Any of the air-filled cavities in the bones surrounding the nose. These include 2 frontal sinuses in the lower forehead; 2 ethmoidal sinuses between the eyes; 2 maxillary sinuses in the cheekbones; and the sphenoidal sinuses in the skull behind the nose. Mucus drains from each sinus along a channel that opens into the nose. Infection of a sinus causes sinusitis.
Sinus, facial |
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