0:01

Hello, everyone, Dr. Sydney Levy here today. I

0:04

would like to discuss the anatomy of

0:07

the larynx as a Prelude to

0:10

the diagnosis and staging of

0:13

laryngeal squamous cell carcinoma.

0:16

I would like to begin by drawing and describing

0:19

the boundaries of the larynx and

0:22

its relationship to adjacent subsides within

0:25

the head and neck.

0:27

I have a sample pre contrast T1

0:30

weighted series, which actually

0:33

does demonstrate a post-cricoid tumor

0:37

here, but

0:39

This doesn't involve the larynx at the

0:42

level that we're interested in. So it will serve as a

0:45

good example case to show us laryngeal Anatomy.

0:49

I'm going to begin by drawing the boundaries of

0:52

the larynx firstly.

0:55

What is the superior boundary?

0:57

It is the junction of the laryngeal service

1:00

of the epiglottis.

1:03

and

1:05

the area epiglottic Folds

1:08

this is the laryngeal surface of the ebiglottis which

1:11

belongs to the larynx. So everything

1:14

about this level belongs to the

1:17

oropharynx.

1:20

The inferior boundary of the larynx is

1:23

the inferior border of the cricoid cartilage.

1:28

This is the cricoid cartilage.

1:32

Therefore everything between these levels

1:35

anteriorly belongs in the larynx.

1:39

We have the laryngeal Inlet here.

1:42

Which is a space.

1:44

posterior to which we have the hypopharynx

1:48

Which then extends?

1:50

Inferiorly posterior to

1:53

the supraglottis the glottis and the sub-lottis of

1:56

the larynx and consists of

1:59

the post-cricoid space anteriorly and

2:03

the posterior hypopharyngeal wall

2:06

posteriorly.

2:08

and lastly

2:10

we have the anterior wall.

2:12

of the larynx

2:14

or more specifically the laryngeal mucosa.

2:18

Now I'm just going to draw those other compartments for

2:21

you.

2:23

So we've already mentioned oropharynx.

2:26

here

2:27

we have hypopharynx.

2:31

and inferiorly

2:32

There's trachea.

2:34

cervical trachea

2:35

so

2:37

what are the structures do we need to be familiar with in the

2:40

larynx? There are many.

2:42

But there are certain core structures

2:45

which you need to be able to identify.

2:48

And a good place to start is the laryngeal cartilages.

2:53

And for this I have selected the

2:56

axial projection and drawn the retinoid cartilages.

3:01

here

3:03

and the thyroid cartilage

3:05

and this is at the level of the glottis.

3:09

So we have the anterior commissure.

3:13

here

3:15

and the posterior commissure here.

3:18

We are just beginning to see the

3:22

top of the cricoid cartilage here.

3:25

It is easier to appreciate on the

3:28

coronal projection a little lower.

3:31

So we're strictly still in soft tissue here, but

3:34

we're very close to the top of the cricoid cartilage

3:38

and if we just go down one more slice.

3:41

You can see the cricoid cartilage quite clearly.

3:45

So you need to be able to identify the laryngeal cartilages?

3:49

This is at the level of the glottis.

3:52

the glottis extends for a distance of

3:56

approximately one centimeter in a super-inferior

3:59

dimension

4:01

and is one of the key subtites of

4:04

the larynx where the vocal cords reside above the

4:07

glottis. We have the laryngeal ventricles.

4:11

Draw them for you.

4:13

These are the laryngeal ventricles.

4:16

These are the vocal cords of the glottis and

4:19

this below is the

4:22

subglottis.

4:24

Which extends as far as the

4:27

inferior margin of the

4:30

cricoid cartilage, so all this region here?

4:34

belongs to the sub-blottis

4:36

whereas this centimeter also.

4:40

Centered around the anterior and posterior commissures constitutes

4:43

the glottis.

4:46

And then Superior to this level.

4:49

involving the

4:51

laryngeal ventricles and the false

4:54

chords and the area epiglottic

4:57

Folds

4:59

we have the super glottis.

5:01

on the axial projection

5:04

I will take you up to the level of the area

5:07

epiglottic folds as I'm scrolling. This

5:10

is the epiglottis here and these

5:13

are

5:15

The area epiglottic faults, the area puglotic

5:18

folds are very important because they are the

5:21

boundary between the super-glottis of

5:24

the larynx and the hypopharynx more

5:27

specifically the piriform Fossey.

5:30

this region here

5:32

Is the supraglottic larynx, this is

5:35

the laryngeal Inlet.

5:37

This is the medial wall.

5:40

Or laryngeal wall of the area epiglottic faults

5:43

the lateral wall of the area of

5:46

epiglottic folds belongs to the piriform sinus

5:49

which are here.

5:52

so this

5:54

is all hypopharynx. Where is this?

5:58

is superglottic larynx, so that's

6:01

an important distinction to be able to make

6:04

as we head down into the supraglottis the

6:07

next set of structures. We will look for are the

6:10

false chords the false chords.

6:13

Are well seen on this coronal projection?

6:16

They are situated here.

6:19

and then just underneath

6:21

we have the laryngeal ventricles.

6:23

at the level of the false chords, there are

6:26

normal fat planes separating the

6:29

thyroid cartilage from the

6:34

false chords. This is known as the paraglonic fat

6:37

and it is in important structure to be

6:40

familiar with as it can be effaced by tumor.

6:43

So you want to be able to identify these?

6:47

As we keep heading further down.

6:49

You will reach the retinoid cartilages and

6:52

this is now at the level of the

6:55

glottis where the vocal cords are

6:58

reciting and which do attach

7:01

to the retinoid cartilages. The vocal

7:04

chords are here.

7:06

The eretinoid cartilages are here.

7:09

And this is the thyroid cartilage surrounding it all one other

7:12

region. That's both being aware of is a little bit further

7:15

up when I mentioned the paraglottic fat. It is

7:18

also worth being aware of the pre epiglotic

7:21

space here as this can also be effaced by

7:24

tumor. So that's another structure that's worth being

7:27

familiar with paraglottic fat here pre

7:30

epiglottic fat or space anteriorly.

7:34

And lastly once we've gone beyond

7:37

the level of the vocal cords, we are into the

7:40

sub-glottis.

7:41

And it is most easily recognized by

7:44

the presence of the cricoid cartilage, which is

7:47

here.

7:49

And if you keep going further down.

7:52

The inferior border of the subglottis is the inferior

7:55

border of the cricoid cartilage. So in

7:58

summary, there's a lot of information there, but

8:02

there are three sub sites of the larynx.

8:06

the super glottis glottis and sub-glottis

8:10

and it's important to understand the boundaries of

8:13

the larynx as well as the key structures

8:16

within the larynx that can be compromised by

8:19

tumor in this area.