The cecum, ascending colon, and right part of the transverse colon (midgut-derived structures) are supplied by the superior mesenteric artery via the ileocolic, right colic, and middle colic arteries (Fig. 13.8). The left half of the transverse colon, the descending and sigmoid colon, and most of the rectum (hindgut-derived structures) receive their blood supply from the inferior mesenteric artery through the left colic, sigmoid, and superior rectal arteries (Fig. 13.8). The rectum is supplied by the superior rectal branch of the inferior mesenteric artery. Middle rectal arteries arise from the internal iliac vessels and the inferior rectal arteries come from the internal pudendal vessels. Anastomoses exist between the superior and inferior mesenteric arteries. Major branches of the ileocolic, right colic, left colic, and sigmoid arteries anastomose, forming a series of arches. These joined arches form a single continuous artery, referred to as the marginal artery of Drummond. The vasa recta, which supply the length of the colon, derive from this marginal artery. It is fed by
branches of the superior mesenteric artery, the inferior mesenteric artery, and the hypogastric artery. The point of junction between superior mesenteric and inferior mesenteric arteries is known as the Griffith point. The junction between the inferior mesenteric artery and the hypogastric vessels is called the critical point of Sudeck. The colon is most vulnerable to ischemia at these two regions (1). In addition, the marginal artery is often small at the area of the splenic flexure, making this area particularly vulnerable to the consequences of reduced blood flow. There is a well-defined capillary network beneath the absorptive cells of the surface epithelium (Fig. 13.9).