Anatomy of the Nose😊

Anatomy of the Nose

• External nose.

• Internal nose.

Openings into Nasal Meatuses

Meatus / Recess	Structures opening	Opens at
Sphenoethmoidal recess	ㅤ	ㅤ
ㅤ	• Sphenoid sinus	Behind Superior turbinate
Superior meatus	ㅤ	ㅤ
ㅤ	• Posterior ethmoidal sinus	ㅤ
Middle meatus	ㅤ	ㅤ
ㅤ	• Middle ethmoidal sinus	Into bulla ethmoidalis
ㅤ	• Maxillary sinus	Into infundibulum
ㅤ	• Frontal sinus • Anterior ethmoidal sinus • + Infundibulum	Into Hiatus Semilunaris ↳ Osteomeatal complex / ↳ Picadle’s circle
ㅤ	• Sphenopalatine foramen	8 mm behind middle turbinate
ㅤ	• + DCR done here (Endonasal dacryocystorhinostomy)	• In Dacrocystitis (Lacrimal Sac)
Inferior meatus	ㅤ	ㅤ
ㅤ	• Nasolacrimal duct	• Guarded by valve of Hasner • Opens Downwards, Backwards and Laterally
ㅤ	• Eustachian tube	8mm behind posterior part of inferior turbinate

• Hiatus semilunaris
• between Uncinate process and Bulla ethmoidalis.
• Frontal and Anterior ethmoidal sinuses → drain into hiatus semilunaris.
• → Leads to the infundibulum.
• Maxillary sinus drains into the Infundibulum.

• Common drainage point:
• Osteomeatal complex / Picadli's Circle
• Blockage here causes retention of secretions, provoking sinusitis.

External Nose

• Upper 1/3rd is a bony part.

• Lower 2/3rds is a cartilaginous part.

Bony part:

• Paired bones:
• 2 nasal bones.
• 2 ascending processes of maxilla.

• Unpaired bones:
• Frontal bone (from above).

• 2 paired bones+ 1 unpaired bone → Bony part

Cartilaginous part:

• Paired cartilages:
• Upper lateral cartilage.
• Lower lateral cartilage.
• Sesamoid cartilage

• Unpaired cartilage:
• Septum.

• 3 paired cartilages + 1 unpaired cartilage → Cartilaginous part

Important anatomical points:

• Nasion:
• Point where Frontal bone meets nasal bone in midline.

• Rhinion:
• Point where nasal bone meets upper lateral cartilage in midline.

• Limen Nasi:
• Lower border of the upper lateral cartilage.

Internal Nasal Valve

• At the level of vestibule
• Narrowest portion of nasal cavity
• Its Boundaries are:-
• Medially - Septum
• Superiorly - Limen Nasii
• Laterally - Head of inferior turbinate
• Angle: 10–15°

• If DNS present → further narrowing at vestibule → nasal obstruction

Internal Nose (Nasal Cavity Proper)

• Inlet is the vestibule

• Outlet is the choana
• Choana:
• Communication between nasal cavity and nasopharynx.

• Walls:
• Roof of the nose.
• Floor of the nose.
• Medial wall is the septum,
• dividing right and left nasal cavity.

• Lateral wall:
• Has 3 bony projections called Turbinates/Conchae.

• Epithelium:
• Vestibule:
• Lined by stratified squamous epithelium.
• Has hair follicles.

• Rest of the nose:
• Lined by Respiratory epithelium
• Pseudostratified ciliated columnar epithelium
• Also known as Schneiderian membrane.

• Olfactory cleft:
• Present in the roof of the nose.
• Has olfactory epithelium.
• Boundaries:
• Medially: Upper part of Septum.
• Laterally: Superior Turbinate.
• Roof: Cribriform of ethmoidal plate.

Roof and Floor of the Nose

• Roof of the nose:
• Formed by 3 bones.
• Separates nasal cavity from Anterior Cranial Fossa.
• Parts:



• Anterior 1/3rd: Frontal bone.
• Middle 1/3rd: Cribriform plate of ethmoid bone.
• Posterior 1/3rd: Body of Sphenoid bone.

• Floor of the nose:
• Formed by 2 bones.
• Parts:
• Anteriorly: Crest of Maxilla bone.
• Posteriorly: Crest of Palatine bone.

Medial Wall of Nose

• Formed by the Septum.
• Septum is made of:
• Cartilaginous part.
• Bony part.

• Anteriorly: Cartilaginous part.
• Septal Cartilage / Quadrangular Cartilage.

• Posteriorly: Bony part.
• Above → Perpendicular plate of Ethmoid bone
• Below → Vomer bone

• Small contributions from:
• Nasal spine of frontal bone.
• Rostrum of the sphenoid bone.
• Crest of the maxilla bone
• Crest of the palatine bone

Blood Supply of Nose

Upper half:

• Supplied by Internal Carotid Artery (ICA).

