Alright. So in this video, we're going to be talking about the development of our central nervous system. And CNS development really begins with the neural tube. And that is the embryonic structure that eventually becomes the CNS. So this literally starts off as just one tube and what happens is the anterior end will eventually kind of form, it'll begin to grow and it'll form vesicles. And then the caudal end of that tube or the inferior end will eventually become our spinal cord.
So for the remainder of the video, we're going to go over those three primary brain vesicles and we'll talk about what structures they eventually mature into in the adult brain. So the first primary brain vesicle is the prosencephalon and this is also called the forebrain. Directly below that we have the mesencephalon, which is also called the midbrain. And then below that we have the rhombencephalon. And that's also called the hindbrain.
So, if we look at our little embryo here, the one labeled early embryo, this is what it's going to look like between the 3rd and 4th week of development. So you can see we already kind of have these little constrictions kind of bubbling out and we have our forebrain, midbrain, and hindbrain beginning to form. And then right inferior to that we have the part of the neural tube that will become our spinal cord. And you can see this one labeled late embryo here this is what it looks like by about the 5th or 6th week of development. So you can see it's already beginning to really kind of grow and expand out and we're seeing that very characteristic folding that allows our brain to fit into our skull. So that's already happening by about week 5 of development.
Now, in terms of what structures these are going to mature into, what we see is that the prosencephalon or the forebrain is going to mature into the cerebrum as well as the diencephalon. The mesencephalon or the midbrain will mature into the midbrain which is one of our brainstem structures so that one's kind of easy to remember. And then the rhombencephalon or the hindbrain will develop into 2 brainstem structures. We have our pons and our medulla oblongata and it also matures into the cerebellum.
So if we are looking at our mature mature brain down here, to kind of give you a better sense of where these delineations are, if we draw a line right about here like we did in the previous video, everything above that, the cerebellum and the diencephalon, is our forebrain. And then right smack in the middle of the brain, again this one's kind of easy, that's our midbrain, and then everything below that line is our hindbrain. So we have our pons, our medulla oblongata, and our cerebellum there.
So you can see even though we often think about and talk about the brain and spinal cord as being these separate structures, you can see how they really are just one continuous structure. And that's how they start in embryonic development. And even as they grow and mature and become much more complex, that's really how they stay. They are one continuous structure and that is, of course, our central nervous system. So I'll see you guys in our next video to talk even more about the CNS and talk more about the cerebrum. See you there.