Which facial muscle is primarily responsible for producing horizontal wrinkles across the forehead when it contracts?

• A. Zygomaticus major
• B. Orbicularis oculi
• C. Frontalis (frontal belly of occipitofrontalis)
• D. Corrugator supercilii

Answer: (C)

Verified step by step guidance

1. Identify the function of each listed muscle in relation to facial expressions and forehead movement.
2. Understand that horizontal wrinkles across the forehead are caused by the raising of the eyebrows and movement of the forehead skin.
3. Recall that the frontalis muscle, which is the frontal belly of the occipitofrontalis, is responsible for elevating the eyebrows and creating horizontal forehead wrinkles.
4. Note that the zygomaticus major primarily elevates the corners of the mouth (smiling), the orbicularis oculi controls eyelid closure, and the corrugator supercilii draws the eyebrows medially and downward, producing vertical wrinkles between the eyebrows.
5. Conclude that the frontalis muscle is the primary muscle producing horizontal forehead wrinkles when it contracts.