Cuboid bone: The cuboid bone is the outer bone in the instep of the foot. It is called the cuboid bone because it is shaped like a cube.

The cuboid bone articulates posteriorly (it has a joint in back) with the calcaneus (the heel bone) and anteriorly (it has joints in front) with the 4th and 5th metatarsals (bones just behind the 4th and 5th toes).