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NCI Dictionary of Cancer Terms


sphenoid sinus  listen  (SFEE-noyd SY-nus)

  A type of paranasal sinus (a hollow space in the bones around the nose). There are two large sphenoid sinuses in the sphenoid bone, which is behind the nose between the eyes. The sphenoid sinuses are lined with cells that make mucus to keep the nose from drying out.

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Anatomy of the paranasal sinuses; drawing shows front and side views of the frontal sinus, ethmoid sinus, maxillary sinus, and sphenoid sinus. The nasal cavity and pharynx (throat) are also shown.