Nerve
Pudendal nerve
Main nerve of the perineum
High-yield
S2, S3, S4 keep the pelvic floor off the floor. Blocked at the ischial spine for obstetric analgesia.
Overview
The chief nerve of the perineum, supplying the external genitalia, perineal muscles, and the external anal and urethral sphincters.
Reference facts
- Roots
S2, S3, S4 (sacral plexus)
- Course
Exits the greater sciatic foramen below piriformis, hooks around the ischial spine, re-enters through the lesser sciatic foramen, and runs in the pudendal (Alcock's) canal
- Motor
External anal sphincter, external urethral sphincter, and perineal muscles
- Sensory
Perineum and external genitalia