• The fibula (also known as calf bone, latin: (os) fibula) is the smaller of the two leg bones located on the lateral side besides the tibia.

    A a long bone the fibula has three parts: a diaphysis or shaft, and two epiphyses or extremities: proximal and distal.

    The proximal epiphysis is the proximal or upper end of the fibula and it presents with the head of the fibula, which features an articular surface.

    The articular surface of the head of the fibula is the articular surface facing the tibia at the proximal end of the fibula.

    The diaphysis or shaft of the fibula has three surfaces (lateral, medial, posterior) and three margins (anterior, posterior, interosseous), and the posterior surface features the medial crest.

    The interosseous margin is a bony ridge located between the anterior margin and the medial crest of the fibula for attachment of a part of the interosseous membrane.

    The medial crest is a bony ridge on the posterior surface of the fibula at the border between the origins of the tibialis posterior and flexor hallucis longus muscles.

    The distal epiphysis of fibula is the lower end of the bone, which features the lateral malleolus with a malleolar articular surface and the lateral malleolar fossa.

    A malleolus refers to a bony prominence on each side of the human ankle. The lateral malleolus is the prominence on the outer side of the ankle, specifically, on the distal epiphysis of the fibula.

    The malleolar articular surface is the surface of the lateral malleolus facing the talus.

    The lateral malleolar fossa is a depression on the posteromedial aspect of the lateral malleolus for attachment of the posterior talofibular ligament.