An important question asked on the Reddit forum ELI5 (Explain like I’m 5) answered for everyone who has had a brain or head injury, an interesting thing to learn about and the kind of thing you wouldn’t think about but are glad to come across:

ELI5: Why is it that when you hit (I.e bang your head on a corner) you instinctively apply pressure with your hands? Why does that seem to help? 

The top answer was this:

‘Your body can only process so much sensation at once. By touching the place that you’ve hurt, you’re basically distracting your brain from the sensation of pain by introducing pressure.

It’s another reason why ice packs can help with pain – not only do they reduce swelling, they introduce the cold sensation and give your brain something else to think about other than the pain.’

To go into more detail someone said it was called the pain/gate theory:

‘To add to the info on pain /gate therory (not really ELI5 anymore)…some nerve fibers are enclosed by a dealy called a myelin sheath. It helps nerves move the signals faster. Pain travels on non-myelinated nerve fibers. It’s why there is a noticeable delay between stubbing your toe and feeling the surge of pain. It takes 1 or 1.5 seconds for the pain signal to travel all the way to your brain for processing.

Meanwhile pressure and vibration travel along myelinated fibers. They simply move faster.

As Bindweed has already clarified, your brain only processes so much signal at once. So you bonk your shin on the coffee table and immediately, instinctively grab or rub it you are sending pressure/ vibration signals on fast nerves to get there before the slow moving pain signals do. Instead of 100% pain signal, you get a mix.

Babies do not have the myelin sheath. It develops in your early years. When the paediatrician is tapping your knee reflex, what he is testing for is myelination. Slow reflex means poor myelination development. A simple, clever test.

Source: Was an LMP for ten years specializing in injury treatment/ sports massage”