Anatomy of the pudendal nerve and its terminal branches: a cadaver study

BACKGROUND: This study documents the anatomy of the pudendal nerve, which has a major role in maintaining faecal continence. Unexpected faecal incontinence can develop following perineal surgery even when the anal sphincters are not damaged. In addition, injury to the pudendal nerve might be encountered during pelvic procedures such as a sacrospinous colpopexy. METHODS: An anatomical study on 28 cadavers was conducted to examine the course of the pudendal nerve and its branches in the perineum. RESULTS: In five of the 28 cadavers dissected (four male, one female), a nerve plexus was found within the ischiorectal fossa in close proximity to the anal sphincters. The plexus received contributions from interconnecting branches of the inferior rectal and perineal nerves to innervate the external anal sphincter. In 11 of the 28 cadavers (five female, six male) an additional nerve arose from the medial aspect of the pudendal nerve at the level of the sacrotuberous and sacrospinous ligaments. This nerve continued distally and gave several branches to the perineum and the levator ani muscle. CONCLUSION: A sound knowledge of the anatomical variations of the pudendal nerve and its branches is essential for all surgeons operating in the perineal region.