nasal cavities and paranasal sinuses Flashcards
name 5 functions of the nasal cavities
acts as a patent conduit for air to be transported to the nasopharynx
filters air of particulate
humidifies air (glands)
warms air in the nasal passage (blood)
sense of smell as air passes over the olfactory epithelium
what filters air of particulate material?
vibrissae (small hairs)
what are the external components of the nose?
root dorsum tip ala nostril/nares septum philtrum (of upper lip)
the external nose is made of bone, true or false?
false
mixture of bone and cartilage
cartilage allows movement and change in shape of the nose
what bones form the nose?
nasal processes of frontal and maxilla bone nasal bone ethmoid bone - perpendicular plate of ethmoid bone vomer inferior nasal concha
what bones form the septum?
perpendicular plate of ethmoid
vomer
what are the components of the ethmoid bone?
perpendicular plate
cribiform plate = horizontal plate on top of perpendicular plate
crista galli = vertical plate sitting above cribiform plate
ethmoidal air cells
which conchae does the ethmoid bone form?
superior and middle conchae
which parts of the nose does the ethmoid form?
parts of the roof, lateral walls and septum of nasal cavity
how is the inferior concha different to the middle and superior?
inferior is its own bone
while middle and superior are part of the ethmoid
where do the conchae originate and extend into?
originate laterally and project medially towards the perpendicular plate of ethmoid (septum)
which types of le fort fractures can affect the cribiform plate of ethmoid?
le fort 2 and 3
what problem can result from disruption of cribiform plate?
anosmia (loss of smell)
name another potential problem with le fort fracture
disruption of paranasal sinuses which can facilitate spread of infection
what are the 2 areas of nasal mucosa?
nasal vestibule
nasal cavity
what type of epithelium lines the nasal vestibule?
stratified squamous epithelium (keratinised to non-keratinised)
what type of epithelium lines the nasal cavity?
respiratory epithelium olfactory epithelium (sits superiorly)
what is respiratory epithelium?
ciliated pseudostratified columnar epithelium with goblet cells
what nerve is involved in olfaction?
olfactory nerve (CN 1) special sensory
describe the 5 steps in the olfactory pathway
- receptor cells in the olfactory epitheliu
- pass up through the cribiform plate
- synapse with olfactory bulb (ganglion)
- then neurons pass along olfactory tract
- to temporal lobe and olfactory areas
describe olfactory epithelium
ciliated pseudostratified columnar
with villi?
describe somatic sensory innervation of the nasal cavity
upper portion = CN V1 (anterior ethmoidal nerve)
lower portion = CN V2 (nasopalatine nerve)
how does the nasopalatine nerve enter the nasal cavity?
via sphenopalatine foramen
branches into 2 in each cavity
1 branch supplies lateral wall
1 branch supplies septum
describe blood supply to the nose
originates from internal and external carotid - facial artery - maxillary artery - ophthalmic artery branches of all of the above
what is kiessalbach’s area?
AKA little’s area
site where anastomosis occurs between the arterial contributions
located anterioinferiorly on nasal septum
site of nosebleeds from trauma to nose etc
what arteries contribute to the kiesselbach’s area
anterior ethmoidal posterior ethmoidal sphenopalatine artery greater palatine artery lateral nasal artery septal branch of superior labial artery all branches of - facial artery - ophthalmic artery - maxillary artery
what spaces exist above and below the nasal concha?
above superior concha = sphenoethmoidal recess
below superior concha = superior meatus
below middle meatus = middle meatus
below inferior concha = inferior meatus
where is an NG tube inserted?
below inferior concha
describe what happens in the nasal cycle
airflow through the nose can be impacted by engorgement of the nasal mucosa
one side will be engorged then change to the other side every 1-5 hours
due to erectile tissue (arteriovenous)
what are paranasal sinuses and name the 4 bilateral pairs?
open spaces within the skull frontal sinuses ethmoidal air cells maxillary sinuses (sometimes referred to as the antrum) sphenoid sinuses
what lines the paranasal sinuses?
thin respiratory epithelium
where is the sphenoid sinus in relation to the nasal cavity?
at upper aspect of posterior wall
where does the sphenoid sinus drain?
sphenoethmoidal recess
where does the posterior ethmoidal air cells drain?
superior meatus
what sinuses drain into the semilunar hiatus of the middle meatus?
frontal sinus
maxillary sinus
anterior ethmoidal air cells
what drains into the ethmoidal bulla of the middle meatus?
middle ethmoidal air cells
what drains into the inferior meatus?
nasolacrimal duct
describe the route of drainage of lacrimal fluid
drains inferomedially to the nasolacrimal duct which drains into the inferior meatus
what is sinusitis and how does this occur?
inflammation of the mucosa in 1 or more of the paranasal sinuses
cilia of resp mucosa waft mucous towards ostia
viral URTI can cause swelling of mucosa, reducing diameter of ostia
sinuses can become filled with infectious mucous and pressure builds
name a potential complication of sinusitis
build up of fluid in the sinuses can cause increased pressure
increased pressure in ethmoid and break the medial wall of the orbit and impact the eye/spread the infection to the optic nerve
why is the maxillary sinus particularly predisposed to infection?
ostium of maxillary sinus is located superiorly in relation to its cavity
cilia must work against gravity
how can tooth extraction cause sinusitis?
oro-antral fistula can form between tooth socket and maxillary sinus allowing tooth infection to track up into the sinus if the roots pierce upwards into the maxillary sinus
or if improper closure of oro-antral fistula
