Nerve to obturator internus

The nerve to obturator internus is a nerve that innervates the obturator internus and gemellus superior muscles.

Course
The nerve to obturator internus originates in the sacral plexus. It arises from the ventral divisions of the fifth lumbar and first and second sacral nerves.

It leaves the pelvis through the greater sciatic foramen below the piriformis muscle, and gives off the branch to the gemellus superior, which enters the upper part of the posterior surface of the muscle.

It then crosses the ischial spine, reënters the pelvis through the lesser sciatic foramen, and pierces the pelvic surface of the obturator internus.