Vestibulocerebellar Input in the Cat: Anatomy

Abstract

According to recent studies, the primary vestibularfibres terminate in the nodulus, the adjoining ventral folia of the uvula, the paraflocculus, and the ventral paraflocculus. Within the intracerebellar nuclei, terminations have been established in the small-celled ventral part of the lateral (dentate) nucleus, but a termination in the fastigial nucleus is still conjectural. According to anatomical data, primary vestibular fibers ending in the cerebellum are derived from the semicircular ducts. The primary vestibular fibers end as mossy fibers. These appear to differ in certain respects from the classical type. Secondary vestibular fibers take origin from restricted parts of the vestibular complex only: the group x and the ventrolateral part of the descending vestibular nucleus with a few fibers from the ventral part of the medial nucleus. The fibers appear to terminate in the same regions, as do the primary vestibular fibers. The regions of the vestibular nuclei, which give off secondary vestibular fibers receive few or no primary vestibular afferents. A main source of afferents to these regions is the spinal cord. Accordingly, the secondary vestibular fibers appear to be linked in a spinocerebellar pathway ending in the vestibulocerebellum. Vestibular impulses may reach the cerebellum via other routes.