Now, we’re going to transition over to fascial spaces. There are three spaces that can form
between the deep fascial layers. We’re going to be able to see two of these areas very, very well.
The third unfortunately is not well-illustrated in the image but we’ll make note of the fact
that it does exist. First, we have the pretracheal space. The pretracheal space is shown anterior
to the visceral compartment. That’s why it’s anterior to the trachea in this particular view.
A second space is shown right in through here. This is referred to as the retropharyngeal space.
Then it lies between the visceral compartment and its sheath and the vertebral compartment
and its deep fascial layer. The third space is the prevertebral space. That space would be the deep
fascial layer that exists over the anterior portion of the body of related vertebra and
the anterior part of its transverse process. This is a bilaminar area so there’s a space between it.
Unfortunately, it is not well-illustrated in this particular image but it is one to keep in mind.
Why are these fascial spaces important? Well, one area of clinical correlation or relevance here
is that infections and we’ll use the pretracheal space right in through here, if there’s
an infection in this area, it may extend inferiorly and reach the anterior mediastinum.
A second clinical consideration is if invasion occurs, that is invasion of a cancer, the cancer
can spread into any one of these three potential fascial spaces. A third and final consideration
here is with respect to the retropharyngeal space, this space right in through here. If there’s
an infection here, this can spread inferiorly and in fact to the posterior mediastinum
and that could then form an abscess in this particular retropharyngeal space as a result.
Our next area to take a look at is surgical access to the trachea. This may be necessitated
when one cannot intubate and you need to provide ventilation to an unconscious patient
or even a conscious patient. Several approaches, one is a coniotomy. A coniotomy goes
by two alternate names, a cricothyrotomy. This can also be referred to simply as a crike.
Another approach is to perform an upper tracheotomy which will be in this region here.
Then the third approach would be to do a lower tracheotomy shown in this region here.
We will now explore each one of these with the approach taken. Here, I’ll begin with the
coniotomy or simply the crike. The relevant anatomy is the area between the inferior portion
of the thyroid cartilage of the larynx that we see here. This laryngeal cartilage that we see
inferior to the thyroid cartilage is the cricoid cartilage and would be right up here along
its superior border. Running then between these two laryngeal cartilaginous structures
is the cricothyroid membrane. One would get to this level surgically and then horizontal
incision would be performed. Then the patient could be ventilated. This area here
in a coniotomy is immediately inferior to the local cords or folds. The other approach
is the tracheotomy. There’s an upper one and a lower one. Let’s take a look at the upper
tracheotomy first. This is a vertical incision. It is going to run in this area of the anatomy
between the inferior aspect of the cricoid cartilage here and then the isthmus of your
thyroid gland below. Then that will provide surgical access to the trachea in this space.
The lower tracheotomy is going to be inferior to the isthmus of the thyroid gland.
You can see the vertical incision of that approach right in through here.