Sinusitis or rhinosinusitis is the inflammation of the mucous membrane that lines the paranasal sinuses. It commonly occurs as the result of an infection from a virus, bacteria, fungus and sometimes due to allergens or chemicals.
The paranasal sinuses are four pairs of air-filled cavities/spaces located in the skull in the region around the nose and the eyes.
When we breathe in, air enters the sinuses through the nose and this helps to moisten and warm the air that we breathe. Mucus produced normally by the sinuses drains into the nose and protects the body by trapping germs.
But sometimes, bacteria or allergens can cause too much mucus to form, which blocks the openings of the sinuses leading to sinusitis.
The four pairs of paranasal sinuses involved are:
- Frontal sinuses: Located above the eyes, in the region of the eyebrows
- Maxillary sinuses: These are situated in the cheekbone area
- Ethmoid sinuses: Located between the eyes and behind the bridge of the nose
- Sphenoid sinuses: These sinuses are located at a deeper level, behind the ethmoid sinuses