S9) Functional Anatomy of the Nose, Nasal Cavity and Paranasal Sinuses

Question 1

Describe the anatomical location of the nasal cavity

Answer 1

The nasal cavity extends from the anterior nasal aperture (nostrils) to the posterior nasal aperture (choanae)

Question 2

Identify 5 functions of the nose and nasal cavity

Answer 2

• Sense of smell
• Route for inspired air
• Filters inspired air (nasal hair/mucous)
• Moistens and warms inspired air
• Resonating chamber for speech

Question 3

Identify and describe the two components of the external nose

Answer 3

• Bony component – nasal bone and frontal process of maxilla
• Cartilaginous component – two lateral cartilages, two alar cartilages and one septal cartilage

Question 4

What is the most commonly fractured bone of the facial skeleton?

Answer 4

Nasal bone (due to prominence)

Question 5

How does inspired air enter the nasal cavity?

Answer 5

Inspired air enters via the vestibule which is the area surrounding the anterior external opening to the nasal cavity

Question 6

What lines the surface of the vestibule (of the external nose)?

Answer 6

• Skin
• Hairs

Question 7

What sort of membrane lines the nasal cavity?

Answer 7

Olfactory and respiratory mucous membranes

Question 8

What sort of epithelium is found in the respiratory mucous membrane?

Answer 8

Pseudostratified columnar ciliated epithelium

Question 9

What are the actions of the respiratory mucosa?

Answer 9

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

Question 10

Which structures drain into the nasal cavity?

Answer 10

• Paranasal sinuses
• Nasolacrimal duct (drains eye)

Question 11

What are the different boundaries of the nasal cavity?

Answer 11

Question 12

Which structures forms the floor of the nasal cavity?

Answer 12

The hard palate

Question 13

Describe the structure of the lateral wall of the nasal cavity

Answer 13

Bony projections — inferior conchae, middle conchae, superior conchae

Question 14

Explain how the structure of the lateral wall of the nasal cavity is adapted to its functions

Answer 14

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

Question 15

Which physical features of the nasal cavity allow for the slowing of inspired air?

Answer 15

• Movement from narrow vestibule to large nasal cavity
• Conchae offer more resistance and disturbs the laminar flow of air

Question 16

Which three structures form the roof of the nasal cavity?

Answer 16

Question 17

Which two structures form the medial wall of the nasal cavity?

Answer 17

Question 18

Describe the blood supply of the cartilaginous part of the nasal septum

Answer 18

Cartilaginous part of septum takes blood supply from overlying perichondrium

Question 19

Why should one always examine for septal haematomas in patients presenting with nasal injury?

Answer 19

• Trauma to nose can buckle the septum and shear blood vessels
• Blood accumulates between perichondrium and cartilage

Question 20

What is a saddle nose deformity?

Answer 20

A saddle nose deformity is a condition due to an untreated septal haematoma which leads to avascular necrosis of cartilaginous septum

Question 21

Besides saddle nose deformity, what is another complication of untreated septal haematoma?

Answer 21

An infection in the collecting haematoma can develop and the septal abscess formation further increases likelihood of avascular necrosis of septum

Question 22

Which cranial nerve carries general sensation from the nasal cavity?

Answer 22

Trigeminal nerve

Question 23

What are nasal polyps?

Answer 23

• Nasal polyps are fleshy, benign swellings of nasal mucosa which are usually pale/yellow and reddened
• They are usually bilateral and are common >40 years

Question 24

Identify 5 symptoms of nasal polyps

Answer 24

• Blocked nose
• Watery rhinorrhoea
• Post-nasal drip
• Decreased smell
• Reduced taste

Question 25

What is rhinitis?

Answer 25

**Rhinitis** is the inflammation of the nasal mucosal lining

Question 26

Identify 5 symptoms of rhinitis

Answer 26

- Nasal congestion - Rhinorrhoea (“runny” nose) - Sneezing - Nasal irritation - Postnasal drip

Question 27

Identify two of the commonest causes of rhinitis

Answer 27

- Simple acute infective rhinitis (common cold) - Allergic rhinitis

Question 28

Nasal mucosa and blood vessels easily injured. What is the result?

