Interactive Transcript
0:01
Hello everyone.
0:02
It's Dr. Sidney Levy here.
0:05
Today I'd like to discuss Level 3 of
0:08
the lymph node levels of the neck.
0:10
This is the middle internal jugular or deep cervical chain.
0:14
I would like to use pre-contrast T1-weighted imaging to
0:19
demonstrate its boundaries and to show you key landmarks
0:23
to help you identify Level 3 and distinguish it from
0:28
Level 2, Level 4, and Level 5, which surround it.
0:32
So, Level 3, first thing to remember is that it is
0:35
situated inferior to Level 2 and superior to Level 4,
0:41
and it is situated anterior and medial to Level 5.
0:47
The key landmarks to consider are in the supero-inferior
0:53
plane, the hyoid bone and the cricoid cartilage.
0:58
So let me start off by demonstrating those for you.
1:01
It's easiest to see in the sagittal plane.
1:04
This is the hyoid bone here.
1:06
One way you can easily tell is that there are extrinsic
1:09
tongue muscles, such as geniohyoid, which attach to it.
1:13
You can always cross-correlate with the axial projection.
1:17
The next structure you need to be
1:18
aware of is the cricoid cartilage.
1:21
The cricoid cartilage actually sits here.
1:24
And we are interested in the inferior margin of the
1:27
cricoid cartilage as well as the inferior margin
1:31
of the hyoid bone.
1:32
Anything between those two boundaries is within Level 3.
1:38
The other boundary you need to consider is
1:42
the boundary between Level 5 and Level 3.
1:46
And this is formed by the posterior
1:49
border of sternocleidomastoid.
1:52
So anything that is posterior or lateral to the
1:58
posterior margin of sternocleidomastoid, so that's here,
2:03
is within Level 5, whereas anything medial or anterior
2:09
to the posterior border of sternocleidomastoid is within
2:13
Level 3, remembering the superior and inferior boundaries.
2:17
Now that's almost it.
2:20
There is one other landmark you need to be aware
2:23
of, particularly more inferiorly, and that is
2:29
the boundary between Level 3 and Level 6.
2:35
So Level 6 comes into play in the vicinity of
2:39
the laryngeal cartilages and the thyroid gland.
2:43
It is the anterior compartment, and Level 3
2:48
lies lateral to it, and what you need to remember
2:53
for that is the internal carotid or common carotid
2:58
artery and, in particular, the medial margin.
3:02
So anything medial to the medial margin of the internal
3:09
carotid artery is going to be within Level 6 anteriorly.
3:16
The last thing I'd like to do is to just put all
3:19
of that together and draw Level 3 for you at
3:23
a given plane, just to give you some orientation.
3:27
So if we have the hyoid here,
3:29
we have the cricoid here, let's peek
3:32
halfway in between, let's find a good
3:35
image of the carotid artery, just there.
3:39
In this case, it'll be the common carotid artery.
3:43
And we just need to remember that we are
3:47
between the inferior border of the cricoid
3:50
cartilage and the inferior border of the hyoid.
3:54
We are lateral to the medial margin
3:58
of the internal carotid artery.
4:00
And we are anterior and medial to the
4:02
posterior border of sternocleidomastoid.
4:06
So if we remember all of that, we find ourselves in
4:10
Level 3 here, with Level 5 out here, Level 6 in here,
4:19
Levels 2A, 1B, and 2B there, and Level 4 below.
4:27
In our next vignette, we will discuss Level 4.
© 2024 Medality. All Rights Reserved.