The human nose is a complex organ that serves as the primary gateway for the respiratory system and houses the sense of smell. It is divided internally into two passages by the nasal septum.
Anatomy
External Structure: The visible part of the nose is supported by bone (the nasal bone) at the top and flexible cartilage at the bottom, which forms the nostrils (nares).
Turbinates (Conchae): Three pairs of scroll-shaped bones (superior, middle, and inferior) project into the nasal cavity. These structures increase the surface area and create turbulence in the inhaled air.
Paranasal Sinuses: These are air-filled, mucous-lined cavities within the facial bones (frontal, ethmoid, sphenoid, and maxillary) that connect to the nasal cavity.
Primary Functions
The nose performs three essential functions for the body:
1. Respiration (Filtering and Conditioning Air)
The nose acts as an air conditioner and filter for inhaled air before it reaches the sensitive lungs:
Warming: Blood circulating near the surface of the turbinates warms the incoming air to body temperature.
Humidifying: The mucous lining adds moisture to the air.
Filtering: Hairs in the nostrils (vibrissae) and sticky mucus trap dust, pollen, bacteria, and other foreign particles. Tiny hair-like projections called cilia then sweep the contaminated mucus towards the throat to be swallowed or expelled.
2. Olfaction (Sense of Smell)
The sense of smell, or olfaction, is the nose's unique sensory function:
Airborne odor molecules dissolve in the mucus of the olfactory epithelium.
They bind to the olfactory receptor cells, which fire electrical signals up the olfactory nerve (Cranial Nerve I).
The signals are transmitted directly to the olfactory bulb in the brain, and from there to the limbic system (explaining the strong link between smell, memory, and emotion) and the olfactory cortex for conscious interpretation.
3. Voice Resonance
The nasal cavity and the connected paranasal sinuses act as resonating chambers, affecting the unique sound quality and tone of a person's voice.
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Diagram of the Human Nose The external human nose, composed of bone and cartilage, is the most prominent feature of the face in humans. The internal human nose is a hollow structure above the roof of the mouth, divided by the septum into two nasal cavities that extend from the nostrils to the pharynx.
The mucous membrane that lines the nasal cavities is covered with fine hairs known as cilia that help to filter dust and impurities from the air before it reaches the lungs; the air is also moistened as it passes over the sticky nasal membrane.
In the human nose, there are three horizontal folds on the walls of the nasal cavities, called the conchae: other mammals may have more conchae.
The uppermost concha is densely supplied with capillaries that warm the air passing over them to near body temperature.
High in the nasal cavity is a small tract of mucous membrane containing the nerve cell endings of the olfactory nerve, which impart the sense of smell.
Therefore, inflammation of the nasal mucous membranes, which commonly accompanies colds and other infections, not only obstructs breathing but also impairs the sense of smell.
The human nose is much more than a facial feature—it is a highly specialized organ central to respiration, olfaction (sense of smell), immune defense, and speech resonance. Its complex structure and physiological roles make it essential for overall health and well-being.
This guide explores the anatomy, functions, and clinical significance of the human nose.
Blood supply: Branches from sphenopalatine, facial, and ophthalmic arteries.
Innervation: Trigeminal nerve for sensation; olfactory nerve for smell.
Rich vascularization warms inhaled air and plays a role in nosebleeds (epistaxis).
Functions of the Human Nose
Air Filtration: Traps dust, pollen, and microbes.
Air Conditioning: Warms and humidifies inhaled air.
Olfaction: Detects smells via the olfactory region.
Immune Defense: Mucus and cilia trap and remove pathogens.
Speech Resonance: Nasal cavity acts as a sound chamber.
Clinical Significance
Common conditions affecting the nose include:
Deviated septum: Can disrupt airflow and cause snoring or sleep apnea.
Nasal polyps: Obstruct airflow and sinus drainage.
Chronic sinusitis: Inflammation of sinuses causing congestion and pain.
Anosmia: Loss of smell due to damage or infection affecting the olfactory region.
Understanding nasal anatomy is critical for ENT specialists, respiratory therapists, and general healthcare professionals.
Conclusion
The human nose is a multifunctional organ that plays vital roles in breathing, smell, immunity, and communication. Its intricate anatomy and physiology demonstrate the remarkable design of the human body. Maintaining nasal health through proper hygiene, hydration, and medical care is essential for overall well-being.
A diagram illustrating the human nose generally encompasses both its external and internal components. On the outside, it displays the nasal bridge, tip, nares (nostrils), alae (the sides of the nostrils), and columella (the tissue that divides the nostrils). Internally, the nasal cavity is partitioned by the septum and contains turbinates (conchae) and sinuses.
