THE COMPARATIVE ANATOMY OP THE DOMESTICATED ANIMALS. THE COMPARATIVE ANATOMY DOMESTICATED ANIMALS. By a. CHAUVEAU, PROFESSOR AT THE LYONS VETERINARY SCHOOL. ^ttmH €bitiort, '^tinBtii nxitu §nhtQzh, foit^ t^e €o'0^txnixon of S. ARLOING, LATE PKINCIPAL OF ANATOMY AT THE LYONS VETERINARY SCHOOL; PROFESSOR AT THE T0IJL0F8E VETERINARY SCHOOL. TRANSLATED AND EDITED BY GEORGE FLEMING, F. R. G. S., M A. I., VETERINARY SURGEON, ROYAL ENGINEERS, ATTTHOR OP "TRAVELS ON HORSEBACK IN MANTCHF TARTARY,'*' " HORSE-SHOES AND HORSE-SHOEING,'' "ANIMAL PLAGUES,'' "PRACTICAL HORSE-SHOEING," "RABIES AND HYDROPHOBIA," ETC. WITH 450 ILLUSTRATIONS. NEW YORK: D. APPLETOK AKD COMPAlSrY, 549 & 551 BROADWAY. 1873. TO THE MEMORY OF JOHN LAW SON, M. E.C.V.S., OF MANCHESTEE, WHO FIRST URGED THE DESIRABILITY OF UNDERTAKING THIS TASK, AND WHOSE SINCERE AND INESTIMABLE FRIENDSHIP AND ENCOURAGEMENT FOR MANY YEARS THE EDITOR AND TRANSLATOR HEREBY ACKNOWLEDGES WITH SORROWFUL AFFECTION AND GRATITUDE. PEEFACE BY THE TEANSLATOR AND EDITOR. In undertaking the arduous task of translating and editing the ' Traite d* Anatomie Comparee des Animaux 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 mau, 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 experieuce 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 FBEFACB 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 llian a century, the French veterinary schools have been celebrated for the careful and thorough manner in which anatomy has been taught by most ef&cient 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 1 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 bemg 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 PBEFACE 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 Eabbit; 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, 1 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. GEOEGE FLEMING. Beompton Barracks, Chatham. February, 1873. 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 elementary treatise. Ko 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 PBEFACE TO THE FJEST 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 ^vas 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 Geoffrey Saint-Hilaire ; tvvo 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 PBEFACE TO THE FIEST EDITION, xiii brouglit witbin those laws of uniformity whicli sliine 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 Geoffrey 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 elevated 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 PBEFACB TO THE FIBST 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 have 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. Eodet 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. Chauveau. Lyons, September 30, 1854. PREFACE TO THE SECOND EDITION. CiECUMSTANCES 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, March mh, 1872, TABLE OP CONTENTS. Translator and Editor's Preface Preface to the First Edition . Preface to the Second Edition Table of Contents Table of Illustrations PAGE vii xi XV xvii xxxvi GENERAL CONSIDEKATIONS. Definition and Division of Anatomy ...... Enumeration and Classification of the Domesticated Animals . General Idea of the Organisation of Animals, and the order followed in studying their apparatus ......... BOOK I. LOCOMOTORY APPARATUS. First Section. — The Bones ..... Chapter I. — The Bones in General .... Article i. — The Skeleton ..... Article ii. — General Principles applicable to the Study of all the Bones Name, Situation, Direction, and Configuration of the Bones Internal Conformat'oa of the Bones. Structure of the Bones Development of the Bones .... Chapter II. — The Bones of Mammalia in Particular Article i. — Vertebral Column .... Characters Common to all tlie Vertebrae Characters Proper to the Veittbrse in each region 1. Cervical Vertebrae . . . - . 2. Dorsal Vertebrse ..... 3. Lumbar Vertebrae ..... 4. Sacrum ...... 5. Coccygeal Vertebrae ..... Of the Spine in General .... Differential Characters in the Vertebral Column of other than Animals ...... Comparison of the Vertebral Column of Man with that of Animals Article ii. — Tne Head ..... The Bones of the Cranium ..... 1. Occipital . . .... 2. Parietal ....... 3. Frontal . ^ . . . . 2 . 6 6 . 7 les 10 10 13 16 18 18 19 . 21 21 , 24 25 26 27 28 Solipec I 29 32 33 . 33 33 » 35 36 xviii TABLE OF CONTENTS. PAGE 4. Eth-inoid . . v , . . . . 37 39 41 44 44 45 46 47 47 48 48 49 51 51 53 54 55 63 m m 66 67 70 70 70 71 71 71 71 71 72 72 73 73 75 75 76 77 78 81 82 5. Sphenoid ....... 6. Temporal ...... The Bones of the Face ...... 1. Superior Maxillary or Great Supermaxillary 2. Intermaxilla, Incisive Bone, Small Supermaxilla, or Premaxilla 3. Palate . 4. Pterygoid .... 5. Zygomatic 6. Lachrymal .... 7. Bones proper to the Nose, or Supernasal 8. Turbinated Bones 9. Vomer .... 10. Inferior Maxillary 11. Hyoid . . Of the Head in General . . . . . . Differential Characters in the Head of other than Soliped Animals Comparison of the Head of Man with that of Animals Article in. — The Thorax . . . . . . The Bones of the Thorax in Particular .... 1. Sternum of the Horse . . . 2. Eibs ........ Of the Thorax in General ..... Differential Characters in the Thorax of other than Soliped Animals 1. Sternum ....... 2. Eibs Comparison of the Thorax of Man with that of Animals 1. Sternum . . ... 2. Eibs ....... Article rv. — Anterior Limbs ...... Shoulder ....... Scapula ........ Arm . . . . Humerus ........ Fore-arm ....... 1. Eadius ....... 2. Ulna . Anterior Foot ....... 1. Bones of the Carpus ..... 2. Bones of the Metacarpus ..... 3. Bones of the Digit, or Phalangeal Eegion . Differential Characters in the Anterior Limb of other than Soliped Animals Comparison of the Thoracic Limb of Man with that of the Domesticated Animals Article v. — Posterior Limbs Pelvis .... A. CoxsB B. The Pelvis in General Tliigh .... Femur .... Leg .... 1. Tibia .... 2. Fibula . 3. Patella 91 91 91 95 98 98 100 100 101 102 TABLE OF CONTENTS. six PAGE Posterior Foot ...>.... 102 1. Bones of the Tarsus . . . . . » .102 2. Bones of the Metatarsus . . , . . .105 3. Bones of the Digital Kegion . , . . . , 105 Differential Characters in the Posterior Limb of other than Soliped Animals ........ 105 Comparison of the Abdominal Limb of Man with that of the Domesticated Animals . . . . . . , . 107 Article vi. — The Limbs in General, and their Parallelism . 109 Chapter III. — The Bones in Birds . . . . . .112 Chapter IV. — Theory of the Vertebral Constitution of the Skeleton . 118 Second Section. — The Articulations ...... 121 Chapter I. — The Articulations in General ..... 121 General Characters of Diarthroses . . . . . .123 General Characters of Synarthroses ..... 128 General Characters of Amphiarthroses or Symphyses . . . 129 Chapter II. — The Articulations of Mammalia in Particular . . 129 Article I.; — Articulations of the Spine . . . . .130 Articulations between the Vertebrae, or Intervertebral Articulations . 130 Article ii. — Articulations of the Head ..... 135 1. Atlo-axoid Articulation . . . . . , 135 2. Occipito-atloid Articulation ...... 137 3. Articulations between the Bones of the Head . . . 137 4. Temper o-maxillary Articulation . . . . .138 5. Hyoideal Articulations . . . , . .139 Article III. — Articulations of the Thorax ..... 140 1. Costo- vertebral, or Articulations of the Ribs with the Vertebral Column 140 2. Costo- sternal Articulations . . . . . .141 3. Chondro-costal Articulations, or Articulations between the Ribs . 142 4. Articulations between the Costal Cartilages .... 142 5. Sternal Articulation peculiar to the Ox and Pig . . . 142 6. The Articulations of the Thorax considered in a general manner, with respect to their Movements ..... . 142 Article iv. — Articulations of the Anterior Limbs .... 143 1. Scapulo-humeral Articulation. ..... 143 2. Humero-radial Articulation ..... 144 3. Radio-ulnar Articulation ...... 147 4. Articulations of the Carpus . . . . .148 5. Intermetacarpal Articulations. ..... 152 6. Metacarpo-phalangeal Articulations . . . . 153 7. Articulation of the First Phalanx with the Second, or first Inter- phalangeal Articulation . . . . . .156 8. Articulation of the Second Phalanx with the Third, Second Inter- phalangeal Articulation, or Articulation of the Foot . . 157 Article v. — Articulations of the Posterior Limbs . . . .159 1. Articulations of the Pelvis . . . . .159 2. Coxo-femoral Articulation ..... . 161 3. Femoro-tibial Articulation ..... 163 4. Tibio-fibular Articulation . . . . . .167 5. Articulations of the Tarsus, or Hock .... 168 Chapter III. — The Articulations in Birds ..... 172 Third Section. — The Muscles ....... 173 Chapter I. — General Considerations on the Striped Muscles . . . 174 The Striped Muscles in General . . . . , 174 X TABLE OF CONTENTS. Structure of the Striped Muscles . Physico-chemical Properties of the Striped Muscles Physiological Properties of the Striped Muscles Annexes of the Muscles xj Manner of Studying the Muscles . Chapter II. — The Muscles of Mammalia in Particular Article l. — The Muscles of the Trunk Subcutaneous Eegion .... Fleshy Panniculus Cervical Eegion ..... A. Superior Cervical or Spinal Region of the Neck 1. Rhomboideus ..... 2. Angularis Muscle of the Scapula 3. Splenius ...... 4. Great Complexus ..... 5. Small Complexus (Trachelo-mastoideus) . 6. Transverse Spinous Muscle of the Neck (Spinalis Colli) 7. Intertransversal Muscle of the Neck 8. Great Oblique Muscle of the Head (Obliquus Capitis Inferior) 9. Small Oblique Muscle of the Head (Obliquus Capitis Superior) 10. Great Posterior Straight Muscle of the Head . 11. Small Posterior Straight Muscle (Rectus Capitis Posticus Minor) B. Inferior Cervical or Trachelian Region .... 1. Subcutaneous Muscle of the Neck (Panniculus Carnosus^ . 2. Mastoido-humeralis (Levator Humeri). 3. Sterno-maxillaris ...... 4. Sterno-hyoideus ...... 5. Sterno-thyroideus . ..... 6. Omo-hyoideus, or Subscapulo-hyoideus 7. Great Anterior Straight Muscle of the Head (Rectus Capitis Anticus Major) .... 8. Small Anterior Straight Muscle of the Head iRectus Capitis Anticus Minor) ...... 9. Small Lateral Straight Muscle (Obliquus Capitis Aniicus) 10. Scalenus 11. Long Muscle of the Neck (Longus Colli) . Differential Charav'ters in the Muscles of the Cervical Region of other than Soliped Animals ...... A. Superior Cervical Region .... B. Inferior Cervical or Trachelian Region Spinal Region of the Back and Loins 1. Trapezius ...... 2. Great Dorsal (Latissimus Dorsi) 3. Small Anterior Serrated Muscle (Superficialis Costarum) 4. Small Posterior Serrated Muscle (Superficialis Costarum) 5. Ilio-spinalis Muscle (Longissimus Dorsi) 6. Common Intercostal Muscle (Transversalis Costarum) 7. Transverse Spinous Muscle of the Back and Loins (Spinalis and Semispinalis Dorsi 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 in Man with the analogous Muscles in the Domesticated Animals A. Muscles of the Back and Cervix . PAGE 178 180 181 183 183 186 186 186 186 187 187 188 189 189 191 191 193 193 193 194 195 195 195 196 196 198 198 198 198 199 199 199 200 200 201 201 201 203 203 203 205 205 206 208 209 209 209 210 TABLE OF CONTENTS. xxi PAGE B. Muscles of the Neck ....... 211 Sublumbar or In erior Lumbar Kegion . , , . 211 1. Iliac Fascia or Liimbo-iliac Aponeurosis . , . .212 2. Great Psoas Muscle ...... 212 3. Iliac Psoas Muscle (Iliacus) . . . . . .212 4. Small Psoas Muscle . . . . . .214 5. Square Muscle of the Loins (Sacro-lumbalis) . . . 214 6. Intertransverse Muscles of the Loins (Intertransversales Luml)oruni) 215 Differential Characters in the Muscles of the Sublumbar Eegion of other than Soliped Animals . . . . . . . 215 Comparison of the Sublumbar Muscles of Man with those of Animals . 215 Coccygeal Eegion. . . . . . . . 215 1. Sacro-coccygeal Muscles ..... 215 2. Ischio-coccygeus (Compressor Coccygeus) .... 217 Ptegion of the Head ....... 217 A. Facial Eegion ....... 217 1. Labialis (Orbicularis Oris) ..... 217 2. Alveolo-labialis (Buccinator) ..... 218 3. Zygomatico-labialis (Zygomaticus) .... 219 4. Lachrymo-labial, or Lachrymal Muscle .... 220 5. Supernaso-labialis (Levator Labii Superioris) . . 220 6. Supermaxillo-labialis (Nasalis Longus Labii Superioris) . . 220 7. Great Supermaxillo Nasalis (Dilatator Naris Lateralis) . 221 8. Small Supermaxillo-nasalis (Nasalis Brevis Labii Superioris) . 221 9. Transversalis Nasi (Dilatator Naris Anterior) . . . 221 10. Middle Anterior Muscle (Depressor Labii Superiori) . . 222 11. Maxillo-labialis (Depressor Labii Inferioris) . . . 222 12. Mento-labialis, or Muscle of the Chin .... 222 13. Middle Posterior Muscle (Levator Menti) . . .222 B. Masseterine or Temporo-maxillary Eegion .... 223 1. Masseter ....... 223 2. Temporal or Crotaphitic Muscle . . . . . 223 3. Internal Pterygoid (Pterygoideus Internus) . . . 224 4. External Pterygoid ...... 224 5. Digastricus . . . . . . . 225 c. Hyoideal Eegion ....... 225 1. Mylo-hyoideus ...... 225 2. Genio-hyoideus . . . . . . .226 3. Stylo-hyoideus (Hyoideus Magnus) .... 227 4. Kerato-hj^oideus (Hyoideus Parvus) .... 227 5. Occipito-styloideus ...... 227 6. Tranversalis Hyoidei ...... 228 Differential Characters in tbe Mjiscles of the Head of other than Soliped Animals ........ 228 A. Facial Eegion .....•• 228 B. Masseterine or Temporo-maxillary Eegion .... 229 V 0. Hyoid Eegion .....•• 230 Comparison of tbe Muscles of the Human Head with those of the Domes ticated Animals ....••• 230 A. Epicranial Muscles ...•••* ^30 B. Muscles of the Face ...••• 230 c. Muscles of the Lower Jaw ..•••• 231 D. Hyoid Muscles . . . . . • • 231 Axillary Eegion ....... • 231 [ TABLE OF CONTENTS, PAGE 1. Superficial Pectoral (Ptctoralis Transversus) . . . 231 2. Deep Pectoral ....... 233 Differential Characters in the Muscles of the Axillary Region of other than Soliped Animals ....... 235 Costal Kegion ....... 235 1. Great Serratus ....... 236 2. Transverse Muscle of the Eibs (Lateralis Sterni) . . 236 3. External Intercostals ...... 237 4. Internal Intercostals ...... 237 5. Supercostals (Levatores Costarum) ..... 237 6. Triangularis of the Sternum (Sterno-coistales) . . . 237 Differential Characters in the Muscles of the Costal Region of other than Soliped Animals ....... 238 Comparison of the Thoracic Muscles of Man with those of the Domesticated Animals . . . . . . . . 238 Inferior Abdominal Region . . . . . .238 1. Abdominal Tunic ...... 239 2. White Line. . . . . . . .240 3. Great or External Oblique of the Abdomen . . . 240 4. Small or Internal Oblique of the Abdomen .... 24li 5. Great Rectus Muscle of the Abdomen . . . .243 6. Transverse Muscle of the Abdomen ..... 244 Differential Characters in the Muscles of the Abdominal Region of other than Soliped Animals ...... 245 Comparison of the Abdominal Muscles of Man with those of Animals . 245 Diaphragmatic Region ...... 246 Diaphragm ........ 246 Differential Characters in the Diaphragm of other than Soliped Animals 248 Comparison of the Diaphragm of Man with that of Animals . . 248 Article ii. — Muscles of the Anterior Limbs ..... 248 Muscles of the Shoulder . . . . . .249 A. External Scapular Region ...... 249 1. External Scapular Aponeurosis . . . . . 249 2. Long Abductor of the Arm, or Scapular portion of the Deltoid (Teres Major) . . . . . . . .249 3. Short Abductor of the Arm, or Teres Minor . . . 250 4. Superspinatus (Antea Spinatus) . . . . . 251 5. Subspinatus (Postea Spinatus) . . . . .251 B. Internal Scapular Region ...... 252 1. Subscapularis ....... 252 2. Adductor of the Arm, or Teres Major .... 253 3. Coraco-humeralis, Coraco-brachialis, or Omo-brachialis . . 254 4. Small Scapulo-humeralis . , . . . . . 254 Differential Characters in the Muscles of the Shoulder of other than Soliped Animals . . * . . . . . . 254 Comparison of the Muscles of the Shoulder of Man with those of Animals . 255 Muscles of the Arm . . . . . . . 255 A. Anterior Brachial Region .... . 255 1. Long Flexor of the Fore-arm, or Brachial Biceps (Flexor Brachiij 255 2. Short Flexor of the Fore-arm (Humeralis Externus) . . 256 B. Posterior Brachial Region ...... 258 1. Long Extensor of the Fore -arm (Caput Magnum) . . 258 2. Large Extensor of the Fore-arm (Caput Magnum) . . .258 3. Short Extensor of the Fore arm (Caput Medium) . . 259 TABLE OF CONTENTS. xxiii PAGE 4. Middle Extensor of the Fore-arm (Caput Parvum) . . 259 5. Small Extensor of the Fore-arm, or Anconeus . . . 260 Diiferential Characters in the Muscles of the Arm of other than Soliped Animals ........ 260 Comparison of the Muscles of the Arm of Man with those of Animals . 260 Muscles of the Fore-arm ...... 261 Antibrachial Aponeurosis ..... . , 261 A. Anterior Antibrachial Region ..... 262 1. Anterior Extensor of the Metacarpus (Extensor Metacarpi Magnus) 262 2. Oblique Extensor of the Metacarpus (Extensor Metacarpi Ol)li juus) 263 3. Anterior Extensor of the Phalanges (Extensor Pedis ) . .263 4. Lateral Extensor of the Phalanges (Extensor Suffraginis) . 264 B. Posterior Antibrachial Eegion ..... 265 1. External Flexor of the Metacarpus, or Posterior Ulnaris. . 265 2. Oblique Flexor of the Metacarpus, or Anterior Ulnaris (Flexor Metacarpi Medius) ...... 266 3. Internal Flexor of the Metacarpus, or Palmaris Magnus (Flexor Metacarpi Internus) ..... 266 4. Superficial Flexor, Sublimis of the Phalanges, or Perforatus . 267 5. Deep Flexor of the Phalanges, or Perforans . . . 268 Differential Characters in the Muscles of the Fore-arm of other than Soliped Animals ........ 270 Muscles proper to the Fore-arm in Carnivora .... 272 1. Proper Extensor of the Thumb and Index .... 272 2. Long Supinator. ...... 272 3. Short Supinator . . . . . . .274 4. Round Pronator ...... 274 5. Square Pronator ....... 274 Comparison of the Muscles of the Fore-arm of Man with those of Animals 274 A. Anterior Region . . . . • . • 274 B. External Region . - . ♦ . • . 276 c. Posterior Region ....... 276 Muscles of the Anterior Foot or Hand . . . , . 276 A. Muscles of the Anterior Foot in Carnivora . . . .276 1. Short Abductor of the Thumb ..... 276 2. Opponens of the Thumb . . a , . . 277 3. Short Flexor of the Thumb , .... 277 4. Adductor of the Index ...... 277 5. Cutaneous Palmar k Palmaris Brevis) . • • . 277 6. Adductor of the Small Digit . . , • .277 7. Short Flexor of the Small Digit .... 277 8. Opponens of the Small Digit . . . . .277 9. Lumbrici ....... 278 10. Metacarpal Interosseous Muscles . . o . . 278 B. Muscles of the Anterior Foot in the Pig . - . . 278 c. Muscles of the Anterior Foot in Solipeds .... 278 D. Muscles of the Anterior Foot in Ruminants . . . 279 Comparison of the Hand of Man with that of Animals . . . 279 A. Muscles of the Thenar Eminence ..... 279 B. Muscles of the Hypothenar Eminence. .... 279 c. Interosseous Muscles . . . . . . 279 Article in.— Muscles of the Posterior Limbs .... 280 Muscles of the Gluteal Region, or Croup .... 280 1. Superficial Gluteus (Gluteus Externus) .... 280 TABLE OF CONTENTS. PAGE 2. Middle Gluteus (Gluteus Maximus) . . . . 281 3. Deep Gluteus (Gluteus Internus) ..... 282 Differential Characters in the Muscles of the Gluteal Eegion of other than Soliped Animals ....... 283 Comparison of the Gluteal Muscles of Man with those of Animals . . 283 Muscles of the Tliigh ...... 283 A. Anterior Crural, or Femoral Region ..... 283 1. Muscle of the Fascia Lata (Tensor Vaginae) . . . 284 2. Crural Triceps . . . . , . .284 3. Anterior Gracilis (Crureus vel Cruralis). . . . 285 B. Posterior Crural Region ...... 286 1. Long Vastus (Biceps Abductor Femoris) . . . 286 2. Semitendinosus Muscle (Adductor Tibialis) . . . 287 3. Semimembranosus (Adductor Tibialis) .... 288 C. Internal Crural Region ...... 288 1. Long Adductor of the Leg (Sartorius) .... 288 2. Short Adductor of the Leg (Gracilis) . . . .289 3. Pectineus . . . . . . .289 4. Small Adductor of the Thigh (Adductor Femoris) . . .291 5. Great Adductor of the Thigh (Adductor Longus) . . 291 6. Square Crural (Quadratus Femoris). . . . . 292 7. External Obturator ...... 292 8. Internal Obturator . . . . . . .292 9. Gemelli of the Pelvis (Gemini) ..... 293 Differential Characters in the Muscles of the Thigh of other than Soliped Animals ........ 294 A. Anterior Crural Region ...... 294 B. Posterior Crural Region . . . . . . 294 0. Internal Crural Region ...... 295 Comparison of the Muscles of Man's Thigh with those of the Thigh of Animals ........ 295 A. Anterior Muscles ....... 295 B. Muscles of the Posterior Region . . . . .295 c. Muscles of the Internal Region . = . . . 296 Muscles of the Leg . . . . . . .297 Tibial Aponeurosis ....... 297 A. Anterior Tibial Region ...... 298 1. Anterior Extensor of the Phalanges (Extensor Pedis) . . 298 2 Lateral Extensor of the Piialanges (Peroneus) . . . 298 3. Flexor of the Metatarsus ..... 300 B. Posterior Tibial Region ...... 302 1. Gastrocnemii, or Gemelli of the Tibia (Gastrocnemius Externus) 302 2. Soleus, or Solearis (Plantaris) ..... 304 3. Superficial Flexor of the Phalanges, or Perforatus (Gastrocnemius Internus) ........ 304 4. Popliteus ....... 304 5. Deep Flexor of the Phalanges, or Perforans (Flexor Pedis) . . 305 6. Oblique Flexor of the Phalanges (Flexor Pedis Accessorius) . 306 Differential Characters in the Muscles of the Leg of other than Soliped Animals .... ... 306 A. Anterior Tibial Region . . . . . . 306 B. Posterior Tibial Region . . . . . • -^09 Comparison of the Muscles of the Leg of Man with those of Animals . 309 A. Anterior Region . . . . . . • 309 TABLE OF CONTENTS. xxv PAGE B. External Region . . . . . . . 309 c. Posterior Region ....... 309 Muscles of the Posterior Foot . . . . .311 Comparison of the Muscles of the Foot of Man with those of Animals . 311 A. Dorsal Region . . . . . . .311 B. Plantar Region . . . . . . .312 c. Interosseous Muscles ...... 313 Chapter III.— The Muscles in Birds . ..... 313 Chapter IV. — General Table of tlie insertions of the Muscles in Solipeds . 315 BOOK 11. THE DIGESTIVE APPARATUS. Chapter I. — General Considerations on the Digestive Apparatus , . 325 Chapter II. — The Digestive Apparatus in Mammalia .... 330 Article i.— Preparatory Organs ot the Digestive Apparatus . . 330 The Mouth . . . . . . . . 330 1. Lips ........ 330 2. Cheeks ........ 332 3. Palate ........ 332 4. Tongue . . . . . . . .334 5. Soft Palate ....... 340 6. Teeth . . . . . . . .344 7. The Mouth in General ...... 355 Differential Characters in the Mouth of other than Soliped Animals . 356 Comparison of the Mouth of Man with that of Animals . . 362 The Salivary Glands . . . . . . .364 1. Parotid Gland ....... 365 2. Maxillary, or Submaxillary Gland ..... 367 3. Sublingual Gland ...... 369 4. Molar Glands . . . . . . .369 5. Labial, Lingual, and Palatine Glands .... 370 Differential Characteis in the Salivary Glands of other than Soliped Animals . . . . . . . . .370 Comparison of the Salivary Glands of Man witb those of Animals . 372 The Pharynx ........ 372 Differential Characters in the Pharynx of other than Soliped Animals . 376 Comparison of the Pharynx of Man with that of Animals . . . 377 The (Esophagus ....... 377 Differential Characters in the CEsophagus of other than Soliped Animals . 380 Comparison of the CEsophagus of Man with that of Animals . . 380 Article ii. — The Essential Organs of Digestion .... 380 The Abdominal Cavity . . . . . .380 Differential Characters in the Abdominal Cavity of other than Soliped Animals ........ 384 Comparison of the Abdominal Cavity of Man with that of Animals . 385 The Stomach . . . . . . ... 385 1. The Stomach of Solipeds ..... 385 Differential Characters in the Stomach of other than Soliped Animals . 393 1. The Stomach of the Pig ..... 393 2. The Stomach of Carnivora ...... 393 3. The Stomach of Ruminants ..... 393 Comparison of the Stomach of Man with that of Animals . . . 400 xvi TABLE OF CONTENTS. PAGE The Intestines ....... 400 1. The Small Intestine . . . . . .400 2. The Large Intestine . . . . . . 407 A. Csecum ........ 407 B. Colon . . . . . . . . 410 c. Rectum ........ 413 Differential Characters in the Intestines of other than Soliped Animals . 414 1. The Intestines of Ruminants ..... 414 2. The Intestines of the Pig . . . . .416 3. The Intestines of Carnivora ....'. 416 Comparison of the Intestines of Man with those of Animals . , 417 General and Comparative Survey of the Abdominal or Essential Portion of the Digestive Canal ....... 418 Organs Annexed to the Abdominal Portion of the Digestive Canal . 419 1. Liver ........ 419 2. Pancreas ....... 427 3. Spleen ........ 428 Differential Characters in the Organs Annexed to the Abdominal Portion of the Digestive Canal in other than Soliped Animals . . 432 Comparison of the Organs Annexed to the Abdominal Portion of the Digestive Canal of Man with those of Animals ..... 434 Chapter III. — The Digestive Apparatus of Birds .... 435 BOOK III. EESPIEATORY APPARATUS. Chapter I. — Respiratory Apparatus in Mammalia . . • . 439 The Nasal Cavities ,,..... 439 1. The Nostrils . , , . . . .440 2. The Nasal Fossae ...... 441 3. The Sinuses . . .. . . . .446 Differential Characters in the Nasal Cavities of other than Soliped Animals 448 Comparison of the Nasal Cavities of Man with those of Animals . 449 Tiie Air-tube succeeding the Nasal Cavities ..... 449 1. The Larynx ....... 449 2. The Trachea . . . . . . .457 3. The Bronchi ....... 460 Differential Characters in the Air-tube succeeding the Nasal Fossae of other than Soliped Animals .,...• 461 Comparison of the Larynx and Trachea of Man with these Organs in the Domesticated Animals ...... 462 The Thorax ....... ^ 462 Differential Characters in the Thorax of other than Soliped Animals 466 The Lungs ........ 466 Differential Characters in tiie Lungs of other than Soliped Animals . 470 Comparison of the Larynx, Trachea, and Lungs of Man with the same Organs in Animals . . . . . .471 The Glandiform Bodies connected with the Respiratory Apparatus . 472 1. The Thyroid Body , . . . . . .472 2. The Thymus Gland . ... . '. .473 Differential Characters in the Glandiform Bodies annexed to the Respiratory Apparatus of other than Soliped Animals .... 474 TABLE OF CONTENTS. xxvii PAGE Comparison of the Glandiform Bodies annexed to the Eespiratory Apparatus in Man with those of Animals ..... 475 Chapter II.— The Respiratory Apparatus of Birds . • • . 475 BOOK IV. URINARY APPARATUS. 1. The Kidneys » . 484 2. The Ureters ........ 490 3. The Bladder ....... 491 4. The Urethra ........ 493 5. The Suprarenal Capsules ...... 494 Differential Characters of the Urinary Apparatus in other than Soliped Animals ........ 495 Comparison of the Urinary Apparatus of Man with that of Animals . 496 BOOK V. CIRCULATORY APPARATUS. EiEST Section. — The Heart . . . . . 1. The Heart as a Whole ..... 2. External Conformation of the Heart 3. 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 Animals Comparison of the Heart of Man with that of Animals Second Section. — The Arteries ..... Chaptee I. — General Considerations . . . Chapter II. — Pulmonary Artery ..... Chapter III. — Aorta ....... Article i.— Common Aorta, or Aortic Trunk Cardiac, or Coronary Arteries .... Article ii. — Posterior Aorta ..... Parietal Branches of the Posterior Aorta . 1. Intercostal Arteries ..... 2. Lumbar Arteries ..... 3. Diaphragmatic Arteries .... 4. Middle Sacral Artery .... Visceral Branches of the Posterior Aorta 1. Broncho-CEsophageal Trunk . . 2. C celiac Artery ...... 3. Great Mesenteric Artery .... 4. Small Mesenteric Artery .... 5. Eenal, or Emulgent Arteries 6. Spermatic Arteries ...... 7. Small Testicular Arteries (Male), Uterine Arteries (Female) Differential Characters in the Posterior Aorta and its Collateral Branches other than Soliped Animals ..... 1. Posterior Aorta iu Kuminants .... 2. Posterior Aorta in the Pig ..... 3. Posterior Aorta in Carnivora .... Comparison of the Aorta of Man with that of Animals , of 499 499 500 503 507 512 513 513 5H 515 515 521 522 522 523 523 525 525 526 526 526 526 526 527 529 532 534 534 535 535 535 537 537 538 iii TABLE OF CONTENTS. PAGE Article in. — Internal Iliac Arteries, or Pelvic Trunks . , . 538 1. Umbilical Artery ....... 538 2. Internal Pudic, or Bulbous Artery ..... 540 3. Subsacral, or Lateral Sacral Artery . . . .540 4. Iliaco-muscular, or Ilio-lumbar Artery . . . .541 5. Gluteal Artery . . . . . . .542 6. Obturator Artery . . . . , . .542 7. Iliaco-femoral Artery . . . . . . 543 Dififerential Characters in the Internal Iliac Arteries of otlier than Solipcd Animals ........ 543 1. Internal Iliac Arteries of Euminants . . . . 543 2. Internal Iliac Arteries of the Pig ..... 544 3. Internal Iliac Arteries of the Carnivora .... 544 Comparison of the Internal Iliac Arteries of Man with those of Animals . 545 Article iv. — External Iliac Arteries, or Crural Trunks . . . 545 Femoral Artery ........ 547 1. Prepubic Artery ...... 547 2. Deep Femoral, Deep Muscular, or Grreat Posterior Muscular Artery of the Thigh . . . . . . .548 3. Superficial Muscular, or Great Anterior Muscular Artery . 548 4. Innominate Muscular, or Small Muscular Arteries . . . 549 5. Saphena Artery ...... 549 Popliteal Artery ........ 549 Terminal Branches of the Popliteal Artery .... 550 1. Posterior Tibial Artery . . . ... . 550 2. Anterior Tibial Artery . . . . .551 3. Pedal Artery . . . . . . .551 Differential Characters in the External Iliac Arteries of other than Soliped Animals ........ 555 1. External Iliac Arteries of Euminants .... 555 2. External Iliac Arteries of the Pig .... 556 3. External Iliac Arteries of Carnivora .... 556 Comparison of the External Iliac Arteries of Man with those of Animals 557 Article v. — Anterior Aorta ...... 559 Article vi. — Axillary Arteries, or Brachial Trunks .... 559 Collateral Branches of the Axillary Arteries .... 