Pudendal Nerve (PN)
What is the "Pudendal Nerve" ?


The pudendal nerve is a somatic nerve in the pelvic region which is a large branch of the sacral plexus (L4-5, S1-4) that innervates the external genitalia of both sexes, as well as sphincters for the bladder and the rectum. It originates in Onuf's nucleus in the sacral region of the spinal cord.

The pudendal nerve originates in the sacral plexus; it derives its fibers from the ventral rami of the second, third, and fourth sacral nerves (S2, S3, S4).

It passes between the piriformis and coccygeus muscles and leaves the pelvis through the lower part of the greater sciatic foramen. It crosses the spine of the ischium, and reenters the pelvis through the lesser sciatic foramen. It accompanies the internal pudendal vessels upward and forward along the lateral wall of the ischiorectal fossa, being contained in a sheath of the obturator fascia termed the pudendal canal (Picture-1). The pudendal nerve gives off the inferior rectal nerves. It soon divides into two terminal branches: the perineal nerve, and the dorsal nerve of the penis (males) or the dorsal nerve of the clitoris (in females).

Branch Description
Inferior anal nerves Given off shortly after passing through the Greater sciatic foramen.
Perineal nerve More superficial terminal branch
Dorsal nerve of penis
Dorsal nerve of clitoris
Deeper terminal branch, traveling into the deep perineal pouch
Posterior labial nerves Posterior labia
Picture - 1 : Schematic view of pudendal nerve anatomy
Physiology of PN:
The pudendal nerve innervates the penis and clitoris, bulbospongiosus and ischiocavernosus muscles, and areas around the scrotum, perineum, and anus. At sexual climax, the spasms in the bulbospongiosus and ischiocavernous results in ejaculation in the male and most of the feelings of orgasm in both sexes.