wil OOLEShbasA | Come of RAL i Yr Ae PLY Bee SSEMSLe Oy + Text ie FEEMEN TS. @F MAMMALIAN ANATOMY. DAVISON. MAMMALIAN ANATOMY WITH: SPECIAL (REFERENCE TO THE CAT BY ALVIN DAVISON, PH.D. EX-FELLOW OF PRINCETON UNIVERSITY ; PROFESSOR OF BIOLOGY IN LAFAYETTE COLLEGE WITH OVER ONE HUNDRED ILLUSTRATIONS MADE BY W. H. REESE, A.M., FROM THE AUTHOR’S DISSECTIONS a) a ) = ® » > a> e J +9 ‘ —s. 5 Ay yO: ’ s 9 2. TS, Yo 9 3 7? © 4998 203 2A 2 >) 2 2 o © = *** Study nature, not books.’’ oe eae Sat saree sce8s Seago,» SO a an ate © ) @ y ~) > i », PHILADELPHIA I~ BE AKIS £ ONS. SON=&.CO, 1IoI2 WALNUT STREET 1903 THE LIBRARY OF CONGRESS, 7 : i Fa peas g25 8 ay oo oe 6k zoo me $69 3~) r o . BLakisTon’s Son ‘Cos COPYRIGHT, 1903, BY P ; Mutou gees 7 vue AES en vo, i) 3 Lae) veues < ¢ t gow “ete “oye vweeue : : ey owe - ’ . . 0 ney,” eevee oe c r' ove «ewe >w ; oe Ms e 66 ee : ee Z< - Tee per oe ew a-ao a (he te A a * o > 0“ ¢ | ’ . tus ac oi ; co | a a ae “ne fv : zu 4 a w PREFACE. Huxley after years of pedagogical experience reached the conclusion that it is unwise to introduce the beginner at once to new and strange forms of microscopic life when it is possible to use a subject of which the student is bound to know something,—the elementary anatomy of a vertebrate animal. The late T. Jeffrey Parker and numerous other eminent zoologists likewise advocate be- ginning zoological work by studying one of the higher animals. Since the majority of college students have time for only one year of zoological work, they cannot acquire a fruitful knowledge of both vertebrates and invertebrates. A study of the former enables one not only to become familiar with the anatomy and physi- ology of his own body,—a matter of vital importance,— but throws a clear light on the significant problem of organic evolution such as is not to be derived from a study of invertebrate forms. Inasmuch as the genea- logical histories are best worked out among the Mam- malia, and since a careful study of the anatomy of the cat familiarizes one with the anatomy of the human body, as is evidenced by the fact that our best medical schools now advise their prospective students to dissect either a dog, a cat, or a rabbit as a preparation for their later work, it is apparent that a knowledge of the mam- mals is of the greatest worth. - This brief work is intended to acquaint the student Vv vi PREFACE. with the general structure of the cat, and at the same time introduce him to some of the most important mor- phologic features of the Mammalia. The following works are useful for reference: ‘““Anatomical Technology,” Wilder and Gage; “‘ Anatomy of the Cat,’’ Reighard and Jennings; ‘‘Mammals Living and Extinct,’ Flower and Leydekker; ‘‘Primary Factors of Organic Evolution,”’ E. D. Cope; “Vertebrate Zoology,” J. S. Kingsley; “Anatomie des Hundes,”’ Ellenberger and Baum; ‘“Human Physiology,’ Schenck and Giirber; “ Osteology - of the Mammalia,’’ Flower; ‘‘ Human Histology,” Piersol. In the preparation of this book I have consulted a large number of works on human and comparative anatomy and physiology. Those giving most assistance are the works mentioned above, in addition to ‘“‘Mam- malian Anatomy’’ by Jayne, “Anatomie Descriptive et Comparative’’ by Strauss-Durckheim, ‘‘ Nervése Central- organe”’ by Edinger, and ‘“‘ Vertebrate Paleontology”’ by Woodward. I am especially indebted to my artist, Mr. W. H. Reese, of the Phillipsburg High School, for the care and patience exercised in making the drawings from my own dissections. Mr. D. S. Hartline, of the Bloomsburgh State Normal School, has read the entire manuscript and made valuable criticisms. Above all, I have to thank Prof. J. S. Kingsley for numerous valuable suggestions and important corrections in the manuscript. Atvin DAVISON. EASTON, Pa., September, 1903. CONTENTS: JUS EERO TOY OT CTIUG Tis a A Ore RO, Ne ck a ee ee, hie PetOlOcieal Selences e992 7 be oe epi SOM Ciacsmestion Of tae Anitial: Kingdom, 25 oo. 2 ioe ks se eee ‘Preparation aud: Preservation of Maternal, 2. sie) see CENERAT STRUCTURE OF Ao VERTEBRATE (000 0 20. oe ee ira ott eiebines ee (Ne aaa ee ee OF eh ar aat NS “CEN: SECIB 28 JOLY gS a ah lal Pea Ef SOE ee Reem Pe te ae a ee General Terms Used in Description of Bones,__________-_-_-- Seb OT Olt by OmeSeet, x tues elem kit tun meee Ae tO Sears Eee “SSAC EC ERTON ia BONE (© Ta Oe ee ad Sa ee no OneCoMOn Mee Skthline s,s PLS. Sor ee ed SOR ircaicmm lead) pera es rds Nee Me ons SOU OE ee eae UL ee. MIGENE | OMONEE Seve ae eae toy Bre es Et ae b BS ae MTS A TOS I Ec et sass te Oe et ecm Rw A Sere pga eel eM ea Ore ORE ANC UO. IGE SRION, oe hm er eee eel eee a zs) ra Sint aw eae oC C2 Tl |e eae la ee, Stag 2 a ys sp Ee na a PNCEESSOIY™ Cadmcs OL WISeStiOly . ee ae Pete ORE Miki come me et ce ae eee ae Mee ene Set mee ls Eo Ue Dae VASCULAR SYSTEM, 2 =e e7 ¥. 2} > Be oe ee Ne PAT a Sey 2 EL Oa Arteries of Trunk. ATPeiIeS Ob INGCK ania teagd. = otra S48 wes ie 8 eee PRE ECTHIOS, 4On 5 EMO ceeiemele Tito a= san, ee ee Me eo ERS ites oly Mexc iviica mie Wita, 22 ee eS Sa ee SO ee ks ‘\GIGIONEIS Sy S (ETI ec RS IS San oc ee ge gg ee LS iDEA) Og ELL CMPA SN GASY CS 0 gt po rl ea a at TD ig SESS SaaS gh Ss oe we gps al ett ge 2 ge Pa GEOR OR OVGRD ING soe ee ela Pelee os PSP PE WA ee ERGREtORY AND KREPRODUCIIVE SYSTEMS, 9-92... __ 2) ei Glands of the Skin, Vill CONTENTS. PAGE Urinary. Orgams, -2 22 22.) Js. Se Female Organs of Reproduction; =2* = ew 177 Male Orgatis of Reproduction, 2.222 Pe 25s see ee ee 180 INERVOUS SYSTEM) ee es 186 125 25 | | ho: nee eete er Mem NS Aig Se eS ee 186 External’ Features: so): = 55ce = ee ee eg ee ge 187 Internal. Structure; 2 SS ee eee es 192 Spinal Cord, 2 2 22 Ee a ole ee ee 205 Fiber Tracts of the Central Nervous System, .-_-.2--__- == ==] _ 210 Peripheral, Netvesy 2. 228 ee ea ae ree ae ees 216 Cranial Nerves, 2502252 se eg ip beeen 216 Spinal ‘Nerves, 2222 2 5 ee eee eee ere 218 Synipathetic System). ss se es See ee ee 2269: Organs of Sénuse, 20... es es ee ge ee 25M Cutaneous; 22 2 25 a ree Ee ie ee ae 251 Olfactory seo ee per ae ee ce eg 232 Gstatory,. 8 4 pF sa ee ea eee ee 232 AYG cb een aes A te ore IE eit ee es 233 Auditory; 2222.22 2S SNES i eee hat ee oe Bee eye eee 237 INDEX, =~ 220 2s ee ee eee rca 5 oe a a ee 243 ky OMNAAMHARWNHeEE bist, OR AELUSPRAFIONS: Ree S Oe Clit lett titel erie ea A AGE ye a ee ek es sp ALTE SC TURES NCCT es A ae gg ie Re pec ee Pp Miacammatic View Of Operationjifor Injection, 22302 otek . Method of Making Incision in the Carotid Artery for Injection, _- a Methodtot Inserting the Canniula imto.a) Vessel;.2_.-22- 2222 ; Palmar Aspect of Cat’s Paw with Cannula Inserted, __-_-.--++ S bilat epithelium, Cells from the’ Mouth; . L220 0) 2. 222s lee Melrmroleimateoty: pNiSele: sellil ih ade Ot We Nee ee ee Octo Cartilage. 2st. s De Tin oe ee SW Riealte iys Ah S BN Ze Miners ol Voluntam Nuscless4 0 ieee S22 Le Pehiverscot Commeetive: lisse ses. WLS o ee ge oe Pe . Longitudinal Section of the Humerus of a Kitten,_______-_-_-_ Pronrcticma secon, of the Memiur, i os {oo ee le EAS PCLOss-scenomgorcat.s: Femi. 0. Se uke et i Oe . Diagram of the Bones of the Mammalian Skull Viewed Laterally, Fe DOisal: Aspect sor “tne Cat-st okt fo ee eee ee . Ventral Aspect of the Skull with the Left Auditory Bulla Re- EO Gln ees (el NHL meh” oO ey Nee RON ie SNe RL PCut outiace olay oagittaliy: Bisected Skill} S22 go. 222 Bose PMesalvon laner Aspectiof the Mandible) “2... = 2 see 2 tLe . Ventral Aspect of Larynx, Hyoid Bones, and Tongue, ---_-___-_- tater aspect) of the: Skeleton, 22... 28 5 Seka ee El piieOlecd trie kas si Olio wae At eee re Set ee Pee me OLOcaid al eASpeet Or wAtlaS Vote ea ee Pe ee Ss ee SOraie ASNeCCt OP Che HA MIS, haus Pee is 1 3 ee . Latero-caudal Aspect of a Thoracic Vertebra,____________-_-- meandal Aspect of Fourth Ijumbar Vertebra, 222-2 +2222 22 MeWOrcd le nspeet Ol tie Saerutd, 992 22 ee Lo eee ee . Ventral Aspect of the Bones of the Thorax,__________________ Meanie eACHeCE OF Simi Ribios ele 2 fee oo eS ee ae meatal, NSpeCt Ok tie, ocapiila, ew. -. 2 Slee ee 2h ee et mbamealuAspectvor tie Clavicle a. 2502 ue ee mecepialic Aspect of the Munterus,... 2-2 =... 2-222 ~_-2as825-. ix X LIST OF ILLUSTRATIONS. FIG. PAGE 33. Lateral Aspect: :of ‘the: Wilma, 225 222 a ee ee 70 34. Mesal Aspect of the Radius, .< «0508 22 ee aes ee eee 71 35. Genealogy of the: Horse}2_2 2 = £2 ee 73 356A. Dorsal Aspect .of Cat's: Manis, 2233 eee 74 36B, Generalized ‘Type of Carpus,< =2 32 2 ae e ee ee ee ee 74 37. Lateral Aspect of Forelitnb of “Equus. 222) 5 soe ee eee ee 75 38. Lateral. Aspect .of hinomitate Bone," eee ee 80 39; Ventral Aspect of Innominate Bones, 2525 26 ee eee ee 80 40. Caudal Aspect of Petit = 222 2 ee eee 81 41. Cephalic Aspect ‘of Tibia, 222.6 222 ae ee eee 82 42. Mesal Aspect of Fibttla, “L225 5 2 ee 83 43. Dorsal Aspect of, Hind-foot, 22) 522 eg ee 85. 44. Diagram of a Diarthrodital\joimt, 2 eee 89 45. Lateral Aspect of DissectedsKarce qomin) = Ses eee 90 46, Caudal Aspect of Kinte-jointsy 52 te Se eee 91 47, Ventral Aspect of Trunk and Neck Muscles, .-.._..-.._._._-_ 99 48, Lateral Aspect .of the Mauselesmor tie Canty 2224s es ee 104 49. Lateral Aspect of the Muscles of the Thoracic Limb,_-_-_____- 105 50. Mesal Aspect of the Muscles of Thoracic Limb,__.____..__-.-- 2 51. Ventral Aspéct of the Muscles oi Trank and Thigh, ==.) __ = 113 52. Lateral Aspect of the Mascles ofaneuler ie) > ei nee eee 113 53, Catidal Aspect: of the-Mirscles sof sCras and Nooat;2. = 114 54. Diagram of the Cie Oredns-or thiewoab: 2 ee ee 118 55. Dorsal Aspect of the: Toague aud Varyam 3 oo 8s Sw aes 119 56.. Longitudinal Section ot the Canine Toothy 2 = ee 120 57, Lateral Aspect: of the) Permanent Dentttion 22922 = aes 121 58. Ventral Aspect of the Alimentary Canal, 252552. )42 Sie 127 59. Transverse Section. of the Catt ee ee eee 128 60. Cross-section of the Cardiac End of the Stomach,_____________ 128 61, ‘Gastric Glands) 20.4220.) See eee UP ee Se eee 129 62.. Cross-section. of, the Small dutestine =e 5 Se ee 130 63a, Villi and Glands-of Intestine, < ate 2 e248 es eee 131 63B. Photomicrograph of Intestine with Bienes Tnjeetedse= 22151 64, Salivary Glands, 2.222 -0a2 Soe se 132 65, Photomicrograph of Section of the: Diver, 2... 5 Sa 134 66. Diagram of the Stomach of a-Rimumant, 9: 222 eee La7 67, Heart Viewed Venttaliy,-22.7 2 a eee 141 68. Heart Viewed Ventrally with Caudal Third Cut off,____-_-.-_ 142 69, Heart Viewed Dorsally; 22220 22222 ee peel. 142 70; Chief Arteries of the Triink, 222s 232 eee Ce SR 144 71. Ventral Aspect of the Arteries of the Head and Neck,--_-_-_--_- 146 72, Atteries of the Forelimb, ..-. -2@bll2eloe eee eee 149 73, Arteries of the. Leg, . 2... ... =< cpee 152 LIST OF ILLUSTRATIONS. xi FIG, PAGE 74. Cross-section of Artery and Vein, ----- jes RS a go ere ok pee eae ee 153 See CLIMB MeS = De Dee mente ES lie eee eo el ee 154 OME mene Galler tae ae Hehe ew dias See eae be ee bee 155 i epeieetiain oyStelt Ol a Rabbit, 222282. ol. esc kk eS. 158 PERG Chia ll si Shen Oly a, Wain iar oye Jo So a 158 78. Ventral Aspect of Chief Lymphatic Vessels of the Cat,._____- 163 79. Photograph of the Lymphatic Capillaries and Vessels of Cat’s Ear, 164 S0: Diagrammatic Transverse seetion.of the Chest, ....-2-.-=2._- 170 81. Photostaph of a Langs Corrosion of a Puma,-_._.-_-.-2'-_.__.. 171 oo, Reiman Ob. enoneniole, 2. 2 te es 172 83. Ventral Aspect of Female Urogenital System, -_____.._.___-. 175 64. Median, Voneitudinal Section” of a Kidney, 2. 222 =" 2 176 So iasiatit or nometnte OF Kidneyes 2205 4 os. Seta 176 SOM OOC EO Olns ONC yout Meek ee 2k ees aw Ble eee eke 179 8/. Ventral Aspect of Male Reproduetive Organs, __.......5...=- 181 ae OHNE ThE CELO DOs ween ee ate Nl es SE Ie Be 182 Son Dorsallyacpeet, Of tae brait, 253 oe Bo ee Ship 189 Sma eitial ASHeCt, Oh tite Biatiy 20.5 42 Se oa ee 2a ae NS 190 ie Wider OF the: Wemtreles~. seo. se Lee ee ee 192 See Sastital: SecuOmROt vue. tai, 29 2 9 62 ae 194 93. Dorsal Aspect of the Brain with the Cerebellum and Portion of Cerelsaimialveni@uediect i. as ne Aamo ers on ee 197 94. Cross-section of the Brain Caudad of the Optic Chiasm,_____ 199 95. Cross-section of the Brain through Anterior Commissure,____ 201 {or Diagiainmatie Seetion. of Spittal: Corda.) 2.23 5s 8 207 OiaIN Sta epee a fees oe Aa nee ea. Rg bie Loh 8S Za oi et, ee 208 98. Diagram of the Relation of Cells and Fibers in the Spinal Cord, 209 OOF Diagrameon come —lijser-tracts,«_- 8 222202 ek 2 100. Diagram of Chief Fiber-tracts of the Mammalian Brain,______ 214 Ole Weattale Aspect of the’ Brachial Plextig;.2 #022 se) ee 220 Og) Mentrab Aspect of the “Nerves: of the Pelvie Wimb, = 22522. 22 225 NOS Cepia lic Mali of Sympathoetie System, = 2s. oS eh 228 Oa Carica Elali Of. oy mpatietic Systettese 26. 22a se 229 RO Seeeoneiiniam COLPUSCleN ss < -250! n, Nucleus of the cell. n, Nucleus of a cell. muscular, digestive, respiratory, vascular, excretory, re- productive, and nervous. The relative locations of the various systems are represented diagrammatically in Fig. 54. The organs have the same arrangement throughout all the orders of mammals. Moreover, the minute structure of the same organ is so similar in the different species that in most cases one can scarcely distinguish them by micro- scopic examination. The organs are composed of four 28 GENERAL STRUCTURE. 29 classes of tissues: Epithelial, which covers all free sur- faces; connective, forming the bones, binding together the muscular fibers and elements of the nervous system and making up cartilage and ligaments (Fig. 11); mus- cular, composing the greater part of the muscular system; and nervous, consti- e e ° fae SS) tuting the nervous system (Fig. 85). Oe a ® The naked eye is unable to distin- ee EP : . we es guish the elements of the tissues, but ais the microscope reveals the fact that - each kind of tissue is formed of either sare ge Re cells or fibers or, as is most frequently 150. the case, a combination of both. The different relative arrangements of these anatomic elements, together with their morphology, permit one to know from what organ any particular section of tissue under consideration has been taken. These ultimate units of structure are still further resolved into parts by the chemist, who has shown that they are composed largely of carbon, hydrogen, oxygen, andsmitrogen:.- Since there can be ne energy developed in the body without the disintegration and consequent death of some of the particles composing the Fic. 10.—Fisers millions of tiny cells, it is plain that Rice ety they must have their losses replaced in n, Fiber; t, tendon. order to continue their existence. There- fore a method of preparing the food for the use of the cells, and a way of transporting it to each of them are necessary. The former is accomplished by the digestive system, which, through the agency of the salivary, gastric, pancreatic, and other glands, transforms the food into 30 ELEMENTS OF MAMMALIAN ANATOMY. a special liquid state capable of being absorbed by the millions of minute finger-like villi of the small intestine (Fig. 63). Thence it is transferred by the lacteal vessels and veins to the heart, whence it is conveyed by the arteries to their capillary distribution in the neighbor- hood of every cell in the body. The dead matter or waste material resulting from the cell activity is of two kinds, gaseous and liquid. Both diffuse through the capillary walls into the blood. The former, which is carbon dioxid, is carried to the heart and thence by the pulmonary arteries to the lungs, where it passes into the terminal branches of the trachea, and finally by expiration reaches the exterior. The liquid excretion is transported by means of the veins and arte- ries to the kidneys, where it diffuses through the walls of the capillaries into the minute tubules opening into the ureters leading to the bladder. It must be remem- bered that the material known as feces passed out of the alimentary canal through the anus is not an excretion GENERAL STRUCTURE. 31 of the cells of the body, but merely that portion of the food not transformed into a condition permitting it to be absorbed by the villi. In addition to these systems necessary for the main- tenance of life, the cat requires a means for supporting the body and moving about, furnished by the osseous - and muscular systems. The osseous system serves not only for support and locomotion, but also for the pro- tection of the delicate vital organs. The skull and spinal column contain the brain and spinal cord, while the heart and lungs are well shielded by the dorsal vertebre, the ribs, and sternum. Likewise the muscles ward off serious injuries from the blood-vessels, as they cover to. a considerable depth nearly all large arteries, and also aid by their contraction in moving the lymph through the numerous lymphatic vessels extending from the extremities to the jugular veins. These systems previously described are capable of per- forming their functions only when supplied with nerves through which impulses can be transmitted from the brain and spinal cord. Stimuli sent by the brain or cord through the nerves cause the gastric juice to flow into the stomach, the bile and pancreatic secretions to be formed and poured forth into the intestines, the kidneys to eliminate the waste from the blood, the heart to beat, and the muscles to contract and relax. The only system which is not absolutely necessary to the life of the cat is the reproductive; but this is required for the continuance of the species. It is not, however, functional during the entire life, but as a rule only from the end of the first to the tenth year. 32 ELEMENTS OF MAMMALIAN ANATOMY. PRACTICAL QUESTIONS AND SUGGESTIONS. . What advantages are derived from the study of mammalian anat- 2. Define morphology and state a fact from that science. . What two sciences does biology include? What five sciences are included in zoology? . Make a physiologic statement concerning the heart. . State five facts belonging to the science of distribution. . What is taxonomy? . Name five classes of vertebrates. . By examining specimens discover what external feature distin- guishes a reptile from an amphibian. 10. Un 12: malia. LS» 14. 5: 16. i 18. 19. 20. differ 21 22 Do all mammals have hair? What habit is common to no other vertebrates except mammals? Give two points of difference between the two subclasses of Mam- Name the ten orders of Eutheria and give an example of each. Which orders derive their names from the habits of the animals? Which orders derive their names from anatomic features? Which orders are aquatic? What is the ultimate syllable of all family names? Explain what is meant by binomial nomenclature. Name three families of Carnivora. Examine specimens and determine wherein the teeth of Canide from those of Felide. What two rank names constitute the scientific name of an animal? Give the scientific name of five Carnivora, two Ungulata, and two Primates. 23. Uae 29: Define organ, system, tissue, and cell. Name two organs belonging to each system. How do the elements of the four kinds of tissue differ? EXTERNAL FEATURES. The cat, like all other mammals, possesses two well- defined skeletons, the endoskeleton, consisting of the true bones, and the exoskeleton, composed of the skin and its appendages. ‘The skin invests the body completely and is continuous with the lining of the digestive and uro- genital canals. It varies in thickness in different regions, being very thin on the lips, ears, and eyelids, and ex- GENERAL STRUCTURE. a3 ceedingly thick on the pads of the feet and on the ventral neck region, where, in contest with an enemy, it is most likely to be seized. A fibrous connective tissue binds the skin to the subjacent structures. In some places the union is very firm, as on the distal parts of the limbs and the head, while in other regions it is loose, as on the lateral aspect of the trunk. The skin consists of an external layer, the epidermis, and, beneath this, the dermis or true skin, designated the corium. ‘The epidermis is composed of numerous strata er epituchal cells. “Those vom .or mear the surface dre much flattened while the deeper ones are more or less cubical. As the superficial layer desquamates in minute fragments, forming what is commonly called dandruff, it is replaced by cells developed from the deeper layers. The portion of the epidermis adjacent to the corium or cutis vera contains the coloring-matter of the skin, and is known as the rete mucosum. At the orifices of the internal passages, such as the digestive and genital tracts, the epithelium changes to a soft delicate nature, and is then known throughout these passages as mucous membrane. The corium or dermis is a form of fibrous connective tissue whose deepest portion forms the white fluffy areolar substance cut in removing the skin. In many regions just below the true skin is a layer of adipose tissue, which when examined under the microscope is seen to be composed of numerous globular fat-cells sup- ported by fibrous areolar tissue. The seven pads on the forepaw and the five on the hind one consist of greatly thickened epidermis, the corium, and masses of fibrous connective tissue enveloping many fat-cells. The sebaceous or oil glands lie in the corium, and by means of a duct open into the hair follicle near the sur- 3 34 ELEMENTS OF MAMMALIAN ANATOMY. face. The sudoriparous or sweat glands, composed of coiled tubes, are present in the subcutaneous tissue, from whence a duct extends to the surface. Although there - are no blood-vessels in the epidermis, numerous nerve terminations are present in the deeper portions. ‘The true skin is richly supplied with both nerves and blood- vessels. The claws produced by a special modification of the epidermis are-among the most important appendages of the skin. Five of these are present on eaclt foreicor, while only four occur on the hind one. At the root of each claw, the dermis forms a crescentic fold over it, and beneath is a number of papille richly supplied with blood-vessels. This entire structure forms the matrix of the claw, which is set around the terminal part of the distal phalanx of each digit. Claws, or some similar structures, such as nails or hoofs, are present in all mammals except the Cetacea. Another important appendage of the skin is the hair, which covers the entire body except the tip of the nose and the pads of the feet. Its length and color vary with the variety of the cat. The Mombus cat of Africa has short stiff hair, while the Angora or Persian cat is remarkable for the length and delicacy of its soft fur. The hair, like the nails, is an extreme modification of the epidermis. Each hair grows from a papilla at the bottom of a small sac, the follicle, which is a depression in the corium. The central part of the hair is the pith, and the external portion, formed of thin overlapping scales, the cuticle. The coloring-matter lies in the super- ficial scales, and may be disposed in such an irregular manner that one-half of a hair is white, and the other half yellow. The large hairs on either side of the nose are known GENERAL STRUCTURE. 25 as vibrisse. Their roots are provided with delicate nerve- endings of touch, so that the animal may find its way . with ease through dark narrow passages. ‘There are a few long hairs above the eyes, forming the eyebrows, but no eyelashes are present. Most of the hairs are inserted obliquely into the skin, but when angered the cat can erect them by the con- traction of a small muscle passing from the skin to the hair-bulb. : On some mammals the hairy covering is partial and limited to particular regions; in others, as the hippopota- mus and the Sirenia, it is very scanty, but scattered over the whole surface; while in the Cetacea it is reduced to a few small bristles about the mouth. Some kinds of hair, as those of the mane and tail of the horse, are shed and renewed annually. Most mam- mals have a long hairy coat in winter which gives place in spring to a short coat. The Arctic fox, hare, ermine, and numerous other animals of the colder regions undergo a complete change of color in the two seasons, being white in winter and brown or gray in summer. By this protective coloration they escape many of their enemies. THE SKELETGH: The number of bones in the skeleton of the cat varies with its age, since two or more bones separate in the young may form one mass in the old animal. The three portions of the innominate bone which are distinct (Fig. 38) in the young, become fused in the adult. In very old age many sutures of the skull become partially or wholly obliterated. Inthe young adult cat the number of bones, exclusive of the teeth, ear bones, chevron bones, and sesamoid bones, is about 233. The sacrum is reckoned as one bone, though composed of three coalesced verte- bre. The structure and embryology of the teeth show that they belong to a different category from the bones. The ossicula auditus, or ear bones, are the malleus, incus, and stapes of the middle ear. The chevron bones are eight in number, attached to the ventral side of the vertebre of the tail. The sesamoid bones number about forty, of which the patella, or knee-cap, is the largest. They are formed in the tendons where there is much pressure or friction, as upon the volar surface of the - metacarpus. The outline on page 37 gives the classifica- tion, names, and number of the different bones of the skeleton. GENERAL TERMS USED IN DESCRIPTION OF BONES. In reference to shape the bones are spoken of as long, short, flat, and irregular. Long bones are those having a shaft or diaphysis in which is a cavity filled with marrow, and two enlarged extremities or epiphyses (Fig. 13): 36 AXIAL SKELE- TON APPENDICULAR SKELETON Hyoid bones Thoracic limb Pelvic girdle inomballs.) si 5. cen 512 Bthmorde ee tony ; demporaly = ee ee 2 Cranium Ranictals Geass ecy 2s. 12 Inferpatictaly sess. 5 Oceipitaley ==] a I Sphenordhaiae. 2s 11 Bremaxillaiye sts. 2 Miaxalilatayne ser ese 2 Palatine, 232. .6. = *- 2 Viomenic 2) 5 6.8 t I Face Maxilloturbinal, 2 INaSalliacicas esc oe a7) achrymall cso el 2 Malar or Jugal,. . . 2 Mandiblet ne 2%... I Tympanohyal, ... 2 Stylohyali 2). .°: 2 Pe piliyaliete se Goce 2 Ceratohyaliery = 2 2 Basihiyal 202 «2 2 I \ Dhyrohivaly ie o8. .%. 2 Cervical vertebra, . 7 Thoracic vertebre, . 13 Vertebral column Lumbar vertebrae, . 7 Sacral vertebre, .. I Caudal ee ees ate 21 Rubs apa soneearae seid: 26 Stenmuimiy 2.5 2). I h t cirdl Scapulay i 2) = 2 Spo Sea Clavicle ns earn. es: 2 EMImerus, Woe 2). es 2 iliaiai 952), boc feo IRAGiUSs ees eee 2 Seapholunary- 2) 2 Cunleitonm—y ss aoe Risitorms: oases 6 2 RrAapeziuniy ess meee 2 Carpus Drapezoid), 9. = % (hs. "2 Macnumty ss 2 22.2 Wineifonnpeee eo 2 Metacanpiisne eid) suns ane a 10 a Proximal se: ae. 10 eanees 1 Middle oe Ape 10 Distal sss cos sles 8 innominate; -- .: 2 Femur, 2 Rarellae ver sys) aces 2 Tibia, 2 Fibula, 2 Astragalus, 2 Calcaneum, 2 Scaphoid, Bee oe Entocuneiform, .. 2 Tarsus Mesocuneiform, 2 Ectocuneiform,... 2 Guboid. lee. ae 2 Metatarsuss. Sachs se8. ous Se MIO) Phalanges | MAKI See BOS WEIS) 8 38 ELEMENTS OF MAMMATIAN ANATOMY. femur, fibula, metacarpals, and phalanges. Short bones are those not elongated and with no medullary cavity: tarsus and carpus. Fic. 12. — LONGITU- DINAL SECTION OF THE HUMERUS OF A KITTEN. h, Epiphysis for head; c, cartilage; b, bone; m, medullary sub- stance; 0, epiphysis for olecranon pro- cess. Flat bones are plate-like, with a layer of cancellous tissue between two layers of compact tissue: parietal, scapula, and innominate. Jrregular bones are those which have an ex- ceedingly irregular shape: ethmoid and vertebre. The aspect of a bone is the portion seen when viewed from a given direction. The border of a bone is the margin, edge, or ridge at the juncture of two surfaces. Proxt- mal is used to designate the portion of a structure nearer the axis or spinal column, in distinction to distal, which signifies the part farther removed from the axis. Cephalic indicates the part of an organ nearer to the plane passing just beyond the head and per- pendicular to the spinal axis, while caudal is applied to the other part of the organ nearer to the perpendicular plane at the end of the extended tail. Sagittal refers to the plane bisecting the animal in a vertical and longitu- dinal direction. Mesal and lateral are adjectives, the former meaning nearer to the sagittal plane and the latter more remote on either side of that plane. Proximad, distad, cephalad, caudad, mesad, and laterad are adverbs indicating direction in accordance with the adjectives to which they are related. THE SKELETON. A process is a projection or elevation. hr A tuberosity is a rough obtuse pro- cess. A tubercle is a small and usually more or less pointed process. A condyle is a rounded and somewhat elongated smooth articular process. The distal end of the femur presents a pair of condyles (Fig. 40). A fossa is an irregular depressed area (Ene 30): A foramen is an aperture for the pas- sage of vessels or nerves. The shaft is the body or middle por- tion of an elongated bone. The head is a spheroidal prominence at one end of an elongated bone (Fig. 40). The epiphysis is a small process of bone ossified from a separate center. In the young animal it is attached to the main bone by cartilage, but in the adult becomes a part of the main bone (Fig. 12). The femur has four epiphyses, one for the head, one for the distal extremity, and one for each trochanter process (Fig. 40). With the exception of the pha- langes, metacarpals, and metatarsals, all of the long bones have an epiphysis at each extremity. In the human, these epiphyses do not unite with the shaft betore the sixteenth year. Dzploé is Fic. 13.—Loncitu- DINAL SECTION OF THE FEMUR. md, Medullary cav- ity; d and h, can- cellous tissue; ¢r, cancellous tissue of trochanter pro- cess; b, compact bony tissue. the spongy layer of bone between the compact surface layers of the flat bones (Fig. 18). 40 ELEMENTS OF MAMMALIAN ANATOMY. The articulation of a bone has reference to its contact with other bones by means of joints. STRUCTURE OF BONE. Every bone is completely covered except on its articu- lating surfaces with a tough membrane, the periosteum, which serves for the attachment of muscles, and the renewal of bony tissue in case of injury. The long bones contain a cavity, the medullary cavity, filled with marrow Fic. 14.—CROSS-SECTION OF CAT’S FEMUR. ™ 5. cp, Compact tissue; cn, cancellous tissue; en, endosteum; mc, medullary canal; pe, periosteum. (Fig. 12). This cavity is lined with endostewm, a mem- brane similar to the periosteum. The shaft of the long bone is composed mainly of compact bony tissue through which extend longitudin- ally intercommunicating microscopic channels, Haversian canals, for the conveyance of blood-vessels, nerves, and lymphatics. The lacune, or spaces for the bone cells during life, are arranged concentrically about the Haversian canals. The canalicul1, or processes of the lacuna, communicate THE SKELETON. 4I with one another. At the extremities of the bones the place of the medullary canal is taken up by cancellous tissue (Fig. 13, d), the compact tissue being very thin. The flat bones have no medullary canal, but the diploé or cancellous tissue lying between the outer compact tissue has its spaces filled with a red marrow of the same nature as that in the cancellous tissue of the long bones, wherein the red blood-corpuscles are formed. ‘The large medullary cavity or canal is filled with yellow or fatty marrow. BONES OF THE SKULL. The skull is usually considered in two parts, the cranium and face. The former is composed of nine bones, which will be described in order. The frontal bones (Figs. 15 and 16) are two in number, lying between the orbits, and articulating with one another in the median line. ‘They form the roof of the cephalic part of the brain cavity and the caudal portion of the roof of the nasal chamber. A lateral projection (po, Fig. 16) is known as the postorbital process. Within the frontal bone is a cavity, the frontal sinus (Fig. 18), which contains air and is lined with mucous membrane. It communicates with the nasal cavity. The lateral descending portion of the bone, articulating with the palatine and orbitosphenoid, is the orbital plate of the frontal. In the majority of the Mammalia the frontal is a paired bone, but in man the two portions become anchy- Josed during the fifth or sixth year. Ihe horns of ruminants are outgrowths of these bones. Among the Cervide (deer) horns are usually developed only on the male, and are shed every year. In the Bovide (cattle) the horns are permanent when present. 4 42 ELEMENTS OF MAMMALIAN ANATOMY. The ethmoid (Fig. 18) is a single bone lying ventral to the frontals and nasals. It separates the cranial cavity from the nasal cavity and projects into the latter in the form of two thin scroll-like plates of bone and a median vertical plate. In order to see the relations of this bone, three skulls must be used, one of which should einese thm ot Bes Fic. 15.—DIAGRAM OF THE BONES OF THE MAMMALIAN SKULL VIEWED LATERALLY. 1, 2, 3, etc., indicate the places of exit of the twelve cranial nerves. pmx, Premaxillary; ty, tympanic, 7 and 8 are on periotic; thy, tympano- hyal; shy, stylohyal; ehy, epihyal; chy, cératohyal; bhy, basihyal; thhy, thyrohyal. The cartilage bones are shaded.—(from Flower, after Huxley.) be bisected sagittally, a second should have the roof of the cranial and nasal cavities removed, and the third should be cut transversely on a line- joining the middle of the orbits. The ethmoid is usually visible externally as a small rhomboid plate on the mesal wall of the orbit between the frontal, lachrymal, and palatine bones. It consists of four parts: the paired ethmoturbinals or THE SKELETON. 43 lateral ethmoids (Fig. 18), the mesethmord, and the cribri- form plate. The ethmoturbinals are in the form of scroll-like laminze which project forward from the trans- verse cribriform plate into the nasal cavities. The portion which appears externally in the mesal wall of the orbit —— ; Fic. 16.—DorsaL ASPECT OF THE CAT’s SKULL. ap, Anterior palatine foramen; c, canine tooth; co, coronal suture; jf, for- amina in palatine bone, the lateral one is the posterior palatine and the mesal one is the sphenopalatine; fr, frontal; 2f, infraorbital fora- men; in, interparietal; Jc, lachrymal canal at the anterior border of the lachrymal bone; /d, lambdoidal crest; ml, malar; mx, maxillary; na, nasal; oc, occipital; p, vertical plate of the palatine; po, post- orbital process of the frontal; pm, postorbital process of the malar; par, parietal; px, premaxillary; sg, squamosal part of the temporal; sg, sagittal suture; sp, alisphenoid part of the sphenoid; ¢p, temporal fossa; zg, zygomatic process of the squamosal. is the os planum. In the recent state, the surfaces of these bones within the nasal cavity are covered with a mucous membrane over which the first pair of cranial nerves (olfactory) are distributed. The delicacy of the sense of smell is proportional to the development of the 44 ELEMENTS OF MAMMALIAN ANATOMY. ethmoturbinals. In most orders of animals five scrolls are present, but in Echidna there are six and in some Ungu- lates there are eight, while in adult Primates there are only from one to three, more, however, being present in the embryo. The mesethmoid is the perpendicular plate of bone which, prolonged cephalad by cartilage, separates the nasal cavity into two portions. Caudad it is united to the cribriform plate, dorsally it articulates with the median descending plates of the frontals and the nasals, and ventrelly it articulates with the vomer and pre- sphenoid. The cribriform plate is the caudal portion of the ethmoid (Fig. 18), which, extending transversely between the frontals, separates the cranial cavity from the nasal cavity. Itis pierced by many pinhole foramina for the exit of the olfactory nerve. In Ornithorynchus (duck-bill of Australia) there is a single large foramen in the cribriform plate, as is also the case in birds. The temporal is a paired bone lying at the base and side of the skull. It contains the organs of hearing. It consists of four parts: the squamous or expanded portion (Fig. 16), to which the zygomatic process is attached; the mastoid (Fig. 17), which is the part caudad of the squamosal and dorsal to the bulla; the tympanic, which forms the auditory bulla; and the petrous (Figs. 17 and 18), which contains the internal ear. The squamous portion overlaps the parietal dorsally in a scale-like manner and is limited ventrally by a clearly defined projecting ridge extending above the external auditory meatus as the dorsal border of the zygoma. The zygomatic process extends cephalad to join the zygomatic process of the malar, the two together forming the zygomatic arch, or zygoma, to which the masseter muscle is attached. Ventral of the root of the zygomatic THE SKELETON. A5 process is the glenoid cavity for the articulation of the condyle of the mandible. Immediately caudad of this cavity is the postglenoid process. The mastoid portion of the bone is somewhat triangular in shape, about two centimeters long, and lies caudad of the external meatus. The tympanic portion appears on the base of the skull as the auditory bulla. Its cavity is divided into two unequal chambers by a bony septum rising from the > floor and reaching almost to the roof. The cephalic or true tympanic chamber, sometimes called the middle ear, is the smaller, and has on its lateral wall a horseshoe- shaped prominence known as the tympanic ring, to which the tympanic membrane of the drum of the ear is attached. There are four apertures in the walls of the cephalic tympanic chamber: The meatus auditorius externus, or the external auditory canal; the Eustachian tube, leading from the cephalic dorsal angle of the chamber to the pharynx; the fenestra ovalis and the fenestra rotundum, opening into the internal ear. The caudal or mesal chamber of the bulla is larger than the cephalic, but has no special features worthy of consider- ation. The petrous portion of the temporal bone is not visible on the external surface of the skull, but may be seen by look- ing into the external auditory meatus. It forms the mesal wall of the tympanic cavity. The foramen seen in its dorsal part is the fenestra ovalis. Ina sagittally bisected skull the petrous (Fig. 17) may be recognized by the internal audi- tory meatus entering it. By removing the bulla, a large portion of the petrous bone may be seen from its ventral aspect. A central prominence, the promontory, con- tains the foramen rotundum opening into the base of the cochlea. The apex of the promontory, mesad of the fenestra rotundum, forms the wall of the first whorl 46 ELEMENTS OF MAMMALIAN ANATOMY. of the cochlea. Dorsal to the fenestra rotundum is the fenestra ovalis, opening into the vestibule of the internal ear. In the recent state this opening is closed by a membrane in which is imbedded the foot of the stapes. The cochlea in the interior of the bone may be displayed by cutting away the bony rim of the fenestra rotundum and then chipping off a crust of bone in a line from this foramen to the juncture of the basioccipital and basisphenoid bones. The petrous bone, viewed dorsally in a bisected skull, appears in the floor of the brain cavity ventrad of the tentorium. Its surface is pierced by the internal auditory meatus, which gives passage to the auditory nerve. Close examination reveals a division of the canal into two parts, a ventral for the eighth nerve and a dorsal, the aqueductus Fallopii, for the facial nerve. This aqueduct twists through the petrous laterad, and thence between the petrous, squamosal, and mastoid to the stylomastoid foramen. The parietal bone is paired and joins its fellow in the median line, forming the caudal half of the sagittal suture. Its point of greatest convexity is the parietal eminence. Its cerebral or internal surface presents — slight arborescent grooves which in the recent state sheltered the meningeal artery. The plate of bone pro- jecting obliquely cephalad from the caudal border of the parietal is the tentorzwm, an ossification of the dura mater separating the cerebrum from the cerebellum. The interparietal is a triangular bone situated at the junction of the two parietals and occipital bones. Its sutures are usually obliterated quite early. The occipital (Figs. 16, 17, and 18) is a single bone surrounding the foramen magnum and articulating with the interparietal, parietals, temporals, and sphenoid. In we a -~— . oH. « er Lee “ae & mi a * * Ke ae Be £, - aye thea Fic. 17.