Why to spend one hour talking about anatomy in a brain mapping meeting? Just because if we don't know geography, we will not understand history, of course. Just as John Furnell said, the man who coined the term physiology, anatomy is for physiology with geography is for history, as we all know. As we all know, the curiosity and the interest of men with the CNS is very, very old, with the boreholes and craniotomies being probably the oldest surgical procedure that was done in a systematized way. Now, if we jump many, many centuries and we come to Renaissance, we see that the father of anatomy still pictured the cortical surface of the brain very chaotically, as did others in his period, as Giulio Cassari, and even Raymond Vissens, the man that described the fibers and described the subcortical central semiovalley. He did show also the cortical surface so chaotically. You see here Silvius, who described the lateral fissure, and we are already in the 17th century, and he said that the gyro had an anatomy similar to the small bowl. Even the great Thomas Willis, although he was very, very interested in cognitive functions as well, in his famous book about anatomy that was illustrated by the famous architect Christopher Wren, did show the cortical surface still chaotically. It was only in the mid-1900s, Louis-Pierre Graciolet, a French anatomist, it's amazing, only 160 years ago that he understood that there is an organization, and a plenitude, as they say, of the cortical surface, and that's what we're going to be talking mostly. Let's start our geography here, putting our glasses. I'll start with some very basic features that are very important. Since the pia mater is extremely attached to the surface of the central nervous system, and the arachnoid is just like an envelope of the whole CNS, we have to understand the psoas and the fissures as extensions of the subarachnoid space. They can be continuous, but they are mostly interrupted, and they can have very different shapes. So we have to understand the psoas and fissures as a space, as an extension of the subarachnoid space. Now, since the psoas and fissures of the brain arise throughout evolution, throughout an unfolding process in order to increase the surface of the brain, which was done three times with this process, the surface of the brain is three times bigger, but since it was throughout this process, always when we have an interruption of the psoas, it's because we have a connection between the gyri. And, of course, they are also continuous along their depth. So we should understand the gyri of the brain not as a very well-defined structure, neurostructure. We should understand them as a region. That's how we should understand the gyri. Another very interesting feature, particularly for us neurosurgeons, is that since this unfolding process took place at the same time evolutionary, as the brain was bending around its center that is given by the thalamus, all the psoas of the supralateral surface and of the basal surface are always taking us to the nearest ventricular cavity. So this is very important for us to understand the architecture and know where we are when we're going through a sulcus. We're always going, or just next to a sulcus, if we're going superior, we are going towards the nearest ventricular cavity. You see here that the posterior part of the middle frontal gyri was removed, and you see that the superior frontal sulcus and inferior frontal sulcus take us naturally towards the ventricular cavity. This is not true for the suicide of the mesial face of the brain, because they are dependent on the development of the corpus callosum. If we have an agenesis of the corpus callosum, you will have the suicide of the mesial face completely disorganized. So if we see laterally, the lateral surface of the brain, of course we see very well the lateral fissure, that it's called the serine fissure, that separates, divides the frontal lobe from the temporal lobe, both of them with two longitudinal, very pretty much well-defined gyri. And if we come back to the serine fissure, we can always see an enlargement of the subarachnoid space that is very variable. And from this enlargement, we have the division of the serine fissure in an anterior part, or a sphenoidal part, and in a posterior or lateral part. And from this point that it's called the anterior serine point, because we have a posterior serine point, from the anterior serine point, we always have an anterior ascending branch and a horizontal branch. And of course they define the triangular part or the inferior frontal gyrus. The inferior frontal gyrus. The inferior frontal sucus is always interrupted. So we have here the pars triangularis, triangular part. Anterior to it, we have the orbital part. And posterior, we have the opercular part. I want to talk very much about the opercular part, because the opercular part always, always, always has the shape of this beautiful U. It's one of the most constant anatomy of the cerebral surface, is this beautiful U. Since it's an U, it's because we always have a sucus in here. And the sucus is always, always, always the precentral sucus. So the precentral sucus always ends inside the pars opercularis. Posterior to it, we have the very two well-defined oblique gyri, the precentral and the postcentral, that are connected inferiorly with the subcentral gyrus. That is delineated anterior by the anterior subcentral, and posterior by the posterior subcentral rami. Both the central sucus and the precentral sucus are not branches from the cervical fissure, because you have this bottom of this U-shaped areas here. So, if we go to surgery, and when you see this, you're seeing a lot of things already, okay? Of course, this is the anterior cervical point. And usually, you have these two small veins getting together here, as I always point. And from here, the more you know, the more you see. And from here, you have the anterior, I mean, the horizontal branch and the anterior ascending branch. So you have to believe in what you know. This is the pars triangularis. So this is the pars triangularis. And this is the orbital part that is always bulging. You want to put your sucker here, your suction tube here. And posteriorly, of course, if this is the pars triangularis, this is the pars opercularis. So if this is precentral sucus, you can make sure this is precentral sucus. Well, if we go most posterior in the posterior region, parietal and occipital region, we see another very well-defined sucus, which is the intraparietal sucus. Intraparietal