The ankle joint is the connection of three bones: the talus or ankle bone, tibia or shinbone, and the fibula. Below the talus is the calcaneus or heelbone. These bones are held together by a series of ligaments and tendons. Ligaments providing for bone to bone connection, and tendons providing muscle to bone connection.
Most ankle movement is caused by the muscles in the lower leg, passing over the ankle, and connecting in the foot. These muscles include the peroneus longus and peroneus brevis passing on the outside the ankle, connecting to the foot. These muscles rotate the ankle and foot downward and outward. The gastrocnemius and soleus in the calf connect, via the achilles tendon, to the calcaneus bone. When contracted, they rotate the foot downward. The posterior tibialis muscle supports the arch of the foot, and rotates the foot inward. The anterior tibialis rotates the foot upward.