The shape of your nasal cavity could be causing your chronic sinusitis. The nasal septum is the wall dividing the nasal cavity into two parts; it is made up of a central supporting skeleton covered on each side by mucous membrane. The front portion of your nasal septum is a firm but bendable structure made mostly of cartilage and is covered by skin that has a large supply of blood vessels. The perfect nasal septum is exactly midline, separating the left and right sides of the nose into passageways of equal size.
Estimates are that 80 percent of all nasal septums are not centered, a condition that is usually not noticeable. A "deviated septum" occurs when the septum is severely moved away from the midline. The most common symptom from a crooked septum is open mouth breathing as a result of difficulty breathing through the nose. Symptoms are usually worse on one side, and sometimes occur on the side opposite the bend. In some cases the crooked septum can hinder the drainage of the sinuses, resulting in chronic sinus infections.