Nose Anatomy: Complete Guide with Parts, Names, Functions & Diagram

Overview of Nose Anatomy

The nose is the gateway to the respiratory system. It plays a vital role in our sense of smell, making it a key part of the olfactory system. Its structure is shaped by the nasal bones and cartilage, including the nasal septum, which separates the nostrils and divides the nasal cavity into two distinct chambers. This intricate nose anatomy supports two essential functions: breathing and detecting odors.
The nose has both external and internal components. The external nose, aside from its aesthetic importance, protects the internal structures and allows air to enter. The internal part, known as the nasal cavity, plays a multifaceted role in respiration, olfaction, speech, and even taste perception. This dual-purpose organ is an incredible example of how our body combines form and function.

This page explores the anatomy of the nose, with the structure of the nasal cavity, highlighting its unique features and their importance in functions like breathing, filtration, and smell.

Function of the Nose

• The nose plays a vital role in breathing.
• The nasal cavity and nearby sinuses are lined with nasal mucosa, which warms and moistens inhaled air.
• Shell-like bones called nasal conchae assist in the air-warming process.
• Tiny hairs in the nostrils trap large particles, preventing them from entering the lungs.
• The nose triggers sneezing to expel irritating particles.
• The sense of smell (olfaction) is controlled by smell-detecting cells in the upper nasal cavity.
• The nose aids speech production, particularly nasal vowels and consonants, by directing airflow.
• Sinuses act as echo chambers, amplifying sounds during speech.

Nose Anatomy Diagram

Nose Anatomy

External Nose Anatomy

The external nose is a noticeable feature on the face that leads to the nasal cavity. It helps us breathe, and smell and adds to our facial appearance. This article looks at the structure of the external nose anatomy, focusing on its bones and the muscles connected to it.

A – Skeletal Framework

The external nose is a structure supported by both bones and cartilage:

Bones

It is located in the upper part of the nose. This framework consists of the nasal bones, parts of the maxillae, and the frontal bone.

1. Nasal Bones

The nasal bone is a small, flat bone that forms part of the facial skeleton. Along with other bones like the zygomatic, maxilla, palatine, lacrimal, vomer, inferior nasal conchae, and mandible, it helps shape the face.

Location and Shape

The nasal bones are paired and lie on either side of the midline, between the frontal processes of the maxilla. These rectangular bones have two surfaces (external and internal) and four borders. Together, they form the bridge of the nose at the top, while their lower edges connect to the nasal cartilage, shaping the upper boundary of the nasal cavity.

Structure

• External Surface: Slightly curved outward and covered by small muscles like the procerus and nasalis.
• Internal Surface: Curved inward with a groove for the anterior ethmoidal nerve.

The nasal bones join with nearby bones through various connections:

• Top Border: Joins the frontal bone at the frontonasal suture.
• Sides: Connect to the maxilla at the nasomaxillary suture.
• Bottom Border: Attaches to the lateral cartilage of the nose.
• Inner Edge: Links the two nasal bones at the internasal suture and extends backward to contribute to the nasal septum.

Function

The nasal bones support the structure of the nose, form the upper part of the nasal opening, and protect the nasal cavity from injury.

2. Frontal Process of Maxilla

The frontal process of the maxilla is a slender, upward extension located on the front-upper part of the maxilla. It connects seamlessly with the maxilla’s main body below and serves several structural and functional roles:

• It forms the anterior lacrimal crest and the ethmoidal crest.
• It plays a key role in shaping the lateral wall of the nasal cavity.

Articulations of the Frontal Process:

• Anteriorly: Joins the nasal bone’s lateral edge, forming the nasomaxillary suture.
• Superiorly: Meets the frontal bone’s nasal margin, creating the front maxillary suture.
• Posteriorly: Connects with the lacrimal bone, contributing to the lacrimomaxillary suture.
• Medially: Interfaces with the middle nasal concha of the ethmoid bone.

This structure integrates with neighboring bones to support and stabilize the nasal and orbital regions, underscoring its importance in facial anatomy.

3. Nasal Part of Frontal Bone

The nasal part of the frontal bone is a small section located toward the lower middle region. It connects:

• Laterally with the orbital parts.
• Superiorly with the squamous part.

This structure includes the nasal spine and nasal notch of the frontal bone. It plays a key role in shaping the root of the nose, the bony nasal septum, and the roof of the nasal cavities.

