this is Dr Fox let's talk about the pharynx
in this video we'll discuss the pharynx its subdivision and the borders between
those subdivisions and also discuss any of the major contents within those spaces
finally we'll describe how substances May travel among or between these spaces
RX or the throat is a common aerodigestive pathway that links various spaces such as the nasal cavity
the oral cavity the larynx or voice box and the esophagus which is the muscular tube that
leads down to the stomach so we have both food and beverage stuff moving through here saliva
we have air moving between all of these spaces so it's a relatively important space within the body
it's subdivided into three major spaces the nasopharynx the oropharynx and the laryngopharynx
and these spaces are all named for other areas that are contiguous with them anteriorly so let's
have a look at these subdivisions and some of the boundaries between these subdivisions and
other spaces so let's start superiorly start at the top with the nasopharynx in green here the
nasopharynx is located posterior to the nasal cavity which we can see the nasal cavity here
and air moves between the nasal cavity and the nasopharynx through what are known as the choanae
the choanae or singular choana are the internal nostrils or nares so we can see a choana on that
side that's one boundary for the nasopharynx the other boundary is a line drawn from the
soft palate so the palette is the space above the oral cavity there is a hard palate supported
by bones and posteriorly that soft palate extends and we can see that boundary there
um that helps us to divide the nasopharynx from the oropharynx which is below it
that oropharynx is contiguous anteriorly with the oral cavity and we can see the tongue is
one of the major constituents of the oral cavity there um the other boundary for the
oropharynx is the epiglottis which is formed by mucosa going over the epiglottic cartilage along
with the pharyngo-epiglottic fold there so we can establish that as the oropharynx and then finally
the laryngopharynx is the space that is inferior from the oropharynx it's bounded by the laryngeal
Inlet there that's the space through which air is going to move into and out of the larynx and
then the inferior border for the laryngopharynx is the inferior border of the cricoid cartilage
so that cricoid cartilage we can see a little bit of it there and a little bit of it there
that's approximately at the level of the sixth cervical vertebra there so everything inferior
to that border or boundary is the esophagus so that muscularized tube that is heading down to
the stomach let's take a look at some of the contents of these spaces so let's begin with
the nasopharynx superiorly within the nasopharynx so kind of along this surface here we have the
pharyngeal tonsil also known as the adenoids so if you ever have heard of someone having their
adenoid sometimes they say adenoids plural this is incorrect they have that removed that's what
they're they're talking about that pharyngeal tonsil it's a little bit of mucosal-associated
lymphatic tissue along the the superior Edge there and we'll discuss that in Greater detail when we
discuss some of the tonsils and Waldeyer's ring we also have the pharyngotympanic tube
also known as the auditory tube also known as the Eustachian tube and I'll Circle that here
so we can see the opening of it there that is a pathway between the nasopharynx and the middle
ear so if you've ever had that experience of your middle ears popping that's uh that's air
moving through that tube as pressure equilibrates as you change either altitude or depth or enter
into a situation of different pressure sometimes associated with the the margin of that is a little
bit of malt tissue that mucosa-associated lymphoid tissue known as the tubal tonsils
moving uh inferiorly we're going to take two radically different views here one just of
uh the from the anterior including the uh the tongue and another just as a different uh medial
view of this space here is the oropharynx the oropharynx is divided from the oral cavity by
the palatoglossal arch and I'm just going to draw little bits of that Arch there and there those
would connect along the top the palatoglossal arch is formed by the palatoglossal folds the
folds are mucosa that surround little bits of muscle called the palatoglossus muscles
these are muscles that insert into the tongue that really aren't germane here except to say
that they help form these folds that are the boundary between the oral cavity and the or
0 pharynx so behind that palatoglossal Arch there is a palatopharyngeal arch right there and right
there and those two arches are going to delimit a space known as the fauces so here let me draw that
over to there so that's Space Between The Arches is the fauces which is Latin for throat yet again
and the fauces is a large part of the oropharynx which contains some very important structures
so first of all along that lateral wall of the fauces we see Palantine or tonsillar fossa that
contain Palatine tonsils so the Palatine tonsils are the malt tissues that people refer to as the
tonsils so if you ever have your tonsils removed we're talking about those Palatine tonsils there
um and there's more tonsillar tissue here so this is the lingual tonsil this is the root of
the tongue and the surface of the root of the tongue is the lingual tonsil so we have a lot
of lymphatic tissue along the walls and the floor here of the fauces really really fortuitous for us
for as we bring materials in from the oral cavity those materials come in contact with that lymphoid
tissue so as to get the immune system ready are primed for any Bad actors that are entering as
well the other structure of the oropharynx that I want to draw your attention to is the
epiglottic valleculae so the epiglottic valleculae are these little troughs formed by the root of the
tongue and the anterior surface of the epiglottis here and what happens is saliva is conducted down
and then can be stored in those epiglottic valleculae so that it doesn't move into the
rest of the oropharynx to trigger the deglutition or the swallowing reflex so that buys us some time
so that we're not constantly go go swallowing as a result of saliva that comes from our oral cavity
these epiglottic valleculae are a very important anatomical landmark and physical Landmark for
laryngoscopy so that is when we visualize the larynx and here is the inside of the larynx there
what happens is the blade of a Macintosh style laryngoscope inserts there and it can draw the
tongue and subsequently the epiglottis forward so that one may better visualize the larynx and then
finally we have the laryngopharynx and this is a posterior view with the mucosa Stripped Away Let's
uh let's show you some interesting boundaries and contents here so recall that the boundary
between the oropharynx and the laryngopharynx are the pharyngo-epiglottic folds as well as the
epiglottis well here are those folds there end there and here is the epiglottis those
pharyngo-epiglottic folds are formed by mucosa going over a muscle called the stylopharyngeus
muscle the stylopharyngeus muscle is a muscle that we will see in the laboratory as well as
discussed in a subsequent learning objective and that helps to establish that fold which is the
boundary between Oro and the laryngopharynx I'm just going to continue this outlining here so
that we can see the the full structure of the larynx which would be the voice box which is
the proximal portion of the exclusive respiratory pathway so here is the laryngeal Inlet this is the
space by which air is going to enter and leave the larynx and just laterally to the larynx we have
two spaces called the piriform recesses sometimes materials namely dry pills can get stuck in that
piriform recess and it might make you feel as though there's something stuck in your throat
here is the cricoid cartilage and at about the inferior margin of that cricoid cartilage
is the inferior border of the laryngopharynx so anything below that will be within the esophagus
good good so we've discussed the pharynx as an air digestive pathway pointing out many of the
lymphoid structures along the way which comprise wall Dyer's tonsillar ring that's will be the
focus of a subsequent video we've also discussed the nasal Oro and laryngopharynx and their
boundaries as well as some of their major contents this is your summary slide thank you for your time