Physiology - Central Nervous System Motor Control : Spinal Reflexes Flashcards
where does the stretch reflex originate
a.dorsal horn
b.golgi tendon organ
c. muscle spindle
c. muscle spindle
where does the inverse stretch reflex originate
a.dorsal horn
b.golgi tendon organ
c. muscle spindle
b.golgi tendon organ
the stretch reflex originates from the muscle spindle and controls and signals muscle
a.length
b.force
a.length
the inverse stretch reflex originates from the golgi tendon organ and controls and signals muscle
a.length
b.force
b.force
the muscle spindle is arranged in parallel with which fibres
a.intrafusal
b.extrafusal
b.extrafusal
which fibres make up the muscle spindle
a.intrafusal
b.extrafusal
a.intrafusal
intrafusal fibres of the muscle spindle have ………… ends
a.contractile
b.non contractile
a.contractile
intrafusal fibres of the muscle spindle have ………… centres
a.contractile
b.non contractile
b.non contractile
afferent fibres from the spindles centres are …
a.small and myelinated
b.small and unmyelinated
c.large and myelinated
d.large and unmyelinated
c.large and myelinated
classed as type Ia and II
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
a.small and myelinated
y efferents
which type of nerve innervates the dynamic nuclear bag fibres in the spindle
a. Ia
b.II
c.Y
a. Ia
signal rapid change in muscle length, firing maximally when the muscle is rapidly stretched (dynamic response)
Ia fibres in the dynamic nuclear bag signal ………. changes in muscle length
a.slow
b.rapid
b.rapid
static nuclear bag fibres are innervated by which fibres
a.Ia
b.II
c.Y
d.Ia and II
e.Ia and Y
d.Ia and II
which of these afferents conducts the fastest
a.Ia
b.II
c.Y
a.Ia
which of these fibres signals muscle length itself
a.dynamic nuclear bag
b.static nuclear bag
c.nuclear chain
b.static nuclear bag
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
a.dynamic nuclear bag fibres
what do nuclear chain fibres play a role in signalling
a.change in muscle length
b.absolute muscle length
b.absolute muscle length
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
e.static nuclear bag fibres and nuclear chain fibres
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
a.shorten
the stretch reflex
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
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
b.inhibitory
a net of nerve endings embedded within the fascicles of a tendon
a.muscle spindle
b.golgi tendon organ
b.golgi tendon organ
the golgi tendon origin is in ………. with the muscle
a.parallel
b.series
b.series
what do golgi tendon organs fire more in response to
a.muscle stretch
b.muscle force
b.muscle force
when too much force is generated by a muscle what is activated
a.muscle spindle
b.golgi tendon organ
b.golgi tendon organ
how does the GTO reduce the activity of motor neurons
a.excitatory interneuron
b.inhibitory interneuron
b.inhibitory interneuron
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
b.golgi tendon organ
clonus (exagerrated tremor in response to very minor stimuli) happens in which lesions
a.upper motor neuron
b.lower motor neuron
a.upper motor neuron
eg stroke, amytrophic lateral sclerosis, spinal cord lesions and hepatic encephalopathy
abscence of descending inhibitory input to which fibres leads to clonus
a.Ia
b.II
c.Y
c.Y
the clasp knife effect
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
in the clasp knife effect
inverse stretch reflex
mediated by golgi tendon organ
when muscle stretched too much
they cause muscle relaxation via inhibitory interneuron
stretch reflex
mediated by muscle spindle
when muscle stretched too much
spindle contracts
and muscle contracts to prevent rapid change in length
in the clasp knife effect in the triceps the ………….. reflex quickly switches to the ……………….
a.stretch, inverse stretch
b.inverse stretch, stretch
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
the clasp knife effect indicates
a.UMN lesion
b.LMN lesion
a.UMN lesion
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
e.flexor
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
c.crossed extensor
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
d.positive supporting
in UMN lesions what happens to the crossed extensor, flexor and positive supporting reflex
a.masked
b.un masked
b.un masked
no longer overidden by supraspinal reflexes
