What Is a Urinary Sphincter?
The urinary sphincter, also referred to as the urethral sphincter, is a series of muscles that contract around the urethra in order to achieve bladder control. An internal urinary sphincter prevents flow of urine through the urinary tract from the bladder, and the external urinary sphincter provides additional voluntary control. Weakness or malfunction of these muscles can lead to urinary incontinence. Function and structure of the urinary sphincter differs in men and women because of a different anatomical structure and different requirements of the muscle. For example, the internal urinary sphincter in men helps prevent urine from mixing with seminal fluid during ejaculation. In women, the external urinary sphincter consists of three separate muscles, one of which also contracts the vagina. Muscles to manage urinary flow can be controlled in both men and women by contracting the pelvic floor muscles.
