Involuntary Control of Motor Units (supraspinal motor cortex and spinal reflexes)

Question 1

issue motor commands as a result of subconscious processing

Answer 1

medial and lateral pathways

Question 2

primarily controls gross movements of the trunk and proximal limbs

Answer 2

medial pathway

Question 3

medial pathway includes the:

Answer 3

1) vestibulospinal tracts
2) tectospinal tracts
3) reticulospinal tracts

Question 4

regulates involuntary control of posture and muscle tone

Answer 4

vestibulospinal tracts

Question 5

controls involuntary regulation of eye, head, neck and position in response to visual and auditory stimuli

Answer 5

tectospinal tracts

Question 6

controls involuntary regulation of reflex activity and autonomic function

Answer 6

reticulospinal tracts

Question 7

controls muscle tone and movements of the distal muscles of the upper limbs

Answer 7

lateral pathway

Question 8

lateral pathway includes:

Answer 8

rubrospinal

Question 9

has cell body towards dorsal surface of midbrain

Answer 9

tectospinal

Question 10

vestibulospinal: contra or ipsil?

Answer 10

ipsilateral all the way

Question 11

vestibulospinal tract terminates where?

Answer 11

in lamina VII and VIII

Question 12

vestibulospinal is excitatory to motor neurons of ( )

Answer 12

paravertebral and proximal limb extensor (antigravity muscles)

Question 13

the MEDIAL vestibulospinal tract descends ( ) in tract, also called ( )

Answer 13

• bilaterally

- medial longitudinal fasciculus (MLF)

Question 14

vestibulospinal tract extends only to ( ) levels

Answer 14

cervical and upper thoracic

Question 15

medial longitudinal fasciculus closely associated with ( )

Answer 15

eye movement! (yokes eye movement to head and neck position and gaze control)

Question 16

in humans, the tectospinal tract is a nerve pathway which coordinates ( )

Answer 16

head and eye movement

Question 17

the function of the tectospinal tract is to mediate ( ) of the head in response to visual and auditory stimuli

Answer 17

reflex postural movements

Question 18

decorticate posturing: disinhibition of the ( ) with facilitation of the ( )

Answer 18

• red nucleus

- rubrospinal tract

Question 19

the rubrospinal tract facilitates ( ) in the cervical spinal cord supplying flexor muscles of the upper extremities

Answer 19

motor neurons

Question 20

the rubrospinal tract and medullary reticulospinal tract biased flexion outweighs the ( )

Answer 20

medial and lateral vestibulospinal and pontine reticulospinal tract biased extension in the upper extremities

Question 21

the second component of decorticate posturing is the disruption of the lateral ( ) which facilitates motor neurons in the lower spinal cord supplying flexor muscles of the lower extremities

Answer 21

corticospinal tract

Question 22

since the corticospinal tract is interrupted, the pontine reticulospinal and the medial and lateral vestibulospinal biased extension tracts greatly overwhem ( )

Answer 22

the medually reticulospinal biased flexion tract

Question 23

decorticate posturing indicates that there may be damage to areas including the ( )

Answer 23

1) cerebral hemispheres
2) internal capsule
3) thalamus
4) midbrain

Question 24

while decorticate posturing is still an ominous sign of severe ( ), decerebate posturing is usually indicative of more severe damage as the ( ) is also involved indicating lesion where?

Answer 24

• brain damage
• rubrospinal tract (and hence the red nucleus)
• lower in the brainstem

Question 25

decerebrate posturing indicates ( ) damage, specifically damage BELOW the level of the ( )

Answer 25

- brain stem | - red nucleus

Question 26

decerebrate posture exhibited by people with lesions or compression in the ( ) and lesions in the ( )

Answer 26

midbrain; cerebellum

Question 27

progression from decorticate posturing to decerebrate posturing is often indicative of uncal or tonsilar ( )

Answer 27

brain herniation

Question 28

by definition, reflexes integrate what with what?

Answer 28

input with an output; sensation with a motor

Question 29

are reflexes important in comatose patients or awake patients?

Answer 29

both!

Question 30

muscle spindles: sensory receptors in the belly of muscles that detect ( ) and report back to CNS

Answer 30

change in muscle length

Question 31

muscle spindles are embedded in ( ) and contain 3-12 ( )

Answer 31

- extrafusal muscle fibers | - intrafusal muscle fibers

Question 32

2 types of intrafusal muscle fibers:

Answer 32

1) nuclear bag | 2) nuclear chain

Question 33

what make up muscle spindles?

Answer 33

intrafusal

Question 34

sensitivity is modulated by ( )

Answer 34

gamma motor neurons

Question 35

extrafusal controlled by ( )

Answer 35

alpha motor neurons

Question 36

intrafusal controlled by ( )

Answer 36

gamma motor neurons

Question 37

which is sensory and which is motor? extra/intrafusal

Answer 37

?

Question 38

stretch of | intrafusal sensed by sensory neurons leads to what type of activity?

Answer 38

afferent

Question 39

in voluntary activity, you activate (gamma or alpha)? why?

Answer 39

both! like a backup if strtch too much

Question 40

you can tell where the problem is on spinal cord by what?

Answer 40

deep tendon reflexes

Question 41

deep tendon reflexes: biceps

Answer 41

C5, C6

Question 42

deep tendon reflexes: brachioradialis

Answer 42

C5, C6

Question 43

deep tendon reflexes: triceps

Answer 43

C7

Question 44

deep tendon reflexes: knee

Answer 44

L3, L4

Question 45

deep tendon reflexes: ankle

Answer 45

S1, S2

Question 46

when things go wrong: upper motor neuron

Answer 46

- descending motor - lateral corticospinal - corticospinal tract

Question 47

when things go wrong: lower motor neuron

Answer 47

cell body to ??

Question 48

will a tract lesion of a corticospinal tract give you deficits below, at, or above lesion?

Answer 48

below

Question 49

UMN symptoms

Answer 49

- weakness - increased reflexes (babinski/hoffman's sign) - increased tone (spasticity) - muscle hypertrophy

Question 50

what if there is a lesion in the anterior horn?

Answer 50

this is not a tract, they are cell bodies, only thing wrong is AT the level of the lesion

Question 51

LMN vs UMN: which one wins?

Answer 51

LMN always trumps UMN