sucus is always, always continues with the inferior part of the postcentral sucus. Postcentral sucus continues with intraparietal sucus. And it divides the parietal region in a superior parietal lobule and an inferior parietal lobule. The inferior parietal lobule is constituted by the supramarginal and by the angular gyrus. So this is very well-defined. Occipital region in men, in the lateral surface, it's very variable. But as we're going to see in other slides, we always have a superior occipital sucus that is vertical, and an inferior occipital, I'm sorry, inferior occipital gyrus that is vertical along the midline, the peristhetic fissure, and you have the inferior occipital gyrus. Now, coming back to the sylvan fissure, the sylvan fissure always have at the end this ascending part, this posterior, so this is posterior sylvan point, this is posterior ascending part. And posterior ascending part always gets inside the supramarginal gyrus. That's why this is called supramarginal gyrus. Supramarginal gyrus is always a very well-defined gyrus with this shape. Angular gyrus here looks like a horseshoe, but usually doesn't have this very constant shape. So that's why we have talked about the region of the angular gyrus. Now, if we come to the superior temporal sucus, superior temporal sucus interrupted here, but usually is a very deep and continuous sucus, and ends in a point that is posterior to the posterior sylvan point. And here, you have usually a trifurcation. The ascending part of it that separates the supramarginal from the angular, that usually is a branch of the interparietal as well, just as in this case. If you have two branches here, it's because you have a connection. Now you can see, prior to surgery, in your MRIs. But this is the intermediary sucus of Janssen. Intermediary sucus that comes from the posterior end of the superior temporal sucus. And the most distal part of the superior temporal sucus gets inside the angular gyrus. Gets inside the angular gyrus. Just like the sylvan fissure gets inside the supramarginal, the superior temporal sucus ends inside the angular gyrus. So this anatomy, it's in such a way that the superior temporal gyrus will be always continuous with the supramarginal. And the middle temporal gyrus will be always continuous with the angular gyrus. And the inferior temporal gyrus will always be continuous with the longitudinal occipital gyrus. The middle occipital gyrus is much more variable. But the inferior one and the superior one, they are pretty much less constant. If you come back here, you see the anterior sylvan point, the pars triangularis. You always have this segment of the inferior frontal sucus getting inside the pars triangularis. And pars opercularis always this beautiful U, harboring the precentral sucus. That it's always interrupted because all this gyrus longitudinal, they are insected in the precentral gyrus. Central sucus, of course. Postcentral gyrus and postcentral sucus, that it's continuous with the supramarginal. So just by looking at that, you can see very quick that this is the anterior sylvan point. Beautiful U, pars opercularis. So the nidus of this AVM is just in the anterior part of the pars opercularis. And of course, this is precentral sucus. The central lobe in the MRI always looks quadrangular here with the central sucus. Postcentral continues with interparietal. And superior temporal continues with supramarginal. And of course, the superior temporal sucus will get inside the angular gyrus, if we could see better here. Now, if we come to the superior surface of the temporal lobe, we see very well the transverse gyrus of haschel here. All gyri that are inside any sucus are called transverse. This is the biggest transverse gyrus we have. Of course, the haschel gyrus usually is single, but it can be double. And it divides, separates the superior surface of the temporal lobe, also called opercular surface, in two planes. An anterior one, that it's the polar plane, that is very oblique and actually covers the inferior half of the insula. And then we have the temporal plane, that it's flat, triangular, with its apex always looking at the atrium. So, if we see an MRI coronal that has this, the sylvan fissure with this component going down, oblique, is because we are anterior to the haschel gyrus. If we see it flat, it's because we are at the haschel gyrus level, or posterior to the haschel gyrus. Another very interesting and constant feature of the haschel gyrus is that you always have this bulging here. You always have this bulging here, and the post-central gyrus is always, always, always sitting over the haschel gyrus. So, let's see if this is true. You see here the anterior sylvan point, beautiful U, very constant, pars opercularis, pre-central sucus, central sucus, pre-central, post-central gyrus. So, post-central gyrus is always sitting over the haschel gyrus. And this is exactly at the highest level of the squamous suture, if you want to know where it is in regard to the skull. So, that's how radiologists identify the haschel gyrus. They see this bulging here. That's how they see the haschel gyrus. And if you go, you're going always to know that the post-central gyrus is always sitting over the haschel gyrus. So, when you look at an MRI, we try to look for the most common features, and that's one of them. We always have to know where is our lesion in relation to the haschel gyrus. Now, inside the fissure, of course, we have the insula that is covered by the operculum. Why operculum? Because operculum in Latin means curtains. So, the curtains of the insula are covering the insula. Now, the apex of the insula is what is just underneath the anterior semen point, which is, of course, the highest part of the insula. We're going to be talking about how to understand the insular tumors at the end of the lecture, and we'll come back to this. So, when we see the anterior semen point, if we open the fissure, we know that right here we're going to have the apex. Even if it's a little bit flat, we know we're going to be having the apex of the insula, and this is important for our surgical orientation. So, if we remove the curtains of the insula, and we always think about the insula as having a lateral surface, but it has a big anterior surface as well. Of course, this is covered by the frontal parietal operculum and by the temporal operculum, which is only the superior temporal gyrus. Middle temporal gyrus doesn't cover the insula anymore. And the anterior wall of the insula is covered by the posterior orbital