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Nov 16, 2025 PDF Available

Topic Overview

Nose – Introduction

The nose functions in respiration (air passage) and olfaction (sense of smell).
The olfactory mucosa lines the upper one-third of the nasal cavity — including the roof and adjacent medial and lateral walls.
The respiratory mucosa lines the lower two-thirds — highly vascular and ciliated to warm, moisten, and filter inspired air.

External Nose

Framework: partly bony and partly cartilaginous.
- Bony part: nasal bones and frontal process of maxilla.
- Cartilaginous part: septal cartilage, superior and inferior lateral cartilages, and small alar cartilages.
Surface features: root, dorsum, tip, anterior nares, and columella.
Skin innervation: by branches of external nasal, infratrochlear, and infraorbital nerves.
Function: filters and conditions air before it enters the respiratory tract.

Nasal Cavity

Extends from external nares (nostrils) to posterior nasal apertures (choanae).
Divided into two halves by the nasal septum, each with roof, floor, medial, and lateral walls.
Dimensions: length ~7 cm, height ~5 cm, width near floor ~1.5 cm.
Roof: formed by nasal bones (anterior), cribriform plate of ethmoid (middle), and sphenoid bone (posterior).
Floor: formed by the palatine process of the maxilla and horizontal plate of the palatine bone.
Mucosa:
- Upper third → olfactory region (with olfactory receptor cells).
- Lower two-thirds → respiratory region (rich in blood vessels and glands).

Clinical Anatomy

Rhinitis (Common Cold): inflammation of nasal mucosa due to viral or allergic causes.
Sinusitis: infection spreading from the nasal cavity to paranasal sinuses (especially maxillary).
CSF Rhinorrhea: fracture of the cribriform plate may tear olfactory nerve filaments, causing leakage of cerebrospinal fluid from the nose.
Epistaxis (Nosebleed): common in Little’s area (Kiesselbach’s plexus) on the anterior nasal septum where several arteries anastomose.
Deviated Nasal Septum: causes nasal obstruction, headaches, and predisposes to sinus infections.
Spread of Infection:
- To anterior cranial fossa through cribriform plate.
- To lacrimal sac and duct, leading to dacryocystitis.

Nasal Septum

The nasal septum is a median osseocartilaginous partition dividing the nasal cavity into right and left halves.
Parts:
- Bony part: formed mainly by the vomer and perpendicular plate of the ethmoid, with small contributions from the nasal spine of frontal bone, rostrum of sphenoid, and nasal crests of maxilla and palatine bones.
- Cartilaginous part: formed by the septal cartilage and septal processes of inferior nasal cartilages.
- Cuticular part: formed by fibrofatty tissue covered by skin, forming the columella.
The septum is rarely perfectly midline; mild deviation is common due to unequal growth of its components.

Arterial Supply

Anterosuperior: anterior and posterior ethmoidal arteries.
Anteroinferior: septal branch of the superior labial branch of facial artery.
Posterosuperior: sphenopalatine artery (main supply).
These vessels form an anastomotic network known as Kiesselbach’s plexus (Little’s area) — a common site for epistaxis.

Venous Drainage

Veins form a plexus prominent in Little’s area.
Drains anteriorly into facial vein and posteriorly via sphenopalatine vein to the pterygoid venous plexus.

Nerve Supply

General sensation:
- Anterosuperior → internal nasal branches of anterior ethmoidal nerve.
- Posteroinferior → nasopalatine branch of pterygopalatine ganglion.
Special sensation (smell): olfactory nerves in the upper part.

Lymphatic Drainage

Anterior half → submandibular nodes.
Posterior half → retropharyngeal and deep cervical nodes.

Clinical Anatomy (Nasal Septum)

Epistaxis: Sphenopalatine artery (artery of epistaxis) commonly bleeds from Little’s area.
Deviated septum: can cause recurrent sinusitis, rhinitis, and nasal obstruction, requiring surgical correction.

