Original subtitles

You may not even realise it, but as

you're using your laptop to study, your computer

is exchanging and processing information using a binary

code of 1s and 0s.

For example, when you type in skull into

Kenhub's search bar, your computer uses this cryptic

language to receive information from the website.

This allows you to read articles, watch videos,

study illustrations and test your knowledge.

Your brain works very much like a computer

in that at its most basic level, it

too uses a binary code of sorts.

It either sends an action potential along a

nerve or it doesn't.

And this is what makes us capable of

completing everyday functions like digesting your food, contracting

your muscles and facilitating vision.

Yep, our brains are definitely one mega supercomputer

and we could spend days or even years

talking about all of its capabilities.

But today we're going to start with the

basics as we look at an introduction to

the brain.

Before delving into the details, let's take a

minute to introduce what we'll be learning today.

We'll start by taking a general overview of

the brain and see how it fits in

with the rest of the body.

Specifically, the relationship between the central nervous system

or CNS and its peripheral counterpart will be

examined.

This will give us a really good idea

of how the brain acts like the computer

we saw in the beginning.

Next, the different functional components of the brain

will be examined, starting with the three parts

of the brainstem which control the lowest, most

basic bodily functions like breathing and heart rate.

Next up, we'll investigate the cerebellum and we'll

see how it helps you with your smooth,

fine motor movements like what you would use

in the dissection lab.

Then we'll ascend, both in position and function,

to look at the different parts of the

diencephalon.

This part of the brain does many things,

including acting as a mediator for the nervous

system by receiving and processing information, then sending

it where it needs to go.

Finally, we'll reach the large convoluted mass that

constitutes the cerebrum or the telencephalon.

And as we'll see, this is where the

most advanced functions take place like critical thinking

and voluntary muscle movements.

We'll also see how the cerebrum is organized

into two hemispheres which are each made up

of various lobes that have their own unique

function, but more on that later.

Finally, we'll put on our white coat and

look at what we've learned from a clinical

perspective.

So before getting into the nitty-gritty details,

let's see where the brain fits in as

an integral part of the nervous system.

So if you've been surfing our site, then

you may already be familiar with this stimulating

ins and outs of the nervous system, in

which case you already know that the brain,

along with the spinal cord, belongs to the

part of the nervous system known as the

central nervous system.

Here is where you find components that are

essential to the functioning of the human body,

many of which will be covered in this

tutorial.

Outside of the CNS, like out in the

limbs, is where you find the peripheral nervous

system, which continually communicates back and forth with

the CNS.

Now the CNS, especially the brain, acts like

a conductor as it controls the orchestra of

signals that regulate the secretions, movements, and excretions

all over the body.

These signals are sent out via efferent motor

nerves, much like how the computer at the

beginning used its binary language to send out

commands across the network.

The brain not only uses the peripheral nervous

system to send messages, but also to receive

them.

For example, peripheral sensory nerves from your feet,

eyes, and skin tell your brain that the

sand is soft, the sun is bright, and

that jumping into the ocean on a nice

hot day feels so refreshing.

We call the nerves that carry these signals

afferent or sensory nerves.

This, of course, is just the beginning of

the story.

Let's get into the good stuff and see

what this organ is really capable of, starting

with the brainstem.

To see the brainstem, we'll use this mid

-sagittal view, which is as if we cut

the brain down the middle and looked at

its internal structure.

This little guy might not look like much,

but in actuality, your brainstem is essential to

your survival as it regulates our most basic

functions to stay alive.

It's also responsible for acting as a relay

or highway for those sensory signals we saw

earlier that are going up to the cerebrum

and motor signals heading down and out to

the periphery.

The brainstem is made up of three separate

parts, which are the medulla oblongata, most inferiorly,

the pons, which is this middle part of

the brainstem that appears to be bulging out,

and finally, the midbrain, situated at the most

superior aspect of the brainstem.

