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Muscles/Lower Leg

Lower Leg

flexor hallucis longus

FLEK-sor HAL-yoo-sis LON-gus

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.

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Common Pain & Injury

Calf or inner ankle pain radiating to the big toe, worse with toe-off. Tendinopathy from repetitive stress in dancers. Get checked if there's swelling, catching sensation, or inability to flex big toe.

Anatomy & Function

Origin

Posterior fibula and interosseous membrane (back of smaller leg bone)

Insertion

Distal phalanx of great toe (tip of big toe)

Actions

  • Interphalangeal joint flexion of hallux (curling big toe)
  • Plantarflexion (pointing foot down)
  • Foot inversion (turning inward)

Innervation

Tibial nerve

Muscle Relationships

Antagonists

Extensor hallucis longus

Synergists

Flexor digitorum longusTibialis posterior

Trigger Points

In calf muscle belly, referring to big toe, medial ankle, and sole of foot.

Stretches

1Lunge big toe stretch
2Calf stretch with big toe extended
3Kneeling big toe flexor stretch

Common Conditions

Flexor hallucis longus tendinopathyHallux rigidus

Anatomical Parts

Left flexor hallucis longusRight flexor hallucis longus

FAQ

What does flexor hallucis longus do?

Flexes big toe and points foot down for push-off power.

Flexor hallucis longus pain running

Tendinitis from overuse; strengthen calves and stretch deeply.

Flexor hallucis longus stretch

Extend big toe back in a deep calf lunge.

Flexor hallucis longus location

Deep calf to big toe tip.

Exercises for flexor hallucis longus

20

Also Works flexor hallucis longus

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 brevis
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.
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.
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 flexor hallucis longus

Pinpoint·Interactive 3D Anatomy & Exercise Guide