560 1. Dorsal, Dorso-muscular, or Transverse Cervical Artery . . 560 2. Superior Cervical, Cervico-muscular, or Deep Cervical Artery . 561 3. Vertebral Artery ....... 561 4. Internal Thoracic, or Internal Mammary Artery . . 563 5. External Thoracic, External Mammary, or Inferior Thoracic Artery 563 6. Inferior Cervical Artery ..... 564 7. Superscapular Artery . . . . . . 564 8. Subscapular Artery ...... 564 Terminal Branch of the Brachial Trunk, or Humeral Artery . . 565 1. Anterior Kadial Artery ...... 566 2. Posterior Kadial Artery ...... 567 1. First Terminal Branch of the Posterior Eadial Artery, or Common Trunk of the Interosseous Metacarpals . . . ^^^ 2. Second Terminal Branch of the Posterior Kadial Artery, or Colla- teral Artery of the Canon . . . . • 569 Differential Characters in the Axillary Arteries of Non-soliped Animals 570 1. Axillary Arteries of Euminants ..... 570 2. Axillary Arteries of the Pig . ... . . 572 TABLE OF CONTENTS. 3. Axillary Arteries of CarniYora . Comparison of the Axillary Arteries of Man with those of Animals Article vii. — Common Carotid Arteries Occipital Artery ..... Internal Carotid Artery .... External Carotid Artery ..... 1. External Maxillary, Facial, or Glosso-Facial Artery 2. Maxillo-Muscular Artery , . . . 3. Posterior Auricular Artery 4. Superficial Temporal Artery, or Temporal Trunk 5. Internal Maxillary, or Gutturo-maxillary Artery Differential Characters in the Carotid Arteries of Non-soliped Animals 1. Carotid Arteries of Carnivora . 2. Carotid Arteries of the Pig . 3. Carotid Arteries of Euminants . Comparison of the Carotid Arteries of Man with those of Animals Third Section. — The Veins .... Chapter I. — General Considerations .... Chaptee II. — Veins of the Lesser Circulation, or Pulmonary Veins Chapter III. — Veins of the General Circulation Article i. — Cardiac, or Coronary Veins . Article ii. — Anterior Vena Cava .... Jugular Veins .... Roots of the Jugular .... 1. Superficial Temporal Vein 2. Internal Maxillary Vein 3. The Sinuses of the Dura Mater . Axillary Veins ..... 1. Subscapular Vein 2. Humeral Vein .... 3. Spur, or Subcutaneous Thoracic Vein . 4. Deep Veins of the Fore-arm 5. Superficial Veins of the Foi-e-arm 6. Metacarpal Veins .... 7. Digital Veins .... 8. Veins of the Foot, or Ungual Region a. External Venous Apparatus . h. Internal, or Intra-osseous Venous Apparatus Article iii. — Posterior Vena Cava Diaphragmatic Veins .... Vena Portse ..... 1. Roots of the Vena Portss 2. Lateral Affluents of the Vena Portse Renal Veins . . . • . Spermatic Veins .... Lumbar Veins . . . Common Iliac Veins, or Pelvi-crural Trunks 1. Internal Iliac Vein .... 2. External Iliac Vein 3. Femoral Vein . 4. Popliteal Vein .... 5. Deep Veins of the Leg 6. Superficial Veins of the Leg 7. Metatarsal Veins .... 8. Veins of the Digital Region XXIX PAGE 572 574 575 577 579 581 581 585 585 585 586 590 590 591 592 595 596 596 599 599 599 600 601 , 603 603 , 605 605 . 609 610 . 610 610 . 610 611 . 611 612 . 612 612 . 616 617 . 617 617 . 620 621 . 621 621 . 622 622 . 622 623 . 623 623 . 623 624 . 624 625 XXX TABLE OF CONTENTS. PAGE Differential Cliaracters in the Veins of other than Soliped Animals . . 625 Comparison of the Veins of Man with those of Animals . . 626 FouETH Section. — The Lymphatics ...... 627 Chapter T. — General Considerations , . . , , 627 Lymphatic Vessels ....... 627 Lymphatic Glands, or Ganglia ..... 632 Chapter IL — The Lymphatics in Particular ..... 634 Article i. — The Thoracic Duct ...... 634 Article ii. — The Lymphatics which constitute the Affluents of the Thoracic Duct ......... 637 Lymphatics of the Abdominal Limb, Pelvis, Abdominal Parietes, and Pelvi-inguinal Organs . . . . . . 638 1. Sublumbar Glands ....... 638 2. Deep Inguinal Glands ...... 638 3. Superficial Inguinal Glands . . , , , 638 4. Popliteal Glands ...... 640 5. Iliac Glands ....... 640 6. Precrural Glands ...... 640 Lymphatics of the Abdominal Viscera ..... 640 1. Glands and Lymphatic Vessels of the Kectum and Floating Colon 640 2. Glands and Lymphatic Vessels of the Large Colon . . 641 3. Glands and Lymphatic Vessels of the Caecum . . . 641 4. Glands and Lymphatic Vessels of the Small Intestine . . 641 5. Glands and Lymphatic Vessels of the Stomach . . . 641 6. Glands and Lymphatic Vessels of the Spleen and Liver . . 642 Glands and Lymphatic Vessels of the Organs contained in the Thoracic Cavity . . . . . . . .642 Glands and Lymphatic Vessels of the Thoracic Parietes . . 642 Lymphatic Vessels of the Head, Neck, and Anterior Limb . . 643 1. Prepectoral Glands ...... 643 2. Pharyngeal Glands ....... 643 3. Submaxillary, or Subglossal Glands . . . . 644 4. Prescapular Glands • . . » . . 644 5. Brachial Glands ...... 644 Article iii. — Great Lymphatic Vein ...... 644 Differential Characters in the Lymphatics of N"on-soliped Animals . 645 Chapter III. — The Circulatory Apparatus in Birds .... 647 Article i. — The Heart ....... 647 Article ii. — The Arteries ....... 648 Article iii. — The Veins ....... 649 Article rv. — The Lymphatics ...... 649 BOOK YI. APPARATUS OF INNERVATION. First Section. — The Nervous System in General .... 650 General Conformation of the Nervous System . . . .651 Structure of the Nervous System ..... 652 Properties and Functions of the Nervous Systems . . . 655 Second Section.— The Central Axis of the Nervous System . . .659 Chapter I. — Protective and Enveloping Parts of the Cerebro- spinal Axis 659 The Bony Case which lodges the Central Cerebro-spinal Axis . 659 1. The Spinal Canal . . . . . . .659 2. The Cranial Cavity ...... 660 TABLE OF CONTENTS. xxxi PAGE The Envelopes of the Oerebro-spinal Axis .... 660 1. The Dura Mater ...... 661 2. The Arachnoid . . . . . . .663 3. The Pia Mater . . . ' . . . . 665 Differential Characters in the Protecting and Enveloping Parts of the Cerebro-spinal Axis in other than Soliped Animals . . . 666 Comparison of the Protective and Enveloping Parts cf the Cerebro-spinal Axis of Man with those of Animals .... 666 Chapter II.— The Spinal Cord . . ... . . .666 External Conformation of the Spinal Cord .... 666 Internal Conformation and Structure of the Spinal Cord . . . 668 Differential Characters in the Spinal Cord of the Domesticated Mammals other than Solipeds ...... 672 Comparison of the Spinal Cord of Man with that of Animals . . 672 Chapter III. — The Encephalon ...... 672 Article i. — The Encephalon as a Whole ..... 672 Ai'ticle II. — The Isthmus ....... 675 External Conformation of the Isthmus ..... 675 1. The Medulla Oblongata ..... 676 2. The Pons Varolii . . . . . . .677 3. The Crura Cerebri ...... 677 4. The Crura Cerebelli . . . . . .678 5. The Valve of Vieussens ...... 679 6. The Corpora Quadrigemina, or Bigemina .... 679 7. The Optic Thalami ...... 679 8. The Pineal Gland . . . . . . .680 9. The Pituitary Gland ...... 681 Internal Conformation of the Isthmus ..... 682 1. The Middle Ventricle, or Ventricle of the Optic Thalami . 682 2. The Aqueduct of Sylvius . . . . . . 683 3. The Posterior, or Cerebellar Ventricle .... 683 Structure of the Isthmus ....... 683 Differential Characters in the Isthmus of other than Soliped Animals . 685 Comparison of the Isthmus of Man with that of Animals . . . 685 Article iir. — The Cerebellum ...... 686 1. External Conformation of the Cerebellum .... 686 2. Internal Conformation of the Cerebellum . . . 688 Differential Characters of the Cerebellum in other than Soliped Animals . 689 Comparison of the Cerebellum of Man with that of Animals . . 689 Article IV.— The Cerebrum . . . . . . .689 External Conformation of the Cerebrum .... 690 1. The Longitudinal Fissure ....... 690 2. The Cerebral Hemispheres . . . . .691 Internal Conformation of the Brain ..... 692 1. The Corpus Callosum ...... 693 2. The Lateral, or Cerebral Ventricles .... 693 3. The Septum Lucidum ...... 694 4. The Cerebral Trigonum (or Fornix) ... 694 5. The Hippocampi ...... 695 6. The Corpora Striata . . . . , 695 7. The Cerebral Choroid Plexus, and Velum Inteipositum . . 696 Structure of the Cerebrum ...... 697 Differential Characters in the Brain of other than Soliped Animals . 698 Comparison of the Brain of Man with that of Animals , . . 698 xxxii TABLE OF CONTENTS. PAGK Third Section. — The Nerves .... . 700 Chapter I. — The Cranial, or Encephalic Nerves .... 70B 1. First Pair, or Olfactory Nerves ..... 705 2. Second Pair, or Optic Nerves . .... 7OG 3. Third Pair, or Common Motor Ocular Nerves . . . 7O8 4. Fourth Pair, or Pathetici Nerves ..... 709 5. Fifth Pair or Trigeminal Nerves . . . . .710 6. Sixth Pair, or External Motor Ocular Nerves . . . .721 7. Seventh Pair, or Facial Nerves . . . . .721 8. Eighth Pair, or Auditory, or Acoustic Nerves .... 727 9. Ninth Pair, or Glosso-Pharyngeal Nerves .... 727 10. Tenth Pair, Vagus, or Pneumogastric Nerves . . . 728 11. Eleventh Pair, Spinal, or Accessory Nerves of the Pneumogastrics 736 12. Twelfth Pair, or Great Hypoglossal Nerves . . . 738 Differential Characters in the Cranial Nerves of other than Soliped Animals 739 Comparison of the Cranial Nerves of Man with those of Animals . . 744 Chapter II. — Spinal Nerves ...... 747 Article i. — Cervical Nerves (Eight Pairs) ..... 748 Article 11. — Dorsal Nerves (Seventeen Pairs) .... 750 Article in. — Lumbar Nerves (Six Pairs) ..... 751 Article iv.— Sacral Nerves (Five Pairs) ..... 752 Article v. — Coccygeal Nerves (Six to Seven Pairs) .... 753 Article vi. — Composite Nerves formed by the Inferior Ramuscules of the Spinal Branches ........ 753 Diaphragmatic Nervts ....... 754 Brachial Plexus ....... 754 1. Diaphragmatic Branches ...... 755 2. Branch to the Angukris and Rhomboideus . . . 755 3. Branch to the Serratus Magnus, or Superior Thoracic . . 756 4. Branches to the Pectoral Muscles, or Inferior Thoracic . . 756 5. Subcutaneous Thoracic Branch . , . . . 756 6. Branch to the Great Dorsal ..... 758 7. Axillary, or Circumjflex Nerve ..... 758 8. Nerve of Adductor of tiie Arm, or Teres Major . . . 758 9. Subscapular Branches ...... 758 10. Superscapular Nerve ...... 758 11. Anterior Brachial Nerve ...... 758 12. Radial Nerve ....... 759 13. Ulnar, or Cubito-cutaneous Nerve ..... 760 14. Median, or Cubito-plantar Nerve .... 760 Dilferential Characters in the Brachial Plexus of other than Soliped Animals ........ 763 Comparison of the Brachial Plexus of Man with that of Animals . 767 Sacro-lumbar Plexus ....... 770 1. Iliaco-muscular Nerves ...... 772 2. Crural, or Anterior Femoral Nerve ..... 772 3. Obturator Nerve ...... 772 4. Small Sciatic, or Anterior and Posterior Gluteal Nerves . . 773 5. Great Sciatic, or Great Femoro-popliteal Nerve . . . 774 Collateral Branches ....... 775 Terminal Branches ....... 777 Differential Characters in the Sacro-lumbar Plexus of other than Soliped Animals . . . . . . . .777 Comparison of the Sacro-lumbar Plexus of IMan with that of Animals . 778 TABLE OF CONTENTS. Chapter III. — The Great Sympathetic .... 1. Cephalic Portion of the Sympathetic Chain . 2. Cervical Portion of the Sympathetic Cliain 3. Dorsal Portion of the Sympathetic Chain 4. Lumbar Portion of the Sympathetic Chain 5. Sacral Portion of the Sympathetic Chain Differential Characters in the Great Sympathetic of other than Animals ...... Comparison of the Great Sympathetic of Man with that of Animals Chapter IV.— The Nervous System of Birds Soliped PAG I-: 781 782 783 786 788 788 789 783 790 BOOK YII. APPARATUS OF SENSE. Chapter I.— Apparatus of Touch . Article i. — Of the Skin Proper Article ii. — The Integumentary Appendages The Hair .... Horny Productions .... 1. TheHoofofSolipeds a. The Parts contained in the Hoof h. Description of the Hoof . 2. The Claws of Ruminants and Pachyderms 3. The Claws of Carnivora 4. The Frontal Horns 5. The Chesnuts (6. Tlie Ergots . . . , Chapter II. — Apparatus of Taste Differential Characters in the Apparatus of Taste of other than Soliped Animals . . . . . . Comparison of the Apparatus of Taste in Man with that of Animals Chapter III. — Apparatus of Smell . Chapter IV.— Apparatus of Vision Article i. — Essential Organ of Vision, or Globe of the Eye Membranes of the Eye . 1. The Sclerotica . 2. The Transparent Cornea 3. The Choroid Membrane 4. The Iris 5. The Retina The Humours of the Eye 1. Crytetalline Lens 2. Vitreous Humour . 3. Aqueous Humour Article ii.— Accessory Organs of the Apparatus of Vision Orbital Cavity .... Motor Muscles of the Globe of the Eye . Protective Organs of the Eye 1. Eyelids ..... 2. Membrana Nictitans Lachrymal Apparatus .... Differential Characters in the Vi^-ual Apparatus of other than Animals . . . . . Comparison of the Visual Apparatus of Man with that of Animals 3 Soliped 792 792 797 797 799^ 800 800 805 812 812 813 813 813) 813 815 815 815 816 817 817 817 819 820 822 824 826 826 827 827 828 828 828 830 830 833 834 835 836 TABLE OF CONTENTS. Chapter V. —Apparatus of Hearing ..... 837 Article i. — Internal Ear, or Labyrinth . . , . . 837 Bony Labyrinth . . . . o . . 837 1. The Vestibule . . . . . , .837 2. The Semicircular Canals ..... 837 3. The Cochlea . . . , , . .837 The Membranous Labyrinth ...... 838 1. The Membranous Vestibule . . . . . 838 2. The Membranous Semicircular Canals .... 839 3. The Membranous Cochlea ...... 839 Liquids of the Labyrinth ...... 840 Distribution and Termination of the Auditory Nerve in the Membranous Labyrinth . . . . . . . .840 Article ii. — Middle Ear, or Case of the Tympanum . . . 840 1. Membrane of the Tympanum ..... 841 2. The Promontory, Fenestra Ovalis, Fenestra Rotunda . . 842 3. The Mastoid Cells . . . . . . .842 4. Chain of Bones of the Middle Ear .... 842 5. Mucous Membrane of the Tympanic Case . . . . 844 6. Eustachian Tube ...... 844 7. Guttural Pouches . . . . „ . . 844 Article iii.— The External Ear ...... 846 External Auditory Canal ...... 846 The Concha, or Pavilion ..,„.. 846 1. Cartilaginous Basis of the Concha . . t . . 846 2. Muscles of the External Ear ..... 847 3. Adipose Cushion of the External Ear .... 850 4. Integuments of the External Ear .... 850 Differential Characters in the Auditory Apparatus of other than Soliped Animals ........ 850 Comparison of the Auditory Apparatus of Man with that of Animals . 850 BOOK VIII. GENERATIVE APPAEATUS. Chapter I. — Genital Organs of the Male The Testicles, or Secretory Organs of the Semen . 1. Description of the Vaginal Sheath 2. Description of the Testicles ... Excretory Apparatus for the Semen . 1. The Epididymis and Deferent Duct 2. The Vesiculse Seminales and 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 Mammals ...... Comparison of the Genital Organs of Man with those of Animals Chapter II. — Genital Organs of the Female 1. The Ovaries ....... 2. The Uterine Cornua, Fallopian Tubes, or Oviducts 3. The Uterus ....... Soliped 851 851 852 853 858 858 860 861 864 864 865 867 871 872 872 876 877 TABLE OF CONTENTS. xxxv PAGE 4. The Vagina . , ..... 880 5. The Vulva . 882 6. The Mammae ... .... 884 Differential Characters in the Female Genital Organs of other than Soliped Mammals ........ 886 Comparison of the Genital Organs of Woman with those of Domesticated Female Animals ....... 888 Chaptee III. — Generative Apparatus of Birds .... 889 1. Male Genital Organs . . . . . . .889 2. Female Genital Organs ...... 889 BOOK IX. EMBRYOLOGY. Chapter I. — The Ovum and its Modifications after Impregnation . . 890 Article I.— The Ovum ....... 890 Article ii.— Modifications in the Ovum until the Appearance of the Embryo . 890 Article in. — Development of the Blastodermic Laminse . . . 892 External Lamina ........ 893 Middle Lamina ....... 893 Internal Lamina . . ..... 894 Chapter II. — The Foetal Envelopes of Solipeds . , . 895 1. The Chorion . . ..... 895 2. The Amnion ....... 896 3. The Allantois . . . . . . , .896 4. The Umbilical Vesicle ...... 899 5. The Placenta ........ 899 6. The Umbilical Cord ....... 900 Differential Characters in the Annexes of the Foetus of other Domesticated Animals than Solipeds ...... 901 Comparison of the Annexes of the Human Foetus with those of the Foetus of Animals ........ 904 Chapter III.— Development of the Foetus . . . . .905 Article i. — Formation of the Embryo ..... 905 Development of the Chorda Dorsalis and Vertebral Laminse . . 905 Development of the Lateral and Cephalic Laminse . . . 905 Article ii.— Development of the Various Organs of the Animal Economy . 907 Development of the Nervous System ..... 907 Development of the Organs of Sense ..... 908 Development of the Locomotory Apparatus . . . .911 Development of the Circulatory Apparatus > ^ . .914 Development of the Respiratory Apparatus .... 918 Development of the Digestive Apparatus . . . . .919 Development of the Genito-urinary Apparatus . ... 922 Chapter IV.— The Ovum of Birds . . . . , .925 Index . . . e c . . o > 927 TABLE OF ILLUSTRATIONS. FIGS. 1. Skeleton of the Dog .... 2. Skeleton of the Pig . . . 3. Skeleton of the Horse 4. Skeleton of the Cow 5. Skeleton of the Sheep .... 6. Vertical section of bone . 7. Minute structure of bone 8. Lacunae, or osteoplasts of osseous substance 9. Cartilage at the seat of ossification 10. Elements of a vertebra 11. Atlas, inferior surface 12. A cervical vertebra 13. The axis or dentata, lateral view 14. Type of a dorsal vertebra, the fourth 15. Upper surface of lumbar vertebrae 16. Lumbar vertebra, front view 17. Lateral view of sacrum 18. Horse's head, front view . 19. Anterior bones of the head of a foetus at birth 20. Posterior bones of the head of a foetus at birth 21. Posterior aspect of Horse's skull 22. Antero-posterior and vertical section of the Horse's 23. Longitudinal and transverse section of the Horse's 24. Inferior maxilla .... 25. Hyoid bone . . . . , 26. Lateral view of the Horse's skull 27. Ox's head, anterior aspect 28. Kam's head, anterior aspect 29. Ox's head, posterior aspect 80. Median and vertical section of the Ox's head 31. Head of the Pig, anterior aspect 82. Head of the Pig, posterior aspect . 33. Head of Dog, anterior aspect . 84. Dog's head, posterior aspect 35. Front view of the human cranium 36. External or basilar surface of human skull 37. The sternum . . . . < 38. Typical ribs of the Horse . 39. Thorax of Man, anterior face . 40. Eight scapula, outer surface head head PAGE Chauveau . 7 Chauveau . 7 Original 8 Original 9 Chauveau . 9 Carpenter . 13 Carpenter . 14 Carpenter . 14 Carperder . 17 After Owen . 19 Original . 22 Original 22 Original 23 Original 24 Chauveau . 26 Original 26 Original 27 Original 33 Chauveau . 38 Chauveau . 41 Original 46 Chauveau . 49 Chauveau . 50 Chauveau . 51 Chauveau . 53 Original 55 Chauveau . 56 Chauveau . 57 Chauveau . 58 Chauveau . 59 Chauveau . 60 Chauveau . 61 Chauveau . 62 Chauveau . 63 Wilson 64 Wilson 65 Chauveau . 66 Chauveau . 68 Wilson 71 Original 72 TABLE OF ILLV8TBATI0N8. FIGS. 41. Antero-external view of right humerus 42. Posterior view of right humerus . 43. External face of the radius and ulna . 44. Eight fore-foot of a Horse 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, front view 53. Fore-arm and foot of the Dog, anterior face 54. Human scapula, external aspect . 55. Eight human humerus, anterior surface 56. Human arm bones, front view . . 57. Palmar surface of left human hand 58. The Coxse, 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 metatarsus 69. Human pelvis, female 70. Eight human femur, anterior aspect 71. Human tibia and fibula of right leg, anterior aspect 72. Dorsal surface of left human foot . 73. Skeleton of a Fowl .... 74. Cephalic vertebrae of the Dog .... 75. Plans of the different classes of articulations . Beaunis 76. Section of branchial cartilage of Tadpole . 77. Fibro-cartilage .... 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 vertebrae, upper plane 84. Articulations of the ribs with the vertebrae, inferior plane 85. Scapulo-humeral and humero-radial articulations, external face 86. Carpal articulations, front view .... 87. Lateral view of the carpal articulations 88. Section of inferior row of carpal bones, and metacarpal and sus- pensory ligament ..... 89. Posterior view of metacarpo-phalangeal and interphalangeal articulations 90. Sacro-iliac and coxo-femoral articulations . 91. Femoro-tibial articulation . . . . . 92. Ligaments attaching the three bones of the leg PAGB 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 . 92 Original . 93 Original 94 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 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 Chauveau . ' 167 xxxviii TABLE OF ILLUSTBATIONS. FIGS. 93. Tarsal articulations, front view .... 94. Articulations of the tarsus, lateral view 95. Ultimate fibril of muscle ..... 96. Striated muscular tissue fibre .... 97. Termination of nerves in muscular fibre 98. Distribution of capillaries in muscle 99. Termination of nerves in an olemeniary muscular fibre 100. Striated fibre of muscle durin^^ contraction 101. Lateral view of the neck, superficial muscles . 102. Superficial muscles of the neck and spinal region of the back and loins ...... ] 03. Lateral view of the neck, middle layer of muscles 104. Cervical ligament and deep muscles of the neck . 105. Muscles of the spinal region of the neck, back, and loins 106. Deep ditto ...... 107. Muscles of the back and cervix of Man 108. Muscles of the sublumbar, patellar, and internal crural regions 109. Deep muscles of the sublumbar region 110. Superficial muscles of tlie face and head . 111. Hyoideal and pharyngeal regions .... 112. Superficial muscles of the Ox's head 113. Muscles of the human head 114. Muscles of the axillary and cervical regions 115. Axillary and thoracic muscles .... 116. Muscles of the inferior abdominal region . 117. Muscles of the anterior aspect of the body of Man 118. Diaphragm, posterior face .... 119. External muscles of the anterior limb 120. Muscles of anterior aspect of Man's upper arm 121. Internal aspect of left anterior limb .... 122. Deep muscles on external aspect of right anterior limb 123. Muscles of the fore-arm of the Ox . . . 124. Tendinous and ligamentous apparatus in the digital region of the Ox . 125. Muscles of the fore-arm and paw of the Dog . 126. Superficial muscles of human fore-arm 127. Deep layer of superficial muscles of human fore-arm . 128. Muscles of human hand ..... 129. Superficial muscles of the croup and thigh 130. Muscles of the sublumbar, patellar, and internal crural regions 131. Coccygeal and deep muscles surrounding the coxo-femoral articulation ...... 132. Superficial muscles of the croup and thigh in the Cow 133. Muscles of the anterior femoral region in Man 134. Muscles of the posterior femoral and gluteal region in Man 135. External deep muscles of right posterior limb 136. Flexor muscle of metatarsus ..... 137. Muscles on inner aspect of left posterior limb 138. External muscles of the leg of the Ox . 139. Muscles of the human leg, anterior tibial region . 140. Superficial posterior muscles of the human leg 141. First layer of plantar muscles of human foot 142. Third, and part of second layer of plantar muscles of human foot ...... PAGE Chauveau . 169 Chauveau . 171 Bowman . 178 Bowman . 178 Kiihne 179 Berres 180 Beale 180 Bowman . 181 Original . 188 Chauveau . 190 Original . 192 Chauveau . 194 Chauveau . 204 Chauveau . 207 WiUon . 210 Chauveau . 213 Chauveau . 214 Original 218 Original . 226 Chauveau . 228 Wilson 231 Chauveau . 232 Original 234 Chauveau . 243 Wilson 245 Chauveau . 247 Chauveau . 250 Wilson 255 Original . 257 Original . 260 Chauveau . 270 Chauveau . 271 Chauveau . 273 Wilson 275 Wilson 275 Wilson 279 Original 282 Chauveau . 290 Chauveau . 293 Chauveau . 294 Wilson 296 Wilson 296 Original 299 Chauveau . 300 Original 303 Chauveau . 307 Wilson 310 Wilson 310 Wilson 312 Wilson 312 TABLE OF ILLUSTRATIONS, FIGS. 143. Squamous epithelium from the mouth 144. Columnar epithelium ..... 145. Columnar ciliated epithelium .... 146. Conical villi on mucous membrane of small intestine . 147. Fusiform cells of smooth muscular fibre 148. Hard and soft palate ..... 149. Muscles of the tongue, soft palate, and pharynx 150. Lobe of racemose gland from the floor of the mouth 151. Follicular gland ...... 152. Median longitudinal section of the head and upper part of neck 153. Section through the fang of a molar tooth 154. Transverse section of enamel .... 155. Magnified section of a canine tooth 156. Theoretical section of dental sac of permanent incisor 157. Section of dentine and pulp of an incisor tooth 158. Dentition of inferior jaw of Horse .... 159. Incisor teeth of Horse, details of structure 160. Profile of upper teetii of the Horse 161. Transverse section of Horse's upper molar 162. The teeth of the Ox .... . 163. Ox's incisor tooth . . ... 164. Incisor teeth of a Sheep two years old • 165. Teeth of the Pig .... . 166. General and lateral view of the Dog's teeth 167. Anterior view of the incisors and canine teeth of Dog . 168. Section of the human face . .... 169. Lobule of parotid gland .... 170. Capillary network of follicles of parotid gland 171. Termination of the nerves in the salivary glands 172. Inferior aspect of head and neck .... 173. Maxillary and sublingual glands 174 Pharyngeal and laryngeal region .... 175. Median longitudinal section of head and upper part of neck 176. Muscles of the pharyngeal and hyoideal regions . 177. Human pharynx ..... 178. T] ansverse vertical section of head and neck 179. Pectoral cavity and mediastinum 180. Theoretical transverse section of abdominal cavity 181. Theoretical, longitudinal, and median section of abdominal cavity ...... 182. The abdominal cavity, with the stomach and other organs 183. Stomach of the Horse ..... 184. Interior of the Horse's stomach 185. Muscular fibres of stomach, external and middle layers 186. Deep and middle muscular fibres of stomach 187. Peptic gastric gland ..... 188. Portion of a peptic csecum 189. Mucous gastric gland ..... 190. Capillaries of mucous membrane of stomach 191. Stomach of the Dog ..... 192. Stomach of the Ox 193. Interior of the stomach of Kuminants . 194. Section of the wall of the omasum of Sheep 195. Section of a leaf of the omasum XXXIX WUson PAGE 327 , Kolliker . 327 Carpenter . 327 . Wilson 328 Bowman . 328 . Chauveau . 333 Chauveau . 338 . Kolliker . 339 KoUiher . 339 Original . 341 . Carpenter . 345 Carpenter . 346 . Wilson 347 Chauveau . 348 . Carpenter . 349 Chauveau . 350 . Chauveau . 351 Chauveau . 353 . Chauveau . 354 Chauveau . 357 . Chauveau . 358 Chauveau . 359 Chauveau . 360 Chauveau . 361 Chauveau . 361 Quain 362 . Wagner 365 Berres 365 . Bfliiger 366 Original . 367 . Chauveau . 368 Original . 372 Original . 373 Original . 375 . Wilson 377 Original . 378 Chauveau . 379 Chauveau . ,1 382 Chauveau . 383 Original . 386 . Chauveau . 387 Chauveau . 388 Chauveau . 390 Chauveau . 390 . Kolliker . 391 Kolliker . 391 . Kolliker . 392 Carpenter . 392 Chauveau . 393 Chauveau . 394 Chauveau . 395 Chauveau . 398 After Chauveau 399 xl TABLE OF ILLUSTBATIONS, FIGS. 196. Longitudinal section of a large pupilla from the omasum 197. Villi of human and Sheep's intestine . 1 98. Portion of Brunner's gland 199. Section of mucous membrane of small intestine 200. Section of mucous membrane of large intestine 201. Injected villi of intestine .... 202. Blood-vessels in Peyerian glandulse 203. Diagram of origin of lacteals in villi . 204. General view of the intestines of the Horse, right side 205. General view of the Horse's intestines, inferior aspect . 206. The colon of the Horse .... 207. Pkn of the colon ..... 208. General view of the intestines of the Ox . 209. Intestines of the Dog ..... 210. Human intestines ..... 211. Abdominal cavity, with the liver and other organs 212. Portion of a hepatic column, with secreting cells . 213. Biliary capillaries and ducts .... 214. Blood-vessels in lobules of liver . . . 215. Section of lobules of liver, with intralobular veins 216. Excretory apparatus of the Horse's liver . 217. Malpighian corpuscles attached to splenic artery 218. Splenic corpuscle from the spleen of Ox . 219. Liver of the Dog, with its excretory apparatus 220. Under surface of the human liver . 221. General view of the digestive apparatus of a fowl 222. Cartilages of the nose .... 223. Transverse section of the head of Horse 224. Longitudinal section of the head, and upper part of neck 225. Cells of the olfactory mucous membrane 226. Fibres of olfactory nerve .... 227. Superior face of larynx .... 228. Inferior face of larynx .... 229. Postero-lateral view of larynx .... 230. The respiratory organs, inferior aspect 231. Ciliated epithelium from the trachea . 232. Bronchial tube, with its bronchules 233. Mucous membrane of a bronchial tube 234. Tlie pectoral cavity and mediastinum 235. Theoretical section of thoracic cavity, behind the heart 236. Theoretical section of thoracic cavity, at root of lungs 237. Theoretical section of thoracic cavity, in front of right ventricle 238. Plan of a pulmonary lobule .... 239. Air-cells of lung ..... 240. Capillaries and air-cells of lung 241. Lung of the Sheep, inferior view . 242. Human lungs and heart .... 243. Gland vesicles of thyroid 244. Portion of thymus of calf .... 245. Course and termination of ducts in thymus gland of calf 246. General view of the air-sacs in tlie duck . . 247. General view of the geni to-urinary apparatus in the male 248. Horizontal longitudinal section of the Horse's kidney . 249. Section of the cortical substance of the kidney Chauveau . 399 Teichmann . 403 Thmnson . 403 . Teichmann . 404 Teichmann . 405 . KolUker . 405 KolUker . 406 . Funhe 406 After Chauveau 408 . Chauveau . 409 Origirial . 410 Chauveau . 411 Chauveau . 415 Chauveau . 416 Wilson 417 . Original . 421 Leidy 423 Irminger and Frey 423 Kiernan . 424 . Kiernan . 424 Chauveau . 425 . KolUker . 