Description

External and Internal Anatomy of the Nose

This video covers the external structures of the nose, the anatomy of the nasal cavity, the functions and openings of sinuses, and the mucosa lining of the nasal cavity. We will also discuss the clinical relevance of conditions such as sinusitis.

1. External Structures of the Nose:

• Root of the Nose (Radix Nasi) – Uppermost part near the forehead.
• Dorsum of Nose (Dorsum Nasi) – Extends from root to apex.
• Apex of Nose (Apex Nasi) – Tip of the nose.
• Ala of Nose / Wing of Nose (Ala Nasi) – Lateral rounded portion surrounding the nostrils.
• Nostrils (Nares) – Openings for airflow into the nasal cavity.

2. Nasal Cartilages:

• Nasal Bones (Os Nasale Dextrum/Sinistrum).
• Lateral Nasal Cartilages (Cartilago Nasi Lateralis).
• Accessory Nasal Cartilage (Cartilagines Nasales Accessoriae).
• Major Alar Cartilage (Cartilagines Alares Majores).
• Minor Alar Cartilage (Cartilagines Alares Minores).
• Septal Nasal Cartilage (Cartilago Septi Nasi).
• Alar Fibrofatty Tissue (Tela Fibroadiposa Alaris).
• Bony Septal Part (Pars Ossea).

3. Anatomy of the Nasal Cavity:

• Located above the palate and in front of the pharynx.

Divisions:

• Nasal Vestibule (Vestibulum Nasi).
• Nasal Cavity Proper (Cavitas Nasi Proprium).
• Limen Nasi – Boundary between vestibule and nasal cavity proper.

Nasal Cavity Proper:

• Olfactory Part (Pars Olfactoria) – Specialized for smell.
• Respiratory Part (Pars Respiratoria) – Warms, humidifies, and filters air.

Olfactory Structures:

• Olfactory Tract (Tractus Olfactorius).
• Olfactory Bulb (Bulbus Olfactorius).
• Olfactory Nerves (Fila Olfactoria).

Respiratory Structures:

• Superior Conchae (Superior Turbinate).
• Middle Conchae (Middle Turbinate).
• Inferior Conchae (Inferior Turbinate).
• Meatuses:
  • Superior Meatus
  • Middle Meatus
  • Inferior Meatus
  • Spheno-Ethmoidal Recess

4. Sinuses and Meatuses:

• Sphenoid Sinus: Opens into the sphenoethmoidal recess.
• Frontal Sinus: Opens into the middle meatus.
• Ethmoidal Sinus:
  • Anterior and Middle Ethmoidal Air Cells → Middle Meatus.
  • Posterior Ethmoidal Air Cells → Superior Meatus.
• Maxillary Sinus: Opens into the middle meatus.
• Nasolacrimal Duct: Opens into the inferior meatus.

Functions of Sinuses:

• Decrease relative mass of the skull.
• Enhance voice resonance.
• Humidify and warm inhaled air.
• Produce mucus to prevent nasal dryness.

5. Nasal Mucosa:

Olfactory Mucosa:

• Olfactory Epithelium – Detects odors.
• Sustentacular Cells – Support cells; damaged in COVID-19, leading to anosmia.
• Basal Cells – Stem cells for regeneration.
• Bowman’s Glands – Produce mucus in the tela submucosa.

Respiratory Mucosa:

• Epithelium: Pseudostratified columnar with cilia.
• Goblet Cells: Produce mucus.
• Tela Submucosa: Contains mixed mucous glands.

6. Clinical Relevance: Sinusitis

Definition: Inflammation of the sinuses due to mucus accumulation and blockage.

Causes:

• Common cold.
• Allergic rhinitis.
• Nasal polyps.
• Deviated nasal septum.

Sources:

• Memorix Anatomy, 2nd Edition by Hudák Radovan, Kachlík David, and Volný Ondřej.
• Complete Anatomy by 3D4Medical.
• Biorender.
• University notes and lectures.

