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Hiccups seem to have no purpose in adults. Dr Karl explains the anatomy of this really annoying phenomenon.

The hiccup seems to have no purpose in adults, except to be really annoying (Source: Stockphoto4u/iStockphoto)

You almost certainly had your first hiccup before you were born, probably around 11 weeks after you were conceived. It turns out hiccups are essential to the normal lung development of unborn babies. And so unborn babies hiccup for about half-an-hour every day until they get born. However, in adults the hiccup seems to have no purpose, except to be really annoying. So let me tell you about what seems to be the very best ‘cure’ for hiccups.

In 1988, ‘hiccupping’ entered the life of Dr Francis M Fesmire while he working in the emergency department of the University Hospital in Jacksonville, Florida. The medical profession has a time-honoured tradition of “See one, do one, teach one”. And so it was in the spirit of this medical mantra that Dr Fesmire developed his hiccup cure.

(Mind you, not everybody will resort to ‘taking’ Dr Fesmire’s ‘medicine’ keep reading, and you’ll soon know why.)

The story begins with an otherwise healthy 27-year-old muscular man turning up in Dr Fesmire’s emergency department. He’d been hiccupping for 72 hours, at the rate of 30 per minute. The man’s medical history was unremarkable, except for a lifelong history of frequent episodes of hiccupping. None of these attacks ever lasted more than two hours, and all of them had resolved spontaneously. But this episode had been running for 72 hours, and he was exhausted.

There is a wise old saying in medicine: “If there is one single cure for something it probably works, but if there are many cures they hardly ever work.”

Hiccups are an excellent example of this. There are almost as many so-called ‘cures’ as there are possible causes. Cures include drinking water from the wrong side of a cup, breathing in and out of a paper bag sprinkled with vinegar, and even chewing frozen raspberries. If you are lucky enough to find something that works for you, be very happy but don’t assume that your cure will work for everybody else.

But what is hiccupping anyway?

The short explanation is that a hiccup happens when your diaphragm muscle contracts abruptly. So you breathe in suddenly, and a little bit later, your vocal cords snaps shut. This interrupts the airflow into your lungs, so giving the characteristic ‘hic’ sound of the hiccup.

The longer explanation is that the hiccup is a complex, patterned and co-ordinated motor act of several groups of muscles. It involves your mouth, diaphragm and lungs, and larynx. It also involves nerves – and a little further on in this story, a nerve called the vagus nerve will become very important.

The very first muscle activity in a hiccup is that both the roof of the mouth and the back of the tongue begin to lift up.

Next, the diaphragm gets involved. The diaphragm is a curved muscle in the shape of a half dome. It connects to the bottom of your ribs at the front of the thorax and then it curves back and downwards to join onto your lower back. The diaphragm separates your lungs which are above it, from your gut which is below it. When it contracts, it pulls your lungs downwards creating ‘suction’, causing you to breathe in.

Finally, your larynx (or voice box) in your throat joins the party. Millions of years ago in evolution, your larynx ‘captured’ control of your flowing air, so that you could make speech. As the air leaves your lungs it passes through the larynx and then through your mouth. Both your larynx and your mouth do very complicated adjustments to the outgoing air to make intelligible sounds and to produce words. In your larynx are the vocal cords, which can be fully open, open just a little bit, or, as at the peak of a hiccup slammed tight shut.

You can see that there’s a whole bunch of muscles involved in this complicated thing that we call a hiccup. And our new-best-friend-for-ever, the vagus nerve, is responsible for controlling many of them, and so is implicated in causing hiccups. Fooling around with the vagus nerve could cure them

At least, that’s what occurred to Dr Fesmire when he was attempting to treat an exhausted patient who’d been hiccupping at a steady rate of once every two seconds for some 72 hours.

How would he bring this poor man some relief?

Well, I’ll talk more about that, next time

Tags: anatomy

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Published 28 August 2012

2012 Karl S. Kruszelnicki Pty Ltd

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Comments for this story are now closed. If you would like to have your say on this story, please email ABC Science

30 Aug 2012 3:40:42pm

really just end like that? shesh!

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31 Aug 2012 9:11:27am

Read first part of Hiccupping story from 28-08-12. Sort of very disturbed at the idea of mcking with the vagus nerve. It controls the involuntary breathing responses. if you damage it, you then have to either be assisted in breathing for life or have to consciously urge yourself to take breath, for life.I do hope this scenario does not pan out in the next installment. Paul

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06 Sep 2012 11:46:53am

Then I ask again.

If such semi-external treatment can be used to interrupt chronic problems such as atrial fibrillation, are they not a more acceptable solution than the drugs currently used?

Untreatable AF and its regime of medication already leave the patient with the symptoms you describe.

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05 Sep 2012 11:59:57pm

Never fails:
Ask the prson with hiccups to stand in front of you and stare into your eyes. Keep staring, keep staring, don’t look away, keep staring. Bingo, hiccups are gone. I went all through college with that, and got to meet a lot of pretty girls as well… But seriously, it really does work.

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08 Sep 2012 12:58:05pm

That’s a complicated explanation for a simple action. An imbalance of CO2 and O2 in the lungs creates a reflex action to correct this imbalance. My cure: Breathe all air out of lungs, hold for ten seconds, breathe normally. Don’t need a story about (fixing) muscles and nerves and tendons.

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