The nasal part forms important joints with neighboring bones:

• Inferomedially: It connects with the upper edges of the right and left nasal bones to form the frontonasal suture.
• Inferolaterally: It joins the frontal processes of the right and left maxillae, creating the frontomaxillary sutures.
• Posteroinferiorly: It articulates with the upper portion of the ethmoid bone, forming the frontoethmoidal suture.

These connections contribute to the stability and framework of the nasal region.

Cartilages

Five distinct cartilages play a crucial role in supporting and shaping this area. It is found in the lower portion, it includes two lateral cartilages, two alar cartilages, and one septal cartilage. Additionally, smaller alar cartilages provide further support.

1. Septal Cartilage

The septal nasal cartilage is a thin, quadrilateral structure of hyaline cartilage that divides the nasal cavity into two separate chambers.

It is positioned between the perpendicular plate of the ethmoid bone and the vomer bone, encased by a protective mucous membrane. The upper edge of this cartilage connects to the nasal bones, while its lower edge joins to the alar cartilage through fibrous tissue.

This division into two nasal cavities helps streamline airflow. It creates turbulence in the narrow passages, which enhances the efficiency of air movement in both directions.

Additionally, the septal nasal cartilage is crucial in shaping and aligning the nose, serving as its central structural support.

2. Lateral Nasal Cartilage

The lateral nasal cartilage is a wing-shaped structure that extends outward from the septal nasal cartilage. It sits just below the nasal bones and above the major alar cartilage, with a small gap between them.

These cartilages work together, with the lateral nasal cartilage and major alar cartilage curving to form a sturdy connection, supported by fibrous tissue.

It is made of strong yet flexible hyaline cartilage (the same type as the septal nasal cartilage), the lateral nasal cartilage connects to the septum at its upper part.

This connection helps maintain the structure of the nasal cavities. If the cartilage weakens or collapses, it can obstruct the inner nasal valve, reducing airflow and making it harder to breathe.

3. Major Alar Cartilage

The major alar cartilage is located on either side of the nasal tip. It plays a vital role in shaping the nose and supporting airflow. These thin, hyaline cartilage structures are connected to the lateral nasal cartilage by fibrous tissue. They are folded into two distinct parts: the medial crus and the lateral crus.

1. The medial crus forms the inner section and aligns perpendicularly with the septal nasal cartilage.
2. The lateral crus constitutes the outer portion, shaping the ala (the flared portion) of the nose.

Together, the medial and lateral crus create an oval-shaped tip at each nostril.

At the center of the nasal tip, the two sides of the major alar cartilages meet, forming a small notch called the apex of the nose. These cartilages also help form the walls of the nostrils/nares, ensuring they remain open.

This structural support facilitates efficient airflow through the nasal passages, optimizing respiration by guiding air to the nasal valve.

4. Minor Alar Cartilage

The minor alar cartilages are small, flexible pieces of hyaline cartilage. They are usually three to four on each side of the nose. They sit between the lateral nasal cartilage and the major alar cartilage, forming part of the nostrils’ outer edges (the ala).

Also known as “accessory cartilage,” these tiny structures support and shape the nostril base. Together with the major alar cartilage, they help keep the nostrils stable and functional, maintaining their proper shape and appearance.

5. Vomeronasal Cartilage

The vomeronasal cartilage is a thin piece of hyaline cartilage that joins the vomer bone with the septal nasal cartilage. It is associated with the vomeronasal organ, a component of the accessory olfactory system that detects certain chemical signals.

This organ helps detect scents and has a lining similar to the main smelling area in the nose. The vomeronasal cartilage provides structural support, contributing to the stability and function of the nose.

B. External Openings

The external openings or nostrils, also called anterior nasal apertures, are the two pear-shaped openings at the base of the nose.

They serve as the entry points for air into the nasal cavity, playing a vital role in breathing and filtering particles from the air before it reaches the lungs.

Nostrils (Nares)

A nostril is one of the two openings in the nose that allow air and other gases to flow in and out of the nasal passages. In humans, the nostrils take turns becoming slightly swollen and then shrinking in a natural process called the nasal cycle.

The nostrils are separated by a wall of tissue called the septum. If the septum is not straight, it can make one nostril appear larger than the other. In severe cases, damage to the septum can cause the nostrils to merge into a single opening.

Humans, like many other land-dwelling animals, have two external nostrils (at the front of the nose) and two internal nostrils (located at the back of the nasal cavity). These internal nostrils, also called choanae, connect the nose to the throat, making breathing possible.

