Wiktionary
n. (context muscle English) A paired central muscle of the lower lip, situated at the tip of the chin.
Wikipedia
The mentalis is a paired central muscle of the lower lip, situated at the tip of the chin. It originates from the mentum and inserts into the chin soft tissue. The primary effect of the mentalis contraction is the upward-inward movement of the soft tissue complex of the chin, which raises the central portion of the lips in turn. In the setting of lip incompetence (the upper and lower lips do not touch each other at rest), the mentalis muscle contraction can bring temporary but strained oral competence.
In conjunction with orbicularis contraction, the mentalis muscle allows the lips to "pout." Externally, mentalis contraction causes wrinkling of the chin skin, as used in expressions of doubt or displeasure. It is sometimes referred to as the "pouting muscle."
Geniospasm is a genetic movement disorder of the mentalis muscle.
Usage examples of "mentalis".
The mentalis, the corrugator, all those little muscles of the face, those are the first things you learn in art school anatomy.
If she pouted a little under this scientific inspection, he noted the slight twitch of the mentalis muscle at its point of origin in the incisive fossa.