Origin

•  Ventral branches of the ventral rami S2, S3, and S4.

Region

•  Enter the gluteal region through the inferomedial part of the greater sciatic foramina and cross the sacrospinous ligaments close to the ischial spines in both male and female.

Branches

•  Inferior rectal nerves.

•  Perineal nerves.

•  Dorsal nerves of the clitoris (female).

•  Dorsal nerves of the penis (male).

Supply

•  The pudendal nerves supply the skin and organs of the perineum.

•  For detailed nerve supply, please see inferior rectal nerves, perineal nerves, and dorsal nerves of the clitoris (female) or penis (male).


Pathology


Rectal resection 

•  Rectal resections for carcinoma now include a mesorectal excision to maximize the chance of locoregional control of the tumor.

•  In this procedure, the mesorectum is removed from the pelvic sidewall, exposing the vessels, nerves, and musculature of the ischiopubic region.

•  It is important to avoid injuring these structures to preserve sensorimotor innervation to pelvic and lower extremity structures.

Pudendal nerve block 

•  Pudendal nerve block is used by obstetricians for the relief pain in the lower genital tract during the second stage of labor.

•  The transvaginal approach is most commonly used using a guarded needle.

•  The index and middle fingers are inserted into the vagina and the ischial spine and sacrospinous ligament identified.

•  The vagina is punctured below and behind the ischial spine and the needle advanced about 10 mm through the ligament to lie next to the pudendal nerve, which runs above the sacrospinous ligament.

•  The pudendal artery and vein run parallel to the nerve and the needle should be aspirated prior to injection of the local anesthetic to avoid inadvertent intravascular injection.

•  The procedure is repeated for the nerve on the opposite of the pelvis.

Sciatica 

•  A number of nerves originate from the sacral plexus that are of clinical relevance.

•  The main nerve formed by the sacral plexus is the sciatic nerve; this is the largest nerve in the body and passes down the posterior aspect of the leg after leaving the pelvis.

•  Sciatica is a pain at varying points along the course of the sciatic nerve that is usually caused by some form of nerve compression.

•  It is particularly common during pregnancy when the ligaments and supporting tissues have a greater laxity.

•  Joints are less stable and move more easily giving an increased chance of nerve compression.

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