Understanding Brain Structure and FunctionCH15

Hello everyone, this lecture is on the brain, chapter 15. So there are a couple notes for this. One, if you haven't finished watching the rest of the nervous system lecture, I highly recommend finishing that first. The reason is that we build on our understanding of the nervous system and we apply that to the brain. So make sure you check that out first. Another thing is that as we go through, we're going to learn a couple new definitions. You might remember that I've kind of been making a big deal about what a nerve is and the definition of a nerve. We talked about collection of soma in the PNS. So we're going to actually see that there are alternative definitions for these same kinds of structures but in the CNS. So we're going to see a new name for a bundle of axons in the CNS specifically and we're going to see a new term or name for a bundle of soma in the CNS. Another thing to note is that as we go through the brain lecture you're going to find that there's going to be redundancy in terms of where we're looking at on the brain for structure and function. So as we've been going throughout the course, you may note that I've been identifying structure and function independently of one another, so you have an understanding of both. Now, the cerebrum is what we think about most when we draw the brain. And so that's what I'm drawing here. Not the best version, but it will do. And what I'm going to be drawing for this brain and again on this brain, specifically the cerebrum, is two things, the structure and the function. To help us keep track, I'll go ahead and draw the structure and all of the structural components in black. And then for the function, I'll go ahead and write all of those in blue. First and foremost, the brain is about three pounds. And if you imagine taking that open cranial cavity, imagine removing the brain, taking that cranial cavity and pouring in a liter of soda, which I know sounds super weird, but that's about the volume that you have within your cranial cavity to contain the brain. So the brain itself is about the volume of a liter of soda. Now when we talk about the brain being able to receive and process information, let's associate that back with our understanding of the nervous system. When we have information that we're receiving, we're receiving that information from the PNS, or our peripheral nervous system. When that information comes from the peripheral nervous system and is received by the CNS, our central nervous system, that as a reminder is going to be our sensory division of the nervous system. Alternatively, when the brain processes and then sends out responses, that sending out of the responses is associated with the motor division of the nervous system. So we're going to receive information to the central nervous system, that's our sensory, and then we're going to process, decide how we want to respond with our brain, send that information back out and how we want to respond, and that's going to be our motor division. Now as far as the visual organization of the brain, you're going to notice in the slides coming up that I have done a lot of color coding to help you to keep track of what's what. First and foremost here you're seeing that in green we have the cerebrum. The cerebrum is what I just started to draw on the word document so we can keep track. This is what we normally associate with the majority of our brain, so it's the largest region. And so with that we have our frontal lobe, temporal lobe, parietal lobe, occipital lobe, and also one that you can't see right here because it's deep is called the insula. We're going to see that a little bit later. You also have the diencephalon. The diencephalon is going to be made up of a couple different thalmi. Now when I say thalmi, that is plural for thalamus. Our thalamus is one structure, and you can't really see where it's pointing, but it's right here in the middle, okay? And then on top and below, we have hypo below, and let's see, do I see a label for it? I don't see it, and that's okay. We have an epithalamus, epi above the thalamus as well. So we have our epithalamus, the thalamus, and then we have our hypothalamus. So those are all components of the diencephalon. For our brain stem, I like to think of the brain stem and stem as the stem of a flower. So this would be the actual stem component where maybe the cerebrum would be the flower component of the flower. But in purple you can see the mesencephalon. It's hard to see where this is pointing, but our mesencephalon is pointing to right here. Our pons is right here, and then we have our medulla oblongata, and those are all part of the brain stem. We finally have the final major region of the brain which is the cerebellum. If the cerebrum is the largest component, think of cerebellum like a baby brain or a mini brain. So the cerebellum is right here. Now this view that we're looking at is a lateral view, but more specifically in order for us to see these inner structures like the diencephalon, the inside of the cerebellum as we're seeing it here, we're actually only looking at one hemisphere of the brain. Now when I say hemisphere, we have two hemispheres. We have a left and right. And so we would be able to do a dissection right down the middle of those two hemispheres. If we looked inside, this is what we would see. Where would I have to dissect? Where would I be looking? Well, we're going to find that there's a special fissure, which is an invagination called the longitudinal fissure. And that fissure is kind of the marking point between the two hemispheres of the brain. So we're going to see that structure later. If we did our dissection right down that line, that's how we'd be able to see all of these inner structures. Keep that in the back of your mind. All right, this particular slide and the slide that follows, you're seeing here, these two slides are associated with a level three objective. Now what you want to be able to do is take a brain region, and these are the regions that we just talked about, and associate that brain region with the primary brain vesicles. The primary brain vesicles are all right here. And also with the secondary brain vesicle. Those are all of the ones right here. I am going to do a separate mini video to help you to decipher this because sometimes it's a little confusing for students and I'll color code it. but it takes a little bit of time to walk through that so I'm going to do that in a separate little mini video that I'm going to record after this one. Okay, as far as the regions, the primary brain vesicles and the secondary brain vesicles associated with the brain regions, this slide right here walks you through specifically the secondary vesicles. So what you're going to see listed first is for instance the telencephalon. That is going to be the secondary vesicle for the cerebrum. So let me just walk you back here really quick so you can see. Here's our telencephalon, which is our secondary brain vesicle and that's for the cerebrum. Now when I say brain vesicles and primary and secondary brain vesicles, these are associated with embryonic development. So our mature regions of the brain are the ones that we've already covered, the cerebrum, diencephalon, brain stem, cerebellum. But these are the structures that are going to develop through our embryonic development to help us to make these mature regions. So again I'll do a recording for these two slides coming up in a little bit. All right so first up is cerebrum, one of our first main regions. What I want you to notice at the top of the slides as well to help you to follow along, I've actually incorporated the primary and secondary brain vesicles to help you with this level three objective. So just note that if you see these arrows at the top of a major region, that's to remind you of the primary and secondary brain vesicles that lead to this mature region. So coming back to the cerebrum, what are we going to have here? Well, conscious thought, so our ability to actually have the idea of conscious thought and our ability to have function. Now when we talk about this, we're going to find that there's special functional regions that allow for these certain things. For instance, voluntary motor. You might remember me talking about this when we talked about the divisions of the nervous system. So it's our ability to control skeletal muscle. Also visual. We're going to find that there's regions within the cerebrum that allow for our ability to see or to process vision. And auditory. The same thing, but with hearing. Now when we talk about these areas, what I want you to notice here is We're instead of looking at a lateral view, last time we were actually looking from the side, so I'm just drawing an arrow, and if we had dissected right down the middle like this, we dissected right down the middle like this and removed one of those hemispheres, we were looking at the inside, so we were looking at it from this side. So that was a lateral view that we're looking at. However now, let me see if I can get rid of these, now it's as if we took a coronal plane and we sliced right down the middle. And so now what we can see is if we're looking, imagine that maybe the person's eyeballs would be in the front here. There you go. This would be the kind of view that we're looking at. Okay, so maybe an anterior view and from a coronal section. Now there's a couple different things I want you to notice. Here's our gray matter and here's our white matter. Okay, so when it comes to the gray matter, I want you to notice that that's all along the most superficial part of the cerebral. Okay, so all of this is gray matter. As a reminder, our gray matter is a collection of soma. And specifically here, we're looking at within the CNS. Now, when I talk about a collection of gray matter or collection of soma within the CNS, here comes our definition. Do you guys see this cerebral nuclei? Nuclei is plural for nucleus. And a nucleus is how we define or our term for defining a collection of soma in the CNS. So let me go ahead and erase this guy really quick. So a nucleus is a collection of soma in b c n s okay alternative to that in the peripheral nervous system was a ganglion So if we're talking about it in a collection of soma in the PNS, we say ganglion. If we're talking about a collection of soma in the CNS, we call it a nucleus. And if we say cerebral nuclei, that is plural. That means there's multiple regions of these. The other definition I want to make you aware of now is a tract. A tract is essentially the CNS version of a nerve. So if you might remember, a nerve is a collection of axons in the PNS. Same thing here but in the CNS. So a tract is a of the axon in the CNS. So make sure you can compare and contrast those definitions. All right, so coming back to our little drawing here, just drawing your attention to the outside. So where we see that it's darker in the gray matter, that area is actually called the cerebral cortex. Okay, so everywhere that you're seeing this dark region here, that is the cerebral cortex. It's just this superficial area. Okay, so the cerebral cortex is a superficial gray matter. We then have the white matter, and so that's all of this lighter colored part right here. Okay, so all the white matter, with the exception of these dark regions that you're seeing. These darker regions right here are also going to be... collections of soma. And so we actually call those, the deepest there, those are the cerebral nuclei. So those little dots that I made are on the cerebral nuclei. Ventricles are entirely separate. We have fluid flow to provide fresh nutrients to remove waste from the brain. And that fluid region, think of it almost like a little river running through the brain, that's the ventricle. So that's an entirely different structure that we'll talk about later. All right. Finally, for this slide, something I want to introduce. is gyri, sulci, and fissures. Now gyri is plural for gyrus, so if we talk about just one, singular is gyrus. Sulci is plural for sulcus, so you'll often hear me talking about the sulcus, and fissure is just the original version for that, so that one's nice and easy. Now each of these is slightly different. Sometimes you'll see sulcus and fissure used interchangeably specifically for certain structures. So I just want to draw your attention to that now. If you see me use sulcus or fissure for something and in maybe online or in your book, you see sulcus or fissure used alternatively. It's just that they're both used interchangeably for certain structures. So don't let that get you don't get too hung up on that. But let's go ahead and define these first. So when we talk about a gyrus. is a bump of matter. So this will actually be something that actually protrudes or something that you could feel as kind of a bumpy region. So for instance, if I was talking about a big bumpy region, it wouldn't be quite this one. But this would be an example of kind of a bump that I'm talking about when I talk about a gyrus. We're going to see that there is going to be a big gyrus that we're going to associate with, with sensory. and there's going to be a big gyrus that we associate with motor. So we're going to talk about that next. When it comes to a sulcus, a sulcus is a small invagination. kind of coming off the page here so let me write it over here and I'm going to eventually erase this leader so we have the room but invagination okay or a groove so we're going to see that there's different sulci that are going to be present and that's going to be smaller than our next structure which is going to be our fissure a fissure is a deep invagination So earlier I told you about our longitudinal fissure, which would separate the two hemispheres of the brain. That longitudinal fissure is a really, really deep invagination and so deep that it's almost like somebody took a knife and kind of went through that area. So it's nice and deep. Okay, so a gyrus is a bump, a sulcus is a small groove or invagination, and a fissure is a deep groove invagination. So from this view, just a couple things you can see. Right here, if you see where I'm pointing, that's actually going to be the longitudinal fissure. So let's do it in color. So right here, this is our longitudinal fissure. And we're also going to see that there are different structures such as the lateral sulcus right here. And here's another lateral sulcus, so we'll be able to see those a little bit later as well. All right, so first focusing on the gray matter. The gray matter itself, like I mentioned before, there's two areas where we're going to have a collection of soma. Now I told you that's what's going to be most abundant, which is going to provide for the color that we're going to see, but it's not the only thing that we would see. So let me just show you right here for gray matter. That includes our cerebral cortex, which is the superficial region right here, and our deep cerebral nuclei, which are those that are redox-rich right here. So as I mentioned, collections of soma. So we have our motor or interneuron soma. Okay. And we also are going to have dendrites, teledendria, and myelinated axons. Now again, what's going to be most abundant is the soma to give its color, but we do have some other structures there too. Our white matter, which is kind of sandwiched in between the deep cerebral nuclei and the cerebral cortex. That is going to be a collection of axons in the CNS. And so that's what you're seeing here is mostly myelinated axons in the white matter. Alright, so we are looking at the cerebrum. So if we look at the cerebrum, there are two cerebral hemispheres. Okay, so we have our left cerebral hemisphere and we have our right cerebral hemisphere. Notice that they pretty much look the same, at least how they're depicted, and if you looked at a brain and you did a dissection, they would look pretty similar as well. Here is the structure that I keep trying to mention. This is our longitudinal fissure. Okay, so it's that deep invagination that you're seeing right in between the two hemispheres. The connections between the two hemispheres are called tracts. Let's remind ourselves, tracts are defined as a collection of what? Can you remember? They are a collection of axons in the CNS. Okay, so that's going to help us to make connections between the two hemispheres. We also have one really large tract that we're going to see and that's called the corpus closum and I'll draw your attention to that later. That is our largest tract and we're going to see that it's really white and really prominent, kind of right deep. and central to the cerebrum. Okay, so let me erase this. This is just a lateral view, again, what we saw before. Here's that corpus callosum. We