Description

Larynx: Anatomy, Cartilage, Ligaments, and Function

This video covers the anatomy of the larynx, its cartilage structures, ligaments, and functions related to phonation and respiration.

1. Larynx Orientation:

• Located between the hyoid bone and the trachea.
• Situated in front of the esophagus.
• Skeletopy: Extends from C4-C5 to C6-C7.

Functions of the Larynx:

• Acts as an air passage.
• Produces sound through phonation.

2. Cartilage of the Larynx:

Unpaired Cartilages (3):

• Epiglottis.
• Thyroid Cartilage.
• Cricoid Cartilage.

Paired Cartilages (3):

• Arytenoid Cartilage.
• Corniculate Cartilage.
• Cuneiform Cartilage.

3. Details of Laryngeal Cartilages:

Thyroid Cartilage (Cartilago Thyroidea):

• Right and left laminae (Lamina Dextra and Lamina Sinistra).
• Laryngeal Prominence (Adam’s Apple) (Prominentia Laryngea).
• Superior and inferior horns (Cornua Superiora and Cornua Inferiora).

Cricoid Cartilage (Cartilago Cricoidea):

• Arch (Arcus).
• Plate (Lamina).
• Arytenoid and thyroid articular surfaces (Facies Articularis Arytenoidea & Facies Articularis Thyroidea).

Epiglottis:

• Behind thyroid cartilage and hyoid bone.
• Prevents food from entering the airway during swallowing.

Arytenoid Cartilage (Cartilago Arytenoidea):

• Triangular in shape with apex and base.
• Vocal Process: Anterior process that attaches to the vocal cords.
• Muscular Process: Posterior process for muscle attachment.

Corniculate Cartilage (Cartilago Corniculata):

• Sits on top of the arytenoid cartilage.
• Serves as an attachment for muscles.

Cuneiform Cartilage (Cartilago Cuneiforme):

• Located in the aryepiglottic fold.
• Forms the cuneiform tubercle.

4. Laryngeal Ligaments & Joints:

Connections in the Larynx (Juncturae Laryngis):

Continuous Articulation (Synarthroses):

• Cartilaginous (Synchondroses): Between corniculate cartilage and apex of arytenoid cartilage.
• Fibrous (Syndesmoses):
  • Thyrohyoid Membrane (Membrana Thyrohyoidea).
  • Cricothyroid Membrane (Membrana Cricothyroidea).
  • Cricotracheal Ligament (Ligamentum Cricotracheale).
  • Thyroepiglottic Ligament (Ligamentum Thyroepiglottica).
  • Hyoepiglottic Ligament (Ligamentum Hyoepiglotticum).

Discontinuous Articulation (Synovial):

• Cricothyroid Articulation (Articulatio Cricothyroidea).
• Cricoarytenoid Articulation (Articulatio Cricoarytenoidea).

5. Laryngeal Wall Layers:

Tunica Mucosa:

• Vestibular Fold: Lined by respiratory epithelium.
• Vocal Fold: Lined by stratified squamous epithelium.
• Contains laryngeal glands and lymph nodules.

Tela Submucosa:

• Fibroelastic Membrane (Membrana Fibroelastica Laryngis):
  • Quadrangular Membrane: Forms the vestibular ligament.
  • Lateral Cricothyroid Ligament (Conus Elasticus): Free margin forms the vocal ligament.

Muscles of the Larynx:

• Controls Laryngeal Inlet: Opens and narrows the entrance.
• Controls Rima Glottidis: Adjusts airflow.
• Acts on the Vocal Cord:
  • Cricothyroid Muscle: Tenses the vocal cord.
  • Vocalis Muscle: Decreases tension in the vocal cord.

Tunica Adventitia:

• Dense connective tissue for structural support.

6. Laryngeal Cavity:

• Laryngeal Vestibule (Vestibulum Laryngis).
• Glottis:
  • Rima Glottidis: Opening between the vocal folds.
  • Anterior 3/5: Intermembranous part.
  • Posterior 2/5: Intercartilaginous part.
• Laryngeal Ventricles (Ventriculus Laryngis).
• Infraglottic Cavity.

