0:00

So case three, um, is the retromandibular

0:03

trigone extending to the parapharyngeal space.

0:08

So this is a key image, um, and you can see

0:11

that there's a large mass here on the right

0:14

side causing mass effect on the, um, oropharynx.

0:18

So the audience question for you guys to ponder

0:21

while we do the presentation: displacement of

0:23

the parapharyngeal fat medially and posteriorly

0:26

means the primary tumor originates in which space?

0:29

A. Masticator space, B. Parotid space, C. Pharyngeal

0:33

mucosa, D. Carotid space, or E. Um, I don't know.

0:39

So the, um, retromandibular trigone is

0:42

actually part of the oropharynx, however it

0:44

can have extension into the parapharyngeal

0:47

space, which is located in the suprahyoid

0:49

neck, and this is an MR

0:52

image with normal anatomy.

0:54

So the retromandibular trigone in parallel to the

0:59

notorubiae cannot necessarily be palpated by the,

1:03

uh, ENT clinician or the referring clinician.

1:07

Um, it is located in this, uh, little space.

1:09

This is the space of fat here, um, between, uh,

1:12

the, uh, teeth and the body of the mandible.

1:16

Uh, this is the base of the tongue here,

1:18

and these are the masticator muscles.

1:20

And again, it's very important, uh, for us

1:23

to look at this region in our anatomical

1:25

images because if we don't talk about it, uh,

1:28

lesions in this region can, uh, go undiagnosed,

1:31

uh, which causes, uh, poor prognosis.

1:36

So, uh, the retromandibular, uh, trigone again

1:39

is a subsite of the oral cavity, um, which

1:43

consists of the mucosa posterior to the last

1:45

mandibular molar, um, because of its location has

1:49

a propensity to extend into the parapharyngeal

1:52

space, which is part of the suprahyoid neck.

1:55

And like I just mentioned already, if

1:57

you take nothing else of this, of this

1:59

entire presentation today is that the,

2:02

you know, retropharyngeal lymph nodes and

2:04

the retromandibular trigones cannot be

2:06

palpated appropriately by the clinician.

2:09

And if we don't mention it, it is gonna

2:11

go undiagnosed, uh, by the referring

2:14

clinician and of course result in

2:15

much worse prognosis for the patient.

2:20

So, um, again, a brief review of anatomy.

2:23

Again, this is an MR axial image of the neck

2:26

at the level of the, um, retromandibular

2:31

trigone and the parapharyngeal space.

2:34

Um, T2-weighted imaging, which

2:36

we can tell by the bright CSF.

2:38

So masticator space, uh, here in red, um, contains

2:42

the masticator muscles, um, uh, the masseter muscles,

2:45

the pterygoid muscles, and the temporalis muscles.

2:48

Of course, we have the parotid space,

2:50

which contains the parotid gland.

2:52

We have the mucosal space here.

2:55

Again, the longus colli muscle is such an

2:57

important, uh, imaging and anatomical marker for

3:00

us in the head and neck, um, so try to become

3:02

familiar with it. And lateral to the longus

3:04

colli muscle and medial to the masticator space

3:08

is where we have the parapharyngeal space,

3:10

uh, similar to the carotid space. It is, um,

3:13

separated, uh, by the styloid process into

3:17

the pre-styloid parapharyngeal space

3:20

and the post-styloid parapharyngeal space.

3:25

So the contents of the parapharyngeal space

3:27

will be discussed in the next case by Dr. Oldaya.

3:30

72 00:03:31,640 --> 00:03:33,489 It is important to understand what the

3:33

boundaries of the parapharyngeal space are.

3:36

So again, as I mentioned before,

3:38

laterally and

3:40

anteriorly we have the masticator space.

3:44

Laterally and posteriorly we have the

3:46

deep lobe of the parotid gland with

3:48

the retromandibular vein located here.

3:53

Posteriorly we have the styloid process.

3:57

As well as the, uh, tensor veli styloid

4:00

fascia, which is this, uh, white line that,

4:03

uh, we see here, um, and anteriorly we have,

4:07

of course, the, um, uh, the pterygomandibular

4:10

raphe, uh, that extends from the medial, uh,

4:14

pterygoid plate, um, to the mylohyoid line.

4:18

Now, why is it important to understand,

4:20

um, all of these, um, kind of

4:23

boundaries for the parapharyngeal space?

4:25

So similar to the longus colli muscle,

4:28

depending on where the tumor is located, that

4:32

parapharyngeal space fat is going to be displaced.

4:36

So if you have a pharyngeal mucosal lesion,

4:40

which is located anterior and medial to the

4:43

parapharyngeal space, that parapharyngeal fat is

4:46

going to be displaced posteriorly and laterally.

4:49

Okay.

4:50

If you have a masticator, um, space mass, which

4:54

is located anterior and lateral to the parapharyngeal

4:57

space, you're gonna have medial and posterior

5:01

displacement of the parapharyngeal, um, fat.

5:05

If you have a mass in the parotid space,

5:08

which again we mentioned is in the

5:09

lateral and posterior aspect of the

5:12

parapharyngeal space, that's gonna move your

5:15

parapharyngeal fat anteriorly and medially.

5:20

And finally, if you have a carotid space tumor,

5:23

which is located posterior and medial to the

5:27

parapharyngeal fat, that parapharyngeal space is

5:29

going to be displaced anteriorly and laterally.

5:34

Just like the longus colli muscles,

5:36

understanding this anatomical relation between

5:40

the parapharyngeal space and the spaces

5:42

around it, it is critical to understand

5:45

where the epicenter of your lesion is.

5:49

Uh, and I highly encourage you, uh, to

5:51

all to practice, um, locating masses

5:54

by looking at the displacement of the

5:55

parapharyngeal, uh, space fat.

5:59

So audience response now.

6:02

Displacement of the parapharyngeal

6:03

fat medially and posteriorly means

6:06

the tumor originates in which space?

6:11

Okay, great.

6:11

So most of you got the correct

6:13

space, which is the masticator space.

6:15

Perfect.