Myelination of the nervous system follows the cephalocaudalproximodistal laws of development and is closely related to the observed mastery of fine and gross motor skills. Myelin is necessary for rapid and efficient transmission of some, nut not all, nerve impulses along the neural pathway. Tracts that develop myelin earliest are the sensory, cerebellar, and extrapyramidal. This accounts for the acute senses of taste, smell,and hearing, as well as the perception of pain,in the newborn.All cranial nerves are myelinated except the optic and plfactory nerves.