Anatomy of the Nose: External Nose and Nasal Cavity
The nose is the uppermost part of the respiratory tract and the peripheral organ of smell. It consists of the external nose, the paired nasal cavities and closely related paranasal sinuses. Its framework of bone and cartilage maintains an open airway, while its vascular mucosa warms, humidifies and filters inspired air.
Understanding nasal anatomy is essential for examining obstruction, discharge, epistaxis, trauma, foreign bodies and sinus disease. Important neighbouring structures include the orbit, anterior cranial fossa, oral cavity, nasopharynx, paranasal sinuses and lacrimal apparatus.
The nasal cavity extends from the anterior nares to the posterior choanae. Its roof lies close to the anterior cranial fossa, its floor is the hard palate, its medial wall is the septum and its lateral wall carries the conchae and meatuses.
Learning objectives
- Identify the surface landmarks and supporting framework of the external nose.
- Describe the boundaries and major regions of the nasal cavity.
- Explain the structure of the nasal septum, conchae and meatuses.
- State the drainage sites of the paranasal sinuses and nasolacrimal duct.
- Outline the arterial, venous, lymphatic and nerve supply.
- Relate the anatomy to smell, airflow, epistaxis, sinusitis and trauma.
General divisions
A pyramidal projection on the face formed by bone, cartilage, muscles, skin and soft tissue.
Two chambers separated by the septum, extending from the nostrils to the nasopharynx.
Paired frontal, maxillary, ethmoidal and sphenoidal air spaces that communicate with the nasal cavity.
For the full ENT context, review the Rhinology overview of nose anatomy, physiology and common conditions.
External nose
Surface landmarks
- Root: upper attachment between the eyes.
- Bridge and dorsum: ridge descending from the root toward the tip.
- Apex: projecting tip of the nose.
- Alae: rounded lateral wings forming the outer margins of the nostrils.
- Nares: anterior openings into the nasal vestibules.
- Columella: tissue separating the nostrils inferiorly.
Skeletal framework
| Part | Main structures | Importance |
|---|---|---|
| Bony upper third | Nasal bones, frontal processes of the maxillae and nasal part of the frontal bone. | Provides a firm bridge; fractures commonly affect the nasal bones. |
| Cartilaginous lower part | Septal cartilage, paired lateral nasal cartilages, major alar cartilages and smaller accessory cartilages. | Maintains shape while allowing flexibility at the tip and nostrils. |
| Soft tissue | Skin, subcutaneous tissue and muscles of facial expression. | Controls nostril width and contributes to facial expression. |
The muscles include nasalis, procerus and depressor septi nasi, supplied by branches of the facial nerve. They can compress or dilate the nostrils, although quiet nasal airflow depends mainly on the passive airway and mucosal resistance.
Nasal vestibule and nasal cavity
The vestibule is the most anterior expanded part just inside each nostril. It is lined by skin containing sebaceous glands and coarse hairs called vibrissae, which trap large particles. At the limen nasi, the lining changes from skin to respiratory mucosa.
The nasal cavity proper extends posteriorly to the choanae. The septum divides it into right and left passages, which may be unequal because minor septal deviation is common.
Boundaries of each nasal cavity
| Boundary | Main components | Key relation |
|---|---|---|
| Roof | Nasal and frontal bones anteriorly, cribriform plate of ethmoid centrally, body of sphenoid posteriorly. | The cribriform plate separates the olfactory mucosa from the anterior cranial fossa. |
| Floor | Palatine processes of the maxillae and horizontal plates of the palatine bones. | Forms the hard palate and separates the nasal cavity from the oral cavity. |
| Medial wall | Nasal septum. | Separates the two nasal cavities. |
| Lateral wall | Maxilla, lacrimal, ethmoid, inferior nasal concha, palatine and sphenoid bones. | Bears the conchae and the sinus-drainage pathways. |
| Anterior opening | Naris and vestibule. | Communicates with the exterior. |
| Posterior opening | Choana. | Communicates with the nasopharynx. |
Nasal septum
The septum is partly bony and partly cartilaginous. Its main components are:
- Perpendicular plate of the ethmoid: forms the superior bony part.
- Vomer: forms much of the posteroinferior bony part.
- Septal cartilage: forms the anterior mobile portion.
