Neck. 1. Latissimus colli, or platysma myoides; 2. sterno-cleido-mastoideus.

Tongue and thyroid cartilage.-1. Omohyoideus; 2. sternohyoideus; 3. sternothy. reoideus; 4. hyothyreoideus; 5. musculus glandula thyreoidea; 6. stylohyoideus; 7. styloglossus; 8. mylohyoideus; 9. geniohyoideus; 10. hyoglossus; 11. genioglossus; 12. lingualis.

Muscles of the pharynx and palate.-1. Stylopharyngeus; 2. constrictor pharyngis superior; 3. constrictor medius; 4. constrictor inferior; 5. salpingo-pharyngeus; 6. palato-pharyngeus; 7. constrictor isthmi faucium; 8. levator palati mollis; 9. circumflexus palati; 10. azygus uvulæ.

Muscles of the larynx.-1. Cricothyreoideus; 2. crico-arytenoideus posticus; 3. crico-arytenoideus lateralis; 4. arytenoideus obliquus; 5. arytenoideus transversus ; 6. thyreo-arytenoideus; 7. thyreo-epiglotticns.

The whole number of muscles about the head, neck, and throat, is therefore 72.

Muscles of the abdomen.—1. Obliquus externus abdominis; 2. obliquus internus abdominis; 3. transversalis abdominis; 4. rectus abdominis; 5. pyramidalis; 6. diaphragma or septum transversum.

Muscles of the thorax.-1. Sterno costalis, or triangularis sterni; 2. serratus posticus superior; 3. serratus posticus inferior; 4, 5, 6. scalenus anterior, medius, and posterior; 7 to 18. levatores breviores costarum; 19 to 21. levatores longiores costarum; 22. intercostales externi; 23. intercostales interni; 24. quadratus lumborum.

Muscles moving the head and spine.-1. Splenius capitis; 2. splenius cervicis; 3. biventer cervicis; 4. complexus; 5. trachelomastoideus; 6. transversus cervicis; 7. cervicis descendens; 8. longissimus dorsi; 9. sacrolumbalis; 10. spinalis cervicis; 11. spinalis dorsi; 12. multifidus spinæ; 13 to 22. interspinales cervicis; 23 to 28. interspinales lumborum; 29. rectus capitis posticus major; 30. rectus capitis posticus minor; 31. obliquus capitis superior: 32. obliquus capitis inferior; 33. rectus lateralis; 34. rectus capitis anticus major; 35. rectus anticus minor; 36. longus colli; 37 to 43. intertransversi colli priores; 44 to 49. intertransversi colli posteriores; 50 to 57. intertransversi dorsi; 58 to 62. intertransversi lumborum.

Muscles of the anus and perineum.-1. transversus perinei; 2. transversus perinei alter; 3. sphincter ani; 4. levator ani; 5. musculus coccygeus; 6. curvator coccygis.

Muscles peculiar to the male organs of ge neration.-1. Cremaster; 2. erector penis 3. accelerator; 4. compressor prostatæ.

Muscles peculiar to the female organs of generation.-1. Erector clitoridis; 2. sphincter vaginæ; 3. depressor urethræ.

The whole number of muscles of the trunk 105.

Muscles of the upper extremity.--Shoulder. 1. Pectoralis major; 2. pectoralis minor; 3. subclavius; 4. serratus magnus; 5. trapezius; 6. latissimus dorsi; 7. rhomboideus minor; 8. rhomboideus major; 9. levator anguli scapula; 10. deltoides; 11. supraspinatus; 12. infraspinatus; 13. teres major; 14. teres minor; 15. subscapularis.

Arm.-1. Biceps flexor cubiti; 2. brachialis internus; 3. coracobrachialis; 4. triceps extensor cubiti; 5. anconeus.

Fore-arm.-1. Supinator radii longus; 2, 3. extensor carpi radialis longior et brevior; 4. extensor carpi ulnaris; 5. extensor communis digitorum manus; 6. extensor proprius auricularis; 7. abductor longus pollicis manus; 8. extensor major pollicis manus; 9. extensor minor pollicis; 10. indicator; 11. flexor carpi ulnaris; 12. palmaris longus ; 13. flexor carpi radialis; 14. pronator radii teres; 15. flexor digitorum sublimis, or perforatus; 16. flexor profundus, or perforans; 17, to 20. musculi lumbricales; 21. flexor longus pollicis manus; 22. supinator radii brevis; 23. pronator radii quadratus.

