Physiology 7: Spinal Reflexes, UMNs and Control of Movement

Question 1

name the motor spinal tracts that run down the LATERAL pathway

Answer 1

corticospinal (main)

rubrospinal

Question 2

name the motor spinal tracts that run down the VENTROMEDIAL pathway

Answer 2

vestibulospinal
tectospinal
reticulospinal (medial and lateral)

Question 3

spinal tracts that take the lateral pathway are under control of what part of the brain?

Answer 3

cerebral cortex

Question 4

lateral pathways mainly control..

Answer 4

voluntary control of distal muscles

Question 5

ventromedial pathways mainly control…

Answer 5

posture and locomotion

Question 6

spinal tracts that take the ventromedial pathway are under control of what part of the brain?

Answer 6

brainstem

Question 7

cell bodies of the corticospinal tract are located in..

Answer 7

motor cortex (most)
somatosensory areas of the parietal cortex

Question 8

where does the corticospinal tract’s pyramids form?

Answer 8

medulla

Question 9

why does the corticospinal tract divide into lateral and ventral?

Answer 9

most fibres split at the pyramidal decussation and go more laterally, the ones that dont stay more central

Question 10

where are the rubrospinal tract’s cell bodies located?

Answer 10

red nucleus in the midbrain

Question 11

decussation point of the rubrospinal tract?

Answer 11

ventral tegmental decussation

Question 12

where is the rubrospinal tract in relation to the corticospinal tract?

Answer 12

anterolateral

Question 13

what does the rubrospinal tract do?

Answer 13

excites LMNs of limb flexors

Question 14

a lesion in the lateral pathways could cause what? what would it NOT affect?

Answer 14

loss of single movements of body parts
slow, impaired voluntary movements
POSTURE IS FINE

Question 15

cell bodies of the vestibulospinal tract are located where?

Answer 15

lateral and medial vestibular nuclei

Question 16

where specifically do the axons from the lateral and medial vesibular nuclei go? where do they terminate?

Answer 16

lateral- descend ipsilaterally in the lateral VS tract to the LUMBAR spinal cord
medial- descend in the medial VS tract as far to the CERVICAL spinal cord

Question 17

cell bodies of the tectospinal tract reside where?

Answer 17

superior colliculus

Question 18

the superior colliculus recieves input from…

Answer 18

visual cortex and retina

Question 19

where do the tectospinal tract’s axons decussate?

Answer 19

DORSAL tegmental (not segmental) decussation

Question 20

the tectospinal tract is very medial T or F

Answer 20

T

Question 21

where does the tectospinal tract terminate and why?

Answer 21

cervical spinal cord as it is there to supply neck and shoulder muscles for the body to respond to visual stimuli eg moving head

Question 22

which reticulospinal tract is for contraction of lower limbs

Answer 22

medial

Question 23

which reticulospinal tract is for reflex control

Answer 23

lateral

Question 24

the medial RS tract descends __laterally and the lateral RS tract descends __laterally

Answer 24

ipsi

bi

Question 25

name 4 ways that spinal interneurons receive innervation

Answer 25

via:
sensory afferents eg 1a/1b
descending axons from brain
LMN branches
other interneurons

Question 26

these nerve cells can be excitatory or inhibitory and have a role in coordinating control of flexion and extension…

Answer 26

spinal interneurons

Question 27

the myotatic reflex depends on what other than the extensor muscle itself?

Answer 27

the extensor’s antagonist flexor muscle MUST be relaxed! eg quadriceps antagonist is the hamstrings

Question 28

contraction of a muscle during a reflex is caused by what nerves?

Answer 28

innervation from excitatory interneurons

Question 29

inhibition of a muscle during a reflex is caused by what nerves?

Answer 29

inhibitory interneurons