Hiccups are a sound produced by an unintentional movement of the diaphragm, followed by rapid closing of the vocal cords. The diaphragm is the muscle that separates the abdominal cavity from the chest cavity.
Hiccups can develop when a stimulus triggers the nerves that contract the diaphragm. Air is then inhaled involuntarily. This lowers the diaphragm and allows bursts of air into the lungs. The air closes the vocal cords and creates the characteristic hiccup sound.
The cause of the diaphragm contractions is unknown. The condition can be related to:
Sometimes hiccups are a complication of a condition, such as pneumonia. They may occur following chest or stomach surgery. A brain tumor or stroke can interfere with the breathing center in the brain and cause hiccups.