The sphincter urethrovaginalis is a female-specific striated muscle forming the most distal component of the external urethral sphincter complex. It encircles both the distal urethra and the anterior vaginal wall, distinguishing it from the compressor urethrae which encircles the urethra above the vagina. Together with the compressor urethrae and rhabdosphincter, it forms the striated urethral sphincter complex.
| Origin | Perineal body and central tendon of the perineum |
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| Insertion | Encircles the distal urethra and the vaginal wall, blending with the circular vaginal smooth muscle |
| Nerve Supply | Pudendal nerve (S2-S4) via its perineal branch |
| Blood Supply | Internal pudendal artery |
| Actions | Compresses the distal urethra and the vaginal introitus; Contributes to voluntary urethral closure, particularly at the distal urethral level |
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The sphincter urethrovaginalis contributes to voluntary urethral closure and to the pressure response during pelvic floor contraction. Electromyographic assessment of the striated urethral sphincter records from this muscle during urodynamic studies. Obstetric trauma, particularly forceps delivery, can denervate or directly lacerate this sphincter, contributing to post-partum stress incontinence. Pelvic floor rehabilitation specifically targets this muscle alongside the compressor urethrae and rhabdosphincter.
Not externally palpable; assessed by urethral pressure profilometry and electromyography during urodynamic studies.
Pudendal nerve traction injury during prolonged second stage of labour or forceps delivery denervates the sphincter urethrovaginalis and other striated urethral sphincter components, producing post-partum stress incontinence that may improve spontaneously over months or require pelvic floor physiotherapy and surgical intervention for persistent cases.