• ICA branch: Ophthalmic Artery.
• Ophthalmic artery branches:
• Anterior Ethmoidal Artery (AEA):
• Supplies anterosuperior septum.
• Posterior Ethmoidal Artery (PEA):
• Supplies posterosuperior septum.

Lower half:

• Supplied by External Carotid Artery (ECA).

• ECA branches: Facial Artery and Internal Maxillary Artery.
• Facial Artery branch:
• Superior Labial Artery:
• Supplies anteroinferior septum.
• Internal Maxillary Artery branches:
• Supplies posteroinferior septum.
• Sphenopalatine artery
• Greater Palatine Artery

Plexuses:

• Kiesselbach's Plexus/Little's area:
• Arterial Plexus.
• Anastomosis of arteries in anteroinferior septum
• except posterior ethmoidal artery
• Bleeding here is Anterior Epistaxis.
• Mild bleeding
• Common in children
• M/c: Trauma

• Woodruff's Plexus:
• Venous plexus.
• Located in posteroinferior septum.
• Bleeding here is Posterior Epistaxis.
• Severe bleeding
• Common in adults
• M/c: HTN

Comparison of Anterior and Posterior Epistaxis:

Feature	Anterior Epistaxis	Posterior Epistaxis
Incidence	More common	Less common
Most Common Cause	Trauma	Hypertension
Age	Common in children	Common after 40 years of age
Bleeding	Mild	Severe
Rx	• Local pressure • Anterior pack	• Requires hospitalization • Postnasal pack

Artery Ligation Sites:

• Anterior and posterior ethmoidal arteries:
• Ligated near medial wall of orbit.

• Internal maxillary artery:
• Ligated in Pterygopalatine fossa.

• Sphenopalatine artery:
• Ligated in Sphenopalatine foramen.

Lateral Wall of Nose

• Has 3 bony projections called Turbinates/Concha.

• Turbinates:
1. Inferior Turbinate.
2. Middle Turbinate.
3. Superior Turbinate.
4. Supreme Turbinate.
• (Sometimes 4th)

• Superior and Middle turbinate are derived from Ethmoid Bone.

Meatuses:

• Spaces below the turbinates.

Openings into Nasal Meatuses

Meatus / Recess	Structures opening	Opens at
Sphenoethmoidal recess	ㅤ	ㅤ
ㅤ	• Sphenoid sinus	Behind Superior turbinate
Superior meatus	ㅤ	ㅤ
ㅤ	• Posterior ethmoidal sinus	ㅤ
Middle meatus	ㅤ	ㅤ
ㅤ	• Middle ethmoidal sinus	Into bulla ethmoidalis
ㅤ	• Maxillary sinus	Into infundibulum
ㅤ	• Frontal sinus • Anterior ethmoidal sinus • + Infundibulum	Into Hiatus Semilunaris ↳ Osteomeatal complex / ↳ Picadle’s circle
ㅤ	• Sphenopalatine foramen	8 mm behind middle turbinate
ㅤ	• + DCR done here (Endonasal dacryocystorhinostomy)	• In Dacrocystitis (Lacrimal Sac)
Inferior meatus	ㅤ	ㅤ
ㅤ	• Nasolacrimal duct	• Guarded by valve of Hasner • Opens Downwards, Backwards and Laterally
ㅤ	• Eustachian tube	8mm behind posterior part of inferior turbinate

• Hiatus semilunaris
• between Uncinate process and Bulla ethmoidalis.
• Frontal and Anterior ethmoidal sinuses → drain into hiatus semilunaris.
• → Leads to the infundibulum.
• Maxillary sinus drains into the Infundibulum.

• Common drainage point:
• Osteomeatal complex / Picadli's Circle
• Blockage here causes retention of secretions, provoking sinusitis.

Anterior Rhinoscopic Examination

Speculum used:

• Thudicum's nasal speculum (Non-self-retaining; common).

• Killian's Nasal speculum (Self-Retaining).

• Structures seen:
• Inferior Turbinate.
• Middle turbinate (portion).
• Septum.
• Floor of the nose.

• Diagnostic Nasal Endoscopy:
• Uses a 0-degree nasal endoscope / Hopkins's Rod.
• Visualizes:
• Medially: Septum.
• Laterally: Inferior turbinate.
• Above: Middle Turbinate.

