Nasal cavity
Encyclopedia
The nasal cavity is a large air filled space above and behind the nose
in the middle of the face.
. Owing to the large surface area provided by the nasal conchae, 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 vibrissae
, short, thick hairs, present in the vestibule
. The cilia of the respiratory epithelium
move the particulate matter towards the pharynx
where it passes into the esophagus
and is digested in the stomach.
, however there is a deficiency that is compensated by: the perpendicular plate of the palatine bone
, the medial pterygoid plate
, the labyrinth of the ethmoid
and the inferior concha.
The nasal cavity is enclosed by the butox.
The floor of the nasal cavity, which forms 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. To the front of the nasal cavity is the nose, while the back blends, via the choanae, into the nasopharynx
. The paranasal sinus
es are connected to the nasal cavity through small orifices called ostia.
The nasal cavity is divided in two by a vertical fin called the nasal septum
. On the sides of the 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.
along the inside wall of the nasal cavity trap and remove dust and pathogens from the air as it flows through the nasal cavity. The cilia move the mucus down the nasal cavity to the pharynx, where it can be swallowed.
s, the capillary
beds flowing through the nasal cavity help cool the blood flow to the brain
.
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:
, which sends microscopic fibers from the olfactory bulb
through the cribiform plate to reach the top of the nasal cavity.
General sensory innervation is by branches of the trigeminal nerve
(V1 & V2):
There are two passages in the nasal cavity, not to be confused with nostrils.The entire 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
.
, bacteria
l and fungal
infections, nasal cavity tumors, both benign and much more often malign, as well as inflammations of the nasal mucosa.
Human nose
The visible part of the human nose is the protruding part of the face that bears the nostrils. The shape of the nose is determined by the ethmoid bone and the nasal septum, which consists mostly of cartilage and which separates the nostrils...
in the middle of the face.
Function
The nasal cavity conditions the air to be received by the other areas of the respiratory tractRespiratory tract
In humans the respiratory tract is the part of the anatomy involved with the process of respiration.The respiratory tract is divided into 3 segments:*Upper respiratory tract: nose and nasal passages, paranasal sinuses, and throat or pharynx...
. Owing to the large surface area provided by the nasal conchae, 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 vibrissae
Vibrissae
Vibrissae , or whiskers, are specialized hairs usually employed for tactile sensation. The term may also refer to the thick hairs found inside human nostrils, but these have no sensorial function and only operate as an airborne particulate barrier...
, short, thick hairs, present in the vestibule
Nasal vestibule
Nasal Vestibule is the most anterior part of the nasal cavity. It is enclosed by the cartilages of nose and lined by the same epithelium of the skin . The other part of the nasal cavity, which is lined by the respiratory epithelium, is called nasal cavity proper...
. The cilia of the respiratory epithelium
Respiratory epithelium
Respiratory epithelium is a type of epithelium found lining the respiratory tract, where it serves to moisten and protect the airways. It also functions as a barrier to potential pathogens and foreign particles, preventing infection and tissue injury by action of the mucociliary escalator.-...
move the particulate matter towards the pharynx
Human pharynx
The human pharynx is the part of the throat situated immediately posterior to the mouth and nasal cavity, and anterior to the esophagus and larynx. The human pharynx is conventionally divided into three sections: the nasopharynx , the oropharynx , and the laryngopharynx...
where it passes into the esophagus
Esophagus
The esophagus is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. During swallowing, food passes from the mouth through the pharynx into the esophagus and travels via peristalsis to the stomach...
and is digested in the stomach.
Walls
The lateral wall of the nasal cavity is mainly made up by the maxillaMaxilla
The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...
, however there is a deficiency that is compensated by: the perpendicular plate of the palatine bone
Palatine bone
The palatine bone is a bone in many species of the animal kingdom, commonly termed the palatum .-Human anatomy:...
, the medial pterygoid plate
Medial pterygoid plate
The medial pterygoid plate of the sphenoid is narrower and longer than the lateral pterygoid plate; it curves lateralward at its lower extremity into a hook-like process, the pterygoid hamulus, around which the tendon of the Tensor veli palatini glides.The lateral surface of this plate forms part...
