What's up. Meditay here, and in this video, we're gonna
go through the anatomy of the Pharynx. So in the last video, we went through the
anatomy of the Oral Cavity. Now the step after the oral cavity is the
Pharynx, as you see here. So in this video, we're first going to look
at the parts of the Pharynx. So we're gonna go detailed into the anatomical
structures associated with the Nasopharynx, the Oropharynx, and the Laryngopharynx. After that, we'll cut the Pharynx and look
at the layers of the pharyngeal wall. And then we're gonna go through the muscles
that act on the Pharynx. Now, let's start by holding the Pharynx and
pulling it out. You'll see a kind of look like this as far
as my anatomy program goes, at least. Now the Pharynx is about 12 to 15 cm long,
and it consists of three parts, as you see here. If we look at it anteriorly, you'll see what
the three parts are connected to. The upper one is connected to the nasal cavity;
we call it the Nasopharynx, or Pars nasalis in Latin. The middle part is associated with the oral
cavity, so we call this one the Oropharynx. The lower part is associated with the Larynx,
so we call this Laryngopharynx. Now, let's change the scheme to a lateral
view of the Pharynx to get a better overview. We still have the Nasopharynx, Oropharynx,
and Laryngopharynx here. Now. In terms of the digestive pathway, the Pharynx
will continue downwards as the Oesophagus. You can think of the Pharynx as a control
point for breathing and swallowing, so the Oesophagus is usually closed off when you're
breathing, as you see here. But when you swallow, the soft palate blocks
for the Nasopharynx so the food doesn't end up in your nasal cavity. The Larynx gets blocked by the epiglottis,
and the tongue pushes the food further down by going up to the palate. So that should give you a little overview
of the Pharynx. Let's expand on that now y going through all
structures associated with the Nasopharynx. The Nasopharynx corresponds to the level of
1st to 2nd cervical vertebrae and is attached to the base of the skull. The attachment points between the Pharynx
and the skull base are called Fornix Pharyngis, or translated as the vault of the Pharynx. The vault of Pharynx is where the mucosa,
which is the wet surface in the Pharynx, is firmly attached to specific regions on the
base of the skull. And to understand these attachment points,
let's look at this model right here and look at it from this perspective. And zoom in a little bit. Now we'll be able to see the attachment points
of the Fornix Pharyngis. Now just for orientation sake, here is the
nasal cavity, and here's the oral cavity. SO, this blue line is the attachment points
of the Pharynx, but there are some important landmarks that should be noted when talking
about the Vault of Pharynx, and they're highlighted here. We have the Pharyngeal tubercule of the occipital
bone, which is at the basal part of the occipital bone. The next attachment point is where the occipital
bone and the petrous part of the temporal bone fuse: the Petro-occipital fissures. It also attaches to the inferior border of
the Petrous part of the temporal bone. And it attaches to the medial lamina of the
pterygoid process. So the Pharynx attached to these structures
and forms the vault of Pharynx. Alright, Now the Pharynx and the nasal cavity
are connected, but there's a strict border between those two that you use as a landmark
to separate the Pharynx from the nasal cavity, And this border is called Choanae (or the
internal nose). That's usually the border between the nasal
cavity and the Pharynx. Now another structure you find in the Nasopharynx
is the auditory tube. And that's a tube that connects the middle
ear to the Pharynx. So let's look a little bit into that. SO here you see the eustachian tube or the
auditory tube; it's a synonym. And it's connected to the middle ear. So we have the Outer ear, the middle ear,
and the inner ear. And in the middle ear, that's where you'll
find the ossicles, which are called malleus, incus, and stapes, and this is the tympanic
membrane. So the auditory tube connects the Nasopharynx
to the middle ear. Now, Why do you need the auditory tube? Well, as you're listening to my voice through
this video, your eardrum or tympanic membrane will vibrate in a specific manner. This vibration will then be converted into
words through the whole auditory pathway, based on the vibration of the tympanic membrane. And the tympanic membrane can vibrate because
the pressure difference is stabilized. And you see why it's stabilized; the auditory
tube is the only way the middle ear can regulate its pressure. At rest, the auditory tube is always closed,
completely closed. But remember, in our last video, we looked
at the swallowing process and all the muscles attached to the auditory tube? If you now try to swallow, the auditory tube
opens, and now you'll feel a slight pressure relief in the middle ear. And that's because the auditory tube opens
up to relieve the pressure. When you get in a plane, and you take off,
or as you're landing, and the cabin pressure changes, you can feel that pressure change
in the air, can't you? When you drive up and down mountains and hills,
you feel that pressure change as well. And what you're feeling is the difference
in pressure between the tympanic cavity in here to the air pressure out here. The usual mechanism is that an increase in
pressure in the middle ear will push the tympanic membrane outwards, decrease the pressure,
and the tympanic membrane will be sucked in, as you see here. What can happen is that sometimes, this auditory
tube gets stuck flat due to the pressure change. Now, what do you do to get rid of that sensation? Well, you swallow, you swallow, and then you
feel a slight pop in the ear; that's when you know the eustation tube has opened again
and relieved you from that pressure. So that's one function of the eustachian tube,
equalizing the pressure. Another thing is if you have a middle ear
infection, and a lot of pus starts to build up here. The auditory tube can drain all that pus into
the Pharynx to aid in clearing out that infection. If the infections produce many symptoms, you
can give some broad-spectrum antibiotics to help out as well, like amoxicillin with clavulanic
acid. But we're doing anatomy now, so the two main
functions of the auditory tube are equalizing the pressure when swallowing and draining
the middle ear to protect from pathogens. Alright, so that's the tuba auditiva. The point where the auditory tube opens into
