Ch 9

Front 1

what is feedforward

Back 1

the anticipatory use of sensory info to prepare for movement

Front 2

feedback

Back 2

provide info during and after movement

Front 3

where is a decision first made

Back 3

in the anterior part of the frontal lobe

Front 4

after a decision is made in the anterior part of the frontal lobe what happens next

Back 4

motor planning areas in the frontal lobe are activated followed by control circuits

Front 5

what regulates activity in descending pathways

Back 5

motor control circuits: cerebellum and basal ganglia

Front 6

after a decision is made in the frontal lobe and motor planning areas and control circuits are activated what happens

Back 6

upper motor neuron tracts ( descending motor pathways) deliver signals to the spinal interneurons and LMN's

Front 7

after signal reaches the spinal interneurons and LMN's what happens

Back 7

the LMN's deliver the signal directly to skeletal muscle, eliciting contraction

Front 8

in the spinal cord, what determines the information conveyed by the LMNs to the muscles

Back 8

interactions among neurons

Front 9

what are the classifications of UMN tracts

Back 9

- postural/gross movement tracts

- fine movement tracts

Front 10

what do postural/gross movement tracts control

Back 10

automatic skeletal muscle activity

Front 11

what do fine movement tracts control

Back 11

fractionated movements of the limbs and face

Front 12

the control circuits adjust activity in the descending tracts resulting in _______ or _______

Back 12

excitation or inhibition of motor neurons

Front 13

what is the sarcolemma

Back 13

the membrane of a muscle cell

Front 14

what are t tubles

Back 14

projections on the sarcolemma which extend into muscle

Front 15

what is the sarcoplasmic reticulum and where is it located

Back 15

- a series of storage sacs for Ca ions

- adjacent to T tubules

Front 16

what causes the membrane on a muscle cell to depolarize and what happens following this depolarization

Back 16

- ACh from a LMN binds with receptors on the sarcolemma

- this induces depolarization of T tubules

Front 17

once sarcolemma and T tubules have depolarized, what does this change in electrical potential elicit and what does this cause

Back 17

the release of Ca ions from sarcoplasmic reticulum. These ions then bind to receptors inside muscle cells , initiating contraction

Front 18

what do individual muscle fibers consist of

Back 18

myofibrils arranged in parallel to the long axis of the muscle fiber

Front 19

what do myofibrils consist of

Back 19

proteins arranged in sarcomeres

Front 20

what are the functional units of muscle

Back 20

sarcomeres

Front 21

sarcomeres are composed of two types of proteins _______ and _______

Back 21

structural and contractile

Front 22

what are the contractile proteins in a sarcomere (myofilaments)

Back 22

actin, myosin, troponin, tropomyosin

Front 23

what are the structural proteins of a sarcomere (myofilaments)

Back 23

Z line, M line, tintin

Front 24

what is the Z line

Back 24

fibrous structure at each end of a sarcomere

Front 25

what is the M line

Back 25

it anchors the fibers in the center of the sarcomere

Front 26

what is tintin

Back 26

large elastic protein, connects Z line with the M line

Front 27

what is the function of tintin

Back 27

it maintains the position of myosin relative to actin and prevents the sarcomere from being pulled apart

Front 28

myosin filaments have specialized projections called ___________ ending in _________

Back 28

- cross bridges

- myosin heads

Front 29

myosin head are capable of

Back 29

binding with active sites on actin

Front 30

a thin protein attached to the Z line

Back 30

actin

Front 31

a thick filament attached to the M line

Back 31

myosin

Front 32

muscle contraction is produced when

Back 32

actin slides relative to myosin

Front 33

what initiates the sliding of actin relative to myosin

Back 33

when Ca binds to troponin, causing a change to troponin. This change induces movement of the tropomyosin to uncover active sites on actin , allowing myosin heads to attach to these exposed active sites

** ca binds/changes troponin = movement of tropomyosin= uncovers active actin sites/myosin binds to

Front 34

the amount of tension generated by contracting muscle depends on

Back 34

length of the sarcomeres

Front 35

what determines the total resistance to muscle stretch

Back 35

active contraction, tintin, weak actin myosin bonds

Front 36

what is the definition of muscle tone

Back 36

the resistance to stretch in resting muscle

Front 37

clinically, what is used to asses muscle tone

Back 37

passive range of motion

Front 38

normal resting muscle tone is provided by

Back 38

tintin and weak actin myosin bonds

Front 39

weak actin myosin bonds are formed when

Back 39

when myosin attaches to actin but myosin heads do not swivel so there is not power stroke