gyrus. So, if you remove selectively the posterior orbital gyrus, you expose the anterior surface of the insula. So, we see here the apex of the insula, and anatomy is a lot of definitions. So, by definition, the short gyri of the insula are all these gyri that arise from the apex of the insula. So, this looks long, but this is short because it's arising from the apex of the insula. And then we have usually two, or it can be only one, divided in a Y-shape here superiorly, the long gyri of the insula. And they are separated from the short gyri by the central sucus of the insula. And guess what? The central sucus of the insula is continuous around the corner here with the central sucus of the brain. This is very well organized, central sucus of the brain. Let's see if this is true. Of course, this is precentral, and we have the longitudinal frontal gyri. So, this is central sucus of the brain, continues with the central sucus of the insula. The insula is surrounded by a sucus that used to be called the circular sucus of the insula. But now we call it anterior limiting, superior limiting, and inferior limiting suci of the insula. While the superior and the inferior are very shallow, they are only depressions from the surface of the insula towards the opercular surfaces. The anterior limiting sucus of the insula is very deep, is very deep. It's just like a fissure. You see that here I did not remove the orbital part. The orbital part of the inferior frontal gyrus doesn't cover the insula. So, it's not part of the operculum. So, if we, let me just come back here to show what we got. We're going to be focusing now, enlarging this area here. And if you come here, we see that anterior limiting sucus and inferior limiting sucus, they are interrupted. And when you have an interruption, it's because you have a gyrus going through. And we have this gyrus coming from the apex, going towards the posterior orbital gyrus, which is the transverse gyrus of the insula that goes just anterior to the lemming insula. We call lemming insula this inferior limiting of the insula that has this C-shaped format. So, lemming insula is very deep. Apex is very, very, very superficial. And the apex is just underneath the anterior silver point. To show the anterior short of the insula, I just had to remove the pars triangulares. Pars opercularis, another specimen, also beautiful ewe, precentral sucus, is already covering almost the anterior half of the insula. The anterior limiting sucus of the insula would naturally take us to an anterior recess that is just anterior to the head of the caudate. So, you see how close the depth of the anterior limiting sucus is close to this anterior recess, anterior to the caudate, separated by just some very tiny fibers of the anterior limb of the internal capsule. So, if we can open very widely the silver fissure and expose the superior part of the anterior limiting sucus of the insula, just superior to the apex, we're going to get very easily into the lateral ventricle, anterior horn. Now, if we go inferior here, we're going to get into the ventus triatum area, which is an area that we're going to be showing a lot of dissections shortly. Again, I did remove the pars triangulares. You see the beautiful ewe, pars opercularis, in order to expose just the anterior part of the insula. Posteriorly, we have the haschial gyrus, of course, going towards the atrium. In between, we have the insula. Always remembering that the insula is just the surface. It is just like an external shield or a very well delineated part of the brain that Dr. Rotten called the central core of the brain, which is very important. We'll be coming back to this because it has a lot to do with the insula tumors. While the anterior part of the insula surface is related to the head of the caudate, the posterior part is related with the thalamus more deeply. Of course, we have the haschial gyrus just coming here posteriorly. If you see from above, we can see the very well-defined oblique gyri, that it's the pre-central and the post-central, that are connected to the paracentral lobule, which is our second beautiful U that I want to emphasize here. you see that the central lobe, the so-called central lobe, is just like an ellipse, that is excavated by the central suclus. Anterior to it, we have the superior, the middle, and then the inferior longitudinal frontal gyri. The superior frontal gyrus is very important because, as you know, harbors a lot of tumors and is delineated laterally by the superior frontal suclus. Superior frontal suclus usually is a continuous and very deep suclus, a very primary suclus. Sometimes you'll have a medial frontal suclus that's secondary, shallow, not important at all. The so-called SMA area is more medial, it's not very well defined anatomically, but it's the most posterior and medial part of the superior frontal gyrus. The frontal gyri are always connected to the precentral gyrus. And while it varies the connection between the superior frontal and the precentral, but usually it's more medial. Now this connection here between the biggest frontal gyrus, which is the middle, it's always superficial and we can always see here, and it's very frequent for the gliomas to go through this pathway, as you all know. If we see further back, we always have to look to things that look familiar. You see here the beautiful U, if you see a beautiful U, it's because this is the paracentral lobule. Of course this is central suclus, precentral suclus, superior frontal suclus meeting the precentral here. But if we look back here, there is another important fissure that we always see, that it's the parieto-occipital fissure. Let's see better what is this fissure here. If we see medially, you see the calcane fissure. Of course this is the parieto-occipital suclus or fissure, and this is so deep that you have always this incisor here. So you always have this incisor, and around this incisor you always have this third beautiful U. First, second, the third beautiful U here is what is called the parieto-occipital connection of graciole. It's always there. Of course this is intra-parietal suclus, and when it reaches here, it changes name. It's intra-occipital suclus, also called superior occipital suclus. Of course if this is intra-parietal, of course this is supramarginal, and this is angular. Supramarginal gyrus is the most prominent part, particularly its anterior part of the skull, and it's just underneath the ilium, which is our most prominent cranial point in our parietal bossa here. Here we can see that the