Paranasal sinuses are air-filled pockets located in the head. There are four pairs of sinuses:
- Maxillary sinuses
- Frontal sinuses
- Ethmoid sinuses
- Sphenoid sinuses
How do healthy sinuses work?
When you breathe in air, mucus in the sinuses humidifies the air and collects bacteria and pollutants.
Tiny hairs lining the sinuses move the mucus (with pollutants) out of the sinus, into your throat.
You then swallow the mucus, and your stomach acid destroys the bacteria and pollutants.
Colds, allergies, environmental irritants or other conditions can slow or block natural drainage, and irritate the sinus lining. This, in turn, can lead to swelling, additional blockage, and sinusitis.