Glossary Term:

Title

sphincter

Phonetic

<b>sfink</b>-ter

Description

a ring-like muscle that can open and close to control the passage of substances in the body. The urethral sphincter squeezes the urethra shut and provides urinary control. There are 2 of these muscles in the anus to control stool (feces), called the external and internal anal sphincters. See also anus, urethra.