Anatomy and physiology of nose and PNS

1. Anatomy and
Physiology of
Nose and
Paranasal Sinuses
Dr. Krishna Koirala

2. External Nasal Framework

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

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

5. 1. Septal cartilage
2. Ethmoid plate
3. Vomer
4. Palatine crest
5. Maxillary crest
6. Vomeronasal
cartilage
7. Medial alar crus
8. Upper lateral

9. Lateral Nasal Wall
• 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

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

13. Ostio-meatal Complex
Complex micro-architectural pathway in
ethmoid labyrinth that drains anterior

14. • OMC Consists of
–Frontal recess + ethmoid
infundibulum + hiatus semilunaris
+ uncinate process + bulla
ethmoidalis + middle meatus
• O.M.C. pathology leads to infection

15. Variants in O.M.C.
 Concha bullosa (pneumatized M.T.)
 Paradoxically curved middle turbinate
 Medially turned ( bent) uncinate process
 Large bulla ethmoidalis
 Haller’s cell ( orbital floor)
 Agger nasi cell ( anterior to M.T.)
 Mucosal pathology

16. Concha Bullosa

17. Paradoxically curved M.T.

18. Large bulla ethmoidalis

19. 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

23. 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

24. Sensory Nerve Supply
• Long & short Nasopalatine nerves
• Greater palatine nerve
• Infra-orbital nerve branches
• Anterior ethmoidal nerve
• Olfactory nerve

27. Autonomic Nerve Supply
• Deep petrosal nerve (sympathetic) +
greater superficial petrosal nerve (para-
sympathetic) → Vidian nerve → pterygo-
palatine ganglion → nasal glands
• Sympathetic stimulation →
vasoconstriction + ↓ed nasal secretions
• Para-sympathetic stimulation →
vasodilatation + ↑ed nasal secretions

28. Lining Epithelium
• Skin: on the nasal vestibule
• Olfactory epithelium: upper 1/3rd
of
nasal cavity above the superior
turbinate
• Respiratory epithelium (pseudo-

29. Lymphatic Drainage
1. External nose & anterior nasal cavity
⇒ Submandibular lymph nodes
2. Remaining nasal cavity
⇒ Upper deep cervical lymph nodes
3. Nasal roof (dangerous area of nose)
⇒Subarachnoid space along the
olfactory nerve

30. Paranasal Sinuses
• Anterior group
• Frontal
• Anterior ethmoidal
• Maxillary
• Posterior group
• Posterior ethmoidal
• Sphenoid

33. Development of P.N.S.
Appear
first
First X-ray
appearanc
e
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

34. Physiology of
Nose & PNS,
Olfaction

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

36. Functions of PNS
• Vocal resonance
• Air conditioning of the inspired air
• Pressure damper
• Reduction of skull weight
• Floatation of skull in water
• Increasing the olfactory area

37. 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

38. Respiration

39. 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 & inspired air,
(radiation)
• Humidification
–secretions of nasal & PNS
mucosa; for better ciliary

40. 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

41. 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
– Deep serous or sol layer

42. Muco-ciliary blanket
Ge
l
Sol

44. Ciliary cycle

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

46. 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

47. Ventilation of PNS

48. Drainage of sinuses

49. • Anterior sinuses
drain in lateral
pharyngeal gutter
• Posterior sinuses
drain over posterior
pharyngeal wall

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

51. 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

52. 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

53. 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

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

55. Olfaction

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

57. 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 +

60. • 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

61. 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

62. 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

63. 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

64. 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)

65. Manual Threshold
Olfactometry

66. Dynamic Threshold
Olfactometry

67. 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

68. Smell Identification Test
sample

69. Results
36 – 40 :Normal
16-35 :Partial anosmia
6-15 :Total anosmia
0-5 :Malingering
Thank you !