Page:Encyclopædia Britannica, first edition - Volume I, A-B.pdf/316

 z(>6 A N A T rior, the other pollerior; and two extremities, one large, which reprefents the baiis of a tongue, and one fmall and a little rounded like the point of a tongue. The pancreas is fituated tranfverfely under the ftomach-, in the duplicature of the pofterior portion of the mefocolon. The large extremity is connected to the fir ft incurvation of the duodenum, and from thence it pafles before the reft of that inteftine, ail the way to its laft incurvation ; fo that a great part of the duodenum lies between the pancreas and the vertebrae of the' back. The fmall extremity is fixed to the omentum near the fpleen. The pancreas is compofed of a great number of foft glandular molecule, combined in fuch a manner, as to exhibit the appearance of one uniform mafs on the outride, the furface of which is rendered uneven only by numerous fmall convexities, more or lefs flatted. When thefe moleculse are feparated a little from each other, we find along the middle of the breadth of the pancreas, a particular dudt, in which feveral fmaller dudts terminate laterally on each lide, like fmall rami in a ftem. This canal, named duttus pancreaticus, or duttus Virfungi, is very thin, white, and almoft tranfparept, and the extremity of the trunk opens commonly into the extremity of the ducfus cholidochus. From thence it diminifhes gradually, and terminates in a point, next the fpleen. The fmall lateral branches are likewife pretty large near the- trunk, and very fmall toward the edges of the pancreas, all of them lying in the fame plane like the branches of the common fern. The pancreatic duft is fometimes double in man, one lying above the other. It is not always of an equal length, and fometimes runs in a winding courfe, but always in the fame plane; and it is nearer the lower than the upper fide of the pancreas. It pierces the coats of the duodenum, and opens into the du&us cholidochus, commonly a little above the prominent point of the orifice of that canal; and fometimes it opens immediately into the duodenum. SPLEEN. The fpleen is a bluifli mafs, fomething inclined to red, and of a long oval figure, being about feven or eight fingers-breadth in length, and four or five in breadth. It is of a foftilh fubftanee, and is fituated in the left hypochondrium, between the great extremity of the ftomach, and the neighbouring falfe ribs, under the edge of the diaphragm, and above the left kidney. The inner or concave fide is divided by a longitudinal groove or feiflure, in two planes or half-fides, one upper, the other lower; and by this groove, the veflels and nerves enter in human fubjedts. The fuperior half-fide is broader and more concave than the inferior, being proportioned to the convexity of the great extremity of the ftomach. The inferior half-fide lies backward on the left kidney," and forward on the colon; and fometimes this fide of the fpleen appears to have two fuperficial cavities, one anfwering to the convexity of the ftomach, the other to that of the colon. The convex fide of the fpken is turned to the left ribs.

O M Y. Part VI. It is connedted to the ftomach, by the veflels called vafa brevia; to the extremity of the pancreas, by ramifications of the fplenic artery and vein; and to the omentum, by ramifications v/hich the fame artery and vein fend to the fpleen, and which run in the longitudinal groove. It is connedted to the edge of the diaphragm by a particular membranous ligament of different breadths in different fubjedts, fixed in its convex fide, fometimes near the upper edge, and fometimes near the lower. The ftrudture of the fpleen is not eafy to be unfolded in man, and it is very different from that of the fplecns of brutes, from which both public and private demonftratiorls are commonly made. Its coverings adhere to it fo clofely in man, that it is difficult to diftinguifh the common from the proper coat; whereas in fome brutes, fuch as oxen, fheep, <fac. we eafily find two coats feparated by a cellular fubftance^ This covering feems to be no otherwife a continuation of the peritoneum than by the intervention of the omentum and mefocolon. In man the fubftance of the fpleen is almoft wholly vafcular. In oxen the fubftance of the fpleen is chiefly reticular, and in fheep it is cellular. In oxen and flteep there are no venal ramifications, but inftead thereof only open finufes difpofed like branches, except a fmall portion of a venal trunk perforated on all fides, at the extremity of the fpleen. In the human fpleen we fee foraething like glandular corpufcles, as in thofe of other animals; and there are numerous venal ramifications through its whole extent. Between thefe ramifications we every where obferve an appearance of exuavafated blood, lying in a kind of filamentary tranfparent and very delicate fubftance expanded through the whole fpleen. This filamentary fubftance, having furrounded all the ramifications, terminates in almoft imperceptible cells which communicate with each other. OMENTUM & APPENDICES EPIPLOICAi. The omentum is a large, thin, and fine membranous bag, furrounded on all fides by numerous portions of fat, which accompany and even inveft die fame number of arteries and veins adhering, clofely to each other. The greateft part of it refembles a kind of flat purfe or a fportfman’s empty pouch, and is fpread more or lefs on all the fmall inteftines from the ftomach to the lower part of the regio umbiliealis. Sometimes it goes down to the lower part of the hypogaftrium, and fometimes does not reach beyond the regio epigaftrica. It is commonly plaited or folded in feveral places, efpecially between the bands of fat. It is divided into a fuperior and inferior, an anterior and pofterior, and a right and left portion. The fuperior portion is in a manner divided into two borders, one of which is fixed along the great curvature or convex fide of the arch of'the colon, and the other along the great curvature of the ftomach. The commiflure or union of thefe two borders on the right fide,, is fixed to the common ligament or adhefion of the duodenumcolon. and