Name
Pronunciation
(eks-TEN-sor dij-I-TOR-um LONG-gus)
Origin/Proximal Attachment
Upper ¾’s of anterior-medial surface of fibula
Adjacent anterior surface of interosseous membrane
middle & distal phalanxes of crural fascia
Lateral condyle of tibia
Anterior crural intermuscular septum
Septum between it & tibialis anterior
Insertion/Distal Attachment
Dorsal surface of bases of foot
(At the MTP joints the tendons to the 2nd, 3rd & 4th toes are each joined on the lateral side by a tendon of the extensor digitorum brevis)
Action/Relevance
Extends the lateral 4 toes
Weakly dorsiflexes & everts 2nd-5th toes (via 4 tendons & a fibrous expansion) synergistically with tibialis anterior & extensor Hallucis longus
Innervation
Deep peroneal nerve (L4, 5,S1)
Notes
Pennate muscle
In upper part of low leg the anterior tibial vessels & deep peroneal nerve lie between the muscle & tibialis anterior
At a lower level extensor Hallucis longus also comes between them
It becomes tendinous at about the same level as tibialis anterior
The tendon passes behind the superior extensor retinaculum & within a loop of the inferior retinaculum with peroneus tertius
Tendon divides into 4 slips