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The nasal cavity is a large, air-filled space above and behind the
nose A nose is a protuberance in vertebrates that houses the nostrils, or nares, which receive and expel air for Respiration (physiology), respiration alongside the mouth. Behind the nose are the olfactory mucosa and the Paranasal sinus, sinuses. Be ...
in the middle of the face. The
nasal septum The nasal septum () separates the left and right airways of the nasal cavity, dividing the two nostrils. It is depressed by the depressor septi nasi muscle. Structure The fleshy external end of the nasal septum is called the columella ...
divides the cavity into two cavities, also known as fossae. Each cavity is the continuation of one of the two
nostril A nostril (or naris , plural ''nares'' ) is either of the two orifices of the nose A nose is a protuberance in vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellular eukaryotic ...
s. The nasal cavity is the uppermost part of the
respiratory system The respiratory system (also respiratory apparatus, ventilatory system) is a biological system A biological system is a complex network Network and networking may refer to: Arts, entertainment, and media * ''Network'' (1976 film), a 1976 Ame ...

respiratory system
and provides the nasal passage for inhaled air from the
nostril A nostril (or naris , plural ''nares'' ) is either of the two orifices of the nose A nose is a protuberance in vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellular eukaryotic ...
s to the
nasopharynx The pharynx (plural: pharynges) is the part of the throat In vertebrate anatomy, the throat is the front part of the neck, positioned in front of the vertebra. It contains the Human pharynx, pharynx and larynx. An important section of it is th ...
and rest of the
respiratory tract The respiratory tract is the subdivision of the respiratory system The respiratory system (also respiratory apparatus, ventilatory system) is a biological system A biological system is a complex network which connects several biologically re ...

respiratory tract
. The
paranasal sinuses Paranasal sinuses are a group of four paired air-filled spaces that surround the nasal cavity The nasal cavity is a large, air-filled space above and behind the nose A nose is a protuberance in vertebrate Vertebrates () comprise all spec ...

paranasal sinuses
surround and drain into the nasal cavity.


Structure

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 The maxilla (plural: ''maxillae'' ) in vertebrates Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological kingdom Animalia. Wit ...

maxilla
. However, there is a deficiency that is compensated for by the perpendicular plate of the
palatine bone In anatomy Anatomy (Greek ''anatomē'', 'dissection') is the branch of concerned with the study of the structure of s and their parts. Anatomy is a branch of natural science which deals with the structural organization of living things. It i ...

palatine bone
, the
medial pterygoid plate The pterygoid processes of the sphenoid (from Greek ''pteryx'', ''pterygos'', "wing"), one on either side, descend perpendicularly from the regions where the body and the greater wings of the sphenoid bone The sphenoid bone is an unpaired bone ...
, the
labyrinth of ethmoid The ethmoidal labyrinth or lateral mass of the ethmoid bone consists of a number of thin-walled cellular cavities, the ethmoid air cells, arranged in three groups, anterior, middle, and posterior, and interposed between two vertical plates of bone ...
and the
inferior concha The inferior nasal concha (inferior turbinated bone or inferior turbinal/turbinate) is one of the three paired nasal conchae in the human nose, nose. It extends horizontally along the lateral wall of the nasal cavity and consists of a wikt:lamina, l ...
. The
paranasal sinus Paranasal sinuses are a group of four paired skeletal pneumaticity, air-filled spaces that surround the nasal cavity. The maxillary sinuses are located under the human eye, eyes; the frontal sinuses are above the eyes; the Ethmoid sinus, ethmoidal ...
es 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 semilunar hiatus or hiatus semilunaris, is a crescent-shaped groove in the lateral wall of the nasal cavity just inferior to the ethmoid bulla. It is the location of the openings for maxillary sinus. It is bounded inferiorly and anteriorly by ...
. The hiatus is bound laterally by a projection known as the
uncinate processAn uncinate process is a hook-shaped projection or protuberance from a bone or organ. It may refer to: * Uncinate process of ethmoid bone, a process located in the nasal cavity * Uncinate process of vertebra, a hook-shaped process on the lateral bor ...
. This region is called the ostiomeatal complex. The roof of each nasal cavity is formed in its upper third to one half by the
nasal bone The nasal bones are two small oblong bone A bone is a Stiffness, rigid tissue (anatomy), tissue that constitutes part of the skeleton in most vertebrate animals. Bones protect the various organs of the body, produce red blood cell, red and whi ...

