Anatomy; Nasal Cavity and Paranasal Sinuses

Question 1

State the function of the nasal cavities

and describe how the anatomy/histology of the nasal cavities permits these functions

Answer 1

1. Acts as a patent conduit for air to be transported to the nasopharynx
2. Filters air of particulate material (vibrissae= small hairs)
3. Humidifies air (glands)
4. Warms inspired air in the nasal passage (blood)
5. Sense of smell as air passes over the olfactory epithelium

Question 2

Describe surface anatomy of the external nose

Answer 2

Question 3

Describe the anatomy of the nasal cartilages

Answer 3

Note the careful mix of bone and cartilage; we need some control and movement over our nose. It’s a passage into the body.

Question 4

Describe and identify the bony anatomy of the nasal cavities from a frontal external p.o.v.

Answer 4

Vomer is a tiny little triangular bone

Question 5

Which parts of the nasal cavity does the ethmoid bone form?

Answer 5

The ethmoid bone forms parts of the:

• roof
• lateral walls
• septum of the nasal cavity

Question 6

Show roughly where the ethmoid bone is

Answer 6

Question 7

Describe the ethmoid bone in detail

Answer 7

• I think the olfactory nerve goes from nasal cavity up through cribiform plate
• The vrest of crista galli gets some dura

Question 8

Draw the lateral wall of the right nasal cavity

Answer 8

• the concha increase in size from superior to inferior
• palatine makes up part of hard palate
• sphenoid sinus is where pituitary sits

Question 9

Draw the medial wall of right nasal cavity

Answer 9

Question 10

Explain how le fort fractures and basilar skull fracture can impact the nasal cavities

Answer 10

• le fort II & III fractures and basilar skull fracture can:
  
  1. disrupt the cribiform plate of the ethmoid
  2. anosmia (loss of smell)
  3. also, can disrupt the paranasal sinuses
  4. facilitate spread of infection

Question 11

List and describe the approximate locations of the 3 types of mucosa found in the nasal cavity

Answer 11

• Nasal Vestibule
  
  • stratified squamous epithelium (keratinsed to non-keratinsed)
• Nasal Cavity
  
  • respiratory epithelium
  • olfactory epithelium

Question 12

Where can the olfactory bulb and tract be seen on the brain?

(possible spot Q.)

Answer 12

Question 13

Describe how sense of smell works.

What household object can be used as a helpful metaphor?

Answer 13

CN I- Olfactory Nerves

• special sensory

Olfactory Pathway

1. Receptor cells in the olfactory epithelium
2. Pass up through the cribifrom plate
3. Synapse with olfactory bulb (ganglion)
4. Then neurons pass along olfactory tract
5. To temporal lobe and olfactory areas

A toothbrush!

Question 14

Describe the somatic sensory innervation

Answer 14

Question 15

Describe the areas of somatic sensory innervation and the associated nerves

Answer 15

Question 16

Summarise the arterial blood supply to the face

Answer 16

Question 17

Summarise/draw the arterial blood supply to the lateral and medial walls of the nasal cavities

Answer 17

Question 18

Discuss the relevance of Kiesselbach’s area

Answer 18

Kiesselbach’s area is:

• site where anastomosis occurs between the arterial contributions
• located anterioinferiorly on nasal septum

often leads to epitaxis (nose bleed)

Question 19

Describe the conchae and meatuses/recess of the lateral wall of the nasal cavities

Answer 19

3 conchae project from the lateral nasal wall creating four recesses/meatuses

a) sphenoethmoidal recess

1. superior nasal concha (ethmoid bone)

b) superior meatus

2. middle nasal concha (ethmoid bone)

c) middle meatus

3. inferior nasal concha (own bone)

d) inferior meatus

Conchae increase in size as you go down

Question 20

Indicate which structure or sinus(es) drain their contents into each meatus/recess

Answer 20

• a) Sphenoethmoidal recess*
• sphenoid sinus

1. Superior meatus

• posterior ethmoidal air cells

2. Middle meatus

• semilunar hiatus:
  
  • frontal sinus
  • maxillary sinus
  • anterior ethmoidal air cells
• ehtmoidal bulla
  
  • middle ethmoidal air cells

3. Inferior meatus

• nasolacrimal duct

Question 21

Describe the anatomy of inserting a nasogastric tube

Answer 21

Question 22

What do clinicians call conchae?

Answer 22

Turbinates

because they cause turbulent airflow through the nasal cavity

Question 23

What is a benefit of turbulent airflow through the nasal cavity?

Answer 23

Increases opportunity for humidifying, warming and filtering

Question 24

What does this MRI show?

Answer 24

It shows engorgement of the nasal mucosa

• this can impact air flow
• one side will be engorgede and then change to the other side every 1-5 hours
• due to erectile tissue (arteriovenous)

Question 25

List the bones that contain paranasal sinuses

Answer 25

Paranasal sinuses are found in: * frontal bone * ethmoid bone * maxilla * sphenoid

Question 26

Briefly discuss the anatomy of the paranasal sinuses

Answer 26

Paranasal sinuses are open spaces within bone The human body has four bilateral pairs associated with the nasal cavity: * frontal sinuses * ethmoidal air cells * maxillary sinuses * sphenoid sinuses Each sinus is lined with thin respiratory epithelium

Question 27

Summarise the anatomy of the lacrimal apparatus

Answer 27

Lacrimal fluid drains inferomedially to the nasolacrimal duct which drains to the inferior meatus

Question 28

What is sinusitis

Answer 28

Inflammation of the muscosa in 1/\> of the paranasal sinuses * acute/sub chronic/chronic

Question 29

How does sinusitis happen?

Answer 29

1. Cilia of the respiratory mucosa waft mucous towards ostia 2. Viral URTI can cause swelling of mucosa, reducing diameter of ostia 3. Sinuses can become filled with infected mucous

Question 30

Discuss the impact sinusitis could have on the local anatomy

Answer 30

When sinuses are filled with the infected mucous pressure builds INcreased pressure in ethmoid can break the medial wall of the orbit and impact the eye/spread infection to the optic nerve

Question 31

Discuss the relevant sensory innervation for sinusitis?

Answer 31

Sinusitis can be very painful - sensation is provided by CN V₁ and CN V₂ - AND may be referred to teeth

Question 32

Explain the potential clinical consequences of the relatively high location of the ostium of the maxillary sinus

Answer 32

The ostium of maxillary sinus is located superiorly in relation to its cavity * :. cilia must work against gravity * maxillary sinus is predisposed to infection

Question 33

What is an oroantral fistula

Answer 33

An oroantral fistula is abnormal communication between maxillary sinus and tooth socket