were just talking about all of this that you're seeing right here. That's our corpus callosum, okay? And so as a reminder, that is a tract, and that is going to help us to have connection points between the neurons in one hemisphere versus another. All right, there are some caveats to the brain. One of the caveats being that even though they look similar to one another and anatomically might look identical, they are not functionally identical, meaning that we're going to have some functional regions that exist on the left hemisphere and not on the right. And I'm going to help you to decipher those as we go through. There are some regions that overlap in their function, meaning that we can have two regions, maybe one in the left and one in the right, and they both do the same thing. So there's also functional overlap as well. And then what you've probably heard before, which is super weird, that our right cerebral hemisphere controls the left side of our body and the left cerebral hemisphere controls the right side of our body. So try not to think too much about that as we're going through it, but it's kind of amazing you can think about the brain using the brain and respond. So these are the caveats associated with the brain. All right, let's first focus on the cerebrum. And so when we talk about the lobes of the cerebrum, With the exception of the insula, like I've mentioned before, these should be comfortable for you based on the cranial bones that you studied for the previous lab components. So all of these are going to be anatomically distinct lobes of the brain that are going to be deep to the cranial bones that you associated with them previously, except for what's called the insula. So let me just take a step back here and start to define these. So we have our structure first okay so when we're looking at these different regions our frontal lobe here okay our temporal lobe is right here our parietal lobe is here We have, do you guys remember what's back here? Eyes in the back of your head. Occipital lobe. That will actually become important when we talk about the function of the occipital lobe. And then the final one, the insula, is actually in here. So if we were to actually kind of separate the frontal lobe from the temporal lobe and peek inside, that's where we would find the insula. Okay. So that's the insula right there. And that's going to be our final lobe. So. frontal lobe is what's being represented here in blue so you can see the frontal lobe this is our anterior lobe which makes sense if you think about where your frontal bone is and what we're going to find is some different structures that are going to help us to define where the frontal lobe is located first and foremost we're going to have what's called our lateral sulcus i started to draw this on the other image but this line right here this dark line that is our lateral sulcus We also have our posterior border for the frontal lobe and that is our central sulcus. If you look at this dark line right here, that is our central sulcus. I wish I could avoid those lines, I'm sorry you guys. Okay, now when we say that we have the feature the precentral gyrus, I'm going to show this to you on my other drawing as well, but here let me just show you again is the central sulcus. As a reminder, a sulcus is a tiny invagination. A gyrus is a prominent bump. It's a bulge on the brain. So I'm going to draw where that would be. Okay, all of this region here that I'm drawing with, that is where the precentral gyrus would be. Pre means before, and it's before the central sulcus. So it's called a precentral gyrus because it's a bump. or bulge of the brain that's before the central sulcus. Okay, so that's the region that we're talking about right there. We're also going to find going forward that we have different functional areas. So we're going to come back to the functional areas later. We're going to find that there is our voluntary motor, which will be associated with our precentral gyrus. So we'll come back to that. And as well as our ability to control the muscles for speech. We're also going to find that those functional regions are in the frontal lobe as well. And so here what we're seeing This structure right here is actually going to be our lateral sulcus. That's what I would open up and try and kind of dissect out or that location I try and dissect out if I was trying to get to the insula. And then right here over the parietal lobe, so I'm going to move the parietal lobe out of the way just so we can move it back a little bit, we would have this structure right here. This is an invagination. We call this invagination the central sulcus. And that central sulcus has a bulge in front of it. And that is called the precentral gyrus. Let me just add back our parietal lobe back here so we don't confuse it. All right. Next up is our parietal lobe. These black... it's like x marks the spot so when you see the x is just showing where the lobe is the parietal lobe here is shown in yellow our borders anteriorly is again our central sulcus which we already defined what we're finding is that the lateral sulcus doesn't run all the way through to find that border and that's why you're seeing these little dots so it doesn't go all the way through but it's part of the border it's a lateral sulcus if you were to track the lateral sulcus on a brain model with your finger and just continue to work your way back you'd be able to define the rest of the border The other border that we're going to see is one that we haven't defined yet, which is called the parietooccipital sulcus. Again, as a reminder, a sulcus is a small indagination. When we say parietooccipital, that is going to be a sulcus between the parietal lobe and the occipital lobe. So think about where you might find that. Do you remember where the occipital lobe is? It's right here. Okay. And so right here where my little cursor is, this would be my parietooccipital sulcus. Okay, what we're going to find within the parietal lobe is another bulge of brain matter. Okay, so I want you to notice I'm drawing like I did previously, but instead of drawing anterior to our central sulcus, I am drawing this bulge right here posterior to that central sulcus. So this bulge right here, instead of being the precentral gyrus, we instead call this one the postcentral gyrus. Thank So let's go ahead and add those components to our brain here. So again, we are within the parietal lobe. To help us to separate between the parietal lobe and the occipital lobe, we have our parietal-occipital sulcus. And then we're going to add one more little bulge of brain matter here. And so this is our central sulcus right in the middle. And this... bulge of brain matter that we have or this bump is the most central gyrus. Okay, all right. And what we're going to see later is that some of the areas that we have for function include touch. And when we talk about touch, that's for being able to determine texture. So think about your fingertips and textures you can feel as well as different shape. Okay, here's our temporal lobe. When we say inferior lateral, that's just a fancy way to say that it's inferior and it's lateral. So if you think about where your ears are on your body and specifically on your head, they're lateral and they're more inferior compared to other components like your eyes. So they're inferior lateral. Same thing here, but we're talking about a lobe. So these, the temporal lobe is inferior lateral. The borders are going to be superior. Here's our lateral sulcus again. Posterior, we actually just have our occipital lobe and there's no real defining kind of the sulcus doesn't really come down that far to make a separation between the temporal lobe and the occipital lobe, so it's just directly behind it. And then functional areas we're going to see for our temporal lobe going forward are going to be for hearing and for smell. We have our occipital lobe. Our occipital lobe is the one that is most posterior, and our border anteriorly is that parietal occipital sulcus that we already defined. And then we're going to find that functionally, the functional area we have here is for vision. So that idea that eye is in the back of your head like mom had, that's going to help us remember that area as well. All right, the insula. Now you can't see it. X marks the spot. But like I told you, we would actually have to separate and kind of open this up right here between the frontal lobe and the temporal lobe to be able to see the insula. So it's deep inside. And we're going to find that actually the insula is important for taste. And if you think about the insula being inside, if you were to take like this arrow and point your finger inside of your mouth, inside insula A pointing into your mouth, that is associated with taste. You're pointing it inside of your mouth. We'll talk about that a little bit later. Okay, so first for the gray matter, we're going to talk about the cortical areas. So what we're talking about right now is the cortex. Now, when I talk about the cortex. Cortex is that superficial region of the cerebrum that we're talking about. Okay. What we're now going to do is layer on top of the lobes, which are structure, and the sulci, which are structure, and the gyri, which are structure. And we're going to have specific functional areas that we want to associate. Okay. So going forward, there's motor areas. Those are going to control our voluntary motor functions. You might remember that when we talked about the nervous system. Our sensory. Okay. And then we also have association areas, which is essentially where we incorporate different ideas and information and also can be associated with memory, so storage of information as well. Okay, so where we are right now is we're in the frontal lobe. So these X's show you exactly where you'd find these different functional areas. They're also again color coded to help you to determine which one is where. Now first and foremost, I want to remind you structurally that up here We are in front of the central sulcus, and it's this bulge of material right here. So this is the precentral gyrus that we find. Structurally, it's the precentral gyrus, but what it is functionally is the primary motor cortex, also known as the somatic motor cortex. So structurally, again, it's the precentral gyrus, but functionally, it's the primary motor cortex. We're also going to find up here. There is something called Broca's area. We mentioned that functionally the frontal lobe is associated with our voluntary motor. That's going to be our primary motor cortex that specifically does that. But alternatively, it's also associated with speech and our ability to control those muscles that allow us to speak. And that area here you're seeing in the blue, with the blue X is called Broca's area. Now, what I want you to notice, one of the caveats we talked about with the brain is that the left and right hemispheres are not going to be identical in terms of their function and this is one of those examples. We only find Broca's area on the left side of the frontal lobe so only on the left side. So coming back, we have in the frontal lobe, we're now going to switch colors so that we can talk about function. Okay, our precentral gyrus is going to also be known as our primary motor cortex. And again, if we say somatic, same thing as our primary motor cortex. Okay, we also have kind of in this region, I'm kind of cutting it out, but I'm just going to draw it right here. We have our Broca's area involved in controlling our ability to have speech, and that is only on the left side. Moving on to somatic sensory. Now, when we talked about somatic motor previously, that was for the motor control. Now we're talking about sensory. So for these regions first, let's look at the primary somatosensory. Where is that structurally? You might notice here against our central sulcus, structurally that is in the postcentral gyrus. Okay so that's what you're seeing there. That's involved with associated with touch. So when we talk about the primary somatosensory cortex, we're talking about function. Okay if we talk about the structure, that would be our postcentral gyrus. And then what we're also seeing here kind of two in one, we're talking about the sensory areas. We also have our visual, our primary visual cortex. And notice, please, this is in the occipital lobe. So again, eyes in the back of your head. One right here. So we have our postcentral gyrus. Our postcentral gyrus is our structure. And then we have our primary. somatosensory cortex, which is the function. Within our occipital lobe, our occipital lobe is the primary visual cortex and there's no specific defined region, it's just the occipital lobe is associated with the primary visual cortex. All right, so first look up at this little image. What you're seeing right there is essentially what looks like almost panes of glass that are going to be running within specific structures. Now, if you remember, we had our central sulcus. And what that central sulcus does is it actually acts as a separation point between the precentral gyrus and the postcentral gyrus. Now, we also know now functionally that our precentral gyrus is associated with the primary motor cortex. And we also know that our postcentral gyrus is going to be functionally. the primary somatosensory cortex. Now one is associated with our ability to have response with voluntary motor movement and the other one is to uh is associated with touch. Okay so as far as these regions um this is kind of an interesting map but it shows you how much of the cortex, remember it's only the cortex the superficial regions, is associated with those experiences we have in different regions of our body. Notice how much of our cortex we have associated with the face. So we have a lot of information coming to us from the face that we both want to be able to respond to and we want to experience. Also notice here we have our tongue, so taste. We want to have a lot of ability to respond to eat things and to be able to taste things and that sensation. And kind of a fun one here too, I don't know if you notice, your toes and the foot are associated really closely with the genitals. A lot of people have foot fetishes. So your... Cortices are kind of closely associated with one another that experience the sensations associated with those two regions of the body, which is kind of super funny. This particular slide, you guys, is just an FYI so you have an idea of which part of each cortex is associated with what. I don't need you to know anything for this slide other than to kind of just give you an idea of what's going on. Okay, so moving on to the temporal lobe and to the insula. So, the temporal lobe first. We're going to see that there's two regions in the temporal lobe that are going to have special cortices that are important for certain functions. First in black, this is going to be our primary auditory cortex that's associated with our hearing. And then here in the dark blue, we have our primary olfactory cortex. Olfactory is our fancy word for smell. Now really quickly on your own head, I want you to think about where your ears are compared to your nose. Okay, your ears are going to be more posterior compared to your nose which is more anterior. Same thing with these. So for your hearing, the primary auditory cortex is more posterior. For smell, your primary olfactory cortex is going to be more anterior. So that kind of helps you to remember where each one is located. Finally, here we have the insula. And again, that's deep inside. That's where we're seeing that lighter color. The insula I mentioned is associated with taste. So again, if you point inside of your mouth and go, ah, insula, that's going to remind you that the insula is deep. And it's also associated with taste. Okay, so let's add that really quick to our document. So our insula. We have associated with taste, so let me get this, let me make sure primary, good, still in blue, primary, gustatory cortex. And then our temporal lobe, we have two locations, one that's more anterior and one that is more posterior. If you think about your ears, your ears are going to be more posterior, so this is going to be our primary. auditory cortex and as far as smell we have our primary olfactory cortex. All right. So we can move on then to our association areas. Again, our association areas are for processing information, interpreting, also integration. We talked about memories as well. Okay, so a couple different association areas that we have here. I know this looks a little bit confusing, but let me explain Wernicke's area that's in black. This is a larger region. Okay, so what you're seeing in black, all of the black circle and what's within that black circle is Wernicke's