1. Physiology of Nose & P.N.S.
Dr. Vishal Sharma

2. Functions of nose Respiration Air conditioning of inspired air
Protection of lower airway
Ventilation & drainage of P.N.S.
Olfaction: increased on sniffing
Nasal resistance
Vocal resonance
Nasal reflexes

3. Functions of P.N.S. (?) Air conditioning of inspired air
Vocal resonance
Thermal insulators for orbit & cranium from fluctuating nasal temperature
Lightens weight of skull

4. 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.
This results in awareness of breathing & ventilation of paranasal sinus.

5. Respiration

6. Air conditioning
Filtration: particles > 3 μm in inspired air are trapped by nasal vibrissae
Temperature control: Heat exchange b/w blood in cavernous venous sinusoids of turbinates & inspired air, by radiation
Humidification: by secretions of nasal & P.N.S. mucosa; for better ciliary function

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

8. Muco-ciliary blanket
Goblet cells in nasal mucosa secrete a mucous blanket; moved backwards like a conveyer belt into nasopharynx.
Consists of:
 Superficial mucous or gel layer
 Deep serous or sol layer

9. Muco-ciliary blanket

10. Muco-ciliary blanket

11. Ciliary cycle

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

14. Ventilation of P.N.S.
Inspiration: negative pressure created in nasal cavity  sucks out air from paranasal sinuses via their ostium.
Expiration: eddies within nasal cavity create positive pressure  ventilates paranasal sinuses via their ostium.

15. Ventilation of P.N.S.

16. Drainage of sinuses

17. Drainage of sinuses
Anterior sinuses drain in lateral pharyngeal gutter
Posterior sinuses drain over posterior pharyngeal wall

18. Drainage of sinuses

19. Nasal resistance
Nasal resistance to expired air keeps positive pressure in respiratory tract & prevents alveolar collapse

20. Nasal Resistance Nose provides 50-60 % of total airway resistance
Nasal resistance is provided by 3 areas:
Nasal vestibule
Nasal valve (maximum contribution)
Nasal turbinates

21. Nasal valve
Anterior nasal valve (ostium internum) is located at limen nasi, 1.5 cm posterior to anterior nares. Consists of inferior margin of upper lateral nasal cartilage + anterior end of inferior turbinate + adjacent nasal septum. Cross-section of airway here is mm2 on each side. It is narrowest part of upper respiratory tract. Cottle’s test checks valve patency.

26. Vocal resonance
Nasal cavity & paranasal sinus cavity provide vocal resonance for nasal consonants M, N & nG
De-nasal voice is seen in nose block. Nasal consonants M, N & nG are uttered as B, D & G respectively

27. Nasal reflexes 1. Smell reflex: increases secretions of
saliva & gastric juice
2. Naso-pulmonary reflex: Chronic, severe nasal obstruction  increased pulmonary resistance  pulmonary hypertension
3. Sneeze reflex: protection against F.B.

28. Nasal Cycle

29. Nasal Cycle
Reflex, periodic alternation in nasal airflow resistance b/w 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 2-12 hrs (average 2-4 hrs)

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

32. Olfactory area of nose

33. Olfactory neural pathway
Olfactory receptors on nasal mucosa  20
Olfactory nerve bundles  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.

34. Olfactory neural pathway

35. Olfactory neural pathway

36. Olfactory neural pathway
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

37. Olfactory dysfunction causes
1. Upper respiratory viral infection (30 %)
2. Idiopathic (25 %)
3. Head trauma (20 %)
4. Obstructive sino-nasal disease (15 %)
 Rhino-sinusitis  Nasal polyp / neoplasm
5. Neurologic & Psychiatric diseases
6. Intra-cranial neoplasm
7. Toxic chemicals & surgical trauma

38. 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

39. Olfactory dysfunction types
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

40. Tests for olfactory disorders
1. Tests for nasal airflow
a. Simple Rhino-manometry: anterior & posterior
b. Acoustic Rhino-manometry: uses sound waves
2. Tests for ciliary function
a. Saccharine test
3. Tests for olfaction
4. CT scan & MRI of PNS & brain

41. Rhino-manometry
Test of nasal function, measures air pressure & rate of nasal airflow during respiration. These are used to calculate nasal airway resistance.
anterior rhino-manometry: pressure sensor placed at tip of each nostril in turn.
posterior rhino-manometry: pressure sensor (small plastic tube) placed behind nasal cavity.

43. Anterior Rhino-manometry

44. Posterior Rhino-manometry

45. Rhinogram

46. Acoustic rhino-manometry

47. Saccharin Test Evaluates ciliary function by
measuring time taken for a
drop of saccharin to be tasted
in throat when applied to
inferior turbinate (anterior tip).
Normal speed = 5-10 mm / min.
Normal time = min.

48. 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 (automatic)

49. University of Pennsylvania Smell Identification Test
U.P.S.I.T. consists of 4 test booklets, each
containing 10 stimuli for smell. All 40 stimuli are
presented in rectangular areas. Subjects scratch
& then sniff them. They are required to pick 1
from 5 multiple choices present for each stimuli.

50. 36 - 40  normal; 16 - 35  partial anosmia
 total anosmia;  malingering

52. Hyposmia or anosmia
Nasal block  treat nasal disease
Upper respiratory tract infection  medical tx
Old age  counseling
Head trauma  Neurosurgical referral
Smoking  quit smoking
Toxin exposure  avoid exposure
Congenital  Endocrine referral
Parosmia
with seizures  Neurology referral
psychiatry symptoms  Psychiatry referral

53. Counseling & Precautions
1. Beware of the following:
Spoiled food
Explosive gases: use electric stoves
Smoke & fire: use detectors with visual alarms
Socially unacceptable odors
2. Food enjoyment: flavor additives

54. Thank You