Fibular

Usually, the tendons of the fibular muscles (except the one of the third fibular) have, against the lateral malleolus and on the lateral surface of the tarsus, a system of sheaths (sheaths of the fibular) totally distinct form the others.

The reinforced part of the fascia that contributes to the constitution of these sheaths is called retinaculum of the fibulars. The tendons slide inside it thanks to synovial vaginals, whose disposition varies a bit according to the species.