Muscles of the hand.-1. Abductor brevis pollicis manus; 2. opponens pollicis manus; 3. flexor brevis pollicis; 4. adductor pollicis; 5. palmaris brevis; 6. abductor digiti minimi; 7. flexor proprius digiti minimi; 8. adductor ossis metacarpi digiti minimi; 9, to 11. interossei interni manus; 12, to 15. interossei externi manus.

The muscles of the upper extremity

are 58.

Muscles of the thigh.-1. Tensor fascia latæ; 2. gluteus maximus; 3. gluteus medius; 4. gluteus minimus; 5. pyriformis; 6, 7. geminus superior and inferior; 8. obturator internus; 9. quadratus femoris ; 10. biceps flexor cruris; 11. semitendinosus; 12. semimembranosus; 13. psoas minor; 14. psoas major; 15. iliacus internns; 16. sartorius; 17. gracilis ; 18. rectus extensor cruris; 19. vastus externus; 20. vastus internus; 21. cruralis; 22. pectineus ; 23. triceps adductor femoris ; 24. obturator externus.

Muscles of the leg.-1. Gastrocnemius or gemellus; 2. soleus; 3. plantaris; 4. pop

liteus; 5. flexor longus digitorum pedis; 6 to 9. lumbricales pedis; 10. flexor longus hallucis; 11. tibialis posticus; 12. peroneus longus; 13. peroneus brevis; 14. tibialis anticus; 15. extensor longus digitorum pedis; 16. peroneus tertius.

Muscles of the foot.-1. Extensor proprius hallucis; 2. extensor brevis digitorum pedis ; 3. flexor brevis digitorum pedis; 4. abductor hallucis; 5. transversus pedis; 6. abductor digiti minimi pedis; 7. flexor brevis digiti minimi pedis; 8 to 10. interossei interni pedis; 11 to 14. interossei externi pedis.

The muscles of the lower extremity are 54; and the whole number of the body 289. But as they are the same on both sides, this must be doubled, which will give 578; an enumeration which is pretty nearly correct.

ORGANS CONCERNED IN THE REDUCTION AND ASSIMILATION OF THE FOOD.

Organs of mastication and deglutition. The two jaws, with their teeth, and the tongue, are the principal agents in the business of mastication.

The articulation of the condyle of the lower jaw with the glenoid cavity of the temporal bone, admits of the former part being moved in various directions. Its depression and elevation cause the opening and shutting of the mouth. It can be brought forwards, and carried backwards; and admits also of being moved to one side or the other. It is by a combination of these various motions that the food is masticated, or reduced into a soft and pulpy form. The different teeth, which are placed in various parts of the cavity of the mouth, are adapted, by their form and situation, for various parts of the process of mastication. The anterior ones, which have a thin cutting edge, and in which the superior overlap the inferior, act like the blades of a pair of scissars. These cut the food into smaller morsels; and serve us also in biting off a portion from any mass of food which we may be eating. The back teeth have broad bases, furnished with obtuse prominences; and they shut perpendicularly on each other. These are therefore well adapt ed for the grinding and trituration of the food. As their office requires a greater muscular force, they are placed in the back of the mouth, near to the centre of motion, and where, consequently, the action of the muscles is felt with the greatest effect. The catting teeth are placed in front, at a

greater distance from the attachment of the muscles, because their oflice does not require so great a muscular exertion.

The tongue is of considerable utility in contributing to mastication, as it serves to move the food about in the cavity of the mouth, and to subject it again to the action of the grinding teeth, when it has escaped from between their surfaces. The muscles of this organ, which we have enumerated in the myological division of the article, give it a power of motion in every direction.

But the simple act of mastication would only reduce the food into a powder, or at all events into a dry mass, that could not be swallowed without great difficulty. To obviate this inconvenience, it is plentifully moistened with a watery fluid called saliva, and is thereby converted into a soft paste, which can be conveyed into the stomach with perfect facility. The source of this fluid is in several glandular bodies situated near the mouth, and sending excretory ducts which convey the secreted fluid into that cavity. As the jaws move, their muscles compress these glands, and squeeze the secreted fluid into the mouth. The tongue is constantly employed in bringing again under the action of the teeth those portions of the food which escape from between them; and the closure of the lips prevents it from falling out of the mouth.

