Which action is performed by the flexor hallucis longus?

Which action is performed by the flexor hallucis longus?

• A. Flexes first distal phalanx
• B. Plantarflexion
• C. Inversion
• D. Dorsiflexion

Answer: (A)

The action being tested is the ability of the flexor hallucis longus to bend the far end of the big toe. This muscle runs from the posterior leg, passes behind the medial malleolus, and inserts on the plantar surface of the distal phalanx of the hallux. When it contracts, it flexes the distal phalanx of the big toe (the tip), which is the key movement for gripping and pushing off during gait. This action is distinct from plantarflexion of the ankle, which involves the muscles that point the foot downward, or inversion, which is mainly produced by other muscles like tibialis posterior. Dorsiflexion, lifting the foot up, is primarily the job of the anterior compartment muscles. So, the most specific and primary action of the flexor hallucis longus is flexing the distal phalanx of the great toe.

The action being tested is the ability of the flexor hallucis longus to bend the far end of the big toe. This muscle runs from the posterior leg, passes behind the medial malleolus, and inserts on the plantar surface of the distal phalanx of the hallux. When it contracts, it flexes the distal phalanx of the big toe (the tip), which is the key movement for gripping and pushing off during gait.

This action is distinct from plantarflexion of the ankle, which involves the muscles that point the foot downward, or inversion, which is mainly produced by other muscles like tibialis posterior. Dorsiflexion, lifting the foot up, is primarily the job of the anterior compartment muscles. So, the most specific and primary action of the flexor hallucis longus is flexing the distal phalanx of the great toe.