What causes hiccups?
Ask the doctor
We know what hiccups are, but not why they occur. Each of us has a flat plate of muscle just beneath our lungs, separating our chest from our abdomen. It's called the diaphragm, and it helps us breathe: when it moves downward, it causes the lungs to pull in air through the nose and mouth. And when it moves upward, it forces air out of our lungs. The movement of the diaphragm is directed by the brain, which sends signals down nerves that end in the diaphragm. A hiccup occurs when the brain sends a signal for the diaphragm to shift forcefully downward, suddenly pulling a lot of air into the back of the throat. The sudden change in pressure causes a narrow area in the throat to temporarily snap shut, causing the "hic" sound of a hiccup. Why the brain sends the signals that cause hiccups, however, is a mystery.
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