—VENTRAL AsPECT OF THE SKULL WITH Tae Lert AuprTory BuLLA REMOVED. ; Jigs ; cs P Dipkencrs: ap, anterior palatine foramina; bs, basisphenci . uditory bulla; bo, basioccipital; ¢, canine tooth; ¢, petrous por ee Pp 1% Seas en, occipital condyle; ea, external “mes eh, opening of the Eustachian tube; fr, fron tal; jm, fo o: num; gc, glenoid cavity; gx, postglenoid process; hm, rea ay cess of the pterygoid; zc, incisor tooth; 7, injraorbital foramen; “ameus; fg, jugular foramen; Id, lambdoidal ridge; mx, max molar tooth; mp, mastoid process; ms, mastoid portion > Brak. fel, ne; pi, pterfgoid ; px, aber gerd of the | te ‘rotundum ; rt, foramen rotundum ; st, stap - mastoid foramen; tc, carotid foramen, o1 h% a 4: . Ss * : ¥ : , SE. | Jee "1 é & ' * = ; a ee oO re de — me a wy re to eee . oe ay oP . ‘ ee ae ; Hh ; ap . ~~. $ -. * j / + ¥ > a oie) ‘ I= a a! ig : “ a ge fe “ — ee a £&, se a ~ Ue es THE SKELETON. A the young kitten it is composed of four parts: the supra- occipital, lying dorsal to the foramen magnum, the two deel A: exoccipitals, lying laterad of it, and a basioccipital, bounding it ventrally. The crescentic elevation on the 48 ELEMENTS OF MAMMALIAN ANATOMY. supraoccipital near its parietal margin is the lambdoidal ridge, to which the cephalohumeral muscle is attached (Fig. 48). The exoccipitals bound the cerebellum laterally and support the occipital condyles, which articulate with the atlas or first vertebra. Immediately caudad of the bulla is the paroccipital process. There are two foramina, one of which, the anterior condyloid, opens ventrally with the jugular foramen adjacent to the bulla, while the other, the posterior condyloid, opens more dorsally at the side of the condyle. The former transmits the twelfth (hypoglossal) cranial nerve, supplying the larynx, hyoid bone, and tongue. The jugular foramen, or foramen lacerum posterius, is at the juncture of the bulla, exoccipital, and basioccipital. The internal jugular vein and the ninth, tenth, and eleventh nerves pass through it. The basiocctpital portion of this bone lies entirely on the ventral aspect of the skull. It articu- lates cephalad with the basisphenoid by a suture which is generally obliterated in cats three or four years old. The sphenoid bone lies in the center of the base of the skull. It is composed of eight parts, corresponding to eight distinct bones in the lower vertebrates: the bast- sphenoid, articulating caudad with the basioccipital; two alisphenoids, extending dorsad from the basisphenoid and articulating caudad with the temporals (Figs. 17 and 18); two pterygoids, projecting ventrally from the basisphenoid and terminating in sharp processes; a presphenoid in the midventral line cephalad of the basisphenoid ; two orbitosphenoids, extending dorso-later- ally from the presphenoid and articulating cephalad with the frontals. In an old cat, the sutures between these eight parts become more or less obliterated. The basi- sphenoid together with the alisphenoids is sometimes THE SKELETON. 49 called the posterior sphenord in distinction to the anterior sphenoid, composed of the presphenoid and_ orbito- sphenoids. TABLE OF THE FORAMINA OF THE SKULE. FORAMINA. ee eee FORAMINA. BONES SURROUNDING THE| STRUCTURES TRAVERSING THE [FORA- MINA. Infraorbital. Anterior palatine. Sphenopalatine. Posterior palatine. Olfactory foramina. Optic. Lacerum anterius, or sphenoidal fis- sure. Rotundum. Ovale. Lacerum medium. Internal auditory meatus. Aqueduct of Fallo- plus. Stylomastoid. Jugular or posterior lacerated. Anterior condyloid. Superior maxillary. Maxillary and pre- maxillary. Palatine. Palatine. Ethmoid. Orbitosphenoid. Alisphenoid and orbitosphenoid. Alisphenoid. Alisphenoid. Petrous and _ basi- sphenoid. Petrous. Petrous, mastoid, and tympanic. Tympanic and mas- toid. Occipital and tem- poral. Exoccipital. Infraorbital nerve of the supe- rior maxillary division of the fifth. Nasopalatine branch of the fifth cranial nerve and nasal artery. Sphenopalatine nerve sphenopalatine artery. Palatine nerve and artery. Olfactory nerve. Optic nerve and meningeal artery. Third, fourth, and sixth cranial nerves and first division of fifth cranial nerve. Second division of fifth cranial nerve. Third division of fifth cranial nerve. Internal carotid artery. and Eighth cranial nerve. Seventh cranial nerve. Seventh cranial nerve. Ninth, tenth, and eleventh cranial nerves and jugular vein. Twelfth cranial nerve. The basisphenoid presents on its dorsal or cerebral surface the sella turcica, or pituitary fossa, which lodges the pituitary body of the brain (Fig. go). The posterior boundary of this fossa is the clinoid plate, and its lateral projections are the posterior clinoid processes. On each side of the basisphenoid there extends dorsally in a : The most cephalic and largest one ELEMENTS OF MAMMALIAN ANATOMY. narrow strip to the parietal the alisphenoid, at the base of which, cephalad of the auditory bulla, are three foramina in a line. “WUNLIOJUS} ‘U7 {VOTDAN} vI[AS “Ys ‘snuis jeprousayds ‘sy ‘uoUvIO; aurjyeyedoueyds ‘fs ‘qeydrooovadns ‘os !prosfhsayd Yd ‘snoajad ‘ad | Areyrxeurosd ‘xd ‘prouaydseid ‘sd f‘ouryeyed ay} ul soreu sopsoysod ‘ud ‘oureped Yd ‘yejeted ‘pd suouivt10y odo ‘do ‘yesveu ‘pu SAIvXvUL Seu SPRUIqany-o[[Pxeur yu ‘[ejoredsay ur ‘dv Ssnyeour Aroyrpne jeusojut Ye {ssao0id proueysysod 73 !snuis [eyuory ‘sf swNuseU ovo; ‘w{ Sauoq jeyuory ‘af {prounyje [eseye_ Jo [eurqanjouryye Jo syjosos “ya “Ya “Ya ‘ssaooad prouro iowiaysod Yo !prouryje jo oyeyd wuosuqiio Jo adpa yno ‘qo ‘prousydsiseq ‘sq ‘ vi[nq Asoyrpne 9g {ajApuoo peyidiooo ‘og {dopey snjonpenbe ‘bp : wauresoy projApuoo 1oL1eyuy “op ‘yey say 30 DY} UL paureUial IWIOA pUL PloWTyjJesoUL oy} yey? OS oULId UeTpour at} JO apts 4Je dt} 0} ATIYSYSs yO sem BY “VINNG GHLOMSIG AVIVLLIOVS V HO AOVAMAS LAD—'sl ‘OM e\tA \ Ss he sphenoidal fissure, or anterior lacerated foramen, which transmits the third, fourth, and sixth cranial nerves supplying the eyeball muscles, and the first Ss THE SKELETON. 51 branch of the fifth nerve. This foramen is between the alisphenoid and the orbitosphenoid. The other two foramina, rotundum and ovale, transmit the second and third divisions of the fifth nerve. The pterygoid portion of the sphenoid is a paired bone (Figs. 17 and 18) lying on either side of the cephalic half of the basisphenoid and the caudal half of the presphenoid. In the adult cat the sutures are some- times obliterated so that this bone appears as a caudal continuation of the palatine. The two pterygoid bones or plates form the descending walls, and, together with the median portion of the sphenoid, the roof of the mesopterygoid fossa, whose cephalic continuation is the posterior nares. From the ventral posterior angle of each projects the hamular process, dorsal of which is seen the small external pterygoid process. Between the bases of the hamular and the external pterygoid processes is the small external pterygoid fossa. The presphenoid tone is the narrow median bone ex- tending from the basisphenoid to the vomer. It contains within it two large sinuses into which project the ventral scrolls of the ethmoturbinal bones. The alisphenoids enter into the formation of the mesal walls of the orbits and are perforated at their bases by the optic foramina, through which pass the optic nerves. @ BONES OF THE FACE. There are seven paired bones in the face and two single ones, making in all sixteen. The premaxillary, with its fellow; extends ventrad and laterad of the anterior nares. These bones bear the six incisor teeth. The anterior palatine or incisor foramina connect the oral cavity with that of the anterior nares. 52 ELEMENTS OF MAMMALIAN ANATOMY. In life, these foramina transmit the naso-palatine nerves. In the Primates, the premaxillary is anchylosed to the maxillary although it arises from a separate center of ossification. The maxillary is a paired bone which meets its fellow in the median line in the roof of the mouth. All its articulations are visible externally except those with the maxilloturbinal, ethmoid, and vomer. Five teeth, a canine, three premolars, and a molar, are present in this bone of the adult cat. The molar is wanting to the young. The several portions of the bone are as follows: the palatine plate, appearing in the roof of the mouth; the nasal process, extending dorso-caudad to the frontal; the malar process, extending ventrad to the orbit to articulate with the malar bone; and the orbital plate, which is the root of the malar process, forming a partial floor to the orbital cavity. The large foramen leading from the orbital cavity through the orbital plate is the infraorbital foramen for the passage of the infraorbital branch of the superior maxillary branch of the fifth nerve. 7 The palatine bone with its fellow helps to form the roof of the oral cavity and the floor of the nasal cavity. It is composed of two plates: one, vertical, forming the lateral walls of the posterior nares and the cephalic part of the walls of the median pterygoid fossa, and a portion of the nasal wall of the orbital cavity; the other, hori- zontal, forming part of the roof of the mouth. The ver- tical plate is pierced by two foramina, the posterior pala- tine and the sphenopalatine, each of which transmits a palatine nerve and artery (Fig. 16). The vomer is a single narrow bone which in the nasal cavity articulates dorsally with the mesethmoid and ventrally with the palatines and the palatine plates of THE SKELETON. a the maxillary, in the median line. This bone, with the mesethmoid and its cartilage, forms the nasal septum, dividing the nasal cavity into two chambers. It is best demonstrated by removing the palatines, when it may be seen extending cephalad from its bifurcated articula- tion with the presphenoid to its articulation with the premaxillaries. The caudal portion of the bone is ex- panded horizontally and articulates with the ventral eth- moturbinals. Its dorsal margin is bifurcated for articu- lation with the mesethmoid. The maxilloturbinal is a paired bone occupying the anterior portion of the nasal cavity (Fig. 18). It is com- posed of a few scrolls which, when the nasal bone is removed, may be seen attached to the maxillary. It consists of a horizontal longitudinal plate, whose lateral border is fixed to the maxillary while the mesal border bifureates into a dorsal curved plate and a ventral scroll. The space between the maxilloturbinal and cephalic por- tion of the lateral ethmoid is the middle nasal meatus. The maxilloturbinal bone in man receives the name of the inferior turbinated, in distinction to the middle and superior turbinated bones, constituting the lateral eth- moid. | _ The nasal bone, joining with its fellow in the median line, forms a large part of the roof of the nasal chamber. » It articulates with the premaxillary, maxillary, and frontal on the surface, and the ethmoid within the nasal chamber. The lachrymal bones are two in number and lie in the cephalic part of the nasal walls of the orbits. Each articulates with the maxillary, frontal, os planum of the ethmoid, and the malar. The bone has about half of the area of the finger-nail. The lachrymal canal is bounded by the lachrymal and the maxilla. This canal, 54 ELEMENTS OF MAMMALIAN ANATOMY. beginning in a vertical groove, the lachrymal groove, car- ries the duct permitting the tears to pass from the eye into the nasal chamber (Fig. 16). The malar bone is paired. It forms the cheek as well as the lateral and cephalic border of the orbit. The arch largely formed by this bone is the zygoma. ‘The process projecting dorsad toward the postorbital process of the frontal bone is the postorbital process of the malar. The masseter muscle originates on the border of the malar. _ cot pr. Fic. 19.—MEsAL oR INNER ASPECT OF THE MANDIBLE. ang, Angle; cndyl, condyle; cor pr, coronoid process; can, canine tooth; imc, incisor teeth; inf. d. fm, inferior dental foramen; zn, inferior notch; mol, molar tooth; prm, premolar teeth; dt, diastema; sm, sur- face of symphysis; wp, superior notch. The mandible or inferior maxillary is the single bone forming the lower jaw (Figs. 17 and 21). It is made up of two halves which are united by an immovable articula- tion or symphysis (Fig. 19) at the chin. Each half con- sists of a horizontal and an ascending ramus. On its alveolar border the horizontal ramus bears three incisor teeth, a canine, two premolars, and a molar tooth. In the caudal part of the oral surface of this ramus is the in- CC a THE SKELETON. 55 ferior dental foramen, which transmits the inferior dental nerve and artery traversing the dental canal extending within the bone to the mental foramen on the lateral sur- face near the base of the canine tooth. The space on the dorsal border between the canine and the first premolar tooth is called the diastema. The ascending ramus or por- tion of the bone caudad of the inferior tooth is marked by six features: (1) the fossa on the outer or lateral surface which gives insertion to the masseter muscle; (2) the angle which is the caudoventral termination of the bone; (3) the inferior notch im- mediately dorsal of the angle; (4) the condyle for the articulation with the glenoid cavity of the temporal; (5) the superior notch dorsal of the condyle; (6) the coronoid process, which is the dorsal termination of the ascend- ing ramus and gives insertion to the temporal muscle. THE HYOID BONES OR HYOID APPARATUS. The hyoid bones consist of two jointed rods, one on either side Fic. 20.—VENTRAL ASPECT oF LARYNX, Hyorp BONES, AND TONGUE. ‘The tongue has been cut transversely near its middle and its mus- cles fixing it to the hyoid have been removed. bh, Basihyal; ch, ceratohyal; cr, cricoid cartilage of the larynx: ev, -epthyal; | ep; epiglottis; lg, cricothyroid ligament; lyh, thyrohyal; rg, rings of cartilage in the trachea; tc, thyroid cartil- age of the larynx ; tm, tym- panohyal; sh, stylohyal. (Figs. 20 and 21), hanging from the temporal bone, and supporting the larynx. Each rod is composed of six parts: the epihyal; the ceratohyal; the tympanohyal; the 56 ELEMENTS OF MAMMALIAN ANATOMY. basihyal; and the thyrohyal. The dorsal end of the thyro- hyal is prolonged by a piece of cartilage, the chondrohyal. The hyoid apparatus varies greatly among mammals. In man it consists of a single bone composed of the body or basihyal, two small cornua representing the cerato- hyals, and two large cornua representing the thyrohyals. The bone is suspended from the skull by ligaments cor- responding to the bony chain in the cat. PRACTICAL QUESTIONS AND SUGGESTIONS. 1. How many more bones present in the cat than in man? 2. In what two parts of the skeleton does the number of bones in the cat exceed those in man? 3. What is a sesamoid bone? 4, Find on a specimen a sesamoid bone and describe it. 5. Draw a lateral aspect of the skull and label all parts 6. What are the paired bones of the cranium? 7. Name the single bones of the face. 8. Draw the caudal aspect of the skull and label all parts. 9. Which bones of the skull derive their names from their location? 10. Which bones of the skull are pierced by more than two foramina? 11. Write a description of the orbital cavity. 12. Which foramina of the skull derive their names from their shape or size? 13. Which foramina derive their names from their location? 14. Which foramina transmit important blood-vessels? 15. Draw figures representing relative shapes and sizes of all foramina of the skull. 16. What bones enter into the formation of the brain cavity? 17. Write about 200 words describing the nasal cavity. 18. Draw a ventro-lateral aspect of the auditory bulla and label all features. 19. Write a description of the auditory bulla and name some mam- mals in which it is absent. 20. Which bones of the skull are composed of more parts in the young than in the adult? 21. Name the principal sutures of the skull. 22. Name the parts of the sphenoid bone in the order of size. 23. Name the bones of the skull visible from the dorsal aspect. 24. Name the bones of the skull visible from the cephalic aspect. 25. What hone of cranium paired in the cat is single in man? THE SKELETON. 57 26. What bone present in face of the cat is wanting as a separate ele- ment in man? 27. Draw lateral aspect of mandible and label all features. 28. Name the bones bearing the teeth. 29. Name the elements of hyoid apparatus in order. 30. Draw a section of the frontal bone showing diploé. 31. Describe the difference between the relative locations of the cranial and facial portions of the skull in cat and man. . 32. Name five membrane bones and five cartilage bones. VERTEBRE. The vertebral column is composed of the following five groups of vertebrez: seven cervical, thirteen thoracic, seven lumbar, three sacral, and caudal varying from four to twenty-six. The following six features are com- mon to all of the vertebre in the first four groups except the atlas: (1) the body of the vertebra (Fig. 22), which forms the floor of the neural canal and articulates with the adjacent vertebree by means of interposed discs of cartilage; (2) the transverse processes, which project laterad from the body or from the walls of the neural canal; (3) a spinous process, which projects dorsad from the roof of the neural canal; (4) the newral arch, com- posed of a pedicle on either side, forming the ventro- lateral walls of the neural canal, and the lamine, extend- ing dorsad from the pedicles to complete the dorsal wall of the neural canal; (5) the zntervertebral notch, which, with the notch of the succeeding vertebra, forms the intervertebral foramen for the exit of a spinal nerve; (6) the articular processes or zygapophyses, two of which pro- ject cephalad and two caudad from each vertebra. The former are called the anterior zygapophyses, and the latter posterior zygapophyses. The first cervical vertebra, or atlas, is characterized by its large horizontally expanded transverse processes, the 5 st CO ELEMENTS OF MAMMALIAN ANATOMY. absence of a spinous process, and its rudimentary body. Its true body in the embryo, becomes united to the axis EtG a2 ms a) SOA Ww ioe hh 4 Ulna | et. ee as the odontoid process. The cephalic margin of the neural arch is prolonged at each side into a process or \ ‘WaueIOy projApuoowidns ‘/ ‘snisuny ey} Jo sApuoo Jowur ‘9 ‘sniaumy oy} jo eJApuoo JayNo ‘¢ ‘eIqe}IOA IequUIN, YWINOF oy} Jo Apoq ‘% ‘sseooid snourds ‘o ‘yeunjoydeos ‘z {orepmoraeu ‘{ {uMUIE}S 94} JO es¥"[T}IVO WIOJ{SUa 10 proydtx ‘x ‘epndvos ay} JO Jepiog [eIqezIeA ‘ga ‘sqii Bulyeoy oY} ‘a ‘stqnd ‘ ‘sassaooid astoasuei} 4] - WINTYOST ayy jo Aysoreqn, ‘gz :yeXyorAyy ‘yz ‘yeXyouedurA, “wz -uInyT oY} JO YOON I{ePOSOTOWS yeo18 ‘os ‘essoy snourdseidns ‘ds ‘essoy reyndeosqns ‘gs ‘yekyoyAys “ys ‘yesourenbs ‘bs :seuoq prouresas ‘s {wi0jseunooseut ‘4 ‘ eyjoyed ‘f ‘ usro0yistd ‘2d ‘ssao0id wouvroejo ‘70 ‘UeteIOF 10}eIN} -qo ‘o {AjIAvd [eYGIO ‘go {1a}WeTDOI} 19}VeI8 “WU /YO}JOU OT}PELOSOIOVS IOSsey ‘s7 StaJojIeunsojue 7 ‘essoy snourdsesyur ‘do ‘wm ‘72 Sumypst ‘s2 ‘ssao0sd JoyWeYOOI} Jesse] ‘yeAyide ‘ya ‘ wItoy -jauns0z0e ‘a {pedo zeieo ‘y9 fafotAvO ‘79 + WIneUBOTeO ‘np ‘pioqno ‘9 ‘prodyiseq ‘gq ‘snjeserysy ‘D ‘Ue YWYSII oy} MoYs 0} se os peyeydeo AT}ySIIs poeynd SI souoq proAy jo urleyo 4eT WT, “LV) HHL dO NOLATHAS AHL AO Loudsy “IVANLWI— I? “SI - Y a0 Woden wAngral p - ' » ‘ t. a! a horid wore al 88 08 bata ‘ : 3 (Sreelo .\o * veiTeoLAD wildest 23 + Bes007Td jon THE SKELETON. 59 articulation with the occipital condyles (Fig. 17) of the skull. The root of this articular process is pierced by a foramen giving passage to the first spinal nerve and the vertebral ar- tery and vein (Fig. 23, fr). From the lateral opening of this foramen (fr) a groove is continued ventrad to the middle of the transverse pro- cess, where it leads into the longi- tudinal vertebrarterial canal com- mon to the first six cervical verte- bre. The vertebral artery and vein course through this canal (Fig. 23). The axis, or second vertebra, is characterized by its odontoid pro- cess, which projects within the at- las, and also by its elongated spi- Fic. 22.—PLAN OF A VER- TEBRA. sp, Spinous process; ar, articular process; ns, transverse process; 1c, neural canal; pd, pedi- cle; /m, lamina; cn, cen- trum or body. nous process, — projects both cephalad and caudad. Fie. 23. Dorsocaupar As: PECT OF ATLAS. ty, Transverse process; nc, neural canal; sp, spinous process; fr, aperture of the transverse part of the ver- tebrarterial canal which enters the atlas at vf; azg, anterior zygapophysis; zg, posterior zygapophysis. The transverse process projects caudad from the body, which is flattened dorsoventrally. This process is pierced at its base by the vertebrarterial canal. The remaining five cervicals are very similar to one another. The seventh has no vertebrar- terial canal. The spinous pro- cesses grow successively longer from -.the third to the seventh (Big. 21). Ihe transverse pro-' cesses of the fourth and fifth are bifurcated, the dorsal branch be- ing called the transverse element and the ventral one the costal element, since it is really the 60 ELEMENTS OF MAMMALIAN ANATOMY. | rudiment ofarib. The transverse process of the fifth ends Fic. 24.—LATERAL ASPECT OF THE AXIS. ar st, Anterior zygapophyses; od pr, odontoid process; n/ sp, neural spine or spinous process; p 2g, posterior zygapophysis; irs pr, transverse process; urt c, vertebrarterial canal. Aa in three branches. The following features are common to all thirteen thoracic vertebre: a spinous process, projecting from the dorsum of the neural arch; two cephalic articular processes or anterior zygapophyses, facing | dorsad or dorsolaterad ; two cau- dal articular processes or posterior zygapophyses, facing ventrad or ventromesad; a body whose transverse diameter is greater i »>fy than the vertical diameter; and a: Sa : transverse processes. There are Fic. 25.— LATEROCAUDAL ‘ ASPECT OF THE SEeconp two half facets on each side of oyna emis the body of every thoracic verte- tr, Tramsverse process; nc, neural canal; ce, facet for bra except the first, eleventh, : tubercle of rib; ar, poste- : : : rior Zygapophysis; 5; spi. twelfth, and” Glaereeeedee eee : nous process; ¢, centrum; head of a rib thus articulates | n, intervertebral notch; e, : ; pedicle; J, lamina. with two vertebre (Fig. 28). 7 The body of the first vertebra | bears on each side a whole facet and a half facet. The THE SKELETON. 61 eleventh, twelfth, and thirteenth bear a whole facet on each side of the body. The transverse processes of the first eleven bear facets for the articulation with the tubercles (Fig. 25) of the ribs. The last three thoracic vertebre are characterized by mammillary processes springing from the dorsolateral portion of the roots of the anterior zygapophyses. Pre. 7526. — Caupar, < ASPECT ‘OF FourtTH LUMBAR VERTEBRA. a, Accessory process; cr, centrum Fic. 27.—Dorsa ASPECT OF THE SACRUM. fl, Floor of the neural canal; jr, dor- or body; pa, pedicle; tr, trans- verse process; s, neural canal; sp, spinous process; zg, the mammil- lary process of the anterior zyga- -pophysis; am, lamina; pz, poste- rior zygapophysis. sal aperture of the intervertebral foramen; /t, lateral mass; pzg, posterior zygapophysis; sp, spi- nous process; sz, auricular surface for articulation with the ilium ; zr, transverse process; zgt, tubercle formed by fusion of the zygapoph- yses; 2g, anterior zygapophysis. The following features are common to all of the lumbar vertebre: a spinous process projecting dorsocephalad (Fig. 26); a transverse process projecting ventrocephalad on either side from the body; aniertor zygapophyses and posterior. zygapophyses. A mammillary process or meta- pophysis is present on the root of the anterior zygapoph- 62 ELEMENTS OF MAMMALIAN ANATOMY. ysis of the first five bones, and-an accessory process or anapophysis occurs on the caudal margin of the wall of the neural arch of all except the last vertebra. The transverse processes increase in length and curvature caudally. The spinous processes increase in length in the same order, and the neural canal likewise enlarges caudally. . The sacrum is a single bone (Fig. 27) formed by the union of three sacral vertebre. The limit of each element is marked by the dorsal and ventral intervertebral fora- mina which furnish passage for the dorsal and ventral branches of the spinal nerves. The two tubercles on either side of each of the three median spinous processes are the result of the fusion of the articular processes. The cephalic portion of the bone presents on its lateral aspect the auricular surfaces for articulation with the ilium. This expansion appears to be a modified transverse process. Prominent transverse processes also project from the caudal angles. The caudal vertebrz vary greatly in number. Accord- ing to Mivart, there are only four in the Manx cat; and according to Jayne, there may be as many as twenty-six in some varieties of the common cat. The transverse processes and zygapophyses become less prominent from the third vertebra to the eighth or ninth, where they are present only as slight ridges. The spinous process is present in the first three, but dwindles to a ridge in the fourth. The first six or seven elements possess a neural arch which more distally loses its roof, making the neural canal a mere groove. The groove becomes fainter dis- tally and finally disappears entirely. The chevron bones are the paired’ ossicles projecting ventrad from the cephalic ends of the bodies of the vertebre, from the second or third to the thirteenth vertebra. In the sixth, THE SKELETON. | 63 seventh, and eighth vertebre the chevron bones unite ventrally in the middle line, forming an arch. The last ten caudal vertebre are scarcely more than cylinders of bone representing the bodies of the vertebre. The number of vertebre in the different species of mammals varies widely. As a rule, there are seven elements in the cervical region. The sea cow (Manatus) has only six cervical vertebre, while the three-toed sloth has nine. The number of thoracico-lumbar varies from sixteen in the orang to thirty-six in the cetacean Del- phinus. The elements composing the sacrum likewise vary from one in the ape, Cercopithecus, to nine in some of the Edentata. The human sacrum is composed of inom ior 1o six vertebra.’ Ilre,same is true of the gorilla, chimpanzee, and orang. The caudal vertebre vary greatly in number in the different forms. In the adult human there are present only four or five vertebra, which form a single bone, the coccyx, while in the embryo © eight segments make up the caudal region. Ossification takes place, however, in only five or six segments. THE STERNUM. The sternum of the cat is composed of eight pieces, called sternebre, which lie in the median line on the ventral side of the chest (Fig. 21). The sternum serves for the attachment of the cartilaginous portions of nine pairs of ribs. The first sternebra (Fig. 28), which ends cephalad in a laterally compressed pointed process, is the manubrium. ‘The six succeeding sternebre form the body or gladiolus; the caudal piece is called the ensiform or xiphoid process. It is terminated by a flat piece of carti- lage. The cartilaginous portion of the first rib articulates with the manubrium near its middle. The ribs from the 64 ELEMENTS OF MAMMALIAN ANATOMY. Fic. 28.—VENTRAL ASPECT OF THE BONES OF THE THORAX.. The num- bers on the vertebral or bony portions of the ribs indicate the names of the ribs. The numbers of the last four ribs are placed just ceph- alad of them. c, Cartilaginous part of first rib; cr, cartilaginous disc between the bodies of the vertebre; en, ensiform process; hd, heads or capitula of ribs; m, manubrium; mr, attachment of twelfth to the eleventh rib; n, free termination of thirteenth rib; 7, attachment of the eleventh to the tenth rib; ¢b, tubercle of first rib; ¢n, transverse process of first thoracic vertebra; v, body of vertebra. THE SKELETON. 65 second to the seventh inclusive are attached at the junctions of the sternebre. The eighth and ninth ribs are attached near together on the caudal end of the seventh sternebra. RIBS. There are thirteen pairs of ribs in the cat. The nine cephalic are called trwe ribs because they articulate dor- - sally with the spinal column and ventrally with the sternum. ‘The other four (Fig. 28) are jalse robs, three of which articulate ventrally with other ribs, while the fourth has no ventral articulation, and is therefore called a floatingrib. Each . rib is composed of two parts, the ver- 1 | | i tebral or bony portion and the sternal or cartilaginous. The following description of the sixth will serve to give a correct idea in general of the anatomy of a rib. Its vertebral portion (Fig. 29) presents _ j four features: a head or capitulum, ig which articulates with the bodies of de the fifth and sixth thoracic vertebre; Poe ie ea ane, a tubercle, which articulates with the ag, Angle; cr, pit for : articulation with transverse process of the sixth thor- Cartiaetnousi oe acic vertebra; a neck, which is the con- tion; f, capitulum ; : 3 : nk, neck; sh, shaft; stricted portion between the capitu- tb, tubercle with fa- jm anameubercle: and the shaft, in- © Cet fer arbeulation : ‘ ° with transverse pro- cluding the portion of the rib between cess. the tubercle and its articulation with the sternal or cartilaginous portion. The bend inthe shaft beyond the tubercle is the angle. ‘The sternal portion of the rib, consisting of cartilage, is sometimes called the cos- 6 666 ELEMENTS OF MAMMALIAN ANATOMY. talrib. Inthe sixth rib the costal portion is about half as long as the vertebral portion. Certain ribs present marked features varying from the sixth. The first rib is stout and flat and has no distinct angle. ‘The articular surface of its head is not divided into two facets, as is the case in all the others except the three caudal ones. The lengths of the ribs increase from the first to the ninth. The last three ribs have no necks and no tubercles for articulation with the transverse processes of the vertebre. The number of ribs varies from nine pairs in the cetacean Hyperoddon to twenty-four in the two-toed sloth (Cholcepus). In most fishes and snakes, ribs are present throughout both the trunk and tail regions, but with the assumption of life on land, and the development of limbs, the vertebrates have suffered a degeneration of the ribs in all parts except the middle portion of the trunk. In the embryo, however, anlage of ribs occurs in all regions of the trunk, but they early coalesce with the vertebre except in the thorax. PRACTICAL QUESTIONS AND SUGGESTIONS. 1. Draw caudal aspect of third thoracic vertebra and label all features. 2. Describe the differences between the first and last thoracic ver- tebre. ) 3. What feature common to all thoracic vertebra not present on any of the other vertebre? 4. Draw the caudal aspect of the fourth cervical vertebra. 5. What feature common to all cervical vertebre except seventh but not present in any other vertebrae? 6. Draw cephalic aspect of atlas and label all features. 7. Compare the third and seventh cervical vertebre. 8. What two features serve to distinguish the lumbar from all other vertebra? 9. Draw the cephalic aspect of the second lumbar vertebra and label all features. 10. Wherein does the seventh lumbar vertebra differ from the first? THE SKELETON. 67 11. How do you distinguish the caudal from the cephalic aspect of any vertebra? 12. Draw ventral aspect of sacrum and label all- features. 13. Give the two features distinguishing the caudal vertebre from all others. ; 14. Note the size and direction of the spinous process throughout the column. . 15. Describe the variation in number of the different groups of ver- tebre in other mammals. 16. Draw lateral aspect of sternum and label all features. 17. Describe the attachment of ribs to sternum. 18. What features common to all the ribs? 19, Name ribs having a tubercle. 20. Draw first rib and label all features. 21. Draw cephalic aspect of ninth rib and label all features. 22. How do you distinguish a false rib from a true rib? 23. What features mark the caudal aspect of a rib? 24. Make a drawing showing the articulation of a rib with the spinal column and label all parts. 25. How do ribs vary as to number in mammals? THE THORACIC LIMB. The thoracic or fore-limb of the cat is composed of a scapula, clavicle, humerus, ulna, radius, seven carpals, five metacarpals, and fourteen phalanges (Fig. 20). The scapula and clavicle form the shoulder girdle. The scapula, commonly called the shoulder-blade (Fig. 30), is not articulated with the bones of the trunk, but is held in position by the serratus magnus, levator angull scapule, and other less important muscles. It articulates with the head of the humerus by the glenoid cavity. It presents three well-marked borders: the cephalic or an- terior, the vertebral, and the axillary adjacent to the vertebre on the side near the axilla or armpit. The outer surface of this bone is divided by a strong spine into two nearly equal fosse, the cephalic of which is the -supraspinous, and the caudal one the infraspinous, fossa. 68 ELEMENTS OF MAMMALIAN ANATOMY. From the lower part of the spine project the acromion and metacromion processes. The subscapular fossa occu- pies the entire inner or mesal surface. Fic. 30.—LATERAL OR OUTER ASPECT OF THE SCAPULA. ac, Acromion process; ax, axillary border; c, coracoid process; gi, glenoid cavity; m, metacromion process; sc, suprascapular notch; sp, spine; sup. fos, supraspinous fossa; vr, vertebral border; n, neck. he A slight constriction between the base of the spine and. the margin of the glenoid cavity is termed the neck. From the cephalic side of the latter the coracoid process curves mesad. A The clavicle is a slender long, imbedded in the mus- Fic. 31.