PROCESS OF SNORING: THE UPPER AIRWAY

It is essential to have some familiarity with the anatomy of the upper airway to understand the process of snoring. The upper airway is generally regarded as extending from the opening of the nose and mouth to the large air passage known as the trachea. This main airway then subdivides into progressively smaller airways to facilitate delivery of oxygen to the lungs. The trachea itself is a resilient length of airway, well supported by cartilage and muscle, capable of withstanding collapse during normal breathing manoeuvres and protected to some extent from damage which can be inflicted to this susceptible section of the throat. The nasal and oral passages meet in a segment of the airway known as the pharynx with soft, fleshy and more compliant walls. It is the collapse of components of this section of the airway and subsequent vibration of the soft palate that causes the familiar sound of snoring.

The tone of the upper airway is controlled by several muscle groups. Some of these are under voluntary control such as the tongue and those muscles used for swallowing. Others have more subtle influence and although we have no voluntary control over them, they are essential for maintenance of upper airway integrity.

Inspiratory and expiratory efforts during normal breathing are accompanied by pressure fluctuations in the airway. The downward movement of the diaphragm during inspiration creates a negative pressure which sucks in air through the nose and mouth. Most of our airways are sufficiently reinforced to withstand the tendency to collapse under this pressure, with the exception of the less rigid walls of the pharynx which require an active involvement of muscles to remain open.

The process of breathing is a symphony of muscular coordination with large muscles drawing in air and expanding the chest while smaller muscles work to keep airways dilated. Other muscle groups take over for the reverse process of expiration.

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