hemispheres (Figure 10)
First-order fissures divide each hemisphere into lobes. Lateral (Sylvian) fissure separates the temporal and parietal lobes. Central (Rolandic) sulcus separates the frontal and parietal lobes. Occipitoparietal sulcus separates the occipital and parietal lobes. Second-order sulci divide each lobe of the hemisphere into convolutions.
Frontal lobe. It has precentral, superior and inferior sulci and, accordingly, the anterior central, superior, middle and inferior frontal gyri. In addition, there are branches of the lateral sulcus - anterior and ascending, which divide the inferior frontal gyrus into orbital , triangular And tire parts .
Parietal lobe. It has postcentral, interparietal sulci and, accordingly, the posterior central, superior and inferior parietal gyri. The part of the inferior parietal gyrus that runs around the lateral sulcus is called supramarginal gyrus , the other part goes around the superior temporal, called surangular gyrus .
Temporal lobe. It has superior and inferior sulci and, accordingly, superior, middle and inferior temporal gyri.
Occipital lobe. The main groove is transverse (calcarine).
Island. It is located under the lateral groove and has the shape of a triangle (Figure 13).
Furrows and convolutions of the mediobasal surface of the hemisphere(Figures 11, 12)
Figure 11. Medial surface of the right hemisphere of the brain: 1 - paracentral lobule; 2 - precuneus; 3 - occipital-parietal groove; 4 - wedge; 5 - hippocampal gyrus (parahippocampal); 6 - hook; 7 - cingulate gyrus; 8 - transverse (calcarine groove); 9 - corpus callosum
Olfactory brain(Figures 11, 12). Consists of peripheral and central sections. Peripheral - olfactory bulbs, tracts, triangles and anterior perforated substance. Central part - convolutions of Ammonovarog (hippocampus, seahorse), dentate, vaulted gyrus and uncus. The olfactory brain is part of the limbic system.
Figure 12. Lower surface of the brain: 1 - mastoid bodies; 2 - olfactory bulbs; 3 - olfactory tracts; 4 - olfactory triangles; 5 - anterior perforated space; 6 - hippocampal gyrus; 7 - hook; 8 - occipitotemporal lateral (piriform) gyrus; 9 - occipitotemporal medial (lingual) gyrus
Lateral ventricles of the brain(Figure 13). Found in each hemisphere. In the left - the first, in the right - the second. Their parts form the anterior, inferior and posterior horns.
Basal ganglia of the hemispheres(Figure 13). Cluster gray matter in its thickness or “subcortex”. Form the striatal system ( striatum ) and the globus pallidus system ( pallidum ).
In addition to these nuclei, the basal ganglia include fence And amygdaloid nuclei . Each of these nuclei has its own specific functions.
Caudate nuclei. Regulate the transition from one type of movement to another.
Shell. Pair education. Organizes motor activity, participates in the organization of eating behavior and in its integration with the functions of respiration and salivation.
Figure 13. Cerebral hemispheres on different levels horizontal section (on the right - below the bottom level lateral ventricle, left - above the bottom of the lateral ventricle): 1 - caudate nucleus; 2 - shell; 3 - pale balls; 4 - red kernels; 5 - subthalamic body of Lewis; 6 - fence; 7 - amygdala nucleus; 8 - superior cerebellar peduncles; 9 - middle cerebellar peduncles; 10 - lower cerebellar peduncles; 11 - upper cerebral velum; 12 - cerebellum; 13 - diamond-shaped fossa; 14 - internal capsule; 15 - thalamus; 16 - islet cortex; 17 - lower horn; 18 - brain stripes; 19 - front horn
Pale balls. They regulate the launch or inclusion of an orienting reaction, limb movements and eating behavior (chewing, swallowing).
Fence. Pair education. Participates in excitatory reactions to somatic, auditory, visual stimuli (indicative reactions, turning the head, chewing, swallowing, gagging movements).
Amygdala nucleus. Pair education. Located deep in the temporal lobe. Participates in defensive, autonomic, motor and emotional reactions. The striopallidal system is part of the extrapyramidal system.