, the labyrinth of the ethmoid
Labyrinth of ethmoid
The Labyrinth or Lateral Mass of the ethmoid bone consists of a number of thin-walled cellular cavities, the ethmoidal cells, arranged in three groups, anterior, middle, and posterior, and interposed between two vertical plates of bone; the lateral plate forms part of the orbit, the medial plate...
and the inferior concha.
The nasal cavity is enclosed by the butox.
The floor of the nasal cavity, which forms 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. To the front of the nasal cavity is the nose, while the back blends, via the choanae, into the nasopharynx
Nasopharynx
The nasopharynx is the uppermost part of the pharynx. It extends from the base of the skull to the upper surface of the soft palate; it differs from the oral and laryngeal parts of the pharynx in that its cavity always remains patent .-Lateral:On its lateral wall is the pharyngeal ostium of the...
. The paranasal sinus
Paranasal sinus
Paranasal sinuses are a group of four paired air-filled spaces that surround the nasal cavity , above and between the eyes , and behind the ethmoids...
es are connected to the nasal cavity through small orifices called ostia.
The nasal cavity is divided in two by a vertical fin called the nasal septum
Nasal septum
The nasal septum separates the left and right airways in the nose, dividing the two nostrils.It is depressed by the Depressor septi nasi muscle.-Composition:The fleshy external end of the nasal septum is sometimes also called columella....
. On the sides of the nasal cavity are three horizontal outgrowths called nasal conchae (singular "concha") or turbinates. These turbinates disrupt the airflow, directing air toward the olfactory epithelium
Olfactory epithelium
The olfactory epithelium is a specialized epithelial tissue inside the nasal cavity that is involved in smell. In humans, it measures about 1 square centimetre and lies on the roof of the nasal cavity about 7 cm above and behind the nostrils...
on the surface of the turbinates and the septum. The vomeronasal organ
Vomeronasal organ
The vomeronasal organ , or Jacobson's organ, is an auxiliary olfactory sense organ that is found in many animals. It was discovered by Frederik Ruysch and later by Ludwig Jacobson in 1813....
is located at the back of the septum and has a role in pheromone
Pheromone
A pheromone is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting outside the body of the secreting individual to impact the behavior of the receiving individual...
detection.
Cilia and mucus
Cilia and mucusMucus
In vertebrates, mucus is a slippery secretion produced by, and covering, mucous membranes. Mucous fluid is typically produced from mucous cells found in mucous glands. Mucous cells secrete products that are rich in glycoproteins and water. Mucous fluid may also originate from mixed glands, which...
along the inside wall of the nasal cavity trap and remove dust and pathogens from the air as it flows through the nasal cavity. The cilia move the mucus down the nasal cavity to the pharynx, where it can be swallowed.
Segments
The nasal cavity is divided into two segments: the respiratory segment and the olfactory segment.- The respiratory segment is lined with ciliated pseudostratified columnar epithelium (also called respiratory epithelium). The conchae are located in this region. The respiratory segment has a very vascularized lamina propria allowing the venous plexuses of the conchal mucosa to engorge with blood, restricting airflow and causing air to be directed to the other side of the nose. This cycle occurs approximately every 20–30 minutes. Nose bleeds [epitaxis] in the inferior concha are common in this region.
- The olfactory segment is lined with a specialized type of pseudostratified columnar epithelium, known as olfactory epitheliumOlfactory epitheliumThe olfactory epithelium is a specialized epithelial tissue inside the nasal cavity that is involved in smell. In humans, it measures about 1 square centimetre and lies on the roof of the nasal cavity about 7 cm above and behind the nostrils...
, which contains receptors for the sense of the smell. This segment is located along the dorsal roof of the nasal cavity. 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 cruciform plate. 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 dogDog
The domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...
s, the capillary
Capillary
Capillaries are the smallest of a body's blood vessels and are parts of the microcirculation. They are only 1 cell thick. These microvessels, measuring 5-10 μm in diameter, connect arterioles and venules, and enable the exchange of water, oxygen, carbon dioxide, and many other nutrient and waste...
beds flowing through the nasal cavity help cool the blood flow to the brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
.
