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ALSO, HAVING AN AGENCY IN LONDON, THEY RECEIVE MONTHLY PACKAGES CONTAINING ALL NEW BOOKS AND PERIODICALS, AND IMPORT TO ORDER AT THE LOWEST RATES ENGLISH, FRENCH, AND GERMAN WORKS. THEY ALS(5 RECEIVE SUBSCRIPTIONS FOR ALL AMERICAN OR FOREIGN MEDICAL PERIODICALS. Particular attention will he given to the faithful execution of all orders intrusted to them, which they will guarantee shall be furnished at the very lowest prices. All of the Publications of H. Bailliere, of London and New York, on hand, or furnished at his prices. LINDSAY & BLAKISTON, PUBLISHERS, BOOKSELLERS, AND BOOKBINDERS, No* 25 South Sixth Street, above Chestnut. A TEXT BOOK OP ANATOMY, AND GUIDE IN DISSECTIONS, FOR THE USE OF STUDENTS OF MEDICINE AND DENTAL SURGERY. BY WASHINGTON K. HANDY, M. D. PROFESSOR OP ANATOMY AND PHYSIOLOGY IN THE BALTIMORE COLLEGE OF DENTAL 8TTRG2RY ; LATE PROFESSOR OF ANATOMY AND OPERATIVE SURGERY IN WASHINGTON UNIVERSITY, BA_LTIiIOKK.» WITH TWO HUNDRED AND SIXTY-FOUR ILLUSTRATIONS. PHILADELPHIA: LINDSAY & BLAKISTON 1854. 30794 Entered, according to act of Corgress, in the year 1853, BY LINDSAY AND BLAKISTON, In the Clerk's Office of the District Court for the Eastern District of Pennsylvania. fr«m SHEBWOOD & Co., PEINTERS, BALTIMORE. TO CHAPIN A. HARRIS, M.D. PEOFESSOE OF THE PBINCIPLES OF DENTAL SUEGEEY IN THE BALTIMORE COLLEGE, AS AN ACKNOWLEDGMENT FOR UNTIRING DEVOTION IN THE ADVANCEMENT OF DENTAL SCIENCE, AND AS A TESTIMONIAL OF REGARD FOR GREAT PRIVATE WORTH, THIS WORK IS RESPECTFULLY INSCRIBED, BY HIS GRATEFUL FRIEND, THE AUTHOR. PREFACE. THE author is aware of the many valuable works on Anatomy adapted to the Student and Practitioner of Medi- cine; but he does not know of one that has been arranged with a view also to the claims of the Student and Practi- tioner of Dental Surgery. To prepare a work, therefore, adapted alike for the Dental as well as the Medical Stu- dent— one which directs special attention to the Mouth, showing step by step the important anatomical and physi- ological relations which it has with each and all the organs and functions of the general system — forms one of the leading objects of the present undertaking. Dental Students are slow to see and feel the necessity of a knowledge of any more of Anatomy than so far as the Teeth and their immediate connections in the mouth are concerned, and to go beyond this is thought rather a waste of time, and entirely foreign to the practice of the profes- sion they design to pursue. No work on Anatomy has taken very particular pains to teach them any better. To correct this false and dangerous sentiment, and to demon- strate the necessity of anatomical knowledge to the scien- tific, skillful, and successful Dentist, equally with that of the Physician, forms the second and chief reason which has induced the author to write the present work. The Plan of the work, after giving a general outline of Organization, divides the subject into four parts: The first part teaches the Alphabet of Anatomy, or the Elementary Tissues of the Body, whose varied combina- VI PREFACE. tion constitutes the Anatomical Language, or the various organs composing the General System. The second part begins with the Head, and describes its organs, as far as possible, in their functional order and dependency; thus combining the Anatomy and Physiology of the several organs, however various, concerned in any particular function — a plan found to be most interesting? and, it is believed, at the same time most practical and useful. This part is then made complete by showing the Anatomical and Physiological relations of the Mouth with the different parts of the Head. The third part,, embracing the Trunk, is examined in the same physiological order, and completed in the same manner, by demonstrating the Eelations of the Mouth with its several organs, viscera and functions. The fourth part comprises the Extremities, which do not admit of the same kind of arrangement so readily, and are demonstrated in the ordinary way. The author has freely consulted the best sources of authority, and here desires to make his acknowledgments to the works of Wistar by Pancoast, Homer, Smith's Ana- tomical Atlas, Bell by Godman, Quain, Wilson, Sharpy and Quain by Leidy, Cloquet, Cruveilheir by Pattison, Von Behr's Hand Book of Human Anatomy, The Dublin Dis- sector, Solly on the Human Brain, Knox's Manual of Anatomy, Holden's Manual of Dissections, Morton's Hu- man Anatomy, Nasmyth, Goodsir, Owen, Harris, Tomes, Carpenter's Human Physiology, Carpenter's Principles of General and Comparative Physiology, Muller by Bell, Magendie; and most especially does he return his thanks to Professors Harris and Piggot for their kind assistance and valuable suggestions, while the work was passing through the press. PREFACE. VII The Index, it will be perceived, has been arranged some- what differently from the one in common use, that is to say, instead of finding all the bones arranged under the one head of bones, muscles under the one head of muscles, arteries under the one head of arteries, &c., each bone, muscle, artery, &c., will be found under its proper alpha- betical head. W. K. HANDY. BALTIMORE, OCT. 19, 1853. CONTENTS. INTRODUCTION. PAGB HISTORY OF ANATOMY,.- > 33 GENERAL RULES FOR CONDUCTING DISSECTIONS, 40 ORGANIZATION, 41 ANALYSIS OF ORGANIZATION — a Organ— it3 Definition— Function,. 41 6 Apparatus, 41 c System, 41 d Organization— how defined, 41 FUNDAMENTAL ELEMENTS FORMING ORGANIZATION — 1. A Definite Origin or Generation, 42 2. A Definite Form, 43 3. A Definite Size, 43 4. A Definite and Peculiar Structure, 43 5. A Nutritive Fluid, 44 6. A Definite Nutrition, 44 7. A Dependency among the several Organs,. 44 8. A Limited Duration, 45 FUNDAMENTAL ELEMENTS PRESERVING ORGANIZATION — 1. Atmospheric Air, 45 2. Food 45 3. Water, 45 4. Heat, 45 RELATIONS BETWEEN THE ABOVE CLASSES OF ELEMENTS FIXED AND DETERMINED, 46 Obedience to which being rewarded with Health and Integrity of Organization , 46 Disobedience with Disease and Death, 46 VARIETIES IN ORGANIZATION, 47 Two great divisions—I. Vegetable, 41 2. Animal 47 VARIETIES IN ANIMAL KINGDOM — 1. Radiata— Zoophytes, 47 2. Articulata — Worms, Insects, 47 3. Mollusca— Shell Fish, 47 4. Vertebrata, 48 These varieties are so many types of different Organizations, and de- pend on many circumstances; for example, the Vertebrata are formed with special reference to one or more of the fundamental elements of preservation; as Fish are formed with reference to the Water, their special element,. . 48 Birds are formed with reference to the Air, 48 X CONTENTS. Reptiles to both Air and Water. " 48 Herbiverous Animals to special kinds of food; as Grass, Grain, Fruit, &c. 49 Carnivorous Animals to Flesh, , 49 SOME ORGANIZATIONS ARE FORMED WITH REFERENCE TO CLIMATE; as The Polar Bear for a Cold Climate, 49 The Ourang-Outang for a WarmC'limate, 49 This preference to Climate, and to one or more of the fundamental ele- ments, Air, Water, Food, &c., constitutes so many Special Laws of their Being and Existence. .-.. ,. , , THE LAST VARIETY OF ORGANIZATION is MAN, formed with reference to his Intellectual and Moral Faculties, 50 CONSTITUENTS OF HUMAN ORGANIZATION, 50 1. Chemical, 50 2. Organic, 50 Chemical— Oxygen, Hydrogen, Carbon, Nitrogen, 50 , Phosphorus, Lime, &c., 50 Organic — Protein, Albumen, Gelatin, Fibrin, Mucus, &c., 52 Union of these Elements constitutes the Solids and Fluids of the Body. ALL ORGANIZATIONS FORMED AND COMPLEX, in proportion to the num- ber and variety of the Powers, Properties and Functions they possess, 50 Man having most Functions, consequently most complicated, 50 DEVELOPMENT OF ORGANIZATION, 57 By Steps, , 57 TABLE OF POINTS OF DIFFERENCE BETWEEN INORGANIC AND ORGANIC BODIES, as given by M. Magendie, 57 ANATOMY — its Divisions, 58 PART FIRST. ALPHABET OF ANATOMY, OR ELEMENTARY TISSUES, 61 CHAPTER FIRST. ORIGIN OF TISSUES, 63 From the simple Cell or Vesicle discovered by Schwann in 1838, ... 63 Development of Tissues, 64 PHYSICAL PROPERTIES OF THE TISSUES,.. , . . . . 65 VITAL PROPERTIES OF THE TISSUES, 65 NUMBER OF TISSUES, >. . . . f)6 CHAPTF.R SECOND. THE BLOOD, 66 CHAPTER THIRD. THE CELLULAR TISSUE, 75 Adipose, 79 Serous, , 80 •j CONTENTS. XI Synovial,.. ." 82 Bursae Mucosae,. 82 CHAPTER THIRD. THE VASCULAR TISSUE, 83 Arterial, 94 Venous, 99 Lymphatic 105 CHAPTER FOURTH. THE NERVOUS TISSUE, 106 Animal Life, 106 Organic Life, 106 CHAPTER FIFTH. GLANDULAR TISSUE, t 117 CHAPTER SIXTH. CUTANEOUS TISSUE, 123 External or Skin, 123 Internal or Mucous Membrane, 123 CHAPTER SEVENTH. MUSCULAR TISSUE, 141 Voluntary, 142 Involuntary, 142 CHAPTER EIGHTH. FIBROUS TISSUE, ; 148 Ligaments, 150 Tendons, 153 Fibrous Envelopes, 154 CHAPTER NINTH. CARTILAGINOUS TISSUE, 156 CHAPTER TENTH. FIBRO-CAIITILAGINOUS TISSUE, ~. 159 CHAPTER ELEVENTH. ERECTILE TISSUE, 160 CHAPTER TWELFTH. OSSEOUS TISSUE, 161 XH CONTENTS. PART SECOND. THE HEAD. CHAPTER FIRST. PASSIVE ORGANS OF THE HEAD, BONES — 1 . Cranium, 177 2. Face, 196 SECTION I. BONES OF CRANIUM — Frontal, 177 Parietal, 180 Occipital, 182 Temporal , 184 Ethmoid, 189 Sphenoid, 192 General Remarks on the Cranium, 195 SECTION II. BONES OF THE FACE — Superior Maxillary, , 196 Palate 203 Malar, 205 Lachrymal, 206 Nasal, 207 Inferior Turbinated, 208 Vomer, 208 Inferior Maxillary, 209 Articulation of the Lower Jaw, 213 General Remarks on the Skull, 215 CHAPTER SECOND. ACTIVE ORGANS OF THE HEAD, 222 1. Organs of Digestion, 222 2. Organs of Expression and Speech, 222 3. Organs of Sense, 222 External 331 Internal, 386 4. Organs of Circulation 222 5. The Fascia, 222 ' ORGANS OF DIGESTION include those of Prehension, Mastication, Insaliva- tion and Deglutition, and belong to the Jtfouth. SECTION I. ORGANS OF PREHENSION — Mode of Dissection, 223 Levator Labii Superioris Alaeque Nasi, 224 Depressor Labii Superioris Alaeque Nasi, 224 Levator Anguli Oris, 224 CONTENTS. Depressor Anguli Oris,.. • 224 Levator Labii Inferioris, 225 Depressor Labii Inferioris, 225 Zygomaticus Major, 225 Zygomaticus Minor, 225 Buccinator, 225 Orbicularis Oris, 226 Combined Action of Muscles, 226 Blood Vessels, 226 Nerves,....* 227 SECTION II. ORGANS OF MASTICATION, 227 PASSIVE ORGANS OF MASTICATION — The Teeth, 227 Division into Temporary and Permanent, 228 Classification, 228 1. Incisors, 229 2. Cuspid or Canine, 230 3. Bicuspid, 232 4. Molar, 232 Description general of a Tooth, 229 Description of each Class of Teeth, 229 Microscopic Anatomy of the Pulp, 236 Eruption of Temporary Teeth, , 244 Eruption of Permanent Teeth, 245 Differences between Temporary and Permanent Teeth, 246 Differences between the Teeth and Bone, 247 Irregularities of the Teeth, 247 SECTION III. ORIGIN AND DEVELOPMENT OF THE TEETH, 248 FORMATION OF THE ENAMEL, 253 CHANGES PRODUCED IN THE UPPER AND LOWER JAW, OR FACE, FROM DE- VELOPMENT OF THE TEETH, 255 THE FUNCTIONAL RELATIONS OF THE TEETH, 258 VARIETIES OF TEETH, , 258 SECTION IV. BLOOD-VESSELS OF THE TEETH, 259 NERVES OF THE TEETH 262 SECTION V. COMPARATIVE ANATOMY OF THE TEETH, 268 EXTENT OF DENTAL ORGANS IN ANIMAL KINGDOM — GENERAL REMARKS ON DIFFERENT CLASSES — First Class— Mammalia, 270 Quadrumana, 273 Insectivora, 278 XIV CONTENTS. Cheiroptera, 279 Carnivora, 280 Marsupialia, 282 Rodentia,.... 282 Edentata, 283 Pachydermata, 283 Ruminantia, 288 Cetacea, 289 Second Class— A ves, 289 Third Class— Reptilia, 290 Fourth Class— Pisces, 292 Second Division of Animal Kingdom— The Invertebrata, 293 SECTION VI. ACTIVE ORGANS OF MASTICATION— Dissection,. 294 Masseter Muscle, 294 Temporal, 295 Pterygoideus Externus 296 Pterygoideus Internus, 297 Combined Action of Muscles, 297 Blood- Vessels, 298 Nerves, 298 SECTION VII. ORGANS OF INSALIVATION, 298 Dissection, 299 Parotid Gland, 299 Sub-Maxillary Gland 300 Sub-Lingual Gland, 301 Blood-Vessels, 302 Nerves 302 SECTION VIII. ORGANS OF DEGLUTITION, 303 MUSCLES— Dissection, 303 Digastricus, 304 Mylo-Hyoideus, 304 Genio-Hyoideus, 305 Genio-Hyoglossus, 305 Hyoglossus 306 Styloglossus, 306 Stylo- Hyoideus 306 SOFT PALATE— Velum Pendulum Palati 306 Situation, 306 Levator Palati, 308 Tensor Palati, or Circumflexus, 308 Constrictor Isthmi Faucium , or Palato-Glossus, 309 Palato-Pharyngeus, 309 Azygos-Uvulae, 309 CONTENTS. XV Blood- Vessels, 309 Nerves, 309 THE TONGUE, 310 Papillae — Papillae Maximse, or Circumvallatae, 311 Papillae Mediae, or Fungiformes, 311 Papilla? Villosse, 311 Papilla Filliformes, 311 Styloglossus Muscle, 306 Hyoglossus, 306 Genio-Hyoglossus, 305 Lingualis, 313. Blood-Vessels of Tongue, 313 Nerves of Tongue 314 PHARYNX 314 Situation , 314 Dissection, .315 Inferior Constrictor, 316 Middle Constrictor, 316 Superior Constrictor of the Pharynx, 316 Stylo-Pharyngeus, 316 Cavity of Pharynx, 317 Blood- Vessels of Pharynx, 317 Nerves of Pharynx, 318 SECTION IX. MOUTH, 318 Cavity of Mouth — Boundaries, 318 Organs composing it, 319 Mucous MEMBRANE OF MOUTH AND PHARYNX, 319 THE GUMS, 321 ALVEOLO DENTAL PERIOSTEUM, 322 BLOOD-VESSELS OF MOUTH AND PHARYNX, 323 NERVES OF THE MOUTH AND PHARYNX, 324 CHAPTER THIRD. ORGANS OF EXPRESSION, 324 Dissection, 324 Occipto-Frontalis Muscle, 324 Pyramidalis Nasi, 325 Corrugator Supercilii, 325 Compressor Nasi, 325 Orbicularis Palpebrarum, 326 Conjoint Action of Muscles, 327 Nerves— Portia-Dura of the Seventh Pair, 327 Blood-Vessels, 330 CHAPTER FOURTH. ORGANS OF SENSE, 330 External or Special Sensation 331 XVI CONTENTS. The Eye for seeing, 331 The Ear for hearing 331 The Tongue for tasting, 331 The Nose for smelling, 331 The Skin for touch, 331 SECTION I. THE EYE, 331 Division— 1. Eye proper, or Ball, 331 2. Appendages of the Eye, or Tutamina Oculi, 331 Ball of the Eye consists of a Membranous Case and four Refracting Media, 332 MEMBRANES OF THE EYE, 332 1. Sclerotic Coat, 332 2. Choroid, 334 3. Retina, 339 MEDIA OF THE EYE, 340 1. Cornea, 340 2. Aqueous Humor 342 3. Crystalline Lens, 343 4. Vitreous Humor, 345 Summary of Blood-Vessels and Nerves of the Ball of the Eye,. . . . 346 APPENDAGES OF THE EYE, 349 Muscles, 349 Rectus Superior, 349 Rectus Inferior, 350 Rectus Externus, 350 Rectus Internus, 350 Obliquus Superior, 350 Obliquus Inferior, 351 Levator Palpebrae Superioris and Tensor Tarsi, 351 Nerves of the Muscles of the Eye, 352 Eyebrows, 354 Eyelids, 355 Lachrymal Apparatus, 358 1. Lachrymal Gland, 358 2. Lachrymal Ducts,...* 359 3. Lachrymal Sac, 359 BLOOD-VESSELS OF THE EYE, 360 NERVES OF THE EYE, 360 SECTION II. THE EAR, 360 External, 361 Middle, 361 Internal Ear, 361 EXTERNAL EAR, 361 1. Pinna, 361 2. Meatus Externus, . . 361 CONTENTS. XVII MIDDLE EAR, 364 1. Membrana Tympani, 364 2. Ossicula Auditus, or Bones of the Ear 368 3. Muscles of Tympanum 369 INTERNAL EAR, OR LABYRINTH. 370 1 . Vestibule, 370 2. Cochlea, 371 3. Semi-circular Canals, 373 Nerves of Ear, 375 Blood-Vessels of Ear, 376 General Remarks, 377 SECTION III. THE TONGUE, Organ of Taste, 377 Structure — see Organs of Deglutition, 310 Physiology of Taste, 379 SECTION IV. THE NOSE, Organ of Smell, 379 1. Cartilages, 380 2. Nasal Fossae, 381 3. Pituitary Membrane, 383 4. Blood-Vessels of Nose, 383 5. Nerves, 383 SECTION V. THE SKIN, Organ of Touch, 384 Structure, 385 Physiology of Touch, 386 CHAPTER FIFTH. INTERNAL ORGANS OF SENSE, 386 CEREBRO SPINAL Axis, 386 Division — Dissection from below: 1. Spinal Marrow, 387 2. Brain, 392 SECTION I. SPINAL CORD, 387 Situation, 387 Membranes, 387 Division into Rods or Columns, 390 Nerves, 391 SECTION II. THE BRAIN, 392 Situation, 392 Membranes,. 393 2A CONTENTS. 1. Dura-Mater, ............................................. 393 2. Tunica Arachnoidea, ..................................... 398 3. Pia Mater, ..................... . ........................ 399 4. Sinuses, ................................................. 396 DIVISION OF THE BRAIN, ............................................ 392 1. Medulla Oblongata— Situation, ................................. 400 g ....Divided into— Corpora Pyramidalia, ........................... 401 Corpora Olivaria, .............................. 401 Corpora Restiformia, ........................... 401 Nerves, ........................................ 402 2. Pons Varolii, ................................................ 402 3. Cerebellum, ................................................. 403 Situation, ................................................ 403 Surfaces, ................... . ............................. 404 Structure, ................................................ 406 4. Cerebrum, ................................................... 408 Situation, ................................................. 408 Surface, .................................................. 408 Divided into Hemispheres, ................................. 408 Lobes, ................................................... 408 Nerves, ....... . .......................................... 420 Blood-Vessels, ............................................. 425 SECTION III. BLOOD-VESSELS OF HEAD IN NUMERICAL ORDER, ......................... 428 SECTION IV. TABLE or MUSCLES OF THE HEAD, .................................... 435 CHAPTER SIXTH. ANATOMICAL AND PHYSIOLOGICAL RELATIONS OF THE MOUTH WITH THE DIFFERENT PARTS or THE HEAD, ....... . ...................... ... 437 PART THIRD. THE TRUNK— ITS ORGANS, ACTIVE AND PASSIVE. CHAPTER FIRST. PASSIVE ORGANS — THE BONES, 443 1. Spine, 443 2. Thorax, 443 3. Pelvis, 443 N. SECTION I. SPINB, OR VERTEBRA, , 443 1. Cervical Vertebrae, 446 2. Dorsal Vertebra, 449 CONTENTS. 3. Lumbar Vertebra, 450 4. Pelvic Vertebrae— Sacrum, 451 Coccyx, 453 5. Ligaments of the Spine 454 SECTION II. THORAX, OR CHEST, 460 1. Sternum, 460 2. Ribs, 463 3. Cartilages of Ribs, 465 4. Ligaments of the Chest, 466 5. General Remarks upon the Chest, 468 SECTION III. PELVIS, 470 Innominata, 470 Ilium, 470 Ischium, 472 Pubis, 473 Ligaments,.. 475 Differences between Male and Female Pelvis, 479 CHAPTER SECOND. ACTIVE ORGANS OF THE TRUNK, 481 FIRST DIVISION. ORGANS BELONGING TO THE NECK AND BACK, 481 1. The Organs of Motion— Muscles, 481 2. Organs of Deglutition — CEsophagus, 481 3. Organs of Circulation— Blood-Vessels, 481 4. Organs of Innervation — The Nerves, 481 5. Fascia of the Neck, - 481 6. Lymphatic Glands, 481 7. Thyroid Gland, 481 8. Organ of Voice — Larynx, 481 SECTION I. ORGANS OF MOTION 481 Muscles of the Anterior Neck, 481 Dissection, 481 Platisma Myoides, 482 Sterno Clido Mastoideus, 482 Sterno Hyoideus, 483 Sterno Thyroideus, 484 Omo Hyoideus, 484 Triangles of the Neck, 485 Scalenus Anticus, 486 Scalenus Medius, k 486 Scalenus Posticus, 486 XX CONTENTS. Longus Colli f 487 Rectus Capitis Anticus Major, 487 Rectus Capitis Anticus Minor, 487 Rectus Capitis Lateralis, 488 SECTION II. MUSCLEI OF THE POSTERIOR NECK AND BACK,.. 488 Dissection, ' 488 First Layer, 488 Trapezius, 488 Latissimus Dorsi, 489 Second Layer, 490 Dissection, 490 Rhomboideus Minor, 490 Rhomboideus Major, 490 Levator Anguli Scapulae, , 490 Third Layer, 491 Dissection, 491 Serratus Posticus Superior, 491 Serratus Posticus Inferior, 492 Splenius Capitis et Colli, , 492 Fourth Layer, 492 Dissection, 492 Sacro Lumbalis, 492 Longissimus Dorsi, 493 Spinalis Dorsi, 493 Cervicalis Ascendens, 493 Transversalis Colli, 494 Trachelo Mastoideus, 494 Complexus, 494 Fifth Layer, 494 Dissection, 494 Rectus Capitis Posticus Major, 494 Rectus Capitis Posticus Minor, 494 Obliquus Capitis Superior, , 495 Obliquus Capitis Inferior, 495 Semi Spinalis Colli et Dorsi, 495 Sixth Layer, 496 Dissection, 496 Inter Spinales, 496 Inter Transversales, 496 Multifidus Spinae, 496 Levatores Costarum 496 Supra Spinales, 496 SECTION III. ORGANS OF DEGLUTITION 497 Oesophagus, 497 Pneumogastric Nerve,. 498 CONTENTS. XXI SECTION IV. ORGANS OF CIRCULATION, OR THE BLOOD-VESSELS OF THE NECK 501 Arteries — Common Carotid, 501 External Carotid, 503 Branches of External Carotid, 503 Superior Thyroid, 503 Facial, 504 Occipital, 504 Subclavian Arteries, at the Lower Part of the Neck, 504 Branches supplying Neck — 1. Vertebral, 505 2. Thyroid Axis, 506 Inferior Thyroid, 506 Superior Scapular, 506 Posterior Scapular, 507 Cervicalis Anterior, 507 3. Cervicalis Posterior, or Profunda Cervicis,. 509 Veins — The Jugulars — External Jugular ?V 507 Internal Jugular, 508 Subclavian Veins, 509 SECTION V. ORGANS OF INNERVATION, OR THE NERVES OF THE NECK, 509 Par Vagum, 509 Spinal Accessory, 509 Lingual 510 Facial 511 Cervical Plexus, 511 Phrenic Nerve, 512 Brachial Plexus, 513 Sympathetic and its Ganglia,... 514 SECTION VI. FASCIA OF THE NECK, 522 Lymphatic Glands, 523 Thyroid Gland, 524 SECTION VII. ORGAN OF VOICE— The Larynx, 525 1. Cartilages — Thyroid, 525 Cricoid, 526 Arytenoid, 526 Epiglottis, 527 2. Ligaments, 527 Muscles — Thyro Hyoideus 529 Crico Thyroideus, 529 XXH CONTENTS. Thyro Arytenoideus 530 Crico Arytenoideus Posticus, 530 Crico Arytenoideus Lateralis, 530 Arytenoideus Obliquus, 531 Arytenoideus Transversus, 531 Thyro Epiglottideus, 531 Aryteno Epiglottideus, 531 Mucous Membrane of Larynx and Glands 532 Blood- Vessels of Larynx 533 Relations of Larynx, 533 Physical, 533 Organic, 533 Men tal , 533 Trachea, 534 CHAPTER THIRD. SECOND DIVISION. ACTIVE ORGANS OP TRUNK, 537 ORGANS OF ABDOMEN, 537 General Observations, 537 Boundaries of Abdomen, 537 Regions of Abdomen, 537 Organs or Viscera in each region, 538 Walls of Abdomen, 539 SECTION I. Dissection— Anterior Walls— Obliquus Externus, 539 Obliquus Internus, 542 Transversalis, 543 Rectus Abdominis, 544 Pyramidalis 545 Posterior Walls — Quadratus Lumborum, 549 Psoas Muscles, 550 Superior Wall— Diaphragm, 551 Inferior Wall— Pelvis, 470 SECTION II.' ORGANS OF ABDOMINAL DIGESTION, 554 Organ of Chymification — The Stomach 558 Organs of Chylification— 1. Membranous; 2. Glandular- Membranous— Small Intestine— Duodenum, 565 Jejunum, 568 Ilium, 568 Organ of Faecation— Large Intestine, 571 1. CoBcum, 572 2. Colon, 573 3. Rectum, 573 CONTENTS. XXIII Glandular or Assistant Organs of Digestion, 576 1. Liver 576 2. Pancreas, 586 3. Spleen, 589 SECTION III. ORGANS OF ABSORPTION OF THE TRUNK, 590 CHAPTER FOURTH. THIRD DIVISION. ORGANS OF THE CHEST, 596 SECTION I. MUSCLES OF THE CHEST, 597 Dissection, 597 Pectoralis Major, 597 Pectoralis Minor, 598 Serratus Major Anticus, 598 Intercostales, External and Internal, 599 Subclavius, 600 Triangularis Sterni, 600 Pleura, 602 SECTION II. ORGANS OF RESPIRATION, 605 Larynx, 605 Trachea, 605 Bronchi, 609 Lungs, 605 Thy mus Gland, 613 ORGANS OF CIRCULATION, 614 Heart and Pericardium, 614 Aorta and Branches, 626 Vena Cava, Superior and Inferior, 627 Vena Azygos, 628 Nerves of Thorax and Abdomen, 629 CHAPTER FIFTH. FOURTH DIVISION. ACTIVE ORGANS OF TRUNK, 637 ORGANS OF URINATION, 637 SECTION I. KIDNETS, 637 SECTION II. URETERS, 643 SECTION III. BLADDER 643 XXIV CONTENTS. CHAPTER SIXTH. FIFTH DIVISION. ORGANS OF THE PELVIS, INCLUDING — 1. Male Organs of Generation, 649 2. Female Organs of Generation, 661 SECTION I. MALE ORGANS — Testes, 649 Vesiculoe Seminales, 655 Prostate Gland, 655 Penis, 656 SECTION II. FEMALE ORGANS, 66 1 External Organs of Generation 661 Vagina, 664 Uterus, .-. 665 Ovaries, 669 SECTION III. MUSCLES OF THE PELVIS, 672 Gluteii, 672 Maximus, 672 Medius, 673 Minimus, 673 Rotators — Pyriformis 674 Gemini, Superior and Inferior, 674 Obturator Internus, 674 Obturator Externus, 674 Quadrator Femoris, 675 SECTION IV. FASCIA OP PELVIS, 675 SECTION V. PERINEUM OF THE MALE, 676 Dissection, 676 Muscles— Sphincter Externus, 678 Sphincter Internus, 678 Erector Penis, 678 Accelerator Urinse, 679 Transversus Perinei, 679 Coccygeus 679 Levator Ani, 679 Blood-Vessels and Nerves, 680 SUMMARY OF BLOOD-VESSELS AND NERVES OF TRUNK, 681 SECTION VI. ANATOMICAL AND PHYSIOLOGICAL RELATIONS OF THE MOUTH WITH THE DIFFERENT ORGANS OF THE TRUNK, . „ 684 CONTENTS. XXV PART FOURTH. THE EXTREMITIES. 1. SUPERIOR EXTREMITY, 690 2. INFERIOR EXTREMITY, * 742 SUPERIOR EXTREMITY. CHAPTER FIRST. THE PASSIVE ORGANS — THE BONES— 1. Bones of the Shoulder, 689 2. Arm, 692 3. Forearm, 694 4. Hand,.. 697 SECTION I. SHOULDER — 1. Scapula, 689 2. Clavicle, 691 SECTION II. HUMERUS OR ARM BONE, • 692 SECTION III. FOREARM,.. 694 1. Radius, 694 2. Ulna, 696 SECTION IV. HAND, 697 1. Carpus, 697 2. Metacarpus 699 3. Phalanges, 701 SECTION V. LIGAMENTS OF THE SUPERIOR EXTREMITY — Sterno Clavicular Articulation, 702 Costo Clavicular Articulation, 703 Scapulo Clavicular Articulation, 703 Ligaments of the Scapula, 703 Arm, 704 Forearm, » . . . 705 Hand, 706 Carpus, 706 Metacarpus, 708 Phalanges, 709 2B XXVI CONTENTS. CHAPTER SECOND. ACTIVE ORGANS OF THE SUPERIOR EXTREMITY, 709 SECTION I. MUSCLES OF THE SUPERIOR EXTREMITY, 709 Of the Shoulder, 709 Deltoid, 710 Supra Spinatus 710 Infra Spinatus, 710 Teres Minor, 711 Teres Major, 711 Sub Scapularis, 711 Of the Arm, 712 Biceps Fiexor Cubiti, 712 Coraco Brachialis 713 Brachialis Anticus, 713 Triceps Extensor Cubiti, 713 Anconeus, 714 Of the Forearm, 714 Pronator Radii Teres, 715 Flexor Carpi Radialis, 715 Palmaris Longus, 715 Flexor Carpi Ulnaris, 716 Flexor Digitorum Sublimis Perforatus, 716 Flexor Digitorum Profundus Perforans, 716 Flexor Longus Pollicis, 717 Pronator Quadratus, 717 Supinator Radii Longus, 717 Extensor Carpi Radialis Longior, 718 Extensor Carpi Radialis Brevior, 718 Extensor Digitorum Communis, 719 Extensor Carpi Ulnaris, 719 Supinator Radii* Brevis, 719 Extensor Ossis Metacarpi Pollicis, 720 Extensor Major Pollicis, 720 Extensor Minor Pollicis, 720 Indicator, 720 Of the Hand, 722 Abductor Pollicis, 722 Opponens Pollicis, 722 Flexor Brevis Pollicis, 722 ' Adductor Pollicis, 723 Abductor Indicis, 723 Adductor Minimi Digiti, i 723 Abductor Minimi Digiti, 723 Flexor Brevis Minimi Digiti, 723 Palmaris Brevis, 723 Interosseous Muscles, 724 CONTENTS. XXVH SECTION II. FASCIA OF THE SUPERIOR EXTREMITY, 724 SECTION 111. BLOOD-VESSELS OF THE SUPERIOR EXTREMITY, •• 726 Arteries of the Shoulder,. , 727 Axillary Artery, 727 Branches — Thoracica Acroraialis, 728 Inferior Thoracic, 728 Thoracica Axillaris, 728 Subscapular Artery, 728 Anterior Circumflex, 728 Posterior Circumflex, 729 Arteries of the Arm, 729 Brachial Artery, 729 Profunda Superior, 729 Profunda Inferior, 730 Anastomotica Magna, 730 Muscular Branches, 730 Arteries of the Forearm, 731 Radial Artery, 731 Branches — Recurrens Radialis, 731 Muscular Branches, 731 Superficial Volas, 731 Dorsalis Carpi, 731 Radialis Indicis, 731 Magna Pollicis, 731 Ulnar Artery 732 Branches — Recurrens Ulnaris, 732 Interosseous Artery, 733 Anterior Interosseal Artery, 733 Posterior Interosseal Artery, „ . . . 733 Dorsalis Carpi Ulnaris, 733 Arteries of the Hand, 733 Arcus Superficial, 733 Digital Arteries, 733 Arcus Profundus 734 Veins of the Superior Extremity — Cephalic Vein, 735 Basilic, 735 Median Vein, 736 Axillary Vein,. . 736 NERVES OF THE SUPERIOR EXTREMITY, 736 Axillary Plexus, 736 Branches— Thoracic Nerves, 737 Supra Scapular, 737 Sub Scapular, 737 Internal Cutaneous, 738 External Cutaneous, 739 Circumflex. . 739 XXVm CONTENTS. Median, 739 Ulnar 740 Radial Nerves, 740 Intercosto-humeral Nerves, 741 SUMMARY OF THE MUSCLES OF THE SUPERIOR EXTREMITIES, 741 INFERIOR EXTREMITY. CHAPTER FIRST. BONES AND LIGAMENTS, 742 SECTION I. BONE OF THE THIGH, «... 742 Os Femoris, 742 SECTION II. BONES OF THE LEG, 745 Tibia, 745 Fibula, 746 Patella, 747 SECTION III. BONES OF THE FOOT, 748 Tarsus, 748 Metatarsus, 750 Phalanges, 751 SECTION IV. LIGAMENTS OF THE INFERIOR EXTREMITIES, 751 Ligaments of the Hip Joint, 751 Ligaments of the Knee Joint, 752 Ligaments of the Ankle Joint, 755 Ligaments of the Foot, 756 CHAPTER SECOND. ACTIVE ORGANS OF THE INFERIOR EXTREMITIES, 757 SECTION I. MUSCLES OF THE INFERIOR EXTREMITIES, 757 Muscles of the Thigh, 757 Anterior and Inner Thigh — Sartorius, 758 M ;.- 1 Rectus Femoris, 758 Vastus Externus, 759 Vastus Internus 759 Cruraeus, 759 G racilis, 759 Pectineus 760 Adductor Longus, 760 CONTENTS. XXIX Adductor Brevis, 760 Adductor Magnus, 760 Outer Thigh— Tensor Vaginae Femoris, < 758 Posterior Thigh — Biceps Flexor Cruris, 761 Semitendinosus, • 761 Semimembranosus , 671 Muscles of the Leg, 762 Anterior and Outer Leg — Tibialis Anticus, 762 Extensor Communis Digitorum Pedis, 762 Extensor Proprius Pollicis, 763 Peroneus Longus, 763 Peroneous Brevis, 763 Peroneus Tertius 764 Posterior Leg — Gastrocnemius 764 Plantaris, 765 Popliteus, 765 Flexor Communis Digitorum Pedis, 765 Flexor Longus Pollicis, 766 Tibialis Posticus, 766 Muscles of the Foot, 766 First Layer— Abductor Pollicis Pedis, 766 Abductor Minimi Digiti 767 Flexor Brevis Digitorum, 767 Second Layer — Flexor Accessorius, 767 Lumbricales Pedis, 767 Third Layer— Flexor Brevis Pollicis, 768 Adductor Pollicis, 768 Flexor Brevis Minimi Digiti, 768 Transversalis Pedis, 768 Fourth Layer— Interosseii Plantares, 769 Dorsum of Foot— Interosseii Dorsales, • • • • 769 Extensor Brevis Digitorum Pedis, 766 SECTION II. FASCIA OF THE INFERIOR EXTREMITY, 769 Superficial Fascia, 769 Fascia Lata, 769 SECTION III. BLOOD-VESSELS OF THE INFERIOR EXTREMITIES, 772 Arteries.— Femoral Artery, 772 Branches— Superficial Epigastric, 773 Superficial Circumflexa Ilii, 773 External Pudic 773 Profunda Femoris, 773 External Circumflex, 773 Internal Circumflex, ; . . . 774 Perforating Arteries, 774 Anastomotica Magna, 774 XXX CONTENTS. Popliteal Artery, 774 Branches— Muscular Branches, 775 Superior Articular, 775 External, 775 Internal, 775 Inferior Articular, 775 External, 775 Internal 775 Middle Articular, 775 Gastrocnemial Branches, 775 Anterior Tibial Artery,- 775 Branches — Recurrent Tibial, 776 Muscular Branches 776 Malleolar, 776 Internal, 776 External, 776 Metatarsal, 776 Arteria Pollicis, 776 Communicans, 776 Posterior Tibial Artery, 776 Branches — Peroneal Artery, 776 Muscular Branches, 777 Nutritious Artery, 777 Plantar Arteries, 777 Internal, 777 External, 777 Digital Arteries, 777 Veins of the Inperior extremity, 778 Saphena Vein — Internal, 778 External 778 Tibial Veins— Anterior, 778 Posterior, 778 Peroneal Veins, 778 Popliteal Vein, 778 Femoral Vein 778 SECTION IV. NERVES OF THE INFERIOR EXTREMITY, 779 Anterior Crural Nerve— Muscular Branches, 779 Internal Saphenus, 779 Sacral Plexus — Branches— Lesser Sciatic Nerve, 780 Cutaneous Branches 780 Gluteal, 781 Great Sciatic, 781 Popliteal Nerve, 781 Posterior Tibial, 782 Peroneal 783 SUMMARY OF THE MUSCLES OF THE INFERIOR EXTREMITIES, 784 ANATOMICAL AND PHYSIOLOGICAL RELATIONS OF THE MOUTH WITH THE EXTREMITIES, 785 LIST OF ILLUSTKATIONS. no. PAGE 1 Nucleated cell, ...................... 63 2 Blood corpuscle, ..................... 71 8 Cellular tissue, ...................... 76 4 Adipose tissue, ...................... 79 5 Capillary tissue, ...................... 84 6 Portal circulation, .................... 87 7 General circulation, .................. 89 8 Distribution of the arteries, ........... 95 9 Venous circulation, .................. 100 10 Heart, ............................... 102 11 Double heart, ........................ 103 12 Foetal circulation, .................... 105 3 Minute structure of nerve, ............ 108 14 Spinal marrow, ...................... 112 15 Spinal marrow, section of, ........... 113 16 Brain, ............................... 114 17 Mammary gland, .................... 118 18 Thoracic duct, ....................... 121 19 Skin, structure of, .................... 125 20 Epithelium scales, ................... 135 21 Columnar epithelium, ................ 136 22 Ciliated epithelium, .................. 136 23 Gastric pits, ..... .7 .................. 138 24 Brunner's glands .................... 138 25 Peyer's glands, ...................... 138 26 Muscular fibre of animal and organic life, .............................. 144 27 Attachment of tendon to muscular fibre, 147 23 White and yellow fibrous tissue, ...... 149 29 Cartilage corpuscles, ................ 153 30 Texture of bone,...? ................. 16? oo Concentric Lamella} of bone, ......... 168 62, Haversian canals, .................... 169 Frontal bone, front view, ............. ITS »4 S rontal bone, inner view, ............ 178 b5 J rontal bone, lower portion, .......... 179 ) 1 arietal bone, outer surface, .......... ISO . 1 arietal bone, inner surface, .......... 181 W Occipital bone, outer surface, ......... 182 Occipital bone, inner surface, ......... 183 10 iemporal bone, outer surface, ........ 185 L Iemporal bone, inner surface, ........ 186 Jkthmoid bone, ....................... 189 43 Sphenoid bone, ............... * 191 Malar bones,'. ..... V. .V.V. .V.V.V.V '.V. 2 Lachrymal bones, (os unguis,) ....... 206 Nasal bones, ........... ........ 207 Inferior turbinated bones, ....... '.'.'.'.". 208 v omer, ....................... 208 Inferior maxillary bone,."..".'.'." " 209 ArHCaiat|on of lower juw, ..... 21o Sutures of the cranium,..' ....... Base of the cranium'. Muscles of the face, .'...... ....... |l| Articu'ation of the teeth, ...... Incisor teeth, .......... Cuspidali...... .............. 5 Bi-cuspidati, ...... '. ............ 90 Molars,.... '......... ................. |fj Structure and pulp cavities of teeth,'.!'. 285 Blood-vessels of pulp,. . . . oo,5 Nerves of pulp, . .. . J ) ..... / Cellular arrangement of the pulp " !. Baccated view : of the dentine,.... ..... 237 Blood.-vessels of dentine, ...... . 240 Dentine according to Mr. Tomes, ..... 242 FIG. 68 Enamel fibres, ...................... 69 Temporary teeth, ................... 70 The two sets of teeth, ................ 71 Origin and progress of the teeth, ..... 72 Different structures of a toolh, ........ 73 Arteries of the face, ................. 74 Fifth pair of nerves, ................. 75 Dental arch of Chimpanzee, ......... 76 Deciduous and permanent teeth of the dog, ............................. 77 Deciduous and permanent teeth of the bear, ............................. 78 Deciduous and permanent teeth of the hog, .......... • ................... 79 Section of the incisor of a horse, ...... 80 Poison fangs of serpents, ............ 81 Teeth of the rock fish, ............... 82 Muscles of the face, ................ 83 Temporal muscle, ................... 84 Pterygoid muscles, .................. 85 Salivary glands, ..................... 86 Muscles of the lower jaw, ............ 87 A side view of the tongue, ........... 88 Muscles of the soft palate, ........... 89 The tongue, ........................ 90 Papillae of the tongue, ............... 91 Nerves of the tongue, ............... 92 The pharynx, ..................... 93 Cavity of the mouth, ................ 94 Glands of the lips, .................. 95 Vascularity of the lips, ............. 96 Papilla? of the gums, ................ 97 Facial nerve, ....... ................ 98 The eye...... .................. .... 99 The eye— transverse section, ........ 100 The retina, ................ . ........ 101 Nerves of the eyeball, ............... 102 Muscles of the eyeball, ............... 103 Meibomian glands, .................. 104 Lachrymal apparatus, ............... 105 The external ear, ................... 106 External, middle, and internal ear,. . . 107 Little bones of the ear, .............. 108 Labyrinth of the ear, ................ 1 09 Labyrinth of the ear, , ............... 110 Olfactory nerves, ................... 111 Nasal Fossae, ....................... 1 12 Sinuses of the dura mater, ........... 113 Cerebellum, ....................... 114 Arbor vibe, ......................... 115 Convolutions of cerebrum, ........... 116 Longitudinal section of the brain, ____ 117 Horizontal section of the brain, ....... 118 Optic nerves ........................ 119 Circle of Willis, ..................... 120 Branches of external carotid, ........ 121 Internal maxillary artery, ........... 122 Spinal column, . .. ..... ... ...... 123 A lumbar vertebra, ................ . 124 Cervical vertebne, ....... 125 The atlas, ....... ! ....... 126 Thedentata, ....................... 1 27 Seventh cervical vertebrae ........ 128 A dorsal vertebra, ....... . ......... 129 A lumbar vertebra, ................. 180 Sacrum, ....... 131 Coccyx, ................. '.".'.".".V.V..".'.' 132 Anterior vertebral ligament, ......... 243 244 245 249 254 260 263 274 280 281 235 28T 091 292 294 295 ong 299 304 305 QAT 310 312 014 £} 313 3^9 320 321 339 345 349 357 353 361 371 875 380 882 39T 404 405 409 413 415 401 4|g 423 400 ! 443 443 450 451 2w 454 455 XXXH LIST OP ILLUSTRATIONS. 183 Posterior vertebral ligament, • 455 134 Yellow ligaments, 456 185 Ligaments of atlas and dentata, 458 136 Ligaments of atlas and dentata, 459 137 Sternum and ribs, 461 138 Ribs, 463 139 First rib, 464 140 Ligaments of the ribs, 467 141 Ligaments of sternum and ribs, 467 142 Os innominatum, 470 148 Ligaments of the pelvis, 476 144 Ligaments of the pelvis, 477 145 Diameters of the pelvis, 480 146 Superficial muscles of the neck, 481 147 Muscles of the neck, 483 148 Deep muscles of the neck, 486 149 Muscles of the neck and back, 489 150 Muscles of the back, 491 151 Muscles ot the back, 493 152 The eighth pair of nerves, 498 153 Blood-vessels and nerves of anterior neck,..." 502 154 Veins of the neck 508 155 Sympathetic nerve, 515 156 Cranial ganglia, 517 157 Orig n of sympathetic nerve, 519 158 Thyroid cartilage, 525 159 Cricoid Cartilage, 526 160 Arytenoid cartilages, 526 161 Epiglottis, 527 162 Muse es of the larynx, 529 163 Muscles of the larynx, 530 164 Muscles of the larynx, 530 165 The trachea, 535 166 Eegions of the abdomen, 538 167 Muscles of the abdomen, 540 168 Inguinal Hernia, 541 169 Transversalis muscle, 544 170 Internal abdominal ring, 547 171 Blood- vessels of ant'r abdominal wall, 548 172 Muscles of posterior abdominal wall, . 549 178 The diaphragm, 552 174 Reflections of the peritoneum, 555 175 Stomach and intestines, 559 176 Coats of the stomach, 560 177 Interior of the stomach, 561 178 Gastric favuli, S62 179 Gastric glands, 562 180 Arteries of stomach, 564 181 Duodenum, 565 182 Lacteal tube, 567 183 Glands of Brunner, 568 184 Ilium, colon and mesentery, 569 185 Large intestine, 571 186 Anus, section of, . 575 187 The liver, 576 188 Venaporta, 580 189 Lobules of the liver, 583 190 Lobules of the liver, 684 191 The pancreas, 586 192 The spleen, 589 193 Serratus major anticus, 599 194 Lactiferous ducts, 602 195 The pleura, .. 603 196 The lungs, 606 197 The lungs and heart, 608 198 Cavities of the heart;. 616 199 Right heart, 617 200 Left ventricle, 621 201 Muscular fibres of the heart, 622 202 Connection of sympathetic with spinal nerve, 680 203 Plexuses of sympathetic nerves, 632 204 Lumbar and ischiatic plexuses, 634 205 Urinary apparatus, 638 206 Section of kidney, 639 207 Urinary bladder, 644 208 Testicle, transverse section of, 650 209 Testicle, structure of, 652 210 Penis and bladder, 65T 211 Female organs of generation, 664 212 Muscles of the pelvis, 672 213 Male perineum, 677 214 Blood-vessels of the trunk, 688 215 The scapula, 690 216 The clavicle, 691 217 The humerus, 693 218 Radius, ulna, 695 219 The carpus, 698 220 Metacarpus, phalanges, 700 221 Ligaments of shoulder joint, 704 222 Elbowjoint, 706 223 Wrist joint, 707 224 Muscles of the shoulder, 711 225 Muscles of the arm, 712 226 Triceps muscle, 714 227 Muscles of the forearm, 715 228 Muscles of the forearm, 71T 229 Muscles of the forearm, 718 230 Muscles of the forearm, 720 231 Extensor accessorius indicis, 721 232 Muscles of the hand, 722 233 Axillary artery and nerves, 727 234 Brachial artery and nerves, 730 235 Radial and ulnar arteries, 732 236 Arteries of the hand, 734 287 Veins of superior extremity, 735 288 Nerves of superior extremity, 737 239 Cutaneous nerves of elbow joint, 738 240 Os Femoris, 743 241 Tibia and Fibula, 745 242 The patella, 747 243 Bones of the foot, 748 244 Ligaments of hip joint, 752 245 Ligaments of knee joint, 753 246 Ligaments of knee joint, 754 247 Ligaments of ankle joint, 755 248 Ligaments of foot, 756 249 Muscles of thigh, 758 250 Muscles of thigh, 761 251 Muscles of leg, 762 252 Muscles of leg, 764 253 Muscles of leg, 765 254 Muscles of foot, 767 255 Muscles of foot, 768 256 Muscles of foot, 769 257 Femoral artery, 773 258 Popliteal artery, 774 259 Anterior tibial artery, 775 260 Arteries of the foot, 777 261 Saphena vein, 778 262 A nterior crural nerve, 780 268 Sacral plexus, 781 264 Plantar nerves, 783 Errata. — A few typographical errors have occurred in the printing of the work, which the attentive reader will be able to correct. INTRODUCTION , HISTORY OF ANATOMY. ALL that we propose, under the present head, is simply to give a very brief outline of the Art of Dissection, for the purpose of showing, by way of contrast, its past and present state. The Art of Dissection appears to be of great antiquity, it being the custom to sacrifice animals to the Deity, some parts being set aside for the sacrifice, and others for the use of the priests. It hence became necessary to discriminate, or distinguish the one from the other. This kind of know- ledge, however, belonged to Comparative Anatomy, and at that day was mostly confined to the butchers. It is supposed that the cruel custom of human sacrifices originated the first information we have of the human body; for in such cases it was necessary that some knowledge of the internal structure of the human frame should be ac- quired by the priests, that they might properly conduct such ceremony. The first attempt at making Anatomy a science, is ascribed to Pythagoras, and Tholes of Miletum, about 700 years before Christ, who, we are told, made it a part of their studies. Empedocles, about 100 years after this, showed considerable Anatomical knowledge, especially in reference to the coddea and tube of the ear. The first who dissected animals, with a view to learning their internal structure, was Alcmeeon, a disciple of Py- 3 34 INTRODUCTION. thagoras. But it is to Hippocrates, who is styled the father of medicine, that we are directed to look, as being the pos- sessor of all the Anatomy known in his day, which was about 500 years before Christ. This knowledge, if such it may be called, though it abounded in errors, and in a great measure necessarily so, from the dissections being mostly confined to inferior animals, and from the supersti- tions of the age, and insuperable obstacles constantly oppo- sing human dissections : we say, in view of all this, we cannot refrain uniting in the language of an author, "that the perseverance and acquirements of this great man, the ornament of the medical profession, cannot be sufficiently admired." A few specimens of his Anatomical knowledge will here suffice. The left ventricle of the heart he supposed the seat of the soul. The arteries he thought conducted the spirits. The liver he believed to be the fountain of the blood, and the root of the veins. The heart and lungs he supposed received part of our drink. The auricles were believed to serve the purpose of a fan; and no distinction was made between arteries, veins, nerves and tendons. After Hippocrates, the study of Anatomy seemed to be chiefly confined to the two schools of Athens and Alexandria. To the former belong the names of Socrates, Plato, Xeno- phon, Aristotle and Theophrastus. And although their attention was principally directed to the study of Philosophy, yet a knowledge of Anatomy was not overlooked, though the examination of bodies was very much restricted. In the Alexandrian school, however, Anatomy greatly flourished. It received the protection, favor, and presence of the Ptolemies. Anatomy was here publicly taught. Dissections of human bodies were made, and we are in- formed that kings were sometimes present at them. Hero- philus and Erasistratus were the distinguished masters of Anatomy in this school. We are told that they dissected several hundred bodies, and were especially famous for their productions in Neurology. From Herophilus and Erasistratus, to Galen, embracing a INTRODUCTION. 35 period of 500 years, trie names of Asdepiades, Eufus Ephese- uSj and Celsus, stand most prominent. The two latter gave the names and localities to many parts of the body. Clau- dius Galenus or Galen appeared and flourished about the close of the second century. He was considered one of the most remarkable and learned men that ever lived. He applied himself especially to the investigation of Anatomy, but, unfortunately, his descriptions were mostly taken from the brute creation. In his works, Anatomy is made to occupy a prominent and methodical place, and for 1500 years his name and influence reigned supreme, in spite of all his errors; so much so, that it was considered the very height of medical folly even to suspect, and a far more unpardonable presumption to call in question and attempt to correct any of his opinions. A treatise "on the nature of man," is recorded as being the production of Nemesius, Bishop of Emissa, who wrote about the end of the fourth century, his most prominent Anatomical claim being the discovery of the use of the bile. From the period of Galen to the 16th century, Anatomy, with every other kind of learning, was on the decline. Du- ring this long lapse of what has been very significantly styled the Dark Ages, very little or no improvement was made. After the destruction of Alexandria, learning, as much as was left, was introduced among the Arabians, and they applied themselves to the study of "physic;" but, as their law, like that of the Jew, prohibited dissections, of course they could make but little improvement. In the llth century, the school of Salernum, in Sicily, was established, and obtained considerable reputation. But owing to the ignorance and superstition of the times, and from its being viewed as a "crime" to dissect a human body, this school did little more than teach the dogmas of the Arabian doctors. About the close of the 12th century, Abdollalliph distin- guished himself in osteology, by exposing many of the errors of Galen in this department. 36 INTRODUCTION. In the commencement of the 14th century, Mundinus is represented as the first European author who insisted upon dissections, and whose system of instruction was of so high repute, as to be taught for years in the schools. Even in the University of Padua, the Professors were obliged, by a law of the College, to make this system their text- book. Towards the close of the 15th century, Jacobus Beren- garius Carpus revived dissections, and published two Ana- tomical works, one of which was simply a commentary on Mundinus. The 16th century teems with improvements and discov- eries in anatomy, from men of the most exalted talent, untiring industry, and self-sacrificing devotion to this, their favorite pursuit. Italy for a long time seemed ttf be the sole theatre of Anatomical knowledge. About the year 1536, however, John Gruinterius, who had been a teacher of Anatomy for several years in Paris, published a work entitled "Anatomicse Institutiones," in which, it is said, he has given a pretty full and accurate description of the muscles. But it is most especially to that great man, Andreas Vesa- UuSj of Brussels, that we are to look for the restoration of Anatomy. He was the real and true reformer, the bold and unflinching Luther in practical Anatomy, the untiring zealot in dissections, and the prompt and fearless exposer of error. Hence, he very soon brought himself into trouble, by daring to expose the numerous errors of Galen and others, of the existence of which his dissections at every step clearly convinced him. He published his Anatomy in 1543, and his descriptions of the bones and muscles are stated to be very minute, and not much surpassed even by modern au- thors. His figures are described as master-pieces of paint- ing. Vesalius attended Lectures in Paris, to which he had been invited by the Professors of the University. He devo- ted himself to dissections, by clandestinely procuring bodies for that purpose, and in the proportion that he discovered INTRODUCTION. 37 Galen's errors in Anatomy, in the same proportion did his veneration for that great man diminish, and this he did not fail openly to avow and publish. Immediately he had a host of enemies to encounter, and so hot was the opposi- tion, that he was obliged to leave Paris. His criticisms on Galen were published when he was only 28 years of age, in consequence of which daring and impious opposition, as it was supposed, to the infallible Galen, all Europe seemed in arms against Yesalius. And what was most trying, his Preceptor, Sylvius , at Paris, was the most bitter among his opponents. Sylvius changed the name of Yesalius to that of Vesanu§ or madman. In defiance of all opposition, however, his reputation increased, and he was appointed Professor of Anatomy in the University of Padua, by the Eepublic of Venice, which chair he filled for seven years. He was also first Physician to the Emperor, Charles Y, who kept him constantly at court. Vesalius' work, "De structura corporis Humani" is said to have been published when he was but about 25 years of age. In 1561,, Gabriel Fallopius, a pupil of Vesalius, distinguished himself. He was Professor of Anatomy in the University of Padua, and also author of an anatomical treatise under the title of " Observations Anatomicce" It was intended more as a supplement to the work of Vesalius, many of whose descriptions he corrects, which Vesalius it seems did not much like, and in consequence replied to his pupil. In 1563, Bartliolomcms Eustachius published at Venice a work called " Opuscula Anatomicce" which is highly spoken of. He is distinguished for his Anatomical pursuits and discoveries. The Ifah century opens with the brilliant discovery of the circulation of the blood, by Dr. Wm. Harvey, in 1628. The previous discoveries of Fabricius on the valves in the veins — and those of Servitus, Columbus and Caesalpinus, on the circulation through the lungs, were very important links to Harvey in making his immortal discovery. He met with 38 INTRODUCTION. much, opposition at the time, hut lived to see his doctrine universally embraced. In 1642, Wirtsungius discovered the pancreatic duct. Aselius, an Italian, discovered the lacteals, which Pecquet in 1651 traced to the thoracic duct, and on to the suhclavian vein. In this same year Thos. Bartholine has the credit of discovering the lymphatic vessels — though a Swede by the name of Olaus Rudbeck, and Jolivius an Eng- lishman, both put in their claims for priority of discovery. In 1660, Marcellus MalpJiigius became eminent for the accuracy of his descriptions, and for his discoveries of new structures. About this period, Johannes Swammerdam made some Anatomical publications, and was particularly celebrated for his manner of preserving different portions of bodies by injecting their vessels. In 1665, Frederic Ruysch, the great Dutch Anatomist, made his first Anatomical publication, which he continued for a period of 65 years, being universally celebrated for his minute injections, and for preserving every part of the body in its natural color, and with all its original freshness and beauty. In 1683, Gothofridus Bidloiv, Professor of. Anatomy at Leyden, published his "AnatomiacorporisHumani" where- in it is said the several parts are represented in plates as large as life. The plates are supposed to be those of Swam- merdam, which had never before been made public. Shortly after this, Diembroeck, Professor of Anatomy at Utrecht, prepared a work which became the standard work among students. Antonius Leuwenhoeck about this time also distinguished himself by the use of the microscope. The names of Albinus, Winslow, and Cheselden, with many others, are all famous in this century for their ana- tomical knowledge. The 18th century presents the brilliant names of Bichatj the father of General Anatomy, Morgagni, Scarpa, Soemmer- mg, the Monros, the Hunters, and a host of others. INTRODUCTION. 39 The 19th century is no less remarkable for its onward march and progressive improvement in Anatomy. Every nation seems to be vying with every other in that most honorable and useful of all species of rivalries, a more com- plete— yea, the most perfect knowledge of the structure of the body possible — with the view of more fully preserving health and prolonging life ; and the kind of Anatomical dis- covery and improvement which characterizes the present period, may be designated by the term Microscopic Anatomy. In this department figure the names of Schwann, Muller, Andral, Magendie, Carpenter, Nasmyth, Goodsir — and in our own country, the names of Wistar, Godman, Homer and Leidy, may be mentioned — the two former being more par- ticularly distinguished for their observations in the ordi- nary mode of dissections, while the latter have directed special attention to microscopic Anatomy. Numerous oth- ers equally eminent and indefatigable in our own and every other country, might be mentioned, who are now un- ceasingly engaged both in microscopic, and all other species of Anatomical analysis and research, which can by any pos- sibility shed a more perfect light and thorough knowledge upon the wonderful minuteness, complexity, and harmony in the structure of the human frame. Every portion of the body, whether solid or fluid, is being subjected to the magnifying power of the microscope, and the most interesting discoveries are being made in each. The various fluids, comprising the blood, chyme, chyle, and the different secretions and excretions, have all been subjected to this mode of examination, and the globules whose shape and appearance, with other characteristic properties of the fluids, were hitherto doubtful and disputed, are now settled with precision and accuracy. The cell of Schwann, and epithelia, which are likewise found to be cells, are now known after this method, to exist upon all free membranes, mucous and serous, as well as cuticular. All these details of modern discoveries are, however, 40 INTRODUCTION. noticed in their appropriate places throughout the present work, so that it is unnecessary to make further remarks in this place, or pursue the history of Anatomy in any greater detail at present. RULES FOR DISSECTION IN GENERAL. 1. Let each student supply himself with an apron, made either of glazed muslin or gum elastic, furnished with sleeves, and reaching from the neck to the ankles. 2. He should provide himself with a dissecting case, in which he should see that there are also two or more crooked needles, for sewing up the parts after dissection. He should also have a sponge, as cleanliness is of the utmost import- ance to neatness of dissection. 3. No more integument should he turned down than is necessary to fairly expose the part or parts under exam- ination, as the dissection is liable soon to become dry or putrefy — hence it is always necessary to replace the skin, or cover the parts with a cloth of several thicknesses, dipped in water, after dissection. 4. The knife should not only be sharp, but be in the best order possible, and always be kept so; for we are convinced, from much observation, that most of the failures, to the making a neat and satisfactory dissection, arise from hav- ing dull knives, and the consequence is disappointment and ultimate dislike, if not disgust, for any dissection whatever — hence we .would urge each student to furnish himself with a "razor-strop and Arkansas stone. 5. Hold the knife as you would a writing pen, and with the other hand keep the skin tense. We say with the other hand, for the fingers are always to be preferred, when you can use them, to the forceps. The skin is made tense, or put on the stretch, so that the cellular tissue be- INTRODUCTION. 41 neath it, and covering the muscle, shall likewise he put on the stretch — then, with a light and steady stroke of the knife, cut in the direction of the muscular fihres, and close to them, so as to he sure that all cellular tissue is removed, and the muscle thus fairly exposed. Indeed, if the student will simply recollect to keep his knives in first-rate order, hold the integument tense, and always cut in the course of and close to the fihres of the muscle, he cannot fail to make a neat dissection. ORGANIZATION. The structure and functions of the organs belonging to living beings constitute the science of organization. The vegetable and animal creation compose its two great divisions. It is the animal organization which claims our attention. An organ is regarded to be any portion of a living body capable of performing a complete act or operation, and this act of the organ is styled its function — thus the eye is the organ of sight— the ear, the organ of sound and hearing, &c. A number of organs, of different kinds, conspiring to one end, or to bring about one result, constitute an apparatus, as the apparatus of digestion, the lachrymal apparatus, &c. Organs of the same kind form a system, as the muscular, osseous and nervous systems — and The organs collectively have been styled the organism. A variety of definitions have been given as to the essen- tial nature of organization. One physiologist defines it to be the "process by which an organized being is formed, and organism the result of such process." By another, organization is made to consist in a "pecu- liar form and structure, containing liquids of the same nature as itself." 42 INTRODUCTION. By others organization is considered as the result of life; while some again view life as the result of organiza- tion, each alternately being made cause and effect. The celebrated Bichat describes life to be "the sum of the functions by which death is resisted." Another physiologist makes life to consist in "the phe- nomena peculiar to organized bodies, taken as a whole." M. Beclard asserts that life consists essentially in one fact, "that all organized bodies, during a determined pe- riod, are centres penetrated by foreign substances, which they appropriate to themselves, and from which issue others that become foreign to them; and in this movement of momentary formation the matter of the body changes con- tinually, but its form still remains." He adds, that life does not consist in a re-union of molecules, which were before separated, as occurs in the case of chemical attraction, nor simply in an expulsion of the elements previously com- bined, as in that which is produced by the expulsive action of caloric, but in a movement of temporary formation, in which some elements remain united, which would separate should life cease, and in which the elementary parts are separated without the action of caloric, and this vital ac- tion exists only in organized bodies ; and it is in this "close and reciprocal connection of organization and life that is to be found the reason why they have by turns been considered the cause and effect of each other." M. Beclard very justly remarks that organization and life are a complex idea — are inseparable in their connec- tion, and that life is "organization in action." Without entering into the abstract question of what is life? — a very unprofitable and, we think, useless specula- tion— we will at once proceed to consider the fundamental elements of organization, whose analysis is its only correct definition. The first element we notice as fundamental and essential to organization, is that the organized body shall have a definite living origin; that it shall be born of a parent like INTRODUCTION. 43 itself— grow, attain maturity, decay and die, after the manner of the heing it represents. Inorganic bodies, or those destitute of life, on the con- trary, are not horn, hut simply owe their origin to what are termed the "general forces of matter." They do not grow, hut owe their increase to accident, which occurs whenever particles, for which there is an affinity, come within the sphere of their attraction. Neither do they attain maturity, decay, or die, as they are destitute both of a living birth and growth. The second fundamental element of organization is a special and definite form. This we see every where throughout the vegetable and animal kingdoms. Every plant and flower — every tree and fruit — every animal — every genus and species, each after its own kind, has this special and determinate form, by which it is readily distinguished from every other form. Inorganic bodies, on the other hand, have no fixed and determinate form. The third element is a definite size. This is equally true, as of the form, in all the individual genera and species, both vegetable and animal. We see them all to have a special and determinate size, and though there may be occasional dwarfs, these are but exceptions, which, instead of overthrowing, rather confirm the general law. Inorganic bodies, it is well known, have no fixed size, but may be large or small, and constantly changing, just as accident makes them. The fourth element essential to organization is a definite and peculiar structure, or a regular and determinate ar- rangement of fibres, forming cells or areolae, and consti- tuting the cellular, areolar or spongy tissue. This peculiar structure, which does not belong to the inorganic body, constitutes the principal basis of all or- ganization; it is viewed as the primitive, original and 44 INTRODUCTION. forming part, entering into the whole organization, and constituting its most extensive and universal elementary solid. The fifth element is the nutritive fluid. This, called the sap in the vegetable, is the white or red blood in the animal. The relative proportion of this fluid varies in the two kingdoms; it is greater in the animal than in the vegeta- ble, and greater in youth than in old age. The sixth element is nutrition. This belongs to the whole organic world — from the blade of grass to the towering oak — or from the simple worm to the huge elephant — the forms of nutrition infinitely vary- ing, but the result the same in all, to wit, the appropria- tion of material for organization and its preservation. It is -upon this universal function that the growth of all organic bodies depends — the material of supply being from within the body. Now nothing like nutrition is seen in the inorganic be- ing, for when it grows it is not from within itself, and by a complicated process of action as occurs in the organic body, but simply by the addition of particle to particle of similar nature from without, and upon its superficies. A seventh element is the complete dependency of all the parts composing every organic body, and this is most es- pecially true of those which are high in the scale of animal formation. For here it is certain death to any part to be separated from the body of which it forms a portion, while the body itself suffers, in turn, in proportion to the importance of the part it has lost, and if it be any of the essential organs of life, death is as instant to the whole body as to these parts. It is true some animals, very low in the scale, as the polypus, may be separated into pieces, and each piece not only has the power to live, but still further to recreate itself into a perfect animal. INTRODUCTION. 45 In this case each fragment seems to possess all the parts of the whole animal, each having the generative and nu- tritive power perfect; there then seems to be no necessity that any of these parts should die. But let a section be made in what is called the eye or germ of these animals, and death is as certain as in the higher order; for here the chain of dependency among the several parts, making each fragment, as it were, complete in itself, is broken, and this essential element to organic existence as certainly destroyed. In the inorganic body we observe no such dependency among its several parts. Each can preserve its existence as well when separated from all the other parts and from the whole body as when united. The eighth element of organization is a limited duration. Death is the eternal fiat stamped upon all living, or- ganic bodies — they carry on their functions for a definite period of existence only, during the active and early exer- cise of which, the body grows, attains maturity, and then begins to languish, decay and die. Inorganic bodies, on the other hand, have no fixed pe- riod of duration — their existence can be terminated at any moment, either by mechanical violence breaking down their several parts, or by the play of chemical affinity destroy- ing their nature, or if none of these circumstances operate, their duration may be unlimited. These are the different elements which are regarded as the most essential in forming organization. We now proceed to notice the principal of those most es- sential in preserving organization — which consist of, 1. Atmospheric air. 3. Water. 2. Food. 4. Heat. These elements are the vital stimuli, whose presence is indispensable to the existence of all kinds of organization, whether animal or vegetable. In the higher order of animals, the necessity of breath- 46 INTRODUCTION. ing, taking food and drink, and having a proper tempera- ture, is plainly manifest. Though there are some, it is true, which have the power of apparently suspending their functions for a while and entering into a torpid state — and consequently, remaining in a great measure without the influence of the vital stim- uli; they nevertheless exist, and again revive in their former activity. This, however, by no means subverts the general law of the necessity of the presence of the vital stimuli to organic existence — for atmospheric air and a certain amount of tem- perature is present in sufficient quantity to account for the remaining vitality which is found to have been present, and again to revive on the re-application of the balance of the vital stimuli. Now, between these two series of elements — the one for forming and the other for preserving organization, nature has established the most intimate relations — relations close, fixed and determinate — constituting so many laws which are essential to be obeyed for preserving the integrity of organization. These relations or laws consist essentially in the nice adaptation of the one class of these elements to the other, when in their natural state of integrity. Examples of violation of these relations are seen when carbonic acid gas, sulphuretted hydrogen, or any other nox- ious gas is taken for atmospheric air, or when putrid food and alcohol are taken in the place of bread and water. The result of these violations, in destroying organiza- tion, health and life, is familiar to all, and therefore it is unnecessary to enter into any detail. INTRODUCTION. 47 VARIETIES OF ANIMAL ORGANIZATION. Nature it seems has constructed the animal kingdom upon four great models or types. 1. The Kadiata — forming the zoophytes. 2. The Articulata — worms, insects, &c. 3. The Mollusca — shell-fish, &c. 4. The Vertehrata — having a spine. The Eadiata, so called from their resemblance to a ra- diated flower or star, are of simple structure, and described as having no distinct nervous system, TIO organs of sense, no heart, and having white blood. This class includes the polypus, hydratid, coral, sponge, star-fish, infusoria, &c. The Articulata are a step higher in organization, for here are found nervous ganglia, forming a longitudinal chain along the median line of the body. The body itself is di- vided into rings, which feature gives the name to the Class, and has a protection or kind of skeleton exteriorly of hard- ened skin, or horny covering, as seen in the insect and lob- ster. The blood is also generally white, and there is no heart, but simply a vessel running along the back called the dorsal vessel. There are senses, but they are more or less incomplete. This Class includes the Crustacea, as the Crab, &c., the Arachnides or Spiders, the Annelides or Worms, and In- sects. The Mollusca, as their name implies, have the body soft, and like the Articulata, have nervous ganglia ; but, instead of being united, these are found scattered throughout the body, and not in a chain along the middle line. The senses are also incomplete, the blood, white; but here we find a heart. There are no rings, no external skeleton, but simply a stony crust or covering constituting the shell. 48 INTRODUCTION. The Snail, Oyster, Nautilus, &c., are specimens of this Class. The Vertebrata form the next and highest step in the animal kingdom. This Class, deriving its name from all its members having vertebras or a spine, is principally characterized by the body being symmetrical, the nervous system being composed of a brain and spinal marrow, as well as nervous ganglia, by the blood being red and warm, and there being a heart and five senses. These four divisions, constituting the four great varieties of animal organization, have each many subdivisions into the different orders, genera and species. Each of these varieties, with its various subdivisions, as already stated in reference to organization in general, owes its existence and preservation entirely to the fixed relation established between its peculiar structure and one or more of the fundamental elements of preservation. We shall take the division of the vertebrata by way of illustration. The vertebrated Class has four principal branches — Fishes, Keptiles, Birds, and Mammalia. Now the organization of Fishes is constructed with special reference to the element, water — the whole exterior and interior form, as the fins, gills, air-bladder, &c., all clearly show that water is their natural element — and that not- withstanding they require air and food, and have more or less relation with these principles, yet the great and prom- inent relation is with water, without which the whole variety would soon cease to live, though there might be free supply of both air and food. Eeptiles have a modification of structure which adapts them to both water and air, in each of which some of them alternately live, as in the cases of the turtle, crocodile, frog, &c. Birds being made for flight, have their special relations with the atmosphere. This is their essential and peculiar INTRODUCTION. 49 element, as their whole organization shows. For we find the exterior of the body covered with feathers— the remark- ahle property of which is lightness — nicely adapted for sustaining them in the air. The lungs occupy the abdom- inal as well as thoracic cavity, there being no diaphragm, and thus, extending the almost entire length of the trunk, form as it were so many bladders, which being filled with air, give the body the same specific gravity with this fluid — consequently placing the animal in the most perfect rela- tion for moving and living in this element. The skele- ton likewise receives air, thus rendering the body still lighter — and so with every other part, each being adapted the one to the other, and the whole specially to the atmos- phere, the fundamental element of this variety of organi- zation— for a bird can no more live under water, than a fish can in the air. The class mammalia, divided into the carnivorous and herbivorous animals, have organizations formed with spe- cial reference to food — the one of these living on flesh — the other on grass, fruits and grain, and the structure in each, as most distinctly seen in that of the teeth, stomach and alimentary tubes, corresponds to the particular kind of food on which they respectively subsist — and so fixed is this relation between the kind of food and the organization adapted to it, that to change the food of the one class for that of the other, would be death to both. The same may be said in reference to climate. The polar bear could no more live under the equator, than the ourang- outang could under the north pole — each having its organ- ization made with special reference to temperature. Now, in all these instances we find the variety of or- ganization depends upon fixed relations — established more particularly with one of the fundamental elements than another — which particular relationship constitutes so many special laws for each variety — violation of which in each case is destructive to organization, and that just in propor- tion to the offence. But these special laws by no means 4 50 INTRODUCTION. conflict with or exempt from the operation of the general laws to which all organization is subject. The last example of variety we have to offer, is the organization of man. Man, it is well known, stands at the top of the animal scale — forms the highest and most perfect link — is the most complex and varied — has the most extensive and multi- plied relations, and the greatest number of properties and powers. And as organization differs and becomes complex in proportion to the number and variety of its properties and relations, we find in man's formation a miniature rep- resentation of all we see in the inferior animal world — with the addition of his own distinguishing and surpassing structure, adapted to his intellectual and moral powers. CONSTITUENTS OF HUMAN ORGANIZATION. Analysis resolves the constituents of human organization into, 1. Chemical. 2. Organic elements. The chemical consist of oxygen, hydrogen, carbon, nitro- gen, sulphur, phosphorus, chlorine, fluorine, potassium, aluminum, calcium, sodium, magnesium, silicium, iron, manganese, to which some have added titanium, lead, copper, iodine and bromine. Of these, nitrogen and oxygen are found in a simple, pure state — both in the blood, and nitrogen in the intesti- nal gases. The rest exist as binary, ternary, or quartenary com- pounds. The binary are inorganic compounds, and con- sist of, 1. Water, composing the largest portion of the fluids of the body, entering into the solids and producing the differ- ent degrees of softness. 2. Carbonic acid, found in the blood, exhaled from the lungs, skin, urine — as well as united with lime, potash, INTRODUCTION. 51 soda, forming the carbonate of lime in the teeth, bones, cartilage, &c. Carbonate of potass a in the serum. Carbonate of soda in the serum, hile, saliva, tears, sweat, mucus, teeth, hone, cartilage, &c. There are also carbonates of ammonia in the urine, and of magnesia in the grease of the skin. 3. The union of phosphoric acid with lime, soda, ammo- nia, &c., as, for example, the phosphate of lime composing by far the greater bulk of the bones, and also existing in the teeth, cartilages, and pineal gland. The phosphates of soda and ammonia are seen in the urine, the blood, saliva, tears, &c. 4. The compounds of Chlorine, as those with hydrogen sodium, potassium, ammonium, and calcium, forming chlo- rides of these bodies, are seen in the gastric juice, blood, brain, muscle, bone, cartilage, dentine, pigment, milk, saliva, sweat, &c. 5. Sulphates -of potash, soda and lime, are seen in the cartilage, gastric juice, urine, bile, sweat, hair, cuticle, saliva. And other binary compounds are also discovered to exist, as the fluoride of calcium and alumina, in enamel of the teeth, silica and oxide of manganese in the hair, oxide of iron, in hematine and black pigment, oxide of titanium, and sulpho-cyanide of potassium in the saliva. The ternary and quarternary compounds include the Organic Elements, whose distinguishing feature is, that they are only found in living bodies, whether animal or vegetable, and that the most prominent of them possess an additional element, not found in the inorganic, which is nitrogen, upon whose presence depends the rapidity with which some structures become putrid, or pass into decom- position. This remark refers more particularly to the ani- mal compounds — the vegetable products, with very few exceptions, are deficient in nitrogen. The Organic Elements having nitrogen are, 52 INTRODUCTION. 1. Protein, 6. Globulin, 2. Albumen, 7. Spermatin, 3. Fibrin, 8. Mucus, 4. Casein, 9. Lachrymal matter, 41 5. Pepsin, 10. Keratin. Protein is regarded as the basis of all the other elements, is found in every animal, and it is said that no tissue or organ is destitute of its presence. It can be obtained by boiling albumen in a weak so- lution of caustic potass, and then precipitating with an acid. The gluten of wheat-flour, after the starch is washed away, and treated in the same manner, also yields protein. Thus obtained, in the moist state it is gelatinous, without smell or taste, insoluble in water, ether or alcohol, but soluble in dilute acid. When dry, it is hard, brown, and brittle. According to Mulder, its discoverer, it is chemically composed in atomic weights, of carbon 40, hydrogen 31, nitrogen 5, oxygen 12. Albumen is found in the serum of the blood, lymph, chyle, &nd a beautiful specimen is seen in the white of the egg. It is one of the special elements of the brain, and exists also in pus, and many of the secretions. It is yellow and .brittle when dry, coagulates by heat, creosote, spirits of wine, and some acids; is soluble in water, and forms an insoluble compound with corrosive sublimate, sugar of lead, alum, nitric and tannic acids. It is composed, according to Gay Lussac and Thenard, of Nitrogen, 15.705, Carbon, 52.883, Hydrogen, *7.540, Oxygen, 23.8*72, in an hundred parts. Fibrine constitutes the basis of the muscular system, exists in the blood, chyle, lymph, and in abundance upon INTRODUCTION. 53 inflamed surfaces, is soluble in the blood, from which when drawn it readily coagulates. It can be obtained from the blood, by stirring it briskly with a rough stick, when it will appear in the form of fibres or threads. Vegetable acids, their salts, and caustic alkalies prevent coagulation. Its chemical elements are Nitrogen, 19.934, Carbon, 53.360, Hydrogen, V.021, Oxygen, 19.685, in the hundred parts. Casein exists most abundantly in milk, but is also found in the blood, saliva, bile, pancreatic fluid, lens, and else- where. In solution it is of a pale yellow, coagulates by heat, acids, alcohol, and rennet. It is soluble in water, and in this state has the consist- ence of mucilage. When dried it is of an amber color, and very friable. Cheese is composed of dried casein and butter. Accord- ing to Mulder its chemical elements are in one hundred parts — Nitrogen, 15.95, Hydrogen, 6.9T, Carbon, 55.10, Oxygen, 21.62. These four organic elements constitute the great proxi- mate principles of animal formation. And the albumen, fibrin, and casein, seem to be formed from the protein, or more properly speaking, only differ from it by having in addition a little sulphur and phos- phorus in combination. Protein, it has been stated, is always found in the albu- minous vegetables, and has the same constitution in them as in the animal frame. Hence, we can readily under- stand how and why it is, that vegetable matter is so read- ily converted into animal, and so important in sustaining life. 54 INTRODUCTION. The other elements not so extensively diffused, we will briefly notice. They are as follows : Pepsin was discovered by Schwann in the gastric juice, the parietes of the follicles and glands of the stomach, and may be obtained by macerating the stomach of an animal. "With an acid it readily dissolves albumen and fibrin — resembles very much albumen — and is considered the ac- tive agent in digestion, the prime element in converting the food into chyme. Chemical Analysis makes Pepsin consist of Oxygen 10, Hydrogen 32, Nitrogen 8, Carbon 48. Globulin exists in the envelopes of the blood corpuscles, and resembles albumen. Simon regards it as casein united with hgematin. Spermatin is found in the seminal fluid, and looked upon as probably only fibrin. Mucus is furnished by the mucous glands. It is insoluble in water, transparent when evaporated to dryness, is soluble in acids, does not coagulate by heat, is precipitated by tannin, and is always found united with the cast-off epithe- lium and pus. Lachrymal matter. This is found in the tears after evap- oration, and is regarded as insoluble mucus. Keratin is so named from being found in the nails, hair, and cuticle, though its character is not yet fully determined. EXTRACTIVE ELEMENTS. When protein and the salts are removed from animal matter, what is left is called Extractive matter. This is found pretty generally diffused through the body, but most abundant in muscle. The dried extract of flesh, if treated with water, diluted alcohol, or pure alcohol, forms either a water extract, spirit extract, or alcoholic extract. The spirit extract is termed ozmasome, (from o Clot Of these substances the serum contains the water, albu- men and salts, the analysis of which by the same chemist is in 1000 parts: Water, 906; Albumen, *78; Animal Matter, soluble in Water and Alcohol, 1.69; Albumen, combined with Soda, 2.10; Crystallizable Fatty Matter, 1.20; Oily Matter, 1; Hydrochlorate Soda and Potassa, 6; Sub. Carb., Phosphat. Sodae and Sulphat. Potassae, 2.10; Phosphate of Lime, Magnesia, 2 ; Iron, Sub. Carb. Lime, 2 ; Magnesia, 0.91; loss, 1. The Crassamentum contains the fibrin and coloring mat- ter. Fibrin, known by the names of coagulable lymph and fibre of the blood, is the basis of muscle, and, according to Berzelius, in 100 parts, has Carbon, 53.360; Oxygen, 19.666; Hydrogen, 7.021; Nitrogen, 19.934. The coloring matter contains iron, which is found in the red globules. MICROSCOPIC EXAMINATION OF THE BLOOD. FIG. 2. Under the microscope, nu- merous little red particles, termed globules, or corpus- cula, are observed. The form of the globules varies in different animals; in man and all the mammalia it is circular and flattened, with a cup-like depression on both surfaces, while in birds, reptiles and fishes the form is elliptical. FIGURE 2. b represents the blood corpuscle as seen within the focus of the microscope ; a shows it when beyond the focus. Magnified 400 diameters. 72 MICROSCOPIC EXAMINATION OF THE BLOOD. The size varies equally with the form. In amphibia they are regarded as the largest; in birds and fishes next in size, and in mammalia smallest. The human globules are about one-fourth the size of those of the frog. They are larger in the embryo than the adult, and are made to measure from the 1-5000 to the 1-3000 of an inch, though the size often varies. The globules or corpuscles of the frog show, under the microscope, that their structure con- sists of a membranous envelope — thin, transparent and vesicular — enclosing a nucleus, seemingly solid, and having the colored matter surrounding this nucleus and placed between it and the envelope. The nucleus is regarded as about one-third of the length of the corpuscle. The envel- ope is found to be highly elastic, and both it and the col- oring matter are considered to be quite soft and yielding in their nature. The structure of the human globule is believed by some to have a similar envelope, nucleus and coloring substance, as in the frog, though others consider it extremely ques- tionable whether the blood corpuscle in man, or any of the mammalia, have any nucleus at all, and are therefore dis- posed to deny its existence in these animals. The nucleus is generally seen in the centre of the corpuscle. Besides the red corpuscle, there is another kind called the pale or color- less corpuscle. These are found to be fewer in number, larger, and to vary less in size and shape than the red. As their name implies, they are destitute of color and specifi- cally lighter than the red. The globules are suspended in the liquor sanguinis, their natural fluid, without alteration. Water dissolves the col- oring matter, leaving the nucleus; acetic acid changes the form as well as dissolves the coloring matter; and liquor potassse dissolves both coloring matter and nucleus. Thus the blood is seen to consist of many chemical and microscopical elements, each and all of which are adapted the one to the other, in precise and definite proportions, to constitute health ; and to add to, abstract from or alter in any way the natural relation between any two or more, VITAL PROPERTIES AND RELATIONS OF THE BLOOD. would be to produce disorder and disease, primarily in the blood itself, and secondarily in the organs. VITAL PROPERTIES AND RELATIONS OP THE BLOOD. Dr. John Hunter stands prominent in demonstrating the vitality of the blood. The analogy of the fresh egg furnished one of his strongest proofs, showing that vitality can be connected with the fluids where there is no visible organization present. The fresh egg may be exposed for weeks with impunity to a temperature that would certainly putrify the stale egg. The hen, whose period of incubation is three weeks, keeps her eggs at a temperature, it is said, of 105 degrees, yet when the chick is hatched the yolk is perfectly sweet. This remarkable power of resistance to heat in the fluid of the egg, could be attributed to nothing but its vitality. Its power of resisting cold is equally great. Mr. Hunter exposed an egg to 1*7° and 15° of Fahrenheit, and found it took half an hour to freeze it. When thawed and again exposed to a temperature of 25° it froze in one half the time. A fresh egg, and one previously frozen and again thawed, were placed in a cold mixture of 25° Fahrenheit: the egg that had been frozen was again frozen 25 minutes sooner than the fresh. Fresh drawn blood, and blood that had been frozen and then thawed, by similar experiments, showed the same re- sults— all leading to the same inference of the blood's vitality. Another proof of the blood's vitality, is its preserving the fluid state while circulating in the vessels; for, on be- ing removed from the body, coagulation, it is well known, very soon occurs. And it occurs, not because the blood is at rest and ceases to circulate, for experiment shows that if it be kept at the same temperature; and have the same rapidity in a dead tube as in the living, it will still become solid, proving that its fluidity in the body must be owing to vital agency. 74 VITAL PROPERTIES AND RELATIONS OF THE BLOOD. Coagulation of the blood itself has been brought forward as a proof of its vitality; for from the experiments of Hunter and Magendie, neither cold nor heat, rest nor motion, nor any other known agency, seems to prevent the blood from coagulating. This process is therefore regarded as vital. The Automatic motion, observed among the blood corpus- cles, is thought to be further proof of the blood's vitality. This motion, however, by others is considered a delusion. The last proof we shall here present of the blood's vitality, is its vivifying influence on the whole body, which point illustrates its vital relations. There is no part of the body where the blood does not circulate, and in which it is not distributed ; hence every portion must be directly related with it. And so close is this relation and dependency, that if, by ligature, ampu- tation, or any other cause, the blood be prevented from reaching any organ or part, that organ or part will inevi- tably die. But allow the blood to circulate in and through it, and it becomes refreshed, and exhibits again all the sensible proofs of vitality. Hence the necessary inference, that vitality must be con- nected with the blood — that this vitality is conveyed in the round of the circulation to every portion of the body — and further, that all the solids themselves owe the existence and continuance of their own vitality to the supply of this fluid. The Formation of the Blood is the last point we propose to notice: The Chyle and Lymph are the great sources from whence the materials for the formation of blood are derived. The Chyle, formed from our food and drinks by the process of digestion, and found in the upper part of the small intes- tine, is taken from thence by the Lacteals, and, through the thoracic duct, conveyed into the circulation, and thence on to the Lungs, where its formation into blood is finally effected. Organs are regarded as the special instruments or means for the formation of blood in the higher order of animals. THE CELLULAR TISSUE. As, for instance, the Lungs give the blood its color — here elements are thrown off and others received. The digestive tube, as already mentioned, performs the initiatory steps in its formation — and the organs of excretion are so many purificators in the process. But we have blood formed where there is no organ or set of organs to account for it — as in the egg. All we see is the germinal membrane, which has the power of assimila- ting the fluids of the egg to itself, and converting them both into blood and organized vessels. "This fact," says Professor Muller, "teaches us that we must not expect to discover the process of the formation of the blood and red particles in any special organ of the adult." "Indeed," he continues, "it is very probable that in the adult the chyle is converted into blood under the same general vital conditions which are in action in the incubated egg." From this it would seem that nature has not assigned the formation of the blood solely to any par- ticular part or organ of the body. But, in the language of Dr. Stevens, "when more agents than one are concerned. in the production of certain effects, we ought not to con- sider any one link in the chain as the sole cause, for all the animal functions act in a circle, and are mutually dependent upon each other." CHAPTER III. THE CELLULAR TISSUE. ANALYSIS. STRUCTURE, EXTENT, FORM, QUANTITY, CONSISTENCY, CONTINUITY — EXTERNAL AND INTERNAL CELLULAR TISSUE RELATIONS, USES, DEVELOPMENT. CELLULAR Tissue (called also Areolar and uniting Tissue) consists of filaments of white, soft layers, intermixed and interwoven in different ways, so as to form an arrangement THE CELLULAR TISSUE. of cells — hence the name Cellular — these cells are of varied size and shape, and all communicate. The most beautiful specimen of this tissue is seen in the anterior mediastinum after throwing back the sternum. Here the cells are very dis- tinct, though in other places they are so compact as to appear membranous. The extent of the cellular tissue is commensurate with that of the entire body and its various organs. It is found beneath the common integu- ments, as extensive as the skin itself, forming a general external layer, called the subcutaneous cellular tissue. It likewise surrounds every organ, and every part and fibre belonging to each organ. In a word, there is no part where it is not to be seen; and it may very properly be termed the matrix or soil in which germinate and expand all the other structures. Bordeu, in consequence of its peculiar connections, styles it a Cellular atmosphere. The/orm of this Tissue, as just stated, is Cellular, but in addition to this special form, it has another and more varied one, which it derives from its intimate relationship with the whole body and its different parts, so that if this Tis- sue could be separated entire from every part and organ, it would present a perfect outline of the whole system. It would then be seen to form a series of moulds or chambers, each varying in size, and adapting itself to the organ to be accommodated. Around the fasciculi of muscle, it takes the form of little tubes, as numerous as the muscular fibres themselves — con- nected with hollow organs, it puts on the form of a mem- FIG. 3. a Arrangement of fibres in Areolar Tissue— magnified 135 diameters. b Cells being developed into Cellular Tissue. THE CELLULAR TISSUE. branous cavity — and around glands and their granules, it is more or less round. The quantity of this tissue varies according to its situation in the body, and the period of life in which it is examined. In the cranium and spinal cavity, there is very little; on the surface of the head and face and in the orbits, there is more; about the trunk, both externally and internally, it is abundant, and particularly in the mediastinum, within the thorax, around the kidneys and rectum, and within the abdomen and pelvis. In the extremities it is also abundant, particularly in the axilla and groin. The quantity seems to be regulated as a general rule, ac- cording to the motion of the part — the greater the motion, the more of this tissue is present; the kidneys, rectum and some other parts, it is true, are exceptions. The quantity in infancy is greater than in the adult — it is also more abundant in women than in men — and in the lymphatic than in the bilious temperament. The consistency equally varies with the quantity — but the firmness is not found in a ratio with the quantity — as in the mediastinum and around the kidneys, where it exists in large quantities, it is exceedingly fine, delicate, easily torn, and having but a slight degree of consistence; whereas, in the fascia lata of the thigh, the palmar and plantar fascia of the hand and foot, it presents an extraordinary firmness and degree of strength. The continuity of the cellular tissue can be traced through- out the body. The foramina of the cranium are the means of communication between the internal and external por- tions of the head and face — from the face it is continued down the neck upon the external surface of the chest — then through the upper opening in the thorax, it enters this cavi- ty, covering its different viscera; from this it descends along the oesophagus and through the openings in the diaphragm, into the abdomen and pelvis, from whence it is traced under the crural arch and foramina of the pelvis, continuous with that belonging to the extremities. It has been divided into the external and internal cellu- 8 THE CELLULAR TISSUE. lar tissue, the former giving the general covering to the body, surrounding, separating and connecting its different parts, while the latter enters into and forms an essential part of their structure. The relations of the cellular tissue are of two kinds — the one with organs, one of whose surfaces is free, as the skin, serous and mucous structures, and the other with organs where the attachment is all around. The adhesion of this tissue varies in different parts. Be- neath the hairy scalp, it is with difficulty separated from the aponeurosis and muscles below — and along the middle line of the body, as upon the nose, the lips, linea-alba, and spinous processes, it is considered more adherent than at any other points — while in the face, trunk and extremities it is quite free and loose. The cellular tissue allows, by its properties of elasticity and flexibility, the movements of the several parts to be per- formed readily, the one upon the other — which properties themselves are preseryed by the presence of the serum within its substance. In addition to its mobility, this tissue has other uses. The mucous membrane, as that of the stomach, intestines and bladder, connects with the muscular fibres that sur- round it — and in the serous membranes it permits that expansion and easy motion we observe in many of the viscera. The organic element of cellular tissue, is mostly gelatin. Its development, from microscopic observations, commences with the nucleated cell, which becomes transformed and elongated into fibres, and finally into a fasciculus of ex- tremely delicate fibres. It is readily regenerated when destroyed. FIG. 4. ADISPOSE TISSUE. 7» ADIPOSE TISSUE. The fat was formerly supposed to be a secretion from the cellula*r tis- sue, and that its cells were the places of deposit. The opinion of Hunter and Beclard, that there was a dis- tinct apparatus for this secretion, the microscope now proves to be correct. It reveals the vesicles or cells (fig. 4) entirely distinct from those of the cellular tissue, in having no com- munication, and by retaining the fat in their sac-like shape, so as to com- pletely prevent its changing its place, as is the case in the fluids of the cellular tissue. The fat cells are found scattered at wide intervals, in the cellular tissue, and also collected in clusters at different points in this same structure. Indeed they are almost commensurate with the cellular tissue, if we except the interior of the cranium, the ball of the eye, the ear, the nose, the penis, the eyelids, and the substance of glands, where they are wanting. The parietes of the fat vesicle are very delicate and sur- rounded with blood vessels, forming a net work, from which is secreted the fat deposited in the cell. The fat exhibits striking differences at different periods of life. In the foetus and infancy, it is more liquid and transparent than in the adult, when we find it more firm and of a yellowish color. Its quantity, as regards position, is just the reverse in certain organs in youth and adult age. The skin of the infant abounds with fat, causing the roundness and plumpness so constant at this period — while observations show there is very little about the heart, kidneys, omentum, rectum, and other internal parts. , FIG. 4. Exhibits the cells of adipose tissue— magnified 135 diameters. 80 THE SEROUS TISSUE. In the adult, on the contrary, the fat lessens in quantity and in many instances entirely disappears from beneath the skin — while it collects in large quantities about the heart, kidneys, omentum, &c. The uses of the fat vary with its situation. Beneath the skin, it covers the projections of bones, thereby increasing the rotundity and adding beauty to the form. In the or- bits it serves as an elastic cushion for the eye to roll upon. In the palms of the hands and soles of the feet, it prevents injury to the skin from pressure — and in being a bad con- ductor of caloric, it assists in preserving the body of uniform temperature, while in nutrition, it is regarded as the great store-house of supply, during the wasting process of pro- tracted disease. THE SEROUS TISSUE. ANALYSIS. IDENTITY WITH CELLULAR TISSUE, FORM, DIVISIONS, REFLECTIONS, STRUCTURE, FUNCTIONS. The serous tissue has been brought under the same head with the cellular, being regarded by the highest authorities as a -modification of the same. The inflation of the subjacent cellular texture with air, reduces the serous membrane to the same form — protracted maceration has the same effect with greater certainty : when the cellular tissue is inflated, the parietes of the cell strongly resemble the finest parts of the serous tissue — as seen in the arachnoid membrane. There is a further identity of functions and affections — exhalation and absorption being performed in each, and dropsy passing, it is said, readily from the one to the other. The form of the serous tissue is that of a shut sack. It is divided into — 1st. The serous tissue proper, as the peritoneum, plura, tunica arachnoids, and tunica, vaginalis, situated in the abdomen, thorax, cranium, and upon the testicle. THE SEROUS TISSUE. 81 2d. The synovial membranes. 3d. The bursae mucosae. The form of the serous tissue has been stated to be that of shut sacs — this is true of all except the peritoneum of the female, which is open at the extremity of the fallopian tubes. These sacs all line the various cavities in which they are found, and are thence reflected upon the various organs and viscera. These reflections have different names, ac- cording to their situation, uses, attachments, &c., as the omentum gastro-hepaticum or minus, omentum gastro- colicum or majus, gastro-splenicum, mesentery, meso-colon, meso-rectum, the ligaments of the liver, the broad liga- ments of the uterus, the ligaments of the bladder, &c., all of which are the names of so many reflections of perito- neum, illustrating its position and connection with the stomach, liver, intestines and other organs. The serous tissue, with some few exceptions, forms a complete investment to all the organs and parietes of cavities with which it is connected ; that portion surrounding the walls is the. parietal, that covering the several organs is the visceral layer. Its continuity as one unbroken mem- brane, except the female peritoneum, is admitted by all anatomists, and it is said to have been successfully dis- sected, entire and complete, without the slightest rupture, from the abdominal cavity and its various organs, by one Nicholas Massa. How the peritoneum, pleura, &c., shall cover the several viscera, and yet these same viscera be upon the outside of its cavity, is often a difficulty with the young beginner in anatomy. The comparison with the double night-cap, is used as an easy and familiar illustration. That part of the cap which covers and fits close to the head, represents the peritoneum covering the different organs, while the por- tion that floats loose above the head, and is external, repre- sents the peritoneum lining the interior abdominal walls. Now it is plain that the head, though covered by the cap, is not in its proper cavity, but on the outside. And so with the peritoneal sac, all the organs are upon the outside, and 6 82 THE SEROUS TISSUE. obtain a covering by protruding into or pushing this membrane before them into its cavity. The structure of the serous tissue consists of thin, white, transparent membranes, composed, according to Muller, of fibres, like the cellular tissue, collected into bundles, and forming a membrane. It has two surfaces, the one at- tached, the other free. The free surface is smooth, pol- ished, and constantly lubricated by an albuminous fluid, which thus allows the free motion of the several organs upon each other; and the microscope shows that this free surface is covered by an epithelium, formed of flattened scale-like cells, as the epidermis — polygonal or tesselated, and having each a nucleus in its centre. Some of these cells are seen to elongate into hair-like filaments called cilia, which are in constant vibration, and, as supposed, intended to prevent stagnation of the fluids with which they are in contact. The Synovia! Membranes are simply serous sacs of smaller size found about the different joints. They line the in- ternal surface of the capsular ligaments, and are thence reflected upon the cartilages covering the articular ends of the bones. They are also seen under the annular liga- ments, around tendons and beneath fasciae. The synovial fluid differs from the serous in being more viscid. The Bursce Mucosce forms the third division of the serous system, and are also modifications of the cellular tissue. They consist of serous sacs, most generally placed between muscles and tendons and bones, and in connection with articular cavities and ligaments. They secrete a fluid for lubricating the parts with which they are in contact. Mr. Hooper enumerates the following: The head has 4; the shoulder joint 11; elbow joint 4; wrist and hands 15; hip joint 12; knee joint 6; the foot 10 — making 62 bur- see mucosse to the whole body, besides others more irregular in their distribution. The functions of the serous tissue are those of secre- tion, exhalation, and absorption. The fluid secreted is designed to allow free and easy motion among the several THE VASCULAR TISSUE. 83 viscera, between the tendons and bones, and at the several joints. Morbid accumulations of this fluid constitute sev- eral varieties of dropsy — as ascites in the peritoneum, hydrothorax in the pleura, hydrocele in the tunica vaginis testis, &c, A variety of opinions have been entertained as to the uses of the different peritoneal reflections, particularly the omentum majus. But as they are mostly fanciful, we will only mention one, which seems to be the most rational explanation, and that is, that they allow of the free ex- pansion of the organs with which they are connected — as the omentum majus, during the reception of food, permits the safe enlargement of the stomach, and the broad liga- ments, during gestation, that of the uterus. The sensibility of this tissue is remarkably obtuse in the healthy state, but when inflamed causes the most acute pain. CHAPTEK HI THE VASCULAR TISSUE. ANALYSIS. OBJECT, DEFINITION OP CIRCULATION, DIVISION, SITUATION, FORM, ANASTOMO- SES, DISTRIBUTION, RELATIONS, DEVELOPMENT. THE great object of the vascular tissue is to convey the nutritive fluid to every part of the body, to supply the ma- terials of its growth and renovation, as well as to remove those of its decomposition and waste. The performance of this duty is styled circulation, from the fact that the blood beginning at the heart and going to every portion of the system, and then back again to the heart, moves as it were in a circle; hence it is said to circulate; and the function itself, as just stated, is called the circulation. The heart, arteries and veins constitute the parts be- longing to the circulation proper — the first being the cen- 84 THE CAPILLARY TISSUE. tral organ for propelling the blood, the second conveying it to every part of the system, while the third returns it back again to the heart. Besides this general circulation, there is also distin- guished the pulmonary, the portal, the capillary and the lymphatic circulations. The vascular tissue belonging to each of these circula- tions will be examined in the order of their development, which physiology shows to be — 1. The Capillary. 2. The Portal. 3. The General. 4. The Pulmonary. 5. The Lymphatic, an appendage to the blood circulation. THE CAPILLARY TISSUE. FIG. 5. The capillary tissue (from capillus, a hair,) is situated between the arteries and the veins, at the termination of the one and the commencement of the other. FIG. 5 shows the capillaries between the termination of the arteries and the commencement of the veins in a frog's foot. Magnified three diameters, aa the veins ; 66 the arteries. THE CAPILLARY TISSUE. 85 The precise point of separation is not determined; hence this tissue is viewed as a system of vessels belonging neither to the arteries nor the veins, "but one sui-generis, and, ac- cording to Bichat, independent in its action. The microscope reveals the capillary tissue to consist of a multitude of very minute, hair-like vessels, having distinct parieties, and assuming the form of a net-work. Though this is the general form, there is found to be some variation from the different sizes of the meshes, and from their being elongated or not. The capillary arrangement in the small intestines, according to Soemmering, is arbor- escent; in the muscles a bunch of twigs; in the tongue a hair pencil; in the liver a star; in the schneiderian mem- brane a trellis-work; in the choroid plexus of the brain, and testicle, a lock of hair; in the kidneys glomerulate. The capillaries are the minutest tubes in the body, con- sisting, says Beclard, of thin, soft, transparent walls; and, according to Muller, having a mean diameter of 1.3700 to 1.1850 of an inch, allowing sufficient space for the free passage of the blood globules, which are only from the 1.5000 to the 1.3000 of an inch. The structure of the capillaries is regarded by Schwann as fibrous, the same as the larger vessels, and their con- tractile power experiments demonstrate to be far greater. The capillaries are not equally abundant in every por- tion of the body. The quantity is estimated by injections, congestions and inflammations. An opinion prevailed that the whole body was made up of blood-vessels, from the very minute injections of the celebrated Ruysch. The micro- scope, however, shows that various parts of the body are more vascular than others, and that there are some en- tirely destitute of any vessels whatever. The mesentery, or the web of the frog's foot under the microscope, pre- sents its most minute capillaries, those admitting but one globule, as separated by a considerable space, while in the mucous membrane, belonging to the organs of respiration, in the same animal, it has been observed to be impossible to stick a very fine needle without opening several of these 86 THE CAPILLARY TISSUE. vessels. The skin of man also shows that there is no point on its surface that can be pricked without drawing blood. The mucous membranes are as abundantly, if not more so, supplied with capillary vessels than the skin. The cartil- ages, epidermis and hair are not penetrated by injection, and show no blood-vessels whatever. The ligamentous structure, the dura-mater, periosteum, &c., have few blood- vessels. The question here arises, if these parts have few or no blood-vessels, how do they grow and how are they nour- ished? The answer to this question led Bichat to believe and assert that there was another kind of capillaries be- sides the sanguineous, which carried the serous or colorless portions of the blood to the white structures, and which he called exhalants. The existence of exhalant vessels has never been satisfactorily demonstrated, though admitted by many to exist. The lymphatic capillaries come under the same head, both of them being considered equally ne- cessary for development and support to the white organs, as the sanguineous capillaries are to all other parts. Various agents are capable of acting on the capillaries, producing contraction and dilatation, and these may be mechanical, chemical or mental. The principal functions of the capillaries are those of nutrition and secretion, and their independent action, ac- cording to Bichat, that of carrying on their own circula- tion without the heart, and also of giving the impulsive power to the veins. This independent action in the capillary system, if one part of the body can in any sense be said to be indepen- dent of every other part, seems most likely true, as there are some animals low in the scale of being, which are entirely without heart and blood vessels, and possess no other kind of circulation but the capillary, which is re- garded as the primitive or fundamental circulation. THE PORTAL SYSTEM. 87 THE SECOND OR PORTAL SYSTEM OR CIRCULATION. The portal by some physiologists, is considered the primary circula- tion. Meckel remarks, "we are deficient in exact observa- tions relatively to what parts of the vascular system are formed first, either in man or in the mammalia. Never- theless, we may ad- mit, as almost cer- tain, that the veins appear before the arteries, and that the first are those of the umbilical vesicle — for it is proved in birds that the vitelline veins, and particularly the om- phalo-mesenteric, are soonest developed. Now, the umbili- cal vesicle, in man, corresponds exactly with the vitelline sac of birds." "As to the mode of development of the vessels," continues this Anatomist, "we learn the following from what occurs in the egg. When at some distance from the embryo, we see in the membrane of the yolk, which is at first homoge- neous, certain rounded, circumscribed rents, which are filled with a mass more fluid. These rents are at first entirely separated from each other, and appear like islands in the FIG. 6. The vena-portarum — a inferior mesenteric vein. 6 The pancreas. c The splenic vein, d The spleen. « Gastric veins uniting with the splenic. / Superior mesenteric vein, g Descending portion of duodenum, h Transverse portion, i Vena portarum. j Hepatic artery, k Ductus communis, chole- dochus. I Division of vessels and duct at the transverse fissure of the lever. m Cystic duct. 88 THE PORTAL SYSTEM. rest of the mass — new lacunas are gradually formed in the substance of the membrane of the yolk, which increase the number of islands, and give rise to a fine net work of ves- sels, which ramify exceedingly — these soon contain real blood, instead of the clear, thin fluid which first filled them. This vascular net-work is the commencement of the ompha- lo-mesenteric vein — its trunk is not the first portion formed, but the ends of the vessel appear soonest, these gradually unite into branches and finally produce the trunk. When the omphalo-mesenteric vein is thus once formed, the rest of the vascular system produces itself as follows: "The vein bends from below upwards, and dilates on the anterior face of the body of the foetus to form the heart. From this the trunk of the arteries of the body arises, which carries the blood to the organs, and after this we see the accompanying veins. The vessel into which the omphalo-mesenteric vein opens, or to speak more exactly, into which it is changed, is the vena portae. This, which at a later epoch finds itself simply enclosed in the general system of the veins of the body, constitutes at present the principal trunk, and at its upper part produces the heart." The portal system, in connection with the general and pulmonary, have each a common form, which is compared to a tree consisting of a trunk, branches, twigs, and ramus- cules. The portal, situated entirely within the abdominal cavity, has its trunk about three inches in length, lying between the duodenum and the liver. Its roots are the numerous capillaries arising from the small and large intes- tines, the stomach, pancreas, and spleen, while the almost endless divisions and subdivisions in the liver, are the different branches and twigs of the tree. The liver is viewed as the centre of this circulation. The structure of the portal vessels consists of three mem- branes, an external, middle, and internal. The first is a con- densed cellular tissue, not so strong as in the arteries. The second is fibrous and contractile, and by some considered muscular, having its fibres running longitudinally; while the third is a delicate serous membrane, having a smooth THE GENERAL CIRCULATION. 89 polish, and, according to Henle, an epithelium composed of vesicles and scales, analogous to those of serous and mucous membranes. The portal vessels are veins, but differ from other veins in not having any valves. They are endowed with the properties of contractility, extensibility, and elasticity. Their function is to convey venous blood, of the darkest kind, from the abdominal digestive organs, except the liver, to this gland, where the bile is separated from it. The ductus venosus is the connecting link between the portal and the next or general circulation. THE THIRD OR GENERAL CIRCULATION. The general circulation is styled the true, or Circulation Proper. It commences in the left ventricle of the heart by the aorta, extends and ramifies through every part of the body, and then returns, by the vena cava, back again to the heart upon its right side, thus completing the circle. From this mode of distribution, we have the/orm of two trees — one the aorta, the other the vena cava — the former carrying the blood from the centre to the circumfer- ence, the latter bringing it back changed, from the circumference to the centre. The heart is the centre. The heart, arteries and veins, then, com- prise the three natural divisions of the gen- eral circulation. M. Bichat makes two great divisions of this circulation. 1st. The vascular system of red blood. 2d. The vascular system of black blood. The first division commencing in the lungs, with the red FIG. 7 represents the blood moving in a circle. 1, 1, Superior and Inferior Cava. 2, Right Auricle. 3, Left Ventricle. 4, 4, Aorta and common Carotid Artery. 90 THE GENERAL CIRCULATION. blood, by the pulmonary veins, proceeding from thence to the left side of the heart, thence by the aorta, to every part of the body. The second division beginning with the black blood, in the extremities and circumference of the body, and proceeding thence to the lungs, its place of termination. It will be seen that this mode of division includes an- other and distinct circulation in the lungs, to be noticed in another place. The direction of the vessels belonging to the vascular system, with some exceptions, is generally straight, and proceeds in right lines. All its different divisions have free communication, the one with the other, as the capillary, portal, general, and pulmonary. So likewise with the several parts composing each division. This mode of connection is called Anasto- mosis, (from cwa, through, and $ Arteries. 5. Splenic, ) 6. Superior Mesenteric. 7. Renal Capsular. 8. Emulgent. 9. Spermatic. 10. Inferior Mesenteric. 11. Lumbar. 12. Middle Sacral Artery. R. Common Iliac Artery, divided into S. Internal Iliac— branches, 1. Obturator. 2. Glutial. 3. Ischiatic. 4. Internal Pudic. T. External Iliac— 2d division of com- mon Iliac — branches, 1. Epigastric. 2. Circumflexa Ilii. U. Femoral Artery— 3. Profunda JFe- moris — branches, 1. External Circumflex. 2. Internal Circumflex. 3. Perforantes. V. Popliteal Artery — branches, 1. Superior External Articular. 2. Superior Internal Articular. 3. Middle Articular. 4. Inferior External Articular. 5. Inferior Internal Articular. X. Anterior Tibial Artery— branches, 1. Recurrens Tibialis. 2. Internal Malleolar. 3. External Malleolar. Y. Posterior Tibial Artery— branches, 1. External Plantar. 2. Internal Plantar. a, b, c, d, e, f, digital branches. Z. Fibular Artery — branches, 1. Anterior. 2. Posterior. FIG. 8. I! s rl P CD •< CD 1 ff S3 96 THE ARTERIAL TREE. The aorta, the great trunk of this tree, has its origin in the superior part of the left ventricle of the heart; ascends behind the pulmonary artery to the right side, on a level with the articulation of the second rib with its cartilage, then crosses transversely about an inch below the upper edge of the sternum to the left side, where it makes a second turn downwards and inwards to the bodies of the third or fourth dorsal vertebra). This course of the aorta describes a curve called its arch, consisting of an ascending, trans- verse, and descending portions. From the arch we follow the aorta descending through the thorax upon the left side of the vertebral column to the diaphragm, beneath the crura of which muscle it passes, and thence continues to descend on the median line to the space between the fourth and fifth lumbar vertebra, where it terminates, dividing into the common iliacs. The portion above the diaphragm, beginning with the arch, is called the thoracic aorta — the portion below is the abdominal aorta. The first branches given off by the aorta after leaving the heart, are the coronary arteries — two in number — the right and left, which supply the right and left portions of the heart. The next in order are those coming off from the arch, which are the arteria innominata, the left carotid, and the left subclavian. These are large and important branches, supplying, with arterial blood, the head, neck, and superior extremities. The arteria innominata, after proceeding about an inch and a quarter, divides into two branches, the right carotid and the right subclavian. The former passes up the right side of the neck to opposite the corner of the os-hyoides, where it again divides into the external and internal carotid arteries, the former supplying the right side of the face and the right and posterior parts of the head, together with the right upper neck, while the latter enters within the cranium and supplies the right half of the brain. The left carotid, arising from the arch of the aorta, pursues a similar course upwards upon the left side of the DISTRIBUTION OF THE ARTERIES. 97 neck, has a similar division at the os-hyoides, into exter- nal and internal carotids, supplies with a like number of branches the left upper half of the neck, face, side and posterior parts of the head; while the left internal carotid supplies the left half of the brain. The whole number of branches,, of any magnitude, which belong to the carotids upon both sides of the neck, are about 22; 16 of this number going to the upper neck and exterior head, while the remaining supply the brain. The subclavian artery, having its origin on the right side from the arteria innominata, and on the left from the arch of the aorta proceeds in the first stage of its course to the scaleni muscles, between the anterior and middle of which it passes. It then proceeds between the clavicle and first rib to the tendons of the latissimus dorsi and teres major muscles, over which it passes, completing the second stage of its course. We now follow it down the arm along the inner edge of the biceps muscle, upon the brachialis anticus to a little below the elbow joint, forming its third and last stage, where it divides into the radial and ulnar arteries, which supply the forearm and hand. These three stages have received distinct names — the first stage is called the subclavian, the second the axillary, the third the humeral. Five branches belong to the first, eight to the second, and six to the third stage. The whole number of primary branches belonging to the two subclavian arteries, which supply the upper extremities, is about 38. The chest and its organs are next in order as we pro- ceed down the body and follow the course of the arterial trunk. The aorta having made its curve, gives off the bronchial arteries to the lungs; the oesophageal branches, five or six in number, to the oesophagus; posterior mediastinal branches, as the name imports, to the mediastinum; and ten intercostal branches to the intercostal spaces and walls of the chest — the two upper intercostal spaces being sup- plied from the subclavian. These arteries being all in pairs, the whole number supplying the chest is about 40, 7 98 DISTRIBUTION OF THE ARTERIES. The aorta having passed the diaphragm, "becomes abdorn- inal and distributes its branches in the following order. 1. The phrenic, two in number, to the diaphragm. 2. The cceliac, a single trunk, which divides into three branches that supply the stomach, liver and spleen, called the gastric, hepatic and splenic arteries. 3. The superior mes- entericj about half an inch below the eceliac, sends off innu- merable branches which go to the small intestine, and the ascending and transverse portion of the" large. 4. The emul- gent arteries come from the aorta at right angles, and go to the right and left kidneys. 5. The spermatic going to the testicles, are small and of great length. 6. The inferior mesenteric is a single trunk, supplying the left colon. *7. The lumbar arteries, from three to five in number, supply the walls of the abdomen. These are all the primary branches given off by the abdominal aorta to its termina- tion, and are about 19 in number. The whole number sent off by the arterial trunk from its commencement to its ter- mination, counting the two terminating branches, is about 66 — five from the curve, forty from the thoracic, and twenty-one from the abdominal aorta. The aorta, as already stated, terminates at the space be- tween the fourth and fifth lumbar vertebrae, from whence proceed the common iliacs, which go to the sacro-iliac sym- physis, and there divide into two main branches, the inter- nal and external iliac arteries. The former supply the pelvic cavity and its viscera, the latter go to the inferior extremities. The principal branches of the internal iliac or hypogas- tric artery are, 1, the ilio lumbar; 2, the lateral sacral; 3, the obturator; 4, the middle haamorrhoidal ; 5, the uterine peculiar to females; 6, the vesical; f, the gluteal; 8, ischiatic, which go to the rectum, bladder, vesiculae serninales, pros- tate gland, and walls of the pelvis, while the same branches supply the vagina, uterus, ovaries and common parts of the female. The external iliac artery is so called till it reaches Pou- part's ligament, when it becomes femoral. It gives off but VENOUS CIRCULATION. 99 two branches in its course, and these at its termination: 1, the epigastric, and, 2, circumflexa ilii. The femoral artery, commencing at Poupart's ligament, is to he found at a point half way between the anterior supe- rior spinous process of the ilium, and the symphysis puhis, situated behind this ligament and upon the common union of the psoas magnus, and iliacus internus muscles; thence it crosses the pectinalis, adductor brevis and longus, along the inner edge of the rectus, and behind the sartorius to the tendon of the adductor magnus, which it perforates. There it becomes popliteal and continues such to the aperture in the interosseous ligament of the leg, where it divides into anterior and posterior tibial arteries, supplying the leg and foot. The femoral arteries give off each four principal branches to the thigh ; the popliteal, five to the knee-joint, and the two terminating branches of the popliteal, to the leg and foot. The whole number of primary branches supplying the lower extremity, is about 28. The whole number to the body is 132 — 66 to the trunk, and 66 to the extremities. This is the most usual way in which the arterial system is distributed, but we shall frequently find varieties in the origin, course, size, and number of the primary branches. The venous tree has its commencement where the arte- rial terminates, or more properly, from the capillaries, the connecting link between the two. The venous system con- sists of two trunks, called the inferior or ascending, and the superior or descending cava. These two trunks, with the coronary vein, return to the heart all the blood of the body. We trace the primary branches of the venous trunks in a direction contrary to the arterial, that is, from the circumference to the heart, instead of from the heart to the circumference. In the inferior extremity, commencing in the foot, we trace the venous radicles, forming the superficial and deep- seated veins. The superficial are the external and internal saphena, the former rising upon the anterior and external part of the 100 VENOUS CIRCULATION. dorsum of the foot, the latter upon the internal and plantar portion. After free anastomosis, the external ascends upon the outer side of the leg and terminates in the popliteal, while the internal runs up on the inner side of the leg and thigh, and ends in the femoral vein, a short dis- tance below Poupart's ligament. The deep-seated veins have all the same course, and the same' name with the arteries they accompany ; every artery except the larger trunks having two veins called the venas comites. Hence we follow the veins attending the anterior and posterior tibial arteries, with the peroneal, ascending the leg and by their com- mon junction at the posterior part of the knee joint, forming the popli- teal vein. The popliteal vein takes the same course as the artery, to the tendon of the adductor magnus, where it becomes femoral. It now ascends to Poupart's ligament, along with the artery, and upon its inner side at the upper part of the thigh, where it becomes the external iliac vein, this unites with the internal iliac vein from the interior of the pelvis, forming the com- mon iliac veins on either side, which at the fourth lumbar vertebra unite together and constitute the inferior cava, or FIG. 9 represents the trunks and principal branches of the venous system. 1 Descending vena cava. 2 Left vena innominata. 3 Right vena innomina- ta. 4 Right subclavian vein. 5 Internal jugular vein. 6 External jugular. 7 Anterior jugular. 8 Inferior vena cava. 9 External iliac vein. 10 In- ternal iliac. 11 Primitive iliac. 12 Lumbar veins. 13 Right spermatic. 14 Left spermatic vein. 15 Right emulgent vein. 16 Trunk of hepatic veins. 17 Vena azygos. 18 Hemi-azygos. 19 Communicating with left renal vein. 20 Union of hemi-azygos with vena azygos. 21 Superior inter- costal vein. PULMONARY CIRCULATION. 101 lower trunk of the venous system. This trunk ascends the abdomen on the right of the aorta, receiving in its course all the tributary branches, (except those forming the vena portas,) to the diaphragm, through which it passes direct to the right auricle of the heart. This vessel returns all the blood of the inferior half of the body. In the superior portion of the body we commence with the sinuses of the brain, which, emerging at the base of the cranium, become the internal jugulars. These descend the neck, and, with the external jugulars, unite with the subclavian at the base of the neck, and form the vena in- nominata, which, with the vena azygos coming together upon the right side, constitute the superior cava. This vessel then descends to the right auricle, entering at its top. This brings us to the next circulation in order, the Pulmonary. This is also called the lesser circulation, in contradistinction to the general, styled the greater or sys- temic. It occupies a position intermediate between the venous and arterial trunks of the general circulation, by ending the former and commencing the latter. The trunk of this circulation begins in the upper portion of the right ven- tricle of the heart, and after a short distance divides into two primary branches, which go to the lungs; these, in turn, again divide and subdivide into countless numbers, which distribute themselves in the form of a net-work over the air cells, which is called the rete malpighi. Here it is that the black blood, brought by the pulmonary artery, changes its color to that of red. Here commence the pulmonary veins; and here in breathing animals begins the arterial circula- tion. The pulmonary veins — four in number, two for each lung — take the blood thus changed, and convey it to the left ventricle of the heart, where ends the lesser or pul- monary, and begins the greater or general circulation. The Structure is the same as that of the arteries and veins already described. There is one remarkable peculiarity in this circulation, deserving notice. It is this : that its arteries carry venous 102 THE HEART. blood, while its veins carry arterial blood — nothing of the kind being found in any other arteries or veins of the adult body. In the foetus, however, the umbilical vein carries red blood, and the internal iliac arteries black, but these after birth become obliterated. The Heart is the centre of the general and pulmonary circulations. It is situated in the middle mediastinum, be- tween the lungs and behind the sternum. Its form is that of a cone, the apex being at the junction of the fifth rib and its cartilage on the left, the base above and obliquely to the right. It is a hollow mus- cle, having four cavities, two auricles, and two ventricles. The auricles are above, and form the base. The ventricles are below, and compose the body and apex. The heart, after birth, is duplicate, and consists of two hearts, right and left. (Fig. 11.) The right heart, composed of the right auricle and ven- tricle, contains venous blood; the left, consisting of the left auricle and ventricle, has arterial. The right heart receives the trunks of the venous tree. The left gives off the trunk of the arterial tree. It is enclosed in a strong fibrous capsule, which connects it below with the dia- phragm, and above with the great blood vessels arising from its superior portion. Its interior has valves to pre- vent the blood from retrograding. There are two sets, one to each heart. The right heart has, at the ostium veno- FIG. 10 represents an anterior view of the heart in a vertical position. a Base. 6 Body and right ventricle, c Apex, d Pulmonary artery, e Right auricle. / Superior cava. g Anterior coronary artery, h Left ventricle. i Left auricle, j Aorta, k Arteria innominata. I Common carotid, nt Left subclavian. THE HEART. 103 sum, the tricus- FlG> pid valve. The left heart, at the os- tium arteriosum, has the mitral valve. For fur- ther description see organs of cir- culation. The heart, ar- teries, and veins, are the three great and fundamental links in the hu- man adult circu- lation, each of which is dependent upon the other, and to strike out either would destroy the entire function. Notwithstand- ing each of these parts has its own proper and especial duty to perform, in carrying on the circulation, still, there are some who limit this action to one or more parts, and deny the rest any share in its performance. The heart, for instance, was supposed by Harvey, the dis- coverer of the circulation, and others, to be the sole agent in this function, and that it was accomplished by means of its muscular structure. Hence the various calculations that have been made of the power of the heart's contraction. Borelli estimated it at 180,000 pounds, while Reil only made it from 5 to 8 ounces. These are the two extremes — very wide apart and unsatisfactory, the former be- ing sufficient to rend the body in atoms, the latter too feeble to be thought for a moment sufficient to drive the blood from the heart to every part of the body, and then back again to the heart. Hence Bichat introduces the ca- pillaries to supply the deficient power of the heart. Dr. Barry FIG. 11 represents the heart double. 1, 1 Superior and inferior cava. 2 Right auricle. 3 Right ventricle. 4 Pulmonary artery. 5 Branches from arch of aorta. 6 Left auricle. 7 Left ventricle. 8, 8 Aorta. 104 DEVELOPMENT OP THE CIRCULATION. believes the venous circulation to be performed entirely un- der the influence of the respiration — that during the expan- sion of the chest a vacuum is produced in the heart, which the blood rushes in to supply — but, unfortunately for this theory, the foetal circulation goes on when there is no respi- ration. Others, with more liberality, and no doubt with greater truth, allow each part of the vascular tissue its ap- propriate office, and suppose each to be equally essential in its place to perfect regularity and harmony in this function. The Development of the circulation begins with the veins, as has been traced in the Portal system to the vena cava, at the upper part of which is the heart. "The heart," says Meckel, "appears at first like a half ring lying loose — the portion first seen is the left ventricle, immediately after, the aorta shows itself, appearing as a considerable dilatation. A little later, the upper extremity of the vein dilates, then contracts before the venous trunk, and thus produces the auricles. "All the parts which are finally double are still single at this period. The auricle first becomes double ; an imper- fect septum descends from its circumference and floats in its cavity, so that the two parts communicate by a very broad opening, the inter auricular canal, called afterwards the foramen ovale, and still later, the fossa ovalis. "The doubling of the ventricle does not take place in the same manner, but is produced by the prolongation of the primitive portion at its upper part. The right ventricle appears first as a small tubercle which gradually extends itself towards the summit of the heart and communicates with the left ventricle. This communication takes place at the upper part of the two ventricles, because at first the left cavity only prolongs itself. Hence the aorta arises at first from both ventricles. "The pulmonary artery is the last to detach itself so as to constitute a distinct trunk, but it was indicated before along the aorta. In fact the aorta, which at first arises solely from the heart, divides at some distance from this organ into two branches at least, and as the aorta is blended FCETAL CIRCULATION. 105 gradually with the ventricle, the bifurcation is depressed also; and when one of the two branches separates itself entirely from the other, by completing the formation of the opposite portions of their circumference, the pulmonary appears, forming a distinct pJG> 12. trunk. But as the cavities of the heart communicate, the pulmonary continues not only at first,, but during the whole of foetal existence, with the aorta of which it constitutes the second root." The lymphatic circulation will be noticed under the head of the glandular tissue. We will conclude the vas- cular tissue by briefly point- ing out the difference between the circulation in the foetus and the adult. This difference is seen first (Fig. 12) in the heart. Here, in the foetus, the auricles com- municate by the foramen ovale, which after birth is closed. At the mouth of the inferior cava there is a valve in the foetus, which disappears in the adult. The pulmonary artery in the foetus communicates with the aorta by the ductus arteriosus, which in the adult is closed. 2d. The internal iliac arteries of the foetus carry venous FIG. 12 represents the foatal circulation, o Umbilical cord. 6 Placenta. e Umbilical vein dividing into three branches, dd Two of which go to the Liver, e The third is the ductus venous, which goes to the inferior cava. fg Por- tal vein, h Right auricle. £ Left auricle, j Left ventricle, k Arch of aorta. I m Show the return of blood by the jugular and subclavian veins, n Superior cava. o Right ventricle, p Pulmonary artery, q Ductus arteriosus. r Descending aorta, s Hypogastric'or internal iliacs. t External iliacs. 106 FCETAL CIRCULATION. blood to the placenta. These in the adult are closed and become the superior ligaments of the bladder. 3d. The umbilical vein, which carries the blood from the placenta to the foetus, is in the adult obliterated; that por- tion between the umbilicus and the liver, becoming the round ligament of the liver ; while the remaining portion connecting with the hepatic vein, and thence with the vena cava inferior, is the closed cord of the ductus venosus. 4th. The placenta, which, after birth, is detached from the umbilical cord. The human placenta is described as consisting of two portions, the one belonging to the foetus, the other to the uterus of the mother; dense tufts of vascular villi compose the foetal portion, while the maternal portion is formed of the decidua of the uterus, which receives the foetal villi — thus formed, it is the medium of nourishment to the foetus during the period of utero-gestation. CHAPTER IV. THE NERVOUS TISSUE. ANALYSIS. IMPORTANCE, DIVISIONS ACCORDING TO BICHAT, SITUATION, EXTENT, SYM- METRY, DIVISIONS ACCORDING TO DEVELOPMENT, COMPOSITION, FUNCTIONS, RELATIONS. THE nervous system, says M. Cuvier, constitutes the ani- mal, and the other systems are provided in order to serve and maintain it. It is regarded as presiding over all the functions of the body, as being the source of all sensation and motion, as regulating the temperature and controlling the different secretions. The importance of this tissue then, cannot be too highly estimated as forming one of the fundamental elements entering into the constitution of the several organs. According to Bichat, it is divided, 1. Into the nervous system of animal life. 2. The nervous system of organic life. THE NERVOUS TISSUE. 107 The first division, so called as it belongs especially to animals, connects them with the external world, and is hence classed among the organs of relation ; while the second division has its appellation from belonging to the functions of nutrition, which are common to the whole or- ganic world, and constituting organic or vegetative life. The first division is situated partly within the cavity of the cranium and vertebral canal, and is the central portion of the system ; while the remaining part extends to the cir- cumference of the body, and is denominated the radiating or peripheral portion. The second division seems to occupy almost exclusively the trunk, and extends in a chain of gan- glia, the whole length of the vertebral column, upon either side. The first division is symmetrical, that is, consists of two equal and similar parts upon either side of the median line of the body ; while the second division is in a great measure destitute of this symmetry. In giving a general outline of the nervous tissue, we will adopt that division which is most in accordance with its development, thus connecting its Anatomy with its Physi- ology. The order will be, 1. The Nerve and Ganglia. 2. The Spinal Marrow. 3. Medulla Oblongata. 