Synonyms of mental protuberance include mental process and protuberantia mentalis. Mental in this sense derives from Latin mentum (chin), not mens (mind), source of the more common meaning of mental.
The concept of a mental protrusion is also referred to as a mental process or protuberantia mentalis. Interestingly, the term "mental" in this context stems from the Latin word for chin, rather than its more commonly understood meaning of mind.