Nervous system: Motor systems Flashcards
What is the function of the pre central gyrus?
It is the primary motor cortex and control nerve stimulation for muscle movement
Where does the information from the primary motor cortex go?
It goes down the spinal cord to another neuron (FYI this neuron then takes the info to specific muscles)
What are the cell-bodies in the primary motor cortex called?
Pyramidal cells
What are some properties of pyramidal cells?
They are very large, they look like triangular cells with a prominent axon off them and are heavily myelinated
How long are pyramidal cells?
Up to a meter + long
Why are pyramidal cells very large?
They have to drive neural signals over a very large distance
What kind of representation is on the primary motor cortex?
A homunculus representation
If our motor planning area was damaged, what specific areas would be impacted? How would this affect our ability to move?
Broca’s, Frontal eye filed and Exners area’s
We would have only very coarse movements
What about pyramidal cells makes them good at transmitting neural information over long distances?
They are very large so can generate a large current
They are heavily myelinated so that the charge is not lost over the distance
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?
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
What does corticospinal mean?
It means that the nerves go from the cortex to the spinal cord
Where does most of the desiccation of the corticospinal tract occur?
In the pyramid of lower medulla oblongata
What is the medulla oblongata?
Region of nerual tissue in the brain stem that control autonomic functions
How much of the pyramidal cells decussate at the lower medulla oblongata?
~85%
Where does the pyramidal tract that decussates at the medulla go down?
Goes down into the lateral corticospinal tract in the spinal cord
What does the pyramidal tract that did no decussate at the medulla go down?
Goes down the ventral corticospinal tract
Where does the pyramidal tract that goes down the ventral corticospinal tract decussate?
In the spinal segmental level
Label the diagram
What is the difference between and upper motor neutron and a lower motor neuron?
An upper motor neurone (i.e. pyramidal cell) is in the cortex while a lower motor neurons are in the spinal segmental level
How are lower motor neurons utilised in transmitting motor information? How do these signal then get transmitted to the body?
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
What are cranial nerves?
Nerves that control facial muscles
From the Primary motor cortex, where do the cranial nerves go?
They go down the pyramidal tract but deviate off at the pons (don’t go down spinal cord)
What do the ventral cotricospinal tract nerves generally control?
The core muscles (i.e. back, core…)
What do the lateral corticospinal tract nerves generally control?
The peripheral muscles (i.e. arms, hands, legs…)
Label the diagram
What is the function of the substantia nigra? Why is it called nigra (i.e. black)?
It is the primary cells that produce dopamine
It is full of heavily pigmented cells
What the function of the internal capsule?
It carrier motor neurons to the spinal cord
What kind of animals have a caudate nucleus and putamen? What kind of animals don’t and what do they have instead?
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)
In rodents, what does the striatum look like compared to primates?
The nerves are much more disorganised
What representation does the internal capsule have on the horizontal cut of the brain?
A homunculus representation
What part of the internal capsule has the representation for the head?
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)
Label the diagram
What is the function of glutamate, GABA and dopamine?
Glutamate: Main excitatory neurotransmitter
GABA (Gamma Amino Butyric Acid): Main inhibitory neurotransmitter
Dopamine: can be either, depends what receptor it binds to
What is the basal ganglia system important for?
Initiating movement, mode control and fine motor skills
What is the cerebellar cortex important for?
Important for the termination of movement and repetitive + ballistic (max force/high velocity) movements
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?
1 - Standing up: Basal ganglia system used as you are initiating movement
2 - Walking: Cerebellar cortex as it is a repetitive movement
What is the function of the thalamus?
It refines movements (i.e. fine motor control)
When you are learning a movement, what cortex of the motor system is being used? Why?
Cerebellar cortex because it is an unplanned movement mainly (FYI it is in the hind brain)
When you have learnt a movement, what cortex of the motor system is being used? Why?
Cerebral cortex because it becomes a more planned action (FYI cerebral cortex includes the motor planning area)