Front 40

force generated by muscles is determined by muscle

Back 40

stiffness

Front 41

what is stiffness technically defined as

Back 41

change in force per change in length

Front 42

what determines total stillness of a muscle

Back 42

active, intrinsic, and passive factors

Front 43

what is active stiffness generated by

Back 43

neural activity ( UMN firing and reflexes)

Front 44

when innervated mm is immobilized in a shortened position what happens

Back 44

structural adaptation

- sarcomeres are lost

Front 45

stiffness is

Back 45

resistance to stress

Front 46

tone is

Back 46

amount of tension (stiffness) in resting muscle

Front 47

what makes up the motor unit

Back 47

the alpha motor neuron and all the muscle fibers it innervates

Front 48

the activity of the motor unit depends on the convergence of information from these three areas:

Back 48

peripheral sensory afferents

interneurons

descending pathways

Front 49

what is the function of slow twitch mm fibers

Back 49

majority of postural and slowly contracting muscles

Front 50

what is alpha gamma coactivation

Back 50

the simultaneous functioning of alpha and gamma systems which occurs during most movements

gamma maintains stretch on central region of mm spindle intrafusal fibers when the muscle actively contracts

Front 51

what do spinal region reflexes require

Back 51

1. sensory receptors

2. primary afferents

3. connections between primary afferents and LMN

4. effectors (muscles or glands)

Front 52

what are the diff. names of the phasic stretch reflex

Back 52

1. myotatic reflex

2. muscle stretch reflex

3. deep tendon reflex

Front 53

describe the phasic stretch reflexs

Back 53

1. Ia afferents stimulated by quick stretch

2. transmit AP to spinal cord

3. release neurotransmitter at synapses with alpha motor neuron

4. alpha motor neuron depolarizes

5. Ap propagated o neuromuscular junction

6. Ach released, binds with mm receptors, fibers contract

Front 54

describe the Golgi tendon organ stretch reflex

Back 54

1. Ib afferents

2. stimulate interneurons that INHIBIT alpha motorneuron to same muscle

3. results in AUTOGENIC INHIBITION

4. may also inhibit synergistic musle

Front 55

what is the purpose of the GTO reflex

Back 55

- adjusts the mm activity in concert w/ info from muscle spindle and descending control

- in extreme contraction, prevents muscle from exerting enough force to tear the tendon, can fail if force build up is very rapid

Front 56

tonic stretch reflex is _______synaptic

Back 56

multisynaptic

Front 57

phasic stretch reflex is _____synaptic

Back 57

monosynaptic

Front 58

what is a normal muscle synergy

Back 58

elbow and wrist flexion combined with forearm supination to get food to mouth when eating

Front 59

what is the difference between the medial and lateral activation system of descending pathways

Back 59

- medial synapse medially and innervate postural and girdle muscles

- lateral synapse laterally and innervate distal muscles used for fine movement

Front 60

what are the pathways in the medial activation system

Back 60

1. tectospinal

2. medial reticulospinal

3. medial vestibulospinal

4. lateral vestibulospinal

Front 61

where do the pathways in the medial activation system come from

Back 61

1. tectospinal from tectum ( posterior midbrain)

2. medial reticulospinal from medial reticular formation

3. med & lat. vestibulospinal from vestibular nuclei

Front 62

what does the term fractionation of movement mean

Back 62

ability to activate individual muscles independently of other muscles

Front 63

where do corticospinal fibers come from

Back 63

1. primary motor cortex

2. lateral premotor area

3. supplementary motor area

Front 64

what is the function of the lateral premotor area

Back 64

preparing to move

- produces muscle activity that spans several joints

Front 65

what is the function of the supplementary motor area

Back 65

preparing to move

- active prior to bimanual and sequential movements

Front 66

what is the function of the lateral corticospinal tract

Back 66

- controls fine distal movements

Front 67

what is the function of the rubrospinal tract

Back 67

primarily innervates upper limb flexors

Front 68

what is the purpose of the non specific activating pathways

Back 68

enhance activity of interneurons and motor neurons in spinal cord

- motor effects due to release of neuromodulators

- general effects not related to specific movements

- may contribute to motor performance with varying levels of motivation

Front 69

what are the signs of upper motor neuron lesion

Back 69

1. paresis

2. loss of fractionation of movement

3. abnormal reflexes

4. muscle hyperstiffness

5. cocontraction ( spastic CP)