(page 7 of 31)Anterior to the optic chiasm is the lamina terminalis, lamina terminalis, which is located in the frontal plane and is a continuation of the ventral end of the corpus callosum. It ends at the base of the genu corpus callosum.
The ventricular surface of the hypothalamus has two depressions along the median plane. The anterior one is located between the optic chiasm and the terminal plate - the supraoptic recess, recessus supraopticus. The second recess corresponds to the funnel - the recess of the funnel, recessus infundibuli.
Finite brain, telencephalon, is a derivative of the anterior cerebral bladder and is represented by two hemispheres big brain, hemispheria cerebrales. In each hemisphere there are:
1) cloak, pallium, formed from the dorsal wall of the medullary bladder;
2) basal ganglia, nuclei basales, developing from its ventral section.
Inside each hemisphere there is a cavity - the lateral ventricle, ventriculus lateralis.
Outer layer raincoat is the cerebral cortex, cortex cerebri, under which is located the white matter, which makes up the largest part of the hemisphere. Functionally, the telencephalon contains higher integration centers responsible for conscious sensitivity, voluntary movements, thinking ability and memory.
Basal ganglia, nuclei basales, are a group of nuclei located at the base of each hemisphere. The entire group of basal ganglia constitutes a mass of gray matter that is generally ovoid in shape.
The basal ganglia includes: the caudate nucleus, nucleus caudatus; lenticular nucleus, nucleus lentiformis; fence, claustrum, and the amygdala, corpus amygdaloideum.
The caudate nucleus has the shape of a comma, located in the sagittal plane, with a longitudinally oriented long axis. It is located lateral and superior to the thalamus. The anterior end of the caudate nucleus is the head, caput, has a thickening. Gradually decreasing in volume, the head of the nucleus continues into the body, corpus, the free surface of which protrudes into the cavity of the lateral ventricle. The body of the caudate nucleus, gradually thinning and bending downwards, continues into the tail, cauda. The caudate nucleus, with its bend, covers the fibers of the white matter, partially extending from the cerebral peduncles. The size of the caudate nucleus in the sagittal direction reaches 6–7 cm. The greatest width in the head region is 20 mm, and in the tail region it is approximately 3 mm.
Lateral to the caudate nucleus and the thalamus thalamus there is a well-defined strip of white matter - the internal capsule, capsule interna, the width of which is 5 – 7 mm. The internal capsule separates the caudate nucleus from the lenticular nucleus. Lenticular nucleus nucleus lentiformis, is surrounded on all sides by white matter and has a wedge-shaped shape in all planes.
It has two parts – lateral and medial. The lateral part, larger in size, is called the shell, putamen; medial part - globus pallidus, globus pallidus.
Shell, putamen, like the caudate nucleus, has a gray-pink color. pale ball, globus pallidus, on a fresh preparation differs in its yellowish color. A thin layer of white matter - the medullary plate, lamina medullaris, separates the shell from the globus pallidus.
Fence, сlaustrum, is located lateral to the shell and is separated from it by a layer of white matter, representing the outer capsule, capsule externa. Even more lateral is a strip of white matter - the outermost capsule, capsule extrema, separating the fence from the island’s crust. The fence on a horizontal section of the hemisphere has the appearance of a thin strip of gray matter (on average 1 - 2 mm). Its outer surface has jagged contours corresponding to the convolutions of the insular cortex. Towards the top and bottom, the fence becomes thinner and moves closer to the amygdala. In a three-dimensional image, it has the appearance of a disk located in the sagittal plane.
amygdala, corpus amygdaloideum, in shape and size (about 10 mm) resembles an almond seed. It is located in the thickness of the white matter of the pole of the temporal lobe. The amygdala with its upper surface acts as an elevation in the anterior section of the lower horn of the lateral ventricle. It is divided into a number of secondary nuclei by thin plates of white matter.
