The obturator internus (also known as internal obturator, internal obturator muscle, obturator internus muscle, latin: musculus obturatorius internus) is a muscle of the posterior muscle group of the pelvic girdle.
The obturator internus originates in the lesser pelvis from the internal surface of the obturator membrane.
The obturator internus exits the lesser pelvis via the lesser sciatic foramen and inserts on the trochanteric fossa of the femur.
The major function of the obturator internus is the external rotation of the femur. The obturator internus also helps to stabilize the hip joint.
The obturator internus is innervated by the muscular branches of the sacral plexus.