Cuboid tunnel

The cuboid tunnel is an anatomical structure located on the plantar aspect of the lateral midfoot, formed by the groove on the plantar surface of the cuboid bone and the surrounding soft tissues. Its contents are the fibular (peroneus) longus tendon, which passes obliquely from the lateral to the medial side of the foot, and the associated synovial sheath and joint capsule.

The tunnel is bounded superiorly by the plantar groove of the cuboid, which is a distinct depression on the inferolateral aspect of the cuboid bone. Laterally and inferiorly, the tunnel is enclosed by the long plantar ligament and the fibrous sheath of the fibular longus tendon. The fibular longus tendon enters the tunnel after curving around the cuboid tuberosity, then courses medially toward its insertion at the base of the first metatarsal and medial cuneiform.

Within the tunnel, the fibular longus tendon articulates with an oval facet on the lateral tuberosity of the cuboid, which is covered by hyaline cartilage. The joint capsule of the peroneocuboid articulation is distinct and does not communicate with the tendon sheath. The synovial membrane is attached to the margins of the articular surfaces, peripheral to the cartilage region.

The position of the fibular longus tendon within the cuboid tunnel is dynamic, changing with ankle dorsiflexion and plantarflexion. In dorsiflexion, the tendon is perched plantar to the cuboid tuberosity, while in plantarflexion, it glides into the tunnel distal to the tuberosity.