—CaupaL ASPECT OF LEFT Eee besee a le manubrum CLAVICLE. and the coracoid process b, Mesal end; a, lateral end. i (Fig. 258 It does not ar- ticulate with any bone, but is held in place by the cephalohumeral and cleidomastoid muscles (Fig. 48). The shoulder girdle varies somewhat among the Mam- curved bone, about one inch | THE SKELETON. malia. the Carnivora. Primates, Chiroptera, Edentata, and Monotremata are the only orders in which all the species possess clavicles. A third element of the shoulder girdle, known as the cora- coid, is a fully developed bone only in the Monotremata, where it articulates at one end with the scapula, forming part of the glenoid cavity, and at the other end with the presternum. In the other mammals the coracoid is represented by the coracoid process of the scapula, which ossifies from a separatecenter. In many of the lower vertebrates a distinct coracoid is pres- ent. The humerus is the bone of the arm or brachium. It articulates proxi- mally with the glenoid cavity of the scapula (Fig. 21) and distally with the ulna and radius. It consists of three parts: the proximal extremity bearing the head, the middle portion or shaft, and the distal extremity (Fig. 32). The greater and lesser tuberosities separated by the bicipital groove lodging the tendon of the biceps muscle, are the two processes on the proximal ex- tremity. The former is the larger and more cephalic, and serves for the insertion of the supraspinatus muscle 69 The clavicle is never fully developed in any of Fic. 32. — CEPHALIC ASPECT OF RIGHT HUMERUS. bl, Bicipital groove; cr, supracondyloid ridge; cp, capitellum for articulation with the radius; dr, del- toid ridge; ef, “exe ternal condyle; gf, greater tuberosity; at, internal condyle; it, lesser tuberosity ; sp, supracondyloid foramen or entepi- condylar foramen; sy, supinator ridge; tr, trochlea for ar- ticulation with ulna. (Fig. 40). The distal extremity is marked by two im- portant projections, the external and internal condyles. 70 ELEMENTS OF MAMMALIAN ANATOMY. ‘ Extending proximad from the external condyle is the supinator ridge. Fic. 33.—LATERAL OR OUTER As- PECT OF THE RIGHT ULNA. ar, Articular facet for) -radsus;) cr, coronoid process ; gs, greater sig- moid cavity; /s, lesser sigmoid cavity; on, olec- ranon process; st, styloid pro- cess. Proximad of the internal condyle is the supracondyloid foramen transmit- ting the medzannerve and brachial artery (Figs. 72 and 89). The olecranon fossa is the deep cavity on the caudal aspect of the bone, opposite the coronoid fossa. The articular surface of the distal ex- tremity consists of the capitellum, for ar- _ ticulation with the head of the radius, and the trochlea, for articulation with the sigmoid cavity of the ulna. On the cephalic side of the proximal third of the bone is the rough deltozd ridge for the insertion of the deltoid muscle which arises from the shoulder girdle. The ulna is the longest bone of the forearm or antebrachium, and is caudad of theradius. It articulates in the greater sigmoid cavity with the trochlea of the humerus and in the lesser stgmoid cavity with the head of the radius. ‘The distal articulation is with the radius, cuneiform and pisiform (Fig. 21). The olecranon process forms the proximal termination of the bone and serves for the insertion of the triceps muscle. Distad of the sig- moid cavity is a projection known as the coronoid process. The styloid process forms a small projection on the distal extremity of the bone. The radius is the preaxial or cephalic bone of theantebrachium. It articulates proximally with the capitellum of the humerus and the lesser sigmoid cavity : | | sl THE SKELETON. rig of the ulna, and distally with the scapholunar and radius. It bears but two processes, the tubercle and the styloid pro- cess. The tubercle (Fig. 34) is a slight knot near the proximal end on the ulnar side. Proximal from the tubercle is the neck which supports the head bearing a concave crown for articulation with the capitellum of the humerus. The styloid _ process projects from the distal end par- allel with the process of the same name on the ulna. The bones of the antebrachium in many mammals are more or less coal- esced. In the Chiroptera and many of the Ungulates the radius is enlarged at the expense of the ulna, whose proximal third only remains. The primitive Un- gulates of the lower tertiary period pos- sessed a complete ulna as well as radius. The phylogeny of the horse’s limb illus- trates the gradual development of the antebrachium of the Equide (Fig. 35). Fossil remains reveal the fact that mam- mals existed as early as the trzassic pe- riod, when the sedimentary rock forming the triassic strata was laid down. This probably occurred 10,000,000 years ago. According to paleontological investi- gations, the Ungulata arose from the Condylarthra, a group of small five-toed mammals of the lower Eocene, best rep- resented by the typical genus Phenaco- SCE Fic. 34,.— MESAL, OR INNER AS- PECT OF RIGHT RADIUS. fc, Articulatory sur- face for capitel- lum of humerus; hd, head, — the point of the ar- row is on the ar- ticulating surface for the lesser sig- moid cavity; nk, neck; sc, articu- latory surface for scapholunar; st, styloid process; tb, tubercle; wl, facet for ulna. -dus. In this genus and its successor, Hyracother1um, the ulna and radius are well developed and distinct. Orohip- 72 ELEMENTS OF MAMMALIAN ANATOMY. pus, the descendant of Hyracotherium, also shows a dis- tinct radius and ulna, but in the later forms of the horse line the ulna gradually diminishes in size and becomes Been eae Fic. 35.—(See opposite page for explanation.) more and more coalesced with the radius, until in Equus scarcely more than the proximal third remains (Fig. 37). Carpus.—The carpus consists of seven bones arranged : THE SKELETON. rhe in two rows (Fig. 36). Beginning on the pollex side, the scapholunar, cuneiform, and pisiform compose the proxi- Fic. 35.—GENEALOGY OF. THE HORSE. F, Forefoot; H, hindfoot; A, forearm; L, leg; J, Orohippus or Pachyno- lophus; JJ, Mesohippus; JJ, Miohippus; JV, Protohippus; V, Plio- hippus; VJ, Equus; 2, 3, 4, and 5 are the second, third, fourth, and fifth digits respectively; mc, metacarpus; mt, metatarsus; p, pha- langes; u, ulna; 7, radius; ?#, tibia; /, fibula—(After Marsh.) mal row, and the trapezium, trapezoid, magnum, and 74 ELEMENTS OF MAMMALIAN ANATOMY. unciform form the distal row. The scapholunar, easily distinguished because of its large size, articulates with the radius, cuneiform, unciform, magnum, trapezoid, and tra- pezium. The cuneijorm articulates with the ulna, unci- form, pisiform, and scapho- lunar. The pistform is next to the scapholunar in size. It projects prominently laterad from the cuneiform and articulates with the radius, ulna, and cuneiform. The trapezium is the small- est bone ofthecarpus. Itis Fic, 36. A, Dorsal aspect of left manus of cat: a, First phalanx of the pollex; d, second or terminal phalanx; cn, cuneiform; h, head of fourth meta- carpal; m, magnum; mt, metacarpal 4; n, claw; p12, pisiform; s, sesamoid bone; st, scapholunar; td, trapezoid; tm, trapezium; uw, unci- form; 1, 2, and 3, first, second, and third phalanges of the middle digit. B, Generalized type of carpus as found in lower vertebrates: c, Centrale; 2, intermedium or lunare; 7, radiale or scaphoid; ra, radius; m, meta- carpals; u, ulnare or cuneiform; ul, ulna; 1, carpalia 1, or trapezium; 2, carpalia 2, or trapezoid; 3, carpalia 3, or magnum; 4 and 5, car- palia 4 and 5, or unciform. crescentic in shape and articulates with the scapholunar, trapezoid, and first and second metacarpals. The trap- ezoid is almost as small as the trapezium. It is distin- guished by its flatness. It articulates with the scapho- THE SKELETON. vis lunar, magnum, second metacarpal, and trapezium. This bone is not visible on the palmar surface of the wrist. The magnum articulates with the scapholunar, trapezoid, unciform, ee and second, third, and fourth meta- carpals. The wncijorm can be recog- - nized byits wedge shape. It articu- lates with the scapholunar, cunei- form, magnum, and fourth and fifth metacarpals. Each carpal bone de- velops from a single center except the scapholunar, which ee from two centers. The typical cca si the vertebrate carpus is shown in figure 36, B. The pisiform does not be- long to the cartilaginous skeleton, butisasesamoid bone. Inallmam- mals possessing five digits the an- lage of three bones in the proximal row, five bones in the distal row, and a central element occurs in the embryo, but through fusion of ele- ments aless number is presentin 5, 37 Tarwpar As most adults. Thus,in the cat the = PEcr or Lerr Fore- radial d int di a LIMB OF EQuus. e€ and intermedium anda cen- eens cane trale unite to form the scapholunar. metacarpal; m,, fourth : metacarpal; p, phalan- In all forms carpalia 4 and 5 coal- ges; 7, radius: s, sesa- esce to form the unciform. — moid; se, scapula; 1, wiia.; as scaphoid:; [eroumyoreydag ‘(Lp ‘3hq) plorkyjouse}¢ ‘(8p pur Lb ‘S8LJ) Plojsvumours}s (Le ‘Stq) prokyorsy & “(LP ‘8RZ) oAse8Iq ‘(9p ‘Sly) Jojossepy ‘NIDINO ‘UTYS JO [eAOUIOL 94} Joye a[qIsta Ajeijue Jo AyyetWIed ssoy,—"uoIsdy YOON pue peor jo Jade] peroyaodns ‘SHTOSOW HO ATEVI AAILdIaOsSaad nd) Asti ils ‘sossed jr YOM IdA0 sossoo0oid oSIoASURI} oY} Jo qyoodse [eij}UeA oy} SurAdnoso agpsnur pedvys-sjpurds asivy y ‘Teroumnyoreydss oy} Yyveueq gposnur AAvay AOA ®& SI 4] ‘BaYORA} IY} 0} JUVOVI pe oul] UPIpeur oy} Ur o}IUN MO]]P} S}t pue osposnur sity y ‘onsuo} oy} JO Yyonur wi40y sioqy sj] ‘proAyo, Aur uIy} AIDA OY} SULAOUWAI UT No JOU ST MOTE} S}T YJIM 9pOsnur sIq} }ey} UsyR} oq YsNuI s1eD ‘HOT}IOSUT S}T 0} ULSTIO peoiq €v WoO, SULs1aAOD vUIOsAZ OY} JO pesour sossed jy] “SHAVING YY SULTV ‘oSpll [eplopqure’y ‘ouoq prody oy} Jo Apog ‘ONSU0} 9} JO opis ‘ou0q prodyisvg “STC tp, -UBU dt{} JO ssa00i1d prlouo.10g *NOILUASN] "BICO}AVA [BOTAIOO oAyY pue yesiop oeydeo xg | ‘B1IGIIVA [es1op Jo sassaooid snourds pue yoou jo Posey ‘(It ISIE OY} JO osv[VAVD ‘auoqg proAyorAy TL, ‘stsAydmAs otf} IVIU I[QIPULUL JO DOVJAINS [eSOTY ‘asp [eplopqurey] oY} Wor; [NYS oy} Jo oovyang ‘Joo snsuo’y ‘sntuaydg ‘prodyousa}s J “‘snsso[soA Py] 7 ‘(Zp ‘BIy) proAyoruas ‘(gp “Siy) Tesoduray, ‘NIDINO ——¢ — —_ _ — “IO}JISSBPUL pue ‘jeroumyoyeydss ‘pror1Ayjoure}s ‘prloyseuoussys ‘prodyoyAur ‘or1ysestp ‘stje}UoO1yOVdTO90 ‘SOPSNUL Id OY} SUTAOWI Aq O[QISIA 9pVU DSO, —*UOIBOY YOON puv peop] jo JoAv] daoq ey) HHT 4O ni m2} £ ate) ce 1) a 5! Led 1 AiO edt bas gbie itl ont mbit bavorpet 3 - oloenstr 3 jnsozibs bits aie aN 2 ee a - ee fs Sine ve % pane we (aad ys a s a Siatked sok Be biee onleolenne moit10q ce ot oh to. tauin hateetiga 3, igs CREEL: HOD pifos .2ug ah ot aes pga siete ; Bt ay “antl istitiey. neibom bak 3 Didy n Ly a ea ron9g te Ta. bis. oh 4 psd, : GN pile e tim -tagtrottieg See Shnanm 2 alieiaoogesti? hk 15 - eter ot ates the Meat shi t iw .ebiz 3 nt ok pierplon tc as ; 10g © ae O35) fees. tke ybtorgetio: reivoltqydes ' et psi ty jis ae Ai > ek DIDI2Bi roots > Fic. 47.—VENTRAL ASPECT OF THE CEPHALIC HALF OF THE CaT. The superficial muscles have been removed from the left side and the scapula reflected laterad to display the serratus and adjacent muscles. a, Triceps; b, triceps; car, carotid artery; c, c,, and c,, scalene muscles; cph, cephalohumeral; cre, coracobrachialis; dg, digastric; ds, cut end of the digastric; ext, external oblique; jf, inferior constrictor; gh, geniohyoid; h, humerus; 7, scalene; zc, triangularis sterni; zmt, in- ternal oblique; 7; hyoglossus; k, styloglossus; J, rectus lateralis; Jd, latissimus dorsi reflected lateral and much of the reflected portion cut off; Jv, levator.anguli scapule; m, longus colli; man, mandible; mas, masseter ; mh, mylohyoid; md, median ventral line; Nn, fascicl aponeurosis of ‘the external oblique; pe, Ply, PCs, and pc, first, second, third, and fourth parts of the pectoralis muscle; pet, portion of the pectoral muscle of the left side; rct, left rectus abdominalis; sh, sterno- hyoid ; sh,, sternohyoid of the left side.with its middle portion removed : std, sternothyroid; stm, sternomastoid; st, portion of left sterno- mastoid; swb, subscapularis; sps, suprascapularis; tm, teres major; tr, triceps; x, cleidomastoid; 1, 2, 3, 7, 8, and 9, ribs; 5, trachea. — a int oO (or Oo aw) ‘OZIS OUIBS II} qnoqe jo pue Surpaoaid ay} 0} jusoe[pe pue jaered st 4] ‘JOYOIYy} pue Sutpeseid ay} 0} Jey[ered st 1] “WIvIIOJ ay} Jo yoodse oyeydeo s9uUt oy} uO 3pSnUr Uy} BSUCE VW “WOT}IOSUT S}I IvaU sd9or417 -0}99 Y}VoUEq VpIsNuUI jIOYS VW ‘snsuo] 10} -eutdns pur sdao1s}-0}99 oy} Aq pereaood Ayjied st oposnur si, ‘sdao11} oy} Jo red [epnevo JSOUL PUL jSISIL] JY} SI SIL, ‘WIIVIIOJ BY} JO 1OSus}xe yeors oy} SI Iz ‘syzed d014} jo sjsisuoo sdoor1} oy} ue UT ‘gjosnur Surpsoeid ay} 0} peyeydao st jy] ' “snizede13 Jouisysod jo Japi0oq |epnes 24} YUM UT UT st oposnur sIy} jo Jeapioq [epnes oy ‘Ajyepnes Is1Op SNULSST}e] 9} SdepIOAO 7] ‘HOTJIOSUT 0} UISTIO WOT] SUISIIAUOD I[ISNUI UIY} peorq W ‘SNUVNAY ‘yedivorjoum pir yo pus [eurtxoid jo yodse [esiog ‘jedreo -ejoul +puooses jo wimsi0g ‘pus [e}SIP S}L Ieou BUI JO eepINs opeydasosayy ‘ssooo0id wouvlssfo Jo yoodse [e19}e’T ‘AYIA PIOUISIS 91} 07 [eysIp euyn jo yodse [esopy ‘ssoooid uoURIdIIO ‘sdaor3} 94} jo sjied Imoy Joy}O YIM UOWIULOD UT ss9d01d UOUeIDIIO ‘a8pit proyed ‘snisumMy dy} JO sspt4I plojjaq ‘erndeos jo ourds ‘ejndeos jo ourdg “NOILYASNI asaaie ‘gfApuos 0} [eutxoid ‘snsuo] 10jyeutdns uro1y [e}sIp ‘98pl Plo] ‘(6h pure gt -Apuosvidns 19jno Io [v19}e’[ | ‘s8iqz) snsuoy 10zeurdn ‘sniommny " jo pus Teystp jo qoodse [epne) () snovoouy (6F ‘snioumy oy} Jo yoodse [e933] ‘BLyy) snonue sipemorig ‘AUIABS Plous[s oY} Jo pesiop ejndeos oy} Jo Jopioq AreyiIxy | ‘(gp ‘Syy) sdeory-1payy ‘sniouiny Jo yINOF jewrxo1d jo yodse eioye’yT | ‘(gp ‘8h7) sdaorj-0yq 4 ‘guids jo wor10d SUIUDAIZ}UI pue sassao00id UWOMMOINe}OUI pue UOTWMOIDY |*(gF Sh) ees ‘eindvos yo autds | “(gf “Shy) proyepourds ‘eiqa} | (St -I9A d1IdeIOY} Jo sourtds TwInayy | “Ss1yyT) snizede1} 1OLIE}s0g ‘UOISe1 Jap ‘(QF -[Noys ay} Jo vlosey [VsIop-pr | “Syy) snizoeder IoLIeyuy { ‘NIDINO | yoads 1wAaqwT ayy {o sahoT imroysagno— quitja10-4 ay} jo sajsnyy UMA Met "(6h ‘SIy) IOrAeIq snisumy jo yoodse [eroie’]\| syerper idivd 10sua}x7q (6F ‘pure gf ‘sshyy) IOsuUoT ‘g8pl1 proyApuoorvidns .[ev19}e’] | syjetper died 1osueyxy ‘UNIOYSIp snpunjoid 1oxepy oui Aq pozerojiod oie suop -119} 94} UOT}IOSUT IIe} IeON "WISIIO IldY} Iva AIBA VDSBTVOI QpOsnuI 94} JO Sspvol{ OM} OI, SO Sie. P pie oy} BuIyover s10joq oqrun ynq ‘dAIou IeuyN 294} Aq poqyeredas o1e spvol] OM} OT], ‘tuyed of} SUIIOAOD BIOS} 9} OUI SUT -puedx9 o10Joq JSIIM oY} Ivou SNOUIPUs} Souoseq VpOSNUI STy ], ‘JSIIM OY} SuTYyOvII aIojeq Snourpus}; suru10seq QJOSNUI MOIIVU SUOCT & ST SII, "‘poqiiosep }xeu ssoy} Aq PeIdAOD SI IOSNuI sty} JO YON! ‘syed 9A 07UT PeplAIp sil pue ‘we 94} Jo JOSH IOJONppe IB1e] oy} ST 3 ‘“‘sosuvyeyd jo MOL. SPP Sep ae -xoid oy} jo woodse 1emyeg ‘QUOq WIOJISIG ‘elosey Ieuyed ‘jedievovj}our puoses Jo pus jeurxoid jo yoodse srewyedg “StIper ot} JO prryy a[pprut oy} Jo yoodse o1jpeydag “snIoul -ny oy} jo yodse sryeyd -90 JO SpdTY}-OM} [eUMTXOI ‘SHUVNAY “NOILYASNT ‘INIOYISIp snpunjoid soxey oy} wWioIf J9y}O 94} “ySIIM ay} Ivou snsuol siemyed ay} wolf suo ‘spray om} Ag ‘MOUPIOZJO 9} Jo yoodse jesour oy} Woy Jay}O oy} ‘snisumy jo sApuoo [vuseqUT ay} wio1y suo ‘spray omy Ag ‘snioul ny ey} jo aApuoo [eussquy ‘snioul -ny oy} jo eApuoo jeuse}UT *snioul -ny oy} jo ajApuoo jeusozUyT ‘aSR]I}IeD [e1SOO jo spuo [euto}s pue WMNUWIIS ‘NIDIUO ‘(OS “S1iyq) tMnI0 -yiZIp stunyqns 1oxe] 7 ‘slieuyn 1died IoOXxe J “(os ‘BIY) snsuol siiewyeg A “(0S “SIq) syeiper dives Ioxay La | "(QS ‘“ByY) sora} 1oyeUOIg m ” ¢ ‘(LP “8Qq) siyer0qeg yoadsy sauuy 20 yosayy ay, {o sakoT yorisadns "HOISAL WIIeIIO} a4} Ul IOSsUs}xXO jsosIe, IL, ‘Ssnourpus} st SOSMUs Sip JO TET. Testy Sa ot, , ‘syed INO} OUI SOplAIp stim oy} ye. asnu sty} Jo UOpue} eq], ‘jedivo -e}oUI YY Jo yoodse [e197 e’] “WISIP YY ey} Jo Xur| -eyd ysiy jo yodse jes9}e’] ‘sosuvpeyd 94} JO MOI B[ppru jo spus yeurxoid jo yoodse yesioq ‘SnIDUIMY IY} JO sApUoo [e19}v’T ‘snisuimMny jo oJApuoo Jayno JO [e19}e’T ‘snisumMy JO ISpII Poy ‘(6h “S1T) slivujn died 10sue}x]q] ie ‘(6h ‘S1a) I}IsIp TwaTUIUL Iosua}xy 7 aGi2 pue gp ‘sshy) wnI0} -Apuoovidns 19jno JO [e19}e’T | -1Ss1p' STUNUIUIOD Iosua} xX es eee rh Oe ee ‘gjosnur sty} Avdsip 0} poaow - -31 aq ysnur sofeu soto} oY, ‘sdaotq 94} Aq petaA0d SI QJOSNU SIY} JO WOT}JOSUT OT], ‘98PI1 PIO] -Apuooevidns yesour oy} wor; Susie y1ed Joys & pue “yes jo worsod 2]pprar oy} wor; sulsiie jred [esou v ‘snisuny jo pvoy 4} 0} [eIsIp snl Suistie jied jepneos ve ‘syed 321} JO Ss}sIsSUOD spOSNUI SIT, “essoj snourdse1jut 91} SITU I] ‘essoj snourdseidns oy} syy 3 ‘QUITOIOF OY} JO JWIUINS © ‘343 wo1z Apoq oy} puedsns SNUSPU Snjelles oY} pue SIT ‘Teloumny-ojeydso 3} Aq pesaAo0d ssnuI MOIIVU VW ‘snizedel} any yyeoueq Ajo erp -IUIUIT IJOSNUI JO JooYysS pwoiq W “‘SUUVNAY *A}IsoIoqny Sen au} jo oseq ol} 32 snioumy jo yodse [eio}e’] “A}ISOIOqN} Iassoy - 3} JO aseq 94} IesU ISsIOp SNULSST}E] IIA WOWUIOD UT b ‘sdoo11}-Ipot pue sd9011}-0}99 94} WIM wou -WI09 Ut sss00I1d WoUvIDIIO “A}IsoIOqn} 19}eeIs 31} Jo aseq of} Jo yoodse [v10}e’] “‘snismny ai jo AjIsoleqn} 19}¥eII5 “AIAG PIOUS 91} 0} JUSOe[pe tapiog ArelExe oy} Jo Fey aL, ‘Iapiog AreyIxe Jusoe[pe pue endvss oy} jo asue [epnes ‘snisun yy “ern -deos at]} JO Bssoj SHouidee nul “eindeos 343 Jo vessoy snourdseidns “IOUIM Soto], { "(OS *S1yq) Jofeur solay, ihe common duct thus formed is the ductus communis choledochus. When the bile is secreted faster than it is permitted to enter the intestine, it passes backward from the ductus communis choledochus into the cyst. The bile aids in the absorption of the fats by the > villi, and renders the chyme alkaline so that the pan- — creatic juice may act more strongly. The formation of red blood-corpuscles takes place in the liver of the — ORGANS OF DIGESTION. 135 embryo, while in the adult the liver destroys these corpuscles. The chief function of this organ, however, is the formation of glycogen from the sugars and starches eaten and the gradual transformation of this glycogen into sugar as demanded for the nutrition of the body. | Diabetes mellitus is caused by a diseased liver which permits sugar to accumulate in the blood. The pancreas (Fig. 58) is an elongated gland bent at aright angle near its middle. The body of it lies dorsal to the pyloric portion of the stomach, and the head lies close along the concavity of the duodenum. It has two ducts, one of which enters the duodenum in common with the ductus communis choledochus, while the other enters about three centimeters further caudad. The pancreatic juice acts on the starches, proteids, and fats. THE PERITONEUM. The peritoneum (Fig. 59) is the serous sac lining the abdominal cavity and investing most of the organs therein contained. The four portions of the peritoneum are known as the omenta, the mesenteries, parietes, and ligaments. The omenta are three in number, the largest © of which is the great or gastrocolic omentum, stretching caudad from the dorsal abdominal wall and the greater curvature of the stomach, so as to cover the intestine like an apron. It is composed of four layers of peri- toneum forming a closed sac, and bearing more or less fat. ‘Two layers form the ventral wall of the sac attached to the stomach, and two layers are also present in the dorsal wall of the sac which invests the pancreas. The lesser omentum, or gastrohepatic omentum, ex- tends caudad from the liver to the pyloric part of the stomach and duodenum. Its two folds extend from the 136 ELEMENTS OF MAMMALIAN ANATOMY. two sides of the portal fissure, ensheathing the portal vein, hepatic artery, and cystic duct. The gastrosplenic omentum stretches from the cardiac region of the stomach to the spleen, which it embraces, and then proceeds to the diaphragm. The mesenteries are the two layers of peritoneum suspending the intestine from the dorsal abdominal wall. There are four mesenteries: the true mesentery, sus- pending the jejunum and ileum; the mesoduodenum, suspending the duodenum; the mesocolon, suspending the colon; and the mesorectum, suspending the rectum. The parietes or parietal peritoneum is that portion lining the walls of the abdominal cavity. It is a closed sac in the male, but in the female the Fallopian tubes open into it. The ligaments are the layers of the peritoneum sus- pending other organs than parts of the alimentary canal. The jalcijorm ligament extends from the caudal surface of the diaphragm and the abdominal wall, ‘to the surface of the liver, which its line of attachment divides into halves. The round ligament is a fetal relic extending from the umbilicus to the longitudinal fissure on the caudal surface of the liver. A third ligament connects the dorsal border of the liver with the dia- phragm. The broad ligaments of the uterus are the folds of peritoneum which embrace the uterus, the Fallopian tubes, and the ovaries. The ovarzan ligaments are short cords extending from the ends of the uterine cornua to the ovaries. The round ligaments of the uterus pass from the sides of the uterus to the brim of the pelvis. The peritoneum is called a serous membrane because of the colorless serum secreted by it. Other serous membranes are the pericardium of the heart, the pleura lining the thoracic cavity and investing the lungs, and ORGANS OF DIGESTION. L327 the synovial membranes of the joints. Serous mem- branes invest only such cavities as are not exposed to the air. All other cavities are lined by mucous mem- brane. A serous membrane consists of a layer of fibrous connective tissue covered by plate-like endothelial cells. REMARKS ON THE MAMMALIAN DIGESTIVE SYSTEM. The digestive system of mammals varies somewhat among the different groups. In carnivorous animals, as a rule, the alimentary canal is much shorter than in ie ame j HF iN J Fic. 66.—DIAGRAM OF THE STOMACH OF A RUMINANT. a, Dotted line showing the direction of the food in the process of diges- tion; abom, abomasum; du, duodenum; @, esophagus; ps, psalterium ; rt, reticulum. herbivorous. In the wildcat the canal is four times the length of the body, while the canal of the sheep is twenty times as long as the body. In man it is about nine times as long as the distance from the crown of the head to the coccyx. In Ruminants, such as the cow and the sheep, the stomach is very large and divided into four chambers—the rumen or paunch, reticulum, psal- tertum or manyplies, and abomasum (Fig. 66). The rumen and reticulum serve as mere storage cavities, from which the food returns to the mouth for thorough 12 138 ELEMENTS OF MAMMALIAN ANATOMY. mastication, and then passes direct, by means of a groove in the esophagus, into the psalterium, and finally on to the abomasum. ‘The latter is the true stomach, and is provided with gastric glands. In the camels the rumen and reticulum have connected with them pouch- like diverticula for the storage of water. The con- stricted openings of the pouches into the rumen or reticulum may be entirely closed by sphincter muscles. In man and the higher apes there is present an at- tenuated extension of the cecum known as the vermi- form appendix. In the fetus of man it is proportionally longer than in the adult. In the herbivorous mammals, such as the cow and rabbit, the cecum is greatly enlarged, so as to play an important part in digestion. In a few forms, such as the sloths, some Cetacea, and a few Carnivora, the cecum is absent. The lowest mammals, the Monotremata, resemble birds and reptiles in possessing a cloaca into which open the rectum and the urinary and genital ducts. The cloaca opens externally beneath the tail. Salivary and thyroid glands, pancreas, and liver are present in all mammals, but the gall-cyst is absent in Cetacea, the Perissodactyla, Hyracoidea, and a few Rodentia. ‘The liver is usually relatively larger in fat-eating animals. PRACTICAL QUESTIONS AND SUGGESTIONS. 1. Describe the fauces. 2. Describe in detail every feature visible on the dorsal surface of the tongue. 3. Give the number of fangs in each tooth of the permanent set. 4. Give the number of each kind of teeth in the two sets. Draw two aspects of the sectorial tooth. How thick is the enamel of the teeth? Name some mammals which do not have enamel on the teeth. . Name some toothless mammals. . Name some mammals having only one set of teeth. ORGANS OF DIGESTION. 139 10. Give the dental formule for three ungulates. 11. In what animals are some of the teeth greatly enlarged? 12. Do any ruminants have upper incisors? 13. Name the important features of the pharynx. 14. Name every organ in the abdominal cavity, telling with what other organs it is in contact. 15. Describe as much of the peritoneum as you can see in your specimen. 16. Draw the alimentary canal in its natural position, showing all ducts leading into it, and label all parts. 17. How much longer is the small intestine than the large one? 18. On what does the length of the canal in different mammals largely depend? 19. Make a section of a portion of the wall of the stomach and draw what is seen, labeling all parts. 20. Make a section of the small intestine, draw what can be seen by naked eye or simple microscope. 21. About how many villi to each square millimeter? 22. Describe the two channels through which the food passes from the intestines to the heart. 23. Make a somewhat diagrammatic drawing representing that part of the venous system conveying the food from the intestines to the heart. 24. What is the size of the cecum in other mammals than the cat? 25. Give the location, size, and form of the salivary glands 26. Name the lobes of the liver in order of their size. 27. How is the liver held in place? | 28. Draw the pancreas, showing ducts leading to the intestine. 29. Draw the complex stomach characteristic of many ruminants. 30. What is the cloaca and in what mammals is it present? THE VASCULAK. SYSEER. The vascular system is composed of the central forcing muscular organ, the heart; a system of vessels, the arteries, carrying the blood from the ventricles to the lungs and all parts of the body; a system of vessels, the veins, returning the blood to the auricles; and numerous microscopic vessels, the capillaries, connecting the termination of the arteries with the origin of the veins. THE HEART. The location of the heart in the cat may be seen by removing the ventral thoracic wall, but for the study of the parts, the heart of an ox or a sheep will be found more satisfactory. The heart of the cat lies between the lungs (Fig. 80) in the thoracic cavity a little to the left of the median line. The caudal end is the apex, and the cephalic end is the base. The entire organ is in- vested by a tough membrane, the pericardium, which when cut permits the pericardial fluid to run out. All the blood-vessels originate from the dorsocephalic aspect of the heart. It is composed of a right and left half, each of which consists of an auricle and a ventricle. The separation between the two halves is apparent on the ventral surface. The auricles receive the blood from the veins and pass it to the ventricles, which disperse it through the arteries. There is no aperture between the auricles or the ventricles. The aperture between the right auricle and the right ventricle is guarded by the tricuspid 140 THE VASCULAR SYSTEM. IAI valve which prevents the blood from returning into the auricle when the systole or contraction pushes the blood The opening between the into the pulmonary artery. left auricle and left ventricle is guarded by the bicuspid or mitral valve. These valves may be displayed by cut- ting away the caudal half of the ventral wall of the ven- tricles, when the chord _tendinez, delicate tendin- ous cords, will be seen ex- tending from the margins of the translucent membran- ous valves to the columne carnez or muscular projec- tions on the walls of the ventricles. The walls of the auricles are thin in compari- son with the walls of the left ventricle, which are twice as thick as the walls of the right ventricle (Fig. 68). The auricles are very ‘small when not injected, and may by the beginner be cut away with the pericar- dium and surrounding adi- pose tissue. The right auri- cle receives three veins, the precava, postcava, and cor- onary veins, all of which enter its dorsal aspect. Fic. 67.—HEART VIEWED VEN- TRALLY, WITH VENTRAL HALF OF THE AURICLES AND VENTRICLES Cut AWAY AND THE AURICLES DRAWN LATERAD. Partly dia- grammatic. Orifice of the aorta; ao, aorta; aao, arch of the aorta; ap, orifice of the precava; as, orifice of the posteava; lv, left pulmonary veins; lun, left ventricle; mt, mi- tral or bicuspid valve; Ja, left auricle; p, orifice of the pulmon- ary veins; pc, postcava; pre, pre- cava ; ba, orifice of the pulmonary artery; prv, right pulmonary veins; rv, right ventricle and one of the right pulmonary veins; ra, right auricle; rp, right pulmonary artery; tr, tricuspid valve; xp, left pulmonary artery. ~ The por- tion of the auricle into which the above veins open is the sinus venosus. At the dorsal part of the septum which I42 ELEMENTS OF MAMMALIAN ANATOMY. divides this auricle from the adjoining one is an oval depression, the fossa ovalis, where, in the embryo, the two auricles communicated. The left auricle is in con- tact with the right dorsally, and receives three pulmonary veins (Fig. 69). Fic. 68.— VENTRAL ASPECT OF THE Fic. 69—DoORSAL ASPECT OF THE HEART WITH ITS CAUDAL THIRD HEART OF THE CaT. CuT OFF TRANSVERSELY. ao, Aorta ;ap, apex ; as, azygos vein; a, Adipose tissue; bc, brachioceph- bc, brachiocephalic artery; ca, alic artery ; Ja, left auricle; lv, left coronary artery; cv, coronary ventricle; lc, left carotid artery; vein; /, left auricle; lc, left caro- o, ductus arteriosus; pv, pulmon- tid artery; /sb, left subclavian ar-- ary vein; ba, pulmonary artery; pc, precava; psc, postcava; ra, right auricle; rc, right carotid ar- tery; 7s, right subclavian artery ; rv, tight ventricle: sb, left subcla- tery ; f, postcava ; pc, precava; pa, pulmonary artery dividing into its right and left branches; 7a, right auricle; rc, right carotid; rs, right subclavian; v, pulmonary vian- artery; tr, trachea. veins. From the right ventricle arises the pulmonary artery which carries the impure blood to both lungs. Its mouth is guarded by three semilunar valves which prevent the return of the blood. The left ventricle gives origin to only one important vessel, the aorta, which . arches dorsally around the left auricle, and at the apex . THE VASCULAR SYSTEM. 143 of the arch gives off two branches, the brachiocephalic or innominate, and the left subclavian. ‘Three semilunar valves also guard the mouth of the aorta. The arteries of the heart may easily be distinguished from the veins by the fact that the walls of the former are much thicker. THE ARTERIES OF THE TRUNK. The blood-vessels form two systems of circulation; the one known as the pulmonary circulation includes the arteries carrying blood from the right ventricle to the lungs, and the veins returning the blood from the lungs to the left auricle; the other, known as the systemic circulation, includes the arteries conveying the blood from the left ventricle to all parts of the body, and the veins returning the blood to the right auricle. The main artery of the systemic circulation is the aorta, which, beginning in the left ventricle, arches dorsad to the heart and extends along the spinal column to the tail. That portion in the thoracic cavity is termed the thoracic aorta, while that portion in the abdominal cavity is the abdominal aorta. Three semilunar valves guard the mouth of the aorta at its opening from the ventricle, in order that the blood may not be forced back into the heart by the contraction of the muscular coat of the arteries. The branches of the thoracic aorta are as follows: the right and left coronary, arising from the aorta immediately beyond its exit from the ventricle, are distributed to the walls of the heart. From the arch of the aorta arise two large branches: first, the brachiocephalic, giving origin to the right subclavian supplying blood to the arm, and the right and left carotids supplying the head and neck; and, second, the left subclavian, supplying 144 ELEMENTS OF MAMMALIAN ANATOMY. the left arm, brain, and sternum (Fig. 70). Ten pairs of iniercostal arteries supply the intercostal spaces, .muscles of the back, and the spinal cord. Two bronchaal arteries go to the lung tissue. Two to four esophageal arteries are distributed to the ais esophagus. Two or three pairs be.| \) i of /umbar arteries pierce the muscles of the back. The abdominal aorta gives off the following branches: the coeliac axis, the superior mes- enteric, the adrenolumbalis, a pair of renal, a pair of genital, an inferior mesenteric, a pair of iliolumbar, seven or eight pairs of lumbar, a pair of ex- ternal iliacs, a pair of internal iliacs, and a caudal artery (Fig. 70). The celiac axis is a large branch arising just caudad to the diaphragm and gives off the hepatic branch to the liver, pancreas, and duodenum, the Fic. 70.—CuIEF ARTERIES OF THE TRUNK, VENTRAL ASPECT. ar, Arch of the aorta; bc, brachioceph- alic; ce, coeliac axis; cd, caudal; e, coronary: j, gastric; gr, gastric; = | gastroduodenalis; hp, hepatic; it JX location of heart; 2cm, in ed ic, external iliac; 7, internal iliac dw, iliolumbar; «am, inferior mesen- teric: Is, left subclavian; /pl, left pulmonary; m, splenic; o, splenic; 7, night pulmonary ; re, Tenal; sp, oe trunk; sms, superior mesenteric; sm, spermatic or Ovarian; 5, adrenolum- balis; 1, 2, 3, 4, 5, and 6, lumbar arteries. THE VASCULAR SYSTEM. T45 coronary to the stomach, and is continued as the splenic, supplying the stomach and the spleen. The phrenic artery, supplying the diaphragm, sometimes arises from the cceliac axis, but usually from the adrenolumbalis. The superior mesenteric is about the same size as the coeliac axis, and arises within one centimeter caudad. It sends branches to the pancreas and both intestines. The -adrenolumbalis is a small branch on the left side dividing “into the adrenal, phrenic, and muscular. The renal arteries supply the kidneys and usually the suprarenal bodies. The genital arteries are small, and arise from one to two centimeters caudad of the renal arteries. They pass obliquely caudad to the ovaries in the female, and the testes in the male. The inferior mesenteric is almost as large as the superior mesenteric. It is dis- tributed to the large intestine. The pair of 2lzolumbar arteries are small branches supplying the muscles of the iliac region. Four or five pairs of lumbar arteries are given off from the dorsal side of the aorta at regular intervals between the diaphragm and the origin of the external iliac arteries. They supply the muscles of the back and spinal cord. The external iliac arteries are the largest branches of the abdominal aorta and carry blood to the hind-limbs. The umlernal tliac arteries arise more than a centimeter caudad to the external iliacs and furnish blood to the pelvic viscera and the muscles of the innominate region. The caudal artery is the continuation of the aorta beyond the origin of the internal iliacs. It extends into the tail (Fig. 70). ARTERIES OF THE HEAD AND NECK. From the arch of the aorta arise the brachiocephalic and left subclavian, which supply the sternum, neck, 146 ELEMENTS OF MAMMALIAN ANATOMY. head, and anterior extremities with blood. ‘The brachio- cephalic gives off the left carotid and then divides into the right carotid and right subclavian (Fig. 71). Some- times the two carotids arise as a single trunk from the circle Pe Is | Carolia | verlegral Fic. 71.—VENTRAL ASPECT OF THE ARTERIES OF THE HEAD AND NECK The carotids with their branches have been drawn laterad. a, Internal maxillary; ac, anterior cerebellar; ce, median cerebral; crv, posterior cerebral; cp, posterior cerebellar; cx, carotid plexus, many of whose branches reunite into one, cx’, which is cut off; ex, external carotid; em, external maxillary; znc, origin of internal carotid; znc’, union of internal carotid with circle of Willis; za, inferior alveolar; af, infraorbital; 7, optic chiasma; lz, lingual; mn, middle meningeal; ms, muscular; oc, occipital; ol, anterior cerebral; pl, palatine; pa, posterior auricular; s, anterior spinal; th, thyroid; x, hypophysis; 1, 2, 3, 4, 5, and 6, canal in cervical vertebrae. THE VASCULAR SYSTEM. 147 brachiocephalic, which is then continued as the right subclavian. In this case the common trunk of the ca- rotid usually bifurcates within one or two centimeters of its origin, forming the right common carotid and the left common carotid, lying on the respective sides of the trachea beneath the sternomastoid and the sternohyoid muscles. The vagus or tenth cranial nerve and the sympathetic trunk lie in the same sheath with the carotid (Fig. 64). Each carotid artery in the neck region gives off the following branches: a thyrozd to the thyroid cartilage and gland, and a muscular to the muscles of the neck. At the base of the skull, about the middle of the bulla of the temporal bone, a slight enlargement of the vessel is seen, from which arises the very small internal carotid, leading through the foramen lacerum medius to the base of the brain, where it joins the czrcle of Willits. The con- tinuation of the common carotid is now known as the external carotid. This, after giving off a lingual branch - to the tongue, an external maxillary branch to the lower jaw, a post-auricular branch, and a temporal branch, turns to pass along the mesal aspect of the mandible, where it is named the internal maxillary, whose main branches are the inferior alveolar, the middle meningeal supplying the dura mater, several branches to form the carotid plexus, a palatine, sphenopalatine, and wfraor- bital. ‘The latter is the direct continuation of the internal maxillary. It supplies the upper teeth, lower eyelid, parts of the nose, and upper lip. An ophthalmic branch, supplying structures in the orbit, may arise from the carotid plexus or the internal maxillary. The vertebral artery is the first branch given off by either subclavian. It proceeds dorsad and cephalad to the sixth cervical vertebra, whence it extends through 148 ELEMENTS OF MAMMALIAN ANATOMY. the vertebrarterial canal and foramen magnum, to a junction with its fellow in the median line on the ventral aspect of the medulla oblongata. The union of the two vertebral arteries forms the basilar artery, which, after giving off several branches to the medulla and cerebel- lum, divides cephalad of the pons Varolii, forming the circle of Willis around the infundibulum and the optic chiasma. The circle of Willis receives the internal ca- rotid and gives off several arteries to the cerebrum. In man the internal carotid is much larger proportionately than in the cat (Fig. 71). THE ARTERIES OF THE THORACIC LIMB. There is more or less variation in the branching of the arteries in the limbs. No two cats are found exactly alike as to their arteries or veins. The same is true of all other mammals. The subclavian artery, which on the right side springs from, or is merely a continuation of, the brachiocephalic, and on the left side arises from the arch of the aorta, supplies the forelimbs with blood (Figs. 71 and 72). When the subclavian reaches the armpit, it is called the axtlary artery, and its continuation along the humerus is the brachial artery. A continuation of the same artery along the radius is the vadzal artery, furnishing a large part of the blood to the fingers. Four branches arise from the subclavian: the vertebral artery, extending to the brain through the vertebrarterial canal; the internal mammary artery, arising from the ventral side of the subclavian opposite the origin of the vertebral, and extending along the visceral surface of the sternum, and sometimes supplying the pericardium of the heart; the superior intercostal, arising near the THE VASCULAR SYSTEM. T49 vertebral artery and supplying the first and second intercostal spaces, the deep muscles of the back, and the serratus magnus; and the thyroid axis, extend- ing cephalad to supply some muscles of the neck and the lateral aspect of the scapula (Fig. 72). The axillary artery gives origin . to three branches: the anterior thoracic, the long thoracic, and the circumflex. The anterior tho- racic supplies the pectoral mus- cles. The long thoractc is distrib- uted chiefly to the latissimus dorsi. The circumflex artery is almost as large as the continua-. tion of the axillary, which be- yond this point is called the bra- chial. The circumflex, about a centimeter from its origin, after giving off the subscapular, which is distributed mainly to struc- tures in the subscapular fossa, winds around the neck of the Fic. 72.