Fibularis longus
Musculus fibularis longus
Also known as: peroneus longus, peroneal muscles
The superficial lateral-compartment muscle. Its tendon turns under the cuboid and crosses the sole to the 1st metatarsal and medial cuneiform. It everts and plantarflexes the foot and supports the transverse arch.
Overview
Fibularis longus arises from the head and upper two-thirds of the lateral surface of the fibula and the intermuscular septa. Its tendon descends behind the lateral malleolus (posterior to the fibularis brevis tendon), under the superior and inferior fibular retinacula, and passes below the fibular trochlea of the calcaneus. It then turns into a groove on the cuboid and crosses the sole obliquely to insert on the plantar surfaces of the base of the 1st metatarsal and the medial cuneiform. It inserts close to tibialis anterior, and the two form a "stirrup" under the midfoot.
It everts the foot and weakly plantarflexes the ankle. Its oblique course across the sole supports the lateral longitudinal and transverse arches and steadies the leg on the foot in single-leg stance. It is supplied by the superficial fibular nerve, which begins between it and the fibula. The common fibular nerve winds around the fibular neck deep to its upper fibres.
Anatomy
- Origin
Head and upper two-thirds of the lateral surface of the fibula.
- Insertion
Plantar surfaces of the base of the 1st metatarsal and the medial cuneiform.
- Action
Eversion of the foot and plantarflexion of the ankle; supports the arches.
- Innervation
Superficial fibular (peroneal) nerve.
- Nerve roots
L5–S2
- Arterial supply
Fibular artery and anterior tibial artery (branches through the intermuscular septa).
- Relations
The common fibular nerve passes between its attachment and the neck of the fibula. Its tendon lies behind brevis at the lateral malleolus.
Function
- Everts the foot
- Plantarflexes the ankle (weakly)
- Supports the transverse and lateral longitudinal arches
Clinical significance
Inversion ankle sprain
The fibularis muscles are the dynamic restraint against inversion. Delayed fibularis reaction time contributes to recurrent sprains of the lateral ligaments (anterior talofibular first), so proprioceptive training focuses on them.
Fibular tendon subluxation
Tearing of the superior fibular retinaculum, from forced dorsiflexion and eversion in skiing, lets the tendons snap over the lateral malleolus.
Compiled from standard anatomy and physiology references — see the Muscular System sources. For education only; not medical advice.