W6 - Upper Motor Neurons

Question 1

UMN cell bodies lie in the Bst and cerebral cortex, what two things can the axons synapse with?

Answer 1

LMNs directly (rare) or local circuit neurons

Question 2

What are UMN from the motor cortex responsible for?

Answer 2

Initiating and planning voluntary movements

Question 3

UMN from Bst are responsible for…

Answer 3

Basic movements and posture

Question 4

What does the cerebellum and basal ganglia do?

Answer 4

Regulate the descending tracts

Question 5

Why do white matter tracts for UPM want to be as short as possible?

Answer 5

For efficiency

Question 6

UMNs differ in where they what?

Answer 6

Terminate in the SC

Question 7

What defines the Brodmann areas?

Answer 7

Cytoarchitecture

Question 8

The dorsolateral prefrontal cortex (areas 9+46) are associated with …

Answer 8

Executive functions

Question 9

What is the highest cortical area involved with motor planning of future movements?

Answer 9

Dorsolateral prefrontal cortex

Question 10

The pre-motor cortex has sensory input from superior (touch) and ….. ….. lobe

Answer 10

Inferior (auditory) parietal lobe

Question 11

What is the main aim of the input to the pre-motor cortex? (areas 6+8)

Answer 11

Motivation for the desired outcome

Question 12

Where is the primary motor cortex located?

Answer 12

Pre-central gyrus in Brodmann’s area 4

Question 13

UMN from primary MC have thick axons, what does this mean about their connections with LMNs

Answer 13

The connections are strong

Question 14

What type of pyramidal cells are the largest neurons in the human CNS and account for ~5% of projection to the SC?

Answer 14

Betz cells

Question 15

Where are pyramidal cells found? (the UMN of the primary MC)

Answer 15

Cortical layer 5 of the primary motor cortex

Question 16

Corticobulbar axons leave the CBT at different levels of the brainstem what are these?

Answer 16

CN nuclei, reticular formation (for wakefulness) and nuclei at base of pons

Question 17

Describe the pathway of neurons in the CBT and CST

Answer 17

Internal capsule - cerebral peduncle - pons - pontine fibres

Question 18

What are the two CSTs?

Answer 18

Lateral (~90%) and ventral (~10%)

Question 19

Where do the CS axons decussate to form the Lat CST in the CS?

Answer 19

Caudal medulla

Question 20

The ventral CS axons do not what?

Answer 20

Decussate in the caudal medulla

Question 21

Which CST are involved in innervates the muscle/hand and which serve the axial/proximal limb muscles?

Answer 21

Lateral - hand/forearm, Ventral - axial/proximal limbs

Question 22

Where are spinal local interneurons found?

Answer 22

Lateral horn of SC