Motor Pathways & Disorders

Question 1

What are the two divisions of motor pathways?

Answer 1

1. Lateral pathways (corticospinal, rubrospinal)
2. Ventro-medial pathways (vestibulospinal, tectospinal, reticulospinal).

Question 2

What is the main function of the corticospinal tract?

Answer 2

It provides direct cortical control of voluntary movements, especially fine movements of the limbs.

Question 3

Which structures comprise the basal ganglia? (6)

Answer 3

• caudate nucleus
• putamen
• globus pallidus (internal and external)
• substantia nigra
• subthalamic nucleus

Question 4

What is the role of the basal ganglia in movement?

Answer 4

They regulate the initiation and control of voluntary movements, balancing the DIRECT and INDIRECT pathways to facilitate desired motor programs and supress competing ones.

Question 5

Int the basal ganglia pathways, how does dopamine modulate activity? (3)

Answer 5

• D1 receptors (direct pathway): Facilitates movement.
• D2 receptors (indirect pathway): Inhibits movement.
• Dopamine from the substantia nigra helps balance these pathways.

Question 6

Which key motor roles does the cerebellum perform? (4)

Answer 6

• Coordination of movement
• Balance
• Error correction
• Motor Learning (fine-tuning and adjusting ongoing movement)

Question 7

What is Parkinson’s Disease?

Answer 7

A hypokinetic motor disorder caused by degeneration of dopaminergic neurons in the substantia nigra, leading to reduced movement initiation.

Question 8

List FOUR classic symptoms of Parkinson’s Disease

Answer 8

1. Akinesia (difficulty initiating movement)
2. Bradykinesia (slowness of movement).
3. Rigidity
4. Resting tremor (“pill-rolling” tremor)

Question 9

What pathological hallmark is found in dying dopaminergic cells in Parkinson’s Disease?

Answer 9

Lewy bodies, which are intracellular aggregates of α-synuclein.

Question 10

How does L-DOPA help in Parkinson’s Disease?

Answer 10

L-DOPA is converted to dopamine in the brain, temporarily replenishing DA levels and improving motor symptoms.

Question 11

Name TWO adjunct therapies used alongside L-DOPA in Parkinson’s treatment.

Answer 11

• MAO-B inhibitors (e.g., selegiline) to reduce DA breakdown.
• COMT inhibitors (e.g., entacapone) to prolong DA effects.

Question 12

What is Huntington’s Disease?

Answer 12

A hyperkinetic disorder characterised by chorea, caused by neuronal loss in the caudate/putamen (striatum) and a genetic mutation in the huntingtin gene.

Question 13

Which symptoms define Huntington’s Disease? (3)

Answer 13

• Chorea (involuntary jerking)
• Impaired balance and gait
• Cognitive decline and psychiatric disturbances

Question 14

How does striatal degeneration in Huntington’s Disease affect movement?

Answer 14

Reduced inhibition of the thalamus leads to excessive thalamo-cortical activity, resulting in involuntary, hyperkinetic movements.

Question 15

What pharmacological strategies exist for Huntington’s Disease? (3)

Answer 15

Symptomatic Treatments:

• Antipsychotics or D2 receptor agonists for chorea
• Baclofen (muscle relaxant)

Question 16

What is the primary function of the cerbellum in motor control?

Answer 16

It coordinates and fine-tunes motor activity, ensuring smooth, accurate movements and adaptation through motor learning.

Question 17

Define cerebellar ataxia

Answer 17

A coordination disorder resulting from cerebellar dysfunction, leading to impaired balance, gair, and fine motor control.

Question 18

Mention TWO possible causes of cerebellar degeneration

Answer 18

• Genetic (spinocerebellar ataxias).
• Acquired (trauma, stroke, chronic alcohol use, certain drugs).

Question 19

How do lesions in the basal ganglia differ from cerebellar lesions in motor symptoms? (2)

Answer 19

• Basal ganglia lesions: Lead to either reduced movement (Parkinson’s) or excessive movement (Huntington’s)
• Cerebellar lesions: Lead to ataxia, poor coordination, and inability to correct motor errors.

Question 20

What is deep brain stimulation (DBS), and how is it used in Parkinson’s Disease?

Answer 20

An implanted device delivers electrical impulses to targets like the subthalamic nucleus, helping modulate basal ganglia output and improve motor symptoms.