Trachea

The trachea, or windpipe, connects with the larynx above to the bronchi of the lungs. It lies behind the esophagus. Its purpose is to conduct air to and from the lungs. It is a rigid tube composed of tough membrane supported by a series of circular cartilages to prevent it from collapsing. The inner surface of the trachea is lined with mucus secreting goblet cells and contains hairlike cells (cilia) that act to capture and expel foreign particles caught in the trachea. As the trachea enters the thorax it divides to join the two bronchi of the lungs