Telencephalon

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TELENCÉPHALO

The telencephalon comprises both right and left cerebral hemispheres, and a small midline located in the anterior portion of the III ventricle.

The two cerebral hemispheres are incompletely separated by the longitudinal cleft of the brain, the floor of which is formed by a broad band of commissural fibers called the corpus callosum, the main means of union between the two hemispheres. The hemispheres have cavities, the right and left lateral ventricles, which communicate with the III ventricle through the interventricular foramina.

Cerebral Hemispheres

Each hemisphere has three poles: Frontal, Occipital and Temporal; and three faces: Super lateral (convex); Medial (flat); and Bottom or base of the brain (irregular), resting anteriorly on the anterior and middle floors of the base of the skull and posteriorly on the cerebellum tent.

Cerebral Hemisphere - Poles

Grooves and Turns:

During embryonic development, when brain size increases rapidly, the gray matter of the cortex increases faster than the underlying white matter. As a result, the cortical region curls and bends over itself. Therefore, the surface of the brain of man and various animals has depressions called grooves, which delimit the gyrus or brain circumvolutions. The existence of the grooves allows considerable increase in brain volume and it is known that about two thirds of the area occupied by the cerebral cortex is "hidden" in the grooves.
In either hemisphere, the two most important grooves are the lateral groove and the central groove.

Side Groove: is the groove that separates the frontal lobe from the temporal lobe. It is subdivided into ascending, anterior and posterior.

Central Groove: separates the parietal lobe from the frontal. The central groove is flanked by two parallel turns, one anterior, pre-central gyrus, and the other posterior, postcentral gyrus. Areas in front of the central furrow relate to MOTRICITY, while those behind this furrow relate to SENSITIVITY.

Cerebral Hemisphere - Lateral View - Central and Lateral Groove

Another important sulcus in the telencephalon on the medial surface is the Parieto-occipital Groove, which separates the parietal lobe from the occipital lobe.
Cerebral Hemisphere - Medial View - Parieto-occipital Groove
Brain wolves are named after their location in relation to the skull bones. So we have five wolves: Frontal, Temporal, Parietal, Occipital and the Insular Wolf, which is the only one that does not relate to any skull bone, as it is situated deep in the lateral groove.

The division of the wolves does not correspond much to a functional division, except for the occipital lobe that seems to be related only to vision.

The frontal lobe is located above the lateral sulcus and in front of the central sulcus. On the medial face of the brain, the anterior limit of the occipital lobe is the parieto-occipital groove. On its superolateral face, this boundary is arbitrarily situated on an imaginary line joining the termination of the parieto-occipital groove on the upper edge of the hemisphere to the pre-occipital notch on the inferolateral edge, about 4 cm. of the occipital pole. From the middle of this imaginary line part a second imaginary line towards the posterior branch of the lateral sulcus and, together with this branch, limits the temporal lobe of the parietal lobe.

Brain Wolves
Insula wolf

Super-lateral face:

Frontal lobe Temporal wolf Parietal wolf Occipital Wolf Insula wolf
Frontal lobe   Temporal wolf   Parietal wolf   Occipital Wolf   Insula wolf

Frontal lobe:

Furrows:
Precentral Groove: more or less parallel to the central groove.
Upper Front GrooveIt begins in the upper portion of the pre-central sulcus and is directed anteriorly into the frontal lobe. It is perpendicular to it.
Lower Frontal Groove: Starting from the lower portion of the pre-central groove, it moves forward and downward.

Frontal Wolf Grooves

Turns:
Pre-Center Turn: It is located between the central groove and the pre-central groove. In this gyrus is located the main motor area of the brain (motor cortex).
Upper Front Swivel: It is located above the upper frontal groove.
Medium Front Spin: It is located between the upper and lower frontal groove.
Lower Front Rotation: It is located below the inferior frontal sulcus. The lower frontal gyrus of the left hemisphere is the cortical center of the spoken word.

