The pudendal nerve (S2–S4) provides sensory and motor innervation to the perineum. It leaves the pelvis and re-enters via which route?

• A Passes through the greater sciatic foramen below piriformis, winds around the ischial spine, and re-enters via the lesser sciatic foramen into the Alcock's canal ✓
• B Passes directly through the lesser sciatic foramen from the pelvis to the perineum
• C Exits through the obturator foramen and curves anteriorly to the perineum
• D Passes through the urogenital hiatus of the levator ani to reach the deep perineal pouch

Explanation

The pudendal nerve (S2-S4) exits the pelvic cavity via the greater sciatic foramen (below piriformis), briefly passes through the gluteal region lateral to the ischial spine and sacrospinous ligament, then re-enters the perineum via the lesser sciatic foramen to run in Alcock's canal (pudendal canal) — a fascial tunnel in the lateral wall of the ischiorectal fossa formed by the obturator fascia. Within this canal, it gives off the inferior rectal nerve, perineal nerve, and dorsal nerve of penis/clitoris. Pudendal nerve block is performed at the ischial spine.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.