Control of movement is largely determined by incoming (afferent) and outgoing (efferent) neural impulses in the cerebellum.
Motor information input travels from the spinal cord, cerebral cortex and vestibular system via mossy fibers.
Feedback regarding movements returns to the cerebellum via the inferior olivary nucleus in the medulla oblongata. This feedback loop allows the brain to coordinate movement.
All outgoing neural impulses from the cerebellum travel via the deep cerebellar and vestibular nuclei. Proper functioning of the neuronal pathway between mossy fibers, granular cells, parallel fibers, climbing fibers and Purkinje cells are thought to be essential for coordinated muscular movement. Glutamate is a neurotransmitter in the excitatory synapses between climbing fibers and Purkinje cells as well as between granular cells and mossy fibers. Disruptions in this system are thought to be involved in a variety of movement disorders.