The third slip of extensor digitorum brevis inserts into the third toe, lying between the second and fourth slips. It is smaller than the second slip but contributes meaningfully to third toe extension, particularly during toe-off phase of gait.
| Origin | Dorsal surface of the calcaneus, central portion of EDB origin |
|---|---|
| Insertion | Dorsal surface of the proximal phalanx of the third toe and lateral EDL tendon to the third toe |
| Nerve Supply | Deep peroneal nerve (L5, S1) |
| Blood Supply | Arcuate artery |
| Actions | Extends the third MTP joint; Assists dorsiflexion of the third toe |
|---|
The third EDB slip is at risk during the third web space neuroma excision approach, where the dorsal incision passes through the EDB territory. EMG studies of individual EDB slips help localise deep peroneal nerve branch lesions within the foot. Selective atrophy of the EDB slips indicates deep peroneal nerve injury distal to the ankle.
Palpated on the lateral dorsum of the foot between the second and fourth metatarsals during resisted third toe extension.
Selective EDB atrophy from deep peroneal nerve injury at the dorsal foot level, producing third (and adjacent) toe extensor weakness without anterior compartment involvement.
