Week 1 - I - Neuroanatomy 5 - Visual and Auditory Pathway

Question 1

What are the twelve cranial nerves and their nuclei? Where in the brain are the nuclei located?

Answer 1

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Question 2

Which division of the vestibulocochlear nerve is responsible for hearing and which is responsible for balance?

Answer 2

Hearing - cohchlear nerve Balance - vestibular nerve

Question 3

How many turns are present in the cochlea of the ear?

Answer 3

There are 2.5 turns present in the cochlea

Question 4

Collectively, a dendritie and an axon are known as a neurite Which type of neurone is extremely common in sensation? How many neurties does this neurone contain?

Answer 4

Bipolar neurones - has 2 neurites

Question 5

What is is the group of nerve cells that serve the sense of hearing by sending a representation of sound from the cochlea to the brain (to the cochlear nucleus)? What type of neurones are these?

Answer 5

These are the spiral ganglion They are bipolar neurones

Question 6

Where is cranial nerve 8 located?

Answer 6

This nerve is located at the pontomedullary junction of the brainstem

Question 7

The cochlea receives info from the inner hair cells This enters at the 8th cranial nerve at the pontomedullary junction Which peduncle attaching brainstem to cerebellum do the cochlear nculei lie beside?

Answer 7

They lie beside the middle peduncle

Question 8

Why is the auditory pathway said to be bilateral? Once fibres synapse in the cochlear nuclei, they travel to the superior olive nucleus in the pons Where do the fibres then travel along what tract?

Answer 8

Said to be bilateral as the cochlear nerve fibres syapase in both superior olivary nuclei (ie right and left) therefore making the pathway bilateral The fibres after reaching the superior olive nucleus travel in the lateral lemniscus to reach the inferior colliculus

Question 9

After synapsing at the inferior colliculus, where do the fibres travel to reach the auditory cortex? Where is the auditory cortex located?

Answer 9

Once synapsing at the inferior colliclus, fibres travel to the medial geniculate nucleus before travelling to the auditory cortex located in the temporal lobe - specifcally the superior temporal gyri

Question 10

Describe the audiotry pathway from cochlear nerve to auditory cortex?

Answer 10

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Question 11

The primary auditory cortex is located in the temporal lobe of the brain Which lobe of the brain is located very near to the auditory cortex? found deep to the lateral fissure

Answer 11

This would be the insular lobe

Question 12

The pimrary auditory cortex is here to reverie information but something has to process this information What is the area in the brain known as that comprehends speech and the area that produces speech knwon as?

Answer 12

Comprehension of speech - Wernicke’s area Production of speech - Boca’s area

Question 13

Aphasia Inability to use language The damage to wernicke’s or boca’s area causes types of aphasia known as?

Answer 13

Wernicke’s aphasia or sensory/receptive aphasia due to understanding Boca’s aphasia or motor/expressive aphasia due to production of the speech

Question 14

What is the area n orange, red and black known as?

Answer 14

Orange - (frontal lobe) precentral gyrus - primary motor cortex Red - central sulcus Black - (parietal lobe) postcentral gyrus - primary somatosensory cortex

Question 15

What is the area in blue and purple boxes knwon as? What are their functions? what would damage here be known as? What is the green box known as?

Answer 15

Blue box - Boca’s area - speech production Boca’s/motor/expressive aphasia Purple box - Wernicke’s area - speech comprehension Wernicke’s/sensory/receptive aphasia Green box is where the cingulate gyrus and sulcus are located Silver area is the calcarine sulcus

Question 16

What is the balance organ located within the temporal bone of the ear?

Answer 16

The vestibular labryinth

Question 17

The vestibular ganglion sits just outside of the vestibualar apparatus – there is a swelling on the vestibular nerve wich is where the vestibular ganglion sits Which cranial nerves have a close connection with the vestibular nuclei hence the movememnt of eyes during vertigo?

Answer 17

Cranial nerves III,IV, VI

Question 18

What does the uvea of the eye consist of?

Answer 18

Consits of the choroid, iris and ciliary body Choroid is highly vascular

Question 19

Where is aqueous humour produced and describe its pathway of flow?

Answer 19

Aqueous humour is produced in the ciliary body then travels into the posterior chamber of the eye before flowing through pupil & into the anterior chamber of the eye, it then travels to the uveoscleral angle where it passes through the trabecular meshwork & into the canal of schlemm

Question 20

What is the function of the aqueous humour?

Answer 20

Function - maintains intraocular pressure of the eye

Question 21

Where do fibres cross over in the optic pathway and what is the first synapse of the optic pathway for the fibres?

Answer 21

Cross over at the optic chiasm The first synapse of the optic pathway is at the lateral geniculate nucleus

Question 22

Because of the lens, objects are projected onto the retina reversed and upside down. The right visual world ends up in the left optic tract – the left visual world ends up in the right optic tract Is it the nasal or temporal reetinal fibres that cross over?

