Anatomy of the Cerebral Hemisphere

This is the specimen of cerebral hemisphere. This is the right cerebral hemisphere. This is the superolateral surface. This is the medial surface and this is the inferior surface of the cerebral hemisphere. Now there are three poles in each cerebral hemisphere. The anterior pole, this is the frontal pole. So this is the frontal pole. Behind this is the occipital pole and this is the temporal pole. Temporal pole which is between frontal and occipital. So there are three poles. There are three borders. This border from frontal pole to the occipital pole, this is the superomedial border. So this border is the superomedial border. This is the inferomedial border. This border is the inferrolateral border. The anterior part of the inferrolateral border is known as the supercillary border. This is the supercillary border. Whereas the inferomedial border is divided into two parts. This is the medial orbital border and behind this is the medial occipital border. So anteriorly medial orbital border and posteriorly medial occipital border. So these are the parts of the inferomedial border. We can see along the inferolateral border here this point about 5 cm in front of occipital pole. This is the preoccipital notch. So this indentation is known as the preoccipital notch. Now there are three surfaces. This outer surface, this is the superolateral surface. Then this is the medial surface, whereas the inferior surface is divided into two parts. The anterior part from frontal pole to temporal pole. So this is the orbital part of the inferior surface and this part from temporal to occipital pole is a tentorial part of the inferior surface now to divide the cerebral hemisphere into four lobes we must know two important sulci here we can see there are many grooves these are known as the sulci whereas this elevated portion between the sulci This is known as the gyrus. So there are multiple sulci and gyri on the surface of cerebral hemisphere. The most important of the sulcus is this one which is running downwards and forward uninterrupted. This sulcus is the central sulcus. The central sulcus is mainly seen on the superolateral surface. and a part of the central circus can also be seen here on the medial surface. So this is the upper part of the central sulcus. From here it runs downwards and forwards. So here it runs downwards and forwards. So this is the central sulcus and it tends at the upper part of another sulcus which is this one. So this sulcus here is a posterior ramus of lateral sulcus. The lateral sulcus is another sulcus which has three parts or three rami coming from the stem. So this is the stem of lateral sulcus. The biggest of the ramus which is going posteriorly, this is the posterior ramus of lateral sulcus. And there are two short rami. one going in front this is the anterior horizontal ramus of lateral sulcus and the other one is the ascending ramus of lateral sulcus so these are the parts of the lateral sulcus now there is another sulcus present on the medial surface This sulcus here near the occipital pole, this is the paritooccipital sulcus. This sulcus along with another sulcus, this is the calcarein sulcus, form a Y-shaped sulcus. So this is calcarein sulcus and this is the paritooccipital sulcus. We can see the paritooccipital sulcus mainly on the medial surface. but a small part of parietooccipital sulcus can also be seen on the sucralateral surface here. So if we draw an imaginary line from the upper part of parietal sulcus up to the preoccipital notch, so this is the preoccipital notch, so this is the first imaginary line from parietooccipital sulcus up to the preoccipital notch. So this is the first imaginary line and the second imaginary line we just extend the posterior end of the posterior ramus of lateral sulcus behind until it meets the first imaginary line. So this is the first imaginary line from the paritoxipital sulcus up to preoccipital notch. and the second imaginary line from the posterior end of posterior emers of lateral circles we draw behind until it meets the first imaginary line. So the part of the lobe which is behind this first imaginary line, so this is the occipital lobe, then the part of the lobe which is above the posterior emers of lateral circles but in front of the central sulcus so this lobe is the frontal lobe of the brain so this is the frontal lobe then the part of the lobe between central sulcus and the first imaginary line and below it is limited by the second imaginary line so this lobe is the parietal lobe whereas the lobe which is inferior to the posterior amos of lateral sulcus up till the first imaginary line So this is the temporal lobe of the cerebrum. So these are the four lobes. How we divide each cerebral hemisphere into four lobes. So this is the frontal lobe. This is the parietal lobe. This is the occipital lobe. And this is the temporal lobe. Now in front of