430 KolUker . 430 . Chauveau . ■ 433 Wilson 434 Chauveau . 436 Chauveau . 440 Chauveau . 442 Original . 443 Clarke and Schultze 445 Ecker 446 After Chauveau 452 After Chauveau 452 . Original . 454 Original . 458 . KolUker . 459 Heale 460 . Heale 461 Chauveau . 463 . Chauveau . 465 Chauveau . 465 itricle Chauveau . 465 . Waters 468 KolUker . 469 Carpenter . 469 Chauveau . 471 Wilson 471 KolUker . 472 . KolUker . 474 Wilson 474 Chauveau . 480 Chauveau . 485 Chauveau . 487 Ecker 488 TABLE OF ILLUSTRATIONS. PIGS. 250. Course of the uriniferous tubuli 251. Diagram of the circulation in the kidney . 252. Transverse horizontal section of kidney 253. The kidneys and bladder in the foetus of Solipeds 254. Right kidney of Ox, upper and external face . 255. Left kidney of Ox, internal and inferior face 256. The calicos in left kidney of Ox 257. Theoretical plan of the circulatory system . 258. The heart and principal vessels, left face 259. The heart and principal vessels, right face 260. Right side of the heart laid open 261. Section of the heart at the level of the valves 262. Left cavities of the heart laid open 263. Anastomosing muscular fibres of heart 264. Epithelium of the endocardium 265. Human lungs and heart, front view 266. Web of Frog's foot, showing blood-vessels and their anastomoses 267. Epithelial cells of blood-vessels .... 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 genito-urinary 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 ..... 286. Arteries of the head ..... 287. Re'seau admirable of the Sheep, seen in profile . 288. Reseau admirable of the Ox, posterior face 289. Arteries of the face and head of Man .... 290. Roots of the superior jugular vein, with its collateral affiuents 291. Section of the ci anial cavity and spinal canal 292. Veins of the foot . . 293. General view of the veins in the Horse 294. The vena portss 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 lympnatic gland of Ox . 299. Ordinary disposition of the thoracic duct . 300. Double variety of the thoracic duct . . ... 301. Triple variety of the thoracic duct 302. Lymphatic system of the Horse .... xli PAGE Hertz 488 Bowman . 489 Original . 489 Chauveau . 492 Chauveau . 496 Chauveau . 498 Chauveau . 496 Colin 498 Chauveau . 501 Chauveau . 502 Wilson 504 Sihson 505 Wilson 507 Kolliker . 509 Kolliker . 511 Wilson 514 Wagner 518 Kolliker . 518 Kolliker . 519 Kolliker 519 Kolliker . 519 Chauveau . 530 Chauveau . 533 Chauveau . 536 Chauveau . 539 Chauveau . 542 WUson 544 Chauveau . 546 Chauveau . 552 Wilson 558 Wilson 558 Wilson 559 Chauveau . 562 Chauveau . 568 Wilson 574 Chauveau . 580 Chauveau . 583 Chauveau . 593 Chauveau . 594 Heath 595 Chauveau 604 Chauveau . 607 After Bouley 614 Chauveau . 618 Chauveau . 620 Teichmann. 631 Kolliker . 632 Teichmann . 632 Kolliker 633 Colin 636 Colin 636 Colin 636 Colin 639 xlii FIG:^. 303. 304. 305. 306. 307. 308. 309. 310. 311. 312. 313. 314. 315. 316. 317. 318. 319. 320. 321. 322. 323. 324. 325. 326. 327. 328. 829. 330. 331. 332. 333. 334. 335. 336. 337. 338. 339. 340. 341. 342. 343. 344. 345. 346. 347. 348. 349. 350. 351. 352. 353. 3.54. TABLE OF ILLVSTEATIONS. Great lymphatic vein and entrance of the thoracic duct . Colin Great lymphatic duct, another variety . . . Colin Thoracic duct in the Ox . . . . . Colin A variety of the thoracic duct in the Ox . . . Colin Anotlier variety of the thoracic duct . . . Colin A fourth variety of the thoracic duct .... Colin Thoracic duct of small Kuminants. . . . Colin Diagram of structure of nerve-fibre . . . . Carpenter . Multipolar, or stellate nerve-cell .... JEcker Ganglion from lieart of Frog ..... Eclcer Bipolar ganglionic cells and nerve-fibres . . . Ecker Stellate nerve-cell ..... . Beale Structure of ganglionic cells .... Beale and Arnold General view of the spinal cord .... Colin Segment of the spinal cord at the cervical bulb . . Colin Section of the spinal cord of the Horse at the lumbar region . Chauveau . Transverse section of spinal cord of Man at the middle of the lumbar region . . . . . . I. L. Clarke 670 Longitudinal section through cervical bulb of spinal cord of the Cat . . . . . . . I.L. Clarke General view of the brain, upper surface . . . Chauveau . General view of the brain, lower surface . . . Original . Superior view of the encephalic isthmus . . . Chauveau . Lateral view of the isthmus .... Chauveau . Transverse section of the encephalon .... Chauveau . Dissection of the medulla oblongata . . Solly and Carpenter Median and vertical section of the encephalon . . . Chauveau . Section of the cortical substance of the cerebellum . . Kolliker Antero-posterior and vertical section of the encephalon . Chauveau . Corpus callosum . . . . ^ . Chauveau . Anterior portion of the lateral ventricles . . . Chauveau . Corticle substance of the cerebral hemispheres . . Kolliker PAGE 645 645 645 646 646 646 647 652 653 654 654 654 654 667 667 669 Base of the human brain Muscular fibres, with termination of motor nerve Nerves of the eye ..... General view of the superior and inferior maxillary nerves Section through the summit of the medulla oblongata . Origin of the nerves arising from the medulla oblongata . Pneumogastric nerve, with its branches in the neck Origin and distribution of the eighth pair of nerves in Man Distribution of the nerves in the larynx of the Horse . Deep nerves of the head . Nerves of the guttural region in the Ox Nerves of the face and scalp of Man Distribution of eighth pair of nerves on left side Ganglion of a spinal nerve from the spinal region Nerves of the brachial plexus . External nerves of anterior limb . Nerves of the digit of Horse . Nerves of the digital region of Euminants . Nerves of the palmar face of Dog's foot Nerves of the palmar face of Cat's foot Nerves of the axilla of Man Nerves of the front of fore-arm and hand of Man Hirschfeld and Leveille' Cohnheim . Chauveau . Chauveau . Carpenter . Toussaint . Toussaint . Wilson Toussaint . Chauveau . Toussaint . Hirschfeld and Leveille' Hirschfeld and Leveille" Kolliker . Chauveau . Chauveau . . Bouley Chauveau . Chauveau . Chauveau . Hirschfeld and Leveille" Hirschfeld and Leveille' 671 673 676 678 680 682 684 687 689 690 693 696 697 699 702 708 714 721 730 731 732 734 738 740 745 746 748 757 759 762 764 766 767 768 769 TABLE OF ILLUSTRATIONS, FIGS. 355. Lumbo-sacral plexus and internal nerves of posterior limb 356. Posteiior portion of the lumbo-sacral plexus 857. External nerves of posterior limb 358. Lumbar plexus of Man 359. Nerves at the posterior aspect of human leg . 360. Nerves at the front aspect of human leg . 361. Sympathetic ganglion from a Puppy . 362. Sympathetic system of the Horse , 363. Section of Horse's skin 364. Capillary loops in cutaneous papillae 365. Tactile papillae from the skin . 366. Interungulate gland of Sheep 367. Branches of cutaneous nerves in skin . 368. Sudoriparous giand 369. Oblique section of epidermis . 370. Longitudinal median section of Horse's foot 371. Horizontal section of Horse's foot 372. Lower surface of the Horse's foot . 373. Lateral view of the Horse's foot 374. Hoof removed from the foot 375. Hoof with outer portion of wall removed 376. Plantar surface of hoof 377. Horn-cells from the sole of hoof .... 378. Constituent elements of the wall .... 379. Horizontal section of the junction of the wall with the sole of hoof ...... 380. Horizontal section of wall, and horny and vascular laminae 381. Fibres of ultimate ramifications of olfactory nerves 382. Cells of olfactory mucous membrane 383. Theoretical section of the Horse's eye .... 384. Anterior segment of a transverse section of the globe of the eye (human) . . , , . 385. Cells from pigmentum nigrum 386. The eye (human) witli the sclerotic coat removed . 387. Muscular structure of the iris .... 388. Vertical section of retina . . , . 389. Diagram of the structure of the retina 390. Capillaries in the vascular layer of the retina 391. Muscles of the eye-ball, viewed from above 392. Section of lamina spiralis of the cochlea . 393. /Section of the cochlea parallel to its axis 394. Right tympanic cavity of Horse's ear 395. Bones of the middle ear of the Horse . 396. Muscles of the ear . . 397. Human testis, ii^ected with mercury . 398. Vertical section of the Horse's testis 399. Internal genito-urinary organs of the foetus of a Mare. 400. Spermatozoa of various animals 401. Diagram of the testicle .... 402. Superior view of the genito-urinary organs 403. Longitudinal section of the free extremity of the Horse's penis 404. Sections of the urethra of the Ox at different points 405. Penis and muscles of the sheath of the Bull . 406. Section of human pelvis .... Chauveau . Chauveau . Chauveau . HirscJi/eld and Leveill^ Hirschfeld and Leveille' Mirschfeld and Leveille . Kolliker Chauveau . Chauveau . Berres . Ecker Owen Ecker Wagner Carpenter , Original . . Original . Original . Original . Leisering . Leisering . Leisering . Leiserifig Leisering . Leisering . Ecker Clarke and Shultze Chauveau . Wilson Carpenter Holden Kolliker Muller Krause Berres Original Carpenter Breschet Chauveau Lavocat Original Lauth Chauveau Chauveau Carpenter Holden Chauveau Chauveau Chauveau Chauveau Gray xliii PAGE 771 773 776 779 780 780 782 784 793 793 794 794 795 795 796 800 801 802 8-3 806 806 807 801) 810 811 811 816 816 818 821 822 823 823 825 826 826 829 888 838 841 843 848 854 855 857 858 859 86d 866 868 869 871 xliv TABLE OF JLLUSTBATI0N8. FIGS. 407. Ovarium of the Eabbit .... 408. Constituent parts of mammalian ovum, entire 409. Constituent parts of mammalian ovum, ruptured 410. Formation of the corpus luteum .... 411. Generative organs of the Mare, isolated 412. Generative organs of the Mare, in situ 413. Termination of milk-duct in cluster of follicles 414. Ultimate follicles of mammary gland, with secreting cells . 415. Microscopic appearance of milk 416. Human uterus, with its appendages 417. First stages in segmentation of mammalian ovum 418. Later stages in segmentation .... 419. Section through embryo of the Chick, first day of incubation 420. Plan of early uterine ovum .... 421. Diagram of ovum at formation of the amnion . 422. Exterior of the chorial sac, Mare .... 42-3. Fecundated egg, showing formation of amnion and allantois 424. Fecundated egg, with amnion nearly completed . 425. Foetus of the Mare, with its envelopes. 426. Portion of ultimate ramifications of umbilical vessels 427. Portion of one of the foetal villi 428. Equine foetus, opened on left side to show umbilical vessels 429. Blood-vessels in liver of an equine foetus at mid-term , 430. Liver of a Lamb at birth ..... 431. Diagram of an early human ovum 432. Diagram of a human ovum in second month 433. Early stages in the development of a Fowl 434. Transverse section of embryo of Chick on third day 435. Plan of development of eye .... 436. Origin of encephalic centres in human embryo of sixth week 437. Plan of chorda dorsalis at period of formation of embryo . 438. Plan of vertebra at an early period of development 439. Head of a foetal Lamb, showing Meckel's cartilage 440. Plan of first system of vessels, embryo . 441. Embryonic heart at an early period, anterior view 442. Ditto, seen from behind .... 443. Heart of an equine foetus ..... 444. Plan of the aorta and its arches at an early period 445. Plan of the circulation in the human embryo, side view 446. First appearance of the lungs .... 447. Embryo of Dog at twenty-five days 448. Origin of liver from intestinal wall of embryo Chick . 449. Urinary and genital apparatus in embryo Chick . 450. Sediion of Fowl's egg ..... PAGE . Pouchet 874 Coste 875 . Coste 875 Pouchet 875 Chauveau . 878 Ghauveau . 881 , Sir A. Cooper 885 Lebert 885 . Funhe 885 Wilson 888 . Coste 891 Coste 891 . Kmiiker . 893 Wagner 894 Wagner 894 Chauveau . 895 . Dalton 896 Dalton 896 Chauveau . 898 Carpenter . 899 . Echer 900 Chauveau . 901 . Colin 902 Colin 902 Wagner 904 Wagner 904 . Huxley 906 Kolliker . 908 . Kolliker . 909 Wagner 910 Kolliker . 912 . Kolliker . 912 Huxley 913 . Kolliker . 914 Kolliker . 915 . Kolliker . 915 Chauveau . 916 . Kolliker . 917 Coste 918 Wagner 919 Bischof . 919 . Muller 922 Muller 922 Allen Thomson 925 THE COMPAEATIVE ANATOMY OF THE DOMESTICATED ANIMALS. GENEEAL CONSIDEEATIONS. 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 pathological 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. Descriptive 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, Eestricted 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. GENERAL CONSIDEBATIONS. ENU3IERATI0N AND CLASSIFICATION OF THE SPECIES OP 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 Bahhit ; 8. A pachyderm, the Fig ; 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 fowly 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 hisulcate 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 Iolyo 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, etc., 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 difier- 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. GENERAL CONSIDERATIONS, 3 GENERAL IDEA OF THE ORGANISATION OF ANIMALS. Order followed in studying the Various Apparatus. The bodies of animals, formed of organised matter, contain fluids and solids. The fluids are very abundant in the animal economy ; not only do they fill certain vessels constructed for them, but they also impregnate all fclie 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. Elements. — 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. It has therefore received various names. There are round, polyhedral, fusiform, stellate, and other shaped cells. Some have a diameter of 1-1 2000th part of an inch, while others are l-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 (endogenous multiplication^; 2nd, by constriction, the division of the nucleus, protoplasm, and enveloping membrane (fssiparous 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 fibrillae 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 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. Hcematies or red globules, which are found in a state of suspension in the blood ; they are round or elliptical. 2. Leucocytes, or white globules, which float in the blood, lymph, and chyle. 3. Connective cells, comprising the connective cell properly so-called, the plasmatic cell, and the adipose cell. 4. Medullary cells, forming the principal elements of the marrow of bones (myeloplaxes and meduUo-cells). 5. Contractile cells, which constitute the basis of muscular tissue. 6. Nerve cells, met with in the cerebro-spinal centres and the ganglia of the cerebro-spinal and sympathetic systems. 7. 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 envelope. 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 fibre, elastic fibre, muscular fibre, and nervous (or nerve) fibre. Tissues.-— 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 Q^i\hQ]iviTii\^ polyhedral, ^pavement, cylindrical, or spherical. In certain points, these superficial cells are furnished with vibratile filaments ; they are then designated vibratile (or ciliated) epithelium. GENEBAL C0NS1DEBATI0N8, 5 In the third place, is the muscular tissue, which may be divided into striated and non-striated (or striped, and non-strijped 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 by fibres and nerve cells. Organs. — The term organ is given to an agglomeration of tissues possessing a determinate form, and having a function to fulfil. Organs are therefore composed of tissues, as the tissues themselves are constituted by anatomical elements. All animal organs are enclosed between two membranes named limitary or tegumeniary 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 vascular 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 the 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 them. 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 : — 1. Locomotor^ Apparatus ; 2. Digestive Apparatus ; 3. Respiratory Apparatus ; 4. Urinary Bepurative Apparatus ; 5. Circulatory Apparatus; 6. Innervatory Apparatus ; 7. Sensory Apparatus ; 8. Generative Apparatus ; This description will be terminated by a brief exposition of the evolution of the foetus and its appendages, 4 BOOK I. LoooMOTOKY Apparatus. The 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 hones and muscles. The hones, 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. FIEST SECTION. The Bones. CHAPTEE I. 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 sJceleton ; 2, The summary indication of the general p-inciples which should be known in order to com- prehend the details of the special descriptions. TRE SKELETON. 7 Article I. — The 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 SKELETON OF THE DOG. Fig. 2. SKELETON OF THE PIG. 8 TEE 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 replace them by materials foreign to organisation, such as iron or brass wire. The skeleton is divided into trunk and limhs. The trunk offers for consideration, in the median line, the sjpine 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 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 thorax, a spacious cavity destined for the reception of the principal organs of re- spiration and circulation. The limbsy 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 haunch or pelvis, which articulates with the posterior part of the spine ; and the thigh, leg^ and posterior foot. ll'ME SKELETON. 9 In birds, the posterior limbs alone assume the function of columns of support. The anterior limbs, formed for flight, constitute the wings. Fig. 4. SKELETON OF THE COW, Fig. 5. SKELETOir OP THE SHEEP. The nuniber of bones entering into the composition of the skeleton of the domesticated animals, arrived at the adult period of life varies according 10 GENERAL PBINGIPLE8 APPLICABLE TO to tlie species. They are apportioned to the regions of the trunk and limbs just mentioned, in the manner indicated in the following table : DESIGNATION. Vertebral Column ^ Head* , . . . Thorax. . . . Shoulder - ^ Arm . Fore-arm Fore-foot Pelvis Thigh Leg . Hind-foot . Double regions Solipeds.i 44 28 37 1-2 1-2 2-4 16-32 1-2 1-2 3-6 15-30 Ruminants. 43 28 27 1-2 1-2 2-4 20-40 1-2 ]-2 3-6 19-38 Pig. 42 29 29 1-2 1-2 2-4 36-72 1-2 1-2 3-6 36-72 43 28 27 1-2 1-2 2-4 36-72 1-2 1-2 3-6 32-64 Article II. — General Principles Applicable to the Study of all THE Bones. The description of any bone comprises its namej 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 (cotes, 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 rul^s, but the new designations proposed have not been sanctioned by custom. Situation, The situation of a bone should be viewed in two ways : 1st, Belative to the median plane of the body ; 2nd, Belative 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. * The OS penis has not been included. ^ The sacrum is reckoned as a single bone, and the number of coccygeal vertebrae 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. TEE STUDY OF THE BONES. 11 B. Belative situation to the other jparts of the skeleton. — To indicate the situation of a bone, considered from this point of view, is to make known the place it occupies 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 hone. 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 hones, h. A bone that offers two dimensions much more developed than the third, is a flat or wide hone. 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, c. A bone which offers nearly the same development in all its dimensions, is called a short-hone. 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. Belative 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. External Peculiarities of 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 synarthrodial 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 insertion. (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 aponeuroses.) The synarthrodial eminences are always indentations more or less deep and ^nely cut. 12 GENERAL PBINCIPLES APPLICABLE TO The diarihrodial 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 humerus) ; condyles, when they represent the segment of an oval figure, cut parallel to its large axis (condyles of the femur.) 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 and 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 bony 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 ; fissures, 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 fossce, 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 margins. 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. Eegions op the Bones. — 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 plane or salient angles, which are often neglected because of their trifling importance. 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 category 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 very dense bony tissue, whose pores are scarcely visible to the naked eye, and which is called the comjjact 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 areolsB, which freely communicate with each other. (Beticulated 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 lamellce,) The medullary canal, and areola3 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 laminaB 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 diploe. 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 bones, to which it affords increased size without adding sensibly to their weight. Structure of Bones, Bones are formed of a proper tissue, covered membrane, the periosteum, and occupied internally by the medulla, vessels, and 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 l-2500th to l-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- "Towt^, Th^ J^rS neath the periosteum, and the deepest into the Haversian canals. externally by a particular Fig. 6. 14 GENERAL FBJNCIPLE8 APFLICABLE TO medullary canal; while a certain number terminate in the areolaB of the spongy substance. The walls of these canals are constituted by several concentric lamellae of fundamental substance, and in the body of these are lodged the essential elements of the bony tissue, or osteoplasts (corpuscles or lacunce). These are minute cavi- ties lined by a cellular membrane, and furnished, at their circum- 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 appear black by transmitted light, and white and brilliant by direct light ; OF BONE as shown in a thin- ^j^jg appearance has led some ob- jrsely to the direction of the ^\ .1. j. .1 servers to suppose that they were formed of small masses of calca- reous matter. It is now well known that they are minute ramifying cavities, lodging a cell MINUTE STRUCTURE section cut transversely Haversian canals. 1, A Haversian canal surrounded by its concentric lamellae; the. lacunae are seen between the la- mellae, but the radiating tubuli are omitted; 2, Ibidf with its concentric laminae, lacunae, and radiating tubuli; 3, The area of one of the . '1. j 'jt. t -j canals; 4, 4, Intervening lamella, and between ^"'P^^g''^*.^ '^^^il'l'''^ them, at the upper part, several very long - a - - lacunae with their tubuli. Fig. 8. In the spongy texture no Haversian canals can be seen^ the osteoplasts are irregularly disposed in the thickness of the fundamental substance, which con- stitutes the septa of the areolae 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. Periosteum, — 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. LACUNA, OR OSTEOPLASTS OF OSSEOUS SUBSTANCE, magnified 500 diameters. a, Central cavity ; 6, Its ramifications. TEE 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 osteogenous layer. Medulla, — The medulla, or marrow, is a pulpy, fatty substance, which fills the medullary canal and the areolse 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. In 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 trabeculse 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. Eobin meduUo-celh and myeloplaxes. The medulla cells, abundant in the red or foetal marrow, are small cells with a spherical nucleus; while the myeloplaxes are large, flattened, or polyhedral elements of an irregular outline, containing a great number of nuclei. Eare in the yellow marrow, they are more particularly found adhering to the walls of the medullary canal, or the alveoli of the spongy tissue. Blood-vessels, — 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 comniunicates 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 vertebrae, are especially remarkable for the numerous nerves they receive. 16 GENERAL PBINCIPLES APPLICABLE TO DEVELOPMENT OP 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 composed 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. At a 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. These 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 one 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. Oilier and Humphry, have remarked that, in the thoracic limb, the extremity furthest removed from THE STUDY OF THE BONES. 17 Fig. 9. the liumero-radial articulation grows fastest ; while in the abdominal limb, the extremity most distant from the femoro-tibial articulation grows the least. Concerning 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 experiments of the above-named authors have irrefutably demonstrated this fact. 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 layers 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 laminae ; they increase in width by the ossification of what are termed the marginal epiphyses. The short bones grow from the periosteum and the epiphysery cartilages, 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 numerous 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 in rows, with intercellular tracts, where the ossification is about to begin, as in fig. 9. These rows, in the cartilaginous basis of long bones, are vertical to its ends ; in that of flat bones they are vertical to the margin. The cells furthest from the seat of ossification are flattened and in close contact ; nearest that seat 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 bone by CARTILAGE AT THE SEAT OP OSSIFICATION, showing at its lower portions the clusters of cells arranged in columns, each of which is inclosed in a sheath of calcified intercellular substance. 18 THE BONES absorption, which ultimately receive bloodvessels, and become the ' vagcnlar 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 ' lacunse ' or * bone-cells,' and to some extent characterise, by their shape and size, the osseous tissue of the respective vertebrate classes. In the concentric laminae surrounding the vascular canal, the bone-cells or osteoplasts are arranged concentrically, between the laminae, 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 over 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 fiirst solid.") CHAPTER II. THE BONES OF MAMMALIA IN PARTICULAB. Article I. — ^Vertebral Column. The 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 vertebrae. These THE VEBTEBBAL COLUMN, 19 bones, though all constructed on an uniform type, yet do not o£fer the same configuration throughout the whole rachidean stalk. The differences they present into this respect, have allowed of their being formed into five prin- cipal groups ; whence the division of the vertebral column in five regions, which are, enumerating them from before to behind : 1, Cervical region ; 2, Dorsal region ; 3, Lumbar region ; 4, Sacral region ; 5, Coccygeal region. The first comprises seven vertebrae, which serve as a base 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 are 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 vertebraB, gradually decreasing in size to form the tail. The pieces consti- tuting the first three regions are called true vertebras ; those of the last two are designated false vertebrae. The characters belonging to all these verteorae will be first studied; then a particular description of the vertebraB of each region will be given ; and, finally, an examination will be made of the spine as a whole. CHARACTERS COMMON TO ALL THE VERTEBR-ffll. Each of these small bones is pierced from before to behind by a wide Fig. 10. i^i ELEMENTS OF A VERTEBRA; AFTER OWEN. A, Ideal typical vertebra ; b. Actual thoracic vertebra of a bird ; c, Centrum (or hody\ giving off, cf, d, the diapophyses, and jo, p, the parapophyses (transverse and articular processes) \ the neural arch, inclosing the spinal cord, is formed by w, w, the neurapophyses (lamince), and n, s, the neural spine (spinous process) \ the haemal arch, inclosing the great centres of the circulation, is formed by A, hy the hsemapophyses (costal cartilages)^ and A, s, the haemal spine (sternum). From both the neurapophyses and hsemapophyses maybe given off the zygapophyses, Zy z. The lateral arches, which may inclose the vertebral arteries, o, o, are completed by the pleurapophyses (ribs), pi. ; these in b are bent downwards, so as to form part of the haemal 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 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 foetus, two distinct pieces, which do not become united for a long time after birth. Body. — 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. Annular 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. 