Why do people Hiccup?
The answer to the question of the cause of hiccups is a strange one, and it lies in our evolutionary origins as both fish and amphibians. The hiccup reflex is a stereotyped twitch involving several muscles in the body wall, diaphragm, neck and throat. A spasm in one or two major nerves that control breathing causes the muscle to contract. First the spasm in the nerves. This is due to our fishy evolutionary history. Our brain can control breathing without our conscious effort. This is done by our brain stem at the boundary between the brain and the spinal cord. This happens in a pattern, the muscles contract in a specific order. The problem is this first evolved in fish and the nerves didn’t have to travel very far from the brain stem as it was surrounded by the gills and throat. In mammals our breathing is now controlled by muscles in the wall of our chest and the diaphragm. Contraction of the diaphragm controls inspiration (breathing in). The nerves (vegas and phrenic) that control th
