Urethral sphincter muscle

The **urethral sphincter muscle** refers collectively to two distinct anatomical structures—the internal urethral sphincter (smooth, involuntary muscle at the bladder neck) and the external urethral sphincter (striated, voluntary muscle in the deep perineal pouch)[1][2][3][4]. These muscles work together to control the retention and release of urine via the urethra, with the internal sphincter chiefly providing passive continence and the external sphincter providing voluntary control[2][3][4]. The internal sphincter also prevents retrograde semen flow during ejaculation in males[2][4]. Dysfunction or trauma to these muscles can result in urinary incontinence or retention. The term "urethral sphincter muscle tissue" does not refer to a molecular target, but rather to a complex of anatomical muscle structures comprised of smooth and skeletal muscle fibers, and thus is not considered a therapeutic target in the typical pharmacological sense[1][2][3][4][5][6].

Other names

Sphincter urethraeinternal urethral sphincterexternal urethral sphincterEUSIUSrhabdosphincter (male)urogenital sphincter (female)