The fibularis tertius is a muscle in the anterior compartment of the leg. It is an extension of the distal part of the extensor digitorum longus muscle and is not always present.
- Attachments: Originates with the extensor digitorum longus from the medial surface of the fibula. Its tendon descends onto the dorsal surface of the foot and attaches to the fifth metatarsal.
- Actions: Eversion and dorsiflexion of the foot.
- Innervation: Deep fibular nerve.
- Blood supply: Anterior tibial artery