Disorders Of The Motor System

Question 1

What makes up the lentiform nucleus?

Answer 1

Putamen
Globus pallidus

Question 2

What makes up the striatum?

Answer 2

Caudate nucleus
Putamen

Question 3

Function of the cerebellar peduncles
What do each section connect to?

Answer 3

Connection between brainstem + cerebellum
- superior cerebellar peduncle to midbrain
- middle cerebellar peduncle to pons
- inferior cerebellar peduncle to medulla

Question 4

How does the basal ganglia communicate with the motor cortex?

Answer 4

Via thalamus

Question 5

Describe the communication between the cortex and basal ganglia
How does that affect basal ganglia signs?

Answer 5

• Cortex communicates with ipsilateral basal ganglia
• contralateral signs to damage

Question 6

Describe communication between cortex + cerebellar hemisphere
How does that affect cerebellar signs?

Answer 6

• Cortex communicates with contralateral cerebellar hemispheres
• ipsilateral sign to damage

Question 7

Role of the direct pathway

Answer 7

• reinforces appropriate movement
• excitatory on cortex

Question 8

Role of the indirect pathway

Answer 8

• inhibits inappropriate movements
• inhibitory on cortex

Question 9

Describe the effect of dopamine release from the substantia nigra

Answer 9

• SN releases dopamine
• excites direct pathway > excites cortex
• inhibits indirect pathway > inhibition of inhibition > excites cortex

Question 10

Role of sub-thalamic nucleus
How does the indirect pathway affect this?

Answer 10

• Inhibits movement
• indirect pathway inhibits the inhibtion of by globus pallidus externa STN > inhibition of inhibition > stimulation

Question 11

Signs + symptoms of cerebellar lesions in vermis

Answer 11

DANISH
- dysdiadochokinesia
- ataxia
- nystagmus
- intention tremor
- slurred speech
- hypotonia

Question 12

What can cerebellar lesion present with?

Answer 12

Vomiting
Vertigo
Difficulty walking

Question 13

What is the inheritance of Huntington’s disease?

Answer 13

Autosomal dominant

Question 14

What is Huntington’s due to?

Answer 14

• Loss of inhibitory projections from striatum to globus pallidus externa > hyperkinetic features
• CAG repeat expansions

Question 15

Presentation of Huntington’s chorea

Answer 15

• choreiform movements (looks like fidgeting)
• dystonia
• uncoordination
• psychiatric features + cognitive decline

Question 16

What is Parkinson’s disease due to?

Answer 16

Degeneration of substantia nigra dopamine neurones > hypokinetic/decreaed movement

Question 17

Triad of Parkinson’s disease presentation

Answer 17

Tremor
Lead pipe rigidity
Bradykinesia

Question 18

How can Parkinson’s disease tremor improve?

Answer 18

Can improve if you ask them to do something

Question 19

Describe Parkinsonian gait

Answer 19

• Struggle to initiate + stop movement
• Shuffling
• no arm swing

Question 20

Presentation for Parkinson’s disease

Answer 20

• tremor
• rigidity
• bradykinesia
• hypophonia (quiet speech)
• micrographica (small hand writing)
• decreased facial movement
• dementia
• depression

Question 21

What is hemiballismus?

Answer 21

Unilateral explosive movements

Question 22

What is hemiballismus due to?

Answer 22

damage to sub thalamic nucleus > loss of inhibition of thalamus via globus pallidus interna

Question 23

Anatomy of cerebellum + how this relates to function

Answer 23

• Midline vermis - trunk
• Two laterally placed hemisphere - ipsilateral body

Question 24

What is dysdiadochokinesia?

Answer 24

Difficulty with rapidly alternating movements
(Issue with rapid pronation + supination)

Question 25

Function of cerebellum

Answer 25

Sequencing + co-ordination of movements

Question 26

What is ataxia?

Answer 26

Unsteady gait due to difficulty sequencing lower limb muscle contractions + loss of unconscious proprioception from lower limbs

Question 27

What is an intention tremor?

Answer 27

Tremor that worsens as a target is approached

Question 28

What effect would stimulation of globus pallidus interna have on movement?

Answer 28

Increased inhibition of thalamus > decreased movement

Question 29

What effect would stimuation of subthalamic nucleus have on movement?

Answer 29

Increased activity in GPi > increased inhibtion of thalamus > decreased movement

Question 30

Why can upper motor neurones lead to spasticity?

Answer 30

Loss of descending inhibition to lower motor neurones

Question 31

What structure in the midbrain is important for motor control?

Answer 31

Red nucleus

Question 32

What could destruction of the subthalamic nucleus cause?

Answer 32

**Hemiballismus** Unilateral involuntary explosive movements

Question 33

Why might a stroke affecting the lateral aspect of the motor cortex compromise swallowing?

Answer 33

Denervation of cranial nerves which distribute lower motor neurones in vagus nerve

Question 34

How is a patient with Parkinson’s disease at an increased risk of DVT?

Answer 34

- flat foot shuffling gait > diminished calf pump activity - this normally helps to pump blood up the legs in veins - predisposing to DVT - also more likely to have reduced mobility