Motor Control

Question 1

What is the highest level in the motor system?

Answer 1

The primary cortex

Question 2

What does the primary motor cortex do?

Answer 2

It projects directly into the spinal cord via the corticospinal tract
It regulates the motor tracts that originate in the brainstem

Question 3

What is the middle level in the motor system?

Answer 3

The brainstem

Question 4

What does the brainstem do?

Answer 4

It is a laterally descending system which controls distal limbs and is important for goal-directed movements of the hand and arm

Question 5

What is the lowest level of the motor system?

Answer 5

The spinal cord

Question 6

What does the spinal cord do?

Answer 6

It controls neuronal circuits that mediate reflexes automatisms such as walking as well as many other actions

Question 7

What is the symplest reflex?

Answer 7

mono-synaptic

Only involves one sensory neuron and one motor neuron

Question 8

What haooens if you artificially stimulate the motor cortex, brainstem and spinal cord?

Answer 8

You only get twitches

Question 9

What do lateral brainstem pathways control?

Answer 9

The hands and the arm

Question 10

What do direct spinal cord pathways control?

Answer 10

Muscles and reflexes

Question 11

What does the basal ganglia ‘loop’ back to and via what pathway?

Answer 11

It only feeds back to the motor cortex via the subcortical loop

Question 12

What is the role of the basal ganglia and the cerebelllum?

Answer 12

They receive information from many different areas of the cortex and they project to the motor cortex
They are aware of situations a person is in and they monitor commands to the muscle to make sure they are appropriate for the situation
If commands are not appropriate then they calculate correct signals and send this to the motor cortex

Question 13

What does the cerebellum feed back to?

Answer 13

Mainly the motor cortex but it can send signals down the brainstem and the spinal cord

Question 14

When was the motor cortex discovered?

Answer 14

1870

Question 15

In the mid 20th century electrical stimulation of the frontal lobes showed what?

Answer 15

There are specific motor effects depending on which site is stimulated in humans and primates

Question 16

How have motor maps been produced?

Answer 16

They are correlated with anatomical and clinical observations on effects of lesions

Question 17

Where is brodmanns area 4 located?

Answer 17

It is found to be in an area in which the lowest intensity stimulus elicited a movement
It is the primary motor cortex and is found infront of the central sulcus (can be called the pre central gyrus)

Question 18

Are the control areas for different parts of the body proportional to the size of the body part?

Answer 18

No because some small areas such as the hands and lips need fine motor control so their control area is disproportionally big

Question 19

What happens to the spinal cord as a result of lesions in the primary motor cortex?

Answer 19

There is degeneration in the associated spinal cord area

Question 20

What are the motor cortex’s first neurons called?

Answer 20

Upper motor neurons

Question 21

What is the role of upper motor neurons?

Answer 21

They carry motor commands down the brain, brainstem and to the spinal cord
They are involved in planning, initiating and directing movements

Question 22

What is the red nucleus/ nucleus ruber?

Answer 22

Mainly controls gait and crawling in babies

It relays information from the motor cortex to the cerebellum

Question 23

What is the vestibular nuclei?

Answer 23

Cranial nuclei for the vestibular nerve
They are grouped by the pons and the medulla in the brainstem
Function in the maintenance of equilibrium and posture, perception of the head position and acceleration as well as general muscle tone

Question 24

What is the superior colliculus?

Answer 24

Paired structure in the midbrain

Directs behavioural responses toward specific points in egocentric space eg head turning and eye movements

Question 25

What is reticular formation?

Answer 25

Has projections to the thalamus and cerebral cortex Allows some control over which sensory signals reach the cerebrum and come to our conscious attention Has a role in states of consciousness like sleep and alertness

Question 26

What has to be controlled by the motor system?

Answer 26

Muscle tone Postural muscles Maintained balance Orientation of the head and body

Question 27

Describe the upper motor neurons direct pathway

Answer 27

The neurons input to lower motor neurons from axons extending directly from the cerebral cortex

Question 28

Describe the upper motor neurons indirect pathways

Answer 28

Input to lower motor neurons from motor centres in the brainstem

Question 29

What do both of the upper motor neuron pathways do?

Answer 29

Both pathways govern the production of action potentials in the lower motor neurons, the final common pathway, that leads to muscle contraction/movement

Question 30

Why are lower motor neurons called the final common pathway?

Answer 30

These are the neurons which innervate the muscle

Question 31

What are the 4 sub areas of the basal ganglia?

Answer 31

The caudate, putamen, substantia nigra and subthalamic nuclei

Question 32

What is Gilles de la Tourette's syndrome?

Answer 32

Causes tics and vocal tics | Caused by a dysfunction in the cortical and subcortical regions and the basal ganglia

Question 33

What is the role of the cerebellum?

Answer 33

Control activity of the upper motor neurons It connects to the cortex via the thalamus and the brainstem It monitors movements for differences between intended and actual movements If there are any discrepancies it sends an error signal and tries to reduce the discrepancy