Which of the following is NOT an external rotator of the hip?

• A. Gluteus medius
• B. Piriformis
• C. Obturator internus
• D. Obturator externus

Answer: (A)

Hip external rotation is mainly performed by the deep lateral rotator group, whose job is to turn the thigh outward and help stabilize the hip joint. Gluteus medius sits on the side of the hip and its primary action is to abduct the thigh and stabilize the pelvis during gait. Its fibers can influence rotation depending on the hip position, but it is not a primary external rotator. The other muscles listed are classic external rotators that actively rotate the thigh laterally. So, the muscle not functioning as an external rotator in its primary role is the gluteus medius.