior border of the humeral artery, and terminates by a slightly recurrent branch tht is buried in the anterior brachial muscle, and by a yery fine filament that becomes subcutaneous at the elbow, and descends on the inner border of the fore-arm to be lost in the vicinity of the carpus, The anterior brachial is, therefore, in these animals, a musculo-cutaneous nerve. The branch uniting it to the median nerve is situated a little + arte the middle of the humerus, instead of being beneath the axillary artery, as in he radial nerve, in the Dog, is exclusively formed by the eighth cervical ; it receives filaments from the median, ulnar, and axillary nerve, and gives branches to these three. 766 When it reaches tl.e interstice of the triceps and anterior brachial, it crosses the limb THE NERVES. above the outer face of the elbow, and divides into two series of terminal branches. Fig. 351. NERVES OF THE PALMAR FACE; DOG. A, Trunk of the median dividing into six branches; Bl, Branch of the superficial nervous arch; B2, Branch disappearing on a vessel; B3, B4, Branches uniting with the corresponding ramuscules of the ulnar; B5, Branch forming the internal collateral of the index; 386, Rudimentary branch passing to the thumb; ©, Collateral given off by the median; cl, c2, 3, o4, Colla- terals furnished by the median and ulnar, —a, Palmar branch of the ulnar; b, Super- ficial branch giving off a filament to the hypothenar, and a second that forms the superficial nervous arch; 61, Deep branch passing to the muscles of the skin; m, Not anastomosing with the median; ml, m2, Anastomosing with the corresponding branch of the median; the innermost passes to the muscles of the thumb; ¢, c, c, Collaterals furnished by the ulnar. in the internal and middle lobe of the large cushion of the paw. The muscular branch enters beneath the muscles on the anterior face of the fore- arm. ‘Ihe cutaneous bifureates imme- diately: the smallest branch, passing in- wards, extends beyond the bend the elbow, lies at the inner border of the median subcutaneous vein, «nd is distributed to the _ lower moiety of the fore-arm, the thumb, and interna! border of the index digit. The largest Jies at the outer side of the median subcutaneous vein; it sends a recurrent ramuscule to the bend of the elbow, and, at the elbow, detaches three filaments to the first, second, and third dorsal intermeta- carpal spaces; these filaments bifurcate at the dorsum of the digits to constitute the col- lateral dorsal nerves. The first metacarpal nerve anastomoses, by a fine transverse branch, with the ulnar ramuscule that constitutes the external dorsal collateral of the small digit. To resume : the radial of the Dog gives branches to the dorsal fuce of all the digits, except the external border of the first digit, or auricularis. In the Cut, there are some differences, The internal branch of the radial sometimes lies with the external branch; it is placed at the inner border of the me’ us, gives off a filament to the dorsal face uf the thumb, and «afterwards forms the internal dorsal collateral nerve of the index. The external branch leaves the anterior face of the ca and is situated at the origin of the t ind interosseous space, where it divides info three metacarpal branches; the external of these is very fine, and directed obliquely outwards, anastomosing with the dorsal branch of the ulnar, between the first and second digits, The median of the Dog is united to the ulnar as far as the lower fourth of the arm; it is situated behind the humeral artery, and the filament it receives from the mus- culo-cutaneous joins it at a short distance from the elbow-joint. Placed beside the radial artery, the median is, towards the lower third of the fore-arm, immediatel low the posterior border of the great pal- mar tendon; it afterwards passes through the carpal sheath, giving a branch that constitutes the internal mar of the thumb, and external of the index; it nally forms three branches, the first of which anastomoses with the ulnar, at the surface of the palmar arch, and is lost on an artery; the other two, receiving a fila- ment from the ulnar at the origin of the digits, bifureate to form the internal palmar — collateral of the annularis, and collaterals of — the medius and index. The second gives, in addition, a slender branch, that is lost — In fine, the median of —_— THE BRACHIAL PLEXUS, 767 the Dog furnishes branches to all the digits, except the auricularis and external border of the annularis. In the Cat, the median traverses the — canal at the lower extremity of the umerus, and separates below the carpal arch into three branches. The internal h branch is destined to the rudimentary thumb, and the internal palmar border of the index. The middle branch descends in the third interosseous space, furnishes a filament to the large cushion of the paw, and divides to form the external palmar Fig. 352, collaterals of the index and internal of the medius. Finally, the external branch is placed in the second intermetacarpal space, and gives the following palmar collaterals: the of the medius and internal of the annularis. The ulaar nerve of the Dog, below the elbow, lies beside the ulnar artery to the lower third of that vessel; there it forms two branches—a dorsal and palmar. The dorsal branch becomes subcutaneous, passes along the external border of the fore-arm, metacarpus, and small digit, and con- stitutes the external dorsal collateral nerve of the latter. The palmar branch leaves the carpal sheath, gives off, at the trapezvides, a ramus- cule that passes to the surface of the palmar muscles to form the external collateral pal- mar of the auricularis, and then, at the surface of the deep palmar arch, divides into eight terminal ramuscules. The smallest of these is expended in the rudimentary muscles of tle thumb, the small digit, and interosseous muscles; the largest, three in number, lie on the interosseous arteries, and bifureate at the digits to form the palmar collaterals ; the two internal ramuscules are eo, confounded with the correspond- g branches of the median. From this arrangement, it results that the ulnar nerve supplies the palmar surface of all the digits, the internal ee of the index. V. VERBMOBCKEV se he ulnar of the Cat also divides into “ ‘ a 1 1 and a Imar branch, but the dis- NERVES OF THE PALMAR FACE; CAT. tribution of these is not the same asin the 4, Trunk of the median dividing into two 5 branches; 3B, Internal branch, giving a _. oe branch bifureates at the car- rudimentary filament to the thumb; Bl, ms: one of the filaments forms the external External branch, receiving a filament, f, aad collateral of the small digit; the from the ulnar; ©, c, c, c, Collaterals fur- other reaches the first interosseous sj ace, nished by the median.—a, Palmar branch receives a branch from the radial, and after- °f the ulnar dividing into three branches ; wards gives off the internal dorsal collateral _®, Internal branch, detaching the filament, of the small digit, and external of the f, to the median; 61, External branch ; 62, auricularis. Deep branch; c, c, c, Collaterals furnished The palmar branch does not extend to by the ulnar. all the digits asin the Dog. Passing within the pisiform bone, it divides into several filaments: some of these are distributed to the muscles of the small digit and thumb; another follows the external border of the small digit, and constitutes its external palmar collateral; one of the longest is lodged in the first intermetacarpal space, giving a filament to the large cushion of the paw, and the internal palmar collaterals of the small digit and external of the annularis. COMPARISON OF THE BRACHIAL PLEXUS OF MAN WITH THAT OF ANIMALS. The brachial plexus of Man, like that of the Dog, is constituted by the anterior branches of the four last cervical, and the Jast dorsal nerves. The few variations observed 768 THE NERVES. are very slight, and are to be ascribed to the difference in form of the regions to which the nerves are distributed. ” The shoulder of Man being short, and the other rays of the limb long and well detached, the branches of the brachial plexus can be divided into collateral and terminal, The collateral branches are: 1, The subclavian branch, which is not found in our animals, they having no subclavian muscle; 2, The nerve of the angularis; 3, Nerve of the rhomboideus ; 4, Superseapular nerve ; 5, The serratus magnus (posterior thoracic) — nerve ; 6, Subscapular, which is divided at its origin into two branches as in the Sheep — and Carnivora ; 7, The nerves of the great and small pectorals (anterior thoracic); 8, The Fig. 353, THE NERVES OF THE AXILLA OF MAN, 1, Scalenus medius; 2, Scalenus anticus; 3, Cord formed by 5th and 6th cervical nerves ; 4, Seventh cervical nerve ; 5, Superscapular nerve ; 6, Subclavian artery, cut; 7, Insertion of subclavius; 8, Cord formed by 8th cervical and 1st dorsal nerves ; 9, Pectoralis major, reflected; 10, Internal anterior thoracic nerve; 12, Origin of subclavius; 13, Pectoralis minor, reflected; 14, Internal cutaneous nerve; 15, Axillary artery, cut; 16, Posterior thoracic nerve; 17, Musculo- cutaneous nerve; 18, Origin of pectoralis minor; 19, Median nerve; 20, Nerve of Wrisberg; 21, Coraco-brachialis; 22, Intercosto-humeral nerve; 23, Ulnar nerve; 24, Subscapularis; 25, Brachial artery ; 26, Lateral cutaneous branch of 3rd intercostal nerve; 27, Middle subscapular nerve; 28, Short subscapular nerve; 29, Pectoralis major, cut; 31, Basilic vein; 32, Serratus magnus; 33, Latissimus dorsi. accessory nerve of the internal cutaneous, represented in quadrupeds by the subcutaneous thoracic ; 9, The nerve of the great dorsal ; 10, The nerve of the teres major. The terminal branches go to the arm, fore-arm, and hand. They are: 1. The internal cutaneous, which in the Horse is furnished by the ulnar nerye, It becomes subcutaneous at the upper third of the arm, and a little above the elbow bifur- cates; the anterior is sprrad on the fiont face of the arm to the wrist; the posterior : : : THE BRACHTAL PLEXUS. 769 backwards, and is expended in the skin of back, and inner part of the fore-arm. _ 2. The musculo-cut s or perforans casserii, whose disposition is analogous to that of Carnivora. 8. The azillary nerve, regarding which there is ser og, tet say. 4. radial nerve (musculo-spiral) passes as in animals, lies in the twisted furrow of the humerus, gives off an internal and external cutaneous branch, and reaches the antero-external part of the arm, in the space between the anterior brachial and long supinator, where it terminates by two branches. The anterior of these reaches the back of the hand, and gives off three ramuscules there, which are dis- tributed as follows: the first forms the external dorsal collateral of the thumb; the second bifur- eates, and constitutes the internal dorsal collateral of the thumb and external collateral of the index; lastly, the third supplies the internal collateral of the index and external of the medius. This branch always anastomoses with the dorsal branch of the ulnar. The posterior branch, motor, is expended in the muscles on the posterior and external aspect of the fore-arm. 5. The median nerve commences by two branches : one arises in common with the musculo-cutaneous or anterior brachial, and corresponds to tlie anasto- mosis found around the axillary artery of the Horse; the other is detached from the trunk common to the ulnar and internal cutaneous. The median runs ser, Deas biceps, passes in front of the elbow, and lies beneath the annular ligament of the carpus, where it terminates in furnishing: 1, A filament to the short abductor of tle thumb; 2, Palmar ramus- cules to the thumb, index, and medius, and external border of the annularis. This disposition of the medius, therefore, much resembles that of the Cat. 6. The ulnar nerve passes along the inner border of the arm and fore-arm, and divides, a little above the inferior extremity of the olecranon, into two terminal branches—a dorsal and palmar. The first is directed on the back of the hand, and separates into three metacarpal branches, which, in their course, furnish the dorsal collaterals of the auricularis and annularis, and internal collateral of the medius; the other parts of the hand are supplied by the radial. The second, or palmar branch, is superficial, and detaches the palmar collaterals of the little finger and internal collateral of the annularis, as well as a deep ramuscule that lies across the interosseous muscles, and is a motor nerve. To resume, we see that this distribution of the terminal branches of the brachial plexus of Man much resembles that deseribed in Carnivora, and especially in the Cat. NERVES OF THE FRONT OF FORE- ARM AND HAND OF MAN. 1, Supinator longus, cut; 2, Ulnar nerve; 3, Brachialis anticus; 4, Biceps; 5, Musculo-spiral nerve ; 6, Median nerve; 7, Posterior interosseous nerve; 8, Pronator teres and flexor carpi radialis, cut ; 9, Extensor carpi radialis longior, cut; 10, Brachial artery; 11, Supinator brevis; 12, Flexor sublimis digitorum, cut; 13, 15, Radial nerve; 14, 14, Flexor carpi ulnaris ; 15, Extensor carpi radialis brevior ; 16, Ulnar artery; 17, Radial origin of flexor sublimis digitorum, cut; 18, Flexor pro- fundus digitorum; 19, Tendon of pronator teres; 20, 20, Dorsal branch of ulnar nerve ; 21, 21, Radial artery ; 22, 22, Deep branch of ulnar nerve; 23, Flexor longus pollicis; 24, Abductor minimi digiti; 25, Anterior interosseous nerve; 26, Digital branches of ulnar nerve; 27, Tendon of supinator longus; 28, One of the lumbricales muscles; 29, Pronator quadratus; 31, Tendon of flexor carpi radialis; 33, Digital branches of median nerve; 35, Adductor pollicis. 3D 770 THE NERVES, LUMBO-SACRAL PLEXUS. eee The last two lumbar pairs, and the three first. sacral, in becoming fused, together, form the lumbo-sacral plexus, which corresponds in every respect, — by its constitution, as well as by its mode of distribution, to the plexus of the thoracic limb. It is usual, in human anatomy, to describe a lumbar and a sacral plexus, — each formed by the inferior branches of all the spinal pairs, whose names — they bear. In our opinion, this proceeding has two inconveniences: at first) it separates into two fasciculi the nerves of the abdominal member, and, besides, in including in the des¢ription of these nerves the first lumbar rae a. and the last sacral, elements are introduced in this description which are 3 altogether foreign to it. It may be remarked, that the four first lumbar pairs, when they anastomose with each other, ‘only do so by very slender filaments ; that they only send some subcutaneous filaments to the p limb ; that the two last sacral branches, principally destined to the oe urinary organs and the posterior extremity of the digestive tube, are ordinarily without any direct communication with the others ; that the two last lumbar pairs and the three first sacral are alone fused in the same manner as the brachial plexus, and comport themselves like that plexus in the ainieeeom of their branches, It is with some reason, then, that we have described, in a special manner, the inferior branches of the four lumbar pairs and the two last sacral reserving: the fasciculus formed by the five intermediate pairs for a speci description, under the name of the /umbo-sacral plexus. Mode of constitution.—In glancing at this plexus, we may perceive that it is divided into two portions—an anterior and posterior, each having ‘3 thick trunk in the centre, ‘The first of these trunks is formed by the two above-named lumbar pairs, ; which join each other after a short course, and after receiving an accessory branch from the fourth pair. The second, wider and thinner than the preceding, comprises the fibres of the three sacral pairs which escape from beneath the subsacral vessels, and unite in a single fasciculus. These two trunks are connected with each other by one or two branches pr from the first sacral pair to the obturator nerve—one of the distributive — branches of the first. Relations.—The anterior portion of the lumbo-sacral plexus is conceateliaa beneath the small psoas muscle, and separated by the internal iliac ‘artery from the posterior portion. The latter, placed above and on the side of the pelvis, at the great sciatic opening, corresponds, inwardly, to the subsacral vessels; outwardly, and in front, to the gluteal vessels, e iP Mode of distribution.—The anterior portion of the plexus at first gives off 4 several small branches to the psoas muscle, and particularly to the iliaeus: these branches were designated by Girard the iliaco-muscular nerves; it ' then terminates in two large branches—the crural and obturator nerves. The posterior portion is continued by two important trunks, the great and small | Semoro-popliteal nerves. At the base of the latter, it emits the anterior ‘and 7 posterior gluteal nerves. These branches and their ramifications will be successively studied. : ; Preparation of the lumbo-sacral plexus—After removing the skin and abdomianl viscera, the hind quarters are isolated by sawing through the vertebral column behind | the last rib; then, by means of a section almost in the midile of the pelvis, one ofthe — limbs is ent off, and the pieces, disposed as in figure 355, should be maintained in the ; THE LUMBO-SACRAL PLEXUS. 771 Fig. 355, be ie 5 ae ~~ LUMBO-SACRAL PLEXUS AND INTERNAL NERVES OF THE POSTERIOR LIMB. 1, 1, Lumbo-sacral plexus ; 2, Anterior femoral nerve; 3, Internal saphena nerve ; 4, Obturator nerve ; 5, Originating fasciculus of the great and small femoro-popliteal nerves; 6, Superficial ramuscules of the posterior gluteal nerves; 7, Great femoro-popliteal nerve; 8, Internal pudic nerve; 9, Hamorrhoidal, or anal nerve; 10, Internal plantar nerve; 11, 12, Its digital ramifications. Nors.—In the above figure is seen the posterior of the plexus formed by the nervous branches which pass through the three first subsacral furamina. That which escapes from the foramen between the sacrum and last lumbar vertebra, only gives a fine branch to this part of the plexus, and sends the greater portion of its fibres, in two cords, to the anterior part. This arrangement {s not rare, and is generally seen, we b-liev , when there are only five lumbar vertebre: as is remarked in the Ass and Mule, and sometimes in the Horse. It will, therefore, be understood that the nerve described by us as the first sacral becomes the last lumbar, , 3p2 772 THE NERVES. first position: that is, with the croup resting on the dissecting table near one of the bars, — _ iy limb suspended vertically, the foot upwards, by a cord attached to the ring of e bar. Afterwards, the preparation is executed in two stages. In the first, after the excision of the pelvic organs and the small psoas muscle, the whole of the plexus and its tive branches are dissected, taking figure 355 as a guide, In the second, the posterior part of the plexus, with the nerves it gives off, are exposed on the external side, by excising the greater portion of the principal gluteal muscle and the anterior of the long vastus (abductor magnus, or triceps abductor femoris). as in figure 356. To follow the various divisions of the nerves emanating from the plexus, to their terminations, it is well to use the other limb, which, not being fixed, can be laid ona table, and in this way is more convenient than the first for this part of the operation. 1. Iliaco-muscular Nerves. These nerves are of little importance. The principal one accompanies the iliaco-muscular artery across the substance of the iliacus muscle. 2. Crural or Anterior Femoral Nerve. (Fig. 355, 2.) This is the largest of the branches arising from the anterior portion of the plexus. It descends between the psoas magnus and parvus, to the common conical extremity of the latter muscle and the iliacus, where it is covered by the long adductor of the leg; there it terminates in a wide tuft of branches, destined to the mass of the triceps extensor eruris. _ Below the adductor, it successively emits two long branches, which deserve a particular description. The first represents the nervous fasciculus which, in Man, comprises the crural musculo-cutaneous branches. We have named it the accessory branch of the internal saphena. It reaches the interstice between the two adductors, in crossing the crural vessels very obliquely forward. Leaving this space, it becomes subcutaneous in forming numerous divisions which surround the saphena artery and vein. The second, or internal saphena nerve, passes at first between the long adductor of the leg and the vastus internus, and parallel to the first, which is situated more inwardly and posteriorly. Near the inferior extremity of the interstice separating the two adductors of the leg, it escapes and becomes subcutaneous, dividing into a number of filaments which meet those of the accessory nerve. These two branches communicate by deep or superficial anastomosing loops. Before leaving the space between the adductors, they give some slender filaments to these two muscles, particularly to the anterior. Near their origin, they even distribute some to the iliacus. Becoming sub- cutaneous, their ramuscles cover the inner face of the thigh and leg; the longest of these accompany the saphena vein to the anterior aspect of the — hock. It sometimes, indeed most frequently, happens that the internal saphena nerve and its accessory form only a single branch, whose muscular or cutaneous divisions otherwise comport themselves exactly like the above, This is exemplified in the dissection represented in figure 355, 8. Obturator Nerve. (Fig. 355, 4.) Situated underneath the peritoneum, to the inner side of the iliac vessels which it accompanies to the origin of the obturator artery, this nerve follows the latter to the upper face of the pubis, and passes with it beneath the internal obturator muscle, to traverse the foramen ovale. In this way it : = ee a a THE LUMBO-SACRAL PLEXUS. 773 arrives outside the pelvis, where it nevertheless remains deeply concealed by the muscular masses on the internal aspect of the thigh. Its terminal rami- fications are expended in the obturator externus, the adductors of the thigh, the pectineus, and the short adductor of the leg. The branch destined to the latter muscle is the longest; it leaves the space between the pectineus and the small adductor of the thigh, and descends backwards on the internal face of the muscle to which it is distributed. 4, Small Sciatic or Anterior and Posterior Gluteal Nerves. The small sciatic of the Horse is composed of several cords that issue’ from the pelvis by the upper part of the great ischiatic notch, and which have POSTERIOR PORTION OF THE LUMBO-SACRAL PLEXUS. 1, Conjoining fasciculi of the three first sacral nerves; 2, 3, 4, 5, Anterior gluteal nerves; 6, 6’, 8, Posterior gluteal nerves; 7, 9, Branches which traverse the great sciatic ligament, and communicate between the posterior gluteal branches and the divisions of the internal pudie nerve; 10, 11, 12, 13, Great sciatic nerve and its crural branches; 14, Small femoro-popliteal nerve; 15, Its cutaneous or peroneal-cutaneous branch. been for a long time described as the anterior and posterior gluteal nerves. The anterior gluteal or ilio-muscular nerves (Fig. 356, 2, 3, 4, 5) are four or five in number, and arise either separately or in groups from the posterior portion of the lumbo-sacral plexus. They appear to be more particularly furnished by the two first sacral branches. All leave the pelvie cavity by the great sciatic opening, along with the anterior gluteal vessels. “The 774 THE NERVES. principal branches are lost in the middle gluteal muscle. One of them | (Fig. 356, 4,) crosses the neck of the ilium above the small (or internal) gluteal muscle, and passes outwards to be distributed to the muscle of the fascia lata (tensor vaginw femoris). The last, which is the most slender, descends to the external surface of the gluteus internus, and is distributed in its substance (Fig. 356, 5). bik The posterior gluteal, or ischio-muscular nerves (Fig. 356, 6, 6', 8), are usually two in number—a superior and inferior. The first escapes through the great sacro-ischiatic notch, along with the femoro-popliteal nerves, and is situated on the external surface of the ischiatie ligament. It passes backward, between this ligament and the gluteus medius, to beneath the anterior or croupal portion of the triceps extensor cruris, in which it is distributed by several filaments. Besides these, it gives: 1, In passing beneath the gluteus medins, a slender, but constant filament to the posterior portion of that muscle; 2, Another, and more considerable branch, which bends round the posterior border of that muscle, to be directed forward and outward to the gluteus externus. The second nerve, situated beneath the preceding, appears to be detached from the posterior border of the great sciatic. It is placed at the external surface of the sciatic ligament, is directed backwards in passing below the croupal portion of the triceps cruris, traverses that muscle above the ischial tuberosity, descending underneath the sacral portion of the semitendinosus, soon to leave its deep track and become superficial. It escapes from between the latter muscle and the triceps cruris, aud is lost beneath the skin coverin, the posterior part of the thigh. Its deep portion gives off collate branches which reinforce the divisions of the internal pudie nerve, as well as filaments to the long branch of the semitendinosus muscle. 5. Great Sciatic or Great Femoro-popliteal Nerve, (Figs. 135,13; 357, 1, 2.) This enormous nervous trunk issues by the great sciatic opening in the form of a wide band, which is applied to the external face of the ischiatic ligament. Comprised at first between that ligament and the gluteus medius, it is directed backwards in passing over the fixed insertion of the gluteus internus, and arrives behind the gemini and quadratus femoris muscles. On leaving this point, it is inflected to descend behind the thigh, where it is lodged in the muscular sheath formed for it by the triceps cruris, the semi- tendinosus and membranosus, and the great adductor of the thigh. Arriving towards the superior extremity of the leg, it enters between the two bellies of the gastrocnemii muscles, passes along the posterior aspect of the perforatus muscle, and descends in the channel of the hock, beneath the tibial aponeurosis, following the internal border of the fibrous band that rein- forces the tendon of the hock. It finally terminates at the calcis by two branches; the external and internal plantar nerves. From the point at which the great sciatic enters between the bellies of the gastrocnemii muscles, and as far as the furrow of the calcis, this nerve — corresponds to the branch named in Man the internal popliteal—a branch that is continued by the posterior tibial, which terminates in the plantar filaments. In its long course, this nerve successively emits: 1, The external popliteal nerve ; 2, A branch to the muscles of the deep pelvi-crural region ; 3, Another to the posterior crural muscles; 4, The external saphenous nerye; 5, A voluminous fasciculus to the muscles of the posterior tibial ~ THE LUMBO-SACRAL PLEXUS. 775. region. All these branches will be studied, more especially the external popliteal ; which is so disposed in Solipeds, that Veterinary authorities have deseribed it as a special trunk, by the name of the small femoro-popliteal, and even as the small sciatic nerve. We will afterwards pass to the ter- minal branches. COLLATERAL BRANCHES, 1. Exrernat Sctaric-popLireaL, on SmaLt FEemMoro-popiirean Nerve. — _ This nerve separates from the great sciatic at the gemini muscles of the pelvis. It is then directed forward and downward, proceeds between the triceps cruris and the gastrocnemius muscles, and arrives outside the superior extremity of the leg, behind the lateral ligament of the femoro-tibial articulation, where it terminates by two branches: the musculo-cutaneous, and _ the anterior tibial nerve. In the long course it follows from its origin to its bifurcation, the external sciatic popliteal nerve only furnishes a single collateral branch: this is the cutaneous nerve which is detached from the parent trunk above the gastro- cnemius, and which traverses the inferior extremity of the triceps cruris, to terminate by divergent ramuscles destined to the skin of the leg. It might be named the peroneal-cutaneous branch. Before becoming superficial, this cutaneous nerve gives off a small descending filament which goes to reinforce the external saphenous nerve, after creeping over the aponeurotic layer of the external gastrocnemius. This branch, which might be designated the accessory of the external saphenous, sometimes proceeds diréctly from the popliteal, as may be remarked in Fig..357. _ Terminal Branches These two branches influence the contractility of the muscles belonging to the anterior tibial region, and endow the skin on the anterior face of the foot with sensation. _ The musculo-cutaneous nerve is situated beneath the tibial aponeurosis; it first sends a bundle of ramuscules to the lateral extensor of the phalanges, and continues to descend between that muscle and its congener, the anterior extensor, to the middle of the tibia. It then traverses the fibrous envelope of the tibial muscle, becomes subcutaneous, and gains the anterior face of the metatarsus, where it is lost in the.skin. Some of its terminal filaments may be followed to the fetlock, and even beyond it (Fig. 357, 6). The anterior tibial nerve passes in front of the preceding, to one side of the superior extremity of the leg, and then plunges beneath the anterior ex- _ tensor of the phalanges, giving to that muscle and the flexor of the metatarsus short, but thick, ramuscules. It descends to the front of the tarsus, always covered by the anterior extensor of the phalanges, and placed at the external side of the anterior tibial vessels. When it arrives below the tibia, it lies immediately alongside the pedal artery, and follows it, in its metatursal portion, to near the fetlock. It then separates from its satellite vessel, and on the side of the digit, where it ends by the emission of cutaneous filaments (Fig. 357, 5). Among the ramuscules this nerve abandons in its course, are cited those which carry nervous influence to the pedal muscle. 2. Brancuges to tue Muscies or tHe Deer Petvi-crura Recioxn.— It is known that this region comprises the obturator internus, gemini, and quadratus femoris muscles. The nervous branch sent to them is long and attenuated ; it is detached from the sciatic trunk at the middle of the super- cotyloid ridge, and descends with that trunk behind the coxo-femoral articulation, to distribute its terminal divisions to the above named muscles, 776 THE NERVES. The longest and thickest of these goes to the quadratus femoris. That passing to the obturator internus re-enters the pelvic-cavity by the small ischiatic notch, and ascends to the vicinity of the ilio-sacral articulation. Fig. 357, 8. Branow To THE IscHIO-TIBIAL or Posterior Cruran MuscoiEs.— This branch is thick and short; it arises from the bend formed by the great femoro-popliteal nerve at the gemini muscles, and soon divides into several ramifications which are dis- tributed to the short portion of the triceps cruris, the middle and inferior parts of the semitendinosus, and into filaments destined to the latter muscle pass between it and the great adductor of the thigh, in which they partly terminate (Fig. 356, 12). 4. Exrernat Sapexous Nerve. — This branch commences at from 2 to 6 inches from the point where the great sciatic nerve dips between the gastrocnemii muscles. It is placed on the external gastrocnemius, and descends underneath the special apo- neurotic layer covering that muscle, to the origin of the tendon of the hock. It then receives its accessory nerve—the reinforcing filament which comes from the cutaneous branch of the small femoro-popliteal nerve, and is prolonged beneath the tibial apo- neurosis into the channel of the hock, accompanying the external saphenous vein, and following the external to strengthen the tendo-Achillis, In this way, it occupies the same situa- tion outside the hock that the great EXTERNAL NERVES OF THE POSTERIOR sciatic does on the inner side, It a: afterwards passes over the tarsal 1, 2, pret, —— mari. bs vege phase region, and is expended on the outside : xterna ; 5, An- ° terior tibial nerve re Musculo-cutaneous of the metatarsus in several filaments, nerve; 7, Origin of the peroneal-cutaneous Some of which descend to the outer branch ; 8, Accessory branch of the external aspect of the digit (Figs. 356, 18; saphenous nerve ; 9, External plantar nerve 357, 8). with its divisions, which cover the digital 5. Fascroutt to THE PosTERIoR gs Ae Tistat Muscixes.—This fasciculus is composed of numerous branches, which are detached together from the sciatic nerve on its passage between the gastrocnemii muscles, in the form of a thick short trunk. The muscles of the superficial layer—the cnemii, perforatus, and the thin fleshy band, improperly designated the small plantaris by Veterinarians—receive ramuscules which are remarkable for their the semimembranosus. Some of the — border of the fibrous band that goes THE LUMBO-SACRAL PLEXUS. 7i7 large number and their shortness. Those of the deep layer are supplied by filaments from a single long and thick branch, which descends between the oo. and the internal gastrocnemius. It may be remarked, that the t going to the so-called small plantar muscle, passes underneath the gastrocnemius, outside the perforatus, and that, by its position, it exactly represents the soleus ramuscule of Man. We are, therefore, with Vieq-d’Azyr, Cuvier, and others, justified in naming this little muscle the solearis (soleus), instead of continuing to designate it the small plantaris, which appellation is given to another muscular element. 6. In its course along the tendo-Achillis, the sciatic nerve emits some slender cutaneous filaments, which we do not consider worthy of further notice. TERMINAL BRANCHES, Prantar Nerves (Fig. 355, 10, 12)—These two nerves enter the tarsal sheath, behind the perforans tendon, along with the plantar arteries. Towards the superior extremity of the cannon, they definitively separate from each other; the external is carried outwards between the precited tendon and the rudimentary metatarsal bone ; the internal is placed with that tendon, and follows the posterior border of the inner metatarsal bone. Both afterwards descend on the fetlock, where they comport themselves like the analogous nerves of the anterior limb. DIFFERENTIAL CHARACTERS IN THE LUMBO-SACRAL PLEXUS OF OTHER THAN SOLIPED ANIMALS, As was the case with the brachial plexus, so with this; the differences observed being trifling in the upper part of the limb, but more numerous and important in the region of the foot, the complexity of arrangement varying with the species, Rumiyants.— The lumbo-sacral plexus of these animals is constituted by two lumbar and three sacral nerves, as in Solipeds; but the third sacral ne gives a very fine filament, which reaches the second in passing downward and forward. At the femoro-tibial articulation, the branches of the plexus are similar to those in the Horse. Below that articulation, the following disposition has been observed in The musculo-cutaneous branch of the popliteal is long and thick. It descends on the anterior face of the metatarsus, and at the metatarso-phalangeal articulation bifurcates, the branches forming the dorsal collaterals of the digits. The anterior tibial nerve ts two branches parallel to the tibial vessels; one aloug the metatarsal region, and when it arrives at the bottom of the groove between tle condyles of the metatarsus, it divides into two branches that constitute the dvep collaterals of the digits ; these collaterals furnish filaments to the posterior face of the digital region. The — sciatic resembles that of Solipeds. Its terminal branches, or plantar nerves, differ from those of the Horse in the absence of the transverse anastomosis that unites the two cords in the region of the tendons. * Pig.—The lumbo-sacral plexus of this animal is composed of two lumbar and three sacral nerves: reckoning, of course, as a sacral nerve, the trunk that escapes from between the last lumbar vertebra and the sacrum, The plexus may be divided into two portions, the first furnishing a femor«l and an obturator nerve. The internal saphenous branch of the femoral nerve is long and voluminous; at its origin it is as large as the branch passing to the anterior muscles of the thigh, and it descends on the inner face of the metatarsus, forming the dorsal collateral of the internal digit. The great sciatic is voluminous and round. The branches it gives to the muscles of the pelvis and femur are disposed nearly as in Solipeds and Ruminants; but differences are observed in the external popliteal and the terminal branches. The lo-cut nerve reaches the metatarsal region, where it separates into three branches, which form the dorsal collaterals of the digits. The anterior tibial nerve descends between the two principal metatarsals, and at the root of the middle digits divides to anastomose with the plantar nerves. Of these the external is small, and gives collaterals to the two external digits; the internal, the 778 THE NERVES. largest, descends between the two principal digits, where it bifureates; abové, it gives branch to the internal digit. er Cannivora.—In these animals, the lumbo-sacral plexus is formed by the last four lumbar and the first two sacral, im Tie crural and obturator nerves. which arise from the fourth, fifth, and sixth lumbar nerves, offer nothing particular in their disposition. +5 The internal saphenous branch is as long us in the Pig; it to the internal face of the tarsus, lies alongside the fourth metatarsal bone, aud forms the internal dorsal collateral of the fourth toe. ‘ ee The great sciatic may be described as having, as in Man, two terminal branches — which separate a little above the posterior face of the femoro-tibial articulation. The external popliteal nerve passes to the surface of the external gastrocnemius, enters between the common long flexor of the toes and the long lateral: peroneal muscle, where it bifureates, The lo-cuta branch descends beneath the latter muscle to the lower third of the leg, when it becomes superficial, and, accompanied by a vein, , is lodged in the interspace between that muscle and the anterior tibial : it passesin front of the tarsus, and reaches the spper part of the metatarsus, where it divides into three divisions. It must be mentioned that at the tibio tarsal articulation is thrown off 7. a very fine cord, which is directed outwards, and forms the external dorsal cullater: c é of the first toe. Exch of its three terminal branches courses along an intermetat: cs. space, and at the metatarso-phalangeal articulations separates into two eres ~4 whence results the following distribution: the external branch forms the intern ee dorsal collatera's of the first toe and external of the second; the middle cues 2 1g, 6 Pia Mie A a the interns] dorsal collaterals of the second toe and external of the third; last! internal furnishes the internal dorsal collaterals of the third toe and external of the fourth. The anterior tibial nerve accompanies the artery of that name, descends along the external face of the tibia, and terminutes in two branches at the tarsus. Of these, one is distributed to the tarsal articulations and the pedal muscle; the other, internal, enters the intermetatarsal space, and at the corresponding metaturso-phalangeal joints _ anastomoses with the internal branch of the musculo-cutaneous nerve, and is lost inthe same parts. The internal popliteus forms the second terminal branch of the great sciatic nerve, and in the Dog and Cat represents that portion of the latter whicl:, in the Horse, is situated behind the femoro-tibial articulation. It is continued by the posterior tibial nerve, Which terminates by the two plantar nerves. During its course, the external popliteal furnishes articular and muscular filaments, as well as cutaneous twigs — subsequently; among the latter may be mentioned the external saphenous, which arises by two branches, and is expended behind the malleolus, at the outer side of the tarsus. The plantar nerves are external and internal; the latter lies at the inner border of the — tendon of the superficial flexor muscles of the phalanges, and when it joins the middle of the metatarsus, it detaches a fine filament that forms the internal plantar collateral of the fourth toe; it then passes obliquely towards the first toe, at the deep face of the above-named tendon, and successively pives off three filament-—one for each inter- metatarsal space. These filaments anastomose with the terminal branches of the — external plantar, at tle metatarso-phalangeal articulations; the first two filaments supply the large cushion of the paw. 2 t The external plantar nerve passes between the two flexor tendons of the toes, where it gives a filament that constitutes tlie external plantar collateral of the first toe. Itis afterwards placed outside the deep flexor, then enters beneath the short flexor and — divides into several branches, muscular and digital. Each of the latter, three in number, passes into a corresponding iterosseous s and bifureates at the metutarso- phalangeal articulations, receiving filaments from the internal plantar, aud forming the following plautar collat: rails: the internal of the first toe, internal and external of the second, internal and external of tle third, and external of the fourth digit. : COMPARISON OF THE LUMBO-SACRAL PLEXUS OF MAN WITH THAT OF ANIMALS, It is usual, in human anatomy, to describe a lumbar and a sacral plexus. e" The lumbar plexus is constituted by the ansstomoses of the anterior branches of the five lumbar nerves;' these are united by fine filaments, which sre not intricately associated. The divisions of this plexus are distinguished as collateral and terminal — branches. The first, destined to the upper part of the limb and the skin covering the () Wilson says the four upper lumbar nerves and the last dorsal; Heath gives the sane constitution.) SF § ; ia: a - “FS THE LUMBO-SACRAL PLEXUS, 779. external genital organs, are represented in Solipeds by the ramifications of the lumbar nerves, which have been. separately describe, The terminal branches are the obturator crural, and anterior femvral (or anterior crural), There is nothing to be said respecting the obturator nerve ; it leaves the pelvis by the obtura- Fig. 358. tor foramen, asin all the animals mentioned. The crural has been described as having four terminal branches: the internal and external musculo-cutaneous, the nerve of the triceps crureus (musewar branch), and the in- ternal saphenous, The two mus- culo-cutaneous branches laye their analogue in the Horse, in the filament we have named the accessory branch of the internal saphenous. The nerve of tlic triceps is expended in the an- terior rectus, and the yastus internus and externus. The saphenous de-cends between the muscles of the inner aspect of the thigh, beneath the aponeu- rosis, and becomes superficial at a short distince from the con- dyle of the femur, giving a patellar branch that divides in the skin of the knee, and a tibial branch that is expended on the inner face of the tarsal articulations and the foot. The sacral plexus comprises the first three sacral nerves, t» which is added a lumbo-sacral branch furnished by the lumbar nerves, and a fine tilament that LUMBAR PLEXUS OF MAN, ascends from the fourth sacral. 1, Right. gangliated cord of sympathetic; 2, Abdominal Ten collaterals and a ter- aorta; 3, 3, Last dorsal nerves; 4, Psoas parvus; 5, minal branch arise from this Quadratus lumborum; 6, Psoas magnus; 7, 7, Ilio- plexus. hypogastric nerves; 8, lliacus internus; 9, 9, Ilio- The collateral branches are inguinal nerve; 10, Lumbo-sacral nerve; 11, Genito- divided into intrapelyic and crural nerve; 12, Gluteal nerve; 13, Iliac branch of extrapelvic: they are five in ilio-hypogastric nerve; 14, Sacral plexus; 15, 15, 15, euch group. The first are des- ‘External cutaneous nerves; 17, Transversalis abdomi- tined to the muscles of the inner nis; 19, Obliquus internas; 21, Obliquus externus; aspect of the pelvis, and to those 23, 23, Anterior crural nerves; 25, 25, Obturator of the perineum and the skin nerves ; 27, 27, Crural branch of genito-crural nerve ; of this region. The second are 29, Genital branch of genito-crural nerve; 31, Extertal distributed to the muscles on iliac artery ; 33, External abdominal ring. the outer aspect of the pelvis, and the skin on the posterior face of the thigh, They are: 1. Visceral branches that descend on the sides of the rectum and are lost in the hypogastrie plexus ; 2, Nerve of the elevator of the anus; 3, Hamorrhoidal or anal nerve ; 4, Nerve of the internal obturator that appears to arise, in the Horse, from the sciatic trunk; 5, Internal pudir, which h»s been described with the sacral nerves. Im Man this nerve leaves the pelvis by the grcat sciatic notch (or foramen), and returns to it by the lesser; within the ischiatic tuberosity it divides into two branches: an inferior or perineal, and a superioy or dorsalis penis nerve. The latter is placed on the dorsum of the penis, and reaches the mucous membrane of the glans and prepuce; the former dees not go beyond tle muscles and integuments of the perineum, 6, The superior gluteal nerve ; 7, Nerve of the pyramidalis ; 8, Nerve of the superior gemellus ; 9, Nerve of the inferior gemellus and quadratus cruralis ; 10, The small sciatic, or inferior gluteal nerve, the inferior or femoral branch of which is very long, descending, as it does, to the middle of the posterior face of the thigh, beneatir the crural apoueurosis, to the popliteal space, where it becomes superficial, and terminates in the skin of the upper portion of the be. ~ NERVES AT THE POSTERIOR ASPECT OF HUMAN LEG. Popliteal artery; 2, Great sciatic nerve ; 5, Adductor magnus ; 4, Biceps; 5, Superior internal articular artery; 6, External pop- liteal nerve; 7, Gastrocnemius, cut; 8, Anterior tibial artery; 9, Tendon of semi- membranosus; 10, Peroneus longus; 11, Sural arteries and nerves; 12, Peroneal artery; 13, Internal popliteal nerve; 14, Tibialis posticus; 15, Portion of soleus ; 16, Peroneus brevis; 17, Popliteus; 18, Flexor longus pollicis; 19, Posterior tibial nerve; 20, Calcanean branch of posterior tibial nerve; 21, Posterior tibial artery ; 22, Tendo-Achillis ; 23, Flexor longus digit- orum; 25, Tendon of tibialis posticus; 27, Plantar nerves; 29, Plantar arteries. THE NERVES. Fig. 360, E 3 6 NERVES AT THE FRONT ASPECT OF HUMAN LEG, 1, External popliteal nerve; 2, Anterior tibial artery ; 3, Musculo-cutaneous nerve ; 4, Anterior tibial nerve; 5, Peroneus longus; 6, Tibialis anticus; 7, Extensor longus digitorum; 8, Anterior annular ligament ; 9, Peroneus brevis; 10, Tendon of extensor proprius pollicis; 11, Extensor proprius pollicis; 12, Dorsal artery of foot ; 13, Point at which the musculo-cutaneous nerve pierces the fascia and bifurcates; 14, Tendon of tibialis anticus; 15, Internal branch of musculo-cutaneous nerve; 16, Cutaneous branch of anterior tibial nerve; 17, External branch of musculo-cutaneous nerve; 19, Deep branch of anterior tibial nerve ; 21, External saphenous nerve; 23, Extensor brevis digitorum. — pas a THE GREAT SYMPATHETIC NERVOUS SYSTEM. 781 The terminal branch of the sacral plexus forms the t sciatic nerve, whose distribution is the same as that of Carnivora. The collateral ramuscules of the great sciutic are the branch of the long portion of the biceps; the semitendinosus and semimembranosus branch; the braneh to the great adductor; and, lastly, that to the short portion of the biceps. It terminates by the external and internal popliteal. The musculo-cutaneous and anterior tibial, continuations of the external poplitens, com themselves almost the same as in the Dog. They form dorsal collaterals to the fourth, and fifth toes, as well as to the second. The internal popliteal presents an external saphenous nerve that passes along the external border of the foot, and has, in addition, a branch that ascends on the dorsum of that orgim. The external saphenous furnishes the dorsal collaterals to the first toe, and the external colluteral to the second. The posterior tibial nerve continues the internal sciatic in the leg; it terminates in the plantar nerves. The internal plantar furnishes the collateral nerves to the fifth, fourth, and third toes, and the internal collateral of the second toe, The external divides into three branches: the two superficiul branches fourm the collaterals of the first toe, and the external collateral of tle second; the deep branch passes inwards, behind the interosseous muscles, and is expended in those of the fourth space, after giving filaments to the oblique ab:luctor of the large toe, transverse abductor, last two lumbricales, to the interosseous, aud very fine filaments to the articulations of the tarsus with the metatarsus, It will therefore be seen that, in Man, the branches of the deep trunk of the external plantur join those of the internal plantar, to form the collateral nerves. CHAPTER III. THE GREAT SYMPATHETIC NERVOUS SYSTEM. PREPARATION oF THE Great SyMPATHETIC.—The same subject ought to suffice for the ion of this, us well as the pneumogastric and spinal nerves. After placing the animal in the first position, the intestines are removed, one of the posterior limbs cut off, and the greater om of the os innominatum cleared away by sawing through the eyes mbis and the neck of the ilium; the dissection of all the abdomino-pelvic a on of the system, and that of tle terminal branches of the pneumogastric nerve, is en proceeded w.th. The anterior limb of the same side shoul! be afterwards detached, tlie scapula having been previously sawn across its middle part, and the thorax thrown open by the ablation of the entire costal wall, in sawing through the sternal cartilages below, and the ribs above, at their superior extremity All the thoracic portion of the glionic nervous apparatus, and the pneumogastric nerves may then be prepared. Nothing more remains to be accomplished except the dissection of the sympathetic and the vagus nerve in the cervico-cephalic region, with that of the spinal nerve; this operation is not attended with any difficulty, and should be preceded by the extirpxtion of a branch of the inferior maxilla, It is useful to inject the arteries previously ; as then the filaments of the sympathetic that lie alongside the vessels of the different organs in the abdominal eay:ty can be more easily followed. r The great sympathetic, also named the trisplanchnic system (or\avyxvov —an intestine or viscus ), because of its position and destination, is the nervous apparatus of the organs of vegetative life. - As has been already shown in the general consideration of the nerves and the whole nervous system, this apparatus has for its base two long cords extending from the head to tho tail, underneath the vertebral column, and to the right and left of the median line. Towards the last sacral vertebra, a portion of these two cords converge towards each other, and lie beside the median coccygeal artery. Some anatomists think that the great sympa- thetic does not stop at this point, but is prolonged beneath the coccygeal vertebre, where it enters a ganglion that has been described of late years as the “coccygeal gland,” and whose nature has been very much contested. Each cord presents on its course numerous ganglia, to whose presence it WE NERVES. 782 owes its chain-like aspect ; they are usually elliptical in sha , though they t may also be round or semiluuar ; in all cases they are studded with Behe. tions at their borders. Beneath cach of the regions of the spine they are eq in number to the vertebrae, with the exception of the cervical region, in which are only two—one at the top, the other at the bottom, of the neck. . To this chain arrive afferent branches, by the union of which it is con- stituted ; these branches are furnished by the nerves of the medulla oblongata and the inferior spinal branches, except those of the coccygeal region, The — - afferent branches join the sympathetic at each ganglion; but as there are only two ganglia in the region of the neck, the afferent filaments of the cervical neryes are grouped i in such a manner as to reach the quperior and inferior ganglion. Those nerves which are given off from the ganglia to be distedbuited tbo the viscera, are named the efferent or emergent branches. They are interlaced around the arteries to reach their destination, forming plexuses on the surface of these vessels. This general idea of the disposition of the great sympathetic is sufficient to show that its double ganglionic chain does not represent two particular nerves arising at one determinate point, and ending at another. Properly speaking, they have neither origin nor termination; they are always giving off branches which are as frequently replaced by others: in this way they might be compared, in this respect, to the median spinal artery, which offers somewhat the same mode of constitution—with its afferents supplied by the spinal branches from the intervertebral foramina, and its efferents destined to the substance of the spinal medulla. Srrvcturrt.—The ganglia of the great soley ae differ but little in their structure from the spinal gan whose constitution has been already made known. ‘then have an envelope of connective tissue, which sends aa fine septa into their interior. In the spaces are cells a little smaller and paler than those of the spinal gan- glia; they are round, or furnished with poles that bring them into communication with the afferent and efferent nerve-tubes ; there are also, in the ganglia, tubes which only pass through it, and merely lie beside the cells. Fig. 361. SYMPATHETIC GAN- GLION FROM A a, 4, PUPPY. Trunk of the sympathetic nerve; b, Communicating branches from a spinal nerve; these divide into two fas- eiculi which pass upwards and down- wards in the trunk; c, ¢, The ganglion com of gan- glion cells; d, Small branch, _ probably destined to accom- pany an artery; ¢, isceral branch. The afferent branches of the ganglia have the white tint of the cerebro-spinal nerves, and are named the grey nerves. They owe their colour to the fibres of Remak, which they contain in large quantity. With these nucleated fibres are associated fine nerve-fibres, and double-contoured fibres which proceed from the com- municating rami, or afferent filaments supplied by the spinal nerves ; these fibres often leave the ganglia to pass directly to organs. In describing the sympathetic chain, it is divided into — j five sections: a cephalic, cervical, dorsal, lumbar, and sacral, 1. Cephalic Portion of the Sympathetic. This is composed of the spheno-palatine, ophthalmic, and otic ganglia, all of which communicate with the superior cervical - , inosculating to form a terminal ' plexus, of which the ultimate ramifications pass into the papilla, c, c, c. Epwermis.—The epidermis is a thin pel- a... Ce licle, covering the superficial face of the geuries SDR wey derma; it is destitute of nerves and blood- vessels, and is formed hee ——— are being continually deposited on the corium ; these cells become fisttened in layers as they ihe tan nice ts are up from the latter, and are des- gland,-and uniting in two ex- troyed by friction on the surface of the skin, cretory ducts, 6, 6, which join The deep face of the epidermis is moulded into one spiral canal that per- on the upper surface of the derma; con- aghge sar ineg aes sequently, it lodges the papillw, and dips into gland jis imbedded in fat’ vesi- the follicles and excretory ducts of the glands cles, ¢, e. of the skin; its external face is not a very exact repetition of the surface of the derma, and is covered with hair. The epidermis tends to equalise, and to fill up, the depressions existing between the papille. SUDORIPAROUS GLAND, MAGNIFIED 796 THE APPARATUS OF THE SENSES. Srrvucture.—The epidermis comprises two layers, which are not distinct from each other in the Horse. The deep layer, or rete composed of soft, nucleated, pigmentary cells, which are round on the surface of the derma, and polyhedric elsewhere. The superficial, or horny layer, is a constituted by hard, horny, flattened cells, which still contain some pigment- granules, and are insensibly confounded with those of the rete mucosum. (The theory of growth of the epidermis is believed to be as follows :—a layer of plastic lymph is thrown out on the surface of the derma, and is converted into granules, which are termed cell-germs, or cytoblasts. These — imbibe serum from the lymph and adjacent tissues, so that the outermost covering of the cytoblast is gradually distended ; the latter becomes a cell, and its solid portion, which always remains adherent to some point of the inner surface of the cell membrane, forms the nucleus of the cell. Within this nucleus one or more nuclei are developed; these are named nucleoli. The process of imbibition continuing, the cell becomes more or less spherical ; so that, after a certain time, the papillary layer of the derma is covered by a thin stratum of spherical cells pressed closely together, and cornea with every irregularity of the papillew. New cells being continually produced — before the formation of the others has been quite completed, these are removed in layers further and further from the surface of the derma, and becoming subjected to the influence of physical laws, their fluid contents evaporate : they collapse, flatten, and gradually assume an elliptical shape; then they are a mass of completely flat cells, with an included nucleolated nucleus, and finally become a thin mem- branous scale, in which the nucleus is scarcely appa- rent). , In Solipeds and other animals, the epidermis is generally dark-coloured, from the presence of pig- ment corpuscles, the number of which increases with their depth in the membrane. This coloration is intended to prevent the rubefacient effects of the heat of the sun’s rays, by augmenting the absorb- ing and dispersing power of the cutaneous In the majority of cases, this coloration is absent in the Sheep, whose skin is protected by a thick fleece ; and also in the Pig, whose habits in the wild, as in a domesticated condition, keep it out of the direct action of the sun. : ; (In some regions of the body of all animals, the Fig. 369. OBLIQUE SECTION OF EPI- DERMIS, SHOWING THE PROGRESSIVE DEVELOP- = § MENT OF ITS COMPO- \ NENT CELLS, a, Nuclei resting upon the surface of the derma, f ; these nuclei are gradu- ally developed into cells at 6, c, and d, and the cells are flattened into lamella, forming the outer surface of the epi- _ dermis, e. (The functions of the skin are, as we have seen, tactile and secretory ; in y ‘ addition, it is eminently protective. Its secretory action is always more or skin forms folds, as at the junction of the fore-limb with the body, the flank, and between the thighs. In the Cow, it forms the large pendulous layer at the throat and breast, known as the “‘ dewlap ;” and in the Goat and Pig, it not unfrequently constitutes teat-like prolongations depending from the throat, 4 which nearly always contain a small cartilagi nucleus and some muscular fasciculi. The thickness of the epidermis is sometimes greatly increased by wear and friction, as we frequently see in the skin covering the knees of Sheep, ete. less active, but the production of perspiration is greatest when the body is " “ ra! * . ,. = 4 ai THE INTEGUMENTARY APPENDAGES. 797 at a high temperature, as during active exertion ; at other times the perspira- tion is insensible. In this respect, the skin has intimate sympathetic relations with other organs which have somewhat analogous functions, such as the lungs, kidneys, intestines, etc., and when its function is disordered or checked, it induces alterations in the secretions of one or all of these organs. The skin is also the seat of a constant and important respiratory action, as it absorbs oxygen and throws off carbonic acid, and any interruption to this process is injurious.) _Articte II.—Appenpacres or THE SKIN. The appendages of the skin are hairs and horny productions, dependents of the epidermic layer. HAIRS. The hairs are the filaments which, collectively, form the external covering of the skins of animals. In the Horse, the bristly appendages known as horse-hair should be distinguished from the hair proper; the latter are fine and short, particularly in the regions where the skin is thin, imbricated on each other, and spread over the entire surface of the body in a continuous layer which is designated the coat; the former are long and flowing, occupy the summit of the head, where they constitute the forelock, the upper border of the neck, where they form the mane, and cover the caudal appendage with a splendid tuft, the tail. Some of these also form special organs on the free margin of the eyelids, and are termed eyelashes ; while others inserted about the lips and below the eyes, are named tentacula. (The eyelashes are chiefly implanted in the upper lid. The hairs of the tail are the longest and strongest in the body. ‘These particular hairs also grow on the posterior aspect of the limbs, generally from about the knees and hocks to the hoofs; at the sesamoid bones they constitute a long tuft, the fetlock, which surrounds the horny growth named the “ergot.” These “ foot-locks” are peculiar to the Horse, and vary in length and coarseness with the breed of the animal.) When the hair is fine, long, and wavy, it forms wool ; and when straight and rigid, as in the Pig, it is known as bristles. In the Ass and Mule, the forelock and mane are rudimentary or absent, and the hair of the tail is limited to a small tuft at the extremity of the organ in the former animal, while in the latter it is much less abundant than in the Horse. _ In the Ox, these hairs are not present, except at the extremity of the tail, as with the Ass. There are scarcely any other animals which have other hairs than those composing the coat. (The ordinary hair of the coat is soft and elastic, inclined in particular directions, and varies in length not only according to the regions of the body on which it grows, but also according to the season or climate. In the Horse, the direction of the hair of the coat gives rise to curiously-formed waves, lines, and circles, the most constant of which is on the forehead. In the Cow, the hair is frizzly on the forehead ; on the posterior part of the thighs it has a particular direction, while on the outer side it passes downwards, and from the posterior part of the mamma it ascends as high as the vulva; this characteristic disposition forms what the French have termed écussons, by which some have pretended to recognise the lactiferous qualities of the animal. 798 THE APPARATUS OF THE SENSES. ‘In the Sheep, real hair, not wool, is found on the lower part of the face, and the extremities of the limbs. ae In the Goat, the hairs of the beard are very long, and compose a dis- — tinctive tuft; this animal has also a fine crisp duvet or down beneath the ordinary hair. a. In the Pig, the bristles are very strong in the region of the back: in old animals they are usually bi- or trifurcated at their free extremity ; there also exists a fine soft hair on this animal. It has no tentacular hairs. In the Dog, the length, fineness, and consistency of the hair depends on the breed. . In the Cat, the hair, in some breeds, as in the Angora, is remarkable for its length and softness. This creature has the tentacula enormously developed as a moustache. , : In none of these animals is there a “ foot-lock.”) Srrvoture.