Nasal and oral airflow resistors. Site, function, and assessment.

Major respiratory resistors situated at the nasal and oral portals are described, and the part they play in disrupting laminar flow of inspiratory air and facilitating the mucosal contact and mixing essential for effective cleansing, warming, and humidification is discussed. The resistors also determine the distribution of oronasal airflow. The contribution of structural and mucovascular elements to nasal airflow resistance is examined and the place of history, rhinoscopy, and rhinomanometry in clinical assessment of nasal patency and its variation in health and with age, race, and disease, is discussed.