You are engrossed in a crime thriller, but in your excitement at discovering the “crime novel,” you turn the page too quickly and slice the skin of your index finger. Pain shoots through the paper cut and you gasp, not because you just found out the butler did it, but because the tiny cut hurts so much.
Why are paper cuts so painful?
It’s a combination of our hands, which are incredibly sensitive to pain, and the edges of paper, which are surprisingly jagged.
Human hands and fingers carry a high concentration of nerve Cells called nociceptors that respond to signals released by damaged cells BrainFacts.org (opens in new tab). Paper cuts primarily trigger “mechanical nociceptors” that sense cellular damage from pressure, cuts, and punctures, as opposed to damage caused by extreme temperatures, for example. To a lesser extent, paper cuts can also activate nociceptors that are sensitive to chemical irritants, such as: B. Bleach used to whiten paper. These nerve cells can cause itching around a paper cut.
Activated nociceptors release a flood of electrical signals that travel through bundles of nerve fibers and into the spinal cord; Nerve cells in the spinal cord then transmit these signals to the Brain. Ultimately, the signals reach a region of the folds of the cerebral cortex responsible for touch, temperature, and pain sensations, known to medical sources as the somatosensory cortex StatPearls (opens in new tab).
Related: The five (and more) human senses
The somatosensory cortex curves like a headband across the brain surface, with different regions of the headband representing different parts of the body. Hands and fingers are so packed with touch and pain-sensitive cells that the dedicated areas of the headband are huge compared to those of less sensitive parts of the body, like the torso. The mouth and tongue occupy a similarly expansive area of the headband, which explains why cutting open the tongue when licking an envelope is also very painful.
But it’s not just the anatomy that makes paper cuts oddly painful; the paper itself also contributes to the agony. Although it looks smooth to the naked eye, on a microscopic level, the dried, compressed wood fibers in the paper make the edges of the material quite rough cosmos (opens in new tab). This rough texture causes more extensive cell damage than a straight, clean edge.
However, the jagged edge of the paper usually only cuts through the top two layers of skin – the epidermis and dermis – and therefore causes little to no bleeding. This reduces the chance of the cut becoming sealed with clotted blood. As a result, the damaged nerve fibers remain exposed to the weather for a longer period of time and shoot out pain signals when touched.
To treat a scissors cut, clean the wound with soap and water; apply an antibiotic ointment to prevent infection; and cover it with a bandage to cushion and block dirt, as per Ohio State University Wexner Medical Center (opens in new tab). Most paper cuts heal within two to three days, but if the cut doesn’t improve in that time, it’s best to see a doctor and have it checked for signs of infection.