text: During swallowing , the backward motion of the tongue forces the epiglottis over the glottis ' opening to prevent swallowed material from entering the larynx which leads to the lungs ; the larynx is also pulled upwards to assist this process .
simplified: During swallowing , the backward motion of the tongue forces part of the larynx called the epiglottis over the laryngeal opening . This is to prevent swallowed material from entering the lungs .