13-3: Ear Anatomy

Question 1

outer ear

Answer 1

designed to collect soundwaves and direct them inwards, consists of auricle/pinna, external acoustic meatus, and tympanic membrane

Question 2

auricle

Answer 2

flap of elastic cartilage shaped like a funnel, covered with skin and attached to the head by ligaments and muscles; collects sound waves and funnels them into the ear

Question 3

external acoustic meatus

Answer 3

one inch tube in the temporal bone, from the auricle to the eardrum. The skin lining this bony tube has hairs and ceruminous glands that secrete earwax

Question 4

What is the function of the external acoustic meatus?

Answer 4

keeps dirt, bugs and small objects out of ear and protects the ear drum.

Question 5

tympanic membrane

Answer 5

aka eardrum; thin connective tissue partition separates the outer and middle ear (appears shiny white); vibrates when soundwaves hit it, causing bones in middle ear to move

Question 6

middle ear

Answer 6

small air-filled cavity in the temporal bone. Separated from outer ear by tympanic membrane and from inner ear by a thin bony wall with two windows

Question 7

eustacian tube

Answer 7

connects the middle ear to the nasopharynx; infections often travel from the nose and throat to middle ear through this tube

Question 8

What is the function of the eustacian tube?

Answer 8

equalizes air pressure on both sides of eardrum, preventing it from rupturing - opens when swallowing or yawning

Question 9

ossicles

Answer 9

3 tiny bones extending across middle ear, named for shape

Question 10

literally “hammer”

Answer 10

malleus - attached to inner surface of eardrum

Question 11

literally “anvil”

Answer 11

incus - in the middle

Question 12

literally “stirrup”

Answer 12

stapes - fits into oval window in the bony wall between the middle and inner ear

Question 13

inner ear

Answer 13

aka labyrinth - consists of two parts: bony labrynth and membranous labyrinth

Question 14

bony labyrinth

Answer 14

series of cavities in the temporal bone, filled with perilymph. Consists of vestibule, cochlea, and semicircular canals

Question 15

vestibule

Answer 15

central, egg shaped cavity of inner ear, contains oval window

Question 16

cochlea

Answer 16

anterior to the vestibule, bony spiral resembles a snail shell

Question 17

semicircular canals

Answer 17

3 bony canals projecting up and back from the vestibule; at right angles to each other.

Question 18

ampulla

Answer 18

swelling at the end of each semicircular canal, has receptors for equilibrium and balance

Question 19

membranous labyrinth

Answer 19

interconnecting sacs and ducts inside bony labyrinth. Suspending in perilymph, but filled with endolymph

Question 20

utricle and saccule

Answer 20

sacs suspended within the vestibule

Question 21

semicircular ducts

Answer 21

line the canals, connect to the utricle

Question 22

What are the three channels within the cochlea?

Answer 22

scala vestibuli, scala tympani, cochlear duct

Question 23

The external and middle ear are filled with ___; the bony labyrinth with ___; the membranous labyrinth with ___.

Answer 23

air; perilymph; endolymph

Question 24

scala vestibuli

Answer 24

upper, bony channel, filled with perilymph. Connects with the oval window

Question 25

scala tympani

Answer 25

lower, bony channel, filled with perilymph; ends at the round window

Question 26

cochlear duct

Answer 26

membranous channel between the other 2, filled with endolymph

Question 27

The cochlear duct is separated from the scala vestibuli by the ___ and the scala tympani by the ___.

Answer 27

vestibular membrane; basilar membrane

Question 28

organ of corti

Answer 28

organ of hearing - located on the inner surface of the basilar membrane in the cochlear duct.

Question 29

stereocilia

Answer 29

auditory receptors lining organ of corti

Question 30

The free ends of the hair cells in the organ of ___ extend into the ___ of the cochlear duct, and are covered by ____.

Answer 30

corti; endolymph; tectorial membrane

Question 31

The base of hair cells connect to neurons of the cochlear branch of cranial nerve ___ (aka ____)

Answer 31

VIII; vestibulocochlear

Question 32

labyrinthitis

Answer 32

inflammation of inner ear