What is the primary action of the gluteus medius and minimus?

• A. Abduction of the hip and pelvic stabilization
• B. Adduction
• C. Extension
• D. Flexion of the knee

Answer: (A)

The main function of the gluteus medius and minimus is to move the thigh outward from the body’s midline (hip abduction) and to keep the pelvis level when you’re weight-bearing, such as during walking. They attach along the outer ilium and insert on the greater trochanter, so their fibers pull the femur away from the midline. This action is crucial for a stable pelvis in the single-leg stance phase of gait; when these muscles weaken, the pelvis tends to drop on the opposite side (a classic sign during gait).

While parts of these muscles can assist with other movements (anterior fibers helping a bit with internal rotation and hip flexion, posterior fibers with external rotation and extension), their primary role is hip abduction and pelvic stabilization. They don’t primarily cause knee movement, hip adduction, or pure knee flexion, which is why those options aren’t correct.