7. Sources:

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

Transcript

Introduction
0:00
Hey what’s up.
0:02
Meditay here.
0:03
Let’s talk about the anatomy of the respiratory system.
0:08
In this segment, we will be talking about the anatomy of the Larynx.
0:12
Alright, so the respiratory system consist of all the organs involved in breathing.
0:17
These are the Nose, Pharynx, Larynx, Trachea, Bronchi and the Lungs.
0:23
In our last video, we covered the anatomy of the nasal cavity.
0:27
Now let’s do the anatomy of the Larynx.
0:29
So in this video, we’ll start with orientation by looking at the anterior and posterior view
0:35
of the Larynx.
0:36
Then we’ll talk briefly about what cartilages make up the larynx.
0:40
As well as the ligaments and joints that hold the whole thing together.
0:44
Then we’ll do the walls of the Larynx and talk a little bit about what’s special with
0:48
the Laryngeal cavity.
0:49
Alright, so the Larynx is located right about here.
Orientation of the Larynx
0:53
It lies between the Hyoid Bone, and the Trachea.
0:56
And right in front of the Esophagus.
0:58
Topographically, it starts in the region of 4th 5th Cervical Vertebrae, and ends at the
1:04
region of 6th-7th cervical vertebrae.
1:06
Let’s list a few of Larynx’s functions.
1:09
The first is Air passage.
1:11
It serves as a passage, so that air can go down into your lungs.
1:15
Another thing is that your Larynx is also called the Voice Box, because it produces
1:20
sound.
1:21
And it does that through a process called Phonation, where these vocal cords rub into
1:25
each other producing different pitch.
1:27
I’ll go through this at the end of this video.
1:30
Now let’s continue with the orientation by looking at the Larynx from different angles.
1:34
So, if you look at it anteriorly This is how it’s gonna look like.
1:39
And posteriorly This is how it’s gonna look like.
1:43
Notice the hyoid bone above the larynx, and the trachea under it.
Cartilage of the Larynx
1:48
Now let’s start by understanding how the Larynx is built.
1:51
So the Larynx is made up of 6 types cartilages in total.
1:55
3 paired and 3 unpaired Cartilages.
1:58
Cartilages that are unpaired means that you only have one of each, and these are the Epiglottis
2:04
in Purple, Thyroid cartilage, in blue.
2:07
And the cricoid cartilage, here in light green.
2:09
The paired, are the cartilages you have two of.
2:14
These include the Arytenoid cartilage here in yellow, Corniculate cartilage in red, and
2:20
the Cuneiform cartilage, here in green.
2:23
These are the cartilages that make up the Larynx.
2:25
Now let’s switch up to a model from my anatomy program, just to make it look a little more
2:28
realistic.
2:29
We have the Epiglottis, The thyroid cartilage and the Cricoid cartilage.
2:33
We have the Arytenoid, the Corniculate and the Cuneiform cartilages.
2:37
Let’s now cover each of these cartilages and look at their characteristics, we’ll
Thyroid Cartilage
2:43
start with he thyroid cartilage.
2:45
So again here’s an anterior view and a posterior view of the Larynx.
2:49
The thyroid cartilage is highlighted here in blue.
2:52
And just to have an overview, I think it’s better to have a list of the cartilages we’re
2:56
about to cover.
2:57
Now the thyroid cartilage is mainly made up of two plates, or two Laminas.
3:02
There’s the Right lamina, and the Left lamina.
3:05
These two meets in the middle, and form the laryngeal Prominence, which is also known
3:10
as Adam’s apple.
3:11
You’ll notice there are two processes on the thyroid cartilage as well.
3:16
There’s one going straight up towards the Hyoid bone, called the superior horn, and
3:21
a process going down towards the cricoid cartilage, called the inferior horn.
3:25
So that’s the most important structures of the thyroid cartilage for now, let’s
3:29
check that one from our list.
Cricoid Cartilage
3:31
Next is the cricoid cartilage, here in light green located below the thyroid cartilage
3:36
The cricoid cartilage looks different, depending on which side you’re looking from.
3:40
Anteriorly, it has an arch protruding forward, and posteriorly, it has a plate with two important
3:47
surfaces.
3:48
There’s the arytenoid articular surface, which is where the arytenoid cartilage binds
3:53
to the cricoid cartilage forming a joint.
3:56
And it has a Thyroid articular surface, which form a joint with the inferior horn of the
4:01
thyroid cartilage.
4:03
So that’s all for the cricoid cartilage, let’s put a checkmark here.
Epiglottis
4:07
Next is the Epiglottis, which is here in purple.
4:10
It doesn’t really have any specific structure of importance for now.
4:13
But it lies behind the thyroid cartilage and the hyoid bone, and if you look at a posterior