Each nostril contains about 1,000 tiny hairs that trap dust, pollen, and other particles to keep the airways clean.

Interestingly, the brain can process different smells from each nostril, similar to how the eyes process different images, which can lead to a unique “smell rivalry” experience.

C. Skin and Soft Tissue

The skin on the nose changes in thickness along its length. At the top, near the glabella (between the eyebrows) and down to the nasofrontal angle (where the nose starts to slope), the skin is thick, flexible, and mobile.

As it reaches the bridge of the nose, the skin becomes thinner and less flexible because it is close to the underlying bone. From the bridge to the tip of the nose, the skin remains thin. At the tip, however, the skin thickens again and contains many large oil-producing glands.

Beneath the skin, four layers are separating it from the bones and cartilage. These layers include:

1. A superficial fatty layer.
2. A fibromuscular layer connects to the facial muscles.
3. A deeper fatty layer.
4. The periosteum is a layer covering the bones.

Some soft tissue areas of the nose lack cartilage support. These include regions near the sides of the septum (paraseptal area), around the lateral cartilages, the top of the nostrils, and the alae (the sides of the nostrils).

D. Muscles

The muscles of the nose are part of the facial muscle group and play a role in breathing and facial expressions.

These muscles include the procerus, nasalis, depressor septi nasi, levator labii superioris alaeque nasi, and a portion of the orbicularis oris (which is mainly a muscle of the mouth). Like all facial muscles, the nose muscles are controlled by the facial nerve and its branches.

Superficial Muscular Aponeurotic System (SMAS)

Each muscle works independently and is interconnected through a layer of tissue called the superficial muscular aponeurotic system (SMAS). This system extends from the upper part of the nose (nasofrontal area) to the tip of the nose.

At the nasal valve, the SMAS divides into two layers: a superficial layer and a deeper layer, with each layer further dividing into medial (center) and lateral (side) components. This connection allows the muscles to work together efficiently.

1. Procerus

The procerus muscle, located over the bridge of the nose, plays a key role in creating wrinkles in this area. It becomes active during expressions of concentration or frowning.

2. Nasalis

The nasalis muscle is composed of two distinct sections: the transverse compressor naris and the alar dilator naris.

• The compressor naris is responsible for narrowing and, in some cases, completely closing the nostrils.
• The dilator naris includes the larger posterior and smaller anterior portions and functions to flare the nostrils.

This action enhances airflow and contributes to shaping the upper ridge of the philtrum. Additionally, the dilator naris supports the nasal valves, playing a structural role in maintaining their form and function.

3. Depressor Septi Nasi

The depressor septi nasi muscle plays a key role in nasal function. Its primary job is to pull the nasal septum, columella, and nose tip downward.

At the start of inhalation, this muscle contracts to stabilize the nasal septum. It works alongside the dilator naris muscle to expand the nostrils, making breathing easier.

4. Levator Labii Superioris Alaeque Nasi

The levator labii superioris alaeque nasi muscle splits into two parts: a medial part and a lateral part.

• The medial part connects to the cartilage of the nose (major alar cartilage) and the skin above it.
• The lateral part merges with the muscles of the upper lip, specifically the levator labii superioris and the orbicularis oris.

The lateral part helps lift the upper lip and makes the curve above the nasolabial fold more pronounced. The medial part pulls the side of the nostrils upward, changes the curve near the nostrils, and helps widen them.

Internal Nose Anatomy

The internal nose anatomy consists of the nasal septum, turbinates, paranasal sinuses, and other supportive parts. These work together to clean and humidify the air, adjust its temperature, and produce mucus to catch dust, allergens, and germs.

This system ensures that the air reaching the lungs is clean, moist, and warm, helping you breathe easily and keeping your respiratory system safe.

A. Nasal Septum

The nasal septum is a thin wall inside the nose that separates the nasal cavity into left and right sides, creating two nostrils.

At the front, the visible part called the columella nasi is made of soft tissue and cartilage. The septum itself is about 2 mm thick and is built from a mix of bone and cartilage.

The nasal septum has four main parts: Maxillary crest, Perpendicular plate of the ethmoid bone, Septal cartilage, Vomer bone.

At the bottom, the maxillary crest connects the septum to the maxilla (upper jawbone) and the palatine bones. This connection helps secure the septal cartilage at the front and the vomer bone at the back, giving the nasal septum its stability and structure.

