trachea

The trachea is the main windpipe — a flexible tube about the width of a thumb that carries every breath from the voice box down toward the lungs. Run a finger down the front of your neck below the Adam’s apple and you can feel its firm, ridged front.

Those ridges are C-shaped rings of cartilage that hold the airway open so it never collapses when you inhale, while the soft, muscular gap at the back lets the oesophagus behind it expand during swallowing. The inside is lined by mucus-producing cells and cilia that continuously sweep trapped dust and germs upward to be cleared.

At its lower end, around the level of the breastbone, the trachea splits into the right and left main bronchi at a ridge called the carina. The trachea is the airway secured by a breathing tube during intubation or by a surgical opening called a tracheostomy.