Ankle Bones and Joints
The ankle is made up of two joints, the inferior talocrural joint and the subtalar joint.
The inferior tibiofibular joint is located between the large bone of the lower leg (tibia) and the smaller fibula, which then attach to the talus bone of the foot to form the talocrural joint. The talocrural joint is sometimes called the true ankle joint and is responsible for dorsiflexion and plantar flexion (up and down) movement of the foot. The joint between the tibia and talus bears the most of our body weight.
Beneath the talocrural joint is the subtalar joint. The subtalar joint is located between the talus bone and calcaneus or heel bone. This joint is responsible for ankle inversion (turning in) and eversion (turning out).
Running between the tibia and fibula is a fibrous membrane called the interosseous membrane. This membrane joins the tibia and fibula all the way up the lower leg, extending toward the knee. At the upper end, near the outside of the knee, is the superior tibiofibular joint.
Any restriction or dysfunction of these joints can produce symptoms in the ankle. The bony joint surfaces all have articular cartilage that covers the ends of the bones. The articular cartilage has a smooth and shiny surface, which allows the ends of the bones to slide freely over each other.