Pain by massaging & liniments is relieved due to -

Ans. is 'a' i.e., Gate control Dorsal horn gating (Gate control theory):o Substantia gelatinosa (SG) in dorsal horn of spinal cord contains enkephalinergic inhibitory interneurons that inhibit, presynaptically as well postsynaptically, the nociceptive spinothalamic neurons. The tactile (touch- pressure) large myelinated Ab fibers of dorsal root stimulate these interneurons through collaterals and thereby inhibit the conduction of pain by spinothalamic tract. The nociceptor Ad and C fibers themselves inhibit these SG inhibitory intemeurons by collaterals and thereby able to transmitt the pain. However, this is only possible if Ab fibers are not stimulated simultaneously.o In other words, SG inhibitor intemeurons serve as a gate in the pain pathway. The gate remains open when only Ad and C fibers are stimulated but tends to close down when Ab fibers are stimulated simultaneouslyo The gate control theory provides the basis for reducing pain by other tactile stimuli. For example, application of counterirritant balm or liniments; massage; transcutaneous electric stimulation (TENS), stimulation of skin e.g. applying hot water bag over an area of visceral stimulation; or acupuncture etc.