4:19
view.
4:20
It mainly attaches to the thyroid cartilage through ligaments.
4:23
Its function is mainly closing off for the respiratory system when you swallow and open
4:28
up when you’re breathing.
4:29
So that’s the epiglottis.
Arytenoid Cartilages
4:31
Next is the Arytenoid cartilages, which are paired.
4:34
They’re located here in yellow, right above the cricoid cartilage.
4:39
And if you look at them from a sideview, you’ll notice that it has a triangular shape, which
4:44
an Apex on top, and a base.
4:47
The base has two parts, or two processes.
4:50
The anterior process is called the vocal process, since it attaches to the vocal ligament, I’ll
4:56
show you this later.
4:57
The posterior process is called Muscular process, which serves as an attachment point for certain
5:03
muscles.
5:04
And the base of the arytenoid cartilage, is called Cricoid Articular Surface, since it
5:09
sits on the cricoid process.
5:10
So that’s this one.
Corniculate Cartilage
5:11
Next we have the corniculate cartilage, which is here in red, and lie on top of the arytenoid
5:17
cartilage.
5:18
It doesn’t really have any specific function on its own, other that serving as an attachment
5:23
point for certain muscles as well.
5:25
So, let’s tick that one.
Cuneiform Cartilages
5:27
The last cartilages are the Cuneiform cartilages, here highlighted in green.
5:31
They’re two small, elongated pieces of yellow elastic cartilage, which lie in something
5:37
called the aryepiglottic fold.
5:39
The aryepiglottic fold is essentially a fold that lines the entrance of the Larynx.
5:45
And the Cuneiform Cartilage form a tubercle on it, which is visible if you’d examine
5:50
the larynx of a patient.
5:52
This tubercle is called Cuneiform tubercle.
5:54
So, let’s go ahead and tick that one as well.
5:58
So those are the cartilages that make up the Larynx.
Ligaments and Joints
6:01
Now we need to cover the connections in the Larynx, or the Juncturae Laryngis.
6:05
But to really understand these connections, we need to have a basic understanding of the
6:10
different connection forms we have in our body.
6:14
So the articular system in the Larynx si divided into two types of connection.
6:19
There are Continuous articulation, and discontinuous articulation.
6:24
Now what are the differences between those?
6:27
Continuous connections are uninterrupted articular connection, hence the name continuous.
6:33
Discontinuous connections are interrupted in that, it contains a cavity within the articulation,
6:39
which form a joint.
6:40
Now, I like to use the ribs as an example of the continuous connections in the Larynx.
6:45
Because one of the connection types is called cartilaginous, or Synchondroses.
6:50
Which is where you’ll find at the point where the rib meets the costal cartilage,
6:54
called the costochondral synchondroses.
6:57
The other type of continuous connection you’ll find in the Larynx is a fibrous type of connection,
7:02
which form membranes, or Ligaments.
7:05
Very much like the intercostal membrane you see here.
7:10
Discontinuous connections are joints.
7:12
In the Larynx you’ll find two synovial joints, just like this one, which are ligaments forming
7:18
a sac full of synovial fluid.
7:20
Now let’s do the continuous connections of the Larynx first, then do the discontinuous
7:25
connections.
7:26
The Larynx has only one cartilaginous connection point, and that’s between the corniculate
7:32
cartilage and the arytenoid cartilage.
7:35
So here is the Larynx.
7:36
Here is the Corniculate Cartilage, and here is the Arytenoid Cartilage.
7:40
Here is the cartilaginous connection.
7:42
It’s a very dense connection, nearly bony joint.
7:46
For the fibrous connections.
7:47
We have the Thyrohyoid membrane, which is a membrane between the thyroid cartilage and
7:52
the hyoid bone, as you see here, so this in green is the thyrohyoid membrane.
7:57
Theoretically, it has two parts.
7:59
A median Thyrohyoid membrane and a lateral thyrohyoid membrane, as you see here.
8:05
Next we have the Cricothyroid membrane, which lies between the Thyroid cartilage and the
8:09
Cricoid Cartilage.
8:10
So it’s this one.
8:12
The cricothyroid membrane is a membrane that are made up by two ligaments.
8:17
One of them is the median cricothyroid ligament, and the other one is the lateral cricothyroid
8:23
ligament, or conus elasticus.
8:26
The conus elasticus is really important, I’ll talk briefly about it later in this video.
8:32
Then there’s the cricotracheal ligament, between the cricoid cartilage, and the trachea,
8:37
as you see here.
8:38
Then we have the thyroepiglottic ligament, which is this one, connecting the Epiglottis
8:42
to the Thyroid cartilage.
