Peroneus Tertius

Question 1

Where does the peroneus tertius muscle arise from and insert into?

Answer 1

The peroneus tertius arises from the lower third of the anterior surface of the fibula, the lower part of the interosseous membrane, and an intermuscular septum between it and the peroneus brevis muscle.

The tendon passes under the superior extensor retinaculum and inferior extensor retinaculum, in the same canal as the extensor digitorum longus, before inserting into the dorsal surface of the base of the metatarsal bone of the fifth digit.

Question 2

Which nerve innervates the peroneus tertius?

Answer 2

The peroneus tertius is innervated by the deep tibial nerve due to being in the anterior compartment (the other peroneal muscles are innervated by the superficial tibial nerve).

Question 3

Which movements does the peroneus tertius contribute to?

Answer 3

The peroneus tertius acts in weak dorsiflexion and eversion of the foot.