Front Wolf Turns

Temporal wolf:

Grooves:
Superior Temporal GrooveIt begins near the temporal pole and runs back parallel to the posterior branch of the lateral sulcus, ending in the parietal lobe.
Lower Temporal Groove: Parallel to the superior temporal sulcus is generally formed by two or more discontinuous parts.
Temporal Wolf GroovesTurns:
Superior Temporal Turn: It is located between the lateral sulcus and the superior temporal sulcus.
Average Temporal Turn: It is located between the superior temporal and inferior temporal grooves.
Lower Temporal Turn: It is located below the inferior temporal sulcus and is limited to the occipital-temporal sulcus.
Moving away from the lips of the lateral sulcus is its floor, which is part of the superior temporal gyrus. The upper portion of this floor is traversed by small transverse turns, the transverse time turns, of which the most evident is the anterior transverse time turn. This is important because the cortical center of hearing is located.
Temporal Wolf Turns

Parietal wolf:

Grooves:
Postcentral Groove: It is located posterior to the post-central gyrus. It is parallel to the central groove.
Intraparietal GrooveIt is usually located perpendicular to the postcentral sulcus (with which it may be attached) and extends backward to terminate in the occipital lobe.
Parietal Wolf Grooves
Unlike other wolves, the parietal lobe has one gyrus and two lobes:
Post Center Turn: It is located between the central sulcus and the postcentral sulcus. It is in the postcentral gyrus that one of the most important sensory areas of the cortex, the somesthetic area, is located.
Upper Parietal Lobe: It is located superior to the intra-parietal sulcus.
Lower Parietal Lobe: it is located inferior to the intraparietal sulcus. In this, two turns are described: the supramarginal gyrus, curving around the end of the posterior branch of the lateral sulcus, and the angular gyrus, curving around the terminal and ascending portion of the superior temporal sulcus.
Parietal Wolf Turns

Occipital Wolf:

The occipital lobe occupies a relatively small portion of the superolateral surface of the brain, where it has small, irregular and uneven shifts and turns. The main grooves and turns of this wolf are visualized on the medial face of the brain.
Occipital Wolf

Insula wolf:

The insula lobe is visualized by moving the lips away from the lateral sulcus. The insula has a conical shape and its apex, facing downwards and forwards, is called the insula lumen.
Central groove of Inula: part of the circular groove in the upper portion of the insula and is directed in the anterior-inferior direction. Divide the insula into two parts: long turns and short turns.
Insular Circular Groove: surrounds the insula at its upper edge.
Insula Wolf Grooves

Turns:

Long Turns of Insula: are located posterior to the central groove of the insula.

Insular Short Turns: they are located anterior to the central groove of the insula.
Insula Wolf Turns

SUMMARY OF BRAIN SUPER-SIDE FACE SPIN
Grooves in the Telencephalon Side View
Source: NETTER, Frank H .. Atlas of Human Anatomy. 2 ed. Porto Alegre: Artmed, 2000.
SUPER-SIDE BRAIN FACE
SUPER-SIDE BRAIN FACE
Source: NETTER, Frank H .. Atlas of Human Anatomy. 2 ed. Porto Alegre: Artmed, 2000.
INSULA WOLF
 Insula wolf
Source: NETTER, Frank H .. Atlas of Human Anatomy. 2 ed. Porto Alegre: Artmed, 2000.

Medial Face:

Callosum - Medial Face Frontal and Parietal Lobe - Medial Face Occipital Wolf - Medial Face
Callosum

Fornix

Hairy Septum

  Frontal lobe

Parietal wolf

  Occipital Wolf

 

Corpus callosum, fornix and pellucid septum:

Callosum: is the largest of the interhemispheric commissures. It is formed by a large number of myelin fibers that cross the median sagittal plane and penetrate each side into the medullary white center of the brain, joining symmetrical areas of the cortex of each hemisphere. In sagittal section of the brain we can identify the divisions of the corpus callosum: a dorsally arched white lamina, the trunk of the corpus callosum, which subsequently dilates into the splenium of the corpus callosum and flexes anteriorly toward the base of the brain to form the knee of the corpus callosum. corpus callosum. It tapers to form the corpus callosum rostrum, which continues into a thin lamina, the rostral lamina to the anterior commissure. Between the anterior commissure and the optic chiasm is the terminal lamina, a thin white matter lamina that also joins the hemispheres and constitutes the anterior limit of the III ventricle.

DIVISIONS OF THE CALLY BODY AND FORNIX & #8211; INFERO-MEDIAL BRAIN FACE
 
DIVISIONS OF THE CALUSO BODY AND FORNIX - INFEROMIAL BRAIN FACE
Source: NETTER, Frank H .. Atlas of Human Anatomy. 2 ed. Porto Alegre: Artmed, 2000.

