A manual of anatomy . cter. The interior of the anal canal shows, in its upper and middlethirds, a number (five to ten) of vertical folds called the columns of 308 THE ALIMENTARY TRACT Morgagni {columna rectales). Between these are little depressions(sinuses rectales) bounded below by crescentic folds called the analvalves. The anal orifice is the lower aperture of the alimentary orifice is irregular and is usually surrounded by hairs, sebaceousand modified sweat glands {glandulm circumanales). At the orificethe mucous membrane of the rectum passes into the skin withoutany sharp lin
A manual of anatomy . cter. The interior of the anal canal shows, in its upper and middlethirds, a number (five to ten) of vertical folds called the columns of 308 THE ALIMENTARY TRACT Morgagni {columna rectales). Between these are little depressions(sinuses rectales) bounded below by crescentic folds called the analvalves. The anal orifice is the lower aperture of the alimentary orifice is irregular and is usually surrounded by hairs, sebaceousand modified sweat glands {glandulm circumanales). At the orificethe mucous membrane of the rectum passes into the skin withoutany sharp line of demarcation. The blood-vessels that supply the large bowel are as follows:Cecum and appendix by the ileocecal artery (from the ileocolic branchof the superior mesenteric artery); the ascending colon by the rightcolic (from the superior mesenteric); the transverse colon by the mid-dle colic (from the superior mesenteric) and the left colic (from theinferior mesenteric); sigmoid colon by the sigmoid branches of the. Fig. 224.—Lower part of the rectum and the anal canal. C C, columns of Morgagni; VJ ana! valves. inferior mesenteric artery; the rectum by the superior hemorrhoidal(from the superior mesenteric), the middle hemorrhoidal (from theinternal iliac) and the inferior hemorrhoidal (from the internalpudic). The venous blood of the rectum passes in two directions. Thereare two venous plexuses in the rectum, internal and external. Theinternal hemorrhoidal plexus gives rise to the inferior hemorrhoidalveins that empty into the internal pudic vein which is a tributaryto the inferior vena cava through the internal and common iliacveins. The external hemorrhoidal plexus gives rise to the superiorhemorrhoidal vein that empties into the inferior mesenteric veinwhich is a tributary to the portal vein. The blood that is distrib-uted by the inferior mesenteric artery is returned by venous channelsthat correspond to the arterial branches; these ultimately form theinferior mesenter
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecthumananatomy, bookyea
