Ok well now that you've actually seen the human brain in the lab. Let's look at some brains sections through Silvius just to recap the structures that we've been viewing. So what I've done is I've entered Silvius and selected sexual anatomy and photographic atlas. And I think what we'll do is we'll start in the coronal plain, so I'm going to simply tap on the coronal plain with the selection of our thumbnail image. And let's now just walk through the brain in the coronal plain, and I have selected the filter set that will colorize components of the deep gray matter as we encounter them. So, let's begin dissection about a few centimeters from the anterior pole of the hemisphere and I just want you to notice that there is no deep gray matter a few centimeters in to the brain. just to remind you that the basal ganglia are set in towards the center of each hemisphere. So if we section back now. another centimeter or two. Now, we begin to see the basal ganglia as they're arranged around the very anterior edge of the internal capsule. We call this the anterior limb. Of the internal capsule. Now notice what we see. In the red coloration, we have the Codate nucleus, which is on the medial side of the internal capsule. And notice how the Codate nucleus bulges outward towards the lateral ventricle. It forms the lateral wall of the body of the lateral ventricle. Now on the lateral side of the internal capsule we have the putamen and again notice it's lateral to the internal capsule which is just starting to make it's appearance here. And again we call this the interior limb of the internal capsule is the exact[UNKNOWN] of streaming. From mainly the cortex that is in the front part of the frontal lobe. Now, not labeled here in Sylvius although we certainly could have here, would be the nucleus accumbens. So let me just highlight that region of the nucleus accumbens. It's basically the ventral part of the striatum. Where the caudete nucleus and the putamen wrap around and come together just inferior to this anterior limb of the internal capsule. So this is roughly where we would find our nucleus accumbance. Now that's one of those nice terms in Neuroanatomy that sort of tells you what it, what it means. this nucleus accumbance is recumbent or reclining upon the septom, which is this medial structure, that divides the walls of the lateral ventricle and, and the inferior part of the posterior frontal lobe. So the nucleus accumbens is the nucleus that's lying down on the septum. Okay, let's go back a section, and at some point, we expect to find the globus pallidus, do we not? And indeed, we see it here, so the globus pallidus is found in green and it, like the putamen, is lateral to these axons of the internal capsule. So here's the internal capsule, so again we have globus pallidus, and putamen, that are found lateral to the internal capsule. And on the medial side we have the collated nucleus. Now, if I can draw your attention towards the center of the section, you'll see, deep into the lateral ventricles, there's some gray matter, that seems to be sticking out at us. I'm referring to these two bulges right there, and right there. Well, hopefully you might have in your mind that, perhaps that's the thalamus. It's medial, it's on the medial side of the internal capsule, it's a little bit posterior. A little bit set back from the large part of the basal ganglia, and indeed that's going to be the thalamus, that we will see as we cut through to our next section. So now, what we find is all the three major components of the basal ganglia that we saw in the last section, caudate nucleus on the medial side of the internal capsule. the putamen, getting smaller but it's still present. And the globus pallidus, also present but getting smaller. And just to be more clear, here's our internal capsule. Now we're getting from the anterior limb into what we call the posterior limb of the internal capsule. And one hallmark of getting into the posterior limb of the internal capsule, is the development of the thalamus on the medial side of the internal capsule. Just in inferior and medial to the caudate nucleus. So this is the thalamus. [SOUND]. The region just inferior and anterior to the thalamus is where we would find the hypothalamus. [SOUND]. Hypo suggesting. Below or inferior to the thalamus and indeed that's where we find it. You maybe wondering about the structure that is is colorized yellow here. This is the amygdala the amygdala is sometimes considered part of the basogaglia but I think it's probably most helpful to you. not to consider it part of the basal ganglia, even though it's included here, and Sylvias under our basal ganglia module for historical reasons. But as we'll get to talk more about the amygdala, you'll see that its functions can largely be differentiated from those that pertain to the basal ganglia. Although for the efficienatos out there who may be studying the basal ganglia and the amygdala, you know that from a different perspective they do indeed have uh,many