The mammalian brain consists of the cerebrum, the cerebellum and the brain stem. The largest part of the brain is the cerebrum. It consists of the left and right hemispheres that are split down by sagittal fissure. In general, the right hemisphere receives sensations and controls movements of the left body side and the left hemisphere receives sensations and controls movements of the right body side. Behind the cerebrum lies the cerebellum ( the word “ cerebellum” is derived from Latin and means “little brain”). The cerebellum is the centre of the movement control. Although the cerebellum is dwarfed by the cerebrum, it contains so many neurons as both hemispheres combined. In contrast to the cerebrum, the right side of the cerebellum controls movements of the right body side and the left side of the cerebellum controls movements of the left body side. The remaining part of the brain is the brain stem. The brain stem is the stalk from which the cerebrum and cerebellum sprout. The brain stem consists of a nexus of fibers and cells that in part relays information from the cerebrum to the spinal cord and cerebellum and vice versa. Although the brain stem is considered to be the most primitive part of the mammalian brain, it plays the vital role in maintaining life-depending functions such as breathing, being conscious and controlling the body temperature. Therefore, one can survive the damage to the cerebrum and the cerebellum, but the damage to the brain stem is fatal.