The human external nose and its evolutionary role in the prevention of obstructive sleep apnea.

Abstract

The purpose of the prominent human external nose remains unclear. The external nose may play a compensatory role in the aerodynamic support of the upper airway, which in humans has been severely narrowed to enable spoken language. During times of decreased muscle tone, the wing-like soft palate may be supported by airflow patterns, creating "lift." Serving as an aiming nozzle, the external nose may, by creating a curvilinear intranasal airflow pattern, adjust the "angle of attack" of airflow contacting the palate, thus enhancing lift and facilitating opening of the nasopharynx. This concept was tested, comparing nasopharyngeal opening and wind speed in curvilinear and linear nonanatomic models. Statistically significant differences were found, with enhanced opening in the curvilinear model. Related findings in hominid nasal bone fossil analysis show that the external nose developed contemporaneous to the development of language. These findings may have clinical implications in the management of obstructive sleep apnea.