Anatomy of the nose, nasal cavities and paranasal sinuses

Question 1

What structures make up the external nose?

Answer 1

Cartilage and Bone (nasal bone and maxilla)

Question 2

What is the vestibule of the external nose lined with?

Answer 2

• Skin containing sebaceous / sweat glands
• Hair

Question 3

What are the boundaries of the nasal cavity?

Answer 3

Roof: Cribiform palate

Floor: Hard Palate

Medial wall: nasal septum

Question 4

What are the projections that come out of the lateral wall of the nasal cavity and what is their function?

Answer 4

Projections = bony conchae (Superior, Middle and Inferior)

Meatus= spaces between projections

Function: Slows airflow by causing turbulent airflow

Increases surface area over which air passes

Question 5

What lines the lateral wall of the nasal cavity?

Answer 5

Respiratory epthelium

Question 6

Why does your nose run when crying?

Answer 6

Tears from the lacrimal gland spill into the nasal cavity

Question 7

Which meatus of the nasal cavity do the paranasal air sinuses open into?

Answer 7

Middle Meatus

Question 8

What components make up the nasal septum?

Answer 8

A bony and cartilaginous part:

Bone: Vomer bone and Perpendicular plate (of ethmoid bone)

Cartilage: Septal cartilage

Question 9

Where does the nasal cartilage recieve its blood supply from?

How can this be problematic in injury to the nose?

Answer 9

Nasal cartilage recieves blood supply from overlying perichondrium

Injury to nose can buckle the septum, shearing blood vessels →blood accumulates in subperichondrium →septal haematoma → underlying cartilage deprived of blood supply

Question 10

How would you treat a septal haematoma?

Answer 10

By tamponade

Drain the haematoma and apply cotton wool forcing the perichondrium back onto cartilage

Question 11

What is the consequence of an untreated sepatal haematoma and why does this happen?

Answer 11

Saddle Nose Deformity

Untreated haematoma causes avascular necrosis of septal cartilage

Haematoma is also a site for infection which further increases changes of avascular necrosis

Question 12

Which cranial nerve carries general sesnation from the nasal cavity?

Answer 12

Trigeminal (Maxillary Vb branch)

Question 13

The nasal cavity is lined with 2 mucus membranes, describe the 2 membranes and the function of each

Answer 13

1. Olfactory mucus membrane - houses Olfactory receptor neurones for sense of smell (CN1)
2. Respiratory mucus membrane - pseudostratified columnar ciliate epithelium, rich in goblet cells
   
   • filters air (mucus and cilia)
   • Humidifies air (watery secretions)
   • Warms air (rich blood supply)

Question 14

What are nasal polyps and what do they look like?

Answer 14

Fleshy, benign swellings of nasal mucosa

Can be pale or yellow and are fleshy in appearance (can be reddened)

Question 15

Are nasal polys usually bilateral or unilateral?

Answer 15

Bilateral

If unilateral and blood tinged this is more concerning - may suggest a tumour

Question 16

What symptoms do you get with a nasal polyp?

Answer 16

• Blocked nose
• watery rhinorrhoea
• Post nasal drip (down the back of the throat)
• Decreased smell and reduced taste

Question 17

What is rhinitis and what are the main symptoms?

Answer 17

Inflammation of the nasal mucosal lining

Symptoms:

• nasal congestion
• Rhinorrhoea
• Sneezing
• Nasal Irritation
• Postnasal drip

Question 18

What are the common causes of rhinitis?

Answer 18

• simple acute infective- viral
• allergic

Question 19

What is epistaxis?

Answer 19

Nose bleed

Question 20

Why is the nose so vascular?

Answer 20

To allow for warming and humidification of inspired air

Question 21

Which arteries supply the nasal cavity?

What is the most common source for bleeding in epistaxis?

Answer 21

Branches of opthalmic and maxillary arteries

Anastamoses in the anterior septum form Kiesselbach’s plexus (or Little’s area)- the main site for nose bleeds

Question 22

What is the the venous drainage of the nasal cavity?

Answer 22

Pterygoid venous plexus

(also drains to cavernous sinus and facial vein)

Question 23

Bleeding from which artery in the nose is not easily treatable by first aid and may require surgery to ligate?

Answer 23

Bleeding from Spehnopalatine artery (a branch of maxillary)

At the posterior of the nasal cavity so cannot be reached by tamponade

Question 24

What are paranasal air sinuses and what is their function?

Answer 24

Air filled spaces that are extensions of the nasal cavity

Function: humidify and warm inspired air and help reduce weight of skull

Question 25

Which type of mucusa lines paranasal sinuses?

Answer 25

**respiratory mucosa**

Question 26

How do paranasal sinuses drain into the nasal cavity?

Answer 26

Drain by a small channel called **ostia** into a meatus (most commonly **middle meatus**)

Question 27

Identify the paranasal air sinuses

Answer 27

Question 28

Which nerves recieve general sensory innervation from the paranasal air sinuses?

Answer 28

Frontal, ethmoid and sphenoid → Trigeminal Opthalmic division (Va) Maxillary → Trigeminal Maxillary division (Vb)

Question 29

What is acute sinusitis?

Answer 29

**Symptomatic inflammation of mucosal lining** of the nasal cavity and paranasal air sinuses Often secondary to a **viral infection** of the nsal cavity

Question 30

What are some of the symptoms of acute sinusitis?

Answer 30

* Recent URTI * Blocked nose and rhinorrhoea +/- green/ yellow discharge * Pyrexia * Headache / facial pain worse on _leaning forwards_

Question 31

How do you treat acute sinutisis?

Answer 31

Mostly self limiting Use analgesics, antipyretics and steam inhalation to treat symptoms

Question 32

Explain why a primary infection can lead to acute sinusitis?

Answer 32

* Primary infection causes **reduced ciliary function**, **increased nasal secretions** and **oedema** of nasal mucosa * Therefore **drainage** from the nasal sinuses is **impeded** * **Stagnant secretions** allow bacterial growth for a second infection

Question 33

Which bacteria most commonly cause acute bacterial sinusitis?

Answer 33

* *Streptococcus pneumonia* * *Haemophilus Influenzae* * *Moraxella Catarhalis*

Question 34

Why is the **maxillary sinus** the most commonly affected paranasal air sinus?

Answer 34

It's **ostia** is located high on the wall of the nasal cavity therefore drainage from the sinus is harder

Question 35

Why is a rare, but serious consequence of **ethmoidal** sinus infection, sight threatening?

Answer 35

1. Infection in air cells of ethmoid sinus can break through the **thin, medial** wall of the **orbit** 2. Infection can spread to the orbit causing orbital cellulitis 3. Infection sight threatening as it may involve the **optic nerve** or track back to involve **intracranial structures**

Question 36

What is a serious, but rare **intracranial complication** of sinutsitis? Explain how with reference to the anatomy of venous drainage of the sinuses

Answer 36

**Cavernouse Sinus Thrombosis** * Secondary from infection spreading from the nose through the anastamosis of venous dranage from nasal mucosa/ sinuses to cavernous sinus

Question 37

What structures can be affected as a result of cavernous sinus thrombosis?

Answer 37

Any structure running through the cavernous sinus: * Occulomotor nerve * Abduscens nerve * Trochlear nerve * Opthalmic division of the trigeminal * Maxillary Division of the trigeminal * Internal Carotid * Sympathetic plexus surrounding the carotid artery