Name
Pronunciation
(FLEK-sur dij-i-TOR-um LONG-gus)
Origin/Proximal Attachment
Posterior surface of tibia, medial to tibialis posterior from just below the solesl line to within 7 or 8 cm of the distal end of the bone
crural fascia (covering tibialis posterior)
Insertion/Distal Attachment
Plantar surface of bases of 2nd – 5th distal phalanges of the toes
Action/Relevance
Primarily flexes 2nd - 5th toes
Weakly plantar-flexes foot (in comparison to gastrocnemius & soleus)
Weakly adducts & inverts foot
Innervation
Tibial nerve (S2, 3)
Notes
lies medial to flexor hallucis longus
thin & pointed proximally, but gradually widens as it descends
ends in a tendon that extends along almost the whole of its posterior surface
gradually crosses tibialis posterior & passes behind the malleolus, where it shares a groove with tibialis posterior but is separated from it by a fibrous septum, each tendon in its own compartment lined by a synovial sheath
it then curves obliquely forwards and laterally, in contact with the medial side of the sustentaculum tali, passes deep to the flexor retinaculum, and enters the sole of the foot
here it crosses superficial to the tendon of flexor hallucis longus & receives a slip from it
it continues across the sole to form the whole of the long flexor tendon of the 5th toe & contribute to those of the 2nd, 3rd and 4th toes
it may also send a slip to the tendon of flexor hallucis longus