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 feature his photo. The human brain is associated with the most complex manifestations of intellectual and mental activity. The body has a rather complex structure. Next, consider the structure of the telencephalon and its tasks.
Structure
The department in question includes two large segments. The cerebral hemispheres are connected to each other through the corpus callosum. There are also adhesions between these segments: fornix, posterior and anterior. Considering the structure of the telencephalon, one should pay attention to the cavities in this section. 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 hemispheres are covered by the bark. This is a layer of gray matter, which is formed by more than 50 types of neurons. Under the bark is white matter. It is made up of myelinated fibers. Most of them connect the cortex with other centers and parts of the brain. in white matterthere are accumulations of gray - the basal ganglia. The legs and thalamus are attached to the hemispheres of the brain. The layer of white matter that separates the segments from the thalamus of the intermediate section is called the internal capsule. The hemispheres are separated from each other by a longitudinal fissure. Each segment has three surfaces - inferior, lateral and medial - and the same number of edges: temporal, occipital and frontal.
Surface of the raincoat element
In each segment, this part of the brain is divided into lobes by means of deep furrows and fissures. Primary refers to the permanent formations of the body. They are formed at the embryonic stage (in the fifth month). The largest fissures include longitudinal (separates the segments) and transverse (separates the cerebellum from the occipital lobes). Secondary and, in particular, tertiary formations determine the individual relief of the segments (it can be seen in the photo). The human brain develops not only in the prenatal period. For example, secondary and tertiary furrows are formed up to 7-8 years after birth. The relief that the telencephalon has, the location of permanent formations and large convolutions in most people are similar. Six lobes are distinguished in each segment: limbic, insular, temporal, occipital, parietal and frontal.
Lateral surface
The telencephalon in this area includes Roland's (central) sulcus. With its help, the parietal and frontal lobes are separated. Also on the surface there is a Sylvian (lateral) furrow. Through it, the parietal and frontal lobes are separatedfrom the temporal. An imaginary line acts as the anteroinferior border of the occipital region. It runs from the upper edge of the parieto-occipital sulcus. The line is directed towards the lower end of the hemisphere. The islet (islet lobe) is covered by areas of the temporal, parietal and frontal regions. It lies in the lateral furrow (in depth). Next to the corpus callosum on the medial side is the limbic lobe. It is separated from other areas by means of a girdle furrow.
Brain: Anatomy. Frontal lobe
It contains the following elements:
- Precentral sulcus. The gyrus of the same name is located between it and the central depression.
- Frontal furrows (lower and upper). The first is divided into three zones: orbital (orbital), triangular (triangular), opercular (cover). Between the recesses lie the frontal gyrus: upper, lower and middle.
- Horizontal anterior sulcus and ascending branch.
- Frontal medial gyrus. It is separated from the limbic cingulate groove.
- Area of the cingulate gyrus.
- Orbital and olfactory furrows. They are on the underside in the frontal lobe. The olfactory groove contains elements of the same name: bulb, triangle and tract.
- Direct gyrus. It runs between the medial end of the hemisphere and the olfactory groove.
The anterior horn in the lateral ventricle corresponds to the frontal lobe.
Problems of cortical zones
Considering the telencephalon, the structure and functions of this organ, more details are neededdwell on the activity of the departments of the frontal lobe:
- Anterocentral gyrus. Here there is a cortical nucleus from the motor analyzer, or a 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 telencephalon is damaged in this area, then paralysis occurs on the opposite side of the body.
- Posterior third in the frontal middle gyrus. Here is the center of graphics (letters) and the associative zone of signs.
- Posterior third of the frontal inferior gyrus. In this area is the speech-motor center.
- The middle and anterior third of the middle, superior and partially inferior frontal gyrus. The associative anterior cortical zone lies in this area. It performs programming of various complex behavioral forms. The zone of the medial frontal gyrus and the frontal pole are associated with the regulation of the emotiogenic areas included in the limbic system. This area refers to the control over the psycho-emotional background.
- Anterior frontal middle gyrus. Here is the zone of combined rotation of the eyes and head.
