The tracheobronchial tree is the structure from the trachea, bronchi, and bronchioles that forms the airways that supply air to the lungs. It is within the neck and the chest. The structure looks like a tree because the trachea splits into the right and left mainstem bronchi, which "branch" into more progressively smaller structures. The lining of the tracheobronchial tree consists of ciliated columnar epithelial cells. Injuries to the tracheobronchial tree are potentially fatal because they can interfere with breathing.