4. The Brain. The nervous system in animals low in the scale, is seen in the form of a double cord ; a step higher, upon one extremity of this cord are developed knots or ganglia. In the lowest vertebrata, as the fish, five pairs of ganglia are found in succession, upon the anterior extremity of this double cord. In the higher fishes and amphibia, these primitive ganglia have a different disposition. The first two pairs become fused together, forming a single ganglion, or rather are hid by a thin membrane, leaving the three pairs of symmetrical ganglia. This arrangement is traced upwards into the mammalia, where, as in the dog, is seen this single ganglion constituting the cerebellum, and the 108 THE NERVOUS TISSUE. three pairs, as before, in succession ; and by unveiling this single one, the two primitive pair of Ganglia are revealed, which are now hid by an additional development. These Ganglia, at first disjointed, become connected by transverse fibres, called commissures. The order, then, of development in the lower amimals seems clearly to be, first, primitive cords, second, Ganglia, and third, commissures uniting these Ganglia and associa- ting their functions. In the development of the nervous system of man, there are also first seen two filaments or cords, placed side by side longitudinally, and upon these cords at the upper ex- tremity are five pairs of Ganglia. In an after period these two filaments become united and form the spinal cord, except at their superior end, where they continue apart in the crura cerebri. The first pair of Ganglia are developed into the Cerebellum. The second pair, in animals the optic lobes, have in man become the Tubercula Quadrigemina. The third pair form the Optic Thalami, and the fourth the Corpora Striata,the basis of theHem- ispheres, while the fifth, very large in the lower animals, are small in man and form the olfactory bulbs. Thus the same order of development in the nervous tissue is established in man as in the lower animals : 1. The primitive fibres or cords. 2. Ganglia upon these cords. 3. Com- missures connecting these Ganglia — and finally, develop- ment from these Ganglia into the mature and perfect Brain. The Nervous Tissue wherever examined, is seen to be FIG. 13 represents the minute structure of nerve. a Loop termination of nerve fibres — one of the loops is convoluted and three are simple. 6 Represents the varicose appearance of a white nerve fibre from the brain, which is made so by pressure or traction, c A white nerve fibre enlarged to exhibit its structure, which is seen to be tubular, and containing a substance called neurine. d A nerve cell, showing its granular contents, e Nucleus and nucleolus. / Processes given off from a nerve cell. g Nerve granules. THE NERVOUS TISSUE. 109 composed of two substances, the one white, the other gray, or cineritious. Under the microscope the white substance is found to consist of fibres forming perfect cylinders, and varying in diameter, having, according to Solly, an average diameter of 1-2000 to 1-4000 of an inch. They consist of a trans- parent neurilemma, containing a soft homogeneous sub- stance, which on pressure assumes the knotted form, as seen in 5, figure 13. This white substance constitutes the whole of the nervous trunks and a large part of the central masses. Its chemical constitution, by the analysis of Mr. John, is Water 73, Albumen 9.9, White fatty matter 13.9, Bed fatty matter 0.9, Osmazome 1, Earthy Phosphates 1.3. Besides these tubular fibres of the white nervous matter, there are others belonging to the sympathetic nerves, which are found to be only about half the diameter of these fibres. They are of a grayish color and are called organic fibres. The gray portion of nervous tissue, according to the microscope, consists of spherical globules, containing a nucleus with nucleoli, having a very fine filamentous cov- ering and connected by processes to surrounding globules. These globules are from 1-3000 to 1-1250 of an inch in diameter. This gray matter forms the outer covering of the Hemispheres of the brain, and is there called Cortical or Cineritious. It exists in the interior of the spinal cord, and composes the centre of the Ganglia. Its chemical constitution, according to the same chemist, is Water 85, Albumen 7.5, White fatty matter 1, Eed fatty matter 3.7, Osmazome 1.4, Earthy Phosphates 1.2. The gray matter is regarded as the source of nervous power, and its collection at various points constitutes the nervous Ganglia, which are regarded as so many independent centres of nervous action; while the white matter and its fibres are considered the conductors of the nervous energy. The white and gray matter in varying proportions 110 THE NERVOUS TISSUE. form, the Brain, the analysis of which, according to Vau- quelin, is Albumen, »• Cerebral fat, Phosphorus, Osmazome, Acids, Salts, Sulphur, Water, 100.00 The Nerves. — The primitive fibres already spoken of, collected in bundles and surrounded by a sheath, their neurilemma, constitute a nerve. Nerves are of various kinds, which the dissections and experiments of Sir Charles Bell most clearly demonstrate. He distinguishes nerves of Motion, nerves of Sensation, and Kespiratory nerves. Dr. Hall has since added, what he calls, the Excito-Motor nerves. The nerves, composed of many filaments, have their roots or origin in a line or streak of nervous matter, as seen in the Brain, which is called a Tract. When these streaks are raised, the term rod or column is applied, as the anterior and posterior rods of the spinal marrow. These tracts and columns of nervous matter, are consid- ered the sources of endowment to all the nerves originating in them, and the different endowments and peculiar func- tions of each are owing to the fact of their arising from different nervous tracts. All nerves arising from the same tract, have the same endowment their whole length, from origin to termi- nation. For example, if we take a filament of a nerve whose office is to convey sensation, that power will belong to it in all its course, whether traced in the foot, leg, spine or brain. When pricked or injured in any way, sensation, and not motion, will be the result, and the perception of the impression will be referred to that part of the skin where the remote extremity of the filament is distributed. THE NERVES. Ill But nerves arising from different tracts may be enclosed in the same bundle, and this may consequently have different endowments. Hence the distinction into simple and compound nerves. Those filaments coming from the same tract are called Funiculi, and form simple nerves. Those coming from different tracts are called Fasciculi, and form the compound nerves. The ninth is a simple, the spinal are compound nerves. The course of the nerve fibres is straight, and without branches, from their origin to their termination. A communication of nerves by means of their funiculi and fasciculi, forms a kind of net work called Plexus; the nerves, however, do not run into each other and form an anastomosis after the manner of blood vesse.ls ; they simply come together, enter each other's sheaths, run side by side, but are not fused into one. The use of a plexus is two-fold. 1st. It intermixes fibres of fundamentally different endowments, as the spinal ac- cessory and par vagum — the former a motor, the latter a nerve of sensation. 2d. It advantageously distributes nerves of the same endowments, as in the Brachial plexus, where the filaments of five segments of the spinal cord are mixed together, and proceed in this mixed state to the several parts upon which they are distributed. By which arrangement no part can be paralyzed, till all the five segments or centres of action are destroyed — while if each centre sent its nerves singly and alone to any part, when that centre becomes destroyed, the part upon which its nerves are spent will inevitably suffer paralysis. The nerves terminate (Fig. 13) in loops or arches, or more properly speaking, they have no free extremity, but form circles; those, for instance, going from the spinal marrow and brain to the circumference of the body, which conduct the motor power, and called efferent — while the afferent, which begin where the others stop, are contin- ued back again to the place from whence they started — thus completing the circle, and conducting to the central nervous ganglia, sensory impressions. 112 SPINAL MARROW. The order, FIG. origin of the nerves brings us to the part next in which is the SPINAL MARROW. The primitive longitudinal filaments, al- ready noticed, coming together and growing, swell into the spinal cord. This cord, or marrow, occupies the bony vertebral canal, extending from the atlas to the second lumbar vetebra, where it termi- nates in the cauda-equina. It is surrounded by three membranes — the dura-mater, tunica arachnoidea, and pia mater — the first a fibrous, the second a serous, the third a vascular mem- brane. The spinal marrow presents the form of a cylinder having several enlargements in its course, corresponding to the points where the large plexuses are given off as the brachial and lumbar. It is divided in front and behind, by two fissures, anterior and posterior ; thus sep- arating it into two equal and lateral halves. These two halves are again divided by a lateral line, which consequently cuts the cord into four parts — two anterior, and two posterior. These parts receive the name of nervous tracts, rods or columns. Their outer surface is white or medullary, while the inner is gray or cineritious. There is still another tract placed between the anterior and posterior columns, called by FIG. 14. Anterior view of Spinal Marrow. o Dots showing corpora pyramidalia. 6 Corpora olivaria. c Anterior face of spinal marrow, d Anterior roots of cervical nerves, e Anterior roots of dorsal nerves. /Anterior roots of lumbar nerves, g Anterior roots of sacral nerves, h, t, j, k Anterior and posterior roots joined to pass out of the dura- mater. I Dura-mater of spinal cord, m, n, o, p Ganglia on cervical, dorsal lumbar and sacral nerves, q Cauda equina. r Sub-occipital nerve, s Liga- mentum denticulatum. SPINAL MARROW. 113 Mr. Bell the respiratory tract, which, with the anterior, forms what is termed antero-lateral. These different columns give origin to different nerves having different endowments. FIG. 15. The anterior give off the nerves of motion, and the posterior those of sensation, the latter distinguished by hav- ing a ganglion on their root. And the middle portion supplies the respiratory nerves. There is still another set of nerves described by Mr. M. Hall, as having their centre in, and belonging most especially to the spinal marrow, called the excito-motory, or reflex nerves, having an action entirely independent of volition, and conse- quently having the power, as proved by experiment, of producing muscular movement when the brain is absent. The fibres, over which the brain exerts its influence in producing voluntary motion, do not stop in the spinal mar- row, but, according to Mr. Solly, curve upwards and extend to the brain, thus explaining most satisfactorily why it is that apoplexy, by compressing these cerebral fibres, should produce a loss of voluntary motion and sensation, while those that are free and uncompressed in the spinal cord FIG. 15. Section of the spinal marrow, with its membranes. a Dura mater. 6 6 Dura mater forming a sheath for each of the roots of a spinal nerve, and afterwards a sheath for the nerve itself, c c Sheath around each of the roots of the spinal nerve, by the arachnoid, during its passage through that membrane. The dotted line represents the arachnoid, d Space between two layers of arachnoid, e Space between arachnoid and pia mater. /One of the dentations of the ligamentum-denticulatum. g g Pia mater, h An- terior median fissure, i White commissure connecting the lateral halves of the cord, j Grey commissure connecting the two semilunar processes of gray sub- stance, k Posterior median fissure. 1 1 Antero-lateral columns of spinal cord. m m Two lateral columns, n Posterior columns, o o Posterior median columns. p Origin of anterior or motor root of spinal nerve, q Origin of posterior or sensitive root, r Ganglion on posterior root, s Spinal nerve separating into its two primary divisions, anterior and posterior. 8 114 MEPULLA OBLONGATA. should still remain actively alive to all impressions, and produce a variety of corresponding motions without volition or any consciousness whatever. A step higher and we find these nervous columns of the spinal marrow continued into or surmounted by the Medulla OUongata. FIG. 16. FIG. 16. Base of the brain with its nerves. a Anterior fissure between hemispheres of the Brain. 6 Posterior fissure. c Anterior lobes of Cerebrum, d Middle lobes, t Fissure of Sylvius. / Posterior lobes of Cerebrum, g Point of Infundibulum. h Its body, i Corpora Albicantia. j Cineritious matter, k Crura Cerebri. I Pons Va- rolii. m Top of Medulla Oblongata. n Posterior prolongation of Pons Varolii. o Middle of Cerebellum, p Anterior part of Cerebellum, q Its Posterior fissure, r Superior part of Medulla Spinalis. s Middle fissure of Medulla Oblongata. t Corpus Pyramidale. tt Corpus Restiforme. v Cor- pus Olivare. w Olfactory Nerve, x Its bulb, y Its external root, z Middle root, aa Internal root, bb Optic nerve beyond Chiasm. cc Optic nerve before the Chiasm. dd Motor Occuli, or third pair of nerves, ee Fourth pair or pathetic nerves, ff Fifth pair or Trigemini nerves, gg Sixth pair or Motor Externus. hk Facial nerve, ii Seventh pair Qr Audi- tory, including Facial, jj kk II Eighth pair of nerves— ninth not seen. MEDULLA OBLONGATA. 115 The Medulla Oblongata is within the cranium, lying upon the cuneiform process of the occipital bone, has the same arrangement of the white and gray matter as the spinal marrow, and by Mr. Salandier is regarded as the foundation of the central organs. It is composed of six eminences, the corpora pyramidalia, the corpora olivaria, and -the corpora restiformia — which are nothing more than the enlargements of the nervous tracts belonging to the spinal marrow. The corpora pyramidalia correspond to the motor tract; the corpora olivaria to the respiratory, and the corpora restiformia to the sensory. From the corpora pyramidalia nervous filaments can be traced through the pons varolii, crura cerebri, thalami, corpora striata, and thence ex- panding to form part of the cerebrum. Some of these filaments decussate low down, those on the right going to the left side of the brain, and those on the left to the right — by which disposition, paralysis on the opposite side of the body from injury of the head is explained. The corpora olivaria are by Mr. Solly regarded as chiefly motor, and fibres can be traced from them through the pons to the tubercula quadrigemina, or optic ganglia, and thence along with the fibres of the corpora pyramidalia to the cerebrum, some also going to the cerebellum. Hence the cerebrum is by Gall and Spurzheim, who take this as their starting point, said to be formed or developed from the corpora pyamidalia and olivaria — while the remain- ing tract, the corpus restiforme, is as clearly traced into the cerebellum. The corpus restiforme differs from the others, according to the dissections of Mr. Solly, in having its fibres inter- lacing instead of parallel. Most of the cranial nerves arise from the Medulla Ob- longata; and from this fundamental point as a centre, the primitive filaments have been traced, radiating to the cir- cumference of the cerebrum and the cerebellum — these are called diverging fibres. Another set is traced from the circumference back to the centre — these are the converging 116 THE BRAIN. fibres. The two sets intersect each other, having spaces termed ventricles, while the converging fibres constitute the Commissures of the Brain. The Brain, (Fig. 16,) filling the cavity of the Cranium, is, like all other portions of nervous tissue, composed of white and gray matter, but differently arranged, the white occupying the centre, while the gray covers the surface. We however find both kinds, in variable quantity, interspersed throughout the Brain. The Brain is divided into Cerebrum and Cerebellum. The former is again di- vided into hemispheres, and these subdivided into lobes. The surface of the Cerebrum is thrown into convolutions, which are regarded as the organs of intelligence. The relation which the Brain, Spinal Marrow, and their nerves, sustain to each other is so intimate as to unite them all in a circle of communication and action. The Brain, forming the central organ of perception, receives the impressions — the Spinal Marrow and nerves of Sen- sation convey these impressions, while the nerves of Mo- tion carry out the mandates of the Brain to the different muscles of the body — thus forming a circle of conduc- tion, perception, and action. This tissue has likewise the closest relation with all the organs and functions of the body. The second great division of the nervous system is that of organic Life. It belongs to the trunk, is connected with the organs of nutrition, consists of a great number of G-anglia, whence it is called the Granglionic system. These Ganglia are found in the neck, chest and abdomen, and send off an infinity of filaments, which^ running together and in- terlacing, constitute the various plexuses, following and intimately surrounding the arteries, in their route to the several organs. This system is also styled the Sympathetic, as it connects the different parts of the body together — Splanchnic, from its being so largely associated with the various viscera — and, more recently, Automatic, from being regarded as self-moving and the original source of nervous power to every other part. THE GLANDULAR TISSUE. 11T For further details of the sympathetic, turn to the nerves of the Trunk, as connected with the several viscera, particularly those of the abdomen. CHAPTEK V. * JT THE GLANDULAR TISSUE. ANALYSIS. DEFINITION, DIVISION, FORM. GLANDS are organs designed to separate from the blood fluids of a peculiar kind, some of which are concerned in important functions, and again re-enter the system, while others are ejected from the body as not only useless, but highly dangerous to be retained. This definition only applies to those glands having ex- cretory ducts, which in reality are considered as the only true and proper glands, the others being more properly called ganglia. The glands may be arranged under two divisions, 1. Those having excretory ducts. 2. Those without excretory ducts. Under the first head we have the salivary glands, the liver, the pancreas, the kidneys, the testicles, the mammae, the multitude of mucous glands scattered throughout the alimentary tube, and the equally great number belong- ing to the skin. Under the second division we find the lymphatic glands, the thymus, the thyroid, capsulae renales, glandulee Pacchioni, and the pineal gland. Structure. — The simplest form of a gland is the sac or cell follicle, as, for instance, the mucous follicles which consist of a simple depression of mucous membrane, con- tracted at its orifice into a narrow neck. A second form is that of the tube, also composed of a reflection of the mem- brane. By the combination of these two forms, says Pro- fessor Muller, all the varied glands in the human body, as well as in inferior animals, can be constructed. 118 THE GLANDULAR TISSUE. The microscope lias been most industriously employed in the examination of the minute structure of the glands, and to it are we indebted for most of our knowledge on this subject. The combination of the two elementary forms constitutes compound glands, of which two varieties are noticed. 1st. Those whose tubes ramify in an arborescent form. 2d. Where they do not branch off, but preserve the same diameter nearly throughout their whole course. The mammary, salivary and lachrymal glands, with the pancreas and the liver, belong to the first division. This division presents two groups. FIG. 17. 1. The tubes branch off with some de- gree of regularity, the first branches sending off others, and these at certain intervals again divid- ing, till at their ter- minations, to the na- ked eye they present the form of acini lo- bules, or granuli, which, saysMuller, are "only aggregates of cells, seated in clusters on the extremities of the most minute secreting canals or tubes, which cells are only visible by the micro- .scope." These minute tubes sometimes branch off into delicate coeca, as seen in the lachrymal glands of the turtle, or into the form of tufts of twigs in other animals. In the second group, the tubes branch off irregularly and do not terminate in cells, but in tufts or twigs. The liver is given as an example, and though it contains acini, they are nevertheless composed of these tufts or twigs. FIG. 17 represents a portion of the Mammary Gland, and arborescent arrangement of its ducts. 66 cc dd ee Lactiferous ducts and orifices, g g g g Milk cells. /// Excretory ducts from the cells to the larger lac- tiferous ducts. LYMPHATIC GLANDS. 119 The tubes of the second variety, instead of dividing like the branches of a tree, scarcely ramify at all, but proceed on in their course with scarcely any change in their diameter, as in the kidneys and testicles. Here we find the tubes convoluted and of extraordinary length, measuring in the testicle, according to Dr. Munroe, 5208 feet The celebrated Kuysch, from his very minute injections, was led to believe that glands consisted entirely of blood vessels, which had a direct communication with the excre- tory duct But more recent observations, says Muller, show " that the secreting canals in all glands, form an in- dependent system of tubes — that whether they be convo- luted as in the kidney and testes, or ramified in an arbor- escent form, as in the liver and salivary glands ; whether they terminate by twig-like cceca, as in the liver, or in grape-like clusters of cells, as in the salivary glands, pan- creas, and mammary gland ; their only connection with the blood vessels, in all cases, consists in the latter ramifying and forming a capillary net work on their walls, and in their interstices, 'and that the finest secreting tubes are always several times larger in diameter than the minute ramifications of the arteries and veins." The lungs, it is supposed, furnish the best type for the whole series of glandular organs. The general conclusion to which the microscope has led, in reference to the structure of glands, is, that the primi- tive cell is the fundamental and operative part in which all secretion occurs, whether in the simple or complex gland, or in the lengthened secreting tubes, or in the skin or any of the membranes of the body ; and that however various the form of the elementary parts, all the glands, without exception, which secrete a fluid, follow the same law of conformation, by developing themselves from the simple follicle. LYMPHATIC GLANDS. Under this head we will give a general description of the absorbent system, which is as important and interest- ing as the sanguineous. If the latter carries into the 120 LYMPHATIC GLANDS. system the nutrient material for constructing the body, the former conveys out the same material, after it has per- formed its part in the ceconomy, and becomes useless; or rather carries it into the venous blood, to become repurified in the lungs, again to enter the system. This system is divided into the lymphatic glands and the absorbent vessels. The lymphatic or absorbent glands, called also conglo- bate, are very numerous both in the trunk and extremities, and are generally seen in clusters or chains, as in the mesen- tery and neck. Their color is reddish, inclining to a grayish hue, though the bronchial are black and those of the lesser omentum sometimes yellow. Their consistence is firm and resisting. They are surrounded by a firm capsule of cel- lular membrane, which sends processes within their sub- stance to unite the different parts, as blood vessels and nerves, with which they are liberally supplied. Their size varies from that of a currant to that of an almond. Their form is round or oval, though some are irregular and lobulated. They are movable in the healthy state, but become firmly fixed by inflammation. Their structure is not fully determined, though they seem to consist essentially of an interlacement of lymphatic vessels, which enter these glands, and after forming a kind of plexus, leave them. Those entering are called vasa infereritia; those leaving, vasa efferentia. Cells are spoken of as lying between these two kinds of vessels, into which they open, and containing a peculiar fluid. The absorbent vessels are divided into the lymph- atics and lacteals, so called from the color of the fluid they respectively carry, which is transparent in the former and milky in the latter. Some of these vessels were seen in the mesentery of a goat by Herophilus and Erasistratus, 280 years before the Christian era. Aselius, an Italian anatomist, in 1622 re- discovered or confirmed the original observations of absorb- ents in the mesentery, made so long before by Herophilus and Erasistratus, and found that these vessels took up the LYMPHATIC GLANDS. 121 chyle, but where they took it and what became of it he did not know. Eustachius, in 1564, dis- covered in the horse the thoracic duct, which he called vena alba thoracica, the white vein of the chest, not knowing its use. Wes- lingius, in 1649, found that the chyle vessels or lacteals of Aselius, termin- ated in the thoracic duct. By the labors of Monro, Hunter, with others, and especially Mascagni, the lymphatic vessels have been demonstrated as extending to almost every part of the body, the only parts in which they have not been seen are the brain, spinal marrow, ball of the eye, and placenta. The lymphatics have been considered as an appendage to the venous system. They resemble the veins in having the same structure, though their coats are more delicate. Like veins, they have numerous valves which give them a knotted appearance. Their currents are in the same di- rection, and terminate in veins. But they differ from veins in passing through glands, in being less tortuous, FIG. 18 represents the formation and course of the thoracic duct. a Termination of thoracic duct. 6 Its separation into two ducts, which again unite, c Lower end of duct, d Left azygos vein, e Right azygos. / Inter- costal veins entering right azygos. g h i j Correspond to numerous lacteals and lymphatics, which go to form the commencement of the thoracic duct. 122 LYMPHATIC GLANDS. and in having more numerous and perfect valves. These valves are generally semilunar, and arranged in pairs, though some are circular and do not close the canal entirely. The origin of the lymphatics is still involved in doubt, whether in the various tissues they commence by open mouths, or are continuous with one set of the arteries, and carry the serous portion of the blood, or whether they begin by a fine net-work of vessels. Let their microscopi- cal origin be what it may, it is well ascertained that the lymphatics come from nearly every portion of the body, while the lacteals spring exclusively from the interior of the intestinal tube, and especially its upper part. The former carry lymph, the worn-out material of the body; the latter, the lacteals, convey chyle, the fresh mate- rial formed by the process of digestion. Both sets of vessels, after passing through the various lymphatic glands, ulti- mately meet and converge to a point upon the second lum- bar vertebras, behind the aorta, and below the diaphragm, called the receptaculum chylL This receptacle of the chyle forms the commencement of, and is continuous with the thoracic duct, (Fig. 18,) a tube extending up the thorax between the aorta and vena azygos to the fourth dorsal vertebras, where it inclines obliquely to the left, behind the oesophagus and aorta, and inside of left subclavian artery, to the seventh cervical vertebra, from which it arches downward and outwards to the junc- tion of the internal jugular and left subclavian veins, at which angle it enters, protected by a pair of valves which prevent regurgitation. This tube receives the lacteals and the lymphatics belonging to the lower extremities, abdo- men, left half of the chest, left side of the head and neck, and the left upper extremity. The lymphatics of the right side of the head, right neck, right upper extremity, and right lung, meet, and enter the venous system on the right side by a second tube, at the junction of the right subcla- vian and internal jugular. The lymphatics are endowed with the properties of con- THE CUTANEOUS TISSUE. 123 tractility, elasticity, and extensibility, which are no doubt employed in their function of circulating the lymph, but this point is by no means yet satisfactorily settled. CHAPTER VI. T.HE CUTANEOUS TISSUE. ANALYSIS. IMPORTANCE, EXTENT, FORM, STRUCTURE, FUNCTIONS AND RELATION!. THIS tissue, especially its external portion, has received the names of dermoid, tegumentary, compound villous, or follicular membranes. Its importance may be estimated from its early development, vast extent, complexity of structure, variety of function, diversity of relations, and number of diseases. In the language of M. Beclard, this tissue is the " most universally extended in the animal kingdom; it is the first which is distinct and figured in the embryo; it is on it and by it the rest of the body is formed; and it con- tains the most essential functions, is often changed by disease, is the part on which all foreign substances produce impressions, and most therapeutic agents are applied." The extent of this element is commensurate with the whole external and internal surface of the body, wherever exposed to the contact of foreign substances. Its form has been compared to two canals, the one wide and external, the other narrow and internal, and the two continuous, the intervening space being occupied by the rest of the body. From this peculiarity of form, it consists of two great divisions. 1st. The skin and its appendages, forming the outer canal or external surface. 2d. The mucous membrane, forming the inner canal or internal surface. 't 124 SKIN AND ITS APPENDAGES. Though these two divisions present striking differences at first sight, yet they are so closely allied in structure, being regarded as essentially the same, that we shall ex- amine both as belonging to the same tissue. The skin can be traced as gradually sliding into, and becoming insensibly lost in the mucous membrane at all the natural apertures, as the mouth, anus, prepuce, labia, &c., showing the continuity of the two divisions ; and their identity is further established by their being convertible the one into the other. For instance, in the axillee, nates and other parts, where opposing surfaces of the skin come in contact and are not kept clean, the skin will become moist and soft, and present all the appearances of mucous mem- brane. On the other hand, mucous membrane, as in pro- lapsus of the rectum and vagina, by being exposed becomes dry, and assumes all the peculiar characters of skin. SKIN AND ITS APPENDAGES. The skin, (cutis, fopjta,) as already remarked, covers the whole external surface of the body, and according to the prize essay of Mr. Wheelock, measures in extent 2,500 inches. Its color varies from white to black, having all the inter- mediate shades depending on the different races of man- kind, and the difference in climate, age and exposure. Its density also varies, being thicker in the black than the white, and much more dense in some parts of the body than others, as in the palm of the hand and sole of the foot. It has two surfaces, the one free and exposed to external bodies, the other adherent to parts beneath by cel- lular tissue, and in the scalp and neck, closely connected with muscular structure, as over the occipito-frontalis and pla- tyma myoides. The free surface presents a variety of ob- jects of study, as inequalities of elevation and depression, folds and wrinkles, openings or pores, and various grades of softness and moisture, all of which will be more particular- ly noticed in the account of its structure. The adhering sur- face, by its loose cellular tissue, generally admits of free motion between the skin and adjacent parts. SKIN AND ITS APPENDAGES. 125 FIG. 19. The structure of the skin consists of three membranes — the cutis vera, rete mucosum, and cuticle. The cutis-vera, or true skin, is the innermost layer of the three. It is the chief mem- brane; is the thickest and strongest, and is regarded as the basis to the other two. Ac- cording to M. M. Beclard and Bayle, it is composed of cel- lulo-fibrous structure, in the form of an areolar web, more or less compact — that is, its cellular fibres, more or less interwoven with the fibrous, form a firm, compact mem- brane, varying in thickness from one-quarter of a line to one line and a half. Its thickness in the trunk is greater behind than before ; in the limbs greater externally than internally; it is remark- ably dense in the palms of the hands and soles of the feet, and particularly thin in the eye-lids,, mammse, scrotum and penis. We find the cellular and fibrous tissue varying in their relative proportions in different parts, and in accord- ance with the amount of motion and resistance to press- ure; the cellular predominating where freedom of motion is required, as in the axillae, while the ligamentous or fibrous is most abundant where there is greatest pressure, as in the plantar and palmar regions; and it is in conse- quence of this combination of the cellular and ligamentous tissue in the cutis-vera, that we find it possessed of the FIG. 19 represents the structure of the skin, a Epiderma, or cuticle, b Rete-mucosum. c Papillary clumps, quadrilateral in shape, composed of coni- cal papillae, and seen in the palm of the hand and sole of the foot, d Deep layer of derma, the corium. e Adipose cells. / Sudoriparous gland, with its spiral duct, g Sudoriparous gland, with a straighter duct, as seen in the scalp. h Two hairs from the scalp, enclosed in their follicles, i A pair of sebi-parous glands, opening by short ducts into the follicle of the hair. 126 SKIN AND ITS APPENDAGES. properties of flexibility, elasticity, and retractility. It also possesses considerable contractility, as seen in what is called the goose flesh, and in the scrotum, nipples, &c., and which seems to depend upon some reddish fibres, seen im- mediately beneath the dermoid tissue, having a contractile property and resembling involuntary muscle. The cutis-vera contains an immense number of blood ves- sels, nerves and lymphatics, which ramify through its sub- stance and appear upon its surface, and by some these are considered a distinct layer, under the name of the vascular retiform layer and the papillae, though not generally regarded as a distinct and separate structure. The external surface of the cutis-vera has numerous elevations or pro- jections, called papillae, which are very distinct on the extremities of the fingers and toes, and on the palms of the hands and soles of the feet. On the fingers these pa- pillae present the form of arched or concentric rows. These rows are separated by longitudinal and transverse fissures, which it is said give passage to the perspiratory ducts. The microscope reveals the papillae to consist of blood vessels and nerves, connected by cellular tissue, and ter- minating in loops. The nerves are seen without neuri- lemma, and the blood vessels, according to Beclard, have an erectile disposition. These papillae, wherever situated, are the seat of sensibility, and those upon the ends of the fingers, called tactile papillae, are the especial agents of the sense of touch. Though the nerves of the papillae have been said to terminate in loops, yet it is proper to say that some most respectable anatomists assert that they be- come so soft and fine that it cannot be determined whether they end in loops, plexuses or soft bulbs. The organic element of the cutis vera is principally gelatin. The rete-mucosum is the next layer in order, and covers the outer or papillary surface of the cutis. It is a very soft substance, and can be raised in a distinct layer, though with difficulty, after maceration. M. Galtier makes it to consist of as many as four separate laminae, the middle one being the seat of color. The most recent micro- SKIN AND ITS APPENDAGES. 127 ecopic observations, however, seem to regard the rete- mucosum as forming the internal layer of the cuticle, and being the fresh secreted substance from the cutis vera, which gradually hardens into the cuticle as it approaches the surface. Henle has found it to consist of small oval cells, containing a nucleus which became hardened, flat- tened, and ultimately changed into the scales of the cuticle. The coloring matter is also found to be produced by cells, called pigment cells — each containing a nucleus, and many granules. The choroid coat of the eye, it is said, exhib- its the pigment cells both distinctly and beautifully. The pigmentum iiigruni is sometimes absent in different parts of the body, as in the eyes of Albinos — who are thereby very sensitive to light. The Cuticle, Epidermis, or Scarf Skin, is the outermost or most external layer of the skin. It is easily separated by blisters, maceration, or putrefaction, and often comes off during scarlet fever; on raising it, it is seen to be con- nected by delicate filaments and hairs to the parts beneath. It consists of one homogeneous layer, destitute of cellu- lar tissue, vessels, and nerves. When separated, it pre- sents the character of the horny tissue — is hard, and varies greatly in thickness in different parts, according to press- ure; for example, it is thickest in the palms of the hands and soles of the feet ; it exactly adapts itself to all the inequalities, as the papillae and furrows upon the cutis vera, and from being without nerves and blood vessels, and consequently without sensation • and circulation, is admi- rably suited to protect the very delicate and sensitive sur- face of the cutis below. At the mouth, anus, and other natural apertures, it is continuous with the epithelium or cuticle of the mucous membrane. Under the microscope, the cuticle consists of several suc- cessions of small, hard, dry laminae or scales, each of which contains opaque spots of the original nucleus and cells, now flattened into scales, of an irregular form, overlapping each other at their edges, and constantly desquamating or falling off like particles of bran. It is nothing more than 128 SKIN AND ITS APPENDAGES. the secreted fluid from the cutis-vera, thrown out, it would seem, like varnish over the whole surface of the body, and then condensing and hardening into the scales just men- tioned. The process of formation is thus seen by the microscope. The capillaries of the cutis-vera throw out lymph, contain- ing numerous cell-germs ; these soon enlarge into cells, and closely apply themselves to the surface of the cutis. When this layer is completed a second layer forms beneath, and the first then becomes separated from the true skin, changes its form and consistence, becomes flat and hard, and, by evaporation, dry and firm, and finally falls off in scales ; and this succession of changes, from the primitive secreted nucleus of the cell germ, up to the dry flattened desquamating scale, is continually going on. The cuticle is flexible, elastic, and easily torn. Boiling water extracts some gelatine, renders it white, opaque, and deprives it of elasticity. When dry, its volume is di- minished, becomes firmer, slightly yellowish, and resists putrefaction for a long time, Fire causes it to burn like horn and emit a similar odor. The fixed alkalies resolve it into a soapy substance. Nitric acid turns it yellow almost immediately, and thickens, softens and reduces it to a pulp in twenty-four hours. The skin thus constituted of the cuticle, rete-mucosum, and cutis-vera, has its external surface moistened by two kinds of fluids — the one watery in its nature, called the perspiration — the other unctuous in its character, and known as the sebaceous. The perspiration, which, when augmented in quantity, becomes the sweat, is furnished by follicles called the sudo- riferous or sweat-glands, (Fig. 19 ;) they are found in all parts of the skin, are of a round form, and consist of a co3ca, ending in a spiral tube, the exhalent duct, which passes through the cutis, rete-mucosum, and cuticle, open- ing on the latter by a minute pore. In the axillae they are described as large, very distinct, and, by their reddish color, readily distinguished from the fatty grains adjoining them. SKIN AND ITS APPENDAGES. 129 The sebaceous or oily fluid comes from sebaceous glands. These, though not so numerous as the perspiratory, are nevertheless abundant in many parts of the skin, as the nose, face, arm-pits, arms, &c.; the palms of the hands and soles of the feet being destitute of them. They present a variety of form, from the simple sac-like follicle to the lobulated gland. In the scalp the lobes are clustered to- gether like a bunch of grapes ; and their ducts, which are straight, though sometimes spiral, besides perforating the skin, have one or more of them entering the hair follicle. (Fig. 19.) These ducts are lined by the involuted cuticle. The meibomian glands of the eye-lids, and the ceruminous glands of the ear, are also examples of sebaceous glands. The sebaceous glands are about the size of millet seed, of a yellow color, and most generally situated, as well as the perspiratory, in the subcutaneous cellular structure, though sometimes imbedded in the dermis itself. There is another set of glands belonging to the skin, called the odoriferous glands, (glandules odoriferse,) which are very particularly described by Dr. Homer, who seems to have given them more attention than any previous anatomist. He says they are well developed in the negro, and are found in the arm-pit, near the skin, and enveloped in cellular adipose structure. About three hundred of these glands were counted on a space the size of a Spanish dollar ; they are described as of a brown color, of varying size, from a line to two lines in length, and having a gran- ular surface, like the mammary and pancreatic glands. Their use is believed to be to furnish the odorous secretions of the body. The Functions of the skin are those of Sensation, Secre- tion, and Absorption. Sensation, as already stated, is either general or special — every part of the skin being supplied with nerves — so, in every part we find common sensibility, or tact, while spe- cial sensibility, or sense of touch, is very limited, confined almost exclusively to the tips of the fingers. By this func- tion the health and preservation of the body is particularly 9 130 SKIN AND ITS APPENDAGES. looked after ; it stands, as the faithful sentinel, on the out- posts of the system, giving immediate warning whenever an enemy is at hand, or an injury is suspected, whether by mechanical or chemical violence or the temperature of the atmosphere. This warning is by the sensation of pain. But this function is also intellectual, as, by the sense of touch, it is the medium of knowledge to the mind. '» The Secretion of the skin has been stated to be perspira- tory and sebaceous. By this function the properties of smoothness, softness, and pliability are imparted to the skin, and a large amount of superfluous matter thrown off, which, if retained, would destroy life. The amount of exhalation from the skin has been esti- mated by Sanctorius. It is stated that for thirty years he daily weighed his body, food, and excretions. His estimate was, that out of every eight pounds of nourishment, five passed off by the skin, leaving only three to be carried off by the lungs, kidneys and bowels. M. Seguin made the amount average about three pounds in the twenty-four hours* Twenty or thirty ounces of this exhalation, it is said, cannot accumulate in the system without causing disease; which is no doubt true. The perspiratory func- tion is also one of refrigeration, as by evaporation the body is cooled. Absorption, though at one period denied to the skin, is now fully established as one of its functions; for by the skin many articles of the materia medica are daily intro- duced into the system, and produce their effects with nearly the same certainty as when taken by the mouth. The Relations of the skin may be considered as Physical, Chemical, Organic, and Mental. The principal physical relation of the skin is atmos- pheric air, of a certain temperature and density. If the temperature be too low, the skin will become cold, torpid, and frozen, while the function of sensation will be ob- scured, benumbed, or entirely lost, and those of secretion and absorption completely checked or destroyed. On the other hand, if the temperature be too high, the violence SEIN AND ITS APPENDAGES. 131 of action, will result in the disturbance and destruction of its functions. The relation of the skin with the density of the atmos- phere is equally fixed and important During an ascent to the top of Mont Blanc, where the air is so much more rare, the cohesive property of the skin gives way for want of pressure ; a general relaxation occurs, and the blood, we are told, flows from the whole surface of the body. Too great density, on the other hand, would be equally de- structive. In regard to the Chemical relations of the skin, it is well known that if chemical agents be not applied in their due and proper proportion, they are violently destructive, at once disorganizing the skin, breaking up its whole texture, and, consequently, destroying all its functions. The skin, being an organ, and forming part of the body, becomes necessarily connected with, and more or less dependent on, every other part or organ ; and hence it has organic relations. The principal of these are with the mucous membrane and kidneys. When the functions of these organs are increased, those of the skin are dimin- ished, and vice versa. The Mental Relations of the skin, or those it has with the brain and nervous system, are equally striking. Every one has seen fear and grief contract the skin, and render it pale, cold, bloodless, benumbed, deprived both of sensa- tion and secretion. Anger and joy, on the contrary, dilate the skin, fill it with fluids, increase its color, excite all its functions, and, if in excess, will as certainly injure and derange them. Now these several relations constitute so many fixed and definite laws for the regulation of the skin's functions — obedience to which has the high reward of health and life; disobedience, the penalty of disease and death. The pen- alty is inflicted in a variety of ways, as in vices of confor- mation, congenital and acquired, accidental productions, as fistulas, abscesses, morbid secretions of the sebaceous folli- cles, having names according to the kind and consistency 132 APPENDAGES OF THE SKIN. of the fluid; a variety of tumors of varied size and charac- ter, as the steotoma, atheroma, meliceris, &c., or a fatty, a pulpy, and a honey-like tumor; and, finally, inflammation in all its various forms. APPENDAGES OP THE SKIN. The appendages of the skin consist of the hairs and nails, which are modifications of the cuticle. The hairs (Fig. 19) present differences, according to their situation, in length, fineness, delicacy, quantity, size, and color. They differ according to races, being long, fine, thick, and often curled, in the Caucasian and Malay, fine and thin in the American, short and coarse in the Mongolian, and crisped and woolly in the Ethio- pian. They vary also with age and sex, being finer in the young than in the old, and in the female than in the male. Each hair is composed of a bulb and stem. The bulb is simply a reflection of the skin, termed the follicle, con- taining a conical pulpy substance called the papilla. The follicle is ovoid in shape, and lined by the involuted cuticle ; it is embedded in the subcutaneous, adipose, and cellular structure, and is highly vascular and sensitive. The pa- pilla is the part of the bulb generating the hair; from its vessels, lymph is poured out containing cell germs; these grow into cells with nuclei, which elongate and become condensed into scales, overlapping each other, and form- ing the cortex or outer surface of the hair. The hair lengthens by fresh successive additions from the papilla, one beneath the other, constantly repeated, as long as it continues to grow. The interior of the hair, called the medulla, has its cells less condensed than the outer, and, on a transverse sec- tion, gives the appearance of a cell-tube. Hair can be split, and of itself separates into filaments. Pigment granules are found in the cells of the bulb, on which the color depends; and into the follicle the ducts of one or more of the sebaceous glands open and discharge APPENDAGES OF THE SKIN. 133 their fluids, which, it is said, lubricate the hair throughout its whole course. (See Fig. 19.) The formative force is very great in hair. It is quickly replaced when cut or destroyed, provided the bulb and papilla remain uninjured. Hair is entirely destitute of vitality, except at its root or bulb, where it is both vascular and sensitive, as seen in the disease called plica- polonica. The motions of the hair are referred to the action of sub- cutaneous muscles. This is very evident in the large hairs or prickles of the porcupine, and the feathers of the tail of the peafowl, where each is supplied with a distinct muscle for its elevation. Hair, like the cuticle, resists putrefaction for a long -time. Boiling resolves it into gelatin and coagulated albumen. According to Vauquelin, hair is composed of an animal matter which forms the base — a small quantity of a white concrete oil, a blackish oil, iron, oxide of manga- nese, carbonate of lime, silex, and sulphur. The Nails are the horny scales which cover the last phalanx of the fingers and toes. Each nail consists of a root, body, and free extremity. The root and borders are confined in a fold of the cutis, named the nail-follicle; the body rests upon the surface of the cutis, called the matrix, which is very vascular, and appears red; while the white portion, just at the root, is styled the lunula. The nail grows in a manner similar to the cuticle. The nail follicle and matrix contain papillae, that secrete the fluid or lymph in which are found cell-germs. These, like those of the hair, become compressed, dry, flat- tened and hardened into nail : those at the root elongating and adding to the length; those at the borders forming the breadth; while those in the matrix, or centre, increase the thickness. The nails protect and form a firm support to the tactile papillae or organs of touch. They are also instruments of prehension. 134 THE MUCOUS MEMBRANE. THE MUCOUS MEMBRANE. This constitutes the second division of the Cutaneous Sys- tem. It lines the whole interior of the surface of the body, having communication with the exterior world. It is consequently coextensive with the digestive, pulmonary, urinary, and genital organs. It is continuous, as before stated, with the skin. Its color varies from a pale rose to a beautiful red. Its density also varies, being thinner in the urethra and genital organs than in the intestines. Its tenacity is so slight, it tears easily in the attempt to raise it. Like the skin, it has two surfaces, the one free, the other adherent. The free surface presents valvulee, folds and wrinkles, cavities or depressions, and papillary and villous projections. The adhering surface is covered by a fibro cellular tissue, which gives the mucous membrane its solidity. It has two principal divisions. 1st. The gastro-pulmonary. 2d. The genito urinary. The first division lines the mouth, where it is continuous with the skin of the lips, and successively the pharynx, oesophagus, stomach, and intestines, to the anus, where it again runs into the skin. In this route it sends off numer- ous prolongations to all the excretory ducts of the glands, communicating with the alimentary canal, as the salivary glands, tonsils, liver and pancreas. It extends to the nose under the name of pituitary membrane, lining it and the different sinuses. Through the nasal and lachrymal duct it reaches the eye, covering the interior of the eyelids, and the globe of the eye. From the back part of the mouth we follow it in one direction through the Eustachian tube, into the cavity of the tympanum, and the mastoid cells, by another route we trace it into the larynx trachea, bronchi, and all .their ramifications in the lungs. The 2d division or genito urinary, beginning at the glans penis, is found lining the urethra, bladder, ureters, infundi- bulum, and even calyces of kidneys, while in the female it also covers the labia, clitoris, and vagina. THE MUCOUS MEMBRANE. 135 The mucous membrane presents different appearances in the different organs it traverses. It is disposed in longitu- dinal folds, is thick and loosely attached to the muscular coat in the oesophagus. It presents the form of plaits or rugae in the stomach, and of valvulaa conniventes in the upper intestines. The structure of the mucous membrane is very analogous to that of the skin, and like it, consists of three membranes, an epithelium, a proper mucous and a fibrous coat. The epithelium corresponds with the cuticle, and consists of nuclei, vesicles, and scales. It has, until very recently, been considered as extending inwardly only to the cardiac ori- fice of the stomach, but by the microscope it now seems to be satisfactorily established as covering the whole extent of the mucous surface wherever found. The epithelium presents a variety of forms in different situations. In the mouth (Fig. 20) it assumes the shape of laminae, the nuclei or cytoblasts forming the deepest layer, then upon these are the cells, and upon these again the topmost layer of polygonal scales, which become thin and flattened, and constitute the highest stage of development from the cell germ or nucleus. The nuclei, cells and scales are connected by a glutinous substance, in which are found opaque gran- ules. The scales are constantly exfoliating, and give place to the deeper layer, which in their turn give way to others, and so in perpetual succession, there is a perpetual waste and supply. In the stomach and intestines, the epithelium (Fig. 21) has the columnar or cylindrical shape, the apices of the columns resting on the papillary coat, while the bases, by their approximation, form the free surface. Each column has its nuclei, cells and scales, and is produced in the same way as the laminated epithelium, and also undergoing the constant waste and supply. FIG. 20. Epithelium scales from inside of the mouth. 136 THE MUCOUS MEMBRANE. FIG. 21. The columnar form of epithelium is also found in all the glandular ducts, whose bases are often surmounted with cilite, (Fig. 22,) whose motions are directed towards the FIG. 22. outlets of the canals they line. The second coat, the proper mu- cous, called also the papillary or basement membrane, resembles the papillary layer of the skin, and is a membrane apparently without texture. Its sur- face presents different aspects at different points. In the stomach it forms cells or alveoli, into which the follicles open. In the intestines it presents numerous pro- jecting points, having a velvety appearance and called villi, while in the large intestines it again, as in the stomach, assumes the shape of cells. This coat is exceed- ingly soft and spongy, easily destroyed either by mechani- cal violence or the action of acids, which reduces it to a pulpy state. The fibrous layer, called also the sub-mucous and nervous, forms the third layer of mucous membrane. It corresponds to the corium of the skin, in giving support and strength to the mucous layer, and contains numerous capillary vessels, nerves and absorbents. It has just been stated that the mucous membrane has upon its papillary surface numerous conical projections, FIG. 21 represents cylinders of the Intestinal Epithelium. 1 Cylinders from cardiac region of the human stomach. 2 Cylinders from jejunum. 3 Cylinders seen from their free extremity. 4 Cylinders as seen in a transverse section of a villous. FIG. 22, Ciliated Epithelium. 6 Cilia upon the top of a epithelium. THE MUCOUS MEMBRANE. 137 called villi from their velvety appearance, or their resem- blance to the down of an unripe peach. Each villus consists of blood vessels, nerves and absorb- ents bound together by cellular tissue, and not only cov- ered by epithelium, but also, it is said, by an additional fine membrane. These villi give origin to the lacteals by fine branches, which, it is now found, do not have open orifices upon their surface as formerly believed, but between the capillary vessels at the extremity of each villus, while chylous absorption is going on, are seen cells containing an opalescent fluid. These cells disappear almost entirely, it is said, when the chyle has left the intestine; the lac- teals empty themselves, and the villi become flaccid. These cells are regarded as the special agents for select- ing the nutrient matter and handing it over to the lacteals ; they have a short life, and are constantly being renewed. Another element of mucous membrane is found in the follicles and glands scattered throughout its whole extent. The simple follicles of Leiberkuhn exist in immense numbers every where upon the mucous surface. They con- sist simply of depressions of the mucous surface, forming small pouches, whose orifices are not visible to the naked eye, but which are found to have eight or ten times the diameter of the red globules of blood. Professor Homer has estimated the number of these fol- licles to be about 25,000 to the square inch, and between forty and fifty millions to the whole alimentary canal. Their use is to supply the principal part of the mucous fluid. The glands are simply compound cryptce or folli- cles, having different forms and names, in different parts of the mucous membrane. At the mouth of the Eustachian tube, the simple follicles are collected in a body of somewhat oval form and almond size, called the tonsil. In the oesophagus these follicles are situated in the sub-mucous tissue, and lobulated, communi- cating with the surface by a long excretory duct. In the stomach the glands are seen in the shape of long tubes, situated perpendicularly, side by side, and, at their 138 THE MUCOUS MEMBRANE. terminations, dilated into small pouches,, having a clustered appearance. These are supposed to secrete the gastric fluid. In the duodenum is another set of glands called, after their discoverer, Brunner's Glands. (Fig. 24.) FlG- 24- They are small, granular, and flattened, and compared to the pancreas and salivary glands; each granule consist- ing of minute lohules or cells, all of which open upon the surface by a common duct. In the lower part of the ileum are the glandulae agminata3,or Peyer's glands. (Fig. 25.) They are found most abundant about the junction of the ile- um with the colon, and op- posite the attachment of the mesentery. They are Collected in numerous small circular patches, sur- rounded by the simple fol- licles. Each is simply a closed sac, having no ex- cretory duct, as far as ob- servation has gone, and, when ruptured, is found to contain mucus and small cells. Their use is not known. It is thought by some that ulceration of Peyer's glands constitutes the essential FIG. 23 represents a portion of the mucous membrane of the stomach, show- ing the pits upon its surface, and where the tubes from the gastric glands enter. FIG. 24 represents a portion of one of Brunner's glands from the human duodenum— magnified 65 diameters. FIG. 25 represents a portion of one of the patches of Peyer's glands at the termination of the ileum. THE MUCOUS MEMBRANE. 139 element in typhoid fever, while others regard such lesion simply a result of the latter. There is another set of glands "belonging to the mucous membrane, called the Grlandulge Solitarige, or Solitary Glands. These are of two kinds — those having excretory ducts, or openings, and those without. The first are found in the large intestine, being most abundant in the coecum. The second are seen in the small intestine, in the form of small circular patches, surrounded by a wreath of simple follicles, and, when opened, present a small, saccular, flat- tened cavity, holding mucus. Dr. Homer, who has paid much attention to the investi- gation of the minute anatomy of the mucous membrane, seems to think, from his observations during the chol- era, and minute injections of this membrane, that it "con- sists almost entirely of a cribriform intertexture of veins ;" and, in death, these veins being empty, are soft and spongy, and give the velvety appearance of ordinary descriptions. The arteries are described as few in number, and situated beneath the venous intertexture, and much smaller than the corresponding veins. The meshes in this venous inter- texture are very minute, and are considered as the simple follicles of Lieberkuhn, resting upon the arterio-venous layer and cellular structure below as their basis. Dr. Homer is led to believe, from this anatomical arrangement of the mucous membrane, that the functions of these follicles are rather for absorption than, as generally supposed, for secre- tion. As the Fallopian tube, by a vascular turgescence, erects itself and grasps the ovum, in like manner, says the doctor, " as these intestinal follicles are formed in the midst of veins, their orifices only become erect and patulous by the distension of those veins, and cannot be well seen by the eye alone, unless an injection has fully succeeded. But the erection of these veins, during digestion, puts the folli- cles in a similar condition; there is, therefore, some ground of inference that the act of the Fallopian tube in conveying a germ, and of a follicle in conveying into the thickness of an intestine congenial matter, may be analogous." 140 THE MUCOUS MEMBRANE. Again, this same anatomist universally found the sur- faces of the villi polished, and not presenting any foramina, while many of the follicles were found passing obliquely into their bases. In a word, the gastro-enteric follicles, situated in the venous intertexture above described, and considered as identical with its meshes, are regarded as the absorbing agents of the chyle, which conduct it into the lacteals. The functions of the mucous membrane are, like those of the skin, sensation, secretion, and absorption. Besides the common sensation of the whole membrane, and the special sense of taste as belonging to it, and seated in the tongue, the feelings or appetites of hunger and thirst are also re- ferred to this membrane. Its secretions are those of serum and mucus, &c., and it absorbs, as already stated, the chyle with other matters. The relations of the mucous membrane are as fixed as those of the skin, and are, chiefly the physical, chemical, and organic. The principal physical relations are those it has with food and water. It is well known that our food and drink enter the sys- tem mainly through this structure, and if we attempt, in the healthy state of this membrane, to substitute any thing else in place of the natural stimuli, there will certainly be more or less lesion and disturbance of its functions. For instance, if we swallow poison, in place of food, there is the greatest danger not only of disturbance, but of com- plete destruction to both structure and function, by the most rapidly violent and destructive inflammation. And this example further shows the chemical relations of this membrane to be equally fixed, and necessary to be observed, for the preservation of its integrity. Its organic relations are most important, both in health and disease, as it sympathizes with, and is the channel of intercourse to every other part and organ of the body. Now, these several relations, as in the case of the skin, constitute so many fixed laws — obedience to which, we THE MUSCULAR TISSUE. 141 equally find, has the reward of health and life, and diso- bedience the penalty of disease and death. The penalties refer to the pathological state of this membrane, the prin- cipal of which consist in — Malformations , congenital or acquired, as seen in oblite- ration of the rectum. Displacements , as in prolapsus of the vagina. Stricture, as in the urethra. Tumor, as polypi of the nose and uterus. Vegetations. New Formations, as cartilage, bone, hair, &c. Discharges, as serum, mucus, blood. Inflammation, with all its terminations in suppuration, nlceration, and gangrene. The appendages of the mucous membrane are the Teeth ; which see in another part of the work. CHAPTER VII. THE MUSCULAR TISSUE. ANALYSIS. DEFINITION, IMPORTANCE, DIVISION, FORM, COLOR, SIZE, CONSISTENCE, COURSE, NUMBER, ATTACHMENTS, NOMENCLATURE, STRUCTURE, FUNCTIONS, DEVELOPMENT. Muscle (from /wvwv, a muscle, or ^tuj, a mouse,) is the ac- tive organ of motion in the different parts of the body. In familiar language, it is called the flesh, and, by its pro- perty of contraction, is connected with many of the most important functions. The importance of this tissue may be estimated, when we consider that the functions of diges- tion, respiration, circulation, locomotion, speech, and ex- pression, are all dependent upon it. Muscles, as we shall presently see, consist of bundles, mostly of reddish fibres, of variable size and strength, and have a head, body, and tail, or, in more anatomical language, an origin, course, 142 THE MUSCULAR TISSUE. and insertion. The muscles, collectively, form the mus- cular system. They have been arranged under two grand divisions. 1st. The Voluntary, or all those subject to the control of the will. 2d. The Involuntary, or those over which the will has no influence. A third division is made, called the Mixed class of Muscles, which is a compound of the other two, over which the will has only partial control, as seen in most of the Sphincters. The first class are by far the most numerous, and situ- ated chiefly upon the face and extremities — composing the greater bulk of the organs of relation. The second class belong to the organs of nutrition, comprising the stomach, intestines, heart, &c. Muscles are either arranged in pairs or are symmetrical. The first are found upon either side of the median line of the body, perfectly distinct, wide apart, and each exactly alike, as upon the limbs; or they may approach so close along the middle line as to touch 6ne another, but still preserve their perfect distinctness of separation. The symmetrical muscles are situated pre- cisely upon the median line, and consist in two equal and similar halves. Muscles, according to their form, are distinguished into the long, the flat or wide, and the short. The long mus- cles are generally placed upon the limbs, to the beauty and conformation of which they very much contribute. The wide are mostly situated upon the parietes of cavi- ties, as those of the chest and abdomen, and "serve to protect the internal organs, aid their functions, and move the body or the limbs, as the one or the other is the fixed point." The wide muscles, generally, are not very thick — in some places resembling a thin membrane, as the broad muscle of the neck, so conspicuous in the horse, which that animal uses as a fly-brusher. The short muscles are commonly met with in parts where there is a limited extent of motion and great power required, as in the movements of the lower jaw and the thumb. The situa- tion of muscles is either superficial or deep. The superfi- THE MUSCULAR TISSUE. 143 cial are immediately beneath the skin, and arranged side by side, while the deep surround the bones and occupy the interior of cavities. The color of muscles is red, varying in intensity in dif- ferent muscles, and in different individuals. The red color, however, only«applies to the voluntary muscles; for the involuntary, as those of the intestinal tube, bladder, &c., are exceedingly pale, and, in some of the lower animals, the whole muscular system is completely colorless. The color is thought to be independent of the blood circulating in their vessels; and the bright red of those muscles subject to the control of the will, is an invariable evidence of both vigor and activity. The consistence of muscles varies in different individuals, and in the same individual at different times, according as the system is healthy or diseased. In some they are soft and easily torn; in others they are not only firm and resisting, but for some time after death remain rigid. Their size also varies, from the extremely delicate mus^ cles of the face, to the powerful glutens maximus of the hip. The course or direction of muscles is essential to a correct knowledge of their several actions, and of the proper method of reducing dislocations. Every muscle has an axis or middle line, in which its fibres centre or take effect, and should, says M. Cruveilhier, be studied with special reference to the axis of the limb, or lever of which they are the moving power. The number of muscles varies in different animals, and in proportion to the variety, and the extent of motion, each has to perform. The number in man is not agreed upon by anatomists. Prof. Chausier makes 368, Paxton 52T, w.hile others make 450 ; 400 is considered a fair average number. The cause of this disagreement is owing to the fact that some muscles are divided into two or more, while others think they should be considered but as one. The names given to muscles, are derived from a variety of circumstances, as their uses, attachment, direction, figure, composition, size, &c. Examples of names from uses may 144 THE MUSCULAR TISSUE. be found in the flexors, extensors, and rotators of the limbs; from attachment in the muscles, connected with the styloid process of the temporal bone, the hyoid bone, the tongue, and pharynx, and named the stylo-hyoideus, stylo-glossus, and stylo-pharyngeus; from direction in the straight mus- cles of the thigh, the oblique of the neck, and transverse of the abdomen and perineum; how figure in the rhomboi- dei or four-sided muscles of the back, and the scaleni or unequal-sided triangular muscles of the neck ; from compo- sition in the biceps, triceps, perforans, &c., as they are composed of two heads, three heads, or are perforated. The attachment of muscles is various. They are at- tached to the skin, as in the platysma myoides of the neck, to other muscles as in the angles of the mouth, to cartila- ges as in the chest and larynx, to aponeuroses, to tendons, and through these to the periosteum and bones. The at- tachment of muscles to the most fixed point is called their origin, while that to the most movable is regarded as their insertion. The structure of muscles consists of bundles of fibres called fasciculi, enclosed in a cellular membrane or sheath. Each fasciculus is composed of still smaller bundles, and these again of single and more minute filaments; and here the microscope is brought FIG. 26. in to determine what is called the ultimate fibre. (Fig. 26.) This ultimate fibre is found to consist of a num- ber of still smaller fibres called the ultimate fibrils, which are enclosed in a very delicate sheath termed the myolemma or sar co-lemma. FIG. 26 represents the Muscular Fibre of animal and organic life — a mus- cular fibre of animal life enclosed in its sheath, the myolemma, and showing the transverse striae ; fe Ultimate fibril of the same ; c A more highly mag- nified Tiew of Fig. a ; d Muscular fibre of organic life, from the urinary blad- der, magnified 600 diameters ; e Muscular fibre of organic life, from the stomach. THE MUSCULAR TISSUE. 145 This sheath is considered quite distinct from the cellular tissue surrounding a fasciculus of fibres, and is perfectly transparent The microscope reveals t^wo kinds of ultimate fibres, one belonging to the muscular system of animal life, or voluntary muscles, the other to that of organic life or the involuntary class. The fibre of animal life is known by being marked with transverse striae, by having the fibril- lae beaded or knotted, and presenting a varicose appear- ance. The fibre of organic life has no transverse striae, and is much smaller than the fibre of animal life. It pre- sents swellings at different points, and this is considered as one of its most prominent characteristics. The form of the ultimate fibre, according to Mr. Bowman, is polygonal. When the fibrils are separately examined, they are found to present spaces of alternate dark and light color. The size of these ultimate fibrils, according to Wagner, is nearly the same in all the vertebrata, from the 1-8856 to 1-11076 of an inch in diameter. The diameter of the primitive fas- ciculi is stated to be very variable in the different classes and genera, and even in the same animal and same muscle. The size is greater in the male than in the female, the average diameter, as given by Mr. Bowman, is about 1-400. The microscopic observations of Mr. Bowman also show that there exist in the substance of the ultimate fibre, small discs, either circular or oval, frequently concave on one or both surfaces, and having, near the centre, one, two, or three minute granules or dots. These are found to be connected with, and distributed in nearly equal numbers between, the fibrils ; and these granules or corpuscles are regarded as the nuclei, which being developed into the nucleated cell, constitute the origin whence the muscular fibre is formed. The corpuscles can be seen by treating muscle with some of the milder acids, as the citric. Blood vessels and nerves enter abundantly into the structure of muscles. Muscles possess the vital property of contractility, by which they can contract and shorten themselves, and which, as already stated, they take part in a great variety 10 146 THE MUSCULAR TISSUE. of functions, and form the especial and active agent in locomotion. Fibrin is the chemical element constituting the great mass of muscle, and peculiarly adapted to contraction. The chemical composition of muscle is thus given by Ber- zelius : Water, TY.lf Alcohol, ext with salts, 1.80 Fibrin, 15.80 Watery, . fV 1.05 Albumen with color- Phosphate of lime with ing matter, 2.20 albumen, 0.08 The different varieties of muscular contraction are those of force or intensity, duration, velocity, and extent ; and examples of each variety may be seen in the several mus- cles of the human body. The most rapid movements, ac- cording to Haller, are to be found in the muscles of the voice, since the pronunciation of a single letter can be exe- cuted in the 1-3000 part of a minute. From experiments on the bodies of executed crimi- nals, Mr. Nysten found that the muscles lost their contrac- tility in the following order — first, the left ventricle of the heart, next the intestinal canal in 45 or 55 minutes, the urinary bladder in nearly the same time; in one hour the right ventricle, in one hour and a half the oesophagus, the voluntary muscles a little later, and the last of all, the au- ricles of the heart, particularly the right, which, it is said, Tinder the influence of galvanism, contracted 16J hours after death. Muscles also have sensibility, and are further en- dowed with an especial sense, called the muscular sense, by which the precise state of the muscles is made known. The development of the muscular system takes place from the germinal membrane, which is made to consist of three layers, an external or serous, an internal or mucous, and a middle or vascular. The voluntary muscles or those of animal life, found in the trunk and limbs, are developed from the serous layer, while the involuntary or those of organic life, comprising the intestines, bladder and inter- nal organs of generation, are developed from the mucous. TENDONS. The vascular layer develops the heart, which, though in- voluntary, is found to contain the transverse striae of the muscles of animal life. Tendons. — Tendons form the extremities of muscles, as a general rule, though we sometimes find them, as in digas- tric muscles, occupying the centre. FIG. 27. They are easily distinguished by their beautifully white and shining , appearance, and though seemingly continuous with the muscular fibre, and at one time considered as such, yet by maceration and boiling they can be separated. The structure of tendon is cellular, condensed, and modified into the funicular or cord- like, and the membraniform shape- Its chemical element is gelatin. Its fibres run longitudinally,, being connected by lateral fibrils, and ad- hering with the greatest tenacity to muscle. They have so little ex- tensibility, that it is believed they will break sooner than stretch. They have no contractility, nor elasticity. Their sensibility in the healthy state is obscure, while in the diseased it becomes very evident. In health, tendons have no red blood circulating in them, while in inflamma- tion the red globules become very manifest. No nerves can be traced passing into this tissue. FIG. 27 represents the attachment of tendon to muscular fibre. 148 THE FIBROUS TISSUE. -a CHAPTER VIII. THE FIBROUS TISSUE.' ANALYSIS. 3YNONYMES, DEFINITION, DIVISION, FORM, PROPERTIES, STRUCTURE, FUNCTIONS, AND RELATIONS. THE fibrous tissue lias received the several names of albu- gineous, tendinous, aponeurotic, ligamentous and dermoid tissue. It comprises an assemblage of organs, having various forms, serving different purposes, but all having the common character of being composed of distinct fibres, both firm and strong. Its principal divisions are, 1. Ligament. 2. Tendon. 3. Fibrous envelopes, &c. 4. Fibro cartilaginous bodies. These several varieties do not form one continuous and connected whole, though Bichat and others have endeav- ored to fix a common centre. Bichat takes the periosteum as this centre, others the membranes of the brain, and others the aponeuroses. The fibrous system is distinguished by its brilliant white color, great strength, so great as to have resisted effectu- ally horse power, when applied to the extremities. It has little extensibility, breaking before it will stretch, very lit- tle elasticity, but is endowed with great flexibility, and resists putrefaction for a long time. By desiccation it becomes "somewhat elastic, transparent, of a yellowish red color, and almost homogeneous, but by submitting it to the action of water, it recovers all its original characters." . v " Boiling reduces it to a soft, gelatinous condition, though at first, it is said, contracting it and making it more solid and elastic. The mineral acids reduce it to a pulpy state, and if concentrated, entirely dissolve it. Alkalies, it is said, loosen its texture, separate its fibres, and cause them to assume a diversity of colors. THE FIBROUS TISSUE. 149 FIG. 2& The structure of this tissue is essentially fibrous, that is, it consists of threads or fibres variously arranged in its different divisions; some being parallel, some wavy, some crossed, others mixed, and some so very compact as to appear homogeneous. In the fibrous tissue are distinguished two kinds of fibres, the white and yellow. The white (Fig. 28, A,) is described as presenting the form of " inelastic bands," of variable size, wavy in their direction, having numerous streaks lon- gitudinally. It is reduced to gelatin by boiling, and, un- der the action of acetic acid, is seen by the microscope to swell up, become transparent, and exhibit oval corpuscles, which latter are believed to be the formative nuclei of this element. This white fibre is very abundant in tendons, ligaments, fibrous membranes, aponeuroses, &c. The yellow fibre (Fig. 28, B,) presents the form of a cylin- der; readily separates from its fellows in the longitudinal direction; breaks abruptly and curls upon itself, as seen in the figure, and differs from the white, in that boiling has little or no effect upon it. Its elasticity is said to be pre- served for an almost unlimited period. From acetic acid having no effect upon it, it can always be distinguished from the white tissue. Various opinions have been enter- tained in reference to the ultimate structure of these fibres. Mascagni believed they were absorbent vessels, surrounded FIG. 28. A represents the white fibrous tissue from ligament, magnified 65 diameters. B shows the yellow fibrous tissue from the ligamentum nuchte. 150 -.7 LIGAMENTS. by a vascular web. Beclard considers them as condensed cellular tissue, since maceration softens and reduces them to this structure. Isenflam supposes them to be cellular filaments, containing gluten and albumen; while M. Chaus- isier thinks they are primitive and peculiar. The microscope lias measured the ultimate filaments into which the fas- ciculi are capable of being resolved, and determined it to be from the 1-30,000 to the 1-10,000 of an inch. The vital properties of the fibrous tissue, in the healthy state, are very obscure. It then evinces little or no sensibility, while in inflammation it is susceptible of the most acute pain, Its power of repair when injured or lost is considered to be very great. In the embryo, this tissue, like all other parts, is soft and mucus-like in its appearance. It is distinguished about three months after impregnation. In the infant it presents a pearly white appearance, is more extensible than in the adult, yields more readily and is less liable to break, The common functions of the fibrous system are mechanical, and will be noticed more particularly under its several divisions, which we shall now take up separately. LIGAMENTS. Sydesmology (awSeaftos, a ligament, xoyoj, discourse,) is the term applied to the study of the ligaments. Ligament (from ligare, to bind,) is so called because it ties the several bones together in the skeleton; the connection between any two constituting a joint, or articulation. Ligaments most distinctly represent the true character of the fibrous sys- tem. They are mostly situated at the extremities of all bones forming joints. Unfortunately, this term has also been applied to an entirely different structure, as to the se- rous membrane of the abdomen, whose reflections upon the liver, uterus, &c., are called the ligaments of these or- gans, simply from the fact of their keeping these parts in their natural positions, and not at all from the serous membrane being supposed to have any really fibrous struc- ture. The ligaments are very numerous, and get their LIGAMENTS. 151 names from a variety of circumstances, as from situa- tion, use, attachment, direction, resemblance to certain things, &c. Examples of situation are seen in the lat- eral ligaments; of use, in the capsular; of attachment, in the sacro-sciatic; of direction, in the crucial; and of resemblance, in the coracoid, trapezoid, &c. Ligaments may be arranged, according to the motion of the part in which they are found, into three divisions : 1. Articular, 2. Non-articular, 3. Mixed. All these divisions have their fibres arranged in such a way as to assume one of two forms — either that of bundles, called the funicular, or that of membrane, the membrani- form. The articular ligaments are the most important; they belong to the different joints, tie together different bones, where there is motion, and present both the funicular and membranous forms, as seen in the humeral and femoral articulation. Here the membrane is called the capsular ligament, which is a sheath surrounding the articulating bones, binding them together, and having its inner surface lined by synovial membrane. The funicular ligament has its fibres collected in a rope or cord, which may be internal to the capsule, as the ligamentum teres of the thigh joint, or external, as the lateral ligaments of other joints. All these ligaments have one of their faces corresponding with the synovial membrane, the other to the surrounding cel- lular tissue, except those within the capsule, which have an entire covering of synovial membrane. The non-articular ligaments are attached to different parts of the same bone, where there is no motion. They close notches, for the transmission of vessels and nerves, as the supra-orbital, or shut up foramina, for the attachment of muscles, as the obturator. Those closing notches are funicular; those shutting foramina are membranous; and both are without a synovial membrane. The mixed ligaments partake of the characters of the other two, in belonging to different bones, like the articular, and 152 ARTICULATION. being destitute of a synovial membrane, like the non- articular. These are found in the interosseous spaces; and the sacro-sciatic ligaments belong to this class. Besides ligament, there are other elements entering into the con- stitution of joints, as bone, cartilage, fibro-cartilage, and synovial membrane. Each of these will be noticed in its proper place. The different forms of articulation are arranged in three classes : 1. Diarthrosis, 2. Synarthrosis, 3. Amphiarthrosis. Diarthrosis (&a, through, apfyoi', a joint,) is a movable articulation, and constitutes the great number of the joints. There are three varieties of this articulation, according to the degree of motion — enarthrosis, arthrodia, and ging- lymus. Enarthrosis (sv, in, opflpov, a joint,) has the greatest range of motion of all the joints; it is called the ball and socket- joint, from the form of the bones, and the manner of their connection, as the hip and shoulder. Arthrodia is an artic- ulation having a more limited range of motion, as the clavicle, ribs, articular processes of the vertebrae, radius and ulna, carpus, tarsus, &c. Ginglymus (rtyy^oj, a hinge,) is a hinge-like joint, where the motion is backwards and for- wardS; flexion and extension, as seen at the elbow, knee, and ankle. A variety of the hinge-joint, called the rotatory, is fbund between the radius and ulna. The synarthrosis (ow, together, apflpov, a joint,) is the articulation without motion, where the bones are immovably connected together. There are four varieties of this joint : 1. TheSutura. 3. Schindylesis. 2. Harmonia. 4. Gomphosis. The suture has several varieties; it is serrated when the .bones come together and interlock, by processes at their margins, resembling the teeth of a saw, as in the coronal, .sagittal, and lambdoidal sutures of the cranium. It is called -squamous (squama, a scale,) when the bones overlap, as the temporal and parietal at the side of the head. Har- monia, (op«, to adapt,) is a species of suture, where the con- TENDONS. 153 tiguous surfaces of bones come together, by rather a smooth surface and without any serration, as in the nasal, superior maxillary, and palate bones. Schindylesis (40*8*4** a fis- sure,) is also a variety of suture, and consists of a fissure or gutter, by which one bone is received into another, as the vomer, the sphenoid, and ethmoid. Gomphosis (70^05, a nail,) is that species of articulation where the bone is fitted to another, after the manner of a nail that is driven in a board. The teeth are specimens of this variety. Am- phiarthrosis, (a^c, both, aP9ov, articulation,) as its name implies, partakes of the character of both the diarthrosis and synarthrosis; that is, it has a little of the motion of the former, and, like 'the latter, is without synovial mem- brane, as in the bones of the vertebrae. The union of the scapula, or shoulder-blade, to the trunk, by means of muscle, called syssarcosis, (i>cyiat, to grow,) in early life epiphy- ses, (frtt, upon, $u 4L . The cerebral surface of this process is concave, and deeply grooved for lodging the lateral sinus. The third or petrous portion, named from its stony hardness, is situated between the squamous and mastoid, and proceeds forwards and inwards into the base of the cranium. Its/orm is triangu- lar, with the base posterior, and presents three surfaces, one external or inferior, and two internal or cerebral. On the inferior surface are noticed the following points : first and most prominent, the styloid process, a long, slen- der projection, sometimes two inches in length, giving at- tachment to the three styloid muscles and two ligaments. Behind and at the root of this process, between it and FIG. 41 represents the cerebral surface of the Temporal Bone. 1 Squamous portion. 2 Mastoid. 3 Petrous portion. 4 Groove for the middle meningeal artery. 5 Edge of squamous suture. 6 Zygomatic process. 7 Digastric fossa. 8 Occipital groove. 9 Groove for lateral sinus. 10 Superior petrous sinus. 11 Opening of the carotid canal. 12 Internal auditory foramen. 13 Aqueduct of the vestibule. 14 Styloid process. 15 Stylo mastoid foramen. 16 Foramen caroticum. 17 Spine dividing the jugular vein from the eighth pair of nerves. 18 Vidian foramen. 19 Where the levator palati and ten- sor tympani muscles arise. BONES OF THE CRANIUM. 1ST the mastoid is the stylo-mastoid foramen, for transmitting the facial nerve, or portio dura of the seventh pair. This foramen is the lower aperture of the aqueduct of Fallopius. The styloid process is surrounded by a process at its root, very prominent anteriorly, called the vaginal, which separates the glenoid cavity from the carotid foramen, and foramen lacerum posterius. In front and obliquely to the inside of the styloid process is the foramen caroticum leading into a canal, the carotid canal, which is first vertical, and then proceeds forwards, inwards and upwards, and opens within the cranium, by the side of the body of the sphenoid bone. It gives passage to the carotid artery and branches of the sympathetic nerve. In front of the carotid foramen is a rough surface for the origin of the levator palati muscle. By the side of the styloid process is a vertical ridge, within and posterior to which is a deep cavity called the jugular fossa. This, with a corre- sponding one in the occipital bone, constitutes the foramen lacerum posterius, through which passes the eighth pair of nerves and the lateral sinus, the nerves being anterior and separated from the sinus, which is posterior, by the vertical or jugular spine. Upon this ridge is described the opening of the aqueduct of the cochlea. The angle between the squamous and petrous portions is occupied by the spinous process of the sphenoid bone. At this point there are two canals, the one above, the other below, separated by a thin plate of bone; the upper gives origin to the tensor tympani muscle, the lower is the bony part of the Eustachian tube, and both go to the tympanum. The cerebral surface of the petrous portion is divided by a sharp ridge, to which is at- tached the tentoriunr, into an anterior and posterior surface. On the anterior or superior surface is seen a depression for receiving the Gasserian ganglion of the fifth pair of nerves. Near this is a groove leading to an opening about the mid- dle of this surface, called the hiatus Fallopii, which leads to the aqueduct of Fallopius, and transmits the superior branch of the Vidian nerve. This surface is marked by an emi- nence for the superior semi-circular canal, and by depressions 188 BONES OP THE CKANIUM. for the convolutions of the brain. Its superior ridge con- tains a groove for lodging the superior petrosal sinus. The posterior surface has about its centre a large open- ing, the meatus auditorius internus, which gives passage to the seventh pair of nerves. It is directed outwards and somewhat forwards into a short canal, at whose termina- tion there is a transverse ridge dividing it into two parts. The inferior is cribriform and transmits the portio mollis or auditory nerve, while the superior is a single foramen, which leads to the aqueduct ofFallopius, and gives passage to the portio dura or the facial nerve. This aqueduct of Fallopius is a long canal passing outwards and downwards behind the tympanum and terminating in the stylo-mastoid foramen. Behind the meatus internus is a small orifice, the aqueduct of the vestibule. The base or exterior mar- gin of the petrous portion is rough, for the attachment of the cartilage of the ear, and at this point is seen the fora- men auditorium externum which leads into the auditory ca- nal, a tube about a half an inch long that takes a curved direction downwards,, inwards, and forwards, to the mem- bran a-tympani. This canal is composed chiefly of what is called the auditory process. The petrous bone also contains the organs of hearing, which will be examined in another place. The foramina are twelve in number, 10 special and 2 com- mon. The special are the external and internal auditory, the stylo-mastoid, the mastoid, the carotid, glenoidal, Eusta- chian, Vidian, aqueductus cochleae, and vestibuli. The com- mon are the anterior and posterior foramina lacera. The processes enumerated are six — the styloid, the mastoid, the auditory, the vaginal, the zygomatic, and the jugular. The structure of the temporal bone, in its squamous por- tion, is thin and mostly compact; the mastoid contains large cells, and the petrous is considered next in density to the teeth. Its development takes place by six points, viz : the squamous, mastoid, petrous, zygomatic, styloid, and auditory. The first osseous point is seen in the squamous about the BONES OF THE CKANIUM. 189 end of the second month; very soon afterward the petrous portion begins to ossify; in the fifth month the mastoid, and the last of all the styloid. The squamous, mastoid, and petrous portions become uni- ted during the first year. The styloid process is not con- nected with the petrous portion for several years after birth, and sometimes remains permanently separate. Occasion- ally it has been found to extend, by several pieces, to the hyoid bone, thus forming the hyoid arch. The tympanic ring becomes united to the squamous portion about the last month of foetal life. Other changes are observed in the after development of the temporal bone, as in the growth of the mastoid cells, the extension of the meatus auditorius externus, the enlargement of the glenoid fossa, and the filling up of the irregularities of the petrous portion. At birth three pieces compose the temporal bone, viz: the squamous and zygomatic, the mastoid and petrous, and the tympanic. Its articulations are with five bones. With the parietal by the superior border of the squamous ; with the sphenoid by the anterior, and the occipital by the posterior border; also with the malar at the zygomatic suture, and the lower jaw in the glenoid cavity. Ethmoid Bone. — (E^J, a sieve.) The situation of the ethmoid bone is in the large notch be- Fio 42 tween the orbitar plates of the fron- tal bone. It enters into the forma- tion of the nose, the orbit of the eye, and the anterior base of the cranium. It receives its name from its cribri- form or sieve-like appearance. Its form is cuboidal. Its surfaces are three, one superior or cerebral, and two lateral or orbital; there is also an inferior y anterior, and & posterior portion. FIG. 42, ^Ethmoid Bone, showing an upper and posterior view, a Nasal lamella. 6 Cellular portion or body, c Crista-Galli. d Cribriform plate, e Superior meatus. / Superior turbinated bone, g Middle turbinated bone. & Os-planum. i Surface for olfactory nerve. 190 BONES OF THE CRANIUM. The superior surface is the cribriform plate. It is of an oblong shape, and perforated with many foramina for the passage of the first pair or olfactory nerves. Along the central part of this surface there is an eminence, the crista galli, to which the falx major is attached. On either side of this crest is a deep furrow for lodging the bulbs of the olfactory nerves; and at the anterior part of this furrow, close to the crest, is a narrow slit which gives passage to the nasal branch of the ophthalmic nerve. The crista galli, at its anterior portion, projects into two little pro- cesses or alee which connect it with the frontal bone. From the under surface of the cribriform plate, along the middle line, descends the nasal lamella or vertical septum. This is a broad plate of bone, thick before where it joins the nasal bones and the nasal process of the frontal bone, thick behind and above where it unites with the sphenoid, and thin below where it joins the vomer and nasal cartilage. Upon the sides of this nasal septum are seen canals ending in grooves, some oblique and others vertical, for transmit- ting the olfactory nerves. Upon each side of this septum is the roof of the nostril; and upon either side are also ob- served two irregular bones, the superior and middle turbi- nated or spongy. Next to these is a range of cells; and upon the outside of this again an external surface, smooth and plane, the os-planum, and forming the internal plate of the orbit of the eye. The superior and middle turbinated bones are very thin and spongy scrolls or curved laminge of bone, the one above the other — the upper con- taining the superior meatus, the lower having the middle meatus, and being the more curved and the larger of the two. The ethmoid cells lie between the turbinated bones and the os-planum and uriguis, or between the nasal and orbi- tal surfaces, being bounded above by the cribriform plate. They are twelve or fourteen in number, and are divided, by a bony partition, into an anterior and posterior set. The posterior communicate with the superior meatus, and are small, and one of the upper sometimes opens into the sphe- BOXES OF THE CRANIUM. 191 FIG. 43— A FIG. 43— B j noid cells. The anterior are more numerous and larger; they open into the middle meatus, and one of the most an- terior cells forms a kind of infun- dibulum which opens above into the frontal si- nus, and ends below in front of the maxilla- ry sinus or an- trum Highmori- anum. The pitu- itary membrane extends from the nose, and lines the whole of the cells. Its struc- ture is mostly compact, consisting of very thin brittle plates of bone; the spongy tissue is found in the crista-galli and turbinated FIG. 43, A represents cerebral surface of the Sphenoid Bone. 1 1 Lesser wings or alae minores. 2 2 Upper extremity of greater wings. 3 ^Ethmoid spine. 4 Optic foramen. 5 Anterior clinoid process. 6 Posterior clinoid. 7 Sphenoidal fissure or foramen lacerum anterius. 8 Foramen rotundum. 9 Foramen ovale. 10 Foramen spinale. 11 Styloid process. 12 External pterygoid process. 13 Internal pterygoid process. 14 Pterygoid foramen. 15 Articular surface for cuneiform process of occiput. 16 Sella turcica. FIG. 43, B represents the anterior and inferior surface of the Sphenoid, a a Lesser wings of ingrassias. 6 6 Greater wings, c jEthmoidal spine, d Azygos process, e e Sphenoidal cells. // Posterior clinoid processes, g g Sphenoidal fissure, h h Foramen rotundum. i i Cavities for the middle lobes of the cerebrum, j j Surface for the temporal muscle, k k Styloid process. I I External pterygoid process, m m Internal pterygoid process, n Pterygoid foramen, o o Articular surface for the frontal bone, p Sella turcica. 192 BONES OF THE CRANIUM. portions. Its development takes place from three centres of ossification, one for the middle septum, and one for each, lateral half. Ossification commences first in the lateral portions, about the fifth month, (seen in the os-planum first.) The middle part is not ossified till after birth, and the cells are not complete till about the fifth or sixth year. Before this period they are Ml, solid, and entirely cartila- ginous. It is articulated with two bones of the cranium — the frontal and sphenoid, and 11 of the face, viz: the 2 superior maxillary, 2 lachrymal, 2 nasal, 2 palate, 2 inferior turbinated, and the vomer. Sphenoid Bone — (o$qv, a wedge.) The Sphenoid bone re- ceives its name from the manner in which it is wedged in or surrounded by all the bones of the cranium. Its situa- tion is at the base of the cranium, stretching transversely from side to side. Its form has been compared to the bat, to which there is some resemblance, when the ethmoid is attached. It is divided into a body and processes. The processes constitute the wings and feet of the bat. The body occupies the centre of the bone, and presents upon its anterior surface the azygos process, which articu- lates with the superior end of the vomer. A small groove for vessels is seen on each side of this process. The poste- rior surface is flat and rough, for articulation with the cuneiform process of the occipital bone. On the superior surface there is a deep cavity called the sella turcica. This is perforated by foramina for the passage of vessels, and lodges the pituitary gland. It is bounded by a thin plate of bone which rises almost perpendicularly at its posterior part, and terminates in two processes called the posterior dinoid, to which the tentorium is attached. At the anterior part of the sella turcica is an eminence called the olivary, where is also seen a groove marking the course of the optic nerves. The sides of the sella turcica, are grooved for the internal carotid artery. From the superior and outer extremities of the body, proceed transversely outwards, two long and thin pro- cesses called the alce-minores 3 the lesser wings or apopJiyses BONES OF THE CRANIUM. 193 of Ingrassias. These end in a point and mark the position of the fissure of Sylvius, or the division between the ante- rior and middle lobes of the cerebrum. These lesser wings have processes projecting backwards towards the posterior clinoid, and sometimes uniting with them, called the an- terior clinoid processes. These are thick tubercles, and have in their base a large foramen for transmitting the optic nerve and ophthalmic artery. From the posterior and inferior part of the sides of the body, proceed outwards, upwards, and forwards, the alee- majores or greater wings. These processes present three surfaces, an Anterior or orbital, an external or temporal, and an internal or cerebral. The orbital surface or process , assists in forming the outer wall of the orbit, is smooth and some- what square. The temporal surface or process is divided by a transverse ridge, called the crest, into two portions, that above the crest helping to form the temporal fossa, that below entering into the formation of the zygomatic fossa. The^ inner or cerebral surface is concave, and with the temporal bone, receives the middle lobe of the cerebrum. From the junction of the greater wings with the body, descend the pterygoid processes. Each process is divided into an external and an internal plate. The external plate has the pterygoideus externus muscle attached to its outer side, and the pterygoideus internus to its inner side. The internal plate ends in a curved hook-like process, called the hamular process, is covered by a bursa, and over it the tendon of the circumflexus palati muscle plays. Between the two plates is the pterygoid-fossa, occupied by the Eustachian tube, and the tensor palati muscle. The space between the two pterygoid plates at their lower extremity, is filled by the pterygoid process of the palatine bone. Through the base of the pterygoid process runs the Vidian canal, which gives passage to the pterygoid branch of the fifth pair of nerves. The angle between the squamous and petrous portions of the temporal bone is occupied by a process called the spi- nous, which projects from the posterior part of each wing, 13 194 BONES OE THE CRANIUM. curving downwards and outwards. To it are attached the internal lateral ligament of the lower jaw, the laxator tympani, and the tensor or circumflexus palati muscles. This hone has a number of foramina. Beginning in front and proceeding backwards, we observe, first, at the root of the lesser wings, the foramen opticUm for the optic or nerves of sight; second, the foramen rotundiim, in the base of the greater wing, where it joins the body. This opens into the pterygo-maxillary fossa, and transmits the superior max- illary nerve. Behind it, about half an inch, is the foramen ovale, which gives passage to the inferior maxillary nerve; and a little posterior to this again is a small opening, the foramen spinale, through which passes the middle menin- geal artery. Between the lesser and greater wings is a long slit, the foramen lacerum superius or orbitale, wide inter- nally, narrow externally, and transmitting the third, the fourth, the first branch of the fifth, and the sixth pair of nerves, together with several filaments of the sympathetic nerve and the ophthalmic vein. Between the posterior part of the greater wing and the petrous portion of the temporal bone there is another slit, the foramen lacerum medius; and at the base of the pterygoid process, as stated, the Vidian foramen. The structure of the sphenoid is cellular in the body and bases of the processes, compact every where else. At about the age of ten years the body is hollowed into cavities called the sphenoidal sinuses. In front of them are two triangular pyramidal bones, called, after their discoverer, the ossapyr- amidalia Wisterii, or the sphenoidal turbinated bones. The base of each of these is anterior, and connects with the eth- nioidal bone and its cells; the apex is posterior, and unites with the sphenoidal sinuses. These pyramids of Wistar are found to be fused into the body of the sphenoid from about the fifteenth to the eighteenth year. The development of this bone has been noticed to begin from as many as twelve points of ossification, viz : 4 for the body, 4 for the wings, 2 for the pterygoid processes, and 2 for the pyramids of Wistar. At birth the sphenoid is seen GENERAL REMARKS ON THE CRANIUM. 195 to consist of three pieces,, viz : 1 and 2, the greater wings and pterygoid processes of either side, and 3, the lesser wings and body in a single piece. The sphenoidal spongy bones, or pyramids of Wistar, belong also to the latter piece. Ossi- fication is noticed in the various parts in the following order, viz: 1. In the greater wing and external pterygoid process, about the seventh or eighth week. 2. Lesser wings and posterior body, at the close of the second month. 3. Anterior body, at the end of the third month. 4. The in- ternal pterygoid plate has a separate ossific point, which is stated to unite with the external pterygoid about the middle of the fourth month. The centres for the posterior portion of the body, and those for the anterior and lesser wings, are seen to unite first; then the greater wings and pterygoid processes. The latter unite with the body during the first year; the pyramids of Wistar join it about puberty, at which time this bone becomes connected with the ethmoid ; while the body of the sphenoid joins the occipital bone between the eighteenth and twenty-fifth years. The sphenoid is articulated with all the bones of the cra- nium and five of the face, viz: the two malar, two palati, and the vomer. GENERAL REMARKS ON THE CRANIUM. Under the head of the osseous tissue the different articu- lations were described. Synarthrosis was stated to denote the articulation of bones that have no motion, and suture the mode of union between the different bones of the cra- nium. The c&ronal, the sagittal, the lambdoid, the squamous, the sphenoid, and ethmoid, constitute the principal sutures. (See Fig. 53.) The coronal suture connects the anterior edges of the pa- rietal bones with the superior margin of the frontal, and extends from side to side over the superior and anterior surface of the cranium. The sagittal unites the parietal bones along the median line, and extends, from the superior angle of the occipital 196 BONES OF THE FACE. bone forwards, to the centre of the coronal suture. The two extremities of this suture occupy the place of the anterior and posterior fontanelles. The lambdoidal connects the posterior edges of the parietal with the superior margin of the occipital hone, and extends from the posterior end of the sagittal suture, on either side, to the mastoid process of the temporal bone. An extension of this suture, under the name of the additamentum sutures, lambdoidalis, reaches as far down as the foramen lacerum posterius, passing between the mastoid and petrous portions of the temporal and the occipital bones. In this suture we find the ossa triquetra or wormiana. The sphenoid suture is as extensive as the very irregular edge of the sphenoid bone, connecting with it the ethmoid, frontal, parietal, temporal, and occipital bones of the cra- nium. The ethmoid suture in the same way surrounds the ethmoid bone, uniting it with the frontal and other bones. The diameters of the cranium are thus given by Bichat: The antero-posterior is about five inches, and extends from the foramen coecum in front, to the internal occipital pro- tuberance behind. The transverse diameter is four inches and a half, and extends between the bases of the petrous portions of the temporal bones. The vertical diameter is somewhat less than the transverse, and reaches from the middle of the sagittal suture to the anterior edge of the foramen magnum. SECTION II. BONES OF THE FACE. The Superior Maxillary Bones — (ossa maxillaria superi- ora.) The superior maxillary is the principal and largest bone of the face. It enters into the formation of the orbit, the nose, the mouth, and the palate. It is situated so as to form the greater part of the front of the face. Its shape is somewhat triangular, though very irregular. *The two taken together are symmetrical, each lateral portion com- BONES OP THE FACE. 197 ing in contact upon the median line. It is divided into body and processes. The body presents five surfaces for examination. 1, the anterior or facial ; 2, the internal or A FIG. 44. nasal; 3, the superior or orbital; 4; the inferior or palatine ; 5, the posterior or zygomatic. The anterior surface is concave, and called the canirie fossa. At the upper part of this fossa is the infra-orbital foramen, for transmitting the infraorbital vessels and nerve. From the upper and inner part of this fossa the nasal process of the superior maxilla arises. It ascends and forms the side of the nose. Its superior edge is ser- rated and articulates with the frontal bone. Its anterior edge is smooth and unites with the nasal bone and the FIG. 44, A represents an outer view of the superior maxilla of the left side, a Orbitar process. 6 Infra-orbitar canal, c Situation of the os-unguis. d Superior portion of lachrymal canal, e Articulating surface for frontal bone. / Articulating portion with nasal bone, g Anterior part of the floor of the nostril, 'h Point of articulation with its fellow, i Alveolar process, j Canine fossa, fc Articulating surface for the malar bone. FIG. 44, B represents an inner view of the superior maxilla of the left side. a Maxillary sinus or Antrum of Highmore. 6 Ductus ad nasum. c Articular point for the frontal bone, d Articular edge for the nasal bone, e Surface for the nasal cartilage. / Anterior point of the floor of the nostril, g Artic- ulating surface for the bone of the right side, h Foramen incisivum. i Pala- tine process, j Articulating edge for the palate bone, fe Anterior articulating ridge for inferior turbinated bone. I Articular surface for the palate bone behind, m Surface for the nasal portion of the palate bone, n Surface for the orbitar plate of the palate bone, o Termination of nasal duct. 198 BONES OP THE FACE. alar cartilage. The posterior is round, and forms the inner border of the orbit, and immediately posterior to this bor- der is a deep groove, the lachrymal fossa, for the nasal duct. Its anterior surface has the orbicularis palpebarum and levator labii superioris alceque nasi muscles attached to it. Its internal surface forms part of the nares. The canine fossa is bounded externally by a rough, serrated surface, the malar process, which is concave and smooth behind for receiving the temporal muscle. From between the nasal and malar processes, and pro- jecting backwards, so as to form the floor of the orbit, is the superior or orbital surface or process. This surface has a triangular form; its base is internal and connected with the unguiform, ethmoid, and palate bones. Its posterior border helps to form the splieno-maxillary fissure. Its ex- ternal unites with the malar bone, and its middle surface is channeled into a canal, the infra-orbital canal, which terminates in the infra-orbital foramen. This process is a very thin plate of bone forming the roof of the antrum as well as the floor of the orbit. The infra orbital canal, at its anterior part, divides into a smaller canal, the anterior dental, which descends in the anterior wall of the antrum to the anterior alveoli. The posterior surface of the superior maxillary bone is posterior and below the orbital. Its most prominent feature is the tuberosity, which is larger in the young subject, as it then contains the last molar tooth, and has three or four small foramina, called the posterior dental canals, which lead to the posterior alveoli, and transmit to the molar teeth the posterior dental nerves and arteries. The infe- rior portion of the tuberosity presents a rough surface for articulation with the palate bone, and above and to the inner side of this point of articulation, is a smooth canal, which forms a portion of the posterior palatine canal. The inferior or palatine surface of the upper jaw consti- tutes the floor of the nostrils and the roof of the mouth, which corresponds in situation to the inter-maxillary bones of inferior animals. BONES, OF THE FACE. 199 To the practical dentist, Mr. Nasmyth uses the follow- ing strong language in reference to these bones : "These bones serve most importantly to render the upper jaw pliant during the actions of the mouth in the early years of life, and they are also of high account in promoting by their growth the latitude necessary for the proper arrange- ment of the teeth. As a means also of preventing concus- sion of the teeth, they are valuable accessories in the mechanism of the mouth." He thus describes their anat- omy: aln the foetal skull, at the point of junction of the posterior with the middle third of the foramen incisivum, a fissure may be observed, which passes upwards into the anterior palatine canal on each side, and may be traced onwards to the floor of the nasal cavity. Having reached the latter situation, it inclines obliquely backwards and outwards for the distance of about a line, and then bends forwards and upwards for a space of two or three lines to the base of the nasal process of the superior maxillary bone, terminating upon the latter at one or two lines below the ridge for the inferior turbinated bone. If the foramen incisivum be again examined, another fissure will be ob- served on the oral surface of the palate, passing directly outwards to the alveolus of the canine tooth, and curving gently backwards in its course. The portion of bone which lies anterior to these fissures on each side, and which sup- ports the incisor teeth, is the inter-maxillary bone."* This surface is also called the palatine process of the superior maxillary bone. It is smooth and concave above, where it forms the nares, and rough below where it forms the mouth. Its anterior boundary is very thick, and con- stitutes the alveolar arch and processes. This arch has eight conical cavities for the teeth, and when united with its fellow, completes the circle and con- tains sixteen in all. The cavities are separated by parti- tions of dense cellular tissue, and have their shape corre- sponding to the variety of teeth they accommodate. The walls of these cavities form the alveolar processes. The * Nasmyth's late Researches. 200 BONES OF THE FACE. alveolus of the central incisor has, according to Mr. Nasmyth, the septum between it and its fellow twice as thick as that of the other teeth; its antero-posterior diameter one-third greater than at the sides, and its lateral diameter one third greater in front than behind. Its anterior wall is so thin as to be sometimes incomplete. The alveolus of the lateral incisor has less depth than the central, its septum between the latter is not so thick as between it and the canine, its posterior wall is thicker than the anterior, and its antero-posterior diameter is greater than the lateral. The alveolus of the canine ascends above the level of the roof of the mouth, and is the deepest of all the alveoli ; it corresponds to the anterior wall of the maxillary sinus, is of oval form as the incisors, and has its antero-posterior diameter about one tenth greater than the latter, and look- ing backwards. The alveolus of the first bicuspid has its inferior part partitioned into two cavities for the roots, the external being the larger, while its middle is found narrowed. Its depth is equal to the second bicuspid, but not so great as the canine, and the septum between it and the latter is not so great as that separating it from the second bicuspis. The alveolus of the second bicuspis is not narrowed in its middle as the latter, nor divided by a middle septum into cavities, and its form is oval. The alveolus of the first molar is divided into three cavi- ties, two of which are external, the other internal ; the in- ternal is the largest, and the posterior external the smallest, hence a rule of practice for entering the antrum, founded upon the size and direction of these cavities, always is to select the internal or anterior external cavity for this pur- pose; the internal cavity occasionally looks to a division of itself, and is sometimes found to communicate with the pos- terior, in which case only one root, strong and broad, is seen instead of two. This alveolus is not unfrequently found to open into the antrum, on which account it is regarded as the most suitable one for perforating the antrum of High- BONES OF THE FACE. 201 more, as well as presenting the most dependent position of this sinus, though the antrum may be entered from the alveolus of either the second or first bicuspis, but the direc- tion would have to be obliquely backwards. The alveoli of all the molar teeth present the triple divis- ion for its roots, which latter sometimes very much diverge, and then again, on the contrary, greatly converge, so much as sometimes to present the appearance of a single root. Either too great divergence or convergence of the roots offers difficulties to extraction, and especially so when a portion of the alveolus is embraced. The posterior edge of the palatine process is thin and serrated to join the palate bone — internally it is thick where it unites with its fellow — and at the anterior part of this union is the anterior palatine canal, which opens superiorly into the nostrils by two foramina, and inferiorly on the mouth by one, the foramen incisivum. At the place of junction of the palatine processes, the upper edge in the nares is raised, and called the nasal crest, which receives the inferior border of the vomer. This crest projects forwards and forms the nasal spine, between which and the nasal process, the bone is rounded and concave, forming the anterior nares. The internal or nasal surface. — The nasal surface presents a very large opening situated between the middle and lower turbinated bones, and leading into a cavity called the antrum Higlimorianum, or maxillary sinus. This sinus is of a triangular or pyramidal shape, the base looking to the nose, the apex to the malar process. It is bounded above by the orbitar process of the superior maxillary bone, form- ing its roof, below by that portion of the alveolar arch cor- responding to the first and second molar teeth, constituting the floor ; in front by the canine fossa, and behind by the tuberosity. Its shape and size vary much in different bones. It is lined by the pituitary membrane of the nose. Its opening in the natural skeleton is much contracted by the ethmoid and lachrymal bones above and in front, by the inferior spongy below, and the palate bone behind. This 202 BONES OF THE FACE. opening, says Mr. Nasmyth, "presents much variety, both. in direction and position, sometimes looking obliquely for- wards, at others obliquely backwards, and being sometimes in the anterior and sometimes in the posterior portion of the nasal process." It is stated to be about the diameter of a crow quill, and when deprived of the soft parts, to measure from thirty to forty lines in circumference. The mucous membrane also diminishes the opening. The antrum has its cavity sometimes divided by septa into cells. Its roof has the infra-orbital canal running along it, and terminating in the infra-orbital foramen. This roof is very thin, and readily allows tumors of the antrum to project into the orbit. The floor has but a thin partition between the roots of the teeth and this cavity, so thin indeed in some cases, that the apices of the molar teeth are seen to project into the sinus, and hence this is here regarded as the most eli- gible spot for puncturing the antrum, and drawing off any purulent collections it may contain. By some, the alveolus of the canine tooth is thought most convenient for entering the maxillary sinus. The anterior and posterior walls of this sinus contain the anterior and posterior dental canals, for transmitting the dental nerves and vessels. The opening of the antrum communicates, by one or two small oblique orifices, with the middle meatus of the nose, and anterior to it is the funnel-shape tube, the infundibulum, connecting with the frontal sinus and anterior ethmoid cells. The foramina in each superior maxillary bone are six in number — 2 proper and 4 common. The proper are the infra-orbital and foramen incisivum. The common are the foramen of the antrum, the posterior palatine, the anterior nares, the opening into the nasal or lachrymal duct, and the splieno-maxillary fissure. The number of processes is eight, viz: the orbital, nasal, the tuberosity, the alveolar, malar, palatine, the nasal spine, and the nasal crest. The structure of the upper maxillary is thick and cellu- lar in its processes, and very thin, but compact about the BONES OP THE FACE. 203 antrum, and, though the largest of all the bones of the face, is nevertheless exceedingly light, on account of the great size of the antrum. Its development is not agreed on among anatomists. Six centres of ossification are enumerated, viz: one for the body and one for each of the processes, nasal, malar and palate, and two for the alveoli. Ossification, however, begins very early, about the end of the first or beginning of the second month of fcetal life, in the alveolar arch. The anterior palatine portion remains distinct for two or three years, and is called the os-incisivum or inter-maxillary, and represents the permanent condition in some of the in- ferior animals. At birth this bone has great transverse breadth, but little height, owing to the floor of the orbit and the alveolar arch coming so close together, which is, however, gradually remedied by the enlargement of the antrum or maxillary sinus. Its articulations are with two of the cranium, the frontal and ethmoid, and seven of the face, viz: the palate, the malar, nasal, lachrymal, inferior turbinated, vomer and its fellow. Palate Bones — (ossa palati.) The situation of the palate bones is at the posterior part of the nares. They contribute to form the floor of the or- bit, the side of the nose, and the palate. They are symmetrical. The/bra is irregular, though it has FIG. 45, A represents a posterior view of the Palate Bone, a Nasal surface horizontal plate. 6 Nasal surface of ascending plate, d Articulating border for its fellow, c, fc, I Pterygoid process. / Process formed by junc- tion with its fellow, g Horizontal articulating ridge for inferior turbinated bone, h Spheno palatine foramen, t Orbital process, j Sphenoidal process. FIG. 45, B represents ascending plate of Palate Bone, on its spheno-maxil- lary surface, a Articulating surface with superior maxillary bone. 6 Poste- rior palatine canal, c Spheno-palatine foramen, d Spheno-maxillary face. t Orbital face. /Maxillary face, g Sphenoidal process, h Pterygoid process. 204 BONES OF THE FACE. some resemblance to the letter L. The palate bone is divided into two portions, the horizontal or palatine and the vertical or nasal portion. The horizontal portion is quadri- lateral, and forms the posterior part of the hard palate. Its upper surface is concave from side to side, and forms the posterior nares, and where it unites with its fellow there is a crest to connect with the vomer. This crest continues backwards into a projecting process, constituting the poste- rior nasal spine, to which the azygos uvulae muscle is at- tached. The lower surface of the horizontal plate is rough and completes the arch of the palate. Its anterior edge is serrated obliquely and rests upon the palatine process of the superior maxillary. Its posterior edge is thin and con- cave and gives attachment to the velum palati. The vertical or nasal plate rises perpendicularly from the horizontal, and is thin and broad; it presents two surfaces, an external and internal, and two edges, an anterior and posterior. The external surface is uneven and rough in front where it unites with the superior maxillary. It is grooved into a canal — the posterior palatine canal — for the passage of the palatine vessels and nerves. This canal is bounded in front by the tuberosity. The inner or nasal surface is divided by a transverse ridge to which the infe- rior turbinated bone is articulated. This ridge has a de- pression above and below it; the upper corresponds to the middle meatus, the lower to the inferior meatus of the nose. At the point of junction of the nasal with the horizontal plate is the pterygoid process or tuberosity. It is thick, and wedge-shaped, and occupies the space at the lower part, and between the two plates of the pterygoid processes of the sphenoid bone. It presents three surfaces, two lateral uniting with the pterygoid plates, and one posterior and concave forming part of the pterygoid fossa. One or two small foramina perforate this process from the palatine canal. At the superior extremity of the nasal plate are seen two processes,, the orbital and sphenoidal. The orbital is anterior and the larger of the two ; it is triangular and is situated in the most posterior part of the floor of the orbit, BONES OF THE FACE. 205 and is united by its internal edge to the ethmoid, by its anterior edge to the superior maxillary, and by its posterior to the sphenoid bone. The sphenoidal process is smaller, and posterior to the orbital. Its external lateral surface assists in forming the spheno-maxillary fossa; its internal helps to form the nares, and its superior articulates with the sphenoid bone. Both of these processes are cellular and communicate with the cells of the sphenoid and eth- moid. They are separated by a large opening, the spheno- palatine foramen, which gives passage to the spheno-palatine nerve and artery. The palate bone has four foramina, one proper and three common. The posterior palatine is the proper, and the spheno-palatine, the pterygo-maxillary canal, and the spheno-maxillary fissure are the common. Its processes are seven in number, the nasal, palate, pterygoid, orbital, sphenoidal, posterior nasal spine and crest. Its structure is mostly compact and thin, except in the processes. Its development is by a single centre of ossi- fication, about the middle of the second month, at the point of union of the horizontal and vertical plates. It is articu- lated with the sphenoid and ethmoid of the cranium, and with four of the face, the superior maxillary, vomer, infe- rior turbinated, and its fellow. Malar Bones — (ossa-malarum.) The malar or cheek bones are in pairs, and occupy a prominent situation on each side of the face, at the outer and under portion FIG. 46. of the orbit. Their form is quadrilateral. The external surface of each is convex, and has one or more small foramina for the passage* of vessels and nerves, and also has the orbicu- laris palpebrarum covering it. From the upper part of this bone ascends the superior or external orbital process to join the frontal bone. From its inner portion FIG. 46 represents an internal view of the right Malar Bone, a Superior or external orbital process to join the frontal bone. 6 Orbitar process, c Malar foramina, d Maxillary process, t Lower edge of the malar bone. /Zygo- matic process, g Posterior concave surface, h External edge. 206 BONES OF THE FACE. is the maxillary process whicli articulates with, the maxil- lary bone. From between these two processes the bone is smooth and round, and forms about one third of the lower and outer margin of the orbit. From this margin there projects backwards into the cavity a thin plate of bone called the internal orbital process. This process joins the sphenoid and superior maxillary bones, and is notched posteriorly where it bounds in front the spheno-maxillary fissure. The lower margin of the cheek bone has the masseter muscle attached, and from its posterior end proceeds the zygomatic process, upon which rests a similar process from the tem- poral bone. The internal or posterior surface is concave and smooth, and forms part of the temporal fossa. The structure is thick and cellular, having a delicate compact covering. The development is from a single point of ossification, commencing about the latter part of the second month. It is articulated with four bones, i. e. frontal, sphenoid, tem- poral, and superior maxillary. Lachrymal or Unguiform Bones, (pssa-unguis) The lach- rymal or tear bones are two in number, and situated at A. FIG. 47. B. the anterior and inner portion of the orbit. Their form is oval, and present an outer or orbital surface, which is smooth and forms a portion of the in- ner orbit. At the anterior part of this surface is a vertical ridge, within which is a deep groove, to unite with a corresponding one in the posterior part of the nasal process of the superior maxillary, constituting the upper portion of the nasal duct and lodging the lachrymal sac. The internal or nasal surface is rough and covers the anterior ethmoid cells. FIG. 47, A represents right side of os-unguis or Lachrymal Bone, upon the or- bitar or outer aspect. 1 Upper margin. 2 Posterior margin. 3 Vertical ridge. 4 Inferior margin. 5 Anterior margin. FIG. 47, B represents the inner aspect of the same bone. 1245 Show the same points as in A. The vertical groove is seen in this figure. BONES OF THE FACE. 201 The structure of these bones is entirely compact, very thin, transparent, and among the most brittle of all the bones. The development of each bone is by a single point of ossification, which is said to be completed at the begin- ning of the third month. The articulations are with four bones, i. e. two of the cranium and two of the face. By its superior and posterior edges it is united to the frontal and ethmoid, and by its inferior and anterior edges to the superior maxillary and lower turbinated bone. Nasal Bones — (ossa-nasi.) The bones of the nose are situated between the nasal processes of the superior maxil- lary, and below the frontal. They are A- FlG- two in number, and meet along the median line, so as to form an arch called the bridge of the nose. This arch is thick and narrow above, where it joins the frontal bone, and thin and expanded below where it connects with the cartilage. The external surface is convex and covered by the pyramidalis and compressor nasi muscles. The internal surface is con- cave and receives the nasal branch of the ophthalmic nerve. The structure of the nasal bones consists of two compact tables, with intervening diploe. Their development takes place by a single point of ossification about the end of the second month. The articulation is with four boneg, i. e. the frontal and ethmoidal of the cranium, and the superior maxillary and its fellow of the face. Inferior Turbinated Bones — (ossa turbinata inferiora.) (Fig. 49.) The inferior turbinated or spongy bones are situated at the lower and outer part of the nares. Their FIG. 48, B represents an anterior view of the nasal bones. « Inferior ex- tremity. 5 Articulating surface for its fellow, c Articulating edge for the superior maxillary bone, d Groove on inner side for nasal nerve, e Articu- lating border for frontal bone. / Foramen for nutritious artery. FIG. 48, A represents a posterior view of nasal bones, a Inferior extremity ft Articulating margin for its fellow, c Articulating margin for superior maxilla, d Groove for internal nasal nerve, t Articular border for frontal bone. / Lower portion of groove for the nasal nerve. 208 BONES OF THE FACE. greater length extends from before backwards. They are two in number and have an irregular form. Each presents FIG. 49. two surfaces, an internal or convex, and external or concave. The superior edge is united to the maxillary and palate bones by their transverse ridges, and from it ascends a small pyramidal process connecting with the unguis to complete the nasal duct. The inferior edge is free and rolled outwards. The anterior point forms the inner wall of the lower orifice of the nasal duct. The structure is thin, brittle, and filled with small pores. The development is by a single point from the centre, commen- cing about the fifth month of foetal life. The articulations are with four bones, the superior maxillary, the lachrymal, the ethmoid and palate. Vomer — (the plough-share.) The vomer, a single bone, so called from its supposed resemblance to the plough-share, or, more properly, the coulter of the FIG. 50. plough, is situated on the median line so as to divide the nares. It has two ^ surfaces, which are lateral, and covered by the pituitary membrane, and four edges, a superior, an inferior, an anterior, and a posterior. The superior is thick and hollow, and receives the azygos process of the sphenoid bone. The inferior is long and united to the palatine crest of the superior maxillary and palate bones. The anterior edge is grooved to receive the middle septum of the ethmoid bone and nasal cartilage ; while the posterior is sharp and divides the nares behind. Its struc- ture is compact, thin, and transparent. Its development is from a single point, commencing about the end of the second month, at its lower portion. Its articulation is with FIG." 49 represents the maxillary or outer aspect of the right Turbinated Bone. 1 2 Posterior and anterior angles of the turbinated bone. 3 Lachry- mal process. 4 Maxillary process. 5 Lower margin. 7 Curved portion of the maxillary process. FIG. 50 represents the yomer in profile. 1 2 Superior edge, 3 Anterior edge, 4 Inferior edge of Tomer. 6 Lateral surface. BONES OP THE FACE. 209 six bones, i. e. the sphenoid, ethmoid, two upper maxillary, and two palate. Inferior Maxillary Bone — (os maxillare inferius^—The inferior maxilla, or lower jaw, is situated at the lower part of the face, occupying the front and sides, and extending as far back as the base of the1 skull. Its form is semi-circu- lar, and consists of a body and two extremities. The body forms the central and lateral portions. The central portion is prominent, known as the chin, and has a vertical ridge along its median line, the sympliysis menti, which denotes the original separation -of this bone into two symmetrical parts. The anterior surface of the chin often presents a trian- gular shape, the base below having, at either end, a promi- nent process, while the apex is above. On either side of the symphysis is a depression for the origin of the depres- sor labii inferioris muscle; and external to this is an ob- lique opening, the anterior mental foramen, through which come out the inferior dental nerve and artery. On the posterior part of the chin the surface is concave, except in the middle line of the symphysis, where is seen a chain of eminences. To the upper one of these is attached the fre- num linguce, to the middle, the genio-hyoglossi, and to the lower, the genio-Jiyoidei muscles. On either side of this middle line, and at the upper part, are two depressions for the sublingual glands, and, at the lower part likewise, de- pressions for the digastric muscles. The lateral portions take a direction outwards and backwards; on their exter- FIG. 51 represents the inferior Maxillary Bone, a Body ; 6 Ramus ; c Sym- physis menti ; d Alveolar process ; e Anterior mental foramen ; / Base ; g Groove for the facial artery ; h Angle ; i Posterior portion of ridge for the mylo-hyoid muscle ; j Coronoid process ; k Condyle ; / Neck of Condyloid pro- cess; m Posterior mental foramen ; n. Groove for inferior maxillary nerve ; o Molar teeth ; p Bicuspid teeth; q r Middle and lateral incisors. 14 210 BONES OF THE FACE. nal surface is an oblique ridge running backwards and upwards to the root of the coronoid process, to which is attached the depressor-anguli oris and platzsma in front, and the masseter muscle behind. On the internal surface is also an oblique ridge, called the mylo-hyoid ridge, which gives attachment to the mylo- hyoid muscle in front, and the superior constrictor of the pharynx and intermaxillary ligament behind. Beneath this ridge is a groove for the mylo-hyoid nerve, and below this an oblong depression for the sub-maxillary gland. The lower border of the jaw, called the base, is thick and rounded. The upper border is the alveolar arch, having its alveolar processes and cavities corresponding to the va- riety of teeth they receive. The alveolar cavity of the mid- dle incisor has its antero-posterior diameter the broadest, and the septum between it and its fellow thicker than that separating it from the lateral. The alveolus of the lateral incisor has its opening wider in front than behind, and is described as being indented on its outer side. Its anterior wall is a little convex, the posterior concave, and its late- ral septa thicker behind than in front. The alveolus of the canine is found to be larger than that of either the incisors or bicuspids. Its form is conical, with the sides compressed and presenting, laterally, a depression cor- responding to the root of the tooth. Its anterior wall is said to be more prominent and thinner than any other in the dental arch, and looks backwards and downwards, while the posterior is directly vertical. The axis of the canine is forwards and upwards, and the opening of its alveolus is said to be twice the breadth in front that it is behind. Its form is oval. The alveolus of the first bicuspid has its form conical, its sides compressed, its outer surface flat, and its inner rather concave. It is smaller than the canine, has its opening oval, with edges in front and behind seen to be a little indented. Its antero-posterior diameter looks outwards and forwards, its vertical obliquely inwards. The alveolus of the second bicuspidh&s its vertical axis look- BONES OF THE FACE. 211 ing, says Mr. Nasmyth, downwards and backwards ; a fact which he regards of great practical moment in the man- agement of the teeth, as a space is thus gained of three or four lines hetween the roots of the two bicuspids. This alveolus is larger than that of the anterior, hut less than that of the canine. The alveolus of the first molar has a partition dividing it into an anterior and posterior cavity — the anterior being rather the larger, and the axes of both looking backwards. The septum is described as thickest in the centre, abound- ing with openings for the passage of vessels, and has its direction inwards and backwards from the outer side. Its opening is of a quadrilateral form, having its front margin indented. The alveolus of the second molar has also a septum (occasionally absent) dividing it into an anterior and pos- terior cavity, the anterior being the larger, and found to be somewhat contracted in its middle and "compressed from before backwards;" the posterior is oval and not so deep. Its opening is also quadrilateral. The alveolus of the third molar is always smaller and shal- lower than either of the others, and is found to present great variety both in form and size. It is seen sometimes divided into two cavities, and then again having but one. The alveoli of the molar teeth all look outwards, so that the crowns of these teeth have a direction inwards.