occipital region, you always have this vertical gyrus that continues with the cuneus. The superior occipital gyrus is the same piece of brain as the cuneus, just like the superior parietal lobule is the same piece of brain of the precuneus, just has a different name if seen from above or if seen from medially. In inferior, you have the inferior occipital gyrus. The middle occipital gyrus, as I said, is much more variable. In this case, you're seeing very definitely. Now, of course this is calcane fissure. This is parietal occipital fissure. This is calcane fissure. Then we'll be seeing the lingual gyrus here, and this is a very well-defined ring that we have here. Inferior temporal gyrus, inferior occipital gyrus, go around the corner, it continues with the lingual gyrus, just like superior occipital continues with the cuneus, and superior parietal lobule continues with the precuneus. This is a very, very well-organized anatomy. We're not going to spend time very much with the medial region because I want to talk more about the lobar and basal forebrain anatomy that has more to do with the tumors that will be talked here, but of course you have the cingulate gyrus continues with the parahippocampal gyrus, a very well-defined inner ring here. But I want to talk about this region initially. You have the superior frontal gyrus, the medial part of it, that it always continues with the rectus gyrus. The rectus gyrus always is separated from the cingulate to the superior rostral sucus. So it's facing down, superior rostral sucus. And inferior rostral sucus is always inside the rectus gyrus. Now where the superior rostral sucus ends, you have a connection between the cingulate gyrus and the rectus gyrus. Let me tell you, emphasize that the anatomy of the medial surface is very, very, very constant, very constant because it's very old phylogenetically. So you always have these connections here, you're always going to see this in all MRIs and all specimens. Dr. Yasagil called this connection here the cingulate pole. Let's see better this area because it's going to be important for us further on. So you have here the superior rostral gyrus, and you have here the cingulate pole. Behind the cingulate pole, anterior to the anterior commissure, we have three small gyri. The anterior parathyrofactory, posterior parathyrofactory, and paraterminal gyrus. And this is the septal region because particularly the paraterminal gyrus harbors the septal nuclei which are the gateway of all cortical afferences from the cortex towards the hypothalamus. So of course you know that the septal region is very important and tumors will come in here as we're going to be showing at the end. So this is the septal region. Now let's also see better this posterior part, how we can understand better the parahypocampal gyrus. You see here the calcane fissure and anatomy definitions. The parahypocampal gyrus starts just at the proximal part of the calcane fissure. So this is parahypocampal gyrus. This is the cingulate gyrus. It's continuous with the istimus here. So just around the splenium you have the istimus and the istimus will be continuous with the parahypocampal gyrus. So let's enlarge this area. Of course here you see the onchococcus. The onchococcus always have this triangular shape with apex here. But let's enlarge this area here and you can see how deep the calcane fissure is. And you can see that the parahypocampal gyrus is just like the stem of a big tree that its main branch is the lingual gyrus. The lingual gyrus is the main branch that it's pretty much continuous with the parahypocampal gyrus. Of course the istimus is also. You can see the splenium also gets inside here the parahypocampal gyrus. And the precuneus has a contribution coming posterior here and will be also part of this. So the parahypocampal gyrus is a stem of a big tree as you can see here. The onchus has this triangular shape and always when we look at the onchus we have always to think that its anterior half harbors the amygdala and its posterior half harbors the head of hypocampus. And then we have the apex here. Of course you have the head of hypocampus, the body, and the tail of the hypocampus. And immediately you have the superior surface of parahypocampal gyrus which is the subiculum. Why subiculum? Because subiculum means bed and that's where the hypocampus rests and the thalamus rests also. This is why this is called subiculum, the superior flat surface of the parahypocampal gyrus. So you can see here beautifully the head of the hypocampus, the body, and the tail. And we have the amygdala anteriorly to the head but also going superior and covering the head of the hypocampus. We'll come back to this later because this is very important. We're still talking about surface. If we see the orbital face of the orbital part, the orbital face of the frontal lobe, we see the orbital sucus that has this H format, rectus gyrus, lateral orbital, anterior orbital, posterior orbital, that I say that always looks like a Napoleon hat here. And now you know that it's covering the anterior wall of the insula. And you see the lateral orbital gyrus. Of course, it's continuous with the orbital part of the inferior frontal gyrus. We can see the uncus, the rhino sucus that separates the uncus from the rest of the temporal lobe. And if we go more posteriorly, we see the anterior perforate substance that is going to be very important in the second part of this lecture. Anterior perforate substance that has as its medial limit the intermyspheric fissure. Posterior limits both the medial and the lateral stria of olfactory stria. The posterior limit the optic tract. And more lateral limit the liming insula that we're not showing here. Everything that is posterior to the optic tract is posterior perforate substance we're not getting into here. But this is a very important wall of the basal forebrain that will be come back to it. If we go to the temporal basal region, we already know that the inferior temporal gyrus is continuous with the inferior occipital, which goes around the corner. It's continuous with the lingual, that it's continuous with the parahippocampal gyrus. And in between, we have the fusiform gyrus that has this shape not very well delineated in this side. And this is why it's called fusiform. Why? Because the collateral sulcus go from the occipital pole towards the temporal pole here. Not in this case, but very frequently is continuous with the renal sulcus. Rhinal sulcus definition separates the uncus from the rest of the temporal pole. This