14. Anatomy of the Nose, Nasal Cavity Paranasal Air Sinuses Flashcards

1
Q

What are the functions of the nose and nasal cavity?

A
  • Sense of smell
  • Provides a route for inspired air
  • Filters inspired air- trapping particles in nasal hair or mucous
  • Moistens (humidifies) and warms inspired air
  • Resonating chamber for speech
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2
Q

What doe the nasal cavity involve?

A

The nasal cavity extends from the nostrils anteriorly (anterior nasal apertures) to the posterior nasal apertures (also known as choanae) and has a roof, floor and two walls (medial and lateral). It opens into the most superior part of the pharynx, the nasopharynx.

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3
Q

what are the two apertures in the nasal cavity

A

anterior nasal aperture(nostril)

posterior nasal aperture(choanae)

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4
Q

What makes up the external nose?

A

Mostly cartilage, but also bone which forms the root of the nose (nasal bones and frontal processes of the maxillae)

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5
Q

What makes the nasal bone susceptible to fractures in facial injury?

A

the prominence of it

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6
Q

In nasal bone fracture, why is it hard to notice the fracture?

A

usually a lot of swelling

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7
Q

What is the vestibule of the nose ?

A

frontmost part of the nasal cavity, and is enclosed by cartilages.

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8
Q

What is the vestibule lined with?

A

skin containing sebaceous/ sweat glands and hair

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9
Q

What is the functions of the hairs in the vestibule?

A

Filters large molecules in inspired air

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10
Q

What forms the boundaries of the nasal cavity?

A

Lateral wall: maxilla
Medial wall: septum
Floor: hard palate
Roof: cribriform plate

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11
Q

What are the bony projections of the lateral walls called, how many and where do they come from?

A

Conchae/turbinates

  • superior, middle (part of ethmoid bone)
  • and inferior (bone in itself)
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12
Q

What are the spaces under the conchae called?

A

Meatuses

• Superior • Middle • Inferior

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13
Q

What is the functions of the turbinates/conchae?

A
  • Slows airflow by causing turbulence of airflow
  • Increases surface area over which air passes

Both of which means we can better humidify and warm the air

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14
Q

Which ducts drain into the nasal cavity and in which region do they drain?

A

Openings under the meatuses allow for drainage of
• Paranasal air sinuses into nasal cavity
• Nasolacrimal duct into nasal cavity

contents will then just be swallowed

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15
Q

which bones make up the roof of the nasal cavity?

A

nasal bone
frontal bone
ethmoid bone (cribriform plate)
sphenoid bone

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16
Q

What is the advantage of the close relationship with bones of roof of nasal cavity and floor of cranial fossa?

A

Can access structure in floor of cranial fossa through the nasal cavity for surgery - e.g accessing pituitary gland in surgery easier to go through nasal cavity
- Transsphenoidal surgical approach

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17
Q

What makes up the septum?

A

Perpendicular plate of ethmoid bone, vomer bone and cartilage

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18
Q

Where does the cartilage of nose receive blood supply from?

A

Cartilage is avascular, relies on overlying perichondrium for blood supply

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19
Q

What is a septal haematoma?

A

Blood between the septal cartilage and its perichondrium

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20
Q

What can cause septal haematoma?

A
  • Injury to nose can buckle septum and shears blood vessels

* Blood accumulates sub-perichondrium…depriving underlying cartilage of its blood supply

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21
Q

What is the complication of septal haematoma and how does this occur?

A

Untreated septal haematoma leads to avascular

necrosis of cartilaginous septum and fibrosis, leading to a cosmetic distortion called saddle deformity - if

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22
Q

What can develop within the collecting blood in a septal haematoma?

A

Infection, causing a septal abscess further increasing likelihood of avascular necrosis of septum

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23
Q

How can a septal haematoma be identified?

A

look up into nose to look fro septal swelling

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24
Q

What carries general sensation from the nasal cavity?

A

Trigeminal nerve (branches of ophthalmic and maxillary), innervation extends to nasopharynx also

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25
Q

What are the different regions of the nasal cavity and what are they lined by?

A

Vestibule: skin
Respiratory region: respiratory mucous membrane
Olfactory region: olfactory mucus membrane

26
Q

What does the olfactory mucous membrane contain?

A

dendrites of olfactory nerves

27
Q

where is the olfactory region?

A

Covers over roof of nasal cavity (including superior concha/superior part of septum)

28
Q

What are the cells of the respiratory mucous membrane?

A

Pseudostratified columnar ciliated epithelium rich in goblet cells

29
Q

What are the functions of the respiratory mucous membrane and how are they achieved?

A
  • Filters (mucous/cilia)
  • Humidifies (watery secretions)
  • Warms (rich blood supply)
30
Q

What are nasal polyps and how do they appear?