1. Maxillary Bone (the Crest)

The maxilla, or upper jawbone, is a key structure of the facial skeleton (viscerocranium). It contributes to the formation of the eye socket (orbit), nasal cavity, and palate, while also anchoring the upper teeth. This bone is essential for chewing, speaking, and facial support.

The maxilla has a central body and four bony extensions called processes: frontal, zygomatic, palatine, and alveolar.

It connects with multiple skull bones and fuses with its counterpart on the opposite side through the intermaxillary suture, ensuring facial symmetry and stability.

2. Perpendicular Plate of Ethmoid Bone

The perpendicular plate of the ethmoid bone is also called the vertical plate. It is a thin, flat structure with a polygon-like shape. It extends downward from the cribriform plate and helps form the nasal septum, which divides the nose into two sides. This plate is often slightly curved to one side.

1. At the front, the perpendicular plate connects to the spine of the frontal bone and the crest of the nasal bones.
2. At the back, it has two parts: the upper part joins the sphenoidal crest, while the lower part connects to the vomer bone.
3. The bottom edge is thicker than the back edge and supports the septal nasal cartilage, a key part of the nose’s structure.

Most of the plate’s surface is smooth, but near the top, there are small grooves and canals. These connect to tiny openings in the cribriform plate and carry small branches of the olfactory nerves, which are crucial for the sense of smell.

3. Septal Nasal Cartilage (Quandrangular Cartilage)

The septal nasal cartilage, also known as the cartilage of the septum or quadrangular cartilage, is made of hyaline cartilage. It is shaped like a broad quadrilateral, thicker at the edges than its center. It also helps separate the nasal cavities at the front.

The anterior margin, which is thickest near the top, connects to the nasal bones and merges with the front edges of the lateral nasal cartilages. Its lower part attaches to the medial crura of the major alar cartilage through fibrous tissue.

The posterior edge of this cartilage links to the perpendicular plate of the ethmoid bone, while the lower edge connects to the vomer bone and the palatine processes of the maxilla.

4. Vomer Bone

The vomer is a single, unpaired facial bone situated along the midline of the skull. It plays a key role in forming the lower portion of the nasal septum, while the upper part is shaped by the perpendicular plate of the ethmoid bone.

This bone has a thin, somewhat rectangular structure and features two surfaces and four distinct edges. Its surfaces are etched with fine grooves that accommodate blood vessels.

A notable feature on each surface is the nasopalatine groove, which slants downward and forward, providing a pathway for the nasopalatine nerve and associated blood vessels.

The vomer also connects to several other skull bones, including the sphenoid, ethmoid, left and right palatine bones, and the left and right maxillae.

This arrangement highlights its structural importance in stabilizing the nasal septum and facilitating proper airflow within the nasal cavity.

B. Roof Bones

The ethmoid bone and the maxilla are the primary bones that create the roof of the nasal cavity.

1. Cribriform Plate of Ethmoid Bone

The cribriform plate, also known as the horizontal lamina, is a delicate, spongy structure forming part of the ethmoid bone.

It plays a crucial role in supporting the olfactory bulb and is perforated with numerous small openings called olfactory foramina. These foramina allow the olfactory nerves to pass through, connecting the nasal cavity to the brain for the perception of smell.

The anterior edge of the cribriform plate is short, thick, and articulates with the frontal bone. Two small wing-like projections, or alae, extend from its front, fitting into depressions in the frontal bone to complete the foramen cecum.

The sides of the cribriform plate are typically smooth, though they may bulge slightly due to the presence of a small air sinus within.

At its medial groove, foramina enables nerve pathways to the upper portion of the nasal septum. In contrast, the foramina along its lateral regions transmit nerves to the superior nasal concha. It ensures the functional connection of the olfactory system with different parts of the nasal cavity.

2. Sphenoid Bone

The sphenoid bone is among the most intricate structures in the human body. Its unique shape has earned it the nickname “wasp bone.” It is positioned at the center of the skull’s base and forms a significant part of the floor of the middle cranial fossa.

This bone plays a critical role in supporting and protecting vital soft tissues, including cranial nerves and portions of the brain. It is perforated by various openings, known as foramina and canals.

It acts as a pathways for blood vessels and nerves to pass between the brain and other parts of the body. The sphenoid bone’s strategic position and structural complexity make it essential for the proper functioning of the nervous and vascular systems.