area. Okay, notice that it's kind of at the border. between the parietal and the temporal lobe. So it's kind of right there. If you were to track back with the lateral sulcus, just where that lateral sulcus ends, that's where you would find the Wernicke's area. And right smack in the center of Wernicke's area, that blue dot is the Gnostic area. So first Wernicke's area, that's going to be associated with our spoken and written language, the ability to comprehend it. And then our Gnostic area is essentially taking all of the sensory, visual, auditory, kind of those different regions of the cortex that we saw previously. They're kind of in the same vicinity and it's integrating all of that information. So Wernicke's area and Gnostic area are right there in that same location. So we have our Gnostic area in the center and Wernicke's area. A lot of what we know about the brain we've learned from people that have different mental disorders or kind of differences and the way that they're able to determine when a specific region of the brain was associated with a certain type of function is when that person had maybe trauma in that certain area of their brain. So there's some really great books I'll try and add it to our discussion page so you can check them out But there's some really great books about how we learned a lot of what we do know about the brain there's so much still that we don't know but what we've learned a lot of it has come from people that have had traumas or regions that were maybe malformed in development that have taught us what we know about the brain. Okay so moving on to the white matter. Okay so there is central white matter when we talk about white matter as a reminder those are going to be collections of axons of the CNS if you know to be tracts there's actually three different types of central white matter that we can talk about. The difference in them is how do these axons run? Do they run from one hemisphere to another? Do they run within the same hemisphere from anterior to posterior? Do they run from the anterior part, kind of like the flower of the part, to the stem, to the brain stem? Those are kind of the ways that the different axons can run, and depending on the way that the axons run, we have a different type of central matter, white matter, associated with each one. Okay, so first and foremost, an association track, that's what you're actually seeing here in the page. We're within the same hemisphere, so imagine that this is the right cerebral hemisphere. And we're running from anterior to posterior. So that's going to be an association tract. We also have commissural. Commissural is going to be between the two hemispheres. Now you can see the corpus callosum here, but its purpose is to run between, think about an axon connection, so it's coming out of the side here, coming towards the other side. That's going to be a connection point between the two hemispheres. So the corpus callosum that I've highlighted here is the biggest version of that. We're also going to find that there's anterior and posterior commissures. Those are smaller regions that do the same thing. Okay. And then let's see what we have. Oh, perfect. Okay. So commiseral, I was trying to tell you that that was the corpus callosum, but this is a better view of the commiseral right here. We can see it running from the left to the right side and vice versa. Those are commiseral tracks. And then finally our projection tracks are the ones shown in green. So I mentioned kind of like running down the stem, like the flower to the stem. So these are going to run anterior to posterior. Okay. So running from the cortex to the inferior portion of the brain. So finally for our gray matter we have one more deep region and that's the cerebral nuclei. And within the cerebral nuclei we can define some of these. Now these, depending on the brain model, and I know that we don't have direct access to the physical brain models now, but these are deep structures. You would have to remove the cerebrum, but you wouldn't necessarily be able to see all of these structures if you were to slice down the longitudinal fissure. So there's really great brain models that kind of remove the cerebrum. And you would want to look at underneath the cerebrum, you would be able to see these structures. Okay, so when we talk about the caudate nucleus, okay, so the caudate nucleus is what you're seeing here all in green. Okay, so all of this in green is a caudate nucleus. The caudate nucleus is how your arms and legs associate with one another while you're walking. So the next time you get up, notice how your arms swing versus how your legs swing. And so that coordinated movement between your arms and your legs, that's your caudate nucleus. Now at the very end of a caudate nucleus, you have this cute little thing, it almost looks like a tail. That is called the amygdala or the amygdaloid body. Okay, so the amygdala and the amygdaloid body are one in the same. One way to remember its function is angry Amy. So the amygdala or amygdaloid body is associated with emotions. So if you think of Amy being angry, that can help you to associate the amygdala with emotions. Okay. When we talk about the colostrum, the colostrum is going to be deep, so it would actually be deep inside. That's going to be for subconscious information. So for the colostrum, maybe when you're thinking about going down the freeway, and you need to pay attention to what's directly in front of you on the freeway, so you're specifically focused on the lanes and making sure that the person in front of you isn't braking, and on your speed limit. Those are the things that are in your conscious information. for the claustrum, it's taking the subconscious visual information that's coming on all the time. So for instance, if you're on the freeway and all of a sudden, like a building was on fire, if that was something that was alarming, now all of a sudden it would draw that into your conscious information. If you're driving down a street and a ball rolls onto the road, the claustrum would say, hey, there's something that is now something we need to focus on. You would now bring that into your conscious information. So it's keeping track of all that subconscious information, letting you know when... the information is important enough to bring into your conscious uh to bring into the conscious um and then finally we have our putamen and our putamen is right here in blue and our putamen is for posture so i don't know if you remember learning about the i love spaghetti muscles those are the muscles that are going to run anterior excuse me superior to inferior down your back and help you to maintain your posture so i like to think of putamen love spaghetti so if you remember the I love spaghetti muscles and Putamen loves spaghetti, you can remember that Putamen is associated with posture. So that brings us to our diencephalon. Again, as a reminder, we have our primary and secondary brain vesicles that give rise to our diencephalon. And we would need to do a dissection down the longitudinal fissure and open it up like we've been seeing to be able to see the diencephalon. So the diencephalon is going to include the thalamus, which is kind of smack in the center. That's what you're seeing kind of in this turquoise blue. You have the epithalamus. Here we can see a little bit better. That's being represented here in orange. And then you have the hypothalamus, which is represented in purple. So epi above, hypo below. And then at the very end, kind of tracking back behind the epithalamus, you can see the structure that I circled. That's called the pineal gland. Your pineal gland controls your circadian rhythm. Maybe you've heard that serotonin is good to help you sleep. When lights go off, your brain is triggered to say, hey, it's time to sleep. And your brain releases serotonin so you can go ahead and go to sleep. So pineal gland is associated with circadian rhythm. Sorry, epithalamus and the, I got ahead of myself, the epithalamus and the pineal gland. We have our thalamus. The thalamus has a little structure on the inside which is called right here the intermediate mass and that is going to be a connection point between the two hemispheres of the brain. You have the ability with the thalamus. I want you to notice this. It does focusing and sorting of information. It's going to focus and sort and process and help you to process the information that comes from hearing, from vision, from taste. All of that information gets focused and sorted in the thalamus with one exception. olfaction, your sense of smell. And the reason that is the case is way back when we didn't have, I guess when we were hunter-gatherers, we relied really, really heavily on our smell and our brain didn't want to take the time to process it, to focus it, to sort it. It was just going to be that first response. And so we actually don't take the time to focus and sort it in the thalamus like we do with our other senses. So that's why it's with the exception of olfaction. All right. And our hypothalamus again is in purple. What you're seeing coming off of the purple hypothalamus is this cute little structure here, and that is called the infatibulum, and that leads to this hangy-bally thing that we see down here, which is called the pituitary gland. The pituitary gland and this connection between the pituitary gland and the hypothalamus, this is the major connection point between our central nervous system and our endocrine system. So we'll talk a little bit more about this when we get to the endocrine unit at the very end. but that plays a major role in our endocrine system and controlling our endocrine system. On to the brainstem. So we have a couple different regions we want to be aware of. Let me see my pop in. There we go. Perfect. When we talk about the mesencephalon, as a reminder, the mesencephalon, here's our secondary brain vesicle and it remains the mesencephalon. We have a couple different structures. Motor tracts. Again, remind yourself what a tract is right now. I'll give you a second. Remind yourself what a tract is. Okay, so we have our motor tracts and we have our primary motor cortex leading down to our spinal cord. So these are the connection points that we have. These are our cerebral peduncles. What we're going to do in this image is we're going to take the cerebrum and then we're left with this. So you can see the diencephalon at the top right here and here, which you're seeing in blue. These are our cerebral peduncles. So those are going to be those tracks that we see. They're going to help us to connect and eventually make our way down to the spinal cord. What we also have is our superior and our inferior cliculi. Now as a reminder, here's our corpus callosum. We have done a dissection down the longitudinal fissure so we can see the inner structures. And here is our pineal gland. Here's our intermediate mass. Here's our thalamus. So what we're seeing if we go just below the thalamus, we have these two structures right here. Now, what I want to tell you is we only have one hemisphere of the brain right here, and we only see one of each. These are both actually in pairs. So when I say colliculus, colliculus is singular, colliculi is plural. And so there are superior colliculi, meaning that there's two of the green structures. There's one that's associated with each hemisphere, so that's why we only see one right now, though. And then there is inferior colliculi, meaning that there's two of these that are inferior as well. Now, for the superior colliculi. These are going to be visual reflex centers. So think about your eyes. Those are going to be more superior versus your ears. If you think about where your eyes are versus your ears, your ears are going to be more inferior. So your superior colliculi, like your eyes being superior, those are associated with your visual reflex centers. Your inferior colliculi, like your ears being more inferior to your eyes, those are in charge of your auditory reflex centers. Collectively, what we call them together is the tectal plate. So if we just pointed at one single region, superior colliculi, inferior colliculi, and then collectively together, tectal plate. This is another view. So remember, we've taken off the cerebrum. And so what you can see there, you can see highlighted back and forth, just so you can see. Our superior colliculi are going to be superior. Our inferior colliculi are inferior. So eyes, ears. All right, we're moving down. And so what we just covered, here is our tectal plate. And so moving down here, we're into the pons. Okay, so here's our pons. This is going to be bulging out. And like it mentions right there, it's the anterior side. So this is the anterior side if you were kind of confused at where you are. We see that bulge facing anteriorly. Now, these are tracts. So these are going to be collections of axons. And what we're going to find is that there's some really, really important control centers here. Here we have our autonomic respiratory centers. Now remember that when we talked about autonomic in association with the nervous system, autonomic is essentially automatic. Okay, you don't remind yourself to breathe, you just breathe. Now there's a couple different things that we control with the pons in terms of our respiration. The rate is one thing that we control and the depth of the breathing. Now the pons and the medulla, these actually go hand in hand to be incredibly important as controlling the respiration. So we're going to actually find that the pons, when we say controls the medulla's effect on breeding, we're going to find the medulla is also incredibly important for breeding as well. All right, moving down to the medulla, also known as the medulla oblongata. So it's this region we have right here just inferior to the pons. And we're going to find that there are two pyramids. These pyramids are motor tracks. So as a reminder, tract, a bundle of axons in the CNS. What we find is that there's crisscross. So actually like the X, this decussation of pyramids means that they actually crisscross one another at this location. So that's what the decussation means is they crisscross these two motor tracks. That's what you're seeing. That's from my previous slide. This is a crisscrossing interesting right here. So these are going to be those pyramids still on the medulla oblongata. It actually is considered absolutely essential for life because we control a lot of different things. Let me actually just start you down here at the third bullet point, the respiratory center. This is going to work hand in hand with which structure that we just talked about. Do you remember? Okay, let's take a step back and remind you. Remember autonomic respiratory center that we find in our pons? Yeah, so our respiratory center of our medulla oblongata is going to be working in tandem in order to be able to control the respiratory rate. So both of these structures work hand in hand with one another and then they're close in proximity to one another so that makes sense. But in addition to your breathing, cardiac center is going to help to control your heart rate and the strength of the contraction. So how much blood are you going to be pumping out? Also vasomotor, when you see vaso think vessel. So vasomotor center actually helps to control our arterial diameter which helps to control our blood pressure. We'll learn a little bit more about that when we get to blood. So as you can see heart, blood pressure, respiratory rate, the medulla oblongata is a key key structure in making sure that we stay alive. On to the cerebellum. The cerebellum essentially is baby cerebrum or little cerebrum. And so in purple you can see the structure that we're focusing on. Just like the cerebrum, it actually has two separate hemispheres, a left and right side. Instead of saying cerebral hemisphere, we say cerebellar hemisphere because it's part of the cerebellum. The midline in between, we don't have a longitudinal fissure. We have this little bulge. It's called the vermis. And the midline is actually important in and of itself. We're going to find that overall the cerebellum is important for things like your muscle memory. So if you, when I tell you to maybe rewrite your answers for the exam or on your lecture objectives list over and over and over again, I'm helping to build muscle memory. We're actually going to use our cerebellum to have that muscle memory and to kind of call in on it. Also proprioception. Proprioception is your understanding of yourself in space. So your awareness of yourself in space and how you exist in a space. So that's essentially what that is. What is going to help us to separate? So if you look right here where I'm drawing the line. The separation point