Human leg the femur. All four muscles unite in a common tendon inserted into the patella from where the patellar ligament extends it down to the tibial tuberosity. Fibers from the medial and lateral vasti form two retinacula that stretch past the patella on either sides down to the condyles of the tibia. The quadriceps is "the" knee extensor, but the rectus femoris additionally flexes the hip joint, and articular muscle of the knee protects the articular capsule of the knee joint from being nipped during extension. The sartorius runs superficially and obliquely down on the anterior side of the thigh, from
Gastrocnemius muscle Gastrocnemius muscle The gastrocnemius muscle (plural "gastrocnemii") is a superficial two-headed muscle that is in the back part of the lower leg of humans. It runs from its two heads just above the knee to the heel, a two joint muscle. The muscle is named via Latin, from Greek "γαστήρ" ("gaster") "stomach" and "κνήμη" ("knḗmē") "leg"; meaning "stomach of leg" (referring to the bulging shape of the calf). The gastrocnemius is located with the soleus in the posterior (back) compartment of the leg. The lateral head originates from the lateral condyle of the femur, while the medial head originates from