The quads, or quadriceps, are a group of four muscles: the rectus femoris, vastus lateralis, vastus medialis and the vastus intermedius. (What a mouthful!) These muscles are located at the front of your thigh and control movement of the knee.
They play a crucial role in walking, running, jumping, and squatting. One of the quad muscles, the rectus femoris, also plays a role in hip flexion. This helps swing your leg forward while walking and running. Finally, the vastus medialis also plays a role in stabilising the patella and knee joint.