The true salivary glands are three in number, on each side of the head. The largest is placed in the space left between the ear and the lower jaw-bone; and is called, from its situation, the parotid. Its duct pierces the middle of the cheek. The two others are placed under the tongue, and are called the submaxillary and sublingual. Their ducts join to open by a common orifice, at the side of the membrane called the frenum of the tongue, which ties the under surface of that organ to the inside of the lower jaw. Besides these large salivary glands, there are other small granular bodies, which pour a mucuous fluid into the mouth; these are named, according to their situation, glandulæ labiales, buccales, &c.

The cavity of the mouth, in which the process of mastication goes on, is not a very extensive one. There is a small space left between the cheeks and the teeth externally; but within the teeth the tongue occupies nearly the whole room. The upper boundary is formed by the palate or roof of the mouth, and the lower by the surface of the tongue. The mouth opens behind by a tolerably fire communication, into a mem

branous bag, called the pharynx. The surface of the mouth is every where covered by a soft and smooth membrane. This is of course kept constantly in a moist state, as the glands above enumerated continually pour more or less of their secretion into the cavity. The membrane of the mouth is continuous with the external surface of the body; but the skin assumes a more delicate organization, as must be apparent to every body, from the change of colour at the lips.

Bag of the pharynx.-The masticated aliment is collected on the back of the tongue, which is then carried upwards, and back wards to discharge it into the pharynx. This bag is covered by muscular fibres (forming the muscles called constrictores pharyngis) which contract, successively, in order to propel the food towards the stomach. But as there are several organs communicating with the pharynx, the food might pass in a wrong direction if the parts were not so contrived as to prevent such occurrences.

In the upper and anterior part of the pharynx, the nostrils open by two large and free apertures. Between these and the entrance from the mouth, is found a fleshy and moveable curtain, called the soft palate, or velum pendulum palati. There is a small body of a pointed figure projecting from the middle of this organ, and known by the name of the uvula. This curtain and the uvula can be easily seen in the throat of a living person. It admits of being elevated so as to shut the opening of the nostrils; and its action is exemplified in the act of vomiting: the food is forcibly thrown into the pharynx, and would pass mostly into the nose, were it not prevented by the soft palate. From the uvula the membrane is continued on either side, in an arched form, towards the root of the tongue, and it contains a glandular body called the tonsil, which secretes a mucous fluid to lubricate the parts, and facilitate the passage of the aliment. The larynx opens into the pharynx, just at the root of the tongue; over this part, which is termed the glottis, every morsel of the food must necessarily pass; yet, so exquisitely tender is the membrane of the windpipe, that the contact of the smallest extraneous body excites a convulsive paroxysm of coughing that does not cease until the offending matter be removed. Here then are two objects to be effected; the function of respiration requires that the windpipe should have a free coinmunication with the external air, while the irritable nature of its membrane demands that no ex

traneous body should find admission. These points are both attained by means of a strictly mechanical contrivance; by a structure which produces the required effect, independently of the will of the animal, and merely in consequence of those motions which the organs perform in the office of deglutition. At the back of the tongue, and just in front of the glottis, is a cartilaginous valve called the epiglottis. When the parts are at rest, this valve stands perpendicular, and consequently does not interfere with the passage of air into the windpipe. In the act of swallowing, the tongue, is carried backwards, and the windpipe is drawn up: hence the epiglottis becomes mechanically applied over the opening, and at this moment the food enters the pharynx over it, and by its pressure closes the aperture still more completely. As soon as the food has passed, the tongue and windpipe resume their former position, the elasticity of the cartillage restores it to the erect state, and the glottis is again free for the continuance of respiration. So completely does this simple mechanism answer the proposed end, that although every morsel of food passes over the glottis, the accident of any portion going the wrong way, as it is termed, is comparatively rare, and can only arise from our being imprudent enough to laugh or talk while we are swallowing. In either of these cases air must pass out of the trachea, and by so doing, it lifts up the epiglottis.

The pharynx opens below into the œso phagus, a muscular tube, which conveys the food into the stomach. The aliment in its farther progress, goes through different viscera contained in the abdomen; and we shall therefore proceed with a description of that cavity.

