Other Definitions
paranasal sinus (dict)
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Paranasal SinusThe paranasal sinuses are eight (four pairs) air-filled spaces, or sinuses, within the bones of the skull and face. These are divided into subgroups that are named according to which bones they lie under; The function of the sinuses is not entirely clear, but they may fulfill any or all of the following: - Decreasing the relative weight of the front of the skull
- Helping to warm and humidify inhaled air before it reaches the lungs
- Increasing resonance of the voice
- Providing a buffer against blows to the face
The paranasal sinuses are joined to the nasal cavity via small orifices called ostia. These become blocked relatively easily by allergic inflammation, or by swelling in the nasal lining which occurs with a cold. If this happens, normal drainage of mucus within the sinuses is disrupted, and sinusitis may occur.
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