* At the posterior extremity of the lateral portions is the angle, which is nearly a right angle in the adult, but quite obtuse in the foetus, and to which, on its internal edge, is attached the stylo maxillary ligament. From the posterior ends of the lower jaw there rises, almost perpendicularly, a process called the ramus. This process is square-shaped and very strong. It has different angles at different periods of life. In the infant it is nearly on a line with the lateral portions. In youth it is oblique. In the adult it becomes nearly ver- tical, while in old age it again returns to the infant state Its external surface is covered by the masseter muscle * Alexander Nasmyth's late Researches on the Teeth. 212 BOKES OF THE FACE. Its internal surface has, in the centre, the posterior mental or inferior dental foramen, which transmits the inferior dental artery and nerve. This foramen is protected by a shelf of bone to which is attached the internal lateral liga- ment, and it leads to a canal which passes beneath the alveolar cavities, with each of which it communicates, and conducts to the teeth their nerves and vessels. Below this posterior foramen is the insertion of the pterygoideus inter- nus muscle. The ramus terminates above in two processes, viz : the anterior or coronoid, and posterior or condyloid. The coronoid process is triangular and is surrounded by the tendinous insertion of the temporal muscle. The ante- rior border of the root is grooved for the buccinator muscle. The condyloid process is oblong and has its greatest diam- eter looking obliquely backwards and inwards. Its upper surface is smooth and covered with a movable fibro-carti- lage, intervening between it and the glenoid cavity of the temporal bone with which it articulates. Around the base of the condyle there is a contraction called its neck, to the anterior and inner portion of which the pterygoideus exter- nus muscle is inserted. The curve between the two pro- cesses is the sigmoid notch, over which pass the masseteric artery and nerve. The structure of the lower jaw is compact externally, and spongy or cellular within. The walls of the alveoli and their partitions are also spongy. The interior of this bone has already been stated to be traversed by the inferior maxillary or dental canal. This canal, commencing at the posterior dental foramen, gradually contracts as it proceeds forwards under the summits of the alveoli. At the second bicuspid tooth it divides into two canals, the one large, terminating at the anterior mental foramen, the other small and continued forward in the line of the original canal, to the incisor teeth, to which it is dis- tributed. The situation of this canal varies at different periods of life. In the infant, at birth, according to Cruveilhier, it occupies the lowest portion of the jaw. After second den- ARTICULATION OF THE LOWER JAW. 213 tition, it is nearly on a line with the mylo-hyoid ridge-; and in old age, when the teeth are lost, it runs along the alveolar "border. Its size also varies. Before the appear- ance of the second teeth, and in the foetus, it is observed to be very large ; it diminishes in the adult, and contracts still more in old age. The development of the inferior maxilla is by two points of ossification, one for each lateral half; their common point of union being the symphysis. It and the clavicle are the first bones formed. The lower edge of this bone is seen to commence ossifying about the end of the first month, and about the end of the second, each half of the bone pre- sents a groove common to the dental canal and alveoli. Union of the symphysis occurs during the first year. ARTICULATION OF THE LOWER JAW. It articulates with the temporal bones at the glenoid fos- sae, and with the sixteen lower teeth. The condyles of the inferior maxilla and that portion of the glenoid cavity of the A FIG. 52. B temporal bone, in front of the glasserian fissure, constitute the bony portions which enter into the movable articulation FIG. 52, A represents an external view of the Articulation of the Lower Jaw. a Zygomatic arch. 6 Tubercle of the zygoma, c Ramus of the lower jaw. d Mastoid process of the temporal bone, e External lateral ligament. / Stylo- maxillary ligament. FIG. 52, B represents an inner view of the same articulation, a Section through the petrous portion of the temporal bone and spinous process of the sphenoid, b Internal view of part of the body and ramus of the lower jaw. c Interfial portion of the capsular ligament, d Internal lateral ligament. e Point for passage of the mylo-hyoid nerve. / Stylo-maxillary ligament. 214 ARTICULATION OP THE LOWER JAW. of the lower jaw, and which, are covered with cartilage. The other elements of this joint consist of, 1. A capsular ligament, 2. External and internal lateral ligaments, 3. Interarticular cartilage, 4. Two synovial membranes, 5. Stylo-maxillary ligament, 6. Intermaxillary ligament. The capsular ligament extends from the glenoid fissure and zygomatic eminence to the neck of the lower jaw. It consists of strong fibres, though it is deficient internally and in front where the external pterygoid muscle is at- tached. This ligament is connected internally with the interarticular cartilage and synovial membranes, and ex- ternally with the external and internal lateral ligaments. The external lateral ligament extends from the zygomatic process of the temporal bone at its root, to the neck of the condyle of the lower jaw, at its outer side. It is short and narrow, and is regarded simply as a thickening of the cap- sular ligament upon its external side. This ligament is hid by the parotid gland. The internal lateral ligament extends from the spinous process of the sphenoid bone to the spine, which overhangs the posterior mental foramen ; it is longer and thinner than the external, and serves to protect the inferior dental artery and nerve, which are situated between this ligament and the bone. The interarticular cartilage is situated within the joint and divides it into two distinct cavities, which sometimes, however, communicate by an opening in the centre. This cartilage is 'oval transversely, and consists of concentric fibres, very compact, and more distinct and thick at the cir- cumference than at the centre. It is attached to the cap- sular ligament, and by presenting a movable socket, is believed to strengthen as well as to guard against dislo- cations. Of the two synovial membranes, the larger is superior and GENERAL REMARKS ON THE SKULL. 215 covers the glenoid cavity, the cartilaginous portion of the zygomatic eminence, the upper surface of the inter articular cartilage, and the capsular ligament. The smaller synovial membrane covers the cartilaginous surface of the condyle, the lower surface of the interarticular cartilage, and is also reflected upon the inner wall of the capsular liga- ment. These synovial capsules are generally complete sacs, having no communication, and their function is to secrete a fluid to lubricate and thus facilitate the move- ments of this joint. The stylo-maxillary ligament extends from the styloid process of the temporal bone to the angle of the lower jaw. It consists of a delicate aponeurosis, and has but little to do with the articulation. The intermaxillary ligament also has little to do with the joint, and is hardly considered deserving the name of a ligament It is seen extending from the external ptery- goid plate and contiguous portion of the superior maxilla above, as an aponeurotic band, to the root of the coronoid process of the inferior maxilla below, and forming a com- mon point of attachment for the buccinator and superior constrictor muscles of the pharynx. The motions of this joint consist of elevation, depression, the forward, back- ward, and lateral movement performed by the muscles of mastication. GENERAL REMARKS ON THE SKULL. Anatomists distinguish in the skull five regions, an an- terior, a superior, an inferior and two lateral regions, (Fig. 53.) The anterior region is the face, and presents somewhat fheform of an oval. Its surface is very irregular, having cavities for the accommodation of two of the senses, seeing and smelling. Its outline may be traced by draw- ing a semi-circular line above, through the protuberances of the frontal bone, and extending it laterally round the ex- ternal angular processes of the same bone, and thence con- tinuing it along the outer margin of the malar to the lower jaw, running along its lower border. So that the facial 216 GENERAL REMARKS ON THE SKULL. FIG. 53. surface includes the bones of the face with a portion of the frontal bone. In the superior part of this surface, on the median Iine7 is seen the nasal tuberasity, on either side of which are the superciliary ridges. Below these are the superior orbit- ary margins, with the supra orbital holes at their inner third; for the transmission of the supra-orbital nerve and artery. Below the nasal tu- berosity is the nasal spine of the os frontis, next are the nasal bones forming the bridge of the nose ; on either side of which are seen the nasal processes of the superior max- ** illary bones, the internal an- gular processes of the os fron- tis, and still more externally the openings of the orbits. Below the ossa nasi are the anterior nares, on the inferior and central margin of which is the anterior nasal spine, and below this again are the symphysis of the upper jaw and the alveolar arch and processes. On either side of the anterior nares are the canine fossae for giving origin to the levator anguli oris muscle ; above this is the infra-orbital foramen, transmitting the infra- FIG. 53 represents the Bones of the Cranium and Face, with a few of the sutures. 1 Frontal bone. 2 Parietal. 3 Temporal. 4 Sphenoidal. 5 Malar. 6 Superior 'maxillary. 7 Nasal. 8 Vertical plate or septum of ethmoid. 9 Lower jaw. 11 Lachrymal bone. 12 Os planum of ethmoid. 13 Super- numerary bone. 14 Incisor teeth. Between 1 and 2, Coronal suture. Be- tween 2 and 3, Squamous suture. GENERAL REMARKS ON THE SKULL. orbital vessels and nerve ; and above this again is the inferior and inner orbitary margin, giving attachment to the levator-labii superioris alasque nasi, and covered by the orbicularis palpebrarum muscle. The malar bone forms the outer boundary of the face ; and the lower jaiu, which projects forward into the chin, and backward and upward into the rami and processes, the inferior boundary. The cavities of the face are the orbits and the nose. The orbits are two hollow cones with their bases in front and their apex behind. The directions of their axes are back- wards and inwards, and, if prolonged, they would inter- sect each other over the sella turcica, forming an angle of about 90 degrees. Seven bones enter into the composition of each orbit. The roof is formed by the orbital processes of the frontal bone and the lesser wing of the sphenoid. The floor is formed by the orbital processes of the superior max- illary bone and of the palate bone, together with a portion of the malar. The outer wall consists of the orbital sur- faces of the greater wing of the sphenoid and malar bones, while the inner wall is composed of the lachrymal, the os- planum of the ethmoid, and part of the sphenoid. Several foramina and openings communicate with the orbit. Behind are the optic foramen, giving entrance to the optic nerve and ophthalmic artery, and the foramen lacerum superius or orbitale, or the sphenoidal fissure, transmitting the third, fourth, first branch of the fifth, and the sixth nerves. At the lower and outer portion of the orbit is the splieno-inaxillary fissure, in which is found the superior max- illary nerve and artery. There are also some small fora- mina penetrating the malar bone. On the inner wall are seen the anterior and posterior ethmoidal foramina — the for- mer giving passage to the nasal branch of the ophthalmic nerve and the anterior ethmoidal artery, the latter to the pos- terior ethmoidal artery. At the inner canthus is the nasal duct, and in the supra-orbital margin the supra-orbital fora- men. The ball of the eye with its muscles, vessels, nerves, and the lachrymal gland and its ducts, are all contained within the orbits. 218 GENERAL REMARKS ON THE SKULL. The nose or nasal fossce are two cavities situated upon either side of the median line, and separated by the vomer and middle septum of the ethmoid. They are bounded ante- riorly and superiorly by the nasal bones , cribriform plate of the ethmoid and sphenoid bones, infer iorly by the palatal processes of the superior maxillary and palate bones, and externally by the nasal processes of the superior maxillary, lachrymal, ethmoid, palate, and inner plate of the pterygoid process of the sphenoid. Each fossa contains three turbinated bones, a superior, middle and inferior, with three corresponding meatuses. FIG. 54. The superior meatus communi- cates with the posterior eth- moidal and sphenoidal cells and the spheno-palatine fora- men. The middle meatus, sit- uated between the upper and lower spongy bones, looks into the antrum, and connects with the anterior ethmoid cells and frontal sinuses. The inferior region or base of the skull is v.ery irregular and reaches from the nasal process of the os frontis to the external occipital protuberance. It is divided into three re- gions, an anterior, middle and posterior. The anterior ex- tends from the superciliary arches of the frontal bone to the pterygoid processes of the sphenoid, and includes the FIG. 54 represents an external view of the Base of the Cranium, aa Hard palate. & Foramen incisivum. c Palate plate of the palate bone, d Point for attachment of azygos uvulae muscle, e Vomer dividing posterior nares. / Internal or pterygoid process, g Pterygoid fossa, h External pterygoid Process, i Temporal fossa, j Cuneiform process of occipital bone, k Fo- ramen magnum. I Foramen ovale. m Foramen spinale. n Glenoid fossa, o Meatus auditorius externus. p. Foramen lacerum anterius. q Foramen caroticum. r Foramen lacerum posterius. s Styloid process, t Stylo mas- toid foramen, u Mastoid process, v Condyles of occipital bone, w Poste- rior condyloid foramen. GENERAL REMAKES ON THE SKULL. 219 nasal spine and orbital plates of the os-frontis, with the inter- nal and external angular processes, and the ethmoid bone. The middle division reaches from the pterygoid to the styloid processes, and includes the pterygoid, azygos, and spinous processes of the sphenoid bone, the glenoid cavities, and petrous points of the temporal, with the cuneiform pro- cess of the occipital bone. In this region are found the foramina ovalia, spinalia, corotica, glenoidea, and auditoria externa. The posterior division reaches from the styloid processes to the external occipital protuberance, and includes the styloid, vaginal processes, the two condyloid, and the two mas toid processes, with their digastric fossa, ihe jugu- lar ridges, the inferior and superior transverse ridges, the protuberance, and the depressions of the occipital bone. The foramina in this division are the foramen magnum, the anterior and posterior condyloid, the stylo-mastoid, the posterior mastoid, the foramen lacerum posterius, and the aqueductus cochlea?. The to? lateral regions are divided each into three por- tions, an anterior or temporal, a middle or squamous, and posterior or mastoid. The temporal division includes the temporal fossa, and is bounded in front by the raaZar bone and the external angular process of the frontal bone ; above by the temporal ridge, and below by the zygomatic arch. The anterior portion of the squamous bone, the greater wing of the sphenoid, the malar, and a part of the frontal, form this division, which is covered by the temporal muscle. The temporal fossa is continuous with the zygomatic, which latter is situated below the zygoma, between the tuberosity of the superior maxillary, and the pterygoid process of the sphenoid, and bounded externally by the zygoma and the ramus of the lower jaw. The zygomatic fossa contains the external pterygoid muscle, a portion of the temporal and internal pterygoid, with the inferior maxillary nerve, in- ternal maxillary artery and branches. The squamous division is formed by the squamous portion of the temporal bone and is covered by the temporal muscle. The mastoid division is posterior, and its most prominent 220 GENERAL REMARKS ON THE SKULL. feature, the mastoid process, has been already noticed in the description of the base. The superior region, or vertex, is smooth and marked off by sutures (Fig. 53,) already detailed. The inner or cerebral surface consists of the arch or vault, and the base. The vault presents along the median line a sulcus for the superior longitudinal sinus. There are also seen grooves for the middle meningeal artery, and depressions for the convo- lutions of the brain. The base has three divisions, an anterior, middle, and posterior. The anterior division includes the crista galli and cribriform plate of the etlimoid bone, the orbital processes of the frontal, and the aloe, minores of the sphenoid. The foramina of this division are the olfactory, foramen ccecum, and the optic. The middle division, called also the middle fossa, is situ- ated between the lesser wings of the sphenoid and the supe- rior ridge of the petrous bone, and bounded laterally by the squamous portion of the temporal. In the centre or on the median line, where the two fossa3 approach, is seen the sella turcica bounded by its four processes, two anterior, and two posterior clinoid — on either side is a groove for the cavernous sinus and carotid artery, and external to this is the middle fossa for lodging the middle lobes of the cere- brum— on the anterior surface of the petrous bone are seen a depression for the Gasserian ganglion, the hiatus Fallopii, and the eminences marking the vertical semi-circular canals. The foramina of this division are the superior lacerated, the rotundum, the ovale, the spinale, the middle lacerated foramen, and the hiatus Fallopii. The posterior division extends from the superior ridge of the petrous bone and posterior clinoid processes, to the trans- verse ridge of the occipital. It includes the posterior sur- face of the petrous bones, on which are seen the internal au- ditory foramina, and the aqueducts of the vestibule. In the middle is the cuneiform process, on either side of and between it and the petrous bone are the posterior lacerated foramina ; GENERAL DEVELOPMENT OF THE SKULL, 221 posterior to the cuneiform process is the foramen magnum, and behind this is the occipital surface which presents two large fossce for lodging the lobes of the cerebellum. These are sepa- rated by a vertical ridge, to which ihefalx minor is attached. Where the vertical and transverse ridges intersect, is seen the internal occipital protuberance, corresponding to the sit- uation of the torcular Heropliili, or the common point of junction of the great sinuses of the brain. On either side of this protuberance is the transverse ridge to which the tentorium is attached, and below and parallel with this ridge is a deep groove which is continued along the inferior angles of the parietal and the mastoid portion of the temporal bone, and finally end in the foramen lacerum posterius of each side. This groove conducts the lateral sinuses out of the brain, GENERAL DEVELOPMENT OF THE SKULL. In the foetus, the upper part of the face decidedly pre- dominates, in consequence of the early development of the frontal bone. The middle portion or upper jaw is, on the other hand, very small from the absence of the maxillary sinus — so that the floor of the orbit and the alveolar arch almost meet. The alveolar border is prominent, owing to the presence of the germs of the teeth. The lower portion of the face, consisting of the lower jaw, is also, at this period, contracted in its vertical diam- eter, and like the upper maxilla, from the presence of teeth germs, presents a similar prominence in its alveolar arch. The ethmoid bone is also, at this period, little developed in height. The transverse diameter of the face, on a line with the orbits, is great ; at the lower part, small. In the adult, the maxillary sinuses being developed, and the alveolar arches being widened and extended, give the face the characteristic expression of this period of life; while in the aged, the loss of the alveolar processes and teeth brings back again the face in a great measure to the foetal condition. These remarks apply mostly to the ante- rior face. The posterior or guttural portion in the foetus and 222 ACTIVE ORGANS OP THE HEAD. infant lias the rami of the lower jaw very oblique instead of vertical, as in the adult. The posterior nares and the pterygoid processes look also obliquely forward and down- ward, while in the adult they become vertical by the de- velopment of the maxillary sinuses, carrying them back- wards. The palatine region, from the same want of de- velopment in the maxillary sinus and forward obliquity of the pterygoid processes, is much shorter from before back- wards, than in the adult. It is thus seen how much the configuration of the face depends on the presence, absence, or partial development of these sinuses. The cranium is remarkable for its early ossification, which commences first in the vault, though at birth it is found more advanced in the base. Indeed, at this period, the base is firm and immovable, while the vault has its bones separated by intervening membranes, which allow of con- siderable movement, so much so that during labor there is always more or less overlapping of the bones. It is at this period the anterior and posterior openings in the cranium, called fontanelles, are seen. CHAPTEK II. ACTIVE ORGANS OF THE HEAD. THESE organs include — 1. Organs of Digestion. 2. Organs of Expression and Speech. 3. Organs of Sense, including the Nerves. 4. Organs of Circulation. 5. The Fascia. The organs of digestion comprise those of — 1. Prehension, 3. Insalivation, 2. Mastication, 4. Deglutition, ORGANS OF PREHENSION. 223 which, constitute the mouth. The mouth contains the den- tal organs, and has its superior wall or roof formed by the palatine processes of the superior maxillary and palate bones. Its floor consists of the mylo-hyoid muscles. The lips bound it in front, the soft palate behind, and the cheeks laterally. SECTION I. ORGANS OF PREHENSION, WHICH CONSIST OF THE MUSCLES OF THE MOUTH. Dissection. — To expose the muscles of prehension, com- mence the first incision at the meatus externus of the ear, carrying it along the zygoma to the external canthus of the eye; thence round the lower margin of the orbit to the inner canthus, and up to the nasal spine of the os-frontis; from this continue the incision along the median line of the nose to its tip, thence down to the margin of the upper lip; from this continue round the margin and angle of the mouth to the middle of the lower FIG. 55. lip; thence down to the lower margin of the chin; and thence along the sides and up the rami of the lower jaw, back to the place of beginning. Make a sec- ond incision from the promi- nence of the malar bone to the angle of the mouth. Turn the' integuments from the ear to- wards the mouth. Hold the skin tense, and always dissect in the course of, and close to, the fibres of the muscle. The FIG. 55 represents a front view of the Muscles of the Face, a a Anterior bellies of the occipito-frontalis. 6 6 Orbicularis palpebrarum. c Fyramidales nasi. d Compressor nasi. e e ff Levator labii-superioris-alaeque 'nasi. g g Zygomaticus minor, hh Zygomaticus major, ti Masseter. jj Buccinator or trumpeter's muscle, k k Orbicularis oris. 1 1 Depressor-labii-inferioris. m Levator menti. n n Depressor-anguli oris. o o Levator-anguli-oris. 224 ORGANS OE PREHENSION. cavity of the mouth, should first be filled with baked hair or tow, (soft paper will answer,) and then sewed up. Levator Idbii superioris alceque nasi (Fig. 55) is a trian- gular and thin muscle, situated between the orbit and upper lip, and lying on the side of the nose. It arises by two heads, one from the nasal process of the superior maxillary bone, the other broad from the orbitary margin above the infra-orbi- tal foramen; its fibres descend and are inserted into the ala nasi and upper lip. Its function is to elevate the ala and upper lip. Its superior portion is covered by the orbicularis palpebrarum, and its orbital division is, by some, made a distinct muscle, and called the levator labii superioris proprius. Depressor labii superioris alceque nasi is a small muscle situated on either side of the frenum, and is seen by raising the upper lip, and lifting the mucous membrane. It arises from the surface in front of the alveoli of the incisor and canine teeth, and ascends to be inserted into the upper lip and ala of the nose. It lies upon the bone, and is covered by the levator labii superioris alwque nasi and the orbicularis vris. Its function is to depress the upper lip and ala nasi, and antagonize the levator. Levator anguli oris (musculus caninus) is seen by raising the levator labii superioris alaaque nasi which covers it It arises from the canine fossa of the superior maxillary below the infra-orbital foramen, having the infra-orbitar nerves and vessels ramifying on its anterior surface. It descends and is inserted into the angle of the mouth, inter- mingling its fibres with those of the orbicularis, depres- sor anguli oris, and zygomatic muscles. Its function is to elevate the angle of the mouth. Depressor anguli oris (or triangularis oris) is a triangu- lar, flat muscle, having its base below and apex above. It arises fleshy and broad from the external oblique ridge of the lower jaw, ascends converging, and is inserted into the angle of the mouth, where its fibres blend with the levator anguli, orbicularis, and zygomatic. Its function is to de- ORGANS OF PREHENSION. 225 press the angle of the mouth, and antagonize the leva- tor. Levator Idbii inferioris (or menti) is seen by turning down the lower lip and lifting the mucous membrane. It arises, on either side of the frenum, from the surface in front of the alveoli of the incisor teeth of the lower jaw; its fibres descend and are inserted into the integument of the chin. Its function is to elevate the chin and lower lip. Depressor labii inferioris (quadratics menti) is a broad muscle intermixed with fat, and situated upon either side of the symphysis. It arises from the side and front of the inferior maxilla at its base, and is inserted into the greater part of the lower lip and orbicularis muscle. Its function is to depress the lower lip. Zygomaticus major is a long, slender muscle, and arises from the malar bone near the zygomatic suture. It is in- serted into the angle of the mouth. Its function is to draw the mouth upwards and backwards, as in smiling. Zygomaticus minor is very small. It arises from the malar prominence, and is inserted into the upper lip near the angle. This muscle is sometimes wanting, and some- times it is simply a slip of the orbicularis palpebrarum by which its origin is covered. Its function is the same as that of the zygomaticus major. Both these muscles blend with the others which are inserted into the angle of the mouth. Buccinator (fiovxavov, a trumpet,) is situated at the side of the face, between the upper and lower jaws. It is a thin and broad sheet of muscle, the fibres of which run horizon- tally, and arise from the alveoli of the last molar teeth of the upper jaw, as far back as the pterygoid processes; from the external oblique ridge of the lower jaw, as far back as the coronoid process, and from the pterygo-maxillary liga- ment. It is inserted into the angle of the mouth and blends with all the other muscles inserted here. Its function is to retract the lips, to diminish the cavity of the mouth by drawing the cheek to the teeth, thus aiding in mastication; and to assist to puff out the cheek, as in filling wind instru- ments. It is covered by a quantity of fat, found in soft, 15 226 BLOOD VESSELS SUPPLYING THE ORGANS OF PREHENSION, round masses, which separates it from the masseter muscle and ramus of the lower jaw, and by the zygomatic, the levator, and depressor anguli-oris muscles, together with the facial nerves and vessels which ramify over its surface. The duct of Steno is seen passing through this muscle at its upper part, opposite the second molar tooth of the upper jaw. Orbicularis-oris consists of two semi-circular fleshy planes, surrounding the mouth, intersecting each other at the an- gles, and blending with all the muscles already described. It has one leading peculiarity in having no bony origin or insertion. Its function is to close the mouth and antagonize all the muscles inserted into its angles. This muscle con- stitutes the chief thickness of the lips, and is intermixed with small granulated particles of fat. COMBINED ACTION OF MUSCLES. The separate action of the several muscles concerned in prehension, is, as we have seen, to elevate, depress, re- tract, and close the lips ; while in their conjoint and har- monious action, they either act separately or together, or in whatever way may best accomplish the great end for which they were designed. They are also engaged in other functions, as speaking, breathing and mastication. BLOOD VESSELS SUPPLYING THE ORGANS OF PREHENSION. 1. Facial Artery. 2. Infra Orbitar. 3. Transverse Facial. The Facial Artery (Fig. 73) arises from the external carotid, at its front part, above the lingual, and ascends to the submaxillary gland behind, by which it is covered. It now curves over the base of the lower jaw, anterior to the masseter muscle, ascends to the commissure of the lips, thence by the side of the nose to the angle of the eye, where it terminates by anastomosing with the ophthalmic. Its whole course is very tortuous, to adapt it to the various movements of the jaws. Its branches are, the inferior palatine, submaxillary, THE TEETH. 227 submental, pterygoid and masseteric, inferior labial, infe- rior coronary, superior coronary, later alis nasi, and angular. Of these branches, the latter are mostly concerned in nour- ishing the organs of prehension. The inferior labial sup- plies the skin and muscles of the lower lip. The inferior coronary, leaving the facial at some distance from the angle of the mouth, proceeds along the border of the lower lip, and unites with its fellow of the opposite side. The superior coronary pursues a similar course along the border of the upper lip, uniting with its fellow and send- ing a branch to the septum nasi. The lateralis nasi, and the angular termination of the facial, supply the ala and dorsum of the nose and the angle of the eye. The Infra-orbital is a branch of the internal maxillary, which, passing along the infra-orbital canal, comes out at the infra-orbital foramen, supplying the muscles of the upper lip, and anastomosing witli the facial, transverse facial, alveolar, buccal and ophthalmic arteries. The Transverse facial (trans vers alis faciei) comes from the external carotid in the substance of the parotid gland ; sometimes it is a branch of the temporal ; it runs parallel to the duct of Steno, crossing the masseter muscle, supply- ing the lateral parts of the mouth, and anastomosing with the facial and infra-orbital arteries. The Veins correspond to the arteries and terminate in the internal jugular. The Nerves of Prehension (Figs. 74, 97) belong to the 5th and 7th pair, which will be described under the heads of organs of mastication and expression. SECTION II. ORGANS OF MASTICATION. These organs are divided into the passive and active. The passive organs of mastication are THE TEETH. The teeth constitute the immediate agents in mastica- tion, are the hardest portions of the body, and form an 228 THE TEETH. essential element in the classification of the animal king- dom. They occupy the alveolar cavities of the superior and inferior maxillary bones, and are fixed firmly in their respective situations by a species of articulation called gomphosis (70^05, a nail,) from the supposed resemblance to the manner in which a nail is confined when driven into a board, as seen in Fig. 56. The teeth in both jaws are arranged in what have been called the dental arches. The size of the arches in the two jaws differs; that of the upper closes over the incisors and canine of the lower, and thus forms the segment of a larger circle — this overlapping in the two arches illustrates their adaptation to the cutting action ; and they have been com- pared to the blades of a pair of scissors. The molars, which come in contact by the superior surface of their crowns, have that position which is best adapted for the grinding and pounding motions. Fig. 75, from Nasmyth, illus- trates the superior dental arch of man ; and the same figure shows the superior arch of a chimpanzee. This latter pre- sents a marked difference from the human arch, in having its lateral portions straight, and in presenting a space between the lateral incisor and canine. The teeth have two grand divisions : First, the Temporary; Second, the Permanent. The first division has 20 teeth; the second 32. Each division is classified into, 1. Incisors — (incisores.) 2. Canines — (cuspidati.) 3. Bicuspids — (bi-cuspidati.) 4. Molars — (molares.) THE TEETH. 229 FIG. 57. Description of a Tooth. — Each tooth consists of a crown, neck, and root or fang. The crown is external, naked,'has no investment of periosteum like the bones, hut is covered by a substance called enamel. The neck is the contracted portion of the tooth, surrounded by the gum; while the root, firmly fixed in the alveolar walls, is covered by the periosteum reflected from the alveoli, and has its apex perforated for the entrance of a nerve and artery. Description of each class of Teeth, beginning with the permanent division. The Incisors (incido, to cut,) are sit- uated in the anterior and central alveoli of the upper and lower jaw. They are four in number in each jaw — two central and two lat- eral. The crown of each is wedge-shaped and sharp, smooth and con- vex in front, concave be-j hind, and covered with a thick coating of enamel. The cutting edge is the, widestpart, and continues narrowing to the extremi- ty of the fang. The root has a conical form — is single, and flattened on its side, and has an opening at its apex for the passage of the vessel and nerve to the pulp. Those of the upper jaw are larger and stronger than those of the lower. The central incisors of the upper jaw are larger than the lat- eral; while in the lower, the lateral are larger than the central, though the difference is slight. The superior central incisors are the Iroadest of all t*he front teeth, measuring about four lines in their crowns. The inferior central incisors are, on the contrary, the small- est, measuring only about two lines and a half. FIG. 57, a a a a Anterior view of the Incisors ; 6 6 6 b Posterior view ; « c c c Lateral view. 230 THE TEETH. The superior central incisors are the longest of all the front teeth except the canine, being found to have an aver- age measurement in length of about twelve lines; while the inferior central incisors are but ten lines long, and are the shortest of all the teeth. The relative length of the crown and root, though subject to variation, is nearly equal in the upper central incisors, while in the inferior central incisors four lines are assigned to the crown and six to the root. For the lateral incisors of both jaws, four lines and a half for the crown and seven for .the root are regarded as the fair relative average length. The anterior surface of the central incisors is frequently marked by longitudinal ridges, which in early life are found to terminate in small cusps upon the cutting edge of these teeth — three of these cusps are seen on the central, and but one on the lateral in- cisor. This serrated provision in the incisors is believed to be nicely adapted to the division of the food, and designed to compensate for the weak condition of the dental system and its muscular powers at this early period. As the per- manent teeth advance these cusps disappear. On the posterior surface of the superior central incisors, which have been stated to be concave, and receive the crowns of the lower incisors at an acute angle, raised un- dulations are described to exist in early life, and are re- garded as assisting in the mastication of the food at this time, when the molars are imperfect. Professor Harris describes four surfaces to the crown of an incisor, which he thus characterizes: two approxirnal, one labial, and one palatine or lingual surface; also four angles, a right and left labio-approximal, and right and left palato-approximal, or lingua-approximal. Canine, or Guspidati — (cuspis, a point.) The canine teeth are two in each jaw, and situated one upon either side of the lateral, and with the incisors complete the range of •what are called the oral teeth. They particularly distin- guish the carniverous animals, and are designed to tear and rend the food, whilst the incisors simply cut. The crown is conical, and has its anterior surface more con- THE TEETH. 231 FIG. 58. FIG. 59. vex than the incisors, and the posterior more irregular, and possessing a larger tubercle near the neck. The roots are the longest of all the teeth — larger than the incisors; single, but marked by a groove, showing an attempt towards the double root The roots of the upper canines are seen to extend into the nasal process of the superior maxilla, above the floor of the nostrils — and those of the lower are found to descend about one half of the depth of the lower jaw, and to be mid- way between the anterior mental fora- men and the symphy-sis menti. The supe- rior edge of the upper canine is greater than that of the lower, the former being estimated at about four lines, the latter about three and a half. The upper canine is larger than the lower, mea- suring about thirteen lines — to the crown is given six lines for its length, and to the root seven lines. The root is not unfrequently found curved or undulating. The canine presents on the middle of its anterior surface a ridge which ends on the summit in a cusp. On either side of this middle ridge, two other ridges are seen but not ter- FIG. 58, a a View of the Cuspids, or canine, from before; b b View of the same from behind ; c c Side view. FIG. 59, aaaa View of the Bi-cuspids from without; b b b b View from within ; c c c c Side view. 232 THE TEETH. minating in cusps. On the posterior surface "undulating ridges," running transversely, are seen, but more distinct in the upper than in the lower canines. The summits of the canines are tubercular and oblique, and their cusps disappear in the adult. Ei-Cusplds (Bi-Cuspidati — Fig. 59.) — The bi-cuspids are upon either side of the canines, and are four in each jaw ; they are intermediate in size between the canines and mo- lars, and derive their name from having two tubercles on their grinding surfaces. A groove running in the direction of the alveolar arch separates these tubercles; the outer is larger than the inner, and those of the upper larger than those of the lower jaw. The body is thicker, and the sides are flatter, than either the incisors or cuspidati. Their roots are single, though the groove is much deeper than the canine, and often divides it into two. The necks of the bi-cuspids are smaller, in proportion to their crowns, than those of any other teeth ; hence the necessity of using more caution in their extraction, as they are more liable to fracture. Professor Harris gives a bi-cuspis five surfaces, two ap- proximalj one buccal, one palatine or lingual, and a grinding surface; also four angles, one anterior, and one posterior palato-approximal, and one anterior, and one posterior bucco-approximal. MolareSj or Multi-Cuspidati. — The posterior teeth in the alveolar arch of each jaw constitute the true molars or grinders, and with the bicuspids form what is called the buccal range. There are six to each jaw, three upon either side behind the bicuspids. Their greater size distinguishes them. The crown of each presents a square form, and has on the grinding surface four and five tubercles, with as many depressions, which are so arranged that the tuber- cles of either jaw are adapted to corresponding depressions in the other. There are three roots, and sometimes four, to the upper molars; two of these roots are external, nearly parallel and vertical. The third is internal, directed to the roof of the THE TEETH. 233 mouth, and forms an acute angle with the other. The mo- lars of the lower jaw have but two roots, the one anterior, the other posterior; they are flattened very much laterally, grooved, and sometimes bifid. The first molar is the largest, the third or last, called dens sapientice} is the smallest and shortest. The wisdom tooth of the upper jaw has its roots sometimes united into one, while the root of the lower is FIG. 60. conical and generally single. The roots of the first two I upper molars are situated be- neath the floor of the antrum, and occasionally perforate this cavity. Those of the last inferior molars are found in the base of the coronoid pro- cesses. The apex of all the roots are perforated for the trans- mission of vessels and nerves. The roots of the molar teeth in both jaws are found not unfrequently to approach each other, and thus enclose the osseous wall which divides them. From this arrangement they offer considerable difficulty to extraction. The inter- FIG. 60, a a a a a a Exterior view of the molars, b b I b I b Interior view, c c c c c c Lateral view. 234 THE TEETH. nal root of the upper molar is seen sometimes to be joined by a " broad plate" to the anterior external, and then again all three have been found united in one mass. The roots of the lower molars are seen occasionally to be sim- ilarly connected. And, indeed, so great is this irregularity in the roots of the molars, as to length, figure and direc- tion, that, according to Mr. Nasmyth, it is impossible to tell beforehand the amount of resistance to be encountered in their removal. The average length of a molar he esti- mates at from eight to thirteen lines. In reference to the function of the molars, this same gentleman uses the following language: "The mechanical disposition of the molar teeth is beautifully fitted to the purposes which these organs have to fulfil; for example, the first act of mastication, consisting in the closure of the lower against the upper jaw, while it secures the food, makes its greatest force of pressure against the outer limb of the crown of the superior molars, that limb which we know to be supported by two out of the three roots of the tooth. "Again, when trituration ensues, the ramus of the jaw is drawn inwards, and the chief amount of pressure is trans- ferred to the outer limb of the lower molars, where the greatest strength of fang exists." Structure. — The structure of each tooth consists essential- ly of three parts, the pulp, dentine or ivory, and enamel, to which the cementum or crusta-petrosa is added, (Fig. 61, A.) Each tooth contains within itself a cavity for lodging the pulp, called the pulp cavity, (Fig. 61, B, C.) The shape of the cavity corresponds to that of the tooth to which it belongs. The dental pulp has the same form as the cavity, and is de- scribed by Mr. Thos. Bell, as " very soft, gelatinous, and semi-transparent, and having its surface covered by an ex- tremely delicate, thin, vascular membrane, closely attached to it by vessels." The vessels (Fig. 62, from a drawing by Mr. Nasmyth) which supply the pulp, enter the tooth at the apex of its root, forming a capillary net-work on the pulp, and show THE TEETII. 235 FIG. 61. the great vascular- ity of this tissue; the larger vessels are deep, and run tortuously in the longitudinal direc- tion; the arteries and veins commu- nicate by an im- mense number of looped capillaries, as seen in the drawing. The nerves of the pulp (Fig. 63, taken also from Mr. Nasmyth) come from the superior and inferior maxillary divisions of the fifth, accompany the artery, and are seen to form a series of loops. The pulp thus seems to be consti- tuted of blood vessels and nerves, surrounded by a very delicate membrane. FIG. 61, A represents the different structures composing a tooth, a Pulp. 6 Dentine, c Enamel, d Crusta-petrosa, or cementum. FIG. 61, B represents the pulp cavities of the permanent teeth from vertical sections. FIG. 61, C represents thepuJp cavities of the permanent teeth of both jaws, from transverse sections at their necks. 236 MICROSCOPIC ANATOMY OF THE PULP. MICROSCOPIC ANATOMY OF THE PULP. FIG. 62. FlG 63. According to the mi- croscopic observations of Mr. Nasmyth, the pulp consists of a structure essentially cellular, (as exhibited in Fig. 64, A.) which he calls the ret- icular tissue. These cells constitute the "principal FIG. 62 represents the vascularity of the pulps of one of the central incisor teeth of the upper jaw. The deeper vessels are seen to be large, and the looped communication between the capillary arteries and veins is distinctly shown. The small figure shows the pulp of natural size. FIG. 63 represents the pulp of an adult bi-cuspid, and the arrangment of its nerves— magnified twenty times. MICROSCOPIC ANATOMY OF THE PULP. 23T portion" of the bulk of the tooth. They vary very much in size and shape, being estimated from the ten-thousandth to the one-eighth part of an inch in diameter. They are disposed throughout the pulp in concentric layers, and have granules interspersed among them. The microscope of this gentleman also shows the pulp cells to consist of a membrane, cavity and nucleus. The nucleus generally occupies the lateral portion of the cell- wall, though some- times found in the centre of its cavity. The nuclei of all the cells are compo- sed of animal tissue, and remain as such without any trans- formation ; while the cells themselves un- dergo a "conversion" into ivory, by the deposition in their interior of calcareous salts. The nuclei, arranged in a "linear succession," constitute "the fibres of the ivory," FIG. 64, A, the Cellular arrangement in a portion of the body of the pulp. FIG. 64, B represents the presence of Vesicles on the superficial layer of the pulp — not an unfrequent occurrence according to Mr. Nasmyth. FIG. 64, C, another variety in the arrangement of the Cells of the pulp. FIG. 65, A represents the baccated or beaded appearance of Dentine, accord- ing to Mr. Nasmyth. FIG. 65, B represents a portion of the Pulp, as well as the ivory, and shows the fibres to be continuous with the parietes of the cells. 238 DENTINE OR IVORY. and are imbedded in the osseous substance. These fibres are solid, instead of tubular as supposed by Ketzius and others, — and they present (from the peculiar arrangement of their nuclei) a beaded or "baccated" appearance — as seen in Fig. 65, A. The fibres of the pulp are observed to be spiral in their course, but less so, and rather undulating where the ivory is deposited around them. The pulp is enclosed in a double sac — the outer one stated by Mr. Hunter to be "soft, spongy, and without vessels," while the inner is very' vascular and firm. Mr. Blake on the other hand makes the outer to be full of vessels, as well as spongy, and the inner to be destitute and delicate. The injections of Mr. Fox, preparations of Mr. Bell, and observations of Pro- fessor Harris, all seem to show that both membranes are decidedly vascular. At an early period when this sac, termed the dental capsule, is about to close its follicular stage, from being a mucous membrane, presents, according to Mr. Nasmyth, a "white, silvery, loose, and rugous" appearance, which, under the microscope, exhibits minute cells differing from those of the epithelium, while the inter- nal layer of the sac, according to this same authority, pre- sents layers of loose cells, of oval shape, containing nuclei and some granular matter, but destitute of vessels. This layer, however, he states, has beneath it a net-work of vessels, "supported by a web of areolo-fibrous tissue/' which readily accounts for both layers of the capsule being considered vascular. The dental capsule is found to be connected with the alveolar periosteum, and so blended with it, as to be con- sidered a single membrane. Mr. Bell makes one of its attachments inseparable from the gums, and the other con- nected with the pulp, where the vessels and nerves enter. DENTINE OR IVORY. Dentine or Ivory, (see Fig. 61, A,) forms by far the most abundant constituent of a tooth, composing the whole of the body, root and neck, excepting the thin cov- DENTINE OR IVORY. 239 ering of enamel, the crusta petrosa, and pulp. Its color is a yellowish white, and presents when broken a fibrous appearance. It is harder than bone. Chemical analysis makes ivory to consist, in 100 parts, of Phosphate of lime, 61.95 Fluate of lime, 2.10 Carbonate of lime, 5.30 Phosphate of magnesia, 1.25 Soda and chloride of sodium, 1.40 Cartilage and water, 28.00 According to Mr. Nasmyth, ivory presents three varieties. The first, consisting of a " regular series of fibres and cells," called Jibro-cellular, and regarded as the most perfect kind of ivory, forms the greater portion of the teeth of man, and is found to strongly characterize both classes of the mam- malia and reptilia. The second variety of ivory presents vertical canals traversing it, as seen particularly in the teeth of fish, and is called canalicular. The third variety, from exhibiting, like bone, little corpuscular bodies scat- tered through its substance, receives the name of corpus- cular ivory. Specimens of this latter are noticed in the teeth of the walrus, sloth, &c., and is stated to exist in the human tooth, sometimes, when diseased. The structure of the dentine, and its relation to the pulp, are seen in Fig. 61, A, after Ketzius; here the fibres are rep- resented as tubular, the tubes or dental canals opening by circular orifices in the pulp cavity, from which they traverse the body of the tooth, in a curvilinear direction, to end in cul de sacs at the outer margin of the dentine, or at the enamel. These tubes are represented as having distinct parietes, branching in their course, some bifurcating at their termination, others at their middle, and containing a serous fluid, which is supposed to be intended for the nour- ishment of the tooth, by imbibition. It appears from Mr. Nasmyth's later experiments that the structure of dentine is, like that of the pulp, essentially cellular and. fibrous — that is, consisting of cells and fibres — and that these cells assume 240 BLOOD-VESSELS OF IVORY OR DENTINE. different shapes in different ani- FIG. 66. .111 mals, so much so, indeed, as to be regarded an important feature in the classification of the animal kingdom. But notwithstanding the difference in shape, in the \ ivory cells of different animals, they all nevertheless have one character in common, i. e. their baccated (or headed) appearance as seen in Fig. 65, A. The beads represent the nuclei of the differ- ent cells, which, as before stated, consist of animal tissue, remain as such, and, connected in a lin- ear series, constitute the fibres of the ivory, — while around the fibres, and within the cells, is deposited the calcareous matter, giving hardness, density, and strength to the ivory. The fibres themselves are also found to be solid, instead of tubular as Ket- zius thought, and the interfi- brous substance, instead of being structureless, to consist of organized cells. BLOOD-VESSELS OF DENTINE OR IVORY. The vascularity of dentine is generally denied by anat- omists; but Fig. 66, taken from an injected specimen in the possession of Professor Harris_, seems clearly to show it has a circulation, and in his Principles and Practice of Dental Surgery, he states that similar specimens are in the possession of Dr. Maynard. In vol. 2 of the American Journal of Dental Science, the doctor uses the following language in explanation of the above figure, "the second time he had the good fortune to make this discovery, it was in the half of an inferior molaris, taken from the FORMATION OF DENTINE. 241 mouth of a boy eleven years of age, and of which an exact representation of a microscopic view of it is annexed. (Fig. 66.) The tooth had ached violently for several days pre- vious to its extraction, from which circumstance he was induced to believe that the vessels of the pulp were highly injected, and to satisfy himself upon the subject, he soon after its removal split it open with a strong pair of ex- cising forceps. As was anticipated, the vessels of the pulp were filled with red blood, and on examining the half of the tooth in which this had remained, through a micro- scope, a number of vessels within the very substance of the bone, charged with this fluid, were distinctly seen." The crown is represented as decayed. Formation of the Dentine. — The ossification of a tooth, it is well known, commences on the surface of the pulp, and according to the experiments of Mr. Hunter, from feeding animals on madder, this ossific matter is laid layer within layer, from the surface to the centre, till the tooth is com- pleted, the pulp retiring and diminishing as ossification advances. The incisors begin to ossify by three points, the cuspids by one, the bicuspids by two, and the molars by three, four, or five, according to the number of projections or tubercles upon their grinding surface. The crown of the tooth being formed, the roots are next observed to be de- veloped, and their number always previously indicated by the number of distinct vessels and nerves going to the pulp. This view of the formation of dentine has been termed the excretion theory. The later researches of Mr. Nasmyth give another view of the subject ; observing the similarity of structure between the pulp and dentine, that each pos- sessed the cellular or reticular arrangement, (in his own comprehensive language) he remarks, u My theory, indeed, is most simple, the cells of the pulp are converted into ivory cells by the deposition within them of earthy salts, and the cells so converted, with their nuclei, are the perfect ivory ; moreover, the nuclei assume a peculiar arrange- 16 242 THE ENAMEL. ment and constitute the structure which I have described and demonstrated by the name of baccated fibre." See Fig. 65, A. FIG. 67. ABC Mr. Tomes makes three stages in the formation of den- tine or ivory. 1st. The Areolar, consisting of a very fine tissue, which he calls the preparatory stage. 2d. Cellular, (Fig. 6I7, A,) in which the cells are scattered irregularly and have no definite arrangement. 3d. The Linear, where the cells (Fig. 67, B) are disposed in regular rows, vertical to the coronal surface. From this third stage, Mr. Tomes thinks, the regular, continuous, permanent tubes of dentine re- sult— these vertical cells becoming united, end to end, opening into each other and forming a communication : so that if the baccated appearance of Mr. Nasmyth is seen, it is regarded as an arrest of development, and exhibiting dentine in an imperfect state. The Enamel (Fig. 61, A) covers the crown of the tooth ; is thickest upon the cutting and grinding surfaces, and is much the hardest portion. Its hardness is so great as to strike fire with steel, and resist the file or saw ; hence it is well suited to oppose the pressure and friction to which it is constantly liable. Its color is a pearly white, and it is very brittle. It is found to consist of fibres, or minute FIG. 67, A represents the Dentine in its second stage. FIG. 67, B represents the Dentine in the early part of the third stage. FIG. 67, C represents the Dentine at the completion of the third and most perfect stage. CRUSTA-PETROSA OR CEMENTUM. 243 hexagonal prisms, arranged perpendicularly to the surface of the ivory parallel to each other, and having one of their extremities resting upon the ivory, and the other forming the free surface of the crown, as seen in Fig. 68, A. A thin membrane is described as separating the enamel from the ivory, and is found, by Mr. Nasmyth, to be composed of cells. The enamel, like ivory, consists also of animal and earthy matter, and is chemically composed, according to Berzelius, in 100 parts;j, the ear,) arise low down in the neck at its base. The right common ca- rotid comes from the arteria innominata, the left from the arch of the aorta. Both ascend the neck, covered first by iheplatysma and superficial fascia, along the inner margin of the sterno-cleido mastoid muscles, to the top of the thyroid cartilage, where, as we have just stated, they divide into the external and internal carotids. 260 BLOOD-VESSEL OF THE TEETH. FlG- 73t A The external gives off several branches. The in- ternal maxillary, however, is the only one claiming attention in the present place. To expose this ves- sel, the zygomatic arch should be sawn through at each end, and turned down. The temporal mus- cle is to be divided at its insertion into the coronoid process, and turned up. The ramus of the jaw di- vided in its middle, disar- ticulated and removed, the vessel is now brought to view. It will be seen to com- mence in the substance of the parotid gland, near the meatus externus, to pass obliquely forwards behind the neck of the lower jaw; then between the two pter- yyoid muscles, often winding round the out- er surface of the external pterygoid at its origin. From this it proceeds to the tuberosity of the superior maxilla, and finally bends down into the pterygo maxillary fossa, to FIG. 73, A represents the arteries supplying one side of the face and mouth. 1 1 External carotid artery. 2 Inferior maxilla with its exterior wall re- moved, so as to expose the inferior dental artery, and roots of the teeth. BLOOD-VESSELS OF THE TEETH. 261 terminate by sending off several brandies. Its branches supplying the teeth are, 1. The superior dental or alveolar. 2. Infra orbitar. 3. Inferior dental or maxillary. The superior dental artery comes off from the internal maxillary, at its entrance into ihepterygo maxillary fossa; it then winds round the maxillary tuberosity, sending branches through the posterior dental canals to supply the molares and the antrum, and finally proceeds forward upon the alveolar processes, supplying their cavities, and the gums. Those branches going to the teeth enter by the foramen at the apex of the roots, and are distributed over the pulps. The infra-orbital artery arises from the internal maxil- lary in the upper part of the pterygo maxillary fossa, enters the infra orbital canal, traverses its whole extent along with a nerve of the same name, and emerges upon the 3 Posterior mental foramen, which gives passage to the inferior dental artery. 4 Anterior mental foramen, where the same artery makes its exit. 5 5 The anterior and inferior wall of the superior maxilla removed, so as to exhibit the antrum, roots of the teeth, and arteries supplying each. 6 Infra-orbitar foramen, for the passage of the infra-orbitar vessels. 8 Nasal process of su- perior maxilla. 9 Pterygoideus intejnus muscle. 10 Angle of inferior max- illary bone. 11 Orbit of the eye. 12 Superior thyroid artery. 13 13 Facial artery. 14 Terminating branch of the lingual. 15 Where the external carotid terminates by dividing into the internal maxillary and temporal. 16 Temporal artery. 17 Internal maxillary. 18 18 Inferior dental artery. 19 Deep temporal branch. 20 Transverse artery of the face. 2121 Muscular branches. 22 Alve- olar branch. 23 Posterior dental branch. 24 Where the infra orbital artery terminates. 25 Nasal branch of the facial. 26 Sub-mental branch. FIG. 73, B represents chiefly the external carotid artery, and its branches which supply the exterior head, face, and part of the neck. 1 Common ca- rotid artery. 2 External carotid. 3 Internal carotid. 4 Superior thyroid. 5 Lingual. 6 Facial branches of external carotid. 7 Sub-mental. 8 Inferior coronary. 9 Superior coronary branches of facial. 10 Occipital. 11 Infe- rior pharyngeal branches of external carotid. 12 12 13 Branches of occipital. 14 Posterior-auricular branch of external carotid. 15 Transverse facial. 16 Posterior temporal. 17 Middle temporal. 18 Anterior temporal branches of the temporal artery. 19 Supra orbitar, a branch of the ophthalmic. 20 Sub- clavian, a branch of the arteria innominata on the right, and the aorta on the left. 262 BLOOD-VESSELS OF THE TEETH. face at the infra orbital foramen, anastomosing with the facial and transverse facial arteries. Just before it emerges, it sends down, in the anterior dental canal, a branch to supply the incisors and cuspidati, and also the lining membrane of the antrum. The inferior dental arises from the internal maxillary behind the neck of the lower jaw, descends to the poste- rior mental foramen, which it enters along with the dental nerve; thence it passes along the canal beneath the roots of the teeth, sending up into each, in its course, small twigs which supply the molars. When opposite the bicus- pid, it divides into two branches — the one being the con- tinued trunk which proceeds forwards to the symphysis, supplying the anterior teeth, while the second branch passes out at the anterior mental foramen, upon the side and front of the chin, anastomosing with branches of the facial artery. The internal maxillary vein, made up of the veins corre- sponding to the several branches of the internal maxillary artery, returns the blood of the artery, and passing behind the neck of the jaw, unites in the substance of the parotid with the temporal vein — the junction of the two mainly forming the external jugular, which passes superficially down the neck, to terminate in the subclavian vein. THE NERVES OF THE TEETH. (Fig. *74.) The nerves supplying the teeth come from the fifth pair, and are nerves of sensation. The fifth nerve can be traced to the spinal cord, having its roots in the anterior and pos- terior columns ; hence it is called the cranial-spinal nerve. Being a spinal nerve, it has on its posterior root a ganglion, and the junction of the anterior and posterior roots consti- tutes properly the fifth nerve. It is seen to emerge at the .side of the Pons-varolii on the anterior part of the cms- cerebelli. At this point it is composed of from 80 to 100 filaments, which pass forward in a canal of the dura-mater upon the anterior surface of the petrous bone, in a depres- sion of which it expands into a ganglion called the Gasse- THE NERVES OF THE TEETH. 263 rian ganglion. On the under surface of this ganglion is seen the anterior root, having no connection with it and being the motor portion. From the gasserian ganglion proceed three branches, 1. The ophthalmic, 2. The superior maxillary, 3. The inferior maxillary nerve. FIG. 74. The two latter furnish the branches supplying the teeth. The superior maxillary nerve arises from the middle of the ganglion of Gasser, passes forwards through the fora- men rotundum of the sphenoid bone, into the pterygo-max- illary fossa — at this point it sends off several branches, two of which descend to join the ganglion of Meckel. The main trunk is continued for- ward with the artery in the infra orbital canal, as the in- fra orbital nerve} and finally emerges at the infra orbital foramen between the levator labii superioris alasque nasi, and levator anguli oris muscles, anastomosing with the nasal branch of the ophthalmic, and the portio-dura of FIG. 74 represents the distribution of the fifth pair, or Trifacial Nerve, and especially those branches supplying the teeth. 1 Orbit ; 2 Maxillary sinus, or antrum of Highmore ; 3 Tongue ; 4 Infe- rior maxilla; 5 Root of fifth pair, forming the ganglion of Gasser; 6 Oph- thalmic, or first branch of the fifth ; 7 Superior maxillary, or second branch of the fifth ; 8 Inferior maxillary, or third branch of the fifth ; 9 Frontal branch ; 10 Lachrymal branch; 11 Nasal branch, which latter, with 9 and 10, are branches again of the first or ophthalmic division of the fifth ; 12 Internal nasal nerve going through the anterior ethmoid foramen; 13 Ex- ternal nerve ; 14 External and internal frontal nerve ; 15 Infra orbitar nerve ; 16 Posterior dental nerves; 17 Middle dental branch; 18 Anterior dental 264 THE NERVES OF THE TEETH. the seventh. The infra orbital nerve, just before emerging., sends down in the anterior dental canal , in front of the antrum, the anterior dental nerve, which gives off filaments to supply the incisors, canines, and bicuspids of the upper jaw, as well as the lining membrane of the antrum. These accompany the arterial twigs and enter the apex of the roots in a similar manner. An anastomosis occurs between the anterior and posterior dental nerves. The posterior dental nerves come off from the superior maxillary in the pterygo maxillary fossa; they consist of two or three branches, which enter the posterior dental canals upon the tuberosity of the superior maxillary bone, and supply the molares, the contiguous gums, and buccinator muscle. The superior maxillary nerve is connected with the ganglion of Meckel, called also spheno-palatine, from which three sets of branches are found to proceed — the one pass- ing downwards, the inferior, the second going backwards, the posteriory while the third proceeds inwards, and is the internal set. The ganglion of Meckel is situated in the ptery go-maxil- lary fossa between the pterygoid processes and the tuber- osity of the superior maxilla, surrounded by adipose mat- ter and branches of the internal maxillary artery. The first set of branches, the inferior, proceeding from this ganglion, descend the posterior palatine canal. They are four or five in number and receive the name of the palatine nerves. As they approach the palate they divide into an anterior, posterior, and middle set of filaments; the ante- rior proceeds forwards above the mucous membrane in a groove on the inside of the alveoli, supplying these parts, while the posterior and middle are distributed to the soft- palate, tonsils, and uvula. nerve ; 19 Terminating branches of infra orbital ; 20 Orbitar branch upon the malar bone ; 21 Pterygoid branches from Meckel's ganglion ; 22 Ante- rior branches of the inferior maxillary, or third division of the fifth ; 23 Lingual or gustatory branch of the inferior maxillary, joined by the chorda tympani ; 24 Inferior dental nerve, and branches supplying the teeth ; 25 Mental branches ; 26 Superficial temporal nerve ; 27 Auricular branches ; 28 Mylo-hyoid branch. THE NERVES OF THE TEETH. 265 The posterior branch, called the pterygoid or vidian* passes from the ganglion of Meckel in the backward direc- tion, through the vidian canal at the root of the pterygoid process, then enters the cranium through the foramen lacerum medius, and divides into an inferior and superior branch. The former, called the carotid branch, enters the cavernous sinus and unites with the plexus surrounding the carotid artery, formed by the ascending branches of the superior cervical ganglion. The superior branch rep- resents rather the continued trunk of the vidian, and * Very great confusion of description and wide diversity of opinion prevail among anatomists in regard to this nerve and its connections. By some it is regarded as a sensory nerve, coming off from the fifth pair. By others it is con- sidered as a sympathetic nerve originating from Meckel's ganglion, and binding together the various superficial and deep nerves of this region. Before its entrance into the hiatus fallopii, it is found to connect itself by filaments with many nerves at the base of the skull, entering the hiatus. It is ordinarily described as uniting with the facial at its angle, where the intu- mescentia genuformis (or gangliformis) is found. The researches of Morganto, Brinton, and Malagati, show that this intumescence does not belong to the facial, but to a third division of the old seventh nerve, first described by Mis- berg, and called by him porlio intermedia, because it lies between the facial and auditory nerves. It is clearly traced into the medulla oblongata in one direction, and into this geniculate ganglion in the other. Malagati infers from his recent investigations that this portio intermedia is really a nerve of organic life, entering the brain, and associating the ear with that viscus as well as with the viscera of the thorax and abdomen — a theory which accounts for the re- markable sympathies known to exist between the ear and these various organs, how it is with this geniculate ganglion, that the superior branch of the vidian (nervus petrosus superficialis major of Arold) is connected. With it also is joined the nervous petrosus superficialis minor, which may be regarded either as a branch of the optic ganglion, or of the tympanic plexus. In any case, however, it con- nects the glosso-pharyngeal with this petrosal branch of the vidian, through the medium of Jacobson's nerve. From this same geniculate ganglion, which thus appears to be a highly im- portant sympathetic centre, the chorda tympani comes off', and, as described in the text, passes through the Glasserian fissures and unite itself with the gusta- tory branch of the fifth pair. It seems to exercise an influence upon the sense of taste ; for impairment of this function always occurs when the facial js in- jured, when its injury can involve those of the chorda tympani. The termination of the chorda tympani has been stated according to the views of the English anatomists. It cannot, however, be wholly traced into the submaxillary ganglion. Some anatomists have failed entirely to establish the connection. Guarini traces it into the lingualis muscle. At most, only a portion of the nerve can be connected with this ganglion. 266 THE NERVES OP THE TEETH. passes beneath the ganglion of Gasser and the dura mater, outwards and backwards upon the anterior cerebral sur- face of the petrous bone, to the hiatus fallopii, which it enters. In this canal it joins the portio dura, and accom- panies this latter nerve to the posterior part of the tympa- num, where it then leaves the portio dura by entering the cavity of the tympanum, and here receives the name of chorda tympani. Its entrance into the tympanum is below the pyramid, and from this point it crosses the cavity be- tween the long leg of the incus, and handle of the malleus; then it emerges along with the tendon of the laxator tym- pani muscle by the glenoid fissure, and now runs forwards and inwards, joining in its course the gustatory nerve as far as the submaxillary gland, at which point it joins the submaxillary ganglion. This ganglion is found at the posterior part of the submaxillary gland. The vidian nerve, by this lengthy and circuitous course, establishes, says Mr. Harrison, several very interesting re- lations : by it, the ganglion of Meckel, the superior cervi- cal ganglions of the sympathetic, and the submaxillary ganglion, are all connected. It also unites the superior and inferior maxillary nerves, and both to the portio dura. The third set of branches from Meckel's ganglion pass inwards, and are called the nasal or spheno-palatine. These (often only a single branch) pass through the spheno- palatine foramen and then separate into five or six branches, which supply the mucous membrane of the upper and mid- dle spongy bones. One long branch, called the nerve of Cotunnius or naso-palatine, is seen to descend along the septum-nasi as far as the foramen incisivum, at which point it meets the anterior branches of the palatine nerves, and also here a small ganglion is spoken of, but difficult to be distinguished. An orbital branch comes off next from the superior maxil- lary, this gets into the orbit through the spheno-maxillary fissure, and there divides into a temporal and a molar branch. The former is traced through the malar bone into the temporal fossa, accompanies the temporal artery, and THE NERVES OF THE TEETH. 267 is spent upon the side of the head and temple ; the malar branch also passes through the malar hone and is dis- tributed to the muscles and integuments upon this hone. The inferior maxillary nerve forms the third and largest division of the fifth. It arises from the lower portion of the Gasserian ganglion, passes through the foramen ovale of the sphenoid bone, and as it leaves this foramen unites with the motor root, and then divides into two branches, an external or superior, and internal or inferior. The inferior gives off the branch which supplies the teeth of the lower jaw. This is the inferior dental nerve. It separates from the gustatory nerve, and descends between the pterygoid muscles, along the ramus of the lower jaw to the posterior dental foramen into which it enters. It now proceeds along the canal in the inferior maxillary bone, supplying the teeth in its course to the anterior dental fo- ramen through which it emerges, and is distributed to the muscles and integuments of the lower lip and chin ; at this latter foramen a small branch is continued forward, the incisive branch, to supply the incisor teeth. The mylo-hyoideus is the only branch generally given off by the inferior dental nerve. It comes off at the posterior dental foramen and passes along a groove on the inferior maxillary bone, to the mylo-hyoid and digastric muscles. The gustatory is the next in size of the internal or lower division of the inferior maxillary. It connects with the inferior dental, and is joined by the chorda-tympani soon after this junction. It descends between the ramus of the lower jaw and the internal pterygoid muscle; proceeds ob- liquely forwards above the submaxillary gland and mylo- hyoid muscle, accompanied by the duct of Wharton, and is distributed to the lateral and anterior parts of the tongue. The gustatory gives off, in this course, filaments to the pterygoideus internus, the pharynx, tonsils, muscles of the palate and the gums, as well as communicating branches with the lingual. The auricular is the smallest branch of the inferior divis- ion, it passes posterior to the neck of the lower jaw and in 268 COMPARATIVE ANATOMY OF THE TEETH. front of the meatus externus, supplying the articulation of the jaw, the meatus auditorius, the cartilages of the ear, and then mounting over the zygoma, divides into anterior and posterior branches; which follow the course of the temporal artery. This nerve connects with the facial. The superior division of the inferior maxillary nerve has the motor trunk and divides into the masseter, the deep temporal, the buccal, and ihepterygoid branches. The masseter nerve passes in front of the neck of the lower jaw and the insertion of the temporal muscle, through the sigmoid notch, and is distributed to the masseter mus- cle. The deep temporal nerves ascend to the temporal mus- cle, in which they are lost. They are two in number, an anterior and a posterior. The buccal nerve goes between the pterygoid muscles, giving some filaments to these, and is then distributed upon the buccinator, forming a plexus upon this muscle with the infra-orbital and the facial. The pterygoid nerve consists of two or three branches, which go to the ptery- goid muscles. SECTION V. COMPARATIVE ANATOMY OF THE TEETH. The examination of similar organs in the inferior ani- mals, has always been a subject of deep interest and close study to the anatomist and physiologist, and always re- garded by them as essential to the full understanding of the structure and functions of the various organs of the human body — to the full development of medical science. What is true of the body, as a whole, applies with equal force to its several parts. Each organ finds its analogue in some one or more of the inferior animals; and the teeth, as forming parts, and indispensable parts, of the human frame, come in equally for their share of examination, in this comparison of organs, among the inferior animals. The importance of this subject has now fully aroused the master spirits of the profession to investigation in this COMPARATIVE ANATOMY OP THE TEETH. 269 department of scientific and practical research ; and their labors have already been crowned with the most useful and happy results. Cuvier and Owen, with many others, have shown that the teeth of all animals obey the same fixed and immutable law of limitation in their form, size, structure, function, and duration — in a word, that all the essential elements of their organization are obedient to, and governed by the same general laws. Still further, the teeth are now re- garded as forming the most secure basis for classifying the animal kingdom; for every class of animals having the form of its teeth differing from that of every other class, we readily recognize the distinction, and obtain a foundation of classification superior to any other — while from the great durability of these organs, and their superior resist- ance to the process of decomposition, the geologist is fur- nished with a key by which he can unlock the history of the past, and testify, not simply of the existence of ani- mals long since extinct, but accurately classify, and faith- fully describe their habits, food, and other peculiarities. To the dental student, therefore, an acquaintance with comparative dental anatomy, as far as his opportunities will allow, becomes a matter of great interest, and should always hold a high rank among the various studies per- taining to his profession. We do not, by any means, however, intend to enter into any lengthy detail on comparative dental anatomy; for such an attempt would be entirely incompatible with the limits of the present work, as well as altogether unneces- sary since the publications of Owen, Blandin, and others. All that we propose here, is simply to give such a general outline as may induce every student to examine the sub- ject for himself, and so to estimate the value of such knowledge as to be persuaded to devote all, or as much of his leisure moments as he can spare to its study and investigation. The extent of the dental organs proper seems to be lim- ited to the vertebrated division of the animal kingdom, or 270 COMPARATIVE ANATOMY OF THE TEETH. confined to those possessing a spine. In the invertebrata, instead of true teeth, the parts answering this purpose are rather horny or calcareous indurations. The class mammalia, with but few exceptions, have teeth ; and, according to M. Geoffrey, St. Hilaire, some animals which appeared to be entirely without them, were found to possess them during a portion of their life. Every tooth in the human subject consists naturally of a crown, neck and root; but this division does not apply to all the mammalia, for the incisors of the rodentia, and the tusks of the elephant, are covered with enamel over their whole extent, and are hence said to be without roots. This distinction is, however, not considered good, since por- tions of these teeth are imbedded like the roots of all others in alveolar cavities. The teeth of the mammalia are divided into " simple compound, and semi-compound or mixed/5 Like the human teeth, the simple have no " anfractuosi- ties" on their outer surface. The crown consists of a regu- lar shell of ivory, covered with a smooth and even layer of enamel. The compound teeth, on the other hand, look like several teeth joined together, as they have their surface presenting such deep sinuosities, and the cavity of the compound tooth has as many subdivisions as there are parts joined together. "A good idea," says M. Cuvier, "of the compound teeth of animals may be drawn from the human molar teeth, which have a simple crown and compound root, whilst the former have generally a simple root and compound crown. Sup- pose the roots of the large human molars, covered with enamel and joined together by cement, and you have a type of the compound teeth of other mammalia." -f*» The teeth of the mammalia are also divided, like the human teeth, into the deciduous or milk, and the permanent teeth. The number of teeth in this class varies very much, though less than in the other vertebrata. The highest number is stated to be 190, and only to be found in the dolphin. The form of the teeth constitutes the especial COMPARATIVE ANATOMY OF THE TEETH. 271 mark of distinction among the different mammalia. They are all received into proper alveolar cavities, supported by and contained within the maxillary or intermaxillary bones. The teeth of mammalia are also distinguished from those of man by their varied conformation, especially of the crown, which is asserted to differ as widely as the food upon which they each respectively subsist Those of the carniv- erous and ferocious class, which feed on flesh for example, have crowns with much stronger prominences, and more pointed and cutting edges, while those on the other hand which live on vegetable food, and are peaceable in their disposition, have flat and large crowns. The human teeth come between these two extremes, and partake of the characters of both, and hence it is that man is regarded as an omniverous animal, his teeth being adapted to living on both animal and vegetable diet. The teeth of the lower mammalia consist, as in man, of ivory and enamel, and they are arranged in similar man- ner. The animals, however, have a substance called cement, or, as Tenon terms it, the "osseous cortical substance;" which, though existing in human teeth, is by no means so abundant or extensive. The cement is harder than the ivory, but not so hard as enamel. It blackens sooner, on exposure to heat, than the latter, showing that it contains a greater amount of animal matter. It is said to be so abundant in the grinders of the elephant, as to form about half their volume. Its mode of formation is not settled : some think it is the ossification of the internal membrane of the follicle — others, with Cu- vier, that the same organ which secretes the enamel, after it is formed, then furnishes the cement. The chemical analysis of cement is given as follows : Animal matter, 43.01 Phosphate of lime, 52,94 Carbonate of lime, 4.05 The duration or period of growth in the teeth of man and mammalia varies, so much so that in the statement about 272 COMPARATIVE ANATOMY OP THE TEETH. to be made, the law of fixed limitation in the growth of all organs would seem to have some exceptions. The rodentia, pachydermata, and cetacece, are cited as instances of unlim- ited growth of the teeth, and such indefinite growth as is confined, almost in all cases, to the incisors or ca- nines. The cause of this constant growth of these teeth during life, is thus given by M. Blandin: "These teeth," he says, "are classed with those which have no roots; their internal cavity is conical in form. The pulp, conical also, rests, by a large base, upon the bottom of the alveolus, whence it receives its vessels and nerves, and not through the medium of a pedicle. "In consequence of this arrangement, it is evident that the bony matter can never surround the pulp in such a manner as to interrupt its functions ; and there is no reason," he then a'dds, "why it should not continue to secrete this substance during life." The order in which the teeth of mammalia make their appearance, is the same as in man, i. e. from before to the back part of the mouth. The number of dentitions in some of the mammalia is not limited as in man. The elephant, it is found, has its molars renewed as many as eight times. This frequent renewal of the teeth, it seems, is regulated in proportion to the life of the animal, as to whether long or short, and there are but two ways in which the animal can be kept supplied with teeth, either to replace by a new set when the present ones are lost, or by constantly adding new matter to the base of those already formed, as fast as they are destroyed by friction on their upper surface. The teeth are liable to be ivorn away from friction, some more than others, as the back teeth of the elephant are not so much worn as the front. The kind of food seems to exert a special influence in this wearing away ; those that live on grass and nuts, as the gramenivora and rodentia, have distinct lines on their cutting and grinding surfaces, and the direction of these lines indicates the direction of the teeth in the mastication of the food. In the ruminantia the lines are transverse, showing that the friction is from side COMPARATIVE ANATOMY OF THE TEETH. 2*73 to side, while in the rodentia they are antero-posterior, showing the friction to be from front to back. In the carnivora, on the other hand, or those that live on flesh, there is very little wearing away of the teeth, scarcely any lines from friction to be seen, and the points and cut- ting edges are preserved to the end of life. This ine- quality in the wearing of the teeth has been turned to practical account in determining the age of the horse, and the incisors are those by which the age is known. " The middle teeth, says M. Cuvier, begin to appear about fifteen days after birth, and at two years and a half the middle ones are replaced ; at three and a half the two next follow, and at four and a half the outermost or corner teeth. All these teeth with originally indented crowns, lose by degrees this character by detrition. At seven and a half or eight years the depressions are completely effaced, and the horse is no longer marked. The inferior canines appear at three years and a half, the superior at four years. They remain pointed until the sixth, and at ten begin to peel away." The horse seldom lives longer than thirty years. With these general remarks, we will now proceed to run a very brief contrast between the teeth of the different or- ders of the class mammalia and those of man, commencing / o with the highest in the scale and then descending. The first order is the QUADRUMANA. — This order is divided into the monkeys, simicB) and lemurs. The chimpanzee and ourang-outang con- stitute the highest order of monkey, and are next to man in their organization. According to Mr, Owen, the most prominent points of distinction between the dentition of man and that of these higher quadrumana, consist in the " absence of the interval between the upper lateral incisor and the canine in man, and the comparatively small size of the latter tooth," (Fig, 75.) The human teeth are more equal in size, and describe a more regular curve in both jaws, and do not, as just stated, present the vacant space of the monkey. The in- cisors of the human teeth are smaller in proportion to the 18 274 COMPARATIVE ANATOMY OF THE TEETH. FIG. 75. A molars than those of the chimpanzee or orang. The upper and lower bicuspids are also smaller in proportion to the molars, than those of these animals. In the human teeth the crowns of the true molars are observed to be larger in proportion to the bicuspids, still larger in proportion to the canines and incisors, and larger in proportion to the jaws, and have the borders of their grinding surface more round than is found in the chimpanzee and orang. When the per- manent teeth appear, it is remarked that the first true molar in both upper and lower jaw is " much more worn," in comparison with the other molars, than in the chimpan- zee and orang, in consequence of the longer time which elapses between the appearance of the first and last true molars of the human teeth and those of these animals, and consequently the greater amount of friction the first molars are subject to. The number of teeth in these quadrumana is the same as in man. The deciduous set are the same in number. The following contrast between the human deciduous teeth and those of the chimpanzee and orang, is from the pen of Mr. Owen. "The upper milk incisors of the chimpanzee," he says, "are relatively larger than in man, especially the middle pair, but the disproportionate size of these is still more man- FIG. 75, A represents the superior dental arch of man. FIG. 75, B represents the superior dental arch of a chimpanzee. COMPARATIVE ANATOMY OF THE TEETH. 275 ifest and characteristic of the orang, and the outer angle of the lateral incisors is more rounded off in this quadruman. The crown of the canine is longer and more pointed in the chimpanzee than in man; still more so, and farther apart from the incisor, in the orang. The first molar is as large in the human subject as in the chimpanzee, and its crown is divided into two principal cusps, hut the outer and larger one has a small subdivision notched off posteriorly, and the inner cusp is relatively larger than in the chimpanzee. The first upper molar of the orang is simply bicuspid, but is larger than in the chimpanzee. The second molar of the human child could scarcely be distinguished from that of the young chimpanzee, both are quadricuspid, and the same oblique ridge crosses the grinding surface from the ante- ro-internal, to the postero-external tubercle, but the pointed summits of the two outer cusps are a little more extended in the chimpanzee. The second molar of the orang, besides its larger size, has the four tubercles better defined, and the oblique ridge less developed. " The lower deciduous incisors of the anthropoid apes differ from those of the human subject in their superior size, greater relative thickness, and the lateral incisor more particularly, by the rounding off of the auter angle. "The lower canine of the chimpanzee has a larger, longer, and more pointed crown, with a sharp posterior edge; this is less marked in the canine of the orang, which is larger arid thicker than in the chimpanzee; the crowns of the upper and lower canines are more obliquely opposed, the lower one being more advanced in those apes than in the human subject. " The first lower deciduous molar of the human subject has four tubercles and a small anterior ridge, and is larger than that of the chimpanzee, which supports a single large pointed cusp and a posterior ridge. The first molar of the orang has a similar simple crown, but is as large as that of the child. The second molar is of equal or superior size in the human subject to that in the chimpanzee, but it supports three outer and two inner cusps, while in the 276 COMPARATIVE ANATOMY OF THE TEETH. chimpanzee it has but four cusps; in the orang, the fifth external and posterior tubercle is feebly indicated. The deciduous molars of the human subject, as in the chim- panzee and orang, have each three fangs in the upper and two in the lower jaw." In the order of succession in the teeth of these quadru- mana and man, there is some difference. It has already been stated, in the description of human dentition, that the first true molar and first incisor are the earliest to appear in the permanent set; and between these two points, Mr. Hunter remarks, the teeth progress more rap- idly than those behind. But in the quadrumana this is not the case, and the progress is slower ; for in these the second molar is found to precede the bicuspid, and the last molar the canine. And the cause of this difference is assigned to the difference in the food. Monkeys, living on fruits and meats, require the use of their grinders at an earlier period than either the canine or incisors. In the baboons and mandrills , which are a step lower than the monkey tribe, we find their denti- tion most especially distinguished from the human, by the canine teeth presenting the ferocity and strength of the carnivorous animals. Those of the mandrill are described as " weapons most formidable for their size and shape," the upper canines especially, which pass behind the crowns of the lower incisors, and on the outside of the first lower bicuspid, which seems pressed back, as it were, by the ac- tion of the upper canines. A considerable space divides the upper canine from the incisors — a shorter one separates it from the bicuspid. The first bicuspid of the lower jaw is distinguished by the base of its crown having an unusual anterior prolongation, which is reduced to a cutting edge by the friction of the upper canine. The class of lemurs are the lowest in the scale of the quadrumana, and differ from these in their dentition, as well as from the human race, by having thirty-six teeth instead of thirty-two ; the difference being in the bicuspids, of which these animals have six to each jaw,, three on COMPARATIVE ANATOMY OF THE TEETH. 27 T either side instead of four, as in man and the higher monkey. The two incisors of the upper jaw are separated by a wide space from the two on the left, and are small, vertical, and have their crowns short and expanded. The canine is long, compressed, and curved, with its edge sharp and pointed. The three bicuspids present, on the inner side of their crowns, a tubercle, while on their outer there is extended a compressed and pointed lobe. Both jaws have their first true molars the largest. The first bicuspid, in the upper jaw, has its two roots connate or joined together; those of the other two are distinct. The roots of the upper molars, as in the human teeth, are three in number ; but in the lower jaw, both bicuspids and molars have only two roots. The number of deciduous teeth in the lemurs is twenty-four, instead of twenty, as in man — the excess being in the molars. Among the quad- rumana there are two genera described, which are most remarkable for their very singular and anomalous denti- tion. They consist of the goleopitliecus (the weasel-like monkey) and the cheiromys. The former are said to resemble the bat, in having a kind of wing, formed of a fold of the integument,, reaching from the front to the hind extremity, and may be called flying monkeys. The teeth in this genus are thirty-four in number, i. e. four incisors in the upper jaw, two on either side, and six in the lower jaw, three on either side, making ten incisors in all — two more than in man. The two anterior upper incisors have a wide space between them, are very small, and have their crowns expanded and presenting three or four tubercles. The second incisor of the upper jaw, which is said to be connected with the intermaxillary bone, has one very striking peculiarity in having two roots. Its crown is of a triangular shape, having, at the front and posterior base, a small talon — also dentations, two anterior and three posterior, at the same points. The upper canine has, very unlike the human, two roots. 2*78 COMPARATIVE ANATOMY OF THE TEETH. The first upper biscupid has its crown of a trihedral shape. The second bicuspid has a pointed talon at its base. The crowns of the first two incisors of the lower jaw pre- sent a very peculiar arrangement in the form of a comb. This tooth-like or pectinated appearance, is compared to the little notches on the edge of aa new-formed hunian incisor," though the serrations are much deeper and more numer- ous. These teeth have a single root. The third incisor is thought to resemble a canine, though its crown is described as being broad, horizontal, and having four shallow notches on its margin ; this tooth, also, has a single root. The lower canine, like the upper, has two roots. The milk teeth are twenty-two in number — ten to the upper jaw, and twelve to the lower. In the cheiromys a resemblance is traced to the rodentia, in the chisel-like incisors of both jaws, which make but a single pair, and are large and curved. The canines are wanting, and a wide space separates the incisors from the molars. As the cutting edge of the teeth below does not strike against the "posterior ridge" of those above, M. Blainville supposes that the chisel teeth of the incisors have a differ- ent use from those of the rodents, and that the cheiromys employ them as "cutting pincers to remove the bark of trees, in search of larvae or insects," though the flat, smooth crowns of the molars would seem to show their food not to be entirely of this character. The upper jaw has four mo- lars on each side, and the lower three, placed vertically and parallel. The first upper molar is the smallest, and the second the largest of that jaw. In the lower jaw the last molar is the smallest. A striking contrast with the human molar exists in the roots. In the cheiromys the first and last molars of the upper jaw have but one root ; the two middle have each three roots. In the lower jaw the first molar has two roots, the other two but one. INSECTIVORA. — This order is regarded as the transition step between the quadrumana and carnivora. The differ- ent genera are remarkable for the varieties in their teeth, COMPAKATIVE ANATOMY OF THE TEETH. 2*79 in number, shape, and size. The most common character- istic found to prevail is the presence of "several sharp points upon the crowns of the true molar teeth." This order is divided into the families of moles (talpidee), shrews (solicidge), and hedge-hogs (erinacidas.) The mole of the cape, as it is called, according to Mr. Owen, has forty teeth. Its dental formula is to the up- per jaw on either side, three incisors, one bicuspid, and six molars ; to the lower jaw, three incisors, two bicuspids, and five molars. The American mole has thirty-six teeth: to the upper jaw, on either side, three incisors, one canine, three bicuspids, three molars; to the lower jaw_, two inci- sors, no canine, three bicuspids, three molars. The common mole has forty-four teeth, in the arrangement of which there is some difference among naturalists. M. Cuvier rates no canine to the lower jaw, and gives four bicuspids and three molars on either side to both jaws. Mr. Bell allows two canine to the lower jaw, gives no bicuspids, and makes seven molars to the upper, and six to the lower jaw, on either side; while M. Blainville has, to both upper and lower jaw, on each side, four incisors, one canine, three bicuspids, three molars. In the hedge-hog, one variety has thirty-six teeth. The formula given is, incisors two, canine one, bicuspids three, molars three, to both upper and lower jaw, on either side. The common hedge-hog has the same number, but differ- ently arranged as follows: incisors three, bicuspids four, molars three, on either side, in each jaw. Another variety has forty-eight, i. e. incisors three, canine one, bicuspids four, molars four, on either side, in each jaw. CHEIROPTERA. — This order includes two divisions of the bats — first, those that live on insects, and second, those that live on fruits. The number of teeth belonging to the first is thirty- eight, i. e. incisors two, canine one, bicuspids three, molars three, to the upper jaw, on either side ; and to the lower, incisors three, canine one, bicuspids three, molars three. The vampire or blood-sucking bat has but twenty teeth. 280 COMPARATIVE ANATOMY -OF THE TEETH. The dental formula is, incisors one, canine one, bicuspids two, to the upper jaw, on either side ; and to the lower, incisors two,, canine one, bicuspids three. The bats which live on fruit have thirty-four teeth. Their dental formula is, to the upper jaw, on either side, incisors two, canine one, bicuspids two, molars three; in the lower, incisors two, canine one, bicuspids three, molars three. CARNTVORA. — Animals of this order live entirely on one kind of food, i. e. flesh; and their dental system being de- signed not only to masticate, but also to obtain, seize, and kill their prej, their teeth are much more extensive than in man. The different genera present variations from the regular type as established in the feline or cat tribe. FIG. 76. Among the whole order there are found to be six in- cisors in each jaw, with few exceptions. The canines are never absent, are largely developed, and have long, eoni- FIG. 76 represents the deciduous and permanent teeth of the dog. 2 3 4 d Deciduous molars of the upper and lower jaw. 2 3 4 p Permanent molars. d c Deciduous canine of both jaws, d i Deciduous incisors of both jaws, i Permanent incisors. 2 m 3 m Tubercular molars. COMPARATIVE ANATOMY OF THE TEETH. 281 cal, sharp-pointed and cutting crowns. The variations from the type are found in the molars. We will give a few examples in illustration. The cat, taken as the type of the order, has 28 teeth — the upper jaw having, on either side, incisors 3, canine 1, hicuspids 3, molar 1. In the lower jaw there are, incisors 3, canine 1, hicuspids 2, molar 1. In the upper jaw the first bicuspid has a single root, with one exception. The second bicuspid has two strong diverging roots; the third has three. In the lower jaw the first bicuspid has two roots. The number of milk teeth in the cat is 26. The upper jaw has, incisors 3, canine 1, molars 3, on either side. In the lower jaw there are, in- cisors 3, canine 1, molars 2. The dog has 42 teeth. (Fig. 76.) In the upper jaw there are on either side, incisors 3, canine 1, bicuspids 4, mo- lars 2. In the lower jaw there is an additional molar. There is a FIG. 77. single root to the incisors, canines, and first.bicuspids of both jaws, all the rest in the lower jaw have two, except the sec- ond bicuspid, which is con- nate. The sec- ond upper bi- cuspid, which is also called sectorial, has three roots, the first true molar has four, the last three roots. FIG. 77 represents the deciduous and permanent teeth of the bear. 1 2 3 4 1) Deciduous molars of the upper and lower jaw. p Permanent molars, d i Deciduous incisors, c Canine teeth. 282 COMPARATIVE ANATOMY OF THE TEETH. The hyena has 34 teeth. In the upper jaw on either side there are, incisors 3, canine 1, bicuspids 4, molar 1. In the lower jaw there is one bicuspid less. The number of deciduous teeth is 28, i. e. incisors 3, canine 1, molars 3, to each jaw on either side. The weasel has 34, the otter 36, the badger 30, the raccoon 40, the bear 42. (Fig. 77.) The deciduous teeth of the bear are 22, and the seal has 34 teeth. MARSUPIALIA. — This order, so called from having a pouch for the accommodation of their young, are divided into the carnivorous and herbivorous genera. The opossum and kangaroo are familiar examples under this head. The dog-headed opossum (thylacinus) has forty- six teeth. In the upper jaw, on either side, there are — incisors four, canine one, bicuspids three, molars four; in the lower jaw are found — incisors three, canine one, bicus- pids three, molars four. In other varieties of the opossum the teeth vary in number, being 42, 48, 50 and 54. The kangaroo has twenty-eight teeth. The canines are absent. The animals of this genus live on herbs. The dental formula is, to the upper jaw, on either side, incisors three, bicuspids one, molars four ; in the lower jaw, there are, molars four, incisor one, bicuspid one. Other varieties have only twenty-four teeth. KODENTIA. — This order includes the squirrel, rabbit, rat, beaver, &c. The incisors form the distinguishing characteristic of this order. There is one on either side, separated from the short series of molars by a wide space. The upper ones describe a large segment of a small circle, and are regularly curved ; the lower ones are a smaller segment of a larger circle. These teeth are called " scalpriform" or chisel-like. The molar teeth are described as presenting numerous varieties, representing, in fact, all the modifications found in the om- nivorous and herbivorous genera of mammalia. In some of the rodents, as the Chili rats, the molar teeth have no roots. In others, as the beaver, they have short roots. COMPARATIVE ANATOMY OF THE TEETH. 283 The mode in which the teeth are implanted in the jaws varies according to the diet. Those, for example, like the true rat, which live on a mixed food, do not require so great a depth of the crown, and the teeth are hence not so firmly fixed, nor so large as in those rodents whose food is entirely vegetable, and where the friction is greater. The highest numher of teeth in this order is stated at twenty-eight. The rahbit has six molars on each side, in the upper jaw, and five in the lower. The squirrel has five molars in the upper on either side, and four in the lower. The rat has three molars on each side, in both jaws, though the spring-rat, as it is called, has four molars in both jaws, on each side. EDENTATA. — It would be supposed from the name of this order that all the genera composing it were without teeth. Hence Mr. Owen very justly remarks, it is to be regretted that such a term should have been applied, seeing that all the species of this order, except two, have teeth, though nearly all are without incisors. The ant-eater, armadillo, and sloth, are examples under this head. The ant-eater has twenty-six teeth — seven on each side of the upper jaw, and six on each side of the lower. The number in the armadillo is stated to vary from twenty-four to twenty-six on each side of the upper jaw, and twenty- two to twenty-four in the lower ; making, in the whole, from ninety-four to one hundred teeth. The sloth has eighteen teeth, all molars — there being five on each side of the upper jaw, and four on each side of the lower. The extinct gigantic animals by the name of megather- oids, some of whose teeth are nearly a foot in length, belong also to this order. PACHYDERMATA. — This order includes the elephant, mas- todon, hippopotamus, rhinoceros, hog, horse, &c. The elephant, distinguished by its two enormous tusks, has 28 teeth. In the upper jaw, on each side, there are two incisors and six molars. In the lower there are only six molars on either side. The tusks are situated in the inter- 284 COMPARATIVE ANATOMY OF THE TEETH. maxillary bones, and are preceded by deciduous ones. These latter appear between the 5th and 2*7 th month; are about two inches in length, one third of an inch in diame- ter, and are shed between the first and second year. In about a month or two after this period, the permanent tusks are described as cutting the gum, and are then about an inch in length. At birth the alveolus of the permanent tusk is a round cell placed at the posterior and inner part of the temporary alveolus. The tusks are called the incisor teeth of the ele- phant, and are considered, in proportion to the body, the largest of all the teeth. They are stated to have measured nine feet in length, having a base of eight inches, and weighing 150 pounds. This is an unusual weight, the more common being from fifty to seventy pounds. In some varieties the tusks are straight, and point downwards, and in others of a still more anomalous kind, one tusk has been seen horizontal, and the other vertical. The molar teeth are of immense size and complex structure. The crown is mostly hid in the socket, only a small portion appearing above the gum. It is divided into several per- pendicular transverse plates — coated with enamel, and then covered with cement — which unites the several divisions of the crown; these divisions come together at the base and form the body of the crown from whence the roots proceed. In the development of the grinders, the summits of the anterior plates begin to be formed first, and then the others in succession, the anterior being in use before the posterior are formed. The first molar is stated to have four of these vertical plates or divisions of the crown,, and two roots. The second molar has eight or nine plates, and also two roots. The third molar has from eleven to thirteen plates, and has a small anterior and large posterior root. It is thought these three may probably be deciduous teeth. The fourth molar has from fifteen to sixteen plates in the crown and three roots. The fifth molar has from seventeen to twenty plates, appears above the gum about the twentieth COMPARATIVE ANATOMY OF THE TEETH. 285 year, and is found not to be shed before the sixtieth. The sixth and last molar has from twenty-two to twenty-seven plates. Its antero-posterior length in the line of the curv- ature is found to measure from twelve to fifteen inches, and breadth about three and a half inches. The mastodon is an extinct race. It has the tusks of the elephant, and differs in its grinders, having their surfaces divided into " wedge-shaped transverse ridges," instead of the numerous vertical plates of the elephant. The dental formula is given as twenty-eight ; seven teeth on each side to the upper jaw, and the same number to the lower. This number, however, combines both the decidu- ous and permanent set. The hippopotamus. This monster of the waters is exceed- ingly interesting to the dentist, as from its teeth, informer times, were mostly supplied the best artificial substitutes for the human. It was most appropriate for this purpose, as the dentine was extremely hard, and sections of it sus- ceptible of very high polish. The number of teeth, as given by M. Cuvier, is thirty-two, i. e. six molars on each side of each jaw, two incisors on each side of each jaw, and two canines also on each side of each jaw. The three ante- rior molars (the premolars of Mr. Owen) are conical; the posterior present two pairs of points. The upper incisors are short, conical and recurved, the inferior "prolonged, cylindrical, pointed, and horizontally projecting." The upper canine is straight, the lower very large and bent back, recurved. Rhinoceros. This genus has no canine teeth. Its in- cisors vary, though the usual number given is eight, two on each side of both upper and lower jaw. The number of molars is twenty-eight. This animal is remarkable for its single horn, though in some varieties there are two. The African rhinoceros is said to have two horns, and no incisors. The hog, (suidce.) This family, among the ungulata, comprises the greatest varieties in dentition. The ca- nines form the most prominent feature of this group, 286 COMPARATIVE ANATOMY OF THE TEETH. being remarkable for their " extraordinary size, shape, and direction." This is best illustrated in the wild boar, where FIG. 78. A they curve forwards, outwards and upwards. The molars are regarded as complex in structure as those of the ele- phant, while the incisors vary in number in the several genera. The usual number of teeth is set down at forty- four. To both jaws on either side there are, incisors 3, FIG. 78, A represents the Permanent Teeth of the Hog. lnt,2m, 3m, 1st, 2d and 3d Molars. lp, 2p, 3/>, 4p, 1st, 2d, 3d and 4th Premolars. li, 2i, 3i, 1st, 2d and 3d, Incisors, c Canine teeth. FIG. 78, B represents the Deciduous and Permanent Teeth of the Hog. The figures and letters point so distinctly to the different kinds of teeth, as to require no further explanation. COMPARATIVE ANATOMY OF THE TEETH. 287 canine 1, bicuspids 4, molars 3, The number of milk teetli is made twenty-eight. Incisors 3, canine 1, molars 3, to both jaws on either side, In the Peccari the dental formula numbers thirty-eight teeth — i. e. in the upper jaw, on each side, there are, inci- sors two, canine one, bicuspids three, molars three; in the lower, on each side, are, incisors three, canine one, bicus- pids three, molars three. The Horse, (equidce) This noble and useful animal, be- longing to the family solidungula, or singlQ-hoofed variety, has forty teeth. In both jaws, on each pIGi 79> side, there are three incisors, one canine, three bicuspids, and three molars. The lower canines, according to M. Cu~ vier, are only sometimes present in the male, and always wanting in the female. Between the canines and first bicuspids there is a wide space corresponding to the angle of the mouth, where the bit is re- ceived. The incisors are slightly curved, having long, subtrahedral fangs, taper- ing to their extremity, and closely ar- ranged in the segment of a circle. These teeth, says Mr. Owen, are distinguished from those of all other animals "by the fold of enamel which penetrates the body of the crown from its broad, flat summit, like the inverted finger of a glove." This fold encloses a cavity, which pre- sents the form of an island, when the tooth begins to be worn. This cavity is partly filled by "cement, and partly by the discolored substances of the food, and is called the mark." It is described as being usually obliterated, in the middle incisors, about the sixth year — in the second inci- sors, about the seventh; and the third, about the eighth, FIQ. 79, A longitudinal section of the Incisor of a Horse, e Enamel. d Dentine, c Cement. c Cement reflected into the depression of the crown, s Colored tartar and food filling up this cavity and constituting what is known as the " mark" and made use of to tell the age of the horse. 288 COMPARATIVE ANATOMY OF THE TEETH. in the lower jaw. It is longer disappearing in those of the upper jaw. EUMINANTIA. — This order is considered to be the best determined in the whole class of mammalia. The camel, lama, dromedary, ox, sheep, goat, stag, &c., are varieties of this order. The genera are divided into those which are without horns, and those which have them. The latter class is by far the most numerous. The camel and lama are examples of the former, while the ox, ram, stag, &c., are specimens' of the latter. Another division is into those in which the horns are solid, and those in which they are hollow. In the development of the horns arid teeth, the relation seems to be inverse, for where the horns are present, we find the canines absent, and where the horns are wanting, as in the musk, canines are not only seen, but also a pair of incisors in the upper jaw. The diiferent genera are called ruminantia, from the pe- culiar faculty they possess of masticating their food a second time, by returning it to the mouth after first swal- lowing it. This singular faculty depends on the structure of the stomach, or rather stomachs, which are four in number ; and the first three are so related to each other that the food may enter either of them, as the ossophagus ends at their common point of communication. The first stomach is called the paunch, and receives the vegetable matters from the first mastication. This passes into the second, which is of honey-comb formation, and here the food is moistened and compressed into little pellets called cud, which is now returned into the mouth to un- dergo a second mastication. It is now passed from the mouth into the third stomach, which is laminated in its appearance, and from this it enters into the fourth, which has the rugce, and which is the seat of digestion proper. One characteristic in the teeth of this order is, the ab- sence of incisors and canines in the upper jaw. This is furnished by a callous pad as a substitute. A second char- COMPARATIVE ANATOMY OP THE TEETH. 289 acter is the constancy of eight incisors in the lower jaw, the two outer of which Mr. Owen calls canine. The usual dental formula gives 32 teeth to the ruminantia: 6 bi- cuspids and 6 molars to the upper jaw; to the lower, 6 incisors, 2 canines, 6 bicuspids, and 6 molars. A wide space separates the incisors and bicuspids. The upper bicuspids have three roots; the upper true molars have four roots. In the lower jaw both bicuspids and molars have but two roots; but the second root in the last molar consists of two connate roots. CETACEA. — This order of mammalia includes the whales, which have no teeth,* properly speaking, but horny sub- stitutes, called "whale-bone" or "baleen." The so-called teeth of the right whale are in the form of plates, termin- ating in a fringe of bristles. In a new-born whale Mr. Owen found the number of these plates to be 190. The largest are arranged on each side of the upper jaw in a longitudinal series and close to each other, vertically, with their flat surfaces looking forwards and backwards, and their free margins outwards and inwards. The smaller plates are disposed in an oblique series within the larger. The base of each plate is described as being fixed upon a pulp developed within a broad, shallow depression of the gunr, and covering the entire surface of the maxillary and anterior portion of the palate bones — the whale thus hav- ing palatal teeth. The base of each plate is hollow, for receiving the pulp — bearing the same relation to it that the pulp of a true tooth does to its cavity. THE SECOND CLASS OF ANIMALS, BIRDS (AVES.) As the organs of prehension of this class consist of a horny substance, and are therefore not teeth properly speaking, a remark or two is all that is considered necessary to be made in reference to these substitutes or mere representatives of teeth. It is true, as has been remarked, that strictly speaking, * Some varieties in this order, it is thought, have teeth proper. 19 290 COMPARATIVE ANATOMY OF THE TEETH. the beak of the bird is an organ of prehension and mastica- tion, and often a powerful weapon for either offence or de- fence, though in its form and structure it is more like the claws and nails than teeth. The beak in birds of prey is hard, in water birds it is comparatively soft. The form is very various, and corre- sponds with the kind of food and the habits of the several varieties. In some birds of prey it is curved into a "hook with sharp cutting edges." In others, as in the stork, it is straight; some have it bent downwards, others upwards; some have it compressed, as the penguin, transversely; and others, as the duck, have it flat. The jaws present, in some, distinct elevations or notches, resembling teeth. The duck has these indentations regu- larly arranged, and supplied with branches of the inferior maxillary nerve. THIKD CLASS OF ANIMALS — REPTILES (REPTILIA.) The teeth of this class, occupying a position intermediate between those of the bird and of the .fish, are thought to partake thereby of the characteristics of both. The tortoise has the beak of the bird, and with this exception all other reptiles are said to have true teeth. These are pointed and conical, and resemble more those of the carnivorous class, and form weapons of attack and defence. The number of teeth belonging to reptiles is not deter- mined, but it is greater than in man. They are fixed in the jaws, though sometimes as in the serpent, are placed in the palate. They are without roots, and are fixed in alveoli which are more narrow at their external opening than at the bottom. The teeth of this class are developed at a very early age, and always the number is the same. Those which have just come forth from the egg have as many as the adult animal, ten or twenty feet in length. Eeptiles shed their teeth, it seems, with greater fre- quency and facility than most other animals, These or- COMPARATIVE ANATOMY OF THE TEETH. 291 B gans grow with age, and are found of a size proportionate to the dimensions of the animal. Serpents have teeth FlG> 80> B both upon the palate and jaws. The ven- omous teeth are at- tached to the upper maxillary bone, and are curved backward in a semi-circular form. The roots are situated in the ante- rior part of the jaw, and 'are not mova- ble, according to Mr. Blandin,butare fixed firmly to the bone; the jaw itself, which is movable, causing the apparent motion. These poisonous teeth are much longer than any other — and have a canal running the whole length of the teeth, which contains the excretory duct of the gland furnishing the poison. This ca- nal terminates on the free extremity of the tooth by an opening, through which the animal ejects the poison. The sac sur- rounding the base of the fang has within it several rudi- Fio. 80, A, B, C represent the poison Fangs of Serpents. B Longitudinal section of the fang, v poison duct; accented v its outlet. FIG. 80, D represents also a section of the poison fang magnified — f p showing pulp canal, calcigerous tubes, and dentine enclosing the poison canal. 292 COMPARATIVE ANATOMY OF THE TEETH. mentary fangs. As many as eleven have been seen, so that when one is shed there is another to take its place. All the frogs are said to have teeth in both jaws, and all, with the exception of a single variety called the pipa, have teeth in the roof of the palate. FOURTH CLASS — FISHES, (PISCES.) Fish constitute the last class of the vertehrated division of the animal kingdom. Their dental system presents great variety, both in number and arrangement. The teeth are found in all parts of the mouth and pharynx, and are distin- guished, according to their situation, into intermaxillary, mandibular, palatine, vomerial, lingual, bronchial, and pha- ryngeal. The teeth of fish are either received into alveolar cavi- ties, and are firm and immovable, or are removed from the maxillary bones, and have not the cavities, as in the cartila- ginous fishes, except the saw fish, and are movable as in the shark, which has the power of elevating and depressing its teeth. The fact of the teeth being thus removed from the bone and connected with mucous mem- brane, is regarded as conclu- sive in reference to the theory of their origin from mucous membrane. The form of the teeth of fish is exceedingly various — some are conical, others flattened; the conical form the largest number, and sometimes present a single point, at others two or three points. In a variety called the scarius there are five or six rows, composed each of five or six teeth united by a species of cement. FIG. 81 represents the teeth of the Rock Fish, (labrus.) They are attached to the inferior pharyngeal bone, are very numerous, are scattered over a broad surface, and are said to resemble a «* pavement." COMPARATIVE ANATOMY OF THE TEETH. 293 The osseous teeth, fixed in alveoli, are, after their full development, described as being "closely soldered to the circumference of the cavity in which they are placed." Those fish whose teeth are sharp, with a strong incli- nation backwards as in the pike, or tooth-like and cutting as in the shark, are regarded as the most carnivorous and voracious. Those on the other hand whose teeth are flat- tened, or only pharyngeal, are viewed as the least carnivor- ous and most peaceable in their dispositions. SECOND DIVISION OP THE ANIMAL KINGDOM. THE INVERTEBRATA OR ANIMALS DESTITUTE OF A SPINE. — The teeth of this division have an analogy of function with those of the vertebrata, being situated, many of them, at or near the mouth of the alimentary tube, and laying hold of, retaining, and dividing the food — thus performing the functions of prehension and mastication, though in structure they are considered by some as farther removed from true teeth than the hair. The teeth of the invertebrated division are mostly found in the stomach — a very singular and striking fact; and Mr. Blandin remarks, " The higher the animal is elevated in the scale, the higher are the dental organs elevated in the alimentary canal. "In the Crustacea andmollusca they are placed principally in the stomach. In fishes they reach the pharynx. In rep- tiles the posterior part of the mouth— whilst in the mam- malia they are confined to the anterior and lateral parts of the mouth." In the Crustacea the dental organs found in the stomach consist of calcareous matter placed on a kind of skeleton. This so-called skeleton of the stomach is composed of transverse and lateral ribs, to which these teeth are at- tached. Upon the lateral ridges the two larger teeth are placed and have flat crowns, with depressions. The crown in the crab is striated, and has on its inferior border large " denticulations." The great lobster is described as having nine of the rib- 294 ACTIVE OKGANS OF MASTICATION. like elevations. At tlie point of junction of the lateral and transverse ridges, another ridge is spoken of as branching off, which has a tooth, and also three and sometimes five sharp, hooked, and small pointed elevations. The hooked teeth are represented as seizing the food and carrying it between the teeth with flattened crowns. Insects and worms cannot be said to have any organs which can be compared to teeth. The stomachs of some of them seem to be furnished with " scales or horny hooks," which are supposed to be intended for a kind of mastication. SECTION VI. ACTIVE ORGANS OF MASTICATION, CONSISTING OF MUSCLES. 1. Masseter Muscle. — The same dissection made for the muscles of prehension will exhibit this muscle. FIG. 82. The masseter (fuuHtuofUM, I chew) is a superficial, thick, and strong muscle, situated at the side and back part of the face, and extended between the zygoma and angle of the lower jaw. It consists of two portions, an anterior and posterior, or superficial and deep, which de- cussate. The anterior is the larger, and arises tendinous from the inferior edge of the malar bone, and from the point where it unites with the maxillary. The posterior arises fleshy from the zygomatic arch as far back as the glenoid cavity. The fibres of the anterior portion pass backwards and down- wards; of those of the posterior, some descend obliquely FIG. 82 Lateral view of the Muscles of the face, cranium, and external ear. 1 Occipito-frontalis, 2 Orbicularis palpebrarum, 3 Pyramidalis nasi, 4 Compressor nasi, 5 6 Levator labii superioris alseque nasi, 7 Zygomaticus mi- nor, 8 Zygomaticus major, 9 Masseter muscle, 10 Buccinator, 11 Depressor anguli, or triangularis orisj 12 Depressor labii inferioris, 13 Orbicularis oris, 14 Anterior auris, 15 Superior auris, 16 Posterior auris, 17 External lateral ligament, 18 Deep-seated portion of masseter, 19 Fascia temporalis. ACTIVE ORGANS OF MASTICATION. 295 forwards, others vertically, and both portions are inserted, tendinous and fleshy, into the external surface of the angle and ramus of the lower jaw as high as the coronoid process. Function. If the anterior portions of both muscles act together, the jaw is carried forwards — if the posterior act, it is carried backwards ; if both anterior and posterior, on opposite sides, act together, the lower jaw will be power- fully raised to the upper. If the superficial portion, on the one side, act alone, it can throw the chin to the oppo- site side. If the deep portion act by itself, it can rotate the jaw to its own side. This muscle is one of the chief agents in mastication, as it has the power of directly bringing the lower jaw to the upper, and thereby dividing the food, and also of rotating it, whereby its trituration is effected. The masseter is covered by the skin, a few fibres of the platysma, orbicularis palpebrarum, and zygomatic muscles, as well as by a part of the parotid gland and duct, and the transverse facial vessels and nerves. 2. Temporalis Muscle — (tempora, the temples.) Dissection. — Make an incision along the semicircular ridge upon the side of the cranium, extending from the external angular process of the FIG. 83. frontal bone, along the parie- tal, back to themastoid process of the temporal bone. Turn this portion of skin down to the zygoma, and the temporal aponeurosis is brought to view. This is a white, strong, and shining fascia, which is at- tached above to the semicir- cular ridge, and below to the zygoma. It covers the temporal muscle — is thin above where the muscle is seen through it, and thick below where Fio. 83 Temporal Muscle, the fascia being removed. 1 Temporal muscle, 2 External lateral ligament, 3 Insertion of temporal muscle. 296 ACTIVE ORGANS OF MASTICATION. it consists of two layers separated by some fat, vessels, and nerves. Turn this fascia down to the zygoma, and the up- per and larger portion of the temporal muscle is exposed. Now saw through the zygomatic arch at either end, and turn it down with the masseter, and we have brought to view the lower portion of the temporal. Thus exposed, the temporal muscle is seen to arise on the side of the cranium from the whole length of the semicircular ridge, and from the surface below this ridge, formed by the frontal, parie- tal, squamous portion of the temporal, and greater wing of the sphenoid bone, as low down as its crest ; and from the under surface of the fascia temporalis. From this ex- tensive origin, the fibres converge to a strong tendon, which is inserted into the coronoid process, nearly sur- rounding it, and continues forwards as far as the last molares. Function. — To bring the lower jaw to the upper, in the cutting of the food in mastication. The posterior fibres, by drawing the lower jaw backwards, are a great security against dislocations of this bone. 3. Pterygoideus externus. Dissection. — Turn off the masseter muscle close to the bone, and take out a section of the ramus by sawing be- FlG- 84- tween its angle,, and the root of the condyle, and the pterygoid muscles will be exposed. The pterygoideus externus is a short triangular muscle, running horizontally and situated deep be- hind the ramus of the lower jaw. It arises by two heads — the one from the crest on the great wing of the sphenoid bone, at its root, the other from the outer surface of the external pterygoid plate, and tuberosity of the upper maxilla — the two portions converge and pass FIG. 84 represents the Pterygoid Muscles; the zygomatic arch and ramus of the lower jaw being removed, a 6 Pterygoideus externus. c Pterygoideus interims. ACTION OP THE MUSCLES OF MASTICATION. 297 backwards and outwards, to be inserted into the internal and anterior part of the neck of the lower jaw and the in- terarticular cartilage. Function. — When one muscle acts, it turns the jaw to the opposite side; when both act alternately, they give the ro- tatory or grinding motion. If they act together, the jaw is thrown forward. 4. Pterygoideus internus, (Fig. 84.) This muscle is thick and short, and situated behind the ramus and angle of the inferior maxilla. It is inferior to the external pterygoid, and parallel to the superficial layer of the masseter. It arises fleshy and tendinous from the inner surface of the external pterygoid plate, and pterygoid process of the palate bone, occupies the greater portion of the pterygoid fossa, and passes downwards and outwards to be inserted tendinous and fleshy on the inner surface of the angle of the jaw. Function. — It is a rotator of the jaws and thus co-operates with the external pterygoid in triturating the food. The two pterygoid muscles arising so near each other and passing in different directions, the one downwards, and the other upwards and outwards, a triangular space is left between them, containing a quantity of fat, the inter- nal maxillary artery and vein, the inferior dental and gus- tatory nerves, and a portion of the parotid gland. The in- ternal maxillary artery occasionally passes between the origins of the external pterygoid muscles, as it is about en- tering the spheno-maxillary fossa. COMBINED ACTION OF THE MUSCLES OF MASTICATION. The conjoint action of these muscles is the effective agent in mastication. The masseter and temporal are principally employed in raising the lower jaw to the upper,, and thus dividing the food, while the pterygoid in rotating the lower jaw upon the upper, produces the grinding motion, and thus reduces the food to the smallest portions, suitable for deglutition. The anterior layer of the 298 ORGANS OF INSAUVATION. masseter and the posterior fibres of the temporal can also as- sist the pterygoid in the grinding process, while the buccina- tor comes in to their aid by keeping the food under the teeth. So that the whole are so adapted to each other as to act in the utmost harmony for the most perfect performance of the function of mastication. Blood-vessels, (Fig. 'TS.) — The arteries supplying the muscles of mastication come from the temporal, the external and internal maxillary arteries, and are named according to the muscles they supply, as the temporal, masseteric, and pterygoid branches. The veins correspond to the arteries and return the blood into the external jugular. Nerves, (Fig. 74.) — The nerves supplying the muscles of mastication come from the fifth and seventh pair. The motor division of the inferior maxillary branch of the fifth, seen in the zygomatic fossa, sends off five muscular branch- es, i. e. the two deep temporal, masseteric, buccal and ptery- goid, going to the muscles of the same name.* The portio dura or facial nerve is a branch of the seventh, which also supplies the muscles of mastication. It is situated in the substance of the parotid gland, anastomoses freely with the fifth, and is described more minutely under the head of organs of expression, which see. SECTION VII. ORGANS OF INSALIVATION, COMPRISING THE SALIVARY GLANDS. The salivary glands are six in number — three on each side of the face, i. e. the parotid, submaxillary , and sublin- gual. These glands belong to the conglomerate order, that is, they consist of numerous little follicles, (Fig. 85, B,) averaging about the one-twelve-thousandth of an inch in diameter, surrounded by a plexus of capillary blood-vessels, and presenting the appearance of a multitude of small granules — each being a gland in miniature, and each, conse- quently, having its own artery, vein, and excretory duct. It is by the combination of these various little excre- *See inferior maxillary nerve, under the head of nerves supplying the teeth, for a more minute account. ORGANS OF INSALIVATION. 299 tory ducts that one common duct is formed, whose office is to carry the saliva, furnished by these glands, into the mouth. A FIG. 85. B These salivary glands are developed from the mucous membrane of the mouth, which being reflected in the form of a tube, sends off bud-like processes whose ultimate ter- minations constitute the follicles just described. 1. The Parotid. Dissection. — This gland, so called from its situation about the ear, (^apa, near, or$ <*toft the ear,) is brought to view by the same dissection, for exposing the organs of prehension. It is covered by a dense fascia, the fascia superficialis, continued from the neck, which sends down into its substance numerous processes which serve to sep- arate its granules, and conduct to it its blood-vessels. This fascia must be separated from its strong attachment to the cartilaginous portion of the meatus externus, and removed, when the parotid will be fairly exposed. It presents a pale, rough, granulated surface, and is the largest of the salivary glands. It has no regular figure, but occupies the space reaching from the zygoma above, to the angle of the jaw below ; and from the mastoid process and sterno-cleido mastoid muscle behind, to a short distance over the mas- seter muscle in front — while in depth, it passes behind the FIG. 85, A represents the Salivary Glands. 1 Parotid gland, 2 Duct of Steno, 3 Submaxillary gland, 4 Duct of Wharton or submaxillary duct, 5 Sublingual gland. FIG. 85, B represents a lobule of the parotid gland of a new-born infant injected with mercury— magnified fifty diameters. 300 ORGANS OF INSALIVATION. ramus of the jaw, extends back to the styloid process, which, with its muscles, it envelops — is in contact with the inter- nal carotid artery, jugular vein, and eighth pair, or par- vagum nerves, and finally fills the posterior part of the* glenoid cavity of the temporal bone. Each of the granules composing this gland has, as already stated, an excretory duct, which, uniting with its fellows, forms one common duct called the parotid duct, or the duct of Steno, which is seen issuing from the gland at its anterior and posterior part, and is then traced passing over the masseter, about an inch below the zygoma, and through a quantity of soft lobulated fat, on the anterior edge of this muscle. It then pierces the buccinator at its upper part, opening into the mouth by a papilla (some- times there is none) opposite the second or third molar tooth of the upper jaw. A line drawn from the lobe of the ear to a point midway the root of the nose and lower margin of the upper lip, will give the direction of the parotid duct. This duct has two coats — an outer of condensed cellular, and an inner of mucous membrane. Between the zygoma and this duct, a small glandular mass is occasionally seen, having a small duct which either unites with the duct of Steno, or enters separately into the mouth. It is called the socia parotidis. Function. — The use of this gland is to secrete the larger portion of the saliva with which the mouth is supplied, and which is carried thither by the duct of Steno. 2. The Submaxillary Gland— (Fig. 85.) Dissection. — Make an incision along the base of the lower jaw, from the chin back to the angle, and along the ramus, the same as for the organs of prehension. Make a second incision along the median line at the upper part of the neck as far as the hyoid bone, commencing at the lower portion of the symphysis menti, and turn down the skin obliquely towards the clavicle. This exposes the broad muscle of the neck, the platysma myoides, and the superfi- cial cervical fascia. Turn these down, and the submaxil- lary gland is exposed. This gland is second in size to the ORGANS OF INSALTVATION. 301 parotid — is covered by cellular structure, and surrounded by lymphatic glands. It is of an oval shape, and pale color, and occupies a triangular space at the upper part of the neck, bounded anteriorly by the base of the lower jaw — posteriorly and internally by the tendon and ante- rior belly of the digastric muscle- — externally by the stylo maxillary ligament, and the pterygoideus internus muscle. The structure of the submaxillary is the same as the parotid, consisting of granules having each an excretory duct, which unite together into one common duct, called the duct of Wharton, This duct leaves the gland at its an- terior or middle portion, and winds above the mylo-hyoid muscle, between it and the hyoglossus, thence passes for- wards between the genio-hyo-glossus and sublingual gland, the latter of which it touches, and finally ends in a prom- inent papilla, by an open orifice, on either side of the frenum linguae. This duct has thinner walls, but a larger calibre than that of the parotid. It is about two and a half inches long, and is accompanied by the gustatory nerve. function. — To secrete saliva, which is carried by the duct of Wharton into the mouth. If this duct, from any cause, be obstructed, the saliva accumulates on the under surface of the tongue, beneath its tip, forming a tumor called ramula. 3. The Sublingual Gland— (Fig. 85.)— This gland, oblong in shape, and of all the salivary glands, smallest in size, is seen by raising the tip of the tongue, and, as its name im- plies, is on the under surface of its anterior and lateral part. It is covered by the mucous membrane, and rests on the mylo hyoid muscle. It is related to the genio-hyo-glossus and duct of Wharton internally, and is connected behind with a pro- cess of the submaxillary gland. Its excretory ducts do not form a common duct, but have been seen to enter the mouth separately by fifteen or twenty small orifices, on a kind of fold or crest of the mucous membrane, between the tongue and inferior bicuspid and canine teeth. The ducts, some of them, enter the duct of Wharton. Function. — The same as the parotid and submaxillary. 