Sinuses are openings in the bones around your nose. Four pairs of sinuses are connected to the nose by small openings. These sinuses are located behind the cheekbones, alongside your nose, and above your eyebrows.
Humans produce one liter of fluid per day that cleanse the passageways and provide necessary moisture to the lining of each sinus. Tiny little hairs, called cilia, line the sinus membranes and flush the fluid through in a constant carwash-like motion. Under normal conditions, air passes in and out of the sinuses and mucous fluid drains from the sinuses into the nose.