C. Floor

1. Palatine Process of Maxilla

The palatine process of the maxilla is a sturdy, flat bone that extends horizontally from the inner side of the maxilla. It joins with its counterpart on the opposite side at the median palatine suture, which forms a raised ridge known as the nasal crest. This crest supports the lower edge of the vomer bone.

Along with the horizontal plate of the palatine bone and the palatine process of the incisive bone, it creates the hard palate. It is a vital structure separating the nasal cavity from the oral cavity.

Additionally, it forms the nasal cavity floor, playing a crucial role in dividing these two spaces. As the largest component of the bony palate, it is essential for both breathing and chewing functions.

2. Horizontal Plate of the Palatine Bone

The horizontal part of the palatine bone is a flat, rectangular structure with two main surfaces and four edges:

• Nasal Surface (Top Side): This surface is slightly curved inward and forms the back section of the nasal cavity floor.
• Palatine Surface (Bottom Side): It makes up the back quarter of the hard palate. It has a slightly rough and concave texture. At its back edge, there may be a small ridge where the Tensor veli palatini muscle attaches.
• Front Edge: It is rough and notched to connect with the palatine process of the maxilla.
• Back Edge: It is curved and free, supporting the soft palate. At its inner end, there is a small sharp projection called the posterior nasal spine, which anchors the Musculus uvulæ.
• Side Edge: It is joined to the lower edge of the perpendicular part of the bone and has a groove for the pterygopalatine canal.
• Inner Edge: It is thick and serrated for joining with the matching bone on the other side. When paired, their raised edges form a nasal crest, which supports the vomer bone.

D. Lateral Wall

Conchae (Turbinates)

The nasal cavity contains three types of nasal conchae, which are curved bony structures essential for conditioning the air we breathe:

1. Inferior Nasal Concha: The largest and most prominent of the conchae. This structure is a standalone bone covered by a mucous membrane rich in blood vessels. Its primary role is to humidify and cleanse incoming air, preparing it for smooth passage to the nasopharynx.
2. Middle Nasal Concha: It is situated between the inferior and superior conchae. This part of the ethmoid bone is designed to trap airborne particles and enhance air humidification.
3. Superior Nasal Concha: The smallest concha lies above the middle concha, just beneath the sphenoethmoidal recess. Also a component of the ethmoid bone, it plays a crucial role in filtering and humidifying the air.

Together, these structures ensure that the air entering the respiratory system is clean, moist, and suitable for the delicate tissues of the lungs.

Meatuses

The nasal meatuses are three passageways inside the nasal cavity that help direct airflow and drainage. These include the superior, middle, and inferior meatuses, each located beneath a corresponding nasal concha.

1. Superior Meatus

The superior meatus is the smallest and sits just below the superior nasal concha. Though short and narrow, it plays an important role in nasal function.

At the back, it connects to the sphenopalatine foramen, an opening that links the nasal cavity to deeper structures. It also serves as the drainage site for the posterior ethmoidal air cells, small air-filled spaces within the ethmoid bone.

2. Middle Meatus

The middle meatus is larger and positioned beneath the middle nasal concha. The hiatus semilunaris has a distinctive curved groove running along its surface.

This groove is framed by two key structures: the uncinate process below and the bulla ethmoidal above. The bulla ethmoidal is a rounded elevation containing the middle ethmoidal air cells, which drain into this region.

This meatus also serves as a major drainage pathway for the frontal sinus, maxillary sinus, and anterior ethmoidal air cells, making it vital for sinus ventilation.

3. Inferior Meatus

The inferior meatus is the largest and extends along the lower part of the nasal cavity, positioned beneath the inferior nasal concha. Unlike the others, it is primarily involved in tear drainage rather than sinus ventilation.

The nasolacrimal duct, which carries tears from the eyes, opens into the front part of this meatus, allowing excess fluid to drain into the nasal cavity.

Each meatus has a unique role in respiration, drainage, and overall nasal function, contributing to efficient airflow and sinus health.

E. Nasal Vestibule

The nasal vestibule is the frontmost part of the nasal cavity and is visible from the outside. It is mostly surrounded by the soft tissue of the nose and shaped by cartilage.

The sides are supported by the greater and lesser alar cartilages, while the middle part is formed by the flexible nasal septum. The upper limit is marked by a ridge called the limen nasi, and the back extends to the skin over the upper jawbone. The bottom opening is the nostril.

