quadriceps femoris /kwod″riseps/ [L, quattuor, four, caput, head, femur, thigh] , the large extensor muscle of the anterior thigh, composed of the rectus femoris, the vastus lateralis, the vastus medialis, and the vastus intermedius. The quadriceps forms a large dense mass covering the front and sides of the femur. Tendons of the four parts of the muscle unite at the distal part of the thigh, forming a single strong tendon that embeds the patella and inserts onto the tibial tuberosity. The muscle functions to extend at the knee and flex the thigh.
