LVN 3N.D.03W JO A. V. .11 IVNOIIVN * ZW I. ^ S CINE NATIONAL LIBRARY OF MEDICINE N A T I O N Al 11 B R A R Y O F M E D I C I N I ivn jNOiasw jo A»vmn iv NOI1VN 3NI3IQ3W JO ABVUail IVNOIIVN CINE N ixy^'1 AT.ONAL LIBRARY OF MEDICINE NATIONAL LIBRARY OF MEDICINE ? Illll IVNOIIVN 3NI3IQ3W JO 11*1111 IVNOIIVN 3NI3IQ3W JO A»V»S 11 TV CLASS-BOOK OF ANATOMY, DESIGNED FOR SCHOOLS, EXPLANATORY OF THE FIRST PRIN CIPLES HUMAN MECHANISM AS THE BASIS OF PHYSICAL EDUCATION ^ BY JEROME V. C. SAjUTH, M. D. 55_ « —— for I am fearfully and wonderfully BOSTON: ALLEN AND TICKNOR 1834. Entered according to Act of Congress, in the year 1834, By Allen and Ticknor, in the Clerk's Office of the District Court of Massachusetts St; 1231 5653c PREFACE. The object of the following pages will be readily un- derstood ; and should the work, in the hands of public instructors, be instrumental in explaining to the young, for whom it was designed, a general knowledge of their own curious organization, it may lead to the adoption of such habits in early life as will insure health in youth, and intellectual vigor in age. The questions interspersed through the book are far from embracing all the subjects adverted to in the sev- eral natural divisions of the text:— they are merely ex- amples of the best mode of conducting the study, leav- ing it entirely with the teacher to select such parts for recitation as he may conceive most advisable. Technical words have not been wholly avoided ; — such as have been retained, are for the master, and not for the pupil, to aid him in acquiring a more minute and VI PREFACE. exact knowledge of the science, that he may be the bet- ter prepared to assist those who are intrusted to his care. Should the volume meet the approbation of those who are devoted to the best interests of mankind, it will not have been written in vain. J. V. C. Smith. Quarantine Ground, > Port of Boston. ) Jan. 1834. CONTENTS. Page. The Bones,—Osteology, 2 The Ligaments, — Syndesmology, . 45 The Muscles,—Myology, 50 Apparatus of Joints, — Bursology, . 114 Fluids, — Angiology, . . . . 115 The Nerves, — Neurology, . . 153 The Senses, ...-•• The Ear, ...••• The Eye,..... 175 . 175 205 Feeling, or Touch, . Smelling, ...••• Tasting, ...••■ 240 240 241 The Glands, — Adenology, 242 The Viscera, — Splanchnology, . 258 The Fluids, —Hygrology, The Skin, . . 269 272 ANATOMICAL CLASS BOOK. Anatomy is a useful science, which explains the nature, office, and structure of every part of the human body. From remote antiquity, men of learning and persevering industry have labored to comprehend and explain the complicated machinery of man, but at no period has the subject been better understood than at the present. By the study of this science, the condition of the species has been ameliorated ; extreme sufferings have been avoided ; and in the aggregate, human life has been prolonged. On the minds of youth the influence exerted by a con- templation of their own physical condition, founded on a general knowledge of the situation and functions of the different organs, must certainly have a beneficial tendency. As they discover the exact regularity of parts; the beauty and harmony resulting from particular combinations of machinery, endowed with a high degree of vitality, on the action of which, health, life, and happiness, are constantly depending, surely, it would be strange indeed if they did not fall, in humble adoration before that Supreme Intelli- gence which created, and which sustains them in ex- istence. 1 2 ANATOMICAL CLASS BOOK. Comparative anatomy, implies a dissection of the infe- rior animals, as birds, fishes, reptiles and even plants, in order to demonstrate, analogically, the functions of similar apparatus in man. This is an exceedingly useful pursuit, and though philosophers have apparently been guilty of unnecessary cruelties, it was not from a desire of gratify- ing a malevolent disposition;— on the contrary, all their researches have had reference to relieving mankind from some of those manifold evils, to which the splendid me- chanical organization of the frame is predisposed. ANATOMY IS DIVIDED INTO NINE PARTS. Os-te-o!-o-gy, which treats of the bones. Syn-des-mol-o-gy, " " " ligaments. My-ol-o gy; " " " muscles. Bur-sal-o-gy, " " " apparatus of joints. An-gi-ol-ogy, " " of vessels, as veins and arteries. A-den-ol-o-gy, " " of the glands. Splanch-nol-o-gy, " " " viscera, as the stomach, &c. Hyg-rol-o-gy, " " " fluids, as the blood, bile &c. OSTEOLOGY. All the bones, in manhood, are hard, and almost insen- sible, being composed of earth and lime, held together by means of gelatin, a kind of glue, secreted by appropriate vessels. The substance of the long bones, as, for exam- ple, those of the limbs, are compact, excepting at their extremities, where they become irregularly larger, and slightly spongy. They are classed in the following man- ner : — r 1. Cylindrical, — bones, as in the arms. < 2. Flat, — bones, as in the shoulder blades. C3. Irregular, — bones, as the ribs and those of the skull. ANATOMICAL CLASS BOOK. 3 THEY ARE FURTHER SUBDIVIDED INTO, First,—hollow bones, pbssessing marrow. Second,— flat bones, or those destitute of marrow. Before arriving at about the age of twenty, the ends of the bones are considerably spongy, and imperfectly united to the main shaft, — and, therefore, termed epiphises, from two Greek words, meaning to grow upon, but afterwards, they become firmly united. The names of a majority of the bones are very arbitrary ; some of them, however, have their appellation from a fan- cied resemblance to some object; others, are named from their shape, connexion, or supposed, or real use. Every cavity, hole, or prominence, even to the burden of the science, has also a name, — a knowledge of which is a key to the parts, either directly in contact, or lying in the immediate vicinity. Protuberances are termed processes, and are generally the points of attachment for muscles or ligaments;—the first being the moving power, and the latter, the bands which keep the ends of any two bones in juxtaposition. A natural skeleton is one, the bones of which are held together by the original ligaments. Remarkable speci- mens of these kinds of preparations are common in mu- seums, and cabinets of curiosities. An artificial skeleton, is one, the individual bones of which are united together by wires. In the human skeleton, there are two hundred and fifty- two separate bones. Those who labor hard, have some- times an extra number, which form near the joints of the thumb, fore finger, and toes. They are called sesamoids, from their resemblance to the seed of the Sesamum plant. They are useful in increasing the power of the muscles wherever they grow. 4 ANATOMICAL CLASS BOOK. THE SKELETON IS DIVIDED INTO First, — the head. Second, —the trunk. Third, — the extremities. FIRST DIVISION. There are fifty-five bones entering into the composition of the head, by including thirty-two teeth. EIGHT BONES IN THE SKULL. One os frontis,— above the eyes, constituting the forehead. Two ossa parietalia, — making the sides, above the ears. Two ossa temporum, —or temple bones. One os ethmoides,— or sieve-like bone, lying between the brain and root of the nose. One os sphenoides, — being the bottom of the skull, nearly concealed. One os occipitis,— at the lower and back part of the head. FOURTEEN BONES IN THE FACE. Two ossa maxillaria superiora, — the two making the upper jaw. Two ossa malarum,— or prominent cheek bones. Two ossa nasi,— one each side, making the arch of the nose. Two ossa lachrymalia,—just within the angle of the orbit of the eye. Two ossa palatina, — in the back part of the roof of the mouth. Two ossa turbinata,— within the nostrils. One os vomer, — the partition in the centre of the nose. One os maxillare inferius,— the under jaw. THIRTY-TWO TEETH. ( Eight incissores,— front, or cutting teelh;—four in each jaw. JJ \ Four cuspidate?, — eye teeth, two above and two below. =j < Eight bicuspides,— or small double teeth, with two cutting points. O J Eight molares,— grinding teeth. \ Four sapientiae, — wisdom teeth. ANATOMICAL CLASS BOOK. 9 THE CONNEXION OP BONES. When united with one another, in a way to admit of motion, the union is termed diarthrosis. Bones united in a manner admitting of no motion at all, are said to be connected by synarthrosis. And when they are joined by the intervention of any substance, it is called a union by symphysis. The round head of the thigh bone, rolling in its deep socket, is an example of the moveable connexion, or diarthrosis. All the bones of the head present a union by synarthrosis. In the racking, or twisting motion of the vertebrae of the spine, we find an illustration of the last division; between every two bones, there is an elastic substance to keep them from coming in contact; this is symphysis. STRUCTURE. All the large, round bones, particularly of the arms and legs, are hollow, for two purposes, — viz. 1st, because they are stronger for being hollow; and secondly, they are store-houses. The marrow is not placed in the cavi- ties to keep the bones from being brittle, but to supply the system with food when the stomach cannot, or does not perform its digestive office. During a long course of sickness, we take little or no food; — but as nutriment must be provided, to keep a proper quantity of blood in existence, — where does it come from? Under such circumstances, the marrow, which has been in store from the hour of birth, for such an emergency, is now carried from the bones and convert- ed into blood. When that has been exhausted, then the fat, wherever it exists, is next taken, — till the body be- comes almost a skeleton. This is the reason a sick person becomes poor and lean. A scanty supply of food, leads to the same result, hence 10 ANATOMICAL CLASS BOOK. horses and other animals are poor, because they are partly nourished, by converting a part of their own bodies into food. As soon as the stomach is abundantly supplied again, and is able to pursue its accustomed labor, the marrow and fat, which were borrowed, are all returned and packed precisely as they were before. BONES OF THE SKULL. The head is divided, in the first place, into cranium and face. It is a curious fact, that no two heads are shaped pre- cisely alike; indeed, there is nearly as much diversity in this respect, as there are expressions of the face. During the early periods of infancy, the bones are so flexible, that the skull may be moulded into various forms, without injury to the brain. Many barbarous nations, from immemorial time, have practised the art of changing the natural shape of the heads of their children, either to give them some characteristic of the tribe to which they belong, or to render them more beautiful, according to their rude conceptions of that quality. Observation on the natural differences presented in the skull, first gave rise to the study of craniology, which was refined upon, till it has finally resulted in the modem science of phre- nology, Calvaria, is a term to express the top, or convexity of the head. The forehead is the sinciput, and the back part, the occiput. forehead. — Osfrontis. Having remarked that the skull is composed of eight bones, it is only necessary to describe them individually, in a very general manner. The os frontis is a single bone in the adult, though in infancy it was in two pieces. ANATOMICAL CLASS BOOK. 11 Though thin and delicate, it is in two plates, whose flat surfaces have between them a porous space, called diploe, where the blood vessels are safely lodged for nourishing it. Over each eye, it throws out a protuberance, marked . by the eyebrows; — and within the orbit, a thin sheet- like process juts backward, to support the brain from pressing on the globe of the eye. Between the two plates, on a vertical line with the nose, and just between the arched ridges, the two plates recede from each other, so far as to leave a large cavity, —the frontal sinus, which freely communicates v.-ith the two nostrils, although a par- tition, extends from the nose up through the chamber. On this apartment, seems to depend the strength of the voice. Fig. 3 Explanations of Fig. 3. Front view of the single bone constituting the fore- head : a, a, mark the place of the frontal sinus, or vocal cavity: 6, the temporal ridge ; c, the nasal process, where the bones of the nose are joined ; e, e, the external angular processes f, f, the orbitar plates, above the eye, to sustain the brain. It is a drum-barrel, in effect, being for the purpose of reverberating the sound, by which its sonorous power is increased. While suffering from a severe cold, the char- acter of the voice is changed, and it is usual to remark the person talks through the nose. This alteration, how- ever, is to be imputed to the closing up of the passage, between the nose and sinus, which wholly prevents the sound from penetrating the only spot in which its volume 12 ANATOMICAL CLASS BOOK. or tone can be increased. Snuff takers, by the practice of a vile habit, very much impair, and in protracted caseB, completely ruin their voices, by obstructing the canal. wall, or parietal bones. — Ossa parictalia. These are on one side convex, and concave on the other, and of a square figure. They lie on each side of the head, above the ears, and sustain the office of walls : small holes are discoverable through one or both of them, through which veins return blood to the great canal with- in the skull. occipital bone. — Os occipitis. Of all the cranial bones, this is the strongest, thickest, and most compact. It needs to be so, inasmuch as many large muscles on the back of the neck, are inserted into it. Its shape is very much like a skimmer, having one large hole in it, about an inch in diameter, through which the spinal marrow passes out from the brain, on its pass- age down the spine, — hereafter to be noticed. After these remarks, it will be inferred that its locality is at the back and lower part of the skull. wedge, or sphenoid bone. — Os sphenoides. Being entirely concealed, unless the skull is turned bottom upwards, some difficulty is found in learning its re- lations. Nearly all writers have compared it to a bat, with wide spread wings. Through it, many nerves and vessels pass out; particularly the optic nerves, and those which supply the teeth, often so painful, in the under jaw. temple, or temporal bones. — Ossa temporum. On these bones, there being one on each side, the ears are fixed. They stand between the osfronlis,parietal ANATOMICAL CLASS BOOK. 13 Explanations of Fig. 4. a the thin squamous portion of the temporal bone, joining the skull, on a line with the top of the ear; b, the zygomatic process, which meets the cheek bone; f, a cavity in which the lower jaw is articulated; d, the external opening of the ear ; e, the styloid process ; f, the vaginal process ; g, the mastoid process. and sphcenoid bones, — reaching a little way up the tem- ple. In one part of these irregularly shaped bones, the splendid apparatus of the organ of hearing is contained, which will be fully explained in the proper place. Here is one quite prominent process, called the mastoid, which may be felt behind the ear, to which the muscle is fixed that brings the head forward, as in bowing. sieve, or ethmoid bone. — Os etlunoides. Because it is perforated with many holes, like the top of a pepper-box, or sieve, it has received its present name. It lies horrizontallv, on a level with the eyes, — being over the nose, and has the front lobes of the brain resting upon it. Through the numerous orifices, fine threads of nerves, the olfactories, pass into the nasal cavities, to constitute the sense of smelling. SEVMS OF THE HEAD, OR SUTURES. All the bones of the head are interlocked by ragged edges, called sutures. When one over-laps another, as in the case of a part, of the temporal, over the parietal bone, it is termed a false suture. All the true sutures are zig- zag lines, seen on the top and sides of the head. 2 14 ANATOMICAL CLASS BOOK. One of these lines, reaching from one ear to the other, over the top of the skull, is the coronal suture, — so called because an ornament was placed there, by the ancients. The os frontis meets the ends of the parietal bones to make this suture. Fig. 5. Explanations of Fig. 5. a, a, the coronal suture ; b, sagittal suture ; c, the lambdoidal suture; d, d, ossa triquetra, small, rag- ged bones, occasionally found in some skulls, lying in the last mentioned su- ture ; e, e, portions of the temporal bone, overlapping the walls. On the back of the head, the occipital bone is united to a portion of the temple, and the wall bones, by the lamb- doidal suture, — which has its name from its resemblance to the Greek letter L. Between the parietal, or wall bones, exactly on the highest point of the arch of the skull, on a line with the nose, and, consequently, equidistant from both ears, is the sagittal suture, — taking its name from a fanciful resem- blance to an arrow, lying between the bow and string. There are several other sutures, but it is not very im- portant to be particular in their description. At birth the pieces composing the head, are small, and imperfectly formed. As we increase in growth, the bones also in- crease in circumference, till their edges finally meet and form the suture. ANATOMICAL CLASS BOOK. 1,5 When infants labor under a dropsy of the brain, the accumulation of water is often so great, that the head of the poor child is enormously enlarged. Such a vast col- lection could not be contained in the head, if the bones had been united. Being only slightly attached at differ- ent places, or, perhaps, not at all, the membranes on the inside, are put upon the stretch, and the bones offering no resistance,are actually pressed out of place. An enlarge- ment of the head never takes place, after the sutures are formed, though there may be a collection of water in the cavities of the brain. In preparing the skulls of animals for a cabinet, the mode of opening the seams or sutures, that the shape of each bone may be seen, it is usual to fill them with dry beans, perfectly full, and after having been placed in warm water, they swell and pry the whole apart. From infancy to the tenth and twelfth year, the sutures are imperfect; but from that time, to thirty-five and forty, they are distinctly marked; but in old age, they are near- ly obliterated. Blows should by no means be given children on the head, either by the hand, as in boxing the ears, or by sticks, ferrules, and the like relics of the old and obsolete mode of school-government. The entire character and destiny of a child may be altered by a rap on its half-formed skull. It is not only exceedingly dangerous, but criminal, to be instrumental in giving a blow that may produce such im- portant changes in the brain. THE BONES OF THE FACE. For the sake of order, these are separated in those constituting the upper and lower jaw. A minute descrip- tion of the thirteen bones of the upper jaw, would be fatigu- ing, and altogether unnecessary; yet some of the princi. 16 ANATOMICAL CLASS BOOK. pal characteristics of a few of them, will assist the student in obtaining a more exact knowledge of other parts. upper jaw bones. — Ossa maxillaria superior a. Many irregularly shaped small bones are united to the upper jaw, — as the palate, vomer, &c The upper jaw is in two pieces, on the arch of which are situated the teeth, in pits, called alveolar sockets, because they some- what resemble the cells of honeycomb. Just above the angles of the mouth a hard protuberance is felt, where the cheek bone is met by it, which is hollow. Nearly half an ounce of fluid is sometimes secreted in it, in cases of severe inflammation, arising from diseases of the teeth. Not unfrequently the roots of the eye-teeth protrude quite into it. The name of this cavity is antrum. Its use, in common with the one described in the os frontis, is to as- sist in strengthening the voice. cheek bones.— Ossa malarum. These stand between the last mentioned protuberance and the outer angle of the eye, contributing to the forma- tion of the orbits. bones of the nose. — Ossa nasi. Two bones, which are merely convex, slender pieces, about an inch in length, meeting in the middle, form an arch, which thus enables the nose to resist hard blows. The partition is one bone, vomer, so called from its re- semblance to a ploughshare. Sometimes it is twisted more towards one side than the other, — giving a crooked or one sided nose, which materially influences the ex- pression of the face. J5k Within each nostril, there are two distinct bones, called *r - turbinated, because rolled up like the folds of a turban ANATOMICAL CLASS BOOK. 17 but far more like a roll of parchment. They are thin and porous, and wound up in the manner we find them, to oc- cupy less room. On them is spread out the olfactory nerves, in the form of a gossamer-web. By this contriv- ance, surface is gained, without occupying too much space. The turbinated bones in a dog's, lion's, or tiger's nose, were it possible to spread them, would present a broad surface, it is supposed, equal to several square feet; — but by being rolled, like a scroll, they can be packed in the narrow canal of the nostril. Man, not being designed to be dependant, particularly on the sense of smelling, has small internal nasal bones:—quadrupeds, however, are wholly guided in the search and choice of food, by this sense ; hence the complicated apparatus, so much superi- or to our own. These turbinated bones are liable to dis- ease, and are the seat of tumors called polypus of the nose. tear bones. — Ossa Lachrymalia. There is one in each orbit, the size of the finger nail, — having a groove to conduct the tears into the nose. palate bones.— Ossa palatina. Quite on the back part of the roof of the mouth, these jut backward, towards the throat, having, in life, a cur- tain or valve suspended to them, which prevents fluids from rushing into the nose, in the act of drinking. Usual- ly, accompanying the misfortune of hare lip, these bones are wanting, — which accounts for the want of distinct articulate sounds, in such persons. lower jaw bone. — Os maxillare inferiora. All that is particularly interesting in this bone, will be discovered in the plate, in which a vast many muscles will 2* 18 ANATOMICAL CLASS BOOK. be seen, connected with it. There is a canal, the size of a knitting needle, running through it, from one angle to the other, traversed by a nerve that gives a twig to the fang of each tooth, as it passes along. An artery also makes the same circuit, supplying the teeth with blood. bone of the tongue. — Os hyoides. It is situated in the muscles of the neck, quite in the upper and back part of the throat ; its existence would hardly be suspected, were it not felt by pressing with the thumb and finger. Fig 6. y Explanations of Fig. 6. ■a b, merely indicates the places where the arms, or processes ot this bone, are united to the body, a, a, the arms. Its shape is much like the under jaw, or the letter U,— having the diameter of a dollar. Besides being the origin of the tongue, moving up and down, as the tongue is moved, it serves another important office, of keeping the mouth of the windpipe open, like a hoop in the mouth of a sac. bones of the ear. — Ossicula auditis. Each of these, the malleus, incus, stapes, and os orbicula- rr, are minutely described in the article on the sense of hearing. bones of the spine. — Vertebrae. Twenty-four bones, similar in shape, but varying in size, laid one above the other, are collectively called the spine. Processes, or arms, extend out on each side, on a line with the limbs; and one projecting backward, is the spinous vrocess, which gives the name to the whole chain. These ANATOMICAL CLASS BOOK. 19 points are the levers, by which the muscles move the whole, as a column. No one vertebra can be turned on its axis, but the entire series admit of a twisting movement, as demonstrated in all the attitudes which the body as- sumes. On the backside of the body of the blocks, the union of the three arms forms a ring, — and the twenty- four, present a canal, through which the spinal marrow passes down, giving off nerves between every two bones, to go to the ribs and muscles on the sides. FjV. 7. 24---- 23- Explanations of Fig. 7. This shows the connexion of the blocks or vertebrae, constituting the backbone, or spine. All the lines, indicat- ed by figures, from 1 to 24, indicate nerves, which come out between the bones, from the spinal marrow. Fig. 9 is the place of the stomach ; 20, 15 the liver; 24, the kidneys; 18, the spleen ; 23, the mem- 9 brane, around the border of 17 which, the intestines adhere ; 18 U and 12 is tho bone called 19 os sacrum, which, by being prolonged in quadrupeds, is 24 the tail. Man, being upright, 22 the bone is short, and curved, and thus holds up the organs, 10 which, by their weight, 13 would otherwise have a ten- dency to fall through the bot- tom of the pelvis. —11 12 20 ANATOMICAL CLASS BOOK. Those of the neck are less confined than those of the back or loins, in consequence of the processes being more horizontal; otherwise there would be an inability to car- ry the head towards either shoulder. Between these vertebrae, there is an intervening sub- stance exceedingly elastic, convexed on both sides,—be- ing thick in the centre, and thin at the edges, which are analogous to cushions, to prevent a sudden jar in our movements. These are the intervertebral substance, rath- er compressible, yet elastic. After being in an erect po- sition considerable time, the superincumbent weight presses them down thinner, — so that a person is shorter at night, after fatigue in walking, than in the morning, after the intervertebral pieces have restored themselves to their original condition. Explanations of Fig. 8. This is an accurate drawing of one of the bones of the spine, at the neck : a, is the body of the bone ; b, the spinous process, or handle, which gives the name of spine to the whole column; c, c, the trans- verse processes, to which the mus cles adhere, producing motion ; d, d, round holes through the arms of the bone, for safely lodging an ar- tery, which carries blood to the brain; e, e, the upper, and/./, the under surfaces, which make a joint with the blocks above and be- low it; g, the hole through which the spinal marrow, or pith of the back, passes, in safety from the head, through the whole chain of twenty-four vertebrae. A person becomes round shouldered, as the expression is, in consequence of the elasticity of the front edge of these pads being overcome. A permanent stoop or bend of the back is the result. Old age, also gradually weakens the elastic power, and therefore aged men are often crooked, infirm and shorter, than in their youth. Distortions of the body, producing deformity, are refera- ANATOMICAL CLASS BOOK. 21 ble to the want of spring, or proper elasticity in these cushions. The topmost of all the bones of the spine, is called the atlas, because it supports the head, as Atlas was fabled to support the globe. It is a ring of bone, without a body, which distinguishes it from all below it. With the skull, it forms a joint, allowing the head to move forward and backward, but in no other manner. Joining the atlas, is the dentatus, or tooth-like bone, having its name from the resemblance which a particular portion of it bears to a tooth. In a full grown man, the process is about half an inch high, above the body of the hone, — and smooth, jutting up into the atlas. Around thispift)t, the head rolls. If, by any sudden jerk, the head is thrown too violently back or forward, the dentatus, may be forced from its place, — which would be a dislocation, or breaking of the neck, in popular language. When criminals are executed by hanging, the process is common- ly torn from its place, presses on the spinal marrow, which, on its way down the back, passes by the side of it, and death immediately ensues. All the remaining twenty-two separate bones, of which the spine is constructed, are called, simply, vertebras. RIBS AND BONES OF THE CHEST — CvStt, showing them placed in two rows. This is a back view of the carpus of the right hand, a the boat shaped bone; b the half moon shaped ; c the wedge shaped; d the pea shaped; which make the up- per row, joining the fore arm. In the second row, are the four others, which are united, by a joint, to the palm of the hand. Their names are naviculare, lunare, cuneiforme, orbku- lore, trapezium, trapeziodes, magnum, and uneiforme. bones of the palm. — Metacarpus. A detailed account of the shape and size of the bones of the metacarpus, or palm, would seem to be unnecessary, as every person can ascertain their number and relations by feeling his own hands; the plan, however, is inserted. Fig. 16. Explanation of Fig. 16. Four metacarpal bones, side by side, precisely as they are placed, and of the true shape, forming the palm of the hand, are seen in this figure. The metacarpal bone of the thumb is seen in Fig. 17, marked a. ANATOMICAL CLASS BOOK. 20 Fig. 17 Explanation of Fig. 17. There are but three bones in the thumb, which are larger than those in the fingers, because it was designed to oppose them, and therefore possesses a structure quite different. To these three, five mus- cles are attached, a, b, c, are the three, but it should be recollected that a really belongs to the meta- carpus, so that the phalanges of the thumb are two. Only two bones exist in the thumb, but there are three in each finger, —collectively called phalanges, being four- teen in number. Fig. 18. Explanation of Fig. 18. Twelve bones, as exhibited in this plan, constitute the fingers of one hand. They are separated from each other, that the exact form of the extremities of each may be seen, a the first bone of the litte finger, 6 the second, c the third: the same letters point out the three, also, composing the index, or fore finger. b _. 3* 30 ANATOMICAL CLASS BOOK, Fig. 19- Explanation of Fig. 19. Here is presented a back view of all the bones of the hand, as they are connected with the eight little bones of the wrist. Each bone is so distinct- ly represented, that a very young child may understand the arrangement. Explanation of Fig. 20. All the bones of the arm, fore arm and hand, are here exhibited in connex- ion, with reference to impressing it on the mind, after hav- ing read a short des- cription of the indi- vidual parts of the upper extremity, a is the head of the arm bone, articulated to the shoulder; 6 the jojnt or elbow, form- ed by the ulna and lower end of the arm; c the shafl of the os humeri or arm; d the radius or handle of the hand, united, solely, to the wrist; e the ulna, which alone forms with the arm, the joint. ANATOMICAL CLASS BOOK. 31 BONES OF THE INFERIOR EXTREMITIES.-- Ossa Fcmoris. First, the os femoris, or thigh bone, is the largest and longest in the skeleton : indeed it needs to be, as it sus- tains the entire weight of the whole body. The ball, by which it is articulated in the deep socket of the hip bone, appears to be at the end of a branch, standing out at a considerable angle from the shaft, as seen in the engraving of the skeleton. This is the neck of the fcmoris. Its lower end or condyle, is quite large, to make a part of the knee joint. All the muscles assisting in running, walk- ing, or dancing, are variously connected with it. BONES OF THE LEG. — Tibia. Tibia is the scientific name of the shin bone, because it was thought to look like a pipe. United with the con- dyle of the thigh bone, assisted only by the knee pan, the knee joint is formed. At the ankle, it is admirably fitted to the astragalus, to permit flexion and extension of the foot, as in walking. A piece or splint, called maleolar process, slides down by the side of the joint, to increase its strength. The pro- cess may be felt, being under the skin like a knob, on the inner side of the ankle. This joint is very securely arranged, to prevent luxa- tions : as it merely moves in two directions, backward and forward, — nothing short of a degree of violence that in- jures the bones, can materially affect it. Beside its lig- aments, the tendons of many muscles contribute to its security, strength and perfection. 32 ANATOMICAL CLASS BOOK. Fig. 21. 4 3 3 5 2 7 6 Explanation of Fig. 21. These three plans show how the two bones of the leg are united above the ankle joint— 1, 2, 3, 4, 5, 7, 7, 6 — mark the ligaments which bind them so firmly. Outside of the tibia, is a long, slender bone, the fibula, lying on the side of the head of the tibia, but having nothing to do with the knee joint; — it passes down past the ankle joint, giving the same security to it, that is af- forded by the maleolar process of the tibia, on the inside. Between the two bones, all the muscles, and they are numerous, arise, which go to the foot and toes. BONES OF THE INSTEP Ossa Tarsi. Five bones are found in the tarsus or instep, one of which is nearly all given to the heel. An arch is formed by the other four, similar to the wrist, giving a convexity ANATOMICAL CLASS BOOK. 33 Explanation of Fig. 22. By this diagram, the skeleton of the foot will be clearly under- stood, even without the aid of the bones. Twenty-six bones are here so curiously grouped together, that an arch is made between the heel and ball of the great toe : — a, shows the five bones of the metatarsus ; d, e,f, g, and h point out the five bonesof the instep or tarsus ; and b, c, and t, indicate the phalanges or toes. to the top of the foot. On the under side, in the sole of the foot, all the flexor muscles of the toes are found. This structure conduces to the elasticity of the step, and the weight of the body is transmitted to the ground by the spring of the arch, in a way to prevent the injury of nu- merous organs, by a sudden jar. Each one of them has a specific name, viz. os calcis, the heel; astragalus, being part of the ankle joint, named from its likeness to a block used by the Greeks, in playing a game of chance ; cuboides, or square bone ; naviculare, the boat shaped ; and cunei- forme, or the wedge shaped bone. As in the hand, between the instep and toes, is the metatarsus, in which are five bones, placed like the sticks of a fan, to be articulated with the first row of the bones of the toes. Precisely as the short blocks of bones are arranged in the thumb, so they are in the great toe, being, however, proportionably larger. There are two in this and three 34 ANATOMICAL CLASS BOOK. in each of the four remaining toes, —the whole of which are phalanges, being fourteen in all. Fig. 2^. Explanation of Fig. 23. This represents the bones of one toe, as they stand, in relation to each other — a the metatarsal part, concealed in the muscles, and bed, the three phalanges. Fig. 24 is the skeleton of the great toe: o the metatarsal por- tion, and b c the phalanges. Sesamoid bones, considerably larger than in the thumb, are discoverable on the under side of the first joint of the large toe. skin of the bones.