Transcript

Introduction
0:01
Hey what’s up, meditay here.
0:04
Let’s talk about the anatomy of the respiratory system.
0:07
In this segment, we will be talking about the Nasal anatomy.
0:11
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.
0:21
Our goal is to cover the anatomy of all the structures you see here, step by step, and
0:27
we’ll start by covering the detailed anatomy of the nose and nasal cavity.
0:31
So in this video, we’ll start by covering the external structures of the nose, including
0:35
the cartilage.
0:37
Then we’ll split open the head and try to cover the anatomy of the nasal cavity, where
0:41
we’ll be talking about the parts of the nasal cavity, the sinuses, and then talk about
0:45
the layers of the nasal cavity’s wall.
0:47
So let’s now start with the external nose.
External Anatomy of the Nose
0:50
So here you see a side view of the nose.
0:52
There are anatomical names to each of segment of the external nose
0:57
And here each are separated by color.
0:59
So here we have the Root of the nose, the radix nasi.
1:03
Then we have the Dorsum of the nose, and an apex.
1:06
Laterally we have the wings of the nose, or ala nasi, which go around the nostrils.
1:12
Now, if we’d remove the skin and muscle layers, we’ll get to the cartilage and bone.
1:18
The nose is actually build up of bone, cartilage and fat. So the bony part, is called the Nasal bones, the right and left nasal bones
1:25
I’ll show you another scheme after this.
1:29
Under the bones, you’ll find the Lateral nasal cartilages, then there’s the major
1:33
alar cartilage, and the minor alar cartilage.
1:37
And in between the major alar cartilage and the lateral nasal cartilage, you’ll find
1:42
some accessory nasal cartilages supporting the nose.
1:45
And straight in the middle, you’ll find the Septal Nasal Cartilage.
1:49
Now let’s do that again, but in a better model.
1:53
Let’s zoom in to keep you focused on this.
1:56
We have two nasal bones.
1:58
One, Two.
1:59
Then we have the Lateral nasal cartilages, then there’s the major alar cartilage, and
2:04
the minor alar cartilage.
2:05
And in between the major alar cartilage and the lateral cartilage, you’ll find some
2:10
accessory nasal cartilages supporting the nose.
2:14
And straight in the middle, you’ll find the Septal Nasal Cartilage, which divides
2:18
the nose.
2:19
The rest of the nose, is called Alar fibrofatty tissue, which aids by giving the nasal wings
2:25
more flexibility.
2:26
Now.
2:27
Let’s remove all of this, and look at it from a sideview to talk a little bit more
2:30
about the nasal septum.
2:32
As you see here.
2:33
So the nasal septum is here.
2:35
It consists of a Cartilaginous part, and a bony part.
2:39
And they reach all the way to the back of the nasal cavity, until it reached the beginning
2:43
of the pharynx.
2:44
The cartilaginous part is a little bit more flexible than the bony part, which is essentially
2:49
good, giving the nose little bit of flexibility without breaking.
2:53
Now, let’s take the skull, split it in half, and look at it from a side view.
2:58
We’ll see this.
2:59
Let’s now continue with the anatomy of the nasal cavity.
Anatomy of the Nasal Cavity
3:03
Here is the nasal cavity, situated in front of the pharynx, and above the hard palate.
3:08
Under here you’ll find the oral cavity.
3:11
So the nasal cavity is divided into two parts.
3:14
There’s the Nasal Vestibule, as the nostrils, and there’s the nasal cavity proper.
3:19
What separates these two?
3:20
Well, there’s a ridge on the mucosa of the nasal cavity, called the nasal Limen, or Limen
3:27
Nasi, which is generally used as a landmark to separate these two parts.
3:31
Now again, The area just inside the nostril, the nasal vestibule, is supported by the cartilage
3:38
of the nose and lined with tissue that contains hair.
3:41
So the hair you see in your nostrils are only found in the nasal vestibule.
3:46
The rest of the nasal cavity, which is the nasal cavity proper doesn’t have any nasal
3:50
hair.
3:51
It’s lined by mucosa.
3:52
So let’s talk about the nasal cavity proper a little bit.
3:55
The nasal cavity proper is also divided into two parts, since their function differ.
4:00
We divide it into the Olfactory Part for smell, and a Respiratory Part, for breathing.
4:05
Let’s cover these two, starting with the olfactory Part.
Olfactory Part
4:09
The main reason why the olfactory part is able to sense smell, is thanks to your 1st
4:15
cranial nerve that reaches out towards it.
4:17
It has a Olfactory Tract, and a Olfactory Bulb.
4:21
And from the olfactory bulb, there’s gonna be numerous nerves coming down, piercing through
4:26
the ethmoidal bone, which are fibers from the olfactory nerve.
4:31
And if we take a small section, and zoom in a little bit.
4:34
You’ll be able to see how the nerves reach down towards the nasal mucosa.
4:39
There’s gonna be epithelial cells supporting the neurons as they reach down with their
4:44
olfactory receptors aswell.
4:46
Pretty cool process, right?
Respiratory Part
4:47
Now the respiratory part differs a little bit, so let’s go ahead and talk about that.
4:51
The first thing you notice when you look at the respiratory part, are these bumps on the
4:56
nasal mucosa.
4:57
And these are called Conchae, or Turbinates.
4:59
We have a superior Conchae, Middle Conchae and an inferior Conchae.
5:03
And in between them, we have meatuses, which are spaces that have openings for the sinuses.
5:10
There’s the Superior Meatus, between the Superior and middle chonchae, there’s the
5:15
middle meatus, and there’s the inferior meatus, underneath the inferior conchae.
5:20
And above the superior conchae, right at the junction between the sphenoid bone and the
5:24
etmoidal bone, there’s a recess called the Spheno-Etmoidal Recess.
