The flexor digitorum longus muscle is located on the inner side of the leg by the tibia. There are two bones in the lower leg: the tibia and fibula. The tibia is located on the inner part of the leg and is the larger of the two bones; it may also be referred to as the shinbone.

This muscle is thin where it begins, but the size gradually increases as it descends to the end. The origin of the muscle begins at the tibia and extends to the sole of the foot through the ankle joint while splitting into four tendons, each of which connects to the second through the fifth toes. The flexor digitorum longus muscle is responsible for the movement and curling of the second, third, fourth and fifth toes. This muscle makes it possible for the toes to grip the surface of floors, which is important when it comes to maintaining postural balance on surfaces that are rough or uneven.