nerve to obturator internus nerve to obturator internus the nerve to obturator internus, also known as the obturator internus nerve, is a nerve that innervates the obturator internus and gemellus superior muscles. nerve to obturator internusplan of sacral plexus and pudendal plexus (nerve to the obturator internus and gemellus superior labeled at lower left)nerves of the right leg seen from behind (nerve to the obturator internus labeled at upper left)detailsfromsacral plexusinnervatesobturator internus and gemellus superior musclesidentifierslatinnervus musculi obturatorii internita98a14.2.07.028ta26550fma78711anatomical terms of neuroanatomy structure the nerve to obturator internus originates in the lumbosacral 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, re-enters the pelvis through the lesser sciatic foramen, and pierces the pelvic surface of the obturator internus.