The sinuses are four and take their name from the bone in which there are:
The sinuses are in communication with the nasal cavities through openings such hosts to allow the passage in the nose and throat of mucus produced by mucus lining of the sinuses.
In case of sinusitis, the sinuses inflamed mucosa swells and produces excessive amounts of mucus. Swelling of the mucosa results in a narrowing of the hosts that hinders the normal drainage of mucus into the cavity of the nose and mouth.
The stagnant mucus in large quantities within the sinuses is a breeding ground for bacteria, fungi or viruses from the nose or throat can reach the sinuses, in which case it overlaps the infection to inflammation.
Sinusitis can be triggered by a common cold or any other factor that leads to inflammation of the mucosa of allergic rhinitis sufferers have a higher likelihood of developing chronic sinusitis.
In rare cases, sinusitis can be due to the presence of nasal polyps (small growths in the nasal mucosa and / or sinuses), septal deviation or infection of upper dental arch.
In subjects under conditions of immunodeficiency (i.e. with weakened immune systems) as well as in chronic forms, is more common that it is a fungus to cause disease.