Chapter 9: Anatomy of Hearing Flashcards
pinna
-auricle
-yellow cartilage
-funnel sound
-passive ability to do sound localization
Landmarks: helix, tragus, concha cava, lobule
external auditory meatus
-located in what bone?
-where does it terminate? (what structure)
-it is lined with what?
-external ear canal
-osseous portion housed in temporal bone
-terminates at tympanic membrane or eardrum
-it’s a tube so it’s a resonance cavity
-outer portion is lined with fine hair and cerumen (earwax)
tympanic membrane
-separates which structures?
-what are its landmarks?
-eardrum
-separates outer ear from middle ear
-made of 3 sheets of layers: outer is continuation of epithelial of EAM, middle is more fibrous, inner is mucosal
Landmarks:
manubrium, umbo (point of attachment for malleus), cone of light - reflects light
-responsible for impedence-matching
outer ear pathologies
-otitis externa (swimmer’s ear) - inflammation of the outer ear
-auricular hematoma (cauliflower ear)
-cerumen impaction
middle ear
-what bones consist the ossicular chain?
-contains 3 smallest bones in the body (ossicles forming the ossicular chain)
-malleus
-incus
-stapes
what is the function of ossicular chain?
together, the malleus-incus-stapes transmit the acoustic energy from the tympanic membrane to the cochlea
-transmits vibration from eardrum to oval window
malleus
-largest ossicle
-manubrium provides point of attachment w tympanic membrane
-bulk of bone is head
incus
-provides intermediate link of ossicular chain
-articular surface - malleus
-lenticular surface - stapes
stapes
-smallest of the three
-footplate presses against oval window
tympanic muscles
-stapedius muscle - CN VII - neck of stapes
-tensor tympani - CN V - attached to manubrium
plays a role in stiffening the ossicular chain (dampen sounds)
eustachian tube
- keeps the ear dry
- maintain equilibrium between pressure
middle ear pathologies
- otitis (inflammation) media
- acute (recent) chronic (long time) serous (fluid)
-cholesteatoma - buildup of keratin
inner ear
- cochlea = hearing
- vestibular system = sense of balance
osseous cochlear labyrinth
-what bone is the cochlea embedded in?
-what window is the beginning of when sounds enter into the cochlea?
-embedded inside petrous portion of temporal bone
-oval window is the beginning of when sounds enter into the cochlea
-vibration pushes fluid and bulges the round window
-modiolus - core
what do you call the bulge of the middle ear?
cochlear promontory
what do you call the fluid in the cochlea on the other side of the oval window?
perilymph
where does the perilymph end up?
round window?
cochlear anatomy
-it is divided into what 3 structures?
-which structures contain perilymph?
-which structure contain endolymph?
-what other term do you call the scala media?
-what is the scala vestibuli and scala tympani divided by?
divided by 3 = scala vetibuli, scala tympani (perilymph), scala media or cochlear duct (endolymph)
media and tympani are separated by basilar membrane
cochlear duct (landmarks)
- scala media
-houses the organ of corti
-reissner’s membrane (roof)
-basilar membrane (floor)
organ of corti
-where does hearing take place?
-how many rows of hair cells does it have?
-how many are outer? inner?
-what structure separates the inner and outer hair cells?
-what do you call the cillia sticking out of the hair cells?
-what do you call the membrane on top of the organ of corti?
-where hearing actually takes place in terms of converting mechanical vibrations into electrical signals
-consists of 3 rows of outer hair cells, 1 row of inner hair cell (separated by tunnel of corti), has stereocilia
-above the organ of corti is the tectorial membrane
innervation of organ of corti
-what do you call the nerves that go TO and FROM the brain?
-afferent (to brain) - inner
-efferent (from brain) - outer = why? to do readjustments to the frequency
basilar membrane
-where is it stiff? base or apex?
-where is the high frequency? where is it low frequency?
base - stiff - so high frequency
apex - floppier - low frequency
spiral ganglia
-where do the cell bodies go?
nerve fibers thingy go here
conductive hearing loss
- when there’s a problem in any of the structures
sensorineural hearing loss
-problem with cochlea
vestibular system
-what kind of motion does it detect?
- to detect ROTATIONAL and LINEAR acceleration of the head/neck
- integrates sensory information
- eliminates movement artifacts
what are the 3 structures of the vestibular system?
semicircular ducts, vestibule (saccule and utricle), vestibular nuceli
what are the 3 semicircular ducts?
-whats their purpose?
-what is at the end of each duct? what fluid is it filled with?
-for detecting ROTATION
- anterior/superior (nodding yes or no)
- posterior (tilting head to the side)
- lateral/horizontal (left or right head movement)
have enlarged ends called ampullae filled with endolymph - has crista or cupula (gelatinous that can bend and there are hair cells sticking up to it)
ampulla
-what is it made of?
-made of gelatinous thingy that can flex (cupula)
-there are hair cells
vestibular sacs
-what are the 2 sacs called? what is their purpose?
-where are they located?
-utricle and saccule
-for detecting LINEAR acceleration
-located within the ampullae
-deflection of hair cells sends signal
function of outer ear
protect ear canal and middle ear
what is CN VIII
vestibulocochlear
