Your Achilles tendon is a large band of tissue in the back of your ankle. It connects your calf muscles to your heel bone. The tendon helps you point your foot down, rise on your toes, and push off when you walk. You use it almost each time you move your leg. Repeated stress can make the tendon more prone to injury. It may become inflamed and develop small tears (tendonitis). A complete tear through the tendon is called an Achilles tendon rupture.