External sphincter muscle of male urethra

Sphincter urethrae membranaceae muscle
The male urethra laid open on its anterior (upper) surface. (Region visible, but muscle not labeled.)
Coronal section of anterior part of pelvis, through the pubic arch. Seen from in front. (Region visible, but muscle not labeled.)
Details
OriginJunction of the inferior rami of the pubis and ischium to the extent of 1.25 to 2 cm.
InsertionIschiopubic rami
NerveSomatic fibers from S2-S4 through pudendal nerve
ActionsConstricts urethra, maintains urinary continence
Identifiers
Latinmusculus sphincter urethrae externus urethrae masculinae, musculus sphincter urethrae membranaceae
TA98A09.4.02.016M
TA22421
FMA19733
Anatomical terms of muscle

The external sphincter muscle of the male urethra, also sphincter urethrae membranaceae, sphincter urethrae externus, surrounds the whole length of the membranous urethra, and is enclosed in the fascia of the urogenital diaphragm.

Its external fibers arise from the junction of the inferior pubic ramus and ischium to the extent of 1.25 to 2 cm., and from the neighboring fascia.

They arch across the front of the urethra and bulbourethral glands, pass around the urethra, and behind it unite with the muscle of the opposite side, by means of a tendinous raphe.

Its innermost fibers form a continuous circular investment for the membranous urethra.


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