Anal sphincter anatomy:

The muscles in the anal sphincter are used in the process of defecation.
- Reviewed last on: 5/22/2008
- Scott M. Gilbert, MD, Department of Urology, Columbia-Presbyterian Medical Center, New York, NY. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.