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Superficial Fibularis Tendon Crossover

tendo musculi fibularis longi (crossover)

The peroneus longus tendon crosses the plantar midfoot from lateral to medial in the groove beneath the cuboid, directed by the peroneal tubercle of the cuboid, before inserting on the medial cuneiform and first metatarsal base. This crossover produces first ray plantarflexion and medial arch stabilisation — distinct from the purely everting action of the peroneus brevis. Peroneus longus pathology at the cuboid groove is an often-missed cause of lateral midfoot pain.

Region: Foot & Ankle

Biomechanics

Function & Actions

The plantar crossover produces first ray plantarflexion and medial arch stabilisation — the unique functional contribution of the peroneus longus

Clinical Relevance

Clinical Notes

Peroneus longus tenosynovitis at the cuboid groove produces lateral and plantar midfoot pain during push-off and single-leg heel rise. Ultrasound demonstrates the tendon in the groove beneath the cuboid. The peroneus longus contribution to first ray stability means that its weakness causes first ray dorsiflexion and hindfoot valgus in the cavovarus foot — the Coleman block test assesses first ray flexibility.

Pathology

Common Injuries & Conditions

Peroneus Longus Cuboid Groove Pathology

Peroneus longus tenosynovitis at the plantar cuboid groove producing lateral midfoot pain during push-off managed with injection and load modification.