Muscle · Thigh

Vastus lateralis

Musculus vastus lateralis

Vastus lateralis is the largest of the four quadriceps and forms the whole outer wall of the thigh, from high on the femur near the hip down to the outer edge of the kneecap. The iliotibial band runs over the top of it, which is why the outside of the thigh so often feels dense and ropey — there are two different tissues stacked there. Its pull on the kneecap is outwards, and it is the counterweight to vastus medialis on the inside: whatever happens to the balance between those two shows up in how the patella sits and moves. It is also the muscle that does most of the work driving you up out of a squat or a deep step.