Origin:
       the margin of bone immediately around the medial side of the obturator foramen, from the rami of the pubis and the inferior ramus of the ischium;
 
Insertion: posterior aspect of the greater trochanter;
Action: External Rotation of femur at the hip; (see external rotators)
Synergists: Periformis, Gemellus Superior, Gemellus Inferior, Obturator Internus, Quadratus Femoris; 
Nerve Supply: Sacral plexus, L5, S1, S2; (See Innervation) 
    note: the nerve to the obturator externus travels thru the Greater Sciatic foramen
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Isolated obturator externus muscle abscess presenting as hip pain.

Primary obturator externus pyomyositis in a child presenting as hip pain: a case report