Lateral Wall of Nose

Highly irregular due to three conchae (turbinates) that increase surface area for air conditioning.
Separates the nasal cavity from:
- Orbit (above, via ethmoidal air sinuses),
- Maxillary sinus (below),
- Lacrimal sac and duct (anteriorly).

Parts of Lateral Wall

Vestibule: lined by skin with coarse hairs (vibrissae).
Atrium of middle meatus: small depression behind vestibule.
Posterior part: contains superior, middle, and inferior conchae with their corresponding meatuses.

Skeleton of Lateral Wall

Bony part: nasal bone, frontal process of maxilla, lacrimal bone, ethmoidal labyrinth (with conchae), inferior nasal concha, perpendicular plate of palatine bone, medial pterygoid plate.
Cartilaginous part: superior and inferior nasal cartilages and small alar cartilages.
Cuticular part: fibrofatty tissue covered by skin.

Conchae and Meatuses

Conchae

Curved, thin bony projections directed downward and medially.
Inferior concha: independent bone.
Middle and superior conchae: parts of the ethmoid bone.

Meatuses (Passages beneath the conchae)

Inferior meatus: below inferior concha; receives nasolacrimal duct guarded by Hasner’s valve.
Middle meatus: below middle concha; contains:
- Ethmoidal bulla: produced by middle ethmoidal sinuses.
- Hiatus semilunaris: curved groove below the bulla.
- Infundibulum: short passage leading to frontal sinus and anterior ethmoidal sinus openings.
Superior meatus: below superior concha; receives posterior ethmoidal sinuses.

Clinical Anatomy (Lateral Wall)

Nasal obstruction: due to hypertrophy of conchae or deviated septum.
Infection spread: nasal infections may involve paranasal sinuses via meatal openings.
Epistaxis: can also occur from posterior septal branches near sphenopalatine region.
Rhinitis and sinusitis: commonly affect middle meatus region due to sinus openings.

Olfactory Nerve (1st Cranial Nerve)

Structure and Pathway

Composed of 16–20 million bipolar olfactory cells situated in the olfactory mucosa of the upper nasal cavity.
Each cell has:
- A peripheral process ending in olfactory hairs that detect odor molecules.
- A central process forming fine olfactory filaments that pass through the cribriform plate of the ethmoid.
These filaments synapse in the olfactory bulb within specialized glomeruli.
Mitral and tufted cells in the bulb send axons through the olfactory tract to the anterior perforated substance, uncus, and primary olfactory cortex (periamygdaloid and prepiriform areas).
Unlike other sensory pathways, this system bypasses the thalamus and directly projects to the cortex.

Clinical Anatomy

Anosmia: complete loss of smell due to ageing, trauma, or infection.
Hyposmia: partial loss of smell, often transient in rhinitis.
Cacosmia: perception of foul odors in nasal infection.
CSF rhinorrhea: fracture of the cribriform plate may tear olfactory filaments, causing cerebrospinal fluid leakage from the nose.

Paranasal Sinuses

Overview

Air-filled cavities within the frontal, maxillary, sphenoidal, and ethmoidal bones.
They open into the lateral wall of the nasal cavity and serve to:
- Reduce skull weight,
- Warm and humidify inspired air,
- Act as resonating chambers for voice.
Absent or rudimentary at birth; enlarge rapidly by 6–7 years and again at puberty.

Frontal Sinus

Lies within the frontal bone, deep to the superciliary arches.
Opens into the middle meatus via the frontonasal duct or infundibulum.
Average size ≈ 2.5 cm in all dimensions; often asymmetrical.
Pain in inflammation is felt above the eyes and root of the nose.

Maxillary Sinus

Largest sinus, pyramidal in shape, within the body of maxilla.
Roof: floor of orbit; floor: related to upper molar roots.
Opens into middle meatus through the hiatus semilunaris.
Infection leads to maxillary sinusitis; pain referred to upper teeth and cheek.

