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Paranasal sinuses are air-filled spaces, communicating with the nasal cavity, within the bones of the skull and face. Humans possess a number of paranasal sinuses, divided into subgroups that are named according to the bones within which the sinuses lie:
Paranasal sinuses form developmentally through excavation of bone by air-filled sacs (pneumatic diverticula) from the nasal cavity. This process begins prenatally, and it continues through the course of an organism's lifetime.
Sinuses in animals
Paranasal sinuses occur in a variety of animals (including most mammals, birds, non-avian dinosaurs, and crocodilians). In non-humans, the bones occupied by sinuses are quite variable.
The biological role of the sinuses is debated, but a number of possible functions have been proposed:
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.
The paranasal sinuses are not the only sinuses within the skull: the mastoid cells in the mastoid bone around the middle ear are also a type of sinus.
Sinus is a Latin word meaning a fold or pocket; in particular the front pocket in a toga.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Paranasal_sinus". A list of authors is available in Wikipedia.|