Flexor Hallucis Longus

Joe Muscolino

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The flexor hallucis longus on the right side of the body. The flexor digitorum longus has been ghosted in.

The Flexor Hallucis Longus is located in the Deep Posterior Compartment of the (lower) leg. The muscles in the deep posterior compartment are:



  • Posterior fibula to the plantar surface of the distal phalanx of the big toe.
    • The flexor hallucis longus attaches proximally onto the distal 2/3 of the posterior fibula and the distal 2/3 of the interosseus membrane.



  • Flexes the big toe at the metatarsophalangeal and interphalangeal joints.
  • Plantarflexes the foot at the ankle joint.
  • Inverts (Supinates) the foot at the subtalar joint.



  1. The flexor hallucis longus is sometimes referred to as “Harry” of the “Tom, Dick, and Harry” group.
  2. Flexor hallucis longus is the largest of the three Tom, Dick, and Harry muscles.
  3. Inversion is the principal cardinal-plane (frontal-plane) component of the oblique-plane motion pattern of supination.