5:29
And here’s an anterior view of the nasal cavity, just to give you a different view
5:34
of these structures Here are the Superior Conchae, Middle Conchae
5:37
and inferior Conchae.
5:39
In between them there’s the Superior Meatus, Middle Meatus, and Infeiror Meatus, and at
5:44
the top here, you’ll find the Spheno-Etmoidal Recess.
5:48
Now.
5:49
Why is this relevant?
Sinuses and Meatuses
5:50
Well, here’s one of the sinuses we have, the sphenoid Sinus.
5:54
It has a tube that opens straight into the sphenoetmoidal recess.
5:59
In front here, we have the frontal sinus, which open into the middle meatus, as you
6:04
see here.
6:05
Then in between the Sphenoid and the Frontal bone, there are the ethmoidal sinus.
6:10
The ethmoidal bone is a little different in that, this sinus has numerous walls within
6:15
the sinus, making air compartments, called ethmoid air cells.
6:20
So the etmoidal air cells are numerous thin-walled cavities .
6:24
They’re generally divided into the anterior etmoidal air cells, middle etmoidal air cells
6:30
and posterior etmoidal air cells.
6:33
The posterior etmoidal air cells, will open up into the Superior Meatus.
6:38
While the Anterior and Middle etmoidal air cells, open up into the Middle meatus.
6:43
So again.
6:43
Posterior etmoidal air cells to superior meatus, and anterior and middle to middle meatus.
6:49
Now, if we look at an anterior view of all the sinuses, you’ll see another sinus, which
6:54
weren’t visible from a lateral view.
6:56
And this one is the Maxillary sinus.
6:58
Which drains into the middle meatus, as you see here.
7:02
Now why do we have these sinuses?
7:04
Well, your skull is pretty heavy, and sinc these sinuses are relative cavities, they
7:09
are thought to decrease the relative mass of the skull, as well as help resonating the
7:14
sound as you speak.
7:16
And since they are lined with mucus with a lot of blood, they’ll also help warming
7:21
up the air and humidifying it as the air goes further down your respiratory system.
7:26
Lastly, and one of very important functions of the sinuses, is to produce mucus, to keep
7:32
the nose from drying out.
7:34
Now, there’s one more structure that open up into the nasal cavity, and that’s the
7:38
lacrimal duct, or the nasolacrimal duct.
7:41
Which lead the tears from the eyes down into the inferior meatus, as you see here.
7:46
Now let’s talk about the nasal mucosa, or the wall of the nasal cavity.
Nasal Mucosa
7:50
Let’s take one section from up here, and one section from down here.
7:55
This is the Olfactory part, and this is the Respiratory part.
7:58
Now I’m not gonna go detailed into the histology of them, but you need to understand some basic
8:04
principles in order to get the full anatomy of the nasal cavity.
8:08
So both parts have a tunica mucosa.
8:11
But the respiratory part have a so called respiratory epithelium, which consist of pseudostratified
8:16
columnar epithelium, which have numerous amount of cilia on them, to catch any type of irritants
8:22
in the air, and trap them so that you can sneeze them out.
8:26
In between the epithelium, you’ll find goblet cells, that produce lubricating mucus on the
8:31
surface.
8:32
And in the Tela submucosa, you’ll find some mucus glands, mixed type pof mucus glands
8:39
that produce mucus.
8:41
The Olfactory Part also has Tunica Mucosa, but here it’s lined by Olfactory Epithelium,
8:47
which consist of Olfactory Cells, which are bipolar neurons with receptors for smell.
8:55
Between these neurons, there are supporting cells called sustentacular cells which are
8:59
tall columnar epithelium that provide support.
9:03
You’ve probably heard by now that the novel corona virus may lead to los of smell.
9:09
And that is because the covid 19 may damage these supporting cells, the sustentacular
9:14
cells.
9:15
This just shows how important the sustentacular cells are to our olfactory nerves.
9:20
Other cells you’ll find in the olfactory mucosa are basal cells, which are essentially
9:25
stem cells to replace the olfactory and sustentacular cells if they get destroyed.
9:31
And on the top here, there are Olfactory cilia, that the olfactory cells give off containing
9:36
receptors.
9:37
In the Tela Submucosa, there are Olfactory Glands, or also called Bowman’s glands,
9:42
which also produce mucus.
9:44
So, as you see each part of the nasal cavity has their own specific function in respiration,
9:50
smelling and even defence against any unwanted particles, since the nasal cavity has so rich
Sinusitis
9:53
blood flow.
9:54
Although sometimes, certain conditions may lead to an excessive inflammation and swelling
9:59
of the nasal and sinus mucosa, leading to an increased secretion of mucus which may block
10:06
the sinuses as you see here.
10:08
These conditions may be caused by the common cold, or certain allergies, where in this
10:13
case certain allergens like pollen, may cause a hypersensitivity response and cause swelling
10:19
of the mucosa. Other causes could be Nasal Polyps which may block the outflow of mucus
10:24
from one of the sinuses, leading to inflammation and sinusitis
10:28
Or even other less common conditions, like a deviated septum, meaning the septum of the
10:33
nose is a little deviated leading to an increase chance of blocking for the sinuses.
10:37
There are of course many reasons for this, but this give you a little bit of understanding
10:42
in regards to why it’s so important to know the meatuses and where the sinuses open up to
10:47
So
10:48
And so that was everything I had regarding the nasal anatomy.
10:51
If you found this video helpful please put a like, share, comment
10:55
whatever you find convinient to you
10:57
The next video will be about the anatomy of the Larynx.