Description

Borders of the Oral Cavity Proper:

• Anterior and Lateral Border: Teeth, Gums
• Superior Border: Hard Palate, Soft Palate
• Inferior Border: Mylohyoid, Digastric, Geniohyoid Muscles, Tongue
• Posterior Border: Oropharyngeal Isthmus

Superior Border:

• Hard Palate (Palatum Durum)
  • Anterior Part: Alveolar Processes of Maxilla
  • Posterior Part: Horizontal Plate of Palatine Bone
  • Covered by Periosteum
  • Covered by Mucous Membrane containing Palatine Glands
  • Key Structures:
    • Incisive Papilla
    • Palatine Raphe
    • Transverse Palatine Folds
• Soft Palate (Palatum Molle)
  • Velum Palatinum – Free part of the posterior palate
  • Contains muscle tissue, palatine aponeurosis, vasculature, and mucous glands
  • Key Structure: Uvula (Uvula Palatina)

Swallowing Process:

1. Tongue Blocks the Oral Cavity
2. Soft Palate Blocks the Nasal Cavity
3. Epiglottis Blocks the Larynx

Muscles of the Soft Palate:

• Muscle of the Uvula (Musculus Uvulae)
• Levator Veli Palatini (Musculus Levator Veli Palatini)
• Tensor Veli Palatini (Musculus Tensor Veli Palatini)
• Palatoglossus Muscle (Musculus Palatoglossus)
• Palatopharyngeus Muscle (Musculus Palatopharyngeus)

Structures Formed by the Palatoglossal and Palatopharyngeal Muscles:

• Palatoglossal Arch (Arcus Palatoglossus)
• Palatopharyngeal Arch (Arcus Palatopharyngeus)
• Palatine Tonsil (Tonsilla Palatina)

Inferior Border: Floor of the Oral Cavity

• Mylohyoid Muscle
• Anterior Belly of Digastric Muscle
• Geniohyoid Muscle

Structures of the Tongue:

• Muscle organ composed of several muscles
• Divided into 3 parts: Apex, Body, and Root of Tongue
• Key Features:
  • Medial Sulcus (Sulcus Medianus)
  • Terminal Sulcus (Sulcus Terminalis)
  • Foramen Caecum of the Tongue (Foramen Linguae)
  • Lingual Tonsil (Tonsilla Lingualis)
  • Glossoepiglottic Folds:
    • Right/Left Glossoepiglottic Folds (Plica Glossoepiglottica Dextra et Sinistra)
    • Median Glossoepiglottic Fold (Plica Glossoepiglottica Mediana)
  • Epiglottic Vallecula (Valleculae Epiglotticae)
  • Frenulum of the Tongue (Frenulum Linguae)
  • Fimbriated Folds (Plica Fimbriata)
  • Sublingual Folds (Plica Sublingualis)
  • Sublingual Caruncle (Caruncula Sublingualis)

Muscles of the Tongue:

• Extrinsic (Extraglossal) Muscles:
  • Genioglossus Muscle (Musculus Genioglossus)
  • Styloglossus Muscle (Musculus Styloglossus)
  • Hyoglossus Muscle (Musculus Hyoglossus)
  • Palatoglossus Muscle (Musculus Palatoglossus)
• Intrinsic (Intraglossal) Muscles:
  • Superior and Inferior Longitudinal Muscles
  • Vertical Muscles of the Tongue
  • Transverse Muscles of the Tongue

Lingual Papillae:

• Filiform Papilla
• Fungiform Papilla
• Vallate Papilla
• Foliate Papilla

Posterior Border:

• Oropharynx
• Isthmus of Fauces (Isthmus Faucium)

Sources:

• Memorix Anatomy, 2nd Edition by Hudák Radovan, Kachlík David, and Volný Ondřej.
• Biorender
• University Notes and Lectures