between the cerebrum and the cerebellum, that's called the transverse fissure. Okay, so this little separation point is called transverse fissure. If we look inside, so I'm going to cut, make a dissection right down the vermis, and I'm going to look inside one of the hemispheres. Now I can see, notice that there's gray matter on the outside just like there is in the cerebrum. and there's actually white matter on the inside just like we see with our cerebrum. So the outer gray matter that is essentially our cortex so that's the superficial area that bumpiness that you're seeing on the outside of the cerebellum that's called the folia so those are folia that you're seeing all those little bumps. The white matter that you see on the inside is called arborvitae so the white matter all of this white matter is called the arborvitae. And then finally, just like we had, and you can't really see it very well, so I'm not going to point it out on this slide, but just like we had the cerebral nuclei that were deep within the cerebrum, we actually also have deep cerebellar nuclei. So these are going to be nuclei, collections of soma, but instead they're in the cerebellum, so they're called cerebellar nuclei. For this part here, we have, what we're going to focus on is our ways that we support the brain and protect it. And so when we talk about this, we're going to talk about various layers of connective tissue that are going to help to support the brain and protect it in that way. When you think about it, think about the cranial cavity and all these cranial bones that are making up the cranial cavity. That's really hard structure and so we need to have some kind of separation protection. So not only do we have connective tissue and we're going to identify these different layers, but we're also going to find that there's fluid that's going to surround the brain. So it's almost like the brain's floating in like on a waterbed or something like that. So it gives it the ability to be a little bit more protected. Now, when we say cranial meninges, these are the layers of connective tissue that I'm going to talk about. Meninges is plural. Meninges is singular. OK, so if you see menings on your lecture objectives list, that's singular. Meninges is plural. And again, it's going to provide us all of this protection and these layers. Now, the three layers that we're going to see are the dura mater, the arachnoid mater, and the pia mater. The arachnoid mater, we're going to see actually there is kind of some cobweb-y looking stuff. It's kind of how the connective tissue looks. And so that's going to be the arachnoid mater. And then we have our dura mater and our pia mater. So notice on this skull, we're actually seeing a cross-section. Where we are right here is we're going to be... in this location first that I want to draw your attention to. So this location that we're in right here is where our two parietal bones would meet. So we're at the very top. What we're seeing here is our cortex. And in between this space right here, you're seeing between these two sides, the left and right side, this invagination is actually going to be our longitudinal fissure. So the longitudinal fissure is the invagination of the brain we're seeing. Now what I want you to notice is when we talk about these different layers, these different layers are layers of connective tissues that are layered right on top. We're going to start from the most superficial and then make our way more deep. Now the dura mater, let me change my colors as I go, the dura mater actually has two sub-layers. There is one layer that is called the periosteal layer, and there's another layer that's called the meningeal layer. Now let's think about this. So let me just highlight for you where the first layer is. Here's our first layer right here. That first layer that I just highlighted, that is our periosteal layer. Now what comes to mind when we say periosteal? Any idea? Hopefully periosteum and hopefully bone. So the periosteal layer is the layer that is closest to your bone. The meningeal layer Let me show you this. Now it's a little bit different. Watch. I'm going to come along the bone, that periosteal layer, but then I'm going to dive down. See it? Diving down that longitudinal fissure. Then I'm going to dive and then come back up. So the difference between our meningeal layer and our periosteal layer is how they run. The periosteal layer is more superficial and it's just going to run right along the bone. It's not going to dive in with each crevice, each nook and cranny of the brain. However, the meningeal layer, let me just add that here, our meningeal layer, It is called the meningeal layer because it's closest to the other meninges, so that's why it gets its name. It's actually going to dive down. Now, it doesn't follow every nook and cranny of the brain, but it does follow with the major fissures. So you do see that diving down as you see here. Now, what is between the two layers? I want you to notice right here in the blue, that region right there is called the dural sinuses. Now, when we say dural sinuses, we are specifically talking about blood vessels, and we're talking about blood vessels within the brain. And so in between this blue... space that we're going to see here, we're going to find that that is where we're going to find our dural sinuses. So I'm going to draw, not right inside of one, but kind of in between. I'm going to draw just kind of like a little rectangle right here. That's not good. There we go. And that guy is our dural sinus. Now there's many dural sinuses, so we're just getting an example of one that would be there. What we're going to see in the brain, the reason why I say in the brain specifically is because when we get to the spinal cord, we're going to find that there's slight differences in these spaces. Okay, so at least for the brain, we're going to find that there is potential epidural space and there is subdural space. Now let me explain that. If I say epidural, epi means above the sinuses. Okay, so epidural means above the sinuses. There is only potential epidural space. There is no actual space there, but there's potential for there to be space. Why would we need space in the brain that we don't have right now? Well, if you were to start to have bleeding of the brain, swelling of the brain, your brain isn't draining the way that it's supposed to. That means then we do have a little bit of space that can be filled, and that would be the epidural space that we would move into. So that's why it's potential epidural space, but as it exists normally. you don't have that epidural space open. We do however have subdural space. So we will have space below and and that's going to be with things like cerebral spinal fluid. So we'll talk a little bit more about that in a second. Next up we have our arachnoid mater. Our arachnoid mater is going to be, let me do a different color, our arachnoid mater is going to be all of this that we see with kind of that cobwebby stuff. Okay so this is all our arachnoid mater. It is deep to our dura mater and specifically deep to the meningeal layer of the dura mater. And what we're going to find is within this cobwebby space, all of this, we're going to have CSF, cerebral spinal fluid. So if we have our cerebral spinal fluid, well, that's perfect that it's in that location because it's going to help to cushion the brain and prevent it from running into our bone. But also what I want you to notice is these little projections that are coming into the area where the dural sinuses are. These little projections that we see of the arachnoid mater are called arachnoid villi. Villi is plural. Villus is singular. These little projections are going to be our points at which we can have flow from the cerebral spinal fluid to the sterile sinuses. This is how we connect back to our vessels so that we can keep the flow of cerebral spinal fluid flowing through the brain or around the brain. So that's the arachnoid villus. This is a special structure that is part of the arachnoid mater. And then finally, we have our pia mater. Our pia mater is going to be the deepest meningeal layer. And we're going to find that this is this tiny little layer you see me highlighting right around the brain. It follows every single nook and cranny, every sulcus, every gyrus. So this is going to be our pia mater. And the pia mater is made of areolar connective tissue. And that areolar connective tissue, you might remember, it provides strength and it also provides binding. And so it binds right down, almost like shrink wrap, right over the top of the brain. So one of the things I mentioned was the dural sinuses. When we talked about, talk about septa, if you think about a septum, for instance you have your nasal septum, that is a separation point between, for instance, your nose and the two nasal passages. The septa, or these divisions, are going to be separation points, and then we have our sinuses which are going to be specific vessels that we see in certain regions. So first let me just show you this table right here. This is what I want you to know for lecture. So you have a septum. Where that septum is located is going to be the second part of the table. And then the sinuses, the vessels that run within that region, is listed next. So let me just show you one example first. Our longitudinal fissure, I've been showing that a lot to you. That is going to be directly between the two cerebral hemispheres. What the septum is called is the Fulx cerebri. And the sinuses that we see there are the superior and inferior sagittal sinuses. So let me go ahead and show that to you. This area right here is the fulx rebri. You're only seeing half of the brain or kind of where it would be. Here you would only have the right hemisphere still intact. So here is the septum. We're right here within the longitudinal fissure. And let me just show you here, highlight in the blue. Right here in blue, hopefully you can see it, you have a superior sagittal sinus. And then right here in blue you have the inferior sagittal sinus. So those are the two sinuses. So see with this location again we're in the longitudinal fissure and that's the Fulx Cerebrae. Here is another example. This is actually with the brain. You wouldn't be able to see the inferior sagittal sinus because it would be deep inside, but you can at least see the superior sagittal sinus. And again that's running within the Fulx Cerebrae. Tentorium Cerebelli. Hopefully you hear in that cerebellum. Where is this going to be? At the transverse fissure. As a reminder our transverse fissure is that separation point, it's that invagination that's going to be between the cerebrum and the cerebellum. And what we see there is there's a straight sinus and a transverse sinus. Now the transverse sinus, hopefully you can see it right here, runs transversely. So this is our transverse sinus. And again, what we call that septum is the tentorium cerebelli. And I think... perfect, okay. Our transverse here is running around, kind of around the edges. Our straight sinus is medial, so I want you to notice it's kind of like it's almost somebody's poking you directly in the back of the head. This will be our straight sinus right here. Our Foulk's cerebelli, that's going to be essentially near the vermis. It's between the two hemispheres of the cerebellum, and there we have our occipital sinus. I have the Foulk's cerebelli right here, so you can at least see where that location is. Yeah, perfect. Okay, so here's our Foulk. Fulcera Belli, and there's the occipital sinus right there. Okay, so you can see the occipital sinus right there. And then finally we have our diaphragm of cilia. Do you remember learning about the celloturcica? Here's where it comes back. So what actually sits in the celloturcica, it's not you riding a butterfly into the sunset, but instead what sits there is actually the pituitary gland that we just learned about. So right within that septum, the diaphragm of cilia, we find the cavernous sinus. Think about it being like in a little cave. So here's our diaphragma cilia. Here's our pituitary gland, diaphragma cilia. And I believe it's this vessel right here. So that would be our cavernous sinus. Okay, so just make sure that you're able to associate each of the different septa with the sinuses that would be in that location. And that's what I need you to know for lecture. So as far as the brain ventricles go, this is not what I was talking about with the primary and secondary ventricles. This is those are vesicles. This is entirely different. These are ventricles. So when we talk about these regions, what we're going to have is essentially cerebral spinal fluid. That's going to be able to circulate in and around the brain. And we're going to find that there is actually a connection point where we are going to empty back into venous flow into our dural sinuses so that we can continue to have that flow go through. So think almost like a, I'm thinking of like a fountain pump that keeps the water flowing through a fountain. We have this continuous flow between the circulatory system and the cerebral spinal fluid. These are the brain ventricles. And so the brain ventricles you're seeing in blue, they're weirdly named and weirdly numbered. So let me just explain and walk through. Okay, so if you have your lateral ventricles, there's one on the left and right side, and that's why they're called your lateral ventricles. And then this is them from the lateral view. So there's your lateral ventricles here, which I want you to see is then you're going to go into your next one. Now, I guess maybe because the lateral ventricles were considered first and second. But anyways, we go from the lateral ventricles, and the next place we go is to our third ventricle. Okay, so third ventricle is next. From there we're going to go into a structure called the cerebral aqueduct, and that's kind of like our little connection point between the third ventricle and the next one. So this is our cerebral aqueduct, and the next one that we have is our fourth ventricle. Okay, so it goes lateral ventricles, third ventricle, cerebral aqueduct, and then fourth ventricle. So I want you to notice the locations of these. The lateral ventricles are located within the cerebral hemispheres. Where we find the third ventricle is right in the location of where we have the diencephalon. Our cerebral aqueduct is going to help us to connect to the brain stem, and then we're going to see that the fourth ventricle is within the brain stem and the cerebellar region. All right, so for our final slide, we are going to go over the flow of the cerebral spinal fluid. You're welcome to walk through it on your own afterwards if you would like. Basically, wherever you see these squiggly lines, We are going to have what's called choroid plexus. Choroid plexus, you might remember, is associated with the ependymal cells. And the ependymal cells, their function as glial cells are to help to make CSF or cerebrospinal fluid. So what we're essentially having is as we make our way through this process of kind of working our way down the ventricles, we're going to get infusions of fresh CSF as we go. We're going to start in the lateral ventricle and we're going to get an infusion of CSF there. with the choroid plexus. That CSF is then going to flow down to the third ventricle and we're going to get a fresh batch of CSF in the third ventricle. We'll then make our way down the cerebral aqueduct to the fourth ventricle where, you guessed it, our choroid plexus is going to give us a fresh batch of CSF. And then we're going to be able to make our way out. Here it shows you kind of to the lateral apertures and the median apertures. This is where we're going to actually make our way finally into the subarachnoid space. The subarachnoid space is going to be associated with our arachnoid water and that is where we have the CSF that's going to flow around the brain. So all these arrows in black that you're seeing after that is flowing CSF around the brain. Finally you might remember the arachnoid villi so let me just draw your attention up here to eight. That's the arachnoid villi where we have the connection points with our dural sinuses. These are actually veins that we're going to dump the CSF into after we have had it flow around the brain. So essentially with creating new CSF we provide fresh nutrients, we provide fresh fluid to go around the brain. Then as that fluid goes around the brain, it's going to start to collect more and more of the waste products of the brain. And so we can dump that back into the vena circulation when we're done with it, continue to get fresh. So that's essentially how we have this take place. All right, that is our lecture for the brain.

