BJOLOGY LIBRAKY HAND-BOOK HUMAN'ANATOIY AND PHYSIOLOGY.' USE OF STUDENTS. BY HENRY HARTSHORNE, A.M., M.D., PROFESSOR OF ORGANIC SCIENCE AND PHILOSOPHY IN HAVERFORD COLLEGE J PROFESSOR OF HYGIENE IN THE UNIVERSITY OF PENNSYLVANIA, AUXILIARY FACULTY OF MEDICINE ; PROFESSOR OF PHYSIOLOGY AND HYGIENE IN PENNSYLVANIA COLLEGE OF DENTAL SURGERY ; ETC. ETC. . WITH ONE HUNDRED AND SIXTY-SIX ILLUSTRATIONS. PHILADELPHIA: HENET C. LEA. 1869. V .*c. ^ Entered according to Act of Congress, in the year 1869, by HENRY C. LEA, in the Clerk's Office of the District Court of the United States in and for the Eastern District of Pennsylvania, PHILADELPHIA : COLLINS, PRINTER, 705 JAYNE STREET. PREFACE. THE purpose of the* author of this Hand-Book has been to present in the briefest manner all that is most essential in Human Anatomy, and all that is most positive and im- portant in Physiology, for the especial use of the student during his attendance upon lectures. Although designed for medical students, it is believed that it will not be too technical for others ; particularly if its use be combined with oral instruction and demonstration. The illustra- tions have been selected with much care from standard authorities. LIST OF ILLUSTRATIONS. ANATOMY. FIG. PAGE 1. Human Skeleton .... 24 2. Transverse Section of an Old Tibia 25 3. Lateral View of the Spinal Column 26 4. The Atlas ..... 27 5. A Dorsal Vertebra .... 27 6. View of a Lumbar Vertebra . . 28 7. Left Temporal Bone ... 30 8. Anterior and Inferior Surface of the Sphenoid Bone ... 32 9. Upper and Posterior View of the Ethmoid Bone . . . .33 10. Superior Maxilla . . ... 35 11. The Nasal Cavities ... 36 12. The Palate Bone . . ~ . .36 13. Left Nasal Fossa . . . .37 14. Front View of the Skull . . 39 15. External View of the Base of the Cranium 40 16. Internal Surface of the Base of the Cranium 41 17. Front View of the Thorax . . 42 18. Anterior View of the Male Pelvis 44 19. Venter of Scapula .... 46 20. Anterior View of Humerus of the Right Side 47 21. Anterior View of Radius of Right Side . . ... . .48 22. Anterior View of Ulna of the Left side . . \. ' > . . 49 23. Articulation of Bones of the Carpus 50 24. Posterior View of the Femur . 51 25. Anterior View of the Tibia . . 52 26. The Fibula 53 27. Upper Surface of the Left Foot . 54 28. Eight Teeth of One Side of the Upper Jaw 56 29. Eight Teeth of One Side of Lower Jaw ... 56 FIG. PAGE 30. Magnified Section of a Tooth . 57 31 . Teeth at Five Years ... 58 32. Ligaments of Acromio-Clavicular and Scapulo-Humeral Articula- tions 62 33. Internal View of the Elbow- Joint 63 34. Ligaments of the Hip-Joint and Pelvis 64 35. The Knee-Joint laid open . . 65 36. Vertical Section of the Ankle-Join t and Foot 67 37. Upper Surface of the Tongue . . 69 38. Salivary Glands .... 70 39. Parietes of the Abdomen . . 73 40. The Peritoneum .... 74 41. Organs of Digestion . ... 76 '42. Viscera, after removal of the Fat in the Chest and the Omentum Maj us of the Abdomen . . 78 43. The Large Intestine ... 80 44. The Larynx . . . .83 45. View of the Larynx from Above . 85 46. Bronchi and Bloodvessels . . 88 47. Minute Structure of the Testis . 95 48. Uterus and its Appendages . . 98 49. Viscera of Female Pelvis . . 100 50. Section of Mammary Gland . . 101 51. The Left Ventricle . . . .102 52. Interior of the Right Ventricle . 103 53. Arteries of the Arm and Shoulder 111 54. One of the Anomalies of the Bra- chial Artery 112 55. Arteries of the Pelvis and Thigh . 118 56. Anterior Tibial Artery . . .119 57. Superficial Bones of the Upper Ex- tremity 123 58. Superficial Veins of the Legs . . 126 VI LIST OF ILLUSTRATIONS. FIN. PAGE 59. Lymphatics of the Jejunum and Mesentery, injected ; the Arteries are also injected .... 128 60. Femoral Iliac and Aortic Lympha- tic Vessels and Glands . . 129 61. Sebaceous Glands and Follicles of Hairs in the Skin of the Axilla . 131 62. Sudoriferous Organs of the Sole of the Foot ..... 132 63. Muscles front view . . .135 64. Muscles back view . . . 141 65. Superior Muscles of the Upper Front of the trunk . . .143 66. Lateral View of the Muscles of the Trunk 67. Abdominal Muscles and Inguinal Canal ..... y 6S. Second Layer of Muscles of the Back ...... 69. Outer Layer of Muscles on the Front of the Forearm . . . 70. Outer Layer of Muscles on the Back of the Forearm . . . 146 117 140 152 154 71. Deep-Seated Muscles on the Poste- rior Part of the Hip-Joint . . 157 FIG. PAGE 72. Muscles of the Back of the Thigh . 159 73. Muscles of the Front of the Leg . 160 74. Anterior View of the Brain and Spinal Marrow . . . .162 75. Base of the Cerebrum and Cerebel- lum 165 76. Longitudinal Section of the Brain 166 77. Lateral Ventricles of the Cerebrum 167 78. The Second Pair, or Optic Nerves 173 79 Distribution of the Fifth Pair . 174 80. The Nerves 181 81. The Brachial Plexus . . . 1S2 82. Nerves of the Front of the Fore- arm 184 83. Posterior Tibial Nerve . . .189 84. Anterior Tibial Nerve . . .190 85. Thoracic Ganglia . . . .194 86. Section of the Eye . . . .196 87. Transverse Section of the Eye . 198 88. Crystalline lens divided . . 198 89. Muscles of the Eyeball . . .198 90. Lachrymal Canals . . . .199 91. Ossicles of the Ear . . . .200 92. View of the Ear .... 201 93. Arteries of the Perineum . 204 PHYSIOLOGY. 94. Blood Corpuscles . 95. Blood Coagula 96. Blood Coagula 97. Blood Crystals 98. Nucleated Cells 99. Multiplication o 100. Pavement Epith 101. Ciliated Epithelium 102. White Fibrous Tisst 103. Yellow Fibrous Tisi 104. Fibrous Cartilage . 105. Osseous Tissue 106. Fat Vesicles 107. Striped Muscle 108. Smooth Muscle 109. Nerve Cells 110. Nerve Filaments 111. Hand of Man 112. Deglutition 113. The Stomach 114. Mucous Mem magnified sles .... 218 116. Follicles of Pig's Stomach . . 236 219 117. Villi of Intestine . . 2.37 219 118. Piece of Ileum . 237 1. ' 219 11Q ThvmiiR 38 Is .... 222 120. The Lymphatics . . 239 of Cells . 223 121. Diagram of the Circulation . . 241 thelium . 225 122. Semilunar Valves . . 242 elium 225 123. Veins of the Base of the Heart . 243 Tissue . 227 124. Capillaries .... . 245 is Tissue . 227 125. Capillaries of a Tooth . . 245 age . 227 | 126. Diagram of Air-Cells . . 247 e 228 127. Brunner's Gland, magnified . . 252 228 128. Lobule of Liver . 253 3 .... 229 129. Lobule of Liver . 254 e 229 130. Section of Liver of the Horse . 255 . 230 131. Bile-duct and Cells . 256 QtS . 230 132. Section of Kidney . . 257 ind of Orang . 232 133. Structure of Kidney . 258 . 234 134. Section of Skin . !!.-: 235 13.i. Unfertilized Ovum . . 261 ra ne of the Stomach, 136. Graafian Vesicle and Ovum . . 262 263 Section of the same 23.) 138. The Biceps Muscle . . 266 LIST OP ILLUSTRATIONS. vii FTO. PAGE 139. Diagram of a Ganglion . . .268 140. Ganglion-cells . . . .271 141. Junction of Spinal and Sympa- thetic Systems 272 142. Section of Spinal Cord . . .273 143. Diagram of Encephalon . . . 275 144. Medulla Oblongata . . .276 145. Cerebellum 277 146. Longitudinal Section of the Brain . 278 147. Chiasm of Optic Nerves . . 280 148. Papilla of Palm . . . .285 149. Pacinian Corpuscles . . .285 150. Pacinian Corpuscle . . .285 151. Fungiform Papillae of Tongue . 286 152. The Nasal Cavity . . . .287 153. The Ear . . 288 FIO. FADE 154. Ossicles of the Ear . . . . 289 155. Labyrinth of the Ear . . .289 156. The Cochlea 290 157. Section of Eyeball . . . .293 158. Stereoscopic Vision . . .297 159. Glottis, from above . . .299 160. The Larynx opened . . .300 161. The Amnion and Chorion . . 303 162. Diagram representing a Human Ovum in the Second Month . . 303 163. Diagram of the Foetus and Mem- branes about the Sixth Week . 305 164. The Foetal Circulation . . .308 165. Foetal Skeleton . . . .310 166. Development of Teeth . . .311 A MANUAL OF ANATOMY CONTENTS. PAGE DEFINITIONS 23 CHAPTER I. BONES. OSSEOUS TISSUE .......... 23 Composition .......... 23 Structure ........... 24 Number of the bones 2(5 SPINE ............ 26 Cervical Vertebrae 27 Dorsal Vertebrae 27 Lumbar Vertebrae 28 Sacrum ........... 28 Os Coccygis 28 HEAD 28 Cranium 28 Frontal Bone 29 Parietal Bones 29 Occiput 29 Temporal Bones . .30 Sphenoid Bone 31 Ethmoid Bone 33 Bones of the Face . . . . . . . . . 34 Malar Bones 34 Superior Maxillary Bones .34 Nasal Bones ......... 35 Lachrymal Bones . . . . . . . .36 Palate Bones 36 Vomer . .37 Inferior Turbinated Bones 37 Inferior Maxillary Boiie ....... 38 16 CONTENTS. PAGE General Remarks on the Head 38 Sutures, 38 Diploe, 38 Exterior Regions, 39 Interior Regions of the Cranium, 39 Orbit, 39 Nasal Cavi- ties, 39 Ossa Triquetra, 40 Fontauels, 40 Diame- ters, 40 Capacity and Form, 41 Facial Angle, 41. Hyoid Bone 42 THORAX . 42 Sternum 42 Ribs 43 PELVIS 43 Ossa Innominata ......... 43 Ilium 43 Pubes ' . .45 Ischium .......... 45 Acetabulum % . 45 Thyroid Foramen ........ 45 UPPER EXTREMITY 46 Shoulder 46 Scapula 46 Clavicle 47 Arm 47 Humerus .......... 47 Forearm ........... 48 Radius . . 48 Ulna 49 Carpus 49 Metacarpal Bones ......... 50 Fingers ........... 50 LOWER EXTREMITY .......... 51 Femur .......... 51 Patella 52 Tibia 52 Fibula 53 Tarsus 53 Metatarsal Bones 55 Toes 55 TEETH 56 Structure 57 Development 57 CONTENTS. 17 CHAPTER II. ARTICULATIONS. PAGE Vertebral Articulations 60 Occiput and Atlas 60 Atlas and Axis 60 Pelvic Ligaments 60 Temporo-maxillary Articulations ....... 61 Thoracic Articulations 61 The Shoulder 62 The Elbow 62 The Wrist . . ' .03 Articulations of the Hand 64 Hip-joint 65 Knee-joint ....... .... 65 Tibio-fibular Articulations 66 Ankle-joint 66 "Tarsal Articulations 66 Metatarsal and Phalangeal Articulations . . . . . .67 CHAPTER III. DIGESTIVE ORGANS. Mouth . 68 Tongue 68 Salivary Glands 69 Palate 70 Pharynx 71 (Esophagus 72 Abdomen . . . . . . . . . .72 Peritoneum ........... 74 Stomach . . . ' .75 Intestines ........... 77 Duodenum 77 Jejunum 77 Ileum 77 Mucous Membrane of Small Intestine ...... 77 Large Intestine .......... 79 Caecum . 79 Colon 79 Rectum ......... . .79 Mucous Membrane of Large Intestine ...... 79 2* 18 CONTENTS. PAGE Liver ............ Gall-bladder 82 Spleen 82 Pancreas 82 CHAPTER IV. ORGANS OF RESPIRATION. Larynx 83 Trachea ............ 86 Thyroid Gland . .86 Thymus Gland . 86 Lungs 87 Pleurae 89 CHAPTER V. URINARY AND GENITAL ORGANS. Kidneys 89 Supra-renal Capsules . . . 91 Bladder ......... 91 Urethra ............ 92 Prostate Gland .......... 93 Cowper's Glands 93 Penis 94 Testes 95 Vesiculae Seminales ......... 96 Spermatic Cord . . . . . . . . . .96 Descent of Testes 97 ORGANS OF GENERATION IN THE FEMALE 97 Ovaries 97 Fallopian Tubes . . .98 Uterus 98 Vagina 99 Urethra in the Female 100 Mammary Glands lol CHAPTER VI. ORGANS OF CIRCULATION. HEART 101 PERICARDIUM 104 CONTENTS. 19 PAGE J^iTERIES . . .104 Aorta 104 Pulmonary Artery 105 Coronary Arteries ......... 105 Innominata 106 Primitive or Common Carotid ....... 106 .External Carotid 106 Internal Carotid 108 Snbclavian Artery 108 Vertebral Artery 109 Thyroid Axis 110 Internal Mammary ......... 110 Superior Intercostal ......... 110 Axillary Artery 110 Brachial Artery Ill Radial Artery 112 Ulnar Artery 113 Thoracic Aorta 113 Abdominal Aorta 113 Coeliac Axis . . . .114 Superior Mesenteric . . . . . . . . .114 Inferior Mesenteric . . . . . . . . .114 Supra-Renal Arteries ........ 114 Renal or Emulgeut Arteries 114 Spermatic 115 Phrenic 115 Lumbar Arteries . . . . . . . . .115 Middle Sacral Artery 115 Common Iliac .......... 115 Internal Iliac 115 Sciatic Artery . . . ng Gluteal Artery 116 Ilio-lumbar . . . . . . . . . . H(j Lateral Sacral . . . . . . . . . .116 External Iliac Artery 116 Epigastric Artery . . . . . . . . .117 Circumflex Iliac 117 Femoral Artery . . . . . . . . . .117 Popliteal Artery ........ 119 Anterior Tibial Artery 119 Posterior Tibial . . . . . . . . . .120 Peroneal Artery ........ 120 Plantar Arteries 120 20 CONTENTS. PA OR VEINS 120 Exterior Veins of the Head 121 Veins of the Neck 122 Veins of the Interior of the Skull . . . . . .122 Veins of the Arm and Hand . . . . . . . 123 Veins of the Thorax 124 Spinal Veins % . . .125 Veins of the Lower Extremity . . . . . . . 125 Portal System 127 Pulmonary Veins . . . . . . . . .127 Cardiac Veins 128 LYMPHATICS ........... 128 LEFT THORACIC DUCT 128 RIGHT THORACIC DUCT 129 CHAPTER VII. THE SKIN. The Nails 130 The Hair 130 Glands of the Skin 131 Connective Tissue .......... 131 Fat . 131 CHAPTER VIII. MUSCLES. Muscles of the Head and Face 134 Muscles of the Neck 138 Muscles of the Trunk 143 Muscles of the Shoulder . . . . . . . . .151 Muscles of the Arm 151 Muscles of the Forearm 152 Anterior, Superficial Layer 152 Deep-seated Anterior Layer . . . . . . .153 Posterior Region 153 Superficial Layer 153 Posterior Deep-seated Layer 154 Muscles of the Hand 155 Muscles of the Pelvis and Thigh 156 Muscles of the Leg 159 CONTENTS. 21 CHAPTER IX. NERVOUS SYSTEM. PAGE THE BRAIN . . . ' 163 Membranes .......... 163 Dura Mater 163 Arachnoid .... ...... 164 Pia Mater 164 Brain or Encephalon ........ 164 Cerebrum 164 Cerebellum 169 Medulla Oblongata 170 SPINAL CORD 171 Membranes 171 Fissures of the Cord 171 Columns 172 Structure of Cord 172 Origin of Spinal Nerves 172 CRANIAL OR CEPHALIC NERVES ........ 172 Olfactory, 172 Optic, 173 Motor Oculi, 173 Pathetic, 173 Trifacial, 173 Abducens Oculi, 176 Facial, 176 Auditory, 177 Glossopharyngeal, 177 Pneumogastric, 178 Spinal Accessory, 179 Hypoglossal, 179. SPINAL NERVES 180 Cervical 180 Median Nerve 183 Ulnar Nerve 184 Musculo- spinal Nerve 185 Radial Nerve 185 Dorsal Nerves 186 Intercostal Nerves 186 Lumbar Nerves ......... 186 Lumbar Plexus 187 Anterior Crural Nerve ........ 187 Sacral and Coccygeal Nerves 187 Sacral Plexus . 188 Great Sciatic Nerve 188 SYMPATHETIC NERVE ....... . 190 Cephalic Ganglia ; Ophthalmic, Otic, and Submaxillary . . 191 Cervical Ganglia ......... 192 Cardiac Plexuses 193 Thoracic Ganglia 194 Solar Plexus ... 194 22 CONTENTS. PAGE Lumbar Ganglia . 195 Pelvic Ganglia and Hypogastric Plexus 195 CHAPTER X. ORGANS OF SPECIAL SENSE. The Eye 196 Appendages of the Eye . . . . . . . . .199 The Ear * 199 The Nose 202 CHAPTER XI. ANATOMY OF HERNIA . . .202 CHAPTER XII. ANATOMY OF THE PERINEUM . 204 ANATOMY Anatomy is the science of the structure of the human, or of any other, organized body ; of all the parts or organs of which it is composed, and their relative positions in it. Comparative Anatomy includes the study of the organization of other animals with that of man. General Anatomy, Histology, and Microscopic Anatomy study the plan of structure of the body, the tissues of which it is com- posed, and its minute elements. Special or Descriptive Anatomy gives account of the particular organs and all their relations. Regional or Surgical Anatomy takes into consideration the local relations of important parts, especially with a view to surgical operations. In Descriptive Anatomy, the different organs may be studied as follows ! 1. Bones ; 2. Articulations ; 3. Viscera ; 4. Vessels ; 5. Tegument; 6. Muscles; 7. Nerves; 8. Organs of Sense. CHAPTE& I. " ; > BONES. OSSEOUS TISSUE. Composition. IN bone, earthy and animal constituents are intimately combined. / Of the former there are 66.7 parts to 33.3 of the latter. Phos-^ phate of lime is the most abundant mineral material; being about 51 parts in the 100 of bone. Carbonate of lime 11.3 parts; J fluoride of calcium 2 parts. The animal matter of bone is gela- tinous, allied to cartilage ; originally every bone is developed from * cartilage, by ossification. The mineral matter of bone increases with age ; making the >/ ANATOMY. bones of the old more brittle. There is more of it also in somi bones, and parts of bones, than in others. Structure. Bones are long, thick, or flat in shape. In the long bones espe Fig. 1. HUMAN SKELETON. Ligaments removed from the right half; remaining on the left. STRUCTURE. 25 TRANSVERSE SECTION OF AN OLD TIBIA. (Magnified.) cially, we distinguish a compact and a cellular structure; the latter at the ends, which are expanded. The shaft of a long bone, which is hollow, is called its diaphysis ; each end, an epiphysis ; any other projection, a process or apophysis. When a bone is cut transversely, we see distinctly, with the aid of a microscope, canals (of Havres) running in the direction of its length, and communicating laterally, through radiating lesser channels, with minute reservoirs called the corpuscles of Purkinje. The nutrition of the bone is secured, by the Fig. 2. liquor sanguinis or blood-lymph passing through these canals and cells, from the branches of the artery or arteries, which do not penetrate to nearly all its parts. The foramina or holes upon the sur- faces of bones are for their vessels. j By the shaft of the'' long bones being of compact substance, and hollow, while the ends are cellular and enlarged, the greatest strength is obtained, with economy of ma- terial; while the articulations are thus adapted for motion as well as support. The principle of the hollow shaft is illustrated else- where, in nature, in the stems of the grasses; and in art, in the tubular bridge. /The marrow of bones is a peculiar fatty substance. Bones are*/ covered closely, and lined, by the external and internal periosteum. This is a delicate and yet firm membrane, supplied with blood- vessels, and of great importance to the development, nutrition,^ and repair of the bone itself. Development. In the foetus, bones commence their formation in temporary cartilages; in these, as they grow, osseous matter is deposited at and around the points or centres of ossification; which are different in number according to the complexity of the bone. Short bones may have but one such centre. The bones have one for the shaft or diaphysis, and one for each epiphysis. The junction between the ends and shaft occurs at puberty or during adolescence. Some flat bones, as the frontal, and those of the pelvis, are in early life in separate parts, which afterwards are consolidated together. Bones continue to undergo absorption and renewal of their particles through life ; as interesting experiments upon animals have shown. 3 v ANATOMY. Number. In the adult skeleton there are 206 bones, exclusive of the sesamoid and wormian bones, which are not uniform in number. They are, of the Cranium . . . Bones of the ear . Face .... Os hyoides, and sternum Ribs .... Upper extremities . Lower extremities . b' . 14 . 2 . 24 . 64 . 62 206 The most convenient classification of the parts of the skeleton is into the Head, Trunk, and Extremities. The divisions of the Trunk are, the Spine, Thorax, and Pelvis. THE SPINE. In man, the spinal column has four curves ; it is convex anteriorly in the neck, concave in the thorax, convex again in the lumbar region, and concave in the pelvis. It is smaller above, the bodies of the vertebra increasing in size almost regularly from the neck to the sa- crum. The vertebrae are separated from each other by the inter vertebral iges, but firmly connected by ligaments. The spinal cord is con- tained within, and protected by, the spinal column ; the nerves and blood- vessels of the cord passing through the intervertebral foramina. There are 24 true, and 4 or 5 "atse vertebrae. Those called false are scarcely movable; viz., the sa- crum, and 3 or 4 bones of the coccyx. Each vertebra has a body and 7 LATERAL VIKW op THE SPINAL COLUMN. 1. Atlas. 2. Dentata. 3. Seventh cervical verte- bra 4. Twelfth loi sal vertebra. 5. Fifth lumbar vertebra. 6. First piece of sacrum. 7. Last piece of sacrum. 8. Coccyx. 9. A spinous process. 10, ID. Intervertebral foramina. SEVEN CERVICAL VERTEBRA. 27 processes. The processes are, 1 spinous, pointing backwards ; 2 transverse ; and 4 oblique or articulating processes. Of the last, 2 are above and 2 below. The body of the vertebra is in front of the foramen for the spinal cord. v Seven Cervical Vertebrae. Small bodies; spinous processes thick, short, straight, and bifid at the end. Transverse processes have each a foramen for the vertebral artery. Oblique pro- cesses oval, the superior ones Fi S- 4. looking upwards and back- wards, the inferior, downwards and forwards. The spinal fora- men is larger in the cervical than in any other portion of the spine, for free motion of the neck without injury of the cord. The first vertebra, Or atlas, THE ATLAS 1. Anterior tubercle. 2. Arti- 1S a bony ring merely, With cular face for the dentata. 3. Posterior surface only a tubercle in place of the of spinal caaaL 4 ' 4 - Intervel>tebral notch - * . , Transverse process. 6. Foramen for vertebra spinous process ; long trans- artery 7 Superior oblique procegs- 8 Tu _ Verse processes ; Upper Oblique bercle for the transverse ligament. processes, large and concave, to receive the condyles of the occi- pital bone. The lower oblique pro- cesses are round and flat. Its spinal foramen is the largest of all. The second, vertebra dentata, or axis, has the odontoid or dentate process rising from its body to enter the ring of the atlas, where it is con- fined by a ligament. Its spinous process is long and bifid. The sixth and seventh cervical vertebra? are remarkable for the length of their spinous processes ; that of the seventh is the longest. The foramen in its transverse pro- .CeSS Only gives passage tO the VCr- of the intervertebral notch. 5. Infe- tebral Vein ; not tO the artery. rior half of the intervertebral notch / 6. Spinous process. 7. Articular face Twelve Dorsal Vertebrae/. Bodies diminish in diameter from K^SSST 1st to 3d, then increase to the last. The 1st, llth, and 12th have each a complete mark or fossa for a rib. Each of the others receives part of the end of one rib Fig. 5. ri or face of the body. 4. Superior half for the tubercle of a rib. 8. Two su- 9. Two in- 28 ANATOMY. above, and part of the end of another below. The oblique pro- cesses, so called, are perpendicular; the upper one looking back- wards, and the lower ones forwards. Transverse processes long, with marks in front for the junction of the ribs ; except the llth and 12th. Spinous processes long, pointed, and overlapping, as if pressed downwards. Five Lumbar Vertebrae. Large bodies, especially so in transverse diameter. Articulating processes vertical, upper ones looking inwards, lower ones out- wards, so as to interlock the verte- bra. Transverse processes long and straight. Spinous processes short, straight, thick. Sacrum. A wedge-shaped bone, with its base above; concave in front, con- vex and rough behind. Being formed of five vertebras compac- ted together, the marks of their union exist ; incomplete spinous VIEW OP A LUMBAR VERTEBRA.I. and oblique processes and fora- race for the intervertebrai substance, mina, four in front and four behind, 2. Anterior surface of the body. 3. Spi- on eacn s jd e> for the nerVCS. The nous process. 4. Transverse process. j^j mam)W ( cau da equma) IS 5. Oblique process. 6. A portion of the .. , . , i A i bony bridges. 7. The spinal foramen. Continued into a Canal in the Sa- crum. The base of the sacrum closely resembles a lumbar vertebra. Its sides are rough, for junc- tion with the ilia. Its apex has a surface for articulation with the coccyx. Os Coccygis. The coccyx consists of either three or four small bones, which frequently in the adult are united into a firm piece with the sacrum. They diminish in size from the first to the last. THE HEAD. There are, of the cranium, eight bones ; of the /ace, fourteen. CRANIUM. The eight bones are, the frontal, two parietal, two temporal, occi- pital, sphenoid, and ethmoid. Each is composed of an external and internal table, and a diploe, or cellular structure between these. FRONTAL BONE OCCIPUT. 29 Frontal Bone. Convex outside ; on each side in front a slight, round protube- rance, marking the puncta ossificationis ; the orbitar ridge on either side below, terminating externally in the external angular process, and on the nasal side in the internal angular process. Below and between the internal angular processes is the nasal spine. The or- bitar processes, passing backwards from the orbitar ridges, roof the orbits of the eyes. The internal surface of this bone has marks for the convolutions of the brain, and, along its middle, a ridge for the connection of the dura mater, and a fossa for its superior longitudinal sinus ; the fora- men caecum is the passage for the vein in which this sinus begins. The frontal sinuses are cavities, above the orbitary ridges, between the tables of the bone, and communicating with cavities in the eth- moid bone. They vary in size. The most notable foramen of this bone is the supra- orbital fora- men, which is sometimes only a notch, over the middle of each brow ; it transmits the supra-orbital artery and nerve. The frontal bone articulates with the two parietal, the sphenoid, ethmoid, nasal, upper maxillary, lachrymal, and malar. This bone is double, laterally, in infancy ; the two halves uniting into one as life advances. Two Parietal Bones. These are four-sided bones, forming the lateral walls of the skull. The parietal protuberance, on each, marks the point of ossification. The lower portion, outside, is overlapped by the squaraous portion of the temporal bone. Between the upper edges of the two parietal bones is formed the groove for the superior longitudinal sinus of the dura mater. Behind, the parietal bones connect with the occiput ; below and in front, by an angular projection, with the sphenoid; in front and above, with the frontal. Internally, these bones show marks of convolutions of the brain, and others for the middle artery of the dura mater. Occiput. Of rounded form, between and below the parietals, this bone forms the back of the head. It is the thickest of the cranial bones. Outside, is the external occipital cross; within, a corresponding infernal cross. The foramen magnum occipitis is a large opening for the spinal marrow, vertebral artery, and spinal accessory nerves to pass through. Anterior to it is the basilar process, going forwards to join with the sphenoid bone. The condyloid processes are on each side of the foramen magnum, resting upon the atlas. 3* 30 ANATOMY. Fig. 7. The anterior condyloid foramen transmits the ninth or hypo- glossal nerve ; through the posterior condyloid foramen a vein passes to the lateral sinus of the dura mater. The cross on the internal surface of the occiput is very promi- nent, giving origin to grooves for sinuses of the dura mater. The posterior lobes of the cerebrum rest upon the superior portions of the concavity of the bone, as marked by the cross ; the two halves of the cerebellum are supported by the inferior portions. The occipital bone articulates with the two parietal, the sphenoid, and the two temporal. The jugular eminence is on its lower edge, on each side. Before this is the fossa, which by union with the temporal bone is converted into the posterior foramen lacerum ; through this pass the eighth nerves and the internal jugular vein. Two Temporal Bones. Each of these is composed of a squamous, mastoid, and petrous portion. The squamous part is thin, and partly overlaps the parietal bone. The temporal artery grooves its external surface ; which is covered by the temporal muscle. The zygoniatic pro- cess projects forward from the middle of the exterior of the bone, to form the zygo- matic arch with a process of the malar bone. Beneath the base of this process is the glenoid cavity for the articulation with the inferior maxillary bone. Just behind this cavity is the Gla- seri an fissure ; back of this, a fossa containing part of the parotid gland. The laxator tympani muscle, and nerve called chorda tympani, pass through the fissure. The middle artery of the dura mater marks deeply the internal surface of the squain- ous portion of the temporal bone. The mastoid (nipple-like) part is behind the ear. It is of a cellular structure, with dentate edge. Outside are the mastoid process and digastric fossa; inter- nally, above, the mastoid foramen; through which passes a vein. The shape of the petrous portion is that of a pyramid, pointing LEFT TEMPORAL BONE. 1. Squamous portion. 2. Mastoid portion. 3. Petrous portion. 4. Zy- gomatic portion. 5. Tubercle. 6. Temporal ridge. 7. Glenoid fissure. 8. Mastoid foramen. 9. Meatus auditorius externus. 10. Fossa for digastric muscle. 11. Styloid process. 12. Va- ginal process. 13. Glenoid foramen. 14. Groove for Eustachian tube. SPHENOID BONE. 31 inwards and forwards. The name is given on account of its hard- ness. It has a base, apex, inferior, anterior, and posterior sur- faces. In the base is the external meatus auditorius, surrounded by a rim for the attachment of the aural cartilages. In the apex is an opening at the end of the canal for the internal carotid artery. The Eustachian tube is completed by the junction between the apex and the squamous part of the bone ; the tensor tympani muscle passes above it. On the anterior surface is a groove and a foramen, hiatus Fallopii, for the superficial petrous branch of the vidian nerve; also an emi- nence from the bulging of the labyrinth of the ear. The superior petrosal sinus marks the internal edge ; the ganglion of Casser rests upon a depression near .the apex. From the inferior surface goes downwards and forwards the styloid process. The stylo-mastoid foramen is between it and the mastoid portion. The facial part of the seventh nerve, a small branch of the fifth nerve, and the stylo-mastoid artery pass through the stylo-mastoid foramen. Towards the occiput is the jugular fossa ; which, when joined to the occipital bone, makes the posterior foramen lacerum. Through this pass the eighth nerve and jugular vein. Into it opens the tympanic canal, with the nerve ofJacobson. The carotid canal winds through the petrous portion, beginning in front of the jugular fossa. In it, besides the carotid artery, is the ganglion of Laumonier. The opening for the aqueduct of the cochlea is between the carotid canal and the jugular fossa. In the middle of the posterior surface is the internal meatus auditorius. A notch or foramen above this transmits a small artery. The aqueduct of the vestibule opens upon this surface. Sphenoid Bone. This acts as a girder in the architecture of the skull, crossing its base, and holding all of the other bones together. It has a body, four wings, and two descending processes. On the upper surface of the body is the sella turcica (turkish saddle), in which rests the pituitary gland. Behind and over this is the posterior clinoid process ; at the sides pass the sulci carotid, for the carotid arteries. The olivary process is a prominence anterior to the sella turcica, and having upon it a mark for the chiasm or junction of the optic nerves. The nasal lamella of the ethmoid bone articulates with a ridge upon the front of the body of the sphenoid. On each side of this ridge, in the adult skull, is an orifice, belonging to one of the sphenoidal cells, which communicate with the posterior ethmoidal cells. The azygos process on the lower surface of the body of the sphenoid joins with the vomer. 32 ANATOMY. Behind, the sphenoid articulates, by a rough surface, with the cuneiform process of the occiput. Fig. 8. ANTERIOR AND INFERIOR SURFACE OF THE SPHENOID BONE.!, 1. Apophysosof Ingrassias. 2, 2. The great wings. 3. Ethmoidal spine. 4. Azygos process. 5. Sphenoidal cells, after removal of pyramids of Wistar. 6. Posterior clinoid processes. 7. Sphenoidal fissure. The greater wings of the sphenoid have each three surfaces, the temporal, orbital, and cerebral. The temporal is external ; it has a process anteriorly, and is traversed by a ridge. The temporal and external pterygoid muscles lie over it. The orbital or anterior surface contributes a large space to the orbit of the eye. Above, by a triangular serrated portion, this connects with the frontal bone. The temporal bone joins it at the side. On the concave cerebral surface are marks for the convolutions of the middle lobe of the cerebrum. Through it, by the foramen rotundum, passes the second branch of the fifth pair of nerves. The third branch of the fifth goes through the foramen ovale. The spinous process terminates this surface behind ; and through it, by the foramen spinale, passes the middle artery of the dura mater. The lower point of the spinous process is called the styloid pro- cess of the sphenoid bone. The sphenoidal fissure lies between the greater and the lesser wings. Through it pass the third, fourth, first branch of the fifth, and sixth pairs of nerves. The lesser wings, or apophyses of Ingrassias, are in front of the greater, and are three-sided. Posteriorly they present the anterior clinoid processes ; through these pass, by the optic foramina, the optic nerves and ophthalmic arteries. The frontal bone articulates with these processes anteriorly. Downward, on each side, project the pterygoid processes. In front, these join with the palate bones. Behind, they present the ETHMOID BONE. 33 Fig. 9. pteryg oid fossa and notch, by which each process is divided into two plates, the internal and external. The internal is longer ; at its end is the hamulus, a hook-like process over which runs the tendon of the circuraflexus palati muscle. The internal pterygoid muscle originates upon this internal plate. The external pterygoid muscle has its origin in the external plate of the pterygoid pro- cess, which is broader than the internal. Through the base of the process goes the pterygoid foramen ; which conveys the Vidian or recurrent nerve, a branch of the fifth. The sphenoid bone articulates with each of the other bones of the palate and vomer of the face, and with the molar. Ethmoid Bone. A light, cellular bone, at the base of the skull, below the fron- tal and in front of the sphenoid bone. Its general shape is cuboid. Above, it presents the cribriform plate, through the orifices of which pass the filaments of the first or olfactory nerve ; through the anterior and largest foramen goes the internal nasal branch. The crista galli is an upright process or crest from the middle line of the cribriform plate. The falx cerebri is attached to it. In front, it joins the frontal bone. The foramen caecum is here formed, between the two bones ; it transmits a small vein. The perpendicular plate, or nasal la- mella, descends from the middle of the cribriform plate, and constitutes part of the septum of the nose. It articulates with the vomer below. Each outer surface of the ethmoid is called os planum. It forms part of the orbit of the eye, and joins above with the frontal bone, below, with the superior maxillary and palate bones, in front with the lachrymal, and behind with the sphenoid. It has two foramina above, one of which transmits the internal nasal nerve. Below each os planum projects downwards and backwards the irregular unciform or hook-like process ; which joins with the inferior turbinated bone. The superior and middle turbinated bones are curved or scroll- like processes within the ethmoid, seen best from behind. They are attached to the inside of the lateral masses of the bone. The anterior cavities of the nose are thus formed and subdivided. The fissure between the superior and middle turbinated bones is the UPPER AND POSTERIOR VIEW OF THE ETHMOID BONE. 1. Nasal lamella. 2. Body or cellular por- tion. 3. Crista galli. 4. Cribri- form plate. 5. Superior rneatus. 6. Superior turbinated bone. 7. Middle turbinated bone. 8. Os planum. 9. Surface for tlie olfac- tory nerve. 34 ANATOMY. superior meatus of the nose. That beneath the middle, between it and the inferior turbinated bone, is the middle meatus. Into the latter empty the anterior ethmoidal cells ; the frontal sinuses are connected with the latter. Into the superior meatus empty the sphenoidal sinus and the posterior ethmoidal cells. The pyramids of Wistar, or of Bertin, are hollow, three-sided processes, the bases of which are attached to the superior turbi- nated bones, the cribriform plate and the nasal lamella, posteriorly. The apices, or points of the pyramids, lie one on each side of the azygos process of the sphenoid. These pyramids are connected with the ethmoid bone only during childhood ; afterwards they form the walls of the sphenoidal sinuses. Besides the frontal and sphenoid, the ethmoid bone articulates with eleven of the facial bones. BONES OP THE FACE. These are fourteen in number, all belonging to the superior maxillary region, except the single bone of the lower jaw. They are the two upper jaw bones, two nasal bones, two palate bones, two malar bones, two ossa ungues, or lachrymal bones, two inferior turbinated bones, the lower jaw bone, and the vomer. The Malar Bones. Quadrangular and prominent, forming the cheek bones. Each has an outer and inner surface, four processes, the frontal, orbital, maxillary and zygomatic, and four edges, superior, inferior, ante- rior, and exterior. The outer surface is convex, the inner concave ; each has small foramina for vessels and nerves. To the inner, the temporal and masseter muscles are attached ; to the outer, the two zygomatic muscles. The frontal process joins with the frontal bone. The orbital process passes backwards to form part of the outer wall of the orbit ; joining the greater wing of the sphenoid. The spheno-maxillary fissure, or foramen lacerurn inferius, is bounded by an edge of the orbital process. The maxillary pro- cess articulates with the malar process of the upper jaw bone. The temporal process passes backwards to join the zygomatic process of the temporal bone in forming the zygomatic arch. To the posterior edge of the malar bone the temporal fascia is attached. Two Superior Maxillary Bones. Each is irregular in shape, with four surfaces, four processes, and a large cavity within the body. Each forms part of the floor of the orbit, the roof of the mouth, and the floor and outer wall of the nose. The external is the facial surface. Above the de- pression called the canine fossa, and near the upper edge of the TWO NASAL BONES. 35 Fig. 10. SUPERIOR MAXILLA. 1. Antrum. 2. Due- tus ad nasum. 3. Articular surface for os froutis. 4. Articular surface for nasal bone. 5. Surface for nasal cartilage. 6. Floor of the nostril. 7. Surface for the bone of ^the right side. 8 Foramen incisivum. 9. Palate plate. 10. Surface for palate bone. 11. Ridge for the iuferior spongy bone. 12. Articular facial surface, is the infra-orbital foramen; through which pass the infra-orbital artery, vein, and nerve. The posterior surface is con- vex ; its greatest prominence is below, the maxillary tuberosity ; within, this joins with the palate bone. The posterior dental ar- tery, vein, and nerve go through its foramina. The orbital surface is supe- rior ; it is three-sided. The nasal or internal surface pre- sents the opening into the antrum highmoriamim, or maxillary si- nus. The junction of the eth- moid, palate, and inferior turbi- nated bones narrows this open- ing very much. The cavity is somewhat pyramidal in shape ; its base being the outer wall of the nose. The malar process is Irian- 8urface for palate bone behind - is. surface , f~ * . , for nasal plate of palate bone. 14. Surface gular and rough, for union with for orbitar plate of palate bone 15 Nasal the malar bone. The nasal pro- a uct . cess rises to form part of the side of the nose. It joins with the nasal bone in front, the frontal bone above, and, behind, having a groove in common for the lachrymal sac, with the os unguis. The alveolar process is thick and spongy ; it contains sockets for eight teeth, incisor, canine, and molar. The palate processes make the roof of the mouth. From the median junction of the two arises the nasal crest; which articu- lates with the vomer. The nasal spine is at the front of this. Just behind it is Ike foramen incisivum ; in which are the ganglion of Cloquet and the naso-palatine nerve. Posteriorly, the palate processes unite with the horizontal plates of the palate bones. Two Nasal Bones. These are long and irregularly four-sided ; thick and narrow above, where they join the frontal bone ; thin and wide below, for the attachment of the cartilages of the nose. Externally, they are inclosed by the nasal processes of the two superior maxillary bones ; internally, they articulate with each other. The posterior surface has a groove for the internal nasal nerve. The inner ANATOMY. Fig. 11. THE NASAL CAVITIES.!. Part of cranium. 2. Crest of ethmoid. 3. Ethmoid bone. 4. Middle of ethmoid. 5. Vomer. 6. Middle tur- binated bone. 7. Inferior turbiiiated bone. 8. Malar bone. 9. Antrum. border has a crest for junction with the nasal spine of the fron- tal above, and with the perpen- dicular plate of the ethmoid, below. Two Lachrymal Bones. Also called ossaungues,from resemblance to finger-nails. They are located at the front part of the inner wall of the orbit. A vertical ridge divides the orbital surface into two por- tions. In front is the ungual part of the lachrymal groove, completed by the nasal pro- cess of the superior maxillary. In the upper part of this groove lies the lachrymal sac; The ridge gives origin to the tensor in the lower, the nasal duct. tarsi, or Homer's muscle. The lachrymal bones articulate with the frontal, ethmoid, supe- rior maxillary, and inferior turbinated bones. Fig. 12. THE PALATE BONE 1. Pal- ate plate on its nasal surface. 2. Nasal plate. 3. Pterygoid process. 4. Surface for arti- culating with its fellow. 5. Half of the crescentic edge and spine for the azygos uvu- Ise muscle. 6. Ridge for the inferior spongy bone. 7. Spheno-palatine foramen. 8. Orbital plate. Two Palate Bones. Irregular; formed chiefly in two portions. The horizontal plate on each side completes the roof of the mouth and palate, by junc- tion with the palate processes of the upper jaw bone. Part of the nasal crest which articulates with the vomer is formed at the junction of the two plates. Behind, in the same line, is the posterior nasal spine. From this, the azygos uvula? muscle arises. The vertical plate articulates internally, by a ridge, with the inferior turbinated bone ; externally, with the superior maxil- lary. In the latter articulation is the pos- terior palatine foramen, for the palatine artery and nerve. The pterygoid process is behind and be- low. It is triangular, and receives the two plates of the pterygoid process of the sphenoid bone. The spheno-palatine foramen is formed by a notch between the processes at the VOMER TWO INFERIOR TURBINATED BONES. 3t upper part of the vertical plate being completed by junction with the sphenoid bone. Through this foramen pass the spheno-pala- tine artery and nerve. Anteriorly, and above, is the orbitar process, which passes between the superior maxillary and the ethmoid, to contribute a small portion to the orbit of the eye. The other process passes backwards, at the top of the vertical plate ; it is called the ptery- goid apophysis, and joins the sphenoid bone. Vomer. The posterior nares are divided by this bone ; which is flat, thin, and vertical in position, with its antero-posterior diameter the longest. Its upper border is thickest, and articulates with the sphenoid. Its anterior border joins in front with the triangular cartilage of the nose, and, behind this, with the ethmoid. The inferior border articulates in front with the superior maxillary bones, and further with the palate bones. The posterior border is concave, thin-edged, and free. + Two Inferior Turbinated Bones. Small, spongy, scroll-shaped, one on each side of the nose, within the fossa, attached to its outer wall. Its internal convex Fig. 13. LEFT NASAL FOSSA. 1. Frontal bone. 2. Nasal bone. 3. Superior maxillary. 4. Sphe- noid. 5, 6, 7. Superior, middle, and inferior turbinated bones. surface is covered by the lining membrane of the nose ; its exter- nal surface is concave, and forms part of the inferior meatus. 38 ANATOMY. Each bone articulates with the ethmoid, superior 'maxillary, palate, and lachrymal bones. Inferior Maxillary Bone. This consists of the body, horizontal and convex anteriorly, and two perpendicular rami. In the median line of the body is the ridge of the symphysis, where join the two parts in which the bone is developed. At the base of this ridge is the triangular mental process. Each side of the symphysis is the incisive fossa ; outside of this, the mental foramen, through which pass the mental artery and nerve. The internal surface is marked by the four genial tubercles, for muscular insertions. Near them are fossae for the sublingual glands. The superior border is hollowed out for the sockets of sixteen teeth, in the adult. Each ramus is four-sided, with two prominent processes above. Its flat external surface is covered by the masseter muscle. Its internal surf ace has the aperture of the inferior dental canal, for the nerve and vessels of the same name. This canal passes into the substance of the body of the bone, to distribute nerves and vascular branches. The condyloid process is short and thick, with a condyle for articulating with the temporal bone, and below this, a neck. The coronoid process is flat, thin, and triangular; anterior to the condyloid, with the sigmoid notch between them. It is the point of attachment of the temporal muscle. General Remarks on the Head. The Sutures. These are the somewhat irregular and generally serrated lines of articulation of the bones of the head. The prin- cipal are the coronal, sagittal, squamous and lambdoidal sutures. The coronal suture is between the frontal and the two parietal bones, across the head above. The sagittal suture is between the two parietals, passing longi- tudinally. The squamous suture connects the temporal with the parietal and sphenoid bones. It is rough and undulated rather than serrated. The lambdoidal suture (named for the Greek letter lambda) is between the parietal bones and the occiput. It is formed of two limbs separating at an angle. JDiploe. This is the cellular bony structure between the outer and the inner tables of the skull. Branching canals through it contain veins. The outer table of the bones of the skull is the strongest and least brittle. In infancy they are closely conneclud with but little diploe. GENERAL REMARKS ON THE HEAD 39 Fig. 14. Exterior Regions of the Head. . These are the coronal region, the facial, the two lateral, and the basal region. The coronal region is seen in a vertical view of the cranium in its natural position. The facial region is bounded by the parietal protuberances, the zygoraatic arches, the coronal suture, and the margin of the lower jaw. The lateral regions are con- tained between the temporal ridge above, the margin of the orbit front, and the lambdoidul suture behind. The base of the skull is very irregular and complex; capable of being studied to advantage only with a specimen or plate. Its general outline is oval. Its principal foramina are, tlie/ora- men magnum occipitis, foramen incisivum, posterior palatine foramen, foramen lacerum ante- rius, foramen lacerum posterius, and the special foramina of the sphenoid bone. Interior Regions of the Cra- nium. The calvaria, or vaulted roof of skull, is generally smooth within, though marked for the convolutions of the brain, and also by a groove for the longitudinal sinus of the dura mater, and de- pressions, on each side of the sagittal suture, for the glands of Pacchioni. The base of the cranium, within, exhibits three regions, anterior, middle, and posterior. The anterior fossa lodges the anterior lobes of the cerebrum; the middle fossa the middle lobes of the same; while the pons Varolii, medulla oblongata, and cerebellum are con- tained in the posterior fossa. The Orbit. The cavity for the eye is a somewhat quadrangular pyramid, formed of seven bones ; the frontal, superior maxillary, malar, sphenoid, ethmoid, palate, and lachrymal bones. Nasal Cavities. (See fig. 11.) These are contained between the cribriform plate of the ethmoid and the sphenoid bones above; in front the ossa nasi and cartilages of the nose; below, the pal- ate processes of the superior maxillary and palate bones ; outside, FRONT VIEW OF THE SKULL. 1. Os fron- tis. 2. Nasal tuberosity. 3. Supra-orbital ritlge. 4. Optic foramen. 5. Spheuoidal fissure. 6. Spheno-maxillary fissure. 7. Lachrymal fossa. 8. Opening of the auto- rior nares, and the vomer. 9. Infra-orbital foramen. 10. Malar bone. 11. Symphysis of the lower jaw. 12. Anterior mental foramen. 13. Ramusof the lower jaw-bone. 14. Parietal bone. 15. Coronal suture. 1(5. Temporal bone. 17. Squamous suture. 18. Great wing of the sphenoid. 40 ANATOMY. the superior and maxillary, ethmoid, and inferior tnrbinated hones. Between the two cavities is the septum nm-ium, formed by the voraer, nasal lamella of the ethmoid, and the nasal cartilage. Fig. 15. EXTERNAL VIEW OF THK BASE OF THE CRAMDM 1. Hard palate. 2. Foramen incisivum. 3 Palate plate of palate bone. 4. Cresceutic edge. 5. Voiner. 6. Internal pterygoid pro- cess of sphenoid bone. 7. Pterygoid fossa. 8. External pterygoid process. 9. Temporal fossa. 10. Basilar process. 11. Foramen magnum. 12. Foramen ovale. 13 Foramen spiuale. 14. Glenoid fossa. 15. Meatus auditorius externus. 16. Foramen lucernin aute- rius. 17. Carotid foramen. 18. Foramen lacerum postering 19. Styloid process. 20. Stylo-mastoid foramen. 21. Mastoid process. 22. Condyles of occipital bone. 23. Poste- rior coudyloid foramen. The outlets from these fossae in front, are the anterior wares ; behind, the posterior wares. The passages, nearly horizontal, through the nasal cavities are, the superior, middle, and inferior rneatus. The superior is the smallest. The middle contains the opening into the antrum maxillare. The inferior presents the orifice of the ductus ad nasvm from the lachrymal sac. Ossa Triquetra,or Wormiana. These are small, irregular bones, not always present or of the same shape, included in the sutures, especially the larabdoidal. Fontanels These, most interesting in obstetric anatomy, are places of deficient ossification at the junction of the bones in the head at and for a time after birth. They are the anterior and posterior fontanels, and two smaller ones on each side. Diameters of the Head. In the adult of European race, the GENERAL REMARKS ON THE HEAD. 41 cranium is about six inches and a half in length, five inches in height, and five and a half transversely. Fig. 16. INTERNAL SURFACE OF THE BASE OF THE CRANIUM.!. Anterior fossa for anterior lobes of the cerebrum. 2. Lesser wing of the sphenoid bone. 3. Crista galli. 4. Foramen caecum. 5. Cribriform plate. 6. Processns olivaris. 7. Foramen opticum. 8. Anterior clinoid pro- cess. 9. Groove for the carotid artery. 10. Greater wing of the sphenoid bone. 11. Mid- dle fossa for middle lobes of the cerebrum. 12. Petrous portion of temporal bone. J3. Sella turcica. 14. Basilar gutter for the medulla oblongata. 15. Foramen rotuudurn. 16. Foramen ovale. 17. Foramen spinale. 18. Posterior fossa for the cerebellum. 19. Groove for the lateral sinus. 20. Ridge for the falx cerebelli. 21. Foramen magnum. 22. Meatus auditorius internus. 23. Posterior foramen lacerum for the jugular vein. Internal Capacity. Morton gives, as the average capacity of the Anglo-Saxon and German cranium, ninety cubic inches ; of the native African races, eighty-five inches ; other races coming between. Form of the Head. Dividing the human species into five va- rieties, the head in the Caucasian or European may be described as of a rounded oval shape. In the Mongolian race it is pyra- midal, rising from the prominent cheek bones and almost vertical occiput toward the sagittal suture. In the Malay the same shape of the head is seen, with a broader and flatter face. The head of the American Indian is also like that of the Mongolian, with somewhat greater prominence of the face. The Negro has a skull long antero-posteriorly, with low forehead, full occiput, and prominent maxilla. Facial Angle. After Camper, this is obtained by drawing a line from the anterior margin of the upper jaw to the most promi- nent part of the forehead, and crossing this by a horizontal line 4* 42 ANATOMY. from the external meatus of the ear to the lower edge of the nose. Morton asserts the mean facial angle of the Caucasian race lo be 80; of the Mongolian, 77; of the Malay, American Indian, and Negro, 75. All that the facial angle determines is the pro- portion of development between the head and face. HYOID BONE. Connected in man with no other bone, the os hyoides is attach- ed to the root of the tongue and the larynx. It is shaped like the letter U, or a horse-shoe, the convexity being forward. Be- sides the central body, it has two greater and two lesser cornnu. The greater project backwards, each terminating in a tubercle. The lesser cornua ascend, to the length of a few lines, from the junction of the body and the greater cornua; they are generally cartilaginous. Several muscles and ligaments are connected with this bone. THE THORAX. FRONT VIEW op THE THORAX. 1. First bone of the sternum. 2/ Second bone of Jhe sternum. 3. Third bone or ensiform cartilage. 4. First dorsal vertebra. 5. Last or twelfth dorsal vertebra. 6. First rib. 7. Its head. 8. Its neck. 9. Its tuber- cle. 10. Seventh or last true rib 11. Its cartilage. 12. Angle of eleventh rib. 13. Its body. The sternum, ribs, and dorsal vertebrce inclose the chest. Its shape is that of an imperfect cone, notched in front, below, and flat above, concave behind, and open at the top. Sternum. Composed of three pieces, this bone is flat and oblong. In old age the pieces are consolidated into one. The first or upper piece is the thickest. The clavi- cle on each side articulates with it at the upper cor- ner ; lower down are small cavities for the first rib and part of the second. The second or middle piece is the longest, but is narrower than the first, though widening below. With its sides articulate the cartilages of part of THE PELVIS. 43 tlie second rib, the whole of the third, fourth, fifth, sixth, and part of the seventh. The third piece is often a cartilage only. It varies much in shape, being sometimes bifurcated. It is often called the xyphoid or ensiform cartilage. Part of the cartilage of the seventh rib is attached to its side. Ribs. Twelve on each side ; seven whose cartilages reach the sternum, called true ribs, and jive others below, the false ribs. The last two, with free ends, are called j#oa^'?? CARPUS. The carpus or wrist consists of eight bones, in two rows. The wrist is con- vex posteriorly, concave anteriorly ; through the concavity pass the flexor tendons. The upper row of bones contains the scaphoid, lunare, cuneiform, and pisi- form. The lower row has the trape- zium, trapezoid, magnum and unciform. The scaphoid, or boat-shaped bone, is on the radial side of the upper row. Above, it is convex, to articulate with the end of the radius ; below, concave for the magnum. It also articulates with the lunare, trapezium, and trape- zoid. The lunare, or crescent-shaped bone, 5 ANTERIOR VIEW OF ULNA OF THE LEFT SIDE 1. Olecranon pro- cess. 2. Greater siginoid cavity. 3. Coronoid process. 4. Lesser sigmoid cavity. ft. External sur- face. 6. Ridge for interosseous ligament. 7. Small head for the radius. 8. Carpal surface. 50 ANATOMY. Fig- 23. has a convex upper surface, wlik'h joins the radius, and articulates be- low with the magnum, and at the side with the cuneiform. The cuneiform, or wedge-shaped bone, is joined below to the unci- form, and at the side to the pisiform. It has a round face to meet the latter bone. The pisiform, or pea-shaped bone, is the smallest of the carpus. It unites only with the cuneiform. It forms* a prominence on the palmar face of the wrist, at the ulnar side. The trapezium is many-sided. It articulates with the trapezoid, the scaphoid, and the metacarpal of the thumb. The trapezoid is smallest of the lower row; it has a pyramidal shape, the apex being on the palmar side. The magnum is the largest bone of the carpus. It is four-sided, with a rounded head or tubercle on its dorsal surface. The unciform is remarkable especially for a hooked process on the palmar side. METACARPAL BONES. These are five, one for each digit Each metacarpal has a round lead, to join with the first phalanx below ; a rough four-sided base above, for its carpal articulation ; and a prismatic shaft, on the sides of which the interossei muscles are attached. The longest metacarpal is that of the index or fore-finger. That of the thumb is short and thick. The smallest is that of the little ARTICULATIONS OF BONES OF THE CARPDS. 