The anus has a rich blood supply from the network of veins that line the skin of the anus.

The anal canal is located next to the rectum and the anus is the opening at the end of the digestive tract which is the last part of the colon (large intestine) located in the gastrointestinal tract. There is a structure called the anorectal line which separates the anus from the rectum.

The anus is held closed by a circular group of muscles called external sphincter ani. These same muscles also form the wall of the anus. The surface of the anus is kept moist by glands which release fluid into it. The levator ani muscles are a plate-like band of muscles which surround the anus and form the floor of the pelvis. Nearby structures are attached to the anus by tough tissue called fascia which surrounds the anus.