Quick Facts
Origin: Anterior divisions of the anterior rami of fifth lumbar to second sacral nerves (L5—S2).
Course: Exits the pelvic cavity through the greater sciatic foramen. Winds around the ischial spine to enter perineum via the lesser sciatic foramen and comes to lie on the medial side of obturator internus.
Branches: None.
Supply: Motor innervation to obturator internus and gemellus superior muscles.
Related parts of the anatomy
Origin
The nerve to obturator internus (and the associated superior gemellus muscle) arises from the anterior divisions of the anterior rami of fifth lumbar to second sacral nerves (Aung et al., 2001).
Course
Following its origin from the lumbosacral plexus, the nerve leaves the pelvic cavity through the greater sciatic foramen inferior to the piriformis muscle. Like the pudendal nerve, it passes around the ischial spine and through the lesser sciatic foramen to enter the perineum.
Branches
There are no named branches.
Supplied Structures
The nerve to obturator internus muscle provides motor innervation to obturator internus and superior gemellus muscles.
References
Aung, H. H., Sakamoto, H., Akita, K. and Sato, T. (2001) 'Anatomical study of the obturator internus, gemelli and quadratus femoris muscles with special reference to their innervation', Anat Rec, 263(1), pp. 41-52.
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Obturator Internus Muscle
The obturator internus muscle is a large muscle on the interior of the pelvis arrayed in a series of parallel fingers or segments that all point toward the lesser sciatic notch from the interior of the pelvis.
