What are sinuses?

Sinuses are air-filled spaces in the bones of the face and skull.  There are 4 major sinuses on each side.  The sinuses are located in the cheeks, between the eyes, in the forehead, and behind the nose in the center of the skull.  The sinuses help reduce the weight of the skull.  Normal function of the sinuses requires open nasal cavities that are free of anatomical obstruction, allergies, or other disease.  Sinuses can become for a host of reasons, leading to facial or dental pain, nasal congestion, fever, and infection.  Sinus problems can be chronic and adversely affect quality of life.  Most sinus problems can be alleviated with medical treatments or surgery.