The frontalis muscle is a facial muscle located in the forehead region. It is a thin, broad muscle that extends from the eyebrows to the top of the skull. The frontalis muscle is responsible for raising the eyebrows and wrinkling the forehead. It works with other facial muscles to produce various facial expressions, such as surprise, worry or concentration. The frontalis muscle is innervated by the frontal branch of the facial nerve (cranial nerve VII).