Nerve
Pudendal nerve
Somatic nerve carrying perineal sensation and sphincter control
High-yield
The usual roots are S2–S4, but this does not make the pudendal nerve the sole supply of the pelvic floor. Levator ani also receives direct sacral branches, with pudendal contributions varying by muscle portion and study.
Overview
The pudendal nerve links sacral spinal segments with the perineum. Its branches serve external genital sensation, perineal muscles and the external anal and urethral sphincters, with overlapping contributions from neighboring nerves.
Reference facts
- Root value
- Usually S2–S4 ventral rami through the sacral plexus
- Course
- Leaves the greater sciatic foramen below piriformis, crosses behind the sacrospinous ligament near the ischial spine and enters through the lesser sciatic foramen; continues in a canal of obturator internus fascia
- Motor
- External anal and external urethral sphincters and several perineal muscles; contributions to levator ani are variable
- Sensory
- Much of the perineum, lower anal canal and external genitalia through inferior rectal, perineal and dorsal genital branches; anterior genital skin also receives other nerves
Clinical correlation
Its passage close to the ischial spine provides a landmark for clinician-administered pudendal anesthesia. This can reduce perineal pain during late childbirth or repair, but does not block pain from uterine contractions or cervical dilation.
Frequently asked questions
What are the roots of the pudendal nerve?
Usually S2–S4 ventral rami through the sacral plexus.
What muscles does the pudendal nerve supply?
External anal and external urethral sphincters and several perineal muscles; contributions to levator ani are variable.
What is the sensory distribution of the pudendal nerve?
Much of the perineum, lower anal canal and external genitalia through inferior rectal, perineal and dorsal genital branches; anterior genital skin also receives other nerves.
What is the course of the pudendal nerve?
Leaves the greater sciatic foramen below piriformis, crosses behind the sacrospinous ligament near the ischial spine and enters through the lesser sciatic foramen; continues in a canal of obturator internus fascia.