The obturator externus passes posterior to the femoral neck to reach the trochanteric fossa, making it a deep posterior hip muscle despite its anterior origin. Its course around the femoral neck is important in posterior hip dislocation assessment.
| Origin | Outer surface of the obturator membrane and the surrounding bone — obturator foramen margins |
|---|---|
| Insertion | Trochanteric fossa — posterior surface of the femoral neck |
| Nerve Supply | Posterior division of the obturator nerve (L3, L4) |
| Blood Supply | Obturator artery |
| Actions | External rotation of the hip — deep lateral rotator; Stabilises the femoral head in the acetabulum |
|---|
Obturator externus is tensioned in posterior hip dislocation as the femoral head displaces posteriorly. In hip arthroscopy for femoroacetabular impingement, the obturator externus tendon may be seen from the peripheral compartment. Obturator nerve palsy (from obturator hernia or pelvic trauma) produces obturator externus weakness along with adductor weakness.
Tested by resisted external rotation with the hip in extension.
Obturator externus and short external rotator disruption accompanying posterior hip dislocation requiring assessment of the posterior soft tissue envelope during closed or open reduction.
