Obturator internus muscle is situated partly within the true pelvis and at the back of the hip joint.
The origin of the obturator internus muscle lies within the true pelvis. It arises from the pelvic surface of the obturator membrane and the adjoining part of hip bone.
From its origin, the muscle fibers converge into a tendon that passes through the lesser sciatic foramen. Outside the pelvis, the muscle passes posterior to the hip joint and reaches the greater trochanter of femur where it is inserted.
It is innervated by the nerve to obturator internus, a branch of the sacral plexus.
The primary blood supply to the muscle comes from superior gluteal artery, which is the largest branch of internal iliac artery.
The muscle laterally rotates the femur at the hip joint. It also assists in abducting the flexed thigh.