The peroneus longus is a muscle located in the lateral compartment of the lower leg. It originates from the upper part of the fibula and runs down the leg, eventually attaching to the base of the first metatarsal and the medial cuneiform bone in the foot. This muscle plays a crucial role in foot movement, particularly in eversion and plantarflexion. In addition to its primary functions, the peroneus longus helps support the arch of the foot. It works in conjunction with other muscles, such as the peroneus brevis, to stabilize the ankle during activities like walking and running. Proper functioning of this muscle is essential for maintaining balance and mobility.