—Periosteum. Over every bone is a thin, white covering, the perioste- um, closely investing it. Its use is to conduct the nutri- cious vessels and nerves into the substance of the bone. It serves also for the attachment of the muscles, whicn could not otherwise be fastened to the smooth surface. Though apparently insensible, it is amply furnished with nerves, arteries, and veins, but its vitality is very low. ANATOMICAL CLASS BOOK. 35 growth of the bones ; — or Osteogeny. By this term, is understood the doctrine of the formation and growth of the bones. From infancy, till the age of about twenty years, they are constantly undergoing changes. In fact, they are completely renewed, many times in the course of a long life. No particle of matter can long re- main at rest in a living system. When one portion is re- moved, another is put in its place, so that by the circula- tion of the blood, the greatest activity prevails, even among these earthy portions of the body. The arteries, hereafter to be described, are the arti- zans, — carrying whatever is necessary to promote the growth, or to repair the wastes of the system. They also fashion each organ, give shape to every bone, and sustain and furnish them with vitality. Bones have nerves, but they are small, and only con- nect them with the other more highly organized parts. When they are diseased, they become painful as the-mus- cles ; but in health, they are insensible. As a whole, the skeleton is merely a frame, on which are suspended, or attached, all the organs of motion. It is full of joints — and each bone is a lever, to be acted upon by the power of a muscle. This, which in most of the large animals is in the centre, in many of the smaller tribes, is on the outside, in the form of a shell. Examples may be found in the turtle and lobster, beetles, &c. Such a remarkable piece of mechanism as the skeleton, divested of a thousand important, wonder-working accom- paniments, exhibits in the clearest light, the goodness and wisdom of God. The fashion of each bone, and above all, the skilful and nice adjustment of the whole, and their subserviency to the different fibres and tubes which are intimately connected with this complicated, yet perfect piece of architecture, must strike a reflecting mind, most 36 ANATOMICAL CLASS BOOK. forcibly, that the evidences of the existence of a Supreme Power, are here manifested in a most extraordinary manner. DIFFERENCES BETWEEN MALE AND FEMALE SKELETONS. Were it true that men have a deficient number of ribs, there would be no difficulty in designating the skeletons of different sexes. To an inexperienced eye, it will al- ways be a nice point, to determine one from the other. The skeleton of the male is larger aad heavier than that of the female. The surfaces of the bones are rougher, as the muscles which moved them were more strongly de- veloped, and capable of exerting more power than those of the other. The head of the female, on an average, is smaller than the male ; the sutures are less notched ; and the cavities in the bone of the forehead, and upper jaw bones, are considerably smaller. All the limbs are more delicately and slenderly formed. Processes are less prom- inent, and depressions are comparatively more superficial. A still stronger difference, however, is found in the pel- vis,— a kind of arch, or bony circle, bounded by the hip bones. In females, the pelvis is much broader than in men, and the hips are spread more outwardly. Lastly, the necks of the thighbones are longer, — giving them the appearance of being particularly broad across the hips: thus far, only, females are constructed, in the frames of their bodies, to differ very essentially from the male. The breadth of the pelvis, in connexion with the peculi- arity of a long neck to the thigh bones, brings the knees nearer together. If two skeletons, one of a man, the other of a woman, are suspended, it will be noticed that the lower extreme- ties of the male would be nearly parallel to each other; whereas, in the other, the knees will approximate so near- ANATOMICAL CLASS BOOK. 37 ly, as to touch. Another difference consists in the capa- city of the chest: one is small, and the other is large. The bones of the feet and hands are large in men ; — but in the female they are slender, smooth and delicate. Fi- nally, the height and weight would have an influence up- on our judgment in deciding upon the character of either. DISTORTIONS TO WHICH THE BONES ARE LIABLE. Many injuries of the bones are induced by the careless- ness of nurses, in infancy and the first years of childhood, which have a permanent influence on the figure and health in after life. Females, especially, by the caprice of fash- ion, are the subjects of many alarming diseases, arising from distortions of the bones. One of the most serious affections, a distortion of the spine, is muchoftener found in females, than in males. Boys generally lead an active life, — enjoying a free exercise of all their limbs, in various youthful pastimes. Girls, by a perverse custom, are taught that they were made for the house, and not for the open air. Their employments are therefore com- monly of a sedentary kind, necessarily confining them to one posture many hours at a time. Added to this, which is enough to enfeeble any constitution, their bodies are compressed by the modern modes of dressing, to such a degree, that instead of naturally expanding, to give full play to the lungs, the chest is kept from enlarging its capacity, by stays, and closely fitted dresses. The ribs are pressed inwardly, the spine prevented from having motion ; the lungs cramped, and consumptions, inflamma- tions, and other oftentimes incurable maladies, are the certain results. Notwithstanding the odium cast upon the Chinese for their ridiculous fancy for the small feet of their females, which are prevented from growing, by being compressed 4 38 ANATOMICAL CLASS BOOK. in iron shoes, it is not so cruel nor absurd, as the practice among the females of all civilized countries, at the present day, of preventing the growth of the waist. Physicians, philanthropists and philosophers, have each exerted themselves, to awaken an interest, — to arouse females to a sense of their danger, but it has been to little purpose. Though seriously deformed, they cannot be persuaded to abandon a custom, which, in their apprehen- sion, improves their otherwise beautiful forms. We here introduce the following drawings, to show what is the actual condition, of the chest that has become permanently diminished by artificial means, compared with one that has been developed as nature intended. Young ladies require nearly as much exercise as boys, but of a less violent character, as their physical organiza- tion is not calculated, it is reasonable to suppose, for se- vere exertions of the muscles. They certainly require loose, easy clothing, that the bones concerned in the forma- tion of the apartment in which is placed the vital ap- paratus, may be free, unimpeded, and unrestrained. Contracted chest. An outline is here presented of the chest of a female, to show the actual condition of the bones, as they appear after death, in every lady who has habitually worn stays. All the false ribs, from the lower end of the breast bone, are unnaturally cramped inwardly towards the spine, so that the liver, stomach and other di- gestive organs in the immediate vicini- ty, are pressed into such small compass, that their functions are interrupted, and in fact, all the vessels, bones, and viscera, on which the individ- ual is constantly depending for health, are more or less distorted and-enfeebled. Whatever has a tendency to confine those parts of the frame which were designed for motion, positively tends to ANATOMICAL CLASS BOOK. 39 Skeleton of a well formed female chest. By comparing the accompanying plan of a well developed and natur- ally proportioned female chest, with the frightful skeleton appended to the preceding note, the difference is strikingly apparent Here is breadth, — space for the lungs to act in ; and the short ribs are thrown outwardly, instead of being curved and twisted down towards the spine, by which ample space is afforded for the free action of all those or- gans, which in the other frame, were too small to sustain life. The first may be regarded as the exact shape and figure of a short lived female ; and this may be contemplated as an equally true model of the frame of another, who, so far as life depends upon a well-formed body, would live to a good oJd age. the production of disease ; it is therefore of the highest interest to the well being of our species, that an elementa- ry knowledge of the structure of the human body should be taught, and everywhere understood, — that precautions may be taken to avoid a threatening danger. Physical ed- ucation is not only loo much neglected, but what is still more lamentable, scarcely appreciated in this country. If parents, in the first place, and instructers in the second, studied more the education of the body, the intellectual faculties would be more fully, and energetically developed. Above all, the young should be instructed correctly, in the knowledge of the laws of animal life. The lungs too suffer, — and in those cases, which are ninety in a hundred, where the stays have been laced on in very early life, before the ribs have become perfectly ossified, the chest is never developed; — it never assumes the form which it would have had, were it not for this mechanical restraint; consequently, for want of capacity, or in other words, for the want of room, the lungs are too 40 ANATOMICAL CLASS BOOK. small for the requirements of the body ;■— they cannot oxygenate the blood, — an indispensable vital process. Corset boards are quite as reprehensible, though the in- juries to which they give rise, are less apparent in the be- ginning. The busk operates almost exclusively on the sternum or breast bone, which is easily bent out of its original position, at its lower extremity. By a constant pressure of an inelastic board, the lower end of the sternum, which juts down into the abdominal muscles two or three inches, is forced inward, and be- coming ossified in that direction, is productive of serious injury to the stomach, which lies just behind it. A multitude of painful and protracted diseases, by which females in the higher walks of society, in this age, are hurried to an early grave, have their origin in this hor- rible custom of wearing stays. Thousands upon thou- sands of young ladies are the yearly victims, even in the United States, to consumption, which is wholly referable to this fashionable, but perverted taste, of conforming to a practice which has for its object, the improvement of the female form ; as though the Creator, in constructing the most beautiful work of his creation, neglected to give that last finishing process, which they imagine them- selves to have discovered, and which can alone be satisfac- tory to the sex. While we lament the tolerance of an evil in our coun- try that sweeps the young, the beautiful, and the intelligent to the tomb, before the summer of life has fairly commenc- ed, we scarcely indulge the hope of a reformation : per- nicious customs which are preserved by common consent, cannot be easily overcome by persuasion or argument. If, notwithstanding the many illustrations given of the sad effects of stays and busks, by various philanthropic writers, mothers and nurses manifest no disposition to be ANATOMICAL CLASS BOOK. 41 influenced by their opinions and advice, the duty most certainly devolves on all public teachers, in a delicate and appropriate manner, to instruct their pupils in the first principles of preserving health, by explaining the morbid effects which arise from confining the body in stays. One of the first lessons in physical education should be, to strip from the pupil every unnecessary artificial restraint upon the body and limbs. TEETH. In manhood, there are thirty-two teeth, divided in the following manner : 8 Incisores, — or cutting teeth. 4 Cuspidati,—or dog shaped, — being pointed. 8 Dicuspides, —or two pointed double teeth. 8 Molares, — or grinding teeth. 4 Dcntes Sapientiae, — or wisdom teeth. The first set, or milk teeth, are twenty in number, ap- pearing from time to time, from the age of about ten months, to three years, when they are all developed. There are, however, many variations as respects the peri- od of cutting them, depending on constitutional causes. When the roots are absorbed, the tops fall off from the gums, and the second set are protruded. The jaws, in the mean time, become longer and broader, which allows room for an increased number, of a greater size. In the centre of each tooth, is a cavity, in which the pulp of a nerve lies, and which is the seat of pain, when the oody of the tooth is so decayed as to expose it to the air, or bring it in contact with food. Each root is also hollow, allowing the fibre of a nerve to communicate with the nerves of the jaw, and blood vessels also run in by the side of it, to nourish the whole. The enamel is the outside, hard crust, which gives the requisite finish to the tooth, and renders it strong enough 4* 42 ANATOMICAL CLASS BOOK. for mastication. This enamel is much thinner on the teeth of some persons than on others, and scaling off, the bony part of the teeth being exposed, soon falls into disease by the contact and influence of various kinds of food, drink, heat and colds. Acids of all kinds are particularly injurious to the teeth, because they act chemically on the lime contained in the enamel, — destroying the connexion of the particles, and thus, ultimately, exposing the nerve. Hot drinks are also pernicious. Individuals living on moderately cool food, and drinking cold water, simply, preserve their teeth in all their origi- nal beauty and goodness, to an advanced period. Sugar is not destructive to the teeth, as generally sup- posed : slaves, on sugar plantations, possess the finest sets, uninjured, apparently to extreme old age. Cold water only is advisable, applied with a soft brush, for keeping them white, clean and in a healthful condition. The various dentifrices, salt, ashes, charcoal, &c, actually injure them by attrition in the application, and should never, therefore, be used. Chewing and smoking tobacco, is very destructive to the teeth. To youth these few prac- tical considerations are worth their recollection. When the teeth are all extracted, the sockets which sup- ported them are absorbed, and hence the jaws are nar- rower, which explains the reason why, in old age, the mouth is smaller and the lips sunken : it also accounts for the difficulty with which words are articulated. The tongue being compressed, moves with less freedom, and distinct enunciation becomes extremely difficult. ANATOMICAL CLASS BOOK. 43 QUESTIONS What is understood by Anatomy? What is Comparative Anatomy and its use ? Into how many parts is the science divided ? What is Osteology ? What is Syndesmology ? What is Myology ? What is Bursology ? What is Angiology ? What is Adenology ? What is Splanchnology ? What is Hygrology? How are the bones classed ? How are the names of bones derived ? Are they hollow or solid ? What are processes and their use ? What is a natural skeleton ? What is an artificial skeleton ? How many bones compose the skeleton ? How is the skeleton divided by anatomists ? How many bones compose the skull ? How manv are there in the face ? How many teeth and how arranged ? Has the tongue any bone ? Is the sense of heaiing dependent upon bones? How many bones compose the trunk ? What are Sutures ? Where is the Coronal Suture? * How does the male differ essentially from the female skele- ton? 44 ANATOMICAL CLASS BOOK. Why are some bones hollow ? What is the use of marrow ? How many bones in the fore arm ? How many in the wrist ? What is the carpus ? Where is the metacarpus ? How many phalanges in the fingers ? How many bones in the foot ? Are extra bones ever found — and if so, where ? How are bones said to be united ? Where is the os frontis ? Of what use are the cavities in the bones of the forehead and cheeks ? Where is the occipital bone situated ? What circumstance renders the temporal bone particu- larly interesting ? What do you understand by the spine ? Why are persons taller in the morning than at night ? Why are aged persons inclined to be crooked, and shorter than in their youth ? How many ribs are there ? What is meant by pronation of the hand ? What by supination ? What is the use of the periosteum? What is osteogeny ? Have bones any sensibility ? How do they grow, or how are they repaired when injured ? What is the use of the skeleton ? What is the metatarsus ? What are ligaments ? How many bones in the arm ? How many teeth in adults ? Where is the sternum ? What is the use of the clavicle ? How many bones in the foot ? Of what use is a bone in the tongue ? Are there more ribs in a male than in a female skeleton ? ANATOMICAL CLASS BOOK 45 LIGAMENTS. OR SYNDESMOLOGY. In the economy of the system, the skeleton would have been in a very imperfect condition, if so many bones were not firmly connected together. The bands and straps which so effectually and strongly connect them, one with another, are called ligaments, and syndesmology is the study or doctrine of them. Such is the prodigious tenacity of the ligaments, that the bones are sometimes fractured, before they are torn from their points of adhesion. Ligaments, like the bones themselves, are nearly insen- sible, white and shining, and commonly short, thin and tough. Where the ends of two bones meet, as in the con- struction of a joint, their situation is maintained by liga- ments running from one to the other. Possessing but a very slight degree of elasticity, the joints do not become loose or shackling, unless extension is maintained a very long time. Were it not for ligaments, the bones of our bodies would fall down by their own weight. A natural skeleton is one on which they have been preserved, with reference to showing the precise connexion of the bones. Some ligaments are exceedingly interesting, from the 46 ANATOMICAL CLASS BOOK. Fig. 27. Explanation of Fig. 27. e, d, are the crucials or cross liga- ments, so remarkable in structure and office ; /, the tendon of an extensor muscle; c, the head of the fibula, joining the side of the shin bone; a, the articulating surface of the lower end of the thigh bone, covered by the knee pan ; b, refers to the broad liga- ment, turned down from the joint to expose the cross ligaments, having the knee pan on it. circumstance that they keep a joint from bending the wrong way. The knee would be the weakest, and most liable to get out of order, of any, were it not for its nume- rous ligaments. Within this joint, two ligaments are so arranged, that they cross each other, like the legs of a saw-horse, com- pletely preventing the leg from being carried too far back- ward or forward. The lateral ligaments guard against dis- locations on either side. One single round ligament fastened on the head of the thigh bone, ties it into the centre of its socket, keeping it always in place, however much the limb be moved in opposite directions. Ligaments exist wherever two bones meet at their ex- tremities, and also abound in the cavities of the body, in the form of flat or round cords, to sustain the weight of important organs, as the liver, spleen, and pancreas. Without these supports the liver would inevitably fall down, from its place just under and behind the false ribs of the right side, upon the hollow organs below. The ANATOMICAL CLASS BOOK. 47 Fig. 28. Explanation of Fig. 28. Complex as the ligaments appear in this plan, there is certainly an admirable simplicity, conducing ex- actly to the perfection of the frame of the hand. Each letter, as in other diagrams, shows the place of each individual ligament, as found on dissection, joined to the bones, which are thus drawn together like so many wtdges. It would be utterly impossible for the most in- genious mechanic to take the dry bones and secure them together by wires, clasps, rivets or straps, so strongly as nature has done by means of these little shining ligaments. gall-bladder is tied to the liver by a ligament; the intes- tines are kept in their places by ligaments ; — the stomach, too, without ligaments would soon be thrown by its own muscular exertions, during digestion, from its natural lo- cality. Even in the skull, ligaments assuming various forms, support the lobes of the brain, protect vessels, and give strength to the architecture of the head during the first years of life. Indeed, ligaments are indispensable throughout the animal frame. By means of them, the small bones of the foot are kept firmly together in the shape of an arch, in the instep : — otherwise the weight of the body, in the exercise of walk- ing, would crush them apart, and forever destroy their curious connexion. 48 ANATOMICAL CLASS BOOK. Fig. 20. Explanation of Fig. 29. By this drawing, which is true to s nature, it will be seen, distinctly, how the bones of the instep and ankle, are articulated ; —how the instep and pha- langes or toe bones meet; and lastly, the small letters direct the eye to the locality of each ligament, which assists in binding this congeries of large and small blocks firmly together, Tike a pavement. g In cases of club-foot, the ligaments are very much deranged, in conse- quence of the distortion and displace- ment of the bones. But, however for- midable the case may appear, if season- able exertion is made, the very worst club-foot may be re-modelled by an iron shoe, provided with metallic rods run- ning up by the sides of the ankle, so that both the apparatus and bones may be kept in place. Without the odvice of a surgeon, any ingenious mechanic can remedy a malformation of the toot, if the trial is commenced while the bones are imperfectly ossified. By ligaments the wrist is fastened to the arm, indepen- pendently of muscles; the shoulder to the shoulder blade; — the head to the first bone of the neck ; — the ribs to the spine, and the vertebrae to each other. The office, there- fore, which these deep seated, almost unnoticed straps hold, in binding the whole frame together, cannot be overlooked by any one who contemplates the marvellous work of God, as exhibited in our own complex, yet beau- tifully fashioned bodies. ANATOMICAL CLASS BOOK. Fig. 30. Explanation of Fig. 30. Having completed a general description of all the individual bones, and exhibited some of the principal ligaments of the limbs, the object of this third drawing of an entire skeleton, is first, to give aside view of the parts adverted to in the foregoing pages, -- without letters or references to deface the engraving, or to perplex the mind, The peculiar attitude of the figure was given it by the artist, merely be- cause a larger sized drawing could thus be given in a little space. 5 50 ANATOMICAL CLASS BOOB. THE MUSCLES. OR MYOLOGY. An interesting department of anatomy is called myology, or the doctrine of the muscles. We would by no means surfeit our young readers with the consideration of subjects which are only considered valuable to the anatomist: — but we wish general inquirers to participate in some of those sublime manifestations of the all-creative Power, presented in the mechanism of animal bodies, which have too long been locked up in libraries. All that pertains to anatomy, either human or compara- tive, possesses the highest degree of interest. We are not so enthusiastic as to suppose that every body can be induced to feel so earnestly devoted to this science as ourselves; — nor is the desire entertained of making dry bones a fashionable topic of general conversa- tion ; but we do most fervently hope that the leading principles of anatomical and physiological knowledge will be diffused ; will yet be taught in all the schools of this country. The advantages to youth, arising from a public dissemi- nation of these sciences, will be very numerous, as it will lead the young to correct views: — it will dispel that vulgar kind of mystery in which the functions of individual organs are enveloped : — it will strengthen the morals, elevate the mind, and finally, be one of the surest means of fixing the attention to the considerations of the char- acter and Omnipotence of God. ANATOMICAL CLASS BOOK. 51 Ordinarily, there is more vulgar curiosity, seeking to be gratified on a variety of topics, embraced in these valuable sciences, than in almost any other. Next to the insane expectation of converting the base metals into gold ;— the desire and the hope to prolong the period of life, to raise the dead, and to avert disease, has always been founded on a limited and false knowledge of anato- my. Those who are truly learned in the science, dis- cover the impossibility of maintaining never failing youth : they are convinced of the necessity of death, the only means of allowing a succession of beings; — the only means by which matter can assume the forms that insure this unfailing result. Our bodies are indeed marvellously constructed ; the materials of which they are composed, possess the most opposite characters, — and the effects produced by the harmonious operation of each fibre, however minute or remote, contributes something towards the perfec- tion of the whole. The moving powers, the self-acting levers, and the invisible something which guides the movement, or limits the duration of action, belong to another inquiry ; yet, before arriving there, it is first necessary to investigate the instruments of motion, the muscles. MUSCLES. There are 527 muscles in man, 257 being in pairs. Wherever there is a joint to be flexed, a bone to be moved, or a motion of any kind to be effected, it is entirely executed by muscles. Muscles are, in popular language, flesh; but instead of being an irregular mass, as too com- monly supposed, exact order is maintained; a certain number of threads are invariably deposited, with syste. matic attachments, with reference to a specific kind of motion. 52 ANATOMICAL CLASS BOOK. Chance has nothing to do with the muscular tissues. Each muscle is formed by an exact rule, from which nature never departs, without exhibiting a monster, whose motions are so far a deviation from the species, that the individual is physically defective, and incapable of transmiting it to its offspring. A majority of the cases in which too many or too few organs are seen, are to be im- puted to incidental causes, which prevented nature from completing those portions, the absence or excess of which constitutes the essential characteristics of a species. The laws of the animal economy are immutable. The figures of the muscles are as various as possible, some being round, others square, triangular, or flat like a ribbon. In length too, the variations are remarkable. Belonging to the vocal box, the (larynx,) the muscles, opening and closing the rima glotidis, to vary the strength of voice, are only about an eighth of an inch : the sar- torius, or tailor's muscle, by which the legs are crossed, arises on the top of the hip bone, and extends six inches below the knee, passing two joints,— being nearly three feet long. On the back, the laiissimus dorsi, by which the hand is brought downward and backward, as by a blacksmith in using a hammer, is a foot broad on the back, scarcely an inch in width at its attachment to the arm, below the shoulder, but all of two feet in length. All muscles, are large in the middle, but small at the extremities : —each one, too, is enveloped in a sheath, to keep it separate from a contiguous one, that the action may not interfere with the assigned office of any other. Indeed, each bundle of fibres of which the muscle is com- posed, is secured in a sheath of its own, and the whole are finally encased in the outside tissue, that binds down and secures the whole. These coverings of the muscles are elastic, stretching ANATOMICAL CL*33 BOOK. 53 and recovering their original form when the contents are relaxed. When the greatest degree of contraction takes place, as in the muscles of the thigh, the power of the muscle is increased a hundred fold by the tightness of the fascia. On the arm, for example, between the elbow and shoulder, the flexor of the fore arm, in a state of action, produces a very prominent ball near the middle of the bone: on the inferior extremities, were the muscles to project out in such a manner, all symmetry would inevi- tably be sacrificed, and the power too, would be very much abridged. Laborers bind a cord round the arm when they wish to exert an extraordinary degree of strength : — sailors, too, in order to increase their muscu- lar power, usually wear a tightly girded leather belt just above the hips, — the principle of which is to bind down the bellies of the muscles, more closely than the straps which nature has placed over them. The muscles are divided into two classes, viz : the vol- untary, and involuntary; the first are subservient to the will; but the second order is wholly beyond its influence. To put the voluntary muscles in action, we have only to will it; to incline the power to effect an orderly contrac- tion. It is only necessary to will the bending of a finger, and it is done — to will the clenching of the hand, and the action follows instantly ; to flex the leg, or extend the foot, and the command of the brain is obeyed. On the other hand, the muscular fibres of the stomach are independent of the mind: the ear receives sonorous rays, and propagates them to the labyrinth, by the com- bined muscular apparatus within, nor can we prevent it by any effort of the mind to the contrary. Before muscles become orderly — before they can serve the mind, they must be taught. Thus the child is obliged 5» 54 ANATOMICAL CLASS BOOK to totter round the room, receiving severe falls, before the muscles become trained to the business for which they were designed. The infant that has crept, feels safer on its hands and knees, than on its feet, because, by prac- tice, the locomotive muscles obey the child in that posi- tion, and it is conscious of its security, from its recollection of the fact. When the child first endeavors to maintain an erect posture, its step is insecure, the muscles not having been associated to act in the new trial; the positive influ- ence of mind, therefore, must not be suspended an in- stant ; if it is, the infant falls to the floor. When, therefore, any number of muscles have had practice in any particular mode or time, a habit is ulti- mately established, enabling them to continue the accus- tomed motion, without the watchful efforts of the mind. It is in this way that we learn to walk, to articulate words, to rise, to sit, or assume a daily multitude of positions. The principal difficulty the young musician has to en- counter in learning to play an instrument, consists in teaching the muscles of the fingers to move as rapidly aa the notes are presented by the brain. Hence the long practice required, before rapid execution is attained. By a long course of schooling, the player can at length partially withdraw the mental superintendence,— he can slumber or abstract his thoughts from the air, or enter into conver- sation, but the fingers continue their unerring course in time and with surprising accuracy. The most opposite, and apparently incongruous associ- ations of muscular action, are exhibited by rope-dancers, in throwing carving-knives, which fall in a perfect line| points downward, toward the crown of the head, while heavy brass rings are whirled with extreme rapidity in op- posite directions, on each of the great toes. Such exam- ples of the extraordinary feats that may be accomplished ANATOMICAL CLASS BOOK. 55 by teaching muscles to act differently from what they ap- pear to have been expressly intended, are exceedingly common, but not the less surprising. It must not be lost sight of that the two orders of mus- cles are obedient to their proper rulers; the one being under the express dominion of the mind, and the other influenced only by its appropriate stimulus. Food is the natural excitant of the muscular tissue of the stomach, and the blood, by its presence, stimulates the fibres of the heart. But the most perplexing circumstance in relation to the muscles, is the property of contraction. Every mus- cle in the body is always tense ; relaxation is a misapplied expression, if it were understood that the rest of the muscle is like a rope slacked till it becomes pendulous between two points of attachment. However much a joint may he bent, the muscles always remain tense; ap- parently as much so, as when actually put upon the stretch by the extension of the same joint. They carry their contraction still further in cases of luxations. When the hip joint is dislocated, the muscles of the thigh, finding nothing to oppose them, shorten the limb by inches, and hold their grasp so tenaciously that pulleys are required to overcome their unrestrained, unauthorized activity. When the joint has been too long neglected, and the head of the bone cannot be carried back to the socket, on account of the violent rigidity of the surrounding muscles, they invariably continue in that condition through life. Such a limb is consequently thicker than its fellow, the circumference being gained at the expense of its length. Muscles are never weary — no, never, under any cir- cumstances whatever ; if that were possible, there would be examples of their inability to answer the requirements of the will, from this cause. The mind's control over 56 ANATOMICAL CLASS BOOK. them may be suspended or even lost, as will be shown directly, but still they are always active, and always in a state of contraction. If their irritability were reduced by fatigue, it could not be recalled ; the vis insita, the life of the muscle, survives the departure of the soul, and keeps it in a moderate contraction long after the vital tem- perature has been lost. Nothing, indeed, short of putrefaction, destroys its con- tractility. Death, by which is meant the separation of the spiritual essence from the material body, does not destroy, suddenly, the life of the flesh, as that survives for days and even weeks. The truth of this position is established by the application of galvanism to the bodies of malefactors — the rolling eye-balls, the cramped limbs, the heaving chest, and in the fiendish expression of the muscles of the face. An illustration of the permanency of this irritability may be seen also in the quivering meat hung up in the Bhambles of the market; it is exhibited in the writhings of the eel deprived of its head and its skin ; and in the violent snapping of the tortoise's jaws, many days after decapitation. When we are perfectly exhausted, by reason of long continued fatigue, the muscles are not the sufferers ; they then show their activity by violent exertions. Cramps, severe paroxysms, and painful contractions, at such times supervene, and rarely at any other. These arise from the loss of the nervous power, which is the regulator of the system. That power may be diminished by long continued ex- ercise, by extreme watchfulness, or by many other causes. Yet while it is feeble, the muscles twitch, and permanent distortions ensue, if the nerves do not recover their ener- gy. We retire to our beds, not to give the muscles an opportunity of reposing, but to recover nervous influence. ANATOMICAL CLASS BOOK. 57 Every muscle has an antagonist, with a few exceptions. Where there is one to draw in one direction, there is an opponent to counteract; by this contrivance, a complete freedom of motion is given to the extremities. Each flexor has, opposed to it, an extensor ; and the contraction of one, is partially accomplished by the relaxation of the other ; but the simultaneous action of both, fixes the part on which they exert their power ; thus, the flexors on the fore part of the neck, and their antagonists on the back side, maintain the head in a vertical line with the body. Each muscle terminates in a hard, white cord, appa- rently the compressed threads constituting its volume, al- though such is not the fact. These are called tendons. At the place of origin, the tendon is thin, inelastic, and short, soon intermingling itself with the substance of the muscle ; but at the other end it assumes another form, being either round, or delicately smooth, tape-like and narrow. This is the part which passes over a joint to be- come attached to the next bone. Tendons are nearly in- sensible, being so far removed from the ordinary sensibil- ity of everything else, that they rarely participate in the diseases to which all the soft portions of the frame are subject. To obviate friction, and prevent interference with its neighbors, each tendon is invariably conducted through a sheath, in which there is a copious secretion of a fluid, resembling oil, that keeps the cord soft, that it may glide easily. Symmetry of form is wholly referable to the tendons. Without them, the exceeding bulk of the muscle would produce, according to our present notion of the beautiful, the most hideous deformities. Were the muscles of the fore arm carried to the palm, of the same size that they have at the elbow, the wrist 63 ANATOMICAL CLASS BOOK. would be the diameter of the elbow— rendering the hand unwieldy and nearly useless. To the free circulation of the blood into its inmost re- cesse" the muscle is indebted for its vigor; and to the nerves'," • that sensitiveness which renders it susceptible ofpainftf. c>V'pleasurable sensations. In its institution, however, the muscle possesses a sensibili' , completely beyond the control of any nerves in the body ; a curious circumstance indeed, referred to in speaking of its vis insita. An exhibition of this proper- ty— this disposition to recoil under excitement; to remove itself from the contact of foreign substances ; in short, to preserve itself from the destructive agency of whatever has a tendency to exhaust its latent irritability, is within common reach. A demonstration of this phenomenon may be witnessed in the hearts of reptiles, pulsating by the prick of a pin, long after being removed from the ani- mal ; in the motion of the intestines of cats and dogs, cut into strips. While the vital temperature remains, they move like earth-worms, and when they have ceased to move, their irritability can be roused again by the applica- tion of stimuli. Here, then, is exemplified the existence of a property, purely vital, which never was, and in the instance before us, could not he influenced by the nervous system. Removed as this property is, from the direct influence of the nerves, it becomes, under peculiar circumstances, the only hope. In cases of suspended animation, as in drowning, swooning, &,c, there is a prostration 'of the nervous system —it cannot act — the will cannot produce an impression on the muscles, because its messengers, the nerves, are no longer in a condition, from some unknown cause, to transmit the orders. At this juncture, if no saving efforts are made, the individual dies. But a skib ANATOMICAL CLASS BOOK. 59 ful application of agents to the muscles, raises their tone to that high degree of excitability, that they actually re- suscitate the expiring spirit of the nerves. The instant that is effected, the sign of success is manifest i by the obedience of the muscles; the poor suffer'" .oves a limb, because he determines it; order is at tl.. .ame in- stant restored in the nerves, and the suffere- '.<•, restored to life, and his weeping friends to happiness. A CATALOGUE OF THE PRINCIPAL MUSCLES. Perhaps it may be thought that the following table is not only unnecessarily minute, but altogether too techni- cal ; but as we could devise no method of rendering it much more simple, without making the whole unintelligi- ble,— the scientific names of the points of origin and in- sertion, have been preserved. It is not expected that children will either be interested or required to learn this intricate division of anatomy, even should the first prin- ciples of the science be generally taught in common echools. For instructers, however, drawing-school pupils and young artists, the few technical words which are retained, will be of consequence, as they will be able to refer to the skeleton, (which we also hope will be considered, at no very remote period, an indispensable part of school appa- ratus,) for the exact places to which they refer. Note. — Where the muscle has no fellow, it is marked thus. * It should be recollected that the muscles of one side the body only, are here considered. 60 ANATOMICAL CLASS BOOK. MUSCLES OF THE HEAD, EYELIDS, EYEBALL, NOSE AND MOUTH. Name. Occipito-frontalis.