Final answer:
A person moving their jaw to the side is performing the muscle action known as lateral excursion.
Step-by-step explanation:
A person moving their jaw to the side is performing the muscle action known as lateral excursion. Lateral excursion refers to the movement of the mandible (lower jaw) to either side, away from the midline of the face. This movement is facilitated by the lateral pterygoid muscles, which are responsible for controlling the side-to-side movement of the jaw.
Learn more about Jaw movement