noun, plural: scratch reflexes
(1) A spinal reflex characterized by a response to the activation of sensory neuron wherein the peripheral terminals are near the surface of the body
(2) A reaction to itch or pruritus
Scratch reflex is a spinal reflex that inclines the person or an animal to scratch or rub the affected area. An example is that one in dogs wherein a stimulus applied to the skin of a saddle-shaped area of the back, sides and flanks produces a scratching movement of the hind leg of the side that is stimulated. Another example is when a sensation in the skin that causes to want to scratch or rub particularly when in contact with an irritant, such as an allergen or a chemical. A scratch reflex is a response when the sensory neurons are activated. The sensory neurons are located on the surface of the body.1 The scratch reflex is a response or as a result of the stimulation of neurons producing the itch sensation. Scratching interrupts the activation of these neurons and therefore provides relief to itch or pruritus. It is also used as a means to remove the irritant causing the itchy sensation.
1 Stein, P. S. G. (1983). The Vertebrate Scratch Reflex. Symposia of the Society for Experimental Biology(37), 383-403.