- Maxillary and palatine crests: support the septum inferiorly.
Septal deviation may narrow one side and alter airflow. After nasal trauma, blood can collect between the cartilage and its perichondrium, producing a septal haematoma. This is an ENT emergency because pressure can cause cartilage necrosis, abscess formation and later saddle-nose deformity.
A patient with nasal trauma and bilateral soft septal swelling needs urgent drainage assessment. Do not dismiss the obstruction as simple swelling or a deviated septum.
Lateral wall: conchae and meatuses
The superior, middle and inferior nasal conchae curve medially from the lateral wall. The superior and middle conchae are parts of the ethmoid bone; the inferior concha is a separate bone. They increase mucosal surface area and create turbulent airflow, improving warming, humidification, filtration and contact with olfactory mucosa.
A meatus is the passage below its corresponding concha. The sphenoethmoidal recess lies above the superior concha.
| Passage | Structures that drain or open here | Clinical note |
|---|---|---|
| Sphenoethmoidal recess | Sphenoidal sinus. | Located high and posterior, above the superior concha. |
| Superior meatus | Posterior ethmoidal air cells. | Small passage below the superior concha. |
| Middle meatus | Frontal sinus, maxillary sinus, and anterior and middle ethmoidal air cells. | The ostiomeatal complex is a major pathway in chronic rhinosinusitis. |
| Inferior meatus | Nasolacrimal duct. | Explains why tears enter the nose and may increase nasal discharge during crying. |
| Common meatus | Longitudinal passage between the conchae and septum. | Allows airflow through the central nasal cavity. |
Mucosa and functional regions
Contains vibrissae, sebaceous glands and stratified squamous epithelium.
Lined mainly by ciliated pseudostratified columnar epithelium with goblet cells and vascular lamina propria.
Contains olfactory receptor neurons, supporting cells and glands near the superior concha and upper septum.
Mucus traps particles while cilia move the mucus posteriorly toward the nasopharynx for swallowing. The rich submucosal vascular network transfers heat to inspired air. Serous and mucous secretions humidify the air and support local defence.
Paranasal sinuses
The frontal, maxillary, ethmoidal and sphenoidal sinuses are mucosa-lined spaces in bones surrounding the nasal cavity. They lighten the skull, contribute to voice resonance and produce mucus that drains into the nose.
- Frontal sinuses: lie above the orbits and drain toward the middle meatus.
- Maxillary sinuses: lie in the maxillae, lateral to the nasal cavity and below the orbits. Their ostia are high on the medial wall, so drainage may be impaired.
- Ethmoidal air cells: lie between the nasal cavity and orbit; anterior and middle groups drain to the middle meatus, posterior cells to the superior meatus.
- Sphenoidal sinuses: lie in the body of the sphenoid near the pituitary gland, optic nerves and internal carotid arteries and drain to the sphenoethmoidal recess.
These close relations explain orbital, dental and intracranial complications of sinus infection. The thin lamina papyracea separates ethmoidal cells from the orbit.
Blood supply
The nose has a rich arterial supply from both internal and external carotid systems, with extensive anastomoses.
Major arteries
- Sphenopalatine artery: terminal branch of the maxillary artery and a major supply to the posterior cavity.
- Anterior and posterior ethmoidal arteries: branches of the ophthalmic artery from the internal carotid system.
- Greater palatine artery: reaches the septum through the incisive canal.
- Superior labial and lateral nasal branches: arise from the facial artery and supply the anterior region and external nose.
Kiesselbach area
Kiesselbach plexus, also called Little area, lies on the anteroinferior septum. Several arterial branches anastomose close to the surface, making it the commonest site of anterior epistaxis, particularly in children and young adults. Posterior epistaxis more often arises from branches of the sphenopalatine artery and can be severe.
Venous drainage broadly follows the arteries to facial, ophthalmic and pterygoid venous channels. Connections to the cavernous sinus and intracranial veins help explain how infection can spread from the central face or nasal region.
