Inner Ear

Question 1

what are the two main functions of the inner ear?

Answer 1

• convert mechanical signals from the middle ear into electrical signals
• maintain balance by detecting position and motion

Question 2

where is the middle ear located?

Answer 2

petrous part of the temporal bone

Question 3

what are the two main components of the middle ear?

Answer 3

• bony labryinth
• membranous labyrinth

Question 4

where do the bony labyrinth and the membranous layrinth of the inner ear lie?

Answer 4

bony - petrous part of temporal bone
membranous - within bony

Question 5

the structures of the bony labyrinth of the inner ear are lined internally with what? what fluid do they contain?

Answer 5

lined with periosteum
contain a fluid called perilymph

Question 6

what fluid is the membranous labyrinth of the inner ear lined with?

Answer 6

endolymph

Question 7

the inner ear has two openings into the middle ear - what are these?

Answer 7

oval window - between middle ear and vestibule
round window - between middle ear and scala tympani

Question 8

the bony labyrinth consists of what three parts?

Answer 8

cochlea
vestibule
semi-circular canasl

Question 9

the cochlea, vestibule and semi-circular canals are all part of what ear structure?

Answer 9

the bony labyrinth of the inner ear

Question 10

the vestibule is separated from the middle ear by what?

Answer 10

oval window

Question 10

what parts of the membranous labyrinth are located within the vestibule?

Answer 10

saccule and utricle

Question 11

what part of the membranous labyrinth is located within the cochlea?

Answer 11

cochlea duct - auditory part of inner ear

Question 12

the cochlea twists around a central portion of bone, forming a seashell shape - what is this bone called?

Answer 12

modiolus

Question 13

what bone extends out from the modiolus and ataches to the cochlear duct?

Answer 13

spiral lamina

Question 14

what chamber lies superiorly to the cochlear duct?

Answer 14

scala vestibuli

Question 15

what chamber lies inferiorly to the cochlear duct?

Answer 15

scala tympani

Question 16

the scala vestibuli and scala tympani are two chambers above and below the cochlear duct - what are they each filled with?

Answer 16

perilymph

Question 17

how many semi-circular canals are there in the bony labyrinth?

Answer 17

3 - anterior, lateral, posterior

Question 18

the semi-circular canals contain what? what are these important for?

Answer 18

contain semi-circular ducts, which are responsible for balance (alongside the utricle and saccule)

Question 19

the membranous labyrinth is a continuous system filled with what?

Answer 19

endolymph

Question 20

what 4 things is the membranous labyrinth composed of?

Answer 20

cochlear duct, 3 semi-circular ducts, saccule, utricle

Question 21

which of the following are organs of hearing, and which are organs of balance?
* semi-circular ducts
* cochlear duct
* saccule
* utricle

Answer 21

• semi-circular ducts - balance
• cochlear duct - hearing
• saccule - balance
• utricle - balance

Question 22

what are the following walls of the cochlear duct called?
* lateral wall?
* roof?
* floor?

Answer 22

• lateral wall - spiral ligament
• roof - Reissner’s membrane
• floor - basilar membrane

Question 23

what does the basilar membrane of the cochlear duct hold?

Answer 23

the Organ of Corti - epithelial cells of hearing

Question 24

which is larger - saccule or utricle?

Answer 24

utricle

Question 25

how does endolymph drain in the membranous labyrinth of the inner ear?

Answer 25

* drains from saccule and utricle into endolymphatic duct * duct travels through vestibular aqueduce to posterior aspect of petrous part of temporal bone * duct expands to a sac - endolymph is secreted and absorbed

Question 26

how do the semi-circular ducts help balance?

Answer 26

* head moves * endolymph within ducts changes speed and/or direction * sensory receptors in ampullae of canals detect this change * sends signals to brain about processing balance

Question 27

the bony labyrinth receives blood supply from what arteries?

Answer 27

* anterior tympanic branch * petrosal branch * stylomastoid branch

Question 28

the membranous labyrinth is supplied by what artery?

Answer 28

labyrinthine artery

Question 29

the labyrinthine artery divides into what 3 branches?

Answer 29

cochlear branch vestibular branches x2

Question 31

how does venous drainage of the inner ear occur?

Answer 31

labyrinthine vein

Question 32

what innervates the inner ear?

Answer 32

vestibulocochlear nerve (CN VIII)

Question 33

CN VIII (vestibulocochlear nerve) divides into what?

Answer 33

vestibular nerve - balance cochlear nerve - hearing

Question 34

Label the parts of the ear

Answer 34

Question 35

Label the membranous labyrinth

Answer 35

Question 36

Label the cochlear

Answer 36

Question 37

label the bony labyrinth

Answer 37