Nervous system: Motor systems

Question 1

What is the function of the pre central gyrus?

Answer 1

It is the primary motor cortex and control nerve stimulation for muscle movement

Question 2

Where does the information from the primary motor cortex go?

Answer 2

It goes down the spinal cord to another neuron (FYI this neuron then takes the info to specific muscles)

Question 3

What are the cell-bodies in the primary motor cortex called?

Answer 3

Pyramidal cells

Question 4

What are some properties of pyramidal cells?

Answer 4

They are very large, they look like triangular cells with a prominent axon off them and are heavily myelinated

Question 5

How long are pyramidal cells?

Answer 5

Up to a meter + long

Question 6

Why are pyramidal cells very large?

Answer 6

They have to drive neural signals over a very large distance

Question 7

What kind of representation is on the primary motor cortex?

Answer 7

A homunculus representation

Question 8

If our motor planning area was damaged, what specific areas would be impacted? How would this affect our ability to move?

Answer 8

Broca’s, Frontal eye filed and Exners area’s

We would have only very coarse movements

Question 9

What about pyramidal cells makes them good at transmitting neural information over long distances?

Answer 9

They are very large so can generate a large current

They are heavily myelinated so that the charge is not lost over the distance

Question 10

On this diagram you can see that there is a large bulge in the middle, what is this called? Why is there this large bulge?

Answer 10

Pons

It is because this is where the cranial nerves, neves that go to the face, exit and there are lots of nerves and cell-bodies involved in this therefore lots of space necessary

Question 11

What does corticospinal mean?

Answer 11

It means that the nerves go from the cortex to the spinal cord

Question 12

Where does most of the desiccation of the corticospinal tract occur?

Answer 12

In the pyramid of lower medulla oblongata

Question 13

What is the medulla oblongata?

Answer 13

Region of nerual tissue in the brain stem that control autonomic functions

Question 14

How much of the pyramidal cells decussate at the lower medulla oblongata?

Answer 14

~85%

Question 15

Where does the pyramidal tract that decussates at the medulla go down?

Answer 15

Goes down into the lateral corticospinal tract in the spinal cord

Question 16

What does the pyramidal tract that did no decussate at the medulla go down?

Answer 16

Goes down the ventral corticospinal tract

Question 17

Where does the pyramidal tract that goes down the ventral corticospinal tract decussate?

Answer 17

In the spinal segmental level

Question 18

Label the diagram

Answer 18

Question 19

What is the difference between and upper motor neutron and a lower motor neuron?

Answer 19

An upper motor neurone (i.e. pyramidal cell) is in the cortex while a lower motor neurons are in the spinal segmental level

Question 20

How are lower motor neurons utilised in transmitting motor information? How do these signal then get transmitted to the body?

Answer 20

1 - Information from the upper motor neurons travels down the pyramidal tract

2 - ~85% of these decussate and go down the lateral corticospinal tract to the spinal segmental level needed

3 - Once in the spinal segmental level it this synapses across to the lower motor neuron in the spinal cord

4 - From the lower motor neurons it goes out the ventral root to the muscles

Question 21

What are cranial nerves?

Answer 21

Nerves that control facial muscles

Question 22

From the Primary motor cortex, where do the cranial nerves go?

Answer 22

They go down the pyramidal tract but deviate off at the pons (don’t go down spinal cord)

Question 23

What do the ventral cotricospinal tract nerves generally control?

Answer 23

The core muscles (i.e. back, core…)

Question 24

What do the lateral corticospinal tract nerves generally control?

Answer 24

The peripheral muscles (i.e. arms, hands, legs…)

Question 25

Label the diagram

Answer 25

Question 26

What is the function of the substantia nigra? Why is it called nigra (i.e. black)?

Answer 26

It is the primary cells that produce dopamine

It is full of heavily pigmented cells

Question 27

What the function of the internal capsule?

Answer 27

It carrier motor neurons to the spinal cord

Question 28

What kind of animals have a caudate nucleus and putamen? What kind of animals don’t and what do they have instead?

Answer 28

Primates (i.e. more advanced mammals)

Rodents (i.e. less advanced mammals), they instead have a striatum (FYI the caudate nucleus and putamen in primates can also be considered a striatum but they are, unlike rodents, can be distinctly separated)

Question 29

In rodents, what does the striatum look like compared to primates?

Answer 29

The nerves are much more disorganised

Question 30

What representation does the internal capsule have on the horizontal cut of the brain?

Answer 30

A homunculus representation

Question 31

What part of the internal capsule has the representation for the head?

Answer 31

The part of the internal capsule closest to the front (on the diagrams it would be the part closer to the top and at the bend)

Question 32

Label the diagram

Answer 32

Question 33

What is the function of glutamate, GABA and dopamine?

Answer 33

Glutamate: Main excitatory neurotransmitter

GABA (Gamma Amino Butyric Acid): Main inhibitory neurotransmitter

Dopamine: can be either, depends what receptor it binds to

Question 34

What is the basal ganglia system important for?

Answer 34

Initiating movement, mode control and fine motor skills

Question 35

What is the cerebellar cortex important for?

Answer 35

Important for the termination of movement and repetitive + ballistic (max force/high velocity) movements

Question 36

When you go from sitting down to walking, what parts of the motor system are you using through the actions of getting up and walking?

Answer 36

1 - Standing up: Basal ganglia system used as you are initiating movement

2 - Walking: Cerebellar cortex as it is a repetitive movement

Question 37

What is the function of the thalamus?

Answer 37

It refines movements (i.e. fine motor control)

Question 38

When you are learning a movement, what cortex of the motor system is being used? Why?

Answer 38

Cerebellar cortex because it is an unplanned movement mainly (FYI it is in the hind brain)

Question 39

When you have learnt a movement, what cortex of the motor system is being used? Why?

Answer 39

Cerebral cortex because it becomes a more planned action (FYI cerebral cortex includes the motor planning area)