* Corrugator supercilii. Orbicularis palpebrarum. Levator palpebrse superi- or is. Rectus superior. "\ Rectus inferior. f Rectus internus. ? Rectus externus. * Obliquus superior, or Tro- chlearis. Obliquus inferior. Fig 31. Arises from The upper ridge of the oc- cipital bone; its aponeurosis covers the upper part of the head. Above the root of the nose. Around the edge of the orbit. The bottom of the orbit near the optic foramen. Around the optic foramen of the sphsenoid bone, at the bottom of the orbit. Near the optic foramen, and passes through a loop in the internal canthus of the eye, and is reflected to be The ductus nasalis, and is inserted Explanation of Fig. 31. a, the pyramidalis nasi; o, the com- pressor nasi; a, oc- cipito frontalis; c, orbicularis palpe- brarum^, corruga- tor supercilii; n, le- vator palpebral supe- rioris ; f, zygomati- cus major; e, zygo- maticus minor; i, orbicularis oris; k, depressor anguli or- is ; m, depressor la- bii inferioris ; h, the masseter muscle ; g, the buccinator; d. levator labiisuperio- sis alceque nasi; g, the parietal bone seen beyond the cor- onal suture. m ANATOMICAL CLASS BOOK. 61 MUSCLES OF THE HEAD, EYELIDS, EYEBALL, NOSE AND MOUTH. Inserted into The skin of the eyebrows and root of the nose. The inner part of the occi- pito-frontalis. The inner corner of the eyes. The cartilage of the tarsus of the upper eyelid. The anterior part of the tunica sclerotica, opposite to each other. The posterior part of the bulb, between the rectus and the entrance of the optic nerve. Opposite to the former. Use. To pull the skin of the head backward brows and head. To wrinkle the eyebrows. - raise the eye- skin of the fore- To shut the eye. To open the eye, by raising the upper eyelid. To raise it upward. To pull it downward. To turn it to the nose. To move it outward. To roll the eye, and turn the pupil downward and out- ward. To roll the eye. By recurring to the plate, (Fig. 31,) the pupil will form a tolera bly accurate idea of the muscles of the face. They lie very super- ficially, just under the skin, and are all muscles of expression ; therefore only perfectly developed in the European, or white man's face, in whose countenance the passions of the mind are strongly exhibited. In the negro, owing partly to the color of the skin, the expression is necessarily very imperfect:—he can never have maj- esty nor dignity, or an elevation of thought, portrayed in his fea- tures. When the jet black negro expresses his emotions, — unless the teeth, and the whites of the eyes arc exposed,— there is little va- riety of expression, because no shades are created by the contrac- tions of the muscles. ThU fact is familiar to artists,— to the en- graver and the painter. The pictures of colored persons are always very nearly alike ; the portrait of one, indeed, will answer for many, — and the circumstance is wholly referable to the imperfect manner in which the light and shadows are created on the skin. The muscles of expression are fewer and smaller, as animals de- scend the scale of creation. 6 62 ANATOMICAL CLASS HOOK. Name. Levator labii superioris alseque nasi. Levator labii superioris pro- prius. Levator anguli oris. Zygomaticus major. Zygomaticus minor. Buccinator. Depressor anguli oris. Depressor labii inferioris. Arises from The nasal process of the superior maxillary bone. The upper jaw, under the orbit. The orbitar foramen of the sup. max. bone. The os jugale, near the zygomatic suture, and runs downward. Above the zygomaticus ma- jor. The pockets of the last mo- lares, and the coronoid pro- cess of the lower jaw. The lower edge of the un- der jaw, near the chin. The inferior part of the lower jaw, next the chin. ANATOMICAL CLASS BOOK. 63 Inserted into Use. The upper lip and ala of It raises the upper lip, and the nose. dilates the nostrils. The middle of the upper To pull the upper lip di- ]ip. rectly upward. The orbicularis, at the an- To raise the corner of the gle of the mouth. mouth. The angle of the mouth, To inflate the cheek and with the depressor of the lip. raise the angle of the mouth. The angle of the mouth. To raise the angle of the mouth outward. The angle of the mouth, To contract the mouth, and and is perforated by the duct draw the angle of it outward of the parotid gland. and backward. The angle of the mouth. To draw the corner of the mouth downward. The middle of the under lip. To draw the under lip down- wardand outward. Explanation of Fig. 32. d. The occipito-frontalis. e. The orbicularis palpebrarum. f. The corrugator supercilii. g. The compressor naris. h. The orbicularis oris. t. The levator labii superioris alaeque nasi. j. The levator anguli oris. k. The zygomaticus major and minor. 1. The depressor anguli oris. »«. The depressor labii inferioris, n. The buccinator. o. The masseter. p. The temporal fascia, or aponeurosis. 2. The parotid gland, which supplies the mouth with sahva. 3. Steno's duetto conduct the fluid into the mouth. 4. The temporal artery. 5. The facial artery. Parts seen in the neck. q. The sterno-cleido mastoideus. r. The omo-hyoideus. s. The sterno-hyoideus. t. The sterno-thyroideus. u. The digastricus. v. The stylo-byoideus. 10. The mylo-hyoideus. . H. The submaxillary gland — also pours saliva into the mouth. 7. The external jugular vein. S. The sheath containing the caroUd artery. 64 ANATOMICAL CLASS BOOK. Name. Orbicularis oris.* Depressor labii superioris absque nasi. Constrictor nasi. Levator menti vel labii in- ferioris. MUSCLES OF THE Superior auris, or attollens aurem. Anterior auris. Posterior auris, or retrahens auris. Helicis major. Helicis minor. Tragicus. A nti tragus. Transversus auris. MUSCLES OF TH Laxator tympani. Tensor tympani. Stapedius. Arises from This muscle surrounds the lips, and is in a great measure formed by the buccinator, zy- gomatic!, and others, which move the lip. The sockets of the upper incisor teeth. The root of one wing of the nose, and The lower jaw, at the root of the incisors. EXTERNAL EAR. The tendon of the occipito- frontalis above the ear. Near the back part of the zygoma. The mastoid process, by two and sometimes three fas- ciculi. The upper, anterior, and acute part of the helix. The interior and anterior part of the helix. The outer and middle part of the concha, near the tragus. From the root of the inner part of the helix. The upper part of the con- cha. INTERNAL EAR. The spinous process of the sphsenoid bone. The cartilaginous extremity of the Eustachian tube. A iittle cavern in the pe- trous portion, near the cells of the mastoid process. ANATOMICAL CLASS BOOK. 65 Inserted into Use. To shut the mouth, by con- tracting the lips. The root ofthe ala nasi and To pull the ala nasi and upper lip. uPPcr hP down' , . „ « The linea alba, ossa pubis, To compress the abdomen. and spine ofthe ilium. The cartilages of all the To compress the abdomen. false ribs, hnea alba, and pu- bis, and sternum, by a flat tendon. Explanation of Fig. 34. g. The obliquus internus, with its tendon divided, to show h. The pyramidalis. i. The rectus, abdominis. Beneath the internal oblique there is situated ' k. The transversalis abdominalis, and /. The fascia transversalis. The tendons of the abdominal muscles, form junctions in front where their broad white tendons meet, which are denominated lines; — and that which runs exactly in the middle, from the lower point of the sternum, to the pubis, is the linea alba or white line. Again, the long abdominal muscles, lying each side of this linea alba, arc intersected, several times, between their two extremities by similar tendinous lines, which, in reality, divides thern into a chain of muscles. This structure has reference to increasing their power, by a series of contractions, along their course, which thereby answers a second intention, viz, preserving a symmetry of form By consulting Fig. 34, page 72, both the vertical and transverse lines are discoverable. Statues representing action, invariably exhibit the muscles of the bowels thrown into ridges. Upon the princi- ples adverted to in the preliminary essay on myology, without these transverse bands, the bellies of the long recti muscle, in order to pull the chest, as in stooping for example, while seated in a chair, so as to bring the breast down to the knees, would have a bulk, by the process of contraction, equal to a two quart measure. By the introduction of the transverse tendinous lines, two vastly important results are obtained, — increased power and beauty of form. The linea alba throughout To compress the abdominal its whole length, and into the viscera. ensiform cartilage. The side of the symphysis To compress the abdomen, ofthe pubis. and bend the trunk. The linea alba, below the To assist the lower portion umbilicus. ofthe rectus. 74 ANATOMICAL CLASS BOOK. MUSCLES SITUATED WITHIN THE PELVI8. Name. Obturator internus. Coccygeus. Arises from The foramen ovale, obtura- tor ligament, ilium, ischium, and pubis. The spinous process of the ischium. MUSCLES SITUATED WITHIN THE CAVITY OF THE ABDOMEN. Quadratus lumborum. Psoas parvus. The posterior part of the spine of the ilium. The transverse process of the last dorsal vertebra. Fiff. 35. Explanation of Fig. 35 K. The iliacus internus. R. The psoas magnus. S. The obturator exter- nus. ANATOMICAL CLASS BOOK. 75 MUSCLES SITUATED WITHIN THE PELVIS. Inserted into Use. A large pit between the tro- To roll the femur obliquely chanters ofthe femur. outward. The extremity of the sa- To move the coccyx for- crurn and os coccygis. ward and inward. MUSCLES SITUATED WITHIN THE CAVITY OF THE ABDOMEN. The transverse apophyses To support the spine and of the loins and last spurious draw it to one side. rib. The brim of the pelvis, To bend the loins forward. near the place of the aceta- bulum. On the inside of the broad hip bone, os innotninatum, seen on the opposite page, Fig. 35, and also running up by the side of the lumbar vertebrae, thiee muscles have their origin, — that bear a highly im- portant part in the locomotive power ot the body. In these, as in every other place in the system, a two fold intention is answered. First, — these three muscles are cushions,— on which the coils of the intestines reit. Wiihout them, some other provision would have been necessary, as a soft bed is indispensable for the.;., in the violent exercises of running, leaping, or even walking Secondly, the tendons of the psoas magnus and iliacus internus, are sent over the brim of the pelvis, to wind down the inside ofthe groin, close to the bone, to reach the backside of the thigh bone, where they are fast- ened. Obscure as they are, these muscles, when standing on our feet, maintain the body in an erect position. If we desire to move forward, these muscles lift up the whole limb,— and when they re- lax, the foot strikes the ground again. If, while sitting, the knee is raised towards'the chest, the act is accomplished by thete two mus- cles. In walking and running, therefore, as they are the lifters-up of the leg, their services could not be dispensed with. A lumbar abscess, a painful disease, wholly forbidding the movement of the limb ofthe side in which it occurs, is a collection of matter under the psoas magnus, and next to the back bone, near the line R, on the plate. As the abscess cannot be very safely discharged by a surgical operation, through the muscles ol the back, in protracted cases, the matter sometimes follows the muscles, quite into the limb, and forces its way down, even to the knee, before it escapes. This dreadful disease has been induced, by lying on the damp ground, after freely exercising; and by unnecessary feats of strength, in lifting burdens, in the careless days of youthful vigor. 76 ANATOMICAL CLASS BOOK. Name. Psoas magnus. Iliacus internus. Arises from The bodies and processes of the last dorsal and all the lumbar vertebrse. The internal surface of the spine of the ilium. MUSCLES SITUATED ON THE ANTERIOR PART OF THE THORAX. Pectoralis major. The clavicle, sternum and seven true ribs. Fig. 36. Subclavius. Pectoralis minor. The cartilage ofthe first rib. The third, fourth, and fifth ribs. 99 ANATOMICAL CLASS BOOK. 77 Inseiied into Use. The os femoris, a little be- To bend the thigh forward. low the trochanter minor. The femur in common with To assist the psoas magnus. the psoas magnus. MUSCLES SITUATED ON THE ANTERIOR PART OF THE THORAX. The upper and inner part of To draw the arm forward, the humerus. or obliquely forward. Explanation of Fig. 36. a. The pectoralis major. b. b. The obliquus abdominis externus descendens : beneath these muscles the following:— c. The pectoralis minor. d. The serratus magnus anticus. e. The external intercostal muscles. f. The internal intercostal muscles. g. The obliquus abdominis internus ascendens. By returning to the anatomy of the ribs, it is there shown that they are constructed to move :—breathing is effected by increasing and diminishing the capacity of the chest, as the lungs are inflated or collapsed. To carry on this operation, an appropriate class of muscles take their rise on, and about the ribs and sternum, to be ex- clusively engaged in this respitory action. Between the edges of the ribs, short oblique muscles, one the internal and the other the external, crossing each other, like suspenders on a man's back,— are untiring in their labors: — when they contract, the ribs are brought together; and when relaxed, the diameter of the chest is enlarged. All the muscles on the breast and sides, are remotely respitory agents. If the arms are fixed, by their contraction the ribs are drawn outwardly. Asthmatic persons, because the small intercostal muscles do not relax enough, bring the pectoral muscles to their aid, by raising their hands and holding on to a door, or a beam, for example, above the head. This enables them to pull open, as it were, the bottom of the chest. Ladies often swoon and sometimes dropdown dead instantly, in consequence of lacing the chest so tightly, that the ribs cannot possibly move. The under surface of the To move the clavicle down- clavicle, ward. The coracoid process ofthe To roll the scapula. scapula. 7* 78 ANATOMICAL CLASS BOOK. Name. Serratus major anticus. Arises from The eight superior ribs. MUSCLES SITUATED BETWEEN THE RIBS AND WITHIN THE THORAX. Intercostales externi. Intercostales interni. Triangularis, or Sterno-costalis. The lower edge of each upper rib. Like the former, their fibres are directed from behind for- ward. The middle and inferior part ofthe sternum. MUSCLES SITUATED ON THE ANTERIOR PART OF THE NECK, CLOSE TO THE VERTEBRA. Longus colli. Rectus internus capitis ma- jor. Rectus internus capitis mi- nor. Rectus capitis lateralis. The bodies of the three upper dorsal and transverse processes of the four last cervical. The transverse processes of the five last cervical vertebrae. The fore part of the atlas. The transverse process of the atlas. MUSCLES SITUATED ON THE POSTERIOR PART OF THE TRUNK. The os occipitis and the spinous processes of all the vertebrae of the neck and back. The spine ofthe ilium spin- spinous process of the sacrum, lumbar and inferior dorsal ver- tebrae ; adheres to the scapula and inferior false ribs. The spinous processes of the two last dorsal and three lumbar vertebrae. Trapezius, or Cucullaris. Latissimus dorsi. Serratus posticus inferior. ANATOMICAL CLASS BOOK. 79 Inserted into Use. The base of the scapula. To bring the scapula for- ward. MUSCLES SITUATED BETWEEN THE RIBS AND WITHIN THE THORAX. The superior edge of each To elevate the ribs. lower rib. The cartilages of the five To depress the cartilages last true ribs. ofthe ribs. MUSCLES SITUATED ON THE ANTERIOR PART OF THE NECK, CLOSE TO THE VERTEBRjE. The anterior tubercle of the To pull the neck to one dentatus. side. The cuneiform process of To bend the head forward. the os occipitis. The os occipitis, near the To assist the former. condyloid process. The os occipitis, near the To move the head to one mastoid process. side. MUSCLES SITUATED ON THE POSTERIOR PART OF THE TRUNK. The clavicle, part of the To move the scapula, bend acromion, and the spine of the the neck, and pull the head scapula. backward. The os humeri, between its To draw the os humeri two tuberosities in the edge backward, and to roll it upon of the groove for the tendon its axis. ofthe biceps muscle. The lower edge of the three To draw the ribs outward, or four lowermost ribs, near downward, and backward. their cartilages. 80 ANATOMICAL CLASS BOOK. Name. Rhomboideus. Splenius. Serratus superior posticus. Spinalis dorsi. Levatores costarum, or Supra-cotales. Sacro-lumbalis. Arises from The spinous processes of the three last cervical, and four first dorsal vertebrae. The spines of the four last cervical, and four superior dor- sal vertebrae. The spinous processes of the three last cervical, and two superior dorsal vertebrae. Two spinous processes of the loins, and.three lower of the back. The transverse processes of the last cervical and the dor- sal vertebrae. The sacrum, spine of the ilium, and the spinous and transverse processes of the lumbar vertebrae. Fig. 37. Explanations of Fig. 37. a. The trapezi- us. b. The latissimus dorsi. c. The rhomboi- deus minor. d. The rhomboi- deus major. e. The serratus posticus inferior. /. The levator anguli scapulae. Blocks were in- troduced to repre- sent the figure in a horizontal position, that the muscles might be more dis- tinctly seen. ANATOMICAL CLASS BOOK. 81 Inserted into The basis ofthe scapula, at its upper and lower part. The two first cervical verte- brae, and the side of the os ocdipitis. The second, third, and fourth ribs, by three neat fleshy tongues. All the spinous processes of the back, except the first. The angles of the ribs. Use. To move the scapula up- wards and backward. To move the head back- ward, and also to one side. To expand the thorax, by elevating the ribs. To extend the vertebrae. To lift the ribs upward. The lower edge of each rib, by a flat tendon. To draw the ribs down- ward, to move the body upon its axis, to assist the longissi- mus dorsi, and to turn the neck back, or to one side. All the muscles of the back, clearly defined in Fig. 37, on the opposite page, are broad, thin, and generally produce the slow mo- tion of the limbs. In the middle of the trapezius, marked a, is a white line, where the fibres of the muscle, on either side meet and adhere to the spinous processes of the bones of the neck. On this line, in quadrupeds, is placed a powerfully strong cord, by the far- riers called paxwax,—but by anatomists — Itgamentum nucha, which, being attached to the back bone, between the shoulders, pre- vents their heavy head from drooping to the ground, It will not re- lax : —when they drink or feed, on a level with their feet, the nose, even by a voluntary effort, barely reaches to the earth. 82 ANATOMICAL CLASS BOOK Fig. 38. ANATOMICAL CLASS BOOK. 83 Explanation of Fig. 38. a, upper portion of the trapezius; i. sterno cleido mastoideus ; d. the deltoid portion of the trapezius; f. the latissimus dorsi; n. n. n. n. portions of the latissimus, rising by digitations from the ribs; g. and b. tendinous continuation of the latissimus into the fibres of the gluteus maximus ; h. the deltoides muscle, to raise the arm; k, e, m, the infra spinatus, belonging to the shoulder; c, the clavicular portion ofthe deltoides ; I, the intermingling of the fibres of the gluteus maximus, and latissimus dorsi. The artist was particularly fortunate in delineating the muscles in the accompanying diagram. No plate could more accurately show the relation which one bears to the other, nor more truly represent the converging fibres, all centering in the tendons. As in the de- monstration ofthe eye, it can also be said here, —that there are coats of muscles on the back and sides. One overlap? the edges of another, in such a perfect manner, as to leave no deep spaces :— an even covering is thus spread over the skeleton. The latissimus dorsi. marked/, is one of the most beautiful in the body; and its utility is proved every moment. Its office is to bring down the hand. Before man invented instruments which have superseded, to consid- erable extent, the primitive use of the hand, in some particulars, — his fist was a mallet,— the arm the handle, and this muscle, the power that gave force to the blow. Those mechanics who are con- stantly using hammers, and axes, increase its size and strength, amazingly. If the arm, on the other hand, be firmly fixed, in a horizontal position, the digitations marked n, n, n, n, by their strong hold upon the false ribs, would open the bottom of the chest, quite effectually. Over the shoulder joint, and from thence, running to the middle of the arm bone, is a splendid muscle, —the deltoides, marked A, which raises the arm to a level with the shoulder; its lateral portions, even carry the elbow very much above the level of their origin. If it were divided, no remaining muscle could per- form its office. J ii-Jl above /, winding partially under the deltoides, is that muscle which extends the arm. The name of triceps exten- sor cubiti U given it, because it arises by three heads, which uniting in one tendon, passes the elbow joint, on the back of the arm, to be inserted into the ulna, or, as the bone is sometimes called, the cubit. Lastly, k, e, m, directs the eye to the infra spinatus, arising on tha external surface of the shoulder blade, and inserted into the arm bone. By its contraction, the arm is raised a very little, and carried backward;— its tendon, as it passes over the shoulder joint, adheres to the capsular ligament and keeps it drawn out, so that it may not be pinched, by the rolling motion of the ball in the socket. 84 ANATOMICAL CLASS BOOK. Name. Longissimus dorsi. Complexus. Trachelo-mastoideus. Levator scapulae. Semi-spinalis dorsi. Multifidus spinas. Semi-spinalis colli, or Spinalis cervicis. Transversalis colli. Rectus capitis posticus ma- jor. Rectus capitis posticus mi- nor Obliquus capitis superior. Obliquus capitis inferior. Scalenus. Interspinals. Inter-trans versales. Arises from The same parts as the for- mer, and by one common broad tendon. The transverse processes of the four inferior cervical, and seven superior dorsal verte- brae. The transverse processes of the five lower cervical and three upper dorsal vertebrae. The transverse processes of the four superior cervical ver- tebrse. The transverse processes of the 7th, 8th, 9th, and 10th dorsal vertebrse. The sacrum, ilium, oblique and transverse processes of the lumbar, the transverse of the dorsal, and four cervical vertebrse. The transverse processes of the six upper dorsal verte- brae. The transverse processes of the five upper dorsal verte- brae. The transverse process of the second cervical vertebrae. The first vertebrae of the neck. The transverse process of the atlas. The spinous process of the dentatus. The upper surface of the first and second rib. Between the spinous pro- cesses of the six inferior cer- vical vertebrae. Between the transverse processes of the vertebrse. ANATOMICAL CLASS BOOK. So Inserted into The transverse processes of all the dorsal and one cervical vertebra. The middle of the os occi- pitis, at its tubercle. The os occipitis, behind the mastoid process of the tempo- ral bone. The upper angle of the scapula. The spinous processes of the four superior dorsal and ■the last cervical vertebrse. The spinous processes ofthe lumbar dorsal, and cervical vertebrae, except the atlas. The spinous processes of the five middle cervical. The transverse processes of the cervical vertebrae The lower ridge of the os occipitis. The os occipitis at its tu- bercle. The end of the lower occi- pital ridge. The transverse process of the atlas. The transverse processes of the cervical vertebrae. The spinous processes of the vertebrse above. The transverse processes of the vertebrae above. Use. To stretch the vertebrae of the back, and keep the trunk erect. To draw the head back- ward. To draw the head backward. To move the scapula for- ward and upward. To extend the spine ob- liquely backward. To extend the back, and draw it backward, or to one side, and prevent the spine from being too much bent for- ward. To stretch the neck ob- liquely backward. To turn the neck obliquely backward, and to one side. To extend the head, and draw it backward. To assist the rectus major. To draw the head back- ward. To draw the face to one side. To move the neck forward, or to one side. To draw the spinous pro- cesses towards each other. To draw the transverse pro- cesses towards each other. 3 86 ANATOMICAL CLASS BOOK. MUSCLES OF THE SUPERIOR EXTREMITIES. Name. Supra-spinatus. Infra spinatus. Arises from The basis, spine, and upper end ofthe scapula. The cavity below the spine ofthe scapula. Fig. 39 Explanation of Fig. 3i). a. The supra-spinatus. b. The infra spinatus. c. The teres minor. d. The teres major. e. The latissimus dorsi. /. The deltoid. g. The triceps extensor cubiti. Teres minor. Teres major. Deltoides. Coraco brachialis. The inferior edge of the scapula. The inferior angle and edge ofthe scapula. The cavicle, and the acro- mion and spine of the scapula. The coracoid process ofthe scapula. ANATOMICAL CLASS BOOK. 87 MUSCLES OF THE SUPERIOR EXTREMITIES. Inserted into Use. A large tuberosity at the To raise the arm. head ofthe os humeri. The upper part ofthe same To roll the os humeri out- tuberosity. ward. Anatomists have sought for an explanation ofthe superiority of the right hand, over the left, in the muscles, arteries and nerves of the arm; but no very satisfactory light has been thrown upon the subject. Atone time, it was a common mode of getting over the difficulty, to say that the preference we give to the right hand aiises from its superior strength ; and that quality is owing to the man- ner in whicli the artery arises from the arch of the aorta, just above the heart. There is certainly a considerable difference in the size ofthe arteries in the two aims. The right in this respect, being the largest, derives its blood more directly from the fountain head. As the power of the muscle actually depends on the blood circulat- ed in its substance, it was very natural to refer the origin of its su- perior force to this cause. Here the inquiry has rested, so far as anatomical demonstration is concerned. But a formidable objection to that old fashioned theory arises, when we find a left-handed man, whose ann does not differ essentially from any other person's left arm, and ambidexters, men using one hand just as well as the other, for example, in writing, throwing balls, turning a gimblet, using a cabi- net-maker's plane, &c, seem to be entirely out of the reach of the old stereotyped theory about the artery. The preference, given to the right hand, conduces to its muscular development; it is both larger, and stronger, by use. So it is with the right foot, and fvnce the extreme difficulty, with some, of wearing a pair of shoes made on one last. The evidence is pretty conclusive, from the universality of the law. which embraces all the inferior animals, as well as man, that it was expressly designed by the Creator, that the limbs on one side of the body should possess certain physical advantages over the other. Both rapidity of motion, and strength, are thus combined, constantly improved upon by practice, and a certain mechanical excellence is thus bestowed, without which we should be incompetent to the discharge of those duties which devolve upon us. The greater tuberosity of To assist the former. the humerus. The side of the groove for To assist in rotating the the long tendon of the biceps, arm. The anterior and middle To raise the arm. part ofthe 03 humeri. The middle and inner side To roll the arm forward and of the os humeri. upward. ANATOMICAL CLASS BOOK. MUSCLES SITUATED ON THE OS HUMERI. Name. Subscapularis. Biceps flexor cubiti. Brachialis internus. Triceps extensor cubiti. Anconeus. Arises from The basis, superior and in- ferior edge ofthe scapula. Two heads, one from the coracoid process, the other, called the long head, from the edge of the glenoid cavity ofthe scapula. The os humeri at each side ofthe tendon of the deltoides. The neck of the scapula, and the neck and middle of the humerus. The external condyle of the humerus. MUSCLES SITUATED ON THE FORE ARM Supinator radii longus. Extensor carpi radialis lon- gior. Extensor carpi radialis bre- vior. Extensor digitorum commu- nis. Extensor minimi digiti. Extensor carpi ulnaris. Flexor carpi ulnaris. Palmaris longus. Flexor carpi radialis, Pronator radii teres. Supinator radii brevis. The external condyle ofthe humerus. The external condyle ofthe humerus. The external condyle of the humerus. The external condyle ofthe os humeri. The outer condyle of the humerus. The outer condyle ofthe os humeri. The inner condyle of the humerus and olecranon. The internal condyle ofthe os humeri. The internal condyle ofthe os humeri. The internal condyle ofthe humerus and coronoid process ofthe ulna. The outer condyle of the humerus and edge ofthe ulna. ANATOMICAL CLASS BOOK. 89 MUSCLES SITUATED Inserted into The protuberance at the head ofthe os humeri. The tuberosity at the upper end of the radius, at its fore part', and a little below its neck. The coronoid process ofthe ulna. The upper and outer part ofthe olecranon. The back part or ridge of the ulna. MUSCLES SITUATED The radius near the styloid process. The metacarpal bone of the fore finger. The metacarpal bone ofthe middle finger. The back of all the bones ofthe fingers. The second joint of the little finger. The metacarpal bone of the little finger. The os pisiforme, at its fore- part. The annular ligament of the wrist, and there forms the aponeurosis of the hand. The metacarpal bone ofthe fore finger. The outer ridge of the radi- us, about the middle of its length. The anterior, inner, and upper part ofthe radius. ON THE OS HUMERI. Use. To roll the arm inward. To bend the fore arm, which it does with great strength, and to assist the supinators. To assist in bending the fore arm. To extend the fore arm. To assist in extending the fore arm. ON THE FORE ARM. To assist in turning up the palm ofthe hand. To extend the wrist. To assist the former. To extend the fingers. To assist in extending the fingers. To assist in extending the wrist. To assist in bending the hand. To bend the hand. To bend the hand. To roll the hand inward. To roll the radius outward, and assist the anconeus. 8* 90 ANATOMICAL CLASS BOOK. Na me. Arises from Extensor ossis metacarpi The middle of the ulna, in- pollicis manus. terosseous ligament and radius. Fig.41. ANATOMICAL CLASS BOOK. 91 Inserted into Use. The os trapezium, and first To stretch the first bone of bone of the thumb. the thumb outward. Explanation of Fig. 40. /. extensor digitorum communis, for extending the fingers; h, ex- tensor proprius minimi digiti, to extend the little finger; f, where it unites with others; i, extensor carpi ulnaris; I, anconeus, ex- tensor ossis metecarpi pollicis; e, ertensor primi internodii pollicis ; e, extensor secundi internodii pollicis; d, indicator; g, annular ligament of the wrist; m, will be recognised; k, an abductor of the little finger ; e, supinator radii longus. Explanation of Fig. 41. a. pronator teres; b, flexor carpi radialis ; c, d, palmaris longus; e, flexor carpi ulnaris ; g, flexor carpi radialis longoir. Between the elbow and ends of the fingers there are about fifty muscles. Some of them,— particularly those by the sides of the fing- ers, are quite short and delicate. All the quick short motions ofthe fingers are made by them. Their name, musculi fidicinales, fiddling muscles, in old books, is quite appropriately given, because the strings of the instrument are operated upon almost entirely by them. A back and front view of the fore arm is presented in the opposite page, Fig's 40, and 41, in which all the long mus- cles, on the inside flexors, and on the back of the arm exten* sors', may be very accurately observed. Just under the skin, a silvory, tough membrane, like a silk case, is drawn closely over the muscles, to keep them from swelling too much, in their contractions. As before remarked, the strength which a muscle exerts, by being pressed down to the bone, when in action, is increased a hundred fold. The beauty and proportion of the limb is wholly preserved by the case, which is called fascia. It is taken away, in these plans, in order to show more distinctly the parts below. 92 ANATOMICAL CLASS BOOK. Name. Arises from Extensor primi internodii. Near the middle of the ulna, interosseous ligament, and radius. Extensor secundi interno- The back of the ulna and dji# interosseous ligament. Indicator. The middle of the ulna. Fig. 43. V P, ANATOMICAL CLASS BOOK. 93 Inserted into Use. The convex part of the To extend the second bone second bone ofthe thumb. ofthe thumb outward. The third and last bone of To stretch the thumb ob- the thumb. liquely backward. The metacarpal bone ofthe To extend the fore finger. fore finger. Explanation of Fig. 42. d, e, flexor digitorum sublimis, attached to the second bone of each finger, by four tendons, to bend the second joint,—/, h, flexor longus policis manus, to bend the thumb ; a, b, c, pronator teres, to pronate the hand ; g, a slit in the tendons of the flexor digitorum for the passage of four other tendons of another muscle which go tc the points of the fingers, for bending the last joint. Explanation of Fig. 43. c, d, d, the pronator quadratus, is one of two small muscles for pronating the hand; a, b, the other,—pronator teres. In Fig's. 42, and 43, the muscles are distinctly engraven, which roll tho fore arm in supination and pronation. By turning a key in a door-lock, both sets are called into action, and it is recommend- ed to the reader to do it, and at the same time to feel the contractions of the muscles with the other hand. Fig. 43, the bones are made so plain, as to show the exact relation which the pronators have to them. On the other, Fig. e, points to.the lour tendons of the muscle that bends the last bone of the fingers. Looking back to Fig. 41, page 90, it is there concealed by the flexor of the second bone of the fingers. This, in order to reach its place of destination, pierces, as it were, the tendons of the upper muscle, and thus sends its own tendons onward, through the slit. 94 ANATOMICAL CLASS BOOK. Name. Flexor digitorum sublimis. Flexor digitorum profundus vel perforans. Flexor longus pollicis. Pronator radii quadratus Arises from The inner condyle ofthe os humeri, coronoid process ofthe ulna, and upper part of the radius. The upper part of the ulna, and interosseous ligament. The upper and fore part of the radius. The inner and lower part ofthe ulna. MUSCLES SITUATED CHIEFLY ON THE HAND Lumbricales. Flexor brevis pollicis manus. Opponens pollicis. Abductor pollicis manus. Abductor pollicis manus. Abduotor indicis manus. Palmaris brevis. Abductor minimi digiti man- s. Abductor minimi digiti. Flexor parvus minimi digiti. Interosseiinterni, and Interossei extend. The tendons of the flexor profundus. The os trapezoides, liga- ment of the wrist, and the os magnum. The os scaphoides and liga- ment ofthe wrist. The annular ligament, and os trapezium. The metacarpal bone ofthe middle finger. The first bone of the thumb, and os trapezium. The annular ligament, and palmar aponeurosis. The annular ligament and os pisiforme. The os cuneiforme and car- pal ligament. The annular ligament and os cuneiforme. The metacarpal bones. MUSCLBS OF THE INFERIOR EXTREMITIES. Pectinalis. The anterior edge of the os pubis. ANATOMICAL CLASS BOOK. 95 Inserted into The second bone of each finger, after being perforated by the tendons of the profun- dus. The fore part of the last bone of each ofthe fingers. The last joint ofthe thumb. The radius opposite to its origin. Use. To bend the second joint of the fingers upon the first, and the first upon the metacarpal bones. . . To bend the last joint of the fingers. To bend the last joint of the thumb. To roll the radius inward. MUSCLES SITUATED CHIEFLY ON THE HAND. The tendons ofthe extensor digitorum communis. The ossa sesamoidea and second bone ofthe thumb. To bend the first and extend the second phalanx. To bend the second joint of the thumb. The first bone ofthe thumb. To bend the thumb. The root ofthe first bone of the thumb. The root ofthe first bone of the thumb. The first bone of the fore tinker posteriorly. The metacarpal bone and skin ofthe little finger. The first bone of the little finger. The metacarpal bone of the little finger. The first bone of the little finger. The sides ofthe metacarpal bones. To draw the thumb from the fingers. To pull the thumb toward the fingers. To move the fore finger to- wards the thumb. To contract the palm ofthe hand. To draw the little finger from the rest. To move that bone toward the rest. To draw the little finger from the rest. To extend the fingers, and move them toward the thumb. MUSCLES OF THE INFERIOR EXTREMITIES. The upper part ofthe linea To bend the thigh. aspera ofthe femur. 9G ANATOMICAL CLASS BOOK. Name. Adductor longus femo- s. Adductor brevis femo- 3. Adductor magnus femo- s. Fig. 44. Arises from The upper and fore part of the pubis. The fore part and ramus of the os pubis. The lower and fore part of the ramus ofthe pubis. Explanation of Fig. 44. c. The gluteus medius. d. The pyriforniis. e. The geminus superior. /. The geminus inferior. g. The obturator internus. g*. The quadrator femoris. h. The biceps flexor cruris. i. The semitendinosus. k. The semimembranosus 1. The superficial gluteal artery and nerve. m. The greatischiaticnerve. n. The ischiatic artery. o. The popliteal nerve. p. The fibular or peroneal nerve. q. The popliteal vein. r. The popliteal artery. s. The internal pudic artery vein, and nerve. t. t. The muscles on the anterior part of the thigh. ANATOMICAL CLASS BOOK. 97 Inserted into Use' The middle and back part To bend the thigh. of the linea aspera. The inner and upper part To bend the thigh, and of linea aspera. move it inward. The whole length of the To move the thigh inward, linea aspera. and assist in bending it. Besides the muscles, nerves, veins, tendons, bands, and ligaments, there a« absoibents-w exceedingly minute class of tubes.of.he utmost importance in the animal economy. From the inner edge of the great toe, to the groin, there is a chain of absorbents, >e- sembhnl when magnified by a lens, a multitude of threaded eggs. UU the office of the absorbents to pick up whatever ro*ht otherwise have been wasted, and return it to the heart, that ,t may be appro- priated m the wants of the body. These egg-shaped part.cle* are receiving organs, immensely larger than the tubes which bring into them the fluids they suck up about the muscles By the agency of these small bodies, which are greedy to seize whatever is presented to them, the physician is able to convey medicines into the circula- tion, when they could not be taken into the stomach It may be desirable to salivate, or in other words, to increase the quantity of fluid in the mouth, in order to overcome some local disease, but as mercury, in the form best adopted to produce that effect, would be injurious to swallow, it is rubbed on the skin, oyer these lymphat- ics or absorbents,being called by either name, which at once convey it into the blood; —but being offensive and injurious to the body, ano- ther set of vessels discover the presence ofthe unwelcome visitor, and speedily go to work to throw it out ol the system. IiUhe case of mercu- ry it is conveyedout at the mouth, and the great flow of saliva which keeps up a constant spitting, is nothing more than nature s scheme to wash away the noxious matter. These absorbents sometimes suck in a poisonous matter-. — here an action at once takes place, of an extraordinary character. It seem as though the lymphatic thus loaded, was conscious of its destructive burden, and instead of allowing it to flow to the next one towards the heart, it inflames, bursts open, and discharg- es its contents in the form of a sore. Sometimes this ulceration may extend to the neighboring lymphatic, and so the disease be propagated even into the cavities ofthe body. If a serpent s fang wound the skin, the absorbents convey the venom onward, like couriers, to head-quar- ters the heart, whence it is distributed at once through the sys- em ' If a bee stings, the poison is ushered along by the same organs. The absorbents are exceedingly active agents, but so small, that their existence was unknown, a long time after the discovery of the circulation. 