Projection to the Spinal Cord from the Medial and Descending Vestibular Nuclei of the Cat

Abstract

THE principal projection from the vestibular nuclei to the spinal cord of the cat is the vestibulospinal tract, which originates in Deiters's nucleus¹, but fibres from the vestibular nuclei also reach the cord through the descending medial longitudinal fasciculus (MLF). There is uncertainty concerning the origin of this bundle: some authors have suggested that some of its fibres originate in the medial and descending nuclei¹, while others believe that the descending nucleus does not contribute to this projection². Many descending MLF fibres may be branches of dichotomizing axons, the other branch of which enters the ascending MLF¹. The descending MLF fibres terminate in parts of lamina VII and lamina VIII of the spinal cord², but their exact connexions and function are not known; impulses in the descending MLF may produce depolarization of primary afferent terminals, perhaps by relays through propriospinal pathways³.