embryological, histological, and physiological features in common. Well that's a subject for a more detailed course at some other time. But for our purposes let's consider the amygdala separate from the rest of the basal ganglia. Well, just for completeness we'll go back on more section. And what we'll see now is that we are behind now or posterior to the putamen, the globus pallidus, we still have a little bit of cardea nucleus right, because the cardea nucleus is curving around. And we actually see some of it in the temporal lobe just on the dorsal margin of the temporal horn of the lateral ventricle. And that's because this cardea nucleus. Forms this c shaped structure with a long tail that extends into the tempral lobe. S the cut that we've made shows the cardea nucleus in two locations within each hemisphere. Alright now let's go through the same experience only now in the axial plane. So, let's section down, from above. And, if we enter the hemisphere, a few centimeters, below the dorsal aspect of the hemisphere, we are clear above the basal ganglion, so what we see is simply cortex, and the white matter at the center of the hemisphere If we go in one more section. Now, I think it's very clear that the caudate nucleus is on the medial side of the internal capsule. So, here's the caudate nucleus. And what we see is mainly the posterior head, and the body of the caudate nucleus. once again, we see, the thalamus peeking out at us. From the medial side of the internal capsule but set back into the lateral ventricle. You may be wondering where the internal capsule is on this view. The internal capsule is going to come through this white matter in this region, just on the lateral edge of the caudate nucleus. 'Kay, so let's go down one more section, and now we see our three major components of the basal ganglia that we've been featuring in this part of the tutorial. We have the head of the caudate nucleus, and a little bit of the tail, we have the putamen, which is shown here in blue. And we have the globus pallidus, which is colorized here in green. Now the thalamus is located in this region right back there. Okay, now, I realize it's a bit difficult to appreciate the internal capsule here, but this is an important view of the internal capsule. It's running between the head of the caudate nucleus and the putamen and the globus paladus and it's also separating the globus paletus, the putamen and the thalamus. And you'll notice how I'm highligting this internal capsule here. I'm doing it in a way that hopefully brings to light the posterior and the anterior limbs of the internal capsule. So this is the posterior limb of the internal capsule and this would be the anterior limb of the internal capsule. And you may also notice there's a little wisp of white matter that is running right between the two hemispheres in that location. That has nothing to do with the internal capsule. That's actually at a more inferior position. This is the anterior commissure. One of those great commissures. That inter-connects grey matter structures in the cerebral cortex. Okay, so I want you to appreciate now the layout of this deep grey matter relative to this internal capsule because in this one axial slice we see all the important relations that I want you to understand. The globus pallidus and then the putamen are lateral to the capsule, and the caudate nucleus and the thalamus are medial, with the caudate nucleus on the medial side of the anterior limb of the capsule. And the thalamus on the medial side of the posterior limb of the internal capsule. Okay, well I hope you will have a chance to, exercise your knowledge, of this deep gray matter. one way that I would recommend that you do it, is now on your own, if you have a copy of Sylvius, enter our MRI atlas, this is a T1 weighted MRI atlas, of the human brain. And rather than colorizing the brain we've place these small little dots on the brain. And if you select a dot, you will see, opportunity to identify the structure that's labeled. If you click on that structure, now there's information available in a text field over here to the right. So what I would invite you to do if you have Sylvius is to section through the brain. And since this is a MR study of a human brain. We have a much greater density of images. And I think that would be of benefit to you. And I hope you can recognize in this T1 weighted image. Many of the structures that we saw on the lab. In a fresh human brain, and also in Sylvius and what I would invite you to do is to walk through and make sure you can recognize the structures. Not based on how well you can interpret an MR scan, but rather based on your conceptual knowledge of where you expect to find deep gray matter. Relative to the internal capsule and the other important features of the interior of the hemisphere. Okay, well, with a little practice, I'm quite confident that you can acquire these competencies and you will very quickly be navigating your way through sections of the human brain.
