The pudendal nerve (S2, S3, S4) exits the pelvis through the greater sciatic foramen, winds around the ischial spine, and re-enters through the lesser sciatic foramen to reach Alcock's canal. In which fascial canal does the pudendal nerve travel in the perineum?

• A Perineal membrane — between the superficial and deep perineal pouches
• B Urogenital diaphragm — between the superior and inferior fasciae
• C Perineal body at the centre of the perineum
• D Pudendal (Alcock's) canal — a split in the obturator internus fascia on the lateral wall of the ischioanal fossa ✓

Explanation

Alcock's canal (pudendal canal) is a fascial tunnel formed by a splitting of the obturator internus fascia on the lateral wall of the ischioanal (ischiorectal) fossa. The pudendal nerve travels here alongside the internal pudendal artery and vein. Within the canal, the nerve divides into: inferior rectal nerve (external anal sphincter and perianal skin), perineal nerve (superficial and deep perineal muscles, scrotum/labium), and dorsal nerve of the penis/clitoris. Pudendal nerve block is performed by infiltrating anaesthetic near the ischial spine. This is an important site for pudendal neuralgia.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.