9 98 ANATOMICAL CLASS BOOK. Name. Obturator externus. Gluteus maximus. Gluteus medius. Gluteus minimus. Pyriformis. Gemini. Quadratus femoris. MUSCLES SITUATE Facialis, or Tensor vaginae femoris. Sartorius. Gracilis. Rectus femoris, or Rectus cruris. Vastus externus. Vastus internus. Cruralis, or Cruras us. Semi-tendinosus. Semi-membranosus. Arises from The obturator ligament, and half ofthe thyroid hole. The spine of the ilium, pos- terior sacro ischiatic ligaments, and os sacrum. The spine and superior sur- face ofthe ilium. The outer surface of the ilium and border of its great notch. The anterior part of the os sacrum. The spine and tuberosity of the ischium. The tuberosity of the is- chium. I) ON THE THIGH. The upper spinous process ofthe ilium. The upper spinous process ofthe ilium. The fore part of the ischium and pubis. The lower spinous process of the ilium, and edge of the acertabulum. The root of the great tro- chanter, and linea aspera. The trochanter minor, and the linea aspera. The anterior part of the lesser trochanter. The tuberosity of the is- chium. The tuberosity of the is- chium. ANATOMICAL CLASS BOOK. 99 Inserted into The femur near the root of the great trochanter. The upper part of the linea aspera ofthe femur. The great trochanter of the os femoris. The root of the great tro- chanter. A cavity at the root of the great trochanter. The same cavity as the pyrifonnis. A ridge between the two trochanters. Use. To pull forward, and rotate the thigh. To extend the thigh, and assist in its rotatory motion. To assist the gluteus maxi- mus. To assist the two former. To roll the thigh outward. To roll the thigh outward. To move the thigh outward. MUSCLES SITUATED The inner side of the mem- branous fascia which covers the thigh. The upper and inner part of the tibia. The upper and inner part ofthe tibia. The upper and fore part of the patella. The upper and lateral part ofthe patella. The upper and inner part of the patella. The upper part of the patel- la. . The upper and inner part ot the tibia. The back part of the head ofthe tibia. ON THE THIGH. To stretch the fascia. To bend the leg inward. To bend the leg. To extend the leg. To extend the leg. To extend the leg. To extend the leg. To bend and draw the inward. To bend the leg. 100 ANATOMICAL CLASS BOOK. Explanation of Fig. 43. a. The tensor vag- inae femoris. b. The sartorius. c. The rectus fe- moris. d. The vastus ex- ternus. e. The vastus in- ternus. /. The pectinalis. g. The adductor a longus. h. The adductor magnus. i. The gracilis. k. Iliacus internus. 1. The anterior crural nerve. m. The femoral ar- tery. n. The femoral vein. 1. The external ep- •c igastric artery. 2. 1 he external cjr- cumflcxa ilii. Name. Biceps fluxor cruris. Arises from The tuberosity of the is- chium. Pop'iteus. The external condyle ofthe thigh bone. ANATOMICAL CLASS BOOK. 101 To a person unaccustomed to anatomical language, the names of the muscles will undoubtedly appear exceedingly unmeaning, and difficult to pronounce. This is true, as respects the pronunciation; but the name, in a majority of cases, is really expressive, — giving both origin and insertion. An example of this double office of the name, may be noticed in stylo-glossus — meaning that it arises from the styloid process, and is inserted into the tongue. In hyo-glossus, the same advantage occurs: it simply informs us that it arises from the hyoideus, the bone ofthe tongue, and is inserted into the tongue. The muscles ofthe thigh and leg, are particularly vexatious, in this respect, to a young beginner. However, by patiently exercising the mind, in a little time the system becomes familiar. Though one bone only is embraced by the muscles of the thigh, the circumference is vastly greater of this part of the limb, than the leg. This depends on the number and magnitude ofthe muscles, which pass over the femoris, from the pelvis, to reach the bones of the leg below the knee joint. All the muscles on the fore part of the thigh, come from the upper end of the bone, and the hip, or ilium, and instead of being at all devoted to the service of the bone over whose surface they run, they are all concentrated in the knee pan, and therefore belong to the leg, as its extensors or straighteners. So violently have they been known to contract, that they have actually broken the knee pan into two pieces, — one half held by its ligament, down to its place, but the other, drawn by the uncontroled energy of the muscles, several inches up the thigh. When rising from a sitting posture, the entire weight ofthe body is raised by these same muscles; but they would be inadequate to the task, were it not for the sliding of the knee pan up the thigh, thereby increasing the power, by re- moving the fulcrum from the centre of motion, till the body is erect, when it slips into a pit, made by the meeting ofthe ends ofthe thigh and lee bones. While sitting, the muscles being at rest, the knee pan falls into the space between the ends of the bones, made by bending the limb. It is on this principle that the sessamoid bones are thrown in under the tendons ofthe toes, to increase the power ofthe flexor, by removing the centre of motion further from the joint. This is a plan of nature's to protect the toe, which, being over worked, would be ruined, were not an immediate provision made for increasing its power to meet the exigency of the case. Inserted into The upper and back part of the tibia, forming the outer hamstring. The upper and inner part of the tibia. 9* Use. To bend the leg. To assist in bending the leg. 102 ANATOMICAL CLASS BOOK. MUSCLES SITUATED ON THE LEG. Name. Arises from Gastrocnemius externus, or The internal and external Gemellus. condyle of the femur. ANATOMICAL CLASS BOOK. 103 Explanations of Fig. 46. a. Tensor vaginae femoris. b. Sartorius reflected. c. Rectus reflected. d. Vastus externus. e. Vastus internus, pulled outward. f. Pectinalis reflected. g. Adductor longus reflected. h. Adductor magnus. i. Gracilis. k. Iliacus internus. I. The anterior crural nerve. m. The femoral artery. 5. The arteria profunda. 6. The external circumflex artery. 7. The internal circumflex artery. n. The femoral vein. o. The cruralis. p. The adductor brevis. q. The obturator artery and nerve. o. The cruralis, vel crureus. p. The adductor brevis. Were it not for the tendons of the vast number of muscles which slide by the knee joint, as remarked in speaking of the anatomy of the bones, this would have been an imperfect articulation. Behind, the hamstrings contribute, on either side, to the formation of a canal, in which the artery, vein and great nerve of the leg, carefully cushioned up in a quantity of fat, lie so securely, that they very rai tly come to any injury. One object of introducing Fig. 45, opposite, was to show the general relation of some of the blood vessels,— the nerve that supplies the fore part of the thigh, and to exhibit the muscles already shown in a preceding figure, differently displayed, which have such a bearing on the anatomy of the joint. Several of the long ones are divided, in order to give a clearer view of those which would otherwise be too much hidden, to be understood. The sarto- rius or tailor's muscle, so called because it crosses the legs, is marked c — the upper portion being taken away to show i, the gracilis. In nearly all operations on the artery of the thigh, the surgeon is guided by the edge of the sartorius — a sure index ; it also contrib- utes to the lateral security of the knee. MUSCLES SITUATED ON THE LEG. Inserted into Use. The os calcis, with the To extend the foot. tendon ofthe soleus. 104 ANATOMICAL CLASS BOOK. *nme. Arisesfrom Gastrocnemius internus, or The head of the fibula, and back part of the head of the tibia. The outer condyle ofthe os femoris and capsular ligament. Fig. 48. Sole us. Plantaris ANATOMICAL CLASS BOOK. 105 Inserted into Use. The os calcis, by a common To extend the foot. tendon, which is called tendo "*¥£' os calcis, near the To assist in extending the tendo Achilis. foot. Explanations of Fig- 47. h. The tibialis anticus. »'. The extensor longus digitorum. A:. The peroneus tertius. /. The extensor longus, or propnus pollici-. m. Thii extensor digitorum brevis. n. The p-roneus longus. o. The peroneus brevis. p. The annular ligament. Explanations of Fig- 4S. h. The tibialis anticus. i. The extensor longus digitorum. I. The extensor longus pollicis. q. The anterior tibial artery. r. The anterior tibial nerve. A similar provision is made in the leg for keeping the muscles down o heirToper places, that has been noticed in the lore arm. Those band .called annular ligaments, which encircle the ankle, to nrevent the tendons, as they run upon the top of the instep, from flyingou t from the bones, ina high state of contractu* .must excite ny.ng uum constant tendency to do. If a n " of is" alkJng up ^flight of stairs on his toes, he will then per- Live the iron* action of the tendons, and the reaction of the liga- ments upon Sn. All those animals which climb, as squirrels, men s upon i"e,u- others have the fascia or limb cases, monkeys, bears, and torne others nave ^ Sa tioos have a beautiful web of ligamentary threads woundround 1 e lei iust above the toes, for restraining the tendons. F z 46 displays an intricate mass of muscles, originating: between the upper extremities of the leg bones. For nearly a foot below he knee ^ is difficult to designate one from the other on accoun of the intermineline ofthe fibres* However, the tendons of each, are distinct. NoTmKnt vessels or nerves are exposed on the skin :-on the opposS side, however, they are to be found, safely protected by muscles, bones and lascia. 106 ANATOMIC.* Name. Tibialis anticus. Tibialis posticus. CLASS BOOK. Arises from The upper and fore part of the tibia. The back part of the tibia, interosseous ligament, and ad- jacent part of the fibula. Fig. 50. ANATOMICAL CLASS BOOK. 107 Inserted into Use. The os cuneiforme inter- To bend the foot. num. The middle cuneiform bone, To move the foot inward. and upper part ofthe os navi- culare. Explanations of Fig. 49. q. The plantaris. r. The popliteus. s. The soleus. t. The biceps, forming the outer hamstring. «. it. The semitendinosus and semimembranosus, forming the in- ner hamstring. About the knee and ankle joints, professional bone-setters have played, and are still playing, a high handed game of quackery and imposition. On that account, therefore, it ha3 been an important object, to embody as much general information, in relation to the anatomy of the lower limbs, as possible, and at the same time avoid writing a professional essay on the diseases and incidents to which they are particularly predisposed. Three bones, only,enter into the composition ofthe knee joint; yet in this land of common sense, indi- viduals injure the articulation, and have it made well, by the reduc- tion of six or seven ! The ankle joint, made up entirely of three bones, — is often cured by having several Utile bones thrust into place! In the immediate neighborhood of these joints, a multitude of tendons have been seen', in the preceding diagrams, on which their perfection depends. By a thousand accidents to which they are ex- posed, the tendon of a particular muscle may be so prodigiously strained as finally to become inflamed. No pain is more severe nor more tedious in point of duration, than sprains — or over stretching of the tendons and ligaments. Though slow to feel, — when once roused, they are as difficult to manage as the bones, because they possess a vitality so low and so far removed from the sensibility of the soft parts, that remedies are a long time in effecting a restoration. To an inflammation therefore, and not to the out-of-joint condition of the little bones, is to be imputed the cause of protracted lameness in a majority of cases. The metatarsal bones of the instep are not thrown out of place once in a hundred instances where it is supposed they are. To youth, these remarks are addressed. 108 ANATOMICAL CLASS BOOK. Name. Peroneus longus. Peroneus brevis. Extensor longus digitorum pedis. Extensor proprius pollicis pedis. Flexor longus digitorum pedis, profundus, persorans. Flexor longus pollicis pedis. Fig. 51. Arises from The head of the tibia, and upper and outer part of the fibula. The outer and fore part of the fibula. The upper part of the tibia, interosseous ligament, and in- ner edge ofthe fibula. The upper and fore part of the tibia. The upper and inner part ofthe tibia. A little below the head of the fibula. Explanations of Fig. 51. f. The external plantar artery. g. The internal plantar. h. The tendon of the flexor longus pol- licis. i. The tendons of the flexor longus digitorum. t j. j. The massa carnea Jacobi Sylvii. i k. k. k. The lumbricales. MUSCLES CHIEFLY SITUATED ON THE FOOT. Extensor brevis digitorum The upper and anterior part pedis. of the os calcis. Flexor brevis digitorum pe- The lower part of the os dis, perforatus sublimis. calcis. ANATOMICAL CLASS BOOK. 109 Inserted into The metatarsal bone of the great toe. The metatarsal bone of the little toe. The first joint of the small toes by the four tendons. The convex surface of the bones ofthe great toe. The last bones of all the toes, except the great toe, by four tendons. The last bone of the great toe. Use. To move the foot outward. To assist the peroneous longus. To extend the toes, and separate them from one ano- ther. To extend the great toe. To bend the last joint of the toes. To bend the great toe. Notwithstanding the multitude of bands, muscles, cords and ves- sels were not ffr the broad sheet in the sole of the foot, reaching from the heel to the roots of the toes, like the sole of a shoe al the Mrts we have been considering would have been inadequate to its securiTy The plantaris, the name of this ligament, binds the arch the "foot, and* effectually prevents the bones from bjnj -pre^d anart and at the same time constitutes a firm external delence tor Se muscles, nerves and vessels. A similar broad ligament exxsts in . the palm of the hand, for the same purpose. MUSCLES CHIEFLY SITUATED ON THE FOOT. The first bone of the great and other toes, except the little. The second phalanx of each of the small toes, by four ten- dons, which are perforated by those of the flex. long. dig. ped. To extend the toes. To bend the second joint of the toes. 10 110 ANATOMICAL CLASS BOOK. Name. Lunibricales pedis. Flexor brevis pollicis pedis. Abductor pollicis pedis. Abductor pollicis pedis. Abductor minimi digiti pe- dis. Flexor brevis minimi digiti pedis. Transversales pedis. Interossei pedis interni. ~) Interossei pedis externi. S Arises from The tendons of the flexor longus digitorum pedis. The fore part of the os cal- cis, and external cuneiform bone. The inner and lower part ofthe os calcis. The ligament extended from the os calcis to the os cuboi- des. The tuber of the os calcis, and metatarsal bone of the little toe. The root of the metatarsal bone ofthe little toe. The ligament connecting the bones ofthe tarsus. The metatarsal bones. Fig. 52. Explanations of Fig. 52. /. The plantar arch, m. The flexor brevis pollicis. n. The adductor pollicis. o. The flexor brevis minimi digiti. p. The transversalis pedis. q. The interossei. r. The long ligament of the calcis. s. The tendon of the peroneus longus. —p ANATOMICAL CLASS BOOK. Ill Inserted into The tendinous expansion at the upper part ofthe toes. The first joint of the great toe, by two tendons. The first joint of the great toe. The outer sesamoid bone, or first joint ofthe great toe. The first joint of the little toe externally. The root of the first bone of the little toe. The tendon ofthe adductor pollicis. The metatarsal bones. Use. To draw the toes inward. To bend the first joint of the great toe. To move the great toe from the rest. To draw the great toe nearer to the rest, and to bend it. To draw the little toe out- ward. To bend the little toe. To contract the foot. C To draw the smaller toes < towards the great toe, and £ assist in extending the toes. 112 ANATOMICAL CLASS BOOK. QUESTIONS. Where are the ligaments found ? What is Syndesmology? Have the ligaments sensibility ? Are they elastic? Are there ligaments within the skull ? What prevents tha bones of the foot from separating, when we stand ? What do you understand by Myology. What is a muscle? What are the characteristics of a muscle. Their use ? What makes them red ? Have they nerves ? Are they all of the same figure ? How do muscles act ? How are muscles divided? Where are the involuntary muscles found ? Why does it require practice to play musical instruments ? Have the muscles a vitality which survives the death of the nerves ? Has each muscle an antagonist ? Are they ever relaxed? Do they ever become weary ? What is contractility, as applied to the muscle ? What are tendons ? ANATOMICAL CLASS BOOK. 113 Where are they found ? In cases of suspended animation, through the agency of what organs is vitality recalled ? How many muscles are there ? Are muscles always in pairs ? How many muscles from the elbow to the fingers ? What muscle raises the whole arm to a horizontal posture ? What muscle surrounds the eye, within the eyelids ? Has the nose any muscles ? Are there muscles connected with the external ear? What muscles bend the head forward, as in bowing ? What muscles assist us in walking ? What muscles are in action, in sounding the vowels ? What muscles sustain the upright position of the back ? What muscles extend the fore finger ? What muscle bends the fore arm on the arm ? What is the fascia and its use ? What muscle is the longest in man ? Are there muscles in the tongue ? Do muscles have any agency in modulating the tones ofthe voice ? By how many muscles is the eye moved in its socket ? What muscle rolls the eye downward, towards the shoulder ? What muscle lies over the back of the neck, like a tippet ? What muscle extends the whole forearm? What muscle rolls the fore arm to and fro ? What muscles constitute the calf of the leg? Where do the flexors of the toes run, to reach them ? What muscle enables us to blow with the mouth ? * 10* 114 ANATOMICAL CLASS BOOK. APPARATUS OF JOINTS. OR BURSOLOGY. Within the joints or in their immediate vicinity, there are small sacs, containing a glairy, oily fluid, which is poured out between the articulating surfaces, to prevent friction ; the name of this substance is synovia. Upon the same principle that any machinery is kept oiled, the joints are lubricated. When the secretion of the synovia, is im- perfect, or scantily effused into the joint, the highly polish- ed surfaces of the cartilages become rough, dry and sub- sequently inflamed. Even in the sheaths of the tendons, these oil bags are considerably numerous. A bout the wrist, elbow, shoulder, hip, knees, and ankle, they are large, but of various shapes, according to the space afforded them. Where the most motion is required, there are the largest sacs, secret- ing and throwing into the place, a copious quantity of the oil. A disease of the bursa mucosa?, which is the scientific name of the sacs, is familiarly known as the white swelling, — particularly of the hip and knee. It would not be profitable in a simple elementary trea- tise to dwell minutely on this subject. The few observa- tions here made, will satisfy the inquirer, that the care which is everywhere displayed in animal mechanism, de- monstrates in the most happy and unobjectionable man- ner, the contrivance of a Being antecedent and superior to ourselves. ANATOMICAL CLASS BOOK. 115 FLUIDS, OR ANGIOLOGY. THE HEART AND CIRCULATION OF THE BLOOD. It is one of the most curious facts in the whole range of physiological science, that the ancients were totally igno- rant ofthe circulation ofthe blood. By a long course of observations, it was commonly ad- mitted that there were in man, for example, two sets of tubes, which coursed through the body, and they assigned to each many absurd and ridiculous functions. As one set of vessels were superficial, directly under the skin, filled with the venous blood, which quietly moved along the smooth duct, —from some unknown point, to another, equally obscure, they were fully satisfied that it belonged, in some way, to the body. On the other hand, by various accidents, they had frequent opportunities of viewing the deeper seated vessels, throbbing and getting blood in recent wounds: — but as the color of their con- tents was different from that in the veins, and the activity that was manifested by these tubes, when exposed to their astonished vision, altogether different from the motionless, well behaved veins, the idea was at once admitted that these, which were denominated arteries, constituted the laboratory of the animal spirits, —or, in other words, it was in the arteries that ihe powers ofthe soul were gene- rated, in combination with atmospheric air, which found - its way into the reservoirs of life, through the puffing and blowing exercises of the lungs. When the artery was cut, 116 ANATOMICAL CLASS BOOK. and the warm blood was forced out by strong pulsations, then the spirit within was angry, — and so vented its displeasure and spite, like a snarling child, by spirting out its own precious self through the incidental aperture. Upon notions as rational as these, learned men con- structed some of the strangest theories that ever beset the imagination. When the whole subject of the use of the arteries and veins were supposed to be clearly understood, those sage investigators of the sublime and beautiful, rested from the weight of their labors, and, subsequently, established certain doctrines, which held a despotic sway for centuries ; yet they were as far from truth, as possible, — and worse than all, no person of common sense dared to call them in question. Who but a blockhead would ever have entertained a notion like this, viz. that the blood ran out from the heart through the day, or while one was awake, and returned again at night, when the individual retired to his slumbers ! Who but a profound dunce would have suggested the novel theory that weariness, the sensation of being tired, was in consequence of being so long awake, that the blood had all run out from the fountain head : — and when one could not move any longer, from complete exhaustion, why nature indicated at once what was to be done:—only lay the poor sufferer on a bed, the recumbent posture being highly favorable, the blood immediately took a downhil direction, and when it had all reached home, and was snugly settled down in one of the chambers of the heart, the tendency to death was suspended,— the man recov- ered his accustomed strength, and bright and early the next morning the same truant blood was ready to travel over the old ground again ! Thus it will be plainly understood, that the arteries were expressly set apart as a habitation for the spirit or vital principle : the veins, because they were less noble, were ANATOMICAL CLASS BOOK. 117 on the outside, while the others within, were exclusively appropriated to the to and fro, night and morning cir- culation of the blood. Another discovery, equally surprising, and iii exact keeping with the foregoing arrangement, related to the heart. They saw a little thing carefully boxed up in the chest, between the right and left lung, which to all intents and purposes satisfied the student of nature, that it was very hot, or it would not have been confined and sur- rounded by two great bags of wind : — it was kept tolera- bly cool by constant respiration ! The heart being decidedly a hot affair, there was a grand field for exclaiming and proclaiming the wisdom of nature, in providing such a delicate and at the same time simple, but perfect contrivance for keeping down its temperature below the boiling point! It was laced up in a straight jacket, — the pericardium, vulgarly called heart-case, of a texture so firm, that it was as self-evident as that the earth was the centre of the solar system, that this organ was liable to prodigious paroxysms of rage, and would burst from its prison, were it not thus secured. Two points were thus satisfactorily settled : viz. that it was very hot, and very unruly. Again,— within, there were certain apartments, which look the sensible and significant names of auricles and ventricles, — because the walls ofthe one bore some fanci- ful resemblance to the ears of a dog— but which, by the way, bear just as much resemblance to the horns of the new moon ; and in these cavities certain curious opera- tions were going on, which none but very wise philoso- phers understood. These consisted in the mixing of air and blood,—the instantaneous development of certain matters and things which constituted life, and gun-powder like explosions, consequent upon the ingress of cold air in the furnace ofthe heart. 118 ANATOMICAL CLASS BOOK. In reality, had those investigating geniuses ofthe olden time, whom it is so fashionable to admire, so classical to praise, known anything of the modern properties of the steam-engine, it is altogether probable they would have had much to say on the heart's property of generating power by converting its liquid contents into vapor, and, in the sequel, laboriously explained the causes which oc- casionally oppressed, — which clogged the wheels of vital action, and which, in plainer language, sometimes burst the boiler. We have merely sketched an outline of the general views which were entertained of the physiology ofthe sys- tem by the ancients ; — views it would seem, so absurd that the reflections of a school-boy would have overturned them : yet, strange as it now appears, they were carefully trans- mitted from one generation to another, for many centuries, and treasured up as the profound discoveries of antiquity. THE HEART. It would seem, at first view, from the high office of the heart, so constantly found in all animals with which we are familiar, that no organized being could possibly exist without it. Strange, however, as it may appear, there are various classes, in the lowest orders of animal crea- tion, which are totally destitute of it; still, they have blood, and that can under no circumstances be dispensed with,— but is not propelled by one single organ through the ves- sels. There is a compensation, however, in the structure of the primitive vessels, — or to be understood, a blood- vessel takes upon itself all the functions of a heart, ex- erting by successive pulsations, a power adequate to the physical requirements of the body in which it is found. Numerous, indeed, are the insects and vermin, in ANATOMICAL CLASS BOOK. 119 which this kind of organization is discoverable. But it is not an organization favorable to longevity,.for those in which this simple apparatus exists, are the beings only of a day; they flit in the sunshine a few hours; the object of their creation is attained, and they die. A resemblance to this sort of machinery is noticed in fishes; though they have a heart, it is exceedingly imper- fect, when compared to the same organ in warm-blooded animals. Fi". 63. Explanation of Fig. 53. A ) are the fringes of the gills, attached to half hoops of cartil- age ' These threads, which are of a bright red, are the extreme terminations of the branchial arteries; in an animal breathing air,— the same vessels are called bronchial arteries. B the ventricle of the heart, or forcing-pump, which drives the blood with which it is distended, into a single artery. Just beyond B the artery D divides into two branches, leading to the gills on either side, in equal quantities. Precisely like this is the right heart of man. Instead of being thrown into gills the branches di- rect the blood into the lungs. C, the auricle, or first receiving cav- ity of the heart. All the veins of the body in all animals, whether belonging to the land or water, ultimately unite into one tube, and that empties its blood into the auiicle. _ E in this diagram, E is the branchial vein, of the right gill soon united to that from the left side The blood has been changed in the Kills where it was sent by the heart, by being brought in contact with the air in the water, and now being fit for the purposes of the system, is returned by these veins, to a great vessel, lying under the hack bo tic F This is the reservoir of the revitalized blood : —at its com- mencement in the gills, it is like a vein, --but the main trunk now assumes the functions of an artery, or indeed a second heart. It contracts and propels its contents over the body. Here then is a tube taking upon itself the office of the left heart of land-dwelling ani- mals. 120 ANATOMICAL CLASS BOOK. Were it profitable, reference might be made to very many curious modifications of this blood-propelling apparatus, so positively neces- sary to the existence of all organized beings, in the oyster, cuttle- fish, birds, lizards, serpents, tortoises, frogs, tadpoles and some other reptiles. Indeed, the fish has but half a heart. All their blood, — and in some of the huge monsters of the ocean there is a prodigious quantity, — is sent its rounds by an artery, and not by a heart or any particular part of one. Here we perceive that a force is exerted by the contractions of a single vessel, equal, (for it must he in sharks of thirty feet in length,) to a moderate sized fire-engine. We positive- ly know it to be so, because the blood, by each pulsation, is driven through as much space in a given time,- as the water is thrown by the piston of the engine. In the mammalia, that is, animals breathing air, the heart is the centre ofthe circulation — the point from whence the blood starts, and the instrument of propulsion, by which it is kept going in an endless round, in the body. It is a forcing-pump, by which a column of fluid is raised, and an imitation of its mechanism may be examined in every house in which one of those convenient machines is used for filling tanks in the upper apartments. One is self-moving, having incorporated within its own substance, the wonderful power of generating physical strength ; while in the other, an extraneous force must be applied, some- where, to put it in motion. Surely the most sceptical must acknowledge in this in- stance, and it is only one of many millions which might be cited, that the work of an Almighty Being is here most certainly manifested. How simple the contrivance yet how astonishing the results ! ' In warm-blooded animals, the heart is a compound en- g.ne. If we go back to the fishes it is there single • but in man, quadrupeds and birds, it is double : they have two hearts, and both of them are forcing pumps. Man has ANATOMICAL CLASS BOOK. 121 two hearts, but they occupy less room by being joined to- gether, though, for aught we can discover, the system could be just as well supported, had one of them been placed at one side of the chest, and the other at another part. By being united less substance is required ; sym- metry is preserved, and the union of the two actually con- duces to the greater muscular power of both. Fig. 54. Explanation of Fig. 54. Bv this engraving, the reader will readily understand what we mean by the two hearts of man, and other warm-blooded animals, as thev are here exhibited, and as they appear when dissected apart. Each one of them is a perfect organ, by itself, and the one is per- fee ly dependent of the other. That having the leUer b upon it s the right heart,-and that with a g, the left. This 11 a front v'ew or Hke look ng into the chest of another person. The right heart is the engine of the Zung*,-for it supplies those organs ex- cfusivelv Th! left heart throws the blood, as a ready remarked in the text round the curve above g, in the direction indicated by the ^^VrlThe'cTasror'^eat veins, - returning blood.from the head and arms, and lower extremities. The uppermost is thesu- perior vena cava, and the one below, the inferior vena cava. Jhe Kws show the direction of the returning currents of venous blood, ™ the auricle, which forces it into c, the ventricle, which again forces it up into a, the pulmonary artery, where it divides, to go to each lung ; e, is one of the/our pulmonary veins which convey the nloou us? forced into the lungs, into the auricle f, of the left heart. When "hat contracts, it drives its blood into g, the ventncle, which, in its turn, forces it onward again into the arch, or the aorta, the 11 122 ANATOMICAL CLASS BOOK. main pipve, where it glides along in the direction of the arrow, di- viding into smaller streams on its way, and finally goes down the descending aorta h, to supply the body below. There are many animals which have only the right heart, but none that possess the left one alone. The fishes heart, in the plan preceding this, is the single, equivalent to the right heart of man. That there might be no interference, no irregularity, but perfect order and harmony, only one acts at a time. The right heart rests while the left moves, and then, in perfect obedience to a law which cannot be explained, operates in its turn. In configuration, the heart has no such vulgar shape as we are told in some of the books, like the ace of hearts on a playing card. It is a short cone, lying obliquely across the breast, the point of which beats, when in an erect posture, between the sixth and seventh ribs of the left side. Within, there are four apartments, so irregularly shap- ed, that they cannot be likened to anything. Each heart has its two cavities, communicating with each other by an orifice, about an inch in diameter, but a complete valve is suspended on the margin of the opening, like a gate, to close it, that all communication may be instantaneously interrupted, as we shall ascertain to be indispensably necessary, at each pulsation. Moreover, to prevent the heart from ever being over distended, from having its walls put too much upon a stretch, little cords of astonishing tenacity, run from one side to the other crossing and re- crossing each other in all directions, which also assist, by contracting, to squeeze it, as it were, together, in forcing out its contents. To secure it still farther, guarding against all contin- gencies, the heart is enveloped in a tough, slightly elastic case. Having this support, were the internal straps to be rent from their attachments, the swelling heart would be met from without, by its covering, and prevented from being ruptured by the accumulation ofthe blood within. ANATOMICAL CLASS BOOK. 123 Lastly, that the freedom of motion might never be abridged, the heart is suspended at the top of the chest, by its own tubes, being at liberty to swing in the triangular space given it between the lobes of the lungs, according to the various attitudes the body assumes. This is not all; the heart constitutes a hollow muscle, being as com- pletely flesh as the muscles of the arm. Besides, it pos- sesses all the essential characteristics of every muscle, the inherent property of contractility. Having explained the fact that there are two hearts, it is now necessary to show the necessity of this arrange- ment, which is no easy matter, inasmuch as we are to adapt our demonstration to the capacity ofthe young. Throughout the system there are two sets of lubes for conveying blood; —one conducting it through the body, and the°other returning it. To be serviceable to the system, which is the final cause of the elaborate machi- nery under consideration, two other important organs must necessarily claim attention, viz. the stomach and the lungs. In the former, the food is converted into a milky liquor, from whence it is actually conveyed into one ofthe cavi- ties of the heart; but before it can be of any service, it must first be mixed with that already in the veins. A chemical change is effected in it by being exposed to the action of the atmospheric air, that makes it blood. As the first process is completed, the next object nature has in view, is to distribute it, and the left heart is the apparatus by which it is effected. There is no communi- cation between the cavities ofthe two hearts, but we per- ceive that the blood which is pouring into the right side, must be thrown somewhere, and as it cannot go,into the left where, the query will arise, does it move ? — directly into the lungs. From thence it is collected, and by four branching tubes carried to the left heart. Thus, the left 124 A.NATOMICAL CLASS BOOK. heart forces it in all directions from the centre, and the right heart forces that which has been returned into the lungs. By an untiring labor of the two hearts, acting alter- nately, from birth till death, the blood, that important sub- stance, on which life depends, is kept always going and coming, and whatever property or quantity is lost on the loule, is supplied by the activity of the stomach, the great laboratory in which the material is manufactured of which it is originally made. Authors detail the particulars of what they call the two circulations, — viz. the greater and lesser, by which is to be understood, that the right heart and lungs constitute this lesser, because the force of the engine is only exerted to throw its contents into the air cells ofthe lungs. On the other hand, the greater circulation, means the left heart and all the arteries leading from it, quite to the ex- tremities. As the power to be exerted by the left heart, in order to-throw the blood the entire length ofthe body, is vastly superior to its fellow, which is only required to push its volume of blood about ten inches, so it is proportionably stronger in its substance ; thicker in its walls, and more sensitive to the application of stimuli. In the act of dying, the left heart invariably clears all its cavities, — and there- fore is always empty on dissection, but the right heart re- mains full and burthened. ANATOMICAL CLASS BOOK. 125 Explanation of Fig. 55. The double heart of man : - q, descending vena cava; o, ascend- JvenaTava; n, right auricle ; b, right ventricle ; k, pulmonary arteru I I, r\ing all the blood from the head, and brain, ami arms, into the auricle of the right heart. The jugular veins, llierefoi <-, are the great veins of the brain, and commence behind the forehead bo..e, just between the eyes, within the skull. At the last joint of the spine, the lumbar region, we left the descending artery, divided into two branches. In as- cending from the heart, the large artery is called the as- cending aorta, and having made the curve, the descend- ing tube is the descending aorta. These two trunks, now lying just within the brim ofthe pelvis, divide again, sending a supply of blood to the muscles and apparatus within the pelvis. The first trunks are the exlirnal iliacs, and the second set are internal iliars. Further down, in the thigh, in each limb, the arteries appear under the name of femoral arteries : — in the ham, behind the knee joint, the popliteal; still fur- ther, by the side of the shin bone, the tibial; in the foot, the planter, and so on, till the divisions become too minute to be discernible to the naked eye. Between the arch and the pelvis, various little twigs are thrown off laterally to nourish the lungs, diaphragm, 140 ANATOMICAL CLASS BOOK. liver, stomach, spleen, and other abdominal viscera, — each bearing a name indicating its destination, or office, or supposed resemblance to familiar objects. Here, then we have exhibited a scheme of the arterial system, per- haps quite as well as to have accompanied the text with many more drawings. The arteries must be nourished themselves, by a free circulation of blood in their coats, as much as the heart; otherwise, were they independent of the rest of the living body, they would be extraneous, and could not contribute to its wants. On the sides of all the arteries, millions of vessels, infinitely fine, more nearly like the down on a peach than arteries, conduct a circulation. This tissue or net work of miniature arteries, is the vasa vasorum. Finally, the arteries are made up of several coats, as though one tube were thrust into another, — which are muscu- lar and membraneous, according to their importance. As they recede from the heart, the tendency is to keep subdividing/to supply every possible part, — hence, ulti- mately, they become too small to be seen. Between these points, and the commencement of the veins, is an inter- mediate set of real or imaginary vessels, the capillaries, through which the blood must pass to reach the vein3. Such is the monstrous size of the aorta in a whale, that the whizzing velocity of the blood, at each systole, is audible to the harpooners: with the stethoscope, quite a modern invention, the rush of the blood may be heard in our own species. ANATOMICAL CLASS BOOK. 141 Explanation of Fig. 61. It is utterly impossible as well as unprofitable, in an el- ementary work of this kind, intended for youth, to pfcture every vessel; but we were desirous of displaying the ar- teries of the arm and palm of the hand, on account of the beauty and great importance of the structure. What is seen in this drawing, exists in every living arm. Over the bend of the elbow, a mere web lies between the great artery and vein. The vein is taken away, but it will show how dangerous it is to bleed the vein, at this point, on ac- count of the nearness of the artery, which is liable to be wounded by the point of the lancet. A knowledge of this fact, should deter every one from employing surgeons in whom they have not the most Implicit confidence, that they understand anatomy, a, b, c, d, e, f, g, h, k, mark the branches ofthe brachial artery a, as they are, in relation to the muscles ; i is thefassia or the membrane, between the artery and vein, and which is a tendinous strip sent off from the biceps flexor cubiti or bending muscle of the fore arm, as though it was express- ly designed to confine the throbbing artery in its place, and protect it from the injuries to which it seems liable by carrying burdens in the arms. This strip of tendon is like the arch of a bridge, — for if the arm is bent, it is still tense, and therefore always a de- fence. This brachial artery, near the elbow, divides into branch- 142 ANATOMICAL CLASS BOOK.