The inner surface of the nasal vestibule is covered with a tough, protective layer of skin called keratinized stratified squamous epithelium. This is different from the deeper nasal cavity, which has a special lining called respiratory epithelium.

Inside the vestibule, there are small hairs called vibrissae. These help trap dust and tiny particles from the air before it enters the lungs. The air is further checked for smells by the olfactory bulb, which contains sensory cells located in the upper part of the nasal cavity.

F. Respiratory Region

The respiratory region is the largest part of the nasal cavity and plays a vital role in conditioning the air we breathe. It ensures that incoming air is warm, moist, and clean before it reaches the lungs. This region is lined with specialized tissue that traps harmful particles and produces mucus to keep the respiratory tract clear.

Functions of the Respiratory Region

1. Air Warming: As air passes through, blood vessels in the nasal lining transfer heat, bringing the air to body temperature.
2. Humidity Control: Moisture from mucus and underlying tissues saturates the air, preventing dryness in the lungs.
3. Air Filtration: Tiny hair-like structures (cilia) and sticky mucus capture dust, germs, and allergens, preventing them from entering the respiratory system.
4. Mucus Production: Goblet cells within the respiratory lining continuously produce mucus, which traps contaminants and keeps the nasal passages moist.
5. Mucus Clearance: Cilia in the respiratory epithelium move mucus toward the throat, where it is swallowed or expelled, keeping the airway clean.

Paranasal Sinuses

The paranasal sinuses are hollow, air-filled spaces around the nose. They help make the skull lighter, warm, and moisten the air we breathe, and improve the sound of our voice.

These sinuses are found in both the braincase (neurocranium) and the facial bones (viscerocranium). Three skull bones contain sinuses:

• Frontal bone – positioned above the eyes, forming the forehead.
• Ethmoid bone – a complex structure between the eyes, containing multiple small air cells.
• Sphenoid bone – located deep within the skull, behind the nasal cavity.

The maxilla, the largest facial bone, also has sinuses, making it the only face bone with this feature.

Each pair of sinuses is named after the bone they are in, creating four groups: frontal, ethmoid, sphenoid, and maxillary sinuses. These sinuses play an important role in breathing, voice quality, and keeping the head balanced.

1. Frontal Sinuses

The frontal sinuses are two air-filled spaces in the frontal bone of the skull. They are located above the eyebrows and behind the upper part of the nose. They are the highest of the paranasal sinuses and help lighten the skull while also producing mucus to keep the nose moist.

These sinuses drain through a small passage called the frontonasal duct, which connects to the ethmoidal infundibulum. From there, mucus flows into the middle part of the nasal cavity through an opening called the semilunar hiatus.

Interestingly, these sinuses are not fully developed in young children and usually become noticeable after the age of 7.

Nerve signals from the frontal sinuses travel through the supraorbital nerve, which is a branch of the ophthalmic nerve (CN V1). Blood supply comes from the anterior ethmoidal artery, a branch of the ophthalmic artery.

2. Maxillary Sinuses

The maxillary sinuses are the largest air-filled spaces in the face. It is located in the upper jaw (maxilla) on both sides of the nose. They help make the skull lighter and play a role in how our voice sounds.

These sinuses drain mucus through small openings called maxillary ostia, which connect to the middle part of the nasal cavity. Like the frontal sinuses, they drain through a curved groove in the nasal wall called the semilunar hiatus.

The maxillary sinuses receive nerve signals through branches of the maxillary nerve (CN V2), specifically the anterior, middle, and posterior superior alveolar nerves.

Blood supply comes from the superior alveolar branches of the maxillary artery, providing oxygen and nutrients to the sinus tissues.

3. Ethmoidal Sinuses

The ethmoid sinuses, also called ethmoid air cells, are one of four pairs of paranasal sinuses in the human skull. Unlike other sinuses, which have one or two large hollow spaces, the ethmoid sinuses consist of multiple small, air-filled compartments.

These tiny chambers are embedded within the ethmoid bone, a delicate structure located between the eyes and behind the nasal bridge. Their number and size can vary from person to person.

These sinuses are grouped into three sections: anterior (front), middle, and posterior (back). Each section drains into different parts of the nasal cavity, with all eventually connecting to either the superior or middle nasal meatus.

Their primary role is to filter, warm, and humidify inhaled air while also contributing to the overall structure and function of the nasal passages.