Ethmoidal Sinuses

Multiple small air cells within the ethmoidal labyrinth.
- Anterior cells → open into middle meatus.
- Middle cells → form ethmoidal bulla.
- Posterior cells → open into superior meatus.
Closely related to the orbit, so infection may spread to the eye.

Sphenoidal Sinus

Occupies the body of sphenoid bone below the pituitary fossa.
Opens into the spheno-ethmoidal recess above the superior concha.
Inflammation may cause deep headache behind the eyes or at the vertex.

Clinical Anatomy of Paranasal Sinuses

Sinusitis: inflammation causing nasal discharge, facial pain, and headache.
Frontal sinusitis: pain above the orbit.
Maxillary sinusitis: pain over upper jaw and teeth.
Ethmoidal sinusitis: pain near inner canthus of the eye.
Sphenoidal sinusitis: pain deep in the head or behind eyes.
Chronic sinusitis may lead to postnasal drip and altered resonance of voice.

Pterygopalatine Fossa

Location and Shape

Small pyramidal space located deep below the apex of the orbit, between the pterygoid process and posterior surface of the maxilla.

Boundaries

Anterior: posterior surface of maxilla.
Posterior: root of pterygoid process and greater wing of sphenoid.
Medial: perpendicular plate of palatine bone.
Lateral: opens to infratemporal fossa via pterygomaxillary fissure.
Roof: body of sphenoid.
Floor: pyramidal process of palatine bone.

Communications

Anteriorly: with orbit through inferior orbital fissure.
Posteriorly: with middle cranial fossa (foramen rotundum), foramen lacerum (pterygoid canal), and pharynx (palatinovaginal canal).
Medially: with nasal cavity through sphenopalatine foramen.
Laterally: with infratemporal fossa via pterygomaxillary fissure.
Inferiorly: with oral cavity through greater and lesser palatine canals.

Contents

Third part of maxillary artery and branches.
Maxillary nerve (V₂) and branches: ganglionic, zygomatic, posterior superior alveolar.
Pterygopalatine ganglion with its parasympathetic, sympathetic, and sensory fibers.

Applied Importance

Serves as a neurovascular hub linking orbit, nose, mouth, and cranial fossa.
Pterygopalatine neuralgia causes deep pain behind the maxilla or in the palate due to irritation of the ganglion.

Maxillary Nerve (V₂)

The maxillary nerve is the second division of the trigeminal nerve (CN V).
It is purely sensory.
Origin: From the trigeminal ganglion in the middle cranial fossa.
Course:
- Leaves the cranial cavity via the foramen rotundum to enter the pterygopalatine fossa.
- Gives off several branches before continuing as the infraorbital nerve, which passes through the inferior orbital fissure, infraorbital canal, and emerges on the face via the infraorbital foramen.

Branches

Zygomatic nerve → divides into:
- Zygomaticotemporal nerve (to temple and lacrimal nerve for secretomotor fibres).
- Zygomaticofacial nerve (to cheek skin).
Infraorbital nerve → continuation of maxillary nerve; supplies:
- Middle superior alveolar nerve: upper premolars.
- Anterior superior alveolar nerve: upper incisors, canines, maxillary sinus, and anterior nasal wall.
- Terminal branches: palpebral, nasal, and labial (skin and mucosa of face).
Pterygopalatine branches → connect the nerve to the pterygopalatine ganglion.

Pterygopalatine Ganglion (Sphenopalatine / Meckel’s / Ganglion of Hay Fever)

Features

Largest parasympathetic peripheral ganglion.
Acts as a relay center for secretomotor fibres to:
- Lacrimal gland
- Nasal, palatine, and pharyngeal mucous glands
Location: In the pterygopalatine fossa, below the maxillary nerve, in front of the pterygoid canal, lateral to the sphenopalatine foramen.
Relation: Topographically with maxillary nerve, functionally connected with facial nerve (via greater petrosal branch).

