Background
Mink first coined the term nasal valve in 1903. Initially, he described the nasal valve as the slitlike opening between the caudal end of the upper lateral cartilage and the nasal septum. Since then, the term nasal valve has broadened to include both an internal nasal valve (Mink’s description) and an external nasal valve. The external nasal valve is described as the region caudal to the internal valve, bounded laterally by the nasal alar and medially by the septum and columella.
Nasal valves (internal and external) may function as Starling resistors (collapsible tubes attached to rigid tubes). The transmural pressure increases as the airflow velocity increases, which leads to collapse and a decrease in airflow. This may be a mechanism to prevent large volumes of unheated and unhumidified air from reaching the lower respiratory tract. In individuals with either acquired or congenital external valve collapse, this mechanism functions at too low a transmural pressure, which leads to premature collapse and difficulty with nasal breathing.