Diagnostic Nasal Endoscopy

First pass

• Nasopharynx

• Inferior meatus

Second pass

• Superior meatus

• Opening of sphenoid sinus

• Sphenoethmoidal recess

• Openings of posterior ethmoid cells

Third pass:

• Middle meatus
• Bulla ethmoidalis
• Hiatus semilunaris

• Openings of:
• Frontal sinus
• Maxillary sinus
• Anterior ethmoid sinuses

Paranasal Sinuses

• Ventilation of sinus → during expiration

Development of 4 Paranasal Sinuses

1. Maxillary sinus.
• 1st Seen at birth
• Largest
• Fully developed by 12 yrs.

2. Frontal sinus.
• Rudimentary at birth → develops by 7–8 yrs → completes by 18 yrs.

3. Ethmoid sinus.
• Fully developed by 12 yrs.

4. Sphenoid sinus.

• All except Frontal sinus is seen at birth

1. Maxillary Sinus/ Antrum of Highmore

• Largest sinus.

• First sinus to develop.

• First sinus visible radiologically.



Part	Relation
Base	Separates sinus from lateral wall of nose
Apex	At level of zygoma
Roof	Related to floor of orbit
Floor	Related to 2nd premolar and 1st molar teeth

• Dental infections can cause Maxillary sinusitis.

• Tooth extraction can lead to an Oroantral fistula.

• Tooth caries can cause sinusitis.

Posterior wall:

• Related to Pterygopalatine fossa.

• Internal Maxillary Artery runs inside fossa.
• Gives off Sphenopalatine and Greater Palatine arteries.

Sphenopalatine foramen

• Posterior wall of maxillary sinus.

• Located behind middle turbinate (8 mm behind).

• Sphenopalatine artery enters here.

Anterior wall:

• Related to skin and subcutaneous tissue.

2. Frontal Sinus

• Air-filled pneumatization in frontal bone.

• Opens into Middle meatus → Frontal recess

• Located between Anterior and Posterior tables of frontal bone.
• Anterior boundary: Anterior table.
• Posterior boundary: Posterior table.

• MC mucocele, osteomyelitis

• Frontal sinusitis can spread to cause Frontal lobe abscess.

• Floor: Related to Roof of orbit.

• Right and Left sinuses do not communicate.

• Last sinus to develop;

• Absent at birth.

• Last to be seen on X-ray : At 6 yrs.

3. Ethmoid Sinus

• Air-filled cells between frontal and sphenoid sinuses.

Relation	Structure
Medially	Middle turbinate
Laterally	Medial wall of orbit
Superiorly	Fovea ethmoidalis

• Divided into anterior and posterior cells by Basal Lamella

• Most pneumatized at birth.

• M/c sinusitis leading to Orbital complications
• (D/t common venous drainage & lamina papyracea).

Specific ethmoid cells:

Cell	Feature / Relation
Agger nasi	Anterior most cell
Haller cell	Inferomedial to orbit/ Roof of maxillary sinus Block osteomeatal unit/picadelli circle → Sinusitis
Bulla ethmoidalis	Big cell behind agger nasi
Onodi cells	Posterior most cell extending into sphenoid sinus; related to Optic nerve and ICA
Kuhn cells	Anterior cells extending into frontal sinus (Frontoethmoidal cells); can block frontal sinus drainage

4. Sphenoid Sinus

• Posterior most sinus.

• L/c sinusitis.

• Roof:
• Has Sella turcica, which lodges the pituitary gland.
• Optic nerve passes closely.

• Lateral wall:
• Contains Cavernous sinus.
• Cavernous sinus contents: CNIII, CNIV, CNV, CNVI, ICA.

• Foramina related:
• Foramen Rotundum (above).
• Vidian Canal (below), for Vidian Nerve.

Types (based on pneumatization):

• Conchal type:
• Bony, small cavity.

• Presellar type:
• Less pneumatized.

• Sellar type:
• More pneumatized,
• easier for pituitary surgery
• Transnasal approach

Concha bullosa

• Pneumatization of middle turbinate
• Concha-turbinate.
• Bulla-air containing.

Venous Drainage of Nose

 

• Venous drainage of Face:
• Via deep facial vein → pterygoid venous plexus
• Via angular vein → superior ophthalmic vein
• Superior ophthalmic vein is valveless

Cavernous Sinus

• Paired sinus

• Located on either side of the body of the sphenoid bone

Location

• Middle cranial fossa

• Sides of Sella turcica

• Extends:
• From superior orbital fissure to foramen lacerum
• From lesser wing of sphenoid to petrous temporal bone

Contents

• Content: ICA, CN 6

• Medial:
• Pituitary gland
• Sphenoidal air sinus / body of sphenoid

• Lateral wall:
• CN III
• CN IV
• V1
• V2

• Superior:
• Optic nerve & optic chiasma.

Danger Triangle of Face:

• Area between Nasion and angles of lips.

• Infection can spread to cavernous sinus via valveless veins.