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 pos- terior articular processes are inclined downwards, to correspond with the anterior facets of the succeeding vertebra. Structure of the vertebrce. — 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 proceeds from a single centre of ossification. The union of the two centres in the annular portion, usually designated the vertebral lamince, is slower. It commences in the most anterior vertebrae, and is latest in the sacral and coccygeal 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 summit of each transverse process, another for the head, and the last for the posterior cavity of the body. CHARACTERS PROPER TO THE VERTEBRA OP 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 process, and the foramen which traverses the base of its transverse processes. The 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 coccygeal vertebra offers rudimentary laminae 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 Vertehrce, General Characters. — These vertebrae, the longest and thickest in the spine, present generally a cubic form. They are usually distinguished from the vertebras 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 5eep, 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 prominent, are inclined downwards and inwards. The notches are wide and deep. Specific Characters. — The seven cervical vertebrae are reckoned from before to behind, and receive numerical names indicating their place in the region. First. — The first vertebra of the neck, which has been named the atlas,^ deserves a very careful description. At first sight there is recognised the * So named from the mythological personage who was supposed to support the earth, as the first vertebra (human) supports the head. (For this bone in the domesticated animals the name is not appropriate.) 5 22 THE BONES. Fig. 11. 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 deep excavations, which lodge the venous sinuses ; the other, posterior, is smooth 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 atlas; inferior surface. provided with a thick rugged lip. Pos- a, Articular processes for condyles of teriorly, quite at their base, and on each side the occipital bone ; 2, ibidem ; 3, of the spinal foramen, they show two large Vertebral or antero-internal fora- vertical facets which represent the posterior men; 4 Posterior, or cervical fora- articular processes ; these facets are uneven, men: 5, Iransverse process; 6, /» t t -ii j_i j.- i -j. ^ Tubercle representing the inferioi- ^re confounded With the articular cavity of spinous process ; 7, Superior arch, the Upper face of the body, and correspond forming the roof of the spinal fora- 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 veTtebral foramen of the other ver- tebrae ; 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 laminae of the atlas, and opens, on one side, into the spinal tubercles or "rudimentary ribsj 8, canal, and on the other, beneath the trans- Inferior crest, or spine; 9, Concave ^^^g^ process. The atlas contains much posterior face. \ ,. , . n j i j compact tissue, and is generally developed from six centres of ossification : 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 axis (or dentata). It is the longest of all the cervical vertebrae ; those which succeed it gradually diminish in length and augment in thickness. The body of the axis has not any head anteriorly, Fig. 12. :i7 , An- A CERVICAL VERTEBRA. }1, Superior spinous process; 2. terior articular processes ; 3, Pos- terior articular processes ; 5, An- ^tfirior convex face of bodyj 6, 7, Transverse processes, with their THE VERTEBRAL COLUMN. 23 but a 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- cular 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- 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 roughened lips.^ The transverse pro- i^ Superior 'spinous process; 2, Odontoid pro. cess; 3, Intervertebral foramen, or hole of conjugation ; 4, Body ; 5, Inferior spinous process ; 6, 7, Inferior and superior articu- lating processes. This vertebra, although voluminous, THE AXIS, OR DENTATA; LATERAL VIEW. cesses are slightly developed, and ter- minate posteriorly in a single tubercle, directed backwards. The anterior notches are very deep, and are most frequently converted into foramina. 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 vertebrae 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 gradually 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 vertebrae, 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 trans.verse processes, which are uni tuberculous ; 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 Vertehrce, General Characters. — In the dorsal vertebrae the body is very short, and in front has a large slightly projecting head ; behind, it has a shallow cavity. Laterally, these vertebrae 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 corresponding 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. Specific Characters. — None of the eighteen dorsal vertebrae differ much from the type just described ; and it is difficult to establish special characters for each. It is, nevertheless, possible to assign to a 1, Body; 2, 27Articular facets for the ANIMALS. 1. Sternum, In all the domesticated animals except solipeds, the sternum is flattened above and below, instead of from side to side. KuMTNANTS. — In luminants, each piece is developed from two lateral centres of ossifica- tion. The bones which compose it are seven in number ,• they are much more compact than those in the sternum of the horse, and at an early period are united to each other, with the exception of the first, which is joined to the second by a diarthrddial articula- tion that permits it to execute lateral movements. There is no cervical prolongation, and the xiphoid cartilage is feebly developed and well detached from the body of the bone. In the sternum of tiie Goat and Sheepy the two first pieces have no diarthrodial joint, but are simply united by a layer of cartilage which, in old animals, becomes completely ossified. Pig. — The sternum of this animal presents in its general conformation the essential features of that of large ruminants. It is provided with a well-defined cervical prolonga- tion, and is composed of six pieces which, at least in the four or five last, are each divided into two lateral centres. Carnivora. — The sternum of the Bog and Cat is formed of eight pieces elongated from before to behind, hollowed in their middle part, and thick at their ends — formed, indeed, like the last coccygeal vertebrae of the Horse. They are never ossified to each other. TEE TEOBAX, 71 2. Ribs. The number of ribs varies like that of the dorsal vertebrae. The following table indicates the number of these bones in the difierent domesticated animals. Pig U Ox 13 Sheep, o 13 Goat 13 Dog 13 KuMiNANTS. — These animals have eight sternal and five asternal ribs. In the Oxy they are longer, wider, and less arched than in solipeds. The articular eminences of the superior extremity are voluminous and well detached; the neck especially is very long. The sternal ribs are joined to their cartilage of prolongment by a real diarthrodial articulation. In the last rib, and sometimes in the one before it, the tuberosity is scarcely perceptible, and has no articular facet. In the Sheep and Goat, the sternal ribs are consolidated with the cartilages (see fig. 5.) Pig. — In this animal there are fourteen pairs of ribs, seven of which are sternal and seven asternal. The first are provided with cartilages of prolongment flattened on both sides, extremely wide and sharp, and convex on their superior border. In the four last asternal ribs, the facet of their tuberosity is confounded with the posterior facet of the head. (Otherwise, the ribs of the Pig resemble, in their general conformation, those of the Sheep or Goat ; though more incurvated and wider.) Carnivora. — They possess thirteen ribs Fig. 39. on each side — nine sternal and four asternal. , These are very much arched, narrow, and ''\*^ thick, and their cartilages farely ossify. In the Dogf, the articular facet of the tuberosity remains isolated from the posterior facet of the head in all the ribs. It is absent in the three last ribs of the Cat. COMPARISON OF THE THORAX OP MAN WITH THAT OF THE DOMESTICATED ANIMALS. 1. Sternum, The sternum of Man is flattened before and behind, and diminishes in width from above to below. The xiphoid appendage is narrow, and single or bifid. Besides the articular surfaces for the ribs, there are found on the upper end two lateral notches for articulation with the clavicles. 2. Bibs. Of the twelve ribs in Man, seven are sternals and five astemals. They are short, narrow, and much incurvated, especially the first ones. In each rib the curvature is more marked in the posterior fourth or fifth than in the anterior three-fourths or four- fifths; this sudden change of curvature is indicated in the external face by a kind of inflexion and thickenino^ called the angle of the ribs. The prolonging cartilages of the . eleventh and twelfth ribs are short, and are lost in the texture of the abdominal parietes ; for this reason they are termed the floating (or false) ribs (see fig. 39). THORAX OF man; ANTERIOR FACE. 1, Superior piece of the sternum; 2, Middle piece, or body ; 3, Inferior piece, or ensiform cartilage; 4, First dorsal vertebra ; 5, Last dorsal vertebra ; 6, First rib ; 7, Its head ; 8, Its neck, rest- ing against the transverse process of the first dorsal vertebra; 9, Its tubercle ; 10, Seventh, or last true rib; 11, Costal car- tilages of the true ribs; 12, The last two false or floating ribs; 13, The groove along the lower border of the rib. Article IV. — Anterior Limbs. The anterior (or thoracic) limb is divided into four secondary regions : the shoulder, arm, fore-arm, and fore-foot or hand. 72 THE BONES, Fig. 40. SHOULDER. In solipeds, this region has for its base a single bone, the scapula or omo^plat. Scapula, This is a flat, triangular, and asymmetrical bone, prolonged at its superior border by a flexible cartilage, articulated inferiorly with the humerus only, and applied against the lateral plane of the thorax in an oblique direction downwards and forwards. It has twofaceSy three borders, and three angles. Faces, — The external face is divided by the scapular or aero- mian spine, into two cavities of unequal width — the supra and infraspinous (or antea and postea spinatus)fossse. The spine is a very salient crest which runs the whole length of the external scapular surface; very elevated in its middle part, which shows an irregular enlargement — the tuhe^ rosity of the spine — it insensibly decreases towards its two ex- tremities. The supraspinous fossa, the narrowest, is situated above, or rather in front of the spine ; it is regularly concave from side to side, and perfectly smooth. The infraspinous fossa is twice the width of the pre- ceding, and occupies all the sur- face behind the spine. It ex- hibits: 1, Below, and near the posterior border, several rows of roughened lines for muscular insertion ; 2, Near the neck, the nutritious foramen of the bone, and some vascular grooves. The internal face is excavated in its centre to form a hollow called the subscapular fossa, which is prolonged superiorly by three diverging points. The median point extends to the superior border of the bone, and separates two roughened triangular surfaces destined for muscular implantation. Borders, — The superior is indented by an irregular groove to receive the inferior margin of the cartilage of prolongment. The latter is convex on its superior border, extends beyond the posterior angle of the bone, and gradually diminishes in thickness as it leaves its point of attachment. In old horses it is nearly always found partially ossified. The anterior border, thin and sharp, is convex in its superior two-thirds, and slightly concave for the remainder of its extent. The posterior is thicker and a little concave. THE BIGHT SCAPULA; OUTER SURFACE. 1, Antreior border ; 2, Superior margin for insertion of cartilage ; 3, Tuberosity of the spine ; 4, Antea- spinatus fossa; 5, Postea-spinatus fossa; 6, Neck of the scapula; 7, Coracoid process; 8, Glenoid cavity. THIS ANTEBIOB LIMBS, 73 Angles, — The anterior or cervical angle is the thinnest of the three. The posterior or dorsal angle is thick and tuberous. The inferior or humeral angle is the most voluminous, and is separated from the remainder of the bone by a slight constriction, which constitutes the nech of the scapula. It exhibits : 1, The glenoid cavity, an oval diarthrodial surface, excavated to a slight extent to receive the head of the humerus, notched on the inner side, and bearing on the external margin of the ridge which surrounds it a small tubercle of insertion; 2, The coracoid process, situated in front, and at a certain distance from the glenoid cavity. This is a large eminence in which may be distinguished two parts : the base, a thick rugged process ; and the summit, a kind of beak curved inwards. Structure and development. — Like all the wide bones, the scapula is formed of two compact lamellae separated by spongy tissue. The latter is very scanty towards the centres of the supra and infraspinous fossae, where it is often altogether wanting ; it is most abundant in p- ^^ the angles. The scapula is developed from two centres of ossification, one of which forms the coracoid pro- cess. ABM. This region has only one bone, the humerus. Humerus, The humerus is a long single bone, situated between the scapula and the bone of the fore-arm, in an oblique direction downwards and backwards. Like all the long bones, it offers for study a body and two extremities. Body c— The body of the humerus looks as if it had been twisted on itself from within to without in its superior extremity, and from without to within at the opposite end. It is irregularly prismatic, and is divided into four faces. The anterior face, wider above than below, has in its middle and inferior por- tions some muscular imprints. The posterior, smooth and rounded from one side to the other, becomes insensibly confounded with the neighbouring faces. The external is excavated by a wide furrow, which entirely occupies it, and turns round the bone ob- liquely from above to below and behind to before , it is to the presence of this channel that the humerus owes its apparent twist, and it is in consequence designated the furrow of torsion of the body of the humerus. This furrow is separated from the anterior face by a salient border, the anterior crest of the furrow of torsion, which ends inferiorly above the coronoid fossa, and superiorly, towards the upper third of the bone, by the imprint, or deltoid tuberosity. This is a Toughened, very prominent eminence, flattened before and behind, and inclining towards the furrow of torsion ; by its superior extremity it gives origin to a curved line which is carried backwards to join the base of the articular head. Near the inferior extremity, backwards and ANTERO-EXTERNAL VIEW OP RIGHT HUMERUS. 1, Trochlear or bicipital ridges; 2, External or deltoid tuberosity ; 3, Head or articular sur- face ; 4, External tuber- cle; 5, Shaft or body with its twisted furrow ; 6, 7, Articular or trochlear condyles ; 8, Ulnar fossa with a sulcus ; 9, Fossa for the insertion of the external lateral liga- ment. 74 THE BONES, Fig. 42. outwards, is seen the posterior crest of the furrow of torsion, whicli separates the latter from the posterior face of the bone. The internal face of the body of the humerus, rounded from side to side, is not separated from the anterior and posterior faces by any marked line of demarcation. It offers, near its middle, a depressed scabrous process for the insertion of the adductor muscles — teres major and great dorsal — of the arm. Towards its inferior third it shows the nutritive foramen of the bone. Extremities, — These are distinguished into superior and inferior. Both are slightly curved, the first backwards, the second forwards, a disposition which tends to give to the humerus the form of an S. The superior extremity is the most voluminous, and has three thick eminences ; a posterior, external, and internal. The first constitutes the head of the humerus; it is a very slightly-detached articular eminence, rounded like the segment of a sphere, and corresponding to the glenoid cavity of the scapula, which is too small to receive it entirely. The external eminence, named the trochiter, large trochanter, and great tuberosity, com- prises three portions, named the summit, convexity, and crest of the great tuberosity. The internal eminence, the trochin, little trochanter, or small tuberosity, also presents three distinct portions, which, by their posi- tion, correspond exactly with the three regions of the large trochanter ; these are so many muscular facets. The great •and small trochanters are separated from one another in front by a channel called the bicipital groove, because the superior tendon of the biceps muscle glides over it; it consists of two vertical grooves with a median ridge between them. The inferior extremity of the humerus has an articular surface corresponding to the radius and ulna. This surface, elongated transversely, convex from before backwards, and of greater extent within than without, exhibits two trochlea separated by an antero- posterior relief. The median or internal trochlea, the deepest, is limited internally by a kind of voluminous condyle, which corresponds to the inner lip of the humeral trochlea of Man. The external trochlea is bordered bercle and ridge; 5, outwardly by a slightly salient lip, which corresponds W; """"lof Condyloid ^"^ *>^ condyle of the humerus of Man. Above and fossa.' ' behind this articular surface is a wide deep fossa, the olecranian (or condyloid), so named because it lodges the rostrom of the olecranon in the extension movements of the fore-arm. It is bordered by two eminences, the external of which is less elevated than the internal. The first represents the epitrochlea, and the second the epi- condyle, of the humerus of Man. In front, and above the inner trochlea, there is another, but less spacious fossa, which receives the coronoid pro- cess during extreme flexion of the fore-arm, and which, for this reason, it would be convenient to designate as the coronoid fossa. Lastly, at the extremities of the transverse axis of the inferior articular surface is PO^ERIOR VIEW OF THE RIGHT HUMERUS. 2, External tuberosity •, 3, Articular head of the bone ; 4, External tu- THE ANTERIOR LIMBS. ^5 remarked : outwardly, an excavation for ligamentous insertion ; inwardly, a small tuberosity intended for the same purpose.^ Strudur ' and development. — The humerus, like all the long bones, is only spong-^ at its extremities. It is developed from six points of ossi- fication; oie of which alone forms the body, one the head and the small trochanter,^ another the large trochanter, a fourth the inferior articular surface, a fiith the epicondyle, and the last for the epitrochlea. The latter is sometimes absent. FORE -ARM. This region has for its base two bones, the radiuB and cubitus (or ulna) united into a single piece at an early period in most of the domesticated animals. 1. Madius. This is a long bone, placed in a vertical direction between the humerus and the first row of carpal bones, and divided into a hody and two extremities. Body. — Slightly arched and depressed from before to behind, the body presents for study two faces and two borders. The anterior face is convex and perfectly smooth. The posterior, a little concave from one extremity to the other, offers : 1, Near the external border, a triangular surface, covered with asperities, elongated vertically, very narrow, commencing near the upper fourth of the bone and terminating in a fine point towards the lower fourth : this surface is brought into contact with the anterior face of the ulna by an interosseous ligament, which is completely ossified before the animal reaches adult age ; 2, Above, there is a wide, transverse, but shallow groove, which aids in forming the radio-ulnar arch and shows, near the point where it touches the preceding surfaee, the nutrient foramen of the bone; 3, Near the internal border, and towards the inferior third, there is a ver- tically elongated and slightly salient eminence of insertion. The two borders,, external and internal, are thick and rounded; they establish an insensible transition between the faces. Extremities. — The superior is larger than the inferior. It has : 1, An articular surface elongated from one side to the other, concave from before to behind, wider within than without, and moulded to the articular surface of the inferior extremity of the humerus ; there is also seen, outwardly, a double gorge which receives the two lips of the external trochlea ; in the middle, an anteroposterior ridge which is received into the internal trochlea ; within, an oval cavity corresponding to the internal border of the former ; 2, The external tuberosity, placed at the extremity of the great diameter of the articular surface ; it is prominent and well detached ; 3, The internal or bicipital tuberosity, a large, very rugged, and depressed process, situated within and in front of the glenoid cavity ; 4, A little lower, and on the same side, there is a strong muscular and ligamentous imprint, separated from the preceding tuberosity by a transverse groove intended for the passage of a tendinous branch ; 5, The coronoid "process,^ a small conical eminence, at the summit of which terminates, anteriorly, the median ridge of the articular ' The articular surfaces which, in veterinary anatomy, have received the names of trochlea and condyle, not being the same as in human anatomy, there results an annoying inversion of the situation of the epitrochlean and epicondyloid eminences, so named. It has therefore been our endeavour to remedy the improper employment of these denominations, which has been a cause of error in comparative anatomy. 2 In Man this belongs to the ulna. 76 THE BONES, Fig. 43. surface; 6, Two diarthrodial facets elongated transversely, Sut on the posterior outline of the large articular surface, with which th y are con- founded by their superior border ; the/ correspond to similar facets on the ulna ; 7, Be ow these, a roughened surface which extends to the radio- ulnar arch, and is in contact with ai analogous surface of the same bone through the medium of an interosseous ligament ; in the Horse this liga- ment rarely ossifies. The inferior extremity, flattened from before to behind, presents: 1, Below, an articular sur- face elongated transversely and somewhat irregu- lar, responding to the four bones in the upper row of the carpus; 2, On the sides, two tube- rosities for ligamentous insertion, the internal salient and well circumscribed, the other external and excavated by a vertical fissure, in which passes a tendon; 3, In front, three grooves for the gliding of tendons ; the external is the largest, and vertical like the median; the internal, the nar- rowest, is oblique downwards and inwards; 4, Posteriorly, a strong transverse ridge which sur- mounts the articular surface and serves for the insertion of ligaments. Structure and development. The radius is a very compact bone, and is developed from three centres of ossification : one for the body and two for the extremities. 2. Ulna. This is an elongated, asymmetrical bone, in the form of an inverted triangular pyramid, applied against the posterior face of the radius, to which it is united in adult solipeds. It offers for des- cription a middle portion and two extremities. Middle 'portion, — This has three faces wider above than below, and three borders which become joined at the inferior extremity of the bone. The external face is smooth and nearly plane. The faces for the humerus; 7, internal is also smooth and slightly hollowed. ^^'f^^\ l^'^f^i'^^'A- ^' The anterior is formed to correspond to the radius, Shaft or body of the radius ; ^ . t "-x- i , ,^ A 9 Grooves for tendons. ^^^ presents peculiarities analogous to those of the posterior face of that bone. Thus there is found in proceeding from above to below: 1, Two small diarthrodial facets ;^ 2, A rough surface ; 3, A transverse groove for the formation of the radio-ulnar arch; 4, A triangular surface, studded with rugosities, which occupies the remainder of the bone to its lower extremity. The lateral borders, external and internal, are sharp, and, like the anterior face, are in contact with the radius. The posterior border is concave, rounded, and thicker than the other two. Extremities, — The superior extremity comprises all that portion which exceeds the articular surface of the radius. It constitutes an enormous ^ It is represented iu Man by the smaller sigmoid notch, EXTERNAL FACE OF THE RADIUS AND ULNA. 1, Ulna; 2, Point of the ole- cranon ; 3, Beak of the ole- cranon ; 4, Radio-ulnar arch ; Supero-external tuberosity ; 6, Radio-ulnar articular sur- TEE ANTEBIOB LIMBS, 77 Fig. 44. process — the olecranon — flattened on both sides, and presenting: 1, external face, slightly convex; 2, An internal excavated face; 3, anterior border, thin and sharp superiorly, notched below to for mthe sigmoid cavity ;^ an articular surface concave from above down- wards, rounded from one side to the other, which corresponds with the humeral cavity, and is surmounted by a salient prolongation named the beak of the olecranon ; 4, A con- cave and smooth posterior border; 6, The summit, a kind of thick roughened tuberosity which terminates the olecranon above, and into which are inserted the extensor muscles of the fore-arm. At its inferior extremity, the ulna ends, towards the lower fourth of the principal por- tion of the fore-arm, in an acute point, and sometimes by a small knob (capitulum ulme). It is not rare to see it prolonged, especially in the Ass and Mule, to the inferior external tuberosity of the radius. This tuberosity then appears to belong to it, at least in part ; and all that portion which is situated behind its vertical groove might be justly considered as belonging to the ulna. Structure and development, — The ulna con- tains much compact tissue, even in the region of the olecranon; it is also very solid. It is an imperfect bone, developed from two centres of ossification only, one of these being for the apex of the olecranon. FORE-FOOT OR HAND, The anterior foot, or hand, is the region which presents the greatest differences when it is inspected in the various individuals of the animal series. Nevertheless, in all the mam- malia the constitution of the hand is funda- mentally the same, and may be divided into three sections: the carpis, metacarpus, and phalangeal region. The hand is formed by ^ve parallel or quasi-parallel rays that constitute the digits, each of which is effectively or virtually com- posed of two superposed carpal, a metacarpal, and three phalangeal hones, forming altogether the digit, properly so called. But this typical composition, established through the labours of MM. Joly and Lavocat, is rarely found to An An RIGHT FORE-FOOT OF A HORSE. 1, Radius ; 2, Groove for the an- terior extensor of the phalan- ges 5 3, Seaphoides •, 4, Lunare ; 5, Cuneiform ; 6, Trapezium ; 7, Magnum ; 8, Unciform ; 9, Metacarpal ; 10, Small meta- carpal; 11, Sesamoid bone; 12, Suffraginis; 13, Coronary; 14, Navicular; 15, Pedal; 16, Its ala. be realised in a complete manner. The following is what is presented in the hand of Man, who is the most ^ The greater sigmoid cavity of Man. 78 THE BONES. perfect pentadactylous type. The carpus is composed of eight bones, the metacarpus of five small, parallel, bony columns ; the phalangeal region of five digits— thumb, index, medius, annularis, and auricular is, formed each of three phalanges, with the exception of the thumb, which has only two. In the domesticated animals, the constitution of the hand is more or less removed from this type, in consequence of abortive development, which diminishes either the number of rays, or the number of pieces composing these. Thus, in the Gat and Pig there are eight bones in the carpus ; but in the Dog and Horse there are no more than seven ; in the Ox and Sheep there are only six, for in them two or three bones are fused together. The metacarpus of the Dog and Cat has certainly five metacarpal bones, but the metacarpus of the Pig has no more than four, that of the Horse three, and that of Buminants only two. In the metacarpus of the Pig the fifth bone is not developed. In the Horse it is entirely absent ; the fourth and first are independent, and the third and second are confounded to form a voluminous bone which has been named the principal (or large) metacarpal. In Buminants, the fourth and fifth metacarpals are quite imperfect, the first being arrested in its development, and the second and third becoming consolidated as in the horse. Lastly, it is noted that the digital region of Carnivora has ^ye digits, the Pig four, Buminants two, and Solipeds only one. In the Pig, the thumb is undeveloped; in ruminants it is completely absent, and the first and fourth are represented by two small bones situated behind the metacarpo- phalangeal articulation ; while in solipeds the single digit abeady mentioned results from the fusion of the auricularis and medius. From this preliminary synthetical exposition, it will be easy to understand the description of the bones composing the hand in solipeds. 