The peroneus longus (also known as fibularis longus, fibularis longus muscle, peroneus longus muscle, latin: musculus peroneus longus) is a superficial muscle located in the lateral region of the lower leg.
The peroneus longus originates from the head and the upper two-thirds of the lateral surface of the fibula, and also from the intermuscular septa.
From its origin the peroneus longus passes downward behind the lateral malleolus and inserts onto the medial cuneiform and the first metatarsal bone.
The functions of the peroneus longus are flexion, abduction and pronation of the foot.
The peroneus longus is innervated by the superficial peroneal nerve, a branch of the common peroneal nerve.