A

Fleshy, Benign Swellings of Nasal Mucosa

- Pale or yellow in appearance/fleshy and reddened

31
Q

Do nasal polys usually occur on one or both sides and in which people are they more common in?

A

Usually bilateral, and common in >40yrs

not common in children

32
Q

What are the symptoms of nasal polyps?

A
  • Blocked nose and watery rhinorrhoea
  • Post-nasal drip (drains backwards into nasopharynx and larynx irritating it and leading to cough)
  • Decreased smell and reduced taste - stops air from reaching rood of nasal cavity and triggering olfactory nerves
33
Q

What may Unilateral polyp +/- blood-tinged secretion suggest?

A

tumour

34
Q

Where are polyps usually found and what is the result of it?

A

middle meatus - more prone to infection as paranasal sinuses drain into nasal cavity through middle meatus

35
Q

What is rhinitis?

A

inflammation of the nasal mucosa

36
Q

What are the symptoms of rhinitis?

A
  • Nasal congestion
  • Rhinorrhoea (“runny”nose)
  • Sneezing
  • Nasal irritation
  • Postnasal drip - mucosal secretion run down into nasopharynx and oroharynx leading to cough
37
Q

What are common causes of rhinitis?

A
  • Simple acute infective rhinitis (viral- the common cold!)

- Allergic rhinitis (pollen)

38
Q

Why is rich blood supply to the nasal mucosa important?

A

Allow for warming and humidification of air

39
Q

What is the term for nose bleed?

A

epistaxis

40
Q

What is the most common source of bleeding in the nose?

A

Kiesselbach’s plexus (anastomoses of arteries from ophthalmic and maxillary arteries) in the anterior septum

41
Q

Which arteries contribute to the Kiesselbach’s plexus?

A

Ophthalmic: anterior ethmoidal
Maxillary: Sphenopalatine and greater palatine

42
Q

What is a source of minority nose bleeds and why are they more serious?

A

Sphenopalatine artery from maxillary, more difficult to treat.

43
Q

What is the Venous drainage from nasal cavity?

A
• Venous drainage from nasal cavity into pterygoid
venous plexus (also drainage to cavernous sinus and
facial vein)
44
Q

How is epistaxis from Kiesselbach’s plexus treated?

A

Easily treatable with simple first aid measure (“pinching nose”)

45
Q

Why are nose bleeds common?

A

Mucosa and blood vessels easily injured

46
Q

What are the paranasal sinuses?

A

Air filled spaces that are extensions of nasal cavity

47
Q

What are the paranasal sinuses lined with?

A

respiratory muscosa (thus are also ciliated and secrete mucous)

48
Q

What is the function of the paranasal sinuses?

A
  • help humidify and warm inspired air

- reduce weight of the skull

49
Q

where do the paranasal sinuses drain into?

A

All drain into the nasal cavity via small channels called ostia into a meatus - Most into middle meatus

50
Q

Which paranasal sinus is most commonly affected in sinusitis?

A

maxillary sinus

51
Q

What are the 4 different paranasal sinuses?

A

frontal, maxillary, sphenoidal and ethmoidal

52
Q

What are the important anatomical relations of the paranasal sinuses?

A

nasal cavity, orbit and anterior cranial fossa

53
Q

What is the effect of the Roots of upper teeth sometimes project in maxillary sinus?

A

dental infection can sometimes spread to paranasal air sinus

54
Q

What is general sensory innervation of the paranasal sinuses?

A
  • Frontal, ethmoidal and sphenoid = Va

* Maxillary = Vb

55
Q

What is acute sinusitis and what does it occur secondary to?

A

Symptomatic Inflammation of Mucosal Lining of Nasal Cavity and Paranasal Air sinuses
- often occurs secondary to viral infection of the nasal cavity

56
Q

What is the typical history and symptoms of a patient with sinusitis? (4)

A
  • Recent URTI
  • Blocked nose and rhinorrhoea +/- green/ yellow discharge
  • Pyrexia
  • Headache/ facial pain (in area of affected sinus)
    • Worse on leaning forward
57
Q

What is the treatment for sinusitis?

A

Self-limiting: treatment is symptomatic (e.g. analgesics, antipyretics, steam inhalation)

58
Q

What is the pathophysiology of acute sinusitis?

A
  • primary infection leads to reduced ciliary function, oedema of nasal and sinus Ostia, and increases nasal secretions
  • drainage from sinus impeded
  • stagnant secretions ideal for bacteria - secondary infection
59
Q

Why is the maxillary sinus most common in sinusitis?

A

drainage of maxillary sinus is upwards so have t work against gravity too

60
Q

What are the most common bacteria causing a secondary infection in acute sinusitis?

A

Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis

61
Q

What history of acute sinusitis may indicate bacterial infection?

A

• Symptoms particularly severe at onset
• Symptoms >10 days without
improvement (but <4 weeks)
• Symptoms that worsen after an initial improvement (suggesting secondary bacterial infection)