10: Anatomy - Auditory, vestibular and visual pathways

Question 1

Which cranial nerve is responsible for hearing?

Answer 1

Cochlear part of CN VIII

Question 2

Which specialised cells are responsible for picking up vibrations in the inner ear?

Where exactly are they found?

Answer 2

Hair cells

Scala media in the Organ of Corti

Question 3

Which type of nerve fibre is closely related to hair cells in the cochlea and converts vibrations to action potentials?

Answer 3

Special sensory fibres of CN VIII

Question 4

Where do special sensory fibres of the inner ear synapse before travelling to the brain?

Answer 4

Spiral ganglia

Question 5

In which two parts of the brainstem do the special sensory neurons of CN VIII synapse?

Answer 5

Cochlear nuclei in the PONS

Inferior colliculus in the MIDBRAIN

Question 6

Which nerve bodies do special sensory fibres from the ear synapse at in the

a) inner ear
b) pons
c) midbrain

before passing to the auditory cortex of the brain?

Answer 6

a) Spiral ganglion

b) Cochlear nucleus

c) Inferior colliculus

Question 7

In which lobe is the primary auditory cortex found?

Answer 7

Temporal lobe

Question 8

At which point do fibres from the auditory pathway decussate?

Answer 8

After the cochlear nucleus

Question 9

Do all auditory pathway fibres cross over after the cochlear nucleus?

Answer 9

No

So after this the pathway is bilateral

Question 10

After the cochlear nucleus, the auditory pathway for each side of the brain contains fibres from the (ipsilateral / contralateral) side.

Answer 10

both

so the pathway is bilateral; info from both ears is processed on both sides

Question 11

What does tonotopy mean in relation to the auditory pathway?

Answer 11

Different frequencies of sound are processed by different parts of the primary auditory cortex

Question 12

What named area is found in the primary auditory cortex?

Answer 12

Wernicke’s area

Question 13

What named area is found in the posterior frontal lobe?

Answer 13

Broca’s area

Question 14

Which named area of the brain is damaged to cause difficulty comprehending language?

Answer 14

Wernicke’s area of the primary auditory cortex

Question 15

What is difficulty comprehending language called?

Answer 15

Wernicke’s aphasia

Question 16

Which named area is damaged to cause a difficulting producing language?

Answer 16

Broca’s area in the posterior frontal lobe

Question 17

What is difficulty producing language called?

Answer 17

Broca’s aphasia

Question 18

What is difficulty

a) producing

b) comprehending

language called?

Which areas of the brain are damaged to cause these diseases?

Answer 18

a) Broca’s aphasia - posterior frontal lobe

b) Wernicke’s aphasia - primary auditory cortex (temporal lobe)

Question 19

Which cranial nerve is responsible for balance?

Answer 19

Vestibular part of CN VIII

Question 20

Which cranial nerve is responsible for vision?

Answer 20

CN II - Optic nerve

Question 21

What is unusual about the nerve arrangement of the retina?

Answer 21

Light needs to pass through all the ganglia and axons to reach photoreceptors

Question 22

What are the two types of photoreceptor found in the eye?

Answer 22

Rods

Cones

Question 23

Which type of light is picked up by rods?

Answer 23

Black and white; low light

High acuity - so subtle movements but not in much detail

Question 24

Which type of light is picked up by cones?

Answer 24

Colour

Low acuity

Question 25

Which **side of the brain** is information from the **right visual field** processed on?

Answer 25

**Left**

Question 26

Which **side of the brain** is information from the **left visual field** processed on?

Answer 26

**Right side**

Question 27

At which structures in the **visual pathway** do nerve fibres a) **cross over** b) **synapse?**

Answer 27

**a) Optic chiasm** **b) Lateral geniculate nucleus**

Question 28

Where does the first **synapse** in the visual pathway occur?

Answer 28

**Lateral geniculate nucleus**

Question 29

What are the **paired structures**, found in the midbrain, which are involved in **vision** and **hearing**? Which is involved in each sense?

Answer 29

**Superior and inferior colliculi** Vision - **superior colliculus** Hearing - **inferior colliculus**

Question 30

What is the **end-point** of the **visual pathway?** Where in the brain is it found?

Answer 30

**Visual cortex** Posterior occipital lobe

Question 31

Which feature of the occipital lobe is the **visual cortex** found around?

Answer 31

**Calcarine sulcus**

Question 32

Where in the brain is the a) **visual cortex** b) **auditory cortex** found?

Answer 32

**a) Posterior occipital lobe** **b) Temporal lobe**

Question 33

Which areas of the **visual cortex** process a) **the superior visual field** b) **the inferior visual field**?

Answer 33

**a) INFERIOR visual cortex** (below the calcarine sulcus) **b) SUPERIOR visual cortex** (above the calcarine sulcus)

Question 34

Which **visual fields** are processed by the ## Footnote **a) visual cortex ABOVE the calcarine sulcus** **b) visual cortex BELOW the calcarine sulcus?**

Answer 34

**a) Inferior visual field** **b) Superior visual field**

Question 35

Where does information from the **macula** get processed?

Answer 35

**Posterior pole of the visual cortex** same arrangement re: superior and inferior

Question 36

Which areas of the brain are involved in a) **hearing** b) **balance** c) **vision**?

Answer 36

**a) Primary auditory cortex** - temporal lobe **b) Loads of areas, doesn't seem that important** **c) Primary visual cortex** - occipital lobe

Question 37

In terms of the **visual pathway**, what is **Meyer's loop**? Which structure of the brain does it go around?

Answer 37

**The part of the tract processing UPPER VISUAL FIELD info, running from the lateral geniculate nucleus to the visual cortex** **Lateral ventricle**

Question 38

What is the clinical significance of **Meyer's loop**?

Answer 38

**Because of its weird course, it can be damaged in surgery** **e.g temporal lobe surgery re: epilepsy**

Question 39

What **visual field defect** will a patient get if **Meyer's loop** is damaged?

Answer 39

**"Pie in the sky" defect** A **superior homonymous quadrantanopia**, because it processes superior visual field info on the contralateral side for both eyes

Question 40

Which **nucleus** is for **pre-synaptic parasympathetic fibres** from **CN III** and is involved in the **pupillary light reflex**?

Answer 40

**Edinger-Westphal nucleus**

Question 41

Is the **pupillary light reflex** unilateral or bilateral?

Answer 41

**bilateral**

Question 42

If a **visual pathway lesion** involves the visual cortex (i.e occurs towards the end of the pathway), what will be seen in the visual field defect?

Answer 42

**Macular sparing**

Question 43

What specific parts of the brain are responsible for **a) most motor stuff** **b) most sensory stuff** **c) processing of motor and sensory signals before sending them to the cerebrum** **d) alteration of motor signals to fit reality** **e) hearing** **f) vision?**

Answer 43

**a) Motor** - pre-central gyrus of frontal lobe **b) Sensory** - post-central gyrus of occipital lobes **c) Processing/Relay** - thalamus **d) Alteration** - cerebellum **e) Hearing** - primary auditory cortex; temporal lobes **f) Vision** - primary visual cortexl occipital lobe