What actions does the frontalis muscle perform?

The frontalis muscle, part of the occipitofrontalis muscle group, is primarily responsible for actions involving the forehead and the eyebrows. It elevates the eyebrows, which allows for expressions of surprise or curiosity. This elevation creates a noticeable lift in the skin of the forehead, contributing to the appearance of an arched brow. Additionally, as the frontalis muscle contracts, it causes wrinkles to form on the skin of the forehead. This wrinkling is associated with various facial expressions, such as frowning or thinking deeply.

Given these functions, both the elevation of the eyebrows and the wrinkling of the forehead skin are direct actions of the frontalis muscle, making the choice that encompasses both actions correct. The other options do not accurately describe the function of the frontalis; for instance, retraction of the scalp is not a function of this particular muscle.