Fig. 5. Transverse tarsal joint, pronated at left, supinated at right. The joint axes are labeled as follows: AJ, ankle joint; ST, subtalar; CC, calcaneocuboid; TN, talonavicular. When the heel is placed on the ground in the supinated position, inversion in the subtalar joint restores the vertical orientation of the shank and rotates the head of the talus so as to lock the transverse tarsal joint.