is polycortex. This is neocortex. But here we have the collateral sulcus. And laterally to the fusiform gyrus, we have the occipital temporal sulcus. And the occipital temporal and the collateral, they always meet. And that's why you have this anterior part of fusiform gyrus that looks like an arrow. We're going to be coming back to this. Now let's see the connections about these main points that we've been talking about. So if we start removing the surface of the brain, of the surface of the supralateral aspect of the brain, the first bundle of fibers that we're going to be seeing that has already been mentioned here in this meeting is the superior longitudinal fascicle. The superior longitudinal fascicle has a very well-defined horizontal portion that runs from mostly inside the middle, underneath the inferior frontal sulcus, towards underneath the supramarginal gyrus, towards the superior temporal gyrus. But this is the horizontal portion, very well-defined. And we have a very well-defined vertical portion as well that comes from the depth of the supramarginal towards the end, the most distal part of the superior temporal. And we have a smaller prolongation of the supramarginal superficial that goes towards the temporal, underneath, inside the superior temporal gyrus. Now, the so-called uncinate fascicle, the problem is that these structures were described by different authors and got different names. But nowadays we understand the arcuate fascicle as the deepest part of the superior longitudinal fascicle, as you can see in this beautiful tautography here by Catani, was just mentioned already in the last lecture here. So it's the deepest part of the superior longitudinal fascicle that it's all this contingent of different fibers, horizontal segment and vertical segment as shown here. If we remove the surface of the insula, of course we are showing now what we call the extreme capsule, that it's nothing more than the subcortical white matter of the insula, just the fibers of the insula. Here we have the superior longitudinal fascicle still there. If we remove a little bit more, we start to see the claustrum together with the so-called external capsule. External capsule, internal capsules are the capsule of the lentiform nucleus, okay? So we're still seeing here the claustrum together with the external capsule, which is giving more with many claustrophobic fibers. And we start seeing some bundle of fibers we see much better, which is the IFOF, inferior frontal orbital fascicle, and the uncinate fascicle we're seeing better. Why I mention this now? Because they are continuous with the external capsule. The uncinate and the IFOF are, they belong to the same layer as the external capsule. If we remove the external capsule, of course we start seeing the putamen here, and you see the corticostriatal fibers that are coming and getting inside here the putamen. Once we remove the rest of the external capsule here, we can see much better the IFOF, and we can see the uncinate here anteriorly. And now we did cut here the vertical part of the superior longitudinal fascicle, and we're seeing a very well-defined group of fibers here that has different layers, and we're going to be seeing that it's covering both the inferior horn, okay? You see the hippocampus down here is covering the inferior horn, and it's covering the atrium. We're going to be seeing that this group of fibers have different layers, and it was called by Joseph Klinger, who made the fiber dissection popular in the 1960s, he called this the sagittal stratum. So let's understand the sagittal stratum as the whole, all the layers of fibers that are coming, that are covering the inferior horn and the atrium. And you see that the IFOF constitutes the fibers that are more superficial here in the sagittal stratum. The uncinate also belong, but they go more anterior towards the temporal pole, as you know. If we remove now the putamen, we're seeing the globus pallidus, and we're actually seeing now the internal capsule fibers. Here's corona, corona radiata, okay, central semiovalli, and when it comes to the level of the lentiform nucleus, it becomes the internal capsule of the lentiform nucleus. Again, you're seeing the IFOF, very well separated, divided from the uncinate, that it's more anterior, part of the sagittal stratum. Now, seeing from superior, we see this very, very important region that we're going to be talking about, and we're going to be coming back at the end of the lecture when we talk about insular tumors, which is called the ventrostreatum area, and by other orders also the anterior perforate substance region, striatum ventral region, or anterior perforate region. What do you see here? See the globus pallidus? You see the anterior commissure running here at its base. This is the posterior part of it. The floor and the anterior wall of this region is the anterior perforate substance itself. The roof is given by the anterior limb of the capsule, and immediately here we have the accumbens. Let's understand better what is the accumbens. The internal capsule was developed throughout a long evolution when the Mamos came. When the Mamos came, the thalamus and the telencephalon developed, and we have to develop the projection fibers as well. So the projection fibers came, but in order for them to develop, they did split the old striatum, the corpus striatum. But they split only the dorsal striatum, because the ventrostreatum, the anterior part, was not split, because as you know, the internal capsule has the shape of a fan towards the peduncle. So the dorsal striatum is separated. Immediately you have the caudate, and later you have the putamen, but the ventrostreatum was left there, and ventrostreatum is pretty much synonym of accumbens, nucleus accumbens. It corresponds to the ventrostreatum. So let me just come back here. So if we come back here, we understand that the medial wall, or the medial part of this important region that we're calling the ventrostreatum region, is the accumbens itself. And since the floor and the anterior wall is given by the anterior perforate substance, of course we have the perforators coming exactly in this area. Let's remove the IFOF and the onsenate fascicle here, and we can see that the perforators, they come mostly anteriorly to the anterior commissure, not posterior. You see that underneath the putamen that would be here, you don't have a lot of vessels coming in here. So this is important, because of course the inferior limiting succus of the insula would be here. If you are more