Cerebral cortex It is a layer of gray matter, the thickness of which varies in different sections and averages 2–3 mm. In an adult, due to the final formation of the grooves, the area of the cerebral hemispheres averages 1550 cm2. The surface of the cortex has a complex topography, characterized by numerous grooves, sulci cerebri, and the elevations located between them - convolutions, gyri cerebri. The convolutions differ from each other in shape and size. There is pronounced individual variability in the relief of the cerebral cortex, however, the sulci and gyri of the same name are fundamentally similar in different people and are localized in certain places.
The founder of studies of the cellular composition of the cerebral cortex, the features of the structure and distribution of nerve cells (cytoarchitecture of the cortex) is Kyiv University professor V. A. Betz. Subsequently, in the cerebral cortex, Korbinian Brodmann identified 52 fields, designating each of them with a specific number. The same numbering of fields is preserved in the cytoarchitectonic map compiled by the Russian Brain Institute, but on it a number of fields are divided into zones designated by letters of the Latin alphabet.
In each hemisphere of the cerebrum, there are superior lateral, medial and inferior surfaces. The superior lateral surface of the hemispheres is the most extensive, has a convex shape, facing upward and laterally. It borders the medial surface with a clearly defined edge. The flat medial surface faces the longitudinal fissure of the brain, , in the middle part is connected by the corpus callosum with the same surface of the other hemisphere. The lower surface is flattened in the anterior section, and concave in the posterior section. Three main sulci divide each hemisphere into four lobes, lobi cerebri.
1. Lateral (side) groove, sulcus lateralis, begins on the lower surface of the hemisphere in the form of the lateral (Sylvian) fossa of the cerebrum, fossa lateralis cerebri (Sylvii), runs along the lateral side up and back. It is the anterior superior border of the temporal lobe, lobus temporalis, and separates the frontal and parietal lobes from the temporal lobe.
2. Central sulcus, sulcus centralis (Rolandi), runs along the superolateral surface of the hemisphere, starting from its upper edge. Usually it passes to its medial side and the lower part does not reach the lateral groove. The central sulcus divides top part hemisphere to the anterior section, including frontal lobe, lobus frontalis, and posterior, including the parietal lobe, lobus parietalis, and occipital lobe, lobus occipitalis. Characteristic feature The central sulcus is its continuity throughout.
3. Parieto-occipital sulcus, sulcus parietooccipitalis, is located in the back of the brain on the medial surface of the hemisphere, continuing slightly to the superolateral surface. This groove is the boundary between the parietal and occipital lobes.
In addition to the main four lobes, there is also an insula, insula (Reilli), which is also called the insula, lobus insularis. It lies deep in the lateral sulcus and is visible only when moving apart the convolutions that limit this sulcus.
Furrows and convolutions of the superolateral surface of the cerebral hemispheres(Fig. 16). Frontal lobe, lobus frontalis. On the superolateral surface, anterior to the central sulcus are the superior precentral sulcus and the inferior precentral sulcus. More often they merge into one precentral sulcus, sulcus precentralis. From this groove originate, moving forward, two frontal grooves: the superior, sulcus frontalis superior, and lower, sulcus frontalis inferior.
These grooves divide the surface of the frontal lobe into convolutions. Anterior to the central sulcus is the precentral gyrus, gyrus precentralis. In the remaining area, three frontal gyri stand out:
- superior frontal gyrus, gyrus frontalis superior, which is located above sulcus frontalis superior along the upper edge of the hemisphere;
- middle frontal gyrus, gyrus frontalis medius, which lies between the superior and inferior frontal sulci;
- inferior frontal gyrus, gyrus frontalis inferior, is between sulcus frontalis inferior And sulcus lateralis.
Parietal lobe, lobus parietalis. On the superolateral surface, parallel to the central sulcus, there is a postcentral sulcus, sulcus postcentralis. A long intraparietal sulcus begins from it in the sagittal direction, sulcus intraparietalis. These two grooves divide the surface of the parietal lobe into three sections. Between the central and postcentral sulci is the postcentral gyrus, gyrus postcentralis. Upwards it continues to the medial surface of the hemisphere. The area of the cortex located above sulcus intraparietalis, called the superior parietal lobule, lobulus parietalis superior. The underlying region is the inferior parietal lobule, lobulus parietalis inferior. It contains two very important gyri: supramarginal, gyrus supramarginalis, surrounding the rear end sulcus lateralis, and corner, gyrus angularis, closing the end sulcus temporalis superior.
