Anatomy and Physiology of
Nose and Paranasal Sinuses
Dr. Krishna Koirala
2019-11-05

External Nasal Framework
• Nasal Bone
• Frontal Process of Maxilla
• Upper Lateral Nasal
Cartilage
• Lower Lateral Nasal (Alar)
Cartilage
• Septal Cartilage
• Lesser Alar (Sesamoid)
Cartilages

Internal Nose
• Openings : Anterior and posterior nares
• Vestibule of nose : lined by skin ,contains hair
follicles
• Nasal cavity proper : Lateral Wall , Medial Wall
(Septum) , Roof , Floor

1. Septal cartilage
2. Ethmoid plate
3. Vomer
4. Palatine crest
5. Maxillary crest
6. Vomeronasal cartilage
7. Medial alar crus
8. Upper lateral cartilage
9. Nasal bone crest
10. Frontal spine
11. Sphenoid rostrum
12. Membranous septum
Nasal Septum

Lateral Nasal Wall
• Vestibule of nose : lined by skin ,contains hair follicles
• 3 - 4 bony conchae are covered with mucosa to form
the turbinates
• Space below and lateral to turbinate is called meatus
• Middle meatus contains a round bulla ethmoidalis
separated from uncinate process by hiatus
semilunaris that leads to a funnel shaped ethmoidal
infundibulum

Meatal Drainage
1. Inferior meatus:
Nasolacrimal duct
2. Middle meatus: Frontal ,
anterior ethmoid , maxillary
3. Superior meatus : Posterior
ethmoid
4. Spheno - ethmoidal recess:
Sphenoid

Ostio -meatal Complex
• Complex micro-architectural
pathway in ethmoid labyrinth that
drains anterior group of paranasal
sinuses
• Consists of
– Frontal recess , ethmoid
infundibulum, hiatus
semilunaris, uncinate process,
bulla ethmoidalis, middle
meatus
• O.M.C. pathology leads to infection
of all anterior paranasal sinuses
(Naumann)

O.M.C. Variants
• Concha bullosa (pneumatized middle turbinate)
• Paradoxically curved middle turbinate
• Medially turned (bent) uncinate process
• Large bulla ethmoidalis
• Agger nasi cell (anterior to middle turbinate)
• Haller’s cell (orbital floor)
• Mucosal pathology

Concha Bullosa

Paradoxically curved M.T.

Large bulla ethmoidalis

Blood Supply
1. Sphenopalatine artery (main artery)
2. Greater palatine artery
3. Superior labial artery
4. Anterior Ethmoidal artery
5. Posterior Ethmoidal artery
1, 2, 3 & 4 form Kiesselbach’s plexus over Little’s
area on anterior septum

Blood supply of Nasal septum

Blood supply of lateral nasal wall

Venous Drainage
• Ethmoidal veins ophthalmic veins  cavernous sinus
• Sphenopalatine vein  pterygoid plexus  maxillary
vein
• Woodruff’s venous plexus : present on lateral wall
near the posterior end of middle turbinate
• Retro - columellar vein: behind the columella

Autonomic Nerve Supply
• Deep petrosal nerve (sympathetic) + greater superficial
petrosal nerve (parasympathetic)  Vidian nerve  pterygo-
palatine ganglion  nasal glands
• Sympathetic stimulation  vasoconstriction + ed nasal
secretions
• Para-sympathetic stimulation  vasodilatation + ed nasal
secretions

• Lining Epithelium
– Skin: on the nasal vestibule
– Olfactory epithelium: upper 1/3rd of nasal cavity above the
superior turbinate
– Respiratory epithelium (pseudo-stratified ciliated columnar)
: rest of nasal cavity + paranasal sinus
• Lymphatic Drainage:
– External nose & anterior nasal cavity : Submandibular LN
– Remaining nasal cavity : Upper deep cervical lymph nodes
– Nasal roof (dangerous area of nose) : Subarachnoid space
along the olfactory nerve
– P.N.S. : Retropharyngeal & J.D. node

Paranasal Sinuses
• Anterior group
– Frontal
– Anterior ethmoidal
– Maxillary
• Posterior group
– Posterior ethmoidal
– Sphenoid

Development of P.N.S.
Appear
first
First X-ray
appearance
Reach adult
size by
Maxillary At birth 4 mth 15 yr
Ethmoidal At birth 1yr 12 yr
Sphenoid 2 yr 4 yr 18 yr
Frontal 4 yr 6 yr 15 yr

Physiology of Nose & PNS,
Olfaction

Functions of Nose
• Respiration
– Heat exchange
– Humidification
– Filtration
– Nasal resistance
– Nasal fluids & cilliary
function
– Nasal neurovascular reflexes
– Voice modification
• Olfaction
Functions of PNS

Respiration
• Inspiration
– Air current passes along mid-
portion of nasal cavity in lamellar
flow
• Expiration
– Resistance of nasal valve &
turbinates leads to formation of
eddy current in expired air
– Results in awareness of breathing
and ventilation of paranasal sinus

Air conditioning
• Filtration : Particles > 3 μm in inspired air are trapped
by nasal vibrissae
• Temperature control
– Heat exchange between blood in cavernous venous
sinusoids of turbinates and inspired air (radiation)
• Humidification
– secretions of nasal & PNS mucosa; for better ciliary
function

