Urethral Sphincter
From BME Encyclopedia
Revision as of 21:57, 4 April 2010 by Tokiohotel (Talk | contribs)
A sphincter is a ring of muscle that opens and closes. The urethral sphincter, surrounds the urethra. It holds the urethra closed to prevent the leaking of urine. When relaxed, urine can pass through the urethra uninhibited.