8:44
And then we have the Hyoepiglottic ligament, which connects the Epiglottis to the Hyoid
8:49
bone, as you see here.
8:51
So all of those are the Continuous connections we have in the Larynx.
8:56
Now let’s do the Discontinuous connections.
8:59
We have two synovial joints in the Larynx, and if you really paid attention earlier in
9:04
this video, you’d know these already from when I talked about the cricoid cartilage.
9:09
Because the first one is the cricothyroid articulation, which is a synovial joint between
9:14
the inferior horn of the thyroid cartilage, and the cricoid cartilage.
9:19
The other one is the Cricoarytenoid articulation, between the base of the arytenoid cartilage
9:25
and the cricoid cartilage.
9:27
They look like this, filled with synovial fluid for a nice movement of the larynx.
Laryngeal Wall
9:32
Now.
9:33
Here you see a lateral view of the larynx.
9:35
If we make a vertical cut of the larynx, as you see here.
9:38
And look at it from this view, you’ll see this.
9:41
So, let’s go over some important landmarks.
9:44
There’s the Epiglottis, The thyroid cartilage, the cricoid cartilage, and the hyoid bone.
9:50
And between the cartilages, you’ll find the Thyrohyoid membrane.
9:53
So, let’s now cover the walls of the Larynx.
9:57
The larynx has 4 layers.
9:59
We have the Tunica Mucosa, here in blue.
10:02
Then underneath that, there’s the Tela submucosa, as you see here.
10:05
Then you have a layer of cartilages and muscles, as you see here.
10:08
And lastly, there’s the Tunica adventitia, which are connective tissue covering the surfaces
10:13
of the larynx.
10:14
Now, let’s go through each of these layers and look at their characteristics.
Tunica Mucosa
10:19
We’ll start with Tunica Mucosa.
10:21
So again, the tunica mucosa is here, it’s the innermost lining of the Larynx.
10:27
At the vestibular folds, which is the upper fold, it’s lined by Respiratory epithelium,
10:32
which are epithelium specialized in filtrating the air, as they contain cilia that catches
10:38
small particles before they go further down into your lungs.
10:42
The Vocal folds, are lined by stratified squamous epithelium, which are essentially logical
10:47
because the vocal folds are under a lot fo strain, allowing you to speak loudly and for
10:53
a longer period of time without harming your vocal folds.
10:57
In chronic smokers and people who use their voices a lot like in singers, the respiratory
11:03
epithelium lining the vestibular folds are often damaged and replaced by stratified squamous
11:09
epithelium, which makes them more susceptible for lower respiratory infections, since the
11:15
cilia of the respiratory epithelium are gone.
11:18
So that’s the lining, but the tunica mucosa also contains glands, or laryngeal glands,
11:24
lubricating the surface, and small lymph nodules for immunity.
11:29
So that’s the tunica mucosa.
Tela Submucosa
11:32
Next we have the tela submucosa, which are here.
11:35
Remember earlier when we went through the connections of the Larynx, where we talking
11:38
about the continuous connections, specifically the fibrous membranes of the Larynx?
11:43
Well, at some places the Fibrous membranes form a so called Fibroelastic membrane, which
11:49
are elastic membranes playing a key role in you being able to speak.
11:55
There are two fibroelastic membranes in the Larynx.
11:58
The first one is the Quadrangular Membrane, which are here.
12:01
If we look at a posterior view of the Larynx.
12:03
It’s much easier to see this membrane.
12:05
It’s a membrane that goes between the Vestibular Folds and the Epiglottis, as you see here.
12:11
There’re two margins left that aren’t connected to anything, The upper margin, form
12:17
the aryepiglottic fold, if you remember from earlier, the aryepiglottic fold is a fold
12:22
lining the entrance of the larynx.
12:25
The lower margin forms the vestibular ligament, which is a ligament you see down here, going
12:30
between the arytenoid cartilage and the thyroid cartilage.
12:33
The other fibroelastic membrane we have is the Conus Elasticus, or the Lateral Cricothyroid
12:39
Ligament.
12:40
It’s this one, if you remember it from earlier.
12:43
IF we turn it around, you’ll see that it’s connected to the Cricoid cartilage, the Arytenoid
12:48
cartilage and the thyroid cartilage.
12:51
But it has one free margin, and that’s the upper margin, which form the Vocal ligament.
12:57
This ligament is a part of the vocal fold which is the fold that makes it possible to
13:01
speak once they vibrate, I’ll show you this later.
13:05
So that is the tela submucosa.
Muscles of the Larynx
13:07
Next, we have the Cartilage and Muscle Layer, as you see here.
13:11
