A pale pink structure consisting of a large group of cells located in the ventral medial mesencephalon. Together with the substantia nigra, it forms sub-cortical ‘hotspots’ of the extrapyramidal system. It receives inputs from the cerebellar nuclei and cerebral cortex, and projects the ipsilateral inferior olive by means of the central tegemental tract and the contralateral spinal cord via the rubropspinal tract. It forms a functional distinction between other primates (including humans) and mammals. In primates, motor control and coordination mainly involve the corticospinal tract in contrast with other mammals where the rubrospinal tract is more dominant in these respects (especially with regard to gait), and thus it has a limited role in the control and coordination of the hands. Nevertheless, crawling in human infants is controlled via the red nucleus. Lesions to red nucleus have serious functional consequences such as choreoathetosis (irregular twisting and writhing movements), contralateral cerebellar ataxia, abnormal muscle tone, and resting tremors (e.g., in Parkinson’s disease).
See Basal ganglia (anatomy), Deep cerebellar nuclei, Corticospinal tracts, Extrapyramidal system, Inferior olive (or olivary) nucleus, Mesencephalon, Metacephalon, Muscle tune (or power), Parkinson’s disease, Rubrospinal tract