Nasal Cavity and Paranasal Sinuses

Question 1

What are the nasal choanae?

Answer 1

Entrance to the nasopharynx at the posterior wall of the nasal cavity

Question 2

What forms the roof of the oral cavity?

Answer 2

Hard and soft palates

Question 3

What is the function of the hard palate?

Answer 3

Separates nasal and oral cavities

Question 4

What are the borders of the nasal cavity?

Answer 4

Roof: Cribriform plate of the ethmoid bone
Lateral walls: concha, palatine bones and maxilla
Medial walls: nasal septum
Inferior wall: hard palate
Anterior wall: nares (nostrils)
Posterior wall: nasal choanae

Question 5

What is the function of the nasal concha?

Answer 5

Warm and humidify air by creating turbulent air flow
Trap particulate matter
Increase the surface area of the nasal cavity

Question 6

What are the meatus?

Answer 6

Spaces underneath nasal concha

Question 7

What are nasal polyps? What causes them and what are the potential complications?

Answer 7

Usually painless, non-cancerous, swollen masses
Can be caused by chronic inflammation
Can cause blockage of the drainage of paranasal sinuses and problems with voice resonation.
Can block the passage of air through the nasal cavity

Question 8

What are the 3 regions of the nasal cavity?

What type of epithelium covers them and what is its function?

Answer 8

Olfactory region: respiratory epithelium (pseudo-stratified ciliated columnar) with olfactory sensory nerve endings to provide sense of smell.

Nasal vestibule: stratified squamous epithelium: helps resist abrasion. Hair bearing: traps particulate matter.

Respiratory region: Pseudo-stratified ciliated columnar epithelium with goblet cells that product mucous. Warms and humidifies inspired air.

Question 9

What bones make up the nasal cavity?

Answer 9

Cartilage forms anterior portion
Ethmoid bone
Vomer
Palatine bones
Maxillary bones
Nasal bones

Question 10

What is the nasal septum composed of?

Answer 10

Anterior portion= cartilage

Posterior portion= vomer

Question 11

What is the blood supply to the nasal cavity?

Answer 11

Internal carotid supplies superior portion
External carotid supplies inferior portion
Branches of these anastomose on the nasal septum to form the Kiesselbach plexus (Little area)

Question 12

Describe the innervation of the nasal cavity

Answer 12

Sensory innervation:

• Trigeminal nerve:
  
  • Va: superior
  • Vb: inferior
• Olfactory

Question 13

What can be a consequence of a fracture of the cribriform plate?

Answer 13

Loss of sense of smell due to shearing of projections of the olfactory nerve.

Leaking of CSF into the nasal cavity

Question 14

What are the 4 paranasal air sinuses?

Answer 14

Frontal
Ethmoid
Maxillary
Sphenoid

Question 15

Where does the frontal sinus drain into?

Answer 15

Drains inferiorly via frontonasal duct into the hiatus semilunaris

Question 16

Where is the hiatus semilunaris?

Answer 16

In the middle meatus

Question 17

Where do the sphenoid sinuses drain into?

Answer 17

Drain into the sphenoethmoidal recess

Question 18

Where do the ethmoid sinuses drain into?

Answer 18

Anterior: hiatus semilunaris
Middle: ethmoid bulla
Posterior: superior meatus

Question 19

Where do the maxillary sinuses drain into?

Answer 19

Superiorly into the hiatus semilunaris underneath the opening of the frontal sinus.

Question 20

What is the clinical relevance of the maxillary sinus drainage route?

Answer 20

Drains superiorly
Drainage route potential route for infection spread.
Superior drainage can lead to infection.
Inflamted mucosa can swell, further impeding drainage.

Question 21

What is the sensory innervation of the paranasal sinuses?

Answer 21

All innervated by Va of the trigeminal nerve

EXCEPT maxillary sinuses: Vb of the trigeminal.

Question 22

Where does the nasolacrimal duct drain into?

Answer 22

Inferior meatus

Question 23

Where can pain from maxillary sinusitis refer to?

Answer 23

Maxillary teeth

Question 24

What structure can be accessed surgically through the sphenoid sinus?

Answer 24

Pituitary gland

Question 25

What are the close anatomical relations of the ethmoid sinuses?
What is the clinical relevance of this?

Answer 25

Orbit
Infection spread from sinuses to orbit.
Plate of bone separating the two is thin and vulnerable to fracture.

Question 26

What can cause blockage of the nasolacrimal duct?

Answer 26

Nasal polyps
Trauma
Infection
Tumours

Question 27

What is a close anatomical relation of the sphenoid sinuses?

Answer 27

Cranial cavity