Which type of muscle functions primarily to rotate the thigh?

The piriformis is a key muscle involved in the rotation of the thigh, primarily responsible for lateral rotation at the hip joint. Located in the gluteal region, the piriformis originates from the anterior surface of the sacrum and inserts into the greater trochanter of the femur. When the thigh is extended, the piriformis acts to externally rotate the limb, while it assists in abduction when the hip is flexed. This makes it crucial for movements that involve turning the leg outward, which is particularly important in various athletic activities and daily movements.

The quadriceps, primarily responsible for knee extension, do not contribute significantly to hip rotation. The gluteus medius plays a role in hip stabilization and abduction rather than rotation, and while the adductor muscles facilitate thigh movement toward the midline, they do not have a primary function in rotating the thigh. Understanding the specific roles of these muscles helps clarify why the piriformis is the correct choice for the rotation of the thigh.