Flexor hallucis longus muscle

The flexor hallucis longus m. is located in the deep posterior compartment of the leg. Its tendon runs through the flexor retinaculum (a.k.a. tarsal tunnel), making it the "Harry" in the Tom, Dick and very nervous Harry acronym for tendons passing through the tunnel.

action: Flexes hallux, plantar flexes ankle

nerve: Tibial n.

origin: Fibula bone and interosseous membrane

insertion: Distal phalanx of hallux (big toe)