Which action is performed by the Frontalis muscle?

• A. Raises eyebrows
• B. Closes jaw
• C. Depresses hyoid
• D. Elevates mandible

Answer: (A)

Raising the eyebrows is the action performed by the Frontalis muscle. The Frontalis, part of the occipitofrontalis, runs from the galea aponeurotica to the skin of the eyebrows. When it contracts, it pulls the skin upward, elevating the eyebrows and creating forehead wrinkles. This is distinct from jaw movements done by the muscles of mastication (such as closing or elevating the mandible) and from muscles that move the hyoid bone (which depress the hyoid). So the Frontalis specifically elevates the eyebrows.