Control of Movement

Question 1

function of alpha motoneurons

Answer 1

activate main (extrafusal) muscle fibers to contract

Question 2

muscle spindle afferent function

Answer 2

signal muscle length changes

Question 3

extrafusal

Answer 3

outside the muscle spindle

Question 4

intrafusal

Answer 4

inside the muscle spindle

Question 5

golgi tendon organ afferents function

Answer 5

signal muscle force

Question 6

gamma motoneuron function

Answer 6

increases the sensitivity of muscle spindles to length changes of the parent muscle

Question 7

how do gamma motoneurons increase spindle sensitivity

Answer 7

by activating intrafusal fibers which stretch spindles and causes sensory afferents to fire more rapidly

Question 8

what is the gamma loop responsible for

Answer 8

maintaining muscle tension during movement

Question 9

theory of alpha-gamma coactivation

Answer 9

intrafusal contraction compensates for spindle shortening

- this keeps spindle afferent firing rate constant

Question 10

reality of alpha-gamma coactivation

Answer 10

spindle afferent firing does decrease, because gamma motoneurons are not enough compensation

Question 11

2 spinal cord reflexes

Answer 11

1. stretch reflex

2. flexor withdrawal reflex

Question 12

stretch reflex stimulus

Answer 12

muscle stretch

Question 13

what 2 things simultaneously occur during the stretch reflex

Answer 13

1. spindle-afferent-mediated monosynaptic excitation of agonist motoneurons and disynaptic inhibition of antagonist motoneurons
2. tendon-organ-mediated disynaptic inhibition of agonist motoneurons and disynaptic excitation of antagonist motoneurons

Question 14

what opposes change in muscle length

Answer 14

excitation of agonist MN’s and disynaptic inhibition of antagonist MN’s

Question 15

what opposes change in force

Answer 15

inhibition of agonist MN’s and disynaptic excitation of antagonist MN’s

Question 16

purpose of stretch reflex

Answer 16

to resists imposed force in a spring-like manner

Question 17

what causes the flexor withdrawal reflex

Answer 17

stepping on something painful

Question 18

flexor withdrawal reflex

Answer 18

noxious stimulation (pain) causes flexion of ipsilateral leg and extension of contralateral leg

Question 19

another name for the primary motor cortex, and why?

Answer 19

sensorimotor cortex, because of the importance of sensory signals

Question 20

what controls complex movements of extremities

Answer 20

major motor areas of cerebral cortex

Question 21

somatotopic map

Answer 21

somatotopic representation similar to the topographic map on the somatosensory cortex

Question 22

where is the somatotopic map located

Answer 22

in the primary motor cortex

Question 23

how was the somatotopic map established

Answer 23

with electrical stimulation with a probe during brain operations

Question 24

which regions of the body occupy the largest areas of the somatotopic map

Answer 24

face and hands

Question 25

how can neurons in the primary motor cortex be activated

Answer 25

with transcranial magnetic stimulation (TMS)

Question 26

how is TMS stimulating the primary motor cortex useful

Answer 26

useful in spinal cord operations to check for conduction block

Question 27

what is another name for the pyramidal tract (PT)

Answer 27

the corticospinal tract (CST)

Question 28

corticospinal tract

Answer 28

axons from neurons in sensorimotor cortex make the tract | - these neurons make monosynaptic connections with spinal alpha motoneurons

Question 29

what results from CST lesions

Answer 29

spastic hemiplegia

Question 30

spastic hemiplegia symptoms (5)

Answer 30

1. weakness or paralysis of extremities 2. exaggerated stretch reflexes 3. spasms 4. speech deficits 5. attentional deficits

Question 31

paresis

Answer 31

weakness

Question 32

hypertonus

Answer 32

exaggerated stretch reflex

Question 33

dysarthria

Answer 33

motor speech disorder

Question 34

aphasia

Answer 34

disturbance in language comprehension

Question 35

apraxia

Answer 35

inability to execute learned purposeful movements

Question 36

hemi-neglect

Answer 36

inability to attend to one side of space

Question 37

upper motoneuron lesions

Answer 37

another name for CST lesions

Question 38

Broca's area function

Answer 38

motor aspects of speech

Question 39

lesion in Broca's area

Answer 39

motor aphasia (slurring speech)

Question 40

Wernicke's area functions (2)

Answer 40

1. comprehension of language | 2. association of visual, auditory, and tactile input with words

Question 41

lesions in Wernicke's area

Answer 41

sensory aphasia and dyslexia

Question 42

what would happen if you handed a person with sensory aphasia a pen

Answer 42

they might think it's a spoon, but proceed to write their name with it

Question 43

what does sensory aphasia tell us about brain pathways

Answer 43

sensory to motor transformation is separate from sensory to cognitive transformation

Question 44

2 inputs to cerebellum

Answer 44

1. sensory input from spinal cord | 2. motor commands from cerebral cortex

Question 45

4 functional divisions of the cerebellum

Answer 45

1. vermis 2. intermediate zone 3. lateral zone 4. flocculondular lobe

Question 46

vermis

Answer 46

posture, neck and axial musculature

Question 47

intermediate zone

Answer 47

locomotion

Question 48

lateral zone

Answer 48

coordinating complex | - skilled movements of arms, hands, and fingers

Question 49

flocculonodular lobe

Answer 49

balance

Question 50

what are the basal ganglia

Answer 50

large, deep cerebral nuclei

Question 51

2 functions of basal ganglia

Answer 51

1. involved in initiating movement | 2. involved in suppressing activity of muscles that would resist movement

Question 52

2 possible dysfunctions of basal ganglia

Answer 52

1. poverty of movement | 2. involuntary movement

Question 53

poverty of movement

Answer 53

bradykinesia, rigidity, tremor

Question 54

example of poverty of movement

Answer 54

Parkinson's disease

Question 55

involuntary movement

Answer 55

dyskinesia

Question 56

examples of involuntary movement

Answer 56

chorea, Tourette's, hemiballismus

Question 57

bradykinesia

Answer 57

slow movement

Question 58

4 functions of the brainstem

Answer 58

1. control of respiratory and cardiovascular musculature 2. control of sleep/wake/arousal 3. control of transmission in sensory, motor, reflex, and pain pathways 4. initiation of locomotion

Question 59

which part of the brainstem is responsible for arousal

Answer 59

reticular activating system

Question 60

which part of the brainstem is responsible for initiation of locomotion

Answer 60

midbrain locomotor area

Question 61

what inhibits the RAS

Answer 61

sedatives, barbiturates, and other anaesthetics

Question 62

what activates RAS neurons

Answer 62

visual and other sensory inputs

Question 63

what results from small lesions in RAS

Answer 63

coma

Question 64

how do anesthetics work

Answer 64

by inactivating neurons in RAS

Question 65

what requires input from neurons in RAS? what type of neurons?

Answer 65

pre-optic area of hypothalamus requires input from noradrenergic neurons in RAS