ANATOMY. m

curvatures, one large, which runs along the greatest convexity ;and one small, directly opposite to the tonu/r. The stomach hastwo openings, called its orifices; one between the great extremityand tn,: small curvature; the other at the end of the small or con-tracted extr. niity. The f.rsl opening; named curdia, is a con-tinuation 01 the u-sopnegus; the other joins the intestinal canal,and is caned pylorus. 'I’he aliment passes down the {esophagus,into the stomach, throw git the cavdia, and, after being digestedpasses through the pylorus, where the intestinal canal begins.The great extremity of the stomach is in the left, hypochondritun,and close under the diaphragm. Vet tire superior orilice is notin the left hypochondrunn, hut almost opposite to, and very nearthe middle oi, the bodies of the lowest vertebrae of the hack. Itssmall extremity floes not reach to the right hypochondritun, butbends obliquely backwards toward the upper orilice; so that thepylorus lies about two lingers breadth from the body of the ver-tebra; immediately under the small portion of the. liver. Thestomach is composed of four tunics or coats, so intimately con-nected together, that it requires no little dexterity in the anatomistto demon irate them. The exterior one is membranous, beingderived from the periten;rum. The second is a muscular tunic,composed ot fleshy fibres, which are in the greatest number aboutthe two orifices. The third is called the. nervous coat, and withinthis is the villous or velvet-iike coat, which composes the insideof the stomach. The two lart coats being more extensive thanflit two tirst, from the fold,, which are observed every where inthe cavity of this visetts, and more particularly about the pylorus ;where they seem to impede the too hasty exclusion of the aliment,making a considerable plait, called valvula pylori. 'The innercoat is constantly moistened by a mucus, which approaches to thenature of the saliva, and is called the gastric juice; this liquor hasbeen supposed to be secreted by certain minute glands seated inthe nervous tunic, whose excretory ducts open the surface of thevillous coat. After the food has remained from one to threehour, in the stomach, it is converted into a greyish pulp, calledchymus, and some few milky particles begin to appear. 'Thetime of its residence in this bag is proportioned to the nature ofthe aliment, and the state of the stomach and its juices. Thethinner and more perfectly digested parts pass by a little at a timeinto tiie duodenum ; while the grosser and less digested particlesremain in the stomach, till they acquire a sufficient degree offluidity to pass into the intestines, where the nature of this pulp isperfectly changed. 'The bile and pancreatic juice which flow' intothe duodenum, and the mucus, which is every where distilledfrom the surface of the intestines, mingle with the ejected matter,and still farther attenuate and dissolve it. Two substances, verydifferent from each other in their nature and destination, are theresult uf this combination. One of these, which is composed ofthe liquid parts of the aliment, and of some of its more solid par-tic bis, extremely divided and mixed with the juices we have de-scribed, constitutes a very mild, sweet, and whitish fluid, resemblingm:ik, and distinguished by the name of chyle. 'This fluid is ab-sorbed by the lacteal vessels, which convey it into the circulation,where, by being assimilated into the nature of blood, it affordsthat supply of nutrition, which the continual waste of the bodyrequires. 'The other is tile remains of the alimentary mass, de-prived of all its nutritious particles, and containing only such partsas were rejected i>v the absorbing mouths of the lacteals. 'Thisgrosser part, called tiie face-:, passes on through the course of theintestines, and is voided at the anus.

3 . The Intestinal Canal is live or six times as long as thebody, and forms many circumvolutions in the eavitv of the abdo-men, which it traverses from the right to the left, and again fromthe left to the right; in one place descending, and in anotherextending itself upwards. The inner coats of the intestines, beingmore capacious than their exterior tunics, form a multitude ofplaits, placed at certain distances, and called valvukc conniventes.Now this disposition will be found to afford a farther proof of thatdivine wisdom, which the anatomist and physiologist may discoverin all their pursuits.—For if the intestinal canal was much shorterthan it naturally is, if it passed in a direct course from theslomaeh,and if its inner surface was destitute of valves;. the aliment wouldpass with great rapidity to the anus, and sufficient time would bewanting to assimilate the chyle, and absorb it into the lacteals;so that the body would be deprived of the supply of nutrition,which is so essential to life and health. 'This canal is divided into

■ mall and large intestines; the former being distinguished by thenames ot duodenum, jejunum, and ilium; and the latter bv thoseot circuni, colon, and rectum. The former (ill the middle andfore-parts of the belly: the latter the sides, and the upper andlower parts.