posterior, it's a region that we can still get in, but to get into this region is very difficult because of the perforators here. Let's understand better how to identify these lesions in the MRI, this region in MRI. We see a small lesion here at the base of the caudate, the head of the caudate. Here we see the anterior commissure, posterior the main forniceal, the columns of the fornix, and we see that this lesion is anterior to the anterior commissure here. If we see here, we see the bifurcation of the carotid, we know the anterior perforate substance runs just posterior to the bifurcation to M1 and A1. And we see here the accumbens, caudate, putamen, and the accumbens. And we see that our lesion is just underneath the accumbens. So our lesion is anterior to the anterior commissure, posterior to the anterior perforate substance, and just underneath the accumbens. So this is anterior wall, this is posterior wall. So our lesion is right here, okay, is inside the region that we're talking about. This is important for us to know this region and to identify because unfortunately it's one of the few places that we cannot get in so far. Now let's remove everything that is anterior. We're seeing better the accumbens here, okay, and we're seeing now the anterior commissure. Remember that the IFOF was running here, was the most superficial fibers of the sagittal stratum, and now we are seeing the anterior commissure fibers. Anterior commissure fibers are pretty much what we call the second layer of the sagittal stratum, and they are running just anterior here to the globus pallidus. Here we can see better the anterior commissure fibers, and we are seeing here the head of hippocampus. We're seeing here the amygdala. We're going to be returning to this. Medial extension of the amida ansa peduncularis will return to this shortly. But at this point, I want to emphasize the anterior commissure, anterior commissure fibers going posterior, sort of the second layer of the sagittal stratum. If we detach the anterior commissure and we do a peeling of this most superficial fibers, we can cut, and what can we see now? Let's say another layer, if we can say this, because these layers, of course, they intermingle, they get together, but we see that we have a more well-defined fibers here that coming from somewhere posteriorly, they go anteriorly, and then they go posterior. Of course, this is the optic radiation fibers, okay? And they are the inner layer of the sagittal stratum. And we see here, of course, the anterior commissure. And we see that the anterior commissure runs in a very, very well-defined channel that it's in the base of globus pallidus. And this channel is called channel of gracioli. Here you can see beautiful the accumbens ventros triatum. Anterior commissure passes just posterior to it. You have the head of the caudate, continues with ventros triatum. That would be continuous with the putamen that would be here. If we remove this, if you bring this, you see this beautiful dissection of something that we read, but I never seen. This is a richer dissection. You see that the amygdala covers its anterior and covers a little bit the head of hippocampus, and then extends superiorly towards the globus pallidus. It really connects with the globus pallidus. And you see here this beautiful channel of gracioli. This is an interesting slide, because we can see here the anterior perforate substance intact. And here we have everything dissected. And you see that the accumbens is pretty much at the depth of the olfactory sucus, just superior to what we could call the olfactory trigon. That's where the accumbens is. These are very, very old structures. And you can see here, again, the anterior commissure running through the posterior part of the accumbens and just posterior to what? To the ansa peduncularis. So this is the amygdala. This is the medial extension of the amygdala, ansa peduncularis, which harbors the amygdalo-fugal fibers. Amygdalo-fugal fibers, they go to the hypothalamus, to the thalamus, and to the septal region. And the most superficial fibers of the ansa peduncularis, they go to the septal region, that is in this side. And they are so superficial that they do a ridge in the anterior perforate substance. So this ridge that you can see here is the amygdalo-fugal fibers going to the septal region. And this is what is called diagonal band of broca. That's what I would call. And of course, this is anterior substance that we'll be talking about. Again, we can see here the anterior commissure that we're talking about. And as Miner described, the anterior commissure has an hemispheric part and has an olfactory part. This olfactory part puts together both olfactory systems, showing that the anterior commissure, it was a very, very important commissure for the ancient reptiles. Neuroanatomy is difficult because there are so many structures that were left there through evolution. They were functionally very important in the past, but they are not this important anymore, just like this connection here, this part of the anterior commissure that is beautiful, showing this dissection. And here we can see also the fornix. Most of the fornix goes posterior to the anterior commissure, as you saw in the MRI. But there is a small component of the fornix that goes anterior to the anterior commissure. It's called the precommissural part of the fornix that ends also at the septal region that was removed here. So you always have this anterior commissure going through both components of the fornix. If we go back to the base, let's see again our fusiform gyrus. And a very important feature of the fusiform gyrus is to understand that the fusiform gyrus is the floor of the inferior ventricular cavity. The anterior half, the anterior part of the fusiform gyrus is the floor of the inferior horn. And it's sitting over the pitreous bones mostly, while the posterior part is the floor of the atrium and is already sitting over the tentorium. You see here the collateral sulcus. And you see here the depth of the occipital sulcus, of the occipital temporal sulcus. Inside the fusiform gyrus, we have the inferior longitudinal gyrus that has been mentioned here. And if we remove this, we will expose the ventricular cavity. And at its roof, we'll have the optic radiation fibers. You see that the optic radiation fibers, they arise not only from the lateral geniculate body, but they arise from the whole pulvinar, the posterior part of the thalamus. This is the Meyer's loops. And you see the anterior commissure fibers are a layer