The |vastus lateralis| is the largest of the quadriceps muscles. The quadriceps muscle group consists of four muscles: the |rectus femoris|, the |vastus lateralis|, the |vastus intermedius|, and the |vastus medialis|. They form a large fleshy mass that covers the front and sides of the |femur| (upper leg bone) and work as the primary extensor of the knee. The |vastus lateralis| occupies the outside of the thigh and extends partially around to the front and back of the thigh. It extends the lower leg at the |knee joint| and is used when rising from a squatting position.
