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Obturator Externus Muscle Anatomy

The Obturator Externus Muscle is a flat, relatively small, fan-shaped muscle that is deeply placed in the superomedial part of the thigh. It extends from the external surface of the obturator membrane and surrounding bone of the pelvis to the posterior aspect of the greater trochanter, passing directly under the acetabulum and neck of the femur.

The word obturator comes from the Latin word obturo, which means “to stop or block up.

It is one of the short external rotators of the hip joint that’s located in the outer side of lateral wall of pelvis. It’s one of the medial compartment’s muscles of the thigh that comprises the adductor group which contains the adductor longus, adductor brevis, adductor magnus, gracilis and obturator externus muscles.

See Also: Hip Muscles Anatomy

Obturator Externus Muscle lies deep in the proximal thigh, with its tendon passing inferior to the neck of the femur and deep to the quadratus femoris, on the way to its attachment to the trochanteric fossa of the femur. The obturator externus, with other short muscles around the hip joint, stabilizes the head of the femur in the acetabulum. It is most effective as a lateral rotator of the thigh when the hip joint is flexed.

Obturator Externus Muscle Anatomy

The Obturator Externus Muscle originates from the External surface of obturator membrane and anterior bony margins of obturator foramen. It passes inferior to the neck of the femur and deep to the quadratus femoris and inserts on the Trochanteric fossa on the medial surface of the greater trochanter.

It gets its innervation from the Posterior division of obturator nerve innervates most of the obturator externus (L3, L4), and gets its blood supply from the obturator and medial circumflex femoral arteries.

Its function is to rotates the femur laterally; it also helps adduct femur.

Obturator Externus Muscle Anatomy
OriginExternal surface of obturator membrane and anterior bony margins of obturator foramen
InsertionTrochanteric fossa on the medial surface of the greater trochanter
InnervationPosterior division of obturator nerve innervates most of the obturator externus (L3, L4)
Blood SupplyObturator and medial circumflex femoral arteries
ActionRotates the thigh laterally; also helps adduct thigh

References

  1. Gray’s Anatomy: The Anatomical Basis of Clinical Practice
  2. Clinically Oriented Anatomy – 8th Edition
  3. Larson MR, Ryan W. Anatomy, Abdomen and Pelvis, Obturator Muscles. [Updated 2023 Jan 17]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: Pubmed
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