Rice. 16. Relief of the superolateral surface of the cerebral hemispheres:
1 – sulcus precentralis; 2 – sulcus centralis; 3 – sulcus postcentralis; 4 – sulcus intraparietalis; 5 – sulcus parietooccipitalis; 6 – gyri occipitales superiores; 7 – sulcus occipitalis transversus; 8 – gyri occipitales laterales; 9 – sulcus temporalis inferior; 10 – sulcus temporalis superior; 11 – fossa lateralis cerebri (Sylvii); 12 – sulcus frontalis inferior; 13 – sulcus frontalis superior
Occipital lobe, lobus occipitalis, is the smallest of all shares. On the superolateral surface its grooves vary greatly. Here the semilunar sulcus is distinguished, sulcus lunatus, transverse occipital sulcus, sulcus occipitalis transversus, as well as the preoccipital notch, incisura preoccipitalis, delimiting this lobe from below from the temporal one. Conventionally, on the superolateral surface one can distinguish the superior and lateral occipital gyri, gyri occipitales superiores et laterales.
Temporal lobe, lobus temporalis. The superior temporal sulcus runs on the superolateral surface in the anteroposterior direction, sulcus temporalis superior, which with its posterior end extends into the region of the parietal lobe. inferior temporal sulcus, sulcus temporalis inferior, is better visible from the bottom surface.
Rice. 17. Relief of the medial surface of the cerebral hemispheres:
1 – sulcus corporis callosi; 2 – sulcus cinguli; 3 – sulcus paracentralis; 4 – ramus marginalis; 5 – sulcus parietooccipitalis; 6 – sulcus subparietalis; 7 – sulcus calcarinus; 8 – polus occipitalis; 9 – sulcus hippocampalis; 10 – sulcus collateralis; 11 – sulcus rhinalis
On the superolateral surface of the temporal lobe are the superior temporal gyrus, gyrus temporalis superior, and middle temporal gyrus, gyrus temporalis medius. They are separated from each other by the superior temporal sulcus. The inferior temporal gyrus runs along the lower edge of the hemisphere, gyrus temporalis inferior, limited by the inferior temporal sulcus.
In the frontal, temporal and occipital lobes, the most prominent poles of the same name are distinguished ( polus frontalis, polus temporalis, polus occipitalis).
Island, insula (Reilii), clearly visible only when dividing the frontal/parietal and temporal lobes limiting the sulcus sulcus lateralis (Sylvii), at the bottom of which it is located. The islet has some resemblance to a cone, the base of which is surrounded by a deep circular groove of the islet, sulcus circularis insulae. Its surface is divided by the central groove of the insula, sulcus centralis insulae, on the anterior and posterior lobes. The posterior lobe usually consists of only one long gyrus of the insula, gyrus longus insulae, the anterior one contains several short convolutions of the insula, gyri breves insulae.
Furrows and convolutions of the medial surface of the cerebral hemispheres(Fig. 17). All lobes of the cerebral hemispheres have a continuation on the medial surface. The main groove here is the groove of the corpus callosum, sulcus corporis callosi, which surrounds the corpus callosum on its convex side. Approximately halfway between sulcus corporis callosi and the upper edge of the hemisphere is the cingulate groove, sulcus cinguli. It turns to the upper edge of the hemisphere with its posterior end - the marginal branch, ramus marginalis, and extends slightly onto the dorsolateral surface, posterior to the central sulcus. In front of the marginal branch, approximately above the middle of the corpus callosum, the cingulate gyrus gives off upward the paracentral sulcus, sulcus paracentralis. The direct continuation of the cingulate sulcus is the subparietal sulcus, sulcus subparietalis. Below the posterior end of the corpus callosum, two grooves begin with a common trunk, diverging towards the edge of the hemisphere: the already described parieto-occipital, sulcus parietooccipitalis, and calcarine groove, sulcus calcarinus. Near the occipital pole, the collateral groove begins on the lower surface of the hemisphere, sulcus collateralis, heading anteriorly. Its continuation in the anterior part of the temporal lobe is the olfactory sulcus, sulcus rhinalis. Lateral to the collateral sulcus is the occipitotemporal sulcus, sulcus occipitotemporalis.
