Medial border of fibula

In the Terminologia Anatomica 2, the medial border of fibula denotes the bony crest which separates the fibular origin of the "M. tibialis anterior" from the origin of the "M. flexor hallucis longus" and therefore divides the posterior surface of the bone into two parts. [PNA, 1955] The term margo medialis appears more appropriate than crista medialis (previous term in TA1) as this feature appears between the medial and posterior surfaces of the fibula.

In other sources, the medial border of fibula is known as the interosseus border (a.k.a. the interosseus crest). It is located just medial to (or inside) the prominent anterior border. It ends below at a rough triangular area positioned above the articular facet (or talar facet) of the lateral malleolus. Several ligaments, such as the interosseus tibiofibular, anterior and posterior tibiofibular, and inferior transverse tibiofibular ligaments, connect this triangular area with the lower part of the tibia forming inferior tibiofibular joint. In its upper portion, the medial (or interosseus) border closely aligns with the anterior border, to the extent that they may appear indistinguishable from each other.

Kindly note that in the old four-border four-surface naming system for the fibula, the medial border is equivalent to the anteromedial border. For more information, please consult the specifics regarding the body of the fibula.