Protection of lower airway
• Muco-ciliary blanket : traps pathogens in inspired air
> 0.5 μm & transports them to nasopharynx for
swallowing
• Sneezing : protects against irritants
• Lysozyme : kills bacteria & viruses
• Immunoglobulins A & E : protection against bacteria
• Interferon : for protection against virus

Muco-ciliary blanket
• Goblet cells in nasal mucosa
secrete a mucous blanket
that moves backwards like a
conveyer belt into the
nasopharynx
• Consists of superficial
mucous or gel layer and
deep serous or sol layer

Factors decreasing mucociliary function
• Dry atmosphere (absence of humidity)
• Smoking, air pollutants , nasal irritants
• Infection
• Extremes of temperature
• Hypoxia
• Drugs: anesthetics, sedatives, beta blockers, topical
nasal decongestants

Ventilation of PNS
• Inspiration
– Negative pressure created in
nasal cavity sucks out air
from paranasal sinuses via
their ostium
• Expiration
– Eddies within nasal cavity
create positive pressure that
ventilates paranasal sinuses
via their ostium

Drainage of the sinuses
• Anterior sinuses drain in lateral pharyngeal gutter
• Posterior sinuses drain over posterior pharyngeal wall

Nasal resistance
Nasal resistance to expired air
(by nasal valve) keeps positive
pressure in respiratory tract &
prevents alveolar collapse

Vocal Resonance
• Nasal cavity & paranasal sinuses provide vocal
resonance for nasal consonants M, N, nG
• De-nasal voice( Hyponasal Voice)
– Seen in nasal obstruction
– Nasal consonants M, N & nG pronounced as B, D
& G respectively

Nasal Reflexes
• Smell reflex : Increases secretions of saliva & gastric
juice
• Naso-pulmonary reflex : Chronic, severe nasal
obstruction leads to increased pulmonary resistance
and pulmonary hypertension
• Sneeze reflex : Protection against F.B., irritants

Nasal Cycle
• Reflex, periodic alternation in nasal airflow resistance
between two nasal cavities
• Regulated by autonomic nervous system
• Due to congestion & decongestion of venous
sinusoids of inferior turbinates & anterior nasal
septum
• Each cycle lasts for 4 -12 hours

Factors modifying nasal cycle
• Temperature & humidity of surrounding air
• Head position
• Body temperature
• Physical activity
• Emotional & psychological status
• Hypothyroidism & hyperthyroidism
• Nasal decongestants & anti- hypertensives

Olfaction

Olfactory area of nose
• Located on the roof of
the nasal cavity
– Cribriform plate
– Superior part of the
nasal septum
– Superior turbinate
– Upper part of middle
turbinate

Olfactory neural pathway
Olfactory receptors on nasal mucosa  Olfactory nerve
bundles (20)  synapse with Mitral & Tufted cells in
Olfactory bulb  Axons unite to form Olfactory tract 
flattens distally to form Olfactory trigone  trifurcates
into Olfactory striae  synapse with 10
& 20
Olfactory
cortex + hypothalamus + hippocampus + amygdala

• Olfaction is the only sensation to reach cerebral
cortex directly without first relaying at thalamus
• Olfactory pathway incorporates limbic system & is
concerned with emotional behaviour, mood & recent
memory

Causes of Olfactory dysfunction
1 . Upper respiratory viral infection (30 %)
2. Idiopathic (25 %)
3. Head trauma (20 %)
4. Obstructive sinonasal disease (15 %) : Rhino –sinusitis , nasal
polyp , neoplasm
5. Neurologic & Psychiatric diseases
6. Intra-cranial neoplasm
7. Toxic chemicals & surgical trauma

Classification
• Conductive loss: obstruction of nasal passages
– Chronic nasal inflammation, polyposis
• Sensorineural loss: damage to neuroepithelium
– Viral infection, airborne toxin
• Central olfactory neural loss: C.N.S. damage
– Tumors, neurodegenerative disorders

Types of Olfactory dysfunction
1. Anosmia: absence of olfactory sensation
2. Hyposmia: decreased olfactory sensation
3. Parosmia / cachosmia: perception of a pleasant
odour as unpleasant odour
4. Phantosmia: perception of odour in absence of
olfactory stimulus
5. Hyperosmia: increased olfactory sensation
6. Olfactory agnosia: unable to identify odour

Olfactory function tests
1. Supra-threshold test: only identifies odour
– Smell bottles
– Smell Identification Test (S.I.T.)
2. Threshold Olfactometry: measures weakest
perceptible odour with help of serial dilution
– Manual
– Dynamic (automated)

Manual Threshold Olfactometry

Dynamic Threshold Olfactometry

University of Pennsylvania Smell
Identification Test (UPSIT)
• Most commonly used test of smell worldwide
• 4 booklets of 10 microencapsulated odors stimuli
• Scratch and sniff format
• Four responses accompanying each odor
• Forced choice design
• Scores are compared to normal (sex- and age-related)

Smell Identification Test sample

Results
36 – 40 : Normal
16-35 : Partial anosmia
6-15 : Total anosmia
0-5 : Malingering