Auditory pathway Flashcards
What is found in the petrous part of the temporal bone? (2)
- cochlear
2. internal acoustic meatus
What type of energy does the external ear transmit?
sound waves
What type of energy change occurs in the middle ear? (2)
Sound waves to mechanical
What type of energy change occurs in the inner ear? (2)
mechanical to electrical
What cranial nerves run through the internal acoustic meatus?
vesitbulocochlear nerve (CN VIII)
facial nerve (CN VII)
What is the petrous part of the temporal bone like?
very hard
What is the ear drum known as?
tympanic membrane
What does the auditory tube do?
Connects to nasopharynx
enables air passage to maintain equilibrium of pressure
- goes wrong in planes
Why is the middle ear a high risk space? (5)
- connected to nasopharynx - prone to infection
- connected to mastoid air cells - infection may spread to middle cranial fossa
- internal jugular vein lies inferior - thrombosis risk
- internal carotid artery lies anterior - link to pulsatile tinnitus
- traversed by chord tympani and facial canal - infection risk
What also increases infection risk especially concerning nerves?
holes which nerves pass through
What is the inner ear?
series of fluid filled cavities
In the inner ear, what are the names of the series of cavities the petrous part of the temporal bone have and what do they contain?
- vestibule
- SSC - superior semicircular canal
- cochlea
perilymph
Where does the cochlear duct run through and what type of lymph does it contain?
runs through the cochlea
contains endolymph
What is the cochlear duct?
a membranous sac (closed tube) contain endolymph
What is the ion conc like in endolymph?
low sodium
high potassium
Things you need to know in inner ear? (5)
- posterior semicircular canal and duct
- vestibule
- lateral semi-circular canal and duct
- anterior semicircular canal and duct
- cochlea
What type of lymph does the cochlea contain?
perilymph
What two chambers does the cochlear duct separate the cochlea into?
- scala vestibuli
2. scala tympani