—The hairs are implanted in the texture of the derma, and sometimes even in the subjacent tissues, their base being enclosed in a follicle, at the bottom of which their elements are developed. It is therefore necessary to study: 1, The structure of the hair; 2, That of the hair-— follicle. 1. The hair presents a free portion, the shaft, and another concealed in the follicle, the root ; the latter widens at its base—the bulb of the hair—to embrace the papilla or hair-germ. Three superposed layers compose a hair. The epidermis is a thin lamella of horny flattened cells, imbrivated like tiles on a roof. Its elements are marked on the surface of the hair by shaded lines anastomosing to form a network ; they enlarge, and become more apparent under the influence of an alkali. The epidermis belongs to the shaft and a portion of the root ; near the bulb it is replaced by soft nucleated cells, which are implanted vertically. | The cortical substance forms the largest part of the thickness of the hair. It is striped longitudinally, and provided with pigment granules, whose number varies with the colour of the coat. In white hairs these granulations are absent, but there are found-in them, as well as in coloured hairs, small spaces containing air, and which exhibit a dark colour under the microscope. Treated by potass or sulphuric acid, the cortical substance is reduced to elongated spindles, which again may be decomposed into epithelial lamella— narrow, and with nuclei. On arriving at the root, the cells change their character, becoming polyhedric, filled with fluid, and exhibiting a perfectly distinct nucleus and more or less pigment. The medullary substance occupies a narrow irregular cavity in the centre of the hair, extending from the bulb or termination of the root, to the point. It has for its base rectangular, rarely circular, cells, which, according to Kélliker, contain fat granulations and air globules. . 2. The hair-follicle is a narrow cavity, slightly contracted at its orifice and dilated at the bottom, where the hair papilla is placed. It is a simple involution of the skin, as its structure demonstrates. It presents, externally, a loose conjunctival layer, analogous to the reticular layer of the derma ; next, an internal dermic layer, dense and close like the papillary layer of the skin ; an amorphous limiting membrane; an epidermic zone, the external sheath of the hair, formed by cells, similar to those of the rete mucosum ; and a second epidermic zone, the internal sheath of the hair, which repeats the horny layer of the epidermis, and is confounded with the termination of the epidermis of the hair towards the lower third of the follicle. The papilla or hair-germ, is a small, conical, vascular, and neryous THE INTEGUMENTARY APPENDAGES. - 799 prolongation rising up into the hair-bulb. It furnishes the hair with nutrition and the elements of growth. The walls of the follicles of the large hairs, or tentacula, which garnish the lips of the Horse, or bristle from those of the Cat, are provided with nervous ramifications which endow these with a high degree of sensibility, and enable them to play an t in the exercise of touch. Two glands, and a smooth muscular fasciculus, are annexed to the pilous follicle. The sebaceous glands, which have been already described, into the sheath of the hair by a small excretory canal, which traverses the fibrillous walls of the follicle. The muscular fasciculus is situated on the side to which the hair and its follicle are inclined ; it arises from the face of the derma, and terminates at the bottom of the follicle, which it erects by contracting. When the fasciculi contract over a wide surface, the extent of the skin is diminished, and the hairs are erected and partially ejected from their follicles (producing the cutis anserina). (The formation of a hair is identical with the formation of the epidermis by the papillary layer of the derma. The capillary plexus of the follicle throws out plastic lymph which is converted into granules, then into cells which become elongated into fibres. The cells that are to form the surface of the hair, are converted into flat scales that inclose the fibrous structure of the interior. As these are successively produced, they overlap those pre- viously formed, and give rise to the waving lines seen on the circumference of the hair; this overlapping also causes the roughness experienced in drawing a hair between the fingers from its point to the bulb. The latter is the newly-formed part of the hair, its expanded form being due to the greater bulk of the fresh-cells. The colour of the hair is very varied in animals, ranging from black to white, red and brown, with all the intervening shades. The tint also changes at different periods of life, being sometimes altogether altered between the juvenile and adult periods; dark-coloured Horses becoming ___ light-coloured as age advances. Besides, it is never uniform in the same animal ; black Horses not unfrequently having white patches and diverse tints, with other dissimilarities. The disease termed “melanosis” is very common in old white Horses which were previously grey, and is supposed to be due to the localization of the black pigment at certain limited points. The hair grows according to the climate, seasons, food, etc., and varies with the species and breed. The coat in every animal i is shed at certain times, and is replaced by new hairs. The hair preserves the skin from unhealthy external influences—wet and cold for example. It is a bad conductor of heat, and therefore keeps the body warm. ‘The tentacula are very useful as tactile organs ; while the mane, forclock, and tail keep away insects, and the long hairs of ‘the fetlock and pastern protect these parts the injurious effects of cold and wet, and the action of foreign bodies.) HORNY PRODUCTIONS, __ (Preparation.—The hoof and its contents may be examined by sections made in different directions. The hoof can be removed by prolonged maceration, or by roasting on a fire, when it may be cut and torn off by means of the farrier’s knife and pincers. ) The horny tissues form several groups: the first comprises the horns of Ruminants; the second, the so-called chesnuts of Solipeds; the third, the protective layer enveloping the digital extremities, and constituting the claws of Carnivora, the Pig, Ox, Sheep, and Goat, and the hoofs of the Horse, Ass, 800 THE APPARATUS OF THE SENSES. and Mule. These latter productions, ranking as they do among the most important organs of the locomotory apparatus of Solipeds, will first receive - notice. 1. The Hoof of Solipeds. The hoof of Solipeds is an extremely important study, because of the numerous diseases which affect this region. Consequently, it has been the subject of several voluminous works, to which the student must be referred for a more complete description of its organisation ;' as we cannot do more here than give some essentially descriptive details, necessary to fill up the 2 outline that we have traced out. : : , We will at first glance at the parts contained in the hoof, returning afterwards to a description of the horny case itself. Fig. 370. a. The Parts Contained in the Hoof. Proceeding from within to without, we find, in the interior of the horny box: 1, The third phalanx, navicular bone, and lower part of the second phalanx, forming the articula- tion of the foot; 2, The four ligaments that bind this artieu- lation; 38, The tendon of the common extensor of the pha- langes which covers the articu- lation in front, and that of the perforans which supports it behind, in becoming inserted into the pedal bone, after gli over the posterior surface the navicular bone; Oe complementary apparatus of the third phalanx; 5, The matrix of the hoof, or keratogenous membrane—a continuation of 1, Anterior extensor of the phalanges, or extensor tho derma covering the digital pedis; 2, Lateral extensor, or extensor suffraginis ; ° 3, Capsule of metacarpo-phalangeal articulation; T8100. To these parts must 4, Large metacarpal bone; 5, Superficial flexor of be added the vessels and nerves, the phalanges, or perforatus; 6, Deep flexor, or The description of the bones perforans; 7, Sheath; 8, Bursa; 9, Sesamoid iven at 84 bone ; 10, Ergot and fatty cushion of fetlock; 11, oy been siabeerh gid o.oo Nia 85, Crucial ligament; 12, Short sesamoid ligament ; ? ° . : 13, First phalanx ; 14, Bursa; 15, Second pha- Of tho articulation and its Janx; 16, Navicular bone; 17, Plantar cushion; ligaments, at pages 157, 158 ; 18, Third phalanx; 19, Plantar surface of hoof; Of the tendon of the an- 20, Sensitive or keratogenous membrane of third terior extensor of the phalanges, halanx. spd at page 263 ; . LONGITUDINAL MEDIAN SECTION OF THE FOOT. Of the perforans tendon, at page 286 ; Of the arteries, at pages 553, 554, 555 ; ! See particularly, among the most recent and complete French works, the ‘ Traité de l’Organisation du Pied du Cheval,’ by M. H. Bouley. (See also the still more recent. work by Leisering, ‘ Der Futz des Pferdes,’ Dresden, 1870. Also a long series of papers by me on this subject in the ‘ Veterinarian’ for 1871-2.) _— «= —s THE INTEGUMENTARY APPENDAGES. 801 Of the veins, at pages 612 to 616; o the nerves, at pages 762, 763. t remains to notice the complementary apparatus of the third phalanza, and the keratogenous membrane. Tentre ’ _— A. Comprementary Apparatus or THe Pepat Bons.—In the indication we gave of this apparatus at page 85, we said that it was composed of two - lateral pieces—the fibro-cartilages, united behind and below by the plantar eushion : a fibrous, elastic mass, on which the navicular bone r-sts, through the medium of the perforans tendon. We will take this distinction as the basis of our study. 1. Frero-cartinacrs or tHE Pepa Bonr.—Each of these pieces re- presents a plate flattened on both sides, having the form of an oblique-angled parallelogram, and prolonged behind the third phalanx. The ezternal face is convex, and pierced with openings for the passage of veins; it slightly overhangs that of the pedal bone. The internal face is concave, channeled by vascular furrows, and covers, in front, the pedal articulation, and the synovial cul-de-sac which projects between the two lateral ligaments of that joint ; below and behind, it is united to the plantar cushion, either through continuity of tissue, as at the in- ferior border, or by fibrous bands passing - from one to the other. The upper border, Sometimes convex, sometimes rectilinear, is thin and bevelled like a shell; it is separated from the posterior margin by an obtuse angle, in front of which this border is often broken by a deep notch that gives passage to the vessels and nerves of the digital por- tion. The inferior border is attached, in front, to the basilar and retrossal processes ; behind the latter, it is reflected inwards to become continuous with the tissue on the lower face of the plantar cushion. The posterior border is oblique from before to behind, and above to below, and joins the preceding two. The anterior border is oblique in the same direction, and is united) = ORIZONTAL SECTION OF THE so intimately with the anterior lateral liga- Rene eae ment of the pedal articulation, that it cannot 1 Front, ov toe of the pig bl Mans be separated from it except by an artifice Insertion of the extensor pedis; 5, of dissection. It sends to this ligament,and 0s pedis; 6, Navicular bone; 7, to the tendon of the anterior extensor of inet i of “ rie as sag the phalanges, a fibrous expansion that be- CaP 388; ©; *lexor pedis tendon ; Elta Posed with that of the opposite’ tile. Pike oak ce tae te he The fibro-cartilages comprise in their frog. aed : structure a mixture of fibrous and cartilagi- ‘nous tissue, though the mixture of these is far from being perfectly homo- geneous, or everywhere in the same proportions. | The cartilages of the fore-feet are thicker and more extensive than those of the hind-ones. (The lateral fibro-cartilages are peculiar to Solipeds.) 2. Prantar Cusnion.—The plantar cushion is a kind of wedge, situated in the space between the two cartilaginous plates of the third phalanx, and between the perforans tendon and the lower part of the horny box. : Its shape F Fig. 371. 802 THE APPARATUS OF THE SENSES. allows it to be considered as having an antero-superior and an infero-posterior Jace, a base, summit, and two lateral borders. The antero-superior face is moulded on the aponeurotic expansion of the perforans tendon, and is “ covered by a cellulo-fibrous membrane, the pene tunic of the plantar cushion, which is continuous, on its inner face, with fibrous septa by which this organ is traversed, and adheres by its external or anterior face to the reinforcing sheath interposed between it and the perforans tendon.”—Bouley. This expansion is prolonged, above, to the fetlock, where it is confounded with the superficial fascia of the meta-— carpal region; it is margined, laterally. by two Fig. 372. small, very strong ligamentous bands which, at their middle portion, cross, in a» very oblique a manner, the fasciculus formed by the vessels and \ | nerves of the digit. Each of these bands is fixed, | superiorly, to the base of the rudimen igi known as the ergot, and to the knob of the lateral metacarpal bone; their inferior extremity is at- tached within the retrossal process. ’ The infero-posterior face of the cushion is covered by the keratogenous membrane, and pre- sents at its middle the pyramidal body, a promi- nence exactly like that of the frog, to which it corresponds. It shows, then, in front, a single conical prolongation, and behind, two divergent prominences separated by a median excavation. The base of the apparatus lies behind, and is inclined upwards; it is divided by a depression into two lateral masses—the bulbs of the plantar cushion—on the inside of which the posterior prominences of the pyramidal body reach, and LOWER FACE OF THE Horsk’s Which become confounded, outwardly, with the FOOT, THE HOOF BEING RE- posterior and inferior angle of the cartilaginous MOVED. plates. This portion of the cushion is, like the 1, Heel; 2, Coronary cushion; anterior face, covered by a cellulo-fibrous expan- gr aera pawns sion, which separates it from the skin of the pas- 5, Lamine of the bars; ¢ *¢™; this expansion is attached, by its lateral Velvety tissue of the sole, margins, to the posterior border of the and continued, superiorly, on the surface of the anterior expansion, with which it soon unites. The summit (point or apex) forms a sharp border, more or less regularly convex; it is fixed into the plantar face of the pedal bone, in front of the semilunar ridge and the insertion of the perforans tendon, with which the plantar cushion mixes its fibres at this part. The lateral borders are wider behind than before, in consequence of the wedge-like shape of the whole organ; they are continuous with the inner face of the lateral cartilages, as already indicated in describing the latter, The organisation of the plantar cushion differs much from that of the cartilages. It has for its base a fibrous structure, continuous with that which constitutes the fundamental framework of these ; this structure is very close towards the infero-posterior part of the organ, and becomes gradually looser as it leaves this region; the meshes it contains are filled with a yellow pulp composed of fine, elastic, and connective fibres, in the midst of which some adipose cells are found, (I have attentively examined this yellow pulp, and ! \ N — 4 | THE INTEGUMENTARY APPENDAGES. 803 — that it is essentially constituted by adipose tissue.) Numerous ; vessels and nerves complete this structure. “B. Tue Keratrocenovs Memprane, or Suscornevs Inrecument.—The keratogenous membrane envelops the extremity of the digit, by spreading over the terminal expansion of the tendon of the extensor pedis, through the medium of a fibrous fascia—a dependency of the lateral cartilages; and also over the inferior moiety of the external face of these cartilages, the bulbs of the tar cushion, pyramidal body, anterior part of the plantar face of the ird phalanx, and over the anterior surface of the same bone. It covers all these parts like a sock, and the hoof incloses it, as a shoe does the human foot. This membrane becomes continuous with the skin of the digital region at a circular line that intersects the middle portion of the second phalanx, and inclines obliquely downward from behind to before. Below this line, in front and laterally, the subungular tissues form a semicylindrical pro- tuberance, covered with villi, and designated the “bourrelet.” (This elastic prominence has received several most inappropriate names from English farriers and hippotomists, such as “coronary ligament,” “ coronary substance,” “ cutiduris,” etc. From its function, structure, situation, and its analogy to the plantar cushion. I have designated it the “ coronary cushion.’ ) On the plantar cushion and the lower face of the pedal bone, this mem- brane is also a villous tunic—the velvety tissue, which is continuous, towards the bulbs, with the extremities of the coronary cushion. The portion spread over the anterior face of the third phalanx constitutes the laminal or “leafy tissue,” so called because of the ine or parallel leaves seen on its sur- The three regions of the keratogenous apparatus will be successively studied. 1. Coronary Cusnion.—This part is the matrix of the wall of the hoof, and is lodged in a cavity excavated at the upper border of this part of the horny case. It forms, ac- cording to the expression employed by M. Bouley, a rounded prominence, which projects like a cornice above the podo- phyllous tissue. Its inferior border is separated by a white zone from the upper extremity of the laminw, which constitute this boundary. The superior border is limited by a oer projecting margin named the peri- ¢ ring, because it originates the horn of periople. Between this margin and the | repar, view oF THE HoRSE’s FOOT, cushion is a sharply defined groove, __ APTER REMOVAL OF THE HOOP. The extremities, narrower than the middle 4, perieplic ring, divided by a narrow portion, on arriving at the bulbs of the — groove from the coronary cushion, —— cushion, bend downwards into the 2; whieh as penpers with ae ‘ antar cushion, 4, and joins e they - ospggherinadld heya ~ —_—_ drs Fiseeiar lamine, 3, through the beco medium of the white zone. tissue. The surface of the organ shows filiform prolomaatone, a little constricted at their base, and named papilla, villo-papille, villi, and lone ore whose F 804 THE APPARATUS OF THE SENSES. size is greatest towards the lower part of the cushion ; those of the perioplic _ ring are smallest. Contained within the minute apertures at the u of the wall, these papille, considered as a whole, and when the hoof has been removed by maceration, form a tufty surface most perfectly seen when the foot is immersed in water. The structure of the coronary cushion resembles that of the derma, of which it is in reality only a continuation. It comprises a fibrous frame- work, remarkable for its thickness and its condensation, with a considerable’ number of vessels and nerves, whose ramifications may be followed to the extremity of the villi. It owes to its great vascularity the bright red colour it shows on its surface ; this colour is sometimes masked by the black pigment belonging to the mucous portion of the hoof. r have found a notable quantity of adipose tissue in the cushion.) — . Vetvety Tissur.—Much thinner than the plantar cushion, the vel- vety tissue, the formative organ of the sole and frog, extends over the whole of the plantar region of the third phalanx, as well as the plantar cushion, whose bulbs and pyramidal prominence it covers by adapting itself exactly to the irregularities of this elastic mass. : Its surface, which altogether resembles the general configuration of the plantar surface of the hoof, is divisible into two regions: a central, corre- sponding to the pyramidal body and the frog, and continuous on the bulbs of the cushion with the extremities of the coronary cushion and the perioplie ring, but chiefly with the latter; the other, peripheral, is pane the horny sole, separated from the podophyllous tissue by the plantar border of the foot, somewhat encroached upon posteriorly by the lamine corresponding to the bars, and is continuous, above these lamin, with the plantar cushion. The surface of the velvety tissue is studded with villi similar to those of the coronary cushion, and about the same in size. The longest are towards the circumference of this surface, and the shortest in the median Jacuna of the pyramidal body ; all are lodged in the porosities on the inner surface of the horny sole and frog. This tissue shows the same organisation as the coronary cushion. The vascular corium, forming its base, is thickened at its peripheral portion by a fibrous network named the plantar reticulum, in the meshes of which are sustained the veins of the inferior face of the foot. 1" 8. Lamina Tissur.—This part of the keratogenous membrane is also very frequently designated the podophyllous tissue (and still more frequently, in this country, as merely the lamin). It is spread over the anterior face of the third phalanx, occupying the interval between the plantar border of that bone and the lower margin of the coronary cushion; its width is, therefore, greater at the anterior part of the phalanx than on its sides, where the extremities of the membrane are reflected below the bulbs of the plantar cushion on to the velvety tissue. This membrane owes its name to the leaves it exhibits on its superficies ; these are from five to six hundred in number, run parallel to each other, and are separated by deep channels, into which are dovetailed analogous leaves on the inner side of the wall of the hoof; they extend from the white zone that limits the inferior border of the coronary cushion—where they are — not so salient—to the plantar border of the foot, where they each terminate in five or six very large villous prolongations, which are lodged in the horny tubes at the circumference of the sole. The leaves (lamine) of the podophyllous tissue increase in width from above to below; their free margin is finely denticulated, and, under the _—e ‘ —_ — a THE INTEGUMENTARY ARPENDAGES. 805 influence of any inflammatory cause (laminitis, ablation of the wall), these denticule become largely developed, and transformed into veritable papille. Their sides are traversed by folds, about sixty in number, which pass uninteruptedly from top to bottom. These secondary leaves, or lamelle, are fixed obliquely on the sides of the laminw, as the barbules of a feather are attached to the barbs. The podophyllous tissue is not in immediate contact with that of the keraphyllous tissue, or horny lamine ; between the two there is a mass of soft, elliptical cells, always destitute of pigment, easily stained with carmine, and appearing to stud the ramifications of the vascular laminew. A trans- verse section of the union of the hoof with these laminw, when treated with carmine, presents a very fine aspect, appearing as so many fern or acacia-of- _ Judea leaves placed between the keraphyllous lamine: the principal nerve, and the secondary nervules of the leaves, being represented by the lamina and its lateral ridges, the limb of the leaves by the young cells spread around the latter. The structure of the podophyllous membrane resembles that of the other parts of the keratogenous apparatus. Its corium is, like that of the peri- pheral portion of the velvety tissue, separated from the os pedis by a fibrous reticulum, which supports the veins, and forms, to some extent, the periosteum of the third phalanx. _ The leaves of the podophyllous membrane are immense lamellar papille, which should be included among the principal instruments concerned in the tactile sensibility of the Horse’s foot, and which play a really mechanical in concurring, by their dovetailing with the keraphyllous (or horny) Tesaion, to assure the solidity of the union of the hoof with the living parts. The cells which multiply on their surface have usually but little share in the formation of the horn. This will, however, be alluded to hereafter. b. Description of the Hoof. The hoof of the Horse, considered as a whole, represents a kind of box that envelops the inferior extremity of the digit, by fitting closely on the ous membrane, to which it is united in the most intimate manner by a reciprocal penetration of the prolongations into the cavities that exist on the surfaces in contact. Its general shape is, as was demonstrated by Bracy Clark, that of the moiety of a cylinder cut obliquely across its middle, and resting on the surface of this section. In nearly all feet, however, it is slightly conical. Prolonged maceration separates it into three portions: the wall, sole, and frog. SWiet.—The wall, also named the crust, is that part of the hoof which is t when the foot rests on the ground. This thick plate of horn covers the anterior face of the foot, and, gradually narrowing in width and diminishing in thickness, passes round each side until it reaches the bulbs of the plantar cushion, when its extremities are sharply inflected inwards, between the frog and internal border of the sole, becoming confounded with the latter about its middle or anterior third, after being greatly reduced in breadth and substance. _ The middle, or anterior part, of this horny envelope is popularly known as the toe, the two sides of which are designated as outside and inside toe ; the lateral regions constitute the quarters ; the heels are formed by the angles 806 of inflexion of its extremities; while these extremities themselves, passing along the inner border of the sole, are termed the bars. Fig. 374. HOOF JUST REMOVED FROM THE FOOT; SIDE VIEW. a, Inner surface of periople, or coronary frog-band, with some hairs passing through; a’, Outer surface of same at posterior part of foot; a”, A sec~ tion through the wall to show its thickness; 6 to c, Quarter of the hoof, from }b to the front is the out- side (or inside) toe; from c to d the outside (or inside heel); e, Frog; f, Bevel on upper margin of wall for reception .of coronary cushion; g, Keraphylla, or horny laminz. THE APPARATUS OF THE SENSES. Examined with regard to the direction that it affects in its relations with the ground, this envelope is seen to be much inclined in its middle region or toe, and this obliquity gradually diminishes until the posterior part of the quarters is reached ;_ at this point the wall is nearly perpen- dicular. The following are the characters it offers in the conformation of its faces, bor- ders, and extremities : The external face, convex from side to side, and perfectly straight from the upper to the lower border, is smooth, polished, and shining: an appearance it owes to a thin horny layer, independent of the wall proper, designated the periople. } This periople forms, on the upper part of the wall, a kind of ring, continuous with the bulbs of the plantar cushion, and with the frog, of which it is only a dependency ; responding, by its upper margin, to the perioplic ring, which secretes it; towards the lower part of the wall it is gradually lost, friction incessantly thinning and destroying it. Fig. 375. h HOOF, WITH OUTER PORTION OF THE WALL REMOVED TO SHOW ITS INTERIOR, The inner face presents, over its entire extent, the white parallel leaves which dovetail with the laminew of the podo- phyllous tissue. Collectively, these are named the keraphyllous tissue. The superior border is bevelled-off, on its inner aspect, into a circular con- cavity, into which the plantar cushion is received. This excavation is named the cutigeral cavity, because of its relations ; it offers on its surface a multitude of minute openings—the commencement of the horny canaliculi which receive the villosities of the cutiduris. The inferior border, in contact with the ground, and subjected to wearein unshod animals, is united inwardly, and in the most intimate manner, with the circumference of the sole. The extremities, constituted by the reflected and re-entering prolongations known as the bars, form, outwardly, the external side of the lateral lacunz of the frog: they are provided, inwardly, with lamine like the rest of the wall: The upper margin of these prolonga- ; a, a, Periople, or coronary frog-band ; ), Cavity in upper part of wall for coro- nary cushion ; c, Upper, or inner, surface of “ bar ;” d, Vertical section of wall; a’, The same at the heel; e, Horizontal section of ditto; f’, Horny lamine of bar; f”, Ditto of wall ; f’", Lateral aspect of a lamina; gy, Upper, or inner surface of the horny sole; A, Junction of the horny lamin with the sole (the “ white line”); i, Toe-stay at the middle of the toe; #, Upper, or inner surface of the horny frog; /, Frog-stay; m, Cavity corresponding to a branch of the frog; n, Ditto corresponding to the body of the frog. THE INTEGUMENTARY APPENDAGES. 807 tions is confounded with the frog and sole; the lower appears between these two ~ etn and is effaced at a certain distance from the point of the frog. .—The sole is a thick horny plate comprised between the inner bor- der of the wall and its reflected prolongations ; thus occupying the inferior face of the hoof. It offers two faces and two borders or circumferences. The inferior, or external face, forms 1 more or less concave surface, according to circumstances. The superior, or internal face, corresponds to the peripheral portion of the velvety tissue; it shows a multitude of little apertures analogous to those of the cutigeral cavity, into which are inserted the papille of the keratogenous membrane. e external border, or large circumference, is united, throughout its extent, to the inner contour of the lower border of the wall, by means of its denticule, which are reciprocally dovetailed into those on the inner face of the wall near its inferior border. The internal border, or small circumference, is a deep, V-shaped notch, widest behind, which cor- responds to the bars, and at the bottom of which the point of the frog is fixed. Froe.—This is a mass of horn, pyramidal in shape, and lodged between the two re-entering portions of the wall. It offers four planes (or sides), a base, and a summit (or point). The inferior and the two lateral planes con- stitute the external surface of the organ. The first is hollowed by a longitudinal excavation, which is shallow in well-formed hoofs, and is named the median lacuna of the frog, separating PLANTAR OR GROUND SURFACE Fig. 376. the two salient portions, or branches, which di- verge posteriorly and join the heels. The other two planes are directed obliquely downwards and inwards; they adhere closely, at their upper third, to the external side of the bars, and anteriorly to the inner border of the sole. “This union is so close that no line of demarcation is appa- rent between these parts, and their separation can only be obtained by prolonged maceration. The non-adherent, or free portion, forms the inner side of the angular cavities known as the lateral lacune, or commissures of the frog, whose external OF A HOOF; RIGHT FOOT, The interval from a to a@ repre- sents the toe; Froma to 4, b, outside and inside quarters; c, 0, Commencement of bars; d, d, Inflexions of wall at the heels, or “ buttresses ;” e, La- teral lacuna; f, f, f, Sole; g, White line; g’, g’, Ditto be- tween the sole and bar; A, Body of frog; #, Branch of frog; 4, k, Glomes, or heels of frog; ¢, Median lacuna. side is constituted by the inferior face of the bars.” --Bouley. The superior plane, forming the internal face of the frog, is cribbled with holes like that of the sole, and is exactly moulded on the pyramidal body of the plantar cushion. It also offers a triangular excavation, divided posteriorly into two latter channels by a prominence directed from before backwards, to which Bracy Clark gave the name of frog-stay, but which M. Bouley prefers to designate the stay (aréte) of the frog. The base or posterior extremity of the frog, constituted by the extremities of its branches, forms two rounded, flexible, and elastic eminences separated from each other by the median lacuna; they cover the angles cf inflexion of the wall, and are continuous at this point with the perioplic band. Bracy Clark named them the glomes of the frog. With regard to the summit, or anterior extremity of the organ, it is a 808 THE APPARATUS OF THE SENSES. point wedged in the re-entering angle comprised between the two portions — of the inner border of the sole. ; om In the Ass and Mule, the hoof is always narrower, laterally, than that of the horse; the wall is always higher and thicker, the sole more concave, the frog smaller and deeper seated at the bottom of the excavation formed by the sole, and the horn is much more hard and resisting. (The angle of the wall of the hoof in front varies from 50° to 56°, though usually erroneously stated to be 45°. The inner face of the wall, — at the middle of the toe, and in a line with the frog-stay, frequently shows a more or less salient and ccnical prominence—base towards the lower i of the wall—which corresponds to a vertical depression in the os pedis. Vallada imagined that this projection served to unite the wall and sole more closely, but it is far more probable that its function is the same as that of the frog-stay—to maintain the position of the os pedis, and prevent its rotation within the hoof. I have, therefore, named it the “ toe-stay.”) Srrvoture or THE Hoor-Horn.—The structure of the horn has been the object of a great number of researches; Gurlt, Delafond, Bouley, Gourdon, and Ercolani' have given descriptions of it, and we have also some details to add to the labours of these authorities. 2 The horny substance constituting the hoof of Solipeds, has a fibrous appearance; this is most conspicuous in the wall, less apparent in the frog and deeper portions of the sole, but impossible to distinguish in the superficial layer of the latter, where the disintegration continually taki place separates the horn in scaly fragments of varying thicknesses an extent. The consistence of the horn is always less in the frog than in the sole and wall. Its tint is in some hoofs black, in others white, and in others again a mixture of these two. The inner face of the wall, however, is never black; and when the lower part of the limb is partially or wholly white, we may be.sure that all the thickness of the wall will either be white at corresponding points in the former, or entirely so in the latter. Except in the keraphyllous tissue, the minute structure of the hoof-horn always exhibits the same characters; everywhere it is perforated by eylin- drical canals whose upper end is funnel-shaped, and these contain the papille of the matrix, whether they belong to the coronary cushion or velvety tissue ; while the lower end reaches the inferior border of the wall; or lower face of the sole and frog, according to their situation. It is rare to find them in the horny laming. All are rectilinear, with the exception of those of the frog, which are somewhat flexuous; and all have the same oblique direction downward and forward, following the inclination of the anterior portion of the wall. They are, therefore, almost exactly parallel to each other, not only in the same, but in the two different regions. Their diameter varies considerably, though the smallest are always those of the periople; in the wall, they are smaller as they approach the outer surface. These tubes are not mere canals hollowed out of the horny substance ; on the contrary, they have very thick walls which are formed of numerous concentric layers, one within the other, and the horny tissue connecti them has not the same apparent stratiform disposition. Filled by the papille of the keratogenous membrane at their superior extremity, these ' (The researches of Professor Rawitsch must not be omitted. They will be found in Volume xxviii. of the ‘Magazin fiir Thierheilkunde,’ and also in a little brochure entitled ‘ Ueber den feineren Bau und das Wachsthum des Hufhorns. Berlin, 1863, Leisering must likewise be referred to. My own researches are published in the ‘ Veterinarian’ for 1871.) THE INTEGUMENTARY APPENDAGES. $09 canals are not empty for the remainder of their extent; but contain a : — white substance, which is so opaque that it appears of a fine hue when examined as a transparency in the microscope. This matter is not deposited in.a uniform manner in the canals, but irregularly-looking, like a knotted cord or a necklet of beads; and, where it does exist, it does not always exactly fill the calibre of the tube, an interval being observed between the inner face of the latter and the intratubular deposit. Sometimes it is seen without the canals, among their concentric lamella, and even in the horny intertubular substance. _ If we are desirous of completing our knowledge of the minute organ- isation of the hoof-horn by studying the anatomical elements constituting it, we will find that it is formed of epithelial cells belonging to the kind most wide-spread in the economy—pavement epithelium. These horn ithelial cells are very thin, pale, polygonal, and generally oblong, have ly defined borders and finely granular faces, sometimes showing a nucleus containing a single or multiple nucleolus. The nuclei sometimes occupy the centre, at other times another part of the cells—even their margins; and they also con- tain pigment granules more or less coloured and numerous. Acetic acid acts very slowly on them, and is limited to making them more transparent. Potass and soda at first softens, then distends them, causing their granulated aspect to disappear, and rounding their contours; afterwards, they be- come quite diaphanous, and finish by being com- pletely dissolved. , Examined in their reciprocal relations, these ial cells are not seen to be agglomerated confusedly together, but are, on the contrary, dis- posed in a regular manner, forming a real frame- work that wonderfully concurs in assuring solidity and flexibility. In the walls of the tubes we see them arranged horizontally around the canal, and ORN-CELIS FROM THE SOLE stratified from within to without, so as to form On; 298 BOM. successive concentric layers. In the intertubular “ Toons peg ee bs horn they are disposed differently, their stratifi- vies “the lowed idea, pe cation being no longer parallel to the direction of dead horn of the sole. the tubes, but perpendicular to it, and piled upon each other in the intervals separating the latter. This change of direction . does not occtr suddenly; at the limits of the tubes epithelial cells are seen lying obliquely. In a transverse section of the wall, there are observed around the tubes, in the intertubular substance, as well as in the horny lamina, small irregularly elliptical spaces containing a solid denticulated mass of a brownish tint, which is easily stained with carmine. These bodies are more elongated in the intertubular substance than in the walls of the tubes, and have a certain resemblance to the cartilaginous capsules, but especially to the bone cavities filled by their contents. Independently of the hard, dry, and flattened cells, there is found an opaque substance that partly fills the tubes, and which is also sometimes met with in their walls. This material does not differ from the last in its nature ; it is also formed, as has been asserted by Gourdon and Ercolani, of irregular granular cells which are stained by the carminate of ammonia. Fig. 377. $10 THE APPARATUS OF THE SENSES. Pigmentary-corpuscles exist in the substance of the coloured horn, — and are disposed singly, or in small masses, in the epithelial cells of the intertubular substance. The presence of these corpuscles has been denied, and the coloration has been attributed to a greater condensation, at certain points, of the epithelial elements. Fine pigment-granules are di i in the cells, but it is evident that beyond these there are at different points pigment-corpuscles ; for, after treating a section of coloured horn with soda, the epithelial elements are distended, become pale, and disappear, leaving, however, here and there, masses of black granulations. These pigmentary-corpuscles -are absent in white horn. Drvetorment or THE Hoor.—The hoof being a dependency of the epidermis, is developed like it: that is, by the incessant formation of cells in the layer that corresponds to the rete mucosum, at the expense of the plasma thrown out by the numerous vessels in the keratogenous membrane. The velvety — tissue forms the sole and frog; the perioplic ring the periople, and the coronary cushion the wall. In these different parts, the epithelial cells multiply, CONSTITUENT ELEMENTS 8nd become flattened in layers parallel to the surface OF THE WALL. that secretes them, and in proportion as they recede a, Horn-cells; 6, Horn- from that surface; so that the wall grows from its fibre from the hoof of superior to its inferior border, and the other two parts ra - tts nor g nie of the hoof from their internal to their external face. i of the cells. a The villosities of the coronary cushion and the velvety tissue ure the organs around which the epi- thelial lamelle are grouped, and their presence determines the tubular structure of the horn; their function is completed by the exhalation of a particular fluid that maintains the flexibility of the hoof, and, probably, by the development on their surface of the irregular cells which cluster in the interior of the tubes. be The leafy tissue, in a normal condition, does not concur to any extent in the development of the wall. The cells covering it are multiplied in describing a downward and forward movement; and though they are certainly applied to the inner face of the wall, yet they do not constitute the horny laming. The latter are formed on the coronary cushion, at the commencement of the vascular laminw, and they descend with the wall in gliding along the surface of the layer of cells separating them from the latter ; this downward movement is facilitated by the multiplication, in the same sense, of these cells. This opinion as to the function of the vascular lamine is based on comparative anatomy, on the presence of some lon- gitudinal tubes in the horny lamine, and on pathological observations. When the podophyllous tissue is inflamed, whether or not it is exposed, its latent activity is quickly manifested, and it rapidly throws out a large quantity of hard consistent horn, traversed by tubes which, according to M. Gourdon, are directed obliquely backwards. These tubes are more irregular than those of the normal wall, are disposed in parallel series, and are formed around the villo-papille developed on the free border of the lamine. In this horn, produced by the vascular laminw only, there are never observed between these latter the horny plates of cells—sharp and Fig. 378. THE INTEGUMENTARY APPENDAGES. 811 distinct in the midst of the other cells, as in those of the wall formed by the coronary cushion. The horn thrown out on the surface of the podophylle, immediately after the removal of a fragment of the wall, is not a definitive horn, but must be replaced by that from the coronet. This substitution is complete ; as a microscopal examination proves that the wall which descends from the * Fig. 379 HORIZONTAL SECTION OF THE JUNCTION OF THE WALL WITIL THE SOLE OF THE HOOP. a, Wall, with its horn-tubes; 6, b, Horny lamine projecting from the wall; ¢, ¢, Horn-tubes formed by the terminal villi of the vascular laminz, the horn surrounding them and occupying the spaces between the horny lamin, con- stituting the “ white line ;” d, Horny sole, with its tubes. cushion, and is furnished with horny lamin, passes beneath the provisional wall, and glides downward—by the combined action already mentioned—over the surface of the soft cells of the vascular laminw. As soon as the latter are covered by the proper wall, their marginal papilla become atrophied, and they again assume the limited function pertaining to their physiological condition. ; Fig. 380. ee at ieee 2 id C ‘ c” a” ad’ e HORIZONTAL SECTION OF THE WALL, AND HORNY, AND VASCULAR LAMIN2:, TO SHOW THE JUNCTION OF THE LATTER AND THE LAMINELLA. a, Inner portion of the wall with the lamin arising from it; 6, Vascular lamine ; c, Horny lamina of average length; c’, ¢c’, Unusually short lamina; c¢”, c”, Laminella on the sides of the horny laminw; d@, Vascular lamina passing between two horny ditto; d’, Vascular lamina passing between three horny lamine; @”, Lateral laminelle ; ¢, ¢, Arteries of vascular laminw which have been injected. (The description of the disposition of the epithelial cells given by Chauveau does not coincide with my own observations. As he correctly 812 THE APPARATUS OF THE SENSES. states, these cells are formed in planes parallel with the strface that secretes them; consequently, around the papille they are more or less vertical, while between them they are horizontal. The walls of the tubes, or fibres, are therefore composed of cells disposed in a vertical manner; while in the interfibrous horny matter they are arranged in the opposite direction. The loose nodulated contents of the tubes is composed of cells thrown off from the termination of the papilla, and corresponds to the pith —__ of feathers. The soft cells interposed bétween the vascular and horny laminew are carried down to the lower margin of the wall, where, with the elastic horn secreted by the papilla which terminate the former, they constitute the peculiar light-coloured band, or “ white line,” which marks the junction of the sole with the wall (Fig. 379). This intermediate band of soft flexible horn at this point obviates tearing of the sole from the wall, and fracture of the former, The cells of the horny laminew are more or less fusiform. ' M. Chauveau has also evidently overlooked the presence of beautiful lateral leaflets on the sides of the horny lamin, corresponding to those on the vascular leaves. These were observed by me in 1858; in 1862 they were described by Rawitsch and Ercolani, and, at a later period, by Colin of Alfort and Leisering of Dresden. They are very conspicuous in a well- prepared section (Fig. 380, d’’). It should be observed that the growth of the wall of the hoof is indefinite, but that the sole and frog, after attaining a certain thickness, exfoliate. For complete details as to the physiology of the Horse’s foot, the student is referred to the ‘ Veterinarian’ for 1871.) 2. The Claws of Ruminants and Pachyderms. In the Ox, Sheep, and Pig, the plantar cushion covers the bulb of thé heel of each digit, where it forms a convex mass; it extends to the insertion of the deep flexor tendons of the phalanges, in becoming triangular in shape, and thinner. The horny envelope covering the extremity of the digits of these animals is a kind of cupola, having almost the form of the third phalanx; it is usually named the claw. The claw of the Oz has an outer face oe the wall of the Horse’s hoof, and an inner face which is slightly concave, and marked by undulating grooves; owing to t}.is concavity, the two claws of each foot only touch at the extremities of their adjacent — faces. The plantar region of the claw is slightly depressed, and but little develaguall it is chiefly made up of the plantar cushion, which is covered by a thin layer of supple tubular horn. On the interior of the claw is seen a wide shallow cutigeral cavity, perforated by very fine openings, and lamine thinner and more numerous than in the Horse’s hoof. The tubes of the claw-horn are very small, being surpassed in diameter by those of the Lege wel) sole. Above and behind each claw are two little rudimentary horny capsules, which are named ergots. (Each contains a small bone, which is not attached to the skeleton in Ruminants. In the Pig, these rudimentary claws are larger, and are connected with the bones of the leg. In this animal the horn of the claws is altogether thinner, softer, and less resisting than in Solipeds. The ergot is the representative of those digits which are apparently absent in the solid and cloven foot.) 3. The Claws of Carnivora. In these animals, the third phalanx of the i is enveloped in a conical horny sheath that curves downwards like the bone itself. This covering is designated the claw or nail, and offers somewhat the same organisation as the horns of Ruminants; it is developed, and grows in the same manner, as the hoof of Solipeds, its matrix being a prolongation of the corium which extends over the third phalanx, after dipping into the circular furrow at the base of that bone. Placed at the extremity of the digital region, the claw in these animals is not utilised in locomotion, as the foot does not rest on the ground by the extremities of the depression in the interdigital spaces, by means of a smal ‘4 gr THE APPARATUS OF TASTE. 813 but by the whole plantar surface. Therefore it is, that we find on this face a kind i i covering five fibro-adi tubercles: four small ones placed along the principal digits—the fifth or thumb not being sufficiently developed to reach the ground—and a large central one, circumscribed in front by the others. This ar- ent is «lestined to diffuse the pressure caused by the weight of the body (and, Sotbiles, to ameliorate the concussion arising from the exertions these animals make, as well as to insure their footsteps being noiseless in approaching their prey). In the Dog, the claws may be used for burrowing in the ground. In the Cat, the claws are very sharp and retractile; bein — of erection and ellow elastic ligament from the second to the third phalanx. This animal’s claws constitute its most pow weapon of attack and defence. S 4. The Frontal Horns. These are conical horny sheaths, more or less large, crooked, and annulated transversely, formed by concentric layers of epithelial cells and some pigment corpuscles. ‘The horns grow like the epidermis and the hair, their elements being secreted by that portion of the corium spread over the osseous cores of the frontal bones, and which completely envelope these; this portion of the skin is remarkable for its great vascularity. (The length, direction, and | pny form of the horns varies in Ruminants, not only with regard to species, age, and race, but also thesex. The Bull, in the Bovine rhage nerally has short, thick, powerful horns; the Cow long and slender ones; and the Oz aie. long, and strong ones. Some breeds have no horns at all; the same with the Goat species, though generally the horns in these are long, flattened, and curved backwards and downwards. With the Ram, the horns are sometimes immense and very a being of a spiral form. They are usually less, or altogether deficient, in the . In the Bovine species, the transverse rings on the horns serve to indicate the age, the first appearing after two years.) 5. The Chesnuts. This name is given to a little horny (oval or round) plate found, in the Horse, on the inner face of the fore-arm—in the lower third of the region, and at the upper extremity of the inner face of the metatarsal bone. It is com of a mass of epithelial cells, arranged in tubes like the horn of the hoof. In Solipeds, the chesnut is the representative of the thumb. That on the posterior limbs is absent in the Ass; in the Mule it is very small (In fine-bred Horses, this horny production is much less developed than in the coarser breeds. It is always smaller in the hind limbs. In the hind and fore-legs, we also find a similar, but smaller corneous mass, growing from the skin of the fetlock, and named the ergot. Like the chesnut, it bears the same relative development in fine and coarse-bred horses. ) CHAPTER II, APPARATUS OF TASTE, Tue sense of taste permits the appreciation of savours, or the sapid properties of bodies. Two nerves—the chorda tympani and the lingual branch of the ninth pair —appear at present to be the only sensory filaments endowed with the exercise of this function. They ramify in the lingual mucous membrane, which is thus made the organ of taste. 84 THE APPARATUS OF THE SENSES. The tongue and its investing membrane having been described at page 835, their anatomy need not again be referred to; but we must glance at — the organisation of the latter in considering it as the special apparatus of gustation. This will necessitate a few words on the free surface of the mem- — brane which comes into contact with the sapid bodies, and some consider- ations on the terminations of the nerves which transmit the imp produced by these bodies to the brain. ir Free Surrace or tHe Lineva, Mucovs Memprane.—This surface is studded by a multitude of papillary prolongations, which are nearly all limited to the upper surface of the tongue, to which they give a tufty © iS appearance. Their form and volume, as mentioned at page 336, are very variable, according to their situation: some are microscopic, while others form voluminous caruncles; others, again, are long, conical, and filiform ; another variety is round or depressed, representing a hemispherical tuberele scarcely projected beyond the general surface, or placed at the bottom of an excavation in the mucous membrane. The latter constitute the calyciform papille (p. circumvallate, p. lenticulares), and are considered the true or, of gustation ; the others are the fungiform (p. capitate) and filiform apt, which play a mechanical part on the surface of the tongue. The calyciform papille in the Horse are two in number, and situated near the base of the tongue; their diameter is so considerable that they have been named the blind or cecal openings (trous borgnes). They are the principal, but not the only organs of taste. Their surface is mammillated, each prominence corresponding to a single papilla, and being placed below the level of the raised border encircling them. A deep fossa surrounds them, and limits at their base a pedicle, which unites them to the other portions of the mucous membrane. The calyciform papille show, around their peduncle, a band of adenoid tissue ; and in their substance conglomerate glands, as in other parts of the mucous membrane. They are covered by an epithelium containing some scattered pigment granules, the thickness of which is much diminished at the bottom of the fossa circumscribing them. TrERMINATION oF THE Gustatory Nerves.—The hypoglossal is the motor nerve of the tongue, the lingual the nerve of general sensibility, and the chorda tympani and glosso-pharyngeal the filaments of special sensibility : this appears to be clearly ascertained from the recent experiments and observations of Lussana. The lingual branch of the glosso-p nerve gives gustatory sensibility to the posterior third of the tongue; the chorda tympani to the anterior two-thirds. The gustatory nerves present, as do all those of the organs of sense, a particular mode of termination. First indicated by Axel Key, their special manner of terminating has been carefully studied by Lowen and Schwalbe. According to these anatomists, the terminal nerve-tubes lose their medul- lary envelope and, reduced to their axis-cylinder, are thrown out in small oval masses which might be termed gustative bulbs. These bulbs are more particularly placed around the pedicles of the calyciform papille, in the substance of the epithelium. They are fusiform, their inner extremity rests on the mucous derma, where they receive the terminal nerve-tubes; and their external extremity reaches the epithelial layer, where they are seen either between two cells, or in an orifice pierced in a single pavement cell. Each bulb is composed of a small cluster of cells, which are distinguished from each other by their character and position; those occupying the axis of the organule are the gustative cells ; they are in communication with the i ale THE APPARATUS OF SMELL, 815 nerye-tubes on one side, and on the other are furnished, for the most part, with rods which attain the free surface of the tongue. The superficial, or protective cells, completely envelop the preceding; they are a kind of epithelial-cells imbricated like the skins of an onion. _ These sensitive organs are very numerous in the walls of the calyciform papille. Schwalbe reckoned their number at 35,000 in the papille of the Ox. They are not met with in these papille only; Lowen has found them in a large quantity of fungiform papille, if not in all. There is nothing extraordinary in this, as the whole surface of the tongue may, in various degrees, appreciate savours. (Szabadféldy has described small oval or pyriform bodies, lying with their long diameter parallel to the surface. The axis-cylinders of the gustatory nerves enter these, and terminate at their lower “i in a slight swelling; so that they resemble small Paccinian DIFFEKENTIAL CHARACTERS IN THE APPARATUS OF TASTE IN OTHiR THAN SOLIPED ANIMALS, In the domestic mammifers, the differences in this apparatus are found in the number an | variety of forms of the papille of the tongue. In Ruminants, the calyciform papille are disposed in two rows at the base of the tongue; they are smaller than in the Horse, but more numerous—about a dozen being counted in each row. In the Oz, the filiform papille are covered by a horny sheath, which renders them hard to the touch. The Pig, like Solipeds, has only two calyciform papille. In the Dog and Cat, there are two principal papille, and in their vicinity some smaller ealyces. The filiform papille are composite, and covered by a thick horny layer. Between them, regularly placed, are seen tlie fungiform papille, which have a brilliant uspect when looked at obliquely to the surface of the tongue. COMPARISON OF THE AI'PARATUS OF TASTE IN MAN WITH THAT OF ANIMALS. This has been already alluded to at page 364. CHAPTER III. APPARATUS OF SMELL. Tue sense of smell gives the appreciation of odorous emanations to animals. The active instruments of this sense are the filaments of the first pair of encephalic nerves, which ramify in the upper part of the pituitary membrane ; this becomes, with the cavities it lines, the olfactory apparatus, These parts have been already referred to at page 444. (‘The olfactory filaments, passing down from the olfactory ganglion, form a plexus upon the surface of the pituitary membrane. These filaments, as already noted, differ widely from those of the ordinary cephalic nerves, in containing no white substance of Schwann, but are nucleated and finely- ular in structure, and resemble greatly the gelatinous form of nerve- Their distribution is limited to the membrane at the upper third of the nasal septum, the upper part of the turbinated bones, and the wall of the nasal cavities adjoning the cribriform plate of the ethmoid bone: all this surface being covered with an epithelium of a rich sepia-brown hne. As has also been mentioned, Schultze divides these cells into two sets: 816 one (Fig. 382, a) being described as terminating externally by truncated Fig. 381, FIBRES OF ULTIMATE RAMIFICATIONS OF OLFACTORY NERVES OF DOG. ae THE APPARATUS OF THE SENSES. —— a4 flat surfaces, which cannot be observed to be y a any membrane separate from the contents of the « These contents appear to consist of protoplasma wi yellow granular aspect externally, while at the lone “2 part an oval nucleus imbedded in transparent proto pes can be easily seen. At their attached end, these come attenuated, and may be traced inwards for a me siderable distance until they expand into a broad flat — | sheet or plate, which is never coloured, though it fre- quently presents a granular appearance. The processes — ; passing off from this appear to be continuous with the __ fibres of the submucous connective tissue, Towards — the margin of the true olfactory region, cells analogous to these are met with, the only difference being that they present a well-defined band or seam at their free extremity, which is surrounded by a circle of cilia (Fig. 382, ¢). The cells of the second set 382, b) are continuations of the nerves, and have named olfactory cells. They are thin, fibrous, or rod-like bodies, terminating at the same level as the proper + re epithelial cells, and presenting, when traced inwards, a series of varicose swellings directly continuous with the prolongations of deeper-seated nerve- cells. Clarke states that the nerve-fibres, on reaching the base of the epithelial layer, divide into finer and finer branches, to form a network with Fig. 382, ag; y} CELIS OF THE OLFACcTORY known as the eyelids, whose play over the surface of MUCOUS MEMBRANE, a, b, c, After Schultze; het, r After ‘LAdichart keeps their inner surface constantly moist. Clarke. of the accessory portions of the visual apparatus, we will notice the receptacle . numerous interspersed nuclei, through which they are probably connected with the olfactory cells ( wig. 382, f). The proper epithelial cylinders (d, e e connected at their bases with the septa formed o: the connective tissue belonging to the subepithelial glan- : dular layer.) 7 CHAPTER IV. APPARATUS OF VISION. Desianep for the perception of external images ren- dered visible by the luminous rays, the sense of sight depends upon the excitability of the optic nerve, the terminal extremity of which is expanded as a thin membrane at the back of each eye. The latter is a globular organ lodged in the orbital cavity, attached to muscles which can move it in various directions, and protected by membranous and movable screens the eye is facilitated by the lachrymal fluid, which The essential organ of vision, or globe of the eye, ~ will be first described ; then, under the designation THE RYE. 817 ‘of this globe, or orbital cavity, the muscles that move it, the protective mem- ‘branes or eyelids, the membrana nictitans or accessory eyelid, and, lastly, the oo ney apparatus, which concurs in the protection of the ocular globe by the fluid it incessantly throws out upon its surface, : Arricte I.—Tue Essentrat Orcan or Vision, on Ocunar Grose. (Fig. 383.) {Preparation.—The eye should be as fresh as possible. All the fat and muscles should be carefully removed with scissors, the optic nerve being allowed to remain.) The globe, or ball of the eye, is a spherical shell, whose interior is filled with fluid or semifluid parts, named the humours or media of the eye. The wall of this shell is formed by a continuous, very resisting, colourless envelope, limpid and translucid in its anterior portion, which constitutes the rent cornea, and white and opaque for the remainder of its extent, known as the sclerotica. _ On the inner face of the sclerotica isa second tunie+the choroid : a black membrane that lines the posterior face of the retina, and which, near where the two constituent portions of the external envelope unite, projects into the interior of the eye an elliptical diaphragm with a large opening in its centre —the iris. Immediately behind this disc is suspended or set, like a rose- brilliant, in the centre of a circular zone depending from the choroid, a biconvex body—the crystalline lens, one of the media of -the eye, and which divides the interior of its cavity into two compartments: a posterior, very large, occupied by the vitreous humour ; and an anterior, itself divided by the iris into two chambers of unequal dimensions, which contains the aqueous humour. ‘Viewed externally, and as a whole, the organ resulting from the union of all these parts represents a globular body, the anterior region of which corresponds to the cornea, and is more convex than the other points: a circumstance that tends to increase the antero-posterior diameter of the eye. But as this ocular sphere, to which is added, in front, this segment of a smaller sphere, is sensibly depressed from before to behind, it results that the other two principal diameters— the vertical and transversal — offer about the same dimensions as the first; Girard has even stated that the latter is the least. With an eye hardened by chromic acid, we have found that the transverse diameter measured 0",036, and the vertical 0",040 (1-417 x 1+575 inches). Two paragraphs will be devoted to the description of the constituent parts of the globe: one for the membranes, the other for the media, THE MEMBRANES OF THE EYE. 1. The Sclerotic. (Fig. 383, b.) ' The sclerotic is a white, very solid membrane, forming in itself about four-fifths of the external shell of the eye. Its external face, in relation with the recti muscles and adipose tissue, receives posteriorly, though lower than the middle, the insertion of the optic nerve, which passes through it and the choroid to form the retina, Its internal face is loosely united to the choroid by vessels, nerves, and cellular tissue. In front, the sclerotic shows an elliptical opening whose greatest diameter 34 818s THE APPARATUS OF THE SENSES. is transversal, and whose border, bevelled on the inner side, is closely united to the circumference of the cornea. The substance of this membrane is traversed by. numerous vessels and nerves, and is not of the same thickness throughout; at the back, around the entrance of the optic nerve, it is thickest ; it then diminishes gradually towards the larger axis of the organ, and afterwards increases until it meets the cornea. Fig. 383. THEORETICAL SECTION OF THE HORSE’S EYE. a, Optic nerve; 6, Sclerotic; c, Choroid; d, Retina; e, Cornea; f, Iris; g, 4, Ciliary circle (or ligament) and processes given off by the choroid, though represented as isolated from it, in order to indicate their linfits more clearly; ¢, Insertion of the ciliary processes on the crystalline lens; j, Crystalline lens; %, Crystal- line capsule; /, Vitreous body; m, n, Anterior and posterior chambers; 0, The- oretical indication of the membrane of the aqueous humour; p, p, Tarsi; ¢, q, Fibrous membrane of the eyelids; r, Elevator muscle of the upper eyelid; s, s, Orbicularis muscle of the eyelids; t, t, Skin of the eyelids; u, Conjunctiva; », Epidermic layer of this membrane covering the cornea; 2, Posterior rectus muscle ; y, Superior rectus muscle; z, Inferior rectus muscle; w, Fibrous sheath of the orbit (or orbital membrane), Srrvoture.