Blood supply comes from branches of both the internal
Internal carotid artery
In human anatomy, the internal carotid arteries are two major arteries, one on each side of the head and neck. They arise from the common carotid arteries where these bifurcate into the internal and external carotid artery, and they supply the brain....
and external carotid artery
External carotid artery
In human anatomy, the external carotid artery is a major artery of the head and neck. It arises from the common carotid artery when it bifurcates into the external and internal carotid artery.-Course:...
, including branches of the facial artery
Facial artery
The facial artery is a branch of the external carotid artery that supplies structures of the superficial face.-Structure:...
and maxillary artery. The named arteries of the nose are:
- Sphenopalatine and Greater palatine arteries , branches of the maxillary artery.
- Anterior ethmoidal arteryAnterior ethmoidal arteryThe anterior ethmoidal artery, also anterior ethmoid artery is an artery of the head.-Course:Once branching from the ophthalmic artery, it accompanies the nasociliary nerve through the anterior ethmoidal canal to supply the anterior and middle ethmoidal cells, frontal sinus, and anterosuperior...
, a branch of the ophthalmic arteryOphthalmic arteryThe ophthalmic artery is the first branch of the internal carotid artery distal to the cavernous sinus. Branches of the OA supply all the structures in the orbit as well as some structures in the nose, face and meninges... - Branches of facial arteryFacial arteryThe facial artery is a branch of the external carotid artery that supplies structures of the superficial face.-Structure:...
supplying the vestibule of the nasal cavity.
Innervation
Innervation of the nasal cavity responsible for the sense of smell is via the olfactory nerveOlfactory nerve
The olfactory nerve, or cranial nerve I, is the first of twelve cranial nerves. It is instrumental in the sense of smell. Derived from the embryonic nasal placode, the olfactory nerve is capable of regeneration.-Anatomy:...
, which sends microscopic fibers from the olfactory bulb
Olfactory bulb
The olfactory bulb is a structure of the vertebrate forebrain involved in olfaction, the perception of odors.-Anatomy:In most vertebrates, the olfactory bulb is the most rostral part of the brain. In humans, however, the olfactory bulb is on the inferior side of the brain...
through the cribiform plate to reach the top of the nasal cavity.
General sensory innervation is by branches of the trigeminal nerve
Trigeminal nerve
The trigeminal nerve contains both sensory and motor fibres. It is responsible for sensation in the face and certain motor functions such as biting, chewing, and swallowing. Sensory information from the face and body is processed by parallel pathways in the central nervous system...
(V1 & V2):
- Nasociliary nerveNasociliary nerveThe nasociliary nerve is a branch of the ophthalmic nerve. It is intermediate in size between the two other main branches of the ophthalmic nerve, the frontal nerve and the lacrimal nerve, and is more deeply placed.-Path:...
(V1) - Nasopalatine nerveNasopalatine nerveOne branch of the posterior superior nasal branches , longer and larger than the others, is named the nasopalatine nerve ....
(V2) - Posterior nasal branches of Maxillary nerve (V2)
There are two passages in the nasal cavity, not to be confused with nostrils.The entire nasal cavity is innervated by autonomic fibers. Sympathetic
Sympathetic nervous system
The sympathetic nervous system is one of the three parts of the autonomic nervous system, along with the enteric and parasympathetic systems. Its general action is to mobilize the body's nervous system fight-or-flight response...
innervation to the blood vessels of the mucosa causes them to constrict
Vasoconstriction
Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, particularly the large arteries, small arterioles and veins. The process is the opposite of vasodilation, the widening of blood vessels. The process is particularly important in...
, while the control of secretion by the mucous glands is carried on postganglionic parasympathetic nerve fibers originating from the facial nerve
Facial nerve
The facial nerve is the seventh of twelve paired cranial nerves. It emerges from the brainstem between the pons and the medulla, and controls the muscles of facial expression, and functions in the conveyance of taste sensations from the anterior two-thirds of the tongue and oral cavity...
.
Diseases
Diseases of the nasal cavity include viralVirus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
, bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
l and fungal
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
infections, nasal cavity tumors, both benign and much more often malign, as well as inflammations of the nasal mucosa.
External links
- Gross anatomy dissection of the nasal cavity, video http://anatomy.med.umich.edu/nervous_system/ear_vid_D720.html and http://www.anatomy.wisc.edu/courses/gross