At which joint does inversion of foot occur?

The subtalar joint, also known as the talocalcaneal joint is the aiculation between the talus and the calcaneus. The primary joint surface is the posterior facet, with much smaller middle and anterior facets. The motion of this joint is inversion of approximately 30 degrees and eversion of approximately 10 degrees. The tibialis posterior causes inversion and the peroneus brevis eversion at the subtalar joint. Inversion occurs both actively and passively at the time of toe-off. Active control is achieved by the gastrocsoleus and posterior tibial muscles, and passive inversion occurs by the action of the plantar aponeurosis, the external rotation of the lower extremity, and the oblique metatarsal break.