the central sulcus. This is the central sulcus. In front of it there is the precentral gyrus. This is precentral gyrus and in front of it there is a precentral sulcus. Similarly behind the central sulcus this is the postcentral gyrus behind which this is the postcentral sulcus. Now in the frontal lobe we can see in front of the precentral sulcus there are the superior frontal sulcus and this is the inferior frontal sulcus so there are three gyris superior frontal gyrus middle frontal gyrus and this is the inferior frontal gyrus So superior frontal sulcus and inferior frontal sulcus divide into three gyri, superior, middle and inferior. In the inferior frontal gyrus we have seen this is the ascending ramus of the lateral sulcus and there is a horizontal anterior horizontal ramus of lateral sulcus. So the part of inferior frontal gyrus between these two rami is known as parsed triangularis behind this ascending ramus this part is known as pars opercularis and the part which is inferior to the horizontal ramus this is the pars orbitalis so these are the three parts of inferior frontal gyrus pars orbitalis pars triangularis and pars opercularis coming to the parietal lobe you There is a transverse sulcus which is known as the intraparietal sulcus above which this is the superior parietal lobule and below is the inferior parietal lobule. Then there is one important sulcus near the occipital pole which is known as the this sulcus is known as the lunate sulcus near the occipital pole this is the lunate sulcus. In the temporal lobe this is the superior temporal sulcus and this is the inferior temporal sulcus so there are three gyri superior temporal gyrus middle temporal gyrus and inferior temporal gyrus now coming to the medial surface this is the corpus callosum just above corpus callosum this is the callosal sulcus In the callosal sulcus we can find anterior cerebral artery and there is a layer of gray matter here known as inducium griseum. Above this, this is the cingulate gyrus. So this is the cingulate gyrus and above it this sulcus here is the cingulate sulcus. So this sulcus is the cingulate sulcus. Between cingulate sulcus and callosal sulcus is the cingulate gyrus. Near the occipital pole we have seen two sulci one is the paritoxipital sulcus here and the other one is the calcarein sulcus. Between the two sulci this wedge shaped area this is the cuneus so this is known as cuneus and the gyrus below the calcarein sulcus so this gyrus is known as lingual gyrus whereas the gyrus in front of paratoxibidal sulcus is known as precuneus. So this is the precuneus. Also we have seen there is a part of central sulcus. This is a part of central sulcus extending on the medial surface. So the gyrus which is around the central sulcus on the medial surface. So this gyrus is known as paracentral lobule which has two parts. One anterior part of paracentral lobule and other is a posterior part of paracentral lobule and behind paracentral lobule is a precuneus so this is the precuneus this is the cuneus and this is the lingual gyrus in the whole gyrus which is in front of the paracentral lobule this gyrus is known as the medial frontal gyrus so this gyrus here is a medial frontal gyrus So these are the sulcaic area on the medial surface. Now coming to the inferior surface. So this is the inferior surface in which the anterior part this is the orbital surface. This is the orbital surface. This is the olfactory area. This is the olfactory bulb and olfactory tract. So the sulcus in which this olfactory tract is located. So this sulcus here we can see this sulcus is the olfactory sulcus. So this is olfactory sulcus and the gyrus which is just medial to it. So this gyrus is known as gyrus rectus. Whereas lateral to this olfactory sulcus the orbital part is divided into four gyri by an H-shaped sulcus this H Shaped sulcus is known as orbital sulcus. So there are four gyri. This is anterior orbital gyrus. This is posterior orbital gyrus. This is medial orbital gyrus and this is lateral orbital gyrus. On the tentorial surface, this is the tentorial surface. This sulcus, very important sulcus here is a collateral sulcus. So this is the collateral sulcus. and the sulcus which is just lateral to it is known as the occipitotemporal sulcus so there are three gyri this gyrus medial to collateral sulcus so this is the parahippocampal gyrus parahippocampal gyrus this parahippocampal gyrus will continue behind with the lingual gyrus and in front this part is known as the uncus So this is the uncus. Between collateral sulcus and occipitotemporal sulcus will be medial occipitotemporal gyrus and laterally will be lateral occipitotemporal gyrus. Also the uncus is separated from temporal pole by a sulcus which is known as renal sulcus. So there there will be renal sulcus which separates uncus from the temporal pole. So this completes our main Sarkai and Chiro on the cerebral hemisphere.

