The quadriceps is a group of four muscles that covers the femur anteriorly. The four named parts of the quadriceps are vastus lateralis, vastus intermedius, vastus medialis and the rectus femoris. These muscles arise from the proximal femur and ilium, and fuse together at the patellar tendon to insert upon the tibial tuberosity. The quadriceps contract to extend the knee and also participate in hip flexion.
In Our Own Words
The quads are the group of muscles that form the front fleshy part of the thigh (as opposed to the hamstrings in the back). They run from from the hip and the top part of the thighbone and come together at the knee joint, working through the patellar tendon to move your lower leg in all kinds of activities ranging from kicking to walking, and even getting up out of a chair. The four muscles of the quadriceps work together to straighten the leg and stabilize the knee. Quadriceps injuries, such as strains, are very common, especially those participating in sports.