hic!

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This is the anatomy of a hiccup (for my advanced illustration class). I was trying to come up with a topic, so I contacted several of my non-medical-illustration friends and asked them, "Hey, what's something medical that you've never really understood but wanted to see illustrated?" And this suggestion won out.

Here is some accompanying text:

With all the amazingly complex technologies being developed every day, it is astonishing that nobody has yet figured out the common hiccup.

While the exact cause and precise mechanism remain unknown, the basic macroscopic process for the common acute hiccup—though still technically speculation—is pretty well accepted.

Normally, the phrenic nerves, which innervate the diaphragm, begin in the neck and fan out on top of the diaphragm itself (fig. A).

This is all well and good until the stomach—cited as the most common precipitant of hiccups—is distended, either through too much food/drink or a lot of swallowed air. In the first part of the two-part hiccup, the distended stomach presses up against the diaphragm and irritates the phrenic nerve sitting on the other side of the diaphragm (fig. B). The irritated phrenic nerve sends a signal to the diaphragm, and the diaphragm contracts. The contracted diaphragm more-or-less pulls the bottoms of the lungs down, and air must rush in to fill the new space of the now-expanded lungs (fig. C).

Less than a second after the beginning of the influx of air, part two of the process begins. While air is rushing through the space between the two vocal cords (fig. D), muscles connected to the arytenoid cartilages (which are connected to the vocal cords) contract. The vocal cords snap shut, and the air that was rushing into the larynx can do nothing but bounce off, creating an audible “hic!” (fig. E).

And there we have it: the current theory behind a hiccup.

As it turns out, there was one scholarly article written about this subject in, ohhh, 1993? that basically seems to be the last time anyone studied the acute hiccup, and the UIC library didn't have it.

Sooooooo here we are.



[Adobe Illustrator]