The larynx lies between the pharynx and the trachea, and is made up of 5 pieces of cartilage which serve to open the glottis. The larynx not only allows the horse to vocalize, but also prevents aspiration of food and helps to control the volume of air inhaled. The trachea is the tube which carries air from the oral cavity and into the lungs, and is about in length in the adult. It is held permanently open by 50–60 "C"-shaped rings of cartilage, in diameter.