1. Carpal Bones, The carpus forms the base of the hand. Situated between the inferior extremity of the radius and the superior extremity of the metacarpal bones, it is composed of several small bones joined to each other in the fresh state by extremely solid articular bands. Collectively, they form an almost quadrilateral mass in which may be distinguished two faces and four borders. The anterior face is slightly convex from side to side and irregular ; it corresponds to the tendons of the extensor muscles of the metacarpus and phalanges. The posterior face is very unequal and converted, especially outwardly, into a groove in which the tendons of the flexor muscles of the phalanges glide. The superior border articulates with the radius ; the inferior border with the metacarpal bones. The lateral borders are nearly level ; above and behind the external border is remarked a considerable eminence, formed by the bone which will be hereafter studied as tKe supercarpal bone (or trapezium). In the carpus of the Horse are seven bones, which are disposed in two superposed rows. The superior row comprises four bones placed side by side, and designated by the numerical names of first, second, third, and fourth^ viewing them from without to within. The inferior row has only three, which are named in the same manner. THE ANTERIOB LIMBS, 79 In applying to them the names proposed by Liser, we have, in the upper tow: 1. The pisiform, or supercarpal bone (trapezium); 2. The pyramidal (or cuneiform) bone ; 3. The semilunar (or lunare) bone 4. The scaphoid bone ; In the inferior row : 1. The hook or unciform bone ; 2. The great bone or capitatum (magnum) ; 3. The trapezoid bone.^ The description of these bones is most simple, and may be made in a general manner for all. Thus, with the exception of the supercarpal bone, they are solids, nearly cubical in form, and exhibit on their periphery : 1, Articular surfaces ; 2, Surfaces of insertion. The articular surfaces represent small, flat, or slightly-undulating facets, distributed on the superior, inferior, and lateral surfaces ; none are found in front or behind. The superior and inferior faces are entirely occupied by a single facet which responds either to the radius, the metacarpal, or to the bone of the other row. The lateral facets are always multiple and in contact with the bones of the same tier ; they do not exist, of course, on the eccentric side of the first and third bones of the superior or inferior rows. The surfaces of insertion are absent on the superior and inferior faces ; they separate, in the form of roughened fossae, the lateral articular facets. Before and behind they are covered by more or less marked rugosities. Bones of the Upper or Antibrachial Eow. — The first, or os pisiforme, is without the row ; it is situated above and behind the carpus, from whence its name of supercarpal hone, by which it is usually known in veterinary anatomy. This bone, which merits a special description, represents a disc flattened on both sides, offering for study two faces and a circumference. The external face is convex, roughened, and channeled anteriorly by a groove that traverses it from above to below, and in which glides the inferior tendon of the external flexor of the metacarpus. Its internal face, smooth and concave, concurs to form the external wall of the carpal sheath. The circumference presents, in front, two articular facets : the superior, concave, corresponds to the radius ; the inferior, convex, is in contact with the second bone of the upper row. The other three bones of this row increase in volume from without to within. The second, or os pyramidalis (or cuneifonn), responds to the radius, the first bone of the lower row, the third of the upper, and the supercarpal bone ; it has in all five articular facets. The third, or os semilunare {lunare), has six facets, and is united below to the first and second bones of the second row. ^ The analogue of the trapezium of Man is not found in the Horse. According to M. Lavocat, we ought to regard as such a small supernumerary bone sometimes seen articu- lating behind the third bone. We are entirely of his opinion. (Leyh is also of this opinion, and states that this supernumerary bone is more frequently found in large common-bred horses. Stubbs, in his old, but fine ' Anatomy of the Horse,' does not refer to it, but describes the seventh bone as the pisiform. Percivall says the supernumerary bone is not invariably present, and that sometimes two are found. He designates Stubbs* and Chauveau's pisiform bane as the trapezium. Girard names the supernumerary bone the " pisiform " or pea-shaped. When one or more of these osseous nodules are present, they represent the poUex and fifth digit of the human hand.) 80 TEE BONES. The fourth, or os scaphoides, the most voluminous of the row, has only four facets, and articulates by its inferior face with the os magnum and Collectively, the second, third, and fourth bones of the upper row form two articular surfaces. The superior, or radial articular surface, is very irregular ; but in ex- amining it from without to within there may be observed: 1, A glenoid cavity on the pyramidal bone ; 2, In front, a transversely-elongated condyle Fig. 45. Fig. 46. POSTERIOR VIEW OF THE RIGHT CARPUS. 1, Second cuneiform, or pyramidalis ; 2, Third, or lunare ; 3, Fourth, or sca- phoides; 4, First, supercarpal, pisiform, or trapezium ; 5, First of lower row, or unciform; 6, Second, or magnum; 7, Third, or trapezoides j *, *, Small metacarpal bones. FRONT VIEW OF RIGHT CARPUS. 1, Second of upper row, or cuneiform ; 2, Third, or lunare; 3, Fourth, or scaphoides; 4, First, supercarpal, or trapezium ; 5, First of second row, or unciform ; 6, Second, or magnum ; 7, Third, or trapezoides. on the semilunar and scaphoid bones ; 3, A groove placed behind the pre- ceding condyle. The inferior articulating surface, which corresponds to the second row, is constituted by several undulated facets ; it is convex outwardly and in front, concave posteriorly and inwardly. Bones of the Inferior or Metacarpal Eow. — The thickness of these bones decreases from without to within. The jfirst, unciform, or hookhone (os Jiamatum), has four diarthrodial facets, and responds, above, to the two first bones of the superior row ; below, to the first and second metacarpals. The second, os magnum, or os cajpitatum, the largest, has seven articular facets, three of which are on the interno-lateral face. It articulates, above, TEE ANTEBIOB LIMBS. 81 with \h^ semilunar and scaphoides ; below, with the principal metacarpal and the internal rudimentary metacarpal. The thirds or trapezoides, the smallest, is provided with five facets, and is in contact with the scaphoides above, and the middle and internal meta- carpals below. Collectively, these bones of the lower row form two Fig. 47. large diarthrodial surfaces. The upper surface responds ^ j to the bones of the upper row, and is constituted in front, and from without to within, by a small condyle and two glenoid cavities; behind, by two isolated condyles, formed by the os magnum and the tr.ipezoides. The inferior articular surface is only formed by more or less long and plane facets, which incline towards each other. It corresponds to the three portions of the metacarpus. Structure and development, — Each carpal bone is formed by a nucleus of close spongy substance enveloped in a layer of compact tissue. Each is developed from a single centre of ossification. 2. Metacarpal Bones. In Solipeds, the metacarpus is composed of three bones, named the " metacarpals," standing parallel to each other. These are the principal metacarpal and the two rudimentary metacarpals, an external and internal. Principal Metacarpal. — This is a long cylindrical bone, situated vertically between the carpus and the digital region. Body. — The body is a little depressed before and behind, a disposition which permits it to be described as having two faces and two borders. The anterior face is perfectly smooth and rounded from side to side. The posterior face is fiat, and exhibits : 1, Towards the upper third, the nutritive foramen of the bone; 2, On the sides, two narrow, roughened surfaces, parallel and elon- gated vertically, commencing near the superior extremity to disappear a little below the middle of the bone ; these surfaces are held in apposition with the rudimentary metacarpals by means of an interosseous ligament which is often ossified in old horses. The borders, external and internal, are very thick, round, and smooth, like the an- terior face. Extremities. — The superior is fiattened before and behind, and presents : 1, Above, an undulating articu- latory surface, formed by the union of several fiat facets more or less inclined on one another : they respond to all the lower row of carpal bones ; 2, An- teriorly and inwardly, a tuberosity for muscular inser- tion ; 3, Posteriorly, and directly above the roughened surfaces of the posterior face, four small diarthrodial facets in pairs, and running into the larger articular surface by their superior border: they are adapted to similar facets on the rudimentary metacarpals. The inferior extremity, elongated transversely, corresponds to the first phalanx and the large sesamoids by an articular surface, convex from before to behind, which POSTERIOR VIEW OF RIGHT METACARPUS. 1, Head of large meta- carpal bone for ar- ticulation with the trapezoides, mag- num, and unciform ; 2, Inner splint, or small metacarpal bone, for articula- tion with the trape- zoides; 4, Scabrous surface for the at- tachment of the sus- pensory ligament ; 5, Nutrient fora- men ; 6, Median ridge separating the two inferior con- dyles. 82 THE BONES. is composed of two lateral condyles separated by a median spine. The two condyles would be exactly alike, if the antero-posterior diameter of the external condyle was not less extensive than that of the opposite condyle. Both are hollowed on the sides by an excavation for the attachment of ligamentous fasciculi. Structure and development, — ^The principal metacarpal is one of the most compact bones in the body. It is developed from two centres of ossification, one of which is for the inferior extremity. KuDiMENTARY METACARPALS. — The two rudimentary (small) metacarpal (or splint) bones are elongated, and placed against the posterior face of the principal bone, one without, the other within. Each is in the form of an inverted pyramid, and exhibits a middle jpart and two extremities. Middle portion, — Prismatic and triangular, this offers: 1, Three faces, — an external, smooth and rounded from one border to the other ; an internal, plane, and equally smooth ; an anterior, covered with asperities to give attachment to the interosseous ligament uniting the lateral metacarpal bone to the median ; 2, Three salient borders which markedly separate the faces from each other. Extremities, — The superior, the largest, is named the head, and shows : above, a diarthrodial facet which corresponds to one or two bones of the inferior row of the carpus ; in front, other two small facets continuous with the pre- ceding, and in contact with similar facets on the median metacarpal bone ; on the other points of its periphery are rugosities for the attachment of ligamentous and tendinous fibres. The inferior extremity only reaches to about the lower fourth of the large metacarpal bone, and terminates in a small enlargement or button, which is never consolidated with the latter. The two lateral metacarpals, although very much alike, may yet be easily distinguished from each other. For instance, the internal bone is always the thickest and often the longest ; besides, the superior articular surface of its head results from the union of the two facets corresponding to the two last carpal bones of the lower tier. Structure and development. — Of a somewhat compact texture, like all the long bones, these have no medullary canal, and are developed from only one ossific centre. Not unfrequently, however, the tubercle is formed from a special centre. 3. Bones of the Phalangeal Begion or Digit, Solipeds have only one digit, supported by the principal metacarpal bone, and composed of three pieces placed end to end, one upon another. The first comprises three bones : a principal, the first phalanx, and two com- plementary ones, the sesamoids. The second is formed by the second phalanx, and the last, which terminates the limb, is constituted by the third phalanx and an accessory bone which has received the name of the small sesamoid (navicular hone). First (proximal) or Metacarpal Phalanx. — The first phalanx (or pastern hone), the smallest of all the long bones, is situated in an oblique direction from above downwards, and behind to before, between the principal metacarpal and the second phalanx. Body, — Depressed in front and behind, this bone exhibits : an anterior face, round from one side to the other, and slightly roughened above and below ; a posterior face, flat, covered with ligamentous imprints in the form of a triangle with the base reversed ; two lateral horders, thick, rounded, and provided with some imprints. THE ANTERIOB LIMBS. 83 Extremities, — The superior, the largest, presents: Above, an articular surface adapted to the inferior metacarpal surface, and consequently composed of two glenoid cavities separated by a groove running from front to back ; laterally, and a little posteriorly, a well-defined tubercle of insertion. The inferior extremity has a transversely elongated articular surface to cor- respond to the second phalanx; this surface is formed by two condyles separated by a middle groove, and surmounted laterally by a small tuberosity for ligamentous insertions. The external condyle is smaller Fig. 48. LATERAL VIEW OF THE DIGITAL REGION •, OUTSIDE OP RIGHT LIMB. 1, Large metacarpal bone; 2, 3, Outer and inner sesamoids ; 4, First, proximal, sulfraginis or metacarpal phalanx, 5, Its posterior surface ; 6, Tuberosity for ligamentous insertion ; 7, Inner condyle of ditto ; 8, Eminences on second pha- lanx for attachment of lateral liga- ment; 9, Smooth surface for passage of deep flexor tendon on second pha- lanx ; 10, Imprint for the insertion of the tei-minal branch of the perforatus tendon; 11, Navicular bone; 12, Third phalanx, pedal, or coffin bone ; 13, Its basilar process. Fig. 49. POSTERIOR VIEW OF FRONT DIGITAL REGION. 1, Large metacarpal bone ; 2, 3, Outer and inner splint bones ; 4, 5, Sesamoid bones ; 6, SufFraginis ; 7, 8, Tuberosi- ties for insertion of crucial ligaments ; 9, Triangular space for insertion of short sesamoid ligament ; 10, Anterior face of suffraginis ; 11, 12, Tuberosities for ligamentory insertion ; 13, Articu- lar depression separating condyles ; 14, 15, Second phalanx ; 16, Scabrous sur- face for ligamentous attachment*, 17, Smooth surface for gliding of deep flexor tendon ; 18, Navicular bone ; 19, Pedal bone; 20, Basilar process; 21, Plantar foramen. tban tbe internal, and wben tbe bone is placed upon a horizontal plane, the anterior face turned upwards, it only touches by three points — the two tubercles of the upper extremity and the internal condyle ; by pressing on the external condyle, it is easy to make the bone rock. ^ The first phalanx is a very compact bone, and is developed from two points, one of which is for the superior extremity alone. 84 TEE BONES'. Sesamoids. — These are two small short bones placed side by side behind the superior extremity of the first phalanx, whose articular surface it completes, as it has not extent enough to be exactly adapted to the metacarpal surface. Each of these bones represents a small, irregularly- shaped polyhedron, or rather, a short trifacial pyramid. It offers : an anterior face, which is articular, and corresponding to the inferior extremity of the principal metacarpal bone, moulded, as it were, on one of the condyles and one of the sides of the median ridge ; a posterior face, covered with cartilage in the fresh state, and forming, with that of the opposite bone, a gliding concave surface for the flexor tendons of the phalanges ; a lateral face, studded with ligamentous imprints ; a summit, directed upwards ; and a base, turned downwards, and serving for the attachment of several ligaments. Second (or Middle) Phalanx (Os Corona, Small Pastern Bone). — This is a short bone, situated in the same oblique direction as the first phalanx, and between it and the third. Its general form is that of a cube flattened before and behind, and offering the following features : an anterior face, covered with some slight imprints ; a posterior face, provided, above, with a transversely elongated gliding surface ; a superior face, channeled by two glenoid cavities, to match the inferior articulating surface of the first phalanx ; an inferior face, formed on the same plan as the last, being occupied by two unequal condyles which articulate with the third phalanx and the navicular bone ; two lateral faces exhibiting a very marked imprint. In the interior of this bone is found a nucleus of very condensed spongy substance, enveloped in a layer of compact tissue. It is usually developed from a single centre of ossification ; though in many subjects there is a complementary nucleus for the superior articular surface and the posterior gliding surface. Third (Distal) Phalanx, Os Pedis (or Pedal Bone). — This is a short bone which terminates the digit, and sustains the hoof that incloses it and the navicular bone. When completed by a special fihro-cartilaginous apparatus, it represents the segment of a very short cone, obliquely truncated behind, from the summit to the base. It offers for study : three faces, three borders, and two lateral angles Faces, — The anterior, convex from side to side, and cribbled by porosities and vascular openings, shows on each side : 1, ^^* * The preplantar fissure, a horizontal groove more or less ramified, which commences behind, between the retrossal and basilar processes, ter- minating in front in one of the foramina which penetrate the bone; 2, The patilobe eminence, a roughened projecting surface, situated between the preceding fissure and the inferior border of the bone. The superior face is occupied by an articu- lar surface formed by two glenoid cavities and a slight median ridge ; it comes in apposition with PLANTAR SURFACE OF THIRD ^^ infcrior facc of tho second phalanx. The PHALANX. inferior (or solar) face, hollowed out like an arch, 1, Lower face, or sole ; 2, 3, is divided into two regions by the semilunar crest, Wings, or retrossal pro- q, salient line which describes a curve forwards. rStt'r forr^'"' The anterior region is perforated with very fine / porosities, and corresponds to that part oi the hoof named the sole. The posterior region shows, immediately behind the semilunar crest, a median imprint, and two lateral channels designated the THE ANTEBIOB LIMBS. 85 plantar fissures. These originate at the root of the basilar process, are directed obliquely downwards and inwards, and open into the plantar fora" mina, the external orifices of two large canals which enter the bone and unite in its interior to form the semilunar sinus. Borders, — The superior describes a curve, with the convexity forward, and presents : 1, In its middle, the pyramidal eminence of the os pedis* a single triangular process, flat before and behind, roughened on its anterior aspect, and concurring, by its posterior surface, to form the articular surface which responds to that of the second phalanx , 2, Laterally, two facets of insertion which encroach on the anterior surface, and even advance, posteriorly, nearly to the preplantar fissure. The inferior border is thin, dentated, convex, and semicircular; it is perforated by from five to ten large foramina which pass into the bone. The posterior border is slightly concave ; on it is observed a very narrow, transversely elongated, diarthrodial facet, which becomes confounded with the superior large articular surface, and is adapted to a similar facet on the navicular bone. Lateral angles. — These are two projections directed backwards, on whose summit the three borders of the bone unite, and which gives attachment to the lato]iil fibro-cartilages. A deep notch, the origin of the preplantar fissure, separates each into two particular eminences : one, the superior, named by M. Bouley the basilar process ; the other, the inferior, prolonged behind, and designated by Bracy Clark the retrossal process, from retro, behind, and osm, bone. Structure. — The os pedis exhibits in its interior the semilunar sinus, a cylindrical, transversely elongated, and semicircular cavity resulting from the arching anastomoses of the two plantar canals. From this cavity pass off numerous channels, which anastomose frequently with each other, and open externally by the foramina on the anterior face of the bone, or by those on its inferior border. The os pedis has for its base a nucleus of spongy substance, surrounded by a layer of compact tissue. The latter is thicker towards the pyramidal eminence than elsewhere, and sends into the interior numerous prolongations which form the walls of the semilunar sinus, as well as the bony channels which spring from it. Development. — The third phalanx, formed from a single nucleus of ossification, undergoes numerous changes in its configuration during life. Thus, in the young animal the lateral angles are thick, obtuse, and but little prolonged posteriorly ; but as it growls older, they increase in length and become salient. The development they then assume is due to the progressive ossification of the lateral cartilages implanted on their surface. It often happens, in -very old horses, that this ossifying process is carried to an extreme degree, and nearly the whole substance of these complementary organs is invaded. From the commencement, its inevitable result is to convert the notch which separates the basilar from the retrossal process into a foramen. The complementary fibro-cartilaginous apparatus of the os pedis. — To understand properly the disposition of this portion of the foot, it is necessary that a previous knowledge of the ligaments and tendons attached to the os pedis should have been obtained ; therefore a detailed description will only be given when the Horse's foot is studied as a whole. It will be sufficient here to state that this apparatus consists of two lateral pieces, the fibro- cartilages of the OS pedis, united behind and below by the plantar cushion, 2k fibrous and elastic mass on which rests the navicular bone through the medium of the perforans tendon. 86 THE BONES, The Small Sesamoid (or Navicular) Bone. — This short bone is annexed to the third phalanx, behind which it is situated ; it is elongated transversely, flattened above and below, and narrowed at its extremities. It offers : 1, A superior face, on which are prolonged the glenoid cavities and the median ridge of the articular surface of the os pedis ; it responds to the second phalanx ; 2, An inferior face, divided by a slight relief into two undulated facets, and covered with cartilage -(i to form a gliding surface ; 3, An anterior border, channeled length- b }' ways by a groove of insertion, above NAVICULAR BONE. which is remarked a diarthrodial a, Upper, or articular surface; 6, inferior border; ^acet that brings the small sesa- c, Superior border; d, Inferior, or posterior moid into Contact with the pOS- surfiice ; e, The median transverse ridge ; /, terior border of the third phalanx ; Inferior margin;^, Superior margin. 4^ ^ posterior border and two ex- tremities, for ligamentous insertion. This bone, as well as the sesamoids, originates from a single centre of ossification. It is formed of a layer of compact tissue enveloping a nucleus of very condensed spongy substance. DIFFERENTIAL CHARACTERS OP THE ANTERIOR LIMB IN OTHER THAN SOLIPED ANIMALS. A. Shoulder. — In Carnivnra the shoulder is composed of two bones, these creatures being furnished with a clavicle. This bone in the Dog is a little osseous shell itnbedded among the muscles situated in front of the scapulo-humeral angle. That of the Cat constitutes a small fet)'loid bone, which is joined to tlie acromion and sternum by two ligamentous cords. In all the domesticated animals except Solipeds, the coracoid process is immediately applied against the glenoid cavity. In all, aLo, with the exception of the Pig, the scapular spine gradually rises from above to below, and terminates in a sharp salient point, the acromion. The spine partitions the external face of the bone into two equal fossae in the Dog, and in Ruminants into two fossse, which, for extent, are as one to three to each other. The scapular spine of the Pig is much elevated towards the middle part, and bends more or less backwards, In the Carnivora the prolonging cartilage is entirely absent ; the anterior border of the scapula is very convex, as if the bone had been curved downwards. In the other domesticated mammals the scapula is somewhat regularly triangular. B. Arm. — Proportionately, the humerus is longer, and mf)re inflected like an S, as the number of apparent digits is increased. Therefore it is that in the Carnivora the characters of length and inflexion are most marked. In the Ox, tSheep, Pig, and Dog, the furrow of torsion is not so deep as in the Horse, and the deltoid imprint is less salient. In the Dog this imprint is represented i)y a large roughened surface; in the Pig by some asperitifs only. The nutrient foramen is on the posterior face. It has been .stated that the medullary canal in the Ox is traversed by an osseous band; but the presi nee of this is not constant. The summit of the trochiter is very elevated, particularly in Ruminants, and is thrown back on the bicipital groove, which is single; in tlie Dog and Pig, this groove is carried inwards above the intern il face of the humerus. The external trochlea in the Ox and Pig is well marked. In Camivora, the inner lip of this trochlea is very high, and the external lip incomplete; a foramen establishes communication between the olecranian and coronoid fossae. In the Cat there is found, on the inner side of the lower extremity, a particular foramen that forms a vascular arch. C. Fore-ahm. — The fore-arm is short in the Ox, Sheep, and Pig , very long in the Carnivora. The principal differential characters that it presents are connected with the relative dimensions of the two bones and their m'de of union. Regarding these, and as generally Applicable, tj^e following principles may be laid down : — 1. T'te development of the ulna is in direct relation to the division of the foot. — Mono- dactyloub animal, such as the Horse, Ass, and Mule, have in fact only a rudimentary THE ANTJEMIOR L1MB8. ulna. In the perntadactylous animals, as Man, the Cat, etc., on the contrary, this is a veritable long bone which equals, or even exceeds, the radius in volume. 2. The closeness of union between the radius and tdna is in increased proportion as the animal exclusively employs its inferior extremity fur standing or walking. — Thus, in Solipeds and Rumi- nants, and Pachyderms in general, the two bones are consolidated, or at k ast united, by an interosseous ligament, and in so firm a manner that they can only execute very obscure movements on each other. The anterior limb of these animuls is indeed only used to support the body on the ground. In those, on the con- trary, which may employ it to dig up the soil, climb on trees, etc., or as an organ of prehension, the radius and ulna are merely joined at their extremities by an articulation, which permits them to move upon ^ne another with the greatest facility. Rodents, the majority of the Carnivora, and the quadrumana, are so provided ; but it is in Man that the relative independence of the two bones is carried to the highest de,ij:ree. No animal can so easily execute the movements of pronation and supination of the hand, which are determined by the play of the two bones of the fore-arm on each other. To the indication of these fundamental characters may be added some details on a few particular and important points. In all the domesticated animals other than Solipeds, the ulna is developed from three ossifying centres, extends the whole length of the radius, and concurs to form the articular surface correspond- ing to the carp'cil bones. It is an elongated bone in Ruminants, and a long bone, hollowed by a medullary canal, in the Pig and Carnivora. The inferior articular surface of the bone of the fore-arm in Ruminants is cut obliquely from above to below, and from with- out to within. In these animals we find the radius very flat from before to behind, the bicipital tuberosity scarcely noticeable, and two radioulnar arcades united externally by a deep fissure. The union of the two bones is more intimate than in the Horse, for the ossification always finishes by invading that portion of the inter- osseous ligament placed above the superior vascular arcade. In the Pig, the ulna is flattened from before to behind, and spread out on the posterior face of the radius, which it almost completely covers. Its olecranon is very prominent. In the Dog and Cat, the two bones of the fore-arm are nearly equal in volume, and are slightly crossed in an X fashion. The superior extremity of the ulna is thicker than its lower extremity ; it is nearly the opposite of this in the radius. Movable on one another, these bones only touch by their extremities, and to this effect offer : 1, Alx)ve, on the ulna, a concave articular surface, the small sig- moid cavity, and on tl)e radius a rounded hinge-like facet; 2, Below, on the radius, a concave surface, and on the ulna a convex one. D. Fore-foot, or hayd.— 1. Carpal hones, — The carpus of the P^gf, like that of Man, contains eij^ht bones— four in each of the rows. The second bone of the upper row corresponds with the ulna, and to a sma)l extent with the radius. In tlie bones of the lower row, it is obsierved that the first corresponds with the two external meticarpals, the second with the great internal metacarpal, the third with the preceding and the small internal metacarpal. The foui th, or trapezium, terminates inferiorly by a blunt point, and has no relations w.th the metacarpal bones, because the thumb is entirely undeveloped in this animal. 