Paranasal Sinuses

About the Paranasal Sinuses

The paranasal sinuses are four paired, air filled cavities in the bones of the face and skull, named after the bones that contain them: the maxillary sinuses in the cheeks, the frontal sinuses above the eyes, the ethmoid sinuses between the eyes, and the sphenoid sinuses deep behind the nose. They are lined with mucous membrane continuous with that of the nasal cavity and drain into it through small openings. Their functions are not fully understood but are thought to include reducing the weight of the skull, warming and humidifying inhaled air, contributing to voice resonance, and absorbing impact to protect the eyes and brain. The sinuses develop gradually, with the frontal sinuses appearing in childhood and reaching full size after puberty. Inflammation of the sinus lining, sinusitis, is very common and is often triggered by colds or allergies. Chronic sinusitis and nasal polyps may be treated with endoscopic sinus surgery.