hi let's talk about the fascia associated with the pharynx and the retro pharyngeal space in this video
we'll talk about the various fascia associated with the pharynx and we'll describe the boundaries and
divisions of the retro pharyngeal space and discuss any clinical correlations so we're
looking here at a transverse section of the neck here is anterior here is posterior we can see
from the orientation of this particular cervical vertebra the various neck muscles and viscera and
compartments within the neck so just to give us some further orientation of viscera etc there's
our trachea there is our esophagus and we can see the thyroid gland wrapped about there here
are some of those infrahyoid muscles there's SCM on either side and then there's trapezius and then
wrapping around here are the carotid sheaths so in other videos there was a discussion of
the various layers of the cervical fascia etc and I really want us to focus here on some of
the particulars of the deep cervical fascia and we'll we'll call in to play some of the middle
layers of the deep cervical fascia as well as the deep layers of the deep cervical fascia
so that that we can begin to to understand the particulars of the facial spaces that they are
now fossil spaces generally not always but generally our potential spaces so they're layered
upon one another and other features and from time to time infections can spread various tissues can
metastasize into these spaces anesthetic agents when injected into a potential space can spread
even air as we can see can can move in a potential space and I've even published on on this so - to
get to the the particulars of what I'd like to discuss so this blue layer here is a light
blue layer just outline it this is the bucco pharyngeal fascia that buccopharyngeal
fascia is going to be found on the posterior aspect here of the esophagus and it it's going
to be the the investing fascia of the posterior and lateral walls of the pharyngeal constrictor
muscles as we'll see shortly posterior to this buccopharyngeal fascia we have some of the deep
layers of the deep cervical fascia we have these alar fascia that's this light green layer here this
alar fascia is running between the the transverse processes of the of the vertebrate specifically
the cervical vertebrae and then we have the pre vertebral fascia and this pre vertebral flashes is
much more extensive surrounding the the vertebrae throughout the neck but I want us to focus on just
this anterior portion of it and we can see that the prevertebral fascia is investing around not
just the vertebral column but also the the deep muscles of the neck as well now thanks to all of
these facial layers we have some facial spaces in here than going to erase some of this so is not to
distract from these fascial spaces the the first fascial space that that I'd like to point out is
going to be between the buccopharyngeal fascia and the a large washes so just maybe that space there
and we refer to that space as the true retropharyngeal space the the true retropharyngeal space
is sandwiched between the bucopharyngeal fascia and the alar fascia and it's called the true retropharyngeal space because it is immediately retro or behind the pharynx if we go on the other side
of the a la faccia so sandwiched between the alar fascia and the pre vertebral fascia here we
have the danger space that that danger space combined with the true retro pharyngeal space
so these two together are going to comprise the retropharyngeal space that's a little confusing
but we've got two fascial spaces that that come together to form the retro pharyngeal
space and I think that this will look a little better when we see this in a sagittal section
so here is our cutout here and we can make that a little bigger over here so we will ambiguous
so anteriorly here is the buccopharyngeal fossa coming down and then the
alar fascia is behind that but between the two is that true retro pharyngeal space
behind the alar fascia is the danger space and then the posterior border of that danger space
is the pre vertebral facha as it comes so up here I've kind of made this even greater of a cartoon
so here is the bucopharyngeal fossa that bucopharyngeal fascia posterior and the lateral
or I should say the more superficial aspects of the pharyngeal constrictor muscles and you know
superior pharyngeal constrictor muscle you know in that area but as we move down we'll get into
the middle for initial constrictor muscle behind that is our true retropharyngeal space and the the
boundary for the true retro pharyngeal space and the danger space is the alar fascia that alar
fascia is is kind of unique it goes up to nearly the base of the skull so up to the the first
cervical vertebra up to the Atlas and at about the level of c6 but this is highly variable can even
go down to t4 that a la faccia is going to combine with the bucopharyngeal fascia so what happens
here is that true retropharyngeal space is more of a pocket and so there's a there's a barrier
or an impedance to the movement of any materials that enter that space inferiorly whereas if we go
posterior to the alar fascia we're in the danger space so between the alar fascia in the pre vertebral fascia that that danger space is completely contiguous from posterior here all the way down
into the the superior mediastinum of the thorax and so this is a theoretical route through which
infection can spread metastasis may spread between the the neck and the the retro pharyngeal area
down into the thorax now I want to to discuss ever so briefly the the lateral pharyngeal space in its
relationship to the the retropharyngeal space and so over here we can see this is our superior
pharyngeal constrictor and our middle foreign jewel constrictor so we know that the the retropharyngeal space is going to be behind this well there's also a lateral pharyngeal space
and the lateral pharyngeal conceptualized kind of like an inverted pyramid so the base of the
pyramid is up here and it comes down to about the hyoid region and it's not a perfect pyramid but
coming up and this would be the lateral pharyngeal lateral pharyngeal space is contiguous with
the retropharyngeal space so here's the stylohyoid ligament coming down that way and so
there's an anterior portion to it and a posterior portion to it and this lateral pharyngeal space is
contiguous with other facial spaces in particular there's a sub masseteric space sometimes just
called the masseteric space by clinicians and there's also a pterygomandibular space it's
really difficult to to get a sense for depth here but I'll just roughly talk through this for those
of you that that care for it for those who don't you know you can you can fast-forward through this
but if you can imagine you know coming down here onto the the mandible would would be our
masseter right that masseter is a robust muscle of mastication it's very lateral very superficial and
then deep to that masseter is the ramus of the mandible but between the ramus of the mandible
and the masseter so this would be the superficial masseter and then here is our ramus of mandible
so between the masseter and the ramus is that sub masseteric space deep to
the ramus of the mandible is our pterygomandibular space and that
pterygomandibular space is going to be bounded by the medial pterygoid muscle
so we'll we'll learn in the in the muscles of mastication session that the the mandible is
really in a muscular swing with the masseter superficial and the medial pterygoid deep and
so flanking the ramus are going to be these two facial spaces the sub masseteric space in
the pterygomandibular space these spaces are going to be contiguous anteriorly with the
buccal space and just clean this out a little that buccal space is going to be superficial to
the Bucccinator here we can see there's that pterygomandibular raphe with the Buccinator
muscle that is anterior to it in the superior pharyngeal constrictor muscle posterior to it
and so we can have the movement of materials from you know the the face in for orbital space buccal
space posteriorly back into these sub masseteric and pterygomandibular spaces which are contiguous
with the lateral pharyngeal which is contiguous with the retro pharyngeal space so this is a
this is a pathway through which materials may move which leads us to the assessment question
an infection originating from a periapical abscess of a mandibular second molar could theoretically
travel to the thorax via which conduit would it be the danger space the true retropharyngeal
space or the retro pharyngeal space well let's think about this both a and B together so
danger space plus the true retro pharyngeal space equals the retro pharyngeal space so a
plus B equals C so C is going to be too general and answer the the danger space versus the true
retropharyngeal space let's think about that here so here's our buccopharyngeal fossa there is our
alar fascia and there is our prevertebral fascia so between buccopharyngeal and alar is going to be the
true retropharyngeal space posterior to alar will be the danger space and this true retropharyngeal
space if you recall somewhere around c6 all the way down to t4 blends with the buccopharyngeal fascia
to create a pocket so the the potential conduit from the retro pharyngeal space is going to be the
danger space and I guess that's probably good that they called it the danger space because that would
be a dangerous pathway so our correct answer is a the danger space thank you very much for your time