87 .52. 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, First and second bones of the lower row ; 9, Rudimentary metacar- pals ; 10^ Principal metacarpals; 11, External digit; 12, Internal di^it. ^9 ^ FORE-ARM AND FOOT OF THE OX ; FRONT VIEW. 88 TEE 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 supercarpal bone, elongated, prismatic, and thickened at its extremities, offers in front two coalescing articular facets, one to correspond with the ulna, the other to join the pyramidalis. The bones of the inferior row decrease in thickness from the first to the fourth, and correspond: the first, to the first and second metacarpals; the second, to the metacarpal of the third digit ; the third, to that of the fourth digit ; the Fig. 53. fourth, to the metacarpal of the thumb. .3, In the Dog there are only seven bones, as the scaphoid and semilunar bones are united, but the general disposition is the same as that in the Cat. Lastly, in the Ox and iSheep the carpus is only composed of six bones : four in the upper row, and only two in the lower, where the os magnum and trapezoides afe consolidated. The supercarpal bone has no groove for gliding, and the pyramidalis articulates with the radius and cubitus. The bones of the lower row only articulate with the principal metacarpal bone. (Professor Gobaux, in 1865, exhibited specimens which go to prove that of the two bones of the lower row in the carpus of Euminants, the internal really represents two; so that these animals actually have seven carpal bones like the Horse.) 2. Metacarpal bones. — The number of metacarpal bones varies much in the domesticated animals : — In the Carnivora there are 5 In the Pig there are . . . . . . .4 In Kuminants there are 2 The five metacarpals of the Dog and Cat articulate with each other, at their superior extremities, by lateral facets; 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. w -trif v!»^ The four metacarpals of the Pig articulate with each other, In ra i\ ^® ^^ *^® Carnivora. The second and third are larger than the J If \| ll first and fourth. The fifth metacarpal is not developed. Tf I I vL ^^ Buminants the metacarpal bones are two in number : «jf J Ll ^ a principal, which itself results from the consolidation of the if f \ I / 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 rORE-ARM AND FOOT OF of the primitive separation of the bone in two pieces. This THE DOG ; ANTERIOR fissuro presents, inferiorly, the anterior orifice of a canal that TACE. completely traverses the bone. The posterior face is also 1, First digit ; 2, Second marked by a very slight longitudinal groove. Tlie superior digit ; 3, Third digit ; 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 single bones of the lower row surface in the Horse ; each corresponds to one of the digits ; of carpal bones 5 10,11, the external is always smaller than the internal. In the First and second bones foetus, the two long bones that form the great metacarpal of the upper row 5 12, are simply laid together, and their medullary canals are sepa- Supercarpal bone ; 13, rated from each other by the double partition which results Body of the ulna ; 14, from this apposition ; after their coalescence, however, tl]e par- Apex of the olecranon ; titions are completely destroyed by resorption, and in a short time there is only a single medullary canal for the entire bone. The rudimentary metacarpal 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 la sometimes absent in the Sheep and Goat, ^ 4, Fourth digit; 5, Thumb; 6, 7, 8, 9, First second, third, and fourth 15, Beak of the olecra- non; J 6, Body of the radius. TEH: ANTEBIOn LIMBS. 89 *6. Digital Region. — In the domesticated animals the number of complete digits is as follows : — Carnivora . . . , . 5 Pig 4 Kuminants 2 The five digits of the Dog and Cat are exactly analogous to those of Man. Thus, the external corresponds to the auricularis, the second to the annularis, the third to the medius, the fourth to the index, and the internal to the thumb. — The latter, very small, has only two phalanges and does not come into contact with the ground. Each of the first four is composed: 1, Of a first phalanx, to which are annexed two sesamoids; 2, A second phalanx, which yet represents a veritable long bone ; 3, A conical phalan- gette, pointed, bent downwards, and hollowed at its base by a circular groove, in which is lodged the matrix of the claw. The small sesamoid (or navicular bone) is absent, but is replaced by a prominence of the ungual phalanx. The auricularis and index are alike, and not so long as the annularis and medius, which are the same in length. The Pig has four complete digits articulating from the metacarpals ; the thumb is absent. The 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 articulation. In the OiT, Sheep, and Goat, each of the perfect digits comprises three phalanges and three sesamoids. The first 'phalanx fairly represents the moiety p. ^a of the phalanx in the Horse. It has no posterior *^* imprints, but shows them on its inner surface for the attachment of several ligaments. This internal face is plane, and the external convex ; these characters are repeated in the other two m^^^^ ^^^*J """""iniini ^ phalanges. It is also remarked in all the pha- ' '. langeal bones, that the external articular facet of the extremities is always larger than the internal. Of the two sesamoids, the external is larger and less elongated than the internal, first particulate witri each other, and with the They halanx by small diarthrodial facets. The second phalanx is hollowed internally by a small medullary cavity. The ungual phalanx^ as a whole, resem!51es one of the lateral moieties of the os pedis of solipeds. This phalanx has no complementary fibro-cartilage, basilar process, or retrossal emi- nence, nor yet a cavity of insertion on the sides of the pyramidal eminence. The semilunar crest is replaced by an obtuse, thick, and rugged relief, which occupies quite the posterior limit of the inferior face of the bone. Three large '"T canals penetrate the third phalanx, two to the human scapula ; external aspect. baseof the pyramidal eminence,andonetowards ^ Supraspinous fossa; 2, Infraspinous the origin of the preplantar fissure. Theyform, ^ ^^J ^ g j^^, ^^^^ 4, Supra- m the mterior of the bone, a vast smus, giving .eapular notch ; 5, Anterior or axillary rise to several vascular canals which open on the ^J^^^, g jj^;^ \^ the scapular and surface. There is only one foramen at the base of o-ienoid cavitv • 7 Inferior angle • 8 the pyramidal eminenceinthemaZZer i^i^mman^s. ^^^^ ^^ the scapula; 9, Posterior border; 10, Spine; 11, Triangular COMPARISON OF THE THORACIC LIMB OF MAN WITH smooth surface. Over which the tendon THAT OP THE DOMESTICATED ANIMALS. of the trapezius glides, with the tubeiv A. Shoulder.— The shoulder of man (fig. 54) culum spinaj scapulae between it and has for its base two well-developed bones, the 10; 12^ Acromion process; 13,.Nutrient scapula and clavicle. The scapula is more dis- foramen , 14, Coracoid process, tinctly triangular than that of all the domesti- cated animals; 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 scapulo- humeral articulation. The latter is separated from the remainder of the spine by a constriction called the pedicle of the acromion. The coracoid process is voluminous, and resembles a st mi-flexed finger. 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. B. Arm. — The humerus of Man is much longer than that of animals. Its diaphysis is prismatic and divisible into three faces; the deltoid imprint has the form of a V with its point directed downwards. '^r'K.v ,r«i«*v.i«r.«c. o^fi^nio,. y,t^aA i^, fnyno/i inwards* thA Fig. 55. The voluminous articular head is turned inwards ; the Fig. 56. HUMAN AEM-BONES; FRONT VIEW. 1, Shaft of ulna ; 2, Greater sigmoid notch; 3, Lesser sigmoid notch; 4 Ole- cranon process ; 5, Coronoid process ; 6, Nutrient foramen; 7, Ridges for inser- tion of interosseous membrane; 8, Capi- talum ulnae; 9, Styloid process; 10, Shaft of radius; 11, Its head; 12, Its neck ; 13, Its tuberosity ; 14, Oblique Ime; 15, Lower end of bone; 16, Styloid process. 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 msertion of deltoid ; 10, Nutrient foramen; ^, 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. bicipital groove is single, and looks outwards. The inferior articular surface resembles that of animals, except that the condyle is more distinct. C. Fore-arm. — ^The two bones of the fore-arm, as we have already seen, only articu- late by their extremities ; they are separated from one another in their middle part. The superior extremity of the radius corresponds to the condyle of the humerus ; 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 cor- responds to the greater portion of the carpus, while the ulna only articulates with the pyramidalis ; 2, That the radio-carpal articulation is protected outwardly and inwardly by two small osseous prolongations, the styloid processes of the ulna and radius. D, Hand. — 1. Carpus. — The carpus of Man is composed of eight bones — four in each THE POSTEBTOB LIMBS 91 Fig. 57. row. The three first of the upper row articulate with the radius ; the fourth responds to the 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 finger. The pisiform bone and the cuneiform process of the unciform convert the posterior face of the carpus into a channel. 2. Metacarpus. — The five metacarpals of Man are parallel to each other, and articulate by their superior extremities with the bones of the car- pus ; by their inferior extremities with the phalanges. They are all concave in their middle portion, and thickened at their ends. The metacarpal of the thumb is the shortest and strongest. The others diminish In volume from the fourth to tiie first. 3. Digital Begion. — Here we find five digits, eaoh composed of three bony columnettes, witli the exception of the thumb, in which only the second and third pha- langes are present. They decrease in length from the third to tlie first, and the third to the fiftli. , The first and second phalanges are small semicylindrical bones, slightly thickened at their extremities. The ungueal phalanges are constricted in their middle, and widened like a horse-shoe at their inferior extremity ; the palmar face is roughened, the dorsal face smooth. Article V. — ^Posterior Limbs. Eacli of these is divided, as already noted, into four secondary regions : the jpelvis, thigh, leg, emd/ooL PELVIS. PALMAR SURFACE OF LEFT HUMAN HAND. The pelvis is a kind of bony cavity formed by the union of the sacrum with two lateral ^ ^ , avMAN hand. V ., 1 • 1 Tj J. J •ax. 1, ocaphoid bone; 2, Semimnare ; pieces, the COXSB, which are consolidated with '3^ Cuneiform ; 4, Pisiform ; 5, each other in the inferior median line. The ~ " description of the sacrum having been already given, it now remains to speak of the coxa. Trapezium ; 6, Groove in tra- pezium for tendon of flexor carpi radialis,* 7, Trapezoides; 8, Magnum ; 9, Unciform ; 10, 10, The five metacarpal bones ; 11, 11, First row of phalanges; 12, 12, Second row; ]3, 13, Third row,- 14, First phalanx of the thumb ; 15, Second and last phalanx. A, Coxa, The coxa, also designated os iliacum, os inno" minatum, is a very irregularly-shaped flat bone, double (with its fellow on the opposite side), 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 is inflected inwards to be united, on the median line, with the bone of the opposite side. It is divided, in the foetus, into three distinct pieces, joined by cai-tilage in the centre of the cotyloid cavity, which the three concur in forming. Although they soon become consolidated into a single piece, it is customary to describe them as so many separate bones by the names of ilium, pubis, and ischium. Ilium. — 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 avgles. 92 TEE BONES. Faces, — The external or superior face, studded with some imiscular imprints, is excavated on both sides, and is named the external iliac 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 iliac 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; Borders* — The anterior border, or crest of tJie ilium, is slightly concave. Fig. 58. THE COX^; 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, llio-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,-^ ^. he 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 C 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-feinoral muscle.) THE P08TERI0B 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 ; 3, 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 ilio-pectinea) that insensibly subsides above on the inner face of the ilium, and is continued 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. Pubis. — 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 crest j 4, Cotyloid cavity ; 5, Symphysis pubis j 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. 94 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 with the antero-internal angle of the ischium, to inclose, inwardly, the oval foramen. Ischium. — 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 quadrilateral 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 pelvic cavity. It has a small nutritious foramen directed out- wards. The inferior presents some rugosities clustered particularly about the symphysis. Fig. 60. 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 ex- 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 pelvic 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. ThQ postero-internal angle THE FOSTEBIOE 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. The Coxa in General.— 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) fijramen, 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 coxae, by uniting in their posterior part, form the articulation to which has been given the name of iscMo-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. Structure and Development of 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 efforts communicated to the trunk by the posterior limbs. It is also in this cavity that ossification commences. B. The Pelvis in General. 1. External and Internal Conformation of the Pelvis. — 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 coccygeal vertebrae ; 2, On each side the sacral grooves, at the bottom of which open the supersacraJ canals. 96 TBJE BONES* The inferior region is nearly horizontal. Formed by the pubes and ischia, it presents from before to behind : 1, In the middle, the ischio-pubic symphysis; 2, On each side the subpubic 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 lateral 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 deep 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 Bi inches. The second is measured from one pectineal crest or eminence to another ; the mean of this is 8y^^ 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 S^^ 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-^^ 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 TEE POSTEBIOB LIMBS. 97 disposed as a smootli 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. Differences in the Pelvis of the Sexes. — The pelvis of the Mare exceeds that of the Horse in all its dimensions, but the difference is most marked in the transverse 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 crests 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 tuberosities 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. Horizontal Diameters. Between the Pectineal Crests. Between the Supercoty- loid Crests. HORSE. Horizontal Diameters. Between the Pectineal Between the Supercoty- Crests. loid Crests. Inches. 9i Inches. *5 Inches. Inches. MARE. Vertical Diameters. Between the Sacrum and Between the Sacrum and Pubis. Ischium. HORSE. Vertical Diameters. Between the Sacrum and Pubis. Between the Sacrum and Ischium. Inches. Inches. Inches. 8 Inches. 6^5 98 THE BONES. To recapitulate, there is observed in the pelvis of the Mare: 1. A great increase in the transverse diameters; 2. A deep and regularly concave ischiatic notch; 3. A wide and concave ischial arch ; 4. Circular obturator foramina; 5. The cotyloid cavities distant from the pubic symphysis. 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 hody and two extremities. Body. — It is irregularly cylindrical, and presents for study /owr /aces. 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 above 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 suhtrochanterian crest^ because of its position under the trochanter ; below, a deep fossa, named the suhcondyloid, 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 convexity, incrusted witli 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 Cuyier, and takes the plaoe of the extf^^rnal and Biiperior branch of the linea aspera of Man. (It is the external small trochanter of Percivall and the middle trochanter of Leyh.) THE POSTERIOR LIMBS. 99 inserted, after gliding over the convexity ; 3, Posteriorly, tlie 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 Yig;. 61. Fig. 62. LEFT FEMUR i 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, Tuberosities for tendinous and ligamentous insertion ; 9, Trochlea. LEFT FEMUR; POSTERIOR VIEW. 1, Head ; 2, Great trochanter ; 3, Third, or trochanter minor externus 5 4, Lesser, or internal trochanter : 5, Fossa for insertion of ligamentum teres; 6, Trochanterian fossa ; 7, 8, Tuberosities ; 9, Fossa for the insertion of the external meniscus^ 10, Supracondyloid fossa; 11, Condyles. by the presence of tioo condyles and a trochlea. The two condyles, placed one beside, the other behind, correspond to the superior extremity of the tibia. They are separated by a deep depression designated the inter condyloid 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 100 THE BONES. Fiv. 63. 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 interees^yloid notch, by a large tubercle of insertion. The trochlea, 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 the trochanter, and the last for the inferior extremity alone. LEG. This has for its base three bones : the tibia, peroneus (ov fibula), and the rotula (ov patella) o 1. Tibia. The tibia is a long, prismatic bone, thicker at the superior than the opposite extremity, and situated between the femur and the astragalus, in an oblique direction downwards and backwards, constituting the principal portion of the leg. Body. — This offers for study three faces and three borders. The faces are wider above than below. The external is almost smooth, and is 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 triangular 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 ati-achment 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, external, 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 firsts the smallest^ is a rugged process continuous with the tibial crest, and separated from the external tuberosity by a wide and SECTION OF LEFT FEMUR, SHOWING ITS STRUCTURE. TEE POSTERIOR LIMBS. 101 Fig. 64. 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 tuberosity, 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 excavated 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. I'he external tuberosity ^ projects but little, and is traversed in its middle by a vertical fissure. The internal tuberosity,^ better defined, is margined posteriorly by an oblique channel. Structure and development, ^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 extifcmity 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 Peroneus), A small, undeveloped bone, elongated and sty- loid 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- drical, and forms above, in common with the external border of the larger ^ The external malleolus of Man. 2 r^j^g internal malleolus. 10 POSTERIOR VIEW OF RIGHT TIBIA. 1, Tibial spine; 2, 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 trochlese with a median ridge, for articulation with the astragalus. 102 THE BONES. bone, the tibial arcb. Its sujperior 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. Fatella. 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. The su])erior row only comprises two bones, the largest ; these are the astragalus and the calcaneus (or calcis). The inferior row is formed, out- wardly, by the cuboides alone ; inwardly and anteriorly, it is subdivided int ) two secondary rows, the superior of which is constituted bv 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 TEE P08TERT0B LIMBS. 103 calcaneus, between the tibia and the scaphoid, and divided mio Jive faces : — 1, A superior and 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 j 8, Small metatarsal bone; 9, Suf- supenor 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 two faces, two borders, and two extremities. The external face 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 calcaneus, 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- fraginis, proximal, or first phalanx ; ___„. i^^oST".: %^rril: loped fro-f two-nucleTof ossification^ one of Pedal bone, or third or distal whlch IS for the summit.^ phalanx ; 14, Navicular bone ; 15, Cuhoid bone. — This little bone, situated Basilar process of pedal bone. ^fc the external side of the scaphoid and the 104 THE BONES. large cuneiform bone, between the calcaneus and two of tbe 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 hone (the large cuneiform of Percivall). — Flattened above and below, it is described as having two faces and a circumference. The faces, both articular, are furrowed by a channel of insertion, and are distinguished 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 hone (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 horder is provided with one or two facets to correspond with the cuboid bone ; and its internal horder also offers one, which is in contact with another on the small cuneiform. Its anterior horder 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, scaphoid, num ; 5, Cuboides. or cuneiform medium ; 4, Cuneiform mag- num ; 5, Cuboides ; 6, Cuneiform parvum. Sm^U Cuneiform hone, — 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, and one internal. When this bone is in two portions, there are then three cuneiforms, which may be distinguished, as in Man, by naming them^rs^, second, and third. THE FOSTERIOB LIMBS, 105 Fig. 68. 2. Bones of the Metatarsus. These bones are tliree in number, a median and two lateral, and offer the greatest analogy to tbe metacarpal bones. This enables us to dispense with a general description of them, and to confine ourselves only to indicating the differential characters which distinguish them from the corresponding bones in the anterior limb. The principal, or median metatarsal bone, is longer than the same metacarpal, and its body, instead of being slightly compressed before and behind, is nearly a regular cylinder. It presents out- wardly a fissure which is directed at first obliquely 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 hones, 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 Begion. 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 contrary, wider and thicker at its superior extremity ; 2, That the 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 posterior aspect of sesamoids are less voluminous; 5, That the navicular i^^ft metatarsus. bone is shorter and narrower. 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. DIFFERENTIAL CHARACTERS OP THE POSTERIOR LIMB IN OTHER THAn'sOLIPED ANIMALS. A. Pelvis. — It is remarked : 1, That in all the domesticated animals, with the exception of Solipeds, the direction of the coxae is nearly horizontal ; 2, That in all, 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 Ox, Sheep, and Goat, the space between the two coxsg is scarcely so great in front as behind ; the ilium is not volumi- nous, and has only three processes on the superexternal iliac spine. There is no furrow on the lower face of the pubis, and its upper face, like that of the ischium, is very concave. Three eminences are seen on the postero-external angle of the ischium. In early life, tiie ischio-puhic symphysis shows an epiphysary nucleus in the middle of its inferior face. (The epiphysis on the inner border of the ischium has been considered by some anatomists as an inde- pendent bone, and described by them as the interischial hone.) 106 THE BONES. The rim of the cotyloid cavity has also three notclies, and the supracotyloid crest, or ischiatic spine, is very elevated and sharp, and but little roughened outwardly. The external 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 of the ilium is convex, and there is no protuberance outside the ischio-pubic symphysis. In Carnivora the lateral diameter of the pelvis is greater behind than in front. Tiie 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. Thigh. — In all the domesticated animals except Solipeds, the femur tends to become curved, prismatic, and triangular 5 the posterior 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 obli(iue osseous lip ; the latter trochanter subsides and forms a single mass whose summit and convexity are con- founded ; the third trochanter, the fossa, an J the supracondyloid crest are more or less effaced. In the Ox, there is no subtrochanterian crest ; the supracondyloid fossa is shallow, and the crcbt little noticeable. The head is well detached and i as its centre ex- cavated by a shallow fossa of insertion. The trochlea 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 the posterior face are replaced by some salient lines; the trochanter is on a level with the head ; the latter is supported by a somewhat constiicted 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 depth of the digital fossa, which is bordered by an oblique lip extending from the great to the small trociianter. 0. Leg. — 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 also 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. The 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 ; 3, 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 interosseous ligament. It is developed from three ossific 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 TEE POSTERIOR LIMBS. 107 fibula is also as long as the tibia, and is united to that bone at three points : at the two extremities by articular surfaces, in the inferior third and middle by an interosseous ligament. D. Posterior Foot. — 1. Bones of the tarsus. — The number of tarsal bones varies a little in the domesticated animals, as the following list will show : Carnivora and Pig ,<..., 7 Ox, Sheep, and Goat » 5 In the Dog, Cat, and Pig, there are tliree cuneiform bones, and in the Ox and Sheep, in addition to there being only two cuneiforms, the scaphoid and cuboid bones are « on- solidated into one piece. The astragalus of the earnivora articulates with the scaphoid by means of a veritable head, separated from the rest of the bone by a constriction termed the ntck of the astra- galus. The cuboid and the cuneiform bones respond to all the metatarsals. In the Pig, the astragalus and calcaneus are very long. The cuneiforms and cuboid respond to the four perfect digits. The tarsus of the domesticated Buminants is slender above. The astragalus is el ongated from above to below, and is united to the scaphoid by an antero-posterior groove, and to the calcaneus by a more superficial vertical groove. The calcaneus is long and t/in; the posterior gliding surface on the summit is excavated into a channel; the small cuneiform is pisiform and but slightly developed. 2. Bones of the metatarsus. — The metatarsus is also a region in which the number of bones varies in the domesticated animals. Thus in the Carnivora and Pig there are five, and only two in Ruminants. The metatarsals of the Carnivora and Pig are exactly like the same bones in the anterior limb. Those of Buminants are slightly diiferent. In the Dog and Cat are one rudimentary and four perfect metatarsals. The former is articulated with the internal cuneiform, and represents the vestige of the thumb. The Pig has four perfect metatarsals, and an internal rudimentary one. The latter is a small bone flattened on both sides, articulating by means of a diarthrodial facet, and sometimes consolidated behind the upper end of the fourth metatarsal. In the Ox, Sheep, and Goat, is found a principal and a rudimentary metatarsal bone. The latter is like the rudimentary metacarpal bone, but the former differs from the principal metacarpal bone in being longer, quadrilateral in form, and having a vascular canal traversing the posterior face of its upper extremity. 3. 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 the rudimentary metatarsal bone alluded to above. Nevertheless, it frequently occurs that a completely developed thumb is found in this animal ; and in this case the rudi- mentary metatarsal is ordinarily followed by a ligamentous cord, to which is suspend( d a bony stylet that represents either the inferior extremity of the metatarsal, or the first phalanx ; it is to this stylet that are found articulated in succession the second and third phalanges. (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 OP THE ABDOMINAL LIMB OF MAN WITH THAT OP ANIMALS. A. Pelvis. — The longitudinal axis of the pelvis of Man forms, with the horizon, an angle of about 40°. The bones which compose it are proportionately larger and stronger t! an 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 sympliysis% and ihe con- cavity which, in the domesticated animals:, is called the ischial arch, id designated in Man the pubic arch. Ill consequence of the excavation on the inner face of the ilium, the pelvic cavity may be divided into the great and lesser pelvis In the latter are lodged the genital and urinary organs, as well as the extremity (f the d'gettive tube. B. Thigh. — The. femur of Man is nearly vertical, and situated in a direction slightly lOS 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 this prism forms a somewhat salient crest, which takes the place of all the insertion eminences on the pos- terior aspect of the femur in animals, and is designated the linea aspera. This line bifurcates above and below ; below, the branches margin a triangular or po;pliteal space. Fig, 69. 