—ARTERIES OF THE FORELIMB. VENTRAL ASPECT. a, Digital artery; an, anastomotica magna; ac, anterior circumflex; az, anterior in- terosseous; ax, axillary; at, anterior thoracic; 6, digital artery; bc, brachio- cephalic; br, brachial; c, dorsal branch of the radial where it passes between the second and third metacarpals to the 42 s¢\f palmar side; cx, circumflex; 7s, superior intercostal; /s, left subclavian; lt, long thoracic; m, branch to extensor muscles; nt, nutrient; p72, pos- terior interosseous; 7, radial; rd, radial recurrent; sf, supracondyloid foramen of the humerus; spr, superior profunda; sb, subscapularis; sp, suprascapularis; st, sternal; th, thyroid axis; ul, ulnar; ur, ulnar recur- rent; vt, vertebral. I50 ELEMENTS OF MAMMALIAN ANATOMY. humerus to its distribution in the triceps and deltoid muscles. The brachial artery, in addition to several muscular branches, gives origin to the anterior circumflex, superior profunda, the nutrient, and anastomotica magna. The anterior circumflex supplies the biceps and head of the humerus. The supertor profunda is distributed to the muscles on the caudal aspect of the humerus. The nutrient artery enters the nutrient foramen of the humerus. The anastomotica magna is the small branch supplying the convexity of the elbow. The brachial artery after passing through the supracondyloid foramen takes the name of radial. The radzal artery, which lies deep beneath the flexor muscles on the caudal aspect of the proximal half of the radius (Fig. 72), becomes superficial along its distal half, where the vessel is covered by skin and fascia only. In the region of the wrist, it curves dorsad and then pierces between the second and third metacarpals to the palmar side, where it sends branches to each of the digits, and forms the palmar arch by anastomosing with the ulnar artery beneath the flexor muscles. In addition to a few small branches, the radial gives off the following: the radial recurrens, supplying the concavity of the elbow; the ulnar recurrens, supplying the convexity of the elbow; the posterior imterosseous, passing caudad between the radius and the ulna to the extensor muscles; the anterizor interosseous, passing along the cephalic side of the inter- osseous membrane; the ulnar, extending beneath the flexor muscles, which it supplies, to the palm, where it anastomoses with the radial to form the palmar arch; and the volar branch, supplying the superficial palmar region. The ulnar and anterior interosseous frequently arise from the same trunk, as shown in the figure. The THE VASCULAR SYSTEM. I5i ulnar artery in the cat is so small that it is frequently not filled by the starch injection, but in man it is larger than the radial. | THE ARTERIES OF THE HIND-LIMB. As in the forelimb, the branching of the arteries in the hind-limb varies considerably in different specimens. The main artery of the leg lies on the ventral or mesal aspect of the femur, passing obliquely to the caudal side of the knee-joint, where it divides into two branches (Fig. 73), one extending along the cephalic, the other along the caudal aspect of the crus. The cat, or at least they caudal half of a cat, should be fastened to the dissectifig tray on its back, the abdominal wall removed, and the viscera pushed laterad to demonstrate the origin of the artery of this limb. As in the forelimb, the main artery in different portions of the leg takes the name of the corresponding region. The external iliac is the largest artery arising from the aorta in the lumbar region. It gives off but one im- portant branch, the profwnda, which, extending caudad, soon gives off a large epigastric artery to the abdominal wall, then smaller branches to the external genital organs, and numerous branches to the muscles on the caudal aspect of the femur. The femoral artery, which is a continuation of the external iliac, extends along the mesal aspect of the femur. In the proximal half of its course it is quite superficial, but the distal portion is covered by the gracilis, sartorius, and semimembranosus muscles. It furnishes four important branches: the anterior femoral, supplying mainly the quadriceps extensor muscle; the superior posterior femoral, supplying the adductor. and & 152 ELEMENTS OF MAMMALIAN ANATOMY. hamstring muscles; the saphenous, accompanying the saphenous nerve and vein to the foot, where it branches and anastomoses with the plantar artery; and the pos- terior injerror femoral, supplying mainly the gastrocne- mius group of muscles (Fig. 52). | The popliteal artery is the continuation of the femoral i Fic. 73.—ARTERIES OF THE RicHt LEG. VENTRAL ASPECT. a, Aorta; at, anterior tibial; aj, anterior femoral; cd, caudal; eg, epigastric ; em, external malleolar; fem, femoral; wm, internal malleolar; 7, ex- ternal iliac; zt, internal iliac; lu, iliolumbar; m, digital; n, digital; o, digital; p, peroneal; pa, profunda; pf, posterior superior femoral; pt, posterior inferior femoral; pn, plantar; pp, popliteal; pt, posterior tibial; ps, saphenous. artery in the popliteal region on the caudal aspect of the knee-joint. One or two articular branches are given | off here to the joint, in addition to the posterior tibial, which supplies the deep muscles of the crus. The anterior trbtal artery is the continuation of the pop- liteal on the lateral cephalic aspect of the tibia, adjacent THE VASCULAR SYSTEM. 153 to the bone. By separating the tibialis anticus and ex- tensor longus digitorum muscles, this artery is well displayed. Near the knee-joint a small branch, the peroneal, is given off, and passes to the dorsal aspect of the foot, where it anas- tomoses with the dorsal branch of the saphenous, forming a superficial arch sending branches to the dig- its. The peroneal is so small that it is frequently not in- jected. Inthe tarsal region two branches, an external malleolar and an wnternal malleolar, are given off. A centimeter or two distal to the latter branch, the main artery passes between the second and third metatar- sals to the deep plantar re- gion, where it receives an anastomosing branch from eee enh So Fic. 74.—CROSS-SECTION OF AR- off branches to the digits. THRY AND VEIN. X 350. V, Vein; A, artery; en, inner coat; ep, epithelium lining the vessels; et, middle or muscular coat of THE VENOUS SYSTEM. vein; ex, muscular coat of artery; : jb, fibro-areolar coat. — (From The veins are the vessels Martin’s “‘ Human Body.’’) returning the blood to the heart. As a rule, veins carry only impure blood, but the pulmonary veins returning blood from the lungs to the left auricle carry pure blood. After death the veins can readily be distinguished from the arteries by the fact that they have much thinner walls than the arteries 13 : % 154 ELEMENTS OF MAMMALIAN ANATOMY. and are usually full of blood, while the arteries are empty (Fig. 74). This is due to the fact that the thick muscular coat of the arteries, by its contraction tends to drive the blood into the veins, whose muscular coat is very thin. The three coats composing the walls of the veins are the epithelial, or tunica intima; the middle, or muscular; and the tunica adventitia, or outer elastic coat of fibro-areolar tissue. The veins of the central ner- vous system and its membranes have no muscular coat. While the only valves in the arteries are found at their ‘ origin from the heart, the veins of the CR limbs, neck, and head possess numerous | # valves. These valves are formed by | _ semilunar folds of the epithelial coat, | strengthened by fibrous tissue (Fig. 75). | The main deep veins of the limbs ac- company the arteries and take the same F1c.75.—VeinCur ames as the arteries. A superficial set OreN. ARROW of veinsis present alsoin the limbs. The SHOWS THE Dri- : : RECTION OF Toe large superficial vein on the lateral aspect Se of the forelimb is the cephalic. The a Sp ene eee superficial vein extending along the valve. mesal aspect of the hind-limb is the saphenous. The Veins of the Trunk, Head, and Neck.—There are two chief venous trunks: the precava, or superior vena cava, and the postcava, or inferior vena cava. Both vessels open into the dorsal aspect of the right ventricle. The veins received by the postcava are thirteen in number. The phrenic veins collect the blood from the diaphragm and empty into the vena cava immediately caudad of the diaphragm. The several hepatic veins collect the blood from the liver, which must be partly dissected THE VASCULAR SYSTEM. away to see their en- trance into the vena cava. ‘The two suprarenal veins return the blood from the suprarenal bodies and two renal veins carry the blood from the kidneys. The left ovarian or sper- matic vein is a tributary to the left renal, but the right ovarian empties directly into the vena cava. zic, common iliac: 226, internal iliac; na, nasal; ov, ovarian or spermatic; pan, posterior auricular; pd, pan- creato-duodenalis; pcv, pre- cava; pst, postcava; prt, por- tal; phrn, phrenic; rn, renal; ste, superficial temporal; st, gastro-epiploica and _ coro- nary; sr, suprarenal; str, ster- nal; sp, gastrosplenic; sm, su- perior mesenteric; sbcl, sub- clavian; tr, transverse; tg, lin- eval - ir verteptal: I 23, 45. - 5, 6, the vertebrarterial canal of the first six cervical verte- bre; w, intercostals; x, supe- rior intercostals, Hn Ne ead Sar NRA os Sadi a! Stee 156 ELEMENTS OF MAMMALIAN ANATOMY. bar muscles empty into the vena cava a centimeter or more cephalad to the large common iliacs. The union of the com- mon wliac veins collecting the blood from the hind-limbs and’ the pelvic region, and the caudal vein, forms the begin- ning of the postcava. The common iliac is formed by the union of the external and internal iliac veins in the pelvis. The former is much the larger of the two. The portal system begins with the veins collecting the blood from the intestines, pancreas, spleen, and stomach, and terminates where the hepatic veins enter the vena cava. The infertor mesenteric vein collects the blood from the large intestine; the superior mesenteric, from the small intestines; the gastrosplenic, from the_ spleen, stomach, and pancreas; the coronary, from the lesser curvature of the stomach; the gastro-eprplorca, from the greater curvature of the stomach; and the pancreato- duodenalis, from the pancreas and duodenum. The last three may empty directly into the portal vein or into one of the three branches first named (Fig. 76). The superror vena cava extends from the union of the brachiocephalic veins to the right auricle. Three im- portant veins empty into the precava: the azygos, col- lecting blood from the intercostal spaces; the sternal, lying on the visceral surface of the sternum; and the vight vertebral, which, with its fellow, collects the blood from the deep muscles and spinal cord in the region of the atlas, and after making a strong anastomosis with the internal jugular vein, descends in company with the vertebral artery through the vertebrarterial canal of the first six cervical vertebre. The left vertebral vein is a tributary of the left brachiocephalic (Fig. 76). The brachiocephalic vein is formed by the union of the subclavian and the external jugular. Sometimes the ver- tebral vein joins also in the union instead of emptying THE VASCULAR SYSTEM. 157 into the precava. The subclavian vein returns the blood from the arm, and accompanies the subclavian artery. The external jugular veins are large vessels lying on either side of the neck beneath the platysma myoides muscle. When the skin is removed, the veins are plainly seen through this very thin muscle. The external jugular is formed ventral to the angle of the mandible by the union of the internal and external maxillary veins. The external maxillaries are united by a large transverse vein. The two tributaries of the external jugular are the cephalic and the internal jugular. ‘The former is the superficial vein on the lateral aspect of the arm, and the latter is the small vein returning blood from the brain. A system of tube-like spaces, called sinuses, whose walls are formed by the dura mater lined with epithelium, takes the place of the large venous trunks within the cranial cavity. These sinuses are usually not filled by a starch injection, but may be filled by a gelatin mass. They cannot be dissected by the beginner. The superior longitudinal sinus extends in the median line beneath the roof of the skull, from the ethmoid region to the tentorium cerebelli, where it bifurcates to form the lateral sinuses, which proceed laterad and ventrad in the substance of the tentorium. The lateral sinus emerges from the ten- torium just caudad to the petrosal bone, where it follows the groove to the jugular foramen. This groove may be seen in a bisected or unroofed skull. The superior petrosal sinus lies in the angle formed by the junction of the tentorium and the petrosal bone, and unites with the lateral sinus just before it reaches the jugular foramen. The inferior petrosal sinus, col- lecting blood from the base of the brain, lies in the groove ventral to the petrosal bone, and unites with the 158 ELEMENTS OF MAMMALIAN. ANATOMY. ~- lateral sinus at the jugular foramen. The union of these sinuses at this foramen forms the znternal jugular vein, which extends deep beneath the muscles of the neck a Wire UL, 5b & any —) ee AMAT ~ nn UuuUL rar sm bes i Er ir Lm spn shin = Lin 1 Jr~il a ANd Fic. 77.—A, VENTRAL VIEW OF HEART AND MAIN ARTERIES IN THE TRUNK OF THE Rappit. 2, ARTERIES OF MAN. ¥, a, Right auricle; ca, left carotid; c ax, celiac axis; 7 m, innominate or brachiocephalic; 2/1, common iliac; 2 m, inferior mesenteric; / r, left renal; rr, right renal; rc, right intercostals; sm, superior mesen- teric; spm, spermatic; sa, sacral; sb, left subclavian. with the carotid artery. It joins the external jugular opposite the shoulder-joint. At the base of the skull the internal jugular gives off a large transverse anastomosing =... °@€=3~S THE VASCULAR SYSTEM. TG) vein to the vertebral, so that the blood from the vein may return partly by the latter vessel. The pulmonary veins convey the pure blood from the lungs to the left auricle. There are three main trunks from each lung. These six veins are arranged in pairs (Fig. 69), constituting a left pair from the left lung; a median pair, composed of one branch from the right and one from the left lung; and a right pair from the right lung. Each pair forms a common trunk before entering the auricle. In order to demonstrate these veins one must remove the heart and lungs from an injected cat, and carefully dissect away the fatty and connective tissues enveloping the vessels. The peripheral connection between the arteries and veins is by means of capillaries, which are microscopic vessels with an extremely thin wall composed of a single layer of epithelial cells. These capillaries are so abun- dant everywhere in the flesh that a needle cannot be inserted without penetrating some. They form a kind of mesh or network, so that every cell may be supplied with oxygen and food and discharge its waste matter. All the blood carried to any portion of the body by the arteries is not returned by the veins, as a considerable amount of the plasma and some of the white corpuscles escape through the thin capillary walls and are returned to the circulation by a system of vessels called lymphatics (Fig. 78). PRACTICAL QUESTIONS AND SUGGESTIONS. 1. What holds the heart in place? 2. Draw the ventral aspect of the heart with the pericardium re- moved and label all features. 3. When the heart is detached from the body, how do you distin- guish the dorsal from the ventral aspect? : 4. How many veins open into each auricle? 5. What arteries lead from each ventricle? 160 ELEMENTS OF MAMMALIAN ANATOMY. 6. After dissecting write a detailed description of the valves of the heart. | 7. Describe the differences in the appearance of the walls of the aorta and vena cava. 8. From your dissection write a description of the features seen in each cavity of the heart. 9. Name the branches of the thoracic aorta in order. 10. Name the branches of the abdominal aorta and tell what organs each supplies. 11. Draw the cceliac axis and its branches throughout their course and label all parts. 12. Show by a drawing the relations of the aorta and venz cave throughout. 13. Make a diagrammatic cross-section of the neck, showing location of arteries and veins. 14. Describe the three routes by which blood may reach the brain and the two routes by which it may be returned to the heart. 15. Name the arteries arising from the arch of the aorta. 16. Draw the inner or mesal aspect of your dissection of the arteries of the thoracic ihmb and label all parts. 17. Draw cross-section of arm at middle of humerus to show location of main artery and vein. 18. Draw cross-section of the middle region of the forearm to show location of chief arteries. 19. Draw outline of the bones of the manus and show relation of ar- teries to bones as seen from palmar aspect. 20. Draw outline of femur and show course of main artery in relation to the bone as seen from mesal aspect. 21. Draw outline of bones of the pes and show relations of the arteries to the bones as seen from the plantar aspect. 22. At what joints in its course is the chief artery of the pelvic limb most superficial? 23. Describe the difference in structure of a vein and an artery. 24. What veins open‘into each auricle of the heart? ~ 25. Name the veins returning the blood from each organ of the ab- dominal cavity. 26. Draw the portal system and label all vessels. 27. Describe the veins returning the blood from the head. 28. Describe the chief blood sinuses in the skull. 29. Where are the valves found in the blood-vessels? 30. If the brachial vein were cut, how could the blood from the manus reach the heart? THE VASCULAR SYSTEM. TOT THE LYMPHATIC SYSTEM. The lymphatics constitute that part of the vascular system which collects the colorless fluid called lymph from the tissues, and the chyle from the small intestine, and conveys them to the external jugular veins. The portion of the lymphatic system originating in the villi of the small intestine and conveying the chyle to the - left thoracic duct is known as the Jacteals. The lymphatic system consists of four parts: (1) the lymphatic spaces between the skin and muscles in all parts of the body, the spaces between the muscles adjacent to the bones, and internal spaces such as those enclosed by the peritoneum and pleura; (2) minute thin-walled vessels beginning by capillary mouths in the spaces just described and leading to larger vessels which empty into the tracheal trunks or thoracic duct; (3) the glands, which vary in size from a mustard-seed to two centimeters in diameter, and are located chiefly on the side of the neck, in the axillary region, at the bifurcation of the trachea; in the inguinal region, lumbar region, and mesentery; (4) the two tracheal trunks and thoracic duct (Fig. 78). One of the largest of the lymphatic spaces is the ereater Cavity of the peritoneum. “Ihe cavity of the lesser peritoneum, a large lymphatic space, may be shown by separating the layers of the great omentum carefully. The cavity of the pleura within the chest is also a large lymphatic space. Numerous small lymph spaces are present in all parts of the body. The lym- phatic capillaries originating in these spaces are invisible to the naked eye, but their union into larger vessels may be demonstrated satisfactorily in a cat just killed, by pulling forward the tongue, and injecting very slowly beneath the skin, on its ventral aspect, five or ten centi- 14 162 ELEMENTS OF MAMMALIAN ANATOMY. meters of a two per cent. solution of Berlin blue in warm water. The lymph glands (Fig. 78) of the cat are not nearly sO numerous as in man. The largest lymph gland is the pancreas Aselli in the mesentery. It is considerably flattened and about two centimeters long. A few other very small lymphatic glands are also present in the mesentery. The two largest lymph glands of the head are just beneath the skin cephalad of the submaxillary gland. On the side of the neck beneath the cephalo- humeral muscle are three large lymph glands at the cephalic border of the scapula. A small axillary gland lies on the caudal side of the axillary vein beneath the scapula. A single popliteal gland is in the popliteal space, an inguinal gland lies on each side of the penis, two or three iliac glands are near the origin of the femoral artery, and a few small lumbar glands lie in the lumbar region of the abdominal cavity. All parts of the body have communication with the lymphatic vessels, which for the most part are so small as to be invisible unless injected, when they are easily recognized by their beaded appearance caused by the numerous valves within them. There are two systems of vessels in the head and extremities—the superficial and the deep. The former accompany mainly the super- ficial veins, and the latter follow the deep veins. On the outer aspect of the thoracic limb just beneath the skin two vessels are present, which flow into the cervical glands. They carry the lymph from the ball of the foot and the skin of the foot and forearm. One or two deep lymph-vessels are found accompanying the brachial vein and artery, which convey the lymph from the bones and muscles of the arm to the axillary gland. In the pelvic limb two or three superficial vessels are THE VASCULAR SYSTEM. 163 present transmitting the lymph from the foot to the popliteal gland, whence two ves- sels proceed to the deep lympha- ticsystem. Thelymph from the bones and muscles of the leg reaches the iliac glands through two or three deep vessels lying near the femoral vein and artery. The inguinal glands receive most of the lymph from the skin of the leg. The lymph from the superfi- cial parts of the head flows largely into the submaxillary glands, while that from the brain, tongue, esophagus, and larynx empties mto “the laryngeal glands. | The lymph of the right fore- limb, right side of the neck and Fic. 78.—VENTRAL ASPECT OF CHIEF LYMPHATIC VESSELS OF THE CaT. a, Axillary gland; as, pancreas Aselli; an, superficial lymphatics from the head; b, bronchial glands receiving lymph from lungs; c, lymphatic trunk; cr, cer- vical glands; cv, laryngeal glands; d, vessel from diaphragm ; e7, external jug- ular vein; 7m, inguinal glands; zl, iliac glands; ju, junction of thoracic duct with tracheal trunk; /, lumbar glands; li, large intestine; /v, lymph-vessel from liver; m, lacteal vessel and glands of mesentery; m, superficial lymphatics from limb; 0, deep lymph-vessels from limb ; on, lymphatics from thoracic wall; ol, vessel from abdominal wall; oc, ves- sels from limb; rec, receptaculum chyli; s, subclavian vein; ¢, lymphatics from skin of leg; tr, il, tracheal trunks; va, lymph trunk from pancreas Aselli to thoracic duct; v, precava; 1 and 2, submaxillary lymph glands. 164 ELEMENTS OF MAMMALIAN ANATOMY. head, and right side of the thoracic wall is received by the right tracheal trunk. The left tracheal trunk re- ceives the lymph from the left side of the head, neck and thoracic wall, and the left forelimb. The thoracic Fic. 79.—PHOTOGRAPH OF LYMPHATIC CAPILLARIES INJECTED WITH BERLIN BLUE. They lie immediately beneath the skin on the outer aspect of the ear. a, Point of injection; the black area is Berlin blue lying in the connec- tive-tissue spaces from which the capillaries arise; m, injection escaped from ruptured vessel. duct receives the lymph from the lungs, heart, all the abdominal viscera, and muscles, and the hind-limbs. With but few exceptions, all the main lymphatic vessels pass through lymphatic glands before reaching one of the THE VASCULAR SYSTEM. 165 three main frunks. In fact, the vessels bringing the lymph to the glands may be said to terminate there. They are called afferent lymphatics. The lymph moves free through the tissue of the gland, and on the opposite side is taken up by the efferent lymphatics. The right and left tracheal trunks lie on their respective sides of the trachea and empty into the external jugular vein just before its junction with the subclavian. The opening is guarded by a valve which prevents the blood from entering the lymphatic trunk. The thoracic duct (Fig. 78) is the largest vessel of the lymphatic system, but is usually invisible unless injected. It extends from the region of the kidneys on the dorsal aspect of the body cavity, along the left side of the spinal column, to its opening into the external jugular vein near where the latter joins the subclavian vein. The caudal end of the thoracic duct is expanded, forming the receptaculum chyli. Numerous valves are present in the duct, and give to it a moniliform appearance. It receives all the lymph from the left abdominal wall, both pelvic extremities, a large part of the thoracic wall, and the thoracic and abdominal viscera. % DUCTLESS GLANDS. The spleen, thyroid gland, thymus gland, and suprarenal bodies are ductless glands whose functions are imper- fectly known. ‘The largest of these is the spleen, which is of a deep red color in a fresh specimen, and lies in the abdominal cavity on the left side caudad to the stomach (Fig. 54). It is about five centimeters long, two centimeters wide, and less than a centimeter thick. It is composed of lymphoid tissue of two forms, sup- ported by connective-tissue trabeculae which are merely 166 ELEMENTS OF MAMMALIAN ANATOMY. prolongations of the enveloping capsule. The two forms of tissue can be seen by cutting the organ trans- versely. The dense lymphoid tissue appears as white spots less than the size of a pin-head. They are the Malpighian corpuscles. Theintervening looser lymphoid tissue forms the greater part of the spleen, and is known as the splenic pulp. The splenic artery, a branch of the cceliac axis, enters the spleen at its hilus and divides into capillaries which terminate in irregular spaces, thus permitting the blood to flow freely through the splenic pulp, whence it is taken up by the capil- laries of the splenic vein leading to the portal vein. In embryonic life the spleen forms blood-corpuscles, but in postnatal life it seems to destroy blood-corpuscles. An animal from which the spleen has been removed may live many years in good health. | The thyroid gland is composed of two parts lying on the lateral aspects of the trachea, just caudad to the larynx. Each part is less than two centimeters long. ~The two parts are sometimes connected by a small isth- mus extending ventrally across the trachea, as in man. An enlargement of this gland in man is called goiter. An animal can live only a short time after the removal of the thyroid unless it is fed thyroids or an extract of thyroid gland. The function of the gland is to supply iodin compounds to the system. The thymus gland is a median structure varying in size according to age. In a cat about one-third grown it is very large, extending cephalad from the heart along the ventral aspect of the trachea three or four centi- meters. As the cat grows older, it gradually dwindles, and is entirely absent in aged specimens. Its function is unknown. It persists throughout life in the lower ver- tebrates. THE VASCULAR SYSTEM. 167 The suprarenal bodies are small, somewhat bean-shaped organs lying cephalad to the kidneys. An animal from which they have been removed can live but a short time. Their functionis not known. They are sometimes spoken of as suprarenal capsules. The above-named ductless glands occur in all mammals in the same relative ocations. The anatomy of the lymphatic system is also exceedingly similar throughout the various orders of mammals. In some animals, espe- cially man, the lymphatic glands are more numerous than in the cat. The tracheal trunks are also wanting in man and a right thoracic duct about two centimeters long is usually present. A failure of the lymphatics to do their work results in dropsy. PRACTICAL QUESTIONS AND SUGGESTIONS. 1. Which of the four parts of the lymphatic system are visible in your specimen? 2. Describe size and number of lymphatic glands in the mesentery. 3. Describe the location of lymph glands present in any other portion of your specimen. 4. How do you distinguish a lymph gland from other glands? . What causes the lymph to flow in one direction only? . What is meant by afferent and efferent lymphatics? . Which kind of blood-corpuscles are found within the lymph-vessels? . From what regions does the thoracic duct receive the lymph? 9. What glands receive the lymph from the thoracic limb? 10. What glands receive the lymph from the pelvic limb? 11. Describe location of spleen, thyroid and thymus glands, and suprarenal capsules by naming the organs with which they are in contact. 12. Draw a cross-section of the spleen and label all features visible. 13. Draw a cross-section of the suprarenal body and label parts. 14. Tell what you know of the functions of the ductless glands. 15. What is a gland? COM OV MN THE RESPIRATORY. SYSTEM Respiration is the process whereby the tissues are sup- plied with oxygen and relieved of their carbon dioxid. In mammals, the special organs of respiration are the lungs, wherein the carbon dioxid is received from the blood, while at the same time the oxygen of the air passes through the thin-walled capillaries to the red blood- corpuscles capable of conveying it to the cells throughout the body. Each cell is composed largely of carbon, hydrogen, oxygen, and nitrogen, and any activity on the part of the cell is the result of the chemical union of some of its elements, whereby several waste products are formed, one of which is the gas, CO, (carbon dioxid). This gas is a poison and therefore must be eliminated. It passes through the thin walls of the capillaries adjacent to every cell, and is transferred through the veins to the heart and thence to the lungs. Here the pulmonary artery divides up into capillaries ramifying over the air sacs (Fig. 82), thus permitting the carbon dioxid to escape into the air sacs. Other waste products resulting from chemical activity within the cells are carried away by the kidneys and sweat glands. The respiratory system consists of the nasal Pakage pharynx, larynx, trachea, and lungs. ‘The air taken in at _ the anterior nares is warmed in passing over the mucous membrane of the turbinated bones, after which it goes on through the posterior nares (Fig. 18) to the pharynx, and thence into the larynx. The larynx is the cartilaginous expansion of the cephalic 168 THE RESPIRATORY SYSTEM. 169 end of the trachea, at the base of the tongue. The basi- hyal bone is attached to the cephalic ventral margin of the larynx and on each side is a thyrohyal bone (Fig. 20). Dorsal to the larynx is the esophagus. By removing carefully the muscles and fibrous tissue from the cartilage the larynx is seen to be composed of five pieces: the epiglottis, thyroid cartilage, two arytenoid cartilages, and the cricoid cartilage (Fig. 20). The epzglotiis is the small triangular cartilage that closes the glottis when food passes into the esophagus (Fig. 55). The thyroid cartilage constitutes the largest part of the larynx. (In man it forms the prominence known as Adam’s apple.) Dorsally the two halves of the thyroid cartilage are separated, each projecting cephalad into a process known as a cornu. ‘The arytenoid cartilages are the two small paired pieces caudad to the thyroid, on the dorsal side. The cricord cartilage forms a complete ring at the caudal end of the larynx (Fig. 20). There are a number of ligaments connecting the various parts of the larynx, the most important of which are the vocal cords. ‘These are of two kinds—true and false. ‘They are best demonstrated by dividing the larynx ‘sagittally. The superior or false vocal cords are the two superior thyro-arytenoid ligaments passing from the arytenoid to the thyroid cartilage, at the base of the epiglottis. The cat is said to use these cords in purring. The inferior or true vocal cords are the inferior thyro- arytenoid ligaments, consisting, as in man, of a fold of mucous membrane on either side, just caudad to the false vocal cords (Fig. 55). The depression on either side between the true and false vocal cords is the ventricle. By means of the muscles attached to the arytenoid and thyroid cartilages, the tenseness of the vocal cords is regulated, and the various pitches of voice produced. 170 ELEMENTS OF MAMMALIAN ANATOMY. The trachea, or windpipe, is the tube leading from the larynx to the lungs (Fig. 54). Its walls are prevented from collapsing by the presence of about forty-five carti- laginous rings which are incomplete dorsally. Before passing into the lungs the trachea bifurcates into a right and a left bronchus. The trachea and bronchi are lined by ciliated columnar epithelium. The cilia project freely labissiimny ¢ S Bs } ey i}. J Sasha 7T Z\U Fic. 80.—DIAGRAMMATIC TRANSVERSE SECTION OF THE CHEST. ao, Aorta; br, bronchus; crd, spinal cord; esoph, esophagus; hd, head of rib; pa, parietal pleura; pc, cavity of the pleura; sp, spinous process; st, sternum; tb, tubercle of rib; tv, transverse process; vp, visceral pleura; ¢, thoracic duct; 7, sympathetic nerve cord; az, azygos vein; trc, trachea; v, pulmonary veins. into the lumen from the columnar walls, and are always waving in such a manner as to carry the secreted mucus lodged thereon toward the mouth, thereby preventing the lungs from becoming clogged with foreign material. Ciliated cells with the cilia in action may be easily demon- strated by scraping very lightly a little mucus from the , posterior part of the roof of the frog’s mouth, and mount- THE RESPIRATORY SYSTEM. ae. Fic. 81.—PHOTOGRAPH OF A LUNG CORROSION OF A PuMA IN MoRPHO- LOGIC MUSEUM OF PRINCETON UNIVERSITY. The specimen was prepared by Mr. Sylvester. The trachea with all its ramifications was injected with white paraffin, and the pulmonary artery with red paraffin, after which the lung substance was eaten away with acid. tr, Trachea; br, bronchus; 6, bronchia; c, bronchiole. The pulmonary artery and its branches are much darker than the air tubes. 172 ELEMENTS OF MAMMALIAN ANATOMY. ing the same in a drop of saliva on a glass slip, which is then to be examined with a microscope magnifying about 300 diameters. The diaphragm of the microscope should be arranged so as to admit but little light. The lungs together with the heart fill up the greater part of the thoracic cavity. Ina cat recently killed the lungs may be expanded by tying a piece of glass tubing on the trachea and blowing into it strongly for a few seconds. Each lung is completely invested by a sac of delicate transparent serous mem- brane called pleura (Fig. 80). Each sac is reflected at the root of the lung, where the blood- vessels and bronchus enter, so as to form a parietal layer lining its half of the thoracic cavity. The median space between the two Fic 82—Tue Teemmnarion~ S2eS 18 called the mediasnaaae OF THE BRONCHIOLE c IN The anterior or ventral medias- Fic. 81. . : tinum contains the heart. The br, Bronchiole; al, alveolus showing about a dozen air dorsal or posterior mediastinum Martin's“ Human Body") contains the esophagus and aorta. Each lung is divided by deep clefts into several lobes. The left lung is composed of two large lobes and a small one. ‘The right lung consists of four unequal lobes. The cephalic end of the lung is the apex and the caudal end, resting against the diaphragm, is the base. The bronchi, as they are continued into the lungs, subdivide into smaller tubes, whose later subdivisions are the bron- chioles. The latter, dividing like the branches of a tree, finally terminate in blind pouches known as infundibula or alveoli, the walls of which are thickly beset with microscopic sac-like evaginations named azr sacs (Figs. THE RESPIRATORY SYSTEM. EAS 81 and 82). ‘The walls of these air sacs are very thin, somewhat like the peritoneum. Over them course numer- ous thin-walled capillaries, so that the carbon dioxid of the blood passes out into the air as the oxygen passes into the blood. Expiration is the process of forcing the air out of the lungs which have been filled by an inspira- tion chiefly effected by depressing the diaphragm and elevating the ribs. The two processes together are _ spoken of as a respiration. PRACTICAL QUESTIONS AND SUGGESTIONS. 