This is the specimen of cerebral hemisphere. This is the right cerebral hemisphere. This is the superolateral surface.

This is the medial surface and this is the inferior surface of the cerebral hemisphere. Now there are three poles in each cerebral hemisphere. The anterior pole, this is the frontal pole. So this is the frontal pole. Behind this is the occipital pole and this is the temporal pole.

Temporal pole which is between frontal and occipital. So there are three poles. There are three borders. This border from frontal pole to the occipital pole, this is the superomedial border. So this border is the superomedial border.

This is the inferomedial border. This border is the inferrolateral border. The anterior part of the inferrolateral border is known as the supercillary border. This is the supercillary border.

Whereas the inferomedial border is divided into two parts. This is the medial orbital border and behind this is the medial occipital border. So anteriorly medial orbital border and posteriorly medial occipital border.

So these are the parts of the inferomedial border. We can see along the inferolateral border here this point about 5 cm in front of occipital pole. This is the preoccipital notch. So this indentation is known as the preoccipital notch. Now there are three surfaces.

This outer surface, this is the superolateral surface. Then this is the medial surface, whereas the inferior surface is divided into two parts. The anterior part from frontal pole to temporal pole. So this is the orbital part of the inferior surface and this part from temporal to occipital pole is a tentorial part of the inferior surface now to divide the cerebral hemisphere into four lobes we must know two important sulci here we can see there are many grooves these are known as the sulci whereas this elevated portion between the sulci This is known as the gyrus. So there are multiple sulci and gyri on the surface of cerebral hemisphere.

The most important of the sulcus is this one which is running downwards and forward uninterrupted. This sulcus is the central sulcus. The central sulcus is mainly seen on the superolateral surface.

and a part of the central circus can also be seen here on the medial surface. So this is the upper part of the central sulcus. From here it runs downwards and forwards.

So here it runs downwards and forwards. So this is the central sulcus and it tends at the upper part of another sulcus which is this one. So this sulcus here is a posterior ramus of lateral sulcus. The lateral sulcus is another sulcus which has three parts or three rami coming from the stem.

So this is the stem of lateral sulcus. The biggest of the ramus which is going posteriorly, this is the posterior ramus of lateral sulcus. And there are two short rami. one going in front this is the anterior horizontal ramus of lateral sulcus and the other one is the ascending ramus of lateral sulcus so these are the parts of the lateral sulcus now there is another sulcus present on the medial surface This sulcus here near the occipital pole, this is the paritooccipital sulcus. This sulcus along with another sulcus, this is the calcarein sulcus, form a Y-shaped sulcus.

So this is calcarein sulcus and this is the paritooccipital sulcus. We can see the paritooccipital sulcus mainly on the medial surface. but a small part of parietooccipital sulcus can also be seen on the sucralateral surface here.

So if we draw an imaginary line from the upper part of parietal sulcus up to the preoccipital notch, so this is the preoccipital notch, so this is the first imaginary line from parietooccipital sulcus up to the preoccipital notch. So this is the first imaginary line and the second imaginary line we just extend the posterior end of the posterior ramus of lateral sulcus behind until it meets the first imaginary line. So this is the first imaginary line from the paritoxipital sulcus up to preoccipital notch. and the second imaginary line from the posterior end of posterior emers of lateral circles we draw behind until it meets the first imaginary line. So the part of the lobe which is behind this first imaginary line, so this is the occipital lobe, then the part of the lobe which is above the posterior emers of lateral circles but in front of the central sulcus so this lobe is the frontal lobe of the brain so this is the frontal lobe then the part of the lobe between central sulcus and the first imaginary line and below it is limited by the second imaginary line so this lobe is the parietal lobe whereas the lobe which is inferior to the posterior amos of lateral sulcus up till the first imaginary line So this is the temporal lobe of the cerebrum.

So these are the four lobes. How we divide each cerebral hemisphere into four lobes. So this is the frontal lobe. This is the parietal lobe.

This is the occipital lobe. And this is the temporal lobe. Now in front of the central sulcus.

