Hello everyone and welcome back. In this section we begin an examination of
the nervous system looking at it from a schematic point of view in the form
of a spreadsheet. I strongly suggest that you print this spreadsheet out
and use it to keep track of different brain areas and the structures that go
along with it.
So let’s begin by looking at the major divisions,
structures, and assorted other things that go along with the brain. As you
can see, there’s a variety of different words here that you’ve probably
never heard before; proencephalon, telencephalon; on and on. The word
encephalon means brain, and the wording in front of it tells you what part
of the brain that you’re looking at. For example, proencephalon means
forebrain while telencephalon means end brain. So let’s look at the
different structures located in the brain.
The first thing that I would like you to do is get a
baseball hat. Now that you’ve got the baseball hat I want you to take your
hand and stick it out in front of you. Then I want you to make a fist. In
this case, the arm represents the spinal cord and the structures at the top
of that within the fist represents the structures that are located within
the first initial division of the brain called the hind brain. Now, what
I’d like you to do is take your hand and wrap it over the top of your fist.
The hand over the top of the fist represents the next major set of
structures that grow on top of the hindbrain. These are called the midbrain
structures, of which there’s a wide variety. We’ll talk about them in a
minute.
The next thing I’d like you to do is get the hat and put
it over the top of the other stuff. The hat represents all the structures
that are within the forebrain. As you can see, there’s a wide variety of
structures within the forebrain (including two major divisions). We will
talk about these in a minute. So, this is what you see when you look at the
brain. The brain basically consists of one group of tissue growing on top
of another group of tissue and growing on top of a third group of tissue.
The tissue, then, differentiates into a variety of structures and
sub-structures. These are the things that make up all the different
structures that we have to memorize.
So, let’s start by going to the very bottom of this sheet
and looking at the initial and major divisions of the brain, and some of the
structures and sub-structures that are located within it. Let’s start with
the spinal cord. Again, the spinal cord is basically a bunch of nerve
fibers that are connected to the hindbrain. The hindbrain or
Rhombencephalon has two different major divisions. These are the
Mesencephalon and the Metencephalon. The Rhombencephalon is basically what
we call the Medulla, while the Metencephalon consists of structures within
the Cerebellum and Pons. As you can see there are some sub-structures in
the cerebellum as well.
As we go a little bit higher in the brain, we move into
the midbrain structures. What we see is called the Mesencephalon. The
Mesencephalon consists of a couple major groups of major structures such as
the Cerebral Peduncles and the Quiadrigeminal Plate which consists of
sub-structures. We’ll talk about each of these as we talk about specific
brain structures in the hind, mid, and forebrain areas a bit later.
The next major division that we have consists of the
Telencephalon and the Diencephalon. The Diencephalon is the inter brain and
it consists of a different structures including the thalamus, hypothalamus,
and others. Each of these are extremely, extremely important. The
telencephalon also consists of major structures and sub-structures.
Primarily what you commonly think of the telencephalon is the cortex or
outer part. However, there’s a wide variety of other end brain structures
as well including Basal Ganglia and the Olfactory system. So again, each of
these major divisions have major structures and sub-structures as well.
Let’s now move back to the bottom of the page again and
look at the ventricles. Let’s again start from the bottom. As we see, that
the 4th ventricle works in both the hindbrain and some of the lower midbrain
structures. But primarily within the midbrain we have the cerebral
Aqueduct. This structure is going to drain the 3rd ventricle into the 4th
ventricle. The 3rd ventricle primarily is located within the Diencephalon.
Finally, the lateral ventricles (ventricles 1 and 2 or the left and right
ventricle) are basically are in the telencephalon area of the brain.
The final set of structures listed here are called
circumventricular organs. These structures have a wide variety of different
structures. As you can see, they are listed and located within the
different parts of the brain. Most of these structures are related to
endocrine activity or monitoring of different brain and blood hormones. We
also have other structures within these systems that are going to regulate
salt intake and how much water we have.
So, in conclusion, this overview gives you a good breakout
of the major structures and sub-structures that we have in the brain. Of
course there are many, many other structures that could have been included
as well. You can do that if you wish. But for right now, what I’d like you
to get an idea of where these major groups are. This spreadsheet will help
you a little bit as you are studying the brain structures in DeArmond et al.
In the next sections, we’re going to begin talking about
the different groups and divisions within the brain. That is the hind
brain, mid brain and spinal cord, etc. Next time we will begin talking about
the hindbrain. So until then, we hope you have a good day and we will talk
to you soon.
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