So make sure you check that out first. Another thing is that as we go through, we're going to learn a couple new definitions. You might remember that I've kind of been making a big deal about what a nerve is and the definition of a nerve. We talked about collection of soma in the PNS.

So we're going to actually see that there are alternative definitions for these same kinds of structures but in the CNS. So we're going to see a new name for a bundle of axons in the CNS specifically and we're going to see a new term or name for a bundle of soma in the CNS. Another thing to note is that as we go through the brain lecture you're going to find that there's going to be redundancy in terms of where we're looking at on the brain for structure and function.

So as we've been going throughout the course, you may note that I've been identifying structure and function independently of one another, so you have an understanding of both. Now, the cerebrum is what we think about most when we draw the brain. And so that's what I'm drawing here.

Not the best version, but it will do. And what I'm going to be drawing for this brain and again on this brain, specifically the cerebrum, is two things, the structure and the function. To help us keep track, I'll go ahead and draw the structure and all of the structural components in black.

And then for the function, I'll go ahead and write all of those in blue. First and foremost, the brain is about three pounds. And if you imagine taking that open cranial cavity, imagine removing the brain, taking that cranial cavity and pouring in a liter of soda, which I know sounds super weird, but that's about the volume that you have within your cranial cavity to contain the brain.

So the brain itself is about the volume of a liter of soda. Now when we talk about the brain being able to receive and process information, let's associate that back with our understanding of the nervous system. When we have information that we're receiving, we're receiving that information from the PNS, or our peripheral nervous system. When that information comes from the peripheral nervous system and is received by the CNS, our central nervous system, that as a reminder is going to be our sensory division of the nervous system. Alternatively, when the brain processes and then sends out responses, that sending out of the responses is associated with the motor division of the nervous system.

So we're going to receive information to the central nervous system, that's our sensory, and then we're going to process, decide how we want to respond with our brain, send that information back out and how we want to respond, and that's going to be our motor division. Now as far as the visual organization of the brain, you're going to notice in the slides coming up that I have done a lot of color coding to help you to keep track of what's what. First and foremost here you're seeing that in green we have the cerebrum.

The cerebrum is what I just started to draw on the word document so we can keep track. This is what we normally associate with the majority of our brain, so it's the largest region. And so with that we have our frontal lobe, temporal lobe, parietal lobe, occipital lobe, and also one that you can't see right here because it's deep is called the insula. We're going to see that a little bit later.

You also have the diencephalon. The diencephalon is going to be made up of a couple different thalmi. Now when I say thalmi, that is plural for thalamus. Our thalamus is one structure, and you can't really see where it's pointing, but it's right here in the middle, okay?

And then on top and below, we have hypo below, and let's see, do I see a label for it? I don't see it, and that's okay. We have an epithalamus, epi above the thalamus as well. So we have our epithalamus, the thalamus, and then we have our hypothalamus. So those are all components of the diencephalon.

For our brain stem, I like to think of the brain stem and stem as the stem of a flower. So this would be the actual stem component where maybe the cerebrum would be the flower component of the flower. But in purple you can see the mesencephalon.

It's hard to see where this is pointing, but our mesencephalon is pointing to right here. Our pons is right here, and then we have our medulla oblongata, and those are all part of the brain stem. We finally have the final major region of the brain which is the cerebellum.

If the cerebrum is the largest component, think of cerebellum like a baby brain or a mini brain. So the cerebellum is right here. Now this view that we're looking at is a lateral view, but more specifically in order for us to see these inner structures like the diencephalon, the inside of the cerebellum as we're seeing it here, we're actually only looking at one hemisphere of the brain. Now when I say hemisphere, we have two hemispheres. We have a left and right.

And so we would be able to do a dissection right down the middle of those two hemispheres. If we looked inside, this is what we would see. Where would I have to dissect?

Where would I be looking? Well, we're going to find that there's a special fissure, which is an invagination called the longitudinal fissure. And that fissure is kind of the marking point between the two hemispheres of the brain.

So we're going to see that structure later. If we did our dissection right down that line, that's how we'd be able to see all of these inner structures. Keep that in the back of your mind.

All right, this particular slide and the slide that follows, you're seeing here, these two slides are associated with a level three objective. Now what you want to be able to do is take a brain region, and these are the regions that we just talked about, and associate that brain region with the primary brain vesicles. The primary brain vesicles are all right here. And also with the secondary brain vesicle.

Those are all of the ones right here. I am going to do a separate mini video to help you to decipher this because sometimes it's a little confusing for students and I'll color code it. but it takes a little bit of time to walk through that so I'm going to do that in a separate little mini video that I'm going to record after this one. Okay, as far as the regions, the primary brain vesicles and the secondary brain vesicles associated with the brain regions, this slide right here walks you through specifically the secondary vesicles.

So what you're going to see listed first is for instance the telencephalon. That is going to be the secondary vesicle for the cerebrum. So let me just walk you back here really quick so you can see. Here's our telencephalon, which is our secondary brain vesicle and that's for the cerebrum. Now when I say brain vesicles and primary and secondary brain vesicles, these are associated with embryonic development.

So our mature regions of the brain are the ones that we've already covered, the cerebrum, diencephalon, brain stem, cerebellum. But these are the structures that are going to develop through our embryonic development to help us to make these mature regions. So again I'll do a recording for these two slides coming up in a little bit. All right so first up is cerebrum, one of our first main regions. What I want you to notice at the top of the slides as well to help you to follow along, I've actually incorporated the primary and secondary brain vesicles to help you with this level three objective.

So just note that if you see these arrows at the top of a major region, that's to remind you of the primary and secondary brain vesicles that lead to this mature region. So coming back to the cerebrum, what are we going to have here? Well, conscious thought, so our ability to actually have the idea of conscious thought and our ability to have function. Now when we talk about this, we're going to find that there's special functional regions that allow for these certain things. For instance, voluntary motor.

You might remember me talking about this when we talked about the divisions of the nervous system. So it's our ability to control skeletal muscle. Also visual.

We're going to find that there's regions within the cerebrum that allow for our ability to see or to process vision. And auditory. The same thing, but with hearing.

Now when we talk about these areas, what I want you to notice here is We're instead of looking at a lateral view, last time we were actually looking from the side, so I'm just drawing an arrow, and if we had dissected right down the middle like this, we dissected right down the middle like this and removed one of those hemispheres, we were looking at the inside, so we were looking at it from this side. So that was a lateral view that we're looking at. However now, let me see if I can get rid of these, now it's as if we took a coronal plane and we sliced right down the middle. And so now what we can see is if we're looking, imagine that maybe the person's eyeballs would be in the front here. There you go.

This would be the kind of view that we're looking at. Okay, so maybe an anterior view and from a coronal section. Now there's a couple different things I want you to notice.

Here's our gray matter and here's our white matter. Okay, so when it comes to the gray matter, I want you to notice that that's all along the most superficial part of the cerebral. Okay, so all of this is gray matter. As a reminder, our gray matter is a collection of soma. And specifically here, we're looking at within the CNS.

Now, when I talk about a collection of gray matter or collection of soma within the CNS, here comes our definition. Do you guys see this cerebral nuclei? Nuclei is plural for nucleus. And a nucleus is how we define or our term for defining a collection of soma in the CNS. So let me go ahead and erase this guy really quick.

So a nucleus is a collection of soma in b c n s okay alternative to that in the peripheral nervous system was a ganglion So if we're talking about it in a collection of soma in the PNS, we say ganglion. If we're talking about a collection of soma in the CNS, we call it a nucleus. And if we say cerebral nuclei, that is plural.

That means there's multiple regions of these. The other definition I want to make you aware of now is a tract. A tract is essentially the CNS version of a nerve.

So if you might remember, a nerve is a collection of axons in the PNS. Same thing here but in the CNS. So a tract is a of the axon in the CNS.

So make sure you can compare and contrast those definitions. All right, so coming back to our little drawing here, just drawing your attention to the outside. So where we see that it's darker in the gray matter, that area is actually called the cerebral cortex.

Okay, so everywhere that you're seeing this dark region here, that is the cerebral cortex. It's just this superficial area. Okay, so the cerebral cortex is a superficial gray matter.

We then have the white matter, and so that's all of this lighter colored part right here. Okay, so all the white matter, with the exception of these dark regions that you're seeing. These darker regions right here are also going to be... collections of soma. And so we actually call those, the deepest there, those are the cerebral nuclei.

So those little dots that I made are on the cerebral nuclei. Ventricles are entirely separate. We have fluid flow to provide fresh nutrients to remove waste from the brain. And that fluid region, think of it almost like a little river running through the brain, that's the ventricle. So that's an entirely different structure that we'll talk about later.

All right. Finally, for this slide, something I want to introduce. is gyri, sulci, and fissures.

Now gyri is plural for gyrus, so if we talk about just one, singular is gyrus. Sulci is plural for sulcus, so you'll often hear me talking about the sulcus, and fissure is just the original version for that, so that one's nice and easy. Now each of these is slightly different. Sometimes you'll see sulcus and fissure used interchangeably specifically for certain structures. So I just want to draw your attention to that now.

If you see me use sulcus or fissure for something and in maybe online or in your book, you see sulcus or fissure used alternatively. It's just that they're both used interchangeably for certain structures. So don't let that get you don't get too hung up on that. But let's go ahead and define these first.

So when we talk about a gyrus. is a bump of matter. So this will actually be something that actually protrudes or something that you could feel as kind of a bumpy region.

So for instance, if I was talking about a big bumpy region, it wouldn't be quite this one. But this would be an example of kind of a bump that I'm talking about when I talk about a gyrus. We're going to see that there is going to be a big gyrus that we're going to associate with, with sensory.

and there's going to be a big gyrus that we associate with motor. So we're going to talk about that next. When it comes to a sulcus, a sulcus is a small invagination.

kind of coming off the page here so let me write it over here and I'm going to eventually erase this leader so we have the room but invagination okay or a groove so we're going to see that there's different sulci that are going to be present and that's going to be smaller than our next structure which is going to be our fissure a fissure is a deep invagination So earlier I told you about our longitudinal fissure, which would separate the two hemispheres of the brain. That longitudinal fissure is a really, really deep invagination and so deep that it's almost like somebody took a knife and kind of went through that area. So it's nice and deep. Okay, so a gyrus is a bump, a sulcus is a small groove or invagination, and a fissure is a deep groove invagination.

So from this view, just a couple things you can see. Right here, if you see where I'm pointing, that's actually going to be the longitudinal fissure. So let's do it in color. So right here, this is our longitudinal fissure. And we're also going to see that there are different structures such as the lateral sulcus right here.

And here's another lateral sulcus, so we'll be able to see those a little bit later as well. All right, so first focusing on the gray matter. The gray matter itself, like I mentioned before, there's two areas where we're going to have a collection of soma.

Now I told you that's what's going to be most abundant, which is going to provide for the color that we're going to see, but it's not the only thing that we would see. So let me just show you right here for gray matter. That includes our cerebral cortex, which is the superficial region right here, and our deep cerebral nuclei, which are those that are redox-rich right here.

So as I mentioned, collections of soma. So we have our motor or interneuron soma. Okay.

And we also are going to have dendrites, teledendria, and myelinated axons. Now again, what's going to be most abundant is the soma to give its color, but we do have some other structures there too. Our white matter, which is kind of sandwiched in between the deep cerebral nuclei and the cerebral cortex.

That is going to be a collection of axons in the CNS. And so that's what you're seeing here is mostly myelinated axons in the white matter. Alright, so we are looking at the cerebrum.

So if we look at the cerebrum, there are two cerebral hemispheres. Okay, so we have our left cerebral hemisphere and we have our right cerebral hemisphere. Notice that they pretty much look the same, at least how they're depicted, and if you looked at a brain and you did a dissection, they would look pretty similar as well. Here is the structure that I keep trying to mention. This is our longitudinal fissure.

Okay, so it's that deep invagination that you're seeing right in between the two hemispheres. The connections between the two hemispheres are called tracts. Let's remind ourselves, tracts are defined as a collection of what?

Can you remember? They are a collection of axons in the CNS. Okay, so that's going to help us to make connections between the two hemispheres. We also have one really large tract that we're going to see and that's called the corpus closum and I'll draw your attention to that later. That is our largest tract and we're going to see that it's really white and really prominent, kind of right deep.

and central to the cerebrum. Okay, so let me erase this. This is just a lateral view, again, what we saw before.

Here's that corpus callosum. We were just talking about all of this that you're seeing right here. That's our corpus callosum, okay? And so as a reminder, that is a tract, and that is going to help us to have connection points between the neurons in one hemisphere versus another. All right, there are some caveats to the brain.