—The sclerotic is wholly composed of fasciculi of fibro- cellular tissue interwoven in a very close manner, with some elastic fibres and little masses of pigment, especially at its back part. Among these fasciculi a large number pass from before to behind, and these are intersected by others which are placed in a circular manner around the globe. The super- ficial fibres are continuous with the neurilemma of the optic nerve. (The optic nerve, at its entrance into the sclerotic, is very much constricted, and passes through a funnel-shaped, porous mesh of fibrous tissue named the lamina cribrosa, in the centre of which is a larger opening than the others, for the passage of the arteria centralis retinee—the porus opticus. The inner 7 THE EYE. 819 surface of the sclerotic is coated by a thin layer of areolar tissue stained with black pigment—the lamina fusca. ) The arteries of the sclerotic are derived from the anterior and posterior _ ciliary arteries; the veins pass into trunks lying parallel to the ciliary arteries. Nerves have been found in the sclerotic of the Rabbit, but in none other of the domesticated animals. “It is frequently found that in the Ass, particularly when it is old, the back part of the sclerotic is encrusted with - an unmistakable layer of bony matter. This fact was unknown to Carus, who states that in none of the mammalia does this membrane become ossified.”—Lecog. (In Birds, bony plates are found in this region, and some reptiles also have them.) 2. The Cornea. (Fig. 383, e.) (Preparation.—The cornea should be removed with the sclerotic coat, by immersing the eye under water, and making a circular incision with scissors about a quarter of an inch from the margin of the membrane). The cornea is a transparent membrane forming the anterior part of the eye, to whose interior it allows the light to pass. It closes up the anterior ing of the sclerotic, and thus completes the external envelope or shell of the globe, of which it forms about a fifth part. __ Elliptical, like the opening it closes, the cornea presents: 1, Two faces, fectly smooth—one external, convex, the other internal, concave—form the _ external wall of the anterior chamber; 2, A circumference, bevelled on its outer edge, and received into the similar bevel around the sclerotic opening, like the glass of a watch into its case. ; Srrvorure.—Three layers enter into the composition of the cornea: an external, internal, and middle. Middle layer.—This, the proper cornea, is remarkable for its thickness. When p between the fingers, its two faces can be easily made to glide over each other, a proof that its tissue is disposed in superposed and parallel planes; it is indeed possible to decompose the cornea into several laminw and lamell, but as their number varies with the amount of skill employed in their separation, they should be considered as an artificial production of dissection. Microscopically examined, it is found to be formed by bundles of excessively fine conjuntival fibrille, slightly undulating, and arranged parallel to the surface of the cornea. These wavy fasciculi, when placed alongside each other, leave numerous spaces which are oval in a transverse section ; these communicate by means of fine canaliculi, and contain round cellular elements which may move from one space to another. __ Between the fasciculi of the cornea is found a fluid amorphous substance, “a kind of transparent serosity like the cornea itself, which maintains its flexibility, and which, like it, also loses its transparency under the influence of different causes. It is only necessary, in a fresh eye, to squeeze the globe in order to produce a degree of opacity in the cornea which will be more or less great in proportion to the amount of pressure exercised. Is a similar effect produced by the swelling of the eye when the cornea becomes opaque in ophthalmia ?”—Lecogq. The external layer is only the conjunctival epithelium spread over the anterior face of the cornea. This epithelium is stratified, flattened on its surface, but cylindrical below, where it rests on the middle layer, and from which it is not separated, as in many species of animals, by a proper Lanitary membrane. The inner layer is a portion of the membrane of the — oe G 820 THE APPARATUS OF THE SENSES, It is composed of a membrane that becomes slightly fibrous at the periphery of the cornea, where it forms, in passing on to the iris, the pectinated ligament. It has also a covering of polygonal epithelial cells, which are provided with a large nucleus, (Some authorities give five layers to the cornea, the first being the conjunctival. The second consists of a very elastic tissue, pe structureless, and possessing a remarkable tendency to curl up; while boiling, or the action of acids, does not render it opaque as with the other layers; very fine fibres pass obliquely between it and the next layer—the cornea proper—consisting of a large number of strata with branched fusiform cells. The fourth layer is also elastic and like the second, though thinner. The fifth layer consists of the epithelial cells already mentioned. Wilson says that the opacity of the cornea produced by pressure on the globe, results from the infiltration of fluid into the areolar tissue connecting its layers, and that this appearance cannot be produced in a sound living eye, although a small quantity of serous fluid (liquor cornew) is said to occupy the spaces in that tissue.) Vessels.—The cornea has but little vascularity. The vessels form around its borders, and in the Sheep they advance to near the middle of its surface. Nerves.—These were discovered by Schlemm. They penetrate by the periphery of the cornea, and form a network on its surface. According to Kiihne, Hoyer, and Conheim, the ultimate nervous ramifications pass into the epithelium of the anterior face, and arrive between the most superficial cells, 3. The Choroid Coat. (Fig. 383 c.) ( Preparat‘on.—If the cornea has not yet been removed, it and the sclerotic may now be dissected away from the choroid or second tunic. The connections between them are closest at the circumference of the iris, and at the entrance of the optic and ciliary nerves and arteries. Fine blunt-pointed scissors are necessary, A small portion of the sclerotic, near its anterior circumference, is pinched up and clipped off, the edge of the incision is raised, the circumference of the sclerotic divided, and that tunie removed piecemeal; a gentle pressure with the edge of the knife will remove it from its attachments around the circumference of the iris, This dissection is best conducted under water. The ciliary nerves and long ciliary arteries will be seen passing forward, between the sclerotic und choroid, to the iris ) The choroid is a thin, dark-coloured membrane spread over the inner face of the sclerotic, whose general conformation it repeats. It is divided into two zones by the ora serrata—a denticulated line which corresponds to the point where the retina changes its characters, Posterior or choroid zone.—Throughout the extent of this zone the choroid is uniformly thin, and corresponds, by its ewternal face, to the sclerotic ; by its internal face, it is in contact with the retina, but does not adhere to it. Posteriorly, it shows an opening through which the optic nerve passes. In front, at the anterior opening of the sclerotic, it is continuous with the anterior zone. The inner face of the choroid is not uniform in colour, being perfectly black in the lower part of the eye; this is abruptly terminated at a horizontal line that passes about the 8th or 9th part of an inch above the — optic papilla. From this line, on the segment of a circle from 4, to 7%; of an inch in height, it shows most brilliant colours: at first blue, then an azure-blue, afterwards a brownish-blue, and after this the remainder of the eye is occupied by an intense black. The bright portion is the tapetum. Anterior or ciliary zone. This includes two parts: the “ ciliary circle —— “oe ea SE ee THE EYE. 821 ( et) and the “ciliary body.” The ciliary cirele, ligament, or muscle (annulus albidus) varies in width from one to two millimétres; its face adheres closely to the sclerotic, and its internal is confounded with the ciliary body; the posterior border is continuous with the choroid zone, near the canal of Fontana (ciliary canal). The anterior border gives attachment to the greater circumference of the iris. Its structure and uses will be referred to hereafter. The ciliary body (corpus ciliare) forms a kind of zone or ring, wider than the cili ligament, and consequently overlaps the latter before and behind. It extends, on one side, on the inner face of the choroid, and on the other, on the posterior face of the iris. When the cornea and sclerotic are removed so as to expose the ciliary ligament, this zone is not seen; and to discover it, it is necessary to excise all the posterior part of the shell of the eye by a circular incision, and evacuate the vitreous humour. We then observe, around the crystalline lens, a wide, black circle, forming very regular radiating folds (ciliary processes) projecting inwards by their inner extremities, and appearing in the posterior chamber of the eye, after cutting away the iris; all abut by these extremities on the circumference of the lens, which they do not quite reach, although the latter is sustained by, and “set” in, the middle of the ligament. These radiating folds (Fig. 384, 4) are from 110 to 120 in number in the Horse, and are constituted by little parallel leaves, wider at their inner than their outer extremity; the furrows that separate them posteriorly are partly concealed by the prolongation of the retina that constitutes the zonula of Zinn. ‘The coronet formed by the ciliary processes is usually asymmetrical. (Between the sclerotic, the cornea, and the ciliary ligament, exists a minute circular canal—the ciliary canal, canal of Schlemm, sinus circularis iridis, circulus venosus orbiculi ciliaris, or canal of Fontana, from its discoverer. It is sur- mised to be a venous sinus, as it can always be injected from the arteries.) Srrvcrure.—The choroid zone is com- posed of four superposed layers: 1, The external is formed by a network of con- nective elastic fibres, among which are disseminated a great number of pigment cells; 2, The second layer is constituted by a network of large arteries and veins— the posterior ciliary—and a plexus of nerves (ciliary) accompanied by ganglia and some (stellate) pigment sacs rin Ace are arranged with t regularity in droo ing branches, "ce oa the vasa sortiaias yg aa aig p sopra pee (Pig. 386, 2, 4); these are chiefly on the (HUMAN), SEEN Geter wisn ee outer surface of the layer, the arteries 1, Divided edge of the three tunics, ramifying on the inner surface. ) 3, The sclerotic, choroid (the dark layer), third layer, or tunica Ruyschiana, has for nd retina; 2, Pupil; 3, Iris, the its basis an amorphous substance containing Yes, Ciliary promeralp aepr a network of exceedingly fine capillaries jotina. site Rated LIS (extending to the ciliary processes); 4, The internal layer is composed of hexagonal cells, regularly plaéed one upon the 822 THE APPARATUS OF THE SENSES. other on the surface of a structureless laminm; the cells are provided with a — nucleus, and contain pigment-granules which exclusively occupy their anterior — moiety. (On the choroid this cell formation is single, but on the iris and ciliary — processes there are several layers. A very delicate membrane— membrane of Bruch—has been described as lining the inner surface of the choroid, and retaining the pigment in its place; this membrane may be seen on the posterior surface of the iris, and it probably prevents: Fig. 385. the pigment being removed by the aqueous humour.) — The use of the choroid membrane is to,convert the ocular globe into a veritable darkened chamber. (The $, pigment absorbs the rays of light which pass through ies “zy the retina, and thus prevents their becoming and confusing the vision. The brilliant metallic- coloured layer named the tapetum is more particularly observed in nocturnal animals, and especially in the Carnivora; it is due to the presence of a thick layer of wavy fibrous tissue outside the choroidal ithe. lium. By reflecting the rays of light a second time ao CELLS FROM PIGMENTUM through the retina, it probably enables the animal Rees to see better at night. It is the cause of the glare a, Pigmentary granules concealing the nucleus; Perceived in the eyes of Cats and other creatures in b, The nucleus distinct. the dark.) The ciliary ligament is a contractile body, being composed of unstriped muscular fibres which are arranged in orbicular — fasciculi, or extend backwards (and are lost in the choroid, behind the ciliary processes). These fibres are intermixed in the plexus of ciliary nerves, on whose track small ganglia are formed. By its contractions, the ciliary muscle (or ligament) plays an important part in accommodating the eye to the perception of objects at different distances. (In Birds, the muscular fibres are striped.) The ciliary body or processes are formed by intercrossed fasciculi of con- nective tissue, vessels, and some unstriped fibres; their inner surface is covered by pigment, like that of the choroid zone. 4. The Iris, (Figs. 383 f; 386, 6.) The iris forms in the interior of the eye, at the anterior opening of the sclerotic, and in front of the crystalline lens, a veritable diaphragm pierced with a central opening—the pupil—which contracts or dilates according to the intensity of the light and the distance of the objects to which the vision is directed. This diaphragm divides the space between the cornea and the anterior face of the lens and internal extremities of the ciliary processes, into two compartments or chambers of unequal size: the anterior being the largest, and the posterior having only a virtual existence, the iris being close to the crystalline lens. In shape, the iris is elliptical, like the cornea and the sclerotic aperture. Its anterior face is flat or very slightly convex, and has very marked circular furrows and radiating striw, noticeable only at the outer cir- cumference of the membrane. It is diversely coloured, not only according to species, but also in individuals. In Solipeds, it has nearly always a brownish-yellow hue; though sometimes it is nearly white or bright grey, when the animal is said to be “ wall-eyed.” The posterior face, in relation with the lens and ciliary processes, is th ila i ta te lei lind Sm > Se eee wee THE EYE. 823 covered by a very thick layer of pigment named the uvea: portions of which, supported by a small pedicle, frequently pass through the aperture and appear in the anterior chamber of the eye, where THE EYE (HUMAN) WITH THE SCLEROTIC COAT REMOVED. f 1, Selerotic coat; 2, Veins of the choroid; 3, Ciliary nerves; 4, Veins of the choroid; 5, Ciliary ligament; 6, Iris. they are known as “soot-balls” or corpora nigra. (There are frequently several of these black spongy masses, which are generally attached to the upper border of the pupil; on the lower margin, when present, they are much smaller. Their colour is a brownish-black. They are sometimes so large as to give rise to apprehensions of injury to the vision.) The larger circumference of the iris is attached to the ciliary liga- ment, which unites it to the choroid; it is also related to the margin of the cornea, as well as to that of the’sclerotic opening. The lesser, or internal circum- ference, is elliptical, and circum- scribes the pupillary aperture. Srrvucrure.—The organisation of the iris has been much dis- cussed; but at present it is ad- mitted that its principal element is unstriped muscular fibre. A proper membrane and two epi- thelial layers enter into its form- ation. The proper membrane has, for its framework, circular or radia- ting fasciculi of wavy connective tissue, with pigment cells. Be- tween the fasciculi are placed the unstriped fibres; these are disposed in a circular manner around the Fig. 387. MUSCULAR STRUCTURE OF THE IRIS OF A WHITE RABBIT. a, a of the pupil ; 6, 6, Radiating fasciculi of dilator muscle; co, c, Connective tissue with its corpuscles, pupil to constitute the pupillary sphincter, and others radiate from the lesser 824 THE APPARATUS OF THE SENSES. circumference towards the ciliary ligament to form the dilator of the pusibed The very fine radiating vessels are disseminated among these fibres, and pass to the anterior ciliary trunks. The nerves supplied to the iris are from the ciliary plexus. The anterior epithelial layer is composed of the polygonal cells of the aqueous-humour membrane, already described as existing on the posterior surface of the cornea. The posterior epithelial layer, or wvea, is éonatituted by pigment cells analogous to those of the choroid, but less regular in shape. In the foetus, the pupil is closed by a very thin transparent membrane— the membrana pupillaris. (It is identical’ with the anterior layer of the capsule of the crystalline lens.) b. The Retina. (Fig. 883, d.) (Preparation.—The choroid must be removed under water by means of forceps and scissors, after the lens and vitreous humour have been evacuated. A good view of the retina is to be had by looking through the vitreous humour, after the leus and iris have been excised from an eye ) : The retina, the essential portion of the eye, considered as the terminal expansion of the optic nerve, extends over the internal face of the choroid, from which it is easily separated, and lies between that membrane and the vitreous humour. On arriving at the ciliary body, it is exactly moulded on the radiating folds of its posterior face, and with them is prolonged to the eircumference of the crystalline lens, on the capsule of which it appears t0) become lost, after being closely united to it. It also adheres so firmly to. the ciliary processes that, in the fresh eye, it is impossible to detach it. When the eye has been kept some time, however, the two are easily separated; the cornea is removed with a portion of the sclerotic; then dividing the iris into several pieces by diverging incisions, each is turned outwards by a slight traction that ruptures the ciliary zone and the choroid; the retina being thus divested of the parts which cover it anteriorly, is seen to form around the lens a kind of Elizabethan ruff, dovetailing with. the ciliary processes. This plaited collar has been named the zonula of Zinn (zonula ciliaris, and ora serrata). The majority of anatomists, through having neglected to study this part in fresh eyes, con wrongly considered it as distinct from the retina. $Y At the point where the optic nerve enters the eye, there is found on the retina a small oval elevation, whose larger axis is about } inch; this little prominence is the optic papilla or punctum caecum (papilla conica). From, its.centre emerge the vessels of the retina. 4 Srrvcture.—The retina is the most important of the three tunics of the eye, and it is also the thinnest and most delicate. It forms a soft, pulpy, transparent expansion when quite fresh, but is white and opalescent soon after death. It is composed of connective tissue and nerve elements, which are arranged to form nine or ten superposed layers. Connective Tissuz—This is very delicate and nucleated, and forms two thin lamine named the external and internal limitary membranes ; these’ are connected by radiating fibres which pass through the nerve elements; and anastomose very closely in the molecular layer. Nerve Exements.—These are distributed in seven layers, which prespails the following characters : ; 1. Layer of rods and cones. (Fig, 388, 1.)—This is also termed the mem- THE EYE. 825 brana Jacobi (bacillary or columnar layer). It is situated between the inner face of the choroid and the external limitary membrane. Rods and cones, regularly mixed, make up its structure. Each of these comprises two portions or segments (separated by a bright transverse line). The outer segment (or shaft) is brilliant and refractive, and consists of a small stalk termi- Pig. S08: nating in a point for the cones; with a shorter - stalk than the inner segment for the latter, and equal in length to this segment for the rods. The inner segment is a small granular shaft for the rods, and an enlargement whose base is towards the centre of the eye for the cones. The elements of this layer quickly alter after death. 2. External granular layer (2).—This is comprised between the external limitary and the intermediate membrane. It is formed by the granulations of the cones and those of the rods: small oval nucleated cells, furnished with an external prolongation that joins them to the base of the cones and rods, and an ex- ternal varicose prolongation which often en- on arriving at the intermediate layer. 3. Intermediate layer (3).—This is very thin, and composed of flexuous fibrille, which are connected with the adjoining elements. 4. Inner granular layer (4).—In this we find cells whose membrane is in contact with the nucleus; these cells have minute prolong- | 5». .ij)ar Jayer: 2, Outer cranu- ments analogous to those of the external ” larlayer; 3, Intermediate fibrous granular layer, and which connects them with layer; 4, Inner granular layer; the surrounding layers. 5, Finely-granular grey layer ; 5. Molecular layer (5).—One of the thickest, ©, ver ofnerve-cells; 7, Mayer . . s of optic nerve; 8, Limi- this layer (the grey vesicular) presents a tary membrane. granulous aspect; in its mass, the connective : tissue forms a close mesh, in the midst of which are seen fine fibrillew passing in every direction. 6. Ganglionic layer (6).—This is composed of a single stratum of ramified nerve-cells, whose prolongations pass into the molecular layer, where they join the filaments of the next layer. 7. Layer of optic-nerve fibres (7).—The fibres (ultimate fibrils) of the optic nerve, in passing through the sclerotic and choroid, anastomose with each other, and arrange themselves in a cone shape, whose apex corresponds to the papilla conica; at this point they suddenly spread out in every direction, between the ganglionic layer and the limitary membrane. To sum up, the retina comprises the following layers, reckoning from before to behind: 1, Internal limitary membrane; 2, Layer of optic-nerve fibres; 3, Layer of nerve-cells; 4, Molecular layer; 5, Inner granular layer; 6, Intermediate granule layer; 7, Outer granular layer; 8, Outer limitary membrane; 9, Columnar layer; 10, Pigmentary layer of the choroid, if this be attached to the retina, as Schultze proposes. It is to be remarked, that at the ora serrata all the nerve elements of the retina disappear, and the membrane, reduced to its connective tissue, is VERTICAL STCTION OF RETINA, 826 THE APPARATUS OF THE SENSES. continuous with the posterior face of the ciliary processes, where it afterwards forms the zonula of Zinn. Fig. 389. DIAGRAM OF THE STRUC- TURE OF THE RETINA. p, Pigment cell of the retina connected with a rod; m, Cone seated on the membrana limitans externa, the inner seg- ment containing a cone ellipsoid, and a needle; m, f, Proper fibre con- necting rod and cone with one of the cells of the membrana fenestra, whose cells are in com- munication with the membrana limitans in- terna, m, I, i, by means of a thick radial fibre with an oval nucleus attached; g, g, Multi- polar ganglion of nerve elements; 0, p, Optic fibrilla ; g, r, i, Supposed connection of the nucleus with prolongation of a ganglion cell, (At the papilla conica, all the other elements than the nerve-fibres are entirely absent; hence this is presumed to be a * blind spot.”) Blood-vessels.—The retina possesses a par- ticular vascular distri- bution. The arteria centralis retine, with its vein, enters the optic nerve at ashort distance from the globe, and with it passes into the eye; they traverse the papilla, and immediate- ly divide into two branches, one of which is directed upwards, the other downwards. Close and fine anastomoses unite the vessels of the retina with the ciliary vessels at the back of the sclerotic. Fig. 390. CAPILLARIES IN THE VASCULAR LAYER OF THE RETINA. THE MEDIA OF THE EYE. The Crystalline Lens, (Fig. 383, 7.) The lens, as its name implies, is a (solid) trans- parent body, sustained at the smaller circumference of the zone formed by the ciliary processes (behind the pupil, and partially imbedded in the vitreous humour). It is biconvex in shape, and flatter on its anterior than its posterior surface. We have mea- sured the lens of the Horse’s eye, and find the follow- ing dimensions: vertical diameter ,%;ths, and trans- verse diameter }°,ths of an inch. The posterior face is evidently more convex than the anterior, for we found the transverse diameter of the last to be ;4;ths, and that of the first ,3,ths of an inch. Srrvcture.—The lens is enveloped in a trans- parent membrane, the capsule, which contracts no adhesions with it. Its thickness is uniform in the Horse, and its tissue is slightly striated transversely ; its internal face is lined by a layer of pavement epithelium, The proper tissue of the lens is disposed in concentric layers, which the microscope proves to be composed of fibres; the outer layers are almost fluid (gelatinous), but their consistence gradually increases towards the centre. Between the proper tissue and the epithelium of the capsule are two or three layers of round cells, whose dissolution some time after death forms the liquor Morgagni—which is consequently nothing more than the result of a cadaveric phenomenon. f (The capsule of the lens is composed of tissue exactly similar to the THE EYE, 827 elastic layer of the cornea. To examine the structure of the lens, it is best to boil it, or to immerse it in alcohol or nitric acid, which renders it hard and opaque. It is then found to be divided into three equal parts by three lines, which radiate from the centre to within one-third of the circumference ; so that each of these portions is composed of hundreds of concentric layers, within one another, like the coats of an onion. According to iker, these fibres are tubular, and contain an albuminous fluid. If any single layer is examined with the microscope, it is found to be made up of these parallel fibres, which measure about »,5,th of an inch in thick- ness, and are united with each other by finely serrated or scalloped borders that dovetail in the most beautiful manner. The lens is nourished by means of the extremely delicate layer of nucleated cells on its surface, which absorb nutriment from the capsule.) The lens receives neither vessels nor nerves. In the foetus, the arteria centralis gives off a branch which passes forward through the vitreous humour, and enters the posterior face of the lens ; but this vessel disappears long before birth. (The use of the lens is to bring the rays of light to a focus upon the retina, they being greatly refracted in passing through it.) 2. The Vitreous Humour. (Fig. 383, 1.) The vitreous body, or humour, occupies all the cavity of the eye behind the lens (about two-thirds of the interior of the eye). It is a kind of colourless, transparent jelly, much more fluid than the lens, and entirely amorphous, according to Ch. Robin ; though the majority of anatomists add some embryonic cells. At the surface of the vitreous mass is a very thin structure, the hyaloid membrane, which is in contact, externally, with the retina and the posterior face of the lens. (This hyaloid membrane forms cells, in which the watery fluid consti- tuting the humour is contained; the cells communicate freely, and are rendered apparent by freezing the eye or steeping it in chromic acid, when it is found that the humour is intersected by a large number of delicate partitions, with a cylindrical space in the axis for the passage of the central artery in the foetus. The membrane is firmer on the surface than else- where, so that it serves as a capsule for the humour, and suffices to keep it in shape after the outer envelopes of the eye are removed. As mentioned, the lens is maintained in situ by the zone of Zinn.) There has been described around the lens, between the hyaloid membrane and the zone of Zinn a circular passage named the canal godronne (canal of Petit), because of its form. I look upon this canal as an artificial production, and due to the means employed to demonstrate it in mankind and animals. (This humour concurs in refracting the rays of light.) 8. The Aqueous Humour. This is a liquid that owes its name to its great fluidity; it is contained in the anterior and posterior chambers of the eye, in front of the lens. It is secreted by a particular membrane, the membrane of the aqueous humour, or membrane of Descemet or Demours; this is an extremely thin serous layer, easily distinguished on the posterior face of the cornea, and admitted to exist on the two faces of the iris, the ciliary processes, and anterior face of the eapsule of the lens, where it is reduced to epithelium only, 828 THE APPARATUS OF THE SENSES. (The chief function of this humour appears to be to maintain the con- vexity of the cornea, and to facilitate the movements of the iris and lens; as well as to assist, to some extent, in refracting the light that passes through it to the lens and retina. The rapidity with which this fluid can be regenerated is very striking; absorption also takes place very rapidly in the anterior chamber of the eye. The frequency of adhesions between the iris and lens, after attacks of ophthalmia, is accounted for by the small quantity of this fluid that exists between them, as owing to the smallness of the posterior chamber this is reduced to a mere film.) Arricte IT.—Accrssory OrGANS oF THE VISUAL APPARATUS. ORBITAL CAVITY. Situated at the side of the head, at the point corresponding to the union of the cranium and face, the orbital cavity is circumscribed by a bony margin, in the formation of which the orbital process, frontal, lachrymal, malar, and a small portion of the zygomatic process of the temporal bone, concur. Posteriorly, however, there are no bony walls, and the cavity, in the skeleton, is confounded with the temporal fossa. A fibrous membrane completes this cavity in the domesticated animals, and keeps it distinct from the fossa. Designated the ocular sheath (ocular membrane or periorbita), this fibrous structure is attached, posteriorly, to the border of the orbital hiatus, and anteriorly to the inner face of the orbit; being prolonged beyond the external lip of this osseons rim to form the fibrous membrane of the eyelids. Strong externally, the ocular sheath is thin within the cavity. It is traversed by vessels and nerves, and is composed of a mixture of elastic and inelastic fibres. (Unstriped muscular fibres have also been described as existing in this orbital periosteum. Thus completed, the orbital cavity has the form of a regular hollow cone, open at its base, and closed at the apex, which corresponds to the orbital hiatus. In the ordinary position of the head, the opening of this cone is directed forwards, downwards, and outwards. Independently of the globe of the eye, this cavity lodges the muscles that move it, the membrana nictitans, and the lachrymal gland. MUSCLES OF THE EYE. (Fig. 391.) These are seven in number: five termed recti muscles, and distinguished as posterior, superior, inferior, external, and internal; two named oblique—a large and small, (Preparation.—Detach the eyelids from the margin of the orbit, cutting away the lower, but leaving the upper. Saw through the zygomatic process of the temporal bone, in front of the temporo-maxillary articulation, also through the temporal process of the zygo- maticus, and the base of the orbital process of the froutal bone; remove the excised piece of bone, and the temporal fossa and ocular sheath are exposed. Cutting through the latter, the muscles of the eye are seen disposed in a conical manner around the globe; dissect away the fat lodged among them, in order to isolate them.) 1. Posterior Recrus Muscux (or retractor oculi).—This muscle com- pletely envelops the extra-cranial portion of the optic nerve, being a muscular sheath resembling in shape the fibrous lining of the orbit. Its fibres are disposed longitudinally, arise around the optic foramen, and are — tage in Birds, they are striped. (In the Oz, its anterior face has a brighter colour than in the Horse. In the Sheep it is a brownish-yellow; in the Goat blue.) In the Dog its colour is a more or less bright golden-yellow; in the adult Cat green; and young animuls a briglit blue. ‘The pupil is elliptical in the Ox, as in Solipeds (in the Sheep and Goat it is more elongated); in the Dog it is circular, and, when very much late, it is the same in the Cat; but, when contracted, it becomes elliptical vertically, may be so nurrow as to represent nothing more than a thin perpendicular slit. (Iu the Pig it is round.) There are no differences worthy of note in the other parts of the eye. Acorssory OrGcans or THE VisvaL Arparatrs.—The motor organs are nearly the same in all the other animals. Bu 2 / Vv “a 836 THE APPARATUS OF THE SENSES. (The posterior rectus, or retractor muscle, is most developed in Ruminants, whic during their whole time of feeding, have the head in a dependent position. In most of the Carnivora, instead of this muscle forming a complete hollow cone, as in Ruminants, there are four distinct strips, almost resembling a +econd set of recti muscles, but deep- — reated, and inserted into the posterior, instead of the anterior, portion of the globe.) = Muscles.—Birds have only six muscles: four recti, and two oblique. The arise from the anterior wall of the orbit; consequently, the great oblique does not pass through a pulley. : i wn Eyelids.—The disposition of these is the same in all mammifers. In Birds, the lower lid is the largest, and is furnished with a particular depressor muscle; there are no Meibomian glands. There is a third eyelid, corresponding to the membrana nictitans of quadrupeds ; it is sufficiently extensive to cover the entire front of the eye. 1 a ll Glands.—In Ruminants, the Pig, and in Birds, there is found, annexed to the mem- brana nictitans, Harder’s gland—a conglomerate gland, with adi epithelium in mammifers, and cylindrical and granular in Birds It secretes a thick white matter, which is thrown out on the membrana by one or two orifices. Its use is, doubtless, to — favour the movements of that organ over the surface of the eye, as well as those of the eyelids. (In the Oz, this gland and its ducts are large. The Inchrymal gland is also voluminous and its nasal opening is situated higher in the nostril than with the Horse. In the Sheep, there are found, ner the lachrymal fossa, several adipose follicles which do not properly belong to this apparatus, and which secrete a consistent, unctuous, yellow matter. In the Pig, the lachrymal ducts are separated, by a bony partition’ into two sets, as far as the lachrymal sac.) . (Orbital cavity—In Ruminants, the frontal and superior extremity of the maxillary — bones contribute largely to the formation of this cavity. In the Pig, the up of the orbit is not completed by the orbital process of the frontal bone, which is short; it is continued by a ligament. In the Dog, the superior portion of the cavity is entirely — formed by a ligament, which replaces the orbital arch; in the Cat, this ligament is smaller, and the orbital process of the zygomatic concurs with tl.at of the frontal bone — to form the upper wall.) ; ~@ COMPARISON OF THE VISUAL APPARATUS OF MAN WITH THAT OF ANIMALS, EssENTIAL OrGAN oF Viston.—The eyeball of Man is almost spherical, as in the Carnivora. The sclerotic does not differ much. The cornea has two limitary membranes, and is much less elliptical than in Solipeds. The choroid has the same zones as in animals; it is uniformly brown. The ciliary processes, seventy to eighty in number, are a little longer than in the Horse, and do not exceed, in front, the ciliary ligament, tothe — inner face of which they adhere throughout their external border. The pupillary open of the iris is always round. The retina is the same in structure as y A little above the optic papilla, there is a circular or oval patch, about j; of anineh in diameter, in the centre of which is a transparent spot; this is the yellow spot (macula lutea), with the fossa centralis of the retina (fovea ceeds fone of Soemmering). At this patch, the tissue of the retina is slightly modified, especially at the fossa; there are only cones in the columnar layer, and «ll the other layers wipe to be con- founded into one granular mass. (This spot only exists in animals which have the axes of the eyeballs parallel with each other, as in Man, the Quadrumana, and some saurian =” reptiles.) There is nothing particular in the aqueous humour, lens, or vitreous humour. Accessory OrGANS oF THE VisvaL Apparatus.—The orbital eavity of Man is entirely inclosed by bony walls, and there is no fibrous sheath. (A fold of the orbital fascia has been described as separating the eye from its surrounding adipose tissue, and which, like a “ tunica vaginalis,” enables the globe to roll with rapidity and precision.) The muscles are six in number—four recti, and two oblique; the Ee oblique is the same as in «nimals, Only the rudiment of a caruneu/a lachrymalis is present. The nasal duct opens at some distance up on the surface of the inferior meatus, = ee (C, THE INTERNAL KAR OR LABYRINTH. 837 CHAPTER V. AUDITORY APPARATUS, ‘Tne sense of hearing, destined for the perception of sounds produced by the vibration of bodies, has for essential agents the auditory or eighth pair of ; ie nerves, whose terminal fibrille ramify in the membranous walls of a system of cavities forming the internal ear ; these cavities are excavated in the substance of the petrous bone, and communicate, externally, by means of two other systems of diverticuli, which constitute the middle and external ear. ARTICLE L—Inrerwat Ear, on Lapyrintu. ( im.—The dissection of this part, from its minuteness and complexity, as well as the density of the bone surrounding it, cannot be made with advantage by the student. He is, therefore, recommended to study it in special preparations, and in the following description.) : The cavities which, together, compose this part of the auditory apparatus, being entirely channeled within the petrous portion of the temporal bone, have their walls, forming the osseous labyrinth, constituted by that bone. contain the soft parts, named*the membranous labyrinth, and fluids ot ph). THE OSSEOUS LABYRINTH. This is composed of three portions: the vestibule, semicircular canals, and 1. The Vestibule. This is a small, somewhat oval cavity, in the centre of the bone, and out- side the perforated bony plate that forms the bottom of the internal auditory hiatus. It is areal vestibule, with regard to the other parts of the labyrinth, which all open into it. On its external wall is the fenestra ovalis (fenestra vestibuli), an opening closed by the stapes. The inner shows the foramina through which the filaments of the vestibular branch of the acoustic nerve pass. Below, and in Sront, is a large orifice, the commencement of the scala cochlew; above, are five little apertures, the openings of the semicircular canals. 2. The Semicireular Canals. Three in number, and very narrow, these canals owe their name to their form. They are placed above the vestibule, like three semicircular arches united in a triangular manner at their base, and are distinguished as superior or anterior, posterior, and exlernal. The first two open together, by their - adjacent extremities, into the vestibule; consequently, there are only five orifices of the semicircular canals in this cavity ; in addition, the adjoining ings of the posterior and external canals are so close to each other, that they appear to be sometimes united at the bottom of a short common 3. The Cochlea. Situated external to, and below the vestibule, at the inner wall of the cavity of the tympanum, the snail-shell or cochlea is well named, as it presents exactly the form of certain molluscs’ shells, It is a spiral conical canal, / ux — ‘7 ™ 838 THE APPARATUS OF THE SENSES, twisting downwards, forwards, and upwards, around a central conical (the modiolus) ; so that its centre nearly corresponds to the inner wall of the — tympanum. DIFFERENTIAL CHARACTERS IN THE AUDITORY APPARATUS OF OTHER THAN SOLIPED — ANIMALS. r There are no notable differences in the internal ear. a In the middle ear, there are some modifications, either in the bones or 8 In Ruminants, the auditory bones are like those of the Horse, except that the ha = the malleus is more curved, and the body of the ineus is longer. In the Dog, the h har lo of the malleus is covered with small, pointed processes, and the branches of the stapes | long and thick. In the Pig, the branches of the latter are slight and inflected, and the base is wide and thin: in a word, the s of this animal bears no resemblance to « stirrup; the malleus is very much tibflscted trvierdae In the last two animals, no osseous nucleus is found in the tendon of the stapedian muscle. It is needless to say that the fenestra ovalis varies with the base of the stapes, (The absence of the mastoid cells in the Sheep and Goat has been already noted.) The Eustachian tube exists in all the animals, but the eustaeel pouches are only ; found in Solipeds. — In the external ear, the conchal cartilage varies much in shape. It is thin, inclined © outwards, and widely opened in Ruminants, In the Pig, it differs a little, according to breed, though it is always much developed, sometimes erect, but most uentl drooping. It is always short, pointed, erect, and open in front, in the Cat. (In this animal a small duplicature of the external margin of the concha is ‘often seen.) In Birds, — the external ear is limited to the auditory canal. (The differences in the muscular arrangement have been noted elsewhere.) COMPARISON: BETWEEN THE AUDITORY APPARATUS IN MAN AND THAT OF ANIMALS. There is nothing to be said regarding the internal ear. The middle ear comprises _ the same parts as that of mammifers other than Solipeds. The handle of the sallenee straighter, the incus more voluminous, and the stapes thinner, proportionately, a animals. There is no bony nucleus in the stapedian muscle, The muscle of the malleus — is lodged in a distinct canal belonging to the tachian tube The external ear is composed of only two cartilages : one, forming the base of be concha, represents that cartilage in animals; the other, belonging to the auditory resembles the annular cartilage in the Horse. The concha is very irregular in shape, stands at an angle of from 15° to 45° from the temporal bone; it is convex superiorly, and terminates inferiorly by a small lobe. On its anterior face it presents prominences and depressions; the former are four in number: the helix, a fold encire the ear behind and above; the antihelix, a concentric prominence, almost parallel with the preceding; the tragus, a triangular, pointed process, covered with hair, situated in front of the auditory canal (meatus); the antitragus, opposite the tragns, behind the canal, “ and above the lobule. The depressions are: the concha, a wide cavity, limited by the antihelix ; the seaphoid fossa (fossa innominata) situated above the latter; and the see triangularis comprised between the helix and antihelix. The pavilion of the ear is traversed by several muscular fasciculi, which can have no influence on its movements. The concha has also extrinsic museles—the anterior auri- ~ eularis (attrahens aurem\, auricularis superioris (attolens aurem), and the . posteriores (retrahens aurem). The action of these on the concha is very slight. a | | Tad i [ 851 ] BOOK VIII. GENERATIVE APPARATUS. Inprvipvats in the organic kingdom possess the faculty of reproduction, and thus perpetuate the species to which they belong: a grand and beautiful law of the vital force, which holds under its care the preservation of the organised world. In mammifers, the generation of a new being demands the concurrence of two individuals—a male and female—who have inter- course under certain determinate circumstances. The female furnishes a onthe ovum, and the male a fertilizing fluid—the semen, which vivifies ovum, and renders it capable of development. We have, therefore, to study separately the generative, or genital organs of the male, and those of the female. CHAPTER I. GENITAL ORGANS OF THE MALE. Tue semen is elaborated in the structure of the two festicles : lobular glands, each of which is provided with an excretory duct, doubled a great number _of times on itself at its commencement, to form the epididymis, and destitute of sinuosities for the remainder of its extent, which is named the deferent canal (vas deferens). ‘This canal carries the fecundating fluid into the vesiculee seminales, reservoirs with contractile walls, where it accumulates, and whence it is expelled during copulation by passing through the ejaculatory canals (or ducts), and the urethral canal. The latter is a single canal common to the two apparatus of generation and urinary depuration ; it is provided in its course with three accessory glands— the prostate, and 8 glands, and is supported by an erectile stalk, the corpus cavernosum, _ with which it forms an elongated organ, the penis, which, in the act of copulation, is introduced into the vagina, to the bottom of which it carries the tic fluid. as e will successively consider the secrelory organs or testicles, and the - exeretory apparatus, comprising all the other organs. THE TESTICLES, OR SECRETORY ORGANS OF THE SEMEN, The testicles (testes) are two glands suspended on each side of the pines, between the thighs, where each occupies a particular serous pouch, the vaginal sheath (tunica vaginalis). We will commence by describing this cavity, and afterwards the organ it contains. ite I $52 THE GENERATIVE APPARATUS, 1. Tunica Vaginalis. The tunica vaginalis, in the domesticated animals, is only a diverticulum of the abdominal cavity, the serous membrane of which—the peritoneuam— becomes a hernia in the inguinal canal, passing through the upper (internal) inguinal ring, and prolonged below the inferior (external) ring, so as to form a serous sac, which is enveloped by membranous walls. We have to study, in the vaginal sheath: 1, Its interior; 2, The — enveloping membranes which form the external walls, and to which we give the common name of scrotum. Interior.—The serous sac constituting the tunica vaginalis, is vertically elongated, and slightly inclined downwards, inwards, and backwards. Its inferior extremity, forming the bottom, or cul-de-sac, is pear-shaped, and lodges the testicle and its epididymis. Its middle portion, contracted into a narrow canal, contains the spermatic cord. The superior extremity, or entrance, is open, to maintain communication with the abdominal cavity; through it pass the spermatic vessels and vas deferens. As has been said, the peritoneum forms the vaginal sac. As in the abdomen, it is divisible into two layers—parietal and visceral. The latter tunica vaginalis propria) covers the testicle and the cord ; while the former are vaginalis communis, or reflexa) lines the innermost of the membranous coverings which serve as a wall to the tunica vaginalis. These two layers are made continuous by a serous frenum, analogous to the mesentery which sustains the floating colon ; like it, it is formed by the junction of the two layers. Flat, elongated from above to below, and extending vertically from one end of the sheath to the other, this frenum is attached, by its upper border, behind the spermatic cord; its lower extremity passes over the epididymis, and from it on to the testicle; above, it is continued into the abdominal cavity, in accompanying the different canals composing the cord. — (A small quantity of serous fluid is usually present in the tunica ginalis. When in excess it gives rise to hydrocele. Envetorine Mempranes.—The stratified layers that form the external walls of the vaginal sheath, and which are generally described in anatomical treatises, with the two serous layers, as the envelopes of the testicle, are four in number. Reckoning them from within to without, they are the fibrous tunic, cremaster muscle, dartos, and scrotum. Frsrous Tunic (infundibuliform fascia).—This forms the most complete covering to the tunica vaginalis, extending, as it does, over the whole surface of the parietal serous layer, to which it is closely adherent. Very thin, especially at the points corresponding to the cremaster, this membrane is continuous, around the upper inguinal ring, with the transversalis fascia, of which it is only a dependency ; its external face is in relation with the cremaster and dartos. Cremaster.—This muscle is usually described as an envelope of the testicle, by the name of tunica erythroides. In the domesticated animals, it is a bright-red band, attached, above, to the inner or peritoneal surface of the ilio-lumbar aponeurosis; it descends into the inguinal canal, envelops outwardly only the middle portion of the sheath of the testicle, and expands below on the cul-de-sac, where its fibres terminate by small tendons, which are inserted into the external surface of the fibrous tunic. Therefore it is that the envelope the cremaster forms is very incomplete, the greater portion of the testicle, and the inner side of the cord, being left unprotected by this muscular tunic. It is in relation, inwardly, with the fibrous membrane, to THE MALE GENITAL ORGANS. 853 c which it is united by a plentiful cellular tissue; externally, it responds to the ior wall of the inguinal canal and the dartos. t is the contraction of the cremaster that causes the sudden ascent of the testicle. Dantos.—The tissue composing this tunic is contractile; it is con- stituted by a mixture of elastic and unstriped muscular fibres. The dartoic tunic does not reach the inguinal canal; consequently, it does not cover that part of the tunica vaginalis. It forms a pouch below the inguinal ring, and is spread from around the margin of this on to the neighouring parts, to which it adheres somewhat closely ; it is prolonged, gradually thinning, into the sheath of, and even 6n to the penis itself, and to the tunica abdominalis, as well as between the thighs. The two pouches it forms are quite in- dependent of each other, never becoming confounded, though placed in contact on the mesial line to form a double partition (septum scroti), whose leaves are separated above for the passage of the penis. The dartos is in relation, inwardly, with the fibrous and erythroid tunics, from which it is isolated by an abundance of lamellar cellular tissue, which is very condensed towards the globus major epididymis, and forms at this point a kind of cord that passes from the fibrous tunic to the dartos, adhering strongly to each. Externally, the dartos is covered by the scrotum. This tunic determines the vermicular movements of which the scrotum’ is the seat. Scrotum.—The different membranes enumerated above are double, one being for each tunica vaginalis; but the scrotum constitutes a single pouch, enveloping the two testicles at the same time. It is merely the portion of skin covering this region, and is thin, and so closely adherent to the dartos, that it can only with difficulty be separated from it. It is covered by very short fine hair, and the extremely numerous sebaceous follicles in its texture secrete an unctuous matter that renders its surface soft to the touch. (There are also numerous sudoriparous glands, and these, with the sebaceous glands, keep the skin soft and pliable, and modify the effects of friction during progression. On its surface it shows a raphé or seam in the middle, which is a trace of its primary division, and corresponds to the median septum separating the testicles.) 2. The Testicles, (Figs. 397, 398, 401.) External Conformation.—Each testicle is oval in shape, flattened on both sides, lodged in the cul-de-sac of the tunica vaginalis,’ and suspended at the extremity of the spermatic cord. The description of this organ is extremely simple ; it offers for study two faces, two borders, and two extremities. e faces, external and internal are smooth and round. The inferior border is convex and free, like the faces; the superior, almost straight, is related to the epididymis, which adheres to it by its head and tail. Means of Attachment._-The testicle is freely pendent in the lower part of the tunica vaginalis, where it cannot readily be displaced, because of the narrowness of the space containing it. It is suspended, by its upper ' One or both testicles may be retained in the constricted portion of the tunica vaginalis, or remain in the abdomen ; animals in which this occurs are named monorchids or chids. The absence of one or two testicles (anorchidiem) is extremely rare. # of the testicles is the designation applied to these organs when they are found elsewhere than in their ordinary situation. 854 THE GENERATIVE APPARATUS. border, to the testicular or spermatic cord 2 a thick funiculus contained in the - middle portion of the vaginal sheath, and formed by the aggregation of the spermatic vessels with the vas deferens. This cord is itself sustained in the sheath by the frenum that unites the . two serous tunics of that cavity. Srructurr.—Independently of the serous tunic that covers the exterior - of the testicle, there enter into its structure a fibrous membrane, tissue proper, and vessels and nerves. The excretory duct will be studied separately. Fibrous Membrane.—This membrane, designated the tunica i forms a strong resisting shell around the testicle, and its texture is channeled by sinuous spaces which lodge the large spermatic vessels. It is covered by the visceral layer of the tunica vaginalis, to which it closely adheres ; its inner face sends thin septa into the proper substance of the gland, which divide the latter into the spermatic lobules. Towards the upper border of the testicle, and in front, the tunica albuginea is slightly thickened; this part is named the corpus Higmori (or mediastinum testis), and at this point the seminal ducts pass through it to reach the epididymis. (This membrane is dense and inelastic, being composed of white fibrous tissue interlacing in every direction.) - Tissue proper—The proper substance of the testicle resembles a greyish-yellow pulp, contained in the tunic albuginea; it is divided by the prolongations which that tunic sends into its interior into small distinet lobules (lobuli testis), independ- ent of each other. These lobules vary in number, from two to three hundred, and all have the same organisation, each being constituted by two or three extremely convoluted : filiform tubuli, about from one to two yards in length.. These tubes, the tubuli seminiferi, anastomose frequently with each other near their extremi- ties, twine together, and can be unwound like a ball of thread. One of their extremities ter- minates in a cul-de-sac, the other being detached from the lobule, and enters a central A TESTICLE (HUMAN) INJECTED WITH MERCURY. system of excretory ducts which a, a, Lobules formed of seminiferous tubes; 6, Rete will be refe to imme- testis ; c, Vasa efferentia ; d, Flexures of the efferent diately. vessels passing into the head, ¢, ¢, of the epididy- mis; f, Body of the epididymis ; 0 Appendix; 2, , When we cut through a tes- Cauda; i, Vas deferens, ticle vertically and lengthways, so as to divide the corpus High- mori into two lateral portions, there is seen in its substance a whitish 1 In surgical anatomy, there is sometimes included in the spermatic cord the middle portion of the tunica vaginalis and all its envelopes—the serous, fibrous, and e tunics. Fig. 397. p { A “ m * Ae —— Seles ean nae Ve ee eee Abe — aes oes a ie el THE MALE GENITAL ORGANS. 855 framework, sometimes not very apparent, which, curving upwards at both extremities, extends from that body to the posterior end of the testicle, . _ where it disappears; from this are given off a large number of fibrille (trabeculee testis), which diverge in all directions. A mercurial injection by the vas deferens, shows that this part of the testicle is chiefly formed ‘by a ramifying system of rectilinear canals with very thin walls, which open into each other, and unite, on reaching the corpus Highmori, into about twenty principal trunks. These are named the straight canaliculi (vasa recta), to distinguish them from the convoluted tubuli; they receive the latter at their exit from tf. lobules, and are surrounded by numerous bloed- vessels and sustained by the fibrous septa of the tunica albuginea, which ee oot towards the point they occupy. At the corpus Highmori, the vasa recta pass through that body, forming in its texture an anasto- mosing network, the rete testis, and are continued into the epididymis as the efferent canals (vasa saben The seminiferous tubes inthe lobules are from ;}, to the ;45 of an inch in diameter. They are composed of a very thin fibrous membrane (firmer than that in the walls of similar gland eanals elsewhere); slightly elastic, and made up of connective tissue with longitudinal nuclei, this mem- brane is lined internally by a —— _ amorphous membrane (basement) au epithelium. The latter almost com- pletely fills the tubuli; near the wall of the canal it is composed of polygonal cells, but towards the centre these in- crease in volume, become circular and transparent, and show several nuclei in various stages of transformation ; finally, in the axes of the tubuli can be perceived spermatozoa and the detritus of the spermatic cells. Vessels and nerves.—The blood is carried to the testicle by the spermatic ‘artery, which is almost exclusively riated to it; this vessel, after describin a great number of very ‘ovGuES DEL remarkable flexions, enters the am VERTICAL SECTION OF THE TESTICLE border of the gland, a little d (Horse's), PASSING THROUGH THE CoRPU the epididymis. It does not imme- ee Fig. 398. diately plunge into tts substance how 1, Spermatic cord, with its serous covering ; ever, but passes within the texture of the tunica albuginea, along the borders of the testicle, and forms a complete cirele around it. From this circle it sends off divisions, which spread over the sides of the organ, detaching fine arterial ramifications that penetrate its 2, Sections of the flexuous vessels of the cord ; 3, Head of the epididymis, or globus major; 4, Tail of the epididymis, or globus minor; 5, Vas deferens; 6, Corpus High- mori; 7, Rete testis; 8, Tunica albuginea eg. prolongations from its inner face, and which divide the testicle into lobules ; 9, Surface of the tunica albuginea, tissue in accompanying the interlobular septa. (There is generally ibed a tunica vasculosa that forms one of the coverings of the testicle. 856 THE GENERATIVE APPARATUS. “ = This, in reality, is not a distinct coat, but merely the fine ramifications of the spermatic artery spreading beneath the tunica albuginea, and held together by delicate cellular tissue.) , The veins are very voluminous and frequently varicose, and comport themselves like the arteries ; they unite in a single trunk that enters the posterior vena cava, near the renal veins, (On the cord, in addition to their sometimes varicose condition, the spermatic veins have been observed to form a network, named the pampiniform — BO: The lymphatics are most numerous beneath the serous layer and the tunica albuginea. They commence in the lacunw between theseminal tubes __ and vessels, and terminate in the sublumbar glands, The nerves of the testicle are derived from the sympathetic (and pass from the abdomen with the blood-vessels); they form a small particular plexus around the artery. (The nerves pierce the membrana propria of the tubuli seminiferi, and end in a more or less pyramidal mass of protoplasm, in which lie clear elliptical nuclei, The ends of the fibres, therefore, lie in close proximity to the outer layer of secreting cells.) DrveELormEnT.—In the foetus, at an early age, the testicle floats in the abdominal cavity, being suspended from the sublumbar region, near the flank, by a wide peritoneal fold, at the anterior border of which are the spermatic vessels (Fig. 399, e.); the tunica vaginalis is not yet present. The mechanism of the formation of this is very simple, and easy to understand. The visceral layer of the tunica vaginalis, which envelops the testicle and the cord, being already formed, as well as the serous frenum that establishes continuity between this and the parietal layer in the adult animal, it only remains to explain how nature proceeds to construct the vaginal sac in which the gland is afterwards contained. We have remarked, that to the posterior extremity of the testicle is attached a thick round funicle, the other end of which passes into the upper inguinal ring, being enveloped by the peritoneum, and fixed to the posterior border of the serous layer that suspends the testicle. This funicle is the gubernaculum testis, and is continuous, by its inguinal extremity, with the dartos, whose structure it apparently shares, and which alone acts as the scrotal sac to it. The serous layer covering it has on its outer adherent face the cremaster muscle, which is attached to the ilio-lumbar aponeurosis in the vicinity of the inguinal ring, enters the serous tube formed by the peritoneal envelope of the gubernaculum, and advances by its terminal extremity to near the testicle. 'To this organ is due the principal share in the formation of the vaginal pouch. When the progress of development in the foetus pushes the testicle towards the inguinal region, the gubernaculum acts as a guide, as its picturesque name sufficiently indicates. It is the first to descend into the inguinal opening, drawing the testicle after it. But in performing this movement it also carries along its peritoneal covering, which ually leaves it to become related, by its adherent face, to the walls of the inguinal canal ; and thus this membrane becomes reflected, just as would a sock everted or turned down from the leg to the foot, the latter being supposed to represent the testicle. The parietal layer of the vaginal sac is, then, nothing more than the serous tube that, in the foetus, enveloped the gubernaculum testis while in the abdomen, and which is reversed on the testicle and cord after their descent into the scrotum, the cremaster muscle on its adherent face having become external. THE MALE GENITAL ORGANS. 