0:01

The carotid space is defined by the various

0:05

layers of the deep cervical fascia,

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which some people refer to as superficial,

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middle, and deep layers of the deep cervical fascia.

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However,

0:15

in this diagram, we're better able to see the

0:18

components that make up the carotid sheath.

0:21

Structures in the green here, we see what is

0:26

enclosing the visceral space, and that is

0:31

called the pretracheal visceral fascia.

0:35

That pretracheal visceral fascia is part of the

0:40

carotid sheath and is considered the middle

0:46

layer of the deep cervical fascia.

0:48

The anterior part of the carotid sheath is made up,

0:53

as you can see, by this purplish-red magenta tissue,

0:58

and that is the superficial or investing

1:02

layer of the deep cervical fascia.

1:05

These two areas can be seen on this magnified

1:07

view over here of the carotid.

1:10

So this is the investing or superficial

1:14

portion of the deep cervical fascia.

1:17

The final component of the deep cervical fascia that

1:20

contributes to the carotid is that which is

1:22

considered the prevertebral layer or the

1:25

deep layer of the deep cervical fascia.

1:30

This is seen along the posterior

1:32

margin of the carotid sheath,

1:36

shown here merging with the prevertebral space.

1:42

So these are the three components:

1:45

the superficial investing layer,

1:48

the middle pretracheal layer, and

1:52

the deep prevertebral layer.

1:54

Also seen on this diagram is the vagus nerve,

1:59

which you will see is between the carotid artery and

2:02

the jugular vein, and therefore, pathology tends to

2:05

push the carotid artery anteriormedially and displace

2:10

the jugular vein laterally and

2:13

predominantly posteriorly.

2:15

You also see something that is layered on the

2:17

diagram right here as the phrenic nerve.

2:21

This is actually not the phrenic nerve.

2:23

This is part of the sympathetic nervous system

2:26

plexus, and the sympathetic nervous system plexus is

2:29

also enclosed within the carotid sheath, and it tends

2:33

to push both the jugular vein as well

2:35

as the carotid artery anteriorly.

2:38

I hope this helps one to understand the

2:43

components of the carotid sheath.