The compressor urethrae is a female-specific striated muscle arising from the ischiopubic rami and crossing anteriorly to compress the distal urethra from both sides above the perineal membrane. It is part of the external urethral sphincter complex in women, distinct from the sphincter urethrovaginalis which surrounds both urethra and vagina, and from the rhabdosphincter proper which encircles the midurethra.
| Origin | Ischiopubic rami bilaterally |
|---|---|
| Insertion | Anterior midline of the distal urethra, meeting its contralateral counterpart to encircle the urethra above the perineal membrane |
| Nerve Supply | Pudendal nerve (S2-S4) via the perineal nerve |
| Blood Supply | Internal pudendal artery |
| Actions | Compresses the distal urethra from the sides; Contributes to voluntary urethral closure and the stress continence response |
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The compressor urethrae, rhabdosphincter, and sphincter urethrovaginalis together constitute the striated urethral sphincter complex, which collectively provides voluntary urethral closure and the reflex urethral pressure rise during stress events. Urodynamic studies and electromyography assess the function of these muscles collectively as the external urethral sphincter. Surgical urethral sling procedures work by mechanically augmenting what these muscles can no longer do following denervation or anatomical disruption.
Not directly palpable; assessed functionally by asking the patient to stop micturition mid-stream and by urodynamic electromyography.
Combined weakness of the compressor urethrae, sphincter urethrovaginalis, and rhabdosphincter from pudendal neuropathy or direct obstetric trauma produces intrinsic sphincter deficiency, a severe form of stress incontinence with low urethral closure pressure on urodynamics, treated by bulking agents, urethral sling, or artificial urinary sphincter.
