The extensor digitorum longus is a pennate muscle, situated at the lateral part of the front of the leg.

It arises from the lateral condyle of the tibia; from the upper three-quarters of the anterior surface of the body of the fibula; from the upper part of the interosseous membrane; from the deep surface of the fascia; and from the intermuscular septa between it and the tibialis anterior on the medial, and the peroneal muscles on the lateral side.

The muscle passes under the superior and inferior extensor retinaculum of foot in company with the fibularis tertius, and divides into four slips, which run forward on the dorsum of the foot, and are inserted into the second and third phalanges of the four lesser toes.

This muscle varies considerably in the modes of origin and the arrangement of its various tendons.

This article incorporates text in the public domain from page 481 of the 20th edition of Gray's Anatomy (1918)