The trachea is part of the respiratory system. It is a duct of fibrous and cartilaginous or elastic fibro-cartilaginous tissue connecting the larynx to the main bronchi and whose function is to conduct air between these 2 elements. It is the pathway for both oxygen-rich air from the larynx to the lungs during inspiration and for the elimination of carbon dioxide-rich air from the lungs during expiration. The trachea is made up of 15 to 20 horseshoe-shaped cartilaginous rings, which remain quite flexible. The trachea is divided into three parts: the mucosa, the submucosa and the adventitia. The surface in contact with the air, the mucosa, is lined with a respiratory epithelium composed of ciliated cells (allowing to filter dust) and mucus cells which will facilitate the transport and the elimination of waste towards the larynx, where the mucus will be swallowed.