The large (final) brain in the course of evolution appeared later than other departments. Its size and mass are much larger than other segments. The article will present his photo. The human brain is associated with the most complex manifestations of intellectual and mental activity. The body has a fairly complex structure. Next, we consider the structure of the final brain and its tasks.
Structure
The structure of the department includes two large segments. The cerebral hemispheres are connected to each other through the corpus callosum. Between these segments are also commissures: arch, back and front. Considering the structure of the finite brain, attention should be paid to the cavity in this department. They form the lateral ventricles: left and right. Each of them is located in the corresponding segment. One of the walls of the ventricles is formed by a transparent septum.
Segments
The hemisphere is covered by cortex. This is a layer of gray matter, which is formed by neurons of more than 50 species. Under the bark is a white substance. It consists of myelinated fibers. Most of them connect the cortex with other centers and parts of the brain. In the white matter there are accumulations of gray - basal ganglia. Legs and thalamus are grown to the hemispheres of the brain. The delimiting segments from the thalamus of the intermediate department, the layer of white matter is called the inner capsule. The hemispheres are separated by a longitudinal slit. In each segment there are three surfaces - the lower, lateral and medial - and the same number of edges: temporal, occipital and frontal.
Cloak surface
In each segment, this part of the brain is divided into lobes through deep grooves and crevices. Primary refer to the permanent formations of the body. They are formed at the embryonic stage (in the fifth month). The largest cracks include longitudinal (separates segments) and transverse (separates from the occipital lobes of the cerebellum). Secondary and especially tertiary formations determine the individual relief of the segments (it is visible in the photo). The human brain develops not only in the prenatal period. For example, secondary and tertiary grooves form up to 7-8 years after birth. The relief, which has a finite brain, the location of permanent formations and large convolutions in most people are similar. Six lobes are distinguished in each segment: limbic, islet, temporal, occipital, parietal and frontal.
Lateral surface
The terminal brain in this area includes the Roland (central) sulcus. With its help, the parietal and frontal lobes are separated. Also on the surface there is a Sylvian (lateral) groove. Through it, the parietal and frontal lobes are separated from the temporal lobe. The conditional line acts as the front-lower border of the occipital region. It passes from the upper edge of the parieto-occipital sulcus. The line is toward the lower end of the hemisphere. The islet (islet lobe) is covered by areas of the temporal, parietal and frontal areas. It lies in the lateral groove (in depth). Near the corpus callosum, the limbic lobe is located on the medial side. It is separated from other areas by a belt furrow.
Brain: anatomy. Frontal lobe
It contains the following elements:
- Precentral groove. The gyrus of the same name is located between it and the central recess.
- Frontal grooves (lower and upper). The first is divided into three zones: orbital (orbital), triangular (triangular), opercular (tympanic). Between the depressions lie the frontal gyrus: upper, lower and middle.
- Horizontal front furrow and ascending branch.
- Frontal medial gyrus. It is separated from the limbic fissure.
- Section of the cingulate gyrus.
- Orbital and olfactory grooves. They are located on the underside in the frontal lobe. The elements of the same name lie in the olfactory sulcus: bulb, triangle and tract.
- Straight gyrus. It passes between the medial end of the hemisphere and the olfactory groove.
The anterior horn in the lateral ventricle corresponds to the frontal lobe.
Tasks of cortical zones
Considering the final brain, structure and functions of this organ, it is necessary to dwell in more detail on the activity of the departments of the frontal lobe:
- Anterior central gyrus. There is a cortical core from the motor analyzer, or kinesthetic center. A certain amount of afferent fibers from the thalamus enters this zone. They carry proprioceptive information from joints and muscles. In this area, descending paths to the spinal cord and trunk begin. They provide the possibility of conscious regulation of movements. If the final brain is damaged in this area, then paralysis of the opposite side of the body occurs.
- The posterior third is in the frontal middle gyrus. Here is the center of graphics (letters) and the associative zone of signs.
- The posterior third of the frontal inferior gyrus. In this area there is a speech-motor center.
- The middle and anterior third of the middle, upper and partially lower frontal gyrus. In this area lies the associative anterior cortical zone. She carries out programming of various complex behavioral forms. The area of the medial frontal gyrus and frontal pole is associated with the regulation of the emotiogenic areas included in the limbic system. This area refers to the control of the psycho-emotional background.
- Anterior frontal mean gyrus. Here is a zone of combined rotation of the eyes and head.
Parietal lobe
The middle region of the lateral ventricle corresponds to it . The terminal brain in this area includes the postcentral gyrus and groove, parietal lobes - the upper and lower. Behind the parietal lobe passes the wedge. The structure also has an inter-dark furrow. In the lower region there are convolutions - angular and supra marginal, as well as a section of the paracentral lobule.