1. Of what four elements are the soft parts of the body largely com- posed? 2. What waste gas is formed in every part of the body exercised? 3. Through what three channels do waste materials pass from the blood? 4, Describe the manner in which the oxygen of the air reaches the blood. 5. Write a description of the pharynx. 6. Bisect the larynx in the sagittal plane, make a drawing of the cut aspect, and label all features. 7. How many cartilaginous rings in the trachea and what is their use? 8. Describe as much of the pleura as can be seen in your specimen. 9. Do the right and left bronchi have the same number of main branches ? 10. Why do the air cells seldom become clogged? 11, What muscles are largely used in respiration? 12. Describe the hyoid bone as seen from your dissection. 13. What part of this bone can you feel beneath your mandible? 14, How does the carbon dioxid given off by the cells in the foot reach the lungs? ; 15. What causes the air to enter the lungs? 16. Inflate the lungs of a freshly killed animal by forcing air from your lungs into a glass tube tied into its trachea. 17. After retaining a full inspiration of air as long as possible, expire it through a glass tube into the bottom of a two-liter bottle and insert into the bottle a lighted splinter. 18. Describe the pulmonary circulation. THe? EXCRETORY,: AND REPRODUCG His SYSTEMS: As explained in the last section, a portion of the waste products produced by the activity of the cells of the body is passed off through the lungs, but some other outlet must be provided for the excretions that are not in the form of gases. These liquid excretions, containing various salts and urea, pass off through the kidneys and the glands of the skin. The latter are of two kinds, Shane ge or sweat glands, and sebaceous or oil glands, with ducts opening into the hair follicles near the surface. The sweat glands lie deeper than the sebaceous glands. ‘The former are sub- cutaneous and consist of a more or less coiled tube with a straight duct opening on the surface. They are most abundant on the tip of the nose and the balls of the feet. The sebaceous glands are very numerous all over the body. Both are of microscopic size. A still more important part of the excretory system is the urinary system, consisting of the kidneys, two ureters leading from the kidneys to the bladder, the bladder, and the urethra. The student should note that the kidney is not en- veloped by the peritoneum, like the other abdominal organs, but lies dorsad to it and is encased by a fibrous covering known as the capsule. The hilus is that portion of the concave surface where the renal artery and vein and ureter enter. A median longitudinal section of the kidney will show that the ureter within the kidney 174 THE EXCRETORY AND REPRODUCTIVE SYSTEMS. 175 enlarges, forming the pelvis, into which projects the renal papilla (Fig. 84). transverse section. The substance of the kid- ney is composed of an outer cortical layer, about a half centimeter thick, and an inner medullary substance adjacent to the pelvis, and projecting into the latter in the form of a papilla. In the cortical substance are hundreds of Malpighian bodies, each composed of a ball of capillaries (Fig. 84) enveloped by the invagin- ated enlarged extremity of a tubule which carries away | the urine by a tortuous course to the papilla (Fig. 85). In the Malpighian bodies the water and other mineral substances of the urine are extracted from the blood by means of the epi- thelial cells forming the inner wall of the capsule of Bowman. ‘These urinary products pass through the proximal convoluted tubule and the loop of Henle to the This is better demonstrated in a Fic. 83.—VENTRAL ASPECT OF FE- MALE URINO-GENITAL SYSTEM WITH THE BLADDER PULLED TO ONE SIDE. a, Entrance of the urethra into the vestibule; ao, aorta; bl, bladder; cl, clitoris; cn, cornu or horn of the uterus; jl, Fallopian tube, the left one is cut off; fm, fimbriated extremity of the Fallopian tube; kd, kidney; /, ovarian ligament; ov, ovary; ra, renal artery; 72, renal vein; rc, rectum; wr, ureter; ut, body of the uterus; uth, ure- thra; vc, vena cava; vg, vagina; vs, vestibule. distal convoluted tubule, where they are mingled with the urea extracted from the blood by the columnar epithelial cells of the tubule. From this point the excretions flow Ley 6 ELEMENTS OF MAMMALIAN ANATOMY. into the collecting tube which empties into the pelvis at the papilla. Ina prepared micro- scopic section of the kidney, these Malpighian bodies and uriniferous tubules may be seen with a microscope magnifying about 200 diameters. The ureter is a small tube lead- ing from the pelvis of each kid- ney along the dorsal aspect of the Fic. 84.—MEDIAN LONGITUDINAL SECTION OF A KIDNEY. cor, Cortical substance; hz, hilus; med, me- dullary portion; p, papilla; pl, pelvis; u, pyramids; wr, ureter. abdominal cavity to the dorsal and caudal end of the bladder. The bladder, or urocyst, is the sac for retaining the urine. It lies ventrad to the rectum, a little to the right of the median line, being held in place by the liga- mentum suspensorium, a fold of the peritoneum attached to the mid-ventral line. It is also at- tached by lateral ligaments. Fic. 85.—DIAGRAM OF THE STRUCTURE OF THE KID- NEY BETWEEN THE LINES @ AND CIN Fic. 84. ar, Arteries leading to the Malpighian capsules, only one capsule being shown; b, veins leading from the capillary network about a convoluted tubule as at n; cx, line marking the boundary between the cor- tical and medullary por- tions of the kidney ; cp, cap- sule of Bowman enveloping the bunch of capillaries; d, distal convoluted tubule; hl, Henle’s loop; n, capil- lary network about the tubule; # the bunch of capillaries or Malpighian tuft; wr, portions of urin- iferous tubules emptying into the collecting tubule c; xc, proximal convoluted tubule. On its dorsocaudal aspect, THE EXCRETORY AND REPRODUCTIVE SYSTEMS. 1 oe near where the ureters empty, the urethra originates and passes along the ventral surface of the vagina to the vesti- bule, within which it opens (Fig. 83). Inthe maleit passes directly from the bladder along the ventral surface of the rectum to the root of the penis at the pubic symphysis, and thence on through the corpus spongiosum to the point of the penis. The ureter, bladder, and urethra consist largely of muscular tissue, the lining being formed by mucous membrane. THE FEMALE REPRODUCTIVE SYSTEM. The female reproductive organs are the two ovaries, a pair of Fallopian tubes, a uterus, and a vagina. To demonstrate these, the entire ventral abdominal wall must be removed and the pubic symphysis severed with the bone-cutters. The ovaries are the small yellowish oval bodies about one centimeter long lying just caudad of the kidneys, against the dorsal abdominal wall. From the vicinity of each extends a tube caudad to join its fellow in the median line ventrad to the rectum (Figs. 54 and 83). The cephalic portions of these are the Fallopian tubes, and the larger caudal portions are the cornua of the uterus. The junction of the cornua in the median line forms the body of the uterus. The Fallopian tube is smaller in diameter than the cornu of the uterus, generally more or less contorted, and terminates by a fimbriated expansion or mouth opening freely into the abdominal cavity. The Fallopian tubes and uterus are suspended by the broad ligament, or ligamentum latum, which is a fold of the peritoneum attached to the dorsal abdominal wall. The round ligament, or ligamentum rotundum, also aids in keeping the uterus in place. This appears as a thicken- 15 : Oe 8 ELEMENTS OF MAMMALIAN ANATOMY. ing of the broad ligament when the latter is looked through toward the light. The round ligament extends from about the middle of the horn or cornu of the uterus ventrad of Poupart’s ligament, and through the muscles of the abdominal wall beneath the skin of the inguinal region, where it gradually loses itself. It is exceedingly delicate and thread-like. The vagina extends from the uterus to the vestibule, opening on the surface ventrad to the anus. The small papilla just caudad of the orifice of the urethra on the ventral surface of the vestibule is the clitoris, the homo- logue of a part of the penis in the male. The prominent circular fold of mucous membrane cephalad of the orifice of the urethra represents the hymen, which marks the separation between the vagina and vestibule. This struc- ture may be shown by making a median longitudinal section through the vagina. Bartholin’s glands lie on the lateral aspect of the vestibule, into which their ducts open. Each one is about the size of a small pea. The vagina, uterus, and Fallopian tubes are lined with mucous membrane in which are many glands. The mucous lining is surrounded by a muscular coat especially thick in the uterus. The ovaries are the organs producing the female germ cells or ova which when fertilized are known as the eggs (Figs. 54 and 83). One lies caudad of the kidney on each side and is invested by peritoneum, which should be care- fully dissected away. A microscopically prepared section of the adult ovary magnified about 100 diameters will reveal a number of ova in a more or less mature state. Usually a peripheral ring of very young ova is present, more mature ones are near the center, while one or two quite ripe ova are very near the circumference. As the ova develop, a follicle or sac known as the Graafian THR EXCRETORY AND REPRODUCTIVE SYSTEMS. 179 follicle is formed about them. ‘This is lined with several layers of epithelial cells forming the membrana granulosa. At one side of the follicle the membrana granulosa thickens and envelops the ovum, forming the discus proligerus. The cavity of the follicle is filled with liquor folliculi. When the ovum becomes almost mature, the walls of the follicle have grown peripherad, so as to cause a pin-head protuberance on the surface of the ovary clearly visible to the naked eye. Ina fresh specimen this protuberance may be picked open and the ovum expelled Fic. 86.—SECTION OF Ovary. X 40. sr, Surface of the ovary; gr, Graafian follicle with mature ovum; 0, ovum; c, cavity of the follicle; wn, undeveloped ova; strm, stroma or con- nective elements of the ovary; m, membrana granulosa; d, discus proligerus. on a slide for examination with the microscope. The ovum is scarcely visible to the unaided eye. The human ovum is still smaller. : The ova of all mammals, except the Ornithodelphia (Monotremata), are very small. When the ovum becomes mature, the protruding wall of the follicle bursts, per- mitting its contents to be received by the expanded end of the Fallopian tube, whence it passes to the uterus. If the male element, the spermatozoon, enters the ovum, the latter is soon enveloped by a growth of mucous mem- brane and retained in the uterus for development. Ripe 180 ELEMENTS OF MAMMALIAN ANATOMY. ova occur near the close of the first year of the cat’s life and new ones probably continue to mature during the next ten years. The discharge of the ova from the ovary is accompanied by a constitutional disturbance, during which an extra amount of blood is sent to the sexual organs, and the sexual appetite becomes very marked. In the human species this disturbance occurs about every twenty-eight days. Mature ova occur in the human ovary between the thirteenth and forty-eighth years. The mammary glands of the adult female cat reach their full development when it gives birth to young. They may be seen by carefully removing the skin from the ventral aspect of the body, when they will appear somewhat like a thin layer of adipose tissue extending from near the axilla to the pubic symphysis. There are four teats or nipples on each side. In some mammals the nipples are less numerous and confined either to the thoracic or inguinal region. In the elephant, Chiroptera, and Primates there are but two nipples, and they are thoracic. In most Ungulates the nipples are inguinal. THE MALE REPRODUCTIVE SYSTEM. The organs of generation in the male consist of the testes, the ducts leading from the testes to the urethra, the prostate gland, Cowper's gland, and the pents. The testes are two in number, contained in a pouch of integument called the scrotum, which hangs beneath the anus. Internally the scrotum is divided into two cham- bers. By dissecting away the adipose tissue covering the spermatic cord in the inguinal region (Fig. 51) it may be seen that the cord and the testes are enveloped by a tough sheath. This is composed of cremasteric jascia derived from the aponeurosis of the external ob- THE EXCRETORY AND REPRODUCTIVE SYSTEMS. lique muscle, and of the tunica vaginalis. between these two coats is a thin layer of fibers forming the levator scroti muscle. The tunica vaginalis is com- posed of three layers, the outer of which is the fascia propria, derived from the transversalis fascia. The other two are derived from the peritoneum. During fetal life the testes lie in the abdominal cavity, and when they descend into the scrotum about the time of birth, a double layer of peritoneum is pushed down before them through the in- guinal canal, forming a di- verticulum whose blind end lies within the scrotum, while the constricted por- tion forms a channel for the vas deferens, spermatic nerve, and vessels. These three structures form the spermatic cord (Fig. 51). The fascia propria (tunica vaginalis communis) is in- separably united with the adjacent parietal layer of the peritoneum. The vis- ceral layer of peritoneum is quite delicate and trans- I8t On the testis Fic. 87.—VENTRAL ASPECT OF THE MaLE REPRODUCTIVE ORGANS. cr, One of the criura of the penis: ep, epididymis revealed by cut- ting and reflecting vg, a piece of the tunica vaginalis and albu- ginea; et, external abdominal ring; 2, internal abdominal ring; in, inguinal canal; g, glans penis; gd, Cowper’s glands; pe, penis; pr, prostate gland; rc, rectum; t, testis‘ from which the tough sheath composed of the levator scroti muscle and cremaster fascia has been removed, leaving it en- veloped by the tunica vaginalis; ts, testicle from which a portion of the tunica vaginalis has been reflected; uth, urethra; ur, ure- ters; vd, spermatic cord; vdd, vas deferens within the abdominal cavity; vg, tunica vaginalis re- flected; vg,, tunica vaginalis; v, >Spermatic vein. oa 182 ELEMENTS OF MAMMALIAN ANATOMY. parent and lies close to the testis. Immediately sur- rounding the latter is a dense capsule, the tunica albu- ginea, sending septa into the interior. Within the tunica vaginalis is the tunica albuginea, closely investing the testicle, and adjacent to the epididymis penetrating the. substance of the gland, forming a septum known as the mediastinum testis or corpus Highmorianum (Fig. 87). The testis is about 14 centimeters long by 1 centimeter thick. On its dorsal surface lies the epididymis, an elongated body composed of an enlarged extremity, the globus major, and an attenuated portion, the globus minor. The main portion of a testicle is composed of many minute coiled tubules, tubult seminifert, which unite into a few tubules near the surface of the testis beneath the globus major, into which they ex- tend. These tubules are the vasa “% efferentia. ‘The epididymis is com- Fic, 88.— Spermatozoa posed of a single greatly convoluted OF OO CHEM CEMS. tubule of which the vas deferens is h, Head; ¢, tail. a continuation. The latter pro- ceeds cephalad to the external ab- -dominal ring, which it enters to traverse the inguinal canal into the abdominal cavity. It then curves caudad and enters the urethra on its dorsal aspect in the neste of the prostate gland. The inguinal canal begins with the external abdominal ring, which is an opening in the tendon of the external oblique muscle, and ends with the internal abdominal ring, which is an opening in the fascia of the transver- salis muscle (Fig. 51). By accident, a fold of the small intestine sometimes descends through the inguinal canal, which condition is known as hernia or rupture. THE EXCRETORY AND REPRODUCTIVE SYSTEMS. 183 The penis is a cylindrical pointed body about three centimeters long when in repose. It is composed of two kinds of tissues arranged in three bundles. The corpus spongiosum is the median ventral bundle, extending - throughout the length of the organ, and at the end forms the glans or head. ‘The two dorsal lateral bundles are the corpora cavernosa. ‘They form the greater part of the penis proximad of the glans, and by diverging - somewhat before their attachment on either side to the pubis and ischium form the crura. ‘The penis is sus- pended from the wall of the abdomen by a fold of in- tegument inserted at the base of the glans, and forming the prepuce. The latter is a free projection of skin covering the glans. In the midst of the penis is a small bone. The penis is the organ of copulation, and is com- posed of a spongy mass of elastic and muscular fibers richly supplied with highly distensible blood-vessels which when filled render the organ erect. The prostate gland surrounds the urethra dorsally and laterally about two or three centimeters from the bladder. This gland secretes a milky fluid which is poured into the urethra through many ducts, during copulation, and serves as a medium for the spermatozoa (Fig. 87). Cowper’s glands are two in number, about the size of a pea, and lie in the angles formed by the urethra and the crura of the corpora cavernosa. These glands secrete a viscid fluid of unknown function. One duct from each gland opens into the urethra. 184 ELEMENTS OF MAMMALIAN ANATOMY. REMARKS ON THE MAMMALIAN UROGENITAL SYSTEM. The urogenital system is subject to some variations in the different orders of Mammalia. In the Ornithodelphia, the mammary glands are devoid of teats and the oviducts corresponding to the Fallopian tubes and horns of the uterus do not unite in the median line to form the body of the uterus, but unite with the urethra, forming the urogenital canal. The latter opens into an enlarged terminal portion of the rectum, called the cloaca. The ureters also open directly into the cloaca, so that there is but one external opening for the genital and excretory products. In the above features the Monotremes resem- ble the Amphibia and reptiles. All mammals are vivip- arous except the Monotremata, which are oviparous, laying eggs as large as those of the robin. The Orni- thorhynchus incubates its eggs in an underground nest, while the Echidna carries hers in a temporary abdominal pouch. The Marsupialia bring forth their young in a very immature condition. They are then carried for several months in an abdominal integumentary pouch, the marsupium, within which are the nipples. In the Mono- tremata, Cetacea, Sirenia, and elephant the testes do not descend into a scrotum, but are retained in the primitive location within the abdomen. In Primates and some Edentates, the uterus is merely a pear-shaped body without any cornua, the Fallopian tubes leading directly into the body of the uterus. In the ox, bears, seals, and cetaceans the kidneys are distinctly lobulated. Internal evidence of lobulation is presented in most mammals by the renal papilla. In the embryo the kidneys of all mammals are lobulated. THE EXCRETORY AND REPRODUCTIVE SYSTEMS. 185 PRACTICAL QUESTIONS AND SUGGESTIONS. 1. What other waste products besides CO, result from the chemical action in the tissues of the body? 2. Write a description of all parts of the urinary system visible in your dissection. 3. Bisect a kidney longitudinally in the horizontal plane, draw the cut surface, and label all features. 4. Explain the parts of a uriniferous tubule. 5. Wherein does the male urinary system differ from the female? 6. Make a drawing of the Fallopian tubes and uterus and label all parts. 7. Describe location, size, external appearance, etc., of the ovary as seen in your specimen. 8. How are the female reproductive organs held in place? 9. Can you distinguish externally the termination of the uterus and the beginning of the vagina? 10. Are there any eggs protruding from the ovary or any cavities from which eggs have been recently discharged? 11. Describe a Graafian follicle. 12. What must be added to the ovum to produce another animal? 13. Name the parts of the male reproductive system present in your specimen and locate them. 14. Describe the course of the spermatozoon from the testis to the exterior. 15. Do all mammals nourish their young in the same manner? 16. What mammals incubate their eggs externally? 16 THE NERVOUS SYSTEM. The nervous elements of the cat form three systems, known as the central, peripheral, and sympathetic. The central nervous system includes the brain and spinal cord. The peripheral system includes the twelve pairs of nerves emanating from the brain and the forty pairs of nerves emanating from the spinal cord to supply the extremities and trunk. The sympathetic system is composed of two ganglionated nerve cords extending throughout the trunk within the body cavity, one on either side of the vertebral column, and their various branches to all the viscera, blood-vessels, etc., of the body (Figs. 91 and 92). THE BRAIN. The central nervous system is known as the cerebro- spinal axis. It is composed of the brain and spinal cord. The brain lies within the cranial cavity and is protected by three membranes called the meninges. ‘These may be demonstrated by cutting away the roof of the skull with the bone forceps. The dura mater is the tough fibrous membrane lining the interior of the skull. It dips down between the two halves of the cerebrum, forming the jalx cerebrt. Between the cerebrum and cerebellum in the cat it is ossified, thus forming the bony shelf or ten- torium cerebelli (Fig. 18). The dura mater adheres closely to the inner surface of the cranial cavity, forming the internal periosteum. The second membrane of the brain is the arachnoid, Between the dura mater and the 186 THE NERVOUS SYSTEM. 187 arachnoid is the subdural space, containing a fluid having the nature of lymph. The arachnoid is a very delicate membrane which does not dip down into the sulci between the convolutions of the brain, as is the case with the pia mater, but passes across these depressions, where it may be easily demonstrated (Fig. 100). The subarachnoidal space lies between the arachnoid and pia mater. The pza mater is the delicate vascular membrane following so closely the convolutions and sulci of the brain that it becomes apparent only when lifted carefully by the forceps. In order to study the brain satisfactorily each student should have a specimen hardened according to directions in the section on technique, and also should be permitted to examine a series of sections cut transversely about a centimeter thick. ‘These sections may be mounted for permanent use in pasteur dishes, according to the method described in the “ Journal of Applied Microscopy,’’ Octo- ber, 1902. ‘The brain of a calf or sheep serves the learner’s purpose better than that of a cat, as the parts are larger, and they are also easier to procure. An additional ad- vantage is also found in the fact that there is some difference between the brains of the cat and calf, and the student must therefore rely more on his own observa- tions. External Features.—The brain is composed of five parts: the medulla oblongata, or myelencephalon; the pons Varolii and cerebellum, forming the metencephalon; the corpora quadrigemina and crura cerebri, composing the mesencephalon; the diencephalon, including the optic thalami and other parts bounding the third ventricle; and the telencephalon, or cerebral hemispheres. The medulla oblongata, sometimes called the bulb or stem of the brain, is the expansion of the spinal cord as it 188 ELEMENTS OF MAMMALIAN ANATOMY. passes through the foramen magnum. ‘The pons Varolii is the bridge of transverse fibers seen on the ventral aspect of the brain just cephalad of the medulla (Fig. 94). The cerebellum or little brain lies on the dorsal side of the medulla and is partly covered by the caudal part of the cerebrum. ‘The mesencephalon is not visible exter- nally on the dorsal aspect, but may be seen immediately cephalad of the cerebellum by cutting away the cerebrum (Fig. 98). The diencephalon is visible externally only on the ventral aspect of the uncut brain, where it forms the floor of the third ventricle. _It may be viewed as a whole if the dorsal half of the cerebrum including the corpus callosum is cut away. The telencephalon is com- posed of the two large hemispheres partially surrounding the diencephalon and mesencephalon. The brain is composed of two kinds of matter, white and gray. The former is constructed for the most part of fibers, while the latter is formed largely of cells. The outer or cortical portion of the cerebrum and cerebellum is a layer of gray matter less than a half centimeter thick, and is disposed in folds called gyri or convolutions with intervening depressions termed sulci, the more im- portant of which are called fissures. The four different portions of the cerebrum are known as frontal, parietal, occipital, and temporal lobes, which occupy the respective regions of the cranial cavity. The frontal and parietal lobes are separated by the cruczal fissure, extending transversely between them. The ol- factory lobe (usually torn off in removing the brain from the skull) projects from the cephalic portion of the frontal lobe. The parietal lobe is marked by three gyri, named according to location gyrus marginalis, gyrus suprasylvius, and gyrus ectosylvius (Figs. 89 and go). The caudal portions of the gyri marginalis and supra- THE NERVOUS SYSTEM. 189 sylvius constitute a portion of the occipital lobe. two gyri are separated by the lateral sulcus. These The supra- sylvian sulcus extends between the gyrus suprasylvius . and the gyrus ectosylvius. separates the gyrus marginalis from the gyrus fornicatus on the mesal aspect of the parie- tal and occipital lobes. There are no definite sulci or fissures separating the parietal, occipi- tal, and temporal lobes. The postrhinal fissure, extending caudad from the fissure of Syl- vius, divides the temporal lobe into two portions on the ven- tral aspect. The ventral surface (Fig. 90) of the brain also presents im- portant features which should be noted by the student before investigating the isiternal structure. The anterior pyra- mids, two indistinctly differ- entiated bundles of fibers, oc- cupy the mesoventral region of the medulla, and cephalad of the pons help form the crura cerebrt. Laterad of each pyra- mid is the olivary projection. A broad band of transverse fibers appearing just caudad The splenial sulcus (Fig. 92) Fic. 89.—DorsaL, ASPECT OF THE BRAIN. a, Gyrus marginalis; ac, white matter of the cord; ad, gray matter of the cord; 6, gyrus suprasylvius; c, gyrus ectosyl- vius; cr, crucial fissure; ce, lat- eral lobe of cerebellum; d, lat- eral sulcus; e, suprasylvian sulcus; lg, great longitudinal fissure; md, medulla oblon- gata; n, first spinal nerve; ol, olfactory lobe; , posterior pyramids; sp, spinal cord; v, vermis of cerebellum. of the pons Varolti and laterad of the anterior pyramids is the corpus trapezordeum. The pons Varolw is itself composed of a band of Fic. 90.—VENTRAL ASPECT OF THE BRAIN. 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, The cranial nerves; a, ophthalmic branch of the trigeminal nerve; an, anterior pyramids; at, anterior horn of gray matter; b, superior maxillary branch of the trigeminal nerve; lla, eleventh cranial nerve with roots from the spinal cord; c, mandib- ular branch of the trigeminal nerve; ca, corpus albicans; cb, cere- bellum ; cc, canalis centralis; cn, cornea; ct, cut surface of spinal cord; ex, external rectus muscle; cr, crus cerebri; g, Gasserian ganglion of the trigeminal nerve; hl, pyriform lobe; 7m, opening into the tuber cinereum revealed by removal of the infundibulum and pituitary body; 72, internal rectus; 720, inferior oblique; 77, inferior rectus; n, and n,, first and second spinal nerves; ol, olfactory lobe; of, optic com- missure; ot, optic tract; p, posterior, horn of gray matter; pt, anterior perforated space; pv, pons Varolii;7, mesal or inner root of olfactory nerve; rt, lateral root of olfactory nerve; pr, postrhinal fissure; sy, Sylvian fissure ; $, superior rectus muscle ; tz, corpus trapezoideum ; x, external arciform fibers. = 190 THE NERVOUS SYSTEM. TQl transverse fibers which on either side forms the middle peduncle of the cerebellum, commonly called the crus cerebelli ad pontem medulle. ‘The fibers originate either in cells of the medulla or those of the cerebellum. The crura cerebr1, or peduncles of the cerebrum, the ventral portions of which are continued as the anterior pyramids (Fig. 90), are seen just cephalad of the pons. Their fibers unite the cerebrum to the rest of the brain and the spinal cord. In the space between the crura and the optic chiasm is a prominent projection, the terminal nodular portion of which is the pituctary body or hypophysts. It occupies the pituitary fossa of the skull and is usually torn off in removing the brain. Caudad of the hypophysis are two small rounded white bodies, the corpora albicantia. ‘The tuber cinereum, a slightly elevated mass of gray matter behind the optic chiasm, bears on its surface the funnel-shaped stalk, the enfundibulum, to which the hypophysis is attached. If the two latter parts are removed, there is seen a small elongated aperture through the tuber cinereum into the third ventricle (Figs. 90 and 92). The optic commissure, or optic chiasm, is the commissure formed by the crossing of the optic nerves just cephalad of the tuber cinereum. The prolongation of the optic nerves dorsad from the optic commissure forms the optic tracts, partly covered by the temporal lobes. On either side of the median fissure just cephalad of the optic chiasm is a somewhat triangular area known as the anterior perforated space because of the numerous vessels that enter the brain in this region. Laterally this Space is bounded by the lateral olfactory tract or lateral root of the olfactory nerve, which presents the appearance of a band of white fibers extending from the olfactory lobe into the temporal lobe. The mesal or inner root of Ig2 ELEMENTS OF MAMMALIAN ANATOMY. the olfactory nerve is seen adjacent to the median ventral line cephalad of the anterior perforated space. The olfactory lobes project from the cephalic ventral portion of the cerebrum and give origin to the first poe of cranial nerves. Internal Structure.—The canalis centralis, a small canal extending ee ouenout the center of the spinal cord: enlarges in the region of the brain, forming four cavities or ventricles communicating with each other by narrow channels. ‘The brain is there- fore to be considered as a hollow structure. The first and second ven- tricles, also known as lateral ventricles, occupy the cerebral hemispheres (Fig. HG. 91—_Dtacramor 91): Ihe third and fourth ventricles VENTRICLES OF THE lie in the median line, and are there- BRAIN VIEWED ah onsen fore well seen in a sagittal section of ah, Anterior horn of the brain (Fig. Q2). the right lateral ven- $ . of Sylvius; cc, can- fourth ventricle is visible on the dorsal alis centralis of the ‘ spinal cord: 3 and aspect of the medulla oblongata (Fig. tC third d fourth P S 6 Wonttidles- m, fora. 92)0 Lt dis abet: three cemtinterem men of Monro; m, long by one centimeter wide, and lies middle horn or cor- ‘ nu of the ventride. ventral to the cerebellim. | This veu- tricle is merely an expansion of the canalis centralis of the spinal cord. Its roof is very thin and consists of two portions, one of which, the superior medullary velum, sometimes called the valve of Vieussens, covers the cephalic half of the ventricle; the other portion is the inferior medullary velum, lying over the caudal half. The latter velum is composed of a fold of pia mater tucked in between the cerebellum and medulla, in addition to a layer of epithelial cells on the ventricular THE NERVOUS SYSTEM. 193 aspect of the pia mater. Some nervous matter in addi- tion to the pia mater and epithelium forms the superior velum. ‘Two longitudinal vascular fringes, hanging from the roof of the ventricle on either side of the mid-line, | form the choroid plexus, which is merely a network of blood-vessels carried by a reflected portion of the pia mater. Cephalad the fourth ventricle is continued as a small canal, the ater, or aqueduct of Sylvius, which lies ventrad to the corpora quadrigemina and opens into the third ventricle (Hie -92).. The latter is a narrow, vertical, cleft-like space between the optic thalami.. The two thalami are united by the soft or middle commissure, better designated as the massa intermedia, extending through the ventricle. Unless this ventricle has been injected with a starch mass through the infundibulum before the brain was hardened, its cavity will not exceed a millimeter in width. The roof is formed much in the same manner as that of the fourth ventricle, by a re- flection of the pia mater lined with epithelium (Figs. 92 and 94). A sagittal section of the brain placed in a pan of water will show the fold of pia mater called velum interpositum extending cephalad from the pineal gland. Two folds of the pia mater hanging on either side from near the median line form the choroid plexus as in the fourth ventricle. The body of the fornix lies dorsad of the membranous roof of the ventricle. In the floor lie the corpora albicantia, the infundibulum, the tuber cinereum, and the optic commissure. Cephalad the third ventricle communicates with the lateral ventricles by slit-like apertures, the foramina of Monro, passing laterad and ventrad of the anterior pillars of the fornix. The lateral ventricles are found in the cerebral hemi- spheres ventrad to the corpus callosum. They are the IQ4 ELEMENTS OF MAMMALIAN ANATOMY. largest ventricles of the brain. In order to view them satisfactorily, the entire dorsal portion of the brain down to the corpus callosum must be cut away, and a hole cut through the corpus callosum. A number of cross- sections of the cerebral hemispheres should also be studied. Fic. 92.—SAGITTAL SECTION OF THE BRAIN. ac, Anterior commissure; av, arbor vite; c, habena; cc, canalis centralis; cb, cerebellum; cm, middle commissure or massa intermedia; cr, sulcus crucialis; chg, corpus quadrigemina; cx, choroid plexus of third ventricle—the dark line dorsad of cx is the velum interpositum ; f, sulcus splenialis; fr, frontal lobe of cerebrum; jn, anterior pillars of the fornix; im, infundibulum; 7, iter, or aqueduct of Sylvius; k, genu of corpus callosum; /mx, lamina terminalis; m, splenium; mr, sulcus marginalis; med, medulla; op, optic chiasm; oc, occipital lobe; ol, olfactory lobe; pn, pineal gland; fo, pons Varolii; pc, posterior commissure; pv, inferior medullary velum; pvv, superior medullary velum or valve of Vieussens; 3 and 4, third and fourth ventricles. Each ventricle is composed of a body from which pro- jects an anterior cornu and a middle or descending cornu. The former extends into the frontal lobe and thence into the olfactory lobe, and the latter descends into the temporal lobe. The roof of the body of the lateral ven- tricle is formed by the corpus callosum (Figs. 92, 93, and 94) and the mesal wall by the septum lucidum, a THE NERVOUS SYSTEM. IQg5 mass of gray matter lying between the fornix and the corpus callosum. A fringe of pia mater projects through the foramen of Monro into the lateral ventricle, where it forms the choroid plexus. The lateral ventricles are lined with the epithelial layer common to the other ventricles. These cavities within the central nervous system result from the manner in which the brain and cord are formed. In the embryonic life of most vertebrates the nervous system appears as a trough of matter extending dorsally throughout the length of the body. The sides of this trough grow dorso-mesad, thus forming a roof and thereby converting the trough into a canal which in the spinal cord becomes the canalis centralis, and in the brain the ventricles. This continuous cavity of the central nervous system contains a fluid having the nature of lymph. The Commissures of the Brain.—The paired portions of the brain are united across the median line by bands of fibers known as commissures, two of which are visible on the ventral surface of the brain, and the others may be seen in a sagittal section (Fig. 92). The pons Varolw. is the commissure on the ventral aspect of the medulla. Its fibers pass into the cerebellum on either side, forming the middle peduncle or crus cerebelli ad pontem. The optic commissure or optic chiasm is formed by the crossing of the optic nerves, cephalad of the tuber cinereum. Some of the fibers originating in the cells of the retina of one eye pass by this commissure directly to the cells in the retina of the other eye, while a second set passes from the eye to the optic tract on the opposite side of the brain, and still a third set, originating. in one corpus quadrigeminum, passes by the optic commissure direct to the opposite corpus quadrigeminum (Figs. 92, TOO). 