4. Sphenoidal Sinuses

The sphenoidal sinuses are air-filled spaces within the sphenoid bone. It is positioned behind the nasal cavity. Their size and shape can vary, sometimes extending into the bone’s wings.

Unlike other paired sinuses, they are asymmetrical due to an irregular bony septum that divides them unevenly. These sinuses drain into the sphenoethmoidal recess, a small space located above and behind the superior nasal concha.

These sinuses are positioned close to several important brain structures, including:

1. The optic nerves and optic chiasm (which help with vision)
2. The pituitary gland (which controls hormones)
3. The internal carotid arteries (which supply blood to the brain)
4. The cavernous sinuses (which help drain blood from the brain).

Their sensory innervation comes from the posterior ethmoidal nerves, which are branches of the ophthalmic division of the trigeminal nerve (CN V1). Blood supply is provided by the posterior ethmoidal arteries, stemming from the ophthalmic artery.

Blood Supply

The nose has a rich blood supply from three main arteries: the ophthalmic artery, maxillary artery, and facial artery. These arteries originate from the carotid arteries and form a complex network beneath the nasal lining, ensuring oxygen and nutrients reach nasal tissues.

1. Ophthalmic Artery Contributions

• Anterior and posterior ethmoidal arteries: Supply the upper nasal septum, nasal roof, and nearby sinuses, including the ethmoid and frontal sinuses.
• Dorsal nasal artery: Delivers blood to the skin over the bridge and sides of the nose.

2. Maxillary Artery Contributions

• Sphenopalatine artery: It is the primary artery nourishing the inner nasal lining.
• Greater palatine artery: Supports blood flow to the hard palate and nearby nasal structures.
• Posterior lateral nasal arteries & posterior septal branches: Provide circulation to the nasal walls and septum.
• Infraorbital artery (with superior anterior and posterior alveolar branches): Extends blood flow to adjacent facial regions.

3. Facial Artery Contributions

• Superior labial artery: It supplies additional blood to the nose.
• Lateral nasal and septal branches: Maintain circulation to the nostrils and surrounding skin.

This intricate blood supply ensures nasal tissues remain well-nourished, promoting quick healing. However, the high vascular density also makes the nose prone to bleeding when blood vessels are damaged.

Venous Drainage

The veins of the nose play a crucial role in draining blood from different regions. The angular vein is responsible for draining the sides of the nose and receives blood from the lateral nasal veins, which extend from the nostrils (alae). This vein connects with the superior labial vein, facilitating venous return.

At the upper part of the nose, small veins from the dorsum merge into the nasal arch. It is a branch of the frontal vein, which helps drain blood from the root of the nose.

Woodruff’s plexus is a network of large, thin-walled veins present deeper inside the nasal cavity near the back of the inferior meatus. These veins are large, thin-walled, and have little surrounding tissue, like muscle or fibers. The mucous membrane covering them is also thin and has very few structures.

Lymphatic Drainage

The lymphatic system of the nose follows a clear drainage pattern. The surface lymphatic vessels run alongside veins, while the deeper ones follow arteries.

• The front part of the nasal cavity, including its walls, drains lymph and external nasal skin into the submandibular lymph nodes.
• The deeper parts of the nasal cavity and the paranasal sinuses drain into the upper deep cervical lymph nodes, either directly or via the retropharyngeal lymph nodes.

Additionally, the back portion of the nasal floor is likely to drain into the parotid lymph nodes.

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• Spine Anatomy: Complete Guide with Parts, Names, Functions & Diagram

Human Head

• Skull Anatomy: Complete Guide with Parts, Names, Functions & Diagram
• Ultimate Guide to Eye Anatomy: Parts, Structure, Functions & Diagram
• Tongue Anatomy: Complete Guide with Parts, Names, Functions & Diagram
• Mouth Anatomy: Complete Guide with Parts, Names, Functions & Diagram
• Complete Guide to Tooth Anatomy: Learn Parts, Names & Diagram
• Ultimate Guide to Ear Anatomy: Parts, Structure, Functions & Diagram

Organs

• Kidney Anatomy: Complete Guide with Parts, Names, Functions & Diagram
• Liver Anatomy: Complete Guide with Parts, Names, Functions & Diagram
• Heart Anatomy: Complete Guide with Parts, Names, Functions & Diagram

External Sources-

• Wikipedia
• KenHub
• Optometrists
• Cleveland Clinic
• American Academy of Ophthalmology