1. Ulna. 2. Radius. 3. In- ter-articular fibro-cartilage. 4. Meta- carpal of thumb. 5. Metacarpal of first finger. 6. Metacarpal of second finger. 7. Metacarpal of third finger. 8. Metacarpal of fourth finger. S Sca- phoides. L. Lunare. C. Cuneiform. P. Pisiform. T. T. Trapezium and trapezoides. M. Magnum. U. Unci- form. linger. FINGERS. Each finger has a frst, second, 4 and third phalanx; counting from the metacarpal bone. The thumb has but two phalanges. The first phalanx is always the largest, and is convex on its dor- sal surface, flat on the palmar side. A concavity at its upper end receives the round head of the metacarpal bone. Below it pre- sents to the end of the second phalanx two small tuberosities with a groove between them. The second phalanx has at its upper end two concavities with LOWER EXTREMITY FEMUR. 51 a ridge between them ; at its upper end two tubercles with an in- termediate groove, to meet the third. The third phalanx is smallest. Its upper end resembles that of the second ; its lower extremity is thin, rough, and flat. The fore-finger is called the index. The middle and longest finger has been sometimes named the impudicus ; the third, an- nnlaris ; the little finger, auricularis. Sesamoid Bones. Two of these (named from sesamum, oriental barley) are usually in the metacarpo-phalangeal joint of each thumb, connected with the flexor tendon. They are not unfreqnently wanting. Fig- 24. LOWER EXTREMITY. Femur. This, the thigh bone, is the longest of all the bones. It has a head, neck, shaft, and condyles. The head is nearly spherical, to be re- ceived into the acetabulum. Near its middle, above, is a depression for the ligamentum teres. The neck shortens and approaches a right angle in its direc- tion in old age, when it is more liable to fracture. Outside, at the lower end of the neck, is the large process called the trochanter major. The glutens medius, glutens minimus, and other muscles are inserted into this. The trochanter minor is lower and more internal; the iliacus internus and psoas magnus muscles are inserted into it. Into a ridge between the trochanters behind is inserted the quadratus femoris. The shaft of the femur is arched, the convexity being in front. Over its ante- rior surface is the origin of the crnrseus muscle. The linea aspera is a strong ridge up and down the posterior surface of the bone. It has two edges ; to the outer are attached the tendon of the glu- teus maximus, and the muscular origin of the vastus externus and the short head of the biceps. Into the inner edge of the linea aspera are inserted the pectinens and adductor magnus; and from this edge arises the vastus internus. POSTERIOR VIEW OF THE FE- MUR. 1. Depression for round ligament. 2. The head. 3. Depression for rotary muscles. 4. Trochanter major. 5. Tro- chanter minor. 6. Roughness for gluteus maxim as tendon. 7, 7. Linea aspera. 8. Surface for gastrocnemius muscle. 0. External coudyle. 10. De- pression for anterior crucial ligament. 11. Depression for posterior crucial ligament. 12. Origin of internal lateral ligament. 52 ANATOMY. The condyles, internal and external, are at the lower end of the femur, .which widens towards them. The external condyle has upon its posterior face the origin of the popliteus, part of the gastrocnemius and plantaris muscles. The internal condyle is longest. It also gives part origin to the gastrocnemius. Eacli condyle has marks for the crucial and lateral ligaments. The fossa in front of the condyles for the patella receives its largest contribution from the external coudyle. Patella. A flat bone, of a roundish triangular shape, commonly known as the cap of the knee or knee-pan. It is Flg * thickest and widest above, where the tendon of the quadriceps femoris is inserted into it. Below, the continuation of the same tendon, in which (like a sesamoid bone) the patella maybe considered as situated, iscalled the ligament of the patella: this is inserted in the tibia. The knee-pan is covered ante- riorly only by the skin. Tibia. The inner and larger of the two bones of the leg. Its head, or large upper end, pre- sents an oval surface, divided by the up- right spinous process into two parts, each oval, for the condyles of the femur. Pro- jections on each side are called the external and internal condyles of the tibia. At the back part of the external condyle is a small face for the articulation of the fibula. In front, below the head, is a tubercle for the tendon or ligament of the patella. Posteriorly, is the insertion of the popliteus muscle, and the origin of the soleus. Of the body, the inner surface is covered only by skin. The outer surface is occupied by the tibialis anticus and extensor digito- rum. The tibialis posticus and flexor digi- torum arise from its posterior surface. The outer edge of the tibia has attached to it the interosseous ligament. To the upper portion of the rounded inner edge are attached the tendons of the sartorius, semi-tendinosus and gracilis muscles. The lower end of the tibia is smaller ANTERIOR VIEW OP THE TIBIA 1. Spinous process. 2. Surface for condyles of the femur. 3. Face for head of the fibula. 4. The head. 5. The tubercle. 6, 6. Spine and shaft of the bone. 7. Internal malleo- lus. 8. Process for inter- nal lateral ligament of the ankle. 9. Tarsal surface. Id. Face for lower eud of fibula. FIBULA TARSUS, 53 Fig. 26. than the upper. Internally, it presents the internal malleolus or large process of the ankle. Outside, it articulates, by a fossa, with the lower end of the fibula. Between these parts, at the end of the bone, is a concavity which rests and moves, by a hinge-like joint, upon the astragalus. The extensor tendons lie over the anterior surface of the lower end of the tibia ; the tendon of the flexor longus pollicis murks its posterior surface. Fibula. Much more slender than the tibia, this bone is external to it, and, above, somewhat behind it ; not reaching to the articula- tion of the knee. It supports the head of the tibia, having an enlargement or head to articulate with its outer condyle. The biceps flexor cruris is inserted into its sty- loid process. The body of the fibula has three sur- faces ; internal, external, and posterior. The internal or tibial surface presents a long ridge for the interosseous ligament. The extensor cornmunis and extensor pro- prius pollicis arise in front of this ridge ; be- hind it, the tibialis posticus partly arises. The wide external surface is a long spiral, anterior above and becoming poste- rior below. The peroneus longus and pe- roneus brevis muscles arise from the upper portion of this surface, and their tendons pass through a groove on its lower part. On the posterior surface, which is some- what spiral, arise the soleus and flexor longus pollicis muscles. The external malleolus is a long descend- ing process of the lower end of the fibula. It is somewhat triangular, with a pointed termination, the coronoid process, to which the external lateral ligament is attached. Within, the malleolar process articulates with the astragalus. THE FIBULA. 1. Head. 2 Articular face 3. Inser- tion of external lateral liga meat. 4. Shaft. 5, 5? Exter- nal face. 6. Interosseous ridge. T.'Vace for lower end of tibia. 8. Malleolus extenius. 9. Tarsal surface. TARSUS. Seven bones form the tarsus ; the astra- galus, os colds, scaphoid, cuboid, and in- ternal, middle, and external cuneiform. Astragalus. Composed of a head and a body The body is rounded above for 5* 54 ANATOMY. 27. the tibial articulation ; nearly flat at the sides, for the two mal- leoli ; underneath, the body is concave. The anterior part or head is convex in front, and widest trans- versely. A constriction or neck intervenes between the head and the body. Os Calds. This, the heel-bone, is the largest of the tarsus. It articulates above with the astragalus by two surfaces, having between them a groove for the interosseous ligament. Externally the os calcis is covered by skin. The tendons of the peroneus longus and peroneus brevis mark the surface with grooves. On its internal surface is the sinvosify, occupied by tendons, nerves, and bloodvessels going to the plantar region of the foot. Behind, the bone is rough below for the insertion of the tendo Achillis ; above, it is smooth. Underneath, the os calcis has three tuberosities, for ligaments and tendons. In front, are the greater and lesser apo- physes. The greater joins the cuboid bone. The lesser is hook-shaped, passing for- ward and ascending to meet the astragalus. The tendon of the flexor longus pollicis passes through a groove on its surface. Scaphoid. Thickest above, convex in front, concave behind. The anterior sur- face has three facets for the cuneiform bones. The astragalus fits into the posterior deep concavity. The tibialis posticus muscle is inserted into a tubercle on the inner face of this bone. Cuboid. Convex and rough above. Un- derneath, at the end of a ligainentous ridge, is a groove for the peroneus longus tendon. In front, the cuboid articulates with the last two metatarsals ; behind, with the great apophysis of the heel bone ; internally, with the external cuneiform. Internal Cuneiform. Largest of the three. The point of the wedge is uppermost. It is concave externally, convex internally, where it is covered by tegument only. Behind, it joins the sca- phoid by a triangular surface ; in front, it meets the rnetatarsal of the great toe. The tibialis anticus muscle is inserted into the inner side of the rounded base or lower part of the bone. UPPER SURFACE OP THE LEFT FOOT. 1. Astragalus. 2. Its anterior face. 3. Os calcis. 4. Naviculare, or scaphoides. 5. Internal cu- neiform. 6. Middle cunei- form. 7. External cunei- form. 8. Cuboid bone. 9, 9. Metatarsal bones. 10. First phalanx of the big toe. 11. Second phalanx of the big toe. 12, 12, the first ; 13, 13, second ; and 14, 14, third phalanges of the other toes. METATARSAL BONES TOES. 55 Middle Cuneiform. Smallest of the three. The apex of the wedge is downwards. In front, it joins the second inetatarsal, in- ternally, with the internal cuneiform ; externally, with the external cuneiform, and behind with the scaphoid. External Cuneiform. Size intermediate between the two others. The narrow part of the wedge is below. It joins, in front, the third metatarsal ; on its inner side, by two surfaces, the internal cuneiform and second metatarsal ; behind, the scaphoid. Outside, it has a process which joins anteriorly with the fourth inetatarsal bone, and posteriorly with the cuboid. . METATARSAL BONES. Five in number, one for each toe. At their bases they articu- late with the cuboid and cuneiform bones. By rounded heads they join the first phalanges of the toes. The first metatarsal, on the inside, is the thickest and shortest. It articulates by a large base with the internal cuneiform. The peroneus longus tendon is inserted into it. Sesamoid bones are met with in its phalangeal articulation. The second is the longest of all. It articulates with the middle cuneiform behind, internally with the internal cuneiform, exter- nally with the external cuneiform and third metatarsal. The third joins by its base with the external cuneiform, and, outside, by two facets, with the fourth metatarsal. The fourth articulates with the cuboid, and, at its sides, with the third and fifth. The fifth and smallest articulates with the cuboid and fourth metatarsal. From its base projects outwards and backwards a tubercle, which receives the tendons of the peroneus tertius and peroneus brevis muscles. TOES. Each has a first, second, and third phalanx, counting from the metatarsus, except the great toe, which has but two. The first phalanx is always smaller than the first of the corre- sponding finger. Their bodies are narrow, their bases concave, their distal ends have two small convexities with a groove between them. f. The second phalanges have small bodies ; their bases have two concavities with a ridge between ; the anterior ends, two convexi- ties with an intermediate groove. The third phalanges are still smaller. The articulating base has two concavities and a ridge. The extremity is rough and flat- tened. 56 A N A T O M Y . THE TEETIF. Man lias two sets of teeth ; first, twenty small deciduous or milk teeth ; afterwards thirty-two permanent teeth. Of the former, Fig. 28. E'GHT TEETH OF ONE SIDE OF THE UPPKR JAW. 1. Incisors. 2. Cuspids or canine teeth. 3. Bicuspids. 4. First two molars. 5. Dens sapieutia;. Fig. 29. EIOHT TEETH OF ONE SIDE OF LOWER JAW. 1. Incisors. 2. Cuspids or canine teeth. 3. Bicuspids. 4. First two molars. 5. Dens sapieutiie. there are in each jaw four incisors, two canines, and four back teeth or molars. Of the permanent set, in each ja\v,/0wr in front are incisors, two (one on each side) are canines, four (two on each side) are bicuspids or premolars, and six (three on each side) molars. Each tooth has a projecting crown, a neck, and a concealed fang or root. The root is implanted in the alveolus of the jaw ; which is lined with periosteum. The edge of the incisor tooth is cutting, as the name implies; the crown is wedge-shaped ; the fang is long and single. The upper incisors are largest. The canines have a conical, somewhat pointed crown, and a single fang, longer than that of the incisors. The upper ones are largest. The premolar or bicuspid teeth have the surface of the crown divided, not deeply, into two cusps or prominences. Their fangs STRUCTURE OP THE TEETH. Fig. 30. are single, but with a partial division, especially at the apex. The upper ones are larger than the lower. The molars have broad crowns, surmounted by four or five tubercles. The first and second molars have three fangs in the upper jaw, two in the lower; the third (wisdom tooth) has one fang, grooved as though becoming divided into three or two. Structure of the Teeth. Each tooth, in vertical section, shows an interior cavity con- taining the pulp, with the bloodvessels and nerves belonging to it. The solid tooth consists of dentine, enamel, and cementum or crusta pe- trosa. Dentine differs in structure from bone; being shown by the microscope to con- sist of minute wavy and branching toibuli, about 5^00 f an i ncn * n diameter, im- bedded in the dense intertubular tissue. The tubuli are vertical in the summit of the crown, oblique in the neck, and in- clined downwards in the lower part of the neck. Enamel is the hardest part of a tooth. It forms a thin crust over the exposed part of the crown, thinning down to- wards the neck. Microscopic examina- tion shows it to be composed of paral- lel six-sided columns, directed vertically at the summit of the crown, and hori- zontally at the sides. Cementum or crusta petrosa is inter- mediate in compactness between enamel and dentine. It covers the fangs of the teeth. Its structure is like that of bone, having the Haversian canals and lamellae. Chemically, teeth are composed of phosphate and carbonate of lime, traces of fluoride of calcium, and other salts, and a little gelatinoid animal matter. Dentine has seventy-two parts of mineral matter and twenty-eight parts of gelatin. Development of the Teeth. ' In the sixth or seventh week of fcetal life the germs of the milk- teeth begin to form in a groove of the maxillary mucous mem- brane. Calcification of the permanent teeth commences a little before birth ; both sets of teeth being thus in the jaws together, long before their eruption. MAGNIFIED SECTION OF A TOOTIT. 1. Enamel. 2, 7. Cemeutum. 3. Ivory. 4. Foramen. 5. Den- tal cavity. 6. Osseous corpus- cles. 58 ANATOMY. Early in foetal life, the dental groove becomes closed over and subdivided by septa into follicles, within each of which a papilla arises. The follicles then change into dental sacs, and the papilla; into tooth-pulps. Within the enlarging sac, but at the expense of the pulp, the dentine forms. From the lining of the dental sac is developed (at first quite soft) the enamel organ, composed of fibres, united to the dentine of the pulp-surface. In the place of this contact, called the enamel membrane, the mineral deposition which gives the enamel hardness, occurs. Eruption of the teeth takes place when their size and hardness induce absorption of the gum by pressure. Of the milk teeth, the central incisors come through the gum at about the seventh month of infancy ; those of the lower jaw usually first. Lateral incisors, eighth to tenth month ; anterior molars, twelfth to fourteenth month ; canines (stomach and eye teeth), fourteenth to twentieth month ; posterior molars, eighteenth to thirty-sixth month. Fig. 31. \ TEETH AT FIVE YEARS. i. Temporary incisors, c. Temporary canine, m. Temporary first and second molar, and first permanent molar, i'. Permanent incisors, c'. Perma- nent canine. 6'. Permanent bicuspids, m'. Permanent second molar. Permanent teeth come out as follows : Between six and a half and seven years of age, the first molars ; seventh year, middle in- cisors ; eighth year, lateral incisors; ninth ye&r,jirst premolar; tenth year, second premolar; eleventh to twelfth year, canine; twelfth to thirteenth year, second molars; seventeenth to twenty- first year, last molars. THE ARTICULATIONS. 59 CHAPTER II. THE ARTICULATIONS. Lif/aments, cartilages, and synovial membranes constitute the apparatus of the joints between the bones. Ligaments are either of white fibrous or yellow elastic tissue. Of the latter the ligamentum nuchce and ligamenta subftava of the spine are the principal examples. Cartilages are either temporary (becoming ossified) or perma- nent. The latter are numerous in the body ; being, 1, articular cartilages ; 2, costal cartilages ; and 3, various lamellar cartilages, as those of the ear, the nose, eyelids, Eustachian tube, larynx, and other parts of the air-passages. The tissue of cartilage is, when minutely examined, found to consist of cells or corpuscles in an intercellular fibro-granular substance. It is, in mass, firm, but elastic and flexible ; either pearly white or yellow in color. Synovial membrane resembles serous membrane in structure, but secretes a peculiar fluid, synovia; which is glairy like the white of an egg. Biirsce are membranous cavities between surfaces which move upon each other; as between the patella and the skin, over the olecranon, outside of the malleoli, between the trocbanter major of the femur and the gluteal muscles, &c. Articulations are of three kinds : immovable, synarthrosis ; movable, diarthrosis ; and mixed, amphiarthrosis. Synarthroses are either sutura, with a series of interdentations ; schiitdylesis, or dove-tailing, by a thin plate of one being received into a fissure between two laminae of another ; or gomphosis, where a, conical process is fastened into a socket, as the tooth-fangs are in the alveoli. Diarthroses are of four kinds : arthrodia, which admits of glid- ing movement, as in the temporo-maxillary articulation ; enarthro- sis, or the ball and socket joint, as at the hip; ginglymus or hinge, as at the elbow ; and diarthrosis rotatorius, as between the atlas and axis vertebra, and between the upper ends of the radius and nlna. Amphiarthrosis is an articulation with but limited motion ; as, for example, that between the ossu pubis the symphysis pubis. 60 ANATOMY. VERTEBRAL ARTICULATIONS. In front of the bodies of the vertebrae, from the second cervical to the first sacral, lies the anterior vertebral ligament. It widens as it descends. Behind, upon the bodies of the vertebrae, from the occiput to the coccyx, is the posterior vertebral ligament. Between each two spinous processes is an inter-spinal ligament ; almost wanting, however, in the cervical region. Those in the dorsal region are three-sided ; the lumbar ones quadrangular. The ligamentum nuchce takes the place of the interspinal liga- ments in the back of the neck, extending from the occiput to the last cervical spine. It is strong and elastic. The Ky amenta subflava, also of elastic fibrous tissue, join the lamina? or bridges of the vertebrae, below the second cervical. Capsular ligaments surround the oblique or articulating pro- cesses; and vertical fibres, somewhat corded in the dorsal region, but scanty elsewhere, join the transverse processes. The inter vertebral fibro-cartilages, twenty-three in number, are disks, formed of concentric laminae at the circumference, and an elastic pulp at the centre; those in the lumbar region are the largest. Occiput and Atlas. The articulation here consists of an anterior and a posterior liga- ment, and a capsular ligament, including together the condyle of the occiput on each side and the oblique process of the atlas. Atlas and Axis. Across the ring of the atlas, behind the odontoid or dentate process, stretches the transverse or cruciform ligament; sending also a fasciculus up to be attached to the occiput, and one down to connect with the odontoid process. There are also two anterior atlo-axoid ligaments, one posterior atlo-axoid, and two capsular ligaments; the latter connecting the oblique processes. PELVIC LIGAMENTS. The sacrum and ilium form together a sympltysis, on each side, with a cartilage over each articular surface; and, during infancy and pregnancy, a synovial membrane partially developed. Around the symphysis are the short and strong fibres of the sacro-iliac liga- ment, sometimes divided into anterior and posterior. The sacro- spinal ligament extends from the transverse processes of the lower sacral vertebra to the posterior inferior spinous process. The iliO'lumbar ligament connects the crest of the ilium, behind, with the last lumbar transverse process. The lumbo-sacral liga- ment joins the transverse process of the last lumbar vertebra with THORACIC ARTICULATIONS. 61 the upper part of the sacrum on each side. Between the sacrum and the ischium extend the greater and lesser sacro-sciatic liga- ments. The sacro-sciatic notch is by them divided into two fora- mina for the passage of vessels and nerves, &c. The obturator ligament occupies the obturator or thyroid fora- men; it is perforated near its upper margin by vessels. The triangular sub-pubic ligament is immediately under the pubic arch. Anterior, superior and posterior ligamentous bands surround this arch. The symphysis pubis is an amphiarthrosis, with two oval articular cartilages, with an interspace lined with epithelium; this is more distinct at the time of pregnancy, when a very slight movement of the bones upon each other may be possible. TEMPORO-MAXILLARY ARTICULATION. An external and an internal lateral ligament and a capsular liga- ment constitute the periphery of this joint. The first is broad, the second forms a sheath for vessels and nerves, the third envelops the condyle of the jaw and the margin of the glenoid cavity of the temporal bone. An inter-articular cartilage and two synovial membranes are contained within the articulation. The stylo-maxillary ligament passes from the styloid process of the temporal bone to the angle of the lower jaw. THORACIC ARTICULATIONS. Ribs and Vertebrae. Around the head of each rib is a capsular ligament. Another capsular ligament joins the tubercle of the rib to the transverse process of a vertebra. The anterior radiated ligament extends from the head of the rib to the two vertebrae with which it is connected, and to their inter- vertebral cartilage. The inter- articular ligament (except with the first and two last ribs) extends from the head of the rib to the inter vertebral cartilage; a distinct synovial membrane is on each side of it. There are, further, the external, internal, and middle costo-transverse ligaments, whose names locate them. Sternum and Ribs. The anterior and posterior radiated or costo- sternal ligaments, at the anterior ends of the true ribs, pass from the cartilages of the ribs to the sternum. The anterior is most fully developed. A thin capsular ligament completes the connec- tion. The costo-xiphoid ligament joins the cartilages of the sixth and seventh ribs to the sternum. Sternum and Clavicle. A capsular ligament of considerable thick- ness surrounds the end of the clavicle and connects it with the ster- num. There is an articular cartilage between the bones. Between the sternal ends of the two clavicles passes the inter-clavicular ANATOMY. ligament. The rhomboid ligament extends from the sternal end of clavicle downwards and inwards to the cartilage of the first rib. THE SHOULDER. Fig. 32. Clavicle and Scapula. This ar- ticulation has the superior and infe- rior a cromio- clavicular ligaments, the cor aco- clavicular, which divides into the conoid and the trapezoid, and, lastly, the small coracoid liga- ment, which bridges the coracoid notch ; through the foramen thus made of this notch pass the supra- scapular nerve and artery. There is a fibro-cartilage in the scapulo- clavicular articulation. Scapula and Humerus. This is a ball-and-socket joint, with a shallow glenoid cavity; the liga- ments being powerfully supported by 0e surrounding tendons and muscles. ligaments of the shoulder ANTt SCAPULO 1. Superior acromio-clavicular liga- ment. 2. Coraco-clavicular ligament. 3. Coraco-acromial ligament. 4. Cora- coid ligament. 5. Capsular ligament of the shoulder-joint, fc Ligamentum adscititium, or coraco-humeral liga- ment. 7. Tendon of long head of the biceps muscle. , , 7 T and the coraco-humeral ligaments. The capsular ligament is pene- trated by the long tendinous head of the biceps. The coraco-humeral is sometimes called the ligamentum adscititium. The glenoid ligament is a firm marginal band surrounding the upper part of the glenoid cavity, and deepening it. The synovial membrane of this joint communicates with a bur- sal sac for the tendon of the subscapularis muscle, and sometimes with one for that of the infra-spinatus. The tendon of the biceps has its own synovial sheath, not communicating with that of the joint. The muscles related to this articulation are, the supra-spinatus, long head of the triceps, subscapidaris, infra-spinatus, teres minor, and long head of the biceps; with the deltoid more superficially. THE ELBOW. A ginglymoid articulation, chiefly between the humerus and the ulna. The radius supports it by its head, receiving a tuberosity of the humerus into a shallow cup; while the radius also rotates upon the ulna at its upper end. THE WRIST. 63 The ligaments at the elbow are, the anterior, posterior, and ex- ternal and internal lateral ligaments. The synovial membrane of the joint is an extensive one. Around the neck of the radius, suspending it Fig- 33. to the ulna, passes the orbicular or annular liga- ment, allowing of rotary motion. Between the elbow and wrist the radius and ulna are connected, nearly the whole distance, by the interosseous ligament. The round (teres) or oblique ligament (sometimes wanting) is a fibrous cord reaching downwards and outwards from the ulna at the base of the coronoid pro- cess to the radius below the insertion of the bi- ceps tendon. THE WRIST. Lower Radio-uJnar Articulation. This con- sists of an anterior and a posterior ligament, and an articular fibro-cartilage. The synovial mem- brane of this connection is called sacciform from its looseness. Pronation and supination of the forearm and hand depend upon the rotary movement of the radius upon the ulna at their lower junction. Radio-carpal or Wrist-joint. The end of the radius and the inter -articular cartilage join with the scaphoid, lunare, and cuneiform bones of the carpus. The surfaces are all covered by carti- lage. The ligaments are the anterior, posterior, and external and internal lateral. The synovial membrane is a simple one. Articulations of the Carpal Bones. These are, those of the superior row with each other, those of the second row together, and of the two rows with each other. For the first, there are two palmar, two dorsal, and two interosseous ligaments; for the second, three pal- mar, three dorsal, and two interosseous; between the two rows, an anterior or palmar, a posterior or dorsal, an external lateral, and an internal lateral. There are two distinct synovial membranes in the articulations of the carpal bones. The more extended lines the scaphoid, lunar, and cuneiform bones below, and separates them by its prolongations; covers also, and separates, the bones of the lower row ; and covers the articular ends of the metacarpal bones. The other synovial membrane lies between the cuneiform and pisi- form bones. Carpo-metacarpal Articulations. The metacarpal of the thumb INTERNAL VIEW OP THE ELBOW JOINT. 1. Capsnlar ligament. 2, 2. Internal lateral ligament. 3. Coronary ligament. 4. Ligamen- tum teres. 5. Interos- seous ligament. 6. In- ternal condyle. ANATOMY. has a capsular ligament connecting; it with the trapezium ; the joint is lined by a distinct synovial membrane. Between the metacarpal bones of the four fingers and the carpus pass the palmar, dorsal, and interosseous ligaments. Similar liga- ments, also, unite the carpal extremities of the metacarpals to each other. A transverse ligamentous band unites their digital ends underneath. ARTICULATIONS OP THE HAND. The metacarpo-phalangeal joints are ginglymoid, the round heads of the metacarpals being received into cavities of the upper ends of the first phalanges. They have an anterior and two lateral liga- ments. The inter-phalangeal articulations are, like the above, ginglymoid; and their ligaments are also one anterior and two lateral. HIP-JOINT. The strongest ball-and-socket joint in head of the femur with the acetabulum. Fig. 34. LIGAMENTS OF THE HIP-JOINT AND PELVIS. 1. Pos- terior sacro-iliac ligament. 2. Greater sacro-sciatic ligament. 3. Lesser sacro-sciatic ligament. 4. Greater sacro-sciatic notch. 5. Lesser sacro-sciatic notch. 6. Cotyloid ligament around the acetabulum. 7. Liga- mentum teres. 8. Line of attachment of the capsular ligament of the hip-joint, posteriorly. 9. Obturator ligament. the body, formed by the The ligaments are, the wtpsnlar, cotyloid, teres, ilio-femoral, and trans- verse. The capsular ligament extends from the margin of the acetabulum to the neck of the femur, sur- rounding the whole joint. It is dense and strong, especially above and in front. A synovial bursa separates it from the ilia- ens and psoas muscles. The cotyloid ligament is an almost cartilaginous ring which deepens the margin of the cavity of the acetabulum. It is thickest above and be- hind. T h e lig amentum teres or round ligament is a triangular band, whose base is attached to the bottom of the acetabu- lum, while its apex is con- nected with the head of KNEE-JOINT 65 femur, below and behind its centre. It is thus quite within the joint. The ilio-femoral ligament passes obliquely across from the ante- rior inferior spine of the ilium to the anterior inter-trochanteric line. The transverse ligament crosses the notch at the lower portion of the acetabulum, and converts it into a foramen. It is continu- ous with the cotyloid. The synovial membrane of this joint is extensive. There is also a mass of fat contained in a fossa of the acetabulum. Fig. 35. KNEE-JOINT. A hinge between the condyles of the femur and the head of the tibia, with the patella in front. Outside of the joint are the anterior ligament (ligamentum patellae); the posterior (ligamentum Winslowii); the internal late- ral; two external lateral; and the capsular ligament. Within the articulation are the two crucial ]\ga,ments (anterior external, and posterior internal) ; two semilunar cartila- ges ; the transverse and coronary ligaments ; ligamentum mucosum, and ligamenta alaria. The ligament of the patella connects the lower point of that bone with the tubercle of the tibia. It is about three inches long. A synovial bursa is between the patella and its ligament and the skin ; and a smaller one between the ligament and the tubero- sity of the tibia. The crucial ligaments are so called be- cause they cross each other, X-like. They are respectively called anterior and poste- rior, according to the place of their tibial insertion; each passing from a condyle of the femur across to the other side of the tibia. The semilunar fibro- cartilages are cres- cent-shaped, and deepen the shallow sur- faces (for the condyles) on the head of the tibia. The circumference of each is thicker than its inner concave margin. 'The transverse ligament connects the an- terior parts of the two semilunar cartilages. The coronary ligaments are numerous short fibrous bands joining the margin of the semilunar cartilages with the head of the tibia and surround- ing ligaments. 6* > ^ ^r^- , ~> THE KNEE-JOINT LAID OPEN. 1. Lower end of the femur. 2. Anterior crucial ligaruent. 3. Posterior crucial ligament. 4. Transverse fasciculus. 5. Attachment of ligamentum mucosurn. 6. Internal semi- lunar cartilage. 7. Exter- nal semilnnar cartilage. 8. Ligamentum patellae. 9, Its bursa laid open. 10. Supe- rior peroueo-tibial articula- tion. 11. Interosseous liga- ment. 66 ANATOMY. The synorial membrane of the knee is the most extensive in the body, projecting above and below the joint beneath tendons and aponeuroses. The ligamentum mncosum is a fold of it, of a trian- gular shape, under the patella. The ligamenta alaria are fringe- like folds passing on each side from the ligameutum mucosum to the sides of the patella. TIBIO-FIBULAR ARTICULATIONS. Superior Junction. This has an anterior and a posterior liga- ment, and a synovial membrane. Inferior. Of this the ligaments are, the anterior, posterior, trans- verse, and interosseous. The synovial membrane is connected with that of the ankle-joint. ANKLE-JOINT. - A perfect hinge, between the tibia and fibula above, and the astragalus below. The tibia rests upon the astragalus; the fibn- lar malleolus supports the side of the articulation. The ligaments are, the anterior, the internal lateral, and the external lateral. The anterior ligament is simple, the internal lateral is in two layers, the superficial and the deep. The external lateral has three fasciculi. The anterior and posterior of these fascicles connect the internal malleolus with the astragalus; the middle one passes from the malleolus to the os calcis. The synovial membrane of the ankle-joint invests the lining of the ligaments and goes for a short distance between the tibia and fibula.- TARSAL ARTICULATIONS. The calcaneo-astragaloid ligaments are, the external, the poste- rior, and the interosseous. The last is the principal connection between the bones. It is composed of many fibres, vertical and oblique. This articulation has two synovial membranes. Between the scaphoid, the cuboid, and the three cuneiform bones the union is maintained by the dorsal, plantar, and interosseous ligaments. The os calcis is connected with the cuboid by two dorsal liga- ments the superior and the internal calcaneo- cuboid, and by two plantar, the long and the short calcaneo-cuboid ligaments. The os rafctXand scaphoid are united by two ligaments, the superior and the inferior calcaneo-scaphoid. The astragalus forms with the scaphoid a limited ball-and-socket joint; the posterior concavity of the scaphoid receiving the round head of the astragalus. Dislocation sometimes occurs in this ar- ticulation. PIIALANGEAL ARTICULATIONS. 67 Four synovia] membranes exist in the tarsus : one, posterior cal~ caneo-astragaloid; one, anterior calcaneo-astragaloid and astragalo- Fig. 36. VERTICAL SECTION OF THE ANKLE-JOINT AND FOOT. 1. Tibia. 2. Astragalus 3. Oscal- cis. 4. Scaphoides. 5. Cuneiforme internum. 6. Metatarsal bone of the great toe. 7. First phalanx of the great toe. 8. Second phalanx of the great toe. 9. Articular cavity between the tibia and astragalus. 10. Synovial capsule between astragalus and calcis. 11. Calcaneo-astragaloid interosseous ligament. 12. Synovial capsule between astragalus and scaphoides. 13. Calcaneo-scaphoid ligament. 14. Calcaneo-cuboid ligament. 15. Syno- vial capsule between scaphoides and cuneiform internum. 16. Syuovial capsule between cuneiforme internum and first metatarsal bone. 17. Metatarso-phalangeal articulation of the great toe, with the sesamoid bones below. 18. Phalangeal articulation of the great toe. scaphoid; a third, calcaneo- cuboid ; a fourth, between the scaphoid and three cuneiform, between the cuneiform, between the cuboid and the external cuneiform, and between the middle and external cunei- form and the second and third metatarsal bones. METATARSAL AND PHALANGEAL ARTICULATIONS. Tarso-metatarsal. The three cuneiform bones and the cuboid join with the five rnetatarsals. The internal cuneiform receives that of the great toe. The second metatarsal goes against the middle cuneiform, between the internal and external ones. The third metatarsal is connected with the external cuneiform; the fourth with the same bone and also the cuboid; and thefft/i with the cuboid. Inter-articular cartilages cover the surfaces, between which there are three synovial membranes; the strength of the union being also maintained by dorsal, plantar, and interosseous ligaments. Inter -metatar sal ligaments are, the dorsal, plantar, and interos- seous. Metatarso-phalangeal. The round heads of the metatarsal bones are received into concavities of the first phalanges; the connecting ligaments are, the anterior or plantar, and two lateral. 68 ANATOMY. Plialangeal Articulations, Like those of the hand, the phalanges of each toe are united together by (at each joint) one anterior plantar, and two lateral ligaments. Synovial membranes line these articulations. CHAPTER TIT. DIGESTIVE ORGANS. Mouth. THE roof of the mouth is formed by the hard palate in front, and the soft palate behind ; its floor by the mylo-hyoid muscles. It opens posteriorly into the fauces. The mouth is lined by a mucous membrane, continuous with the lining of the pharynx, larynx, and nares, and, upon the lips, with the skin. Under the tongue is a doubling of this membrane, the frsenum linguae. A frsenum also exists within each lip at its middle, and one in front of the epiglot- tis. The lips are chiefly composed of the fibres of the orbicularis muscle, covered externally by fat and skin. The gums are formed of a dense fibrous tissue, connected with the alveolar periosteum around the necks of the teeth ; their cover- ing mucous membrane is vascular, but slightly sensitive. Papillae of capillaries and nerves are numerous upon both the lips and gums. Tongue. This, the organ of taste and, in part, of mastication, as well as of articulation, is made up principally of muscular fibres, covered by a mucous membrane supplied with papillae. The mucous membrane is much thickest on the dorsum or upper side of the tongue. It con- sists of a corium or basement membrane covered with epithelium. The papilfce of the tongue are described as maximce (circura- vallate), medice (fungiform), and minimce (conical and filiform). Of the maximce there are eight or ten, all at the posterior part of the dorsum of the tongue, arranged in a V-shape, the point behind. The medice or fungiform papillae are numerous, and scattered over the dorsum, chiefly at the sides and tip ; they are deep red in color, and rounded. The minimce, conical and filiform, cover two-thirds of the tongue anteriorly. They are minute, and are arrayed in lines nearly parallel with the rows of the maximce; only more transverse near the apex of the tongue. ^\\Q Jiliform ones have a very thick epithe- SALIVARY GLANDS. C9 lium, which gives them a Fig. 37. whitish appearance; they are also covered by secondary papillae. In structure the lingual papillae, like those of the true skin, consist essentially of ca- pillary loops, invested by ner- vous terminations, and en- veloped by epithelial cells. Over the tongue, as well as the lining membrane of the mouth, are many mucous glands and follicles. The glands abound especially upon the posterior third of the tongue. The two halves of the tongue are distinctly sepa- rated by a fibrous septum. The muscles on each side are, the hyo-glossus, genio-liyo- glossus, stylo- glossus, palato- c/Iossus, and in its substance the superior (or superficial Is], and inferior longitudinal (or lingualis} and the transverse. The arteries of the tongue are branches of the lingual t facial, and ascending pharyn- geal. Its nerves are three : the lingual branch of the fifth pair, the ttypoglossal, and the lingual branch of the glosso-pha- ryngeal. Salivary Glands. These are the parotid, submaxillary, and sublingual. The parotid, the largest, is placed just below and in front of the ear, extending from the zygoma above, to the level of the angle of the jaw below; anteriorly, it stretches a short distance over the masseter muscle; posteriorly, it reaches as far as the external meatus, and, below it, to the mastoid process. The inner surface of the parotid has two processes, one in front of the styloid process of the temporal bone, and one behind it. The external carotid artery passes through the substance of the parotid gland ; and, outside of this, also, the common trunk of the UPPER SURFACE OF THE TONGUE. a. One of the circumvallate papillae, b. One of the fun- giform papillae, d. Conical papillae, e. Glottis and epiglottis. TO ANATOMY. temporal and internal maxillary veins. The soda parotidis is a small lobe of the gland, occasionally detached from it. Fig. 38. SALIVARY GLANDS 1. Parotid gland. 2. Duct of Steno. 3. Sub-maxillary glaud. 4. Its duct. 5. Sub-lingual gland. The duct of the parotid (duct of Steno} opens inside of the cheek opposite to the second molar tooth of the upper jaw. It is about two inches and a half in length. The submaxillary gland is of considerably smaller size. It lies in a fossa of the inner face of the lower jaw-bone, near its angle. The platysma myoides muscle covers it. Its duct (of Wharton) opens under the tongue, near its frenum. The sublingual is the smallest of the three glands. It is almond shaped, and lies under the tongue, on each side, imbedded between the mucous membrane and the mylo-hyoid muscle. It has from eight to twenty ducts (ducts of Rivinus), which open at the side of the frenum ; some of them connect with the duct of the stibmaxillary. The salivary glands are all conglomerate in structure, made of lobes subdivided into lobules ; each of the latter consisting of many closed cells, connected with a common duct. Palate. The hard palate reaches from the alveoli in front of the upper jaw to the line of junction of the soft palate behind. A ridge or raphe runs along its middle line, continuous with a similar line upon the soft palate. The small palatal mucous glands are numer- ous between the mucous membrane and the bone. The soft palate (velum pendulum) is a thick flexible fold of mucous membrane, embracing muscular fibres, bloodvessels, &c. PHARYNX. 71 It is convex behind, where it is continuous with the floor of the posterior nares. At the sides it passes into the walls of the pharynx ; below, its border is free. The uvula is a conical projection, of similar structure, downward from the soft palate. On each side, from its base, pass the anterior and posterior half arches of the palate ; the anterior, to the base of the tongue, the posterior to the pharynx. The space from side to side between the opposite arches is the isthmus of t\\Q fauces. Between the two half-arches, anterior and posterior, on each side, lies the tonsil. This is a round gland of variable size, often mor- bidly enlarged. It is about opposite to the angle of the jaw. The internal carotid and ascending pharyngeal arteries pass outside of it. The tonsil has twelve or more small orifices of minute ducts or follicles. The muscles of the palate are as follows : Levator Palati ; which originates from the petrous -portion of the temporal bone, and the Eustachian tube, and is inserted into the soft palate. Tensor or Oircumflexus Palati ; arising from the spinous pro- cess of the sphenoid and the Eustachian tube. Its tendon passes around the hook of the internal pterygoid process of the sphenoid, to be inserted into the'posterior edge of the palate. Constrictor Isthmi Faucium ; originating at the middle of the soft palate, and passing along the anterior half arch to be inserted into the side of the base of the tongue. Palato-pharyngeus ; origin, soft palate; course, through the posterior half arch ; insertion, the wall of the pharynx. Its action is to approximate the palate to the pharynx. Azygos Uvulae ; arising from the posterior nasal spine, it passes through the middle of the soft palate to near the end of the uvula. Its action is to draw up and shorten the latter. Pharynx. This, opening downward from the fauces, behind the glottis, is a mucous canal surrounded by connective or cellular tissue and muscles. Below, it is continuous with the oesophagus. Above, the posterior nares and Eustachian tube are in communication with it. It lies against the spinal column, from the occiput to about the fifth vertebra. Its length is five inches in the adult ; its width is greater above than below. The epithelium of the mucous membrane of the pharynx is col- umnar and ciliated above, and squamous below. The superior constrictor muscle of the pharynx is thin and pale. It arises from the internal pterygoid process of the sphenoid and contiguous parts of the palate bone, upper jaw bone, and side of the tongue. Its insertion is described as being into the middle line of the pharynx ; some fibres, partly aponeurotic, passing up and back as far as the basilar process of the occiput. 12 ANATOMY. The middle constrictor arises from the greater and lesser cornna of the hyoid bone and the stylo-hyoid ligament. It is inserted into the median raphe of the pharynx. This muscle overlaps the superior constrictor and the stylo-pharyngeus and palato-pharyn- gens muscles. The inferior constrictor muscle is the thickest of the three. It arises from the cricoid and thyroid cartilages. Part of its fibres are horizontal, the rest ascend obliquely and overlap the the middle constrictor. The stylo-pharyngeus muscle is long and slender ; round above, broad and thin below ; arising from the styloid process of the temporal bone, to be inserted into the side of the pharynx. Its action is to draw the pharynx upwards and dilate its upper part. CEsophagus. *This canal begins where the pharynx is narrowest, opposite the fifth cervical vertebra; its length is about nine inches; its width gradually increases below. It passes through a foramen in the diaphragm, and opens by the cardiac orifice into the stomach. Outside of its mucous and cellular coats, the oesophagus has two layers of muscular fibres ; the internal circular and the external longitudinal. The circular fibres are continuous with the inferior constrictor of the pharynx. The raucous membrane of the resophagus is reddish above and pale at the lower part. Its epithelium is of the variety called squamous. Small compound glands are numerous in the sub- mucous tissue of this canal ; each has a single excretory duct. Abdomen. This important cavity is, for convenience, divided in description into nine regions. The three upper ones are the right and left hypochondriac, and, between these, the epigastric. The middle regions, the right and left lumbar, and the umbilical. The three lower ones, the right and left iliac, and the hypogastric. In the right hypochondriac region are the right lobe of the liver, the gall-bladder, duodenum, part of the arch of the colon, top of the right kidney, and right supra-renal capsule. In the epigastric region are the left half of the stomach, including the pylorus, the left lobe of the liver, and the lobulus Spigelii, the hepatic artery and vein and portal vein, the pancreas, the semilunar ganglion, and part of the aorta, as well as of the ascending vena cava, vena azygos, and thoracic duct. The left hypogastric region contains the large end of the stomach, the spleen, the left end of the pancreas, part of the colon, upper part of the left kidney, and left supra-renal capsule. The right lumbar region has the ascending colon, part of right kidney, and part of the ileum and jejunum (small intestine). ABDOMEN. The umbilical region contains the transverse part of the colon, part of the omentum majus and mesentery, part of the duodenum, and other portions of the small intestine. Fig. 39. PARIETES OF THE ABDOMEN 1, 1. Line from the highest point of one-ilium to the same point of the opposite one. 2, 2. Line from the anterior superior spinous process to the cartilages of the ribs. 3, 3. A similar one for the opposite side. 4, 4. Line drawn perpen- dicularly to these. 5, 5. Right and left hypochondriac regions. 6. Epigastric region. 7. Umbilical region. 8, 8. Right and left lumbar regions. 9. Hypogastric region. 10, 10. Right and left iliac regions. 11. Lower part of the hypogastric, sometimes called pubic. In the left lumbar region are the descending colon, lower part of left kidney, and part of the small intestine. In the right iliac region lie the caecum or caput coli, with the vermiform appendix, the ureter, and the spermatic vessels. In the hypogastric region are portions of the small intestine, the bladder in the child, or in the adult when it is distended, and the uterus in the pregnant female. The left iliac region holds the sigmoid flexure of the colon, the left ureter, and spermatic 7 ANATOMY, Fig. 40. Peritoneum. This is the most extensive serous sac in the body; thin, trans- parent, and moistened with serum like other serous membranes. It is duplicated over all the viscera of the abdomen and the inner wall of the cavity itself; while certain folds of it act the part of ligaments to fix or suspend the visce- ra. Omentum is the name applied to the intermediate double folds of the perito- neum. The omentum minus con- nects the stomach and the liver ; omentum majus pass- es from the stomach to the colon ; the meso-colon fixes the colon to the vertebral column ; the mesentery con- nects the folds of the small intestine with the abdomi- nal walls. The gastro-colic or greater omentum hangs over the intestines, apron - like ; it is sometimes named the caul. The reflections of the pe- ritoneum may be succes- sively traced as follows, beginning at the umbilicus: upward, within the wall of the abdomen, to the dia- phragm ^backwards under that ; forwards over the liver, and back under it most of its width; then forward over the stomach, and down, apron- like (part of omentum majus) in front of the colon, to ascend again to its under surface, pass under it and back to the spine ; thence obliquely forward and downward around the small intestine, and returning to the spinal column (mesentery), to descend in front of the rectum to near the lower posterior part of the bladder ; for- ward and upward over the upper surface of the bladder, and thence upward within the abdominal wall to the starting point at the umbilicus. The foramen of Winslow is a communication between the cavity THE PERITONEUM. D. Diaphragm. L Liver. S. Stomach. C. Transverse colon. D. Transverse duodenum. P. Pancreas. I. Small intestines. R. Rectum. B. Bladder. STOMACH. of the greater amentum and the general peritoneal cavity, where the gastric and hepatic arteries pass forward, from the arterial trunk called the caBliac axis, to the stomach and liver. This fora- men is bounded above by the lobulus Spigelii, in front by the lesser omentum, behind by the ascending vena cava, and below by the hepatic artery. In the female, the peritoneal reflections deviate from the lower part in front of the rectum, going thence upwards over a small part of the vagina over the body of the uterus, from the sides of which it extends in the form of the broad ligaments to the pelvic walls, and then descending in front of the uterus to the bladder ; thence upwards and forwards as in the male, it covers the upper part of the bladder and ascends within the abdominal wall. The lower part of the rectum, the neck, base, and front of the bladder, and the lower part of the vagina, have no covering of peritoneum. It is deficient also at the ends of the Fallopian tubes in the female. The appendices epiploicce are pouches of the peritoneum holding masses of fat, along the colon and rectum, especially connected with the transverse colon. Stomach. The stomach is placed next within the front wall of the abdo- men, below the diaphragm and liver; chiefly in the left hypochon- driac and epigastric regions. It is irregularly rounded, the left end much the largest. When full, it is about twelve inches in transverse diameter, and four vertically, in the adult. The left end of the stomauh is sometimes called the splenic end, being connected by omentum with the spleen. The right end is the pyloric portion, it touches the lower surface of the liver. The oesophagus empties into the cardiac orifice, which is nearest the large end, in the upper portion of the stomach. The pylorus is the valvular opening from the stomach into the duodenum. Between the cardiac and pyloric orifices, on the upper surface, is the lesser curvature of the stomach. The greater curvature is between the same points around the lower surface. Four coats of the stomach are described : the serous, muscular, cellular, and mucous coats. The serous coat is an extension of the peritoneum over almost the whole organ. The muscular coat consists of three layers of fibres: longitudinal, circular, and oblique. The first are most superficial ; the second are next within them over the whole stomach, but most developed at the pylorus, where they make a ring-like valve. The oblique fibres are most abundant about the cardiac orifice. 76 ANATOMY. Fig- 41. The cettularcozt is form- ed of loose connective tis- sue, containing the blood- vessels. The mucous coat is thick, soft, and velvety; pink in color in the young, pale yellow or gray in the adult. Under the microscope it ex- hibits a honeycomb struc- ture, being covered with depressions from T o tn to 3 Jnum. 3. Lower lip. 4. Frsenum. 5. Chock. 6. DuctofSteuo. 7. Roof of mouth. 8. Half arches. 9. Tonsils. 10. Velum pendulum. 11. Tongue. 12. Papillae. 13. Trachea. 14. (Esophagus. 15. Its interior. 16. Stomach. 17. Its greater end. 18. Its lesser end. 19. Lesser curvature. 20. Greater curvature. 21. Cardiac orifice. 22. Pylorus. 23, 24, 25. Duodenum. 26. Valvulae conniventes. 27. Gall- bladder. 28. Cystic duct. 29. Hepatic ducts. 31. Ductus communis choledochus. 32. Its opening. 33. Jejunum. 36. Ileum. 37. V. couniventes. 38. Ilium. 39. Ileo-colic valve. 40, 41. Caecum. 42. Appendix vermiformis. 43-48. Colon. 49, 50. Rectum. 51. Levator ani muscle. 52. Anus. The nerves of the stomach are branches of the right and left pneumogastric, and of the ganglionic or sympathetic. MUCOUS MEMBRANE OF SMALL INTESTINE. 77 Intestines. The small and large intestine together have a length of between thirty and thirty-five feet in all ; of which about twenty feet belong to the upper or small intestine. The small intestine is divided in description into the duodenum, jejunum,, and ileum. All of these have a serous, muscular, cellular, and mucous coat. The serous coat is a mesenteric extension. The muscular coat has longitudinal and circular fibres. The cel- lular coat is merely connective. The mucous coat has some peculiarities in the different parts. Duodenum. This is named from its length, which is the breadth of twelve fingers or nine or ten inches^ It is curved in position, horseshoe like, first ascending, then descending, and then its longest portion going transversely to end in the jejunum. It is in contact, at different parts, with the liver, gall-bladder, pancreas, colon, dia- phragm, aorta, and vena cava. The interior of the duodenum is usually stained with bile. Jejunum. This makes two-fifths of the small intestine below the duodenum. It has a somewhat greater diameter than the ileum, with thicker walls and more vascularity and color. There is no boundary whatever between the two the names being somewhat arbitrary. Ileum. Three-fifths of the small intestine, almost, have this name. The ileum ends in the ileo-ccecal valve, which is between it and the caecum, in the right iliac fossa. Mucous Membrane of Small Intestine. This is covered by columnar epithelium. To the unaided eye it presents numerous transverse foldings, called valvular connivent.es. The depth of these is sometimes two-thirds of an inch, usually less. They first appear an inch or two from the pylorus. Large in the duodenum and upper part of the jejunum, they afterwards diminish, and are almost entirely absent in the lower part of the ileum. Their use is to retard the passage of food during diges- tion and absorption. Villi are minute projections from the intestinal mucous mem- brane, either conical, pyramidal, or cylindrical in shape. From forty to ninety of them have been counted upon the square of a line ( T ! 