The upper air passages pertain to the respiratory organs located in the human head. These include the nose and throat (pharynx).
When breathing in, air first enters through the nose, where it is initially filtered by a hair-like structure. A bifurcated network of blood vessels within the nasal mucous membrane serves to warm the incoming air. Additionally, mucous droplets from the nasal mucous membrane help to moisten the air.
This process prepares the air for the conditions found within the lungs (pulmo).
The paranasal sinuses (sinus paranasales), which are connected to the nasal cavity, also play a role in this adaptation. From the nose, the air travels to the throat, which comprises various sections, with the esophagus and windpipe intersecting in the medial throat (mesopharynx). The inhaled air continues through the throat to the larynx (larynx) and then to the lower air passages.
In contrast to the sense of taste, the sense of smell is capable of distinguishing a far greater variety of sensations. The qualitative categorization seen in taste (bitter, sweet, sour, salty) does not apply as straightforwardly to smell. Instead, scent classes are utilized to convey the experience (pungent, sweaty, rotten, etc.). The sensory receptors of the olfactory organ (organum olfactus) are situated at the beginning of the respiratory tracts and are approximately the size of a dime, located on the upper nasal wall and the septum. Due to pigmentation, the olfactory region appears yellow, which contrasts with the red membrane. It remains uncertain whether this pigmentation plays a role in the sense of smell. However, it is noted that animals lacking pigmentation (albinos) do not possess a sense of smell.
The tissue within the olfactory region, containing over 10 million receptor cells, is approximately 50 µm thicker than the epithelium of the respiratory tracts.
The olfactory cells feature very fine hairs (cilia), with up to 12 per cell, and are coated in mucus. Nerve processes from the olfactory cells bundle together as fibers leading to the anterior section of the olfactory cortex at the base of the frontal brain.
The olfactory cells are separated from the olfactory cortex by a very thin bone known as the sieve.. The olfactory cells are separated from the olfactory cortex by very thin bone, the sieve, through which the nerve fibers pass through small openings.
After appropriate processing of the olfactory information, the smell becomes known.
Olfactory cells are chemical receptors, i.e. the stimulus of the olfactory cells is the result of a chemical process on the surface of the hairs. How the molecular reaction occurs, with which hundreds of different smells are distinguished, is unclear. Gaseous substances are easier to smell. A water-soluble property increases the ability to smell because the smell molecules enter the air through evaporation.
The human nose is a remarkably complex organ that serves as the primary passage for air, a sensory organ for smell, and an important part of the immune defense system. Its structure is carefully designed to support breathing, olfaction, and speech. Understanding the nose’s anatomy is essential for anyone interested in health, medicine, or physiology.
External Nose: The Visible Framework
The external nose is the part of the nose you see on the face. It consists of:
Nasal bones: Form the upper bridge of the nose.
Cartilaginous structures: Include lateral, septal, and alar cartilages that shape the tip and nostrils.
Nostrils (nares): Two openings that allow air entry.
Function:
The external nose guides airflow into the nasal cavity, supports facial structure, and provides an aesthetic appearance. Its shape also influences air resistance, which is important for effective respiration.
Internal Nose: The Nasal Cavity
The nasal cavity extends from the nostrils to the nasopharynx and is separated by the nasal septum into two symmetrical chambers.
Key Components:
Nasal Septum:
Composed of bone (vomer and perpendicular plate of the ethmoid) and cartilage.
Divides the nasal cavity and supports airflow regulation.
Mucous Membrane:
Lines the nasal cavity.
Contains cilia to move mucus and trapped particles toward the throat.
Produces mucus to trap dust, allergens, and pathogens.
Vestibule:
The front portion of the nasal cavity.
Lined with hair (vibrissae) that filters large particles.
Nasal Conchae (Turbinates)
The turbinates are curved bony structures on the lateral walls of the nasal cavity:
Inferior turbinate
Middle turbinate
Superior turbinate
Functions:
Increase surface area for air contact.
Create turbulence to warm, humidify, and filter air.
Enhance the effectiveness of the olfactory region.
Olfactory Region
Located in the upper part of the nasal cavity, this area contains olfactory epithelium with:
Olfactory receptor neurons: Detect smell.
Supporting cells: Maintain structure and function.
Basal cells: Regenerate olfactory neurons.
Function:
The olfactory region allows humans to detect and distinguish odors, linking smell to memory and emotion through the olfactory nerve.