Nerve supply
| Function | Nerve supply | Distribution |
|---|---|---|
| Smell | Olfactory nerve (CN I). | Receptor axons pass through the cribriform plate to the olfactory bulb. |
| General sensation: anterior-superior | Ophthalmic division of trigeminal nerve (V1), mainly anterior ethmoidal branches. | Anterior and upper septum and lateral wall. |
| General sensation: posterior-inferior | Maxillary division (V2), including nasopalatine and posterior lateral nasal branches. | Posterior and lower septum and lateral wall. |
| Glandular secretion | Parasympathetic fibres from the facial nerve via the greater petrosal nerve and pterygopalatine ganglion. | Stimulates nasal glands. |
| Vascular tone | Sympathetic fibres from the superior cervical ganglion via the deep petrosal nerve. | Produces vasoconstriction and regulates mucosal blood flow. |
Fracture of the cribriform plate can tear olfactory fibres, causing anosmia, and may create a route for cerebrospinal fluid rhinorrhoea and ascending infection.
Lymphatic drainage
- The external nose drains mainly to submandibular nodes, with some drainage toward parotid nodes.
- The anterior nasal cavity drains mainly to submandibular nodes.
- The posterior nasal cavity drains toward retropharyngeal and upper deep cervical nodes.
Lymphatic pathways influence the spread of infection and malignant disease and should be considered during the ENT examination of the neck.
Functions of the nose
- Air conduction: provides the normal upper-airway route.
- Filtration: vibrissae, mucus and cilia trap and remove particles.
- Warming: the vascular mucosa transfers heat to inspired air.
- Humidification: mucosal secretions add moisture.
- Olfaction: odorants stimulate receptors in the olfactory region.
- Defence: mucociliary clearance, sneezing and immune factors limit entry of pathogens.
- Voice resonance: the nasal cavity and sinuses modify vocal quality.
Clinical anatomy
Anterior bleeding commonly arises from Little area; severe posterior bleeding often involves sphenopalatine branches.
Deviation, mucosal oedema, turbinate enlargement, polyps or masses may narrow airflow.
Oedema around the middle meatus can block the frontal, maxillary and anterior ethmoidal drainage pathway.
Nasal or skull-base trauma may cause deformity, septal haematoma, anosmia or clear CSF rhinorrhoea.
Children may insert objects along the floor of the nasal cavity. Unilateral foul-smelling discharge is an important clue. Review safe nasal foreign-body assessment and removal. Before any procedure, use appropriate ENT instruments with good lighting and direct visualisation.
Examination orientation
Anterior rhinoscopy assesses the vestibule, septum, inferior turbinate, part of the middle turbinate and the character of discharge. Endoscopy extends the view to the middle meatus, sphenoethmoidal recess, posterior septum, choanae and nasopharynx. Imaging is selected according to the clinical question; review ENT investigations and interpretation.
Clinical scenario
A 13-year-old presents with recurrent bright-red bleeding from the right nostril after nose picking. He is stable, and anterior rhinoscopy shows a small bleeding point on the anteroinferior septum.
Interpretation: the likely source is Kiesselbach plexus in Little area. Sit the patient forward, apply firm pressure to the soft part of the nose and manage according to the epistaxis protocol. The location reflects the superficial anastomotic arterial network on the anterior septum.
Key examination points
- The nose consists of the external nose, paired nasal cavities and paranasal sinuses.
- The septum is formed mainly by septal cartilage, the perpendicular plate of ethmoid and vomer.
- The roof includes the cribriform plate; the floor is the hard palate.
- Conchae enlarge the surface area and create airflow turbulence.
- The middle meatus receives drainage from the frontal, maxillary and anterior/middle ethmoidal sinuses.
- The nasolacrimal duct opens into the inferior meatus.
- CN I supplies smell; V1 and V2 supply general sensation.
- Little area on the anterior septum is the commonest site of anterior epistaxis.
- A septal haematoma after trauma is an ENT emergency.
References and further reading
- NCBI Bookshelf: Anatomy, Head and Neck, Nasal Cavity.
- NCBI Bookshelf: Anatomy, Head and Neck, Nose.
- NCBI Bookshelf: Anatomy, Head and Neck, Nose Paranasal Sinuses.
- TeachMeAnatomy: The Nasal Cavity.
- OpenStax Anatomy and Physiology: Organs and Structures of the Respiratory System.
For education only. Apply findings together with current Uganda Clinical Guidelines, local protocols and senior ENT advice.
