White matter is nervous tissue composed mainly of myelinated nerve fibers. It makes up the conducting part of the brain and spinal cord. The medulla consists of both white and gray matter. The white matter consists mainly of nerve tracks that pass between the spinal cord and the various portions of the brain. It consists of fibers that connect the two hemispheres of the brain and the fibers that are part of both ascending and descending tracts. Basel gangala are located within the white matter and links the various areas of the brain. White matter of the cerebrum consists of myelinated neurons. There is a large band of white matter, called the corpus callosum, which connects the right and left hemispheres.