2 of an inch). Each villas contains a minute network of capillaries and lacteal tubes inclosed in basement membrane, on 7* 78 ANATOMY. which is a single layer of columnar epithelial cells, perpendicular to the surface. The length of the villi varies from ^ to -g of an inch. The follicles or crypts of Lieberkiihn are scattered over the lining of the whole of the small intestine. Each is a tubular depression of the mucous membrane, ^orr of an inch in diameter, having a circular outlet. The glands of Brunner are found only in the duodenum and upper part of the jejunum. They are small, flat, and granular in appearance, with minute ducts most abundant near the pylorus. Fig. 42. VlPCERA, AFTER REMOVAL OF THK FAT IN THE ClIKST AND THE O.MENTUM MAJU8 OF THE AB- DOMEN. THE LIVER ALSO TURNED BACK 1. Great bloodvessels of tlie licart. 2. Luugs of each side. 3. Heart. 4. Diaphi-agm. 5. Liver. 6. Gall-bladder. 7. Ductus choledocbus. 8. Stomach. 9. The gastro-hepatic, or lesser omentum. 10. Gastro-colic, or greater omentum, cut off. 11. Transverse colon. 12. Its ascending portion. 13. Small intestines. 14. Signioid flexure. 15. Appendix vermiformis. MUCOUS MEMBRANE OP LARGE INTESTINE. 79 The solitary glands are met with in all parts of the small intes- tine, especially in the lower part of the ileum. They are round and whitish, about ^ of an inch in diameter. Each is a closed sac, with no duct, although around each is a circle of orifices like those of the Lieberkiihnian follicles. Peyer's glands (glandulae agminatae) are round or oval patches of glands like the solitary glands. The patches vary in length from half an inch to four inches. Large Intestine. This comprises the cczcum, colon, and rectum. Its whole length is about five feet. Its diameter is considerably greater than that of the small intestine, and it is more fixed in position. Its division, in description, into three parts is arbitrary, but convenient. Caecum. The caecum or caput coli begins at the ileo-caecal valve in the right iliac fossa. It has a diameter of about 2 inches. The vermiform appendix is attached to this part of the bowel. It is about as thick as a goose-quill, and from three to six inches long ; it opens into the caecum by an incomplete valve. The ileo-ccecal valve (valve of Bauhin) is formed of two folds of mucous membrane of semilunar shape, so disposed that disten- sion of the caecum forces the margins of the folds together, and closes the valve. Colon. The colon has an ascending, a transverse, and a descending portion (arch of the colon), and a sigmoid flexure. The diameter of the colon is less than that of the caBcum. The sigmoid flexure (named from the letter S) ends in the rectum, opposite to the left sacro-iliac symphysis. Rectum. The terminal and nearly, though not quite, straight part of the intestine is thus named. It is six or eight inches in length. Its size increases as it descends to the anus, its outlet, which is provided with a sphincter muscle. Mucous Membrane of Large Intestine. This coat is smooth, not villous, but laid in crescentic folds. It is gray or pale yellow in color, darker in the rectum ; where also it is thicker and more vascular. Its epithelium is columnar. Near the lower part of the rectum there are from two to four semilunar pouches, half an inch in width. Simple follicles, or tubular depressions, are more numerous in 80 ANATOMY. the large than in the small in- testine. They have minute round openings. Solitary glands also are abun- dant, especially in the caecum and appendix. They are small, flask-shaped, whitish, and with a very small central outlet. Liver. This is the largest gland in the body. It chiefly occupies the right hypochondriac re- gion, immediately under the diaphragm, reaching over, how- ever, through the epigastric into the left hypochondriac. Its transverse diameter is from ten to twelve inches; antero- posterior, six to seven inches. Its greatest vertical thickness, three inches ; weight, from three to upwards of four pounds. The liver is convex on its upper surface, and concave be- low ; posterior border round and wide, anterior border thin and sharp, with a deep notch. This border nearly corresponds with the margin of the ribs. The right half of the liver is much the thickest. It is divided by a fissure and by the broad or suspensory ligament (peritoneal) into the right and left lobes. The right lobe is much the largest; it is quadrilateral in shape. On the under surface of this lobe are three fissures : the transverse fissure, that for the gall- bladder, and for the vena cava. The colon, right kidney and supra- renal capsule are in contact with it. The left lobe is convex above, concave over the stomach below. Behind, it reaches nearly to the cardiac orilice of the stomach. Beneath the right lobe is a portion of the liver called the lobulus quadratics, or square lobe. The lobulus Spigelii projects from the back part of the under surface of the right lobe. The lobulus caudatus extends obliquely outwards from the base of the lobulus Spigelii to the under part of the right lobe. The liver then has, as just described, jfa;e lobes ; it also has five ligaments and five fissures. The ligaments are, all but one, folds of peritoneum. They are called, respectively, the longitudinal (broad, suspensory), two lateral, coronal, and round ligaments. THE LARQB INTESTINE. 1. End of theileum. 2. Appendix vermiformis. 3. Cfecum, or ca- put coli. 4. Transverse colon. 5. Descending colon. 6. Sigmoid flexure. 7. Commence- ment of rectum. 8,8. The rectum. 9. Anus. LIVER. 81 The longitudinal or broad ligament is principally attached above to the diaphragm ; in front, to the sheath of the rectus abdominis muscle. The lateral ligaments are triangular, and are attached to the diaphragm. The coronary ligament connects the posterior border of the liver with the diaphragm. The round ligament (teres), is a fibrous cord, the remainder of what was the umbilical vein. It may be traced from the navel to the anterior notch of the liver, and along the longitudinal fissure underneath it, as far as to the vena cava. The fissures of the liver are, the longitudinal, that of the ductus venosus (of the foetus), the transverse, that of the gall-bladder, and that for the vena cava. The vessels of the liver are, the hepatic artery, portal vein, hepatic vein, hepatic duct, and the lymphatics. The capsule of Glisson is a coat of loose connective tissue which envelops the vessels of the liver and accompanies them for some distance through the organ. The liver is supplied with nerves from the hepatic plexus of the ganglionic or sympathetic, from the pneumogastrics, and from the right phrenic. Structure of the Liver. Its substance (seen to be granular, when torn, by the naked eye) is made up of a great number of minute lobules, each called an acinus. The whole liver is penetrated by the vessels already named, and is covered by a fibrous and a serous or peritoneal coat. Each acinus is about T ^ to -^ of an inch in diameter. Its shape, transversely, is polygonal. It is suspended, as it were, by its capillaries, from a branch of the hepatic vein ; it is interpene- trated by a plexus of capillaries from the portal vein and hepatic artery, and surrounded by a plexus of biliary tubuli or ducts ; the mass of each acinus being formed of cells. These cells have a diameter, each, of i^V^ to ^oW f an i ncn - They are nucleated, sometimes with two nuclei. They contain yel- low biliary matter, which they secrete from the blood. The origin of the bile-ducts is yet undetermined. Kolliker con- siders them to commence in a network outside of the acini. Kiernan and Leidy believe them to ramify through and within each acinus, its cells being held in their meshes, as well as in those of the capillaries. All of the biliary ducts conjoin to form two, one for the right and one for the left lobe, which issue at the transverse fissure, and, uniting, make the hepatic duct. This, after an inch and a half, about, of length, joins at an acute angle the cystic duct (of the gall- bladder), thus constituting the ductus communis choledochus, or common biliary duct, which empties into the duodenum. This ductus communis is three inches long, and about as large as a goose- quill. It passes close to, and sometimes through the pancreas. 82 ANATOMY. Gall-Bladder. This reservoir for bile lies under the liver. It is pear-shaped ; having an anterior rounded fundus, and a posterior narrow neck or stem. It is about four inches long by one inch broad ; and holds eight or ten fluidrachms. It has three coats : serous, fibro-muscular, and mucous. The serous or peritoneal coat covers only its under surface. Spleen. A ductless gland, in the left hypochondriac region (opposite the ninth, tenth, and eleventh ribs); oblong, flattened and rounded, about five inches long, three or four inches wide, and an inch and a half in thickness; in color, dark bluish-red. It is covered "by the peritoneum, and connected with the stomach by omentura. A suspensory ligament joins it above to the diaphragm. A verti- cal fissure called the hilus, divides its inner surface. Within the serous or peritoneal coat is the elastic Jibrous coat of the spleen. This coat, besides embracing the whole organ, is, at the hilus, extended inwards over the vessels. From the sheaths so formed, and from the rest of the coat, many bands (trabeculoc) pass in every direction ; by their interunion the peculiar areolar structure of the spleen is constituted. By the presence of this tissue a great degree of elasticity is conferred upon the spleen, admitting of great variations of size. It is sometimes remarkably enlarged in ague. In the interspaces of the trabeculae is the proper substance of the spleen, which is soft and pulpy, and of a dark reddish-brown color. The Malpighian corpuscles are spherical, gelatinous, whitish, semi-transparent bodies, ^ to ^ of an inch in diameter, scattered through the substance of the spleen. They are most distinct in the young subject. They are attached to the sheaths of the smaller arteries, "like moss-rose-buds." Each consists of a capsule formed from the substance of the vessel-sheaths, and containing a soft white pulpy substance, consisting of granules, cells, and nuclei. On the surface of each Malpighian body are ramifications of the arteries, of veins, and a capillary network. The splenic artery, and the splenic veins, are very large for the size of the organ. The splenic artery is also tortuous. The spleen has lymphatic vessels, some of which are deep- seated, and others superficial. Pancreas. An oblong, flattened, hammer-shaped conglomerate gland, the head being at its right end, embraced by the duodenum ; the left end or tail reaching to the spleen and left kidney. Its length is six or eight inches ; breadth an inch and a half; thickness half an inch to an inch. LARYNX. 83 The posterior surface of the pancreas is separated from the first lumbar vertebra by the superior mesenteric vessels, vena cava, vena portae, aorta, left kidney, supra-renal capsule, and vessels. The duct of the pancreas (ductus Wirsungii) passes from left to right to open into the duodenum near its middle, by an orifice generally common to it and the ductus communis choledochus. The pancreatic duct is of the size of a goose-quill ; it is occasion- ally double. In structure, the pancreas closely resembles the salivary glands. It is supplied with arteries, veins, lymphatics, and nerves. CHAPTER IV. OKGANS OF RESPIRATION. THE windpipe is composed of the larynx, trachea, and bronchial tube, with its branches, communicating with the lungs. Larynx. This is the special organ of voice. It lies just below the root of the tongue, in front of the pharynx and under the skin. It is chiefly composed of carti- lages, with a mucous membrane, liga- ments, and muscles. In shape, it is triangular above, having a prominent vertical ridge ; and cylindrical below. Nine cartilages enter into the larynx : the thyroid, cricoid, epiglottis, two arytenoid, two cornicular, and two cuneiform. The thyroid cartilage is the largest. It consists of two flat sides or wirrgs, meeting in front in the ridge called pomum Adami or Adam's apple. This ridge is most strongly marked in the male. It is surmounted by a deep notch. Within, the surface of this car- tilage is lined with mucous membrane, to which the chordae vocales are attached. The lower border of the thyroid car- tilage is connected to the cricoid, by a membrane in front, and by muscles at the sides. Fig. 44. THE LARYNX. 1. Os hyoides. 2. Thyreo-hyoid ligament. 3. Coma majus of thyroid cartilage. 4. Its angle and side. 5. Cornu minus. 6. Lateral portion of cricoid cartilage. 7. Kings of trachea. 84 ANATOMY. The posterior border ends above in the superior cornu, on each side, which is long and narrow. Below, the same border ends in the inferior cornu on each side ; which is short and thick. The cricoid cartilage is ring-like in shape, smaller but thicker than the thyroid, and situated below and behind it. It may be described as composed of two halves, anterior and posterior. On each side, at the junction of the two halves, there is a small elevation, to which is attached the lower cornu of the thyroid cartilage. The under border of the cricoid is connected by membrane with the first ring of the trachea. Its upper border slopes upwards and backwards between the wings of the thyroid. At the highest point, on each side, it sup- ports on an oval surface the arytenoid cartilage. The cricoid cartilage is lined by mucous membrane continuous with that of the thyroid. The arytenoid cartilages are small and pyramidal ; they rest upon the cricoid at the back of the larynx, one on each side. The apex of each is curved backwards and inwards, and sur- mounted by the small conical cornicular cartilage (cartilage of Santorini). The cuneiform cartilages (of Wrisberg) are just in front of the arytenoid ; they are quite small, of elongated shape, lodged in the mucous membrane between the arytenoid cartilages and the side of the epiglottis. The epiglottis is the lid of the upper aperture of the larynx called the glottis, which is considered to extend to the inferior vocal chords. The rima glottidis is the fissure between those chords. The epiglottis is a thin fibro-cartilage, attached to the upper front border of the thyroid by a narrow neck, and having a brond and round free margin, which is vertical during respiration, but closed backwards over the glottis in swallowing. The external ligaments of the larynx are as follows : Connecting the thyroid cartilage with the hyoid bone, three the thyro-hyoid membrane and two lateral thyro-hyoid ligaments. Between the thyroid and cricoid cartilages, three the crico- thyroid membrane and two capsular ligaments, each with a synovial membrane. The latter join the cricoid to the lower cornua of the thyroid. The cricoid and arytenoid cartilages are connected by strong posterior crico-arytenoid ligaments and thin and loose capsular ligaments. The ligaments of the epiglottis are the nyo-epi glottic and tJiyro- epiglottic ligaments. It is connected also with the base and sides of the tongue by three folds of mucous membrane. LARYNX. 85 VIEW OP THE LARYNX -PROM ABOVE. 1. Superior edge of the larynx. 2. Its anterior face. 3. Cornua majores of thy- roid cartilage. 4. Posterior face of cricoid cartilage. 5, 5 Arytenoid cartilages. 6, 6. Thyreo-arytenoid ligaments. 7. Their origin. 8. Their terminations. 9. Glottis. 10. Cricoid cartilage. The superior aperture of the larynx is almost cordiform, widest in front. The laryngeal cavity ex- tends from the epiglottis to the lower edge of the cricoid cartilage. The vocal chords and their con- nections divide it into two parts. The chords are called inferior and superior, or true and false vocal chords. The latter are formed of mucous membrane only ; in the inferior or true vocal chords are ligamentous fibres also. The orifice of the glottis varies in shape and size during vocalization and res- piration. The ventricle of the larynx (of Galen) is a cavity on each side, between the superior and inferior vocal chords. The sacculus or pouch of the larynx (sinus of Morgagni) is a small conical sac in front of and higher than the ventricle, com- municating with it by a narrow opening. It yields a secretion which lubricates the vocal chords. The muscles of the larynx are, the crico-thyroideus, crico-arytce- noideus lateralis, crico-arytcenoideus posticus, arytcenoideus trans- versus, and thyro-arytcenoideus. The crico-thyroid muscle, on each side, passes upwards and out- wards from the front and side of the cricoid cartilage, to the lower and inner border of the thyroid. The action of these muscles is, by drawing the thyroid cartilage down, to elongate and make tense the vocal chords. The crico-arytcenoideus posticus passes from the posterior part of the cricoid cartilage, on each side, to the base of the arytenoid. Its action is, by drawing the arytenoid cartilages outwards and backwards, to open the glottis, making the chords tense at the same time. The crico-arytanoideus lateralis, on each side, arises near the front of the upper border of the cricoid, and passes upwards and backwards to be inserted into the base of the arytenoid. The action of the lateralis is, by rotating the arytenoid cartilages, to approximate their anterior faces, and thus narrow the orifice between the vocal chords. The arytcenoideus transversus is a single muscle, crossing upon the back of the two arytenoid cartilages, from one to the other. Some of its fibres are oblique. Its action is to draw the two carti- lages together, and thus to narrow the glottis. 8 86 ANATOMY. The thyro-arytcenoidem is a broad, flat muscle, within the larynx on each side, lying parallel with the inferior vocal chord, passing from the thyroid back to the front surface of the base of the aryte- noid. Its action is to draw the arytenoid forward towards the thyroid, thus relaxing the vocal chords. The thyro-epiglottidei muscles depress the epiglottis. The ary- tceno-epiglottideus superior constricts the rima glottidis when the epiglottis closes over it for deglutition. The arytano^yglottideus inferior compresses the sacculus laryngis. Trachea. Continuous with the larynx, below it, is this tube, four or five inches in length, to the level of the third dorsal vertebra; there it branches into the right and left bronchi. The trachea is composed of eighteen or twenty imperfect rings of cartilage, completed in the posterior third of each by muscular fibres, and united by fibrous and elastic ligaments. The muscular fibres are both longitudinal and transverse ; the former most external. They are unstriped and involuntary. The trachea and bronchi are lined by mucous mem- brane. The black bronchial glands are lymphatic glands, situated at the bronchial bifurcation. The right bro?ichus is shorter and larger in calibre than the left. Both ramify into a multitude of branches or ramules, terminating finally in the lungs, in direct communication with the air-vesicles. Fine muscular fibres are discovered by the microscope even in the smaller ramules. Thyroid Gland. This is a ductless gland, formed of two lobes, one on each side of the trachea, with an isthmus connecting them, across the second and third tracheal rings. Its weight is one or two ounces ; color, brownish-red. It is largest in females ; increasing a little during menstruation. It is much enlarged in goitre or bronchocele. The right lobe is somewhat larger than the left. In structure, this gland is composed of minute closed vesicles invested by a dense capillary network, combined into lobules by connective tissue. The vesicles are almost spherical, and contain a yellowish fluid. Thymus Gland. This, too, is a ductless gland. It attains its full size at two years of age; it is then gradually absorbed, and almost ceases to exist at the time of puberty. It is situated in the lower part of the neck and the anterior mediastinum, behind the sternum. It consists of two unequal lobes united together, with sometimes an intermediate lobe. Its color is pinkish -gray. At its full develop- LUNGS. 8t ment, it is about two inches long, one and a half wide, and a quarter of an inch in thickness. In structure, the lobes of the thyraus are composed of numerous lobules, with a common dense capsule. Each lobule (varying in size from that of a pin's head to that of a pea) contains a number of smaller lobules, around a central cavity. These lesser or secondary lobules are also hollow. The latter communicate with the cavities of the primary lobules, and these open into a great central cavity, the reservoir of the thymus, which extends through the length of each lateral lobe of the gland. A white milky fluid is found in this reservoir. In its development, the thymus has been shown to begin as a linear tube, with diverticula from it. Lungs. Each lung is conical ; with the apex above, and a concave base, lower behind than in front. The right lung is largest, being broader and shorter than the left; it has three lobes, the left but two. The fissure is posterior and deep, between the two lobes of the left lung, and between the upper and lower of the right ; a shorter fissure separates the middle triangular lobe from the upper one of the right lung. The root of the lungs is the place of their connection with the windpipe and the heart, by the bronchi and the bloodvessels, nerves, &c. Most anterior are the pulmonary veins; next the pul- monary artery ; behind, the bronchus, for each lung. From above downwards, on the right side, the succession is, bronchus upper- most, then pulmonary artery, lowest pulmonary veins ; on the left side, pulmonary artery, bronchus, pulmonary veins. The lungs together weigh about 42 ounces; less in the female. Their color is pinkish white at birth, mottled with slate-colored patches in the adult, the patches growing black with age: The lung-substance is light, spongy, and elastic, crepitating under pressure, and floating in water. When removed from the chest the lungs collapse. Each lung has a serous coat, a part of the pleura, an elastic are- olar or connective tissue, and the parenchyma or proper substance of the lung. The parenchyma is formed of lobules, most easily separable in the foetus. They vary in size and form. Each consists of the terminal ramifications of a bronchial branch, with their air-cells, and the attendant bloodvessels, lymphatics, and nerves ; all united by fibrous connective tissue. The bronchial ramules are formed of many cartilaginous pieces, with a mucous membrane lined with ciliated columnar epithelium. When the size of these ramules becomes reduced almost to th 88 ANATOMY. of an inch, they become irregular, losing their cylindrical form, and opening in every direction into the air-cells. Fig. 46. BRONCHI AND BLOODVESSELS. 1. Left auricle. 2. Right auricle. 3. Left ventricle. 4 Right ventricle. 5. Pulmonary artery. 6. Arch of the aorta. 7. Superior vena cava. 8. Arteria innominata. 9. Left primitive carotid artery. 10. Left subclavian artery. 11. Trachea. 12. Larynx. 13. Upper lobe of right lung. 14. Upper lobe of left lung. 15. Trunk of right pulmonary artery. 16. Lower lobes of the lungs. The air-cells are many-sided, divided from each other by their walls or septa of a diameter from 7 ^th to ^^th of an inch. They, as well as the last bronchial intercellular passages, are lined by a thin mucous membrane, with a squamous epithelium. The number of these air-cells in an adult is estimated to be several hundred millions. By the pulmonary artery and its branches, all the venous blood of the body is carried from the heart to the lungs, where it is dis- tributed minutely amongst the air-cells by finely-divided meshes of capillaries with thin walls. From their network arise the pul- monary veins, which return the blood to the heart. The bronchial arteries furnish blood to the lungs for their nutri- URINARY AND GENITAL ORGANS. 89 tion. Some of their branches and capillaries terminate in the bronchial, and others in the pulmonary veins. The nerves of the lungs are supplied chiefly from the pneumo- gastric and sympathetic or ganglionic. The lungs have also super- ficial and deep lymphatics. Pleurae. These are the serous coverings of the lungs, reflected, from their roots, over the inner walls of the thorax. The portion over the lung is the pleura pulmonalis, and that over the ribs, pleura costa- lis. Between the two is the cavity of the pleura. Like the other serous membranes, the pleura is thus a closed sac or double mem- brane. The pleura rises, over the apex of each lung, about an inch above the first rib, through the upper orifice of the thorax. Below, it covers the diaphragm. The anterior mediastinum is the interspace between the two pleura3 in front, above and below their point of contact behind the sternum, just above its middle. This cavity is limited behind by the pericardium. The middle mediastinum is a broader inter- pi eural cavity, con- taining the heart, in its pericardial sac, the ascending aorta, descending vena cava, bifurcation of the trachea, pulmonary arteries and veins, and phrenic nerves. The posterior mediastinum is a triangular space, in front of the spinal column, bounded in front by the pericardium and roots of the lungs, and at the sides by the two pleurae. CHAPTER Y. UR1NAHY AND GENITAL ORGANS. Kidneys. EACH kidney is situated in the lumbar region, from the level of the eleventh rib to near the crest of the ilium; the right one being a little the lowest. It is surmounted by the supra-renal capsule, and surrounded by fat. Its position is maintained chiefly by its bloodvessels. The kidney is somewhat convex in front, and flattened poste- riorly ; convex on its external border, and concave on the internal margin ; the upper end thicker and rounder than the lower. The right kidney is in contact in front with the liver, duodenum, 8* 90 ANATOMY. and ascending colon ; the left kidney, with the stomach, spleen, pancreas, and descending colon. The hilus of the kidney is a deep notch in its internal border, where the vessels pass in and out. The pelvis of the kidney is the concavity within it. Each kidney is about four inches long by two in width and one in thickness, in the adult; weight, 4-J to 6 ounces, half an ounce less in the female. The left kidney is longest, thinnest, and lightest by about 2 drachms. A fibrous capsule surrounds the kidney, and enters at the hilus to invest the bloodvessels and beginnings of the excretory duct. The general color of the kidney substance is deep red. It is firm on pressure, but easily torn ; and is divisible into the cortical or external, and the medullary substance. The cortical substance forms an external layer of about Jth of an inch in thickness, with prolongations inwards. Scattered numer- ously through it are the small red Malpighian bodies ; around these are small granular cells, convoluted tubuli uriniferi (tubes of Fer- reijt}, bloodvessels, lymphatics, and nerves. The Malpighian bodies have a diameter of about T l T th of an inch. Each is a capillary tuft, inclosed in a membranous capsule, the beginning of one of the uriniferous tubules. The tufts are the networks of small arteries (vasa ajferentia}', and from them and the capillary plexus outside of them, go minute veins (vasa efferentia), which also form plexuses around the tubuli uriniferi. The medullary substance is formed of pale red cones (pyramids of Malpighi) about fifteen in number, with their apices (papillae of the kidney) projecting into the central cavity of the gland. Each papilla has about a thousand orifices of tubuli uriniferi. The pyramid of Malpighi is composed of many lesser cones or pyramids (pyramids of Ferrein), which are themselves made up of straight tubes (of Bellini}, the continuations of the convoluted tubuli of the cortical substance. Over each papilla is an infundilulum, or small membranous cup; four or five infundibula together make a calyx; and all the calyces, from seven to thirteen in number, open into the pelvis of the kid- ney ; from which proceeds the ureter or excretory duct. The ureter is a tube of the diameter of a goose-quill ; it has a fibrous, a muscular, and a mucous coat. It passes obliquely in- wards and downwards for the length of sixteen or eighteen inches, behind the peritoneum, to enter the base of the bladder. The entrances of the two ureters are about two inches apart. The renal artery, which supplies the kidney, is a large vessel in proportion to the size of the gland. As it enters the hilus it divides into four or five branches. The renal vein empties into the vena cava. The kidney has superficial and deep lymphatic vessels. SUPRA-RENAL CAPSULES BLADDER. 91 Supra-Renal Capsules. These are small, flat, yellowish bodies, behind the peritoneum, one in front of the upper end of each kidney, classed with the " ductless glands." They vary in size in different individuals, but the left is usually the largest average length, an inch and a half; width, an inch and a quarter; thickness, one-fifth of an inch. In structure the capsule has an external cortical, and an internal medullary substance. The former is most extensive ; and is formed of narrow columns perpendicular to the surface. The medullary substance is soft, pulpy, and brown in color. Microscopical anatomists differ in their view of the minute character of the columnar masses. The medullary substance is composed of nuclei and granules, amidst which is a plexus of very small veins. Nerves abound in the supra-renal capsules ; derived from the ganglionic or sympathetic plexuses, and the pneumogastric ; one observer says also the phrenic. These nerves have a number of small ganglia upon the surface of the capsules. Bladder. Situated behind the pubes, in front of the rectum in the male, and of the uterus and vagina in the female, the bladder rises higher in the infant than in the adult. In the adult, when empty, its sum- mit reaches to the upper line of the symphysis pubis ; when filled it rises, in a round form, into the hypogastric region, to a greater or less distance above the bony rim of the pelvis according to its distension. Its vertical diameter is the greatest in the male ; the transverse in the female ; and its capacity is greatest in the latter. When moderately full, the male adult bladder measures about five inches by three ; and contains a pint. The summit of the bladder is connected with the umbilicus by the urachus, a fibrous and partly muscular cord, having on each side of it the remnants of the hypogastric arteries, as round fibrous cords. The urachus, in the embryo, is a tube, by which the blad- der communicates with the membranous extra-abdominal sac called the allantois. The body of the bladder is only covered with peritoneum on its posterior surface. The vas deferens runs in a curve, from before backwards, along the side of the bladder towards its base. The base or fundus of the bladder is directed downwards and backwards. Its dimensions vary with the fulness of the organ. The neck or cervix of the bladder is the narrow part connected with the urethra. It is, in the male, surrounded by the prostate gland. The lic/aments of the bladder are called true and false; five of 92 ANATOMY. the former and five of the latter. The true are, the two anterior, going to the pubes ; two lateral, which are broader, and are formed of the fascia between the bladder and rectum ; and the urachus. The false ligaments are, the two posterior, two lateral, and one superior. The posterior pass in the male to the sides of the rec- tum ; in the female, to the side of the uterus. The lateral are folds of peritoneum from the iliac fossa3. The superior ligament is a fold of peritoneum from the summit of the bladder to the umbili- cus. The bladder has a partial serous, a muscular, a cellular, and a mucous coat. The muscular coat consists of two layers of unstriped muscular fibre ; longitudinal without, and circular within. The former are most abundant on the front and back surfaces ; the latter, around the neck. There they form the sphincter vesicce, continuous with the muscular fibres surrounding the prostate gland. Some oblique fibres also go from the prostate to the ureters. The mucous coat is smooth and pale-red. It is most closely united to the muscular coat at the neck. It has a number of small cluster-like (racemose) glands, about the neck, and a few scattered mucous follicles. Its epithelium is intermediate between the squamous and the columnar form. The vesical triangle (trigonuni) is just beneath the opening of the urethra from the neck of the bladder ; its apex is forwards. It is bounded in front by the prostate gland, and at the sides by the vasa deferentia and vesicula? seminales. The uvula vesicse is a small elevation of the mucous membrane, or thickening of the prostate, projecting into the orifice of the urethra. Urethra. In the male, when the penis is relaxed, this tube has the shape of the italic S. Its length is eight or nine inches. It is described as having three parts the prostatic, membranous, and spongy portion. The prostatic is the widest, is spindle-shaped, and has a length of an inch and a quarter; passing through the prostate gland near its upper surface. The caput gallinaginis or veru montanum is a narrow ridge on the bottom of the prostatic portion, three-quarters of an inch long and an eighth of an inch in elevation, containing muscular and erectile tissue. On each side of this are numerous orifices of the prostatic ducts, from the middle lobe of the gland. The prostatic vesicle or sinus pocularis is a fossa a quarter of an inch long, just in front of the veru montanum ; about its margins are the openings of the seminal ejaculatory ducts. This sinus has fibro-musciilar PROSTATE GLAND COWPER'S GLANDS. 93 walls, lined by raucous membrane, on which open a number of small glands. The membranous portion is between the prostate and the bulb of the urethra. This is the narrowest part of the tube except the orifice. From the projection of the bulb below it, it is three-quar- ters of an inch long on its concave roof, and half an inch along its convex floor. It passes through the deep perineal fascia ; and is invested by a double extension from it, and by the compressor urethra muscle. The spongy portion is the longest, having a length of about six inches, to the meatus urinarius. Below the symphysis pubis it ascends a little, and then descends forward. It has an almost uni- form diameter of a quarter of an inch ; except in the bulbous portion, and in the fossa navicularis within the glans penis, in which localities it is dilated. The meatus or orifice is the narrowest part of the canal; its direction is vertical, with two small elevations or labia at its sides. The lining mucous membrane of the urethra has numerous small orifices of mucous glands and follicles, the glands of Littre. These openings are sometimes large enough (lacuna magna] to detain the end of a catheter. Coivper's glands open into the bulbous portion. The muscular coat of the urethra is most abundant in its pros- tatic part. It consists of an outer longitudinal and an inner circular layer of unstriped fibres. Prostate Gland. In shape like a horse-chestnut, and composed of three lobes, this gland lies below and behind the symphysis pubis, around the neck of the bladder and urethra, and upon the rectum. Its trans- verse diameter at the base is an inch and a half; from before backwards, an inch ; depth, three-quarters of an inch. Its lobes are the two lateral and the middle lobe. The middle lobe is normally only a transverse band behind the beginning of the urethra ; sometimes it is absent. In old men it is frequently much enlarged. The prostate gland is dense, though friable, and is surrounded by a fibrous capsule. It it perforated by the seminal ducts. Con- nected with it are circular, unstriped muscular fibres, around the urethra. Its secretion is a milky fluid in appearance, with an acid reaction. Cowper's Glands. These are two lobulated yellowish bodies, each as large as a pea, in front of and under the membranous portion of the urethra, behind the bulb. Their excretory ducts run for almost an inch obliquely forwards, to open into the bulbous part of the urethra. 94 ANATOMY. Penis. This organ consists of the root, body, and gland. The crura or fibrous branches connect the root of the penis with the ram of the pubes. By the suspensory ligament it is held to the front of the symphysis pubis. The glans penis is of a rounded conical form, with the meatus urinarius at its extremity. Behind and below this is the fraenum prceputii, a fold of mucous membrane going backwards to join with the prepuce. The corona glandis is a round projecting border at the base of the gland ; behind this is the narrowing called the neck or cervix. The sebaceous glands of Tyson (glandulce odoriferce} are located around the corona and cervix. The body of the penis is covered by a loose thin-tegument, which forms the prepuce by doubling upon itself at the neck of the gland. Its internal layer, reflected from the cervix over the glans, is of the character of a mucous membrane. The body of the penis is composed of three cylinders of Gbrous and erectile tissue ; the two corpora cavernosa, and the corpus spongiosum. Each corpus cavernosum is composed of a strong fibrous coat, within which is a network of fibres, containing the vascular erec- tile tissue. The bands of fibres are called trabeculce. Between the two corpora is a septum, most complete behind ; in front it is comb-like or pectiniform. In the fibrous outer coat and septum are numerous elastic and muscular fibres ; some of the latter occur also in the trabecalce. The -corpus spongiosum lies below the junction of the corpora cavernosa, inclosing the urethra. It commences between the crura of the penis, in the bulb, and terminates in the glans. The bulb is surrounded by the accelerator uriiise muscle. The structure of the corpus spongiosura is essentially like that of the cavernosa, but with a thinner and more elastic envelope. Erectile tissue is principally formed of a close plexus of small veins, freely communicating with each other. They are largest in size in the middle of each corpus cavernosura. Their blood is returned by the vena dorsalis penis, and by the prostatic and pu- dendal veins. The arteries of the penis come from the internal pudic. The helicine arteries (whose existence is not universally admitted) are convoluted, tendril-like vessels, most abundant in the back part of the penis. The nerves of the penis are branches of the internal pudic nerve and the hypogastric plexus. Its lymphatics are superficial and deep-seated ; some going through the inguinal glands, and others joining the deep pelvic lymphatics. T E S T E S . 95 Fig. 47. Testes. These are oval glands, suspended in the scrotum by the two sper- matic cords. Behind each is a long and narrow body, the epididy- mis ; of which the upper enlarged end (globus major} is connected by its ducts with the upper end of the testicle, and the lower end (globus minor) with its lower end and investing tunic. The left testicle is a little the largest. The coverings of the testicle are, the skin, dartos muscle, exter- nal spermatic fascia, cremaster muscle, fascia propria or infundibu- liform fascia, and tunica vaginalis. The dartos is a thin loose layer of connective tissue mixed with unstriped muscular fibres. The cremaster muscle consists of a few scattered bands of fibres of the internal oblique muscle, carried down in the descent of the testicle. The fascia propria is a similar process of the fascia transversalis. The tunica vaginalis is the serous in- vestment of the testicle, derived from the peritoneum. It is duplicated, over the testis and within the scrotum, the outer layer extending above and below the testis, upon the cord. The immediate fibrous covering the tes- ticle is the tunica albuginea. A partial septum formed by the vertical descent of this tunic into the gland is sometimes called the corpus Highmorianum, or mediastinum testis. The tunica vasculosa is a plexus of blood- vessels lining the tunica albuginea for the supply of blood to the gland. In structure, the testis is composed of from 250 to 400 lobules, of unequal size. Each lobule is conical, and formed of from one to three or four convoluted tubuli seminiferi. These may be unravelled ; and are each seve- ral feet in length with a diameter from ^^o^ n to T |(jth of an inch; they number in all from 300 to 800. Each is surrounded by a plexus of minute capillaries. In the poste- rior apex of each lobule, the tubuli become almost straight, forming the vasa recta, twenty or thirty in number; each of which has a diameter of ^th of an inch. The vasa recta anastomose as they ascend, / ,i I 1(? J-*** KIVUUS UilllOl. JLU. VilS forming the rete testis; at the upper end of deferens . n. VM cuiumaber- which are given off from twelve to fifteen MINCTB STRUCTURE OF THE TESTIS. 1,1. Tunica albugi- nea. 2, 2. Corpus Highrnoria- nuin. 3, 3. Tubuli semini- feri. 4. Vasa recta. 5. Eete testis. 6. Vasa efferentia. 7. Coni vasculosi, the globus major of the epididymis. 8. Body of the epididymis. 9. Its globus minor. 10. Vas 96 ANATOMY. ducts, the vasa efferentia, which pass through the tunica allwginea to the epididymis. By their convolution and enlargraent, in conical masses (coni vasculosi), they make the globus major. Opposite the bases of the cones (each of which is formed by a single duct, six or eight inches long) their ducts open into a single tube or duct, which is very much convoluted, forming the globus minor of the epididymis. The length of this tube when unravelled is more than twenty feet. The vas deferens is the continuation of this duct, upwards from the globus minor, behind the epididymis, and on its inner side. It then goes along, in the spermatic cord, through the external and the inter- nal abdominal rings, into the pelvis. Reaching the base of the blad- der, it becomes enlarged, and then, narrowing at the prostate, joins the duct of the vesicula seminalis to form the ejaculatory duct. The vas deferens is a firm tube, about two feet long, with a canal ^ ? th of an inch in diameter. It has a cellular, muscular, and mucous coat. Vesiculae Seminales. These are lobulated membranous pouches, one on each side, between the bladder and rectum. They are reservoirs for semen, besides having a secretion of their own which mixes with it. Each is about two and a half inches long by half an inch wide; but vari- able in these dimensions. The vesicula seminalis is, in structure, a single tube, convoluted, and giving off irregular branches or diverticula ; all being held together by fibrous tissue. The tube is of the diameter of a goose- quill, and from four to six inches long; behind, it ends abruptly, as a cul-de-sac; in front it is continued as a straight narrow duct, which joins with that of the vas deferens to make the ejaculatory duct. Each ejaculatory duct (one on each side) is about f ths of an inch in length. It commences at the base of the prostate gland, and runs upwards and forwards through its substance, to open into the sinus pocularis of the prostatic part of the urethra. Spermatozoa are minute filaments, found in the liquid of the semen masculinum formed in the testis. Each has an oval enlarge- ment at one end, and a caudal prolongation or extremity ; which shape, with their undulatory movements, suggested the erroneous idea of their being animalcules. Semen also contains, as shown by the microscope, seminal granules, ^VffU 1 of an inch in diameter. Spermatic Cord. This cord is composed of the vas deferens, three arteries, a plexus of veins, the spermatic plexus of nerves, and some large lymphatic vessels ; besides connective tissue, and the cremaster muscle, and fascia. Its course is from the back of the testicle upward to the external abdominal ring (see Hernia), and through the inguinal or spermatic cord to the internal ring, by which it enters the abdominal cavity. ORGANS OF GENERATION IN THE FEMALE. 9 The arteries of the cord are the spermatic, cremasteric, and the artery of the vas deferens. The nerves of the cord are derived from the ganglionic or sym- pathetic plexuses of the abdomen. Descent of the Testes. In early foetal life, the testes are in the abdomen, below the kid- neys. At the lower end of each is a cord, the gubernaculum testis, connected with the scrotum at its lowest part. In the seventh month of gestation, the testicle descends, in the line of the now shortening gubernaculum, through the internal ring, carrying with it a fold of peritoneum ; then through the inguinal canal and exter- nal ring, to enter the scrotum in the course of the eighth month. Just before birth at full term, the peritoneal pouch is closed above ; leaving its fundus to form the tunica vaginalis testes. In the female, the round ligament of the uterus takes a similar course to that of the gubernaculum. At an early period of embryonic life the ovaries and testes correspond in position. ORGANS OP GENERATION IN THE FEMALE. The ovaries are the essential female organs of reproduction, and the uterus is that of gestation. Accessory to these are the Fallo- pian tubes and the external genital organs, i. e., the vagina and its connected parts. Ovaries. Each ovary is an oval body, about an inch and a half long, three-quarters of an inch wide, and a third of an inch in thickness. It is situated in the posterior part of the broad ligament of the uterus, behind and below the Fallopian tube, on either side ; cov- ered by peritoneum, except on its anterior margin, which is at- tached to the broad ligament. It has a fibrous coat, tunica albu- ginea, within which is a soft stroma or fibro-cellular structure well supplied with bloodvessels. Graafian vesicles are from five to twenty small, round, transpa- rent sacs, contained in the ovary. Each, before maturation, holds an ovum, T |^ of an inch in diameter, on the average, surrounded by clear fluid. As it matures, each Graafian vesicle enlarges, ap- proaches the surface of the ovary, and finally bursts; the ovum then escapes through the Fallopian tube into the uterus, and, un- less impregnated, is discharged with the menstrual fluid. Corpus luteum is the name given to the remains of the Graafian vesicle, after its maturation and the discharge of the ovum. Those left after pregnancy are peculiar, and are called true corpora lutea ; those formed at other times, false. The former are larger, firmer, yellower, more vascular, and more puckered in appearance. 9 98 ANATOMY. The ligament of the ovary extends from the upper angle of the uterus to the inner end of the ovary. The round ligaments are two cords, each four or five inches long, below and in frout of the Fallopian tube, between the layers of the broad ligament. Each passes from the upper angle of the uterus, forwards and outwards, through the internal abdominal ring, and along the inguinal canal, to be lost upon the labia majora. Fallopian Tubes. These are two oviducts, one on each side, lying in the free mar- gin of the broad ligament. Each is about four inches long, with a very minute canal, which widens near its outer end, trumpet-like, and then contracts at its termination. The inner end, ostium in- ternum, communicates with the uterus; the outer, ostium abdomi- nale, opens into the cavity of the abdomen. The latter is fringed, and is called the Jimbriated extremity of the Fallopian tube. It is believed to embrace the ovary during sexual excitement. The Fallopian tube has a serous, muscular, and mucous coat. Uterus. The womb, in the virgin, is pear-shaped, flattened before and behind. It is suspended between the bladder and the rectum, by six ligaments of peritoneum. It is about three inches long, two wide at its upper part, and an inch thick. Its upper end is di- Fig. 48. UTERUS AND ITS APPENDAGES. 1. Body of uterus. 2. Fundus. 3. Cervix. 4. Os uteri. 5. Vagina. 6. Broad ligament. 7. Position of ovary. 8. Round ligament. 9. Fallopian tube. 10. Fimbriated extremity of Fallopian tube. 11. Ovary. 12. Ligament of the ovary. 13. Fallopio-ovarian ligament. 14. Peritoneum on anterior surface of uterus. rected upwards and forwards; its lower end, downwards and back- wards, forming an angle with the vagina. Its parts are ihzfundus, body, and neck or cervix. Thefundus is the broad base or upper part; the body narrows VAGINA. 99 from the fundus to the neck. The cervix communicates with the vagina, which is attached around it, extending upwards farther behind than in front. The os uteri or os tincce. is the mouth of the uterus, opening into the cavity of the vagina. Obste- tricians speak also of the os internum, at the upper end of the constriction called the cervix. The cavity of the unimpregnated uterus is quite small. The coats of the uterus are three : serous, muscular, and mucous; the last being its inner lining. It is covered by ciliated columnar epithelium. Numerous follicles and glands exist in the cervix. When distended with fluid, they have been called ovula Nabothi. Ligaments of the Uterus. Two anterior ligaments, or semilunar peritoneal folds, pass between the cervix of the uterus and the posterior surface of the bladder. Two posterior ligaments, also folds of peritoneum, connect the sides of the uterus with the rectum. The two broad ligaments extend from the sides of the uterus to the walls of the pelvis, dividing its cavity into an anterior and a posterior portion. The former contains the bladder, urethra, and vagina; the latter, the rectum. The broad ligaments are con- nected with the peritoneum, and correspond essentially with it in structure. Vagina. This is a musculo-membranous canal, about four inches in length along its anterior wall, longer posteriorly; curved in its direction downwards and forwards from the uterus. Its outlet is called the vulva. It consists of an external muscular, a middle erectile, and an internal mucous coat. The last presents two longitudinal (an- terior and posterior), and numerous transverse ridges or rugce ; also many conical and filiform papilla, besides mucous glands arid follicles, especially at its upper part. The pudendum is a term applied to the vulva and its appendages. The mons veneris is the rounded fatty prominence over the pubes in front, covered with hair after puberty. The labia majora are longitudinal folds, one on each side of the vulva ; reaching from the mons veneris to the perineum. Externally, each is formed of integument; within, of mucous tissue. The two labia are joined in front and behind, by the anterior and posterior commissures. Just within the latter is a small transverse fold, the fourchette. Between it and the posterior commissure is ib& fossa navicularis. The labia minora or nymphce are smaller mucous folds, within the majora ; they pass obliquely from the clitoris above to the sides of the vagina below. The clitoris is a small erectile organ, ana- logous to the penis of the male in its cavernous structure. It is situated just above the vagina. The hymen is a thin semilunar 100 ANATOMY. fold of raucous membrane, across the lower part of the orifice of the vagina. As it is, occasionally, congenitally absent, and has been known to be present in prostitutes, it is not, as was formerly supposed, a test of virginity. Usually, after its rupture, small Fig 49. VISCERA OF FEMALE PELVIS. 1. Symphysis pubis. 2. Abdominal parietes. 3. Mons veneris. 4. Bladder. 5. Entrance of ureter. 6. Urethra. 7. Meatus urinarius. 8 Cli- toris. 9. Left nymplia. 10. Left labium majus. 11. Orifice of vagina. 12, 22. Vaginal canal. 13. Wall between vagina and rectum. 15. Perineum. 16. Os uteri. 17. Cervix. 18. Fnndus. 19. Rectum. 20. Anus. 21. Upper part of rectum. 23. Fold of peritoneum. 24. Reflexion of peritoneum. 25. Last lumbar vertebra. 26. Sacrum. 27. Coccyx. rounded elevations are left around the orifice of the vagina, called carunculce myrtiformes. Urethra in the Female. This canal is much shorter than in the male ; having an average length of an inch and a half. Its direction, also, is different ; being upwards and slightly backwards, with very little curve, behind the pubes. Its external orifice or meatus is in the small triangular space (vestibule), between the clitoris and the upper end of the entrance of the vagina. ORGANS OF CIRCULATION, 101 Mammary Glands. These, as organs of nutrition for offspring, are accessory to the organs of reproduction. In the male they exist, but undeveloped. In the female, each mamma is a true multi-lobular gland. The small- est lobules consist of clusters of rounded vesicles, opening into the smallest branches of the lactiferous (milk-bearing) ducts. These unite into larger ducts, finally making from fifteen to twenty (tubuli lactiferi, or galactophori), which converge towards the areola around the nipple. There they enlarge and form reservoirs for the milk ; and then run from the base of the nipple to its summit, where they perforate it with narrow orifices, by which the milk escapes under pressure. The nipple has a somewhat erectile structure. Fig. 50. SECTION OF MAMMARY GLAND. 1, 1. Galactophorous ducts. 2, 2. Lobuli. CHAPTER VI. ORGANS OF CIRCULATION. HEART. THE heart is a hollow conoidal muscular organ enveloped by the pericardium, and suspended by its great vessels between the lungs; It is situated behind the lower two-thirds of the sternum, its base above and apex pointing downward and to the left side. Its extent is from the level of the upper border of cartilage of the third rib to the space between the fifth and sixth ribs. It is about five inches long, in the adult, by three and a half inches of width in its broadest part, and two and a half inches in thickness. In the male, it weighs from ten to twelve ounces ; in the female, from eight to ten. It increases in size and weight, however, to old age. The heart is essentially twofold, being divided by a muscular septum into the right and left, or respiratory and systemic heart ; conjoined, but not communicating after birth. Each half consists of an auricle and a ventricle. The auricles (named from an ear- like appendage belonging to each) are comparatively thin and weak, the ventricles thick and strong ; thejj^iteiaafll^capacity is 9* 102 ANATOMY. 51. about the same, two fluidounces for each cavity. The auricles are above the ventricles. Most of the anterior surface of the heart is formed by the right ventricle, the left making the apex and left border ; most of the posterior surface is made by the left ventricle. The right auricle is a little larger than the left. It consists of a sinus or main cavity, and an auricular appendix. The ascending and descending vence cavce both open into the right auricle. Between their terminations, on the right wall of the auricle, is a small projection, the tuberculum Loweri. The coronary veins, the largest being sometimes called the coronary sinus, open into the right auricle, bringing blood from the substance of the heart. The apertures of the smaller veins are the foramina Thebesii. At the mouth of the coronary sinus is the valve of Thebesius ; sometimes it is double. Between the front margin of the ascending vena cava and the auriculo- ventricular opening (ostium venosum), is the Eustachian valve, large in the foetus, small in the adult ; it is semilunar, the free edge being concave. The fossa ovalis is a depression marking the place of the fora- men ovale in the foetus, between the right and left auricle. The prominent margin of it is the annulus ovalis. The musculi pectinati are comb-tooth-like fleshy columns, which cross the inner part of the auricu- lar appendix and the contiguous portion of the wall of the auricle. The right ventricle is triangular. It rests below and behind upon the diaphragm. It is separated from the left ventricle by a septum which bulges into the right ventricle. Above, it ends in a small cone (conus arteriosus)-, in which the pulmonary artery begins by a cir- cular opening, guarded by three pocket-like semilunar valves. Each of these pockets is a fold of the lining membrane of the heart, with fibres of ligamentous tissue. At its most prominent part is the corpus Arantii, a small cartilagi- nous prominence, which completes the closure of the valves. Behind each valve is a pouch or dilatation ; these are the sinuses of Valsalva. The columnce carnece are round muscular columns which project from nearly the whole of the inner wall of the ventricle. Some pro- THE LEFT VENTRICLE. 