Muscles of the lower leg, historical artwork. The skin and fascia (connective tissue) have been removed to expose the muscles (red) of the outer (right) and inner (left) leg. The largest muscle in the calf (gastrocnemius), is attached to the heel of the foot by the Achilles tendon. The tibia or shin bone is clearly seen at the front of the leg in the left hand figure. Published in The Muscles of the Human Body; in a series of plates with references and physiological comments by Jones Quain in 1836.