Describe the pathophysiology of obstructive sleep apnea

Describe the pathophysiology of obstructive sleep apnea.

Under normal circumstances breaths are initiated by contraction of the diaphragm and intercostal muscles, thereby increasing the thoracic size. Negative pleural pressure results and is transmitted from the lower airways to the pharynx. The pharynx consists of mucosa and soft tissues that lack bony attachments, allowing them to move readily. Negative pressure in the pharynx draws these tissues into its lumen, as if the pharynx were imploding. If unopposed, upper airway obstruction would result. Compensation for such soft tissue movement is accom-plished by constricting the upper airway dilator muscles, which maintain upper airway patency. Upper airway dila-tor muscles include the tensor palatini, which brings the soft palate off the nasopharyngeal wall, the genioglosssus, which advances the tongue off the oropharyngeal wall, and the hyoid muscles, which move the epiglottis off the laryngopharyngeal wall. During sleep, MO patients lose control of their upper airway dilator muscles and upper airway obstruction results.