Trachea (Windpipe): The trachea is a large, single tube that begins at the larynx (voice box) and travels down the neck and into the chest. It consists of flexible cartilage rings that keep the airway open while allowing for movement during breathing.

Bronchi (Primary Bronchi): When the trachea enters the chest, it divides into two primary bronchi, one bronchus leading to each lung (left and right lungs). The bronchi continue to branch further into smaller tubes as they enter the lungs.