The internal obturator muscle or obturator internus muscle originates on the medial surface of the obturator membrane, the ischium near the membrane, and the rim of the pubis.
It exits the pelvic cavity through the lesser sciatic foramen.
The internal obturator is situated partly within the lesser pelvis, and partly at the back of the hip-joint.
It functions to help laterally rotate femur with hip extension and abduct femur with hip flexion, as well as to steady the femoral head in the acetabulum.
Structure
Origin
The internal obturator muscle arises from the inner surface of the antero-lateral wall of the pelvis. It surrounds the obturator foramen. It is attached to the inferior pubic ramus and ischium, and at the side to the inner surface of the hip bone below and behind the pelvic brim. The pudendal nerve passes on the lateral surface of the internal obturator muscle and the coccygeus muscle. The sciatic nerve passes superficial to the internal obturator muscle on the posterior surface.
Insertion
The tendon inserts on the greater trochanter of the proximal femur.
Additional images
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File:Obturator internus muscle.jpg|Obturator internus muscle
File:Slide10A.JPG|Obturator internus muscle
File:Braus 1921 251.png|"Triceps coxae"
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