Flexor Digitorum Longus Muscle(FDL) Anatomy

This muscle is present on the back of lower leg and as the name signifies, it helps to bend the four small toes of the foot.

Flexor: muscle that bends a body part

Digitorum: referring to the four small digits of the foot

Longus: this muscle is longer than the other flexor muscle of the toes, which is accordingly named Flexor digitorum brevis.

Location:

This muscle is located deep in the posterior compartment of lower leg. It originates from the tibia. Tibia is the larger of the two bones of lower leg, present on the inner side of the leg. This muscle starts from the inner side of the back of the tibia.

It descends on the back of the leg and near the ankle changes into a tendon (thick band of fibers that join the muscle to bone). This tendon passes behind the inner bump of the ankle, along with other tendons and goes under the foot.

In the sole of the foot, this tendon travels obliquely forward, crossing the tendon of the flexor hallucis longus (the muscle that bends the big toe) and then divides into four separate tendons.

Each of the four parts inserts into the lower surface of the bones of the corresponding toes. Each toe has three small bones called phalanges. The tendinous extensions of flexor hallucis digitorum attaches to the phalanges that are farthest from the body (under the nail part).

Blood Supply:

Posterior Tibial Vessels

Nerve Supply:

Tibial Nerve S2, S3

Movements:

As the muscle contracts the tendon pulls the undersurface of the toe bones, bending the four toes downwards.

Functions:

It helps in gripping with the toes and in maintaining the arch shape of the foot.