Functional endoscopic sinus surgery--I (Anatomy, diagnosis, evaluation and technique).

It has been proved beyond doubt that the causation and perpetuation of disease in the dependent sinuses (maxillary and frontal sinuses) is secondary to disease of the ostiomeatal complex, the primary focus of which is the anterior ethmoid. Based on this concept, functional endoscopic sinus surgery (FESS) aims at correcting the underlying pathology in the ethmoids and helps to re-establish normal ventilation and mucociliary clearance of the dependent sinuses