Large, air-filled space above and behind the nose in the middle of the face
The
nasal cavity
is a large, air-filled space above and behind the
nose
in the middle of the
face
. The
nasal septum
divides the cavity into two cavities,
[1]
also known as
fossae
.
[2]
Each cavity is the continuation of one of the two
nostrils
. The nasal cavity is the uppermost part of the
respiratory system
and provides the
nasal passage
for inhaled air from the
nostrils
to the
nasopharynx
and rest of the
respiratory tract
.
The
paranasal sinuses
surround and drain into the nasal cavity.
Structure
[
edit
]
The term "nasal cavity" can refer to each of the two cavities of the nose, or to the two sides combined.
The lateral wall of each nasal cavity mainly consists of the
maxilla
. However, there is a deficiency that is compensated for by the perpendicular plate of the
palatine bone
, the
medial pterygoid plate
, the
labyrinth of ethmoid
and the
inferior concha
. The
paranasal sinuses
are connected to the nasal cavity through small orifices called
ostia
. Most of these ostia communicate with the nose through the lateral nasal wall, via a semi-lunar depression in it known as the
semilunar hiatus
. The hiatus is bound laterally by a projection known as the
uncinate process
. This region is called the
ostiomeatal complex
.
[3]
The roof of each nasal cavity is formed in its upper third to one half by the
nasal bone
and more inferiorly by the junctions of the upper lateral cartilage and nasal septum. Connective tissue and skin cover the bony and cartilaginous components of the
nasal dorsum
.
The floor of the nasal cavities, which also form the roof of the mouth, is made up by the bones of the hard palate: the horizontal plate of the palatine bone posteriorly and the palatine process of the maxilla anteriorly. The most anterior part of the nasal cavity is the
nasal vestibule
.
[4]
The vestibule is enclosed by the
nasal cartilages
and lined by the same
epithelium
of the
skin
(stratified squamous, keratinized). Within the vestibule, this changes into the typical respiratory epithelium that lines the rest of the nasal cavity and
respiratory tract
. Inside the
nostrils
of the vestibule are the
nasal hair
, which filter dust and other matter that are breathed in. The back of the cavity blends, via the
choanae
, into the
nasopharynx
.
The nasal cavity is divided in two by the vertical
nasal septum
. On the side of each nasal cavity are three horizontal outgrowths called
nasal conchae
(singular "concha") or turbinates. These turbinates disrupt the airflow, directing air toward the
olfactory epithelium
on the surface of the turbinates and the septum. The
vomeronasal organ
is located at the back of the
septum
and has a role in
pheromone
detection.
The nasal cavity has a
nasal valve area
that includes an
external nasal valve
and an
internal nasal valve
. The external nasal valve is bounded medially by the
columella
, laterally by the
lateral nasal cartilage
, and posteriorly by the nasal sill.
[5]
The internal nasal valve is bounded laterally by the caudal border of the lateral nasal cartilage, medially by the dorsal
nasal septum
, and inferiorly by the anterior border of the
inferior turbinate
.
[6]
The internal nasal valve is the narrowest region of the nasal cavity and is the primary site of nasal resistance.
[7]
Segments
[
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]
The nasal cavity is divided into two segments: the respiratory segment and the olfactory segment.
- The respiratory segment comprises most of each nasal cavity, and is lined with ciliated pseudostratified columnar epithelium (also called
respiratory epithelium
). The conchae, or turbinates, are located in this region. The turbinates have a very vascularized lamina propria (erectile tissue) allowing the venous plexuses of their mucosa to engorge with blood, restricting airflow and causing air to be directed to the other side of the nose, which acts in concert by shunting blood out of its turbinates. This
cycle
occurs approximately every two and a half hours.
- The olfactory segment is lined with a specialized type of pseudostratified columnar epithelium, known as
olfactory epithelium
, which contains
receptors
for the sense of the smell. This segment is located in and beneath the mucosa of the roof of each nasal cavity and the medial side of each middle turbinate. Histological sections appear yellowish-brown due to the presence of lipofuscin pigments. Olfactory mucosal cell types include bipolar neurons, supporting (sustentacular) cells, basal cells, and
Bowman's glands
. The axons of the bipolar neurons form the
olfactory nerve
(cranial nerve I) which enters the brain through the
cribriform plate
. Bowman's glands are serous glands in the lamina propria, whose secretions trap and dissolve odoriferous substances.
Blood supply
[
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]
There is a rich blood supply to the nasal cavity.
