Anatomy of Auditory and Visual Pathways

Question 1

How many turns is the cochlea?

Answer 1

2.5

Question 2

Long strings….

Answer 2

Low tone

think ‘L for L’

Question 3

Short strings…

Answer 3

High tone

Question 4

What cranial nerve is responsible for hearing?

Answer 4

CN VIII

Vestibulocochlea

Question 5

Name the auditory ossicles of the middle ear.

Answer 5

Malleus
Incus
Stapes

Question 6

Where are inner and outer hair cells found?

Answer 6

Organ of Corti

Question 7

Describe the spiral ganglion.

Answer 7

Bipolar neurones stimulated by hair cells and carrying AP’s from Organ of Corti to cochlear nuclei in the pons

Question 8

Input above what level of the spinal cord is bilateral? Why?

Answer 8

Input superior to the cochlear nuclei

Here, some fibres are crossed and some are not

Question 9

What are the SUPERIOR OLIVARY NUCLEUS + NUCLEUS OF LATERAL LEMISCUS important for?

Answer 9

Important in sound localisation

Important as relays for stapedial and tensor tympany reflexes

Question 10

Where is the primary auditory cortex located?

Answer 10

Laterally, just inferior to the lateral fissure

Question 11

Where is tonotopic organisation present?

Answer 11

Auditory cortex

Question 12

Where do fibres carrying information regarding low frequency sound end?

Answer 12

In the anterolateral part of the auditory cortex

Question 13

Where do fibres carrying information regarding high frequency sound end?

Answer 13

In the posteromedial part of the auditory cortex

Question 14

What is aphasia?

Answer 14

The inability to use language

Question 15

Describe how a person may be affected by damage to Broca’s area.

Answer 15

Difficulty in producing language, often using few words and only saying the most important words in a sentence.
Do not usually have difficulty comprehending language.
Termed: Broca’s, motor or expressive aphasia

Question 16

Describe how a person with damage to Wernicke’s area may present.

Answer 16

Difficulty comprehending language.
Can manifest defects ranging from words out of order to meaningless words.
Termed: Wernicke’s, sensory or receptive aphasia.

Question 17

What does the maintenance of equilibrium use information from?

Answer 17

Vision.
Proprioception.
Vestibular apparatus (Labyrinth).

Question 18

What CN is responsible for balance?

Answer 18

CN VIII - vestibular

Question 19

What cranial nerves receive significant input from vestibular nuclei?

Answer 19

III, IV, VI

Question 20

Describe what the projection of vestibular information onto the cerebral cortex is like.

Answer 20

Bilateral

Less well defined than for other senses

Question 21

What do areas upon which vestibular information has been found to converge include?

Answer 21

 An area of parietal cortex, just posterior to the area of the postcentral gyrus that represents the hand and mouth.
 An area just rostral to the primary auditory cortex.
 Posterior insular cortex

Question 22

THERE IS NO REGION OF THE BRAIN THAT IS ACTIVATED JUST BY VESTIBULAR STIMULATION. What does this mean?

Answer 22

There is no primary vestibular cortex

Question 23

Name the 3 ‘coats’ surrounding the eye?

Answer 23

Corneoclearal - OUTER
Choroid - MIDDLE
Retina - INNER

Question 24

Because of the LENS, what happens to objects that are projected onto the retina?

Answer 24

They are UPSIDE down and REVERSED

Question 25

Something that’s in the temporal visual field of the right eye is projected onto the nasal part of the right retina

Answer 25

TRUE

Question 26

What does the optic tract 'look' at?

Answer 26

The contralateral visual field

Question 27

After the optic chiasm, outline the pathway through which visual information flows

Answer 27

1. Optic tract 2. Lateral geniculate nucleus (of thalamus) 3. Optic radiation 4. Visual cortex

Question 28

After the optic chiasm, all structures deal with information from?

Answer 28

The contralateral visual field

Question 29

Where does the superior colliculi receive input from?

Answer 29

Visual cortex Frontal eye fields Spinal cord

Question 30

What does the superior colliculi provide output to?

Answer 30

Nuclei of CN III, CN IV and CN VI Motor nucleus of CN VII Spinal cord

Question 31

Where is the lower visual field projected?

Answer 31

To the gyrus superior to the calcarine sulcus

Question 32

Where is the upper visual field projected to?

Answer 32

To the gyrus inferior to the calcarine sulcus

Question 33

Where does the macular project to?

Answer 33

To the posterior pole of the visual cortex

Question 34

Centre of vision....

Answer 34

Posterior

Question 35

Lateral of vision....

Answer 35

Anterior

Question 36

The macula occupies a much greater proportion of the cortex, relative to the size of the visual field it covers

Answer 36

TRUE

Question 37

The right hemisphere receives information from the right visual lobe

Answer 37

FALSE | From the left visual lobe

Question 38

What does the visual area above the calcarine sulcus receive retinal projections from?

Answer 38

The upper right retinal quadrant

Question 39

What does the visual area below the calcarine sulcus receive retinal projections from?

Answer 39

The LOWER RIGHT retinal quadrant. (makes sense because receives info from the upper visual field which is interpreted by the lower part of the retina!!!)

Question 40

What do fibres of the GENIOCALCARINE TRACT initially form?

Answer 40

Part of the internal capsule

Question 41

What do the fibres of the geniocalcarine tract which carry information from the UPPER HALF of the visual field first do?

Answer 41

Loop ANTERIORLY around the TEMPORAL part of the LATERAL VENRICLE in Meyer’s loop, ending below the calcarine sulcus.

Question 42

What both have roles in eye movement?

Answer 42

The visual cortex and the frontal eye fields

Question 43

In general, the visual cortex provides for movements in response to what?

Answer 43

Visual stimuli e.g tracking a moving object

Question 44

What do frontal eye fields control?

Answer 44

'Movements of command' - movements that are independent of a moving stimuli

Question 45

Describe the pupillary light reflex.

Answer 45

Shine light into right eye: Right pupil constricts = direct light reflex Left pupil constricts = consensual light reflex

Question 46

Where do perceptual fibres project BILATERALLY to?

Answer 46

The Edinger-Westphal nucleus

Question 47

What does the accommodation reflex require?

Answer 47

Input to oculomotor and Edinger-Westphal nucleus from the visual cortex

Question 48

What is the accommodation reflex?

Answer 48

Convergence of gaze, contraction of ciliarly muscles, pupillary constriction

Question 49

If vision is lost in the same visual field in both eyes, what is this known as?

Answer 49

Homonymous

Question 50

If vision is lost in different visual fields in each eye, what is it known as?

Answer 50

Heteronymous

Question 51

What do association fibres do?

Answer 51

Connect cortical sites lying in the same hemispheres

Question 52

What do commissural fibres do?

Answer 52

Connect one hemisphere to the other (usually areas of similar function)

Question 53

What do projection fibres do?

Answer 53

Connect hemispheres to deeper structures, including thalamus, corpus striatum, brain stem and spinal cord