2021 Volume 38 Issue 2 Pages 133-140
The horizontal component of vestibular eye movements is derived from the lateral semicircular canal, vestibular nucleus, and contralateral abducens nucleus pathway. The vestibular pathway moves the eyes away from the vestibular nucleus. Since this pathway is suppressed by the cerebellum, ipsilateral and contralateral eye deviations can occur in the central lesion. The torsional component is derived from the anterior and posterior semicircular canals, vestibular nucleus, and trochlear or oculomotor nucleus pathways. This vestibular pathway rotates the eyes in a direction opposite to the vestibular nucleus. Since the pathway is crossed, both ipsilateral and contralateral eye rotations can occur in the central lesion. The upward component is derived from the anterior semicircular canal, and the downward component is derived from the posterior semicircular canal; the posterior semicircular canal pathway is not suppressed by the cerebellum, unlike other semicircular canal pathways. Partial damage to the vertical eye-movement pathway causes upward or downward eye deviation.
