The colon or large intestine includes the cecum, ascending colon, transverse colon, descending colon, sigmoid colon and rectum. Arterial supply to the ascending and transverse colon arises from the superior mesenteric artery. On the left side, arterial blood supply to the descending colon, sigmoid colon, and the superior portion of the rectum arises from the inferior mesenteric artery. An anastomosis between the superior mesenteric and inferior mesenteric arteries is formed by the marginal artery of Drummond along the transverse colon. With the exception of the middle and interior portions of the rectum, venous drainage of the colon is to the portal vein.