302 OKGANS OF INSALIVATION. Blood-vessels. — The salivary glands are abundantly sup- plied with blood-vessels. The arteries going to the parotid come from the external carotid (Fig. 73) and its branches the facial, superficial temporal, transverse facial, and an- terior and posterior auricular. The veins take the same direction as the arteries, .have the same names, and termi- nate in the jugular. The submaxillary is supplied by the facial and lingual. The sublingual gland has its supply from the sublingual and the submental branches. The veins correspond to the arteries. Nerves. — The parotid is supplied with nerves from the auricular branch of the inferior maxillary, (Fig. 74,) and auricular branch of the cervical plexus; the facial, and filaments of the sympathetic, from those of the external carotid artery. The submaxillary gland is supplied from the submaxillary ganglion, the lingual, and mylo-hyoid branch of the inferior dental nerve. Saliva is a term indiscriminately applied to the secre- tions furnished by the salivary glands, and, until very recently, has been supposed to be of the same character, whatever its source. It was generally examined mixed with the other fluids of the mouth, so that its precise char- acter could not be definitely fixed. It was regarded as alkaline, in a state of health, which more recent observa- tions confirm ; while the fluids of the buccal mucous mem- brane have been found to be acid. The microscope reports the saliva to contain minute corpuscles, and large epithelial scales derived from the mucous membrane of the mouth. Its chemical constitution is furnished by the chemists Frerichs and Wright, two of the most recent authorities, and whose analysis is re- garded as the most accurate. The former makes saliva to consist in a hundred parts : of water, 994.10; solid matters, 5.90; ptyaline, 1.41; mucus and epithelium, 2.13; fatty matter, .07; sulpho-cyanide of potassium, .10; alkaline and earthy chlorides and phosphates, 2.19. Wright's analysis is in a hundred parts: water, 988.10; solid matters, 11.90; ptyaline, 1.80; mucus and epithelium, ORGAN'S OF DEGLUTITION. 303 2.60; fatty matter, .50; albumen with soda, 1.70; sulpho- cyanide of potassium, .90; alkaline andi earthy salts, 3.20; loss, 1.20. Ptyaline is the term applied to a substance upon which the peculiar properties of the saliva are made to depend, and is regarded as albuminous in its character. The ptya- line of Wright, however, differs from that of other observers. Now the experiments of M. Bernard seem to show that saliva is not only not the same, but presents quite different properties and uses, as obtained from the parotid, submax- illary, and sublingual glands. That from the parotid is found to be thin, watery, abundant, (varying, however, according to the food,) readily penetrating substances, and believed to be especially designed to aid in mastication and assimilation, and is the fluid chiefly concerned in form- ing the food into a bolus, for its onward passage from the mouth into the pharynx. The saliva from the sublingual is described as "viscous and adhesive, incapable of penetrating substances, but ad- mirably adapted to cover their surface with a viscid coat- ing, which much facilitates their being swallowed," and is the fluid especially concerned in deglutition. This gland is said to remain quiet during mastication, but to begin to act as soon as deglutition commences. The submaxillary gland furnishes a saliva partaking of the characters of both the former, and supposed to be especially concerned with the sense of taste, diminishing the pungency of sapid bodies, and reducing their cohesion. SECTION VIII. ORGANS OF DEGLUTITION. The organs of deglutition consist of the muscles forming the floor of the mouth, the pharynx, soft-palate, and tongue. THE MUSCLES. Dissection. — The same incisions are required as were resorted to in exposing the submaxillary gland. 304 ORGANS OF DEGLUTITION. Digastricus Musde—fa, twice, ywrcp, belly.) This mus- cle is composed of two fleshy bellies, an anterior and poste- rior, with a round tendon in the centre. It is situated below the base of the lower jaw, at the anterior and lat- eral portions of the neck. It arises from the groove on the inner side of the mastoid process of the temporal bone, descends fleshy, obliquely forwards and inwards, till it ap- proaches the os-hyoides, when it becomes tendinous, per- forates the stylo-hyoid muscle, connects itself by a strong fascia— sometimes by a ring-like pully— to the hyoid bone, FIG. 86. and then passes for- ward again fleshy, forming the anterior belly, to be inserted into a depression, close to the sym- physis, on the in- ner side of the lower jaw. Function. — To draw down the lower jaw, and to elevate the os-hyoides, tongue and larynx, when the mouth is closed. When the anterior belly acts it can draw these parts for- wards. When the posterior acts they are drawn backwards. It exerts, by these varied actions, great influence over deglutition. Mylo-Jiyoideus , (/u&.q, a molar or grinder,) Fig. 86, is a broad, triangular muscle, forming the floor of the mouth, FIG. 86 represents the muscles at the base of the lower jaw, and upper and front part of neck. 1 Posterior belly of the digastricus. 2 Its anterior belly 3 Ligamentous loop through which it plays. 4 Stylo-hyoideus. 5 Mylo- hyoideus. 6 Genio-hyoideus. 7 Tongue. 8 Hyo-glossus. 9 Stylo-glossus. 10 Stylo-Pharyngeus. 11 Sterno-cleido-mastoideus. 12 Its sternal origin. 13 Clavicular attachment. 14 Sterno-hyoideus. 15 Sterno-thyroideus. 16 Thyro- hyoideus. 17 Anterior belly of omo-hyoideus. 18 Posterior belly of omo- hyoideus. 19 Anterior edge of trapezius. 20 Scalenus anticus. 21 Scalenus posticus. 22 Scalenus medius. ORGANS OF DEGLUTITION. 305 and fully exposed on removing the anterior belly of the digastric. It arises from the myloid ridge on the inner side of the lower jaw, and descends inwards and backwards to be inserted into the base of the os-hyoides, and along with its fellow into the middle tendinous line, between that bone and the chin. Function. — To bring the os-hyoides forward and pro- ject the tongue. This muscle is covered by the digastric muscle, the submaxillary gland, the platysma and fascia, and lies upon the genio-hyoid, hyo-glossus, and stylo- glossus muscles — the duct of Wharton, lingual and gus- tatory nerves, and sublingual gland. Eemove this muscle by dividing it on either side, and we see the next in order, i. e. Genio-hyoideus , (ysvswv, the chin,) Fig. 8*7- It arises from the posterior mental tubercle above the digastric, by a small tendon, and descends backward to be inserted into the base of the os-hyoides. Function. — To bring the os-hyoides forward, and to protrude the tongue against the incisor teeth, or out of the mouth. Genio-Jiyo-glossus , „ (yxwtfora, the tongue,) is seen by removing • the genio-hyoideus. It is a' triangular muscle_, and arises by a small tendon from the posterior men-l tal tubercle, above the genio-hyoideus and be- low the frenum linguae, and is inserted into the tongue along the mesial line its whole length, and into the body of the os-hyoides. Its fibres radiate in different directions; some FIG. 87 represents a side view of the Tongue and its principal Muscles. 1 Mastoid process. 2 Coronoid process. 3 Stylo-glossus muscle. 4 Hyo- glossus. 5 Genio-hyo-glossus. 6 Genio-hyoideus. 7 Symphysis menti. 8 Styloid process. 20 306 SOFT PALATE. pass forward to the tip of the tongue; others backward, while another set are in the middle. Function. — The anterior fibres can depress the tip of the tongue, the posterior bring forward the os-hyoides and protrude the tongue, while the middle set can make it con- cave from side to side. Hyo-glossus (Fig. 87) is a quadrilateral muscle, arising from the body and whole of the cornu of the os-hyoides, and inserted into the side of the tongue between the stylo- glossus and the lingualis. Function. — To depress the sides of the tongue, and thus render its dorsum convex. Stylo-glossus (Fig. 87,) arises tendinous and slender from the styloid process near its apex or free extremity, and from the stylo-maxillary ligament, and is inserted in two por- tions, into the side of the tongue — one portion blending with the hyo-glossus, and the other being continued for- ward to the tip of the tongue. Function. — To raise the tip of the tongue against the incisor teeth, and draw it backward, and to one side. Stylo-Jiyoideus (Fig. 86) is a small, delicate muscle, arising near the base of the styloid process, on its outer side, pass- ing obliquely forwards and inwards, parallel to the poste- rior belly of the digastric, whose tendon perforates it. It is inserted into the body of the os-hyoides. Function. — To draw back the os-hyoides and tongue, and thus assist the posterior belly of the digastric. A ligament, called stylo- hyoid, often accompanies this muscle, and is sometimes found ossified. SOFT PALATE. The palate has been divided into hard and soft. The hard is composed of the palatine plate of the palate bones. The soft palate is attached to the posterior mar- gin of the hard, and consists of a dense aponeurosis, muscles and glands, enclosed in mucous membrane. The soft palate, (velum pendulum palati,*) on depressing the lower jaw, is seen at the posterior part of the mouth, sus- pended transversely in the form of a membranous curtain. SOFT PALATE*. 307 * This pendulous portion is the vertical or inferior part, while above, the soft palate is extended backward on a level with the hard, forming what is called its horizontal portion, and thus increasing the palatine arch. The velum palati is a membranous valve separating the mouth from the pharynx and posterior nares, and, in fact, acts the part of a double FIG. valve. In deglutition, this velum is raised and applied to the posterior nares, to pre- vent the food from passing in this direction when entering the pharynx, and after the food has entered the pharynx it falls down into its original position, and prevents the return of the food into the cavity of the mouth. The velum presents a broad, quadrilateral shape, and has two sur- faces— the one looking towards the tongue — the lingual; the other towards the nose — the nasal surface. The lin- gual surface presents, along its middle, a white line, called the raphe ; and from the centre of the velum there is seen a depending portion called the uvula, which divides it into two lateral halves. In the raphe is situated that congeni- tal division of the velum called cleft palate. On either side of the uvula the velum presents two lateral curvatures, an anterior and posterior, called the anterior and posterior lateral half arches. The anterior half arches proceed from the base of the uvula, outward, having their concavit}r downward to the sides of the tongue. The posterior half arches, proceeding also from the uvula, pass downward and backward to the sides of the pharynx. The space between the anterior and posterior half arches is called the fauces, and is occupied by the tonsils. The opening FIG. 88 represents the muscles of the Soft Palate, a Roof of the mouth ; b b Levator palate ; c Cuneiform portion of the sphenoid ; d d Eustachian tubes; t Circumflexus, or tensor palati muscle ;/ Azygos uvula; gg Palato pharyngeus. 308 SOFT PALATE. between the anterior half arches is the isthmus of the fauces. The tonsils or amygdalae, (o/wySatoa, an almond,) situated as just stated in the fauces, consist of mucous follicles col- lected together in an almond-like shape, and vary much in size. In some they are scarcely seen — in others they fill up the whole fauces. Their inner surface is free, and full of foramina, which lead into the mucous follicles, that have been mistaken for ulcerations. Their external surface is cov- ered by an aponeurosis, and the superior constrictor of the pharynx. They are very subject to inflammation, constitu- ting quinsy or tonsilitis, and to chronic enlargements requir- ing extirpation. Their posterior surface corresponds to the angle of the jaw, and they are in relation in front with the facial artery, behind with the internal carotid, and on the outer side with the external carotid, separated by the supe- rior constrictor of the pharynx, and some cellular tissue. The structure of the soft palate consists, as stated, of an aponeurosis, muscles, blood-vessels and nerves, surrounded by mucous membrane. The aponeurosis is a strong, dense, and fibrous tissue, regarded as continuous with the fibrous structure of the septum narium, the nasal fossae and Eustachian tube, and constituting the frame work of the palate. The Muscles (Fig. 88) of the soft palate are five pairs, i. e. the levator and tensor palati, constrictor istlimi faucium, palato-pJiaryngeus , and azygos uvulae. Dissection. — Open the pharynx from behind, by separat- ing it from the cervical vertebras, which remove, and then take off the mucous membrane of the palate, when its mus- cles will be exposed. 1. Levator palati is a moderately thick and round mus- cle, and arises in front of the foramen caroticum, from the extremity of the petrous bone, and back of the Eustachian tube, then descends by the side of the posterior nares, and is inserted broad into the soft palate as far as its median line. Function, to raise the palate. 2. Tensor palati, or circumflexus, is a slender muscle upon SOFT PALATE. 309 the outside of the levator, and arises fleshy from a fossa at the root of the internal pterygoid plate, from the spinous process of the sphenoid bone, and front part of the Eustachian tube, and descends along the pterygoid plate, becoming a flat tendon as it reaches the hamulus, round which it turns. It finally expands by inserting itself into the aponeurosis of the palate, and according to some, into the hard ^palate also. Function, to spread the palate. 3. Constrictor-isthmi-faucium or palato-glossus, so called from its constricting or closing the opening to the fauces, occupies the anterior half arch of the palate and is in front of the tonsil. It consists of a small bundle of fibres, broader at the extremities than in the centre, arises from the lower surface of the velum, and descends to be inserted into the side of the tongue. Function, to raise the tongue, or depress the palate, and close the fauces. 4. Palato-pharyngeus occupies the posterior half arch of the palate, and arises, in common with its fellow, broad, from the lower surface of the velum, and passing down- ward and backward, behind the tonsil, is inserted into the pharynx at its side and back, between the middle and lower constrictors, and into the border of the thyroid cartilage. Function, to raise the pharynx as deglutition begins, and to depress the palate. 5. Azygos-uvulce is not, as its name implies, a single muscle, but a pair of small symmetrical muscles, placed side by side on the median line, and arising from the poste- rior spine of the palate bone, or more correctly from the aponeurosis, continuous with the spine. It descends ver- tically to constitute the greater portion of the uvulae. Function, to elevate and shorten the uvula. Blood-vessels. — The arteries of the soft palate are the superior and inferior palatine branches of the internal maxillary and facial. The veins correspond with the arteries. The nerves are the palatine branches of the superior max- illary of the fifth pair, coming from Meckel's ganglion, also branches from the glosso-pharyngeal. 310 THE TONGUE. THE TONGUE. The tongue is arranged here among the organs of degluti- tion, though it performs a variety of other offices equally important in connection with other functions ; as, for in- stance, it is concerned in prehension, suction, mastication, articulation, playing upon wind instruments, and is the special organ of taste. It is an organ of motion \ its great bulk consisting of muscular structure. It is an organ of sensation, both special and general, being most abundantly supplied with nerves ; and it is also an organ of secretion ; hence the im- portance of this body considered in any and every aspect. Its situation in the cavity of the mouth, and within the F,G. 59. dental arch, in the state of rest, is familiar to all. It is kept in its position by ligaments and muscles, which attach it to the hyoid bone, the styloid pro- cesses and the lower jaw. It has, however, free motion at its tip and sides. The posterior portion, connecting it with the os-hyoides, is called its base, the middle portion the body, and the anterior part the tip. It has two surfaces, an upper and lower; the upper is called the dorsum of the tongue. Its size is very variable in different individuals. TV but is always in proportion to the curve of the lower jaw, and never fills the entire cavity of the mouth when the jaws are closed. The anterior and middle part is hori- FIG. 89 represents a view of the Upper Surface of the Tongue, a a Poste- rior lateral half arches; 6 Epiglottis; c c Mucous membrane, extending from root of tongue to epiglottis; d Foramen coecum of Morgagni; e Lenticular papillae; /Papillae filliformes; g Conical papillae; h Point of tongue; i i Fungi- form papillae. THE TONGUE. 311 zontal, while the posterior makes a somewhat vertical bend down to the os-hyoides. This account of its direction is true when the tongue is kept within the mouth, hut when it is protruded, the os-hyoides rises, and the whole is then on nearly the same horizontal level. The form of the tongue is somewhat of an ellipse. Its upper surface or dorsum presents a very rough aspect from numerous eminences called papillae, (papilla, a nipple.) These papilla? are various in size, and have received dif- ferent names. Those at the hase, arranged in the shape of the letter V, are the papillce maximce. (Fig. 89.) They are ahout nine in numher, though as many as sixteen and twenty are mentioned. They are the largest in size, and present two rows, forming at their point of union a hlind opening called the foramen ccecum of Morgagni, regarded as the receptacle of mucous secretion from the follicles. These papillae maximae resemble a cone, have their base above and free, while the apex is below and fixed in a cup-like cavity, whence they are also called calyciformes. Within this cup a fossa, or circular trench, is seen surrounding the papilla, from which also the name of circumvallatce, is derived. The papillce mediae, or fungiformes, the next in size, are found irregularly scattered over the dorsum of the tongue, and some are seen at the tip. They are easily re- cognized by the rounded and flattened tops resting on a narrow pedicle, and having a direction backwards. The papilla! villosce or conical, and the filiform, are the smallest and most numerous; they cover the whole surface of the tongue, being scattered among all the others, and are most abundant at the tip. Blood-vessels of papillae. — The microscope of Mr. Nasmyth discovers the elements of the papillae to consist of capillary vessels and loops of terminal nervous filaments, connected by an areolo-fibrous tissue. The capillaries are found to pro- ceed from a small artery running through the centre of the papillae, (Fig. 90, B,) and then ending in a vein which re- turns along the course of the artery. A variety is observed 312 THE TONGUE. in the capillaries of the different papillae — in those of the conical papillae of the foetus a coarse net-work is observed, and a vascular ring surrounding the apex of each papilla, giving the appearance of an aperture. In the filiform papillae, the capillaries are seen as a single loop, (Fig. 90, A,) while in the papillae maximae or calyciformes, (Fig. 90, A?) they are more tortuous and of the plexus form. Behind the papillae maximae some eminences are ob- served having the same arrangement as these papillae. They A FIG. 90. were formerly considered among the pa- pilla3, but are now regarded as glands. They have perforations which are visible to the eye, and being found to have the same structure as the parotid, are considered salivary and not mucous glands. The upper surface of the tongue has beneath its mucous coat a dense membrane, which resembles the corium of the skin, and is called the papillary membrane from its giving support to the papillae. In some instances it is almost as hard as cartilage. It is divided along the median line by a FIG. 90, A represents the Papillae on a part of the surface of the Tongue of an adult, and shows the manner in which the vessels are distributed. « Pa- pilloe maximae or calyciforme. 6 6 The groove around it. c Papillae filiformes, or thread-like papill®. d Conical papillae. FIG. 90, B represents a conical Papilla, having at its extremity a An aperture* The distribution of its vessels is also seen. THE TONGUE. 313 raphe, which is a vertical septum of ligamentous matter, making the tongue consist of two equal and symmetrical parts. The anterior third of the tongue is the only portion free on its lower surface, all the rest being attached by mus- cles. On this surface is noticed, along its middle, a furrow from the posterior part of which a fold of mucous mem- brane passes to the posterior surface of the symphysis menti. This fold is called the frenum linguce, and is the part concerned in the "tongue-tie" of children, where it is too short and requires division. The ranine veins are plainly seen on each side of this furrow. Muscles of the Tongue. — The muscles of the tongue (Fig. 87) consist of four pair, which have been given at the beginning of this section, except one, the lingualis. This is the intrinsic muscle of the tongue, and consists of a slender fasciculus of fibres, arising indistinctly among the yellow cellular tissue at its base, and passing forward between the hyo-glossus and genio Jiyo-glossus, to the tip. Its fibres run in different directions — being transverse and vertical, as well as longitudinal ; hence the terms transverse lingual, and vertical lingual muscles. The superficial fibres of this muscle are closely connected with the dense papillary membrane or corium, which is a kind of skeleton upon which they, with the other fibres, act in effecting changes both in the form and density of the tongue. Thus, by means of this extensive muscular appara- tus, the tongue has the power of moving in every possible direction — of keeping the food beneath the teeth, and of passing it from the mouth into the pharynx — thereby per- forming a most efficient part in mastication, as well as deglutition. Blood-vessels of the Tongue9 (Figs. T3, 91.) — The arteries come principally from the lingual, a branch of the external carotid, and injections seem to show that the arteries be- longing to either half of the tongue advance to its vertical septum, and then stop — those of the one side having no anastomosis with those of the other, being effectually pre- 314 THE PHARYNX. vented by the strong ligamentous barrier placed between. It is very important, in the excision of tumors, or other op- erations on one side of the tongue, to know there is no danger of hemorrhage from the vessels of the opposite side. Nerves, (Fig. 91.)— The nerves of the tongue come from three sources, and are large. 1. The Gustatory branch of the fifth pair goes to the papilla, and gives common sensi- bility, and is also supposed to be the special sense of taste. FIG. 91. 2. The Lingual, or ninth pair, goes to the muscles and gives the power of mo- tion. 3. The Gloss o-pliaryn- geal supplies the follicles, glands, and mucous mem- brane of the tongue, and is regarded as a compound nerve, having both sensa- tion and motion. This nerve connects the tongue with the pharynx and la- rynx. A branch of the fa- cial nerve has also been found in the tongue, but was seen only on one side. THE PHAKYNX. The Pharynx (Fig. 92) is situated at the posterior part of the mouth, behind the nares, in front of the cervical vertebrae, and below the base of the skull, extending infe- FIG. 91 represents the side of the Tongue, with the relations of its vessels and nerves, a Hyoglossus muscle. 6 c Section of the lower jaw at its symphysis. d Genio-hyo-glossus. e Genio-hyoideus. /Left edge of mylo-hyoideus. g Com- mon carotid artery, and its division into external and internal, h Trunk of superior thyroid, i Lingual artery, j Constrictor medius muscle, k Hori- zontal portion of lingual artery. / Its oblique or terminating portion, m The ranine artery, n Trunk of the facial artery, o The three posterior branches of external carotid, p Trunk of ascending pharyngeal. r Terminus of ex- ternal carotid into internal maxillary, and temporal arteries, s Gustatory branch of the fifth nerve, *its communication with the lingual, t Glosso-pha- ryngeal nerve. M Hypoglossal or ninth nerve, v Duct of Wharton, or sub- maxillary duct, to Sublingual gland. THE PHARYNX. 315 FIG. 92. riorly to the fourth, or fifth cervical vertebra behind the lower part of the cricoid cartilage, where it ends in the ossophagus. Dissection. — Make a transverse incision at the lower part of the neck, through the trachea and oesophagus; turn these up with the vessels and nerves, to the base of the cranium, and then detach the head from the spine, by disarticulating at the atlas, or, which is more convenient, by sawing between the atlas and dentata — now stuff the pharynx with curled hair, or tow, or cot- ton, and it is prepared for dis- playing its muscles. The pha- rynx is a musculo-membranous sac or cavity, somewhat of an oval form, attached superiorly to the cuneiform process of the oc- cipital bone, by a strong apon- eurosis; posteriorly, to the deep muscles of the neck and cervi- cal vertebrae, by a loose cellular tissue; anteriorly, to the internal pterygoid plate of the sphenoid bone, hamular process, posterior part of the upper jaw, and mylo-hyoid ridge of the lower jaw — also to the sides of the tongue, the cornua of the os-hyoides, and the sides of the cricoid and thyroid cartilages. There is, besides, a lateral connection with the petrous bone. By these several connections the pharynx is kept constantly open, and its walls pre- vented from falling together. Structure. — The pharynx consists pf three coats, i. e. an outer or muscular, a middle or cellular, and an inner or mucous — in addition to which, it abounds in blood-vessels and nerves. FIG. 92 represents a view of the Constrictors of the Pharynx, and an ante- rior view of the Palate. 1 1 Superior constrictor of the pharynx. 2 2 Mid- dle constrictor. 3 3 Inferior constrictor. 4 4 Levator palati. 5 Uvula. 6 6 Anterior half arch. 7 Circumflexus, or tensor palati muscle. 316 THE PHARYNX. The muscles (Fig. 92) cover the back -and sides of the pharynx in one uniform membranous sheet or layer, and are called constrictors. They are three in number, the inferior, middle, and superior constrictors of the pharynx. These are symmetrical muscles, lying upon either side, and connected with the tendinous line or raphe, which runs along the centre of the back part of the pharynx. Constrictor pliaryngis inferior, arises from the inferior cornu, and posterior ala of the thyroid cartilage, and from the side of the cricoid. Its fibres radiate, (some ascending, and others transverse,) to be inserted into the raphe on the back of the pharynx, along with its fellow. The superior fibres overlap the middle constrictor. The superior la- ryngeal nerve passes along the upper, and the inferior laryngeal beneath the lower border of this muscle. Constrictor pliaryngis medius — partly covered by the last, and of a triangular shape, arises from the appendix and cornu of the os-hyoides, and from the posterior thyro-hyoid and styloid ligaments. Its fibres ascend, run transversely, and descend. It is inserted into the mesial line, and by its ascending fibres, into the cuneiform process of the occipital bone. Constrictor pharyngis superior is above the last, and separated from it by the stylo-pJiaryngeus muscle, and glosso-pharyngeal nerve. It surrounds the upper and pos- terior part of the pharynx, and arises from the internal pterygoid plate, from the upper jaw, behind the last molar tooth ; from the pterygo maxillary ligament ; from the side of the base of the tongue, and from the posterior portion of the mylo-hyoid ridge. From this extensive origin, the fibres proceed backwards and upwards, and are inserted into the middle line, and cuneiform process of the occipi- tal bone. - r*' Function. — The constrictor muscles are the prime agents in deglutition, and conduct the food, by their successive contractions, from the pharynx into the oesophagus. Stylo-pliaryngeus is a slender muscle arising from the root of the styloid process. It passes to the side of the THE PHARYNX. 317 pharynx, between the upper and middle constrictors, and is inserted into the cornu and posterior margin of the thy- roid cartilage. Function. — To raise, dilate, and shorten the pharynx, so as to receive the food. It will also elevate the larynx. The middle coat consists of cellular tissue, called the pharyngeal aponeurosis, which is stronger along the mid- dle line where it gives attachment to the constrictor mus- cles, than elsewhere, and is the connecting structure be- tween the outer or muscular, and mucous or internal coat. This coat, being a continuation of that lining the cavity of the mouth, will be considered in connection with it. Cavity of the Pharynx. — Dissection. — Make an incision through the middle tendinous line on the back part of the pharynx, and this cavity will be exposed. In front will be seen the velum and uvula, and opening into it will be noticed seven foramina; at its upper part are the two pos- terior nares, on each side of these are the Eustachian tubes, in front is the isthmus of the fauces, and below we see the glottis, and the commencement of the oesophagus. The Eustachian tubes are found at the posterior part of the in- ferior turbinated bone, and as just stated, on each side of the nares. Their mouth is circular, and large enough in most cases to admit the end of the little finger. They lead to the ear, and conduct the air from the pharynx into the cavity of the tympanum. Their direction is upwards, out- wards, and backwards to the tympanum, occupying in their course the pterygoid fossa, and having in two-thirds of their extent a thick cartilaginous structure, the balance being composed of bone. These tubes are lined by the mucous membrane continued from the pharynx, and when this is inflamed they become thickened and obstructed, this being a frequent cause of deafness. Blood-vessels, (Fig. fS.) — The arteries supplying the pharynx are the superior and inferior pharyngeal, tHe for- mer a branch of the internal maxillary, the latter a branch of the external carotid. The palatine and superior thyroid 318 THE MOUTH. also send some small twigs. The veins, after forming the pharyngeal plexus y return into the jugular and superior thyroid. Nerves. — The nerves of the pharynx are the c/losso- pharyngealj (Fig. 91,) the pharyngeal "branch of the par vagum, all belonging to the eighth pair, and branches from the superior cervical ganglion of the sympathetic. SECTION IX. THE MOUTH. The mouth, (Fig. 93,) situated at the commencement of the digestive tube, is composed of the organs of prehension, FlG 93 mastication, insaliva- tion, and part of those of deglutition. Hence it is evident that it con- sists of an apparatus both complicated and various. Having con- sidered all the organs forming the mouth, successively and in de- tail, it now seems proper to look at them for a moment collect- ively in their several relations to the mouth as a whole, and in their united and harmonious action in the dis- charge of the various functions they are called upon to perform. The cavity of the mouth is bounded superiorly by the palatine processes of the superior maxillary and palate bones, which constitute its roof; infer iorly by the mylo- FIG. 93 represents a view of the cavity of the mouth, a Superior lip turned up. 6 Froenum of the upper lip. c Inferior lip turned down, d Frsenum of the lower lip. e e Internal surface of the cheeks. // Point where the duct of steno enters the mouth, g Roof of the mouth, h Anterior portion of the lateral half arches, i Posterior portion of the lateral half arches, j Velum pendulum palati. k Tonsils. I Tongue. THE MOUTH. 319 hyoid muscles, forming the floor ; anteriorly by the lips ; posteriorly by the soft palate, and laterally by the cheeks. Dissection. — To expose the cavity of the mouth, make an incision through its angles, carried laterally through the cheeks, dividing the buccinator, masseter and insertion of temporal muscles ; then, in sawing through the lower jaw on one side, the cavity will be fully laid open for examin- ation. The tongue, teeth, gums, velum, uvula, tonsils, and sublingual glands, are some of the contents already de- scribed of this cavity ; the whole of which, as well as the cavity itself, has one common covering, i. e. the mucous membrane of the mouth, which extends into the pharynx, and is continuous with the great gastro-pulmonary mucous membrane. The mucous membrane of the mouth and pharynx has already been considered in a general way in the description of this elementary tissue, under the head of alphabet of anatomy. But there are some modifications in its course, not there mentioned, which require notice. It will be recollected that mucous membrane is usually soft, pulpy, easily torn, and when deprived of blood, of a pale, grayish, or ashy hue. Now, in the mouth and on the lips this membrane has considerable firmness, and pre- sents a distinct epithelium, corresponding to the cuticle of the skin. The nucleated cells of which this epithelium is at first composed, as they advance to their full development gradually lose their nuclei and present the form of scales, so that the epithelium of the mouth is called squamous. As the mucous FIG. 94. membrane passes from the posterior surface of the lips to the front portions of the alveolar pro- cesses of the upper and lower jaw, it is folded or duplicated, Fio. 94 represents a Tiew of the inner side of the Lips, a a Ducts of Steno or parotid ducts. 6 6 Labial glands. 320 THE MOUTH. FIG. 95. and these folds receive the name of frena or hridles of the lips. Beneath the mucous layer of the lips are situated the labial glands. These consist of small spheroidal granules. Like the parotid and the rest of the salivary glands, they lie close to each other, but are distinct, and have each a distinct excretory duct, and open by a separate ori- fice on the posterior surface of the lips. Hence they are regarded as true salivary, and not mucous \a glands, (Fig. 94.) The vascularity of the lips, as shown under the microscope of Mr. Nasmyth, is exhibited in Fig. 95. A represents a part of the mucous membrane on the in- ner side of the upper lip of a fetus, minutely injected, mag- nified 40 diameters, a a Papilla?, which become smaller towards the middle of the figure, b Capilla- ries forming a plexus with small meshes, c The capillary plexus coarser, the meshes larger and corresponding to the situation of the submucous glands. B also magnified 40 diameters, repre- sents a portion of the free edge of the upper lip of a human foetus, and shows the manner in which the capillaries are arranged in the papilla). The mucous membrane in pass- ing from the lips over the alveolar processes, to get behind the teeth, undergoes a most re- markable and important change, being transformed into the gums. THE GUMS. 321 The gums are distinguished by their thickness, by their density, being almost cartilaginous ; by their intimate ad- hesion with the periosteum of the alveolar processes ; and by their strong attachment to the necks' of the teeth. The vascularity of the gums, as developed by Mr. Nasmyth's microscope, is seen in the annexed figure. A represents the B lower part of the fig- papillae of a part of the gum of an adult, minutely in- jected, magnified 38 diameters, and shows the tortuous course of the capil- lary vessels. B represents a part of the gum and adjacent mu- cous membrane of the human fcetus, magnified 100 di- ameters. In the FIG. 96. A ure are seen the plex- uses formed by the larger vessels ; and in the upper part are seen the papillae. c C shows a portion of the mucous membrane of the gum and palate of the human fcetus, minutely injected and mag- nified *75 diameters. The deeper vessels are the largest, and the spaces in the superficial plexus correspond to the situation of the submucous glands. 322 ALVEOLO-DENTAL-PERIOSTEUM. The gum is traced from the neck of the tooth into the al- veolar cavity, as continuous with, and constituting the alveolo-dental periosteum. In the infant state the gums present on their superior edge a dense, white, cartilaginous ridge, which becomes thinner and thinner as the period of eruption approaches. The failure to undergo this thin- ning process is the not unfrequent cause of great irritation and even of convulsions in teething. In the tissue of the gums, mucous follicles are found, which have been mistaken for glands furnishing the tartar, and have hence been called tartar glands. But it is now settled that the tartar is simply a deposit of calcareous matter from the saliva. Alveolo-dental periosteum. — This membrane is fibrous in structure — is attached to the necks of the teeth- — lines the alveolar cavities — covers the roots — is connected to the blood-vessels and nerves, where they enter the apices of the teeth, and is believed by Mr. Bell, to enter the cavities of the teeth, lining their interior walls, and being contin- uous with, or the same as that of the pulp. It has just been stated that this membrane is believed to be continuous with that of the gums. Others think that the sac containing the pulp, which consists of two coats, after the eruption of the teeth, forms (especially the outer coat) this alveolo-dental periosteum; while Mr. Bell, on the other hand, believes that the sac is entirely ab- sorbed, and that this membrane is the same as the perios- teum, covering the superior and inferior maxillary bones, continued into the alveolar cavities, and from thence re- flected on the roots of the teeth. This membrane is important in maintaining the teeth in their sockets. In tracing the mucous membrane from the gums, we next find it covering the roof of the mouth, the soft palate, the interior of the cheeks, the tongue, and thence follow it into the pharynx. The mucous membrane, covering the roof of the mouth , is characterized by the thickness of its epithelium, the density of its chorion, its strong adhesion to the bone, its whitish color; and the numerous orifices noticed in it, MUCOUS MEMBRANE OF THE MOUTH. 323 especially at its back part. On the median line of the pal- atine arch, the mucous membrane is most strongly attached to the periosteum — while on either side of this line there is interposed a thick layer consisting of glands. These glands are found to be sometimes disposed in regular rows over the palatine arch, and from their being like the labial and parotid, are called the palatine salivary glands. They are in greater numbers behind than in front, and open by many orifices which are visible to the eye. The mucous membrane, lining the cheeks, is a continua- tion of that belonging to the lips, already described. There is also, beneath it, a layer of glands of the salivary order, which cause projections on its surface, and are called the salivary buccal glands. They are precisely like the labial, though smaller, and open by distinct orifices. Two of these glands, from not being situated directly beneath the mem- brane, but placed between the buccinator and masseter muscles, are called the molar glands. Their ducts open opposite the last molar tooth. The mucous membrane of the soft palate is remarkable for its upper or nasal surface presenting the columnar arrangement in its epithelium, while the lower or lingual surface has the squamous form of the mouth. The mucous membrane of the pharynx has a reddish appearance, and is characterized by its density and close adhesion to the periosteum upon the basilar process. It forms a rim around the mouth of the Eustachian tube, and becomes thinner as it traverses the tube towards the cavity of the tympanum. This relation established between the nose and throat, and the Eustachian tubes, by the continuity of the same mucous membrane into these several parts, is regarded as the cause of that deafness which occurs from obstruction in these tubes during coryza and chronic sore throat. Blood-vessels of the Houtli and Pharynx, (Fig. 73.) — The internal maxillary, facial, lingual, and pharyngeal arteries, all branches of the external carotid, are the principal sources whence the mouth and pharynx, with all their organs, are 324 ORGANS OF EXPRESSION. supplied. They have been already detailed. The veins have corresponding names and situation with the arteries, and terminate in the jugular. The nerves (Fig. 74, 91, 9 the inside of the carotid, and above the ophthalmic artery to the optic foramen through which it passes. On enter- ing the orbit it is surrounded by a process of dura mater? which divides into two por- tions, the one being continu- ous with the periosteum of the orbit, the other with the sclerotic coat of the eye. The nerve then enters the back part of the eye through the sclerotic and choroid coats to terminate in the retina. Third Pair} or Motores Oculorum, (Figs. 118, 101,) are FIG. 118 represents the second pair or nerves of sight, the Optic. 1 1 Ball of the eye, the right one has the sclerotic and cervical coats removed to show the retina. 2 Chiasm of optic nerves. 3 Corpora albicantia. 4 Infundibulum. 5 Pons Varolii. 6 Medulla oblongata. 7 Third pair motores oculi. 8 Fourth pair pathetici. 9 Fifth pair trigemini. 10 Sixth pair motores externi. 11 Facial and auditory. 12 Eighth pair pneumogastric, spinal accessory, and glosso-pharyngeal. 13 Ninth pair hypo-glossal. 422 NERVES OF ENCEPHALON. nerves of motion, and arise each from the inner side of the cms cerebri, close to the pons, its fihres heing traced to the locus niger in the cms. These nerves penetrate the dura mater at the posterior clinoid process, and proceed forward along the outer wall of the cavernous sinus to the foramen lacerum superius, through which they pass, and then di- viding into two branches, supply five of the seven muscles contained in the orhit. Fourth Pair of Nerves, Pathetici or TrocMeares, (Fig. 118.) These are the smallest nerves of the brain, not larger than an ordinary strand of cotton, and arise each by two or three filaments from the valve of Vieussens, &nd.processus a cerebello ad testem ; they are very delicate and easily broken, and pursue a long course on the outer margin of the pons, between the cerebrum and cerebellum, to the posterior cli- noid process, where they enter a canal of the dura mater, then proceed along the external wall of the cavernous sinus, at first below the third, then above all the nerves at this point, to the foramen lacerum superius or sphenoidal fissure, through which the last pass to be distributed solely to the superior oblique muscles of the eye. Fifth Pair, Trifacial or Trigemini, (Figs. 118, T4.) — These are compound nerves, having filaments both of sensation and motion, hence they have been called the cranial-spinal nerves. They are the largest of the cerebral nerves, and, according to Dr. Alcock, arise by two roots from an emi- nence, on a longitudinal tract of yellowish matter in front of the floor of the fourth ventricle, which divides inferiorly into two fasciculi, traceable downward to the spinal cord, the one going to the anterior column, the other to the pos- terior. The two roots having this origin, emerge on the side of the pons Varolii, where it is continuous with the crus cerebelli. Here they are separated by a narrow, trans- verse fasciculus. The union of the two constitutes the fifth nerve, which consists of from TO to 100 filaments bound to- gether by pia mater. The nerve passes forward in an oval opening or canal in the dura mater, formed by the separa- tion of the two layers of this membrane, and then expands NERVES OF ENCEPHALON. 423 in the middle fossa, on the anterior cerebral surface of the petrous bone, into the Casserian ganglion. This ganglion is of a semilunar shape, and presents, on removing the dura mater, a dark and flat appearance, with its filaments mat- ted or having the plexiform arrangement. On raising this ganglion, the smaller motor or anterior root will be seen to pass on its under surface without any adhesion. It is easily separated and may be traced on to the inferior maxillary nerve, with which it unites. Three large branches proceed from this ganglion, the oph- thalmic, the superior, and the inferior maxillary nerves. The first enters the orbit through the foramen lacerum superius, and supplies the eye and its appendages with common feel- ing or general sensibility ; the second or superior maxillary is distributed to the upper jaw and face, supplying these parts also with sentient nerves ; the third or inferior maxil- lary nerve is the largest branch and passes through the fora- men ovale. Its motor portion supplies the muscles of mas- tication, as the temporal, masseter, pterygoid, and buccina- tor, while the sensitive goes to the lower jaw, tongue, chin, lips, &c. Sixth Prir, Motor es Externi or Abducentes Oculi, (Fig. 118.) This pair is of a size between the third and fourth. Each nerve arises from the superior extremity of the corpus pyra- midale, close to the pons, passes forward to the body of the sphenoid bone, where it penetrates the dura mater, courses the cavernous sinus on the outside of the carotid, enters the orbit through the foramen lacerum superius, and goes to the rectus externus muscle. The root of the nerve has been traced through the corpora pyramidalia into the gray matter of the olivary bodies. Seventh Pair, Portio Dura and Portio Mollis, (Figs. 16, 109.) — This pair is regarded by some as two distinct nerves, and so divided. The portio dura is the smaller of the two, and arises from the upper part of the medulla oblongata close to the lower part and side of the pons, below the crus cerebelli and in front of the corpus restiforme, into the gray neurine of which its fibres can be traced. It is called the facial 424 NERVES OF ENCEPHALON. nerve, and, according to Mr. Bell, lias its origin from the respiratory tract. It enters the foramen auditorium inter- num, passes along the aqueduct of Fallopius, and emerges at the stylo-mastoid foramen, from whence it is distributed to the muscles of expression. The portio mollis, or auditory nerve, is the larger of the two, and the most posterior. It arises from the side of the calamus scriptorius, the floor of the fourth ventricle, and the corpus restiforme,})y several filaments which form a very soft, white cord ; then unites with the portio dura, and enters along with it, the internal auditory foramen, from which, at the hase of this canal, it separates and goes to supply the internal ear, as the cochlea, semicircular canals, &c. This nerve is the nerve of hearing. The Eighth Pair consists of the Glosso Pliaryngeal, (Figs. 91, 118,) Pneumogastric, or par vagum, and the Spinal accessory. The glosso pharyngeal arises, by four or six filaments, from the fissure between the olivary and restiform bodies, or from the respiratory tract; these unite into a small nerve which joins the par vagum. The par vagum, or pneu- mogastric, arises below the last, in the same groove between the corpus olivare and corpus restiforme, by ten or fifteen filaments, which, uniting together, form a larger nerve than the glosso-pharyngeal ; the two now proceed together to the foramen lacerum posterius, where they are joined by the third portion — the spinal accessory. This latter nerve arises low in the neck — as low as the fourth or fifth verte- bra, and occasionally as low as the seventh cervical, by several filaments from the respiratory tract on the sides of the medulla spinalis, between the roots of the anterior and posterior spinal nerves ; it ascends behind the liga- mentum denticulatum, receiving filaments from the spinal nerves, in its ascent, and after entering the foramen inag- nus, proceeds to the foramen lacerum posterius, where it joins the other portions of the eighth pair. They all pass through the foramen lacerum posterius, anterior to the jugular vein, and then each proceeds to its peculiar BLOOD-VESSELS OP THE BRAIN. 425 place of distribution — the glosso pharyngeal to the tongue and pharynx, the pneumogastric to the lungs and stomach, and the spinal accessory to the muscles on the side of the neck. The several portions of the eighth pair, at the foramen lacerum posterius, have each a distinct sheath of dura ma- ter; though the par vagum and spinal accessory, having heen seen occupying the same canal, have been compared to a spinal nerve, the latter representing the anterior or motor root, the former the posterior or sentient. Ninth Pair, Lingual or Hypoglossal, (Figs. 118, 9 1.) — These belong to the tongue, and are motor nerves. They arise by a number of filaments, which vary from four to ten, from between the corpus pyramidaleand olivare. These filaments unite into a single trunk, one for each side, and receiving a sheath of the dura mater, pass through the anterior con- dyloid foramen of the occipital bone, to be distributed prin- cipally to the tongue. BLOOD-VESSELS OF THE BRAIN. The internal carotid and vertebral arteries are the great sources of supply of blood to the brain. Each internal caro- tid gets into the cavity of the cranium, by a tortuous course through the carotid canal of the temporal bone. On leav- ing this canal it ascends through the cavernous sinus, and at the anterior clinoid process it gives off the ophthalmic artery which goes to the eye and its appendages. At this point the carotid gives off, in its course, small branches to the cavernous sinus and dura mater. The remainder of its branches supply the brain, and consist of the anterior, middle, and posterior cerebral. The anterior branch, anterior cerebri, called also the artery of the corpus callosum, proceeds forward and inward, and after uniting with its fellow by a transverse branch, (the anterior communicating artery ,) ascends upon the upper sur- face of the corpus callosum, supplying this body and the inner surface of the hemispheres. The middle artery is the largest, and goes outward to the fissure of Sylvius, supplying the anterior and middle lobes of the cerebrum, and accend- 426 BLOOD-VESSELS OF THE BRAIN. ing upon the upper surface of the hemispheres to anasto- mose with the anterior and posterior cerehral arteries. The posterior branch passes hackward to join the posterior cere- bral artery, forming the side of the circle of Willis, and is called the posterior communicating artery. FIG. 119. The internal carotid sometimes sends off a hranch called the ar- teria 'choroidea, which passes into the mid- dle cornu of the lat- eral ventricle, and is distributed upon the plexus choroides. The vertebral arte- ries arise from the sub- clavian, sometimes from the aorta. They ascend in a straight line through the series of foramina in the transverse processes of the six upper cervical vertebrae, anterior to the cervical nerves. At the second vertebra these arteries take a direction outward, and then again ascend vertically through the foramen in the transverse process of the atlas. After this they take a horizontal direction backward, round the superior oblique process of the atlas in a depression at its back part, and then ascend upward and inward through the foramen magnum, into the cranium, penetrating the dura mater a FIG. 119 represents the Circle of Willis, surrounding the Sella Turcica. 1 Vertebral arteries. 2 The two anterior spinal branches, forming a single trunk. 3 Posterior spinal artery. 4 Posterior meningeal. 5 Inferior cere- bellar. 6 Basilar artery. 7 Superior cerebellar artery. 8 Posterior cere- bral. 9 Posterior communicating branch of internal carotid. 10 Internal carotid. 11 Ophthalmic artery. 12 Middle and cerebral artery. 13 Anterior cerebral arteries. 14 Anterior communicating artery. BLOOD-VESSEIS OF THE BRAIN. 427 little above the condyles of the occipital bone. In the cranium they are seen on the under surface of the medulla oblongata, approaching each other till they reach the pos- terior part of the pons. At this point they unite into a common trunk called the basilar artery. The vertebral arteries in their course send off small ar- teries to the membranes of the spinal marrow and adjacent muscles, and at their superior extremity they give off three important branches, the anterior and posterior spinal, and inferior cerebellar arteries. The anterior and posterior spinal, as elsewhere stated, are two long and delicate branches, the one in front, the other behind the spinal cord, running the entire length of this organ and giving off branches to the several spinal nerves. The basilar artery, formed by the junction of the two vertebrals, is situated on the median line of the pons, send- ing many fine branches into its substance, and at its upper edge giving off four branches, two to each side, the superior cerebellar and posterior cerebral arteries. The former wind round the crura cerebri, send a branch with the seventh pair of nerves into the internal auditory foramen and finally distribute themselves upon the upper surface of the cerebellum, anastomosing with the inferior cerebellar arte- ries. The posterior cerebral are much larger branches, and separated from the latter at their origin by the third pair of nerves. They receive the posterior communicating branch of the carotids, wind round the crura cerebri, to which branches are supplied, and are finally spent upon the pos- terior lobes, anastomosing with the middle and anterior arteries of the cerebrum. The circle of Willis will now be understood to be formed in front and laterally by the internal carotids and their posterior communicating branches, while the back part of the circle comes from the basilar. This circle surrounds the commissure of the optic nerve. The veins of the brain have already been noticed with the sinuses of the dura mater. 428 BLOOD-VESSELS OF THE HEAD. SECTION IV. % BLOOD-VESSELS OF THE HEAD IN THEIR NUMERICAL ORDER. The external and internal carotid, and vertebral arteries, are the great sources which supply the head with blood. FIG. 120. The external and in- ternal carotids arise from the common carotids in the neck, opposite to the space between the os-hy- oides and the thyroid cartilage. The external carotid ascends from this origin to the neck of the lower jaw,adjacent to the meatus auditorius exter- nus. It is crossed near its origin by the lingual nerve; also by the di- gastric and stylo-hyoid muscles, and is covered in front by the platysma, and superficial fascia. Its upper extremity is imbedded in the substance of the parotid gland. It gives off the following branches : SUPERIOR THYROID. LINGUAL. Hyoid. Dorsalis linguae. Sublingual. Ranine, which is the continued trunk of lingual. FACIAL. Inferior palatine. Submaxillary. Sub-mental. Inferior labial. Inferior coronary. Superior coronary. FIG. 120 represents the branches of the External Corotid Artery, a Arte- ria-innominata. 6 Common carotid, c Bifurcation of common carotid, d External carotid, e Internal carotid artery. / Superior thyroid, g- Lingual. h i Facial, j Submental. fc Continuation of facial. I m Inferior and supe- rior coronary arteries, n Nasal or angular branch, o External carotid con- tinued, p Internal maxillary, q Temporal, r Posterior auricular, s Occip- ital arjery. BLOOD-VESSELS OP THE HEAD. 429 INTERNAL MAXILLARY, (Fig. 121.) Tympanic branch. Greater or middle meningeal. Less meningeal. Inferior dental, or maxillary. Posterior deep temporal. Masseteric* Pterygoid. Buccal. Anterior deep temporal. Superior dental, or alveolar. Inferior orbitar. Superior palatine. Superior pharyngeal. Spheno-palatine. Lateralis nasi. Angularis, or terminating branch. INFERIOR OR ASCENDING PHARYNGEAL. Pharyngeal branches. Posterior meningeal. OCCIPITAL. Inferior meningeal. Princeps cervicis. POSTERIOR AURICULAR. Stylo-mastoid. TEMPORAL. Anterior auricular. Transverse facial. Middle temporal. Anterior temporal. Posterior temporal. The superior thyroid is the first branch of the external carotid, and descends to be distributed principally to the FIG. 121. thyroid gland. As it is con- nected with the neck, we defer any further notice of it till that part of the body comes under examination. The lingual artery arises just above the latter, and passes inward above the os-hyoides to the base of the tongue. It is covered at its origin by the digastric and stylo-liyoid muscles, and at the base of the tongue lies between the hyo-glossi and genio-hyo-glossi, whence it runs forward to the tip. FIG. 121 represents the branches of the Internal Maxillary Artery. 1 Ex- ternal carotid. 2 Trunk of transverse facial. 3 4 Terminal branches of external carotid. 3 The temporal. 4 Internal maxillary artery— the first part of its course extending to the first arrow. 5 Pterygoid, or second part of its course between the two arrows. 6 Pterygo maxillary, or terminating por- tion. The branches belonging to these three divisions are, 7 A tympanic branch. 8 Greater meningeal. 9 Lesser meningeal. 10 Inferior dental. Th second division are muscular branches, as the temporal, masseteric, pterygoid and buccal. 11 Superior dental. 12 Infra orbital. 13 Posterior palatine. 14 Spheno palatine, or nasal. 15 Pterygo palatine. 16 Pterygoid, or Vidian. 430 BLOOD-VESSELS OF THE HEAD. The liyoid is the first branch and supplies the parts above the os-hyoides. The dorsalis linguce, the second branch, ascends to the dorsum of the tongue supplying the base of this organ, the fauces and the velum. The sublingual is the third branch, and sends branches to the sublingual gland, the inylo-hyoid muscle, and the mucous membrane ; this sometimes comes from the facial. The canine forms the continued trunk of the lingual, and advances forward between the genio hyo-glossus and lin- gualisj to the tip of the tongue, sending oif branches on either side as it proceeds forward. The facial artery arises a few lines above the lingual, opposite the os-hyoides, ascends behind the digastric mus- cle to the base of the lower-jaw, a little anterior to its angle, above and closely connected with the sub-maxillary gland. It mounts over the lower jaw anterior to the masseter mus- cle, then ascends to the angle of the mouth, and still upward to the angle of the eye, where it terminates by anastomosing with the ophthalmic branch of the internal carotid. Its branches are : The inferior palatine which ascends by the side of the pharynx, between the stylo-glossus and stylo-pharyngeus muscles, to supply the tonsils and velum, and anastomoses with the superior palatine from the internal maxillary. The submaxillary sends off several branches to the sub- maxillary and adjacent lymphatic glands. The sub-mental comes oif at the base of the lower jaw and proceeds forward upon the mylo-hyoid muscle, above the anterior belly of the digastric to the chin, supplying these muscles and anastomosing with its fellow of the opposite side, and with the inferior dental and inferior labial arte- ries. The next branch is the inferior labial, given off after the facial has made its curve upon the face. This supplies the muscles and integuments of the lower lip. At the angle of the mouth is the inferior coronary. This sometimes supplies the place of the inferior labial. BLOOD-VESSELS OF THE HEAD. 431 A little higher is the superior coronary. Both these course along the margins of the lips, close to the mucous membrane, sending many branches to the substance of the lips, and forming by anastomosis with their fellows of the opposite sides, a complete circle round the mouth. The lateralis nasi is the next in order, supplying the side and dorsum of the nose ; while the angularis is the termi- nating branch of the facial, anastomosing with the nasal branches of the ophthalmic. This artery in its ascent is connected by anastomosis with the lingual, the inferior dental as it escapes from the anterior mental foramen, the transverse facial and inferior orbitar arteries. The inferior or ascending pliaryngeal artery is one of the smallest branches of the external carotid, and varies in its origin. It mostly arises opposite to the lingual, sometimes higher up, and occasionally springs from one of the other branches. It ascends on the side of the pharynx, covered by the stylo-pharyngeus, to the base of the skull, where it divides into its two principal branches, the pliaryngeal sup- plying the pharynx, tonsils, palate, and Eustachian tube, and the posterior meningeal passing through the foramen lacerum posterius, and distributed upon the dura mater at the base of the brain. The occipital artery arises opposite the facial, proceeds backward behind the digastric, the sterno-mastoid, and trachelo-mastoid muscles along the groove within the mas- toid process, and then ascends upon the occiput between the complexus and splenius muscles, anastomosing with its fellow, the posterior auricular, and the temporal arteries. Its principal branches are muscular, supplying the mus- cles just mentioned ; the inferior meningeal, which ascends through the foramen lacerum posterius, to the dura mater, and the princeps cervicis, which is a large branch and may be regarded as the continued trunk of the occipital. It de- scends to the deep muscles of the neck, and anastomoses with the profunda cervicis of the subclavian, thus preserv- ing the circulation, when the common carotid is ligated. Posterior auricular artery is a small branch, and arises a 432 BLOOD-VESSELS OF THE HEAD. little above the occipital, not Tinfrequently in common with it ; it ascends behind the parotid gland, between the mas- toid process and the meatus auditorius, supplying the in- teguments of the posterior ear and scalp. Some of the branches are seen to pass through the pinna to the anterior surface of the ear. Its only branch having a name, is the stylo-mastoid. This enters the stylo-mastoid foramen, and distributes branches upon the aqueduct of Fallopius and the tympanum. The temporal artery (Fig. 120) is one of the terminating branches of the external carotid. It ascends through the substance of the parotid gland, over the root of the zygoma, in front of the meatus auditorius, about an inch and a half above the zygomatic arch, where it terminates by dividing into an anterior and posterior branch. Its branches are the anterior auricular to the anterior part of the pinna. The transverse facial passes horizontally upon the face below the duct of Steno, crossing the masseter muscle to be distributed to the adjacent muscles and integuments, and anastomosing with the facial and infra-orbitar arteries. This artery often arises from the external carotid. The middle temporal passes through the temporal fascia and supplies the temporal muscle. The anterior temporal, one of the terminating branches, goes forward to the os-frontis, supplying the muscles and integuments in this region and anastomosing with its fellow of the opposite side, and with the supra orbital arteries. The posterior temporal, the other terminating branch, proceeds backward and upward, anas-' tomosing with the posterior auricular and occipital arteries. The internal maxillary artery (Fig. 121) is the remaining terminal branch of the external carotid. It is the great artery supplying the mouth and the whole of the dental apparatus. Dissection. — Saw the zygomatic arch through at both ends, and turn it down with the masseter muscle ; divide the tendon of the temporal muscle from its insertion into the coronoid process ; divide the rarnus about its cen- tre and disarticulate. Eemove the jaw with the external BLOOD-VESSELS OP THE HEAD. 433 pterygoid muscle, when this artery, with the deep branches of the inferior maxillary nerve, will be exposed. This artery commences in the substance of the parotid gland, opposite the meatus auditorius externus ; passes horizontally inward behind the neck of the lower jaw, between it and the internal lateral ligament, and between the inferior dental and gustatory nerves, to the space be- tween the pterygoid muscles ; at this point it passes either between these muscles, or winds over the pterygoideus externus, describing a tortuous course forward, inward, and somewhat upward to the tuberosity of the superior maxil- lary bone, upon which it makes a considerable curve, and then dips down into the pterygo-maxillary fossa, where it terminates. Its branches are as follow : A tympanic branch, which passes through the glenoid fissure to the tympanum, and also supplies the temporo- maxillary articulation. The greater meningeal} or middle artery of the dura mater, coming off behind the neck of the lower jaw, ascends to the foramen spinale of the sphenoid bone, through which it passes into the cranium, and there divides into an anterior and a posterior branch, which diverge and occupy the grooves on the internal surface of the parietal and temporal bones, supplying the dura mater and the anterior cranial bones. The lesser meningeal passes through the foramen ovale to the dura mater, and is often a branch of the greater. The inferior dental or maxillary, as has already been described, arises opposite the greater me- ningeal behind the neck, and descends between the bone and internal lateral ligament to the posterior dental foramen, which it enters along with the inferior dental nerve; it then follows the course of the canal beneath the roots of the teetYij into &at\ of which it sends successively a small branch, till, arriving opposite the bicuspid, it divides into two branches, one of which comes out at the anterior men- tal foramen to supply the chin, and anastomose with the facial ; while the other is the continued trunk going for- ward as far as the symphysis, and supplying the canine and incisor teeth. 28 434 BLOOD-VESSELS OF THE HEAD. The posterior deep temporal arises next in order; it is con- cealed by the external pterygoid and temporal muscle, and is distributed to this latter muscle. The pterygoid arteries come next ; they vary ip number and size, and, as their name implies, supply the pterygoid muscles. The masseteric and the buccal go to the masseter and buccinator muscles, and also give branches to the lining membrane of the mouth. The buccal sometimes comes from the superior dental, or the next branch in order. The anterior deep temporal, which comes off just before the internal maxillary, enters the pterygo-maxillary fossa, and ascends to be distributed upon the temporal muscle, anastomosing with the posterior and middle deep temporal. The superior dental or alveolar comes off next, and has been stated, in noticing the vessels supplying the teeth, to wind round the tuberosity of the superior maxillary bone, sending branches through the posterior dental canals, to the molar teeth, and to the lining membrane of the an- trum ; it then proceeds forward along the alveoli, supply- ing them and the gums. The inferior orbital arises at the upper part of the pterygo maxillary fossa, and after sending a few branches into the orbit, through the spheno-maxillary fissure, it enters the infra orbitar canal, in company with the infra orbitar nerve, and on arriving near the anterior orifice of this canal, it sends downward a branch to supply the incisor and canine teeth, and lining membrane of the antrum. It finally emerges at the infra orbitar foramen, anasto- mosing with the ophthalmic and facial arteries. The superior palatine also comes off in the pterygo-max- illary fossa, and descends to the posterior palatine canal, distributing branches to the soft palate; it then curves forward, in a groove, upon the hard palate, internal to the alveoli, giving off ramifications to the lining membrane of the roof of the mouth, and proceeds to the foramen iu- cisivum, to anastomose with the spheno-palatine or nasal artery. BLOOD-VESSELS OF THE HEAD. 435 The superior pharyngeal, m ptery go-palatine, is sometimes a branch of the latter, and supplies the upper part of the pharynx and Eustachian tube. The spheno-palatine, or nasal, is the terminating trunk of the internal maxillary, and passes along with the nerve of the same name, through the spheno-palatine foramen, into the nose, where it divides into two branches — one going to the septum, the other to the middle and lower turbinated bones, and their mucous membrane. BRANCHES OF INTERNAL CAROTID ARTERY. (Fig. 119.) Tympanic branch. Anterior meningeal. Ophthalmic — its branches, Lachrymal. Central artery of the retina. Supra-orbital. Short ciliary. Long ciliary. Muscular. Posterior ethmoidal. Anterior ethmoidal. Palpebral. Nasal. Frontal. Anterior cerebral. Middle cerebral. Posterior communicating. Choroidean. BRANCHES OF TERTEBRAL ARTERY. Posterior spinal. Anterior spinal. Inferior cerebellar. Basilar — formed by junction of two vertebral. Its branches are, Superior cerebellar. Posterior cerebral. All these vessels have been described under the respect- ive heads of Blood-vessels of the Brain and Eye, which see. The veins, corresponding to the branches of the external carotid, have both a similar course and name, so that a repetition would be unnecessary here. SECTION IV. TABLE OF MUSCLES OF THE HEAD. According to the arrangement of Mr. Harrison, these muscles are classed in accordance with the part upon which they chiefly act. Six classes are made, embracing thirty- six pair, and two single muscles. FIRST CLASS — one muscle, The muscle of the Scalp, or Occipito- Frontalis. SECOND CLASS — eleven muscles, Those of the Ear, which are arranged iuto three groups. 436 MUSCLES OF THE HEAD. First Group — three muscles : Superior auris, or Attollens aurem. Anterior auris, or Attrahens aurem. Posterior auris, or Retrahens aurem. Second Group— Jive muscles : Tragicus. Antitragicus. Helicis major. Helicis minor. Transversalis auris. Third Group — three muscles : Stapedius. Tensor tympani. Laxator tympani. THIRD CLASS — eleven muscles, Those of the Eye and Appendages, are arranged in two groups — one of which acts on the appendages, the other on the ball of the eye. First Group— five muscles r Occipito-Frontalis — its palpebral in- sertion. Corrugator supercilii. Levator palpebrse superioris. Orbicularis palpebrarum. Tensor tarsi. Second Group — six muscles : Rectus superior, or Levator oculi. Rectus inferior, or Depressor oculi. Rectus internus, or Adductor oculi. Rectus externus, or Abductor oculi. Obliquus superior. Obliquus inferior. FOURTH CLASS— /our muscles, Those of the Nose, arranged in two groups : First Group — proper to the Nose: Pyramidalis nasi. Compressor nasi. Second Group — common to the Nose and upper Lip : Levator labii superioris alseque nasi. Depressor labii superioris alseque nasi. FIFTH CLASS — ten muscles, Those of the Mouth, arranged in four groups : First Group — one muscle : Orbicularis oris. Second Group — two muscles common to the upper Lip and Nose : Levator labii superioris alaeque nasi. Depressor labii superioris alseque nasi. Third Group — two muscles : Levator labii inferioris. Depressor labii inferioris. Fourth Group— Jive muscles : Levator anguli oris. Depressor anguli oris. Zygomaticus major. Zygomaticus minor. Buccinator. SIXTH CLASS — muscles of mastication, Which act on the lower jaw, and are four pair : Masseter. .Temporal. Pterygoideus externus. Pterygoideus internus. RELATIONS OP THE MOUTH WITH THE HEAD. 43 T CHAPTER VI. ANATOMICAL AND PHYSIOLOGICAL RELATIONS OF THE MOUTH WITH THE DIFFERENT PARTS OF THE HEAD. THE mouth, from the detailed description already given, it will be perceived, is a very complex apparatus, com- prising organs of the greatest variety, in form, size, deli- cacy and adaptation, and embodying functions equally various and useful, as seen in the multitude of duties they perform, their surprising promptitude and harmony of action, and their universal sympathy and relation with all the various parts composing the head ; and we may add the rest of the body likewise, as we shall have to show in the proper place. So close and so essential is this mutual relation of the mouth and head, that they cannot exist separately. It is only necessary here to make a very general enu- meration of these relations with the mouth, so as to impress especially upon the dental student their magnitude and importance. The mouth, it will be recollected, consists of the anatomi- cal elements of bone, muscle, blood-vessel, nerve, gland, cellu- lar, mucous and adipose structure; which, variously combined, constitute the upper and lower jaw, the teeth, the gums, the tongue, the palate, the tonsils, the cheeks, &c., in a word, all the parts forming the walls of the cavity of the mouth, as well as the various organs contained within it. Now each one of these elements, and of the several organs they form, has a relation more or less direct and intimate with the other portions of the head. The upper jaw-bone is connected to a number of the bones of the cranium and face, thereby forming one continuous whole, containing numerous cavities of various sizes and uses, as the cavity of the cranium for lodging the brain ; the orbital and nasal cavities, the maxillary sinus, &c. The loiverjaw, by its articulation with the temporal bones, pre- sents a fulcrum and lever, which, in connection with the 438 RELATIONS OF THE MOUTH WITH THE HEAD. various muscles attached to it and the head, is in its power, strength, beauty and mechanical contrivance, incomparably superior to any thing in human mechanics. The teeth have not only a direct connection with the jaws, but by means of their blood-vessels and nerves, they have nearly as direct and close a relation with the brain and its membranes, the eye, the ear, and the nose. The fifth pair of nerves come from the brain and send branches to the teeth, jaws, eyes, nose, ears, &c., endowing the whole with sensibility to pain, and so close is this sympathy manifested between the teeth and brain, that the simple act of teething frequently occa- sions the most frightful convulsions ; while cases are not wanting to show that irritation of this same set of nerves, from decayed teeth, has been the cause of tic-douloureux, ul- ceration of the eye, photophobia, blindness, and the most excruciating pain of the ear. The internal maxillary artery is the principal vessel establishing the vascular relationship between the mouth and brain, and other parts of the head and face. In congestion, apoplexy, and delirium, the condition of the circulation in the brain is reported by an almost similar state of the circulation in the mouth. The gums, tongue, palate, tonsils, &c., by the same kind of anatomical rela- tionship of blood-vessels and nerves, display each their several sympathies with the other portions of the head. We now pass to the second division, the physiological rela- tions of the mouth with the different parts of the head. The functions of the mouth have been stated to be those of prehension, mastication, insalivation, suction, deglutition, and speech ; functions lying at the very foundations of life and connecting man with the outer world. The first series of these functions comprises the commen- cing stages of digestion, which comprehend the preparatory but essential elements in that grand and fundamental pro- cess of nutrition, which not only builds up the head in all its different parts, and supplies its daily and unceasing waste, but further preserves, with an ever vigilant and un- tiring care, all its various relations with the mouth, and RELATIONS OP THE MOUTH WITH THE HEAD. 439 extends its influence throughout the whole and every part of the body. The last mentioned function of the mouth, speech, is more closely related with the brain, though it has the same or- gans for its performance, as those employed in the above functions of the first stages of digestion. For this function is impaired when the teeth are lost, the palate cleft, the tonsils swollen, or the lip cleft, and it is partially or entirely lost in congestion and apoplexy of the brain. PABTTHIRD, THE LANGUAGE OF ANATOMY, II. THE TRUNK PART THIRD. CHAPTEK I. THE TRUNK. PASSIVE ORGANS OF THE TRUNK. THE BONES. Division. — 1. Spine. 2. Thorax. 3. Pelvis. SECTION I. THE SPINE OR VERTEBRA. The spine, so called from its posterior projecting processes resembling thorns, is situated on the posterior median line of the trunk, and is composed of a column of bones, called vertebral, placed one above the other in a regular series from top to bottom, and designated the vertebral column. The vertebrae are divided into true and. false. The twenty- four movable bones are the true ; the sacrum and coccyx, which assist in forming the pelvis, the false. The true and false vertebrae form an upright rod or column, having four curvatures, one in the neck, concave behind and convex in front ; a second in the back, concave in front and convex behind ; a third in the loins, concave behind and convex in front, and a fourth in the pelvis, concave in front and con- vex behind. This arrangement is found to add greatly to the strength of the spine, and results from the difference in the thickness of the bodies of the several vertebrae, as well as of the intervening fibro cartilage. The true vertebras are divided into cervical, dorsal, and lumbar, as they are found in the neck, the back, or the loins. The length of the true spine is estimated as a general rule at twenty-four inches; six inches being 444 SPINAL COLUMN. FIG. 122. allowed to the cervical and lumbar portions severally, and twelve to the back, which is equal to the other two together. Common characters of a vertebra, Fig. 123. — Each vertebra consists of a body and processes. The body is the anterior, thick, and middle por- tion, of a cylindrical form and sym- metrical. Its surfaces above and below are flattened, convex in front and concave behind. Its anterior and posterior surfaces present nu- merous foramina for the passage of the vessels. The processes are nine in number, two lateral, four oblique, two trans- verse, and one spinous, which are situated upon the back and lateral parts of the body. The lateral, one on each side, are seen to arise by a pedicle from the posterior part of the body. They proceed backward in the form of an arch, expanding in their course, forming the lateral boundaries of the spinal canal, and uniting posteriorly in the spinous process. At the body these processes are grooved superiorly and inferi- orly into a notch, which, being ap- plied to a corresponding notch in the adjacent vertebra, is converted into a foramen called the interver- Fi«. 122 represents a side view of the Spinal Column, with its curvatures and internal spongy structure, a Atlas, b Dentata. c Seventh cer- ^ I vical vertebra, d Twelfth dorsal vertebra, t Fifth lumbar. / First bone of the sacrum, g Last bone of sacrum, h Coccyx. i Spinous process, j j Intervertebral foramina. SPIXAL COLUMN. 445 tebral foramen, for the FlG- 123' passage of the spinal nerves. The spinous process, formed by the junction of the two lateral, is situated on the posterior median line, and consti- tutes the most project- ing part of the vertebra. The series of these pro- cesses,, one above the other, presents a long and prominent crest be- hind, known as the spine. The use of these processes is to give attachment to tendons and muscles. The transverse project outward from the lat- eral, nearly at right angles, and also give attachment to muscles, and in the back sustain the ribs. The oblique or articular processes are two on each side — one superior, the other inferior. They arise, in common with the transverse, from the lateral. Their surfaces are smooth, covered with cartilage, and articulated with simi- lar processes upon the adjacent vertebrae above and below. The body and processes thus arranged bound a foramen, which, running through the whole series of vertebral bones, constitutes the spinal canal, for lodging the spinal marrow. The structure of the body (Fig. 123) is extremely light and spongy, consisting almost entirely of the cellular or cancellated tissue of bone. The processes are much more compact in their structure. The development of a vertebra takes place generally by three points of ossification, one for the body and one for each side. In addition to these prin- cipal, there are five other accessory points, one for the FIG. 123 represents a Lumbar Vertebra — its upper surface. 1 Spinous pro- cess. 2 Same process connecting with the lateral lamina. 3 Superior artic- ular process. 4 Transverse process. 5 Inferior articular process. 6 7 Body of the vertebra. 9 Foramen for spinal marrow. 446 CERVICAL VERTEBRA. spinous, two for the transverse, and one for the upper and lower surfaces of the body. The three primary centres present their ossific points about the seventh or eighth week, those of the lateral por- tions being observed a little in advance of the body, and at birth the three pieces are found separate. In the first year union begins with the lateral portions and at their poste- rior part, where they come together to form the spinous process, and during the third and fifth year with the body. The osseous nuclei for the extremities of the spinous and transverse processes, are seen about the fifteenth or six- teenth year, and their union is not completed till the twenty-fifth or thirtieth year. CERVICAL VERTEBRAE — COMMON CHARACTERISTICS. A FIG. 124. B Thecervical vertebras occupy the superior portion of the column, are seven in number, and are the smallest in size. The superior sur- face of each is concave from side to side_, and bounded by a vertical ridge; the lower surface is concave from before backward, and has a ridge at the anterior edge. The lateral processes are narrow and long, and bound a large and triangular canal. The spinous process is bifid, short and horizontal. The transverse is short and perforated at its basb by a foramen for the passage of the vertebral vessels. Its upper surface is grooved for the cervical nerves. FIG. 124, A represents the upper surface of a Cervical Vertebra. 1 Spinous process bifurcated. 2 Lateral lamina. 3 Superior articular process. 4 Pos- terior surface of body. 5 Transverse process bifurcated. 6 Anterior surface of body. 7 Extremity of superior articular process. 8 Vertebral foramen for spinal marrow. FIG. 124, B represents the lower surface of the same vertebra. 1 Spinous process bifurcated. 3 Posterior root and notch of transverse process. 5 Bi- furcation of transverse process, and the process showing a foramen in it for giving passage to the vertebral artery. 6 Body of vertebra. 7 Inferior artic- ular process. 4 Foramen for the spinal marrow. • CERVICAL VERTEBRA 44 T The oblique articular processes are oval, the two superior being directed upward and backward, and the two inferior downward and forward ; the surfaces of the superior are rather convex, those of the inferior concave. CERVICAL VERTEBRA — INDIVIDUAL CHARACTERISTICS. The atlas , or first cervical vertebra, so called from sup- porting the head, differs from the rest in having no body nor spinous process, and consisting simply of a bony ring. A tubercle marks this ring on its anterior portion ; behind, on the same part, the A FIG. 125. B surface is concave, smooth, and oval, for articulating with the tooth-like process of the axis or second vertebra. The upper and lower edges of this ring are for the attachment of ligaments. The posterior arch is long, slender, and presents a tubercle instead of a spine, upon the upper surface of which, near the oblique processes, is a groove for the vertebral artery, in making its curve, to enter the brain. It also receives the sub-occipital or first cervical nerve. The spinal foramen is very large, and divided by the transverse ligament into two ; the anterior and smaller receives the odontoid process, the posterior and larger contains the spinal cord. The intervertebral notches are behind instead of being in front of the oblique processes, as in all the other vertebras. The superior oblique pro- cesses are horizontal, concave, and their smooth surfaces look from before, backward and outward ; they articu- late with the condyles of the occipital bone, and are admi- rably adapted to the nodding motion of the head. The FIG. 125, A represents the upper surface of the Atlas. 1 Tubercle in place of spinous process. 2 Posterior part of ring of atlas. 3 Where the transverse ligament is attached. 4 Superior articular process. 5 Groove leading to vertebral foramen. 6 Transverse process. 7 Articular surface for odontoid process. 8 Anterior margin of ring of atlas. 9 Foramen for spinal marrow. FIG. 125, B represents the lower surface of Atlas. 1 Tubercle in place of spinous process. 23456789 Correspond to similar points, as in Fig. 125, A. 448 CERVICAL VERTEBB^E. inferior are circular, nearly flat, and suited to the rotatory motion. The transverse processes are noted for their great length — projecting much beyond those below, and have the foramen at their base for the passage of the vertebral artery. The axis, or second cervical vertebra, is also called the dentata from its tooth-like or odontoid process, which is the FIG. 126. peculiar characteristic of this vertebra. This process arises from the central part of the superior surface of the body, and ascends vertically. It presents some- what the form of a tooth — hence its name. Its anterior surface is smooth, /£ ~ and articulates with the anterior arch of the atlas. Its posterior is also smooth, and has the trans- verse ligament in connection with it. Its apex is pointed for the attachment of the vertical ligament, and upon each side, from a rough surface, originate the moderator or FIG. 127. check ligaments. This process is the pivot round which turns the atlas. The spinous process is long, large, and forked. The spinal foramen is heart- shaped. The superior oblique processes are seen, on each side of the odontoid, on a plane anterior to those below, and are smooth, circular, and nearly hori- zontal. The inferior look forward and downward, and are flat. The transverse processes are short and not bifid — the body of this vertebra is large. The cervical ver- tebras increase gradually in size to the seventh, (Fig. 12*7.) The seventh cervical is called vertebra prominens , from its FIG. 126 represents the Dentata or second bone of the Vertebrae, a Body. 6 Odontoid process, c Articular face for atlas, d Foramen for vertebral artery, e Spinous process. / Inferior oblique process, g Superior oblique process. FIG. 127 represents the seventh cervical vertebra, seen from below. 1 Spinous process. 2 Vertebral foramen. 3 Articular process. 4 Lateral lamina. 5 Foramen for vertebral artery and vein. 6 Germ of the accessory rib. 7 Supernumerary rib at its styloid. 8 Body. DORSAL VERTEBRA. 449 long spinous process, which projects beyond all the rest and is readily felt beneath the skin, ends in a tubercle and is not bifurcated, and gives attachment to the liga- mentum nuchae. Its transverse processes have no foramina, or if there be any, they are small and transmit only a vein. PECULIARITIES OF DEVELOPMENT IN THE CERVICAL VERTEBRA. The atlas, instead of the usual three primary ossific cen- tres, is seen to have four and sometime's five ; one for each lateral portion, one, occasionally two, for the anterior arch, and one for the centre of the posterior arch. The lateral centres unite with the posterior centre during the second and third years, and with the anterior about the fifth or sixth year. The axis is found with five centres of ossifica- tion, two for the odontoid process, one, sometimes two, for the body, and one for each lateral part. The body and odontoid process begin ossifying about the sixth month, and are found united about the third or fourth year. The lat- eral portions unite soon after birth, and join the body about the fourth or fifth year. The seventh cervical vertebra is found to have the anterior portion of its transverse process frequently presenting a separate osseous centre about the second or sixth month, which unites with the body about the fifth or sixth year. Separate ossific centres have also been noticed in the trans- verse processes of the second, fifth and sixth cervical verte- bra?, and also the first lumbar. DORSAL VERTEBRAE — COMMON CHARACTERISTICS. (Fig. 128.) The dorsal vertebras occupy an intermediate position be- tween the cervical and lumbar, and are also intermediate in size; they become less and less from the first to the third or fourth, and then increase to the last. The body is thicker behind than before, and more cylindroid than those of the neck ; the upper and lower surfaces at the posterior edge, near the origin of the lateral processes, present two small articular facets for receiving one half of the head of each rib — the adjoining vertebra having a corresponding de- 29 450 LUMBAR VERTEBRA. A F 128 B pression for the other half. The lateral processes are "broad. The spinous are trian- gular, long, ending in a tuber- cle and bending downward so as to overlap each other. The oblique processes are vertical — the superior facing directly backward — the inferior as di- rectly forward. The spinal foramen is round and large. The transverse processes are directed backward, are large and long, and have their front surfaces at the extremities smooth, for articulation with the tubercle of the ribs. This is true of all except the last two; they have no articulating surfaces. The intervertebral foramina for the nerves are large. DORSAL VERTEBRA — INDIVIDUAL CHARACTERISTICS. The first and the last two dorsal present individual pecu- liarities. The first has a full articulating surface on each side, and receives the whole head of the first rib, and also has at its inferior edge a half articular surface for the half head of the second rib. The flatness of the body and its projecting spinous process resembles it to the cervical. The three lower dorsal approximate in their appearance to those of the loins. They have full depressions in the middle and sides, for their corresponding ribs, and the last two have no articular surfaces on their transverse processes. The tenth dorsal has occasionally on its transverse process the articular face. LUMBAR VERTEBRAE — COMMON CHARACTERISTICS. (Fig. 129.) The lumbar vertebrae are five in number; occupy the lower part of the column, and are much the largest in size FIG. 128, A represents a dorsal vertebra seen from above. 1 Spinous pro- cess. 2 Transverse process. 3 Articular facet for the articulation of the rib. 4 5 Articular process and notch. 6 7 Body. 8 Foramen for spinal marrow. FIG. 128, B represents a side view of the same vertebra. 1 Body. 2 Ar- ticular face for head of the rib. 3 Superior articular process. 4 5 Transverse process and articular face. 6 Spinous process. 7 Inferior articular process. 8 Notch, intervertebral. PELVIC VERTEBRA. 451 of all the true vertebrse. The bodies are deeper FIG. 129. before than behind, and broad transversely. The superior and inferior surfaces are flat and oval, having projecting and hard edges. The intervertebral notches are very large, especial- ly the lower — the spinal foramen is triangular or oval, and larger than in the dorsal. The spinous pro- cess is broad, thick, and short, ending in a rough border. The oblique processes are vertical— the superior being con- cave and looking inward — the inferior convex and looking outward and forward. The transverse are long, slender, and stand at right angles. The fifth or last lumbar vertebra is somewhat peculiar in having its body of greater size, deeper generally in front than behind, so as to give some- thing of the wedge shape ; in its transverse processes being thick, short, and round, and in the spinal foramen being larger. The false or pelvic vertebrce consist of the sacrum and coccyx. The sacrum is situated at the lower part of the true ver- tebrae, occupying the posterior and superior portion of the pelvis. Its form is triangular, and its position is like that of a wedge, its base being above, and apex below — having the innominata laterally — the lumbar vertebra upon its superior, and the coccyx on its inferior portion. This bone, in the adult consisting of one piece, in the child forms five pieces. Its surfaces are the anterior, posterior, and two lateral. The anterior surface is concave from above downward, and marked by four transverse lines, showing the original divisions of the bone into five pieces. At the outer extrem- ity of these lines four foramina are observed, called the anterior sacral foramina, for transmitting the anterior sa- cral nerves. The two superior of these foramina are quite large — the rest diminish in size as they descend ; they are FIG. 129 represents the upper surface of a lumbar vertebra. 1 Spinous pro- cess. 2 Lateral lamina. 3 Superior articular process. 4 Transverse process. 6 7 Body. 8 Vertebral foramen. 452 PELVIC VERTEBRAE. all smooth, funnel-shaped, and have their orifices looking outward. The anterior projecting edge of the upper l><>m' of the sacrum is called its promontory. The posterior surface is rough and convex ; on its middle line four promi- nences are observed cor- responding to spinous processes, which are not unfrequently seen united into a single ridge or crest. The fourth and fifth spines are generally deficient, leaving a triangular space which is simply closed by ligaments, and in place of the spine, presenting, on either side, two tubercles styled comua, which unite with similar cornua from the coccyx, forming foramina for the passage of the last sacral nerve. On either side of the spinous processes four foramina are seen, smaller than those in front, transmitting the pos- terior sacral nerves. External to these foramina, a row of five tubercles is noticed, though indistinct, corresponding to the transverse processes of the true vertebrae ; and internal to these foramina, between them and the spinous processes, another row of indistinct tubercles is seen, regarded as analogous to the oblique processes. The lateral or iliac surfaces are rough, irregular, and triangular, having their superior portions broad and cov- ered with cartilage to articulate with the ilium. Their inferior surfaces are thin, and give attachment to the greater and lesser sacro-ischiatic ligaments. Fio. 130, A represents a front view of the Sacrum. 1 Superior articular process. 2 Superior surface of first sacral vertebra. 3 Lateral side of sa- crum. 4 Anterior surface of the bodies of the sacral vertebra. 5 Grooves leading to the anterior sacral foramina. 16 Apex of last sacral vertebra. Fio. 130, B represents a side view of the Sacrum. 1 Superior articular process. 2 Sacro vertebral angle. 3 Hollow of the sacrum. 4 Termination of sacral canal. 5 Articular surface for coccyx. 888 Spinous processes, or crest. PELVIC VERTEBRAE. 453 / On the upper surface, in the centre, is an oval articula- ting surface for uniting with the last lumbar vertebra. On each side of this is seen a broad triangular expansion, upon which rests the psoas magnus muscle, and lumbo-sacral nerve. The anterior edge of this expansion is continuous with the linea ileo-pectinea. Between this expansion and the oblique process is a groove for the fifth lumbar nerve. The lower extremity of the sacrum is truncated and pre- sents a small oval surface for articulation with the coccyx. The structure of the sacrum is mostly spongy and cancel- lated, thick, yet very light, and covered by a thin compact layer. Its development occurs usually from twenty-one points of ossification ; five for each of the three superior divisions, one for the body, one for each lamina, and one for each lateral portion. The two lower divisions have each three points, one for the body and one for each lateral por- tion. As many, however, as thirty-four and thirty-five points of ossification have been observed. Ossification is observed to commence in the bodies of the three upper sa- cral vertebras, about the eighth or ninth week, a little later than that of' the true vertebrae, in the two lower about the fifth month, and in the lateral portions from the sixth to the ninth month. The union of these latter with the body is found to take place from below upward, and in the fol- lowing order : the fifth piece about the second year, and the first not before the fifth or sixth year. The epiphyses are developed about the fifteenth or eighteenth year, and the sacrum is completely fused into one piece by the thirtieth year. It is articulated above with the last lumbar vertebrae, below with the coccyx, and laterally with the two ossa innominata. Coccyx — (xoxxvf , cuckoo, from likeness to a cuckoo's beak,) is situated at the lower extremity of the sacrum, and cor- responds to the tail of the inferior animals, (Fig. 131.) It consists of four caudal vertebrae, sometimes only three, which in the old are often consolidated into two or a single piece. Its shape is triangular, the base above, broad and 454 LIGAMENTS OF THE SPINE. articulating with the sacrum. Upon each side of the base at Fio 131 ^s posterior part, a small process or cornu arises to unite with a similar one upon the sacrum, forming a foramen for the passage of the fifth sacral nerve. The three lower pieces diminish in size to the last, and in old age, as already stated, become firmly fused together and also with the sacrum, presenting one solid piece. The anterior or pelvic surface of the coccyx is smooth, concave, and marked by three transverse lines, denoting its original separation into four pieces. This surface supports the rectum. The posterior surface is rough, presenting ridges and tubercles to which ligaments and muscles are attached. The coccyx is light and spongy. Its development is from four points, one to each piece. Ossification in the coccyx is noticed soon after birth in the first piece, from five to ten years in the second ; from ten to fifteen in the third ; and from fifteen to twenty in the fourth piece ; the several pieces unite in pairs — the first in order are the two first pieces, then the third and fourth, and lastly the second and third; and between forty and sixty years the coccyx becomes united with the sacrum. Its union with the sacrum by fusion, is much earlier in the male than in the female. LIGAMENTS OP THE SPINE — COMMON ARTICULATIONS OF THE VERTEBRAL COLUMN. 1. The anterior vertebral ligament, (Fig. 132,) as its name implies, is situated on the front surface of the spinal column, extending from the axis to the sacrum, and consists of fibres which are broad and strong, increasing in breadth as they descend, and adhering more strongly to the intervertebral matter, than to the bodies themselves. The fasciculi of this ligament vary in length and thickness. The super- ficial fibres are long and run to several vertebras. The FIG. 131 represents a front view of the Coccyx. 1 Upper articular surface for last lumbar vertebra. 2 Cornu of coccyx. 3 Transverse process. 444 Margin of the four bones. LIGAMENTS OF THE SPINE. 455 deep ones are short and ex- FIG. 132. tend simply to adjoining ver- tebrae. It is thin in the neck, thicker in the back, and again becomes thin in the loins. The use of this ligament is to bind together the several ver- tebrae, and prevent over-ex- tension of the spine. 2. The posterior vertebral ligament (Fig. 133) is situated upon the back part of the bodies of the spinal column, within the canal, and extends from the axis to the FIG. 133. sacrum, the fibres being traced still higher to the cuneiform process of the os-occipitis, and lower to the coccyx. This ligament has its fibres arranged in a similar manner to the anterior, consisting of short and long. It is broad over the intervertebral substance, to which it is also more adherent. It is loose upon the bodies, being separated by the veins which escape from the large foramina seen on this surface. This liga- ment antagonizes the former by opposing excessive flexion of the spine, while, at the same time, it assists in binding together and strengthening the several vertebrae. 3. Intervertebral ligaments are situated between the bodies of each vertebra, except the first and second. Their struc- ture is of a mixed character, partaking both of ligament and cartilage, hence called also fbro-cartilages. They are so strongly united to the upper and lower surfaces of the vertebrae, that it requires even maceration for a complete separation. FIG. 132 represents the Anterior Vertebral Ligament. 1 Anterior vertebral ligament. 2 Anterior costo-vertebral ligament. 3 Internal transverse liga- ment. 4 Inter-articular ligament. FIG. 133 represents the Posterior Vertebral Ligament, a a Intervertebral •ubstance. 6 6 Surfaces of bony bridges where cut. c Posterior vertebral ligament, d Opening for a vertebral vein. 456 LIGAMENTS OF THE SPINE. Their thickness varies in different parts. In the neck and loins the thickness is greater before than behind — while in the back it is less. The curves of the spine are due, in great measure, to this substance. A transverse Section of this ligament shows its fibres to run in a concen- tric form, being very close and compact near the surface, and as they approach the centre, spaces or interstices are left, containing a soft, pulpy, semi-fluid substance, while in the centre, the spaces become still wider and more cellu- lar, and present still more of the pulpy matter. This cen- tral pulpy and conical body is a movable, elastic fulcrum, upon which the different vertebrae turn. It is more abun- dant, softer, whiter, and more transparent, in proportion, in infancy, than in any after period. In old age it diminishes both in quantity and elasticity, which accounts, in some measure, for the stiffness of the spine in old people. The use of the intervertebral ligaments is manifold. They, in common with those just described, tie the several vertebrae together ; they help to form the spinal canal, give sockets to the heads of the ribs, allow the flexibility of which the spine is capable ; and, by their elasticity, pre- serve the spine of its uniform height : they also lessen the effects of shocks from concussion. 4. Ligamenta subflava, or yellow ligaments, (Fig. 134.) These ligaments close the spinal canal behind, and are FIG. 134. situated between the posterior arches of the different vertebra?. They are found between all the vertebrae from the axis to the sa- crum. They are in pairs, on each side of the median line, and are twenty-three in number. They ex- tend from the inferior margin of the lamina above, to the superior margin of the corresponding one below. Their structure consists of yellow elastic tissue. Fig. 134 represents the Yellow Ligaments (ligamenta flava.) a a One pair of the yellow ligaments. 6 Capsular ligament of the one^ side. ARTICULATIONS OP THE VERTEBRA. 45 1 dense, very strong, and having the fibres vertical. They oppose flexion, and by their elasticity restore the spine to its erect condition. 5. The Supra-spinous ligament is found at the extremity of the spinous processes, from the last cervical vertebra to the sacrum. In the neck it is continued on to the occipital bone, under the title of ligamentum nuclice. It separates the muscles on either side of the median line, and is the rudi- mentary structure of this very powerful ligament in the lower animals. 6. The Inter-spinous ligaments are situated between the gpinous process of the dorsal and lumbar regions, above and below, and not between those of the neck. They are thin in the back, and thicker and stronger in the loins, and have the multifidus spinge muscles attached to them. T. The Inter-transverse ligaments are situated between the transverse processes of the lower dorsal and lumbar vertebrae, not being distinct either in the cervical or upper dorsal. They consist of thin fibrous membranes. 8. Articulation of the oblique processes. — These processes have an irregular capsule, consisting of ligamentous fibres not fully developed, extending from one bone to the other. Their articular surfaces are covered with cartilage, and connected by synovia! membranes. PECULIAR ARTICULATIONS OF THE VERTEBRAL COLUMN. 1. Articulation of the atlas with the occiput. — The condyles of the occipital bone, and the oblique processes of the atlas, are the bony portions especially concerned in the joint. There is the usual cartilage and synovial membrane at this joint; and also a ligamentous capsule, or capsular ligament on each side, which is attached to the circumference of the condyles and the margin of the glenoid cavity of the atlas. This capsule consists of thin and loose fibres which are, however, strong at the anterior and external parts. Anterior ligaments, (anterior occipito-atloid.) — These are two in number, one a strong, round cord, situated on the median line, and extending from the basilar process to 458 ARTICULATIONS OF THE VERTEBRA. the anterior tubercle of the atlas ; the second, deeper than this, is broad and membranous, and extends from the ante- A FIG. 135. B rior margin of the foramen magnum, to the anterior arch of the atlas. These ligaments are covered in front by the anterior recti muscles, and behind are in relation with the dura mater. The posterior occipito-atlantal ligament is attached above to the occipital foramen, and below to the posterior arch of the atlas. It is composed of a broad, thin and weak membrane, closely adheres to the dura mater, gives passage to the ver- tebral arteries and sub-occipital nerves, and is covered by the posterior recti and oblique muscles. The lateral ligaments, one on each side, extend from the transverse process of the atlas, to the transverse process of the occiput, they consist of strong fasciculi of fibres, which expand and are continuous with the sheath surrounding the carotid vessels and nerves at the base of the brain. 2. Articulation of the axis, or dentata, with the occiput. — The ligaments connecting the axis or second vertebra with the FIG. 135, A represents an anterior view of the Ligaments which connect the first and second vertebrae with the occiput, a Anterior occipito-atloid liga- ment, b Anterior annular ligament, c Where anterior vertebral ligament begins, d e Capsular ligament of oblique processes of atlas and dentata. / Joint between first and second cervical vertebrae, g- External fibres of anterior annular ligament. FIG. 135, B represents a posterior view of the ligaments which connect the first and second vertebra with i\m occiput, a Atlas, b Dentata. c Posterior occipito-atloid ligament, d d Capsular ligament of oblique processes of the atlas and occipital condyles. e Ligament between the first and second verte- brae. // Lateral fasciculi of this latter ligament, g First pair of the yellow ligaments, h Capsular ligament between the oblique processes of the second and third vertebrae. ARTICULATIONS OF THE VERTEBRA. 459 occiput, are three, the middle straight and two moderator ligaments. The middle straight ligament^ called occipito- axoid or apparatus ligamentosus colli, consists of a broad, thick hand of fibres which extend from the cuneiform pro- cess, forming the foramen magnum, to the summit of the odontoid process, and pass on behind this process to be at- tached to the superior central FIG. 136. portion of the transverse liga- ment of the atlas — and still lower down into the body of the second vertebra and into the bodies of the third* and fourth, where they are Continuous with the posterior common ligament. The moderator or oblique ligaments, (Fig. 136,) called also the lateral alar or check ligaments, extend from each side of the odontoid process obliquely, upward and outward, to be attached above to the inner edge of each condyle. Tnese ligaments are short, thick, and strong, and limit the extent of rotation. They have in front the anterior occipito-atlantal ligaments and some cellular tissue, and behind the middle straight ligament. 3. Articulation of the atlas with the axis or dentata. — The ligaments of this articulation are five, (Fig. 136.) The transverse, anterior and posterior atlanto-axoid, and two capsular. The transverse is situated behind the odontoid process, crossing the area of the atlas from the inner edge of the oblique process on the one side, to the same point on the opposite. It is a strong, thick, ligamentousband, concave, and smooth anteriorly, having a synovial membrane, and connected at this point with the odontoid process, forming a joint. At its centre, behind the process, some of its fibres ascend to join the middle straight ligament, and others FIG. 136 represents the ligaments which unite the atlas and dentata with the occiput. 1 Posterior vertebral ligament, its upper portion. 2 Transverse ligament. 3 4 Appendices of transverse ligament. 5 Moderator or check ligament. 6 7 Capsular ligaments. X. 460 THE THORAX. descend to be attached to the body of the axis, presenting, as seen, in the figure above, a crucial appearance. The use of this ligament is to retain the odontoid process and the atlas in secure connection with each other. The anterior atlanto-axoid ligament extends from the ante- rior tubercle and arch of the atlas to the base of the odon- toid process, and is continuous with the anterior vertebral ligament. It is strong and thick. The posterior atlanto-axoid is situated between the pos- terior arch of the atlas, and the lamina of the axis ; it corresponds to the ligamenta sub-flava, is a thin, broad, and weak membrane, but not elastic. The capsular ligaments are two in number, one on each side, and belong to the oblique processes of the atlas and axis. They surround the margins of these processes, and are loose enough to allow freedom of motion. They are, like all the oblique articulations, lined with synovial mem- brane, which occasionally communicates with the syno- vial membrane of the transverse ligaments and odontoid process. The ligaments of the false vertebree — the sacrum and coccyx, will be noticed along with those of the pelvis. SECTION II. THE THORAX OR CHEST. The chest forms the upper part of the trunk, and is com- posed of the sternum and costal cartilages in front — the ribs laterally, and the dorsal vertebrae, which have already been considered, behind. Its form is conoidal, flattened in front, rather concave behind, and convex upon the sides. Its summit or superior portion is smaller than the inferior or base, and presents a very oblique opening ; cordiform in its shape, and much lower in front than behind. The base is a large foramen, bounded by the lateral and posterior margins of the lower ribs and their cartilages, marking the situation of the diaphragm. The sternum (attpvov, the breast) is situated on the me- ' : THE STERNUM. 461 dian line at the front part of the thorax. Its direction IB obliquely downward and forward, its superior end being consequently nearer the spine than the inferior. Its upper portion is on a A FIG. 137. level with the third dorsal, and its lower with the elev- enth dorsal ver- tebra. Its ave- rage length is six inches. The sternum, in the adult, consists of three pieces — a supe- rior, middle, and inferior, which, in old age, are often fused into one. The superior lone is quadrilateral in shape, thick and broad above, narrow below, and concave transversely at its upper edge. The interclavicular liga- ment occupies this concavity, at either end of which, corre- sponding to the angles, are the articular cavities for the sternal ends of the clavicle. Just below this articulation is a depression on each side for the cartilage of the first rib, and still lower down, at the point of junction with the second piece, there is, on each side, a half fossa, which, with a similar one upon the second bone, receives the cartilage of the second rib. The middle lone is much longer than Fia. 137, A represents a front view of the Chest, a First bone of the ster- num. 6 Second bone of sternum, c Third bone of sternum, called ensiform cartilage, d First dorsal vertebra, e Twelfth dorsal vertebras. /First rib. g Head of first rib. h Neck, t Tubercle, j Seventh or last true rib. k k Cos- tal cartilages. I Floating ribs, m Groove for the intercostal artery. FIG. 137, B represents the Sternum, a First piece. 6 Second piece, c Third piece, or ensiform cartilage, d Articular face for clavicle, e Articu- lar surface for first rib. / Articular surface for second rib. g h i j Articular •urfaces for the last five true ribs. 462 THE STERNUM. the upper ; it is wide in the centre, and narrow at either end; its sides furnish cavities, complete for the third, fourth, fifth, and sixth ribs, and half cavities for the second and seventh ribs. These cavities approach nearer each other as they descend, so that the sixth and seventh are in contact. The inferior, or third bone, called ensiform, or xiphoid cartilage, being usually in the cartilaginous state in the adult, is the smallest of the three pieces. It is thin, and varies much as to form and size, being sometimes pointed, sometimes bifid, sometimes thick — looking forward, and then backward, and occasionally perforated with a central foramen. Its base is united to the lower extremity of the middle bone ; its sides have the transverse muscles of the abdomen attached to them, and its point is connected with the linea alba. The sternum, as a whole, has its anterior surface flat, or a little convex — is covered by the aponeurosis of the pecto- ral muscles — has the tendons of the sterno mastoid muscles attached to its superior portion, and is crossed by trans- verse lines, marking its original divisions into as many as six pieces. Its posterior surface is smooth, somewhat concave, and covered by a shining periosteum. It also presents trans- verse lines, though not so distinct as those in front. The structure of the sternum is spongy, covered by a thin com- pact layer. Its development is from a number of points varying from six to fourteen, which do not unite till late in life. The osseous centres for the first bone of the ster- num are one or two in number, and make their appearance during the fifth and sixth months — those of the second and third soon after — and the fourth at the close of foetal life or shortly after birth. Ossification of the ensiform cartilage varies from the second to the eighteenth year. The several pieces of the sternum commence uniting from below up- ward. The fourth and third are seen to join^ about puberty, the third and second between twenty and twenty-five, and the second and first between twenty-five and thirty years. THE RIBS. 463 The ensiform cartilage does not join the sternum till late in life, about forty or fifty years. It articulates with sixteen bones, the two clavicles and seven true ribs on each side. THE KIBS, (COSm) The ribs are twenty-four in number, twelve on each side, and are divided into the true and false. The true are seven in number, extend from the vertebra? to the sternum, and are called vertebro-sternal. The false extend from the ver- tebras to the ribs, and are called the vertebro-costal or aster- nal. The two last having their extremities free, are called FIG. 138. floating ribs, and are the shortest. The ribs present an arched form, and run ob- liquely down- ward and for- ward from the vertebrae towards the sternum. They increase successively in length from the first to the eighth, and then diminish to the last. The breadth diminishes gradually from the first to the twelfth. Common characters of the Eibs. — Each rib consists of two extremities, a vertebral and sternal, two surfaces, external and internal, and two margins, superior and inferior. The vertebral extremity or posterior end has a head, neck, and tubercle. The head is divided by a middle ridge into two articular faces, which are received into corresponding pits on two contiguous vertebrae, the edge between them sinking into the intervertebral substance. To the ridge the inter- articular ligament is attached. The neck is the contracted, round, and thick portion upon which the head rests. It is situated before the transverse process, to which it is attached f ,.«-, FIG. 138, A represents the upper surface, B the lower surface of a rib. « Head of rib. & Tubercle, c Anterior end for costal cartilage, d Groove for artery and nerve, e Angle of rib. \ 464 THE RIBS. by the middle costo-trans verse ligament. Its upper border has a ridge for the attachment of the anterior or internal cos to-transverse ligament. The tubercle is external to the neck, and seen on the posterior under surface of the rib, about an inch from the head. It consists of two portions, an internal and external. The former is smooth, and articu- lates with the transverse process, the latter gives attach- ment to the external costo-iransverse ligament. On the out- side of the tubercle the rib makes a turn which is called its angle. To this the tendon of the sacro lumbalis muscle is connected. This angle increases in distance from the tuber- cle, from the first rib downward to the last, where it is not so distinct. The anterior or sternal extremity is hollow for the reception of the cartilage. Beyond or external to the angle, is the body or shaft of the rib. Its external sur- face is convex and smooth, and gives attachment to various muscles. Its internal surface is concave and lined by the pleura. Its superior margin is smooth and round, and gives attachment to the intercostal muscles. The inferior is thin and sharp, and has its inner side grooved, to lodge the in- tercostal vessels and nerves, and for the attachment of the intercostal muscles. Characters peculiar to some of the ribs. — The first is the shortest — it is flat, strong and broad — has its surfaces pre- FIG. 139. senting upward and down- ward, instead of forward and backward, has no angle and is not twisted. Its head has but one articular sur- face, and is not divided. There is no groove on the inferior or rather posterior edge. On the central part of the upper surface there is a broad and shallow fossa for the subclavian artery. In front of this is a slight eminence for the scale nus anticus muscle. Fio. 139 represents the upper surface of the first Rib. a Head. 6 Tuber- cle, c Anterior surface, d Groove for subclavian artery. « Groove for subcla- vian vein. / Anterior extremity for cartilage, g Tubercle for scalenui anticus. CABTILAGES OP THE BIBS. 465 The second rib in some measure resembles the first in hav- ing little or no angle or twisting, and partly presenting upward. The tenth rib has but a single articular surface. The eleventh and twelfth have likewise but one articular face, have no neck, angle nor tuberosity, and are pointed at their extremity. The ribs are spongy, with a thin covering of compact matter. Their development is from three points of ossifica- tion— one for the body, one for the head, and one for the tuberosity. Ossification begins in the body of the rib sooner than in the vertebras. In the epiphysis it begins between the sixteenth and twentieth years ; and complete union of all the parts takes place about the twenty-fifth year. Each rib articulates by its head, with two contigu- ous vertebra3, except the first and the last, which articulate each with a single vertebra ; each unites also, by its ster- nal end, with the costal cartilage. Cartilages of the Ribs. — The costal cartilages are of the permanent class, and are regarded as part of the skeleton of the chest. They are situated at the anterior extremities of the ribs, the seven uppermost of which they connect with the sternum. The first is short — the rest increase successively in length, to the seventh ; and from this to the last they diminish, so that the twelfth has merely a tip of cartilage. The costal extremity of each cartilage is broader than the sternal. The depression in the end of the rib receives the former, while the cavities along the sides of the sternum, receive the latter. Their anterior surface is convex, and gives origin to the great pectoral muscle. The posterior is concave and lined partly by the pleura. Their margins, like the ribs, bound the intercostal spaces, and give attachment to the internal intercostals. The first cos- tal cartilage is short, broad, and descends obliquely down- ward in the direction of the first rib; the second and third are nearly horizontal; the rest ascend more and more. The three superior cartilages of the false ribs are blended the one with the other, and the two lower, as already stated, are free and floating. 30 466 LIGAMENTS OF THE CHEST. These cartilages are the longest in the body ; they are, in middle life, white, flexible, and extremely elastic. In old age they are much disposed to ossify, the costal being more subject to this change than the sternal end. When this occurs they become opaque, and assume a similar or- ganization with the ribs. The costal cartilages contain no vessels or nerves, but are covered by a vascular, fibrous membrane, called the perichondrium. LIGAMENTS OP THE CHEST. The ribs are articulated behind to the vertebrae, and in front to the sternum. The vertebral articulation takes place at two points of the posterior extremity of the rib, viz: at its head, and at the neck and transverse process. The head has the capsular and the inter-articular liga- ment, and two synovial membranes. The capsular, anterior, stellate, or radiating ligament (Fig. 132) arises from the front margin of the head of the rib, and radiates by three short bands of ligamentous fibres, the superior of which to the vertebra above — the middle to the intervertebral substance, and the inferior to the vertebra below. These bands are so connected as to form an imperfect capsule, hence one of the names of this ligament, capsular. The intervertebral ligament is attached to the ridge divi- ding the articular surfaces on the head of the rib, and goes to be inserted into the intervertebral substance. This lig- ament is short, strong, and somewhat yellow, and also separates the two synovial membranes which belong to the head of each rib, except the first, eleventh, and twelfth. Internal or anterior cos to-trans verse ligament, (Fig. 140.) This ligament arises narrow from the lower margin of the transverse process, and has a broad insertion upon the crest of the upper edge of the neck of the rib below. External costo-transverse or posterior ligament, (Fig. 140,) arises from the extremity of the transverse process, and pro- ceeds externally to be inserted into the non-articular portion of the tubercle of the rib. It is a short, flat plane of fibres. LIGAMENTS OF THE CHEST. 467 -The ligaments con- FIG. 141. The middle costo-transverse ligament is situated behind the neck of the rib, and between it and Flo< ^Q. the front part of the corresponding transverse process. It is a short, strong ligament, which can only be seen by separating the bones, or making a horizontal section of them. These ligaments firmly connect the ribs and vertebras together, and also allow the ribs the necessary freedom of motion in the upward, downward, and slightly forward and backward directions. The sternal articulation of the fiibs.- necting the costal cartilages with the ribs and sternum are the anterior and. posterior, the superior and inferior costo- sternal ligaments. The ster- nal ends of the ribs are hollow and receive the convex ends of the cartilages by a species of union somewhat resem- bling gomphosis. The anterior costo-sternal ligament arises from the costal cartilage and consists of a thin layer of ligamentous fibres which radiate over the front of the sternum and intermix with those of the opposite side, and with the fibres forming the tendon of the pectoralis major muscle. The posterior costo-sternal ligament has the same ra- diated arrangement of its fibres as the anterior, is smaller FIG. 140 represents the Ligaments at the vertebral end of the ribs, a a Lig- aments of the spinous processes. 6 6 b Yellow ligaments, c Anterior or internal costo-transverse ligament, d Posterior or external costo-transverse ligament. FIG. 141 represents the Ligaments about the Sternum and Ribs. 1 Capsular ligament of the sterno clavicular articulation. 2 Interclavicular ligament. 3 Rhomboid or costo clavicular ligament. 4 Interarticular cartilage, 5 An- terior costo sternal ligaments of the first and second ribs. 468 GENERAL REMARKS UPON THE CHEST. and situated on the posterior surface of the articula- tion. The superior and inferior costo-sternal ligaments are simply narrow fasciculi of fibres, connecting the upper and lower margins of the sternal end of the costal cartilages with the sides of the sternum. The cartilage of the first rib, it seems, has no synovial membrane, and is continuous with that of the sternum. The cartilage of the second rib, at its junction with the sternum, like the heads of the ribs, is divided by a liga- mentous partition, forming two cavities and two synovial membranes. The sixth, seventh, and eighth, and occasion- ally the fifth and ninth, have articulations with each other lined by a synovial membrane. External and internal liga- mentous fibres pass from one to the other. Ligamentous fibres are seen passing from the cartilage of the seventh rib near the sternum, and spreading themselves over the anterior surface of the xiphoid ligament, and are named costo-xiphoid ligaments. The motion of the ribs at the sternum is very limited. GENERAL REMARKS UPON THE CHEST. The Chest thus composed of the sternum, ribs, costal car- tilages, and dorsal vertebras, all bound together by the ligaments, presents a large and very important cavity for containing the lungs, the organs of respiration, and the heart, the chief agent of circulation. This cavity, which in the skeleton is continuous with the abdominal, in the fresh subject is separated from the latter by the diaphragm. When the arms are detached from the trunk it presents the form of a truncated cone, having the apex above and the base below, flattened before and behind, and convex at the sides. This form of the chest, however, may be materially altered by tight lacing, and by disease. The anterior wall is, as already stated, shorter and more oblique than the posterior, which is vertical. Its surface is rendered very irregular by grooves, processes, and angles. The intercostal spaces are wider in front than GENERAL REMARKS UPON THE CHEST. 469 behind. The superior opening of the chest presents ob- liquely downward and forward, and is oval, its lateral diameter being the greatest. It gives passage to th-3 trachea, oesophagus, vessels, nerves, muscles, cellular tis- sue, &c. The base of this cavity is represented by the dia- phragm, the circumference of which is bounded by the xiphoid cartilage, the inferior margin of the cartilages of the false ribs, and the lower dorsal vertebrae. The dimensions of the thoracic cavity vary according to age and in different individuals, and in the same individual according to the state of the diaphragm, whether ascending, descending, or quiescent. The capacity of the chest is intermediate between that of the abdominal and cranial cavity. Its diameters are three, the antero-posterior, trans- verse, and vertical. The antero-posterior has the greatest length below, and is shorter at either end than on the middle line, in consequence of the projection forward of the bodies of the vertebrae. The transverse is longest across the eighth ribs. The vertical has the greatest length of the three, and is longer at the sides than the middle, in conse- quence of the descent of the diaphragm. During inspiration all these, diameters are increased and the capacity of the chest enlarged in every direction, by the elevation of the ribs and the fall of the diaphragm. In expiration, on the contrary, these diameters are all less- ened by the falling of the ribs and the ascent of the dia- phragm, and the expulsion of air from the chest. In the foatus these motions do not, of course, take place, and the form of the chest is very different from that of the adult. The thoracic cavity is short, its sides compressed, and its base very broad, in consequence of the collapsed state of the lungs, and the great size of the liver. The antero-posterior diameter is large, to provide for the heart and thymus gland, while on the sides it is compara- tively small, on account of the unexpanded condition of the lungs. The vertical diameter is less, the ribs are closer together, and the intercostal spaces shorter. So soon, how- ever, as respiration begins, the chest expands, and all the peculiarities just mentioned are lost. 470 THE PELVIS. SECTION III. THE PELVIS. The pelvis is situated at the lower portion of the trunk, and is composed of four bones — the sacrum, coccyx, and two ossa innominata. The two former have been examined along with the spine. It only remains, therefore, to speak of the latter. Os-innominatum. — This bone is situated at the lateral and anterior portions of the pelvis, and in the adult is A FIG. 142. B composed of a sin- gle piece ; but in the young subject consists of three : the ilium, iscliium, and pubis. The ilium is sit- uated at the su- perior and outer portion of the pel- vis, and is the largest of the three bones composing the innominatum. This bone is com- monly called the hip, or haunch bone. It is somewhat triangu- lar, broad and flat. It is divided into a body, ala, and. pro- cesses. The body is the lower narrow portion, forming the upper and outer part of the acetabulum. It has, anteriorly, a FIG. 142, A represents an exterior view of the Os-innominatum. 1 Crest of Ilium. 2 Anterior superior spinous process. 4 Anterior inferior spi- nous process. 5 Notch for the psoas-magnus, and iliacus internus. 6 Ileo- pubic spine. 8 Obturator foramen. 9 Angle of pubis. 11 Descending ramus of pubis. 12 Tuberosity of ischium. 13 Lesser sciatic notch. 14 Spine of the ischium. 15 16 Greater sciatic notch. 17 Posterior inferior spinous pro- cesses of ilium. 18 Rough surface. 19 Posterior superior spinous process. 21 Dorsum of the ilium. FIG. 142, B represents an inner view of the innominatum. The figures 2 4 8 9 11 12 13 14 16 correspond to similar points as in Fig. A. 3 Groove for obturator vessels and nerves. 20 Posterior superior spinous process. 23 Posterior inferior spinous process. 22 Fissure between posterior processes. 21 Venter of ilium. 24 Svmphysis pubis. THE PELVIS. 471 rough, triangular surface, for articulating with the pubis ; and inferiorly and posteriorly, another for articulating with the ischium. The ala is the broad portion which expands upward and outward from the body; it has two surfaces and a circum- ference. Its external surface is rough, and irregularly con- vex and concave, and is called the dorsum. This surface has two semicircular lines — a superior and inferior. The superior is long, usually well marked, begins a short dis- tance behind the anterior superior spinous process, and takes a curved direction backward to the posterior part of the great sciatic notch. To this line, and all that part of the dorsum above, and between it and the upper edge of the ilium, with the exception of a small posterior portion, the gluteus medim muscle is attached. This excepted pos- terior part gives attachment to the gluteus maximus. The inferior line, a short distance above the acetabulum, curves backward from the anterior inferior spinous process to the fore part of the sciatic notch. To this line, and to the space between it and the superior line, the gluteus minimus muscle is attached. Below the inferior line, the body be- comes prominent, and gives attachment to a part of the gluteus minimus — the external tendon of the rectus/emorts muscle, and a portion of the capsular ligament. The internal surface of the ilium, called the venter, has its central and superior part very concave for lodging the iliacus internus muscle ; there is also seen upon it an ob- lique canal for the nutritious artery. Below the venter there is a rounded edge which is continuous with one from the promontory of the sacrum behind, and the pubis before, called the linea-ileo pectinea. All the surface above thia line enters into the false pelvis. The small surface below it, and above the sciatic notch, helps to form the true pelvis. The posterior part of this internal surface, is rough, and divided into two portions : the anterior, covered with car- tilage, and articulating with the sacrum; and the posterior, rough for the attachment of the sacro sciatic-ligaments. 472 THE PELVIS. The processes of the ilium are seen upon its circumference. Its superior border is called the crest In the young sub- ject this is an epiphysis, and presents the form of an italic 8, looking inward in front, and outward behind. The anterior extremity of the crest presents a projection called the anterior superior spinous process, which gives origin to the sartorius and tensor vaginw femoris muscles, and Pou- part's ligament. The posterior extremity of the crest is the posterior supe- rior spinous process, to which the sciatic ligaments are attached. The crest also has an inner margin, from which arises the trans versalis abdominis muscle, an outer margin for the attachment of the external oblique, and an interme- diate space for the internal oblique. The anterior circum- ference of the ilium presents a notch bounded above by the anterior superior spine, and below by the anterior inferior spine. This latter is above the outer part of the acetabulum and gives origin to the rectus femoris muscle. The notch has the gluteus medius attached to it, and an external cu- taneous nerve occupying it. Below and internal to the an- terior inferior spinous process, is a hollow, along which pass fhepsoas magnus and iliacus internus muscles; internal to this hollow and where the ilium unites with the pubis, is a prominence called the ilio-pectineal eminence. The poste- rior circumference, in addition to the posterior superior spinous process, has about an inch and a quarter below the posterior inferior spinous process. Below this spine the ilium becomes notched to form the sciatic notch. The ischium (Fig. 142) is the next in size of the bones of the innominatum, and is situated at the lateral and inferior part of the pelvis. It is the bone on which we sit. It con- sists of a body and processes. The body presents a trian- gular or pyramidal form, and has three surfaces, an inter- nal, posterior, and external. The internal surface, called the plane of the ischium, is smooth, broad above and narrow below. The posterior forms a prominent rounded surface, corresponding to the posterior parietes of the acetabulum. The external surface is much excavated and forms the lower THE PELVIS. 473 and outer part of the acetabulum. At this point the body contracts and presents a groove bounded above by the coty- loid ridge, along which the tendon of the obturator externus muscle passes. At the posterior part of the neck, just below the sciatic notch, is seen the spinous process which projects inward and backward, and to which is attached the superior gemellus muscle and the lesser sciatic ligament. Below this spine is a smooth pulley-like surface, round which turns the tendon of the obturator internus. As we descend, the next process is rough and large, and called the tuberosity — it is covered with cartilage, and presents three faces, one an- terior, which gives origin to the semi-membranosus muscle; and two posterior, from which the semitendinosus and bi- ceps arise. To the outer margin, the adductor magnus, quadratus femoris , and gemellus inferior are attached ; to the inner, the long sacro-sciatic ligament. Between the spine and the tuberosity is the lesser sciatic notch, converted into a foramen by the long sciatic ligament. From the tuber- osity the ramus ascends forward and inward to unite with the pubis, and bounds the inferior and internal portion of the thyroid foramen. It is a flat process, its surfaces pre- senting, externally and internally. Its anterior border bounds, in part, the lower outlet of the pelvis. The os-pubis (Fig. 142) is smaller than either the ilium or ischium, and is situated at the front part of the pelvis ; it consists also of a body and processes. The most external portion is regarded as the body; it is thick, and forms the internal and upper part of the acetabulum. Its lower por- tion unites with the body of the ischium ; its upper joins the ilium in the ilio-pectineal eminence. Its inner surface is smooth, and enters into the formation of the anterior pelvic wall. From the body proceeds, transversely inward and forward, a process called the horizontal ramus. The superior surface of this ramus is smooth, and bounded in- ternally by a process or tuberosity, called the spine of the pubis, which gives insertion to Poupart's ligament. From this spine proceed outward two ridges; the posterior is the more elevated and frequently sharp, called the crista} THE PELVIS. and forms the anterior portion of the linea ilio-pectinea, to which is attached G-imbernat's ligament and the fascia lata. The anterior ridge is more round, and ends at the upper margin of the acetabulum. Between the two ridges is situated the pectineus muscle. Internal to the spine of the pubis is the crest, leading transversely to the median line, and about an inch in length. It gives attachment to the rectus abdominis and pyramidalis muscles, and to the united tendons of the internal oblique and trans versalis. From the crest there is an inferior or descending portion called the sympJiysis and descending ramus. The symphysis is vertical and rough, and forms with the crest the angle of the pubis. It meets its fellow of the opposite side by an in- termediate substance of fibre-cartilage. The ramus goes backward and outward to meet the ramus of the ischium, and its outer edge bounds the thyroid foramen, while its inner edge gives attachment to the crus of the penis or the clitoris. The space between the rami on either side and below the symphysis describes a curve called the arch of the pubis. The innominatum, composed of three bones, presents at their common point of junction a deep, hemispherical cavity, the acetabulum or cotyloid cavity. The ilium forms a little less than two-fifths, the ischium a little more than two- fifths, and the pubis about one-fifth of this cavity. It is bounded by a deep notch internally, which is converted, by a ligament stretched across from the pubis to the ischium, into a foramen, through which pass the articular vessels. The superior and outer part of this cavity is smooth, cov- ered with cartilage, and receives the head of the thigh bone. The central portion and the part leading from it to the notch, is rough, gives attachment to the ligamentum teres, and contains a quantity of soft adipose matter. In the front of the innominatum and to the inside of each acetabulum are seen two large foramina, called the obturator or thyroid. These are formed by the ischium and pubis. The edge of this opening is thin and has superiorly a groove for the passage of the obturator vessels and nerve. LIGAMENTS OF THE PELVIS. 