Paranasal Sinuses
The paranasal sinuses are air-filled cavities surrounding the nasal cavity:
Frontal sinuses
Maxillary sinuses
Ethmoid sinuses
Sphenoid sinuses
Functions:
Reduce skull weight
Produce mucus for trapping pathogens
Act as resonating chambers for speech
Blood Supply and Innervation
Blood supply: From branches of the sphenopalatine, facial, and ophthalmic arteries.
Nerves: Trigeminal nerve for sensation; olfactory nerve for smell.
The rich vascular network helps warm inhaled air and can contribute to nosebleeds (epistaxis).
Functional Significance of Nasal Structure
The nose’s structure enables multiple essential functions:
Air filtration: Traps dust, pollen, and pathogens.
Air conditioning: Warms and humidifies inhaled air.
Olfaction: Smell detection via olfactory region.
Resonance in speech: Nasal cavity acts as a sound chamber.
Immune defense: Mucosa and cilia remove harmful particles.
Clinical Relevance
Understanding nasal anatomy is critical for diagnosing and treating:
Anosmia – loss of smell due to olfactory region damage.
Conclusion
The structure of the nose is a masterclass in biological engineering. Its external and internal frameworks, combined with specialized regions like turbinates and olfactory epithelium, allow it to perform vital functions ranging from respiration and smell to immunity and speech resonance. Maintaining nasal health is crucial for overall respiratory efficiency and sensory well-being.
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The external nose is visible and is pyramidal in shape, with the root located in the upper region and the base located in the lower region. The variance in shape depends on the shape of the ethmoid bone which is an anterior cranial bone located between the eyes. The internal nose is divided into the left and right nasal cavities by the nasal septum. The internal nose also consists of the skin-lined region known as the vestibule and the mucosa-lined region known as the nasal cavity proper.
The nasal framework
The nasal or piriform aperture is situated on the bony skull and represents a bony outline of the nasal cavity, which is the beginning of the respiratory tract. The nasal pyramid is located here with each side consisting of the frontal process of the maxilla and medial to the nasal bone which is linked to the frontal bone.
The nasal cartilage
The front of the nose consists of connective tissue with embedded small pieces of cartilage. This includes the nasal septum and the nasal tip cartilage (lesser alar cartilage and lateral greater alar cartilage). Whatever impression the nose makes as an aesthetically significant element of the face – high, broad, or even crooked – is largely determined by these small cartilages and the cartilaginous portions of the nasal septum. Frequently, the bony portion of the nose is affected by midfacial fractures (e.g., a nasal bone fracture).
A common cause of nasal fractures is blunt trauma. Manual alignment through the application of strong thumb pressure with anesthesia followed by repair may be necessary to prevent lasting misalignments. Injuries that lead to functional impairments may be corrected through nasal surgery or rhinoplasty.
Internal nose
The inner part of the nose is formed by the main nasal cavity which includes the nasal concha, nasal passages (nasal meatus), and paranasal sinus. The nasal septum comprises bone and cartilage in the nose and separates the nasal cavity into two fossae, which are continuations of the nostrils and jointly form their medial border. The nasal septum consists of four structures:
Clinically, deviations of the nasal septum occur quite frequently. These deviations may be present at birth or may result from an accident. A deviated nasal septum can lead to nasal congestion and breathing difficulties which may require surgical correction. Structure of the Nose .
The human nose is more than a facial feature—it is a complex organ integral to respiration, smell, immunity, and speech. Its intricate anatomy allows the body to filter, warm, and humidify inhaled air while protecting the lungs from pathogens and irritants. Understanding nasal anatomy is key to appreciating how this remarkable organ supports overall health.
This comprehensive guide explores the structure of the nose, its functional regions, and clinical relevance.
External Nose: The Visible Gateway
The external nose forms the most recognizable part of the face and serves as the primary entrance for air.
Anosmia (loss of smell): Often related to olfactory region damage or infection.
Proper nasal function ensures efficient breathing, optimal oxygen uptake, and immune defense.
The Nasal Cycle: An Anatomical Curiosity
The nasal cycle is a physiological alternation in congestion and decongestion between nostrils every few hours. Purpose:
Allows mucosa recovery.
Maintains airway efficiency.
This subtle anatomical feature is normal and supports overall nasal health.
Conclusion
Understanding nasal anatomy is fundamental for appreciating how this small but complex organ impacts respiratory health, sensory perception, and overall well-being. From filtering and conditioning air to detecting odors and supporting speech, the nose is a marvel of anatomical design.
