Muscles that Move the Leg

The muscles that move the legs are found in the anterior, medial, and posterior compartments of the thigh.

The quadriceps femoris is the most prominent anterior compartment muscle. It is comprised of the vastus lateralis, vastus medialis, vastus intermedius, and rectus femoris muscles. Its primary function is knee extension. 

The sartorius muscle is also present in the anterior compartment. It flexes the knee and causes lateral thigh rotation at the hip joint and is called the tailor's muscle, as it aids in cross-legged sitting.

The gracilis, a straplike muscle in the medial compartment, flexes the leg at the knee joint. Additionally, it adducts and medially rotates the thigh. 

The posterior compartment muscles cause flexion at the knee and extension at the hip.

The posterior compartment includes the three hamstring muscles — the biceps femoris, the semitendinosus, and the semimembranosus. A tear of these muscles, a pulled hamstring, is a common sports injury.

The popliteus is a small muscle located posteriorly at the knee joint that aids leg movement. It causes medial rotation of the tibia to unlock an extended knee during flexion.