that is superior to the optic radiation. This is all part of the sagittal stratum, that Klinger called, that it's the roof and the wall, the lateral wall, of the inferior horn and of the atrium also. These are concepts. Internal capsule is a concept. Sagittal stratum is another concept. Some fibers, like the radiation fibers, they belong both to the internal capsule and to the sagittal stratum. So that's a way to understand. And here you have the lateral mesencephalic sulcus with the medial geniculate body always at the top here. Medial geniculate body is much more well-defined than lateral geniculate, since lateral geniculate can be flat. And here you can understand the lateral geniculate body is pretty much part already of the roof of the inferior horn. So this is an architecture we have in mind. If we remove, we can see better the most superior part of the roof. And what we can see, this dark white matter, this dark matter here, this gray matter, is the tail of the caudate. You see that the tail of the caudate runs along all the roof of the ventricular cavity here in inferior horn. And guess where it's gonna end? It ends also at the amygdala. This is the amygdala. And this is now the posterior extension of the amygdala, which is the stria terminalis, that runs just lateral to the optic tract, which is ending, of course, in the lateral geniculate body here. So you have amygdala, stria terminalis, and then you have here the upper extension of the amygdala that was covering the head of hippocampus that was removed here. And the tail of the caudate will get here and will end also together with the amygdala and together with the globus pallidus, as you can see better here. You see the caudate, you see the head, the body of the caudate, the tail of the caudate that is part of the roof of the inferior horn, and it will merge with the amygdala anteriorly. Of course, more deep here, the amygdala will be continuous with the globus pallidus that is left here, as we already mentioned. So interesting how these structures always get together here. Here we can see the layers that we already talked about. The superior longitudinal fascicle was cutted. We've seen the sagittal stratum. You see how thick is the sagittal stratum. But you see that deep in the sagittal stratum, now we have some very deep fibers that have a different direction, different orientation. What are these fibers? These fibers are arising from the posterior part of the corpus callosum from the splenium. You see what a beautiful dissection here, see? And this is the tapetum fibers. Tapetum fibers are the association fibers that put together the posterior parts of the temporal lobes, and you can see here. And laterally, they run underneath the sagittal stratum. Conceptually, they do not belong to the sagittal stratum. I want also to say a few words about the so-called temporal stem that we use so much in neurosurgery. This term was coined by a radiologist, Horel, along the 1970s, and referred to the stem, to the convergence of the white matter of the fibers of the temporal lobe. So it was a very vague term to start with, and he was talking about all fibers that come here along the inferior limiting sulcus of the insula. You see here a publication by Feindel and Rasmussen after Dr. Painfield, and you see that they already referred to this term, temporal stem, talking about all the fibers that were running along the inferior limiting sulcus of the insula. Now, it turns out that these fibers, we have a lot of fibers there, but I want to emphasize that we have mostly two different components. One is given by the sagittal stratum itself, that you see that it's covering the ventricular cavity, and if we remove this, we can see a different sort of fibers here that I call the peduncular part of the temporal stem, completely different from here. So here would be covering, here, the sagittal stratum would be covering here, and you have here this peduncular part that it's also part of the temporal stem, and of course you have to cut if you want to do an anatomical temporal lobectomy. And the authors diverge, they have different concepts, some authors, if we should consider temporal stem, all this, only this peduncular part, and just a few, only the sagittal stratum posterior along the inferior limiting sulcus of the insula. So, now, when we look at this classification of this slide here, we have to see, other than all this important surgical information that this article show us, but we have to have an X-ray vision to see the anatomy as well. We have to know that under here we'll have the head of the caudate, here we would have the anterior horn, the anterior limb of the capsule, and posterior here we'll have the thalamus, and we will have the third ventricular cavity here, and the body of the ventricle would be a little bit superior to this. So, we know when we see this, we have to think about the central core of the brain, as Dr. Rotem called, and the anterior half related with the head of the caudate, posterior half related with thalamus, the foraminal moro, a little bit anterior to the half of the surface of the insula. And inside it we have the five parts of the internal capsule that we are not going to be talking here for the sake of time. Using anatomy, we can a little bit understand also the extensions of this, unfortunately, very common tumors. So, tumors like to go through natural spaces, of course. So, the lateral part of insular tumors, very commonly what they do, they open this region of the anterior sylvan point. So, it's very common to have this image here when you open at surgery, the insular tumor arising, you see beautiful U, so this is pars opercularis, precentral sucus, and you see that this tumor is arising, opening the anterior sylvan point, that is just anterior to the pars opercularis, here would have the precentral sucus. So, this is very common. Now, for the tumor to come to the frontal operculum, of course, it has to go superior to the superior limiting sucus. And to go towards the temporal operculum, it has to go around the inferior limiting sucus. So, that's what the tumor has to do. And what is this region? This region is the so-called temporal stem. So, in order to reach the temporal operculum, the insular tumor has to go through the temporal stem. Now, if the tumor goes along the uncinate fascicle, or just anterior to the uncinate fascicle, the tumor will have this component that will be mostly subfrontal. Now, what happens if the tumor goes in between the uncinate fascicle and the anterior commissure? It