Ch 10 - Motor Neurons

Question 1

Freedforward refers to

Answer 1

the anticipatory use of sensory information to prepare for movement
(like using visual info when driving)

Question 2

Feedback refers to

Answer 2

the use of sensory information during or after movement to make corrections either to ongoing movement or to future movements (propioceptive and visual information)

Question 3

LMS reside in

Answer 3

brainstem and spinal cord

Question 4

Total resistance to muscle stretch is determiend by

Answer 4

active contraction, titin, and weak actin-myosin bonds

Question 5

Muscle tone is the

Answer 5

resistance to stretch in a resting muscle

Question 6

What is used clinically to assess muscle tone

Answer 6

PROM

Question 7

Normal resting muscle tone is provided by

Answer 7

titin and weak actin myosin bonds and low level tonic activation from descending motor input

Question 8

Loss of sarcomeres is a

Answer 8

structural adaptation to the shortened position so that the muscle generates optimal force at the new resting length

Question 9

If a mm is immobilized in a lengthened position it will

Answer 9

add new sarcomeres

Question 10

Cocontraction refers to

Answer 10

simultaneous contraction of antagonist muscles

Question 11

LMNs are the only neurons that convey signals to

Answer 11

extrafusal and intrafusal skeletal muscle fibers

Question 12

Two types of LMNs

Answer 12

alpha and gamma

Question 13

AMNs are MNs with

Answer 13

large cells bodies and large myelinated axons that reside in brainstem and spinal cord

Question 14

Gamma motor neurons consists of

Answer 14

medium sized myelinated axons

Question 15

Axons of AMNs project to

Answer 15

extrafusal skeletal muscle, branching into numerous terminals as they approach mm

Question 16

Axons of GMNs project to

Answer 16

intrafusal fibers in the muscle spindle

Question 17

H reflexes are

Answer 17

monosynaptic reflexes elicited by electrically stimulating a nerve

Question 18

Purpose of H reflexes

Answer 18

quantify the level of alpha motor neuron facilitation of inhibition

Question 19

Medial UMN tracts (4)

Answer 19

Reticulospinal
Medial vestibulospinal tracts
Lateral vestibulospinal tract
Medial corticospinal tract

Question 20

Reticulospinal tract

Answer 20

Facilitates bilateral LMN innervating postural and gross limb movement of mm throughout the body

Question 21

Medial vestibulospinal tracts

Answer 21

receives info about head mvmnt and position from vestibular apparatus

Question 22

Lateral vestibulospinal tract

Answer 22

responds to gravity information from vestibular apparatus

Question 23

Medial corticospinal tract

Answer 23

Has direct connection from cerebral cortex to the spinal cord

Question 24

Fractionation is

Answer 24

the ability to activate individual muscles independently of other mm (mvmnt of hands)

Question 25

Which is the most important pathway controlling goal-directed, voluntary movements

Answer 25

lateral corticospinal tract

Question 26

Origin of corticospinal tracts

Answer 26

primary motor, premotor, and supplementary motor cortex

Question 27

Signs of MN lesions

Answer 27

``` paresis, paralysis muscle atrophy involuntary mm contractions abnormal mm tone abnormal reflexes disturbances of mvmnt efficiency and speed impaired postural control ```

Question 28

Paresis is the

Answer 28

partial loss of voluntary contraction

Question 29

Muscle atrophy

Answer 29

loss of muscle bulk

Question 30

Most severe atrophy is produced by

Answer 30

denervation of skeletal muscle

Question 31

Flaccidity is the

Answer 31

lack of resistance to passive stretch

Question 32

Disorders of LMNs

Answer 32

Trauma, infection, degenerative or vascular disorders, and tumors can LMNs

Question 33

If LMN cell bodies and/or axons are destroyed then the affected muscles can undergo

Answer 33

loss of reflexes atrophy flaccid paralysis fibrillations

Question 34

UMN lesions can produce several changes in mvmnt control including

Answer 34

paresis or paralysis loss of fractionation of mvmnt abnormal reflexes velocity dependent hypertonia

Question 35

Paresis occurs in ___ lesions as a result of ___

Answer 35

UMN | inadequate facillitation of LMNs

Question 36

3 most common abnormal reflexes in those with chronic SCIs are

Answer 36

muscle stretch hyperreflexia clonus clasp-knife response

Question 37

Excessive mm contraction occurs when

Answer 37

spindles are stretched as a result of excessive firing of LMNs

Question 38

Clonus is

Answer 38

involuntary, repeating, and rhythmic muscle contractions

Question 39

Clasp-knife response occurs when

Answer 39

a paretic muscle is slowly and passively stretched and resistance drops at a specific point in the ROM

Question 40

____ __ ____ elicit the clasp knife response

Answer 40

type II afferents

Question 41

velocity dependent hypertonia limits

Answer 41

joint ROM, interferes with function, and may cause deformity

Question 42

myoplasticity is

Answer 42

adaptive changes within a muscle in response to changes in neuromuscular activity level and to prolonged positioning

Question 43

Spasticity is

Answer 43

neuromuscular overactivity secondary to UMN lesion

Question 44

What is the primary cause of stroke spasticity

Answer 44

brainstem UMN overactivity

Question 45

Measuring hypertonia

Answer 45

EMG | Ashworth scale

Question 46

Spastic cerebral palsy

Answer 46

abnormal supraspinal influences, failure of normal neuronal selection, and consequent aberrant muscle development lead to movement dysfunction

Question 47

Complete spinal cord injury

Answer 47

all descending neuronal control is lost below the level of the lesion

Question 48

Incomplete spinal cord injury

Answer 48

function of some ascending and/or descending fibers is preserved within the spinal cord

Question 49

Primary impairment with spastic cerebral palsy

Answer 49

paresis of agonist postural muscles

Question 50

Continuous prolonged immobilization of skeletal mm results in

Answer 50

contracture from loss of sarcomeres

Question 51

purpose of alpha gamma coactivation

Answer 51

maintain mm spindle sensitivity when extrafusal mm fibers contract

Question 52

Phasic stretch reflex AKA

Answer 52

myotatic reflex muscle stretch reflex deep tendon reflex

Question 53

reciprocal inhibition produces inhibition of the alpha motor neuron to what

Answer 53

antagonist muscle

Question 54

What contributes to spinal control of walking

Answer 54

afferent inpur interneuorns reciprocal signals crossing dorsal columb

Question 55

if LMN to mm is destroyed what sign

Answer 55

loss of reflexes and atrophy

Question 56

abnormal cutaneous reflexes that occur after an UMN lesion include what

Answer 56

Babinski | muscle spasm

Question 57

What limits movement in those who had stroke

Answer 57

paresis (dec agonist) cant fractionate abnormal timing of mm activation

Question 58

Clonus is characterized by what

Answer 58

involuntary, repetitive, and rhythmic mm contractions in response to mm stretch

Question 59

Decorticate rigidity occurs with what

Answer 59

lesions of superior midbrain