During a difficult vaginal delivery, a large episiotomy is made in the right posterolateral direction. Which nerve provides the primary sensory supply to the perineal skin and is blocked by pudendal nerve block to perform this procedure painlessly?

• A Ilioinguinal nerve (L1)
• B Genitofemoral nerve (L1, L2)
• C Pudendal nerve (S2, S3, S4) ✓
• D Posterior femoral cutaneous nerve (S1, S2, S3)

Explanation

The pudendal nerve (S2, S3, S4) provides the primary sensory and motor supply to the perineum. It exits the pelvis through the greater sciatic foramen, winds around the ischial spine (the anatomical landmark for pudendal nerve block), and re-enters via the lesser sciatic foramen into the pudendal (Alcock's) canal. It divides into the inferior rectal nerve, perineal nerve, and dorsal nerve of the clitoris/penis. Pudendal nerve block is administered transvaginally or transperineally at the ischial spine to anesthetize the posterior perineum for episiotomy, instrumental delivery, and perineal repair.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.