The posterior talocalcaneal ligament is a part of the subtalar joint, also known as the talocalcaneal joint, which is one of two joints in the human ankle. The subtalar joint is formed by the talus and calcaneus bones and allows for side-to-side movement of the foot. It is classified as a plane joint, meaning that the connecting bone surfaces are nearly flat and result in a gliding motion. The primary function of a ligament in the body is usually to connect two structures, often bones. A secondary function is to restrict joint movement. Another function of some ligaments is to support internal organs. Ligaments are made of tough fibrous tissue that is somewhat pliant. The posterior talocalcaneal ligament is a short band that attaches the lateral tubercle of the talus to the upper and medial surface of the calcaneus. The fibers of this ligament radiate from their attachment site on the talus. The main function of this ligament is to stabilize the subtalar joint.