Nystagmus or spontaneous oscillatory movements are seldom seen in the position of fixation. It may be horizontal, vertical, rotatory, dissotiated (different in each eye). There are two components, quick and slow. Nystagmus is described as follows: direction of quick component, direction of gaze which produces it, speed, amplitude, and rotatory or linear direction of movement.
Important Features of Cerebellar Pathways
Vestibulo-cerebellar tract
Receives inputs from the vestibular system and visual areas;
Output to vestibular nuclei;
Controls equilibrium (balance) and eye movements;
Spino-cerebellar tract
Is medially placed and it consists of the vermis and the intermediate zones;
Input from spinal interneurons, sensorimotor cortex, auditory, visual and vestibular systems;
Output from the vermis to fastigial nucleus and then to vestibular nucleus and reticular formation in brainstem;
Output from intermediate zone to interposed nucleus and then to red nucleus of brainstem and ventrolateral nucleus of thalamus;
Fastigial nucleus is important in posture and locomotion;
Interposed nucleus acts to control stretch reflexes and other somatosensory reflexes and damp tremor;
Cerebro-cerebellar pathway
?Input from cerebral cortex
Output to dentate nucleus and then to ventrolateral thalamus to motor cortex and premotor cortex
Important for planning and initiation of volitional movement