Flexor hallucis longus muscle

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The flexor hallucis longus muscle (FHL) is a muscle located on the posterior aspect of the leg. It is one of the deep muscles of the posterior compartment of the leg, and it plays a crucial role in the movement of the foot and toes, particularly the big toe.

Anatomy

The flexor hallucis longus muscle originates from the posterior surface of the fibula, specifically from the middle third of the bone. It also arises from the interosseous membrane and the posterior intermuscular septum. The muscle fibers converge into a tendon that travels down the leg, passing behind the medial malleolus of the tibia, and enters the sole of the foot.

The tendon of the FHL runs through a groove on the posterior surface of the talus and the sustentaculum tali of the calcaneus. It then crosses the sole of the foot to insert on the base of the distal phalanx of the great toe (hallux).

Innervation

The flexor hallucis longus muscle is innervated by the tibial nerve, which is a branch of the sciatic nerve. The tibial nerve provides the motor supply necessary for the muscle to perform its functions.

Blood Supply

The blood supply to the flexor hallucis longus muscle is primarily provided by the fibular artery, which is a branch of the posterior tibial artery.

Function

The primary function of the flexor hallucis longus muscle is to flex the joints of the big toe. This action is essential for activities such as walking, running, and jumping, as it helps in pushing off the ground. Additionally, the FHL assists in plantar flexion of the ankle joint, contributing to the stabilization of the foot during movement.

Clinical Significance

Injuries or conditions affecting the flexor hallucis longus muscle can lead to difficulties in toe flexion and impaired gait. Common issues include tendinitis, which is inflammation of the tendon, and "dancer's tendinitis," which is prevalent among ballet dancers due to repetitive stress on the tendon.

Also see

• Flexor digitorum longus muscle
• Tibialis posterior muscle
• Plantar flexion
• Tibial nerve
• Posterior compartment of the leg