Ankle joint movement, illustration. Bones of the ankle joint, showing the alignment of the bones and the range of movement (black lines) of the joint. The ankle is where the lower leg bones (the tibia, thicker bone; and fibula) articulate with the talus bone in the foot. Also known as the talocrural joint, the ankle joint is the only mortise-and-tenon joint in the human body, allowing a range of different movements.