sustentaculum
A supporting structure, a body part that supports one or more other parts.
The ligamentum talocalcaneum mediale lies obliquely on the medial side of the joint, and consists of fibres which extend from the medial posterior tubercle of the talus to the posterior roughened border of the sustentaculum tali.
Where it comes from
From Latin sustentaculum; compare sustentate. Attested since the eighteenth century.
Adapted from the Wiktionary entry sustentaculum (CC BY-SA 4.0).