About the Fibula

There are four bones in the human leg. The femur makes up the upper leg and is also known as the thigh bone (and is the largest bone in the human body). The patella is a small floating bone, also known as the knee cap. The tibia is the largest bone of two in the lower leg, and the fibula is the smaller bone. It is located on the outside of the lower leg and runs from the knee to the ankle. This bone serves as a connection point for muscles and tendons that aid in movement.

Hamstring Attachment

The top outer portion of the fibula serves as attachment for the biceps muscle (also known as the hamstring) as well as two long ligaments that hold the knee in place.

Peroneus Attachment

The top two-thirds of the outside of the fibula serves as a connection point for the muscle known as the peroneus longus. The other end of this muscle is connected to the foot bones. When this muscle is flexed, it enables the foot to turn outward as well as upward. The bottom two-thirds of the outside of the fibula are the connection point for the lower leg muscle the peroneus brevis. This muscle is shorter than the peroneus longus but also connects to the ankle and is responsible for everting the foot and raising it upward.

Soleus Attachment

The back of the upper part of the fibula serves as a connection point for the calf muscle known as the soleus. This muscle is smaller than the large gastrocnemius and is located underneath it and farther down the leg. It connects to the heel bone and, when flexed, allows you to raise up on your toes.

Toe Extensors

The extensor digitatorum longus is the muscle that flexes all the toes except the large one. It also lifts the ankle upwards and everts the foot. While the end of this muscle is on the bones of your second through fifth toes, the origin of this muscle attaches to the top front of the fibula.
The middle of the front part of the fibula is the origin of the muscle the extensor hallicis longus. The other end of this muscle inserts on the bone near the big toe and is responsible for flexing this toe upward.

Ankle Inversion

The upper part of the fibula also serves as an attachment for the muscle tibialis posterior. This muscle is connected to many small bones within the foot and is responsible for flexing the ankle downward as well as inverting the ankle (turning it inward).

Toe Flexion

In the middle of the back of the fibula, the flexor hallicis longus attaches. This muscle runs all the way down to underneath the first toe and is responsible for flexing it downward and, to a lesser extent, inverting the foot.