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 fossae ; 7, Antero- superior spinous process; 8, Antero-inferior spinous process; 9, Acetabulum. — a, Its notch ; 6, Body of ischium ; c, Its tuberosity ; d, Its spine ; e, Pubis ; /, Symphysis pubis ; g. Arch of the pubes ; A, Angle of os pubis ; «, Spine of pubes, with crest between it and A ; k, k^ Pectineal line ; I, I, Ilio-pectineal line, with its prolongation, m, m; w, Ilio-pectineal eminence; o, 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. The two condyles are joined together in front by the trochlea, which is wide and shallow. C. Leg. — 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 italic S. On the inner aspect of the inferior extrendty is seen a voluminous process which occupies, inwardly, a portion of the tibio tarsal articulation: this is the internal malleolus. The articular surface is not exactly formed to correspond with the whole articular surface of the astragalus. The Jilmla is as long as the tibia. It is prismatic, and slightly twisted on itself. It articulates above and below with the tibia. 'J'he lower extremity responds to the astra- galus, and forms a prominence named the external malleolus. There is nothing particular to note in the patella. D. Foot. — The /oof 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 taxsus 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 cuneiform 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 volundnous. THE tlMBB IN GENEBAL. 109 8. Digital reg/ow.— This comprises five digits or toes. The phalanges of these toes are analogous to those of ttie fingers, from which they are distinguished by their small size. They increase in volume from the first to the fifth digits Fig. 70. Fig. Ih Fig. 72. EIGHT HUMAN FEMUR*, ANTERIOR ASPECT. 1, Shaft; 2, Head; 3, Neck ; 4, Great tro- chanter ; 5, Anterior 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. HUMAN TIBI^ AND FIB- ULA OP RIGHT LEG; ANTERIOR ASPECT. 1, Shaft of tibia ; 2, Inner 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. DORSAL SURFACE OF LEFT HUMAN FOOT. 1, Astragalus; 2, Its An- terior extremity articu- 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. Article YI. — The Limbs in General and their Parallelism. A. The Limbs in General. — 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 to a difference between the anterior and posterior members. The front limbs^ IJO 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 through the muscles that attach that bone to the trunk. It then passes to the 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 io 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 ^x 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 (See 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 Limbs. — 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 Yicq-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. Ill meditations. In sucli 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. Yicq-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. Wo 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 di£&culty 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 fossaB. 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 glenoid cavity of the scapula. There remains to determine in the latter bone 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 position. Parallel "between the femur and humerus, — The resemblance between these two bones is remarkable. Thus 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 ; 3, 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 indicated. 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 humerus. Parallel heticeen the bones of the leg and those of the fore-arm, — It is 112 TEE BONES, more particularly in these two regions that the question of analogies has been resolved in a contradictory manner by anatomists. It would have appeared less complicated had it been studied in a large number of species. 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. It is true 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 hones 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 to compare, 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. CHAPTEE III. THE BONES IN BIKDS. These animals, destined for the most pai-t to sustain themselves in the air, should exhibit in the conformation of their skeleton all the conditions which may favour aerial locomotion; from this arise the differences which distinguish their -skeleton from that of mammalia, — differences which will now be rapidly traced. Vertebral Coltjmn. — Cervical vertebrse. — The cervical stalk represents in the bird, as in the mammal, a kind of balancing pole curved like an S, 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 forwards. But when it rests on the ground, it makes the balancing-pole assume the natural and more or less giaceful inflection, by throwing the head backwards, and transfei-ring 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 vertebrae composing it number fourteen in fowls, twelve in the pigeon, fifteen in the duck, and eighteen in the goose / in the swan twenty-three have been counted :— a curious variety wliich singularly contrasts with the numerical unity noticed as one of the most remarkable characters in mammalia! These vertebrsB are generally longer than in the latter class, and are particularly distinguished by the configuration of the TEE BONES IN BIBDS. 113 articular etirfaces 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 TOWL, From A to B, Cervical Vertebrae.r^l, Spinous process of the third vertebra ; 2, Inferior ridge on body of the same ; 3, Styloid prolongation of the transverse process of 114 TBE BONES. reciprocal clamping. In this manner, the anterior head of the body of each vertebra is replaced by a facet concave from one side to the other, and convex vertically ; while the posterior extremity of the bone bears, instead of a concavity, a facet convex in the lateral sense, and concave from above to below. The inferior crest of the body (fig. 73, 2, 2) only exists in the first and last vertebrse , but it forms a veritable spine, analogous to that observed in the lumbar vertebrae of the rabbit. The spinous process (fig. 73, 1, 1') only forms a simple crest in the middle part of the neck , it becomes more salient in the vertebrse which occupy the two extremities of this region. The transverse process represents on the side of the vertebra a tiiick, obtuse, and irregular tubercle, situated under the anterior articular process, and pierced at its base by a large vertebral foramen (tig. 73, 4, 4'). It is most frequently furnished with a small styloid prolongation, (fig. 73, 3, 3') directed backwards and downwards, forming an epiphysis at an early period, and representing a real undeveloped rib. 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 &mgle condyle of the occipital bone. Tiie axis shows a very marked odontoid process with a single facet under that eminence. Dorsal vertebrse (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 efibrts that flight demand:}. 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 vertebrse. Tne spinous processes, flat, wide, short, and consolidated with each other by their opposite borders, constitute a long crest extending fiom the last cervical vertebra to the bones of the wings (fig. 73, 7). Tne transverse processes widen to their summit ; in the fowl they are nearly constantly fused with each other. Lumhar and sacral vertebrse.— All these vertebrse 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 vertebrse, 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 transversa processes. The former are closely united to the latter in the dorsal region. Coccygeal vertehrx. — In the coccygeal 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 vertebrse which serve as a base for the steering feathers should preserve their independence, so as to allow these to be carried to the right, left, downwards, or upwards. These vertebrse, seven in number, present spinous processes which are often bifurcated, transverse processes very developed, and sometimes even spines more or Jess 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 point. Head (Fig. 73, p. 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 c, Dorsal Vertebrae. — 6, Spinob process of the first ; 7, Crest formed by the union of the other spinous processes.— From d to E, Coccy- geal Vertebrae. — f, g, Head. — 8, Interorbital septum ; 9, Foi*amen of communica- tion between the two orbits; 10, Premaxillary bone ; 10', External openings of the nose; 11, Maxilla; 12, Square bone; 13, Jugal bone. — H, Sternum. — 14, Brisket or keel; 15, Episternal process; 16, Internal lateral process; 17, Lateral external process; 18, Membrane >vhich closes the internal notch; 19, Membrane of the external notch. — i, etc., Superior ribs. — 20, Posterior process of the fifth. — J, Inferior ribs ; K, Scapula ; L, Coracoid bone; if, Furculum. — w, m, Its two branches. — N, Humerus ; O, Ulna. — o, Radius. — P, p y Bones of carpus ; Q, q'. Bones of metacarpus; R, First phalanx of the large digit of the wing.— r, Second phalanx of the same. — r', Phalanx of 'thumb; s, liium; s'. Ischium; s", Pubis. — 21, Sciatic foramen; 22, Foramen ovale.— T, Femur; u, Patella; V, Tibia ; x. Fibula. — ?/, Single bone of tarsus. — Y, Metatarsus.— 23, Superior process representing a united metatarsal bone ; 24, Process supporting the claw. — z, etc., Digits. TEE BONES IN BIBD8. 115 Bones of the cranium. — The bones which compose the cranium are, a8 in mammalia, an occipital, parietal, frontal, ethmoid, sphenoid, and two temporals. These bones are net isolated from each other, excepting during early life in the shell, and the ossifying process which unites them is so rapid, that the cranium, shortly after hatching, is already a single piece. No detailed description of the separate bones will be given here, but 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 foramen, 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 penetrate the cranium, and represent permanent fontanella. The parietal bone is feebly developed, and formed from only two primary nuclei. The frontal is the largest bone of the cranium; its orbital process is supported by 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 forms between the two orbits a thin vertical septum (fig. 73, 8). Its posterior border is notched opposite 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 at its extremities, one entering the cranium, the other the nasal cavities. This fissure and these foramina permit the passage of the ethmoidal nerve, which in this way traverses the orbit b«ore arriving at its destination. The ethmoidal cells are more membranous than bony ; iheir base is attached to a very delicate transverse plate, which is often membranous and* not cribbled, and forms part of the anterior orbital wall. These cells repla -e, at the same time, the lateral masses of the ethmoid and turbinated bones of mammalia. The sphenoid appears to be formed of a single piece, and shows on its sides two diarthrodial facets corresponding to the pterygoids. 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 notch of the interorbital septum, and thus allows each of the nerves passing through it to reach the eye for which it was intended. It is worthy of remark, that an analogous disposition is also noticed in the rabbit.* The temporal bones present at their base an articular surface corresponding to the square bone. In the fowl species, the zygomatic process forms a small flattened tongue, directed 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 consolidated and confounded so intimately, that it becomes impossible to distinguish them from one another. From this union results a long and strong process, which inclines ibrward and meets a particular prolongation of the OS unguis, forming with it areal bony arch. This arch limits, below and outwardly, the orbital cavity. Bones of the face. — The supermaxilla c mprises; a premaxilla, two nasal, two lachrymal, two palate, two pterygoid, 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 hones. The premaxiUary hone is found, before hatching is completed, of two lateral pieces, which represent the two small premaxillaries of mammals. This bone is very considerable, and of itself forms the base of the upper beak, whose form it determines ; it is pointed and conical in the gallinacea, and wide and flattened above and below in palmipedes. In front it circumscribes the external openings of the nose, and is prolonged superiorly into two lengthy processes which dovetail between the nasal bones. Two inferior processes belonging also to this bone concur in the formation of the palatine roof. The supermaxillaries^ analogues 9f the supermaxillaries of mammals, are two rudimentary bones situated on the sides and at the base of the beak. They form a part of the palatine roof and the walls of the nasal cavities. The nasal hones ciicumscribe 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 part the roof of the palate ; their pt)sterior extremity lies against the pterygoids ; the anterior joins the supermaxillaries and the inferior process of the premaxiUary bone. The pterygoids extend obl-quely from the sphenoid to the square bones, and are united to the sphenoid by diarthrodial articulation. * This analogy is really striking, and might, in our opinion, serve as a basis for a 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. Tills manner of viewing it tends to confirm the ideas of M. Tabourin on the inferior sphenoid and the ethmoid of mammals. 116 THE BONES, The zygomatic hones have the form of two very thin stylets, and are united to the square bone by their posterior, and consolidated with the supermaxillary by their anterior extremity. The vomer separates the guttural opening? of the nose from one another. 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. This arrangement allows the upper beak to execute a certain elevating movement, of which we will speak when describing the articulations. The inferior maxillary hone is originally formed of a great number of distinct seg- ments which are soon united into a solid piece. The square, petrous, or hone of the tympanum ought to be considered as detaclied from tiie temporal. It is prismatic in shape, and provided on its upper sui-face with a diarthrodial facet which unites it to the temporal, and on its lower face with another facet articulating with the branch of the maxilla. Outwards it joins the zygomatic bone, and inwards with the pterygoid. 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 process. Thorax. — Sternum (fig. 73, h). — The sternum of birds, serving as a basis of support to the muscles moving the wings, should offer, and does in fact show, a remarkable degree 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 wing. For this reason we may Infallibly pronounce as to the extent and power of a bird's flight 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 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 '* ncave, while the inferior is convex, and entirely occupied by the insertion of the pect( Sis borne in mind what profound modifications the vertebrae must have ex- perienced to constitute the bones of the head At present the problem appears solved. The head is composed of four vertebrsB, in which are found the various parts enumerated in the description of the typical vertebra. TEE VERTEBRAL CONSTITUTION OF THE SKELETON. 121 In tlie four classes of vertebrata, the head is constantly formed of four vertebree, which are determined as follows :" * VERTEBRJi:. CENTRUM. NEURAL ARCH, H.EMAL ARCH. Occipito-hy oidea 1. Basilar process of the Occipi- tal. Occipital (3 pieces). Mastoid walls of the I Tympanum. Hyoideal appa- ratus (5 pieces). I Parieto-maxillary. Body of the pos- | Wing and pterygoid teiior Sphe- I process of the pos noid. I terior Sphenoid. Squamous portion and ] zygomatic process of I the Temporal. : Parietal. Inferior Maxilla 5 pieces). Fronto-mandibular. Body of the Anterior Sphe- noid. "Wing and pterygoid process of the anterior Sphenoid. Posterior Frontal and its orbital process. Frontal. Jugal. Lachrymal, Palatine. Supeririaxillary. Premaxiilary. Naso-turbinal. Vomer, Ethmoid. Nasal. I Turbinated I Subetlimoidal. The number of cephalic vertebraB is invariable, as each is destined to lodge the organs of one of the four senses. The occipito-hyoideal lodges the principal organs of hearing; the parieto-maxillary osteodesm protects the sense of taste ; finally, the organs of vision are sustained by the fronto-man- dibular vertebra, while the naso-turbinal contains the sense of smell. It was therefore with reason that Geoffroy Saint-Hilaire and Professor Owen proclaimed that the type of construction of the vertebrated animals is the vertebra. SECOND SECTION. The Articulations. CHAPTEE I. THE ARTICULATIONS IN GENERAL. The different pieces constituting the solid framework of the animal body are, as has been said, united in such a manner that they can move one upon the otherr From this union results the articulations or articular joints, whose construction will now be referred to in a general manner, before commencing a particular description of each To form articulations, the bones correspond to each other by certain points of their periphery, which are named articular surfaces. Every articu- * Lavocat^ * Nouvelles etudes sur le systeme vertebral,* 1860. 122 TEE ARTICULATIONS, lation IS, therefore, essentially constituted by two opposite osseous surfaces, which are moulded to each other. These are either contiguous, independent, and very movable — continuous with each other by means of a cartilaginous substance which condemns them, if not to total immobility, at least to very PLANS OP THE DIFFERENT GLASSES OP ARTICULATIONS. A, Suture. — 1, Periosteum; 2, 'Sutural ligament. — B, Amphiarthrosis ; a, First degree. — 1, Periosteum ; 2, Articular cartilage ; 3, Interarticular ligament. — 6, Second degree ; 4, Single cavity in the interarticular ligament. — c, Third degree ; 6, Double cavity m the interarticular ligament, — c, Diarthrosis ; 6, Simple diarthrosis. — 1, Periosteum; 2, Articular cartilage; 3, Epithelial layer of the synovial membrane — dotted line ; 4, Fibrous capsule ; 5, Cul-de-sac of the syno- vial membrane ; 6, Fibrous layer of the synovial membrane. — c, Double diarthrosis ; 7, Interarticular meniscus ; 8, 9, Cavities of the two synovial membranes. limited movements : or united by a fibro-cartilage whose elasticity permits a certain degree of displacement between the bones which are in contact. In the first case, the articulations are classed as diarthroses, or movable articulations. In the second, they are designated synarthroses, sutures, or immovable articulations. THE ABTICULATI0N8 IN GENERAL. 123 In the third, they are amphiarthroses, or mixed articulations ; so termed because they participate in the movements of the other two classes ; synar- throses, by the continuity established between the articular surfaces ; and diarthroses, by the extensive motion they permit. The general characters that distinguish each of these three great classes of articulations will be successively studied. (The study of the articulations, or rather of the ligaments, is termed syndesmology — from crvv, together, and 8ecr/xo9, bond; or arthrology — from apOpov, a joint, and Xdyos, a description.) GENERAL CHARACTERS OF DIARTHROSES. We ought to consider in the diarthrodial articulations : 1, The con- tiguous hony surfaces which form them ; 2, The cartilaginous layer (cartilages of incrustation) which cover these ; 3, The fibro-cartilaginous tissue (articular fihro- cartilages) which complete them, when they are not shaped so as to be reciprocally adapted to each other ; 4, The ligaments which maintain tbem in contact ; 5, The serous membranes (^synovial capsules) that cover the internal face of the latter, and which secrete the synovia, a kind of animal oil that facilitates the gliding of the articular surfaces ; 6, The movements of which these articulations may be the seat ; 7, Their metJiodical classifica- tion ; 8, Their nomenclature. Articular Surfaces. — These surfaces have the common character of being destitute of asperities, so that they can glide with the greatest facility on each other. They are designated, according to their form, by the names of facets, heads, condyles, cotyles, glenes, pulleys, etc. There is no need to revert to their general description, as they have already been sufficiently studied in the osteology; so we will confine ourselves to repeating that they are found at the extremities of long bones, on the faces of short bones, and on the angles of wide bones. We may mention also that they are often excavated by one or several hollows named synovial fossce, a sort of natural reservoirs which receive the unctuous fluid secreted by the interarticular serous membranes : Cartilages of Incrustation. — This designation is given to the layers of cartilaginous matter which, as it were, varnish the articular surfaces they adhere to by their inner face ; their free surface is distinguished by a remarkable polish and brilliancy Thicker towards the centre than at the circumference when they cover bony eminences, these cartilages show an inverse disposition when they line cavities They are elastic, of a pearly whiteness, and resisting, though they are soft enough to be cut by a sharp instrument ; in a word, they possess all the physical characteristics of the primary cartilage of bones They appear to be formed of parallel fibres placed perpendicular to the bony surfaces, and implanted iu these by one of their extremities : the opposite extremity corresponding to the free surface of the cartilage. Viewed by the microscope, they are foimd to consist of a fundamental substance excavated by small cavities The cartilage of incrustation therefore belongs to the group of true or hyaline cartilages- The fundamental matter is amorphous and homogeneous, and more or less transparent, according to its thiclmess. It is transformed into chondrine by boiling in water. The cavities are irregular, and more or less wide. They contain from one to five cells whose walls are very thin, and their contents slightly gran^ ular; in the centre of each cell is a nucleus with a nucleolus. These 124 THE ARTICULATIONS. cavities are elongated and directed almost perpendicularly towards^ the articular surface in the deep layer ; in the middle layer they are oblique, and are parallel to the surface of friction in the superficial layer. (Under a high magnifying power ^^S- '^^- the fundamental substance, or matrix, loses its homogeneous and amorphous character, and appears to be granular or faintly striated. In the midst of this granular matrix, the lacunae or cavities are observed to contain from one to six different-sized cells. It has been stated that a membrane lines these spaces. In addition to the granular matter observed in the cells, it is not rare to find fat globules. The nuclei of the cells vary from ¥oV^ to ^0^ of an inch in diameter. The cells multiply endogenously.) The cartilage cells are insoluble in boiling water ; consequently, so far as their chemical composition is con- cerned, they are distinct from the fundamental substance. The diarthrodial cartilages receive neither vessels nor nerves. The presence of cartilages of incrustation in the articulations is of the greatest importance. When they are worn, absorbed, or transformed into bone in consequence of certain articular maladies, the movements become painful and very difficult. With regard to the part they play in the economy, it may be said that : 1, They favour, by their smoothness, the gliding and displace- ment of the bones ; 2, They attenuate, by their suppleness and elasticity, the violent shocks to which the articulations are exposed ; 3, They resist the wear and deformation of the articular surfaces. • Complementary Fibro-cartilages. — There are several kinds of com- plementary fibre -cartilages : — Some (interosseous) represent circular cushions which bolster the margins of certain cavities, filling up the notches which might render them imperfect. They increase the depth of these cavities Fig. 77. SECTION OF BRANCHIAL CARTILAGE OF TADPOLE. a, Group of four cells separating from each other ; 6, Pair of cells m apposition ; c, c, Nuclei of cartilage-cells ; d^ Cavity con- taining three cells. These cells are im- bedded in the finely-granular matrix, or fundamental substance. FiBRO-CARTiLAGE ; MAGNIFIED 155 TIMES. Showing interlacement of fibrous fasciculi, with scattered groups of cartilage-cells. and protect their borders from injury. Others (interarticulm) are inter- posed between articular surfaces when these do not exactly fit each other, as THE ARTICULATIONS IN GENERAL 125 when two opposing extremities are convex. It may be remembered that the lateral tuberosities of each tibial surface present, for articulation with the condyles of the femur, two convex diarthrodial faces whose coaptation is rendered perfect by the interposition between each condyle and correspond- ing tibial surface of a crescent-shaped fibro-cartilage, which for this reason has been named a meniscus. In other joints these interarticular fibro- cartilages are shaped like discs or biconcave lenses. There then result double diarthroses : — example, the temporo-maxillary articulation. (Fibro- cartilage also covers bony surfaces over which tendons play, as on the trochlear surface of the humerus, postero-inferior face of the navicular bone, and elsewhere. In these situations it is named stratiform fibro-cartilage.) These organs are formed, as their name indicates, by fibrous and car- tilaginous tissue ; their mode of association need not be referred to here, though it may be observed that the cartilage is more particularly found in all those points where there is most articular friction. They receive vessels, and sometimes nerves. Ligaments. — These are bands which unite contiguous diarthrodial surfaces. They are sometimes formed of white fibrous tissue, and some- times of yellow ; from whence their division into two great classes of white and yellow ligaments, a. The lohite ligaments are distinguished by the pearly whiteness of their tissue and want of elasticity. Those which are found on the outer ¥ig 7B ?ig 79. WHITE OR NON-ELASTIC FIBROUS TISSUE. YELLOW OR ELASTIC FIBROUS TISSUE, FROM 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 rihhon-shaped ; in the second, they are termed mem^ hraniform, 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, vessels, or nerves. The capsular ligaments are often complete — that is to say, they envelope the whole articulation like a sack. At other times they are incomplete, and 126 THE ABTICULATI0N8. 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. 5. The yellow ligaments are all jperi^lieral, 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 ground. Synovial. Capsules. — 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 uU 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 as a 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 ABTICULATIONS 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 pressure sustained by certain articulations, and the intense friction to which their 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 a physical law which no body escapes, let it be as hard as the diamond, or as soft 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 Cloptqn 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 fluid, 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 carriages. 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, w^hich 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 Classification of the Diaethroses. — 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. EnartTirosis, 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. 3. 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, fliough very diversely shaped, nevertheless exhibit in all the articulations one or more condyles opposed to an equal number of oval excavations. Example r 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. Kotation is the only movement. Example : the atlo-axoid articulation. 5. Arthrodia, or planiform diarthrosis, is constituted by plane, or nearly plane facets. Gliding is the only possible movement. Example : the carpo- metacarpal articulation. Nomenclature. — 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 Surfaces. — 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 laminae or trifling inequalities ; again, th^y 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. Modes of Union. — Cartilage interposed between these synarthrodia! 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 bringing 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 ABTIGULATIONS OF MAMMALIA IN P ARTICULAR. 