What action does zygomaticus major perform?

The zygomaticus major muscle is primarily responsible for facilitating facial expressions, specifically smiling. Its action involves pulling the corners of the mouth upward and laterally, which contributes to the characteristic expression of joy or happiness. This muscle originates from the zygomatic bone and inserts into the corner of the mouth, allowing it to effectively elevate the angle of the mouth when it contracts.

Understanding the role of the zygomaticus major is essential in the context of facial anatomy and the mechanics of expressions. Other muscles, such as those involved in mouth closure or jaw movement, serve different functions in the facial and oral regions. Therefore, recognizing the specific action of the zygomaticus major helps in distinguishing its role from those of neighboring muscles and their contributions to overall facial expression and movement.