Which muscle contributes to lateral stability during the stance phase?

Which muscle contributes to lateral stability during the stance phase?

• A. Gluteus medius
• B. Tensor fascia lata
• C. Vastus lateralis
• D. Rectus abdominis

Answer: (A)

Keeping the pelvis level during the stance phase of gait relies on the hip abductors, especially the gluteus medius. As you stand on one leg, the gluteus medius on that side contracts to abduct the thigh and prevents the opposite side of the pelvis from dropping. This lateral stabilization allows a smooth, stable gait. If this muscle is weak, the pelvis tends to drop on the opposite side, which you may recognize as a Trendelenburg pattern. The tensor fascia lata can assist with hip abduction and adds some stability through the iliotibial tract, but the primary muscle responsible for maintaining lateral stability during stance is the gluteus medius. The vastus lateralis is a knee extensor and does not control pelvic tilt in the coronal plane, and the rectus abdominis is involved in trunk flexion rather than frontal-plane stability of the pelvis.

Keeping the pelvis level during the stance phase of gait relies on the hip abductors, especially the gluteus medius. As you stand on one leg, the gluteus medius on that side contracts to abduct the thigh and prevents the opposite side of the pelvis from dropping. This lateral stabilization allows a smooth, stable gait. If this muscle is weak, the pelvis tends to drop on the opposite side, which you may recognize as a Trendelenburg pattern.

The tensor fascia lata can assist with hip abduction and adds some stability through the iliotibial tract, but the primary muscle responsible for maintaining lateral stability during stance is the gluteus medius. The vastus lateralis is a knee extensor and does not control pelvic tilt in the coronal plane, and the rectus abdominis is involved in trunk flexion rather than frontal-plane stability of the pelvis.