Nervous system: Sensory Systems of the Brain

Question 1

Label the diagram

Answer 1

Question 2

What is the central part of the spinal cord made of?

Answer 2

Grey matter

Question 3

What is the surrounding parts of the grey matter in the spinal cord made of?

Answer 3

White matter

Question 4

What is the grey matter made of?

Answer 4

Cell bodies

Question 5

What is white matter made of?

Answer 5

Nerve fibers

Question 6

What do the cell bodies do?

Answer 6

Decide on the neural response to signals

Question 7

What does the dorsal column do?

Answer 7

It transmits the neural information up the spinal cord into the brain

Question 8

What do funiculi, fasciculus and columns in neural material have in common?

Answer 8

They are all bundles of white matter which transmit neural information

Question 9

What is a gracile and cuneate fasciculus on one side of the spinal segment called? What are both fragile and cuneate fasciculus called?

Answer 9

Funiculi

Dorsal column

Question 10

What information does the gracile fasciculus carry? Relatively how large would the gracile fasciculus be at the bottom of the spinal cord vs the top?

Answer 10

Information from the hips down

Would be relatively large (more nerves coming from lower part of body into spinal cord)

Question 11

What information does the cuneate fasciculus carry? Relatively how large would the cuneate fasciculus be at the bottom of the spinal cord vs the top?

Answer 11

From the hip up to the neck

Would be relatively small (no nerves coming from upper part of body into spinal cord here, but further up the spinal cord it would be larger)

Question 12

What is the representation on the fasciculus called?

Answer 12

A homunculus respresentation

Question 13

Where do most encapsulated nerves connect to in the spinal cord?

Answer 13

Directly into the dorsal column

Question 14

Where some of the encapsulated nerves connect to? What process occurs here with these nerves?

Answer 14

They connect into the grey matter

Convergence

Question 15

What is the purpose of convergence?

Answer 15

It causes the signals from many nerves to become integrate into a single nerve which is then linked into the dorsal column reducing the space needed for info transfer (therefore reducing size of spinal cord)

Question 16

Where do the free nerve endings go?

Answer 16

They go into the grey matter then into the spinothalamic tract

Question 17

What does the lateral corticospinal tract do?

Answer 17

Carries information from brain to lower motor neurons

Question 18

What happens to lower motor neurons?

Answer 18

Nerves go out to muscles via the ventral root

Question 19

What is a very generalised principle about where information goes into/out of the spinal cord?

Answer 19

Information generally (though there are exceptions) goes to the brain through the dorsal side of the spinal cord, information goes out of the spinal cord through the ventral root

Question 20

Label the diagram, what kind of pathway is this describing?

Answer 20

Discriminative sensation (touch and pressure)

Question 21

Label the diagram, what kind of pathway is this describing?

Answer 21

Discriminative sensation (touch and pressure) I

Question 22

What is the function of the gracile and cuneate nuclei?

Answer 22

It is to receive all the nerve fibres from the gracile and cuneate fasciculus respectively

Question 23

What is the nerve fibre called once it has passed through the cuneate/gracile nuclei?

Answer 23

It is called the medial lemniscus

Question 24

How does the position of the medial lemniscus change as it moves up the brain?

Answer 24

It moves further back in the brain as it moves up

Question 25

How does the lateral spinothalamic tract move through the brain?

Answer 25

It moves back as it goes up the brain

Question 26

When the lateral spinothalamic tract is going to the medial lemniscus, how does it join with it? Where does it go?

Answer 26

It becomes a nerve that is NEXT TO the medial lemmiscus, goes to the thalamus

Question 27

Do the non-discriminatory and discriminatory pathways both go to the same place?

Answer 27

Not quite, they go to the same region of the cortex but are in different levels of the brain tissue

Question 28

What do the different pathways innervate?

Answer 28

Different synapses

Question 29

Label the diagram, what kind of pathway is this describing?

Answer 29

Non-discriminative

Question 30

What is decussation?

Answer 30

When the nerves cross over onto the other side of the body

Question 31

Where do the discriminative and non-discriminative neurons decussate?

Answer 31

Discriminative: Internal articulate fibres Non-discriminative: spinal cord

Question 32

If there was damage on the medial lemniscus and the lateral spionthalamic tract in the right hand side of the brain, what would be the impact?

Answer 32

There would be an associative sensory loss on the left hand side of the body for both pain/temperature and pressure/touch

Question 33

If there was damage on the medial lemniscus and the lateral spionthalamic tract in the right hand side of the spinal cord, what would be the impact?

Answer 33

There would be a dissociative sensory loss for pain/temperature on the left hand side and pressure/touch on the right hand side

Question 34

Why are the associative sensory losses for pain/temp and pressure/touch different depending on where there is damage?

Answer 34

The Dorsal funicular (pressure/touch nerve) decussates (swaps over) in the gracile/cuneate nuclei (due to internal arcuate fibres FYI) which is at the lower medulla while the lateral spinothalamic tract (pain/temp) decussates in the spinal cord. This means that the two sensation systems are not aligned with each other for part of the nervous system therefore can have different response in to the same location damage

Question 35

Where does the 1st neuron of discriminative and non-discriminative neurons terminate?

Answer 35

Discriminative: Cuneate/Gracile nuclei Non-discriminative: grey matter of spinal cord

Question 36

How does the free nerve ending get into the spinal segmental level? What does it do once in here?

Answer 36

Gets into the spinal segmental level via the dorsal root Once in the spinal level it synapses in the posterior part of the grey matter and then connects to the spinothalmaic tract

Question 37

When the free nere ending connects to the spinothalamic tract, what process is occuring?

Answer 37

Decussation (crosses over onto other side of the body)