This contraction of the diaphragm then causes an immediate and brief closure of the vocalcords, which produces the characteristic sound of a hiccup. What actually causes the hiccup is difficult to say - in most instances, there is no obvious cause.

Attacks of the hiccups seem to be associated with a few different things: eating or drinking too fast; being nervous or excited; or having irritation in the stomach and/or throat.

In some extremely rare cases, theunderlyingcause of hiccups can bepleurisy(inflammation of the membrane lining of the lungs and chest cavity),pneumonia,certain disorders of the stomach oresophagus,pancreatitis,alcoholism,orhepatitis. Any one of these conditions can cause irritation of the diaphragm or of the phrenic nerves that supply the diaphragm - it's the irritation that causes the hiccups.

Still, the cause of most attacks of the hiccups remains a mystery.

hiccup:打嗝
diaphragm:横隔膜
involuntarily:不自觉地
contract:收缩
abdomen:腹部

cords:声带

underlying:潜在的，根本的
pleurisy:胸膜炎
pneumonia:肺炎
esophagus:食道
pancreatitis:胰腺炎
alcoholism:酒精中毒
hepatitis:肝炎