ABSTRACT
The cough reflex is a protective mechanism that helps clear the airways of secretions and foreign substances. Mechanical or chemical stimulation of receptors in the larynx, trachea, carina, and bronchi initiates the cough reflex1. Afferent impulses from the airway receptors travel mainly through the vagus nerves to the medulla, which triggers a sequence of events. An initial inspiration is followed by closure of the glottis; then, forceful contraction of the expiratory muscles sharply raises intrathoracic pressure; finally, the epiglottis and vocal folds suddenly open widely, allowing air to explode out of the lungs and carry irritant material toward the pharynx. The strong lung compression narrows the airways, further increasing
Table 21 Common causes of coughing.
