Hearing Anatomy W9 Flashcards
Auditory System
peripheral auditory, outer ear > middle ear > inner ear central auditory system, brainstem nuclei > auditory centers in the cortex
outer ear
pinna/auricle
localisation of sound
capturing sound energy
helix, tragus, lobule
external auditory meatus - aka external auditory canal, ear canal
funnels and resonates sounds
cartilage for 1st 1/3 then bone for 2/3
curved to protect the tympanic membrane
cerumen
cilia
Middle ear
air filled
encaswed by bone - temporal bone
tympanic membrane - ear drum, concave in shape, pressure conversion
ossicular chain - suspended in the middle ear cavity by ligaments
malleus (hammer) - attached to tympanic membrane
incus (anvil) - attaches to malleus
stapes (stirrup) - smallest bone in the body, attached to incus, footplate attached to oval window
amplifies
eustachian tube - middle ear
from middle ear to nasopharynx
sits closed at nasal entrance
inhibits foreign matter from entering the middle ear
prevents excessive ambient sound being transmitted to middle ear
opens due to yawning, swallowing, talking, chewing, levator veli palatini, tensor veli palatini
simultaneous soft palate elevation
ensures only nasally inhaled air equalises middle ear
inner ear
vestibular apparatus - aka semicircular canals
balance
auditory nerve - 30 000 fibres from cochlea
cochlea - hearing, 2.5 turns around modiolus
scala vestibuli - perilymph
scala media - endolymph
scala tympani - perilymph
modiolus - central axis
oval window - where the stapes articulates with the cochlea
round window - allows bulging of the cochlea fluid
inner hair cell vs outer hair cell
inner transmits sound info to brain 1 row
outer amplifies less sensitive sounds 3 rows
where is the auditory cortex?
heschl’s gyrus in temporal lobe
basilar vs apical ends of cochlea
basilar higher freq and apical lower freq