475 The rest of the opening is filled "by the obturator liga- ment. The structure of the innominatum is cellular internally, with a compact layer externally. Its development is from three principal centres of ossifica- tion, one for the ilium, one for the ischium, and one for the puhis, all of which meet in the acetabulum ; and five addi- tional or secondary points are noticed, one for the crest of the ilium, one for the tuherosity of the ischium, one for the anterior and inferior spine of the ilium, one for the angle of the pubis, and one for the centre of the acetabulum. These latter points appear at the twelfth year. Ossifica- tion is noticed first in the ilium, at the same time or soon after it occurs in the vertebrae ; about the third month in the ischium, and between the fourth and fifth months in the pubis, about the sixth year the rami of the ischium and pubis are found nearly ossified, and join in the tenth year. The three bones are complete in the acetabulum by the twenty-fifth year. The osinnominatum articulates with its fellow, the sacrum and the head of the femur. LIGAMENTS OF THE PELVIS. The mode of articulation Iretween the last lumbar verte- bra and the sacrum, is the same as those of the other ver- tebrae already described; by the inter vertebral, anterior and posterior, capsular, yellow, supra spinous, and interspinous ligaments, and synovial membranes. There is however an additional ligament, consisting of a short, thick, strong fas- ciculus extending from the transverse process of the last lumbar vertebra to the posterior superior part of the base of the sacrum, called lumbo-sacral ligament. The next liga- ment connecting the vertebral column to the pelvis is the ilio-lumbar. It arises from the transverse processes of the two lower lumbar vertebrae, and is inserted into the poste- rior crest of the ilium and into its posterior superior spinous process. The ligaments of the pelvis are those connecting the sacrum and ilium, those connecting the sacrum, coc- 476 LIGAMENTS OF THE PELVIS. cyx, and ischium, those binding the ossa-pubis together, and those uniting the sacrum and coccyx. FIG. 143. The sacro-iliac articulation consists of anterior and poste- rior sacro-iliac ligaments. The anterior sacro iliac liga- ment is a thin sheet of fibres passing from the ilium to the sacrum on the anterior surface of the joint. The posterio sacro-iliac liga- ment is much stronger than the anterior, and forms the chief bond of union between the sacrum and ilium. It consists of numerous strong ligament- ous fasciculi extending transversely and obliquely from the rough surface of the sacrum to the rough surface of the ilium, and to its posterior superior spine. This latter attachment receives the name of sacro-spinous ligament. The articular surfaces of the sacrum and ilium are co- vered with cartilage, and have an imperfect synovial mem- brane, more readily distinguished in the young than in the adult, and occasionally lubricated with fluid. Sacro-iscliiac articulation. The sacrum and coccyx are united to the ischium by two ligaments, the anterior and posterior s aero-sciatic. The anterior or lesser sacro-sciatic ligament arises broad and thin from the side of the sacrum and coccyx, crosses the other, and has a narrow insertion into the spine of the ischium. Its pelvic portion is connected with the coccygeus muscle. The posterior or great sacro-sciatic ligament is much larger, FIG. 143 represents a front view of the Ligaments of the Pelvis. 1 Ante- rior vertebral ligament, its lower end. 2 Sacro-vertebral ligament. 3 Ileo- lumbar ligament. 4 Sacro-iliac ligament, its anterior portion. 5 Obturator ligament. 6 Poupart's ligament. 7 Gimbernat's ligament. 8 Capsular liga- ment of hip-joint. 9 Accessory ligament of hip-joint. LIGAMENTS OF THE PELVIS. 477 longer and thicker than the anterior, and arises from the posterior inferior spinous process of the ilium, and the side of the sacrum and coccyx. It is inserted hy a broad attachment into the inner margin of the tuberosity of the ischium, which is traced forward in the shape of a falci- form process, upon the ramus of the is- chium, and serves to shield the internal pudic vessels and nerves. Posteriorly, it is covered by the glutens maximus muscle, to some of the fibres of which it gives origin. These ligaments are of use in forming the lower and lateral parietes of the true pelvis. By their crossing they convert the ischiatic notches into foramina, the larger and superior giving passage to the pyriform muscle, the gluteal and sciatic vessels and nerves, while the smaller and inferior transmit the internal pudic vessels and nerve, and the tendon of the obturator internus muscle. Articulation of the ossa pubis. — The two ossa pubis are united, along the median line, by an intermediate fibro-car- tilage. Its fibres assume the form of concentric laminaa, some of which are continued all round, while others are interrupted ; some take the oblique course, and cross each other. This articulation resembles, in some degree, the intervertebral, and sometimes contains, in its centre, a FIG. 144 represents a posterior view of the Ligaments of the Pelvis. 1 Base of sacrum. 2 Coccyx. 3 3 Crest of ilium. 4 4 Tuber ischii. 5 5 Greater sciatic notch. 6 Lesser sciatic notch. 7 Femur. 8 8 Sacro-iliac ligaments, posterior portion. 9 Sacro-spinous. 10 Posterior-sacro-coccygeal ligament. ]1 Obturator ligament. 12 Obturator foramen. 13 13 Upper attachment of the greater sacro-sciatic ligament. 14 Its lower attachment. 15 16 The two attachments of the lesser sciatic ligament. 478 GENERAL REMARKS UPON THE PELVIS. pulpy or viscid fluid. At its posterior portion, a delicate synovial membrane has occasionally been seen. The anterior pubic ligament consists of fibres passing in front of the symphysis, from the one side to the other. The posterior pubic ligament is made up of a few fibres on the posterior surface of the symphysis. The sub-pubic, or inter-pubic ligament, is situated beneath the symphysis to which it is connected. Its form is trian- gular, about half an inch broad, and consists of a strong, compact layer of fibres, passing from the crus of the pubis, on the one side, to a similar point on the opposite, round- ing off the angle or arch of the pubis. The triangular ligament of the urethra is below this sub-pubic ligament. The superior pubic ligament consists of a plane of fibres uniting the angles of the pubis. The obturator ligament closes the obturator foramen, and consists of a thin fibrous membrane, which is attached all round to the edge of this opening, except at its superior part, where the obturator vessels and nerve pass. Its outer and inner surfaces respectively give attachment to the ex- ternal and internal obturator muscles. The articulation of the sacrum and coccyx has been described under the ligaments of the spine. GENERAL REMARKS UPON THE PELVIS, AS A WHOLE. The pelvis, as we have seen, consists of the two ossa in- nominata, the sacrum and coccyx. These are divided on the interior by the linea ilio-pectinea, into the false and the true pelvis. All above this line, as high as the top of the ilium, is the false pelvis; all below is the true, and this line of separation between the two is called the superior strait. The cavity of the pelvis presents the form of a flat truncated cone, the base above, the apex below. It contains some of the viscera of the abdomen, while it and its parietes receive and support the organs of generation, and part of the uri- nary organs, at the same time furnishing attachment for many muscles. The upper or false pelvis is the base of this cone. In the GENERAL REMARKS UPON THE PELVIS. 479 dry skeleton it is deficient in front, but in the fresh subject it is closed in by the abdominal muscles. The alas of the ilia constitute its lateral and superior boundaries. The lower or true pelvis is a perfect bony canal, deeper however, at the sides and behind, than in front; the sacrum and coccyx forming its posterior wall, the ischia and part of the ilia its sides, and the pubis completing it in front. The true pelvis has two orifices, an upper and lower, called the superior and inferior straits, or outlets of the pelvis. The superior strait looks forward and upward, and its axis may be represented by a line drawn from the point of the coccyx to about an inch below the umbilicus. The inferior strait or lower outlet is smaller than the upper, and in the fresh subject is much smaller still, owing to the closing of the sciatic notches, which limits the opening to the space between the arch and rami of the pubis and the coccyx. The opening of the lower strait looks downward and for- ward, and its axis is marked by a line passing through its centre and striking the lower part of the first bone of the sacrum ; so that it will be seen that the perpendiculars to the planes of the two straits have different directions, and decussate or cross each other about the centre of the pelvis, forming an obtuse angle looking forward. The axis of the pelvis describes a curve, the upper strait looking down- ward and backward, the lower strait downward and for- ward, important practical points to recollect in parturition and in the operation for stone. DIFFERENCES BETWEEN THE MALE AND FEMALE PELVIS. The female pelvis differs from the male in several points. It is larger, the ala3 of the ilia are wider apart, more ex- panded and not so concave ; the depth of the pelvis is not so great. The upper and lower straits are both wider and rounder ; the sacrum is shorter, more concave, and wider ; the promontory of the sacrum is less ; the rami of the pubis are farther apart, but not so long as in the male ; and the arch of the pubis is regularly rounded and smooth, whereas in the male it forms an acute angle. The cartilage at the 480 GENERAL REMARKS UPON THE PELVIS. symphysis pubis is thicker in the female, the tuberosities are further apart, and the acetabula more distant from each other. All the bones of the female pelvis are more delicate, rounder, and thin ; and its diameters are greater than those of the male. The average diameters of the female pelvis are given as follows — (Fig. 145.) In the superior strait there are three, the antero-posterior, transverse, and oblique. The first extends from the middle of the promontory of FIG. 145. the sacrum to the superior part of the symphysis pu- bis, and measures about four inches. The second, or transverse, extends from the central part of the su- perior strait, on the one side, to a similar point on the opposite, and measures about five inches. The third, or oblique diameter, measures about four and a half inches, and reaches from the sacro- iliac junction to the opposite ilio-pectineal eminence. TABLE OF MEASUREMENTS OF THE MALE AND FEMALE PELVIS, BY MECKEL. MALE. FEMALE. Transverse diameter of great pelvis between anterior In. Lines. In. Lines. and superior spinous processes of ilia, 7886 Distance between crista of ilia, 8394 Transverse diameter of superior strait, 465 Oblique diameter of superior strait, 4545 Transverse diameter of the cavity, 4 48 Oblique diameter of the cavity, 5 54 Antero-posterior diameter of the cavity, 5 48 Transverse diameter of lower strait, 3 45 Antero-posterior diameter of lower strait, 33 44 This latter diameter, from the mobility of the coccyx in the female, can be increased to five inches. FIG. 145 represents the average diameters of the superior Strait of the fe- male Pelvis. 1 3 Oblique diameters. 2 Transverse. 4 Antero-posterior or sacro-pubic diameter. MUSCLES OF ANTERIOR NECK. 481 CHAPTER II. ACTIVE ORGANS OF THE TRUNK. FIRST DIVISION. ORGANS BELONGING TO THE NECK AND BACK. 1. Organs of motion — the muscles. 2. Organ of deglutition — oesophagus. 3. Organs of circulation — blood-vesssls. 4. Organs of innervation — nerves. 5. Thyroid gland. 6. Lymphatic glands. *T. Fascia of the neck. 8. Organ of voice. SECTION I. ORGANS OF MOTION — MUSCLES OF ANTERIOR NECK. Dissection. — Make an incision through the integuments along the clavicle, from the sternum to the acrornion pro- cess; a second incis- FIG. 146. ion from the chin, along the margin of the lower jaw, to the mastoid pro- cess ; connect these two l>y a third, run- ning along the me- dian line of the neck, frorn the chin to the sternum. The integument, thus marked off, should be dissected from £he chin, obliquely downward and outward towards the clavicle, embracing the whole side of FIG. 146 represents the superficial Muscles of the Neck, a Platysma my- oides, or latissimus colli. & Sterao-cleido mastoideus. c Sternal attachment. d Clavicular attachment, e Sterno-hyoideus. 31 482 MUSCLES OF ANTERIOR ISTECK. the neck. This brings to view the superficial fascia, the removal of which exposes the first superficial muscle. The platysma myoides, (7tta*uj, ^vj, «&>$, broad muscle-like lamella) or latissimus colli, consists of a very delicate, thin, pale, and broad plane of muscular fibres, situated between two layers of the superficial fascia. It is a cutaneous muscle corresponding to the panniculus carnosus of quad- rupeds. It arises below the clavicle from the cellular tissue and integument covering the pectoral and deltoid muscles, and then ascends obliquely inward upon the side of the neck, to be inserted into the cellular tissue and skin of the chin, where it intersects fibres from the opposite side, and into the fascia of the lower jaw. Its fibres are frequently traced upward, intermingling with the muscles at the angle of the mouth, and backward to the fascia covering the parotid gland. From this gland a transverse band of fibres, riso- rius santorini, have been traced to the angles of the mouth. Function. — To depress the lower jaw and angles of the mouth, and if the mouth be closed to raise the skin upon the neck. It covers and supports the muscles, vessels and glands beneath, and has the external jugular vein partly imbedded in its substance. Sterno-cleido mastoideus (Fig. 146) is situated at the lat- eral and anterior part of the neck, enclosed between two layers of the cervical fascia. It arises from the sternum by a strong flat tendon, and from the sternal third or half of the clavicle by a broad, fleshy and aponeurotic ori- gin. These two origins of this muscle include a small space of triangular shape, containing small vessels and cel- lular substance. The sternal portion is the larger, and as it ascends, overlaps the clavicular which proceeds verti- cally. About tlie middle of the neck the two are united, and thence go to be inserted into the mastoid process by a thick, round tendon, and by an aponeurosis into the outer portion of the superior transverse ridge of the occipital bone. Function. — Both muscles acting together will bend the MUSCLES OF ANTERIOR NECK. 483 FIG. 147. head forward. If the sternal portion act alone it will turn the face to the opposite side ; if the clavicular act by itself it will bend the head to the same side. If the mus- cles of the back be in strong ac- tion, this muscle can assist in still further throwing the head back- ward, as seen in that variety of tetanus called opisthotonos. It is concerned in the production of wry neck. It has in front or cover- ing it, the skin, platysma, superficial fascia, external jugular vein, portion of the parotid gland, branches of the portio-dura, and cervi- cal plexus of nerves, and at its upper part it is perforated by the spinal accessory nerve, which, however, sometimes passes behind it. The sterno-liyoideus is a long, narrow, flat muscle, sit- uated on either side of the median line of the neck, and exposed by removing the deep cervical fascia. It arises from the first bone of the sternum on its posterior surface, and the sternal end of the clavicle, ascends and is inserted into the inferior margin of the body of the os-hyoides. FIG. 147 represents the principal muscles of the neck, after turning aside the platysma myoides. a Mastoid process. 6 Hyoid bone, c Sterno hyoideus muscle, d Sterno thyroideus. t Omo hyoideus. / Origin of omo-hyoidens. g Thyroid gland, h Anterior belly of digastricus. i Posterior belly of the same, j Where the digastric tendon passes through the stylo-hyoideus. k Mylo-hyoideus. I Genio-hyoideus. m Hyo-glossus. n Thyro-hyoideus. 9 Thyroid cartilage, p Scalenus anticus. q Rectus capitis-anticus major, r Levator anguli scapula?, s Splenius. 484 MUSCLES OF ANTERIOR NECK. Function. — To draw down the os-liyoides, pharynx, and larynx. It is covered by the sternum, clavicle, and sterno- mastoid muscle at its lower portion. The sterno-tliyroideus is situated beneath the last, and is broader and shorter, being ribbon-like in its appearance. It arises from the back part of the upper bone of the ster- num and the cartilage of the first rib, ascends obliquely, and is inserted into the ala of the thyroid cartilage, upon its oblique line. Function. — To draw down the larynx. It is covered by the sterno-hyoid and mastoid muscles. The omo-liyoideus (w^oj, shoulder^) is situated obliquely across the neck, and is a long, narrow, and double-bellied muscle. It arises from the superior costa of the scapula, posterior to its semi-lunar notch, and from the ligament of this notch by a fleshy origin. It occasionally arises from the acromial end of the clavicle, and base of the coracoid process. It ascends above the clavicle and passes behind the sterno mastoid muscle, where it becomes tendinous. After this it again becomes fleshy and is inserted into the inferior border of the os-hyoides, at the junction of its body and cornu. Function. — To draw the os-hyoides downward and back- ward, and assist in deglutition. Its origin is concealed by the trapezius; it crosses the carotid artery and internal jugular vein, and its insertion is covered by the fascia and integuments. The two sterno-mastoid muscles, with the omo-liyoid, and the anterior edge of the trapezius, to be presently noticed, form several triangles very important in a surgical point of view, and recognizable in the living subject. The two sterno-mastoid muscles, coming together at the sternum, form the apex of a large triangular space on the front of the neck, the sides of which are formed by the diver- gence of these same muscles, to the mastoid processes, while the base of this triangle is above, and constituted by the lower jaw. The median line of the neck divides this triangle into two, called the anterior lateral triangles of the neck. TRIANGLES OF THE NECK. 485 On the outside of the mastoid muscle, and between its posterior edge and the anterior edge of the trapezius, there is another triangular space, having its base below, resting on the clavicle — its apex above, at the mastoid process, where the muscles meet, while its sides are formed by the same muscles. This space is called the posterior lateral triangle of the neck. Each of these large triangular spaces is crossed by the omo-hyoideus muscle, which divides each of them into two, and consequently makes four triangles on each side of the median line of the neck. These are named as fol- lows : 1. Anterior superior. 2. Anterior inferior. 3. Pos- terior superior. 4. Posterior inferior. Of these triangles, the anterior superior and posterior inferior seem, practically, the most important, as in the former we tie the carotid artery, and in the latter, the subclavian. It may be well here to notice the contents of each of these triangles. The anterior superior triangle is situated between the anterior belly of the omo-hyoid, and the sterno mastoid, the apex of the triangle being formed by the intersection of these muscles opposite the cricoid cartilage, and the base, which is superior, by the digastric muscle. The carotid artery, the internal jugular vein, the par-vagum, and the sympatlietic nerves, are found in this triangle, simply cov- ered by the fascia, the platysma, and the integuments. The anterior inferior triangle is situated below the ante- rior belly of the orno-hyoid, and between it and the median line of the neck, above the sternal end of the clavicle ; it also contains the carotid artery, the jugular vein, and the accompanying nerves, and is covered by the sterno-mastoid, sterno-hyoid, and sterno-thyroid muscles. A portion of the thyroid gland is also seen in this triangle. The posterior superior triangle is between the trapezius and sterno-mastoid, and above the posterior belly of the omo-hyoid muscle; it contains cellular tissue, lymphatic glands, and the cervical plexus of nerves. The posterior inferior triangle is below the posterior belly 486 MUSCLES OF ANTERIOR NECK. of the omo-hyoid, above the clavicle, and behind the poste- rior inferior margin of the sterno-mastoid. The sub-davian artery and some of its branches, with the vein and brachial plexus of nerves, are seen in this triangle. The scalenus anticus muscle is situated at the lower and anterior part of the neck, and is considered to be contin- uous with the rectus capitis FJG. 143. anticus major. It arises ten- dinous from the third, fourth, fifth, and sixth transverse pro- cesses of the cervical vertebrae, and is inserted into the su- perior surface of the first rib at its sternal end. The scalenus medius is larger than the last and arises from the transverse processes of all the cervical vertebrae by tendin- ous fibres. Sometimes it orig- inates only from the four or five lower cervical vertebrae. It is inserted into the superior sur- face of the first rib posterior to the subclavian artery. The scalenus posticus is behind the former, and is better seen in dissecting the muscles of the spine. It arises from the transverse processes of the two or three lower cervical ver- tebrae, and is inserted into the superior surface of the second rib between its tubercle and angle. The two last muscles are by some regarded as a single one, and described as such. Function. — The three scaleni bend the neck forward or to one side, and when the vertebrae are fixed, elevate the ribs. The first scalenus has the phrenic nerve descending on the front, the subclavian vein crossing its insertion, the sub- FIG. 148 represents the deep Muscles of the anterior Neck, a Rectus capi- is anticus major, d Rectus capitis anticus minor, j Rectus capitis lateralis. 6 Scalenus anticus. g Scalenus medius. h Scalenus posticus. c f Longus colli— its lower portion on the right side, and upper portion on the left side, i One of the intertransversales. MUSCLES OF ANTERIOR NECK. 48T daman artery and brachial plexus behind it, and the sterno- mastoid and omo-hyoid muscles in front. The second scalenus or medius has the subclavian and brachial plexus in front, and is covered by the first. The longus colli is situated close upon the bodies of the vertebras, upon either side of the median line. It arises from the bodies of the three superior dorsal vertebras at their sides, and from the transverse processes of the lower cervical vertebras, and also occasionally by a slip from tho first and second rib. Its insertion is into the front of the bodies of the cervical vertebrae. Function. — To bend the neck directly forward and to the one side. The division of this muscle into a superior and inferior portion, has led to some apparent discrepancy among anatomists, as to its origin and insertion, though there is general uniformity as to its several attachments. Upon this muscle rests the pharynx, oesophagus, and the great cervical vessels and nerves with their sheaths. Rectus capitis anticus major. — At the superior and ante- rior part of the neck there are three recti muscles, the major, minor, and later alls. Dissection. — These are deep muscles, and are seen along with the longus colli, on the removal of the oesophagus and pharynx. The rectus capitis anticus major arises tendinous from the transverse processes of the four lower cervical vertebrae. The four tendons ascend, and becoming fleshy, proceed obliquely inward, forming a broad and thick muscle, which is inserted into the cuneiform process of the occipital bone, just in front of the condyle. Function. — To bend the head and also the neck forward. Eectus capitis anticus minor is a small and narrow mus- cle. It arises from the front of the atlas near its trans- verse process, and is inserted into the cuneiform process of the occipital bone, beneath the rectus major. Function. — To bend the. head forward and to one side. The superior cervical ganglion of the sympathetic rests in part upon this muscle. 488 MUSCLES ON POSTERIOR NECK AND BACK. Eectus capitis lateralis arises from the transverse pro- cess of the atlas, and is inserted into the jugular eminence of the occipital bone on the outside of its condyle. It is a very short muscle, and its function is to bend the head to the one side. It covers the vertebral artery and has the jugular vein resting upon it. SECTION II. ORGANS OF MOTION, OR MUSCLES ON POSTERIOR NECK AND BACK. Dissection. — Eaise the chest by placing a block beneath it, and let the arms and head hang, so as to make the mus- cles and integument tense. Commence an incision from the external occipital protuberance, which carry along the Bpinous processes to the coccyx. Make a second from the lower cervical spine, to the acromion process ; and a third from the occipital protuberance, along the superior trans- verse ridge, towards the mastoid process. Commence the dissection at the second incision, and raise the skin upward and downward, dissecting always in the course of the fibres of the muscle, and taking care to take oif the cellular struc- ture, along with the integument, so as to leave the muscles clean and distinct. The muscles of the posterior neck and of the back have been divided into six layers. The first layer is superficial, and consists of two muscles, the trapezius and latissimus dorsi. The Trapezius, so called from its resemblance to the mathematical figure of that name, is a triangular, broad muscle, having its base at the spine, and apex at the acro- mion process of the scapula. It is situated on the back part of the neck and chest, and arises from the external occipital protuberance and its superior transverse ridge, by a thin aponeurotic tendon ; also from the spinous processes of the five superior cervical vertebras, by the ligamentum jmchre ; and again tendinous from the spinous processes of the two lower cervical, and all the dorsal. The superior fibres descend, the inferior ascend, and the middle rim transversely, all converging towards the shoulder, to bo MUSCLES ON POSTERIOR NECK AND BACK. 489 inserted into the outer third of the clavicle, the acromion process, and the superior edge of the spine of the scapula. Function.— -To draw the shoulder toward the spine. Its superior fibres can also raise the shoulder, while the in- ferior can depress it. FIG. 149. The head can also he inclined backward and to the one side by it. The ligamentum nu- chce is composed of cellulo-1 igainentous matter, broad above, extending from the ex- ternal occipital protu- berance along the me- dian line, and attached to the spinous pro- cesses of all the cervi- cal vertebras. It forms a complete partition between the muscles upon the two sides of the neck. It is very powerful in the ox, and is of great use in supporting the head and in giving attach- ment to muscles. The latissimus dorsi, as its name implies, is truly the broad muscle of the back. It is situated immediately be- neath the skin, covering the whole of the lower part of the back and loins, and arises by a thin tendinous membrane, from the six inferior spines of the back, and by the fascia lumborum, from all the spines of the loins and sacrum ; also FIG. 149 represents the Superficial Muscles of the back and neck. 1 Trape- zius. 2 Latissimus-dorsi. 3 Infra-spinatus. 4 Teres minor. 5 Teres major. 6 Obliquus externus. 7 Serratus magnus. 8 Pectoralis major. 11 Sterno- mastoid. 12 Deltoid. 16 Gluteus maximus. 490 MUSCLES ON POSTERIOR NECK AND BACK. from the posterior third of the crest of the ilium, and by fleshy slips from the three or four lower ribs. The fibres from this extensive origin converge towards the axilla, so as to form its posterior fold; and thence go to be inserted by a broad, thick tendon, into the lower part of the posterior edge of the bicipital groove of the humerus. As this mus- cle ascends, it passes over the inferior angle of the scapula, where a bursa is found interposed, and where also a fasci- culus of fibres often connects the two. At this point it is behind the teres major, but as it proceeds it winds around this muscle so as to get in front. The two tendons are closely connected, but separated by a bursa. Function. — To draw the arm downward and backward. It can also depress the shoulder and rotate the humerus in- wards, and if the shoulders be fixed it can elevate the ribs and assist in inspiration. The second layer consists of three muscles. Bliomboideus minor. — Dissection. — Cut through the trape- zius along its spinal attachment, and reflect towards the shoulder, which will expose the rhomboidei. This is a nar- now muscle, and seems more properly to form a part of the next, the rhomboideus major, with which it is so intimately blended. It arises by a thin tendon from the two or three lower cervical spines, passes obliquely down and is inserted into the base of the scapula opposite its spine. The rhomboideus major arises tendinous from the four su- perior dorsal spines, passes down parallel and in connection with the rhomboideus minor, and is inserted into all the base of the scapula from its spine to the inferior angle. These two muscles receive their name from their quadri- lateral figure. Function. — To draw the shoulder backward and upward toward the spine. The levator anguli scapulae is situated at the upper and posterior side of the neck, between the anterior margin of the trapezius and the posterior margin of the sterno-cleido- mastoideus. It arises by distinct and rounded tendons from the transverse processes of the four or five superior cervical MUSCLES OX POSTERIOR NECK AND BACK. 491 FIG. 150. vertebrae ; these unite to form a fleshy belly, which is inserted into all the base of the scapula from its spine to the superior angle. Function. — To raise the shoulder, when acting with the trapezius. When act- ing by itself it elevates the superior angle of the scapula, and in propor- tion depress- es the acro- mion. Third lay- er.— Dissec- tion.— Ke- move the rhomboidei by detach- ing them from the base of the scapula, and the latissi- rnus dor si, by dividing along its centre and reflecting towards the spine, and the third layer is exposed, which consists of the three follow- ing muscles : The serratus posticus superior, situated at the upper and FIG. 150 represents the Muscles of the Back, seen after removing the super- ficial set. 1 Trapezius. 2 Tendon of the two trapezii. 3 Spine of scapula. 4 Latissimus dorsi. 5 Deltoid. 6 Infra-spinatus, teres-minor. 7 External oblique. 8 Gluteus medius. 9 Gluteus maximus. 10 Levator scapulae. 11 Rhomboideus minor. 12 Rhomboideus major. 13 14 Splenius capitis etcolli. 15 Origin of latissimus dorsi. 16 Serratus posticus inferior. 17 Supra spina- tus. 18 Infra-spinatus. 19 Teres minor. 20 Teres major. 21 Long head of triceps extensor cubiti. 22 Serratus major anticus. 23 Internal oblique. 492 MUSCLES ON POSTERIOR NECK AND BACK. back part of the chest, arises -"by a thin aponeurotic tendon, from the ligamentum nuchee, the three inferior spines of the neck, and from the two or three superior spines of the back, and is inserted lay fleshy digitations into the upper edges of the second, third, and fourth ribs. Function. — To elevate the ribs, and thus, by expanding the chest, to assist in inspiration. The serratus posticus inferior, situated at the lower and back part of the chest,, is a broader and thinner muscle than the last. It arises, by a very delicate tendinous ex- pansion, beneath the latissimus dorsi, with which it is strongly connected, through the fascia lumborum; from the spinous processes of the two lower dorsal, and two or three upper lumbar vertebra?, and is inserted, by fleshy digitations, into the inferior margins of the four lower ribs, Function. — To depress the ribs, and thus by lessening the capacity of the chest, to assist in expiration. It is the antagonist muscle of the superior serratus. The splenius capitis et colli has its lower portion con- cealed by the muscle before the last ; and its upper, by the trapezius. It arises from the four or five superior spines of the back, and the three or four lower of the neck, and from the ligamentum nucha?; it ascends as a long, flat, and fleshy muscle, and is inserted, by two distinct portions — one for the head — into the mas toid process of the temporal bone, and the surface between the two semicircular ridges of the occipital ; and the other, for the neck, into the transverse processes of the two or three superior cervical vertebra?. Function. — To bend the head and neck backward. The fourth layer is seen by removing the serrati and splenii, and consists of the following seven muscles : Sacro-lumbalis , longissimus dorsi, spinalis dorsi. These three muscles are associated under the name of erector spinw. The whole appear as one mass, occupying the space between the spinous processes and the angles of the ribs. The first two have a common origin from the posterior surface of the sacrum, from the posterior third of the crest of the ilium, and from the spinous and oblique processes of MUSCLES ON POSTERIOR NECK AND BACK. 493 the lumbar vertebrae ; on a level with the last rib a division occurs. The sacro-lumbalis forms the outermost and larger portion, and is inserted by long and slender tendons, into all the ribs at their angles. The longissimus dorsi is nearest the spine, and is inserted by short tendons into the transverse processes of all the dorsal vertebra^ and by tendinous and fleshy slips into all the ribs between their tubercles and angles. Function. — These two muscles ex- tend the spine, and preserve it in the erect state. On separating these muscles, six or eight tendinous and fleshy slips are seen coming from the superior margin of the ribs and attaching themselves to the lower surface of the sacro-lumbalis ; they are called the musculi accessorii ad sacro-lumbalem. The spinalis dorsi is a purely ten- dinous muscle, situated along the edges of the spinous processes. It arises tendinous from the two supe- rior lumbar and three inferior dorsal spines, and is inserted tendinous into the nine upper dorsal spines. Function. — The same as the two last. These three muscles are covered by the fas da lumborum. The cervicalis ascendens or descendens, appears to be a continuation of the sacro-lumbalis. It arises from the upper FIG. 151 represents the deep Muscles of the back and neck. 1 3 Longissi- mus dorsi, its lower and upper portions. 2 Upper part of sacro-lumbalis. 4 Spinalis dorsi. 5 Cervicalis descendens. 6 Transversalis cervicis. 7 Trachelo mastoideus. 8 Complexus. 9 Transversalis cervicis, its insertion. 10 Semi- spinalis dorsi. 11 Semi-spinalis colli. 12 Rectus capitis-posticus-minor. 13 Rectus capitis-posticus major. 14 Obliquus capitis superior. 15 Obliquus ca- pitis inferior. 16 Multifides spina3. 17 17 Levatores costarum. 18 Inter- transversales. 19 Quadratus lumborum. 494 MUSCLES ON POSTERIOR NECK AND BACK. edges of the four or five superior ribs, by as many tendons, and forms a small fleshy belly, which is inserted by three or four tendons into the transverse processes of the fourth, fifth, and sixth cervical vertebras. Function. — To draw the neck backward and to one side. Transversalis colli (or cervicis) appears to be a continua- tion of the longissimus dorsi, and is about the same size with the last. It arises from the transverse processes of the four or six superior dorsal, and is inserted by small ten- dons into the transverse processes of the four or five lower cervical vertebrae. Function. — To draw the neck backward. The tracJielo-mastoideus , situated between the last and the complexus, seems also to be a continuation of the longissi- mus dorsi, upward. It arises tendinous from the transverse processes of the three or four superior dorsal, and four or five inferior cervical, and forms a very delicate and slender muscle, which ascends to be inserted into the posterior part of the mastoid process, beneath the splenius. Function. — To bend the head and neck backward and to rotate to one side. The complexus is seen between the upper heads of the diverging splenii, and is a large and thick muscle. The tendinous matter noticed in its substance, gives it the com- plex appearance, whence its name is derived. It arises from the transverse and oblique processes of the five or seven superior dorsal, and three or four inferior cervical, and is inserted into the occipital bone, along with its fel- low, on either side of the median line, between the two semicircular ridges. Function. — To draw the head back. Fifth layer, (Fig. 151.) — Dissection. — Kemove the muscles of the fourth layer, by dividing them in their middle and reflecting them to either end. This layer consists of the following five muscles : The rectus capitis rjosticus major, is of a triangular shape, arises, tendinous and fleshy, from the spinous process of the vertebra dentata, and is inserted broad into the inferior transverse ridge of the os-occipitis. Function. — To draw the head back and rotate it on the atlas. The rectus capitis posticus minor, like the last, is also MUSCLES ON POSTERIOR NECK AND BACK. 495 triangular, having its apex below and "base above, being situated to the inner side of the rectus major, and with it occupying the space between the head and the first and second vertebrae. It arises from the tubercle on the poste- rior part of the atlas, and passes upward and outward to be inserted broad into the rough surface between the infe- rior transverse ridge, and foramen magnum of the occipital bone. Function. — To draw the head backward. The obliquus capitis superior arises narrow from the transverse process of the atlas, and is inserted, by a broad attachment to the occipital bone, behind its mastoid pro- cess, function. — To bend the head to one side and draw it backward. The obliquus capitis inferior arises from the spinous pro- cess of the vertebra dentata, passes upward and outward, and is inserted into the extremity of the transverse process of the. atlas. Function. — To rotate the atlas and head upon the dentata or second vertebra. These four little muscles form nearly an equi-lateral triangle. The base Consists of the recti along the middle line. The apex is the extremity of the transverse process, and the sides of the triangle are the superior and inferior oblique muscles. A quantity of fatty and cellular struc- ture fills up this triangle, and deep in it are seen the verte- bral artery, a plexus of veins, and the sub-occipital nerve. The semi-spinalis colli et dorsi appears as one continued muscle, though it has been distinguished into two. They extend from transverse to spinous processes, encircling about one-half the vertebral column — hence their name. They are with difficulty distinguished from the multifidus spinae. The semi-spinales colli arise from the transverse processes of the five superior dorsal vertebrae, and are inserted into the spinous processes of the middle cervical vertebrae. The semi-spinales dorsi arise from the transverse pro- cesses of the six lower dorsal vertebrae, and are inserted into the spinous processes of the two lower cervical, and four upper dorsal. Function. — To draw the spine obliquely backward. 496 MUSCLES ON POSTERIOR KECK AND BACK. Sixth layer, (Fig 151.) — Dissection.— Eemove tlie semi- spinales. This layer consists of the deeper and more deli- cate muscles of the back and ribs. The inter-spinales , as their name implies, are situated "between the spinous processes of contiguous vertebras. They consist of a succession of small, short muscles, which, in the neck, are in pairs, owing to the bifid state of the cervical spines. In the back they are quite indistinct, and in the loins they are mostly ligamentous, having a few muscular fibres intermixed. Function. — To extend the spine and keep it erect. The intertransversales are also short muscles, and as their name indicates, are situated between the transverse processes. They are double and distinct in the neck, very indistinct in the back, and feeble in the loins. Function. — To bend the spine laterally. The multifidus spince consist of a multitude of small, fleshy and tendinous fasciculi, which are parallel to each other, and extend from transverse to spinous processes, the whole length of the spine. They arise each from the trans- verse or oblique piocess of one vertebra, and are inserted into the spinous process of the vertebra above, the fasci- culi sometimes extending to the second or third vertebra above. At the lower part of the spine the multifidus spinaa have also an attachment, tendinous and fleshy, to the back part of the sacrum, and the posterior part of the ilium. Function. — To support the spine and bend it to one side. The levatores costarum are twelve in number, on each side of the chest, and are parallel to the external intercos- tal muscles. Each arises from the transverse processes of the dorsal and the last cervical vertebra, and is inserted into the ribs below, between the tubercle and angle. Func- tion.— To elevate the ribs and assist in inspiration. The supra-spinales are little fleshy fasciculi,, or bands, described as being situated exclusively upon the spinous processes of the cervical vertebrae It will be seen from the above description of the muscles (ESOPHAGUS. 49 T of the back, that no very great regularity belongs to their several attachments, a fact which explains the apparent discrepancy among different authors. SECTION III. ORGANS OF DEGLUTITION — CESOPHAGUS. The oesophagus, (own/, to bear, $ay°?> food,) or food duct, is a continuation of the pharynx, and, as its name implies, is designed to convey our food and drinks from the mouth and pharynx downward into the stomach. It commences at the lower portion of the pharynx, op- posite the fifth cervical vertebra, and behind the cricoid cartilage, at its lower border. It then descends the neck nearly on the median line, lying first a little to the left of this line in the neck, then inclining, as it enters the chest, to the right; then again to the left, before it enters the stomach. This flexuosity explains the occasional dif- ficulty of introducing the probang. It passes behind the trachea, the arch of the aorta, the pericardium, along the posterior mediastinum, and in front of the thoracic aorta, to the diaphragm, and terminates at the cardiac orifice of the stomach, opposite the tenth dorsal vertebra. It is made up of three distinct coats, with the blood-vessels and nerves. The coats are the external, the middle, and the internal, or muscular, cellular, and mucous. The muscular coat is composed of two very distinct planes of fibres — the external, running longitudinally, and the internal, circularly, both being prolonged upon the stomach. The cellular coat forms the connecting medium between the muscular and mucous coats, and conducts the blood-vessels and nerves to the latter. The mucous coat is pale, thin, disposed in longitudinal folds, and covered by a delicate epithelium or cuticle. It also contains mucous follicles, sometimes called cesophageal glands, whose orifices are seen in the depressions between the longitudinal folds. The arteries of the oasophagus come from the inferior thyroid in the neck ; from the bronchial and aorta in the chest ; and from the diaphragmatic and coronary artery of 32 498 PNEUMOGASTRIC NERVE. FIG. 152. the stomach. Its veins enter the inferior thyroid, the bronchial, vena azygos, superior vena cava, internal mammary, and coronary vein of the stomach. It has also lymphatics dis- charging their contents into the ganglia which surround it. The nerves of the oesophagus are numerous and consist chiefly of branches from the pneumo-gastric, which surround it and constitute the cesophageal plexus. The pneumo-gastric, (Fig. 152,) or par vagum, being so largely con- nected with the oesophagus, as well as with a variety of other important organs, demands a description in this place. This nerve, (classed along with the eighth pair, though a more strict classification makes it the tenth,) arises by numerous fila- ments, generally ten or twelve, from the medulla oblongata in the fissure between the corpora olivare and res- tiforme. These unite into one nerve, which joins the glosso-pharyngeal above, and the spinal accessory be- low, and the whole proceed to the foramen lacerum posterius, through FIG. 152 represents the eighth pair of nerves. 1 Corpus pyramidale. 2 Pons Varolii. 3 Corpus olivare. 4 Corpus restiforme. 5 Facial nerve. 6 Origin of glosso-pharyngeal. 7 Ganglionum petrosum. 8 Trunk of glosso-pharyn- geal. 9 Spinal accessory. 10 Ganglion of par-vagum or pneumogastric nerve. 11 Its ganglion taking the plexiform arrangement. 12 Trunk of par vagum. 13 Its pharyngeal branch. 14 Pharyngeal plexus. 15 Superior laryngeal nerve. 16 Cardiac branches. 17 Recurrent branch. 18 Anterior pulmonary branches. 19 Posterior pulmonary branches. 20 (Esophageal plexus. 2J Gastric branches. 22 Point where spinal accessory arises. 23 Sterno-mastoid branches. 24 Branches to the trapezius. PNEUMOGASTRIC NERVE. 499 which they pass, and go to their several destinations. In the foramen lacerum, the par vagum is separated from the other nerves by dense cellular membrane, and from the jugular vein, which is behind, by a spicula of bone. At this point it also presents a swelling called the superior ganglion, and below this another enlargement called the inferior gangli6n, about an inch in length. From these, filaments communicate with the facial, spinal accessory, glosso-pharyngeal, sympathetic, and superior spinal nerves, constituting a plexus termed the basilar plexus. From the inferior ganglion, which is of reddish color, the par vagum descends the forepart of the neck, along with the carotid artery and jugular vein, behind and between those vessels, and enclosed in the same sheath with them. At the root of the neck, the right par vagum enters the chest between the subclavian vein and artery, crossing the latter at right angles ; on the left, this nerve runs parallel to the sub- clavian artery, crossing the arch of the aorta. Both nerves now proceed through the thorax to the posterior part of the root of the lungs, in the posterior mediastinum, and descend along the oesophagus, through the diaphtagni, to terminate upon the stomach. The par vagum in its course gives off the following branches : The auricular commences at the superior ganglion, con- nects with the glosso-pharyngeal, enters a small canal of the petrous bone, upon the inside of the styloid process, then proceeds to join the facial in the aqueduct of Fallo- pius, and finally escapes in front of the mastoid process to supply the ear and its integuments. The pliaryngeal comes from the inferior ganglion at the base of the cranium, receives a branch from the spinal acces- sory, and descends behind the carotid artery to the side of the pharynx, at the upper margin of its middle constrictor. Here it anastomoses with branches from the glosso-pharyn- geal, the superior laryngeal, and the sympathetic, forming the pharyngeal plexus , which supplies the mucous and mus- cular structures of the pharynx. 500 PNEUMOGASTRIC NERVE. The superior laryngeal also arises from the inferior gang- lion, and taking an arched course downward behind the internal carotid artery, enters the thyro-hyoid membrane along with the superior laryngeal artery, and principally supplies the mucous membrane of the larynx. This nerve is regarded as one of sensation. The cardiac nerves have their origin from the vagus at the root of the neck, by two or three branches, which cross the carotid artery and join the sympathetic in the cardiac plexus. The inferior laryngeal (or recurrent nerve) comes from the par vagurn upon the right side, as it crosses the sub- clavian artery. It curves around and behind this artery, and ascends to the larynx along the side of the trachea, covered by the inferior thyroid and common carotid arte- ries ; at its origin it gives off filaments to the cardiac plexus, trachea, oesophagus, and thyroid gland, and finally termin- ates by supplying all the muscles of the larynx except the crico-thyroid. Branches have also been traced into the mucous membrane of the larynx. The recurrent of the left side differs from that of the right, in curving round the arch of the aorta and ductus arteriosus. The recurrent, or inferior laryngeal nerves are essentially motor. Pulmonary brandies. — These come from the vagus, near the root of the lungs, and form a plexus, in front and be- hind the root, called the anterior and posterior pulmonary plexuses. The posterior is the larger, and both anastomose with the sympathetic and phrenic nerves, and accompany the pulmonary vessels and bronchial tubes, to supply the lungs. (Esopliageal branches. — These come from the pneumogas- tric above and below the root of the lung; but it is below the root that the nerves, on either side, come together, and,, surrounding the oesophagus, constitute the cesophageal plexus. The left vagus goes in front, while the right passes behind the cesophagus. Gastric branches. — These are the terminating branches of the pneumogastric upon the stomach. They form, around BLOOD-VESSELS OF THE NECK. 501 the cardiac orifice of the stomach, the cardiac plexus. The right vagus goes to the posterior surface of the stomach, communicating with the solar, renal, splenic, and hepatic plexuses; while the left is distributed on the anterior surface, and lesser curvature of the stomach, sending some branches, by the lesser omentum, to the liver and gall- bladder. It is evident, then, that the pneumogastric is a com- pound nerve, that is, that it combines filaments of sensa- tion and motion — that it connects together a great variety of organs, as the pharynx, oesophagus, larynx, trachea, lungs, heart, and stomach, and influences an equally great variety of functions, as deglutition, voice, respiration, cir- culation, and digestion. The oesophagus, besides the pneumogastric nerves, i« also supplied with branches from the thoracic ganglia of the sympathetic. SECTION IV. ORGANS OF CIRCULATION OF THE NECK. The organs of circulation in the neck comprise its blood- vessels, and consist of the arteries and veins. The arteries supplying the upper part of the neck are, the superior thyroid, facial, and occipital — branches of the external carotid. The vertebral, the thyroid axis, and the cervicalis posterior, supply the lower part of the neck, and come from the subdavian. The external carotid has been stated elsewhere, to arise from the common carotid, and this latter to arise from the arteria innominata, upon the right side, opposite the sterno- clavicular articulation, and upon the left, from the arch of the aorta. Both common carotids now ascend the neck nearly in a vertical direction,, having in front, at their ori- gin, the sterno-thyroid, the sterno-hyoid, and sterno-mastoid muscles ; the descendens noni nerve along the middle front, and outside the sheath of the vessels, while the omo-hyoid- eus crosses in front about their middle. On the inside are 502 BLOOD-VESSELS OF THE NECK. seen the larynx, the trachea, oesophagus, and thyroid gland; on the outside, the internal jugular vein in the same sheath with the artery; "behind, these vessels rest upon the transverse processes of the cervical vertebra, the longus colli, and rectus capitis anticus major muscles, the FIG. 153. 37- 4S inferior thyroid arteries, and the inferior laryngeal and sympathetic nerves. The common carotids are also cov- ered in front hy the common integuments, platysma my- oides, and superficial fascia of the neck. FIG. 153 represents the Anterior Neck, showing its Blood-vessel, &c. &c. 1 Anterior bellies of the digastric muscle. 2 3 Mylo-hyoideus. 4 Hyo-glos- sus. 5 Stylo-glossus. 6 Styloid process. 7 Bifurcation of external carotid into internal maxillary and temporal. 8 Posterior auricular branch of the facial nerve and artery. 9 Stylo-pharyngeus, and middle constrictor of the pharynx. 11 Mastoid branch of external carotid. 12 Superior thyroid ar- tery. 13 Thyro-hyoid membrane. 14 Thyro hyoid muscle. 15 15 Sterno- Ihyroid. 16 Thyroid gland. 17 17 Omo-hyoid muscle. 18 18 Sterno hyoid. 19 Sterno-mastoid. 20 Upper attachment of the sterno-mastoid. 22 Obliquus capitis-superior. 23 Complexus muscle. 24 Splenius capitis. 25 Levator anguli scapulaj. 26 Scalenus posticus. a Scalenus medius. b Scalenus an- BLOOD-VESSELS OF THE NECK. 503 Each common carotid terminates opposite the upper bor- der of the thyroid cartilage, by dividing into the external and internal carotids. From this point, the external carotid ascends to the neck of the lower jaw, where it ends in the temporal and inter- nal maxillary arteries. In this course it is crossed, near its origin, by the lingual nerve, then by the stylo-hyoid and digastric muscles ; and, still higher, it is imbedded in the parotid gland, and crossed by the facial nerve. The pla- tysma, superficial fascia, and skin form the superficial covering in front, while behind, it is separated from the internal carotid, by the stylo-glossus and stylo-pharyngeus muscles, and the glosso-pharyngeal nerve. The external carotid gives off ten branches, which have been already detailed in describing those of the head. We shall, therefore, only recapitulate here those belonging to the neck. The superior thyroid, arising from the anterior part of the external carotid, near its origin, descends beneath the omo-hyoid and sterno-thyroid muscles, to the thyroid gland. In its course it gives off the following branches : Superficial branches to the integuments and superficial muscles ; hyoid, to the lower border of the hyoid bone and its muscles ; superior laryngeal, which goes along with the superior laryngeal nerve, through the thyro-hyoid mem- brane, and is distributed to the mucous membrane and muscles of the larynx ; inferior laryngeal, supplying the ticus. c Common carotid artery, d d Subclavian. e Brachial plexus. / g Internal jugular vein, h Inferior constrictor, i (Esophagus, j Trapezius. k Deltoid. / Pectoralis major — its clavicular portion, m Its sternal portion. n Subclavius muscle, o Axillary artery. 27 Facial artery. 28 Its submen- tal branch. 29 Hypoglossal nerve. 30 Lingual artery. 31 External carotid. 32 Posterior auricular artery. 33 Facial nerve. 34 Glosso-pharyngeal nerve. 35 Occipital artery. 36 Superior laryngeal nerve. 37 Descendens noni nerve. 38 Spinal accessory nerve. 39 Princeps cervicis artery. 40 supra- scapular artery. 41 Transversalis colli. 42 Thyroid axis. 43 Inferior thyroid artery. 44 Vertebral artery. 45 Par vagum nerve. 46 Internal mammary artery. 47 Phrenic nerve. 48 Communicating nerve. 49 Second, third, and fourth cervical nerves. 50 Cervical plexus. 51 Cervicalis ascendens artery. 52 Brachial plexus. 504 BLOOD-VESSELS OF THE NECK. crico-thyroid membrane, and entering into the interior of the thyroid gland, and anastomosing freely with the inferior thyroid. The facial artery, called also the labial, or external max- illary, arises also from the front of the external carotid, opposite the os-hyoides, and ascends to the lower jaw behind, and in the substance of the submaxillary gland. Thence it proceeds to the angle of the mouth, and thence by the side of the nose, to the angle of the eye, where it terminates by anastomosing with the ophthalmic. Its branches supplying any portion of the neck, are chiefly the glandular, distributed to the submaxillary and lymphatic glands, and the submental, which leaves the facial just as it is mounting over the lower jaw, and proceeds forward, covered by this bone, passing over the anterior belly of the digastricus, and beneath the origin of the mylo-hyoideus to the chin, which, with the adjacent muscles, it supplies, and ends by anastomosing with the inferior dental and eublingual branches. The occipital arises opposite the facial, from the posterior part of the external carotid, and ascends backward behind the posterior belly of the digastric, the sterno-mastoid, and trachelo-mastoid muscles, to the groove at the root of the mastoid portion of the temporal bone. It now proceeds horizontally backward, between the splenius and complexus muscles, to the mesial line of the atlas, and thence ascends upon the occiput, terminating in numerous branches which anastomose with its fellow, the posterior auricular, and the temporal arteries. Its cervical branches supply the superficial and deep muscles on the posterior and superior part of the neck. The arteria princeps cervicis is the name applied to the deep branch which descends to the com- plexus and semi-spinalis muscles, and anastomoses with the profunda cervicis of the subclavian, thus forming the collateral circulation between the branches of the external carotid and subclavian arteries. The subclavian artery, (Figs. 120, 1535) on the right side, arises from the arteria innominata, opposite the sterno-cla- BLOOD-VESSELS OF THE NECK. 505 vicular articulation ; thence it proceeds obliquely outward to the inner margin of the scalenus anticus muscle, con- stituting its first stage. It now passes between the scale- nus anticus and scalenus medius, forming its second stage. After emerging from these muscles it proceeds downward and outward, beneath the clavicle, to the lower margin of the first rib, forming its third stage, where it terminates as subclavian, and becomes axillary. The right subclavian has anterior to it, in its first stage, the internal jugular and subclavian veins, the pneumo- gastric, phrenic, and cardiac nerves ; the sterno-mastoid, sterno-hyoid and sterno-thyroid muscles. Behind are the inferior laryngeal and sympathetic nerves, the vertebral vein, and some cellular tissue and lymphatic glands. In its second stage it lies between the scaleni muscles, separated by the scalenus anticus from the subclavian vein and phrenic nerve, and accompanied by the brachial plexus of nerves. In the third stage the subclavian vein, the subclavian mus- cle, and the clavicle are in front ; the brachial plexus and the omo-hyoid are above and external, and behind are the scalenus posticus and the first rib, while the skin, platysma, and fascia form the superficial covering. The left subclavian differs from the right in having its origin from the arch of the aorta ; in being longer ; in pur- suing nearly a vertical course to the scaleni muscles ; in having the pneumogastric running parallel with instead of crossing it ; in not having the recurrent passing around it ', in having the vena innominata, left carotid, left lung, and pleura in front ; and in having the thoracic duct and lon- gus colli muscle behind. In the second and third stages the relations of the subclavian are nearly the same on both sides. BRANCHES OF THE SUBCLAVIAN SUPPLYING THE NECK. The vertebral artery is the largest branch, and comes off from the subclavian at its upper and posterior part. It then ascends upon the vertebral column behind the inferior thy- roid artery, and after a short course enters the foramen in 506 BLOOD-VESSELS OF THE NECK. the transverse process of the fifth or sixth, and sometimes o^ the seventh cervical vertehra. It passes upward in the "bony canal formed by the several foramina placed one above another in the corresponding transverse processes, as high as the dentata or second vertebra. Here it bends outward and backward to the foramen in the transverse process of the atlas, and then makes a very remarkable curve inward and backward, round the articulation of the atlas, entering the foramen magnum through the dura mater. It ascends upon the medulla oblongata, and at the lower margin of the pons, it unites with its fellow to form the basilar artery. In the canal the vertebral artery sends out anterior, pos* terior, and external branches, supplying the intertransver- sales, complexus, splenius, rectus capitis anticus major, and scaleni muscles ; while its internal branches go into the spinal canal and supply the dura mater, and spinal marrow. In its transverse bend, between the atlas and occiput, it distributes a number of branches to the posterior recti and oblique muscles of the head. It supplies also the spinal nerves, and at the foramen magnum gives off the anterior and posterior spinal arteries that descend the cord its whole length. The remaining branches of the vertebral and basilar arteries, are given in the account of the brain. The thyroid axis arises from the subclavian at its upper part and near the inner edge of the scalenus anticus. It is a short, thick trunk, and gives off four principal branches : The inferior thyroidj the superior scapular or transver- salis humerij the posterior scapular or transversalis collij and the cervicalis anterior or ascending cervical. The inferior thyroid ascends behind the common carotid to the thyroid gland, where it anastomoses with the supe- rior thyroid, supplying in its course the trachea, oesopha- gus, and lower part of the larynx. The superior scapular proceeds behind the clavicle ob- liquely outward to the supra scapular-notch, over whose ligament it passes to supply the supra-spinatus, and then goes beneath the acromion to the infra-spinatus and teres BLOOD-VESSELS OF THE NECK. 507 minor. In its course it crosses the scalenus anticus, the phrenic nerve, and the brachial plexus. This vessel not unfrequently comes from the subclavian. The transversalis colli, or posterior scapular passes trans- versely outward over the scaleni muscles, and through the brachial plexus to the superior posterior angle of the sca- pula, where it ends* in two branches, the superficial cervical, supplying the trapezius, splenius, and levator scapulae ; and the continued trunk, the posterior scapular, which descends along the base of the scapula to supply the rhomboid and other muscles arising from this quarter. It anastomoses with the subscapular, a branch of the axillary. The cervicalis anterior or ascending cervical ascends upon the scalenus anticus, supplying it, the longus colli and the tectus capitis anticus major, and sending branches to th$ spinal cord and its membranes. The pro/undo, cervicis, or cervicalis posterior, arises from the upper and back part of the subclavian, on a level with and outside of the vertebral ; it ascends outward and back- ward between the transverse processes of the sixth and seventh cervical vertebrae, ascending on the back of the neck to supply the complexus and other deep muscles, and anas- tomosing with the descending branches of the occipital. This vessel is sometimes a branch of the superior intercostal. VEINS OF THE NECK, (Fig. 154.) The veins of the neck belong to the external jugular, internal jugular, anterior jugular, and subclavian veins. The external jugular begins at the angle of the lower jaw by the junction of the internal maxillary and temporal veins ; it then descends the neck, crossing the sterno-mas- toideus, covered by the platysma myoides and superficial cervical fascia. At the root of the neck it penetrates the deep cervical fascia behind the attachment of the sterno- mastoideus, and terminates in the subclavian on the out- side of the internal jugular. Its upper portion is accom- panied by the auricularis magnus nerve, one of the ascend- ing filaments of the cervical plexus. The branches which 508 BLOOD-VESSELS OF THE NECK. enter into the external jugular, besides the temporal and internal maxillary, are the occipital, posterior cervical FIG. 154. cutaneous, and the posterior and supra scapular reins, the last of which joins it at its termination. This vein communicates with the internal jugular, generally at its upper part, and in its descent with the anterior jugu- lar. It is, however, very varia- ble, being sometimes double and very small. It returns the blood from the external parts of the head, integuments and su- perficial muscles of the neck. The internal jugular vein is the great channel receiving the blood of the sinuses already noticed in the account of the brain. It commences at the foramen lacerum posterius, where the lateral sinuses ter- minate, then descends the neck first on the outside of and a little behind the internal carotid, then on the outside of the common carotid artery to the root of the neck, where it joins with the subclavian to form the vena innominata of each side — at its superior portion the ninth and eighth pair of nerves are on its inside, and the styloid process with its muscles are in front. The lingual and glosso-pharyngeal nerves are between this vein and the artery a little lower down, while the spinal accessory passes behind in its out- ward direction. The rest of the course of this vein is enclosed in the same sheath with the common carotid artery and pneumogastric nerve, receiving in its descent the facial, lingual, pharyngeal, and thyroid veins, and communicating freely with the external jugular. FIG. 154 represents the Veins of the Neck and Head, a Frontal vein. 6 Nasal vein, c Supra orbital, d Angular vein, e Facial vein. / Superfi- cial temporal veins, g Middle temporal, h Masseteric plexus of veins. i Occipital veins, j External jugular, k Internal jugular. I Anterior jugu- Jar m Scapular veins, n Subclavian vein, o Vena innominata. NERVES OF THE NECK. 509 The anterior jugular, called also superficial thyroid vein, begins at the os-hyoides, and descends along the anterior margin of the sterno-mastoideus, near the median line of the neck, covered by the superficial cervical fascia, and ter- minates below, either in the external jugular or subclavian veins. The two anterior jugulars often connect by a trans- verse branch and frequently communicate above with the facial, internal, and external jugular veins. They also vary much in size and return the blood from the superficial parts on the front of the neck. The subclavian veins are continuations of the axillary, anc}. are situated beneath the clavicle and subclavius mus- cle. Passing over the first rib, in front of the subclavian artery, and crossing the scalenus anticus muscle, they ter- minate by uniting with the internal jugular, to form the right and left vena innominata, which also unite to consti- tute the superior vena cava. The subclavian veins receive the tributary streams of the external jugular veins, the ver- tebral, inferior thyroid, inferior laryngeal, internal mammary, and superior intercostal — though these latter frequently empty into the vena innominata. SECTION V. These are the par vagum, spinal accessory, lingual, fa- cial, cervical plexus and phrenic nerve, brachial plexus, sympathetic nerve and its ganglia. The par vagum (Fig. 152) has been already fully de- scribed under the head of organs of deglutition in the neck, which see. The spinal accessory nerve, (Fig. 153,) or third division of the eighth pair, called the superior respiratory nerve of Sir Charles Bell, arises as low down in the neck as the fourth or fifth cervical vertebra, by several filaments from the res- piratory tract, between the anterior and posterior spinal roots; it ascends behind the ligamentum denticulatum, tp the base of the cranium, passes through the foramen mag- 510 NERVES OF THE NECK. num. and joins the other divisions of the eighth pair, along with which, and enclosed in the same sheath, it passes through the foramen lacerum posticus, and thence to the muscles on the side of the neck. In the foramen lacerum it is connected to the vagus by one or more filaments. On the outside of the foramen it divides itself into two branches — internal and external. The former is the smaller and joins the pneumogastric, while the external is the continuation of the accessory nerve, which proceeds outward, behind the internal jugular vein, to the sterno-mastoid muscle, the upper third of which it perforates and supplies with filaments, anastomosing with the second, third, and fourth cervical nerves, and finally being distributed upon the trapezius as low down as the scapula. The function of this nerve is regarded as purely motor, though the observations of Todd and Bowman assign sen- sation to the fibres of the internal branch. This nerve, along with the pneumogastric, has been compared to a com- pound or spinal nerve, the spinal accessory being the motor, while the vagus, with its ganglia, represents the sensory. TJie lingual, liypoglossal, or ninth pair of nerves, (Fig. 91.) This nerve is the motor nerve to the tongue, as well as to several structures at the superior part of the neck. It arises from the medulla oblongata between the corpus pyr- amidale and corpus olivare, by six or ten filaments, which, uniting together, pass out of the cranium through the an- terior condyloid foramen of the occipital bone. It then proceeds forward, between the internal jugular vein, and internal carotid artery, ascending with the vein as low as the angle of the jaw, when it curves across the occipital branch of the external carotid, taking the course of the digastric muscle and lingual artery, to the base of the tongue above the os-hyoides ; here it passes above the mylo-lm)ides, crossing the hyo-glossus, and dividing into filaments which supply these muscles, the genio-hyo-glos- sus and the lingualis, and continued forward through the tongue as far as its tip. NERVES OF THE NECK. 511 The branches of this nerve are, first, those which com- municate, on the outside of the condyloid foramen, with the pneumogastric, sympathetic, spinal accessory, and first and second cervical nerves. As it crosses the occipital artery it sends off the descendens-noni, which descends in front of and outside the sheath of the common caro- tid artery, to the middle of the neck, where it meets with branches from the second and third cervical nerves, forming a plexus which is distributed upon the sterno- hyoid, thyroid, and omo-hyoid muscles. About the os-hy- oides, filaments of the lingual have been traced to the constrictors of the pharynx, stylo-pharyngeus, and thyro- hyoid muscles ; and on the hyo-glossus, communicating branches form a plexus with the gustatory branch of the fifth pair. The facial nerve is described under the organs of expres- sion, to which the reader is referred. The cervical plexus (Fig. 153) is divided into the anterior B,nd. posterior cervical plexuses. The former is formed by the union of the anterior branches of the four superior cervical nerves, and is situated upon the side of the neck, between the trapezius and sterno-mastoid muscles, corresponding to the second, third, and fourth vertebra?, and covered by the platysma and fascia. This plexus rests upon the origin of the splenius and levator anguli scapulas muscles, and com- municates with the eighth and ninth nerves, and the su- perior cervical ganglion of the sympathetic. Its branches are divided into ascending and descending, and these again into superficial and deep. The superficial consist of — Superficialis colli, Auricu- laris magnus, and Occipital. The superficialis colli comes from the second and third cervical nerves, winds round the mastoid muscle, and as- cends, along with the external jugular vein, to the angle of the jaw. supplying filaments to the lower part of the face, and to the integuments of the lateral and anterior regions of the neck, and connecting with the cervico-facial. The auricularis magnus comes also from the second 512 NERVES OF THE NECK. and third cervical nerves, is larger than the last, and ascends hehind the mastoid muscle, to the parotid gland, where it divides into a superficial branch, supplying the integument over the parotid gland and anterior ear, and a deep one which enters the lower part of the gland, passes over the mastoid process, and is distributed to the back of the ear, and side and back of the scalp, and communicating with the facial and occipital nerves. The occipitalis minor arises from the second cervical, and proceeds upward, behind the mastoid muscle, to supply the skin of the back part of the head, and the occipital part of the occipito-frontalis muscle. The descending brandies of the cervical plexus are divided into superficial and deep. The former consist of external, middle, and internal branches, which, supply the integu- ments upon the sides of the neck, and extend down upon the pectoral and deltoid muscles. The deep descending branches consist of the muscular, the communicating, and the phrenic. The muscular supply the trapezius, levator anguli sea- pulse, and sterno-mastoid muscles, and come from different parts of the plexus. The communicating connect with the sympathetic, pneu- mo-gastric, and lingual nerves near the base of the cranium, and in front of the atlas. A nerve called the communicans noni, is a long, delicate branch, coming from the second and third cervical nerves, which descends generally in front of the sheath of the cer- vical vessels, though sometimes on the outside of the inter- nal jugular vein, and occasionally behind it, to the middle tendon of the omo-hyoid, where it unites in the form of a loop, with the descendens noni. The phrenic is a very important nerve, and is the internal respiratory of Sir Charles Bell. It arises from the third and fourth cervical nerves, with additional filaments from the fifth and sixth, and sometimes from the seventh, con- necting with the sympathetic. It descends in front of the scalenus anticus muscle, and at the root of the neck com- NERVES OF THE NECK. 613 municates with the inferior cervical ganglion, and fre- quently with the vagus and its recurrent branch ; at this point it enters the chest between the subclavian artery and vein, and proceeds downward on the side of the pericardium in the middle mediastinum, to the diaphragm, to which it is distributed, sending branches on the right side to the liver and vena cava, and on the left to the oesophagus and stomach. The left phrenic is longer than the right from the direction of the heart to the left side. It has been com- monly considered to be a purely motor nerve, but Laschka's recent researches show that it contains sensory filaments also. He states that it effects a double interchange between the spinal and the sympathetic nerves. It commonly arises only from the fourth cervical nerve. The diaphragmatic branches go to the tendinous centre, the inferior cava, the right auricle, and the liver. The posterior cervical plexus is formed by the junction of the posterior branches of the first, second and third cervical nerves. It is situated beneath the complexus. Its branches are called musculo-cutaneous and occipitalis major. The musculo cutaneous supplies the complexus and semi- spinalis colli, and then passes through the trapezius to become cutaneous, being distributed to the integuments on the back of the neck and head. The occipitalis major comes from the second cervical nerve, takes the course of the occipital artery, and supplies the muscles on the back part of the neck and head. The pos- terior branches of the lower cervical nerves supply the mus- cles and integuments on the lower and back part of the neck and head. The bracliial plexus (Fig. 153) is situated at the lower part of the neck in the posterior, inferior, lateral triangle, above the clavicle, and between the mastoid and posterior belly of the digastric muscles. It is formed by the union of the four inferior cervical and first dorsal nerves: the fifth and sixth unite into one trunk ; the eighth cervical and first dorsal also unite into one trunk ; the seventh cervical stands alone for some distance, so that this plexus presents 33 514 NERVES OF THE NECK. at first three roots, which again divide and unite in a variety of ways to constitute this plexus. Its lower part receives the name of axillary plexus. This plexus commu- nicates with the cervical by means of a filament from the fourth cervical nerve. In the neck it passes between the scalenus anticus and medius muscles, above and outside of the subclavian artery, under the clavicle and sub-cla- vian muscle, over ' the first rib to the axilla, where the branches of this plexus so interlace as completely to sur- round the axillary artery from the clavicle to the head of the humerus. The brachial plexus is very extensive, and sends branches to the neck, the anterior part of the chest, and the upper ex- tremity. Only those going to the neck claim our attention in this place. The balance of this plexus will be consid- ered in its appropriate relations with the organs of the chest and superior extremity. The branches supplying the neck are termed supra clavic- ular, and go to the subclavian muscle, the scaleni, levator anguli scapulae, and rhomboid muscles. The posterior thoracic, called also the external respiratory nerve of Mr. Bell, arises from the fourth, fifth and sixth cervical nerves, passes downward and outward, behind the brachial plexus and vessels, upon the scalenus posticus, and ultimately terminates in the great serratus muscle. This is a very long nerve, and from its origin so near the phrenic, its function, according to Bell, is to associate the serratus magnus muscle with the diaphragm in res- piration. Sympathetic nerve of the neck. — The sympathetic nerve is so called from its extensive relation with all the various parts of the body, connecting the several organs and vis- cera, and uniting the whole in one harmonious action or series of actions. It is also styled ganglionic, from the number of ganglia which occur upon it. By Bichat it was named the nervous system of organic life — in con- tradistinction to the cerebro-spinal or nervous system of animal life. Other terms, as the intercostal, splanchnic, NERVES OP THE NECK. 515 FIG. 155. and automatic, have all been applied to it. The sympathetic is not a single nerve, hut consists of two cords extend- ing from the hase of the cranium to the coccyx. Each of these cords de- scends along the neck anterior to the vertebras, behind the carotid artery and jugular vein, and in front of the rectus-capitis and longus colli muscles. In the chest they are traced along the sides of the spine, over the heads of the several ribs, and are found enter- ing the abdomen beneath the true lig- amentum arcuatum. They descend on the anterior part of the lumbar ver- tebras, between the psoas muscles and crura of the diaphragm, into the pel- vis ; they pass along the anterior sur- face of the sacrum to the first bone of the coccyx, where the two cords unite in a small ganglion, called coc- cygeal or ganglion impar. Throughout the whole course of these nerves a series of knots or ganglia are observed, named according to their situation, cervical, dorsal, lumbar, and sacral; there being three cervical, twelve dorsal, five lumbar, and three sacral. FIG. 155 represents the Sympathetic Nerve its entire length. 1 Superior cervical ganglion. 2 Its ascending branch. 3 Descending branch. 4 Exter- nal branches connecting with the first, second and third cervical nerves. 5 Internal branches connecting with the eighth, ninth and facial nerves. 6 Su- perior cardiac nerve. 7 Middle cardiac nerve. 8 Inferior cardiac nerve, coming successively from the first, second and third cervical ganglia. 9 First dorsal ganglion. 10 Last dorsal ganglion. 11 Spinal nerves. 12 Great splanchnic nerve. 13 Semilunar glangia forming the solar plexus. 14 Lesser splanchnic nerve, going to the renal plexus. 15 Branches from the lumbar ganglia. 16 Hypogastric plexus. 17 Sacral ganglia. 18 Ganglion impar or last ganglion of the sympathetic. 516 GANGLIA OF THE HEAD. From these ganglia an immense number of "branches radiate in every direction, constituting so many plexuses. The plexuses follow the course of the several arteries, re- ceiving the names of the respective vessels they pursue, aa the hepatic, gastric, splenic, renal, &c. In many in- stances they form complete nervous sheaths around the vessels. The sympathetic cords, it will be observed, in their de- scent along the spinal column, connect with all the spinal nerves by one or two filaments — with the cervical gene- rally by one, and with the dorsal, lumbar, and sacral by two. At their superior extremity they also communicate with all the cerebral nerves as they emerge from the cra- nium, except the fourth and sixth pair, and with these they unite in the cavernous sinus; while with the olfactory, optic, and auditory, the union occurs in their ultimate ex- pansion. There is also a communication of the sympathetic nerves with the several ganglia of the head, which gan- glia are regarded as the same with the rest of the gan- glionic system. And though they have been described along with the several organs of the head, yet for the pur- pose of having a connected view of the whole we introduce the following summary and figure (156.) Six sympathetic ganglia are found belonging to the head, as follows : The ganglion of Eibes, named after its discoverer, and situated upon the anterior communicating artery. This ganglion is the point of junction of the sympathetic cords of the opposite sides of the body, at their superior part. It sends filaments to the carotid plexus. The lenticular , ciliary or ophthalmic ganglion, is situated within the orbit, on the outside, and in close contact with the optic nerve, and imbedded in a quantity of fatty mat- ter. It is a small, flattened and grayish body, sending off the ciliary nerves to the eye, and, according to Tiedemann, a filament along with the arteria centralis retina. It communicates^with the nasal branch of the ophthalmic, with the third or motor oculi, and with the carotid plexus GANGLIA OF THE HEAD. 61T "by a long fil- ament going backward to the cavern- ous sinus. The spTie- no-palatine, or ganglion of Meckely is sit- uated in the spheno-max- illary fossa, in a quanti- ty of fat sur- rounded by branches of the internal maxillary artery, and presents a reddish triangular appearance. It gives off three sets of branches internal or nasal, descending or palatine, and pos- terior or Vidian — all of which have been described with the superior maxillary nerve, under the head of active organs of mastication. This ganglion of Meckel, by means of its Vidian nerve, which takes a most circuitous and lengthy route, as already described, establishes a communication with the carotid plexus, and through this latter with the superior cervical ganglion — with the glosso-pharyngeal and pneumogastric, by its tympanic branch, with the facial, superior, and inferior maxillary nerves, and with the sub- maxillary ganglion. The sub-maxillary ganglion is in contact with the sub- Fio. 156 represents the Cranial Ganglia of the Sympathetic Nerve, o Gan- glion of Ribes. 6 Filament connecting with the carotid plexus c. d Lenticu- lar ganglion e Third nerve getting a filament from the ganglion. / Nasal nerve also getting a filament from the ganglion, g A sympathetic filament going to carotid plexus, h Sixth nerve in cavernous sinus, getting two fila- ments from carotid plexus i Spheno-palatine or Meckel's ganglion, j Branches connecting with superior maxillary nerve, fc Palatine or descend- ing branches. I Spheno palatine or nasal branches, m Naso palatine, a branch of the latter, n Vidian or pterygoid nerve, o Its carotid branch, p Petrosal branch, q Facial nerve, r Chorda-tympani. s Gustatory nerve. I Submaxillary ganglion, u Superior cervical ganglion of the sympathetic. 518 GANGLIA OF THE HEAD. maxillary gland, is of small size, and communicates with the gustatory and lingual nerves, and with the sympa- thetic filaments of the facial artery, also, through the Vidian nerve, with the carotid plexus and the rest of the cranial ganglia. The otic-ganglion (or ganglion of Arnold) is found, directly below the foramen ovale, on the inside of the in- ferior maxillary nerve, upon the outside of the Eustachian tube, and anterior to the middle meningeal artery. It is a small, not very distinct, and reddish body, distributing filaments to the tensor palati and tensor tympani muscles, and communicating, by its branches, with both the motor and sentient portions of the inferior maxillary, and with the facial and tympanic branches of the glosso-pharyn- geal. The naso-palatine or ganglion of Cloquet. — The existence of this body as a proper ganglion has been doubted. It is very small, and when present, found in the foramen inci- sivum, distributing branches to the anterior palate, and communicating with the ganglion of Meckel, by means of the internal nasal branch passing off from this latter gang- lion and going to the ganglion of Cloquet. .Ganglion of Laumonier — (Fig. 157.) — This ganglion, named after its discoverer, is generally seen on the under surface of the carotid artery, within the carotid canal, though sometimes found in the cavernous sinus. It is small, and appears to be an expansion of the petrosal nerve before joining the carotid plexus, and is also called the ganglion caroticum, or cavernosum. It is represented as a flattened, elongated ganglion, form- ing the connecting link between the cranial and extra- cranial portions of the sympathetic. A variety of opinions are entertained as to the origin of the sympathetic. Some say it arises in the brain ; others, along the course of the spinal marrow, and its coccygeal extremity; while others, more recently, place its origin in the lining coat of the arteries. Those who assert its origin from the brain, say it is SYMPATHETIC NERVE. 519 by the union of the [Fio. 157. Vidian hranch of the fifth and sixth pair of nerves, whose di- verse properties com- ing together, consti- tute, as it were, a tertium quid, styled the sympathetic. This view is ex- plained by the ac- companying figure, from Lobstein. The latter opinion, which places the or- igin in the interior of the arteries, re- gards the lining coat of these vessels as essentially nervous, and makes the semi- lunar ganglion, in the abdomen, the great centre of this system. Whatever may be its origin, there is strong reason for believing, with Bichat, that it is the especial nerve or system of nerves for organic life, presiding over the functions of involuntary motion, as digestion, absorption, circulation, secretion — in a word, all the functions of nutrition. There are also FIG. 157 represents the origin of the Sympathetic Nerve, agreeably to Lob- stein, a a Carotid artery. 6 Ganglion of Laumonier. c From this latter ganglion three branches are sent off to join the sixth pair of nerves, d The sixth nerve separated into two fasciculi, e The superior fasciculus. / The inferior fasciculus parted, by a groove, from the superior; and it is the infe- rior which unites with the three branches from the ganglion, g Petrosal branch of Vidian nerve joining the ganglion, h Twig of the latter branch. i t Filaments proceeding from the ganglion to the artery, j A branch going behind the carotid from the ganglion, k A branch going from the ganglion in front of carotid, dividing it. I m Sympathetic nerve. w 520 SYMPATHETIC NERVE. reasons for believing it to be not only independent of the brain and spinal marrow, but the original and formative system to these latter portions as well as to the rest of the animal body.* Well authenticated cases are recorded of the absence of the brain, in acephalous foetuses ; and still further, of the whole cerebro-spinal system. But no cases, we believe,, are recorded of the sympathetic system being "wanting, which seems fairly to show independence, as well as priority of existence. The sympathetic, in the neck, presents three ganglia, the superior cervical, middle, and inferior cervical, (Fig. 155.) The superior cervical ganglion is situated upon the rec- tus capitis anticus, on the inside of the eighth and ninth pair of nerves, and behind the internal carotid artery and jugular vein. It is of an oval shape, and reddish color, ex* tending from the first cervical vertebra, about half an inch below the carotid foramen, to the third. Its branches are — superior, inferior, internal, external^ and anterior. The superior, two in number, ascend in the carotid canal, where they form the carotid plexus. Here a junction with the Vidian branch of the fifth and the sixth occurs, and from this point filaments are traced into the cavernous sinus, constituting the cavernous plexus, and from thence to the Casserian ganglion — also to the lentic- ular ganglion, while others are found accompanying the ophthalmic artery and its branches. The inferior branch forms the continued trunk of the sympathetic, which connects this with the middle or lower cervical ganglion. The internal branches proceed to the pharynx, larynx, and heart. Those of the pharynx unite with the glosso- pharyngeal and par vagum, forming the pharyngeal plexus. The laryngeal unite with the branches of the superior la- ryngeal nerve, while the cardiac descend the neck, behind the sheath of the common carotid, entering the chest, along * See appendix to Sir Wilson Philip on " acute and chronic diseases," by James H. Miller, M. D., former Professor of Anatomy in the Washington Medical College of Baltimore. GANGLIA OF THE NECK. 521 with the arteria innominata upon the right, and the sub- clavian artery upon the left side, to the great cardiac plexus. The external branches unite with the three superior cer- vical nerves, and with the lingual, par vagum, and glosso- pharyngeal. The anterior branches are called by Scarpa, nervi molles, from their soft texture. They are of a gray color, very numerous, and accompany the external carotid and its branches, forming plexuses around each, which are named according to the artery they surround, as the superior thyroid, facial, and lingual plexus. The middle cervical ganglion is situated upon the longus colli muscle, opposite the fifth cervical vertebra, and be- hind the common carotid artery, resting upon the superior thyroid artery. It is smaller than the superior, of irregu- lar form, and sometimes wanting. By Haller it is termed the thyroid ganglion. It sends off branches which ascend, descend, pass outward and inward, and communicate with the superior and inferior cervical ganglia, with the vagus, and fourth and fifth cervical nerves; it also sends down the middle or great cardiac nerve to join the cardiac plexus. The inferior cervical ganglion is situated between the neck of the first rib and the transverse process of the last cervical vertebra. Instead of being single, it sometimes consists of several ganglia, behind and on either side of the vertebral artery. It also radiates branches in every direc- tion. The superior conneqt with the middle cervical gang- lion, and a considerable number ascend along with the vertebral artery, forming plexuses around it, and entering the cranium to connect with the carotid plexus. Its external branches unite with the three lower cervical and first dorsal nerves. Its inferior go before and behind the subclavian artery to unite with the first thoracic ganglia, and from its interior, the inferior cardiac nerve descends to the cardiac plexus, connecting with the vagus and recurrent. Fila- ments also pass from the inferior cervical ganglion to the 522 FASCIA OF THE NECK. phrenic nerve and brachial plexus. The rest of the sym- pathetic will be examined in connection with the abdomi- nal and thoracic organs. SECTION VI. THE FASCLE OF THE NECK. — (CERVICAL FASCLE.) The fasciae of the neck are divided into the superficial and deep cervical. The superficial cervical fascia is situated immediately beneath the integuments, enclosing the platysma myoides, and sometimes so closely connected to this muscle, as to be with difficulty separated from it. It is continuous with the superficial fascia of the abdomen and chest, and attached to the sternum and clavicle. It is traced over the lateral and anterior parts of the neck, ascending to the jaw with which it is connected, and expanding over the parotid and sub-maxillary glands, it sends processes into the sub- stance which surrounds their several lobules. It then pro- ceeds upward to form a strong attachment to the cartilage of the ear, mastoid process, and zygoma. It forms the an- terior layer of the sterno-mastoid, becomes weak at the lateral and posterior portions of the neck, gives a covering in front and behind to the trapezius, and is traced into the fascia profunda or deep cervical fascia. Indeed, this latter fascia is regarded as nothing more than the reflected portion of the deep surface of the superficial cervical, and, so considered, it is found to pass from the su- perficial along the anterior margin of the sterno-mastoid, go- ing behind this muscle, the omo-hyoid and trapezius, back to the ligamentum nuchae, which some regard as its origin. In front it is connected to the larynx and thyroid gland, invests the sterno-hyoid and sterno-thyroid muscles, forms sheaths for the other muscles, as well for the vessels and nerves, and at the inferior part of the neck is attached to the inter-clavicular ligament and upper posterior margin of the sternum, adjacent to the clavicle and first rib. At this point, the root of the neck, some loose fatty matter is GLANDS OF THE NECK. 523 found between the superficial and deep cervical fascia. Between the trapezius and sterno-mastoid, the deep cervical fascia presents the cellular appearance. At the angle and base of the jaw to which it is connected, it dips down deep to be attached to the styloid process, forming the stylo- maxillary ligament, and the partition between the parotid and sub-maxillary glands. At this superior part we find the two cervical fascise enclosing the parotid, absorbent glands, and considerable cellular structure. Hence, when inflammation is set up, and matter is formed, from the un- yielding and resisting nature of these fasciae, the suffering is increased, and the function of deglutition, together with the movements of the jaw materially interrupted. The uses of the cervical fasciae are to confine and support the several muscles, vessels, and glands ; and at the lower part of the neck, according to the experiments of Mr. Law- rence, to protect the trachea from the pressure of the atmos- phere during inspiration. Lymphatic Glands of the Neck, (cervical glands) — The lymphatic glands belong to the conglobate division, and form part of the absorbent system. This system performs the function of absorption, and consists of the lacteals, lym- phatic vessels, and lymphatic glands. The glands have already been summarily described under the head of the glandular tissue. It is only necessary for us here, there- fore, briefly to recapitulate the lymphatic or cervical glands of the neck. These are divided into the superficial and deep. The former are seen along the posterior margin of the sterno- cleido-mastoideus, lying scattered between this muscle and the trapezius, and in connection with the external jugu- lar vein. The deep glands are large and numerous and form a chain descending tbe neck, in company with the carotid vessels, from the angle of the jaw to the chest. They are also connected with the pharynx, oesophagus, larynx, and thyroid gland, and with the glands of the face above and the thorax below. Through both the superficial and deep get of glands, the lymphatics of the head and neck pass. 624 GLANDS OF THE NECK. Thyroid Gland. — This gland is situated upon the sides of the larynx and upper rings of the trachea. It is large, and consists of two portions lying laterally, and connected across the upper part of the trachea by a middle portion called the isthmus. The lateral parts are termed lobes. This gland is of a reddish brown color, deeper in the child than in the adult, and in the female than the male. Its consistence is soft. ••>'$' ' The lobes are prominent and convex, being covered by the sterno-hyoid, thyroid, and omo-hyoid muscles, pla- tysma, fascia, and skin, tying along the side of the trachea and larynx, ascending as high as the thyroid cartilage, and connected occasionally to the base of the os-hyoides, by a slip which is thought to be muscular, and called by Soemmering levator-glandulce, though its muscular char- acter is doubted by others. Upon the left side, the lobe rests upon the oesophagus, both right and left lobes cover the carotid artery, inferior thyroid vessels, and recurrent nerve on either side of the neck. The isthmus or middle lobe is sometimes wanting; at other times, instead of passing in front of the trachea, it goes behind it, • and then rests upon the oasophagus. In this case, should there be enlargement, not only embarrass- ment, but considerable danger to both respiration and deglutition might be the result. The thyroid gland consists of lobules, which are again divisible into cells, containing a yellow serous and oily fluid, according to some; and a viscid, transparent secre- tion, according to others. This body has no proper capsule, unless the cellular tissue surrounding it be regarded as such. It has no excretory duct, and, though called a gland, can have no claim to such title in the proper sense of the term. It is largely supplied with blood-vessels. The two supe- rior thyroid arteries from the external carotid, go to it from above, and the two inferior thyroid from the subclavian below. The corresponding veins are distinguished for their size and number. THE LARYNX. 525 The nerves come from the sympathetic and pneumo- gastric. The lymphatics pass into the cervical glands. The thyroid, in the infant, descends as low as the thy- mus gland. It not unfrequently suffers enlargement con- stituting the disease called goitre, or bronchocele. Its function is yet unsettled, though it is regarded as a diverticulum to the cerebral circulation. SECTION VII. THE LARYNX, OR ORGAN OF VOICE. The larynx is situated at the anterior part of the neck, between the tongue and trachea, surmounting the respi- ratory tube, and thus being connected with the organs of respiration below, as well as with the pharynx or that of deglutition above. It consists of cartilages, ligaments, mus- cles, vocal chords, a lining mucous membrane and glands, with blood-vessels, and nerves — thus forming a great vari- ety of structures, and an apparatus both curious and com- plicated. Cartilages. — The cartilages form the solid frame work, and constitute the basis of 'the larynx. They are five in num- ber, the thyroid, cricoid, two arytenoid, and p,Gt 153. epiglottis. These, united, form the larynx, a hollow box or musical case, whose cav- ity is somewhat quadrangular and larger above than below. The thyroid (0vp«oj, shield, «&>$, like) is the largest of the cartilages, and occupies the anterior and lateral portions of the larynx. It consists of two sym- metrical parts called alee, which meet in front along the median line, in an acute angle forming a prominence, known under the name of pomum Adami. Each ala pre- sents a broad quadrilateral plate which looks backward, and on its posterior margin, at the superior and inferior FIG. 158 represents the Thyroid Cartilage, a Superior cornu. c Inferior cornu. 6 Ala of left side, d Entering angle. 526 THE LARYNX. extremity has two tubercles, termed the superior and infe- rior cornua. Each ala has an oblique line, dividing it into two unequal parts, and giving attachment to the sterno- thyroid, thyro-hyoid, and inferior constrictor muscles of the pharynx. The superior cornua are connected by liga- ments to the os-hyoides — the inferior are articulated with the cricoid. The thyroid is open behind, and encloses the sides of the cricoid. Its posterior surface, behind the pomum, is concave and has attached to it the chordas-vocales, and epiglottic ligament. The cricoid, (*p«coj, ring, «So^ like,) as its name implies, is annular or ring-like in its form ; it is situated at the lower and posterior portion of the larynx, giving that pro- tection from the pressure of the parts behind, which the thyroid does from that of the atmosphere in front. It is narrow before, and broad and vertical behind. Its anterior surface is convex, and has the crico-thyroid mus- FIG 159. cles attached to it. The posterior surface pre- sents a depression for the crico-arytenoidei postici, and along its middle, a vertical ridge giving attachment to some fibres of the oeso- phagus. The upper margin is horizontal, and has two convex, smooth surfaces, for articulation with the bases of the arytenoid cartilages. The lower margin is circular, and connected to the first ring of the trachea. The arytenoid cartilages (apv^a^a, a pitcher) occupy a ver- FIG. 160. tical position upon the upper and posterior part of the cricoid. They are of a triangular shape, and are two in number. They are the smallest in size, and present an anterior sur- face, which is convex and rough, and gives attachment to the chordaz-vocales ; a posterior surface, which is con- cave, for the reception of the arytenoid -muscle ; an inter- nal surface, which is flat, smooth, and covered by mucous membrane, where the two arytenoids approximate ; an FIG. 159 represents the Cricoid Cartilage. FIG. 160 represents the two Arytenoid Cartilages. THE LARYNX. 527 • inferior surface, which is also smooth, but convex, constitu- ting the base, and articulating with the cricoid ; and an upper extremity, or apex, which is surmounted by a small movable body, called the appendix, or corniculum laryngis, also styled tuberculum Santorini. The epiglottis— (e *v{wt tj, upon the tongue.) — This cartilage is situated at the base of the tongue, and is a fibro-cartila- ginous structure. It occupies nearly a vertical position at the back part of the mouth. Its form is oval FlG- 161» and flattened, having its edges curved. It is of a yellowish color, pliable and elastic. Its surfaces are anterior and posterior, or lingual and laryn- geal. Both surfaces, as well as the edges, are covered by mucous membrane, which, in front, is loose, and constitutes a fold called the fre. num epiglottidis. On the laryngeal surface this membrane is strongly attached, and presents the orifices of mucous ducts, and when removed shows the cartilage itself to be perforated. It differs from the other cartilages in never being found ossi- fied. It is so nicely adapted to the superior opening of the larynx, as completely to close the glottis in deglutition, and thereby guard against the introduction of foreign bodies, and consequently against suffocation in the act of respiration. Ligaments. — The ligaments, connecting the thyroid car- tilage with the os-hyoides, are three in number — a middle, the ihyro-liyoid membrane, which occupies the whole space, extending from the superior edge of the thyroid cartilage, to the base and cornua of the os-hyoides ; and two lateral, the thyro-hyoid, extending from the superior cornua of the thyroid cartilage, to the extremities of the cornua of the os-hyoides. The middle ligament is a strong fibrous expan- sion, giving passage to the superior laryngeal nerve and artery. The lateral consist of round cords sometimes con- taining cartilaginous or osseous grains. FIG. 161 represents a side view of the Epiglottis Cartilage, a Front of lingual surface. & Posterior or pharyngeal surface, c Upper margin, d Lower margin or pedicle, e Lateral portion. 528 THE LARYNX. « The ligaments connecting the thyroid to the cricoid are also three in number, a middle and two lateral. The middle crico-thyroid is a strong, yellow, and mem- branous ligament attached above to the lower edge of the thyroid, and below into the upper edge of the cricoid car- tilage. This ligament gives passage to some small blood- vessels, and is interesting from being the place of selection for the operation of laryngotomy. The lateral crico thyroid ligaments consist of the capsular and synovial membranes, forming articulations between the inferior cornua of the thyroid cartilage and the sides of the cricoid. The arytenoid cartilages have two sets of ligaments — the one connecting them with the cricoid, called the crico- arytenoid — the other with the thyroid, termed the thyro- arytenoid ligaments. The first set consists of two capsular ligaments and synovial membranes, by which the base of the arytenoid cartilages articulate with the superior mar- gin of the cricoid. This articulation allows a great free- dom of motion. The second set comprises four ligaments, two superior, and two inferior. The former are sometimes called false ligaments, as they consist of little else than folds of mucous membrane, containing some delicate fasciculi of elastic fibres, which extend from the inner angle of the thyroid to the anterior face of the arytenoid. The inferior thyro-arytenoid ligaments are true fibrous chords, and constitute the chordce vocales. They extend from the inner angle of the thyroid, horizontally back- ward to the base of the arytenoid cartilage. These liga- ments are strong, and consist of elastic and parallel fibres which are associated with the thyro-arytenoid muscles, and pursue the same direction. The space between these infe- rior ligaments is the glottis or rima-glottidis. There are two proper ligaments of the epiglottis, the ihyro-epiglottideus and the liyo-epiglottideus. The former extends as a strong chord from the epiglottis to the inner margin of the thyroid notch; the latter is seen as a thin elastic membrane situated below the base of the os-hyoides MUSCLES OF THE LARYNX. 529 and the front of the epiglottis. The folds of mucous mem- brane connecting the epiglottis to the base of the tongue, have also been called ligaments — they are three in num- ber. The middle one, called the frenum epiglottidis , has a few elastic fibres and some cellular tissue. Muscles of the Larynx. — The muscles of the larynx are nine in number, eight of which are in pairs. Dissection. — Make the same in- FIG. 162. cisions as for the anterior neck, and remove the platysma, fascia, and sterno-hyoideus, and sterno- thyroideus muscles. We thus ex- pose the anterior muscles of the larynx — which are the thyro-hy- bideus and crico-thyroideus. The tliyro-liyoideus (Fig. 162) is a broad, flat muscle, and looks very much like a continuation of the sterno-thyroideus. It arises from the oblique line on the ala of the thyroid cartilage, ascends, and is in- a' serted into the lower margin of the corrm of the os-hyoides and part of its base. Its function is to raise the larynx, or when the latter is fixed to draw down the os-hyoides. The crico-thyroideus (Fig. 162) is a short muscle, lying below the last. It arises from the anterior surface of the cricoid cartilage; its fibres pass outward and upward, to be inserted into the inferior mar- gin arid cornu of the thyroid. function. — To bring these two cartilages towards each other, and thus shorten the vocal case. On the lateral and posterior portions of the larynx we have the tliyro~arytenoideus,,crico-arytenoideus posticus, crico- arytenoideus lateralis, arytenoideus obliquus, arytenoideus FIG. 162 represents the Muscles in front of the Larynx, a Sterno thy- roideus. 6 Crico-thyroideus. c Thyro-hyoideus. d Mylo-h\oideus. 31 530 MUSCLES OF THE LARYNX. transversus. To which are also added the ihyro-epiglotti- deuSj aryteno-epiglottideus. The thyro-arytenoideus, within the vocal case, arises near the angle of the thyroid cartilage on its posterior sur- FIG. 163. face, and proceeds backward and out- ward, along the sides of the rima glot- tidis, to be inserted into the anterior and outer margin of the arytenoid car- tilage. Function. — To bring the ary- tenoid cartilages forward, and thus relax the vocal chords. These muscles are regarded as the most important in the production of voice. They are con- cealed by the alee of the thyroid car- tilage, and are connected with and run along the vocal ligaments. Crico-arytenoideus posticus. — Dissection. — Open the pha- rynx by a vertical incision and dissect off the mucous membrane. FIG. 164. This muscle will then be seen to arise from the posterior surface of the cricoid cartilage, and to pass obliquely upward and outward, as a flat and strong muscle, to be inserted into the posterior and outer part of the base of the arytenoid cartilage. Function. — To antagonize the pre- ceding muscle by drawing backward the arytenoid cartilages and making tense the vocal chords. The crico-arytenoideus lateralis — (Fig. 163) arises from the side of the cricoid at its upper F,G. 163 represents two of the Muscles of the Larynx, a Epiglottis. 6 Cri- coid cartilage, c Thyroid cartilage, d Crico-arytenoideus lateralis mus t Thyro-arytenoideus. FIG 164 represents the Muscles on the posterior Larynx, a Epiglottis. 6 Thyroid cartilage, c Cricoid cartilage, d Crico-arytenoideus-posticus. * Arytenoideus transversus. / Arytenoideus obliquus. MUSCLES OF THE LARYNX. 531 edge, runs obliquely upward and backward, and is in- serted into the base of the arytenoid. Function. — To draw the arytenoids outward, and enlarge the rima glottidis, as in inspiration. This is a dilator muscle. Arytenoideus obliquus (Fig. 164J arises from the base of one arytenoid cartilage, and is inserted into the apex of the other. Its fibres are small and sometimes absent, and it is described by some anatomists as forming a part of the next muscle. The arytenoideus transversus (Fig. 164) arises from the posterior surface of the one arytenoid cartilage, and runs transversely to be, inserted at a similar point on the other, and filling up the concavities of each. This is a single muscle. Function. — Both these latter muscles bring the aryte- noids together, and thus close the glottis, being thereby constrictors of this opening. The tliyro-epiglottideus has indistinct fibres, which arise from the inner angle of the thyroid cartilage, and are inserted into the base and side of the epiglottis. Function. — To draw down the epiglottis. Aryteno-epiglottideus. — The fibres of this muscle are also indistinct. It arises from the superior extremities of the arytenoid cartilages, and passes forward and upward to be inserted into the sides of the epiglottis. Function. — The same as the latter muscle. An inferior aryteno-epiglottidean muscle is spoken of by Mr. Hilton, as arising from the arytenoid cartilage above the vocal chords, and thence proceeding forward, over the sacculus laryngis, to be inserted into the side of the epiglot- tis. Its use, he thinks, is to diminish the cavity of this sac, and compress the adjacent mucous glands. The conjoint action of all these muscles tends harmoni- ously to one common end — the production of voice ; and although, to a considerable extent, they are voluntary, nevertheless the will has not perfect command over their separate actions; and, says Mr. Harrison, "those fibres which are connected with the epiglottis, and which proba- 532 MUCOUS MEMBRANE OF THE LARYNX. bly minister to the function of deglutition, rather than to that of voice, appear wholly from under the influence of the will, and act in that spasmodic or convulsive motion by which the food is hurried over the glottis, and precipi- tated into the oesophagus." MUCOUS MEMBRANE OF THE LARYNX AND GLANDS. The mucous membrane of the larynx is a continuation of that lining the mouth, nose, and pharynx. It is of a pink- ish color, smooth and soft, and proceeds from the base of the tongue to the anterior surface of the epiglottis, in three folds, the middle one being the frcenum. From this it passes round upon the posterior surface of the epiglottis, where it adheres pretty strongly ; from this it is reflected backward to the arytenoid cartilages, constituting the ary- teno-epiglottic folds, or, according to some, the superior or false vocal ligaments. Here it becomes continuous with the mucous membrane of the pharynx, and covers the pos- terior surface of the larynx. From the upper ligaments it descends within the larynx, to the inferior or true chordae vocales, lining the intervening space, called the ventricle of Morgagni, and also an offset from this ventricle, termed the sacculus laryngis. It adheres to both these cavities loosely. Upon the inferior vocal chords it is very thin and adheres strongly, is traced downward, lining every de- pression and eminence, and is continuous with that found in the trachea, bronchial tubes, and air-cells of the lungs. This membrane is perforated by a multitude of foramina, the orifices of mucous ducts. Sixty or seventy are said to belong to the sacculus laryngis. Its epithelium is found to be of the columnar form and ciliated. The cilife direct the secretion upward, and, according to Henle, are found extending higher up in front than upon the sides or be- hind. In front they reach to the posterior surface of the epiglottis, and upon the sides as high as the superior ligaments, beyond which the epithelium takes the lami- nated form of the pharynx and mouth. The upper portion of this membrane has great sensibility. KELATIONS OF THE LARYNX. 533 The glands of the larynx are distinguished into the epi- glottic and arytenoid. The former are nothing more than a mass of fatty matter situated between the epiglottis and thyro-hyoid membrane. The only epiglottic glands, says Cruveilhier, belonging to the epiglottis are found within its substance, which is perforated with innumerable orifices for their reception. All of these ducts open upon the laryn- geal surface and furnish a considerable quantity of mucus. The arytenoid glands are found in the aryteno-epi glottic folds of mucous membrane, and must not be confounded with some little cuneiform cartilaginous bodies also seen in this situation. Blood-vessels. — The arteries supplying the larynx are four in number, the two superior, and two inferior thyroid. The former come from the external carotid — the latter from the subclavian. The veins accompanying the arte- ries terminate in the adjoining venous trunks. Nerves. — The nerves (Fig. 152) supplying the larynx are four in number, and all come from the pneumo-gastric or par vagum. Two are above, arise near the base of the cranium, and are called the superior laryngeal. The other two are below, arise from the par vagum at the root of the neck, and are called the inferior laryngeal, or recur- rent nerves. The former chiefly supply the mucous mem- brane of the larynx, and are mostly nerves of sensation. The latter go principally to the muscles, and are mostly nerves of motion. For a more minute description of the blood-vessels and nerves of the larynx, see the circulation and nerves of the neck. Relations of the Larynx. — The relations of the human larynx are three-fold, physical^ mental and organic. The physical are those which the larynx has with atmospheric air in the production of voice. The mental are those con- nected with the cerebrum, as the representative and instru- ment of the mind, and are concerned in the intellectual functions of language and oratory; while the organic refer more particularly to the relations of the larynx with all the other organs of the body. By means of the pneumogas- 534: THE TRACHEA. trie nerve, a most extensive organic connection, as already shown, is maintained between the organ of voice and the functions of digestion, respiration and circulation, through the agency of the laryngeal, pharyngeal, cardiac, pulmo- nary, cesophageal, and gastric branches of this pneumo- gastric nerve, associated with the great sympathetic of the neck, chest, and abdomen. But the most important rela- tion of the larynx to the dentist is that which it has with the mouth. Here the anatomical and physiological relationship is most close and important. The same mucous membrane extends from the one cavity into the other — from the mouth into the larynx. Blood-vessels and nerves, from the same sources also associate the two sets of organs, and lesion or destruction of the one, not only cripples and de- stroys its own functions, but also extends in greater or less degree to those of the other. For example, the loss of teeth, a cleft palate, swollen tonsils, hare-lip, &c., illus- trate the injury inflicted upon the voice as well as the speech, in the subversion of the natural relations of the mouth and larynx, by this structural change in the organs belonging to the mouth. The same result would follow should the larynx be altered from its natural condition by change in any of its parts. Trachea — (Vpa^ss rough.) — The trachea (or arteria as- pera) is situated upon the median line of the neck, between the larynx above, to which it is connected, and the bron- chia below into which it divides. It commences about the fifth cervical vertebra below the larynx, and descends in front of the oesophagus and vertebral column, into the chest, behind the arch of the aorta, and in front of the third dorsal vertebra, where it terminates, dividing into the right and left bronchi, which go to the lungs. Its length and diameter vary according to age and sex, but the average in the adult is about five inches in length, and from three- quarters to one inch in diameter. The structure of the trachea consists of cartilage, fibrous THE TRACHEA. 635 and elastic tissue, mucous membrane and glands, with muscular ^fibres. The cartilage, FIG. 165. thin, flexible, read- ily compressed, but very elastic, as- sumes the form of flattened rings. — These rings, how- ever, are not com- plete, being defi- cient in their poste- rior part, and form- ing only about three-fourths of a circle. They resem- ble in structure that of the nose and external ear more than those of the la- rynx. The rings run transversely, being placed one above the other, and averaging in number about eighteen. Each ring is convex externally and concave internally, enclosed within the fibrous, and lined by the mucous membrane. These cartilages preserve the trachea as a permanently open tube for the free ingress and egress of the air. Each ring is about two lines wide, an inch and a half in length, and a line in depth ; their upper and lower edges are thin, and their extremities blunted. Their size is irregular, being sometimes larger in one part than another, and not always parallel. The lower cartilages are occasionally bifid, resembling those of the bronchi. The fibrous tissue is regarded as the fundamental part, forming the continued tube of the trachea, being at- FIG. 165 represents the'Trachea and Bronchi. 1 Thyroid cartilage. 2 Cricoid cartilage. 3 3 Trachea. 4 Left bronchus. 5 Right bronchus. 536 THE TRACHEA. tached above to the larynx, and continued below into the bronchi. It has the cartilaginous portion deposited in it, and forms a sheath for each particular ring, and supplying the deficiency behind, where the rings cease. This tissue is regarded as belonging to the yellow elastic, and restores the trachea, when elongated, to its natural length. The elastic tissue presents the form of longitudinal bands, is found between the mucous and muscular coats, at the posterior portion of the trachea, and descends into the bronchi. The muscular fibres are attached to the ends of the cartilaginous rings behind — fill up their deficiency, are about half a line in thickness, and run transversely. They are exposed by dissecting off the fibrous coat, when they are seen to be thin and pale. Their function is to diminish the size of the trachea, and assist in expelling the mucus during expiration. The mucous membrane extends from the larynx, lines the trachea, and is traced downward through the bronchial tubes in all their ramifications, as far as the air-cells of the lungs. This membrane is thin, delicate, and pale, and presents numerous foramina, the orifices of mucous glands. These glands are found most abundantly on the posterior surface of the trachea, situated in the muscular coat, be- tween the muscular and fibrous, in the substance of th'e fibrous, and between the latter and the mucous. They mostly present the form of small ovoid bodies, but have occasionally attained a much larger size. The blood-vessels supplying the trachea come principally from the superior and inferior thyroid arteries. The veins are superficial and deep, and enter the adjoining veins. The nerves come from the par vagum. THE ABDOMEN. 537 CHAPTER III. ACTIVE ORGANS OF THE TRUNK. SECOND DIVISION. ORGANS OF THE ABDOMEN. THE active organs of the trunk comprise, in the physio- logical order, most of the organs of the abdomen, which are divided into organs of digestion, and organs of absorption. GENERAL OBSERVATIONS UPON THE ABDOMEN. The abdomen (abdo, to hide) is situated between the chest and pelvis, and is the largest cavity in the body. It is bounded, anteriorly and laterally, by the abdominal muscles and fascia — posteriorly by the quadrati lumborum, psoa3 muscles, crura of the diaphragm, and lumbar verte- brae— superiorly by the diaphragm, and inferiorly by the pelvis. This cavity contains a variety of organs, called viscera, which, for the purpose of localizing them, as well as for the convenience of description, have determined anato- mists to divide the abdomen into regions, (Fig. 166.) By drawing two transverse lines across the abdomen, the one superior at the lower margin of the true ribs, the other inferior from the crista of the ilium on the one side to the same point on the opposite — then bisecting these at right angles by two vertical lines, one upon either side, and bringing them from the middle of Poupart's ligament to the cartilage of the eighth rib, then taking the anterior circum- ference of the abdomen, we have marked off nine regions. Three of these occupy the middle line, and three are upon either side. The superior median region is called the epigastric, the central, the umbilical, the inferior middle,- the hypogastric region. Those upon the sides are the right and left hypochondriac, upon eacli side of the epigastric; the right and left lumbar, upon each side of the umbilical ; and the right and left iliac, upon each side of the hypo- 538 REGIONS OF THE ABDOMEN. gastric region. Two other regions are spoken of— the FlG> 166< one about the ensiform cartilage, called the scro- liculus-cordis — and the other about the symphy- sis pubis, called the re- gio pubis. These several regions are more or less arbitrary, and the dis- sector will soon find that nature does not confine herself to the limits here prescribed. The epigastric region (frtc, over, yasT'jfp, stomach) contains most of the sto- mach, the solar plexus of nerves, the pancreas, left lobe of the liver, left extremity of the right lobe, and is traversed in the longitudinal direction by the aorta, thoracic duct, and commencement of the vena azygos. The umbilical region surrounds the navel, and contains the upper portions of the small intestines, mesentery, and arch of the colon, covered by the omentum majus. The hypogastric (vrto, under, ya^p, stomach,) contains the lower portion of the small intestines, the termination of the aorta, and commencement of the vena-cava ascendens. The hypochondriac, (Wo, under, xov8po$, cartilage,) right and left, are on either side of the epigastric and beneath FIG. 166 represents the Regions of the Abdomen. 1 1 A line drawn from the crest of the ilium on the one side, to the same point on the opposite side. 5 2, 3 3 Lines drawn perpendicularly from the anterior inferior spinous pro- cesses, to the cartilages of the ribs. 4 4 A line parallel to 1 1 and passing along the xiphoid, and most prominent costal cartilages. 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 Pubic region. WALLS OF THE ABDOMEN. 539 the cartilages. The right contains the right lobe of the liver; portion of the duodenum, and colon. The left con- tains the spleen, the left extremity of the stomach, part of the left extremity of the liver, and left end of the pancreas. The lumbar regions, upon each side of the umbilical, con- tain the right and left kidneys, with the ascending and descending portions of the colon. The iliac are on each side of the hypogastric ; the right contains the termination of the ilium, and commencement of the colon, or caput-coli — the left has the termination of the colon, called the sigmoid flexure. The lower portions of the iliac regions receive the names also of inguinal or spermatic. ^ SECTION I. WALLS OF THE ABDOMEN. The anterior and lateral walls are composed chiefly of muscles and fascia. Dissection. — Make an incision from the symphysis pubis, to the end of the second bone of the sternum. From this latter point, carry a second incision obliquely downward and outward towards the arm-pit, and onward to the spine. A third incision, commencing on the second, about the middle of the chest, and carried downward and inward towards the spine of the pubis, will be in the direction of the fibres of the superficial or external oblique muscle, at the upper part of which line the dissection should commence. The muscles are five pair — three broad, and two narrow. The broad are the external oblique, internal oblique, and transversalis ; the narrow are the rectus abdominis, and pyramidalis. The external oblique muscle, (obliquus externus abdominis descendens) so named from the direction of its fibres, is the most superficial of all the abdominal muscles, and the largest. It is thin and broad, and arises, by fleshy and tendinous digitations, from the eight or nine inferior ribs, at their lower edges and anterior surfaces, near the car- 540 MUSCLES OF THE ABDOMEN". tilages. The five superior heads interlock with the ser- Fio. 167. ratus major anticus ; the three inferior with the latis- simus-dorsi, by which lat- ter it is a lit- tle overlapped. The fibres of the first head blend with, and are fre- quently cov- ered by a slip from the pec- tor alis major. At the supe- rior part this muscle ap- pears thin and aponeu- rotic, and so weak as to be not unfrequently removed, without great care in dissection. It descends in a broad, thin, aponeuro- tic tendon, which meets its fellow the whole extent of the linea alba, and the two together cover the whole front surface of the abdomen. The posterior and lateral portions are muscular. It is inserted into the linea alba, where it joins its fellow, into the ensiform cartilage, tendinous and FIG. 167 represents the superficial Muscles of the anterior walls of the Abdo- men. 1 Pectoralis major. 2 Deltoid. 3 Latissimus dorsi. 4 Serratus- major-anticus. 5 Subclavius. 6 Pectoralis minor. 7 Coraco-brachialis. 8 Biceps flexor cubiti. 9 Coracoid process of scapula. 10 Serratus major anticus, after removing external oblique. 11 External intercostal muscle. 12 External oblique. 13 Its tendon. 14 Poupart's ligament. 15 External abdominal ring. 16 Rectus-abdominis. 17 Pyramidalis. 18 Internal ob- lique. 19 Common tendon of internal oblique and transversalis. 20 Crural arch. 21 Fascia lata. 22 Saphenous opening. MUSCLES OF THE ABDOMEN. 541 fleshy into the anterior half of the crest of the ilium at its outer edge, and from the anterior superior spinous process of the ilium it descends in the form of a cord under the name ofPoupart's ligament, (which ligament is regarded simply as a folding or reflection of the lower margin of this muscle,) to the spine and front of the puhis, and thence along the pectineal line forming Gimbernat's ligament. When the two external oblique muscles are neatly exposed the following points are noticed, the linea-alba, umbilicus^ FIG. 168. lineae semilunareSjlineas transver- se, and the external abdominal or inguinal ring. The linea alba ex- tends from the ensiform cartilage, along the median line to the sym- physis puhis. It is formed by the common union of the tendons of the oblique and transverse mus- cles of opposite sides, which pre- sent the form of a strong ligament- ous band, whose greatest width and thickness is at the umbilicus. The umbilicus is situated at or a little below the centre of the linea alba. It is called the navel, and in the fcetus is a foramen through which pass the umbilical vein, arteries, and urachus. These several parts in the adult become ligamentous cords, being no longer open vessels, which, with the cellular tis- sue that surrounds and connects them together, and to the tendinous margin of the foramen, fill up this opening. The integument mostly containing fat in the adult, presents at the umbilicus a depression. Umbilical hernia occasionally occurs at this place. The linece semilunares are two white FIG. 168 represents right Inguinal Hernia, a Inferior portion of aponeurotic tendon of external oblique, b Poupart's ligament, c Anterior superior spinous process, d Spine of pubis. e External abdominal ring. / Upper column of the ring, g Lower column of the ring, h Semilunar fibres of curved shape, and designed to strengthen the ring, i Iliac portion of fascia lata. j Pubic portion, k Saphenic opening. I Falciform edge. 542 MUSCLES OF THE ABDOMEN. ovally-curved lines upon each side, and about three Inches distant from the linea alba, formed by the splitting of the tendon of the internal oblique, where it proceeds to form a sheath for the rectus muscle. The linece transversce are three or four short lines, going from the linea alba transversely across the rectus muscle, to the lineae semilunares ; one of these lines is seen at the umbilicus, another at the lower end of the ensiform cartilage, a third between these two points, and sometimes a fourth midway the navel and pubis. The external abdominal ring (Fig. 168) is situated in the lower part of the tendon of the external oblique, superior and external to the spine of the pubis upon each side, above Poupart's ligament. This ring (improperly so called)- is triangular in form, having its base toward the pubis, and its apex external and superior. The sides of this opening are termed columns or pillars, superior and inferior. The superior column is broad, and its fibres go to the sym- physis pubis, and decussate with those of its fellow in front of the pubis and dorsum of the penis. The inferior column, called also the pubic end of Poupart's ligament, or third insertion of the external oblique, goes to the spine of the pubis and about an inch along its crest. This ring varies as to size ; it is larger in the male than the female, its average dimensions being from an inch, to an inch and a half in the longest direction, and about half an inch transversely. This opening is very interesting from the fact of its transmitting in the male the spermatic cord and cremaster muscle, and in the female the round ligament of the uterus, and particularly so to the surgeon, from being the seat of that form of hernia called oblique inguinal. Function. — Tlte external oblique assists in expiration by compressing the abdominal viscera, which press up the diaphragm, and thus diminish the thoracic cavity. It also aids in evacuating the foeces and urine, and brings the thorax and pelvis toward each other. Internal oblique — obliquus internus abdominis ascendens. (Fig. 167.) Dissection. — Kemove the external oblique by an MUSCLES OF THE ABDOMEN. 543 incision along the ribs, just below its origin; a second incis- ion is to be made from the anterior superior spinous pro- cess transversely through the aponeurotic tendon of the external oblique, to the linea alba, extending the incision along the crest of the ilium. The external ring and pillars will thus be left entire for subsequent examination. Dis- sect from behind forward and in the course of the fibres of the muscle. This muscle takes one of its names from the most of its muscular fibres pursuing an upward direction. It arises tendinous from the fascia lumborum, tendinous and fleshy from the whole of the crest of the ilium, and fleshy from the upper half of Poupart's ligament. The fibres of this muscle do not all ascend, those at the lower part pursue rather a transverse and downward direction. The fleshy portion is continued farther forward than the external oblique, and ends in a flat tendon, which at the outer edge of the rectus divides into two layers, one of which unites with the tendon of the external oblique to go in front of the rectus, the other joins the tendon of the transversalis and passes behind the rectus, thus forming a complete sheath for this muscle. About half way between the umbilicus and pubis, the whole of these tendons pass in front of the rectus, leaving this muscle to rest upon the peritoneum. The internal oblique is inserted tendinous into the ensiform cartilage, and the whole length of the linea alba, tendinous into the cartilages of the seventh and eighth ribs, and fleshy into the cartilages of the four inferior ribs, function. — The same as external oblique. Transversalis abdominis. — Dissection. — Remove the inter- nal oblique by incisions from the ribs above, and crest of the ilium and Poupart's ligament below. The dissection should begin near the crest of the ilium, as here will be seen an artery, the circumflexa ilii, and some cellular tissue, showing distinctly the line of separation between the two muscles. The fibres of this muscle run transversely. It arises tendinous from the fascia lumborum, from the inner margin of the whole crest of the ilium, fleshy anteriorly 544 MUSCLES OF THE ABDOMEN. and tendinous posteriorly, from the external half or third FIG. 169. j of Poupart's ligament, and ten- dinous and fleshy from the in- ner surfaces of the cartilages of the six or seven lower ribs. These fibres all end in a tendon, which near the linea semilunaris, unites with the posterior layer of the internal oblique, and is inserted into the ensiform car til- age, the whole length of the linea alba, the upper margin of the pubis, and the linea innominata- This tendon passes behind the rectus, except about midway be- tween the pubis and umbilicus, where the whole pass in front. The union of this tendon with that of the internal oblique at the crista of the pubis, receives the name of the conjoined tendon which forms the floor of the external ring. Function.— -To compress the viscera and aid in expiration. The rectus abdominis (Fig. 167) is exposed by a longitu- dinal incision through the tendons of the broad muscles, extending from the ensiform cartilage to the pubis, and turning these tendons over to the linea semilunaris, when both the recti muscles will be seen lying side by side, along the median line. They are long and straight, thicker be- low than above, and arise by a flat tendon from the supe- rior margin of the pubis between the symphysis and spine ; the fibres ascend and are inserted into the ensiform carti- lage, and cartilages of the fifth, sixth, and seventh ribs. The recti are about three inches in breadth, and present, FIG. 169 represents the Transversalis Muscle, a Latissimus dorsi. 6 Ser- ratus major anticus. c External oblique, d External intercostals. e Inter- nal intercostals. / Transversalis abdominis. g Fascia lumborum. h Sheath of the rectus, its posterior part, i Rectus abdominis cut off, and its sheath. j Rectus abdominis of right side, k Crural arch. I Gluteus maximus. FASCIA OF THE ABDOMEN. 545 three or four irregular transverse lines, which are tendin- ous intersections of these muscles, and called linece trans- verses Their situations correspond to the umbilicus, the ensiform cartilage, midway these two latter points, and sometimes helow the navel. These lines adhere strongly to the tendons, and linea alba in front, and are not often seen on the back of these muscles. Function. — To bring the chest and pelvis toward each other and compress the bowels. The pyramidalis , (Fig. 167,) situated at the lower part of the abdomen, is a short muscle and arises by a broad, fleshy, and tendinous base, from the superior border of the sym- physis, extending to the spine of the pubis, having the rec- tus behind, and the external oblique in front. Its fibres ascend in a tapering manner, and are inserted into the linea alba, halfway between the pubis and umbilicus. This mus- cle is placed- in a sheath between the tendons of the broad muscles, and is not unfrequently absent. Function. — To as- sist the rectus, and make tense the linea alba. The conjoint action of all these muscles is to lessen the cavity of the abdomen and compress the viscera, and, al- though they are voluntary muscles, and also aid in expi- ration, defecation, vomiting, and parturition, they do some- times act without the consciousness of the individual, and are referred to by Mr. Harrison as strong examples of the influence of the excito-motory nerves, in consequence of their sympathy with the lungs, larynx, stomach, bladder, and uterus, sympathies which cannot be traced to any direct nervous connection. Fasciae of the Anterior and Lateral Walls. — The fascia superficialis and the fascia transversalis. The superficial fascia is sub-cutaneous, and continuous with that covering the chest. It consists of condensed cel- lular structure, and is variable in consistency in different parts — being weak, and cellular in some, and aponeurotic in others. It is traced over the abdominal muscles below, to Poupart's ligament, to which it slightly adheres — and thence upon the thigh for a short distance — also upon the 35 546 FASCIA OF THE ABDOMEN. dorsum of the penis, forming a suspensory ligament. It gives covering to the spermatic cord, which descends into the scrotum, and is continuous with the fascia of the per- ineum. This fascia, called also Camper's fascia, is thin and weak above, and strong and dense below, where it envelops the glands and a quantity of adipose matter, and has hence received the additional name of adipo-gland- ular structure. About an inch below Poupart's ligament it becomes closely connected with the fascia lata, in conse- quence of which adhesion, femoral hernia is disposed to" take the upward direction. In some of the lower animals this fascia is well developed — presents a yellowish aspect, and is very strong and elastic, by which arrangement it is well adapted to protect and support the abdominal viscera. The fascia transversalis is situated beneath the trans- verse muscle, and rests upon the peritoneum. It is of va- rying strength and consistency at different points, being cellular in some, and decidedly aponeurotic in others. It is generally a thin tendinous membrane, distinctly fibrous and strong in each inguinal region, and closely adhering to the transverse muscle. It is attached to the inner mar- gin of Poupart's ligament its whole length, to the-crista of the pubes behind the common tendon of the internal oblique and transverse muscles, to the external margin of the rectus, thence lining the transverse muscle, and the whole of the abdomen as high as the thorax. The lower portion of this fascia is extremely interesting from its connection with inguinal hernia. As already stated, it is here very strong and aponeurotic, and closely attached to the whole of Poupart's ligament. Dissection, however, shows that it does not stop at this ligament, but that a portion can be traced beneath the crural arch, in front of the femoral vessels, called their anterior sheath; and backward, as continuous with the fascia iliaca, a strong membrane covering the iliacus and psoas muscles. Where these two fasciae meet and are united to Poupart's liga- ment, there is seen a white, dense line, extending, in some- FASCLE OP THE ABDOMEN. 