Internal urethral sphincter

Definition

A urethral sphincter muscle which constricts the internal urethral orifice. It is the junction of the urethra with the urinary bladder. The muscle is made of smooth muscle, so therefore it is under involuntary control. It is kept tonically contracted by the sympathetic nervous system and during micturition, is relaxed via the parasympathetic nervous system. This is the primary muscle for preventing the release of urine[WP].

Also known as internal sphincter muscle of urethra, internal sphincter of urethra, internal urethral sphincter muscle, musculus sphincter supracollicularis, musculus sphincter urethrae internus, preprostatic sphincter, sphincter urethrae internus, supracollicular sphincter — per UBERON

The Internal urethral sphincter is a part of the Urinary.

Also identified as

• SCTID 277856008 per UBERON