Obturator Externus

Description

Anterior pelvis and lower lumbar spine are rendered with the paired hip bones, sacrum, and proximal femora framing the obturator foramina. Along the external surface of the obturator membrane and the surrounding pubis and ischium, the obturator externus arises and its fibers course inferolaterally, curving around the rim of the obturator foramen toward the posterior aspect of the hip. Deep to the femoral head and neck, the tendon would pass to the trochanteric fossa on the medial surface of the greater trochanter. A deep lateral rotator. Placement of obturator externus matters because it sits at the interface of pelvis and thigh, where small changes in hip position alter its line of pull and its relationship to the hip capsule. Surgeons encounter it as a deep landmark during anterior approaches to the hip (direct anterior, Smith-Petersen), where its tendon lies close to the posteroinferior capsule and can be a reference when assessing short external rotators during exposure. Clinically, it is also implicated in obturator externus tendinopathy or strain, an underrecognized source of deep groin pain in athletes that can mimic intra-articular pathology and may be correlated with pain on resisted external rotation with the hip flexed. Use this asset in pelvic and hip anatomy teaching for medical and allied health curricula, where learners need to connect the obturator foramen, acetabulum, and proximal femur to the deep rotator group. It also supports orthopedic and sports medicine publications discussing differential diagnosis of groin pain, as well as surgical education materials describing tissue planes and muscular landmarks around the anterior hip. Anatomical accuracy verified by SciePro's Medical Advisory Board.