Quick Facts
Origin: External surface of obturator membrane and adjacent bones.
Insertion: Trochanteric fossa of femur.
Action: Laterally rotates thigh at hip joint.
Innervation: Posterior branch of obturator nerve (L3-L4).
Arterial Supply: Obturator and medial circumflex femoral arteries.
Related parts of the anatomy
Origin
The obturator externus muscle originates from the:
- external surface of obturator membrane;
- external aspect of the bony margin of the obturator foramen.
Insertion
The fibers of the obturator externus muscle travel posterolaterally and insert, via a narrow spiraling tendon, onto the lateral aspect of the trochanteric fossa of the femur.
Key Features & Anatomical Relations
The obturator externus muscle is found in the medial compartment of the thigh. It is a flat, convergent type of skeletal muscle.
The obturator externus muscle is located:
- anterior to the obturator foramen and the quadratus femoris muscle;
- posterior to the neck of the femur, the capsule of the hip joint, and the pectineus and adductor brevis muscles;
- inferior to the inferior gemellus muscle.
Actions & Testing
The obturator externus muscle is involved in multiple actions:
- laterally rotates the thigh at the hip joint;
- helps stabilize the hip joint (Sinnatamby, 2011).
The obturator externus muscle cannot be tested in isolation. Therefore, it is tested simultaneously with the piriformis and quadratus femoris muscles and the three muscles of the triceps coxae (i.e., superior and inferior gemelli and obturator internus muscles) by laterally rotating the thigh at the hip joint against resistance (Standring, 2016).
References
Sinnatamby, C. S. (2011) Last's Anatomy: Regional and Applied. ClinicalKey 2012: Churchill Livingstone/Elsevier.
Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice. Gray's Anatomy Series 41st edn.: Elsevier Limited.