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 human nose is the most protruding part of the face. It bears the nostrils and is the first organ of the respiratory system. It is also the principal organ in the olfactory system. The shape of the nose is determined by the nasal bones an ...
. 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. The vestibule is enclosed by the
cartilage Cartilage (cartilaginous tissue) is a resilient and smooth elastic tissue Elastic is a word often used to describe or identify certain types of elastomer An elastomer is a polymer A polymer (; Greek ''wikt:poly-, poly-'', "many" + ''wikt:-m ...

cartilage
s of the nose and lined by the same
epithelium Epithelium is one of the four basic types of animal Animals (also called Metazoa) are multicellular A multicellular organism is an organism In biology, an organism () is any organic, life, living system that functions as ...
of the
skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other cuticle, animal coverings, such as the arthropod exoskeleton, have differ ...

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 The respiratory tract is the subdivision of the respiratory system The respiratory system (also respiratory apparatus, ventilatory system) is a biological system A biological system is a complex network which connects several biologically re ...

respiratory tract
. Inside the
nostril A nostril (or naris , plural ''nares'' ) is either of the two orifices of the nose A nose is a protuberance in vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellular eukaryotic ...
s of the vestibule are the
nasal hair#REDIRECT Nasal hair Nasal hair or nose hair, is the hair in the human nose. Adult humans have hair in the nostrils. Nasal hair functions include filtering foreign particles from entering the nasal cavity, and collecting moisture. In support of the ...

nasal hair
, which filter dust and other matter that are breathed in. The back of the cavity blends, via the
choanae The choanae (singular choana), posterior nasal apertures or internal nostrils are two openings found at the back of the nasal passage between the nasal cavity The nasal cavity is a large, air-filled space above and behind the nose A nose is ...
, into the
nasopharynx The pharynx (plural: pharynges) is the part of the throat In vertebrate anatomy, the throat is the front part of the neck, positioned in front of the vertebra. It contains the Human pharynx, pharynx and larynx. An important section of it is th ...
. The nasal cavity is divided in two by the vertical
nasal septum The nasal septum () separates the left and right airways of the nasal cavity, dividing the two nostrils. It is depressed by the depressor septi nasi muscle. Structure The fleshy external end of the nasal septum is called the columella ...
. On the side of each nasal cavity are three horizontal outgrowths called
nasal concha In anatomy Anatomy (Greek ''anatomē'', 'dissection') is the branch of biology concerned with the study of the structure of organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any in ...
e (singular "concha") or turbinates. These turbinates disrupt the airflow, directing air toward the
olfactory epithelium The olfactory epithelium is a specialized epithelium, epithelial tissue inside the nasal cavity that is involved in olfaction, smell. In humans, it measures 9 cm2 and lies on the roof of the nasal cavity about 7 cm above and behind the n ...
on the surface of the turbinates and the septum. The
vomeronasal organ The vomeronasal organ (VNO), or Jacobson's organ, is the paired auxiliary olfactory Olfaction, or the sense of smell, is the special sense through which smells (or odors) are perceived. It occurs when an odor binds to a olfactory receptor, re ...

vomeronasal organ
is located at the back of the
septum In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechanisms ...

septum
and has a role in
pheromone A pheromone (from Ancient Greek ' "to bear" and hormone) is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the s ...

pheromone
detection.


Segments

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 respiratory system (also respiratory apparatus, ventilatory system) is a biological system A biological system is a complex network which connects several biologically relevant entities. Biological organization spans several scales and are d ...
). 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 Cycle or cyclic may refer to: Anthropology and social sciences * Cyclic history, a theory of history * Cyclical theory, a theory of American political history associated with Arthur Schlesinger, Sr. * Social cycle, various cycles in social scienc ...

