The pudendal nerve block is performed by identifying the ischial spine transvaginally or via the perineum. The pudendal nerve enters the perineum via which foramen after passing through the lesser sciatic foramen?

• A Greater sciatic foramen
• B Alcock's canal (pudendal canal) within the obturator internus fascia ✓
• C Urogenital hiatus
• D Obturator foramen

Explanation

The pudendal nerve (S2–S4) exits the greater sciatic foramen, wraps around the sacrospinous ligament/ischial spine, re-enters the lesser sciatic foramen, and then travels in the pudendal canal (Alcock's canal) — a fascial tunnel within the obturator internus fascia in the lateral wall of the ischioanal fossa. It supplies the perineum, external sphincters, and genitalia. Pudendal nerve block is performed by infiltrating near the ischial spine to anaesthetise the entire perineum for obstetric procedures.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.