What action does the buccinator muscle perform when chewing?

The buccinator muscle plays a vital role in the process of chewing, primarily by compressing the cheeks against the teeth. This action helps keep food between the teeth for proper grinding and prevents it from accumulating in the vestibule of the mouth, which is the space between the gums and the inner lining of the cheeks.

The buccinator aids in maintaining the position of food as it is manipulated by the tongue and teeth, facilitating efficient mastication. This muscle is essential for effective chewing and helps create the necessary pressure to move food smoothly through the oral cavity.

While the other actions listed involve facial movements, they are not functions of the buccinator muscle. Elevating and protruding the lips is primarily the function of the orbicularis oris muscle, retracting the corners of the mouth is associated with muscles like the risorius, and flaring the nostrils involves the nasalis muscle rather than the buccinator.