Scratch reflex

The scratch reflex is a reflex transmitted by very sensitive nerve endings near the surface of the skin via the spinal cord, and is a reflex frequently inherited by mammals. The nerve signal includes positioning to pinpoint the location of the itch, and the effect of the reflex is either an affective sensation or even an involuntary action to make a scratching movement that usually relieves the itch. The scratch reflex is a reflex to help an organism protect and rid its body of parasites and other irritants.

In case of intense itch, scratching to relieve it can cause pain, and such pain signals are believed to suppress the itch signals due to a lateral inhibition effect, as the dorsal column system transmits critical sensations much faster than the cruder spinothalamic tract that deals with less accurate types of sensations, such as itch, also at a slower pace.