Overview

Fibularis brevis arises from the lower two-thirds of the lateral surface of the fibula, deep to fibularis longus. Its tendon runs in a groove directly behind the lateral malleolus (in front of the longus tendon), passes above the fibular trochlea of the calcaneus, and inserts on the tuberosity of the base of the 5th metatarsal. It is the strongest evertor of the foot and assists plantarflexion. It is supplied by the superficial fibular nerve.

Anatomy

Origin: Lower two-thirds of the lateral surface of the fibula.
Insertion: Tuberosity on the lateral side of the base of the 5th metatarsal.
Action: Eversion of the foot; plantarflexion of the ankle.
Innervation: Superficial fibular nerve.
Nerve roots: L5–S2
Arterial supply: Fibular artery.

Function

Everts the foot
Assists plantarflexion
Protects against inversion injury

Clinical significance

Avulsion fracture of the 5th metatarsal base

During an inversion injury, the fibularis brevis tendon (and the lateral band of the plantar aponeurosis) can avulse the tuberosity of the 5th metatarsal ("pseudo-Jones" fracture). This must be distinguished from the true Jones fracture at the metaphyseal–diaphyseal junction, which has a high risk of non-union.

Split fibularis brevis tear

A longitudinal tear of the tendon as it is compressed against the fibula behind the malleolus causes chronic lateral ankle pain and swelling.

Compiled from standard anatomy and physiology references — see the Muscular System sources. For education only; not medical advice.