Let's go ahead and look at each part

in a little more detail.

The medulla oblongata, or sometimes just referred to

as the medulla, is the most inferior aspect

of the brainstem and is immediately superior to

the spinal cord.

The medulla is responsible for regulating some of

life's most basic functions, like breathing, dilating and

constricting blood vessels, and swallowing.

Next up, we have the pons, found immediately

superior to the medulla.

This part of the brainstem is appropriately derived

from the Latin word for bridge as it

spans the two halves of the cerebellum, which

we'll look at in just a minute.

It also plays a role in regulating your

sleep cycle, so please limit your all-nighters

and give your pons some rest.

The third and final and most superior part

of the brainstem is the midbrain, and it's

here where integration of sensory input from the

periphery and motor output from the cerebrum occurs.

To put it simply, this is what tells

you to move when there's a bus that's

about to hit you.

Next up, we have the cerebellum.

So many moons ago, an anatomist studied the

cerebellum and thought this small ovoid mass of

gray and white matter sort of looks like

a little brain.

And thus, the cerebellum got its name.

You can find the cerebellum hiding behind or

posterior to the brainstem, which we just looked

at, and the cerebellum helps maintain muscle tone,

balance and posture by sending out involuntary signals

to your peripheral nervous system.

This means that you have no conscious control

over these signals and it happens automatically.

The cerebellum also helps with fine, voluntary coordinated

movements, which you do have control over.

And these movements will come in handy for

looking at some deeper brain structures in our

next section.

But for the moment, let's use our cerebellum

to pick up the scalpel, carefully dissect a

little deeper and check out the next area

of the brain, the diencephalon.

This part of the brain is located deep

inside, between the brainstem below and the cerebrum

above.

Therefore, you may hear the diencephalon sometimes referred

to as the interbrain, since it connects these

two major portions of the brain.

Its position allows it to work as a

relay center by processing and directing signals for

sensory information and autonomic functions between the brain

and the periphery.

You can almost think of it as a

central hub for the brain that helps coordinate

different systems.

The diencephalon itself contains many parts, including the

thalamus, which is the largest part of the

diencephalon.

And just inferior to the thalamus is the

metathalamus and the posterior part of the pituitary

gland, which is intimately related to the endocrine

system.

As you could probably guess, the diencephalon is

very functionally diverse, since it works between so

many different systems, but we're just offering an

introduction here.

Of course, for more details, go ahead and

check out our page dedicated to all things

diencephalon.

Okay, and finally, we come to the largest

and most functionally complex part of the brain,

the telencephalon.

To make studying this three-pound organ a

little easier, we're going to be dividing it

up into its various lobes.

So keep in mind that all of these

lobes that we'll look at are bilateral, meaning

they have both left and right counterparts, one

in each hemisphere.

And these include the frontal lobe at the

most anterior aspect, and posterior to the frontal

lobe, we'll have the parietal lobe, and all

the way at the most posterior aspect of

the brain is where we'll find the occipital

lobe.

And finally, we'll check out the temporal lobe,

which is situated near the ears.

Let's dig a little further and see what

each lobe is capable of, without even realizing

it, you've actually been using your frontal lobe

quite a bit throughout this tutorial to help

hold your attention, keep you motivated, and engage

you in critical thinking.

Also contained within the frontal lobe is this

prominent ridge called the precentral gyrus, which contains

the primary motor cortex.

But don't let these big words overwhelm you,

the take-home message here is that this

area controls voluntary muscle movements, which allows you

to do some pretty awesome dance tricks.

Finally, one last important function of the frontal

lobe is the production of speech, which is

specifically orchestrated by a region known as Broca's

area.

Immediately posterior to the frontal lobe is the

parietal lobe.

It's in this part of the brain where

language processing occurs.

Without this vital piece of brain tissue, you'd

have no idea what I'm saying, and I

might as well be speaking an entirely different

language.

