The constituent parts of the cerebral hemispheres are the brain cloak and subcortical ganglia. Surround their lateral ventricles.
Between the right hemisphere and the left is a deep longitudinal groove. In its depths lies the corpus callosum. It is formed by nerve fibers.
The cerebral cortex of the human brain is represented by a brain cloak. This gray matter is formed by nerve cells with processes extending from them and neuroglia cells. It is believed that the latter perform a supporting function for neurons and participate in the metabolism of their substances.
The cerebral cortex is the highest, from the phylogenetic point of view, the youngest formation of the central nervous system. The thickness of its layer is from one and a half to three millimeters. The cerebral cortex has about twelve to eighteen billion neurons.
Its total surface increases due to the presence of numerous furrows. They divide the surface of the hemispheres into lobes and convex gyrus. There are four lobes in each hemisphere. They are formed due to three furrows: lateral, parietal-occipital and central. As a result, the occipital, temporal, parietal and frontal lobes are formed.
The latter is located in front of the central groove. The parietal lobe is limited by the central furrow in front, below - the lateral, parietal-occipital - behind. The temporal lobe is limited by a deep lateral groove at the top. Occipital lobe located posterior to parieto-occipital.
Above the corpus callosum is white matter. It consists of projection, commissural and associative fibers. The cerebral cortex has a two-way connection with the lower parts of the central nervous system through ascending and descending paths. They include projection fibers that extend beyond the hemispheres.
Individual cortical areas have functional different meanings. Along with this, the cerebral cortex works as a whole. However, there is no strict functional localization in it. Experiments on animals showed that after the destruction of individual sections in the cortex, after a certain period of time, neighboring areas began to fulfill the functions of destroyed sections. This feature is associated with high cell plasticity.
The cerebral cortex receives centripetal impulses from receptor formations. For each apparatus of the receptors in it there corresponds a site called I.P. Pavlov "the cortical core of the analyzer." The areas of the cortex in which they are located are called sensory sites.
In the posterior central and anterocentral zones of the cortex, the nuclear region of the motor analyzer is located. Excitation is carried out in it from tendon receptors, skeletal muscles and joints.
The area of the skin analyzer is located behind the central sulcus (in the posterior central zone). It is associated with tactile, pain and temperature sensitivity.
The largest area is occupied by the area of analyzers of the face, voice apparatus, hands. The smallest area is reserved for the representation of the tibia, thigh and trunk analyzers.
In the occipital zone is the nuclear region of the visual analyzer, in the temporal - auditory. The area of taste buds is located near the lateral groove.
The movement occurs as a result of irritation, which is formed from interaction with the sensory areas of the motor zone of the cortex. It is located from the central furrow anteriorly.
The nuclear regions of the analyzers are represented in the cortex by areas in which most of their pathways end. Outside of them are scattered elements. In them, pulses of the same receptors are received that enter the analyzer core.