Stomach Vagus nerve Phrenic nerve Brainstem 1 A hiccup strikes when the vagus nerve and the phrenic nerve, both originating from the brainstem send strong signals to the respiratory muscles.
External intercostal muscles Diaphragm Lung Glottis Inhalation Glottis open 2 The external intercostal muscles and the diaphragm contract, causing a forceful inhalation. Trachea
Glottis closed The glottis quickly slams shut. Air rushing past its leading edges, or vocal cords, causes a high- pitched ‘hic.’ Vocalcords
Trace your family back to the Devonian Period and you’ll find slimy amphibious creatures Following an injury, Charles Osborne (1894-1991) from Anthon, Iowa, had uninterrupted hiccups for 68 years. with behavior similar to today’s tadpoles. At the surface, they gasp for air with primitive lungs. Underwater, the mouth forces water though gills, while a reflex shuts the glottis to keep water out of the lungs. Human hiccups might be a vestige of that ancient amphibian reflex. THE ORIGINAL HICCUPS? A WORLD RECORD Gills Lung Breathing air Glottis closes Glottis opens

SOURCE: BioEssays.