Transcript

Introduction
0:00
What’s up, Meditay here. Let’s talk about the digestive system anatomy. In our last video,
0:01
we covered the anatomical structures associated with the Oral Vestibule. Which remember consists
0:06
of the external borders with the Lips and Cheeks, and the Inter borders with the Teeth and Gums.
0:12
Now let’s wrap up the anatomy of the oral cavity, by going through the anatomical structures
0:17
associated with the Oral Cavity Proper. And to do that, we need to go through the
0:21
borders of the oral cavity proper. First, we have the Anterior and Lateral border,
0:27
which are the alveolar processes and the gums, as well as the teeth, we already covered them
Borders of the Oral Cavity Proper
0:31
in the last video, since the teeth and gums are also the internal borders of the oral vestibule.
0:36
Superiorly however, you’ll find the hard palate, and the soft palate.
0:40
The inferior border consist of the floor of the oral cavity, which is made up by
0:45
the mylohyoid muscle, anterior belly of digastric muscle and the geniohyoid muscle. And you’ll find
0:51
the tongue here in the inferior border. Posteriorly, the oral cavity proper will
0:56
continue into the pharynx through the oropharyngeal isthmus.
1:00
So our goal in this video is to go through all the structures associated with these borders here.
1:06
We talked through the anterior and lateral border in our last video. Now, let’s start with the
1:11
superior border, which consists of the Palate. The palate is kind of a horizontal partition
Superior Border: Palate
1:18
separating the oral cavity from the nasal cavity. The ventral part is formed by the
1:23
bony hard palate. It’s hard because it primarily contains bone. The dorsal part is called the soft
1:30
palate and is formed primarily by tendons. The palate is used primarily during swallowing,
1:38
and I’ll show you how in a minute. But let’s start with the hard palate first.
1:42
The anterior part of the hard palate consists of the alveolar processes of the maxilla,
Hard Palate
1:48
and the posterior part is made up of the horizontal plate of the palate bone
1:52
Now the hard palate is bone. And just like the rest of the body. All bones are usually
1:58
covered by periosteum, as you see here. And externally to the periosteum, you’ll
2:04
find the mucus membrane, which contain minor salivary glands called palatine glands, that
2:11
continuously produces a minor amount of saliva to keep the inner environment of the mouth wet.
2:17
When you look at the hard palate, there are some distinct structures you can highlight here. First,
2:22
we have the incisive papilla, which is a small elevation on the mucosa that lies on top of the
2:28
incisive canal. You can feel it as a very small elevation here in this region. In the midline,
2:34
we can see the palatine raphe, which is a ridge running in the middle here. And then there’s the
2:40
transverse palatine folds, which are transverse mucosal folds on the oral side of the palate.
2:46
So that’s everything for the anatomy of the hard palate. Now let’s go through the soft palate.
Soft Palate
2:50
Now the soft palate again is this posterior flappy part that doesn’t contain any bone.
2:56
In Latin, you’ll sometimes see the soft palate being referred to as Velum Palatinum,
3:02
as described as the free part on the backside of the palate, but essentially when we talk
3:07
about velum palatinum, we generally mean the middle part of he soft palate.
3:11
But the posterior end of the soft palate is a free, it’s called the uvula.
3:16
It’s the thing dangling around on the backside of your mouth here.
3:19
Now. What makes up the soft palate? First, I want you to imagine that you have a
3:24
bag. And this bag is made up of a mucosal membrane. And within the bag,
3:30
you’ll find muscles, or muscle tissue. You’ll also find a lot of fibers that clump together
3:37
and form a structure called the Palatine Aponeurosis. And this palatine aponeurosis
3:43
functions as an attachment point for many of the muscles related with the soft plate.
3:48
Other things you’ll find within this bag are vasculature. You know arteries, veins,
3:52
nerves and lymph tissue, all of them go under this category. You’ll also find mucous glands,
3:58
or palatine glands, similar to the hard palate. And so this bag that we just imagined, resembles
4:04
the soft palate and all structures associated with it. Awesome. So why do we have the soft palate,
4:10
and why is it so important? Well first thing is that
4:13
it’s involved in the swallowing process. So, imagine you’re about to take a large
Swallowing Process
4:17
bite of this hamburger. But you’re so hungry you just end up eating the whole thing in one go.
4:22
And when you’re ready to swallow it. There are actually 4 directions it can go through.
4:26
One thing is that it can go up to your nasal cavity through the nasal part of the pharynx.
4:31
Or it can get pushed back into the mouth, or it can go down through your larynx and the trachea
4:38
and into the lungs. Or it can go through the esophagus and then further down into the stomach.
4:44
The esophagus is where we wanna push the food, so the actual swallowing process involves cutting off
4:50
the other three pathways. So the three steps in swallowing involved the tongue blocking the oral
4:56
cavity. The soft palate blocking for the nasal cavity, and then the epiglottis, going down and
5:02
blocking the larynx. Now we only have one pathway left, which is through the esophagus. And here to
5:09
