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

What are the functions of the nose and nasal cavity?

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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What doe the nasal cavity involve?

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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what are the two apertures in the nasal cavity

anterior nasal aperture(nostril)

posterior nasal aperture(choanae)

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What makes up the external nose?

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

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

the prominence of it

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

usually a lot of swelling

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What is the vestibule of the nose ?

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

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What is the vestibule lined with?

skin containing sebaceous/ sweat glands and hair

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What is the functions of the hairs in the vestibule?

Filters large molecules in inspired air

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What forms the boundaries of the nasal cavity?

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

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

Conchae/turbinates

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

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What are the spaces under the conchae called?

Meatuses

• Superior • Middle • Inferior

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What is the functions of the turbinates/conchae?

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

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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which bones make up the roof of the nasal cavity?

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

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

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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What makes up the septum?

Perpendicular plate of ethmoid bone, vomer bone and cartilage

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Where does the cartilage of nose receive blood supply from?

Cartilage is avascular, relies on overlying perichondrium for blood supply

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What is a septal haematoma?

Blood between the septal cartilage and its perichondrium

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What can cause septal haematoma?

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

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

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

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How can a septal haematoma be identified?

look up into nose to look fro septal swelling

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What carries general sensation from the nasal cavity?

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

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

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

What does the olfactory mucous membrane contain?

dendrites of olfactory nerves

where is the olfactory region?

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

What are the cells of the respiratory mucous membrane?

Pseudostratified columnar ciliated epithelium rich in goblet cells

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

- Filters (mucous/cilia) - Humidifies (watery secretions) - Warms (rich blood supply)

What are nasal polyps and how do they appear?

Fleshy, Benign Swellings of Nasal Mucosa | - Pale or yellow in appearance/fleshy and reddened

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

Usually bilateral, and common in >40yrs | not common in children

What are the symptoms of nasal polyps?

- 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

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

tumour

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

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

What is rhinitis?

inflammation of the nasal mucosa

What are the symptoms of rhinitis?

- Nasal congestion - Rhinorrhoea ("runny"nose) - Sneezing - Nasal irritation - Postnasal drip - mucosal secretion run down into nasopharynx and oroharynx leading to cough

What are common causes of rhinitis?

- Simple acute infective rhinitis (viral- the common cold!) | - Allergic rhinitis (pollen)

Why is rich blood supply to the nasal mucosa important?

Allow for warming and humidification of air

What is the term for nose bleed?

epistaxis

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

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

Which arteries contribute to the Kiesselbach's plexus?

Ophthalmic: anterior ethmoidal Maxillary: Sphenopalatine and greater palatine

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

Sphenopalatine artery from maxillary, more difficult to treat.

What is the Venous drainage from nasal cavity?

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

How is epistaxis from Kiesselbach’s plexus treated?

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

Why are nose bleeds common?

Mucosa and blood vessels easily injured

What are the paranasal sinuses?

Air filled spaces that are extensions of nasal cavity

What are the paranasal sinuses lined with?

respiratory muscosa (thus are also ciliated and secrete mucous)

What is the function of the paranasal sinuses?

- help humidify and warm inspired air | - reduce weight of the skull

where do the paranasal sinuses drain into?

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

Which paranasal sinus is most commonly affected in sinusitis?

maxillary sinus

What are the 4 different paranasal sinuses?

frontal, maxillary, sphenoidal and ethmoidal

What are the important anatomical relations of the paranasal sinuses?

nasal cavity, orbit and anterior cranial fossa

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

dental infection can sometimes spread to paranasal air sinus

What is general sensory innervation of the paranasal sinuses?

* Frontal, ethmoidal and sphenoid = Va | * Maxillary = Vb

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

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

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

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

What is the treatment for sinusitis?

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

What is the pathophysiology of acute sinusitis?

- 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

Why is the maxillary sinus most common in sinusitis?

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

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

Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis

What history of acute sinusitis may indicate bacterial infection?

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