129 animals by the elasticity they commuiiicate to the bony walls of the cranium or face. In the adult, they may be said to be null. Classification. — 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 parietal bone. 2. If the opposed borders of two bones in contact are widely bevelled, one inwards, the other outwards, it forms a scaly or squamous suture. Example : the parieto-temporal articulations. 3. When the union of bones takes place by plane or roughened surfaces, cirt perpendicularly on their borders or angles, this constitutes the harmonia suture, or suture hy 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. Articular Surfaces. — 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. Modes of Union. — The organs which perform this office are : 1, The fibro-cartilage which establishes continuity between the articular surfaces ; 2, Eibbon-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 movement, the extent of which depends on the thickness of the intermediate fibro-cartilage. Classification. — Only one kind of amphiarthrosis is recognised, the most remarkable example of which is found in the articulations between the bodies of the vertebrae. CHAPTEK II. ARTICULATIONS OF MAMMALIA IN PARTICULAR. In the special study of the articulations, the same order will be followed as 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 130 THE ABTICULAtlONS. are surrounded either by boiling, maceration, or scraping. 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 are prepared with 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. 2. It is convenient to separate the articulation we wish to dissect by sawing through the bo ties at a certain distance from the articular surfaces. The manipulation of the part is then rendered easier, and its dissection can be made under the most favourable conditions. 3. It is necessary to preserve as carefully as possible the muscles surrounding the articulations, in order to be able to study their relations with the ligaments which bind these. If it be absolutely necessary to remove them, their insertions corresponding to the articulation should always be retained. 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 turn, 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 very useful to inject their interior with plaster or tallow coloured black, in order to distend their cavities, and thus aid the study of their relations with ligaments, tendons, or muscles. For the preparation of each articulation it is not necessary to give 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 ligaments, I have thought it advisable to follow the example given in the last edition of ' Leyh's Anatomy ' by Zundel, and briefly indicate the readiest method of demonstrating these organs, for the special benefit of the student.) Article I. — 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 vertebrae to the ribs, in removing the supercostal and transverse spinal muscles. To expose the common superior longitudinal ligament, separate the bodies of the vertebrae 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 vertebrae, 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 vertebrae with each other ; the second those of the spine with the head, the ribs, and the c ^xae. Intervertebral Articulations. The vertebraB 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 TEE SFINE, 131 cervical vertebrae, all the dorsal and lumbar vertebrae, and the first sacral vertebra. Union of the Vertebra by their Bodies. — 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 cavity 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. Intervertehral fihro-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- cartilages, 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 vertebrae of the back concur to form the intervertebral cavities, v\ hich 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 fibro-cartilages as intervertehral ligaments. Luschka has shown that the cartilages are in reality articular capsules.) h. Common superior vertebral ligament (Fig 83, 1). — This ligament extends from the axis to the sacrum, and is lodged in the spinal canal ; it represents 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 vertebrae. 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 (vence hasium veriehrarium). c. Common inferior vertebral ligament {Fig. 84, 5).— Situated under the spine, this ligament is absent in the cervical aiid the anterior third of the dorsal region. It only really begins about the sixth or eighth vertebra of the latter region, and is prolonged 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 vertebrae 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 132 THE ARTICULATIONS. that it adheres to the crests on the bodies of the dorsal and lumbar vertebraB, 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 Vertebra by their Spinal 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 vertebrae themselves. They are covered by a thin layer of cartilage. 3fodes of union, — 1, A common superspinous ligament ; 2, Interspinous ligaments ; 3, Interlamellar ligaments ; 4, Ligamentous capsules, proper to the articular processes. a, Commoa 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 Ugament. These two ligaments, although continuous with one another, yet differ so strikingly in form and structure that they are best described separately. 1. SuperdorsO'lumhar 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 laminaB 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 vertebraB ; they are directed downwards or forwards, and reach the spinous processes of the last six cervical vertebrae, into which they are inserted by so many digitatipns, ARTICULATIONS OF THE SPINE. 133 Fior. 80. becoming confounded with the inter spinous 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 laminae 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 ligamenium nucJice, is all but absent in Man, being represented in him by a thin narrow band, or rather two thin planes of fibres, the ligamenta suhflava. 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. ) h. Intersjpinous ligaments (Fig. 80, 3). — Fibrous laminae fill the inter- spinous spaces, and are attached, before and behind, to tlie opposite borders of the spinous processes which they unite ; they are continued below by the interlamellar liga- ments, forming two lateral planes which are applied against each other, like the laminae 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 spinous processes. Their lateral surfaces are divided by a layer of grey elastic fibres, which cross like an X the direction of the preceding fasciculi. Very abundant in the anterior moiety of the dorsal region, these fibres operate, by their proper elasticity, in bringing the spinous pro- cesses towards each other. c. Interlamellar, or interannular ligaments. — Situated, as their name indicates, between the vertebral laminae, and divided into two lateral moieties, these ligaments appear to be produced by the two fibrous planes of 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 is 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 12 INTERVERTEBRAL ARTICULA- TIONS. A, B, c, Bodies of three dorsal vertebrae divided longitudi- nally and vertically to show (1, 1) a section of the in- tervertebral discs ; 2, Super- spinous dorso-lumbar liga- ment ; 3, Interspinous liga- ment ; 4, Fibrous fascia, con- stituting the proper capsule to the articular processes in the dorsal region. 134 THE ABTICULATIONS, to the articular processes. Yellow and elastic in the cervical region, these 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 Articulations. — 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 vertebrae they unite. The coccygeal bones only come in contact by their bodies, their spinal laminae 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-cartilages, 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 surfjice of the bones, which they envelope in a common sheath. 2. Intersacral articulations. — The sacral vertebrae 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 super spinous dorso- lumbar ligament is continued on the sacral spine, and that there exist be- tween the processes formed by this spine veritable inter spinous ligaments. 3. SacrO'lumhar articulation. — In this articulation, the great thickness of the fibre- cartilage is to be remarked ; and, in addition, that the last lumbar vertebra corresponds with the sacrum not only by its body and articular processeSy. 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. The bundles of fibres thrown from one bone to another from around these sacro- 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 vertebrae, — This is distinguished by the presence, between the transverse processes, of a planiform di arthrosis like that of the sacro- trans verbal 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 Articidations of the Head.) The Movements of the Spine in general. — Each intervertebral articula- tion is the seat of very obscure movements, whose separate study oJffers 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 flexuons column. When flexion takes place, the spine is arched upwards, the common inferior ligament is relaxed, the spinous processes separate from one AETICULATIONS OF THE HEAD. 335 another, and the superspinous ligament, becoming very tense, soon imposes limits to this movement. Extension is eJffected 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 coccygeal regions, but' is arrested by the ribs and the costiform processes in the dorso-lumbar region. A circumflex movement is possible at the two extremities of the vertebral column — neck and tail; for they pass easily from extension to lateral inclination, and from this to flexion, etc. Owing 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. In the Ox the intervertebral discs are much thicker than in the Horse. The common inferior vertebral ligament is very strong in the lumbar region. The superspinous dorso-lumbar ligament is composed of yellow elastic tissue. Tlie cervical ligament is much more developed than in Solipeds, in consequence of the greater weight of the head ; ^nd it presents a conformation altogether special, which M. Lecoq^ has made known in the following terms : *' On leaving the withers, the superspinous ligament ceases to cover the head of the spinous processes, and extends from each side in a wide and strong band, taking points of attachment on the sides of the processes, and becoming separated, on leaving that of the first dorsal vertebra, into two parts — a superior and inferior. The first reaches the cervical tuberosity in the form of a thick cord united to the cord of the opposite ; the other thins off into a band which is attached to the posterior half of the spinous process of the axis and to that of the third and fourth vertebrae. A production of the same nature, an auxiliary to the principal portion, leaves the anterior border of the spinous process of the first dorsal vertebra, and is attached to that of the fourth, fifth, sixth, and seventh vertebrae. The superior border of this auxiliary liga- mentous production 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 raphe extending from the occipital bone to the spinous process of the first dorsal vertebra. The Cat has no cervical ligament, and shows, instead, a raphe like the Pig. In the TJog 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 Log this substitution only takes place in the cervical region. The laminse of the first coccygeal vertebrae possess the principal characters which distinguish perfect vertebrfi©. and are united by vestiges of the articular bands which exist in the other regions of the spine. Article II. — Aeticulations op the Head. We will first study the two extrinsic articulations whick are the centre of the movements of the head on the spine — the atlo-axoid and occipito-atloid articulations. Afterwards, we will pass to the examination of the joints which unite the different bones of the head. 1. Atlo-axoid Articulation, (Preparation.— It suffices to remove the soft parts from around the articulation to expose the interannular, the interspinous, and the inferior odontoid ligament. To examine ^Journal de Me'decine Ve'te'rinaire' (Lyons, 1848), p. 122. 136 THE ABTICULATIONS. the superior odontoid ligament and the synovial 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. Articular surfaces. — To form this articulation, the axis offers its odontoid 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 union, — 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. h. Inferior atlo-axoid ligament, — This is a wide, thin, and nacrous- looking band, extending from the inferior face of the axis to the inferior tubercle of tlie 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. c, 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. — Thi^, 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 uuites. Its external face is in contact with the great oblique muscle of the head ; its internal responds, in its inferior half, to the articular 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, — Eolation, 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 eords^ rising in common from tlie summit of the odontoid process, and inserted, each on its own side, within thh 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 Fig the disposition is nearly the same as in the Carnivora ARTICULATIONS OF THE HEAD. 137 2. Occipito-atloid Articulation, (Preparation. — 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 pjg^ 81. expose the synovial membranes, open the sides of the capsular ligament.) This is a condyloid articulation. Articular 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 it everywhere. 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 rtloid cavity. Sustained above, below, and outwardly by the capsular ligament, they are related inwardly to the dura mater and to the fibrous tractus which, from the odontoid ligament, is carried to the in- ternal face of the occipital condyles. Movements, — Extension, flexion, lateral inclination, and circumduction, 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- ciculi ; 2, 2, Lateral fasciculi of the capsular ligament of the occipito- atloid articulation 5 3, Odontoid ligament ; 4, Interspinous ligament uniting the second and third vertebra of the neck ; 5, Fibrous capsule uniting the articular processes of these verte- brae.— A, Anterior in- ternal foramen of the atlas converted into a groove by the section of the bone ; B, B, Verte- bral foramina of the atlas •, c, c, Foramina replacing the anterior notches of the axis. 138 THE ABTICULATIONS. Fior. 82. 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 imion 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. Interarticular 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 is a 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 cajpsular ligament — surrounds the articulation, and is attached by its borders to the margin of the articular surfaces it unites. Formed, out- wardly, by a thick fasciculus of white vertical fibres (Fig. 82, 2), this ligament becomes grey- ish-coloured and elastic for the remainder of its extent, and greatly diminishes in thickness, 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 Eigot 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 TEMPORO-MAXILLARr ARTICU- LATION. 1, Interarticular fibro-cartilage; 2, External fasciculus of the capsular ligament. — A, Base of the coronoid process ; B, Neck of the maxillary condyle ; c, Mastoid process ; D, External auditory hiatus. ABTICULATI0N8 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 tibro-cartilage, is brought into contact with the temporal condyle, while the other is imbedded in the glenoid cavity of the opposite side. The horizontal gliding is effected from behind to before, or vice versa. 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 prevents their going further. It will be understood, after this brief description, 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. 5. Hyoideal Articulations, (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 temporoliyoideal articulations ; to the second belong the joints which unite the different pieces of the hyoid bone — the interhyoideal articulations, Temporo-hyo IDEAL ARTICULATIONS. — Thcsc are two amphiarthrodial joints, in the formation of which each 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-lOths 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. Interhyoideal Articulations. — 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 peripheral fibrous capsule. They can glide on each other in nearly every direction. (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.) 140 TEE ARTICULATIONS. Article III. — Articulations of 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 ; 3, The articulations of the costal cartilages with each other ; 4, The sternal articulation peculiar to the larger Euminants and the Pig. All these joints will be first studied in a particular manner, then examined in a general way as to their movements. 1. Articulations of the Bibs 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 posterior vertebra. From this arrangement arises two particular articulations belonging to the arthrodial class, which are named costo-vertebral and costo- transverse, Costo-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 vertebrae, 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 disc. Mode of union, — 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. Fi^. 84. ARTICULATIONS OF THE RIBS WITH THE VER- TEBRiE, AND OF THESE WITH EACH OTHER (UPPER plane). 1, Spinal canal, upper face, showing the common superior ligament ; 2, Interar- ticular costo-vertebral ligament ; 3, Inter- osseous costo-transverse ligament ; 4, Pos- terior costo-transverse ligament. ARTICULATIONS OF THE RIBS WITH THE VER- TEBRAE, AND OF THESE WITH EACH OTHER (INFERIOR plane). 1, Interarticular costo-vertebral ligament; 2, 3, 4, Fasciculi of the stellate, or in- ferior costo-vertebral ligament ; 5, Common inferior vertebral 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 jperiphera / 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 ABTICULATI0N8 OF THE THOBAX. 141 tlie head of the rib, and in diverging are carried over the bodies 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 capsular ligament for the head of the rib and another for the costal tuberosity. He probably viewed the synovial membrane of these articula- tions as such,) Synovial 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-TRANS VERSE 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 (Fig. 83, 3), a fasciculus of short, thick, white fibres, fixed on the anterior surface 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 vertebrae. 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 facet at its lower extremity. Mode of union, — 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. The 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 lying 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 Bibs to their Cartilages, These are synarthrodia! 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 articu- 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 cartilage, 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-xiphoid), under which passes the anterior abdominal artery. 5. Sternal Articulation peculiar 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 ARTICULATIONS OF THE ANTEEIOR 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. Article IV. — Articulations of the Anterior Limbs. 1. Scapulo-humeral Articulation. {Preparation. — ^Detach the Hmb from the trunk. Eemove 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 capsular ligament. The thin scapulo-humeralis muscle may be- allowed to remain in order 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. — Tn 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, ^xed 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 separate to the extent of from y^ to -^-^ 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 brachiij, 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 ; 3, 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 ABTICULATIONS. there is the atmospheric pressure, whose influence is of a certain impor- tance. This may be proved by removing all the surrounding muscles, when 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 scapulo-humeral permits extension, flexion^ abduction, adduction, circumduction, 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 freq[uently 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. Extension 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, addiction ; 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, Bog, and Cat, the synovial noembrane is not exactly inclosed by the fibrous capsule, but forms in front a cul-de-sao, which descends in the bicipital 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 -acromion 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-liumeral is that which has the m)st extensive motion; in movements forward and outward, the humerus can become horizontal; in those of circumduction 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 not to damage the ligaments to which they somewhat closely 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 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 before and behind, and is composed : 1, Of a double external groove ; 2, Of au ARTICULATIONS OF THE ANTERIOM LIMBS. 145 internal glenoid cavity, both radius ; 3, A middle ridge re- sponding to the middle groove of the humerus, separating the two preceding surfaces, and prolonged 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 union, — 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 principal extensor of the pha- langes, 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 slightly oblique downwards and forwards. h. The lateral internal liga- ment, also funicular, is longer, but not so strong as the pre- ceding. It arises from the excavated, on the superior extremity of the Fi^. 85. scapulo-humeral and humero-radial articu* lations, with the 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. — a, Tuberosity ot the scapular spine. — B, Superspmous fossa. — c, Sub- spinous fossa. — D, Convexity of the small trochan- ter,— e, Summit of the trochanter. small tuberosity on the inner side of the 146 THE ABTICULATIONS. superior articular face of tlie 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. c. 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 expand over the radius, where they become united with the inferior tendon of the coraco-radial muscle. In its external moiety it is extremely thin, and composed of fibres crossed in various directions. Lined internally by 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. Inflexion, the two bones do not approach each other directly, the inferior extremity of the radius deviating a little outwards. 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. lu the Dog and Cat, the external lateral ligament is very thick, and forms in its 1 Some grey elastic fibres which cover this cul-de-sac externally, have been wrongly described as a posterior membraniform ligament. ARTICULATIONS OF THE ANTEBIOB LIMBS. 147 inferior moiety a fibro-cartilaginous cap which is fixed on the ulna and radius, and united in front to tlie annular ligament of the superior radio-ulnar joint. This cap, with the last- named ligament, completes the osteo-fibrous ring in which the superior extremity of the radius turns. The internal lateral ligament is inserted by two very short fasciculi into the ulna and inner side of tiie head of the radius. A third fasciculus, deeper and median, much more developed than the first, and covered by the inferior insertion of the flexors of 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, which it appears as if about to join. In Man, the elbow articulation is formed nearly on the same plan as that of the Dog and Cat. The radius and ulna move together when the fore-arm is flexed and extended on the humerus. 3. Badio-ulnar Articulation, Articular surfaces, — The two bones of the fore-arm correspond by diarthrodial and synarthrodia! surfaces. a. The diarthrodial surfaces consist of four undulated, transversely elongated facets, two of which are radial and two ulnar. The first border, posteriorly, the great articular surface forming the elbow joint ; the second are situated beneath the sigmoid notch. h. The synartlirodial 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. See pages 75, 76. Mode 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. h. The peripheral hands 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 ligament. The internal fibres are united to the internal humero-radial ligament, and to the small ulnar tendon belonging to the short flexor of the forearm. 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 Oxj ossification of the superior interosseous ligament is constant at adult age. In the Dog and Oaf, we have already seen fp. 87) that the radius and ulna are not fused to each other, but remain independent during life. They are united in their middle portion by an interosseous ligament, and join by diarthrosis at their two extremities. These animals therefore exhibit: 1, An interosseous ligament^ 2, A superior radio-ulnar articulation; 3, An inferior radio-ulnar articulation. Interosseous ligament. — It is composed of very resisting white fibres, attached by their extremities to the bodies of the bones. Notwithstanding their shortness, they are loose enough to allow movements taking place between the radio-ulnar articulations. Superior radio-ulnar art'u ulaiion. — This is a trochoid articulation, which only allows movements of rotation or pivoting. 148 THE ARTICULATIONS. The articular surfaces which form this articulation are: in the ulna, the small sigmoid cavity, a surface excavated in the lateral sense, and semicircular ; in the radius, a cyh'ndrical half-hinge received into the preceding cavity. To unite these there is an annular ligament, a kind of fibrous web thrown around the superior extremity of the radius, fixed inwardly on the ulna near the inner extremity of the small sigmoid cavity, attached outwardly to the external lateral ligament of the elbow articulation, and confounded superiorly with the anterior ligament of the same articulation. Tliis fibrous web, in uniting with the fibro- cartilaginous cap of the external humero-radial ligament, and joining the small sigmoid cavity by its internal extremity, transforms tliis last into a complete ring, covered with 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 incrusted 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 si,irmoid cavity, .but also on the internal face of the two ligaments which complete this cavity. Inferior radio-ulnar articulation. — This is also a trochoid articulation analogous to the preceding, but inversely disposed. Thus, the concave articular surface is hollowed on tb radius, outside the inferior extremity ; the convex surface lies within the ulna. These ^Itwo facets are very small, and are maintained in contact by a diminutive peripheral fibrous capsule. A strong interosseous ligament, situated under the articular facets, also consolidates this diarthrosis, and concurs by its inferior border to form the antibracliial surface of the radio-carpal articulation. A small synovial capsule is specially devoted to this articulatit)n. Mechanism of the radio-ulnar joints. — The play of these two articulations is simultaneous, and tends to the same end; that is, to the execution of the double rotatory movement which constitutes supination and pronation. Supination is when the ulna remains fixed, and 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 ulna 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 pronati^ )n. 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 palmar 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 upper 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. — Eemove the tendons from around the articulation, detaching their sheaths, but taking care of the ligaments.) These comprise : 1, The articulations uniting the carpal bones of the first row to each other ; 2, The analogrous 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 of the First Eow to each 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 * 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. ABTICVLATIONS OF THE ANTEBIOB LIMBS, 149 external lateral ligament and the inferior tendon of the external jflexor 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, imites the first to the second bone. The two others, situated between the three last carpal bones, are* confounded with the corresponding anterior ligaments. Articulations uniting the Carpal Bones of the Second Eow. — These are arthrodial articulations, like the preceding, but numbering only two. They are fixed by ^2^0 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 b'^nes is separated from the anterior ligament by one of the diarthrodial facets L itween these bones. Eadio-carpal Articulation. — 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 irregular, presents ; 1, Outwardly, a wide groove, limited in front by a small 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 tliat of the preceding groove and, like it, completed by a small anterior glenoid cavity. The carpal surface, moulded exactly on tlie radial, offers depressions corre- sponding to the projections on it; and vice versa. 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. 6), 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