857 Tn all species, the descent of the testicle commences before birth: in the Bovide it is even achieved in the early months of intra-uterine existence. In Solipeds, however, the testicle most frequently remains in the inguinal canal until the animal is from six to ten months old. Fig. 399, THE INTERNAL GENITO-URINARY ORGANS, WITH THE STOMACH, LIVER, AND SPLEEN, IN THE FQTUS OF A MARE. R, Left kidney; v, Bladder; 1, Testicle; at, Spermatic artery; G, Gubernaculum testis ; ¢, Epididymus—the letter is placed in the centre of the serous layer which suspends the testicle and spermatic vessels from the sublumbar region, and after the descent of the gland, forms the frenum between the two layers in the vaginal sheath; £, Stomach; F, Liver; /, Lobus Spigelii; p, Vena porte; c, Umbilical cord ; 0, Umbilical vein ; 0’, Intrahepatic course of that vein, indicated by a double dotted line. Funcrioy.—The testicles secrete the spermatic (or seminal) fluid. Pure semen, such as is derived from these glands, is a white, viscid, odorless, 858 THE GENERATIVE APPARATUS, and slightly alkaline fluid. It contains a small quantity of liquid m (liquor seminis), in which is an innumerable mass of spermatozoa, Af the semen has passed through the genital canals, it is made a aqueous by the addition of the fluids secreted by the walls of these e ducts, or by the glands annexed to them. The spermatozoa, zoésperma, spermatozoides, or spermatic filaments, ¢ little elongated bodies from 4}, to x re a line in length. They have pyriform, flattened, or lancet-shaped and a filiform tail te mo. "2 a point; this tail is often furnished at its origin with an enlargement, or unilateral or bilateral ale. Their form is slightly modified during their course through the excretory ducts. (In the different species, ugh possessing certain fixed characters, the spermatozoa yet offer some curious — diversities. Some of these are well exhibited in the annexed represontations of these particles, found in the semen of very dissimilar animals.) The spermatozoa move b pind Fig. 400, undulations of the tail (G: attributes the motion to 1 contractile protoplasm tained in the head). The movements persist for several days in the genital organs of the female ; they are suddenly arrested by water, acids, and — the electric spark ; on the © contrary, they are animated by alkaline fluids. (The — movements cease when the spermatozoa are e toa — temperature of 120° Fahren- heit.) These bodies are de- veloped in the cells of the tubuli seminiferi by a modi- 1, Spermatozoon of the frog; 2, Of the triton; 3, Of camv ata (wedistea pres the finch; 4, Of the field-mouse; 5, Of the hedge- hog; 6, Sheep; a, Head with nucleus ; b, Body ; lution) become round in the — c, Tail. centre of these canals, and ad have from one to ten nuclei; the latter are elongated, and throw out a prolongation that gradually extends and forms the tail of the spermatozoon. When all the nuclei are — thus transformed, the cell-wall ruptures and liberates the spermatozoa, which swim ig in the minute quantity of fluid resulting from the destruction of the ce , EXORETORY APPARATUS OF THE SEMEN. 1. The Epididymis and Deferent Canal, (Figs. 397, 398, 399, 401, 402.) Ermripymis.—The organ thus named commences the excretory canal of the testicle. It is a body elongated from before to behind, placed ‘ae the upper border, and a little to the outside, of the spermatic gland, It has — a middle portion | and two extremities, The middle is contracted, flat on both sides, and free outwardly ; it ig related, inwardly, to the spermatic vessels and the testicle, to which it is- attached by a very short serous layer. The extremities are expanded, and — adhere intimately to the testicle. The anterior, the largest, is named the ’ } | | } THE MALE GENITAL ORGANS. 859 head of the epididymis or globus major. The posterior, the tail of the epidi- dymis, or globus minor, is more detached from the testicle, and is curved to be continued by the deferent canal (vas deferens). Srrvucrure.—The epididymis is constituted by a long duct doubled a great number of times on itself, and whose convolutions, after injection with ‘mereury, can be very readily seen through the serous membrane. This duct results from the union of from twelve to twenty small tubes, the. efferent ducts, which, arising from the rete testis, open together, at a variable ce, into the globus major_ Towards the globus minor there is only one duct, which is more voluminous and less flexuous, and finishes by becoming detached from the posterior lobe of the epididymis to constitute ‘the vas deferens. The organisation of the walls of these ducts is not the same throughout. Thus, in the efferent ducts, it comprises a simple ciliated epithelium, resting on a proper amorphous membrane, which again is placed on unstriped circular fibres attached to a thin fibrous tunic; while beyond, there id observed a stratified ciliated epithelium, a proper membrane, two layers of unstriped fibres—circular and longitudinal—and also a fibrous tunic. The thickness of the muscular layers increases from before to behind. The epididymis receives its arteries and nerves from the same sources as the testicle. Dererent Canat (vas deferens).—This duct is about the thickness of a goose-quill, and is at first flexuous, then ‘straight. It lies parallel with, but behind via cea and to the inner side of, the spermatic vessels, as far as the opening of the tunica vaginalis ; passing through this opening, it enters the pelvic cavity, and crosses obliquely the ureter and obliterated cord of the umbilical artery. -It is then inflected backwards, placed above the bladder, suddenly dilates, and is prolonged as far as the neck of that reservoir, where it terminates; after having penetrated beneath the prostate gland by a sudden contraction, at the origin of which, and outwardly, the vesicula seminalis opens, and is continued by the ejaculatory ducts. The vas deferens is sustained in the tunica vaginalis by a very short serous fold, a dependency of the frenum, whose two lay- . °4) DIAGRAM OF THE TESTICLE ers envelope the spermatic vessels, within (nUMAN). and behind which this duct is situated. In the abdominal cavity, it is fixed by the pro- the rete testis; 2, 2, Trabeculi; longation of this serous duplicature. Its 3, One of the lobules; 4, 4, Vas dilated or pelvic portion is in contact, ect; 5, Globus major ; 6, Globus 1, Mediastinum testis, containing superiorly, with the vesicule seminales, and Ts % Vas deferens, is finally united to its dilated homologue of the opposite side, which it has been gradually approaching, by means of a triangular peritoneal fold, that comprises between its two layers a small club-shaped cavity which will be alluded to again. The calibre of the vas deferens is very small in its vaginal and abdo- minal portions, but is greater towards the pelvic dilatation, where the walls of the duct offer a well-marked areolated disposition. 860 THE GENERATIVE APPARATUS, rf - Srnvcrurs.—The vas deferens is formed, internally, by a very fine mucous membrane covered with cylindrical epithelium, and to this is added, externally, a contractile and a fibrous tunic. contractile layer is formed of three planes of unstriped fibres: the deep and superficial planes have — longitudinal, and the middle circular fibres. It is, proportionately, ry thick at the dilated portion of the duct, and it is to its great density that — the vas deferens owes its consistence as a hard, rigid cord. The mucous membrane of the pelvic dilatation has tubular and acinous glands, ’ 2. The Vesiculee Seminales and Ejaculatory Ducts. (Fig.826) = The vesicule seminales are two oval pouches whose volume varies with — Fig. 402. their contents, and which are placed in the ~ pelvic cavity, above the bladder and the vas _ deferens. Each vesicula has a middle portion — and two extremities. The middle portion is — enveloped by a loose abundant cellu tissue, and is in relation with the rect z above, and below with the bladder and yas — deferens. a. The anterior extremity is the s and forms a rounded cul-de-sac, co in almost the same manner as the bladder by the peritoneum, which at this point fur- nishes a very small triangular frenum (the — recto-vesical fold) that unites the two vesi- cule, The posterior extremity tapers to a — narrow neck, which passes beneath the pros- tate gland, and joins at a very acute angle the terminal extremity of the vas deferens, to constitute the ejaculatory duct. | The walls of this pouch are composed of three membranes: an internal mucous, a middle muscular, and an external ; The mucous layer is continuous with that of the ejaculatory ducts, and is very thin, SUPERIOR VIEW OF THE PELVIC Por- delicate, and follicular. It shows numerous’ cb gd eae cata folds, which disappear with Histanenes the , duct. The middle layer eviden :' GLAND, COWFER'S GLANDS, ANDTHE 1°74 C1oe of mmuseular membranes 4a URETHRA. identity with that of the bladder is complete. 1, Left vas deferens; 1’, Its pelvic At the bottom of the cul-de-sac it gives off ener bPig ry rrp Ve on) several fasciculi, which radiate on the ex- right side ; 3,4, Vesicule seminales ; : . “a The third Tabeyac rpg 6, eS ternal surface of the peritoneum, (In addi- layer uniting the vasa deferentia; tion to these, the vesicule and vasa defe- 7, That comprised between the two rentia have a muscular covering whose fibres Tine back sce eM gt aro arranged in s longitudinal ond tang: | fold of the vasa Joterettia': 10, YORRe direction, the latter being the most : Membranous or intrapelvic portion Superficial. This muscular lay’ er being con- of the urethral canal, covered by tinuous over the vesicule seminales and yas Wilson’s muscle; 11, 11, Cowper’s deferens, when it contracts, will co : glands enveloped by that muscle; onq shorten these ; consequently, it has 12, 12, Ischio-cavernosus muscle; 13, Accelerator urine muscle; ’ named the compressor vesicule et THE MALE GENITAL ORGANS. 861 seminalis. The fibrous coat of the vesicule is merely condensed cellular tissue.) The mucous and muscular coats are supplied with blood by the mg artery (inferior vesical) ; their nerves are derived from the pelvic plexus. The richness in glands of the mucous membrane of the vesicule seminales, has led several anatomists to consider them as organs of secretion, and not as reservoirs for the semen. But the large cavity that each forms, gan to demonstrate that they serve as reservoirs and secretory organs at same time. Their fluid production is added to the semen, as is the secretion of the prostate and Cowper’s glands. The ex duct is very short, and succeeds the narrow canal of the vesicula after the latter opens into the vas deferens. The two ducts pass between the prostate gland and urethra, and, after a brief course, terminate in the latter, on the side of the veru montanum—a tubercle which will be noticed presently. Near to, and in front of this tubercle, is a third very small orifice—tha. opening of the third pouch included between the serous duplicatures joining the vasa deferentia. (This is the sinus pocularis, or utriculus prostatia, vesicula seminalis tertia or media of Gurlt.) Improperly designated the third vesicula, or masculine uterus (Weber), this pouch (sometimes double) secretes a fluid which is thrown into the urethra. (This third vesicula is present in all the domesticated animals.) The ejaculatory ducts may become obliterated; then the secretion of the vesicule seminales accumulates in their interior, and gradually distends them until they attain enormous dimensions. We found, in a Gelding, a vesicula which was nearly as large as the bladder; it contained a brownish, sticky fluid, holding in suspension epithelial cells, free nuclei, and mucus corpuscles. (The vesicule seminales, in addition to their own secretion, receive the semen conveyed by the spermatic ducts, and keep it in reserve until copulation ; when the contraction of its muscular apparatus expels it into the ejaculatory ducts, and from these into the urethral canal.) 8. The Urethra. The urethra is a canal with membranous and erectile walls, commencing at the neck of the bladder, and terminating at the free extremity of the penis. Course—When followed from its origin to its termination, it is seen to at first horizontally backwards, then bend downwards at the ischial arch to leave the cavity of the pelvis, placing itself between the two roots of the corpus cavernosum, and passing forward in the channel formed at the lower border of these, until it arrives at the head (glans) of the penis, where it terminates by forming a small (cylindrical) prolongation, named the urethral tube. In its track, the urethra is divided into two very distinct portions: the intrapelvic, the shortest, and the eatrapelvic, the most ex- tensive, and supported by the corpora cavernosa. The latter division being alone enveloped by the erectile tissue that enters into the formation of the urethral walls, has been also named the spongy portion, the first being designated the membranous portion. nterior.—Internally, this canal has not the same width throughout. Very constricted at its origin, towards the neck of the bladder, it expands somewhat suddenly at the prostate gland; its dilatation, improperly named in Man the cul-de-sac of the bulb (bulbous portion), or, better, the ventriculus, 862 THE GENERATIVE APPARATUS. extends to its curve over the ischial arch, where it gradually contracts, After this it preserves the same reduced dimensions throughout its course, — though these dimensions may be increased during the passage of the urine __ or semen. There is, however, behind the urethral tube a small oval — dilatation, named the fossa navicularis (Fig. 403). Even throughout its extrapelvic portion, the inner surface of the urethra offers, near the neck of _ the bladder, and on its upper wall, the excretory orifices of the prostate gland, _ and which form two lateral lines of minute perforated tubercles. Between these two lines is found the urethral ridge or veru montanum (caput gal- — linaginus), a little eminence elongated from before to behind, on the sides of which the ejaculatory ducts open. Behind this are the exeretory orifices of Cowper’s glands. — Relations—The intrapelvic portion of the urethra is in relation, above, _ with the prostate, which adheres closely to it, and with the rectum, to which it is united by the abundant loose connective tissue in this part of the pelvis; below, it lies on the internal obturator muscle; laterally, it is related to the muscles and ligamentous or aponeurotic expansions that close in the sides of the pelvis. Without the pelvic cavity, the urethra is united in the most intimate manner to the corpora cavernosa, which embrace its anterior border. By its posterior border, it is related to the suspensory ligament of the penis. . Srrucrure.—The urethra is composed of: 1, Mucous membrane; 2, An erectile envelope; 3, Muscles; 4, Vessels and nerves; and, 5, we will add some remarks concerning the perineal aponeuroses, which are in immediate relations with this canal. 1. Mucovs Memsrane.—This is rather delicate, and forms the lining of _ the canal; it is continuous, posteriorly, with that of the bladder, and in front with the integument enveloping the head er of the penis ; it is also prolonged into the excretory ducts of the glands annexed to the urethra and the ejaculatory ducts. It has longitudinal folds, and is always in contact with itself, except during the passage of urine or semen; it has scarcely any papillw, only a few being found near the anterior extremity of the canal. The epithelium of this membrane is stratified and cylindrical, but at the portion furnished with papille it becomes pavemental. 2. Erecrite Envetore.—This envelope, lying outside the mucous mem- brane, does not cover the intrapelvic portion of the canal. It commences a little above the ischial contour, behind Cowper’s glands, by a very thick bulging portion, named the bulb of the urethra. In front, it terminates by another bulbous enlargement, into which the anterior extremities of the corpora cavernosa enter, named the head of the penis (glans penis). The tissue composing this envelope has the same organisation as other erectile apparatus, being a network of communicating cavities separated by elastic septa, the latter showing in their structure some contractile elements, 8. Muscies.—Behind the prostate gland, the mucous membrane of the urethra is covered by a fleshy layer of circular fibres, forming Wilson’s — muscle. Another muscular envelope, constituting the bulbo-cavernous or accelerator, also covers the erectile tissue of the urethra, accompanying it to near the glans, where it gradually disappears. To these two principal muscles of the urethra are added two apg of secondary fasciculi—the _ ischio-urethral and transversus perinet. his is the description of the muscular apparatus : a. Wilson’s muscle-—This may be described as a single muscle com- — posed of two portions, an inferior and superior. Both are formed by — -.” ey (a ~ a, a = _ ---- all mm : L ~ THE MALE GENITAL ORGANS. 863 transverse fibres thrown over the membranous portion of the urethra, and united at their extremities, which are attached by means of aponeurotic fasciculi, to the lateral walls of the pelvis. Behind, the superior fibres ver Cowper's glands, and, like the inferior, are mixed with the accelerator urine. b. Accelerator Urine.—Composed of transverse fibres encircling the urethra from the ischial arch to the free extremity of the penis, this will also be studied as a single organ, separated into two lateral portions by a median taphé passing along the whole posterior face of the urethra. The fibres pass from this raphé to the right and left, enter the furrow of the corpora cavernosa, and reach the upper surface of the urethra, where they advance towards each other; they do not join; so that the ‘circle formed by this muscle is necessarily incomplete. ¢. Ischio-urethral muscle (compressor urethre)—This is a thin fleshy band, pair, situated below and at the side of the membranons portion of the urethra. Attached by some aponeurotic fibres to the ischial arch, this muscle passes forward on Cowper’s gland, whose lower face it covers. At the periphery of that organ, it is confounded with the portion of Wilson’s muscle that envelops its upper surface. _ 4d. Transversus perinei—This is a very thin ribbon-like fasciculus, often searcely distinguishable from the ischio-anal muscle (levator ani). It extends transversely from the ischial tuberosity—to which it is attached through the medium of the sacro-sciatic ligament, to the mesial line of the perineum, where its fibres, confounded with those of its homologue on the opposite side, appear to be inserted in the accelerator urine at its origin. e. Action of the urethral muscles.—1. Wilson’s muscle, when it contracts, compresses between its two layers the membranous portion of the urethra. Tt is a veritable sphincter, and opposes the escape of the urine; when the semen is thrown from the vesicule seminales into the urethra, it also preyents that fiuid entering the bladder, by permitting the accelerator to empty, from before to behind, the initial dilatation of that canal. 2. The is correctly named from the part it plays in ejecting the semen from the urethra, it being the chief agent in this act. 3. The ischio-urethral muscle pulls back the membranous portion of the urethra, with Cowper's glands, and, like Wilson’s muscle, acts as a compressor to these. 4. The transversus perinei dilates the bulbous portion of the urethra, by drawing it out laterally. 4. Vessets anp Nerves.—The urethra is supplied with blood by the bulbo-urethral arteries and the two pairs of arteries—the dorsal of the penis. Voluminous veins, frequently varicose, and satellites of the arteries, carry it away. The lymphatics form a very rich plexus beneath the mucous membrane; their trunks pass to the inguinal, and some to the sublumbar glands. The nervous filaments are from the internal pudic and . great sympathetic. 5. Aponevroses or THE Pertvgum.—lIn the perineal region, the urethra is covered by two superposed fibrous layers. The superficial aponeurosis is fibro-elastic, and appears to arise from the inner surface of the thighs, where it is mixed with the dartos; it covers the perineum, and its fibres, ing disassociated, disappear on the sides of the sphincter ani. This membrane is in relation, externally, with the skin, and, internally, with the deep aponeurosis. On the middle of its external face, it receives the insertion of a muscular fasciculus, which is detached from the sphincter. The deep aponeurosis, formed of white inelastic fibrous tissue, adheres to bal wy “= 864 THE GENERATIVE APPARATUS. the latter by its outer face, and to the accelerator and ischio-cavernous muscles by its inner face. Above, it is lost around the termination of the rectum ; below, it expands between the thighs; it is seen insinuating itself, to the right and left, between the ischio-cavernous and semimembranosus muscles, to be attached to the ischiatic tuberosity. r., 4. The Glands annexed to the Urethra. A. Prostrate (Fig. 402, 8).—This single and symmetrical gland situated at the commencement of the urethra, and lies across the neck of the bladder. A constriction in the middle divides it into two voluminous — lateral lobes inclining slightly forward. Its upper face corresponds to the — rectum, through the medium of the cellular tissue at the bottom of the pelvic cavity. Its inferior face, moulded on the neck of the bladder, embraces it above and laterally, and is closely attached to it; it covers the terminal extremity of the deferent and ejaculatory ducts, and the neck of the vesicule seminales. a Srructvre.—The tissue composing this gland forms a number of communicating cells, which are larger in the Ass than the Horse; in these — is collected a quantity of viscid fluid (succus prostaticus) secreted by their walls, and which is ejected into the urethra by the two rows of orifices arranged on the sides of the veru montanum. These communicating cells are nothing more than conglomerate glands, which are distributed in a stroma of connective tissue and unstriped muscular fibres. B. Cowrrr’s Guianps.—In Veterinary anatomy, these are frequently named the small prostates. They are two globular bodies, denser in texture — than the prostate gland, but otherwise the same in organisation, and are situated on each side of the urethra, in the perineal region, above the ischial arch; they are completely enveloped by a somewhat thick fleshy cover- ing, formed by the fibres of Wilson’s and the ischio-urethral muscles (Fig. 402, 11). The fluid they secrete is thrown into the urethral canal by numerous _ orifices disposed in several rows. It has the same physical properties as that of the prostate, and both are poured into the urethra in abundance — immediately before ejaculation; the expulsion of the semen is by this means facilitated. ‘a 5. The Corpus Cavernoswm. The corpus cavernosum is an erectile stalk, which forms the base of the — penis and supports the urethra; it is situated between the thighs, prolonged beneath the abdomen, attached behind to the ischial arch, and terminates in front by a free extremity, which is received into the erectile enlargement named the glans penis. ‘ External conformation.—Flattened. on both sides, this body offers for study two lateral faces, two borders, and two extremities. The faces are plane, and present no interesting features. ‘The superior, or dorsal border, is the thickest, and is rounded. The inferior is channeled throughout its extent by a deep furrow which lodges the urethra. The posterior extremity — is bifurcated, the two branches constituting the roots (corpora or onal the — penis ; they are fixed to the ischial arch, one to the right, the other to the left, and are covered by the two ischio-cavernosus (erector penis) muscles: short, thick, and strong masses intersected by numerous tendinous fibres, and partly — concealed by the semimembranosus muscles. These erector penis muscles THE MALE GENITAL ORGANS. 865 arise from the ischial crest, and terminate on the membrane enveloping the erura of the penis, which they cover posteriorly and externally. The anterior extremity of the corpus cavernosum forms a blunt point, and is surrounded by the spongy tissue of the glans. Mode of attachment of the corpus cavernosum.—The chief attachment is constituted by the insertion of the two crura into the ischial arch. There is also a double suspensory ligament proceeding from the ischio-pubic sym- physis, where it is confounded with the superior attachments of the short uctor of the thigh, and passes to the dorsal border of the corpus cayernosum, a little in front of the point of union of its crura. Srrvoture.—This erectile organ is composed, externally, of a white, elastic, fibrous envelope, remarkable for its thickness, especially on the dorsum; it gives off, from its inner face, a certain number of lamellar trabecule which partition the interior of the cavity it forms. One of these septa (septum pectiniform) is directed vertically from the upper to the lower border, and divides the corpus cavernosum into two lateral portions (corpora cavernosa), which would indicate th: t the crura are not one mass at their point of union, but merely joined to cach other. In the Horse, this septum is generally very incomplete, and rarely extends the whole length of the organ. _ The lamellar prolongations sustain other elastic and contractile bands, which circumscribe the cavities in which is lodged the essential portion of the erectile tissue. According to Legros, the latter is composed of a network of capillaries interposed between the arterial and venous twigs, and which shows abrupt or regular dilatations of variable diameter. These successively dilated capillaries have very thin walls, which are adherent to the contractile prolongations of the envelope, and are lined by a very delicate pavement epithelium. In the areole of the cavernous tissue, cepa towards the base of the organ, the arteries offer a special isposition ; their walls are very thick, and they soon divide into a bouquet of branches which enter the areolw, where they terminate either by a cul-de- sac, or, which is most frequent, give off small free branc!:es convoluted in a iral manner. These are the arterie helicine described by Miller and Heatiet. (The walls of the cells are composed of white and yellow fibrous tissue, and unstriped muscular fibres. The cells themselves are in reality venous sinuses. Kélliker found a minute artery to proceed from each of the cecal terminations of the helicine arteries, and terminate, like the other capillaries, in the veins. The dilated vessels have been regarded by some anatomists as only vascular loops. The cells, during the erection of the penis, are distended with blood.) The arteries of the corpus cavernosum and dorsales penis pass into the erectile structure, and supply this organ with blood. The collateral veins of these arteries arise near the surface. The nerves come from the internal pudic and great sympathetic. 6. The Penis. The penis is the male organ of copulation, and results from the union of - the cavernosum and the spongy portion of the urethra. These parts - ius alseady been described; it now remains to consider the organ in its entirety. The penis commences at the ischial arch, passes between the thighs and the two dartoid sacs containing the testicles, and is prolonged beneath the belly, where it terminates in a free extremity. : K 866 THE GENERATIVE APPARATUS. All the portion comprised between the ischial arch and the scrotum, is maintained and deeply covered by the surrounding textures, and isnamed = the fixed portion of the penis. The remainder of the organ—its anterior — moiety—is, on the contrary, its free portion, as it forms a detached appendage _ sustained by a cutaneous fold, the sheath (or prepuce), ; Ds The Frxep Portion occupies the perineal region and that between the thighs, where it is enveloped by the arteries, veins, and nerves already known, as well as by a large quantity of connective tissue (and the skin), The FreePortion is lodged in the sheath during the inactive condition _ of the organ, but protrudes from it when in a state of erection. It is then seen to be covered by a smooth, unctuous tegumentary membrane with numerous papille, and of variable colour, though most frequently it is black or variegated. Its base presents a slight circular enlargement, due to the ac- cumulation, beneath the mucous membrane, of a small annular mass of elastic and contractile tissue. Its ea tremity or glans is also a cir- — cular enlargement limited behind by a salient collar— the corona glandis—which is notched inferiorly, and at the moment of ejaculation assumes a considerable de- velopment, its shape being then not unlike the rose of LONGITUDINAL SECTION OF THE FREE EXTREMITY OF & watering-can. This en- THE HORSE’S PENIS; IN A RELAXED STATE. largement has for its basis 1, Erectile tissue of the corpus cavernosum; 2, Urethra; the terminal expansion of 3, Fossa navicularis; 4, Urethral tube; 5, Erectile the urethral erectile tissue, tissue of the urethra; 6, Ditto of the glans; 7, ong presents on its anterior Corona glandis ; 8, Urethral sinus. face: 1, ag contre, a rounded prominence due to the point of the corpus cayernosum; 2, Beneath this, the urethral tube encircled by a fossa; 3, At the bottom of the fossa, and below the urethra, the orifice of a bilocular cayvity—the urethral sinus, which widens at the bottom, and in which accumulates sebaceous matter that sometimes becomes so hard as to prevent the flow of the urine by compressing the tube; 4, Inferiorly, the suburethral notch. The skin covering the extremity of the penis is rich in nerves which, according to Kraiise, have round dilatations which he designates as “terminal genital corpuscles.” To complete the description of the penis, there only remain to be described: 1, Two suspensory and retractile cords which concur, with the natural elasticity of the fibrous envelope of the corpus cayernosum, to return the organ to its ordinary position when the phenomenon of erection has ceased ; 2, The tegumentary fold, or sheath, which envelops the free portion of the penis when in its ordinary state of repose. A. Suspensory AnD Rerractite Corps or THE Penis.—T'wo in number, these cords arise from the lower face of the sacrum, descend as flat bands in front of the sphincter ani, between the retractor muscle of the anus and the rectum, to which they give numerous short fasciculi from their posterior Fig. 403. THE MALE GENITAL ORGANS. 867 border; they then unite at the mesial line, below the anal opening, thus forming around the terminal extremity of the rectum a real suspensory ring. uyi ther, and intimately united, they are continued on the accelerator, which they follow at the raphé, and are eventually lost in its texture near the free extremity of the penis. ; These cords are composed of unstriped muscular fibres. B. Suearu (prepuce).—The sheath is a cavity formed by a fold of the abdominal integument, and lodges the free portion of the penis; it is entirely effaced at the moment of erection, when the copulatory organ is lengthened and enlarged. The skin at the opening of the sheath enters its cavity, and, on arriving at the free portion of the penis, forms a circular cul-de-sac in becoming reflected over the organ, which it envelops. This lining integument of the sheath is fine, and very irregularly plicated ; it is destitute of hair, and holds a middle place, with regard to isation, between the skin and mucous membranes. It contains in, or beneath, its substance a considerable number of sebaceous or preputial glands that secrete an unctuous fatty matter (exhaling a pecular odour, and dark- y in colour, the smegma preeputii), which is spread over the surface of membrane. Above, the inner integument of the sheath is applied to the fibrous tunic of the abdomen. Below, and on each side, the cutaneous fold constituting this cavity contains between its layers an expansion of yellow elastic fibrous- tissue, the lateral portions of which, attached to the abdominal tunic, are named the suspensory ligaments of the sheath. Tn the Ass, there exists, near the entrance to the sheath, and on each side, a small tubercle which may be looked upon as a rudimentary teat of the female. . (The prepuce protects the penis, and sustains it when in a flaccid state. Tn certain Horses, a gurgling sound is produced in trotting, from the air entering and leaving the sheath suddenly.) DIFFERENTIAL CHARACTERS IN THE MALE GENITAL ORGANS OF OTHER THAN SOLIPED ANIMALS. Rouminants.—Testicles—In these animals, the testicles are very voluminous, oval, and vertically elongated. They, with their envelopes, form a pendant mass that occupies the inguinal region. The scrotum is always of a pale colour. In the interior of the testicle, the corpus Highmorianum and the rete testis are very marked. (The proper tissue is yellow, and the septa formed by the prolongations of the tunica albuginea are not very distinctly -een.) Epididymis.— Vas deferens. —The head of the epididymis is wide and flat, and partly covers the anterior border of the testicle. The middle portion, smaller than in Solipeds, re ts a narrow cord lying outside the posterior border of the seminal gland. The is a little free appendage, inflected inwards and upwards to become continuous with the vas deferens. The latter is dilated, as in the Horse, when it arrives above the bladder, and lies beside the duct of the opposite side. The two, thus joined, increase from before to behind, leave the neck of the bladder in ing above the vesicule seminales, then rape the prostate, and terminate in the urethra, on the summit of a ridge, by two Vevioule seminales.—In the Bull, the vesicule seminales have not the same appearance as in the Horse, and they have not so large a cavity in their interior. They are two elongated masses, lobulated on their surface, yellow in colour, and poseeesing quite a glandular aspect. They have sometimes been designated the lateral prostates. They are com of aciniform glands, inclosed in a mass of connective tissue and unstriped fibres ; n into a common central canal which terminates in the vas deferens. Urethra,— canal is inflected like the letter 8, Its diameter larly diminishes from its commencement to its termination, which is not provided with a urethral tube, as in Solipeds. Internally it presents: 1, Immediately beyond the re “ bladder K 868 THE GENERATIVE APPARATUS. a short, but very salient veru montanum, which divides into two mucous cen, Sea gadnelly subside posteriorly ; 2, Towards the ischial arch, a valve whose free 4 = irected downwards, covers a cul-de-sac about 3-4ths to 1 inch — Te The structure of the urethra is also different. The walls of the membranous pores a, are thicker than in the Horse; they have a layer of erectile tissue, and a Wilson’s muscle, very thick below and laterally, and whose fibres are inseited in the middle of the upper surface, into an aponeurotic raphé. ae At the ischial arch, when the canal bends downwards, the spongy tissue becomes 4 ; more abundant to form the bulb of the a Fig. 404. urethra ; but the prominence at this point = 7 A is chiefly due to the accelerator urinm, = as is shown in figure 404, o, 4. This 4 muscle is extremely powerful, but it soon ceases beneath the ischial arch. The transversus perinei is as strong as in Solipeds. Glands annexed to the urethra.— Cowper’s glands are absent. The pros- tate gland is not voluminous, and forins, at the commencement of the urethra, ; a little transverse yellow mass, beneath B which pass the vasa deferentia; it also lies beneath Wilson’s muscle, and is rolonged for some distance on the mem- fennins portion of the urethra, ; { Penis.—In the Bull, the penis is long and thin, and carried well forward be- neath the belly. It is inclosed at the perineum in an aponeurotic sheath, which is covered by the ischio-tibial muscles, This sheath is double, its superficial layer being continuous with the dartos, and has same physical Cc characters; the deep layer is thin, white, and inelastic. In front of the pubis, the pen's des- cribes two successive curves—the S$ the penis—the first with its convexit, ——— = second hegre It is at the second curve that the suspensory ligaments join the penis, and continue along its sides to its ee The free portion of the organ, ver tapering, is covered by a fine, apil. lated, very sensitive, rase-coleaall mucous membrane. It is lodged in a narrow sheath that advances much more forward beneath the abdomen than in Solipeds, and has at its opening a bunch of long stiff hairs. This cutaneous sheath is moved by four SECTIONS OF THE URETHRA OF THE OX AT subcutaneous muscles: two ror pcorplahagycny apr “ctr retractors (Fig. 405, 2) which drat the A, Intrapelvic portion; 1, Wilson’s muscle; 2, sheath backwards, and concur in ex Erectile tissue; 3, Urethral canal; 4, Prostate : : gland.—n, The middle ofthe pens; 1, Fibrous rections utd two anterior oF protractor cord of the corpus cavernosum; 2, Urethral jyecles (Fig. 405, 1) which carry the canal; 3, Its erectile tissue; 4, Envelope of jhoath forward to its former position, the corpus cavernosum.—¢, At the crura of the ‘he jatter are found in the Cow, and do penis; 1,1, Crura of the corpus cavernosum; jo¢ 4 pear to be of any use, : ; 2, Urethral canal; 3, Its erectile tissue; The two constituent portions of the 4, Accelerator urine; 5, Ischio-cavernosus copulatory organ are not joined in the muscle. same manner as in Solipeds, tlie channel for the lodgment of the urethra being transformed into a complete canal by a narrow layer of the fibrous envelope of the corpus ~E THE MALE GENITAL ORGANS, 869 cavernosum. The latter is little developed, and presents, internally, a longitudinal fibrous cord; it is not much dilated during erection, In this act. the penis is elongated by the straightening out of its curvatures, rather than by any real lengthening; when erection ceases, the organ is retracted into the preputial cavity by the contraction of the sus- pensory cords, which reform its double inflection behind the scrotum. In the Ram and He-goat, the disposition of these parts is somewhat similar. (In the former, the extremity of the urethra has the form of a narrow cylinder curved backwards, its opening being a longitudinal slit. In Ruminants, towards the extremity of the sheath are small teats; these, in the He-goat, are sometimes glandular, and secrete a fluid analogous to milk.) Fig. 405. ) Ve ro mN PENIS AND MUSCLES OF THE SHEATH OF THE BULL. 1, Protractor muscle of the sheath ; 2, Retractor of ditto; 3, Testicles in the scrotum ; 4, The S of the penis; 5, Suspensory cords of the penis attached to the second curve; 6, Subcutaneous abdominal vein. Pic.—The testicles of this animal are round, and placed in the perineal region. The serotum is narrow, and but little detached: the pouches of which it is composed appearing simply as two hemispherical prominences on the surface of the perineum. here is nothing particular to be remarked in the epididymis and vas deferens; (the tail of the first is very voluminous; the latter has no pelvic dilatation.) The vesiculz seminales, with regard to disposition, are intermediate between those of the Horse and Ox Their walls are thick and very glandular, and their interior is diverticulated. (They are, proportionately, very large, and, in structure, closely re- semble those of Ruminants; indeed, in these animals they rather appear to be organs for the secretion of a milky liquid that is mixed with the semen, than reservoirs for the fecundating matter, as that fluid never contains any spermatozoa.) There are two prostates: one disposed as in the Ox; the other placed across the neck of the bladder, as in Solipeds. The penis resembles that of Rumivants, except in the absence of the muscles of the sheath; it has also a particular preputial sheath, which has been studied 870 THE GENERATIVE APPARATUS. by Lacauchie. (When flaccid, the penis of the Pig is twisted in a spiral manner at extremity. The sheath is narrow, and longer than in Ruminants. At the up its opening is the special poucli mentioned by Chauvean, and which is fo by a fold of the skin It opens into the sheath, and secretes, in the Boar, an unctuous fluid, possessing a particularly disagreeable smell, and which is mixed with the urine. The odour of the secretion even taints the flesh of this creature.) Carntvora.—The testicles of the Cat are formed like, and placed in the same situation as, those of the Pig; those of the Dog are more oval, and are pendent. The Carnivora have no vesicul# seminales. The prostate gland surrounds the neck of the bladder ; it is of a yellow colour, concave on its upper surface, and divided into, two lateral lobes on its lower face. Cowper’s glands are absent in the Dog; they exist in the Cat (in which they are very small, and excrete their secretion by separate efferent canals). The wrethra (in its pelvic portion) is very long; towards the ischial arch it shows an enlargement or bulb, though this is less, proportionately, than in the Ox; the accelerator muscle is continued for a longer distance around it. (The spongy portion is thinner in the Cat than the Dog.) “In the Doy, the penis is long and pointed. The posterior half is constituted by the corpus cavernosum, which is little developed, and has not a complete middle septum. The anterior moiety has for its base a bone, found in several other mammifers, which is intended to favour the introduction of the penis into the genital organs of the female. “ The penien, or penial, bone is elongated, conical, and incurvated, so as to constitute a furrow inferiorly, in whicl is lodged the urethra when it leaves the fibrous channel of ’ the corpus cavernosum; its apex, anteriorly, partly forms the point of the penis; its base is intimately united to the anterior portion of the corpus cavernosum; the septum, which is very dense, is fixed in this bone, as is the fibrous envelope which mixes with its periosteum. “The penial bone almost entirely constitutes the base of all that portion of the included within the sheath ; in addition, this part possesses two distinct erectile ments—an anterior and posterior. The first is analogous to that of the glans penis of Horse, and is formed by an expansion of the erectile tissue of the er at its anterior base, it has there a point suddenly bent downwards, beneath which is pierced the urethral orifice ; posteriorly it is thin, and partially covers the other erectile mass. The latter is supplementary; it begins at the base of the free portion of the nis, where the integument of the sheath is folded in a cireular manner around it. rom 1 to 1} inches long, it embraces the upper border and sides of the bone; pyramidal in shape, its base, which is posterior, is $ to 1} inches thick; in front, it thins away beneath the erectile tissue of the head. ; “ Such are the two erectile masses, whose summits overlap, so that the free portion of penis, bulging in front, and still more so behind, is narrowest in the middle. Although contiguous, these two vascular dilatations are independent of each other; the posterior has, likewise, no communication with the corpus cavernosum, oe two parti- cular veins which pass backward in a lateral groove. Each is erected separately during copulation, when they assume a large size; the great volume of the posterior enlarge- ment prolongs the duration of this act, until flaccidity ensues. This peculiarity is a consequence of the absence of the seminal reservoirs (the vesicule seminales). “In the Dog, two small muscles are found which appear to be destined to elevate the penis and direct it during its introduction into the sexual parts of the female, as its erection is always feeble. These are two fasciculi which proceed from the crura of the penis, and pass forwara to unite in a common tendon implanted on the dorsal border of the organ; they thus resemble the chord of an are. “'The subpenial muscular cords exist as in the other animals. The sheath is narrow and long, and, as in the didactyles, has protractor muscles; the integument is thin and rose-coloured, like that covering the free portion of the penis. “In the Cat, the penis is short, and directed backwards; but in a state of erection it is inclined forwards for copulation. Its free portion presents some peculiarities. It is conical, and its summit, near which is pri the urethral opening, has for its basis a small incomplete penial bone, that encloses a layer of erectile tissae—an expansion of that of the urethra. This free portion is pact by an integument studded with some- what rigid papille directed backwards, and capable of being made erect during copulation. These points, which are met with in nearly all the Cat kind, are analogous to the hairs, scales, strong spines, and even the cartilaginous saws, of certain other animals, and which appear to be related to the degree of sensitiveness of the female sexual organs.”—A, Lavocat. 7 ; club-shaped THE MALE GENITAL ORGANS. 871 * COMPARISON OF THE GENITAL ORGANS OF MAN WITH THOSE OF ANIMALS, Coverings of the testicles—The scrotum, dartos, tunica erythryoidea, and tunica is have the same organisation as in Solipeds. The scrotum is rich in sebaceous g and the tunica vagivulis is separated by a serous layer from the peritoneal cavity. esticles.—These are ovoid, and situated in an oblique direction downwards and inwards; their largest curvature is forwards, The epididym’s offers the same arrangement as already noticed, except that the vas deferens, in being detached from the globus minor, is bent somewhat suddenly to reach the abdominal cavity. There are several diverticuli annexed to the epididymis, named the pediculated hydatid of Morgagni, non-pediculated hydatid aberrant vessels, and corpus innominatum of Giraldes. Fig. 406. SECTION OF PELVIS TO THE LEFT OF THE MEDIAN LINE AT THE PUBES, AND THROUGH THE MIDDLE OF THE SACRUM, 1, Section of left pubic bone; 2, Peritoneum on bladder; 3, Left crus penis; 4, Pelvic fascia forming anterior ligaments of bladder; 5, Part of accelerator urine ; 6, Posterior layer of triangular ligament forming the capsule of the prostate; 7, Anterior layer of triangular ligament; Between 6 and 7 are seen the membranous urethra, deep muscles of urethra (insertion), and Cowper’s gland of the left side; 8, Vas deferens; 9, Bulb of urethra; 10, Rectum; 11, Cut edges of accelerator uring and transversus perinwi; 12, Left ureter; 13, Reflec- tion of deep layer of superficial fascia round transversus perinwi; 14, Left vesicula seminalis; 15, Cut edge of levator ani; 16, Rectum; 17, Prostate gland. The hydatid of Morgagni is a little projection at the head of the epididymis, fil with a Shs aud which is never ote with the semen. The an-pieoued Rdasid is a small white mass which rises from the testicle at some distance from the globus major ; it has a cavity that communicates with the duct of the epididymis. The aberrant vessels are fine flexuous ducts given off from the globus minor, and soon terminate in a cul-de- gac. Tlie corpus innominatum of Giraldés is a small mass of ramifying tubes included in the connective tissue uniting the globus major to the testicle. All these appendages of the testicle or epididymis, are the remains of the Wolffian body. Vas deferens.—This is not united to its fellow by a peritoneal fold; it is slightly dilated on arriving at the neck of the bladder, as in the Horse. The vesicule seminales are elongated, and lobulated on their surfrce, as in Ruminants. Urethra.—This canal has a fixed and a free portion: the first is slightly inclined downwards and forwards; the second is suddenly inflected, and, with the preceding, forms the prepubic angle, which disappears with erection. Its diameter increnses a little at the bulb, and again at the meatus, to form the fossa navicularis. Its erectile envelope forms a considerable enlargement at its commencement—the bulb, and this is covered, as in the Ox, by the accelerator urine; it also composes another, the glans, that 872 THE GENERATIVE APPARATUS. constitutes the head of the penis. On its inner surface are some valvular folds, some —__ depressions, the lacunx of Morgagni, the veru montanum, and towards the summit of this a small pouch—the male uterus (sinus pocularis), which, on a very reduced scale, repre- sents the third vesicula of Solipeds. ‘The muscles of the urethra are the ischio-cavernosum, accelerator urine, Wilson's muscle, and the tranaversus perinwi—superficial and deep. oF ey emerging from the pelvic cavity, the urethra traverses an aponeurotic membrane the ligament of Carcassonne. Corpus cavernosum.—T Lis offers nothing particular in its disposition. ; tie Penis.—This organ is free, and is suspended in front of the pubis. It is en = by a fibrous covering —the superficial fascia, and a cutaneous cylinder—the sheath, Itis attached by two supensory ligaments: the superficial is elastic, and arises from the linea alba; the deep is inelastic, and is detached from the symphysis pubis and the anterior _ pillar of the inguinal ring. (It is usual to describe only one ligament—the UWgamentum suspensorium penis, separating to form two layers which give passage to the dorsal vessels, and nerves of the penis.) The glans is separated from the rest of the a constriction designated the cervix, and around this the skin forms a (cireular) fold—the __ prepuce, which covers the glans more or less completely. It is attached to the middle of ~~ its lower face by a thin fold—the frenum preputii, The inner surface of the prepuce _ has a large number of scbaceous glands, CHAPTER II. : GENITAL ORGANS OF THE FEMALE, TuHEsE organs resemble those of the male in their general disposition. Thus we find in the female: 1, Two secretory organs, the ovaries, analogous to the testicles, and charged with the elaboration of the germ; 2, The uterine (Fallopian) tube, disposed, like the epididymis and vas deferens, as a flexuous canal, through which the ovum passes on leaving the ovary ; 3, The uterus, a single reservoir formed of two lateral moieties which may be compared to- the vesicule seminales, as it is there that the germ remains until it is fully developed ; 4, The vagina, a membranous canal analogous to the urethra, and giving passage to the foetus after it has been formed in the uterus: this canal, which receives the penis during copulation, also shows, at its exterior opening, the vulva, an erectile apparatus, and the clitoris, which is nothing more than a rudimentary corpus cavernosum of the male. The female has — also certain glands, which, in many species, exist in a rudimentary form in the male: for instance, the mamma, organs for the secretion of milk, the first nourisiment of the young animal. (The glands of Duverney, in the female vagina, seem to be analogous to Cowper’s glands in the male, as they are present in the females of all animals where the latter exist in the male, and their secretion appears to be of the same character.) It may be remarked, after this enunciation, that the male and female genital apparatus are constructed on the same type: a circumstance which is most clearly demonstrated at an early period of intra-uterine life, when it is impossible to distinguish the sexes. 1. The Ovaries. (Fig, 411, 1.) Situation—Form—Relations.—The ovaries (testes muliebres), the essential organs of generation in the female, are two ovoid bodies, smaller than the testicles, though of the same shape, situated in the abdominal cavity,’ and ' The ovaries sometimes leave this situation. Thus M. Dupont, of Plazac, has observed them, in four swine, occupying little cavities, analogous to those of the male scrotum, in the perineal region,—‘ Journal des Vétérinaires du Midi,’ December, 1869, THE FEMALE GENITAL ORGANS. 873 ‘suspended from the sublumbar region, where they correspond with the intestinal convolutions, a little behind the kidneys. Smooth on the surface, these organs present, in the middle of their upper face, a deep, and more or less oblique fissure, resembling the hilus of the kidney; this gives attach- ment to the pavilion of the tube. Means of aitachment.—The ovary floats at the anterior border of the broad ligament ; it is also sustained by the vessels which enter it, and by a small cord of unstriped muscular fibres, the ligament of the ovary, which attaches it to the uterus. Srrvorure.—The organisation of the ovaries comprises a serous mem- yl a tunica albuginea, proper tissue, and the Graafian vesicles imbedded erein. Serous membrane.—This is a continuation of the broad ligaments; it covers the whole organ (except at the hilus), adhering closely to the tunica albuginea. Tunica albuginea,—This is similar to that enveloping the testicle, being a very resisting fibrous case which sends prolongations into the substance of the ovary. Proper tissue.—The proper tissue, or stroma, of the ovary is more con- sistent than that of the testicle ; it is hard, grates on being cut into, and is greyish-yed in colour. It is divisible into two layers, distinguishable by their aspect and structure. , , 1. The medullary layer, that nearest the hilus, is slightly red and spongy; it is formed by an interlacing of the connective fibres, unstriped muscular fibres, and a large number of vessels that radiate from the centre towards the periphery. 2. The cortical layer has the elements of connective tissue for its base ; it is but little vascular, and contains in its substance the Graafian vesicles or follicles (ovisacs), and is consequently often named the ovigenous layer. These ovisacs are in various stages of development; the smallest are situated beneath the tunica albuginea, and gradually increase as they lie deeper. When fully developed, they are filled with a transparent, citron- coloured fluid ; the ovigenous layer can then no longer contain them, and they protrude more or less from the surface of the ovary. A Graafian vesicle, in its perfect state, is composed of an envelope and its contents. The envelope comprises: a fibrous membrane (tunica fibrosa), which is confounded with the stroma of the ovary, and in it we may re- cognise two layers, the internal of which is rich in vessels; and an epithelium, or membrana granulosa, consisting of round or polygonal granular cells. At the bottom of the ovisac, this epithelium forms a small mass—the cumulus proligerus (or germinal eminence), in the centre of which is the ovulum or egg of the mammal. The contents (liquor folliculi) are a clear yellow fluid, which becomes red on admixture with blood when the vesicle ruptures. The orulum or ovum is a cell about 1-100th of an inch in diameter, inclosed in the discus proligerus or cumulus proligerus. The ovulum is invested by an amorphous, thick cell-membrane —the zona pellucida (mem- brana vitellina); its granular contents are named the vitellus or yelk ; and its (vesicular nucleated) nucleus, designated the germinal vesicle, aud lying at a certain point on the zona pellucida, has in its centre a white patch—the germinal spot. Vessels and nerves.—The thick, flexuous, arterial divisions are given off by the utero ovarian artery; they ramify in the spaces formed by the tunica albuginea, before reaching the proper tissue by entering the hilus. The 874 THE GENERATIVE APPARATUS. veins are of large calibre, and form a very rich network around the gland —the bulb of the ovary ; they terminate in the vena cava, near the renal veins. __ The lymphatics pass to the sublumbar glands. The nerves emanate from the small mesenteric plexus. ; Drvetorment.—The ovary of Solipeds is of great size in the foetus, being often nearly as large as in the adult animal. It becomes wastedin aged animals. ' : ! Funorions.—The productive organs of the germ or ovum, the ovaries are the testicles of the female. They form the ovulum, and then at a cer- tain period set it at liberty. As the ovule are contained in the ovisacs, it is necessary to study: 1, The development of these ovisacs; 2, Their rupture or dehisence; 3, The phenomena occuring in them after this rupture. ie ¥ Plwalijanl of the Ovisacs.—The ovisacs already exist in the ovary of the foetus and the young animal, but only assume their greatest activity at the age of puberty. They are not all formed at birth, but are incessantly re-developed, this development taking place beneath the tunica albuginea, (At puberty, the stroma of the ovary is crowded with ovisacs so minute, that in the Cow it has been computed that a cubic inch would contain ‘ hundred millions of them.) . : ; At first the ovisac consists of a small.cell, which sre presents all the constituent parts of the ovulum. As it becomes developed it sinks into the cortical layer, being pushed deeper into it by the cells that grow outside it; and it is also surrounded by a granular membrane, formed at the expense of the nuclear elements of the adjacent connective ‘tissue. © This membrane soon separates af a given point into two layers, to form a cavity that gradually extends and becomes filled with fluid: this is the cavity of the ovulum. As the separation is not complete, the ovulum, enveloped by the internal granular membrane, remains beside the external granular membrane, and while the cavity is increasing, the tissue of the ovary, pressed around it, is condensed, constituting the — fibrous wall of the ovisac, which afterwards receives a network of vessels. Rupture of the Ovisacs.—Until puberty, the ovisacs do not exhibit any very marked phenomena; at this period, however, the ovary becomes vascularised, and a certain number of Graafian vesicles increase in OVARIUM OF THE RABBIT yolume. At the period of cestrum, one or more of AT THE PERIOD OF these, according to the species, participate in the va ntots Stace op Change in the ovary, become vascular and distended, THE EXTRUSION OF and finish by rupturing and evacuating the discus ova. proligerus and ovulum. The latter is received into the Fallopian tube and conveyed towards the uterus. Corpus Luteum.—After the rupture of a Graafian vesicle, its cavity is filled by a clot of blood which gradually contracts and loses its colour; at the same time the fibrous membrane becomes hypertrophied, and the granular layer is wrinkled and transformed into cylindrical epithelium. To this period of progression succeeds one of regression; during which the cylindrical cells become infiltrated with fat and are gradually absorbed. THE FEMALE GENITAL ORGANS. 875 The term corpus luteum is given to the cicatrix resulting from the rupture of the ovisac. The of the phenomena of hypertrophy and regression is much slower when the escape of the ovulum has been followed by impregnation ; Fig. 408. Fig. 409, CONSTITUENT PARTS OF MAMMALIAN OVUM. Fig. 408, Entire ovum; Fig. 409, Ovum ruptured, with the contents escaping ; mv, Vitelline membrane; j, Yolk; vg, Germina! vesicle ; tg, Germinal spot. so that we have false ropes lutea (those which are independent of preg- nancy), and frue corpora lutea, those of gestation, and which do not disappear until several weeks after parturition. (The true corpora lutea are recog- 7 Fig. 410. (0608 OOOO SUCCESSIVE STAGES IN THE FORMATION OF THE CORPUS LUTEUM IN THE GRAAFIAN FOLLICLE OF A SOW; VERTICAL SECTION. a, The follicle immediately after the expulsion of the ovum, its cavity being filled with blood, and no ostensible increase of its epithelial lining having yet taken place; at 6, a thickening of this lining has become apparent; at c, it begins to present folds which are deepened at d, and the clot of blood is being absorbed and decolorized ; a continuance of the same process, as shown at ¢, f, y, A, forms the corpus luteum, with its stellate cicatrix. nisable, after parturition, as small white or dark-coloured masses, the corpora albicans vel nigrum. The yellow colour to which they owe their pame is due to the infiltration of the cylindrical cells with fat.) Such are, very briefly, the functions of the ovary. 876 THE GENERATIVE APPARATUS, (Beneath the hilus of the ovary, and between the layers of the broad ligament and the round ligament, is found asmall body, usually described as the parovarium, consisting of a number of fine tubes with blind extremities, __ It is considered as the remains of the Wolffian body: a foetal structure that forms the epididymis in the male, and has been named the organ of Rosen- muller in the female. Chauveau does not mention its existence in the domesticated animals, though Leyh does.) a 2. The Oviducts, or Fallopian or Uterine Tubes. (Fig. 411, 2.) The uterine tube is a little flexuous canal, lodged in the broad ligament, near its anterior border. It commences at the ovary by a free, expanding oxtremity—the pavilion of the tube (or ostium abdominale), and terminates — in the cul-de-sac of the uterine horn by opening into it (the ostium uterinum), Its canal at the middle is so narrow as scarcely to admit more than a very thin straw, and its calibre is still less towards the uterine extremity; near — the ovary, however, it is wide enough for the passage of a thick goose-quill. The orifice of the uterine extremity opens in a small and very hard tubercle. The ovarian extremity, in oll mammalia, offers a very remarkable arrangement. It opens into the peritoneal cavity, near the fissure of the ovary, and in the centre of the expansion named the pavilion of the tube, — which is also designated the fimbriated extremity (or morsus diaboli), This pavilion is attached to the external side of the ovary, and has a very _ irregular outline: notched as it is into several lancet-shaped, unequal pro- longations (fimbriew), which float freely in the abdomen. Here are, then, two important anatomical facts: the discontinuity between a gland and its excretory canal, and the communication of a serous cavity with the exterior. a SrxvcturE.—The oviduct is formed of a serous, a contractile, and a mucous tunic. The serous (external) is furnished by the broad ligament, end is derived from the peritoneum. The contractile (middle) is constituted by unstriped muscular fibres, which extend into the pavilion. (They are arranged as circular—internal, and longitudinal—external fibres, and are con- tinuous with those of the uterus; they are mixed with immature nucleated areolar tissue.) The mucous membrane is in longitudinal folds in the tube, but in the pavilion these folds are radiating; it is covered by a ciliated — cylindrical epithelium (the vibrations of the cilia being towards the uterus.) (It has very few glands and no villi.) At the margin, or fimbrie, of the pavilion it suddenly ceases, and is continued by the peritoneum (a serous syst is frequently found in this situation; at the other extremity the mucous membrane is continuous with that of the uterus). Fonorions.—The excretory duct of the ovary, the uterine tube, seizes the ovulum expelled from the ovisac, and carries it to the uterus. It is therefore necessary that, at the moment of rupture of the ovisac, the fimbriz- should be applied to the ovary, in order to receive the germ and bring it to the abdominal orifice of the tube. The application of the pavilion to the ovary is brought about either by the contraction of the muscular fibres it contains, or through the distention of the bulb of the ovary. Some- times this mechanism is insufficient, and the ovulum falls into the abdominal - cavity, becomes fixed there, and is developed if it has been previously fecun- dated; this occurrence constitutes the most remarkable variety of extra- uterine gestation. The oviduct also conveys the seminal fluid of the male to the ovulum. THE FEMALE GENITAL ORGANS. 