The |peroneus longus| is a superficial muscle that runs along the upper part of the outside of the leg. It originates from the upper shaft of the |fibula| (lower leg bone), descends across the outer side of the calcaneum (heel bone), crosses the sole of the foot and is inserted in the outer side of the base of the metatarsal bone of the big toe. This muscle works with the |peroneus brevis| to extend the foot.