Ear (stephens)

Question 1

3 divisions of the ear

Answer 1

external ear
middle ear
internal ear

Question 2

external ear structures and function

Answer 2

auricle (pinna) and external auditory meatus

-collect and conduct sound, and protect eardrum

Question 3

blood supply to the auricle

Answer 3

superficial temporal and posterior auricular artery

Question 4

sound conduction

Answer 4

sound vibrations are conveyed to the inner ear via vibrations of ossicles and fenestra vestibuli

• air conduction and fenestra cochlea
• bone conduction through petrous temporal bone

Question 5

hearing receptors in inner ear are protected from trauma by 3 mechanisms

Answer 5

1) sudden, loud sounds cause footplate of stapes to rock side to side rather than depress directly into fenestra vestibuli
2) continuous loud sound cause contraction of stapedius and tensor tympani muscles and attenuation of vibrations
3) cochlear pathway in CNS is capable of filtering, focusing and attenuating sound

Question 6

auricular hematoma

Answer 6

trauma to pinna may cause hemorrhaging in subcutaneous tissue
-if not evacuated and bandaged scar tissue may grossly deform auricle into cauliflower ear
(superficial temporal and posterior auricular arteries)

Question 7

external auditory meatus shape and length

Answer 7

2.5 cm, curves slightly anteriorly as it ends blindly at tympanic membrane

Question 8

how to examine external auditory meatus during otoscopic examine

Answer 8

pull upward, outward and backward on auricle

Question 9

tympanic membrane location and size

Answer 9

located at medial end of external auditory meatus

• 1 cm in diameter
• tilted forward, lateral and downward in canal

Question 10

3 layers of tympanic membrane

Answer 10

outer epidermis innervated by GSA fibers from trigeminal and vaugs nerves

middle fibrous layer forms pars tensa
-absence of this in antero-superior quadrant forms pars flaccida

inner mucous membrnae innervated by GVA fibers of IX near tympanic plexus

Question 11

where does the chorda tympani nerve course through in tympanic membrane

Answer 11

through anterior and posteior mallear folds

Question 12

what is superior-anterior to tympanic membrnae

Answer 12

auditory tube

Question 13

what is superior-posterior to the tympanic membrane

Answer 13

long process of incus, stapes, fenestra vestibuli

Question 14

what is inferio-posterior to tympanic membrane

-clinical sig

Answer 14

fenestra cochlea

-electronic ray for cochlear implants here

Question 15

what is inferio-anterior to tympanic membrane

Answer 15

carotid canal

Question 16

malleus articulates with ___ and what nerve crosses its neck

Answer 16

articulates with incus

-chorda tympani crosses its neck

Question 17

incus articulates with what

Answer 17

between malleus and stapes

• body articulates with malleus
• long crus articulates with head of stapes

Question 18

stapes articulation

Answer 18

head articulates with long crus of incus

-anterior and posgterior crura connect the head to footplate which articulates with fenestra vestibuli

Question 19

tensor tympani muscle location and insertion

Answer 19

located in semicanal above auditory tube

-tendon inserts on handle of malleus

Question 20

innervation of tensor tympani muscle and function

Answer 20

mandibular nerve V3

-tightens tympanic membrane and attenuates its vibrations

Question 21

stapedius muscle location and insertion

Answer 21

located in pyramid on posterior wall of middle ear cavity

-tendon inserts on neck of stapes

Question 22

innervation of stapedius muscle

and function

Answer 22

facial nerve

-pulls stapes out of oval window (protection)

Question 23

facial nerve pathway leaving brainstem

Answer 23

facial nerve travels laterally in the internal auditory meatus then enters facial canal

• geniculate ganglion located just above here at this is where the nerve turns shaprly posteriorly to form external genu
• after 1.0 cm the nerve courses downward and sends a branch to the stapedius muscle and exits the stylomastoid foramen

Question 24

internal auditory meatus

location cochlear, facial and vestibular nerve

Answer 24

facial nerve
cochlear nerve——————–vestibular nerve

Anterior posterior

Question 25

what are the receptors of the inner ear

Answer 25

- cochlear receptors for hearing - receptors in semicircular ducts: detect angular acceleration - receptors in sacculus and utricle: detect linear acceleration

Question 26

inner ear receptors are innervaed by what and what function

Answer 26

cochlear division of VIII: innervates organ of corti (auditory info) vestibular division innervates semicircular ducts (static and dynamic postion-sense info for equilibrium)

Question 27

what artery innervates inner ear, and arteriorsclerosis of it may cause what

Answer 27

labyrinthine artery, branch of AICA | -vertigo, nausea

Question 28

what does the osseous labyrinth consists of

Answer 28

semicircular canals, vestibule, cochlea

Question 29

osseous labyrinth encloses the ___ space filled with ___

Answer 29

perilymphatic space filled with perilymph

Question 30

3 pairs of semicircular canals

Answer 30

anterior and posterior are oriented at a 90 degree angle in vertical plane lateral canal tilted 30 degrees upward from horizontal plane

Question 31

vestibule houses what

Answer 31

utricle (elliptical cavity) | saccule (spherical cavity)

Question 32

cochlea bony core is called ____ and what nerve passes through

Answer 32

modiolus, cohclear nerve passes through

Question 33

what projects from the modiolus

Answer 33

spiral lamina, cochlear duct is attached to spiral lamina

Question 34

semicircular ducts are dilated at one end = ___ | which contains a receptor organ called what and what is this function

Answer 34

ampulla, crista ampullaris | -detects angular acceleration

Question 35

utricle and saccule are located where and connect to form what

Answer 35

in vestibule, form endolymphatic duct

Question 36

the utricle communicates with what and contains what receptor organ and fnct of this

Answer 36

all 5 semicirular ducts, contains macula utricle, detects linear accelaration

Question 37

the saccule receptor organ and fnct

Answer 37

macula saccule, detects low frequency vibrations

Question 38

cochlear duct

Answer 38

continues with saccule contains organ of corti (spiral organ) receptors for hearing

Question 39

tiny blood vessels in area of spiral ligament called ____ supply organ of corti

Answer 39

stria vascularis

Question 40

prolonged exposure to excessive amounts of noise and or music may lead to destruction of what

Answer 40

organ of corti