A ligament is a fibrous tissue that connects one bone to another. Ligaments are the primary source of stability for any joint and the ankle has many. The lateral ligaments around the outside of the ankle are sprained and often torn with an inversion injury. These ligaments include the anterior talofibular ligament (ATFL), calcaneofibular ligament (CFL), and the posterior talofibular ligament (PTFL). The lateral malleolus, which is the round bone protruding from the outside of your ankle, serves as the origin of these ligaments. The CFL begins here and then attaches to the calcaneus (heel bone). Both the ATFL and PTFL begin here as well but then attach to the talus (a bone in the center of the ankle).