The Probert Encyclopaedia of Medicine

COUGH

A cough is a sudden and forcible expiration immediately preceded by closure of the glottis or narrowed portion of the box of the windpipe. The force for the action is obtained by a deep breath, then follows the closure of the glottis, succeeded by the expiratory effort forcing open the glottis. The action is performed by the expiratory muscles, that is the abdominal muscles, by whose contraction the diaphragm is forced up, and the muscles of the chest, by which the ribs are pulled down. The cavity of the chest being thus diminished air is driven out of the lungs.

The object of the cough is usually to expel any foreign material in the lungs or air-tubes. The offending material may be there present as the result of inflammation, catarrh, etc. It may also have gained entrance from without. Thus the irritating material may be merely some food or drink which has slipped into the larynx, or it may be dust, etc, in the air inhaled, and the cough is the means of expelling the intruder. But a cough may also be produced when there is no irritating material present. The larnyx or windpipe may be in an inflamed and irritable condition, in which state even the entrance of cold air will excite coughing. Moreover, cough may be produced by irritation of nerves, distant from the lungs and air-passages, by what is called reflex action. Thus irritation of the stomach, irritation connected with the ear, irritation of certain nerves by pressure of growths, etc, may produce a cough, when the respiratory organs are not directly affected at all. Irritation at the back of the throat, as of the tickling of a long uvula, and so on, also produces it.
Research Cough