Cortical Mechanisms of Motor Control

Question 1

What are the two groups of descending pathways?

Answer 1

Pyramidal (corticospinal)
Indirect pathways

Question 2

What are the other indirect descending pathways?

Answer 2

• Rubrospinal
• Reticulospinal
• Vestibulospinal
• Tectospinal

Question 3

Where does the corticospinal tract originate?

Answer 3

Motor cortex

Question 4

Where is the primary motor cortex located?

Answer 4

Just anterior to the central sulcus

Question 5

How much of the corticospinal tract decussate at the pyramids?

Answer 5

85-90%

Question 6

What is carried along the corticospinal tract?

Answer 6

Motor commands underlying voluntary movement

Question 7

What is the anterior/ventral corticospinal tract responsible for?

Answer 7

proximal muscles

Question 8

What is the lateral corticospinal tract responsible for?

Answer 8

distal muscles

Question 9

What are the neurons that travel within the spinal chord called?

Answer 9

Upper motor neurons

Question 10

What are the neurons that carry excitation to the muscles?

Answer 10

Lower motor neurons

Question 11

What are the extrapyramidal tracts mainly responsible for?

Answer 11

Balance & posture

Question 12

Where does the rubrospinal tract originate?

Answer 12

Red nucleus

Question 13

What is the main function of the rubrospinal tract?

Answer 13

Acts as an alternative pathway to the pyramidal (corticospinal) tract for voluntary movement

Question 14

Where does the Vestibulospinal tract originate?

Answer 14

vestibular nuclei

Question 15

What is the main function of the Vestibulospinal tract?

Answer 15

Posture and supporting the body against gravity

Question 16

Where does the tectospinal tract originate?

Answer 16

Superior colliculi

Question 17

What is the main function of the tectospinal tract?

Answer 17

orienteering towards visual targets

Question 18

What is the main function of the reticulospinal tract?

Answer 18

Balance and a major alternative to the pyramidal (corticospinal) tract

Question 19

Where does the reticulospinal tract originate?

Answer 19

Reticular formation

Question 20

What does stimulation of the premotor/supplementary motor cortex do?

Answer 20

More complex movement that require higher current

Question 21

What is the premotor/supplementary motor cortex responsible for?

Answer 21

Learned movements or movement from memory

Question 22

What can primary motor cortex neurons encode for?

Answer 22

The force, direction, speed & extent of movement