The part of the medial surface lying above the cingulate gyrus belongs to the frontal lobe - this is the superior frontal gyrus extending here. Posteriorly, it reaches the level of the projection of the upper end of the central sulcus. Within the parietal lobe is the paracentral lobule, lobulus paracentralis, which below reaches the subparietal groove, sulcus subparietalis. The paracentral lobule connects the parietal lobe with the frontal lobe on the medial surface (more precisely, gyrus postcentralis With gyrus precentralis). Between pars marginalis sulci cinguli– in front, sulcus parietooccipitalis– behind and sulcus subparietalis– the precuneus lies below, precuneus. Between sulcus parietooccipitalis And sulcus calcarinus(already in the occipital lobe) there is a wedge, cuneus. On the medial surface of the same lobe is the lingual gyrus, gyrus lingualis, lying between sulcus calcarinus And sulcus collateralis. Below the latter is the medial occipitotemporal gyrus, gyrus occipitotemporalis medialis.
Within the temporal lobe on the medial surface of the hemispheres directly below the cerebral peduncles is the parahippocampal gyrus, gyrus parahippocampalis, which ends with a hook in front, uncus. The parahippocampal gyrus and uncus are separated from the cerebral peduncles by the hippocampal sulcus, sulcus hippocampalis. Below the parahippocampal gyrus lies the lateral occipitotemporal gyrus, gyrus occipitotemporalis lateralis. These gyri are separated posteriorly by the collateral sulcus, sulcus collateralis, in front – olfactory groove, sulcus rhinalis.
The inferior temporal gyrus runs along the lowermost edge of the medial surface of the temporal lobe. gyrus temporalis inferior, which is separated by the occipitotemporal sulcus, sulcus occipitotemporalis, from the lateral occipitotemporal gyrus.
The gyri, ring-shaped bordering the corpus callosum and the cerebral peduncles, extending from the frontal lobe to the temporal lobe, as a whole make up the limbic lobe, lobus limbicus. It consists of two parts: the cingulate gyrus, gyrus cinguli, and parahippocampal gyrus, gyrus parahippocampalis connected to each other by an isthmus, isthmus gyri cinguli, which begins behind the splenium of the corpus callosum. The cingulate gyrus lies between the sulcus of the corpus callosum, on the one hand, and the cingulate sulcus and the subparietal sulcus, on the other. The parahippocampal gyrus, as already noted, is bounded superiorly by the hippocampal sulcus, sulcus hippocampalis, below - the anterior end of the collateral and olfactory grooves.
Relief of the lower surface of the hemispheres(Fig. 18). On the lower (basal) surface of the frontal lobe there is an olfactory groove, sulcus olfactorius, running parallel to the longitudinal fissure of the brain. The olfactory tract passes through the groove. More lateral to the olfactory sulcus of the frontal lobe are the orbital sulci, sulci orbitales. Between these grooves there are gyri of variable shape: the straight gyrus, gyrus rectus, which is limited sulcus olfactorius And fissura longitudinalis cerebri, and orbital gyri, gyri orbitales, lying lateral to the olfactory sulcus.
Within the temporal and occipital lobes there is no clear boundary between the medial and inferior surfaces. They gradually transform into each other. In this regard, the grooves and convolutions located on the medial surface of the hemispheres in the lower parts of the occipital and temporal lobes are also visible on the lower surface of the hemispheres. In particular, within the occipital lobe is the medial occipitotemporal gyrus. Within the temporal lobe lie the parahippocampal, lateral occipitotemporal and inferior temporal gyri. The sequence of location of the named convolutions was considered in the lateral direction. The grooves separating these convolutions were named earlier.
