Download The expanded, most complex, and very important anterior part of the

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.