Definition: a large, well-defined, somewhat elongated cell mass, reddish-gray in the fresh brain, located in the rostral mesencephalic tegmentum. This nucleus is composed of a caudal pars magnocellularis [TA] (magnocellular part [TA]), a rostral pars parvocellularis [TA] (parvocellular part [TA]) and a small pars posteromedialis [TA] (posteromedial part [TA], dorsomedial part [TAalt]). The nucleus receives a massive projection from the contralateral half of the cerebellum by way of the superior cerebellar peduncle and an additional projection from the ipsilateral motor cortex. Projections from the anterior interposed nucleus and motor cortex to the red nucleus are somatopically organized. Its efferent connections are with the contralateral rhombencephalic reticular formation and spinal cord by way of the rubrobulbar and rubrospinal tracts. Rubrospinal fibers have somatotopic origin.
Synonym(s): nucleus ruberTA