Which muscle is responsible for causing wrinkles across the forehead?

The muscle that causes wrinkles across the forehead is the frontalis. This muscle is located on the forehead and is responsible for raising the eyebrows and wrinkling the skin of the forehead. When the frontalis muscle contracts, it pulls the forehead skin upward, resulting in the horizontal lines or wrinkles that can appear due to expressions like surprise or concern.

In contrast, the orbicularis oris is primarily responsible for movements of the mouth, such as kissing or puckering. The zygomaticus muscles are involved in smiling, as they pull the corners of the mouth upward. The temporalis muscle is associated with the movement of the jaw and does not influence the wrinkling of the forehead. Therefore, the frontalis is the key muscle responsible for creating forehead wrinkles through its actions.