Subcortical And Cortical Control Of Movement

Question 1

What three parts make up the brainstem?

Answer 1

• Medulla

• Pons

• Midbrain

Question 2

What are the two important brainstem nuclei group?

Answer 2

• Reticular formation

• Vestibular nuclei

Question 3

What is the function of the vestibulospinal tract?

Answer 3

It provides the sense of balance and spatial orientation for the purpose of coordinating movement with balance

Question 4

What is the function of the reticulospinal tract?

Answer 4

Maintaining tone, balance and posture (internal)

Question 5

Give an example of the reticulospinal tract in action

Answer 5

The calf muscles contracting to stabilise the body before the voluntary action of pulling against the wall with the biceps

Question 6

What are the three parts of the cerebellum?

Answer 6

• Superior cerebellar peduncle

• Middle cerebellar peduncle

• Inferior cerebellar peduncle

Question 7

What is the function of the superior cerebellar peduncle?

Answer 7

It’s an efferent (out) pathway to the red nucleus, the cortex (via the thalamus) and the superior colliculus

Question 8

What is the function of the inferior cerebellar peduncle?

Answer 8

It carries information to and from the spinal cord (and the body) and vestibular nuclei

Question 9

What is the red nucleus and why is it called that?

Answer 9

• A roughly spherical collection of cell bodies in the midbrain

• Called red because it’s extremely vascular - in fresh tissue it is distinctly pinker than the surrounding tissue

Question 10

Where does the red nucleus receive its input from?

Answer 10

Cerebellum and primary motor cortex

Question 11

What part of the spinal cord are the rubrospinal fibres in?

Answer 11

Ventrolateral part

Question 12

Where do the rubrospinal fibres terminate?

Answer 12

Primarily in the cervical and lumbar enlargements of the spinal cord

Question 13

What are the two pathways through the basal ganglia?

Answer 13

• Direct

• Indirect

Question 14

What is the function of the direct loop through the basal ganglia?

Answer 14

• Has an excitatory effect on cortex

• Net effect is pro-movement

Question 15

What is the function of the indirect loop through the basal ganglia?

Answer 15

• Has an inhibitory effect on cortex

• Net effect is anti-movement

Question 16

What does damage to the basal ganglia cause?

Answer 16

States where there is too much or too little movement (especially self-generated movements)

Question 17

What does damage to the cerebellum cause?

Answer 17

States where movements can still be made, but they are uncoordinated

Question 18

How can you demonstrate somatotropin of the motor cortex with modern equipment?

Answer 18

• Transcranial magnetic stimulation

• Stimulates the motor cortex and produces twitches of movement

Question 19

What are the four ways the main motor regions of the cerebral cortex can be identified?

Answer 19

• Neurones increase their firing rates before movements and specific features of this activity are often closely related to specific movement features

• Neurones send their axons to terminate in motor centres in the brainstem and spinal cord

• Electrical stimulation in these areas elicits movements

• Neurones send their axons to connect most densely with other motor areas

Question 20

What is the function of the primary motor cortex?

Answer 20

• Code for basic parameters of movement (i.e. force, direction, extent and speed)

• Fires around 5-100ms before movement onset

• Touch - vibration, heat, pain, pressure

• Proprioception - afferent information, including joint position sense, kinaesthesia and sensation of resistance

Question 21

What do neurones in the non-primary motor cortex do?

Answer 21

Code for the more complex aspects of movement

Question 22

What are the three parts of the motor cortex?

Answer 22

• Primary motor cortex

• Pre-motor cortex

• Supplementary motor cortex

Question 23

What is the function of the pre-motor cortex?

Answer 23

• Planning movement

• Spatial guidance of movement

• Sensory guidance of movement

Question 24

What is the function of the supplementary motor cortex (SMA)?

Answer 24

• Coordinating temporal sequences of actions

• Bimanual coordination

• Initiation of internally generated (as opposed to stimulus driven) movement

Question 25

What is the function of the posterior parietal cortex?

Answer 25

• Integration of sensory, visual information to execute complex movement in the environment

• Representations for different motor effectors (e.g. arm vs eye)

• A command apparatus for operation of the limbs, hands and eyes within immediate extrapersonal space

Question 26

What are the origins of the corticospinal tract?

Answer 26

• Primary motor cortex (30%)

• Premotor and supplementary motor cortex (30%)

• Somatosensory, parietal, cingulate cortex (40%)

Question 27

How does complexity change as you go up the brain?

Answer 27

Complexity increases