The lateral head of the gastrocnemius muscle, together with the medial head, makes up the gastrocnemius muscle that forms part of the calf. It comes from two immovable ends (or heads) located on the femur, one on the side (lateral) and one toward the center (medial). The far end of this muscle joins the strong Achilles tendon, which descends to the heel and attaches to the calcaneus. The gastrocnemiusmycontentbreak is a powerful plantar flexor of the foot, that aids in pushing the body forward when a person walks or runs. It also works to flex the leg at the knee.