The Nasal Cavity 2 Flashcards
what forms a portion of the roof of the nasal cavity?
The cribriform plate (part of the ethmoid bone) It forms a portion of the roof of the nasal cavity
what openings does the cribriform plate (ethmoid bone) contain? what travels through?
very small perforations, allowing fibres of the OLFACTORY (CN I - smell) nerve to enter and exit
where is the sphenopalatine foramen located?
At the level of the superior meatus
what is the function of the sphenopalatine foramen?
This hole allows communication between the nasal cavity and the pterygopalatine fossa
what passes through the sphenopalatine foramen?
The sphenopalatine artery,
nasopalatine and superior nasal nerves
what is the incisive canal?
a pathway between the nasal cavity and the incisive fossa of the oral cavity
what travels through the incisive canal?
nasopalatine nerve and greater palatine artery
how is the blood supply like in the nose? why?
very rich vascular supply – allows it to effectively change humidity and temperature of inspired air
where does the nose receive blood supply from?
both the internal and external carotid arteries
what are branches of the internal carotid artery which supplies the nose?
Anterior ethmoidal artery
Posterior ethmoidal artery
what are the ethmoidal arteries branches of?
the opthalmic artery
how do the ethmoidal arteries travel through the skull?
They descend into the nasal cavity through the cribriform plate
what are the branches of the external carotid artery which supply the nose?
Sphenopalatine artery
Greater palatine artery
Superior labial artery
Lateral nasal arteries
In addition to the rich blood supply, what happens to the arteries supplying the nose?
they anastamoses with each other
where is anastomoses of the arteries most prevalent?
in the anterior portion of the nose
where do the veins of the nose travel and drain to?
The veins of the nose tend to follow the arteries
drain into the pterygoid plexus, facial vein or cavernous sinus
what can nasal veins join with in some individuals? resulting in?
a few nasal veins join with the sagittal sinus (a dural venous sinus)
represents a potential pathway by which infection can spread from the nose into the cranial cavity
what is epistaxis?
nosebleed
where is epistaxis most common?
anterior 1/3rd of nasal cavity - Kisselbach’s area
causes of epistaxis?
local e.g. trauma
systemic e.g. hypertension
how can the innervation of the nose be divided?
into special and general innervation
what is special sensory innervation of the nose?
the ability of the nose to smell
carried out by the olfactory nerves (CN I)
what is the olfactory bulb and where is it found?
part of the brain, lies on the superior surface of the cribriform plate, above the nasal cavity
where do branches of the olfactory nerve (special sensation: smell) travel?
run through the cribriform plate (ethmoid bone)
where does general sensory innervation to the septum (middle) and lateral walls from?
the nasopalatine nerve and the nasociliary nerve
what are the nasociliary and nasopalatine nerves a branches of?
nasociliary = ophthalmic nerve (V1 - higher up) nasopalatine = maxillary nerve (V2)
what supplies innervation to the external skin of the nose?
the trigeminal nerve
causes of fracture of the cribriform plate?
can occur as a result of nose trauma
either fractured directly by the trauma, or by fragments of the ethmoid bone
what can a fractured cribriform plate result in?
A fractured cribriform plate can penetrate the meningeal linings of the brain, causing leakage of cerebro-spinal fluid
what happens if there is leakage of CSF?
Exposing the brain to the outside environment, increases risks of meningitis, encephalitis and brain abscesses
what else can be irreversibly damaged in a cribriform plate fracture?
The olfactory bulb lies on the cribriform plate and can be damaged irreversibly by the fracture
how will patients present if the olfactory bulb is damaged?
anosmia (loss of smell)