Rice. 18. Relief of the lower surface of the cerebral hemispheres:
1– sulci orbitales; 2 – sulcus olfactorius
The given description of the grooves and convolutions of the cerebral cortex is schematic, since individual variants of their architectonics are quite common.
Projection and association centers of the cerebral cortex. The physiological permissibility of surgical interventions on the brain in most cases is determined by localization in the cortex cerebral hemispheres nerve centers. Projection centers are areas of the cerebral cortex, which represent the cortical representation of the analyzer and have a direct morphofunctional connection through afferent or efferent nerve pathways with neurons of the subcortical centers. Associative centers are areas of the cerebral cortex that do not have a direct connection with subcortical formations, but are connected by a temporary two-way connection with projection centers. Associative centers play a primary role in the implementation of higher nervous activity. Within the framework of this publication, we will not dwell in detail on a detailed description of each of the centers, but will only give their location in the cerebral cortex.
The projection center of general sensitivity (tactile, pain, temperature and conscious proprioceptive) is also called the skin analyzer of general sensitivity. It is localized in the postcentral gyrus cortex.
The projection center of motor functions (kinesthetic center), or motor analyzer, is located in the motor area of the cortex, which includes the precentral gyrus and paracentral lobule.
The projection center of hearing, or the nucleus of the auditory analyzer, is located in the middle third of the superior temporal gyrus, mainly on the surface of the gyrus facing the insula.
The projection center of vision, or the nucleus of the visual analyzer, is localized on the medial surface of the occipital lobe, along the edges of the calcarine groove.
The projection center of smell, or the nucleus of the olfactory analyzer, is located on the medial surface of the temporal lobe, in the cortex of the parahippocampal gyrus and in the hook (limbic region).
The projection center of taste, or the core of the taste analyzer, is located in the same place as the projection center of smell, i.e. in the limbic region of the brain.
Projected center of sensitivity from internal organs, or visceroception analyzer, is located in the lower third of the postcentral and precentral gyri.
The projection center of vestibular functions, the vestibular analyzer, undoubtedly has its representation in the cerebral cortex, but information about its localization is ambiguous. It is generally accepted that the projection center of vestibular functions is located on the lateral surface of the temporal lobe, in the region of the middle and inferior temporal gyri.
The associative center of stereognosis, or the nucleus of the skin analyzer for recognizing objects by touch, is located in the superior parietal lobule.
The association center of the body diagram is located in the parietal lobe, in the region of the intraparietal sulcus.
The associative center of praxia, or the analyzer of purposeful habitual movements, is located in the inferior parietal lobule, in the cortex of the supramarginal gyrus, in the left hemisphere of the brain for right-handers, and in the right hemisphere for left-handers. The associative center of vision, or visual memory analyzer, is located on the superolateral surface of the occipital lobe, in the left hemisphere for right-handers, and in the right hemisphere for left-handers.
The associative center of hearing, or the acoustic center of speech, is also called Wernicke's center (after the name of the German neurologist and psychiatrist Karl Wernicke, who first described in 1874 the symptoms of damage to the posterior third of the superior temporal gyrus, within which this center is located on the dominant hemisphere).
The associative motor center of speech (speech motor), or the center of speech articulation, is called Broca's center (after the name of Paul Broca, a French anatomist and surgeon, who in 1861 for the first time demonstrated at a meeting of the Paris Anthropological Society the brain of a patient who had motor aphasia during his lifetime , with a lesion in the posterior third of the inferior frontal gyrus). The center is located on the dominant hemisphere.
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The last functional part of the brain covers the anterior half of the cerebral hemispheres. Here are the centers that control our actions.
