Which muscles are prime movers for hip external rotation?

Which muscles are prime movers for hip external rotation?

• A. Obturator externus, Obturator internus, Piriformis, Superior gemellus, Inferior gemellus, & Quadratus femoris
• B. Gluteus medius and Gluteus minimus
• C. Tensor fasciae latae
• D. Sartorius

Answer: (A)

Hip external rotation is produced mainly by a group of six deep lateral rotator muscles that surround the hip. These muscles—obturator externus, obturator internus, piriformis, superior gemellus, inferior gemellus, and quadratus femoris—originate around the pelvic bones and insert near the femur’s greater trochanter. When the thigh is rotated outward, these muscles contract to pull the femur laterally, making them the primary external rotators, especially as the hip moves from neutral toward extension. The other muscles listed don’t serve as primary external rotators. The gluteus medius and gluteus minimus are mainly abductors and, depending on the fibers, can contribute to internal rotation rather than external rotation. The tensor fasciae latae tends to flex, abduct, and medially rotate rather than externally rotate. Sartorius can externally rotate the hip when the hip is flexed, but it is not a primary external rotator. So the six deep external rotators form the principal group responsible for hip external rotation.

Hip external rotation is produced mainly by a group of six deep lateral rotator muscles that surround the hip. These muscles—obturator externus, obturator internus, piriformis, superior gemellus, inferior gemellus, and quadratus femoris—originate around the pelvic bones and insert near the femur’s greater trochanter. When the thigh is rotated outward, these muscles contract to pull the femur laterally, making them the primary external rotators, especially as the hip moves from neutral toward extension.

The other muscles listed don’t serve as primary external rotators. The gluteus medius and gluteus minimus are mainly abductors and, depending on the fibers, can contribute to internal rotation rather than external rotation. The tensor fasciae latae tends to flex, abduct, and medially rotate rather than externally rotate. Sartorius can externally rotate the hip when the hip is flexed, but it is not a primary external rotator.

So the six deep external rotators form the principal group responsible for hip external rotation.