Fibularis longus muscle

In human anatomy, the fibularis longus (also known as peroneus longus) is a superficial muscle in the lateral compartment of the leg, and acts to evert and plantarflex the ankle.

The muscle, the longest and most superficial of the three peroneus muscles, is attached proximally to the head of the fibula and its 'belly' runs down most of this bone.

It becomes a tendon that goes posteriorly around the lateral malleolus of the ankle, then continues under the foot to attach to the medial cuneiform and first metatarsal.

It is innervated by the superficial peroneal nerve, which arises from the fifth lumbar and first sacral roots of the spinal cord.