N18 auditory system

Question 1

define hearing

Answer 1

neural perception of sound energy

Question 2

Define sound

Answer 2

audible distrubance of molecules in a medium eg air or water

Question 3

describe sound waves

Answer 3

longitudinal waves
frequency - pitch
amplitude - volume

Question 4

what is the audible range?

Answer 4

20 hz - 20 kHz

Question 5

give a brief description of external ear and list its contents

Answer 5

external - Air - collection

• EAM
• auricle

Question 6

give a brief description of the middle ear and list its contents

Answer 6

Middle - bone - concentration 
oval window 
round window 
malleaus, incus and stapes
nasopharyngel tube

Question 7

give a brief description of inner ear and list its contents

Answer 7

cochlea

internal auditory meatus

Question 8

what type of joints are between the middle ear bones?

Answer 8

synovial

Question 9

how are vibrations created in the perilymph?

Answer 9

stapes rock back and forth on oval windows to create vibrations on perilymph

Question 10

inner ear - cochlea

how are vibrations reach oval window?

Answer 10

vibrations detected and travel through perilymph to round window

Question 11

how are vibrations transferred across the ear?

Answer 11

via the three ear bones
malleus
incus
stapes

Question 12

which labyrinth contains perilymph?

Answer 12

bony

Question 13

which labyrinth contains endolymph?

Answer 13

membranous

Question 14

structure of the cochlea

Answer 14

3 tubes running through ;
scala tympani
scala media
scala vestibule

helicotrema is the tip

organ of Corti is within the scala media

Question 15

what does the tectorial membrane have resting on it?

Answer 15

inner and outer hair cells

Question 16

what is the function of outer and inner hair cells?

Answer 16

outer - vibration of hair cells increase to increase movement
inner - you can only hear with inner hair cells

Question 17

what is the function of the Organ of Corti?

Answer 17

detects soundwaves produced in the fluid in the cochlea by vibration of the stapes and sends action potentials centrally in the cochlear division of the vestibulocochlear

Question 18

what are the sensory cells?

Answer 18

hair cells

Question 19

which fluid is present in the scala media and duct?

Answer 19

endolymph

Question 20

define tonotopicity

Answer 20

• high tones are transmitted at beginning of cochlear swirl and low tones are transmitted at tip

Question 21

describe the neural pathway

Answer 21

dorsal and ventral cochlea nuclei

22	
describe the neural pathway 
 	 	superior olivary nuclei (synapse)
inferior colliculus  (3rd neuron)
medial geniculate body in the thalamus 
goes up to internal capsule into auditory radiation into the primary auditory cortex which sits on the superior auditory temporal lobe

Question 22

to knock out hearing completely what would have to happen?

Answer 22

you would have to knock out the entire brainstem as it ascends bilaterally

Question 23

what is the bundle of sensory fibres that travel from superior olivary nuclei to inferior colliculus

Answer 23

lateral lemniscus

Question 24

what is the function of the superior olivary nucleus

Answer 24

timing of sound waves ie knows where to look when someone clicks - left or right

Question 25

what is the function of semi-cricular canals?

Answer 25

filled with endolymph
lined with cilia
endolymph moves the cila - as a result brain knows how to keep the body balanced

Question 26

what does the utricles, saccule within the vestibule respond to?

Answer 26

changes in position of head with respect to gravity
ex) if head moves left there is increased firing from left semicircular ducts and decreased firing from right semicircular ducts

Question 27

describe the 3 vestibular pathways

Answer 27

1) vestibular ganglion –> nerve –> spinal cord in vestibulospinal tract
2) vestibular ganglion –> nerve –> vestibular nuclei –> medial longitudinal fasiculus
3) vestibular ganglion –> nerve –> vestibular nuclei –> thalamus –> cortex/ cerebellum

Question 28

what is the sensory plaque called in saccule and utricle?

Answer 28

macula - detect linear acceleration/ head position

Question 29

hair cells in vestibular apparatus are different from trochlea?

Answer 29

true as they have a baseline activity - constantly sending impulses

Question 30

how do we sweep our eyes?

Answer 30

vestibulo - ocular reflex
vestibular nuclei communicates with abducens (LR6)
and oculomotor (AO3) through the medial longitudinal fissure speaks to 3,4,6 …