raphe nuclei, a subgroup of the reticular nuclei of the brainstem found in narrow longitudinal sheets along the raphae of the medulla oblongata, pons, and mesencephalon. They include many neurons that synthesize serotonin. Their ascending fibers project to parts of the limbic system, and their descending fibers project to other brainstem nuclei, the medulla oblongata, and the pons. In the group are the magnus raphe nucleus, median raphe nucleus, obscurus raphe nucleus, pallidal raphe nucleus, pontine raphe nucleus, posterior raphe nucleus, inferior linear nucleus, intermediate linear nucleus, and superior linear nucleus.