further help you imagine it through an X-ray. This is a person swallowing water. Did you catch that?
5:15
Here in slow motion, you’ll see the tongue going up. The soft palate blocking for the nasopharynx,
5:22
and the epiglottis blocking the Larynx. So that’s the main function of the soft palate.
5:27
The other thing you need to know about it, is that it serves as an attachment point for 5 different
Muscles of the Soft Palate
5:33
muscles. So let’s go through these muscles. And to do that, we’re first going to make a vertical cut
5:38
like this. And remove the backside. And then look from this perspective, we’ll see this.
5:44
SO we can see the Sphenoid bone. We can see the nasal cavity, with the septum here in the middle.
5:50
We can see the tongue, we cans se the uvula, and we can see the horizontal plate of the palate
5:55
bone. Awesome. So let’s use this model to go through the 5 muscles attaches to the soft palate.
6:01
The first muscle si the muscle of the Uvula, which is this one.
6:05
It originates from the palate bone, as you see here. And inserts at the mucous
6:10
membrane of the Uvula. And its function is to shorten and elevate the uvula.
6:15
Then we have a muscle called the Levator Veli Palatini. Which is this one. This
6:20
muscle originates from the petrous part of the temporal bone, as well as from the auditory
6:25
tube. And it inserts at the Palatine Aponeurosis. And its function is to elevate the soft palate.
6:31
Notice that the auditory tube is involved. So, when you swallow, it’s going to open up the
6:37
auditory tube to a certain extent and release some pressure off the middle ear. So, levator,
6:43
elevates the soft palate. Then we have the Tensor veli palatini, which tenses the soft palate.
6:49
It looks like this, and it originates from the spine of the sphenoid bone.
6:54
From the medial lamina of the pterygoid bone, as well as from the auditory tube.
6:59
And it inserts at the palatine aponeurosis. Its function is to tense the soft palate,
7:04
as well as widening the auditory tube to release some pressure off from the middle ear.
7:09
Then there’s the Palatoglossus muscle, which is this one.
7:13
This muscle will originate from the palatine aponeurosis and insert at the root of the tongue.
7:19
And its function is to elevate the root of the tongue, and depress the soft palate. By doing so,
7:25
it narrows the opening of the pharynx to assist with the swallowing process. The last muscle is
7:32
the Palatopharyngeus muscle, which is this one. It also originates from the Palatine aponeurosis,
7:38
but it inserts at the lateral wall of the pharynx. SO it’s function is to elevate
7:43
the pharynx and depress the soft palate, which actually also assists with narrowing
7:47
the opening of the pharynx so seal off the pharynx from the oral cavity completely.
7:52
So these 5 are the big guys when it comes to the soft palate. They’re the mian muscles. But these
7:56
two up here are special. The palatopharyngeal and the palatoglossus muscles. The reason why they’re
8:02
special is because the palatoglossal muscle is going to form an arch as it goes from the soft
8:08
palate to the tongue, called the palatoglossal arch. And the palatopharyngeal muscle is going
8:14
to form an arch as it goes from the soft palate to the pharynx, called the palatopharyngeal arch.
8:21
And between these two arches, you’ll find the palatine tonsil, which helps with local immunity.
8:27
And here just to visualize them better, here’s a sideview of those arches along with the
8:32
palatine tonsils. Awesome. So that was all for the anatomy of the hard and soft palate.
8:38
Now let’s talk about the inferior border. The inferior border of the oral cavity proper consists
Inferior Border: Floor of Oral Cavity
8:43
of two things. First is what we call the floor of the oral cavity, which consists of three main
8:50
muscles that primarily go from the inner surface of the mandible, all the way to the hyoid bone.
8:56
These muscles are the Mylohyoid muscle, anterior belly of digastric muscle
9:01
and the geniohyoid muscle. And just to orientate,
9:05
you’ll normally find the submandibular gland below them and the sublingual gland above them.
9:10
So if you lift your tongue up like this. You’ll find the floor of the oral cavity here.
9:16
The other important structure when we talk about the inferior border si the tongue.
Anatomy of the Tongue
9:22
One thing I want you to know about the tongue is that it’s not a muscle, it’s a muscle organ.
9:28
Meaning that it’s composed of several muscles. The other thing is that it’s composed of 3
9:36
main parts. It’s made up of an Apex, which is the tip of the tongue. A body and a root.
9:43
Now let’s look at the Tongue from this perspective and go through some important structures
9:47
associated with the tongue. Now just to orientate.
9:51
Here you see the palatoglossal arch, containing the palatoglossus muscle. Here you see the
9:51
palatopharyngeal arch, containing the palatopharyngeus muscle. And between them is the
10:02
palatine tonsil. And back here is the epiglottis. So. Again. The tongue consists of 3 parts.
10:08
First we have the Root of the Tongue, then there’s the body of the tongue
10:11
and then the apex of the tongue. And the tongue has some important landmarks.
10:16
First there’s a sulcus here in the middle called the median sulcus of the tongue.
10:22
Then more posteriorly, you’ll find another groove called the terminal sulcus,
10:26
which is a V shaped groove that separates the body of the tongue from the root of the tongue.