877 3. The Uterus. (Figs. 411, 412.) The uterus is a membranous sac to which the ovulum is carried, and in which it is developed. Situation.—It is situated in the abdominal cavity, in the sublumbar region, at the entrance to the pelvic cavity, where its posterior extremity is ¢ Form and relations—In its posterior moiety, the uterus is a single cylindrical reservoir, slightly depressed above and below; this is the body of the uterus. Its anterior moiety is bifid, and gives rise to two cornua, which curve upwards. The body is related, by its upper face, to the rectum, which lies on it after passing between the two cornua; it receives, on the sides of this face, the attachment of the broad ligaments; its lateral and anterior faces are related to the intestinal convolutions. (Inferiorly, it is in relation with the bladder.) Its anterior extremity (or fundus) is continuous, without interruption, with each of the cornua; the posterior is separated from the vagina by a constriction of the neck (cervix) of the uterus. The cornua, mingled with the different portions of intestine which occupy the same region, offer: a free and convex inferior curvature; a superior curvature, to which the suspensory ligaments are attached; a posterior extremity, or base, fixed to the body of the organ; and an anterior extremily or summit—a rounded blind pouch looking downwards, and showing the entrance of the oviduct. Means of atiachment.—Floating in the abdominal cavity, like the in- testines, the uterus is also, like them, attached by lamellar bands which suspend it to the sublumbar region, and which for this reason have been named the suspensory or broad ligaments of the uterus. These bands are two in number, are irregularly triangular in shape, and are more developed before than behind. Close to each other posteriorly, and separating in front like the branches of the letter V, they leave the ~ sublumbar surface and descend towards the uterus, to be attached by their inferior border to the sides of the upper face of the body and the small curvature of the cornua. Their anterior body is free; they sustain the oviducts and ovaries, the former being placed between the two serous layers of the ligament, and the latter, placed within this ligament, receives a band detached from the principal layer, forming with it, beneath the ovary, a kind of small cupela. There is also another little narrow long band outside the broad ligament, and which can be traced as far as the upper inguinal ring. Anteriorly, it has a small enlarged appendix ; between the two layers forming this fold is found a thin muscle, altogether like the male cremaster before the descent of the testicle into the scrotum. This may be looked upon as the analogue of the round ligament of Woman. E The uterus is also fixed in its situation by its continuity with the Interior.—The inner surface of this organ offers mucous folds, which exist even in the foetus; they are arranged in a longitudinal series, and are not effacable by distension; thongh they disappear during gestation, con- sequent on the enlargement that takes place in the uterine cavity. This cavity has three compartments: the cavity of the body, and those of the cornua. The latter are pierced, at their extremity, by the uterine orifice of the Fallopian tube; while the former communicates with the 878 THE GENERATIVE APPARATUS. Fig. 411. V VERMORCKEM sa GENERATIVE ORGANS OF THE MARE, ISOLATED AND PARTLY OPENED. 1, 1, Ovaries; 2, 2, Fallopian tubes; 3, Pavilion of the tube, external face; 4, Ibid., inner face, showing the opening in the middle; 5, Ligament of the ovary; 6, Intact horn of the uterus; 7, A horn thrown open; 8, Body of the uterus, upper face; 9, Broad ligament; 10, Cervix, with its mucous folds; 11, Cul-de-sac of the vagina; 12, Interior of the vagina, with its folds of mucous membrane; 13, Urinary meatus, and its valve, 14; 15, Mucous fold, a vestige of the hymen; 16, Interior of the vulva; 17, Clitoris; 18, 18, Labia of the vulva; 19, Inferior commissure of the vulva. THE FEMALE GENITAL ORGANS. 879 vagina by @ narrow canal that passes through the posterior constriction of the uterus (cervix), and which is, in Human anatomy, named the cavity (or canal) of the cervix (08 uteri, 08 externum, os trice). In all the domesticated animals, except the Rabbit, the uterine canal is prolonged to the bottom of the vagina, in something the same fashion as a tap is into the interior of a barrel ; and in this way it always forms a very marked projection in the vaginal eayity. Around this projection, the utero-vaginal mucous membrane is ised in transverse folds disposed in a circular manner, which give it the appearance of a radiated flower; in Veterinary anatomy, this projection of the cervix is consequently named the “ expanded flower ”—fleur épanouie ; it is the tench’s nose of the Human being. Srrvoruns.—The walls of the uterus are composed of three membranes : an external, serous; a middle, muscular; and an internal, mucous; with vessels and nerves. The serous tunic envelops all the organ; it is an expansion of the broad ligaments, which are prolonged backwards on the posterior extremity of the vagina, and are afterwards doubled in a circular fashion around that canal, to pass over either the rectum, the bladder, or the lateral walls of the pelvis. Between the two cornua this membrane forms a particular frenum, which is but slightly developed in Solipeds. The muscular layer comprises longitudinal (superficial), and circular (deep) fibres, analogous to those of the small intestine. Near the insertion of the broad ligaments, they give off a series of fasciculi which are pro- longed between the two layers of these ligaments.. These are not the only muscular fibres met with in the ligaments, however; for Rouget has found others throughout their whole extent, but particularly in the vicinity of the ovaries. (Around the cervix uteri, the circular fibres are most dense and numerous. ) In the pregnant animal, the number of fibres composing this layer is much more considerable than in ordinary circumstances; and this increase has for its object to permit the dilatation of the uterus, without allowing its parietes to become too attenuated; they do become more or less thin, notwithstanding, according to the species. It has also been remarked that, during pregnancy, the muscular fibres present a manifest striation. (The elements of these fibres are short fusiform cells with long oval nuclei, mixed with a large quantity of immature nucleated areolar tissue.) The mucous membrane is thin, delicate, and raised into folds. It is covered by ciliated epithelium, which becomes cylindrical in the canal of the cervix, and pavemental around the os uteri. (The cilia vibrate towards the fundus of the organ. The membrane is closely connected with the muscular tunic, and is composed of immature nucleated areolar tissue without elastic fibres.) The uterine mucous membrane is destitute of pille (except at the cervix, where, according to Leyh, there are many ghly vascular papille); but it lodges numerous simple or ramified glands, which are straight or slightly flexuous at their extremities. At the cervix, these glands enlarge at the bottom, and assume something of the appearance of acinous glands. (These mucous glands are designated simple and cylindrical. The first are most numerous towards the cervix; some, here and there, with their orifices closed, are enlarged, and form small vesicular tumours, the ovula Nabothi ; they secrete the peculiar transparent mucus found here. The ' Unstriped contractile fibres are also found, in the male, along the spermatic cord» bi neath the visceral layer of the tunica vaginalis. *. 880 THE GENERATIVE APPARATUS. cylindrical, uterine, or wutricular glands are closely clustered together, sometimes bifurcated, often twisted in a spiral fashion, and terminating in a cul-de-sac in the. substance of the membrane. In structure they resemble other mucous glands, consisting of a membrana propria, an epithelium of spheroidal cells at the bottom of the tube, and of columnar cells in its duct. During gestation they are much enlarged, and receive the cotyledonal processes of the placenta. At the period of cestrum, the glandular secretion of the uterus is more active than at other times.) Vessels—Nerves.—The blood brought to the uterus by the uterine and utero-ovarian arteries, is conveyed from it by veins corresponding to the latter. In animals which have been pregnant several times, the vessels are remarkable for their enormous volume and their tortuousness, (The arteries freely anastomose; they ramify through the muscular and mucous tunics, constituting coarse and fine networks which ultimately end in the veins. These are very large and have no valves; the plexuses they form are considerable.) The lymphatics that pass from the uterus are as remarkable for their number as their dimensions; they reach the sublumbar region. ' The nerves supplying the organ come from the small mesenteric and pelvic plexuses. (In the uterus there are several important nervous gan- glia; and during gestation it has been ascertained that the nerves, like the vessels, enlarge, and after parturition return to their former size.) Deve.opment.—Narrow in the foetus, and in the adult which has not been impregnated, the uterus increases in size in animals which have had young several times. , Funotions.—The uterus is the sac in which the embryo is developed. The ovulum grafts itself upon the mucous membrane of the organ by its placental apparatus, in order to draw indirectly, from the maternal blood, the materials for its development. This function of the uterus gives rise to most interesting anatomical and physiological considerations, which will be referred to when giving the history of the ovum. 4, The Vagina. (Figs. 411, 412.) _ The vagina is a membranous canal with thin walls; it succeeds the uterus, and terminates posteriorly by an external opening—the vulva. ' Situation and Relations.—Situated in the pelvic cavity, which it passes horizontally across, the vagina is in relation with the rectum above, below with the bladder, and laterally with the sides of the pelvis and ureters. Loose connective and adipose tissue surround it posteriorly. Internal conformation.—The inner surface of the vagina is always lubri- cated by an abundance of mucus, and is ridged by longitudinal folds (co- lumne rugose). In front, at the bottom of the canal, is observed the projection formed by the cervix uteri ; posteriorly, this surface is continuous with that of the vulva. Srructurs.—The vagina is formed of two tunics; an inner, mucous, and an external, muscular. The mucous membrane (pale-red in colour) is con- tinuous with that lining the vulva and the uterus (and bladder); it is provided with papillw, and is lined by stratified pavement (squamous) epithelium, (It consists of connective and elastic tissue, to which its extensibility and firmness are due.) The muscular coat is rose-coloured, and traversed by a large number of vessels ; it is surrounded, for the greater part of its extent, by an abundance ~~ re a 881 THE FEMALE GENIPAL ORGANS. 22 ae 3.2 O-m* SE 0 a3 oO ELE = 5 ug 36 mal 5 21! a) Sez Pe - ibe pcg. ene ees aS Pr oe Bag + “E 38 “wujSua ay} Jo qing ‘9T £ Soupry ‘ey {umyooy oy} Surpunosins umouozsed Jo pyoy avpnomry ‘py fumpooy ‘gy {xezorg ‘ZT Srepperg “TT ‘snuv oq} jo aoqourydg ‘oT £0391p a10L10480g “Gg fBATNA oY} Jo 1OzOITySUOO JOFIeyUY “g t wurde, ‘, fyoyN xtAteD ‘g f queued] punor Arvj;UONT -tpny ‘¢ {queued}, peorg ‘p $yovq poyooy eqng oy} Jo uoyard oy} YIM ‘AreAQ ‘g ‘npyis Ul TUVK AHL AO SNVOUO TALLVEANG, "40 SANDNON ‘ tenusog ‘*g *% {snsoyn 043 Jo Apog ‘7 NBIIYOVIEIATA The mus- 84 al they are redder than in front.) , and arranged in circular and longitudinal series ; The vagina is supplied with blood by the internal the third or fibrous tunic of the vagina. iped towards the posterior portion of the can x5 | v5.8 2 SeEe bos * g a3 ar se 882 THE APPARATUS OF GENERATION. pudic artery; this fluid is carried from it by numerous veins, which are disposed in a plexus around the canal, and enter the satellite of the artery. The nerves come from the pelvic plexus. (The lymphatics accom- pany the veins, and pass to the pelvic glands.) Funorton.—The vagina receives the male organ during copulation, and through it the foetus passes during parturition. 5. The Vulva. (Fig. 411.) The external orifice of the vagina, the vulva is situated in the perineal region, immediately below the anus. We will consider in succession its external opening, its cavity, and its structure. Exrernat Orrninc.—This is a vertical elongated slit, presenting two lips and two commissures. The lips (labia vulve) are covered externally by a fine smooth, unctuous, and (almost) hairless skin, rich in colouring pigment, and lined internally by mucous membrane ; on their free margin, the limits of these two membranes are well marked. The superior commissure is very acute, and almost meets the anus, from which it is nevertheless separated by a narrow space—the perineum. The inferior commissure is obtuse and rounded ; it lodges the clitoris. Cavity or THE Vutva.—By all Veterinary authorities, this cavity is described as belonging to the vagina, to which it forms the entrance; but considering the analogies that exist between the genital parts of Woman and those of animals, this cavity must be distinguished from that of the vagina. It offers for study the hymen, which separates the two cavities, the meatus urinarius and its valve, and the clitoris. Tuer Crrroris.—Exactly similar to the corpus cavernosum of the male, which it represents in miniature, and 2 to 3 inches in length, the clitoris commences by two crura fixed to the ischial arch, and covered by a rudimentary ischio-cavernosum muscle. After being attached to the symphysis by means of a suspensory ligament analogous to that of the male, it passes backwards and protrudes into the vulvular cavity, towards the inferior commissure. Its free extremity, lodged in that cavity, is enveloped by a mucous cap—the prepuce of the clitoris (preeputium clitoridis), which is folded in various directions, and excavated about the centre of the tubercle by a small follicular cavity that represents the extremity of the male penis. The organisation of the clitoris resembles in every particular that of the corpus cavernosum of the penis: a fibrous framework, erectile tissue, and cavernous vessels. It is the contact of the penis with this organ during copulation that chiefly occasions the venereal excitation. Tue Meatus Unrarivs anp 1rs VAtve.—The urethral canal in the female is very short. It passes immediately beneath the anterior sphincter muscle of the vulva, and after a brief course in the texture of the floor of the vagina, it opens into the vulvular cavity by an orifice covered by a large mucous valve: this is the meatus wrinarius and its valve. The urinary opening, placed at the bottom of the cavity, at from 34 to 5 inches from the external opening, is wider than the male urethra, and will admit sounds of somewhat large calibre, for the catheterism of the bladder. The valve has its free border inclining backwards, to direct the flow of urine towards the exterior, and prevent its reflux into the vagina. (The female urethra is composed of two tunics: a mucous, continuous with that of the bladder and vagina; and a muscular coat, also a con- tinuation of that belonging to these organs, and chiefly made up of circular THE FEMALE GENITAL ORGANS. 883 fibres; some flat fasciculi attach it to the periosteum of the ischia. The urethra is not surrounded by a spongy body as in the male.) Tue Hymen.—This membrane, when it exists, distinctly separates the vulvular from the vaginal cavity. It is rarely present, however; though we have observed it several times in the adult Mare. It forms a circular partition, fixed by its margin to the vulvo-vaginal walls, as well as to the valve of the meatus urinarius, and is perforated by one or more openings which establish a communication between the vulva and vagina. On many occasions we have found, in old brood-mares, pediculated appendages, the remains of this septum. ' Srrverure or THE Vutva.—The vulva offers for study in its structure: 1, The mucous membrane lining its interior; 2, An erectile body lying on that membrane, and named the vaginal bulb; 3, Two-constrictor muscles— anterior and posterior ; 4, Two muscular ligaments ; 5, The external skin. 1. Mucous membrane.—Continuous with that of the vagina and bladder, this membrane has a rosy colour, which may become a bright-red at the period of heat. It often shows, near the free border of the labia, black pigment patches, which give it a spedi'ed appearance. It has in its substance a great quantity of mucous follicles and sebaceous glands. The latter exist near the free border, particularly about the clitoris, and es- pecially in the s between that erectile body and the inferior commissure of the vulva, where they meet in several small sinuses. (These glands secrete an unctuous matter possessing a special odour; they are most active during cestrum.) ; 2. Vaginal bulb—This is an organ entirely formed of erectile tissue with wide areole; it is divided into two branches (bulbi vestibuli), which arise from the vicinity of the crura of the clitoris and pass on the sides of the vulva, where they terminate in a round lobe. Covered by the posterior constrictor of the vulva, the vaginal bulb communicates, inferiorly, with the veins of the corpus cavernosum. The influx of blood into the cells of its tissue contracts the vulvular cavity, and concurs to render the coaptation of the copulatory organs more perfect during coition. 3. Muscles of the vulva.—Imperfectly described and determined in books on Veterinary Anatomy, these belong to the category of voluntary muscles. We recognise two, which will be described as the posterior and anterior constrictors. Posterior Consrricror oF THE VutvA.—Analogous to the constrictor ine of Woman, this muscle, included in the labia of the vulva, forms a veritable sphincter. Above, its fibres are mixed with those of the sphincter ani, and are attached to the sacrum through the medium of the suspensory ligaments. Inferiorly, the most anterior are fixed to the base of the clitoris ; the middle are prolonged to between the thighs, and are inserted into the inner surface of the skin. Inwardly, it is in relation with the vaginal bulb and the mucous membrane of the vulva. Its external face is separated from the skin of the labia by a very vascular cellulo-fibrous tissue capable of contraction, and in the midst of which are always found isolated fasciculi—dependencies of the principal muscle. This muscle, in contracting during copulation, constricts the aperture of the vagina and compresses the penis; and as, in consequence of its attach- ment to the clitoris, it cannot act without raising that erectile body, it applies this to the male organ and causes a greater degree of excitement. With animals in heat, the movements of the clitoris are frequently observed 3142 884 THE APPARATUS OF GENERATION. to propel that organ outwards, especially after micturation ; in this case, the fibres of the constrictor attached to the clitoris erect it by its base, while those which are fixed into the skin between the thighs depress the inferior commissure of tho vulva. This double action necessarily exposes the erectile tubercle lodged in that commissure. Anterior Constrictor or THE Vutvya.—Analogous to Wilson’s muscle in the male, this constrictor is formed of arciform fibres which enyelo below and laterally, the vaginal walls at the entrance of the canal; it extremities are continued, by means of aponeurotic fascia, to the sides of the rectum, where they are lost. By its posterior border, this muscle is mixed with the preceding. 4. Muscular ligaments of the vulva.—Traces of the suspensory cords of the male penis, these ligaments are disposed in the same manner at origin. After becoming united beneath the rectum, they descend in several fasciculi into the labia of the vulva, and disappear among the fibres of the posterior constrictor. 5. External skin—This is fine and black (or light-coloured), destitute of hair, smooth and unctuous, and adheres closely to the subjacent tissues. — 6. The Mamme. The mamme are glandular organs, which secrete the fluid that should nourish the young animal during the early months of its life. They are rudimentary in youth, and become developed with the advent of puberty, assuming their greatest development towards the end of gestation; they are most active after parturition, and cease their function, as well as diminish in volume, when the period of lactation has terminated. Situation.—These glands are two in number, placed beside each other in the inguinal region, where they occupy the situation of the scrotum in the male. Form.—They are two hemispherical masses, separated from each other by a shallow furrow, and showing in their centre a prolongation called the teat, nipple (dug), or mammilla, which is pierced at its free extremity by several orifices for the escape of the milk; it is by this prolongation that the young animal effects suction. The two glands are fixed in their position by the skin which covers them, and which is thin, black, covered with a fine down, and altogether destitute of hair in the vicinity of, or on, the teat, where the cutaneous surface is smooth, greasy, and supple. They are also attached to the tunica abdominalis by several wide, but short, elastic bands, which resemble the ligaments of the sheath in the male. Srrucrure.—Structurally, the mammary glands offer for study: 1, A yellow (elastic) fibrous envelope; 2, Glandular tissue; 3, The galactoferous reservoirs or sinuses ; 4, The excretory canals or mammary ducts, The elastic envelope, placed in the middle, beside its fellow of the opposite side, is mixed with the suspensory bands that descend from the abdominal tunic, and sends into the substance of the gland a number of septa, which are interposed between the principal lobules. The glandular tissue is a compound of gland vesicles or acini, clustered in groups around the lactiferous ducts. (The gland vesicles are made up of an amorphous membrane, membrana propria, lined with spheroidal nucleated cells. They are about 1-200th of an inch in diameter.) The lactiferous ducts commence by blind extremities, and run into each other to constitute er or THE FEMALE GENITAL ORGANS. 885 a certain number of principal canals ; these open into the galactoferous sinuses (each a sacculus vel sinus lactiferus). The glandular culs-de-sac are lined with a polyhedral epithelium, which becomes spherical and infiltrated with fat during lactation. Fig. 413. GLAND-VESICLES, WITH THEIR EXCRETORY ULTIMATE FOLLICLES, OR GLAND VESICLES, DUCTS TERMINATING IN A DUCTUS LAC- WITH THEIR EPITHELIUM OR SECRETING TIFEROUS: FROM A MERCURIAL INJECTION ; CELLS, a, 4, AND NUCLEI, }, b. MAGNIFIED FOUR TIMES. Placed at the base of the teat, the galactoferous sinuses or reservoirs are generally two in number, but sometimes-there are three, and even four; they nearly always communicate with each other, and are continued into the illa by an equal number of independent excretory canals—the definitive ducts, whose orifices are very small, and are seen beside each other at the free extremity of the teat. A fine mucous membrane lines the inner face of this excretory apparatus; it is doubled in the teat by a thick layer of tissue, which again is covered by the skin that adheres closely to it. (Between the external and internal tunic of the teats, are found numerous fasciculi of unstriped muscular fibres, arranged in a circular and longitudinal manner around these ducts.) Connective tissue, vessels and nerves, complete this organisation. (The arteries are from the external pudic trunk ; the veins are very numerous, and pass to the trunk of the same name; the nerves are derived from the first lumbar pair.) Fonorions.—The mamme secrete the milk; they undergo remarkable modifications at puberty and at the end of each gestation—modifications which are related not only to their volume and secretion, but also to their minute structure. After ges- tation, the gland-vesicles shrink: become, as it were, atrophied, and have only a polygonal epithelium. At the termination of gestation, they are enlarged, new vesicles are de- veloped, and the epithelium changes its r: filling the gland cavi- ties, assuming a spherical shape, and becoming ¢ ed With fat granula- yionoscoric APPEARANCE OP MILK, WITH AN tions. The period of lactation being irermrxrurne or coLosTRIC CORPUSCLES completed, the mamme take on their AT 4,4, AND ELSEWHERE. former character. (In Mares which have not been bred from, the mamma are hard and small, the teats but slightly prominent, and the glandular tissue scanty. In old brood-mares, - 886) , ie, THE APPARATUS OF GENERATION. on the contrary, they are flaccid and pendant, and the teats somewhat lengthened. The milk secreted by the mammary glands is a white fluid, possessing a sweet taste, and composed of an albuminous water containing caseine in solution, milk sugar, salts, and fatty matter in globules—the butter. Usually a small quantity is secreted some days before parturition ; that which is yielded for a short time after that period is named " it is rich in white corpuscles and has purgative properties, The colostrum is of a rich yellow colour, less fluid than the milk of a later of i f - . a higher specific gravity, slightly acid, and containing large oil-globules, a — few irregular flakes, probably epithelium scales, a little granular curd-like matter, and a small number of granular corpuscles.) DIFFERENTIAL CHARACTERS IN THE FEMALE GENITAL ORGANS OF OTHER THAN SOLIPED ANIMALS. Certain organs offer some differences worthy of notice, while others are formed as in Solipeds. UMINANTS.—Ovaries.—In the Cow, the ovaries are relatively much smaller than in the Mare, but their form and structure are identical. (The Graafian vesicles are visible through the tunica albuginea.) Uterus.—The uterus of the Cow, compared with that of the Mare, offers but few differences with regard to its general disposition in the pelvic and abdominal cavities, except that it is not so advanced in the latter. Supposing the uterus to be perfectly horizontal, a transverse line drawn through the plane of the abdomen, before the external angle of the ilium, is exceeded by the extremity of the cornua about 1} to 2 inches; so that if the animal were on its back, the uterus would be only prolonged to the fourth or fifth lumbar vertebra. : With regard to form, the uterus of the Cow pre-ents a very remarkable disposition, which it is necessary to note: the concave curvature of the cornua looks downw: while in the Mare it looks upwards; though in both the sublumbar ligaments are attached to this concavity. Therefore it is that in the Cow, if we consider the uterus as freely suspended in the abdomen, the extremity of the cornua is twisted outwards “and upwards, while the “base, although drawn in the same direction by these ligaments, maintains its direction, because it is in a manner fixed by the body of the uterus. The latter receives, like the cornua, the insertion of the broad ligaments on its lower plane, so that it overlaps them, while the uterus of the Mare projects below them. Otherwise, these ligaments are very ample, especially at their anterior border; they are wide apart in front, towards their lumbar attachment, which is prolonged even on the parietes of the flank, The ligaments may be altogether compared to a triangular cravat, one angle of which is attached to the bottom of the pelvic cavity, and the other two to the tuberosities of the ilium. On this cravat lies the body and part of the cornua of the uterus. The uterine cornua are thin and tapering at their anterior extremity. The body is short and narrow. The interior of the uterus of the Cow is less ample than that of the Mare. Its surface is studded with rounded tubercles, known as cotyledons, which will be studied hereafter. It is only necessary to say here that they are numerous in the cornua, but small and few in the body of the organ. The cervix uteri, about from 2? to 3} inches long, is narrow and irregular. The “expanded flower,” more finely plicated than in the Mare, is almost cartilaginous. Three other plicated rings, each smaller than the other, are échelonned in the cavity of the cervix, from the external orifice to the body (corresponding to the plic# palmata or arbor vitz uterina of Woman). In structure, the muscular layer is generally thicker than in Solipeds, In the 8 and Goat, the arrangement is the same as in the Cow, except that the cotyledons are hollowed like a cup in their centre, and deserve their name. (The cornua are longer and more pendent tlian in the Cow.) Vagina.—In the Cow, the sides of the vagina are traversed, for a certain distance, by a mucous canal that opens into the vulvular cavity, beside the meatus urinarius. These ducts, the use of which is unknown, are designated the canals of -Gertner. ‘hey are not present in the S/ or Goat. (In Ruminants, the vagina is longer and its external tunic thicker than in the Mare. Leyh describes the canals of Gertner as present in the Mare, though rarely.) Vulva.—This has thick lips in the Cow. The inferior commissure is acute, and THE FEMALE GENITAL ORGANS, 887 furnished with a tuft of hair. (The corpus cavernosum of the clitoris is longer, thinner, and more flexuous, and the gland much smaller than in the Mare.) é meatus whose which it is necessary to avoid in catheterism of the bladder. At about an inch from the to the vulva, there are found in the texture of the labia the vul nal glands (glands of Bartholine). Discovered by Duverney, described by oline, and ong al Colin,' these glands (two in number) are about the size of a large almond ; their extremity is directed upwards,and the narrow end, situated in the vicinity of the ischio-clitoridis muscle, gives origin to the excretory canaliculi. They are racemose, and their ducts unite to form a kind of sinus, which at length opens in the vaginal cavity, about 4 inches from the labia of the vulva. (These glandule vagina: are supposed to be analogous to the prostate glands, and are covered by cemiulan to They are composed of pyriform glandular vesicles, lined by squamous epithelium, and - surrounded by a dense nucleated connective tissue; the excretory ducts are invested by columnar epithelium, and surrounded by a thin layer of smooth muscle-cells, disposed itudi . Their secretion is a clear, yellowish, viscid mucus.) (In the Sheep and Goat, the labia of the vulva have several folds externally, and the inferior commissure terminates in a point.) Mammx.—In the Cow, each lateral mammary mass, although enclosed in a single ‘oferous sinus, the confluent of all the lactiferous ducts—a wide cavity 4 ey at the extremity of teat pa a definitive excretory canal. (The mamme of the Cow occupy the same region as In the 8. and Goat, there are only two mamme, as in the Mare and Ass, though aaa Goat has frequently two posterior anaes Pic.—The ovary of the Sow has a lobulated aspect, like the ovary of birds This is due to the ovisacs which, when they are well developed, project beyond Sar sentace cf the ovarium, instead of remaining encysted in its stroma. The oviduct is less flexuous, but its length is proportionately greater than in the other species. The body of the uterus is short, but the cornua are very long and folded, and float amongst the intestinal convolutions. (Its cervix does not project into the vagina and the two cavities, vagina and uterus, are continued into each other without any marked limit between them. The mucous membrane is very loose, soft, and fine to the touch, and its surface is up into numerous fulds of various forms, The broad ligaments resemble mesentery, and the cornua join the Fallopian tubes without any very limit ‘The inferior commissure of the ru/va is more acute than in Ruminants, mamme . are ten in number, disposed in two rows, extending from the inguinal region to below the chest. They have no galactoferous reservoirs, as in the larger Ruminants: the lactiferous ducts uniting directly into a variable number of definitive canals that pass through the teat, to pierce iis extremity by from five to ten orifices. (There are, of course, five or six ay in each row, each with its teat.) Carnivora.—In the and Cat, the ovaries and uterus are disposed as in the Pig ; the ovaries (are situated behind the kidneys, age Reo lodged in a particular fold of the i nts, which forms a kind of cup. ere are no Geertner’s canals in the vagina, The vulva of the Dog is trian , and acute at its inferior commissure. The Cat has a small bone in the clitoris. The mamme are ten in number in the Dog, and cight in the Cat; they are distinguished, as in the Pig, into inguinal, abdominal, and | bes Fach teat has from eight to ten orifices. e vagina is long, and wider at vulva towards the uterus. Beside the smooth muscular fibres of its external | coat, it has white fibres which give it greater thickness and resistance. The mucous membrane forms longitudinal, intersected by transverse, folds; the yalve of the meatus urinarius searcely exists. The cervix of the uterus a eey into the vagina, and is even more yoluminous than the body, which is short; it is hard to the touch.) ' «Traité de Physiologie Comparée des Animaux Domestiques.’ Paris, 1871. } iy % 888 THE APPARATUS OF GENERATION. COMPARISON OF THE GENERATIVE ORGANS OF WOMAN WITH THOSE OF ANIMALS. Ovaries.—These organs are oval, about 14 inches long and 8-10ths of an inch broad, and are lodged in the posterior layer of the broad ligaments. They are attached to the uterus by the ligament of the ovary, and united to the Fallopian tubes by the fps ovarian ligament. Their structure is the same as in animals. A Graafian usually ripens every month; its rupture corresponds with the menstrual Annexed to the human ovary is found the organ of miiller, composed of from fifteen to twenty tortuous tubes opening into a transverse branch ; these tubes are lined by ciliated epithelium, and filled with a yellow fluid; they form a closed system included — in the broad ligament, between the ovary and oviduct. Oviduct.—Placed at the upper border of the broad ligament, it is nearly straight, and terminates by a pavilion notched into about fifteen unequal fringes. Uterus —The human uterus is situated between the bladder and rectum, being inclined Fig. 416. rr UTERUS WITH ITS APPENDAGES, VIEWED FROM THE FRONT. 1, Body of the uterus; 2, Fundus; 3, Cervix; 4, Os uteri; 5, Vagina, with its columna and transverse ruge; 6, 6, Broad ligament of the uterus; 7, Convexity of the broad ligament formed by the ovary; 8, 8, Round ligaments of the uterus; 9, 9, Fallopian tubes; 10, 10, Their fimbriated extremities; 11, Ovary; 12, Utero-ovarian ligament; 13, Fallopio-ovarian ligament; 14, Peritoneum of anterior surface of uterus; it is removed at the left side, but on the right is continuous with the anterior layer of the broad ligament. slightly downwards, from before to behind. Its form is very different from the uterus of the animals we have described, being that of a flattened gourd; its volume varies with — age and the number of gestations; it weighs about two ounces. It is described as haying — a body and cervix. The body is triangular, and at the extremities of its upper border the oviducts open into it. The cervix is fusiform ; the projection it makes at the bottom of the vagina is the tench’s nose—a transversal slit bordered by two unequal lips. The inner face of the cervix shows the plic# palmate, arborisations formed by the mucous membrane. There is nothing special to be noticed in its structure. The broad ligaments comprise a quantity of muscular fibres between their layers, and which accumulate at certain points to form accessory folds; among these the most important are the round ligaments. These leave the anterior face of the uterus, pass forward and outward, enter the inguinal canal, and terminate in the connective tissue of the mons Veneris. Vagina.—This canal is about 23 inches wide; it is in contact with the rectum, and responds in front, by connective tissue, to the bladder and urethra. Its internal face has longitudinal folds, the columnax of the vagina, which are intersected by transverse folds. ow the orifice of the urethra is the entrance to the vagina, a cire opening partially closed by the hymen in virgins. Rarely complete, this membrane may affect different shapes, and consequently receive various names, as horse shoe, bilabial, semilunar, annular, and fringed hymen. When ruptured, it retracts very much, but there always remain some vestiges of it, and which are designated caruncul# myrtiformes. Vulva.—This presents a cavity an! an orifice, as in the domesticated animals; but the cavity is not so deep, and is named the vestibule; it extends to the hymen or its débris. The entrance to the vulva occurs in the middle of a cuneiform prominence which is confounded, above, with a kind of eminence, the mons Veneris, which appears to protect the pubic symphysis. It is margined by two folds: one cutaneous, the labia THE GENERATIVE APPARATUS OF BIRDS, 889 majora; the other mucous, the labia minora (or nymphx). The labia majora are convex externally, continuous above with the mons Veneris, and unite below to form an acute angle, named the Guendites they are covered externally with hair. The labia minora, more or less develo leave the tourchette, and extend around the entrance to the vagina, ang above the clitoris, and forming the —— of that organ. The elitoris is lodged in the superior commissure of the vulva; its point is directed downwards, especially during erection; its base is attached,on each side, to the two erectile lobes which constitute the bulb of the vagina (bulbi vestibuli). Two racemose glands, the vulvo-vaginal or glands of Bartholine, pour their secretion over the walls of the vestibule. Mammzx.—These are pectoral, and two in number. In their centre, they present an enormous —the nipple —into which the excretory canals open ; it is surrounded by a brown circle, the areola of the nipple. CHAPTER ITI. GENERATIVE APPARATUS OF BIRDS. > ~ 1. Male Generative Organs. Tue generative organs of the male are the testicles, and an excretory apparatus much than that of mammals. ‘esticles.—These or, are placed in the sublumbar region of the abdominal cavity the and below the anterior extremity of the kidneys. Their form is 1 oval, and their volume varies with the different species, as well as at different ; at the breeding season they are greatly developed. Exeretory Apparatus.—In birds there is not, properly speaking, any epididymis. The deferens passes from within the posterior extremity of the testicle, is directed in a flexuous manner backwards, draws near to the ureter on its own side, going along the kidney with it, and arriving at the cloaca, where it terminates by an orifice to be alluded to hereafter. In the Duck, it has near its termination a small oval vesicle, always filled with spermatic fluid. a of Copulation.—This varies with the species. In the Gallinace, it is only a papilla placed below, néar the margin of the cloacal opening, and between the two orifices of the deferent canals. ‘This papilla is traversed by a furrow through which the semen flows. In the eee Se is organ is much more anvtlibet and is peculiar. Contained within a tubular cavity in the cloaca, it is protruded externally at the moment of copulation by the eversion of this cavity, like a finger out of a glove; it then appears as a long pendant appendage, twisted like a cork-screw. 2. Generative Organs of the Female. The development of the young animal taking place external to the female, the generative organs are limited to that producing the ovum, and the duct through which it passes on leaving the ovary. Ovary.—In birds there is only one ovary, which is situated on the left side, the right one peg See very early in nearly all species. This ovary is situated, like the testicles, in the sublumbar region of the abdominal cavity, and constitutes a more or less voluminous body, com of a variable number of ovules in process of development : some very young, little, and white; others more advanced in age, being larger and yellow in colour, The ova are enveloped in a very vascular cellular membrane, which, when they are ripe, splits in a circular manner, following an equatorial line, and permits the escape of the essential part of the egg —the yellow (yelk), or vitellus. Oviduct.—This duct is long, very wide and dilatable, and very flexuous. It begins, near the ovary, by an unfringed pavilion, and terminates in the cloaca by a somewhat narrow orifice, which is considerably widened when the egg passes through it. The egg, composed, on entering the oviduct, of the fandamental part named the yelk, or vitellus, is enveloped in an albuminous sphere during its progress towards the cloaca, and after- wards with a protecting shell. The oviduct of birds is, therefure, something more than an excretory canal, as it participates in the formation of the ovum. It is composed of three membranes: an ezternal, serous, maintains the tortuous tube; a middle, muscular; and an internal, mucous. ; BOOK IX. EMBRYOLOGY. Empryo.oey has for its study the modifications to which the ovulum is submitted, from the moment when it is fecundated until it is transformed into a new being capable of living in the external world. The points of this subject belonging to the domain of anatomy, will be divided into three chapters. In the first, the transformations of the ovalum which produce the ovum and embryo will be examined. In the second, the various portions of the ovam—the annexes of the foetus—will be studied ; and the third will be occupied with the development of the foetus. CHAPTER I. THE OVULUM AND ITS MODIFICATIONS AFTER FECUNDATION. Articte L—Tue Ovuivm. Tue ovulum of the domestic mammifers is a vesicle about .J55 of an inch in diameter (the germinal spot being from 355 to gqyy of an inch), contained in the ovisac, in the midst of the cumulus proligera. It possesses all the elements of a complete cell, comprising: 1, An amorphous, trans- parent enveloping membrane, named the vitelline membrane, or zona pellucida ; 2, A hazy viscous fluid, holding in suspension a large number of dark granulations and fat globules: this is the vitellus or yelk; 8, The ger- minative vesicle, a spherical, transparent nucleus lying to one side of the vesicle, and readily altered; 4, The germinal spot, a kind of very brilliant nucleolus seen in the centre of the nucleus. According to Balbiani, there also exists in the ovulum of all animals, from insects up to mammals, beside the germinative vesicle, a second nucleus—named Balbiani’s or the embryogenous vesicle—which plays a very important part in the nutrition of the ovulum and the phenomena succeeding fecundation. Artictxy I].—Moprrications in THE OvuLUM UNTIL THE APPEARANCE OF THE Empryo. These include the segmentation of the vitellus, the formation of the blastoderm, and the appearance of the embryo. 1. SeGMENTATION oF THE ViTELLUSs.—Several times spermatozoa have been seen in the vitelline zone of the fecundated ovulum. This fact is merely alluded to, as we have to speak of the consequences of fecundation, and not sal THE FQ@TUS. 891 of fecundation itself. After it has taken place, the germinal vesicle is not perceived ; has it disappeared, or changed its character if it does yet exist ? This question cannot be answered; all that is known is that it has ceased to be visible. Then the contraction of the vitellus begins; it leaves its enveloping membrane, becomes depressed in a circular manner, and ends by forming two independent masses, each provided with a nucleus. These two globes of segmentation (or cleavage marses)—for such is the name given to Fig. 417. PROGRESSIVE STAGES IN THE SEGMENTATION OF THE YOLK OF THE MAMMALIAN OVUM. A, Its first division into halves, with the spermatozoa around its circumference; B, Subdivision of each half into two; c, Further subdivision producing numerous segments. them—are, in their turn, divided into other two globes, the number now being four. These four are once more divided, and these again subdivided, until the whole mass of the vitellus is completely transformed into globules (or embryo-cells), composed of a nucleus covered by a thin membrane. Fig. 418. LATER STAGE IN THE SEGMENTATION PROCESS. A, Mulberry mass formed by the minute subdivision of the vitelline spheres; B, A further increase has brought its surface into contact with the vitelline membrane, against which the spherules are flattened, This is the segmentation of the ovulum: an operation that is always preceded by the retraction of the vitellus, and the appearance of one or two small globules about the point where it commences to be depressed; these Robin has designated polar globules. 892 EMBRYOLOGY. 2. Formation or THE Biasroperm.—Soon a fluid is formed at the centre of the ovulum, in the midst of the mass of vitelline globules, or rather the mass of young cells that take the place of the vitellus. This fluid presses the globules outwards against the inner face of the vitelline membrane, and the pressure increasing as it augments, these become flattened like the elements of pavement epithelium, until, finally, they constitute a membrane lining the zona pellucida. This is the blastoderm. The blastodermic vesicle (as it has been termed) does not remain — simple, but soon divides into two layers: an eaternal and internal blas- todermic layer, which are readily recognisable, as the elements of the first are pale or slightly granular, while the cells of the second are filled with fat granules, and consequently are less distinct and darker coloured. 3. APPEARANCE oF THE Empryo.--While the blastoderm is dividing into layers, there is observed another modification taking place in the oyulum, from which results the first lineaments of the embryo. As soon as the blastodermic vesicle is formed, a small round thickening takes place at a point of its surface, due to a multiplication of cells. This mass destroys the transparency of the blastoderm, and is designated the embryonic spot or area germinativa. ; The area germinativa is the centre where commences the separation of the blastoderm into external or internal layers. The middle layer, which is to form the foetal organs, does not extend beyond this area. By a proliferation of the elements of the external and middle layers, the area germinativa increases in surface and thickness; it becomes dark, prominent, and buckler-shaped, and is named the opaque area ; this is soon transparent in its centre—the area pellucida. The area pellucida becomes elongated and constricted in its middle to form the embryonic area; in the middle of this appears a dark line, the primitive trace or furrow, and below is perceived a round cord—the chorda dorsalis—which develops the spinal axis. The inner layer, in its turn, becomes two layers at the point cor- responding to the embryo, and this gives rise to the middle layer. In fine, towards the twelfth day after fecundation, the ovum, having arrived in the uterus, measures from 54,th to 54,th of an inch in diameter, and is composed of four shells contained one within the other, three of which are complete, viz: 1, The zona pellucida; 2, The external layer of the blastoderm; 3, The middle layer; 4, The internal layer. At this time the first membrane, destined to become the chorion, is already studded with fine villosities. ArtioLe III,—Dervre.orment or THE BiastopERMIO LAyeEnrs. By ulterior metamorphoses, the layers of the blastoderm give rise to the annexes of the foetus and its various organs. Therefore it is that these layers receive other names than those which designate their situation. Thus the external, or serous, is named the sensitive layer, because it forms the skin and organs of sense; the middle is the vascular or germinative, as it contains the principal vessels of the embryo, and in its substance are developed the organs of locomotion; lastly, the internal layer is termed the mucous or intestino-glandular, in consequence of its constituting the mucous membranes, and its chief portion forming the intestines and their glands, Each blastodermic layer, then, in becoming developed, furnishes the intrafcetal and extrafoetal parts. We will study this development, having — THE FQ@TUS. 893 the extrafcetal parts particularly in view, and reserving the others until we come to examine the development of the foetus. EXTERNAL LAYER. a. Intrafetal parts—The external or sensitive layer (serous stratum- epiblast) forms several parts belonging to the foetus; these are: 1, The i is and its dependencies, such as the hair, hoofs, horns, glands of the in; 2, The central nervous system : the organs of the senses, such as the retina and the labyrinth. b. Extrafetal parts.—So long as the foetus is represented by a kind of shield at a given point of the blastodermic layers, the external layer is everywhere continuous, and extends to the inner face of the chorion and the surface of the embryo without any line of demarcation. But the embryo soon becomes inflected at its two extremities; the external layer of the blastoderm is depressed so as to give rise to two layers: the cephalic hood, which covers the cephalic extremity, and the caudal hood, which envelops the other extremity of the embryo. The lateral parts of the foetus also become inflected towards one another, as may be proved by a transverse section; thus closing-in, laterally, the thoraco-abdominal cavity of the young creature which, during this move- ment, is more deeply placed in the serous layer. The latter soon comes into contact with itself, above the back of the embryo. A short pedicle, the superior umbilicus, unites the two portions of the blastodermic layer. This pedicle is not long before it becomes obliterated, then breaks, when the foetus is found to be inclosed in an independent sac, which is nothing more than the amnion. Fig. 419. TRANSVERSE SECTION THROUGH THE EMBRYO OF THE CHICK AT THE CLOSE OF THE FIRST DAY OF INCUBATION; MAGNIFIED ABOUT 100 DIAMETERS, ch, Chorda dorsalis; A, External serous, or corneal layer; m, Medullary position of serous layer; Pv, Primitive groove between the dorsal laminw, Rf and m; dd, Intestinal epithelial, or glandular layer (mucous layer); wwp, Prevertebral mass, in which the primary, or protovertebra, are formed, and which is continuous with the middle lamina, sp; wwh, Fissure in the middle lamina, presenting the first indication of the pleuro-peritoneal (thoraco-abdominal) cavity, and of the subsequent division of the middle lamina into two layers. The sensitive layer is therefore resolved into two sections: an internal, the amnion ; and an external, the serous vesicle (false amnion of Pander, the serous covering of Von Baer), which is applied to the inner face of the zona pellucida, and concurs in forming the chorion. MIDDLE LAYER. All the parts to which the middle layer gives rise, belong to the organs of the foetus; the development of this layer will be more appropriately studied in the chapter devoted to the foetus. Sot EMBRYOLOGY. INTERNAL LAYER, a. Intrafeetal parts—The mucous layer of the blastoderm forms the epithelium of the intestines, the glands annexed to them, the respiratory apparatus, the kidneys, and the bladder. These organs are developed at the same time as the extra foetal portions, and will be referred to presently. b. Extrafoetal parts.—In incurving on itself, the embryo incloses in its cavity a portion of the internal blastodermic layer. The union between the free and the imprisoned portions is extensive; but before long it is only represented by a narrow canal that occupies the inferior umbilical ring. The mucous layer is then divided into two distinct portions: the intestinal groove, or intrafcetal portion; and the umbilical vesicle (vesicula alba), or extrafcetal portion; they communicate by the omphalo-mesenteric or vitelli duct. Fig. 420. Fig, 421, < DIAGRAM OF OVUM AT THE FORMATION PLAN OF EARLY UTERINE OVUM. OF THE AMNION. ~ Within the external ring, or zona pellucida, a, Chorion; b, Yolk-sac; c, Embryo; d ande, are: the serous lamina, a ; the yolk, b; and Folds of the serous layer rising up to form the incipient embryo, c. the amnion. The umbilical vesicle is filled with a granular fluid, which is conveyed, for the nutrition of the foetus, by the omphalo-mesenterice vessels. When this alimentary reserve is nearly expended, the allantois appears. ! The allantois commences by a small enlargement, which is thrown out by the intestinal furrow on the inferior abdominal wall. This bud becomes elongated, and gradually enlarges by drawing the umbilical vessels to its border: appearing as a small vesicle that at length extends through the umbilicus, and spreads itself over the inner face of the chorion, between it and the amnion. This new organ is divided into two sacs by a neck—the urachus—at the umbilical ring; the internal is the smallest and forms the bladder, and the external, the most voluminous, constitutes the allantois proper. Se ee THE FQTUS. 895 CHAPTER II. THE F@TAL ENVELOPES OF SOLIPEDS. We have seen, in the preceding chapter, that the vitelline membrane lined by the serous vesicle forms a complete shell around the developing ovum; and we have also noted that the layers of the blastoderm, in becoming meta- morphosed, constitute three membranous sacs, which contain the foetus. various membranes are described as the envelopes or annexes of the foetus. There are also added to these the cord of vessels and the capillary ramifications which establish the relations that exist between the mother and the young creature. The annexes of the foetus comprise: 1, A membranous envelope exactly moulded on the uterus, and known as the chorion; 2, A second ovoid sac included in the first, and directly containing the foetus: this is the amnion ; 8, The allantois, a membrane formed of two layers spread over the inner surface of the chorion and the external face of the amnion, as well as covering the parts between these two envelopes; 4, A small pyriform bladder constituting the umbilical vesicle ; 5, The placenta, a collection of vascular tufts which graft the young creature to the mother; 6, The umbilical cord, composed of vessels that attach the foetus to the envelopes surrounding it, and which ramify in the placental tufts. 1, The Chorion. (Fig. 422.) The outermost envelope of the ovum, the chorion is a vast membranous and perfectly-closed sac, whose shape exactly corresponds to that of the uterus. Fig. 422. EXTERIOR OF THE CHORIAL SAC; MARE. A, Body; B, c, Cornua. Tt has a body and two cornua. The latter, when inflated, are plicated and bosselated like the ewcum, and are always unequal in volume: that in which the foetus is developed having by far the largest dimensions. The external face is studded with small red tubercles, formed by the a "9 896 EMBRYOLOGY. placental tufts. It adheres to the internal surface of the uterus. Between ‘the two membranes there is found a small quantity of sanguinolent fluid. ; The internal face, lined by the external layer of the allantois, is united in the closest manner to that membrane, except at the umbilical cord, where there exists a kind of conical infundibulum occupied by the umbilical vesicle, Srrvoture.—The chorion is a delicate fibrous membrane, traversed by the vascular ramifications of the placenta. It is formed by the vitelline membrane, to the inner face of which the serous vesicle is applied. It is stated that the zona pellucida, or primitive chorion, as it is called, disappears when the serous vesicle, the definitive chorion, becomes Fig. 423. independent of the amnion. The chorion is destitute of vessels until the allantois is developed. EEE 2. The Amnion. (Figs. 423, 424.) The second sac enveloping the foetus, the amnion floats freely in the interior of the chorion, to which it is only united at one point through the medium of the umbilical cord. It contains the young creature, FECUNDATED EGG, SHOW- which is also attached to its inner face by the vessels ING FORMATION OF AM- NION AND aLLantors, Of the cord. It is oval in shape, and has thin trans- a, Umbilical vesicle; 6, parent walls. Amniotic cavity ; c, Al- Its external face is covered by the inner layer of lantois. the allantois, to which it adheres slightly. The internal face is perfectly smooth, and is applied more or less directly to the skin of the foetus. It exhales a fluid in which the latter floats—the liquor amnii. Liquor amnii—Inclosed with the fcetus in the cavity of the amnion, this fluid is more or less abun- dant, according to the period of gestation ; its relative quantity being always less as the foetus is advanced in development. At an early period it is somewhat milky in appearance, but later it assumes a citrine or slightly reddish tint. It has a salt taste, and con- tains 99 per cent of water, with albumen aud salts, the principal of which are chloride of sodium and the sulphate and phosphate of lime. Fig. 424. FECUNDATED EGG OF FOWL 8. The Allantois. (Fig. 423.) WITH ALLANTOIS NEARLY 2 COMPLETED. The allantois is a membrane that covers the inner a, Inner lamina of am- face of the chorion, and is folded around the insertion niotic fold; 0, Outer of the umbilical cord, to spread itself over the whole lamina of the same; c, . Point where the amnio- Xternal surface of the amnion. It thus transforms tic folds come in contact the chorial sac into a kind of serous cavity, in which with each other; the the amnios is inclosed as a viscus. peri reek a 98 The inner, or amniotic lamina, is attached to the inner and outer lamine ®™Mnios “so sliguey, that dissection, and especially of the:amniotic fold. insufflation, easily destroys its adhesion. When the second of these measures is resorted to, in order to separate the two membranes, the allantoid surface assumes a bosselated a. ee yeu, a ~~ ae ae ad rere aL THE FQTUS. 897 or blistered ap ce, due to the numerous cellular bands that attach it to the amnion. These bands rupture when the inflation is forced, and a noise is heard analogous to that produced by the rumpling of parchment. With a little care, the whole of this portion of the allantois, whose extent equals that of the amnion, may be entirely detached. “The degree of adhesion of the chorial allantois is more marked. Ordinary dissection, which is easy alorg the first divisions of the cord, is much more difficult towards the chorion, and soon becomes, if not im- ible, at least very arduous, if we desire to separate it. But here, again, inflation demonstrates the existence of the membrane, and its continuity with the portion so easily dissected from the amnion. If, after opening the allantoid sac by cutting through the chorion and the lamina lining it, a tube is introduced between the two membranes—which is readily done near a large vessel, by a slight inflation the air enters between the allantois and chorion, though it only follows the track of vessels of a certain size, to the sides of which there is but little adherence. If the inflation is pushed, the air, following the smallest vascular ramifications, renders the membrane more apparent, though without detaching it from the points where the vessels have almost become capillaries. “Tf, instead of injecting the air towards the ramifications, it is directed in the opposite direction, it will soon be perceived to extend towards the allantoid portion of the umbilical cord, and insinuate itself between the amnion and the allantois covering it: an evident proof of the continuity of the two layers which have been separated for the purpose of studying them, but which are, in reality, only two portions of the same membrane that forms a complete sac.” ! _ The cavity of this sac communicates with the bladder by means of the urachus, a narrow canal contained in the amniotic portion of the umbilical cord, and expanding towards the origin of the allantoid part (at p, Fig. 425), where its walls are continuous, one part with the amniotic layer of the membrane, the other with the chorial layer, after being prolonged as a sheath around the cord (zs). This arrangement shows the true character of the allantoid cavity, which is evidently a kind of urinary reservoir, a dependency of the bladder, whose fundus is prolonged to the umbilicus to constitute the urachus. The latter follows the umbilical vessels in the amniotic portion of the cord, and soon expands in forming the allantoid cavity. Srructrure.—The allantois arises from the intestinal furrow, or otherwise the included portion of the internal blastodermic lamina. It comprises a slightly fibrous framework, and an epithelial layer. It carries the umbilical vessels to its surface, from the umbilicus to the chorion. Ataytor Fium.—This cavity contains a fluid analogous to the liquor amnii, and which has almost the same physical qualities. Analysis demonstrates that, during the early months of fetal life, this fluid contains a somewhat large proportion of sugar; this gradually diminishes, and at last disappears altogether. The fluid has been considered, towards the termina- tion of gestation, as the urine of the foetus. Hirromanes.—This name is given to small brown masses, more or less numerous—though often there is only one—which float in the allantoid fluid. “These bodies, of the consistency of gluten, and elastic like it, are flattened, thinner at the borders than towards the centre, oval or irregularly circular, and about the diameter of a five-franc piece. It is difficult to explain the 1 F. Lecog. ‘Des Annexes du Foetus.’ 3 M 898 BMBRYOLOGY, presence of the hippomanes in the allantoid sac. Nothing in its appearance indicates that it may be formed at the expense of the liquid contained in this — membrane. Sometimes pediculated hippomanes are found, and these may assist in explaining the formation of the free hippomanes. Bourgelat speaks in his ‘ Anatomie’ of pediculated hippomanes, and I have been able to make the following observations, through having met with a large number on a fostus : FULUS OF THE MARE WITH ITS ENVELOPES, A, Chorion; c, Amnion removed from the allantoid cavity, and opened to expose the fetus; D, Infundibulum of the urachus; B, Allantoid portion of the umbilical cord.—b, Point of the external surface of the chorion, destitute of placental villi, and corresponding to the part where the three pediculated hippomanes are attached, “ Besides the free hippomanes found floating in the allantoid fluid, there were remarked, on the outer wall of the sac, a great number of small tear- shaped bodies of variable size, adhering by a pedicle which was more or less narrow as the mass was more developed. ‘I‘heir colour was the same as THE FQTUS. 899 that of the principal hippomanes, and if pressed between the fingers, the brown matter contained in a thin-walled sac escaped by the pedicle, and : itself over the external surface of the chorion. There the villosities ore were absent at the margin of the opening, which was ed by a whitish areola (Fig. 425, b). * Might it not be admitted, from this disposition, that the hippomanes is developed between the placenta and tue uterus, and is carried inward, by pushing before it the chorion and layer of the allantois covering it, until, on reaching the allantoid cavity, it becomes detached, like certain fibrous or cartilaginous bodies in the synovial or serous cavities ?”—F. Lecog. 