<prompt> Which of the marked area is involved in relieving pain when painful site is massaged?ABCD  <response>: Ans. A. A Substantia gelatinosaThe gate-control theory of pain postulates that massage may be effective in closing the gate--that is, inhibiting the transmission of noxious stimuli by stimulating large nerve fibers.When pressure fibers are stimulated Ab it inhibits pain fibers via gelatinosa interneurons. The marking area A is substantia gelatinosa. Massage stimulates A-beta fiber, which acts on gelatinosa neuron G neuron of dorsal of spinal cord. G neuron in turn inhibits small diameter pain fiber closing the gate at the spinal cord level. This theory was proposed by Melzack Wall and is also known as gate control theory of pain. 