Flexor hallucis longus

The flexor hallucis longus (Latin: musculus flexor hallucis longus) is a deep muscle belonging to the posterior compartment of the leg. It lies on the fibular side of the leg and stretches between the fibula and distal phalanx of the hallux. Besides the flexor hallucis longus, the deep posterior leg muscles also include the flexor digitorum longus, tibialis posterior and popliteus muscles.

Flexor hallucis longus
OriginInferior two-thirds of posterior surface of fibula, interosseous membrane of leg
InsertionBase of distal phalanx of hallux
ActionFlexion of hallux, foot plantarflexion
InnervationTibial nerve (S2 - S3)
Blood supply Branches of posterior tibial and peroneal (fibular) arteries

Origin

The flexor hallucis longus muscle originates from the lower two-thirds of the posterior surface of the fibula and interosseous membrane of the leg.

Insertion

The flexor hallucis longus inserts on the base of the distal phalanx of the hallux.

Action

The flexor hallucis longus muscle provides flexion of the hallux at the first metatarsophalangeal and interphalangeal jonts and foot plantarflexion at the talocrural (ankle) joint.

Innervation

The flexor hallucis longus is innervated by the tibial nerve (S2 - S3) - a branch of the sciatic nerve.

Blood supply

The flexor hallucis longus muscle receieves arterial blood supply from the branches of the posterior tibial and peroneal (fibular) arteries.