Auditory Tube Flashcards
What are the components of the auditory system?
Outer ear -air
Middle ear - air
Inner ear - fluid
Central Auditory Pathways
What are the different parts of the outer ear?
Channel the sounds in towards the auditory meatus (helical folds)
What are the smallest bones in the body?
the oscicles
Formed adult size at birth
Ear drum is in 2 parts
floppy one much more vulnerable
What is in the middle ear?
What is the attic?
In the middle ear
Which nerve travels across the back of the eardrum?
Facial nerve
Really risky in surgery
What is the role of the middle ear?
How does the mechanical energy (sound) get converted to electrical energy?
What do muscles do in the middle ear?
Protect the inner ear from acoustic trauma
Stapedius is stimulated acoustically so relies on reflex arc so can’t protect against rly quick sounds
What are the muscles in the middle ear?
tensor tympani - stabilises tympanic membrane
stapedius - stabilises stades
Where is the vestibulocochlear apparatus?
the inner ear
What is in the vestibulocochlear apparatus?
cochlear
labyrinth
innervation
3 sections of the cochlear?
What are the cochlear fluids?
2 ionic fluids
Endolymph (scala media)
high K+
Perilymph (scala vestibuli/ typani)
Like ECF and CSF
Na+ rich
Why are you likely to have impacted hearing with ion channel abnormalities?
ionic fluids in the cochlear
Oval window
window to scala vestibuli
What does the helicotremaa do?
allows wave movement in the cochlear, as it keeps the system open (it is a small hole at the end of the cochlea)
pressure moves through - moves the basilar membrane, it separaes the scala tympani and the scala media
How does movement of the basilar membrane cause sound?
stiff and narro - responds best to high frequency sounds w at base
broad and floppy at apex - responds best to low frequency sounds
different parts of the membrane move in response to different pitch - middle part is middle pitch, start is high pitch
Where is the organ of corti?
basilar membrane
inner hair cells attach tectorial to
difference between basilar and tectorial membrane?
tectorial is fixed
basilar membrane on histological level
inner hair cells move as basilar membrane is displaced, base is attached
inner hair cells moving causes activation of the auditory nerve - this activates the central auditory pathway
how do outer hair cells fine tune sound?
selectively activate the inner hair cells
How do movement of the sterocillia depolarise?
What is the pathway from the neurone to the brain?
What is sound localisation?
time difference of sound arriving
intensity difference - one side is quieter
so hearing in one ear - lose sound localisation and differentiation - overlap of sounds e.g. in cafe are hard
how does sound localisation work in the brainstem?
crossing over point - they don’t meet in the middle, one has