'The Duodenum is so named, because it is about twelve incheslong. It begins irom the pylorus at the extremity of the stomach,and is thence reflected downwards. It first passes by the gall-bladder, then under the following gut and mesenterv, and comingonce more in sight in the left liypochondium, it there commencesjejunum, which is the second of the small intestines.

The Jejunum is so called from its being found for the mostpart empty. It is situated in the regio umbilical is, and makessomewhat more than a third part of lire small intestines. Jt isdistinguished from the next succeeding intestine by its coats,which are somewhat thinner and less pale.

The Ilium is a continuation of the former gut. It is situatedin the hypogastrium, and very often some_part of it passes into thepelvis, and lies upon the urinary bladder, especially in women.It enters the colon on the right side, near the upper edge, of theos ilium.

The large circumvolution of the ilium covers the first of thelarge intesiines, called the Caecum, which seems properly to be-long to the colon, being a kind of pouch of about four lingerswide, and nearly of the same length; having exteriorly a littleappendix, called appendix exei, or the vermiform appendix, fromits resemblance to a worm.

'The Colon ascends by the right kidney, to which it is attached;passes under the hollow part of the liver, and the bottom of thestomach, from the right hypochondrium to the left, and thencedescends into the pelvis at the place where the appendix ca'iijoins it. One portion of the circumference of both is depressed,and forms a large fold on the inside, which advances into the ca-vity of the intestine, and gets the name of valve of the colon.Thence the colon passes down towards the os sacrum, where thecanal takes the name of rectum.

The K ectum, or Straight Gut, is the last of all the intestines'.It is so named, because when viewed directly forward, it appearsto run down in a straight course from the last vertebra of the loins,on the lore-side of the os sacrum, all the way' to the os coccygis,where it ends in the anus. This intestine, properly speaking, isa true continuation of the last convolution of the colon; aiid it isthe repository and common sewer of the whole intestinal canal.The figure of the rectum varies according as it is full or empty.

The extremity of the intestine which forms the anus lias-severalmuscles belonging to it, some surrounding it like spliinclers; therest broad fleshy planes inserted in it, and which, being likewise,fixed to other parts, sustain it in its natural situation, and restoreit to that situation, after being disturbed by the force necessary forthe exclusion of the feces.-

All the intestines have the same coats with (lie stomach ; thefibres of their middle or muscular coats are circular, or spiral,and longitudinal ; of the latter indeed blit very' few. “The an-tagonists to these muscular fibres of the stomach and guts areformed l>v their contents, which are pressed from one place toanother, and the muscles of the abdomen; far these also pressingupon them alter their form into one less capacious, which neces-sarily extends their circular fibres. The large intestines havethree membranes or ligaments on the outside, running their wholelength, and supporting the sacculi, into which those interstices aredivided. The lesser intestines have, at very small distances, se-milunar valves placed opposite to the interstices of each other, toprevent tiie aliment from passing too speedily through them; andthe better to answer that end, they are larger and more numerousnear the stomach, where tiie food is thinner, than thev are towardsthe colon, where the food is continually made thicker in its pro-gress, by a discharge of part of tiie chyle.

At tiie entrance of the ilium into the colon are two very largevalves, which effectually hinder the regress of the feces Into theilium.

The intestines are not left to move at.random in the cavity oftiie abdomen ; but are carefully bound down by a membranousweb, which prevents the intestinal convolutions from being intan-gled in each other, and yet allows them a gentle, floating,' but li-mited motion.—This web, which is called the Mesentery, isdistinguished into two portions; one very broad, and much

plaited.