Name
Pronunciation
(FLEK-sur HA-loo-sus LONG-gus)
Origin/Proximal Attachment
Distal two 3rd’s of posterior surface of fibula (except for lowest 2.5 cm or so)
Interosseous membrane
Crural fascia (which covers tibialis posterior)
Posterior crural intermuscular septum
Insertion/Distal Attachment
Plantar surface of base of distal phalanx of hallux (big toe)
Action/Relevance
Flexes big toe
Weakly plantar-flexes foot
Weakly adducts & inverts foot
Innervation
Tibial nerve (L5, S1, 2)
Notes
Its fibres run obliquely down to a tendon that occupies nearly the whole length of the posterior aspect of the muscle
the tendon grooves the posterior surface of the lower end of the tibia, posterior surface of the talus, followed by the inferior surface of the sustentaculum tali of the calcaneus
the grooves on the talus & calcaneus are converted by fibrous bands into a canal, lined by a synovial sheath
in the sole ofr the foot it crosses the flexor digitorum longus from the lateral to the medial side, curving obliquely superior to it (at the crossing point the long digital flexor receives a fibrous slip from the flexor hallucis longus tendon)
the tendon then crosses the lateral part of flexor hallucis brevis to reach the interval between the sesamoid bones under the head of the first metatarsal
It continues along the plantar aspect of the hallux, running in an osseo-aponeurotic tunnel to the attachment point