Phrenic

... decrease and carbon dioxide increase in your blood. As soon as a determined level is crossed, the sensors inform your brain which activates your phrenic nerve and generates an inspiration. You breathe, and ... (see upper paragraph) You can train in order to hold your breath for a longer time. ...

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... stomach and movement of stomach acid into the esophagus. After that, a disease or irritation in the thorax could be to blame. Irritation of the phrenic nerve (the nerve to the diaphragm) or the diaphragm is often cited as a cause of hiccups, but this is only speculation about the exact mechanism. ...

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