Spinal Mechanisms of Motor Control

Question 1

sensory receptor

Answer 1

trasduces physical stimuli into neural signal

Question 2

sensory input

Answer 2

afferent to CNS

Question 3

phasic stretch reflex

Answer 3

very brief stretch usually elicited by tapping on a tendon

Question 4

tonic stretch reflex

Answer 4

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

Question 5

what is the fasters refelx

Answer 5

monosynaptic stretch reflex

Question 6

where is muscle spindle

Answer 6

parallel to extrafusal muscle fibers

Question 7

what are the intrafusal muscle fibers

Answer 7

dynamic nuclear bag
static nuclear bag
nuclear chain

Question 8

what is the pirmary ending of sensory innervation of muscle spindle

Answer 8

group Ia fiber

Question 9

Group Ia fier

Answer 9

usually innervates all intrafusal fibers in a muscle spindle

Question 10

what is firing pattern of group Ia afferent related to

Answer 10

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

Question 11

what is the seoncdary ending of sensory innervation of muscle spindle

Answer 11

group II fiber

Question 12

what does firing rate of Group II fiber tell you

Answer 12

muscle length but NOT how fast muscle length is changing

Question 13

gamma efferent fibers

Answer 13

provide fusimotor drive to muscle spindles

Question 14

skeletofusimotor fibers

Answer 14

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

Question 15

muscle spindle function

Answer 15

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

Question 16

what is phasic stretch reflex eleicited by

Answer 16

primary ending of muscle spindle

Question 17

what does group Ia fiber from muscle spindle synapse directly one

Answer 17

alpha motor neuron of its muscle

Question 18

what does tonic stretch reflex depend on

Answer 18

primary and secondary endings

Question 19

function of tonic stretch reflex

Answer 19

measure muscle tone

Question 20

who would have exaggerated tonic stretch reflex

Answer 20

parkinsons

Question 21

co-contraction

Answer 21

simultaneous activation of agonist and antagonists at a joint

Question 22

when do we use co=contraction

Answer 22

first learning skilled movements

Question 23

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

Answer 23

cerebral pasly

Question 24

gain of stretch reflex

Answer 24

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

Question 25

what is gain of stretch reflex depend on

Answer 25

level of acitivty in gamma motor neurons | background inhibition/excitation of alpha motor neurons

Question 26

how is stretch reflex modified by

Answer 26

presynpathic inhibition of Ia afferent onto motor neurons

Question 27

what is GTO innervated by

Answer 27

single group Ib fiber

Question 28

GTO info goes to what

Answer 28

spinal cord cerebellum cerebral cortex

Question 29

what can GTO reflex cause

Answer 29

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

Question 30

what is the result of increase tenson on muscle

Answer 30

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

Question 31

what else does Ib inhibitory neurons releve input from

Answer 31

cutaneous receptor, joint receptor, muscle spindle, descending apthway

Question 32

what do flexion flex afferents include

Answer 32

group II muscle spindle afferent | group III and group IV muscle afferents and skin afferents

Question 33

what do renshaw cells produce

Answer 33

recurrent inhibitor in alpha motor neurons of agonist muscle

Question 34

functions of renshaw cells

Answer 34

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

Question 35

disinhibition

Answer 35

inhibiting a inhibitor

Question 36

what are the 2 phases of maintained muscle stretch

Answer 36

dynamic phase and static or steady phase

Question 37

static/steady phase

Answer 37

muscle has stabilized at new length

Question 38

Ia fibers

Answer 38

big, fast myelinated

Question 39

II fibers

Answer 39

less bi and fast compared to Ia

Question 40

where are Ia fibers going

Answer 40

every intrafusal muscle fibers

Question 41

what do II fibers carry

Answer 41

static information

Question 42

what sets the sensitivity of the muscle spindle

Answer 42

gamma celsl

Question 43

is Ia fiber firing during muscle contraction

Answer 43

no

Question 44

how does co-contraction affect joint

Answer 44

stiffens

Question 45

where are GTOs found

Answer 45

between muscle and tendon, in series with muscle

Question 46

what else is Ib reflex known as

Answer 46

inverse myotactic reflex

Question 47

glycine

Answer 47

most common inhibitory neurotransmitter in spinal cord

Question 48

how are renshaw cells involved in spasticity

Answer 48

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