The nose and paranasal sinuses.

The airways should be considered as a functional unit. Indeed, disorders involving the upper respiratory tract (URT) spread to the lower respiratory tract (LRT). Modern functional anatomy divides URT in three, mutually dependent, junction boxes: i) the ostio-meatal complex (OMC), ii) the spheno-ethmoidal recess (SER), and iii) the rhinopharynx (RP). The first is the most interesting as it joins the anterior paranasal sinuses with the nose. The correct ventilation and the effective mucociliary clearance of these three pathophysiologic junction boxes condition the healthy physiology of the entire respiratory system. The OMC, SER and RP obstruction is the first pathogenic step in the inflammatory cascade of the rhino-sinusal-pharyngeal disorders. The inflammation of the respiratory mucosa is the main pathogenic factor for airway obstruction that may be generically defined as a heterogeneous group of pathologies. Moreover, the bacterial biofilms are an important local cause of recurrent diseases: they are a strategic modality of survival set up by bacteria and the main cause of their resistance to systemic antibiotic therapy.