-; es; —one of them sinks into the muscles, to supply them, by the side of the ulna, on a line with the little finger, and hence called the ulnar artery. The main trunk of the brachial, however, travels downward, quite superficially, near the edge of the radius, and therefore has the name of radial artery. In the wrist, being just under the skin, it is pressed against the bone, where its pulsations are felt: — feeling the pulso, in the language of physicians, simply means the sensation conveyed by the throbbings of this artery, when thus compressed. Further on in the palm of Ihe hand, it forms half a circle, termed the palmer arch, and from its outward curve, digital branches convey the blood to the fingers and thumb. That the arteries possess the property of contracting upon the blood cannot be denied. The heart, were it in- tended to force the column, independently of any assis- tance from the arteries, through their whole extent, we should suppose, was not adequate to the undertaking, be- cause the proportions are unequal, in comparing the engine with the distance to which it is required to send the blood. The pulsations ofthe arteries, indicate that they continue and propagate the action which was commenced by the heart. Were it not so, of what use are the valves at the mouth ofthe aorta and in the pulmonary artery ? If the volume to which an onward impetus had been given, could pur- sue the tortuous windings, quite to the capillaries, of what need were the valves ? The truth appears to be this, viz., the ventricle only throws the blood beyond the valves, which are thrust across the canal to prevent a regurgita- tion, and then the artery compresses it in turn. Onward it moves, to some other place, where, before the velocity that has been given it is lost, a second, third and fourth pulsation, as the case may be, conpletes the circle of ac- tion. Do we not actually feel that the artery pulsates in the wrist; and do we not also recollect that in the fish, an artery, the aorta, assumes the office of a heart; in the vermin too, did we not show that the aorta and accompa- nying arteries carried on the perfect circulation, without any heart at all ? ANATOMICAL CLASS BOOK. 143 The arteries are not passive tubes, imbedded in the concealed interstices of the muscles to conduct a fluid in which they have no part nor interest. They are not qui- escent, like the wooden pump logs of an aqueduct corpo- ration, remaining at rest, till something disturbs them : — no ; they are portions of a living whole, endowed with a vitality which results from this peculiar combination of or- ganized matter. They feel the vigor, or the decay of other parts ; they become diseased by over excitement; sicken, refuse to pursue their accustomed service; and when the crazy, shattered frame ofthe old man begins to tottle, the arteries, too, begin to flag, and finally cease to act at all. In old age they ossify — becoming perfectly bony tubes, for many inches together: by over action, they are en- larged into irregular sacks, or aneurisms ; and in ad- vanced cases, they burst, and the heart's blood is wasted so quickly, that life may be said to have exploded. The tendency of age, is to relax the muscular fibre, and in this general debility, the arterial coats suffer — their diameters enlarge, and their power is diminished as their transverse diameter increases. The energy of the pulse is lost; the arteries, however, make an effort to sustain their accustomed vigor, by assuming a more tortuous course, — showing, that the short curves which are made under these circumstances, are favorable to the accumula- tion of physical power. VEINS. It is much easier to account for the propulsion of the blood from the heart, through the arteries, than to explain the process of its return through the veins. Their origin is in the capillaries, quite at the extreme terminations of the arteries, growing larger as they advance towards the centre of the body. They are seen through the skin at the ends of the fingers, on the arms, and indeed every- 144 ANATOMICAL CLASS BOOK. F\g. 62. Explanation of Fig. 62. The anatomy of the veins being much less intricate than the arteries, to understand, it has not been thought h necessary to present more than one i plan of some of the most superficial y vessels of this order. On the calf of the leg, there are g numerous veins, just under the skin, uniting into fewer and fewer branches, as they rise upon the limb, till they "■ finally unite in two principal trunks, one deep seated, and the other super- ficial, which pass into the pelvis, at the groin, and thus convey the blood to the ascending vena cava, the great vein that carries all the blood to the heart, which has been collected below it. By turning to the drawing of the double heart, Fig. 2, that great vein will be seen. d. The gastrocnemius. e. The nervus saphoenus minor. f. The branch arising from the pop- liteal. g. The nervus communicans, aris- ing from the fibular nerve. h. The popliteal nerve. i. The fibular nerve. k. The popliteal vein. I. The vena saphama minor. m. The popliteal artery. n. n. The arteriae, distributed upon the calf of the leg. p, p. The muscles on the back of the thigh. d. The gastrocnemius. where, creeping upward, becoming increased in size at every step, trll they eventually are reduced in number to two principal trunks, the superior and inferior cavas, at the right auricle. Their coats, which are the same as the arteries, are thinner and weaker — more dilatable, and consequently much oftener diseased and liable to acci- ANATOMICAL CLASS BOOK. 145 dents. Through their whole track, with a few excep- tions, there is a line of valves, the office of which is to hold the column from falling back, that has once passed above the lock. So frequent are these valves, that they may be detected every inch, in the great veins ofthe arms. By compressing the vessel above one of them, the blood at once accumulates in the form of a knot, — showing ac- curately the exact place of its locality. The principle of fixing a ligature round a limb, as a preparatory step to bleeding, with a lancet, is to stop the blood in its course,— there being no possibility of its going backward, as it is held by the valve,-—therefore, as the canal is closed by compression above, the escape is at the incision. We will not pretend to inform our readers how the blood travels up the veins, — lying, as they do, perfectly quies- cent. It seems as though there must be a propulsive force exerted somewhere in the vicinity of the capillaries, to thrust the blood along, yet dissection gives us no clue to the mystery. The veins also perform other interesting duties, acting as absorbents, accompanying the arteries, wherever they may go, to be servants in waiting,-—to pick up, and carry home whatever may have been conveyed to a distance by their superiors. CIRCULATION OF THE BLOOD. Were it not necessary in the plan of animal life to pre- sent every particle of blood, at certain intervals, to the influence of atmospheric air, there would have been no need of a heart. We might have been born with a suffi- cient quantity in our bodies, where it might have remained undisturbed, fulfilling the intentions of its design. Such a state of things, however, is not admissible, because it is secreted into the vessels to increase the growth, to repair 13 146 ANATOMICAL CLASS BOOK. the wastes, and to sustain the whole by its vivifying pres- ence. Every bone, muscle, tendon, nerve, membrane and fluid, is made out of the blood. As the parts to be made cannot fabricate themselves, and afterwards take their ap- pointed stations, the blood goes to the spot where this is to be effected, leaving material for a bone in one place, glue to hold particles together in another, and so on, in its ac- tive round. But, on the other hand, these particles can- not fashion themselves : — the point of an artery, there- fore, at which they are given off, assumes the office of an artisan, and moulds and finishes the work. We here discover that the arteries possess a wonderful property, which was not spoken of in the preceding para- graphs. Industrious and unerring in all the first years of life, invariably conveying just the sort of material that may be wanted to mefid a broken bone, to heal a cut finger, or to lubricate a joint, they grow careless in forty years: — they neglect supplying the eyes with sufficient quantities of humors to distend the ball, so we meet the emergency by wearing spectacles: they are forgetful of the order by which their early labors were regulated, — and as one mistake leads to the commission of another ; lime is car- ried to the heart, where the valves become bony ; the urinary apparatus is carelessly watched, and stones form in the bladder; the teeth are not supplied with earthy matter in season to prevent their decay : — the hair is not watered at the roots, and it becomes dry and falls off. Such cursory remarks as these, exhibit a bird's-eye view of the importance and multifarious functions of the arte- ries, and demonstrates the high value of the blood, from which so much and such inimitable machinery is formed. As we now comprehend the use of the circulation, we will next endeavor to solve another apparently difficult problem — the why it is necessary to throw the blood into the air cells of the lungs. ANATOMICAL CLASS BOOK. J 4? Explanation'of Fig. 63. It" the student is desirous of thoroughly and clearly understanding the circulation of the blood, as it moves in his own body, let him now recapitulate the subject, by following the venous or black blood from the two great supplying veins, till it arrives in the main dis- tributing artery, purified, re-vitalized and in a condition to sustain animal life. . ,,,.,,*■ »i. u < q, the descending vena cava, returning black blood from the neact and upper extremities. _ o, the ascending vena cava, returning the same kind of blood trom the lower parts of the body. n, the right auricle ofthe heart, where both veins meet. p, and x, veins from the liver, spleen and bowels, uniting with the inferior cava. The auricle being filled, contracts and forces the blood into 0, the ventricle: next the ventricle contracts and sends it into k, the pul- monary artery, which branches into I, I, to supply the lungs in both sides of the chest. From'the lungs, where a scarlet color has been given it, four veins of the lungs gather it together, and deposit it in the left auricle r; that contracts, and the blood is driven into the left ventricle a ; lastly, the ventiicie contracts and throws it into c, 14S ANATOMICAL CLASS BOOK. the aorta, which conducts it over and through every bone, musxle and organ. Under a solar microscope, the circulation of the blood m the tnin web of a frog's foot, and several other reptiles, may be distinctly ob- served ; and in insects, while they remain worms, the pulsations of the artery which acts instead of a heart, are readily perceived. In the oyster, the heart pulsates about thirty-seven times in a minute. Before birth, the blood, instead of going from the auricle of the right heart down into the ventricle, to be thrown into the lungs, passes directly through a valve in the partition wall between the two auricles, and thus gets into the leftside or left heart.' The reason why the blood is not sent to the lungs, is because they have not yet assumed the function of breathing. At birth, when the first breath of air is inhaled that ever entered the lungs, the valve closes up the opening forever, and the blood then takes a circuitous route through the lungs, for the reason which has been already so familiarly ex- plained. The sign of the vitality of the blood is its scarlet color? which it only exhibits in the heart and arteries. When it goes from the heart, it is charged with the presence, or admixture, of every material which can possibly be re- quired; but on its way to the capillaries, all these several materials, supposed to be in solution, are dropped on the way, so that when the refuse, that is, the fluid, which was merely the medium of conveyance, enters the extreme be- ginnings of the veins, its color is almost black. Having, therefore, imparted all its needful qualities, it is totally unfit to be sent round a second time, till it is re- charged. To obtain this quality, now lost, the right heart sends it into the lungs. Surrounding each distended air cell, is a thin sheet of black venous blood, which by the mysterious influence of the contained air, changes the color, instanter, to its original scarlet. The orgasm, the suddenness ofthe change, cannot be conceived — yet the whole mass is re-vitalized, and is now carried into the left heart, to be again sent over the old ground. Such in familiar language, is the circulation of the blood — a pro- cess well calculated to raise our admiration for the charac- ter and transcendent power, and condescending goodness of our Creator. ANATOMICAL CLASS BOOK. 149 Anatomists in treating of this important fluid, speak of its being composed of three substances, viz ; serum, the watery, yellowish fluid ; fibrin, the crassamentum, or cake; and the coloring matter. Were we not restricted in this work to certain limits, it would certainly be an entertain- ing theme to detail the extravagant whims which the old authors entertained upon the subject ofthe red globules of the blood. It actually seems, to a calm spectator, who surveys the past and compares it with the present, as though the physiologists of the two last centuries bowed down to make themselves positively ridiculous, by the sweat of the brow. When, by some fortuitous circum- stance, it was ascertained that the florid hue of the blood depended on the actual pressure of floating globules, of different sizes, yet so minutely small as to appear like the coloring of an infusion, they set to work in earnest to in- vestigate their use and structure. About the same time, un- luckily, a philosopher invented the compound microscope, which enabled every body to peep into microcosms, where they beheld sights, quite imaginary in most cases, more astonishing than were ever before revealed to human eyes. Whether they saw distinctly or not, it is now of little consequence ; but at all events, they asserted the want of uniformity in the size of the globules, though each one was a hexagon, built up regularly and mathematically, as an architect could construct a country seat, of six smaller hexagons ! However small — and some where supposed to be immensely beyond the magnifying reach of their glasses— they were all framed in the same workman-like manner. All this fine discovery being settled and indisputably admitted — for it would have been outrageously impolite for those who had no microscopes, to call the marvellous discovery in question — their wits were in labor to devise a rank for them in the circulation. This, too, was accom- 13* 150 ANATOMICAL CLASS BOOK. plished; but to find out the diseases that originated in consequence of the mistakes, or refractory conduct of the compound balloons, was a poser. There is nothing, by the way, like perseverance. A man who is lost in a fog, has but one course to pursue, and that is to take care of himself: so it was with our discoverers; they had their mathematical bladders on hand, which must be disposed of— and here they are, in all their beauty of arrange- ment, from the plastic hands of their discoverers. Diseases were the effects arising from error loci — that is, some of the large globules, fitted to the calibre of a par- ticular artery, got wedged by some sad mishap at the mouth of a smaller vessel, or, becoming angry, refused to operate in the harness, so puffed up — clogged the pass- age — and this produced inflammation, out of the modifi- cations of which fevers, dropsies, and all the other ills that flesh is heir to, had a bona fida origin ! Enough has been written to stimulate our readers to the perusal of the old records of physiological folly, in the original tongue, if they wish for an uninterrupted history of that singular discovery. To those who are more inter- ested in the anatomical facts we have been relating, touching the heart and the arteries, it is needless to re- commend them to the writings of those who are teachers by profession. Perhaps we may have committed ourselves in the ardor of the moment, by advancing ideas quite as absurd as those which we have been condemning ; but in the demonstration of parts, we are conscious of being right, having given the anatomy of the circulation as we have found it, by years of toil; and as it regards theories, things made at little expense, like castles in the air, we are not tenacious about the respect that may be paid to them. Having been right merry over the conceits of our profes- sional predecessors, we are quite willing to be laughed at in turn. ANATOMICAL CLASS BOOK. 151 QUESTIONS. Had the ancients a knowledge ofthe circulation? How did they explain the movements ofthe blood ? What is the heart ? Is the heart a single or compound organ ? In what animals is the heart single ? Why is it necessarily single in fishes ? How does it act? How many cavities has the heart ? What prevents the blood from rushing into the wrong apart- ments ? Has it a circulation of blood for its own service ? What are the auricles ? What are the ventricles ? What is the use ofthe valves ? Has the heart any nerves ? Why has the will no control over it ? Where is the heart located ? Is it covered by any membrane ? Why are not the pulsations felt in the right side ? How does the right heart differ from the left ? What is an artery ? Where is the principal artery ofthe body found ? What veins return all the blood to the heart ? Are there valves in the veins ? Has the aorta any valves ? 152 ANATOMICAL CLASS BOOK. Where does the pulmonary artery arise ? Where are the carotid arteries ? By what arteries is the brain supplied with blood ? Is the heart a forcing engine ? How are the pulses perceived in the wrist? What is the use of the pericardium ? What change is effected on the blood in the lungs ? What color has the blood in the veins ? What color has the blood in the arteries ? Does blood circulate in the bones ? By what organs are all parts ofthe body fashioned ? Of what use is the blood in an animal ? How is the blood supplied ? What is the object of taking food into the stomach ? Is it known by what power blood is moved in the veins ? What is the composition ofthe blood ? Why are some animals denominated cold blooded ? Is the blood warm in reptiles having a single heart ? Can any animal exist long, deprived of its heart ? What is understood by the irritability of the heart ? ANATOMICAL CLASS BOOK. 153 THE NERVES, OR NEUROLOGY. Neurology teaches us the anatomy and physiology of the nerves. The brain is the radiating point whence the nerves, to a considerable extent, have their origin. The spinal marrow, from which an immense number of nerves branch out, is considered in reality by some, a prolongation of the brain itself. Phrenologists, on the other hand, sup- pose the brain arises from the spinal marro\v, because the brain is sometimes wanting, but the nerves are always present. In the first place, the contents of the head are divided into the cerebrum and cerebellum, or in other words, the great and small brains. Above the level of the ears, all the upper portion ofthe skull is occupied by the cerebrum, which is the immediate seat of intellect. Below that level, in the lower and back part of the head, is the cerebellum ANATOMICAL CLASS BOOK. Fig. 64 Explanation of Fig. 64. This is an exhibition of a vertical section ofthe bones ofthe head, face and brain, showing precisely the appearance, were the head di- vided in the middle, from the top, down to the neck. No letters of reference have been introduced, because the plate will be doubly valuable, when the general relation of the different portions have been learned from the text and the other diagrams. The reader will then trace with his eye the outline of the little brain, the cerebrum, or large brain, the seat of thought; the ventricles and other interest- ing points, which, though intricate, are nevertheless worth the trou- ble of understanding. The mechanical arrangement is only contem- plated in these illustrations: — the functions of the brain in a treatise, purely elementary, would be wholly useless. or little brain. They are separated from each other by a membrane, tensely stretched. Otherwise, the weight of the upper mass would oppress the functions of the lower one. By a vertical line, the brain is divided into hemi- spheres, as right and left; but when it is dislodged from the head, and inverted, the underside presents three promi- nent risings, which are denominated lobes. Those por- tions of the brain directly behind each eye, are the ante- rior lobes. Those at the back side of the head, the poste- rior; and the third, between them both, are the middle lobes. ANATOMICAL CLASS BOOK. 155 COATS OF THE BRAIN AND NERVES. In this plain exposition of the anatomy of the nervous system, it would be an endless labor to attempt a minute detail ofthe three different coverings, which surround the intellectual apparatus, independently of the bony box, the strong wall that envelops the whole. firm coat, or — Dura Mater. When the skull is opened, a dense, shining membrane is presented, lhat keeps the brain together, when the bones are taken entirely away. Completely embracing the entire organ, it becomes thicker round the medulla oblonga, to defend this narrowing of the brain, over the bones of the neck, — then continues its course through the whole length of the back-bone, embracing the mar- row : wherever a branch or side nerve is given off, a por- tion of the dura mater follows it, precisely as the bark of the trunk covers the branching limbs. In the still smaller divisions of the nerve, a continuous tube of the dura mater is found, till both are finally lost on the exterior surface. This membrane, let it be remembered, holds the office of defending the pulp of the nervous matter within its em- brace, wherever the nerves may traverse. transparent coat, or — Tunica Arachnoides. Perhaps there is not a more delicate, transparent mem- brane in the whole body than this, — so much resembling a spider's web, that from this circumstance it has its name. This lies over the convolutions of the brain, directly under the dura mater, and does not dip down between the pro- minences. Beside surrounding the brain, like the other, it has precisely the same infinite distribution — making the second tube for defending the nerve. 156 ; ANATOMICAL CLASS BOOK. soft coat, or — Pia Mater. Blood must be everywhere freely circulated; but in the brain, it is necessarily thrown into that portion which is the seat of thought, in very minute, hair-like currents, — otherwise the force of the heart, which acts upon the principle of a forcing-pump or syringe, would tear it to pieces. This pia mater, therefore, is an immense, broad, thin net of blood-vessels, following the fissures and wind- ing into the very centre of the brain, and also pursues the nerves, wherever they may go, always in attendance to furnish the vital fluid, on which health, sensibility, and, indeed, all the vital functions are forever depending. structure of the brain. The centre of the nervous system is the brain, within the bones of the head, with the exception of that class of animals, which, as it were, are the uniting links be- tween the vegetable and animal kingdom; — the worms are without it: fishes too, and amphibious reptiles have scarcely a development of the nervous mass, entitling it to the appellation of brain. We suppose, however, that we are contemplating the human brain, a singular, but splendidly constructed piece of mechanism, made up of an infinite congeries of "delicate cords, — and equally at- tenuated blood vessels. It was once thought that we had but one brain, but modern discovery assures us that we possess four ! and that two of them mutually cooperate, in function, with the others. There is no particular point where the brain can be said to begin, nor a point, in fact, where it terminates. Let the reader suppose that cm the first joint of the neck, just under the head, two large cords are lying, side by side : entering the great natural opening of the skull, they are ANATOMICAL CLASS BOOK. 157 subdivided into millions of threads, — portions of which assume different forms, to which anatomists give specific names, — as cruri, pons, &c. But as the threads are merely subdivisions of the one cord, — the mystery is, at first view, how comes such an increased quantity 1 noth- is more simple than an explanation. Admitting the fibres to be indefinitely long, — the folding and refolding of one upon another, in conjunction with an artery and vein — there is no difficulty in giving an answer. For the evi- dence of a fibrous structure, this infinite volume of threads, we refer to the positive demonstration of the brain by the late Dr Spurzheim. Most ofthe organs are double, and it was highly neces- sary that the brain should be so also. The great brain cerebrum, in the upper part of the head and over the eyes, is the immediate seat of intellect, and in halves; in other words, there is one on each side, divided, above from each other, in the middle, by a membrane. Under this, in the lower and back part of the head, is the cere- bellum, or litlle brain, belonging to the animal system, and totally different in function from the other; this too, is in two pieces. Below the point on the neck bone on which the two lateral cords, termed medulla oblonga, lie, extending with- in the bones, the whole length of the spine or back-bone, the same cords are seen — giving out, between the points, ribs, &c, branches, — called spinal nerves. Those within the client take the name of thoracic nerves; — still lower, between the ribs, intercostal, and still further down, be- tween the bones of the back, the lumbar nerves. The limbs of a tree, shooting out from the trunk, precisely rep- resent this part ofthe anatomy ofthe spinal marrow. Let it be remembered, that, from the head to the termi- nation of the spinal marrow, two cords, tieo brains, two little brains, and two distinct sets of lateral nerves exist 14 158 ANATOMICAL CLASS BOOK lying, however, in juxtaposition, intimately united by the decussation of fibres, which run from one to the other. This cerebral substance is so soft, that without its en- veloping membranes, it would fall to pieces, by its own weio-ht. These membranes possess but a very slight de- gree of sensibility; — being of a mealy whiteness, and in the skull possessing but little elasticity, though in the body and limbs, this quality necessarily exists, or they would become elongated and flaccid in the constant flexions of the extremities. Whilst this nervous matter preserves its vitality, it pre- serves a slight degree of cohesion, but after death, it speedily begins to decay, and ultimately melts down into an oily fluid. As before remarked, (.he composition ofthe pulp of the nerves and the brain, are precisely the same, in appearance, in life, and chemical analysis conclusively presents the same elements after death. When wounded, even badly, the brain feels no pain, al- though the very centre of sensation. It is not uncommon for portions ofthe brain to escape through fractures ofthe skull, and yet the person perfectly recover, and never suf- fer, in any quality of his mind, from the loss of this impor- tant corporal substance. Let it here be recollected that all the nerves which go from the head or spinal marrow, however much they may he distributed within the muscles, invariably run towards the surface of the body ; they do not, however, end in blunt extremities under the skin, like the cut end of a twine; — on the contrary, they are so infinitely subdivided, that the single cord which we find between two points ofthe spine may finally become a perfect brush, in the course of dis- tribution, and lost in the masses of flesh through which it travels, till it can no longer be recognised by the naked eye. ANATOMICAL CLASS BOOK. Fig. 65. 150 Explanation of Fig. 65. S the annular ligament which binds down the muscles and vessels to the ankle bone, to keep them in place. B, the extensor brevis digitorum, which assists in extending the toes. Fig. 1, superficial threads of the deep seated nerves of the leg and instep, emerging upon the top and losing themselves in the skin. Fig. 2, are long, but superficial cutaneous branches of the tibial nerve, sent into-the skin and cellular membrane at the root of the toes and ball of the great toe The trunk, from which these twigs have their origin, originated within the pelvis, yet, notwithstanding they were concealed, deep in the flesh the whole length of the limb, they finally make their appearance at the surface. This figure, therefore is designed to il- lustrate the position maintained in the text, viz, that all the nerves have a direction towards the external surface of the body. THE MECHANISM OF THE NERVES. As the brain, all experience proves, is the seat of intel- lect, so also, incontestible evidence teaches us that the nerves are parts which are susceptible of painful or pleas- 160 ANATOMICAL CLASS BOOK. urable sensations. Thus a piece of sugar is grateful to the gustitory or tasting nerves of the tongue ; — but to- bacco, before accustomed to its nauseating character, has a directly opposite effect. Pressure on the scialic or great nerve of the leg, by sitting too long in one position, pro- duces the disagreeable feeling, commonly called sleep in the foot; if, however, the attitude is not changed, to re- lieve the pressure, a partial palsy of the limb must ensue. Difficult as it is to ascertain precisely, the structure of the inner substance ofthe nerves, it is reasonable to infer, from analogy, as the substance is so exactly like that of the brain, that they are constituted of a multitude of mi- nute, soft, pulpy parallel cords. Instead of saying that the nerves have their origin in the brain or spinal marrow, they should be called the prolongations of the brain. Their internal substance, both physically and chemically con- sidered, presents the same results. They are the tenta- cular of the brain,—analogous to the feelers of insects, by which it takes cognizance of external things: — the instruments of the will, and the ever faithful sentinels at the outposts, giving the earliest and most certain intel- ligence of whatever is of consequence to the safety and well being ofthe individual. If they possess an organization like the brain, or in fact, are simply a prolongation of it, into the extremities of the limbs, the question may be asked why they are not con- scious, in their individual capacity — and why it is neces- sary to make reference to the superior mass of the same material, within the skull ? In the very lowest orders of animals, such is the case, to a certain extent: the worms are without brain, yet they pursue unvarying instinctive actions, and avoid enemies or caress friends, with as much certainty as those pos- sessing a well marked one. Nothing can be more perplexing, than the nerves, being ANATOMICAL CLASS BOOK. 161 of all sizes, from a quarter of an inch in diameter, to hair- like threads, invisible to the naked eye. Certain it is, that this apparent confusion presents the same appearance in all animals of the same species : Fig. 66. 14* 162 ANATOMICAL CLASS BOOK. Explanations of Fig. 66. MUSCLES. A. Pectoral muscle. B. Detoid muscle. C. Latissimus dorsi muscle. D. Serratus major anticus muscle. E. Biceps Flexor Brachii. F. Round tendon of the biceps, crossing the elbow joint. G. The broad expansion of the biceps, shooting into the fassia of the fore arm. H. Triceps extensor muscle. I. Bracheus internus muscle, an auxiliary to the biceps. K. Coraco Brachialis muscle, an assistant to the deltoides. L. Supinator Brevis muscle, turns the palm of the hand and fore arm forward. M. Supinator longus, operates in unison with the brevis. N. Extensor Radialis Longior, extends the fore arm. O. Many flexor muscles ofthe fingers, all arising from one point. P. Flexor digitorum profundis, bends the joint ofthe fingers. R. Annular ligament of the wrist, bending the tendons in a groove. S. Short muscles, forming the ball ofthe thumb. T. Flexor and abductor muscles ofthe little finger. n e r v e s . 1. 1. Radial nerve. 2. 2. Ulnar do. 3. External cutaneous nerve. 4. Musculai spiral nerve; supplies the flesh on the back side of the arm and skin. 5. A communicating twig. 6. Articular nerve, round the joint. 7. Internal cutaneous, supplies the skin under side ofthe arm. 8. External cutaneous, again; passing through a muscle, and then becoming a cutaneous nerve. 9. Branch ofthe external, going to the back of the thumb. 10. Muscular spiral nerve. 11. A branch ofthe external cutaneous. 12. The radial nerve. } ,.a ,o tu i } different views. 13. The ulnar nerve. ) 14. A branch ofthe ulnar, to the back ofthe hand. 15. Distribution of the radial nerve to the thumb, fore finger, middle and one side ofthe ring finger. 