The trachea is the tube in the throat that connects the mouth and nose to the lungs. It is also called a windpipe, and its function is to transport the air a person breathes in through his nose or mouth into the lungs. Without the trachea, the lungs do not receive oxygen, and humans cannot survive.
According to WebMD, the trachea is approximately 4 inches long and less than 1 inch in diameter. It sits directly underneath the larynx, also known as the voice box, and it extends down behind the breastbone. Once it reaches the end of the breastbone, it splits into two tubes called bronchi, which are the main passageways into the lungs. One bronchus is attached to the left lung, and the other is attached to the right lung.
Approximately 20 rings of thick cartilage surround the trachea. These rings are made of tissues and muscle, and they protect the trachea and keep it from closing shut. The inside of the trachea is smooth and moist. When a person breathes in through his nose or mouth, the trachea gets slightly wider and longer. With each exhale, it returns to its normal size.
Choking occurs when an object gets stuck in the trachea. In many cases, the natural coughing reflex that begins when small items get stuck in the windpipe can dislodge the item.