10:33
At the tip of the terminal sulcus here, you’ll find the foramen caecum of the tongue,
10:38
which is a small depression here. The foramen caecum is a remnant of the thyroglossal duct.
10:46
Which was a canal formed by the descent of the thyroid during development.
10:52
Behind the terminal sulcus is the lingual tonsil which lies at the root of the tongue. The lingual
10:58
tonsil is a diffuse lymphoid tissue located in the submucosal connective tissue that forms
11:05
bumps on the surface of the root of the tongue Behind the lingual tonsil, there’s the right
11:10
and left glossoepiglottic fold. Or sometimes also referred to as the lateral glossoepiglottic fold.
11:17
And what this is that they’re two mucosal folds that connect the tongue to the epiglottis.
11:24
And in the middle, there’s the median epiglottis fold. Between these folds there’s the epiglottic
11:31
vallecula, which are depressions between the lateral and the median glossoepiglottic folds.
11:37
Other things you’ll find is that if you lift up the tongue, you’ll find
11:41
the frenulum of the tongue, which connect the tongue to the floor of the oral cavity.
11:45
On either side of the frenulum, you’ll find a pair of fimbriated folds as well.
11:50
Then on the lower border of the tongue, there’s the sublingual fold, which has
11:55
many small openings for the minor sublingual ducts, coming from the sublingual gland.
12:01
And then there’s the sublingual caruncle. These are two tubercles as you see on either
12:06
side of the frenulum, where the submandibular and the major sublingual glands open into.
12:12
Awesome. Now let’s go through the muscles of the tongue.
12:16
Now the muscles of the tongue are divided into the extrinsic muscles and the intrinsic
Muscles of the Tongue
12:21
muscles. The extrinsic muscles, or the extraglossal muscles originate from bones and
12:28
insert at the tongue. The Intraglossal muscles, or the intrinsic muscles, they originate and insert
12:35
within the tongue. Functionally, the extrinsic muscles focus on movement of the tongue, and the
12:41
intrinsic muscles focus on changing the shape of the tongue. So let’s look at these muscles.
12:47
The first muscle is called Genioglossus muscle, which is this one. It originates
12:52
from the superior mental spine of the mandible and insert at the root of the tongue. And the
12:57
function of this muscle is to pull the tongue forward and depress the tongue.
13:02
Then there’s the styloglossus muscle. This muscle originates from the styloid process.
13:07
So imagine the styloid process here. It goes from the styloid process and then inserts at the
13:14
root of the tongue. Its function is to pull the tongue backwards, as well as elevating the tongue.
13:20
Then we have the Hyoglossus muscle. This one. This muscle originates from the hyoid bone,
13:25
and insert at the root of the tongue. The function is to pull the tongue backwards,
13:30
as well as depressing the tongue. The last muscle depend on the source
13:35
you’re studying from. Some sources say there are 3 extraglossal muscles,
13:40
so they don’t count the palatoglossus muscle, and some sources count the palatoglossus muscle
13:43
as a part of the extrinsic muscles. But we’ll add this to our list because it’s also going to
13:53
aid with movement of the tongue. Remember this is the muscle that originates from the palatine
13:58
aponeurosis of the soft palate and insert at the root of the tongue. Its function is to narrow the
14:06
opening of the oropharynx by elevating the root of the tongue and depressing the soft palate. So
14:11
these are the 4 extrinsic muscles of the tongue. Within the tongue itself. You’ll find the
14:17
Intrinsic muscles. These are the Superior and Inferior longitudinal muscles,
14:23
which run from the apex of the tongue to the root. So its function is to shorten the tongue.
14:29
Then we have the vertical muscles of the tongue, which connect the upper and lower surface,
14:35
and its function is to flatten the tongue. Then we have the transverse muscles of the tongue,
14:40
which arise from the median fibrous septum, and runs laterally to the sides of the tongue,
14:46
and when they contract, they’re gonna narrow the tongue. So that was all the muscles of the
14:52
tongue. Now on the surface of your tongue, you’re gonna have something called lingual papillae,
Lingual Papillae
14:57
which contain taste buds to sense taste. And different parts of the tongue senses different
15:02
taste because you’re gonna have different taste buds on several locations of the tongue.
15:08
First we have the Filiform papilla. They give the tongue its roughness,
15:12
and it has epithelial tissue on the top; It looks quite rough when you look at it.
15:19
Next is the fungiform papilla. Which is a small elevation that carries taste receptor buds.
15:26
The next one is the Vallate papilla. The Vallate papilla is located near the terminal sulcus,
15:31
and this one also contains taste buds. Then we have foliated papilla.
15:35
The foliate papilla also contains taste buds and is located at the lateral region of the tongue.
15:41
So that was all for the inferior border. Posteriorly to the oral cavity proper,
15:46
is the Oropharynx. And between the pharynx and the oral cavity, there’s a narrowing called the
Posterior Border
15:52
isthmus of fauces. Or sometimes referred to as the oropharyngeal isthmus, which is the bordering line
15:58
between the pharynx and the oral cavity proper. And that my friends, is the Oral Cavity Proper.