ankle is a complex mechanism. What we normally think of as the ankle
is actually made up of two joints: the subtalar joint, and the true
ankle joint. The true ankle joint is composed of 3 bones, seen above from a front,
or anterior, view: the tibia which forms the inside, or medial,
portion of the ankle; the fibula which forms the lateral, or outside
portion of the ankle; and the talus underneath. The true ankle
joint is responsible for up and down motion of the foot.
Beneath the true ankle
joint is the second part of the ankle, the subtalar joint, which consists
of the talus on top and calcaneus on the bottom. The subtalar
joint allows side to side motion of the foot.