Paranasal sinus

From Free net encyclopedia

The 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 maxillary sinuses, also called the antra, are under the eyes, in the maxillary bones (cheek bones).
• the frontal sinuses, over the eyes, in the frontal bone, which forms the hard part of the forehead.
• the ethmoid sinuses, between the nose and the eyes, backwards into the skull.
• the sphenoid sinuses, in the centre of the skull base.

Biological function

The sinuses probably fulfil a number of functions:

• Decreasing the relative weight of the front of the skull, and especially the bones of the face. The shape of the facial bones is important, as a point of origin and insertion for the muscles of facial expression.
• 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

Ailments

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.

These conditions may be treated by drugs such as pseudoephedrine, which reduce moisture in the sinuses, or by traditional techniques of nasal cleansing. Template:Details

Template:Anatomy-stubde:Nasennebenhöhle fr:Sinus (anatomie) ja:副鼻腔 pl:Zatoki nosowe zh:鼻竇