From here, nerve pathways lead to the muscles of the limbs, face, lips, eyes and tongue. Impulses sent from the “motor” centers in the cortex allow us to move, speak and control facial expressions - we blink, smile, frown and pout. Although the cerebral hemispheres appear to be exactly the same, they nevertheless perform different functions. They are connected to each other by a strip nerve tissue
called the corpus callosum. If it is removed or damaged, both hemispheres act relatively independently of each other, generating their own thoughts and emotions. Left hemisphere controls movements right side bodies. Here are the most important centers of speech, language, mathematical abilities and. logical thinking Right hemisphere is responsible for the left side and is the center, musical talent and abstract thinking. At the same time, there is a continuous exchange of impulses between the hemispheres, and even if the corpus callosum is cut, both halves of the brain still act more or less harmoniously.
The cerebral cortex covers the surface of the hemispheres and forms a large number of grooves of varying depth and length (lat. sulci cerebri). Between the grooves there are cerebral convolutions of varying sizes (lat. gyri cerebri)
In each hemisphere the following surfaces are distinguished:
convex superolateral surface (lat. facies superolateralis), adjacent to the inner surface of the bones of the cranial vault
the lower surface (lat. facies inferior), the anterior and middle sections of which are located on the inner surface of the base of the skull, in the region of the anterior and middle cranial fossa, and the posterior ones - on the tentorium of the cerebellum
medial surface (lat. facies medialis), directed towards the longitudinal fissure of the brain
These three surfaces of each hemisphere, passing one into another, form three edges. The superior edge (lat. margo superior) separates the superolateral and medial surfaces. The inferolateral edge (lat. margo inferolateralis) separates the superolateral surface from the bottom. The inferomedial edge (lat. margo inferomedialis) is located between the lower and medial surfaces
In each hemisphere, the most prominent places are distinguished: in front - the frontal pole (lat. polus frontalis), in the back - occipital (lat. polus occipitalis), and on the side - temporal (lat. polus temporalis)
The hemisphere is divided into five lobes. Four of them are adjacent to the corresponding bones of the cranial vault:
frontal lobe (lat. lobus frontalis)
parietal lobe (lat. lobus parietalis)
occipital lobe (lat. lobus occipitalis)
temporal lobe (lat. lobus temporalis)
The fifth - insular lobe (lat. lobus insularis) (island) (lat. insula) - is located deep in the lateral fossa of the cerebrum (lat. fossa lateralis cerebri), separating the frontal lobe from the temporal lobe
Grooves and convolutions of the superolateral surface
Frontal lobe - indicated in pink
Parietal lobe - indicated in green
Temporal lobe - indicated in yellow
Occipital lobe - indicated in blue
Frontal lobe
The frontal lobe is separated from the parietal lobe by a deep central groove (lat. sulcus centralis). It begins on the medial surface of the hemisphere, passes to its superolateral surface, runs along it slightly obliquely, from back to front, and usually does not reach the lateral sulcus of the brain
Approximately parallel to the central sulcus is the precentral sulcus (lat. sulcus precentralis), which does not reach the upper edge of the hemisphere. The precentral sulcus borders the front of the precentral gyrus (lat. gyrus precentralis).
