The ankle joint (talocrural joint) is composed of 3 bones. The central ankle bone is the talus, this is surrounded on either side by the tibia and the fibula.
On the inside of the ankle, the joint is maintained by a very strong ligament, the deltoid ligament, which helps resist rolling in of the ankle. On the outside of the ankle are the much weaker lateral ankle ligaments. One of these ligaments, the anterior talofibular ligament (ATFL) is the most commonly injured ligament in the body.
The rearfoot consists of the largest bone in the foot, the calcaneus, as well as the talus. The joint formed between the two is the subtalar joint which plays a significant role in foot function.
The forefoot consists of the five metatarsals, the fourteen toe bones (the phalanges) and two sesamoid bones located under the big toe joint.