1. Outer side of left ventricle. 2. Outer side of right ventricle. 3. Thickness of its outer pa- rietes. 4. Thickness near the right ven- tricle. 5. Mitral valve. 6,' 7. Columnae carnese with their chordae tendinese. 8. Origin of the aorta. 9. Cavity of the aorta. 10, 10. Superior surface of the right ventricle, showing the ostium ve. nosum audtricuspid valve. 11. Tricuspid valve. 12. Seiuilunar valves of the aorta. HEART. 103 joct only as ridges, others are free except at the ends, while three or four of them give attachment to the chorda tendinece. These, the tendinous chords, are connected with the free surfaces and margins of the three segments of the tricuspid or right auri- culo-ventricular valve. The tricuspid valve is a fold of the lining membrane of the heart, strengthened by fibrous tissue. Its upper margin is attached to the roof of the ostiuin venosnm. The left auricle is cuboidal in form, somewhat smaller but thicker than the right. In structure it resembles the right auricle ; having a sinus, auricular appendix, and musculi pectinati. The four pulmonary veins open into it. The left ventricle is more conical and longer than the right ; its walls are about twice as thick, except near the apex. The aorta opens from this ventricle by a circular orifice, guarded by three semilunar valves, like those of the pulmonary artery, but with larger corpora Arantii, and deeper sinuses of Valsalva. The columnce cornea of the left ventricle resemble those of the right ; two of them, only, connect with chorda tendinece which are attached to the auriculo-ventricular valve. This valve, the mitral valve, consists of but two unequal seg- ments ; but is larger and thicker than the tricuspid. Generally two lesser segments also exist at the place of union of the greater. In structure this valve is similar to the tricuspid. The lining membrane of the heart, the endocardium, is a smooth, thin serous membrane, thickest in the auricles. It covers the valves, and is continuous with the inner coat of the bloodvessels. The muscular fibres of the heart are intricately arranged ; those of the auricles and those of the ven- tricles being mutually independent. The fibres of the auricles are in two layers, the superficial transverse and the deep; the latter being in part looped, and in part annular. The superficial are common to both auri- cles, the deep are peculiar to each. The ventricles also have fibres common to both, and some which are peculiar to each ventricle. The latter are the most common near 'the base of the heart. Fig. 52. INTERIOR OF THE RIGHT VENTRICLE.! . Section of the parietes of the right ven- tricle. 2. Left ventricle. 3. Thickness of the parietes of the right ventricle. 4. Thickness at the commencement of the pulmonary artery. 5. Anterior fold of the tricuspid valve. 6. A portion of the right ventricle. 7, 8. Columnse caroesB with their chordse tendineae. 9. Ven- tricular septum. 10, 11. Cavities between the bases of the columnae earner. 12. Depression leading to the pulmonary ar- tery. 13. Interiorofthepnlmouary artery. 104 ANATOMY. The superficial fibres are mostly spiral in their direction, and placed in layers of unequal thickness. Coiling inwards at the apex of the heart, they there form the vortex, and thence ascend again. The deep fibres are circular in this direction. fibrous rings surround and give fixity to the auriculo-ventricu- lar and arterial openings of the heart. Those of the left side are the strongest. The heart is supplied with blood for its nutrition by the two coronary arteries, anterior and posterior. It has also lymphatic vessels. The nerves of the heart are derived from the cardiac plexus, which is partly ganglionic or sympathetic, and partly cerebro-spi- nal in origin. Minute examination displays a great number of small ganglia on the surface and in the substance of the heart. Pericardium. This sac, which envelops the heart, is composed of an outer fibrous and an inner serous membrane. The fibrous coat is attached, below, to the diaphragm. At the base of the heart, it is extended for some distance over the aorta, pulmonary artery, pulmonary veins , and descending vena cava ; not upon the ascending vena cava. In front, the pericardium lies close to the sternum, covered at the sides by the edges of the lungs, particularly the left. At its sides the pleurae cover it, with the phrenic nerve and vessels between them on each side. Behind, the pericardial sac rests against the bronchial tubes, the descending aorta, and the oesophagus. The serous coat of the pericardium is double ; one layer adhering to the heart, the other lining the fibrous sac. It extends more completely around the aorta and pulmonary artery than around the other great vessels of the heart. Its surface is smooth and moistened with serum. For the route of the circulation of the blood, see PHYSIOLOGY. ARTERIES. Aorta. This, the main trunk of all the arteries of the body, ascends from the upper part of the left ventricle for a short distance, and then forms an arch backwards over the root of the left lung. Thence descending upon the left side of the spinal column, it passes through the dia- phragm into the abdomen ; and finally divides, opposite to the fourth lumbar vertebra, into the right and left primitive or common iliac arteries. It may be divided in description into the arch of the aorta, the thoracic and the abdominal aorta. The arch extends to the lower part of the third dorsal vertebra. Its ascending portion is included in the pericardium. The descend- ing vena cava is to the right of it, the pulmonary artery to its left. PULMONARY ARTERY CORONARY ARTERIES. 105 Below the transverse part of the arch is the left bronchus and the bifurcation of the pulmonary artery. Behind it are the trachea, oesophagus, and thoracic duct. Five branches go off from the arch of the aorta. From the ascend- ing part, the right and left coronary arteries. From the transverse portion, the arteria innominata, left carotid, and left subclavian. In structure, the aorta, like all the other arteries, has an external coat, of connective and fibrous tissue ; a middle coat, of muscular, elastic, and connective tissue ; and an internal co&t, of elastic serous membrane. The muscular fibres of the middle coat are chiefly transverse ; they are of the unstriped variety, pale in color and with spindle-shaped cells and persistent nuclei. The proportion- ate amount of muscular tissue is greatest in the smallest arteries, at a distance from the heart. Branches leave arteries generally at an acute angle ; but this is variable. Anastomosis is the free com- munication which often occurs between two arteries. All arteries have their own nutritious vessels, or vasa vasorum. Pulmonary Artery. This vessel conveys venous or un-aired blood from the heart to the lungs, for aeration. It is about two inches long, chiefly in- closed in the pericardium ; arising in front of the aorta, from the left side of the top of the right ventricle, and passing obliquely upward and backward and to the left, under the arch of the aorta, where it divides into the nearly equal right and left pulmonary arteries. The right pulmonary is rather the larger and longer. This, at the root of the right lung, divides into two branches, one for the upper and middle lobes, and the other and larger, the lower lobe. The left pulmonary artery also ends in two branches, one for each lobe of the left lung. Each of these subdivides into a multitude of ramifications, interpenetrating at last the lobules of the lungs with extremely fine networks of capillaries, for aeration of the blood by the air-cells. Coronary Arteries. The right coronary arises from the aorta just above its valve, and passing in a groove between the right auricle and ventricle, curves around the back of the heart to the posterior groove between the ventricles. There it divides into two branches, which supply the substance of the heart, and anastomose with the branches of the left coronary artery. The left coronary is smaller. It arises above the origin of the right, and descends to the anterior interventricular groove, where it divides, one branch continuing down the groove to the apex, the other winding around to the back of the heart. 106 ANATOMY. Innominata. This, the largest branch of the arch of the aorta, arises near the left carotid from its transverse portion, and, passing for an inch and a half to two inches obliquely up to the right sterno-clavicular junction, there divides into the right subclavian and right primi- tive carotid. To the right of the arteria innominata lie the vena innominata, and pneumogastric nerve; behind, it crosses the trachea. Primitive or Common Carotids. The right carotid arises from the innominata ; the left, from the summit of the arch of the aorta. The latter is thus the longer. Both passing upwards to the neck, their course is thereafter similar. At the level at the top of the thyroid cartilage, each divides into the internal and external carotid. The common caro- tids are separated at the lower part of the neck only by the trachea ; above, by the pharynx, larynx, and thyroid gland. In the same fascial sheath with the common carotid, are included the pneumogastric nerve, and, outside of that, the internal jugular vein ; each having also its special sheath. Below, the common carotid lies deeply, having over it the superficial fascia, platysma myoides muscle, the deep fascia, the sterno-cleido-mastoid, sterno-hyoid, sterno-thyroid, and, by the cri- coid cartilage, the omo-hyoid muscles. Near its bifurcation above, it is bounded within a triangular space, behind which is the sterno- cleido-mastoid, above, the belly of the digastric muscle, and below, the omo-hyoid. A small artery and several veins cross it, and the descendens noni nerve lies upon or within its sheath. The sym- pathetic nerve is behind it, between it and the reclus anticus major muscle, which rests upon the spine. At the lower part of the neck, the internal jugular vein of the right side leaves the artery ; but that on the left side comes near to and often crosses it. External Carotid. From the division opposite the top of the larynx, this vessel curves upwards and forwards and then backwards, to divide between the neck of the condyle of the lower jaw and the external meatus or orifice of the ear, into the temporal and internal maxillary arteries. At its beginning, the external carotid has behind it the sterno- cleido-mastoid muscle ; below, the omo-hyoid ; and above, the digas- tric and stylo-hyoid muscles. The hypoglossal nerve and lingual and facial veins cross it, as well as the digastric and stylo-hyoid mus- cles. It is covered, under the skin, by the platysma myoid muscle, the deep fascia, and the front edge of the sterno-cleido-mastoid. Above, the external carotid passes into the substance of the EXTERNAL CAROTID. lOf parotid gland ; lying there under the facial nerve, and the union of the internal maxillary and temporal veins. Between it and the internal carotid is part of the parotid gland, as well as the stylo- glossus and stylo-pharyngeus muscles. Eight branches leave the external carotid artery; divisible into four sets, as follows : Anterior, the superior thyroid, lingual, and facial; posterior, the occipital and posterior auricular; ascending, the ascending pharyngeal ; and terminal, the temporal and internal maxillary. Deviations or variations may occur (as in all parts of the arterial system) in the origin and distribution of these vessels ; it is their normal or most general course that is described. Superior thyroid curves upwards and then down to the thyroid gland ; dividing into four branches also, the hyoid, superficial de- scending, laryngeal, and crico-thyroid. Lingual ascends inwards to the greater cornu of the os hyoides, and, reaching the tongue, gives off the hyoid, dorsalis linguae, sub- lingual, and ranine branches ; the latter going to the tip of the tongue. Facial is a tortuous vessel, which, passing up through the sub- maxillary gland, then crosses the margin of the lower jaw-bone, in front of the insertion of the masseter muscle ; thence it goes across the cheek and up the side of the nose to the inner angle of the eye. Branches of the facial are ten in number ; of which the principal are the submaxillary , submental, inferior labial, superior and inferior coronary (around the lips), and the lateral nasal artery. Muscular branches also go to the masseter and other muscles. Occipital arises opposite to the facial, and passes behind the mastoid process, and thence upwards tortuously upon the occiput to divide about the vertex into many branches. Not far from its origin the hypoglossal nerve winds around it. Posterior auricular is small ; it goes beneath the parotid gland between the ear and the mastoid process ; then dividing into the anterior and posterior branches, which anastomose with the tem- poral and occipital; also giving off the stylo-ma stoid branch to the foramen of that name, and the auricular to the ear and lesser branches. Ascending pharyngeal is yet smaller but long, and deeply seated. It ascends between the internal carotid and the pharynx. Its branches are muscular and nervous, pharyngeal and meningeal. The latter pass through foramina in the base of the cranium to the dura mater. Temporal appears as a continuation upwards of the external carotid, from the parotid gland. Two inches above the zygomatic arch it divides into the anterior and posterior temporal ; first giving off the transverse facial, anterior auricular, and middle temporal. 108 ANATOMY. Internal maxillary is larger than the temporal. It goes inwards at right angles to the latter, within the condyle of the lower jaw- bone; having three sets of branches : 1. from the maxillary part, tympanic, middle meningeal, small meningeal, and inferior dental ; 2. from the pteryyoid part, deep temporal, pterygoids, masseteric, and buccal; 3. from the terminal part, alveolar, infra- orbital, poste- rior palatine, vidian, pterygo-palatine, and nasal or spheno-palatine. Internal Carotid. From the border of the thyroid cartilage this vessel ascends vertically to the carotid foramen in the petrous part of the tem- poral bone. Entering this, it soon winds forwards and inwards through the carotid canal, and then, near to the anterior clinoid process of the sphenoid bone, it pierces the dura mater and sub- divides into branches. These are, the tympanic, anterior meningeal, ophthalmic, ante- rior cerebral, middle cerebral, posterior communicating, and anterior choroid. . The ophthalmic enters the orbit with the optic nerve, through its foramen, and getting on the inner wall of the orbit, passes to the inner angle of the eye, where it divides into the frontal and nasal branches. Other branches of the ophthalmic are, the lachrymal, supra- orbital, two ethmoidal, palpebral, three ciliary, and the central artery of the retina. The supra-orbital is largest of these ; it runs through the supra- orbital foramen of the frontal bone. The nasal artery anastomoses with the terminal branch of the facial. The anterior cerebral artery, leaving the internal carotid at the base of the brain (near the fissure of Sylvius), runs forwards in the fissure between the cerebral hemispheres ; the two anterior cere- bral, right and left, having a short connecting trunk, the anterior communicating artery. Then they curve over the front edge of the corpus callosum, and upon its upper surface, to connect with the posterior cerebral. The middle cerebral is larger. It goes obliquely outwards along fBe fissure of Sylvius, in which it divides into three branches. The posterior communicating artery runs back from the internal carotid to anastomose with the posterior cerebral. The anterior choroid goes to the choroid plexus, and the parts of the brain near it. Subclavian Artery. On the right side, the subclavian comes from the innominata ; on the left, from the aorta. For a short distance, they differ ; then, their description becomes the same. The right subclavian passes from its origin opposite the sterno- VERTEBRAL ARTERY. 109 clavicular articulation upwards and outwards to the inner edge of the scalenus anticus muscle. It is here covered, in front, by the skin, superficial fascia, platysma myoides, deep fascia, sterno-cleido- mastoid muscle, sterno-hyoid and sterno-thyroid muscles. The in- ternal jugular and verterbral veins cross it; as also do the pneumo- gastric, phrenic, and some branches of the sympathetic nerves. Beneath it is the pleura ; behind it, the longus colli muscle, the sympathetic, and the transverse process of the third cervical ver- tebra. The recurrent laryngeal winds around its lower part. The left subclavian arises opposite the second dorsal vertebra, from the transverse portion of the arch of the aorta ; and ascends to the first rib, behind the insertion of the scalenus anticus muscle. In front of it are the pleura, left lung, pneumogastric and phrenic nerves and cardiac branches of the sympathetic, left carotid artery, left internal jugular and innominata veins, sterno-hyoid, sterno- thyroid and sterno-cleido-mastoid muscles. Behind it, the oesophagus, thoracic duct, inferior cervical ganglion of the sympa- thetic, longus colli muscle, and spinal column. Outside of it is the pleura ; on its inner side, the oesophagus, trachea, and thoracic duct. Reaching the scalenus anticus muscle, and passing over the first rib between that muscle and the scalenus medius, the right and left subclavian arteries thenceforth have the same course ; both being, like other vessels, subject to occasional variation or anomaly. The most superficial part of the subclavian lies in a triangle, whose base in front is the scalenus anticus ; one side above, being the orno-hyoid muscle, and the other the clavicle, below. The external jugular vein crosses it on the inner side, receiving there two venous branches. The subclavian vein lies below the artery, behind the clavicle. The four branches of the subclavian artery are, the vertebral, internal mammary, thyroid axis, and superior intercostal. Vertebral Artery. This, the largest branch of the subclavian, enters the foramen in the transverse process of the sixth cervical vertebra, and passes through the corresponding foramina of the upper five vertebrae, to enter the head through the foramen magnum occipitis. In front of the medulla oblongata it forms, by union with the opposite one, the basilar artery. Before this, it gives off lateral spinal and muscular branches. Within the cranium, the vertebral sends off the posterior meningeal, anterior and posterior spinal, and inferior cerebellar. The last is the largest. The basilar artery extends from the posterior to the anterior border of the pons Varolii ; there it divides iuto the two posterior 10 110 ANATOMY. cerebral arteries. On each side it gives off the transverse, anterior, and superior cerebel/ar. The circle of Willis is the anastomosis, at the base of the brain, between the basilar artery and the internal carotid and its branches. Thyroid Axis. This is a large but short vessel, dividing into the inferior thyroid, supra-scapular, and transversalis colli. The inferior thyroid goes to the thyroid gland, giving off as branches the laryngeal, tracheal, cesophageal, and ascending cervical. The supra- scapular and transversalis colli have principally a mus- cular distribution. Internal Mammary. This artery descends from the subclavian behind the clavicle to the inner surface of the costal cartilages, near the sternum ; be- tween the sixth and seventh cartilages, it divides into the musculo- phrenic and superior epigastric. Besides these, its branches are the superior phrenic, mediastinal, pericardiac, sternal, anterior intercostal, and perforating arteries. Superior Intercostal. Last branch of the subclavian, this goes backwards, sending off the deep cervical to descend in front of the first and second ribs, at their necks, and anastomoses with the first aortic intercostal. It sends a branch also along the first intercostal space, and one for the second, which joins on the aortic branch. Each of these sends branches to the spinal cord. Axillary Artery. The continuation of the subclavian, this vessel passes from the lower edge of the first rib, to become the brachial as it passes the border of the tendons of the latissimus dorsi and teres major muscles. Yery deep at first, it is afterwards almost superficial. In the former position, it has in front of it the pectoralis major muscle, costo-coracoid fascia, and cephalic vein. Behind it, the first intercostal muscle, serratus magnus muscle, and posterior tho- racic nerve. Outside of it is the brachial nervous plexus. Inside of it, the thoracic vein. Next, it passes under the pectoralis minor muscle, having, in front, also, the pectoralis major ; behind, the subscapularis ; inside of it, the axillary vein. Lastly, the axillary lies still below the pectoralis minor, with the lower edge of the pectoralis major covering it, \nfront, only above ; the skin and fascia, only below. There, it has behind it the subscapularis muscle, and tendons of the latissimus dorsi and teres major ; outside of it the median nerve, and BRACHIAL ARTERY. Ill part way, the muscnlo- cutaneous nerve ; on the inner side, the ulnar, in- ternal cutaneous and lesser internal cutaneous nerves ; behind, the mus- culo-spiral and circum- flex nerves. Branches of the axil- lary are, fast, the supe- rior thoracic and aero- mial thoracic ; secondly, the thoracica longa and thoracica alaris ; lastly, the r subscapular and an- terior and posterior cir- cumflex arteries. The thoracica longa goes downwards and in- wards to the muscles at the side of the chest. The snbscapulur is the largest branch of the axillary. The circumflex arteries wind around the neck of the humerus. Brachial Artery. From the margin of the teres major tendon this passes down on the inside of the humerus, coming forward gradu- ally near the elbow, to divide there into the radial and ulnar arteries. Fig. 53. Ti . c i i i artery. It IS Superficial through- op E ARM AND SHO^DER.-I. Axillary 2. Thoracica acromialis. 3. Thoracica supe- rior Sub . scapularis branch . 5. Inferior scapul*. OUt, Covered in front by 6; 7. Branches to the teres and sub-scapularis muscles. the Skin and Superficial 8. Anterior circumflex. 9. Brachial artery. 10. Pro- and deep faSCiaB it has funda ma J r humeri. ll. Posterior circumflex. 12. the basilic Vein tO He near MaiQ tru k f the P'funda major. 13. Muscular bran- .. ... ches. 14. Branches to the brachiahs intern us. 15. Ke- itS line, the median nerve currens ulnaris anastomosing with the anastomotica of tO CrOSS itS middle, and thebrachial. the bicipital fascia to separate it, near the elbow, from the median basilic vein. Behind the brachial, the long and inner heads of the triceps ex- tensor muscle, and the superior profunda artery and musculo-spiral 112 ANATOMY. Fig. 54. nerve, come between it and the humerus. Outside of it, besides the median nerve, lie the biceps flexor and coraco-brachialis mus- cles; over the insertion of the latter of which, and thebrachialisanti- cus, the bifurcation of the artery occurs. The place of this (bifur- cation), however, is especially subject to anomaly. Inside of the brachial are, above, the internal cutaneous and ulnar nerves ; below, the median nerve. Accompanying it in its course with crossing branches, are the two vence co mites. It is, usually, opposite to the coronoid process of the ulna that the brachial, having sunk there into a triangular space, divides into the radial and ulnar. If devi- ation exist, it is, most frequently, above the normal point. The branches of the brachial are, the superior or major pro- funda, nutritious artery, profunda minor or inferior, anastomotic and muscular branches. Radial Artery. Smaller, and more superficial than the ulnar, the radial passes along the outer side of the fore- arm, guarded by muscles and ten- dons ; especially by the supinator radii longus and flexor carpi radialis. At the wrist, it winds around the carpus, under the extensor tendons of the thumb, to the interosseous space behind. Two vence comites, and a filament of the musculo-cutaneous nerve, accompany the radial artery. In {\\eforearm, the branches of the radial are, the radial recurrent, muscular, superficialis voids, and ONE OP THE ANOMALIES IN THE BRA- CHIAL ARTERY. 1. Termination of the axillary artery. 2. Brachial artery 3, Radial artery. 4, 4. Ulnar artery. 5. anterior carpal. A recurrent branch. 6. Anterior inter- osseous artery. 7. Superficial palmar arch. 8. Deep-seated palmar arch. Anastomosis of the two arteries. In 'the wrist, the posterior carpal, mctacarpal, dorsales polli- cis, and dorsolis indicis. ULNAR ARTERY ABDOMINAL AORTA. 118 In the hand, the princeps pollicis, radialis indicis, perforating, and interosseous arteries. The deep palmar arch is the termination of the radial ; it joins with a communicating branch of the ulnar. TTlnar Artery. This runs along the ulnar border of the forearm, becoming near the wrist more deep-seated than the radial ; it ends in the palm of the hand by forming the superficial palmar arch ; this anastomoses with the superficialis voice. The branches of the ulnar artery are, in the forearm, the ante- rior and posterior ulnar recurrent, the anterior and posterior inter- osseous, and muscular branches. In the wrist, the anterior and posterior carpal. In the hand, the communicating or deep branch, and the digital arteries. The recurrent arteries, both radial and ulnar, anastomose with vessels proceeding from above towards the hand. The digital arteries are four ; going off from the superficial palmar arch, to the sides of the index, middle, ring, and little fingers ; lying beneath the digital nerves. At the middle of the last phalanx of each finger, an arch is formed by the meeting of these with the interosseous arteries, from the deep palmar arch. Branches from this anastomosis pass to the matrix of the finger nail. Thoracic Aorta. From the lower edge of the third dorsal vertebra, on the left side of the spinal column, the aorta descends to the diaphragm ; which it penetrates near the last dorsal vertebra. This course is in the posterior mediastinum ; having near it, the left lung, pleura, pulmonary artery, and bronchus, the pericardium and oasophagus, the thoracic duct, the vena azygos major and vena azygos minor. Branches of the aorta in the thorax are, the pericardiac, bron- chial, cesophageal, posterior mediastinal, and intercostal. The bronchial arteries, various in number, usually one for the. right side and two for the left, are the nutritious vessels for the lungs. They go to join and follow the bronchial tubes in their distribution. The intercostal arteries are normally ten on each side, longest on the right. Going to the intercostal spaces, below the first, each di- vides into an anterior and a posterior branch ; small fibrous arches protect these vessels from pressure by the intercostal muscles. Abdominal Aorta. From the aortic opening in the diaphragm, the aorta goes down on the left side of the spinal column to the fourth lumbar vertebra. There it divides into the right and left common or primitive iliac arteries. The ascending vena cava lies to the right of it, with the vena azygos, thoracic duct, and right semilunar ganglion*, on its left are the sympathetic nerve and left semilunar ganglion. 10* 114 ANATOMY. The branches here are separable into 1, visceral ; and 2, parietal, i.e., for the abdominal walls. The first are the cceliac axis, superior and inferior mesenteric, supra-renal, renal, and spermatic. The second group, the phrenic, lumbar, and median sacral arteries. Cceliac Axis. This arises near the margin of the diaphragm, and, after a course of half an inch, divides into the gastric, hepatic, and splenic arteries. The gastric is smallest. It goes up, and to the left, to the cardiac end of the stomach, and then along its lesser curvature, some of its branches joining those of the hepatic and splenic ; others go to the oesophagus. The hepatic is next in size in the adult. It passes to the right side, into the transverse fissure of the liver, where it divides into a right and a left branch, whose ramifications accompany those of the portal vein into the substance of the liver. Its branches are the pyloric, g astro- duodenal, and cystic. The splenic is a large and tortuous artery. Besides supplying the spleen, it sends blood to the cardiac end of the stomach, by the vasa brevia and the aastro-epiploica sinistra, and to the pancreas, by the pancreatica maana and pancreaticce parvae. Superior Mesenteric. By this vessel nearly the whole of the small intestine is sup- plied, as well as the caecum and colon. Going between the pan- creas and duodenum, it crosses and descends in an arched form to end in the right iliac fossa. The superior mesenteric vein and plexus of nerves accompany it. Besides a branch to the pancreas and duodenum, and twelve or more branches to the small intestine, it gives off also the ileo- colic, colica dextra, and colica media. Inferior Meeenteric. This branch of the aorta supplies the descending colon, its sig- moid flexture, and most of the rectum. It terminates in the superior hemorrhoidal artery, sending off, also, the colica sinistra and sigmoid. The superior hemorrhoidal divides into small branches only when it has reached, at the posterior part of the rectum, a distance of about four inches from the anus. Supra-renal Arteries. These are, though large in the foetus, small in the adult. There js one for the right and one for the left supra-renal capsule. Renal or Emulgent Arteries. Each kidney receives a large trunk from the aorta, leaving it almost at a right angle. The left one arises aboye the right, but SPERMATIC PHRENIC INTERNAL ILIAC. 115 the right is somewhat the longest. Before entering the kidney, each artery divides into several branches. Spermatic. In the male, this artery on each side goes to the testicle ; in the female, to the ovary. It is longer in the male, and quite tortuous, attending the spermatic cord in its course through the abdominal rings. Phrenic. Varying a good deal in its origin, the phrenic artery chiefly supplies the diaphragm; some branches, however, going from it to the supra-renal capsule, the spleen on the left side, and the liver on the right. Lumbar Arteries. Four of these go on each side, nearly at right angles from the aorta, and outwards and backwards, around the lumbar vertebra. Between the transverse processes, each divides into an abdominal and a dorsal branch. Middle Sacral Artery. A small branch, from the bifurcation of the aorta, passing down in front of the last lumbar vertebra and the middle of the sacrum, to anastomose, about the upper end of the coccyx, with the lateral sacral arteries. Some of its ramifications go to the rectum, and others enter the anterior sacral foramina. Common Iliac. The primitive or common iliac artery, on each side, is about two inches in length ; the right being somewhat the largest. They diverge from the aorta at the fourth lumbar vertebra, outwards and downwards; dividing, opposite the junction of the last lum- bar vertebra and the sacrum, into the external and internal iliacs. Two common iliac veins accompany each. The lateral branches of the common iliac arteries are small and local. Internal Iliac. This is a short but thick artery, an inch and a half long. At the top of the great sacro-sciatic foramen, it divides into a large ante- rior and a similar posterior branch. From this bifurcation, the cord- like remainder of the hypogastric artery of the foetus extends to the bladder. From the anterior trunk pass off, as branches, the superior, middle, and inferior vesical, middle hemorrhoidal, obtu- rator, internal pudic, and sciatic; and, in the female, the uterine and vaginal arteries. From the posterior trunk go the gluteal t ilio-lumbar, and lateral sacral. 116 ANATOMY. The middle hemorrhoidal goes to the rectum ; anastomosing with the other hemorrhoidal vessels. The obturator artery sometimes arises from the posterior branch of the internal iliac; generally from the anterior. Passing out of the pelvis through the obturator foramen, it divides into an in- ternal and an external branch. Its other branches are small. The internal pudic supplies the external genital organs. Be- sides muscular, nervous, and visceral branches given off within the pelvis, it sends off after its emergence through the great saero- sciatic notch or foramen, the inferior hemorrhoidal, superficial, and transverse perineal, the artery of the bulb, the artery of the corpus cavernosum, and the dorsalis penis. Remark, however, that the internal pudic re-enters the pelvic cavity by the lesser sacro-sciatic foramen ; afterwards, crossing to the ramus of the ischium, to ascend it and run along the inner margin of the ramus of the pubes. Its terminal branches are the artery of the corpus cav- ernosum and the dorsalis penis. The transverse perineal artery accompanies the transversus perinei muscle. Sciatic Artery. This is the larger of the two terminal branches of the anterior trunk of the internal iliac; the internal pudic being the other. The sciatic supplies the posterior muscles of the pelvis. Gluteal Artery. The gluteal is the largest branch of the internal iliac. Short and thick, it leaves the pelvis above the pyriformis muscle ; then dividing into a superficial and a deep branch. The superficial passes under the gluteus maximus muscle, and subdivides. The deep branch goes between the gluteus medius and gluteus minimus muscles, and divides into two. Ilio-Lumbar. This branch of the posterior trunk of the internal iliac ascends beneath the psoas muscle and internal iliac artery and vein, to di- vide, in the iliac fossa, into a lumbar and an iliac branch. Lateral Sacral. These are commonly two on each side; the superior and the inferior lateral sacral, branches of the posterior trunk of the in- ternal iliac. External Iliac Artery. Larger in the adult than the internal iliac, the external iliac artery passes downwards and outwards along the psoas muscle to EPIGASTRIC ARTERY FEMORAL ARTERY. 117 the margin of the pelvis, half way between the anterior superior spine of the ilium and the symphysis puhes. There emerging from the pelvis to enter the thigh, it becomes the femoral artery. At the femoral arch, the femoral vein lies at its inner side ; the ante- rior crural nerve is outside and in front of it. The most important branches of the external iliac are the epi- gastric and the circumflex iliac. Epigastric Artery. This vessel arises a few lines above Poupart's ligament (border of the tendon of external oblique muscle) and after a short descent it passes obliquely upwards and inwards between the transversalis fascia and the peritoneum, to the margin of the rectus abdominis muscle. Penetrating its sheath it ascends behind that muscle, sub- dividing, and anastomosing finally with branches of the internal mammary and intercostal arteries. The branches of the epigastric artery are the cremasteric, pubic, and muscular branches. The occasional variations in the origin of the epigastric are important in the surgical anatomy of hernia. Circumflex Iliac. Arising from the outside of the external iliac, nearly opposite to the epigastric, this artery runs to the crest of the ilium, to anasto- mose afterwards with the gluteal and ilio-lumbar arteries. Femoral Artery. This continuation of the external iliac, passing under Poupart's ligament down the front and inside of the thigh, runs, at the junction of the middle and lower third of the thigh, through an opening in the adductor magnus muscle, to become the popliteal artery. Its course may be marked by a line drawn from a point half way between the anterior superior spine of the ilium and the symphysis pubis to the internal condyle of the femur; to which line the femoral artery lies parallel. The femoral is superficial in the upper third of the thigh. Its location is there sometimes called Scarpa's triangle. The apex of this space is below ; the inner side is the line of the adductor longus muscle, the outer, the sartorius muscle, and the base, Pou- part's ligament. The iliacus, psoas, pectineus, and adductor longus muscles principally form the floor of the triangular space, which is bisected by the femoral vessels, from the base to the apex. The femoral artery and vein are inclosed together in a strong fibrous sheath, made partly by a process of {he fascia lata of the thigh ; but each vessel has also its thinner sheath. In the middle third of the thigh the femoral is more deeply 118 ANATOMY. Fig. 55. seated. Over it is the sartorius muscle, inside of it the adductor longus and adductor raagnus, and outside of it the vastus interims muscle. The femoral vein here lies to the outside of it ; and just be- yond that is the long or internal saphenous nerve. The branches of i\\e femoral ar- tery are the superficial epigastric, superficial circumflex iliac, super- ficial external pudic, deep external pudic, prof undo, femoris, muscu- lar, and anastomotica magna. The superficial epigastric ns- cends through the saphenous opening of the fascia lata, to pass over the external oblique muscle of the abdomen, in the superficial fascia, to the umbili- cus. Its subdivisions anastomose with those of the deep epigastric and internal mammary arteries. The profunda femoris, nearly as large as the femoral, arises from its outer and back part, an inch or two below Poupart's liga- ment. Passing to the inner side of the femur, it goes through the adductor magnus muscle to the back of the thigh. Its main branches are the external and internal circumflex, and the three perforating arteries. The external circumflex goes to the muscles on the front of the thigh. The internal circumflex winds round the femur to supply a number of muscles. The three perforating arteries go through the tendons of the adductor bre- vis and adductor magnus mus- cles. The muscular branches of the femoral, from two to seven, go principally to the sartorius and vastus interims. The anastomotica magna is the last to leave the femoral before ARTERIES OF THE PELVIS AND THIOH. 1. Inferior extremity of abdominal aorta. 2. Right primitive iliac. 3. Right exter- nal iliac. 4. Epigastric artery. 5. Cir- curnflexa ilii. 6. internal iliac. 7. Ileo lumbar. 8. Gluteal. 9. Obturator. 10. Lateral sacral. 11. Vesical arteries cut off. 12. Middle hemorrhoidal. 13. In- ternal pudic. 14. Ischiatic. 15. Origin of femoral artery. 16. Point where it passes through the adductor muscles. 17. Profunda major. 18. Internal circumflex. ANTERIOR TIBIAL ARTERY. 119 it becomes the popliteal. It divides into two branches ; the deeper of which has some ramifications reaching to the knee-joint. Popliteal Artery. From the opening in the adductor mag- nus muscle the popliteal goes obliquely outwards and downwards, behind the knee, to divide, at the lower edge of the popliteus muscle, into the anterior and posterior tibial arteries. Over the popli- teal, at first, lies the semi-membranosus muscle; lower, it is covered by the gas- trocnemius, soleus, and plantaris muscles, the popliteal vein, and internal popliteal nerve. Branches of the popliteal are the supe- rior muscular, inferior muscular or rural, cutaneous, superior external and internal articular, azygos articular, inferior exter- nal and internal articular. Anterior Tibial Artery. This vessel passes from the bifurcation of the popliteal, between the heads of the tibialis posticus muscle, and between the tibia and fibula, to the deep part of the front of the leg. It then goes down on the interosseous ligament and tibia, be- coming more superficial in front of the ankle, as the dorsalis pedis. It has two venae comites, one on each side. Its branches are the recurrent tibial, muscular, internal malleolar, and external malleolar. Its terminal continuation, the dorsalis pedis artery, runs along the tibial side of the foot to the first inter-metacarpal space ; there it divides into the dorsalis hallucis and the communicating artery. Other branches of it are the tarsal, meta- tarsal, and inter osseal vessels. The dorsalis hallucis divides into two branches, one for the inner side of the great toe, and the other for the adjoining sides of the great and second .toes. Fig ANTERIOR TIBTAL ARTERY. 1,1. Extensor propriuspollicis pedis muscle and tendon. 2, 2. Articular arteries. 3. Anterior tibial artery. 4, 5. The same artery. 6. Recurrent branch. 7. Branch to muscles. 8, 8. Other muscular branches. 9. Pedal artery, or continuation of the anterior tibial on the foot. H. External malleolar artery. 120 ANATOMY. The communicating artery dips down into the sole of the foot, to an- astomose with the external plantar artery, forming the plantar arch, and giving off two digital branches, for the great and second toes. Posterior Tibial. From the popliteus muscle this artery goes along the tibia! side of the leg, behind the tibia, to the fossa between the inner malleolus and the heel ; there to divide into the internal and external plantar. Covered above by the gastrocnemius and soleus muscles, in its lower third it is covered only by the skin and fascia, on the inner side of the tendo Achillis. It has two companion veins. The posterior, tibial nerve lies above, on the inner side of the artery ; soon it crosses it, and lies chiefly on its outer side. The branches of the posterior tibial artery are the peroneal, muscular, nutritious, communicating, and internal calcanean. Peroneal Artery. This vessel leaves the posterior tibial about an inch below the popliteus muscle. It goes obliquely outwards to the fibula, and descends along its inner border to the lower third of the leg ; there it sends off the anterior peroneal, which pierces the interos- seous ligament to pass down the front of the leg to the tarsus. The other branches of the peroneal are muscular. Plantar Arteries. These are the terminal branches of the posterior tibial. The external plantar is the larger. It goes, from the space between the inner ankle and the heel, outwards and forwards to the base of the last metatarsal ; then it turns inwards to the space between the first and second metatarsal bones, to complete the plantar arch by joining the communicating branch of the dorsalis pedis. The internal plantar passes forwards along the inner side of the foot, and inner border of the great toe ; anastomosing with its digital branches. From the plantar arch the largest branches of many, are the three posterior perforating, and the four digital vessels. The latter, at the bifurcation of the toes, send off the anterior perforating branches, to join the interosseous branches of the metatarsal artery. Both sides of the three outer toes, and the outer side of the second toe, are supplied by branches from the plantar arch ; both sides of the great toe, and the inner side of the second, by the dorsalis pedis artery. VEINS. The capacity of the venous system is nearly three times as great as that of the arterial ; the veins being both larger and more numerous than the arteries. The veins communicate very freely with each other. Each vein has three coats ; internal, middle, and EXTERIOR VEINS OF THE HEAD. 121 external. Thejrs, like that of the arteries, is composed of con- nective tissue and epithelium, resembling serous tissue. The middle coat contains less muscular and elastic tissue than that of the arteries. The muscular tissue is greatest in amount in the larger veins, near the heart. The external coat is much like that of the arteries, but thinner, and contains longitudinal muscular fibres. Most veins have valves, at intervals along their course, formed of projections or folds of the middle and inner coats, semilunar in shape. They open only towards the heart. Valves are most numerous in the veins of the lower limbs. There are no valves in the smallest veins, nor in the venae cavse, hepatic vein, portal vein, pulmonary, cerebral, spinal, renal, uterine, and ovarian veins ; nor in the umbilical vein of the fcetus. Veins have nutritious vessels, or vasa vasorum, like the arteries. Exterior Veins of the Head. These are the facial, temporal, internal maxillary, temporo- maxillary, posterior auricular, and occipital veins. The facial vein runs from the inner angle of the eye obliquely across the face to the front edge of the masseter muscle. Its origin is in the frontal vein, which descends near the middle of the forehead ; those of the two sides, at first parallel, uniting at the root of the nose by the transverse trunk called the nasal arch. The facial vein, lying outside of the facial artery, crosses the jaw, and in the neck joins with a branch from the temporo-maxil- lary vein to empty into the internal jugular. The facial receives as branches, some from the pterygoid plexus, and the inferior palpebral, labial, buccal, masseteric, submental, inferior palatine, submaxillary, and ranine veins. The temporal vein begins on the side of the head in a minute plexus, the trunk from which, above the zygoma, is joined by the middle temporal vein. The temporal vein goes down between the. ear and the condyle of the jaw, enters the parotid gland, and joins the internal maxillary vein to form the temporo-maxillary. The branches of the temporal are small, except the transverse facial, from the side of the face. The internal maxillary is a considerable vein, whose branches correspond with those of the internal maxillary artery; being the middle meningeal, deep temporal, pterygoid, masseteric, buccal, pala- tine, and inferior dental. The temporo-maxillary vein, formed by the union of the last two, divides in the parotid gland into two branches, one of which joins the facial, and the other the external jugular. The posterior auricular, beginning on the side of the head, by a plexus, descends behind the ear to empty into the temporo-maxil- lary vein. The occipital vein commences in a plexus at the back of the 11 122 ANATOMY. head, and follows the course of the occipital artery, beneath the muscles of the neck, to, and generally in the internal jugular ; sometimes in the external jugular. By the mastoid vein, it com- municates with the lateral sinus of the dura mater. Veins of the Neck. These are the external jugular , posterior external jugular, ante~ tior jugular, internal jugular, and vertebral. The external jugular vein is a continuation of the temporo-maxil- lary and posterior auricular, from the parotid gland down the neck to the middle of the clavicle. There it penetrates the deep fascia to join the subclavian vein. Sometimes it is double. The posterior external jugular descends at the bacjj of the neck to empty into the external jugular. The anterior jugular goes down on the inner side of the anterior edge of the sterno-cleido-mastoid muscle, to join the subclavian. It varies in size. The internal jugular vein is formed in the jugular foramen at the base of the skull, by the junction of the lateral and inferior petrosal sinuses. It passes down the neck, outside of the carotid artery, to join the subclavian at the root of the neck, thus forming the vena innominata. Its branches are the facial, lingual, pharyngeal, superior and middle thyroid, and occipital veins. The vertebral vein, beginning in the occipital region, goes through the foramina of the transverse processes of the upper six cervical vertebra; then emptying into the vena innominata. Veins of the Interior of the Skull. The diploe of the cranium has a number of tortuous canals, con- taining large veins with thin walls, enlarged at intervals into pouches. They communicate with the sinuses of the dura mater, and with the exterior veins of the head. The cerebral vein has thin coats, without muscular tissue, and without valves. They are superficial and deep ; eight or ten in number. They and the cerebellar veins empty into the sinuses of the dura mater. The sinuses of the dura mater are channels for venous blood, having for their outer coat the dura rnater itself. They are twelve ; five at the upper and back part of the skull, and seven at the base of the skull. The first named are the superior and inferior longitudinal, the straight, lateral, and occipital sinuses. The superior longitudinal sinus runs backwards from the crista galli of the ethmoid bone, making a groove in the frontal, the junction of the parietal, and the occipital bones. At the crucial edge of the last, it divides into the two lateral sin uses. The glands of Pacchioui are small white bodies projecting from the inner sur- VEINS OP THE ARM AND HAND. 123 face of this sinus. The junction of the three sinuses just named is the torcular Herophili. The inferior longitudinal sinus or vein occupies the back and free part of that fold of the dura mater called falx cerebri. It ends in the straight sinus. The straight sinus is at the junction Fig. 57. of the/ata with the tentorium. It joins the other sinuses at'the torcular Hero- phili. The lateral are two large sinuses, passing from the torcular first outwards, and then coming downwards and inwards to empty into the jugular vein at the jugular foramen. The right one is larger than the left. The occipital sinuses are the smallest. They are in the attached margin of the falx cerebelli, and end at the torcular Herophili. The sinuses at the base of the cra- nium are the cavernous, circular, supe- rior and inferior petrosal, and trans- verse. The circular and transverse communicate, near the middle of the base of the skull, between the sinuses of the two sides. The cavernous are short and longitudinal ; with a reticulated structure. Veins of the Arm and Hand. These are superficial and deep. The first begin chiefly on the back of the head. The last are the vence comites of the arteries. Superficial are the anterior ulnar, posterior ulnar, basilic, radial, cephalic, median, median basilic, and median ce- phalic veins. The anterior ulnar and posterior ulnar, named from their situation, join at the ^SUPERFICIAL VEINS OP THE UPPER EXTREMITY. 1. Axillary artery. 2. Axillary vein. 3. Basilic vein. 4, 4. Basilic vein. 5. Point where the median basilic joins the basilic vein. 6. Posterior basilic vein. 8. Anterior basilic vein. 9. Point where the cephalic enters the axillary vein. 10. A portion of the same vein. 11. Point where, the median cephalic enters the cephalic vein. 12. Lower portion of the cephalic vein. 13. Median cephalic vein. 14. Median vein. 15. Anastomosing branch. 16. Cephalica-pollicis vein. 17. Subcutaneous veins of the fingers. 18. Subcutaneous palmar veins. 124 ANATOMY. bend of the elbow to form the basilic vein. This runs up, receiving the median basilic in an oblique direction, and pierces the deep fascia to join one of the vence. comites or the axillary vein. The radial runs up on the outside of the forearm from the back of the thumb and index finger. Receiving obliquely the median cephalic at the bend of the elbow, it becomes the cephalic vein. This runs outside of the biceps muscle to the upper third of the arm ; then passes between the pectoralis major and deltoid mus- cles, to end in the axillary vein below the clavicle. The median vein runs up from the palm of the hand, near the middle of the forearm, to divide at the bend of the elbow into the median cephalic and the median basilic ; of which, as said above, the one joins the cephalic and the other the basilic vein. Branches of the external cutaneous nerve pass behind the median cephalic, and filaments of the same nerve pass both behind and in front of the median basilic vein. Veins of the Thorax. The axillary vein, the continuation of the basilic, increasing in size in the axilla by the supply of the vence comites of the arteries of the arm, becomes the subclavian vein under the clavicle at the margin of the first rib. The subclavian vein, at the inner end of the sterno-clavicular junction, unites with the internal jugular to form the vena inno- minata. The subclavian receives as branches the external, anterior, and internal jugular veins. It is separated from the subclavian artery by the scalenus anticus muscle. The right vena innominata is about an inch and a half long. It goes almost directly downwards, to join the left vena innominata to form the descending vena cava, just below the cartilage of the first rib. It is external to, and nearer the surface than the arteria innominata. At the angle of junction of this vein and the sub- clavian, enters the vertebral vein. Lower down it receives the internal mammary, inferior thyroid, and superior intercostal veins. The left vena innominata is longer and larger than the right. It passes obliquely across the upper anterior part of the cavity of the chest, to joint the right in forming the vena cava. The vena cava descendens is a large trunk, two and a half to three inches long, vertical in its direction, entering the pericardium an inch and a half above the heart, and then emptying into the upper part of the right auricle. The right and left azygos veins, of which the right is the larger, connect the descending and ascending venae cavse. The right azygos receives nine or ten lower intercostal veins, the right bron- chial, and other veins. The left lower azygos receives four or five lower intercostal and a few other small veins. The left upper VEINS OP THE LOWER EXTREMITY. 