This is the central sulcus. In front of it there is the precentral gyrus. This is precentral gyrus and in front of it there is a precentral sulcus. Similarly behind the central sulcus this is the postcentral gyrus behind which this is the postcentral sulcus. Now in the frontal lobe we can see in front of the precentral sulcus there are the superior frontal sulcus and this is the inferior frontal sulcus so there are three gyris superior frontal gyrus middle frontal gyrus and this is the inferior frontal gyrus So superior frontal sulcus and inferior frontal sulcus divide into three gyri, superior, middle and inferior.

In the inferior frontal gyrus we have seen this is the ascending ramus of the lateral sulcus and there is a horizontal anterior horizontal ramus of lateral sulcus. So the part of inferior frontal gyrus between these two rami is known as parsed triangularis behind this ascending ramus this part is known as pars opercularis and the part which is inferior to the horizontal ramus this is the pars orbitalis so these are the three parts of inferior frontal gyrus pars orbitalis pars triangularis and pars opercularis coming to the parietal lobe you There is a transverse sulcus which is known as the intraparietal sulcus above which this is the superior parietal lobule and below is the inferior parietal lobule. Then there is one important sulcus near the occipital pole which is known as the this sulcus is known as the lunate sulcus near the occipital pole this is the lunate sulcus.

In the temporal lobe this is the superior temporal sulcus and this is the inferior temporal sulcus so there are three gyri superior temporal gyrus middle temporal gyrus and inferior temporal gyrus now coming to the medial surface this is the corpus callosum just above corpus callosum this is the callosal sulcus In the callosal sulcus we can find anterior cerebral artery and there is a layer of gray matter here known as inducium griseum. Above this, this is the cingulate gyrus. So this is the cingulate gyrus and above it this sulcus here is the cingulate sulcus. So this sulcus is the cingulate sulcus. Between cingulate sulcus and callosal sulcus is the cingulate gyrus.

Near the occipital pole we have seen two sulci one is the paritoxipital sulcus here and the other one is the calcarein sulcus. Between the two sulci this wedge shaped area this is the cuneus so this is known as cuneus and the gyrus below the calcarein sulcus so this gyrus is known as lingual gyrus whereas the gyrus in front of paratoxibidal sulcus is known as precuneus. So this is the precuneus. Also we have seen there is a part of central sulcus. This is a part of central sulcus extending on the medial surface.

So the gyrus which is around the central sulcus on the medial surface. So this gyrus is known as paracentral lobule which has two parts. One anterior part of paracentral lobule and other is a posterior part of paracentral lobule and behind paracentral lobule is a precuneus so this is the precuneus this is the cuneus and this is the lingual gyrus in the whole gyrus which is in front of the paracentral lobule this gyrus is known as the medial frontal gyrus so this gyrus here is a medial frontal gyrus So these are the sulcaic area on the medial surface.

Now coming to the inferior surface. So this is the inferior surface in which the anterior part this is the orbital surface. This is the orbital surface.

This is the olfactory area. This is the olfactory bulb and olfactory tract. So the sulcus in which this olfactory tract is located.

So this sulcus here we can see this sulcus is the olfactory sulcus. So this is olfactory sulcus and the gyrus which is just medial to it. So this gyrus is known as gyrus rectus. Whereas lateral to this olfactory sulcus the orbital part is divided into four gyri by an H-shaped sulcus this H Shaped sulcus is known as orbital sulcus.

So there are four gyri. This is anterior orbital gyrus. This is posterior orbital gyrus.

This is medial orbital gyrus and this is lateral orbital gyrus. On the tentorial surface, this is the tentorial surface. This sulcus, very important sulcus here is a collateral sulcus. So this is the collateral sulcus. and the sulcus which is just lateral to it is known as the occipitotemporal sulcus so there are three gyri this gyrus medial to collateral sulcus so this is the parahippocampal gyrus parahippocampal gyrus this parahippocampal gyrus will continue behind with the lingual gyrus and in front this part is known as the uncus So this is the uncus.

Between collateral sulcus and occipitotemporal sulcus will be medial occipitotemporal gyrus and laterally will be lateral occipitotemporal gyrus. Also the uncus is separated from temporal pole by a sulcus which is known as renal sulcus. So there there will be renal sulcus which separates uncus from the temporal pole.

So this completes our main Sarkai and Chiro on the cerebral hemisphere.

Transcript for:Anatomy of the Cerebral Hemisphere

Transcript for:
Anatomy of the Cerebral Hemisphere