16. Distribution of the ulnar nerve to the other side of the ring, and both sides ofthe little finger. N. B. We have exhibited in this plate a mass of muscles and nerves, that the reader may have some idea of the complex machinery ne- cessary to the perfection of only one single limb. ANATOMICAL CLASS BOOK. 163 wherever there is a twig in one body, leading to an organ, precisely such another, fulfilling exactly the same office, may be demonstrated in another : a curious illustration of this remark is strikingly manifested in the nerves of the human hand. The arteries are not invariably constant, or undeviating travellers of a particular muscle. With the nerves, the case is altered: — they are constant, as it respects the origin, course and ultimate distribution — go where they may, a precise number of branches are required, to be dis- tributed to every portion and piece in which a blood ves- sel enters. Usually, the deep seated nerves accompany the arteries ; and the nerves of the skin keep in the track ofthe superficial veins. Though the nerve3 are small, and uninfluenced by voli- tion, exact order is preserved, or the same effects could not be produced in two individuals, from the same causes. Without nerves, there could be no sensation : — with- out them, neither painful or pleasurable emotions would be recognised; without them, organized beings would be completely motionless, without locomotion, and with- out perception or consciousness. It matters not how perfectly the muscles are developed, or advantageously arranged, if there were no mode of sub- jecting them to the influence of the brain, —they would be of no kind of consequence. Were the nerves in the wrist divided, the ability to clench the fingers would be lost; nor can it be recovered, unless a re-union ofthe divided portions can be effected. These are the voluntary nerves. Those denominated involuntary, administering to the involuntary muscles, are equally important to the hidden regions in which they are found. When the breathing nerve of the diaphragm is separated, the midrif no longer renders assistance in respiration. The muscles of the 164 ANATOMICAL CLASS BOOK. chest are compelled to carry on the process of breathing entirely alone. By dividing minute twigs, as they creep into the vocal box of a dog, the muscles are paralyzed, and the animal can never afterwards bark. Digestion in the stomach may be interrupted by cutting the main trunks of the nerves. Even the functions ofthe liver and kidneys might be checked in the same way, were it possible to reach the nerves going to them, with- out violence. Notwithstanding the heart is kept in continual nuiotio by the presence of the blood, if its nerves were separa- ted, so that the communication were interrupted with the brain and spinal marrow, it would cease to pulsate, though its irritability, an original endowment of the muscle, might remain a considerable time. And still further, a wouiid or compression of the spinal marrow completely paralyzes the whole body,— which, if not speedily re- lieved, ends in death. For the sake of method, anatomists have made a regu- lar classification of the nerves: — From the brain, there are nine pair — a majority of which are the nerves of sense; — in other words, they are expended on the organs of sense, as the ear, eye, nose, and tongue. Issuing from between the bones of the neck, there are eight pair,— from between the joints of the spine, twelve ; — from the loins, five pair more ; — and the sacrum or last bone ofthe vertebral columj, five more, — making a total of thirty-nine sets of nerves, from the brain and spinal cord. ANATOMICAL CLASS BOOK. Fig. 67. 165 166 ANATOMICAL CLASS BOOK. Explanations of Fig. 67. A A. Cerebrum, or brain. B B. Cerebellum, or littla brain. C C. Crura Cerebri, or union ofthe fibres ofthe brain. D D. Crura Cerebelli, union of the two sides of the little brain. E E E. Spinal marrow. 1 1. Branches ofthe 5th of nerves, so often noticed in this work. 2 2. Branches of the sub-occipital nerves. 3 3. Branches of the four inferior cervical nerves, and the first dorsal, forming the axillary plexus, from whence all the nerves of the arm and fingers have their origin. 4 4 4 4. Branches of the dorsal nerves. 5 5. Lumbar nerves. 6 6. Sacral nerves. THIRTY PAIR OF SPINAL NERVES. These are first divided into ICigJit pair of Cervical, coming out between the bones ofthe neck, on either side, from the spinal marrow, — to be distributed to the muscles. Twelve pair of Dorsal, — in like manner, coming out between the dorsal vertebrae ofthe back. Five pair of Lumbar, — from between the lumbar or joints of the loins. Five pair of Sacral, — being a branch or termination of the spinal marrow in the os sacrum. Several cords, coming through the several openings, unite to form the great sciatic nerve of the leg. Another circumstance should not be lost sight of in this general survey of these organs — viz., the well estab- lished fact, that two threads may arise from the same root, and yet they sustain widely different offices in the econo- my : one may contribute to the contraction of a muscle, while the other carries the mandate for its relaxation. We are warranted in believing, that even in a minute nerve, which appears a single cord, that a number of dis- tinct parallel filaments are lying side by side, enveloped in the same" tissue, whose functions are widely different from each other. Of the nine pair of nerves from the brain, let us pursue ANATOMICAL CLASS BOOK. 167 them to their ultimate destination, not, however, with the vain expectation of ascertaining how it is that they exert an influence, but simply to contemplate the broad chart of sympathies which is thus spread for distributing and con- trolling that vitality which is so essential to order, to con- sciousness and to physical perfectibility. First — the olfactory nerves, taking their rise in the brain, having gone but little way within the skull, arrive at the top ofthe nose, where they suddenly divide into in- numerable hair drawn threads, which are lost in the lining membrane ofthe nose. The second, are the optic — expanding, when thej have penetrated the globe of the eye, through the back side, into a thin web — properly named the retina, which is the seat of vision. In this instance, arising from the same substance as the olfactory to all human appearance, is a nerve which can only be influenced by the presence of light. When the nervous system is agitated by disease, even in the darkest apartment, the participation which the optic nerve has with the diseased action of the whole, pro- duces the sensation of vision, and nothing else. If it can- not be the bearer of this one item of intelligence, it can do nothing at all. If another sensation is to be conducted to the mind, — even if it relates to a moat on the face of the eye, another set of nerves, entirely independent of the optic, must be the bearers. There is no property in com- mon ; no relationship allowing the one to perform the func- tions of the other; yet they both seem to possess the same general structure, the same component parts, and have an origin from the same fountain-head, and depend for their vitality upon the same circulation. The third nerve is generally distributed to the muscles ofthe eye, to give guidance to several of them. Further — the fourth nerve, arising from the brain, 168 ANATOMICAL CLASS BOOK. long, slender, and hair-like, is dispensed altogether upon one muscle, the one which rolls the eye downward towards the shoulder. The fifth nerve is the most intricate to understand. Lying almost in contact with the great artery ofthe brain, in the base of the skull, the single cord spreads itself out into the form of a reddish, fleshy pad, from which three distinct cords, all distinguished for their size have an origin. One of the three darts towards the eye, where it commingles with those we have been describing. The second branch, creeps through an orifice, and having reached the back part of the upper jaw, sends on a lash of fine lines, which find an entrance into the substance of the bones, and there furnishes the root of each tooth with one of them. Fig. 63. Explanations of Fig. G8. This plate will give some general idea of the intricacy of the nerves about (he face ; the most difficult part of the neurology of the head is concealed by the bones, though we have adverted to the in- dividual nerves, which have their origin in the brain. ANATOMICAL CLASS BOOK. 169 men uivm< B. (The C. ■ Insertion ofthe superior oblique muscle in the eye-ball. p. The inferior oblique muscle, taking its rise from a bone tJa ThG intseruLon ofthe tendon of the inferior oblique muscle in the first coat ofthe ball. ANATOMICAL CLASS BOOK. 209 COATS OF THE ETE. Such is the mechanical arrangement of the different coats or coverings of the eye, answering in use, to the brass tubes of a spy-glass, that one is fitted within the other, like a nest of boxes : they are three in number. Fig. 81. Explanation of Figure 81. This is a plan of the coats, or as they are sometimes termed, tunics. Reference should be made to this after reading the text. The natural figure of the eye, in outline, is pre- served. a. The Sclerotic, or first, hard tunic. y0 b. The Choroid, or fleecy tunic. c The Retina, or third and in- most tunic, which is an expansion of the optic nerve g — the certain seat of vision. d. The Cornea, or prominent, transparent circle, over which the lids close, in winking. e. The Crystaline lens, or little magnifying glass of the eye, about a quarter of an inch in diameter. /. Is the space filled by one of the fluids of the eye, and called the anterior chamber. g. The stump of the optic nerve, which is prolonged into the substance of the brain. 1st. The first is the Sclerotic* coat, thick, firm, and possessing but little sensibility. Its hardness gives secu- rity to the delicate membranes beyond ; affords attach- ment for the muscles; and by its elasticity, equally distends the ball, that none of the humors may suffer from pres- sure. Happily the hard coat is very rarely diseased. Fishes have a sclerotic coat strictly hard, being either cartilaginous or firm bone, graduated in this respect ac- cording to the depth to which they descend in search of food. Through this coat, in what is called the white * Sclerotic, from a Greek word meaning hard. 18* 210 ANATOMICAL CLASS BOOK. -of the eye, the occulist plunges a needle to cure some kinds of blindness. 2d. Choroid* is the name of the second coat, having a dark red color, and apparently slightly connected with the first. By carefully cutting off the sclerotic from a bullock's eye, with scissors, the choroid will be beautifully exhibited, sustaining the humors. Minute dissection, under a microscope, shows that this tunic is a complete web of arteries and veins ; — hence its reddish hue. Be- tween this and the sclerotic, fine silvery threads are seen, which hold a control over the Iris, yet to be described, — determining by their influence how much or how little light may safely be admitted into the eye. The inside of this membrane resembles closely woven wailed cloth, hav- ing a fleecy nap, similar to velvet, called Tapetum.i This tapetum is particularly interesting in a philosophical point of view, as on its shade of color, in a great measure, as will be more fully explained in the sequel, depends the power of seeing in the dark. 3d. Retina,^ so called from its resemblance to a net, completes the number, being the innermost and last. Its color is that of gum arabic, or ground glass: nothing can be more delicate, being too tender to bear its own weight. Infact, it is the expansion of the optic nerve, the imme- diate seat of vision. To see it well, an eye should be taken to pieces in a tumbler of water. "Choroides, — like a lamb-skin, fleecy. ♦ Tapetum — resembling cloth, called tapestry. tRetina, -— a net. ANATOMICAL CLASS BOOK 211 Fig. 89. Explanation of Figure 82. from dissection of a human eye, the organ being represented of the pro- per size. a. The optic nerve. b b. The Sclerotic coat cut and turned outward. c. A circular portion of the Scle- rotica, being a rim of the white of the eye, cut, and turned upward, having in its embrace the cornea. d. The cornea. ee. One half the Iris, in its place, the other half being removed. f. The Pupil, soon to be descri- bed, with the crystalline lens in its place. g. The Ciliary circle, or second vertical partition, within the eye, behind the iris. h h. Choroid coat. i. The Ciliary processes, or ruffle-like plaits ofthe ciliary circle, yet to be explained. A small portion of the iris is cut away to show them. ft. A portion ofthe iris cut and turned back. I. The floating points of the ciliary processes, also turned back. hi. The middle smooth part of the retina, seen by cutting a hole through the choroid coat. n. The roots ofthe ciliary processes, to which the black paint, secreted by the tapetum or inner surface of the choroides, adheres. o. The ciliary processes inserted into the sac which contains the crystaline lens. THE CORNEA. Anteriorly, that clear, shining wall, resembling a watch crystal, which furnishes the membraneous box, is called the cornea. Simple as this thin crystal appears, it is infinitely curious in structure. It is made of thin pellu- cid plates, one over another, held together by a spongy elastic substance. By maceration in water a few hours, the sponge will absorb it to such a degree, that the plates may be distinctly felt to slide upon each other, between the thumb and finger. Little glands, like bags of oil, only to be seen by the most powerful microscope, are lodged under the first plate, which are continually oozing out their contents / 212 ANATOMICAL CLASS BOOK. upon the surface, which gives the sparkling brilliancy to this part of the eye. As death approaches, this fluid forms a pellicle, like a dark cloud, over the lower portion ofthe cornea. This formation is taken to be a sure indi- cation of approaching dissolution. See fig. 81, letter d, and fig. 82, letters c and d, for representation ofthe cornea. iris. By looking into a person's eye, there seems to be a ver- tical partition, either black, blue, or hazle, as the case may be, which prevents us from looking into the regions beyond, — having a round hole in its centre. This is the iris, while its central orifice is denominated the pupil. How the diameter of this hole is enlarged or diminished, has never been explained satisfactorily. One fact, how- ever, is certain, that the pupil is large or small, according to the quantity of light that may be necessary to the for- mation of a distinct picture of the object seen, — and this change is effected without our being conscious of the action. From the reflection of such rays as are not admitted through the pupil, or central hole, we account for much of the lively brilliancy of the iris. On its back side it is rather fleecy. Over this is spread a black, blue, hazle, or tea-colored paint, which gives a permanent color to the eye. It has been remarked, that the eyes and hair ordi- narily correspond in color. Whenever the iris acts, as, for instance, it does in going from a dark into a light room, the pupil is made smaller, — acting uniformly in its fibres, to keep it circular. On returning to the dark apartment, the pupil enlarges again. A knowledge of this fact, will explain the reason of a painful sensation in the eye, caus- ed by a strong and sudden light. As soon as the iris has had time to diminish the size of its pupil, we can endure ANATOMICAL CLASS BOOK. 213 the same luminous object with perfect comfort. When we leave a well-lighted room, on first going into a dark street, everything appears lurid and indistinct. The iris soon begins to enlarge the pupil, to admit more light, and when that has been accomplished, although in compaia- tive darkness, we recognise objects without an effort. Acting independently of the will, its duties are like those of a faithful sentinel, always consulting the safety of the splendid optical instrument confided to its care, with re- ference to its subserviency to the being for whose use it was exclusively constructed. Were it otherwise,— were it left to our own care, how often it would be neglected, and indeed, totally ruined, solely for the want of undivided attention. Parrots have a voluntary control over the pupil, opening and closing it at pleasure. How this is done, or v\hy, in the constitution of that bird, it is necessary, we cannot determine. Cats, also, appear to have a similar power of graduating the quantity of light, admitted into their eyes, as it suits their own convenience. In carnivorous quadrupeds, the pupil is commonly oval and oblique, permitting them to look from the bottom to the top of a tree without much elevation of the head. Gramnivorous quadrupeds have an oblong pupil, placed horizontally, with respect to the natural position ofthe body. This form gives them the faculty of surveying the expanse of a field, at once. See fig. 82, letters e e, and k. Fig. 63, letters c c. CILIARY PROCESSES. Directly behind the iris, is a second curtain, having a central hole through it, corresponding with that through the first curtain, but nearly as large as the whole diameter of the lens. All the luminous rays which are converged by the convexity of the cornea, which is, in effect, a piano 214 ANATOMICAL CLASS BOOK. convex lense, cannot enter through the pupil; many of them strike the plane of the iris, and are reflected back, as on a looking-glass, without penetrating its substance. If any rays were to get through, by such an irregular pro- cess, it would produce great confusion, by destroying the outline and vividness of the image previously made on the retina, through the natural opening. To prevent such mishaps, the paint on the back ofthe iris is to absorb such rays as are not reflected, and have a tendency therefore to pass onward. Nature, as though fearful that circumstan- ces might so alter the condition of the pigment,* as that some light, notwithstanding this precaution, might pene- trate, has interposed this second veil, — solely it is sup- posed to stop all wandering rays. This ciliary curtain presents three thicknesses, and lastly, has a thick coat of black paint on its back. In or- der to give it treble security, as it regards thickness, it is plaited like the folds of a ruffle. There are seventy folds in the human eye, of equal width, nicely laid, one over the other. A part so highly important, cannot be over looked in studying the philosophy of vision. * Pigment, — paint. ANATOMICAL CLASS BOOR. 215 Explanation of Fig. S3. This plan presents a longitudinal section of the left eye and orbit. a. The upper eye-lid, shut. 6. The cornea. cc. The cut edges of the iris. d. The pupil or round hole through the centre of the iris, which, in the living eye, resembles a black, highly polished dot. ee. The cut edges of the sclerotic and choroid tunics, with the retina, before exhibited in the preceding drawings /. The crystaline lens, as it is lodged, with reference to other parts. gg. The Ciliary processes continued from the choroid coat. The plaits are here distinctly seen. h. The optic nerve running from the brain, through the bones, to the globe of the eye, apparently closely embraced by the straight muschjg. i. The levator muscle that raises the upper eye-lid. k. The upper straight muscle of the eye. I. Inferior straight muscle, its antagonist, on the under side of the ball, called depressor occuli. m. A section of the inferior oblique muscle, used in rolling the eye upward and inward, as in looking at a button laid above the root of the nose. The superior oblique, passing throvgh a loop, carries the eye downward and outward, as in looking at the top of the shoulder. These two muscles, by old writers, were termed rotato- res and amatores, in allusion to their office of rolling the ball in ex- pressing passions. nn. A section of the blood vessels and nerves, with a large quantity of fat, surrounding the optic nerve. 216 ANATOMICAL CLASS BOOK. HUMORS OF THE EYE. By humors, writers mean the fluids which distend the eye-ball. They are three in number, — possessing differ- ent densities, and varying much in quality, quantity and use. Besides fulfilling the first intention, — viz, disten- sion,— they are so purely transparent, as to offer no ob- struction to the free passage of light. Those only inter- ested in this description, as general scholars, by close ex- amination wiH*nave a perfect idea of them, and will con- sequently understand the real nature of some of the many causes that weaken the power of vision, or ultimately pro- duce a total blindness. The gratification afforded by the examination of a bullock's eye, — tracing the several parts by this paper, will be an ample compensation for the labor, because it will forever fix on the mind interesting facts, and lead the reader, insensibly, to a course of Reflections, productive of much intellectual enjoyment. AQUEOUS HUMOR.* The aqueous humor is the first in the order of demon- stration, lying directly back of the cornea,—so clear, that one unacquainted with the existence of it, would not suspect a fluid there. In volume, it is far less than the others : it keeps the cornea prominent, always at the same distance from the iris, in the early periods of life. {The space occupied by the aqueous humor, is called the ante- rior chamber of the eye. (See fig. 81, letter/".) Passing freely through the pupil, it also fills an exceedingly thin apartment, the circumference of the iris, called the pos- terior chamber.) Thus it will be comprehended that the iris, or in familiar language, first curtain, is actually sus- pended and floating in a liquor. * Aqueous---like water. ANATOMICAL CLASS BOOK. 217 Were it not for such a contrivance, the iris would soon become dry and shrivelled, by the intensity of the sun, and therefore rendered totally unfit to perform its appro- priate office of opening and closing the pupil. The aque- ous humor is never suffered to remain long at a time, but, on the contrary, is constantly poured in and again drawn off by an infinite number of invisible ducts. By being stationary, it would become speedily turbid, and finally lose its transparency. A knowledge of t^krapidity ofthe secretion has been the means of encouraging occulists to undertake novel methods of extracting cataracts, a kind of dark mote, through the cornea, as the most certain mode of restoring sight. Twenty-four hours after drawing off the aqueous humor, by a puncture, the anterior chamber will be full again. Old age, characterized by a gradual decay in the vigor of all the individual organs, shows also its insidious ap- proach in the eye. Vessels that have toiled with untiring diligence to the meridian of life, begin to show a loss of energy. Those which have carried the new, pure liquid, forward a less quantity in a given lime than for- merly,—■ while those whose task it was to convey away the old stock, are dilatory in the performance of their work. Hence, from being kept too long in the reservoir, in consequence of a tendency to become more turbid, it does not allow the light to pass with its former facility to the nerve ; elderly persons, therefore, have indistinct vision from this cause, similar to looking through a smoky at- mosphere. Fishes have no aqueous humor at all, as it could be of no service in the element in which they swim Kept, as the humor is, in its own capsule, it gives other advantages to the apparatus of vision : it is a concavo-con- vex glass, absolutely and indispensably requisite in an in- strument that will produce an image by the same laws that govern the eye. A sensible diminution in the quantity 19 218 ANATOMICAL CLASS BOOK. of this fluid, is very apparent in people advanced in years: the cornea becomes flatter; the segment of it is so altered, that rays of light are no longer converged as in younger days. This, together with corresponding de- rangements within the globe, constitutes the long-sighted- ness of old age, — mechanically overcome by wearing convex spectacles. So gradually are the changes wrought by age, that glasses of different focal distances are sought from time to Aie, to keep pace with the progress of decay. The ingenuity of man is nowhere more curiously dis- played, than in thus availing himself of his discovery of the laws of refraction, in producing artificial lenses to gratify his eye, a never failing source of enjoyment, long after nature has begun to draw the blind that will ulti- mately close between him and the world forever. CRYSTAL1NE LENS.* As magnifying glasses of different refractive powers give perfection to optical apparatus, so it is with respect to the lenses within the ball. By crystaline lens, is simply meant a body like a button, resembling pure flint glass, somewhat of the shape of a common sun glass, convex on both sides. Its posterior convexity is greater than its anterior, — thereby bringing the rays to a point a little dis- tance behind it. Careful investigation shows that this lens is made of a series of plates, applied to each other like the coats of an onion : the centre is firmer than the edges. As a whole, it possesses a highly refractive property, but in different degrees, according to the thickness of the lens, — receding from the centre to the circumference. Over the whole, to keep it from sliding in any direction, * Crystaline lens, — resembling crystal or glass. ANATOMICAL CLASS BOOK. 219 that the centre may not get without the axis of vision, is an envelope, having connexion with all the coats, where they are united on the borders of the cornea, and where it joins the white part of the eye. Being equally trans- parent with the lens itself, it cannot be conveniently ex- hibited. Cataracts, the most frequent cause of blindness, origi- nate in the lens; sometimes half way between the centre and margin, but ordinarily in the centre.1 They are either a peculiar deposition of opaque or milky matter, entirely preventing the ingress of light, or there is an opacity of some of the internal layers of plates, equally destructive to vision. Many children are born with this affection ; and at all ages, they are liable to form. To remove cataracts by extraction, the operator slides a sharp, thin knife, re- sembling a lancet, through the cornea, from one side to the other, cutting one half from its natural attachment — leaving it in the form of a flap, thus: Fig. 84. Explanation of Fig. 84. This plan represents an eve, surrounded by its natural appen- dages, with a knife passing through the anterior chamber. A dotted line indicates the lower edge of the flap, made by cutting offjust one half the cornea from its attachment with the sclerotica, in order to al- low the crystaline lens to escape, whenever the knife is withdrawn As a matter of course, the aqueous humor escapes in a twinkling, at the same moment, the capsule ofthe lens previously ruptured, designedly, by the point of the knife 220 ANATOMICAL CLASS BOOK. as it slides along, acts upon the lens by spontaneous con- traction, and protrudes it through the wound. Undoubt- edly the grasp which the straight muscles have on the ball, accelerates its escape Thus, in taking away the obstruction to sight, the whole lens is extracted. To couch, an operation often mentioned, and often per- formed, is to thrust a delicate needle through the white of the eye, just on its border, till the point reaches the lens, which is then depressed into the lower part of the eye, below the optic axis, so that light may, by entering the pupil, arrive at the nerve. In this last operation, fears are always entertained, that the lens may rise again to its former position, rendering a repetition of the operation indispensable. Secondary cataracts sometimes form, after couching or extraction, and arise in consequence of a thick- ening and opacity of the capsule, which is left behind. Such cases are more alarming in their progress than a disease ofthe lens, as no surgeon is warranted in promis- ing even a partial relief. If he attempted to tear away the membrane, he might also rend every other within the globe. A few facts of this kind which have a practical bearing, more or less interesting to every person, may lead to cor- rect views in relation to some of the diseases which are common to this curious organ. ANATOMICAL CLASS BOOK. 221 D Fig. 85. Explanation of Figure 85. This is a .scheme showing how a bad operator, by introducing the couching needle too near the cor- nea, may rupture the ciliary pro- _v cesses, and actually divide the ■"* lens in two pieces without moving it from the optic axis. A. The vitreous humor. B. The lens. CC Ciliary processes, torn by the lower part of the needle, thereby doing great violence and a permanent injury to the organ. DD. The iris. The anterior chamber of the aqueous humor. Explanation of Fig. 86. This figure represents the mode, and, in fact, the place into which the couching needle is intro- duced, in the operation of couching. A. The pupil is seen through the transparent cornea. B. The iris. C. The needle, with the handle elevated so as to depress the ^'The lens and point of the needle in outline; this precisely represents the position ofthe lens after couching. VITREOUS HUMOR. Beyond the two humors we have been describing, is the third, differing essentially from either of them. In volume it' far exceeds the others, — occupying more than two thirds of the whole interior of the ball. Its consist- ence is that of the white of an egg, but kept in place by its own capsule. When the sac is punctured with a pin, it flows out slowly in consequence of its adhesiveness. Like the preceding humors, it is transparent, allowing the free passage of light through its substance, and also pos- 19* 222 ANATOMICAL CLASS BOOK. sesses the additional quality of allowing the rays to sepa- rate again, as they leave the point at which they were converged just back of the lens. Observation proves that the vitreous humor is kept in place by being lodged in cells. Perhaps a piece of sponge might give a tolerable idea ofthe cellular structure, admitting it to be as trans- parent as the water which it absorbs. On its fore part it has a depression, in which the posterior convexity of the lens is lodged, — as represented in this diagram. Concave, therefore, in front, and convex behind, gives another kind of optical glass, known as the meniscus, — the crescent, faintly resembling the first quarter of the new moon. Fig. 87. Explanation of Figure 87. One dotted line indicates, in this diagram, the aqueous humor; an- other the iris, and a third the lens, and the fourth the vitreous humor. Let it be "remembered that all the space between the hack side ofthe lens and optic nerve, is filled com- pletely, with the glairy, vitreous humor, the third fluid, and inmost of the eye. OPTIC NERVE. Any person possessing an ordinary share of curiosity, can examine the optic nerve, at leisure, in slaughter houses, fish markets, and in fowls. In the human eye,— or rather extending from the globe to the brain, — the optic nerve is very much like a cotton cord, somewhat larger than a wheat straw, of a mealy whiteness, and not far from three quarters of an inch in length. Arising from the substance of the brain, it traverses the bony canal till it reaches the back of the eye-ball ; as soon as it arrives in contact, as it were, it is suddenly divided into innumer- able filaments, which wend their way into the globe, ANATOMICAL CLASS BOOK. 223 through very minute holes. From a fanciful resemblance to a sieve, this spot on the sclerotica, is called the cribriform plate. When the threads have emerged within, they as- sume another form, by expanding into a web, constituting the third or inmost box. Some believe the nerve is spread on a thin, unseen membrane, in the form of a highly or- ganized nervous paste. Here, on this pulp, having con- siderable range of surface, is the sole seat of vision. A vulgar opinion presupposes some exceedingly acute nervous point, — the exquisite place of vision. Nothing, however, is more absurd ; vision includes considerable surface. In the centre of the substance of the nerve, an artery pene- trates the eye, accompanying the filaments, to nourish the humors. When the cornea has been cut away, and the iris detached, this vessel may be distinguished, of a bright scarlet, spreading its hair-like branches about, like the limbs of a tree. The nerves which give sensation to the eye, connecting it with the system, may be noticed, as previously remarked, lying between the two first coats. The optic nerve conveys to the mind the sensation of the existence of things, as perceived by the eye, while the commands of the same mind are conveyed to the organ by these little threads of nerves, so insignificant, as to be often overlooked in a dissection made purposely for them. 224 ANATOMICAL CLASS BOOK. Fig. 88. Explanation of Fig. 88. In this figure, the cornea is cut away, and the sclerotic dissected back. This is a beautiful and easily accomplished dissection. In a bullock's eye all these delicate nerves can be readily displayed. A pair of sharp pointed scissors and a few pins, to hold parts to a board, are the proper instruments. In schools, ladies could display the whole of this beautiful optical apparatus. a. The optic nerve. b. The sclerotic coat turned back, so as to show the vessels of the choroid coat. cc. The ciliary nerves, seen piercing the sclerotic coat, and pass- ing forward to be distributed to the iris. The iris, so highly organized, is not supplied by any nervous influence from the optic, but by the hair-like nerves, here displayed, creeping to its margin between the two exterior coats. d. A small nerve passing from the same source to the same ter- mination, but giving off no visible branches. ee. Two vena vorticosa, or whirling veins, so denominated, be- cause they seem to fall into shapes, resembling falling jets of water; these return the *>lood from the eye, sent in by its central and other arteries. /. A point of the sclerotic, through which the trunk of one of the veins has passed. g. A lesser vein. h. The circular point of union, where all the coats of the eye, together with the cornea and iris, seem to be glued firmly together. i. The iris. ANATOMICAL CLASS BOOK. 225 k. The straight fibres ofthe iris. I. A circle of fibres or vessels, which divide the iris into the larger circle k — and the lesser one m. m. This letter points to the lesser circle of the iris. n. The fibres of the lesser circle. o. The pupil. PKiMENTUM NIGI1UM.* Lastly, to complete the internal structure, and fit it for the performance of its destined office, the inside surface ofthe second coat, choroides, is thoroughly painted black. In the order of explanation, this paint is just behind the retina. When the humors have been taken out, the pig- ment is readily examined. The use of it is very obvious ; viz., to absorb any aberrating or unnecessary rays of light, which would confuse the vision, or destroy the intensity of the impression on the expanded retina, or to suffocate them entirely. SKIN OF THE EYE, OR TUNICA CONJUNCTIVA. Behind, the eye, by its long cord of optic nerve, seems to rest on one extremity of an axle : — in front, the skin, passing over the eye, as it comes down from the forehead, to join the cheek, is the other. To comprehend, clearly, the manner in which the eye is fastened, before, — observe how the skin turns over the edge of the lid, going about three quarters of an inch back, striking the ball to which it is made fast, then folded back upon itself, adhering to the whole anterior surface of the cornea, — dipping down and finally mounting over the margin of the lower lid, and ultimately loosing itself on the face. As we cannot recognise this on a living eye it will at once lead one to suppose it is as clear as glass which is the case. Streaks of blood, when the eye is in- * Pigmentum Nigrum — black paint. 226 ANATOMICAL CLASS BOOK. flamed, lie covered over by the tunica conjunctiva. Now if particles of sand, or other irritating substances get under either eye-lid, they cannot possibly enter but little way, before reaching the duplication of ihis transparent skin; there is no danger, therefore ; the offending matter cannol get so far between the socket and ball, backward, as to abridge the free motion of the organ, or do a permanent injury to the parts. This partition, or doubling over of the conjunctiva, is a curious provision, as we are thereby enabled to reach the source of irritation. The principle of introducing- eye-stones, to extract foreign matter, is this, and not owing as vulgarly sup- posed, to the crawling about of a smooth piece of sulphate of lime, on some forty or fifty feet. The stone is so much larger than the extraneous body, already there, that it ex- cites a proportionably larger quantity of tears, to wash it away : in effect, therefore, we submit to a greater tempo- rary evil, to get rid of a lesser one. Serpents annually shed their skins, which, unaccount- able as it at first appears, are whole over the eyes. That thin sheet, so very clear and fine in texture, is the con- junctiva, showing its origin, — hence a similar origin may safely be inferred over other eyes. Every species of animal with which naturalists are conversant, possess this defensive transparent membrane. THIRD EYE-LID, OR MEMBRANA NICTITANS. A third eye-lid is given such animals as are destitute of hands, or are incapacitated, by the arrangement of their limbs, from reaching their eyes. This is called mem- brana nictitans,—and a more striking piece of mechan- ism there is not in existence. It slides from one ano-le ofthe eye to the opposite one, under the first pair of lids, — and that, too, whether the others are open or shut, ANATOMICAL CLASS BOOK. 227 being totally independent of them in muscular action. Its use cannot be mistaken : it is on purpose for clearing away matter that may be irritating to the eye. Any ex- traneous substance is brushed from the cornea in an instant, by the broad sweep of the night lid. Birds that seek their food in the night, as owls, defend their irrita- ble organs, through the glare of daylight, by drawing over this singular curtain. Dogs, cats, foxes, wolves, bears, lions, tigers, &c, can each of them, by this brush, re- move the minutest mote from the cornea, more expedi- tiously than any occulist on the globe. TEARS. Perfection is everywhere observed in animal mechan- ics. The eye would soon become a useless instrument notwithstanding the nice adjustment of its several parts, were it not for the external apparatus of eye-lids, glands and tears, whose combined action keeps it always in a condition to be useful. Were not the cornea frequently moistened, it would become dry and shrivelled. To ob- viate this, a sack of fluid is fixed just under the edge of the orbit, above the eye-ball, which is continually pouring out its contents by the pressure and rolling of the eye. Flowing through numberless apertures, it washes the crystal and finally passing into grooves, on the inner margin of both eye-lids, runs to their terminations in a small pin-like orifice, at the inner angle. To keep them open, a hoop is set in the mouth of this tear tube. This, too, can be shown by turning the lid outward by the finger. Finally, the tears are conveyed into the nose through a bony tube, answering the double purpose of keeping moist the lining membrane, on which the sense of smell depends. On both eye-lids, at the roots of the eye-lashes, are in each, a row of glands, equivalent to 228 ANATOMICAL CLASS BOOK. bags, smaller than pin heads, which ooze out an oily secretion, to prevent the adhesion of them together, as is sometimes the case when the eyes are much inflamed. Surely such manifest provision for contingencies, is another beautiful illustration of super-human contrivance. Explanation of Fig. 89. This plan exhibits the natural size of the passages ofthe tears. a Is the lachrymal gland, or organ that secretes the tears; showing its natural situation, with respect to the eye-lids. bb. The eyelids widely opened. if| c. The situation of the punc- ta lachrymalia,or the holes at the inner angles of the lids, through which the tears flow, to get into the tube which finally conveys the fluid to the nose. dd. The ducts continued from the puncta lachrymalia. ee. The angles which the ducts form after leaving the puncta. /. The termination of the lachrymal ducts in gg. gg. The lachrymal sac. h. The nasal duct, continued from the lachrymal sac. WHY DO AGED PERSONS REQUIRE CONVEX GLASSES! Age gradually relaxes the tension ofthe whole system; the eye, therefore, suffers in a corresponding ratio. The cornea becomes less prominent : —the convexity of the lens is also diminished, and the rays of light are conse- quently less convergent than formerly. The picture of the object is faint, because the rays have a tendency, by their divergency, to impinge at a supposable plane, be- yond the retina. ANATOMICAL CLASS BOOK. Fig. 90. Explanation of Fig. 90. In this figure is represented the effect of old age on the humors; without the intervention of the glass A, the rays have a direction which would form the image at some distance beyond the retina, as at B. But, by the convex glass A, which, for example, is the spec- tacle worn by aged people, the direction of the rays of light is so corrected, that the image falls accurately on the bottom of the eye, or retina. When the convex lens is interposed between the eye and object, as represented in the above diagram, the rays are made more converging, — so that the picture strikes exactly and distinctly on the nerve. People slide their spectacles on the nose unconsciously till the true focus is procured. WHY DO NEAR-SIGHTED PERSONS SEE INDISTINCTLY 1 Either the crystaline lens, but more generally the cor- nea, is too prominent — converging the light too sudden- ly ; —that is, converging the luminous rays at an unnatural place within the vitreous humor. An indistinct outline of the object is the effect of their great divergency, after decussating—before they arrive at the retina. The fol- lowing diagrams will illustrate the subject far better than a whole volume of written explanations. Fig. 91. 