would be getting in here, and where it would be exactly at the striatum ventral region that we'll be talking about. Where do we have the perforators? And then the tumor go and go underneath the accumbens, okay, and can reach what? Can reach immediately the septal region. So, if you understand anatomy, you can understand the roots of this insular tumor, and we'll be ending with this very awful picture. And you can see that the tumor here is in between the anterior commissure, that you can see here. If we see bifurcation, it's because we have the anterior perforate substance, and you see then the tumor is going through the temporal stem the ventral striatum region, or anterior perforate substance region towards the septal region, and of course, it then can reach the other sides and go superior to the septal region as well. So, if we see this, we can think about these spaces, these regions that we'll be talking about. And I end just more six or seven minutes showing everything that I've been showing about the basal forebrain and the temporal mesial region through a trans-servant perspective, okay? So, again, if we remove only the pars triangularis, we're going to be exposing only the anterior part of the insula, namely the most anterior short insula. You see here the pars opercularis with the beautiful U, which is the precentral succous. If we remove the rest of the superior curtain of the insula, we're going to be showing the superior half of the insula. You see here the beautiful haschial gyrus, just posterior. We didn't remove the orbital part because it does not belong to the operculum. It's not covering the operculum. Of course, you have here the apex of the insula, the apical region of the insula. Now, if we remove the superior temporal gyrus, which is the temporal operculum, we can expose, of course, the inferior half of the insula. You see here, again, the haschial gyrus. And if we want to go trans-sylvan to the ventricle, we have to do a small hole just lateral to the inferior limiting succous of the insula and a few millimeters posterior to the lemming insula, okay? And then we will be exposing the ventricular cavity. And if we remove all the neocortical part, what are we left with? We are left with, sorry, we are left with the hippocampus. At the head of hippocampus, you see the amygdala here anteriorly, and the amygdala is standing superiorly. Of course, hippocampus is the internal eminence of the parahippocampal gyrus. So here, you would go towards the choroidal fissure. And here, you would have this peduncular part of the so-called temporal stem that you will have to cut if you want to remove. So you can see here immediately the subiculum, this flat surface of the parahippocampal gyrus, the choroid plexus. Of course, you will have the choroidal fissure here. And this peduncular part that harbors also the upper extension of the amygdala that has to be cut in order for us to remove this hippocampal and amygdala part, now exposing the parapeduncular area. Let's see just to see how it looks into surgery. Here, you see here the lemming insula. You'll see you have a trifurcation of the middle cerebral artery. You have this inferior trunk that it's always running along the inferior limiting succos of the insula. This is also perio-temporal gyrus, opercular surface. And we will be doing our whole just a little bit posterior to the lemming insula, going towards the ventricle. And of course, inside the ventricle, we can see the hippocampus. We can see the subiculum that has this triangular shape. And there, already, the choroidal fissure open. And everything anterior to the inferior limiting point, I mean, anterior to the choroidal fissure, we would have this peduncular part of the temporal stem that then can be cut if necessary. And let's end showing now how we can see the structures inside the insula through this trans-sylvan approach. If we remove the inferior half of the insular surface, we can see, of course, the extreme capsule, which is the subcortical white matter. We see here, if you're seeing gray matter that it's running here, and you know this is the roof of the inferior horn, of course, this, and comes from behind, this has to be the tail of the caudate, of course, going towards the amygdala that was here, as you remember. This is the superior extension of amygdala. This is the tail of the caudate that is coming here. Inferior limiting succos was here. If we remove a little bit more, we can see already the external capsule, and we can see the uncinate fascicle, and we know that the posterior fibers are the eye fall fibers that will be coming to constitute part of the sagittal strata. If we remove a little bit more on the external capsule, we start seeing the putamen a little bit better here. The inferior part will be globus pallidus, is still hidden, still hidden, and we have here the anterior commissure. Uncinate fascicle, eye fall was removed, we start seeing the anterior commissure. Remember that inferior limiting succos was running light right here. If we remove the inferior part of the putamen, we're seeing the globus pallidus, and we know that anterior commissure runs just at its base along the channel of graciolae. Channel of graciolae, anterior commissure already cut it, and you will see gray matters because we are seeing already the accumbens here. You know that the accumbens will be here. So we are right inside the ventral striatum region. If we remove more, we can see the anterior limb of the capsule. This is globus pallidus, channel of graciolae, anterior commissure. Remember that inferior limiting succos is here. That's what you usually expose when you open widely the fissure. And if we remove the anterior limb of the capsule, of course, we see already the head of the caudate that will be merging with the accumbens at this region. And if we look from below, we can see the surface of the insula, the extreme capsule, the claustrum, the external capsule, the putamen, the globus pallidus. And here you can see the upper extension of the amygdala that will merge together with the globus pallidus. And posterior you would have the tail of the caudate that will be coming towards the... It's impressive how this is close to us when we open the sylvan fissure widely and when we deal with these tumors. So I want to finish thanking again the fellows that made this presentation possible, particularly Richard that did these beautiful dissections, Eduardo that put together the 3D. Thank you very much. Thank you.

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