FornixEmerging below the splenium of the corpus callosum and arching toward the anterior commissure is the fornix, a complex bundle of fibers that, however, cannot be seen to its full extent in a sagittal section of the brain. It consists of two lateral and symmetrical halves spaced apart at the ends and joined together in the corpus callosum path. The intermediate portion in which the two halves join together constitutes the body of the fornix and the distal ends are respectively the columns of the (anterior) fornix and the branches of the (posterior) fornix. The columns of the fornix end in the corresponding nipple body crossing the lateral wall of the III ventricle. The branches of the fornix diverge and penetrate each side into the inferior horn of the lateral ventricle, where they attach to the hippocampus. At the point where the legs of the phoenix separate, some fibers pass from side to side, forming the commissure of the phoenix.

FORNIX AND HIPOCAMP
 
FORNIX AND HIPOCAMP
Source: NETTER, Frank H .. Atlas of Human Anatomy. 2 ed. Porto Alegre: Artmed, 2000.
TOP VIEW OF FORNIX AND HIPOCAMP
TOP VIEW OF FORNIX AND HIPOCAMP

 

Source: NETTER, Frank H .. Atlas of Human Anatomy. 2 ed. Porto Alegre: Artmed, 2000.

Hairy Septum:

Hairy SeptumBetween the corpus callosum and the fornix extends the pellucid septum, consisting of two thin sheets of nervous tissue that delimit a very narrow cavity, the pellucid septum cavity. The pellucid septum separates the two lateral ventricles.

 

Frontal and Parietal Wolf:

PELUCID SEPTEM & #8211; BRAIN MEDICAL VIEW
 
PELUCID SEPTO - MEDIAL VIEW OF BRAIN
Source: NETTER, Frank H .. Atlas of Human Anatomy. 2 ed. Porto Alegre: Artmed, 2000.

In the medial part of the brain, there are two grooves that pass from the frontal lobe to the parietal lobe:

Corpus Callosum Groove: begins below the corpus callosum rostrum, bypasses the trunk and splenium of the corpus callosum, where it continues into the temporal lobe with the hippocampal groove.

Cingulate Groove: has its course parallel to the groove of the corpus callosum, from which it is separated by the cingulate rotation. It terminates posteriorly in two grooves: marginal branch of the cingulate gyrus, final portion of the cingulate gyrus sulcus that crosses the upper margin of the hemisphere, and the subtietal sulcus which continues posteriorly toward the parietoocipital sulcus.

Paracentral FurrowIt stands out from the cingulate groove towards the upper margin of the hemisphere, which delimits, with the cingulate groove and marginal groove, the paracentral lobe.

Grooves of Medial View of the Brain

Cingulate Turn: Contours the corpus callosum, attaching to the para-hippocampal gyrus by the isthmus of the cingulate gyrus. It is traversed by a bundle of fibers, the fascicle of the cingulate.

Paracentral Lobe: is located between the marginal groove and the paracentral groove. In the anterior and posterior part of this lobe are the motor and sensory areas related to the leg and foot.

Pre-tunnelsIt is located superior to the parieto-occipital sulcus in the parietal lobe.

Upper Front Swivel: has already been described above in the study of the lateral face of the brain.

Medial View of the Brain

Occipital Wolf:

Calcarino Furrow: It begins below the corpus callosum splenium and has an arched path towards the occipital pole. On the lips of the calcarine groove is the cortical center of vision.

Parieto-occipital groove: is the groove that separates the occipital lobe from the parietal lobe.

Occipital Wolf Grooves of Medial Brain View

TunnelsIt is located between the parieto-occipital sulcus and the calcarine sulcus. It is a complex spin of triangular shape. Ahead of the tunnels, in the parietal lobe, we have the pre-tunnels.

Medial Occipito-Giro: It is located below the calcarine groove. This gyrus continues anteriorly with the para-hippocampal gyrus of the temporal lobe.

Occipital Wolf Turns of Medial Brain View

Bottom Face:

Temporal Wolf - Lower View Frontal lobe
Temporal wolf  Frontal lobe   

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Temporal wolf:

Occipito-Temporal Groove: It is located between the lateral occipito-temporal gyrus and medial occipito-temporal gyrus.

Collateral Groove: starts near the occipital pole and moves forward. The collateral sulcus may be continuous with the renal sulcus, which separates the most anterior part of the para-hippocampal gyrus from the rest of the temporal lobe.

Hippocampal Groove: originates in the splenium region of the corpus callosum, where it continues with the sulcus of the corpus callosum and goes to the temporal pole, where it ends by separating the parahypocampal gyrus from the soleus.

Calcarino Furrow: is best viewed on the medial face of the brain. On the underside, the posterior portion separates the para-hippocampal gyrus from the isthmus of the cingulate gyrus.

