Subtalar joint

In human anatomy, the subtalar joint, also known as the talocalcaneal joint, is a joint of the foot. It occurs at the meeting point of the talus and the calcaneus. The joint allows inversion and eversion of the foot, but plays no role in dorsiflexion or plantarflexion of the foot.

The talus is oriented slightly obliquely on the anterior surface of the calcaneus. There are two points of articulation between the two bones: one anteriorly and one posteriorly.
 * At the anterior talocalcaneal articulation, a convex area of the talus fits on a concave surface of the calcaneus.
 * The posterior talocalcaneal articulation is formed by a concave surface of the talus and a convex surface of the calcaneus.

Ligaments and membranes
The main ligament of the joint is the interosseous talocalcaneal ligament, a thick, strong band of two partially joined fibers that bind the talus and calcaneus. It runs through the sinus tarsi, a canal between the articulations of the two bones.

There are four additional ligaments that form weaker connections between the talus and calcaneus.


 * The anterior talocalcaneal ligament (or anterior interosseous ligament) attaches at the neck of the talus on the front and lateral surfaces to the superior calcaneus.


 * The short band of the posterior talocalcaneal ligament extends from the lateral tubercle of the talus to the upper medial calcaneus.


 * The short, strong lateral talocalcaneal ligament connects from the lateral talus under the fibular facet to the lateral calcaneus, and runs parallel to the calcaneofibular ligament.
 * The medial talocalcaneal ligament extends from the medial tubercle of the talus to the sustentaculum tali on the medial surface of the calcaneus.

A synovial membrane lines the capsule of the joint, and the joint is wrapped in a capsule of short fibers that are continuous with the talocalconeonavicular and calcaneocuboid joints of the foot.