Lesion localisation - UMN vs LMN

Question 1

Where do the motor pathways for voluntary movement run from?

Answer 1

• the motor cortex in the forebrain to the effector muscle
• irrespective of the pathways all pathways involve a final common pathway - the lower motor neurone

Question 2

What does a lower motor neurone consist of?

Answer 2

• a cell body in the grey matter of the spinal cord
• an axon which projects via the ventral root of segmental nerve to the effector muscle

Question 3

What is the LMN the final common pathway for?

Answer 3

• voluntary motor activity

Question 4

What is a LMN needed for?

Answer 4

• reflexes
• to maintain tone

Question 5

What is. UMN needed for? What is is not needed for?

Answer 5

• need for voluntary motor activity
• not needed for reflexes
• not needed to maintain tone

Question 6

CS of LMN damage

Answer 6

• paresis/paralysis
• reduced tone or flaccid
• reduced or absent segmental reflexes

Question 7

CS of UMN damage

Answer 7

• paresis/paralysis
• retained or increased tone
• retained or increased segmental reflexes