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 The olfactory epithelium is a specialized epithelium, epithelial tissue inside the nasal cavity that is involved in olfaction, smell. In humans, it measures 9 cm2 and lies on the roof of the nasal cavity about 7 cm above and behind the n ...
, which contains
receptors Receptor may refer to: *Sensory receptor, in physiology, any structure which, on receiving environmental stimuli, produces an informative nerve impulse *Receptor (biochemistry), in biochemistry, a protein molecule that receives and responds to a ne ...
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 Olfactory glands, also known as Bowman's glands, are a type of nasal gland situated in the olfactory mucosa, beneath the olfactory epithelium, in the lamina propria, a connective tissue also containing fibroblasts, blood vessels and bundles of fin ...
. The axons of the bipolar neurons form the
olfactory nerve The olfactory nerve is typically considered the first cranial nerve, or simply CN I, that contains sensory nerve fibers relating to the sense of smell. The afferent nerve fibers of the olfactory receptor neurons transmit nerve impulses abou ...
(cranial nerve I) which enters the brain through the
cribriform plate In mammalian anatomy, the cribriform plate, horizontal lamina or lamina cribrosa (from Latin ''cribrum'', "sieve" + -form) of the ethmoid bone is received into the ethmoidal notch of the frontal bone and roofs in the nasal cavity, nasal cavitie ...
. Bowman's glands are serous glands in the lamina propria, whose secretions trap and dissolve odoriferous substances.


Blood supply

There is a rich blood supply to the nasal cavity. In some animals, such as
dog The dog or domestic dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a Domestication, domesticated descendant of the wolf which is characterized by an upturning tail. The dog Origin of the domestic dog, derived from an Pleistocene ...

dog
s, the
capillary A capillary is a small blood vessel The blood vessels are the components of the circulatory system The circulatory system, also called the cardiovascular system or the vascular system, is an organ system that permits blood to circulate ...

capillary
beds flowing through the nasal cavity help cool the blood flow to the
brain A brain is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's tis ...

brain
. Blood supply comes from branches of both the
internal Internal may refer to: *InternalityAn internality is the long-term benefit or cost to an individual that they do not consider when making the decision to consume a good or service. One way this is related to behavioral economics is by means of the c ...

internal
and
external carotid artery The external carotid artery is a major artery An artery (plural arteries) () is a blood vessel that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two e ...

external carotid artery
, including branches of the
facial artery The facial artery (external maxillary artery in older texts) is a branch of the external carotid artery The external carotid artery is a major artery of the head and neck. It arises from the common carotid artery when it splits into the external ...
and
maxillary artery Maxillary means "related to the maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone A bone is a Stiffness, rigid tissue (anatomy), tissue that constitutes part of the vertebrate s ...
. The named arteries of the nose are: *
Sphenopalatine artery The sphenopalatine artery (nasopalatine artery) is an artery An artery (plural arteries) () is a blood vessel that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blo ...
and
greater palatine artery The greater palatine artery is a branch of the descending palatine artery (a terminal branch of the maxillary artery) and contributes to the blood supply of the hard palate and nasal septum. Course The descending palatine artery branches off of th ...
, branches of the maxillary artery. *
Anterior ethmoidal artery The anterior ethmoidal artery, is a branch of the ophthalmic artery The ophthalmic artery (OA) is the first branch of the internal carotid artery The internal carotid artery (Latin: arteria carotis interna) is located in the inner side of the neck ...
and
posterior ethmoidal artery The posterior ethmoidal artery is an artery of the head which supplies the nasal septum. It is smaller than the anterior ethmoidal artery. Course Once branching from the ophthalmic artery, it passes between the upper border of the medial rectus mus ...
, branches of the
ophthalmic artery The ophthalmic artery (OA) is the first branch of the internal carotid artery The internal carotid artery (Latin: arteria carotis interna) is located in the inner side of the neck in contrast to the external carotid artery. In human anatomy, they a ...
*Septal branches of the
superior labial artery The superior labial artery (superior labial branch of facial artery) is larger and more egregious than the inferior labial artery. It follows a similar course along the edge of the upper lip, lying between the mucous membrane and the orbicularis or ...
, a branch of the
facial artery The facial artery (external maxillary artery in older texts) is a branch of the external carotid artery The external carotid artery is a major artery of the head and neck. It arises from the common carotid artery when it splits into the external ...
, which supplies the vestibule of the nasal cavity.


