Name

# Flexor Digitorum Longus

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