. Quain's elements of anatomy . e, however, there existbesides small effaceable folds or ruga3, other permanent ones, which cannotbe obliterated, even Avhen the tube is forcibly distended. These perma-nent folds are the valvules conniventes, or valves of Kerkring(fig. 521). They are crescentic projections of the mucous membrane,placed transversely to the axis of the bowel, each of them reachingabout one-half or two-thirds of the distance round the interior of thetube, and they follow closely one upon another along the intestine. Thelargest are about 2\ inches long and ^ of an inch wide at the
. Quain's elements of anatomy . e, however, there existbesides small effaceable folds or ruga3, other permanent ones, which cannotbe obliterated, even Avhen the tube is forcibly distended. These perma-nent folds are the valvules conniventes, or valves of Kerkring(fig. 521). They are crescentic projections of the mucous membrane,placed transversely to the axis of the bowel, each of them reachingabout one-half or two-thirds of the distance round the interior of thetube, and they follow closely one upon another along the intestine. Thelargest are about 2\ inches long and ^ of an inch wide at the middleor broadest part. Large and small valvula3 conniventes are often found to alternate with eachother. Some of them are bifurcated at one end, and others terminate abruptly,appearing as if suddenly cut off. Each consists of a fold of the mucous mem-brane, that is, of two layers placed back to back, united together by thesubmucous areolar tissue. They contain no part of the circular or of the STEUCTUEE OF SMALL INTESTINE. 601. longitudinal mnscular coats. Being- extensions of the mucous membrane, theyserve to increase the absorbent surface to which the food is exi^osed. There are no valvulte conniventes quite at the commencement of theduodenum ; a short distance from the pylorus they begin to appear ; beyondthe point at which the bile and pancreatic juice are poured into the are very large, regularly crescentic in form and placed so near to each Fig. 522.—^^ section of THE IKIESTIKAL MUCOUS MEM-BRANE OP THE KABBIT (slightly altered from Frey). i^- Two villi are represented, inone of which the dilated lactealalone is sliown, in the other theblood-vessels and lacteal are bothseeu injected, tho lacteal v/hite,the blood-vessels dark : a, thelacteal vessels of the villi; a,horizontal lacteal, wJiich they join;6, capillary blood-vessels in one ofthe villi; c, small artery; d, vein;e, the epithelium covering thevilli ; g, tubular glands or cryptsof Lieberklih
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Keywords: ., boo, bookcentury1800, booksubjectanatomy, booksubjecthumananatomy
