Brain stem nuclei giving fibers to lobules VI and VII of the cerebellar vermis.

The HRP method has been used to identify all the brain stem nuclei, which may project to lobule VI and/or VII of the posterior cerebellar vermis. Three tentative degrees of labeling of the different structures have been assigned: 'massive', 'clear' and 'discrete'. (1) Massive projections have been found to reach lobule VI and VII from the inferior olive and lobule VII only from the nucleus reticularis tegmenti pontis. (2) Clear projections have been found to reach lobule VI only from the pontine nuclei, the nucleus reticularis tegmenti pontis, the nucleus reticularis lateralis and the reticularis paramedianus; lobule VII only from the raphe nuclei, and both VI and VII from the perihypoglossal and vestibular nuclei. (3) Discrete projections have been found to reach lobule VI and VII from the deep cerebellar nuclei; lobule VI only from the nucleus tracti solitarii and nucleus cuneatus externus; lobule VII only from the nucleus lemnisci lateralis pars ventralis, the nuclei parabrachiales and the nucleus subcoeruleus.