Fig. 2

Accessory muscle: peroneus quartus. Axial T1-WI at the level of the subtalar joint (a) and slightly below (b). Peroneus quartus (long arrow) positioned posteromedial to tendons of the long (short arrow) and short (arrowhead) peroneal muscle. Several types of peroneus quartus are described based on the distal insertion, which can be onto the peroneal tubercle or the retrotrochlear eminence of the calcaneus, and less frequently the cuboid, the peroneus longus or the inferior peroneal retinaculum