We’ve already covered the cartilages, but the muscles of the Larynx are grouped according
13:15
to their function.
13:17
So we have three groups of muscles in the Larynx.
13:20
The first ones are the muscles that open and narrow the laryngeal inlet, or the entrance,
13:26
so this one.
13:27
It opens and narrows this entrance into the Larynx.
13:30
The next ones are the muscles that open and narrow the Rima Glottidis.
13:34
And the Rima glottidis is here, situated between the Vocal folds, or the Vocal Cords.
13:40
The fold superior to the Rima glottidis is called Rima Vestibuli, between the vestibular
13:45
folds.
13:46
And again, don’t forget that the Vocal Ligaments are here, as you remember earlier, formed
13:51
by the superior margin of Conus Elasticus.
13:53
So, the vocal ligament is a part of the vocal cords.
13:57
And the Rima glottidis is between the vocal cords.
14:01
And if we look at the larynx looking from this direction, you’ll see this.
14:05
With the epiglottis here and the aryepiglottic fold here.
14:09
So the vocal ligament is located right about here.
14:12
Always remember that this pointy end is the anterior side, and the rounded one is the
14:18
posterior side.
14:19
Now.
14:20
Rime glottidis is here, between the vocal cords, rima vestibuli, is here, between the
14:26
vestibular folds.
14:27
So, the muscles that open and narrow the rime glottidis, work like this.
14:32
They open, or narrow.
14:33
The rima glottidis.
14:35
The last muscle group are the muscles that act on the vocal cord itself.
14:40
Earlier I told you that the vocal ligament is situated here, but that’s not entirely
14:46
correct.
14:47
Look closely at the structures here.
14:49
The vocal ligament is located within the mucus membranes.
14:53
So the mucus membrane together who the vocal ligament, is what’s referred to as the vocal
14:59
cord, so that’s essentially what I mean by the last group of muscles.
15:03
They act directly on the vocal cord, which essentially is the vocal ligament.
15:09
There are muscles that tenses the vocal cord, such as the cricothyroid muscle.
15:14
This muscle is situated here, as you see.
15:17
And when they contract, they pull the thyroid cartilage to the front, tensing the vocal
15:22
ligament.
15:23
If we look posteriorly, and zoom in.
15:26
When the thyroid cartilage move forward, the vocal cord is tensed.
15:31
The other muscles decrease the tension of the vocal cord, such as vocalis muscle, situated
15:36
right next to the vocal cords, as you see here.
15:39
And when they contract, they pull the arytenoid cartilage forward to decrease the tension
15:45
of the vocal cord.
Tunica Adventitia
15:47
Lastly, we have the Tunica Adventitia.
15:50
So here’s the Larynx.
15:52
Tunica adventitia is a covering around the larynx, which is a tough connective tissue
15:57
consisting mainly of dense collagen fibers.
16:00
So that was the Layers of the Laryngeal Wall, the last thing I wanna talk about in this
Laryngeal Cavity
16:04
video is the Laryngeal Cavity.
16:06
So the Laryngeal Cavity, or Cavitas Laryngis, is this whole cavity here.
16:11
It starts at the Laryngeal Inlet, or entrance, and ends at the lower border of the cricoid
16:17
cartilage.
16:18
But we generally divide it into three landmarks.
16:21
The first one is the Laryngeal Vestibule, going from the laryngeal entrance to the Vestibular
16:26
Folds.
16:27
Then there’s Glottis, between the Vestibular Folds and the Vocal Cords, or the Vocal folds
16:32
it’s a synonym.
16:34
There’s an important thing we need to discuss here.
16:37
Remember, the Rima glottis is here.
16:39
We generally divide this cavity into two parts based on the structures around it.
16:44
The anterior 3/5 is called intermembranous part, since it’s between membranes.
16:50
The posterior 2/5 is intercartilaginous part, situated between cartilages.
16:56
And if we change up to a more realistic one.
16:59
Here you see that the anterior 3/5 of it is between membranes, and the posterior part
17:05
lying between cartilages, between the arytenoids here.
17:08
Now why is this important?
17:10
Because they give you the possibility to speak!
17:12
When you’re speaking, the vocal cords rub into each other, in a process called phonation.
17:18
But when you breath, the folds are open for air to pass through.
17:23
Now when you look closely at the glottis, notice there is a pouch at either side, called
17:28
Laryngeal ventricles, which acts as a resonator.
17:32
It resonates the sound as you speak.
17:34
From the Vocal Cords, we have the Infraglottic cavity, which is until the lower border of
17:41
the cricoid cartilage.
17:42
From this point.
17:43
That’s where your Trachea is going to be.
17:45
And that’s a topic for our next video.