Origin The nerve to obturator internus is a branch of the
lumbosacral plexus. It arises from the
anterior divisions of (the
anterior rami of
Course and relations It emerges inferior to the
piriformis muscle and exits the pelvis through the
greater sciatic foramen. It travels round the base of the
ischial spine lateral to the internal pudendal artery and nerve, and - while doing so - issues a branch to the
gemellus superior, which enters the upper part of the posterior surface of the muscle. It then re-enters the pelvis through the
lesser sciatic foramen to innervate the
obturator internus muscle, piercing the pelvic surface of this muscle. ==See also==