The blood supply of the colon includes arteries which deliver blood rich in oxygen and other nutrients to the bowel tissues and veins which return deoxygenated (oxygen poor) blood to the lungs and heart. Surgical decisions regarding resection of colon cancers are heavily dependent on the anatomic location in the colon and on the blood supply to that particular segment. The chief arterial sources are the superior mesenteric artery and the inferior mesenteric artery, which branch off the aorta, the very large artery that comes directly from the heart. The superior mesenteric artery through its branches provides blood to the small bowel, right colon and transverse colon. These branches are the ileocolic artery that supplies the cecum, appendix and final portion of the ileum; the right colic artery that supplies the right colon and the middle colic artery that feeds the transverse colon. The inferior mesenteric artery through the left colic artery branch feeds the left colon and through the sigmoidal arteries and the hemorrhoidal arteries supplies the rectum. Each artery has a complementary vein by the same name.