the Pharynx is called ostium pharyngeum tubae auditivae, where ostium means opening in Latin. Here, you'll have cartilage protruding above
the opening of the auditory tube called torus tubarius, or cushion of the auditory canal. As well as a small groove behind the auditory
tube called the pharyngeal recess. Now, we do have tonsils here as well in the
Nasopharynx. There's the pharyngeal tonsil up here, or
also called the adenoids. Which can sometimes be inflamed and enlarged
and block the auditory tube. And another tonsil back here called the tubal
tonsils. And it's called tubal tonsil because it's
behind the auditory tube. So that was all for the anatomy of the Nasopharynx. Next is the Oropharynx, which is situated
at the level of the third/fourth cervical vertebrae. The Oropharynx is bordered by the soft palate
and the epiglottis, as you see here. And It's connected with the Oral cavity through
something called isthmus faucium, or the oropharyngeal isthmus, which is an opening at the back of
the mouth into the throat. Aaand, that is the Oropharynx; not much to
talk about this one. Next, we have the Laryngopharynx, which is
at the level of the 5th to 6th cervical vertebrae. The Laryngopharynx is, as we saw earlier,
going to continue into the Larynx. So whenever you swallow, the epiglottis here
will close the Laryngopharynx so the food can enter the Esophagus and then down to your
stomach instead of down into the lungs. So these two openings are called the laryngeal
inlet and the opening of the Oesophagus. Alright, so if we look at the Larynx posteriorly,
we can see the Nasopharynx up here, Oropharynx here, and then we have the Laryngopharynx
down here. Now there's one more anatomical landmark here
on the Laryngopharynx, called the piriform fossa which is located on either side of the
Laryngopharynx. The piriform fossa is a depression on either
side of the Laryngopharynx. So that was all the parts of the Larynx. Now, let's go through the layers of the pharyngeal
wall. So if you look at the Pharynx again and cut
it right about here, look from this perspective. You'll see that you have four layers. The first one is the tunica mucosa, which
lines the inner layer of the Pharyngeal cavity. The mucosal layer is lined by epithelial tissue,
and different regions are lined by a different type of epithelium. So if we take a small section of the Nasopharynx,
you'll see that it's lined by respiratory epithelium, which consists of pseudostratified
epithelium with cilia, as well as goblet cells between them. While the rest of the Pharynx has to endure
the pressure of food coming through the mouth, so it's lined by stratified squamous non-keratinized
epithelia for protection. So that is the first layer. The next layer is the tela submucosa, containing
primarily Connective Tissue, Blood Vessels and Lymph Vessels, and Glands. So that was this Layer
The next layer Is a muscle layer Called tunica muscularis, consisting mainly of Two types
of muscle fibers. The inner muscle fibers are arranged circularly,
and the outer ones are arranged longitudinally. And here you See Why We Call Them Circular
and longitudinal. You can see that the internal part looks circular
while the outer part looks longitudinal. And that is to aid the pharyngeal peristalsis. Peristalsis is the controlled synchronized
contraction to help with the movement of the content either in or out. So that is this Layer. The last layer is the Tunica Adventitia, which
is a tough layer of collagen fibers that cover the Pharynx from the outside. So that was the pharyngeal wall. The last thing we're gonna look at is the
external muscles of the Pharynx! We divide the muscles of the Pharynx into
the Pharyngeal Constrictors and the Pharyngeal elevators. Both of them Consisting of Three Muscles Each. And you know only by looking at their names
constrictors and elevators, you can kind of already get a hinch of their function. Alright, so let's start with the constrictors
first. So here you see the Pharynx and the skull. And here you see all the three Constrictors
muscles. You have the first one, which is called the
superior pharyngeal constrictor. If we zoom in a little bit, you'll see that
it originates from the pterygoid process, the pterygomandibular raphe. And it's also going to originate from the
mylohyoid line of the mandible. Then it's going to insert at the Pharyngeal
raphe as you see here. The whole white line right here is the Pharyngeal
raphe. So that is this muscle. The next muscle is the Medial pharyngeal constrictor
highlighted right here. It's going to originate from the hyoid bone
and insert at the raphe pharyngis. And the last one is the inferior pharyngeal
constrictor, highlighted right here. This one is pretty interesting because this
one will originate from the thyroid cartilage and the cricoid cartilage; those are the cartilages
of the Larynx, the voicebox. And then, they will insert at the pharyngeal
raphe as well. So the constrictors of the Pharynx are very
easy to remember because they all have the same name. There are the superior medial and inferior
pharyngeal constrictors. They all have the same insertion point, which
is the pharyngeal raphe. And they all have the same function, which
is constricting the Pharynx as you swallow to aid the peristalsis, which is the movement
of the pharyngeal wall to move the content downwards. Alright
So now the next group of muscles is the Pharyngeal Elevators. And remember, the constrictors will constrict
the Pharynx, and the elevators will make sure it elevated the Pharynx when you swallow. The first one is the stylopharyngeus muscle. This one will originate from the styloid process
and insert at the lateral wall of the Pharynx. Again remember, since it originates from up
here and inserts down here, that means when these muscle fibers contract, they're going
to elevate the Pharynx. The next one is the palatopharyngeus muscle. So looking at this name, it originated at
the soft palate and inserts at the Pharynx. Or, to be specific, it originates at the aponeurosis
of the soft palate and inserts at the lateral wall of the Pharynx. And finally, the last muscle of the elevators
is the salpingopharyngeus muscle. It'll originate from the walls of the auditory
tube and insert at the palatopharyngeus muscle fibers. So when you swallow, it's also going to help
open the auditory tube because remember, the auditory tube is closed normally and only
open when you swallow. So that was the anatomy of the Pharynx. The next video is going to be about the Esophagus.