The Nose and Sinuses

The Nose and Sinuses play an important role to ensure that the air we breathe is filtered, warmed and humidified before it gets to the lungs.

In order to accomplish these tasks the nose and sinuses are equipped with several unique features which are discussed below.

Filtering of the air to remove bacteria, viruses and irritants

The lining of the nose and sinuses contains mucus producing glands and cells which are tipped with microscopic hairs which beat rapidly. These small microscopic hairs are called ‘cilia’ and they extend into the mucus lining and act as the transport mechanism for moving mucus produced at the front of the nose, and in the sinuses, to the back of the throat from where it is swallowed into the stomach.

The mucus that is produced is sticky, and this serves to trap foreign bacteria, viruses, pollens, and other irritants and stop them from gaining entry into the lungs. Mucus also contains several antibacterial enzymes which can destroy these bacteria and viruses.

For a more thorough and diagrammatic explanation please see the following:

Keeping the air and nasal and sinuses tissues moist

The mucus layer provides a barrier off which inhaled dry air can be deflected away from the delicate tissues underneath and this helps stop them being dried out. As the air is deflected off the mucus it picks up moisture and so is humidified before entering the lungs.

Warming the air

The nose has a very well developed network of blood vessels.  These vessels help to warm the cold dry air that is breathed in through the nose.

The sinus cavities

The sinus cavities are large holes in the facial bones. They serve to lighten the skull and to give the voice its tone.

These cavities are lined with the same tissues and structures as the nasal tissues and produce mucus which is transported to the back of the throat from where it is swallowed.

The sinus drainage system is anatomically very narrow and can be complex.  This leads to problems when there is tissue swelling as a result of colds or allergy. Some drainage points can become easily blocked and then mucus and bacteria which are normally transported out of the sinuses cannot escape.  Pressure builds up and this results in the symptoms of sinusitis.

Diagram to show mucus movement in the sinuses and the complex narrow drainage pathways (The yellow lines depict mucus movement)