The brain is located in the cranial cavity. It consists of 5 departments: the medulla oblongata, the posterior, middle, intermediate and final, also called the cerebral hemispheres.
The upper ventral surface (medulla oblongata, as well as other departments) corresponds to the inner concave part of the skull. On the other hand, the lower surface, which is the base of the brain, has a complex structure that corresponds to the cranial fossa in this place.
Let us examine in detail from which the surface of the cerebral hemispheres is formed.
End brain
Two hemispheres, separated from each other by a longitudinal gap, enter the final brain . In depth, they are connected by a corpus callosum and commissures. The composition of the brain includes the left and right lateral ventricles located in one and the other hemispheres. Outside, the surface of the cerebral hemispheres is formed by the cortex, called the “cloak”. The cloak is deeper than white and gray matter. The border between the diencephalon and the final brain is located where the inner capsule is adjacent to the thalamus from the lateral side.
Hemisphere
The cortex, from which the surface of the cerebral hemispheres is formed, is a thin gray plate. The hemispheres consist of the following parts:
- superior lateral - convex;
- medial - flat;
- lower - with a complex relief.
Each surface is divided by its edges:
- top;
- lower lateral;
- lower medial.
The protruding sections are called:
- frontal pole;
- occipital pole;
- temporal pole.
The surface of the cerebral hemispheres has a complex structure, with a large number of furrows and convolutions of different sizes, shapes and directions.
Frontal lobes of the upper lateral surface
The frontal lobes are located in the front parts of the brain, ending in the frontal pole and bordering the lateral groove at the bottom and the central furrow at the back. The latter is in the frontal plane, starting from the medial surface and dissecting the upper edge, it goes down, not reaching the lateral groove.
Occipital lobe
This part is located behind the parieto-occipital sulcus, whereby the upper lateral surface of the cerebral hemisphere continues. Other fractions are smaller than this. It has a very diverse grooves and convolutions and ends with an occipital pole.
Parietal lobe
The parietal lobe is located on the back side of the central sulcus. On the one hand, the parieto-occipital sulcus, which is located on the medial surface, acts as the border. It dissects the hemisphere from above and passes to the upper lateral surface.
Temporal lobe
This part is located on the lower sections on the sides of the hemispheres. On the one hand, it is divided by the frontal, and on the other - the parietal lobe through a deep lateral groove. The edge that covers the islet lobe is called the temporal lobe. At the top, the temporal lobe has a temporal pole. Two grooves are distinguished from the side, which are almost parallel to the lateral. Brains roughly pass along the furrows.
Islet of the upper lateral surface
This lobe is located inside the lateral groove. It becomes noticeable if you remove the parietal, frontal and temporal lobes or push them apart. Its circular furrow separates from all other lobes. The surface of the island has different lengths of the convolution. Between the one located at the back and those located below and in front is the central groove of the island. And on the lower front part there is a small thickening without any furrows, which is called the threshold of the island.
Medial surface
The medial surface of the brain is formed by all lobes, except for the islet. A groove is located above the corpus callosum. It is directed forward and down. At the top of it is a girdle groove, which originates from the beak of the corpus callosum, goes up, and then turns back, parallel to its furrow. It ends above the roller in the form of a darkened furrow. Here, an upward branch branches off from the cingulate sulcus.
Between the furrows of the cingulate and corpus callosum, the cingulate gyrus is located. On the one hand, it narrows, creating the isthmus of the cingulate gyrus, turning into a wider gyrus. The gyrus along with the isthmus is called vaulted. In its depth there is a thin gray plate divided by small grooves. This is a dentate gyrus. The medial surface of the brain, which is located between the upper edge of the hemisphere and the lumbar groove, refers to the lobes of the frontal and parietal.
The medial surface of the superior frontal gyrus is located in front of the upper edge of the central groove. Between the front and rear edges there is a preclip, which refers to the parietal lobe.
At an acute angle ajar at the back, there are the parieto-occipital and spur furrows. The latter originates on the medial surface of the occipital pole and moves forward to the cingulate gyrus. This triangle-shaped area is called a wedge. The spur furrow, which limits the lingual gyrus, stands out well. Beneath the latter is a collateral groove.
Bottom surface
The surface of the cerebral hemispheres is formed in the lower part rather difficult. Its anterior sections consist of the frontal lobe. The temporal pole extends behind. The lower parts of the occipital and temporal lobes belong to the same surface.
Below the frontal lobe, at the same level along the longitudinal fissure, is the olfactory groove, at the base of which the olfactory tract and bulb lie, turning into a triangle. Lateral and olfactory strips stand out in it. Part of the frontal lobe between the olfactory groove and the longitudinal fissure is called the straight gyrus. The site on the side of the olfactory sulcus is divided by the orbital fissures into the orbital gyrus of various shapes and sizes.
The lower surface of the brain behind is distinguished by a collateral groove located laterally and below the lingual gyrus on the temporal and occipital lobes. A little farther in front of the collateral sulcus is the nasal sulcus in front, limited to the parahippocampal gyrus. The medial occipital-temporal gyrus is located somewhat lateral to the collateral. Between her and the adjacent lateral occipital-temporal gyrus there is an occipital-temporal groove. But the borders here are the lower lateral hemisphere.
Limbic system
Separately, it should be said about those areas that are mainly on the medial surface and are formed through emotions, motivational behavior, sleep and other things. They were called the limbic system. The reactions here are created through the original olfactory functions. Because of their morphological basis are those areas that emerge from the lower lateral parts of the brain bladder, called the olfactory brain.
The limbic system consists of the olfactory tract, bulb, triangle, anterior perforated substance located on the lower surface of the frontal lobe, and other components. The inclusion of these sites was made possible due to the similar structure, mutual relations and similarity of many reactions.
Conclusion
From the article we learned from what the surface of the brain is formed. It is important to know that the human brain, having similar characteristics for all of humanity, is nevertheless very different in different people. The same applies to its surface. It is different for representatives of both sexes, ethnic groups, and even family members.
To date, studies have been conducted in four generations. It was revealed that the main features remain unchanged. But the surface is changing and is so individual that it can be used as an even more reliable way of identifying a person than a pattern on the skin of fingers.