ears Flashcards
ear
the sensory organ for hearing and maintaining equilibrium
auricle
the external ear
pinna
moveable cartilage and skin
the external ear ____
funnels sound into its opening– the external auditory canal
external audits canal
the canal is a cultural-de-sac 2.5 - 3.5 cm long in adults. has a slight S curve
The middle ear
a tiny air filled cavity inside the temporal bone containing the tiny auditory ossicles:
1. malleus
2. incus
3. stapes
conducts sound vibrations from outer ear to central hearing apparatus
protects inner ear by reducing amplitude of sounds
Eustachian tube allows equalization of air pressure on each side of the TM so that it does not rupture
the inner ear
contains the
- bony labyrinth
- vestibular apparatus
the bony labyrinth
holds the sensory organs for equilibrium and hearing
tympanic membrane
or eardrum separates the external and middle ear. It is translucent with a pearly gray color and a prominent cone of light in the anteroinferior quadrant ( which is the reflection of the otoscope light) pars flaccida pars tensa annulus
The parts of the malleus…….
show through the translucent drum- these are the jumbo, the manubrium, and the short process
Cerumen
determined genetically and comes in two major types
1. dry cerumen which is gray and flaky and frequently forms a thin mass in the ear canal
2. wet cerumen which is honey to dark brown and moist.
caucasian most
eustachian tube
opening that connects middle ear with nasopharynx and allows passage of air
normally closed but opens with swallowing or yawning
vestibular apparatus
vestibule and semi cultural canals within the bony labyrinth compose the vestibular apparatus
hearing
auditory system can be divided into three levels
- peripheral
- brainstem
- cerebral cortex
peripheral
ear transmit sounds and converts to electrical impulses which can be analyzed by the brain
amplitude-loudness
frequency- pitch or number of cycles per second
brainstem
locates direction of sound in space
cerebral cortex
interprets meaning of sounds
pathways of hearing
normal pathway of hearing air conduction: most efficient
alternate-bone conduction
the bones of the skull vibrate transmit to inner ear and cn VIII
hearing loss
anything obstructing transmission of sound
conductive hearing loss
involves a MECHANICAL dysfunction of external or middle ear
- impacted cerumen
- foreign bodies
- perforated tm
- purulent or serous fluid in middle ear
- otosclerosis-decrease in mobility of ossicles
sensorineural hearing loss
signifies pathology of inner ear, cranial nerve VIII or auditory areas of cerebral cortex.
presbycusis
gradual nerve degeneration that occurs with aging
ototoxic drugs
affects hair cells in the cochlea
mixed hearing loss
combination of conductive and sensorineural types in the same ear
equilibrium
the bony labyrinth in the inner ear feeds information to brain about the body’s position in space
determines
1. verticality and depth
2. registers angle of head in relation to gravity
3. if labyrinth becomes inflamed it feeds wrong information to the brain creating a staggering gait and a strong spinning, whirling sensation called vertigo
Infant and children
inner ear starts to develop in 5th week of gestation
infant eustachian tube
relatively shorter and wider and more horizontal than adults
easier for pathogens from nasopharynx to migrate to middle ear
increased risk for OM
otosclerosis
common cause of conductive hearing loss
age 20-40
gradual hardening that causes foot plate of stapes to become fixed in the oval window
impedes transmission of sound and causing progressive deafness
presbycusis
gradual sensorineural loss caused by nerve degeneration in inner ear and auditory nerve
onset usually occurs in 50s and slowly progresses
first notice high frequency tone loss
whisper test
occlude 1 ear
1-2 feet from ear and whisper two syllable words
tuning fork test
weber test
rinne test
tuning fork
to activate tuning fork hold is by the stem and strike tines softly on back of your hand
a hard strike makes tone too loud and it takes a long time to fade out
weber test
place vibrating tuning fork midline on top of person’s skull
can use forehead if unable to hear
normal sound heard equally in both ears
abnormal sound heard only on one side
rinne test
strike tuning fork place on mastoid until unable to hear then place tines in front of external auditory meatus be sure to time hearing normal AC> BC usually 2: 1
