College of Massage Therapists of British Columbia (CMTBC) Practice Exam

Which of the following muscles is important for smiling?

1. Zygomaticus major

2. Frontalis

3. Occipitalis

4. Buccinator

The correct answer is: Zygomaticus major

The zygomaticus major is the muscle primarily responsible for smiling. This muscle originates from the zygomatic bone and extends to the corners of the mouth. When it contracts, it pulls the corners of the lips upward, creating the expression associated with smiling. The frontalis muscle, located in the forehead region, primarily raises the eyebrows and creates horizontal wrinkles across the forehead, which contributes to other facial expressions but not specifically smiling. The occipitalis, part of the epicranius muscle group at the back of the head, helps in moving the scalp but does not have any role in the action of smiling. The buccinator is involved in compressing the cheeks against the teeth, aiding in actions like chewing and blowing, but it does not contribute directly to the movement of the lips associated with smiling. Therefore, the zygomaticus major is the key muscle enabling the upward movement of the lips, making it essential for the act of smiling.