Maintaining nasal health through hygiene, proper hydration, and prompt treatment of infections helps preserve its critical physiological functions.
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A lot happens under the surface of the nose. The bone and cartilage under the skin give the nose most of its size and shape. Other structures inside and behind the nose help you breathe. Learning the anatomy of the nose can help you better understand how the nose works.
Bone.
This supports the bridge of the nose. The upper cartilage supports the side of the nose. The lower cartilage adds support, width, and height. It helps shape the nostrils and the tip of the nose.
Skin.
This also helps shape the nose.
Nasal cavity.
This is a hollow space behind the nose that air flows through.
Septum.
This is a thin wall made of cartilage and bone. It divides the inside of the nose into 2 parts.
Mucous membrane.
This is thin tissue that lines the nose, sinuses, and throat. It warms and moistens the air you breathe in. It also makes the sticky mucus that helps clean the air of dust and other small particles.
Turbinates.
These are curved, bony ridges on each side of the nose. They are lined with mucous membrane. They warm and moisten the air you breathe in.
Sinuses.
These are hollow, air-filled chambers in the bone around your nose. Mucus from the sinuses drains into the nasal cavity.
The human nose is far more than a simple airway for breathing. It is a complex, highly specialized organ responsible for respiration, olfaction (smell), immune defense, and speech resonance. Its intricate physiology allows the body to filter, warm, humidify, and analyze the air we breathe—while simultaneously protecting the lower respiratory tract from pathogens and irritants.
This article explores the anatomy and physiology of the human nose, how it functions in health, and why it is vital to overall respiratory and neurological well-being.
Overview: What Is the Human Nose?
Physiologically, the nose is the primary entrance to the respiratory system and the sensory organ for smell. It works continuously to:
Mouth breathing bypasses these benefits and may negatively affect long-term health.
Conclusion
The physiology of the human nose reflects a remarkable balance of structure, function, and defense. Far beyond its role in breathing, the nose is a dynamic organ that conditions air, protects the body, enables smell, and contributes to communication and neurological processing.
Maintaining healthy nasal function is essential for optimal respiratory performance and overall well-being.
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THE HUMAN NOSE
Thehuman nosehas several physiologic functions. As
the air is inspired through the nose it is humidified and warmed by passing
over the moist and warm nasal mucosa. The nose is an energy-conscious organ in
that expired air is cooled and some of the moisture is recaptured. The
functions of warming and humidification require a tremendous blood flow to the
nasal mucosa and also place substantial stress on the nasal mucosa. The nose
has what is known as a nasal cycle.
To allow the mucosa time to rest from these
functions, the nose has periods in which one side of the nose becomes swollen,
which we call congestion. During the same period the other side of the nose
remains patent or decongested. The normal nasal cycle lasts from three to six
hours, and during this time first one side of the human nose will be congested
and the other side will be patent; then the second side becomes congested as
the first side becomes patent. It is also normal for the human nose to be
congested when an individual lies down.
Particularly if you lie on your side
you may notice that the downside of your nose becomes congested. Olfaction is
the medical word for smell. Smell is one of the six human senses and for some
individuals is a very important sense; for others it seems to be less
important.
The olfactory centers, as described under the anatomy section,
reside very high along the roof of the nose. In order for these centers to be
stimulated, the odors have to be inspired into the human nose and carried up to
the roof of the human nose. If the odor does not reach the roof of the nose due
to a variety of conditions, the odor will not be perceived. The nose is capable
of distinguishing a large number of different odors. Our understanding of
precisely how this occurs is limited, but increasing.
Taste is a sense very different from olfaction. It is
another of the human senses and is perceived primarily on the tongue. There are
four recognized tastes and these are sweet, salty, sour, and bitter. They
occupy geographically separate areas on the tongue and are perceived in cells
clustered together in taste buds. The sense of smell plays a major role in the
flavor of foods and it is common for individuals who lose their sense of smell
to report that food loses its taste. This is of course incorrect; the food has
only lost its aroma, and taste (sweet, salty, sour, bitter) remains intact.
The nose is the part of the respiratory tract that sits front and center on your face. You use it to breathe air in and to stop and smell the roses. The nose’s exterior anatomy includes the nasal cavity, paranasal sinuses, nerves, blood supply, and lymphatics.
The external part of the nose includes the root (between the eyes), the dorsum that runs down the middle, and the apex at the tip of the nose. Two openings called nostrils (nares) allow air in. They’re divided by the nasal septum (dividing wall of cartilage and bone), and the parts that surround the nostrils are called the alae (ala singular).
