Tutorial 63 - The Pouting Muscle
The mentalis is so called because it was first attributed to an expression of thoughtfulness or doubt. You can see it in action when someone pauses for thought before speaking. The pouting expression, as seen on the illustration, also involves the mentalis.
The mentalis begins at the mandible (lower jaw) and inserts into the chin's tissue. When contracting, this soft tissue is bunched together and moves upwards, pushing the middle area of the lower lip up and out. Cute.