Flexor Hallucis Longus, Posterior View

Description

Arising from the inferior two thirds of the posterior fibula and adjacent interosseous membrane, the flexor hallucis longus occupies the deep posterior compartment of the leg, lying lateral to tibialis posterior and posterior to the distal tibia. In a posterior view you would expect to see its muscle belly tucked deep to soleus, then narrowing into a tendon that passes posterior to the medial malleolus in the tarsal tunnel before coursing along the plantar aspect of the foot toward the distal phalanx of the hallux. The tendon typically crosses deep to the flexor digitorum longus at the knot of Henry in the midfoot, a consistent relationship used to orient plantar dissections. Deep anatomy, cleanly organized. Clinically, this posterior perspective helps clarify why flexor hallucis longus tenosynovitis presents with posteromedial ankle pain and pain on resisted great toe flexion, as the tendon glides through a confined fibro-osseous tunnel behind the medial malleolus under the flexor retinaculum. The illustration also supports surgical planning for posterior ankle endoscopy and for tendon transfer or release procedures, where recognizing the FHL’s position relative to the posterior tibial neurovascular bundle and to the subtalar joint line reduces the risk of iatrogenic injury. Dancers and runners often reveal the anatomy the hard way. Use this artwork in lower limb anatomy labs when teaching the deep posterior compartment, in sports medicine texts covering FHL tendinopathy and stenosing tenosynovitis, or in operative manuals illustrating posteromedial approaches to the ankle and hindfoot and the plantar course of the tendon to the great toe. Anatomical accuracy verified by SciePro's Medical Advisory Board.