Anal Object Anatomy
The anus is the opening on the gastrointestinal tract, where the stool exits. The anus marks the transition from the lining of the gastrointestinal tract to the external skin. The anal canal is a tube, 1-2 inches long that leads to the anus.
The anal canal is surrounded by circular muscles, called sphincters, and blood vessels. The sphincters control defecation.
- Hellinger MD. Anal trauma and foreign bodies. Surg Clin North Am. 2002 Dec;82(6):1253-60.