The windpipe, also known as the trachea, is a central component of the human respiratory system. It serves as a pathway, allowing air to travel into and out of the lungs. This cartilaginous tube ensures a continuous flow of air for breathing.
What the Windpipe Is and Where It’s Located
The windpipe, or trachea, is a tube extending from the voice box (larynx) down into the chest. It sits in the lower neck and upper chest, positioned in front of the esophagus, the tube responsible for carrying food. In adults, this tube measures 10 to 12 centimeters (about 4 to 5 inches) in length and 2 centimeters (about 1 inch) in diameter. It is supported by a series of 16 to 20 C-shaped cartilage rings, giving it a distinctive D-shaped appearance.
How the Windpipe Works
The windpipe is a passageway for air to and from the lungs. When a person inhales, air travels from the nose or mouth, through the voice box, and down the windpipe into the lungs. Conversely, when exhaling, carbon dioxide-rich air moves back up the windpipe and out of the body.
The C-shaped cartilage rings maintain the windpipe’s open structure, preventing collapse, especially during inhalation when air pressure changes. The inner surface of the windpipe is lined with mucosa, a moist tissue with specialized cells. Goblet cells produce mucus, which traps dust, allergens, and other debris from inhaled air. Tiny, hair-like cilia also line the windpipe, sweeping this mucus and trapped particles upward towards the throat, where they can be swallowed or expelled, preventing them from reaching the lungs.
Protecting the Airway and Its Connections
The windpipe has protective mechanisms to ensure air travels to the lungs without interference from food or liquids. The epiglottis, a small flap of tissue in the voice box, covers the opening of the windpipe during swallowing. This action diverts food and drink into the esophagus, preventing them from entering the airway. If food or liquid accidentally enters the windpipe, it triggers a cough reflex to expel the foreign material.
The C-shaped cartilage rings of the windpipe are incomplete at the back. This design allows the esophagus to expand slightly when larger pieces of food pass through it, ensuring smooth digestion without compressing the windpipe. At its lower end, the windpipe divides into two main tubes called bronchi, one leading to each lung. This branching point, known as the carina, marks the direct connection between the main airway and the lung’s vast network of smaller air passages.