ANUS

plural Anuses, or Ani, terminal portion and opening of the digestive tract of vertebrates and many invertebrates. In humans it comprises the anal canal and opening, the end of the large intestine. Its function is to excrete fecal material from the body. Numerous blood vessels surround the anal canal and may be subject to enlargement and rupture; this condition, commonly called a hemorrhoid (q.v.), or pile, may cause pain, bleeding, and projection of the vessels from the anal opening. See also anal canal; rectum.