Any of the air-containing spaces in the bones of the face. There are four pairs of facial sinuses: the frontal sinuses in the bone of the forehead, just over the eye sockets; the maxillary sinuses in the cheekbones under the eyes; the ethmoid sinuses on either side of the bridge of the nose; and the sphenoidal sinuses directly over the bridge of the nose. The sinuses are lined with mucous membrane that helps trap particles in the air inhaled through the nose; the mucus drains into the nose.
Also known as paranasal sinuses, these are air-filled spaces located in the bones around the nose. The facial sinuses consist of two frontal sinuses in the lower forehead, two ethmoidal sinuses between the eyes, two maxillary sinuses in the cheekbones, and the sphenoidal sinuses situated behind the nose in the skull. These sinuses serve to lighten the skull’s weight and affect the resonance of the voice. Each sinus is lined with a mucous membrane, and mucus from the sinuses drains through a passage that leads into the nasal cavity.