Which muscle bends the knee?

The muscles that control the knees include the quadriceps, hamstrings and calf muscles. These muscles all work together to allow the knee to move freely in order to walk, run, kick and jump.

The quadriceps muscles that help control the knee include the vastus lateralis, vastus medialis, vastus intermedius and rectus femoris. These muscles begin in the ilium and attach to the tibia. Contraction of the quadriceps muscles allows the knee to extend. The hamstring muscle groups include the biceps femoris, semitendinosus, and the semimembranosus. These muscles are flexor muscles. In the calf, the gastrocnemius and the calcaneus muscles extend the posterior wall of the knee and act as flexor muscles.