We all know that pain: the sharp, burning sensation having sliced through the skin on your finger. Ouch! But why are paper cuts so painful?
Our hands are the window into the world of touch and as such are packed with nerve fibres, with many more present than in any part of the rest of your body. This makes them a prime target for pain!
These nerve fibres are called "nociceptors" and they send vital information to the brain via the spinal cord. This information includes pressure, temperature and chemical cues - all usually manifesting themselves as what we would call "pain".
Mechanical nociceptors respond to pressure and can detect breaks in the skin's surface. It is these receptors that are responsible for relaying the pain signal when afflicted by a paper cut.
In comparison to a cut from a sharp object, such as one with a kitchen knife, paper cuts are a relatively shallow and irregular, with much more microscopic damage, due to the serrated, dull nature of the paper's edge. The microscopic damage is also exacerbated as paper fibres can be left behind in the wound.
As the most sensitive of the nociceptors are also closer to the surface of the skin, paper cuts cause the maximum amount of damage, closest to the highest density of the most sensitive receptors.
Being a shallow cut, there also tends to be very little blood with paper cuts meaning that there is rarely a significant clot. As such the cut is more open to the elements, and airborne particulates or microscopic irritants on surfaces can enter the wound, furthering the damage and increasing the pain suffered.
Furthermore, as we regularly use our fingers for a variety of functions, the stress on the skin can keeps the wound open for much longer than it would elsewhere on the body.
Pain Relief and Healing
If you the wound is pressed firmly the reception of the pain signal in the brain will be overwhelmed by pressure signal, effectively acting as pain relief. You may be familiar with this phenomenon when you rubbed your leg after falling over when you were young!
The paper cut can also be relieved by sealing the wound using a liquid plaster or even honey. This prevents any irritants from entering the wound whilst also preventing infection and getting healing underway.