4, The Umbilical Vesicle. The umbilical vesicle is a small fusiform or pyriform pouch, lodged in the infundibulum at the extremity of the umbilical cord. Its fundus adheres to the chorion; the opposite extremity is prolonged to a variable depth in the substance of the cord, and is even continued, in the very young foetus, to the abdominal cavity, by a narrow canal that communicates with the terminal portion of the small intestine. This pouch has a red colour, from its great vascularity; its walls receiving a special artery derived from the anterior mesenteric, the ing vein passing to the portal vein. These are the two omphalo- mesenteric vessels. Tn the last months of foetal life, the umbilical vesicle is always more or less atrophied ; its cavity has disappeared, and it is no more than a thin reddish-brown cord. Its vessels also become atrophied in the same manner, = nearly always nothing is found but the artery reduced to the dimensions a thread. 5. The Placenta. In Solipeds, the placenta is composed of a multitude of small tubercles, spread uniformly over the external surface of the chorion, which they almost completely cover. These small tubercles are formed by an ion of extremely vascular illi, which implant themselves in the follicles of the uterine mucous membrane. The terminal ramifi- cations of the vessels of the cord constitute the vascular apparatus of these villi (Fig. 426). a Sraverurns.—The villosities of portion or THE ULTIMATE RAMIFICATIONS eae planente are composed of & OF THE UMBILICAL VESSELS, FORMING THR quantity of delicate nu- TAL VILLI OF THE PLACENTA. cleated connective tissue (and a basement membrane), covered by simple epithelium; at their centre, they t the capillary ramifications of the vessels of the cord, which generally orm loops that return towards the base of the papilla (Fig. 427). The villous tufts penetrate the maternal uterine mucous membrane, in such a manner that the two capillary systems of mother and fetus are only separated by the very thin walls of the vessels and the tt of the M 900 EMBRYOLOGY. villi. The fusion of these two systems has never been observed, and all the interchanges between the female and its young take place through the capillaries by osmotic force only. 6. The Umbilical Cord. The cord is formed by the vessels which, in the footus, carry the blood to the envelopes, and chiefly to the Fig. 427, placenta, It is divided into two portions: : an amniotic, the longest, which is always twisted on itself like a cord, and covered externally by the amnion that is prolonged on its surface, to be continued with the skin around the umbilicus; the other, the allantoid portion (Fig. 425, B), much shorter and less twisted, is enveloped by the sheath that continues the two laminw of the allantois, and is inserted into the supe- rior wall of the chorion, between the two cornua. Three vessels compose the cord: two arteries and a vein; these are covered by a layer of embryonic tissue, the gelatine of Wharton, which makes them appear much larger than they really are. The Umpmicat Arrertes arise from the internal iliac, and pass along the sides of the bladder; escaping by the umbilicus, they arrive at the terminal extremity of the amniotic portion of the cord, and giving off some branches to the amnion, they are continued to the extremity of the allantoid portion, where they end in an ee oo ron Pant oF mip pra, €Xpansion of placental ramifications. The cums eae ceppetiiel i risigicane verte! . these ae are ue ew, and extremely flexuous; they are in- - Ieoped ai atin Tae be ea cluded between the allantoid layer and the nective tissue. amniotic membrane, within which they may be seen. The placental or chorial divisions, infinitely larger and more numerous, leave the end of the cord, and pass in every direction between the chorion and external lamina of the allantois, beneath which they project. By their anastomoses they form a very rich network, from which proceed the capillary twigs that enter the villosities of the placenta. Observation demonstrates that these twigs do not communicate with the maternal vessels, and that they are continued by venous radicles, the origin of the following vessel. The Umerican VeIn commences by these capillary radicles of the placental villosities, which unite between the chorion and amnion to form a network of more voluminous divisions and complexity than that of the arteries. Two principal branches are, finally, the result of the coalescing ; and these soon unite into a single trunk, which accompanies the two arteries in the cord. On reaching the umbilicus, this, the umbilical vein, bends forward on the inner face of the abdominal parictes, where it is ee i i i a el THE FUTUS. 901 covered by the peritoneum, and arrives at the liver, into which it enters and opens directly into the vena porte ; the junction of the two vessels giving rise to a single canal from which proceed the hepatic veins. In other animals than Solipeds, this vessel gives off a particular trunk of somewhat Fig. 428, A FETUS OPENED ON THE LEFT SIDE TO SHOW THE COURSE OF THE UMBILICAL VESSELS IN THE BODY. A, Umbilical cord; 8, Umbilical vein; c, Umbilical artery; p, Bladder; x, Testicle; F, Kidney; G, Spleen; u, Liver; 1, Intestine; J, Lung; K, Heart; L, Pulmonary artery; M, Ductus arteriosus; N, Thymus gland. considerable volume, which passes directly to the posterior vena cava, forming what is named the ductus venosus (Figs. 429, 430). Such are the umbilical vessels, and it will be seen that they form a part of the circulatory system of the young creature which will be more com- pletely studied hereafter. DIFFERENTIAL CHARACTERS IN THE ANNEXES OF THE FETUS OF OTHER THAN SOLIPED ANIMALS, 1, Ruminants.—Placenta,—The placental apparatus of the Cow is not uniformly spread over the outer surface of the chorion, but is constituted by a variable number of vascular bodies, about sixty on an average, disseminated here and there, and dovetailed by reciprocal penetration of prominences and cayities, into analogous bodies on the inner ace of the uterus, designated cotyledons. These are only thickened points of the mucous membrane, the follicles of which are enormously enlarged. They exist, we have seen, before gestation ; but observation demonstrates that they may be afterwars formed or entirely renewed, especially in those cases in which accidental circumstances have rendered those present insufficient for their office. The largest are found in te body of the uterus; in the cornua they are smaller as they are nearer the extremity. Their form is generally elliptical, and they are attached to the uterine surface by a wide mucous 902 EMBRYOLOGY. L224, ACRERB AOL Rad nab. De BLOOD-VESSELS IN THE LIVER OF AN EQUINE FCTUS AT MID-TERM, A, Umbilical vein; B, Its anastomoses with the portal vein, ¢; D, Ductus venosus; E, Posterior vena cava. Fig. 430, LIVER OF A LAMB AT BIRTH, A, Posterior vena cava; B, Vena porte; ¢, Umbilical vein; p, Anastomosis of the umbilical vein with the vena porte. THE FETUS. 908 ; their surface is convex, and perforated by numerous openings, into which the al tufts pass. They have always a yellowish colour which, added to their mal characteristics, gives them the appearance of a moril mushroom. ith regard to the placentz, «Be sa Bes rhe niet ct eco -mreir Serle ye __ of the cotyledons on the uterus. They are vascular, concave patches, siosely em g © cot, ons, and showing on their surface a multitude of long ramifying papillw, which bury themselves in the cotyledonal cavities. They are attached to the chien by sk, short, vascular pedicle. c rh villa and Goat the arrangement is the same, except that the cotyledons are __ hollowed out in their centre, like a cup, and into this cavity the placenta is inserted. — ‘¢. Chorion—This membrane corresponds to the inner face of the uterus, in the inter- plac paral its internal surface is united by lamellar connective tissue to the ; allantois. Its general form is a repetition of that of the uterine cavity. —Very different from that of the Mare, and otherwise much less com- _ Umbilical vesicle—This pouch disappears at an early period, and not a vestige of it s to be found after the formation of the abdominal parietes. _ 2. Pic.—The placenta is formed by an expansion of the villous tubercles, as in {= chorion has not a body and two cornua, but is gg an elongated sac, whose : e are in relation with the adjacent foetuses. The inner face corresponds, ants, with the amnion and allantois. The latter is the same as in the Cow, it is very much shorter. The wmbilical vesicle, amnion, and cord are also the same as in Ruminants. __ 8. Carntvors.—The placenta is a thick cincture, surrounding the middle portion of the chorion. The latter resembles that of the Pig. The allantois is disposed, in principle, as in Solipeds. ; The umbilical vesicle, which remains very developed at all periods of foetal -life, resembles in shape the allantois of the Pig ; being a transversely elongated sac included between the amnion and the iuner allantoid lamina, and provided at its middle portion with a narrow pedicle, which is prolonged into the umbilical cord; its w are The amnion is lined, internally, by the inner lamina of the allantois. The wmbéilical cord has, as in ap an allantoid portion; but it is extremely short, and enveloped in a wide fold of the allantois, Resu_ts.—The comparative examination of the disposition of the placenta may furnish valuable indications as to the procedure to be adopted in practising artificial delivery ; as the surgical manceuvres should necessarily vary with the extent and disposi- tion of the * gpa of union existing between the uterus and the foetal envelopes. _ With this practical object in view, we believe that it is useful to divide the domesticated animals into two groups: those which have a simple, and those which have a oe pes Sout The first group may be subdivided, according as the simple general or - This division is summed up in the following table: 9 4 jn 4 7 : 2 General. . . . . Tae. Simple Placenta Local and Circular . { Bitch, Animals Multiple Placenta ove EMBRYOLOGY. COMPARISON OF THE ANNEXES OF THE HUMAN FORTUS WITH THOSE OF DIAGRAM OF AN EARLY HUMAN OVUM, SHOWING THE AMNION IN PROCESS OF PORMATION, AND THE ALLANTOIS BEGIN- NING TO APPEAR. a, Chorion ; 6, Vitelline mass, surrounded the blastodermic vesicle ; c, Embryo ; d, ¢, Z The wmbilical cord offers nothing particular. The at the termination of being from 6 to 8 inches. There is di the fetal placenta, in the midst cord arrives; and the maternal placenta, whose villosities dovetail Sp he ga 6 place towards the fundins of-Glin Maen ear ol ae cetenye en a resp num ae ‘ » . CHAPTER III. DEVELOPMENT OF THE FETUS. Is the two preceding chapters, we have seen how the fecundated ovulum is modified to furnish the earliest lineaments of the foetus and the organs annexed to it; this chapter will be devoted to an examination of the manner in which the foetus is developed. The young creature is designated an embryo during the early period of gp emgage has assumed any definite shape ; but as soon as it exhibits form of the species to which it belongs, it is named a satus, The transition between these two states, though they have different names, is altogether ccs ate pa so that we content ourselves with studying the first phases of development under the heading of the formation of the embryo, and the last under that of the development of the organs. Articte I.—Formation or tHe Empryo. When the embryo has assumed the form of an elongated streak, and shows in its middle the primitive groove, there appear in the middle lamina the blastoderm the p EP dorsalis, the vertebral lamine, and the lateral &, DEVELOPMENT OF THE CHORDA DORSALIS AND VERTEBRAL LAMINZE. The chorda dorsalis is a cylindrical cord, slightly attenuated at both extremities, which is developed beneath the primitive groove. On its sides is a series of small opaque quadrangular masses—the vertebral lamine—which are nothing more than the protovertebre, or first traces of the fetal vertebre. Each of these little masses is soon perforated by an ing, and is then divisible into three portions: the protovertebral cavity, — lamina, situated above the cavity, and the protovertebra, placed below it. The muscular lamine, in augmenting in volume, are inflected upwards, and unite in the middle line of the back, They form, in great part, the muscles of the vertebral furrows ; they also give off, below, prolongations which concur in the development of the intercostal and abdominal muscles, as well as those of the extremities. cod pepe curve upwards and downwards in such a fashion as to surround the protovertebral cavity or medullary canal, and the dorsal cord. The superior ring is the rudiment of the annular portion of the vertebra, and the inferior ring and dorsal cord constitute the vertebral bodies and the dises uniting them. DEVELOPMENT OF THE LATERAL AND CEPHALIC LAMINA. The lateral lamine is the name given to that part of the middle lamina of the blastoderm which is placed to the right and left of the vertebral lamin. Tn the region of the trunk, these lamine are separated for a certain period 906 EMBRYOLOGY, from the vertebral lamine; in the cephalic region they always remain adberent to them, and at this point they are named the cephalic lamine. 1. The proper lateral lamine are divided into two layers: an external and an internal, united by the middle lamina, and including between them a cavity which becomes that of the pleura and peritoneum—the Sent peritoneal cavity. It is after these primary modifications that the lateral lamine are fused to the vertebral laminew. The internal lamina, also named the fibro-intestinal lamina, envelops the — deep portion of the blastodermic layer or intestinal furrow, the umbilical vesicle, and the allantois. It constitutes the fibrous and vascular part of these membranes, and carries the vessels to the inner face of the chorion. The external or cutaneous lamina is developed in two directions. Above, it passes between the muscular laminew and the foetal portion of the external layer of the blastoderm, to form the skin of the back. Below, it separates into two other laminw, which receive between them the prolongations of the muscular lamine, destined to the formation of the intercostal and abdominal muscles and the ribs. Of these two secondary lamine, the external forms the skin of the trunk, and the internal the parietal layer of the peritoneum. The cutaneous lamin also have an extra-feetal prolongation—the fibrous layer of the amnion. : Fig. 433, THE EARLY STAGES OF THE DEVELOPMENT OF THE BODY OF A FOWL. A, The first rudiment of the embryo; a, Its cephalic, and }, its caudal end; c, The primitive groove-—B, The embryo further advanced; a, 6, c, As before; d, The dorsal lamin as yet developed only in the cephalic region, and not quite united in the middle line; e, The protovertebra.—c, The letters as before. The dorsal lamin have united throughout the greater part of the cephalic region, and are beginning to unite in the anterior spinal region.—p, Embryo further advanced, the dorsal lamine having united throughout nearly their whole length; the protovertebre have increased in number, and the omphalo-mesenteric veins, f, are visible, With regard to the middle or mesenteric lamine, they are confounded in the mesial line, and in their texture are developed the Wolffian bodies and the principal vessels of the trunk. THE FQTUS. ; 907 _ 2. The cephalic lamine always remain adherent to the vertebral lamina, and are inflected inwards with them to form the anterior portion of the cephalo-intestinal cavity. The latter is divided into two parts: the pharyn- geal and the esophageal cavities. The pharyngeal cavity opens externally by the mouth; it is partially closed, laterally, by the pharyngeal arches. The cesophageal cavity soon offers a diverticulum, which shortly after communicates with the pleuro- peritoneal cavity; this diverticulum lodges the heart, and is named the cardiac cavity. The cephalic laminew also form the derm of the cranium, and the fibrous layer in which some of the cranial bones are developed. Axticte II.—DrveLopMENtT oF THE VARIOUS ORGANS OF THE ANIMAL Economy. DEVELOPMENT OF THE NERVOUS SYSTEM. We will at first glance at the development of the nervous centres—the brain and spinal cord ; then their peripheral parts, the nerves. 1. Devetorpmenr or THE Brain.—We have seen in the preceding article how the primitive groove appears, and afterwards the medullary cavity. The latter, the first trace of the nervous centres, offers an en- largement at each of its extremities ; the posterior, or rhomboidal sinus, gives off the nerves of the sacro-lumbar plexus; the anterior gives rise to the brain. The latter enlargement is resolved into three successive dilatations—the cells or cerebral vesicles—distinguished as anterior, middle, and posterior. They are filled with fluid, and the middle slightly surmounts the other two, which gives the three together a triangular shape. The vesicles increase irregularly in volume ; their walls are gradually developed, and form the nervous tissue; while their cavity persists, and becomes the ventricles of each portion of the encephalon. Thus, the anterior vesicle represents the cerebral hemispheres, the thalami optici, and the lateral ventricles. The middle vesicle forms the cerebral crura, the corpora quadrigemina, and the aqueduct of Sylvius or middle ventricle. The posterior vesicle gives rise to the medulla oblongata, pons Varolii, and the fourth ventricle. The middle vesicle is that which, at first, increases most rapidly in volume; it soon, however, ceases, to allow the anterior cell to become developed, when the encephalon assumes its ovoid form, with a predominance of the anterior part. ' Towards the end of the first third of intra-uterine life, nearly all the of the brain are distinct: the two hemispheres have become isolable by the development of the septum lucidum; the convolutions appear on their surface ; the corpora quadrigemina and cerebral crura are distinctly defined. It is not until a little later that the cerebellum is distinguishable, as well as the pons Varolii, medulla oblongata, corpora restiformia, and corpora dalia. 2. Devetopment or THE Srrnat Corpv.—The medullary (spinal) canal is the first trace of the spinal cord; it occupies the whole length of the vertebral column, and its cavity communicates, in front, with the fourth ventricle. When the spine is developed, the marrow does not increase proportionately in quantity, and appears to ascend in the vertebral canal ; 908 EMBRYOLOGY. it stops about the middle of the sacrum in the equine foetus, but ascends higher in the other species. During this apparently ascensional movement is developed the filum terminale, and the nerves of the cauda equina. The walls of the medullary canal, at first very thin, increase in thickness by the appearance of the nervous matter of the cord. Soon they divide into two layers: an internal, the epithelium of the central canal; the other external, the grey substance of the cord, Gradually the canal contracts, and the marrow is seen, with its longitudinal furrows. At the end of the first month, the inferior roots are in existence, as well as the spinal ganglia ; the latter are developed at the expense of the proto- vertebrae, as will be shown presently. The superior roots are formed some time afterwards. The envelopes of the cerebro-spinal centres are furnished by the proto- vertebral laminw ; they are developed after the sixth week, progressing with the growth of the parts they are destined to cover. 3. DEVELOPMENT oF THE NERVES.— The development of the nerves is some- what obscure. The motor roots seem to arise from the cord; but the spinal gan- glia are formed separately in the pro- tovertebre, and perhaps originate the sensitive roots. The nervous ramifica- tions begin by elongated ramifying cells, which become fused to each other by their extremities ; the nuclei of the cells lying at the periphery becoming the nuclei of TRANSVERSE SECTION OF THE EMBRYO OF the white substance of Schwann, the A FOWL AT THE BEGINNING OF THE . Z THIRD DAY OF INCUBATION X 90-100. a echuslly aspectead Seal ney ch, Chorda dorsalis; wwh, Position of a lind d th 1 thinning, or cavity in the protoverte- CYy+nGer an © envelope. bral mass, dividing it into an anterior and posterior portion; Ap, Parietal lamina; df, Intestinal fibrous lamina ; dd, Intestinal glandular lamina; dr, Primitive intestinal groove; 4, Corneal lamina; mr, Medullary tube—spinal cord; m, Muscular lamina; p, Pleuro- peritoneal cavity; af, Fold of the amnion; ao, Primitive aorta; vc, Vena cardinalis; un, Wolfhan body; ung, Duct of the Wolffian body, The great sympathetic is early seen as a nodulated cord, It is probably de- veloped in the same manner as the other nerves. DEVELOPMENT OF THE ORGANS OF SENSE. The principal portion of the organs of sense belong to the dependencies of the nervous system, and are developed with it ; the other parts belong to the external epithelial lamina, the skin, and the germinative lamina. 1. Visuan Apparatus.—From the anterior cerebral vesicle are given off two tubular prolongations, which are directed forward, and terminate by the primitive eye-vesicles, traces of the ocular globes. The hollow protrusions form the optic nerves; the vesicles furnish the retina and choroid. The crystalline lens, vitreous humour, cornea, and sclerotica arise from the external blastodermic layer. These modifications take place in the follow- ing manner : The external integument of the foetus passes over the front of the primitive eye-vesicles. Here it shows a slight depression on its outer surface, and on its inner face a cellular protrusion (Fig. 435, 1, 0), which, becoming developed, surrounds the external depression, completely closes it, THE FOTUS. 909 and constitutes the commencement of the crystalline lens (Fig. 485, 2, 1). The latter, thus formed, presses on the backwards (2), and gives rise to a secondary ey becomes th therefore, a dependency of the epithelial lamina ; the cells com- ing it become elongated into in the centre, and are dis- posed at its circumference as a primary amorphous envelope— the crystalline capsule—and after- wards as a secondary envelope rich in vessels. The portion of the integu- ment which is not doubled to form the lens envelops the globe, and gives rise to the sclerotica and cornea; the epi- dermis furnishes the epithelium of the latter, which becomes distinct from the sclerotica in the course of the fourth month. An aperture—the sclerotic cleft—is made at the lower part of the fibrous envelope of the eye; this is connected with the development of the vitreous body : a prolongation of the derm—a kind of conjunctival bud passing primitive eye-vesicle, pushes it icle, whose anterior wall e retina, and the posterior wall the choroid. The lens is, Fig. 435. LONGITUDINAL SECTION OF THE EYE OF EMBRYO FOWL. 1, From an embryo at about the 65th hour of incu- bation; 2, From an embryo a few hours older; 3, From an embryo at the 4th day of incubation. —A, Corneal lamina; /, Lens in Fig. 1, still con- nected with the corneal lamina, and possessing a small cavity, 0, in its interior (in Figs 2 and 3 it is seen detached, but still hollow); r, Intro- verted portion of the primitive optic vesicle; sub- sequently becoming the retina; a, Posterior part of the optic vesicle, which, according to Remak, probably becomes the choroid coat, ciliary pro- cesses, and iris, and in Figs, 1 and 2 is still con- nected with the brain by the hollow optic nerve ; x, Thickening of the corneal lamina around the spot from which the lens has detached itself; g!, Vitreous body, or humour, through this opening, and placing itself between the crystalline lens and the anterior wall of the secondary eye-vesicle (3, gl), where it is developed and transformed into the vitreous body. At first it is encircled by vessels like the lens, but these disappear before the termination of gestation. The optic nerve is developed in the pedicle uniting the eye-vesicle to the anterior cerebral vesicle. The retina is formed by the inner lamina of the secondary eye-vesicle; it extends to the lens in changing its character anteriorly. According to Remak, the choroid is constituted by the posterior lamina of the eye-vesicle; it advances at first to the lens, and then becomes inflected in front to form the iris. The borders of the pupil are attached to the vascular envelope of the lens, and this gives rise to the pupillary diaphragm, which disappears before birth. The motor and protective organs of the eye are gradually developed around the globe. The eyelids are small cutaneous folds that appear towards the first third of uterine life; they increase, and unite at their — until immediately before, or soon after birth, when they separate. he lachrymal gland is a dependency of the epithelial lamina which is pushed in above the globe. At first solid, it gradually becomes channeled out by cavities, from which arise the excretory ducts. 2. Auprrory Apparatus.—The internal ear, auditory nerve, and middle ear, are developed separately. The labyrinth appears in the shape of a vesicle, which is not in direct relation with the posterior cerebral cell; it is constituted by a depression of the epidermic lamina, the auditory fossa, which 910 EMBRYOLOGY. is gradually developed, and at last become a closed cavity. At this time, the wall of the labyrinth is only a simple epithelial membrane ; this is soon covered, outwardly, by a vascular connective membrane that separates into - three layers: an internal, joined to the epithelium to form the membranous labyrinth ; an external, that lines the cartilaginous labyrinth; and a middle, whose soft, embryonic, connective tissue disappears, and is ‘replaced by the perilymph. At the same time that these changes of structure are occurring, the vesicular form of the labyrinth is modified, and shows the cochlea, semicircular canals, utriculus, and sacculus. The middle and external ear arise from the first pharyngeal (branchial) cleft, which is never completely closed, while the others disappear. At first, then, we find a cavity communicating externally with the pharynx; a ane. this cavity contracts, and is separated into ~ two portions by a partition that spreads € across its middle, and which becomes the a @ membrana tympani; the internal portion is: the middle ear and Eustachian tube; the ee portion is the exlernal auditory cana, The ossicula auditéis appear in a eartila- ginous state towards the third month; they gradually ossify, and have scarcely acquired their definitive volume at birth. The ex- ternal ear (concha) is developed above the integument after the second month. 3. Otractory Apparatus.—This com- mences by two depressions of the epidermie AN EMBRYO (HUMAN) OF FOUR ° : WEEKS, ENLARGED ABOUT THREE lamina, analogous to the auditory fossa and TTR, that of the lens. These two olfactory fosse a, Vesicle of corpora quadrigemina; ®ppear below the ocular vesicles, and become b, Vesicle of cerebral hemispheres; more and more distinct, being margined by c, Vesicle of third ventricle; 4, small projections which increase their depth. Vesicle for cerebellum and medulla . ° : oblongata; ¢, Auditory vesicle; /, Behind, they communicate with the Pp. Olfactory fossa; h, Liver; **, The appearance of the palate separates Caudal extremity. in front from the buccal cavity, and from this period the nasal fosse are constituted. They are completed by the development of the bones of the face. The olfactory bulbs and nerves are primarily hollow, and joined to the anterior cerebral cell. The nostrils are formed, in the young foetus, by a mass of mucus and epithelium; towards the middle of gestation they are open. 4. Gustatory Apparatus.—See, subsequently, the development of the tongue in digestive apparatus. 5. Taorirx Apparatus.—The skin and its dependencies—The skin is ‘developed at the expense of the epidermic lamina of the middle layer of the blastoderm. The cutaneous lamine, by the modification of their ele- ments, form the derma, in which the blood-vessels are very apparent at the third month. In the epidermis, the mucous and the horny layers are soon distinguished ; in the first, the pigment is visible at the commencement of the fifth month in the larger quadrupeds. When the foetus increases in volume, the epidermis exfoliates and its débris floats in the liquor amnii, In the third month, the hairs are seen in the foetus of the Mare and Cow; they appear at first on ‘the eyebrows, lips, and the joints of the limbs; at a ee 7 a el hal os) A ie THE FQ@TUS. 911 the sixth or seventh month they cover the body. They may be shed and renewed before birth. They are developed in a prolongation of the epi- dermic lamina, which is imbedded in the substance of the derm; it is shaped like a little bottle, and is composed of a mass of cells; in its centre, these cells are modified and collected together to form a small cone, whose base covers the growing papilla. This cone becomes elongated, touches the surface of the epidermis, doubles under the effort to push through it, and finally makes its exit, after which it can grow freely. The sebaceous and sudoriparous glands are developed in the same manner, towards the middle period of uterine existence. “The horny productions—the claws, hoofs, ergots, chesnuts—begin to show themselves early. Towards the end of the second month, in the feetus of the Cow, there is perceived, at the extremity of each limb, a small, pale, translucid, conical tubercle, which is the rudiment of the hoof. At the commencement of the fourth month, or thereabouts, the hoof, better defined, has become firm and opaque, and has assumed a fine yellow tint. At mid-term, brown or black patches are manifest if the coronet is provided with pigment ; it is only about the end of gestation that the hoof towards the coronet begins to have the greenish hue peculiar to horn destitute of pigment, but the remainder of this production, especially at the inferior part, preserves its yellow colour until birth. In Solipeds, the “ chesnuts” are shown at mid-term in the shape of thin brown plates, which are soon darker-coloured.”! The horn of the hoof is not at first tubular; after birth it is shed and is ogee by a more consistent tubular horn, which had been forming eath it. DEVELOPMENT OF THE LOCOMOTORY APPARATUS, 1. Tue SxeteTon.—We have seen at page 16 how the development and growth of the bones takes place; it is therefore needless to recur to this subject here; so we will limit ourselves to an examination of the mode of development of the principal sections of the skeleton. A. Devetorment or THE VertEBRAL Cotumn.—The vertebral column is the first portion of the skeleton manifested in the embryo; it is represented by the chorda dorsalis, a stalk constituted by a mass of cells situated in the interior of a transparent sheath. The protovertebre appear on each side of the chorda dorsalis; in becoming developed, these parts encircle the latter and the medullary canal; from this results the external theca of the cord, and the superior uniting membrane. From this time the vertebral column exists in the shape of a membranous axis. Soon this membranous spine is segmented to give rise to the vertebra, and its various portions gradually become cartilaginous. Each persistent vertebra docs not exactly correspond to a protovertebra; in reality, the latter takes a share in the formation of two vertebre, and divides into two portions: an inferior, which constitutes the posterior moiety of a permanent vertebra; and a superior, which forms the anterior moiety of the persistent yertebra immediately behind the preceding and the intervertebral disc, The bodies of the vertebrw are developed more rapidly than their spinal portion : thus, towards the end of the second month, all the vertebral bodies are already cartilaginous, while the vertebral lamine are yet membranous, * Colin. ‘Traité de Physiologie Comparée des Animaux.’ 2nd Edition, Paris, 1873. 912 EMBRYOLOGY. It is only in the third month that ossification begins in the vertebral column. The number of osseous nuclei, primary and complementary, is not the same in all species; they have been enumerated at page 20. In a large number, the spinous process is regarded as the result of the joining together of the two moieties of the vertebral arch; in the Sheep, on the contrary, the spinous process forms a nucleus altogether independent of the vertebral arches. Thomas has noted this disposition, and he considers it Fig. 438, DIAGRAM SHOWING THE POSITION OF THE DIAGRAM SHOWING THE ATTENUATION OF CHORDA DORSALIS IN THE BODY OF THE THE CHORDA DORSALIS ‘IN THE MIDDLE OF VERTEBRA, AND THE FORMATION OF THE THE BODIES OF THE VERTEBRA, WHILST NEURAL ARCHES. PRESERVING ITS ORIGINAL DIAMETER IN THE INTERVERTEBRAL SPACES. ch, Chorda dorsalis; v, Body of vertebra; c, Rib; pr, Transverse process. li, Intervertebral spaces, ch, Chorda dorsalis; cv, Body of the verte- as peculiar to animals whose anterior dorsal vertebre are furnished with a long spinous process. During ossification, the chorda dorsalis disappears, except between the vertebre, where it is developed to form the intervertebral substance or discs. B. DeveLopMent or THE CRANIUM AND Fcr.—The encephalon is en- veloped by a membrane formed at the expense of the protovertebral laminz. This cranial membrane becomes partly cartilaginous, partly fibrous; the cartilage exists at the base of the cranium, and seems to prolong the bodies of the vertebre into this region; indeed it is known that the skull may be resolved into four portions, each corresponding to a vertebra. The cartilage is insensibly transformed into bone; while the fibrous part, composing the roof of the skull and its lateral walls, passes directly into an osseous state. The bones of the face are developed at the expense of the pharyngeal arches. ‘This designation is given to four lamine (or lamelle) which spring from the anterior extremity of the chorda dorsalis, and double downward and inward to join those of the opposite side. They are also named the branchial and visceral arches, and the spaces between them are called the pharyngeal clefts. The upper jaw, mouth, nasal cavities: i.e. the nasal, maxillary, and palate bones, are furnished by the first arch. Meckel’s cartilage, which arises from the handle of the malleus to pass towards the inferior maxilla, is also a dependency of this branchial arch ; it disappears towards the sixth or seventh month. It is to be remarked that, at the commencement, the mouth com- municates with the nasal cavities; the palate is developed in two moieties bra; a, Neural arch, or neurapophysis ; THE FOTUS. 913 which advance towards each other, though they remain a long time apart ; so that at this time the young animal really has a hare-lip. The second Co arch forms the stapes, the pyramidal process of the temporal om. loid arch, and branch of the hyoid. The third develops the hyoid with its cornua; while the fourth arch only constitutes the soft parts of the neck. _ ©, Devetorpment or THE Txorax.—The ribs are de- pendencies of the proto- vertebral lamine, which curve towards the lower face of the vertebral column. The true ribs are most rapidly developed, and before attaining the middle line are united by their internal extremity, and form a moiety of the ster- A co Sig THE HEAD OF A FC@TAL LAMB DISSECTED TO SHOW : costal MECKEL’S CARTILAGE. right side from those of mum, The malleus; i, Incus; zy, The tympanic; u, The the left; this gradually hyoid; sg, The squamosal; pt, Pterygoid; p/, Palatine ; contracts, and finally dis- 1, Lachrymal; pm, Premaxilla; N, Nasal sac; Eu, appears, and the sternum Eustachian tube. is then formed. The ribs are, after the petrous bone, the parts of the skeleton which are most promptly ossified, ossification commencing in the middle ribs. The costal arches do not belong exclusively to the dorsal vertebree, but have a tendency to form along the whole length of the spine; and it is not rare to see, attached to the lumbar vertebra, a small cartilaginous nucleus which is soon lost in the texture of the abdominal walls. This nucleus assumes large dimensions on the last cervical vertebre of birds. _ ‘The form of the thorax varies with the species ; in some it is cireular, in others it is flattened laterally ; and in all cases it is less developed in the foetus and young avimal than in the adult. It is in the latter that the thoracic cavity presents, proportionately, its greatest dimensions. _ D. Deve torment or toe Lores.—The limbs do not show themselves until after the formation of the spinal column, the pharyngeal arches, and the thoracic parietes. They appear as four little prolongations from the thorax and pelvis, and are slightly enlarged at their origin and constricted _ in the middle. Their free extremity is flattened, and either divides or remains single, as the animal has one or more apparent digits. It is in . these prolongations that the cartilaginous rays are developed, which, at a later period, become the bones of the limbs. For the manner in which ossi- fication is carried on in each bone, reference must be made to Articles IV. and V., pages 71 and 91. 2. Musctrs.—The muscles are developed around the bones when these have become perfectly distinct. They may be divided into four groups: the vertebral muscles, which come from the muscular lamine of the protovertebre ; the visceral muscles—thoracic and abdominal cavities, neck and jaw—having 3.N 9lt EMBRYOLOGY, the same origin; the cutaneous muscles, which are develo of the cutaneous laminw of the middle layer of the muscles of the limbs, whose development is not yet perfectly known. ’ It was at one time believed that the muscular fibres were formed by the junction, end to end, of several elongated cells; but it is now known that they are constituted by a single cell which lengthens, and whose nuclei multiply and lie at the surface, while its contents are transformed into a 1 ae substance which offers the characteristics of contractile tissue. Fig. 440, DIAGRAM OF THE FORMATION OF THE VENA OMPHALO-MESENTERIC2 AND UMBILICALES, 1, At the time of the first appearance of the um- bilicales, and the commencement of the om- phalo-mesenterice ; 2, At the time of the first appearance of the branches to and from the liver, and the diminution of the omphalo- mesenteric vessels; 3, 4, At the period of com- plete foetal circulation in 1, Omphalo-mesenteric trunk; in 2, 3, Remains of it; in 4, Vein of the yolk sac alone;.om’, Right, and om”, Left vena omphalo-mesenterice; u, Trunk of the um- bilical vein; wu’, Right, and w”, Left vena um- bilicalis; de, Ductus Cuvieri; 7, Jugularis; c, Cardinalis; /, Liver; ia, hepatica advehentes ; hr, Hepatice revehentes; m, Mesenterice ; da, Ductus venosus Arantii; ci, Cava inferior; p, Vena porte; /, Lienalis; m, Mesenterica su- perior, The sar- colemma is formed after the fibre, by a modification of the con- nective tissue surrounding it. DEVELOPMENT OF THE CIRCULATORY APPARATUS, _ , During the first days which follow the appearance of the em- bryo in the substance of the blas- todermic layer, there is no trace of vessels in the area germinativa. It is not long, however, before the heart and some blood-vessels are seen in the middle layer, the vessels extending to the surface of the umbilical vesicle, which gradually shows itself. While the contents of the vitelline vesicle are being absorbed by the embryo, the heart is being completed, the vessels are developing, the allan- tois is formed, and the placental circulation, which continues until birth, is established. From this time the circulatory apparatus has acquired its definitive disposition. 1, APPEARANCE oF THE Hearv. —CrrovuLaTIon IN THE UMBILICAL Vestote.— The pleuro-peritoneal cavity of the embryo presents, anteriorly, a diverticulum, the car- diac cavity, in the interior of which the heart is developed. This organ appears at first as a small mass of cells, the innermost of which become separated from each other to create a cavity and con- stitute the blood-globules, As soon as it shows itself, the heart con- tracts and dilates alternately, the movements being very slow, though they gradually become quicker. Towards the twelfth day, the central organ of the circulation has the form of a contractile cylindrical tube. THE FQITUS. 915 From its anterior part spring two branches, the aortic arches (arcus aorte), which are directed towards the head of the embryo, and are afterwards in- flected downwards and backwards. They join together to constitute the single aorta, which, in its turn, divides into two trunks, the arterie vertebralis or rimitive aorte. 'These vessels pass along the lower surface of the embryo, pa to each other, and furnish during their course four or five divisions, omphalo-mesenteric arteries, which ramify in the area germinativa, and open into a limitary vein named the sinus (or vena) terminalis. From the _ network of the area and the sinus arise two vessels, the vene omphalo- mesenteric, which enter the posterior extremity ‘of the heart. The circulation in the umbilical vesicle is somewhat ephemeral in several species, and it has been already stated that the vesicle is atrophied at an early period of foetal life. In birds it is most extensive ; and its presence may be noted in the Carnivora during the whole term of uterine existence. PMENT OF THE HEART AND VESSELS.—PLACENTAL CIRCULATION.— The heart which, until now, was a cylindrical tube, is considerably modified before it attains its complete development. In its different phases, it successively offers all the forms known to exist in vertebrate animals. The first change consists in an inflexion; the tube curves in an § manner, so Fig. 441. . Fig. 442. HEART OF THE EMBRYO OF A THE SAME, SEEN FROM BEHIND. RABBIT, SEEN FROM BEFORE. a, Vene omphalo-mesenterice ; d, ta, Truneus arteriosus; /, Left ven- Right auricle; e, Bulbus aorte ; /, tricle; r, Right ventricle; a, Au- The six aortic arches; ¢, Atrium ; ricle; v, Venous sinus. b, Auricule. that its inferior part becomes superior; it then dilates at three points: the anterior and superior dilatation situated at the origin of the aorta is named the aortic bulb (bulbus aorte); the middle dilatation, the ventricular cavity ; and the posterior dilatation, the auricular cavity. Haller’s e is the name given to the constriction between the auricle and ventricle, which at this time are single. They do not remain long so, how- ever. The ventricular cay'ty is the first to be divided into two compart- ments, and the division is marked externally by a groove which appears on the surface of the heart of the Ovine embryo towards the nineteenth day, and on the twenty-fifth in the Equine foetus. This groove corresponds to an inter- ventricular septum which insensibly rises from the bottom of the ventricles ; when it reaches the auricles it concurs in forming the auriculo-ventricular i The margins of these openings are provided with a small slightly which afterwards, in developing, originates the mitral and tricuspid valves, e heart has now three cavities: two ventricles and an auricle ; but ina brief period the latter is doubled, and the compartments are then four in number. Externally, there is observed a depression which shows the ee 3.N openin salient lip, 916 EMBRYOLOGY. y in the auricles; at a point corresponding to it, a septum is developed in their interior which remains incomplete during the whole of foetal life, being perforated by the foramen of Fig. 443, Botal. With regard to the aortic bulb, it contracts and divides into two vessels, the aorta and pulmonary artery. wet RM oh Mig ‘- Ae (neat I Be cD partly at the expense of the é OTe vessels of the primary cireula- tion, and partly in the vascular lamina of the embryo. The heart, when it was only a simple cylindrical tube, presented at its anterior extremity two aortic arches, which curved backwards and united to form the single aorta, then the vertebral or common aorte. The aortic arches are situated at the inner face of the two first pharyngeal arches; afterwards more are developed, which are within the other pairs of arches, until the number is increased to five, though they never all exist at the same time. Some atrophy, HEART OF AN EQUINE FETUS, THE RIGHT AURICLE while othersare being developed : N RIOR VENA CAVA HAVE BEEN OPENED 5 abe oie FORAMEN OF BOTAL. the two first entirely disappear ; ; ‘ ; ; the third form the carotids: the 1, Left ventricle; 2, Right ventricle; 3, Interior of fourth th il d the right auricle; 4, Posterior vena cava; 5, Fora- 4° e axillary arteries an meen of Botal. the arch of the aorta; the fifth atrophies on the right, and on the left originates the pulmonary artery, the ductus arteriosus, and the aorta. The latter is continued along the spine by the fusion of the two primitive aorte ; they present, at their posterior extremity, the pelvic vessels, which are very small, and the umbilical arteries, which are, on the contrary, remarkable for their volume. The peripheral arteries arise, independently of the central vessels, on the interior of the vascular lamina, They appear in the form of solid cellular branches, which are hollowed in the centre by a cavity in which the cells become free. In proportion as these new vessels are developed, the omphalo- mesenteric vessels disappear, until at last there only remain one or two ducts that pass to the umbilical vesicle. The umbilical veins are developed immediately after the formation of the omphalo-mesenteric veins ; they enter the common trunk of the latter, and when its ramifications diminish in volume, the umbilical veins increase rapidly ; when the liver is formed around them, they throw into it branches, which are the rudiments of the hepatic network. Between the hepatic and subhepatic veins, the umbilical vein communicates with the vena cava by the ductus venosus of Aranzi, which, according to M. Colin, does not exist in the foetus of Solipeds in the last moiety of uterine life, The veins of the embryo form four principal trunks at first: two anterior, The arteries are developed | : | | THE FQTUS. " 917 the anterior cardinal veins ; and two posterior, the posterior cardinal veins. The yeiis of the same side unite in twos, from which result the Cuvierian ducts ; these open transversely into the omphalo-mesenteric trunk close to the auricular cavity. _ The anterior cardinal veins issue from the cranium; they form the jugular veins, and communicate by an anastomosis that extends transversely Fig. 444. PLAN OF THE AORTA AND ITS ARCHES AT AN EARLY PERIOD. 1, Truncus arteriosus, with one pair of aortic arches, and dotted lines indicating the position of the second and third pairs. 2, The same, with four pairs of aortic arches, and indications of the fifth. 3, The same, with the three posterior pairs of aortic arches, from which the permanent vessels of the embryo are developed, with dotted outlines showing the position of the two (now) obliterated anterior arches. 4, Permanent arterial trunks in their primitive form, the obliterated — still shown in dotted outline, 1-5, Primitive aortic arches.—a, Aorta; p, monary artery; p’, p”, Branchés to the lungs; aw’, Root of -thoracic aorta _ (ad) on lett side ; aw, Obliterated root springing from right side ; s”;-s’, Subclavian artery; v, Vertebral; ax, Axillary; c, Common carotid; c’, External carotid; ’ e”, Internal carotid. rs ot from left to right. Below this anastomosis, the left vein gradually atrophies, as does the Cuvierian duct of the same side; but the canal on the right side increases, and becomes the anterior vena cava. The posterior vena cava appears behind the liver towards the fifth month; it receives the veins of the kidneys and Wolffian bodies, and, behind, it anasto- moses with the cardinal veins. The latter disappear in their middle portion, and are replaced by the vertebral veins, the right of which forms the vena azygos. There only remain the two extremities of the cardinal veins; the anterior enters the Cuvierian duct, and the posterior constitutes the hypo- ) ic and crural veins. From this disposition, it will be seen that at first non system of the foetus is perfectly symmetrical, but that in the adult animal it becomes asymmetrical. In consequence of these successive developments, the placental circulation is instituted, and continues the same until the termination of intra-uterine life. The heart is always the organ that propels the blood, and this passes into the arteries, reaches the umbilical arteries, and is carried to the placenta. There it is renewed, becomes arterial through’ contact with the maternal blood, and is returned by the umbilical veins. In the substance of the liver it is mixed with the venous blood of the intestines and posterior extremities, through the medium of the ductus venosus, and at last arrives at the right auricle, then the right ventricle, from which it is propelled by a contraction. Instead of going to the lungs, which do not act as respiratory organs, the blood, being pressed by the contraction of the right ventricle, passes into the aorta 918 Fig. 445, DIAGRAM OF THE CIR- a, CULATION AT THE COMMENCEMENT OF THE FORMATION OF THE PLACENTA : SEEN FROM THE FRONT. Venous sinus re- ceiving all the sys- temic veins ; 6, Right auricle; 0’, Left auricle; c, Right ventricle ; c’, Left ventricle; d, Bulbus aorticus, subdividing into, ¢, e’, e”, Bran- chial branches ; /f, f’, Arterial trunks formed by their con- fluence; g, g’, Vena azygos superior; A, h', Confluence of the superior and inferior azygos; j, Vena cava inferior ; 4, 4’, Vena azygos inferior; m, Descending aorta; n, n, Umbilical arte- ries proceeding from it; 0, 0’, Umbilical veins; g, Omphalo- EMBRYOLOGY. br ene ductus arteriosus. To sum up, the foetus never a receives pure arterial blood into its organs, this being always mingled witl venous blood, the mixture ce place at several points: 1, By the foramen of Botal ; In the aorta by the ductus arteriosus; 3, In the liver by the ductus venosus. the posterior portion of the body of the foetus. At birth, the conditions of existence being suddenly changed, marked modifications take place in the- cir- culatory apparatus. The lungs become the organs of respiration, and rapidly increase in capacity; the pul- monary artery dilates to give passage to the blood that flows to them; while the ductus arteriosus is obliterated, in order to isolate the arterial from the venous blood. This separation of the two fluids also takes place in the liver by the atrophy of the ductus venosus, and in the heart by the occlusion of the foramen of Botal; according to M. Goubaux, that orifice frequently remaims open in young animals. Its persistence has also been noted in the human adult. Notwithstanding the pre- sence of this foramen, the circulation cannot be much disturbed; as when the heart contracts, the auricles — become isolated by the constricting of the orifice and the raising of a valve. DEVELOPMENT OF THE RESPIRATORY APPARATUS, Observers are not unanimous as to the deyelop- ment of the lungs. According to Reichert and Bischoff, they arise from two small solid cellular masses lying on the surface of the anterior portion of the intestinal canal, These become channeled out into numerous ramifying cavities (by the deliquescence or fusion of the internal cells), which communicate with the trachea. Costa states that they commence by a median, bud-like, hollow process that opens into the cesophagus. The walls of the communicating aperture elongate consider- ably, and at a later period form the trachea and larynx; while the hollow bud divides into two pyriform sacs, each of which becomes broken up into a multitude of subdivisions to constitute the pulmonary lobes, with their vesicles and infundibula. The trachea is completed by the development of the cartilaginous rings in the tube that binds the lungs to the esophagus. They appear at the commencement of the third month. The larynx is developed in the same manner at the pharyngeal opening; it is always somewhat undefined mesenteric vein; 7, Omphalo-mesenteric artery distributed on the walls of the vitelline vesicle, ¢; r, Ductus venosus; y, Vitelline duct; z, Chorion, The head and neck are the. parts which receive the purest arterial blood, a fact which explains the predominance of the anterior over. THE FQTUS. 919 during youth, and its definitive volume is not acquired until the period of The thymus gland appears asa process of the respiratory mucous mem- brane; it seems to be formed at the larynx, and gradually descends along Fig. 446, the trachea to the entrance of the thorax. DEVELOPMENT OF THE DIGESTIVE — APPARATUS. In this paragraph, the develop- a ‘ ment of the alimentary canal will be ho first studied, then that of the organs FIRST APPEARANCE OF THE LUNGS; annexed to it. a, In a Fowl at four days; 6, At six days;.c, A. Auimentary Canat.—We have Termination of bronchus in a very young seen how the embryo, in becoming 8: ; incuryated, divides the blastodermic vesicle into two parts which com- municate by a large pedicle. The external portion is the umbilical vesicle ; the pedicle is the omphalo-mesenteric duct, and the inner part the intestinal cavity. The latter may be decomposed into three portions: the anterior intestine, Fig. 447. EMBRYO OF DOG, TWENTY-FIVE DAYS AFTER LAST COPULATION, a, a, Nostrils; 6, b, Eyes; ¢, c, First visceral arches, forming the lower jaw; d, d, Second visceral arches; e, Right auricle; /, Left auricle; g, Right ventricle; A, Left ventricle; i, Aortic bulb; 4, 4, Liver, between the two lobes of which is seen the divided orifice of the omphalo-mesenteric vein; /, Stomach ; m, Intestine, communicating with the umbilical vesicle, n, n; 0, 0, Corpora Wolffiana; p, Al- lantois; q, g, Anterior extremities; r, r, Posterior extremities. which forms the pharynx and wsophagus; the posterior intestine, that gives rise to the rectum; and the middle intestine, which becomes the stomach and intestines. 920 «. (BRYOLOGY. ‘The middle intestine appears at first as a uniform cylindrical tube, whose diameter is afterwards modified the cesophagus and rectum. 1. Mouth—It begins by a depression limited by the maxillary buds; this blind pouch gradually enlarges inwardly, and proceeds to meet the pharynx, from which it is only separated, at a certain period, by a thin membrane ; this is at last absorbed, and the two cavities then communicate, Until the third month, the mouth is confounded with the nasal cavities; at this time the palate appears, and eventually isolates them. 2. Tongue.—Appearing at first as a small prominence from the buds, the tongue is completed by the addition to it of a bud from the second branchial arch. Its epithelium and glands come from the external blas- todermic lamina; they are developed in the third and fourth months. ; 3. Pharynx and Gisophagus.—These two organs become enlarged and elongated as the foetus grows. The esophagus communicates at first with the trachea ; but it slowly closes, and finally separates completely from that canal. 4. Stomach.—Th's is formed by the dilatation of the anterior part of the middle intestine; this dilatation is fusiform, and its largest axis lon- gitudinal ; it soon incurvates, and its longest axis is then transversal. In Ruminants, the stomach is at its first appearance simple; but before long it shows grooves on its surface, and in its interior septa, as in the normal state. During foetal life this organ is small; but after birth, when solid food begins to be taken, it augments rapidly in volume. During lactation in Ruminants, there is remarked a predominance of the fourth over the other gastric compartments ; but immediately the young animal commences to consume fibrous aliment, the rumen quickly increases in size, and it is not long before it becomes the most considerable division. 5. Intestines—The intestinal tube is primarily of a uniform calibre, - though in a short time there can be distinguished the various regions of which it is composed. According to A. Baer, the cecum is early seen in hoofed animals,/and is situated in the vicinity of the omphalo-mesenteric duct. This duct detaches itself from the extremity of an intestinal loop, which is drawn towards the umbilical ring; when the latter is becoming atrophied and progressing towards complete obliteration, this loop re-ascends into the abdominal cavity. The intestines are smooth on their inner face during the first two months ; but during the third they show their villosities and the glands of Lieberkiihn. The Brunnerian and solitary glands are a little later in showing themselves. 6. Rectum.—This is derived from the posterior intestine, and is de- veloped like the other portions. 7. Anus.—Towards the caudal extremity of the foetus is observed a depression analogous to the buccal cul-de-sac. This gradually deepens, and is joined to the rectum and genito-urinary organs. Later, it is separated from the latter, and then belongs exclusively to the alimentary canal. B. Annexes or Tan Atimuntary Canat.—These are the salivary glands, teeth, liver, pancreas, and spleen. 1. Salivary glands.—These are developed in a solid cellular bud, which is related to the epithelium.at the commencement of the digestive apparatus, This bud increases, and at the same time is hollowed into glandular pouches. The submaxillary gland is the first to appear; according to Bischoff, it is entirely formed in the foetus of a Cow only an inch in length. The parotid gland is the last to be formed. to constitute the organs comprised between — THE FQ@TUS. 921 _ 2. Teeth—These organs are developed in the interior of a cavity, named the dental follicle or sac, by means of the elements of three germs: one belonging to the ivory, another to the enamel, and a third to the cementum. _ Follicle-—The dental follicle is an oval cavity with walls composed of two layers: the external is fibrous and complete; the internal, soft or gelatinous, is allied at the bottom to the ivory germ. The latter is a prominence which is detached from the bottom of the follicle, and has the exact shape of the tooth. Its structure comprises, in the centre, delicate connective tissue provided with vessels and nerves, and on the surface a layer of elongated cells. At the summit of the follicle, facing the ivory is the enamel germ ; it is exactly applied to the dental pulp which it invests like a cap, and is composed of a small mass of mucous connective tissue covered by a layer of cylindrical cells, joined to the buccal epithelium by the gubernaculum dentis. The cementum organ manifestly exists in the according to M. Magitot. The base of the ivory germ has been found, but it disappears rapidly after having performed its function. How are the different parts of the dental follicle developed? On the free borders of the maxille the epithelium of the buccal mucous membrane forms an elongated eminence—the dental ridge. Below this ridge, the epithelium constitutes a bud which develops in size, and is sunk in the mucous membrane: this is the enamel germ; it has a layer of cylindrical cells on its deep surface, and in its centre are round cells. After a certain time, it is only joined to the epithelium by a very thin line of cells—the um dentis. While this enamel germ grows downwards, it covers, by its base, a connective bud which rises from the mucous derma. The two buds are reciprocally adapted to each other, and around them the connective tissue condenses, and gives rise to the walls of the follicle. It will therefore be seen, that the enamel organ is a dependency of the epithelium, and the ivory organ a production of the mucous derma. Formation of the ivory, enamel, and cementum.—The ivory and enamel are developed by the modification of the elements situated at the surface of their germ. It has been shown that the germ of the ivory, or dental pulp, had exactly the form of the future tooth; consequently the ivory which arises from its periphery offers the shape of this tooth. The ivory (dentine) is constituted by the cells of the germ, which elongate, send out prolongations —the dental fibres—that ramify and anastomose, and by an intercellular substance which is impregnated with calcareous matter, is moulded around these fibres, and forms the dental canaliculi. The enamel is derived from the deep cells of its germ, which are elongated and prism-shaped, and are calcified in becoming applied to the surface of the ivory. The cementum is developed at the expense of the walls of the follicle, according to the mode of ossification of the connective tissue. Eruption.—As the ivory is formed, the tooth increases in length and the enamel germ upwards; the latter, constantly compressed, becomes atrophied, and finally disappears when the tooth has reached the summit of the follicle. In the same way the young organ pierces the dental follicle and gum, and makes its eruption externally. Such is the mode of development of the eaducous teeth, and the per- manent ones are formed in the same manner. There is seen, during the development of the enamel germ of the temporary tooth, a bud detaching ' 922 EMBRYJ/ LOGY, itself from this germ, and passing backward to serve, at a later period, in forming the persistent tooth. 3. The liver—This gland commences to be developed very early in all the species. It appears on the surface of the duodenum in the form of two or more buds, according to the number of lobules in the adult liver. To tf these external buds are correspond- Fig. 448. ing internal ones, arising from the intestinal epithelium. The first — enlarge and envelope the omphalo- mesenteric vein; the second ramify in their interior, and form the system of biliary canals. The liver grows rapidly, and, towards the third month, almost entirely fills the abdominal cavity ; at a later period its growth is less ORIGIN OF THE LIVER FROM THE rvrestrvan Marked, although at birth it is yet WALL IN THE EMBRYO OF THE FOWL, ON THE proportionally larger than in adult FOURTH DAY OF INCUBATION, i e. a, Heart; , Intestine ; c, Everted portion, giving 4, Pancreas.—The pancreas origin to liver; d, Liver; e, Portion of vitel- * * line vesicle. first “F pats like the salivary glands, in the form of a solid cellular bud, which afterwards is channeled into ramescent cavities. 5. Spleen.—According to Bischoff, this body is developed, during the second month, on the large curvature of the stomach. Arnold states that it is formed at the same time as the liver, in a strip extending from the stomach to the duodenum, It subsequently separates from the pancreas and becomes fixed to the stomach, where its elements Fig. 449. ~— assume the character of spleen tissue. DEVELOPMENT OF THE GENITO-URINARY APPARATUS, The development of the genital is related to that of the urinary organs, as the apparatus they form have some parts in common, Immediately after the formation of the intes- tines, the genito-urinary organs are supplied by the Wolffian bodies. These, also named the primordial kidneys and bodies of Oken, are glandular in structure, and extend in front of the vertebral column from the heart to the pelvis. They are composed of small transverse canals, filled with a whitish fluid, which enter a common excretory duct that lies parallel to the spine, and opens inferiorly into that portion of STATE OF THE GENITO- the allantois that becomes the bladder. The Wolf- URINARY APPARATUS IN fian bodies are placed behind the peritoneum, and THE EARLY EMBRYO OF are attached by two serous folds: an anterior, the ‘ xg. eis Giana: bp, aphragmatic ligament, and a posterior, the lwmbar ’Thelr excretory ducts; Ligament of the corpora Wolfiana. ‘The organs furnish c, Kidneys; d, Ureter; @ liquid analogous to the urine; though it is not 2, @, Testes. long before their secretion undergoes great modi- fications ; indeed, these bodies soon atrophy, and dis- appear more or less rapidly, according to species, One portion serves for CO 2. THE FQTUS. 923 the development of the genital organs; the other gives rise to organs whose signification is unknown—such as the organ of Rosenmiiller, which is very a in the Mare, and the canals of Gaertner, visible in the Cow (Mare, A. Unwyary Oraans.