Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
The internal anal sphincter is a ring of smooth muscle at the end of the rectum that helps control the passage of feces out of the body. It operates involuntarily, responding to pressure as part of the digestive process.
A type of muscle found in various organs, including the digestive tract, that contracts involuntarily under the control of the autonomic nervous system.
Feces: Waste matter remaining after food has been digested, which is expelled from the body through defecation