54f what of a curve, from the femoral artery to the crest of the ilium, enclosing the internal FIG. 170. circumflex artery and veins. At this common point of union be- tween these three several struc- tures, protrusion of any of the viscera beneath the crural arch, from the femoral artery outward, is effectually guarded against both by the great strength of this union, and the firm support it gives to all the organs pressing upon this point. From an inch and a half to two inches from the spine of the pubis, and about a half or three- quarters of an inch above Poupart's ligament, there is an opening in this fascia, called the internal abdominal ring. It is found about midway between the symphysis of the pubis and spine of the ilium. Through this opening the spermatic cord, or round ligament, passes out of the abdomen. The opening is not distinct, as the cord, in passing through the fascia transversalis, pushes before it a reflection from this fascia, which, from its shape, is called the infwidibuliform, or fascia propria. From this internal ring or opening,, to the external ring in the tendon of the external oblique muscle, there is a canal called the oblique inguinal canal — a distance of about eighteen lines, along which the oblique inguinal hernia descends. This canal is bounded, in front, by the common integu- ments, superficial fascia, and tendon of the external ob- lique— behind, by the fascia transversalis, the conjoined tendons, and triangular ligament — below, by Poupart's FIG. 170 represents the Transversalis Fascia, and internal ring, a Internal oblique. 6 Part of transversalis. c Arched border of these two muscles form- ing the upper boundary of the inguinal canal, d Poupart's ligament, t Fascia transversalis. /Conjoined tendon of internal oblique and transversalis; letters « / form the posterior boundary of the canal, g Internal abdominal ring, k External ring, the dotted lines show the course of the cord. 548 BLOOD-VESSELS OF THE ABDOMEX. and Gimbernaut's ligaments — and above, by the fleshy mar- gin of the transverse muscle. BLOOD-VESSELS OF THE ANTERIOR AND LATERAL WALLS. The arteries are external and internal. The former arise from the femoral artery, ascend over Poupart's ligament, and consist of the ex- ternal or superficial circumflexa ilii, ex- ternal epigastric, and external pudic, pro- ceeding between the skin and superficial fascia, to be distrib- uted about the spinous process of the ilium, the umbilicus, and pu- bis. The internal or deep arteries have the same name, the prin- cipal of which are the circumflexa ilii proper, and internal epigastric, both of which come from the external iliac just as the latter is passing under Poupart's ligament. The latter ascends on the pubic side of the internal ring, between the fascia transversalis and peritoneum, to the rectus muscle, upon which it ramifies and ascends to anas- tomose with the internal mammary, which descends from FIG. 171 represents an internal view of the Anterior Abdominal Wall, with its Blood-vessels. 1 1 Linea alba. 2 2 Linea semilunaris. 3 3 Lineoe transversae. 4 Lower border of sheath of rectus. 5 6 Rectus abdominis. 7 Internal mammary artery. 8 Musculo-phrenic branch. 9 9 Diaphragm. 11 Section of the three abdominal muscles. 12 Section of external and inter- nal oblique. 13 External iliac artery. 14 Circumflexa ilii artery. 15 Ex- ternal iliac vein. 16 Crural ring. 17 Gimbernat's ligament. 19 20 Arch formed by the lower border of internal oblique, and transversalis muscle. 22 Conjoined tendon of internal oblique and transversalis. MUSCLES OP THE ABDOMEN. 549 the subclavian to supply the anterior abdominal walls. Each artery has one or two accompanying veins which open into the femoral, saphena, iliac, and subclavian veins- The nerves come principally from the lumbar plexus. The posterior walls of the abdomen include muscles, fas- cia, blood-vessels, nerves, and lumbar vertebrse. The muscles are quadratus lumborum, psoas magnus, psoas parvus, iliacus internus. The quadratus lumborum, situated between the last rib and the ilium, and composing a great part of the poste- rior abdominal wall, is FIG. 172. enclosed in a strong sheath, formed of the middle and anterior layers of the tendon of the transverse muscle. By removing the ante- rior layer of this sheath with the colon and kid- ney, the muscle is ex- posed. It presents an oblong form, and arises tendinous and fleshy from the posterior crest of the ilium and ilio lumbar ligament, and ascends to be inserted into the transverse pro- cesses of the last dorsal and four upper lumbar vertebrae by tendinous slips, and into the ver- tebral half of the last rib. Function. — To aid in expiration, by drawing down the last rib, and flexing the spine to one side. FIG. 172 represents Muscles of the posterior wall of Abdomen, a Quadratus lumborum. 6 Iliacus internus. c Psoas-magnus. d Psoas parvus. t Obtu- rator externus. 550 MUSCLES OF THE ABDOMEN-. The psoas magnus — t-oa, the loins, (Fig. 172,) is round, long, thick, fleshy above, and arises by two planes, the first fleshy from the sides of the bodies of the lumbar and last one or two dorsal vertebrae, the second from the trans- verse processes of all the lumbar vertebrae ; the two sets unite to form an oblong muscle, which descends along the lateral margin of the brim of the pelvis, beneath Poupart's ligament, and about its centre, and is inserted by a tendon common to it and the iliacus internus, into the trochanter minor, and fleshy for about an inch below into the linea aspera. A bursa is found between this tendon and the trochanter, and also between it and the pubis as it passes over. Function. — To flex the thigh on the pelvis, or the body on the thigh. It can also rotate the thigh outward. The psoas parvus (Fig. 1*72) has a short belly and along tendon. It arises fleshy from the sides of the bodies of the last dorsal and first lumbar vertebrae, and from the intervertebral ligament. Its tendon begins about the fourth lumbar vertebra, and passes down to be inserted into the linea innominata, and by a broad aponeurotic expansion into the fascia iliaca. This muscle is situated at the anterior and internal edge of the psoas magnus, and is often wanting. Function. — To flex the body or raise the pelvis, and draw up the sheath of the femoral vessels, which, it is thought, in sudden flexion will lessen the liability to injury of these vessels. The iliacus internus (Fig. 172) is situated on the outside of the psoas magnus, and fills up the venter of the ilium. It arises fleshy from the last lumbar vertebra by its transverse process, from the ilio-lumbar ligament, inner margin of the crista ilii, venter of the ilium, and intervening notch be- tween the two anterior spinous processes of the ilium — also from the capsule of the hip joint. It unites with the tendon of the psoas magnus, and is inserted along with it into the trochanter minor. A large bursa is found between this common tendon and the capsule of the hip joint, which occasionally communicates with the cavity of the joint. Function. — The same as the psoas magnus. FASCIA OF THE ABDOMEN. 551 FASCIA OF THE POSTERIOR WALL. Fascia iliaca. — This fascia, called also lumbo-iliac apon- eurosis, occupies the iliac region, and may be traced as a strong membrane covering the iliacus and psoas muscles, connected with Poupart's ligament from the anterior supe- rior process of the ilium as far as the external iliac artery, where it passes beneath this vessel upon the thigh, form- ing the posterior sheath of the femoral vessels, and being continuous with the pectineal portion of the fascia lata. Along Poupart's ligament it is also connected with, and continued into the fascia transversalis. The fascia iliaca can be followed below into the pelvic fascia ; above, after covering the psoas and iliacus muscles, as high as the diaphragm, it is connected to the ligamentum arcua- tum and sides of the lumbar vertebrse, where it forms a series of arches for the passage of the lumbar vessels and some of the nerves. This fascia has the double use of giving strength to the lower part of the abdomen by its firm union with Pou- part's ligament, and of furnishing a strong covering to the psoas and iliacus muscles. With the fascia transver- salis, it also forms a, sheath for the femoral vessels at the upper part of the thigh. At this point these two fascias are still further connected by two vertical partitions, one of which is between the femoral artery and vein, the other between the vein and the femoral or crural ring. Superior wall of the abdomen, (the diaphragm.) — Dissec- tion.— To expose this muscle, the abdominal viscera should be removed, and the loins raised by placing a billet of wood beneath the lumbar vertebra?. Then, dissecting off the peritoneum from the lower surface, the diaphragm will be seen as a movable curtain, dividing and separating the abdominal and thoracic cavities. This muscle is broad, and somewhat circular in its shape, consisting of a fleshy and tendinous portion, and presenting two surfaces — a superior arid inferior, or thoracic and abdominal, the upper surface being convex, the lower concave. The diaphragm 552 THE DIAPHRAGM. FIG. 173. is generally divided into two portions, called the greater and lesser diaphragm. The greater arises fleshy from the pos- terior part of the ensiform cartilage, from the inner sur- face of the cartilages of the seventh true, and all the false rihs, and for some extent fiom the osseous por- tion of the last two rihs. This origin, in- cluding almost a cir- cle, indigitates with the transversalis muscle. Between the ensiform cartilage and the ribs there is a triangular space containing cellular and fatty matter, and giving passage to the internal mammary vessels, in which there is occasionally found an opening through which some of the abdominal viscera pass into the chest, constituting hernia. From the circumference of this greater muscle of the diaphragm, the fibres radiate or con- verge to a central tendon called the cordiform tendon. This tendon, which has been compared to the heart of a playing card, is a tendiiious expansion of considerable extent, and of silvery whiteness, having its notch toward the spine and its apex to the sternum. All round its circumference the muscular portion of the diaphragm is attached to it. The lesser diaphragm consists of two crura, right and left, which are situated upon each side of the lumbar vertebrae. The FIG. 173 represents the Diaphragm or superior wall of the Abdomen. 1 2 3 Greater muscle of the diaphragm. 4 Space where hernia sometimes occurs. 5 Ligamentum arcuatum. 6 Origin of psoas-magnus. 7 Opening for lesser splanchnic nerve. 8 One of the crura of the diaphragm. 9 Fourth lumbar yertebra. 10 Another of the crura of the diaphragm. 11 Opening for the aorta. 12 Opening for the oesophagus. 13 Opening for the ascending cava* 14 Psoas magnus. 15 Quadratus lumborum. THE DIAPHRAGM. 553 right cms is the larger of the two and arises tendinous from the sides and anterior surface of the four upper lumbar ver- tebraB and their intervertebral ligaments; the left crus, being the smaller, comes from the two upper vertebra}. Both crura ascend and are connected upon the last dorsal vertebra by a tendinous cord, semilunar in shape, which arches over the aorta and thoracic duct. A little above this point the crura approach each other and decussate, and pass on to be in- serted into the notch and posterior margin of the central cordiform tendon. The greater and lesser muscles of the diaphragm have their attachments completed by the liga- mentum arcuatum, which extends from the transverse pro- cess of the first lumbar vertebra, and body of the second, to the twelfth rib. To the upper margin of this tendon the diaphragm is attached, and to its lower margin the psoas magnus muscle, and under it is placed the sympathetic nerve. The diaphragm contains three large openings ; one, for the aorta, thoracic duct, and great splanchnic nerves, is a long elliptical foramen, situated between and behind the crura, and in front of the bodies of the last dorsal and three upper lumbar vertebra?. The second opening is about three inches above and to the left of the aortic. Its form is that of a long oval, situated in the posterior part of the muscle, between the spine and notch of the tendon, the decussa- ting fasciculi forming its parietes and separating it from the aortic. The oesophagus and eighth pair of nerves pass through this foramen. The third opening is for the vena cava ascendens. It is a large foramen a little higher than the oesophageal, situated to the right and in the back part of the cordiform tendon. It is something of a quadrilateral figure, having its margins tendinous all round, with fasci- culi passing upon the vein above and below, and thus afford- ing an arrangement by which it is kept constantly open, and all interruption to the circulation prevented. The blood-vessels of the diaphragm are the phrenic, the first branches of the aorta after entering the abdomen, the internal mammary, intercostals, and branches from the re- nal and lumbar arteries. The veins open either into the ORGANS OF DIGESTION. cava or contiguous veins which pass into the same trunk. The nerves are numerous, supplying the diaphragm, and come from the phrenic, pneumogastric, spinal, and sym- pathetic. Function. — This muscle is an important agent in respira- tion. By its contraction its convex surface descends, and thus the diameters and cavity of the chest are enlarged and more air allowed to enter the lungs in respiration. By its contraction it also acts in concert with the abdominal mus- cles in vomiting, expelling the fasces, and in parturition. By its relaxation the diaphragm ascends into the cavity of the chest, diminishes this cavity and thus aids in expira- tion. The inferior wall will be examined in another place. SECTION II. ORGANS OF ABDOMINAL DIGESTION. These comprise, 1. The organ of cliymification, consist- ing of the stomach; 2. The organs of cliylification, com- posed of the small intestine and the large intestine, which however more properly belongs to the function oifcecation ; B. Assistant organs of digestion, composed of the liver, the pancreas, and the spleen. Before giving the description of the abdominal viscera separately, it is necessary first to premise a few general ob- servations upon the peritoneum, a membrane which is com- mon to each and the whole, and which forms the lining membrane of the abdominal walls. Peritoneum, (xtpitMtiv, to extend around.) — The perito- neum is a serous membrane, and the largest one in the body. Like all serous membranes, it is a shut sac. This is true of the male peritoneum, but in the female there is an opening at the extremities of the Fallopian tubes, which Mr. Harrison observes is more apparent than real, for he thinks it probable that these fimbrias are closed at all times except when in contact with or adhering to the ovaries. Thus, in ascites, the water is never found escaping by these openings, nor air, nor fluid, when injected in the dead PERITONEUM. 555 body; and if such be the facts, the female peritoneum can scarcely be said to form an exception to the general rule of all serous membrane, in FIG. 174. being a shut sac. Its structure is the same as all other serous membranes, being composed of an external layer of cellular tis- sue, and an internal one, which is pearly in appearance, smooth, semi-transparent, and by the mi- croscope is shown to consist of la- mina3 of flattened vesicles, with central nuclei. The external lay- er is connected with the sur- rounding structures, and con- ducts the nutrient vessels and „. nerves. The peritoneum has two great divisions, the one lining the abdominal walls and called its parietal; the second reflected over the viscera, and called its visceral portion. As FIG. 174 represents the Reflections of the Peritoneum. 1 Liver. 2 Stomach. 3 Small intestine. 4 Arch of the colon. 5 Duodenum. 6 Pancreas. 7 Rectum. 8 Uterus. 9 Vagina. 10 Bladder. 11 Peritoneum reflected from, diaphragm to Liver, and thence to the lesser curvature of the stomach, form- ing the anterior layer of the omentum minus, then 12 covers anterior face of stomach, and at 13 14 descends to form the omentum majus ; at 15 it is re- flected upward, forming at 16 the posterior layer of this latter omentum ; at 17 it surrounds the transverse colon, and extends back to the spine, forming at 18 the mesocolon ; it now goes in front of the duodenum 5, and descends to the small intestine 3, which it surrounds and furnishes the mesentery ; it next de- scends the posterior abdominal wall, covering the rectum 7, in front, the uter- us 8, bladder 10 ; and then ascends covering the anterior abdominal wall 20 and 21, to the diaphragm, place of beginning, at 22. If we start again from the diaphragm, we follow the peritoneum forming at 23, the posterior layer of lesser omentum, and at 24 the posterior layer of the stomach, and thence down- ward, forming, at 25 and 26, the posterior layer of the anterior fold of omentum majus, and then turns up at 27 to constitute the anterior layer of omentum, which goes to the anterior surface of the colon 4, and at 28 forms the anterior surface of the meso-colon, which is traced up to the pancreas 6, and on to the place of beginning. 556 PERITONEUM. this membrane is a shut sac, it is immaterial where we commence tracing it, as we must necessarily return to the place of beginning. If we start at the umbilicus, we fol- low it ascending upon the internal surface of the anterior abdominal walls, to the diaphragm, upon the lower surface of which it is reflected. From the diaphragm it passes on the left side upon the spleen, on the right to the liver, and in the centre upon the stomach. In this course from the um- bilicus there is also a distinct reflection to the convex surface of the liver, called the suspensory or falciform ligament, which receives the ligamentous remains of the umbilical vein. There are other reflections of this membrane upon the liver, which will be noticed in the separate description of this viscus. From the liver, after investing both surfaces, it is traced from the transverse fissure downward to the lesser curvature of the stomach. This reflection is called the lesser omentum, or gastro-liepatic omentum, and encloses the he- patic vessels ; at the lesser curvature of the stomach, the two laminse of this omentum separate, the one to pass in front of, and the other behind the stomach, to meet again along the greater curvature, thus completely investing this organ, ex- cept at the upper and lower curvatures, where this mem- brane separates and again unites. From the greater curv- ature of the stomach, the peritoneum descends to the lower part of the abdomen, and then turning upon itself, ascends to the arch of the colon, thus making this reflec- tion to consist, by its duplication, of four lamina?. It is called the omentum majus, or gastro-colic omentum. At the colon it again separates to enclose this intestine, and, upon the concave portion, unites to pass to the spine, forming another reflection, called the transverse mesocolon, which divides the abdominal cavity into two parts — supe- rior and inferior. From the spine the transverse mesocolon separates into an ascending and descending portion. The former is traced upward, over the lower part of the duode- num and the pancreas, to the posterior part of the right lobe of the liver, where it is continuous with the perito- neum of this organ, and the posterior layer of the lesser PERITONEUM. 557 omentum. The lower or descending layer passes over the small intestines, and round these and their vessels, to form a double lamina, which returns to the spine, forming a very broad and important reflection, termed the mesentery. The mesentery, besides blood-vessels, also encloses numerous lymphatic glands and absorbents. From the root of the mesentery we find its laminae stretching, upon either side, into the lumbar regions upon the right and left colon, con- stituting the right and left mesocolons, into the iliac regions, and thence into the pelvis, upon the rectum, forming the meso-rectum. From the rectum, of which it does not cover more than its upper two-thirds, it is reflected, in the male, upon the posterior and lower part of the bladder, forming two lateral folds, called the posterior ligaments of the blad- der, between which there is a depression or cul-de-sac. In the female this reflection passes first to the posterior and upper part of the vagina, then spreads over the uterus and to either side, forming the broad ligaments, which en- close the Fallopian tubes, ovaries, and round ligaments. From the front of the uterus the reflection proceeds to the bladder, and then ascends, as in the male, upon the sides and posterior surface of the bladder, to its fundus, whence it is traced upward, upon the posterior abdominal walls, to the umbilicus — the place where it was first opened. In this tracing of the peritoneum,, it is seen that it only gives a partial covering to many of the organs — as the duodenum, rectum, bladder, kidneys, &c. ; that all the vis- cera, even those having the most complete investment from it, are upon its external surface, and not within its cavity ; and that each organ gets its covering by simply pushing this membrane before it into the peritoneal sac. A famil- iar illustration is found in the double night-cap, showing how a shut sac may invest any thing, yet be on its out- side. The portion of the cap covering the head, resembles the peritoneum, covering the viscera, while the loose part of the cap, above the head, resembles the reflected portion of the peritoneum, upon the abdominal walls. About the neck of the gall-bladder, and at the base of 558 THE STOMACH. the lobulus Spigelii, is seen a large opening, called the fo- ramen of Winslow. It is by this foramen that the cavity of the omentum communicates with the cavity of the peri- toneum. If air he forced into this opening, it is found to pass behind the stomach, and fill the cavity of the omen- tum. Dr. Hodge, of Philadelphia, appears to be the first who has suspected the true use of this foramen, which is to introduce this lining lamina of the great omentum, so as to make it duplicate throughout. Function. — The peritoneum connects the several abdominal viscera, and retains them in their natural positions. It also conducts the various blood-vessels and nerves, and secretes a fluid by which its surfaces are lubricated, and friction diminished. THE STOMACH — (VENTRICTJLUS.) The stomach receives the masticated and insalivated food from the oesophagus. This organ presents the largest dilatation of the aliment- ary canal. It occupies the epigastric, left hypochondriac, and part of the right hypochondriac region, lying between the oesophagus on the left, and the duodenum on the right, with each of which it is inseparably connected. It has still further connections, by means of the peritoneum, to the diaphragm and liver above, through the reflection of the omentum minus ; below, to the arch of the colon, by the omentum majus ; on the left, with the spleen, by the omentum gastro-splenicum. Its shape is somewhat conoidal, with the base on the left side, whence it extends obliquely downward and forward, across the epigastric region, to terminate on the right side, near the gall-bladder, in the duodenum. It presents two surfaces, two curvatures, two orifices, and two extremities. The surfaces, are anterior and posterior. In the dis- tended state of the stomach, the anterior surface becomes superior, and looks towards the diaphragm, being in con- tact with the ribs and left lobe of the liver. The posterior surface presents towards the spine. The curvatures are su- perior and inferior, or lesser and greater. The lesser extends THE STOMACH. 559 FIG. 175. between the oesophagus and pylorus — presents upward and backward, and receives the omentum minus. The greater looks downward and forward, and has the omentum majus attached to it. Along these curvatures, the stomach is not covered by the perito- neum, and it is at these points that the separa- tion of the omentum occurs, and allow of that expansion of the stomach, in a state of distension, which it is believed to be their function to afford. A variety of opinions have been entertained in reference to the use of the omentum majus, into which we shall not stop to inquire, and will simply remark, in addition to what has been already said, un- der the head of perito- neum, that both its position and density vary very much. At one time it is found spread out as an apron, over the intestines, and at another, tucked up and hid by the stomach. At one time it is very thick, from being loaded with fat — while at another, it is entirely destitute of adipose matter, and extremely thin and transparent. FIG. 175 represents the Stomach and Intestinal Tube. 1 (Esophagus laid open. 2 Cardiac orifice of stomach. 3 Interior of stomach. 4 Duodenum commencing at the pyloric orifice of stomach. 5 Gallbladder. 6 6 6 Small intestine. 7 Coacum or beginning of large intestine. 8 Appendix vermifor- mis. 9 Right ascending colon. 10 Transverse colon. 11 Left descending colon. 12 Sigmoid flexure. 13 Rectum. 14 Anus. 560 THE STOMACH. The orifices of the stomach are the cardiac and pyloric. The cardiac is on the left side, and forms the termination of the oesophagus in the stomach. The pyloric is on the right side, and forms the entrance to the duodenum. It is lower than the cardiac, and is readily recognized by a cir- cular thickening of the parts. The extremities of the stomach are a greater ', which is in the left hypochondrium, and comprises what is termed the great cul-de-sac, which is situated to the left of the oeso- phagus, and in front of the spleen. The lesser is the pyloric extremity, which is to the right, much smaller than the left, of a cylindrical shape, and extends to the gall-bladder. The size of the stomach varies in different individuals, and in different conditions of fullness or emptiness. Its average capacity is estimated at about one quart. Structure. — The stomach consists of membranous tunics or coats, blood-ves- sels, and nerves. The proper coats are three, a serous, muscular, and mu- cous, to which is added the cellular, called the fibrous or nervous coat. The serous coat has been already described as be- ing a reflection of the peritoneum, coming from the omentum minus, and forming a complete investment of the stomach, except at its curvatures. The muscular coat presents three layers of fibres, which are usually pale, though variable as to color. The first FIG. 176 represents the Coats of the Stomach, a (Esophagus, b Cul-de- sac of stomach, or greater extremity, c Pyloric extremity, d Duodenum. e e Peritoneal coat turned back. / Longitudinal fibres of muscular coat, g Circular, h Oblique fibres, i Portion of muscular coat of duodenum. THE STOMACH. 561 layer is longitudinal; it is seen by raising the serous coat, Is external, and extends from the oesophagus, with the fibres of which it is continuous, and thence radiates to- wards the pylorus, being found, in greatest abundance, along the lesser curvature, though also seen upon the greater curvature and extremity. The second, or middle layer, is circular, commencing at the cardiac end, and increasing, in the strength and number of its fibres, as it proceeds to the pylorus. The fibres of the third or internal layer take u-e oblique course, are most distinct on the great extremity, and spread over the anterior and posterior surfaces of the stomach. The third or proper coat of the stomach, is the internal, •mucous, or villous. This is connected to the muscular by an intervening structure, termed nervous or fibrous, which consists of fibres closely united, dense and strong, and re- garded as the frame- F,G. 177. work of the mucous membrane, to which it gives support, and conducts its blood- vessels and nerves. The mucous mem- brane is a continua- tion of that lining the oesophagus, and, ac- cording to the obser- vations of Dr. Beaumont, is constantly covered with a vis- cid, transparent mucus. In its natural state it is of a light or pale pink color, varying, however, with the full- ness or emptiness of the stomach. It has a soft, velvet-like appearance, whence its name the villous coat. When deprived of its mucus, by washing, and examined with the microscope, in water, it presents a honeycomb FIG. 177 represents the Interior of the Stomach, a (Esophagus, b Cardiac orifice of the stomach, c Its cul-de-sac, d Greater curvature, e Where omentum majus is attached. / Muscular coat, g Cut edge of mucous coat. k Rugae of mucous coat, t Lesser curvature, j Where duodenum begins, k Pyloric orifice and valve. I Duodenum. 36 562 THE STOMACH. appearance, exhibiting numerous depressions, which are termed gastric pits, or favuli. These pits are surrounded by ridges, forming septa between them, which septa are Fio. ns. described as consisting of condensed cel- lular tissue, and containing mucous folli- cles, and many vessels. Each of these gastric pits is studded with foramina, four or five in number, which are re- garded as the orifices of the ducts, lead- ing from the glands, which furnish the gastric juice. These gastric glands consist of coecal pouches, or follicles, situated in the sub-mucous tissue; and of tubes, some of which are short and straight, others FIG. 179. longer and convoluted, all closely applied together, and terminating, by the above foramina, in the gastric pits. Mr. Beaumont observes that "when ali- ment or any irritant is applied to the surface, innumerable lucid points and fine nervous or vascular papillae can be seen, arising through the' mucous coat, from which distils a pure, limpid, colorless, slightly viscid fluid. This is invariably acid. The mucus of the stomach is less fluid, more viscid, semi-opaque, a little saltish, and has no acidity. The gastric fluid is never accumulated while fasting, and is seldom, if ever, discharged, except under the excitement of food, or some irri- tant. It is secreted only in proportion to the quantity of food supplied, provided there is not more of the latter than the sys- tem requires; and if an excess of food be taken, the residue either remains in the stomach, or passes into the bowels in FIG. 178 represents the Gastric Favuli on the inner coat of the stomach. *Fic 179 represents the Gastric Glands or Follicles, a Glands magnified three times, b Magnified twenty times. THE STOMACH. 565 a crude state." The free acid of this fluid is the hydro- chloric,* which, in combination with a peculiar animal matter, called pepsin, is believed to constitute the proper digestive principle. So potent is this principle represented, that the sixty-thousandth part, in acidulated water, im- parts to it digestive properties. The mucous coat also presents numerous rugge, folds or wrinkles, which are irregular in their course, size, and shape. The most prominent run in the long diameter of the stomach, and nearly parallel. They are most distinct about the pylorus. The texture of this coat is soft, easilj torn, and loose. It is covered by epithelium, which is more delicate, thinner, and softer, than that of the pharynx or O3sophagus with which it is continuous, and, unlike these, has the cylindrical instead of the laminated form. Where the stomach ends in the duodenum, the mucous coat forms a fold called the pyloric valve; around this valve the circular fibres of the muscular coat collect in the form of a bundle, and constitute a sphincter muscle, upon which depends all the efficacy of this valve in closing the open- ing from the stomach into the duodenum. About both ex- tremities of the stomach, the mucous -coat contains glands which resemble those of Brunner. They are thought to furnish mucus. Blood-vessels of the Stomach. — The arteries are the gastric or coronary, which comes from the cardiac axis, and runs along the upper curvature ; the right and left epiploic, and the vasa brevia, which come from- the hepatic and splenic arteries. The epiploic arteries run along the greater curv- ature, anastomosing and radiating in every direction, while the vasa brevia, which are five or six small branches from the splenic, pass to the left or greater end of the stomach. The corresponding veins enter into the vena portarum. The nerves are the pneumo-gastric, and the sympathetic. The former form a plexus around the cardiac orifice and ex- * Lehmann, Bernard, and Baneswil affirm that the free acid is lactic. Prout, Dunglison. Enderlin, Leibig, Bence Jones, and Graham, say that it is the. hydrochloric. 564 THE INTESTINES. pand upon the anterior and posterior surfaces. The^latter come from the solar plexus, and accompany the arteries- The lymphatics are numerous and traced to the glands along the curvatures. Function.— The stomach is the organ in which and by FlG- 18°- which is performed the first and most important step in di- gestion, the conver- sion of the food into a soft grayish homo- geneous, and slight- ly acid fluid called chyme ; this change is effected through the agency of the gastric fluid, which is brought into con- tact and thoroughly blended with every particle of aliment, by means of the motion communicated to both through the muscular apparatus of the stomach. THE INTESTINES, (Fig. 175.) The intestines comprise the whole of the alimentary canal, from the stomach to the anus. The length of this canal averages from thirty to thirty-five feet, though it measures more when separated from its connections and stretched out. Its size varies, and its shape is cylindrical. The intestines are divided into the small and large intestine. The small intestine is subdivided into the duodenum, the jejunum, and the ilium. The large intestine into the coecum, the colon, and the rectum. FIG. 180 represents the Arteries of the Stomach and its relation to the liver, pancreas, spleen, and duodenum. 1 Liver. 2 Stomach. 3 Duodenum. 4 Pancreas. 5 Spleen. 6 Cardiac artery. 7 Gastric artery. 8 Hepatic ar- tery. 9 Pyloric. 11 Right gastro epiploic. 17 Left gastro epiploic. 13 Cystic. 14 Splenic. 15 Pancreatic. 16 Vasa-brevia. 18 Superior mesen- teric artery. THE DUODENUM. 565 The small intestine reaches from the pylorus to the ilio-co3cal valve in the right iliac region. It is about an inch in diameter, is very much convoluted, and occupies principally the umhilical and hypogastric regions. The large intestine is much greater in size than the small, though only ahout one fifth of its length, and ex- tends from the right iliac region to the anus, occupying the most of the abdominal regions, and surrounding the small intestine like a ruffle. The whole of the intestinal canal has the same number of coats as the stomach ; serous, mus- cular, cellular and mucous. There are some differences, however, in this canal, which we shall briefly notice under its respective divisions. THE DUODENUM. The duodenum, so called from being twelve fingers' breadth in length, is the shortest portion of the small in- testine, though it has the greatest capacity. It is situated PIG> IQI in the right hypochondriac, right lumbar, and portion of the um- bilical regions. It takes a semi- circular course. Commencing at the pylorus, it ascends to the under surface of the liver, then makes a turn called its superior angle, and descends vertically in front of the right kidney as low as the third lumbar vertebra, where it makes a second turn, the inferior angle, then passes to the left side of the second lumbar vertebra, crossing the spine, and beneath the su- perior mesenteric artery, terminates in the jejunum. In consequence of its great dilatation, it has by some been regarded as a second stomach. The peritoneal coat of the duodenum furnishes a complete FIG. 181 represents the Interior of Duodenum and a portion of the Stomach. a a Pyloric end of stomach. 6 6 Folds and follicles of the mucous coat of the stomach, c Looks into the pylorus, d Thickness of pylorus, e e Rugae of mucous coat of duodenum. / Point of entrance of the ductus communis choledochus. 566 THE DUODENUM. covering only at the superior part, the inferior and trans- verse portions simply lying between the laminas of the mesocolon, without any proper serous investment. By this arrangement the superior portion of the duodenum only is movable, the rest being fixed. In the circuit it makes, it encloses the head of the pancreas, and at the posterior part of its second curve, the ductus communis choledochus, or the common biliary and pancreatic duct, is seen to enter. This duct sometimes enters as two separate tubes, and passes in either case very obliquely through the coats of the duodenum. The muscular coat has two sets of fibres ; the one longi- tudinal, thinly scattered and superficial, the second inter- nal, with its fibres arranged more closely together, so as to form a more perfect layer. They run circularly, though none surround the tube completely, forming only segments of circles. The muscular coat is rather pale and thin, though its color is deeper than that of any other portion of the small intestine. The mucous coat presents on its surface a series of folds or processes termed valvulce conniventes, which are perma- nent elevations of this membrane, and unlike the rugae of the stomach, which are only accidental, are not effaced by distension. At the lower part of the duodenum they are large and numerous, while they are few in number and small at the upper portion. They represent a succession of arches or duplications of the mucous coat, nearly parallel to each other, running round the tube in almost, though not entirely perfect circles, about three lines in breadth, though generally wider in the middle, and having their extremities frequently bifurcated. These valvulse greatly increase the extent of the absorbing surface of the chyle, and serve to retard the food in its downward passage, so that ample time shall be allowed for the extraction of all nutritious matter. On the mucous coat are also seen numerous little pro- cesses resembling the down upon the cuticle of an unripe peach, and hence called mill. They are described as being THE DUODENUM. 567 from one fourth to a line in length, and estimated by Meckel to be about four thousand to the square inch. These villi present, under the microscope, FIG. 182. a foliated or fungiform appearance, covered by epithelium, and containing a minute plexus of blood-vessels, and a lacteal tube, all united by cellular tissue. The lacteal forms the prominent part of | each villus. It commences, in the apex of the latter, by delicate branches, converging I to a single trunk, which proceeds to the base of the villus, and there unites with similar tubes from other villi. It is not yet fully settled whether the lacteals begin by open orifices, or by anastomosing loops. The latter opin- ion is most strongly urged, though observations are not wanting to prove the existence of both arrangements. Those who deny that there are any open mouths, explain the absorption of the chyle, on the principle of endosmosis. At the extremity of each villus, a mass of minute cells is described by Mr. Goodsir, as surrounding the loops of the lacteals. He regards them as true agents of absorption, first receiving the chyle, and, on becoming distended, transferring their contents, by solution or deliquescence, to the lacteals. It has been observed that, during digestion, these cells become erect and turgid with chyle, while in the interval they are found relaxed and empty, and pre- sent the appearance of a collection of granular germs. These cells are short-lived, being constantly destroyed, and as constantly renewed. Tbe mucous coat of the duodenum, besides the simple follicles of Lieberkuhn, scattered every where throughout the mucous tissue, contains also the glands of Brwiner, (Fig. 183.) These glands, situated in the sub-mucous tissue, sur- round this intestine in the form of a layer of white bodies of the size of hemp-seed, and of oval form. Each is said to contain several hundred follicles whose excretory ducts, FIG. 182 represents a Villus and the commencement of a Lacteal. 568 JEJUNUM AND ILIUM. like those of the sublingual gland, discharge separately FIG. 183. into the duodenum. The secretion of these glands is supposed to be like that of the pan- creas or salivary glands. The arteries of the duodenum come from the hepatic, splenic, and superior mesenteric. The veins go to the vena portae. The nerves come from the solar plexus. Function. — The duodenum completes the process of diges- tion, by changing the chyme, formed in the stomach, into chyle, and this by means of the bile and pancreatic juice poured into it from the liver and pancreas, through the common duct — the ductus communis choledoclius. The operation of the bile upon the chyme, is to separate it into three portions — one falls to the bottom, as a reddish brown sediment — another occupies the top, as a creamy pellicle, while the third remains in the centre, like fluid whey. The action of the pancreatic fluid, about which there has been nothing but conjecture, seems to be pretty fairly de- termined by the recent experiments of M. Bernard, which go to show that this fluid decomposes, and holds in solu- tion the fatty matters of the chyme, an effect, he asserts, which neither gastric juice, bile, saliva, nor any other agent can produce.* It is by the conjoint action of these two fluids upon the chyme, that another fluid, of the color and consistence of milk, is formed, called chyle, which is taken up by the lacteals of the villi, and introduced into the system. THE JEJUNUM AND ILIUM. The jejunum, (jejunus, empty,) so called from being found frequently empty; and the ilium, (from «x«v. to twist,) are situated in the umbilical, hypogastric, and iliac regions. The jejimum commences in the left lumbar, and the ilium Fie. 183 represents one of the Glands of Brunner. as seen at the commence- ment of the duodenum — magnified a hundred times. * See Ohio Medical and Surgical Journal, Vol. 1, No. 1, page 6J, 1848. JEJUNUM AND ILIUM. 569 FIG. 184. A B ends in the right iliac re- gion. There is no natural division showing where one of these intestines terminates, and the other hegins. The upper two- fifths, however, are gener- ally assigned to the jeju- num, and the lower three- fifths to the ilium. These intestines are very much coiled on each other, and are convex in front, and concave behind, where they are attached to the mesentery. The serous coat forms a complete covering to these intestines, except at the small trian- gular space where the hlood- vessels enter; consequent- ly there is free- dom of motion, though both are kept in their natu- ral places by their connection with the mesentery. FIG. 184, A represents a section of the lower portion of the Ilium, and com- mencement of the Colon, a a Ascending colon. 66 Ccecum, or caput coli. cc Lower portion of the ilium, d d Muscular coat, e e Cellular and mucous coats. // Folds of mucous coat at the beginning of the colon, gg Cellular coat prolonged into the folds, h h llio-colic valve, i i Where the coats of the ilium and colon unite. FIG. 184, B represents the Mesentery, a a Mesentery suspended. 6 6 b Small intestine, c Mesenteric glands. 5 TO JEJUNUM AND ILIUM. The mesentery (Fig. 184 B,) is a duplication of the perito- neum, having its root at the spine, about six inches in length, and extending obliquely from the second lumbar vertebra on the left, to the right iliac fossa. On the cir- cumference of this reflection are placed the intestines, while between its laminae are found the blood-vessels, nerves, lymphatic glands, and lacteals. The muscular coat is not so strong as in the duodenum, though it is thought the two sets of fibres are more dis- tinctly made out. They are pale and thin as in the duode- num. The longitudinal set shortens the tube, while the circular set constricts or lessens its diameter; the former pro- ducing the peristaltic, the latter the vermicular motion of the bowels. The conjoint action of the two carries on, step by step, the contents of this tube. The mucous coat presents thevalvulee conniventes through, the whole of the jejunum, more prominent than in the duo- denum. These valves decrease as they descend, till in the lower part of the ilium for about two or three feet they are entirely absent. The mucous follicles are abundant and exist every where, as in the duodenum and stomach, pre- senting the usual cribriform appearance. The glands of Peyer seem peculiar to the ilium, and are chiefly found at its lower part and opposite the mesentery. They are seen in clusters called glandulcc agminatce, (Fig. 25,) and present patches of small, white, circular raised spots, varying in size from a few lines to as many inches in length, and from eight to twelve lines in breadth. These clusters are mostly elliptical in their shape, and as many as thirty of them have been recognized in the ilium, coming nearer and nearer to each other as they ap- proach the termination of this intestine. The circular spots composing these clusters have few if any villi over their surface, but each one of them is observed to be surrounded by a circle of minute openings leading to the follicles of Lieberkuhn. There seems to be no connection between these follicles and the glands of Peyer, as the latter have no opening or excretory duct ; but on being ruptured are THE LARGE INTESTINE. 571 found to be cavities containing mucus and small cells in different stages of development. Blood-vessels of Jejunum and Ilium. — The arteries come from the superior mesenteric. The veins go to the vena portas. The nerves are from the solar plexus. Function.— The absorption of chyle by the lacteals, orig- inating in the various villi on the mucous surface of these intestines, seems to be their great duty. These villi becom- ing less and less numerous as we pass from the jejunum, the lacteals, and consequently the absorption of chyle, are found to diminish in like proportion. THE LARGE INTESTINE. The large intestine is from five to eight feet in length, and forms about one fifth of the intestinal canal. It is divided into the coecum, colon, Fie. 185. and rectum. It commences in the right iliac region where the ilium ends, and ascends through the right lumbar, to the right hypochondriac, then crosses the lower border of the epigastric and the upper edge of the umbilical to the left side, into the left hypo- chondriac region, whence it descends through the left lumbar and left iliac regions, ^o terminate in the rectum. This intestine is seen thus to traverse all the abdominal re- gions, and to form nearly a complete circuit enclosing the small intestine. It has the same number of coats as the small bowel. The peritoneum FIG. 185 represents the Large Intestine, a Termination of ilium. 6 Ap- pendix vermiformis. c Caput coli or ccecum. d Transverse colon, e De- scending colon. / Sigmoid flexure, g h Commencement and course of rectum. i Anus. 572 THE LARGE INTESTINE. gives only a partial covering, and is studded all along the large intestine with little reflections containing fat, called appendices epiploicce. In the ascending and descending colons, the peritoneal reflections are such as to receive the names of right and left mesocolon. The arch of the colon is almost entirely surrounded, has great facility of motion, and is kept in its place "by the reflection termed transverse mesocolon. This reflection goes back to the spine and divides the abdominal cavity into two parts, thus separating the stomach, liver, and spleen above, from the intestines below. The rectum is kept in position by the reflection termed meso-rectum. The muscular coat differs from that of the small intes- tine, in having its longitudinal fibres collected into three bands, which are equi-distant and about an inch in breadth; one of these bands is anterior, another internal, and the third external. These are white, strong, and elastic, and being shorter than the other coats, produce constrictions in its course, giving to this intestine a cellular , sacculated, or pouch-like appearance. These cells or pouches disappear when the bands are divided. These delay the too rapid passage of the faeces. The mucous coat differs from that of the small intestine in being almost if not entirely destitute both of villi and valvulae conniventes. The rugge that are seen on its sur- face do not belong to the mucous coat alone, but are formed by the other coats. Each of the different divisions of this intestine has peculiarities requiring separate notice. The coecum, (Fig. 1843 A) securely fastened in the right iliac fossa by the peritoneum, is from an inch to two inches in length, rounded below and convex externally. From its posterior inferior portion on the left side, it gives off a tortuous process, called appendix vermiformis, about the size of a goose quill, and varying in length from three to six inches. Its position also varies. It has a peritoneal covering which allows it to float loosely, and it is sometimes the cause of much mischief by surround- ing the ilium and producing strangulation. It is tubular. THE LARGE INTESTINE. 573 having a diameter of two or three lines, is composed of similar structures with the rest of the intestine, and com- municates with the coecum by a somewhat valvular ar- rangement. The use of this appendix is unknown. The coecum is joined on its left side, at an acute angle, by the ilium. The ilium seems to perforate the coecum, and at its point of entrance presents a transverse elliptical slit about an inch in length, (Fig. 184, A,) having access- ory fibres called retinacula, to strengthen its extremities. The sides of this slit constitute folds or valves ; the inferior or ilio-coecal, and the superior or ilio-colic valve. The for- mer prevents regurgitation from the coecum, and the latter from the colon into the ilium. This valve consists of two layers of mucous tissue investing cellular and muscular fibres, and is formed by the mucous coat and circular fibres of the ilium protruding through a separation in the circu- lar fibres of the ccecum. It looks downward. The colon (Fig. 185) is a continuation of the coecum up- ward, and is divided into the ascending, transverse, descend- ing, and sigmoid flexure. Its course and connections have already, to some extent, been given ; and it may be further added that the ascending colon passes in front of the right kidney, bordering the duodenum on the left, to the under surface of the liver, where, by its connection with the gall- bladder, it is frequently tinged with bile ; thence it makes its arch (transverse colon) across the abdomen, being bounded above by the stomach, and below by the small intestine. On the left it descends, being hid by the small intestine in front, and resting upon the kidney, it terminates in the left iliac region by a curve which goes first upward, then by one or more coils downward, to the sacro-iliac symphysis, where it ends in the rectum. This curve is called the sig- moid flexure. It is covered by a reflection of the peritoneum, allowing it frequently to be quite loose, and giving it con- siderable motion. The rectum, (Fig. 185,) so called from its straight course, is not so, strictly speaking, for commencing at the left ilio- sacral articulation, where the sigmoid flexure terminates, 5*74 THE LARGE INTESTINE. it proceeds obliquely downward, in the pelvis, to the mid- dle line of the sacrum, at the lower end of which, accord- ing to Mr. Harrison, it hends forward towards the peri- neum, then backward and downward, to end in the anus, about an inch or more from the coccyx. It presents, there- fore, a curvature both in the lateral and antero-posterior directions. The course of this intestine, however, varies, and, in the foetus, is almost invariably found straight, owing, doubtless, to the straight direction of the spine at that period. The size of the rectum varies ; small above, it expands below, just within the anus, into a wide pouch, which is not cylindrical, but flattened in front. In the male the rectum has the bladder, prostate gland, and vesicuhe sem- inales, on its anterior surface ; while, in the female, on the same surface, are the vagina and uterus. The peritoneum surrounds this intestine, only at its upper third, fixing it to the sacrum behind, by a reflection termed meso-rectum. In its middle there is only a partial covering in front and at the sides — while at its lower por- tion, or inferior third, it is entirely destitute of serous membrane, which is reflected from this point, upon the bladder in the male, and uterus in the female, forming, in each case, a pouch, or cul-de-sac, at the place of re- flection. The muscular coat of the rectum increases in thickness/ and exceeds greatly that of any other portion of the intes- tinal canal. The longitudinal layer, which exists as bands in the colon, spreads out and multiplies, and forms a complete tunic for the rectum ; and the circular layer also increases in strength and redness, in its descent, till, at the anus, its fibres become collected in a circular bundle, constituting the internal sphincter ani muscle. There are also some mus- cular fibres, surrounding the anus immediately beneath the integument, termed the external or cutaneous sphincter. Dr. Homer describes the longitudinal fibres, when they have reached the lower border of the internal sphincter, as turning under this border, between it and the external THE LARGE INTESTINE. sphincter, and then ascending for an inch or two, in con- nection with the mucous coat and its cellular structure, into which they are inserted. This arrangement explains the protrusion of the mucous coat in prolapsus ani. The mucous coat is thick and red, presenting at the upper portion of the rectum rather a smooth surface, while at the lower are seen longitudinal folds called columns, which allow of the distension of this intestine, and also some transverse folds which are not regular as to numher or FIG. 186. size. At the lower end of the columns, and between them, pouches are observed, (Fig. 186.) A radiated wrinkling is seen around the anus, which is formed by the contraction of the external sphincter. The margin of the anus is sup- plied with sebaceous follicles, and the whole mucous coat of the rectum abounds with mucous follicles. The arteries of the large intestine are branches of the superior and inferior mesenteric, and of the internal pudic arteries. Its veins enter into the vena porta?. The solar and hypogastric plexus of the sympathetic supply it with nerves. FIG. 186 represents a Section of the Anus and Rectum, showing the rectal pouches, a a Columns of the rectum, b b Rudiments of columns, c Inter- nal sphincter divided, d External spincter divided. t e Folds of skin on the Bates. / Pouches, g Brisiles in the pouches. 5*76 THE LIVER. Function. — To act as a reservoir for the ftecal matter, seems to be the principal use of the large intestine. But that it also possesses the power of absorption is proved by the fact of patients being sustained for weeks solely by in- jections of nutritious fluids into the rectum. ASSISTANT ORGANS OF DIGESTION, OR COLLATITIOUS VISCERA. The Liver, (hepar.) — The liver is justly regarded as one of the most important organs in the body, on account of FIG. 187. the very extensive influence it exerts, both in health and disease. It is situated, as already stated, in the right hypo- chondriac, extend- ing across the an- terior and upper portion of the epi- gastric, and occupying a portion also of the left hypochon- driac region. Thus placed, it is of course below the dia- phragm, to which it is attached by reflections of the peri- toneum, termed ligaments. These ligaments are five in number. The falciform or suspensory extends from the umbilicus, obliquely upward along the linea alba and the right side, to the diaphragm FIG. 187 represents the inferior surface of the Liver, a Right lobe. 6 Left lobe, c Anterior thin margin, d Posterior thick margin, e Right extremity. j Left extremity, g Notch on anterior margin, h Longitudinal or umbilical fissure, i Round ligament, j Portion of suspensory ligament, k Pons or bridge across umbilical fissure. I Posterior extremity of longitudinal fissure. m n Where ductus venosus joins the inferior vena cava. o Transverse fissure. p Section of hepatic duct, q Hepatic artery, r Branches of latter, s Vena portarum. t Division into right and left sinus vena portarum. u Remains of ductus venosus. v Gall-bladder, w Its neck, x Lobulus quartus. y Lobu- lus spigelii. z Lobulus caudatus. a a Inferior vena-cava. 6 6 Curve of liver. c c Depression for right kidney, d d Surface over renal capsule, e e Portion of liver uncovered by peritoneum. //Coronary ligament, gg Depression for the vertical column. THE LIVER. with which it is connected by its convex border, while its lower or concave edge is fixed to the upper surface of the liver. Along the inferior margin, and enclosed within its fold, is a cord, called the ligamentum teres'; this was formerly the umbilical vein of the foetus, now obliterated and converted into a closed ligamentous cord. It passes into the anterior notch of the liver. The third and fourth ligaments are the right and left lateral. The former is reflected from the pos- terior part of the diaphragm to the posterior margin of the right lobe. The left lateral comes from the same part of the diaphragm and goes to the posterior margin of the left lobe. The coronary ligament is described as extending from the suspensory towards the lateral ligaments, and as con- sisting simply of the lateral extension of the former. The liver lies in the concavity of the diaphragm, and is protected by the seven or eight inferior ribs. Below it is bounded by the stomach and duodenum, with which it is connected by the omentuin minus ; on the left is found the spleen, and behind are the ascending or inferior cava and vertebral column. The/orm of tlie liver has been compared to an ovoid cut in the direction of its long axis. Its average length is from ten to twelve inches, and its width from six to seven inches. The weight is from three to five pounds, though all these measurements are liable to great variation. Its color is usually a reddish brown, not unfrequently inter- spersed with dark patches, especially on the lower surface, which however are not morbid. The color of the liver, in- deed, varies as much as its weight and length. It is forihd red in the very young, and pale and yellow in the old. Its consistence is no less variable. It is generally firm, dense, and resisting, sometimes very hard and friable ; then again quite soft, so much so as to break readily under pressure of the fingers. This latter condition is often owing to a fatty degeneration. The surfaces of the liver are superior and inferior. The superior or upper surface is convex and smooth, fits in the concavity of the diaphragm, and is divided by the sus- 37 578 THE LIVER. pensory ligament, from front to back, into two unequal portions. The lower surface is very irregular, being marked by several eminences 'and depressions, or fissures. Eunning from the notch in the anterior edge of the liver backward, on a line corresponding with the direction of the suspensory ligament, is the umbilical or horizontal fissure, containing in its anterior portion the obliterated umbilical vein, and in its posterior the remains of the ductus venosus. This fissure divides the liver into its right and left lobes, and is sometimes converted at its anterior part into a complete tube, by a portion of the substance of the liver crossing it after the manner of a bridge and connecting its edges. The transverse fissure, situated near the centre of the lower surface, is quite broad, about two inches in length, and crosses the umbilical at right angles. It contains the hepatic artery and duct, the vena portarum, lymphatics and nerves, and cellular tissue which bind all these together. The right lobe is much the largest, and contains nearly the whole of the transverse fissure. Proceeding from it, behind the transverse fissure, and between it and the posterior part of the umbilical, is another lobe, called lobulus Spigelii or middle lobe. This lobe is somewhat pyramidal in its shape, and sends over the transverse fissure a projecting papilla, which is one of the porta or gateways of the liver. An elongation of the lobulus Spigelii, outward and forward along the right lobe and behind the transverse fissure, is called the lobulus caudatus. On the right lobe and in front of the transverse fissure, between the umbilical fissure and the gall bladder, is seen another elevation, not so distinct, called the lobulus quartus or anonymus. Its posterior ex- tremity is opposite the Spigelian, and constitutes the second port a of the liver.* * The author had an opportunity of witnessing a very curious transposition of parts on the inferior surface of a liver taken from a subject in the dissecting room of the Baltimore College of Dental Surgery. The following account was sent to the Medical Examiner, from which we quote : "I am sorry to say that I did not witness the removal of this liver, and did not see it in its natural situation, and cannot hence state, with positive certainty, which of the edges THE LIVER. 679 Structure or different elements of the Liver. — This organ consists of membranes, blood-vessels, hepatic ducts, lymph* atics, cellular tissue, nerves, and acini. The membranes are the serous, which has been noticed, and the fibrous. This latter consists of condensed cellular structure, which lies beneath the serous coat,, and forms the immediate covering to the whole surface of the liver, ad- hering to it, and sending innumerable processes every where into its substance, which both separate and surround the different granules or lobules, forming complete capsules for all the acini. This membrane also forms a sheath for all the vessels which enter or depart at the transverse fissure. This sheath follows and continues round the ramifications of these vessels throughout the liver, and takes the name of the capsule of Glisson. It is regarded in fact as the foundation structure of all the different elements composing this largest gland in the body. The blood-vessels of the liver are of three kinds, two of these pass in, the other comes out. The hepatic artery and vena portarum enter the liver, while the vena cava hepat- ico3 pass out. The hepatic artery is a branch of the coeliac axis, and as- of the liver presented front and towards the ribs— a fact of some interest, and in reference to which I have to regret my not being able to procure any infor- mation from those who removed it. " If where the umbilical vein or cord enters, be taken as the anterior edge of the liver, in accordance with the usual anatomical descriptions, then the state of things is as follows : " 1. The thickest edge, with its round and smooth surface, which is always described as posterior, is now found in front, while the anterior sharp edge is placed behind. 2. The right lobe is much the smallest, and about the size of what the left usually is, while the left was the usual size of the right. 3. The lobulus Spigelii is in front, instead of behind the transverse fissure, and on the left, instead of the right lobe. 4. The inferior vena cava was also in front of the liver, instead of its back part, and on the left instead of the right lobe. If, on the other hand, the thick and round edge of the liver, together with the usual situation of the lobulus Spigelii and ascending cava, be taken as the posterior edge, then the situation of the parts is as follows: 1. The gall bladder is on the posterior edge of the left lobe, instead of the anterior and inferior surface of the right. 2. The umbilical cord enters the centre of the posterior edge, instead of the fissure on the anterior edge. 3. The lobulus Spigelii passes over the transverse fissure to the left lobe." 580 THE LIVER. cends in the lesser omenturn to the transverse fissure of the liver, where it divides commonly into three branches, one of which passes to the right lobe, another to the left, and the third to the lohulus Spigelii. These branches follow the ramifications of the vena portarum, and biliary ducts, distributing upon each a complicated tissue of anastomosing vessels, ultimately breaking into a plexus for each of the acini. This artery is designed to nourish the liver. The vena port arum is very interesting from the curious fact of its having an origin as a vein, but a termination like an artery. It is very large, and is formed by a junction of the splenic and mesenteric veins, which receive the blood of the stomach, intestines, spleen, and pancreas, forming a tube from three to five inches in length, which is seen to commence be- hind the pancreas, in front of the aorta, and to ascend ob- liquely upward over the duode- num to the transverse fissure of the liver, where it divides into two branches, at right angles with the vein, called the sinus venaportarum. These branches are right and left. The right is the largest, but shortest, and radiates in minute branches to the right lobe, while the left after the same manner is distributed to the left lobe of the liver. This vein is accompanied by the hepatic artery. Both proceed from the centre to the circumference of the liver, and both are enclosed in canals termed portal canals, which are formed of the sheaths or processes from the capsule of Glisson. Injection shows that an anastomosis occurs FIG. 188 represents the Trunk of the Vena Porta with its roots and branches in the intestines and liver, a a Veins from the intestines. 6 Trunk of vena porta. c c Branches distributed in the liver. THE LIVER. 581 between the branches of the portal and those of the hepatic veins, as well as between both these and the artery. The capillary terminations of the vena portarum are distributed upon the acini, where they anastomose freely with each other and with the hepatic veins. This vein furnishes the blood for the secretion of the bile. The venae, cavce hepaticce, or the hepatic veins, commence in the acini, from the capillary terminations of the hepatic artery and vena portse, which successively converge into three large trunks, greatly exceeding, in size, the other vessels of the liver. Two of these come from the right lobe, the other from the left, and enter the superior cava, just as it is about passing through the diaphragm. Just below these are generally seen five or six, and sometimes more, hepatic veins, which return the blood from the lobulus Spigelii and other portions of the liver. In connection with these vessels, the umbilical vein should be mentioned. This vein is peculiar to the foetus, and car- ries the blood from the placenta of the mother, through the umbilical opening in the foetus, to the transverse fissure of the liver, where it divides — one branch being continuous with the vena portse, throughout the liver, the other pro- ceeding backward, in the posterior part of the umbilical fissure, to join the ascending cava. This is the ductus ve- nosus. After birth, both the umbilical vein and ductus venosus are obliterated and become ligamentous cords. , The hepatic ducts commence in the acini of the liver, by very fine branches termed port biliariij which, successively uniting, finally converge to the transverse fissure, by three or four trunks, which again unite into a single tube about an inch and a half long, called the hepatic duct. This unites, at an acute angle, with the cystic duct, forming, by their union, the ductus communis choledochus. This com- mon duct descends from the liver, behind the right extrem- ity of the pancreas, and in its substance, and then passes obliquely through the coats of the duodenum, to end by an orifice, marked by a papilla, on the mucous surface of this intestine, at the posterior part of its second curve. 582 THE LIVER. This duct is to the right of the artery, having the vena portaa behind and between the two. It has two coats — the internal is mucous, and the external fibrous. The use of the biliary ducts is to convey the bile, after its secretion in the liver, to either the duodenum or the gall bladder. The lymphatics are numerous and arranged into a super- ficial and deep set. The former are seen beneath the peri- toneum, in the form of a net-work. The latter pass out of the liver, at its transverse fissure, and go to the adjacent lymphatic glands, or enter the thoracic duct. The nerves come from the solar plexus, and accompany the blood-vessels into the liver. Some filaments are traced from the pneumogastric and phrenic. The Acini. — This element is best seen by tearing the liver, when it presents the form of granules, about the size of millet seed, which, from their resemblance to the seed of the grape, were called, by Malpighi, acini. Their shape is described as spheroidal, or polyhedral, and each one is con- sidered a perfect miniature of the entire gland, as each is composed of the capillary blood-vessels of the liver, with commencing radicles of the excretory ducts or pori biliarii. MICROSCOPIC ANATOMY OP THE LIVER. The observations of Mr. Kiernan are generally received as the most accurate, though their entire correctness has been called in question by some of the most respectable anatomists. According to this gentleman, the acini of Malpighi should be called lobules, as they contain still smaller granules, which he calls the proper acini, and which present two colors — a brown and a yellow, termed the cortical and medullary portions. This distinction, however, is now pretty generally aban- doned, the structures being regarded the same, and the difference in colors being considered as due to the higher vascularity of the brown, and the presence of bile in the origins of the pori biliarii of the yellow. The lobules present a rounded form with angular pro- jections. Each has a base which rests upon a hepatic vein, THE LIVER. 583 the sub-lobular, (Fig 189, B.) The base enters into the constitution of the walls of the sub-lobular vein, and the A FIG. 189. B remainder of the lobule has its sur- face covered with the cap- sule of Glis- son, in which the minute branches of the vena portae, hepatic vein, and hepatic duct ramify. The interior of the lobule has its centre (Fig. 189, A) occupied by a vein, called intra-lobular^ which connects it with the sub-lobular vein. The intervals, between the fis- sures of adjacent lobules, are called interlobular fissures ; and the spaces, formed by the apposition of several lobules, are called interlobular spaces. These spaces and fissures are, occupied by the delicate branches of the portal vein, hepatic artery and duct, termed each interlobular, and formed from the plexuses belonging to the sheaths, consti- tuting the portal canals, which are hence called vaginal plexuses. From the interlobular, branches of each set pro- ceed, and enter the lobules, forming plexuses in each, called lobular venous } and lobular biliary plexuses. The lobular plexus of the portal vein contains, in its meshes, the acini, or biliary plexus, and is traced into the intra-lobular vein, and thence to the sub-lobular, from which the hepatic veins are formed. It is not settled whether the terminations of the biliary ducts are coecal, or anastomosing arches. The lobules, thus constituted, are supposed to be nothing but a congeries of biliary ducts, surrounded by blood-ves- sels. More recent observations, with the microscope, make each acinus to consist of a collection of cells of various size FIG. 189, A represents the Lobules of Mr. Kiernan. a Intra-lobular vein. b Interlobular fissure, c Interlobular space. FIG. 189, B represents the Sub-lobular vein, a Lobule, b Intra-lobular rein, c Sub-lobular hepatic vein — a longitudinal section being made of it. 584 THE LIVER. and shape, containing bile with globules of fat; thus prov- ing, it is thought, that these cells are the real secreting agents of the bile, and that from these cells it is conveyed into the pori biliarii by a process not yet settled. The liver is developed by a protrusion from the intestinal canal. The gall-bladder (Fig. 187) is situ- ated in a depres- sion upon the an- terior part of the lower surface of the right lobe of the liver, and is a reser- voir for receiving the bile. Its form is conical; its larger portion, or fundus, projects somewhat 5 beyond the anterior edge of the liver, and looks to the right, downward and forward. Its narrow or constrict- ed portion, called the neck, is directed upward and baek- FIG. 190, A represents a horizontal section of three Lohules, displaying the two principal systems of Blood-vessels. Ill Interlobular veins in the spaces. 222 Interlobular veins in the fissures. 333 Lobular venous plexus. 444 Jntralobalar branches of hepatic veins. FIG. 190, B represents the Lobular Biliary Plexus. 1 Two lobules. 222 Interlobular ducts. 333 Interlobular cellular tissue. 4 4 Lobular biliary plexus injected. 5 5 Intra-lobular branches of hepatic vein. 6 6 Central por- tions of lobules uninjected. ff THE LIVER. 585 ward to the left, where it becomes somewhat convoluted, and ends in a tube, called the cystic duct, about an inch and a half long, which has already been described as join- ing the hepatic, to form the ductus communis choledochus , whose entrance into the duodenum has already been traced. The gall-bladder has three coats. The first, or perito- neal, is partial, covering only the anterior surface; the second consists of condensed cellular structure, and is called the fibrous ; while the third, which is internal, is the mu- cous coat. This coat presents wrinkles or folds which take a tortuous or spiral course, and have between them nu- merous cells, which give the surface of this coat a honey- comb appearance. This coat is always found colored, either yellow or green, from the bile. Blood-vessels. — The artery of the gall-bladder, the cystic, comes from the hepatic. Its vein goes to the vena portae. Its nerves come from the sympathetic. Its lymphatics are numerous, and unite with those of the liver. The gall- bladder is developed by an offset from the hepatic duct. function of the Liver. — The office of this viscus is clearly to secrete the bile, which secretion is found to occur in the lobules or acini, from the blood of the portal vein. The bile is a viscid fluid, of a yellow or greenish yellow color, and a very bitter taste. It is said to consist of chole- sterine, which is a white, fatty, crystallizable substance, re- sembling spermaceti; choleic acid, which is a peculiar animal substance combined with soda ; and coloring matter called biliverdin. The chemical analysis of Berzelius makes bile to consist of water, 80 parts ; bilin, a substance taking the resinous condition by the application of an acid, 8 parts ; mucus, 3 parts ; saline substances, of which soda is the prominent, 9 parts. The offices of the bile are, first, to act upon the chyme in the duodenum, in. its conversion into chyle; second, a por- tion of it unites with the residuum of the chyle, and is passed off by the bowels as excrement, thus ridding the blood of its superfluous hydro-carbon ; third, it excites the peri- staltic action of the muscular coat, and acts as a stimulus to 586 THE PANCREAS. increased secretion from the mucous follicles ; and fourth, the liver is regarded as the only organ for depurating the blood of its superfluous hydro-carbon, in the foetal state or before respiration is established.* , THE PANCREAS, (rtaj 2p£a$, all flesh.) This gland is next in importance to the liver, from the assistance it renders in completing the digestive process, the formation of the chyle. It is situated in the posterior epigastric region, behind the FIG. 191. stomach, and in front of the spine, the lesser mus- cle of the diaphragm, the „. aorta, ascending vena cava, and superior mes- enteric artery, and be- tween the two laminae of the mesocolon. Its direction is across the body, transversely from the spleen on the left, with which it is connected, to the curvature of the duode- FIG. 191 represents the Pancreas. 1 Head of the pancreas. 2 Neck. 3 Body. 4 Tail. 5 Pancreatic duct. * In addition to these functions, M. Bernard adds those of " sanguification and equilibrium." His recent experiments seem to show that the Liver forms sugar, fibrin, and fat ; that these three substances contribute to establish the equilibrium in the blood, and that no matter what the aliment is, the liver has the power to transform it into material fit for nutrition. Thus the composition of the blood is preserved in its proportionate number of regular, healthy ele- ments; for the sugar, fibrin, and fat, being thus furnished, restore to the blood again those substances which it is continually losing, and thus preserve the blood in a state of health. In a chemical point of view, the liver is considered an organ of sanguification. But the liver is also regarded as regulating the equilibrium of the circula- tion. Thus, in carniverous animals there is less fat secreted by this organ, because there is more taken, already formed, as aliment. In the herbiverous class, where there is much saccharine matter consumed, the liver forms less sugar ; and the less fibrin the stomach digests, the more it is found the liver contains. Consequently in man, whose diet is so variable, the blood will be furnished, by the liver, with that element in the largest proportion, which is found most deficient in his aliment, thus making this organ a balancing organ, or organ of equilibrium. From American Journal Medical Sciences, October, 1851. THE PANCREAS. 58*7 num on the right, (Fig. 180,) where it is closely attached, and from which it is often with difficulty separated. Its form is somewhat of a parallelogram, about seven inches in length, and two in breadth. Its color is of a light gray, or pink. Its structure resembles that of the salivary glands, so much so that it is called the abdominal salivary gland. It belongs to the conglomerate class of glands, and consists of lobules of various size, which are resolvable into still smaller bodies or granules, all of which are connected by cellular tis- sue, with their interstices occupied by blood-vessels. This gland has no proper peritoneal coat, nor investing tunic, unless the lamina of condensed cellular membrane which surrounds it, be considered as such. Its arteries come from the splenic, which courses the upper margin. Its veins enter the splenic, and thence the vena portas. Its nerves are from the solar plexus. Its excretory duct, called the ductus Wirsungii, is seen by scraping off some of the surface of the gland about its cen- tre, and is traced as a remarkably white and thin tube, extending from the left extremity or tail of the gland, to its right or head. Here it increases in size, and is some- times joined by a duct from the lesser pancreas, which is only an enlargement of the head. This duct, just before entering the duodenum, joins the ductus communis, though it is not unfrequently seen to enter separately. It arises by fine radicles from the granular masses, constituting the lobules, like the vesicular origins of the salivary glands. These unite to form the still larger tubes which proceed from the circumference to the centre, and discharge nearly at right angles into the common duct. Function. — To secrete the pancreatic fluid, which, as stated elsewhere, is conveyed into the duodenum ; with the bile, by their combined agency, it converts the chyme into chyle. But what part this fluid takes, or what is its special action in the process of chylification, all works on anatomy and physiology tell us is yet unknown. This uncertainty or obscurity as to the use of the pancreatic fluid, would seem to be entirely removed, and the question conclusively 588 THE PANCREAS. settled, by the recent experiments of M. Bernard.* The following is given by Prof. March as the substance of those experiments, at which he was present : " Pancreatic juice, when collected from a living animal (a dog for example) by means of a fistula artificially established, has clearly identically the same physical character as the saliva, being limpid, colorless, slightly ropy, and rather heavier than water. It is constantly alkaline, and is coagulable by heat and strong acids, owing to the presence of albumen. The saliva is slightly alkaline when collected pure, but never coagulable by heat or acids. When the pancreatic juice is put in contact with azotised aliments, as fibrin, albumen, and gelatine, there is no effect produced. Putrefaction oc- curs in time, but no digestion. When applied to farina- ceous substances, they are changed into sugar, which is ab- sorbable." Thus far, he states, is known. But it was not known before the discovery of M. Bernard, " that when this fluid, the pancreatic, is put in contact with fatty substances of every nature, as oils, animal fats, butter, &c., they are quickly digested or decomposed, and reduced to a state in which they may be absorbed into the circulation. This property is peculiar to the pancreatic juice, not being pos- sessed by the saliva, gastric juice, bile, serum, nor any other fluid of the animal economy. The first effect produced when you put the pancreatic fluid in contact with the oil, or any fatty substance, is to form an intimate emulsion, which will not separate on standing. If you agitate oil with saliva, gastric juice, serum or pure bile, or any other animal fluid, the mixture separates when in repose."f The great office of the pancreatic fluid then, in changing the chyme into chyle, seems to be to dissolve and hold in solution its fatty matters, that they may be capable of absorption. M. Bernard also states, as an established fact, *The facts stated above are taken from the first number, Vol. 1st, of the " Ohio Medical and Surgical Journal," for September, 1848. f Frerichs contradicts Bernard's statements on this point, but he has manifestly misunderstood them. The result of the experiments made by him, Bidder, Schmidt and Lenz, has been rather a modification than a refutation of his views. For a brief account of these results, see " Dental Chemistry," p. 144. THE SPLEEN. 589 " that the union of the bile and pancreatic fluid produces a new and distinct fluid, having, in addition to the peculiar properties of these two fluids, another superadded, that of digesting azotised substances, or, in other words, having the properties of the gastric juice." THE SPLEEN, (orttyv, lien.) The spleen (Fig. 180) is situated in the posterior part of the left hypochondriac region, having the diaphragm above, and the colon and kidney below, and the stomach and pan- creas upon its right. Its shape resembles an oval, cut in the long direction. Its color varies, though most generally it is a deep blue or purple. Its size also varies, being from four to five inches long, and from two to three inches wide. It is convex towards the ribs, and concave towards the stomach. In this concavity there is a depression called hilum lienis, in which the blood-vessels and nerves enter and pass out. Sometimes there are several spleens, in which case the superfluous ones are said to be not larger than nut- megs. Structure. — This organ (Fig. 192) has two coats, serous and. fibrous. The serous is a reflection from the peritoneum, FIG. 192. an(^ gives it a complete investment, except where the vessels enter. This coat attaches the spleen to several organs, as the stomach, colon, and diaphragm, by its reflections, called gastro-splenicj splenico-colic} and splenico-plire- nic ligaments. The fibrous or proper coat is closely con- nected with the serous, and is a thin, but compact, extensible, and elastic membrane, which not only surrounds this organ, but sends down into its substance innumerable fibres and lamellae, which traverse it in every direction, and divide it into partitions, making it cellular. This coat also forms sheaths for the blood- FIG. 192 represents the Spleen. Between 1 and 2, hilus or fissure of the spleen, where the blood-vessels enter and pass out. 4 One of the larger branches of the splenic artery. 5 Splenic vein. 590 ABSORBENTS OF THE TRUNK. vessels in their distribution through this organ. The cells are filled with a bloody pulp, of a grumous character, in which the microscope detects a number of small oval corpus- cles, of a reddish color, and about the size of the red globules of blood. The spleen contains also some small bodies, called after Malpighi, which are described as being about the third of a line in diameter, and consisting of con- voluted blood-vessels and lymphatics, connected by elastic tissue, and resembling minute lymphatic glands. They are said to contain lymph of the color of milk. Blood-vessels. — The splenic artery, the largest branch of the cceliac, takes a tortuous course along the superior mar- gin of the pancreas, and enters the hilum of the spleen by five or six branches, which ramify minutely throughout its substance. Injections have shown that the different branches do not anastomose,, hence each branch is regarded as having an independent function, and the spleen as con- sisting really of several organs like the conglomerate glands. The veins are numerous, having thin coats, and presenting enlargements, which are compared to the corpus cavernosum penis. These differ from the arteries by anastomosing freely with each other, and unite to form the splenic vein, a very large trunk, which is one of the principal roots of the vena porta3. This vein, like the rest of the portal veins, is without valves. The nerves come from the solar plexus and accompany the artery. The lymphatics are superficial and deep, and go to glands at the hilum. Function. — The use of this organ is unknown, but, not- withstanding this, there is no scarcity of speculations about the matter. The most generally received theory is, that it serves as a reservoir or diverticulum, when the abdominal organs are threatened by undue congestion of the portal system. SECTION III. ORGANS OF ABSORPTION OF THE TRUNK. The organs of absorption naturally follow, in the physi- ological arrangement, those of digestion; for while it is ABSORBENTS OF THE TRUNK. 591 the office of the latter to convert the crude aliment into chyme and chyle, it is the business of a portion of the for- mer to take up this chyle, thus prepared for the nutrition of the body, and introduce it into the circulation, whence it is conducted, along with the blood, to the lungs, where it receives its final and finishing stroke as blood, to be now taken up, by the organs of circulation, and distributed throughout the system for the support of every part. The organs of absorption comprise three sets of struc- tures— the lactealSj lymphatics, and lymphatic or absorbent glands. Under the head of glandular tissue, some general re- marks are made upon the absorbent system. The lacteals (Fig. 182) and lymphatics are regarded as parts essentially of the same system of vessels, though having different names. The structure of both is the same, consisting each of two coats — an external, which is regarded as fibrous by some, and muscular by others ; and an internal, which is very delicate and transparent, resembling that of the veins. A middle coat is also spoken of, which is thin, as in the veins, but destitute of the elastic lamina. Like the veins, the internal coat of the absorbents presents numerous folds constituting valves. These valves are of semilunar shape, and arranged in pairs, giving the vessels containing them a braided or knotted appearance, (Fig. 18.) These valves prevent the retrograding of the chyle and lymph. The absorbents, like the veins, are divided into the superficial and deep, and have their fluids running the same direction. The trunks of the absorbents terminate in the venous system; hence these two are only regarded by some as continuations of one and the same system. This difference however is observed, that all the absorbents, whether superficial or deep, converge and pass through a set of bodies called lymphatic or absorbent glands, while veins do not. The absorbents, on entering these glands, are termed vasa inferentia, and on passing out vasa efferentia. These glands, as elsewhere stated, are very numerous, pre- senting a reddish, or gray color, varying in size from a cur- 592 LYMPHATICS OF THE STOMACH. rant to an almond, and mostly of an oval or round form. Their consistence is firm, each being surrounded with a fibrous capsule. They generally run in chains or clusters. The division of the absorbents into lacteals and lymphat- ics, is founded on the color of the respective fluids ; the chyle of the lacteals resembling milk, while the lymph of the ab- sorbents looks like serum or water. The lacteals are limited to the abdomen, and have their origin in the numerous villi of the small intestine, espe- cially its upper portion,- which converge to the mesenteric glands, through which they pass, and thence proceed, after being reduced to one or more trunks, along the superior mesenteric artery to its root, where they enter the thoracic duct. The mesenteric glands are situated between the lam- inse of the mesentery, and are estimated at about one or two hundred in number. The lymphatics are found in every part of the body, ex- cept the interior of the brain, spinal cord, cartilages, ten- dons, and ligaments, and though they are not as yet demonstrable in these parts, there is, nevertheless, the strongest reason, from analogy, for believing that they exist there. Their function is to absorb from every tissue all the particles of matter that have become effete,, useless, and as it were, worn out, and. to conduct these into the thoracic duct, there to mingle with the chyle from the lac- teals, and thence into the circulation, or as in the right head and neck, and right upper extremity, to go more di- rectly into the venous system. The lymph then, like the chyle, is carried into the venous circulation, is mingled with the venous blood, and conducted to the lungs, where the purification and conversion into arterial blood occurs, so that it is fitted to enter the system, and perform the same office of nutrition as before. THE LYMPHATICS AND GLANDS OF THE STOMACH. The lymphatics of the stomach are superficial and deep . The former present a plexiform arrangement beneath the peritoneum ; the latter, a similar appearance in the mucous LYMPHATICS OF THE INTESTINES. 593 coat, converging from different directions, thus accompany the epiploic and coronary vessels to the glands, along the greater and lesser curvature of the stomach, amounting to eight or ten in number, through which they pass, and thence proceed to the thoracic duct. Some are seen going to the glands of the spleen, and others to those about the pylorus. LYMPHATICS AND GLANDS OF THE INTESTINES. The lymphatics of the small intestine, like those of the stomach, are superficial and deep, the former being situated beneath the peritoneum, the deep in the mucous coat, or between the latter and the muscular. Both sets enter the mesenteric glands, and go, as stated, to the thoracic duct. The lymphatics of the large intestine are not so numerous as those of the small. They have a like division into super- ficial and deep, and also follow the course of the blood-ves- sels. Those of the ascending and transverse colon unite with the lymphatics of the mesentery; while those of the descending colon and sigmoid flexure enter the lumbar glands. The lymphatics of the rectum do not all go to the lumbar glands — part of them enter the hypogastric. The lumbar glands are very numerous, and found along the course of the common iliac arteries, continuous with the pelvic chain, also around the aorta, ascending cava, on each side of the bodies of the lumbar vertebrae, and, in fact, scattered in every direction from the base of the sacrum to the diaphragm. These glands not only give passage to the lymphatics of the left portion of the large intestine, but they also' receive all those of the pelvis, corresponding to its several viscera, which, after passing through the iliac, sacral, and lumbar glands, finally enter the receptaculum chyli, by several large trunks which form the commence- ment of the thoracic duct. LYMPHATICS AND GLANDS OF THE LIVER. The lymphatic vessels of the liver are superficial and deep, and exceedingly numerous. They are readily in- 38 594 LYMPHATICS OF THE CHEST. jected from any of the large trunks, by the yielding of the valves. The superficial set are found all over the convex and concave surfaces of the liver, pursuing dif- ferent directions. On the convex surface some are seen to enter' the suspensory ligament and pass through the diaphragm to the glands in the anterior mediastinum; others go to the horizontal, thence to the transverse fissure, and on to the glands of the omentum minus and pylorus ; while others are seen to accompany the vena cava into the chest, and enter the thoracic duct. On the concave surface of the liver they are equally numerous, some passing to the lesser omentum, and others to the superior lumbar and inferior intercostal glands. A distinct plexus is seen around the gall-bladder. The deep lymphatics of the liver take the course of the portal vessels and biliary ducts, and pass to the glands of the lesser omentum, and thence back to the spine to enter the thoracic duct. The lymphatic glands of the liver are found along the hepatic vessels, and continuous with those on the coeliac artery. The Lymphatics of the Pancreas and Spleen pass to the glands along the splenic artery, and finally terminate in the thoracic duct. The lymphatics of the abdominal parietes follow the course of the epigastric, ilio-lumbar, circumflexa ilii, and lumbar arteries, and go to the iliac and lumbar glands. Those of the diaphragm join the intercostal and internal mammary, THE LYMPHATICS AND GLANDS OF THE CHEST. The lymphatics of the chest are divided into the parietal and visceral. The former pursue the course of the thoracic, internal mammary, and intercostal vessels, and go to the axillary, inferior cervical, and intercostal glands. The visceral lymphatics belong to the lungs, the heart, and thymus gland. Those of the lungs are superficial and deep. The former are spread as a net-work over the pulmonary surface be- neath the pleura, and proceed to the root of the lungs to LYMPHATICS OF THE CHEST. 595 enter the bronchial glands. The deep-seated take the course of the bronchial vessels and tubes, and also go to the bronchial glands, and the thoracic duct, and some to the right lymphatic duct at the base of the neck. The lymphatics of the heart accompany the coronary ves- sels and proceed to the bronchial glands, and thence to the left thoracic duct. The lymphatics of the thymus gland, go to the bronchial glands ; and those of the oesophagus, which are found to be very numerous, so much so as to form a continued plexus around its whole extent, also enter the bronchial glands. The lymphatic glands of the chest are also parietal and visceral. The former are found near the heads of the ribs, between the intercostal spaces, posterior to the sternum, along the internal mammary vessels, a few in the anterior mediastinum reaching from the diaphragm to the neck, and a chain of them along the oesophagus and aorta in the posterior mediastinum. The visceral glands are the bronchial or pulmonary, which are situated about the root of the trachea at its di- vision, and pursue the course of the bronchia for some dis- tance into the structure of the lungs. They are numerous and large, and are estimated at from ten to twenty in number. Their most striking peculiarity is their color, which is black, and is stated to depend upon a deposition of carbon from the bronchial lymphatic vessels. In early life these glands are of a reddish color, then gray, and finally black. The left or great thoracic duct, which is the common tube for the lymphatics of all the viscera and structures below the diaphragm, as well as those of the left side of the chest, left neck, head, and left upper extremity, commences below the diaphragm in the receptaculum chyli, passes up the chest between the aorta and vena azygos, and finally terminates at the junction of the left subclavian and inter- nal jugular veins. Its course is more fully described under the head of glandular tissue. ORGANS OF THE CHEST. The right lymphatic duct receives the lymphatics of the right side of the chest, right lung, right diaphragm, right upper extremity, right neck, and head, is about an inch in length, and enters the angle formed by the junction of the right subclavian and internal jugular veins. This is the most common disposition of the two thoracic ducts, but there occasionally occur varieties in their origin, course, and termination. CHAPTER IV. THE ^ORGANS OF THE TRUNK. THIRD DIVISION. ORGANS OF THE CHEST. IN the physiological order these organs are divided into the organs of respiration, and the organs of circulation. GENERAL OBSERVATIONS ON THE CHEST. The cavity of the chest or thorax occupies an inter- mediate situation and size, in comparison with the other two great cavities of the trunk, the cranial and abdom- inal, and intermediate also in relation to the structure of its walls; for while those of the abdomen consist in great measure of soft parts, and those of the head of a hard and complete bony case, the walls of the thorax, on the other hand, combine the properties of both, in consisting of hard and soft parts in nearly equal proportions, and thus har- moniously blending the fixed and dilatable conditions of each. Some general remarks have already been made under the head of passive organs of the trunk, where it was stated that the thoracic cavity presented the form of a truncated cone, with the apex above and base below, flattened before and behind, and convex at the sides; that its form and diameters are liable to variation both from disease and MUSCLES OF THE CHEST. 597 mechanical appliances, and that its appearance is very different when viewed after having the upper extremities detached. In this condition, with the arms removed, the chest looks larger, as it really is, below than above, while in the living state, or with the bony shoulder and arms ap- pended to the skeleton, this cavity looks larger above than below, which it is not. The chest is bounded, as stated, by the sternum and costal cartilages in front, by the dorsal vertebrae behind, the diaphragm below, the ribs and the in- tercostal muscles laterally, and the superior opening of this cavity, which is occupied by the passage through it of the trachea, oesophagus, muscles, vessels, nerves, and cellular tissue, above. It is also lined by a serous membrane, which is reflected from its interior walls over the lungs and peri- cardium, called the pleura. All these parts have been de- scribed elsewhere, except the muscles on the anterior walls of the chest and pleura, which we shall now proceed to notice. SECTION I. MUSCLES OF THE CHEST. Dissection. — Make an incision through the integuments from the upper edge of the sternum along the median line to the xiphoid cartilage. From the upper end of this incision carry a second along the clavicle to the acromion process, and from its lower end a third along the lower margin of the great pectoral muscle, which is readily seen, to the humerus. Kaise the integuments by commencing the dis- section along and in the direction of the third incision for the right side, and from the second incision for the left side. This will be exposing the great pectoral muscle in the direction of its fibres. A superficial fascia will be raised at the same time with the integuments, which is both delicate and cellular, and continuous above with the superficial fascia upon the neck, and below with the same upon the abdomen. The Pectoralis Major (Fig. 167) arises fleshy from th anterior two-thirds of the clavicle, tendinous from the an- 598 MUSCLES OF THE CHEST. terior surface of the sternum, the whole length of its two upper bones, meeting its fellow tendon of the opposite side along the median line, where they decussate, and thus cover the sternum with a kind of aponeurosis. We have, however, several times seen the sternal origin of this muscle entirely fleshy, and meeting its fellow in the same way along the median line. It also has a fleshy origin from the fifth and sixth ribs, sometimes also from the third and fourth, and a slip, sometimes fleshy and sometimes aponeurotic, is seen to connect the lower portion of the costal portion with the upper tendon of the external oblique or rectus muscle. From these several origins the fibres pursue different directions, the clavicular descend, the sternal run horizontally, and the costal ascend — the whole uniting into one broad, thin tendon, which is inserted into the anterior edge of the bicipital groove. At the axilla the muscle is folded inward, presenting a thick, rounded margin, and at its insertion the clavicular portion is seen to descend lower than the sternal, thus producing a decus- sation of its tendinous fibres. Function. — To draw the arm inward and forward upon the chest. If the arms be fixed, this muscle can elevate the ribs, and thus aid in inspiration. If the arm be raised, the costal portion can draw it down ; and by the action of both muscles the arms are folded upon the chest. The Pectoralis Minor (Fig. 167) is triangular in shape, and seen by raising the last from its origin, and turning it over towards the humerus. It arises by thin tendin- ous digitations from the third, fourth, and fifth ribs at their superior margins, proceeds obliquely upward and outward, and is inserted by a short, flat tendon into the inner face of the coracoid process of the scapula. Function. — To draw the shoulder inward, downward, t'nd forward, and to assist the great pectoral in inspiration, by raising the ribs, when the scapula and arm are fixed. Serratus Major Anticus, called also Serratus Magnus, (Fig- 193.) — This muscle is distinctly brought to view by raising both pectoral muscles, detaching the clavicle from thester- MUSCLES OF THE CHEST. 599 FIG. 193. num, and throwing the whole back towards the spine. It will then be seen as a thin, broad muscle, covering the sides of the chest, and situated between the ribs and the scapula. It arises from the eight or nine upper ribs, by as many fleshy digitations. The five lower interlock with the ex- ternal oblique muscle, the upper one is short, thick, some- what square, and is thought to resemble a distinct mus- cle. Its fibres converge and are inserted into th whole base of the scap- ula. Function. — To draw the shoulder forward, and when the scapula is fixed it can draw the ribs outward, and aid in inspiration. The intercostales (Fig. 193) occupy the spaces between the ribs, are twenty-two in number, and divided into an ex- ternal and internal set. The external arise from the transverse processes of the dorsal vertebras, and from the inferior acute edge of each rib, and then proceeding downward and for- ward in fasciculi, are inserted into the superior smooth border of the rib below to within a short distance of the costal cartilage, the intervening space to the sternum FIG. 193 represents the Serratus Major Anticus Muscle. 1 Anterior portion of cervical vertebrae. 2 Transverse process of the second cervical vertebra. 3 6 Scalenus anticus. 4 Levator anguli scapulae. 5 Lower edge of serratus magnus. 7 Scalenus medius. 8 First rib. 9 Coraco-clavicular ligaments. 11 Clavicle. 12 Base of scapula, where the subscapularis is attached. 13 Upper portion of serratus magnus. 14 Lower portion of subscapularis. 15 15 Origin of serratus major anticus. 16 Internal intercostal muscles. 17 Ex- ternal intercostals. 600 MUSCLES OP THE CHEST. being filled by aponeurosis. The internal arise from the sternum and inferior margin of each cartilage and rib, descend backward, decussating the external, and are in- serted into the superior margin of the cartilage and rib below, as far back as the angles of the ribs. These two sets are separated by the intercostal vessels and nerves. Function. — To raise the ribs, and enlarge the chest in inspiration, the first rib being first fixed by the scaleni. The subclavius arises tendinous from the cartilage of the first rib, forms a small round muscle, situated immediately beneath the clavicle, and is inserted into the exterior half of this bone, as far back as the ligament connecting the coracoid process and clavicle. Function. — To draw the clavicle and shoulder down- ward. The triangularis sterni arises from the posterior surface and edge of the ensiform cartilage and lower part of the sternum. Its fibres run obliquely outward and upward, to be inserted by fleshy and tendinous digitations into the cartilages of the third, fourth, fifth, and sixth, and some- times as high as the second rib. Function. — To draw the ribs down and aid in expiration. Situated upon the anterior lateral regions of the chest are the two mammce or breasts. These are glandular or- gans, and belong to the conglomerate order. They rest upon the great pectoral muscles, and between the third and seventh ribs. The skin over the breast is thin, smooth, and soft, and in the virgin, of a rather pale, inclined to a bluish tint. In those who have borne children, and are ad- vanced in life, the skin loses its smoothness and becomes wrinkled, more uneven, and of a darker color. About the centre of the gland the nipple is seen, which may be either long or short, sometimes so short that with difficulty the child takes hold of it. It consists of the lactiferous or milk ducts connected by cellular tissue. It presents the form of a cone in the virgin, while it has a flattened, cribriform appearance in one giving suck. It is capable of erection, and is thought by some to have the erectile tissue, while MAMMARY GLAND. 601 others think it does not possess that spongy, cavernous character of the true erectile, but resembles more the dartoid structure. It is surrounded by an areola, which is of a rose color in the virgin, and in the pregnant or lactat- ing female becomes of a dark brown. Both the nipple and areola present over their surface numerous small tubercles, sebaceous follicles, and nervous papillae. Each tubercle presents near its apex three or more foramina, which are the openings of the excretory ducts from the gland com- posing the tubercle, and whose secretion, it is believed, is designed to protect the nipple from excoriation, while there are some who regard these tubercles as lactescent. Be- neath the skin and front surface of the mamma an abund- ance of cellular tissue intermixed with globules of fat is seen, which makes the volume of the gland appear much larger than it really is. Structure. — The mammary gland is surrounded by a cap- sule of cellular membrane, which sends down processes into its substance, separating and connecting its different parts. It consists of lobes which are divided into lobules, and these again into granules, about the size of millet seed, which, under the microscope, are found to contain vesicles. (Fig. I1?.) The lobules give the exterior surface of the gland a very uneven appearance, from being separated at different depths, by irregular fossae which are filled with adipose and cellular tissue. From the vesicles of the sev- eral granules, the excretory or lactiferous ducts have their origin. The ducts as well as the granules are known by their white color. They converge from all parts of the gland to the base of the nipple ; in their course, dimin- ishing in number, but increasing in size. The termination of these ducts, at the base of the nipple, is in sinuses, res- ervoirs, or ampullae. As many as fifteen of these sinuses are enumerated, having different diameters. From these about twelve or twenty ducts pass through the nipple to its extremity, and there open by as many orifices. These ducts (Fig. 194) are lined by mucous membrane, and when in a state of erection are doubled or folded upon them- 602 THE PLEUEA. selves, thus forming valves to prevent the escape of the milk when not needed. These ducts, however, have no true valves, and injection shows them to have no communication with each other. The interior of the mammary gland, when a section is made, presents a white, fibrous appearance, in which the granular arrangement is not so distinct, unless the ex- amination, it is remarked, be made during lactation. The arteries supplying this gland come from the thora- FIG. 194. cic, the intercostals, and inter- nal mammary. The veins are superficial and deep — the lat- ter accompanying the arteries. The nerves are derived from the brachial plexus and inter- costals. The lymphatics of the mammae are numerous, some of which are traced to the glands of the ax- illa, others pass through the intercostal spaces into the an- terior mediastinum, to the lymphatic glands in this situa- tion ; while others accompany the intercostal vessels to the posterior mediastinum, or enter directly the thoracic duct. Function. — To secrete the milk designed for the nourish- ment of the infant. The closest sympathy exists between the mammae and the uterus. THE PLEUEA, (Fig. 195.) The pleurae form the interior lining and complete the walls of the chest. They are two in number and consist of complete sacs without any opening, and are reflected from the walls upon the viscera which they enclose. The organs, however, are all on the outside and none within the pleu- ral cavity. Each pleura is one continuous membrane, and can be traced throughout its whole extent. That portion covering the walls is called pleura parietalis or costalis, and that covering the lungs, pleura pulmonalis. The FIG. 194 represents the Lactiferous Ducts. THE PLEURA. 603 FIG. 195. form of each pleura is conical, the apex being above, and their relative situation has been compared to that of two bladders placed side by side, so as to leave a space between them. So with the two pleura, they are situated upon either side of the chest, and approach each other along the median line, having a space between them called the mediastinum. This space is divided into an anterior, middle and posterior, and according to some, also a superior mediastinum, each of which contains dif- ferent organs. By commen- cing on the posterior sur- face of the sternum with either the right or left pleura, we trace this membrane to the front of the pericardium, thence back to the anterior root of the lungs. From the root it is reflected over the anterior sur- face of the lungs, and traced round upon the posterior sur- face to the back part of the root, whence it is reflected to the posterior pericardium, and back to the sides of the vertebrae. From this latter point the pleura stretches all along the spine, ascending as high as the sixth or seventh cervical vertebra, and as low as the diaphragm, Fie. 195 represents the Pleura and its reflections from a transverse section of the chest, a Right lung, b Left lung, c Root of lungs, showing the rela- tion of its vessels. 22 Pulmonary vein. 1 Pulmonary artery. 2 Bronchial tube, d d Reflection of pleura from root of the lung, t Cavity of pleura. / Anterior mediastinum, g Middle mediastinum, containing the heart, h fcavity of the pericardium-, i i Direction of the phrenic nerves, j Aorta, k Vena-azygos. I Thoracic duct, m (Esophagus, w Sympathetic nerve, j k I are in the posterior mediastinum. 604 THE MEDIASTINUM. completely covering this latter muscle, and expanding out- ward from the spine over the ribs and intercostal muscles, forward to the sternum, where the sac was opened and the tracing begun, thus showing one continuous whole through- out. It is thus seen that each pleura forms a vertical sep- tum from the sternum in front to the spine behind, and that the space between these almost parallel partitions is, as just stated, the mediastinum. The anterior mediastinum is immediately behind the ster- num and in front of the pericardium. Its form is triangu- lar, the base being the sternum, the sides are formed by the two pleura, which, approaching each other very closely on the top of the pericardium, constitute the apex. It con- tains much fine cellular structure, some lymphatic glands, and at the superior portion the origins of the sterno-hyoid and sterno-thyroid muscles, with the remains of the thymus gland. This space is exposed by passing up one or two of the fingers behind the sternum from the abdomen, so as to break down the cellular connections between the pleurae, then sawing the sternum longitudinally along the median line, and dividing the cartilages near the sternum. The middle mediastinum contains the pericardium and heart, ascending aorta, superior vena cava, pulmonary ar- teries and veins, and division of the trachea, and is, as its name implies, between the anterior and the next division. The posterior mediastinum, directly behind the middle, and in front of the spine, is exposed by dividing the right pleura in a longitudinal direction behind the root of the lung, and turning the latter over to the left side, when this space will be seen to contain the oesophagus and eighth pair of nerves, the descending aorta, vena azygos, thoracic duct, splanchnic nerves, a quantity of cellular tissue, and several lymphatic glands. A reflection of the pleura from the root of the lung to the diaphragm is called ligamentum latum pulmonis. Structure. — The pleura3 belong to the class of serous membranes, and are thin and transparent, with their internal surface smooth, polished, and free. Their exter- THE LUNGS. 605 nal surface is connected, by cellular tissue, to the ad- jacent parts, having varying degrees of attachment, being with much more difficulty separated at some points than others. The cellular tissue of the pleura is so condensed as to take the form of a fascia, in some places, as on the ribs, where it is strong and more readily detached than on the diaphragm or lungs. On these latter it is so thin and delicate as scarcely to admit of demonstration ; and, though so extremely delicate upon the lungs, it is nevertheless asserted to be strong, resisting, and elastic, and that this transparent fascia can also be dissected off the air-cells. The pleura, then, is really a fibro-serous membrane, and in the healthy state has no perceptible blood-vessels. Function. — To secrete or exhale a serous fluid upon their internal surface, by which the cavity of each pleura is kept in a constantly moist and lubricated condition, thus allow- ing its parietal and visceral portions to glide readily upon each other, and thereby giving both the lungs and walls of the chest the greatest freedom of motion during respi- ration. SECTION II. ORGANS OF RESPIRATION. These comprise the larynx, the trachea, bronchi, and the lungs. The larynx and trachea have already been described in another place ; we therefore proceed to examine the lungs. THE LUNGS, (PULMONES.) The lungs are two in number, right and left, and situ- ated upon either side of the chest, having the mediastinum and heart to separate them. When distended with air, the pleura pulmonalis and pleura parietalis are in close juxta- position; and, strictly speaking, there cannot be said to be any thoracic cavity, as the distended lungs fill the whole space, excepting the small part occupied by the heart and thymus gland. 606 THE LUNGS. The form of the lungs is conical, the apex being above, rounded, and seen to rise from one to two inches above the level of the first rib ; the base below, and concave, to correspond to the convex surface of the diaphragm. The base of the lung presents, from before, obliquely downward and backward, precisely in the direction of the diaphragm, and consequently makes the vertical extent of the lungs behind, which reach from the first to the last rib, much greater than in front, where the extent is only from the first rib to the lower end of the second bone of the sternum. FIG. 196. l-L The size of the lungs is in a direct ratio with the capac- ity of the thorax. The average volume of air they are capable of containing, after an ordinary inspiration, is esti- mated at 140 cubic inches; and after expiration, at 110 cubic inches. From thirty to forty cubic inches is the average estimate of air inhaled at each inspiration. The specific gravity and density of the lungs are less than FIG. 196 represents the Lungs, their anterior surface, with the Heart. 1 The heart — right ventricle. 2 Pulmonary artery. 3 Left bronchus. 4 Vena in- nominata— its junction. 8 Right auricle. 9 Pulmonary vein. 11 Superior lobe of right lung. 12 Middle lobe. 13 Inferior lobe. 14 Superior lobe of left lung. 15 Inferior lobe. THE LUNGS. 607 that of any other organ. This depends on the presence of the air. Their absolute weight is less in the foetus than after birth. In the former the proportion to the body is as one to sixty ; in the latter, as one to thirty. The elasticity of the lungs is very considerable, and it is by this property they are aided in the act of expiration. This property is demonstrated by the collapsing of the lungs on opening the chest. Before the chest is opened, the organs are not collapsed, as the air they contain, by the pressure from within, keeps them constantly dis- tended; but when the chest is opened, the atmospheric pressure from without balances that within, and then the elasticity has the opportunity of exerting its influence, and produces the state of collapse. The color of the lungs varies according to the age. In the foetus it is found to be of a reddish brown, after birth of a light rose or pinkish hue ; in the adult it is grayish, interspersed with black, which presents the form either of lines, patches, or points, and in old age these black deposits increase. The surfaces of the lungs are external and internal. The external is convex and corresponds to the concavity of the rjbs, presenting a variety of different shaped figures sep- arated by intermediate dark lines. The internal is con- cave for receiving the pericardium and heart. The lungs are divided into two lobes by a deep fissure commencing behind and below the apex, and descending obliquely downward and forward to the front of the base. Upon the right lung there is another fissure, which is short, and leads from the middle of the great one forward to the an- terior margin, thus making another lobe for the right lung, which is in the middle, to the other two. The rela- tive position of the two lobes is, the one superior and anterior, the other inferior and posterior. Sometimes the left lung is found with three lobes, and the right with four or more. The anterior edge is short, thin, and oblique. The posterior edge is long, thick, round, and vertical. 608 THE LUNGS. The interlobular surfaces formed by the several fissures entering into the lungs, are all free, smooth, and covered Fig. 197. "by pleura, and increase to an immense extent the area for the cells. Structure, (Fig. 197.) — The different elements constituting the lungs are the bronchial tubes, pulmonary arteries, pul- monary veins, bronchial arteries and veins, lymphatic vessels and nerves, all connected by cellular tissue and covered by pleura. These several tissues before entering the lungs are all collected into a small compass, and known by the name of the root of the lungs. This root is about an inch FIG. 197 represents the distribution of the Bronchise and Blood-vessels, with the relation of the Lungs and Heart. 1 Left auricle. 2 Right auricle. 3 Left ventricle. 4 Right ventricle. 5 Pulmonary artery. 6 Arch of aorta. 7 Superior vena cava. 8 Arteria innominata. 9 Left carotid artery. 10 Left subclavian. 11 Trachea. 12 Larynx. 13 Superior lobe of right lung. 14 Superior lobe of left lung. 15 Right pulmonary artery. 16 Inferior lobe of the lungs. THE LUNGS. 609 and a half long, half an inch wide, and situated upon the internal surface of the lung, a little above its centre. It fixes the lung on either side. The bronchi, or air tubes, (Fig. 165,) form the terminat- ing branches of the trachea, coming off about opposite the fourth dorsal vertebra, and consisting of the right and left bronchus. The right passes beneath the right pulmonary artery to the lung, is about an inch long before dividing, and is larger and shorter than the left. The left bronchus is about an inch longer than the right, though smaller, and passes through the arch of the aorta obliquely downward to the left lung. The right bronchus is embraced at the root of the lung by the vena azygos ; the left by the arch of the aorta. The right, on entering the lung, divides into three branches, the left into two, and both right and left then divide and subdivide into an almost infinitude of branches throughout the lungs. At the bifurcation of the trachea into the bronchia, there is observed a triangular ligament, strong and elastic, occupying the space of separation ; and after entering the lung, the primitive divisions of each bron- chus divide into two, and each one of these again into two, and so on dichotomously as far as they can be traced, the fine tubes ultimately terminating in the lobules, which latter compose the air-cells, and these again consist sim- ply of the dilated terminations of the extended branch- ings of the bronchial tubes throughout the pulmonary structure. Each bronchus, in its primitive division, like the trachea, has its cartilaginous rings deficient in the posterior third. But on entering the lungs, the rings form smaller seg- ments of circles, and consist of small pieces placed equally round the bronchial tubes so as to constitute them cylin- ders. These pieces have different forms, and can overlap and glide upon each other, by means of the circular mus- cular coat, whose fibres are connected with the extremities and margins of these cartilages, and in this way the diam- 39 610 THE LUNGS. eter of these tubes can be diminished, and, as suggested by Dr. Physic, the expulsion of mucus greatly facilitated. These bronchial cartilages, as they proceed, become smaller and smaller till reduced to simple lines, patches, or grains, when they are finally lost and the tube becomes wholly membranous. The cartilages of the bronchi are all connected by a continuation of the same elastic fibrous tissue, that belongs to the rings of the trachea. The extent of the muscular coat of the bronchi is not exactly determined ; some are disposed to think it ceases at the last bronchial cartilage, while others carry it somewhat beyond this point upon the membranous portion towards the cells. The mucous mem- brane of the bronchi is a continuation of the same that lines the trachea and larynx, and is traced on into the air cells of the lungs. It is very vascular, and is seen to present a number of longitudinal folds. This membrane abounds with mucous follicles, whose orifices, upon its surface, are so numerous as to present »the cribriform appearance. At the beginning of the bronchi the mucous coat is found firm, thick, and red. As it proceeds it becomes thinner and paler, till in the membranous terminations it appears transparent and of great tenuity. The Air Cells. — These cells, which are, as just stated, the ultimate coecal terminations of the bronchi, form clusters of cells, constituting the several lobules. Their precise form and arrangement still remain a matter of doubt, for while on the one hand they are regarded by Keisessen and his followers to be round, and related to each other after the manner of the fruit on a bunch of grapes, each grape being connected by a separate pedi- cle to one common stock, so it was thought that the cells of the lobules had no communication directly, but only by their ducts, which lead to a common bronchial tube ; Dr. Horner's experiments seem to show conclusively, on the other hand, that the cells of each lobule communi- cate directly the one with the other, but not with the cells of different lobules; and the terminating bronchial branches, THE LUNGS. 611 which he remarks are about the size of a bristle, and dis- tinctly seen, are supposed to have somewhat the same at- tachment to the lobule and its cells as a blow-pipe fixed to the side of a small piece of sponge. The diameter of these cells is estimated from the l-50th to the l-200th of an inch, and they have no regular shape or size. By a calculation 18,000 of them are made to belong to each lobule, and about six hundred millions to the whole lungs, which will afford some idea of the im- mensity of surface provided for the reception of air, and the ample facilities for purifying the blood by such an arrangement. The pulmonary artery, seemingly the next element in im- portance, comes from the right ventricle of the heart, be- neath the arch of the aorta, and divides into two branches. The one on the right is larger, goes to the root of the right lung, and thence divides and subdivides throughout the substance of this viscus into capillary branches, which are found to terminate upon, and completely surrounding and lining the interior of the air cells. The left pulmonary artery has the same distribution, but is smaller than the right. Both these arteries convey dark, venous blood to the air cells of the lungs, where this impure blood is brought in contact with the air, and the change from dark venous into red arterial blood occurs, a change constituting the great leading object in the function of respiration. The pulmonary veins commence at the air cells, and are formed by fine radicles from the ultimate terminations of the pulmonary artery. These all successively converge into four trunks, two for the right and two for the left lung, which take up the red blood formed in the cells, and convey it into the left auricle of the heart. The bronchial arteries come from the thoracic aorta, fol- low the course of the blood-vessels above mentioned, ramify in every direction, and are designed for the nourishment of the lungs. The bronchial veins return the venous blood into the vena azygos. 612 THE LUNGS. The lymphatics are abundant both on the surface and in the substance of the lungs, and go to the bronchial glands. The nerves come from the pneumogastric and sympa- thetic ; chiefly from the former. A plexus exists on the front and back of the roots of the lungs, called the anterior and posterior pulmonary plexuses. These nervous filaments are traced along the bronchial tubes, forming anastomoses around them, and are supposed to expand themselves upon the mucous membrane and blood-vessels. All these different elements, constituting what is termed the parenchyma of the lungs, are collected and run together in the root, at which point their relation with one another is as follows : after the pleura is removed from the anterior part of the root, we see the pulmonary veins below but in front of the pulmonary artery, — this latter being above and behind the veins, — while the bronchial tube is above and behind the artery. Function. — The function of the lungs or of respiration, is quite a complex act. This act consists in eliminating car- bonic acid from the blood, and supplying its place with oxygen, or, in other words, in converting venous into arte- rial blood. To accomplish this object, a variety of organs are employed. The ribs and intercostal muscles, the dia- phragm, the scaleni, the great and superior serrati muscles, with others, all concur in greater or less degree to enlarge the diameters of the chest, thereby increasing its capacity for the reception of air, and thus accomplishing the act of inspiration. The abdominal muscles, and the posterior inferior serrati, aided by the elasticity of the cartilages, draw down the ribs, and the diaphragm at the same time ascending, the diameters of the chest are diminished, thereby expelling the air from the lungs, and in this way accomplishing the second act of respiration, termed ex- piration. The pneumogastric, intercostal, phrenic and sympa- thetic nerves are essential elements in putting all this machinery in motion, as well as in maintaining it in action. THE THYMUS GLAND. 613 THE THYMUS GLAND. This body is noticed here from being located in the vicin- ity of the thoracic organs, rather than from any thing that is especially known of its physiological relationships. It is situated in the anterior mediastinum, occupying a greater part of its extent. During foetal life, and for the first year or two after birth, it descends in front of the pericardium nearly as low as the diaphragm, and ascends upon the neck as high as the thyroid gland. After the second year it commences diminishing till, at the period of puberty, scarcely a vestige of it remains. Cases, however, are not wanting in which it has been seen at from 20 to 30 years, even larger than in children, and even from 30 to 50 it has been found of considerable size. This body, though called a gland, is destitute of one of the great char- acteristics of a gland proper, an excretory duct. It is a sym- metrical body, consisting of two lobes, of an oblong form, which are connected as well as separated by cellular tissue. Structure. — The lobes of the thymus are divisible into lobules, which, according to the observations of Sir Astley Cooper, consist of vesicles of different sizes connected by cel- lular tissue, which also forms a common capsule to the gland itself. These vesicles or cells communicate with a central cavity or reservoir, which contains a milky fluid, like chyle. This cavity is lined by a vascular mucous membrane, on the surface of which the opening cells are seen. The consist- ence of this gland is soft, and its color of a pinkish hue. Its arteries come from the superior and inferior* thyroid, and internal mammary. Its veins go to the thyroid, and vena innominata. The lymphatics join the absorbents at their junction with the internal jugular and subclavian veins. The nerves are derived from the internal mammary plexus of the sympathetic. Function. — The use of this body is yet unknown, though its great importance to foetal life is admitted by all. Sir A. Cooper suggests that the milk-like fluid found in its cavity is furnished by it for the purpose of nourishing the 614 THE HEART. foetus before birth, as well as for a short time after birth till chylification is fully established. Another opinion entertained is, that it is a diverticulum of blood from the lungs of the foetus, when" these organs, as before birth, are known to be inactive. SECTION III. ORGANS OF CIRCULATION. These organs comprise the heart, arteries, and veins, with the lymphatics, which are regarded as appendages. Under the head of the vascular tissue will be found a general description of the different systems of circulation ; and under the head of organs of absorption will be seen an account of the lymphatics. All that we propose, therefore, in this place, is to confine our remarks to the heart, and great arterial and venous trunks, by giving somewhat more in detail the description of these important organs. THE HEART — (Fig. 10.) The heart, styled the central organ of the circulation, is a hollow muscle. It is situated (Fig. 196) near the cen- tre of the thoracic cavity, in the middle mediastinum, behind the sternum, in front of the vertebral column, be- tween the lungs, and above the diaphragm. Its form resembles that of a cone, and it is divided into a base, body, and apex. Its direction is oblique, from above, on the right, across the spine, downward and forward to the costal ends of the fifth and sixth cartilages, on the left. Its average length, from apex to base, is estimated at about five inches, four of which are given to the ventricles. The base is about four inches. Its weight is from six to eight ounces ; though all these measurements are liable to considerable variation compat- ible with health. The heart is surrounded and kept in its position by a fibro-serous membrane, called the pericardium. This mem- brane forms a conical bag for receiving the heart, and, THE HEART. 615 being much larger than this organ, allows it free motion within its walls. The pericardium consists of two layers, an external or fibrous, and an internal or serous. The fibrous layer is attached below to the cordiform tendon of the diaphragm, to which it is strongly bound by compact cellular substance; laterally it is embraced by the two pleuraB ; in front it corresponds to the anterior, and behind to the posterior mediastinum. Above it is traced upon the great vessels, proceeding from the heart, upon the aorta as high as the arch, upon the pulmonary artery, upon the superior cava for an inch before entering the right auricle, upon the inferior cava, and upon the pulmonary veins. It is prolonged upon the sheath of these vessels, being insensibly lost upon, and becoming identified with their external coat. In structure it is like the dura mater, though thinner. It is also white, inelastic, and semi-transparent. The internal layer of the pericardium is seen by opening this bag, when, like all serous membranes, it presents a smooth, polished, delicate, transparent surface, and forms a shut sack. It lines the interior of the fibrous coat, and is reflected thence upon the great vessels to the heart, whence it is traced over this organ, covering its anterior and posterior surfaces. It is connected to the heart by cellular substance, having frequently interposed a quantity of adipose matter. Function. — The pericardium, by its fibrous coat, is of use in fixing and retaining the heart in its natural position, and preventing over-distention of its several cavities; while, by its serous layer, a fluid is furnished, which both lubri- cates and facilitates the motions of this organ. The heart, as already stated, is a hollow muscle, and contains four cavities, (Fig. 198,) two of which are upon the right side, and anterior, the other two upon the left side, and posterior. The two upon the right being sepa- rated by partitions from those on the left, constitute the heart a double organ, which is distinguished into a right and left heart. Two of these cavities occupy the superior 616 THE HEART. part, forming the base, and are termed auricles. The other two occupy the middle and lower portions, constituting the body and apex, and are called ventricles. 198- The right heart is com- posed of the right auricle and right ventricle, (Fig. 199,) the left heart of a left auricle and left ventricle, (Fig. 200.) The right heart receives venous blood ; the left, arterial blood. We shall examine the heart in the order of its circulation. The blood en- ters first the right auricle, by the superior and inferior vena cava ; from this cavity it passes into the right ventri- cle, through the ostium venosum. From the right ventri- cle it goes to the lungs, by the pulmonary artery. From the lUngs it returns to the left heart by the four pulmonary veins, entering at the left auricle. From the left auricle it goes through the ostium arteriosum into the left ventricle ; and from the left ventricle it passes out by the aorta, to be distributed to all parts of the body. Eight Auricle. — Make an incision from the superior to the inferior cava, and cross it by another running trans- versely along the centre of the cavity. On washing out the blood there is seen, at the upper and posterior part, the 'superior vena cava, descending obliquely forward and FIG. 198 represents the Cavities of the Heart, a Right auricle, b Superior cava — its entrance, c Inferior cava — its entrance, d Entrance of coronary vein, partly closed by valve, e Eustachian valve. / Fossa ovalis. g Tuber- culum loweri. h Musculi pectinati. i Right auriculo-ventricular opening, or ostium venosum. j Right ventricle, k Tricuspid valve. I Chordae-tendi- neae, and carneae column®, m Pulmonary artery — its three semi-lunar valves, seen at its commencement, n Right pulmonary artery, o Left pulmonary artery, p Left auricle, q Openings of the four pulmonary veins, r Left auriculo-ventricular opening, or ostium arteriosum. s Left ventricle, t Mi- tral valve, it Aorta — its commencement and semi-lunar valves, v Arch of aorta. THE HEART. 61? inward, about an inch within the pericardium, to enter the auricle. There is no valve at the entrance of this vein. At the lower portion of the auricle the inferior cava is seen to enter FIG. 199. obliquely hack- ward and in- ward, ascend- ing within the pericardium onl y for a short distance. At the en- trance of this vein there is a valve, called the valve of Eus tachius, which, in the adult, is very imperfect, but in the foetus is quite large, and, according to Sabatier, is obviously designed to conduct the foatal blood to the foramen ovale, and prevent the mix- ing of the superior and inferior ^streams. This valve is formed by a doubling of the lining membrane of the auri- cle, surrounding about one half of the front of the inferior cava, and stretching between this vessel and the fossa ovalis, with which it is connected. Between the two cava, about midway, is seen a transverse prominence, called tuberculum Loiveri. The direction of the blood, entering the auricle by these two veins, is such' FIG. 199 represents the right Heart laid open. 4 Superior cava. 8 Its entrance into right auricle. 18 Inferior cava — its entrance into the right auricle. 13 Smooth portion of right auricle. 14 Eustachian valve. 15 mus- culi pectinati. 9 Fossa ovalis, or remains of foramen ovale. 19 Annulus ovalis. 22 Opening of coronary vein. 1 Cavity in right ventricle, leading to the pulmonary artery. 11 Pulmonary artery. 12 Septum between ventricles. 3 Tricuspid valve. 6 Aorta. 618 THE HEART. says Mr. Wilson, that a stream forced into the superior, takes a course towards the ostium venosum, or right au- riculo-ventricular opening — while the inferior current is directed to the septum auricularum, or fossa ovalis, the natural course of the blood in the foetal state. The outer and posterior walls of the auricle are dilated into a pouch called its sinus, while the superior projecting extremity, with indented edges, from its resemblance to the ear of the dog, gets the name of auricle. This portion, together with the sinus, has a number of fasciculi of muscular fibres running parallel to each other, and called, from their resemblance to the teeth of a comb, musculi pectinati. Between these fasciculi the spaces con- tain no muscular fibre. The internal wall of this cavity consists of a thin parti- tion called the septum auricularum, which separates it from the left auricle. On the lower part of this septum a de- pression is seen, the fossa ovalis, the margin of which all round is thick and elevated, and termed annulus ovalis. This fossa ovalis corresponds to the opening in the foetus called foramen ovale, through which the blood passed freely and directly from the right auricle to the left, but which, after respiration is established, becomes closed by the sep- tum just mentioned. To the left of the Eustachian valve is seen an orifice about the size of the common quill ; this is the opening of the coronary vein of the heart, and is protected by a semi- lunar valve called the valve of Thebesius, which is formed by a duplication of the lining membrane of the auricle, and prevents the blood from regurgitating into the vein. At different points of the auricle, small orifices are seen, called foramina TJiebesii, some of which are regarded as the terminations of veins, while others simply lead into the muscular depressions. Eight Ventricle. — The passage from the right auricle into the right ventricle is through a large, round opening, the ostium venosum or right auriculo-ventricular opening. A dense white line, termed the right tendon of the heart, THE HEART. 