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  • You know, stubbing your toe hurts.

  • It's right up there with paper cuts and chapped lips, annoying minor injuries that hurt way more than they have any right to.

  • But it turns out there's a good reason why stubbing your toe hurts so much.

  • When you stub your toe, you're slamming it with a force equal to two to three times your body weight.

  • That's about the same force as a karate punch.

  • And since your toe has a tiny surface area, that force can't be spread out, so the pain stays concentrated at the point of impact.

  • It's the same reason it hurts so much more to step on the tiny, pointy end of a thumbtack than the wider, blunt end.

  • But you don't just feel the immediate shock like when you step on a thumbtack.

  • There's that aching throb that comes after.

  • That's because when you stub your toe, you're actually hitting a bundle of special nerve endings called nociceptors.

  • They all fire at once, blaring a danger signal.

  • But some signals travel faster than others.

  • The faster A-delta nociceptors fire the first wave of signal.

  • Which races at 20 meters per second of thousands of densely bundled nerve fibers, and ultimately to your brain.

  • That causes the sharp, sudden pain you feel at the moment of impact.

  • But some nerve fibers called C nociceptors send a slower signal at only 2 meters per second.

  • So after a moment's delay, the second wave of pain signals reach your brain.

  • That's the dull throbbing that lingers on.

  • You can find nociceptors all over your body from your eyes to your bladder.

  • But they're concentrated at the highest densities in parts of your body that you use to explore your environment.

  • Like your fingertips and your lips.

  • That's why accidents like paper cuts and chapped lips can also hurt more than they seem like they should.

  • Now, your toe isn't packed with as many nociceptors as your fingertips.

  • But since there's not much in the way of padding to cushion the blow, it's easy to set those unprotected nociceptors off.

  • And that's no coincidence.

  • Researchers suspect the pain that we feel from mishaps like a stubbed toe might have even saved our ancestors' lives.

  • Back before antibiotics, even the tiniest cut could mean a deadly infection, and feet, which were constantly in contact with dirty, bacteria-infested surfaces, were particularly vulnerable.

  • So the people who had extra-sensitive feet might have been more careful about where they stepped.

  • As a result, they'd be less likely to get infections and would live to pass on their genes.

  • So the next time that you collapse on the floor cradling your aching toe...

  • You can thank your great-great-great-great-great-great-great-great-great-great-great-grandpa for the privilege.

You know, stubbing your toe hurts.

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B1 US great great great nerve signal pain stub

Why Stubbing Your Toe Hurts So Much

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    Liang Chen posted on 2019/03/19
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