So I mentioned in the last video that I was
going to go over the level three objective, focused on the primary and secondary structures
that lead to the mature structures in the adult brain. And so there are these two slides
that are used to to meet that level three objective. For this slide that you see right
here, each of the major bullet points is going to be what we consider the secondary brain
vesicle. That's what we're seeing here. And then listed underneath it is the —are the
mature structures that are going to result from that secondary vesicle. As I mentioned,
the last video ended with ventricles and that's not to be confused with these brain vesicles
which are the different embryonic structure structures that lead to the mature brain.
So let's go through each of these. I want to just kind of show you how these arrows
work. So everything's going to start with our neural tube and then we're going to develop
into these three different brain vesicles. We're going to ignore the neural canal for now. We're
going to either mature into the prosencephalon, the mesencephalon, or the rhombencephalon. The
prosencephalon then further differentiates into either the telencephalon or the diencephalon.
Our mesencephalon remains the mesencephalon, and the rhombencephalon becomes either the
metencephalon or the myelencephalon. So hopefully that is starting to clear things up for you. The
telencephalon becomes eventually the cerebrum. And we know the cerebrum now from the past video
to be all of the various lobes and that's the largest part of the brain that we associate
with. The diencephalon remains the diencephalon. To remind you what those are, those are going
to be the thalami. The thalamus, epithalamus, and hypothalamus. The mesencephalon becomes the
brain stem. But the brain stem specifically or the brain stem and just seeing the brain stem
is not specific enough. You're going to notice that there's parts of the brain stem for the
metencephalon and the myelencephalon too. So when we say mesencephalon, specifically the parts that
are going to be created from that mesencephalon are going to be the peduncles and the superior
and inferior colliculi. For the metencephalon, that's going to form not only the cerebellum but
the pons. So specifically the ponds of the brain stem will result from the metencephalon. And then
our medulla oblongata is going to result from the myelencephalon. So for the brain stem components,
you want to be able to be more specific since these different secondary brain vesicles are going
to lead to different structures within the brain stem. Now let me go through and erase all of
this and just kind of walk you through, color coding so you can kind of keep track and each one
separate. So say I gave you an exam question and I asked you, what are the primary and secondary
brain vesicles for the cerebrum? You would say, for the cerebrum that our primary brain vesicle
is the prosencephalon and the secondary brain vesicle is the telencephalon. Let's go ahead and
change colors here. If I asked you on an exam, what are the primary and secondary brain vesicles
for the thalamus or diencephalon? Our primary brain vesicle would be the prosencephalon
and our secondary brain vesicle would be the diencephalon. I could also ask you, how about
for the superior and inferior colliculi? What are going to be the primary and secondary
brain vesicles for that? Or I could ask you what about the cerebral peduncles? You
would give me the primary brain vesicles are the mesencephalon and the secondary
brain vesicle is the mesencephalon. So, remains the mesencephalon. If I ask you primary
secondary, because they're the same name you would give me that twice or I would list it
twice in a multiple choice question. For our pons or cerebellum, our primary brain vesicle is
going to be the rhombencephalon and our secondary brain vesicle is the metencephalon, okay. So
that will give us our ponds or our cerebellum. Finally, we have our medulla oblongata. If
I asked you in an exam question what are the primary and second secondary brain vesicles for
the medulla oblongata, you would give me primary brain vesicle rhombencephalon and secondary
brain vesicle myelencephalon. So there you go. And oh just uh just as a reminder, feel free
to associate with these but notice that they're only going to be the secondary vesicles. They
don't list the primary and I need you to know the primary as well. And also as a reminder on
the previous slide and your brain lecture slides, almost every single title slide where I
introduce a new structure. You see listed before that the primary and secondary
brain vesicle, okay. There you go.