Fig. 1

Anatomy of the pain pathways. Primary afferent nociceptors convey noxious information to neurons within the spinal dorsal horn of the spinal cord. These neurons project to the thalamus via the spinothalamic pathway and then to somatosensory cortex. This projection provides information about the location and nature of the stimulus (pathway in blue). The affective component is provided by projections to the cingulate and insular cortices via projections in the brainstem (parabrachial nucleus) and amygdala (pathway in orange). Descending inhibitory control pathways (Red line) originating in the PAG and RVM in the brainstem control the output of spinal nociceptive neurons in response to a noxious stimulus. PAG periaqueductal grey, PB parabrachial nucleus, RVM rostroventral medulla, DRG dorsal root ganglia