Neuroanatomical correlates of vestibular function.

Neuroanatomical data revealed by new neuroanatomical techniques over the past decade, have clarified the central connections of the peripheral vestibular sense organs. A knowledge of this information is important in the clinical evaluation of vestibular disorders. The reflex connections of the semicircular canals serve vestibulocerebellar, vestibulo-ocular, commisural, and vestibulospinal pathways. The central connections of the utricular macula are primarily in a descending direction to the motor neurons of the entire length of the spinal cord. These form the basif for vestibulospinal reflexes which are characteristically associated with utricular function. Additional central connections provide the basis for vestibulo-ocular responses to utricular activity. Finally, the saccule has reflex connections both to the upper spinal cord to a minor degree and to extraocular nuclei that serve vertical and oblique eye movements. The minor vestibular group Y nucleus provides a commissural reflex connection for the saccule.