Ear Flashcards
parts of the ear
external, middle and internal
middle ear components
malleus, incus, stapes
internal ear components
cochlea and semicircular canals
what nerves can be found inn the external ear
CN’s 5,7,9,10
purpose of the auricle
funnels sound into the ear from surroundings but also reduces input from the posterior aspect
external ear/ear wax function
composed mostly of soft tissue= allows hair and ear wax to form
ear wax works as a protective barrier to increase water resistance in the ear, anti-bug, and works to remove dead skin from the interior as well
what seperates the external ear from the middle ear
tympanic membrane
the eustachian tube connects to which part of the ear?
middle ear
which ear structure is used for hearing
cochlea
which strucutre is used for balance
semicircular canals
function of the middle ear, how sound effects it?
sound moves into the ear as sound waves that push on the tympanic membrane that then presses on the malleus which presses on the incus and eventually the stapes which presses on the oval window. pressure on the oval window causes a fluid distortion that is converted to nn activity
how is the sound amplified
tympanic membrane is larger that the oval window which results in sound amplification
malleus, incus and stapes also form a lever action which helps to amplify hearing as well.
skin of the internal aspect of the external ear, implication?
directly on bone without underlying tisse=very weak
can be ruptured which leads to bacterial infection (lots of bacteria in the ear)
portions of the tympanic membrane, significance?
Pars tensa: 3 layers, rigid
pars flacida; 2 layer, less stiff
With ET dysfunction- pressure can cause the pars flacida to be pulled in as its less stiff
what nn passes thru the middle ear
chorda tympani
temporary tubes for ear infections
done in cases of chronic infection or ET dysfunction
slice the typmanic membrane and place a tube that allows the mid ear to connect with the outside world
can also allow the direct administering of drops of antibiotics for severe ear infections
fluids of the internal ear
endolymph- within the labyrinth, similar to ICF
perilymph- outside the labyrinth, similar to ECF
fracture of the temporal bone effects on the fluids of the internal ear
can lead to their mixture is severe which can result in a loss of hearing/ balance
semicircular canals
responsible for the detection of our position in 3 planes
Due to the 3 canals being positioned in 3 different planes
hearing mechanism at the cochlea
basement membrane is moved with distortion due to perilymph movement
which causes hair cells to be moved into the tectorial membrane resulting in neuronal stimulation of the cochlear nerve (in direction towards kinocilia)
hair cells responsible for hearing, others?
95% hearing from inner hair cells
outer hair cells may contribute to fine-tuning of hearing
utricle and saccule significance
both possess muculae-hair cells capable of detecting changes to acceleration and gravity
vestibular ganglion
portion of the vestibulocochlear nn that receives information from the maculae and semicircular canals
oreinatation of the head mechanism
tilting of the head will move the gelatinous layer above the hair cells and cause their distortion which stimulates them
leads to perception of head position
how we can percieve dif sound frequencies
high and low frequency sounds move variable distance into the cochlear tubing, high freq is short distance and long is further, this will activate dif hair cells to perceive the different stimuli
round window
acts as a vent to allow waves out of the internal ear and back to the middle ear which prevents echo
organ of corti
where mechanical info is translated into neurological info
possess the inner and outer hair cells
hair cells with streocilla- deformation towards the kinocilia (larger ones) results in depolarization, whereas deformation away from these cause inhibition
loud sounds effects on hair cells
damaging, can be temporary or permanent
cochlear implants
microphone projects sound to external coil which project signal to internal coil that then projects wire to the active electrode of the cochlea to send electrical signals to the cochlear nn