Nerve supply

Innervation A nerve is an enclosed, cable-like bundle of fibers (called axons) in the peripheral nervous system. A nerve transmits electrical impulses. It is the basic unit of the peripheral nervous system. A nerve provides a common pathway for the electro ...

Innervation
of the nasal cavity responsible for the
sense of smell The sense of smell, or olfaction, is the special sense In medicine Medicine is the Art (skill), art, science, and Praxis (process) , practice of caring for a patient and managing the diagnosis, prognosis, Preventive medicine, prevention, the ...
is via the
olfactory nerve The olfactory nerve is typically considered the first cranial nerve, or simply CN I, that contains sensory nerve fibers relating to the sense of smell. The afferent nerve fibers of the olfactory receptor neurons transmit nerve impulses abou ...
, which sends microscopic fibers from the
olfactory bulb The olfactory bulb (Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Roman Republi ...
through the
cribriform plate In mammalian anatomy, the cribriform plate, horizontal lamina or lamina cribrosa (from Latin ''cribrum'', "sieve" + -form) of the ethmoid bone is received into the ethmoidal notch of the frontal bone and roofs in the nasal cavity, nasal cavitie ...
to reach the top of the nasal cavity. General sensory innervation is by branches of the
trigeminal nerve The trigeminal nerve (the fifth cranial nerve, or simply CN V) is a nerve responsible for sensation in the face and motor functions such as biting and chewing; it is the most complex of the cranial nerves Cranial nerves are the nerve A ner ...

trigeminal nerve
(V1 & V2): *
Nasociliary nerve The nasociliary nerve is a branch of the ophthalmic nerve, itself a branch of the trigeminal nerve The trigeminal nerve (the fifth cranial nerve, or simply CN V) is a nerve responsible for sensation in the face and motor functions such as bitin ...
(V1) *
Nasopalatine nerve One branch of the pterygopalatine ganglion (trigeminal nerve, maxillary nerve, maxillary branch), longer and larger than the others, is named the nasopalatine nerve (sometimes called the long sphenopalatine nerve). It enters the nasal cavity throug ...
(V2) *Posterior nasal branches of
Maxillary nerve The maxillary nerve (V2) is one of the three branches or divisions of the trigeminal nerve The trigeminal nerve (the fifth cranial nerve, or simply CN V) is a nerve responsible for sensation in the face and motor functions such as biting and c ...

Maxillary nerve
(V2) The nasal cavity is innervated by autonomic fibers. Sympathetic innervation to the blood vessels of the mucosa causes them to
constrict
constrict
, while the control of secretion by the mucous glands is carried on
postganglionic In the autonomic nervous system The autonomic nervous system (ANS), formerly the vegetative nervous system, is a division of the peripheral nervous system that supplies smooth muscle and glands, and thus influences the function of viscera, in ...
parasympathetic The parasympathetic nervous system (PSNS) is one of the three divisions of the autonomic nervous system, the others being the sympathetic nervous system and the enteric nervous system. The enteric nervous system is sometimes considered part of t ...
nerve fibers originating from the
facial nerve The facial nerve (the labyrinthine segment) is the seventh Cranial nerves, cranial nerve, or simply CN VII. It emerges from the pons of the brainstem, controls the muscles of facial expression, and functions in the conveyance of taste sensation ...

facial nerve
.


Function

The two nasal cavities condition the air to be received by the other areas of the
respiratory tract The respiratory tract is the subdivision of the respiratory system The respiratory system (also respiratory apparatus, ventilatory system) is a biological system A biological system is a complex network which connects several biologically re ...

respiratory tract
. Owing to the large surface area provided by the
nasal concha In anatomy Anatomy (Greek ''anatomē'', 'dissection') is the branch of biology concerned with the study of the structure of organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any in ...
e (also known as turbinates), the air passing through the nasal cavity is warmed or cooled to within 1 degree of
body temperature Thermoregulation is the ability of an organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous system that embodies the Life#Biology, properties of life. It is a sy ...
. In addition, the air is humidified, and dust and other particulate matter is removed by
nasal hair#REDIRECT Nasal hair Nasal hair or nose hair, is the hair in the human nose. Adult humans have hair in the nostrils. Nasal hair functions include filtering foreign particles from entering the nasal cavity, and collecting moisture. In support of the ...