196 ELEMENTS OF MAMMALIAN ANATOMY. The corpus callosum is the largest commissure of the brain. It joins the two cerebral hemispheres, and forms the roof of the lateral ventricles. This broad plate of fibers (Figs. 92, 93, 94, 95), which may be seen at the bottom of the great longitudinal fissure by pressing the hemispheres slightly apart, is about one millimeter thick and three centimeters wide. Laterally the fibers radiate in all directions to the gray matter of the cortex. The ventral bend of the median cephalic portion of the callosum is the genu or knee. The caudal border is the splenvum. | The fornix lies ventral to the callosum (Figs. 92 and 94) and consists of a median plate of fibers, the body, two posterior columns, and two anterior columns or pullars. The median plate or body of the fornix sends some fibers into the ventral surface of the callosum. From the cephalic border of the body near the median line the two anterior columns, or pillars, descend in a curve, forming the cephalic boundary of the third ventricle as far ventrad as the anterior commissure. Here the two columns diverge slightly from the median line, but con- tinue their descent, curving caudad to their termination in the corpora albicantia. The posterior columns, or crura, descend from the caudal border of the body, curving laterad into the median cornu of the lateral ven- tricle, and gradually unite with the cornu ammonis. The cornu ammontis, or hippocampus major, is a thickened projecting fold of the wall of the median cornu (Fig. 93). The free lateral margin of the posterior pillar or crus of the fornix is the fimbria, or tenia hippocampi. Adjacent to the median line in either hemisphere, a thick lamina of matter, the septum lucidum, stretches from the cephalic _ part of the fornix dorsad to the callosum. The very narrow cavity formed by the adherence of the margins THE NERVOUS SYSTEM. IQ7 of the septum of one hemisphere to those of the septum in the other hemisphere is sometimes called the fifth ventricle. Between each anterior pillar of the fornix and Fic. 93.—DorsAL, ASPECT OF THE BRAIN WITH THE CEREBELLUM AND THE DorRSAL THIRD OF THE CEREBRUM REMOVED AND MOST OF THE Corpus CaLLosum CutT AWAY FROM THE RIGHT HALF. ac, Right anterior corpus quadrigeminum; c, commissure of the quadri- gemina; ca, the united superior and inferior peduncles of the cere- bellum ; cr, the middle peduncle or crus cerebelli ad pontem; cs, corpus striatum ; ct, edge of corpus callosum cut slightly to the left of the median line; cal, dorsal surface of the callosum into which a hole has been cut; hp, hippocampus major, or cornu ammonis, in the median cornu of the lateral ventricle; h, hippocampus major near where it is joined by the fibers of the crus of the fornix; 2, uncut portion of the callosum; md, medulla oblongata; n, anterior columns or pillars of the fornix; 0, gray cortex of the cerebrum; , posterior crus of the fornix; pn, pineal gland, cephalad to which is the heavy white line, the commissure of the habene or tenie thalami; pp, funiculus gracilis; rc, funiculus of Rolando; 1, funiculus cuneatus; ts, one of the testes or posterior corpora quadrigemina; x, body of the fornix. the optic thalamus is a cleft, the foramen of Monro, leading from the third ventricle, laterad of the septum lucidum, into the lateral ventricle. 198 ELEMENTS OF MAMMALIAN ANATOMY. The three remaining commissures are known according to their location as the anterior, middle, and posterior. The anterior commissure (Figs. 92 and 95) perforates the corpora striata, extending across the median line imme- diately cephalad of the anterior pillars of the fornix. It is about two millimeters in diameter. The middle com- missure, or massa intermedia, lies between the optic thalami. It is sometimes called the soft. or gray com- missure. It is nearly one centimeter in diameter and passes through the third ventricle (Fig. 92). The pos- terior commissure is a cord of fibers about a millimeter in diameter connecting the caudal portions of the optic thalami. The Basal Ganglia.—A semi-independent group of nerve cells forming a definite mass is known as a ganglion. In the ventral portion of the brain lie three pairs of large ganglia, called corpora quadrigemina, optic thalamz, and corpora striata. ‘To study them, the entire dorsal surface of the brain down to and including the corpus callosum should be removed. The corpora quadrigemina (Fig. 93) lie cephalad of the medulla, and consist of an anterior pair, the nates, and a posterior pair, the testes. A narrow canal, the iter, or aqueduct of Sylvius, leads from the fourth ventricle through the corpora quadrigemina (Fig. 92) from the fourth ventricle to the third ventricle. The nates lie nearer to the midline than the testes, which are slightly separated by a depression occupied by the middle portion of the central lobe of the cerebellum. The testes are united by a white commissure. The posterior commis- sure of the brain unites the cephalic portions of the nates (Fig. 92). Its cut end may be seen ventrad to the base of the pineal gland. Laterally each pair of the corpora quadrigemina is THE NERVOUS SYSTEM. IQQ prolonged into two white bands, the anterior and pos- terior brachia. ‘The latter are about a half centimeter long, and pass forward beneath a pisiform ganglion, the corpus geniculatum wnternum or mediale. ‘The anterior brachia pass from the cephalic end of the nates laterad beneath the caudal projections of the optic thalami, where they join the optic tracts. Fic, 94.—CROSS-SECTION OF THE BRAIN IN THE PLANE x IN FIG. 92. The plane is just caudad of the optic chiasm. 1 and 2, First and second or lateral ventricles; cr, corpus callosum; cm, anterior pillars of fornix; cx, choroid plexus of lateral ventricle; cx’, choroid plexus of third ventricle; cxt, gray cortex; ea, ependyma or endyma lining the ventricles; 7, median longitudinal fissure; h, habena, or tenia thalami; mc, middle commissure, or massa inter- media; n, fibers of the optic tract as they enter the external genic- ulate body s; 0, fornix ; 7, caudal portion of nucleus lenticularis ; op, optic thalamus; oc, optic tract as it leaves the chiasm; s/, septum lucidum; vn, part of third ventricle dorsad to the commissure; v, third ventricle; ¢, fibers of optic tract. Homologues of the corpora quadrigemina exist in all vertebrates. In them originate largely the optic nerves, and therefore their size is in proportion to the animal’s power of sight. In the mole, which has little use for eyes, the anterior pair is rudimentary. The optic thalami form the largest pair of basal ganglia, and lie cephalad of the corpora quadrigemina and form 200 ELEMENTS OF MAMMALIAN ANATOMY. the lateral walls of the third ventricle, across which they meet, forming the massa intermedia, or middle com- miussure. é 7 On the dorsal aspect of each thalamus, near the median line, is a longitudinal band of white fibers called the habena, or tenia thalami, which at its caudal limit is united to its fellow by the commissura habene. ‘The thalamus is composed largely of gray matter, but there are two important bundles of fibers, known as the optic tract and internal capsule (Fig. 94), appearing on its lateral surface. The optic tract, of which the optic nerve is a continuation, arises by two roots, the larger of which comes from the cells forming the lateral geniculate body, which is the lateral and caudal projection of the thalamus. The internal capsule, well shown in a transverse section, is composed mainly of the fibers descending from the cells of the parietal region of the cortex. The pineal gland, or pineal body (Fig. 92), is a conical projection about a half centimeter long, from the caudal part of the dorsal surface of the thalamus. It is a ves- tigial structure which in some of the lower vertebrates in early geological time functioned as a third eye. In Hatteria, a New Zealand lizard about a foot long, the eye is present, projecting slightly through a foramen in the parietal bone. ‘Traces of this third eye with a lens have also been noticed in the embryo of the viper and some of the lizards. The corpora striata are the most cephalic of the basal ganglia and are somewhat pear-shaped, the larger ends being cephalad and nearer the median line than the caudal portions, which curve laterad around the optic thalami (Fig. 93). They form a part of the floor of the lateral ventricles, and are pierced by the anterior com- missure (Fig. 95), a small cord of white fibers. THE NERVOUS SYSTEM. 201 The corpus striatum consists of both white and gray matter. The latter, composed of cells, is disposed in two chief nuclei or masses, known as the nucleus cauda- tus, lying median and cephalic, and the nucleus lenticu- laris, which is more lateral and caudal (Fig. 95). The center of the nucleus lenticularis is laterad of the optic thalamus and dorsad of the crus cerebri. A thin layer of white matter, the /amina semicircularts, separates the ba n cm fe Fic. 95.—CROSS-SECTION OF THE BRAIN THROUGH THE ANTERIOR COM- MISSURE. an, Arachnoid; ce, external capsule; cl, corpus callosum; cm, anterior commissure ; fxc, falx cerebri; 7, great longitudinal fissure; jx, anterior pillars of the fornix; zc, internal capsule; n, radiating fibers of cal- losum ; 2n, septum lucidum; nc, nucleus caudatus of corpus striatum; 1, nucleus lenticularis; p, pia mater; v/s, superior longitudinal sinus; vn, third ventricle; v, lateral ventricle. optic thalamus from the nucleus caudatus. A few fibers from the crus cerebri form the lamina semicircularis, whose edge may be seen in the floor of the lateral ven- tricle on the lateral boundary of the nucleus caudatus. A group of fibers, known as the internal capsule, separates the optic thalamus from the nucleus lenticularis, laterad of which is the external capsule, a group of fibers probably descending from the cells of the cerebral cortex. The two nuclei of the corpus striatum are connected by fibers, 17 202 ELEMENTS OF MAMMALIAN ANATOMY. and other fibers connect these nuclei with the cortex of the cerebrum and the optic thalamus. The Medulla Oblongata.—The medulla oblongata, or myelencephalon, is the stem of the true brain and extends from the point of origin of the first spinal nerve to the pons Varolii. The cerebellum must be removed in order to study carefully the features of the medulla, and as it is cut away the student should notice just ventrad to it the very thin roof of the fourth ventricle. Its caudal portion, composed of a reflection of the pia mater lined with epithelium, takes the name of znferzor medullary velum, and the cephalic part, formed of pia and a thin layer of nervous matter, is called the anter1tor medullary velum, or valve of Vieussens (Fig. 92). The fourth ventricle (Figs. 92 and 93) is an enlargement of the canalis centralis of the cord. The clave, or expan- sions of the funiculi graciles, the three peduncles or crura of the cerebellum, and the testes or colliculi inferiores form its lateral boundaries. Its cavity is shallow and pointed at either extremity. The floor, called fossa rhomboidea, is formed by the continuation of the gray matter of the spinal cord. Where the ventricle is widest a tract of fibers, the strza medullaris, arises from the midline and proceeds laterad to help form the auditory nerve. Laterad of the clava a larger band of fibers, the funiculus cuneatus, runs parallel with a more lateral lying bundle, the funiculus cuneatus lateralis, or funiculus of Rolando. ‘These three bands of fibers compose the restiform body, or inferior peduncle of the cerebellum. On the ventral aspect of the medulla may be seen the anterior pyramids, composed of a band of fibers lying on either side of the median line and apparently emerging from the pons. They form a section of the crossed THE NERVOUS SYSTEM. 203 pyramidal or motor tract connecting the brain with the cord. The olivary eminence lies just laterad of the pyramid. ‘The fact that seven posterior cranial nerves originate from the medulla shows the importance of this part of the brain. The destruction of the respiratory centers, or vital knot, lying ventrad to the caudal end of the fourth ventricle causes instant death. The Cerebellum, or Little Brain.—The cerebellum, which in the cat lies caudad of the cerebrum and dorsad of the medulla, resembles the cerebrum in being com- posed of an outer layer of gray matter or cells and an inner mass of white matter made up of fibers. While within the cerebrum there are several important ganglia or masses of gray matter, in the cerebellum only one chief mass of gray matter, the corpus dentatum, is present in each hemisphere. The outer layer of gray matter, known as the cortex, is folded into numerous convolutions, between which are deep sulci (Fig. 92). The central core of white matter forms an arborescence known as the arbor vite. The cerebellum (Fig. 89) is seen to consist externally of two lateral portions, the cerebellar hemispheres, a median vermiform process and three pairs of peduncles or bands of fibers uniting it with other parts of the brain and cord (Fig. 93). The separation between the hemispheres and vermis or vermiform process is most marked on the cephalic aspect. The peduncles are named, according to their location, superior, middle, and inferior. The middle peduncle, or crus ad pontum, is a dorsal prolongation of the fibers of the pons Varolii (Fig. 90). In order to display the other peduncles a portion of the cerebellum must be cut or picked away with the forceps. The superior one, known also as the brachiwm conjunctivum, extends as a cord 204 ELEMENTS OF MAMMALIAN ANATOMY. of fibers along the cephalic half of the fourth ventricle beneath the corpus quadrigeminum. The inferior pedun- cle, or restiform body, forms part of the boundary of the caudal half of the fourth ventricle and enters the cerebellum between the other two peduncles. It is com- posed largely of fibers from the spinal cord. PRACTICAL QUESTIONS AND SUGGESTIONS. . Describe the meninges of the central nervous system. . Which of the five parts of the brain are exposed dorsally? . Draw the lateral aspect of the brain and label all features. . Draw the ventral aspect of the brain and label all features. 5. Draw the dorsal aspect of the brain after the dorsal portion, in- cluding corpus callosum and fornix, has been removed. 6. Describe the differences existing between the gyri and sulci of your specimen and the one described in the text. 7. Write a description of the ventricles, giving dimensions and bound- aries. 8. Describe the attachment of the pineal body. 9. Which of the cranial nerves derive their name from their function? 10. Name the foramina giving passage to one or more of the cranial nerves. 11. From which of the five parts of the brain do most of the cranial nerves originate? 12. Describe the choroid plexus. 13. What is the internal capsule? 14. Draw a cross-section of the brain made by cutting through the optic commissure and label all parts. 15. Draw a cross-section of the brain made by cutting through the middle commissure and label all parts. 16. Draw a cross-section of the brain made by cutting through the corpora quadrigemina and label all parts. 17. Write a description of the corpus callosum. 18. Which is the smallest commissure of the brain? 19. Explain the difference in structure between the white and gray matter. 20. Describe the cerebellum. Bm WN THE NERVOUS SYSTEM. 205 THE SPINAL CORD. The spinal cord extends from the foramen magnum through the vertebral canal. It is more or less cylindrical throughout and has a diameter of about one centimeter except in the lumbosacral region, where it grows gradu- ally smaller until it is only one or two millimeters in diameter. In order to study the cord, one should have a mounted transverse microscopic section, an entire cord am situ with the dorsal wall of the vertebral canal re- moved, so that the exit of the spinal nerves may be seen. The membranes which envelop the spinal cord are the same as those that envelop the brain. The dura mater is the external tough coat; the pia mater, the internal delicate vascular coat sending a process deep into the anterior fissure on the ventral side; and the arachnoid, the very thin membrane between the two preceding. The arachnoid lies close against the dura mater, but is separated from the pia mater by the subarachnoid space, which is filled with a serous fluid called the cerebrospinal fluid. It is apparently the same as that in the ventricles of the brain, and seems to be of a lymphoid nature. In fact, the subarachnoidean space is merely a large lymph space similar to the cavities of the pleura and peritoneum. This lymph, or cerebrospinal fluid, proba- bly escapes from the thin walls of the capillaries covering the pia mater and is taken up by lymphatic vessels which begin in open mouths on the walls of the space. The cord presents two enlargements, the cervical, whence issue the nerves of the forelimbs, and the lumbar, giving origin to the nerves of the posterior limbs. Two deep fissures, the anterior median and the posterior median, penetrate about one-third through the cord, incompletely dividing it into halves longitudinally. The 206 ELEMENTS OF MAMMALIAN ANATOMY. pia mater is prolonged into the anterior fissure, but not into the posterior fissure. Slightly laterad of the anterior median fissure issue the anterior roots of the spinal nerves, and at about the same distance from the posterior median fissure are the posterior roots of the spinal nerves. These two roots unite about one centimeter from their origin (Fig. 90). On the posterior or sensory root is a small ganglion located very near the junction of the two roots. The common spinal nerve, formed by the union of the two roots, almost immediately divides into four branches, one of which, the dorsal, supplies the muscles and skin along the vertebral column; a second, the ven- tral branch, supplies the limbs or intercostal spaces; while the other two branches, rami communicantes, join the adjacent ganglion of the sympathetic cord (Fig. 103). Each of the four branches contains both motor and sen- sory fibers, or, in other words, fibers from both roots. The exit and entrance of the nerve roots divide the white matter of the lateral half into three columns named, according to their location, the anterior column, the lateral column, and the posterior column. The first is ventral to the anterior nerve roots, the last is dorsal to the posterior nerve roots, while the lateral column is between the roots. The elements of the spinal cord, like those of the brain, are of two kinds—the cells composing the gray matter and the fibers composing the white matter. While in the brain the gray matter is largely on the surface, forming the cortex, in the cord it occupies the central region. A canal, the canalis centralis, about one- half a millimeter in diameter, extends throughout the cord, opening into the fourth ventricle of the brain. A cross-section of the cord shows the gray matter arranged in the shape of a letter H. The ventral columns of gray THE-NERVOUS SYSTEM. 207 matter are the anterior horns, and the posterior columns, the posterior horns (Fig. 96). Many of the fibers extend in a longitudinal direction throughout the cord, but the roots of the spinal nerves upon entering the cord run transversely a longer or shorter distance, and in many cases cross to the opposite side. It is thought that the anterior root fibers are, for em Fic. 96.—DIAGRAMMATIC CROSS-SECTION OF THE SPINAL CorpD. The cells and fibers are represented too few and too large in proportion to the size of the cord. ag, Anterior horn or column of gray matter; a, nerve process of the cell c; an, anterior root; cc, canalis centralis; c, one of many cells forming the ganglion on the posterior root; d, posterior fissure; e, cell giving off an axis-cylinder process into the anterior root; dn, dorsal branch; 7, cut-off fibers; gn, ganglion of posterior root; 2, axis-cylinder pro- cess of the cell 20; nc, junction of anterior and posterior roots; ps, posterior root of nerve; pg, posterior horn of gray matter; s, terminal arborization of part of fiber fromc, v, anterior median fissure; vn, ventral branch of nerve; van, axis-cylinder process of anterior horn cells; x, the part of the posterior root fiber extending caudad in the cord. the most part, the axis-cylinder processes of the cells in the anterior horn (Fig. 98). Each posterior root fiber after passing into the cord separates into two parts one of which extends cephalad, the other caudad (Fig. 98). Both give off branches at right angles, called collaterals, which terminate in arbori- zations about the cells of the cord. 208 ELEMENTS OF MAMMALIAN ANATOMY. Each nerve cell presents two kinds of processes, proto= plasmic processes or dendrites and an axis-cylinder pro= cess (Fig. 97). The dendrites, except in the ganglia outside of the central nervous system, are usually several in number and comparatively short, while there is but \ Fic. 97.—CELL FROM THE CENTRAL NERVOUS SysTEM. 100. a, Dendrites or protoplasmic processes; ax, axis-cylinder process; n, nucleus of the cell body. one axis-cylinder process from each cell, which may be more than a foot in length. A number of axis-cylin- ders (nerve fibers), each of which is surrounded by a sheath, the neurilemma, constitutes a nerve bundle or nerve. Every axis-cylinder or nerve fiber originates in a cell, but terminates freely either within the central x ~ JEN frac------- Fic. 98.—DIAGRAM SHOWING THE RELATION OF SOME OF THE CELLS AND FIBERS OF THE SPINAL CorD. Lateral aspect of the cord. a, Anterior median fissure; ac, cells of the anterior horn; an, anterior root of spinal nerve; c, axis-cylinder process; co, collateral fibers; e, fibers connecting higher brain centers with cerebellum; fz, sensory fibers of fillet to the brain; g, gn, go, ganglion of posterior root; gr, gray matter; 77, fibers of the posterior sensory tract; /, fibers to cerebellum ; m, cells in the anterior horn or column of gray matter; , spinal nerves; o, cells in the posterior horn or column of gray matter; nc, nucleus gracilis and nucleus cuneatus; mr, nucleus ruber; 7, a fiber of pos- terior root; rb, ganglion cells of medulla; s, tract of fillet to the brain; sp, fibers of superior peduncle of the cerebellum; 7%’, fiber of crossed pyramidal tract; ts, point of decussation; v, division of fiber x into es cephalic and caudal extensions; w, a collateral of the longitudinal ber zr. 18 209 210 ELEMENTS OF MAMMALIAN ANATOMY. nervous system or in some other part of the body (Figs. 97, 98). Within the central nervous system a fiber usually ends in an arborescence which may be contiguous but not continuous with the dendrites of another cell. The nerve processes have the power of conducting impulses whether derived from the cell itself or an external stimulus. The dendrites conduct impulses to- ward the cell, while the axis-cylinder conducts them from the cell. The sensory fiber 7 (Fig. 98) leads from the dermis of the cat’s paw. A pin-prick in the paw causes an impulse to be transmitted along the fiber to the cell g, and thence by its axis-cylinder, x, to the point v within the cord where the fiber splits. From the point v the impulse will proceed both through the ascending portion of the fiber, 27, and the collateral, w. By the latter route it will stimulate the cell m, whose axis- cylinder terminates in the foreleg muscles, which are thereby made to contract and pull the paw away from the irritating object. This process may take place without consciousness, and is then known as reflex action. If, however, the impulse travels along the fiber zr, and thence through the fiber s to the brain, whence an im- pulse descends through the fiber ?’, ts, the process is known as voluntary reaction. é THE FIBER TRACTS OF THE CENTRAL NERVOUS SYSTEM. ) As before stated, the white matter of each half of the cord is divided by the exit and entrance of the nerve roots into three columns—anterior, lateral, and posterior. Each of these columns is subdivided into tracts which have special names and special functions (Fig. 99). THE NERVOUS SYSTEM. 211 In the posterior column two tracts are recognized: the fasciculus of Goll, occupying the mesal third of the column, and the fasciculus of Bur- dach, composing the remainder. In the medulla of the cat these two tracts may be distinguished by the unaided eye (Fig. 93). They are here called the funtzculs of Goll and Burdach, or funiculi gracilis and cuneatus. Their fibers are largely, if not entirely, the axis-cylinder processes of the ganglion cells on the posterior roots of the spinal nerves. They terminate in the nu- clei gracilis and cuneatus, two small masses of nerve cells in the medulla laterad of the fourth ventricle (Fig. 98). That these fibers are processes of the spinal ganglion cells is proved by the fact that they degenerate if the posterior nerve roots are Severed: iclose) to) the cord: In whales, where the pelvic extremi- ties are wanting, the fasciculi of Goll and Burdach are very small. The lateral column is composed of five tracts: the direct cerebellar tract, the antero-lateral descending cerebellar tract, the antero-lateral ascending cerebellar tract or Gow- ers’s tract, the lateral ground bun- dle,and thecrossed pyramidal tract. Fic. 99.— DIAGRAM OF SomE FIBER ‘TRACTS. DorsAL ASPECT. al, Antero-lateral ascend- ing cerebellar tract; c, posterior corpus quad- rigeminum; cer, lateral lobe of cerebellum, whose median portion is removed; cg, the two fasciculi of Goll and Burdach represented as one; cp, crossed pyra- midal or chief motor tract; cp’, crossed pyra- midal tract in the region of the cerebral pedun- cle; dc, direct cerebellar tract; fz, the large part of the fillet derived from nc; nc, nuclei gracilis and cuneatus; s, decus- sation of pyramidal tracts; x, sensory or superior pyramidal de- cussation; sp, superior peduncle of cerebel- lum. The direct cerebellar tract occupies the superficial re- gion of the cord laterad of the posterior cornu of gray 212 ELEMENTS OF MAMMALIAN ANATOMY. matter. Its fibers originate from the cells of the more central portion of the gray matter throughout the cord and terminate in the cerebellum. Its fibers help to form the inferior peduncle of the cerebellum. | The antero-lateral descending cerebellar tract occupies the superficial area ventrad of the anterior horn of gray matter. Its fibers originate in the cells of the cerebellum and extend caudad in the cord. The antero-lateral ascending cerebellar or Gowers’s tract occupies the superficial area laterad of the anterior horn. Its fibers probably originate in the cells of central gray matter throughout the cord, and largely terminate in the cerebellum. The lateral ground bundle consists largely of fibers with a short course, many of which are commissural, connecting the two halves of the spinal cord. The crossed pyramidal tract contains the longest fibers of any of the tracts of the central nervous system and occupies a large area just laterad of the posterior horn of gray matter. Its fibers originate in the cortical cells of the brain near the crucial sulcus (Fig. 89), and descend as part of the internal capsule, through the corpus striatum and laterad of the optic thalamus to the base of the brain. Here it is one of the three main tracts forming the crus or peduncle of the cerebrum, whence it extends through the pons Varolii, appearing along the median ventral line of the medulla as the pyramid (Fig. 90). At the caudal end of the medulla it crosses dorsad to the opposite side of the cord to occupy the area laterad of the posterior horn of gray matter. Its fibers terminate largely in arborizations around motor cells of the cranial nerves in the brain, and the cells in the anterior horn of gray matter, from which originate the motor fibers for the muscles of the body. Therefore it is apparent that this tract controls largely the muscular activities THE NERVOUS SYSTEM. 213 of the entire body (Figs. 98, 99, and 100). ‘The crossing of the fibers of this tract in the caudal region of the medulla is known as the motor decussation or the de- cussation of the pyramidal tract. The limits of these various fiber tracts of the central nervous system cannot be determined by dissection. They have been worked out largely by experimental ‘physiology and pathology, and by studying their embry- onic development when the fibers of different tracts are seen to acquire their sheaths (neurilemmee) at differ- ent periods. ‘The portion of a nerve fiber separated from its cell degenerates, so that if the fibers of the crossed pyramidal tract were injured by accident or disease in the region of the medulla, all that part of the tract in the cord would degenerate, in consequence of which the subject would suffer paralysis. The larger portions of the tracts thus far described have been confined to the cord, while the remaining tracts to be discussed concern chiefly the brain. In order to understand these it is necessary to remember that the cortex of the brain is composed of millions of nerve cells which give origin to nerve fibers extending to other portions of the cortex, to the basal ganglia, the cerebellum, medulla, and spinal cord (Fig. 100). Like- wise some of the fibers originating in the cells of the cord, medulla, cerebellum, and basal ganglia terminate about the cells of the cortex. The cord, medulla, and cere- bellum are connected with the higher brain centers by the fibers of the cerebral peduncles (Figs. go and 100), which are separated into two parts by an elongated mass of gray matter, the substantia nigra. The dorsal part is known as the tegmentum, while the ventral part is the crusta. The fibers of the brain are of three kinds—the com- 214 ELEMENTS OF MAMMALIAN ANATOMY. missural fibers, the projection fibers, and the association fibers. The first-named constitute the commissures of the brain previously described (Figs. 90, 92). In addition to these commissures, numerous other fibers cross to the opposite half in that portion of the brain caudad of the optic thalami. The internal portion of the medulla Sn S ; a: Go Fic. 100.—D1aGRAM OF CHIEF FIBER TRACTS OF THE MAMMALIAN BRAIN. LATERAL ASPECT. a, b, c, d, e, Fibers forming internal capsule; ac, anterior corpus quad- rigeminum; cb, direct cerebellar tract; cr, crossed pyramidal or chief motor tract; cs, cortico-pontine or secondary motor tract; m, middle peduncle of cerebellum; ng, nuclei gracilis and cuneatus; n, decussation of crossed pyramidal tract; 0, optic thalamus; oc, optic chiasm; pc, posterior corpus quadrigeminum; pons, transverse fibers of pons Varolii; 7’, pyramids formed by pyramidal tract; pl, posterior longitudinal bundle; rn, nucleus ruber; s, antero-lateral cerebellar tract; sn, substantia nigra; sp, superior cerebellar peduncle; st, corpus striatum; ¢, fibers of the fillet or great sensory tract. oblongata possesses numerous transverse fibers which, with the longitudinal fibers, form a kind of reticulum in the midst of the gray matter, known as the jormatio reticularis. The projection fibers (Fig. 100) are those connecting the cortex with the lower brain centers and the cord. The chief motor tract is the crossed pyramidal tract THE NERVOUS SYSTEM. 215 already described in the cord. It may be traced from the pyramids to its origin in the cortex in the region of the crucial sulcus (Fig. 89), by slicing away the ventral portion of the brain obliquely in a plane joining the cephalic margin of the pons and the crucial sulcus. Num- erous fibers are given off by this tract to the motor roots of the cranial as well as the spinal nerves. The secondary motor tract, cortico pontine tract, carries motor impulses from the frontal cortex to the medulla, whence other fibers convey them to the opposite half of the cerebellum. The axis-cylinders of the cells here transmit the impulses through the inferior peduncle to the cells in the anterior horn of gray matter of the cord. The great sensory tract of the brain is the fillet. - Its fibers originate largely in the cells of the nuclei gracilis and cuneatus of the medulla (Figs. 98, 99, 100) and cross over to the opposite side of the medulla, forming the sensory or superior pyramidal decussation. ‘This tract receives also fibers from the spinal cord, the cerebellum, and the medulla oblongata. These projection fibers, after leaving the peduncular region, turn dorsad to pass with others through the corpus striatum and laterad of the optic thalamus. In this part of their course they form what is known as the nternal capsule (Fig. 95). The spreading out of the projection fibers just beneath the cortex of the cerebrum forms the corona radtata. The association fibers are those which connect different portions of the same cerebral hemisphere. Two kinds are recognized. The short fibers connect adjacent convolutions, while the long ones place in communication two remote portions of a hemisphere. 216 ELEMENTS OF MAMMALIAN ANATOMY. PRACTICAL QUESTIONS AND SUGGESTIONS. 1. Describe the membranes of the cord. 2. What difference in the size of the nerve roots in the various regions of the cord? 3. Draw a cross-section of the cord showing all features visible to the naked eye. 4. How does the arrangement of the gray matter of the cord and brain differ? 5. Describe the processes of nerve cells. 6. In what portions of the body are nerve cells found? 7. What is the location of the cells whose protoplasmic processes largely make up the tracts of Goll and Burdach? 8. What part of the cord is occupied by the chief motor tract? 9. What tracts of the cord originate or terminate within the cere- bellum ? 10. Describe the course of the crossed pyramidal tract throughout the axial nervous system. 11. Describe three bundles of commissural fibers in the brain. 12. Which tract of the projection fibers contains the longest axis- cylinder processes? 13. Describe the great sensory tract of the brain. 14. What do the association fibers connect? 15. Tell what is known of the functions of various regions of the cortex. 16. Explain why paralysis of the left side of the body would result from an injury to the right motor region of the cortex. 17. Procure a piece of spinal cord from the butcher-shop. Smear a bit of the gray matter on a glass slip, dry, then stain in hematoxylin, wash, and after drying mount in balsam. Draw and describe nerve cells thus found. THE PERIPHERAL NERVES. All portions of the head, trunk, and limbs of the cat are supplied with nerve fibers which are in communication with the central nervous system by means of fifty-two pairs of nerve bundles, forming what are known in the brain region as the cranial nerves and in the region of the cord as the spinal nerves. The Cranial Nerves.—There are twelve pairs of cranial nerves, all of which pass through foramina in the base of the skull, and all except one, the tenth or vagus, are ‘soposnur onsu0j ‘sejosnur proAy, ‘sIop[noys pue Yoou jo sapsnyl ‘purys prorAy} pue ‘you -l10}s ‘ssuny ‘reo ‘snseydoso ‘egayoely ‘xuAiey ‘xuAreyg ‘Ie9 B]PpIul pue ‘xuAreyd ‘9ze7ed ‘sjisuo} ‘ansuo Ly "Ied [CUIOUT ‘spurs Areyixeuqns pue prjored ‘Q0eJ pue peoay jo saposny ‘TTeqeAe oy} Jo snzoor [euII} xX] ‘purls prjored puv ‘onsu0} 7799} Jepnqipueuw ‘uors -d1 Ie[Nqipueur jo JuSUINSezUT | "YI994 Azeyrxeur pue worser Arey -[Ixeum pue 9s0u jo JUSTIN 39} UT ‘JIQIO Jo UoOTseI UT JUOUT -n39}UT pue purys jeurAiyoR’y ‘anbiqo torredng ‘onbiyqo toriedns pur ‘euis} x9 94} Jdev0xe aAd Jo sopOsNur 1399y "BUTI ‘IUBIQWIOU ULIIOpIauyoS ‘NOILNAIULSIG "sntIo} -ue wWIneplojApuoD UsUIeIOT ‘goueuttmoid Are -ATJO Jo wortjI0d jepnes-o19}e’] ‘SnSeA 94} IvoU JUIOd 0} DAIOU [CIATION YIXIS Woy P]]Npour pure piod ut sjoo1 jeloaos Ag ‘uoureio; Iejnsnfl 10 ‘sniioysod winisov, UslIeIOy ‘Houreioy Iejnsnfl 10 ‘Surpooeid ‘sniiojsod winis0"] UOUIeIO\T ‘uouIeIO; Iejnsnf 10 ‘sulpoooid ‘sniiojsod umMis0e, UsUIeIOY | 24} JO pepneos AjoyeIpsmUy ‘Surpoos1d ‘SNUIDJUL SNEIO}IpNe snyesyy | 94} Jo pepneos Ajo}erIpouruy “WOUIeIOF ployseur proyAjs ‘manized pue snidoyey jo Jonpoenby | -e1} Jo uors0d oyerydeo-0107e’] pre ‘SniIoJUe WNIs0"] UsUIeIO | -e1Ad oy} Jo pei9}e] UINIzedery ‘HOISIAIP Iejnqipueur Jo pilIyj—e[eao usUIeIOY “IOISTA -Ip Ale][Ixeul 10 puoses F —umnpunjor wouleioy WoreA suod jo worger [epne) "MOISIAIP ormyeyzydo 30 4s1y— SNLIOJUe WINIOR] USMIeIO YT ‘SUIpsoeid se oureg ‘ginssy [eprousyds Io ‘snijojue UINIooR, UsUIeIO ‘HetUIeIOF 913d0 ‘plowuryje Jo euIMIeIO ‘INeA AIv][Npsur 1olIUW ‘suod 91} jo pereydso oul UeIpou 34} IvaN ‘WUseIyS 311dO ‘soqoy, A10DEIO 347 jo pepnes Ajo}erIpowmury , “snssopsodAy{ ‘Atossooor [eurdg ‘o1I}sesounoud 10 snseA ‘jeasudAreydosso[s) “AIOJIPHY TepRy -suaonpqy a ‘[CINVJII} IO [VUTMIISIIT, “Tes YOOI} IO oye "IOJOULOTNHIO ‘odo "£10PI[O “TTNAS WOAH LIXH “NISIANO TWIOI4dadnAsS “SHAYHN TVINVAO ei N 218 ELEMENTS OF MAMMALIAN ANATOMY. distributed to structures of the head and neck. They are divided according to function into motor and sensory. Some of the nerves communicate with the brain by more than one root, and in such cases the same nerve may have sensory fibers in one root and motor fibers in another. For example, the trigeminal nerve transmits a stimulus causing the muscles of mastication to contract and also supplies the teeth with sensory fibers (Fig. 90). The olfactory, optic, auditory and glossopharyngeal are the only cranial nerves wholly sensory. The oculo- motor, patheticus or trochlearis, abducens, facial, spinal accessory, and hypoglossal are wholly motor. ‘The trigeminal and pneumogastric contain both motor and sensory fibers. The dissection of the cranial nerves is very difficult. A head, containing a brain hardened by a formalin in- jection, should be placed in 500 c.c. of 5% nitric acid, which will decalcify the bone in about a week. After washing out the acid by soaking the specimen in running water twenty-four hours, the dissector may with much care follow the course of the nerves peripherad from their origin at the base of the brain. The vagus nerve must of course be traced in an entire specimen, where it may be easily followed in the neck region along with the carotid artery, whence it passes to the lungs and stomach (Fig. 64). Some of the sensory nerve roots bear ganglia, the largest of which is the Gasserran ganglion, more than a half centimeter in diameter, forming a knot on the sensory root of the trigeminal, within the cranial cavity (Fig. go). The Spinal Nerves.