Anatomy, Bony Pelvis and Lower Limb, Gemelli Muscles

The superior and inferior gemellus muscles are a pair of small triangle-shaped muscles found among the posterior hip and gluteal musculature in the posterior proximal lower extremity, commonly referred to collectively as the gemelli muscles. The gemelli muscles are two of six short external rotator muscles in the gluteal region of the proximal thigh. The remaining external rotators include the piriformis, obturator internus, quadratus femoris, and obturator externus muscles. The superior and inferior gemelli join the obturator internus as a conjoined tendon, sometimes referred to as the triceps coxae. The gemelli muscles assist in external rotation of the thigh and have implications in sciatic nerve dysfunction known as deep gluteal space syndrome or gemelli-obturator syndrome. The gemelli muscles, in conjunction with the obturator internus, are important surgical landmarks in the Kocher-Langenbeck and posterior approach to the hip, as well as essential for identifying and protecting the medial circumflex femoral artery. The surgical approaches described are useful for surgical hip dislocations, total hip arthroplasty, hip hemiarthroplasty, loose body removal, treatment of posterior wall and column acetabular, and pelvic ring fractures.