Why does stubbing your toe hurt so much?

Here's the science behind why stubbing your toe is oddly excruciating.

You're rounding a corner in your home when a jolt of pain suddenly shoots through your pinky toe. You let out a yelp and find yourself frozen to the spot, desperately waiting for the throbbing in your stubbed toe to subside.

There's no pain quite like ramming your toe into a door frame or table leg, although the resulting injury is typically minor. So why does stubbing your toe hurt so much in the moment? The answer comes down to the quantity and type of nerve fibers in the feet and the force with which you typically stub your toes.

Painful sensations in the body originate in nerve cells called nociceptors, whose fibers plug into the skin, muscles and internal organs and respond to signals released by damaged cells. Different types of nociceptors respond to different types of damage. Touching a scalding-hot pan sets off thermal nociceptors, for example, while stubbing your toe activates mechanical nociceptors, which are sensitive to pressure, cuts and wounds.

When activated, mechanical nociceptors shoot a message from the free nerve endings in your stubbed toe to dense bundles of nerve fibers that feed into the spinal cord. From there, the signals zip up to the brain and pass through an information hub called the thalamus before being forwarded to the wrinkled cerebral cortex.

The part of the cortex that responds to signals indicating touch, temperature and pain curves over the brain, sort of like a headband, and different areas of the headband process sensation in different body parts.

The specific region that deals with the feet and toes lies at the headband's centre, where the two halves of the brain meet, and its size reflects the number of receptors in the feet. The ultrasensitive face, mouth and hands take up the most space in the sensory headband, but the feet still take up a lot of real estate compared with the less-sensitive trunk and limbs.

Not all pain-related signals from a stubbed toe reach the brain at the same time. The initial lightning bolt of pain triggered by the stubbing is relayed by "A-delta fibers" — thin, fat-encased nerve fibers that send signals super efficiently. The dull, aching pain that emerges seconds later arises from less-efficient "C fibers," which have nerve endings that cover a wide area, meaning several toes rather than the tip of one. This pain can worsen if the injury triggers inflammation.

Nociceptors in the feet can be particularly sensitive to physical trauma, like toe-stubbing, because the feet carry little fat that could help soften the blow. What's more, when you stub your toe, you're likely hitting these vulnerable nerve fibers with a force equal to two to three times your body weight, and all that force is concentrated on a tiny surface area.

Thankfully, the intense pain triggered by stubbing your toe usually resolves within minutes or hours.