Hearing and Balance Pathways

Question 1

What does the primary auditory pathway begin with?

Answer 1

The inner hair cells in the cochlea

Question 2

Where do the afferent neurons terminate?

Answer 2

The cochlear nuclei in the pons

Question 3

How many cochlear nuclei are there?

Answer 3

4- 2 dorsal and 2 ventral

Question 4

Where are the dorsal cochlear nuclei located?

Answer 4

One either side of the midline

Question 5

What are the dorsal cochlear nuclei mainly concerned with?

Answer 5

Tone

Question 6

Where do most of the dorsal cochlear nuclei output neurons project to?

Answer 6

The contralateral inferior colliculus

Question 7

What are the Ventral cochlear nuclei mainly concerned with?

Answer 7

Intensity

Question 8

Which nerve fibres input into the anterior VCN?

Answer 8

fast Type 1 nerve fibres

Question 9

What are the subtypes of bushy cells?

Answer 9

2- Spherical BC and Globular BC

Question 10

Where do most of the anterior VCN project to?

Answer 10

The superior olivary nucleus through the trapezoid body

Question 11

What does the superior olivary complex comprise of?

Answer 11

Three primary nuclei- medial superior olivary, lateral superior olivary and medial nucleus of trapezoid body

Question 12

What is the MSO sensitive to?

Answer 12

time difference in arrival of sounds from different ears

Question 13

What is the LSO sensitive to?

Answer 13

the difference in sound intensity between the ears

Question 14

What are the lateral lemnisci formed from?

Answer 14

From fibres arising from dorsal and ventral cochlear nuclei and from the superior olivary nuclei

Question 15

Where does the lateral lemniscus terminate?

Answer 15

The central nucleus of the inferior colliculus

Question 16

Where does the lateral lemniscus send contralaterals to?

Answer 16

Cranial Nerves CNV (trigeminal) and CNVII (facial nerve)

Question 17

Where are the inferior colliculi located?

Answer 17

Either side of the midline in the lower brain

Question 18

What connects the inferior colliculi to the mediate geniculate body of the thalamus?

Answer 18

The inferior brachium

Question 19

What is the medial geniculate body?

Answer 19

The specific thalamic nucleus . for hearing

Question 20

Where do fibres of the Medial Geniculate Nucleus travel to?

Answer 20

The primary auditory cortex in temporal lobe

Question 21

What does the primary auditory cortex respond to?

Answer 21

Auditory stimuli within the contralateral sound field

Question 22

Why does lateral lemniscus send fibres to nuclei of trigeminal and facial nerves?

Answer 22

These nerves supply tensor tympani and stapedius- muscles exert dampening action on ossicles of middle ear to dampen loud noise

Question 23

What is the startle response mediated by?

Answer 23

Outputs from reticular formation to spinal cord and to motor nucleus of facial nerve- sudden loud noises causes subject to flinch e.g. alarm clock

Question 24

What do fibres entering the medial longitudinal fasciculus mediate?

Answer 24

Head turning reflex

Question 25

Where does the balance pathway begin?

Answer 25

1st order neurons in semicircular canals

Question 26

Where is the vestibular nuclei located?

Answer 26

In the pons

Question 27

What is the function of the lateral vestibulospinal tract?

Answer 27

Keeps centre of gravity between feet

Question 28

Which muscle reacts when a person vocalises normally to reduce sound intensity?

Answer 28

Stapedius

Question 29

Unexpectedly loud noises cause reflex stimulation of nuclear groups controlling which muscles?

Answer 29

Stapedius and tensor tympani

Question 30

What is the tectospinal tract involved in?

Answer 30

Coordination of head and eye movements

Question 31

Where is primary auditory cortex located?

Answer 31

Anterior two transverse gyri of temporal lobe (gyri of Heschl)

Question 32

How many vestibular nuclei are there in the lower medulla and pons?

Answer 32

4- superior, inferior, medial and lateral

Question 33

What is function of medial vestibular nucleus?

Answer 33

Contributes fibres to ipsilateral medial longitudinal fasiculus- integrates movements directed by gaze-centre and generates some head-turning reflexes

Question 34

What is the vestibulo-ocular reflex?

Answer 34

Reflex eye movement that stabilises images on retina during head movement by producing eye movement in opposite direction to head movement