Subtalar joint connects with talus
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.