Anatomy of the Colon

The large intestine extends from the ileocecal valve to the anus and has an average length of 1 meter. It is divided up into 6 regions - the cecum, ascending colon, transverse colon, descending colon, sigmoid colon and rectum. The hepatic flexure lies between the ascending and transverse colon, and the splenic flexure lies between the transverse and descending colon. The proximal colon up to the mid-transverse colon is supplied by the superior mesenteric artery, and the remainder of the colon and upper rectum is supplied by the inferior mesenteric artery. The lower rectum is supplied by branches of the internal iliac and internal pudendal arteries. Venous drainage follows the same distribution. The large intestine has important neural plexuses within the submucosa and muscularis propria. Unlike the small intestine, the mucosa of the large bowel is flat and punctuated by crypts or pits. The epithelium contains goblet cells, absorptive cells, Paneth cells, and endocrine cells.