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 The cilium (; the plural is cilia) is an organelle In cell biology Cell biology (also cellular biology or cytology) is a branch of biology Biology is the natural science that studies life and living organisms, including their anatomy, ...

cilia
of the
respiratory epithelium The respiratory system (also respiratory apparatus, ventilatory system) is a biological system A biological system is a complex network which connects several biologically relevant entities. Biological organization spans several scales and are d ...
move the secreted mucus and particulate matter posteriorly towards the
pharynx The pharynx (plural: pharynges) is the part of the throat behind the human mouth, mouth and nasal cavity, and above the esophagus and trachea – the tubes going down to the stomach and the lungs. It is found in vertebrates and invertebrates, thou ...
where it passes into the
esophagus The esophagus (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. Currently, American E ...

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 The choanae (singular choana), posterior nasal apertures or internal nostrils are two openings found at the back of the nasal passage between the nasal cavity The nasal cavity is a large, air-filled space above and behind the nose A nose is ...
.


Clinical significance

Diseases of the nasal cavity include
viral
viral
,
bacteria Bacteria (; common noun bacteria, singular bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typ ...

bacteria
l and
fungal A fungus (plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the values of the grammatical number, grammatical category of number. The plural of a noun typically denotes a quantity great ...

fungal
infections, nasal cavity
tumors A neoplasm () is a type of abnormal and excessive growth of Tissue (biology), tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissu ...

tumors
, both benign and much more often malignant, as well as inflammations of the
nasal mucosa The nasal mucosa lines the nasal cavity The nasal cavity is a large, air-filled space above and behind the nose A nose is a protuberance in vertebrates that houses the nostrils, or nares, which receive and expel air for Respiration (physio ...
. Many problems can affect the nose, including: *
Deviated septum Nasal septum deviation is a physical disorder of the nose A nose is a protuberance in vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingd ...
- a shifting of the wall that divides the nasal cavity into halves *
Nasal polyps Nasal polyps (NP) are benign tumor, noncancerous growths within the nose or paranasal sinus, sinuses. Symptoms include trouble breathing through the nose, loss of smell, decreased taste, post nasal drip, and a runny nose. The growths are Polyp (me ...
- soft growths that develop on the lining of the nose or sinuses *
Nosebleeds A nosebleed, also known as epistaxis, is bleeding from the human nose, nose. Blood can also flow down into the stomach and cause nausea and vomiting. In more severe cases, blood may come out of both nostrils. Rarely, bleeding may be so significa ...
*
Rhinitis Rhinitis, also known as coryza, is irritation and inflammation of the mucous membrane inside the nose A nose is a protuberance in vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multic ...
- inflammation of the nose and sinuses sometimes caused by
allergies Allergies, also known as allergic diseases, are a number of conditions caused by hypersensitivity Hypersensitivity (also called hypersensitivity reaction or intolerance) refers to undesirable reactions produced by the normal immune system, i ...

allergies
. The main symptom is a runny nose. *
Nasal fracture A nasal fracture, commonly referred to as a broken nose, is a fracture of one of the bone A bone is a Stiffness, rigid tissue (anatomy), tissue that constitutes part of the vertebrate skeleton in animals. Bones protect the various organs of ...
s, also known as a broken nose *
Common cold The common cold, also known simply as a cold, is a viral infectious disease An infection is the invasion of an organism's body Tissue (biology), tissues by Pathogen, disease-causing agents, their multiplication, and the reaction of host (b ...
* Sinonasal tumors


See also

*
Nasal irrigation
Nasal irrigation
* Danger triangle of the face


References


External links

* * Gross anatomy dissection of the nasal cavity, vide

an

{{DEFAULTSORT:Nasal Cavity Nose Olfactory system Respiratory system Sensory organs