ABSTRACT
The central nervous system (CNS) consists of the brain and the spinal cord. All other nerve cells are part of the peripheral nervous system. The constituent components of the brain are collections of cell bodies that appear gray when looked at under the microscope and fiber tracts that appear white under the microscope. Hence structures in the brain are all discrete regions of gray matter. In humans the brain is folded over at its 'top' end. This means that the brain tissue lying immediately under the forehead is not really at the front but at the top. This strange state of affairs need not cause any problem but it may mean that the relative labels of adjacent parts of the brain are counter-intuitive. The brain can be considered to be divided into its main areas in several ways. Most accurately, the brain can be divided into five regions, the myelencephalon, the metencephalon, the mesencephalon, the diencephalon, and the telencephalon.