20 230 ANATOMICAL CLASS BOOK. Explanations of-Fig. 91. In this figure, the convexity of the cornea, or the focal powers ofthe lens, being too great for the length ofthe axis ofthe eye, the image is formed at A, before the rays reach the surface of the retina, or inner box, illustrated in Fig. 81, letter c; and after coming accu- rately to the point, they again begin to diverge ; which diverging rays, striking the surface of the retina, give the indistinct vision of the near-sighted individual. But as this indistinctness of vision proceeds from no opacity, but only the disproportion of the convexity ofthe eye to the diameter, the defect is corrected by a concave glass, represented in the next figure. Concave glasses are the restoratives ofthe near-sighted eye, by separating the rays, and carrying the image so far back as to place it on the retina. Old age, the de- struction of the first eye, eventually restores the near- sighted, by the gradual flattening of the cornea, till at threescore and ten such persons can see clearly and distinctly without artificial aid. Many near-sighted people totally ruin the organ by prematurely wearing glasses, as a focus is established which neither glasses can keep pace with in age, nor age thoroughly overcome. Explanations of Fig. 92. The effect of this glass being exactly the reverse of the convex, it causes the rays to fall upon the surface of the eye, so far diverg- ing from the perpendicular line, as to correct the too gieat converg. ence, caused by the convexity of the humors. When a near-sighted person has brought the object near enough to the eye to see it dis- tinctly, he sees more minutely and consequently more clearly, because he sees the object larger, and as a person with a common eye does, when as-isted with a magnifying glass. A near-sighted person sees distant objects indistinctly, and, as the eye, in conse- quence, rests with less accuracy upon surrounding objects, the piercing look of the eye is very much diminished; and it has, more- over, a dulness and heaviness of aspect. Again, the near-sighted person knits his eye-brows, and half closes the eye-lids; this he does unconsciously, to ch.mge the direction of the rays, and to cor- ANATOMICAL CLASS BOOK. 231 rect the inaccuracy of the image. Near-sighted people have but little expression ; the countenance loses all its dignity, by habitually wearing glasses. THE IMAGE OF AN OBJECT IN THE EYE, IS INVERTED. Rays of light going from the upper and lower points of an object, are refracted towards the perpendicular : that is, bent out of the course which they have a tendency to run, by the crystaline lens behind, where they unite in a point, — and, then crossing, diverge again. Here then, the image is bottom upward, as will be noticed in the preceding diagrams by the arrow, and its image on the retina. Decussation is indispensable to the vision of things. An object could not be represented on a point; there must be surface to create an image on, and by the laws of optics, the representation of the object, without an additional glass within the eye, must necessarily be as it is — bottom upward. THE OBJECT APPEARS IN ITS TRUE POSITION. Habit is supposed to be the cause of seeing objects as they really exist in relation to surrounding bodies. An attempt has been made to prove that the cornea is the true seat of vision, and that we see by means of erect and re- flected, and not by refracted and inverted images. A few philosophers conceive that the mind contemplates the ob- ject only, without reference to its representative on the retina, which is made there as a natural result. Certain it is, that without the image, there is no vision. How the brain is operated upon by the light that de- fines the object, will probably never be known. The minuteness ofthe picture traced on the retina, precisely like the object in every minute particular, is truly aston- ishing. By cutting off the coats of a bullock's eye and 232 ANATOMICAL CLASS BOOK. holding a clean white paper near, this beautiful exhibition can be leisurely observed. If a sheet of white cotton cloth, six feet square, is elevated 24,000 feet in the air, the eye being supposed one inch in diameter, the miniature of the cloth on the retina will be only one eight thousandth part of an inch square ;. which is equivalent to the 666th part of a line, — being only the 66th part of the width of a common hair! WITH BOTH EYES ONLY ONE OBJECT IS SEEN. At one side ofthe centre of each eye, there is a surface more susceptible of visual impressions than any other. These points correspond in both eyes—being precisely on the two retinas alike. An impression therefore on one, provided the light strikes them equally, produces precisely the same effect on both. This, instead of making vexa- tion, gives strength and greater vividness, as the images are on surfaces ofthe same structure,transmitting, through the two optic nerves, the same idea, or that indescribable something that creates an idea. The optic axes, by this explanation, will be understood. If one eye is distorted, — pressed by the finger one side, when we are in the act of contemplating an object, it will appear double, but less distinct in the one so distorted. The rationale is this ; viz. the visual surface on which the image is made, so exactly alike in both eyes, as to call up but one idea, being forced out of the optic axis, the rays still make the pic- ture, but on a surface, less highly organized, —that does not correspond with the surface on that retina which has not been disturbed. The two images have now different localities. No course of experiments are more within the reach of the scholar. ANATOMICAL CLASS BOOK. 233 Fig. 93. Explanation of Fig. 93. In this figure, B, B. the eyes> having their axes directed to A, will see the object C, double, some- where near the outline D, D. Be- cause the line -of the direction of the rays from C, do not strike the retina in the same relation to the axis A, B, in both eyes. If a can- dle is placed at the distance of ten feet, and I hold my finger at arm's length, between the eye and the caudle, when I look at the candle, my finger appears double, and when I look at the finger, the can- dle is double. Explanation of Fig. 94. A is exactly in the centre of the axes of both eyes ; consequently it is distinctly seen, and it also ap- pears single, because the fonn of it strikes upon the points of the retina, opposite to the pupils in both eyes. Those points have a correspond- ence, and the object is strengthened in the liveliness of the image. Again, the object B will be seen fainter, but single and correct. It will appear so because there is only one spot in each eye, which pos- sesses the degree of sensibility ne- cessary to perfect virion; thus, it will be understood, the object will appear single, as the rays of light proceeding from it have exactly the same relation to the retinas in both eyes. CROSS-EYED PERSONS SEE ONLY WITH ONE EYE. With such as have a permanent squint, (cross-eye,) only one eye is attended to, though they may not be apprehen- sive of the fact. From continued neglect, the distorted orsan wanders farther and farther from the axis of vision, * 20* 234 ANATOMICAL CLASS BOOK. till it finally becomes totally useless: hence one is doubt- ful, at times, which way the cross-eyed person is looking, from a want of parallelism in the motions of the eyes. When the wandering eye is exclusively attended to, the vision appears unimpaired. The image is well painted in the natural one, but weak in the other, solely because the place of the image does not correspond with the place of the image in the first. The mind, instinctively, therefore, is devoted to the eye that gives the liveliest impression, to the entire neglect of its aberrating fellow. THE PUPILS OF AN ALBINo's EYES ARE RED. If a person is born without the pigmentum nigrum,— which is the paint to suffocate all unnecessary light, after the image is formed, — the blood vessels of which the tunica choroides or second coat is made, are not hidden; consequently, they show through the transparent humors, like a sparkling red gem, the size of the diameter of the pupil. Such persons can see better in a weak light than in broad day, because the brightness of the sun's light dazzles, and produces a tremulous motion in the whole or- gan. As an evidence that this redness is caused by the blood in the vessels, after death, when it coagulates, the redness in a great measure disappears. White rabbits, white mice, besides a vast variety of birds, have no pig- ment on the choroides, and are therefore distinguished for red pupils. The existence of the pigmentum nigrum, is an evidence of a day-seeing eye. In man the want of it, constituting the albino, is an anomaly. A morbid action of the absorbents sometimes removes the paint, and the pupil, to the surprise of observers, be- comes scarlet. A partial absorption of it is often the cause of a diminution of the original powers of vision. under such circumstances, the pupil assumes a bronze ANATOMICAL CLASS BOOK. 235 hue, accompanied by a debility and tremor of the globe under the influence of a moderate degree of light. MANY ANIMALS SEE IN THE DARK. Owls, fishes, cats, bats, &,c, instead of the pigmentum nigrum, have a silvery paint of a metallic lustre, where others have the black paint, which operates like a concave mirror, in reflecting the light from point to point, within the eye, illuminating it, till its concentration excites the retina to perceive. When viewing a cat's eyes in the re- mote part of a dark room, there are certain positions, in which they are seen by the observer, by the reflected light within themselves, as though they were phosphorescent: their brilliancy is very peculiar. Upon the principle of a looking-glass behind the retina, all the night prowling an- imals are qualified for seeing with those few rays of light, which the constitution of their eyes is formed for collect- ing in the dark. By daylight, they perceive objects, as man does in the dark, indistinctly. Nature is remarkably economical in the use of matter which enters into the composition of animal bodies. If a man be kept a long time in a perfectly dark room, the black pigment is taken away; but a compensation is giv- en him, for he can then see as perfectly in the dark, as he could before in the light. On the other hand, the paint is deposited again when he is restored to the light of day. This point has been decided in the persons of state pris- oners kept in the dungeons of European despots. FISHES CANNOT SEE IN AIR AS WELL AS IN WATER. When the rays of light pass from a rarer to a denser medium, as from air into the aqueous humor of the eye, they are refracted towards the perpendicular. Now the fish has but a drop as it were, of aqueous humor, and, 236 ANATOMICAL CLASS BOOK. moreover, the light arrives at its eyes through the whole body of water above. The light is refracted only in a small degree in entering its eye, because the humor is of the same density of the fluid through which the light is transmitted. The cornea is quite flat; if it were promi- nent, like the human eye, the sphere of vision would be too circumscribed; — but by giving a prominence to the whole, and placing the crystaline lens in the fore part of the eye, they have a long diameter,—and with the provision of a large pupil, are completely fitted for seeing in the element in which they were destined to live. With an eye of this description they must necessarily see in air, as other animals see in water. Those animals whose eyes are organized for seeing in water, see but indifferently in air. Hence, in those cases where the habits of the animal require it to see in both elements it is provided with two sets of eyes, or with eyes accommodated for seeing in both. It cannot be denied, that, in general, land animals can see under water, and aquatic animals in air; even man sees under water, although the contrary has been main- tained. It is not, however, possible that the same eye is ever so organized as to see equally well in both elements. Land animals always see indifferently in water, and aquatic animals imperfectly in air. The one is long- sighted in water, and the other short-sighted in air. An animal in which the eye is adapted for seeing equally well in air and water, can have but imperfect vision in either. These conclusions are in conformity with what is known of the power of vision in those animals which live partly on the land and partly in the water. The seal lives in both elements; but it has but imperfect vision in the air. We have the most satisfactory evidence of the short- sightedness of seals, from a series of experiments and ob- servations, made in Boston harbor. ANATOMICAL CLASS BOOK. 237 As a light looses more of its power in passing through water, than in passing through air, and is still more weak- ened in its progress through the membranes, it follows, that owing to this cause, vision must be less distinct un- der water than in the air. MAN CANNOT SEE DISTINCTLY UNDER WATER. A man under water, sees objects as a very aged per- son sees through a concave glass, placed close to the eye. The fish is long-sighted under water, and man is short- sighted. If he uses spectacles, whose convexity is just equal on both sides to the cornea of his own eye, he will see under water distinctly. The necessity of this is ob- vious ; the aqueous humor is of the same density with the water, and there cannot, therefore, be any refraction of the rays in passing from the water into the land-seeing eye. Euclid supposed that vision was occasioned by the emission of rays from the eye to the object. He thought it more natural to suppose that an animate substance gave an emanation, than that an inanimate one did. In 1560, the opinion that the rays entered the eye, was established. Kepler, in 1600, showed, geometrically, how the rays were refracted through all the humors, so as to form a dis- stinct picture on the retina; and he also demonstrated the effect of glasses on the eyes. HOW DOES THE EYE ADAPT ITSELF TO THE DISTANCE OF OBJECTS. No one has satisfactorily answered this question. One philosopher supposes the eye at rest, when we examine a distant object, as a mountain, the spire of a church, or a landscape, but, that in the act of seeing near objects, there is an effort. It has been supposed that this effort 238 ANATOMICAL CLASS BOOK. is the action of the straight muscles, exhibited in the first plan of the cordage of the eye, compressing the globe, so equally, as to elongate the eye, and lengthen the axis, so much, as to favor the union of the pencils of rays on the retina. This could not take place in many aquatic ani- mals, in whose eyes the sclerotica is perfect bone. Another opinion is, that the eye is at rest in looking at near objects, and laboring, when viewing things at a dis- tance. Another is of the opinion that the iris contracts, and so draws the circular margin of the cornea towards the pupil, as to make it more or less convex, according to circumstances. A great variety of experiments have been instituted, to determine, accurately, whether there really is any change made in the length of the axis of the eye-ball or not, but none of them can be certainly relied upon. A favorite theory has had its advocates, that the crystaline lens has an inherent power of altering its de- gree of convexity ; and thus accommodates the eye to all distances. The truth is, an action takes place in the eye, in adapting itself to near and distant objects, which de- pends on that vital property of a living system, which no theory can reach, and which the deductions of human philosophy can never with certainty explain. ANATOMICAL CLASS BOOK. 239 QUESTIONS. How many coats has the eye ? What is the cornea ? How many humors has the eye ? What is the office of the lens ? What is the retina ? What do you understand by the pupil ? Where is the iris located ? What is the use of the ciliary process ? Where is the pigment found ? Why is the pupil red in the albino ? What is the function of the iris ? Why is but one object seen with both eyes ? What is the cause of squinting ? How are some animals able to see in the dark ? Why cannot a man see tinder water ? Why are convex spectacles necessary for the aged What causes near-sightedness ? On what does the color of the eye depend? What is the position of the image on the retina ? How does the eye alter its focus ? What is the use of the aqueous humor ? On what does the brilliancy of the organ depend ? Where are the tears secreted ? What is the effect of distorting one eye ? How many muscles are attached to the globe ? 240 ANATOMICAL CLASS BOOK. FEELING, OR TOUCH. Touch is a sensation excited by the contact of bod- ies, by which we are enabled to appreciate their various qualities, as hard, soft, — heat, cold, wet and dry. The immediate seat of this sense, is at the point where the nerves terminate in little papillae, and therefore most per- fect at the points ofthe fingers. This sense is undergoing incessant changes, from infancy to age. That general sense of feeling over all the surface of the body, by which we can designate the forms and other characters of substances brought in contact with the skin, we define to be perception. SMELLING. Perhaps the sense of smelling is of the least conse- quence to man, of all his senses : nature designed it and placed it as a safeguard over the stomach, — to detect the hurtful from the wholesome food, — and in savages it an- swers this purpose, being always in requisition. In civil- ized life, however, it is of very little consequence. Its importance to brutes is manifested continually. ANATOMICAL CLASS BOOK. 241 TASTING. This sense resides in the tongue,on which the gustatory nerve terminates, in the form of very small tubercles, be- ginning at the point and reaching quite into the throat. By it we distinguish certain qualities, as sioee.t, sour, bitter, acrid, &c. Before the sensation is complete, the sub- stance is necessarily dissolved in the saliva of the mouth, by which means it is uniformly presented to the nervous papillae. «w L 242 ANATOMICAL CLASS BOOK. THE GLANDS, OR ADENOLOGY. Glanos are generally round, fatty bodies, placed at short distances both internally and externally, — whose function is either to secrete a fluid, or change the quality of that which has been collected by another gland in the neigh- borhood. Thus, the salivary glands about the inside of the cheek, and below the tongue, secrete the saliva of the mouth. The lachrymal glands secrete the tears, and the mucus glands secrete mucus. Their importance in the animal economy is very great. Tumefactions, or sudden swellings of glands by severe colds, indicate, by the de- rangement they cause to other organs, their high con- sequence. INTERNAL ORGANS, OR SPLANCHNOLOGY. Under this division, is embraced the viscera or con- tents of the three great cavities, viz, in the head, chest and abdomen. Of the contents of the skull, we have al- ready treated. VISCERA OF THE THORAX. Within the thorax or chest which is bounded by the ANATOMICAL CLASS BOOK, 243 neck above and the diaphragm or midrif below, are con- tained the following organs, viz ; the pleura, lungs, heart, thymus gland, oesophagus, thoracic duct, arch of the aorta, branches ofthe cava, vena azygos, eight pair of nerves and part of the sympathetic nerve. PLEURA. Two membranous sacks are lodged in the chest, one on either side, attached closely to the ribs, but their sides meeting in the middle, under the breast bone, unite and form a partition, called mediastinum. Thus the chest is lined, so that each lung has an independent apartment. The heart, enclosed in its case, lies in a triangular space between the two lungs. DIAPHRAGM. This is nearly a horizontal partition between the chest and abdomen, and is perfectly muscular. Its border ad- heres to the ribs, breast bone and spine. Through it, near the spine, are openings for the passage of the swal- low, blood-vessels and nerves. The diaphragm is a muscle of respiratiom, — rising up- ward, as the lungs collapse, and falling down again, as the lungs become inflated. LUNGS. There are two membranous organs, by which breath ing is effected. The physiology of the function of the lungs has been considered, in detail with the circulation ofthe blood. They are divided into right and left: the right lung has three lobes, but the left, only two. They seem to be made up of a spongy substance, air tubes and blood-vessels. Their use cannot be misapprehended. 244 ANATOMICAL CLASS BOOK. By respiration is meant the ingress of air into the lungs, and by expiration its egress from them. Voluntary respiration depends upon the will, when we are awake, but spontaneous, is the respiration of sleep. It is thought that the exciting cause of the process, is the irritation of the nerves in the air cells, which by a consent of parts, gains the assistance of the diaphragm and inter- costal muscles and ribs, to expel it. The object of respi- ration, is the oxygenation ofthe blood. Though the vital temperature of the body cannot be readily accounted for, it is generally admitted that heat is developed by the action of the atmospheric air on the volume of blood exposed to its influence with the air cells. As an introduction to a description of the vocal apparatus of man, and other animals, it seems necessary, first, to explain both the process of breathing, and its necessity, in the animal economy : because, in the sequel it will be apparent, that without lungs, there could be no voice. Such is the constitution of every living creature, that a free use of atmospheric air is absolutely necessary for sus- taining life. The mere circumstance of being surrounded by air is not sufficient; if it were, there would be various ingenious devices for maintaining life, after the lungs were rendered useless by disease or accident. It is absolutely necessary that air should be taken into the system, and brought in contact with the moving blood. The various modes by which nature has accomplished this, in the mechanism of some animals, will now be con- sidered. If Spallanzani and some others are to be credited, in their accounts of what they discovered by the microscope, we have the first plan of a breathing structure. Spallan- zani, pretended he saw the respiration of animalcules in vinegar. They were shaped like stars, and in the centre of each were two dark globular spots, one of which he con- ceived to be the heart pulsating, and the other the lungs. ANATOMICAL CLASS BOOK. 245 Every two or three seconds, to use his own words, they were slowly blown up, three or four times their natural size, and then slowly compressed again. A modern phy- siologist remarks, that the Abbe must have forgotten him- self in assigning them lungs, for they were evidently aquatic animals, and therefore did not require them. Passing by the microscope let us examine something more tangible, —the families of insects. They are so organised that in proportion to their bulk, they require a prodigious supply of air. The heart is the only percepti- ble organ in flies and worms: how their breathing organs are constructed, we are totally ignorant. But pertaining to that apparatus, the existence of which cannot be questioned, are an immense number of air tubes, coursing over and through every part of them, distinguish- able with the naked eye, resembling white lines. It is necessary that these be always distended. They open, generally, with free mouths, on the sides ofthe body, and wherever there is a ring or line, it marks the place of one of them. In worms, it also appears necessary that the air holes or spirucula, be perfectly free and open. The moment a little varnish is applied, ever so delicately, to the last holes, that portion towards the tail is paralyzed. By closing the next two another ring is palsied ; if all but the two last, to- wards the head are closed, it still lives, though it cannot move : but when the last of the series are closed, it dies immediately. Some vermin require more air, judging from analogy, than others much superior in size. So variously are the tubes ramified, that the viscera appears to occupy only about one fifth ofthe whole internal cavity. Before insects arrive to their perfect state of existence, they are destined to undergo several interesting changes. First they are worms, ordinarily of a loathsome and dis- 21* 246 ANATOMICAL CLASS BOOK. gusting appearance ; and lastly, a beautiful winged insect, the object of peculiar admiration. In this change, there is nothing discoverable to the philosopher like the death and resurrection of the insect, so often the theme of writers. It does not die, while undergoing the change, if it did, the process would never be perfected : close the spiracula and there is forever an end to its existence. While the caterpillar crawls on its numerous feet, un- der its coarse, hairy skin, it has six legs, inimitably folded next the body ; — two pair of wings, that only require the sun's rays to astonish us with the beauty of their coloring; and a proboscis, nicely packed away, to sip the honey which will be its future food. The period finally arrives, when a development of these embryo organs is about to take place. Some inscrutable sensation, of which the worm appears to have an instinctive knowledge, as it seeks a quiet, safe and warm retreat, gives it a timely warning. The old covering becomes dry and dark ; the fluids cease to circulate in it, and gradually, as the legs and wings gain freedom within, they push it entirely off; — thus disentangled, it flits away on its untried wings, from flower to flower. While the skin was drying, the worm breathed as it did before, through the air holes of the old covering. Insects, it is supposed, never breathe by the mouth. The nymphae of gnats can raise themselves to the surface of a pool, and breathe by an orifice in their backs. The hydrocanthiri breathe by thrusting their tails out of water. Bugs, flies and worms which live in filth, ditches, and deep under ground, breathe the pure air which is in their air tubes, and when it is exhausted, they travel near enough to the surface to replenish their stock. But the maggot of the cruca labra has the most extraordinary ap- paratus imaginable. It shoots from its tail, a tube, resem- bling the slides of a spyglass, — one beyond another. ANATOMICAL CLASS BOOK. 247 The last has a star-like tuft on the end, which unfolding on the water, enables it, thus buoyed up, to breathe freely, while it floats about at pleasure, — in search of food. Fishes are without lungs, and yet they require a constant supply of air, though in a lesser quantity than animals with a double heart. Such is their peculiarity of structure, that they breathe a mixture of air and water together. The gills enable them to perform this process. Deprive water of its air, and the fish dies as soon as it would out of water. The free exposure of the gills to water is not sufficient : it is necessary to propel the water through them forcibly. If the feathery gills of a small perch could be unfolded and spread, it is not improbable that they would cover a square yard. This will not appear so extraordinary, when it is recollected that the nerve in a dog's nose, is spread into so thin a web, that it is computed to be four yards square. Observe the wonderful economy of nature; this web is so rolled up, like a scroll of parchment, that it could be packed away in a lady's thimble. Nearly one third of all the blood is exposed to the ac- tion of the air, in the gills, at the same time. The fish draws in a mouthful of water, and with a quick motion, by closing the jaws, drives it through the gills, and this im- parts vitality, and restores the red color to the dark blood ofthe veins. Various tribes of fishes which seek their food in the mud, and foetid, turbid water, have a striking provision for defending their gills; otherwise they would become clog- ged, and breathing would be interrupted by the very filth in which they were actually created to live. Their gills are small, and covered by the common skin ofthe body. The water is taken at the mouth, and driven with the same force, as in the other case, but emptied through holes on each side of the neck, just back of the jaws. The force is always sufficient, by dividing the water into 248 ANATOMICAL CLASS BOOK. distinct portions, to keep the openings completely clear. In fact, the action is like that of an apothecary's syringe. A familiar example of this sort of animal mechanism may be seen in the lamprey eel. A similar breathing apparatus is provided for shell fishes, having, however, an additional contrivance, by which they can live a considerable time out of water. Here let the mechanism be particularly noticed, and admired too, as the first step towards a terrestrial animal. As those in- habiting salt water are necessarily exposed, by the reced- ing of tides, without a limb to assisl them in regaining their home, and so organized with extensive gills, encir- cling two thirds the circumference of the shell, that they cannot breathe air, their apparently helpless condition has been provided for in this interesting manner ; viz. they are furnished with a long elastic pipe, which is a reservoir for water. At necessary intervals, the fish ejects a drop with surprising force, through the fringes ofthe gills, and then remains quiet, till some instinctive sensation warns it ofthe necessity of again working its forcing pump. Being cold blooded, that is, having the single heart, one throw ofthe brake suffices for a long time. In travelling over a clam bed, at low tide, the tremor communicated to the fish, apprises it of approaching dan- ger, — and the nearer the observer advances, the more distinctly can he witness the amazing projectile force with which the clam drives a little column of water up through the sand. This is only part of the contents of the tube. Nothing but continued irritation will induce the clam to part with the remainder, — which is noticed, in digging, just as the shell is exposed to the light. By this reserved fund, it can live many days, in open air. It is by this tube of water, that the oyster is kept alive in the shops. As the exposure in the open air, ANATOMICAL CLASS BOOK. 249 weakens its system, it recruits itself, by jetting a drop of water through its gills. This drop may be seen morning after morning, on a dry board : — but when the reservoir is wholly exhausted, it opens its shell, fearless of conse- quences, and seeks in despair, wherever it can reach, a fountain, to replenish its engine : —thus it languishes, and at last dies, a protracted death, in search of its ac- customed element. ** No class of animals ane-more wonderful on the other hand, than the amphibious. They live alternately in two elements, — hearing and seeing tolerably well in both. The structure of some of their organs of sense,-l»»i t already been considered. But it is not true, as too gene- rally believed, that they alternately respire air and water, or a mixture of both. They are cold blooded animals, it is true, with a single heart — as, for example, the frog and aquatic lizards. The water seems to be their peculiar element, but after all, they breathe the air exclusively. They constitutionally require only a small quantity of oxygen, or vital air, to sustain life, and keep the machinery in operation. They have lungs, but they have but a faint re- semblance to those having warm blood, with a double heart. Their lungs are merely membranous bags or cylinders, which in their dry, prepared state, appear like bubbles of froth. The next extraordinary circumstance is this — that breathing is an act depending on the will; that is, they can breathe regularly, at short intervals, for days together, or they can stop the respiratory process for hours, or perhaps days, and continue equally vigorous. Fishes, we have seen, force the water through their gills : the same process of forcing air into these membra- nous tubes, is accomplished in amphibious animals, by a very little additional mechanism —the mouth acts precisely like a bellows. The jaws are grooved above and below, that they may be air tight, and a slit, acting like a valve, is placed at the root of the tongue, over the wind-pipe JL* 250 ANATOMICAL CLASS BOOK. leading to the lungs. Let it be recollected that the mouth is never opened, except for food : the air is drawn in through very small nostrils, which in the frog and neut, are not larger than cambric needles. The animal slowly draws its mouth full of air, and when sufficiently distend- ed, forces it through the valve, by the skin, which looks like a pouch under the lower jaw. The lungs being full, give additional size to the body. The abdominal muscles re-aetr and slowly press it out again, and thus we have an example of the mode by which this class of animals breathe. If the frog's mouth be kept open with a prop, it will inevitably die, as there is no power by which it can inhale air, short of the bellows of its jaws. It requires no phi- losophy, after becoming acquainted with these interesting facts, to account for their large mouths and broad jaws. No other shape or structure would so completely consti- tute the bellows. Neuts, lizards and the camelion's lungs, are cylinders, running down the sides of their bodies, the whole length, and as they force in the air precisely by the same process, it will explain the reason of their appearing fat at one time, or thin and lank at another. When irritated, or in fear, they blow up their bodies to frightful dimensions, to appear more formidable, upon the same instinctive princi- ple that cats, dogs, hedgehogs and fowls, bristle up their covering at the approach of an enemy, superior to them in strength. The different colors with which the camelion so readily dresses itself, depend on this peculiarity of its lungs. The skin is covered with an exquisitely fine covering, like vel- vet. If the lungs be filled to a certain extent the swelling of the body erects the fleece, so that the manner in which the light strikes it, makes the animal appear green, white, or of other colors: another blast into the lungs, gives ANATOMICAL CLASS BOOK. 251 another inclination to the fleece, and it has another tint. - When, by irritation, its body is blown up to its greatest dimensions, various modifications of these colors are exhibited. From this tribe of reptiles, the first advance is made towards endowing animals with the power of producing vocal sounds. The water is only capable of propagating a vibration, but that with great certainty and strength, and nature has constructed an ear, suited to the element and the habits of all aquatic beings. To have bestowed an ear susceptible of receiving the modification of sound, would have been superfluous, inasmuch as the modifica- tions are alone effected in the vocal box of those breath- ing air. The atmosphere is the medium of modified sound : it is an elastic medium which can be put in motion by the vibration of solid bodies. It is a medium, which, when set in motion by a mechanical coutrivance of the greatest apparent simplicity, transmits the wants of animals, in what is denominated its natural cry, and in man, expresses not only his wants, his pleasures, and his pains, but all his thoughts, — because his voice represents ideas. Lan- guage, therefore, is the symbol of thought. The voice of all animals remains the same through endless generations, unless the vocal apparatus is artificial- ly altered. Indeed the vocal organs are so constituted, that they admit of little variety in their movements : — every succeeding class, however, exhibits an additional muscle, a bone, or some difference in the shape of the tongue,' giving it the power of either making one more sound than the race below, or some modulation of the original tone. Were it not for this progression in the con- trivance, the voice of all animals would be precisely the same, like sounding one note continually on a musical instrument. 