Physiology - Central Nervous System Motor Control : Spinal Reflexes

Question 1

where does the stretch reflex originate

a.dorsal horn
b.golgi tendon organ
c. muscle spindle

Answer 1

c. muscle spindle

Question 2

where does the inverse stretch reflex originate

a.dorsal horn
b.golgi tendon organ
c. muscle spindle

Answer 2

b.golgi tendon organ

Question 3

the stretch reflex originates from the muscle spindle and controls and signals muscle

a.length
b.force

Answer 3

a.length

Question 4

the inverse stretch reflex originates from the golgi tendon organ and controls and signals muscle

a.length
b.force

Answer 4

b.force

Question 5

the muscle spindle is arranged in parallel with which fibres

a.intrafusal
b.extrafusal

Answer 5

b.extrafusal

Question 6

which fibres make up the muscle spindle
a.intrafusal
b.extrafusal

Answer 6

a.intrafusal

Question 7

intrafusal fibres of the muscle spindle have ………… ends

a.contractile
b.non contractile

Answer 7

a.contractile

Question 8

intrafusal fibres of the muscle spindle have ………… centres

a.contractile
b.non contractile

Answer 8

b.non contractile

Question 9

afferent fibres from the spindles centres are …

a.small and myelinated
b.small and unmyelinated
c.large and myelinated
d.large and unmyelinated

Answer 9

c.large and myelinated

classed as type Ia and II

Question 10

the contractile ends of muscle spindles are innervated by …………………….. nerves

a.small and myelinated
b.small and unmyelinated
c.large and myelinated
d.large and unmyelinated

Answer 10

a.small and myelinated

y efferents

Question 11

which type of nerve innervates the dynamic nuclear bag fibres in the spindle

a. Ia
b.II
c.Y

Answer 11

a. Ia

signal rapid change in muscle length, firing maximally when the muscle is rapidly stretched (dynamic response)

Question 12

Ia fibres in the dynamic nuclear bag signal ………. changes in muscle length

a.slow
b.rapid

Answer 12

b.rapid

Question 13

static nuclear bag fibres are innervated by which fibres

a.Ia
b.II
c.Y
d.Ia and II
e.Ia and Y

Answer 13

d.Ia and II

Question 14

which of these afferents conducts the fastest

a.Ia
b.II
c.Y

Answer 14

a.Ia

Question 15

which of these fibres signals muscle length itself

a.dynamic nuclear bag
b.static nuclear bag
c.nuclear chain

Answer 15

b.static nuclear bag

Question 16

which fibres provide the dynamic response

a.dynamic nuclear bag fibres
b.static nuclear bag fibres
c.nuclear chain fibres
d.dynamic and static nuclear bag fibres
e.static nuclear bag fibres and nuclear chain fibres

Answer 16

a.dynamic nuclear bag fibres

Question 17

what do nuclear chain fibres play a role in signalling

a.change in muscle length
b.absolute muscle length

Answer 17

b.absolute muscle length

Question 18

which fibres together give the static response of the muscle spindle

a.dynamic nuclear bag fibres
b.static nuclear bag fibres
c.nuclear chain fibres
d.dynamic and static nuclear bag fibres
e.static nuclear bag fibres and nuclear chain fibres

Answer 18

e.static nuclear bag fibres and nuclear chain fibres

Question 19

when the main a nerve of the muscle activates the extrafusal fibres that contract the muscle the y fibres fire and …………. the spindle

a.shorten
b.lengthen

Answer 19

a.shorten

Question 20

the stretch reflex

Answer 20

afferents from the bag and chain fibres directly innervate muscle being stretched so it contracts against the stretch, smoothing movement and rapid change in muscle length

Question 21

recipricol innervation of the antagonistic muscle to the one being stretched via an ……………. interneuron to the spinal cord means that it is inhibited too aiding the damping effect of rapid muscle length change

a.excitatory
b.inhibitory

Answer 21

b.inhibitory

Question 22

a net of nerve endings embedded within the fascicles of a tendon

a.muscle spindle
b.golgi tendon organ

Answer 22

b.golgi tendon organ

Question 23

the golgi tendon origin is in ………. with the muscle

a.parallel
b.series

Answer 23

b.series

Question 24

what do golgi tendon organs fire more in response to

a.muscle stretch
b.muscle force

Answer 24

b.muscle force

Question 25

when too much force is generated by a muscle what is activated a.muscle spindle b.golgi tendon organ

Answer 25

b.golgi tendon organ

Question 26

how does the GTO reduce the activity of motor neurons a.excitatory interneuron b.inhibitory interneuron

Answer 26

b.inhibitory interneuron

Question 27

the reflex regulated by what allows for regulation of force eg when holding an object with a constant grip a. muscle spindle b.golgi tendon organ

Answer 27

b.golgi tendon organ

Question 28

clonus (exagerrated tremor in response to very minor stimuli) happens in which lesions a.upper motor neuron b.lower motor neuron

Answer 28

a.upper motor neuron eg stroke, amytrophic lateral sclerosis, spinal cord lesions and hepatic encephalopathy

Question 29

abscence of descending inhibitory input to which fibres leads to clonus a.Ia b.II c.Y

Answer 29

c.Y

Question 30

the clasp knife effect

Answer 30

over excitable stretch reflexes resistance to initial passive flexion of elbow then after certain point sudden collapse of resistance and quick flexion like putting the blade back in a swiss army knife

Question 31

in the clasp knife effect

Question 32

inverse stretch reflex

Answer 32

mediated by golgi tendon organ when muscle stretched too much they cause muscle relaxation via inhibitory interneuron

Question 33

stretch reflex

Answer 33

mediated by muscle spindle when muscle stretched too much spindle contracts and muscle contracts to prevent rapid change in length

Question 34

in the clasp knife effect in the triceps the .............. reflex quickly switches to the ................... a.stretch, inverse stretch b.inverse stretch, stretch

Answer 34

a.stretch, inverse stretch stretch reflex initially as doctor tries to stretch triceps and spindle contracts against this to stop sudden change in muscle length arm resists passive flexion inverse stretch after certain point as triceps has contracted too much force and GTO causes triceps to relax and arm flexes quickly

Question 35

the clasp knife effect indicates a.UMN lesion b.LMN lesion

Answer 35

a.UMN lesion

Question 36

in which reflex does stimulation of of a flexor muscle inhibit the antagonistic extensor muscle on the same limb eg removing hand from painful stimulus a.stretch b.reverse stretch c.crossed extensor d.positive supporting e.flexor

Answer 36

e.flexor

Question 37

in which reflex do extensors contract and flexors are inhibited in the opposing limb a.stretch b.reverse stretch c.crossed extensor d.positive supporting e.flexor

Answer 37

c.crossed extensor

Question 38

the leg extending to push down on a finger touching the sole of the foot in a baby describes which reflex a.stretch b.reverse stretch c.crossed extensor d.positive supporting e.flexor

Answer 38

d.positive supporting

Question 39

in UMN lesions what happens to the crossed extensor, flexor and positive supporting reflex a.masked b.un masked

Answer 39

b.un masked no longer overidden by supraspinal reflexes