Summary Peroneus tertius Origin Arises with the extensor digitorum longus from the medial fibular shaft surface and the anterior intermuscular septum (between the extensor digitorum longus and the tibialis anterior) Insertion Dorsal surface of the base of the fifth metatarsal Action Works with the extensor digitorum longus to dorsiflex, evert and abduct the foot Innervation Deep peroneal nerve (L5, S1) Arterial supply Anterior tibial artery