One of the caveats being that even though they look similar to one another and anatomically might look identical, they are not functionally identical, meaning that we're going to have some functional regions that exist on the left hemisphere and not on the right. And I'm going to help you to decipher those as we go through. There are some regions that overlap in their function, meaning that we can have two regions, maybe one in the left and one in the right, and they both do the same thing. So there's also functional overlap as well.

And then what you've probably heard before, which is super weird, that our right cerebral hemisphere controls the left side of our body and the left cerebral hemisphere controls the right side of our body. So try not to think too much about that as we're going through it, but it's kind of amazing you can think about the brain using the brain and respond. So these are the caveats associated with the brain. All right, let's first focus on the cerebrum.

And so when we talk about the lobes of the cerebrum, With the exception of the insula, like I've mentioned before, these should be comfortable for you based on the cranial bones that you studied for the previous lab components. So all of these are going to be anatomically distinct lobes of the brain that are going to be deep to the cranial bones that you associated with them previously, except for what's called the insula. So let me just take a step back here and start to define these.

So we have our structure first okay so when we're looking at these different regions our frontal lobe here okay our temporal lobe is right here our parietal lobe is here We have, do you guys remember what's back here? Eyes in the back of your head. Occipital lobe.

That will actually become important when we talk about the function of the occipital lobe. And then the final one, the insula, is actually in here. So if we were to actually kind of separate the frontal lobe from the temporal lobe and peek inside, that's where we would find the insula.

Okay. So that's the insula right there. And that's going to be our final lobe.

So. frontal lobe is what's being represented here in blue so you can see the frontal lobe this is our anterior lobe which makes sense if you think about where your frontal bone is and what we're going to find is some different structures that are going to help us to define where the frontal lobe is located first and foremost we're going to have what's called our lateral sulcus i started to draw this on the other image but this line right here this dark line that is our lateral sulcus We also have our posterior border for the frontal lobe and that is our central sulcus. If you look at this dark line right here, that is our central sulcus. I wish I could avoid those lines, I'm sorry you guys. Okay, now when we say that we have the feature the precentral gyrus, I'm going to show this to you on my other drawing as well, but here let me just show you again is the central sulcus.

As a reminder, a sulcus is a tiny invagination. A gyrus is a prominent bump. It's a bulge on the brain. So I'm going to draw where that would be.

Okay, all of this region here that I'm drawing with, that is where the precentral gyrus would be. Pre means before, and it's before the central sulcus. So it's called a precentral gyrus because it's a bump. or bulge of the brain that's before the central sulcus. Okay, so that's the region that we're talking about right there.

We're also going to find going forward that we have different functional areas. So we're going to come back to the functional areas later. We're going to find that there is our voluntary motor, which will be associated with our precentral gyrus. So we'll come back to that. And as well as our ability to control the muscles for speech.

We're also going to find that those functional regions are in the frontal lobe as well. And so here what we're seeing This structure right here is actually going to be our lateral sulcus. That's what I would open up and try and kind of dissect out or that location I try and dissect out if I was trying to get to the insula. And then right here over the parietal lobe, so I'm going to move the parietal lobe out of the way just so we can move it back a little bit, we would have this structure right here.

This is an invagination. We call this invagination the central sulcus. And that central sulcus has a bulge in front of it.

And that is called the precentral gyrus. Let me just add back our parietal lobe back here so we don't confuse it. All right. Next up is our parietal lobe. These black...

it's like x marks the spot so when you see the x is just showing where the lobe is the parietal lobe here is shown in yellow our borders anteriorly is again our central sulcus which we already defined what we're finding is that the lateral sulcus doesn't run all the way through to find that border and that's why you're seeing these little dots so it doesn't go all the way through but it's part of the border it's a lateral sulcus if you were to track the lateral sulcus on a brain model with your finger and just continue to work your way back you'd be able to define the rest of the border The other border that we're going to see is one that we haven't defined yet, which is called the parietooccipital sulcus. Again, as a reminder, a sulcus is a small indagination. When we say parietooccipital, that is going to be a sulcus between the parietal lobe and the occipital lobe. So think about where you might find that. Do you remember where the occipital lobe is?

It's right here. Okay. And so right here where my little cursor is, this would be my parietooccipital sulcus.

Okay, what we're going to find within the parietal lobe is another bulge of brain matter. Okay, so I want you to notice I'm drawing like I did previously, but instead of drawing anterior to our central sulcus, I am drawing this bulge right here posterior to that central sulcus. So this bulge right here, instead of being the precentral gyrus, we instead call this one the postcentral gyrus.

Thank So let's go ahead and add those components to our brain here. So again, we are within the parietal lobe. To help us to separate between the parietal lobe and the occipital lobe, we have our parietal-occipital sulcus.

And then we're going to add one more little bulge of brain matter here. And so this is our central sulcus right in the middle. And this...

bulge of brain matter that we have or this bump is the most central gyrus. Okay, all right. And what we're going to see later is that some of the areas that we have for function include touch. And when we talk about touch, that's for being able to determine texture.

So think about your fingertips and textures you can feel as well as different shape. Okay, here's our temporal lobe. When we say inferior lateral, that's just a fancy way to say that it's inferior and it's lateral.

So if you think about where your ears are on your body and specifically on your head, they're lateral and they're more inferior compared to other components like your eyes. So they're inferior lateral. Same thing here, but we're talking about a lobe.

So these, the temporal lobe is inferior lateral. The borders are going to be superior. Here's our lateral sulcus again. Posterior, we actually just have our occipital lobe and there's no real defining kind of the sulcus doesn't really come down that far to make a separation between the temporal lobe and the occipital lobe, so it's just directly behind it. And then functional areas we're going to see for our temporal lobe going forward are going to be for hearing and for smell.

We have our occipital lobe. Our occipital lobe is the one that is most posterior, and our border anteriorly is that parietal occipital sulcus that we already defined. And then we're going to find that functionally, the functional area we have here is for vision.

So that idea that eye is in the back of your head like mom had, that's going to help us remember that area as well. All right, the insula. Now you can't see it.

X marks the spot. But like I told you, we would actually have to separate and kind of open this up right here between the frontal lobe and the temporal lobe to be able to see the insula. So it's deep inside. And we're going to find that actually the insula is important for taste. And if you think about the insula being inside, if you were to take like this arrow and point your finger inside of your mouth, inside insula A pointing into your mouth, that is associated with taste.

You're pointing it inside of your mouth. We'll talk about that a little bit later. Okay, so first for the gray matter, we're going to talk about the cortical areas.

So what we're talking about right now is the cortex. Now, when I talk about the cortex. Cortex is that superficial region of the cerebrum that we're talking about.

Okay. What we're now going to do is layer on top of the lobes, which are structure, and the sulci, which are structure, and the gyri, which are structure. And we're going to have specific functional areas that we want to associate. Okay.

So going forward, there's motor areas. Those are going to control our voluntary motor functions. You might remember that when we talked about the nervous system. Our sensory. Okay.

And then we also have association areas, which is essentially where we incorporate different ideas and information and also can be associated with memory, so storage of information as well. Okay, so where we are right now is we're in the frontal lobe. So these X's show you exactly where you'd find these different functional areas. They're also again color coded to help you to determine which one is where.

Now first and foremost, I want to remind you structurally that up here We are in front of the central sulcus, and it's this bulge of material right here. So this is the precentral gyrus that we find. Structurally, it's the precentral gyrus, but what it is functionally is the primary motor cortex, also known as the somatic motor cortex. So structurally, again, it's the precentral gyrus, but functionally, it's the primary motor cortex.

We're also going to find up here. There is something called Broca's area. We mentioned that functionally the frontal lobe is associated with our voluntary motor. That's going to be our primary motor cortex that specifically does that. But alternatively, it's also associated with speech and our ability to control those muscles that allow us to speak.

And that area here you're seeing in the blue, with the blue X is called Broca's area. Now, what I want you to notice, one of the caveats we talked about with the brain is that the left and right hemispheres are not going to be identical in terms of their function and this is one of those examples. We only find Broca's area on the left side of the frontal lobe so only on the left side. So coming back, we have in the frontal lobe, we're now going to switch colors so that we can talk about function. Okay, our precentral gyrus is going to also be known as our primary motor cortex.

And again, if we say somatic, same thing as our primary motor cortex. Okay, we also have kind of in this region, I'm kind of cutting it out, but I'm just going to draw it right here. We have our Broca's area involved in controlling our ability to have speech, and that is only on the left side. Moving on to somatic sensory.

Now, when we talked about somatic motor previously, that was for the motor control. Now we're talking about sensory. So for these regions first, let's look at the primary somatosensory. Where is that structurally?

You might notice here against our central sulcus, structurally that is in the postcentral gyrus. Okay so that's what you're seeing there. That's involved with associated with touch. So when we talk about the primary somatosensory cortex, we're talking about function. Okay if we talk about the structure, that would be our postcentral gyrus.

And then what we're also seeing here kind of two in one, we're talking about the sensory areas. We also have our visual, our primary visual cortex. And notice, please, this is in the occipital lobe.

So again, eyes in the back of your head. One right here. So we have our postcentral gyrus. Our postcentral gyrus is our structure. And then we have our primary.

somatosensory cortex, which is the function. Within our occipital lobe, our occipital lobe is the primary visual cortex and there's no specific defined region, it's just the occipital lobe is associated with the primary visual cortex. All right, so first look up at this little image. What you're seeing right there is essentially what looks like almost panes of glass that are going to be running within specific structures.

Now, if you remember, we had our central sulcus. And what that central sulcus does is it actually acts as a separation point between the precentral gyrus and the postcentral gyrus. Now, we also know now functionally that our precentral gyrus is associated with the primary motor cortex. And we also know that our postcentral gyrus is going to be functionally.

the primary somatosensory cortex. Now one is associated with our ability to have response with voluntary motor movement and the other one is to uh is associated with touch. Okay so as far as these regions um this is kind of an interesting map but it shows you how much of the cortex, remember it's only the cortex the superficial regions, is associated with those experiences we have in different regions of our body. Notice how much of our cortex we have associated with the face. So we have a lot of information coming to us from the face that we both want to be able to respond to and we want to experience.

Also notice here we have our tongue, so taste. We want to have a lot of ability to respond to eat things and to be able to taste things and that sensation. And kind of a fun one here too, I don't know if you notice, your toes and the foot are associated really closely with the genitals.

A lot of people have foot fetishes. So your... Cortices are kind of closely associated with one another that experience the sensations associated with those two regions of the body, which is kind of super funny.

This particular slide, you guys, is just an FYI so you have an idea of which part of each cortex is associated with what. I don't need you to know anything for this slide other than to kind of just give you an idea of what's going on. Okay, so moving on to the temporal lobe and to the insula.

So, the temporal lobe first. We're going to see that there's two regions in the temporal lobe that are going to have special cortices that are important for certain functions. First in black, this is going to be our primary auditory cortex that's associated with our hearing.

And then here in the dark blue, we have our primary olfactory cortex. Olfactory is our fancy word for smell. Now really quickly on your own head, I want you to think about where your ears are compared to your nose. Okay, your ears are going to be more posterior compared to your nose which is more anterior. Same thing with these.

So for your hearing, the primary auditory cortex is more posterior. For smell, your primary olfactory cortex is going to be more anterior. So that kind of helps you to remember where each one is located.

Finally, here we have the insula. And again, that's deep inside. That's where we're seeing that lighter color.

The insula I mentioned is associated with taste. So again, if you point inside of your mouth and go, ah, insula, that's going to remind you that the insula is deep. And it's also associated with taste. Okay, so let's add that really quick to our document.

So our insula. We have associated with taste, so let me get this, let me make sure primary, good, still in blue, primary, gustatory cortex. And then our temporal lobe, we have two locations, one that's more anterior and one that is more posterior.

If you think about your ears, your ears are going to be more posterior, so this is going to be our primary. auditory cortex and as far as smell we have our primary olfactory cortex. All right. So we can move on then to our association areas. Again, our association areas are for processing information, interpreting, also integration.

We talked about memories as well. Okay, so a couple different association areas that we have here. I know this looks a little bit confusing, but let me explain Wernicke's area that's in black. This is a larger region.

Okay, so what you're seeing in black, all of the black circle and what's within that black circle is Wernicke's area. Okay, notice that it's kind of at the border. between the parietal and the temporal lobe.

So it's kind of right there. If you were to track back with the lateral sulcus, just where that lateral sulcus ends, that's where you would find the Wernicke's area. And right smack in the center of Wernicke's area, that blue dot is the Gnostic area. So first Wernicke's area, that's going to be associated with our spoken and written language, the ability to comprehend it.