Also located in the parietal lobe is the

postcentral gyrus, which contains the somatosensory cortex.

Compared to the motor cortex that we saw

in the frontal lobe, the somatosensory cortex controls

all sensory perception that's coming in from the

periphery, which is how you felt the fine

sand between your toes while walking on the

beach.

When you see the occipital lobe, you should

immediately think vision.

Though you're right, it does seem a little

counterintuitive that the most posterior part of your

brain is what controls and processes information from

your eyes.

I guess maybe we do actually have eyes

on the back of our head.

To wrap up the telencephalon, let's have a

look at the temporal lobe.

One main function of the temporal lobe is

the processing of auditory information that is received

from the ear.

Unlike the perplexing arrangement of the occipital lobe

with the eyes, the temporal lobe's function with

auditory processing makes senses that lie so close

to the ear.

The temporal lobe is also involved in the

comprehension of written and spoken language.

Okay, so let's now give you some clinical

context to what we've just learned.

So one important thing to keep in mind

about the brain is that even though it

has these individual parts that we just learned,

it's constantly working as one cohesive unit, sending

and processing signals between itself and the rest

of the body.

But what happens when a part of this

signaling pathway stops working?

Well, one thing that can cause this is

a stroke, which is when there's a disruption

of blood flow to a region of the

brain, depriving the nerve cells in that area

of nutrients and oxygen.

This can be caused by a blockage or

rupture of a cerebral artery.

The symptoms of a stroke are then dependent

on which region of the brain is afflicted.

If, for example, an artery supplying the parietal

lobe gets blocked, the patient may be present

with a sensory deficit or perhaps may develop

dyslexia or trouble reading, even though they can

clearly see the words.

This symptom is called alexia, and it makes

sense when you consider that the parietal lobe

is one area where language comprehension takes place.

A physician may suspect a stroke based on

physical exam findings, but medical imaging is usually

required to diagnose, like the CT scan that

we see here.

Treatment largely depends on the location and severity

of the stroke, but the primary goal is

to restore blood flow as quickly as possible.

Anticoagulant medications will likely be used to help

break up clots, and if the clot is

large, surgery may be required to remove it.

And just like that, you've now been formally

introduced to the brain.

Let's take a quick look back at what

we learned today.

So we started by looking at the brain's

role within the body as an integral member

of the central nervous system.

We learned how the brain communicates with the

peripheral nervous system by using efferent or motor

nerves to send messages outward, while also receiving

messages via afferent or sensory nerves.

Then we transitioned into identifying the parts of

the actual brain, starting with the brainstem.

We saw that it has three parts, medulla

oblongata, the pons, and the midbrain.

Their functions were also introduced, which primarily included

functions that are essential to life, like regulating

breathing and the sleep cycle, as well as

integration of motor and sensory signals.

We then turned our attention to the posterior

aspect of the brainstem to identify the little

brain, which is the cerebellum.

As we saw, the cerebellum helps us make

fine, balanced, coordinated movements, something that would certainly

come in handy for a gymnast.

As we made our way up the brain,

we were introduced to the diencephalon, or the

interbrain.

And recall that this area has many parts

that help relay signals for sensory information and

autonomic function.

Finally, we reached the functional and positional pinnacle

of the brain, the telencephalon, which we learned

can be divided into hemispheres and further subdivided

into the lobes.

And we then went through and named each

of the lobes being frontal, parietal, occipital, and

temporal.

We then went through each lobe and identified

some of their primary functions.

And to wrap things up, we applied what

we learned in the tutorial to the clinical

scenario of a stroke, which is caused by

a blockage of an artery that supplies the

brain tissue.

And we saw how different symptoms could manifest

depending on which region of the brain was

affected by the blood clot, and diagnostic tools

such as a CT were introduced, and treatment

options such as surgery were discussed.

And that's a wrap for the Basics of

the Brain tutorial.

From all of us here at Kenhub, thanks

for watching and happy studying.