Okay, so moving on to chapter 12, we're going to talk about the central nervous system. The central nervous system includes the brain and the spinal cord. The last section, we'll kind of talk about the spinal cord, but most of this chapter, we're going to focus on the four regions of the adult brain and what are the functions of the specific areas. So for chapter 12, if you notice, this PowerPoint only includes like 60 something slides. Your textbook is very dense, meaning it has so much information in it that you are not responsible for.
So when filling out the worksheets, I recommend that you are putting the function in as presented to you in these slides for chapter 12. Outside of the slides, again, way too much information. The worksheets on the four regions of the brain will make up the bulk of the material from this chapter that you'll be tested on, but there are some other things that we're going to talk about. So don't completely ignore the PowerPoints and just focus on the worksheets.
Kind of use the worksheets to help collect all the information for the regions and the specific areas, but still study the other information that's in these slides. Okay, so before moving on to the specific regions and areas, we're going to talk just briefly about embryology. So what's going on? So the brain and the spinal cord begins as a neural tube and then the neural tube has two ends.
So the tube is going to have an anterior end and it's going to have a posterior end. The anterior end kind of develops and it's going to form constrictions or like indentations in it. These indentations or constrictions end up forming the three primary vesicles.
So our three primary vesicles are going to be the proencephalon, which is also called the forebrain, the mesencephalon, which is also called the midbrain, and the rhombencephalon, which is also referred to as the hindbrain. The posterior end does not develop into any primary vesicles. Instead, it's just going to form our spinal cord.
Okay, so that neural tube that we were just talking about that has the anterior and posterior ends, the anterior portion, like I mentioned, is going to develop into three primary vesicles. So that's our proencephalon, mesencephalon, and rhomboencephalon. Well, these primary vesicles will further develop and form our secondary brain vesicles, and then eventually our adult brain structures.
So you do need to kind of understand what everything is developing into. I will say you do not need to worry about the adult canal regions. But for example, you need to know that the proencephalon becomes the telencephalon and the diencephalon specifically.
Mesencephalon is the easiest one to kind of understand what's going on because it doesn't change. So the mesencephalon as a primary brain vesicle remains the mesencephalon. as a secondary brain vesicle.
And then our third primary vein vesicle, the rhombencephalon, will develop into the metencephalon and the myelencephalon. You should also kind of understand what's being developed when we're talking about adult brain structures from the secondary brain structures. So if we're talking about the telencephalon, that's going to be our cerebrum.
Our diencephalon is going to remain our diencephalon as an adult brain structure. You'll learn later that our diencephalon is composed of the thalamus, the hypothalamus, and the epithalamus. And then we have our mesencephalon, which becomes a component of our brainstem, or more specifically, our midbrain. Our other two components of our brainstem are pons and our medulla. are going to develop from our rhombencephalon.
So our metencephalon if we're talking about pons and our myelencephalon if we're talking about the medulla oblongata. And as I mentioned previously, the posterior end of the neural tube is just going to simply develop into the spinal cord. It doesn't form primary or secondary brain vesicles.
So we're focused on the adult brain. not really so much the embryology, that image that I just showed you, that's the only thing you're really responsible for as far as neuronal development. Here, we're going to focus on the four regions of the adult brain and then the specific areas and their functions within each of these four regions. And as I mentioned, your textbook can get overwhelming with this information.
So just focus on what I have. in the slides because that's all you're going to be tested on for this chapter. So before we can actually start talking about individual regions of the brain, Let's talk about the brain tissue itself. So if we were to take a section of brain tissue, we would notice that it has kind of a pattern. And the pattern is dark areas and light areas.
And the dark areas we refer to as gray matter and the lighter areas we refer to as white matter. It's not just randomly, you know, color to different color. These specific... Regions have specific things in them. So when we're referring to the gray matter that appears darker in brain tissue, this is composed of non-myelinated neurons as well as cell bodies of neurons and cells.
We're talking about white matter. We're talking about mostly myelinated axons. Okay. There are a few non-myelinated axons, but your primary focus should be myelinated axons. And the reason why it looks lighter in appearance and we call it white matter is because myelination is a really fatty substance and it looks white.
So it appears whiter and that's why we call it white matter. So if we're talking about distribution of white matter and gray matter in the central nervous system. There are kind of patterns depending on where we are. So that's what we're going to talk about now.
So if we will take a cross section of our spinal cord that's shown to you right here, the basic pattern for gray and white matter is that gray matter is found in the center. So it's centrally located. It kind of looks like a butterfly. We'll talk more about that in lab. And then surrounding the gray matter, we have white matter.
As we ascend and reach the brainstem, the gray and white matter composition changes a little bit. We still have a little bit of gray matter in the center, surrounded by white matter, but we also have gray matter that's kind of scattered within the white matter. So we can see we have gray matter out here. These are just what we refer to as nuclei. And then as we reach our cerebral hemispheres, our pattern further changes.
Most of the gray matter is going to be located on the exterior portion. This is what we refer to as the cerebral cortex. So the outer edge, the most superficial portion of the cerebral hemispheres is composed of gray matter.
Then we have centrally located white matter. And then again, scattered within that white matter, we have some gray matter that we can see, which we refer to as brain nucleus. nuclei.