The posterior tibial artery is the larger of the two branches from the popliteal artery. It descends beneath the calf muscle and divides into branches to supply blood to the skin, muscles, and other tissues of the lower leg along the way. Some of these join the nerve networks behind the knee and around the ankle. The largest branch of the posterior tibial artery is the peroneal artery, which travels down along the fibula (lower leg bone) and contributes to the nerve network around the ankle.