The term abdomen includes a large portion of the body. It is bounded above by the cartilages of the ribs, and by the diaphragm, which separates it from the chest ; at the back part, by the bodies of the lumbar vertebra; in front and at the sides, by the abdominal muscles; and below, by the bones of the pelvis.

It is every where lined by a membrane called the peritoneum. The surface of this is perfectly smooth and polished, and moistened by a serous exhalation produced by the minute arteries of the part. This membrane not only lines the cavity of the abdomen, but also covers all the viscera contained in that cavity, so that the exterior surface of each part consists of what anatomists

call its peritoneal coat. Hence the motions of these parts upon each other, and upon the surface of the cavity are performed with perfect facility. The productions of the membrane, which give these exterior investments to the viscera, serve also to confine them in their relative positions.

The cavity is subdivided into three regions, the epigastric, which includes all the space above an imaginary line drawn across the belly, from the greatest convexities of the car tilages of the seventh true rib; the umbilical, which is the division between this line and another drawn from the anterior superior spines of the ilia; and the hypogastric, which is the space left below the last line.

The sides of the epigastric region, which are the spaces covered by the cartilages of the ribs, are called hypochondria: the sides of the umbilical region are named the loins: and those of the hypogastric the groins.

The stomach is a large membraneous reservoir, receiving the food from the esophagus, and retaining it until a certain change, called digestion, is produced. Its figure is conical, as it is largest at the left end, and gradually decreases in size towards the right: these are called the greater and smaller extremi ties of the stomach. It is also bent in its course, so that we describe a greater and smaller curvature or arch. It has two openings, one close to the diaphragm, called the cardiac, superior, or œsophageal; the other just at the smaller end is called the pyloric, or lower orifice. The capacity of the stomach varies from about 5 to 11 pints.

Its structure is muscular; and this is necessary in order to propel the food when digested. Under the muscular coat is found the internal, or villous tunic, the arteries of which pour out the gastric juice, the chief agent in the digestion of the food.

The pylorus, which word is derived from two Greek terms, signifying the keeper of the gate, is a contracted ring, by which the stomach communicates with the small intestine. It prevents the food from passing out of the stomach, before it has been sufficiently acted on by the gastric juice.

The stomach receives a portion of peritoneum as the esophagus passes the diaphragm. There is also a process coming from the liver, called the lesser omentum, or mesogaster. This is attached to the lesser arch of the stomach. The great omentum, or the caul, is affixed to the greater arch of the stomach, and hangs from thence over the surface of the intestines; being interposed between them and the intestines. It is also

attached to a part of the colon; its use is unknown.

The small intestine is divided into three parts; the duodenum, jejunum, and ileum: but this distinction is an arbitrary one, and not founded on any difference in structure. It consists of a membranous tube, about an inch or an inch and a half in diameter, and four times the length of the subject. Notwithstanding this great length, it is collected by means of numerous turnings and convolutions, into a comparatively small space. These convolutions of the small intestine occupy the chief part of the umbilical and hypogastric regions of the abdomen. They are connected in their situation by means of a broad folded membrane, called the mesentery. This production of the peritoneum is about six inches broad at its commencement, but it expands gradually, something after the manner of a fan, so that it becomes broad enough, ultimately, to cover the whole length of the small intestine. serves to keep the different convolutions of the canal in a certain relative position, and allows, at the same time, a considerable freedom of motion, without any danger of intangling. In tracing the course of the small intestine, we follow the duodenum from the lesser extremity of the stomach, in the right hypochondrium, making three turns close on the backbone, and then coming out just over the left kidney. The general direction of the canal from this point, independently of its various turnings and windings, is towards the right groin, where the ileum terminates by entering the cœcum.

It

The small intestine possesses three coats similar to those of the stomach: viz. an external or peritoneal; a middle or muscular; and an internal or villous tunic. The latter forms a great many transverse, loose, and floating processes, called valvulæ conniventes; by means of which the extent of surface of the villous coat is very much augmented. Numerous glandular bodies are found in parts of the canal, collected into small parcels, and hence called glandulæ agminatæ.