125 azygos receives the upper intercostal veins except the superior intercostal. The left bronchial vein empties into the left superior intercostal. The bronchial veins carry back the blood from the tissue of the lungs. Spinal Veins. These form venous plexuses, as follows : dorsi-spinal veins, out- side of the spinal column ; meningo-rachidifin veins, within the canal, outside of the membranes of the cord ; venae, basis verte- brarum, of the bodies of the vertebrae ; medulli-spinal, or the veins of the spinal cord. Those of the first set, in the intervals between the vertebrae terminate, in the neck, in the vertebral veins ; in the chest, in the intercostals ; in the lumbar region in the lumbar and sacral veins. Of the second set, there are two plexuses, the anterior and the posterior longitudinal spinal veins. The terminating connections are like those of the first set. The veins of the third set join the transverse trunks which con- vert the anterior longitudinal spinal veins of the two sides. Those of the fourth set unite with the other veins of the spinal canal. Veins of the Lower Extremity. These are superficial and deep ; the latter being the vense comites of the arteries. The superficial veins of the lower extremity are the long internal saphenous, and the short external saphenous vein. The internal saphenous vein ascends, from a plexus of small veins on the back and inner side of the foot, in front of the inner malleolus, up the inside of the leg, behind the inner margin of the tibia. Going backwards gradually, at the knee it is behind the internal condyle of the femur; thence it passes up the inside of the thigh to the saphenous opening, where it penetrates the facia lata and ends in the femoral vein, an inch and a half below Pou- part's ligament. At the saphenous opening it receives the superfi- cial epigastric, superficial circumflex iliac, and external pudic veins. Its other branches are cutaneous. The internal saphenous nerve accompanies it. The external saphenous vein ascends, from a plexus on the back and outer side of the foot, behind the outer malleolus, outside of the tendo Achillis, and then across it, to the middle of the back of the leg. Passing upwards, it penetrates the fascia in the lower part of the popliteal region, and ends in the popliteal vein, between the heads of the gastrocnemius muscle. The external saphenous nerve accompanies it. The arteries of the leg are attended by venue comites or deep 11* 126 ANATOMY. veins. These are supplied, par- ticularly, by the external and in- ternal plantar, and the peroneal veins. The popliteal vein is formed by the union of the anterior and posterior tibial venae comites. Passing up through the popli- teal space to the opening in the tendon of the adductor magnus muscle, it becomes the femoral vein. Below, it is on the inner side of the artery; then it lies between it and the integument ; above, it is outside of it. The femoral vein runs with the femoral artery. Below, it is out- side of it; then, behind it ; near Fo apart 'a ligament, it is on the inner side of it. Its principal branch is the profunda femoris. The external iliac vein is the continuation of the femoral, above the crural arch. Going along the margin of the pelvis it unites, near the sacro-iliac symphysis, with the internal iliac to form the common iliac vein. The internal iliac vein is sup- plied by the vence comites of the branches of the internal iliac artery. Besides other branches, important ones are those of the hemorrhoidalund vesico-prostatic, and, in the female, uterine and vaginal plexuses. The hemor- rhoidal plexus surrounds the lower end of the rectum. The vena dorsalis penis is a large vein which returns the blood of the penis, along its back, to the prostatic plexus. The two common iliac veins unite, opposite the space between the fourth and fifth lumbar vertebra, to form the ascending vena cava. The right common iliac is shorter and more nearly vertical in its course than the left. The inferior or ascending vena cava lies upon the spinal column to the right of the aorta. Passing through a groove in the pos- SUPKRFICIAL VEINS OF THE LEGS. 1. Sa- pheua major. 2. Collateral branch. 3. Anastomosis of veins. 4. Internal saphe- na. a. Origin of the saphena vein. 6. Anastomosing branch. 7. Branches on the back of the leg. 8. The great internal vein, of the foot. 9. Arch of veins on the meta- tarsal bones. 10. Branch from the heel. 11. Branches on the sole of the foot. PORTAL SYSTEM PULMONARY VEINS. 127 terior border of the liver, it penetrates the tendon of the dia- phragm, and enters the pericardium, covered by its serous lining, to empty into the lower and posterior part of the right auricle. Branches of the ascending vena cava are the lumbar, right sper- matic, renal, supra-renal, phrenic, and hepatic veins. The lumbar veins are three or four in number. The spermatic veins come, along the spermatic cords, from the testes. The left spermatic empties into the renal. The ovarian veins in the female correspond with them. The renal veins are large ; the left is longer than the right renal. The hepatic veins, three in number, one from the right lobe, one from the left, and one from the middle of the liver, bring the blood from its substance, supplied by the portal vein and hepatic artery. Portal System. This is composed of four large veins, collecting blood from the digestive organs, and joining to make the vena portce, which en- ters and ramifies within the liver. The four veins are the superior and inferior mesenteric, the splenic, and the gastric veins. The superior mesenteric is supplied from the small intestines, caecum, and transverse colon. The inferior mesenteric receives its branches from the descend- ing colon, sigmoid flexure, and rectum. It empties into the splenic vein. By anastomoses of its hemorrhoidal branches with the branches of the internal iliac, the portal system and the general venous circulation are connected. The splenic vein receives the blood of five or six venous trunks from the spleen, and, also, the vasa brevia from the stomach, the left gastro-epiploic vein, pancreatic, pancreatico-duodenal, and inferior mesenteric veins. The gastric vein is small, accompanying the gastric artery along the upper curvature of the stomach. The portal vein, from the junction of the splenic and superior mesenteric, in front of the vena cava, behind the pancreas, goes up to the transverse fissure of the liver. Enlarged there into a sinus, it divides into two trunks, which ramify through the substance of the liver, communicating with the branches of the hepatic artery. The portal vein is about four inches in length. Pulmonary Veins. These are four, two for each lung, returning blood from the ca- pillaries around the air cells. They have no valves, are but little larger than the pulmonary arterial trunks, and carry arterial blood. There is a venous trunk for each pulmonary lobe; making three for the right lung and two for the left The pulmonary veins empty into the left auricle of the heart. 128 ANATOMY. Cardiac Veins. The blood from the heart's substance is returned by the great, anterior and posterior cardiac veins, and the venae Thebesii. The great cardiac and posterior cardiac make the coronary sinus, which lies in the posterior part of the left auriculo-ventricular groove, and empties into the right auricle. The anterior cardiac and the vence Thebesii open into the right auricle directly. The coronary sinus receives also a small oblique vein from the left auricle, the remainder of a trunk of the fcetal circulation. LYMPHATICS. These are delicate vessels with three coats, almost transparent, constricted at intervals so as to have a beaded appearance, passing Fig. 59. LYMPHATICS OF THE JEJUNUM AND MESENTERY, INJECTED: THE ARTERIES ARE At so INJKCTED. 1. Section of the jejunum. 2. Section of the mesentery. 3. Branch of the superior mesenteric artery. 4. Branch of the superior meseuteric vein. 5. Mesenteric glands receiving the lymphatics of this intestine. through numerous lymphatic glands, to combine and empty at last into the left or greater, or into the right or lesser thoracic duct. All organs have lymphatics except the brain, spinal cord, eyeball, cartilages, tendons, nails, hair, cuticle, umbilical cord, placenta, and membranes of the ovum. Lymphatic glands are most numerous in the neck, axilla, groin, and abdomen. The lymphatic vessels of the small intestine are called lactenls, from the milky character of the chyle which they absorb. The glands which they pass through are the mesenteric glands. Left Thoracic Duct. This principal trunk receives most of the lymphatics and all the lacteals. It extends from the second lumbar vertebra to near the THE SKIN. 129 neck. Its beginning is the receptaculum chyli; which lies behind and to the right of the aorta. The thoracic duct passes up through the aortic foramen in the diaphragm, goes up to the left behind the arch of the aorta, near the oesophagus ; then near the seventh cervical vertebra it curves downwards, to end at the angle of union of the left internal jugular and the subclavian veins. It has numerous valves. Its diameter is not uniform, but is about that of a small quill. Right Thoracic Duct. This is but an inch or so in length. It receives lymphatics from the right side of the head, neck, chest, right upper extremity, right Fig. 60. FEMORAL ILIAC AND AORTIC LYMPHATIC VESSELS AND GLANDS. 1. Saphenamagna vein. 2. External iliac artery and vein. 3. Primitive iliac artery and vein. 4. Aorta. 5. As- cending vena cava. 6, 7. Lymphatics. 8. Lower set of inguinal lymphatic glands. 9. Superior set of inguinal lymphatic glands. 10. Chain of lymphatics. 11. Lymphatics which accompany the circumflex iliac vessels. 12. Lumbar and aortic lymphatics. 13. Origin of the thoracic duct. 14. Thoracic duct at its commencement. lung, right side of the heart, and upper surface of the liver. It ends in the angle of junction between the right internal jugular and right subclavian veins. 130 ANATOMY. CHAPTER VII. THE SKIN. THE skin consists of two layers ; the cutis vera, derma, chorion, or true skin, and the cuticle, epidermis or scarf-skin. The cutis vera may be described as composed of the deep layer or corium, formed of fibro-connective (white fibrous and yellow elastic) tissue, and the papillary layer. The latter consists of numerous small conical eminences or pa- pillce, jj^th of an inch in length and ^|^ of an inch in diameter. Every fibre has an elongated nucleus, visible by aid of the microscope. The striped muscle exists in all the voluntary muscles; in those also of the larynx, pharynx, upper half of the oesophagus, heart, and largest of the veins. Unstriped muscular tissue is found throughout the alimentary canal, in the trachea and bronchial tubes, gall-bladder, bile-duct and other gland-ducts, calyces and pelvis of the kidney, uterus, bladder and urethra, iris, ciliary muscle, skin, all arteries, lympha- tics and veins. In the male, it is also present in the scrotum, epididymis, vas deferens, vesiculse seminales, and prostate gland. In the female, in the uterus, Fallopian tubes, broad ligaments, and vagina. Also, in the corpora cavernosa, of the penis in the male, and of the clitoris in the female. The voluntary muscles vary much in form. Each is enveloped in its sheath, and terminates at one or both ends, or, as in the dia- phragm, at its centre, in a white fibrous tendon. The tendon may be of any shape, but is most generally a rounded cord. All mus- cles are well supplied with nerves and bloodvessels. Aponeuroses are fibrous membranes, pearly white, connected with muscles and also with bones, cartilages, ligaments, &c. 12 134 ANATOMY. Fascia are nponeurotic layers of various thickness, inclosing and protecting as well as retaining in their places the organs in all parts of the body. They are divisible chiefly into the super- ficial and the deep fascia3. The superficial fascia extends under the integument over the whole body. The deep fascia is more immediately connected with the mus- cles ; giving a sheath to each of them, and also sheaths to the nerves and bloodvessels. MUSCLES OP THE HEAD AND FACE. Occipito-frontalis. Origin, from the occiput, by two flat bellies ; course, over the cranium ; on the frontal bone are formed two other flat bellies, one on each side ; insertion, into the nasal bones, and os frontis near them, and into the upper edge of the corrugator supercilii and orbicularis oculi muscles. Action, to raise or de- press the eyebrows and skin of the forehead ; sometimes that of the occiput. Attollens aurem, Attrahens aurem, Retrahens aurem. Three small rudimentary or imperfectly developed muscles, seldom capable of use in man. They are immediately under the skin ; the attollens above the ear, the attrahens above and in front of it, the retrahens behind and below it. The first two originate in the occipito- frontalis muscle; the third, in the mastoid process of the temporal bone. The first, in action, would raise the ear ; the second would draw it forward ; the third would draw it backward. The muscles of the tympanum will be described with the organ of hearing. Corrugator supercilii. Origin, internal angular process of the os frontis. Course, obliquely upwards and outwards for a short distance. Insertion, the junction of the occipito-frontalis and orbicularis oculi muscles. Action, frowning. Orbicularis oculi. Origin, upper end of nasal process of superior maxillary bone, internal angular process of frontal bone, and upper margin of palpebral ligament. Course, entirely around the eye or edge of the orbit. Action, to close the eyelids. Levator palpebrce superior is. Oiigin, upper and back part of the orbit of the eye. Course, forward over the eyeball, widening as it goes. Insertion, the upper eyelid. Action, to raise the lid and open the eye. Tensor tarsi, or Homer's muscle. Origin, os nnguis. Course, forwards a quarter of an inch, when it bifurcates. Insertions, one branch into each lachrymal duct. Action, to dilate the lachrymal ducts, and keep the lids close upon the eyeball. Muscles of the Eyeball Rectus superior. Origin, upper part of optic foramen in the rear of the orbit, and inner margin of sphe- MUSCLES OF THE HEAD AND FACE. 135 Fig. 63. MUSCLES FRONT VIEW. Ou the right half, the superficial muscles. Left half, deep-seated muscles. noidal fissure. Course, forward. Insertion, upper part of the eyeball, a little behind the cornea. Action, to raise the eye. liectas inferior. Origin, from the lower margin of optic fora- 136 ANATOMY. men; by the ligament of Zinn, a tendinous beginning for it and the internal and external recti muscles. Course, forwards. In- sertion, lower part of eyeball behind the cornea. Action, to depress the eye. Rectus internus. Origin, ligament of Zinn, and sheath of the optic nerve (with which the other recti muscles also have some connection). Course, forwards. Insertion, eyeball behind the cornea. Action, to draw the eye inwards towards the nose. Rectus externus. Origin, by two heads, one from the common ligament or tendon of Zinn, the other from the margin of the optic foramen. Between these two heads pass the third and sixth nerves and the nasal nerve. Course, forwards. Action, to draw the eye outwards. Obliquus superior or Troclilearis. Origin, margin of optic fora- men and sheath of nerve. Course, forwards to the trochlea or pulley-like process near the internal angle of the os frontis through which its round tendon passes, thence turning downwards and backwards. Insertion, sclerotic coat near the entrance of the optic nerve. Action, to roll the eye downwards and outwards. It is sometimes called musculous patheticus. Obliquus inferior. Origin, inner margin of upper maxillary bone. Course, beneath the rectus inferior, outwards and some- what backwards. Insertion, outer and posterior part of eyeball. Action, to roll the eye obliquely inwards and downwards. Pyramidalis nasi. Origin, lower margin of occipito-frontalis. Course, downwards. Insertion, upper edge of compressor nan's muscle. Action, to draw down the skin of the forehead, or draw up that of the nose. Compressor naris. Origin, root of ala nasi on one side. Course, across the dorsum of the nose. Insertion, into the corresponding muscle of the other side. Action, to compress the nostril. Levatorlabii superioris alseque nasi. Origin, by two slips, from nasal and orbitar processes of upper maxillary bone. Course, downwards. Insertions, one slip into the upper lip, the other into the ala or wing of the nose. Action, to raise the upper lip and dilate the nostril. Depressor labii superioris alseque nasi. Origin, alveoli of front teeth. Course, upwards. Insertion, upper lip and ala nasi. Action, to draw down the upper lip and the nose. Levator anguli oris. Origin, upper maxillary bone under the orbit of the eye. Course, downwards and inwards. Insertion, angle of the mouth. Action, to raise the corner of the mouth. Zygomaticus major, and Zygomaticus minor. Origin, malar port of zygoma. Course, downwards and forwards. Insertion, angle of mouth and upper lip. Action, to raise and draw out the corner of the mouth. MUSCLES OF THE HEAD AND PACE. 137 Orbicularis oris. A circular muscle, surrounding the mouth, in the lips. Action, to close the mouth. Depressor anguli oris. Origin, base of lower jaw at the side of the chin. Course, obliquely, some fibres vertically, upward to an apex. Insertion, corner of the mouth. Action, to draw down the corner of the mouth. Depressor labii inferioris. Origin, base of lower jaw at the side of the chin. Course, upwards and inwards. Insertion, the lower lip. Action, to draw the lower lip downwards. Levator menti. Origin, alveoli of front teeth of the lower jaw. Course, downwards and forwards. Insertion, lower lip and contig- uous tegument. Action, to raise the chin and lower lip. Buccinator. Origin, ridge between the last molar tooth and the coronoid process of the lower jaw and upper jaw between the last molar and the pterygoid process of the sphenoid bone. Course, horizontally forwards. Insertion, the corner of the mouth. Action, to draw the corner of the mouth backwards or outwards. Masseter. Origin, by an outer layer, from the tuberosity of the upper jaw-bone, the lower edge of the malar bone and the zygoma; by an inner layer, from the posterior surface of the zygoma. Course, outer layer, downwards and backwards; inner layer, downwards and forwards. Insertion; outer plane, raraus and angle of the lower jaw; inner plane, coronoid process of the same bone. Action, to draw up the lower jaw. The outer plane or layer acting alone, protrudes the jaw; the inner alone, draws it backwards. Temporalis. Origin, the side of the head from the lower part of the parietal bone to the zygoma, Course, downwards and somewhat forwards. Insertion, tendinous, passing under the zygoma, into the coronoid process of the lower jaw. Pterygoideus internus. Origin, fossa formed by the internal face of the pterygoid process of the sphenoid and palate bones. Course, downwards and outwards. Insertion, inner face of the'' angle of the lower jaw. Action, to close the jaw, or, if one acts at a time, to give it a lateral grinding motion Pterygoideus externus. Origin, outside of the pterygoid process of the sphenoid bone, and its spinous and temporal processes. Course, outwards and a little backwards. Insertion, neck of the lower jaw. Action, to draw the lower jaw forwards ; or, when the two act alternately, to produce an oblique or grinding motion. Hyo-glossus, Origin, hyoid bone. Course, upwards and out- wards. Insertion, side of the tongue. Action, to depress the side of the tongue, making its dorsum convex. Genio-hyo-glossus. Origin, back of the chin. Course, fan-like, backwards, to the middle of the tongue and hyoid bone. Insertion, the whole length of the tongue, and the base of the hyoid bone. Action, according to the fibres of it engaged, to draw the tongue 12* 138 ANATOMY. forwards, backwards or downwards ; or, to draw the os hyoides forwards and upwards. Stylo- ylossus. Origin, styloid process of the temporal bone. Course, in slender rounded mass, downwards and forwards. Inser- tion, root and side of the tongue. Action, to draw the tongue backwards and sideways. Lingualis. Origin, the side of the root of the tongue. Course, forwards, between the hyo-glossus and the genio-hyo-glossus. Insertion, apex of the tongue. Action, to raise the apex of the tongue, shorten it and curve it backwards. Other muscles of the substance of the tongue will be described hereafter with it. Circumflexus palati. Origin, spinons process of sphenoid bone, Eustachian tube, and internal pterygoid process of sphenoid. Course, over the hook of the internal plate of the pterygoid process as a pulley, after which it widens. Insertion, velurn palati (soft palate), and edge of palate bones. Action, to extend the velum palati. Levator palati. Origin, apex of petrous portion of temporal bone, and Eustachian tube. Course, downwards, forwards and inwards. Insertion, into the soft palate as far as the uvula. Action, to raise the soft palate and draw it backwards. Constrictor isthmi faucium Origin, side of the tongue near its roots. Course, upwards between the folds of the anterior half arch of the palate. Insertion, soft palate at the base of the uvula. Action, to bring the tongue and palate together, and close the opening from the mouth into the pharynx. Palato-pharyngeus. Origin, posterior half arch of the palate. Course, downwards, in a curve, the convexity outwards. Insertion, upper and back edge of the thyroid cartilage, and the pharynx between its middle and lower constrictor muscles. Action, to depress the palate and force it down over the pharynx. Azygos uvulce. Origin, spinous process of the palatal suture. Course, downwards. Insertion, the whole length of the uvula. Action, to contract the uvula and draw it upwards. MUSCLES OF THE NECK. Platysma myoides. Origin, connective tissue below the clavi- cle. Course, flat and thin (with pale and imperfectly developed fibres), upwards under the skin of the front and side of the neck. Insertion, the side of the lower jaw and skin of the face. Action, rudimentary or almost null in man; in the ox, horse, &c., as the cutaneous muscle, to shake forcibly the skin of the neck. If it act in man, it must draw down the jaw or lower lip, or raise the bkin of the neck. SternO'chido-mastoideus. Origin, upper end of sternum, and sternal end of clavicle. Course, by two separate heads, at first, MUSCLES; OF THE NECK. 139 which, not far above the clavicle, join into one muscle, to pass obliquely upwards and outwards. Insertion, mastoid process of the temporal bone. Action, if only one contracts, to draw the head down to one side ; if both act together, to 4 draw the head down toward the chest. Digastricus. Origin, the mastoid process. Course, first fleshy, downwards and forwards, then tendinous through a perforation in thestylo-hyoideus muscle, then fleshy again, upwards and forwards. Insertion, base of lower jaw at its median line or symphysis. Action, to draw the jaw down and open the mouth ; or, to raise the hyoid bone and throat. Stylo-hyoideus. Origin, styloid process of temporal bone. Course, downwards and forwards, perforated by the digastricus. Insertion, os hyoides. Action, to raise the hyoid bone and draw it backwards. Mylo-hyoideus. Origin, broad and thin from inside of lower jaw, from the middle of the chin to the last molar tooth. Course, downwards and forwards. Insertion, os hyoides. Action, to draw the os hyoides upwards and forwards, and protrude the tongue. It forms the floor of the mouth. Genio-hyoideus. Origin, tubercle inside of lower jaw near its middle line. Course, downwards and backwards. Insertion, os hyoides. Action, to raise the hyoid bone and draw it forwards. OmO'hyoideus. Origin, upper margin of scapula. Course, ob- liquely upwards and forwards, as along, slender muscle, tendinous where it passes under the sterno-cleido-mastoid. Insertion, os hyoides. Action, to draw down the hyoid bone, or draw it to one side. Sterno-hyoideus. Origin, first bone of the sternum, part of clavicle, and cartilage of first rib. Course, upwards. Insertion, os hyoides. Action, to draw down the hyoid bone. Sterno-thyroideus. Origin, margin of first bone of sternum, and cartilage of first- rib. Course, upwards on the front and side of the trachea and thyroid gland. Insertion, lower edge of the thyroid cartilage. Action, to draw the larynx downwards. Thyro-hyoideus. Origin, side of thyroid cartilage. Course, upwards. Insertion, base and corner of os hyoides. Action, to approximate the thyroid cartilage and hyoid bone. Constrictor pharyngis inferior. Origin, sides of thyroid and cricoid cartilages of the larynx. Course, superior fibres, obliquely upwards, covering part of the constrictor medius ; inferior fibres, horizontally, over the upper part of the oesophagus. Insertion, meeting its fellow of the opposite side at the median line of the back of the pharynx. Action, to constrict the lower portion of the pharynx and draw it upwards and backwards. Constrictor pharyngis medius. Origin, corner of os hyoides and ligament between it and the thyroid cartilage. Course, 140 ANATOMY. spreading, and dividing into two terminal portions. Insertion, into its fellow at the back of the pharynx, and into the cuneiform process of the occiput, before the foramen magnum. Action, to constrict the middle of the pharynx, and to draw the hyoid bone upwards and backwards. Constrictor pharyngis superior. Origin, cuneiform process of occiput, pterygoid process of sphenoid bone, and upper and lower jaws near the last molar tooth ; also, the buccinator muscle, palate, and root of the tongue. Course, almost horizontal, its lower edge covered by the constrictor medius. Insertion, meeting its fellow at the median line of the pharynx behind. Action, to constrict the upper portion of the pharynx. Stylo-pharyngeus. Origin, styloid process. Course, downwards and forwards. Insertion, the side of the pharynx between the upper and middle constrictors, and into the posterior edge of thyroid cartilage. Action, to raise the pharynx and larynx, and open the pharynx above. The muscles belonging to the larynx itself have been described in the account of it as a part of the apparatus of respiration. Longus colli. Origin, sides of the bodies of the three upper dorsal vertebras, and transverse processes of four lower cervical ver- tebras. Course, upwards and slightly forwards. Insertion, front of bodies of all the vertebrae of the neck. Action, to bend the neck forwards or to one side. Rectus capitis anticus major. Origin, transverse processes of third, fourth, fifth and sixth vertebras of the neck. Course, np- wards and a little inwards. Insertion, cuneiform process of occiput, in front of condyle. Action, to depress the head. Rectus capitis anticus minor. Origin, front of the atlas Course, upwards. Insertion, occiput in front of condyle. Action, to depress or bow the head. Rectus capitis posticus major. Origin, spinous process to the second cervical (axis or dentata) vetrebra. Course, obliquely upwards, widening as it ascends. Insertion, inferior semicircular ridge of the occiput. Action, to draw back or rotate the head. Rectus capitis posticus minor. Origin, posterior tubercle of the atlas vertebra. Course, obliquely upwards, widening as it as- cends. This muscle is within the last described, the two minores being thus between the two majores. Insertion, occiput, along part of the semicircular ridge and the space between it and the foramen magnum. Action, to draw the head backwards. Obliquus capitis inferior. Origin, spinous process of vertebra dentata. Course, upwards and outwards. Insertion, transverse process of atlas. Action, to rotate the atlas, and head upon it, on the axis. Obliqnus capitis superior. Origin, transverse process of the atlas. Coarse, upwards and slightly inwards. Insertion, outer MUSCLES OF THE NECK. 141 end of the lower semicircular ridge of the occiput. Action, to draw the head backwards. Rectus capitis lateralis. Origin, transverse process of the atlas. Course, obliquely upwards. Insertion, occiput outside of the cou- dyle. Action, to draw the head to one side. Fig. 64. MHSOLES BACK VIEW. The fascia is left upon the left limbs, removed from the right.' 142 ANATOMY. Scalenus anticus. Origin, first rib near its cartilage. Course, upwards, inwards, and backwards. Insertion, transverse processes of the fourth, fifth, and sixth vertebras of the neck, by three separate tendons. Action, to draw the neck to one side, or lift the first rib. Scalenus medius. Origin, first rib, upper andouter part. Course, upwards, inwards, and backwards; separated from the scalenus anticus below by the subclavian artery, above by the cervical nerves. Insertion, by separate tendons, into the transverse processes of all the cervical vertebrae. Action, to draw the ueck to one side, or lift the rib. Scalenus posticus. Origin, second rib near its tubercle. Course, upwards, inwards, and backwards. Insertion, transverse processes of fifth and sixth cervical vertebra. Action, like that of the two preceding muscles. Trapezius. Origin, occipital protuberance, spinous processes of five first vertebrae of the neck, by the ligamentum nucha?, and spinous processes of two last cervical and all the dorsal vertebra?. Course, by converging fibre's, some downwards, some horizontally, and others upwards, the whole outwards. * Insertion, outer half of the clavicle, the acromion process, and whole length of spine of the scapula. Action, according to its partial or total contraction, to draw the shoulder upwards, backwards, or downwards; or, if the upper portion act when the shoulder is fixed, to draw the head to one side. This muscle is just beneath the skin, covering the other dorso-cervical muscles. - Rhomboideus major. Origin, spinous processes of the last cer- vical and first four dorsal vertebrae. Course, downwards and out- wards. Insertion, the whole base of the scapula, below its spine. Action, to draw the scapula upwards and backwards. Rhomboideus minor. Origin, spinous processes of three lower cervical vertebras. Course, obliquely downwards and outwards. Insertion, base of the scapula opposite its spiue. Action, same as that of rhomboideus major. Levator scapulae. Origin, from transverse processes of four or five upper cervical vertebra?, by distinct tendons. Course, down- wards and outwards. Insertion, base of the scapula above the spine. Action, to raise the scapula. Cervicalis descendens. Origin, upper margin of first four ribs, by as many tendons. Course, upwards and inwards. Insertion, transverse processes of fourth, fifth, and sixth cervical vertebrae. Action, to draw the neck backwards. Splenius. Origin, spinous processes of the five lower cervical and four upper dorsal vertebrae. Course, upwards and outwards. Insertion, into transverse processes of three or four cervical ver- tebrae ; and also, into the mastoid process and occiput. Complexus. Origin, four lower cervical and seven upper dorsal vertebra?, and spinous process of first dorsal. Course, upwards. MUSCLES OP THE TRUNK. 143 Insertion, on the inner side of splenius, into the occiput, between the upper and lower semicircular ridges. Action, to draw the head backwards or to one side. Trachelo-mastoideus. Origin, transverse processes of five lower cervical and three upper dorsal vertebrae. . Course, upwards and outward. Insertion, *nastoid process. Action, same as that of the complexus. MUSCLES OF THE TRUNK. Pectoralis major. Origin, sternal half of clavicle, whole length of upper and middle bones of the sternum, and cartilages of fifth Fig. 65. SUPERIOR MUSCLES OF THE UPPER FRONT OF TOE TRUNK. 1. Sterno-hyoid. 2. Sterno- cleido-rnastoid. 3. Sterno-lhyroid. 4. Sterno-cleido-mastoid. 5. Edge of the trapezius. 6. Clavicle. 7. Clavicular origin of the pectoralis major. 8. Deltoid. 9 Fold of pecto- ral is major on the anterior edge of the axilla. 10. Middle of the pectoralis major. 11. Crossing and interlocking of fibres of the external oblique of one sitie with those of the other. 12. Biceps flexor cubiti. 13. Teres major. 14. Serratus major anticus. 15. Su- perior heads of external oblique interlocking with serratus major. and sixth ribs. Course, outwards, converging, and downwards to the axilla. Insertion, by a flat, broad, twisted tendon, into the humerus, in front of the bicipital groove. Action, to draw the 144 ANATOMY. arm inwards and forwards, or downwards if raised. This muscle lies under the skin. Pectoralis minor. Origin, third, fourth, and fifth ribs near their cartilages. Course, upwards and outwards, converging; it lies beneath the pectoral is major. Insertion, coracoid process of the scapula. Action, to depress the shoulder ; or, to raise the ribs. Subclavius. Origin, cartilage of the first rib. Course, out- wards, under the clavicle. Insertion, under margin of the clavicle almost its whole length. Action, to draw the clavicle downwards. Serratus magnus, vel anticus. Origin, by tooth-like digitations, from the first nine ribs. Course, upwards and backwards, in front of and beneath the subscapularis. Insertion, whole length of the base of the scapula. Action, to draw the scapula forwards and downwards, or to raise the ribs. Intercostales, externi et interni. Origin, lower margin of each rib except the last. Course, oblique ; the fibres of the external intercostals going downwards and forwards, those of the internal downwards and backwards, so as to cross each other. Insertion, upper edge of each rib except the first. Action, to elevate the ribs. Between the two layers or sets of muscles pass the inter- costal vessels and nerves. In contact with their inner surface is the pleura. Sterno-costalis. Origin, middle and last piece of the sternum. Course, upwards and outwards. Insertion, cartilages of third, fourth and fifth, and sometimes sixth ribs. Action, to draw down the ribs and diminish the cavity of the chest. Levatores costarum. Origin, transverse processes of the last cervical and eleven upper dorsal vertebras. Course, downwards and outwards, twelve in number on each side. Insertions, into the rough surfaces of the ribs between their tubercles and angles. Action, to elevate the ribs. Diaphragma major. Origin, by fleshy slips from the ensiform cartilage of the sternum, and from the inner face of the cartilages of the last six ribs. Course, converging, by all its fibres, to a broad central tendon. Insertion, into the cordiform tendon, which is notched in shape at the vertebral column, and pointed near the sternum. Through the foramen quadratum, near the spine, the vena cava ascends. Diaphragma minor. Origin, by four pairs of fleshy and ten- dinous slips, of which the longest arise from the third and fourth lumbar vertebra?. The second pair come from the ligament be- tween the second and third lumbar vertebras. The third pair from the sides of the second, and the fourth pair from the base of the transverse process of the same vertebra. Course, by muscular bands, upwards, in two columns, one on each side. Insertion, into the back and notch of the cordiform tendon. Through this muscle, the lesser diaphragm, pass through one foramen (oesopha- MUSCLES OF THE TRUNK. 145 geum), the oesophagus and pnenmogastric nerve ; through another (hiatus aorticus) the aorta, thoracic duct, and great splanchnic nerve. Action, that of the greater and lesser diaphragm, often described and generally named as one muscle, is, by descending in its contraction, to increase the cavity of the chest in inspiration. The diaphragm is also a septum or partition between the chest and the abdomen. Obliquus externus abdominis. Origin, by digitations from the last eight ribs, near their cartilages; in apposition to portions of the pectoralis major, serratus magnus, and latissimus dorsi. Course, downwards and inwards over the abdomen ; a few fibres crossing the median line just above the pubes. This muscle is next beneath the skin and superficial fascia. Insertion, into the median line or linea alba, where it meets its fellow ; into the anterior half of the crest of the ilium; anterior superior spine of the ilium, and pubes at and near the symphysis. The tendinous cord which reaches from the spine of the ilium to the pubes is called PouparVs liga- ment. This divides into two bands anteriorly, one passing to the symphysis and the other to the spine of the pubes. The latter is reflected outwards and backwards along the linea ileo-pectinea for about an inch ; the reflection being called in surgical anatomy Gimbernafs ligament. Action, to sustain and compress all the contents of the abdomen and force them upwards towards the diaphragm, or downwards towards the perineum. Obliquus internus, vel Ascendens abdominis. Origin, posterior face of sacrum, spinous processes of three lower lumbar vertebrae, crista of the ilium, and Poupart's ligament. Course, upwards and inwards to the linea semilunaris, where the tendon separates into an anterior and posterior layer. The former joins the tendon of the obliquus externus and passes in front of the rectus muscle to the linea alba. The posterior layer joins the tendon of the trans- versalis muscle to go behind the rectus ; except that, from about, half way between the umbilicus and the pubes downwards, it passes with the anterior portion in front of the rectus muscle. Insertion, into the six lower ribs at their cartilages, the side of the ensiform cartilage, and the linea alba or median vertical tendinous line of the abdominal superficies. Action, the same as that of the external oblique. Transversalis abdominis. Origin, cartilages of six or seven lower ribs, transverse processes of the last dorsal and upper four lumbar vertebrae, almost the whole length of the crest of the ilium, and anterior half of Poupart's ligament. Course, across the front of the abdomen. Insertion, into the whole length of the linea alba. Action, like that of the last two muscles. Rectus abdominis. Origin, anterior face of ensiform cartilage, and cartilages of the fifth, sixth, and seventh ribs. Course, down- wards on each side of the linea alba, in a flat band about three 13 146 ANATOMY. Fig. 66. inches in width, narrowing below and becoming tendinous. Inser- tion, the pubes, at and near the symphysis. Action, to compress the contents of the abdomen, or to bend the body or raise the ante- rior part of the pelvis. The tinea semilunaris is a white curved line, with the convexity outwards, extending, on each side, downwards from the cartilage of the eighth rib to the pubes. It is formed by the tendon of the internal oblique muscle at its division. The linea transverse? are three or four tendinous lines crossing the rectus muscle at right angles to the direction of its fibres at the distance of a few inches from each other. The anatomy of hernia will be given by itself hereafter. Pyramidalis. This muscle is often absent. Origin, upper margin of the pubes. Course, upwards, in a pyramidal form, within the sheath of the rectus. Insertion, the linea alba and inner edge of the rectus. Action, to make tense the rectus muscle, and support the lower part of the abdomen. Quadratus lumborum. Ori- gin, posterior and upper margin of ilium, for two inches from the spine. Course, upwards and in- wards. Insertion, into the trans- verse processes of all the lumbar and the side of the last dorsal vertebrae, and into the last rib near the spine. Action, to move the loins to either side, or if both act, to move the pelvis forward. It may also depress the last rib. Psoasmagnus. Origin, bodies and transverse processes of the last dorsal and all the lumbar vertebrae. Course, in an oblong form downwards and forwards, under or behind Poupart's liga- ment and over the pubes. The peritoneum covers it in front. Insertion, into the trochanter mi- nor, and an inch or so of the^ shaft of the femur. Action, to" LATERAL VIEW OF THE MUSCLES OF THE Turis-K. 1. Latissirnus dorsi. 2. Serratus major anticus. 3. External oblique. 4. Two external intercostal muscles. 6. Two internal intercostal muscles. 6. Transversalis abdominis. 7. Fascia lumborum. 8. Sheath of the rectus. 9. Rectus abdominis cut off. 10. Rectus abdominis of right side. 11. Crural arch. 12. Glutens magnus medius and tensor vaginae femoris covered by the fascia lata. MUSCLES OP THE TRUNK. 14? flex the thigh on the pelvis and rotate it a little outwards ; or when the thigh is fixed, to bend the body forwards. Psoas parvus. Origin, sides of last dorsal and first lumbar ver- tebrae, and intervertebral ligament. Course, along the internal side of the psoas magnus. Insertion, linea ilio-pectinea at the junction of the pubes and ilium. Action, to bend the spine upon the pelvis ; and to draw up the femoral vessels in their sheath. lliacus internus. Origin, transverse process of the last lumbar vertebra, whole inner edge of crest of the ilium, and the same bone between the anterior superior spine and the acetabnlum; also, from the whole venter or concavity of the ilium. Course, down- wards, and somewhat forwards, over the edge of the pubes behind Poupart's ligament. Insertion, with the psoas magnus into the trochanter minor of the femur. Action, to flex the thigh upon the pelvis, or the body towards the thigh. Fig. 67. ABDOMINAL MUSCLES AND INGUINAL CANAL. 1. External oblique muscle. 2. Its aponeu- rosis. 3. Its tendon slit up and turned back to show the canal. 4. Anterior superior spinous processes. 5. Poupart's ligament. 6. External column of external ring. 7. Internal column of external ring. 8. Intercrossing of the tendons of each side. 9. Body of the pubes. 10. Upper boundary of the external abdominal ring the line points to the ring. 11, 12. Fascia trausversalis. 13. Fibres of internal oblique turned up. 14. Fibres of transversalis muscle. 15. Internal fing enlarged for demonstration. 16. Sartorius. 17. Fascia lata fern oris. 18. Rectusfemoris. 19. Adductor longus. 20. Penis. 21. Fascia lata of the opposite thigh. 22. Point where the saphena vein enters the femoral. 23. Fascia lata as applied to the vessels. 24. Insertion of transversalis muscle. 25, 26. Fascia transversalis. 27. Poupart's ligament turned off from the internal muscles. 28. Transversalis abdouunis. 29. Internal oblique. 30. Rectus abdorninis. Latissimus dorsi. Origin, spinous processes of the last seven dorsal and all of the lumbar vertebrae and the sacrum; also the 148 ANATOMY. outer margin of the sacrum and posterior part of the ilium, and the last four ribs. Course, by converging fibres, upwards and horizontally outwards, towards the axilla, passing over the inferior angle of the scapula. Except above, where the trapezius covers it, this muscle lies next under the skin. Insertion, by a flat, strong tendon, into the humerus just behind the bicipital groove. Action, to draw the arm downwards and backwards, and to roll it inwards. Serratus posticus superior. Origin, from the ligamentum nucha3, over the last three cervical and two upper dorsal vertebrae. Course, obliquely downwards and outwards. Insertion, by fleshy slips, into the second, third, fourth, and fifth ribs, beyond their angles. Action, to raise the ribs. Serratus posticus inferior. Origin, lumbar fascia, and spinous processes of the last two dorsal and first three lumbar vertebroe. Course, upwards and outwards. Insertion, by. fleshy slips, into the last four ribs, near their cartilages. Inter spinales. Origin, in the cervical and lumbar regions, from the upper part of each spinous process. Course, upwards, in quadrilateral form, but of small size. Insertion, into the spinous process of the vertebra next above its origin. Action, to draw the spinous processes together, and sustain the spine in the erect position. Transver salis cervicis. Origin, transverse processes of five upper dorsal vertebrae. Course, upwards, between the splenius and the traehelo-mastoideus. Insertion, into the transverse processes of all the cervical vertebroe except the Grst and the last. Action, to draw the neck backwards or to one side. Intertransversalis Origin, each transverse process. Course, vertical. Insertion, the transverse process next above or below. Action, to bend the spine to one side. Semi-spinalis colli. Origin, transverse processes of first six dor- sal vertebrae. Course, upwards. Insertion, spinous processes of all the cervical vertebrae except the first and last. Action, to draw the neck obliquely backwards. Semi-spinalis dorsi. Origin, transverse processes of theseventh, eighth, ninth, and tenth dorsal vertebrae. Course, upwards. Inser- tion, spinous processes of last two cervical and five or six upper dorsal vertebrae. Multifidus spincB. Origin, back of the sacrum and adjacent part of crest of the ilium, from the oblique and transverse processes of all the lumbar vertebrae, and from the transverse processes of all the dorsal and the last four cervical vertebrae. Course, upwards and inwards. Insertion, last five or six cervical spinous processes, and all those of the dorsal and lumbar vertebrae. Action, to draw the spine backwards or to one side ; or, both acting, to sustain the spine in the erect position. Spinalis dorsi. Origin, spinous processes of three lower dorsal MUSCLES OP THE TRUNK. 149 and two upper lumbar vertebrae. Course, upwards. Insertion, into the spinous processes of eight or nine of the upper dorsal spinous processes, excluding the first. Action, to sustain the spine in the erect position. Longissimus dorsi. Origin, from the back of the whole sacrum, the posterior part of the crest of the ilium, and the spinous and Fig. 68. SECOND LAYER op MUSCLES OF THE BACK. 1. Trapezius. 2. A portion of the tendinous ellipse formed by the trapezius on both sides. 3. Spine of scapula. 4. Latissimus dorsi. 5. Deltoid. 6. Infra-spinatns and teres minor. 7. External oblique. 8. Gluteus medius. 0. Gluteus magnus. 10. Levator scapulae. 11. Rhomboideus minor. 12. Rhomboideus major. 13. Splenius capitis. 14. Splenius colli. 15. Portion of origin of latissimus dorsi. 16. Serratus inferior posticus. 17. Supra-spinatus. 18. Infra-spiuatus. 19. Teres minor. 20. Teres major. 21. Long head of triceps extensor cubiti. 22. Serratus major auticus. 23. Internal oblique. transverse processes of all the lumbar vertebra. Course, upwards ; filling the space between the spine and the angles of the ribs. 13* 150 ANATOMY. Insertion, into the transverse processes of all the dorsal vertebrae, and the lower edge of each rib, except the last two, near their tubercles. Action, to erect, or keep erect, the spinal column. Sacro-lumbdlis. Origin, in common with the longissimus dorsi ; and, also, by the musculi accessorii, from the last six or eight ribs, Course, obliquely upwards. Insertion, into the angles of all the ribs. Action, with the last two, to raise the trunk and to keep it erect. The three muscles are sometimes together called the erector spinaB. Levator ani. Origin, pubes near the symphysis and arch, and upper margin of thyroid foramen ; spine of the ischium, and con- nected aponeurosis. Course, by converging fibres, downwards and inwards. Insertion, last two bones of the coccyx, semi-cir- cumference of the rectum just above the sphincter ani, and the side of the prostate gland and membranous part of the urethra. Action, to form the floor of the pelvis, to dilate the anal orifice, and to retract the bowel after defecation. Coccygeus. Origin, spine of the ischium. Course, gradually expanding over the inside of the posterior sacro-ischiatic ligament, inwards and backwards. Insertion, into the whole length of the side of the os coccygis. Action, to draw forwards the coccyx, and to aid the levator ani in forming a floor to the pelvis. Sphincter ani. Origin, point of the os coccygis. Course, for- wards and around the anus just beneath the skin. Action, to close the anus. Cremaster. Origin, by an outer and inner fasciculus: the former, from Poupart's ligament ; the latter, from the spine of the pubes. Course, downwards, over the testis. Insertion, into the tunica vaginalis testis and scrotum. Action, to draw up the testis. The lower portion of this muscle is generally pale and indistinct. Erector penis. Origin, tuberosity of the ischium. Course, upwards, to surround the crus penis. Insertion, into the membrane of the corpus cavernosum. Action, to compress the corpus caver- nosum and detain blood in it during erection. Accelerator urines. Origin, ramus of the pubes and crus penis. Course, downwards ; broad and thin in form. Insertion, into the anterior median line of the bulb of the urethra, and also into the anterior margin of the sphincter ani. Action, to propel urine or semen into and along the urethra. Transversus perinei Origin, tuberosity of the ischium. Course, across the perineum. Insertion, into the anterior margin of the sphincter ani. Action, to dilate the bulbous portion of the urethra ; or, to hold it in its position. Erector clitoridis, of the female. Origin and course as in the erector penis of the male ; insertion, into the clitoris ; action, to assist in its erection. Sphincter vaginse, in the female. Origin, anterior margin of MUSCLES OP THE ARM. 151 the sphincter ani, and neighboring connective tissue. Course, around the orifice of the vagina. Insertion, into the clitoris, meet- ing its fellow of the other side. Action, to contract the external orifice of the vagina. A further account of the surgical anatomy of the perineum will be given hereafter. MUSCLES OF THE SHOULDER. Supra-spinatus. Origin, the whole fossa above the spine of the scapula, and the spine itself. Course, with a strong tendon, under the acromion process. Insertion, into the great tubercle of the hnmerns. Action, to raise the arm and turn it outwards. Infra-spinatus. Origin, spine of scapula and fossa infra- spinata. Course, with a strong tendon, under the acromion pro- cess. Insertion, into the great tubercle of the humerus, middle face. Action, to roll the humerus outwards and backwards, and to sustain it when raised. > Teres major. Origin, inferior angles of scapula. Course, upwards and outwards, with the latissimus dorsi. Insertion, by a broad tendon, into the ridge at the inner"1nargin of the bicipital groove of the humerus. Action, to draw the arm downwards and backwards, and to roll it inwards. Subscapularis. Origin, base and under surface of the scapula. Course, upwards and outwards, its fibres converging. Insertion, into the lesser tubercle of the head of the os humeri. Action, to draw down the arm and roll it inwards. Deltoides. Origin, outer third of the clavicle, acromion pro- cess, and inferior edge of spine of scapula opposite to the trape- zius muscle. Course, converging to make a covering for the shoulder, and triangularly down upon the outside of the arm to near its middle. Insertion, into a rough surface near the centre of the humerus. Action, to raise the arm, and move it either for* wards or backwards according to the fibres used. MUSCLES OF THE ARM. Coraco-lrachialis. Origin, coracoid process of the scapula. Course, downwards. Insertion, inner side of humerus near its middle. Action, to draw the arm upwards and forwards. Biceps flexor cubiti. Origin, by two heads: the longer, by a round slender tendon, from the upper margin of the glenoid cavity of the shoulder-joint ; the shorter, from the coracoid process of the scapula. Course, the two heads uniting into a thick and long muscle, downwards upon the front of the humerus. Insertion, into the tubercle at the upper and anterior part of the radius. Action, to bend the forearm upon the arm. BrachiaUs anticus. Origin, from the middle of the front part of the humerus, on each side of the insertion of the deltoid. Course, 152 ANATOMY. downwards. Insertion, into a depression at the base of the coronoid process of the ulna. Action, to flex the forearm upon the arm. Triceps extensor cubiti. Origin, by three heads. The longest comes from the scapula near the glenoid cavity. The second head, from the back part of the upper end of the humerus. The third, from the inner side of the humerus near the insertion of the teres major. Course, the three heads uniting above the middle of the humerus, downwards upon the back of the arm. Insertion, into the olecranon process, ridge of the Fig- 69. ulna, and condyles of the humerus. Action, to extend the forearm. MUSCLES OF THE FOREARM. Anterior, Superficial Layer. Pronator radii teres Origin, inter- nal condyle of os burner!, and coronoid process of ulna. Course, obliquely across the forearm. Insertion, poste- rior part of the middle of the radius. Action, to roll the radius inwards, and pronate the hand or turn the palm backwards or downwards. Flexor carpi radialis.- Origin, inner condyle of humerus, and upper front part of the ulna, between the pronator radii teres and the flexor digitorum snblimis. Course, downwards along the radius, ending in a long tendon which goes over the trapezium under the annular ligament of the wrist. Insertion, metacarpal bone of the fore- finger, in front of its upper end. Action, to bend the hand at the wrist. Pahnaris long us. Origin, inner condyle of humerus. Course, soon becoming tendinous, downwards. In- sertion, annular ligaments of the wrist, and palmar aponeurosis. Action, to aid in bending the hand, or to make tense the tegument of the palm. Flexor carpi ulnaris. Origin, inner condyle of humerus, olecranon pro- cess, and inner edge of ulna to within three or four inches of the wrist. Course, downwards. Insertion, pisi- OITTER LAYER op MUSCLES ON THE FllONT OF THE FOREARM. 1. Biceps flexor cubiti. 2. Brachialiainternus. 3 Triceps. 4. Pronator radii tores. 6. Flexor carpi radialis. 6. Palmaris longus. 7. Flexor sublimis digito- rum. 8. Flexor carpi ulnaris. 9. Palmar fascia. 10 Palmaris brevis muscle. 11. Abductor pollicis mauus. 12. Flexor brevis pollicis manus. 13. Supinator longus. 14. Extensor ossis mutacarpi pollicis. POSTEEIOE REGION. 153 form bone, and base of metacarpal of little finger. Action, to bend the hand towards the ulna. Flexor digitorum sublimis. Origin, inner condyle of humerus, coronoid process of ulna, and upper front of radius. Course, downwards ; dividing above the wrist into four bellies, each of which sends off a tendon ; all the tendons pass under the annular ligament. Insertions; each tendon is attached to the second phalanx of a finger ; being first perforated by the tendon of the flexor profundus. Action, to bend the finger at the second phalanx, and the hand on the forearm. Deep-Seated Anterior Layer. Flexor digitorum profundus. Origin, upper and outer part of ulna, coronoid process, interosseous ligament, and half way down the ulna. Course, beneath the sublimis downwards ; also, divid- ing above the wrist and giving off four tendons. Insertions, into the third phalanges of the fingers, perforating first the tendons of the sublimis. Flexor longus pollicis. Origin, front of radius below its tuber- cle, middle two-thirds of the same bone, and also from the inner condyle of the humerus. Course, downwards. Insertion, base of second' phalanx of the thumb. Action, to bend the last joint of the thumb, and aid in bending the hand. Pronator quadratus. Origin, from a ridge on the inner and under part of the ulna. Course, in quadrangular form, two inches wide, across the forearm. Insertion, into the front of the radius. Action, to pronate the forearm and hand. Posterior, Superficial Layer. Extensor digitorum communis. Origin, outer condyle of humerus, and contiguous fascia. Course, downwards, upon the. back of the forearm, dividing above the wrist into four tendons, which pass under the annular ligament in a groove of the radius. Insertions, into the whole length of the posterior faces of the fingers. Action, to extend the fingers. Extensor carpi ulnaris. Origin, external condyle of humerus, middle of ulna, and fascia. Course, downwards, ending in a round tendon which passes through a groove on the back of the ulua. Insertion, into the base of the metacarpal of the little finger. Action, to extend the hand at the wrist. Extensor minimi digiti. Origin, in common with the extensor communis digitorum. Course, downwards, its tendon going through a separate ring of the annular ligament. Insertion, with that of the tendon of the extensor communis, into the back of the little finger. Action, to extend the little finger. 154 ANATOMY. Fig- 70. Anconeus. Origin, back of the outer condyle of the humerus. Course, upper fibres, horizontally, lower ones obliquely, across the back of the forearm near the elbow. Insertion, into the olecranon and adjacent part of the ulna. Action, to aid in ex- tending the forearm or to rotate it inwards. Extensor carpi radialis longior. Origin, humerus, just^ibove the outer condyle. Course, downwards, along the back of the radius, and, by a long flat tendon, under the annular liga- ment. Insertion, metacarpal of the forefinger. Action, to extend or draw backward the wrist and hand. Supinator radii longus. Origin, the ridge of the humerus, above the outer condyle almost to the middle of the bone. Course, downwards, upon the outside of the radius. Insertion, into the radius, above its styloid process. Action, to roll out the radius, and turn the palm of the hand forwards. Extensor carpi radialis brevier. Origin, outer condyle of humerus. Course, downwards along the back of the radius. Insertion, metacarpal of the middle or second finger. Action t to extend the hand and wrist. Posterior Deep Seated Layer. Supinator radii brevis. Origin, external condyle of humerus, upper and outer part of ulnar and interosse- ous ligament. Course, obliquely downwards, over the outer edge of the radius. Insertion, upper and outer part of radius, and its tubercle. Ac- tion, to supinate the foramen and hand. Extensor major pollicis. Origin, back of ulna above its middle, interos-seous ligament, and adjacent part of radius. Course, down- wards on tlie back of the radius. Insertion, second phalanx of the thumb. Action, to extend the last bone of the thumb. OUTER LAYER OF MUSCLES ON THE BACK OF THE FOREARM. 1. Biceps Flexor. 2. Brachialis interims. 3. Triceps extensor. 4. Supinator radii longus. 