Which muscle can be raised to express surprise or lowered to show a stern gaze?

The frontalis muscle plays a key role in facial expression, particularly in raising the eyebrows. When this muscle contracts, it causes the skin on the forehead to wrinkle and the eyebrows to move upward, which is typically associated with the expression of surprise or curiosity. This lifting action can communicate a range of emotions, from astonishment to intrigue.

Additionally, when the frontalis muscle is relaxed or lowered, it can contribute to a more serious or stern expression. This can enhance communication, indicating that the person may be concentrating or disapproving, thus showing a stern gaze. The ability to modulate expressions of surprise and sternness through the frontalis muscle is central to non-verbal communication.