Answer 22

It is the nasal retinal fibres that cross over at the optic chiasm

Question 23

Where is the lateral geniculate nucleus located? What is the medial geniculate nucleus involved in?

Answer 23

The lateral geniculate nucleus is located in the thalamus The medial geniculate nucleus is involved in the auditory pathway

Question 24

Recap on the pathway for hearing once reached the cochlear nerve

Answer 24

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Question 25

What does the optic pathway continue as after the optic chiasm to the primary visual cortex? Where is the primary visual cortex?

Answer 25

Optic chiasm - optic tract - at the lateral geniculate nuclei becomes the parietal (upper) and temporal (lower) optic radiations before the pathway ends at the calcacrine sulcus of the occipital love where the primary visual cortex is located

Question 26

What region of the retina takes light from the centre of the visual field? If looking straight forward and there was something at the top left of the visual field, where would this light make contact with the pimary visual cortex?

Answer 26

The macula is in the centre of the visual field with the fovea centralis in the centre of it The light would make contact with the bottom right region of the primary visual cortex if looking at the top left of vision

Question 27

If looking at the calcacrine sulcus of the right hemisphere, what visual world (ie visual world of right or left eye) is the light going to be coming from? What separates the right and left lateral ventricles also?

Answer 27

Will be recieving image from the left visual world The lateral ventricles are separated by the septum pellicudum

Question 28

The lateral ventricle is basically in the way between the lateral geniculate body and the calcarine sulcus Therefore what is the loop known as where the fibres travel around the lateral ventricle? What region of the visual field does this relate to?

Answer 28

This is known as Meyer’s loop It is the temporal optic radiation that travels around Meyer’s loop - gives fibres to the superior quadrants of vision

Question 29

What does a saccadic movemment mean?

Answer 29

This is a quick simultaneous mvoement of both eyes between two points - ie when your eyes jump between points when rotating your head

Question 30

In general the visual cortex provides for movements in response to visual stimuli, for example tracking moving objects. (like tracking a finger moving in front of your face) Tracking movements tend to be smooth, while movements of command tend to be “jumpy” (saccadic). WHat region of the brain tends to control movements of command? (ie looking around a room)

Answer 30

This tends to be the frontal eye field located in the frontal lobe

Question 31

The extraocular muscles of the eye are controlled by cranial nerve What are these three cranial nerves and the muscles they supply? What are the modalities of each cranial nerve mentioned? What tract travels within the CNS connecting these nerves?

Answer 31

Oculomotor nerve - somatic motor, parasympathetics (to ciliary muscles and sphincter pupillae) - levator palpebrae superior, superior, inferior, medial rectus, inferior oblique Trochlear nerve - somatic motor - superior oblique Abducent nerve - somatic motor - lateral rectus The medial longitudinal fascicularis connects CN III,IV,VI

Question 32

What disease process can affect the MLF tract resulting in nystagmus of one eye when attempting to abduct it?

Answer 32

This would be multiple sclerosis

Question 33

When shining light into left eye and pupils constrict, what is this reflex known as? What is each eye known as?

Answer 33

Pupillary light reflex Left eye is the direct eye Right eye is the consensual eye

Question 34

Name where the defect occurs?

Answer 34

1. right optic nerve 2. optic chiasm 3. Right optic radiation

Question 35

What area of the brain is responsible for Visual tracking? Speech production? Somatic sensation? Motor sensation? Speech comprehension? Visual movement commands?

Answer 35

visual tracking - primary visual cortex - calcacrine sulcus of occipital lobe Speech production - Boca’s area Somatic sensation - primary somatosensory cortex - precentral gyrus of frontal lobe Motor sensation - primary motor cortex - postcentral gyrus of parietal lobe Speech comprehnsion – Wernicke’s area Visual movement commands - Frontal eye field

Question 36

Where is The primary visual cortex? The primary auditory cortex located?

Answer 36

Priamry visual cortex - occipital lobe (calcacrine sulcus) Primary audiry cortex - superior temporal gyrus - temporal lobe (just inferior to lateral fissure)

Question 37

Even though the two cerebral hemispheres appear similar, and receive similar inputs, in some ‘higher’ functions one hemisphere ‘takes the lead’ and we refer to this as the dominant hemisphere. The extent of dominance varies considerably, but is generally high for language functions. For most truly right handed people, what hemisphere is dominant?

Answer 37

The left hemisphere

Question 38

What are the different regions of the basal ganglia?

Answer 38

Caudate nucleus Putamen Globus pallidus Substantia nigra Subthalamic nucleus

Question 39

What separates the caudate nucleus from the lentiform nucleus? What forms the lentiform nucleus? What forms the striatum? and corpus striatum?

Answer 39

The inernal capsule separates these Lentiform nuclues - globus pallidus + putamen Striatum - putamen + caudate nucleus Corpus striatum - striatum + globus pallidus

Question 40

What other sensation cortex lies in the temporal lobe? Specifically what part of the temporal lobe?

Answer 40

Primary olfactory cortex lies in the uncus of the temporal lobe