The frontalis muscle is a thin, flat muscle located in the forehead region. It is part of the epicranius muscle group and is responsible for raising the eyebrows and wrinkling the forehead. This muscle plays a key role in facial expressions, particularly in conveying surprise or curiosity. The frontalis muscle originates from the galea aponeurotica, a fibrous tissue covering the skull, and inserts into the skin of the forehead. It is innervated by the facial nerve, which allows for voluntary movement. Proper functioning of this muscle is essential for effective non-verbal communication.