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The expanded, most complex, and very important anterior part of the CNS, is the brain. It is enclosed within a bony box of the skull called the cranium. The brain is hollow and is protected by the three meanings. The cavities of the brain are called ventricles. The ventricles and the sub-durable space are filled with cerebrospinal fluid. In most parts of the brain, the gray matter areas are found on the surface and the white matter areas deep inside. The brain is divided into three parts. They are, the fore brain, mid brain, and hind brain Fore brain (pros encephalon) The anterior most part of the brain is called the fore brain. The main parts of the fore brain are the cerebrum and the diencephalons. The cerebrum is the largest, most prominent, and most important part of the entire brain. It consists of two large hemispheres called cerebral hemispheres. The two hemispheres are held together and connected by a curved, thick band of nerve fibbers, known as the corpuscallosum. Three deep and wide fissures, divide each cerebral hemispheres into four lobes. They are, an anterior frontal lobe, a dorsal parietal lobe, a posterior occipital lobe, and a lateral temporal lobe. The surface of the cerebral hemispheres show many irregular, convoluted projecting folds called gyri. The gyri are separated from one another, by shallow grooves(depressions) called sulky. The gyri increase the surface area of the cerebral hemisphere so that a very great number of nerve cells can be present here. The peripheral(surface) region of the cerebral hemisphere is formed of gray matter and is called the cerebral cortex. The cerebral cortex is composed of the cytons(cell bodies) of a multitude of neurons(slightly more than half of the ten billion neurons present in the human nervous system). The deeper, inner regions of the cerebral hemispheres are formed of white matter, and is called the cerebral medulla. Myelin Ted nerve fibbers of the neurons are present here. The cerebral cortex is a very important part of the brain, as it possesses numerous nerve centers or nerve areas. These nerve centers control, coordinate and regulate, the nerves system and all other systems of the body. These areas of the cerebral cortex may be broadly classified into three. They are, the sensory areas, motor areas, and association areas. Sensory areas are concerned with the reception and interpretation of the sense of vision, hearing, smell, taste, and the various sensations of the skin such as touch, pressure, pain, etc. The location of sensory areas in the cortex include, visual areas(for vision) in the occipital lobes, auditory(for hearing), olfactory(for smell) and gustatory(for taste) areas in the temporal lobes, and the general sensory or(for taste) areas in the temporal lobes, and the general sensory or soma esthetic area(for skin sensations) in the parietal lobe. The motor areas which control voluntary movements are present in the posterior part of the frontal lobe. This lobe also carries the pre-motor areas which control involuntary movements.