The obturator externus is the deepest external hip rotator, inserting in the trochanteric fossa deep to the quadratus femoris. It wraps around the inferior femoral neck, passing through the obturator sulcus where it is protected from direct trauma by its deep position. In hip arthroscopy it is identified as the floor structure seen in the peripheral compartment below the zona orbicularis during complete capsular evaluation.
| Origin | External surface of the obturator membrane and surrounding pubic and ischial rami |
|---|---|
| Insertion | Trochanteric fossa of the femur — medial to the greater trochanter, deep to the quadratus femoris |
| Nerve Supply | Obturator nerve (L3, L4) — posterior branch |
| Blood Supply | Obturator artery |
| Actions | Hip external rotation; Hip adduction assistance |
|---|
The obturator externus is rarely clinically isolated but contributes to the external rotation power needed for athletic hip function. Obturator nerve palsy from pelvic fracture or obturator hernia produces loss of hip adduction and thigh sensory loss in the obturator distribution (medial thigh). The obturator nerve passes through the obturator canal in close proximity to the muscle origin.
The obturator externus is not palpable externally due to its deep position medial to the femoral neurovascular bundle.
Obturator externus compression of the obturator nerve in the obturator canal producing medial thigh sensory loss and hip adductor weakness.