• Facial Vein
• Valveless
• allow bidirectional blood flow
• allow retrograde spread of infection from face to cavernous sinus

• Facial vein → Deep facial vein → Pterygoid venous plexus → Emissary vein → Cavernous sinus
• Most common route

• Facial vein → Angular vein → Superior ophthalmic vein → Cavernous sinus

• Meningioma (arachnoid origin) commonly along superior sagittal sinus

ICA rupture in cavernous sinus

• Carotidocavernous fistula

• Causes pulsatile proptosis

• due to its connection with superior orbital fissure

• CN VI injury → In cavernous sinus thrombosis

Functions of Nose

• Nasal Respiration.

• Protection of Lower Respiratory Tract.

• Vocal Resonance.

• Olfaction.

• Outlet for lacrimal secretions.

• Maximum airflow is in middle meatus during inspiration.

• Sinuses ventilate during expiration.

Smell Disorders

• Hyposmia: Decreased perception of smell.

• Anosmia: No perception of smell.

• Presbyosmia: Age-related decrease in smell.

• Parosmia/Cacosmia/Dysosmia:
• Cacosmia: Everything smells bad.
• Dysosmia: Altered perception of smell.

• Phantosmia: Perceiving a smell with no source.

One Liners

• External nose has 2 paired bones, 1 unpaired bone.

• External nose has 3 paired cartilages, 1 unpaired cartilage.

• Another name for pseudostratified columnar epithelium is Schneiderian membrane.

• Nasion is Frontal bone with nasal bone in midline.

• Rhinion is Nasal bone with upper lateral cartilage in midline.

• Limen Nasi is the Lower border of upper lateral cartilage.

• Turbinate not part of ethmoid bone is the Inferior Turbinate.

• Sinuses draining into hiatus semilunaris are Frontal and Anterior ethmoidal.

• Sinus draining into infundibulum is the Maxillary sinus.

• Sinus draining in superior meatus is the Posterior ethmoid sinus.

• Sphenoid sinus drains into sphenoethmoidal recess.

• Sinus absent at birth is the Frontal sinus.

• Sinus development coinciding with secondary dentition is the Maxillary sinus.

• Earliest sinus to develop and be visible radiologically is the Maxillary sinus.

• Largest sinus is the Maxillary sinus.

• Last sinus to develop is the Frontal sinus.

• Most common sinusitis in children is Ethmoidal sinusitis.

• Most common sinusitis in adults is Maxillary sinusitis.

Extra edge Questions

• Q. What is the structure and what all are the foramina related to it?



Ans:
• Medial wall of orbit.
• Crest of bone is Anterior Lacrimal Crest.
• 24 mm behind is Anterior ethmoidal foramen.
• 12 mm behind that is Posterior ethmoidal foramen.
• 6 mm behind that is Optic Canal.

• Q. 27-year-old female with amenorrhea and whitish nipple discharge, taking cabergoline for a benign brain tumor. The surgeon decides to remove it. Which sinus gives access?
• A. Maxillary sinus
• B. Frontal sinus
• C. Ethmoid sinus
• D. Sphenoidal sinus
Ans.
• D. Sphenoidal sinus.
• This is prolactinoma/pituitary adenoma.

• Q. 20-year-old male with nosebleed. Inspection shows bleeding on the nasal floor in the anterior septum. The source terminal branches are from what vessel?
• A. Superior labial artery
• B. Anterior ethmoidal artery
• C. Internal maxillary artery
• D. Sphenopalatine artery
Ans.
• A. Superior labial artery.
• Branch of Facial Artery.
• Supplies anteroinferior septum and floor of nose.

• Q. 25-year-old man for sphenoethmoidal air cell (Onodi cell) operation. What is the blood supply of the structure at high risk for injury?
• A. Middle cerebral artery
• B. Superficial temporal artery
• C. Central retinal artery
• D. Facial artery
Ans.
• C. Central retinal artery.
• Structure at risk is the Optic nerve.
• Blood supply is the Central retinal artery.

• Q. The foramen shown is



• A. Superior orbital fissure
• B. Inferior orbital fissure
• C. Optic canal
• D. Anterior ethmoidal canal
Ans.
• C. Optic Canal.



 

• Q. The foramen shown is:



• A. Sphenopalatine foramen
• B. Greater palatine foramen
• C. Inferior orbital fissure
• D. None
Ans.
• A. Sphenopalatine foramen (sphenopalatine artery passes through).

• Q. The artery present in this fossa is:



• A. Ethmoidal artery
• B. Internal maxillary artery
• C. External carotid artery
• D. Facial artery
Ans.
• B. Internal maxillary artery.
• Pterygopalatine fossa is shown; artery is Internal Maxillary Artery.

• Q. The arrow represents
• A. Aggarnasi
• B. Onodicell
• C. Haller cell
• D. Bulla ethmoidalis
Ans.

• C. Haller cell.

• Cell inferomedial to the orbit is the Haller cell.