The muscles of the upper airways.

The upper airways are a complex structure with multiple functions; many of the muscles participate in the act of respiration. The neural control of upper airway muscles is distinct from that of chest wall muscles under a variety of circumstances. Coordinated activation of upper airway muscles, both regionally and inter-regionally, results in changes in upper airway size and resistance, alterations in the route of airflow, and increases in the ability of the airways to resist collapse. Several disorders have now been described in which neuromuscular drive abnormalities and/or mechanical dysfunction of the upper airways occur, resulting in clinical disease.