—We have seen above how the allantois is derived from the terminal portion of the intestine; it has now to be stated that the bladder is derived from the allantois. This reservoir is the result of the dilatation of the abdominal portion of the allantois. During foetal life, the bladder is extended by the urachus to the umbilical ring; but after birth the urachus is obliterated, and the bladder is withdrawn into the pelvic cavity. Hereafter we shall study the urethra. The kidneys appear a long time after the Wolffian bodies, in the shape of two blind pouches constituted by a pushing back of the upper wall of the small vesicle of the allantois. These little culs-de-sac ramify, and are afterwards replaced by solid buds, in whose interior are developed the uriniferous canals and Malpighian bodies. According to certain observers, the kidneys subsequently communicate with the ureters, which are developed separately in the middle layer of the blastoderm. In the female, the Wolffian bodies do not entirely disappear; the of Gaertner and the bodies of Rosenmiiller, situated in the broad ligaments, between the ovaries and Fallopian tubes, are their remains in adult life; traces of them are also found in the male, near the head of the epididymis, where they id the vas aberrans of the testicles. The suprarenal capsules are very large in the Equine fetus, being nearly one half the size of the kidneys. ; B. Genrrat Oreans.—The genital apparatus of the male and female are at first very much alike ; indeed, during a certain period it is impossible to distinguish the sexes; so that some authorities have proposed to term this period the “indifferent state of the genital organs,” Later, the sexes are defined ; and this period of development may be studied in the internal and external organs, 1. Indifferent state of the internal genital organs.—Towards the sixth week, there is observed on the lower face, and near the inner border of the Wolffian bodies, a little white cord, which increases in volume and maintains almost the same position. This is the genital gland, which is attached to the Wolffian body by serous folds, and is formed by a mass of young cells sustained by an enveloping membrane. The development of this gland is accompanied by the formation of the genital or Miiller’s duct, which is seen to the inside, and in front of, the Wolffian duct. Miiller’s duct is at first a solid cellular column, which afterwards becomes a canal; it terminates above in a blind pouch, and opens, below, into the bladder, near the Wolffian duct. Development of the internal genital organs of the male.—These result from modifications of the genital gland and Miiller’s duct. The testicle arises from the gland, which shortens and widens a little, while its tissue is transformed into seminiferous canaliculi. The head (globus major) of the epididymis is formed by the middle portion of the Wolffian body; the tail (or globus minor), vas deferens, and ejaculatory duct, are derived from the olffian duct. Lastly, the vesicule seminales and the origin of the urethra are formed by the posterior extremity of Miiller’s ducts, which join and open into the uro-genital sinus, as the very short canal is named which communicates between the bladder and cloaca, The developed testicle remains in the abdominal cavity, or descends through the inguinal canal . ~ Seth = 924 EMBRYOLOGY. into the scrotum, The mechan yn of this descent has been already — explained. ; (It may be only necessary here to state, that in the Equine species the testicles do not usually descend into the scrotum until some time after birth—about six months; while in other animals they reach that sac during foetal life. In the Bovine species, the testes are in the scrotum about the twentieth week of gestation, and in the Sheep and Goat about the fifteenth week; indeed, it has been observed that in all Ruminants their descent is — effected before the skin is covered with hair. In the Carnivora, they are usually in the scrotum a few days before birth.) Development of the internal genital organs of the female.—The ovary is derived from the genital gland, whose anatomical elements are so di as to form the stroma, Graafian follicles, and ovules. The Fallopian tube and its pavilion are formed by the anterior part of Miiller’s duct, whose extremity shows a small linear orifice. The uterus and vagina arise from the posterior part of Miiller’s ducts. These lie beside each other, and end by joining behind to constitute a single canal; this fusion giving origi to the body of the uterus and the vagina. ie we The two diverging portions of the ducts comprised between the point of junction and the Fallopian tubes, compose the cornua of the uterus. The uterus and vagina are at first placed end to end, without any apparent separation; but towards the sixth month the neck of the uterus commences to be defined. 2. Indifferent state of the external genital organs.—The intestine is terminated by the cloaca, a cavity into which the digestive canal and bladder open by the uro-genital sinus. This confusion quickly ceases by the development of a transverse septum that divides the cloaca into two compartments: the anal opening, and the uro-genital canal. At the inferior end of the latter appears the genital tubercle, a rudiment of the penis or clitoris, and which is surrounded by cutaneous folds—the genital folds. This tubercle increases in volume, and has a furrow passing from behind to before. Up to this moment it is impossible to distinguish the sexes, : Development of the external genital organs of the male-—The male sex is marked by the rapid development of the genital tubercle, which becomes the penis, the extremity of which enlarges to constitute the glans. The genital furrow closes posteriorly, and forms the urethra. The folds draw round to each other below the penis, unite in the middle line, and thus produce the scrotum. Owing to these modifications, the digestive ap- — paratus is completely separated from the genito-urinary organs, and the urethral canal is connected with the bladder and the excretory ducts of the testicle. Development of the external genital organs of the female-—The indifferent state of the genital organs is readily succeeded by the feminine type. The uro-genital sinus forms the vulvular cavity or vestibulum of the vagi which is so marked in the lower animals. The genital tubercle becomes the clitoris; the genital furrow closes at a certain part to constitute the perineum; while the genital folds form the labia of the vulva. The mamme, dependencies of the generative organs, appear after the first month of uterine life. ' ' 4 q “4 | [ 925°] CHAPTER IV. THE OVA OF BIRDS. Ir has been stated, with regard to the ovaries of birds, that the ovules “pained nearly the naga mass of these organs. When it leaves the ovary, ovum presents the same parts as that of mammals, only differing in volume, which is enormous in birds. It is in passing through the oviduct that it is covered with a thick layer of albumen and enveloped in a white membrane, and then a shell, to compose what is usually known as an egg. It is therefore composed of the ovulum and accessory parts (Fig. 450). Ovutum.—There is found in the ovulum: 1, A vitelline membrane (2), thinner, proportionately, than that of mammals; it is fibrous, and shows on acertain point of its surface: 2. The cicatricula (8), a yellowish-white disc, in the centre of which exists, 3, Purkinje’s vesicle, or the germinal vesicle ; the yolk or vitellus (1), which fills the enveloping membrane. In the mass of the Sree is on pone to = a bottle-shaped cavity, the long neck of ich is applied to the cicatricula. The — of the eee of birds differs from that of mammals in its anatomical composition, being entirely composed of what are designated _vitelline globules. These globules are white in the centre of the egg, and have only a few nuclei; in the re- mainder of the mass they are much more voluminous, and contain a large number of granulations which give them their yellow colour. It is the of the clear vitelline Berger oe cee the genic SECTIONAL VIEW OF FOWL’S EGG of rs a which art ies 1, Yellow yolk composed of successive layers; 2, Fise Se SSERUEO © “ Vitelline membrane; 3, Layers of albumen; 4, bottle-shaped figure, named Two principal layers of the lining membrane of the latebra (9) by Purkinje, is the shell ; 5, Calcareous shell; 6, Chalaze ; 7, Air- a cavity. space between the two layers of the shell; 8, Accessory Parts.—These i4tricula, with its nucleus, beneath which is comprise : 1. the while. oe seen the canal leading down to the white yolk ‘Aliumen (8), disposed in three ™™ ®- layers of different densities, and which are deposited around the yolk at three different periods during its course along the oviduct; 2, The chalaze (6), species of albuminous ligaments twisted in a spiral manner, and attaching the yolk to the testaceous membrane; 3, The testaceous or shell-membrane (4), which offers towards the obtuse pole a doubling into two layers, between which are found: 4, The air-chamber (7), so named from the air it contains ; 5, The shell (5), decomposable into several layers. The testaceous or shell membrane is composed of a closely woven fibroid tissue ; it owes its opacity to the air it contains in its meshes. 926 EF ¥BRYOLOG ¥, The shell is very solid, and impregnated with calcareous salts; it is 4 perforated by a multitude of cavities opening on its surface. ‘When closely examined, it is found to have a more or less shining aspect, and in its mass fine sand-like particles. Landois, who has completed the researches of Wittich on the ovum of birds, distinguishes several layers in the shell; otherwise their number varies with the species. The shell, acting merely as a protecting canes is all the more solid and complicated as the eggs are more exposed to the inclemency of the weather. Independently of the testaceous membrane which Landois attaches to the shell as a fibrous layer, this authority also recognises the uterine gland layer and the spongy layer. The former is much impregnated with ecal- careous salts, and deeply studded with little round bodies which are the remains of the uterine glands, and give to the shell its sandy appearance. The spongy layer is structureless, and analogous to solidified mucus. This description demonstrates that the ovum of birds is distinguished by | the considerable volume of its vitellus, and the addition to it of those accessory parts which give the egg its large dimensions and yet These differences will readily be understood, when it is remembered that embryo must find in it all the materials necessary for its development, which takes place external to the parent. It is from the vitellus and the albumen that the young creature derives the elements which the mammal finds in the uterine mucous membrane to which it is fixed. 4 627 "897 _— traneverse communicating pee” —-ofnerves . . es ae PAGE Anatomical elements . . . . . 3 Oe ah a mh ce SS Ba As 1 ——comparative . . . ». + « definition of . . , 5 ae —— descriptive ; ages pare RONBTEE 6 6) Ss ia ee a ni ——philosophical . . . . . . & —physiological . . . . . «. ———regional . . . 4 we ry —e special . . . —surgical . . .- ib —— topographical . ib, —— transcendental w. Se ot ce ee: Ancyroid cavity Salsa te Maveuse © 55)! SINE Andersch’s ganglion . 727 Aneurism . Sy Aa Lute hos eet 3 EE PDGIGIORY ee ns a ey SO Auiuavamidon, 2-5. Se ee ARB —— protuberance. . . . . . 675 Annotes albidgs".* => os - |, 3 ee ovalis . . ee pee ee ee Anomalies in arteries. 5 Sees Anorchidism . ae coe Ansiform tube of Henle ei eh Anterior antibrachial dey ane tot), oe —aorta . . Coton fa, ee — Sindiallcs 02 oe ) eae ty ee ——cruralregion , . . . . . 283 — mediastinum . . ¢ Sites ae —— peduncles of conarium Patel hin Pee, —— tibial region . I —— white commissure of brain tive. OSes Anus rae tals, Samy Fle —-- development of ees . 920 Aorta. 3 “Carat sete —_—_ anterior =) pl on a ol ee ——common . SE eee ——— comparison pitcgaephr ey peed? —-——ofanterior . . . . . 559 —— differential characters in. . . 535 ~ ——carnivora, . . . 537 a eee eee pig . . . ib. ——— ruminants .. . 535 —— parietal branchesof . . . . 525 ——— posterior © « : i. sw O88 ——preparationof . .. . . 524 Aorta, visceral branches of Aorte, primitive Aortic heart Aponeurosis . antibrachial —— contentive Apparatus in birds —— digestive, in mammalia in birds . generative innervation, of —— olfactory in birds sense, of — smell, of —— taste, of touch, of . — urinary —— vision, of . . Appendix auricularis . Aqueduct of Fallopius . of Sylvius . Aqueous humour — membrane of Arachnoid membrane cranial spinal . . structure ventricular . Arantius, nodule of Aranzi, duct of . . Arbor vite cerebelli . Arciform fibres of bulb . Arch of aorta hemal . —— ischial . ischiatic neural. . pharyngeal Arcus aorte. . Area germinativa pellucida . Arm, bonesof . . Arms of pelvis of kidney Arnold’s ganglion ; . Arterial zones of heart . Arteria helicine . . —— vertebralis Arteries . y — anastomoses of anomalies, — course circulatory, i in mammalia_ respiratory, in mammalia 792, 815, ieee: PAGE 2 . 526 | Arteries, direction . . . ry . 915 Seneaaee, . . . 506 ae form . . . . . . 179 —— general considerations . . . 261 es form . . . ’ . 183 —— injection. . . 2 ae . 241 —— mode of distribution, Fs ipo . ib. waneces) of origin . . . * . 284 —— preparation . . . . . . 280 a relations . . . . . . . 863 —— structure. :, TR: — termination . . .. . aay =e — vessels and nerves . . . 5 268,308 | —— abdominal, anterior . . . . 5 = . 297 ey Sain posterior . . . . oo ; 5|;— subcutaneous . . . . 8 ; 498 accessory thyroid, . . 647 anterior dorsal of ga oe a ee tibial. > ee 485 |.—— sternal” 5. >, 1° a ; 851 | -— atloido-muscular . es | 650 | —— auricular, anterior... a: x 815 | ———— posterior . . . . . ws 439 | ——axillary . . . . . . . BOD 475 | ——-——-ollaterals . . . .. — | —— ——-comparisonof . . . . 815 | ———— differential charactersin . re. 813 | ——pbasilar. . . . ... » His | 792 | —— brachial Br las - poen 4 484 | —— bronchial ae - 526 816 | —— broncho-esophageal . ike | . 503 | ——bu ame » oD . 842 | —— bulb ._ ao 682, 683 | —— cecal . j . 581 | 827 | —— cardiac - 528 a= ib. ba left . . . . ib, : 663 | ——+— right |. 664 | ——carotid,common . . oie | 663 | —— —— collateral branches. ma » ib. | ——-——— comparison of . . . . 579 \ 694 | —— ——- differential characters i me 505 | —— external, 5° < l= eee 901,916 | ——-——internal. 2. 2. 5 5 yy 688 | —— —— primitive Mg an 685 | ——centralis retine . -- » OSB 523 | ——vcerebellar, anterior . . . . 119 | —— posterior ie a ee 96 | — cerebral, anterior . ib, | —— middle .; 119 | —— —— posterior 912 | —— cerebro-spinal P 915 | —— cervical, deep 892 | ——- —— inferior ; ib, | ———- —— superior F 73 | —— cervico-muscular : 486 | —— transverse 720 cil : " . 508 | — circumflex, of coronary cushion - 865 | ——-—— anterior, of shoulder 915 | —— —— posterior, of shoulder 515 | —-—— or, of foot... 517 | —— circumflex iliac . 520 | —— coccygeal, lateral. . 516 | ———— middle , Mos ps — if ln a as | ae x » er vi INDEX. far © PAGE RS See 527 | Arteries, interosseous anterior. . colic, direct or right . 531 | —— —— metacarpal . Pa left or retrograde ih, | ——-—— posterior . . . of the cannon 551,569 | —— intestinal, small . . . . branches... 569 | —— ischiatic oF coll the digit 552 | —— labial, inferior Ss shatesl — sreat posterior of thigh -__ = gee il q —— to ae) 8 é a2, oT —— —_ collateral branches = Og Faker ; e : — — — erential characters in, 543 ——iliaco-eacal . . ae eaistemier . . ..< 6k —— inferior circumflex of foot ae — ——- communicating ,, . -——_ ——- vesical . . . ——innominata . —— innominate branches of gent me- re ° ——intercostal . . .. =. ——internal pudie .. — — — of female . — — — of male —— interosseous, of fore-arm . 546 531 —— —— superior . ~— laminal, anterior. . . —— lateral sacral . — collateral branches —- — middle . —- — - —— terminal branches —— lingual —— lumbar ——mammary. . — — external . —— —— internal . ——masseteric. . . — mastoid —— maxillary, external — — in — maxillo-muscular -. —— median-spinal. . — meningeal, great . ie —— mesenteric, great. . . .« anastomoses anterior. . of left fasciculus: . . of right fasciculus ————— —— —— —— innominate branches . ——small ... —— metatarso-pedal —— muscular, deep — —— great anterior —- — superficial — nasal é _ obturator : — occipital . : —— —— collateral branches . —— occipito-muscular ophthalmic ——palato-labial . 2. . ~—— popliteal. ; —— posterior auricular — — communicating . —— —— dorsal of penis . — — tibial ——— —— — collateral branches 80 sack > 930 : PAGE Arteries, pen tibial terminal branches 1b. —— prehu 565 preplantar ungueal 554 prepubic 547 —— prevertebral . . 577 —— profunda femoris . 548 —— pterygoid . 587 —— pulmo : 52L — —— preparation of . ib. — pyloric. . . 0... 528 —— radial, anterior 566 —— —— posterior 567 renal... 534 —— retrograde. 577 — sacral, lateral . 540 sacra media 526 —— saphena 549 scapulo-humeral 564 —— small testicular 535 —— spermatic . 534 —— spheno-palatine 589 — spinous . 587 —— staphylin . 589 — subcostal . 561 —— sublingual . 584 —— subsacral . 540 —— subscapular 564 subzygomatic . 586 —— superficial temporal 585 superscapular . 564 ——— supra-orbital . 588 —temporal . . 585 —— —— deep anterior 588 —_— posterior . 587 terminalis, . . 915 — testicular, great . 534 — ——small . 535 —— thoracic, anterior . 563 — —— external ab. —— —— inferior . —— — internal. . . ag —_. —— ——terminal branches. $ &b. —— thyro-laryngeal . 576 —— trachelo-muscular 564 —— transverse-cervical 560 —— tranverse of face . 586 —— tympanic . 587 ulnar. , 566 —— umbilical . 538 —— uterine. 535 —— utero-ovarian . ib, —— vasa brevia : 528 -_— intestini tenuis . 529 vertebral . ; 561 vertebralis . . 915 ——— vesico-prostatic 40, 861 Arthrodia ; ~ 128 Arthrology . . 123 Articular cartilages . ab, surfaces, 121 Articulations . ib, in general ib, —— in particular 129 —— nomenclature 128 Articulations, anterior limbs, of —— —— transverse vertebral COX®@: 5. coxo-femoral wits — elbow . ‘or. femoro-tibial . . —head .. — humero-radial —— hyoideal F —— interchrondral —— interhyoideal . —— intermetacarpal interphalangeal . . first’. “cS —— —— second : —— —— third intertarsal intervertebral ischio-pubic : laryngeal cartilages, of —— metacarpo-phalangeal —— occipito-atloid 3 — pelvic. . -——. posterior limbs —— radio-carpal — — ulnar —sacro-iliae. . . — pr Sing ia * 4 — tarsal . $ — tarso-metatarsal — temporo-maxillary — — hyoideal thoracic . —— tibio-fibular tarsal. Arytenoid cartilages Auditive scala = Auditory mai tiies Auricles ... : Auricular facet... mass. Auriculo-ventricular opening sones. Axile bodies. . . « . Axillary region. . . Axis, celiac . oie Mite — cylinder — — of arteries Baccated fibres of tooth Bacilla: ary layer of retina Balbiani’s vesicle Band of Reil ‘ Barbs : Bars of hoof. Wes Bartholine, glands of. ; ‘Cais J Vir’. OL. Cae oe te te ee ee gow R> &h. Sede Oo of te ea Se Se eG Ore. 2 ieee . oie - : i ee) ee | a. | . be al ae. | : 26 a « 140 8 AS 3 140,142 So 505, vy Syn 92 ~~ : eS - Eas . 794 - . 231 . BIS . 825 334,369 ee INDEX. PAGE 5,327 | Bones cuboid 839 | —— cuneiform 402 dorsal vertebra 487 | ——ethmoid . 256 | —— falciform . 507 | ——femur. . 794 | ——fibula. . 423 | —— first metacarpal . 653 ————— frontal * . . 491 | —— great cuneiform . i, | ——hamatum . 493, 923 | —— heart, of . 491 | —— humerus 493 | ——hyoid . ib, ilium . 491 | ——Aineisive . ib. incus . 7 493 inferior maxillary 491 | —— intermaxillary 327 interparietal 892 | —— ischium ib, lachrymal. . 826 large cuneiform 498 | ——- lumbar vertebra . 6 | ——lunare . 11 magnum 15 malar , 12 | —— malleus 18 maxillary, inferior 11 | ——— superior . a Beet dB metacarpals .*. 16,17 | —— metacarpus 11 metatarsus. i. | —— middle cuneiform . P ib, nasal - 10 | —— navicular . 11 | —— occipital P 13 | ——oscorone . . . 15 | ——— innominatum . tb, | ——-— orbiculare . . 10 = pedis 15 | —— — penis 9 | ——palate. . 17 | —— parietal . 14 | ——patella. . 12 . 11 | ——pelvis. . . . 10 * a am penial . . . . 15 | —— peroneus ‘ - 112 | —— pisiform 45 | —— premaxilla 102 | —— prominens . . 21 | —— pterygoid . 106 | = pyran dal . —- i i, | — : ; 80 | — oy 78 | —— sacrum ‘ 21 | —— scaphoid of carpus 27 |— of tarsus 27 | —— second phalanx 67 | ——vsemilunar. . 91 | —— sesamoids . . ome BORER fF Se DOr ee! we Sg lanes ee Be oF 8 9 Bones, smal] cuneiform . small sesamoid —— sphenoid — stapes. . sternum styloid —— supercarpal superior maxillary supermaxilla . —— tarsus . temporal . . —— third phalanx . —— tibia : —— trapezium . —— trapezoides —— tricuspid turbinated —ulnar . —— unciform ‘ —— vertebra dentata : prominens tricuspid vertebra cervical . —— —— coccygeal “fee > umbar . vomer . *. zygomatic . Botal, foramen of Bourrelet . Brachial bulb . Brachio-rachidian bulb: Brain. Bristles . Bronchi. . . cartilages . —— disposition form . —— glands . relations structure . volume . Bronchial cartilages | glands tubes . Bruch, membrane of Brunner’s glands Buccal mucous membrane . Bulbi fornicis vestibuli Bulb of ovary . of plantar cushion. —— of urethra Bulbus aorte olfactorius — rachidicus . Burse, serous Caducous teeth . Cecum . of mastoid lobule , of Morgagni —— pharyngeal INDEX. PAGE 104 | Calamus scriptorius 86 | Calcareous powder of vestibule. 39 | Calices . . stares 842 | Calyciform papilla warn. 66 , biflex . eer 54 | —— Fontana 79 | —— Gertner 44 | —— godronne Bo —— Haversian ewe 0 —h hthalmic 41 | —— inguinal . 84 | —— Jacobson 100 rivascular 79 etit 81 | —— Schlemm 23 spinal . 49, 442 Sylvius 76 | Canine teeth 80 | Canthi of eyelids 21 | Capillaries : 23 | Capillary system ib. | Capsular ligaments . 20 | Capsule of Glisson 21 oflens. . 27 | Capsules, suprarenal 24 | Caput gallinaginus . 25 | Cardiac cavity 51 ligament 47 orifice . ; 503, 916 | —— septum 803 re sheath 668 | Carpus 2 ib. articulations 672 | ——pbones . 797 movements 460 | Cartilage re 461 of the tongue . 460 | Cartilages, complementary fibro- 461 —— incrustation . s 642 interarticular _ 461 —— interosseous . eae stratiform wb. | —— cariniform ib. | —— cos 642 | ——ensiform . ° 461 | —— interarticular of j of jaw . 822 | ——semilunar . . 403 | —— Wrisberg, of . 332 xiphoid 678 | Cartilaginification 883 | Caruncula lachrymalis . 874 sublingualis Z 802 | Cauda equina 862 | Cava, vena 915 | Cavernous sinus . 692 | Cavities . 675 | Cell-germs 183 | Cells . — multiplication of, 348 | —— bone 407 | —— calcigerous , 692, 696 | —— connective . 335 | ——hepatic . 373 | —— medullary . re 2588 & @ Jeet Oy ONG. 6 «. @ ¢ & 6 a 23 a SEECRERREESSEREESS on s S885) ‘ : - 7 ris Pa ~ os ae ei A fel ee Pa Centrifugal conductibility Ke ee = Genital indict Phi i ib. é are ow 288 —— ovale of Vieussens 697 _ Cephalic ~ oa 893 Cerebellar crura . . 678 — peduncles. . . 675 —ventricle . . . 679, 683, 688 Cerebellum . . . . . 672,686 —— external conformation 686 —— internal conformation 688 Cerebral hemispheres = eee OTS — es . . 675, 677 a a SP) cas) RS — ; 692 — vesicles 907 Cerebro-spinal axis . 651 —— — nerves 700 Cerebrum Res Er fant, SOO — convolutions TAS . . 689,691 —— external conformation ee ea, O90 ae 689, 691 — structure . ~ 697 Ceruminous glands ib. Cervical ganglia 782 —nerves. . 784 — vertebra . 21 Cervix of bladder 491 — of uterus . 877 0 era 7) Chambers of the eye. . 817 | | Ve a 592, 356, 359, 360 ——functions . . . 332 SR eT AS ee 799, 812 Chiasma enerre. (6 vec? 8 Chorda Fac yee 892, 905 Chord# longitudinales . . . . . 693 mee Wocsies . . . . « «+ « 452 me Willisli . . . « '« « » 606 een ae skit 895. | Ss “er ae me—Offetus . . . . + » « 895 — definitive. . . . . . 896 ——primitive .... . t. Choroid membrane or coat. . . . 820 m— ——_- ——- anterior . . .. ib. — —— ——- posterior . . . . th —— ——. ——-structure. . . . 821 —— plexus, cerebral 693, 696 — zone . Se wer We Res og sxsw = 408 Mera Gl, (ORS Ciliated ey epithelium . > Circulation, adult — fetus . —— —— in birds . Circulus venosus orbiculi ciliaris Circumvallate papille . Cistern of Pecquet . . Clark, vesicular column of . Claws * . Cleavage masses. Clefts, pharyngeal . Clitoris . . — preputium ‘of . Closed follicles . Colon : double ig attachments — capacity. . . eparea.:.). 5 ae —form. . sta ——functions . .. length — tees structure —— attachment . — course form . —— interior. . . — —length... relations 6 of optic nerves of spinal cord . Commisures of vulva Common aorta Comparison of abdominal cavit y- —— of abdominal limb . . ——ofannexesoffetus . . . . of aorta. , —— of apparatus of taste , ——— articulations, carpal . coxo-femoral humero-radial —— —— interphalangeal . —— — radio-ulnar . —— —— scapulo-humeral tibia-fibular auditory apparatus —— axillary arteries —— bronchi. . earotid arteries cerebellum cerebro-spinal axis . . cerebrum .. external iliac arteries. genital organs, female —-- male —— head —— heart ~—— internal iliac arteries . ——intestines . . . —— isthmus of brain . —— larynx . liver Pata 4s TOnGG iy ms Koceed< 2 mouth. . i _——— muscles of abdominal region . — arm . — back . — —- costal region —— —— diaphragm . —— —— fore-arm —— — gluteal eS —— —— hand = —-— head . — -—— le ~ —_—_ shoulder : sublumbar region —-—thigh ... —— nasal cavities . =——— nerves, brachial plexus evapial . 4 — —— —— great sympathetic . —— —— lumboesacral plexus —— esophagus , , er pancreas . ’ ’ ’ —— pharynx : — Zane salivary glands : SPIO sso ops Oe ——spinalecord , . . —— stomach ve Ire —— thoracic limb . y RTs thorax, . PL Mie ey So —— thymus, gland . seid. ee OY —— thyroid gland, . . . , —— trachea oe Pi a tek —— urinary apparatus . ae wae a, + OS - INDEX. "382 Comparison, venous 522 | —— vertebral a Wi 385 | —— visual apparatus 187 | Complementary apparatus of f pedal bone 904 | Composite nerves . oo Se 538 | Compressor vesicule . ole Mae 814 Conarium . . . . . . wa 156 | Concha auris, 4 > ao 163 | ——— cartilages | : aes. 147-| ———— muscles. . « + 2 6) 159 | Conchal cartilage . o. 6 148 | Confluent of jugulars . . . .« . 144 | Confluents of subarachnoid fluid . . 168 | Congestion of liver . . . . . . 850 | Conglomerate glands . . . . . 574 | Conjunctive. . . . . ane 472 | Conjunctival tissue. . . . 5 595 | Connective cells . a 689 fibres .- «=e 666 | —— tissue .. . »s\ “ogy eee 698 | Consistence . . re 557 | Contractile cells eee 888 fibrille . ee 871 | Convoluted tube of kidney <. Ge 63 | Coracoid process o,f. wit 514 | Corium cutis Fae 545 | Cornea . . .- a) 417 structure of .' $. eee 685 | Cornu Ammonis ee ee 471 | Cornua of spinal cord sve 434 of uterus . is Shee 472 of ventricles eel ae 362 | Corona glandis .. eine 245 | Corone tubulorum . . «- . B47921 —germ... .. . . 348,921 — pulp . . 2. . 2°. + 845,347 936 INDEX. PAGE Differential characters, scapulo-humeral 144 | Differential as thyroid gland , —; sternal (cyt Oe d48 urinary apparatus... ) —— —— —— tarsal . 172 | —— venoussystem . . . . 620 — — —_— — temporo-maxillary 139 | ——- —— vertebral column . -) ae —_ — tibio-fibular 168 | —— —— visual apparatus . . 835,836 — — auditory apparatus . 850 Digestive or . » —— —— axillary arteries 570 ee —— —— brachial plexus 763 Dilator of tes por . a a —— —— carotid arteries 590 | Dissection of arteries . . . . . 873 —— — cerebellum 689 | Discus proligerus P .- Var S —— —— cerebrum 698 | Dorsal nerves - ee —— —— cranial nerves : 739 | —— nucleus of Stilling : pd M a envelopes of cerebro-spinal vertebra . a BXIB att Hs F 666 | Double-contoured nerve-fibres . - 652 —— ~— external iliac arteries .. 555 | Double semicircular centre of Vieussens 698 — —— —— genital organs of female 886 | DuctofStenon. . . . . » « SOT Sect Sete of male . . 867 of Stenson. . . . Vl) en — great sympathetic system . 789 of Wharton . . sy ———hed. ... . .. . 55 of Wirsung. . . « 5 a) ——-——heart . 513 | Ducts, accessory pancreatic J ae —— intestines a 414 biliary =... .. a0 oe internal iliac arteries. 543 Cuvierian. 2. +s — isthmus of brain 685 genital . 928 — liver. 432 | —— guttural 2” a an — lumbo-sacral plexus 777 mammary. .- . » +s —— —— lungs : 470 | —— Miiller’s . «oa — — lymphatic system : 645 omphalo-mesenteric > a — mouth 356 | ——parotid . . . . . . . BOT ———— muscles. . . ——perspiratory . . . . . . 794 aa abdominal region 245 | ——'salivary . . . . . . 867,369 —— —— —— anterior foot . 279 thymic ay” *) —— ———_ —_— alm > . 260 | Ductus ad nasum oe oe a axillary region 235 arteriosus. . . . . « 470,916 | —— —— —— cervical region 201 choledochus . . . 9s) j5eee — —— —— — inferior . th, | —— course . . 404) a) eee i —_— — — superior ib, | —— structure . . . . sw m@o —— —— —— costal region . 238 cysticus » 5 ws sw oe diaphragm. 248 ejaculatorius . . . . 860, 861 — — facial region . 228 | ——galactoferus . . . . . . 884 —— —— ——- forearm .. . . . 270 | ——hepaticus. . . . . . . 423 — — —— eo — 5 ee lactiferus : Flan . 884 —— — —— head . . 228 | —— lymphaticus dexter . 614— — — — hyoid | region ‘ 230 | —— pancreaticus minor 428 — — LY ee 306 | —— prostaticus a 864 —— —— —— masseteric region 229 | ——Riviniani . . . . . . . S369 ——— -———- —— panniculus carnosus . 187 thoracicus. . . } =n —_— — shoulder . 254 | —— venosus of ‘Aranzi. . “ee 2 SOIers —-- spinal region . 209 | Duodenal glands . . . . . . 408 — sublumbar region 215 | Duodenum . ... . . 6s) —— ——_——thigh. . . 294 | Duramater. . . . . « « 660,661 —— —— — tunica abdominalis 240 structure . . «| ss) Gun —— —— nasal cavities 448 | Duverney, glandsof . . . . . 872 —— —— esophagus 380 — pancreas 434 | Ear, external . 3s a —— —— pharynx 876 internal nerves of... 837, 840 —— —— posterior aorta 535 middle. . .- +. 0h eee ee limb 105 | Ear-dust . 7 et (a -—— —— salivary glands 370 | Ectopie of testicles. . 853 —— —— spinal co 672 | Effluent canals of dura mater sinuses . 608 a spine 135 | Ejaculatory ducts . 860, e — spleen 434 Elastic fibres é — stomach 393 | Embryo-cells ? got — thorax oe 70, 466 | Embryogenous vesicle . : 890 —— —— thymus gland 5 Ah art 476.) aibryology- 2 ww et th, INDEX. 937 892 | Fascia infundibaliform . SRS 0 BES ta xy . 11 | —— transversalis oe ew 65 242,245 ‘845, 346, 921 | Fasciculus, primitive . . . . . 178 . 347,921 | Fatty nucleusof Baur. . . . . 337 127 | Fauces , eo get te eee isthmus of. Stats ve? bee ib, 662 | Femoral region. . . . . . . 283 666 | Fenestracochleaa . . . . . . 838 672 ovalig..).° . s *. (88% 840,38 ih. | ——rotunda . . . . - 838, 840, 842 ib. vestibuli . . .. . . . 837,842 ib, | Fenestrated membrane. . . . . 519 OT.) Petlonks Ge Apr. &. &2) MS ABT >. | Fibres . , OD) vot, a ES 4 ib. of Remak . s - « '~ 652,782 511 Fibro-cartilages, complementary oss. koe ; 837,840 | ———— intervertebral . . . . 130 67 | ————-pedal bone . . . . . 801 660 | Fibro-intestinal lamina. . . . . 906 : 668, 683 | Fibrous tissue . a F, Sana — rey 795 | Fibrous zones ofheart . . . . . 508 796 | Filiform papille. . . . . . 336,814 i. | Filumterminale . . - . 665,908 858 | Fimbriz of Fallopian tube. . . . 876 859 | Fimbriated norris of oviduct . . th 451 | Fissure of Bichat . een interlobular . . . . . . 690 interpeduncular . . . . . 678 327 | ——plantar . . .« . . . « 85 ofSylvius. . . . . . 691,692 i, | Fissura glaseri Be DTS ae ib. longitudinalis, inferior . . 668 ib. | — Superior) a ee wb. |°——palpebrarum . . . . . . 881 ws. |) Pleecolus: cs... . be ne ee ib, | Fluid of labyrinth » + > |.) 840 ib. | Fetus, development of. . . . . 905 - . 578 circulationin. «© . . « . 915 797, 802, 812 | Follicles, aggregated . . . . . 405 «tw 689 OMG. « -t eo) eee 816 | ——hair .. 798 691, 692 Lieberkiihn = 403 447 | —— mucous. 2 327, 391 841, 844 —— simple . . 506,514 | ——-solitary . . . . . . 329,404 846 structureof . . . . . 329,402 817 ultimate . . 2 . - 3865 832 | Follicular glands. . > 5 eae cavity of clitoris... . 882 839 | Fontana,canalof . . . . . . 821 832 | ForamenofBotal . . . . . 503,916 cecum of Morgagni . . . . 335 of Vicq-d’Azyr . . 658 —— commune anterius .. . . 680,682 882 FAST ene Stones aeee 876 | —— —— condy oid ; - © « 8 i. | ——infra-orbital . te ee ee i. | ——intervertebral . . . . . 2 40 34 633 | —— lacera basis cranii. : 440 | —— lacerum, anterior . . . z | + . le 662 | ——Monro,of. . . . 682, 693, 694 | 345,350 === BOERS See IB Foramen obturator . —— occipital ovale . . ——rotundum. . —— Soemmering, of weer spinal . . spinosum . . —— stylo-mastoid . —subpubic . . subsphenoidal —— supercili —— supersac supra-orbital . —— trachelian vertebral . Winslow . . Forceps major Fore-arm, bones of . Fore-foot, bones of . Fore-lock Formation of embryo Fornix . : Fossa centralis retine . ovalis .° . navicularis Fossulate papille Fourchette . . Fourth ventricle of brain Fovea centralis . Frenum lingue . —— preputii Frog of hoof i Fay Ree Frontal iinet Functional ae of lungs Fundus of bladder . Fungiform papilla . Funicular ligaments _ Furrow, primitive . Galactoferous ducts —sinuses. Galeati’s glands . Ganglia . —— cervical, inferior . middle superior . - —— hypoglossal —— inferior cervical intumescentia —— jugular lenticular . —— Meckel’s INDEX. PAGE , 93 | Ganglia, middle cervical — . : : 34 | —— naso-palatine . . é 40,503 | —— ophthalmic oe pt eee 40 —— otic * . . . . 836 a ma petrosum . . . 19 | —— semilunar Fn 40 —— solar . . . . 43 | —— spheno-palatine .-> 93 | ——submaxillary. . ... . 40 superior cervical... . 36 | Ganglion cells . 2 . 27 | Ganglion, intercarotid . . . . 36 | Ganglionic nerves i rel Aa 34 | Gasserian ganglion . s hae iw. | Gastro-colic omentum . > a 39 | Gastro-hepatic omentum - ae 383 | Gastro-splenic omentum . ae .699 | Gelatine of Wharton. . ao 75 | Gelatinous substance of Rolando . 77 | Gemmation. . . . ~ oe 797 | Generative apparatus . ebay . . - 905 of Birds . o. 7: ia 679, 692, 694 | Genital duct . . . , 4 cae itn!) $e OBS gland . ae . hee 506 organs ‘of female . -— 8 862 | ———— of male . oe WEEE 33 tubercle ‘ vino ae 88 Genu of corpus callosum P| * 678 | Germ of hair > 836 | Germinal eminence . . aa . 335 —— spot . . . . ib, = “=i . 872 a ee be . 875,325 0 ae . 807 | Ginglymus . . . . . + . 807 | Glandule agminate > a < ‘4 . 813° solitarie +. “es Se . 446 | Glands . . . Rea om : . 470 agminated .. .. .. « 6 = rr . 491 Bartholine, of —.... . . « 88F) * 336, 874 brachial : . . + ee 125,126 | —— Brunner, of . os oe . 892 | —— vais, >) i —— ceruminous . « 884, 885 | —— cheeks, of . ~~) pa ib. | ——coccygeal . . . «on 403 | ——colon,of . . . =» 780 | —— ect . + «0 ae ib. SS Cowper . . . * 864 727 oatenaean of Pig .. ae 720 eS duodenal . . . . . . . 7 j 784 Duverney, Of)... “ ia . 722 | —— int . . 6a 728,729 | —— interungulate « of Sheep 764" . 718 | ——labial . ‘B31, 339, $20.4 Gs 719 | ——lachrymal | - 834 Globus major epididymis —— minor , Glomes of Glomeruli of * _ INDEX. PAGE . 455 | Glottis . x ‘i gle a . 404 | Gluteal aponeurosis nee he | . 403,410 | —— region. . . . . . . 335, 370 ME: ane . . 419,642 | Graafian vesicles . .» « 829 | Granules, fat - + + 632 | —— pigmentary - « ». 884 | ——proteic . . .» 367,371 | Great lymphatic vein . « « 832 | —— sympathetic system . 369, 371 | ——- —— structure . : . 891 | —— transverse cerebral fissure . . 372 | Grey nerve-fibres - « « 445 | —— root of optic nerves . « 4» + 663 | —— substance of isthmus .. . . 343,370 | Gubernaculum dentis 427 | ——testis . . . 1. 1 "365, 370, 371 | Gum. . ‘ aes 404 | Gustative bulbs . . « B9L | —eells . 794 | Guttural pouches . . 404 | Gyrus fornicatus . 643 . « 680 | Habene . . . 445,681 | Hamal arch. . . 640 | Hematies a» 867 ire 2 Gok . . 640 follicles = . « 643 formation of . . « 644 | —— functions . * PAP? . . 864 PORN OS, ae eka (eyes . 329, 339 ee Se ee cake BAO sheath of . . . 364 | Haller’s passage - . 829 | Hand . . . 872 | Harder, glands of . 404,410 | Harmonia suture . . 642 | Haversian canals . 870 | Head, bones of . 641 | —— in general «re ae . 644 | Heart .. 369, 371 action . F . 638 | ——eapacity . . ‘ 367, 371, 644 | ——direction . .~ 4 . 794 | —— external conformation ‘ 642 form . ae : 473 | —— general sketch 4 472 | —— interior 4 F . 459 | —— nerves and vessels of . . « 829 | —— serous membrane . 879 situation 880 | ——structure . 887 | —— volume ; 365 | —— weight. 4 | Helicine arteries 882 | Helico-trema . F i 862 | Hemispheres, cerebral ; : 73 | Hepatic cells ‘ ¢ 422 | ——ducts . ; 891 lobules. « 859 | Hernia, inguinal 4 ; >. | Herophilus, wine-press of . 807 | Highmorianum, corpus . 488 | Hilum of kiduey Rf ey SON ee A ee eee et ow en ed a * so oe 58)" @ 940 INDEX. . PAGE Hilum pulmonis. . 466 | — vy Hippocampus . . 693,695 | Intestines, large, attachment . Hi anes . . . . . . 897 eS . . . Hollow organs . . at 326 PRO na 5 Chir hoe —— structure of ib, | ——-——direction . . .. Honeycomb glands . 404 | ——-——- functions . . . Hoof . ‘ots 800 | ——- —— interior . . ——contentsof |. 800 | ————relations . . . ——- description of . 805 | —— —— situation + em development of 810 | ——-——-structure . . . structure of 808 | —— small . - “ —— wall of. 805 | ————— attachment... Hoof-horn ie Wee 808 | ——-——course . . . . structure of . ib, | ———— development . . Horn cells . . . 809 | ——-——form ... . Horns, frontal . 813 | ————functions . . . Horny production . 799 | ————interior. . . . Horse-hair . . 797 | ————relations . . . Humours ofeye. . 817,827 | ——-——structure . . . Hyaloid membrane . . 827 | Intralobular veins . . : Hydatid of Morgagni_ . oe 2 eee See ee et : aban cand canals 834 structure of : ‘ Hymen . . 883 | Ischiaticspine . . . . . Hyoideal region . eer 225 | Isthmus of encephalon . . 67 Hypochondriac region . 381 external conformation of Hypogastric region . ib. | ——- —— internal conformation of Hypophysis cerebri . 681 | —— structure of. . . of fauces . AT a c. Tleo-cxcal valve 408 | Iter ad infundibulum . . Tleum 401 —— quartum ventriculum Imprint... te 2. an ey re — isor teeth . "$44, 349, ‘357, 359, 361 ~ Incus 842 , Inferior umbilical ring . 894 ene pening 3 * ia Infundibuli of lungs 468 . aaa Infundibuliform fascia a58 | ee eS ee peace! $ oa Farad’ channel . . sega 547 veg. 2) a eae —— ring 5 242 ; Injection of arteries 520 | Keraphyllous tissue . . . of veins 599 | Keratogenous membrane . . Inosculation . 517 | Kidneys. . “ Insule . 635 conformation, external, Integuments of external ear 850 | —— internal, . ; Interarticular meniscii . 163 | ——development . . . . Interauricular partition é 503 fanctions ,- . <) ssc Intercarotid ganglion . . . 789 | ——primordial. . . . . Interglobular spaces of Czermak 845 | —— proper tissue. . . . Interlobular fissure . : 690 | ——-relations . . . .. veins . . 423 situation . . a Internal crural region 288 | ——-structure. . .. .» —ear ... 837 | ——tunic . . . «je —— — nervesof . 840 | —— weight . .... Interosseous cartilages . 124 | Krause, corpuscles of ag Interpeduncular fissure 678 | —— —— terminal genital . Interstitial substance . 178 : Interungulate gland 794 | Labiavulve . 2... * Interventricular septum . . 503 | Labial glands . . . . .« Intervertebral erica: 130 | Labyrinth . «© «. « « — foramen .. * 24 | ——-osseous. . . . « . Intestinal groove . . 894 | ——membranous . . .*. Tutestings 2 os5,.0 ce fab see 400 |, Lachrymal apparatus . . . ——development . . .. 920 | ——canal. . . w. « we Oa. 8 Oot tbe _ aS + . yy % S, Ino a ee & ot ae, Oe a ik’ . \ i 4 ' - i IF y , * : « - 7 pd “. » in - > oO C : c > ae f ‘ eg _ > ~_ a: * al ~ Sh OC > = mw G ao / . >; S< = A ~ . - b 7 . ~¥ > “4 ee f .- * < = x 4 we ¢ 4 fa }e, i > 6 > ld = “ ~ ‘ , S oe > Sel tes Ce see t,. - A Spay . ~~ s > ‘aut, oF vA Z i Fax : ~ “ a oe . A A * Che yer ale - “ - : i< | “3 2 : “ 3 . a i ~ 2 2 ; ~ < 4 1 a2 ‘ - . t > aka ce > . 7 ‘ . € ‘ *. £ ow en 6 a. eS 95 > So Sl aa E s£2s8S2 282285 7. oo > & ae -_ - e PAGE Ree 834 — * . . 711 - . . on os 834 * i E 831 aa 402 ‘ er at 884 850 © . 683 708, 818 819 838 804 ib. Lancisii, heede Yongitudinals ‘of yes . 449 —— articulations . % 451 — development . 918 entrance . 456 —— external surface ib. . 449 functions 4 . 456 —— internal surface . . . ab. a . 453 ca 455, 734 oy Te . 449 Ae 450 > Saree 456 Sr 455 - ee 925 Lateral columns of spinal cord oa 2 0 j 807 ——lamine ofembryo .. . . 905 fasciculus of isthmus. 678 — gis. <-+ » 692,696 Left auricle of heart +d TAT —— ventricle of heart 506 bones of . 100 —musclesof . 288 Lens, crystalline ‘ 826 —— —— capsule of 826 — — structure of ib Lenticular ganglion 718 —— glands - 404 —— papilla . 336, = cea poly follicles 403 —glands. .. id. LIGAMENTS . . . 125 ——- capsular . ib. — funicular. & ib —— general considerations a. —— interosseous . 126 —— membraniform os — peripheral ib, Secwhie. ib. a yellow P 126 —— anterior of carpus 148, 149 _—_— aoe 522 — o-metatarsal 171 —— ieceaa, inferior 136 —— —— superior ® INDEX. 941 PAGE Ligaments, ape aid 842, 843 —— bladder, of. . 491 —— broad . aerate 384, 877 — caleaneo-astragaloid ; ae —— calcaneo-metatarsal 171 —— capsular of atlo-axoid ‘articulation 136 — of carpal Ps 151 —— —— of costo-sternal 141 —— —— of coxo-femoral 162 —— —— of femoro-patellar 165 —— —— of humero-radial 146 —— —— of hyoideal 139 — of 8 ER A 154 — of occipito-atloid > 137 —— —— of scapulo-humeral “e 143 —— —— of temporo-maxillary ,, 138 — of vertebral ae 134 -——eardiac . sone Sem — carpo-metacarpal . . 150 carpal, anterior 148, 149 cervical . 132 chondro-xiphoid 142 ciliary . 822 —— common 151 — inferior vertebral 131 — superior cervical ib, — superspinous 132 —— costo-sternal, inferior 142 —_—_—— superior 141 —— costo-transverse, anterior ib, —_ — posterior . ib. —— cotyloid P 162 coxo-femoral . ib. crico-trachealis 453 cruciform . 137 — cuboido-cunean . 171 cuboido-scaphoid . ib. denticulated 665 —— diaphragmatic. 922 —Fallopii_ . 241 —— femoro-patellar . 165 —_— ne a é 335 epatic got - 420 —— hepatico-renal ; 383 —— humero-radial, external lateral - 145 — internal lateral ib, —— ilio-sacral, inferior 159 —— — superior * ib, —— interannular - 1833 —— interarticular costo-vertebral - 140 -—— intercarpal = is, ae ——interlamellar . - 133 — re ag of carpus 148, 149 —— —— radio-ulnar . . 147 — iaterphalangea first . : 157 an eee . i. ao sradeecsa ly 153 —— interspinous 133 —— intervertebral 131 —— latum pulmonis . 467 nuche . Pa f°: —— lobus Spi ii, of : - 883 —— lumbar sere Wolffiani . oS ae — met geal 4 942 , » "186 Ligaments, odontoid. . . . . . ——— ovarian . . ., ». » ©. 884,878 ——— zor Coreen aleta ber wa ie kx a of OR ee ere 819 jerperal ‘inferior 140 = pee 241 os La serene 4 162 ——radio-carpal . . . . 149 —— radio-ulnar, interosseous. . . 147 — peripheral, re — external transverse . 1b. —— round, of uterus « 384, 877 a ee sacro-iliac . . . . . . . 159 —— —— ischiatic . 160 —w—sceiatic . . . 2. « . ——. seanhoido. 171 —— sesamoid m8 153 —- inferio? .00 <) rig toes oa lateral 154 spleen, of . ~- . -429 stellate ’ . 140, 141 — inferior... isi. /~. 142 subflava . 133 superdorso-lumbar 132 superspinous cervical . . .~ 1. suspensory of fetlock .. . . . 154 ——- of penis . 865, 866, 872 oa of sheath Po wt ee) BEF aa of uterus 877 _—— tarsal . F i68 —— tarso-metatarsal, posterior 172 —— teres . a A 162 —— tibio-fibular 167 —— tracheal 459 —— transverse. . 136 — umbilical . . 491 —— uterine, broad... |. 884,877 —- round : ib, —- elgg’ “ 877 —— vulvular ‘ 884 Wolffiani, of corpora F 922 Limbs in general 3 Me 109 their parallelism .. 110 Limitary membranes, 5, 327 Linea alba ; 239, 240 Linew transverse . . .-. + 693 Lingual canal . . . 1s 334 glands . oo tes 370 macy . a 835 —lacune ‘ 335 —— mucous membrane 814 Linguetta laminosa . 679 OTS Pee ee ee 330, 356, 359 —functionsof . .. . 332 stractore Of i6° jcsciets as. . 881 Liquor amnii . 896 corns «4 ON . 820 collicall. a NS aes . 873 —— labyrinthi . 5 . 840 Morgagni . . 826 seminis . . 858 Livet. 735795. . 419 attachments . 420 development . 427, 922 Liver, direction. . —form ... —— proper tissue . “ ee iii . . . —situation . . .. . = structure . . . . . —-weight . .... Lobes of liver Ope (9.24.06 Lobular bronchial tube... Lobulated glands tied Lobule, anterior of lung. Lobuli testis . = Lobulus pneumogastricus > Lobus Spigelii . . oe Locomotory apparatus . .. . Longitudinal fissure of brain . Lowenberg’s scala . . . . Lumbar nerves. . sa vertebra . or ee Lumbo-rachidian bulb . . . Lumbo-sacral plexus . Lungs * ot ee — development 2° lee form > ee — functions . . rte fundamental tissue a e general disposition . . —relations . . . . . . —serousenvelope . . . . situation ot | om Sse — structure. . 2. 3 sO Lymph . $ Lyaghatle glands and vessels . —— course 4% etd) oe Poet Cy fie eh ee eg ef ee ee ee be : op met , 1 = = 5 — — origin plexuses . a preparation of Bh : : —— —— rete mirabile. —— — — structure. —— —— — termination . Lymphaties, Birds, in . oi —— bladder, in «yet bone, in’ <. 2° = Tae —— brachial o> Oe bronchial . : —cecum,in, . om colon, large, in “a. —. emall,in. < + a —— guttural 5 ay —— heart, in PUG s — hepatic lobules, in Ss — iliac nih Pee teh meal inguinal, eep . . . a superficial ort ie —— intestines,in . .« . 641, eS kidneys, in . . . . . ———_ li in . * er Soec; in . . —— lungs, in —— mucous membranes, in in : . ae ee | pes 4 . 691, 692 . + 800 367 846 442 882 ib. 912 719 427 807 606 464 PAGE Mediastinum, anterior . . . aaa —— posterior . ae ae ie Mapulla of Bones. 4- .. «s « TAS Medulla oblongata . . . . . 675,676 Medullary cells... . .. . «+ 5 415 —— layer of kidney $s (iad ce gt =e Medullated nerve-fibres. . . . . 652 Medullo-elig 45-0) +) sce Se Meibomian glands . .. . 830,831, 832 Meissner, corpuscula tactus of . . 794 Membranadentata. . . . . . 666 —granulosa. . . . . . . 873 ms PODOD Go. ve ves Cup x +s 0 OGRE ee —nictitamns . . ... . . 833 ——pupillaris. . . . . . 824,909 —tympani . . . - % . « 841 ——— secundaria . . . . . 842 ——vitellinn . . ~~) 838 Membrane of ae humour. . = SRF —— basilar SP Rte SL a0 oe ee ee —— Bruch, of . 4 a eestor, Fr ae oS HE Sh ed oss > ee conjunctival... es.) se BBB poets Corel Of sO at Sls 2 Vet 1688 ——Demours,of . . . . . . 827 —dentated . . .. . . . 662 —— Descemet,of . . . . +s « 827 eo OG OF. wk te MN -a ~OIE fanentrated’. o..Taie Se ie “ID —hyaloid . . . . 1's « 827 —keratogenous. . . . . . 803 —S—mus0ns gs ST eee SRE aa Relamer Of | ke sb oo 880 —— serous. . pod ek ee SRS Membranous cochlea. . i+ age Coe —semicireular canals . . . . i —urethra .. jr hy Pe” SR WRUNG . 2. «delist ers ioe Meningeal ulations . . . . 663 of cerebro-spinal axis . . 660 Meniscii, interarticular on PE Mesenteric glands . . . . . . 641 Mesenteric lamina . . . . . . 906 ee > at eee 383, 401 =——olio , 9. 6 ws "283, 384, 413 ——propr ... . 383 Meso-cecum 2. ww ss . 383, 407 Mesocephalon . . . . . . 675,677 ave = bs. a Be. ~~ S88 Meso-rectum . . 413 Metacarpo-phalangeal sheath 267 Metacarpus. . . . 81 Metatarsus . . 105 Middle cerebellar more . 678 —— septum ‘of nose ot bo atte ee SSR —— ventricle - brain.g?-.) s! > @* 689 Milk . <4 ce: ee SSS Milk-fountains . a. eerie rn ae Mitral valves’ 2k we hte er BOT Mixed nerves. Saeed He 700 Modiolus 838 O44 INDEX. PAGE Molar teeth . ... . «. 352,359,361 | Muscles, structure... . . Manorchids . .. sinis. vy Sia ee ——— tissue. 2-46 ss SUM Monro, foramen of . 682, 693, 694 — uses . 4x, ee Mons veneris . sieve « OCR — vessels and nerves gu Morgagni, cecum of 5 335 ——volume .... . liquor of 826 | —— accelerator urine. . . . Morsus diaboli 876 | ——adductorofarm . . . ,. Motores oculorum 708 | —— adductor femoris . . . . Mouth SAK 330 | ———— longus . . ... development of 920 | ——-——tibialis . . . . . SG GOSPEL Su owns) codes 355 | —— alveolo-labialis ne Mucous derm ae 327 | ——anconeus . « ne kar corium i ib. | —— angularis scapulee < one ——membrane. . 326 antea-spinatus . gre — of bladder 493 | —— —~ constrictor of vulva — of bronchi 461 extensor of metacarpus — ofcheeks . . . 331 | ——— of phalanges . . — of Fallopian tubes . 876 | ——-——medius . ous — of guttural pouches. 845 | —— straight of thigh. Te — of internal ear . 840 | —— ulnaris: 5. 6s 3 7m —- of intestines, large . > 410 arytenoideus . . . . —_— — smalles «. ~ 9 fre 402 | ——aryteno-pharyngeus . . oe of larynx 455 | —— basio-glossus . . . . — of lips 331 | —— biceps abductor femoris . —— —— lymphatics in 629 | —— brachial biceps . < ts —- of mouth 355 | ——pbronchial . . . 4. tery — of esophagus 379 buceinator . . oe — olfactory 444 bulbo-cavernous . oe = of pharynx . . . 374 | —— caput magnum x — of sinuses of head . 447 | —— medium . 6 — of soft palate 343 | —— ©: .s! Wein — of stomach . 390 | ——ciliaris . are — of tongue 335 circumflexus palati - ee — -of trachea 459 | —— common intercostals . . . — of tympanum 844 | —— complexus major. . . . — of ureters 490 | —— minor . . oo — of uterus . 879 compressor a --- of vagina 880 | —— oer Soe one of vulva. 883 | —— vesicule Miiller’s duct pate 923 | —— constrictor of pharynx, Multipolar nerve-cells . 653 | ———— inferior . . Muscle-plasma . . ; 181 | ——-——- —— second middle . Muscxes :—striped in general . 174 | ———— —— superior Shake — action : 182 | ———— ae. . —— attachments . 175 | —— —— vulve, anterior . —— appendages ; 183 | —— terior: 2 ns classification. . . . . # coraco-brachialis . : contractility . 181 | —— -humeralis . ‘ development . ; , | 181, 913 —— direction , 175 form. . 174 —— general table of . 315 ——inBirds. . 313 — insertions 175 ——lymphaties . . . 180 —— manner of studying . 183 nomenclature . . 176 —— physico-chemical properties. 180 —— physiological eae a 3. 210; —— preparation of . 184 —— preservation of , 185 relations . 176 —— situation . 174 —— corrugator supercilii . cremaster . . crico-arytenoideus lateralis — posticus . —— ——pharyngeus. . thyroideus . Se hitic: , Sve triceps. . — pate coccygis . —— dartos . — deep flexor of phalanges ; —— banc. gluteal... : —— depressor cocey geus —— — labii inferioris ne CAP TO Le ee 2 eS Ces ® *g) kT eee ~ = > Win S TES ot i ie , Se Cha en ee eA ae oe ONCE NAM. Oh ee ee. 6 a —— external flexor of metacarpus intercostals . —_- — — oblique of abdomen —_— —— —— internus gastrocnemii : —— gastrocnemius externus —— —— internus . of pelvis ‘ — —— of tibia . lossus . ossus . —— — hyoideus —— gluteus externus . —— —— internus . —— —— maximus -— — 4 — ge of thigh . — ta anterior straight of of head ——- —— complexus ——— hyo-glossus. . . ——-—-0 Hane, of abdomen of head ? —_ —- rectus, of abdomen ° — — serratus , supermaxillo-nasalis —— heart, of : —— humeralis externus —— hyo-epiglottideus . —— —— glossus brevis — —— —— longus . —— —— pharyngeus . 3 P INDEX. 945 PAGE PAGE 222 | Muscles, ri oe ag re deat: 453 245 hyoideus magnus. . . . 227 225 | —— parvus ib. 221 | —— iliac psoas. . . . - 212 ib, | ——iliacus. . tb. 882 | —— ilio-spinal. . 206 216 | —— internal flexor of metacarpus 266 864 | ——-—— intercostals. . . 237 262 | —— —— oblique of abdomen 242 263 | —— obturator 292 298 | ———— pterygoid 224 264 | —— vastus... 285 265 | ——interossei . . 278 237 | —— intertransversales lumborum| 217 240 intertransverse of loins ib; 292 | —— Of 1ieck 3. RED SP waning OR 224 | —— intestinal . 402, 212, 414 285 | —— intrinsic of tongue 337 337 | —— ischio-cavernosus é 864 284 | ——-——-coccygeus . 217 186 | —— —— urethral ‘ 863 255 kerato-glossus 337 265 | —— kerato-hyoideus 227 266 | —— labialis. F 217 ib. lachrymal 320 300 | —— lachrymo-labialis 220 311 | —— large extensor of fore-arm . 258 305 lateral extensor of arse bi 264, 298 306 | —— lateralis sterni 236 268 | —— latissimus dorsi 4 203 267 | —— levator ani 3 863 431 | —— humeri . : ° 197 389 | —— labii superioris . ‘ 220 302 | ———— menti . F 222 ib. | —— palpebree r 832 304 | —— levatores costarum : 237 293 lingualis F r 339 302 | —— superficialis . Z 337 293 | ——longabductor ofarm . . 249 338 | ———— adductor ofleg. . 288 ib, | —— extensor of fore-arm 258 226 | —— flexor of fore-arm . 255 280 | —— of neck . sig 200 282 | ——; longissimus dorsi. . . 206 281 longus colli ; 200 ih. | —— lumbrici ; 278 289 |.——masseter . . : 223 291 | —— mastoido-auricularis . 849 199 | —— humeralis 196 191 | —— maxillo-iabialis 222 203 | —— mento-labialis : = ib. 337 | —— middle extensor of fore-arm . 259 248 | —— mylo-hyoideus ; 225 193 | —— nasalis brevis . 221 212 | —— —— longus . 220 248 | —— oblique extensor of metacarpus . 263 236 | —— flexor of metacarpus 266 221 | — —— of phalanges 306 509 | —— obliquus capitis anucus . 199 256 | —— —— —— inferior 123 453 | —— —— —— superior 194 337 | —— —— externus abdominis 240 , | ————— internus abdominis 242 74 | ———— oculi inferior 830 946 PAGE Muscles, obliquus oculi superior . 822 —— obturator externus . . . . 292 ——-——inmternus. . . . oe —— occipito-styloideus . . 227 —— eso : 379 — omo-brachialis . 254 _ hyoideus . 198 — orbicularis oculis . . 832 Leena oris . . . . . 217 — ——palpebre .. . 831 — orbito-palpebral . 832 —— panniculus carnosus - 186 —— palato-glossus. . . 839 _— A corte = 342, 374 —— ——-staphyleus . . 342 —— palmaris magnus . 266 — pectineus . : 289 —— pectoralis magnus. : 233 — —— parvus ° - 234 —— —— transversus . whe 231 ——pedal 6 . 5 ws peg? CBSA —perforass. . . . 268, 302, 568 —— perforatus . 267, 304 —pericardium . . ‘ - 9512 —— peristaphyleus externus . . 343 — internus. . > ti —— peroneus eb le - 298 —— pharyngo-glossus . - 339 — staphyleus . . 342, 374 —plantaris . - 304 —— popliteus . . ot tial ee —— postea spinatus . wow Bb —— posterior constrictor of vulva 883 — —— great rectus of head 195 — — medias. 222 — —ulnaris . 265 —— protractor of sheath . 868 —— psoas magnus . 212 — —— parvus } 214 — pterygoideus internus 224 —— pterygo-pharyngeus . 374 —— quadratus cruralis 292 — lumborum 214 retractor ani . 414 — oculi . 827 ee of sheath 868 —rectus. . “re 284 _— abdominis o SU ee eee — —— capitis anticus major 199 —_— minor . . ib. — —— —— posticus major - 195 —_ minor tb, — oculi externus . 829 _— inferior ib, ee internus ab. — — — posterior . 828 — — — superior 829 —— retractor oculi 828 ——rhomboideus . . . . . . 188 —— sacro-cotcygeal He: 215 —_ — eus inferior . 216 AREER ais ib. — — superior ib, ‘-———- —— lumbalis 214 —- scuto-auricularis externus internus —— semimembranosus —— semispinalis dorsi . ——semitendinosus . serratus Magnus . short abductor of arm adductor of leg . —— —— extensor of fore-arm flexor of fore-arm . — small adductor of thigh . anterior rectus of head anterior serrated . ———-complexus . . . —. extensor of fore-arm — —hyoglossus . . . lateral rectus . . oblique of abdomen ofhead . . —— —— posterior rectus serrated . . . . . . . . * pBatEE —— —— psoas js — —— scapulo-humeralis ¥ supermaxillo-nasalis —solearis . . 1... soleus . wy sphincter ani. . . ine . spinalis colli eg ©& oo 2 “Cre Wise 6) Othe (oe ee ee A Cee Se oS. 88 78 * . - >a aye o ¢. Se 7 te A} a 4S Se OC Le, yee Dy C25' «6 «2 @. Gass ie stapedius . . ee sterno-aponeuroticus : costales . —— —— humeralis —— —— hyoideus — — maxillaris prescapularis . —— —— thyro-hyoideus . — —— thyroideus trochineus stylo-glossus . hyoideus —— —— maxillaris : pharyngeus. . . —— subcutaneous of neck sublimis of phalanges —— subscapularis . subsonpule-Wickdien subspinatus . supercostals . . — superficialis costarum en nape gluteus flexor of phalanges pectoral superior constrictor of pharynx. > —— supermaxillo-labialis . : —-— superspinatus . —— temporal . = temporo-auricularis externus Bee mess he hie ak os se Bre. 4 6, | Fe . . . . . . . . . . . . 267, 304 x; 7 oe. 2OQ2S a _—s vy Euee & as # a BEEsESEEE PBs se Bes SERRES —— transverse of abdomen ue wos Of TiDS . —— —— spinous of back and loins —— transversus perinei —— trachelo-mastoideus jus . : — vagina, of . F . : —— Wilson’s muscle A M eell-fbres .. — tubes . . NERVES :—cerebro-spinal —cranial . . —— distribution . — division . —_ a —— termination . vegetative life, of mca os peaes exteneee bree BB ts trochlearis A —— maxillary, inferior Nerves, in Birds —— abducentes —— acceso —— —— of internal saphena . ——acromial . .. .- | er ——angualaris . —— ae ss brachial . femoral . gluteal . tibial auditory . . . auricular, anterior middle —— —— posterior — axill —— brachial, anterior . —— buccal. . 3 ——cardiac . chorda-tympani —eciliary. . —— circumflex —— clavicular . — coccygeal . — ear. —- collateral-dorsal —— crural . ; wa cubito-cutaneous : —— —— plantar . — dental . —— —— anterior . —— —— middle —— —— posterior. —_— eee. — digastric . P —— dorsal, collateral . —_ — great a —— femoral, anterior . nas Samo ae: —— small . — ae é —— glosso- ngeal . — Silat, harynge , —— —— posterior — gustato: —_— Srcaiekebigt * —— hypoglossal — — great — —-small . — iliaco-muscular —— inguinal, external —— —— internal . —— infra-orbital . —— infratrochlear . —— ischio-muscular —— Jacobson’s . of external saphena : 3p 2 948 Nerves, maxillary, saree: —median. . mental = Nee — musculo-cutaneous ‘ ——— s — ee —— nasal —— obturator . —— occipito-styloid —— oculo-motor, common — external — — — internal —— esophageal — — recurrent superior . —— olfactory. . ; ophthalmic of Willis , —— optic . . orbital. —— palatine, anterior . —— —— posterior —palmar. . —— palpebro-nasal —— pathetici pectoral . . —— perforating intercostal —— peroneal cutaneous —— petrous, great deep superficial pheumogastric . —— popliteal, external —— pterygoid, internal —— pudic, internal — radial . — recurrent , ome —- esophageal « —— respiratory —— — internal . —— rhomboideal —— saphena, external . —— —— internal . —— spheno palatine ——spinal . r a accessory —— sg AE great . eee Sees wee — re hyoid subclavian INDEX, PAGK f 712 | Nerves, sublingual . . . - 759 | ——subzygomatic . - » 717 | —— supe ular. , . 774,757 | —— temporal, anterior deep . 7s | —— middle deep. . . 717 | ———— posterior deep . . . 713 | ————superficial . . . 771 | ——thoracic, inferior. . . 725 | ——-——subcutaneous . - 78 | — superior ..». . 721 | ——tibial, anterior . . . 709 | —— posterior . . . 732, 735 tracheal, recurrent . 735 | ——trifacial . . . . 733 | ——trigeminus . . : 705 | ——trochlearis . . . 711 | ——tympanic. .. . 706 | ——tympano-lingual . . 712 | ——ulmar. ... . A ib, | —— vestibular. . ... 713 | ——Vidian . ... 766 Wrisberg, of . ; 712 | Nerve-tubes of spinal cord 709 | Nervous colline . 755 glands... ... «sip vam 750 | —— medulla 4, eo SR 774 sheath ,. 5. . -.ceuee 728 | ——system . 722 | —— pti comformation 728 | —— of Birds, .. . 724 tissue... .. . 733 | Neuralarch. . . ° . 753 | Neurilemma > =a ae 760,466: | Neurility . +2-.< spacuee 760 | Neuroglia . ‘. ib, | Nodule of Arantius . Z ib, | Nodus encephali 728 | Nomenclature . ot 774 | Non-medullated fibres he. 721 | Nostrils . . Le 722 framework d 727 functions . ° 716 | Nucleated nerve-fibres . 752 | Nuclei of corpus striatum . 758 of nerves , : . 734 735 | Obturator foramen. . . 755 | Occipito-atloid sinus . . 753 | Ocular membrane . . . 754 Sy. ee eek 751 | Csophageal groove . ‘ 775 | Csophagus . . od hs 771 OOUIP~E:. b.s Dt nee 771 form .34 773 | —— functions . 772 | —— relations 713 structure . | 746, 752 | Oken’s bodies ; 736 | Olfactor be atone 786 | ——ce : : 787 ails . . . 718 | —nerves. . . + 725 | Omasum.. 767 | ——structure . 3-3 poses Se a SERS i nek 2 OX. ere Gis . £ PROUT ho Pe CPE eee heer Ca ey ee ee Oe Mn me Yen wee en SO 8 BR or A, Be. pe Siete, e 2 6 Ue a ‘ a = ; Ore. ia | } = fete Shes 6 £4 . -i8t we Sa oe ee oe, ee eee H vet & S835 BEEBE , 4 Ee Be aw vac site enettt in < SE8S%E reg a ‘ ¥ « ¢26, @ de: 6 @y 6 Be see e es (ence _-_ ~~ a | oe eee - — — functions of . Svs SETUCEETS | —— soft — functions of Pes anserinus INDEX, PAGE . 382,389 | Palate, soft, muscles 383, 429 —— structure 382,389 | Palatine glands . . 894 | Palatummolle . . . . 899,915 | Palmararch . .. . < "S02 |) -Palpeire oY oS 711 | Palpebral sinuses 707 | Pampiniform plexus ib. | Pancreas - . 675 | —— development ; . 706 excretory apparatus : . 824 Se ae - . 675 | —— functions . 820, 824 | —— relations . 843 | —— situation 817,828 | ——structure . 839 | Pancreatic ring . . . 443 | Papilla cornica . . 876,923 | Papille . . . . 652, 653 of foot sre 5 of skin 326 of tongue ib. | —— calyciformes . 3828 | —— capitate : 328,329 | —— circumvallate 843 | —— filiformes . 879 | —— fossulate ib. | —— fungiformes ib, lenticulares . . 837 | Parieto-temporal confluents 842 | Parotid duct ; 16 gland 347 | Parovarium . 118 | Pathetici nerves . 16 | Pavilion of Fallopian tube . 6 | Pecklin’s glands . ; 876 | Pecquet, cistern of . ib. | Pectoral cavity . 839 | Pedunculi cerebelli . i. | —— cerebri 925 | Pelvis 872 difference in sexes 874,924 | —— in general . 874 | Penis eres 872 | Peptic glands : ‘ 873 | Perforans tendon, sheath of 876 | Pericardium. . 5 873 | —— muscle of . 874 | Perilymph . | Perimysium . 873 | Perineum 879 aponeuroses of 873,890 | Perineurium 890 | Periople. . 873 Perioplic ring Periorbita 663 | Periosteum . . «+ 703 | Peritoneum . . 332,356,359 | —— structure of 333, 356, 359, 360 | Perivascular canals . . . « + 834 | Perspiration . ; chin? ee ches abel ducts . 340, 357, 359, 360 | —— glands : ” 867 Pes hippocampi . Petit, canal of . Petrosal sinuses . Peyer's glands Phalanges . ‘ Pharyngeal arches . —-cecum .. development of —— disposition —form .. — functions . —— muscles —— relations structure . Phillips’s muscle Phrenic centre . Pia mater . . cranial spinal Pigment cells Fees: corpuscles 0 of horn ——granules . . Pigmentum nigrum Pillars of diaphragm —— of fornix, anterior posterior ofheart . . of inguinal canal . ofrumen . . —— of soft palate . anterior —— posterior . of tongue, anterior posterior Pineal gland Pisiform tubercle Pituitary fold of dura mater structure ‘of . od multiple simple. . Plantar arcade or arch . cushion . 3 — — bulbs of. structure of tunic, of . nerves . a —— reticulum . Pleure a structure . Pleuritis, effusion of Pleuro-peritoneal cavity Plexus, general anatomy —— anterior auricular —— —— mesenteric . —— brachial . —— bronchial . —— capillary, of lungs. —— coronary (venous) —— gastric a ttural . —— hypogastric lumbo-aortic . sacral —— lymphatic . —— mesenteric, anterior ——— posterior . —— myenteric . — a ; —— pelvic. . = TF, Pearyngeel — Kaaba venous . splenic subzygomatic . superficial cervical suprarenal . sympathetic ——tracheal . —— vaginal venous. Plice palmate . ; Pneumogastric lobule. Podophyllous tissue Pons Valorii . . Popliteal glands Portio dura . mollis . Porus opticus Pouches, guttural Poupart’s ligament . Preputial g 5 Preputium clitoridis Precervical nerve Precrural glands PREPARATION :—arteries wot ee Hite venous . —— —— dissection . —— —— injection —— arteries, anterior tibial — — aorta, en a — — axill ——— —— femo —— — head, of . . —— —— iliac, internal internal iliac popliteal . —— —— posterior tibial . — — pulmo —— — tibial, anterior . —— articulations . atlo-axoid posterior . chondro-sternal acy 28 " spngsaggazeai aa oat 2 ee} 2 4 aegiees E ry SEs EIS SESSELERZLELSRERILZESRSERE —t 7. -” - -— — ———— - metacarpo-p! I _——— occipito atloid . reps articulations, pnts — —— coxo-femoral . —— femoro-tibial . — — first ae — — humero-radial . — — hyoideal - tases, ‘first — — — second halangeal — muscles . . —— — abdominal region, inferior . —— — alveolo-labialis . . . —— — anterior brachial region pi — —— — crural region. . . a aa jon . . —— — brachial region, anterior é posterior . . eos ee Ee, eer $ — — — — superior — —— costal region wis ———-cruralregion . . . . — — — —— anterior. . . — — —— —— internal , — — —_ —_ posterior —— —— diaphragmatic region . — —— external as eae region . ee oitsjae te femoral region «Se : flexor, short, of fore-arm . — —— fore-arm, of Ovideal region on. ; _—— inferior abdominal region ° — — — cervical . —— —— — lumbar region : INDEX, 951 PAGR PAGE 141 | Preparation, muscles, internal ata 161 region «w+ we . 252 163 | —— labialis . . om BIT 156 | —— le - 297 144 | ———— lumbar region, inferior. . 211 139 | ——-—— masseteric region . . . 223 156 | ——-—— mastoido-humeralis. . . 196 157 | ——- —— medius, anterior . 222, 223 153 | ——-——-panniculus . . . - 186 137 | ——- —— scapular region, external 249 159 | —— —— —— in . 252 143 | ——-—— spinal region of back and 130 loins . . Z 203 168 | ——-—— sublumbar region « Si 138 | —— superior cervical , . 187 837 | ———— peg enraaty region . 223 755 | ——nasal cavities . . ot 4 460 | —— esophagus .... . 377 G20) | «== palate. ...u ss ats 332 819 | —— pancreas “ 419 705 | —— parotid gland . Fs 365 877 | —— pericardium ¢ 512 674. | —— pharynx . - « 372 817 | ——retina . : 824 781 | —— soft palate ‘ ; 340 503 | ——spinalcord . Aa 666 507 | ———splen*. . 2. «2 «© “se jers 419 799 stomach nO 385 877 | — submaxillary gland oS at he 367 400 sympathetic nervous urd 781 449 thoracic duct . ‘ 643 419 | ——tongue . 334 770 | ——tracheaa . . a ate 457 466 | —— urinary apparatus «Giese BE 633 veins . ane 599 367 | Prepuce. . ok) as sa. eee 330 oes, .. octane 184 | Preservation of muscles. wv: RE 239 | Primitive aorte . ore DS 218 | —— band of Remak - . 