6. abnormal muscle synergies ( post stroke)

Front 70

what are the signs of lower motor neuron lesion

Back 70

1. loss of reflexes

2. atrophy

3. flaccid paralysis

4. fibrillations

Front 71

what is the difference between paralysis and paresis

Back 71

paralysis is complete loss of voluntary contraction

paresis is partial loss of voluntary contraction

Front 72

what is the difference between disuse atrophy and neurogenic atrophy

Back 72

disuse- due to lack of use

neurogenic- due to damage of nervous system

Front 73

what kind of atrophy do you see with upper motor neuron lesion

Back 73

disuse atrophy

- skeletal muscle continues to receive stimulation, slower rate of atrophy

Front 74

what kind of atrophy do you see with lower motor neuron lesion

Back 74

neurogenic atrophy

- muscle doesn't get innervation anymore causing atrophy which is profound and happens quickly

Front 75

what are the different types of involuntary muscle contraction

Back 75

1. muscle spasm

2. cramps

3. fasciculations

4. fibrillations

5. abnormal movements

Front 76

define muscle spasm

Back 76

sudden involuntary contraction

Front 77

define crams

Back 77

severe and painful muscle spasms

Front 78

define fibrillations

Back 78

brief contractions of single muscle fibers, not visible

Front 79

define fasciculations

Back 79

quick twitches of muscle fibers of single motor unit, visible under skin

Front 80

what are abnormal movements due to

Back 80

basal ganglia disorders

Front 81

what is flaccidity

Back 81

hypotonia

- abnormally low resistance to passive stretch

Front 82

what are the causes of flaccidity

Back 82

- cerebellar disorders

- lower motor neuron lesions

- temporarily following UMN lesion

Front 83

what is hypertonia and what causes it

Back 83

abnormally strong resistance to passive stretch

- chronic UMN lesions

- some BG disorders

Front 84

what is the difference between spastic hypertonia and rigidity

Back 84

with spastic the amount of resistance to passive movement depends on velocity of movement where as rigidity resistance remains constant it is velocity independent

Front 85

what is the difference between decerebrate and decorticate rigidity

Back 85

decerebrate occurs following midbrain lesions

- rigid extension of limbs and trunk, IR of UE, PF

decorticate occurs following lesions superior to midbrain

- UE are flexed, LE extended

Front 86

what happens when descending motor commands are interrupted

Back 86

LMN becomes temporarily inactive

no stretch reflexes, muscles hypotonic

After recovery interneurons and LMN usually resume activity but their activity no longer modulated of abnormally modulated by UMNN

In months following UMN injury tone inc. d/t changes w/in mm = ^ resistance to stretch

Front 87

what is one common abnormal cutaneous reflex? what does it look like?

Back 87

babinskis sign

extension of big toe and fanning out of other toes, CST tract

Front 88

what is clonus

Back 88

involuntary, repeating, rhythmic contractions caused by mm stretch, cutaneous and noxious stimuli and attempts at voluntary movement can induce clonus

Front 89

what is the clasp knife response? what kind of disorder do you find it in?

Back 89

when paretic muscle is slowly and passively stretched, resistance drops at a specific point in the range of motion

- type 2 afferents including some joint, cutaneous, subcutaneous, touch, and pressure receptors elicit the response

Front 90

what is the cause of muscle hyperstiffness post stroke?

Back 90

1. loss of sarcomeres

2. inc. weak actin myosin bonds

3. atrophy of type 2 muscle fibers

Front 91

how does muscle hyperstiffness change normal movement

Back 91

1. abnormal movement

2. delayed initiation of movement

3. slowed rate of force development

4. prolonged mm contraction time

5. disrupted timing of activation of antagonists relative to agonist

Front 92

what is the modified ashforth scale? and how is it used?

Back 92

subjective assessment of the resistance to passive stretch

Front 93

what tract is most damaged from stroke?

Back 93

corticospinal tract

Front 94

what is the most common site of stroke

Back 94

middle cerebral artery

Front 95

what does damage to the corticospinal tract cause

Back 95

abnormal motor control and over activity of antigravity mm

- abnormal mm activation: extension from med. reticulospinal and vestibulospinal tract left relatively unopposed

- rubrospinal tract still intact, = UE flex

Front 96

besides movement consequences what other consequences of stroke are there

Back 96

emotional lability

Front 97

what are the interventions for stroke that are best supported by the research

Back 97

- constraint induced movement

- movements against resistance

- partial body weight support during gait train.