The ankle is a large joint made up of three bones:

The shin bone (tibia)

The thinner bone running next to the shin bone (fibula)

A foot bone that sits above the heel bone (talus)

The bony bumps (or protrusions) seen and felt on the ankle have their own names:

The medial malleolus, felt on the inside of your ankle is part of the tibia's base

The posterior malleolus, felt on the back of your ankle is also part of the tibia's base

The lateral malleolus, felt on the outside of your ankle is the low end of the fibula

The ankle joint allows up-and-down movement of the foot. The subtalar joint sits below the ankle joint, and allows side-to-side motion of the foot. Numerous ligaments (made of tough, moveable tissue) surround the true ankle and subtalar joints, binding the bones of the leg to each other and to those of the foot.