Roots

Parasympathetic (motor) root:
- From the nerve of the pterygoid canal (formed by the greater petrosal and deep petrosal nerves).
- Fibres relay in the ganglion and pass to the lacrimal, nasal, palatine, and pharyngeal glands.
Sympathetic root:
- From the deep petrosal nerve, fibres pass without relay to supply vasomotor innervation to nasal and palatal mucosa.
Sensory root:
- From the maxillary nerve, fibres pass through the ganglion without relay.

Branches

Orbital branches: to periosteum of orbit and orbitalis muscle.
Palatine branches:
- Greater palatine nerve → hard palate, upper gums.
- Lesser palatine nerves → soft palate, tonsil.
Nasal branches:
- Lateral posterior superior nasal branches → conchae.
- Medial posterior superior nasal branches → nasal roof and septum.
- Nasopalatine nerve → anterior hard palate via incisive foramen.
Pharyngeal branch: via palatinovaginal canal → nasopharynx.
Lacrimal branch: secretomotor fibres through zygomaticotemporal and lacrimal nerves to lacrimal gland.

Clinical Anatomy

Trigeminal neuralgia (V₂): causes severe pain in the midface; the nerve can be anaesthetized at the foramen rotundum.
Pterygopalatine ganglion irritation/infection: leads to congestion and overactivity of glands → runny nose and lacrimation (hence called Ganglion of Hay Fever).
Sneeze reflex: the maxillary nerve carries the afferent limb (general sensation from nasal mucosa).

Summary of Pterygopalatine Fossa

The fossa contains structures often remembered in groups of three:

Three Contents:

Maxillary nerve
Third part of maxillary artery
Pterygopalatine ganglion

Three Names of Ganglion:

Sphenopalatine
Pterygopalatine
Ganglion of Hay Fever / Meckel’s

Three Structures in Posterior Wall:

Maxillary nerve → foramen rotundum
Nerve of pterygoid canal → pterygoid canal
Pharyngeal branch → palatinovaginal canal

Three Through Inferior Orbital Fissure:

Infraorbital nerve
Zygomatic nerve
Orbital branches of the ganglion

Three Inferior Openings:

Greater palatine nerve + vessels
Two lesser palatine nerves + vessels

Three Medial Openings:

Nasopalatine nerve + sphenopalatine vessels
Medial and lateral posterior superior nasal branches

Three Roots of Ganglion:

Sensory, sympathetic, and secretomotor

3 × 2 Branches of Ganglion:

Orbital, pharyngeal, lacrimal, anterior palatine, posterior palatine, nasopalatine

3 × 2 Branches of Third Part of Maxillary Artery:

Posterior superior alveolar, infraorbital, sphenopalatine, pharyngeal, artery of pterygoid canal, greater palatine

Facts to Remember

Artery of epistaxis: The sphenopalatine artery is the main vessel responsible for nasal bleeding.
The upper few millimeters of the nasal septum and lateral wall are lined by olfactory epithelium, which contains bipolar receptor neurons for smell.
Most nerves and vessels supplying the lateral wall and septum are common, differing mainly in size and distribution.
Maxillary sinusitis is the most frequent form of chronic sinus infection.
The middle meatus receives the openings of four paranasal sinuses — frontal, maxillary, and anterior and middle ethmoidal.
Sinusitis can result from air pollution, allergy, or infection spreading from the nasal cavity.
The pterygopalatine ganglion is known as the ganglion of hay fever, as its irritation causes rhinorrhea (nasal discharge) and lacrimation due to overactivity of nasal and lacrimal glands.
Referred pain:
- Maxillary sinusitis → upper teeth and cheek region.
- Ethmoidal sinusitis → medial side of orbit.
- Frontal sinusitis → forehead.

Clinicoanatomical Problem

Case:
A child playing outdoors during hot summer picks his nose and experiences sudden bleeding.

Question 1: What is the source of the bleeding?