—There are forty pairs of nerves connected with the spinal cord. They issue from the vertebral canal through the intervertebral foramina. THE NERVOUS SYSTEM. 210 Each nerve is connected to the cord by a ventral and dorsal root (Figs. 90 and 98). ‘The former is also known as the motor root, since its fibers are almost entirely motor, while the latter is the sensory root, as it is com- posed of fibers transmitting impulses to the central nervous system. A ganglion about the size of a pin- head is located on the dorsal root immediately proximad of its junction with the ventral root, within the inter- vertebral foramen. This anatomy can be displayed by cutting away the dorsal muscles on either side of the column, and then, with the bone-cutters, severing the laminz of several of the arches of the vertebre, so that the roof may be removed from the vertebral canal (Fig. 22 3 Immediately beyond the intervertebral foramen each nerve gives off a dorsal branch to the muscles of the back, and a small connecting twig to the sympathetic system. The main nerve is then spoken of as the ventral branch. ‘These main nerves or ventral branches, in various regions of the trunk, anastomose with each other, forming plexuses. In the region of the neck there is formed the cervical plexus; in the region of the shoulder, the brachial plexus; in the region of the loins, the /umbar plexus; and in thé region of the sacrum, the sacral plexus (Figs. ror and 102). There are eight cervical nerves, the first of which does not make its exit through the intervertebral foramen, as do all the other spinal nerves, but traverses a foramen in the atlas. The first five cervical nerves, the three _ posterior cranial nerves, and branches from the sym- pathetic trunk, form the cervical plexus. ‘These five cervical nerves supply mainly the structures of the neck. dinere are thirteen pairs of thoracic nerves. “The ventral branches of the sixth, seventh, and eighth cervical 220 ELEMENTS OF MAMMALIAN ANATOMY. nerves and the first thoracic nerve form the brachial plexus. This may be displayed by removing the cephalo- humeral muscle and cutting through the pectoral muscles ,AAA } \ 4 ee a A SS x Ks ; es re mS k te 4 . \ SS a it oa Fic. 101.—VENTRAL ASPECT OF THE BRACHIAL PLEXUS AND CHIEF NERVES OF THE ARM. 6, 7, 8, and 1, Sixth, seventh, and eighth cervical and first dorsal nerves; ’ at, ath, anterior thoracic nerves; a and b, to muscles of the forearm; c and d, to the joint; cx, circumflex nerve; cu, internal cutaneous; de, to the deltoid; g, to the digits; f, to the digits; fo, supracondyloid foramen; /t, long thoracic; mc, musculocutaneous; me, median nerve; pt, posterior interosseous; pth, posterior thoracic; sp, musculospiral ; sp, to suprascapular region; sb, to subscapular region; ex, subscapular; ra, tadial; wn, ulnar nerve. THE NERVOUS SYSTEM. 220 about two centimeters from their origin (Fig. 47). The manner in which the nerves anastomose varies some- what, but the following will be found approximately COrrect: The sixth cervical nerve gives off a small branch to the rhomboideus and levator anguli muscles of the shoulder, and then divides into two nearly equal branches, one of which supplies the muscles on the lateral aspect of the scapula, and the other joins with the seventh cervical nerve. Small branches from the fifth and sixth cervical nerves unite to form the phrenic nerve supplying the diaphragm. The seventh cervical nerve gives off three small branches at about the same point, one of which is the posterior thoracic supplying the serratus magnus muscle, a second helps to form the musculocutaneous, and the ‘third forms part of the median and anterior thoracic. The main portion of the seventh cervical unites with the eighth and first thoracic, to form the musculospiral nerve. The circumflex and subscapular branches supplying the deltoid and subscapular muscles are also derived from the seventh. The eighth cervical nerve, after giving off a small branch to the pectoral muscle, a small twig to the median nerve, and a large branch to the first thoracic nerve, is continued as the main part of the musculospiral nerve. The first thoracic nerve gives first a large branch to the musculospiral nerve, a second small branch to the anterior thoracic, and a third branch forming the internal cutaneous nerve supplying the skin of the arm and forearm on the caudal aspect. The main portion of the first thoracic nerve then continues as the main part of the ulnar nerve. The nerves of the forelimb are five in number (Fig. 222 ELEMENTS OF MAMMALIAN ANATOMY. ror): the external cutaneous, the internal cutaneous, the musculospiral, the median, and the ulnar. The external cutaneous arises from the sixth and seventh cervical nerves and passes distad along the caudal aspect of the biceps to the cephalic aspect of the forearm, where it becomes subcutaneous. It supplies the biceps and coracoid muscles and the skin of the forearm. ‘The internal cutaneous arises from the first thoracic and passes along the ventral side of the arm, becoming subcutaneous just proximad of the elbow, where it is distributed to the skin of the arm and forearm on the caudal and ventral aspects. The musculospiral arises from the seventh and eighth cervical and first thoracic nerves. It is the largest component of the brachial plexus. It winds obliquely around the humerus to the cephalic aspect, where it divides into two branches, the radial and the posterior interosseous. ‘The radial nerve is the smaller and be- comes subcutaneous near the elbow, and passes along the radial region. The posterior interosseous proceeds along the dorsal aspect of the forearm to the wrist, where it divides into branches supplying the digits. The median nerve arises from the seventh and eighth cervical and first thoracic. It follows the course of the brachial artery, passing through the supracondylar foramen to the elbow, where it passes beneath the pro- nator teres to the carpal region, and supplies the first, second, and third digits. It also supplies the pronator teres and flexor muscles of the forearm. The ulnar nerve (Fig. tor) is derived from the eighth cervical and first thoracic. It courses with the brachial artery to the middle of the humerus, where it turns caudad to pass between the olecranon process and internal condyle of the humerus. It is here sub- THE NERVOUS SYSTEM. 223 cutaneous and furnishes the sensation experienced when one strikes what is popularly called his “funny bone,”’ but what is really the ulnar nerve. It then passes down the ulnar side of the forearm, supplying some of the flexor muscles, and finally divides to supply the fourth and fifth digits. The ventral: branches of the remaining thoracic nerves encircle the body, supplying the muscles and skin of those regions. The lumbar plexus (Fig. 102) is composed of the anastomosing of the ventral branches of the seven lumbar nerves. As in the cervical and thoracic nerves, the lumbar nerves divide into dorsal and ventral branches immediately without the intervertebral foramen. The former supply the muscles and skin of the back. The first five ventral branches are joined to each other by a delicate nerve-cord. In order to display this plexus, the entire ventral and lateral abdominal wall should be cut away and the specimen securely nailed to the tray on its back. ‘The adipose tissue and muscles lying on either side of the bodies of the lumbar vertebre must be carefully picked away until the roots of the nerves are apparent. They may then be easily followed distad. The tlohypogastric nerve is the ventral branch of the first lumbar nerve. It supplies the muscles of the abdomen. This nerve and the two next described are scarcely as large in diameter as an ordinary pin. The tlio-inguinal nerve is the ventral branch of the second lumbar nerve. Within two centimeters of its origin it divides into two branches, the cephalic of which supplies the rectus and transverse muscles and the caudal supplies structures in the inguinal region. The lumbo-inguinal nerve is the ventral branch of the third lumbar nerve. Its cephalic branch supplies the 224 ELEMENTS OF MAMMALIAN ANATOMY. lumbar region and its caudal branch is distributed to the superficial structures of the inguinal region. The fourth lumbar nerve divides into two parts, one of which is the external cutaneous nerve, supplying the skin and other structures of the hip region, and the other is the external spermatic, supplying the external genital organs. The anterior crural nerve is composed mainly of branches of the fifth and sixth lumbar. It receives a small branch from the fourth. It supplies the psoas muscles, which © it pierces, and then divides into several branches, one of which is the saphenous, passing subcutaneously along the mesal aspect of the leg. The other nerves supply the muscles of the thigh on the cephalic and mesal aspect. The obturator nerve is composed of branches from the sixth and seventh lumbar. It is smaller than the preceding, and passes through the obturator foramen to supply the obturator and adductor muscles. The great sciatic nerve is composed mainly of the ventral branches of the seventh lumbar and first sacral nerves. It usually receives accessions from the other sacral nerves and the sixth lumbar. The great sciatic is the largest peripheral nerve in the body. It passes caudad from its origin around the greater sciatic notch and thence along the caudal aspect of the thigh to the popliteal space, where it divides into the zternal and external popliteal nerves. ‘The former continues down the caudal side of the tibia as the posterior tibial nerve to the internal malleolus, where it divides into znternal and external plantar nerves, which supply the digits. The external popliteal or peroneal nerve extends to the outer cephalic aspect of the leg, where it divides into the musculocutaneous and anterior tibial nerves. ‘The former extends between the extensor longus digitorum and peronei muscles to its ramification on the dorsum THE NERVOUS SYSTEM. 225 Fic. 102—VENTRAL ASPECT OF THE NERVES OF HIND-LIMB. 4, 5, 6, 7, 1, 2, and 3, Fourth, fifth, sixth, and seventh lumbar, and first, second, and third sacral nerves; a, branch from the fourth to the fifth; ac, anterior crural; cu, saphenous; d, anterior tibial; e, peroneal or musculocutaneous; ex, external popliteal or peroneal; ef, external plantar; jo, obturator foramen; gs, greater sciatic; g, external sper- matic; 2, internal popliteal; 7p, internal plantar; kn, knee; /, external cutaneous; /s, lumbosacral cord; ¢, posterior tibial; s, small sciatic. 19 226 ELEMENTS OF MAMMALIAN ANATOMY. of the foot. It supplies the skin along its course and the peronei muscles. The anterior tibial nerve passes down on the cephalic aspect of the tibia beneath the extensor longus digitorum muscle to the tarsal region, where it anastomoses with a branch of the external cutaneous, and supplies the skin, tibialis anticus, and the extensor muscles. The lesser sciatic nerve is a branch of the greater sciatic in the buttock region. The pyriformis, obturator, gemelli, quadratus femoris, semitendinosus, and semi- membranosus muscles are innervated by the greater sciatic nerve (Figs. 48 and 102). The sacral plexus is an irregular network cone eed of the ventral branches of the three sacral nerves and two or more small twigs from the seventh lumbar (Fig. 102). This plexus is seldom the same in any two cats. From it are given off the internal pudic and glutei nerves. The former supplies the prostate and anal glands, the sphincter muscle, and the penis. The latter supplies the glutei and pyriformis muscle. THE SYMPATHETIC NERVOUS SYSTEM. The sympathetic nervous system is composed chiefly of a pair of nerve-cords extending from the base of the skull to the root of the tail, a number of ganglia and branches supplying the thoracic and abdominal viscera, and numerous minute fibers supplying the muscular walls of the blood-vessels in all parts of the body. The sympathetic system supplies all non-striped or involun- tary muscles in any part of the body. In order to: demonstrate this system successfully, one should use a lean injected specimen. After the cat has been securely nailed on its back to the tray, the entire THE NERVOUS SYSTEM. 227 ventral half of the thoracic and abdominal walls should be removed. By pushing the heart and lungs to the left side a white cord about one millimeter in diameter may be seen lying near the median dorsal line (Fig. 103). The left cord may be found in a similar manner and both followed cephalad and caudad, noting their numer- ous branches in accordance with the following descrip- tion. . The sympathetic nerve=cord begins in the superior cervi- cal ganglion lying near the arigle of the mandible, beneath the submaxillary and lymphatic glands. This ganglion is about the shape of a grain of wheat, but not more than half so large, and is adjacent to the small vagus ganglion on the dorsal side of the carotid artery. The ganglia are masses of large nerve cells and occur at regular intervals on the sympathetic cords in the body cavity, and are present also on some of the branches of the cords (Hig. 104). On the cords there are three pairs of cervical ganglia, thirteen pairs of thoracic ganglia, seven pairs of lumbar ganglia, and one or two pairs of sacral ganglia, in addition to two median unpaired sacral ganglia. In the cervical region the sympathetic and pneumo- gastric, or tenth cranial nerve, are bound in a common sheath lying along the lateral aspect of the carotid artery. One or two centimeters cephalad of the first rib is the thyroid or middle cervical ganglion, whence the nerve proceeds in two cords, enclosing the subclavian artery, to the large inferior cervical ganglion just caudad of the first rib. From the cervical portions of the sym- pathetic cord are given off numerous delicate branches, forming the carotid plexus on the carotid artery, and uniting with the eight posterior cranial nerves and the first spinal nerve. From the inferior cervical ganglion 228 ELEMENTS OF MAMMALIAN ANATOMY. a branch goes to the vagus nerve, several branches to the brachial plexus, and a branch to the heart, form- ing the cardiac plexus, while the main sympathetic cord continues along the dorsal thoracic wall. A ganglion occurs opposite each verte- bral body, from which it gives off a branch to the corresponding spinal nerve. The great splanchnic arises from the main cord just cephalad of the diaphragm and extends to a group of ganglia in the region of the trunk of the cceliac axis Fic. 103.—CHIEF PART OF LEFT HaLF OF SYMPATHETIC SYSTEM CEPHALAD OF THE DIAPHRAGM. Semidiagrammatic. 5, 6, 7,. 8, 9, and 10, Futth,, sixth, seventh, and eighth cervical nerves, and first and second thoracic spinal nerves; a, the dorsal branch of the left vagus ln; an, dorsal branch of the right vagus; ax, common dorsal vagus formed by a and an; avb, ventral vagus ; bc, cardiac branch of sg, cr, carotid plexus; car, carotid ar- tery ;cm,ramicommunicantes ;cp, cardiac plexus; dia, diaphragm; g, ganglia in the thoracic cavity; zg, middle cervical ganglion; /g, portion of left lung; Jn, left vagus nerve; nv, cranial nerve; pn, phrenic nerve; pf, pulmonary plexus ; sn, sympathetic cord; sm, superior cervical ganglion; sb, left ' subclavian artery; sg, stellate ganglion or inferior cervical; spm, splanch- nic major nerve; vg, vagus ganglion; v, vagus nerve. THE NERVOUS SYSTEM. 229 (Figs. 103 and 104). These ganglia and anastomosing branches constitute the solar or epigastric plexus, lying Fic. 104.—CuIeF PART oF LEFT HALF OF SYMPATHETIC SYSTEM CAUDAD OF THE DIAPHRAGM. Semidiagrammatic. bl, Bladder; ce, coeliac axis; du, duodenum cut off; dia, diaphragm; gr, anterior gastric plexus; g, ganglion; 7m, inferior mesenteric artery; a, external iliac artery; ng, dorsal branch of vagus (Fig. 103, ax); nl, ventral branch of vagus; oe, esophagus cut off; p, superior mesen- teric plexus; plx, inferior mesenteric plexus; px, branches to dorsal gastric plexus; rn, renal plexus; sm, superior mesenteric artery; spn, splanchnic major or greater splanchnic nerve from the sympathetic cord; sg, semilunar ganglion; spc, sympathetic cord of left side. dorsad of the stomach, to which it sends numerous branches. ‘This plexus also receives the lesser splanchnic nerve coming from the sympathetic cord just cephalad 230 ELEMENTS OF MAMMALIAN ANATOMY. of the diaphragm, and branches from the tenth cranial nerve. The largest ganglion of the solar plexus is the semz- lunar. ‘The solar and its allied plexuses send nerves to the diaphragm, suprarenal bodies, many of the blood- vessels of the abdominal cavity, stomach, kidneys, ureters, testes or ovaries, uterus, liver, gall-bladder, spleen, pancreas, and intestines. The hypogastric plexus is the third great sympathetic plexus. It lies on the ventral aspect of the two caudal lumbar vertebre and is formed by branches from the solar plexus and a few twigs from the sympathetic cords. It supplies the blood-vessels of the pelvic region and all the organs of the pelvis. The sympathetic cords in the lumbar region lie near together and the com- municating branches between them and the spinal nerves are longer than in the thoracic region. In the sacral region there are no rami communicantes, and the ganglia are irregularly arranged. A median ganglion in the sacral region is known as the ganglion impar. There may be two median ganglia. The sympathetic cords terminate in the tail. PRACTICAL QUESTIONS AND SUGGESTIONS. 1. Name the foramina of the skull giving passage to one or more cranial nerves. 2. From a study of one or more specimens and the description in the book make a diagrammatic drawing of each cranial nerve. 3. Which cranial nerves have their roots in the medulla? 4. Name the cranial nerves which are wholly motor. 5. Which of the cranial nerves do not supply structures of the head? 6. Of what are ganglia composed? 7. Make a drawing of your dissection showing the connection between the spinal and sympathetic nerves. 8. Which spinal nerves form the several plexuses? 9. Make a drawing showing wherein the brachial plexus in your specimen differs from that described in the text. THE NERVOUS SYSTEM. 231 10. Write a description of your dissection of the nerves of the thoracic limb. 11. Mention in what way the lumbar plexus differs from the descrip- tion in the book. : 12. Draw the great sciatic nerve and its branches as seen from the caudal aspect. 13. What nerves supply the digits? 14, Describe the chief plexuses of the sympathetic system. 15. How do stimuli from the viscera reach the brain? 16. What portion of the body is not supplied with nerves from the sympathetic system? THE ORGANS OF SENSE. The organs of sense are the specialized peripheral terminations of the sensory nerves, and are so constructed as to be capable of receiving only a certain kind of stimulus. The stimuli for the eye are ether vibrations; those for the ear are vibrations of the air. The stimu- lation of the sensory nerves produces sensations in the cells of the cerebral cortex to which they lead. The external stimuli giving rise to the internal sen- sations of seeing, hearing, smelling, and tasting are transmitted by only four pairs of cranial nerves, while the stimuli of cutaneous sensations are transmitted by three pairs of cranial nerves and all the spinal nerves. Cutaneous Sense Organs.—The cutaneous sense organs are composed of the endings of the sensory nerves in all parts of the skin and the mucous membrane of the mouth, nose, arms, vagina, and urethra. One kind of sense organs, those of pain, are present in every organ of the body. The sense organ of pain is probably an unmodified free nerve-ending. While all portions of the skin and perhaps other parts of the body are supplied with organs capable of receiving stimuli giving rise to tactile sensation, the soles of the feet and the skin at the base of the vibrissz 232 ELEMENTS OF MAMMALIAN ANATOMY. are specially sensitive regions. The nerves terminate in a kind of wreath formation about the base of the vibrisse. All of these sense organs are invisible to the naked eye except the Pacinian corpuscles, whose function is unknown. If the mesentery is held up and looked through toward the light, the Pacinian corpuscles or sensory nerve terminations appear as translucent oval bulbs about two millimeters long. If a piece of the mesentery containing a corpuscle is pinned tense on a piece of cork and then cut out and placed ten minutes in 3% acetic acid, the termination of the nerve within the corpuscle may be seen with a microscope magnifying thirty diameters. All the spinal sen- sory nerve fibers enter the cord by the posterior root (Figs. 90 and 96). Fic. 105. — Pactnian The Olfactory Organ.—The organ of Kee Mescwiere » smell lies in that part of the mucous 20. membrane lining the caudal part of ope ‘une the nasal cavity and the basal third of white substance of the ethmoturbinal bones (Fig. 18). Schwann; e, epithe- lial cell. That part of the mucous membrane containing the olfactory cells is known as the Schneidertan membrane. Ina fresh specimen it is of a grayish color while the other mucous membrane is red. ‘The first pair of cranial nerves convey the olfactory impulse to the brain. They pass through the foramina in the cribriform plate of the ethmoid bone, to the olfactory bulbs, from each of which two roots extend to the base of the cerebrum (Fig. 90). The Gustatory Organ.—The organ of taste is located chiefly in the mucous membrane on the dorsum of the THE NERVOUS SYSTEM. 223 tongue, the soft palate, the pillars of the fauces, epi- glottis, and part of the cheek. On the dorsum of the tongue are seen four kinds of papille—the circumvallate, the fungiform, the filiform, and flat. The circumvallate papillz are from eight to twelve in number, forming two sides of a’ triangle on the caudal portion of the dorsum of the tongue. ‘The fungiform are blunt papille scattered sparsely in the midst of the numerous filiform or pointed papille (Fig. 55). The special organs of taste, known as taste-buds, are very numerous in the fungiform and circumvallate papilla of most mammals, but in the cat they are few and not well differentiated. These taste- buds occur in many parts of the mucous membrane of the mouth cavity, each being supplied with a branch of the glossopharyngeal nerve. The Visual Organ.—The special organ of sight is the eye, which occupies the orbital cavity of the skull. The ball of the eye is protected above and below by extensions of skin called the eyelids or palpebre, which are lined with mucous membrane, a transparent layer of which, known as the conjunctiva, extends over the front of the eyeball between the two lids. The dorsal lid is raised by the levator palpebre muscle, which has its origin in the occipitofrontalis muscle. A sphincter _ muscle, the orbicularis palpebrarum, lies on the margin of the lids, and by its contraction closes the eye. The point on either side where the two eyelids meet is termed the canthus or angle. At the mesal or inner canthus are two minute apertures, the puncta lachry- malta, leading into two short canals which unite to form the nasal duct. ‘The lachrymal canal, which forms the channel for this duct, is clearly visible in the lach- rymal bone of the dried skull. At the mesal canthus there is a prominent fold of mucous membrane, the 20 234 ELEMENTS OF MAMMALIAN ANATOMY. membrana nictitans, or plica semilunaris, which is a rudimentary structure in the cat, but is found well developed in birds, which have the power of sweeping it rapidly across the eyeball, thereby removing dust. On the inner surface of each lid are the Mezbomian glands. The lachrymal gland lies in the dorso-lateral region of the orbit, and its ducts open on the ventral surface of the upper lid, whence the tears flow over the conjunctiva ventrad to the puncta lachrymalia. The Harderian gland is the very small gland at the mesal canthus. The muscles controlling the movements of the eye- ball are seven in number: four are recti muscles, two are oblique, and one is a retractor. The recti muscles (Fig. 90) originate on the bone around the optic for- amen, and are inserted on the sclerotic coat, caudad of the equatorial ring. The external rectus is inserted on the lateral aspect; the internal rectus, on the mesal aspect; the superior rectus, on the dorsal aspect; and the inferior rectus on the ventral aspect. The superior oblique muscle arises from the sphenoid bone mesad of the optic foramen, extends along the mesal wali of the orbital cavity to its dorso-mesal margin, where it passes through a tendinous loop fastened to the frontal bone and then turns laterad to its insertion in the sclerotic beneath the superior rectus. The inferior oblique arises from the lachrymal bone and is inserted on the sclerotic between the external and inferior recti muscles. The above muscles may be demonstrated by cutting away the lateral and dorsal walls of the orbital cavity. The retractor oculi originates on the boundary of the optic foramen and is inserted into the sclerotic around the entrance of the optic nerve. This muscle is completely hidden by the recti muscles, THE NERVOUS SYSTEM. 230 The eyeball is composed of three membranes and three humors. The outer coat, the sclerotic, consists of the opaque portion forming the caudal two-thirds, and the transparent portion, or cornea, forming the Pimameer (hig, 106).) Lhe optic merve pierces. the sclerotic a little mesad of the longitudinal axis of the eye. The surface of the cornea is more strongly curved than that of the opaque portion of the sclerotic, and Fic. 106.—LONGITUDINAL SECTION OF THE EYE. aq, Aqueous humor; c, cornea; cp, capsule of the lens; ch, choroid; cz, ciliary process; 2, iris; /g, ligament of lens; m, ciliary muscle; opn, optic nerve; rt, retina; sc, sclerotic coat; os, ora serrata. contains no blood-vessels. The second or middle coat of the eye is formed by the choroid membrane and its extension, the iwvis. This coat is incomplete, as there is an aperture, the pupil, through the iris for the ad- mission of light. The choroid appears as a jet-black membrane, less than half as thick as the sclerotic, lying closely appressed to the latter. The choroid is lined internally by dark pigment cells, except in the caudal area around the optic nerve, which has a metallic luster. 230 ELEMENTS OF MAMMALIAN ANATOMY. This portion is called the tapetum. It causes the shining appearance of the cat’s eyes in the dark. The choroid is a vascular membrane, being supplied by the ophthalmic artery, a branch of the internal carotid. The iris is attached by its peripheral margin to the sclerotic and choroid coats, and hangs free in the aqueous humor. It .gives color te the eye. dn ‘ihe eat aise yellowish, while in man it is frequently blue or black. The iris is merely a curtain to regulate the amount of light admitted to the retina. There is a sphincter muscle lying in it, which by contraction renders the pupil very small. There is probably no dilating muscle of the iris present in the cat. The short,, thickened, radial projecting folds of the choroid are the czlary processes, which contain numerous blood-vessels, and in some mammals a gland. ‘The ciliary muscle arises from the sclerotic coat near its junction with the cornea, and is inserted into the cephalic part of the choroid coat. The inner membrane of the eye is the retina, which is of a light gray color in a fresh specimen and seems quite free from the choroid... It is thickest’ m ‘the. caudal two-thirds of the cavity of the eyeball (Fig. 106). At the base of the ciliary bodies it seems to end with a free margin, called the ora serrata. In reality it becomes very thin here and is prolonged over the ciliary bodies and covers the caudal aspect of the iris. The blind spot is the point of entrance of the optic nerve, laterad of which is the yellow spot, or macula lutea, containing the fovea centralis, or acute point of vision. This is the point on which the rays of light are focused when the cat sees distinctly. The three humors of the eye are the aqueous, the crystalline lens, and the witreous humor. The aqueous humor is a watery fluid occupying the anterior chamber THE NERVOUS SYSTEM. 2 te, between the cornea and crystalline lens. It always escapes as soon as the cornea is punctured. The vitreous humor is of a jelly-like consistency, filling the large pos- terior chamber caudad of the lens. It is perfectly trans- parent and is surrounded by a Shs capsule, the hyaline membrane. The crystalline lens is a transparent picorser tissue having a vertical diameter of about one centimeter and a shorter diameter through its optical axis. It is enclosed in a transparent elastic capsule, some of whose fibers are continued peripherad as the suspensory ligament which is inserted in the choroid coat (Fig. 106). The Auditory Organ.—The organ of hearing is com- posed of three parts—the external ear, middle ear, and internal ear. The first consists of the pinna and the auditorius meatus externus. The pinna is the pro- jecting portion of the ear capable of being moved by muscles, and is composed of integument strengthened by fibrocartilage. The auditorius meatus externus ex- tends from the base of the pinna to the tympanic mem- brane (Fig. 107). Its outer or lateral third is formed by cartilage, and the remainder by the tympanic por- tion of the temporal bone (Fig. 17). The meatus is lined with mucous membrane in which are numerous sebaceous and oleaginous glands. The latter secrete the wax of the ear. The middle ear, or tympanum, is an irregular cavity about one centimeter in diameter contained in the lateral chamber of the bulla (Fig. 107). It is separated from the external auditory meatus by the delicate translucent membrane, the membrana tympam. The petrous bone containing the internal ear forms part of the inner or nasal wall. In the petrous bone are two foramina which may be seen in a dry skull by looking 238 ELEMENTS OF MAMMALIAN ANATOMY. through the external auditory meatus. The more dor- sal foramen is the fenestra ovalis, which in the recent state is closed by a membrane to which the foot of the stapes is attached. The ventral one is the fenestra rotundum, also closed by a membrane in the recent state. In the dry skull the fenestra ovalis opens into the first or basal whorl of the cochlea, and the fenestra rotundum opens into the vesti- bule of the internal ear. The Eustachian tube (Fig. 18), whose opening may be seen cephalad of the auditory bulla, connects the middle ear with the posterior nares and thus admits air to the tympanic cavity. To demonstrate further the J Fic. 107.—DIAGRAM OF THE MAMMALIAN EAR. The internal ear is repre- sented removed about a centimeter from the mid- dle ear and slightly rotated to the left. The base of the stapes, s, in nature, covers the fenestra ovalis, ov; c, basal whorl of the cochlea ; ea, external auditory meat- us; eu, opening of the Eu- stachian tube; z, incus; 77, malleus; sc, semicircular canals; ve, vestibule; 1, tympanum. anatomy of the middle ear, one should clean the flesh from a fresh or preserved head and care- fully cut away the ventral walls of both chambers of the auditory bulla (Fig. 17). In the middle ear ate “tiiree bones, the malleus, incus, and stapes, commonly called ham- mer, anvil, and stirrup. They form a crooked chain across the cavity. The long process of the malleus is fastened throughout nearly its whole length to the inner or mesal surface of the membrana tympani, and its enlarged extremity articulates with the body of the incus. The latter has two legs, to one of which the stapes is attached. The base of the stapes is inserted in the membrane closing the fenestra ovalis (Figs. 17 and 107). THE NERVOUS SYSTEM. 239 The znternal ear, or labyrinth, consists of three parts— the vestibule, cochlea, and semzcircular canals (Figs. 18 and 107). All of these parts are of membrane and lie in cavities of corresponding shape within the petrous bone. A lymphoid fluid, the perilymph, floats the deli- cate membranous internal ear within its bony cavity, while within the membrane is a similar fluid, the endo- lymph. ‘The vestrbule is a small sac adjacent to the tympanum, and may be seen by looking through the Fic. 108.—SECTION OF THE Goes OF THE CALF. xX 10.—(From Ellenberger, ajter K6élliker.) a, Modiolus; c, scala tympani; v, scala vestibuli; /m, lamina spiralis; pt, portion of the petrous bone; 7, scala media, or ductus cochlearis. fenestra ovalis. From the dorso-caudal aspect of the vestibule, arch three semicircular canals at nearly right angles to one another. The external semicircular canal is in a horizontal plane and surrounds a small fossa almost caudad of the fenestra ovalis. The superior semicircular canal lies in a transverse plane caudad to the preceding. The posterior semicircular canal lies in a vertical longitudinal plane, immediately laterad from the jugular foramen. The cochlea is a coiled canal lying within the beter 240 ELEMENTS OF MAMMALIAN ANATOMY. cavity, the bony cochlea, extending cephalad from the vestibule. If both chambers of the auditory bulla are removed and a bristle thrust into the fenestra rotundum (Fig. 17), it will enter the basal whorl of the bony cochlea. A line drawn from the lateral margin of the foramen ovale to the mesal margin of the fenestra rotundum passes through the apex and middle of the base of the cochlea, which may be rendered visible by carefully clipping off with the bone-forceps the ventral portion of the petrous bone along the line indicated. This coiled canal, the cochlea, is divided into two channels by a shelf of bone, the lamina spiralis, projecting from the central axis or modiolus of the coil (Fig. 109). The bony lamina extends but partly across the canal, the remaining distance being bridged by membrane. ‘The cephalic channel, or the one nearer the apex of the cochlea, is called the scala vestibuli. The other is the scala tympani. The semicircular canals probably have nothing to do with hearing, as they are well developed in fishes, which do not hear at all. They may aid in helping the cat to maintain its equilibrium. The auditory nerve, how- ever, is distributed to the vestibule and semicircular canals as well as to the cochlea upon the lamina spiralis, where the organ of Corts, the essential organ of hearing, is located. REMARKS ON THE MAMMALIAN NERVOUS SYSTEM. So far as known, the relation of the sympathetic to the peripheral and central nervous systems is the same in all mammals. The number of spinal nerves varies with the number of vertebre. The distribution of these nerves, however, is approximately the same in all forms THE NERVOUS SYSTEM. 241 with five digits. In those having a less number of digits the nerve branch corresponding to the lacking digit or digits is wanting. The arrangement of the columns or tracts of fibers in the spinal cord is very similar in all the orders. The anterior or direct pyramidal tract, however, is absent in most orders below the Primates. It is best developed in man, although in a number of cases it has been found entirely wanting in the human. The number of the cranial nerves is always twelve and their distribution is the same in all forms investigated. The structure of the brain in the Ornithodelphia and Didelphia differs considerably from that of the Mono- delphia. In the two former subclasses the corpus - callosum and fornix are very rudimentary, but the anterior commissure piercing the corpora striata is un- usually large. The fibers, which in the Monodelphia arise from the cells of the hippocampus, and extend cephalad to form the fornix, cross transversely to the opposite hippocampus in the two lower subclasses. In all higher mammals the cerebrum is greatly con- voluted, but in the lower ones the convolutions are few or almost absent, as in Ornithorhynchus. The above-mentioned features show that the ornithodelphian brain presents a striking similarity to the brains of reptiles and birds. The brains of Rodentia possess but few convolutions, while the brain of man is the most highly convoluted. The size of the brain varies widely. As a rule, the larger the brain in proportion to the size of the animal, the greater is its intelligence. However, in man this statement does not hold true, as an individual with a small brain may be much more capable mentally than one with a large brain. Mental power in man seems to depend upon the development of the cells and fibers of the brain. 242 ELEMENTS OF MAMMALIAN ANATOMY. The average weight of a male human brain is about three pounds; of a female, about two and two-thirds pounds. The human brain is 2; the weight of the body; the ape’s, ;45; the rat’s, 4,; the sheep’s, ;1,; and the ele- phant’s,;4+,. The brain of man is larger than that of any other mammal except the whale and elephant. The brain of a large whale weighs over four pounds, while that of a large elephant will weigh about ten pounds. PRACTICAL QUESTIONS AND SUGGESTIONS. 