Rectum
The rectum is the final section of the intestine that follows up the sigmoid colon at the height of the 3d sacral vertebra. It has the typical intestinal wall structure (from inside to outside): Tunica mucosa, Tunica submucosa, Tunica muscularis propria, Tunica subserosa and serosa. The vertical mucosal folds of the rectum (anal columns) form an excretory duct (anal canal). The segment above with transversal folds (plicae transversales) is called rectal ampulla. The anal opening is surrounded directly by the internal and external sphincter muscles and is also connected to the levator ani muscle.
