2:00

So when we talk about the anatomy of the brachial plexus,

2:03

it's really divided into,

2:06

the classic anatomy that we learned in medical school,

2:08

is roots, trunks, divisions, cords and branches.

2:11

And I have to admit, my son just started medical school.

2:13

I don't know if he's listening or not,

2:14

probably not, but he just started medical school.

2:17

So he was texting me

2:18

actually, on the anatomy of the brachial plexus.

2:20

So for me, it was a nice revision to understand

2:23

the people are currently learning this as well in

2:26

medical school, but it really just emphasizes that one of

2:28

the key principles in head, neck radiology

2:30

is actually the anatomy. Because if you don't understand

2:33

the anatomy, especially when it comes

2:34

to the brachial plexus,

2:36

honestly,

2:36

you're going to be lost when you're trying to

2:37

interpret these,

2:38

these,

2:39

these studies.

2:40

So the classical anatomy that we learn was roots,

2:43

trunks, divisions, cords and branches.

2:47

And then, I have a hard time remembering but I do sort of

2:50

like to look at the mnemonics,

2:51

and the mnemonics that I like to

2:54

use for the brachial plexus are that 'Radiology Tech's Drink

2:58

Cold Beer', and you can separate Beer with beverages

3:00

if you want. I don't need to be politically correct on this,

3:03

obviously. But if you just remember,

3:06

excuse me,

3:06

that the R stands for radiology,

3:07

the T stands for techs, the D stands for drinks,

3:11

the C stands for the cold and the beer. So it's roots,

3:14

trunks, divisions, cords,

3:16

and the branches, you'll always be able to remember

3:19

the anatomy of the brachial plexus.

3:22

So when we look at the components of the brachial

3:25

plexus, as mentioned before, it runs from C5 through T1.

3:29

Now, C5 and C6, if you look at the schematic on the left,

3:33

combine to form the upper trunk,

3:35

C7 kind of runs by itself and then C8 and T1 combined

3:40

to form the lower trunk of the brachial plexus.

3:45

Then what happens is that the trunks end up dividing.

3:48

So here, we have the schematic illustrations of some

3:50

of the trunks and also in cyan as well too.

3:53

And then the trunks end up dividing, and the reason they

3:57

divide is to form the cords of the brachial plexus.

4:00

And the cords of the brachial plexus are identified

4:02

and named by the relationship with the subclavian artery.

4:07

So subclavian / axillary artery is demarcated here

4:11

by this red triangle.

4:13

So we have a cord that's posterior to the subclavian

4:17

artery which is a posterior cord.

4:18

We have one that's lateral to the subclavian artery,

4:21

and then we have one that's medial

4:23

to the subclavian artery.

4:24

So that's our roots, trunks, divisions, cords,

4:27

and eventually the branches.

4:28

We won't be talking too much about the branches because

4:31

that's really more appropriate for musculoskeletal talk.

4:35

So then what happens is that we end

4:37

up having the surgical anatomy.

4:41

So, the surgical anatomy is based on the relationship

4:43

with the clavicle.

4:44

So we have the clavicle, which is located here,

4:47

and the surgeons divide up the brachial plexus

4:49

into a supraclavicular portion of brachial plexus.

4:52

A retro clavicular portion of the brachial plexus and

4:55

an infra clavicular portion of the brachial plexus.

4:58

So when you look at this diagram,

5:00

the supraclavicular portion,

5:01

the surgical anatomy is comprised of the roots

5:05

and some of the spinal nerves and the trunk.

5:07

So this is what we just talked about

5:08

before in the classical anatomy.

5:11

Then we have an area that's behind the clavicle,

5:14

which is the divisions of the brachial plexus.

5:17

And then we have those components of the brachial

5:19

plexus that are below the clavicle, and those are the

5:22

cords and the nerves of the brachial plexus.

5:24

So again, we won't spend too much time talking about the

5:27

nerves, maybe just really briefly at the end.

5:29

But predominantly, we're going to be focused

5:31

on the cords of the brachial plexus.

5:33

So the supraclavicular plexus,

5:36

the retroclavicular plexus and the infraclavicular plexus

5:40

form the surgical anatomy of the brachial plexus.

5:43

So we've talked about the radiological anatomy,

5:46

we talked about the surgical anatomy, and now what we'll

5:49

do is what I refer to, is that we'll talk about the

5:51

radiological anatomy.

5:53

I should have said the classical anatomy,

5:54

not the radiological anatomy.

5:55

Now, we'll talk about the radiological anatomy.

5:58

So the radiological anatomy that we need to look for

6:02

is to look for these two muscles which is the anterior

6:05

and the middle scalene muscle.

6:06

So when we look at the schematic illustration,

6:08

we can put all of that anatomy together.

6:12

So this muscle is the anterior scalene muscle

6:14

and the muscle more posteriorly is combined in part

6:17

by the middle scalene and the posterior scaling,

6:20

depend on where you are in the neck.

6:22

Now, between the anterior and the middle scalene muscles,

6:25

we can now see that classical anatomy, if you will,

6:28

and these are the roots and then which form the trunks.

6:31

So remember, the surgical anatomy also talked

6:34

about that supraclavicular plexus.

6:35

So really it combines all three of those classifications

6:40

of the anatomy.

6:42

So when we look at the radiological anatomy,

6:45

you know, I know the neck can be a little bit complicated.

6:48

So on the left here is a schematic or scoot...

6:51

you should see an anatomic diagram of the neck

6:53

from the visible human project.

6:54

And this is just a standard axial T1-weighted image.