1. How many nerves transmit the stimuli received by the organs of special sense? 2. Where are the sense organs of pain located? ; : 3. How many sense organs are visible in the mesentery of your specimen? 4. Describe the path of a stimulus from the index finger to the brain. 5. Through which nerve roots would the stimuli received by the cutaneous sense organs pass into the cord? 6. Describe the nerves transmitting the stimuli from the olfactory organ. 7. Describe the gland secreting the tears and how they reach the nasal cavity. ; 8. By cutting away the lateral and dorsal walls of the orbit dissect the muscles of the eyeball and make a drawing of them, labeling all parts. 9. What nerves control the movements of the eyeball? 10. Procure the eyes of any mammal from the butcher-shopor slaughter- house; bisect one in the meridional and the other in the equatorial direc- tion. Make a drawing of the features seen and label. 11. Remove the crystalline lens from a fresh eye, describe its size, shape, structure, length of focus, and power of magnification. 12. Describe the path of a stimulus from the retina to the area of sight in the brain. 13. Name every feature visible in the eyes you have dissected. 14. What nerve supplies the auditory organ? 15. Describe the middle ear. 16. In what part of the temporal bone is the internal ear located? 17. By looking into the auditorius meatus of the dried skull two open- ings are seen. Into which portions of the internal ear do these lead? 18. Write a description of the internal ear. 19. Mention some important points of difference in the nervous system of various mammals. 20. What relation, if any, between intellectual ability and brain devel- opment? INDEX. A. Abdominal aorta, 144 arteries, 145 cavity, 125 muscles, 104, 106 veins, 154 Accessory glands, 131 Acetabulum, 79, 81 Adipose tissue, 33 Air sacs, 172 Alcohol as a preservative, 27 Alimentary canal, 124 length of, in mammals, 137 Alveoli, 172 Amphiarthroses, 89 Amphibia, 19 Anesthetization, 21, 22 Anatomy, 17 Anterior perforated space, 191 Aorta, 143 Aponeuroses, 95 Aqueduct of Sylvius, 193 Arachnoid, 186, 205 Arbor vite, 203 Arm, arteries of, 148 bones of, 67 muscles of, 100 nerves of, 222 Arteries, 143 abdomen, 144 arm, 148 brain, 146 injection of, 20 leg, 151 neck, 145 thorax, 143 valves of, 154 Artery, adrenolumbalis, 145 anastomotica magna, 150 axillary, 148 basilar, 146 brachial, 148, 150 Artery, bronchial, 144 243 carotid, 143, 146 cerebellar, 146 cerebral, 146 circumflex anterior, 150 ceeliac, 144 coronary, 143, 145 epigastric, 151 femoral, 151 anterior, 151 posterior inferior, 152 superior posterior, 151 | hepatic, 144 iliac, 145 iliolumbar, 145 inferior alveolar, 147 infraorbital, 147 intercostal, 148 interosseous, 150 lingual, 147 lumbar, 144 malleolar, 153 mammary, 148 maxillary, 147 meningeal, 147 mesenteric, 145 ophthalmic, 147 phrenic, 145 popliteal, 152 profunda, 151 superior, 150 pulmonary, 142- radial, 148, 150 renal, 145 saphenous, 152 spermatic, 144 subclavian, 143, 148 subscapular, 149 temporal, 147 thoracic, 149 thyroid, 147 axis, 149 tibial, 152 2AA INDEX. Artery, ulnar, 150 vertebral, 147 volar, 150 Articulation, 40 Arytenoid cartilage, 169 Association fibers, 215 Astragalus, 85, 86 Atlas, 57 Auditory bulla, 45 nerve, 240 organ, 237 Aves, 19 Axis, 59 Axis-cylinder process, 208 B. Basal ganglia, 198 ‘Bicuspid valve, 141 Bile, 134 Binomial nomenclature, 20 Bladder, 176 Blood-vessels, 143 injection of, 21 Body of vertebra, 59 Bone structure, 39 Bones, 41 ear, 238 head, 41 kinds of, 36, 38 pelvic limb, 79 preparation of, 27 sesamoid, 36 table of, 37 terms used in describing, 36, 38 thoracic limb, 67 Brachia, 199 Brachial plexus, 220 Brachio-cephalic artery, 143 Brachium conjunctivum, 201 Brain, 186 arteries of, 146 extefnal features, 187 fiber-tracts of, 213 fissures, 188 internal structure, 192 ventricles of, 197 Broad ligament, 136 Bronchus, 170 Buccal cavity, 117 C. Caleaneum, 85 Canalis centralis, 206 Canide, 19 Cannon bone, 76 Cannula, 21 Capillaries, 30, 159 Capsular ligament, 90 Cardiac plexus, 128 Carnivora, 19 Carotid artery, 143 Carpalia, 74 Carpus,’ 72579 Cartilage, 29 semilunar, 91 Caudad, 38 Caudal, 38 Cells, 28, 29 gastric glands, 129 Merve, 208 Central nervous system, 186 preparation for dissection, 26 Cephalad, 38 Cephalic, 38 Cerebellum, 203 Cerebrum, 188 Chevron bones, 62 Chief motor tract, 214 Choroid membrane, 235 plexus, 193 Cilia, 170 Circle of Willis, 147 Circulatory system, 140 Classes of vertebrates, 19 Classification of animals, 18 Clave, 202 Clavicle, 68 Claws, 34 Clinoid plate, 49 processes, 49 Clitoris, 178 Cloaca, 184 Coccyx, 63 Cochlea, 40, 239 Coeliac axis, 144 Colon, 128 Columns of spinal cord, 206 Commissures of brain, 194 Condyle, 39 Conjunctiva, 233 Connective tissue, 29 Convolutions of brain, 188 Coracoid process, 68, 69 Cornu Ammonis, 196 Corona radiata, 215 Corpora albicantia, 191 quadrigemina, 198 striata, 200 INDEX. Corpus callosum, 196 dentatum, 203 geniculatum, 199 Cotyloid bone, 79 Cranial nerves, 215 Cranium, 41 Cribriform plate, 43, 44 Cricoid cartilage, 169 Crossed pyramidal tract, 212 Crucial ligaments, 91 Crura cerebelli, 203 cerebri, 191 Crus, 83, 84 ad pontem, 203 Crystalline lens, 236 Cuboid, 86 Cuneiform, 74 Cutaneous sense organs, 231 Cystic duct, 134 D Deciduous teeth, 122 Decussation of pyramidal tract, 212 Dendrites, 208 Dentition, deciduous, 122 mammalian, 123 of cat, 120 Dermis, 33 Diarthroses, 89 Diastema, 55 Diencephalon, 187 Digestion, organs of, 117 Digestive system of mammals, 137 Digitigrade, 78 Digits, 76, 81, 86 Dissection, directions for, 95 Distad, 38 Distal, 38 Distribution, 18 Ductless glands, 165 Ductus communis choledochus, 128, 134 Duodenum, 126 Dura mater, 186, 205 E. Ear, 237 Ectocuneiform, 86 Embryology, 17 Endomysium, 93 Endoskeleton, 32 Entocuneiform, 86 Epidermis. 33 245 Epididymis, 182 Epiglottis, 169 Epimysium, 93 Epiphysis, 39 Epithelium, 28, 29 Esophagus, 126 Ethmoid bone, 42 Ethmoturbinal, 42, 44 Eustachian tube, 45, 124 Excretion, 30 Excretory system, 174 Exoskeleton, 32 External capsule, 201 Eye, 233 F. Face, 41 Falciform ligament, 133 Fallopian tubes, 177 Falx cerebri, 186 Families, 19 Fascia, 94 Fasciculus of Burdach, 211 of Goll, 211 of muscle, 94 Fauces, 117 Female organs, 177 Femur, 81 Fenestra ovalis, 45 rotundum, 45 Fiber tracts of nervous system, 210 Fibers, 29, 30 of brain, 213 Fibula, 84 Fillet, 215 Fissures of brain, 188 Foot, arteries of, 153 bones of, 85 muscles of, 109, 111 nerves of, 224 Foramen, 39 anterior palatine, 51 infraorbital, 52 intervertebral, 62 jugular, 48 lacerum, 48, 50 magnum, 46 mental, 55 obturator, 81 of Monro, 193 optic, 51 ovale, 51 Foramina, table of, 49 Formaldehyde, 20, 96 Fossa, 39 246 Frena, 119 Frontal bones, 41 Funiculi gracilis, 211 of Goll and Burdach, 211 Funiculus cuneatus, 202 of Rolando, 202 G. Gall-bladder, 126 Gall-eyst in mammals, 138 Ganglia, 218, 219, 227 Gasserian ganglion, 218 Gastric glands, 129 Genera, 19 Ginglymus, 90 Gland, Cowper’s, 183 lachrymal, 234 mammary, 180 parotid, 132 prostate, 183 salivary, 131 thymus, 166 thyroid, 166 Glands, accessory, 131 Harderian, 234 lymph, 162 Meibomian, 234 of mouth, 119 of small intestine, 130 of stomach, 129 sebaceous, 33, 174 sudoriparous, 34, 174 Glenoid cavity, 55, 67 Graafian follicle, 179 Great splanchnic nerve, 228 Gustatory organ, 232 Gyri of brain, 188 H. Habena, 200 Hair, 34 Haversian canals, 40 Heart, 140 Hepatic duct, 134 Hippocampus major, 196 Histology, 17 Horns of mammals, 41 Humerus, 69 Humors of eye, 236 Hymen, 178 Hyoid bones, 55 Hypogastric plexus, 230 Hypophysis, 191 INDEX. Ileum, 128 Ilium, 79 Infundibula, 172 Infundibulum, 191 Inguinal canal, 182 Injection of vessels, 20 Innominate bone, 79, 81 Integument, 33 Internal capsule, 201, 205, 212 malleolus, 84 Interparietal, 46 Intestine, 126 ins, 235 Ischium, 79 Iter or aqueduct of Sylvius, 193 13 Jar, preservation, 20 Jejunum, 126, 128 Joints, 89 K. Kidney of cat, 175 of mammals, 184 Knee-joint, 90 L Lachrymal bone, 53 Lacteals, 130, 161 “injection: ot, 25 Lacune, 40 - Lambdoidal ridge, 48 Larynx, 55, 168 Laterad, 38 Leswartermes of, tol bones of, 79 muscles of, 108 nerves of, 224 Ligaments, 29 of ‘knee-joint, 91 of larynx, 135 Linea aspera, 82 Liver, 133 Lumbar plexus, 223 Lungs, 172 Lymph, injection of, 24 system, 161 M. Malar bone, 54 gland, 132 Male organs, 180 INDEX. Malpighian bodies, 175 Mandible, 54 Marrow, 40 Marsupialia, 19 urogenital system of, 184 Mastoid portion of temporal, 45 Maxilla or maxillary, 52 Maxilloturbinal, 53 Meatus auditorius externus, 45, 237 internus, 46 Median nerve, 222 Mediastinum, 172 Medulla oblongata, 202 Membranes, mucous, 129, 137, 232 of brain, 186 of cord, 205 serous, 136 Meninges, 186, 205 Meniscus, 90 Mesad, 38 Mesal, 38 Mesencephalon, 187, 188 Mesenteries, 135 Mesethmoid, 43 Mesocuneiform, 86 Metacarpus, 75 Metatarsus, 86 Mitral valve, 141 Morphology, 17 Motor decussation, 213 Mouth, 117 Mucous membrane, 129, 137, 232 Muscles, dissection of, 95 eye oo head and neck, 97 kinds, 93 naming of, 94 pelvic limb, 108 table of, 97 thoracic limb, 100 Musculospiral nerve, 221 N. Names, scientific, of animals, 20 Nares, 124 Nasal bone, 53 chamber, 53 duct, 233 septum, 43 Navicular, 85 = Nerve, abducens, 217 anterior crural, 224 auditory, 217 facile 217. 247 Nerve, glossopharyngeal, 217 hypoglossal, 217 iliohypogastric, 223 interosseous, 222 lumbo-inguinal, 223 mandibular, 217 maxillary, 217 median, 222 musculocutaneous, 224 musculospiral, 220, 222 obturator, 224 oculomotor, 217 olfactory, 217 ophthalmic, 217 optic, 217 pathetic or trochlear, 217 peroneal, 225 phrenic, 228 plantar, 224 radial, 222 saphenous, 224 sciatic, 224, 226 splanchnic, 228 subscapular, 221 thoracic, 221 tibial, 224 trigeminal, 217 winar,222 vagus, 217, 228 Neural arch, 57 eanal, 59 Nomenclature, 20 | Nucleus caudatus, 201 cuneatus, 211 gracilis, 211 lenticularis, 201 O. Obturator foramen, 81 nerve, 224 Occipital bone, 46 Olfactory organ, 232 Omentum, 135 Ontogeny, 17 Optic commissure (chiasm), 191 195 nerve, 217 thalami, 199 Orbital plate, 52 Orders of mammals. 19 Organ, 28 of Corti, 240 Organs of sense, 231 Ornithodelphia, 19 248 Ornithodelphia, brain of, 241 urogenital system, 184 Os calcis, 85 magnum, 75 planum, 43 Osseous system, 31 Ova of mammals, 179 Ovaries, 178 Oviparous, 19 E. Pacinian corpuscle, 232 Palatine bone, 52 plate, 52 Pancreas, 135 Papille of tongue, 233 Parietal bone, 46 Parotid gland, 132 Patella, 83 ligaments of, 90 Peduncles of cerebellum, 203 of cerebrum, 191, 213 Penis, 183 Pericardium, 140 Perimysium, 94 Periosteum, 40 Peripheral nerves, 216 Peritoneum, 135 Petrous bone, 45 Phalanges, 76, 87 Pharynx, 124 Phylogeny, 18 Physiology, 17 Pia mater, 186, 205 Pillar of fauces, 117 Pineal body, 200 Pisces, 19 Pisiform bone, 74 Pituitary body, 191 Plantigrade, 78 Pleura, 172 Plexus, brachial, 220 cardiac, 228 cervical, 219 choroid, 193, 194 lumbar, 223 pulmonary, 228 sacral, 226 solar, 229 Pons Varolii, 188, 195 Portal system, 156 Premaxillary (premaxilla), 51 Preservation of material, 20 Primates, 19 INDEX. Process, acromion, 68 clinoid, 49 coracoid, 68 coronoid, 70 hamular, 51 mammillary, 61 mastoid, 47 odontoid, 60 postorbital, 41 pterygoid, 51 spinous, 57 styloid, 70, 71 transverse, 57 trochanter, 81, 82 Projection fibers, 213 Prostate gland, 183 Proximad, 38 Psychology, 18 Pterygoid bone, 48, 51 Pulmonary arteries, 142 circulation, 143 veins, 159 Q. Quadriceps extensor muscle, 110 R. Radius, 70 Rectum, 128 Reproductive system, 174 Reptilia, 19 Restiform body, 202, 204 Retina, 236 Ribs, 65 Rodentia, 19 Roots of spinal nerves, 206 Rotatoria, 90 Round ligament, 136 S. _ Sacral plexus, 226 | Sacrum, 62 Sagittal, 38 Salivary glands, 131 _ Saphenous nerve, 224 Sarcolemma, 93 Scapholunar, 74 Seapula, 67 | Schneiderian membrane, 239 | Sciatic nerve, 224, 226 notch, 80 | Scrotum, 180 ' Sebaceous glands, 174, INDEX. Secondary motor tract, 215 Semicircular canals, 239 Semilunar ganglion, 230 valves, 142 Sensory tract of brain, 215 Septum lucidum, 196 Serous membrane, 136 Sesamoid bones, 36, 76 Shaft, 39 Shoulder girdle of mammals, 69 Sigmoid cavity, 70 Sinuses, blood, 157 Sirenia, 19 Skeleton, 36 Skin, 32 Solar plexus, 229 Species, 19 Spermatic cord, 181 Sphenoid bone, 48 Sphincter muscle, 194 Spinal cord, 205 preparation for dissection, 26 nerves, 218 Spleen, 165 Stenson’s duct, 132 Sternebra, 63 Sternum, 63 Stomach, 126 of ruminant, 137 Subclasses of mammalia, 19 Subclavian artery, 143 vein, 156 Sublingual gland, 132 Submaxillary gland, 132 Sudoriparous glands, 174 Sulci of brain, 188 Superior pyramidal decussation, 215 Suprarenal bodies (capsules), 167 Sutures, 89 Sympathetic nervous system, 226 Symphysis of mandible, 54 pubis, 80 Synarthroses, 89 Synovia, 90 Synovial membrane, 91 . Syringe, injecting, 21 Systemic circulation, 143 Systems of mammals, 28 lie Tarsalia, 86 Tarsus, 84 Taste-buds, 233 249 Taxonomy, 18 Teeth, 120 of mandible, 54 of maxillary, 52 of premaxillary, 51 Telencephalon, 187 Temporal bone, 44 Tendon, 93 Tentorium, 46 Testes, 180 Thoracic aorta, 143 cavity, 125 duct, 165 nerves, 219 Thymus gland, 125, 166 Thyroid cartilage, 169 gland, 166 Tibia, 83. < Tissues, 29 Toes, 87 Tongue, 119 | Tonsil, 119 Trachea, 170 Tracts of spinal cord, 215 Trapezium, 74 Trapezoid, 74 Tricuspid valve, 141 Tuber cinereum, 191 Tuberosity, 39 Turbinated bones, 53 Tympanum, 237 U. Wina. 10. 74,772 Ulnar nerve, 222 Unciform, 75 Ungulata, 19 digits of, 77 origin of, 71 Unguligrade, 78 Useter, 176: -. Urogenital system of mammals, 184 Urside, 19 Uterus, 177 V. Vagina, 178 Valves, heart, 141 of arteries, 143, 154 of veins, 154 Varieties, 19 Vas deferens, 182 Vascular system, 140 250 INDEX. Vascular system, preparation of, | Vena cava, 156 for dissection, 2 Vein, azygos, 156 brachiocephalic, 156 cephalic, 154 coronary, 156 gastroepiploica, 156 gastrosplenic, 156 hepatic, 154 iliac, 156 iliolumbar, 155 jugular, 157 maxillary, 157 mesenteric, 156 ovarian, 155 pancreatoduodenalis, 156 phrenic, 154 portal, 156 posteava, 154 precava, 154 pulmonary, 159 saphenous, 154 spermatic, 155 sternal, 156 subclavian, 157 suprarenal, 155 vertebral, 156 Veins, structure of, 154 trunk, head, and neck, 155 valves of, 154 Velum interpositum, 193 palati, 117 Venous sinuses, 157 system, 153 Ventricles of brain, 192 Vertebre, 57 caudal, 62 cervical, 58 lumbar, 61 thoracic, 60 Vertebrarterial canal, 59 Vertebrata, 19 | Villi, 130 Viscera, 124 Visual organ, 233 Vital knot, 202 Viviparous, 184 Vocal cords, 169 Vomer, 52 WwW. Wharton’s duct, 132 Willis, circle of, 147 : & Xiphoid process, 63 Z. Zygoma, 44, 54 Zygomatic gland, 132 process, 44 MEDICAL BOOKS Note Subject Index, Page 6 There have been sold more than 145,000 copies of Gould’s Dictionaries See Pages 12 and 13 P. BLAKISTON’S SON & COMPANY PUBLISHERS OF MEDICAL AND SCIENTIFIC BOOKS i012 WALNUT STREET, PHILADELPHIA Montgomery’s Gynecology New Edition—Just Ready A modern comprehensive Text-Book. By EpwaArp E. MONTGOMERY, M.D., Professor of Gynecology in Jefferson Medical College, Philadelphia; Gynecologist to the Jefferson and St. Joseph’s Hospitals, etc. Second Edition, Revised and Enlarged. 570 Illustrations, many of which are from original sources. Octavo. Cloth, $5.00; Leather, $6.00 *,* This is a systematic modern treatise on Diseases of Women. The author’s aim has been to produce a book that will be thorough and practical in every particular. The illustrations, nearly all of which are from original sources, have for the most part been drawn by special artists who, for a number of months, devoted their sole attention to this work. The present edition has been thoroughly revised. ‘* The book is one that can be recommended to the student, to the general practitioner—who must sometimes be a gynecologist to a certain extent whether he will or not—and to the specialist, as an ideal and in every way complete work on the gynecology of to-day—a practical work for practical workers.’’—T7he /Jour- nal of the American Medical Association. Byford’s Gynecology Third Revised Edition A MANVAL FOR STUDENTS AND PHYSICIANS By Henry T. ByForD, M.D., Professor of Gynecology and Clinical Gynecology in the College of Physicians and Sur- geons of Chicago; Professor of Clinical Gynecology, Women’s Medical School of Northwestern University, and in Post-Graduate Medical School, etc. Third Edition, En- larged. 363 Illustrations, many of which are from original drawings and several of which are Colored. 12mo. Cloth, $3.00 ‘* As a book to help the student to quickly review what ought to be gotten up, so as to be prepared for the early examination, it is of great service. Sucha book would also make a most excellent text- book for the college class room.’’— Virginia Medical Semi-Monthly, Richmond. By JAMES TYSON, M.D.. Professor of Medicine, University of Pennsylvania, Physician to the Philadelphia Hospital, etc. The Practice of Medicine. Third Edition. A Text-Book for Physicians and Students, with Special Ref- erence to Diagnosis and Treatment. With Colored Plates and many other Illustrations. Third Edition, Revised and Enlarged. 124 Illustrations. 8vo. Cloth, $5.50; Leather, $6.50; Half Russia, $7.50 *,* This edition has been entirely reset from new type. The author has revised it carefully and thoroughly, and added much new material and new illustrations. “We are firmly convinced that at the present time Dr. Tyson’s book on Practice can be most heartily commended to both the practi- tioner and student as a sate, reliable, and thuroughly up-to-date guide in the practice of medicine.”’— The Therapeutic Gazette. ** The clinical descriptions are clear and full, and the methods of treatment described are those generally recognized as being the most modern and satisfactory.”’— The London Lencet. Guide to the Examination of Urine. Tenth Edition. For the Use of Physicians and Students. With Colored Plate and Numerous Illustrations Engraved on Wood. Tenth Edition, Revised, Enlarged, and in many parts entirely rewritten. . Cloth, $1.50 ** A French translation of this book has been pub- lished in Parts. ‘“ The book is probably more widely and generally known and ap- preciated than any of its similars in subject and scope.’’—New York Medical Journal. “‘ The book is a reliable one, and should find a place in the library of every practitioner and student of medicine.’’—Bostox Medical and Surgical Journal. Handbook of Physical Diagnosis. Fourth Edition. Revised and Enlarged. With two Colored Plates and 55 other Illustrations. 298 pages. I2mo. Cloth, $1.50 ‘< Like everything else emanating from this distinguished author this little book is replete with practical information from beginning to end.’’—The Chicago Medical Recorder. “The author approaches his subject from a practical point of view and the little work will prove a good friend to the student.’’— The American Journal of the Medical Sciences. 3 . NEW THIRD EDITION—NOW READY Morris’ ANATOMY Rewritten—Revised—Improved WITH MANY NEW ILLUSTRATIONS Out of 102 of the leading medical schools 60 recommend “Morris.” It contains many features of special advantage to students. It is modern, up-to-date in every respect. It has been carefully revised, the articles on Osteology and Nervous System having been rewritten. Each copy con- tains the colored illustrations anda Thumb Index. Octavo. With 846 Illustrations, of which 267 are printed in colors. CLOTH, $6.00; LEATHER, $7.00 *« The ever-growing popularity of the book with teachers and stu- dents is an index of its value, and it may safely be recommended to all interested.”’—From The Medical Record, New York. “« Of all the text-books of moderate size on human anatomy in the English language, Morris is undoubtedly the most up-to-date and accu- rate.”’—From 7ke Philadelphia Medical Journal. McMurrich—Embryology THE DEVELOPMENT OF THE HUMAN BODY With 270 Illustrations A Text-Book for Medical Students. By J. PLAYFAIR McMourricu, Professor of Anatomy, Medical Department, University of Michigan. 527 pages. Cloth, $3.00 = NINTH EDITION POTTER’S MATERIA MEDICA, PHARMACY, ann THERAPEUTICS An Exhaustive Handbook Including the Action of Medicines, Special Therapeutics of Disease, Official and Practical Pharmacy, and Minute Direc- tions for Prescription Writing, etc. Including over 650 Prescriptions and Formule. By SAMUEL O. L. PoTTER, M.A., M.D., M.R.C.P. (Lond.), formerly Professor of the Principles and Practice of Medicine, Cooper Medical Col- lege, San Francisco; Major and Brigade Surgeon, U. S. Vol. Ninth Edition, Revised and Enlarged. 8vo. With Thumb Index in each copy. Cloth, $5.00; Leather, $6.00 *,* This is the most complete and trustworthy book for the use of students and physicians. Students who pur- chase it will find it to contain a vast deal of information not in the usual text-books arranged in the most practical man- ner for facilitating study and reference. It cannot be sur- passed as a physician’s working book. WHITE AND WILCOX. Materia Medica, Pharmacy, Pharmacology, and Thera- peutics. Fifth Edition. A Handbook for Students. By W. HALE WHITE, M.D., F.R.C.P., etc., Physician to, and Lecturer on Materia Medica and Therapeutics at, Guy’s Hospital, etc. Fifth American Edition, Revised by REYNOLD W. WILCcox, M A, M.D.,LL.D., Professor of Clinical Medicine and Thera- peutics at the New York Post-Graduate Medical School and Hospital; Visiting Physician, St. Mark’s Hospital; Assist- ant Visiting Physician, Bellevue Hospital. 12mo. Cloth, $3.00 ; Leather, $3.50 5 SUBJECT INDEX. Gould’s Medical Dictionaries, L Morris’ Anatomy, New Edition, = = Compends for Students, = SUBJECT. Alimentary Canal (see Sur- Fery). 5.2.3 eee eee 24 Anatomy 23555 75s ee ese Anesthetics «. 235.442. 8, 19 Autopsies (see poe ey 20 Bacteriology 8 Bandaging (see Surgery).. 24 Blood, Examination of... 8 Braintekc . ees ee 8 Chemistry. Physies-.... 9 Children, Diseases of..... 11 Chimatology- 23. .5..-2 22.5 19 Clinical Charts.......... 25 Compeéends) 233 Sori: oe 21 Consumption (see Pune). ee | Cyclopedia of Medicine. Ae Dentisiry i262 <-hececkes Diabetes (see Urin. Organs) Ds DiaAgnGsisss cece ae tee 11 Diagrams (see Anatomy). 8 Dictionaries, Cyclopedias. 12 Dist. andi Pood: 35 -.o2.% 13 Disinfection \-< 25,.<22012 <5 16 Drsscetors: 2. toe ees eee 7 Har vet ee ee kee 14 Heemetiy -f<. eacecos 14 Bimbryolery, 3.2 ose. 25 ff Emergencies ..........-- 24 Bye sei eae eee 14 Heyes = cops eae cee 15 MOO 5. ook os aoe ee Se 13 Formulanés’ = oe ~ 22... 7 Gynecolory 5th Edition. New Lilustrations. .00 FULLERTON. Surgical Nursing. 3d Ed. 69 Illus. $1.00 HAMILTON. Lectures on Tumors. 3d Edition. $1.25 HEATH. Minor Surgery and Bandaging. 12th Edition, Re- vised and Enlarged. 195 Lllus., Formule, Diet List, ete. $1.50 HEATH. Clinical Lectures on Surgical Subjects. Second Beries. yen HORWITZ. Compend of Surgery and Bandaging. Including Minor Surgery, Amputations, Fractures, Dislocations, Surgical Diseases, etc., with Differential Diagnosis and Treatment. 5th Edition, very much Enlarged and Rearranged. 167 Illus., 98 Formule. Cloth, .80; Interleaved, $1.00 JACOBSON. Operations of Surgery. 4th Ed., Enlarged. 550 Illus. Two volumes. Cloth, $10.00; Leather, $12.00 KEAY. Medical Treatment of Gall-Stones. $1.25 KEHR. Gall-stone Disease. Translated by WILLIAM WOTKYNS SEYMOUR, M.D. $2.50 S. Surgical Experiences in South Africa. 1899-1900. Illustrated. $4.00 MAYLARD. Surgery of the Alimentary Canal. 97 Illustrations. 2d Edition, Revised. $3.00 MEDICAL BOOKS. 25 MOULLIN. Text-Book of Surgery. With Special Reference to Treatment. 3d American Edition. Revised and edited by Joun B. HAMILTON, M.D., LL-D., Professor of the Principles of Surgery and Clinical Surgery, Rush Medical College, Chicago. 623 Illustrations, many of which are printed in colors. Cloth, $6.00; Leather, $7.00 SMITH. Abdominal Surgery. Being a Systematic Description of all the Principal Operations. 224 Illustrations. 6th Edi- tion. 2 volumes. Cloth, $10.00 VOSWINKEL. Surgical Nursing. Second Edition, Revised and Enlarged. 111 Illustrations. $1.00 WALSHAM. Manual of Practical Surgery. 7th Ed., Revised and Enlarged. 483 Engravings. 950 pages. $3.50 TEMPERATURE CHARTS, ETC. GRIFFITH. Graphic Clinical Chart for Recording Tempera- ture, Respiration, Pulse, Day of Disease, Date, Age, Sex, Occu- pation, Name, etc. Printed in three colors. Sample copies free. Put up in loose packages of fifty, 50 cts. Price to Hospitals, 500 copies, $4.00; 1000 copies, $7.50. KEEN’S Clinical Charts. Seven Outline Drawings of the Body, on which may be marked the Course of Disease, Fractures, Operations, etc. Each Drawing may be had separately, twenty-five to pad, 25 cents. THROAT AND NOSE (see also Ear). COHEN. The Throat and Voice. Illustrated. -40 HALL. Diseases of the Nose and Throat. 2d Edition, Enlarged. Two Colored Plates and 80 Illustrations. $2.75 HOLLOPETER. Hay Fever. Its Successful Treatment. $1.00 KNIGHT. Diseases of the Throat. A Manual for Students. Illustrated. Nearly Ready. KYLE (J. J.). Diseases of the Ear, Nose, and Throat. A Com- pend for Students. Illustrated. .80; Interleaved, $1.00 McBRIDE. Diseases of the Throat, Nose, and Ear. With Col- ored Illustrations from Original Drawings. 3d Ed. $7.00 POTTER. Speech and its Defects. Considered Physiologically, Pathologically, and Remedially. $1.00 URINE AND URINARY ORGANS. ACTON. The Functions and Disorders of the Reproductive Organs in Childhood, Youth, Adult Age, and Advanced Life, Considered in their Physiological, Social, and Moral Relations. 8th Edition. $1.75 CASPER AND RICHTER. Functional Kidney Diagnosis. $1.50 HOLLAND. The Urine, the Gastric Contents, the Common Poisons, and the Milk. Memoranda, Chemical and Micro- scopical, for Laboratory Use. Illustrated and Interleaved. 6th Edition. ' $1.00 KLEEN. Diabetes and Glycosuria. $2.50 26 SUBJECT CATALOGUE. MEMMINGER. Diagnosis by the Urine. 2d Edition. 24 Illus- trations. $1.00 MORRIS. Renal Surgery, with Special Reference to Stone in the Kidney and Ureter and to the Surgical Treatment of Caleulous Anuria. Illustrated. $2.00 MOULLIN. Enlargement of the Prostate. Its Treatment and Radical Cure. 2d Edition. Illustrated. $1.75 MOULLIN. Inflammation of the Bladder and Urinary Fever. Octavo. $1.50 SCOTT. The Urine. Its Clinical and Microscopical Examina- tion. 41 Lithographic Plates and other Illustrations. Quarto. Cloth, $5.00 TYSON. Guide to Examination of the Urine. For the Use of Physicians and Students. With Colored Plate and Numerous Illustrations engraved on wood. 10th Edition, Revised, En- larged, and partly Rewritten. With New Illustrations. Just Ready. $1.50 VAN NUYS. Chemical Analysis of Urine. 39 Illus. $1.00 VENEREAL DISEASES. GOWERS. Syphilis and the Nervous System. $1.00 STURGIS AND CABOT. Student’s Manual of Venereal Diseases. 7th Revised and Enlarged Edition. 12mo. $1.25 VETERINARY. BALLOU. Equine Anatomy and Physiology. 29 Graphic Illustrations. .80; Interleaved, $1.00 JACOBSON. The Operations of Surgery. By W. H. A. Jacosson, F.R.c.8., Surgeon to Guy’s Hospital; Consulting Surgeon Royal Hospital for Children and Women; and F. J. STEWARD, F.R.c.s., Assistant Surgeon Guy’s Hospital. Fourth Edition—Revised, Enlarged, and Improved. 550 Illustrations. Two Volumes, Octavo, 1524 pages. Cloth, $10.00; Sheep, $12.00 “The important anatomical points are clearly set forth, the conditions indicating or contraindicating operative interference are given, the details of the operations themselves are brought forward prominently, and frequently the after-treatment is considered. Herein is one of the strong points of the book.”— New York Medical Journal. aie know of no series of books issued by any house that so a meets our Save! as these ? Quiz-Compends?. They are arranged, full and concise, and are really the best line of text-books that could be found for either student or practitioner.” —Southern Clinic. BLAKISTON’S ?QUIZ-COMPENDS P The Best Series of Manuals for the Use of Students. Price of each, Cloth, .80. Interleaved, for taking Notes, $1.00 These Compends are based on the most popular text-books and the lectures of prominent professors, and are kept constantly revised, so that they may thoroughly represent the present state of the subjects upon which they treat. The authors have had = e experience as Quiz-Masters and attaches of colleges, and are acquainted with the wants of students. They are arranged a the most approved form, thorough and concise, containing nearly 1000 illustrations and lithograph plates, inserted wherever they could be used to advantage. Can be used by students of any college. They contain information nowhere else collected in such a condensed, practical shape. No. 1. POTTER. HUMAN ANATOMY. Seventh Edition. 138 : Illustrations and 16 Plates of Nerves and Arteries. No. 2. HUGHES. PRACTICE OF MEDICINE. Part I. Sixth Edition, Enlarged and Improved. No. 3. HUGHES. PRACTICE OF MEDICINE. Part II. Sixth Edition, Revised and Improved. No. 4. BRUBAKER. PHYSIOLOGY. Eleventh Edition. Illus. No. 5. LANDIS. OBSTETRICS. Seventh Edition. 52 Illus. No. 6. POTTER. MATERIA MEDICA, THERAPEUTICS, AND PRESCRIPTION WRITING. Sixth Revised Edition. No. 7. WELLS. GYNECOLOGY. Third Edition. 140 Illus. No. 8. GOULD AND PYLE. DISEASES OF THE EYE. Second Edition. Refraction, Treatment, Surgery, etc. 109 Illus. No. 9. HORWITZ. SURGERY. Including Minor Surgery, Bandaging, Surgical Diseases, Differential Diagnosis and Treatment. Fifth Edition. With 98 Formule and 71 Illus- trations. No. 10. LEFFMANN. MEDICAL CHEMISTRY. Fourth Edi- tion. Including Urinalysis, Animal Chemistry, Chemistry of Milk, Blood, Tissues, the Secretions, etc. No. 11. STEWART. PHARMACY. Fifth Edition. Based upon Prof. Remington’s Text-Book of Pharmacy. No. 12. BALLOU. EQUINE ANATOMY AND PHYSIOLOGY. 29 graphic Illustrations. ‘ No. 13. WARREN. DENTAL PATHOLOGY AND DENTAL MEDICINE. Third Edition, Illustrated. No. 14. HATFIELD. DISEASES OF CHILDREN. 3d Edition. No. 15. THAYER. GENERAL PATHOLOGY. 78 Illus. No. 16. SCHAMBERG. DISEASES OF THE SKIN. Third Edition, Revised and Enlarged. 106 Illustrations. No. 17. CUSHING. HISTOLOGY. Illustrated. In Press. No. 18. THAYER. SPECIAL PATHOLOGY. 34 Illustrations. No. 19. KYLE. DISEASES OF THE EAR, NOSE, AND THROAT. Illustrated. 27 DA COSTA Clinical Hematology A Practical Guide to the Examination of the Blood by Clinical Methods. With Reference to the Diagnosis of Disease. With Colored Illustrations. Cloth, $5.00 *.* A new, thorough, systematic, and comprehensive work, its purpose being, first, to show how to examine the blood, and second, how to diagnose from such examination diseases of the blood itself and general diseases. The author’s aim has been to cover not alone the field of original research, but to supply a book for the student, the hospital physician and the general practitioner. It will be found wanting in none of these respects. OERTEL Medical Microscopy JUST READY A GUIDE TO DIAGNOSIS, ELEMEN- TARY LABORATORY METHODS, AND MICROSCOPIC TECHNIC By“? BS Oriree,” Wie Professor of Pathology and Clinical Microscopy, Medical Depart- ment, University of Georgia. WITH 131 ILLUSTRATIONS. 12mo. Cloth, $2.00 28 The Pocket Cyclopedia of Medicine and Surgery Full Limp Leather, Round Corners, Gill Edges, $1.00 With Thumb Index, $1.25 Uniform with ** Gould’s Pocket Dictionary ’” A concise practical volume of nearly 600 pages, containing a vast amount of infor- mation on all medical subjects, including Diagnosis and ‘Treatment of Disease, with Formulas and Prescriptions, Emer- gencies, Poisons, Drugs and Their Uses, Nutsing, Surgical Procedures, Dose List in both English and Metric Systems, etc. By Drs. Gould and Pyle Based upon their large “ Cyclopedia of Medicine and Surgery.” 2 % &% *,* This is a new book which will prove of the greatest value to students. It is to the broad field of general medi- cal information what ‘‘Gould’s Pocket Dictionary’’ is to the more special one of definition and pronunciation of words. The articles are concise but thorough, and arranged in shape for quick reference. In no other book can be found so much exact detailed knowledge so conveniently classified, so evenly distributed, so methodically grouped. It is Multum in Parvo. Sample Pages Free. 29 A NEW EDITION — CROCKER ON THE SKIN The Diseases of the Skin. Their Description, Pathology, Diagnosis, and Treatment, with Special Reference to the Skin Eruptions of Children. By H. RADCLIFFE CROCKER, M.D., Physician to the Department of Skin Diseases, Uni- versity College Hospital, London. With new Illustrations. Third Edition, Rewritten and Enlarged OCTAVO. JUST READY; CLOTH, $5.00 *,* This new edition will easily hold the high position given the previous printings. The author is a member of American, English, French, German, and Italian Dermato- logical Societies, and a recognized authority the world over. STURGIS—MANUAL OF VENEREAL DISEASES By F. R. STURGIS, M.D., Sometime Clinical Professor of Venereal Diseases in the Medical Department of the Uni- versity of the City of New York. Seventh Edition, Revised and in Part Rewritten by the Author and FoLLEN CABzoT, M.D., Instructor in Genito-Urinary and Venereal Diseases in the Cornell University Medical College. I2mo. 216 pages. Cloth, $1.25 */* This manual was originally written for students’ use, and is as concise and as practical as possible. It pre- sents a careful, condensed description of the commoner forms of venereal diseases which occur in the practice of the general physician, together with the most approved remedies. 30 FOR THE DISSECTING ROOM Holden’s Anatomy—Seventh Edition 320 Illustrations A Manual of the Dissections of the Human Body. By JOHN LANGTON, F.R.C.S. Carefully Revised by A. HEWSON, M.D., Demonstrator of Anatomy, Jefferson Medical College, Phila- delphia, etc. 320 Illustrations. Two small compact vol- umes. I2mo. Vol. I. Scalp, Face, Orbit, Neck, Throat, Thorax, Upper Extremity. 435 pages. 153 Illustrations. Oil Cloth, $1.50 Vol. II. Abdomen, Perineum, Lower Extremity, Brain, Eye, Ear, Mammary Gland, Scrotum, Testes. 445 pages. 167 Illustrations. Oil Cloth, $1.50 Each volume sold separately, Hughes and Keith — Dissections Illustrated A Manual of Dissections by ALFRED W. HUGHES, M.B., M.R.C.S. (Edin.), late Professor of Anatomy and Dean of Medical Faculty, King’s College, London, etc., and ARTHUR KEITH, M.D., Joint Lecturer on Anatomy, London Hospital Medical College, etc. In three parts. With 527 Colored and other Illustrations. I. Upper and Lower Extremity. 38 Plates, 116 other Illustrations. Cloth, $3.co II. Abdomen. Thorax. 4 Plates, 149 other Illus- trations. Cloth, $3.00 III. Head, Neck, and Central Nervous System. 16 Plates, 204 other Illustrations. Cloth, $3.00 Each volume sold separately. *,* The student will find it of great advantage to have a ‘* Dissector’’ to supplement his regular text-book on anatomy. These books meet all requirements, and as they can be purchased in parts as wanted, the outlay is small. 31 EDGAR’S OBSTETRICS A NEW TEXT - BOOK 1221 Illustrations Edgar’s Obstetrics excels all other works on this subject in completeness, in uni- formity and consistency in arrangement, thoroughness and clearness in handling details, and in the number > and usefulness of its illus- trations. OCTAVO. CLOTH, $6.00; SHEEP, $7.00 MOP A Prtave fee © ste Pelidese tetigh Luis sed baal cl ok ee 9 OWE © Ofer t rowmE bre ate we gee ~ Labbe tlh biti bao er "s 2 ~rowooret we ‘bse + tert 1 eee YF = orgies ee #0040 96 G07 RP NE Be © ae ye eats aed oe at ee ee aoe v ae wee ew ets real el od ee ee ve W1@Or 8 os ne ~ Le ea Wye e Weer ert 8 op ere both es Co 6 ° 2h he - oe Oar Oe Oe VE rt Ow boc. 5 pee =e Powe re ay er 2 8 8 eR 9m +N E weie WO" we a 5 dg Came To) a ee ee eee ey He wos eg . sae 4 . ee ied ) Pe we g grate ey une ie wah, Bem Os 6 4 ts 6. ©4100). no Je dinars mm we. 0 € 8 et Ale Rt el tlie IE) ore , ‘ . ’ - ee . o8 CS 00'S Sues sine, OF 6. @ § 4 0's © 6 . vine the ke bo 4 6 18 Om ae 68 om wie eees es, . téa:ou , © oni , of «ple ofS ORV OPTS WONG! 400. were sm « ewes iy! © # ehbde a er ot oo Gee 8 6 &e 66 251 . es 4 ate? iO OO Sie Var dwie . * os ooo % POC HWE e © eaten $4 e's @ 8 ; we ee #s . iid ee a ee Veeret tees e* ve thie totelg ‘ + Valet +e & BO 9 whee ete Le he ow’ . . ee a ‘ - ‘ sees Ch ee see ° ’ viteete « ou § ess * winlsrers ov" biwlvi et Gs thes, s,',".", .f.', dean 9% c+m . SP > bee's a CEP WCC OR Ieee hg sss 5 14 Pot’ ° * wide vo« 10 Oe ee re wee 9 MN) 9 6! n i* ele as ' yore . ‘ bette LDieed weet t pars ets: Stet: . -+-e NO 6 'ee0' Oo Pulte. Gee 6 ire st , * . elt ee Oe ws idee are. up oo 0 ere 5 on eee ene * +h * womens * © Se eheterGeies ¢ 1 6 , ite oe ie tee ee » stots Oe ee wete e808 te hie cee | 1% tu@ + ee tae th Vir Mate Loa 4 TT ae mer ie br) cle) « els © the 4fF @ eres oe 28 ere weet Oe > home's ee, ha oo oe} et 2*0— Eoerars bo « 4 oe As 4% tomlp ie oes oe 8IP Wes elms ° Tt. 0." Go sinw 6+ ei¢ s | RPL Ge e* <4” . oor 5 et Pe ee eh 4 et a 4 er ‘ (eee ‘ . swiebee a v= 6 P i «4 se ' ’ 4 ‘ oe ' ed » io es ‘ er ‘Virier ss. o “e as. § ’ re) aw, * . _ ‘oe ‘ ' ;ea ts jos ire sew ia OMS a s'dis weld om Teo aig, oe ‘+ . er ay a to ee ee ee ee a on ln ed ee lf ee ae v ©) &eo ‘ FFP Oe Oe ret 94 +¢8 5-5 ‘4 PPT Ce bbgevek ease s . by = pass ee Pel ted ud at died Lads A ee ee . oy 4) tee ee aede tS ONO MOTO 4 bs bie tb P ee oe ee « P 7 . ‘ ' oss ‘ 7. fee . : edied t * rene ‘ vs alt deol . « ee e< A ed Pry? — eS +e 77° oe cee * id ~~ o ; re - : é- ian ; a ‘ p pow ‘ Py" ~4 ‘~~ +? “y - . 4 . - 7 pes ia ’ ‘ + te “we ah, - by ~ . . : 7 ~~ “ mit « +* i is “ ss . ‘os A + i aed , : ¢ i + “* - “+46 7 + AeA a , be od ° ’ owe . awe . Ai F Fit os . . . ese ‘ ’ - Fue 3 ‘ aner ere » . ._ | . « : : bed * - Ps ° * . . ' ° 7% ‘4 . - 7 ’ : i) * or ‘ 2 rere - . * o/- . ' +m : ’ P + . - . res ‘ ‘ —— a ‘ : F ‘ ~ e cl ’ y ‘ “65> 5 : ~ oe ha an . ‘ wi per pe . ~ os of hd - M4 A i . ‘ ‘ < > on . : x : um’, hs