The white matter within the central nervous system is located in different areas. At the cerebral and cerebellum levels, its distribution shows similarity: where we can see a peripheral zone and central area, limited by cortical gray matter and deep basal nuclei. At the level of the brain stem, the white matter is located predominantly in its anterior portions (base of the cerebral peduncle, base of the pons and the bulb pyramid) compared to a smaller proportion of fibers, in the texture that we have seen in the tectum and tegmentum, respectively. At the level of the spinal cord, the white matter is located in the peripheral portion, forming tracts and fascicles inside the spinal cords.