Ear Flashcards
Path of sound waves through ear
External auditory canal Tympanic membrane Malleus Incus Stapes Oval window Fluid of inner ear Fluid filled cochlea Sensory hair cells on membrane (organ of corti) of spinal organ
Tympanic membrane
fibrous membrane separating external auditory canal from middle ear
The ossicles: malleus, incus, stapes
transmit sound from tympanic membrane to oval window
The oval window
connects ossicles to scala vestibule-perilymph
Intersection of middle and inner ear
The round window
as stapes footplate moves into oval window, round window moves out
allows movement of fluid within the cochlea leading to movement of cochlea inner hair cells
the auditory tube (eustachian)
connects nasopharynx to middle ear - equalising pressure
external auditory canal
lined by skin that produces ear wax - viscous secretions from sebaceous glands, less viscous from apocrine, sheds layers of skin (keratin), fatty acids, alcohol, squalene, cholesterol.
traves
conveyer belt process of epithelial migration aided by jaw movements.
migrate from umbo to entrance of ear canal
what is the umbo?
centre of the tympanic membrane
function of the chorda tympani
taste to ant. 2/3 tongue
parasym to subman and subling
middle ear
filled with air
respiratory epithelium
liable to infection of URTI
connected antero-inferiorly to the nasopharynx
middle ear is connected posteriorly to
mastoid air cells
through aditus to mastoid antrum
where does internal jugular lie relative to middle ear?
inferior
where does IC art lie relative to middle ear?
ant.
pulsatile tinnitus
how do chorda tympani and facial canal lie relative to middle ear?
traverses it
path of chorda tympani and facial nerve
`through temporal bone via internal auditory tube and winds around middle ear bones
tensor tympani - nerve innervation and why
V3 trigeminal
contractions pulls handle of malleus medially
stapedius - nerve innervation and why
pull stapes posteriorly and prevents excessive vibrations
where is the inner ear?
within the petrous temporal bone filled with perilymph
within the cavity of the inner ear there is a sac?
epithelial sac, membraneous labyrinth, filled with fluid called endolymph
Receptors within membraneous labyrinth
Maculae - vestibular receptors
Christae ampullaris - vestibular receptors
Spiral organ (organ of corti) - auditory receptors
maculae location
utricle and saccule
balance - sensory info about static position of head in space
christae ampullaris location
semicircular ducts in ampulla
change of direction and rate of movement of head
structural similiarities between maculae and christae ampullaris
same morphological type
single layer of columnar cells cont. with simple cuboidal epithelium
hair cells have numerous stereocilia
nystagmus
rapid involuntary eye movements
vertigo
dizziness and abnormal perception of motion
organ of corti
specialised region of wall of cochlear duct
part of membraneous part within bony cochlea
the bony cochlea spirals around the
spiral ganglion made of cell bodies of 1st order auditory neurons
where does high frequency go
near oval window - base
where does low frequency go
helicotrema - apical end
first order sensory join what fibres to where
cochlear nerve to vestibulocochlear to internal acoustic meatus
conduction deafness
sounds cannot pass freely to inner ear
sensorineural deafness
damage to hair cells in cochlear - irreversible
