The cuboid bone is one of the seven tarsal bones located on the lateral (outer) side of the foot. This bone is cube-shaped and connects the foot and the ankle. It also provides stability to the foot.
This multi-faceted bone is positioned between the fourth and fifth metatarsals, which lie behind the fourth and fifth (pinky) toes and the calcaneus (heel bone).
Each surface is distinct and serves a specific purpose:
- The rough dorsal (top) surface is attached to the ligaments — fibrous connective tissues that connect bones — in the foot.
- The plantar surface, located at the front of the foot, has a deep groove for the plantar ligament and the peroneus longus tendon.
- The lateral surface has a deep groove, called the peroneal sulcus.
- The posterior (back) surface is smooth and triangular so it can articulate with (form a joint with) the calcaneus' anterior (front) surface.
- The anterior surface is smaller and irregularly triangular, divided into two different surfaces in order to accommodate the tarsometatarsal joints.
- The medial (inner side) surface of the cuboid bone is four-sided and broad, with an oval surface that allows it to articulate with the third cuneiform and the navicular bone.
The cuboid helps provide for the stability of the foot and the movement of the toes, in addition to ensuring proper weight distribution and flexibility along the plantar fascia that runs along the sole of the foot.