The quadriceps are a group of four muscles located at the front and sides of the thighs. These muscles originate from the femur bone and run down to the patella or kneecap.
The names of these four muscles are the rectus femoris, vastus medialis, vastus lateralis, and vastus intermedialis. In the human body, the quadriceps are strong, bulky muscles. Their main function is to help with leg extension at the knee joint, which is very important for running, walking and preventing buckling knees when standing. In particular, the rectus femoris helps flex the leg at the hip joint to make the leg move forward.