252 ANATOMICAL CLASS BOOK. Let us examine another curious mode of respiration, peculiar to birds. Although there is an external resem- blance, in the shape of their bones, to quadrupeds, and the muscles >hich move them are similarly arranged, to effect a circle of motions, their structure has reference to their wafting themselves through the air. In the first place, the long bones are without marrow — being hollow tubes, filled with air, these actually have openings communicating with the lungs. At their further extremities they permit the air to circulate into the ends of each feather ; — and lastly, the body has large apart- ments exclusively appropriated for the reception of the same air. Their lungs, unlike the light frothy tube of reptiles, is spongy and gorged with blood, and totally un- like those belonging to any other animal. In the bird, the lungs are open at each end, and are so closely tied down to the back bone and ribs, that they admit of little or no distention or contraction. Their breathing is effected in the following manner; viz, the air is drawn into the vacuum caused by the pressure of the strong muscles of the abdomen. In other words, the weight of the atmosphere forces it in, so that the current rushes through the whole length of the lungs, where the blood is waiting for its appearance, and passes to the extremities of all the bones and feathers. The proper change being wrought in the venous blood, it is circulated again to the heart, while the muscles again empty the lungs and air cells, contiguous, by a general compression of the whole. Here is discoverable the me- chanism for producing voice, seen in its elements in the frog, improved upon, by additional cords and vibrating cartilages, susceptible of receiving a current of air, in a manner a little different, to produce one, two or three different tones. Lastly, nature has effected respiration by a more com- ANATOMICAL CLASS BOOK. 253 plex piece of mechanism, in those animals whose bodies are divided into two apartments by the diaphragm. A difference of structure does not appear in the air cells of the lungs of about forty varieties of animals, including man. The only circumstances observable relates to their shape and subdivisions, depending on the configuration of the cavity in which they are lodged. The human lungs are suspended in the chest, much as they are in brutes, by the wind-pipe, and so tied down at the upper part of the neck, and so carefully fitted to the dimensions of the box, in which they are lodged, that no position ofthe body can'throw them out of place. There is a right and a left lung, perfectly independent of each other, and separated by a middle partition. Exactly in the centre of this partition, in quadrupeds, the heart lies, but in man, it is on the left side, and there- fore projects into the cavity of the left lung. They are made up of millions of air cells, which are filled at every inspiration. The blood, directly from the heart, is thrown into them in prodigious quantities, and circulates so mi- nutely, that each air cell is completely surrounded by a sheet of dark blood. VOICE. We shall now inspect the contrivance by which sounds are produced by animals. By voice animals have the power of making themselves understood to their own species—and these sounds are either articulate or inarticulate. Language is an acquired power, having its origin in the wants of more than one individual. Man, without socie- ty, would only utter a natural cry, which sound would express nothing but pain. Supposing a human being to have been entirely forsaken oo 254 ANATOMICAL CLASS BOOK. by those of his species, in that stage of infancy, when he could have no recollection of anything pertaining to his race, his voice would, in essence, remain the cry of an infant, only strengthened in tone, at a particular age, by the development of the vocal organs, lo their destined size. But let two individuals be placed together, but without communication or knowledge of the existence of beings similar to themselves, the natural cry of each would un- dergo modifications : the one would make a sound, to express a particular sensation, which in time would be un- derstood by the other : a repetition of the same note would be the sign of that sensation in future. An additional sensation, having an intimate connexion with the first, would require a variation of tone, — and this would also become a symbol of two sensations. Here then would be the origin of language. Multiply the spe- cies, and each new member of the society would express some other sensation or want, by another modification of the original cry. Here we discover the certain commence- ment of a spoken language ; these different sounds becom- ing classified, constitute a dictionary, in which each word is the mark or sign of particular sounds; —thus, if an in- dividual can imitate the sound, or a series of sounds, he masters a language. Let it be remembered that man could never arrive to this perfection in sound or language, if his vocal organs were not differently constructed from brutes. Such is the mechanism of theirs, that so many sounds, and no more, can be made ; but in man's organs. there is no limitation — no sound appreciable that he can- not imitate. THE VOCAL BOX OR LARYNX. Directly under the integuments on the front side ofthe ANATOMICAL CLASS BOOK. 255 neck, is a cartilaginous tube, the trachea or wind-pipe, built up of a series of narrow strips, which are portions of a ring ; therefore, it is always kept free and open. At its lower end it divides into two branches, going to the lungs on either side, but its upper portion is enlarged, just under the chin, and finally opens in common with the tube of the stomach and mouth. This enlarged part, quite promi- nent in man, is the larynx or vocal organ. Several cartilages assist in its formation, viz, the thyroid, cricoid, the arytenoid and the epiglottis. The cricoid is the foundation; the thyroid is the wall around it; the ary- tsenoid are appendages to the back ofthe cricoid, and the epiglottis is a valve, opening and closing the entrance into the wind-pipe, like the valve of a bellows. Fig 95. Fig. 96. Explanation of Figs 95. 96. The five cartilages are. 1. The epiglottis. 2. The thyroid cartilage. 3. the cricoid auxiliary Jand 4. The two arytenoid cartilages. 5. The two superior horns ofthe thyroid cartil- age. 6. The two inferior horns. 7. The suspensory liga- ment of the os hyoides. 8. The os hyoides. 9. The azygos ligament, connecting the os hyoides to the thyroid cartilage. 10. The two lateral liga- ments connecting the horns of the os hyoides to the superior horns if the thyroid cartilage. One of these diagrams presents a front and the other a back view of the larynx or vocal box. The bone of the tongue is seen, like half of a hoop marked 8, in both plans. 2 is the front of the thyroid cartilage, felt under the skin — protruding in the form of an irregu- lar tumor. The wind-pipe is the tube at the bottom of each larynx. 256 ANATOMICAL CLASS BOOK. The vocal cords — the membranes which vibrate to produce sound, as tbe current of air rushes by, are concealed, being placed inside. From the remarks in the text', together with tbe references, a very correct idea will be formed of the structure of this curious organ. By blowing through the wind-pipe of almost any animal, soon after it is slain, provided the larynx has not been injured, the vocal cords may be put in motion, and the sound which is produced will bear considerable analogy to the natural voice ofthe animal. Within the larynx, and consequently below the valve, are four delicate membranes, two on each side, put upon the stretch — being in fact, like shelves, — their thin edges nearly meeting from the opposite sides, so that there is scarcely any space between them. These are the vocal cords. When the air rushes out from the lungs through the wind-pipe, it must obviously pass through the larynx, — in doing which it strikes the tense edges of the cords, and produces a vibration. This vibratory motion given to the current of air, produces sound. In the cavities of the bones ofthe face, forehead and nose, its power is increased, and in the mouth it undergoes further modifications, and ultimately becomes articulate language. The teeth, tongue, lips, nose and fauces have each an influence in the production of articulate sounds. Hence grammarians have arranged the human voice under the appropriate divisions of guttural, nasal, dental and labial sounds,— expressive ofthe agency which each of these organs exert on the original tone, Shrillness or roughness of voice depends on the diameter ofthe larynx, — its elasticity, lubricity, and the force with which the expired air is propelled through the rima glot- tidis, or slit like chink, between the vocal cords. Because the larynx is smaller in women, and more elas- tic, their voice is of a different character. The breaking of the voice, vox rauca, noticeable in boys, at a particu- lar age, depends partly on the enlargement of the apart- ANATOMICAL CLASS BOOK. 257 ments within the bones, which generally take place at that important crisis of their lives, when the whole constitution undergoes a sudden change. But the mechanism of voice would have been incom- plete, were there not a number of exceedingly delicate muscles, which graduate the diameter of the narrow slit through which the sound escapes into the mouth. Uncon- sciously, they effect the requisite contractions, forever varying, according to the rapidity, intensity, or strength of the voice, in singing, conversation or declamation. Finally, the larynx is a musical wind instrument, of the reeded kind, on the principle of the hautboy. The near- ness of the vocal cords to each other resembles the reed precisely. All the tones of reeded instruments are effect- ed by finger holes, — but the tones of the human voice are varied by the extrinsic and intrinsic muscles, which shorten or elongate the vocal tube. Thus the same re- sult is produced by this process, — increasing or diminish- ing the diameter of the larynx, that is accomplished in the clarionet, bassoon, flute and hautboy, by a graduated scale of finger holes. Is not this another beautiful mechanical evidence ofthe existence of a Being superior to ourselves 1 22* 258 ANATOMICAL CLASS BOOK. THE VISCERA, OR SPLANCHNOLOGY. THE FOOD-PIPE, OR ^ESOPHAGUS. This is a fleshy tube, going from the back ofthe mouth to the stomach, through the chest, lying in the neck be- hind the wind-pipe. Its upper portion is called the pha- rynx, or fauces, and its lower, the cardiac extremity, termi- nating in the stomach. THYMUS GLAND. Infants and young children possess a singular gland, located just behind the top ofthe breast bone, which has the appellation of thymus gland. In adults, it is obliterated; hence it is supposed to be serviceable only in the early stages of our existence. THORACIC DUCT. Quite low in the abdomen is found a white, ex- quisitely delicate tube, which runs upward by the side ANATOMICAL CLASS BOOK. 259 of the spine, and finally terminates by communica- ting with a large vein in the angle between ihe neck and shoulder, on the left side. All the nutritious sub- stance which has been collected from the food in the in- testinal tube, — now called chyle, which is white like milk, is conducted to this thoracic duct, and thence car- ried on to be poured directly into the circulation, to be- come blood. ABDOMEN. Bounded by the diaphragm above, the pelvic bones be- low and the muscles at the sides, the abdomen is the most capacious of all the cavities. Its lining membrane is the peritoneum. Various organs, principally subservient to digestion, are contained within it. They are the following. OMENTUM. Vulgarly, the omentum is thecawl, —a sort of apron lying in front of the intestines, suspended mainly from the stomach. liver. Being the largest and heaviest viscus in the body, the liver has also a vast influence on the condition of the whole. It is divided into right and left lobes — the right is the largest, and occupies the right side, under the ribs. The left lobe lies partly over the stomach, in the other region. Its use is to secrete bile. 260 ANATOMICAL CLASS BOOK. Fig. 97. ANATOMICAL CLASS BOOK. 261 Explanation of Fig. 97. In this view of the abdomen, d, is the gall-bladder, lying on the under side of the liver, the dark mass to which it is attached : h is the- coronary artery'which supplies the stomach, a, b, c, with blood. The curve of the stomach is well shown: e, e, the arteries which supply the cawl, marked i, i, which falls down from the front of the stomach, over the intestines, like an apron : g, a vessel of the liver. The pancreas is behind the stomach. GALL BLADDER. This is attached to the under side of the liver, shaped like a shot-pouch, and contains between one and two ounces of gall, which is carried to it, as a place of deposit, from the liver. A long slender pipe extends from it to the duodenum, the first portion of the intestines, into which it pours the bile. The use of the bile is to stimulate the intestines, in order to keep them at work. SPLEEN. Anatomists have not discovered the function of this organ. Generally, however, it is admitted to be essentially serviceable to the stomach. The color is red, somewhat like the liver, broad as the palm of the hand, and one or two inches thick. It is in contact with the stomach, in the left side. PANCREAS. Behind the stomach, lying directly across the spine, is the pancreas, a narrow gland, from eight to ten inches long,— which secretes a fluid analogous to the saliva. Through a duct, it is carried onward to be mixed with the bile in the intestine. It is regarded as an auxiliary to digestion. 262 ANATOMICAL CLASS BOOK. KIDNEYS. One of these glands is placed on each side, in the loins, near the spine, a little above the hips.. From the trunk of the aorta, the great artery of the body, two large branches are given off, nearly at right angles, to the kid- neys. A quantity of blood is therefore sent directly into them, from which the urine is separated, and afterwards forced through the ureters, two tubes the size of a writing quill, ten inches or more in length, into the under and back part of the bladder. The urine is separated from the blood by the extreme- ties of the arteries within the substance of the kidney. Having remained a while in the bladder, it excites a desire to void it, — an action effected chiefly by the muscular fibres of the bladder itself, assisted by the abdominal muscles. It is prevented from returning from the bladder to the kidneys, by a valvular structure within, continually closed by the presence of the fluid against th6 valve. ANATOMICAL CLASS BOOK. Fig. 98. Explanation of Fig. 98. In this a and 6 show the tendinous part of the diaphragm or par- tition between the chest and abdomen : d, the kidney, with its fellow 264 ANATOMICAL CLASS BOOK. opposite ; /, the descending aorta; h, an artery given off for tbe in- testinal tube; i where the great artery divides, to send a branch to each leg, g, the ascending great vein, conveying blood to the right side of the heart; c, the capsule, so called, belonging to the kidney, the use of which is unknown; n, the ureter, a tube which conveys the urine from the kidney to the under side of the bladder, where it terminates : the right ureter is seen on that side, also terminating in thevbladder, k; m, I, are arteries; o, is a small artery which runs down on the bone, into the pelvis. STOMACH. Just below the diaphragm, lying nearly horizontally across the top of the abdomen, is the stomach, having the shape of a shot-pouch,—being large at the extremity on the left side, and small where it reaches the right, under the margin of the liver. It presents a curve in front and shorter one on the back side, where it embraces the spine. At the entrance of the ozsophagus, the food tube from the mouth at the large end ofthe orifice is called the car- diac orifice, — because it was supposed by the early anato- mists to be near the heart. Through this the food en- ters the stomach ; and where it makes its exit, into the be- ginning of the intestine, at the other extremity, the opening is the pyloric orifice. A muscle surrounds the neck of the stomach, on the inside, which holds a control over the contents, allowing it to pass onward, or confining it within, according to its state of preparation for digestion. INTESTINES. With a little variation, the whole extent of the intesti- nal tube is six times the length of the body, except in in- fancy, when it averages eight times the height of the child. It is divided into small and large intestines. The small one is further divided into, first, the duodenum, only about a foot long, commencing at the stomach : — into this por- tion the bile and pancreatic juice is delivered. Secondly, ANATOMICAL CLASS BOOK 265 the jejunum, coiled up nearly round the navel: and third- ly, the ileon, the last part of this intestine, joining the cecum, or beginning of the large tract. Usually the diam- eter of this tube is not far from one inch. Secondly, the large intestine is divided in the cecum, a large, irregular membranous sac, with a valve, that ob- structs the return of whatever may have once passed it : the colon, about two inches in diameter, lying near the hip, at the bottom of the abdomen, on the left side, but as- cending in a broad curve towards the stomach, crosses the spine, and dips down into the right side, - describing an arch, — hence this particular part is called the arch of the colon. Finally, the rectum is the last division, a foot long, terminating externally. The inside is beset with the sharp folds of the inner membrane, in the form of shelves, exceedingly numerous, which are termed valvule conniventes. Their express of- fice is to prevent a too rapid exit of the food, in its descent, before all its nutritious substance has been taken by the lacteals. Explanation of Fig. 99. 1. The oesophagus, or swallow perforating 2. The left opening of the dia- phragm. 3. The cardiac orifice of the stomach. 0 4. The small curvature of the 15 stomach. .9 5. The great curvature of tbe stomach. 12 6. The fundus of the stomach. 18 7. The pyloric orifice. 8. The duodenum, divided into three portions. .„ 9. The ascending. 10. The transverse, and '20 n. The descending portion. 12. The jejunum, forming three 23 266 ANATOMICAL CLASS BOOK. fifths of the small intestines, distinguished from the ilium in being: thicker, more vascular, larger, and having more valves. 13. The ilium, forming less than two fifths of the small intestines1, and terminating in the caecum, having two valves at the entrance. 14. The caecum, the first of the large intestines ; situated in the right, having attached to it 15. The appendix vermiformis. The caecum terminating in 16. The ascending portion of the colon, which directs its course from the caecum towards the stomach, connected to the right kidney by a fold of the peritonaeum. 17. The arch of the colon, traversing the abdomen beneath the stomach. 18. The descending portion of the colon, directing its course towards the left region, connected to the left kidney by a fold of the peritonaeum. 19. The sigmoid flexure of the colon, situated in the left iliac re- gion, and terminating in 20. The rectum. MESENTERY. A duplication or fold of the peritona:um,, drawn out as it were from the spine, like a ruffle," is the mesentery, on the border of which the intestines adhere. By this they are supported and kept in place. Nearly in the centre, between where the mesentery attaches itself to the spine and the intestine, are the me- senteric glands, through which the chyle passes in its way to the thoracic duct. DIGESTION. Perhaps no animal process has more deeply engaged the attention of physiologists, than digestion. The fol- lowing remarks embrace, in a few words, all that is known upon the subject. Soon after the food has been admitted into the stomach, considerably softened by the saliva of the mouth and throat, the extremely small aiteries spread in the lining membrane of the stomach, throw out a fluid which is called the gastric juice, which, in addition to the muscular action of the stomach, converts the whole mass into a ANATOMICAL CLASS BOOK. 267 greyish paste. It is rolled forward to the pylorus — the place of passage into the intestine, where there is mixed with it the bile from the gall-bladder, and the juice from the pancreas, both of which dilute it still more. The muscular fibres of the first portion being strong, it agitates and rolls it about, till it assumes the appearance of a thick milky fluid, of the consistence of cream. This part ofthe digestive process, in the first portion of the intestine, is termed chymificalion, and the substance itself chyme. By the peristaltic and vermicular action ofthe intestine, it is carried onward, inch by inch, interrupted by the valves, which throw it from side to side, till every particle is brought into direct contact with the mouths of the lac- teals, everywhere presented. Thus a prodigious extent of absorbent surface is presented to it, through the entire course of nearly thirty feet. Thus, the further the chyme advances, the more closely and certainly is its valuable part taken up by the countless millions of lacteal vessels. They terminate in the me- senteric glands, where it remains a little time, but for what purpose is not precisely understood, and then, by another set of ducts, the fluid is conveyed into the thoracic duct, to be afterwards carried into the vein, in the neck, to be mixed with the blood, and to become blood. The final cause, therefore, of digestion, is to elaborate a material for making blood, from which the whole system is renewed and sustained. Whatever is useless finally passes onward into the large intestine, which, in effect, is a store-house, — in which its stay is temporary, depending on the health, habit and condition of the individual. Three hours after the food is masticated, as a general rule, it passes through the various changes which have been described. Three coats are easily shown, in the walls of the 268 ANATOMICAL CLASS BOOK. stomach and intestines, viz. the peritoneal, the muscular and the mucous. The muscular is a series of fleshy fibres, fine as sewing thread, winding round the cylinder; — lon- gitudinal fibres are also discoverable ; hence there are two particular motions in the intestine. By the contraction of the straight fibres, the intestine is gathered up in wrinkles at different points, through its whole extent, and then elongated again, much like the movement of a worm. By the contraction of the others, it is diminished in diameter at different sections : — thus they are never at rest, but continually moving the chyme from place to place. The first motion is the vermicular, and the second, the peris- taltic. ANATOMICAL CLASS BOOK. 269 THE FLUIDS, OR HYGROLOGY. A variety of fluids are separated from the blood by numerous organs, for various purposes, which are divided into crude, sanguineous, lymphatic, secreted and excremen- tiiious. An example of a crude fluid is found in the chyle; the sanguineous in the blood; the lymphatic in the lymphatic vessels; and the excrementitious, are all such as are expelled from the system as useless. Again, the secreted fluids are further subdivided into the lacteal, as that in the tubes between the intestines and mesenteric glands ; aqueous, in the eye ; mucous, in the nose; albuminous, as the serum of the blood ; oleous, as the fat; and bilious, as exemplified in the bile. LYMPHATICS AND THEIR SECRETIONS. Whenever a moisture exists, either externally or in the obscure cavities of the body, under the skin, among the muscles, in the brain, and indeed where any motion is ef- fected, the lymphatics exist also, though they are invisible. They take up the vapor or fluid and carry it to the tho- racic duct, to be mixed with the blood. If any nutritious 23* 270 ANATOMICAL CLASS BOOK. matter is unnecessarily expended in any of these places, it is sure to be collected again and returned to the circulation. Without these vessels always on the alert, fluids would accumulate beyond the necessities of the organs they were designed to assist, which would inevitably abridge the freedom of action and produce disease. Thus, whatever is superfluous is sent back to the blood, from whence, perhaps, in a majority of cases, it was taken, and if of no further value, it is thrown into the kidneys, and a large portion of it, therefore, is thus conveyed from the body, through the agency of the urinary apparatus. FLUIDS OF THE CRANIUM. A vapor exhales in the ventricles of the brain, secreted by the delicate arteries, to prevent an adhesion ofthe sides, and to keep the contents of the head moist. OF THE NOSTRILS. Part of the mucous in these canals, are the tears passing down the lachrymal duct, from the eyes, adverted to in the anatomy of the eye. Beside this, a congeries of mucipa- rous glands under the lining membrane, also mix their secretions with them to preserve the olfactory nerves from becoming dry, which would destroy their sensibility. No fluid whatever distils from the brain into the nose, as sometimes vulgarly supposed. These are the only sources, even when in excessive quantity, as when labor- ing under a severe cold, whence it arises. OF THE MOUTH. Under the tip ofthe tongue, the angle of each jaw, and lastly, under the ear, between the jaw and neck, are large ANATOMICAL CLASS BOOK* 271 glands, — each secreting a fluid ofthe same character, — the saliva, in quantity sufficient to soften the food for mastication, and to keep the tongue, fauces, sides of the mouth and lips moist and flexible. Such is their ac- tivity, that several ounces are ordinarily collected in the course of one meal. Each gland has a duct leading into the mouth: — the motion of the jaws in chewing and swallowing contributes to the flowing ofthe fluid. 272 ANATOMICAL CLASS BOOK. THE SKIN. Above the muscles, and directly under the skin, is a spongy layer called cellular substance, the cells of which are filled with fat. This cellular covering is enormously thick in whales, and denominated the blubber, which keeps the animal warm. Above this is the true skin, — smooth and delicate on its external surface, but of a looser texture on the under side, where it forms a union with the cellular substance. This true skin is technically called cutis vera. It is profusely supplied with blood vessels, and so numerous are its nerves, that the point of a needle can no where be inserted without wounding one of them. As all the nerves finally run towards the surface of the body, it has led some to the opinion that the true skin was a tissue of nerves and vessels, so intimately inter- woven as to constitute a highly sensitive envelope for the body. The color of the true skin is nearly the same in all races of men, — being as white in the negro as in the European. RETA MUCOSUM. There is spread over the true skin an extremely thin layer of paint, of the consistence of thin size, — which has received the name of reta mucosum, and on this wholly and entirely depends the color or complexion of the indi- ANATOMICAL CLASS BOOK. 273 vidual. In the negro, this mucous paste is jet black; in the Indian copper colored ; in the Spaniard yellowish, but white in the white variety of our species. This pig- ment is constantly flowing out upon the skin, to defend its irritable surface against the combined influence ofthe air, light and heat. These agents, however, exert an action upon the mucous coloring, which dries, becomes hard and insensible, and is continually wearing off, and as con- stantly renewed. SCARF-SKIN. A familiar example of the scarf-skin, the exterior coat of all, is observable in blisters. It is totally insensible, rough and by no means of a uniform thickness. In the palms ofthe hands and soles ofthe feet, it becomes prodi- giously thickened, to defend the tender parts below. This scarf-skin is constantly wearing off, and as constantly re- newed, and hence it is inferred that it is really nothing more than the rete mucosum, thrown off by the action of the excretory vessels. The query may arise, why, if this is the case, are not the palms of the negro's hands perfectly black? They would be so, if the scarf-skin in them had not lost' its vitality. When the negro has suffered from a severe burn, the mouths ofthe ducts, which poured out the coloring matter, are sealed up by the subsequent inflammation, so that no more paint is thrown out, — and the scar remains white. The reason is plain, — the true skin, which is white, is no longer obscured by the black pigment. Rouge, pearl powder, cream of almonds, milk of roses, cologne, spirit of wine, and, indeed, the endless catalogue of cosmetics, which are sold in the shops with the ostensi- ble object of beautifying the skin, are abominable impo- sitions which ought to be interdicted by a strict police regulation, till the happy period arrives when common 274 ANATOMICAL CLASS BOOK. sense is more frequently exercised on the subject of per- sonal appearance. The skin cannot be made permanently whiter, — nor can the hair be stained without injuring it; — a roseate tint cannot be given to the cheek by any pre- paration, that will be abiding. All this class of pretended beautifying articles positively injure the skin, leaving it rougher ; and in old age, in consequence of their habitual application, the face is more thickly wrinkled, and the complexion assumes the hard dead color of bronze. Still worse, the pores are deranged in their functions, and dis- ease may be induced by the absorption of some of the ingredients of those noxious importations, which were never good for any thing but to fill the manufacturer's purse at the expense of those who are willing to be the dupes of their own folly. Cold water is truly a cosmetic — and should be used exclusively. The physiology of the nails, which are supposed to be a production ofthe scarf-skin,— is not well understood. — Writers have not given a satisfactory explanation of their origin or growth. With respect to the hair, its growth bears a striking analogy to vegetables, — inasmuch as it rises from a bul- bous root, imbedded in the skin, into which a gelatinous fluid is secreted. It would be entirely unnecessary to de- tail the opinions of authors on the subject, or to be very particular in relating our own. Hereafter, the physiology of the skin, nails and hair will become the topic of a dis- tinct essay, — with reference to the abuses of the toilet, ANATOMICAL CLASS BOOK. 275 QUESTIONS What is Adenology ? What is the use of glands ? Where is the diaphragm ? What organs are contained within the chest. What is the object of respiration ? How do insects breathe ? Is breathing involuntary in reptiles ? Where is the organ of voice located? How is the larynx formed? Where are the vocal cords found ? What musical instrument does the larynx resemble? What is the object of the thoracic duct r How is the abdomen bounded ? What is the omentum ? Where is the liver placed ? Where is the gall bladder found ? Is the use ofthe spleen known? What is the function ofthe pancreas ? Where are the kidneys lodged? What is the shape ofthe stomach. How is digestion performed ? What is chymification ? What is the use ofthe saliva? How many coats has the stomach? What is hygrology ? 276 ANATOMICAL CLASS BOOK. What are the lymphatics ? Is any fluid found in the brain ? What organs supply fluid to the mouth ? On what does the color of the body depend ? What do you understand by the true skin'? Where is the rete mucosum secreted ? Why is a negro black ? What is the scarf-skin ? How is the hair produced ? Are the nails a production ofthe skin ? Where is the sense of touch most perfect ? Why are there valves in the intestinal tube ? Where is the gastric juice formed ? Where are the lacteal vessels ? What becomes ofthe nutritious part ofthe food ? Are there openings to the stomach ? What is the use of bile or gall ? Of what service is the liver ? How are the intestines kept in place ? Where is the cellular membrane ? Are the lungs separated in the chest ? How are the tones of the voice varied ? What is the glottis ? What prevents food from falling into the wind-pipe ? What is the epiglottis ? By what organs is the voice modulated ? INDEX. Anatomy, . • • Anatomy, comparative, Angiology, . Adenology, Arm bones, Antagonists, of muscles, Absorbents, Auricles, Artery, coronary, Alveus communis, Arteries of the brain, Arteries of the face, Arteries ofthe thigh, Artery of the arm, Air tubes, Auditory nerve, Aorta, . Aqueous humor, Abdomen, '. Bursology, Bones in the Skeleton, Bones in the skull, Bones in the face, Bone ofthe tongue, Bones of the trunk, Bones of the hand, Bones of the leg, . Bones of the foot, Bones of the nose, Breastbone, Bones of the loins, Busks, Blood in muscles, 24 Page. 1 2 2 2 26 57 97 126 131 192 137 136 139 141 245 197 130 216 258 2 3 4 4 5 5 6 6 G 16 22 23 40 58 Blood, circulation'of, Brain, insensible, Brain of worms, Brajn, structure of, Breathing of fishes, Breathing of shell fish, Both eyes see but one object, 232 Cylindrical bones, Clavicle, Connexion of bones, Cheek bones, . Carpus, Corsets, . Cutting teeth, Chewing tobacco, Catalogue of muscles, Cavities of the heart, Compound lever, Carotid artery, Capillaries. . Contraction of arteries, Circulation of the blood Crassamentum, Color of the blood, Cerebrum, Coverings of the brain, Caterpillar, Clam, . Cause of voice, Cosmetics, Cochlea, Coats of the eye, . Ciliary processes, 115 158 160 156 247 248 2 5 9 16 28 40 41 42 59 122 191 134 140 142 145 149 149 153 155 246 248 257 273 196 209 213 278 INDEX. Page. Page. Choroides, 210 Heart, shape of, 122 Cornea, . . 211 Heart-case, 132 Cataract, 219 Heart-case, use of, . 132 Convex spectacles, . 228 Hearing of insects, 176 Concave glasses, . 230 Hydrocanthiri, 246 Cross-eye, . 233 Humors of the eye, . 216 Distortion of the bones, 37 Hair, .... 272 Double heart, 121 Instep, . 32 Double heart, plan of 125 Involuntary muscles, 53 Diastole of the heart, . 130 Irritability of muscles, 56 Dorsal nerves, 166 Influence of the nerves, 59 Drum of the ear, . 182 Imposition in bone setting, 107 Dr Darwin's opinion of deaf- Internal cords ofthe heart, 126 ness, 192 Intercostal nerves, 157 Diagram of the heart, . 147 Involuntary nerves, 163 Dura mater, 155 Intestines, 263 Diaphragm, . 243 Image inverted in the eye , 231 Deafness, partial, . 202 Iris, 212 Deafness, permanent, . 202 Joints, 114 Epiphises, 3 Jugular vein, . 139 Enamel ofthe teeth, 41 Knee, security of, 103 Extensors of the toes, 106 Kidneys, 261 Ear, 175 Lower jaw, 17 External ear, 176 Ligaments, 45 Ear wax, . 180 Ligaments ofthe knee, 46 Eustachian tube, 185 Ligaments of the hand, 47 Error loci, . 150 Ligaments of the foot, . 48 Ear, diseases of, 201 Lumbar abscess, 75 Ear ach, . 201 Lacing, 77 Eye, . . 205 Latissimus muscle, . 82 Flat bones, 2 Lesser circulation, 124 Finger bones, 29 Left heart filled at death, 124 Female skeleton, 36 Little bones of the ear, 188 Friction, prevention of, 57 Little brain, 153 Face, muscles of, 60 Lobes of the brain, . 154 Fascia of the arm, 91 Lungs, 243 Fluids, 115 Lizards, aquatic, . 249 Frog's heart, . 126 Lungs of reptiles, 249 Force ofthe auricle, 129 Lungs of frogs, 250 Food-pipe, . 257 Language, . 253 Growth of the bones, 35 Larynx, 254 Greater circulation, 124 Liver, 258 Glands of the ear tube, 181 Lens, crystaline, . 218 Gall-bladder, 260 Myology, 2 Globe ofthe eye, . 206 Metacarpus, 28 Hygrology, . 2 Muscles, physiology of, 50 Hip bones, 24 Muscles, number of, 51 Hand, bones of, 28 Muscles, shape of, 52 Heart of vermin, . 119 Muscles, two orders of, 55 Heart of fishes, . 119 Muscles never weary, 55 INDEX. 279 Muscles of the ear, Muscles of the neck, Muscles of the jaws, Muscles of the throat, Muscles of the abdomen, Muscles ofthe pelvis, Muscles ofthe chest, . Muscles of the back, Muscles of the arm, Muscles of the thigh, Muscles of the foot, Motion of the heart, Mechanism of the nerves, Musical ear, Membrana Nictitans, Names of muscles, Nerves of the thigh, Notions of the ancients, . Nerves of the heart, Nerves, Nerves of the foot, Nerves ofthe arm, Nerves accompany arteries, Nine pair of nerves, Nerves ofthe face, Nerves ofthe eye, Nerve of the tongue, Nymphae of gnats, Nerves of a perch, Near sightedness, Neuts, Osteology, Os frontis, Occipital bone, Os hyoides, Olfactory nerves, Optic nerves, Oval window, Oyster, how it lives on land, Omentum, Optic nerve, Processes, Palate bones, Periosteum, Practice of muscles, Pronator muscles, Power of the left heart, Position of the heart, Primative artery, Pia mater, Page. 64 Pleura, 66 Pancreas, 66 Pupils of albinos red, 70 Ribs, 72 Roots of teeth, 74 Round window, 76 Rete mucosum, 80 Syndesmology, 86 Splanchnology, 96 Skeleton, 104 Sesamoid bones, 123 Structure of bones, . 158 Seive bone, 200 Sutures of the head, 226 Spine, 101 Shoulder, 102 Small waist, 117 Sugar, effects of on teeth 131 Suspended animation, . 153 Strength of the right arm, 158 Supinator muscles, . 168 Sole of the foot, . 163 Single heart, 164 Spinal marrow, 168 Sympathetic nerve, 169 Senses, 171 Semicircular canal, 246 Stapes, 247 Spiracula, 229 Spallanzani, 250 Spleen, 2 Stomach, 10 Seeing in the'dark, ] 2 Seeing in water, 18 Smelling, 167 Socket of the eye, 167 Sclerotica, 186 Scarf skin, . 248 Teeth, number of, 258 Temporal bone, 222 Tear bones, 3 Tibiae, 17 Thigh bone, 34 Teeth, 54 Tendons, 92 Two sets of blood vessels, 124 Tube of the ear, 133 Tympanum, 135 Tasting, 156 Thyroid Cartilage, Page. 148 260 234 21 41 186 270 2 2 3 280 INDEX. Page. Thymus gland, 257 Thoracic duct, . 258 The eye adapts itself to dis tan- ces, 237 Tears, 227 True skin, 270 Upper jaw bones, 16 Vertebra?, 19 Voluntary muscles, 53 Ventricles of the heart, 126 Vena cava, 127 Valves of the heart, 130 Vestibule, 191 Veins, . . , 143 Page. Veins of the leg, 144 Vitality of the blood, 148 Viscera of the chest, . 142 Voluntary respiration, . 244 Vermin, 245 Voice of animals, 251 Voice of man, , 253 Vocal strings, 256 Valves of th 'ntestiaes, . 264 Wall bones, . 12 Wedge bone, . 12 Wrist, bones of, 27 Wisdom teeth, 41 Warm blooded animals, 120 '^O^ I I 2 2 1 11 !0 v \ vw rw » A H0AIVB8I1 IVNOIIVN 3 N I 3 I 0 3 W JO A B V B 9 I 1 IVNOIIVN 1NI3IQ3W JO ABVB J -' ^ O.IIRARY OF MEDICINE NATIONAl LIBRARY OF MEDICINE NATIONAL LIBRARY MOABValll IVNOIIVN 3NI3I03W 30 ABVBBI1 IVNOIIVN 3NI3IQ3W JO ABVB HONE NATIONAL LIBRARY OF MEDICINE N A T I O N A I 11 B R A R Y O F M E D I C . 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