ABSTRACT
The structure and the neural control of the upper airway have evolved to serve
four important physiologic functions: (i) respiration, (ii) deglutition, (iii) speech,
and (iv) local immunity. The upper airway is collapsible to accommodate these
functions. During wakefulness, upper airway collapse can be prevented by an
increase in pharyngeal neuromuscular tone (1). However, this mechanism is
decreased during sleep, predisposing the upper airway to obstruction (2).