The nose has a bony part that’s formed by the bony nasal septum, the nasal bones, and parts of the maxillae, palatine, and frontal bones. The cartilaginous part of the nose is formed by two lateral cartilages, two alar cartilages, and a septal cartilage.
The nasal cavity
The nares serve as the entryway to the nasal cavities, which open posteriorly into the nasopharynx via the choanae. The walls of the nasal cavity include the following features:
Roof: The roof is divided into three parts: frontonasal, ethmoidal, and sphenoidal. Each part corresponds to the underlying bone of the same name.
Floor: The floor consists of the palatine process of the maxilla and the horizontal plate of the palatine bone.
Medial wall: This wall is the nasal septum, which is formed by the perpendicular plate of the ethmoid bone, the vomer, cartilage, and the nasal crests of the maxillary and palatine bones.
Lateral wall: This wall is hallmarked by three nasal conchae (superior, middle, and inferior) that project inferiorly from the wall. They divide the nasal cavity into four passages that have openings to the paranasal sinuses:
The sphenoethmoid recess lies posterior to the superior concha and has the opening for the sphenoidal sinus.
The superior nasal meatus lies between the superior and middle conchae and has openings to the posterior ethmoidal sinuses.
The middle nasal meatus is longer and deeper than the superior nasal meatus. The frontal sinus communicates with the middle nasal meatus via the infundibulum, a passageway that opens into the semilunar hiatus (groove in the ethmoid bone). The maxillary sinus opens into the semilunar hiatus. An ethmoidal bulla (a round swelling formed by the middle ethmoidal cells, or air-filled cavities) is formed just above the semilunar hiatus. The middle and anterior ethmoidal sinuses drain into the middle nasal meatus.
The inferior nasal meatus is found below the inferior nasal concha. The nasolacrimal duct opens into this meatus.
The nasal cavity is lined with nasal mucosa, except for the nasal vestibule, which is lined with skin. The mucosa over the superior one-third of the nasal cavity is the olfactory area. Air is drawn past the specialized mucosal cells called the olfactory epithelium as air is sniffed though the nose.
The olfactory epithelium contains receptors of olfactory neurons that detect smells. Olfactory neurons (from CN I) join together to form nerve bundles that run up through the cribiform plate of the ethmoid bone to the olfactory bulb. The olfactory tract transmits the sensory information about smell from
The paranasal sinuses
The paranasal sinuses are air-filled cavities in the frontal, ethmoid, maxilla, and sphenoid bones. They’re lined with a mucosal membrane and have small openings into the nasal cavity:
Maxillary sinus: This sinus is located in the body of the maxilla behind the cheek just above the roots of the premolar and molar teeth. It’s shaped like a pyramid. It opens into the nasal cavity via the semilunar hiatus.
Frontal sinuses: Found within the frontal bone, each of these sinuses is triangular in shape and runs above the medial end of the eyebrow and backward to the orbit. They open into the nasal cavity via the semilunar hiatus.
Sphenoid sinuses: These sinuses are found in the sphenoid bone. Each opens into the sphenoethmoid recess.
Ethmoid sinuses: The anterior, middle, and posterior ethmoid sinuses are located in the ethmoid bone between the nose and the eye. The anterior sinus opens into the nasal cavity by the infundibulum, the middle sinus opens into the ethmoidal bulla, and the posterior sinus opens into the superior meatus.
Nerves, blood vessels, and lymphatics of the nose
Nerve supply to the external nose is provided by the infratrochlear and external nasal branches of the ophthalmic nerve and the infraorbital branch of the maxillary nerve, both of which are part of the trigeminal nerve (CN V).
The olfactory nerves (CN I) pass through the cribiform plate of the ethmoid bone. General sensory innervation of the nasal cavity and the paranasal sinuses is from the ophthalmic nerve (CN V1) and maxillary nerve (CN V2).
Blood is supplied to the external part of the nose by branches of the ophthalmic and maxillary arteries. The skin of the ala and septum are supplied by the facial artery.
Blood is brought to the walls of the nasal cavity and sinuses by branches of the maxillary artery. The most important is the sphenopalatine artery, which anastomoses with a branch of the superior labial artery. Venous blood is returned from the nasal cavity by veins that accompany the arteries.
Lymph from the nasal cavity drains into the submandibular lymph nodes and vessels that drain into the upper deep cervical lymph nodes. The Anatomy of the Nose Video :
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