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. 2012 Jun;34(6):451-3.
doi: 10.1002/bies.201100194. Epub 2012 Feb 29.

Hiccups: a new explanation for the mysterious reflex

Daniel Howes  1
Affiliations
Free PMC article

Hiccups: a new explanation for the mysterious reflex

Daniel Howes. Bioessays. 2012 Jun.
Free PMC article

Abstract

The hiccup may have evolved to remove swallowed air from the stomach, which may help suckling mammals to consume more milk.

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Figures

Figure 1
Figure 1
The hiccup may have evolved to remove air from the stomachs of young suckling mammals. A: The presence of air (yellow) in the stomach beneath the diaphragm triggers the afferent limb of the reflex, sending signals to the medulla (shown in red). B: Activation of the reflex efferent limb (purple) causes the muscles of respiration to expand the chest (green arrows), while simultaneously closing the opening of the trachea (green X). The result is a sharp drop in pressure in the chest (symbolized by formula image). C: The negative intra-thoracic pressure moves the air bubble to the thoracic esophagus. With relaxation after the hiccup, the air can pass up the esophagus and out the mouth, leaving more room for milk.
See this image and copyright information in PMC

References

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