Grooves in the Telencephalon Bottom View

Lateral Occipito-TurnIt is located in the lateral region of the underside of the brain surrounding the medial occipito-temporal gyrus and the para-hippocampal gyrus.

Medial Occipito-Giro: It is also seen on the medial face of the brain, but occupies a significant area on the underside. It is located between the lateral occipito-temporal gyrus, para-hippocampal gyrus and the cingulate isthmus.

Para-hippocampal Turning: Attaches posteriorly to the cingulate gyrus through a narrow gyrus, the isthmus of the cingulate gyrus. Thus the soleus, the para-hippocampal gyrus, the isthmus of the cingulate gyrus, and the cingulate gyrus constitute the limbic lobe, an important part of the limbic system, related to emotional behavior and control of the autonomic nervous system. The anterior portion of the para-hippocampal gyrus bends around the hippocampal groove to form the sole

Telecephalus Bottom View Turns

Frontal lobe:

The inferior face of the frontal lobe has the following structures: olfactory groovedeep and anteroposterior direction; O straight turn, which is located medially to the olfactory groove and continues dorsally as the upper front gyrus. The rest of the lower face of the frontal lobe is occupied by very irregular grooves and turns, the grooves and orbital turns.

Front Lobe Groove and Turns - Bottom View

 LOWER BRAIN FACE
 
LOWER BRAIN FACE
Source: NETTER, Frank H .. Atlas of Human Anatomy. 2 ed. Porto Alegre: Artmed, 2000.
SUMMARY OF BRAIN MEDIAL FACE SPIN
 
MEDIAL BRAIN FACE TURNTABLES
Source: NETTER, Frank H .. Atlas of Human Anatomy. 2 ed. Porto Alegre: Artmed, 2000.

Rhinocephalus:

The olfactory bulb is a flat ovoid dilation of gray matter that continues posteriorly with the olfactory tract, both housed in the olfactory groove. The olfactory bulb receives filaments that constitute the olfactory nerve. Subsequently, the olfactory tract forks into the lateral and medial olfactory striae, which delimit a triangular area, the olfactory triangle. Across the olfactory trine and ahead of the optic tract is an area containing a series of small holes for the passage of vessels, the perforated substance from the anterior.

RINENCÉPHALO & #8211; THE ANATOMY OF THE OLFACTORY NERVE
 
 ANATOMY OF THE OLFACTORY NERVE
Source: NETTER, Frank H .. Atlas of Human Anatomy. 2 ed. Porto Alegre: Artmed, 2000.

Lateral Ventricle Morphology:

The cerebral hemispheres have cavities lined with ependima and containing cerebrospinal fluid, the left and right lateral ventricles, which communicate with the III ventricle through the interventricular foramen. Except for the foramen, each ventricle is a closed cavity that has a central part and three horns that correspond to the three poles of the cerebral hemisphere. The parts that protrude to the frontal, occipital and temporal pole respectively are the anterior, posterior and inferior horn. Except for the inferior horn, all parts of the lateral ventricle have the roof formed by the corpus callosum.

SIDE VENTRICLE MORPHOLOGY
 
SIDE VENTRICLE MORPHOLOGY
Source: NETTER, Frank H .. Atlas of Human Anatomy. 2 ed. Porto Alegre: Artmed, 2000.
SIDE VENTRICLE MORPHOLOGY
 
SIDE VENTRICLE MORPHOLOGY
Source: NETTER, Frank H .. Atlas of Human Anatomy. 2 ed. Porto Alegre: Artmed, 2000.

Internal Organization of the Brain Hemispheres:

Each hemisphere has a superficial layer of gray matter, the cerebral cortex, which lines a center of white matter, the medullary center of the brain, or semioval center. Within this white matter there are masses of gray matter, the nuclei of the base of the brain.

Medullary white center of the brain: It is formed by myelin fibers. Two groups of fibers are distinguished: Projection and Association. Projection fibers connect the cerebral cortex to subcortical centers; Association fibers join cortical areas located at different points in the brain.

The Projection Fibers They are arranged in two bundles: the fornix and the inner capsule.

The fornix It attaches the hippocampal cortex to the nipple body and contributes a little to the formation of the white medullary center. It has been better described earlier on this page.

The Inner Capsule contains the vast majority of fibers that leave or enter the cerebral cortex. These fibers form a compact bundle that separates the laterally located lentiform nucleus from the medially located caudate and thalamus nucleus. Above the level of these cores, the fibers of the inner capsule become the radiated crown.

