Ear

Question 1

Function of outer ear

Answer 1

Collects soundwaves and direct to middle ear

Question 2

Structures of outer ear

Answer 2

Helix, external acoustic canal (canal = meatus), auricle/ pinna, lobule/ earlobe

Question 3

What is the auricle/ pinna

Answer 3

composed of fibroelastic cartilage and covered in skin
Contains the lobule (composed of fibrous and adipose tissue) and helix

Question 4

what structures surround the external acoustic meatus

Answer 4

the first third has cartilage on either side, the rest will be surround by temporal bone

Question 5

what glands are in the external acoustic meatus

Answer 5

Ceruminous glands = secrete earwax

Question 6

Function of earwax

Answer 6

antimicrobial as it contains lysozyme and immunoglobins

traps foreign material

Question 7

Middle ear function

Answer 7

send sound vibrations to the oval window

Question 8

Structures in the middle ear

Answer 8

auditory ossicles
tympanic membrane
tympanic cavity
epitympanic recess

Question 9

What are auditory ossicles

Answer 9

malleus, incus and stapes
These transmit soundwaves to the oval window by vibrating

Amplify sound

Question 10

Structure of the tympanic membrane/ eardrum

Answer 10

three layer: outer layer of skin, middle layer of fibrous tissue and inner mucous membrane layer facing middle ear

Question 11

Function of the auditory tube/ eustachian tube

Answer 11

equalises pressure across the tympanic membrane
Links the middle ear with the nasopharynx allowing air to reach middle ear
*most of time it is closed - opens when movement of mandible and pharynx (swallowing and yawning)

Question 12

Function of the inner ear

Answer 12

Houses the receptors for hearing and balance

Question 13

Structures in the inner ear

Answer 13

cochlea
utricle
saccule

Question 14

labyrinths of the inner ear

Answer 14

bony labyrinth = cavities and channels of the temporal bone
membrane labyrinth = network of fluid filled membranes that fill bony labyrinth

Question 15

What is the vestibular apparatus

Answer 15

semicircular canals
Vestibule

Question 17

vestibule structure

Answer 17

in its lateral wall is the oval window
contains two otolithic organs = saccule and utricle

Question 18

Three components of the cochlea

Answer 18

scala vestibuli
scala media/ cochlear duct
scala tympani

Question 19

Physiology of hearing

Answer 19

tympanic membrane vibrates causing the malleus (connected to centre of eardrum) to vibrate
Vibration transmitted from malleus to incus then the stapes
stapes move back and forth

Question 20

How does the cochlea function

Answer 20

Scala vestibuli and tympani contain perilymph while scala media contain endolymph

Pushing of the stapes into the oval window causes the perilymph to vibrate
This causes endolymph to vibrate
As a result, basilar membrane vibrates
Cilia of the hair cells within the organ of corti will brush against tectorial membrane causing the hair cells to send impulses to the afferents of cochlear nerve

The nerve impulse generated is transmitted to brain

Question 21

pathway of the auditory signals

Answer 21

vestibulocochlear nerve terminates in the medulla oblongata
travels to midbrain, thalamus then temporal lobe

Question 22

Properties of sound waves

Answer 22

Pitch/ frequency
Location
Loudness/ amplitude

Question 23

How is the pitch detected

Answer 23

different frequencies stimulate the basilar membrane at different places along its length
near oval window = high frequency
near tip of cochlea = low frequency

Question 24

How is loudness detected

Answer 24

A high amplitude sound will cause greater stimulation of the auditory receptors in hair cells of spiral organ
There is greater force of scraping from the cilia across tectorial membrane

Question 25

What organs of ears are used in balance

Answer 25

semicircular canals = acceleration deceleration saccules = up and down, verticle position of head utricle = back and forward, lateral position of head otolithic organs = saccule and uticle

Question 26

physiology of detecting balance

Answer 26

a change in position of head causes movement of the endolymph bathing the cilia in semicircular canals and the otolithic membrane surrounding cilia in the saccule and utricle This stimulates the sensory receptors in the saccule and utricle and semicircular canal

Question 27

Cilia in otolithic organs

Answer 27

cilia moves left = increased rate of firing to vestibular nerve cilia moves right = decreased rate of firing to vestibular nerve

Question 27

Cilia of the ampullae

Answer 27

stereocilia and kinocilia Acceleration: stereocilia toward kinocilia Deceleration: kinocilia toward stereocilia

Question 28

What is ampullae

Answer 28

bulb structure at each end of the semicircular canal. Cntain cupulla filled with endolymph. Cristae is the layer of epithelial cells within the ampulla which will contain hair cells that have stereocilia and kinocilia attached to them

Question 29

direction of nerve impulse

Answer 29

vestibular nerve which connects to cochlear nerve to form vestibulocochlear nerve passing to cerebellum