quadriceps

quadriceps 1 Any four-headed muscle. 2 The large muscle of the thigh that comes down the bone of the upper leg (femur) and over the kneecap (patella), and then anchors into the top of the large bone in the lower leg (tibia). The function of the quadriceps is to straighten (extend) the leg. Also known as musculus quadriceps femoris and quad.