The fibularis longus muscle (also known as peroneus longus muscle) is one of the muscles of the lateral compartment of the leg.
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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 fibularis longus tendon passes down the leg superficial to the fibularis brevis muscle and does not touch the lateral malleolus due to the intervening brevis tendon
both fibular tendons then course anteriorly toward the fibular 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
Venous drainage
vena comitantes and short saphenous vein
Innervation
superficial peroneal nerve (L5, S1)
Action
everts foot (in tandem with the fibularis brevis muscle)
weak plantarflexion of the foot
provides support for the lateral longitudinal arch and transverse arches
Antagonist
Variant anatomy
duplex belly fibularis longus
fusion of fibularis brevis and fibularis longus
Related pathology
fibularis longus tendinosis/tendinopathy
fibularis longus tenosynovitis
fibularis longus tendon instability
