The main reason why you don’t feel itchy when you scratch your armpit is because we know that this action is about to happen, and the brain can pre-regulate the sensation of nerve endings to reduce or eliminate the itch. This phenomenon is known in psychology as “anticipatory inhibition”.

When you try to scratch your armpits, your brain knows that it’s your own action and not an external stimulus by receiving and interpreting signals from your spinal cord and motor neurons. The brain inhibits the transmission of itching signals from the spinal cord to the sensory centers of the brain, thus preventing itching, and in simple terms, when you know that you are about to scratch your armpits, your brain tells the corresponding nerves: “Oh, this is your own scratch, not someone else’s scratch, so you don’t need to itch.” ”

In addition, scratching the armpit may not itch because the action does not really touch that particularly sensitive area, or because we are already very familiar with our body, so we do not feel itchy.

In general, scratching our armpits without itching is mainly because our bodies and brains already have the expected cognition and regulation of this action.