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Muscles/Lower Leg

Lower Leg

fibularis brevis

fih-byoo-LAIR-iss BREV-iss

The fibularis brevis, aka peroneus brevis, lies low on the outer lower leg and everts the foot while plantarflexing it. It's essential for lateral stability in running, surfing, or agility drills. Fitness athletes strengthen it to prevent ankle rolls.

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Common Pain & Injury

Lateral ankle/foot pain, swelling behind the outer ankle bone from twists or uneven terrain. Chronic tendinopathy common in runners. Doctor for instability or popping.

Anatomy & Function

Origin

Lower two-thirds of the lateral fibula (outer lower leg bone).

Insertion

Base of the fifth metatarsal (outer foot bone base).

Actions

  • Eversion of the foot (foot turn outward)
  • Plantarflexion (pointing foot down)

Innervation

Superficial peroneal nerve (L5-S1).

Muscle Relationships

Antagonists

Tibialis posterior

Synergists

Fibularis longusFibularis tertius

Trigger Points

Trigger points posterior to lateral malleolus refer pain to lateral foot and ankle.

Stretches

1Peroneal stretch with band
2Ankle inversion stretch

Common Conditions

Peroneus brevis tendinopathyPeroneal tendon subluxationFifth metatarsal stress fracture

Anatomical Parts

Right fibularis brevisLeft fibularis brevis

FAQ

Peroneus brevis pain?

Outer ankle pain from eversion sprains; rest, tape, strengthen.

Fibularis brevis function?

Everts foot for balance, prevents inward ankle rolls.

Peroneus brevis tear?

Sudden lateral foot pain, swelling; MRI for diagnosis.

Exercises for fibularis brevis

20

Also Works fibularis brevis

10

Related Lower Leg Muscles

extensor digitorum longus
The extensor digitorum longus runs lateral shin from knee to foot, extending toes 2-5 and dorsiflexing ankle. Builds shin definition for runners.
extensor hallucis longus
The extensor hallucis longus runs down the front of the lower leg and extends the big toe while also assisting in dorsiflexion of the ankle. It's crucial for clearing the foot during the swing phase of gait in runners and athletes. Strong EHL prevents foot drop and enhances explosive movements like jumping.
fibularis longus
The fibularis longus runs along the outer lower leg, crossing under the foot to evert and stabilize the arch. It powers push-off in sprinting and side-to-side movements. Crucial for runners to avoid ankle sprains and maintain foot alignment.
fibularis tertius
The fibularis tertius is a small muscle on the front-outer lower leg that assists in dorsiflexion and eversion. It's active in quick foot lifts during running or hiking. Often absent, but when present, aids ankle agility in sports.
flexor digitorum longus
The flexor digitorum longus is a powerful muscle in the deep posterior compartment of the lower leg, running from the tibia down to the toes. It flexes the four smaller toes and assists in plantarflexion at the ankle, helping with push-off during walking, running, and jumping. Strong flexors like this are crucial for balance, propulsion, and preventing foot drop in athletes.
flexor hallucis longus
Running deep in the calf's posterior compartment, the flexor hallucis longus flexes the big toe and plantarflexes the ankle. It's essential for powerful push-off in sprinting, ballet, and hill running. Athletes rely on it for toe grip on uneven terrain.
gastrocnemius
The gastrocnemius forms the visible calf bulge, crossing knee and ankle for explosive plantarflexion. Key for sprinting, jumping, and calf raises. Two heads make it powerful for athletic propulsion.
plantaris
The plantaris is a thin, vestigial calf muscle aiding knee flexion and plantarflexion, like a minor gas pedal muscle. Often ruptured without issue due to redundancy. Useful for explosive calf power in jumping.

Lower Leg Pain Guide

Common causes and relief

Activities & Sports

See which activities use fibularis brevis

Pinpoint·Interactive 3D Anatomy & Exercise Guide