Trachea

What and where is it?

The trachea, or windpipe, is the main airway to the lungs and part of the respiratory system. It lies below the larynx, with the oesophagus directly behind it.

What it does

• An air passage: it carries oxygen-rich air to the lungs and carbon dioxide back out.
• Staying open: cartilage supports its wall so it does not collapse.
• Cleaning: mucus traps particles and germs, and cilia push it upwards to be swallowed or coughed out.

How it works

1. 1
   Nose or mouthAir enters and is moistened and warmed.
2. 2
   LarynxAir passes through it into the trachea.
3. 3
   TracheaCarries air downwards while its mucus catches particles.
4. 4
   BronchiAt the level of the fifth thoracic vertebra the trachea divides into right and left bronchi, which enter the lungs and branch into thinner tubes ending in the air sacs.

Links with other organs

The lungs

• It delivers air to them through the two bronchi.

Oesophagus

• It lies directly behind the trachea, whose soft back wall lets it expand. When you swallow, the epiglottis drops to keep food out of the airway.

Thyroid gland

• Its two lobes sit on either side of the trachea, below the larynx.

Common problems that affect it

MedlinePlus lists tracheal problems including narrowing, inflammation and some inherited conditions.

A tracheostomy — a surgical opening in the neck that helps breathing — may be needed for swallowing problems, conditions that affect coughing or airway blockages, or in critical care when a breathing machine is needed.

Tests used to study it

The airways can be seen from the inside with a bronchoscopy:

• EndoscopyProcedure