The peroneus brevis is one of the muscles of the lateral compartment of the leg. It originates from the lower two-thirds of the fibula on its lateral aspect. It lies deep to peroneus longus throughout its course inferiorly to the ankle.
The tendon of peroneus brevis passes posteriorly around the lateral malleolus in a common synovial sheath with peroneus longus. It then passes anteriorly and superior to the peroneal trochlea on the lateral surface of the calcaneus. Immediately beyond this, it inserts into the tubercle at the base of the fifth metatarsal.
Peroneus brevis is tethered down by two bands of deep fascia around the ankle: the superior and inferior peroneal retinacula.
Innervation is provided by the superficial peroneal nerve (L5, S1).
The actions of peroneus brevis are to plantarflex and evert the foot. Also, it acts to weakly support the lateral longitudinal arch.