See it on the 3D body
The cuboid bone lit on the 3D leg and foot, as in the leg and foot quiz. Turn the body, peel the layers, tap any structure for its name.
Quick answer
- Latin name
- Os cuboideum
- Type
- Short bone (tarsal bone)
- Location
- Outer side of the midfoot, in front of the calcaneus and behind the fourth and fifth metatarsals
- Joints
- Calcaneocuboid joint with the calcaneus; cuneocuboid joint with the lateral cuneiform; sometimes a small joint with the navicular; tarsometatarsal joints with the fourth and fifth metatarsals
The cuboid is the tarsal bone on the outer side of the midfoot, set between the calcaneus behind and the bases of the fourth and fifth metatarsals in front. Roughly cube-shaped, it carries a deep groove on its underside that guides the tendon of the fibularis longus across the sole.
Where it is and what it touches
The foot has two columns of bones. The inner column runs from the talus through the navicular and the three cuneiforms to the first three toes. The outer column is shorter and lower: the calcaneus, the cuboid, and the fourth and fifth metatarsals. The cuboid is the middle link of this outer column.
- Behind, it meets the front of the calcaneus.
- In front, it has two facets, one for the base of the fourth metatarsal and one for the base of the fifth.
- On its inner side, it meets the lateral cuneiform, and in some people it also touches the navicular.
- On its outer side, its edge is short and notched where the fibularis longus tendon turns under the foot.
The cuboid and the calcaneus lie low, close to the ground. This makes the outer side of the foot flatter than the inner side, where the arch is high. The bones of the foot page places it among all the tarsals.
Parts and landmarks
The name means cube-like, but the bone is closer to a wedge: thicker on its inner side than on its outer side.
- Posterior surface: a curved, saddle-like joint surface for the calcaneus. Its shape helps keep the outer column stable.
- Anterior surface: divided by a faint ridge into two facets for the fourth and fifth metatarsals.
- Medial surface: an oval facet for the lateral cuneiform, and sometimes a small one for the navicular.
- Plantar surface: crossed by a ridge, the tuberosity of the cuboid, with a groove in front of it. The tendon of the fibularis longus runs in this groove, from the outer edge of the foot toward the first metatarsal.
A small sesamoid bone sometimes sits inside the fibularis longus tendon where it turns around the cuboid.
Joints
- Calcaneocuboid joint: between the calcaneus and the cuboid. With the talonavicular joint beside it, it forms the transverse tarsal joint, a line across the foot where the front of the foot twists on the back of the foot. This helps turn the sole inward and outward.
- Cuneocuboid joint: a small gliding joint with the lateral cuneiform.
- Tarsometatarsal joints: with the fourth and fifth metatarsals. These are the most mobile of the tarsometatarsal joints, which lets the outer edge of the foot adapt to the ground.
Muscles and ligaments attached
No large tendon inserts on the cuboid. The fibularis longus only uses it as a pulley: its tendon bends around the bone and changes direction on its way to the medial cuneiform and first metatarsal.
- The fibularis longus slides in the groove on the underside.
- The flexor hallucis brevis starts in part on the underside of the cuboid and the lateral cuneiform.
- A small slip of the tibialis posterior often reaches it.
- The long plantar ligament, from the underside of the calcaneus, attaches to the ridge of the cuboid and continues to the bases of the metatarsals. It forms a roof over the fibularis longus tendon and supports the outer arch.
How to remember it
- The cube on the outside. Cuboid, cube, on the little-toe side.
- Four and five sit on the cube. The cuboid holds the bases of the fourth and fifth metatarsals.
- Pulley, not anchor. The fibularis longus turns around the cuboid without inserting on it.
In Anatomy Atlas 3D
In the app the bone is called "Cuboid bone". Turn the foot sole-up, show the leg muscles and follow the fibularis longus tendon into the groove of the cuboid. Test yourself in the leg and foot quiz. Anatomy Atlas 3D is free on iPad and iPhone.
Frequently asked questions
Where is the cuboid bone?
On the outer side of the midfoot, in front of the calcaneus and behind the fourth and fifth metatarsals.
Which bones does the cuboid articulate with?
The calcaneus, the lateral cuneiform, the fourth and fifth metatarsals, and sometimes the navicular.
What runs in the groove of the cuboid?
The tendon of the fibularis longus, on its way across the sole to the first metatarsal and medial cuneiform.
Do any muscles attach to the cuboid?
No large muscle inserts on it. Part of the flexor hallucis brevis starts on its underside, and a slip of the tibialis posterior often reaches it.
