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Perineal Nerve

nervus perinealis

The perineal nerve is the larger terminal branch of the pudendal nerve, arising in Alcock canal at the ischial level and passing into the perineum. It divides into superficial and deep branches: the superficial branches supply the skin of the perineum and the posterior scrotum/labia; the deep branches supply the external anal sphincter, the external urethral sphincter, the bulbospongiosus, ischiocavernosus, transverse perineal muscles, and the urethral mucosa.

Region: Pelvis & Hip

Clinical Relevance

Clinical Notes

The perineal nerve motor branches are responsible for external sphincter function and perineal muscle coordination during voiding, defaecation, and sexual function. Pudendal nerve injury from prolonged cycling (cyclist's neuropathy), childbirth, or Alcock canal entrapment primarily affects perineal nerve distribution, producing perineal pain, dyspareunia, and sphincter dysfunction. Pudendal nerve decompression in Alcock canal targets the perineal nerve territory specifically.

Pathology

Common Injuries & Conditions

Perineal Nerve Branch in Obstetric Injury

Prolonged second stage of labour stretches the pudendal and perineal nerves as the fetal head compresses them against the ischial spines, producing post-partum perineal numbness, levator ani weakness, and external sphincter dysfunction contributing to post-partum faecal incontinence.