And then our Gnostic area is essentially taking all of the sensory, visual, auditory, kind of those different regions of the cortex that we saw previously. They're kind of in the same vicinity and it's integrating all of that information. So Wernicke's area and Gnostic area are right there in that same location.

So we have our Gnostic area in the center and Wernicke's area. A lot of what we know about the brain we've learned from people that have different mental disorders or kind of differences and the way that they're able to determine when a specific region of the brain was associated with a certain type of function is when that person had maybe trauma in that certain area of their brain. So there's some really great books I'll try and add it to our discussion page so you can check them out But there's some really great books about how we learned a lot of what we do know about the brain there's so much still that we don't know but what we've learned a lot of it has come from people that have had traumas or regions that were maybe malformed in development that have taught us what we know about the brain. Okay so moving on to the white matter. Okay so there is central white matter when we talk about white matter as a reminder those are going to be collections of axons of the CNS if you know to be tracts there's actually three different types of central white matter that we can talk about.

The difference in them is how do these axons run? Do they run from one hemisphere to another? Do they run within the same hemisphere from anterior to posterior? Do they run from the anterior part, kind of like the flower of the part, to the stem, to the brain stem? Those are kind of the ways that the different axons can run, and depending on the way that the axons run, we have a different type of central matter, white matter, associated with each one.

Okay, so first and foremost, an association track, that's what you're actually seeing here in the page. We're within the same hemisphere, so imagine that this is the right cerebral hemisphere. And we're running from anterior to posterior.

So that's going to be an association tract. We also have commissural. Commissural is going to be between the two hemispheres.

Now you can see the corpus callosum here, but its purpose is to run between, think about an axon connection, so it's coming out of the side here, coming towards the other side. That's going to be a connection point between the two hemispheres. So the corpus callosum that I've highlighted here is the biggest version of that. We're also going to find that there's anterior and posterior commissures. Those are smaller regions that do the same thing.

Okay. And then let's see what we have. Oh, perfect.

Okay. So commiseral, I was trying to tell you that that was the corpus callosum, but this is a better view of the commiseral right here. We can see it running from the left to the right side and vice versa.

Those are commiseral tracks. And then finally our projection tracks are the ones shown in green. So I mentioned kind of like running down the stem, like the flower to the stem.

So these are going to run anterior to posterior. Okay. So running from the cortex to the inferior portion of the brain.

So finally for our gray matter we have one more deep region and that's the cerebral nuclei. And within the cerebral nuclei we can define some of these. Now these, depending on the brain model, and I know that we don't have direct access to the physical brain models now, but these are deep structures. You would have to remove the cerebrum, but you wouldn't necessarily be able to see all of these structures if you were to slice down the longitudinal fissure.

So there's really great brain models that kind of remove the cerebrum. And you would want to look at underneath the cerebrum, you would be able to see these structures. Okay, so when we talk about the caudate nucleus, okay, so the caudate nucleus is what you're seeing here all in green. Okay, so all of this in green is a caudate nucleus. The caudate nucleus is how your arms and legs associate with one another while you're walking.

So the next time you get up, notice how your arms swing versus how your legs swing. And so that coordinated movement between your arms and your legs, that's your caudate nucleus. Now at the very end of a caudate nucleus, you have this cute little thing, it almost looks like a tail. That is called the amygdala or the amygdaloid body. Okay, so the amygdala and the amygdaloid body are one in the same.

One way to remember its function is angry Amy. So the amygdala or amygdaloid body is associated with emotions. So if you think of Amy being angry, that can help you to associate the amygdala with emotions. Okay. When we talk about the colostrum, the colostrum is going to be deep, so it would actually be deep inside.

That's going to be for subconscious information. So for the colostrum, maybe when you're thinking about going down the freeway, and you need to pay attention to what's directly in front of you on the freeway, so you're specifically focused on the lanes and making sure that the person in front of you isn't braking, and on your speed limit. Those are the things that are in your conscious information.

for the claustrum, it's taking the subconscious visual information that's coming on all the time. So for instance, if you're on the freeway and all of a sudden, like a building was on fire, if that was something that was alarming, now all of a sudden it would draw that into your conscious information. If you're driving down a street and a ball rolls onto the road, the claustrum would say, hey, there's something that is now something we need to focus on.

You would now bring that into your conscious information. So it's keeping track of all that subconscious information, letting you know when... the information is important enough to bring into your conscious uh to bring into the conscious um and then finally we have our putamen and our putamen is right here in blue and our putamen is for posture so i don't know if you remember learning about the i love spaghetti muscles those are the muscles that are going to run anterior excuse me superior to inferior down your back and help you to maintain your posture so i like to think of putamen love spaghetti so if you remember the I love spaghetti muscles and Putamen loves spaghetti, you can remember that Putamen is associated with posture. So that brings us to our diencephalon. Again, as a reminder, we have our primary and secondary brain vesicles that give rise to our diencephalon.

And we would need to do a dissection down the longitudinal fissure and open it up like we've been seeing to be able to see the diencephalon. So the diencephalon is going to include the thalamus, which is kind of smack in the center. That's what you're seeing kind of in this turquoise blue.

You have the epithalamus. Here we can see a little bit better. That's being represented here in orange. And then you have the hypothalamus, which is represented in purple.

So epi above, hypo below. And then at the very end, kind of tracking back behind the epithalamus, you can see the structure that I circled. That's called the pineal gland. Your pineal gland controls your circadian rhythm.

Maybe you've heard that serotonin is good to help you sleep. When lights go off, your brain is triggered to say, hey, it's time to sleep. And your brain releases serotonin so you can go ahead and go to sleep. So pineal gland is associated with circadian rhythm. Sorry, epithalamus and the, I got ahead of myself, the epithalamus and the pineal gland.

We have our thalamus. The thalamus has a little structure on the inside which is called right here the intermediate mass and that is going to be a connection point between the two hemispheres of the brain. You have the ability with the thalamus. I want you to notice this.

It does focusing and sorting of information. It's going to focus and sort and process and help you to process the information that comes from hearing, from vision, from taste. All of that information gets focused and sorted in the thalamus with one exception.

olfaction, your sense of smell. And the reason that is the case is way back when we didn't have, I guess when we were hunter-gatherers, we relied really, really heavily on our smell and our brain didn't want to take the time to process it, to focus it, to sort it. It was just going to be that first response. And so we actually don't take the time to focus and sort it in the thalamus like we do with our other senses. So that's why it's with the exception of olfaction.

All right. And our hypothalamus again is in purple. What you're seeing coming off of the purple hypothalamus is this cute little structure here, and that is called the infatibulum, and that leads to this hangy-bally thing that we see down here, which is called the pituitary gland. The pituitary gland and this connection between the pituitary gland and the hypothalamus, this is the major connection point between our central nervous system and our endocrine system. So we'll talk a little bit more about this when we get to the endocrine unit at the very end.

but that plays a major role in our endocrine system and controlling our endocrine system. On to the brainstem. So we have a couple different regions we want to be aware of. Let me see my pop in.

There we go. Perfect. When we talk about the mesencephalon, as a reminder, the mesencephalon, here's our secondary brain vesicle and it remains the mesencephalon. We have a couple different structures. Motor tracts.

Again, remind yourself what a tract is right now. I'll give you a second. Remind yourself what a tract is. Okay, so we have our motor tracts and we have our primary motor cortex leading down to our spinal cord. So these are the connection points that we have.

These are our cerebral peduncles. What we're going to do in this image is we're going to take the cerebrum and then we're left with this. So you can see the diencephalon at the top right here and here, which you're seeing in blue.

These are our cerebral peduncles. So those are going to be those tracks that we see. They're going to help us to connect and eventually make our way down to the spinal cord.

What we also have is our superior and our inferior cliculi. Now as a reminder, here's our corpus callosum. We have done a dissection down the longitudinal fissure so we can see the inner structures.

And here is our pineal gland. Here's our intermediate mass. Here's our thalamus. So what we're seeing if we go just below the thalamus, we have these two structures right here.

Now, what I want to tell you is we only have one hemisphere of the brain right here, and we only see one of each. These are both actually in pairs. So when I say colliculus, colliculus is singular, colliculi is plural. And so there are superior colliculi, meaning that there's two of the green structures.

There's one that's associated with each hemisphere, so that's why we only see one right now, though. And then there is inferior colliculi, meaning that there's two of these that are inferior as well. Now, for the superior colliculi. These are going to be visual reflex centers.

So think about your eyes. Those are going to be more superior versus your ears. If you think about where your eyes are versus your ears, your ears are going to be more inferior. So your superior colliculi, like your eyes being superior, those are associated with your visual reflex centers. Your inferior colliculi, like your ears being more inferior to your eyes, those are in charge of your auditory reflex centers.

Collectively, what we call them together is the tectal plate. So if we just pointed at one single region, superior colliculi, inferior colliculi, and then collectively together, tectal plate. This is another view. So remember, we've taken off the cerebrum. And so what you can see there, you can see highlighted back and forth, just so you can see.

Our superior colliculi are going to be superior. Our inferior colliculi are inferior. So eyes, ears. All right, we're moving down. And so what we just covered, here is our tectal plate.

And so moving down here, we're into the pons. Okay, so here's our pons. This is going to be bulging out. And like it mentions right there, it's the anterior side.

So this is the anterior side if you were kind of confused at where you are. We see that bulge facing anteriorly. Now, these are tracts. So these are going to be collections of axons. And what we're going to find is that there's some really, really important control centers here.

Here we have our autonomic respiratory centers. Now remember that when we talked about autonomic in association with the nervous system, autonomic is essentially automatic. Okay, you don't remind yourself to breathe, you just breathe.

Now there's a couple different things that we control with the pons in terms of our respiration. The rate is one thing that we control and the depth of the breathing. Now the pons and the medulla, these actually go hand in hand to be incredibly important as controlling the respiration. So we're going to actually find that the pons, when we say controls the medulla's effect on breeding, we're going to find the medulla is also incredibly important for breeding as well.

All right, moving down to the medulla, also known as the medulla oblongata. So it's this region we have right here just inferior to the pons. And we're going to find that there are two pyramids. These pyramids are motor tracks. So as a reminder, tract, a bundle of axons in the CNS.

What we find is that there's crisscross. So actually like the X, this decussation of pyramids means that they actually crisscross one another at this location. So that's what the decussation means is they crisscross these two motor tracks. That's what you're seeing.

That's from my previous slide. This is a crisscrossing interesting right here. So these are going to be those pyramids still on the medulla oblongata. It actually is considered absolutely essential for life because we control a lot of different things. Let me actually just start you down here at the third bullet point, the respiratory center.

This is going to work hand in hand with which structure that we just talked about. Do you remember? Okay, let's take a step back and remind you. Remember autonomic respiratory center that we find in our pons?

Yeah, so our respiratory center of our medulla oblongata is going to be working in tandem in order to be able to control the respiratory rate. So both of these structures work hand in hand with one another and then they're close in proximity to one another so that makes sense. But in addition to your breathing, cardiac center is going to help to control your heart rate and the strength of the contraction.

So how much blood are you going to be pumping out? Also vasomotor, when you see vaso think vessel. So vasomotor center actually helps to control our arterial diameter which helps to control our blood pressure.

We'll learn a little bit more about that when we get to blood. So as you can see heart, blood pressure, respiratory rate, the medulla oblongata is a key key structure in making sure that we stay alive. On to the cerebellum.

The cerebellum essentially is baby cerebrum or little cerebrum. And so in purple you can see the structure that we're focusing on. Just like the cerebrum, it actually has two separate hemispheres, a left and right side. Instead of saying cerebral hemisphere, we say cerebellar hemisphere because it's part of the cerebellum. The midline in between, we don't have a longitudinal fissure.

We have this little bulge. It's called the vermis. And the midline is actually important in and of itself. We're going to find that overall the cerebellum is important for things like your muscle memory.

So if you, when I tell you to maybe rewrite your answers for the exam or on your lecture objectives list over and over and over again, I'm helping to build muscle memory. We're actually going to use our cerebellum to have that muscle memory and to kind of call in on it. Also proprioception.

Proprioception is your understanding of yourself in space. So your awareness of yourself in space and how you exist in a space. So that's essentially what that is.

What is going to help us to separate? So if you look right here where I'm drawing the line. The separation point between the cerebrum and the cerebellum, that's called the transverse fissure. Okay, so this little separation point is called transverse fissure. If we look inside, so I'm going to cut, make a dissection right down the vermis, and I'm going to look inside one of the hemispheres.

Now I can see, notice that there's gray matter on the outside just like there is in the cerebrum. and there's actually white matter on the inside just like we see with our cerebrum. So the outer gray matter that is essentially our cortex so that's the superficial area that bumpiness that you're seeing on the outside of the cerebellum that's called the folia so those are folia that you're seeing all those little bumps. The white matter that you see on the inside is called arborvitae so the white matter all of this white matter is called the arborvitae.