The food which is reduced by the action of the stomach into an homogeneous mass, called chyme, enters the small intestine, where it undergoes a further change, and becomes chyle. It is propelled along the canal by the muscular coat of the intestine, and the villous tunic absorbs from it the nutritious particles. It passes along every turn and winding of this long canal, continually subjected to the action of the absorbing vessels. The residue of the alimentary mat

ter is sent into the large intestine, from which it is expelled in the form of fæces.

The large intestine is a canal of about two or three inches in diameter, and seven feet in length. It is divided into the cœcum, colon, and rectum. The cœcum is a bag situated in the right groin, and receiving the termination of the ileum. The latter intestine enters in such a manner that the passage of the aliment is allowed from it into the cæcum, but prevented from returning. The part which effects this is called the valvula coli. A small process, about equal in size to an earthworm, is connected to the cœcum. It is called appendix cæci vermiformis, and its use is unknown.

From the right groin the intestine ascends on the right side of the abdomen over the kidney, under the name of colon: it turns completely over the abdomen at the upper part, and descends along the left side to the left groin; here it makes a large turn over the brim of the pelvis, and enters that cavity, where it takes the name of rectum, which terminates at the anus. We distinguish in the colon, the right or ascending portion; the middle or transverse arch; the left or descending; and the sigmoid flexure. The right and left portions of this gut are closely bound down in their situations, by two portions of peritoneum, called ligamenta coli. The transverse arch has a broad process connected to it, by which it is loosely attached: this is called the mesocolon.

The large intestines have a peritoneal, a muscular, and a villous coat; but they have no valvulæ conniventes. The longitudinal muscular fibres are collected into three bands, which being shorter than the rest of the intestine, occasion the other coats to be gathered up in folds between them, and thereby give the intestine a sacculated appearance.

The residue of the alimentary matter, which the large intestine receives from the small, is converted in the former canal into a substance of peculiar odour, colour, and consistence, called fæces; in which form it is expelled from the body.

Parts subservient to the functions of the alimentary canal, and contained in the cavity of the abdomen.

The liver is the largest glandular mass in the body, and is placed towards the right side of the epigastric region. Its thickest portion fills the right hypochondrium; a thinner part of the gland extends across the middle of the epigastric region to the left

hypochondrium. Its size is greater in proporas the animal is younger. In the adult it is contained within the cartilages of the ribs; but in the foetus it extends to the navel, and fills half the belly. Its upper surface is convex, and in close contact with the concave under surface of the diaphragm. Its under or concave surface rests chiefly on the stomach. It is divided into a right and left lobe, and lobulus spigelii. It has a posterior and thick, an anterior and thin margin. Its colour, in the most healthy state, is of a reddish brown; but it often deviates from this. Its weight, in an adult man of middling stature, is about 3 pounds. It is connected to the diaphragm by four ligaments: riz. 1. ligamentum latum, or suspensorium, which divides the right and left lobes from each other. The front edge of this part contains the fibrous remains of the umbilical cord of the fœtus, which assuming the appearance of a round rope, is called the round ligament. 2, 3. Ligamenta lateralia, or dextrum, et sinistrum. 4. Ligamentum coronarium.

The liver is covered exteriorly by peritoneum, and there are certain fissures and excavations on its surface. 1. Fossa, for the gall-bladder, in the under surface of the right lobe. 2. Fissure on the anterior, thin margin for the entrance of the umbilical vein. 3. Portæ, or large transverse notch, at which the blood-vessels enter, and from which the hepatic duct proceeds. 4. Notch' for the inferior vena cava. 5. Excavation for the bodies of the vertebræ.

The liver is composed of a tolerably firm and close substance, consisting of a closely united congeries of different vessels. These vessels are the vena portarum, the hepatic artery, the hepatic veins, and the biliary ducts. The former vessel carries to the liver the blood which has circulated through the different abdominal viscera. It ramifies in the liver like an artery, and the secretion of the bile is supposed to take place from the blood, which it conveys to the liver. The blood of this vein, as well as that brought by the hepatic artery, for the nourishment of the liver, is returned by the large hepatic veins to the inferior vena cava. The small branches of the hepatic duct which conveys the secreted bile from the liver, appear like small yellow pores, when a section of the liver is made, and hence they are called pori biliarii.

The mesogaster or little omentum, is attached to the portæ of the liver. The vena portarum, the biliary ducts, the hepatic artery, and the hepatic plexus of nerves,