The superior and inferior frontal sulci (lat. sulci frontales superior et inferior) are directed forward from the precentral sulcus. They divide the frontal lobe into:
superior frontal gyrus (lat. gyrus frontalis superior), which is located above the superior frontal sulcus and passes to the medial surface of the hemisphere
the middle frontal gyrus (lat. gyrus frontalis medius), which is bounded by the superior and inferior frontal sulci. The orbital (anterior) segment of this gyrus passes onto the inferior surface of the frontal lobe
the inferior frontal gyrus (lat. gyrus frontalis inferior), which lies between the inferior frontal sulcus and the lateral sulcus of the brain and the branches of the lateral sulcus is divided into a number of parts
The lateral groove (lat. sulcus lateralis) is one of the deepest grooves in the brain. It separates the temporal lobe from the frontal and parietal lobes. The lateral groove lies on the superolateral surface of each hemisphere and runs from top to bottom and anteriorly. In the depths of this groove there is a depression - the lateral fossa of the cerebrum (lat. fossa lateralis cerebri), the bottom of which is the outer surface of the insula
Small grooves called rami extend upward from the lateral sulcus. The most constant of them are the ascending (lat. ramus ascendens) and anterior (lat. ramus anterior) branches. The superior posterior section of the groove is called the posterior branch (lat. ramus posterior)
The inferior frontal gyrus, within which the ascending and anterior branches pass, is divided into three parts:
posterior - tegmental part (lat. pars opercularis), limited in front by the ascending branch
middle - triangular part (lat. pars triangularis), lying between the ascending and anterior branches
anterior - orbital part (lat. pars orbitalis), located between the anterior branch and the inferolateral edge of the frontal lobe
Parietal lobe
It lies posterior to the central sulcus, which separates it from the frontal. It is delimited from the temporal by the lateral sulcus of the brain, from the occipital by part of the parieto-occipital sulcus (lat. sulcus parietooccipitalis)
The postcentral gyrus (lat. gyrus postcentralis) runs parallel to the precentral gyrus. From it posteriorly, almost parallel to the longitudinal fissure of the cerebrum, there is an intraparietal groove (lat. sulcus intraparietalis), dividing the postero-superior parts of the parietal parts of the parietal lobe into two gyri: the upper (lat. lobulus parietalis superior) and the lower (lat. lobulus parietalis inferior) parietal lobules. In the inferior parietal lobe, two relatively small gyri are distinguished: the supramarginal gyrus (lat. gyrus supramarginalis), which lies anteriorly and closes the posterior sections of the lateral sulcus, and the angular gyrus located posterior to the previous one (lat. gyrus angularis), which closes the superior temporal sulcus
Between the ascending and posterior branches of the lateral sulcus of the brain there is a section of the cortex designated as the frontoparietal operculum (lat. operculum frontoparietalis). It includes the posterior part of the inferior frontal gyrus, the lower parts of the precentral and postcentral gyri, as well as the lower part of the anterior part of the parietal lobe
Occipital lobe
On the superolateral surface it has no boundaries separating it from the parietal and temporal lobes, with the exception of the upper part of the parieto-occipital sulcus, which is located on the medial surface of the hemisphere and separates the occipital lobe from the parietal lobe
The largest of the grooves is the transverse occipital groove (lat. sulcus occipitalis transversus). Sometimes it is a posterior continuation of the intraparietal sulcus and in the posterior section passes into the unstable semilunar sulcus (lat. sulcus lunatus)
Temporal lobe
Has the most pronounced boundaries. It has a convex lateral surface and a concave bottom surface. The obtuse pole of the temporal lobe faces forward and slightly downward. The lateral cerebral sulcus sharply demarcates the temporal lobe from the frontal lobe
Two grooves located on the superolateral surface: the upper (lat. sulcus temporalis superior) and the lower (lat. sulcus temporalis inferior) temporal sulci, following almost parallel to the lateral sulcus of the brain, divide the lobe into three temporal gyri: upper, middle and lower (lat. gyri temporales superior, medius et inferior)
Those parts of the temporal lobe that are directed towards the lateral groove of the brain are cut by short transverse temporal grooves (lat. sulci temporales transversi). Between these grooves lie 2-3 short transverse temporal gyri, associated with the gyri of the temporal lobe (lat. gyri temporales transversi) and the insula
Insula (islet)
It lies at the bottom of the lateral fossa of the cerebrum (lat. fossa lateralis cerebri).
It is a three-sided pyramid, facing its apex - the pole of the insula - anteriorly and outwardly, towards the lateral sulcus. From the periphery, the insula is surrounded by the frontal, parietal and temporal lobes, which participate in the formation of the walls of the lateral sulcus of the brain
The base of the island with three sides surrounded by a circular groove of the islet (lat. sulcus circularis insulae).
Its surface is cut by a deep central groove of the insula (lat. sulcus centralis insulae). This groove divides the insula into anterior and posterior parts.
On the surface there are a large number of small convolutions of the insula (lat. gyri insulae). The large anterior part consists of several short convolutions of the insula (lat. gyri breves insulae), the posterior part consists of one long convolution (lat. gyrus longus insulae)