And then finally, just like we had, and you can't really see it very well, so I'm not going to point it out on this slide, but just like we had the cerebral nuclei that were deep within the cerebrum, we actually also have deep cerebellar nuclei. So these are going to be nuclei, collections of soma, but instead they're in the cerebellum, so they're called cerebellar nuclei. For this part here, we have, what we're going to focus on is our ways that we support the brain and protect it.

And so when we talk about this, we're going to talk about various layers of connective tissue that are going to help to support the brain and protect it in that way. When you think about it, think about the cranial cavity and all these cranial bones that are making up the cranial cavity. That's really hard structure and so we need to have some kind of separation protection.

So not only do we have connective tissue and we're going to identify these different layers, but we're also going to find that there's fluid that's going to surround the brain. So it's almost like the brain's floating in like on a waterbed or something like that. So it gives it the ability to be a little bit more protected.

Now, when we say cranial meninges, these are the layers of connective tissue that I'm going to talk about. Meninges is plural. Meninges is singular. OK, so if you see menings on your lecture objectives list, that's singular.

Meninges is plural. And again, it's going to provide us all of this protection and these layers. Now, the three layers that we're going to see are the dura mater, the arachnoid mater, and the pia mater. The arachnoid mater, we're going to see actually there is kind of some cobweb-y looking stuff. It's kind of how the connective tissue looks.

And so that's going to be the arachnoid mater. And then we have our dura mater and our pia mater. So notice on this skull, we're actually seeing a cross-section.

Where we are right here is we're going to be... in this location first that I want to draw your attention to. So this location that we're in right here is where our two parietal bones would meet.

So we're at the very top. What we're seeing here is our cortex. And in between this space right here, you're seeing between these two sides, the left and right side, this invagination is actually going to be our longitudinal fissure.

So the longitudinal fissure is the invagination of the brain we're seeing. Now what I want you to notice is when we talk about these different layers, these different layers are layers of connective tissues that are layered right on top. We're going to start from the most superficial and then make our way more deep. Now the dura mater, let me change my colors as I go, the dura mater actually has two sub-layers. There is one layer that is called the periosteal layer, and there's another layer that's called the meningeal layer.

Now let's think about this. So let me just highlight for you where the first layer is. Here's our first layer right here. That first layer that I just highlighted, that is our periosteal layer. Now what comes to mind when we say periosteal?

Any idea? Hopefully periosteum and hopefully bone. So the periosteal layer is the layer that is closest to your bone. The meningeal layer Let me show you this.

Now it's a little bit different. Watch. I'm going to come along the bone, that periosteal layer, but then I'm going to dive down.

See it? Diving down that longitudinal fissure. Then I'm going to dive and then come back up.

So the difference between our meningeal layer and our periosteal layer is how they run. The periosteal layer is more superficial and it's just going to run right along the bone. It's not going to dive in with each crevice, each nook and cranny of the brain. However, the meningeal layer, let me just add that here, our meningeal layer, It is called the meningeal layer because it's closest to the other meninges, so that's why it gets its name.

It's actually going to dive down. Now, it doesn't follow every nook and cranny of the brain, but it does follow with the major fissures. So you do see that diving down as you see here. Now, what is between the two layers?

I want you to notice right here in the blue, that region right there is called the dural sinuses. Now, when we say dural sinuses, we are specifically talking about blood vessels, and we're talking about blood vessels within the brain. And so in between this blue... space that we're going to see here, we're going to find that that is where we're going to find our dural sinuses. So I'm going to draw, not right inside of one, but kind of in between.

I'm going to draw just kind of like a little rectangle right here. That's not good. There we go. And that guy is our dural sinus. Now there's many dural sinuses, so we're just getting an example of one that would be there.

What we're going to see in the brain, the reason why I say in the brain specifically is because when we get to the spinal cord, we're going to find that there's slight differences in these spaces. Okay, so at least for the brain, we're going to find that there is potential epidural space and there is subdural space. Now let me explain that. If I say epidural, epi means above the sinuses.

Okay, so epidural means above the sinuses. There is only potential epidural space. There is no actual space there, but there's potential for there to be space.

Why would we need space in the brain that we don't have right now? Well, if you were to start to have bleeding of the brain, swelling of the brain, your brain isn't draining the way that it's supposed to. That means then we do have a little bit of space that can be filled, and that would be the epidural space that we would move into.

So that's why it's potential epidural space, but as it exists normally. you don't have that epidural space open. We do however have subdural space.

So we will have space below and and that's going to be with things like cerebral spinal fluid. So we'll talk a little bit more about that in a second. Next up we have our arachnoid mater.

Our arachnoid mater is going to be, let me do a different color, our arachnoid mater is going to be all of this that we see with kind of that cobwebby stuff. Okay so this is all our arachnoid mater. It is deep to our dura mater and specifically deep to the meningeal layer of the dura mater.

And what we're going to find is within this cobwebby space, all of this, we're going to have CSF, cerebral spinal fluid. So if we have our cerebral spinal fluid, well, that's perfect that it's in that location because it's going to help to cushion the brain and prevent it from running into our bone. But also what I want you to notice is these little projections that are coming into the area where the dural sinuses are.

These little projections that we see of the arachnoid mater are called arachnoid villi. Villi is plural. Villus is singular. These little projections are going to be our points at which we can have flow from the cerebral spinal fluid to the sterile sinuses.

This is how we connect back to our vessels so that we can keep the flow of cerebral spinal fluid flowing through the brain or around the brain. So that's the arachnoid villus. This is a special structure that is part of the arachnoid mater. And then finally, we have our pia mater.

Our pia mater is going to be the deepest meningeal layer. And we're going to find that this is this tiny little layer you see me highlighting right around the brain. It follows every single nook and cranny, every sulcus, every gyrus.

So this is going to be our pia mater. And the pia mater is made of areolar connective tissue. And that areolar connective tissue, you might remember, it provides strength and it also provides binding.

And so it binds right down, almost like shrink wrap, right over the top of the brain. So one of the things I mentioned was the dural sinuses. When we talked about, talk about septa, if you think about a septum, for instance you have your nasal septum, that is a separation point between, for instance, your nose and the two nasal passages. The septa, or these divisions, are going to be separation points, and then we have our sinuses which are going to be specific vessels that we see in certain regions.

So first let me just show you this table right here. This is what I want you to know for lecture. So you have a septum.

Where that septum is located is going to be the second part of the table. And then the sinuses, the vessels that run within that region, is listed next. So let me just show you one example first.

Our longitudinal fissure, I've been showing that a lot to you. That is going to be directly between the two cerebral hemispheres. What the septum is called is the Fulx cerebri.

And the sinuses that we see there are the superior and inferior sagittal sinuses. So let me go ahead and show that to you. This area right here is the fulx rebri. You're only seeing half of the brain or kind of where it would be.

Here you would only have the right hemisphere still intact. So here is the septum. We're right here within the longitudinal fissure. And let me just show you here, highlight in the blue. Right here in blue, hopefully you can see it, you have a superior sagittal sinus.

And then right here in blue you have the inferior sagittal sinus. So those are the two sinuses. So see with this location again we're in the longitudinal fissure and that's the Fulx Cerebrae.

Here is another example. This is actually with the brain. You wouldn't be able to see the inferior sagittal sinus because it would be deep inside, but you can at least see the superior sagittal sinus.

And again that's running within the Fulx Cerebrae. Tentorium Cerebelli. Hopefully you hear in that cerebellum.

Where is this going to be? At the transverse fissure. As a reminder our transverse fissure is that separation point, it's that invagination that's going to be between the cerebrum and the cerebellum. And what we see there is there's a straight sinus and a transverse sinus. Now the transverse sinus, hopefully you can see it right here, runs transversely.

So this is our transverse sinus. And again, what we call that septum is the tentorium cerebelli. And I think...

perfect, okay. Our transverse here is running around, kind of around the edges. Our straight sinus is medial, so I want you to notice it's kind of like it's almost somebody's poking you directly in the back of the head.

This will be our straight sinus right here. Our Foulk's cerebelli, that's going to be essentially near the vermis. It's between the two hemispheres of the cerebellum, and there we have our occipital sinus.

I have the Foulk's cerebelli right here, so you can at least see where that location is. Yeah, perfect. Okay, so here's our Foulk. Fulcera Belli, and there's the occipital sinus right there.

Okay, so you can see the occipital sinus right there. And then finally we have our diaphragm of cilia. Do you remember learning about the celloturcica? Here's where it comes back. So what actually sits in the celloturcica, it's not you riding a butterfly into the sunset, but instead what sits there is actually the pituitary gland that we just learned about.

So right within that septum, the diaphragm of cilia, we find the cavernous sinus. Think about it being like in a little cave. So here's our diaphragma cilia.

Here's our pituitary gland, diaphragma cilia. And I believe it's this vessel right here. So that would be our cavernous sinus. Okay, so just make sure that you're able to associate each of the different septa with the sinuses that would be in that location.

And that's what I need you to know for lecture. So as far as the brain ventricles go, this is not what I was talking about with the primary and secondary ventricles. This is those are vesicles.

This is entirely different. These are ventricles. So when we talk about these regions, what we're going to have is essentially cerebral spinal fluid. That's going to be able to circulate in and around the brain.

And we're going to find that there is actually a connection point where we are going to empty back into venous flow into our dural sinuses so that we can continue to have that flow go through. So think almost like a, I'm thinking of like a fountain pump that keeps the water flowing through a fountain. We have this continuous flow between the circulatory system and the cerebral spinal fluid.

These are the brain ventricles. And so the brain ventricles you're seeing in blue, they're weirdly named and weirdly numbered. So let me just explain and walk through. Okay, so if you have your lateral ventricles, there's one on the left and right side, and that's why they're called your lateral ventricles.

And then this is them from the lateral view. So there's your lateral ventricles here, which I want you to see is then you're going to go into your next one. Now, I guess maybe because the lateral ventricles were considered first and second. But anyways, we go from the lateral ventricles, and the next place we go is to our third ventricle. Okay, so third ventricle is next.

From there we're going to go into a structure called the cerebral aqueduct, and that's kind of like our little connection point between the third ventricle and the next one. So this is our cerebral aqueduct, and the next one that we have is our fourth ventricle. Okay, so it goes lateral ventricles, third ventricle, cerebral aqueduct, and then fourth ventricle. So I want you to notice the locations of these.

The lateral ventricles are located within the cerebral hemispheres. Where we find the third ventricle is right in the location of where we have the diencephalon. Our cerebral aqueduct is going to help us to connect to the brain stem, and then we're going to see that the fourth ventricle is within the brain stem and the cerebellar region.

All right, so for our final slide, we are going to go over the flow of the cerebral spinal fluid. You're welcome to walk through it on your own afterwards if you would like. Basically, wherever you see these squiggly lines, We are going to have what's called choroid plexus. Choroid plexus, you might remember, is associated with the ependymal cells. And the ependymal cells, their function as glial cells are to help to make CSF or cerebrospinal fluid.

So what we're essentially having is as we make our way through this process of kind of working our way down the ventricles, we're going to get infusions of fresh CSF as we go. We're going to start in the lateral ventricle and we're going to get an infusion of CSF there. with the choroid plexus. That CSF is then going to flow down to the third ventricle and we're going to get a fresh batch of CSF in the third ventricle. We'll then make our way down the cerebral aqueduct to the fourth ventricle where, you guessed it, our choroid plexus is going to give us a fresh batch of CSF.

And then we're going to be able to make our way out. Here it shows you kind of to the lateral apertures and the median apertures. This is where we're going to actually make our way finally into the subarachnoid space. The subarachnoid space is going to be associated with our arachnoid water and that is where we have the CSF that's going to flow around the brain.

So all these arrows in black that you're seeing after that is flowing CSF around the brain. Finally you might remember the arachnoid villi so let me just draw your attention up here to eight. That's the arachnoid villi where we have the connection points with our dural sinuses. These are actually veins that we're going to dump the CSF into after we have had it flow around the brain. So essentially with creating new CSF we provide fresh nutrients, we provide fresh fluid to go around the brain.

Then as that fluid goes around the brain, it's going to start to collect more and more of the waste products of the brain. And so we can dump that back into the vena circulation when we're done with it, continue to get fresh. So that's essentially how we have this take place.

All right, that is our lecture for the brain.

Transcript for:Understanding Brain Structure and FunctionCH15

Transcript for:
Understanding Brain Structure and FunctionCH15