This is an excerpt from Dynamic Alignment Through Imagery - 2nd Edition by Eric Franklin.
Transverse Tarsal Joint
The transverse tarsal joint (the midtarsal joint) is composed of the talonavicular and the calcaneocuboid articulations (figure 11.38). Together with the subtalar joint, the
transverse tarsal joint creates most of the supination and pronation action of the foot. The two joints can work together to create a large degree of supination and pronation or in opposition to each other, allowing the forefoot and hindfoot to twist in opposite directions.