5. Extensor carpi radialis longior. 6. Extensor carpi radialis brevior. 7. Tendinous insertions of these muscles. 8. Extensor com- munis digitorum. 9. Extensor corn- munis digitorum. 10. Extensor carpi ulnaris. 11. Anconeus. 12. Flexor carpi ulnaris. 13. Extensor minor pollicis. 14. Extensor maj or pollicis. 15. Posterior annular ligament. MUSCLES OP THE HAND. 155 Extensor minor pollicis. Origin, back of ulna below its middle, and interosseous ligament. Course, downwards on the back of the radius. Insertion, first phalanx of the thumb. Action, to extend the first bone of the thumb. Extensor ossis metacarpi pollicis. Origin, posterior surface of the middle of the ulna, interosseous ligament and radius. Course, downwards, its tendon passing through a groove of the radius. In- sertion, into the trapezium, and the metacarpal bone of the thumb. Action, to extend the metacarpal, and with it the whole thumb. Indicator. Origin, back of ulna near its middle, and interosseous ligament. Course, downwards. Insertion, with tendon of extensor communis, into the whole back of the forefinger. Action, to extend the forefinger, as in pointing. MUSCLES OF THE HAND. Abductor pollicis. Origin, trapezium, trapezoid, and annular ligament Insertion, base of first phalanx of thumb. Action, to draw the thumb away from the forefinger. Opponens pollicis. Origin, point of the trapezium, and the annular ligament. Insertion, radial side of metacarpal of the thumb. Action, to draw the metacarpal and thumb towards the palm of the hand. Flexor brevis pollicis. Origin, by two heads; one, from the trapezium and trapezoid ; the other, from the magnum, unciform, and metacarpal of the middle finger. Between the two passes the tendon of the flexor longus pollicis. Insertions, into the two sesa- nioid bones of the first joint of the thumb. Action, to flex the first phalanx of the thumb. Adductor pollicis Origin, ulnar side of second metacarpal bone; its fibres converging thence towards the insertion. Insertion, base of first phalanx of thumb. Action, to draw the thumb towards the forefinger. Palmaris brevis Origin, annular ligament of wrist in front, and palmar aponeurosis. Insertion, into the tegument on the inner side of the hand. Action, to draw up the skin on the palm. Lumbricales. Origin (four in number), each from the outside of a tendon of the flexor profundus digitorum. Insertion, with the tendons of the extensor communis, into the middle of the backs of the first phalanges of the fingers. Action, to hold in place the flexor and extensor tendons, and to flex the fingers. Abductor minimi digiti. Origin, pisiform bone and annular ligament. Insertion, inner side of first phalanx of little finger. Action, to remove the little finger from the next. Adductor metacarpi minimi digiti. Origin, hook of the unci- form bone. Insertion, metacarpal of little finger. Action, to flex the little finger, and approximate it to the rest. Flexor parvus minimi digiti. Origin, hook of the unciform. 156 ANATOMY. Insertion, first phalanx of little finger. Action, to bend that finger. Interossei. These are seven in number; three palmar and four dorsal. They arise from the sides of the metacarpal bones, and are inserted, with the lumbricales, into the sides of the first phalanges. They all act either as adductors or abductors of the fingers accord- ing to their position. MUSCLES OF THE PELVIS AND THIGH. Glutens maximus. Origin, from the posterior part of the crest of the ilium, and the dorsum near it ; the side of the sacrum and coccyx ; and the posterior sacro-sciatic ligament. Course, forwards and somewhat downwards, going over the great trochanter of the femur. Insertion, into the upper third of the linea aspera of the femur. Action, to draw the thigh backwards ; or to maintain the balance of the body upon the lower extremity. Glutens medius. Origin, anterior two-thirds of crest of ilium, and dorsum ilii between the crest and the semi-circular ridge. Course, under the gluteus maximus, converging, to a broad strong tendon. Insertion, into the great trochanter and adjacent part of the shaft of the femur. Action, to draw the thigh backwards and outwards. Gluteus minimus Origin, dorsum ilii between the semi-circular ridge and the hip-joint. Course, downwards, converging under the gluteus medius. Insertion, into the great trochanter. Action, to draw the thigh outwards and rotate it. Pyriformis. Origin, anterior face of the sacrum. Course, in a conical form, leaving the pelvis through the sacro-sciatic foramen. Insertion, into the great trochanter. Action, to rotate the thigh outwards. Gemelli. Origin, by two heads; one from the spine and the other from the tuberosity of the ischium. The tendon of the ob- turator goes between the two. Course, forwards and outwards. Insertion, into the great trochanter. Action, to rotate the thigh outwards. Obturator internus. Origin, from the margin of the thyroid foramen, except where the vessels pass through it. Course, con- verging to a round tendon which goes over the spine and tuberosity of the ischium as a pulley. Insertion, into the great trochanter. Action, to rotate the thigh outwards. Obturator externus. Origin, outer margin of the thyroid fora- men. Course, converging, outwards. Insertion, great trochanter. Action, to rotate the thigh outwards. Quadratus femoris. Origin, tuberosity of the ischium. Course, transversely outwards. Insertion, the ridge between the two tro- chanters. Action, to rotate the thigh outwards. MUSCLES OF THE PELVIS AND THIGH. 15*7 Fig. 71. 3 DEEP-SEATED MUSCLES ON THE POSTERIOR PART OF THE HIP-JOINT 1. Fifth lumbar' vertebra. 2. Ilio-lurnbar ligament. 3. Crest of the ilium. 4. Anterior superior spinous process. 5. Origin of the fascia femoris. 6. Gluteus medius. 7. Its lower and anterior portion. 8. Pyriformis. 9. Gemini. 10. Trochanter major. 11. Insertion of the gluteus medius. 12. Quadratus femoris. 13. Part of the adductor magnns. 14. Insertion of the gluteus magnus. 15. Vastus externus. 16 Longhead of the biceps. 17. Semi-mernbra nosus. 18 Semi-tendinosus. 19. Tuber ischii. 20. Obturator internus. 21. Point of the coccyx. 22. Posterior coccygeal ligament. 23, 24. Greater sacro-sciatic ligament. 25. Posterior superior spinous process of ilium. 26. Posterior sacro-iliac ligaments. Sartorius. Origin^ anterior superior spinous process of the ilium. Course, downwards and inwards, crossing the length of the thigh ; it being the longest muscle in the body. Insertion, inner side of the tubercle at the head of the tibia. Action, to bend the leg and draw it across the other. Tensor v a gince femoris. Origin, anterior superior spinous pro- cess of the ilium. Course, downwards and a little backwards. 14 158 ANATOMY. Insertion, into the fascia femoris on the outside of the thigh. Action, to make the fascia tense, and rotate the thigh inwards. Rectus femoris. Origin, anterior inferior spine of ilium, and from the same bone above the acetabulum. Course, downwards over the front of the thigh. Insertion, into the upper edge of the patella. Action, by the ligamenturn patellae, to straighten or ex- tend the leg. Crurceus; Origin, front of femur and its sides to the linea aspera. Course, downwards upon the femur. Insertion, into the patella. Action, to extend the leg. Vastus externus. Origin, outer part of femur below the tro- chanter major, and the whole length of the linea aspera. Course, downwards on the outside of the thigh. Insertion, the patella. Action, to extend the leg. Vastus internus. Origin, front of femur and whole length of linea aspera. Course, downwards, on the inside of the thigh. Insertion, the patella. Action, to extend the leg. The last four muscles are sometimes called, together, the quad- riceps femoris. Pectineus. Origin, the upper part of the pubes, between the linea ilio-pectinea and the ridge above the thyroid foramen. Course, obliquely, in flattened form, downwards and outwards. Insertion, into the linea aspera, below the lesser trochanter. Action, to draw the thigh inwards and upwards, and to rotate it outwards. Adductor longus. Origin, pubes near the symphysis. Course, downwards and outwards. Insertion, middle third of linea aspera. Action, to draw the thigh inwards and upwards. Adductor brevis. Origin, pubes, below the last named. Course, downwards and outwards. Insertion, upper third of linea aspera. Action, as the adductor longus. Adductor magnus. Origin, body and ramus of pubes, and ramus of ischium. Course, downwards and outwards. Insertion, whole length of linea aspera, and internal condyle. Action, the same as the last two muscles. Gracilis. Origin, pubes near the symphysis. Course, down- wards and outwards. Insertion, the tubercle of the tibia. Action, to flex the leg, and adduct the thigh. Semi-ten dinosus. Origin, tuberosity of ischium. Course, down- wards ; becoming tendinous about four inches above the knee. Insertion, by a round tendon, into the inner side of the tibia, below its tubercle. Action, to bend the leg on the thigh. Semi-membranosus. Origin, tuberosity of the ischium. Course, downwards. Insertion, the inner and back part of the head of the tibia. Action, to bend the leg. The three last-named muscles constitute the inner ham-string. Biceps flexor cruris. Origin, by two heads; one, from the tuberosity of the ischium ; the other, from the liuea aspera, high MUSCLES OF THE LEG. 159 np. Course, downwards. Insertion, Fig- 72. into the head of the fibula. Action, to bend the leg. -This muscle forms the outer ham- string. MUSCLES OP THE LEG. Tibialis anticus. Origin, head of the tibia, and upper half of the inter- osseous ligament. Course, downwards upon the outer face of the tibia, send- ing its tendon over the astragalus in front of the internal malleolus. Inser- tion, the front of the internal cuneiform bone on the sole of the foot. Action, to raise the foot towards the leg, and turn the sole inwards. JZxtensor longus digitorum. Origin, head of the tibia, interosseous ligament, and head, and nearly the whole length of the fibula. Course, downwards, giving off four tendons which pass under the annular ligament. Insertion, ench tendon into nearly the whole length of one of the toes, leaving out the great toe. Action, to extend the toes. Extensor proprius pollicis pedis. Origin, from the fibula, beginning three or four inches below its head. Course, downwards, its tendon going under the annular ligament. Insertion, into the whole length of the great toe. Action, to extend the great toe. The last two muscles will also aid in raising the foot towards the front of the leg. Peroneus longus. Origin, head and shaft of the fibula to within three or four inches of the ankle. Course, downwards, its tendon passing through a groove in the external raalleolus, the sinuosity of the os calcis, and a groove of the cuboid bone, to the middle of the sole. Insertion, outside of the base of the first metatarsal, and internal cuneiform bone. Action, to depress the foot and incline the sole outwards. Peroneus brevis. Origin, outside of fibula from just above its middle to the external malleolus. Course, downwards, through the same groove of the malleolus with the peroneus longns, and MUSCLES OF THE BACK OF THE THIGH. 1. Glutens raedius. 2. Glnteusmagnus. 3. Fascia lata. 4,- Long head of biceps. 5. Short head of biceps. 6. Semi-tendinosus. 7, 7. Semi-merabranosus. 8. Gra- cilis. 9. Adductor magnus. 10. Sartorius. 11. Popliteal space. 12. Gastrocnemius. 160 ANATOMY. through a fossa on the outer sur- face of the os calcis. Insertion, base of nietatarsal of the little toe. Action, same as peroneus longus. Peroneus tertius. Origin, middle of the fibula. Course, downwards to the outer malleolus, sending a tendon under the annular ligament. Insertion, base of metatarsal of the little toe. Action, to raise the foot owards the front of the leg. Gastrocnemius. Origin, by two heads ; one from the inner condyle of the femur and ridge leading to the lineaaspera; the other from the outer condyle and adjacent ridge. Course, as a double-bellied muscle, downwards, forming the outer part of the calf of the leg. Insertion, with the next muscle, by the tendo Achillis, into the os calcis, behind and below. Action, to raise the heel, and thus depress the foot ; this action is called, in anatomy, the extension of the foot. Soleus. Origin, beneath the last named, by two heads; one from the head and upper part of the fibula, the other from the back of the tibia, for some inches, below the popliteus muscle. Course, down- wards to the Achillis tendon. In- sertion, with the gastrocnemius', into the os calcis. Plantaris. Origin, external rrwndyle of femur, and capsnlar ligament of the knee. Course, soon becoming tendinous and slender, downwards. Insertion, os calcis, below the tendo Aehillis. Action, to depress or extend the foot. It is a feeble muscle, and sometimes absent. Popliteus. Origin, external condyle of femur, and capsular ligament of the knee. Course, inwards and downwards behind the knee. Insertion, a ridge at the inner and upper part of the tibia just below its head. Action, to bend the leg slightly, and rotate it inwards, and to draw tense the capsular ligament. Flexor longus pollicispedis. Origin, back of the tfbia, from about MCJSCLES OP THE FRONT OF THE LEG. 1. Tendon of qnadriceps. 2. Spine of tibia. 3. Tibialis anticus. 4. Extensor communis digitorum. 5. Extensor pro- prius pollicis. 6. Peroneus tertius. 7. Peroneus longus. 8. Peroneus brevis. 9, ,0. Soleus. 10. Gastrocnemius. 11. Extensor brevis digitorum. MUSCLES OP THE LEG. 161 three inches below the head almost to the ankle. Course, down- wards, through a groove in the back of the tibia and of the astra- galus. Insertion, into the last phalanx of the great toe. Action, to flex the great toe. Flexor longus digitornm pedis. Origin, back and inside of tibia from below the popliteus almost to the ankle; also from the outer edge of the tibia above the ankle. Course, downwards, in contact with the tibialis posticus ; its tendon passing behind the inner malleolus, and through the sinuosity of the os calcis to the middle of the sole of the foot. There it receives a slip from the flexor longus pollicis, and divides into four tendons, which perforate those of the-flexor brevis digitorum. Insertion, each tendon into the last phalanx of one of the four lesser toes. Action, to flex the toes and depress or extend the foot. Tibialis posticus. Origin, upper front of tibia, and, going through the interosseous ligament, also from the back of the tibia and fibula most of their length. Course, downwards, the tendon going through a groove of the inner malleolus. Insertion, inner face of os naviculare, and under surface of the tarsus, one slip reaching to the middle metatarsal bone. Action, to extend or depress the foot and turn the toes inwards. Extensor brevis digitorum pedis. Origin, front and outer part of the os calcis. Insertion, by four tendons, into all the toes but the last, under the insertions of the extensor longus digitorum. Action, to extend the toes. Flexor brevis digitorum pedis. Origin, great tuberosity of os calcis, and plantar aponeurosis. Insertion, by four tendons, per- forated by those of the flexor longus, into the second phalanges of the four lesser toes. Action, to flex the toes. The remaining muscles of the foot are small, and similar to the corresponding ones in the hand ; so that their description may be here omitted. Their names are as follows : four dorsal and three plantar interossei, abductors and adductors of the toes ; abductor pollicis pedis, abductor minimi digiti, flexor accessories, four lum- bricirles pedis, flexor brevis pollicis, adductor pollicis pedis, flf.cor brevis minimi diyiti, transvcrsalis pedis. 14* 162 A N A T M Y . Fig. 74 CHAPTER IX. NERVOUS SYSTEM. Portions Cerebro-spinal axis, ganglia, and nerves. Minute Structure. Two sorts of nervous tissue exist : the white (fibrous or) tubular, and the (cineritious or) gray, vesicular. The former is seen in the proper tubular fibres, prevailing in the cerebro-spinal system, and the gelatinous fibres, most common in the ^ganglionic system. In the tubular, under the microscope, the nerve is seen to consist of the central transparent axis cylinder, and the peripheral white substance of Schwann. In the gelatinous fibres, the white sub- stance is almost absent. The diameter of the tubular fibres is about ^g^TF of an inch. The gelatinous are less than half as large. Vesicular nerve-substance is found in the brain and ganglia. It is formed of cells, each with a nucleus or central vesicle, and within that a clear nucleolus. Some are small and round or oval; others larger, and caudated or stellated, the processes sometimes dividing into minute branches. Chemical Composition. Nervous tissue contains albumen, or an albuminoid mate- rial, with fatty matter (cerebric and oleo- phosphoric acids, cholesterin, olein, and margarin) and salts (phosphates and lac- tates). ANTERIOR VIEW OP THE BRAIN AND SPINAL MARROW.!, 1. Hemispheres of the cerebrum. 2. Great middle fissure. 3. Cerebellum. 4. Olfactory Nerves. 5. Optic nerves, (i. Corpora albicantia. 7. Motor oculi nerves. 8. Pons Va- rolii. 9. Fourth pair of nerves. 10. Lower portion of the medulla oblongata. 11, 11. Medulla spinalis in its whole length. 12, 12. Spinal nerves. 13. Cauda equiua. MEMBRANES. 163 Connections and Terminations. Doubt yet exists as to these. Sometimes, at the centres or ganglia, a nerve-tube seems to dilate and receive a nerve-cell or corpuscle within it. The processes of caudate vesicles are described as extending into nerves. Whether nerves ever terminate, peripherally, by free ends, or always by loops or meshes, is undecided. Beale insists that every nerve fila- ment makes part of a completed circuit. Nerves are round or flattened cords, each containing a number of filaments or tubules inclosed in a sheath (neurilemma), and con- necting a nerve-centre with some other part. In their course, they branch frequently, and sometimes form plexuses; but no two fila- ments ever truly unite or inosculate. THE BRAIN. Membranes. These are, the dura mater, arachnoid, and pia, mater. The dura mater is a thick fibrous membrane, with a smooth epithelial lining. It adheres to the skull, especially at its base and along the sutures ; and is continuous with the dura mater of the spinal cord, and with the sheath of the optic and other cephalic nerves. Three processes pass inwards from it; the falx cerebri, falx eerebelli, and the tentorium. The falx cerebri descends verti- cally between the hemispheres of the brain. In front, it connects with the crista galli of the ethmoid bone; behind, it widens, arid joins the tentorium. Above, it is broad, containing the longitudinal sinus. In its lower curved edge is the inferior longitudinal sinus. The falx cerebelli is a smaller triangular process, between the two lobes of the cerebellum. It passes from the under and poste- rior part of the tentorium to the occiput. The tentorium is an arched layer of dura mater covering the cerebellum, beneath the posterior lobes of the cerebrum. It is connected behind with the occiput, at the sides with the temporal bones, and on its middle line above, with the edge of the falx cerebri. The anterior border is free and^concave, with a large oval passage for the crura cerebri. The arteries of the dura mater are, principally, the anterior meningeal arteries, from the ethmoidal and internal carotid ; mid- dle and small raeningeal, from the internal maxillary; the poste- rior meningeal from the occipital, and the posterior meningeal from the vertebral. Its veins, which, like its arteries, are also those of the con- tiguous bones, anastomose with the diploic veins, terminating in the sinuses, with two minor exceptions which attend the middle meningeal artery. The nerves of the dura mater are the recurrent of the fourth, 164 ANATOMY. and filaments from the ophthalmic, ganglion of Casser, and sympa- thetic. Glandulce Pacchioni are small whitish granulations found on both the outer and inner surfaces of the dura mater, near the superior longitudinal sinus, and on the pia mater of the same re- gion. They are fibro-cellular in structure ; absent in infancy, they increase gradually in number after the seventh year ; but are sometimes wanting. Arachnoid Membrane. This is the middle serous membrane of the brain, described by most anatomists as double, one layer lining the dura mater, and the other investing the brain. It is very thin ; thickest at the base of the hemispheres. It does not descend between the convolu- tions, but passes over them. The sub-arachnoid space is between the arachnoid and the pia mater. It contains the serous cerebro- spinal fluid. Pia Mater. A fine but extended plexus of bloodvessels, held together by delicate connective tissue, investing the whole braiu, and dipping between the convolutions, receives this name. The pia mater is extended into the interior of the cerebrum, making the velum in- terpositum and the choroid plexuses of the fourth ventricle. Some long straight vessels pass from it through the white substance. Brain or Encephalon. We divide this into the cerebrum, cerebellum, medulla oblongata, and pons Varolii. The average weight of the whole mass in the adult male is nearly fifty ounces ; in the female, less than forty-five ounces. The maximum is about sixty-five ounces. Up to nearly forty years of age, in both sexes, it increases; after that, it loses about an ounce of weight with each ten years of age. Cerebrum. As no description can enable the student to understand the anatomy of the brain without repeated dissections, we shall at- tempt but a very brief statement especially of the terms applied to its parts. The cerebrum is an ovoidal mass, divided into the right and left hemispheres ; which are partly separated by the great longitu- dinal fissure. The surface of each hemisphere, under the pia mater, is marked by convolutions; these being different in different brains, and even upon the two hemispheres in the same subject. Gray vesicular nerve-substance predominates in the convolutions, although alternating thin layers of white substance exist. CEREBRUM. Fig. 75. 165 BASE OF THE CEREBRUM AND CEREBELLUM. 1. Fissure of the hemispheres 2. Posterior extremity of the same fissure. 3. Anterior lohes of the cerebrum. 4. Its middle lobe. 5. Fissure of Sylvius. 6. Posterior lobe of the cerebrum. 7. Infundibulum. 8. Its body. 9. Corpora albicantia. 10. Cineritious matter. 11. Crura cerebri. 12. PODS Varolii. 13. Medulla oblongata. 14. Posterior prolongation of the pous Varolii. 15. Middle of the cerebellum. 16. Anterior, part of the cerebellum. 17. Its posterior part and fissure. 18. Medulla spinalis. 19. Middle fissure of the medulla oblongata. 20. Corpus pyraini.- dale. 21. Corpus restiforme. 22. Corpus olivare. 23. Olfactory nerve. 24. Its bulb. 25. Its external root. 26. Its middle root. 27 Its internal root. 28. Optic nerve beyond the chiasm. 29. Opic nerve before the chiasm. 30. Third pair of nerves. 31. Fourth pair. 32. Fifth pair. 33. Sixth pair. 34. Facial nerve. 35. Auditory. 36, 37, 38. Eighth pair of nerves. The base of each hemisphere presents a division into the ante- rior, middle, and posterior lobes. The fissure of Sylvius, on each side, separates the middle from the anterior lobe. The posterior lobe rests upon the tentorium. The fissure of Sylvius lodges the middle cerebral artery. The island of Reil is the name given to some convolutions inclosed within the sides of the fissue. Laying the brain over to examine its basal surface, the order of location of parts is as follows : from before backwards, longitu- dinal fissure ; on each side of this, bulb and trunk of olfactory 166 ANATOMY. nerve ; pituitary body, resting upon the sella Tnrcica of the sphenoid bone; attached to the body, the infundibulam ; connected with this, also, back of the chiasm or union of the optic nerves, the tuber cinereum; corpora albicantia, or eminentia mamillares; crura cerebri; ports Varolii ; medulla oblong ata ; with the lobes of the cerebellum at its sides. The anterior perforated space, or locus quadratus, is at the inner end of the fissure of Sylvius, at the entrance of the branches of the olfactory nerve. The tuber cinereum is a small prominence of gray nerve substance, between the optic commissure and the corpora albicantia ; it forms part of the floor of the third ventricle. The pituitary body is a small reddish, vascular, oval mass ; having two lobes ; it is proportionally larger in the foetus than in the adult. It has a cavity, leading through the infundibulum to the third ventricle. Its structure resembles that' of the ductless glands. The corpora albicantia are two small round bodies, of the size of peas, just back of the tuber cinereura. The pons Tarini or posterior perforated space, lies back of the corpora albicantia. Minute bloodvessels pass through it. The crura cerebri are bundles of white nerve-substance diverg- ing from the pons Varolii into the hemispheres, and wideBing as they Fig. 76. LONGITUDINAL SECTION OF THE BRAIN. 1. Left hemisphere. 2. Cerebellum. 3 Medulla oblongata. 4. Corpus callosura. 5. Fornix. 6. Cms of fornix. 7. Corpus albicans. 8. Septum lucidum. 9. Velum interpositum. 10. Middle commissure. 12. Posterior commissure. 13. Corpora quadrigemina. 15. Aqueduct of Sylvius. 17. Pons Varolii. 18. Crus cerebri. 19. Tuber ciuereum. 20. Optic nerve. 21. Olfactory nerve. pass forwards. In the interior of each crus is the dark gray locus niger. The third nerve (motor oculi) comes out from the crus ; the fourth winds around it. To examine the interior of the brain, it may be placed upon its CEREBRUM. 16? base, and sliced away above the level of the corpus callosum or great transverse commissure joining the hemispheres. The mass of white substance, centrum ovale, is thus diplayed. The corpus callosum is continuous behind the fornix. Removing or cutting through the corpus callosum, the lateral ventricles are exposed ; with the septum lucidum for their thin dividing partition. The floor of each lateral ventricle is formed of the corpus striatum, tcenia semi-circularis, thalamus opticus, choroid plexus, corpus Jimbriatum, and fornix. Their roof is the corpus callosum. The fornix is a triangular plane of white nerve-substance, of which the point is forwards. It is about the twelfth of an inch in thickness. It is supported by its anterior and posterior crura or curved pillars, which pass into the other parts of the brain. Its base, between the posterior crura, is continuous with the corpus callosum. The foramen of Monro is a bifurcating opening or passage, from Fig. 77. LATERAL VENTRICLES OF THE CEREBRPM. 1, 1. The two hemispheres cut down. 2. A small portion of the corpus callosum. 3. Its posterior boundary. 4. Septum lucidum. 5. Anterior cornu. 6. Middle cornu. 7. Posterior cornu. 8. Corpus striatum. 9. Taenia striata. 10. Thalamus opticus. 11. Plexus choroides. 12. Fornix. 13 Hippocampus major. the third ventricle below, upwards into the two lateral ventricles ; just behind the anterior pillars of the fornix. The choroid plexus is prolonged through it. The septum lucidum, between the two lateral ventricles, is formed 1C8 ANATOMY. of two laminae or layers, between which is the cavity called the fifth ventricle. The cornua of the lateral ventricles are the anterior, middle, and posterior. The anterior cornu is a curved triangular cavity passing outwards and forwards in the substance of the anterior lobe, in front of the corpus striatum. The middle cornu descends tortuously to terminate in the middle lobe. It contains within it the hippocampus major, pes hippo- campi, pes accessorius, corpus fimbriatum, choroid plexus, fascia dentata, and transverse fissure. The hippocampus major, or cornu ammonis, is a true convolution of the lateral edge of the hemisphere. The corpus fimbriatum, or tsBnia hippocampi, is a tape-like band of white nerve-substance attached to the inner border of the hippocampus. The pes hippo- campi is a series of knotted elevations at the termination of the hippocampus major in front. Pes accessorius is behind the hippo- campus major, between it and hippocampus minor. The fascia dentata, or corpus denticulatum, is a narrow serrated layer of gray nerve-substance, displayed by raising the edge of the corpus fimbriatura. The posterior cornu curves into the posterior lobe of the hemisphere. Its floor has a prominent cord-like elevation, the hippocampus minor. The corpora striata are two elongated pear-shaped masses, making parts of the floor of the lateral ventricles. Externally, they are of gray vesicular nerve-substance ; within, they contain also a number of white medullary or tubular filaments. These are connected with the anterior or motor columns of the crura cerebri ; and, through them, with the corpora pyramidalia of the medulla oblongata. The thalami (optici) are rounded masses lying posterior to the corpora striata, and partly inclosed between them. They are composed externally of white nerve-substance, which, within, is blended and laminated with gray vesicular neurine. All the nerves of sensation are more or less directly connected with the thalami, or with the corpora olivaria of the medulla oblongata which are continuous with them. The tcenia semicircularis is a narrow cord of white nerve-sub- stance, between the thalamus and the corpus striatum. Beneath it is a vein, the vena Galeni, which ends in the choroid plexus. When the anterior crura of the fornix are divided and it is thrown backwards, a delicate membranous network is seen, which is the velum interpositum. Removing this, we expose under it the third ventricle. The velum interpositum is a continuation of the pia mater. The choroid plexus, on each side, is the lateral margin of the velum interpositum ; it consists of a red fringe of tortuous arteries CEREBRUM. 169 and veins. The two choroid plexuses meet at the foramen of Monro. The third ventricle is a narrow, oblong fissure, roofed by the fornix, floored by the posterior perforated space, corpora albican- tia, tuber cinereum, and crura cerebri. It contains three transverse commissures, anterior, middle, and posterior. The middle is also called the soft commissure. The iter ad quartum ventricubim, or aqueduct of Sylvius, is a canal from the posterior part of the third ventricle under the tubercula quadrigemina into the fourth ventricle. The iter ad infundibulum is a canal from the anterior part of the third ventricle downwards into the infundibulura. Behind the posterior commissure, are the small rounded bodies called tubercula quadrigemina, or nates and testes. The former are larger and anterior. They are connected with the optic thalamus by a bundle of white nerve-filaments also communicating with the cerebellum, called the processus e cerebello ad testes. The tubercula are thus between the cerebrum and cerebellum, and almost equally connected with both. The valve of Vieussens, or valve of the brain, is a thin plane of white neurine continuous with the lower margin of the testes, whence it extends as the roof of the fourth ventricle. The pineal gland is a conical mass of gray nerve-substance, lying beneath the base of the fornix upon the nates of the tubercula quadrigemina. It is joined to the velum interpositum ; and, by two peduncles, to the thalami and crura of the fornix. Without any reason, it has been imagined to be the special seat of the soul. The commissures or connecting portions of the brain, composed of bands or bundles of white tubular nerve-filaments, are the supe- rior longitudinal, above the corpus callosum within each hemi- sphere of the cerebrum, the fornix or inferior longitudinal com mis- sure, the corpus callosum, and the three transverse commissures of the third ventricle. The pons Varolii is the transverse commissure of the cerebellum. The valve of Vieussens and processus e cerebello ad testes make a cerebro-cerebellar connection or commissure. Cerebellum. The cerebellum is much smaller than the cerebrum, averaging in weight a little over five ounces in the adult. It is behind and below the cerebral hemispheres. It consists of a right and a left lateral hemisphere, divided from each other by a fissure ; this being interrupted above by a ridge-like connection called the median lobe or superior vermiform process; and below, by the inferior vermiform process. A. horizontal fissure also divides each hemi- sphere into an upper and a lower portion ; and out of this fissure proceed several lesser ones. 15 170 ANATOMY. The outer portion of the cerebellum consists of a large number of delicate layers or lamellce, laid one upon another. Making a vertical section of it, we see a tree-like arrangement within, called the arbor vitce ; consisting of white nerve substance inclosed in vesicular neurine. In the trunk of the arbor vitae is an irregu- lar mass of vesicular nerve substance, the corpus dentatum. The proportion of gray nerve-matter is large in the cerebellum, making the whole of its exterior lamellar surface. The pia mater dips in between its layers. The name of peduncles of the cerebellum is sometimes given to 1, the processus e cerebello ad testes, previously described ; 2, the crura cerebelli ; 3, the corpora restiformia, extending to the medulla oblongata. The crura cerebelli radiate from the pons Varolii (great transverse commissure of the cerebellum) into all parts of the cerebellum. The fourth ventricle is a cavity between the medulla oblongata in front and the cerebellum behind. It is somewhat triangular, nar- rowest above. Its floor is the medulla oblongata and pons Yarolii ; its -roof, the valve of Yieussens and tubercula quadrigemina. It communicates with the third ventricle by the iter e tertio ad quar- tum ventriculum,or aqueduct of Sylvius. The longitudinal fissure in the floor of the fourth ventricle presents a pen-like form, called the calamus scriptorius. The pons Varolii, or tuber annulare, already named, is a rounded mass of about an inch in diameter, resting by its convex surface upon the clivis or junction of the occiput and sphenoid bone. It is composed of white tubular filaments, nearly all transverse, blended with gray vesicular nerve-substance. The transverse fibres connect the hemispheres of the cerebellum. The longitudinal filaments are continuous with the corpora pyramidalia of the medulla oblongata behind, and, in front, with the crura cerebri. Medulla Oblongata. Being the connecting portion between the spinal cord and the brain, the lower and posterior boundary of the medulla obiongata is the foramen magnum occipitis. Its form is pyramidal; its length, to the pons Yarolii, about an inch and a quarter. Besides an anterior and a posterior longitudinal fissure, continu- ous with the fissures of the spinal cord, it is, by other sulci or fur- rows, subdivided into four portions ; the corpora pyramidalia, cor- pora olivaria, corpora restiformia, and posterior ganglia. The corpora pyramidalia are anterior. They consist of bundles of white tubular nerve-substance. A decussation or crossing over of a fasciculus of each pyramid occurs about three-fourths of an inch below the pons. Above, after penetrating the pons, the corpora pyramidalia expand, and, passing on through or forming part of SPINAL CORD. HI the crura cerebri, diverge to form a large part of the cerebral hemispheres. The corpora olivaria are two elliptical bodies, external to the pyramidalia. They are composed of a mixture of white and gray nerve-substance ; having a covering of the white, then a mass of gray vesicular material (corpus dent-atom), and within this a cen- tral white portion. They send fibres to the tubercula quadrigemina and thalami. The corpora restiformia are the posterior and lateral rope-like prolongations of the antero-lateral and posterior columns of the spinal cord. Above, they pass into the cerebellum, as the crura cerebelli. The posterior ganglia or posterior pyramids are smaller, and lie next to the posterior fissure. They are entirely of white nerve- substance, continuous with the posterior tracts of the spinal cord. SPINAL CORD. The length of the spinal cord from the foramen magnum occipitis to the cauda equina in the lumbar region, averages about eighteen inches. Its width is greatest in the upper cervical region ; less in the middle dorsal ; enlarged again in the lower dorsal ; and thence diminishing gradually to a conical point opposite the second lum- bar vertebra. Spinal Membranes. These are continuous with the dura mater, arachnoid, and pia mater of the brain. Adhering to the first cervical vertebra, the spinal dura mater is loose in the vertebral canal down to an at- tachment to the os coccygis. It invests, by processes, each of the spinal nerves to the intervertebral foramen, and surrounds the ganglion on the posterior root of each. The spinal arachnoid contains, between it and the pia mater, the cerebro-spinal fluid ; communicating with the subarachnoid space of the brain. The spinal pia mater is more dense and fibrous, and less vascu- lar, than the pia mater of the brain. Between it and the arach- noid, on each side of the cord, is a narrow band called the denticu- late ligament. This, being attached to the dura mater by fifteen or twenty processes, detains the membranes in their position in relation to the cord. Fissures of the Cord. The anterior fissure is the widest, but extends only to one-third of the diameter of the spinal marrow. At its bottom is a thin layer of white nerve-substance, the anterior commissure. The posterior fissure is deeper. At its bottom is a layer of gray nerve-substance. Both are lined by the pia mater. 172 ANATOMY. On each side is a lateral fissure ; somewhat back of the middle of the cord. This does not run the whole length of the cord. Anterior to this, and posterior to it, on each side, are lesser fis- sures, the a 'ntero -lateral and postero-lateral sulci ; corresponding with the anterior and posterior roots of the spinal nerves. Columns. Each half of the cord may be described as consisting of two columns; antero- lateral and posterior or postero-lateral column. The antero-lateral is much the larger; but the difference is greatest in the cervical region, and least in the lumbar. Structure of the Cord. A transverse section shows the gray vesicular nerve-substance to be inclosed within the white medullary portion. The gray substance presents, in section, the form of two crescents, connected by a commissure. The white columns are also joined by the ante- rior commissure. The white substance is composed of longitudi- nal laminae of tubular filaments, in contact by their inner portion with the gray matter of the cord. Origin of the Spinal Nerves. There are, of these nerves, thirty-one pair ; eight cervical, twelve dorsal, five lumbar, and six sacral nerves, for each side. Each nerve has its anterior and posterior roots. The anterior roots arise from the antero-lateral column, and emerge through the ante- rior lateral sulcus. The posterior roots enter the postero-lateral sulcus, to connect with the posterior column. All, or nearly all, the fibres of both roots proceed through the white columns into the gray substance. Those of both decussate freely from side to side, and also pass upwards and downwards, as well as diverge in all directions. The complete history of their terminations and connections remains yet to be finally traced. CRANIAL OR CEPHALIC NERVES. Though not in all respects a satisfactory arrangement, these are usually described as nine pair : 1st, olfactory; 2d, optic; 3d, motor oculi ; 4th, pathetic ; 5th, trifacial ; 6th, abducens oculi ; 7th, facial or portio dura, and auditory or portio mollis ; 8th, glosso- pharyngeal, pneumogastric, and spinal accessory ; 9th, hypoglos- sal. Olfactory nerve. Arising (to use the common language of anatomists) by three roots, from the anterior and middle parts of the base of the cerebrum, the first nerve proceeds forward as a flat band upon the under surface of the anterior lobe, not far from the longitudinal fissure. On the ethmoid bone, it expands into CRANIAL OR CEPHALIC NERVES. 173 Fig. 78. the olfactory bulb; from which pass, through the cribriform plate of the ethmoid, about twenty filaments, to be distributed to the mucous (Schneiderian) membrane of the nostril. The olfactory nerve-trunk is soft, and contains gray matter in its interior. Optic nerve. The second nerve of each side unites with its fellow at the optic chiasm or commissure, within the skull, in front of the tuber cinereum. There a partial decussation oc- curs. Some fibres cross from the retina of one eyeball to that of the other; some from .one side of the brain to the other; some from the eye on one side to the brain on the other ; and some from each eye to the same side of the base of the brain. Back of the commissure, the optic tract divides on each side into two bands, which continue to the ihalami, the corpora aeni- culata, and the tubercala quad- rig emina. Anteriorly, the optic nerve of each side emerges by the optic foramen of the sphenoid bone, pierces the sclerotic and choroid coats of the eyeball a little to the nasal side of its centre, and is distributed to the retina. The arteria cen- tralis retince perforates it, with corresponding veins. Motor oculi. The third nerve originates in the crus cerebri in front of the pons Yarolii. After receiving a few filaments from the cavernous plexus of the sympathetic, it divides into two branches, which enter the orbit through the sphenoidal fissure. It is finally distributed to aH the muscles of the eyeball. Pathetic nerve. The fourth, sometimes called trochlear nerve, arises from the valve of Yieussens behind thetuberculaquadrigemina. Winding around the crus cerebri, it passes into the orbit through the sphenoid fissure. It supplies only the superior oblique muscle. Trifacial or fifth pair. This, the largest of the cephalic nerves, arises, like the spinal nerves, by two roots ; the posterior of which has a ganglion upon it. Both roots are connected with the medulla oblongata, through the pons Yarolii. Near the apex of the petrous 15* THE SECOND PAIR, OR OPTIC NERVKS. -1 , 1. Globe of the eye. 2. Chiasm of the optic nerves. 3. Corpora albicantia. 4. Infundibu. lura. 5. PODS Varolii. 6. Medulla oblongata. 7. Third pair. 8. Fourth pair. 9. Fifth pair. 10 Sixth pair. 11. Seventh pair. 12. Eighth pair. 13. Ninth pair. 174 ANATOMY. portion of the temporal bone, the posterior and larger root enters the Casserian (semilunar) ganglion. From this go off two great branches of the nerve, the ophthalmic SL\}(] superior maxillary ; which are therefore sensory nerves oniy. Below it, with fibres from both Fig. 79. DISTRIBUTION OF THE FIFTH PAIR. 1. Orbit. 2. Antrum Highinorianum. 3. Tongue. 4. Lower jaw-bone. 5. Root of the fifth pair forming the ganglion of Gasser. 6. First branch of the fifth pair. 7. Second branch. 8. Third branch. 9. Frontal branch. 10. Lachrymal branch. 11. Nasal branch. 12. Internal nasal nerve. 13. External nasal nerve. 14. External and internal frontal nerve. 15. Infra-orbital nerve. 16. Posterior dental branches. 17. Middle dental branch. IS. Anterior dental nerve. 19. Terminating branches of the infra-orbital nerve. 20. Orbitar branch. 21. Pterygoid, or recurrent nerve. 22. Five anterior branches. 23. Lingual branch of the fifth. 24. Inferior dental nerve. 25. Its mental branches. 26. Superficial temporal nerve. 27. Auricular branches. 28. Mylo-hyoid branch. roots, passes the inferior maxillary, which has sensory and motor filaments. The ophthalmic, or first branch of the fifth, goes out through the sphenoidal fissure ; the second or superior maxillary, through the foramen rotundum of the sphenoid bone ; the third, inferior maxillary, through the foramen ovale of the same bone. Ophthalmic nerve. The subdivisions of this are, the lachrymal, frontal, and nasal nerves. The lachrymal is smallest. It goes to the lachrymal gland, conjunctiva and tegument of the upper eye- lid. The frontal is larger. It divides into the siipra-trochlear and supra-orbital branches. The first is distributed to the corrugator CRANIAL OR CEPHALIC NERVES. 175 snpercilii and occipito-frontalis muscles and the tegument of the forehead. The snpra-orbital passes through the supra-orbital foramen, giving off filaments to the upper eyelid ; then terminating in muscular, cutaneous, and pericrania! branches, for the forehead and brow. The nasal nerve leaves the orbit by the anterior ethmoidal fora- men, enters the cavity of the cranium, goes over the cribriform plate of the ethmoid to the side of the crista galli, and there descends into the nose. Then it divides into the external and internal branches. The internal supplies the mucous membrane of the nostril, the external goes beneath the end of the nasal bone to be distributed with the facial nerve to the skin of the wing and- tip of the nose. Before this division, the nnsal nerve gives off the gangUonic, two long ciliary, and infra-trochlear branches. The ganglionic enters the ciliary ganglion. The long ciliary go to the ciliary muscle and iris, with the short ciliary nerves from the ganglion. The infra- trochlear goes to the parts about the inner angle of the eye. Superior maxillary nerve. Its subdivisions are, 1. In the spheno-maxillary fossa : orbital, spheno-palatine, posterior dental. 2. In the infra-orbital canal: anterior dental 3. On the face: palpebral, nasal, labial. The orbital branch splits into the temporal and malar. The former passes through the malar bone into the temporal muscle and integument. The malar goes through a foramen in the malar bone to join the facial. The two spheno-palatine branches go to the ganglion of the same name. The posterior dental branches form a plexus with the anterior dental, from which filaments go to the molar and bicuspid teeth ; supplying also the gums and bucci- nator muscle. The anterior dental nerve enters a canal in the front wall of the antrum, and joins with the posterior dental. It sends fibres to the incisor, canine, and bicuspid teeth ; some, also, to the tegument. The palpebral branches go to the muscle, conjunctiva, and tegu- ment of the lower eyelid. The nasal branches supply the side of the nose, joining with filaments of the ophthalmic. The labial branches are distributed to the skin and muscles of the upper lip and the mucous membrane of the mouth. All these branches contribute, with some from the facial nerve, to make the infra- orbital plexus, just below the orbit. Inferior maxillary nerve After its exit from the foramen ovale, this nerve divides into a smaller anterior and a larger posterior trunk. The former gives off masseteric, deep temporal, buccal, and pterygoid branches, to the muscles of mastication. The larger posterior portion divides into the auriculo-temporal, gustatory, and inferior dental nerves. 1T6 ANATOMY. The auricula-temporal goes to join the temporal artery near the articulation of the lower jaw ; thence upwards under the parotid gland, above which it divides into the anterior and pos- terior temporal branches. It has, first, the two auricular, the articular branches, two branches to the meatus auditorius, and parotid branches. The gustatory or lingual nerve is deeply placed, and supplies the mucous membrane and papillae of the tongue, anastomosing at the tip of the latter with the terminations of the hypoglossal nerve. The inferior dental nerve goes down with the inferior dental artery to the dental foramen. Then, in the dental canal, beneath the teeth of the lower jaw, it passes forwards to the mental fora- men ; where it divides into the incisor and mental branches. The former supplies the incisor and canine tooth-pulps The latter goes out at the mental foramen, and supplies the muscles, mucous membrane, and tegument of the lower lip. The inferior dental gives off, before this, the mylo-hyoid and dental branches. The latter go to the pulps of the molar and bicuspid teeth. Ganglia connected with the fifth nerve. These are: 1. The ophthalmic, lenticular, or ciliary ganglion ; 2. Spheno-palatine ganglion. 3. Otic ganglion (of Arnold) ; i. Submaxillary gan- glion. Belonging to the sympathetic system, these will all be described in connection with it. Abducens or sixth pair. This nerve originates from the medulla oblongata, close to the pons Varolii. It enters the orbit of the eye through the sphenoidal fissure, and is distributed to the ex- ternal rectus muscle of the eyeball. Facial nerve. This, the portio dura of the seventh pair, arises from the medulla oblongata, passes upon the crus cerebelli, and enters the internal auditory meatus with the portio moltis or audi- tory nerve. At the bottom of the meatus, it goes into and through the aqueduct of Fallopius of the petrous portion of the temporal bone. Then, emerging, from the stylo-mastoid foramen, it runs forward in the parotid gland, crossing the external carotid artery, to divide behind the ramus of the lower jaw into two primary branches, the temporo-facial and cervico-facial. Within the aqueduct of Fallopius, this nerve gives off the tympanic nerve and the chorda tympani. At its exit from the stylo-mastoid foramen, the posterior auricular, digastric, and stylo-hyoid. The temporo-facial branch divides into the temporal, malar, and infra- orbital nerves. The cervico-facial, into the buccal, supra-maxillary, and infra-maxillary. The tympanic branch supplies the stapedius and laxator tympani muscles. The chorda tympani ascends in a canal parallel to the aqueduct of Fallopius, passes into and through the cavity of the tympanum, emerges from it near the Glaserian fissure, descends to meet the CRANIAL OR CEPHALIC NERVES. 171 gustatory nerve, goes with it through the submaxillary gland, and terminates in the lingualis muscle. The posterior auricular divides into the auricular and occipital branches; the latter being the larger. The stylo-hyoid goes to the muscle of that name. The digastric, supplies the digastricus muscle ; a filament goes through this to join the glosso-pharyngeal nerve. Of the iemporo-facial division of the seventh, the temporal branches join with branches of the fifth pair to supply the oceipito- frontalis and orbicularis oculi muscles. The malar branches supply the orbicularis oculi and corrugator supercilii muscle. The infra-orbital branches are distributed, some deeply and others superficially, between the lower margin of the orbit and the mouth. The cervico-facial division of the facial nerve sends buccal branches to the buccinator and orbicularis oris ; supra-maxillary branches to the lower lip and chin ; and infra-maxillary branches, of which some join the superficial cervical nerve from the cervical plexus, and others supply the platysma myoides and levator labii inferioris muscles. The auditory nerve, portio mollis of the seventh pair, enters the meatus auditorins internus, and is distributed to all parts of the labyrinth or internal ear. Eighth pair. This is a threefold nerve, composed of the glosso- pharyngeal, pneumogastric, and spinal accessory. Glosso-pharyngeal. The origin of this is from the upper part of the medulla oblongata. Leaving the skull by the jugular foramen, it descends in front of the internal carotid artery, and arches on the side of the neck, to be finally distributed to the mucous mem- brane of the fauces, tonsils, and base of the tongue. While in the jugular foramen, this nerve has two enlargements, the. jugular and. petrous ganglia. The glosso-pharyngeal communicates by fila- ments with the pneumogastric, facial, and sympathetic nerves. A tympanic branch (nerve of Jacobson) goes off from the petrous ganglion, penetrates a canal of the temporal bone, enters the tympanum, and is there distributed, after dividing into three branches. The divisions of the glosso-pharyngeal nerve are, the carotid, pharyngeal, muscular, tonsillitic, and lingual. The carotid branches descend along the trunk of the internal carotid artery. The pharyngeal branches form the pharyngeal plexus with fila- ments of the pneumogastric, superior laryngeal, and sympathetic nerves. From this plexus nerves pass through the muscular coat of the pharynx to supply the mucous membrane. ITS ANATOMY. The muscular branches go principally to the stylo-pharyngeus muscle. The tonsillitic branches form a sort of plexus around the tonsil. The lingual branches are two. One goes to the base and the other to the side of the tongue. These are nerves of taste. Pneumogastric or par vagum. This part of the eighth pair arises from the medulla oblongata, and emerges from the cranium through the jugular foramen in the same sheath with the spinal accessory. In this foramen it presents an enlargement, called, sometimes, the ganglion of the root of the pneumogastric. Lower, it has the inferior ganglion, or ganglion of the trunk. It then descends within the sheath of the carotid ; but has a different course on the two sides of the body. On the right side, it crosses the subclavian artery and goes down beside the trachea to the root of the lung, where it forms a sort of plexus. From this two branches go to the oesophagus, making with those of the other side the cesophageal plexus. These branches unite below into a nerve which runs down back of the oesophagus to be distributed upon the posterior surface of the stomach. On the left side, the pneumogastric passes between the carotid and subclavian arteries, crosses the arch of the aorta, and descends behind the root of the lung and in front of the oesophagus, finally distributing branches over the anterior surface and lesser curvature of the stomach. The branches of the pneumogastric are the auricular, pharyngeal, superior laryngeal, recurrent laryngeal, cervical cardiac, thoracic cardiac, anterior and posterior pulmonary, cesophageal, and gastric branches. The auricular goes from the ganglion of the root, through the temporal bone, to the back of the ear. The pharyngeal arises from the inferior ganglion, and is dis- tributed to the muscles and mucous membrane of the pharynx ; some filaments terminating, with some from the glosso-pharyngeal, upon the internal carotid artery. The superior laryngeal goes from the inferior ganglion down by the side of the pharynx, and divides into the external and internal laryngeal. The external branch supplies the thyroid gland and crico-thyroid muscle. The internal passes to the mucous mem- brane of the larynx, and crico-arytenoid muscle. It communicates with the recurrent laryngeal. The inferior or recurrent laryngeal winds around the subclavian artery on the right side, around the aorta on the left, ascends between the trachea and oesophagus, and is by its branches dis- tributed to the muscles of the larynx, except the crico-thyroid. Cardiac, cesophageal, tracheal, and pharyngeal filaments go from it. CRANIAL OR CEPHALIC NERVES. 