Radiated Crown
The inner capsule is distinguished from an anterior branch, situated between the head of the caudate nucleus and the lentiform nucleus, and a much larger posterior branch, situated between the lentiform nucleus and the thalamus. These two portions of the inner capsule are at an angle forming the knee of the inner capsule.

Inner Capsule - Bottom View

Association fibers are divided into intrahemispheric and interhemispheric association fibers.

Between the Intrahemispheric Association FibersI will mention the four most important issues:
 Cingulate fascicle & #8211; Joins the frontal and temporal lobes.
 Superior Longitudinal fascicle & #8211; Joins the frontal, parietal and occipital lobes. It can also be called an arched fascicle.
 Lower Longitudinal fascicle & #8211; Joins the occipital and temporal lobe.
 Uniform fascicle & #8211; Joins the frontal and temporal lobes.

Intrahemispheric Association Fibers

Between the Interhemispheric Association Fibers, that is, those that cross the median plane to join symmetrical areas of the two hemispheres, we find three telencephalic commissures: Corpus Callosum, Forix Commissioner and Previous Commissioner, already studied above.

Interhemispheric Association Fibers
Base Cores:

 Caudate Core: It is an elongated and rather large mass of gray matter, related in all its extension to the lateral ventricles. Its anterior extremity is very dilated, it constitutes the head of the caudate nucleus, which protrudes from the floor of the anterior horn of the lateral ventricle. It gradually continues with the caudate nucleus body, situated on the floor of the central part of the lateral ventricle. It gradually tapers to form the tail of the caudate nucleus, which is long and strongly arched, extending to the anterior end of the inferior horn of the lateral ventricle. Because of its strongly arcuate shape, the caudate nucleus appears sectioned twice in certain horizontal and frontal sections of the brain. The head of the caudate nucleus merges with the anterior part of the lentiform nucleus.

CAUSED CORE, LENTIFORM CORE AND FRIENDLY BODY
 CAUSED CORE, LENTIFORM CORE AND FRIENDLY BODY
Source: NETTER, Frank H .. Atlas of Human Anatomy. 2 ed. Porto Alegre: Artmed, 2000.

 Lentiform Core: has the shape and approximate size of a Brazil nut. It does not appear on the ventricular surface, but lies deep within the hemisphere. Medially it relates to the inner capsule, which separates it from the caudate nucleus and the thalamus; laterally it relates to the insula cortex, from which it is separated by white matter and the cloister.
The lentiform nucleus is divided into putamen and pale globe by a thin lamina of white matter, the lateral medullary lamina. The putamen lies laterally and is larger than the pale globe, which is arranged medially. In transverse sections of the brain, the pale globe has a lighter coloration than the putamen due to the presence of myelin fibers passing through it. The pale globe is subdivided by a white matter lamina, the medial medullary lamina, into the outer and inner parts (see figure below).

 Cloister: is a thin gray matter cap situated between the cortex of the insula and the lentiform nucleus. It separates from the cortex of the insula by a thin white blade, the extreme capsule. Between the cloister and the lentiform nucleus there is another white lamina, the outer capsule (see figure below).

 Amygdaloid Body: is a spheroidal mass of gray matter about 2 cm in diameter situated at the temporal pole of the cerebral hemisphere. It makes a slight protrusion on the ceiling of the terminal part of the lower horn of the lateral ventricle. The amygdaloid body is part of the limbic system and is an important regulator of sexual behavior and aggression (see figure above).

 Accumbens Core: mass of gray matter in the zone of union between the putamen and the head of the caudate nucleus.

 Meynert Basal Core: difficult to see macroscopically. It is located at the base of the brain, between the anterior perforated substance and the pale globe, a region known as the innominate substance. Contains large neurons rich in acetylcholine.
Base Cores

BASE CORES & #8211; BRAIN CROSS SECTION
 
BASE CORES - BRAIN CROSS SECTION
Source: NETTER, Frank H .. Atlas of Human Anatomy. 2 ed. Porto Alegre: Artmed, 2000.

At the end of this content, I would also like to illustrate an image with some important areas considering the telencephalon as a whole. As stated earlier, division by wolves and furrows is only didactic, as the brain functions as a whole independent of wolves, but some areas are specific and well localized, such as those shown in the figure below:

Brain Side View

Structures of
Nervous system
Nervous tissue

Spinal cord

Brainstem

Cerebellum

Diencephalon

Meninges and CSF

Brain Vascularization

Peripheral Nervous System

 

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