619 surrounds this opening. By making one incision along the right side of the heart, and another along the septum cordis, and turning up a flap from below, this cavity will be exposed. Its form is triangular, with the base above and connected with the auricle, while its lower extremity stops a little short of the apex of the heart. The right ventricle occupies the anterior and right side of the heart, and has its walls much thicker than those of the auricle, being estimated about three lines, while the latter is but one line. Its interior surface is very irregular from numerous muscular fasciculi called columnce carnece. These fleshy columns are differently arranged ; some are connected along their whole length ; others are fixed by their ex- tremities ; while others again are only attached by one extremity, having the other free, to which is connected several round, tendinous chords called chordae tendinece. These chords interlace among themselves, and are, with the valve, placed between the right ventricle and auricle. This valve is formed by a fold of the lining membrane projecting from the auriculo-ventricular opening, and, from being divided into three pieces, is called tricuspid. One of these pieces is posterior, on the septum cordis ; a second is anterior and the largest, separating the auricu- lar from the pulmonary arterial orifice, while the third is to the right side. This valve prevents the blood, during the contraction of the ventricle, from returning back into the auricle, which is done by the columnar carneae con- tracting, and putting upon the stretch the chordae tendineaa, which draw the several pieces of the tricuspid to each other, while at the same time the blood gets behind, and thus assists to approximate as well as support them, and prevent their being forced open. At the superior and left extremity of the right ventricle, is seen the orifice of the pulmonary artery. This orifice is smooth and round, about an inch in diameter, and protected by three valves, termed semilunar or sigmoid. These valves are formed by a duplication of the lining membrane of the 620 THE HEART. artery, being connected to the latter by their circumference, and having, in the centre of each loose edge, a little white or yellowish body called corpusculum Arantii. These cor- puscles serve as abutments to support each other when the valves are brought together, and thus prevent the blood from regurgitating. Exterior to these valves, and between them and the artery, are three pouches called the sinuses of Valsalva. The pulmonary artery ascends obliquely backward to the under part of the arch of the aorta, where it divides into two branches, one for each lung. The right is both longer and larger ; it goes behind the aorta and superior cava to the root of the right lung, where it divides into three branches. The left is shorter, and goes in front of the descending aorta to the root of the left lung where it divides into two branches. The distribution of these branches has been already given in the description of the lungs. Where the pulmonary artery divides into its right and left branches, a ligamentous cord is seen to extend backward and downward to the lower extremity of the arch of the aorta. This, in the foetus, was an open tube called the ductus arteriosus, through which passed to the aorta the balance of the blood which failed to go through the foramen ovale, the pulmonary arteries carrying to the lungs only so much as was just sufficient for their nutrition. Left heart, (Fig. 200,) — Left auricle. — The pulmonary veins, four in number, two from each lung, return the blood, after it has been changed from venous into arterial, into the left auricle. This auricle is situated at the superior and back part of the base of the heart, being hid by the ventricles and right auricle. Its shape is more of a square than the right, and it has a pulmonary vein entering each of its angles. It consists, like the right, of a sinus and appen- dix. Its walls are thicker and stronger than those of the right auricle, though its cavity is smaller. Its appendix contains ihemusculipectinati, and is more indented, crooked and narrower, than that of the right. At the inferior part of this auricle is seen the opening into the left ventricle, THE HEART. 621 called ostium arteriosum, or the left auriculo-ventricular opening. Left ventricle. — This cavity presents a conical form, and is posterior to the right ventricle. Its "base is above, and apex, which is below, projects be- yond the right, and consti- tutes the apex of the heart. Its walls are about three times as thick as those of the right ventricle, and it has the same arrangement of columnce carnece and chor- dce tendinece, as the right, only thicker and stronger. The partition between the two ventricles is styled the septum cordis. It con- sists of a thick muscular wall, formed mostly by the left ventricle. At the upper and back part of this cavity the left auriculo-ventricular opening is seen, and is found to be protected by a fold of the lining membrane projecting from round the margin of this orifice into the ventricle, and dividing into two portions, called the mitral valve. The margin of this opening consists, as in the right, of a white and dense tendinous structure. The anterior division of the mitral valve is larger and broader than the posterior, and covers, in a great measure, the aortic opening. This valve, as well as the tricuspid, contains the fibrous structure, is attached by tendinous chords to the columna? earner, and serves to prevent the reflux of blood into the auricle. The orifice of the aorta is seen in front of the auricular opening, #nd, like that of the pulmonary artery, is guarded FIG. 200 represents the left Ventricle laid open, a Parietes of left ven- tricle. 6 Its cavity, c Mitral valve, d Chorda? tendineae. e Columnse carneae. / Right auricle, g Left auricle, h h Four pulmonary veins, i Aorta . j Pulmonary vein. 622 THE HEART. by three semilunar valves, having the same provision of corpuscula Arantii and sinuses of Valsalva, but larger and stronger, and having a similar function of preventing the reflux of the blood. The capacity of the different cavities of the heart is very nearly the same, and is estimated at about two ounces. Structure. — Several elements enter into the composition of the heart. There is first and most external, the reflected serous layer of the pericardium, covering the whole of the outer surface, and already described. On the inner surface, and lining the auricles and ventricles, is seen a very deli- cate and transparent serous membrane, called the endocar- dium. It is strongly attached to the muscular fibres of the columnaa carnese and musculi pectinati, filling up their in- terstices, rendering smooth the whole interior surface of the several cavities, and by its duplications forming the differ- ent valves found between the auricles and ventricles, and at the mouths of the aorta and pulmonary artery. Between the outer and inner membrane is situated the muscular structure. This is the most abundant and im- FlG 201. portant element of the heart. Its fibres are difficult to trace, and it is advised to submit them to boiling, maceration, putrefaction, and hardening in alcohol, as some of the necessary preparatory means to a suc- cessful dissection. Accord- ing to Cruveilhier, this ele- ment of the ventricles "is composed of two muscular sacs, contained within a third, which is common to both ventricles/' All- the mus- FIG. 201 represents the spiral course of the muscular fibres of the Heart, chiefly those of the left ventricle. 1 Left ventricle. 2 Right ventricle. 3 Septum of the ventricles. 4 Muscular fibres making a spiral turn around. 5 The apex. THE HEART. 623 cular fibres are traced to the fibrous zones or tendinous circles of Lower, which are situated at the auriculo-ventricu- lar, and arterial orifices, and constitute the frame-work of the heart. These fibres are divided into the superficial or common, and deep or reflected. The superficial are traced from the base of the heart, taking a spiral course to the apex — those on the anterior portion going from right to left, and those on the posterior from left to right, meeting and decussating at the apex. From this latter point, where they turn round upon themselves, they are reflected upward, and constitute the deep layers. Those belonging to the ante- rior superficial set form, by their reflection, the deep layer of the posterior wall, while those of the posterior superfi- cial set constitute the deep layer of the anterior wall. Be- tween these two sets, an intermediate one, called the proper fibres of each ventricle, is seen. They are compared to a small barrel or truncated cone, their superior openings corresponding with the orifices between the auricles and ventricles, while their inferior are observed to leave two considerable spaces, which are simply occupied by the com- mon fibres. This accounts for the apex of the heart being- weaker than any other portion of the ventricles. The muscular fibres of the auricles are also divided into a superficial and deep set. The former, the fibres common to both auricles, occupy their anterior surface, and run transversely from right to left. The deep set, or proper fibres form a uniform circular layer. Some of them are also oblique, and constitute a muscular sphincter round the several orifices of the auricles. The muscular layer of the right auricle is not so uniform and continuous as that of the left. The septum of the auricles also contains muscu- lar fibres, which form a ring round the fossa ovalis. At the septum of the ventricles, the right and left hearts are capable of separation, if carefully done. The arteries of the heart come from the aorta, and are the first branches given off at its origin. They are the right and left coronary. 624 THE HEART. The right coronary artery arises above the anterior semi- lunar valve in front of the aorta, makes its appearance "between the right auricle and ventricle, and following the course of the groove between these two to the posterior part, distributes branches as it proceeds to the right auricle and right ventricle. The left coronary artery comes from above the left semi- lunar valve, and, while concealed by the pulmonary artery, divides into two branches, a superior and inferior. The superior passes round the groove between the left auricle and left ventricle to the back of the heart, and supplies these two cavities with branches. The inferior division descends along the septum of the ventricles to the apex of the heart, supplying with branches both ventricles, and anastomosing freely with the other coronary branches. The coronary veins return the blood of the heart, and are distinguished into the greater and lesser coronary. The greater coronary vein begins at the apex of the heart, by the union of several branches, and then ascends along the an- terior septum of the ventricle, to terminate finally in the right auricle, at its posterior inferior part, to the left of the inferior cava, where it is guarded by a valve. Throughout its whole course it is constantly receiving streams. The lesser coronary vein returns the blood, mostly of the right ventricle, and discharges it into the greater coronary just as the latter is entering the right auricle. Some smaller veins are also described about the roots of the aorta and pulmonary artery, discharging into the right auricle by several orifices. The nerves of the heart come principally from the cardiac plexus of the sympathetic, and follow the course of the coronary arteries. Branches also are traced from the par • vagum. Function. — The office of the heart has already been stated to be, to circulate the blood, in which function it is the prime agent. The venous blood is returned from all parts of the body by the ascending and descending cava, and coronary vein, into the right auricle of the heart. This THE HEART. 625 auricle, by its muscular apparatus, contracts, and throws the blood through the ostium venosurn, into the right ven- tricle. This ventricle now contracts and propels the blood into the pulmonary artery ; the tricuspid valve preventing its return into the auricle. The pulmonary artery con- ducts the blood to the air cells of the lungs, where it is changed from venous into arterial,, as already explained under the head of respiration, and its return to the ven- tricle is prevented by the semilunar valves placed at the mouth of the artery. From the lungs it is carried by the four pulmonary veins to the left side of the heart, into the left auricle,, thus completing a circle from the right to the left auricle, called the pulmonic or lesser circulation. The left auricle now contracts and throws the blood through the ostium arteriosum, into the left ventricle, which in turn contracts and propels it into the aorta ; the mitral valve between the auricle and ventricle, and the semilunar valves at the mouth of the aorta, preventing any regurgi- tation. From the aorta it passes to every part of the sys- tem, returning by the vena cava to the right side of the heart, and thus completing another circle called the systemic or greater circulation. In the passage of the blood through the heart, two dis- tinct sounds are heard, known as the sounds of the heart. The first sound is dull, prolonged, and corresponds with the contraction of the ventricles, and the impulse of the heart against the ribs. The second sound, compared to a click, is sharp, clear, and quick, and corresponds to the diastole of the heart. The two sounds embrace one arterial pulsation. The two auricles contract synchronously, so likewise the two ventricles. The first sound, it is believed, results from the contraction of the muscular fibres of the ventricles, the impulse of the heart's apex against the ribs, and the rush of the blood through the aorta and pulmonary artery. The second sound is thought to arise from the sudden filling and quick closure of the semilunar valves, by the reflux of the blood during the diastole of the ventricles, and the recoil of the elastic coat of the arteries ; other opinions are enter- 40 626 THE AORTA. tained in reference to the origin of these sounds, which it is not thought necessary to notice further in a work like the present. THE AORTA, (Fig. 8.) The origin, course, and termination of the aorta, together with a general outline of its primary and prominent sec- ondary branches, will he found under the head of the vas- cular tissue. A detail of the several branches, supplying the various organs contained in the cranial, abdominal, and thoracic cavities, the exceptions hereafter to be no- ticed, have also been given in connection with the exam- ination of each of these organs. So that all we propose, in the present place is, a brief recapitulation of the primary branches of the aorta, in the order in which they suc- cessively arise from this tube, and the organs and vis- cera to which they are respectively distributed, so as to fix, more firmly in the memory, the chain of connection between these two great classes of organs, and their relative dependency. The aorta, it is known, comprises the great trunk or arterial half of the general or systemic circulation. Com- mencing in the upper portion of the left ventricle of the heart, concealed by the pulmonary artery, it ascends to the right side, on a level with the second rib and its cartilage; then crosses behind the sternum, about an inch below its upper edge, to the left side, when it turns downward and inward to the third or fourth dorsal vertebra. To this point a curvature is described, constituting the arch of the aorta, which consists of an ascending, transverse, and de- scending portion. From the arch, the aorta continues descending upon the left side of the vertebral column, through the thoracic cavity, to the diaphragm, to which point it is called thoracic aorta. Passing beneath the crura of the diaphragm, it enters the abdomen and traverses this cavity upon the median line, to the space between the fourth and fifth lumbar vertebras, where it terminates by dividing into the common or primitive iliac arteries. THE VENA CAVA. 62f This portion is styled the abdominal aorta. The first branches given off by the aorta, are those supplying the heart, and consist of the right and left coronary. The next branches in order are those coming off from the arch, and are the arteria innominata, the left carotid, and the left sub- clavian, which supply the neck, head, upper extremities, and part of the wails of the chest. The branches of the thoracic aorta (Figs. 8 and 214) come next, and consist of the bronchial arteries, which go to the lungs ; the cesophageal, five or six in number, to the oesophagus ; the posterior mediastinal to the mediastinum ; and the intercostal to the intercostal spaces and walls of the chest. The superior intercostal comes from the sub- clavian. All these arteries are in pairs. The abdominal aorta, (Figs. 8 and 214,) the last portion of this tube, gives off the phrenic to the diaphragm. The cceliac, a single trunk, divides into three branches — the gastric, hepatic, and splenic, which go to the stomach, liver, and spleen. The superior mesenteric artery, about an inch below the coeliac, supplies the small intestines, the right ascending, and transverse portion of the large intestine. The emulgent or renal arteries, two in number, come off at right angles, and go to the kidneys. The spermatic, long and small, descend to the testicles. These are sometimes branches of the renal. The inferior mesenteric, a single trunk, supplies the left colon and rectum. The lumbar arteries are in pairs, from three to five in number, and supply the abdominal walls. THE SUPERIOR AND INFERIOR VENA CAVA, (Fig. 9.) These two great veins, called also the ascending and de- scending cava, with the coronary, return all the blood of the body, and constitute the venous portion of the systemic or general circulation. The descending or superior cava returns to the right auricle of the heart all the blood of the body from above the diaphragm. 628 THE VENA AZYGOS. The sinuses of the brain, emerging at the base of the cranium, become the internal jugular veins, which, with the external jugulars, descend the neck, and at the root of the latter unite with the subclavian upon either side, and form the right and left vena-innominata, the junction of which, behind the cartilage of the first rib upon the right aide, constitutes the superior cava. This great vein is about three inches in length, and de- scends within the pericardium to enter the upper portion of the right auricle. It has in front of it the remains of the thymus gland and some cellular structure ; behind is the right pulmonary artery and the pulmonary vein ; upon the right is the phrenic nerve and right lung ; upon the left or internally is the ascending aorta. Just as it enters the pericardium it receives at its posterior part the vena azygos. The vena azygos (Fig. 9) returns the blood chiefly of the parietes of the chest. It commences in the abdomen, op- posite the second lumbar vertebra, by branches from the superior lumbar veins, and sometimes also from the renal and spermatic, with an occasional branch from the inferior cava. Thus formed, it ascends through the aortic opening in the diaphragm to the thorax, and continues upward in the posterior mediastinum upon the right side of the verte- bral column, having the thoracic duct and aorta upon its left, and the splanchnic nerve upon its right. It increases in size as it ascends, and about the fourth dorsal vertebra arches over the root of the right lung to terminate in the superior cava, where a valve~Ms found to prevent regurgita- tion. This vein in its course receives the intercostal veins of the right side, the azygos minor or vena Jiemiazygos of the left side, which is formed from the superior left lumbar veins, *nd as it ascends receives the six or seven left infe- rior intercostals. It crosses the spine about the sixth or seventh dorsal vertebra behind the aorta and thoracic duct, and joins the right or great vena azygos. The five or six left superior intercostal veins constitute what has been NERVES OF THORAX AND ABDOMEN. 629 called a superior vena azygos, which empties into the left vena innominata, and connects also with the lesser azygos. The vena azygos also receives the bronchial, cesophageal, and mediastinal veins. The inferior or ascending cava (Fig. 9) returns all the blood of the body from below the diaphragm. The two primitive or common iliac veins, formed by the junction of the external and internal iliacs at the sacro-iliac articula- tion, converge upon the right side, and unite upon th& ligament between the fourth and fifth lumbar vertebrae to constitute the commencement of the ascending cava. This great vein now ascends upon the right side and partly in front of the spinal column, on the right psoas muscle, and right crus of the diaphragm, havinsj the aorta upon the left — enters the fissure in the posterior part of the liver, and ascends through the tendinous opening in the diaphragm, to which it strongly adheres, to terminate in the inferior and back part of the right auricle. In its course it receives the lumbar, renal, spermatic, phrenic, and hepatic veins. The veins of the stomach, pancreas, spleen, and intes- tines, go to form the great portal vein, which is described under the head of the vascular tissue. NERVES OF THE THORAX AND ABDOMEN. These nerves comprise the sympathetic, the thoracic spinal, the lumbar spinal, pneumogastric, and phrenic. The sympathetic in the chest (Fig. 155) consists of twelve dorsal ganglia with their several branches. The ganglia are situated upon the heads of the ribs, covered by the pleura costalis and a thin fascia. Their form is triangular and flat, the apex external, and the base, looking to the spine. They are small, and present the usual gray color and pearl v lustre of the rest of the ganglia composing *the sympathetic system. They are connected above and below to each other by branches called superior and inferior. The other branches are external and internal. The external branches, two and sometimes more, or onlj 630 SYMPATHETIC NERVE. one in number, pass obliquely upward and outward to join the corresponding spinal nerve, though a twig is sometimes sent to the intercostal FIG. 202. mediastinum, following nerve below. The in- ternal branches consist of the mediastinal and splanchnic. The for- mer enter the posterior the course of the inter- costal arteries to the aor- ta on both of which they ramify in the form of plexuses. Other branch- es are traced upon the oasophagus, the longus colli muscle, and into the cardiac and pulmonary plexuses. The splanchnic nerves are divided into the great and less. The great splanchnic comes from the sixth, seventh, eighth, ninth and tenth ganglia, by several distinct roots. These descend obliquely upon the sides and front of the dorsal vertebrae, to about the tenth or eleventh, where they unite into a common trunk, which is large and passes through the diaphragm either by piercing it, or along with the aorta to terminate in the semilunar ganglion. The lesser splanchnic derives its roots from the tenth and eleventh ganglia. These roots, uniting, enter the abdomen through the crus of the diaphragm, external to the great splanchnic, and go to the renal plexus. The sympathetic nerve in the abdomen (Fig. 155) com- prises the semilunar ganglion and its various plexuses, with the lumbar ganglia. The semilunar ganglion is situated upon either side of the coaliac artery, and by some is regarded as the grand FIG. 202 represents the connection of the Sympathetic Nerve with the Spinal, a a Anterior fissure of the spinal marrow 6 Motor or anterior root of the spinal nerve, c Posterior root, d Ganglion on the posterior root. // Spinal nerve, e Its posterior branch, g Its anterior hranch. h h Two tho- racic ganglia of the sympathetic, i Sympathetic trunk connecting the ganglia. j fc Two filaments uniting the sympathetic and spinal nerve. SYMPATHETIC NERVE. 631 centre of the sympathetic system. It consists of a series of ganglia, more numerous on the right than the left side, about an inch in length and presenting a semicircular form; several of these are sometimes fused into one. They all communicate and send off an immense number of radiating filaments, constituting the solar plexus. This plexus (Fig. 203) is situated behind the stomach, above the pancreas, and within the epigastric region, and receives branches from the lesser splanchnic, the phrenic, and the right vagus. From this central and great plexus, nervous filaments proceed in every direction, and mostly follow the course of the arteries, around each of which they form a plexus, receiving its name from the artery it accom- panies. Thus we have enumerated the following different plexuses : The phrenic, composed of branches coming from the solar plexus, accompanies the phrenic arteries to the dia- phragm. The gastric plexus goes along the coronary artery to the stomach, where it communicates with the vagi. The hepatic plexus takes the course of the hepatic artery to the liver. Branches also accompany the vena portaa and right gastro-epiploic artery to the greater curvature of the stomach. The splenic plexus follows the splenic artery to the spleen, sending off branches to the pancreas and head of the stomach, and along the left gastro-epiploic artery to the greater curvature of the stomach. The superior mesenteric plexus surrounds the superior mesenteric artery, and its branches supply the small in- testines, co3cum, ascending, and transverse colon. The renal plexus attends the renal arteries to the kid- neys. This plexus gives off filaments to the supra-renal capsules, called supra-renal plexus , and also filaments along the spermatic artery, called the spermatic plexus, to the testes of the male, and ovary of the female. The inferior mesenteric plexus follows the course of the inferior mesenteric artery, and supplies the descending 632 SYMPATHETIC NERVE. FIG. 203. and sigmoid flexure of the colon. It sends off filaments called the hcemorrhoidal plexus, which follow the heemor- rhoidal arteries to the rectum. The lumbar ganglia are four or five in number, situated upon the bodies of the lumbar vertebras, and connected with the thoracic by a cord which descends be- hind the diaphragm close to the spine to join the first lumbar ganglion. These ganglia also send off external and internal branches. The external communicate by two or three branches with the lumbar nerves. The in- ternal surround the aorta, forming the Aortic Plexus. — This plexus receives filaments from the inferior mesen- teric, and descends into the pelvis, where, in front of the sacrum, it forms the hypogastric plexus. This latter plexus com- municates with the sacral, and sends filaments to the pelvic organs, which will be noticed in another place. The thoracic spinal nerves (Fig. 14) are twelve in num- Fio. 203 represents the plexuses of the Sympathetic Nerve. I Dorsal gan- glia of the sympathetic, with the roots of the great splanchnic nerve arising from them, m Lesser splanchnic nerve, o Solar plexus. « Renal plexus. p Mesenteric plexus, q Lumbar ganglia, r Sacral ganglia, s Vesical plexus. t Rectal plexus, u Lumbar plexus (spinal.) v Rectum, w Bladder. * Pubis. y Crest of ilium, z Kidney, o o Aorta. 6 6 Diaphragm, c c Heart and cardiac plexus, d d Larynx. THORACIC SPINAL NERVES. 633 ber on each side. They arise by filaments from the ante- rior and posterior root of the spinal marrow, and pass out through the intervertebral foramina ; each nerve then divides into an anterior and posterior branch. The ante- rior branches occupy the intercostal spaces, pursue the course of the intercostal arteries, and are called the intercostal nerves. Each receives two branches from the thoracic ganglia of the sympathetic, and then runs along the groove on the under margin of each rib, between the two laminae of the intercostal muscles. The five or six upper intercos- tal nerves pass round to the sternum, and when near the latter, emerge from between the intercostal muscles, and are distributed upon the pectoral muscles and integuments. The five or six lower nerves supply the abdominal muscles and their integuments. The first anterior thoracic nerve joins the last cervical, and sends a branch on the inner face of the first rib, which goes to supply the intercostal muscles. The second ante- rior thoracic, or dorsal nerve, in addition to the ordinary distribution, sends a branch between the ribs, which passes outward to the axilla, there joins the internal cutane- ous of the upper extremity, and then descends the arm, distributing filaments upon the integuments as far as the elbow. The third anterior dorsal also sends a branch to the axilla, which supplies the integuments on the inner side of the arm. These nerves are called intercosto-humeral, or the nerves of Wrisberg, and are supposed to explain the numbness of the arm in angina pectoris. The lower intercostal nerves, about the middle of the ribs, send off branches, called external pectoral, which are spent upon the muscles and integuments upon the side of the chest. The continued nerve, which is the intercostal proper, emerges, as already stated, near the sternum, and supplies the pectoral muscles, mamma, and integuments on the front of the chest. The posterior branches of the dorsal spinal nerves are smaller than the anterior. They pass backward between the corresponding transverse processes of the vertebrae, 634 ABDOMINAL SPINAL NERVES. FIG. 204. and divide into external and internal branches. The for- mer supply the longissimus dorsi, sacro-lumbalis, trape- zius, rhomboid, latissimus dorsi, and adjacent integu- ment. The internal supply the multifidus spinae, the long muscles of the back, and can likewise be traced to the integuments. The abdominal spinal, or lumbar nerves. — These consist of five pairs, and are larger than the dorsal. They pass through the intervertebral foramina, the first pair between the first and second lumbar vertebras — the fifth between the last vertebra and the sa- crum. Like the dorsal, these nerves consist of anterior and posterior branches. The anterior are the largest, and pass through and behind the psoas magnus, uniting with each other to con- stitute the lumbar plexus. The first lumbar unites with the last dorsal. The lumbar plexus is concealed by the psoas magnus muscle, and is situated upon the sides of the lumbar verte- brae in front of their transverse processes. The branches of this plexus are divided into the super- ficial and terminal. The superficial are again divided into the abdomino-crural and genito-crural, and consist, accord- FIG. 204 represents the Lumbar and Ischiatic Plexuses, a Lumbar plexus. . 6 Ischiatic plexus, c c Abdominal crural nerves, d External cutaneous nerve, e f g Cutaneous branches from h Anterior crural nerve, i Genito- crural. j j Termination of the sympathetic, k Iliacus internus muscle. I Broad muscles of the abdomen, m Psoas magnus. n Bodies of lumbar verte- bra, o Quadratus lumborum. p Diaphragm, q Sartorius muscle. ABDOMINAL SPINAL NERVES. 635 ing to Bichat, of the superior, middle, and inferior musculo- cutaneous. The superior musculo-cutaneous (called also external ilio- inguinal, ilio-liypogastric, ilio-scrotal) conies from the supe- rior part of the plexus, passes outwardly through the psoas inagnus to the quadratus lumborum, and thence to the back part of the crest of the ilium, — here it divides into an external and internal branch. The former supplies the ab- dominal muscles and integuments. The internal can be traced forward to the anterior superior spinous process of the ilium, and thence across parallel with Poupart's liga- ment to near the rectus, where it perforates the external oblique, and becomes cutaneous upon the pubic and ingui- nal regions. The middle musculo-cutaneous , or inguino-cutaneous , has nearly a similar origin and distribution with the last. The inferior musculo-cutaneous, or external cutaneous , comes from the first or second lumbar, passes along the iliacus muscle, and between the anterior superior and an- terior inferior spinous processes, divides into an anterior and posterior branch. The former perforating the fascia lata about three or four inches below Poupart's ligament, be- comes cutaneous, distributing filaments as low as the knee. The posterior is spent on the outer and back part of the thigh, either passing through or behind the tensor vaginse femoris. The genito crural comes from the second or third lumbar nerve. The genital or spermatic branch joins the cord at the internal ring, supplies the cremaster, and terminates upon the integuments of the scrotum and pubis, and in the female upon the labium. The crural goes beneath Poupart's liga- ment, pierces the sheath of the femoral vessels, sending some filaments in company with the artery, passes through the fascia lata, and supplies the integuments upon the front of the thigh as far as its middle. The terminal branches of the lumbar plexus are the ante- rior crural, obturator, and lumbo-sacral. The anterior crural (or femoral nerve) comes from the 636 ABDOMINAL SPINAL NERVES. superior lumbar nerves, and is the largest nerve of the lum- bar plexus. It passes behind, and sometimes through the psoas muscle, and descends to Poupart's ligament, beneath which it passes about half an inch to the outside of the femoral artery, where it divides into numerous muscular and cutaneous branches. In the pelvis it distributes fila- ments to the psoas and iliac muscles. The obturator nerve comes from the third or fourth lum- bar, passes through the psoas muscle, and descends along the inner edge of the latter to the obturator foramen, through which it passes to the inner side of the thigh, where it divides into an anterior and posterior branch, which supply the muscles chiefly on the inner thigh, the adduc-. tors, gracilis, vastus internus, &c., as well as the integu- ments, and anastomoses with the vaginal branches of the crural ; one long branch is traced as low down as the po- piteal space, to the back part of the knee joint. The lumbo-sacral nerve comes from the fourth and fifth lumbar, and descends into the pelvis to join the sacral plexus. The posterior divisions of the lumbar nerves pass back- ward between the transverse processes, and supply the multifidus spinae, longissimus dorsi, and sacro-lumbalis muscles, and the integuments. Varieties will be seen in the number and distribution of the branches of the lumbar plexus. The sacral nerves (Fig. 204) consist of six pair. They divide within the spinal canal into anterior and posterior branches, which pass out at the anterior and posterior sacral foramina. The posterior are quite small, and supply the muscles and integuments on the back of the sacrum. The anterior are large, the four superior of which, with the last lumbar uniting together, constitute the sacral plexus. These nerves all receive branches from the sacral ganglia of the sympathetic. The fifth and sixth are very small, sometimes absent, and escape between the sacrum and coccyx The sacral or sciatic plexus is situated upon the side of THE KIDNEYS. 637 the rectum, in front of the pyriformis muscle, and behind the pelvic fascia. Its branches are divided into internal and external. The former are distributed to the pelvic viscera, the latter, consisting of the greater and lesser ischiatic, glu- teal, and pudic, go principally to the lower extremity. All of these will be noticed in connection with the organs they severally supply. CHAPTEK V. ACTIVE ORGANS OF THE TRUNK. FOURTH DIVISION. THE ORGANS OP URINATION. THESE organs consist of the Kidneys, the Ureters, and the Bladder. SECTION I. THE KIDNEYS. The kidneys are two firm, solid bodies, situated in the lumbar regions, at their, posterior portion, extending be- tween the crest of the ilium and the last rib — lying upon the psoas magnus, quadratus lumborum, and diaphragm, and corresponding to the two last dorsal, and two upper lumbar vertebrae. Their form is that of the kidney-bean. Their size is about four inches in length, and two in width. Their average weight is estimated at from three to four ounces. Their color is a dark, brownish red. The anterior surface of each kidney is convex, the right having the ascending colon and duodenum upon it; the left the descending colon, and both of them the peritoneum upon this same surface. The posterior surface is flat. In the foetus both surfaces present the lobulated appearance. The outer margin is smooth and convex ; the inner presents a notch, hilus renalis, where the vessels and nerves enter and pass out. The upper end of each kidney is larger, 638 THE KIDNEYS. rounder, and nearer the spine, than the lower end, and is also surmounted by the renal capsule. The kidneys are seen to vary in number, sometimes there FIG. 205. being only one, which is quite large, and ex- tending across the spine. The two kidneys are sometimes con- nected by a transverse band, and Dr. Homer cites an instance where one of the kidneys was in the pelvis in front of the rec- tum. The kidneys are essentially glandular or- and each consists of membranes,, two distinct sub- stances, the cortical and tubular, the excretory ducts, blood- vessels and nerves. Three membranes are given to the kidney, a serous, cel- lulo-adipose, and fibrous. The first comes from the peri- toneum, and is partial, covering only the anterior surface. Of the second, or celMo-adipose, the cellular portion prevails in the young, while the adipose is most abundant in the adult. The third orfbrous is the proper coat of the kidney. It forms a capsule which completely envelops the surfaces, and enters the hilus along with the blood-vessels. This membrane, as already stated, is fibrous, and is also strong, elastic, smooth, and semi-transparent. It adheres to the sur- FIG. 205 represents the Urinary Apparatus, a a Kidneys. 6 6 Capsulae renalis. c c Ureters, d Bladder, t Rectum. / Renal arteries, g Aorta. h Its division into the iliacs. t Point where ureters cross the iliacs. THE KIDNEYS. 639 face of the kidney by delicate cellular and vascular fila- ments, which are easily torn on raising it, and which are traced into its substance. It preserves the form of the kidney. On making a section of the kidney from its convex to its concave portion, two distinct substances are noticed, the external or cortical, and the internal or tubular. The cortical forms the superficial layer, is about FIG. 206^ two lines in thickness, though vary- ing at different points, and sends pro- cesses towards the centre of the gland between the tubular portion, thus dividing the latter into as many separate parts assuming the form of distinct cones. Its color is a reddish brown, and it is also called vascular from the quantity of blood-vessels ^ with which it is supplied. On being torn, a number of gran- ules are seen, which seem to compose the great body of the cortical portion, and are called the corpora, or acini of Halpiglii. These acini exist in immense numbers, and are seen as very minute, round, red points, their diameter being about the tenth of a line. Their con- nection with arterial branches is compared to that of ber- ries with their stems. Some, among whom is the distin- guished Euysch, regard the acini as consisting wholly of blood-vessels, while others view them as little glandular sacs for secreting the urine, around whose walls the blood- vessels are ramified, and from which arise the commencing uriniferous or excretory ducts. According to Mr. Bowman, these acini are composed of capillary arteries coiled up in loops and closely compressed, so as to form vascular balls, which are enclosed in dilata- tions of the urinary tubes, forming capsules for each. FIG. 206 represents a section of the right Kidney, having the renal capsule on its top. 1 Supra-renal capsule. 2 Cortical portion. 3 Medullary or tubular portion. 4 Calyces. 5 Infundibula. 6 Pelvis. 7 Ureter. 640 THE KIDNEYS. Each capsule is perforated by an artery called vas inferens, which goes to form this vascular ball, and from the inte- rior of each there passes out through the capsule a small vein called vas ejferens, which, with other veins of like kind, goes to the venus plexus surrounding the convoluted urinary tubes. Two systems of vessels are here described, first the arterial capillary, composing the acini of Malpighi within the urinary capsule, and second, the venous capillary on the outside of the capsule surrounding the urinary tubes, and constituting a plexus which is compared to the portal plexus of the liver. This plexus is believed by Mr. Bowman to secrete the urea, lithic acid, and other solid portions, while he assigns to the arterial plexus or acini, the separation of the water and soluble elements of the urine. The internal or tubular portion, (Fig. 206,) called also pyramides Malpighi, consists of fine tubes collected in fasci- culi, forming cones, of which there are about fifteen. These cones are of a dense structure and pale color, with their bases at the circumference, and their apices at the central cavity of the kidney. They are separated and surrounded by the cortical substance, constituting the several conoidal fasciculi so many distinct lobes, or miniature kidneys, which are distinctly marked upon the surface of the foetal kidney. The apex of each cone is free, and forms a projec- tion into the central cavity termed papilla or mammary process. The papillae are not so numerous as the cones, as two or more of the latter converge into one of the former. The papillae are arranged into an anterior, middle, and poste- rior row ; and each one presents several foramina, through which the urine passes from the tubuli uriniferi. Each cone or pyramid consists of a collection of these tubuli, which are more numerous at the base than at the apex, in consequence of their coming together as they approach the latter. They are compared to fine hairs, and are proven to be conductors of the urine, by making a section of them and squeezing the cortical portion, when drops of urine THE KIDNEYS. 641 are seen to ooze out. They are convoluted tubes, in the cortex,, called the tubes of Ferrein, intertwining here with the venous and arterial capillaries, and ending either in loops or co3ca ; while in the pyramids or cones these tubes pursue a straight course. The papillae are surrounded by funnel-like formations of a fibre-mucous character, called infundibula. The papillae are sometimes more numerous than the infundibula, in which case two or more of the former are found to one of the latter. The infundibula come together or run into each other so as to form three compartments — one in the middle, and one at each end of the kidney, which, from their cup-like form, are termed calyces, and these calyces, by their union, expand into the oval cavity, at the inner margin of the hilus, constituting the pelvis of the kidney. The arteries of the kidneys are the renal or emulgent, and come from the aorta, at right angles. Each divides into six or more branches, which enter the fissure of the kidney, and then sub-divide into numerous minute vessels which go between the tubuli to the cortex, and form nu- merous inosculations, constituting a capillary net-work. The veins correspond to the arteries, though they are larger. They pass out of the kidney at the fissure, and go to the vena cava ascendens. The left renal vein is longer than the right, and passes in front of the aorta. The lymphatics are described as numerous, and go to the lumbar glands. The nerves come from the solar plexus, lesser splanchnic, and lumbar ganglia of the sympathetic, and are traced along with the arteries. Renal Capsules, (capsulce renales.) — These bodies are two in number, and are also called supra-renal or atra-biliary bodies. They are situated at the superior extremity of each kidney, being attached by cellular structure and blood-vessels. Their form is triangular, with the base con- cave, and resting upon the kidneys. Their color is of a yellowish brown, and their size is variable, being much larger in the foetus than in the adult. 41 642 THE KIDNEYS. The structure of these bodies consists of a thick mem- brane of cellular tissue, which surrounds and forms their proper coat, and processes which are traced within, sep- arating its several parts. In the centre a small trian- gular cavity is seen, containing, in the foetus, a viscid reddish fluid ; in the child, a yellow fluid ; in the adult, a dark brown liquid ; while, in old age, it is almost en- tirely empty. This cavity is not always found, and by some is denied to exist at all, and when present is attributed either to the enlargement of a vein, decomposition, or laceration. The arteries come from the renal, aorta, and phrenic. The veins of the right go to the vena cava ascendens ; those of the left enter the emulgent. The nerves are from the renal and solar plexus. Each capsule is divided into lobes, and these again have been divided into lobules, having granules, which are found to be connected with the veins. Function. — The use of the renal capsules is as yet un- known. In the foetus, like the thymus and thyroid bodies, they are large, and are supposed to be connected with foetal sanguification. Function of the Kidneys. — The use of these glands, it is well known, is to secrete the urine ; and the cortical por- tion of the kidney, which is exceedingly vascular, has been assigned as the especial part where the secretion occurs, while the tubular conveys the fluid down the coni- cal fasciculi to the papilla?, through which it passes into the pelvis. The uriniferous tubes are lined by mucous membrane, and are found by Henle to contain epithelial cells, which, as in other glands, are regarded as the true secreting agents. When filled, they break and discharge into the tubuli uriniferi, others being formed from the nuclei of the extinct cells. The urine is composed principally of water. It also contains urea., a substance highly charged with nitrogen, and also lithic or uric acid. In children hippuric acid is found instead of the lithic. Lactic acid, an animal extractive THE URETERS. 643 substance, and various salts, as the phosphate" and sulphate of lime, muriate of ammonia and soda, and salts of magne- sia, are also found as constituents of the urine. SECTION II. THE URETERS. The ureters, (Fig. 205,) one for each kidney, are the ex- cretory ducts, and extend from the kidney to the bladder, conveying the urine from the former into the latter. Thej are about the size of a goose quill, and of an average length, of eighteen inches. They commence in the pelvis of the kidney, and emerging at the fissure behind the vessels, take a course downward through the lumbar regions, upon the anterior surface of the psoas magnus, and behind the peritoneum, crossing the primitive iliac arteries to the pelvis, which they enter. Here they cross the internal iliacs and vasa deferentia, and proceed to the back part of the bladder, which they enter by passing very obliquely through its coats, and terminating about ten or twelve lines from the neck. In the female, the ureter is in relation with the Fallopian tubes and broad ligaments. The ureters consist of two coats, an outer or fibrous, and an inner or mucous coat. The fibrous is composed of dense cellular tissue. The mucous is pale, without valves, and traced into the bladder. These tubes are larger at their commencement and ter- mination than in the middle. They are capable of great dilatation, as seen in cases of obstructed urine, and in the passage of large calculi to the bladder, in which condition! they exhibit the greatest sensibility. SECTION III. THE BLADDER, (VESICA URINARIA.) The bladder is a musculo-membranous sac, situated mostly within the pelvis, behind the pubis, and in front of the rec- tum. It is the largest of all the reservoirs of secretion, and receives the urine from the ureters. 644 URINARY BLADDER. Its position and capacity vary according as it is full or empty, and also according to age, sex, habit and disease. When empty, in the adult, it is contracted and found below and behind the pubes, and presents a flat, triangular shape. When moderately distended, it rises above the pubis, in con- tact with the recti muscles, and in front of the peritoneum, and assumes the form of an ovoid, the larger end being be- low upon the rectum, the smaller end above ; when com- pletely full, it rises still higher, enlarging more and more, and having its larger end above and the smaller below. In the foetus it is relatively larger than in the adult. In the female it is larger than in the male, and the habit of retain- ing the urine renders it larger than when the calls of nature are promptly attended to. In disease every variety of size and the highest and lowest positions are seen. The form of the bladder has been stated to be ovoid or FIG. 207. egg-shape, but presenting differen- ces according to causes above men- tioned. Its direction or long axis is oblique from above downward and backward, and this obliquity, which varies with its distention, will correspond to a line extending from between the umbilicus and pubis to the coccyx. Its divisions are into a body or central portion, an upper or superior fundus ^ a lower or inferior fundus or base, and a cervix or neck. It is retained in its position by ligaments, which are divided into the false and the true. The false are formed by reflections of the peritoneum, and are two poste- rior and two lateral. TJie posterior extend one on either side, in a semilunar form, from the front of the rectum to the back part of the bladder, and contain the obliterated FIG. 207 represents the Urinary Bladder and its appendages, a Muscular structure of the Bladder, b b Ureters, c c Vasa deferentia. d Vesiculae setninales. /Efferent duct of vesiculae seminales. g Ductus ejaculatorius. h Prostate gland, i Membranous portion of urethra. URINARY BLADDER. 645 umbilical arteries and ureters. The two lateral ligaments extend from the iliac fossae to the sides of the bladder, and contain the vasa-deferentia of the male, and the round liga- ments of the uterus in the female. This portion of the peritoneum, it is important to observe, descends upon the front and the sides of the rectum, to about four inches from the anus, leaving consequently the lower portion of the rectum uncovered by peritoneum. From this point it is reflected forward upon the bladder, at its lower and posterior part, a short distance above the base of the prostate gland, and about the middle of the vesiculae seminales, whence it passes upward upon the back and sides of this organ to its superior fundus, and is then traced onward to the abdominal muscles, as explained elsewhere. It is just below the line of reflection, and on the inferior fundus of the bladder, that the latter organ can be entered from the rectum without injuring the peritoneum. The true ligaments are two anterior and two lateral, to which are added the two obliterated umbilical arteries, and the urachuSj making seven in all. The two anterior come from the pelvic fascia, which lines the parietes of the pelvis, and is a continuation of the fascia iliaca. They commence at the lower portion of the inner surface of the pubis, on each side of the symphysis, and proceed upward to the front of the bladder, upon which they expand, as well as upon the upper surface of the pros- tate. The two lateral ligaments are also continuations of the pelvic fascia from the levatores ani muscles upon the sides of the bladder and prostate gland. The umbilical ligaments constitute the solid fibrous cords, which in the foetus were the hypogastric arteries, and are found upon each side of the fundus of the bladder going to the umbili- cus. The urachus is attached to the superior extremity of the bladder, and goes as a small fibrous cord to the umbili- cus. In the fcetus it is seen as a tubular canal, though, ac- cording to Cruveilhier, it is always solid in both foetus and adult. Upon the external surface of the bladder, six regions 646 URINARY BLADDER. have been designated by anatomists : 1. The superior, in contact with the recti muscles, and with the small intes- tines, when the bladder is distended, and attached to which are the urachus and obliterated umbilical arteries ; 2 and 3. The lateral regions, corresponding to the sides of the pelvis ; 4. The posterior region, in relation with the rectum in the male, and the uterus in the female ; 5. The anterior re- gion behind the pubis and recti muscles, deprived of the peritoneum ; and 6. The inferior region, resting upon the vesiculae seminales and prostate, and in relation with the rectum in the male, and, in the female, contiguous to the vagina. Structure. — The bladder is composed of four coats, the peritoneal, muscular, cellular, and mucous. The peritoneal or serous coat is only partial, covering simply the posterior part and sides of the bladder, extending from the summit to within an inch of the base of the prostate, whence it is reflected upon the rectum, forming the pouch which is seen between these organs. The muscular coat is arranged into fasciculi of pale fibres running in various directions, hav- ing spaces between them through which the mucous mem- brane sometimes protrudes so as to form pouches in which calculi occasionally lodge, and are not detected. The muscular fibres are seen to run longitudinally and circularly, and some again present a reticular arrangement. The longitudinal are regarded as the most numerous and strongest. They commence about the cervix and are traced upward, expanding over the anterior surface of the bladder to its summit, and thence descending upon the posterior surface and sides, back to the neck, where, according to Wilson, they are inserted into a ring of elastic tissue, as pointed out by Sir A. Cooper surrounding the beginning of the urethra, and into the isthmus of the prostate. The anterior fibres are traced into the pubes and rami of the ischia, to which they are attached by four tendons, two on each side, a superior and inferior. This muscular coat re- ceives the name of the detrusor urince. The longitudinal fibres in the female, according to Mr. URINARY BLADDER. Harrison, are " inserted anteriorly and laterally into the cellulo-vascular and glandular tissue around the cervix, and posteriorly into a more dense tissue connecting the urethra to the vagina." The circular fibres are found to be scattered, pale, and indistinct on the upper portions of the bladder, while on the lower and about the neck they become more distinct and close, and form what is considered by some a distinct muscle, called the sphincter vesicce. There are a variety of opinions in reference to this sphincter muscle ; some, with Mr. Guthrie, asserting that there are no fibres around the neck of the bladder capable of forming a sphincter, while others, as Mr. Bell, Harrison, and Homer, distinctly de- scribe them. Sir Charles Bell represents a plane of muscular fibres, forming a semicircular band, about an inch in breadth, sur- rounding the lower half of the orifice of the urethra, and at this point especially strong, and dispersing into the substance of the bladder ; while the upper half of the orifice is surrounded by a weaker set of fibres, though continuous with the lower, thus completing the sphincter. Homer speaks of a similar muscular band on the lower semi-circumference of the neck of the bladder, the fibres of which, however, he finds not to run into the ordinary mus- cular structure of the bladder, but to go transversely and be connected with the lateral lobes of the prostate ; while the superior semi-circumference presents a broad, thin, muscular layer, which is lost in the muscular structure of the bladder. Beneath the mucous membrane of the vesical triangle, this same anatomist describes a muscular structure of the same extent and shape as the triangle itself. The anterior angle he traces to the posterior part of the caput gallina- ginis. Between the two ureters, says Mr. Harrison, the circular or transverse fibres are very distinct, and a semi- lunar band forms the base of the trigone. Muscular fibres are also traced around and upon the ureters. The third set of muscular fibres, from their honey-comb 648 URINARY BLADDER. appearance and the various directions they run, are called the reticular. Some of these fasciculi are found to he quite large, and from their projections and resemblance to the columnas carneas, have heen called the columnar bladder- This arrangement produces pouches or depressions for the lodgment of calculi. The cellular or fibrous coat is between the muscular and the mucous, and consists of fibres very compact, dense, strong, elastic, extensible, difficult to tear, forming a strong bond of union between the muscular and mucous coats, and impervious to water. The fourth coat of the bladder is the inner or mucous, called also the villous coat. Its color is rather pale, or of a reddish white, and, in the contracted state, presents many folds or wrinkles, which are effaced when distended. It abounds with small mucous follicles, and is smoother than the same membrane in the stomach. Several points are noticed on the inner surface of this coat. First, is a small triangular space, below and behind the neck of the bladder, known as the vesical triangle, (tri- gone vesical.) This space forms an equilateral triangle, about an inch in length, included between the orifice of the urethra and those of the ureters. The openings for the ureters form the posterior angles, while that of the urethra forms the anterior. Mr. Bell traces a muscular bundle of fibres, forming the lateral margins of the triangle, and proceeding from the ureters to the mouth of the urethra, designed he thinks to open the ureters and allow the free entrance of the urine. This triangular space is smooth, destitute of the wrinkles common to other parts of the bladder, and is very vascular and sensitive. By the aid of the lens numerous villi are detected. At the mouth of the urethra, or anterior angle of the trigone, an eminence is observed, called the uvula vesicce. This is situated about opposite the third lobe of the pros- tate, and is formed by a projection of the mucous mem- brane, which occasionally becomes an obstacle to the intro- duction of the catheter. MALE ORGANS OF GENERATION. 649 The arteries of the bladder vary in their origin, number, and size. They come from the internal iliac, pudic, and obturator. The veins form around the cervix a plexus, which dis- charges into the internal iliac vein or some of its branches. The nerves come from the hypogastric plexus, consisting both of ganglionic and spinal filaments, which explains the fact of the bladder being both a voluntary and in- voluntary organ. Function. — The use of the bladder is essentially that of a reservoir for the urine ; and by its muscular apparatus it is the chief agent of expelling the urine, as in paralysis of the bladder no action of the abdominal muscles can effect the expulsion. CHAPTER VI. THE ORGANS OF THE TRUNK. FIFTH DIVISION. ORGANS OF THE PELVIS. THIS division comprises the organs of the pelvis, including the male and. female organs of generation. SECTION I. THE MALE ORGANS OF GENERATION. These organs comprise the testes, and their appendages, the vasa deferentia, the vesiculce seminales, the prostate gland, and the penis. The testes are two oval glands, suspended rather obliquely and having the sides compressed. The right is higher than the left. Each is surrounded by several coats, the scrotum, tunica vaginalis, tunica albuginea, and tunica vasculosa. The scrotum is a double membrane. The outer consists of the common integument, and is distinguished by being very thin, of a dark color, and so transparent that the subcu- 650 THE TESTES. taneous veins and follicles are seen through it. Hairs, run- ning obliquely, thinly cover it, and it is usually wrinkled. FIG. 208. This coat is common to both testes, and is divided into two lateral portions by a me- dian line common to the perineum and under surface of the penis, called the raplie. The next coat, or proper coat of the scro- tum, is the dartos. The dartos is a peculiar membrane, be- ing regarded as a structure between the cellular and muscular, and consisting of a contractile fibrous tissue. It is attached to the rami of the pubes and ischium, and along the mesial line, where it is found most dense ; it is reflected upward between the testes, constituting the sep- tum scroti. It presents a reddish appearance, from the quantity of blood-vessels present ; is always destitute of fat, and has its fibres running in every direction, though but loosely connected together. Its powers of contraction are well marked, as seen in the corrugation of the skin from the application of cold, and hence by some it is considered muscular. The dartos, by some anatomists, is regarded as an expan- sion of the gubernaculum testis; but as it is found in the integument of the scrotum before the descent of the testes, it is justly considered by others as entirely independent of this structure. Beneath the dartos are the fibres of the cremaster muscle, which gives but a partial covering to the testicle, and receives the name of tunica erytliroides. Next in order is a condensed cellular membrane, which surrounds each testicle and its chord, connecting the cre- master and dartos with the tunica vaginalis, and called the tunica vaginalis communis. The tunica vaginalis is a serous membrane, derived from FIG. 208 represents a transverse section of the Testicle, a Cavity of the tunica vaginalis testis. 6 Tunica albuginea. c Corpus Highmorianum. d Tu- nica vasculosa. e One of the lobules with its seminal tubes. / Section of epididymus. THE TESTES. 651 the peritoneum, during the descent of the testes from the ab- domen into the scrotum. After the descent of the testes into the scrotum, the canal for its passage hecomes closed, and this, like all serous membranes, presents the form of a shut sac. One portion of it lines the inner surface of the dartos, and is called the parietal ; the other is reflected upon the forepart and sides of the testicle, and is the visceral or tunica vaginalis testis. Between the two portions is the smooth surface and cavity in which the secretion occurs. This membrane is loosely attached to the scrotum and epi- didymis, but firmly to the testis, or rather to the next membrane, the tunica albuginea. The tunica albuginea forms the proper coat of the testis, is in direct contact with the gland, consists of a dense fibrous structure, of a bluish white color, and serves to preserve the organ in its proper shape. From its union with the tunica vaginalis, it is called a fibro-serous mem- brane, such as the pericardium and dura mater. After investing the testis, it is inflected at the posterior part, into the interior of the gland, by a vertical partition con- eisting of two laminse, called the mediastinum testis, or corpus Higlimorianum, between which are found the vessels, nerves, and ducts. Fibrous cords radiate, in great num- bers, from this mediastinum to the inner surface of the tunic, and are called trabeculce septulce. The tunica vasculosa, so named by Sir Astley Cooper, lines the interior of the albuginea, and is regarded as the nutrient membrane of the testis, bearing the same relation to the latter, that the pia-mater does to the brain. It is a very delicate membrane, consisting of a cellular web, con- taining the minute ramifications of the spermatic vessels, dipping into the substance of the gland, and sending pro- cesses between the several lobules. On dividing the tunica albuginea, the proper substance of the gland is seen presenting a soft, grayish, or yellowish appearance, consisting of numerous delicate threads, loosely connected together, and which may be drawn out, for two or more feet, without breaking. These are the tubuli semini- 652 THE TESTES. Fie. 209. feri, and are in coils or convolutions. Being collected in bundles or fasciculi, they are termed lobules, of which lat- ter there are estimated between three and four hundred, having a length, according to Dr. Monroe, of about 5208 feet. The diameter of each tube is made to measure from the 1-200 to the 1-150 part of an inch, and the length of each about 1*7 feet. Their commencement is either in loops of anastomosis or ccecal terminations, which communicate, though the tubes of one lobule are said not to inosculate directly with those of another. The lobules present a conical form, having their bases towards the surface, and their apices towards the mediasti- num testis, consisting of one or many convoluted tubuli seminiferi, and are enclosed and separated by processes from the tunica albuginea and vasculosa. The tubuli seminiferi of the lobules coalesce in about twenty or thirty straight tubes, called vasa recta, which, entering the mediastinum and interlacing here with each other and with the vessels and nerves of the gland, receive the name of rete testis. The rete testis is situated at the poste- rior part of the gland, and, at its upper part, passes through the tunica albugi- nea, by from ten to thirty tubes, called vasa efferentia, each of which, becoming convoluted, receives the name of conus vasculosus. From the bases of these coni vasculosi, larger tubes are formed, constituting the epididymis. The epididymis is situated upon the outside of the tunica albuginea, upon the back of the testis, being connected to the latter by the reflected tunica vagin- alis, and taking a vertical direction. It is formed of the FIG. 209 represents the minute structure of the Testicle. 1 1 Tunica albu- ginea. 2 2 Corpus Highmorianum. 33 Tubuli seminiferi. 44 Vasa recta. 5 Rete testis. 6 Vasa-efFerentia. 7 Coni-vasculosi, or globus major. 8 Epi- didymis. 9 Globus minor. 10 Vas-deferens. 11 Vasculum aberrans. THE TESTES. 653 convoluted coni vasculosi, presenting an arched form, the larger end of which is above, and called the globus major; the lower end is the globus minor, while the intermediate portion constitutes the body. The epididymis can be unraveled into a single conro- luted tube, having an estimated measure of twenty-one feet, and receiving at intervals of about three inches the coni vasculosi. At the lower part of the epididymis this tube is less convoluted, and ends in the vas defer ens, the excretory duct of the testicle. The vas deferens is a large tube of cartilaginous density, proceeding from the globus minor to the vesiculae semi- nales, and designed to conduct the semen into the latter from the testis. It ascends parallel with the epididymis, and above the head of the latter becomes one of the con- stituents of the spermatic cord, along the back part of which it ascends to the internal abdominal ring ; here it leaves the vessels of the cord, and dipping into the pelvis, is enclosed in the lateral fold of the peritoneum, along which it proceeds to the side and inferior fundus of the bladder, where it converges towards its fellow on the in- side of the vesictilae seminales, at the angle of their junc- tion, and at the base of the prostate each vas deferens joins the corresponding duct of the vesiculas seminalis, forming the ductus ejaculatorius , which passes through the prostate, and opens into the urethra near the neck of the bladder on the side of the caput gallinaginis. The vas deferens consists of two coats, an external, which is thick, hard, and firm, and regarded as fibrous ; the internal is thin, pale, and mucous. Just before the commencement of the vas deferens, a second tube is seen to leave the epididymis and run for a short distance parallel with the vas deferens, which it either joins or ends in a cul-de-sac. It is called vasculum aberrans (or blind duct) of Holler. The spermatic cord consists of the vas deferens just de- scribed, the spermatic artery and veins, nerves, and lymph- atics covered by cellular membrane, and the cremaster 654 THE TESTES. muscle. It extends from the epididymis to the internal abdominal ring, and is covered by the remains of the peri- toneum, which accompanied the descent of the testis, called the tunica-vaginalis of the cord. The spermatic artery comes from the abdominal aorta, Bometimes from the renal artery, proceeds along the psoas muscle to the internal abdominal ring ; here it joins the spermatic cord, and descends along with it to the back part of the testicle, where it enters the rete testis by divid- ing into several branches, which again subdivide very minutely around the tubuli seminiferi. A branch goes to the vas deferens from the superior vesical called deferential, and one to the creinaster muscle from the epigastric, the cremasteric artery. The veins, on leaving the rete testis, become very tortu- ous, twine round the arteries and form a plexus called the corpus pampiniforme, constituting the principal bulk of the cord. The right spermatic vein ends in the inferior cava near the renal. The left ends in the left renal vein. The nerves come from the spermatic plexus. Branches also from the lumbar plexus go to the cremaster. The lymphatics go to the lumbar glands. The testes are not seen first in the scrotum, but are situ- ated in the abdominal cavity, immediately beneath the kidneys and behind the peritoneum. They are represented as being about two lines long in the middle of the third month of uterine life. About the fifth or sixth month they have descended as low as the inferior portion of the psoas muscles. In the seventh month they are seen in the iliac fossa ; in the eighth in the abdominal canal ; and a few weeks before birth they are found to reach the scrotum. The gubernaculum testis is a cord composed of cellular and ligamentous fibres, extending from the inferior portion of the testicle to the scrotum, and is regarded as the agent by the contractile power of which the testis descends or is drawn into the scrotum. function of the Testes. — The office of these glands has been already stated to be to secrete the semen, a fluid VESICUL.E SEMINALES. 655 which, according to the microscope, contains numerous little filamentary bodies termed spermatozoa or seminal animalcules , and granules, which constitute the elements of the reproductive cells, by which the germs for the con- tinuance of the human species are provided. The Vesiculw Seminales} (Fig. 207.) These bodies are two in number, and situated on the under surface of the bladder behind and above the prostate, and in front of the rectum. They diverge behind, and converge in front, where they are separated only by the vasa deferentia. They are attached to the bladder by cellular tissue, and are sur- rounded by a venous plexus. The form of each is oval, having a length of about two inches, and a breadth of half an inch. They present the appearance of cells, but are found to consist of one continuous convoluted tube, the sev- eral coils communicating, and being connected by cellular tissue. Each vesicula has two coats, an external of fibro- cellular substance, and an internal or mucous. Each vesicle has an excretory duct about a line and a half long, which, uniting in the substance of the prostate with the vas deferens, forms a common duct, the ductus ejaculatorius , which is about three quarters of an inch long, passing for- ward through the prostate, and opening into the urethra on the anterior edge of the caput gallinaginis. These bodies communicate freely with the vas deferens, and are considered as reservoirs for the semen, but they are found also to contain a fluid of their own secretion, consisting of mucus of a yellowish brown color and viscid consistence. Prostate Gland, (Fig. 207.) — This body is situated upon the neck of the bladder, and about an inch on the urethra. In shape and size it resembles a horse-chestnut. It is behind the triangular ligament, and in front of the rectum, to which it is attached by cellular structure. Its base looks backward, and its apex forward towards the urethra. It is about an inch in length, and half an inch in thickness. It is fixed by the anterior liga- ments of the bladder to the symphysis of the pubis, and by the posterior layer of the triangular ligament, consti- 656 THE PENIS. tuting a strong fascia, which invests the sides and infe- rior surface of this gland, thus forming for it a capsule. Its density is firm and resisting. Its color is of a grayish hue. The posterior surface is flat and notched, which divides it into two lateral lohes, and on raising the vesicu- las seminales, a transverse process is ohserved connecting the lateral lobes, called hy Sir Everard Home the third or middle lobe of the prostate. The sides of the prostate are round, smooth, and covered by the levatores ani mus- cles, veins, and a strong fascia. The structure of this gland consists of mucous follicles, which discharge by ten or more excretory ducts into the urethra on either side of the caput gallinaginis, and these follicles are surrounded by a condensed fibrous or cellular tissue. The fluid of this gland is white or brownish, and viscid. THE PENIS. The penis is connected to the symphysis pubis, and in front of it. It is divided into a root, body, and extremity. The root is attached by two crura to the rami of the is- chium and pubis. The body forms the intermediate or cen- tral portion, while the extremity consists of the glans penis. Structure. — The penis consists of integument, cellular tissue, the corpora cavernosa, corpus spongiosum, and ure- thra. The integument is delicate, thin, loose, and free from fat. It projects beyond the extremity of the glans, so as to form a loose sheath termed the prepuce. It is then re- flected back to the root of the glans, thence over the glans itself, where it is very delicate, and is traced to the open- ing of the urethra continuous with the lining membrane of this canal. The prepuce is connected to the glans by a longitudinal fold or process called frenum preputii. Its in- ner layer is mucous and is connected to the outer by loose cellular tissue, which readily allows the infiltration of se- rum. Around the corona of the glans, and beneath the skin, numerous sebaceous glands are seen, called glandulce odoriferce or glands of Tyson. THE PENIS. 65T The cellular coat is occasionally found much condensed, and lost in the fascia of the thighs. It is described as being reflected from the linea alba, upon FIG. 210. the penis, as far as its extremity, being particularly strong where the penis is connected with the pubis, and constituting its sus~[ pensory ligament. This ligament1 consists of dense, fibrous tissue, in which elastic fibres have been de- tected, and it is supposed some mus- cular fibres have also been seen. The corpora cavernosa form the largest portion of the penis, and consist of two semi-cylindrical bodies of considerable length, placed side by side, and having a partition between them, though rather imperfect, termed septum pectiniforme. The corpora caver- nosa arise by two conical crura from the rami of the ischia and pubis, beginning in front of the tuber ischii, and proceeding to the lower part of the symphysis, where they unite to form the body ; upon the extremity of which is situated the glans penis. The two corpora, rep- resenting two cylinders placed side by side, present be- FIG. 210 represents the Penis and Bladder laid open. 1 1 Bladder. 2 2 Ureters. 3 3 Vesical orifices. 4 Uvula vesicae. 5 Superior (Vndus of blad- der. 6 Bas-fond of bladder. 7 Centre of vesicle triangle 8 Caput gallina- ginis or verumontanum. 9 Opening of the ductus ejaculatorius 10 Depressiom near the caput. 11 Ducts from prostate gland. 12 13 Lateral lobes of th« prostate. 14 Urethra, its prostatic portion. 15 Membranous portion. 10 Cowper's glands. 17 Point of entrance of their excretory ducts. 18 Bulb of urethra laid open 19 Section of corpora cavernosa. 20 Glans penis divided. 21 Prepuce taken off. 22 Internal portion of urethra laid open. 23 Exterior portion of corpora cavernosa. 2425 Accelerator-urinae muscle. 2627ErecU*. penis. 42 658 THE PENIS. tween them two grooves, the one superior, occupied "by the dorsal vessels and nerves ; the other, inferior, contain- ing the urethra. Each corpus consists of a white, very strong, fibrous, and elastic membrane, consisting mostly of longitudinal fasciculi closely interlacing each other, though an internal layer of circular fibres, as continuous with the septum, is also seen. From the inferior groove, a number of radiating fibrous bands are seen crossing the cavities of the corpora to be inserted in the inner walls of this fibrous tunic ; these cords are called trabeculce, and are believed to strengthen the organ as well as to limit its distension. The interior of each corpus is occupied by a soft, cellulo-vascu- lar, or erectile tissue, presenting a spongy appearance, or a multitude of cells, all of which communicate freely with each other and with the veins, and consist, says Dr. Morton, of an intertexture of veins closely woven together, so as to present the appearance of cells, which veins or venous plex- uses are supported and separated by the trabeculse. The corpus spongiosum surrounds the urethra, and ex- extends from between the crura about an inch behind their junction to the extremity of the penis. Its poste- rior extremity is called the bulb — its anterior the glans penis. The base of the glans presents a projection or shoulder, termed the corona glandis, and behind this is noticed a contraction called the neck. The structure of the corpus spongiosum resembles the cavernosum, except that its external aponeurotic coat is much thinner, and its interior spongy erectile tissue much finer and more delicate. There is no direct communication between the corpora cavernosa and spongiosum, though a fine injection from the pudic artery will occasionally suc- ceed in injecting both at the same time. The urethra (Fig. 210) is a membranous canal situated along the inferior groove of the corpora cavernosa, and ex- tending from the neck of the bladder to the extremity of the penis. The course of this canal from the neck of the "bladder is first forward and downward, covered by the prostate gland, and called the prostatic portion. It then THE PENIS. 659 proceeds to the symphysis pubis, beneath which it makei a slight curve, having the concavity upward. This portion is called the membranous, while the balance, commencing at the bulb and going to the extremity of the glans, receives the name of the spongy portion. The length of the urethra varies according to the erection of the penis, averaging from seven to nine inches. To the prostatic portion is given about an inch and a half, and to the membranous about an inch. The urethra is composed of two coats, an outer fibrous and elastic, and varying in strength and density at different points, being stronger in the prostatic and membranous portions than in the spongy; and the inner or mucous coat which is smooth and thin, and continuous with the mucous coat of the bladder poste- tiorly, and the integument of the glans anteriorly, also with the lining membrane of the excretory ducts of Cow- per's glands, the prostate, the ejaculatory ducts, and the several lacunae. The prostatic portion is considered the widest part of the canal ; on its lower surface the mucous coat presents a lon- gitudinal fold along the mesial line, called caput gallinagi- nis or verumontanum. On each side of the caput gallinaginis a fossa is seen, called prostatic sinus, in which the ducts of the prostate open. At the anterior extremity of the caput the common ejaculatory ducts are found to terminate, and between the latter, an opening looking backward into a small dilated sac, is noticed, called sinus pocularis. The caput gallinaginis is regarded in the light of a valve to prevent the escape of urine in the contracted state of the urethra ; but during the action of the detrusor urinse, the caput is drawn down and the elastic ring expanded so as to permit the escape of the urine. The membranous portion, is the narrowest part of the canal, and is surrounded by an elastic and erectile reddish tissue, and the deep layer of the triangular ligament,with the compressores urethrae muscles It lies between the prostate and bulb. In the latter the urethra again enlarges, and then again in the spongy por- tion, which is the longest of the three, becomes smaller till 660 THE PENIS. it approaches the glans, where it becomes so large as to receive the name of fossa navicularis. The mucous coat is very sensitive, and so numerous and superficial are its veins, as to bleed freely, often, on introducing the catheter. The urethra abounds with mucous lacunae, especially upon its upper wall, which discharge their secretions into this canal ; their orifices present forward, and are believed sometimes to interrupt the course of the catheter. One of these, about an inch and a half, from the meatus is named the lacuna magna. Cowper's Glands. — These are two bodies about the size of peas situated behind the bulb, and covered by the accelera- tores urinae muscles. They are of a yellowish color, hard, and sometimes not found. They each discharge into the urethra in front of the bulb by an excretory duct which runs forward for about an inch. The arteries of the* penis come from the terminal branches of the internal pudic. The internal pudic arises from the internal iliac, forming one of its terminating branches ; sometimes it comes from the ischiatic, along with which it leaves the pelvis below the pyriform muscle, returns again between the sacro-sciatic ligaments, and then ascends along the inner side of the tuber and ramus of the ischium and pubis, to a short distance below the symphysis, wheie it ends in two branches. In this course, besides supplying branches to the bladder, rectum, vesiculse seminales, prostate, and to the vagina in the female, it sends off opposite the ramua of the ischium the artery of the bulb, which passes between the triangular ligament, and is distributed through the corpus spongiosum as far as the glans. The terminating branches of the internal pudic are the arteria dorsalis penis and arteria corporis cavernosi. The former goes between the crura upon the dorsum of the penis as far as the prepuce, which it supplies, also forming a circle around the corona glandis, and anastomosing with branches in the glans of the corpus spongiosum. The artery of the corpus cavernosum enters the crus, and runs along the septum, giving oif branches as it proceeds. Muller speaks of arteries which he calls arterice helecince, FEMALE ORGANS OF GENERATION. 661 coming off from the pudic, and going to the venous cells in tufts. The existence of these, however, is denied b7 other anatomists. The veins are numerous and large, and supplied with valves. They are divided into the superficial and deep. The former begin in the prepuce, form the two dorsal veins of the penis, which go to the root of the penis, receiving branches in their course, and then pass beneath the arch of the pubis to join the plexuses of the bladder and pros- tate gland. The deep veins accompany the pudic artery and its branches, and join the internal iliac. The nerves of the penis come from the internal pudic, which has its origin from the lower part of the sacral plexus. The internal pudic nerve takes a similar course with the internal pudic artery, along the inner surface of the tuber and ramus of the ischium, covered by the obtu- rator fascia, and towards the pubis it divides into a supe- rior and inferior branch. The superior nerve accompanies the arteria dorsalis to the glans of the penis, which it sup- plies. It sends off at the root of the penis a branch which enters the corpus cavernosum, also a cutaneous branch, supplying the integument and prepuce. The dorsal nerve in the glands of the penis is observed to expand, and as- sume a reddish, ganglionic appearance, sending off delicate filaments, which are traced to the very sensitive membrane covering the glans. The inferior branch of the pudic supplies the bulb and corpus spongiosum, the scrotum, muscles and integuments of the perineum, and the anus. Branches of the sympa- thetic are also traced to the penis. SECTION II. THE FEMALE ORGANS OF GENERATION. These comprise the external and the internal organs of generation. The external organs of generation include the Mons veneris, Labia majora, Labia minora, Clitoris, Meatus urinarius, Orifice of the vagina. 662 THE VULVA. The term vulva is applied, by some anatomists, to all these parts; while others restrict this term simply to the fissure or urino-sexual opening between the labia major a. The mons veneris is the prominence situated on the front and upper part of the pubis. It is composed chiefly of cel- lular tissue, abounding with adipose matter, and, in the adult, is covered with hair. The labia majora, or externa, are two longitudinal folds of integument, situated upon either side, and extending from the rnons veneris in front, to their common junction behind, in a crescentic edge or commissure called the four- chette. Between this latter and the vagina a depression is observed, termed the fossa navicularis. Between the fourchette and the anus, a distance of about an inch, is the perineum. The labia, like the mons veneris, consist of loose cellular tissue and fatty matter, and consti- tute the anterior boundary of the sexual organs. The external surface is covered with hair, the internal is a mucous membrane, covered with a smooth, delicate epi- thelium, and containing numerous sebaceous follicles. The use of these labia seems to be, to favor the expulsion of the child, as during parturition they are found completely unfolded. The labia minora, or interna, called also nymplice, are situated within the greater labia, and consist of two smaller folds of mucous membrane, which descend and are lost upon each side of the vaginal orifice. They are also cov- ered by a fine epithelium, have many sebaceous follicles, and enclose an erectile tissue. They are broad before, narrow behind, proportionally more developed than the greater labia in the infant, and sometimes found very much enlarged and elongated from hypertrophy. In par- turition they are also unfolded, and disappear. The clitoris is situated directly below the symphysis pubis, and is compared to the male penis. It presents a small red prominence, constituting a body, which is formed by the union of the crura, arising from the rarni of the pubis and THE URETHRA. ischium, and joining opposite the symphysis ; to which they are connected by a suspensory ligament. The body is from half an inch to an inch long, rather curved, looks down- ward from between the anterior commissure of the labia, and from having some resemblance in its extremity to the glans penis, is called the glans ditoridis. The clitoris is covered by a fold of the mucous membrane, derived from the upper part of the nympha?, and called prceputium dito- ridis. In structure the clitoris resembles the corpora caver- nosa penis, in having an exterior fibrous sheath, and an interior spongy, erectile tissue. It is also supplied in pretty much the same manner with blood-vessels and nerves, as the penis, but, unlike the latter, is imperforate, and not concerned in conducting the urine from the bladder. There is also an erector muscle to this body, like the erector penis, which will be described under the head of perineum. The clitoris, like the nymplise, is large in the infant, and has been seen elongated to the extent of one or two inches. The meatus urinarius is situated about an inch below the clitoris, immediately above the vagina, and is always readily detected by the presence of a small tubercle surrounding it. This orifice is found in the small triangular depression be- tween the clitoris and vagina, called vestibulum, and is the external opening of the urethra. The female urethra is about an inch and a half long, pro- ceeds backward and upward upon the upper surface of the vagina, with which it is very strongly connected, passes beneath the symphysis pubis, to which it is also attached by the anterior ligaments of the bladder, and after forming a slight curve, goes to terminate in the neck. This canal is larger and more dilatable than the male urethra. It consists of a mucous coat, continuous with that of the blad- der, of a red color, having longitudinal folds, with numer- ous mucous follicles, and of an external coat of condensed cellular tissue, which is also elastic, erectile, and muscular in its nature. The orifice of the vagina is directly below the meatus uri- narius, and is bounded laterally by the nymphse. Its form 664 THE VAGINA. is oval, and presents a projecting, and somewhat thickened and corrugated margin. It is generally closed by a fold of the mucous membrane, called hymen. This hymen forms a septum which presents a variety of forms ; sometimes it is circular, with an opening in the centre and a fringed edge, sometimes semilunar witb an opening in front, sometimes a transverse septum with two openings, then again a com- plete septum without any opening, in which case the men- strual secretion is confined, a condition whicb is attended with some danger ; and then again the hymen may be entirely wanting. When ruptured, its margin presents from two to six or more fringe-like processes or tubercles, termed carunculce myrti-formes . The internal organs of generation include the vagina, the uterus, the ovaries, and the Fallopian tubes. The vagina is a membranous canal leading from the FIG. 211. Yulvato the uterus, and is situated between the bladder and rectum. Its direction is upward and backward. It is about six or seven inches in length, and in the axis of the outlet of the lower pelvis, forming an angle with the uterus, and being somewhat concave in front and convex behind. Its anterior and posterior surfaces are flattened and in contact, the anterior being the shorter of the two. Its anterior extremity is smaller, and presents its greatest diameter Fie. 211 represents the female internal Organs of Generation, a Upper portion of vagina. 6 Os-uteri. c Cervix uteri, d Body of the uterus, e Fun- dus. /Broad ligament, g i Fallopian tube, h Round ligament, j Fimbriated extremity of Fallopian tube, fc Its connection with the ovary. / Ovary, m Round ligament. THE VAGINA. 665 vertically ; while the posterior or uterine is the larger, and has its greatest diameter transversely. The vagina surrounds and is prolonged for a short dis- tance upon the uterus, presenting a circular depression. It is connected in front to the bladder very closely, by means of a reddish structure resembling the dartos ; and has, at this point, an inseparable attachment to the urethra. Be- hind, the peritoneum is attached to its upper third, while the lower is connected to the rectum by a loose dartoid tis- sue ; upon its sides are seen the levatores ani, the pelvic fascia, and the broad folds of the peritoneum. The structure of the vagina consists of three membranes, a mucous, erectile, and fibrous. The mucous, or internal coat, is continuous with that upon the labia, and presents about the vulva a vermillion tinge, while, at its uterine portion, it is seen of a marbled or grayish hue. It presents numerous transverse rugae, which are not unfolded, but form a roughened surface most distinct on the upper part. Along the median line of each surface a prominent ridge is observed, called the columns of the vagina. This coat abounds with mucous follicles and papillae, and is covered by a distinct squamous epithelium. The erectile or middle coat, called also plexus retiformis from the abundance of its veins, consists of a spongy tissue, and is compared to the corpus spongiosum urethrse. It is enclosed between two fibrous laminae, and is found in the greatest quantity about the anterior extremity of the vagina. The sphincter vagince muscle covers this middle coat. The external coat is fibrous, consisting of condensed cel- lular structure, is very elastic, and resembles the dartos. On each side, near the middle of the orifice of the vagina, and beneath the sphincter muscle, is seen a mucous gland about the size of a pea, which is compared to Cow- per's glands. Their excretory ducts open in front of the carunculae myrtiformes. The uterus is situated between the bladder and the rec- 666 THE UTERUS. turn, in the cavity of the pelvis. Its form is triangular or pyriform. Its size varies ; the average dimensions being about three inches in length, two in breadth at the supe- rior portion, and one inch in thickness, in the uniinpregna- ted state. Its divisions are into ihefundus, body, and neck. Thefundus is the superior portion between the Fallopian tubes ; the neck is the inferior, cylindrical, and constricted part ; while the intermediate portion constitutes the body. The direction of the uterus is downward and backward, corresponding to the axis of the superior strait, and forms an angle with the vagina which runs forward and down- ward, in the axis of the lower strait. The uterus has its anterior surface flattened and covered in its upper half by peritoneum, which is reflected upon the bladder, forming the anterior or vesico-uterine liga- ment. The posterior surface is convex, being entirely covered by peritoneum, which is reflected upon the rectum, forming the posterior or recto-uterine ligaments. The sides have the broad, round, ovarian ligaments, and the Fallo- pian tubes attached to them. The broad ligaments are two folds of the peritoneum, ex- tending from the uterus to the sides of the pelvis, and thus dividing the cavity of the latter by a transverse septum, separating the bladder from the rectum. The round liga- ments are situated in front and below the Fallopian tubes, in the anterior fold of the broad ligaments. They ascend to the internal ring, through which they pass, being sur- rounded at this point by a sheath from the peritoneum, called the canal of Nuck ; thence they descend the inguinal canal, and pass out the external ring to be lost in the mons veneris. These ligaments consist of condensed cellular or fibrous tissue, with numerous blood-vessels and nerves from the spermatic plexus ; muscular fibres have also been seen entering into their composition. Their function is to retain the uterus in its natural position. The ovarian ligaments, about two inches in length, extend from the superior and lateral angles of the uterus, below and behind the Fallopian tubes, within the posterior fold THE UTERUS. 66? of the broad ligaments, to the ovaries. They are regarded as fibro-muscular, and serve to fix the ovaries. The supe- rior extremity or fundus of the uterus is convex, and presents upward and forward behind the bladder, and, in the undis- tended state, below the brim of the pelvis. The inferior ex- tremity or cervix looks downward and backward, and is surrounded by the vagina, into which it projects. It pre- sents the os-tincce or uteri, which in the virgin is a circu- lar opening, with smooth borders, but in the female who has borne children, it is more projecting, larger, slightly wrinkled, and more transverse, being divided into an an- terior and posterior lip. The anterior or superior is thicker than the posterior or inferior, which is longer. The uterus, when opened, presents a triangular cavity, the base of the triangle being above, and having at each angle the small funnel-shaped orifice of the Fallopian tube. The sides of the triangle are curvilinear, and the inferior angle forms the os-uteri, which is seen in the vagina. This cavity has been found deficient. The cavity of the neck is cylindrical and flattened, arid smaller at either end than in the middle. Structure. — The uterus is composed of an external or se- rous coat, an internal or mucous, and an intermediate tis- sue, called the proper fibrous or fibro-muscular, with blood- vessels and nerves. The serous coat and its ligaments have been already described. The mucous coat is a thin, smooth, delicate membrane, lining the internal cavity, of a pale color, be- coming brighter during menstruation, and covered by an epithelium, columnar and ciliated. In the neck it pre- sents, along the middle, longitudinal lines or columns, from which transverse rugfe or folds are observed to pass, and which, from their arborescent appearance, receive the name of arbor-vita;. Between these folds are found many mucous follicles, whose mouths, from irritation or any other cause, becoming obliterated, present the form of small spherical sacs, from the accumulation of their secre- tions, which Naboth mistook for eggs or rudiments of the 668 THE UTERUS. foetus, and were called ovula Nabothi. This coat is more vascular in the body than in the neck, and is so delicate and difficult of demonstration that some have even denied its existence. The middle coat or proper tissue is composed of strong, grajish fibres, closely interwoven, and, in the unini- pregnated state, presenting the density of cartilage under the knife. The true character of these fibres is yet unset- tled, some contending that they are muscular, others that they are fibrous, while others regard them as fibrous in the unimpregnated, and muscular in the pregnant or- gan. This latter opinion seems to correspond with the changes observed in the uterus before and after pregnancy. In the former or quiescent state, the uterus, as stated, is condensed and compacted in its fibres — hard, without con- tractility, and presenting very little the appearance of muscular tissue ; while during gestation the blood-vessels become greatly enlarged, the sensibility much exalted, and the fibres softened, loose, immensely contractile, as proven by the state of labor, and exhibiting, in an eminent degree, all the characteristics of muscles of organic life. In this state of gestation the fibres are seen to be ar- ranged into two layers, a superficial and deep — the former longitudinal upon the anterior and posterior surface of the body, oblique upon the sides and fundus, and continued upon the Fallopian tubes, round, and ovarian ligaments. The deep layer is seen to consist of two series of conical fibres, the base being in the body of the uterus, and the apex at the Fallopian tubes. Around the neck the fibres are circular, intersecting each other at different angles. Of the arteries of the uterus, two, the uterine, come from the internal iliac, and two, the spermatic, from the aorta. The uterine veins are very large, and during pregnancy are called sinuses ; they discharge into the internal iliac and renal veins, and the vena cava. The nerves, during pregnancy, are also large and well developed; they come from the hypogastric and renal plexuses, with some of the anterior branches of the sacral nerves. The lymphatics of the uterus, in gestation, are, like the veins, very large. THE OVARIES. 669 Function. — The uterus receives and retains the ovum during the whole period of gestation, from a short time after conception, to birth ; and is also the prime agent in the expulsion of the child. THE OVARIES. The ovaries (testes muliebres, Fig. 211,) are two small, flattened, oval bodies, one on each side of the pelvis, situated in the posterior fold of the broad ligament, and connected to the uterus by means of the broad and round ligaments. These bodies are of a pale color, about an inch in length, and about an inch and a half distant from the uterus. Both the situation and size, however, depend- upon age and pregnancy. In the foetus, like the testes, they occupy the lumbar regions, whence they gradually descend into the pelvis. During pregnancy they ascend into the abdomen along with the uterus, and after partu- rition, for a short time, they are found in the iliac fossa. They are proportionally larger in the foetus than in the. adult, are found to lessen in size after birth, to enlarge again at puberty, and then to diminish and become wasted in old age. Structure. — Each ovary is composed of an outer coat, which is serous and derived from the peritoneum — a middle, which resembles the tunica albuginea of the testes, and is a white, strong, fibrous capsule, sending prolongations into the interior of the gland, which divide it into irregu- lar partitions, like the interlacing of areolar tissue. Lining this fibrous coat is seen a vascular one, which also goes into the interior, and assists in forming the areolar or cel- lular tissue. This latter tissue is the stroma or spongy bed of authors, in which are deposited a number of small vesicles called the Graafan vesicles. Their average number is from ten to fifteen in the mature state, though the microscope re- veals numerous others not yet arrived at maturity. Each of the Graafian vesicles is represented as a small, trans- parent cyst, varying in size from a pin's head to that of a 670 THE OVARIES. small pea, having thin, transparent walls, and enclosing a fluid, either colorless or yellow. This fluid is said to be albuminous, and to contain microscopic granules, and, at the least, one ovum. The walls of the vesicle are observed to consist of two coats, an external or vascular, regarded as simply the thickening of the surrounding stroma, and an internal coat, transparent, structureless, and lined with an epithelium, constituting the true ovisac. The ovum,) according to the microscope, is about the 1-120 of an inch in diameter, and is siirrounded by a transparent membrane, containing the yolk, which seems to consist of granules or cells, and fat globules. In the yolk is also seen the germinal vesicle of PurJcinje. This vesicle contains a transparent fluid, and has also within it the germinal spot of Wagner, called macula germinativa, about the 1-200 or 1-300 of a line in diameter. The granules of the ovum are arranged into a membraniform structure called membrana granulosa. The corpus luteum is a yellowish or brownish spongy tissue, containing a small cavity, and is regarded as the remains of the ruptured Graafiari vesicle after the escape of the ovum at impregnation. This cavity presents a puckered membrane lining it, the remains of the ovisac. In the recent state, the opening into this sac is distinct, but after parturition it becomes closed, leaving nothing but a cicatrix to indicate its position. But in time the cicatrix is known to be effaced, and even in a girl of only five years a corpus luteum has been seen, so that the absence of the cicatrices cannot be regarded as positive proof of virginity, nor the presence of corpora lutea as always indicating the state of impregnation. The blood-vessels of the ovaries are the same as those iupplying the testes — the spermatic. Function. — The use of the ovaries seems to be to prepare the germ to be fecundated by the male semen. They are regarded as essential in the function of reproduction, since their extirpation is always followed by sterility. FALLOPIAN TUBES. 671 The Fallopian Tubes, (Fig. 211.) — These tubes, named after their discoverer, are situated within the fold of the broad ligament, along its superior border. They are two in number, one on each side of the pelvis, and extend from the superior angles of the uterus, transversely to the distance of from four to five inches, where each ter- minates in a free and fringe-like extremity, called corpus fimbriatwn, consisting of several irregular processes. In this course the tubes have the round ligaments in front, and the ovaria, with their ligaments, behind. The uter- ine extremity has a very small orifice, scarcely admit- ting a bristle, while the outer or ovarian end presents a trumpet-mouth as large as a quill, and, with its processes, receives the name of morsus didboli. These processes or fimbrias are in one or more rows, one of which attaches them to the ovary. The Fallopian tubes are straight *at the inner end, but pursue a tortuous course in their outer portion. Structure. — These tubes have three coats — an outer, loose, and serous, and derived from the broad ligaments ; a mid- dle, fibrous, or fibro-muscular coat, having longitudinal fibres externally, and circular internally, continuous with those of the uterus ; and an internal or mucous coat, which is continuous internally with that of the uterus, and exter- nally with the peritoneum, the only instance of direct continuity between a mucous and serous membrane. This mucous coat is thrown into longitudinal folds, admitting of dilatation, and is covered by an epithelium, both ciliated and columnar. Neither orifice of the Fallopian tube, nor any part of its course has any valve. Function. — The use of these tubes is to transmit the fecundating principle of the male to the ovary, and to con- duct to the uterus the ovum when fecundated. Their use is the same as the oviduct, and it is found that the ovum, in its passage along the Fallopian tube, receives a double envelope — an internal layer, of an albuminous or gelatinoui nature, called the amnion, and an external fibrous layer, called the chorion. The time it takes the ovum to traverse 672 MUSCLES OF THE PELVIS. one of these tubes is estimated at from eight to fourteen days. The uterus has been preparing a membrane, the decidua, which lines its internal surface by the time the ovum arrives. That which covers the uterus is the decidua vera; that which covers the ovum, the decidua reftexa. The placenta is next seen, which is regarded as a joint pro- duction of both the ovum and the mother. SECTION III. MUSCLES OF THE PELVIS. Glutens maximus. — Dissection. — Make an incision round the crest of the ilium to the coccyx, extending downward upon the outer side FIG. 212. of the thigh, about three or four inches ; make another incision from the middle of the crest of the ilium to the trochanter ma- JOT. Dissect off the ^^•BPHMRiil * integuments, adipose structure, and fascia, in the direction of the last incision, which is the course of the fibres of the muscle, and which will expose its whole extent. It arises from the posterior part of the crest of the ilium from the contiguous dorsum of this bone, from the side of FIG. 212 represents the Muscles of the Pelvis on its exterior, a Posterior •urface of the sacrum. 6 Os-coccygis. c Crest of ilium, d Trochanter ma- jor, e Linea aspera. / Gluteus maximus. g h Gluteus medius. i Vastui externus. j Greater sacro-sciatic ligament, k Tuberosity of the ischium. i Pyriformis. m Gemellus superior, o Gemellus inferior. « Obturator inter- nus. p Obturator externus. q Quadratus femoris. r Insertion of gluleuf maximus. s Biceps femoris. t Semi-tendinosus. u Semi-membranosus. 9 Gracilis. MUSCLES OF THE PELVIS. 673 the sacrum and coccyx, and from the great sacro-sciatic ligament, by fleshy and aponeurotic fibres. Its fibres are collected into distinct fasciculi, presenting a thick, strong, and large quadrangular fleshy mass of muscle, of a rough and coarse appearance, descending obliquely downward and forward to terminate in a broad, thick tendon, which is inserted into the upper third of the linea aspera, also into a rough ridge, leading from this line to the trochanter, and into the fascia lata over the vastus externus. The fasci- culi of this muscle are separated by processes of the fascia fernoris, and it almost entirely covers all the muscles on the back of the pelvis together with the origin of the ham- string muscles. A large bursa is observed between the tendon and vastus externus, and a third where this muscle glides over the tuberosity of the ischium. Function. — To extend the thigh and rotate it outward ; also to support the trunk in the erect position. Turn down the gluteus maximus upon the thigh, and we expose the gluteus medius, gluteus minimus, pyriformis, gemelli, obturator, and quadratus femoris. The gluteus medius (Fig. 212) is a triangular, flat mus- cle, having its anterior portion uncovered by the gluteus maximus. It arises from the outer edge of the whole of crest of the ilium, except its posterior part, by fleshy and aponeurotic fibres ; also from the dorsum of the ilium, be- tween its crest and semicircular ridge, and from the strong fascia which covers it. It is inserted by a broad, thick ten- don, into the upper and outer part of the trochanter major, and into a portion of the shaft of the bone. Function. — To extend the thigh and turn it outward. A bursa is seen between the tendon of this muscle and the tendinous insertion of the rotators. The gluten minimus, (Fig. 212,) so named from being the smallest of the three glutei, is seen by raising the last. It arises from the dorsum of the ilium, between the semi- circular ridge and the margin of the acetabulum, and ending in a round, strong tendon, is inserted into the upper, ante- rior portion of the trochanter major, having a bursa between 43 674 MUSCLES OF THE PELVIS. it and the insertion of the glutens medius. Function. — The same as the last, and also to strengthen the ilio-femoral articulation. The pyriformis (Fig. 212) is a triangular muscle, which arises by its base within the pelvis, fleshy and tendinous, from the second, third, and fourth divisions of the sacrum, and forms a thick, conical belly, which passes out at the upper part of the great sciatic notch, receiving fibres in its course, from the sciatic ligament and posterior inferior part of the ilium. It is inserted by a round tendon into the su- perior portion of the fossa at the root of the trochanter major. Function. — To rotate the thigh outward. The gemelli (Fig. 212) are two small muscles. The supe- rior arises from the spine of the ischium, the inferior from the tuber of the ischium and the great sciatic ligament- They run parallel to each other, and both are inserted into the root of the trochanter major. Function. — To rotate the thigh outward, and strengthen the capsular ligament. The obturator internus (Fig. 212) arises from the pelvic surface of the obturator ligament, except at the superior part where the obturator vessels and nerve pass out ; also from the obturator margin and plane of the ischium. Its fibres converge to a flat tendon, which passes through the lesser sciatic foramen, and thence goes between the gemelli muscles to be inserted into the fossa at the root of the great trochanter. As this muscle passes over the ischium, there is found interposed a bursa, and another between the tendon and the gemelli. Function. — To rotate the thigh outward. Obturator Externus. — Dissection. — Most of the muscles on the anterior and internal thigh at the superior part must be removed, when this muscle will be seen to arise fleshy from the anterior surface of the obturator ligament, except where the obturator vessels pass out, and also from the surrounding margin of the thyroid foramen. The fibres converging, end in a tendon which passes outward and ackward in a groove behind the neck of the femur, to be FASCIA OF THE PELVIS. 675 inserted into the lower part of the fossa, at the root of the great trochanter. Function. — To rotate the thigh outward. The Quadratics Femoris (Fig. 212) is situated lower down than the other rotators, and arises from the external surface of the tuber ischii fleshy and tendinous. Its fibres run transversely, and are inserted fleshy and tendinous into the back part of the great trochanter and intertrochanteric line. A bursa is found between this muscle and the little trochanter. Function. — To rotate the thigh outward. The psoas muscles and iliacus internus are noticed in another place. SECTION IV. FASCIA OF THE PELVIS. The pelvic fascia is regarded as a continuation of the iliac, which descends into the pelvis from the brim, to which it is attached, to about midway its depth, where it divides into two laminae, the superior pelvic aponeurosis or vesical fascia, and the lateral pelvic aponeurosis or obtu- rator fascia. The superior or vesical fascia is seen by removing the peritoneum, when it will be found to line the inner surface of the levator ani muscle, and to assist in closing the pelvis, fixing its several viscera, and resisting pressure from the abdominal muscles. It is reflected from the inferior edge of the symphysis pubis upon the neck of the bladder and prostate gland, constituting the anterior true ligaments of the bladder. Upon this organ it is reflected laterally, forming its lateral ligaments. Posteriorly it becomes thin and cellular, and is lost upon the sacrum. Mr. Tyrrell notices a reflection of this fascia between the bladder and rectum, which he terms recto-vesical. Another process, the rectal fascia^ descends, and covers the lower part of the rectum behind and laterally. This latter fascia, with the recto-vesical in front, forms a complete aponeurotic invest- ment for the lower portion of the rectum. 676 PERINEUM OF THE MALE. The obturator fascia covers the obturator interims muscle, and is upon the outside of the levator ani. This fascia is connected with the great sciatic ligament, and the rami of the pubis and ischium, and is continuous with the triangu- lar ligament. It forms a sheath for the pudic vessels and nerves, and sends off a process which covers the lower or perineal surface of the levator ani, called the ischio rectal or anal fascia. Triangular Ligament, or Ligament of Camper, or Deep Perineal Fascia. — This ligament consists of a strong apon- eurosis, forming a septum between the pelvis and perineum. It is situated below the symphysis pubis, attached to and filling up the space between the rami of the pubis and ischium. Its shape is triangular, the base being below and the apex above. It consists of two larninge, one ante- rior, upon which the bulb rests, the other posterior, sur- rounding the membranous part of the urethra, and enclos- ing the prostate gland. This ligament is penetrated by the urethra about an inch below the pubic arch. Between its two laminee, at the inferior margin, and posterior to the bulb of the ure- thra, are seen Cowper's glands, already described. At the upper part of this ligament, between its layers, and imme- diately below the symphysis, about half an inch broad, thick and strong, and stretching from side to side of the rami of the pubis, is another called the sub or inter-pubic ligament. These ligaments help to form the anterior boundary of the pelvis, besides giving passage to the ure- thra, and supporting and fixing its bulb. SECTION V. THE PERINEUM OF THE MALE. The different elements composing the perineum consist of fascia, muscles, blood-vessels, and nerves. Dissection. — The subject is placed as in the operation for lithotomy, that is, upon the back, with the thighs and knees bent upon the trunk, and the feet and hands bound together. The knees being thrown apart, and the scrotum PERINEUM OF THE MALE. secured upward by means of the double tenaculum, an in- cision is made transversely along the base of the scrotum ; FIG. 213. 1716 "7/7 then two vertical incisions running from the extremities of the first, along the rami of the pubis and ischium, to a point corresponding to the apex of the coccyx. These two latter incisions, being united at their coccygeal end, will thus complete and describe the perineal space. This space has along its median line a prominent ridge termed the raphe of the perineum, which is found to extend along the scrotum and penis as far as the prepuce. The integument should first be dissected off. The fascice of the perineum consist of the superficial, middle, and deep. The superficial is seen immediately on removing the integuments, and consists of condensed cel- lular tissue, continuous with that upon the inner side of the thigh, attached to the rami of the pubis and ischium, and about the anus containing a quantity of soft, granular, adipose matter. This fascia gives a covering to the mus- cles of the perineum ; or more properly speaking, on being removed, is found to cover another fascia, which has been called the middle, and consists of a semi-transparent and FIG. 213 represents the Muscles of the Male Perineum. 1 Accelerator urinae. 2 Erector penis. 3 Transversus perinei. 4 Sphincter ani. 5 Leva- tor ani. 6 Coccygeus. 7 Gluteus maximus. 8 Adductor tertius or magnus. 9 Adductor brevis. 10 Adductor primus or longus. 17 17 Corpora cavernosa. 16 Urethra. 14 Spermatic cord. 678 MUSCLES OF THE PERINEUM. fine but dense aponeurosis, forming the immediate cov- ering to the muscles. This, however, is sometimes called the deep fascia, though this latter term, to avoid confusion, has been restricted to another fascia still deeper, the tri- angular ligament , which has been already described. The muscles of the perineum are seen on removing the fascia, and are ten in number, the — Sphincter externus, Transversus perinei, Sphincter internus, Coccygeus, Erectores penis, Levatores-ani. Acceleratores urinae, The sphincter externus, or ani, (Fig. 213,) is a cutane- ous muscle, surrounding the anus, and presenting a flat, thin, pale, and elliptical plane of fibres. It has two fixed points of attachment — one to the os-coccygis and recto-coc- cygeal ligament behind, which is called its origin ; the other to the central point of union of the perineal muscles in front, and also to the superficial fascia and raphe, which is the insertion. On surrounding the anus, it expands outward nearly to the tuberosities of the ischia. Function. — To .-close the anus, and draw the bulb of the urethra back, or the coccyx forward. Sphincter internus, or orbicularis. — This muscle surrounds the lower portion of the rectum, is in close contact with the mucous membrane, and is regarded simply as a contin- uation and thickening of the circular muscular coat of this intestine. Function. — To assist in closing the anus. The erector or compressor penis (Fig. 213) arises, fleshy and tendinous, from the inner and anterior surface of the tuber ischii. Its fibres adhere to the rami of the ischium and pubis, and end in a tendinous expansion which is lost or inserted into the fibrous membrane of the corpus caver- nosum or crura penis. This muscle is long and narrow. Function. — To draw down and compress the penis, and thus aid in its erection by preventing the return of the blood, though its use, by some, is not considered as fully understood. MUSCLES OF THE PERINEUM. The accelerator urince, or ejaculator seminis, (Fig. 213,) is situated upon the back part of the corpus spongiosum urethras and its bulb. It arises, along with its fellow, from the central line or raphe, forming a thin muscle upon the middle of the perineum, the fibres of which diverge Jike the feathers of a quill, the posterior covering the bulb, being inserted into the triangular ligament, and sometimes attached to the rami of the ischium and pubis. The mid- dle fibres are short and surround the urethra ; while the anterior are the longest and ascend upon the crura of the penis. Function. — To expel the semen and the last drops of urine. The transversalis perinei (Fig. 213) arises from the tuberosity of the ischium at its inner side ; the fibres run transversely and are inserted into the central point of the perineum, behind the acceleratores. This muscle is fre- quently indistinct and sometimes absent. Function. — To fix the bulb and dilate it. A fasciculus of fibres, called transversus perinei alter, is sometimes seen in front of the transversalis, and is regarded as a portion of the accelerator urinaa, being inserted into the common central point and side of the bulb. Its function is the same as that of the transversalis. The coccygeus (Fig. 213) is a small, triangular muscle, seen within the pelvis. It arises tendinous and fleshy from the spine of the ischium, and is inserted into the side of the coccyx and extremity of the sacrum. Function.— To bring the coccyx forward, and to assist in closing the lower and posterior part of the pelvis. The levator ani (Fig. 213) is a broad, thin muscle, form- ing a great part of the floor of the pelvis. It arises fleshy from the back part of the symphysis pubis, from the supe- rior margin of the thyroid foramen ; from the obturator fascia as it stretches in the form of a semilunar chord from the upper margin of the thyroid foramen towards the spine of the ischium ; fleshy and tendinous from the spine and inner surface of the ischium. The fibres of this muscle converge and descend backward. Its anterior fibres, which 680 MUSCLES OP THE PERINEUM. descend along the side of the lower fundus of the bladder, the membranous part of the urethra, and the prostate gland, are inserted into the central point of the perineum. The middle fibres are inserted, according to Dr. Horner, into the semicircumference of the rectum, between the lon- gitudinal fibres of the latter and the circular fibres of the sphincter ani, while the posterior fibres are inserted into the os-coccygis and back part of the rectum. Function. — To draw the rectum forward and assist in ex- pelling the fasces, urine, and semen. The compress ores or levatores urethra, described by Mr. Wilson, and the transverse compressors of Mr. Guthrie, are regarded as nothing more than the anterior portions of the levator ani. In the female perineum, the erector ditoridis muscle cor- responds with the erector penis, and the sphincter vaginae, with the accelerator urince. Blood-vessels of the perineum. — The arteries come from the internal pudic, and consist of, 1. Inferior hcemorrlioidal, going to the side of rectum and anus. 2. Superficial peri- neal. 3. Transverse perineal. These two latter supply the perineal space and go to the scrotum. 4. Artery of the bulb, which passes between the layers of the triangular ligament and goes to the bulb and corpus spongiosum. The veins corresponding to the arteries terminate in the internal iliac vein. Nerves of the Perineum.^-These come from the pudic nerve, which arises from the lower part of the sacral plexus and takes the course of the internal pudic artery. The in- ferior branch of the pudic is the proper perineal nerve, and gives off the external perineal, superficial perineal, and nerve of the bulb. SUMMARY OP MUSCLES OF THE TRUNK. 681 SUMMARY OF MUSCLES, BLOOD-VESSELS, AND NERVES OF THE TRUNK. Under the arrangement which we have adopted the mus- cles of the neck form a part of those belonging to the trunk. The order will be, 1. The neck, 2. The back, 3. Abdomen, 4. Chest, 5. Pelvis. MUSCLES OF THE NECK. To the neck proper are assigned 18 pais of muscles, ar- ranged, agreeably to Mr. Harrison, into four groups, besides which there are five other groups, including twenty-one pairs and two single muscles; making in all thirty-nine pairs and two single muscles. FIRST GROUP— Two pairs of Muscles. Platysma-myoides. Sterno-cleido mastoideus. SECOND GROUP — Four pairs. Sterno-hyoideus. Sterno-thyroideus. Thyro-hyoideus. Omo-hyoideus. THIRD G ROUP— Five pairs. Digastricus. Mylo-hyoideus. Genio-hyoideus. Hyo-glossus. Genio-hyo-glossus. FOURTH GROUP — Seven pairs. Longus colli. Rectus capitis anticus major. Ilectus capitis anticus minor. Rectus capitis lateralis. Scalenus anticus. Scalenus medius. Scalenus posticus. FIFTH GROUP — Three pairs. Stylo-hyoideus. Stylo-glossus. Stylo-pharyngeus. SIXTH GROUP-— four pairs. Lingualis. Superficial lingual. Transverse lingual. Vertical lingual. These are the muscles proper of the tongue'. SEVENTH GROUP — Three pairs. Constrictor pharyingis inferior. Constrictor pharingis medius. Constrictor pharyngis superior. Muscles proper to the pharynx. EIGHTH GROUP — Four pairs and a single muscle. Levator palati. Circumflexus, or tensor palati. Constrictor isthmi-faucium, or palato- glossus. Falato-pharyngeus. Azygos-uvul®, a single muscle. Muscles proper of the Dalate. NINTH GROUP — Set-en pairs and a single muscle. Crico-thyroideus. Crico-arytenoideus posticus. Crico-arytenoideus lateralis. Thyro-arytenoideus. Arytenoideus obliquus. Arytenoideus transversus, a single mus- cle. Aryteno-epiglottideus. Thyro-epiglottideus. Muscles proper of the larynx. 682 SUMMARY OF MUSCLES OF THE TRUNK. MUSCLES OP THE BACK, ARRANGED INTO SIX LAYERS. FIRST LAYER — Two pairs of Muscles. Trapezius. Latissimus dorsi. SECOND LAYER — Three pairs- Levator anguli scapula. Rhomboideus minor. Rhomboideus major. THIRD LAYER — Four pairs. Serratus posticus superior. Serratus posticus inferior. Splenius capitis. Splenius colli. FOURTH LAYER — Seven pairs. Sacro-lumbalis. Longissimus dorsi. Spinalis dorsi. Cervicalis ascendens. Transversalis colli. Trachelo-mastoideus. Complexus. FIFTH LAYER — Seven pairs. Rectus capitis posticus major. Rectus capitis posticus minor. Rectus capitis lateralis. Obliquus capitis superior. Obliquus capitis inferior. Semi-spinalis dorsi. Semi-spinalis colli. SIXTH LAYER — Five pairs. Multifidus spinae. Levatores costarum. Supra-spinales. Inter-spinales. Inter-transversales. MUSCLES OP THE ABDOMEN SEVEN PAIRS. Obliquus externus abdominis descen- dens. Obliquus internus abdominis ascendens. Transversalis. Cremaster. Rectus abdominis. Pyramidalis. Quadratus lumborum. MUSCLES OF THE CHEST — FOUR PAIRS, PROPERLY SPEAKING. Pectoralis major. Pectoralis minor. Subclavius. Serratus major anticus. Intercostales externi. Intercostales interni. Levatores costarum. Triangularis sterni. Diaphragm. MUSCLES OF THE PELVIS. THOSE OF THE INTERIOR ARE, Psoas magnus. Psoas parvus. Iliacus internus. THOSE OF THE EXTERIOR ARE, Gluteus maximus. Gluteus medius. Gluteus minimus. Pyriformis. Gemellus superior. Gemellus inferior. Quadratus femoris. Obturator externus. Obturator internus. THOSE OF THE INFERIOR PELVIS ARE, Sphincter ani. Transversus perinei. Accelerator urina3. Erector penis. Levator ani. Coccygeus. Compressor urethrae. Erector clitoridis. Constrictor vaginae. BLOOD VESSELS AND NERVES OF THE TRUNK. 683 BLOOD-VESSELS OF THE TRUNK. For a brief summary of the blood-vessels of the trunk, we refer to the following figure, 214, and its explanation ; and for further detail to figures 8, 9, and 120. FIG. 214. a Aorta, its commence- ment, b Thoracic aorta. c Abdominal aorta, d Ar- teria innominata. e Com- mon carotid, f Superior thyroid artery, g Right subclavian. h Vertebral. 1 i Inferior thyroid, j An- terior cervical, k Trans- verse cervical. I Superior scapular, m Superior in- tercostal, n Internal mam- mary, o Left carotid, p Left subclavian. q Medi- astinal. r Upper intercos- tal arteries, s (Esophageal. t Phrenic, u Lower in- tercostal artery, v Ccel- iac, its division into the gastric, hepatic, and sple- nic arteries, to Superior mesenteric. x Emulgent. y Inferior mesenteric. z Aorta, its division into the primitive iliacs. a a Mid- dle sacral, b b Common iliacs. c c External iliacs. d d Epigastric, e e Circumflexa ilii. // Internal iliac, g g Ilio-lumbar. h h Lateral sacral, ii Gluteal. jj Vesical. k k Obturator. I I Ischiatic. m m Internal pudic. NERVES OF THE TRUNK. See figures 14, 152, 155, 203, 204, and 153, with their explanations. 684 RELATIONS OP THE MOUTH. SECTION VI. ANATOMICAL AND PHYSIOLOGICAL RELATIONS OF THE MOUTH WITH THE DIFFERENT ORGANS OF THE TRUNK. The several organs of the trunk comprise the digestive, pulmonary, urinary, and generative. The mouth has a relation more or less intimate, both by structure and function, with all these various organs. With the digestive and pulmonary the relation is direct and inseparable. The same mucous membrane, for in- stance, which lines the mouth, is traced down the oesopha- gus into the stomach, and through the whole alimentary canal. It is continued also into the various excretory ducts of the salivary glands, liver, pancreas, and mucous follicles, all of which organs pour their several fluids into the mouth and digestive tube. This same mucous mem- brane is traced from the mouth, in another direction, into the larynx, trachea, bronchi, and lungs. The mucous membrane is also found in the kidneys, ureters, and blad- der, the genital organs of the male and female, receiving here the name of the genito-urinary mucous membrane, which, however, is not directly traceable to the mouth. The cellular tissue forms another element of anatomical continuity between the mouth and the various organs. The par-vagum, one of the divisions of the eighth pair of nerves, forms a great chain of nervous connection between the posterior mouth, and the oesophagus, stomach, larynx, lungs, and brain. The fifth pair of nerves, which are mostly nerves of sensibility, bountifully supply all the organs of the mouth, and connect directly with the brain, spinal marrow, and the several organs of sense. The portio dura of the seventh pair, also forms an element of nervous com- munication between the mouth and other parts. The blood- vessels, supplying the mouth, come from the same great arterial tube which supplies all the organs of the body. The physiological relation of the mouth with the various organs is as close as the anatomical. RELATIONS OF THE MOUTH. C85 The digestive function, for instance, comprises a series of sub-divisions or functions, constituting so many links or stages, each one of which is essentially related with, and dependent upon every other and the whole; and the whole upon each, for the completion and perfection of this won- derful and complicated process, styled digestion. The function of digestion begins in the mouth by sub- jecting the crude material of nutrition to the several opera- tions of mastication, insalivation, and deglutition, and the aliment having arrived in the stomach, the function is there continued, by converting this aliment into chyme, whence it is conducted into the small intestine, and there undergoes its final change, by being formed into chyle, and thus completing the whole process of digestion. But the relation of the mouth, in this series of physio- logical actions, does not stop here ; for we follow the chyle through the great trunk of the absorbent system, into the left subclavian vein, thence through the heart to the lungs, where, with the venous blood, and by atmospherical agency, it undergoes its final and most perfect change ; in other words, is formed into arterial Wood, the only and proper pabulum by which the mouth, as well as the whole body with all its organs, is built up and sustained. To accomplish this result, we now trace this fluid blood from the lungs into the heart and arteries, by which latter it is distributed over the whole body, and consequently brought back to supply the mouth, the point where began the first change in this most beautiful series of operations so essential to the formation of this vital fluid. These several relations, anatomical and physiological, thus briefly sketched, which the mouth has with the vari- ous organs, shows an intimacy of connection, not only close, but inseparable. Hence the dental student will perceive the absolute necessity of not confining his anatomical studies solely to the mouth, but of examining studiously every organ and portion of the body with which the mouth has any relation, as necessary steps to becoming completely master of his profession. PART FOUKTH. THE LANGUAGE OF ANATOMY. III. THE EXTREMITIES. PART FOUKTH. SUPERIOR EXTREMITY. THE SUPERIOR EXTREMITY COMPRISES BONES, LIGAMENTS, MUSCLES, FASCIJE, BLOOD-VESSELS, AND NERVES, AND WILL BE EXAMINED UNDER THESE SEVERAL HEADS RESPECTIVELY. CHAPTER I. THE BONES. THE Bones are arranged into those of the .Shoulder, Arm, Forearm, and Hand. SECTION I. BONES OF THE SHOULDER. The bones of the shoulder are two in number : 1. The Scapula ; 2. The Clavicle. THE SCAPULA OR SHOULDER BLADE, (Fig. 215.) The Scapula is situated upon the posterior and superior part of the chest. Its form is triangular, and it presents two surfaces, three edges, and three angles. The anterior surface looks toward the ribs, and is also the internal sur- face or subscapular fossa. It is concave, divided by several irregular lines, and occupied by the subscapular muscle. The posterior or external surface is the dorsum, and is cut transversely into two unequal parts by a very prominent process called the spine of the scapula. This spine proceeds forward, and terminates in the aero- mlon process, which is flattened superiorly and inferiorly, and overhangs the shoulder joint. This spine also divides the dorsum into the sityra and infra spinal fossce^ which contain the supra and infra spinal muscles. The upper edge of the spine has the trapezius attached to it, the lower edge the deltoid muscle. 44 690 THE SCAPULA. The superior edge or costa is situated between the ante- rior and superior angles, is thin and short; and has at its fore-part a notch, which is formed into a foramen by a ligament, and transmits the supra-scapular nerve. The F[G. 215. oino-hyoid, supra-spinatus, and sub-scapular muscles are also at- tached to this edge. At its anterior portion the cora- coid process arises. This is long and narrow, runs upward and forward, and bounds the glenoid cavity internally. Its superior surface is rough for the attach- ment of ligaments, the inferior is smooth for the sub-scapular mus- cle. The extremity of this process frequently presents three distinct surfaces, the inner of which has the pectoralis minor inserted into it; the middle gives origin to the coraco-brachialis, and the outer to the short head of the biceps. The anterior or axillary edge looks downward and back- ward, and extends from the anterior to the inferior angle. It is the thickest of the three edges, and gives attachment to the teres major, teres minor, and long head of the triceps. The posterior or vertebral edge, called also the base, extends from the superior to the inferior angle, and is the longest of the three margins. Below the spine are attached to it the rhomboideus major, opposite the origin of the spine the rhomboideus minor, above the spine the levator scapulae, and along its whole extent the inser- tion of the serratus major anticus. At the junction of the superior costa and the base is the superior angle. At the FIG. 215 represents the Scapula, a Supra-spinal fossa, b Infra-spinal fossa, c Superior edge or costa. d Coracoid notch, e Anterior or inferior edge. / Glenoid cavity, g Inferior angle, h Neck, i Posterior edge or base, j Spine of scapula, fc Point of attachment of rhomboideus minor. I Acromion process, m Nutritious foramen, n Coracoid process, o Point where the deltoid is attached. THE CLAVICLE. 691 union of the superior and anterior costa is the anterior angle, which contains the glenoid cavity. This cavity is ovoidal, deepened hy the glenoid ligament, and is hroader below than above. It is covered with cartilage, and has the long head of the biceps arising from its superior mar- gin. It articulates with the head of the humerus. Behind this cavity the bone contracts, and is called the neck or cervix. The inferior angle is formed by the junction of the base and anterior costa ; it presents a flat surface for the origin of the teres major. Structure. — The scapula is composed of two compact layers with cellular substance between them. The latter is most abundant in the processes, while in the centre of the dorsum the bone is diaphanous. Its development takes place from several points, one for each of the processes, one for the centre of the body, one for the base, and one for the inferior angle. An ossific centre is noticed in the infra spinal fossa about the seventh or eighth week, during the first year in the coracoid process, at puberty in the acromion process, in the fifteenth year at the inferior angle, during the seventeenth or eighteenth year at the base, and about the twentieth or twenty-fifth year the bone is found complete. THE CLAVICLE OR COLLAR BONE. The clavicle is situated transversely, between the upper extremity of the ster- FIG. 216. num and the acro- mion process of the scapula. Its shape is that of the italic s. It is longer in the female than the male, and consists of a body and two extremities. The body is rather cylindri- cal at the sternal, and flattened at the acromial end. Its FIG. 216 represents the Clavicle, a Anterior surface, b Point of attach- ment of sterno-cleido mastoid muscle, c Sternal end of Clavicle, d Acro- mial end. e Articular surface. / Where the conoid ligament is attached. g Where the rhomboid ligament is attached. 692 HUMERUS. upper surface is smooth. Its lower presents a ridge for the attachment of the rhomboid or costo-clavicular liga- ment,, and a groove for the subclavian muscle. The sternal portion is convex in front, and concave behind. The hu- meral end is just the reverse. Two-thirds of the anterior margin give origin to the pectoralis major, the rest to the deltoid muscle. The posterior margin has one or more foramina for nutritious vessels. The sternal superior sur- face gives origin to the sterno-cleido-mastoideus. The sternal extremity is triangular, thick, and forms the ar- ticulating surface. Its margin has ligaments attached to it. The acromiol end is flat, presents an articular surface, and covers the coracoid process. Its Structure is compact and cellular. The former is very condensed and strong in the centre of the bone ; the latter abounds mostly at the extremities. Function. — To support the scapula and prevent its fall- ing forward or inward, and also to protect the vessels and nerves as they pass to the extremity. Its development is from two points of ossification, (one for the body and the other for the sternal end) and is found to be very perfect in the foetus. Ossification begins in the clavicle sooner than in any other bone, as early even as the fifth week of intra- uterine life. The sternal epiphysis is ossified during the fifteenth and twentieth years. It is articulated to the ster- num and scapula. SECTION II. THE HUMERUS OR ARM-BONE. The humerus is the largest bone in the upper extremity, and is situated between the scapula above, and the radius and ulna below. It consists of a body and two extremities. The body or shaft is cylindrical ; its upper anterior fourth is divided by the bicipital groove which lodges the long head of the biceps muscle. The anterior edge of this groove has the pectoralis major inserted into it ; its posterior edge receives the insertions of the latissimus dorsi and teres major muscles. About the centre of this bone is seen a rough tri- IIUMERUS. 