Anatomy; Nasal Cavity and Paranasal Sinuses Flashcards
State the function of the nasal cavities
and describe how the anatomy/histology of the nasal cavities permits these functions
- Acts as a patent conduit for air to be transported to the nasopharynx
- Filters air of particulate material (vibrissae= small hairs)
- Humidifies air (glands)
- Warms inspired air in the nasal passage (blood)
- Sense of smell as air passes over the olfactory epithelium
Describe surface anatomy of the external nose
Describe the anatomy of the nasal cartilages
Note the careful mix of bone and cartilage; we need some control and movement over our nose. It’s a passage into the body.
Describe and identify the bony anatomy of the nasal cavities from a frontal external p.o.v.
Vomer is a tiny little triangular bone
Which parts of the nasal cavity does the ethmoid bone form?
The ethmoid bone forms parts of the:
- roof
- lateral walls
- septum of the nasal cavity
Show roughly where the ethmoid bone is
Describe the ethmoid bone in detail
- I think the olfactory nerve goes from nasal cavity up through cribiform plate
- The vrest of crista galli gets some dura
Draw the lateral wall of the right nasal cavity
- the concha increase in size from superior to inferior
- palatine makes up part of hard palate
- sphenoid sinus is where pituitary sits
Draw the medial wall of right nasal cavity
Explain how le fort fractures and basilar skull fracture can impact the nasal cavities
- le fort II & III fractures and basilar skull fracture can:
- disrupt the cribiform plate of the ethmoid
- anosmia (loss of smell)
- also, can disrupt the paranasal sinuses
- facilitate spread of infection
List and describe the approximate locations of the 3 types of mucosa found in the nasal cavity
- Nasal Vestibule
- stratified squamous epithelium (keratinsed to non-keratinsed)
- Nasal Cavity
- respiratory epithelium
- olfactory epithelium
Where can the olfactory bulb and tract be seen on the brain?
(possible spot Q.)
Describe how sense of smell works.
What household object can be used as a helpful metaphor?
CN I- Olfactory Nerves
- special sensory
Olfactory Pathway
- Receptor cells in the olfactory epithelium
- Pass up through the cribifrom plate
- Synapse with olfactory bulb (ganglion)
- Then neurons pass along olfactory tract
- To temporal lobe and olfactory areas
A toothbrush!
Describe the somatic sensory innervation
Describe the areas of somatic sensory innervation and the associated nerves
Summarise the arterial blood supply to the face
Summarise/draw the arterial blood supply to the lateral and medial walls of the nasal cavities
Discuss the relevance of Kiesselbach’s area
Kiesselbach’s area is:
- site where anastomosis occurs between the arterial contributions
- located anterioinferiorly on nasal septum
often leads to epitaxis (nose bleed)
Describe the conchae and meatuses/recess of the lateral wall of the nasal cavities
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
Indicate which structure or sinus(es) drain their contents into each meatus/recess
- 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
Describe the anatomy of inserting a nasogastric tube
What do clinicians call conchae?
Turbinates
because they cause turbulent airflow through the nasal cavity
What is a benefit of turbulent airflow through the nasal cavity?
Increases opportunity for humidifying, warming and filtering
What does this MRI show?
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)
List the bones that contain paranasal sinuses
Paranasal sinuses are found in:
- frontal bone
- ethmoid bone
- maxilla
- sphenoid
Briefly discuss the anatomy of the paranasal sinuses
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
Summarise the anatomy of the lacrimal apparatus
Lacrimal fluid drains inferomedially to the nasolacrimal duct which drains to the inferior meatus
What is sinusitis
Inflammation of the muscosa in 1/> of the paranasal sinuses
- acute/sub chronic/chronic
How does sinusitis happen?
- Cilia of the respiratory mucosa waft mucous towards ostia
- Viral URTI can cause swelling of mucosa, reducing diameter of ostia
- Sinuses can become filled with infected mucous
Discuss the impact sinusitis could have on the local anatomy
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
Discuss the relevant sensory innervation for sinusitis?
Sinusitis can be very painful
- sensation is provided by CN V1 and CN V2
- AND may be referred to teeth
Explain the potential clinical consequences of the relatively high location of the ostium of the maxillary sinus
The ostium of maxillary sinus is located superiorly in relation to its cavity
- :. cilia must work against gravity
- maxillary sinus is predisposed to infection
What is an oroantral fistula
An oroantral fistula is abnormal communication between maxillary sinus and tooth socket