179 The cervical cardiac branches are two or three, which go to the great cardiac plexus, or to the cardiac branches of the sym- pathetic. The thoracic cardiac branches arise lower, and have a similar distribution. The anterior pulmonary branches are two or three small fasci- culi, which join with sympathetic fibres, to make the anterior pul- monary plexus. The posterior pulmonary are larger and more numerous ; they form the posterior pulmonary plexus by union with filaments of the sympathetic. Both of these sets of ramifications attend the air-tubes in their distribution into the lungs. The cesophageal and gastric branches have been already suffi- ciently described. Spinal accessory. This may be said to have two parts : the spinal portion and the portion accessory to the pneumogastric. The spinal part arises from the side of the spinal marrow, as low as the sixth cervical nerve, enters the cranium by the foramen magnum occipitis, again passes out by the jugular foramen, being there connected with the accessory portion ; then, going behind the internal jugular vein, it descends obliquely behind the digastric and stylo-hyoid muscles to the sterno-cleido-mastoid muscles ; finally, terminating in the trapezius muscle. The accessory portion is smaller. It arises not far below the origin of the pneumogastric, in the medulla oblongata; goes out through the jugular foramen, communicating there with the par vagum, whose pharyngeal and superior laryngeal branches it ac- companies in their distribution. Hypoglossal nerve. The ninth nerve of anatomists, more truly the twelfth of the series, originates in the medulla oblongata, and passes out through the anterior condyloid foramen of the occiput. Descending the neck, it winds around the occipital artery, crosses the external carotid, runs between the mylo-hyoid and hyoglossus muscles, to distribute branches to the whole of the tongue. Its main branches are, the descendens noni, thyro-hyoid, and muscular. The descendens noni is a slender branch, which goes across the sheath of the carotid vessels, making a loop with branches from the second and third cervical nerves. It sends thence filaments to the sterno-hyoid, sterno-thyroid, and omo-hyoid muscles; perhaps, also, to the phrenic and cardiac nerves. The thyro-hyoid goes to the muscle of that name. The muscu- lar branches supply the stylo-glossus, hyo-glossus, genio-hyoid, and genio-hyo-gloss.us muscles. Functions of Cephalic Nerves. So far as is yet ascertained, the following (from Gray) is a correct statement : 180 ANATOMY. NERVES OF SPECIAL SENSE. NERVES OF MOTION. Olfactory (1st), Motor oculi (3d), Optic (2d), Patheticus (4th), Auditory (portio mollis of 7th), Part of third branch of 5th, Part of glosso-pharyngeal (of Abducens oculi (6th), taste), Facial (portio dura of 7th), Lingual branch of 5th (of Hypoglossal (9th). taste). NERVES OF COMMON SENSATION. MIXED NERVES. Greater portion of 5th, Pneumogastric (part of 8th), Part of glosso-pharyngeal (of Spinal accessory (of 8th). 8th). SPINAL NERVES. Of these the roots have been described already, in their connec- tion with the spinal marrow. Upon each posterior root, in the intervertebral foramen, outside of the dura mater, there is a gan- glion ; just beyond this, the two roots unite into one trunk, which soon again subdivides into anterior and posterior branches ; each of which is furnished with filaments from both roots. The anterior branches are usually largest. Eight Cervical Nerves. The first leaves the spinal canal between the atlas and the occi- put. It is called the sub-occipital nerve. It divides, as do all the spinal nerves, into anterior and posterior branches. The former joins the second cervical nerve. The latter goes to the recti and obliqui capitis and complexus muscles. The second goes out between the atlas and the axis or second vertebra. Its anterior branch sends one fasciculus up to join the first nerve, and two down to connect with the third. Its posterior branch is larger, and goes to muscles of the back of the neck. The anterior branch of the third is twice as large as that of the second ; and so is the anterior branch of the fourth. Besides communicating with several other nerves, they unite at the cervi- cal plexus. Their posterior branches go to the trapezius and other neighboring muscles and the integument. Cervical plexus. This is formed by the anterior branches of the first four cervical nerves. It lies in front of the first four vertebrae. Its branches are superficial and deep. Of the first, there are the ascending ones, viz., superficialis colli, auricularis ma gnus, and occipitalis minor; and descending, the supra- clavicular, subdividing into the sternal, clavicular, and acromial nerves. Deep branches of this plexus are, the internal ones, viz , the communicating, mus- cular, communicans noni, and phrenic nerves; and external, the EIGHT CERVICAL NERVES Fig. 80. 181 THE NERVES. communicating and muscular nerves. These are distributed to the muscles and integument of the back of the head, and of the neck and chest. The phrenic nerve requires special description. Arising from the third and fourth cervical nerves, with a commu- nicating branch from the fifth, it descends to the root of the neck, 16 182 ANATOMY. Fig. 81. lying across the scalenus anticus muscle, passes between the snb- clavian artery and vein, and crosses the internal mammary artery as it enters the chest. The right phrenic nerve is shortest. It lies outside of the right vena innominate and the descending vena cava. The left phrenic crosses in front of the arch of the aorta to the root of the lung. Both are distributed to the diaphragm ; sending filaments also to the pleura and pericardium. The right nerve communicates with the phrenic branches of the solar plexus; the left, with the phrenic plexus. The Brachial Plexus. Brachial plexus. The anterior branches of the four cervical and the first dorsal nerves unite to form this. It extends from the lower portion of the neck to the axilla, and is quite wide. It communicates with the cervical plexus by a branch from the fourth to the fifth nerve. Its branches are 1. Above the clavicle : communicating, muscular, posterior thoracic, and su- pra-scapular. 2. Below the clavicle: to the chest, ante- rior thoracic ; to the shoul- der, subscapular, and cir- cumflex ; to the arm, fore- arm, and hand, musculo- cutaneous, internal cutane- ous, lesser internal cutane- ous, median, ulnar, and masculo-spiral. The communicating goes to the phrenic. The mus- cular branches go to the Rcaleni, longus colli, rhom- boideus, and subclavius muscles. The posterior thoracic is a long branch, going through the scalenus me- dius muscle down to the THE BKAOHIAL PLKXPS. 1, 1. Scalenns anticus Bottom of the SCITatUS 1. Median nerve. 3 Ulnar nerve. 4. which j t - di B iihcu'o-cutaneous nerve. 5. Thoracic nerves. c 6. Phrenic nerve. tl'lbuted. The supra - scapular iiervegoes beneath the trapezius muscle to pass through a notch in MEDIAN NEEVE. 183 the upper border of the scapula, to supply the supra-spinatus and infra-spinatus muscles. The anterior thoracic nerves are two, the external or superficial, and the internal or deep branch. They are distributed to the pectoralis muscles. The subscapular nerves are three ; they supply the subscapularis, teres major, and latissimus dorsi muscles. The circumflex nerve goes down behind the axillary artery, and, below the subscapularis muscle, divides into the upper and" lower branches. The upper winds around the neck of the humerus with the circumflex bloodvessels; supplying the deltoid muscle and the integument over it. The lower is distributed to the teres minor, deltoid, and triceps muscles, and integument over the last two. The musculo-cutaneous nerve perforates the coraco-brachialis muscle, passes between the biceps and brachialis anticus, and, after sending off muscular filaments, becomes cutaneous on the outer side of the arm above the elbow; near the elbow-joint it sub- divides into an anterior and a posterior branch. The anterior descends along the radial margin of the forearm, gets in front of the radial artery at the wrist, and goes with it to the back of the wrist. It receives a branch from the radial nerve. The posterior branch goes down back of the outer side of the forearm, to supply the skin of the lower part of the forearm ; communicating also with the radial nerve, and with the external cutaneous branch of the musculo-spiral nerve. The internal cutaneous nerve is a small branch of the brachial plexus. From its origin at the inner side of the brachial artery, it goes down along the arm to near its middle, when it emerges with the basilic vein, and divides into two cutaneous branches. Of these, the anterior branch goes usually in front of the median basilic vein ; occasionally, behind it. Then it passes down on the anterior surface of the ulnar side of the forearm to the wrist. The posterior branch winds over the inner condyle of the humerus to the back of the forearm and is there distributed to the integument. The lesser internal cutaneous nerve (nerve of Wrisberg) is the smallest branch of the brachial plexus. Passing through the axilla near the axillary vein, it goes with the brachial artery to the middle of the arm; then, perforating the fascia, it is distributed to the skin of the back of the arm. Median Nerve. The median is a more important nerve. Its two roots, from the brachial plexus, embrace the axillary artery, and then unite into one trunk. This descends the arm, at first outside, and then crossing to the inner side, of the brachial artery, to the bend of the elbow, over the brachialis anticus muscle. Then it passes between the two heads of the pronator radii teres muscle, and 184 ANATOMY. under the flexor snblimis digitorum, to become more superficial two inches above the wrist. Thence it passes under the annular ligament to the hand. No branches go from the median nerve till it reaches the fore- arm. Then it gives off the muscular, anterior interosseous, and pal- mar cutaneous branches. The muscular branches supply the superficial muscles in front Fig. 82. of the forearm, except the flexor carpi ulnaris. The anterior interosseous nerve goes to the deep muscles of the front of the forearm. The palmar cutaneous nerve arises low down and divides above the annu- lar ligament into an outer branch for the ball of the thumb, and an inner one for the palm of the hand. The median nerve, reaching the palm, outside of the flexor tendons, divides into an external and an internal branch. The former supplies the mus- cles of the thumb and forefinger ; the internal, the middle finger and part of the forefinger and third finger. Each of the five digital branches gives off a dorsal branch, which runs along the side of the back of a finger to its end. There it divides into a dorsal and a palmar branch, for the extremity of the finger. Ulnar Nerve, This is behind the median nerve at their origin, and is smaller. Going on the inner side of the axillary and brachial artery, at the middle of the arm it runs obliquely across to descend be- tween the olecranon process and the inner condyle of the humertis. It reaches the foramen between the two heads of the flexor carpi ulnaris mus- cle. Descending along the ulnar side of the forearm, it goes outside of the pisiform bone at the wrist, and, just below that bone divides into the super- ficial and deep palmar nerves. Besides these, its branches are, the articular, muscular, cutaneous, dor sal cutaneous, and carpal articular. NERVES OF THE FRONT OF THE FOREARM. 1. Median nerve. 2. Musculo-spiral or radial. 3. Ul- nar nerve. 4. Division of median nerve to the thumb, fore, middle, nnd radial side of ring finger. 5. Division of ulnar, to ulnar side of ring, and to little finger. MUSCULO-SPIRAL NERVE RADIAL NERVE. 185 The upper articular branches are several small ones for the elbow-joint. The two muscular branches pass off near the elbow to the flexor muscles. The cutaneous arises about the middle of the forearm, and sub- divides into superficial and deep cutaneous branches. The dorsal cutaneous passes, from about two inches above the wrist, backwards beneath the flexor carpi ulnaris to the ulnar side of the wrist and the inner side of the little finger and adjoining sides of the little and the third or ring finger ; communicating also with a branch of the radial nerve. The lower articular filaments go to the wrist. The superficial palmar terminal branch of the ulnar nerve sup- plies the skin on the inner side of the hand, and sends two digital branches; one to the ulnar side of the little finger, the other to the adjoining sides of the little and ring fingers. The deep palmar branch follows the course of the deep palmar arterial arch beneath the flexor tendons; and sends filaments to the small muscles of the hand. Musculo-Spiral Nerve. The musculo-spiral nerve is the largest one that goes off from the brachial plexus. It passes behind the axillary artery and down in front of the tendons of the teres major and latissimus dorsi muscles ; winds around the humerus with the superior pro- funda vessels, and then, on the outside of the arm, descends between the brachialis anticus and supinator radii longus to the front of the external condyle. There it subdivides into the radial and pos- terior interosseous nerves. Its branches are, besides these, the muscular and cutaneous. The muscular branches go to the triceps, anconeus, supinator longus, extensor carpi radialis longior, and brachialis anticus muscles. . The three cutaneous branches are, one internal and two exter- nal. They arise in or near the axillary space, and are distributed to the tegument, the lowest extending to the wrist. Radial Nerve. The radial nerve runs down on the front of the radial side of the forearm, two-thirds of its length, outside of the radial artery. Then it leaves that vessel, perforates the fascia outwards, and divides into an external and an internal branch. The former is small, and cutaneous in its distribution. The internal forms an arch on the back of the hand with the dorsal branch of the ulnar nerve. Then it gives off four digital nerves ; one to the ulnar side of the thumb, one to the radial side of the forefinger, a third to the adjoining sides of the fore and middle fingers, the fourth to the adjoining sides of the middle and ring fingers. 16* 186 ANATOMY. The posterior interosseous nerve pierces the snpinator radii brevis rnnscle, winds to the back of the forearm, and then passes down between the superficial and the deep layers of muscles to the middle of the forearm. Thence, over the interosseous ligament it reaches the back of the wrist ; and, having a ganglion- like enlarge- ment, gives off filaments from it to the wrist-joint. The branches of this nerve supply many of the muscles of the radial side and back of the forearm. Twelve Dorsal Nerves. The anterior branches of these, on each side, are the intercostal nerves. The posterior branches are smaller ; they divide into ex- ternal and internal ramifications. Their distribution is to the superficial and deep muscles of the back. Twelve pairs of cuta- ^neous branches go off, six above from the internal, and six from the external posterior dorsal nerves. Intercostal Nerves. There are twelve on each side. The upper six go only to the chest (except the first) ; the lower six supply also the walls of the abdomen. The nerves of both sets go forward in the intercostal spaces below the artery and veins as far as the anterior termina- tions of the intercostal spaces. Those of the upper set, near the sternum, cross the internal mammary artery, penetrate the in- tercostal and pectoralis major muscles, and become the anterior cutaneous thoracic nerves. The lower ones, anteriorly, pass behind the costal cartilages, and between the internal oblique and trans- versalis muscles, to supply the rectus abdominis muscle ; and af- terwards become cutaneous. Lateral cutaneous nerves go off from the intercostal nerves, half way between the spine and the sternum. The first intercostal nerve has no lateral cutaneous branch. That of the second is the inter costo-humeral nerve. Perforating the external intercostal muscle, it crosses the axilla to the inner side of the arm ; there becoming cutaneous, and communicating with the cutaneous nerves of the arm. Sometimes the third inter- costal nerve also gives off an intercostal humeral branch. The^rs^ dorsal nerve has but a small intercostal branch ; its anterior trunk mainly going into the brachial plexus. The last dorsal nerve has a very large lateral cutaneous branch ; reaching, in its distribution, as far as the surface over the hip- joint. Five Lumbar Nerves. The anterior branches of these, besides communicating with the sympathetic, send off muscular branches. Those of the first four lumbar nerves form the lumbar plexus. That of the Jifth, joins SACRAL AND COCCYGEAL NERVES. 1ST the sacral plexus, in a trunk with the anterior branch of the sacral nerve (lumbo-sacral nerve). The posterior lumbar branches subdivide into external and in- ternal ; and are then distributed to the muscles of the lumbar region. Lumbar Plexus. This is located upon or in the psoas magnus muscle, near the transverse processes of the vertebrae, on each side. Its branches are, the ilio-hypogastric, ilio-inguinal, genito- crural, external cuta- neous, obturator, accessory obturator, and anterior crural nerves. Of these, the ilio-hypogastric, ilio-inguinal, and part of the genito-crural nerves are distributed to the lower abdominal walls. The rest of the genito-crural and the external cutaneous, obturator, accessory obturator, and anterior crural nerves, supply the fore part of the thigh and the inner side of the leg. Anterior Crural Nerve. This is the largest branch of the lumbar plexus. It sends mus- cular branches to the iliacus interims and pectineus muscles, and to all the muscles on the anterior part of the thigh ; also, cutane- ous and articular branches. In its course, the anterior crural nerve goes down between the psoas magnus and iliacus internus muscles, beneath Poupart's liga- ment, to the thigh ; there dividing into an anterior cutaneous and a posterior muscular portion. From the anterior part, it gives off the middle cutaneous, internal cutaneous, and long saphen- ous nerves, from the posterior part, muscular and articular branches. The long or internal saphenous nerve is the largest of the cutane- ous branches. It lies outside of the femoral artery from its passage beneath the sartorius muscle to the opening in the lower part of the adductor magnus. Thence it descends vertically along the inner side of the knee ; penetrates the deep fascia between the tendons of the sartorius and gracilis muscles, and, becoming sub- cutaneous, goes down the inner side of the leg with the internal saphenous vein. In the lower third of the leg it divides into two terminal branches. One goes along the tibia to the inner mal- leolus ; the other is distributed to the inner side of the foot, as far as the great toe. Sacral and Coccygeal Nerves. These are six on each side ; the last one called coccygeal. The collection of their long roots together at the lower end of the spinal marrow makes the cauda equina. The lumbo-sacral nerve and the anterior branches of the three upper, and part of the fourth sacral nerve, form the sacral plexus. 188 ANATOMY. Sacral Plexus. This gives off from within the pelvis on each side the following branches : muscular, superior gluteal, pudic, lesser sciatic, and great sciatic nerves. The muscular branches go to the pyriformis, obturator interims, gemelli, and quadratus femoris muscles. The superior gluteal nerve passes with the gluteal bloodvessels through the great sacro-sciatic foramen ; and then divides into a superior and an inferior branch. The former goes to the glutei muscles; the latter also to the tensor vaginae femoris. The pudic nerve leaves the pelvis through the great sacro-sciatic foramen, crosses the spine of the ischium, and then re-enters the pelvis by the lesser sacro-sciatic foramen. It goes with the pudic vessels upwards and forwards, and divides into the perineal and dorsalis penis nerve. A previous branch of it is the inferior hemorrhoidal nerve ; which goes to the sphincter aui muscle and the integument around the anus. The perineal nerve lies below the pudic artery, and divides into cutaneous and muscular branches ; the cutaneous, into an anterior and a posterior branch. The dorsal nerve of the penis runs with the pudic artery along the ramus of the ischium, and then penetrates the suspensory liga- ment of the penis and passes with the dorsal artery of the penis to the glans. In the female, the superior division of the pudic nerve goes to the clitoris ; the inferior, to the external labia and the perineum. The small sciatic nerve is distributed to the skin of the perineum, the back of the thigh, and the glutens maximus muscle. Its branches are muscular or inferior gluteal, and internal and ascend- ing cutaneous branches. Great Sciatic Nerve. This is the largest nerve in the body. Passing out through the great sacro-sciatic foramen it goes down between the tuberosity of the ischium and the trochanter major to the back of the thigh, and, at its lower third, divides into the internal and external pop- liteal nerves. Before dividing, it sends off articular and muscular branches ; the first to the hip-joint, the last to the flexor muscles on the back of the thigh. The internal popliteal nerve passes down through the popliteal space, back of the knee, to the lower part of the popliteus muscle ; then, with the artery, to become, under the arch of the soleus mus- cle, the posterior tibial nerve. Its branches, before this, are the articular, muscular, and external or short saphenous nerves. The articular branches go to the knee-joint. The muscular, to GREAT SCIATIC NEEVE. 189 Fig. the muscles of the calf of the leg. The external or short saphenous nerve descends between the heads of the gastrocnemius muscle, perforates the fascia at the middle of the leg, and, with a branch (communicating peroneal nerve) from the external popliteal nerve, goes down the outer margin of the tendo Achillis ; then, with the external saphenous vein it winds around the external malleolus and is distributed to the skin on the outer side of the foot. The posterior tibial nerve descends with the posterior tibial vessels to the space between the internal malleolus and the heel ; there dividing into the external and internal plantar nerves. Above, it lies to the inner side of the artery ; soon, how- ever, it crosses it, and keeps to its outer side to the ankle. Its branches are mus- cular and plantar cutaneous; besides the two terminal branches, external and inter- nal plantar. The muscular ones go to the deep muscles of the leg ; the plantar cutaneous, to the heel and the sole of the foot. The internal plantar nerve goes with the internal plantar artery along the inner side of the foot. Opposite the bases of the metatarsal bones it gives off' four ter- minal digital branches ; communicating also with the external plantar nerve. Be- fore these, it gives off cutaneous muscular t tarsal and metatarsal articular branches of the foot. The external plantar nerve supplies the little toe and half of the fourth toe, as well as some of the muscles of the foot. The external popliteal or peroneal nerve descends obliquely in the popliteal space near the margin of the biceps muscle to the fibula. An inch below the head of that bone it perforates the peroneus longus muscle and divides into the anterior tibial and musculo- cutaneous nerves. Before dividing, it gives off" two articular branches to the knee, and two or three cutaneous branches to the back and outer side of the leg. The anterior tibial nerve runs obliquely forwards under the ex- tensor digitorum, joining the anterior tibial artery, on its outside, above the middle of the leg. Then descending with the artery to the front of the ankle, it divides into an internal and an external branch. Before this, it gives off some muscular branches to the leg. POSTERIOR TIBIAL NERVE. 190 ANATOMY. The internal branch goes with the dorsal artery of the foot along the inner side of the latter, and divides into two branches for the adjoining sides of the great toe and the second toe. The external or tarsal branch of the anterior tibial nerve goes outwards across the tarsus, and forms a ganglion-like enlargement ; from which proceed branches to the extensor brevis of the toes and the tarsal and metatarsal articulations. The musculo- cutaneous branch of the external popliteal or peroneal nerve passes forwards to penetrate the deep fascia at the lower third of the leg, in front and on the outer side. Then it divides into an internal and an external branch ; having, first, given off some muscular and cutaneous Fig. 84. branches. The internal of these branches goes in front of the ankle and along the dor- sum of the foot to the great toe, and the adjacent sides of the second and third toes ; also supplying the skin over and above them. It communicates with the internal saphenous nerve, as well as with the anterior tibial nerve. The external terminal branch of the musculo-cutaneous nerve is larger. It runs along the outside of the dorsum of the foot, to the adjacent sides of the third, fourth, and fifth toes, and to the integument of the outer ankle, and outer side of the foot. SYMPATHETIC NERVE. This, the gangl ionic system of physio- logists, consists of a series of ganglia, connected together, and communicating with the spinal marrow and various organs and vessels, by cords of gray and white nerve filaments. The ganglia of the two sides meet above, at the ganglion of Ribes, upon the anterior communicating artery of the brain. Below, they converge to the ganglion impar in front of the coccyx. The ganglia or centres of the sympathetic system are numerically as follows: four cephalic; three cervical ; twelve dorsal; four lumbar; five sacral; ANTERIOR T, B rAt NERVE.-I. d COCC yaeal ganglion. Their iMusculo-cutaneous nerve. 2, 2. yy . . Anterior tibial nerve. branches are: 1. Communicuting CEPHALIC GANGLIA. 191 branches between the ganglia. 2. Branches connecting the gan- glia with the cephalic or spinal nerves. 3. Branches distributed to the arteries, to the viscera, and to the thoracic, abdominal and pelvic gangia and plexuses. Cephalic Ganglia. Ophthalmic, ciliary, or lenticular ganglion. This is a flattened vesicular mass of about the size of a pin's head, at the back of the orbit of the eye, between the optic nerve and the external rectns muscle. Its communicating branches are three: one with the nasal branch of the ophthalmic nerve, or first branch of the fifth pair. Another, with a branch of the third or motor ocnli nerve. The other connects with the cavernous plexus of the sympathetic. Its branches of distribution are the short ciliary nerves, ten or twelve, going to the ciliary muscle and iris. Spheno-palatine, or MeckeVs ganglion. This is the largest of those of the head. It is located in the spheno-maxillary fossa; and has a somewhat triangular shape. Its roots (as some anato- mists call the communicating filaments) are, one from the facial (portio dura of seventh pair) through the vidian ; one from the fifth ; and one from the carotid plexus of the sympathetic, through the vidian nerve. Its small ascending branches go into the orbit by the spheno- maxillary fissure, arid supply its periosteum. The palatine branches of this ganglion are the anterior, middle, and posterior palatine nerve. The anterior goes down through the posterior palatine canal, out by the posterior palatine foramen upon the hard palate, and passes forwards in a groove of the latter almost to the incisor teeth. In the canal, it sends off inferior nasal filaments, which go to ramify in the middle meatus and the turbinated bones. The middle palatine nerve goes through the same canal as the above, to the posterior palatine foramen, giving off branches to the tonsil, soft palate, and uvula. The posterior palatine nerve goes through the small posterior palatine canal, emerging behind the posterior palatine foramen ; to be distributed to the soft palate, uvula, and tonsil. The internal branches of Meckel's ganglion are the anterior superior nasal and the naso-palatine nerves. The former are four or five ; they enter the nasal fossa through the spheno-palatine foramen, and supply its mucous membrane. The naso-palatine nerve (nerve of Cotunnius) enters the nasal fossa with the above, goes inwards to the septum narium, then downwards and forwards along the septum to the anterior palatine foramen. It goes down to the roof of the mouth, where those of the right and left sides join, and supply the mucous membrane. Posterior branches of the spheno-palatine ganglion are, the 192 ANATOMY. Vidian nerve and the pharyngeal or pterygo-palatine nerve. The Vidian nerve runs through the Vidian canal to the foramen lace- rum, and divides into the large petrosal and the carotid branches. The large petrosal nerve passes beneath the ganglion of Casser in a groove of the petrous part of the temporal bone ; then through the hiatus Fallopii into the aqueductus Fallopii, connecting with the ganglionic enlargement of the facial nerve. The carotid branch of the Vidian enters the carotid canal of the temporal bone, outside of the artery, and joins the carotid plexus. A ganglionic enlargement upon it is called the carotid ganglion, or ganglion of Laumonier. The pharyngeal nerve goes through the pterygo-palatine canal with the artery of that name, to the mucous membrane of the pharynx. Otic ganglion (of Arnold). This is a small, flattened, oval gan- glion, located below the foramen ovale, upon the third branch of the fifth nerve. The cartilaginous portion of the Eustachian tube is at its internal side. It communicates with the third branch of the fifth pair, with the sympathetic plexus around the middle meningeal artery ; and with the glosso-pharyngeal of the eighth, and the facial of the seventh pair, through the small petrosal nerve. Branches from this ganglion are distributed to the tensor tympani and tensor palati muscles. Submaxillary ganglion. This is small and circular, located near the posterior margin of the mylo hyoid muscle. It is connected with the gustatory nerve, with the chorda tympani, and with the nervi molles of the sympathetic which surround the facial artery. Branches go from it, five or six in number, to the mucous mem- brane of the mouth, and to the submaxillary gland and its duct. Cervical Ganglia. These are three on each side : the superior, middle, and inferior, ganglia of the neck. The superior is largest. It is opposite to the second and third, sometimes fourth cervical vertebra. In front of it are the internal carotid artery, jugular vein, and glosso-pharyngeal nerve; behind it, the rectus capitis anticus major muscle ; outside of it, the pneumogastric nerve. Its branches are superior, inferior, external, internal, and anterior. The superior branch runs into the carotid canal, and divides into an inner and an outer branch, both distributed to the internal carotid artery. On the inner, the cavernous plexus is formed'; on the outer branch, the carotid plexus. The inferior branch of the first cervical ganglion connects with the second or middle ganglion. The external branches are numerous. They communicate with the cephalic nerves, and with the four upper spinal nerves. CARDIAC PLEXUSES. 193 The internal ones are three : the pharyngeal and luryngeal branches, and the superior cardiac nerve. The last-named, on the right side, goes to the deep cardiac plexus ; on the left side, to the superficial cardiac plexus. The anterior branches of the same ganglion (nervi niolles) form plexuses about the external carotid artery and its branches. The middle cervical ganglion is the smallest of the three. It lies opposite to the fifth cervical vertebra, close to the inferior thyroid artery. Its superior branches go up to the superior ganglion ; its infe- rior ones, down to the inferior ganglion. External branches pass to the fifth and sixth spinal nerves. Its internal branches are the thyroid nerves, to the thyroid artery and gland, and the middle cardiac nerve. This last nerve goes to the deep cardiac plexus. The inferior cervical ganglion lies near to the neck of the first rib. Its superior branches go up to the middle ganglion ; its inferior ones, down to the first thoracic ganglion. Among them is the inferior cardiac nerve, which joins the deep cardiac plexus. Some external branches connect with the seventh and eighth spinal nerves; others form a plexus around the vertebral artery. Cardiac Plexuses. These are the superficial cardiac plexus, the deep cardiac plexus, and the anterior and posterior coronary plexuses. The superficial cardiac plexus is beneath the arch of the aorta, in front of the right pulmonary artery. It is supplied by the left superior cardiac nerve, the left, and sometimes the right, inferior cardiac branches of the pneumogastric, and connecting branches from the deep cardiac plexus. It sends filaments to form the anterior coronary plexus, and some to the left anterior pulmonary plexus. The great or deep cardiac plexus lies in front of the bifurcation of the trachea, behind the arch of the aorta. It is formed by the cardiac nerves already described, and by the cardiac branches of the pneumogastric and recurrent laryngeal nerves. This plexus supplies the posterior coronary plexus and part of the anterior coronary plexus ; sending filaments also to the auricles of the heart and the pulmonary plexuses. The anterior coronary plexus lies with the right coronary artery on the anterior surface of the heart. The posterior coronary plexus embraces the branches of the coronary artery upon the back of the heart Beneath the endocardium Valentin and Robert Lee have demonstrated the existence of fine nervous ramifications, some within the substance of the heart, having many ganglia upon them. 17 194 ANATOMY. Fig. 85. Thoracic Ganglia. These are usually twelve ; placed on each side of the vertebral column, against the heads of the ribs. They have, each, two ex- ternal branches, connecting with the dorsal spinal nerves. From the upper six ganglia, small internal branches go to the thoracic aorta and its branches ; the third and fourth give filaments also to the pulmonary plexus. Internal branches pass from the six lower thoracic ganglia to unite and form \\\Q great splanchnic, lesser splanchnic and the renal splanchnic nerves. The great splanchnic nerve is whiter than the ordinary gangl ionic nerves. It goes obliquely down- wards and inwards to penetrate the diaphragm, and enter the semilu- nar ganglion. The lesser splanchnic nerve also perforates the diaphragm, and con- nects with the cceliac plexus. The renal or smallest splanchnic nerve goes from the lowest thoracic ganglion through the diaphragm to join the renal plexus, as well as the lower part of the coeliac plexus. THORACIC GANGLIA.-^ Aorta, b. First rib. c. Eleventh rib. 1. First thoracic ganglion. 2. Last thoracic ganglion. 3. Great splanchnic nerve. 4. Lesser splanchnic nerve. 5. Renal splanchnic. 6. Part of brachial plexus. Solar Plexus. This name is given to a dense network of nerves and ganglia, be- hind the stomach, and front of the aorta. It is 'the termination of the great splanchnic nerves, part of the lesser splanchnic, and the right pneumogastric nerv. Branches from it form plexuses which surround the branches of the abdominal aorta. The semilunar ganglia, one on each side, are the largest ganglia in the body. They lie very near to the supra-renal capsules and the coeliac axis artery. The plexuses connected with or proceeding from the solar plexus are named as follows : phrenic, coeliac, gastric, hepatic, splenic, supra-renal, renal, superior mesenteric, spermatic, and inferior mesenteric plexuses. They accompany the arteries of corresponding names. The aortic plexus is also formed by branches of the solar LUMBAR GANGLIA PELVIC GANGLIA. 195 and renal plexuses, receiving some filaments from the lumbar ganglia. Lumbar Ganglia. These are four, lying in front of the spinal column. Superior branches connect each with the ganglion above it; inferior ones with that next below ; and external branches, with the lumbar spinal nerves. Internal branches go in part to the aortic plexus ; some to form the hypogastric plexus over the promontory of the sacrum. Pelvic Ganglia. Of these there are four or five in front of the sacrum. They ap- proach below, and unite in the ganglion impar on the front of the coccyx. The distribution of their branches closely resembles that of those of the lumbar ganglia. The hypogastric plexus is formed by nerves from the two upper pelvic ganglia, the lumbar ganglia, and aortic plexus. Its branches are sent to the pelvic viscera. The inferior hypogastric or pelvic plexus is an extension down- wards of the above; supplied from the three or four lower pelvic ganglionic branches on each side, and some filaments directly from the ganglia. It lies by the side of the rectum and bladder in the male ; by the rectum, bladder, and vagina in the female. From it branches go to all the pelvic viscera, with the branches of the iliac artery. Back of it, from its branches is formed the inferior hemorrhoidal plexus. In front of it, the vesical plexus. Below it, the pros- tatic plexus. The nerves from this last are large, and pass in the male to the vesiculas seminales, prostate, and erectile structure of the penis. The large and small cavernous nerves are the principal branches. In the female, the vaginal plexus is below the pelvic or inferior hypogastric pelvis. It supplies the vagina. From the hypogastric plexus pass off the nerves that supply the uterus. In the substance of that organ, as in that of the heart, Dr. Robert Lee has shown the existence of nervous filaments and ganglia. 196 ANATOMY. CHAPTER X. ORGANS OF SPECIAL SENSE. THE EYE. THE eyeball is nearly globular. Its coats are the conjunctiva, sclerotic, choroid, and retina. The transparent refracting media- are the cornea, aqueous humor, crystalline lens, and vitreous humor. Interior parts, connected with the choroid coat, are, also, the iris, ciliary ligament and muscle, and ciliary processes . Appen- dages of the eye are the eyelids, eyelashes, eyebrows, lachrymal gland, Meibornian glands and ducts; muscles, nerves, and blood- vessels. The conjunctiva is a mucous membrane which lines the eyelids and is reflected over the front part of the sclerotic and the cornea. Fig. 86. SECTION OP THE EVE 1. Sclerotic coat. 2. Cornea. 3. Choroid coat. 4. Ciliary liga- ment. 5. Ciliary processes. 6. Iris. 7. Pupil. 8. Retina. 9. Canal of Petit. 10. Ante- rior chamber containing the aqueous hnmor. 11. Posterior chamber. 12. Lens inclosed in its capsule. 13. Vitreous huinor in the hyaloid membrane. 14. Sheath of the hyaloid membrane. 15. Neurilemma of the optic nerve. 16. Arteria centralis retina}. Near the inner angle of the eye it forms a fold called plica semi- lunaris. The caruncvla lacrymalis is at the inner side of this ; it is a small, reddish, conical enlargement, consisting of follicles. The sclerotic, or hard coat of the eye, is fibrous in structure. Externally, it is white ; internally, brownish, and marked with grooves for the ciliary nerves. The muscles of the eyeball are THE EYE. 19t inserted into it. The optic nerve perforates it. Tn front, the cornea is continuous with its edge ; being set into it as a watch- glass in its case. The cornea projects anteriorly, constituting about one-sixth of the ball of the eye. It is most prominent in early life. Its proper tissue is fibrous, covered in front and behind by elastic laminae. No capillaries extend into the cornea. The choroid coat is beneath the sclerotic. It has three layers. The external layer consists of the branches of the short ciliary arteries and, in greater number, the curved veins called vense vorti- cosce. Among the vessels are stellate pigment-cells. The middle layer (tunica Ruyschiana) is a plexus of fine capillaries from the short ciliary arteries. The internal pigmentary layer consists of six-sided pigment-cells, with nuclei and color-granules within them. The ciliary processes are folds of the anterior margin of the choroid coat, making a circle around the edge of the crystalline lens, behind the iris. They are from sixty to eighty in number. Their vessels are larger than those of the choroid coat, and are mainly longitudinal. The iris is a circular curtain, suspended behind the cornea in the aqueous humor ; with a central aperture, the pupil. Its circum- ference is connected in part with the choroid, and, outside of that, by the ciliary ligament, with the sclerotic and cornea at their junction. It is composed of a fibrous stroma or central tissue, with commingled muscular fibres. These are the radiating mus- cular fibres, reaching to the circumference, and the circular ones, surrounding the pupil. Pigment-cells are also contained in it, giving the different colors to the eyes of different persons. Behind, the iris is purple ; this surface is called the uvea. The ciliary ligament is a narrow circle around the circumference of the iris, at the place of its union with the choroid, sclerotic, and cornea. A minute canal exists where it joins the sclerotic, the sinus circularis iridis. The ciliary muscle is a circular band of unstriped fibres, longi- tudinal in direction, connecting the junction of the sclerotic and cornea with the choroid coat. Its action is upon the ciliary pro- cesses, and perhaps upon the lens. The retina is the innermost coat of the eye. Outside of it is the choroid ; within it, the vitreous humor. The optic nerve enters it a little to the inner side of the centre of the ball. Anteriorly it terminates a little behind the ciliary ligament, in a jagged edge, the ora serrata. Exactly in the centre of its posterior part, in the axis of the eye, is the yellow spot of Scemmering, the point of most perfect vision. The central artery of the retina enters through the centre of the optic nerve. This point is destitute of vision. The retina consists of three (Kb'lliker says four) layers: 1, external, Jacob's membrane, layer of rods and cones; 2, middle, If* 198 ANATOMY. Fi g- 87- granular layer; 3, internal layer; expansion of the optic nerve into a network, and arrangement of nerve-cells. A very delicate membrane, membrana limitans, separates the retina from the vi- treons humor. The aqueous humor is divided by the iris into an anterior and a posterior chamber The anterior is the larger. This humor is, as its name indicates, of a watery consistence. The crystalline lens lies behind the posterior chamber of the aqueous humor, and in front of the vitreous humor. It is a double convex transparent body, inclosed in an elastic membra- nous capsule. It measures about one-third of an inch across, and one-fourth of an inch from before backwards. The posterior surface is the most convex. In structure, the lens is formed of a number of concentric laminae, which may be separated by boiling or im- mersion in alcohol. By the same means a partition of the lens may be shown into three triangular segments. More minutely, the laminaB consist of parallel fibres with wavy margins. The suspen- sory ligament of the lens is a thin membrane between the anterior TRANSVERSE SECTION OF THE EYE.! . Edge of sclerotic, choroid, and retina. 2. Pupil. 3. Iris. 4. Ciliary processes. 5. Border of retina. Fig. 88. Fig. 89. Crystalline lens divided. surface of the lens and the anterior margin of the re- tina. Posteriorly, this is separated from the hyaloid membrane by a space called the canal of Petit. MUSCLES OP THE EYEBALL. 1. Fragment of the sphenoid bone. 2. Optic nerve. 3. Globe of the eye. 4. Levator palpebne muscle, b. Superior oblique muscle. 6. Its cartilaginous pulley. 7. Its reflected tendon. 8. Inferior oblique muscle. 9. Superior rectus muscle. 10. Internal rectus. 11. External rectus. 12. Ex- tremity of the external rectus. 13. Inferior rectus muscle. 14. Sclerotic coat. APPENDAGES OF THE EYE THE EAR. 199 The vitreous humor forms about four-fifths of the whole eyeball. It is a transparent jelly-like material, inclosed in the hyaloid membrane. The arteries of the eye are the long, short, and anterior ciliary arteries, and the central artery of the retina. The nerves of the Fig. 90. eye are the optic, long ciliary, and short ciliary nerves. Appendages of the Eye. Each eyelid (palpebra) is com- posed of the following structures : skin, connective or cellular tissue, orbicularis oculi muscle, tarsal cartilage, Meibomian glands, and conjunctiva, The tarsal carti- lages are two thin elongated strips of fibro-cartilage along the mar- gin of the lids. The tensor tarsi muscle is attached to their inner ends. The Meibomian glands are about thirty in number for the upper lid ; rather less in the lower. They are about as long as the width of the tarsal cartilages. Each has a minute duct opening on the margin of the eyelid. The eyelashes are short, thick, curved hairs, in a double, or sometimes triple row on each lid; the convexity of the upper ones beiug downwards, and of the lower ones upwards. The lachrymal gland lies in a small fossa within the orbit, at its upper and outer, anterior part. It is oval, and about the size of an almond. Six or seven ducts carry tears from it to open through the conjunctiva, over the globe of the eye. Moisture being thus diffused over the ball, collects near the edges of the lids, and passing between the tarsi in the groove which they make when closed, or along the lower one when open, enters the puncta lacry- malia, near the corner of the eye. From these, two minute ca- naliculi convey the secretion (unless when, as in weeping, it is so profuse as to overflow) into the lachrymal sac. This is an enlarge- ment at the upper part of the nasal duct; which duct or tube lies in a bony canal, three-quarters of an inch long, formed by the lachrymal (os unguis), superior maxillary, and inferior turbinated bones. It opens into the inferior meatus of the nose. LACHRYMAL CANALS. 1. Puncta lacry- malia. 2. Cul-de-sac at the orbital end of the canal. 3. The course of each canal, t, 5. The saccus lacryrnalis. 6. Ductus ad nusum. 200 ANATOMY. THE EAR. External Ear. The expanded part of the ear is the pinna, or auricle ; the auditory opening (and canal) is the external meatus. The pinna consists of cartilage covered by skin. Its external prominent rim is the helix. Parallel with and in front of this, but dividing above, is the antihelix. Within the inclosure of the latter is a cavity of some size, the concha. In front of this, over the meatus, is the pointed projection, the tragus ; and oppo- site to the latter, a smaller one, the anti-tragus. The softer lowest part of the ear is called the lobule. The external meatus or auditory canal is about an inch and a quarter long, and directed forwards and inwards, slightly curved. At its end or bottom is the membrana tympani. The meatus is formed partly of cartilage and partly of bone, and is lined with a thin skin. Near the orifice are hairs and sebaceous glands ; and, farther in, the ceruminous glands, which secrete the ear-wax. Middle ear, or tympanum. Being within the petrous portion of the temporal bone, the cavity of the tympanum is separated from the external raeatus by the membrana tympani. It communicates with the pharynx by the Eustachian tube. Within it are the ossi- cles or small bones of the ear ; malleus, incus, orbicular, and stapes. The malleus or hammer-bone has a head, neck, handle or manu- brium, and two processes. The head is the oval upper extremity, which connects with the incus. The manubrium is vertical in position, and is attached along its margin to the membrana tympani. The pro- cessus gracilis is long and delicate ; it gives origin to the laxator tympani muscle. The processus brevis or short process gives origin to the tensor tympani muscle. The incus or anvil-bone has an irregular four-sided body, and a long and short process. The body joins with the malleus. The long OSSICLES OF T.-K EAR -a. Malleus, 8g connectg wilh the Q& orbicu . its head. h. Handle of malleus. 0. r Incus, o. Orbiculare. c. Stapes. The stapes or stirrup-bone has very much the shape of a stirrup. By its head it is attached to the orbiculare ; by its foot to i\\vfenestra ovalis of the vestibule. To its neck is connected the stapedius muscle. The orbiculare is a very small round bone, between the long process of the incus and the head of the stapes. These bones are all united by ligaments, admitting of slight movement. Besides thefenestra ovalis, there is another aperture, thefenestra THE EAR. 201 Fig. 92. rotunda, from the tympanum into the 'cochlea of the internal ear. The latter is closed by a membrane. The muscles of the tympanum have been already named ; tensor tympani, laxator tympani, and stapedius. The first of the three is the largest. It draws the membrana tympani inwards, making it more tense. The laxator reverses this action. The chorda tympani nerve leaves the facial to enter the tympanum, and crosses its cavity to an opening near the Glaserian fissure. Several other nerves enter and communicate in the tympanum. Internal ear, or labyrinth. This is composed of the vestibule, semi-circular canals, and cochlea. The vestibule is the middle por- tion. On its outer wall are the fenestra ovalis and fenestra rotunda. In its inner wall is the foramen of the aqueduct of the vestibule, going to the back part of the petrous portion of the temporal bone. In front is a large opening, communi- cating with the cochlea; apertura scalce vestibuli cochleae. Behind, five orifices open from the vestibule into the semi-circular canals. The three semi-circular canals are above and behind the vestibule. They are unequal in length and different in direction ; two being vertical and one horizontal. The cochlea is shaped somewhat like a snail-shell. It is anterior to the vestibule. It consists of the modiolus or columella, which is its central axis, and a spiral canal wound around this, with the lamina spiralis (partly osseous and partly cartilaginous), contained within the canal. The spiral canal has two turns and a half. The interior is divided into two equal scalae or staircase like passages (scala tympani and scala ves- tibuli, by the delicate lamina spiralis; upon which the nerve fila- ments of the auditory nerve are spread out. The terminations of that nerve are also distributed to the vestibule and semi-circular canals. The whole inner surface of the bony labyrinth is lined by a fibro-serous periosteal tissue. In the vestibule and semi-circular canals, it separates the osseous from the membranous labyrinth ; its fibrous coat being attached to the bone, and its free serous layer to the membranous interior structure. In the cochlea, it covers both surfaces of the osseous zone of the lamina spiralis and VIEW OP THE EAR. 1. The opening into the ear at the bottom of the concha. 2. Meatus auditorius externus. 3. Membrana tympani. 4. Malleus. 5. Stapes. 6. Labyrinth. 202 ANATOMY. then forms the membranous zone (zona Vahah-ce}, or continuation of the same. The liquor Cotunnii or perilymph is the fluid secreted within the periostea! double layer thus described. The membranous labyrinth is the internal duplicate of the vesti- bule and semi-circular canals. The vestibular portion of it is formed into two sacs, the utricle and the saccule. The endolymph, or liquor Scarpce, is the fluid contained within the labyrinth. The otoliths or otoconia are two small round collections of crystals of carbonate of lime, surrounded by fibrous tissue, in the vestibule. THE NOSE. Five cartilages, with the bony structures (nasal bones and pro- cesses of the superior maxillary bones) make up the framework of this organ ; two upper and two lower lateral cartilages, and the nasal septum. The nasal fossa or cavities of the nostrils are lined by the pituitary or Schneiderian mucous membrane. It is covered by epithelium, tessellated at the upper part and near the aperture of the nares, but ciliated through the rest of its extent. The olfactory .nerve is distributed to it. Mucous glands abound in it. The passages of the nares or nostrils are divided in front into the superior, middle, and inferior meatus. The posterior nares open into the pharynx. Besides the olfactory, a number of nerves reach the nasal mucous membrane ; principally branches of the fifth pair, already described. CHAPTER XI. ANATOMY OF HERNIA. Inguinal Hernia (see Fig. 67). Dissecting off the skin and superficial fascia from the groin, the lower portion of the external oblique muscle is exposed. The diverging fibres of this muscle, just above and outside of the pubes, give passage to the spermatic cord; in the female, the round ligament. This natural opening is the external abdominal ring. It is, rather, a triangular aperture; the inner column of which is that part of the tendon of the muscle which goes to the symphysis pubis ; and its outer column, a portion or reflection of Pouparfs ligament ; i. e , the tendinous margin of the external oblique muscle, extending from the anterior superior ANATOMY OF HERNIA. 203 spine of the ilium to the pubes. Direct or ventral hernia occurs immediately through the external ring; carrying over it the com- mon tendon of the internal oblique and transversalis. The inguinal canal leads from the external ring, downwards, forwards, and inwards, about an inch and three-fourths, to the in- ternal abdominal ring. Along it the spermatic cord passes to and through the internal abdominal ring. This is an opening in the fascia transversalis through which the cord enters, or, more properly, emerges from the abdomen, on its course to the testicle. The fascia gives a fibrous investment to the cord which continues to the testis ; this is i\\Q fascia propria. As the cremaster muscle covers the cord, as a " carrying down" of fibres of the internal ob- lique, a protruding knuckle of intestine, in inguinal hernia, has the following coverings: sfcin, superficial fascia (inter columnar fascia, from the external ring), cremaster muscle, fascia propria, and peritoneal coat or sac. The epigastric artery lies on the inside of oblique hernia, i. e., that through the inguinal canal. In direct or ventral hernia it is outside of the hernial tumor. Femoral Hernia. This occurs beneath Poupart's ligament, at the place of transit of the femoral vessels from the groin. Between the vessels and the pubes is a space through which the intestine escapes. It then protrudes farther by the saphenous opening, by which the internal saphenous vein joins the femoral vein. Over that opening is the cribriform fascia ; so called from its having a number of small perforations. The curved margin, by which, at the saphenous opening, the fascia lata, the thigh doubles or dips in, is sometimes called the falciform border. The crural arch is between Poupart's ligament and the pelvis. Under it, besides the iliacus internus and psoas muscles, pass the anterior crural nerve, femoral artery, and femoral vein. To the inner side of the latter is the crural ring. Gimbernat's ligament is a triangular reflection and expansion of the outer column of the external ring; that is, of the insertion of the external oblique muscle, attached to the lima pectinea of the crest of the pubes ; and directing a concave border towards the femoral vessels. The part of this border turned most directly to the vessels is Hey's ligament. The vessels, as they escape from the pelvis, receive a funnel-shaped fascial envelope the crural canal or sheath of the femoral vessels. A femoral hernia, therefore, has, as its coverings, the skin, su- perficial fascia, cribriform, fascia, sheath of the vessels (septum crurale, of fibrous tissue from the margin of the crural ring), and peritoneal sac. When, in the descent of the testicle in the process of development, the intestine enters the canal with it, the peritoneum over it not being obliterated, it forms congenital inguinal hernia. 204 ANATOMY. Umbilical and other forms of hernia require no special ana- tomical description here. The student is, however, advised not to be satisfied, in regard to the surgical anatomy of hernia, without repealed demonstrations or dissections. CHAPTER XII. THE PERINEUM. THIS region lies between the tnberosities of the ischia ; with the arch of the pubes in front, and the coccyx behind it. In and ARTERIES OF THE PERINEPM. 1. Penis. 2. Accelerators urinae muscles. 3. Erector penis. 4. Anus. 5. Raraus of ischium and pubes. 6. Tuberosily of ischiuin. 7. Leaser sacro-sciatic ligament. 8. Coccyx. 9. Internal pudic artery. 10. Inferior heniorrhoidiil branches. 11. Superficial perinei artery. 12. The same. 13. Artery of the bulb. 14. Terminal branches of the pudic artery. beneath the two layers of the superficial perineal fascia, are several vessels and nerves. The inferior or external hemorrhoidal artery is a branch of the internal pudic artery, leaving it, behind the tuberosity of the ischium, to go to the levator and sphincter ani. Farther forward, the internal pudic gives off the superficial perineal artery. Curving upwards to the ramus of the pubes, it runs obliquely forwards to terminate in the scrotum. THE PERINEUM. 