Like other portions of the gut, the large bowel is innervated by the autonomic nervous system. Parasympathetic nerves stimulate colonic motor activity, whereas sympathetic nerves inhibit motility and decrease blood flow to the mucosa. The cecum and the ascending and transverse portions of the colon are innervated by the vagus nerve, and the descending and sigmoid regions are innervated by pelvic postganglionic parasympathetic nerves. Sympathetic nerves emerge from the superior mesenteric ganglion to innervate the proximal two thirds of the colon. The remainder is innervated by sympathetic fibers derived from the inferior mesenteric ganglion. Sympathetic fibers innervating the distal rectum and anus derive from the hypogastric ganglion.