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Patient Education

Our Health Library information does not replace the advice of a doctor. Please be advised that this information is made available to assist our patients to learn more about their health. Our providers may not see and/or treat all topics found herein.

Rectum, Anus, and Anal Sphincter

The rectum is a muscular tube about 5 in. (12.7 cm) long that is at the end of the large intestine (colon). The rectum connects the colon to the anus, which is the opening where stool exits the body.

The internal and external anal sphincters are rings of muscle at the opening of the anus. The sphincters keep the anus closed as stool collects in the rectum. Eventually the pressure on the rectum wall causes the internal anal sphincter to relax. Conscious control over the external anal sphincter allows stool to pass out of the body through the anus.