Pain is defined as "an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms that imply such damage". A better understanding of the neurophysiological mechanisms and anatomical bases involved in pain, i.e., the set of body functions that enable the detection, perception and response to potentially nociceptive stimuli, has clearly contributed to improving the management of acute and chronic pain. The nociceptive message is generated at the peripheral level, it is transported by the peripheral nerve fibre and then conveyed into the nerve, thalamic relay with a second neuron and then its integration into the brain structures which transforms it into a conscious message. This message is permanently modulated, this modulation with an inhibitory effect is mainly exerted at the medullary level through intrinsic mechanisms using inhibitory neuromodulators. Anatomophysiological data allow us to classify pain into three types: Excessive nociception pain, neuropathic pain and psychogenic pain.