External sphincter muscle of male urethra
The external sphincter muscle of 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.
| 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 | |
| Origin | Junction of the inferior rami of the pubis and ischium to the extent of 1.25 to 2 cm. |
| Insertion | Ischiopubic rami |
| Nerve | Somatic fibers from S2-S4 through pudendal nerve |
| Actions | Constricts urethra, maintains urinary continence |
| Identifiers | |
| Latin | musculus sphincter urethrae externus urethrae masculinae, musculus sphincter urethrae membranaceae |
| TA98 | A09.4.02.016M |
| TA2 | 2421 |
| FMA | 19733 |
| Anatomical terms of muscle | |
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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