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Rectum, anus, and anal sphincter

The rectum is a muscular tube about 5 in. 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 through the anal sphincter.

The anal sphincter is a ring of muscles at the opening of the anus. The sphincter keeps the anus closed as stool collects in the rectum. Eventually the pressure on the rectum wall causes the anal sphincter to relax, allowing stool to pass out of the body through the anus.

Author Ralph Poore
Editor Kathleen M. Ariss, MS
Associate Editor Pat Truman
Primary Medical Reviewer Kathleen Romito, MD
- Family Medicine
Specialist Medical Reviewer C. Dale Mercer, MD, FRCSC, FACS
- General Surgery
Last Updated June 16, 2006

WebMD Medical Reference from Healthwise

Last Updated: June 16, 2006
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