The quadriceps femoris muscle is composed of four prevailing muscles located at the front of the thigh. These four muscle regions are the Rectus femoris, Vastus lateralis, Vastus medialis and finally the Vastus intermedius. The strongest muscle in the body, the quadriceps is responsible for the extension of the knee.
There are several leg exercise that successfully target the quads. The most effective of the bunch tend to be the leg press as well as the squat. One excellent isolation exercise is the leg extension.