Answer 28

Epistaxis (nosebleed)

Question 29

Describe the arterial supply of the nasal cavity

Answer 29

- **Anterior** & **posterior** **ethmoidal** arteries (branch of ophthalmic artery) - **Sphenopalatine** artery (branch of maxillary artery)

Question 30

What is Kiesselbach's plexus?

Answer 30

**Kiesselbach’s plexus** (Little's area) is an area of arterial anastomoses in the anterior nasal septum (most common source of bleeding in epistaxis)

Question 31

Describe the venous drainage of the nasal cavity

Answer 31

**Venous drainage** into pterygoid venous plexus, cavernous sinus and facial vein

Question 32

What is significant about bleeding from the sphenopalatine artery in the nasal cavity?

Answer 32

- Bleeding from the **sphenopalatine artery** is source for small minority of nosebleeds - It is potentially more serious and difficult to treat (posterior & high pressure)

Question 33

What are the paranasal sinuses?

Answer 33

The **paranasal sinuses** are air filled spaces that are extensions of nasal cavity (rudimentary/absent at birth)

Question 34

Identify the 4 different paranasal sinuses

Answer 34

Question 35

Describe the structure and function of the paranasal sinuses

Answer 35

**- Structure**: lined with respiratory mucosa (ciliated) - **Function**: secrete mucous, help humidify and warm inspired air, reduce weight of the skull

Question 36

Describe the drainage of the paranasal sinuses

Answer 36

All drain into the nasal cavity via small channels called **ostia** into a meatus (mostly middle meatus)

Question 37

Identify the important anatomical relations of the paranasal sinus

Answer 37

- Nasal cavity - Orbit - Anterior cranial fossa

Question 38

Describe the specific sensory innervation to the different paranasal sinuses

Answer 38

- Frontal, ethmoidal and sphenoid sinuses ⇒ **CN V_a** - Maxillary sinus ⇒ **CN V_b**

Question 39

In the X-ray below, label the following: - Frontal sinuses - Orbit - Ethmoid air cells - Nasal cavity - Floor of orbit

Answer 39

Question 40

In the X-ray below, label the following: - Maxillary sinuses - Zygoma - Zygomatic process - Mandible

Answer 40

Question 41

In the diagram below, identify the four paranasal sinuses

Answer 41

Question 42

Which sinuses are visible lying in close proximity to the medial wall of the orbits?

Answer 42

Question 43

Infections in nasal cavity can involve sinuses (sinusitis). Which is the most commonly affected paranasal sinus?

Answer 43

**Maxillary sinus** most commonly affected

Question 44

What is acute sinusitis?

Answer 44

**Acute sinusitis** is the acute inflammation of the lining of the sinus which is commonly infective and often secondary to the viral infection of nasal cavity (common cold)

Question 45

Identify 5 signs and symptoms of acute sinusitis

Answer 45

- Non-resolving cold - Pyrexia - Blocked nose - Rhinorrhoea (± green/yellow discharge) - Headache/facial pain (area of affected sinus)

Question 46

Why might a patient with sinusitis complain of toothache?

Answer 46

- **Roots** of upper teeth can sometimes project into maxillary sinus - Pain in the maxilla/maxillary sinus can **radiate** to oral cavity

Question 47

Outline the pathophysiology of acute sinusitis

Answer 47

- Primary infection *e.g. rhinitis* leads to reduced **ciliary** function, **oedema** of nasal mucosa and sinus ostia and increased nasal **secretions** - **Drainage** from sinus is impeded and **secondary bacteria** breed in stagnant secretions

Question 48

Identify some important anatomical relations of the nasal cavity

Answer 48

- Paranasal sinus - Sphenoid bone - Orbit - Nasopharynx - Oral cavity

Question 49

What is epistaxis?

Answer 49

**Epistaxis** is the common occurrence of bleeding from the nose

Question 50

What are some causes for epistaxis?

Answer 50

- Occur spontaneously - Very minor trauma - Abnormal coagulation - Connective tissue disorders

Question 51

Which groups of patients commonly present with epistaxis?

Answer 51

- Very young (2-10 years) - Old (\> 50-60 years)

Question 52

Outline the 6 steps in the management of epistaxis

Answer 52

⇒ Apply simple compression (cartilage) ⇒ Lean forward ⇒ Cauterisation ⇒ Anterior packing with nasal tampons ⇒ Posterior packing with nasal tampons ⇒ Surgical intervention *e.g. embolisation, ligation of blood vessels*