chapter 15

Question 1

3 parts of the ear

Answer 1

• external
• middle
• inner

Question 2

external ear

Answer 2

• auricle/pinna

- shape serves to funnel sound waves into external auditory canal which terminates at the TM

Question 3

external auditory canal lined with glands that secrete

Answer 3

cerumen, a yellow, waxy material that lubricates and protects the ear.
-wax forms sticky barrier that helps keep foreign bodies from entering and reaching the TM

Question 4

how does cerumen exit the meatus

Answer 4

movements of chewing and talking

Question 5

TM characteristics

Answer 5

• translucent with pearly gray color
• prominent cone of line in the anteroinferior quadrant
• drum is oval and slightly concave pulled at the center by malleus

Question 6

parts of malleus

Answer 6

umbo, manubrium, short process

Question 7

small slack superior section of the TM

Answer 7

pars flaccida

Question 8

remainder of the drum (thicker and more taut)

Answer 8

pars tensa

Question 9

outer fibrous rim of the drum

Answer 9

annulus

Question 10

where lymphatic drainage of the external ear flows

Answer 10

parotid, mastoid, and superficial cervical nodes

Question 11

middle ear auditory ossicles

Answer 11

malleus, incus, stapes

Question 12

eustachian tube

Answer 12

connects middle ear with the nasopharynx and allows passage of air
-normally closed but opens with swallowing/yawning

Question 13

middle ear functions (3)

Answer 13

1. conducts sound vibrations from outer eat to the central hearing apparatus in the inner ear
2. protects the inner ear by reducing amplitude of loud sounds
3. eustachian tube allows equalization of air pressure on each side of the TM to prevent rupture

Question 14

inner ear embedded in

Answer 14

bone

Question 15

inner ear contains

Answer 15

bony labyrinth which holds the sensory organs for equilibrium and hearing

Question 16

vestibule and semicircular canals compose the

Answer 16

vestibular apparatus

Question 17

cochlea

Answer 17

snail shaped

central hearing appartus

Question 18

can the inner ear be accessible to direct examination

Answer 18

no but can assess functions

Question 19

function of hearing involves auditory system at 3 levels

Answer 19

1. peripheral
2. brainstem
3. cerebral cortex

Question 20

peripheral level

Answer 20

ear transmits sound and converts its vibrations into electrical impulses

Question 21

amplitude

Answer 21

how loud

Question 22

frequency

Answer 22

pitch

Question 23

how sound travels

Answer 23

• sound waves produce vibrations on TM
• vibrations carried out by middle ear ossicles to oval window
• sound waves travel through cochlea and dissipated against round window
• basilar membrane vibrates at specific point to the frequency
• hair cells of organ of corti bend and mediate vibrations into electric impulses
• electrical impulses conducted by CN VIII to the brainstem
• CN VIII from each ear sends signals to both sides of brainstem
• cortex interprets meaning of the sound and begin the appropriate response

Question 24

sensory organ of hearing

Answer 24

organ of corti

Question 25

brainstem level

Answer 25

binaural interaction permits locating the direction of a sound in space and identifying the sound - CN VIII from each ear sends signals to both sides of the brainstem - -brainstem sensitive to differences in intensity and timing of the messages from the two ears depending on the way the head is turned

Question 26

cortex

Answer 26

interprets the meaning of sound and begin the appropriate response

Question 27

normal pathway of hearing

Answer 27

air conduction | most efficient

Question 28

bone conduction

Answer 28

bones of the skull vibrate | -vibrations transmitted directly to the inner ear and to CN VIII

Question 29

hearing loss

Answer 29

anything that obstructs the transmission of sound impairs hearing

Question 30

conductive hearing loss

Answer 30

mechanical dysfunction of the external or middle ear - partial loss because person is able to hear if sound amplitude is increased enough - may be caused b y impacted cerumen, foreign bodies, perforated TM, pus or serum in the middle ear, and otosclerosis

Question 31

sensorineural loss

Answer 31

pathology of the inner ear, CN VIII, or auditory areas of the cerebral cortex -may be caused by presbycusis or ototoxic drugs

Question 32

presbycusis

Answer 32

gradual nerve degeneration that occurs with aging

Question 33

mixed loss

Answer 33

combo of conductive and sensorineural

Question 34

equilibrium

Answer 34

3 semicircular canals/labryinth in inner ear feed info to brain about the position of body in space -if labyrinth becomes inflames, feeds the wrong info to the brain creating a staggering gait and strong spinning/whirling sensation (vertigo)

Question 35

infant's eustachian tube

Answer 35

shorter and wider, more horizontal - easier for pathogens to enter nasopharynx to migrate through to the middle ear - lumen easily occluded - greater risk for ear infections

Question 36

otosclerosis

Answer 36

gradual bone formation that causes the footplate of the stapes to become fixed in the oval window, impeding the transmission of sound and causing progressive deafness

Question 37

aging adult's cilia

Answer 37

become coarse and stiff - cause cerumen to accumulate and oxidize - cerumen itself is drier because of atrophy of apocrine glands

Question 38

aging adult's hearing

Answer 38

presbycusis is a gradual sensorineural loss | -first notice high-frequency tone loss; harder to hear consonants than vowels

Question 39

otitis media

Answer 39

aka middle ear infection - occurs because of obstruction of the eustsachian tube or passage of nasopharyngeal secretions into middle ear - -creates ripe environment for bacteria to grow

Question 40

risk factors predispose to acute OM

Answer 40

- absence of breastfeeding in the first 3 months - exposure to SHS - daycare attendance - male sex - seasonality - bottle feeding in the supine position

Question 41

genetic variation of cerumen

Answer 41

either dry or wet

Question 42

dry cerumen

Answer 42

gray and flaky

Question 43

wet cerumen

Answer 43

honey brwon to dark brown and moist

Question 44

chromosome responsible for determining wet or dry cerumen phenotype

Answer 44

chromosome 16