The extensor digitorum longus muscle is located at the front of the leg and is adjacent to the peroneus brevis muscle and the tibialis anterior muscle. This wing-shaped muscle works to extend the foot at the ankle, along with the four smallest toes.

The upper two-thirds to three-fourths of the muscle extends over the fibula and the muscle passes below the cruciate crural and transverse ligaments. After passing these ligaments, the muscle divides to provide motor function to the toes and is joined to the second, third, and fourth toe by tendons from the extensor digitorum brevis.

The deep peroneal nerve and the anterior tibial artery both serve this muscle.

Variations within the extensor digitorum longus muscle are not uncommon and include attachment to the big toe. Double tendons from the fifth or second toe (in a minority of cases) have also been observed without adverse effects.

Inflammation of this muscle will make climbing stairs difficult, but problems can be avoided by working a shin stretch into a regular fitness routine. Exercises such as toe raises can strengthen the muscle and prevent inflammation if recurring strains become problematic.