Pudendal nerve block is administered at which landmark because the pudendal nerve crosses behind which structure?

• A Sacrotuberous ligament; nerve blocked at the gluteal surface
• B Obturator internus; nerve blocked at the lesser sciatic notch
• C Sacrospinous ligament at its attachment to the ischial spine
• D Ischial spine; the nerve is blocked at the ischial spine ✓

Explanation

The pudendal nerve (S2-S4) exits the pelvis through the greater sciatic foramen, passes around the ischial spine (and the sacrospinous ligament), and re-enters the perineum via the lesser sciatic foramen into the pudendal (Alcock's) canal. The ischial spine is the landmark for transvaginal or transperineal pudendal nerve block, which provides anesthesia to the perineum, vulva, and lower vagina during episiotomy repair or instrumental delivery. The needle is directed to just posterior to the ischial spine under the mucosa of the lateral vaginal wall.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.