Hiccup, also called hiccough, is an abrupt, involuntary intake of air caused by a spasm of the diaphragm. The diaphragm is a large, powerful, dome-shaped muscle that lies at the base of the chest cavity. It contracts and relaxes like a bellows to aid breathing. Normally, these contractions are rhythmic and gentle. But irritation of organs near the diaphragm, or, sometimes, certain diseases, may cause the diaphragm to contract suddenly. This spasm pulls air into the lungs through the larynx (voice box). The larynx is flanked by the vocal cords and topped by the epiglottis, a movable cap that keeps food from getting into the air passages. The epiglottis closes over the larynx when the diaphragm suddenly contracts. When the spasm of the diaphragm pulls air into the larynx, the air forcibly strikes the closed epiglottis and causes a movement of the vocal cords. These actions result in the hic sound that we hear.
The hiccup (spasm) may occur several times in a minute. Hiccups may last for several hours, or, rarely, for several days. People can sometimes stop ordinary hiccups by breathing deeply, by holding their breath, or by breathing into a paper bag.
