Raphe Kernels

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Horizontal section through the midbrain, c = mesencephalic raphe nuclei

The raphe nuclei , or nuclei raphes , are a group of nuclei of the central nervous system that are distributed over the entire brain stem . The nuclei lie along the median line at the "seam" of the two halves of the brain stem, hence the name (Greek rhaphé "seam"). The neurotransmitter of the raphe nuclei is serotonin .

The nuclei are involved in the descending system of pain reduction. Their afferents come, among other things, from the central gray cave , the efferents go into many parts of the brain, but functionally most important to the noradrenergic locus caeruleus , which is also located in the brain stem, and to the dorsal horn of the spinal cord , where they excite inhibitory interneurons in the substantia gelatinosa , which in turn inhibit pain fibers (A-delta and C-type) coming from the periphery and thus reduce the sensation of pain.