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Physiology Exam VI > Spinal Mechanisms of Motor Control > Flashcards

Spinal Mechanisms of Motor Control Flashcards

1
Q

sensory receptor

A

trasduces physical stimuli into neural signal

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2
Q

sensory input

A

afferent to CNS

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3
Q

phasic stretch reflex

A

very brief stretch usually elicited by tapping on a tendon

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4
Q

tonic stretch reflex

A

longer lasting stretch casued by stretching a muscle and holding it at its new longer legth

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5
Q

what is the fasters refelx

A

monosynaptic stretch reflex

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6
Q

where is muscle spindle

A

parallel to extrafusal muscle fibers

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7
Q

what are the intrafusal muscle fibers

A

dynamic nuclear bag
static nuclear bag
nuclear chain

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8
Q

what is the pirmary ending of sensory innervation of muscle spindle

A

group Ia fiber

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9
Q

Group Ia fier

A

usually innervates all intrafusal fibers in a muscle spindle

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10
Q

what is firing pattern of group Ia afferent related to

A

how fast the muscle length is changing and the current length of muscle

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11
Q

what is the seoncdary ending of sensory innervation of muscle spindle

A

group II fiber

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12
Q

what does firing rate of Group II fiber tell you

A

muscle length but NOT how fast muscle length is changing

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13
Q

gamma efferent fibers

A

provide fusimotor drive to muscle spindles

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14
Q

skeletofusimotor fibers

A

innervate both extrafusal and intrafusal fibers (sometimes called beta innervation)

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15
Q

muscle spindle function

A

sensory input for stretch reflexes
sensory input to cerebullum
output related to cerebral cortex for conscious proprioception

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16
Q

what is phasic stretch reflex eleicited by

A

primary ending of muscle spindle

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17
Q

what does group Ia fiber from muscle spindle synapse directly one

A

alpha motor neuron of its muscle

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18
Q

what does tonic stretch reflex depend on

A

primary and secondary endings

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19
Q

function of tonic stretch reflex

A

measure muscle tone

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20
Q

who would have exaggerated tonic stretch reflex

A

parkinsons

21
Q

co-contraction

A

simultaneous activation of agonist and antagonists at a joint

22
Q

when do we use co=contraction

A

first learning skilled movements

23
Q

inappropriate coactivation conributes to motor control problems found in children with what

A

cerebral pasly

24
Q

gain of stretch reflex

A

how large a response you get or a stretch of a certain amount

25
Q

what is gain of stretch reflex depend on

A

level of acitivty in gamma motor neurons

background inhibition/excitation of alpha motor neurons

26
Q

how is stretch reflex modified by

A

presynpathic inhibition of Ia afferent onto motor neurons

27
Q

what is GTO innervated by

A

single group Ib fiber

28
Q

GTO info goes to what

A

spinal cord
cerebellum
cerebral cortex

29
Q

what can GTO reflex cause

A

disynaptic inhibitory reflex, causes inhibition of GTO’s muscle and exitation of its antagonist

30
Q

what is the result of increase tenson on muscle

A

increases firing in Ib fiber
Ib fiber synpases on Ib inhibitory interneuron which inhibits alpha motoneuron of homonymous muscle
muscle is inhibited

31
Q

what else does Ib inhibitory neurons releve input from

A

cutaneous receptor, joint receptor, muscle spindle, descending apthway

32
Q

what do flexion flex afferents include

A

group II muscle spindle afferent

group III and group IV muscle afferents and skin afferents

33
Q

what do renshaw cells produce

A

recurrent inhibitor in alpha motor neurons of agonist muscle

34
Q

functions of renshaw cells

A

inhibit synergistic alpha motor neurons and gamma motor enurons to homonynmous and synergistic muscles
inhbit Ia inhibitory interneurons to agtagonist muscle

35
Q

disinhibition

A

inhibiting a inhibitor

36
Q

what are the 2 phases of maintained muscle stretch

A

dynamic phase and static or steady phase

37
Q

static/steady phase

A

muscle has stabilized at new length

38
Q

Ia fibers

A

big, fast myelinated

39
Q

II fibers

A

less bi and fast compared to Ia

40
Q

where are Ia fibers going

A

every intrafusal muscle fibers

41
Q

what do II fibers carry

A

static information

42
Q

what sets the sensitivity of the muscle spindle

A

gamma celsl

43
Q

is Ia fiber firing during muscle contraction

A

no

44
Q

how does co-contraction affect joint

A

stiffens

45
Q

where are GTOs found

A

between muscle and tendon, in series with muscle

46
Q

what else is Ib reflex known as

A

inverse myotactic reflex

47
Q

glycine

A

most common inhibitory neurotransmitter in spinal cord

48
Q

how are renshaw cells involved in spasticity

A

if spaciticy results from cutting descending tracts we are having disordered regulation of renshaw cells

Physiology Exam VI (18 decks)

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