693 *•* angular surface for tlie insertion of the deltoid muscle, and about the same point an oblique vascular foramen. The pos- terior surface is smooth, and covered by the triceps muscle. The upper or scapular extremity presents a smooth, hemi- spherical surface, covered with cartilage, and called the head. It articulates with the glenoid cavity FIG. 217. of the scapula. Just below and around the head there is a furrow or contraction of the bone called its neck. It is rough and gives attachment to the capsular ligament. Below the neck the humerus swells into two pro- cesses called tuberosities. They are two in number, external and internal, or the greater and lesser. The external presents three de- pressions ; the anterior p, middle, and posterior^ To the anterior the supra spinatus, to the middle the infra spinatus, and to the posterior the teres minor muscles are attached. The in- ternal tuberosity gives insertion to the tendon of the subscapularis. The inferior extremity of the humerus is, flattened, and is bounded externally and inter- nally by two ridges for the attachment of •* muscles and the intermuscular ligaments. These ridges lead to the two projections called condyles. The internal condyle is most prominent and has attached to it the inter- nal lateral ligament, and the pronator and flexor muscles. The external condyle, less prominent, gives attachment to the external lateral ligament and to the supinator and extensor muscles. Between these two condyles a smooth articulating surface is observed, separated by a ridge. The FIG. 217 represents the anterior surface of the Humerus. a Shaft or body of the Humerus. 6 Head, c Anatomical neck, d Greater tuberosity. e Lesser tuberosity. / Bicipttal groove, g- Point of insertion for the pectoralis major. h Internal bicipital ridge, i Point where the deltoid is inserted, j Nutritious foramen, k Articular surface for the radius. I Articular surface for the ulna, m External condyle. n Internal condyle. o p Condyloid ridges, q Lesser sigmoid cavity. 694 RADIUS. inner portion, called the trochlea, is the larger, and articu- lates with the ulna. The outer receives the head of the radius. Ahove the trochlea, and in front of the humerus, is the anterior or lesser cavity for receiving the coronoid process of the ulna. Behind the humerus, and above the trochlea, is the posterior or greater cavity for receiving the olecranon process of the ulna. Between these two cavities the hone is transparent, and sometimes wanting. Structure. — The humerus consists of compact structure in its body, and is cellular at its extremities. It contains a large medullary canal. It is articulated to the scapula, radius and ulna. Its development is from eight points, viz : one for the body, one for the head, one for each tuberosity, one for the trochlea, one for each condyle, and one for the small head. Ossification is noticed to begin shortly after that of the clavicle. At birth the extremities are found cartilaginous,, while the bony shaft is nearly complete. From the close of the first and during the second and third years, ossific centres are observed in the head and tuberosi- ties — during the third and sixth years the trochlea and small head of the humerus — during the fifth to the seven- teenth year ossification appears in the condyles, and the bone is found complete about the twentieth year. SECTION III. BONES OF THE FOREARM — THE RADIUS, (Fig. 218.) The radius is situated upon the outer side of the ulna, the palm of the hand looking upward, and is the shorter bone of the two occupying the forearm. It consists of a body and two extremities. The body or shaft of the radius presents three surfaces, and is rather triangular in shape. The anterior surface is covered below by the pronator quadratus, and is there broad ; a little Above its centre is seen the orifice of an oblique vascular •canal. The posterior surface is convex above and gives attachment to the supinator brevis, and is concave in the middle for the extensors of the thumb. The external surface is round, and in its centre is rough for the insertion of the pronator teres. RADIUS. 695 The upper extremity, styled the head, presents two smooth articulating surfaces; the one, a superficial cavity, and superior, articulates with the small head FIG. 218. of the huinerus; the other forms the circum- ference and articulates with the lesser sig- moid cavity of the ulna. Below the head the bone contracts, and is called the cervix or neck. Below the neck, or where the latter and the body unite, is the tubercle which gives insertion to the tendon of the biceps. It is also covered by a bursa. The lower or carpal extremity is the larger of the two, and is widest transversely. It is bounded externally by the styloid process, which gives attachment to the external lateral ligament of the wrist. Internally is a smooth concave surface for articulating with the lower end of the ulna. The carpal surface is smooth and divided by a ridge into two unequal articulating portions ; the outer and larger is for the scaphoid bone, the inner receives the lunar. The margin of the carpal surface presents a prominent ridge to which the capsular ligament is attached. On the posterior surface of this car- pal extremity several grooves are noticed. At the side and base of the styloid process is a groove for the tendons of the extensor ossis metacarpi, and minor pollicis muscles. Next to this is a larger groove for the tendons of the exten- sor carpi radialis longior and brevior. On the middle, and next in order, is a groove for the extensor major pollicis, and on the ulnar side of this is another and larger for the extensor communis and indicator. Structure. — Cellular in the extremities and compact in the centre. FIG. 218 represents the Radius'and Ulna, a Shaft of the ulna. 6 The greater sigmoid cavity, c Lesser sigmoid cavity. dOlecranon process- « Coronoii process. /Nutritious foramen, g Sharp edge for attachment of interosseous membrane, h Lower extremity of ulna, t Styloid process, j Shaft of radius, fc Its head. /Neck, m Its tuberosity. n Oblique line, o Lower extremity of radius, pits styloid process. 696 ULNA. Its development is from three points, one for the body and one for each extremity. Ossification begins in the radius during the sixth week, shortly after that of the humerus. At birth both extremities are cartilaginous. In the lower end an ossific point is seen about the close of the second year, and in the upper end from the fifth to the seventh, the bone being completed about the twentieth year. It is articulated to the humerus, ulna, scaphoid and lunar bones. THE ULNA, (Fig. 218.) The ulna is situated at the inner side of the radius, the palm of the hand being uppermost. It is triangular in shape, and consists also in a body and two extremities. The body presents three ridges and three surfaces. The external or radial ridge is most prominent, runs the greater part of the length of the bone and gives attachment to the inter- osseous ligament ; the anterior ridge is round, and has the flexor profundus and pronator quadratus attached to it; the posterior ridge is distinct above and gives attachment to the anconeus. Between these ridges are so many sur- faces all covered by muscles. The anterior surface has a foramen a little above its centre, looking obliquely upward, and conducts the nutritious vessel. The superior extremity is much larger than the lower and forms the greater por- tion of the elbow-joint. It presents two processes ; the one anterior and smaller, called coronoid; the other posterior and much larger, termed olecranon. The coronoid process is triangular and sharp, and is received into the anterior cavity of the lower end of the humerus. Its anterior sur- face gives insertion to the brachialis anticus muscle. Its outer surface is hollowed into the lesser sigmoid cavity, which articulates with the side of the head of the radius. The olecranon process has its posterior surface covered by a bursa, and is rough for the insertion of the tendon of the triceps, and its extremity presents a point which is received into the posterior or greater cavity of the humerus. Between these two processes is a large concave surface, CARPUS. 69 T smooth, and covered with cartilage, called the greater sig- moid cavity, which receives the trochlea of the humerus. This cavity is divided by a vertical ridge, and about its centre by a transverse ridge, which terminates internally in a notch, in which fatty matter is found. The inferior or carpal extremity is small, and presents a projecting process, called the styloid, to which the internal lateral ligament of the wrist is attached. External to this process is a round smooth head for articulating with the small cavity on the inner side of the radius; and between these two processes, on the back of the ulna, is a groove for the passage of the tendon of the extensor carpi ulnaris. Structure. — Same as the radius. Like that bone, it is developed from three points of ossification. Ossification begins in the ulna during the sixth week, shortly after it takes place in the radius and humerus. At birth both extremities are cartilaginous. The lower end has in its centre an ossific point about the fourth or fifth year. The olecranon is ossified from the seventh to the tenth, and the bone is completed about the twentieth year. It is articulated to the humerus and radius. SECTION IV. THE HAND. The Hand is composed of the carpus, metacarpus, and phalanges. THE CARPUS OR WRIST, (Fig. 219.) The carpus consists of two rows of bones, eight in number. The first row contains the os scaphoides, lunare, cuneiforme, and pisiforme, which are adjacent to the bones of the forearm. The second row is next to the metacarpus, and contains the trapezium, trapezoides, magnum and unciforme. The 05 scai^lioides, (os naviculare,) so called from its fan- cied resemblance to a boat, is situated upon the radial side, and is the largest bone in the upper row. Its upper sur- 698 CARPUS. face is convex and articulates with the radius. Its lower surface is concavo-convex and articulates with the trape- zium and trapezoid. Its ulnar or inner surface articulates FIG. 219. with the os-lunare and os mag- num, while its external or radial face gives attachment to the ex- ternal lateral ligament. The os-lunare, so called from its semi-lunar shape, is convex ahove to receive the radius, and concave helow to articulate with the magnum and unciforme. Its ulnar surface joins the cuneiform, its radial the scaphoid. The os-cuneiforme, so named from its wedge-like shape, is on the ulnar side of the lunar, and articulates with it. The lower surface is concave, and articulates with the unci- forme, and its anterior surface is flat and smooth where it joins the pisiforme. The os pisiforme, so called from its resemblance in size and form to a pea, is the smallest bone in the wrist, and is situated upon the palmar surface of the last, with which it is articulated. It gives insertion to the flexor carpi ulnaris above, and origin to the abductor minimi digiti below. The trapezium is the first bone on the radial side of the second row; it is concave above to receive the scaphoid, and below it joins the metacarpal bone of the thumb. Internally it articulates with the trapezoides and second metacarpal bone ; on its anterior surface is observed a groove for the tendon of the flexor carpi radialis. The trapezoides is smaller than the last, with which it articulates, and of very irregular shape. Above it is con- FIG. 219 represents the Carpus, a Ulna, b Radius, clnter-articular-fibro cartilage, d Metacarpal bone of the thumb, e Metacarpal bone of the first finger. /Metacarpal bone of the second finger, g Metacarpal bone of the third finger, h Melacarpal bone of the fourth finger. S Scaphoides. L Lu- nare. C Cuneiforme. P Pisiforme. T T Trapezium and trapezoides. M Os magnum. U Unciforme.j ^ METACARPUS. 699 cave to join the scaphoid ; below it unites with the second metacarpal bone, and internally with the os magnum. The os magnum, so named from fts size, is situated upon the ulnar side of the last, and is the largest of the bones of the carpus. Its superior surface articulates with the sca- phoid and lunar bones ; its inferior, with the second, third, and fourth metacarpal. Internally it meets the unciform, externally the trapezoides. The dorsal surface is broad, the palmar narrow. The os unciforme, so named from its hook-like process, is the next in size to the os magnum. Its superior surface joins the os-lunare, its external the magnum, its internal the cuneiform, and its base the fourth and fifth metacarpal. Its dorsal surface is rough ; and its palmar presents the hook-like process for the attachment of "'the annular liga- ment. Structure. — The bones of the carpus consist of cellular structure, covered by a delicate lamina of compact bone. They are developed from a single point of ossification, except thounciform, which has two. Ossification is observed to begin in the os magnum and unciforme, at the close of the first year ; in the cuneiform, at the close of the third; in the trapezium and semilunare, in the fifth ; in the scaphoid^ from the sixth to the eighth; in the trapezoides, from the eighth to the ninth, and in the pisiforme in the twelfth year. THE METACARPUS, (Fig. 220.) The metacarpus is situated between the carpus and the phalanges, and consists of five bones. Those corre- sponding to the fingers are parallel to each other ; the one for the thumb' stands out from the rest at an angle. Each metacarpus is composed of a head, shaft and base. The head is at the digital extremity, and articulates with the first phalanx of the fingers ; the shaft is triangular, and marked laterally for the attachment of the interossei muscles ; the base is superior, and articulates with its fel- lows and with the carpal bones. "700 METACARPUS. All the bones of the raetacarpal series have a convexity on their dorsal surface and a concavity on their palmar. FJG. 220. The metacarpal bone of the thumh is the strongest and shortest of the whole; its slightly concave carpal end articulates with the trapezium ; its slightly concave phalangeal end with the first hone of the thumh. On either side of the phalangeal extremity a tubercle is seen on which is placed a sesamoid bone. The second metacarpal bone, or that of the forefinger, is distin- guished from the rest by its greater length ; it articulates at its carpal end by a deep concavity in the middle with the trapezoides. There is a smooth articular face for the trapezium on the one side and the magnum on the other. The base,, on its palmar surface, presents a rough portion for the insertion of the flexor carpi radialis, and a like roughness on the dorsal base for the insertion of the extensor carpi radialis lon- gior. The palmar portion of the shaft is divided by a longitudinal ridge into two surfaces for the interosseous muscles. The third metacarpal bone is the next in size, but rather shorter than the last. Its carpal extremity is triangular, and articulates with the os magnum ; it has on its radial side a tubercle for the insertion of the extensor carpi radialis brevior. On either side of the base are seen articu- lar faces for the second and fourth metacarpal bones. The fourth metacarpal bone is smaller and shorter than the third. Its carpal extremity articulates with the unci- FIG. 220 represents the Metacarpus and Phalanges, a Scaphoides. b Lunare. c Cuneiforme. cJPisiforme. e Trapezium. /Groove for tendon of flexor carpi radialis g Trapezoides. /iOs-magnum. i Unciforme. jj Metacarpal bones. k k Phalanges— first row. 1 1 Phalanges— second row. m m Phalanges— third row. n First phalanx of the thumb, o Last phalanx of the thumb. PHALANGES. 7 01 forme and the magnum, and by its lateral portions with the third and fifth metacarpal bones. The fifth metacarpal bone is smaller and shorter than the fourth. Its carpal extremity presents a double articulating surface, the larger for the unciforme, the smaller for the fourth metacarpal bone. The base presents a tubercle for the insertion of the extensor carpi ulnaris. Development. — Ossification of the metacarpal bones com- mences by two centres — one for the digital extremity, and one for the shaft. About the tenth or twelfth week the metacarpal bone of the thumb presents an exception to this rule, by having its ossific centre in the carpal extremity. The epiphyses show themselves about the second or third year ; and about the twentieth the metacarpal row is com- pleted. THE PHALANGES, (Fig. 220.) The phalanges compose the bones of the thumb and fin- gers, and have each a shaft and two extremities. The thumb has two bones; each of the fingers three, placed in rows. The first row or phalanx is next to the metacar- pal bones. The bones of this row have their base concave for receiving the head of the corresponding metacarpal bone, and, on either side, a small tubercle for the lateral ligament. The lower extremity presents two small heads, or a pulley-like formation, for articulating with the second phalanx ; the sides form ridges for the thecal attachments. The dorsal surface is convex and smooth, the palmar concave. The second phalanx is smaller than the first; its superior extremity presents two small cavities for the two heads of the first phalanx ; the lower extremity is slightly concave for articulation with the third phalanx. The third or last phalanx is the smallest of the three, and is remarkable for having its lower extremity flat, thin, and semicircular, and its palmar surface rough. The first phalanx of the thumb is stronger and shorter than those of the fingers, while its second or last phalanx is broader. T02 LIGAMENTS OF THE SHOULDER. Development. — The phalanges are developed from two centres — one for the base and one for the shaft. Ossifica- tion begins about the same time as in the metacarpal bones, and is observed first in the third phalanx, then in the first, and last of all in the second phalanx. During the third and fourth years the epiphyses of the first row are seen ; during the fourth and fifth those of the second row ; and during the sixth and seventh year those of the last row. All the phalanges are completed by the twentieth year. SECTION V. LIGAMENTS OF THE SUPERIOR EXTREMITY. The ligaments to be considered are those of the shoulder, arm, forearm, and hand. LIGAMENTS OF THE SHOULDER. The bones of the shoulder being composed of the clavicle and scapula, we have clavicular and scapular ligaments ; and the clavicle being connected with the sternum, ribs, and scapulae, we have hence a division of the ligaments into sterno-clavicular, costo-clavicular, and scapulo-cla- vicular. Sterno-clavicular articulation, (Fig. 141.) — This articula- tion has a capsular ligament, an inter-articular cartilage, an inter-clavicular ligament, and two synovial membranes. The capsular ligament is a strong, fibrous, membrane surrounding the joint, and covered by the origin of the sterno-cleido-mastoideus at its anterior portion. This cap- sule has its fibres thickened in front and behind — -hence the names of the anterior and posterior sterno-clavicular ligaments. The anterior, called also the radiated ligament, proceeds from the anterior extremity of the clavicle downward and inward to the articular margin of the cavity of the sternum. The posterior is not so distinct, but pursues a course behind the joint similar to the anterior. The inter-articular cartilage is seen on opening the joint. It is circular in shape, and completely separates the ster- LIGAMENTS OF THE SHOULDER. num and clavicle. Below it is thin, where it is attached to the sternum ; above it is thick, where it is connected to the clavicle. Its centre is thin and sometimes perforated. Its structure is fibro-cartilaginous, and its use seems to be to adapt the bony surfaces to one another as well as to bind them together. The synovial membranes are two in number, one on each side of the inter-articular cartilage. They are found to contain but little synovia, and are strongly attached to the adjacent surfaces. Cos to-clavicular articulation, (Fig. 141.) — This articula- tion has a short bundle of parallel ligamentous fibres, called the rhomboid or inferior ligament, running obliquely downward and forward from the inferior surface of the sternal end of the clavicle, to be inserted into the upper surface of the cartilage of the first rib. Posteriorly it is in contact with the subclavian vein, and anteriorly with the subclavian muscle. The inter-clavicular ligament is placed at the superior end of the sternum, and extends from the posterior sternal extremity of one clavicle to that of the other. Scapulo-clavicular articulation, (Fig. 221.) — This articu- lation has a capsular ligament at the junction of the acromion process and clavicle, whose fibres being thick- ened above and below, and passing from one bone to the other, receive the name of superior and inferior ligaments. A synovial membrane, somewhat indistinct, is seen upon the articular surface of this joint, and occasionaly an inter-articular cartilage is found. The coraco-clavicular ligament is double, and consists of the conoid and the trapezoid. The conoid is the smaller and posterior of the two ; its base is above and attached to the tubercle on the inferior surface of the acromial end of the clavicle. The trapezoid is more anterior and external; it is broader, longer and thinner than the conoid, and is attached above to an oblique line on the under surface of the clavicle at the tubercle, and below. to the root of the coracoid process. 704 LIGAMENTS OF THE ARM. Between these two ligaments fatty and cellular structures are seen, and occasionally a small bursa. FlG 221 The ligamentumbicorne, called also the clavicular fascia, springs from the root of the coracoid process and divides, whence it receives the name of the bifid ligament. One of the divisions goes to the first rib, the other spreads over the suhclavius I ^ muscle as a fascia, and extends as far forward as the rhomboid ligament. The ligaments of the scapula are the coracoid and the triangular. (Fig. 221.) The coracoid is posterior, and is stretched across the notch in the superior costa of the scapula, converting it into a foramen. The triangular is anterior, and is also called deltoid or coraco-acromial. It has a broad origin from the superior margin of the coracoid process. Its fibres, which are thin and partially separated, converge, become thicker, and are inserted into the acromion process where it joins the clavi- cle. This ligament forms an arch over the shoulder joint, and is covered by the deltoid muscle. LIGAMENTS OF THE ARM. The Jiumero-scapular articulation contains the following ligaments : — 1st, The capsular ligament (Fig. 221) ; 2d; The coraco-humeral ; 3d, The glenoid. The capsular ligament completely surrounds this joint, being attached above to the margin of the glenoid cavity, and below to the neck of the humerus. Above and below it is dense internally, and externally it is thin. It is loose and has connected with it the tendons of the four capsular FIG. 221 represents the Ligaments of the Shoulder Joint. 1 Superior acro- mio clavicular ligament. 2 Coraco-clavicular ligament. 3 Coraco-acromial ligament. 4 Coracoid ligament. 5 Capsular ligament. 6 Coraco-humeral, or ligamentum adscititium. 7 Tendon of the long head of the biceps muscle. LIGAMENTS OF THE FOREARM. 705 muscles, which almost completely surround it, except a small portion below and internally, where it is conse- quently weaker, and where dislocations of this joint are found most commonly to occur. The coraco-liumeral, accessory ligament, or ligamentum adscititium extends beneath the triangular ligament down- ward and outward to the greater tuberosity, where it is lost in the capsular. This ligament serves to keep the head of the humerus in the glenoid cavity. The glenoid ligament surrounds the margin, and deepens the glenoid cavity ; its free edge is thin, but where it con- nects with the bone it is thick. The tendon of the biceps partly contributes to this ligament. The synovial membrane lines the capsular ligament and glenoid surface, is reflected over the head of the humerus, lines the bicipital groove, and forms a sheath around the tendon of the biceps. LIGAMENTS OF THE FOREARM. The ligaments of the forearm are found in the humero- cubital articulation, or the elbow joint, and are, 1st, The capsular ligament ; 2d, External lateral or brachio-radial ; 3d, Internal lateral or brachio-ulnar ; 4th, Coronary liga- ment ; 5th, Ligamentum teres. The capsular ligament surrounds the elbow joint, and is connected above to the lower end of the humerus, above the articular surface, and below to the articular margin of the ulna and neck of the radius. The external lateral ligament extends from the external condyle above to the annular ligament surrounding the neck of the radius below. The internal lateral ligament extends from the internal condyle, expands and divides as it descends, one portion going to the coronoid process, the other to the olecranon. Between the lateral ligaments in front and behind the joint, the capsular ligament is thin, its fibres insulated, some taking an oblique, others a straight course, and re- ceiving the name of accessory ligaments. 45 706 LIGAMENTS OF THE HAND. The coronary or annular ligament surrounds about two- thirds of the neck of the radius,, and is seen by opening A FIG. 222. B the joint. It extends from the lesser sigmoid cavity of the ulna at its anterior margin, round the radius to the posterior margin of the same cavity. The lig amentum teres or oblique ligament is a round, short, fibrous cord, extending from the root of the coronoid process to the radius below its tubercle. The synovial membrane is com- mon to the three bones composing the humero-cubital articulation, as well as the two sigmoid cavi- ties and neck of the radius. The interosseous ligament occu- pies the space between the radius and ulna, being attached ,to the corresponding edges of those bones, and perforated at its upper and lower ex- tremities. LIGAMENTS OF THE HAND. The ligaments of the hand include those of the carpus 3 metacarpus, and phalanges. LIGAMENTS OF THE CARPUS OR WRIST JOINT. The ligaments of the carpus, or wrist-joint, include the cap- sular ligament, external lateral or radio-carpal, internal late- ral or ulna-carpal, triangular ligament, and annular ligament. The capsular ligament is connected above to the articular FIG. 222, A represents an outer view of the Elbow Joint. 1 The humerus. 2 Ulna. 3 Radius. 4 External lateral ligament. 5 Coronary ligament. 6 Point of attachment of the coronary ligament. 7 8 Accessory ligaments. 9 Interosseous ligament. FIG. 222, B represents an inner view of the Elbow Joint. ] Capsular Liga- ment. 2 Internal lateral ligament. 3 Coronary ligament. 4 Ligamentum teres. 5 Interosseous ligament. 6 Internal condyle. LIGAMENTS OF THE HAND. TOT FIG. 223. margin of the lower ends of the radius and ulna, and be- low to the margin of the three carpal bones of the first row, the scaphoides, lunare, and cunei- forme, fibres being traced also to the bones of the second row. This liga- ment is loose and thin, presenting spaces at different points at which the synovial membrane appears. The external lateral ligament extends from the styloid process of the radius to the scaphoides, and on even to the trapezium and annular ligament. The internal lateral ligament extends from the styloid process of the ulna to the cuneiform bone, and is long and round. Between the lateral, anterior and posterior ligaments are spoken of, which are simply a thickening of the capsular on the front and back por- tions of the joint. The triangular ligament is fibro-cartilaginous, and is con- nected with the styloid process of the ulna and the carpal end of the radius, separating the ulna from the cuneiform bone. It is sometimes perforated, and seems to be a continu- ation of the cartilage on the lower extremity of the radius. The annular ligament is a strong fibrous membrane, attached externally to the scaphoid and trapezium, and internally to the cuneiform, unciform and pisiform bones. It gives the arched form at the wrist, and keeps the flexor tendons in their proper places, and on the back of the FIG. 223 represents the Ligaments of the Wrist Joint. 1 Interosseous liga- ment. 2 Radio-ulnar. 3 Capsular ligament. 4 External lateral. 5 Internal lateral ligament. 6 Capsular ligament of the carpal bones. 7 Os-pisiforme. 8 Ligaments joining the metacarpal with the second row of the carpus. 9 Capsular ligament of the carpo-metacarpal joint of the thumb. 10 Capsular ligament of the metacarpo-phalangeal joint of the thumb. 11 External lateral ligament of the same joint. 12 Capsular ligament of the metacarpo phalan- geal joint of the index finger. 13 13 Lateral ligaments of similar articulations. 14 Inferior palmar ligaments. 15 Capsular and lateral ligaments of the last joint of the thumb. 708 LIGAMENTS OF THE METACARPUS. wrist it is called ligamentum carpi dorsale, and extends from the styloid edge of the radius to the styloid edge of the ulna. The lower head of the ulna is received into the sigmoid cavity of the radius, constituting the lower radio-ulnar articulation, and is retained there by a loose synovial mem- brane termed the sacciform ligament. The synovial membrane covers the articular surface of the bones and the inter-articular fibro-cartilage, and is reflected upon the inner surface of the capsular ligament. The first and second rows of the carpal bones, except the pisiforme, are united by a capsular ligament, extending from one row to the other, and seeming to be a continua- tion of the radio-carpal ; it is also thickened laterally by external and internal lateral ligaments, the former extending from the scaphoides to the trapezium, the latter from the cuneiform to the unciform. The pisiform bone articulates with the cuneiform by a separate cartilage, synovial membrane and proper capsular ligament. Interosseous ligaments are found connecting also the several carpal bones, and ligamentous fibres, run- ning transversely, called from their position palmar and dorsal ligaments. The synovial membrane extends from the first carpal row to the second and down to the metacarpal bones ; it also dips down between the bones of the carpus and lines the inner surface of the capsular ligament, and is thus common to all the carpal and metacarpal articulations, except the cuneiform and pisiforme, the trapezium and metacarpal bone of the thumb, and the space between the third and fourth metacarpal bones, all of which have distinct synovial membranes. LIGAMENTS OF THE METACARPUS, (Fig. 223.) These belong to the carpo-metacarpal articulation, and include the dorsal and the palmar ligaments. The dorsal pass directly from the carpal to the base of the metacarpal bones, the latter being also connected by transverse fibres. MUSCLES OP THE SHOULDER. 709 The palmar pursue a similar course with the dorsal, but are not so strong. The metacarpal bones have also strong lateral connec- tions by transverse ligaments where their surfaces come in contact. The synovial membrane is a prolongation from that of the carpus. The phalangeal extremity of the metacarpal bones form the metacarpo-phalangeal articulation, and include : 1. An- terior ligaments, or capsular ; 2. Lateral ligaments. The anterior ligaments are flat fibro-cartilaginous bands, which run transversely and connect the sides of the heads of the metacarpal bones. The lateral ligaments are thickenings of the capsular laterally, and extend from the sides of the metacarpal bones, and descend as strong, short cords to be attached to the sides of the upper ends of the first phalanges. A synovial membrane belongs to this articulation. LIGAMENTS OF THE PHALANGES OR FINGERS, (Fig. 223.) Each finger has one anterior ligament and two lateral ligaments. The anterior ligament corresponds precisely to the meta- carpo-phalangeal, just described ; and the lateral go from phalanx to phalanx on each side. There is also the usual synovial membrane. CHAPTEK II. ACTIVE ORGANS OF THE SUPERIOR EXTREMITIES. SECTION I. MUSCLES OF THE SUPERIOR EXTREMITY. THESE muscles are arranged into those of the shoulder, arm, forearm, and hand. MUSCLES OF THE SHOULDER. These comprise the deltoid, supra-spinatus , infra-spinor tus, teres-minor, teres-major, and sub-scapularis. 710 MUSCLES OP THE SHOULDER. Deltoid — A, delta, *t8oj, likeness, (Figs. 150,167.) — Dissec- tion.— Make the first incision along the posterior third of the clavicle, the acromial margin, and spine of the scapula; the second from the acromion process, along the middle of the humerus, and commence the dissection from this last incision, turning off the integuments internally and exter- nally with the cellular structure, when this muscle will he exposed. It arises from the external third of the clavicle, fleshy; from the outer margin of the acromion process, ten- dinous and fleshy ; and from the whole of the inferior edge of the spine of the scapula. It is inserted on the outer side of the humerus,near its centre, in a triangular rough surface. This muscle is triangular in shape, thick and strong, cov- ers the shoulder-joint, and gives it its rotundity. The fibres converge — the anterior descending obliquely backward, the posterior forward, and the middle directly downward, the three presenting so many separate parts or muscles. Function. — To raise the arm. and, according to the direc- tion of the fibres, to draw it either forward or backward. Beneath the superior portion of this muscle, extending under the acromion process, is seen a large bursa. Supra-spinatus — supra, above ; spina, the spine — (Fig. 150.) By turning down the deltoid this muscle is seen ; it arises fleshy from the whole of the supra-spinal fossa, also from a strong fascia covering it ; it then passes under the acromion process, ending in a strong tendon, which is firmly attached to the capsular ligament, and is inserted into the inner face of the greater tuberosity of the humerus. Function. — To raise the arm and turn it outward ; also to strengthen the capsular ligament, and to draw it from "between the humerus and glenoid cavity, in the elevation of the arm. Infra spinatus — infra, beneath ; spina, spine — (Fig. 150,) arises from the whole of the dorsum of the scapula below its spine, from the margins of the bone, and from the aponeurosis covering it, forming a flat, triangular muscle. Its fibres converge, the superior going horizontally, the inferior ascending obliquely forward, to a strong central MUSCLES OF THE SHOULDEK. 711 tendon, which goes under the acromion process, adheres to the capsular ligament, and is inserted into the middle face of the greater tuherosity of the humerus. Function. — To roll the os-humeri outward and backward. To strengthen the capsular ligament and to draw it out of the joint, in the outward movements of the arm. There is also a hursa between the tendon of this muscle and the scapula- Teres minor — teres, round — (Fig. 150,) is a small and narrow muscle, and arises from the inferior costa of the scapula at the lower margin of the infra spinatus, is in- separably attached to, and in fact forms part of this latter muscle. It extends from the cervix to about an inch of the inferior angle, and adhering to the capsular ligament, is inserted tendinous and fleshy into the outer face of the great tuberosity of the humerus. Function. — To rotate the arm outward, and draw it downward and backward. The teres major (Fig. 224) is a flat muscle, and arises from the inferior angle of the scapula upon its rough flat surface. Forming a thick fleshy belly, it ascends forward and outward, and terminates on the inner side of the arm in a broad thin tendon, which is inserted along with the tendon of the latissimus dorsi into the inner or posterior edge of the bicipital groove. The tendon of the teres FIG. 224. major is posterior, and extends lower down the arm than the latissimus. Function. — To roll the arm in- ward, and draw it backward and downward. The sub-scapularis (sub, under; scapula, shoulder-blade) is a broad triangular muscle, which arises from the whole of the venter, and the superior and inferior costse of the scapula. Its fibres converge to the neck of the scapula, pass below the coracoid process, adhere to the inferior part of the capsular ligament, and terminate in a strong tendon, FIG. 224 represents the Muscles of the Shoulder. 1 Deltoid 2 Subscapu- laris. 3 Teres major. 4 Triceps. 712 MUSCLES OF THE ARM. which is inserted into the lesser tuberosity of the humerus. Between the tendon of this muscle and the neck of the scapula, a large bursa communicating with the joint is seen ; also another smaller one between the tendon and capsular ligament. Function. — To roll the arm inward and downward. MUSCLES OF THE ARM, (Fig. 225.) These comprise the biceps flexor cubiti, cwaco-bradiialis , brachialis anticus, tri- ceps extensor cubiti, and anconeus. Biceps flexor cubiti. — Dissection. — Make an incision along the middle an- terior region of the humerus down to the elbow-joint, which cross by a trans- verse incision at the middle of the arm, turn aside the integuments and fascia, 11 and this muscle will be exposed. It is superficial and forms the swell along the front part of the arm. It arises by two heads ; the internal or short head comes from the coracoid process in com- mon with the coraco-brachialis ; the ex- ternal or long head arises by a round tendon from the upper part of the gle- noid cavity of the scapula, goes through the joint, over the head of the humerus, surrounded by, but external to, the sy- novial membrane, and then descends through the groove between the tuberos- ities of the humerus, between the tendons FIG. 225 represents the Muscles on the front of the Arm. 1 Clavicle. 2 Coracoid process. 3 Acromion process. 4 Head of the humerus. 5 Ten- don of the biceps. 6 Ligamentum adscititium. 7 Insertion of pectoralis major. 8 Long head of the biceps. 9 Insertion of the deltoid. 10 Insertion of pec- toralis minor. 11 Coraco brachialis. 12 Short head of biceps. 13 Latissi- mus dorsi. 14 Triceps. 15 Body of the biceps. 16 External part of triceps. 17 Brachialis anticus. 18 Origin of the flexor muscles. 19 Insertion of bra- chialis an ticus. 20 Tendon of the biceps. 21 Bicipital aponeurosis. 22 Flexor carpi radialis. 23 Palmaris longus. 24 Supinator radii longus. MUSCLES OF THE ARM. 713 of the latissimus dorsi and teres major behind, and the pec- toralis major in front. Becoming fleshy it unites with the belly of the short head, at first loosely by cellular tissue, but a little below the middle of the arm the two heads become inseparably united to form a thick fleshy belly, which a little above the elbow-joint ends in a flat tendon, passing in front of the joint to be inserted into the posterior part of the tubercle of the radius. A bursa is placed between the tendon and the tubercle, and from the ulnar side of the tendon proceeds the bicipital aponeurosis, which, passing over the brachial artery and nerve, joins the general fascia of the forearm. Function. — To flex the forearm. This muscle is related with the brachial artery, which see. Coraco-brachialis , (Fig. 225.) — Arises from the coracoid process, in common with the short head of the biceps, ten- dinous and fleshy. It descends, connected with the short head about three or four inches, along the inner arm to be inserted tendinous and fleshy into the inner side of the humerus, about its centre, and by an aponeurosis into the ridge leading to the internal condyle. Function. — To raise the arm and draw it forward ; it can also turn it outward. The musculo-cutaneous nerve pene- trates this muscle. It is related with the brachial artery, which see. The brachialis anticus or internus (Fig. 225) arises on either side of the insertion of the deltoid by two fleshy slips, which uniting descend, occupying the whole front of the lower part of the humerus, to be inserted into the coro- noid process of the ulna by a strong tendon. This tendon is between the supinator radii longus and pronator radii teres, and passes beneath the tendon of the biceps and over the elbow-joint. Function. — To bend the forearm and strengthen the elbow-joint. This muscle also, as the biceps, has a relation with the brachial artery, which see. Triceps extensor cubiti — *?"* *«$o3uu$, three heads — (Fig 226.) — This is a three-headed muscle, large and powerful, 714 MUSCLES OF THE FOREARM. FIG. 226. and covering the whole hack part of the humerus. It arises hy its long head from the lower margin of the cervix scaptila3 by a flat, short tendon. The second head comes from the outer and hack part of the humerus, just below the greater tu- berosity. The third head) called brachialis externus, but more pro- perly internus, arises fleshy from the inner side of the humerus, near the insertion of the teres major. The three heads unite to form one muscle, which adheres strongly to the bone, and, ending in a broad tendon, is inserted into the posterior part of the olecranon process. A bursa is seen between the tendon and olecranon. Function. — To ex- tend the forearm. The Anconeus — ayxcov, the elbow, (Fig. 230,) arises tendinous from the external condyle of the os-humeri. It is concealed partly by the triceps, and appears to be a portion of this muscle. It is inserted into the ridge of the upper extremity of the ulna connected with the olecranon. function. — To extend the forearm. MUSCLES OF THE FOREARM. These comprise two divisions : 1st, Flexors and Prona- tors on the anterior forearm ; 2d, Supinators and Extensors on the posterior. The first division includes eight muscles, the pronator radii teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris, flexor digitorum sublimis perforatus , flexor digitorum pro/undus perforans, flexor longus polticis, pronator quad- ratus. FIG. 226 represents the Triceps Muscle, a External head of the triceps. 6 Its long head, c Its short head, d Olecranon process, e Radius. / Capsular ligament. MUSCLES OF THE FOREARM. 715 Pronator radii teres, (Fig. 227-)— Dissection.— Make an incision through the integuments along the centre of the forearm, from the elbow to the wrist ; FIG. 227. make a second incision transversely about the middle ; turn off the integuments to the fascia, which latter dissect off sepa- rately, and this muscle will be exposed. It arises fleshy from the internal con- dyle, and tendinous from the coronoid process of the ulna ; its course is obliquely across the forearm to be inserted mostly tendinous into the middle of the back part of the radius. .Function. — To pronate the hand by rolling the radius inward. The flexor carpi radialis (Fig. 22*7) arises tendinous from the inner condyle, and fleshy from the upper part of the ulna, the interrhuscular ligaments, and brachial fascia, forming a thick fleshy belly upon the ulnar side of the last mus- cle, and descends obliquely outward be- neath the anterior annular ligament, through a groove in the os-trapezium, to be inserted into the fore part of the base of the metacarpal bone of the index finger. A bursa is seen between the tendon and os-trapezium. Function. — To flex the hand on the wrist. This muscle is related with the radial artery, which see. The palmaris longus (Fig. 227) arises from the inner condyle by a slender tendon, and fleshy from the inter- muscular ligaments. Forming a short belly, it ends in a long slender tendon, which is inserted into the anterior annular ligament and palmar aponeurosis. FIG. 227 represents the Superficial Muscles on the front of the Forearm. 1 Inferior portion of the Biceps. 2 Brachialis anticus. 3 Triceps. 4 Pro- nator radii teres. 5 Flexor carpi radialis. 6 Palmaris Longus. 7 Flexor sublimis perforatus. 8 Flexor carpi ulnaris. 9 Fascia palmaris. 10 Pal- maris-brevis muscle. 11 Abductor-pollicis manus. 12 Flexor-brevis pollicis raanus. 13 Supinator radii Longus. 14 Extensor-ossis metacarpi pollicis. Y16 MUSCLES OF THE FOREARM. Function. — To flex the hand and make tense the palmar aponeurosis. This muscle is sometimes absent. The flexor carpi ulnaris (Fig. 22*7) arises from the inner condyle tendinous, from the inner side of the olecra- non process fleshy and tendinous, from the ridge upon the inner side of the ulna nearly its whole length, and from the fascia of the forearm. It forms a round tendon which is inserted into the pisiform bone, and base of the metacar- pal bone of the little finger. Function. — To flex the hand, and bring it towards the ulna. A bursa is seen between the tendon and os pisiforme* It is related with the ulnar artery, which see. Flexor digitorum sublimis perforatus, (Fig. 227.) Dis- section.— Kemove the superficial muscles, and the flexor sublimis is brought to view. It arises from the inner condyle and coronoid process, tendinous and fleshy — fleshy from the tubercle of the radius and for three or four inches below the tubercle. Before the muscle reaches the wrist it divides into four tendons which pass to the palm of the hand beneath the anterior annular ligament, and then diverge to be inserted into the second phalanx of each finger. The tendons of this muscle are enclosed in a strong sheath, and at their intersection split into two, through which the tendon of the perforans passes. Function. — To bend the second phalanges on the first. A large bursa surrounds the tendons of this muscle beneath the annular ligament. The flexor digitorum profundus perforans (Fig. 228) arises beneath the sublimis, from the upper anterior sur- face of the ulna and inner portion of the interosseous liga- ment, fleshy — also fleshy from the coronoid process of the ulna and inner side of the olecranon process. A thick muscle is formed, which at the lower part of the arm divides into four flat tendons, which go beneath the annular ligament, enter the ligamentous sheaths on the fingers, pass through the slits in the perforatus, and are inserted into the last phalanx of each finger. Function. — To bend the last phalanges, and with the sublimis the hand. MUSCLES OF THE FOREARM. UT The flexor longus pollicis (Fig. 228) arises, fleshy, be- neath the flexor sublimis from the front part of the ra- dius, below its tubercle, for about two-thirds of its extent, and from the radial portion of the inter- FIG. 228. osseous ligament. It also has a ten- dinous origin from the inner condyle. Its tendon passes beneath the annular ligament, and between the two heads of the short flexor and sesamoid bones, to be inserted into the second phalanx of the thumb. A bursa is seen in connection with the tendon of this muscle. Function. — To bend the last phalanx of the thumb. The pronator quadratus (Fig. 228) arises from the anterior front surface of the lower extremity of the ulna, broad, tendinous and fleshy, passes transversely, and is inserted into the lower front sur- face of the radius. It is a small, square muscle, concealed by the flexor longus pollicis and flexor profundus. Function. — To pronate the hand by rolling the radius inward. The muscles on the posterior part of the forearm include the supinators and extensors, and com- prise ten muscles, viz : the supinator radii longus, exten- sor carpi radialis longior, extensor carpi radialis brevior, extensor carpi ulnaris, extensor digitorum communis, supi- nator radii brevis, extensor ossis metacarpi pollicis manus, extensor minor pollicis, extensor major pollicis, indicator. Supinator radii longus. — Dissection. — Make an incision along the middle of the back part of the arm and forearm. Make a second incision transversely about the middle of FIG. 228 represents the deep muscles on the front of the Forearm, a Internal lateral ligament, b Capsular ligament, c Coronary ligament, d Flexor pro- fundus perforans. t Flexor longus pollicis. /Pronator quadratus. g Adductor pollicis manus. /i Lumbricales. i Interossei. MUSCLES OF THE FOREARM. the forearm, turn aside the integuments and this muscle will be exposed. It arises tendinous and fleshy from the ridge leading to the external condyle, commencing a little below the inser- tion of the deltoid, also from the inter-muscular ligaments- FIG. 229. A thick muscle is formed, which de- scends along the outer part of the elbow, and at the middle of the fore-arm termi- nates in a flat tendon, which is inserted upon the styloid side of the radius. Function. — To supinate or turn the palm of the hand upward by rolling the radius outward. Extensor carpi radialis longior (Fig. 229) arises from the external ridge of the os humeri, between the external con- dyle and supinator longus, tendinous and fleshy. A thick, short belly is formed^ which about the middle of the radius ends in a flat tendon, which passes under the posterior annular ligament and over the wrist, to be inserted into the poste- rior part of the root of the metacarpal bone of the fore-finger. A bursa is seen surrounding the tendon of this muscle under the annular ligament, and another at its insertion. Function. — To extend the wrist and hand. Extensor carpi radialis brevior (Fig. 229) arises from the external condyle and external lateral ligament, tendi- nous and fleshy. A thick fleshy belly is formed, situated FIG. 229 represents the muscles on the back of the forearm, a Inferior portion of the biceps, b Inferior portion of the brachialis anticus. c Inferior portion of the triceps, d Supinator radii longus. e Extensor carpi radialis longior. /Extensor carpi radialis brevior. g Tendinous insertions of these two latter muscles, h Extensor communis digitorum. i Auricularis, a portion of extensor communis. j Extensor carpi ulnaris. fcAnconeus. / Flexor carpi ulnaris. m Extensor minor pollicis. n Extensor major pollicis. o Posterior annular ligament. MUSCLES Of THE FOREARM. T19 beneath the last muscle, which about the middle of the forearm ends in a flat tendon, which passes under the pos- terior annular ligament, in the same groove with the last muscle, and is inserted into the root of the metacarpal bone of the second or middle finger, on its back part. Function. — To extend the wrist and hand. The extensor digitorum communis (Fig. 229) arises from the external condyle, intermuscular ligament, and fascia, tendinous and fleshy. It descends to about the middle of the forearm, where it ends in four tendons which pass in a common groove of the radius under the posterior annular ligament, and on the back of the hand diverge to the roots of the fingers, where they are connected by cross slips, from whence they expand over the whole posterior part of all the- phalanges of the fingers. The portion of this muscle going to the little finger receives .the name of auricularis. A bursa is connected1 with the tendons of this muscle under the posterior annular ligament, and can be traced along these tendons to the base of the first phalanges. Function. — To extend all the fingers. The extensor carpi ulnaris (Fig. 229) arises tendinous from the external condyle, and fleshy from the intermus- cular ligament and fascia; also fleshy from the back part of the ulna. It then descends, crossing obliquely the upper part of the radius and ulna, to end in a strong tendon, which passes through a groove on the back of the ulna, to be inserted into the base of the metacarpal bone of the little finger. A bursa is seen where the tendon passes through the groove of the ulna. Function. — To extend the wrist and hand. The supinator radii brevis (Fig. 230) arises tendinous and fleshy from the external condyle, external lateral and coronary ligaments, and from a ridge on the outer and upper part of the ulna. On removing the superficial mus- cles attached to the external condyle, it is seen surrounding the outer and upper part of the radius, and inserted into the tubercle of the radius, and into the oblique ridge lead- ing to the insertion of the pronator teres.- Function. — To roll the radius outward. 720 MUSCLES OF THE FOREARM. Extensor ossis metacarpi pollicis manus, (Fig. 230.) — This muscle, called also extensor primi pollicis, arises fleshy from the posterior part of the ulna, just below the anconeus from the interosseous ligament, and from the posterior part FIG. 230. of the radius, below the supinator brevis. It ends in a round tendon which goes over the radial extensors, and through a groove on the styloid side of the radius, to be inserted into the os-trapezium and into the base of the metacarpal bone of the thumb. A bursa is seen where the tendon passes through the groove of the radius. Function. — To extend the meta- carpal bone of the thumb. The extensor minor, or secundi pollicis, (Fig. 230,) arises, tendinous and fleshy, from the posterior part of the ulna, below its middle, and from the interosseous ligament and radius. It descends and passes through the same groove of the radius with the last muscle, and is in- serted into the posterior part of the first phalanx of the thumb. Function. — To extend the first phalanx of the thumb. The extensor major, or tertii pollicis, (Fig. 230,) arises, above the middle of the ulna on its posterior part, from the interosseous liga- ment, and from the back of the radius. It ends in a tendon which passes through a separate groove of the radius, and goes to be inserted into the last phalanx of the thumb. A synovial membrane supplies its tendon at the wrist. Function. — To extend the last phalanx of the thumb. The indicator (Fig. 230) arises tendinous and fleshy from FIG. 230 represents the Deep Muscles on the back of the Forearm, a Inferior portion of the humerus. 6Olecranon process, c Body of the ulna, d Anco- neus. e Supinator radii brevis. / Extensor ossis metacarpi pollicis. g Exten- sor minor pollicia. h Extensor major pollicis. i Indicator, j First dorsal interossei. MUSCLES OF THE HAND. the middle of the back part of the ulna. It is a small muscle, concealed by the extensor ulnaris and communis. It ends in a tendon which passes along the same groove with the extensor communis, beneath the annular ligament, and is inserted with the tendon of that muscle into the back part of the second and third phalanges of the fore finger. Function. — To extend the fore finger.* MUSCLES OF THE HAND. Dissection. — Make an incision from the wrist along the middle of the palm to the base of the fingers ; make a second incision crossing the first transversely about its centre, now reflect the integuments to either side, which will lead to the * During the dissections in the winter of 1849-50, in the Baltimore Col- lege of Dental Surgery, a muscle was seen in connection with the indicator which seems to be entirely new, or at least not present in the dissections of anatomical writers, as we cannot find that they make any mention of it. We have thought the name of Extensor Jlccessorius Jndicis not inappropriate. We will quote the explanation given of this muscle, from the April number, 1850, of the Medical Examiner. " It had its origin on the right hand by a delicate» tendinous membrane, from the radio-carpal articulation, behind the posterior annular ligament, and in the same groove with, and posterior to the tendons of the extensor communis and indicator, forming a fleshy bulb nearly the size of the plantaris of the leg. It soon, however, divided into two bellies— the one short and attached or inserted by a delicate tendon, into the tendon of the in- dicator, near the base of the metacarpal bone of the fore finger — the other larger, and con- nected also to the indicator, but near the articulation of the metacarpal bone with the first phalanx of the fore finger, and also by a narrow tendon, as seen in the drawing. On the left hand the muscle had but one belly, which ended in a tendon having a similar at- tachment and resemblance to the larger belly upon the right. Its function seems evidently to assist the indicator in the extension of the fore finger. Fig. 231 exhibits the muscle as seen from the dissection. " a a Posterior annular ligament laid open. 6 Origin of the new muscle . c Its smaller belly. 260. ankle, and is distributed upon the upper external part of the foot ; the latter supplies the heel and external ankle. Muscular branches are given off to the various muscles in its course. The nutritious artery enters the nu- tritious foramen of the tibia. The plantar arteries form the ter- minating branches, and are two in number. The external, the larger of the plan- tar branches, passes outward and for- ward above the flexor brevis to the fifth metatarsal bone; from this it curves inward, across the foot, to the first metatarsal bone, forming the ar- cus plantarisj and ends by anastomo- sing with the anterior tibial. In its course the external plantar gives off the perforating branches, four in number, from its arch, which perforate as well as supply the inter- osseous muscles. The digital arteries come also from the plantar arch, and after sending branches to the lumbricales and interossei, divide so as to supply the adjacent sides of contiguous toes. The artery of the little toe runs along its outer surface. The internal plantar passes along the inner side of the FIG. 260 represents the Arteries on the Sole of the Foot, o Posterior tibial artery. 6 Branches to the heel, c Branch of the posterior peroneal artery. d Point of division into external and internal plantar arteries, e External plantar. /Point where the external plantar begins to form its arch, g Anas- tomosis of anterior tibial with the plantar arch, h i j Muscular branches of external plantar, k Anastomosis of external plantar with the metatarsal artery. I m Digital branches to the little toe. n Digital branches to the other toes, o o Distribution of latter upon the toes, p Internal plantar artery, q Its anas- tomosis with the plantar arch, r s t Muscular branches of internal plantar. u Digital branch to the big toe. v Sub articular branch. * Anastomosis in the pulp of the toe. 778 VEINS OF THE INFERIOR EXTREMITY. sole of the foot, supplying the muscles of the great toe, and anastomosing with the digital arteries. VEINS OF THE INFERIOR EXTREMITY. FIG. 261. The veins of the lower extremity, like those of the upper, are divided into the superficial and deep. The superficial veins are situated immediately beneath the skin, and consist of the internal and external sapliena. The internal sapliena begins on the inner and upper part of the foot, ascends in front of the internal malleolus, along the inner portion of the leg to the inner condyle, behind which it passes ; from this it still ascends along the inner and anterior part of the thigh to within two inches of Pou- part's ligament, where it penetrates the fascia lata to join the femoral vein. In this course it receives numerous cutaneous veins, and at its termination is joined by the pudic, superficial epigastric, and su- perficial circumflex veins. The external sapliena begins at the outer ankle and dor sum of the foot, ascends on the back of the leg to the ham, where it joins the popliteal vein. The deep veins accompanying the arte- ries have the same names, and are two for each artery, called venae comites; hence we have anterior, posterior tibial and peroneal veins, uniting to form the popliteal, which is superficial to the artery. After traversing the popliteal space to the opening in the tendon of the adductor magnus, it changes its name to femoral. From this point the femoral, which is here on FIG. 261 represents the Saphena Major Vein, a Superficial epigastric vein, ft Internal pudic vein, c Superficial circumflex vein, d Orfgin of saphena major, e Its termination in the femoral vein. NERVES OF THE INFERIOR EXTREMITY. the outside of the artery, gets behind it as it ascends-, and at the upper part of the thigh is on the inner side. Having reached Poupart's ligament, it again changes its name, and becomes the external iliac vein, which will be found described along with the veins of the trunk. The popliteal receives, besides the external saphena, the articular veins of the knee joint. The femoral, besides the internal saphenus, receives the muscular veins and veins of the profunda. SECTION IV. NERVES OF THE INFERIOR EXTREMITY. The source of nervous supply to the lower extremity comes from the lumbar and sacral plexuses. These plexuses (see Fig. 204) form two large nerves, the anterior crural, and great sciatic, the origin of which, together with the plexuses, are all described under the head of nerves of the chest and abdomen. The branches from the lumbar plexus which supply the upper part of the thigh, as the nmsculo- cutaneous, genito crural, obturator, and anterior crural, have also been described. BRANCHES OF THE ANTERIOR CRURAL NERVE. The cutaneous branches, four or five in number, pierce the fascia lata, and from their direction upon the skin, have been called the middle, external, internal and anterior cuta- neous nerves. These principally supply the integuments on the anterior and inner part of the thigh, some descend- ing as low as the knee. Muscular Brandies. — These are numerous to the various muscles on the front, inner and outer portions of the upper part of the thigh. The arterial branch penetrates the sheath of the femoral vessels, and sends twigs which surround them. The internal saphenus penetrates the sheath and accom- panies the femoral artery to the opening in the adductor magnus. It here leaves the artery, and getting to the inner side of the knee, between the tendons of the sartorius and gracilis, joins the internal saphena vein, which it attends. NERVES OF THE INFERIOR EXTREMITY. to the inner side of the foot, supplying in its course the integuments of the leg. The internal saphenus communi- cates with the obturator, and the following branches are FIG. 262. named as proceeding from it : A fe- moral cutaneous to the integuments of the inner and outer thigh ; a tibial cutaneous going off a little above the inner condyle, and descending to sup- ply the inner leg as low as the ankle; an articular branch to the knee joint, and an anterior cutaneous, given off near the inner condyle, to supply the parts about the patella. BRANCHES OF THE SACRAL PLEXUS GOING TO THE THIGH, (Fig. 263.) The lesser sciatic or ischiatic nerve comes out of the pelvis, below the pyriforniis, in company with the ischi- atic artery, and is divided into mus- cular and cutaneous branches. The muscular are called the inferior gluteal nerves, and go chiefly to the lower part of the gluteus maximus, some of the filaments being traced to the inner thigh and perineum. Of the cutaneous brandies, some go to the perineum and are called perineal cutaneous. A branch,, called posterior cutaneous, is traced over the tuberosity of the ischium, and at the lower portion of the gluteus maximus, comes through the fascia and descends along the posterior and middle part of the thigh, and the popliteal space, as low down as the middle of the calf of the leg. In this course it gives FIG. 262 represents the anterior Crural Nerve and its branches, a Point where the anterior crural emerges from beneath Poupart's ligament, b Di- vision of the nerve into its branches, c Femoral artery, d Femoral vein. « Branches of obturator nerve. /Saphena nerve. NERVES OF THE INFERIOR EXTREMITY. 781 off many cutaneous branches to the posterior and lateral parts of the thigh, as well as a communicating branch in the ham, to the external saplienus nerve. The gluteal nerve comes out of the pel- pIG. g63. vis, through the great sciatic foramen, along with the gluteal artery, and divides into a superior branch, which ascends to supply the gluteus medius and minimus muscles ; and an inferior branch, which descends to supply, besides the glutei, the tensor vaginas femoris. The internal pudic and. obturator nerves are described in another place. The great sciatic or posterior crural nerve (Fig. 263) is the principal trunk from the sacral plexus, and the largest nerve of the body ; it comes out of the pelvis through the larger sciatic foramen, below the pyriform muscle, sometimes through it ; descends on the back of the thigh, about midway between the tuber- osity of the ischium and trochanter major, over the small rotators, to about half way down the thigh, where it divides* into the popliteal and peroneal. This division some- times occurs as high as the pelvis at the plexus. Above it is concealed by the glu- teus maximus, below by the hamstring muscles. The sciatic nerve gives off fila- ments to the hip joint, the various mus- cles in its course, and the integuments. The popliteal nerve may be considered the continued trunk FIG. 263 represents the Sacral Plexus and its branches, a Lumbo sacral nerve. 6 Gluteal nerve, c Anterior branches of the four upper sacral nerves. d Sacral plexus, e Internal pudic nerve. / Lesser sciatic nerve, g Great sciatic nerve, h External popliteal nerve, i Internal popliteal nerve, j Its brandies to the calf of the leg. k Posterior tibial nerve. I Plantar nerves, m Anterior tibial nerve, n Musculo cutaneous nerve, o Its cutaneous portion. p External saphenus nerve. *T82 NERVES OF THE INFERIOR EXTREMITY. of the great sciatic. It accompanies the popliteal artery between the heads of the gastrocnemius, to the lower border of the popliteus muscle, where it becomes the posterior tibial nerve. BRANCHES OF THE POPLITEAL NERVE, (Fig. 263.) External sapJienus or communicans tibice comes off above the knee and descends the back part of the leg, beneath the fascia, to 'about halfway between the knee and foot, where it emerges and becomes cutaneous, unites with a branch from the peroneal nerve, and is then traced in company with the external saphenus vein on the outer border of the tendo-Achillis to the back part of the external malleolus. It is distributed by numerous filaments to the integuments of the heel, sole, and outer margin of the foot and little toe, communicating likewise with the dorsal nerves of the foot. Muscular branches are sent off to the gastrocnemius, soleus, plantaris and popliteus muscles. Articular branches come off and go to the joint. POSTERIOR TIBIAL NERVE, (Fig. 263.) The posterior tibial nerve is a continuation of the popliteal, and accompanies the posterior tibial artery to the back part of the inner ankle, where it divides into the internal and external plantar nerves. The posterior tibial sends off in its course a few muscular branches, and a few cutaneous plantar branches. The internal plantar, (Fig. 264,) larger than the external, goes along the inner side of the tarsus, giving filaments to the plantar muscles and integuments, and at the base of the great toe it divides into four digital branches, the first running along the tibia!" side of the great toe, and the other three subdividing so as to supply the opposing sides of all the rest except the little toe. The external plantar nerve accompanies the external plan- tar artery to the fifth metatarsal bone, where it divides into two digital branches, one of which goes along the NERVES OF THE INFERIOR EXTREMITY. 783 outer side of the little toe, and the other divides so as to supply the opposing sides of the little and the fourth toe. The external plantar supplies the various muscles in its course, as well as the integuments on the outer margin and sole of the foot. PERONEAL NERVE, (Fig 263.) This nerve is the external popliteal, or second division of the great sciatic. It descends, along with the tendon of the biceps, to the head of the fibula, FIG. 264. where it divides into the anterior tibial and external peroneal branches. Be- fore this division it sends off two long branches, called the external and in- ternal peroneo-cutaneous nerve, the former being distributed to the in- teguments along the fibula, the latter descending on the gastrocnemius, and about the middle of the leg uniting with the external saphenus or com- municans tibiae. The anterior tibial nerve (Fig. 259) descends in front of the interosseous ligament, along with the anterior tibial vessels, to the ankle, where it passes under the annular ligament, and is distributed to the muscles and integuments on the dorsum of the foot and the two first toes ; it supplies the various muscles in its course. The external peroneal or musculo-cutaneous nerve (Fig. 259) descends the leg between the peroneus longus and extensor longus digitorum, and about the middle of the FIG. 264 represents the Plantar Nerves. 1 Posterior tibial. 2 Abductor pollicis. 3 Flexor brevis digitorum. 4 4 Section of tendons of this latter muscle. 5 5 Abductor minimi digiti. 6 Musculus accessorius. 7 External plantar artery. 8 Internal plantar artery. 9 9 External plantar artery in the deep portion of the foot. 11 Point where external plantar artery gets to the dorsum of the foot. 12 Flexor longus pollicis. 13 Posterior tibial nerve. 14 Internal plantar nerve. 15 External plantar nerve. 16 Digital nerves. 784 SUMMARY OF MUSCLES. leg it penetrates the fascia, and goes to the outer malleolus, where it divides into external and internal branches — the former supplying the integuments on the three outer toes, and connecting with the external saphenus ; the latter being distributed on the two first toes, and communicating with the internal saphenus. SUMMARY OF THE MUSCLES OF THE INFERIOR EXTREMITY. MUSCLES OF THE THIGH. ON THE FRONT. Tensor vaginae femoris. Sartorius. Rectus. Vastus internus. Vastus externus. Crureus. ON THE BACK. Biceps. Semitendinosus. Semimembranosus. INNER MUSCLES. Iliacus internus. Psoas magnus. Pectineus. Adductor longus. Adductor brevis. Adductor magnus. Gracilis. MUSCLES OF THE LEG. ON THE FRONT. Tibialis anticus. Extensor longus digitorum. Extensor longus pollicis. Peroneus tertius. ON THE OUTER LEG. Peroneus longus. Feroneus brevis. ON THE BACK. Gastrocnemius. Plantaris. Popliteus. Flexor longus pollicis. Flexor longus digitorum. Tibialis posticus. ON THE DORSUM. Extensor brevis digitorum. Interossei dorsales. MUSCLES OF THE FOOT. Musculus accessorius. ON THE SOLE. Abductor pollicis. Flexor brevis digitorum. Abductor minimi digiti. Lumbricales. Flexor brevis pollicis. Adductor pollicis. Flexor brevis minimi digiti. Transervalis pedis. Interossei plantares. ' RELATIONS OF THE MOUTH WITH THE EXTREMITIES. 785 The muscles of the hip, which are most generally found among those of the lower extremities, will he found in the summary of the muscles of the trunk. ANATOMICAL AND PHYSIOLOGICAL RELATIONS OF THE MOUTH WITH THE EXTREMITIES. Under this head we shall only refer to the well known pathological fact of trismus or locked-jaw resulting from injury to the toes, thus establishing a relation between the mouth and inferior extremities. This relation, in all prob- ability, occurs through the spinal marrow and fifth pair of nerves. The relations of the mouth with the superior extremities are, no doubt, equally close and important with those of the inferior extremities. THE END. 50 INDEX, A. Abdollaliph, an anatomist, PAGE 35 Abdomen, . . , *• '; , .; 537 Abdominal spinal nerves, . . 634 Abdomino-crural nerves, . 634 Abducentes nerve, . . . 353 Abducentes-oculi nerve, , . 423 Abduc tor indicis, . . . 723 Minimi digiti, . . . 723 Minimi digiti pedis, . 767 Oculi' . .350 Pollicis, . . . .722 Pollicis pedis,' ... 766 Aberrations of light, . . .348 Absorbents of the trunk, . 590 Absorption of the skin, » . 130 Accelerator urinae, . . , 679 Accessory ligament, . . . 705 Acervulus, .... 414 Acetabulum, .... 474 Acini of Malpighi, ... 639 Acini of the liver, . . .582 Active organs of the head, . 222 Of inferior extremity, . . 757 Of mastication, . . 294 Of the superior extremity, . 709 Of the trunk, . . 481, 537 Adamantine organ, . . . 253 Adductor minimi digiti, . . 723 Brevis, 760 Longua 760 Magnus, .... 760 Oculi, .... 350 Pollicis, . . . 723, 768 Adipo-glandular fascia, . . 546 Adipose tissue, . . . .79 Quality of, ... 79 ^Ethmoid cells, Anterior, . . 382 Posterior, . 382 ^Ethmoidal notch, . . . 179 Air cells, . . . .; 610 Alae-minores, . • ^ . . 192 Alar-cartilages of nose, . . 380 Ligaments, . . . 755 Albicantia, .... 412 Albinus, (a distinguished anato- mist,) 38 Albumen, 52 Chemical analysis of, . 52 Alcmaeon, (father of anatomy,) 33 Alveolar arch, . , . .199 Processes, . . 199 Alveolar artery, . ;. ' •. Alveoli, .... Alveolo-dental periosteum, Amnion, Amphiarthrosis, . Amygdaloid lobe, . 436 162 . 324 671 . 352 405 AnaTfascia, . 676 Anastomotica magna, . 774, 730 Anastomosis, . . . .90 Anatomy — antiquity of, . History of, . . . . ! First cultivator of, . • Science of, . . * .33 Its divisions, . . < • I 58 Comparative, . • • 58 Human, . .. - ,- .. 59 Pathological, >. »; . 59 Special 59 Surgical, . . . .59 Anatomical Schools of Athens and Alexandria, . ., * . 34 Anconeus muscle, . . . 714 Andral, . . . .,. . 39 Anfractuosities of brain, • 409 Angle of the pubis, . . . 474 Angles of occipital bone, . 184 Of parietal bone, . . .181 Angular motion of joints,. . 153 Angularis artery, * ... 431 Animal matters destitute of nitro- gen, . .... 56 Annular ligament of radius, . 706 Ligament of wrist-joint, . 707 Ligaments, . . . 725 Anterior, . . . 725 Posterior, ... 725 Anterior atlanto-axoid ligament, 460 Anterior auris, . . 362 Cerebral artery, . . 425 Cervical plexus, . 511 Circumflex artery, . . 728 Clinoid processes, . 193 Communicating artery, . . 425 Costo-sternal ligaments, . 467 Transverse ligament, . 466 Crucial ligament, . . 753 Crural nerve, . . 635, 779 Dental canal, ... 264 Nerve, . . . .264 Inferior spinous process, . 472 Interosseii, .... 724 Jugular vein, . . . 509 Interosseous artery, . . 733 788 INDEX. Anterior ligament of head of ribs, 466 Of ankle joint, . . 755 Of metacarpus, . . 709 Mental foramen, . . 209 Occipito-atloid ligament, . 457 Palatine canal, ... 201 Plantar ligaments, . . . 757 Ligaments of phalanges, . 709 . Pubic ligament, . . .478 Pulmonary plexus, . 500, 612 Sacral foramina, . . .451 Sacro-iliac ligament, . . 476 Sacro-sciatic ligament, . . 476 Spinal arteries, . 427, 506 Superior-spinous process, . 472 Temporal artery, . . 432 Nerves 268 Tibial nerve, . ;viv . 783 Artery 775 Vein, . .-/-.-. 778 Antcro-lateral columns of spinal marrow, . . . 490 Anti helix, . . . . .361 Antitragicus 363 Antitragus, 361 Ant-eater— teeth of, . . 283 Antrum Highmorianum, . 191, 201 Aorta, 626 Abdominal, . . 96, 627 Arch of, ... 96, 626 Branches of, . . . 97, 98 Origin of, . . .96 Thoracic, . . .96, 626 Aortic plexus, . . .632 Apes — diciduoui teeth of, . . 275 Aponeurosis palmaris, . . 726 Plantaris, . . . .771 Apophysis, . . « . 165 Apparatus, . . . . . 41 Ligamentosus-colli, . . 459 Appendages of the eye, . . 349 Of skin, . . . 124,132 Of mucous membrane, . . 141 Appendices epiploicae, . . 572 Appendix vermiformis, . . 572 Aqua-labyrinthi, . . . 374 Aqueduct of the cochlea, . 187,373 Of Fallopius, . 187, 188, 371 Of Sylvius, . . . .414 Of vestibule, ... 188 Aqueous humur 342 Arachnoid canal, . . . 419 Arachnoidea tunica, . . . 388 Arbor vitae 406 Arch of the aorta", - ... 96 Arches of the palate, . . 307 Arch of the pubis, . . . 474 Arciform fibres, . . . 401 Arcus profundus artery, . 731, 734 Areolar tissue, ... 75 Armadillo, Teeth of, . . . 283 Arm-bone, ...» 692 Arteria centralis, . . . 339 Choroidea, ... 426 Corporis cavernosi, . . 660 Dorsalis penis, . . 660 Helicinse, .... 660 Princeps-cervicis, . . 504 Pollicis, . . . .776 Innominata, . . 96, 627 Arteries. Contractility of, . . 92 Coronary, ... 96 Elasticity of, ... 92 Arteries of the forearm, . . 731 Of the oesophagus, . . 497 Sheath of, ... 93 Structure of, . . .91 Artery of the bulb, . . 660, 680 Carotid 96 Of the carpus callosum, . 425 External iliac, . . .98 Internal iliac, ... 98 Femoral, . . . .99 Subclavian, ... 97 Arthrodia, 152 Articular cavities, . . . 166 Ligaments, .... 151 Articulata, .... 47 Articulation of atlas 'with axis, . 459 Of atlas with occiput, . 457 Of axis with occiput, . . 458 Of frontal bone, . . 180 Of lower jaw, . . .213 Of oblique processes, . 457 Of ossa pubis, . . . 477 Of palate bone, . . 205 Of superior maxillary bone, . 203 Arytenoid cartilages, . . 526 Glands, .... 533 Arytenoideus obliquus, . . 531 Trans* versus, . . . 531 Aryteno-epiglottideus, . . 531 Ascending cava, .... 629 Cervical artery, . . .*•:. 506 Colon 573 Pharyngeal artery, . . 431 Asclepiades, . . . .35 Aselius, 38 Asternal ribs, . . . .463 Astragalus, . . • 748 Atlas, 447 Attachment of muscles, . . 144 Attollens aurem, . . . 362 Auditory ganglia, . . . 402 Auricularis magnus nerve, . .511 Muscle, .... 719 Auricular nerve, . . 267, 329 Automatic systenij 116 Nerve, 515 Aves, 289 Axillary artery, .... 727 Plexus, .... 736 INDEX. 789 Axillary vein, Axis, Azygos uvulae, 736 448 309 B. Baboons, 276 Badger, Teeth of, . . . 282 Barry, Dr 103 Bartholine, Thos. . Basement membrane, . . . 136 Base of the skull, ... 218 Basilar artery, .... 427 Basilar process of occipital bone, 183 Basilic vein, .... 735 Bear, Teeth of, . . . . 282 Biceps flexor cubiti, . •. 712 Biceps flexor cruris, . *». . 761 Bichat, . . . .... :. r 38 Bicipital groove, ».-.-: . .-., , , -,.- . 692 Bicuspid teeth, . .t. -:« 232 Bidlow Gothofridus, ... 38 Bifid ligament, ... 704 Bile, 55 Birds, 48 Bladder, (urinary) . . .643 Blood-vessels of, . . 649 Function of, . . . . 649 Ligaments of, . . . 644 Nerves of, . . . . 649 Regions of, . ..«.•,. 646 Structure of, >. . . 646 Blood, 39,66 Agents preventing coagulation, 69 Agents promoting coagulation, 69 Automatic motion of, . . 74 Chemical analysis of, . 71 Color of, . . . .68 Crassamentum of, . . 67 Force of, . . . .70 Formation of, . . . 74 Form of blood-globules, . 71 Liquor-sanguinis of, . 67 Microscopic examination of, 71 Quantity of, ... 68 Rapidity of, . . . '. . 70 Serum of, . . , ^t* 67 Size of blood-globules, . 72 Smell of, . ... 68 Taste of, . . . .68 Viscidity of, . . . 70 Vital properties of, . . 73 Blood-vessels of abdomen, . 548 Of the ear, .... 376 Of the eyebrows, . . 355 Of the eyelids, . . .358 Of expression, ... 330 Of the head, . . . .428 Of inferior extremity, . 772 Of mastication, . . . 298 Of the nose, . . . 383 Blood-vessels of palate, . . 309 Of papillae, ... 311 Of pharynx 317 Of prehension, . . . 226 Of salivary glands, . . 302 Of spinal marrow, . . 392 Of superior extremity, . . 726 Of the teeth, ... 259 Of the trunk, . '. . .683 Bone, Cellular, ... 164 Cancellated 164 Chemical analysis of, . 162 Compact, .... 164 Composition of, . . 161 Ethmoid, . . . .189 Frontal, . . , . 177 Inferior maxillary, . . 209 Inferior turbinated, . . 207 Membranes of, . .169 Occipital, ... 182 Sphenoid, . . . .192 Strength of, . . . 164 Structure of, ... 212 Superior maxillary, . 196 Tuberosity of, ... 198 Vomer, . . . . 208 Bones of the cranium, . . . 177 Density of, . . . 163 Of the face, . . . .196 Of extremities, . . 163 Flat 162 Of the foot, ... 748 Of the forearm, . . .694 Of the leg, ... 745 Growth of, . . . . 173 Of the head, ... 163 Lachrymal 206 Long, .... 162 Malar, 205 Nasal, .... 207 Number of, . . . .162 Palate, .... 203 Parietal, . . . .180 Short, .... 162 Of the shoulder, . . . 689 Situation of, . . . 163 Surface of 165 Temporal, ... 184 Of the trunk, . . 163, 443 Unguiform, .... 206 Borelli's estimate of heart's force, 103 Brachial plexus, . . 513, 736 Artery, .... 729 Nerve, 739 Brachialis anticus, . . . 713 Internus, . . . .713 Brachio radial ligament, . 705 Ulnar ligament, . . . 705 Brain, .... 110,392 Sinuses of, . . . . 396 Branches of axillary artery, . 728 790 INDEX. Branches of brachial artery . 729 39 Of radial artery, . 731 732 Carpo metacarpal articulation , . 708 . 697 Broad ligaments, . 557, 666 . 525 Bengarius Jacobus, Structure of, . . 36 699 Bronchial arteries, . Glands, 611, 627 . 595 611 Caruncula lachrymalis, Myrtiformis, Casein, .... . 357 . 664 . 53 . 609 Chemical analysis of, 53 Buccal artery, • • . Glands, . . Nerve, . Teeth, Buccinator, Bulb of the urethra, . •*•;"'* iv c. Calamus scriptorius, . Calcaneo cuboid ligament, Scaphoid ligament, Calcigerous tubes, . * Callus, formation of, . Calyces of kidneys, Calycyform papilla, . Camper's fascia, Ligament, . ." -:» Canal of Bichat, - . • .:'.'•• Of Fontana, . ; • .: i Of Petit, . . 434 . 323 268 . 232 225 . 658 . 407 756 . 756 168 . 173 641 . 311 546 . 676 . 419 . 335 344 Cartilage cells, Chemical analysis of, Form of, . Functions of, . Structure of, Cartilages of the larynx, ' Of the ribs, Cartilaginous stage of bone, System, relations of, Tissue, . . • ;: ' Casserian ganglion, Cat, teeth of, . ••> • Cava Inferior, .+'••>••'&- '••< •*•<• Superior, . <•>» ' Cavernous sinus, Cavity of reserve of a tooth, Cell, nucleated, . Of Schwann, -.';<;•• Cellular tissue, . Continuity of, . • :3jtf*i . 157 157 . 156 . 153 . 157 525 . 465 . 170 . 159 156 . 423 . 281 . 100 101 . 398 . 251 . 63 39 . 75 77 . 76 Posterior palatine, Canals of bone, Cancellated bone, Canine fossa • • . 204 167 . 164 197 Division of, . Quantity of, Relations of, . • • * 77 . 77 78 . 164 Canine teeth . • 230 35 Capillaries, structure of, 85 . 271 Capillary tissue, . Capsulae renales, . - . >• Blood-vessels of, . . Function of, . . Nerves of, . v 'l>r'**' Structure of, . 84 641 . 642 642 . 642 642 Chemical analysis of, Cementum, Central cartilage of nose, Centrum ovale majus, Minus, . 271 . 24a 380 . 420 420 . 730 Capsular ligament of atlas, . Of carpus, . • *.-*• e? Of elbow joint, . Of head of rib, '.- ' -'i> . 460 706 . 705 . 466 Cerebellum, Cerebral surface of cranium, Cerebro spinal axis, V»" Cerin, . • • * «' » '* '•'• '• 108, 405 . 223 386 . 57 Of hip joint, 751 408 Of humerus, Of lower jaw, . Of metacarpus, Of wrist joint, . . 3 Capsule of Glisson, . Of the lens, . ,i «£? Caput gallinaginis, . *-•'»••** Cardiac nerves, Plexus, . 704 . 214 . 709 706 . 579 . 344 . 659 500 . 501 Ceruminous glands, Cervical nerve, . • -V- Plexus, ;,,-,.-* .."*> Vertebra?, : . - "•'•• Fascia, Glands, Cervicalis anterior artery, . Ascendens, Descendens, . . 364 330 . 511 446 . 522 . 523 . 507 . 493 . 493 Carnivora, Carotid arteries, . Artery internal, Canal . 273, 280 96, 627 425 . 187 Posterior artery, Cervico facial nerve, * *•- . Cetacea, teeth of, . Cetyl, . ... 507 . 329 289 . 57 External and internal, . 428 Cheiroptera, ... . . 279 INDEX. Chemical relations of skin, Cheiromys, . . • Cheselden, .... Chest, . . (*>,:(. v General remarks on, . Cavity of, Diameters of, Form of in Foetus, . Chiasma of optic nerves, Chimpanzee, . Deciduous teeth of, Chondrin, Chemical analysis of, . Chorda tympani nerve, Tendineae, . . . Vocales, », ^f* an Chorion, 9i ; * .., •«, ... • Of tongue, vK* ?;.;:•*-•, i. Choroid artery, ., . - .,;.* Coat of the eye, Chyle, . .. .;.;i*.-J. . ; nPl Chyme, . .. n ,..v, , Ciliae, . . . .-..-,,i.«t Of epithelium, . Ciliaris muscle, . . Ciliary arteries, long, ,. Short, .... Ganglion, r -*»^ Ligament, Process, . • .*. ••,!•.» Cineritious matter, Circle of Willis, . ^ Circular sinus of Ridley, Circulation, development of, Foetal, . . ...... ,,v>h General, . Lymphatic, . Portal, Pulmonary, . Venous, . Circumduction of joints, Circumflexa illii artery, . Circumflexus palati, ,: ,j Circumflex arteries, nerve, .... Clavicle, . . '*". ;1 Function of, . : ' « Structure of, . Clefts or fissures of bone, . Cleft-palate, . Clitoris Coccygeus muscle, . Coccygeal ganglion, Coccyx, .... Development of, . Cochlea, Cochlear nerve, . . Coecum, .... Collar bone, Colon, .... Columbus, .... . 131 278 . 38 460 . 468 468 . 469 469 . 421 . 273 . 274 55, 158 . 55 266, 329 . 619 . 528 . 671 . 378 . 426 . 334 . 39 39, 564 . 356 136 . 326 346 . 346 346, 516 . 335 . 336 . 109 427 . 398 104 . 105 89 . 105 87 . 101 99 . 153 . 548 . 308 728 . 739 691 . 692 . 692 . 167 307 160, 662 679 . 515 . 453 . 454 371 . 375 572 . 691 . 573 . 371 Columnae carneae, . . . 619 Columna of nose, . . . 381 Columnar bladder, . . . 648 Epithelium, ... 136 Commissura mollis, . . . 416 Commissure of cerebellum, . 403 Common carotid arteries, . . 259 Communicans noni nerve, . 512 Tibial nerve, . . .782 Compact bone, . . . 164 Comparative anatomy of the teeth, 268 Complexus muscle, . . 494 Compound fibrous membranes, . 155 Compressor nasi, . . . 325 Penis, .... 678 Urethra, .... 680 Conarium, . . . . . 414 Concha, 362 Condyles, 165 Of the humerus, . . 693 Of femur, . . . .744 Of occipital bone, . . 183 Conical papilla?, . . . .311 Consistence of muscles, . . 143 Constrictor isthmii faucium, . 309 Pharyngis inferior, . . 316 Medius, . . . .316 Superior, . . . 316 Contractility, . . . .65 Of arteries, ... 92 Conoid ligament, . . . 703 Conus vasculosus, . . . 652 Converging fibres of cerebrum, . 410 Convolutions of the brain, . 409 Functions of, . . .411 Coraco acromial ligament, . 704 Brachialis, .... 713 Clavicular ligament, . 703 humeral ligament, . . 705 Coracoid apophysis, . . 166 Ligament, .... 704 Cordae Willisii, ... 396 Cord spinal, . . . .112 Cordiform tendon of diaphragm, 552 Cornea, 340 Elastica, .... 342 Structure of, ... 341 Corniculum laryngis, . . 527 Cornu ammonis, . . . .417 Corona ciliaris, . . . 336 Glandis, . . . .658 Coronary arteries, . . 96, 624, 627 i Artery, . . . .553 Ligament, . . 577, 706 Veins 624 Coronoid process of ulna, . 696 Corpora Albicantia, . . . 413 Cavernosa, . . 160, 657 Mammillaria, . . .412 Malpighi, ... 639 Olivaria, . . . 115, 401 7-92 INDEX. Corpora pyramidalia, . Restiformia, Striata, Corpus callosum, Dentatum, Denticulatum, Fimbriatum, . Geniculatum externum, Geniculatum internum, Highmorianum, . Corpus Luteum, Pampiniforme, Psalloides, Spongiosum, Corpuscle, Corpuscles of Purkinji. Corpusculum arantii, Corrugator supercillii, Cortex of the hair, . Costae, .... Costo clavicular articulation, Xiphoid ligaments, Cotyloid cavity, Ligament, Course of muscles, Cowper's glands, Cranium, bones of, . Its diameters Crassamentum, Cremasteric artery, Cricoid cartilage, Crico arytenoid ligaments, . Arytenoideus posticus, Arytenoideus lateralis, Thyroideus, Crista of the pubis, . Crucial ridge, . Crura cerebri, . . . Cruraeus, : Crural nerve, Crustacea, . Crusta petrosa, . Crystalline lens, Chemical analysis of, . Structure of, Cubital fascia, Cubitalis manus profunda, Cuboides, .... Cuneiform bones of foot, Bones of hand, Process of occipital bone, Cupola of ear, Cuspidati, .... Cutaneous sphincter ani, Branches of crural nerve, System, . Tissue, Cuticle, . . . Cutis vera, Cutis vera of tongue, Cystic duct, 115, 401 115, 401 108, 416 . 419 407 . 417 417, 671 . 415 415 . 651 678 . 654 . 418 . 658 72 . 168 620 . 325 . 132 . 463 703 . 468 166, 474 . 752 143 . 660 177 . 196 71 . 654 . 526 . 528 , 530 . 530 . 529 . 473 183 . 411 759 . 635 293 . 243 343 . 343 , 344 . 725 733 . 749 750 698 . 183 372 . 230 574 . 779 134 . 123 127 . 325 378 . 585 D. Dartos, 650 Deep cervical fascia, . . 522 Deep perineal fascia, . . . 676 Deltoid fascia, ... 725 Deltoid ligament, . . 704, 756 Deltoid muscle, .... 710 Dens sapientiae, . . . 233 Dental arches, . . . 255 Dental canals, . . . .198 Dental groove, primary, . . 249 secondary, . 251 Dental pulp, .... 234 Dentata, 448 Denticulata ligamenta, . . 389 Dentine, 238 Blood-vessels of, . . 240 Formation of, . . • 241, 242 Structure of, . . . 239 Dentition in mammalia, . . 272 Dependency in organization, . 44 Depressor anguli oris, . . 224 Labii inferioris, . . 225 Labii superioris alaeque nasi, 224 Oculi, . ... 350 Descendens noni-nerve, . .511 Descending colon, . . . 573 Development of bone, . . 170 Of circulation, . . 104 Of frontal bone, . . .180 Of lachrymal bones, . 207 Of muscular system, . . 146 Of nasal bones, . . 207 Of palate bones, . . .205 Of parietal bones, . . 182 Of superior maxillary bone, . 203 OfVomer, ... 208 Diameters of cranium, . . 196 Diaphragm, .... 551 Blood-vessels of, . . . 553 Nerves of, ... 554 Diarthrosis, .... 152 Diembroeck, .... 38 Digastric lobe, . • , • . . 405 Muscle, . -..- •-. . 304 Nerve 329 Digital arteries, . . 733, 777 Digital fossa3, . . . ]79 Nerves 740 Dilator nasi muscle, . . 326 Direction of muscles, . . .143 Discharges of mucous membrane, 141 Displacements of mucous memb. 141 Dissection, Art of, . . . 33 Dissection, General rules of, . 40 Diverging fibres of cerebrum, 410 Dog, Teeth of, . . . .281 Dorsal is carpi artery, . . 731 Ulnaris, . . . .733 Lingua artery, . . 430 INDEX, 793 Dorsalis carpi nerve, . . . 740 Dorsal ligaments of hand, . 708 Foot, . . 756 Vertebrae, 449 Dorsum of ilium, . . . 471 Duct of Steno, . . 226, 3UO Wharton, . . .301 Thoracic, ... 122 Ductus arteriosus, . . . 620 Communis choledochus, 566, 581 Ejaculatorius, . . 653, 655 Venosus, . . .89, 581 Duodenum, . . . , 565 Blood-vessels of, . . .568 Function of, . . . 568 Nerves of, . . . . 568 Dura mater of brain, . . 393 Blood-vessels of, . . . 394 Nerves of, ... 395 Reflections of, . . 395 E. Ear, 360 External, ... 361 Blood-vessels of, . .364, 376 Nerves of, . . 364 375 Edentata, Teeth of, . . . 283 Eighth pair of nerves, . . 424 Ejaculator-seminis, . . . 679 Elasticity of arteries, . . 92 Elasticity of yellow fibre, . . 149 Elements of human organization, 50 Chemical, . . . .50 Extractive, ... 54 Organic, . * ,,:.. . 52 Elephant, Teeth of, . . 283 Emulgent artery, . . 627, 641 Enamel, . . . . 242 Formation of, ... 253 Organ of, .< . . 253 Enarthrosis, . « . . 152 Encephalon, .... 392 Endocardium, .... 622 Ensiform cartilage, „ ,; 462 Ephesius Rufus, . . . .35 Epicranial aponeurosis, . . 325 Epididymis, . . . . 652 Epigastric region, . . . 538 Epiglottic glands, . . .533 Epiglottis, . . ... 527 Epiphysis, . * . ,:. . . 165 Epiploic arteries, . * .. 563 Epithelia, . . . . * . 39 Epithelium, . . vv, • 135 Ciliated, . .,.» ... . 136 Columnar, . » . . .< . 136 Scales of, . .M t;v . 135 Equator Oculi, »;;; - 4 ,. 2, . 338 Erasistratus, . - r* . ., . 34 Erectile tissue, . v ;* 160 Erector clitoridis, . . .680 Penis, . . . 678 Spinae, . . . .492 Erinacidae. .... 279 Eruption of permanent teeth, . 245 Temporary teeth, Ethmoid bone, .... 189 Articulations of, . , . Development of, . -. . 192 Structure of, . . . 191 Cells, 190 Eustachian tube, . 137, 187, 366 Valve, . . .617 Eustachius, . ... * 37 Excito-motory nerves, . . HO Excretion theory of dentine, . 241 Exhalants, .... 86 Exhalation of the skin, . . 385 Expiration, .... 612 Expression, Blood-vessels of, . 330 Nerve of, . . . 327 Organs of, . . . . 324 Extensor brevis digitorum pedis, 769 Accessorius indicis, . 721 Carpi radialis longior, . . 718 Brevior, . 718 Ulnaris, . . .719 Communis digitorum, . 719 Pedis, ., .762 Minor pollicis, ... . * 720 Major pollicis, . . . 720 Ossis metacarpi pollicis, . 720 Proprius pollicis, . . . 763 External carotid artery, 259, 428, 501 Circumflex artery, . . 773 Costo transverse ligament, . 466 Cutaneous nerve, . . 739 Ear, 361 Epigastric artery, . . 548 Iliac artery, .... 98 Vein, ... 779 Ilio-inguinal nerve, . . 635 Jugular vein, . . 262, 507 Lateral lig. of ankle joint, . 756 Elbow joint, 705 Knee joint, . 753 Wrist joint, 707 Malleolus, . . . .747 Maxillary artery, . . 504 Oblique muscle, . . . 539 Peroneal nerve, . 680, 783 Plantar artery, . . . 777 Nerve, . . 782 Pudic artery, . . 548, 773 Respiratory nerve, . . 514 Saphena vein, . . . 778 Saphenus nerve, . . 782 Sphincter ani muscle, . . 574 Eye, form of, . v .. . 331 Situation of, . . . 331 Eyeball, Nerves of, . ,'. . 346 794 INDEX. Eyebrows, Blood-vessels of, Nerves of, Eyelids, Blood-vessels of, Nerves of, . Structure of, . F. 354 355 355 355 358 358 355 Fabricius, 37 Face, bones- of, ... 196 Facial artery, . 226, 428, 430, 504 Nerve, . . 327, 423 Falciform ligament, . . 556, 576 Fallopian tubes, . . . 671 Fallopius Gabriel, . . .37 Aqueduct of, . . . 187 False pelvis 478 Falx major, . V. . 179 Cerebelli, . . . .395 Cerebri, . - - . . v . . 395 Fascia . . ' . . .1^54 Brachialis, . . . 725 Dentata, '. .. . . 417 Femoris, . . . 770. Iliaca, 551 Lata, . .._ . ' . 770 Plantaris, . "« , . .771 Profunda, . ' ' '. , '• . 522 Propria, . , . . 547 Transversalis, . . . 546 Of inferior extremity, . . 769 Of the neck, ... 522 Of leg 771 Superficial of abdomen, 770, 545 Of the pelvis, ... 675 Of the perineum, . . 677 Of the superior extremity, 724 Fasciculi, . . . . HI Fasciculus of muscle, . .144 Fats, . |»: . ••. . . 56 Fauces, .•" .... 307 Femoral artery, . . 772, 99 Nerve, . . . .635 Vein, ... 778 Femur, 742 Fenestra ovalis, . . . 366 Fibre'of animallife, .'. .- .145 Muscle, . 144 Organic life, , ' . 145 Fibres of the pilp, . ' . 238 Fibrin. . . .-'•" .' . 52 Chemical analysis of, . 53 Of muscle, . . . .146 Fibro cartilages, ,' ' , . 455 Cartilaginous bodies, . . 148 Cartilaginous tissue, . 159 Functions of, . . .159 Fibrous capsules, . . . 154 Envelopes, . .148, 154 Fibrous envelope of brain, . 155 Coat 135 System, relations of, . 156 Fibrous tissue, . . . .148 Elasticity of, . • >fc; . 148 Extensibility of, . . .148 Flexibility of, . 148 Tissue, white, . . 149 yellow, . . 149 Fibula, 746 Fifth pair of nerves, . . 422 Fifth ventricle, . . . .419 Filliform papillae, . . .311 First pair of nerves, . . . 420 Fishes, 48 Fishes, Teeth of, ... 292 Fissure, Glasserian, . . 185 Fissure of Sylvius, . . . 193 Flat bones, .... 162 Flexor accessorius, . . . 767 Brevis digitorum pedis, 767 Minimi digiti, 723, 768 Pollicis, . 722, 768 Carpi radialis, . . 715 Ulnaris, . . 716 Communis digitorum pe- dis, . . .765 Longus digitorum pedis, 765 Pollicis, . 717,766 Digitorum profundus per- forans, . . ;" 716 Sublimis perforatus, 716 Floating ribs, .... 463 Flocculus, 405 Foetal circulation, . . . 105 Follicle, Simple 119 Follicle of the hair, Follicles, Gastro-enteric, . . 140 Of mucous membrane, . 137 Fontanelle, Anterior, . '' I"V'*; • 181 Fontanelle, Posterior, ;''••"*. 181 Fontanelles, . . . .222 Foramen auditorium externus, 188 Internus, . 188 Caroticum, . . . 187 Coecum, . . . .179 Commune anterius, . . 416 Posterius, . . 416 Incisivum, . . . 201 Intervertebral, •**'*•.;' . 444 Lacerum medius, . . 194 Posterius, . . . 183, 187 Superius, .; -?v •'-•.'• 194 Magnum, . . " V' . 182 Of Monroe, . .. :- i 418 Opticum 194 Ovale, . . . -V 194, 618 Rotundum, . . . 194, 366 Of Scemering-, . . . 340 Spheno-palatine, . . . 205 OfWinslow, ... 558 • INDEX. 795 Foramina of bone, Orbital, . Of sup. maxillary Of temporal bone Thebesii, . Formative force, Formation of dentine, Enamel, . Hair, . Forms of articulation, . 167 179 bone, 202 . 188 . 618 65 . 241 253 . 133 152 . 417 Gasserian ganglion, . 187, 262 Gastric artery, . . . 563, 627 Favuli, . . . 562 Fluid, .... 138 Glands, ... 562 Serves, . ... . 500 Plexus, ., . r. 631 Gastrocnemius, ..... 764 Gastro-colic omentum, . . 556 Enteric follicles, . . . 140 Hepatic omentum, . . 556 Pulmonary mucous membrane, 134 Gelatine, . . . * 55 Fossae, .... Nasal, . . v . 166 . 218 fc Digital, . . ... . fc Innominata, . Navicularis, Fourth pair of nerves, Ventricle, Fourchette, . Fovea elliptica, Hemispherica, Froenum preputii, . Frena of the lips, Frenum epiglottidis, Linguae, Frontal bone, . Eminence on, Sinus of, . Frontal nerve, Fronto-nasalis muscle, . Function, . » . 179 . 361 662 . 422 . 407 . 662 . 371 . 371 656 . 320 527, 529 . 313 177 . 178 178 . 353 . 325 41 Gemelli muscles, . . . 674 General development of the skull, 221 Genio-hyoideus, .... 305 Genio-hyoglossus, . . . 305 Genito-crural nerve, . . . 635 Urinary mucous membrane, J34 Germinal vesicle, . . . 670 GimbernaTs ligament, . . 541 Ginglimus, 152 Glandular tissue, . . . 117 Glands, Brunner's, . . 138, 567 Buccal, . . .,,'.. 323 Ceruminous, . , . 364 Labial, .... 320 Lumbar, .... 593 Lymphatic, . » . 119 Mammary, . . . .118 Mesenteric, . . .592 Molar 323 Of cartilage, . Of fibrous system, Of mucous membrane, Of the skin, . 158 . 150 140 . 129 111 Palatine, .... 323 Peyer's, ... 138, 570 Odoriferous, . . . 129 Sebaceous, . . , , .129 Structure of, . , J , . 117 Sudoriferous, . . . 128 Solitary, .... 139 Tartar, 322 Of the chest, ... 595 Of the larynx, . . .533 Of mucous membrane, . 137 Of small intestine, . .593 Of stomach, ... 592 Of Tyson, . . . .656 Glandulae Pacchioni, . 394, 396 Odoriferse, . . . .656 Glandular artery, . . . '504 Glans clitoridis, .... 663 Penis, .... 658 Glenoid cavity, . . . 166, 185 Ligament, . . . 705 Gliding motion of joints, . . 153 Glisson's capsule, . . . 579 Globules of the blood, t .,' . 39 Form of, .... 71 Size of, . . * 72 G. Galen, Claudius, . . „ -'„ Galeopithecus, . • . «. Gall-bladder, . Blood-vessels of, . .'«• Lymphatics of, *•- Nerves of, . 35 . 277 584 . 585 585 . 585 107 Lumbar, Restiformia, . . i. Of the spinal nerves, . Ganglion of Arnold, Of Casser, . Of Cerebellum, Of Cloquet, . . • . OfGasser, . 632 402 . 391 518 . 423 407 . 518 187 Of Laumonier, OfMeckel, . OfRibes,. Semilunar, . , , Gangl ionic system, . . ,, Gasserian fissure, 518 264,517 . 516 . 630 116 . 185 Structure of, . . . 72 Globulin, ..... 54 Globus major, * r..t .* " . 653 T96 INDEX. Globus minor, • 653 Hippocrates, .... 34 Glosso-pharyngeal nerve, 314, 424 Hippopotamus, .... 285 Glottis, . . . * ,. : . 528 Hog, teeth of, ... 285 Gluteal nerves, . .>•• .ii •:» ' ' 781 Horizontal fissure of liver, . . 578 Gluteus maximus, 672 Horner, 39 Medius, . . >< 673 Horse, teeth of, . . . . 287 Minimus, 673 57 Humero-scapular articulation, 704 Humerus, 692 39 Development of 694 Goitre, , » 525 Structure of ... 694 Gomphosis, .... 152, 228 Hunters, . ' . . . 38 39 Hyaloid membrane, . . 345 Graafian vesicles, 669 Hyena, teeth of, . . . 282 Gracilis lobe, 405 Hyo-epiglottideus ligament, . 528 Muscle, 759 Hyoid artery, . . . 430, 503 Gramenivora, Teeth of, . 272 Hyoglossus, 1 . . . .306 Granules pigment, 132 Hypochondriac regions, . . 538 Great cerebral commissure, 419 Hypogastric artery, . . .98 Sciatic nerve, . 781 Plexus, . . 632 Greater circulation, . 625 Regions, . . .538 Coronary vein, 6-24 Hypoglossal nerve, . 425, 510 Meningeal artery, 433 Sacro-sciatic ligament, . 476 I. Splanchnic nerve, 630 Grooves of bone, • 166 Iliac regions, .... 539 Guinterius John, . . 36 Iliacus internus, . . . 550 Gums, 321 Ilio-coecal valve, . . . 573 Vascularity of, 321 Ilio-colic valve, ... 573 Gustatory nerve, . . 267, 314 Ilio-hypogastric nerve, . . . 635 Gutters of bones, 167 Ilio-lumbar ligament, . . 475 Scrotal nerve, . . . 635 H. ..-.'•• Ilium, .... 470, 568 . Blood-vessels of, . . . 571 55 Function of, . . 571 Hair follicle, .... 132 Nerves of, . . . .571 132 Impressions on bone, . . 165 Hand, 697 Incisive nerve, .... 267 Harmonia . • 152 Incus, 368 Harvey, 37 Inferior articular artery, . . 775 Haversian canals, 168 Inferior cava, . . . 100, 629 Head, active organs of, . 222 Cerebellar artery, . . 427 Heads of Bones, 1G5 Cervical ganglion, . . 521 Heart 102, 614 Coronary artery, . . 227, 430 Blood-vessels of, . 623 Tosto-sternal ligaments, . 467 Function of, . 624 Dental artery, . . 262, 433 Nerves of, . 624 Nerve, ... 267 Sounds of, ... 625 Gluteal nerves, . . . 781 Structure of, ... 622 Haemorrhoidal artery, g . 680 Hedge-hogs, .... 279 Labial artery, . . 227, 430 f-r i . ° Helix, i 361 Laryngeal artery, . . 503 Hemispheres of brain, . -i1 408 Nerve, . . 500 Hemispherical ganglia, 409 Vein, . . 509 Hepatic artery, . . 579, 627 Longitudinal sinus, . 395, 397 Ducts, . . . ; 581 Maxillary artery, . . 433 Plexus, . JMnwNKPv 631 Bone, . . .209 Veins, . . • . -. 581 Articulation of, 213 Herophili torcular, . - » i" '"' 184 Structure of, . 212 Herophilus, . . ; . . 34 Nerve, . 267, 423 637 Miningeal artery, . . . 431 Hippocampus major, . 41], Minor, . 417 417 Mesenteric artery. . . 627 Inferior mesenteric plexus, . 631 INDEX- Inferior Musculo-cutaneous nerve, 635 Orbital artery, Palatine artery, Palpebral sinus, . Pharyngeal artery, Strait of pelvis, . Thoracic artery, Thyroid artery, . Vein, . Turbinated bones, Articulation of, Development of, . Structure of, . Vermiform process, Inflammation of mucous memb. 434 430 356 431 479 728 506 509 207 208 208 208 405 Infra orbital arteryT~~ . 227, 261 Canal, . . 198 Foramen, . . 198 Orbital nerve, ... 263 Spinatus, .... 710 Infra- spinous fascia, . 725 Trochlear nerve, . . . 354 Infundibuli of kidneys, . . 641 Infundibuliform fascia, . . 547 Infundibulum, . . . . 412 Of the ear, . . . .372 Inguino-cutaneous nerve, . 635 Insectivora, teeth of, . . . 278 Insertion of muscles, . . 144 Inspiration, .... 612 Intercostal arteries, . . 627 Interarticular cartilage, sternum, 702 Lower jaw, 214 Clavicular ligament, . . 703 Intercostales, . . . 599 Intercostal nerves, . . . 633 Costo-humeral nerves, 741, 633 Crural lamina, . . . 412 Lobular fissure, . . 583 Space, . . .583 Maxillary bones, . . 199 Ligament of lower jaw, 215 Pubic ligament, . . . 676 Spinales, .... 496 Spinous ligaments, . . 457 Transverse ligaments, . 457 Intertrochanteric line, •.*».••;? . 744 Vertebral foramen, . . 444 Ligaments, . 455, 466 Intestines, .... 564 Inter transversales, . . . 496 Internal abdominal ring, . 547 Carotid artery, . . 425, 428 Malleolus, ... 746 Costo-transverse ligament, . 466 Cutaneous nerve, . . 738 Epigastric artery, . . 548 Iliac artery, . . . 98 Jugular vein, . . . 508 Lateral lig. of ankle joint, 756 Elbow joint, 705 Internal lateral lig. of knee joint,| 753 of wrist joint, 706 Mammary vein, . . 509 Maxillary artery, 260, 429, 432 Vein," . . 262 Oblique muscle, . . . 542 Occipital protuberance, . 183 Organs of sense, . . . 386 Plantar artery, . . 777 Nerve, . . .782 Pudic artery, ... 660 Nerve, . . .781 Respiratory nerve, . . 512 Saphenus nerve, , . . 779 Saphena vein, . ». . 778 Sphincter ani, . . . 574 Interossei Dorsales, . . 769 Plantares, . . . 769 Interosseous artery, . . 733 Muscles, . . . 724 Nerve, , . 739 Ligament of leg, . . . 755 Iris, 336 Blood-vessels of, . . . 338 Functions of, . . . 337 Nerves of, . .< .*. . 338 Structure of, . . . 337 Irregularities of the teeth, . . 247 Ischiatic nerves, . . 637, 780 Ischio-rectal fascia, . . . 676 Ischium, 472 Island of Reil, . . . .411 Isthmus of the fauces, . . 308 thyroid gland, . 524 Ivory, .... J. Jejunum, Blood-vessels of, Function of, . Nerves of, Joints, angular motion of, Circumduction of, . Gliding motion of, Rotation of, . .* Jolivius, . . s-'>- Jugular eminence, . . K. Kangaroo, Teeth of, . Keratin, Kidneys, Blood-vessels of, Function of, . Lymphatics of, # Nerves of, . ...».<-, L. Labial artery, . . <* Labial glands, • v. . 238 568 571 571 571 153 153 153 153 38 183 282 54 637 641 642 641 64) 504 320 798 INDEX. Labia majora, .... 662 Minora, . . . 662 Labyrinth of the ear, . . . 370 Lining membrane of, . 374 Lachrymal apparatus, . . 358 Bones, ... 206 Articulation of, . 207 Development of, 207 Structure of, . 207 Canals, . 359 Gland, . . .358 Blood-vessels of, 360 Nerves of, . . 360 Lachrymal nerve, . . . 353 Sac, . .<> . . 359 Lacteals, . . . 137, 592 Lactic acid, . . . .56 Lacus, Lachrymalis, . . 355 Lamina cribrosa, . . *. • . 333 Spiralis, . 372 Lateral cartilages of nose, . . 380 Lateralis nasi artery, . . 227 Artery, . . . .431 Lateral ligament of atlas, . 458 Sinuses, .... 397 Ventricles, ... 417 Laxator tympani, . . . 369 Minor, .... 369 Left auricle, . . . .620 Epiploic artery, . , 563 Lateral ligament, . - . 577 Mesocolon, . . . 572 Leiberkuhn, . . . .137 Leidy 39 Lemurs, 276 Teeth of, . . . . 276 Lenticular ganglion, . 346,516 Lesser circulation, . . . 625 Coronary vein, . . . 624 Ischiatic notch, . . 473 Meningeal artery, . . 433 Sacro-sciatic ligament, . 476 Sciatic nerve, . . . 780 Splanchnic nerve, . , 630 Levator ani, .... 679 Anguli oris, . . . 224 Scapulae, . . . 490 Glandulae muscle, . . 524 Labii inferioris, . . 225 Superioris alsequi nasi, 224 Menti, . . . .225 Oculi, .... 349 Palati, . . . .308 Palpebrae superioris,' . 351 Urethra 680 Lewenhoeck, .... 38 Life, Elements of, ... 42 A definite living origin, . 42 Special form, . .43 Definite size, . . 43 Definite structure, . . 43 Life, a nutritive fluid, . ;,: 44 Nutrition, ... 44 y Organic, . . . 116 Ligament, ..... 148 OfWinslow, ... 753 Of Zinn, . . . .350 Ligamenta deuticulata, . . 389 Subflava, . . . .456 Ligaments, .... 150 Of ankle joint, . . .755 Of the arm, . . . . 704 Articular, .... 151 Of bladder, ... 644 Of Camper, . . . .676 Capsular of lower jaw, . 214 Of carpus, . . . .706 Of chest, .... 466 Of foot, . « ' • .756 Of forearm, ... 705 Of hand, . . . .706 Of hip joint, ... 751 Of inferior extremity, . . 751 Of lower jaw, exter. lateral, 214 Internal lateral, . 214 Inter-maxillary, . 215 Of the larynx, . . . 527 Of metacarpus, *.: . 708 Of metatarsus, . . . 757 Mixed, .... 151 Non articular, . . . 151 Of pelvis, ... 475 Of phalanges, . . 709, 757 Of pinna, ... 364 Of shoulder, . . .702 Of spine, .... 454 Of superior extremity, . 702 Of wrist joint, . . 706 Ligamentum adscititium, . . 705 Arcuatum, . . . 553 Bicorne, . . . . 704 Latum pulmonis, . . 604 Mucosum, .... 755 Nuchae, .... 457 Patellae, . . . .753 Teres, . 474, 577, 706, 752 Linea alba, 541 Aspera, .... 743 llio pectinea, . . 471, 478 Semilunaris, . . . 541 Trarisversae, . . 407, 542 Lingual artery, . . 428, 429 Muscle, . . ., ' . 313 Nerve, . 314, 425, 510 Lines on bones, .... 165 Liquor of Coturinius, , • 374 Morgagni, . . . 344 Sanguinis, . . 67 Of Scarpa, . . .374 Liver, 576 Blood-vessels of, . . . 579 Function of, . . . 585 INDEX T99 Liver, lymphatics of, . . . 582 Nerves of, ... 582 Structure of, ... 579 Lobular biliary plexus, . . 583 Venous plexus, . . 583 Lobules of the liver, . . 582 Lobulus anonymus, . . . 578 Caudatus, ... 578 Quartus, .... 578 Spigelii, . . ^ . 578 Locus niger, . • ; ~ »; .412 Long bones, . . , , . 162 Longisimus dorsi, . , * . . 493 Longus colli, . . . 487 Lower jaw, articulation of, . 213 Iriterarticular cartilage of, 214 Stylo-maxillary ligament of, 215 Lumbar arteries, . . . 627 Ganglia, . . . .632 Glands, .... 593 Nerves 634 Plexus, .... 634 Regions, .... 537 Sacral ligament, . . 475 Sacral nerve, . . . 636 Vertebra, . . . 450 Lumbricales, . . •• .'• . 724 Pedis, .... 767 Lunare, ..... 698 Lunula, 133 Lungs, 605 Blood-vessels of, . . 611 Color of, .... 6J7 Density of, . *••! '. . 606 Elasticity of, . * . r\ • .607 Form of, . . . . 606 Function, .... 612 Lymphatics of, . . 612 Nerves of, . . . . 612 Size of, . . . . 606 Specific gravity of, . . 606 Structure of, . . . 608 Surfaces of 607 Lymphatic circulation, . . 105 Glands, . . .119 Of chest, . 595 Neck, . . 523 Trunk, . 591 Vessels, . . .121 Lymphatics of bone, ,-: . 170 Of chest, . . . . 594 Heart, .... 595 Intestines,^ . «•* . 593 Large intestines, . . 593 Liver, .... 593 Pancreas, . . . 594 Spleen 594 Stomach, ... 592 Trunk, ..'..'. *.. . 591 Lyra, 418 M. Macula germinativa, .. . .670 Magendie, . . . • 39 Magna pollicis artery, t^,. .731 Magnum bone, . • ' >» 699 Major helicis, . " * . . 363 Malar bones, .... 205 Articulation of, . . . 206 Development of, . . 26 Structure of, . . 206 Malar nerve, . V .;'. 267,330 Malformation of mucous mem- brane, . . . 141 Malleolus externus, . . . 747 Internus, . . 746 Malleolar arteries, . . . 776 Malleus, . . . . . 368 Malpighius Marcellus, . . 38 Mammae, . . . . 600 Blood-vessels of, . . . 602 Lymphatics of, • . . 602 Structure of, ., . «\ . 602 Mammalia, teeth of . 49, 270 Mammary glands, . . .118 Mammillaria 412 Mammillary eminences, . . 179 Mandrille, .... 276 Marsupialia, .... 282 Massa-carnea Jacob! Sylvii, . 767 Masseter muscle, . . . 294 Nerve, ... 268 Masseteric artery, . . . 434 Mastication, blood-vessels of, 298 Nerves of, . . 298 Mastodon, teeth of, . . 285 Mastoid apophysis, . . . 166 Portion of temporal bone, 186 Maxillary nerve, . . . 330 Sinuses, . . . 201 Meatus auditorius externus, 363, 377 Internus, . 371 Inferior, .... 382 Middle, .... 382 Superior, .... 382 Urinarius, . . . 663 Median cartilage, of the nose, . 380 Basilic vein, . . . 736 Cephalic vein, . . 736 Nerve, .... 739 Vein, 736 Lobe of the cerebellum, . 406 Mediastinal arteries, . . . 627 Mediastinum, .... 604 Anterior, .... 604 Middle, .... 604 Posterior, .... 604 Mediastinum testis, . . 651 Medula oblongata, . . 114, 400 Nerves of, ... 403 800 INDEX. Medulla of the hair, . . .213 Medulary membrane, * . 169 Medula spinalis, . . . .387 Megatheroides, teeth of, . 283 Meibomian glands, . . . 357 Membrana granulosa, . . 670 Pupilaris, . . . 338 Tympani, . 364, 377 Membrane basement, . . . 136 Membranous labyrinth, . . 374 Membranes of bones, . . .169 Mental relations of the skin, . 131 Mesenteric glands, . • . 592 Mesentery, .... 557 Meso colon, right and left, . .557 Transverse, . 556 Rectum, . . . 557, 572 Metacarpo-phalangeal articula- tion, 709 Metacarpus, . . . .699 Ossification of, . . 701 Metatarsal arteries, . . . 776 Metatarsus 750 Microscopic anatomy of the pulp, 236 Middle artery of the cerebrum, 425 Articular artery, . . 775 Cervical ganglion, . 521 Costo transverse ligament, 467 Ear 364 Meningeal artery, . . 433 Musculo-cutaneous nerve, 635 Straight ligament, . 459 Temporal artery, . . 432 Turbinated bones, . 190 Minor helicis, . . . . 363 Mitral Valve, ... 621 Mixed ligaments, . . .151 Moderator ligaments, . . 459 Modiolus of the ear, . . . 372 Molar glands, ... 323 Teeth, . . . .232 Moles, (talpidae,) ... 279 Mollusca, 47 Monkeys, .... 273 Monroe, 38 Mons Veneris, . . . 662 Morgani, 38 Morsus Diaboli, ... 671 Motores oculorum nerves, 352, 421 Externi nerves, . 353, 423 Mouth, .... 318,437 Blood-vessels of, . . 323 Boundaries of, . . 318 Cavity of, .• - . . 318 Contents of, . . , 319 Dissection of, .- • >>•'• .319 Epithelium of, . . 319 Mucous membrane of, . 319 Nerves of, ... 324 Relations with the trunk, . 684 Mucous membrane, . . 123, 134 Mucous membrane, discharges of, 141 Displacement of, . . 141 Gastro, pulmonary, . . 134 Genito, urinary, . . 134 Inflammation of, . . . 141 Malformation of, . . 141 New formation of, . . 141 Of the cheeks, . . 323 . 532 Of the larynx, Of the pharynx, Soft palate, . Relations of, Stricture of, Structure of, 323 . 323 140 . 141 135 Tumor of, . . . . 141 Vegetation of, . . . 141 Mucus, . . . . .54 Mundinus, 36 Muller Multifidus spinse, . . . 496 Muscle, chemical composition of, 146 Nucleated cell of, . . 145 Sensibility of, . . .146 Muscles, color of, . . . 143 Consistence of, . . .143 Direction of, . . . 143 Fasciculus of, ... 144 Insertion of, . . . 144 Involuntary, . . . 142 Mixed, .... 142 Names of, . . . . 143 Number of, . .143 Of the abdomen, . . 682 Anterior neck, . 481 Arm, . . . .712 Back, ... 682 External ear, . . 363 Eye, ... 349 Foot, . . . .766 Forearm, . . 714 Head, . : . . 435 Inferior extremity, 757 Internal ear, . . 369 Leg, ... 762 Mouth, . . .223 Neck, ... 681 Nose, . . .380 Pelvis, . . 672, 682 Perineum, . . . 678 Shoulder, . . 709 Superior extremity, . 709 On posterior neck and back, 488 Origin of, . * ,s . 144 Situation of, ... 142 Structure of, ... 144 Symmetrical, . . . 142 Their myolemma, • • . 144 Muscles of thigh, . . . 757 Sarcolemma, . . 144 Ultimate fibres of, . . 144 Fibrils of, . .144 INDEX. 801 Muscular contraction, varieties of, 146 Sense, . . . .146 System, .... 142 Development of, . 146 Musculi accessorii ad sacro lum- balem, . . . 493 Pectinati, . . . 618, 620 Musculo cutaneous nerve, 783, 739, 513 Muscular branches of brachial ar- tery, . . . .730 Musculo spiral nerve, . . 740 Mylo-hyoideus muscle, . . 304 Mylo-hyoid nerve, . . . 267 Mylo-hyoid ridge, . . .210 Myopia, . . . . r ^ 343 N. Nail follicle, . . . .133 Nails, 132 Names of muscles, . ''. - . 143 Nasal artery, .... 435 Bones, . . . .207 Articulation of, . 207 Development of, . 207 Structure of, . 207 Duct, . . . .358 Fossae, . . 218, 381 Nerve, . . . .354 Prominence, . . 177 Spine, ... .177 Nasmyth 39 Naso-palatine nerve, . . . 266 Ganglion, . 518 Navel, w . . . . 541 Navicular bone, Nemisius, Nerve crural, Femoral, Fibres, primitive, Of the bulb, OfWrisberg, . Splanchnic, 697 . 361 35 . 635 635 . 108 680 . 738, 633 630 Nerves, . . . •. .110 Course of, . -.' . Ill Excito-motory, . . .110 Of Bone, . . -. ' . 170 Cotunnius, ."' ; •'*.-' . 266 Mastication, ' i . 298 Motion, . .'' ; . .110 Sensation, . . . 110 The ear, . . . .375 The eye-brows . . 355 The eyelids, . . .358 Inferior extremity, . 779 The neck, . . . 509 OZsophagus, ^«i'H- . 498 The palate, . . .309 Nerves of the pharynx, . . 318 Salivary glands, 302 52 Nerves of the superior extremity, 736 Teeth, . . .262 Tongue, . 314, 379 Trunk, . . .683 Plexus of, . . . in Respiratory, . . . no Spinal origin of, . . 113 Nervi pathetici, .... 353 Trigemini, . . . 353 Trochleares, 1 . . 353 Nervous grey matter, . . 109 Chemical constituents of, 109 Layer, .... 136 Tissue, . • . , . 106 White matter, . . . 109 Chemical constituents of, 109 New formations of mucous mem- brane, .... 141 Ninth pair of nerves, . 425,510 Nipple, ..... 600 Nodule, . . • _, . 406 Non-articular ligaments, . . 151 Nose, 379 Cartilage of, . . . 330 Notches of bones, • . . . 167 Nucleated cell, . . . .64 Of muscle, . . . 145 Nucleus, . . . , .' . 63 Number of muscles, '•/".'... 143 Nutritious artery of arm, . . 729 bones, . 170 Nymphae, .... 160, 662 o. Oblique inguinal canal, . . 547 Ligaments, . . 459, 706 Process of vertebras, . 445 Obliquus capitis inferior, . . 495 superior, . 495 Externus abdom. descendens, 539 Inferior, .... 351 Internus abdom. ascendens, 542 Superior, ... 350 Oblongata medulla, . . .114 Obturator externus muscle, . 674 Fascia, .' . . .675 Foramen, « . . 474 Internus muscle, . . . 674 Ligament, . . .478 Nerve, . . . 781, 636 Occipital artery, . 429, 431, 504 Bone, ... 182 Articulation of, . .184 Development of, . 184 Structure of, . . 184 Occipitalis major nerve, "" " . 513 Minor nerve, . .513 Occipital protuberance, external, 182 Internal, 183 Sinuses, . •>•«•"• . 393 802 INDEX. Occipito axoid ligament, . . 459 Frontalis muscle, . . 324 Ocular fascia, . /, . . 352 Odontoid apophysis, ">* . . 166 Odoriferous glands, . . .129 CEsophageal nerves, . . 500 (Esophagus, .... 497 Arteries of, . . 497, 627 Olecranon process, . / , . 696 Olfactory ganglia, . ... . 420 Olivaria, . . . , , .115 Olivary ganglion, . . -,.' 401 Omentum majus, . :v . 556 Minus, . . . 556 Omo-hyoideus muscle, . . 484 Opacity of the eye, '. . 341 Opossum 282 Teeth of, . . ,282 Ophthalmic artery, . . 346 Ganglion, . .516 Nerve, ' . 353, 423 Optic commissure, . . . 421 Nerve, .... 420 Oral teeth, . . . .230 Orbicularis oris muscle, . 226 Palbebrarum, . . . 326 Orbital foramina, . . . 179 Nerves, . . . .266 Processes, . . . 179 Orbitary apophysis, , . . 166 Orbits of the eyes, l\ '. . 217 Organ, adamantine, . . . 253 Definition of, . . . 41 Enamel, . . . .253 Of taste, .... 377 Of voice, . . . .525 Organic and inorganic bodies, difference, . . .57 Life, .... 116 Relations of mucous memb., 140 The skin, . 131 Organism, what constitutes it, 41 Organization, . . . 41 Development of, . . . 57 Human constituents of, . 50 Its elements of preservation, 45 Of man, .... 50 Varieties of, . . .47 Organs of absorption, . . 590 Circulation, . . 614 [Head, active, . . 222 Neck, circulatory, . 501 Deglutition, . 303, 497 '. Digestion, . . . 554 ; Abdomen, . . 554 Head, . . .222 Expression, . 222, 324 Generation of male, . 649 Female, 661 Innervation, . . 509 Insalivation, . . 298 Organs of mastication, . . 227 Prehension, . . 223 Dissection of, . 223 Respiration, . . 605 Sense, . . 222, 330 External, . . 331 Internal, . . 331 Speech, . . 222 The abdomen, . . 527 Chest, . . 596 Neck and back, . 481 Pelvis, . . 649 Touch, . . 133, 384 Urination, . . 637 Origin of muscles, . . . 144 Os calcis, .... 749 Cuboides, . . . .749 Cuneiforme, . . . 698 Femoris, .... 742 Ilium, .... 470 Innominatum, . . . 470 Development of, . 475 Structure of, . . 475 Ischium, .... 472 Lunare, . . . .698 Magnum, , ^ . . 699 Ozmasome, 54 Os naviculare, . . 749, 697 Pisiforme, .... 698 Pubis, 473 Scaphoides, . . . 749, 697 Osseous tissue, . . . 161 Stage of bone, ..'-. r. ' . 170 Ossification of flat bones, . 172 Long bones, . 171 Period of, . 172 Os tineas, 667 Ostium venosum, . . . 618 Os unciforme, . . . .699 Uteri, .... 667 Otic ganglion, .... 518 Oto-conia of the ear, . . 375 Otter, Teeth of, . . . . 282 Ourang outang, • . . 273 Ourlet, 411 Ovarian ligaments, . . 666 Ovaries, . . . . . 669 Blood-vessels of, . . 670 Function of, ... 670 Structure of, . . . 670 Ovula Nabothi, . ... . - . 668 Ovum, . . . ';. . 670 P. Pachydermata, . . . . 283 Padua — University of, . . 37 Palate bones, .... 203 Articulation of, . . 205 Palate bones— development of, . 205 Foramina of, . . . 205 INDEX. 803 Palate bones, structure of, . Palate, arches of, Blood-vessels of, Cleft of, Hard, Nerves of, . Velum pendulum, Palatine glands, Palmaris brevis, . Longus, . Palmar ligaments, Palpebra, . . . Pancreas, .... Blood-vessels of, Function of, '. ; , Nerves of, Structure of, . '.'". • Papilla?, .... Of the hair, . Skin, . Tongue, . Blood-vessels of, Minute structure of, Parenchyma of the lungs, Parietal bones, Structure of, . Protuberance, Parotidean plexus, . Parotid gland, Par vagum nerve, . 424, Passive organs of the trunk, Patella, .... Pathetic nerve, . Pectinalis, Peccari, Teeth of, Pectineus, Pectoralis major, Minor, . Pelvic fascia, Vertebra, . * Pelvis, . . . .,- * 5. Diameters of, . .y Difference between male female, . -. -.i False, . . . \;v- General remarks upon, True, .... Of the kidney, . Penis, Blood vessels of, Nerves of, . Structure of, . Pepsin Pepsin, chemical analysis of, Pericardium, . , Perichondrium, . Perforans Casserii nerve, Periglottis, .... Perineal cutaneous nerves, Fascia, . . . Perineum of the male, . . 205 . 307 . 309 307 . 306 . 309 . 306 . 323 . 723 715 . 708 355 . 586 . 587 . 587 . 587 . 587 . 386 . 132 126 311, 378 311 379 612 . 180 182 . 181 . 329 . 299 498, 509 . 443 747 . 422 760 . 287 760 . 597 598 . 675 451 . 470 . 480 and 479 . 478 478 . 478 641 . 656 . 660 . 661 656 54, 563 . 54 • 614 155, 466 739 . 378 780 . 677 676 Perineum, blood-vessels of, . . 680 Muscles of, ... 678 Nerves of, . . . . 680 Peroneal artery, . . . 776 Nerve, . . . .783 Vein, ... 778 Peroneus longus, . . . 763 Brevis, . . ,763 Tertius, ... 764 Pes Anserinus, .... 329 Hippocampi, . . . 417 Petrosal sinus, . . . .398 Petrous portion of temp, bone, 186 Peyer's glands, .... 138 Phalanges of the foot, . . 751 hand, . . 701 Development of, 702 Pharyngeal nerve of par vagum, 499 Plexus, . 499 Pharynx, .... 314 Blood-vessels of, . . . 317 Cavity of, . . 317 Dissection of, ... 315 Nerves of, ... 318 Mucous membrane of, . 323 Phrenic artery, . . . 553 Nerve, . . . .512 Plexus, ... 631 Pia mater 389 Of the brain, . . fl . 399 Pigment granules, . . . 132 Pineal gland, peduncle of, . 414 Pinna, 361 Pisces, Teeth of, ... 292 Pisiforme, .... 698 Pituitary gland, . . » .412 Plantar arteries, . . . 777 Fascia, . . . .771 Ligament of foot, . 757 Platysma myoides, . . . 482 Plantaris muscle, . . . 765 Pleura, . . . '. . . 602 Function of, . ." . 605 Structure of, . . . 605 Plexus, Ill Aortic, . ,-• '. * •- . . 632 Choroides, :. v . . 418 Gastric, .... 631 Hemorrhoidal, . . .632 Hepatic, . . ''.-.. 631 Hypogastric, V : . . 632 Inferior mesenteric, . 631 Lumbar, .... 634 Phrenic, . . • . 631 Renal, . . k . •' . .631 Sacral, . .•••»»'" ''» " . 636 Sciatic, . . . . 636 Solar, . r V . 631 Superior mesenteric, . . 631 Plica semilunaris, . . . 357 Pneumogastric lobe, . . . 405 804 INDEX. Pneumogastric Nerve, . 424, 489 Pomutn Adami, .... 525 Pons tarini, . . . . 1 412 Pons Varolii, . . . .402 Popliteal artery, . . . 774 Vein, . . . 100,778 •Nerve, . . . 781 Popliteus muscle, . . . 765 Pori biliarii, . . . » . 581 Porta of the liver, .', ." .578 Portal canals, . . • 580 Circulation, . . .87 Portal vessels, Structure of, . 88 Portio dura nerve, . . 327, 423 Mollis nerve, -.>,.„ 423 Porus Opticus, .... 340 Posterior atlanto axoid ligament, 460 Annular ligament, . . 725 Auricular artery, . . 429, 431 Auris, .... 363 Cerebral arteries, . . 426, 427 Cervical plexus, . . 511 Circumflex artery, . . 729 Communicating artery, . 426 Costo-sternal ligament, . 467 Costo-transverse ligament, 466 Crural nerve, . . . 781 Deep temporal artery, . 434 Dental canal, . . . 198 Dental nerves, . . 264 Ganglia of the brain, . . 414 Inferior spinous process, . 472 Interosseii, .... 724 Interosseous artery, . . 733 Interosseal nerve, , . 741 Ligament of knee-joint, . 753 Crucial ligament, . . . 753 Meningeal artery, . . 431 Mental foramen, . . . 212 Occipito atlantal ligament, 458 Palatine canal, . . 198,204 Pubic ligament, . . 478 Pulmonary plexus, . 500, 612 Pyramids, . . . 402 Sacro-iliac ligament, . . 476 Sacro-sciatic ligament, . 476 Scapular artery, . . • 507 Spinal artery, . . 427, 392 Superior spinous process, . 472 Temporal artery, . . 432 Nerves, . . 268 Thoracic nerve, . . 514 Tibial nerve, . . .782 Vein, ... 778 Artery, . . .776 Vertebral ligament, . 455 Poupart's ligament, . . . 100 Praeputium clitoridis, . . 663 Prepuce, 656 Presbyopia, . . . .343 Primary convolutions of the brain, 410 Primitive lobe of cerebellum, Princeps cervicis artery, Processus cerebello ad testes, Process gracilis, . Process zygomatic, 406 . 431 407 . 368 206 Profunda'cervicis, . . 504, 507 Spiralis artery, . . 729 Superior artery, . . • 729 Femoris, . . . 773 Inferior, .... 730 Minor, .... 730 Promontory of the ear, . . 366 Sacrum, . 452 Pronator quadratus, . *•>».<, . 717 Radii teres, . . 715 Prostate gland, . .,', « .655 Structure of, . :».-.. 656 Protein, . . . . 52, 53 Psoas magnus, . . » .' •» 550 Parvus, .... 550 Pterygoid artery, . . . 434 Pterygoideus externus, . .296 Internus, . . 297 Pterygoid fossa, . . . .193 Nerve, . . 265,268 Pterigo-palatine artery, . . 435 Pterygoid process, . . . 193 Ptyalin 55 Pubis, 473 Pudic nerve, . . . .680 Pulmonary artery, . . 611,620 Circulation, . 101, 625 Glands, . . 595 Veins, . . .611 Pulmones, .... 605 Pulp of tooth, cavity of, . . 234 Microscopic anatomy of, . 236 Fibres of, ... 238 Vessels of, . . . . 234 Functa lachrymalia, . , » 359 Punctum aureum, .... 340 Lachrymale, . 4 «* -n . 355 Ossificationis, . : . . 171 Pupil of the eye, . . . 337 Purse-like fissure, . . . 404 Pyin, . . U >^T^.<. 55 Pyloric valve, . • . • .^ . 563 Pyraformis, . •.<;•.' -. 674 Pyramidalia, . -. . i» . • . 115 Pyramid of the ear, v-'?'. 366 Of inf. vermiform process, 405 Pyramidalis muscle, . . 545 Pyramides Malpighi, . • . . 640 Q. Quadratus femoris, Lumborum, Menti, Quadrilateral spot, Quadrumana, 675 549 225 411 273 INDEX. R. Racoon, teeth of, . Rachidian bulb, . Radial artery, >"$*•' Nerve, . Radialis indicis artery, 282 400 731 740 731 Radiata 47 Radiated ligament, . . 702 Ligament of head of ribs, . 466 Radio-carpal ligament, . . 706 Radius, 694 Development of, . . 696 Structure of, . . .695 Ramus of Ischium, •.- . 473 Pubis, . . .474 Profundus dorsalis, . 741 Superficial ant'r nerve, 741 Dorsalis,. . . 741 Ranine artery, .... 430 Receptaculum chyli, . . 122 Reil's estimate of heart's force, . ]03 Pectal fascia, ... 675 Recto uterine ligament, . . 666 Vesical fascia, . . 675 Rectum, . . : . .573 Rectus abdominis, . . . 544 Capitis anticus major, . . 487 Minor, . 487 Femoris muscle, . . . 758 Capitis lateralis, . . . 488 Posticus major, . . 494 Minor, . . 494 Externus, .... 350 Inferior, .... 350 Internus, » -. •.-.*• . ..-. . 350 Superior, v.,4 , • . . 349 Recurrens ulnaris, posterior, . 732 Radialis, .... 731 Ulnaris, (anterior,) . . 732 Recurrent nerve of par vagum, 500 Reflections of dura mater, . 395 Regions of abdomen, . . . 537 Skull, . .215 Regie pubis, .... 538 Relations of cartilaginous system, 159 Of fibrous system, . . 156 Mouth and head, . . 437 Mouth and extremities, 785 Mouth and trunk, . 684 Mucous membrane, . 140 Organic, . 140 Organic of skin, . . 131 Of skin, . . . .130 Renal artery, . . . 641, 627 Capsules, . . . .641 Plexus,. . .631 Reptilia, teeth of, ... 290 Reptiles, .... 48 Respiratory nerves, . . .110 Restiforme, . . . .115 Rete Malpighi, .* Mucosunij >:-v Testis, t Reticular tissue, Retina, structure of, . Rhinoceros, teeth of, Rhomboid ligament, . Rhomboideum, corpus Rhomboideus major, . Minor, Ribs, . Development of, Ridges of bones, Rima glottidis, 805 101 125 652 167 339 285 703 407 490 490 463 465 165 528 Right auricle, . . . .616 Auriculo ventricular opening, 618 Coronary artery, . . 624 Epiploic artery, . . . 563 Lateral ligament, . . 577 Meso-colon, . . . 572 Ventricle, ... 618 Rodentia, Teeth of, . . 272, 282 Rotula, 747 Rudbeck, 38 Ruminantia, Teeth of, . . 288 Ruysch, Frederick, . fe . . 38 S. Sacculus communis of the ear, . 375 Laryngis, . . 532 Proprius of the ear, . 374 Sacral foramina, . . . 451 Nerves, . *<>4t*a* . 636 Sacciform ligament, . . 708 Sacro iliac articulation, . . 476 Sacro-ischial articulation, . 476 Sacro-lumbalis muscle, . . 492 Sacrum, .... 451 Development of, . . .453 Salernum, .... 35 Saliva, 302 Salivary glands, • . . 298 Blood-vessels of, . . . 302 Nerves of, . . .302 Sanctorius, . ... .130 Saphena veins, . . . 778 Sarcolemma of muscles, . . 144 Sartorius, . . . . 758 Scalse of the ear, . . .372 Scala tympani, . . . 372 Vestibuli, . . . .372 Scalenus anticus, . . . 486 Medius, . . .486 Posticus, ... 486 Scales of epithelium, . . . 135 Scaphoides, . .,* '- *;. . 697 Scaphoid fossa, . . ,-*".. . . 361 Cellular, quantity of, . 77 Relations of, . . 78 Cutaneous, -* ; .. . 123 806 INDEX. Scapula, ... . . 689 Development of, . . .691 Structure of, . . . 691 Scapularis inferior artery, . . 728 Scapulo clavicular articulation, 703 Scarpa 38 Schindylesis, . . . .152 Schneiderian membrane, . 383 Schwann, 39 Sciatic Nerves, . . 781,780 Nerves, .... 637 Sclerotic coat of the eye, . 332 Scrobiculus cordis, . . . 538 Scrotum, . . , y • i 649 Sebaceous fluid, . . ,. V .129 Glands, . . 129 Secondary convolutions of brain, 410 Second pair of nerves, . . 420 Secretions of the skin, . . 130 Sella Turcica, . . . .192 Semicircular canals, s • -, 373 Semilunar cartilages, . . . 754 Ganglion, . . 630 Lobe, . . .405 Valve, . ,V . 619 Semimembranosus, i ,\ . . 761 Semi spinales colli muscle, . 495 Dorsi muscle, . 495 Semitendinosus, . . . 761 Sensation, *J. ,. > . . . . 330 Of the skin, ... 129 Sensibility, . . . .65 Of muscle, . .,•«:.*': . 146 Septum auricularum, .. ••, . 618 Cordis, . . . 621 Lucidum, . . 417, 419 Pectiniforme, . . 657 Serous tissue, . . . .80 Form of, . . . . 80 Structure of, ... 82 Serpents, Teeth of, . . 291 Serrated suture, . . .152 Serratus major anticus, . . 598 Posticus superior, . 491 Inferior, . 492 Serum, 71 Seventh pair of nerves, . . 423 Sheath of arteries, . . . 93 Tendons, . . 154 Shedding of the teeth, . . 246 Short bones, .... 162 Thoracic artery, . . . 728 Shoulder blade, . , . :i;. * 689 Shrews (solicidae,) . , . . 279 Sigmoid cavity, greater, /..- , 697 Lesser, . . 696 Flexure of the colon, . 573 Valve, . . . .619 Simia3, 273 Sinus, circular of Ridley, . . 398 Sinuses, 166 Sinuses, cavernous, . . • 398 Lateral, .... 397 Occipital, . . . .398 Of the brain, .. . . 628 Dura mater, . . • 396 Valsalva, ... 620 Petrosal, . . . .398 Sinus frontal 173 Inferior longitudinal, . - 397 Pocularis, ... 659 Superior longitudinal, . . 396 Transverse, ... 398 Vena portarum, . ;. <»'• . 580 Sixth pair of nerves, . . 423 Skeleton, Artificial, . .. . 162 Natural, . . 162 Division of, . .162 Skin, 123 Papillae of, . . . .126 Relations of, . . . 130 Structure of, •:-..; ,.- ; . 125 Skin, Appendages of, . . 132 Skull, general development of, . 221 Regions of, . . . 215 Sloth, Teeth of, . . k>;H . 283 Soft palate, .... 306 Solar Plexus, . .' \V . 631 Solitary glands, . .139 Soemering, . . . .38 Sounds of the heart, . . 625 Spermatic artery, . . 627, 654 Cord, . . . .653 Spermatin, . . 54 Sphenoid bone, . . .f . .-* .192 Spheno maxillary fissure, . 198 Palatine artery, . . 435 Foramen, . 205 Ganglion, . 517 Nerve, . 266 Sphincter externus, . . . 678 Internus, -.-••' « 678 Vaginae, . . .680 Vesicae, *Y.%.. . 647 Spinal accessory nerve, . 424, 5l<9 Spinalis dorsi, -^ • • 493 Spinal marrow, . . . 112, 387 Blood-vessels of, . 392 Nerves of, . . .391 Nerves, ganglia of, . 391 Origin of, . 113,391 Spine, . . . -/. . . 443 Of the pubis, . . .473 Spines, ..... 166 Spinous process of the ischium, . 473 Vertebra?, 445 Splanchnic nerve, . . .514 System, . . 116 Spleen, . . . .. , .• . 589 Blood-vessels of, . . 590 Function of, ... 590 Lymphatics of, 590 INDEX. 807 Spleen, nerves of, ... 590 Structure of, . . . 589 Splenic artery, . . . 590, 627 Plexus, . . . .631 Splenius capitis et colli, . . 492 Spongy bones, . . . 207 Squamous epithelium, . . 319 Portion of temporal bone, 184 Suture, . . . .152 Stapedius muscle, ... 369 Stapes, . • ... j .•_• . . . 368 Stellate ligament, ... 466 Steno'sduct, . . . 226,300 Sternal articulation of the ribs, 467 Sterno clavicular articulation, . 702 Ligament anterior, . 702 Posterior, . 702 Cleido mastoideus muscle, 482 Hyoideus muscle, '••*. .483 Thyroideus, ... 484 Sternum, . . . * ' . 460 Development of, . . 462 Stimuli, vital, . . . . 45 Stomach, . . ..."••". 558 Blood-vessels of, . . . 563 Function of, . . . 564 Nerves of, . . • . ' . 563 Structure of, . . . 560 Striata corpora, . . . 108 Stricture of mucous membrane, 141 Stroma, 669 Structure of bone, . . 167 Cartilage, . . 157 Dentine, . . 239 Frontal bone, . 180 Mucous membrane, 135 Muscle, . Occipital bone, . Parietal bone, Teeth, Styloid apophysis, Process, Of the radius, . Stylo-glossus muscle, Hyoideus muscle, '• ' ' Hyoid nerve, . . ^ • Mastoid artery, . , ' ; Maxillary ligament, Pharyngeus muscle, Sub-arachnoid spaces, Clavian artery, Veins, . Clavius muscle, . Lingual artery, Gland, . Lobular veins, Maxillary ganglion Gland, Nerve, Mental artery, . Mucous Layer, 144 184 382 234 166 186 695 306 306 329 432 215 316 399 627 . 509 . 600 430 . 301 583 . 517 . 300 . 330 430, 504 . 136 504, Sub-pubic ligament, . 478, 676 Scapular artery, . . . 728 Nerves, . . 737 Scapularis muscle, . . 711 Substantia perforata anterior, . 411 Sudoriferous glands, . . 128 Sugar of milk, . . . .56 Supercilia, .... 354 Superciliary arch, . . . 178 Superficial abdominal fascia, 545 Cervical fascia, . . . 522 Circumflexa ilii, . . 773 Epigastric artery, . • 773 Superficial colli nerve, . 511 Volae artery, . . .731 Superficial perineal artery, . 680 Superior articular artery, . . 775 Cerebellar arteries, . . 427 Cervical ganglia, . • 520 Coronary artery, . 227, 431 Costo-sternal ligaments, . 467 Dental artery, , 261, 434 Extremity, . . . .689 Ganglia of cerebrum, . 416 Intercostal veins, . . 509 Laryngeal artery, . . 503 Nerve, . . . .500 Longitudinal sinus, . 179, 396 Maxillary bone, . . .196 Development of, . 203 Foramina of, . . 202 Process of, . . 202 Structure of, . . 202 Nerve, . . 423,263 Mesenteric artery, . . 627 Plexus, . . 631 Musculo-cutaneous nerve,' . 635 Palatine artery, . . 434 Palpebral sinus, . . . 356 Pelvic aponeurosis, . . 675 Pharyngeal artery, . . 435 Pubic ligament, . . 478 Scapular artery, . . . 506 Strait of the pelvis, . . 478 Thoracic artery, . . . 728 Thyroid artery, 503, 428, 429 Turbinated bones, . . 190 Vena Cava, . . 101, 628 Vermiform process, . . 405 Supinator radii brevis, . . 719 Longus, . . 717 Supra-clavicular nerves, . 514 Orbital nerve, . . . 354 Ridge, . . 178 Renal plexus, . . . 631 Scapular nerves, . . 737 Spinalis, . . ' . .496 Spinatus, .... 710 Spinous fascia, . . . 725 Ligament, . . 457 Trochlear nerve, . . 353 808 INDEX. Suspensory ligament, . 556, Of the penis, . . 576 657 Temporal artery, structure of, . Fossa, . . . * . 188 193 Sural arteries, .... Sutura, 775 159 Temporalis muscle, Temporal nerve, . ^ , >' 295 320 Sutures, Sylvius, Symmetrical muscles, Sympathetic nerve, . 514, System, . « 195 37 142 629 116 Ridge, • : W • Temporary teeth, . Temporo-facial nerve, Tendons, . . . 147, 181 244 329 153 396 Symphysis, .... Menti . 153 209 Tensor palati, Tarsi, .... 308 351 Pubis, .... 474 Tympani, . 369 Synarthrosis, . . . . Syndesmology, Sy no vial membranes, 83 152 150 Vaginae femoris, . •'.* Tentorium, ... ,..;> 758 395 711 Syssarcosis, . . . •,*.>. Systemic circulation, . • • • 153 695 Minor, . . . Testes, . . • . 711 649 Swammerdam, . » .r. • . T. Tactile papilla, ,r v',"''; V. \,V> 38 133 335 Of the brain, . . ;. * Blood-vessels of, . , , • • Function of, . . » ; Lymphatics of, . . .:,, ,». Nerves of, . . \ ^ . .» •; Thalami optici • ' • • * V 413 654 654 654 654 414 Tsenia hippocampi, . . .'!. Semicircularis, . « Tarsal arteries, . .' . . . Cartilages, . . -.' Tarsus, . . . Tartar glands, . . " . 417 417 776 356 748 322 Theca vertebralis, . . .,,. Third pair of nerves, ...... ;. ., K. Ventricle, . », .*, .' Thoracica acromalis artery, Thoracic duct, . . 121, Left, . ' , 388 421 416 728 122 595 Teeth,. . .^ V' . . 997 Riffht 596 Bicuspids, . , 232 737 Blood-vessels, Canine, or cuspidati, . 259 930 Spinal nerves, . . • » , Thorax, . . • ' "*. . 632 460 Cavity of reserve, %". . Classification of, Comparative anatomy of, Description of, Difference between, and bone, Temp, and permanent, Eruption of temporary, Follicular stage of, . Functional relations of, Grand division of, . Irregularities of, . . ', Molar, . . . v ' 251 228 268 229 247 246 244 259 258 228 247 939 Thymus gland, Blood-vessels of, . Function of, Lymphatics of, Nerves of, . Structure of, ^,, Thyro-arytenoideus, Arytenoid ligament, •< : : , Epiglottideus, . . • Ligament, Hyoideus, . . .. (•., Hyoid ligament, » • , . 613 613 613 613 613 613 530 528 531 528 529 597 Nerves of, . . ' . ' . Of Mammalia, ' '. ' • 262 970 Membrane, . ;» i 527 506 Oral, Origin and development of, Papillary stage of, Permanent, eruption of, . Saccular stage of, . ,'. • 230 248 250 245 950 Cartilage, . . . , Foramen, . . .. Gland, arteries of, . Nerves of, Tibia 525 474 524 525 745 Shedding of, . " V ' " • ^ Structure of, . . "' ". Varieties of, . . . , Temp'l artery, and branches, 429, Bone, .... Articulation of, . Development of, . Foramina of, . . . Processes of, . 246 234 258 432 184 189 188 188 188 Tibialis anticus, .... Posticus, . Tissue, adipose, quantity of, Cartilaginous, Capillary, . Cellular, Continuity of, . . Division of, . Form of, . 762 766 79 156 84 75 77 77 76 INDEX. 809 Tissue, erectile, . Glandular, Muscular, Nervous, > . "' « Osseous, Reticular, Serous, form of, . Vascular, Tissues, . Number of, Origin of, . Physical properties of, Vital properties of, Tongue, .... Blood-vessels of, . Chorion of, . * Papillary membrane of, Periglottis of, . Nerves of, . . . Tonsil, .... Lobe, . Torcular Herophili, Trab'eculae septulae, . . Trachea, Blood-vessels of, . Nerves of, Structure of, . • . ; ,« Trachelo mastoideus, . Tract of nervous matter, Tractus opticus, Tragicus muscle, Tragus, .... Transversalis abdominis, Cervicis, . Colli, .... Pedis, . Perineii, . Transverse colon, Compressors, . Facial artery, Fissure of liver, Ligament of atlas, • ,' Meso-colon, Perineal artery, . Process of vertebra, Sinuses, Transversus auriculae, Perineii artery, . », Trapezium, . . - . Trapezius, . .- i . Trapezoides, . Triangles of the neck, Triangularis oris, . Sterni, . Triangular ligament, Triceps extensor cubiti Tricuspid valve, Trifacial nerve, . Trigemini nerve, . Trigone vesical, . Trochanter major, . 676, . 160 117 . 141 . 106 . 161 167 . 80 83 . 63 66 . 63 65 . 65 310, 377 . 313 378 . 378 378 . 379 137 . 405 184, 398 . 658 . 534 . 536 536 . 534 . 494 . 110 . 421 . 363 361 . 543 . 494 494, 507 . 768 679 . 573 . 680 227, 432 578 . 459 556, 572 . 680 445 . 398 . 363 . 680 698 . 488 698 . 484 . 224 . 600 704, 707 . 713 619 . 422 . 422 . 648 . 744 Trochanter minor, . . 744 Trochanters, .>.-•«•.«* 166 Trochlea of humerus, . .694 Trochlearis nerve, . . 353, 422 Trochlea, 694 True pelvis, . . . .478 Trunk, 443 Blood-vessels of, Nerves of, Tuber- Annulare, Cinereum, . Tubercle of the radius, Tubercula quadrigemini, Tuberculum Loweri, . Santorini, . Tuberosities of bones, . Humerus, Ischii, . Tuberosity of superior maxillary bone, .... Tubular portion of the kidney, . Tubuli seminiferi, . Tubulus centralis modioli, . Tumor of mucous membrane, Tunica albuginia, Arachnoidea, Function of, - Conjunctiva, Erythroides, . Propria, ., . Ruyschiana, . Vaginalis testis, . Vasculosa, Turbinated bones, . Tusks of the elephant, Tympanic artery, . Nerve, Plexus, . . . „.„ Tympanum, .... 364 Lining membrane of, . 370 683 . 683 . 402 . 412 . 695 108, 413 . 617 527 . 165 693 473 198 640 651 373 141 651 398 399 356 650 252 334 650 651 190 341 433 329 376 u. Ulna, .... Capsular ligament, Development of, . Structure of, . Ulnar artery, Nerve, . Umbilical Fissure, Ligament, Region, Vein, . Umbilicus, . Unciforme bone, .^ Unguiforme bones, Urachus, Urea, . . > ^ , Ureters, . • . • , * Urethra female, . , Urethra male, . Uric acid, . " . . 696 706 697 697 732 740 578 645 537 581 541 699 206 645 55 643 663 658 56 810 INDEX. Uterine arteries, >. M, •. 668 Uterus, 665 Blood-vessels of, . . 668 s Function of, ... 669 Lymphatics of, . . 668 Nerves of, . . . . 668 Structure of, . • . - , 667 Uvea, . 337 Uvula, . . ....-•* 406 V. Vagina, .... 160, 664 Structure of, . ,'. - . 665 Vaginal ligament, . . . 726 Plexus, . . ,.:•>;. 583 Valley fissure, . . . .404 Valve of Eustachius, . . 617 Thebesius, . . .618 Vieussens, . 407, 414 Valvula Conniventes, . . . 566 Varieties of muscular contraction , 146 Vasabrevia, . . . .563 Efferentia, . . 120, 591 Inferentia, . . 120, 591 Vasorum, ... 93 Vascular tissue, . . . .83 Vasculum aberrans, . . 653 Vas deferens, .... 653 Vastus externus, . .' ••-. ..k 759 Internus, .... 759 Vegitations of mucous membrane, 141 Vein of Galen, . . .,, -. ' . 397 Popliteal, . . iti . . 100 Veins of bones, . . . .170 Of inferior extremity, . 778 Of the neck, . . .507 Of superior extremity, . 735 Valves of, . . . .93 Velum interpositum, . 414, 418 Palati, 307 Vena Galeni, .... 397 Innominata, .... 508 Portarum, ... 580 Salvalella, . . . .735 Venae cav» hepaticse, . . 581 Venous circulation, . . .99 Venter of the ilium, . . 471 Ventricle of Morgagni, . . 532 Ventricles, lateral, , ;.> . 4J7 Ventriculus, .... 558 Vertebrae, .... 443 Cervical, . . . . 446 Dorsal, . . , ,. . 449 False, . ;. S - . .443 ; Lumbar, . . V . 450 Pelvic, '. ' •'. .' . 451 True, . / / . . 443 Vertebra prominens, . . . 448 Vertebral artery, . . 426, 505 Column, .... 443 Sinuses, . . ' . .388 Vein, 509 Vertebrata, principal divisions of, 48 Vertebro sternal ribs, . . . 463 Vesalius, . v . 36 Vesical fascia, . . . .675 Triangle, • . . . 648 Vesica urinaria, . . . 643 Vesico-uterine ligaments, . 666 Vesiculae seminales, . . . 655 Vessels, lymphatic, . . 121 Veru montanum, . . . 659 Vibrisse of the nose, . - 381 Vidian canal, . . . .193 Nerve, . . 265, 328, 376 Villi 566 Of the intestines, . . 136 Villous coat, .... 561 Vitreous humor, . . . 345 Analysis of, ... 345 Blood-vessels of, . 345 Voluntary muscles, . . . 142 Vomer, 208 Articulation of, . • 208 Development of, . • 208 Structure of, ... 208 Vulva, 662 w. Walls of abdomen, . . . 539 Weasel, teeth of, . . . 282 Wharton's duct, . . . .301 White fibrous tissue, . . 149 Winslow, . . . . .38 Wirtsungius, .... 38 Wistar, 39 Wrisberg, nerves of, . . 633 Wrist, 697 X. Xiphoid cartilage, . . . 462 Y. Yellow fibre, elasticity of, . . 149 Fibrous tissue, . . 149 Ligaments, .... 456 z. Zygomatic fossa, . . . .193 Process, ./,-'. 206 Zygomaticus major, . . . 225 Minor, . . 225 Zonula ciliaris, . .-.-.. • 340 RETUR 14 DAY USE ETURN TO DESK FROM WHICH BORROWED This book i^cJne^rr die last^t^^a«i?e^ below, or on the date to which renewed. Renewed books are subject to immediate recall. .tflM 3 Iflftl LD 21-50m-6,'59 (A2845slO)476 General Library University of California Berkeley Hi