anatomy of ear Flashcards
what is the medical term for outer ear
pinna / auricle
what is the external acoustic meatus
ear canal
what are the 2 structures that make up the outer ear
pinna
external acoustic meatus
where does the outer ear end
ear drum
where is the middle ear found
in the tympanic cavity
what 3 auditory ossicles/bones are found in the middle ear/ tympanic cavity
- malleus
- incus
- staples
what is the purpose of the malleus, incus and staples
transmit sound vibrations through the middle ear.
what is the middle ear usually filled with
air
what is the purpose of the middle ear/ what happens in the middle ear
- compression waves (sound waves) in the air cause tympanic membrane (ear drum) to vibrate
- movement is amplified and transmitted by the ossicles to the oval window where these vibrations are converted again into waves in the perilymph fluid of the inner ear
reflex contraction of the muscles in the middle ear can do what 2 things
- uncouple ossicles
- dampen sound sounds
what is the amplification factor of effective pressure in the middle ear and why is it this value
- x17
- the area of the oval window is about 17 times smaller than the tympanic membrane, with further amplification cause by lever action of malleus and incus
what muscle found in the middle ear is connected to the malleus
tensor tympani
how does the tensor tympani work to cause a dampening movement in response to loud noise
tensory tympani pulls the manubrium of the malleus medially, tensing the tympanic membrane (ear drum) and dampening movement in response to loud noise
(tympanic reflex)
where is the tensor tympani found
a muscle within the middle ear, located in the bony canal above the bony part of the auditory tube,
what is the stapedius muscle and its role
- connects to the staples
- dampness movement of stapes at the oval window
- a small muscle located inside the middle ear. It helps stabilize the stapes bone and is involved in regulating sound and protecting your inner ear from damage due to loud sounds
paralysis of the stapedius muscle with bell palsy (partial paralysis of facial muscles) can cause what pathology
hyperacusis
(reduced tolerance to sound)
what innervates the tensor tympani
mandibular division of trigeminal nerve
what innervates the stapedius
branch of facial nerve
both tensor tympani and stapedius are activated immediately prior to speaking and dampen snout to cochlea from the larynx