Obturator internus

The obturator internus (Latin: musculus obturatorius internus) is a triangular-shaped muscle located deep within the pelvis. It extends between the hip bone and the femur. The obturator internus is located inferior to the gluteal muscles, and it provides lateral (external) rotation of the thigh. Therefore, the obturator internus belongs to the deep gluteal and lateral rotator muscle groups. Together with the superior gemellus and inferior gemellus muscles, it forms a muscle complex known as the triceps coxae muscles.

Origin

The obturator internus muscle originates from the internal surface of the obturator membrane and the boundaries of the obturator foramen.

Insertion

The obturator internus inserts on the medial surface of the greater trochanter of the femur.

Action

The obturator internus muscle provides external (lateral) rotation of the thigh at the hip joint. Also, it helps to stabilize the hip joint.

Innervation

The obturator internus is innervated by the nerve to obturator internus (L5 - S2) that arises from the sacral plexus.

Blood supply

The obturator internus muscle receives arterial blood supply from the obturator and internal pudendal arteries. Both are branches of the internal iliac artery.