The source is injury to the rich capillary plexus at the anteroinferior part of the nasal septum, known as Kiesselbach’s plexus or Little’s area.
This site is the most common location for epistaxis (nosebleed).

Question 2: Which arteries supply the nasal septum?

Anterior ethmoidal artery – branch of the ophthalmic artery (from internal carotid).
Superior labial artery – branch of the facial artery (from external carotid).
Sphenopalatine artery – terminal branch of the maxillary artery (from external carotid).
Greater palatine artery – branch of the maxillary artery.

Explanation:

These arteries anastomose in Little’s area to form a vascular network highly prone to rupture in trauma, infection, or dry climates.
In recurrent epistaxis, cauterization or arterial ligation may be required.

Frequently Asked Questions

1. What are the boundaries of the nasal cavity?

Roof: Nasal bone, cribriform plate of ethmoid, sphenoid body.
Floor: Palatine process of maxilla and horizontal plate of palatine bone.
Medial wall: Nasal septum.
Lateral wall: Formed by conchae and meatuses.

2. What is Little’s area and why is it important?

A vascular area in the anteroinferior part of the nasal septum.
Site of anastomosis of sphenopalatine, greater palatine, anterior ethmoidal, and superior labial arteries.
Commonest site of epistaxis (nosebleed).

3. What are the openings in the middle meatus?

Frontal sinus (via frontonasal duct).
Maxillary sinus (via hiatus semilunaris).
Anterior and middle ethmoidal air cells.

4. Which sinus is most commonly infected?

Maxillary sinus, due to poor drainage and close relation with upper molar teeth.

5. What is the nerve of the pterygoid canal?

Formed by the greater petrosal (parasympathetic) and deep petrosal (sympathetic) nerves.
Connects the facial nerve with the pterygopalatine ganglion.

6. Why is the pterygopalatine ganglion called the “ganglion of hay fever”?

Because its overstimulation causes nasal secretion and lacrimation during allergic rhinitis (hay fever).

7. What are the communications of the pterygopalatine fossa?

Anteriorly: Orbit via inferior orbital fissure.
Posteriorly: Middle cranial fossa (foramen rotundum), foramen lacerum (pterygoid canal), pharynx (palatinovaginal canal).
Medially: Nasal cavity (sphenopalatine foramen).
Laterally: Infratemporal fossa (pterygomaxillary fissure).
Inferiorly: Oral cavity (greater and lesser palatine canals).

8. What are the branches of the maxillary nerve in the pterygopalatine fossa?

Ganglionic branches (to pterygopalatine ganglion).
Zygomatic nerve.
Posterior superior alveolar nerve.
Infraorbital nerve (continuation).

9. What is the sensory supply of the nasal cavity?

Anterosuperior part: Anterior ethmoidal nerve (ophthalmic division).
Posteroinferior part: Nasopalatine and greater palatine nerves (maxillary division).

10. Which sinuses open into the superior meatus?

Posterior ethmoidal air cells.

11. What is the function of the paranasal sinuses?

Lighten skull bones, improve resonance of voice, humidify air, and act as air reservoirs.

12. What are the effects of pterygopalatine ganglion inflammation?

Causes pain in the root of the nose, eye, and palate, and increased nasal secretion and lacrimation.

13. Why can sinusitis cause dental pain?

Due to proximity of maxillary sinus to roots of upper teeth and their shared innervation by the infraorbital and superior alveolar nerves.

14. What is the sensory nerve of the nasal septum?

Anterosuperior part: Anterior ethmoidal nerve.
Posteroinferior part: Nasopalatine nerve.

15. How does infection from nasal cavity spread to the eye?

Through the ethmoidal sinuses, which lie between the nasal cavity and the orbit.

Multiple Choice Questions

1. Which of the following is known as the artery of epistaxis?
A. Anterior ethmoidal artery
B. Greater palatine artery
C. Sphenopalatine artery
D. Superior labial artery
→ Answer: C. Sphenopalatine artery