Tasks of the cortical zones in the parietal lobe
Describing the final brain, structure and functions of this structure, one should distinguish such centers as:
- Projection Department of General Sensitivity. This center is a skin analyzer and is represented by the cortex of the postcentral gyrus.
- The projection section of the body diagram. It corresponds to the edge of the intrathoracic groove.
- Associative department of "stereognosy". It is represented by the core of the analyzer (dermal) recognition of objects when palpating. This center corresponds to the cortex of the parietal superior lobule.
- Associative department of praxia. This center performs the tasks of analyzing habitual purposeful movements. It corresponds to the cortex of the supra marginal gyrus.
- The associative optical speech department is a writing analyzer - the center of lexia. This zone corresponds to the cortex of the angular gyrus.
Brain: anatomy. Temporal lobe
On its lateral side there are two furrows: the lower and upper. They, together with the lateral, limit gyrus. On the lower surface of the temporal lobe, there is no clear border separating it from the back. Near the lingual gyrus is the occipital-temporal. From above, it is bounded by a collateral groove of the limbic region, and laterally by the temporal occipital. The proportion corresponds to the lower horn of the lateral ventricle.
The tasks of the cortical zones in the temporal section
- In the middle section of the superior gyrus, on its upper side, is the cortical part of the auditory analyzer. The posterior third of the gyrus includes the auditory area of speech. When injuring this area, the speaker's words are perceived as noise.
- The lower and middle region of the convolutions contains the cortical center of the vestibular analyzer. If the functions of the final brain are impaired here, the ability to maintain balance when standing is lost, and the sensitivity of the vestibular apparatus decreases.
Island
This lobe is located in the lateral and is limited by a circular furrow. Presumably in this area, brain functions are manifested in the analysis of taste and olfactory sensations. In addition, the area’s tasks probably include auditory perception of speech and processing of somatosensory information.
Limbic lobe
This area is located on the medial surface of the hemispheres. It consists of a waist, para-hippocampal and dentate gyrus, isthmus. The furrow of the corpus callosum acts as one of the boundaries of the lobe. She, descending, goes into the deepening of the hippocampus. Under this furrow, in turn, in the lower horn cavity of the lateral ventricle is a gyrus. Above the recess in the corpus callosum lies another border. This line - the cingulate sulcus - separates the cingulate gyrus, delimits the parietal and frontal lobes from the limbic. With the help of the isthmus, the cingulate gyrus passes into the para-hippocampal. The latter ends with a crochet.
Department Tasks
Paragippocampal and cingulate gyrus are directly related to the limbic system. Brain functions in this area are associated with the control of a complex of psychoemotional, behavioral and autonomic reactions to environmental stimuli. The parahippocampal zone and hook include the cortical region of the olfactory and gustatory analyzer. At the same time, the hippocampus is associated with learning abilities; it determines the mechanisms of long-term and short-term memory.
Occipital region
A transverse furrow runs on its lateral side. In the medial part there is a wedge. On the back, it is bound by a spur, and in front, by the parieto-occipital sulcus. Also on the medial site is a lingual gyrus. Above, it is limited by spur, and below - by a collateral groove. The occipital lobe corresponds to the horn in the lateral ventricle.
Departments of the occipital region
In this zone, such centers are distinguished as:
- Projection visual. This segment is located in the cortex, which borders the spur furrow.
- Associative visual. The center is located in the cortex of the dorsal site.
White matter
It is presented in the form of numerous fibers. They are divided into three groups:
- Projection . This category is represented by bundles of efferent and afferent fibers. Through them, there are connections between the projection centers and the basal, stem and spinal nuclei.
- Associative . These fibers provide the connection of cortical areas within the boundaries of one hemisphere. They are divided into short and long.
- Commissural . These elements connect the cortical zones of the opposite hemispheres. Commissural formations are: corpus callosum, posterior and anterior commissure, and arch commissure.
Bark
Its main part is represented by the neocortex. This is the “new cortex,” which is phylogenetically the latest brain formation. Neocortex occupies about 95.9% of the surface. The rest of the brain is presented as:
- Old bark - Archiocortex. It is located in the temporal lobe and is called the amon horn, or the hippocampus.
- Ancient bark - paleocortex. This formation occupies a site in the frontal lobe next to the olfactory bulbs.
- Mesocortex . These are small areas adjacent to the paleocortex.
Old and ancient bark appear in vertebrates earlier than others. These formations are distinguished by a relatively primitive internal structure.