The trigeminal nerve's coresystem comprises four units on either side of the midline and extends throughout the brainstem and down into the upper part of the spinal cord.
The four cores are:
1/ Motor trigeminal nucleus 2/ Mesencephala trigeminal nucleus 3/ Sensory main nucleus of the trigeminal nerve4/ Spinal trigeminal nucleus
Of these, 3/ and 4/ send moss threads to the cerebellum hemisphere of the same side.