Parietal lobe
It corresponds to the median region of the lateral ventricle. The telencephalon in this area includes the postcentral gyrus and sulcus, the parietal lobules - the upper and lower. Behind the parietal lobe is the precuneus. ATthe structure also contains an interparietal sulcus. In the lower region there are convolutions - angular and supramarginal, as well as a section of the paracentral lobule.
Problems of the cortical zones in the parietal lobe
Describing the telencephalon, the structure and functions of this structure, one should single out such centers as:
- Projection department of general sensitivity. This center is a skin analyzer and is represented by the cortex of the postcentral gyrus.
- Projection section of the body diagram. It corresponds to the edge of the intraparietal sulcus.
- Associative department of "stereognosia". It is represented by the core of the analyzer (skin) recognition of objects during palpation. This center corresponds to the cortex of the parietal superior lobule.
- Associative Department "praxia". This center performs the tasks of analyzing habitual purposeful movements. It corresponds to the cortex of the supramarginal gyrus.
- The associative optical department of speech is a writing analyzer - the center of the lexicon. This zone corresponds to the cortex of the angular gyrus.
Brain: Anatomy. Temporal lobe
On its lateral side there are two furrows: lower and upper. They, together with the lateral, limit the gyrus. On the lower surface of the temporal lobe, there is no clear boundary separating it from the back. Near the lingual gyrus is the occipital-temporal. From above, it is limited by the collateral groove of the limbic region, and laterally by the temporal occipital. The lobe corresponds to the inferior horn of the lateral ventricle.
Tasks of the cortical zones in the temporal region
- In the middle section of the superior gyrus, on its upper side, there is a cortical section of the auditory analyzer. The posterior third of the gyrus includes the auditory zone of speech. When this area is injured, 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 telencephalon are disturbed here, the ability to maintain balance when standing will be lost, the sensitivity of the vestibular apparatus will decrease.
Islet
This lobe is located in the lateral and is limited by the circular furrow. Presumably in this area, brain functions are manifested in the analysis of taste and smell sensations. In addition, the tasks of the area are likely to include auditory speech perception and somatosensory information processing.
Limbic lobe
This area is located on the medial surface of the hemispheres. It consists of the cingulate, parahippocampal and dentate gyrus, isthmus. The sulcus of the corpus callosum acts as one of the boundaries of the lobe. She, descending, passes into the deepening of the hippocampus. Under this groove, in turn, in the lower horn cavity of the lateral ventricle is a gyrus. Above from the depression 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 parahippocampal. The last one ends with a crochet.
Department Tasks
The parahippocampal and cingulate gyrus are directly related to the limbic system. The functions of the brain in this area are associated with the control of a complex of psycho-emotional, behavioral and vegetative reactions to environmental stimuli. The parahippocampal zone and the hook include the cortical region of the olfactory and gustatory analyzers. At the same time, the hippocampus is associated with learning abilities, it determines the mechanisms of long-term and short-term memory.
Occipital region
There is a transverse furrow on its lateral side. There is a wedge in the medial part. Behind it is limited by the spur, and in front by the parietal-occipital groove. The lingual gyrus also stands out in the medial area. From above, it is limited by the spur, and below - by the collateral groove. The occipital lobe corresponds to the posterior 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 limits the spur groove.
- Associative visual. The center is located in the dorsal cortex.
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 a connection between the cortical regions within the boundariesone hemisphere. They are divided into short and long.
- Commissural. These elements connect the cortical zones of opposite hemispheres. Commissural formations are: corpus callosum, posterior and anterior commissure and commissure of the fornix.
Kora
Its main part is represented by the neocortex. This is the "new cortex", which phylogenetically is the latest brain formation. The neocortex occupies about 95.9% of the surface. The rest of the brain is represented as:
- Old cortex - archiocortex. It is located in the region of the temporal lobe and is called the amon horn, or hippocampus.
- Ancient crust - paleocortex. This formation occupies an area in the frontal lobe near the olfactory bulbs.
- Mesocortex. These are small areas adjacent to the paleocortex.
Old and ancient bark appear in vertebrates before others. These formations are distinguished by a relatively primitive internal structure.