652 255 chorion Pe - «+ 896 283 eye-vesicles . . 3. 1s « 908 231 b me ye; fasciculus . . - . . . . 178 Te Te ee ee ee re) 255 | ——trace . : diya Lae 258 | Primordial kidneys . : o os O28 196 | Processes e cerebello ad testes o ate LORS 187 | Promontory ofear . . . . . 840,842 235 | Properties of nervous dane » eo 685 283 | Prostate gland . . é: live a: 864 i. | —— structure ae Sh = B 288 | Protoplam . .. . . 3 286 | Protu tia annularis . 675 245 | Protovertebra . . . 905, 911 249 | Protovertebral cavity «! ‘~ 06 828 | Pulmonary peer . ‘“ 521 283 | ——heart . - m 503 256 lobes . ‘ 466 261 lobules aye 468 280 opening of heart . 505 225 eura , 464 239 | —— tissue . 467 196 vesicles . . 468 211 | Puncta lachrymalia 834 952 Punctum cecum Pupil... ..% Pupillary membrane sphincter . Purkinje’s vesicle Pylorus . . Pyramidal eminence of os pedis Pyramids of the bulb —— Lowenberg’s . . : INDEX. PAGE . 824 | Salivary — development of 822 a ducts a . . . 824 | ——lobules . . ., ., 823 | Saphenaveins . . . . , 925 | Sarclemma ... . . ,. 388 | Sarcouselements . . . . 85 | Scala,auditive . . . . . 676 | ——collateral . : Racemose glands . 329, 339 3 Rachidiap bulb . ee Raphé of scrotum. 853 Receptaculum chyli 634 Recto-vesicle fold 860 Rectum . 413 —— attachment 413 development . 920 relations 413 structure. . 414 Recurrent sensibility 650 Reflex power. 657 Reil, band of . 678 Reissner, membrane of . 839 Remak, primitive band of . 652 Renal glomerules “ 488 —-pelvis. . . prey 6 Reseau admirable ik 590, 591, 593 Reservoir of thymus gland . 473 Respiratory ceeneens K 439 —— —— of Birds . 475 ————-of Mammifers . . 439 — nerves + Sg OS FOE Rete mirabile 593, 594, 631 ——mucosum. . «tte WF eo ophthalmicum, 595 testis . . 855 Reticular layer of the derma . 793 Reticulum 397 structure . ib. — pn aaa 613 Retina . . 824 Retrossal process of os pedis 85 Rhomboidal sinus 3 907 Ribs 4 4 67 Right auricle of heart . 505 ventricle ,, . . 503 _ Rima glottis ; 456 Ring, inguinal 242 pancreatic . . 427 —— umbilical, inferior 894 Vieussens, of . 506 Rings of trachea 468 Rivinian ducts . . . 369 Rolando, gelatinous substance of 670 Root of lungs . . ! 461, 466 Rosenmiiller, organ of. 806, 923 Rudimentary sinuses 606 Rumen ; 394 — structure of . 396 Sacculus ofear . 839 Sacral nerves 752 Sacrum. . 26 Salivary glands 364 —— tympani. 299% vestibuli ve ee proper . “bey en Schindylesis : : Schneiderian membrane structure of Schwann, white substance of Sclerotica . he a Sclerotic cleft Scrotum Scutiform cartilage . Sebaceous glands . . . Secondary dentine . . . . Segmentation of vitellus . . Semen Pe Semicircular anastomoses 7 band joi. 2-7 ae —ecanals. . . . .. ganglia —— valves Semilunar crest of pedal bone . fibro-cartilages ‘ Seminiferous tubes . Sensitivo-motor centre : Sensorial functions oh tee Septum auricularum ot @i \e 6.) anes lucidum . . SPREE —— pectiniforme . : ees OTOL 8 ss ventricularum ; Serous burse: 9. 3 Po Se membrane — stratum ofepiblast . . Veticle <2". Sige Sesamoid bones. . . Sheaths, arteriesof . . . —-hairof ..... —— lymphatic metacarpo-phalang —navicular. . geal ocular —— penis, of . —— perforans tendon, of —— Schwann, of . : Shell, eggiof <5. S52 4 membrane .». . . . Shoulder, bones of . Sigmoid valves . Simple follicles —glands . —— placenta Sinus ampullaceous ——. aortici — circularis iridis . >, &Pieh #3". oooh ek ether ess oj stacey espe eee Bee een. BSSSSeSar8SSSsesses 4 505, < > ~P a + i eet. fee ~ tt ¥ * 288 eo 1 Oe a 9 65)\0: 06) SO USSR: wT SG gegase 82 -_ & 4 Ole * denBSESESEERS y g--- Sss8s ST eee © bee i at 2 2 I D Pine 1 of —_ — development of —— —— functions of 5 INDEX, 953 PAGE PAGE 724 | Spinal cord, figure. . . . . . ob 85 | —— ——general view of. . . . 666 861 | — internal conformation . . 668 . . 486 ————structure . . . . 668,669 . 683, 907 | —— ——vyolume . .°. i: * « 668 »- .« 915 | — Weeut.s= 6 oe i ee 522 ——duramater . . . . . . 661 097: | —— arrow. ;> .. - . Ce Ow OE 522 —— nerves . eC ker ae 605 —— —— constitution . “ana RAT? WAY 606 | —— ——nerve-tubesof . . . . 671 ib. | WER Sas es; see th, | Spine, the,in general . . . . . 28 i. | Splanchnology . . . . . . . 326 i. | Spleen . . le Soca Smet gs wd. | attachment . . . . . - 429 i. | development . .° ... . . 9223 . | ——direction . . .°. . . . 428 447 a Mit a I SE REO RE E 608 | ——ffunctions . . . .. . . 481 606 | ——relatins . . . . . . . 488 am ORCI 8G. so Mo cee ae 446 —etrncture.: .° «' .' 5°. 4 “S28 447 MEOUAG = gd pare e Ser ee 448 | Splenic corpuscles . . . . . . 430 PO a et ice cal te ane See a ee 446 | Spongy portion of urethra. . . . 862 447 | Spontaneous voluntary movements . 657 ib. | Stapes ey et Meta - 845 td. Staphyline glands Seattte! F . 870, 371 532 | StarsofVerheyen . . . . . . 489 850 | Stenon’sduct . . . = . . . $867 486 | Stenson’sduct . . “ce Seek Stilling, dorsal a of SL Sy eR aes 456 | Stomach in Soli ce +e pce ib, | ——-—— deve oa) 2 9/ 20" ane 915 | ————dimensioss . . . . . 3886 522 | —— Ws? ww! : 5, Ue ee ee 7)|— functions . .°. . ¥ 898 792 | —— interior +: ee.) ae 797 | ——-——-ligaments . . -' an 792 | ———— muscular membrane PA 795 | ————-orifices . . . . .'. 888 796 | ——-———situation . . . .' . 886 — stractarg (.. ws — Carnivora. . ... . . 893 > 867 a Pig . . . . . . . . ; 1b. 815 | ——Ruminants ...... 372 | —— functions” . 9... Ge 836 | Subarachnoid fluid ata baci Subarytenoid sinus =. ” 807 Subcorneous integument . . . . 803 $28 | Subcutaneous region . . . . . 106 Subepiglotticsinus . . . . . 456 Subhepatic veins . . . . . . 423 246 | Sublingual crest . . . . =. « 834 856 g + + ns yo OR De 414 | Sublobular veins 424, 425 823 | Sublumber reservolt . . . . . 684 Submaxillar a” Se Ody OFa 663 | Subpodophyllous reticulum . . . 613 659 | Subsphenoidal confluents . . . . 608 666 Substantia gelatinsa . . . . . 670 668 |. ——ostoidea . . .. .. . 846 954 INDEX. PAGE Substantia perforata 692 | Tendons, extensor pedis Suburethral notch . 866 | —— external flexor of metacarpus Succus prostaticus . 864 | —— flexor, of metatarsus n Sudoriparous glands 794 | ————hok ... .. Sulci horizontalis ? 686 | ——gastrocnemii . . . . . Superior umbilicus er: 893 | —— tdorsal . . Suprarenal capsules . . 494 | —— large extensor of fore-arm m davsleuaiiat 495 lateral extensor of ic a form . 494 at emcee middle ” . . . —— —— functions 3992 495 | —— oblique flexor Pi ——-relations . . . , 494 | —— perforatus nd ge —-- situation ib, | ——perforans. .°. . 267 structure ih | ——prepubic . . . fe: 8 Suprasphenoidal appendage : 681 | Tentorium cerebelli sae Seeger, ligament of fetlock . . 154 | Tentacula . . ae penis . . . 865,866,872 | Terminal genital corpuscles Paar? -_— sheath ose ta A Oe motor plate sofa ———uterus . . ... . 877 vesselé. . . |... Sylvius, fissure of -. . . . . 691,692 | Testaceous membrane . . . . Sympathetic nervous system . « 781 | Testes cerebelli . . att § — functions . 789 muliebres . ooh + structure . ih, | ——tubercula. . . . . . Symphyses . eee 129 | Testicles . »' Jo jane Synarthroses . 128 attachment of . . . . classification of 129 | ——descentof . ... . Synovia. . . 127 development of wi Synovial capsules 126 | ——ectopie of . 5 Me fossa 123 envelopes of . . om fringes 127 external conformation . . Syntonine . 181 | ——functionof . . a> ite Systole of heart 513 structure of site Testicular cord . . Par Tactile corpuscles . . 703 | Thalami optici . . ois Tenia hippocampi . . . . . . 695 | Thebesius, valve of . é ogee semicircularis . . . . 680,695 | Thecavertebralis . . . . . Fat Fo apie 0. "ey, te. 29%. | Dhiernésse’s:muscle ~ | sae Tapetum ‘ . . . . . 820,822 | Third ventricle ofbrain . . . Tarin, valves deat: Nee 687,689 | Thoracic aorta . stir ghia Tarsal sheath : . 805.) ——eavity. . . . 3 aly Tarsi 831 uct..." os. ee Tarsus . 102 | —— affluents of . is ones apparatus of 813 | —— —— course of ow Tea’ ‘ 884 | —— extent .. . are Teeth etd 344 | ———— origin ror —— characters of eee ew 86 | ——— termination a —— development of . . . 347,921 | ——-——varieties in . sialon —— disposition of «spt BE’) Phorax. x : INDEX. -) PAGE Pears sk. 334, 357, 359, 360 | Unipolar nerve-cells — . —— conformation - - + » . S34 | Uniting tube of kidney. . —— development o 920 | Unstriped muscular fibres 5 —— functions of . oes os ee Drache. ‘ — muscles of. . Jive. a S861 Draters. . — pillars of 335 | —— direction —— situation of 334 form . ——structureof . . 335 origin. . er. - . 335 | ——structure . —— of cerebellum 689 | —— termination Torcular Herophili 606 | Urethra . of spleen . 429 | —— male, of — Sa 855 | ———— course Trachea . . 457 | ———— interior . — course. . . | ——+—— relations. —— development 918 | —— structure —-form .. 457 | —— female, of . —— relations i. | Urethral ridge . . . —— structure . 458 7 sinus . erie Trace, primitive . : 892 rinary apparatus ; Tracheal glands. . 459 | Uro-genital sinus Tractus longitudinalis 693 | Uterine glands ——opticus ... 707 | —— — Z 8 ——respiratorius . . 704 | —— unctions of . Transverse aes ar 606 | ———— structure T . oe 504 | Uterus . Teitechl werve ee cae 710 attachment Trigeminii . . . ; ib. development Trigonum vesice . . . 493 form : ; ; system . . 781 functions . SS 128 | —— interior Trochlearis nerve . 709 | —— masculine . Tuber annulare . 677 | —— situation —cinerium . . 681 structure . Tubercula nates. 679 | Utricular glands —quadrigemina. . . ib. | Utriculus of ear —testss ... ib. prostatic . . Tuberculum Loweri 506 | Uvula of cerebellum glands . 322 Tubuli seminiferi 854 | Vagina 4 ——uriniferi . 487 | —— functions . . = Tuft of chin. . 331 | —— internal conformation Tunic of plantar cushion ach ny O08 situation . . Tunica a a) ore - structure . —— ovary ey aginal bulb —-- eae testicle ‘ . 854 | ——sheath. . — . 852 | —— synovial membrane a Diediens - 821 | Valsalva, sinus of . —vaginalis . . 852 | Valves, Bauhin, of . — — communis . Pato —— — reflexa ib, | —— iliv-cecal . ee oagyra testis 855 Kerking, of 841 | —— lymphatic. 839 | —-— meatus urinarius . 840 | ——mitral. . wate follicles 365 | —— Renault, of —— semicircular Umbilical cord : 895,900 | —— sigmoid —— arteries 900 | —— Tarin, of P — — - 381 Thebesius, of . — . . « « 900 | —— tricuspid —— vesicle " 894, 895,899 | ——veins,of . . Umbilicus, superior . . « . 893 | —— Vieussens, of . 955 PAGE 653 488 | 327, 328 | 894, 897 490 597 . 675, 679 956 Valves, vulvo-vaginal Valvule conniventes Varolii, pons. Vasa afferentia . efferentia . —— inferentia . — recta ——vasorum . . . of veins. . vorticosa . . Vascular blood glands 5 Vas deferens structure of. Vegetative life, nerves of Veins:—definition .. ‘ external conformation general considerations injection of —— internal conformation structure . abdominal, subcutaneous , alveolar angular of eye auricular, anterior posterior . 4 axillary — basilic . “ —— basium vertebrarium —— buccal . —- cecal . — cardiac . —— cardinal, anterior . posterior cephalic : central of foot of retina cervical, superior . circumflex of foot — —— collateral of cannon, external internal coronary, great small of foot dental, inferior superior . diaphragmatic. —— gastric, anterior . —- brerttcalpee de left ee | —— glosso-facial — hemorrhoidal | —— humeral —— iliac, common . external internal . —— ilio-cecal . innominate. —— interlobular of liver r interosseous . ¥ —— intralobular of liver : INDEX. PAGE ' * . 887 | Veins, intra-osseous of foot. . .. . 402 — jugular . . . . . . 675, 677 — Tabial 4 oe eee . 632 Lert pes . . . . . 632, 855 | —— mammary, internal». 632 | —— maxillary, external . . . 855 | ———— internal. . . . . 520 | —— maxillo-muscular . ot; Ghee 598 | —— median spinal . ae 821 | —— subcutaneous... 330 | —— mesenteric, great. . . . « 859 Lem small . . . . an . 860 | —— meseraic, anterior, . . . « 652 | ——+—posterior . . . . . 596 metacarpal .. 4) jf) ee tb. metatarsal . . . : . . ¥ ib. ne deep . o = oh ae 599 | —— external , oe re 597 SS aa internal . . . . . 599 | ——nasal . . . Se Lhe” 625 | —— occipital ~ Aa 602 | —— omphalo-mesenteric > 2 =a ib. | ——pelvi-crural . . . . . « 604 —a plat . . . . . ; 602 | ——podophyllous. . . .. . 609 | —— popliteal o* Je eee 611 portal. . arate 599 arn oe internal . . . . * wu ib, | —— thoracic... hue 614 subhepatic ‘| gh sane 605 sublingual : ee 603 subscapular ee a sp BET subzygomatic .. ee SEAS 612, 625 superficial temporal . . . 601,6 600 suprahepatic . . | oS a 623 temporal, deep . | ae 608 | —— superficial - . 601, 6 621 testicular . o. +e ie. On 621 | —— Thebesii . » oe w. | —— thoracic, internal , . oe 602 | ——thyroid . . .° » (Sue 621 | —— tibial, anterior . 610 |}. —— posterior .. a ee 622 last: Soha ey 623 | —— umbilical . in a 622 un ; re: 620 | —— pre tg . Pe 603 | —— vertebral . 500, 9: 423 | —— eava, anterior ; . 612 —— posterior a 424 | Velum interpositum ; 691, 6 INDEX, PAGE 340 | Vidian canal . . 696 | —— fissure . 803,804 | —— nerve . . . . 600 | Vieussens, centrum ovale of - . + 7, | Villi, intestinal cas « GOO) Villbsitiog . . 617 | Villo-papille of foot . 691,696 | Villous bop ot of foot . . 617 | Vitellus 598 | Vitreous body . 821 humour 682, "683, 692,693 | Viscera . . Wiles 688 | Visceral pleura . . . 693 | Vision, apparatus of Stk 693 | Vitelline duct Oe Ate 682 globules » os» 683°} Vocal:cords.. jis kes" CS2! superior —— —— thalami optic ao. OMe Voluntary movements . —ofheart . . «te ae 800...) Valve — of ‘ 456 cavity ofa. Ventricular arachnoid 694 external eens of —massofheart. . . . . . 500 structure . Vermiform appendix . . . 418 | Vulva of brain . —— processes of cerebellum . . . 686 Vulve, labia —— ———-anterior . . .. —_ —_ — mor 82 | Wall of hoof 7 Vermis of aus 3. 5° SST angle of CE te ge dS structure of _ ——characterscommonto . . . 19 | Wharton’s duct ————proprto ..... 21 gelatine of —development . . . . . 20,911 | White line of hoof . —structure. . . . . . . 20 | ——substance of Schwann Vertebralcolumn . ..... 18 | — spinal cord . . 3 —— — development of. . . . 911 longitudinal fibres of brain — constitution of skeleton . . . 118 | —— transverse et —lamine.. 905 | Wilson’s muscle — . Vertebro-costal channels 462 | Winepress of Herophilus Veru montanum 861 | Winslow, foramen of Vesicle, serous . 893 | Wirsung, duct of ‘ —— lical . 899 | Wolffian bodies . Vesicles, Graafian . 873 | Wrisberg, nerve of Vesivala athe 8 Xiphoid appendage of sternum ; —— seminalis tertia 61 i.Vekan . Vesiculz seminales 860 ) Yolk of egg . 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Pg sf Anderson (McC.) on Eczema . 19 McC.) on Parasitic Affec- tions . . . . 19 Arnott on Cancer. . Aveling’s English Midwives . - 14 Balfour’s Diseases of the Heart ae Barclay’s Medical Diagnosis ° Barker’s Puerperal Diseases . Barnes’ Obstetric Operations . - 14 — Diseasesof Women . Basham on Renal Diseases . — on Diseases of the Kidneys Beale on Kidney Diseases . 8 Bellamy’s Guide to Surgical Anatomy 10 Bennet’s Winter and Spring on the Mediterranean . . 16 — Pulmonary Consumption - 16 — Nutrition . 18 Bennett (J. R.) on Cancerous Growths 19 Bigg’s Orthopraxy . . Pe Black on the Urinary Organs é . 8 — on Bright’s Disease ; a Braune’s Topographical Anatomy . 11 Brodhurst’s Orthopedic Surgery . 6 Bryant’s Practice of Surgery. 4. Bucknill and Tuke’s Peychological Medicine . . 21 Burdett’s Cottage Hospital . . 14 Buzzard on Syphilitic Nervous Affee- tions. - 9 Carpenter’s Human Physiology ~ 20 Carter on Mycetoma - 20 Cauty on Diseases of the Skin . - 20 Chapman on Neuralgia . . 18 Charteris’ Practice of Medicine -1l Clark’s Outlines of Surgery . «. 4 — Surgical Diagnosis 5 Clay’s Obstetric Surgery . . - 18 Cobbold on Worms . ‘a . . 20 Coles’ Dental Mechanics . . . 23 Cooper’s Surgical Dictionary . » 4 Cormack’s Clinical Studies 4 . 12 Cottle’s Hair in Health and Disease . 20 Coulson on Syphilis . F . 9 — on Stone in the Bladder. 9 Cullingworth’s Nurse’s Companion . 14 Curling’s Diseases of the Rectum . 7 . 4 TL) Dalby on the Ear Dalton’s Human | Physiology Day on Children’s Diseases — on Headaches. , De Valcourt on Cannes . 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F : 20 Glenn’s Laws affecting Medical Men. 20° Godlee’s Atlas of Human Anatomy . 11 Gordon on Fractures ; ‘ - OM Habershon on Diseases of the Liver . 17 — on Diseases of the Stomach 17 — onthePneumogastric Nerve 17 Hancock’s Surgery of Foot and Ankle Harris on Lithotomy : . : Hayden on the Heart . . Heath’s Minor Surgeryand Ban — Diseases and Lnjaries eae — Operative Surgery . — Practical Anatomy ° Higgens’ Ophthalmic Practice . Holden’s Landmarks ’ Holt on Stricture of the Urethra Hood on Gout, Rheumatism, &e. Hooper’s Physician’s Vade-Mecum Horton’s Tropical Diseases. {utchinson’s Clinical Surgery . . Huth’s Marriage of Near Kin . Ireland’s Idiocy and Imbecility Jones (C. H.) and Sieveking’s Patho- . «- > + he Ss 37a» 6. i's sobbbitased ae ~ an logical Anatomy . . L — (C. H.) on Functional Nervous Disorders . - 7 7 i INDEX 8 Jones (Wharton) Ophthalmic Medi" | Smith (W. R.) Nursin mid n = m . . g . cine and Surgery . . 23 | Spender’s Bath Waters - 16 Jordan’s Surgical Inflammations . 6 _ 8 ical _— a - Kennion’s arrogate Lawson on ca, &e. * 18 Lee (H.) Practical Pathology a is . on Syphilis . . . 8 Leared on Imperfect Digestion. . 18 Liebreich’s ao of ny os on F Mecdenald’s ae boring of Water . 22 Mackenzie on Growths in the Larynx 15 Macnamara on Diseases of the Eye . 22 Madden’s Health Resorts . - 16 Marsden on certain Forms of Cancer 19 Mann on Harelip ae Cleft Palate . , aunder’s Operative Surgery . ° 3 of Arteries . ° f. 's Medical Vocabulary . . Mayne ’s System of Nerves . . 18 Moore’s Family Medicine for India . 17 Parkes’ Manual of Practical Hygiene 21 Parkin’s Epidemiology . . . 23 Pavy on Food and Dietetics - 18 Peacock’s Valvular Disease . .15 Phillips’ Materia Medica. . .12 Pirrie’s Surgery a wa? ret Ramsbotham’s Obstetrics . - 13 Uses of Electricity - 22 Roberts’ Practice of Midwif . 18 Roussel’s Transfusion of Blood. . 5 Ronth’s Infant Feeding . - 12 Roy’s Burdwan Fever . -17 Royle and Harley’s Materia Medica . 12 Rutherford’s Practical Histology . 10 Sabben and Browne’s ~ ge ies of Law and Lunacy . ~ Salts’ Medico-Electri¢ A —— Sanderson’s Physiological andbook . "9 Sansom’s Diseases of the Heart . 16 Savage on the Female Pelvic Organs 5 Savory’s Domestic Medicine. - “ Scliroeder’s Manual of Mi nual of wifery "3 Semple on the Heart . 15 Sewill’s Dental Anatomy. . . . 23 Shapter’s Diseases of the Heart . 16 Shaw’s Medical Remembrancer - 12 on Madness - , - 21 Sibson’s Medical Anatomy. . Sieveking’s Life Assurance ‘ - 21 Smith ) ise Diseases of Children — Smith (Hens) Surgery of the Rectum Smith tanh oapera ei . 13 Smith (J.) Dental Anatomy . . 23 Steiner’s Diseases of Children . - 12 Stowe’s Toxicological Chart . Sullivan’s Tropical Diseases . Swain’s Surgical) Emergencies. . 5 Swayne’s Obstetric Aphorisms . - 13 Taft’s Operative Dentistry . - 23 Tait’s Hospital Mortali . 14 Taylor’s Principles of edical Juris- prudence . — Manual of Medical Juris- prudence . - 20 — Poisons in relation to Medical Jurisprudence . mM - 20 Thompson’s Stricture of Urethra 7 _ Practical Lithotomy and Lithotrity 7 —_ Diseases of the Prostate . . _ Calculous Disease . ° Thornton on Tracheotomy ® . 16° Thorowgood on Asthma . . - 16 — on Materia Medica - 12 Thudichum’s Pathology of Urine . 9 Tibbits’ Medical Electricity . . 22 — Mapof Motor Points . - 22 Tilt’s Uterine Therapeutics - 18 — Change of Life 4 . 13 — HealthinIndia . -17 Tomes’ (C. 8.) Dental Anatomy - 23 (J. and C.S.) Dental Surgery 23 Tufnell’s Internal Aneurism Tuke on the Influence of the Mind upon the Body - 21 Van Buren on Dhdviices of the Genito- Urinary Organs. ° 9 Veitch’s Handbook for Nurses . ‘ 14 Virchow’s Post-mortem Examinations 10 Wagstaffe’s Human Osteology - 10 Walton’s Diseases of the Eye Ward on Affections of the Liver a f Waring’s Practical Therapeutics . 12 — Bazaar Medicines of India. 17 Waters on Diseases of the Chest - 16 Wells (Soelberg) on Diseases of the Eye 23 — Long, Short, and Weak Sight. 23 Wells eon on Diseases of the es ° - 13 Wife’s Domain “ : -14 Wilks’ Pathological ‘Anatomy ; - 10 Wilson’s (E.) Anatomist’s Vade- Mecum . . * ll — Diseases of the Skin. . 19 — Lectures on Ekzema . 19 — Lectures on Dermatology . 19 Wilson’s (G.) Handbook of Hygiene. 21 Woodman & Tidy’s Forensic Medicine 21 4 CATALOGUE OF RECENT WORKS THE PRACTICE OF SURGERY : a Manual by THomAs Bryant, F.R.C.S., Surgeon to Guy’s Hospital. Second Edition, 2 vols., crown 8vo, with 559 Engravings, 25s. cis76y THE PRINCIPLES AND PRACTICE OF SURGERY, by Witu1aM Prreiz, F.R.S.E., Professor of Surgery in the University” of Aberdeen. Third Edition, 8vo, with 490 Engravings, 28s. [1873 A SYSTEM OF PRACTICAL SURGERY, by Sir Witt1am Ferevsson, Bart., F.R.C.S8., F.R.S. Fifth Edition, 8vo, with 463 Engravings, 21s.. (1870) OPERATIVE SURGERY, by C. F. Maunper, F.R.C.S., Surgeon to the London Hospital, for- merly Demonstrator of Anatomy at Guy’s Hospital. Second Edition, post 8vo, with 164 Engravings, 6s. 1872) BY THE SAME AUTHOR. SURGERY OF THE ARTERIES: Lettsomian Lectures for 1875, on Aneurisms, Wounds, Hamorrhages,. &c. Post 8vo, with 18 Engravings, 5s. (1875) THE SURGEON’S VADE-MECUM, by Rosert Druitt. Hleventh Edition, fcap. 8vo, with numerous En- gravings. (In the press.) THE SCIENCE AND PRACTICE OF SURGERY: a complete System and Textbook by F. J. Gant, F.R.C.S., Senior Sur- geon tothe Royal Free Hospital. 8vo, with 470 Engravings, 24s. (1871) OUTLINES OF SURGERY AND SURGICAL PATHOLOGY, including the Diagnosis and Treatment of Obscure and Urgent ; Cases, and the Surgical Anatomy of some Important Structures and Regions, by F. Le Gros Cxiark, F.R.S., Consulting Surgeon to St. > Thomas’s Hospital. Second Edition, Revised and Expanded by the ; Author, assisted by W. W. Waastarre, F.R.C.S., Assistant-Surgeon — to, and Lecturer on Anatomy at, St. Thomas’s Hospital. 8vo, 10s. 6d. } CLINICAL AND PATHOLOGICAL OBSERVATIONS IN INDIA, by Sir J. Favrer, K.O.8.1., M.D., F.R.O.P. Lond., F.R.S.E., Honorary Physician to the Queen. 8vo, with Engravings, 20s. 11873} DICTIONARY OF PRACTICAL SURGERY Fs, and Encyclopedia of Surgical Science, by SamugrL Cooper. New Edition, brought down to the present Time by Samurn A. Lanz, Consulting Surgeon to St. Mary’s and to the Lock Hospitals; assisted by various Eminent Surgeons. 2 vols, 8vo, 50s. (1861 and;1872), a I PUBLISHED BY J. AND A. OHUROHILL 5 SURGICAL EMERGENCIES together with the Emergencies attendant on Parturition and the Treatment of Poisoning: a Manual for the use of General Practi- tioners, by Win11aM P. Swarn, F.R.C.S., Surgeon to the Royal Albert Hospital, Devonport. Second Edition, post 8vo, with 104 Engravings, 6s. 6d. [1876] TRANSFUSION OF HUMAN BLOOD: with Table of 50 cases, by Dr. Rousset, of Geneva. Translated by Ciaupe Guinness, B.A. With a Preface by Siz James Pacer, Bart. Crown 8vo, 2s. 6d. (1877) ILLUSTRATIONS OF CLINICAL SURGERY, consisting of Coloured Plates, Photographs, Woodcuts, Diagrams, &c., illustrating Surgical Diseases, Symptoms and Accidents; also Opera- tions and other methods of Treatment. By JonaTHan HuTcHINson, F.R.C.S., Senior Surgeon to the London Hospital. In Quarterly Fasciculi. Fasc. I to TX already issued. 6s. 6d. each. [1876-7] PRINCIPLES OF SURGICAL DIAGNOSIS especially in Relation to Shock and Visceral Lesions, by F. Lz Gros Cuark, F.R.C.S., Consulting Surgeon to St. Thomas’s Hospital. 8vo, 10s. 6d. [1870] ; MINOR SURGERY AND BANDAGING: a Manual for the Use of House-Surgeons, Dressers, and Junior Practitioners, by CHRIsTOPHER Hearn, #.R.C.S., Surgeon to Uni- versity College Hospital, and Holme Professor of Surgery in University College. Fifth Edition, fcap 8vo, with 86 Engravings, 5s. 6d. (1875] BY THE SAME AUTHOR, INJURIES AND DISEASES OF THE JAWS: JACKSONIAN Prize Essay. Second Edition, 8vo, with 164 Engrav- ings, 12s. (1872) ‘ BY THE SAME AUTHOR. A COURSE OF OPERATIVE SURGERY: with 20 Plates drawn from Nature by M. Liverixi, and coloured by hand under his direction. Large 8vo. 40s. (1877) HARE-LIP AND CLEFT PALATE, ‘by Francis Mason, F.R.O.8., Surgeon and Lecturer on Anatomy at St. Thomas’s Hospital. With 66 Engravings, 8vo, 6s. 1877] THE FEMALE PELVIC ORGANS, their Surgery, Surgical Pathology, and Surgical Anatomy, in a Series of Coloured Plates taken from Nature: with Commentaries, Notes, and Cases, by Henry Savace, M.D. Lond., F.R.C.S., Consulting Officer of the Samaritan Free Hospital. Third Edition, 4to, £1 lis. (1875) 6 CATALOGUE OF RECENT WORKS FRACTURES OF THE LIMBS and their Treatment, by J. Sampson GamGeEn, Surgeon to the Queen’s Hospital, Birmingham. 8vo, with Plates, 10s. 6d. (1871) FRACTURES OF THE LOWER END OF THE RADIUS, Fractures of the Clavicle, and on the Reduction of the Recent Inward Dislocations of the Shoulder Joint. By ALexanpER Gorpon, M.D., Professor of Surgery in Queen’s College, Belfast. With Engravings, 8vo, 5s. (1876) DISEASES AND INJURIES OF THE BAR, by W. B. Daxsy, F.R.C.8., M.B., Aural Surgeon and Lecturer on Aural Surgery at St. George’s Hospital. Crown 8vo, with 21 Engray- ings, 6s. 6d, (1873) AURAL CATARRH; or, the Commonest Forms of Deafness, and their Cure, by PeTER ALLEN, M.D., F.R.C.S.E., late Aural Surgeon to St. Mary’s Hospital. Second Edition, crown 8vo, with Engravings, 8s. 6d. (1874) CLUBFOOT : its Causes, Pathology, and Treatment; being the Jacksonian Prize Essay by Wm. Apams, F.R.C.S., Surgeon to the Great Northern Hos- pital. Second Edition, 8vo, with 106 Engravings and 6 Lithographic Plates, 15s. (1873) ORTHO PASDIC SURGERY : Lectures delivered at St. George’s Hospital, by Bernarp EH. Brop- HURST, F.R.C.S., Surgeon to the Royal Orthopedic Hospital. Second Edition, 8vo, with Engravings, 12s. 6d. (1876) OPERATIVE SURGERY OF THE FOOT AND ANKLE, by Henry Hancock, F.R.C.S., Consulting Surgeon to Oharing Cross Hospital. 8vo, with Engravings, lds. [1878] ORTHOP Z DIC SURGERY: and Diseases of the Joints. Lectures by Lewis A. Sayrz, M.D., Professor of Orthopedic Surgery, Fractures and Dislocations, and Clinical Surgery, in Bellevue Hospital Medical College, New York. With 274 Wood Engravings, 8vo, 20s. (1876) THE TREATMENT OF SURGICAL INFLAMMATIONS by a New Method, which greatly shortens their Duration, by FURNEAUX JORDAN, F.R.C.8., Professor of Surgery in Queen’s College, Birming- ham. 8vo, with emg 7s. 6d. [1870] ¥ THE SAME AUTHOR, SURGICAL INQUIRIES. With numerous Lithographic Plates. 8vo, 5s. (1878) ORTHOPRAXY : the Mechanical Treatment of Deformities, Debilities, and Deficiencies of the Human Frame, by H. HeatHer Biaa, Associate of the Insti- tute of Civil Engineers. Third Edition, with 319 Engravings, 8yvo, 15s. (18773 PUBLISHED BY J. AND A. CHURCHILL 7 INTERNAL ANEURISM: Its Successful Treatment by Consolidation of the Contents of the Sac. By T. Jourrre Turnet, F.R.C.S.1., President of the Royal College of Surgeons in Ireland. With Coloured Plates. Second Edition, royal 8vo, 5s. (1875) DISEASES OF THE RECTUM, by Tuomas B. Cur tina, F.R.S., Consulting Surgeon to the London Hospital. Fourth Edition, Revised, 8vo, 7s. 6d. [1876] ‘STRICTURE OF THE URETHRA and Urinary Fistule; their Pathology and Treatment: Jacksonian Prize Essay by Sir Henry THompson, F.R.OC.S., Emeritus Professor of Surgery to University College, Third Edition, 8vo, with Plates, 10s. [1869] BY THE SAME AUTHOR, PRACTICAL LITHOTOMY AND LITHOTRITY ; or, An Inquiry into the best Modes of removing Stone from the Bladder. Second Edition, 8vo, with numerous Engravings. 10s, 871] ALSO, DISEASES OF THE URINARY ORGANS: (Clinical Lectures). Fourth Edition, 8vo, with 2 Plates and 59 Engravings, 12s. 11876) ALSO, DISEASES OF THE PROSTATE: their Pathology and Treatment. Fourth Edition, 8vo, with numerous Plates, 10s. [1873] ALSO, THE PREVENTIVE TREATMENT OF CALCULOUS DISEASE and the Use of Solvent Remedies. Second Edition, feap. 8vo, 2s. 6d. 87 STRICTURE OF THE URETHRA and its Immediate Treatment, by Barnarp Hott, F.R.CS., Consulting Surgeon to the Westminster Hospital. Third Edition, 8vo, 6s. (1868) LITHOTOMY AND EXTRAOTION OF STONE from the Bladder, Urethra, and Prostate of the Male, and from the Bladder of the Female, by W. Pouerr Harris, M.D., Surgeon-Major H.M. Bengal Medical Service. With Engravings, 8vo, 10s. 6d. 1876] FISTULA, HA MORRHOIDS, PAINFUL ULCER, Stricture, Prolapsus, and other Diseases of the Rectum: their Diagnosis and Treatment, by Wm. ALLINGHAM, F.R.C.S., Surgeon to St. Mark’s Hospital for Fistula, Xc., late Surgeon to the Great Northern Hospital, Second Edition, 8vo, 7s. 12872] 8 CATALOGUE OF RECENT WORKS THE SURGERY OF THE RECTUM: Lettsomian Lectures by Hunry Siru, F.R.C.S., Professor of Surgery in King’s College, Surgeon to King’s College Hospital. Fourth Edition, feap. 8vo, 5s. (1876) THE URINE AND ITS DERANGEMENTS, with the Application of Physiological Chemistry to the Diagnosis and Treatment of Constitutional as well as Local Diseases. Lectures by GrorcE Hartey, M.D., F.RS., F.R.C.P., formerly Professor in in University College. Post 8vo, 9s. a KIDNEY DISEASES, URINARY DEPOSITS, and Calculous Disorders by LionetS. Bratz, M.B., F.R.S., F.R.C. P, Physician to King’s College Hospital. Third Edition, 8vo, with 70 Plates, 25s. [1868] DISEASES OF THE BLADDER, Prostate Gland and Urethra, including a practical view of Urinary — Diseases, Deposits and Calculi, by F. J. Gant, F.R.0.8., Senior Sur- geon to the Royal Free Hospital. Fourth Edition, crown 8vo, with Engravings, 10s. 6d. 1876] RENAL DISEASES : a Clinical Guide to their Diagnosis and Treatment by W. R. BAsHAM, M.D., F.R.C.P., late Senior Physician to the Westminster Hospital. Post 8vo, 7s. [1870] BY THE SAME AUTHOR, THE DIAGNOSIS OF DISEASES OF THE KIDNEYS, with Aids thereto. 8vo, with 10 Plates, 5s. [1872] THH REPRODUCTIVE ORGANS in Childhood, Youth, Adult Age, and Advanced Life (Functions and Disorders of), considered in their Physiological, Social, and Moral Relations, by Wixt1am Acton, M.R.0.8. Sixth Edition, 8vo, 12s. : (1875) URINARY AND REPRODUCTIVE ORGANS: their Functional Diseases, by D. CampsBett Brack, M.D., L.R.C.8. Edin. Second Edition. 8vo, 10s. 6d. [1876] BY THE SAME AUTHOR, LECTURES ON BRIGHT’S DISEASE, delivered at the Royal Infirmary of Glasgow. 8vo, with 20 Engray- ings, 6s. 6d. (1875) PRACTICAL PATHOLOGY : ° containing Lectures on Suppurative Fever, Diseases of the Veins, Hemorrhoidal Tumours, Diseases of the Rectum, Syphilis, Gonor- rheal Ophthalmia, &c., by Henry Lex, F.R.O.S., Surgeon to St.George’s Hospital. Third Edition, in 2 vols. 8vo, 10s, each. (1870) BY THE SAME AUTHOR, LECTURES ON SYPHILIS, and on some forms of Local Disease, affecting principally the Organs of Generation. With Engravings, 8vo, 10s. (1875) 7 a PUBLISHED BY J. AND A. CHURCHILL 9 PATHOLOGY OF THE URINE, including a Complete Guide to its Analysis, by J. L. W. Taupicuum, M.D. Second Edition, rewritten and enlarged, with Engravings, 8vo, lis. 01877] ‘“GENITO-URINARY ORGANS, INCLUDING SYPHILIS: A Practical Treatise on their Surgical Diseases, designed as a Manual for Students and Practitioners, by W. H. Van Buren, M.D., Pro- fessor of the Principles of Surgery in Bellevue Hospital Medical Col- lege, New York, and E. L. Keyxs, M.D., Professor of Dermatology in Bellevue Hospital Medical College, New York. Royal 8vo, with 140 Engravings, 21s. [1874] SYPHILIS : A Treatise by WattER J. Coutson, F.R.C.S., Surgeon to the Lock Hospital. 8vo, 10s. [1869] BY THE SAME AUTHOR, STONE IN THE BLADDER: Its Prevention, Early Symptoms, and ivonteient by Lithotrity. S8vo, 6s. (1868) SYPHILITIC NERVOUS AFFEOTIONS: Their Clinical Aspects, by Toomas Buzzarp, M.D., F.R.C.P. Lond., Physician to the National Hospital for Paralysis and Epilepsy. Post 8vo, 5s. [1874] ‘HISTOLOGY AND HISTO-CHEMISTRY OF MAN: A Treatise on the Elements of Composition and Structure of the Human Body, by Hernricu Frey, Professor of Medicine in Zurich. Translated from the Fourth German Edition by ArtHur E. J. Barker, Assistant-Surgeon to University College Hospital. And Revised by the Author. 8vo, with 608 Engravings, 21s. (1874) ‘HUMAN PHYSIOLOGY: A Treatise designed for the Use of Students and Practitionsns, of Medicine, by Joun C. Datton, M.D., Professor of Physiology and Hygiene in the College of Physicians and Surgeons, New York. Sixth Edition, royal 8vo, with 316 Engravings, 20s. (1876) -HANDBOOK FOR THE PHYSIOLOGICAL LABORATORY, by E. Kier, M.D.,F.R.S., Assistant Professor in the Pathological Labo- ratory of the Brown Institution, London; J. Burpon-SanprErson, M_D., F.R.S., Professor of Practical Physiology in University College, London; Micnart Foster, M.D., F.R.S., Prelector of Physiology in Trinity College, Cambridge; and T. Lauper Brunton, M_D., D.Sc., Lecturer on Materia Medica at St. Bartholomew's Hospital ; edited by J. Burpon-SANDERSON. 8vo, with 123 Plates, 24s. (1878) § 10 CATALOGUE OF RECENT WORKS PRINCIPLES OF HUMAN PHYSIOLOGY, by W. B. Carpenter, C.B., M.D., F.R.S. Eighth Edition by pate Power, M.B., F.R.C.S,, Examiner in Natural Science, University of Oxford, and in Natural Science and Medicine, University of Cambridge. 8vo, with 3 Steel Plates and 371 Engravings, 31s. 6d. (1876) PRACTICAL HISTOLOGY : By Witt1am RutHeEerRForD, M.D., Professor of the Institutes of Medicine in the University of Edinburgh. Second Edition, with 63 Engravings. Crown 8vo (with additional leaves for notes), 6s. THE MARRIAGE OF NEAR KIN, Pate Considered with respect to the Laws of Nations, Results of Experience, and the Teachings of Biology, by ALFRED H. Hutu. 8vo, 14s. 1875) STUDENTS’ GUIDE TO HUMAN OSTEOLOGY, By Witt1am Warwick WaastTaFrFreE, F.R.C.S., Assistant-Surgeon — and Lecturer on Anatomy, St. Thomas’s Hospital. With 23 Plates and 66 Engravings. Feap. 8vo, 10s. 6d. (1875) LANDMARKS, MEDICAL AND SURGICAL, By Luruer Houpen, F.R.C.8., Surgeon to St. Bartholomew’s Hospital. Second Edition, 8vo. {In the Press} PATHOLOGICAL ANATOMY : Lectures by Samuet Wiuxs, M.D., F.R.S., Physician to, and Lec- turer on Medicine at, Guy’s Hospital; and Waurer Moxon, M.D., F.R.C.P., Physician to, and Lecturer on Materia Medica at, Guy’s Hospital. Second Edition, 8vo, with Plates, 18s. [1875] PATHOLOGICAL ANATOMY : A Manual by OC. Hanprie~p Jones, M.B., F.R.S., Physician to St. Mary’s Hospital, and Epwarp H. Srievexrine,. M.D., F.R.C.P., Physician to St. Mary’s Hospital. Edited by J. F. Paynz, M.D., F.R.C.P., Assistant Physician and Lecturer on General Pathology at St. Thomas’s Hospital. Second Edition, crown 8vo, with 195. Engravings, 16s. (1875) POST-MORTEM EXAMINATIONS: a Description and Explanation of the Method of Performing them, with especial Reference to Medico-Legal Practice. By Professor RupoueH VircuHow, of Berlin. Feap 8vo, 2s. 6d. [1876] STUDENT'S GUIDE TO SURGICAL ANATOMY: a Text-book for the Pass Examination, by HE. Brttamy, F.R.CS., Senior Assistant-Surgeon and Lecturer on Anatomy at Charing Cross Hospital. Feap 8vo, with 50 Engravings, 6s. 6d. (1873) DIAGRAMS OF THE NERVES OF THE HUMAN BODY, Exhibiting their Origin, Divisions, and Connexions, with their Distri- bution, by Win~1am Henry Fiower, F.R.S., Conservator of the Museum of the Royal College of Surgeons. Second Edition, roy. 4to, 126, (1872) — en ee —. PUBLISHED BY J. AND A. CHURCHILL ll AN ATLAS OF HUMAN ANATOMY: illustrating most of the ordinary Dissections, and many not usually practised by the Student. To be completed in 12 or 13 Bi-monthly Parts, each containing 4 Coloured Plates, with Explanatory Text. By Rickman J. Gopuez, M.S., F.R.CS., Assistant Surgeon to University College Hospital, and Senior Demonstrator of Anatomy in University College. Imp. 4to, 7s. 6d. each Part. (1877) THE ANATOMIST’S VADE-MECUM : a System of Human Anatomy by Erasmus Wixson, F.R.C.S., F.R.S. Ninth Edition, by G. Bucuanan, M.A., M.D., Professor of Clinical Surgery in the University of Glasgow, and Henry E. Cuark, F.F.P.S., Lecturer on Anatomy at the Glasgow Royal Infirmary School of Medicine. Crown 8vo, with 371 Engravings, 14s. [1873] PRACTICAL ANATOMY : a Manual of Dissections by CHRISTOPHER HEatTH, F.R.C.S., Surgeon to University College Hospital, and Holme Professor of Surgery in University College. Fourth Edition, crown 8vo, with 16 Coloured Plates and 264 Engravings, 14s. 0877] MEDICAL ANATOMY, by Francis Srsson, M.D., F.R.C.P., F.R.S. Imp. folio, with 21 coloured Plates, cloth, 42s., half-morocco, 50s. [1869] ATLAS OF TOPOGRAPHICAL ANATOMY, after Plane Sections of Frozen Bodies. By WILHELM BRAUNE, Professor of Anatomy in the University of Leipzig. Translated by Epwarp Betuamy, F.R.C.S., Senior Assistant-Surgeon to, and Lecturer on Anatomy, &c., at, Charing Cross Hospital. With 34 Photo- lithographic Plates and 46 Woodcuts. Large Imp. 8vo, 40s. (1877] THE STUDENT'S GUIDE TO THE PRACTICE OF MEDICINE, by Marruew Cuarreris, M.D., Professor of Medicine in Anderson’s College, and Lecturer on Clinical Medicine in the Royal Infirmary, Glasgow. With Engravings on Copper and Wood, feap. 8vo, 6s. 6d, 2877) THE STUDENT'S GUIDE TO MEDICAL DIAGNOSIS, by Samvet Fenwick, M.D., F.R.C.P., Physician to the London Hospital. Fourth Edition, feap. 8vo, with 106 Engravings, 6s. 6d. 876) A MANUAL OF MEDICAL DIAGNOSIS, by A. W. Barctay, M.D., F.R.C.P., Physician to, and Lecturer on Medicine at, St. George’s Hospital. Third Edition, feap 8vo, 10s. 6d. a] THE ANATOMICAL REMEMBRANCER; oa or, Complete Pocket Anatomist. Eighth Edition, 32mo, 3s. 6d. [876] HOOPER’S PHYSICIAN’S VADE-MECUM ; or, Manual of the Principles and Practice of Physic, Ninth Edition by W. A. Guy, M.B., F.RS., and Joun Hartey, M.D., F.R.C.P. Feap 8vo, with Engravings, 12s. 6d. (1874) 12 CATALOGUE OF RECENT WORKS THE MEDICAL REMEMBRANCER; or, Book of Emergencies. By E. SHaw, M.R.C.S. Fifth Edition by JONATHAN Hurcutnson, F.R.C.S., Senior Surgeon to the i Hospital. 32mo, 2s. 6d. MATERIA MEDICA AND THERAPEUTICS: (Vegetable Kingdom), by Cuartes D. F, Puriurps, M.D., F.R.C.8.E. 8vo, lds. (1874) CLINICAL MEDICINE: ' Lectures and Essays by BALTHAzAr Foster, M.D., F.R.C.P. Lond., Professor of Medicine in Queen’s College, Birmingham. 8vo, “n = CLINICAL STUDIES: Illustrated by Cases observed in Hospital and Private Practice, by Sir J. Rosz Cormack, M.D., F.R.S.E., Physician to the Hertford British Hospital of Paris. 2 vols., post 8vo, 20s. [1876] ROYLE’S MANUAL OF MATERIA MEDICA AND THERAPEUTIOS. ~ Sixth Edition by Jonn Harury, M.D., Assistant Physician to, and Joint Lecturer on Physiology at, St. Thomas’s Hospital. Crown 8vo, with 139 Engravings, 15s. [1876] PRACTICAL THERAPEUTICS : A Manual by E. J. Warine, M.D., F.R.C.P. Lond. Third Edition, feap 8vo, 12s. 6d. (1871) THE STUDENT'S GUIDE TO MATERIA MEDICA, by Joun C. THorowcoop, M.D. Lond., Physician to the City of London Hospital for Diseases of the Chest. Feap 8vo, with Engray- ings, 6s. 6d. [1874] THE DISEASES OF CHILDREN : A Practical Manual, with a Formulary, by Epwarp Exuis, M.D., — Physician to the Victoria Hospital for Children. Third Edition, crown 8vo. {In the Press] THE WASTING DISEASES OF CHILDREN, by Eustace Sm1ru, M.D. Lond., Physician to the King of the Belgians, Physician to the East London Hospital for Children. Second Edition, post 8vo, 7s. 6d. (1870) BY THE SAME AUTHOR, CLINICAL STUDIES OF DISEASE IN CHILDREN. : Post 8vo, 7s. 6d. Ske INFANT FEEDING AND ITS INFLUENCE ON LIFE; or, the Causes and Prevention of Infant Mortality, by CHar es H. F. Rovutu, M.D., Senior Physician to the Samaritan Hospital for Women and Children. Third Edition, fcap 8vo, 7s. 6d. (1876) COMPENDIUM OF CHILDREN’S DISEASES: | A Handbook for Practitioners and Students, by Jonann STEINER, M.D., Professor in the University of Prague. Translated from the Second German Edition by Lawson Tarr, F.R.C.8., Surgeon to the Birmingham Hospital for Women. 8vo, 12s. 6d. (1874) CC — me, PUBLISHED BY J. AND A. CHURCHILL 13 , THE DISEASES OF CHILDREN: Essays by Wiz1t1am Henry Day, M.D., Physician to the Samaritan Hospital for Diseases of Women and Children. Feap 8vo, 5s. _ 873] PUERPERAL DISEASES: Clinical Lectures by Forpycr Barker, M.D., Obstetric Physician to Bellevue Hospital, New York. 8vo, 15s. [1874] THE STUDENT'S GUIDE TO THE PRACTICE OF MIDWIFERY, by D. Lioyp Roserts, M.D., Physician to St. Mary’s Hospital, Man- chester. Feap. 8vo, with 95 Engravings, 6s. 6d. [1875] OBSTETRIC MEDICINE AND SURGERY, Their Principles and Practice, by F. H. Ramssoruam, M.D., F.R.C.P. Fifth Edition, 8vo, with 120 Plates, 22s. [1867] OBSTETRIC APHORISMS: for the Use of Students commencing Midwifery Practice by J. G. Swayne, M.D., Consulting Physician-Accoucheur to the Bristol General Hospital, and Lecturer on Obstetric Medicine at the Bristol Medical School. Sixth Edition, feap 8vo, with Engravings, 3s. 6d. 1876} OBSTETRIC SURGERY: A Complete Handbook, giving Short Rules of Practice in every Emer- gency, from the Simplest to the most Formidable Operations connected with the Science of Obstetricy, by CHarLEs Cay, Ext.L.R.C.P. Lond., — L.R.C.S.E., late Senior Surgeon and Lecturer on Midwifery, St. Mary’s Hospital, Manchester. Fcap 8vo, with 91 Engravings, 6s. 6d. (1874) SCHROEDER’S MANUAL OF MIDWIFERY, including the Pathology of Pregnancy and the Puerperal State. Translated by CHARLES H. Carter, B.A., M.D. 8vo, with Engrav- ings, 12s. 6d. (1873) A HANDBOOK OF UTERINE THERAPEUTICS, and of Diseases of Women, by E. J. Tritt, M.D., M.R.C.P. Third Edition, post 8vo, 10s. (1868) BY THE SAME AUTHOR, THE CHANGE OF LIFE in Health and Disease: a Practical Treatise on the Nervous and other Affections incidental to Women at the Decline of Life. Third Edition, 8vo, 10s. 6d. 11870 DISEASES OF THE OVARIES: their Diagnosis and Treatment, by T. SPENcER Wetts, F.R.CS., Surgeon to the Queen’s Household and to the Samaritan Hospital. Svo, with about 150 Engravings, 21s. [1872] PRACTICAL GYNACOLOGY : A Handbook of the Diseases of Women, by Heywoop Smita, M.D. Oxon., Physician to the Hospital for Women and to the British Lying- in Hospital. With Engravings, crown 8vo, 5s. 6d. (1877) 14 CATALOGUE OF RECENT WORKS OBSTETRIC OPERATIONS, ¥ including the Treatment of Hemorrhage, and forming a Guide to the Management of Difficult Labour; Lectures by RoBpERT Barngzs, M.D., F.R.C.P., Obstetric Physician and Lecturer on Obstetrics and the Dis- eases of Women and Children at St. George’s Hospital. Third Edition, 8vo, with 124 Engravings, 18s. (1875) BY THE SAME AUTHOR, ; MEDICAL AND SURGICAL DISEASES OF WOMEN: a Clinical History. Second Edition, 8vo, with many Engravings. — (In the Press} HANDBOOK FOR NURSES FOR THE SICK, by ZEPHERINA P. VerrcH. Second Edition, crown 8vo, 3s, 6d. 876) A MANUAL FOR HOSPITAL NURSES ' and others engaged in Attending on the Sick by Epwarp J. Dom- VILLE, L.R.C.P., M.R.O.8. Second Edition, crown 8vo, 2s, 6d. 1875) _~ THE NURSE’S COMPANION: A Manual of General and Monthly Nursing, by CoartEs J. CULLING- wortH, Surgeon to St. Mary’s Hospital, Manchester. Feap. 8vo, 2s. 6d. [1876] LECTURES ON NURSING, by Wixtt1am Rosert Smiru, M.B., late Resident Surgeon, Royal Hants County Hospital, Winchester. Second Edition, with Engray- ings. Post 8vo. (in the Press} THE COTTAGE HOSPITAL: Its Origin, Progress, Management, and Work, hy Henry C. Burpert, the Seaman’s Hospital, Greenwich. With Engravings, crown 8vo, 7s. 6d. (1877J HOSPITAL MORTALITY : being a Statistical Investigation of the Returns of the Hospitals of Great Britain and Ireland for fifteen years, by Lawson Tart, F.R.O.S., F.S.8. 8vo, 6s. [1877] ENGLISH MIDWIVES: their History and Prospects, by J. H. Avetine, M.D., Physician to the Chelsea Hospital for Women, Examiner of Midwives for the Obstetrical Society of London. Crown 8vo, 5s. (1872) A COMPENDIUM OF DOMESTIC MEDICINE and Companion to the Medicine Chest; intended as a Source of Hasy Reference for Clergymen, and for Families residing at a Distance from Professional Assistance, by Joun Savory, M.S.A. Highth Bdition, 12mo, 5s. (1871) THE WIFE’S DOMAIN: The Young Couple—The Mother—The Nurse—The Nursling, by Put- LOTHALOS. Second Edition, post 8vo, 3s. 6d. (1874) PUBLISHED BY J. AND A. CHURCHILL 15. WINTER COUGH: (Catarrh, Bronchitis, Emphysema, Asthma), Lectures by Horace Doset1,M.D., Consulting Physician to the Royal Hospital for Diseases. of the Chest. Third Edition, with Coloured Plates, 8vo, 1s. 6d. 875}, BY THE SAME AUTHOR, THE TRUE FIRST STAGE OF CONSUMPTION. (Lectures.) Crown 8vo, 3s. 6d. (1867). DISEASES OF THE CHEST: Contributions to their Clinical History, Pathology, and Treatment, by A. T. H. Waters, M.D., F.R.C.P., Physician to the Liverpool Royal Infirmary. Second Edition, 8vo, with Plates, 15s. [1873] NOTES ON ASTHMA; its Forms and Treatment, by Joun C. THorowcoop, M.D. Lond., F.R.C.P., Physician to the Hospital for Diseases of the Chest, Victoria Park. Second Edition, crown 8vo, 4s. 6d. [1873]. PROGNOSIS IN CASES OF VALVULAR DISEASE OF THE. Heart, by Toomas B. Peacock, M.D., F.R.C.P., Honorary Consult- ing Physician to St. Thomas’s Hospital. 8vo, 3s. 6d. (1877} DISEASES OF THE HEART: Their Pathology, Diagnosis, Prognosis, and Treatment (a Manual), by Rosert H. Szemp ez, M.D., F.R.C.P., Physician to the Hospital for Diseases of the Throat. 8vo, 8s. 6d. (1875) DISEASES OF THE HEART AND AORTA, By THomas Haypen, F.K.Q.C.P. Irel., Physician to the Mater Misericordiw# Hospital, Dublin. With80Engravings. 8vo, 25s. [875] PHTHISIS : In a series of Clinical Studies, by Austin Fuint, M.D., Professor of the Principles and Practice of Medicine and of Clinical Medicine in the Bellevue Hospital Medical College. 8vo, 16s. 1875} BY THE SAME AUTHOR, A MANUAL OF PERCUSSION AND AUSCULTATION, of the Physical Diagnosis of Diseases of the Lungs and Heart, and of Thoracic Aneurism. Post 8vo, 6s. 6d. (1876} GROWTHS IN THE LARYNX, with Reports and an Analysis of 100 consecutive Cases treated since the Invention of the Laryngoscope by Moretti Mackenzie, M.D. Lond., M.R.C.P., Physician to the Hospital for Diseases of the Throat. 8vo, with Coloured Plates, 12s. 6d. 1871) 16 CATALOGUE OF RECENT WORKS DISEASES OF THE HEART and of the Lungs in Connexion therewith—Notes and Observations by THomas Suapter, M.D., F.R.C.P. Lond., Senior Physician to the Devon and Exeter Hospital. 8vo, 7s. 6d. _ (1874) DISEASES OF THE HEART AND AORTA: Clinical Lectures by Gzorer W. Batrour, M.D., F.R.C.P., Physician to, and Lecturer on Clinical Medicine in, the Royal Infirmary, Edin- burgh. 8vo, with Engravings, 12s. 6d. (1876) PHYSICAL DIAGNOSIS OF DISEASES OF THE HEART. Lectures by ArTHUR E. Sansom, M.D., Assistant Physician to the London Hospital. Second eee with Engravings, feap. 8vo, nye a TRACHEOTOMY, especially in Relation to Diseases of the Larynx and "Tash, % P Pucin THornton, M.R.C.S., late Surgeon to the Hospital for Diseases of the Throat. With Photographic Plates and Woodcuts, 8vo, a SKETCH OF CANNES AND ITS CLIMATE, by Tu. Dz Vatcourr, M.D. Paris, Physician at Cannes. Second Edition, with Photographic View and 6 Meteorological Charts. Crown 8vo, 2s. 6d. : (1873) WINTER AND SPRING on the Shores of the Mediterranean ; or, the Genoese Rivieras, Italy, Spain, Greece, the Archipelago, Constantinople, Corsica, Sardinia, Sicily, Corfu, Malta, Tunis, Algeria, Smyrna, Asia Minor, with Biarritz and Arcachon, as Winter Climates. By Henry BENNET, M.D. Fifth Edition, post 8vo, with numerous Plates, Maps, and Engravings, 12s. 6d. (1874) BY THE SAME AUTHOR, TREATMENT OF PULMONARY CONSUMPTION by Hygiene, Climate, and Medicine. Second Edition, 8vo, 5s. (1871) PRINCIPAL HEALTH RESORTS of Europe and Africa, and their Use in the Treatment of Chronic Diseases. A Handbook by THomas More Mappen, M.D., M.R.LA., Vice-President of the Dublin Obstetrical Society. 8vo, 10s. 1876) MINERAL SPRINGS OF HARROGATE, By Dr. Kennion. Revised and enlarged by ADAM BEALEY, M.A, M.D. Cantab., F.R.C.P. Lond. Seventh Thousand. Crown 8vo, a A THE BATH THERMAL WATERS: Historical, Social, and Medical, by Jonn Kent SpenpeErR, M.D., Surgeon to the Mineral Water Hospital, Bath. With an Appendix on the Climate of Bath by the Rev. L. Buomerrexp, M.A., F.LS., F.G.8. 8vo, 7s. 6d. [1877] PUBLISHED BY J. AND A. CHURCHILL 17 PAMILY MEDICINE FOR INDIA: . ' A Manual, by Win11am J. Moorg, M.D., Surgeon-Major H.M. Indian Medical Service. Published under the Authority of the Government of India. Third Edition, post 8vo, with 60 Engravings. (In the press} DISEASES OF TROPICAL CLIMATES and their Treatment: with Hints for the Preservation of Health in the Tropics, by James A. Horton, M.D., Surgeon-Major, Army Medical Department. Post 8vo, 12s. 6d. (1874) _ ENDEMIC DISEASES OF TROPICAL CLIMATES, with their Treatment, by Jonn Sunirvan, M.D., M.R.C.P. Post 8vo, 6s. [1877] HEALTH IN INDIA FOR BRITISH WOMEN and on the Prevention of Disease in Tropical Climates by Epwarp J. Tiut, M.D., Consulting Physician-Accoucheur to the Farringdon General Dispensary. Fourth Edition, crown 8vo, 5s. [1875] BURDWAN FEVER, or the Epidemic Fever of Lower Bengal (Causes, Symptoms, and Treatment), by Gorpaut CHuNDER Roy, M.D., Surgeon Bengal Establishment. New Edition, 8vo, 5s. [1876] BAZAAR MEDICINES OF INDIA and Common Medical Plants: Remarks on their Uses, with Full Index of Diseases, indicating their Treatment by these and other Agents pro- eurable throughout India, &c., by Epwarp J. Warine, M.D., F.R.C.P. Lond., Retired Surgeon H.M. Indian Army. Third Edition. Fcap 8vo, 5s. (1875) SOME AFFECTIONS OF THE LIVER and Intestinal Canal; with Remarks on Ague and its Sequele, Scurvy, Purpura, &c., by SrepHen H. Warp, M.D. Lond., F.R.C.P., Physician to the Seamen’s Hospital, Greenwich. 8vo, 7s. (1872) DISEASES OF THE LIVER: Lettsomian Lectures for 1872 by 8. O. iseamnon M.D., F.R.C.P., Senior Physician to Guy’s Hospital. Post 8vo, 3s. 6d. [1872] BY THE SAME AUTHOR, DISEASES OF THE STOMACH: DYSPEPSIA. Second Edition, crown 8vo, 5s. - BY THE SAME AUTHOR, PATHOLOGY OF THE PNEUMOGASTRIC NERVE, being the Lumleian Lectures for 1876. Post 8vo, 3s. 6d. 1877) FUNCTIONAL NERVOUS DISORDERS : Studies by C. Hanprreip Jones, M.B., F.R.C.P., F.R.S., Physician to St. Mary’s Hospital. Second Edition, 8vo, 18s. (1870) 18 CATALOGUE OF RECENT WORKS NUTRITION IN HEALTH AND DISEASE: A Contribution to Hygiene and to Clinical Medicine. By Henry Bennet, M.D. Third Edition. 8vo, 7s. (1877) THE STOMACH AND DUODENUM: Their Morbid States and their Relations to the Diseases of other Organs, by SamureL Fenwick, M.D., F.R.C.P., Physician to the London Hospital. S8vo, with 10 Plates, 12s. (1868), FOOD AND DIETETICS, Physiologically and Therapeutically Considered. By FrepERIcK W, ~ Pavy, M.D., F.R.S., Physician to Guy’s Hospital. Second Edition, 8vo, lds. (1875} HEADACHES: their Causes, Nature, and Treatment. By Wiii1am H. Day, M.D., Physician to the Samaritan Free Hospital for Women and Children, Crown 8vo, with Engravings. 6s. 6d. 877) IMPERFECT DIGESTION : its Causes and Treatment by ArTHuR LxearepD, M.D., F.R.C.P., Senior Physician to the Great Northern Hospital. Sixth Edition, feap 8vo, 4s. 6d. 01875} MEGRIM, SICK-HEADACHE, and some Allied Disorders : a Contribution to the Pathology of Nerve- Storms, by Epwarp Liverne, M.D. Cantab., Hon. Fellow of King’s College, London, 8vo, with Coloured Plate, lds. [1878] NEURALGIA AND KINDRED DISEASES of the Nervous System: their Nature, Causes, and Treatment, with a series of Cases, by Joun CHAPMAN, M.D., M.R.C.P. 8vo, 14s, 878) THE SYMPATHETIC SYSTEM OF NERVES, and their Functions as a Physiological Basis for a Rational System of Therapeutics by Epwarp Meryon, M_D., F.R.C.P., Physician to the Hospital for Diseases of the Nervous System, 8vo, 3s, 6d. (18723 RHEUMATIC GOUT, or Chronic Rheumatic Arthritis of all the Joints; a Treatise by Rosert Apams, M.D., M.R.1.A., late Surgeon to H.M. the Queen in Ireland, and Regius Professor of Surgery in the University of Dublin. Second Edition, 8vo, with Atlas of Plates, 21s. 878] SCIATICA, LUMBAGO, AND BRACHIALGIA : Their Nature and Treatment, and their Immediate Relief and Rapid Cure by Hypodermic Injection of Morphia. By Henry Lawson, M.D., Assistant-Physician to St. Mary’s Hospital, and Lecturer on Physiology in its School. Second edition, crown 8vo, 5s. _ (1877) lit PUBLISHED BY J. AND A. CHURCHILL 1> GOUT, RHEUMATISM, and the Allied Affections; a Treatise by Perer Hoop, M.D. Crown 8vo, 10s. 6d. (1871), CANCER : its varieties, their Histology and Diagnosis, by Henry ARnorrt, F.R.C.S., late Assistant-Surgeon to, and Lecturer on Morbid Anatomy at, St. Thomas’s Hospital. 8vo, with 5 Plates and 22 Engravings, 5s. 6d. (1872), CANCEROUS AND OTHER INTRA-THORAOIC GROWTHS: their Natural History and Diagnosis, by J. Rispon Bennett, M.D.,. F.R.C.P., Member of the General Medical Council. Post 8vo, with Plates, 8s. . (872), CERTAIN FORMS OF CANCER, with a New and successful Mode of Treating it, to which is prefixed a. Practical and Systematic Description of all the varieties of this Disease, by Atex. Marspen, M.D., F.R.C.S.E., Consulting Surgeon to the- Royal Free Hospital, and Senior Surgeon to the Cancer Hospital. Second Edition, with Coloured Plates, 8vo, 8s. 6d. (1873) ATLAS OF SKIN DISEASES: a series of Illustrations, with Descriptive Text and Notes upon Treat« ment. By Trupury Fox, M.D., F.R.C.P., Physician to the Department for Skin Diseases in University College Hospital. With 72 Coloured Plates, royal 4to, half morocco, £6 6s. 1877}, DISEASES OF THE SKIN: a System of Cutaneous Medicine by Erasmus Writson, F.R.C5.,. F.R.S. Sixth Edition, 8vo, 18s., with Coloured Plates, 36s. (ser), BY THE SAME AUTHOR, LECTURES ON EKZEMA and Ekzematous Affections: with an Introduction on the General Pathology of the Skin, and an Appendix of Essays and Cases. 8vo, 10s. 6d. (1870} ALSO, LECTURES ON DERMATOLOGY : delivered at the Royal College of Surgeons, 1870, 6s. ; 1871-3, 10s. 6d., 1874-5, 10s. 6d. ECZEMA : by McCatt ANDERSON, M.D., Professor of Clinical Medicine in the University of Glasgow. Third Edition, 8vo, with Engravings, 7s. 6d. (1874}, BY THE SAME AUTHOR, PARASITIC AFFECTIONS OF THE SKIN Second Edition, 8vo, with Engravings, 7s. 6d. (1868), 20 CATALOGUE OF RECENT WORKS PSORIASIS OR LEPRA, by Grorce Gasxorn, M.R.OC.8., Surgeon to the British Hospital for Diseases of the Skin. 8vo, 5s. (1875) MYCETOMA ; or, the Fungus Disease of India, by H. VanpyKke Carrer, M.D., Sur- geon-Major H.M. Indian Army. 4to, with 11 Coloured Plates, er 3 CERTAIN ENDEMIC SKIN AND OTHER DISEASES of India and Hot Climates generally, by Trnpury Fox, M.D., and T. FarquHar, M.D. (Published under the sanction of the Secretary of State for India in Council). 8vo, 10s. 6d. 1876) © DISEASES OF THE SKIN, in Twenty-four Letters on the Peseta and Practice of Cutaneous Medicine, by Henry Evans Caurty, Surgeon to the Liverpool Dis- pensary for Diseases of the Skin, 8vo, 12s. 6d. 0874] ‘THE HAIR IN HEALTH AND DISEASE, by E. Wynpuam Corrie, F.R.C.S., Senior Assistant Surgeon to the Hospital for Diseases of the Skin, Blackfriars. Feap. 8vo, 2s.6d. [877] WORMS: a Series of Lectures delivered at the Middlesex Hospital on Practical Helminthology by T. Spencer Copsoup, M.D., F.R.S. Post 8vo, 5s. 1872] THE LAWS AFFECTING MEDICAL MEN: , a Manual by Rosert G. Gurenn, LL.B., Barrister-at-Law; with a Chapter on Medical Etiquette by Dr. A. CARPENTER. 8vo, 14s. 0871) MEDICAL JURISPRUDENCE, : Its Principles and Practice, by AtrrED §. Taytor, M.D., F.R.C.P., F.R.8. Second Edition, 2 vols., 8vo, with 189 Engravings, £1 11s. 6d. © [1873] BY THE SAME AUTHOR, A MANUAL OF MEDICAL JURISPRUDENCE. Ninth Edition. Crown 8vo, with Engravings, 14s. (1874) ALSO, POISONS, in Relation to Medical Jurisprudence and Medicine. Third Edition, crown 8vo, with 104 Engravings, 16s. [1875] A TOXICOLOGICAL CHART, exhibiting at one View the Symptoms, Treatment, and mode of Detecting the various Poisons—Mineral, Vegetable, and Animal: with Concise Directions for the Treatment of Suspended Animation, by Witt1am Stowe, M.R.C.S.E. Thirteenth Edition, 2s.; on roller, 5s. [1872] PUBLISHED BY J. AND A. CHURCHILL 21 A HANDY-BOOK OF FORENSIC MEDICINE AND TOXICOLOGY, by W. Baruurst Woopmay, M.D., F.R.C.P., Assistant Physician and Co-Lecturer on Physiology and Histology at the London Hospital ; and ©. Meymorr Trpy, M.D., F.C.S., Professor of Chemistry and of Medical Jurisprudence and Public Health at the London Hospital. With 8 Lithographic Plates and 116 Engravings, 8vo, 31s.6d. 0877) THE MEDICAL ADVISER IN LIFE ASSURANCE, by Epwarp Henry Srevexine, M.D., F.R.C.P., Physician to St. Mary’s and the Lock Hospitals; Physician-Extraordinary to the Queen; Physician-in-Ordinary to the Prince of Wales, &. Crow 8vo, 6s. [1874] IDIOCY AND IMBECILITY, by Writ1am W. Iretanp, M.D., Medical Superintendent of the Scottish National Institution for the Education of Imbecile Children at Larbert, Stirlingshire. With Engravings, 8vo, 14s. (1877} PSYCHOLOGICAL MEDICINE : a Manual, containing the Lunacy Laws, the Nosology, Aitiology, Statistics, Description, Diagnosis, Pathology (including Morbid His- tology), and Treatment of Insanity, by J. C. Bucxniiy, M.D., F.B.S., and D. H. Tuxe, M.D., F.R.C.P. Third Edition, 8vo, with 10 Plates and 34 Engravings, 25s. (18732 MADNESS : in its Medical, Legal, and Social Aspects, Lectures by EpGar SHEPPARD, M.D., M.R.C.P., Professor of Psychological Medicine in King’s College; one of the Medical Superintendents of the Colney Hatch Lunatic Asylum. 8vo, 6s. 6d. 11873} HANDBOOK OF LAW AND LUNACY; or, the Medical Practitioner’s Complete Guide in all Matters relating to Lunacy Practice, by J. T. Sassen, M.D., and J. H. Batrour Browne, Barrister-at-Law. 8vo, 5s. (1872), INFLUENCE OF THE MIND UPON THE BODY in Health and Disease, Illustrations designed to elucidate the Action of the Imagination, by Danret Hack Tuxz, M.D., F.R.C.P. 8vo, 14s. ~ (1872) A MANUAL OF PRACTICAL HYGIENE, by E. A. Parkes, M.D., F.R.O.P., F.R.S. Fifth Edition. Edited by F. De Cxaumont, M.D., Professor of Military Hygiene in the Army Medical Service. 8vo, with Plates and Engravings. (In the press.) A HANDBOOK OF HYGIENE AND SANITARY SCIENCE, by Groner Witson, M.A., M.D., Medical Officer of Health for Mid- Warwickshire. Third Edition, post 8vo, with Engravings, 10s. ay Pe 22 CATALOGUE OF RECENT WORKS MICROSCOPIOAL EXAMINATION OF DRINKING WATER: A Guide, by Joun D. Macponanp, M.D., F.R.S., Assistant Pro- fessor of Naval Hygiene, Army Medical School. 8vo, with 24 Plates, 7s. 6d. 1875} HANDBOOK OF MEDICAL AND SURGICAL ELECTRICITY, by Hersert Trssits, M.D., F.R.C.P.E., Medical Superintendent of the National Hospital for the Paralysed and Epileptic. 8vo, with 95 Engravings, 9s. 01877] BY THE SAME AUTHOR. -A MAP OF ZIEMSSEN’S MOTOR POINTS OF THE HUMAN BODY: a Guide to Localised Electrisation. Mounted on Rollers, 35 x 21. With 20 Illustrations, 5s. (1877} CLINICAL USES OF ELECTRICITY ; Lectures delivered at University College Hospital by J. Russmnnm Reynoups, M.D. Lond., F.R.C.P., F.R.S., Professor of Medicine in University College. Second Edition, post 8vo, 3s. 6d. 11878] MEDICO-ELECTRIC APPARATUS: | A Practical Description of every Form in Modern Use, with Plain | Directions for Mounting, Charging, and Working, by Satt & Son, Birmingham. Second Edition, revised and enlarged, with 33 Engray- | ings, 8vo, 2s. 6d. (18771 | A DICTIONARY OF MEDICAL SCIENCE; containing a concise explanation of the various subjects and terms of Medicine, &c.; Notices of Climate and Mineral Waters; Formule for Officinal, Empirical, and Dietetic Preparations ; with the Accentuation and Etymology of the terms and the French and other Synonyms, by Rosier Dunewison, M.D., LL.D. New Edition, royal 8vo, 28s. [874] A MEDICAL VOCABULARY ; : being an Explanation of all Terms and Phrases used in the various Departments of Medical Science and Practice, giving their derivation, meaning, application, and pronunciation, by Ropert G. Maynz, M.D., LL.D. Fourth Edition, feap 8vo, 10s. [1875] ATLAS OF OPHTHALMOSOOPY, by R. Lizsreicu, Ophthalmic Surgeon to St. Thomas’s Hospital. Translated into English by H. Rosnoroven Swanzy, M.B. Dub. Second Edition, containing 59 Figures, 4to, £1 10s. (1870} DISEASES OF THE EYE: a Manual by C. Macnamara, Surgeon to Westminster Hospital. Third Edition, feap, 8vo, with Coloured Plates and Engravings, 12s. 6d. (1876) DISEASES OF THE EYE: A Practical Treatise by Haynes Waurton, F.R.C.S., Surgeon to St. Mary’s Hospital and in charge of its Ophthalmological Department. Third Edition, 8vo, with 3 Plates and nearly 300 Engravings, 25s. [1875] . PUBLISHED BY J. AND A. CHURCHILL 23 HINTS ON OPHTHALMIC OUT-PATIENT PRACTICE, by Cuar.es Hieeens, F.R.C.S., Ophthalmic Assistant Surgeon to, and Lecturer on Ophthalmology at, Guy’s Hospital. 87 pp., feap. 8vo, Qs. 6d. 01877) OPHTHALMIC MEDICINE AND SURGERY: a Manual by T. Wuarron Jonzs, F.R.S., Professor of Ophthalmic Medicine and Surgery in University College. Third Edition, feap 8vo, with 9 Coloured Plates and 173 Engravings, 12s. 6d. (1865) DISEASES OF THE EYE: A Treatise by J. SontperG WELLS, F.R.C.S., Ophthalmic Surgeon to King’s College Hospital and Surgeon to the Royal London Ophthalmic Hospital. Third Edition, 8vo, with Coloured Plates and Engravings, 25s. 0873) BY THE SAME AUTHOR, LONG, SHORT, AND WEAK SIGHT, and their Treatment by the Scientific use of Spectacles. Fourth Edition, 8vo, 6s. [1873] A SYSTEM OF DENTAL SURGERY, by Joun Tomes, F.R.S., and Cuaries 8. Tomes, M.A., Lecturer on Dental Anatomy and Physiology at the Dental Hospital of London. Second Edition, feap 8vo, with 268 Engravings, 14s. [1873] DENTAL ANATOMY, HUMAN AND COMPARATIVE: A Manual, by Cuarues S. Tomes, M.A., M.R.C.S., Lecturer on Anatomy and Physiology at the Dental Hospital of London. With 179 Engravings, crown 8vo, 10s. 6d. [1876] A MANUAL OF DENTAL MECHANICS, with an Account of the Materials and Appliances used in Mechanical Dentistry, by Oaxiey Coes, L.D.S., R.C.S., Surgeon-Dentist to the Hospital for Diseases of the Throat. Second Edition, crown 8vo, with 140 Engravings, 7s. 6d. [1876] HANDBOOK OF DENTAL ANATOMY and Surgery for the use of Students and Practitioners by Jonn Smrru, M.D., F.R.S. Edin., Surgeon-Dentist to the Queen in Scotland. Second Edition, fcap 8vo, 4s. 6d. (1871) STUDENT'S GUIDE TO DENTAL ANATOMY AND SURGERY, by Henry Srewitt, M.R.C.S., L.D.S., Dentist to the West London Hospital. With 77 Engravings, feap. 8vo, 5s. 6d. (1876) OPERATIVE DENTISTRY: A Practical Treatise, by JonatHan Tart, D.D.S., Professor of Opera- tive Dentistry in the Ohio College of Dental Surgery. Third Edition, thoroughly revised, with many additions, and 134 Engravings, 8vo, 18s. [1877] EPIDEMIOLOGY ; or, the Remote Cause of Epidemic Diseases in the Animal and in the Vegetable Creation, by JoHN Parkin, M.D., F.R.O.S. Part I, Contagion—Modern Theories—Cholevra—Epizootics. 8vo, 5s. 1878) (\ The following CaraLoauns issued by Messrs CuurcHiLh — will be forwarded post free on application : 1. Messrs Churchill’s General List of nearly 600 ween Medicine, Surgery, Midwifery, Materia Medica, Hygi Anatomy, Physiology, Chemistry, §c., §¢., with a complet Index to their Titles, for easy reference. N.B.—This List includes Nos. 2 and 3. 2. Selection from Messrs Churchill’s General List, com- | \ prising all recent Works published by them on the Am and — Science of Medicine. 3. A descriptive Iist of Messrs Churchill's Works om Chemistry, Pharmacy, Botany, Photography, Zoology, and other branches of Science. aa 4. Messrs Churchill’s Red-Letter List, giving the Titles | of forthcoming New Works and New Editions. [Published every October.} i 4 i 5. The Medical Intelligencer, an Annual List of New Works and New Editions published by Messrs J. & A. Ohurchill, together with Particulars of the Periodicals issued from their House. [Sent in January of each year to every Medical Practitioner in | . the United Kingdom whose name and address can be ascertained. A large number are also sent to the United States of America, 4 Continental Europe, India, and the Colonies. } Messrs CHURCHILL have a special arrangement with Mxssrs LINDSAY & BLAKISTON, or Purmaperruta, in accordance with which that Firm act as their Agents for the United States of America, either keeping in Stock most of Messrs Cuvrcu111’s Books, or reprint- ing them on Terms advantageous to Authors. Many of the Works in this Catalogue may therefore be easily obtained in America. PRINTED BY J. E. ADLARD, BARTHOLOMEW CLOSE. te : REMOVE |. THE CARD FROM THIS POCKET Year ae Se ‘Acme ibrary Card Pock aoe RTIN co. imn eae 128 b hal Lh a tee CEN LY MA rrr " E os jerd ze a Eee