Fibularis longus muscle

The peroneusfibularis longus muscle (also known as fibularisperoneus longus muscle) is one of the muscles of the lateral compartment of the leg.

Summary

• origin: head of the fibula

• insertion: first metatarsal and medial cuneiform

• innervation: superficial peroneal nerve (superficial fibular nerve)

• action: foot eversion (and weak plantarflexion)

Gross anatomy

Origin

• from the head and upper two thirds of the peroneal aspect of the shaft of the fibula and intermuscular septum

Insertion​

• the peroneusfibularis longus tendon passes down the leg superficial to the peroneusfibularis brevis muscle and does not touch the lateral malleolus due to the intervening brevis tendon

• both peronealfibular tendons then course anteriorly toward the peronealfibular trochlea of the lateral calcaneum, at which point the longus tendon runs inferiorly to the peroneal trochlea

• from this point, the tendon passes into the plantar compartment of the foot and contacts the posterior ridge of the groove on the cuboid bone

• occasionally the fibrocartilaginous sesamoid, which lies within the longus tendon at this point, may ossify

• runs deep to the long plantar ligament 

• finally, the peroneus longus tendon runs anteromedially across the sole and inserts into the fibular aspect of the base of the first metatarsal and the adjacent aspect of the medial cuneiform bone

Arterial supply 

• fibular artery

Venous drainage

• vena comitantes and short saphenous vein

Innervation

• superficial peroneal nerve (L5, S1)

Action

• everts foot (in tandem with the peroneusfibularis brevis muscle)

• weak plantarflexion of the foot

• provides support for the lateral longitudinal arch and transverse arches

Antagonist

• tibialis anterior

Variant anatomy

• duplex belly fibularis longus 

• fusion of fibularis brevis and fibularis longus

• os peroneum