Its lower extremity inclines a little forward, so as to be on a plane anterior to that of the upper end; it projects below the tibia and forms the lateral part of the ankle joint.

The bone has the following components: The blood supply is important for planning free tissue transfer because the fibula is commonly used to reconstruct the mandible.

On the lateral side is a thick and rough prominence continued behind into a pointed eminence, the apex (styloid process), which projects upward from the posterior part of the head.

The body of the fibula presents four borders - the antero-lateral, the antero-medial, the postero-lateral, and the postero-medial; and four surfaces - anterior, posterior, medial, and lateral.

The antero-lateral border begins above in front of the head, runs vertically downward to a little below the middle of the bone, and then curving somewhat lateralward, bifurcates so as to embrace a triangular subcutaneous surface immediately above the lateral malleolus.

The antero-medial border, or interosseous crest, is situated close to the medial side of the preceding, and runs nearly parallel with it in the upper third of its extent, but diverges from it in the lower two-thirds.

The postero-medial border, sometimes called the oblique line, begins above at the medial side of the head, and ends by becoming continuous with the interosseous crest at the lower fourth of the bone.

It is broad, and often deeply grooved; it is directed lateralward in the upper two-thirds of its course, backward in the lower third, where it is continuous with the posterior border of the lateral malleolus.

It extends past the lower end of the tibia and forms the outer part of the ankle providing stability to this joint.

[7] The adjective peroneal referring to the fibula bone or its surrounding structures derives from περόνη : perónē, the Ancient Greek word for a clasp.

In some animals, the reduction of the fibula has proceeded even further than it has in humans, with the loss of the tarsal articulation, and, in extreme cases (such as the horse), partial fusion with the tibia.