Which face muscle is activated during smiling?

The zygomaticus muscle is primarily responsible for the action of smiling. This muscle is situated at the cheekbone and plays a crucial role in elevating the corners of the mouth. When the zygomaticus contracts, it draws the lip corners upward, which creates a smile. This action is essential not only for expressing emotions but also for social interactions, making it a significant muscle in facial expressions.

In contrast, while the other muscles listed have roles in facial movements, they do not specifically focus on the act of smiling. The platysma, for instance, is involved in movements of the neck and jaw rather than facial expressions. The orbicularis oris surrounds the mouth and is more involved in actions like puckering or kissing. The frontalis muscle, located in the forehead, is responsible for raising the eyebrows and wrinkling the forehead, playing no direct role in the smile itself. Therefore, the zygomaticus muscle's activation is central to the action of smiling.