MedlinePlus Medical Encyclopedia: Sinusitis

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Sinusitis

Sinusitis refers to inflammation of the sinus cavities, which are moist, hollow spaces in the bones of the skull. There are four pairs of sinuses:

Frontal sinuses
Maxillary sinuses
Ethmoid sinuses
Sphenoid sinuses (not shown in illustration)

If the opening from a sinus cavity becomes plugged, the flow of mucus is blocked and pressure builds up, causing pain and inflammation.

Update Date: 1/23/2008

Updated by: Alden J. Pearl, MD, Clinical Assistant Professor, Department of Otolaryngology, State University of New York Health Science Center at Brooklyn, Brooklyn, NY. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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