205 The transversalis perinei artery goes off from this at a right angle, parallel with the transversus perinei muscle, to the sphincter ani. The artery of the bulb leaves the pudic to enter the corpus spon- giosum at its posterior margin. Sometimes it is a branch of the superficial perineal artery. The internal pudic artery is an important branch of the internal iliac. It goes out by the great sacro-sciatic foramen, crosses the spine of the ilium, re-enters the pelvis through the lesser sacro- sciatic foramen, and, reaching the ramus of the ischium, au inch in front of its tuberosity, runs beneath its edge to the symphysis pubis. There, as the arteria dorsalis penis, it goes on to end at the glans. Nerves of the perineal region are the internal pudic nerve, perineal cutaneous nerves, and their branches. Muscles of the same part are, besides the sphincter and levator ani, the transversus perinei, erector penis, and accelerators urince muscles. The transversus perinei muscle is a small bundle of fibres, passing across from the tuberosity of the ischium to the middle line, when it meets its fellow. The erector penis goes from the tuberosity and ramus of the penis. The accelerators urinse arise from the perineal centre, and, by diverging fibres, surround the basal portion of the penis. The triangular ligament is a portion of the deep perineal fascia, occupying the space under the arch of the pubes. Between its two layers are Cowper's glands. Through it the membranous portion of the urethra passes. The external pudic arteries and arteries of the bulb are, for part of their course, included within it. 18 A MANUAL OF PHYSIOLOGY CONTENTS. PAGE DEFINITIONS ........... 213 PART L GENERAL PHYSIOLOGY. CHAPTER I. ORGANIC MATTER. Organic Products 215 Organizable Principles ......... 215 Albumen, 215 Gelatin, 215 Ostein, 215 Chondrin, 215 Kera- tin, 215 Neurin, 215 Fibrin, 216 Musculin, 216 Globulin, 216 Casein, 216 Pulmonin, 216 Mucosin, 216 Haeinatin, 216 Melanin, 216 Fatty Principles, 216. CHAPTER II. ORGANIC FORCES. Vital Force 217 CHAPTER III. ORGANIC FORMS. Blood 218 Chyle 221 Lympli 221 Elementary Solid Forms 221 Cells 222 Fibres and Membranes 225 Tissues 226 Connective, 226 Fibrous, 226 Elastic, 226 Cartilaginous, 226 Osseous, 226 Dermoid, 227 Corneous, 227 Fatty, 228 Mu- cous, 228 Serous, 228 Glandular, 228 Parenchymatous, 229 Muscular, 229 Nervous, 230. 18* 210 CONTENTS. CHAPTER IV. ORGANIC FUNCTIONS. PAGE Comparison of Animals and Plants 231 > PART II. SPECIAL OR FUNCTIONAL PHYSIOLOGY. CHAPTER I. ALIMENTATION. Mastication and Insalivation 233 Deglutition 233 Gastric Digestion . . . . " . . ' . . . .234 Intestinal Digestion 236 Absorption '. . . 236 Assimilation 238 Nutrition 239 CHAPTER II. CIRCULATION. Action of the Heart 240 Arteries 243 Capillaries 245 Veins 246 Route of the Circulation 246 CHAPTER III. RESPIRATION. Movements . 247 Quantity of Air Changed . . . , . . . .248 Changes of the Air Breathed . . . . i . . .249 Changes produced by Respiration in the Blood .' . . 250 Animal Heat 250 CHAPTER IV. EXCRETION. Secretion of Bile 253 Secretion of Urine . . . .256 Excretion by the Bowels . .259 The Skin. 259 CONTENTS. 211 CHAPTER V. REPRODUCTION. PA.GB General Considerations 260 Male Organs of Generation ........ 262 CHAPTER VI. MUSCULAR ACTION. Voluntary Muscles 266 Mixed Muscles 267 CHAPTER VII. FUNCTIONS OF THE NERYOUS SYSTEM. GENERAL CONSIDERATIONS 267 REFLEX ACTION . . . . . . . . . . 270 GANGLIONIC NERVOUS APPARATUS ........ 272 SPINAL MARROW . 273 ENCEPHALON OR BRAIN . . . . . . . . . 275 Medulla Oblongata 276 Cerebellum 277 Sensorial Ganglia 278 Cephalic Nerves 279 Cerebral Hemispheres 282 SLEEP 284 ORGANS OF SENSATION 285 Touch . 285 Taste . . . . .',.. . . . . .286 Smell . /; 287 Hearing 288 Vision . 291 CHAPTER VIII. THE VOICE. CHAPTER IX. DEVELOPMENT. CONCEPTION 301 THE EMBRYO 301 Amnion 301 212 CONTENTS. PAGE Allantois 304 Decidua 304 Chorion 305 Placenta 306 Umbilical Cord 307 F a. Neck of a gastric tubule, b. Fundus. c. Orifices of tubules, m. Muscular coat. diastase of plants, already alluded to. Being complex, it is prone to chemical change ; and, by contact, institutes the same kind of chemical movement among the particles of food with which it is mixed. The gastric juice is believed to digest especially nitro- genous food ; as the lean of meat, the gluten of bread, and the casein of milk. The products of this digestion have been, by Leh- mann, called peptones; that of albuminoid food, albuminose. 1 A patient of Dr. Beaumont of Ohio, whose stomach was wounded by the bursting of a gun, leaving a permanent opening or fistula. 236 PHYSIOLOGY. Gastric juice is not present in any quantity in the stomach when it is empty ; but begins to be secreted by its glands as soon as food is taken. The amounts of the digestive fluids secreted in a man in 24 hours are thus stated by Dr. Dalton : Saliva . . . . . . 2.880 pounds. Gastric juice . . . . . 14.000 " Bile 2.420 " Pancreatic juice .... 1.872 " 21.172 " The result of gastric digestion is called chyme. Besides the action of the gastric juice upon nitrogenous matters, no doubt some easily soluble substances are ready for ab- sorption as soon as they enter the stomach. This is probably the case with sugar and dilute alcohol. Strong alcohol, as raw spirits, irritates the stomach, and interferes with secretion and absorption. Many dissolved medicines also are absorbed at once, into the capillary bloodvessels of the stomach. The pylorus \s a, muscular valve constricting the left end of the stomach, so as to prevent the passage of undigested food. When reduced to chyme, it is allowed to pass into the duodenum. Intestinal Digestion. Bile and pancreatic secretion are poured into the duodenum by the ducts of the liver (and gall bladder) and pancreas. It is a common opinion that both continue and complete the digestion of food ; especial \y fatty food. In two modes is this believed to take place. One by the alkaline material (soda, potassa) of the two secretions saponifying the fat, that is, making a soap by combining with the fatty acid, oleic, margaric, or stearic, etc. Soap is soluble in water, and thus absorbable ; as fat or oil is not. Also, an emuhijication or suspension takes place, like that made by mixing oil first with gum Arabic and then with water; so that in the state of minute sub- division, almost identical with solution, the oil may be absorbed. Dr. Dalton, however, does not admit that the bile takes part in digestion, although acknowledging that very little of it is excreted from the bowels, and that the larger amount of it not passing out must have some important function to perform before its re-ab- sorption from the intestinal canal. Absorption. The pancreatic juice, containing the organic agent pancreatin, is considered by Dr. Dalton and others to emulsify fatty materials of food. By this process, and the continued action of the gastric FOLLICLES OF PIG'S STOMACH. ABSORPTION. 231 Fig. 117. juice derived from the stomach, chyle is formed. This is absorbed by the villi or minute velvety tufts, of the terminations of the lacteal vessels. Each villus contains the loop-like beginning of a lacteal tube; and each is covered by a layer of epi- thelial cells. It is uncertain whether these cells fill by absorption and then burst into the interior of the villus, or whether they simply transmit the chyle ; probably the latter. Lacteals receive their name from the milky appearance of chyle, which is especially marked after a meal. All of these vessels pass through mesenteric glands to empty into the thoracic duct. Besides lacteal absorp- tion, the bloodvessels of the small intes- tine, like those of the stomach, absorb the products of digestion. The veins of the upper portion of the alimentary canal empty into the portal vein. This VILM OF INTESTINE. Fig. 118. PIECE OF ILKCM. 238 PHYSIOLOGY. goes to the liver, subdividing into capillaries as it enters that organ. Probably the secretion of the glands of the small intes- tine (succus entericus) may have some digestive action ; but it has not yet been demonstrated. Undigested food is, as refuse, con- veyed, by the peristaltic action of the intestinal tube, through the ileo-colic valve to the large intestine, to be excreted as a part of the feces. Assimilation. With good reason, this is ascribed as a principal function to the liver ; through which so much blood, enriched, after eating, by the materials digested and absorbed, passes, entering by the portal vein. Exactly what is done in this process we cannot explain. After death, Bernard and others have found a saccharine substance, glucose, liver-sugar. Pavy asserts this to be a post-mortem educt. A sugar-producing substance, at least, glycogen (hepatin, liver- dextrin), must be admitted to be formed naturally in the liver. Its after destination is doubtful, except that, by the hepatic vein, it goes on toward the general circulation. Some believe that it acts as a "fuel for combustion," for animal heat, being "burned off " in the lungs. Dr. McDonnel has proposed the view that, in assimilation of blood brought by the portal vein, glycogen com- bines with nitrogenous materials of the food, to make plastic mate- rial for tissue. Besides the liver, the mesenteric glands are almost certainly assimilating organs. Chyle is obviously altered by its passage through them. In foetal and infantile life the thymus and thyroid glands probably have the same use. The lymphatic glands are supposed to restore to the Fig. 119. lymph reabsorbed by the lymphatics (as the sur- plus of nutrition) all over the body, some qualities necessary for its farther utility. Gray ascribes to the spleen the office of regulating the quality of the blood, by producing new blood corpuscles when they are deficient, and destroying a portion of them when they are excessive. It may be re- marked that this theory is not certainly establish- ed. More probable is the opinion that the spleen is a diverticulum or reservoir of blood, re- ceiving it especially from the stomach when that organ is function- THYMUS. NUTRITION. 239 ally inactive. A case has been reported (Med. Times and Gazette, Dec. 7, 1867) in which the spleen was removed entirely ; yet the woman recovered and seemed to have good health. Nutrition. This term may, of course, be attached to all that concerns the alimentation of the body. Physiologically, however, it is applied Fig. 120. THE LYMPHATICS. a. Receptaculum chyli, commencing thoracic duct. c. Descent of the latter to its termination, v. Innominate vein. 240 PHYSIOLOGY. more especially to the direct appropriation of plasma of the blood to the building up of the tissues. Nutrition, in this sense, com- prises four processes : formation, development, growth, and repair. The first two of these are predominant in embryonic life. Growth, as well as development, goes on from conception in utero to matu- rity. After that, repair is the only result of nutrition ; repair of tissue destroyed in active or passive waste, or by disease or injury. Construction and destruction are going on together throughout life. In the formation and repair of organs, the selective power of cells, or their nuclei, is manifest. Harmony of action is also ob- served in the construction of contiguous or related parts, as though there were a purposive combination among them. Thus, the eye and its orbit, the brain and the skull, are proportioned to each other. Most wonderful is the exact symmetry of the two sides of the body and of most of the organs. When this is interfered with, during gestation and development, deformity results ; as spina bifida from imperfect union of the two halves of the spinal column, or hare-lip from a similar want of closure near the middle of the face. The conditions necessary to the healthy nutrition of any part of the body are, 1, a sufficient supply of blood ; 2, good quality of the blood ; 3, supply of nerve-force ; 4, functional exercise ; 5, due intervals of repose. CHAPTER II. CIRCULATION. THE distribution of the blood throughout the body is effected by the heart, arteries, capillaries, arid veins ; a continuous closed system, with no outlet, except by transudation through the walls of the capillaries. Action of the Heart. The heart in man is double, as though two hearts were placed side by side. In fo3tal life they communicate directly ; but after birth indirectly only. One-half of the heart, the right, receives venous blood from the body and propels it to the lungs ; the other, the left, receives arterial blood from the lungs, and, through the aorta and its branches, sends it all over the body. The right half might, therefore, be called the respiratory heart, and the left the systemic. ACTION OF THE HEART. 241 Fig. 121. Cavities. Each of these halves of the heart has two cavities ; an auricle and a ventricle. The first is a receiving, and the last a propelling cavity. The right auricle receives venous blood from the venae cava3, and pushes it on into the right ventricle. This then propels it, through the pulmonary artery, to the lungs. The left auricle receives blood from the lungs, and transfers it to the left ventricle, which then propels it out by the aorta. The size of the heart is about that of the closed fist. Anatomists state that it continues to grow later in life than any other organ. Each of the ventri- cles will hold about three ounces; each of the auricles, rather less. The walls of the ventricles are much thicker than those of the auricles; those of the left being thickest. The force of contraction of the left ventricle is estimated by Valentin at ^ of the weight of the whole body ; of the right, half as much. The latter has to send blood only through the lungs ; the former, through the whole body. The tissue of the heart (inclosed in the pericardia! sac) is muscular ; of red muscular fibres, spirally arranged ; a sort of double or returning spiral. When it contracts, that is, during the systole or contraction of the ventricles, the heart elongates (as shown by Dr. Pennock, of Philadelphia), and is twisted forwards so as to strike the left side below the nipple. This constitutes the impulse. The dilatation of the cavities of the heart appears to result from elasticity only ; it has almost no appreciable suction power. Valves. Between each auricle and the corresponding ventricle there is a membranous and muscular valve; the tricuspid valve for the right side, the mitral for the left. (See Anatomy.} After the auricle contracts, the contraction of the ventricle follows ; and, with this, the muscular columns of the auriculo-ventricular valve close it against the return of the blood. When the ventricles have contracted, the rebound of the arteries pushes out the pocket- like semilunar valves of the aorta and pulmonary artery, so as to close them together. The cause of the heart's action is, probably, the contractility of its muscular tissue, under the stimulation of oxygenated blood. Brown-Sequard's theory of its being due to the action of carbonic acid in the blood is untenable. Rhythmic (i. e., regularly alter- nating or successive) contraction is the general, indeed the uni- versal law of healthy muscular tissue ; as has been proved lately by M. Marey's experiments, even when it seems to be continuous. 21 DIAGRAM OF THE CIRCULA- TION. 242 PHYSIOLOGY. The form of the heart and the arrangement of its fibres, are such as to give a magnitude to its alternation of action and repose, such as is only seen in the body elsewhere in the muscular movements of respiration. Although minute ganglia are discoverable in the Fig. 122. SEMILIJNAR VALVES. tissue of the heart, and branches of the pnenmogastric nerve go to it, so that it is under the influence of the nervous system, and is often much affected by its condition (as in emotion), yet this influence seems to be modifying rather than essential. Sounds. Placing the ear over the heart, we hear two sounds lub-dup the first longest and loudest. If we divide the whole time of the two sounds and the following pause into four equal parts, the first sound, and the interval between it and the second, will occupy two of these, or half of the whole time of the rhythm ; the second sound, nearly one part or one-fourth of the whole; and the pause a little more than one-fourth. The first sound occurs with the systole or contraction of the ventricles ; the second, with their diastole or dilatation. The causes of the first sound are, 1, the closing, with vibration, of the auriculo-ventricular valves ; 2, the impulse against the wall of the chest; 3, the rush of blood into the vessels; 4, the friction of the muscular fibres of the heart against each other. The cause of the second sound is, the flapping together of the semilunar valves of the aorta and pulmonary artery, with the arterial rebound during the diastole of the ventricles. During the first sound, the ventricles are contracting, and the auriculo-ventricular valves are closed ; the semilunar arterial valves are open. During tle second sound, the ventricles are dilating, the auricles contracting, the mitral and tricuspid valves are open, and the semilunar valves of the arteries closed. The heart contracts, in an adult, from 70 to 75 times in a minute, while in health and at rest. Its average rate is : THE ARTERIES. 243 At birth, times in a minute . First year " " " Second year, times in a minute Third year " Seventh year " Fourteenth year Middle life Old age 140 to 120 120 115 100 90 85 75 70 115 100 90 85 80 70 50 In very advanced age, however, sometimes it quickens greatly. Dr. Guy found that the pulse was most rapid in the standing Fig. 123. VEINS OF THE BASE OF THE HEART. a, 1. Right auricle. 2. Trieuspid valve. 3. Right ventricle. 4. Pulmonary artery. 5. Left auricle. 6. Mitral valve. 7. Left ventricle. 8. Aorta. 6 shows the mitral and bicuspid valves open, and the arterial valves closed, c shows the opposite ; as during the systole of the ventricles. posture ; next sitting, slower lying down. This depends on the muscular effort made in supporting the body. In the female it is, a little more rapid than in the male of the same age. In disease it is much more often accelerated than retarded. Great debility is nearly always accompanied by acceleration as well as feebleness of the pulse at the wrist, and of the impulse of the heart. Guy found the pulse somewhat more rapid in the morning than in the evening during health. In disease, it is commonly most rapid in the evening. Ordinarily, there is a nearly constant relation between the pulse and the frequency of the respiratory movements ; there being one pulsation of the heart to three or four respirations. The Arteries. All arteries, except the largest, having (un striped) muscular tissue in their middle coat the smallest arteries the most this 244 PHYSIOLOGY. must have some influence upon the flow of the blood through them after the reception of it from the heart. The arteries are found empty after death ; as, in their last contraction, they force the blood into the less resistant veins. The common view among physiologists at the present time is, that the sole office of the muscularity of the arteries is, to limit, by resistance, the amount of blood passing through them. That is, as Virchow has expressed it, the more healthy and vigorous the action of an artery, the less blood goes through it. This opinion is founded upon some experiments of the Webers ; who found that the intestinal canal, heart, and arteries, when powerfully acted upon by galvanism, v/ere thrown into a state of rigid or tonic con- traction. They thence concluded, that, though the intestinal tube has peristaltic contraction, and the heart an alternating impulse, the arteries have normally only a power to become rigid with a certain force when blood is forced into them. 1 The elasticity of the arteries must have much to do with the change of the flow of blood, gradually, from an intermittent to a steady stream, such as we find passing from the capillaries to the veins, and through the latter to the heart. If we admitted an active propulsive power in the arteries, supplementary (as Sir Charles Bell held) to that of the heart, the pulse at the wrist, or elsewhere, would be explained by these forces combined. On the current view, however, the pulsation of arteries is due entirely to the impelling action of the heart, driving the blood through them. At the same time, it is well understood that the regulation of the varying supply of blood to different parts must depend mainly upon the condition of the arteries ; as the heart acts impartially towards all, having one trunk only, the aorta, to give out its supplies. In the growth of the deer's horn in the spring, the rutting or periodical geni- tal excitement of many animals, the development of the uterus during gestation, and of the mammary gland before and during lactation, there is an unusual flow of blood through those organs. Under other circumstances, as in Bernard's experiment of dividing the sympathetic nerve in the neck, arteries are dilated passively, by paralysis of the muscular coat. The flushing of the skin upon a blow or friction, or under the stimulation of mustard, ammonia, etc., seems to show a reflex 'action of the bloodvessels, under nervous influence. On the fact that the vaso-motor nerves, i. e., those which go to the bloodvessels, are all derived from the ganglia of the sympa- thetic system, certain speculations concerning the action of cold 1 See Transactions of the American Medical Association, 1856, for an argument by the present writer (Prize Essay on the Arterial Circulation) in opposition to this view, and advocating the existence of an actirely propelling power in the arteries. Also, American Journal of Medical Sci- ences, July, 18G8, p. 288. THE CAPILLARIES. 245 and heat upon the circulation, through the ganglia, are founded ; making the basis of the "ice-bag" and "hot-water-bag" practice of Dr. John Chapman. Neither the practice nor the theory is as yet established ; nor does the one necessarily depend upon the other. The Capillaries. Having but a single coat, without muscularity, these interme- diate vessels can have no office but to subdivide, in fine networks, Fig. 124. CAPILLARIES. a. Capillaries of the papillae of the skin of a finger, b. Capillaries of villi of small iutestiues. the blood ; so that it may afford nutriment, by transudation of the plasma through their walls; or, in the glands, allow secretion ; or, in the lungs, expose the blood to the air. Capillaries contract only by elasticity; so as, after being dilated, to return, on the withdrawal of pres- sure, to their ordinary dimensions. Yet, two powers have been pointed out as, in the capillary region, con- tributing to the movement of the blood. One of these, as shown by Dr. Draper, is common to plants, animals, and some materials of an inorganic nature; viz., capillary ac- tion ; that is, the attraction of the walls of fine tubes for liquid in which they are immersed, varying with the smallness of the tube and the nature of the materials used. The other agency, first pointed out by Dr. Draper, is also present both in animals and plants. It is 21* Fig. 125. CAPILLARIKS OF A Toom 246 PHYSIOLOGY. the attraction which the tissues of the organism have for the nutri- tive materials circulating in its vessels. This " vital or nutritive affinity" is a vis d fronte ; which, as it constantly takes, in nutri- tion, particles from the blood in the capillaries, must diminish pres- sure in resistance, and favor the onward flow. The Veins. Valves along the course of nearly all the veins, opening only towards the heart, economize the power used in returning the blood through them (from the capillaries) to the heart. The pressure of the muscles during exercise contributes to the same end. So does inspiration tend to promote the return of the blood through the vena3 cavse to the heart ; since the lifting of the ribs lessens the pressure upon the heart's surface, or, in other words, exerts some "suction" power upon it. The larger veins have an appreciable amount of muscular tissue ; the smaller ones, none. It is natural to suppose that this is because the largest, being nearest the end of the round of circulation at the heart, require the most power to complete the circuit. The velocity of the blood-movement is greater in the arteries than in the veins. The capacity of the venous system is about three times as great as that of the arterial system ; and the angles at which branches join the veins are much larger than those at which branches leave the arterial trunks. These facts account for the greater slowness of the venous current. By experiments with chemical reagents introduced into the veins, it has been shown that the blood passes round its course in less than half a minute, in some instances, and in others in about a minute. It is not equally rapid at all times, nor even through all the different organs of the same body. Route of the Circulation. Although perhaps not necessary in this place, we may recapitu- late the round of the circulation, as follows : Beginning at the aorta, the blood is distributed by its branches to all parts of the body. The small arteries terminating finally in capillaries, these, in various networks, subdivide the blood for the supply of the different organs. Then the capillaries unite to form veins, and these, larger ones, till finally all combine to end in the ascending and descending vence cavce. These empty into the right auricle. This pours its blood through the tricuspid valve into the right ventricle ; which, by the pulmonary artery and its branches, sends |t to the lungs. Thence, by the four pulmonary veins, the blood is brought to the left auricle. Through the mitral valve, it is passed on into the left ventricle ; whence it again is thrown into the aorta. The portal circulation of the liver is, as has been already explained, a deviation from this simple course of the general sys- tem ; since the porta! vein, instead of going to empty jts contents RESPIRATION. 247 directly into the venee cavae, breaks up into capillaries to enter the liver; whose blood is then collected by the hepatic vein, by which it is conveyed to the vena cava. The discovery of the course of the circulation was made by Dr. William Harvey, about It: 19. CHAPTER III. RESPIRATION. THIS function has for its purpose the aeration of the blood. It is accomplished by the exposure of the venous blood, brought from the right half of the heart, to the air received into the air-vesicles of the lungs. The immense number of these vesicles (about six hundred millions), provides a very large expansion of surface. Air Fig. 126. and blood both periodically enter and pass through the lungs ; al- though the blood is entirely con- fined within the capillaries. The heart sends a new supply of venous blood with every systole ; the lungs receive a fresh quantity of air with each inhalation. Movements of Respiration. These are, inspiration and expi- ration. The first is accomplished by expanding the chest, so as to take pressure from the outside of the lungs, while the mouth or nostrils are open to allow the en- trance of air. It is precisely the action of filling a pair of bellows with air by drawing apart the handles. This expansion of the chest is effected in two ways: 1, elevation of the ribs by the in- tercostal muscles ; 2, depression of the diaphragm by its own con- traction. The intercostal muscles, internal and external, have their fibres crossing in opposite directions. This obliquity adds to the extent of their action in lifting the ribs; as every muscle shortens, in its DIAGRAM op AIR-CELLS 1. Small bronchial tube 2. Vesicular portion of lobule. 3. The same, laid open. 248 PHYSIOLOGY. contraction, about one-third of its length, therefore the longer it is, the greater the distance through which it draws what it moves. Breathing chiefly by action of the intercostal muscles in lifting the ribs is called costal respiration ; by the diaphragm mainly, abdomi- nal respiration. The latter is observed in young children ; the costal type, in women. Abdominal respiration is so called, be- cause, when the diaphragm descends, it forces out the organs of the abdomen perceptibly. In violent efforts of inspiration, as in asthma or croup, accessory muscles of respiration assist the intercostals and diaphragm. The principal of these are the levatores costarum. But other muscles may contribute aid even those of the neck; and sometimes the nostrils are forcibly dilated in the struggle for air. Ordinary expiration follows the cessation of the muscular act of inspiration, not requiring any positive effort of muscular con- traction. The weight of the ribs causes them to fall ; the elasti- city of the diaphragm makes it ascend ; the same property in the lungs induces their contraction and the expulsion of the air. The elasticity of the costal cartilages also assists. Forced expiration, however, as in blowing hard, involves (besides the accessory action of the ster no -co stalis muscle) compression upward of the dia- phragm, by the superficial muscles of the abdomen (external and internal oblique, trausversalis, and rectus) pressing in the contents of the cavity under them. Quantity of Air Changed. With each breath, a man changes about twenty-five cubic inches of air. By forced expiration, one can expel a much larger amount. Still a quantity will remain in the lungs, which cannot be driven out. This residual air varies probably from forty to two hundred and sixty cubic inches. After a deep inspiration, a healthy man, five feet seven inches in height, can, on the average, expel from his lungs two hundred and twenty-five cubic inches of air. This was called, by Mr. Hutch- inson, the vital capacity. For every inch above the height just named, the capacity of the chest increases about eight cubic inches; and for every inch below, it is diminished in the same proportion. Less regular correspondence exists in regard to weight. Mostly it does not vary much with weight under one hundred and sixty- one pounds. Over that, each additional pound of weight brings a cubic inch of diminution in vital capacity, so called. With age, this increases from fifteen to thirty-five years, at the rate of five cubic inches per year. Then it diminishes, one and a half cubic inches each year, to sixty-five years. Bourgery states that women have but half the breathing capacity of men of the same age. The number of respirations usual in an adult in health is from fourteen to eighteen in a minute. The force of ordinary CHANGES OF THE AIR BREATHED. 249 inspiration is calculated to be equal to a weight of two hundred pounds lifted. Changes of the Air Breathed. Common air consists of about seventy-nine volumes of nitrogen, and twenty-one of oxygen ; with about four parts in ten thousand of carbonic acid, a variable amount of watery vapor, and some non-essential gases and particles. After passing through the lungs, a portion of air has become warmer ; its oxygen is diminished, its carbonic acid and watery vapor increased. The increase of carbonic acid may be shown by the milky turbidness produced by breathing into clear lime-water. The vapor of water in the breath is made known in the open air on a cold day, by the cloud condensing near the nostrils or mouth. For every thousand volumes of carbonic acid exhaled, Valentin and Brunner assert that over one thousand one hundred and seventy -four volumes of oxygen gas are absorbed into the blood. In an hour, 1583.6 cubic inches of oxygen are absorbed on the average. Pettenkofer has shown that more oxygen is absorbed at night than during the day. Of carbonic acid, about 1345.3 cubic inches are given out every hour, containing one hundred and seventy-three grains of carbon ; or eight ounces of carbon in twenty-fouT hours. The amount of this exhalation varies, however, with age, sex, temperature, and purity of the air. From eight to thirty years of age, in males, the amount of car- bonic acid exhaled increases ; from thirty to forty it is nearly the same ; after that time it diminishes gradually. In females, it is less than in males of the same age ; it increases from eight years till puberty, and then remains stationary throughout the menstrual and child-bearing period of life. The faster one breathes, the less is the proportionate amount of carbonic acid exhaled. As to temperature, between 38 and 7o Fahr., every rise of 10 is attended by a lessening in the carbonic acid given out, of two cubic inches per minute. An atmosphere containing five or six per cent, of carbonic acid gas is not capable of long sustaining life. Ten per cent, may produce immediate danger. While pure carbonic acid is irrespir- able, its dilution causes it to be tolerated by the breathing organs. Hence the peril of life in some deep wells, brewers' vats, and rooms in which charcoal is allowed to burn without ventilation. The use of food increases the amount of carbonic acid in the air expired. Alcoholic drinks diminish it. Exercise increases it. Sleep diminishes it. The amount of watery vapor exhaled from the lungs is, on the average, a pint in twenty-four hours. 250 PHYSIOLOGY. Changes Produced by Respiration in the Blood. The color of the blood is altered in the lungs, from dark crimson or purple to bright scarlet. The blood is also 1 or 2 warmer; 1 it contains more oxygen, less carbonic acid, and more fibrin. The introduction of oxygen gas, and the elimination of carbonic acid gas, are, as already observed, the two great purposes of respira- tion. Yenous blood is that which has been, by various influences during its flow, rendered unfit for the support of vital energy. Arterial blood has been revivified by its purification and oxygena- tion. When these changes are prevented, as in strangulation, drown- ing, or asphyxia by irrespirable gases, the dark blood is unable to maintain the vitality of the nerve-centres ; and the blood ceases even to flow through the vessels. Drowning occurs, therefore, not from any directly injurious effect of the water in the lungs, but from the simple exclusion of air. So in some of the deaths from inhalation of chloroform, the cause probably has been the deficient admixture of air with the anesthetic. That substance is, however, capable of causing fatal arrest of respiration, appa- rently by its toxic influence upon the medulla oblonyata, the nerve- centre of respiration. Recovery from drowning seldom occurs when the individual has been submerged as long as five minutes. Rare instances are narrated, in which it has been fifteen minutes. Even practised pearl-divers can seldom stay under water for one whole minute at a time. Animal Heat. In the armpit, or under the tongue, the temperature of the adult human body is, in health, 98.4 or 98.5 Fahr. The heat of the blood is 100 to 103. Children have a temperature two or three degrees higher. In disease, especially in scarlet fever and yellow fever, it has been known to reach 108, and, it is said, 112. Cholera, pernicious fever and cyanosis are attended by depression of temperature. In cholera, it has gone down during life to 77. Other parts of the body are cooler than the armpit ; the sole of the foot does not average in health above 90. During sleep, the heat of the body goes down about 1J degrees. It is highest early in the morning, fluctuates through the day, and is lowest about midnight. Exercise elevates it considerably ; eating does so to a less extent. The reaction following a cold bath may raise it one degree or more. As we are constantly giving off heat by radiation, conduction, and evaporation to surrounding bodies, it must be supplied by processes going on within the system. The explanation long held 1 This is not admitted by all observers. ANIMAL HEAT. 251 by physiologists to be most probable is, that our animal heat is produced by slow combustion; that is, the union of oxygen with the carbon, hydrogen, nitrogen, sulphur and other elements of the blood and tissues, giving out heat less rapidly, but in the same quantity, as when wood, coal, oil or other fuel is burned in the air. Liebig has asserted, on calculation, that the amount of carbon and hydrogen shown to unite with oxygen in the body is sufficient to account for all its animal heat. Warm-blooded ani- mals always breathe a great deal of air (birds, for example), and consume a great deal of carbonaceous food. Whether materials of food are ever "burned off" from the blood in the generation of heat, without entering first into the tissues, is not certain ; pro- bably it is so. In cold climates, Arctic explorers have found the demand for fatty (carbohydrogenous) food to be very much greater than in warm or temperate regions. It must be understood, however, that the "combustion" of materials in the body is not, like that of wood or coal, a simple process of direct conversion of carbon, by oxidation, into carbonic acid, and of hydrogen into water. Step by step combinations are formed, of which the last results, only, are these familiar substances. Prof. Dal ton regards animal heat as the result of a chemical, but not strictly of a combustive process. His language is, in part, as follows: 1 "The numerous combinations and decompositions which follow each other incessantly during the nutritive process, result in the production of an internal or vital heat, which is pre- sent in both animals and vegetables, and which varies in amount in different species, in the same individual at different times, and even in different parts and organs of the same body." The nervous system has a considerable though unexplained in- fluence over animal heat. This is shown by the coldness following great shocks to the nervous centres, the loss of temperature in paralyzed limbs, and the occasional increase of temperature under nervous excitement. The power of resisting the depressing action of exposure to cold is greatest in adolescence ; least in infancy and old age. Clothing, by its non-conducting property, retains heat, that is, prevents or retards its loss ; but it does not make us warm, in a positive sense. 1 Treatise on Physiology, 4th edition, p. 247. 252 PHYSIOLOGY. CHAPTER IV. EXCRETION. BESIDES carbonic acid, which must be thrown out from the blood, other substances, results of chemical changes in the different parts of the living body, have to be removed from it. No particle seems to remain permanently in the form and condition into which it is organized ; but each passes from the organic to the effete or post-organic state ; when, if retained, it will be obstructive and injurious to the system. Poisonous and even fatal effects may result from the retention in the blood of excrementitious matter ; as, in uraemia, when the action of the kidneys is suppressed; cho- Icemia, when the liver fails to secrete bile, etc. Toxaemia is blood- poisoning from any cause. This is prevented very often, even when deleterious agents have been taken into the blood, by the emunctories or excretory organs eliminating it. Excretion is always a secretory process; but secretion is not always excretion. The former term is applicable whenever any- thing is, by glandular or follicular action (i. e., by the selective power of cells), separated Fi S- 127 ' from the blood. The lat- ter, excretion, occurs only when the material removed is altogether waste, and cannot be used for any pur- pose connected with the or- ganism. Milk, for instance, is a secretion, but not an excretion ; because it is available, and is produced, for the nourishment of off- spring. Urine and feces are entirely excretory. Bile is only partly so. Secretion and excretion being, however, so nearly BRUNNER s GLAND. MAGNIFIED. ... . alike in nature, we may, without impropriety, enumerate together their most definite pro- ducts, as follows : SECRETION OF BILE. 253 Ptyalin, Cholesterin, Pepsin, Taurocholic Acid, Pancreatin, Glycocholic Auid, Creatin, Glycogen, Creatinin, Excretin, Lactic Acid, Stercorin, Lactin, Urea, Butyrin, Uric Acid. Pigments, as biliary coloring matter (biliverdin, biliphein, or cholepyrrhin) and coloring matter of the urine (urosacin, uroxan- thin). Also, excretory salts; as urates, phosphates, sulphates, &c., dissolved in water. The most important excrementitious substances of the body are thus stated by Dal ton : 1. Carbonic Acid C0 2 . 2. Urea C 2 H 4 N 2 2 . 3. Creatin C 8 H 8 N 3 O 4 . 4. Creatinin C 8 H 7 N 3 O a . 5. Urate of Soda NaO,C 5 HN 2 2 +HO. 6. Urate of Potassa KO,C 5 HN 2 O 2 . 7. Urate of Ammonia .... NH 4 0,2C 6 HN 2 O 2 4-HO. The organs which are altogether excretory, in the human economy, are, the kidneys and the large intestine. Partly so, are the lungs, liver, and skin. Having considered already the func- tional action of the lungs, we may now briefly attend to that of the liver, kidneys, bowels, and skin. Secretion of Bile. Only the liver, of all the glands of the human body, is supplied with venous as well as arterial blood. Although the main purpose of this is, probably, the assimila- tion of crude blood coming from Fig- 128. the digestive organs, it is not possible to say whether the bile is mainly produced from the blood of the hepatic artery or from that of the portal vein. That vein is supplied by branches from the stomach, spleen, pancreas, and small in- testine. Entering the liver by two main branches, the portal LOBULE OF LIVER. vein subdivides and ramifies into the interlobular veins. These, as well as the minute branches of the hepatic artery, make the capillary networks, which surround the acini or lobules of the liver. From the centre of each of these lob- ules or "islets," goes off a ramule (intra-lobular vein) contributing 22 254 PHYSIOLOGY. to the hepatic vein. From the same acini also pass off the tubules which carry bile, and which by combining make finally the biliary or hepatic duct. Among the capillary meshes of the acini, and inclosed within each, so as to be in direct contact with the biliary tubules, lie the secreting hepatic cells. These take from the blood materials from which they elaborate the bile. Leaving the liver, the bile commonly goes backward through the gall-duct to the gall-bladder, where it is held in reserve, to be LOBULE OP LIVER. forced out, by the ductus communis choledochus, into the duodenum, from time to time. Human bile is yellowish-brown in color, and of a peculiar acrid or bitter taste. Its reaction to test paper is disguised by its bleaching litmus; but it is probably neutral when fresh, tending to alkalinity on keeping. It makes a lather-like foam when shaken in a tube. Nearly two and a half pounds of bile are estimated to be secreted by an adult in twenty-four hours. Characteristic ingredients of bile are, biliverdin (coloring prin- ciple), cholesterin, glyco-cholate and tauro-cholate of soda ; also, chloride of sodium, oleate, raargarate, and stearate of soda and potassa, carbonate and phosphate of soda and potassa, and phos- phates of lime and magnesia. Biliverdin does not pre-exist in the blood. It must be formed in the liver. After its formation, it may be re-absorbed, when, for instance, the gall-duct is obstructed by gall-stones, and then it may be thrown out from the blood into the skin (jaundice) and tissues and secretions generally. It is a nitrogenous substance. Cholesterin is a fat-like non-nitrogenous crystallizable substance, distinguished from the fats by not making soap with alkalies. It is not formed in the liver, but reaches it in the blood, being derived apparently from the waste of tissue in the brain and other parts of the nervous system, and from the spleen. Cholesterin is, accord- ing to the investigations of Prof. A. Flint, Jr., changed into other SECRETION OP BILE. 255 substances (stercorin, excretin) in the intestinal canal ; not being found in the feces. Bilin or biliary resin consists chiefly of glyco-cholate and tauro- cholate of soda. The former of these crystallizes readily ; the latter with difficulty, if at all. They are distinguished also by the fact that the first is precipitated by acetate of lead, while the other is not. Both are nitrogenous ; but tauro-cholic acid is peculiar in containing sulphur. These substances are formed in the liver. Pettenkofer's test for bile is believed to be the best. It consists in mixing with the liquid to be examined a little cane sugar, and then adding sulphuric acid, drop by drop. A red color appears, changing gradually to lake, and finally opaque purple. Biliary coloring matter, but not the resinous salts of the bile, is tested by nitric acid ; which produces a green color with it. Fig. 130. SECTION OF LIVER OF THE HORSE. Uses of the Bile. Most physiologists ascribe to the bile a share with the pancreatic secretion in the digestion of the fat of our food. It is usually secreted in largest amount not long after a meal. Nearly all of the biliary substances proper are reabsorbed from the intestine. Experiment shows that it is necessary to health and even to the life of an animal, not only that the bile should be secreted and discharged, but that it should be passed into the alimentary canal. All these facts combine to prove that it partakes in the completion of the digestive process. Against this, Dr. Dalton urges that experiments with bile out of the body 256 PHYSIOLOGY. have not succeeded in showing that it has any positive reaction with either albumen, starch, or fat, at a temperature of 100. BILE-DUCT AND CELLS. Probably the bile also acts as the natural "peristaltic per- suader," or stimulant of muscular contraction in the intestine. By its proneness to alkalinity, it may neutralize excess of acidity in the bowels ; and, by its antiseptic quality, retard putrefactive changes in the refuse of blood. Secretion of Urine. There is no doubt that it is in the cortical portion of the kid- ney that urine is secreted. There are the cells of the organ, in close relation to the beginnings of the uriniferous tubules, which then collect, in conical bundles, to end at the pelvis of the kidney. Capillary bloodvessels surround these cells ; each minute tubule also begins in a capsule, which embraces a Malpighian corpuscle, or tuft of capillaries. Very possibly there may be an actual ex- pression or filtration of a portion of the water and salts of the blood, from the Malpighian tufts, into the tubules, through the inclosing capsule. Besides this, however, there is a true secretion, or selective separation, of matters from the blood, by the cortical renal cells. Urine is entirely excrementitious ; serving, after it leaves the kidney, no functional purpose. Its ingredients are all taken from the blood ; not manufactured, although perhaps somewhat modi- SECRETION OP URINE. 257 Fig. 132. fied, in the kidney. 1 The average daily amount in an adult is from thirty-two to thirty-five fluidounces. Its normal specific gravity (water being 1000) is 1024. Its quan- tity and character, however, both vary, even in health ; and, greatly, in disease. Diabetes mellitus is marked by saccha- rine urine, which is very heavy ; up to 1060 or 1070. Hysterical patients often have very abundant urine, pellucid and light; 1006 or 1005. Albuminuria is the presence of albumen in the urine. This occurs transiently in a number of diseases ; permanently, in Bright's dis- ease of the kidney. Diurnal variations take place in the urine in health. Dalton found that passed on rising in the morning to be dense, highly colored, and of acid reac- tion. During the forenoon, pale, light in weight, and neutral or slightly alka- line. In the afternoon and evening it becomes again dense, dark colored, and strongly acid. The following are the constituents of the urine : SECTION OF KIDNEY. Water Urea Creatin ..... Creatiuin ..... Urate of soda \ " " potassa L " " ammonia J Coloring matter and mucus Biphosphate of soda ") Phosphate of soda " potassa \ " magnesia | " lime J Chlorides of sodium and potassium Sulphates of soda and potassa . 938 30 1.25 1.50 1.80 .30 12.45 7.80 6.90 100.00 Urea is a soluble, crystallizable, neutral, nitrogenous substance ; of which the daily average passed by an adult in the urine is from 400 to 600 grains. It is increased by exercise and by highly animalized food. Out of the body, decomposition converts it into carbonate of ammonia. Creatin is a crystallizable, neutral, nitrogenous substance, origi- 1 Zalesky asserts that the kidneys change creatin into urea. 22* 258 PHYSIOLOGY. nating in the muscular tissue as a result of its waste. Being absorbed into the blood, it is thrown out in the urine. Creatinin contains two equivalents less of water than creatin. It is slightly alkaline. Muscular tissue yields it also. Probably creatin is converted into creatinin ; as the latter substance is most abundant in the urine, and the former in the muscles. Fig. 133. STRUCTURE OP KIDNEY. a. Arterial branch. 6. Malpigliian tuft. ef. Efferent vessel. m, m. Capsule, t. Uriniferous tubule. Urates, or salts of uric or lithic acid, are soluble and crystal- lizable salts, containing nitrogen. Urate of soda is the most abundant. They result from the waste or disintegration of the nitrogenous tissues. The rate of metamorphosis of tissue, there- fore, can be approximately estimated by determining the amount of urea, urates, &c., passed. The coloring matter of the urine, urosacin, is usually dissolved in the water of the secretion. Sometimes it is thrown down with other deposits as uric acid or the urates ; making the "lateritious" or brickdust sediment. EXCRETION OF THE BOWELS THE SKIN. 259 Various medicinal and other substances pass from the blood into the kidneys, are thrown out by the urine, and give color, odor, or other properties to it. Excretion by the Bowels. In man, the large intestine has only an excretory function. The feces consist, 1st, of materials of food, not perfectly changed and rendered assimilable by digestion, from their nature or from excess in amount ; 2d, of the secretions of the glands of the large intes- tine, viz., effete matter taken from the blood. The necessity of the regular action of the bowels for health is evident from this double nature of the material passed. Even when no food is taken, as in illness, some discharge, though it may be reduced in quantity, is required. In the feces, excretin, etercorin, ammonio-magnesian phosphate, and other salts, have been found along with remnants of undigested food. The Skin. Two important uses, besides secretion, evidently belong to the skin ; protection of the organs beneath it, and the reception and conveyance of sensation. Two kinds of secreting Fig. 134. glands are found in it ; the sudoriparous or sweat- glands, and the sebaceous glands. The former are most abundant ; on the palm of the hand, for in- stance, 2700 to the square inch. Each sweat-gland is a tubular coil, lined with epithelium, lying just beneath the skin. Its duct penetrates the skin, ending at the cuticle with an oblique valve-like open- ing. Altogether, nearly two pounds of perspiration pass off from the body of an adult in twenty-four hours. Its composition is as follows : Water Animal matters, with lime ....... Sulphates, with substances soluble in water .... Chlorides of sodium and potassium, and spirit-extract Acetic acid, acetates, lactates, with alcohol extract 1000.00 The sebaceous glands abound especially upon parts of the skin covered with hair. Their secretion is unctuous, and maintains the SECTION OF SKIN. 2GO PHYSIOLOGY. suppleness of the skin and hair. In the external meatus of the ear, the ceruminous glands discharge a matter of a peculiar consistence and odor, whose purpose seems to be to exclude insects "from the ear. Insensible perspiration is an exhalation of moisture from the whole surface of the skin. By its evaporation and that of the sweat, the heat of the body is moderated, under exercise, in summer weather or tropical climates. Thus, in a dry air-bath, the tempera- ture of 250 can be readily sustained; in vapor, 150 would be dangerous. Cluibert, the Fire-king, is said to have entered safely an oven heated to 600. CHAPTER Y. REPRODUCTION. General Considerations FOR the indefinite continuance of species of organized beings by the reproduction of individuals, the essential condition is the union of two oppositely polar or " sexual " cells ; the germ-cell and the sperm-cell. In all the higher animals, as in man, these are always the products of different bodies, having concomitant sexual pecu- liarities. Among lower forms, animal and vegetable, true herma- phrodism is sometimes met with ; i. e., the existence of both sexes in the same individual ; as in the tapeworm. Still, even if the uniting cells do not exhibit any palpable differences, the principle of duality seems to be universal in reproduction. Apparent exceptions seem to exist to this law, in several instances. The propagation of plants from cuttings (as the grape- vine), or from "eyes" of tuberous roots (as the potato) is certainly not a dual process. If, then, it be infinite in its possible extent of multiplication, it must be exceptional. But we do not know that it is so. Degeneration of the potato and other plants under that method has been noticed. If this multiplication by division be exhaustible, it is really only the separate growth of dividual parts of the unit of organization from which they came. The tree grows in its cuttings ; and, although their life is prolonged beyond that of the branches which are not planted out, it is still limited ; only seed-life is perpetually renewable. Other seeming exceptions occur in " parthenogenesis," or repro- duction without impregnation, and the "alternation of generations" of certain animals (medusae, salpae, duced by irritating causes in infants and children than in adults. At birth, the twenty first teeth are partly formed in both jaws, but beneath the gums. The following is the usual order of their protrusion or " cutting." Two central incisors, in each jaw, in the seventh month ; two lateral incisors, eighth month ; two an- terior molars (first jaw teeth), end of twelfth month ; two canines ("stomach teeth" of lower jaw, "eye-teeth" of upper), eighteenth month; two second molars or jaw teeth, twentieth to twenty-fourth month. Those of the lower jaw are generally first. At about seven years of age, the second teeth begin to replace the others. The first to appear, commonly, is the first permanent molar tooth, at six years and a half. Next, at seven years, the permanent middle incisors. At eight, the late- ral incisors follow. The first and second bicuspids before ten years of age. The four canines, upper and lower, before twelve. At thirteen, the second permanent molars. The third and last molars (" wisdom teeth") between seventeen and twenty- one ; making in all thirty-two teeth of the second set ; in each jaw, four incisors, two canines, four bicuspids, and six molars. The age of puberty, from fourteen to sixteen in temperate climates, is marked by important changes. Sex is now manifested, by men- struation and the development of the breasts in the female, and by the change of voice and growth of beard in the male. Emotional differences also appear. The muscular system and the bony skeleton develop progres- sively from infancy to maturity. This is seldom reached before the twenty-fifth year. The osseous union of the ends and shafts, epi- physes and diaphyses of the long bones, and that of the different bones of the head, may sometimes be incomplete even to a later period ; and, according to some anatomists, the brain may grow until forty, and the heart still longer. The following table, from Dalton, exhibits the comparative pro- portion of different organs to the whole body, at birth and matu- rity : DEVELOPMENT OF TKETH. 312 PHYSIOLOGY. Foetus at term. Adult. Weight of entire body 1000.00 1000.00 Thymus gland .... 3.00 0.00 Thyroid " 0.60 0.51 Renal capsules .... 1.63 0.13 Kidneys 6.00 4.00 Heart 7.77 4.17 Liver 37.00 29.00 " Brain 148.00 23.00 Old age is shown by general atrophy or failure of nutrition as well as of power ; frequently attended by various forms of degene- ration of structure and defective functional action, tending towards death. RETURN BIOLOGY LIBRARY TQ_L^ 3503 Life Sciences Bldg. LOAN PERIOD I \'2 ALL BOOKS MAY BE RECALLED AFTER 7 DAYS Renewed books ore subject to immediate recall STAMPED BELUVV Subject to Reccl ^mediately UNIVERSITY OF CALIFORNIA, BERKELEY FORM NO. DD4,l 2m , 12/80 BERKELEY, CA 94720 LD 21-100m-7,'40 (6936s) U.C. BERKELEY LIBRARIES CDEb331fi7D UNIVERSITY OF CALIFORNIA LIBRARY