What are the nasal sinuses?

The bones of the face have hollows which we call the (paranasal) sinuses. We do not exactly know why we have evolved with them but they have been theorised as making our skull lighter, acting as an airbag for the brain protecting us such as when we suffer impact to the face, giving a resonant quality to our voice or having an immune function involved in fighting infections. There are four pairs of sinuses as shown in the picture below. These are present in the forehead (the frontal sinuses), between the eyes (the ethmoid sinuses), in the cheek bones (the maxillary sinuses) and behind the back of the nose (the sphenoid sinuses). 




These sinuses each have a lining that makes mucous which discharges through very narrow pathways into the nasal cavity. This mucous travels to the back of our nose and we then swallow it. In fact, we swallow about 1.5 litres each day. 

What problems can we have with the sinuses?

Below are some but not all of the issues that can arise from the sinuses.


When the lining of the sinuses becomes infected, it becomes swollen and may block the narrow passageways that drain the sinuses into the nose.

Sinusitis can occur as acute sinusitis or chronic sinusitis dependent upon the duration of symptoms.

Tumours and cysts

Sometimes other growths or cysts can arise from the lining of the nose and sinuses. These may cause nasal or sinus obstruction, push on surrounding structures such the eye to affect vision, block the tear duct to cause tearing or be of concern for malignancy.

Silent Sinus Syndrome

When the narrow pathways draining the cheek sinuses become blocked, the size of the sinus can shrink in volume. As these sinuses are underneath the eyes, this can cause the eyes to drop and cause double vision.

Sinus barotrauma

If the sinus passageways are blocked, pain can also happen when we change altitude such as when we fly or SCUBA dive. 

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