Flexor hallucis longus muscle

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Flexor hallucis longus muscle
The mucous sheaths of the tendons around the ankle. Medial aspect. (Flexor hallucis longus visible at bottom center.)
Latin Musculus flexor hallucis longus
Gray's p.485
Origin fibula, posterior aspect of middle 1/3
Insertion Plantar surface; base of distal phalanx of hallux
Artery Peroneal artery (peroneal branch of the posterior tibial artery)
Nerve tibial nerve, S1 & S2 nerve roots
Actions flexes all joints of the big toe, plantar flexion of the ankle joint
Antagonist Extensor hallucis longus muscle
TA A04.7.02.053
FMA FMA:22593
Anatomical terms of muscle

The Flexor hallucis longus muscle (FHL) is a muscle of the leg. It is one of the deep muscles of the posterior compartment of the leg. The other deep muscles of the leg are flexor digitorum longus and tibialis posterior. Tibialis posterior is the most powerful of these deep muscles.


The Flexor hallucis longus is situated on the fibular side of the leg. It arises from the inferior two-thirds of the posterior surface of the body of the fibula, with the exception of 2.5 cm. at its lowest part; from the lower part of the interosseous membrane; from an intermuscular septum between it and the Peronæi, laterally, and from the fascia covering the Tibialis posterior, medially.

The fibers pass obliquely downward and backward, and end in a tendon which occupies nearly the whole length of the posterior surface of the muscle.

This tendon lies in a groove which crosses the posterior surface of the lower end of the tibia, the posterior surface of the talus, and the under surface of the sustentaculum tali of the calcaneus; in the sole of the foot it runs forward between the two heads of the Flexor hallucis brevis, and is inserted into the base of the last phalanx of the great toe. The grooves on the talus and calcaneus, which contain the tendon of the muscle, are converted by tendinous fibers into distinct canals, lined by a mucous sheath.

As the tendon passes forward in the sole of the foot, it is situated above, and crosses from the lateral to the medial side of the tendon of the Flexor digitorum longus, to which it is connected by a fibrous slip.


Usually a slip runs to the Flexor digitorum and frequently an additional slip runs from the Flexor digitorum to the Flexor hallucis. Peroneocalcaneus internus, rare,[clarification needed] arises below or outside the Flexor hallucis from the back of the fibula, passes over the sustentaculum tali with the Flexor hallucis and inserts into the calcaneum.

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This article incorporates text from a public domain edition of Gray's Anatomy.

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