Sinusitis

Sinusitis refers to inflammation of the sinus cavities, which are moist, hollow chambers in the bones of the skull. There are four pairs of sinuses:Frontal sinusesMaxillary sinusesEthmoid sinusesSphenoid 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.

Review Date: 06/02/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital.