The cerebellum receives sensations at unconscious level. The inputs are derived from the vestibular system, stretch receptors of muscle spindle and Golgi tendon organs, tactile and pressure receptors of the head and body, and sensations from the visual and auditory system.
It uses these inputs for maintaining equilibrium, muscle tone, and posture and adjusts coordination of skilful volitional movements by regulating the relative muscle tension of agonist and antagonist muscles. The cerebellum has been called the head ganglion of the proprioceptive system.
(1) The anterior lobe of the cerebellum acts like a mode-changing switch, making muscles contract either in the a-led mode or y-led mode.
(2) The vermal cerebellum and flocculonodular lobe are mainly concerned with body equilibrium.
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(3) The paravermal regions regulate locomotion and movements of exploratory nature.
(4) The hemispheric regions supervise skilful learned movements.
(5) The cerebellum coordinates the rhythmic action of agonist and antagonist muscles, as in diadochokinesia. It is also important in motor learning and conditioning.
(6) The cerebellum also influences autonomic functions through the hypothalamus and reticular formation. Stimulation of the anterior lobe produces sympathetic response while stimulation of tonsils produces parasympathetic response.