Blood supply comes from branches of both the
internal
and
external carotid artery
, including branches of the
facial artery
and
maxillary artery
. The named arteries of the nose are:
Nerve supply
[
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]
Innervation
of the nasal cavity responsible for the
sense of smell
is via the
olfactory nerve
, which sends microscopic fibers from the
olfactory bulb
through the
cribriform plate
to reach the top of the nasal cavity.
General sensory innervation is by branches of the
trigeminal nerve
(V
1
and V
2
):
The nasal cavity is innervated by autonomic fibers.
Sympathetic
innervation to the blood vessels of the mucosa causes them to
constrict
, while the control of secretion by the
mucous glands
is carried on
postganglionic
parasympathetic
nerve fibers originating from the
facial nerve
.
Function
[
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]
The two nasal cavities condition the air to be received by the other areas of the
respiratory tract
. Owing to the large surface area provided by the
nasal conchae
(also known as turbinates), the air passing through the nasal cavity is warmed or cooled to within 1 degree of
body temperature
. In addition, the air is humidified, and dust and other particulate matter is removed by
nasal hair
in the nostrils. The entire mucosa of the nasal cavity is covered by a blanket of mucus, which lies superficial to the microscopic cilia and also filters inspired air. The
cilia
of the
respiratory epithelium
move the secreted mucus and particulate matter posteriorly towards the
pharynx
where it passes into the
esophagus
and is digested in the stomach. The nasal cavity also houses the sense of smell and contributes greatly to taste sensation through its posterior communication with the mouth via the
choanae
.
Clinical significance
[
edit
]
| This section
needs expansion
. You can help by
adding to it
.
(
February 2011
)
|
Diseases of the nasal cavity include
viral
,
bacterial
and
fungal
infections, nasal cavity
tumors
, both benign and much more often malignant, as well as inflammations of the
nasal mucosa
.
Many problems can affect the nose, including:
See also
[
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]
References
[
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]
- ^
Standring S (2016).
Gray's Anatomy: The Anatomical Basis of Clinical Practice
(Forty-first ed.). Elsevier. pp. 556?565.
ISBN
978-0-7020-5230-9
.
- ^
"Nasal fossa"
.
TheFreeDictionary.com
.
- ^
Knipe H.
"Ostiomeatal complex"
.
Radiology Reference Article
. Radiopaedia.org.
- ^
Beitler JJ, McDonald MW, Wadsworth JT, Hudgins PA (2016). "Sinonasal Cancer".
Clinical Radiation Oncology
. Elsevier. pp. 673?697.e2.
doi
:
10.1016/b978-0-323-24098-7.00036-8
.
ISBN
978-0-323-24098-7
.
The nasal vestibules are the two entry points into the nasal cavity. Each is a triangle-shaped space situated in front of the limen nasi and defined laterally by the lateral crus and alar fibrofatty tissue, medially by the medial crus of the alar cartilage and the nasal septum and the distal end of the cartilaginous septum, and columella.
- ^
Hamilton, Grant S. (May 2017).
"The External Nasal Valve"
.
Facial Plastic Surgery Clinics of North America
.
25
(2): 179?194.
doi
:
10.1016/j.fsc.2016.12.010
.
ISSN
1558-1926
.
PMID
28340649
.
- ^
Murthy, V. Ashok; Reddy, R. Raghavendra; Pragadeeswaran, K. (August 2013).
"Internal Nasal Valve and Its Significance"
.
Indian Journal of Otolaryngology and Head & Neck Surgery
.
65
(Suppl 2): 400?401.
doi
:
10.1007/s12070-013-0618-x
.
ISSN
2231-3796
.
PMC
3738809
.
PMID
24427685
.
- ^
Fraioli, Rebecca E.; Pearlman, Steven J. (2013-09-01).
"A Patient With Nasal Valve Compromise"
.
JAMA Otolaryngology?Head & Neck Surgery
.
139
(9): 947?950.
doi
:
10.1001/jamaoto.2013.4163
.
ISSN
2168-6181
.
PMID
24051751
.
- ^
Moore KL, Dalley AF (1999).
Clinically Oriented Anatomy
(Fourth ed.). Philadelphia: Lippincott Williams & Wilkins.
ISBN
978-0-683-06141-3
.
- ^
Schwartz JS, Tajudeen BA, Kennedy DW (2019). "Diseases of the nasal cavity".
Smell and Taste
. Handbook of Clinical Neurology. Vol. 164. pp. 285?302.
doi
:
10.1016/B978-0-444-63855-7.00018-6
.
ISBN
978-0-444-63855-7
.
PMC
7151940
.
PMID
31604553
.
External links
[
edit
]
- lesson9
at The Anatomy Lesson by Wesley Norman (Georgetown University)
- Gross anatomy dissection of the nasal cavity, video
[1]
and
[2]