Histology - Auditory and Vestibular Systems Flashcards
The outer ear contains (2)
pinna (auricle)
external auditory meatus (canal)
what are the tree parts of the ear
external ear
middle ear
internal ear
another name for auricle is
pinna
Middle ear contents (5)
tympanic membrane malleus incus stapes Eustachian tube
inner ear contents (5)
oval window semicircular ducts cochelea vestibulochoclear N round window
function of the external ear
collect and conduct sound
skin of the outer 1/3 of the ear contains________ and ______ glands that produce what
humerous sebaceous and ceruminous glands
produce cerumen “ear wax”
The auricle is supplied by what arteries
superficial temporal
posterior auricular
Auricular hematoma
caused by trauma –>damages blood supply to auricle–>hematoma
if blood is not drained=> cauliflower ear and/ or risk of infection
middle ear function
transfer sound waves in air into flud waves in the inner ear via vibration of the ossicles
ossicle attached to the tympanic membrane
malleus
ossicle between the malleus and the stapes
incus
footplate of this ossicle articuates with the fenestra vesibuli
stapes
another name for the oval window
fenestra vestibuli
what does the tensor tympani m do
tenses the tympanic membrane to decrease sound produced by chewing
what nerve innervates tensor tympani m
V3 of the trigeminal nerve (mandibular)
what does the stapedius muscle do
pulls the stapes away from the fenestra vestibuli to protect excess movement of the stapes due to loud sound
inn of stapedius muscle
facial n
function of eustachian tube
equalize pressure, connects nasopharynx to ear. decreases pressure of inner ear.
function of the inner ear
take fulid waves and transmit them into signals sent via the vestibulocochlear nerve to the cortex for hearing and balance
two main parts of the inner ear
membranous labrynth
osseous labrynth
Membranous labrynth
ducts tubes sacs filled with endolymph
suspended in the osseous labrynth
fluid in the membranous labrynth
endolymph
Osseous labrynth
bony portion, forms several canals and cavities
surrounds the membranous labrynth
perilymph(?)
perilymph is found where
between the walls of the osseous and membranous labrynths
contents of the membranous labyrinth (4) involved in balance and hearing
semicircular ducts
utricle
saccule
cochlea
semicircular ducts
tubes suspended in the osseous semicircular canal
each semicircular duct ends in an
ampulla
each ampulla of the semicircular duct contains ______
a receptor organ = crista ampullaris
crista ampularis detects
angular acceleration
what structure is attached to the end of the semicircular ducts
utricile
receptor organ of the utricle
macula utricle
macula utricle detects
linear acceleration
What is conneced directly to the cochlear duct
saccule
the receptor organ of the saccule
macula saccule
macula saccule detects
linear accleratino
the components in the membranous labrynth specific to the vestibular system
semicircular ducts
utricle
saccule
components in the membranous labyrinth specific to hearing
cochlea
crista ampullaris detects
angular acceleration - rotation of the head
crista ampullaris - big picture
conains hair cells with sterocilia that detect the movement –> depolarization –> signal sent to brainstem via the vestibular nerve
crista ampullaris - how it works
when the head turns, endolymph in the semicircular ducts pushes against the CUPULA –> bends the stereocilia of the hair cells –> the bending stimulates afferent activity through CN8 to the brainstem
what is the cupula and its function
???
Macula utricle and macula saccule detect what
linear accleration (horizontal movement) linear acceleration (vertical movement)
macula utricle and macula saccule - big pictue
the utricle and saccule contain hair cells topped with otoliths (Ca carbonate crystals) that detect the movement –>depolarization –> signal sent to brainstem via vestibular nerve
macula utricle and macula saccule - how it works
the saccule and utricle lie 90degrees to each other –> head moves in any direction–> the sterocilia of the hair cells will bend due to the weight of the otoliths –> the bending stimulates afferent activity through CN8 to the brainstem
otoliths are
Ca carbonate crystals
endolymphatic duct is a duct formed by the joining of
ducts from the utricle and saccule
the endolymphatic duct ends in the ____ space
subdural
THe _______ drains the perilymph
perilymphatic duct
the perilymphatic duct extends through the ______ and ends in the ______ space. Why do we care
dura
subarachnoid
can be a possible cause of meningitis
most common cause of the symptoms of vertigo
benign paroxysmal positional vertigo
Benign paroxysmal positional vertigo is charachterised by
breif recurrent episodes of vertigo triggered by change in head position with respect to gravity
what is the cause of benign paroxysmal positional vertigo
debris floating in the endolymph of one or more of the semicircular canals
how do you diagnose bppv?
Dix-Halpike maneuver
Scala vestibuli aka
vestibular duct
scala vestibuli is located inside the _____, filled with ____ and extends from ______ to ______
cochlea
perilymph
oval window
the helicotrema
scala tympani aka
tympanic duct
scala tympan is located in side the _____, filled with _______ and extends from _____ to ________
cochlea
perilymph
helicotrema to round window
Vestibular membrane separates what
the vestibular duct from the cochlear duct
the basilar membrane separates what
the cochlear duct from the tympanic duct
The helicotrema is where? It is a connection point for what
at the apex of the cochlea
connection point for the vestibular and tympanic ducts
The cochlear duct is located____, filled with _____ and houses ____
inside the cochlea,
endolymph
organ of corti
The organ of corti contains _____. it is composed of _____
the cochlear nerve
hair cells
what is the purpose of the hair cells in the organ of corti
detect movement –> stimulate depolarization –> sends signal to brain via cochlear nerve–> sound
The purpose of the vestibular and tympanic ducts
to conduct sound vibrations in the air into fluid sound waves that are transmitted to the organ of corti inside the cochlear duct.
how we hear sound
- sound waves in air hit external ear
- they go to tympanic membrane, cause ossicles in middle ear to vibrate
- vibration of ossicles (stapes) transmits movement to oval window of inner ear
- stapes hitting oval window causes movement of fluid within the inner ear
- fluid waves move up and down from the oval window to the round window (via the vestibular and tympanic ducts)
- movement of the fluid waves causes bibration of the basilar membrand and hence the organ of corti inside the cochlear duct to move
- movement of the hair cells inside the organ of corti trigger depolarization
- depolarization allows signals to be sent to the brain via the cochlear nerve
- interpretation of sound
why is otitis external more common in children
their external auditory meatus is more horizontal
Otitis externa
pain with manipulation of ear
aka swimmers ear
otitis external infection caused by
pseuomonas aeruginosa or staph aureus
otitis media
infection caused by
bulging tympanic membrane, erythema, middle ear effusion
strep pneumoniae
haemophilus influenza
morexella catarrhalis
Meniere’s Disease and triad of Sx’s
excessive endolymphatic fluid within the inner ear
intermittant vertigo, tinnitus, and hearing loss
Vestibular neuritis
inflammation of vestibular nerve
spontaneously begins and spontaneously resolves - lasts about 2wks
nausea, vomitting, vertigo without hearing loss or tinnitus
tinnitus
?????
