Cognitive/motor 2

Question 1

describe motor behaviour

Answer 1

things need cns to move
Purposeful or goal oriented

Question 2

describe 2 types of motor behaviour

Answer 2

voluntary
reflexive

Question 3

what do al motor movements require and why

Answer 3

2 muscles
agonist muscle contracts and antagonist relaxes
to make muscle contract = activate motor neurons
to make muscle relax = inhibit motor neurons

Question 4

describe extension

Answer 4

agonist = extensor muscle contracts
antagonist = flexor muscle relaxes
increases angle around joint

Question 5

describe flexion

Answer 5

agonist = flexor muscle contracts
antagonist = extensor muscle relaxes
decreases angle around joint

Question 6

describe reciprocal innervation of muscles

Answer 6

coordinated flexor and extensor muscle activation and relaxation
limb position maintained by balance of flexor and extensor muscle tension

Question 7

describe motor neurons

Answer 7

only excitatory - ach
alpha = innervate skeletal muscle extrafusal (makes big muscles contract)
gamma = innervates muscle spindle - intrafusal (part of proprioceptive feedback)
cell bodies in ventral horn of spinal cord - spinal nerves or brainstem (cranial nerves)
receives inputs mostly from interneurons

Question 8

describe spinal afferent pathway

Answer 8

sensory afferent - dorsal root ganglion
synapses both on interneuron and ascends dorsal columns to brain

Question 9

descrive motor efferent patway

Answer 9

descending motor commands = comes from brain and innervate interneurons, voluntary input
Interneurons = integrate info from many things, like sensory info and motor commands and then activates other circuitry and sends axons and forms motor efferent

Question 10

name and describe spinal interneurons

Answer 10

descending pathway
other spinal levels = voluntary movements
muscle receptor from antagonistic muscle = length monitoring
spinal interneuron
tendon receptor = tension monitoring, force of muscles
skin receptor = pain, driven by nociceptors
joint receptor = proprioceptive feedback

Question 11

name 3 spinal reflexes

Answer 11

withdrawal
stretch
inverse stretch

Question 12

describe withdrawal reflex

Answer 12

protects limb from injury
involuntary - happens at level of spinal cord

Question 13

can most spinal reflexes be overriden

Answer 13

yesss
like if pain but its important to withdraw limb

Question 14

describe flexion withdrawal reflex - polysynaptic

Answer 14

polysynaptic= more than one synapse between sensory input and motor response
activate nociceptors = aps up leg and enters dorsal horn and branches of axons activate interneurons, synapses on 2nd order neurons
innervates motor neurons in ventral horn of gray matter
Causes inhibition of motor neurons innervating ipsilateral extensor
excitation of motor neurons innervating ipsilateral flexor (contracts)
causes withdrawal

Question 15

describe flexion withdrawal reflex - cross extensor reflex

Answer 15

when withdrawal = weight must shift to other leg
motor afferents = cross midline to anterolateral and do opposite
excitation of motor neurons innervating contralateral extensor
Inhibition of motor neurons innervating contralateral flexor

Question 16

what does magnitude of withdrawal reflex depend on

Answer 16

magnitude of stimulus
more painful = bigger withdrawal

Question 17

describe irradiation

Answer 17

A>b>c = pain input bigger for a and less as go to c
recruitment of interneurons drives increased withdrawal with increased pain, more aps = more drives motor neurons
Increase in rate and magnitude of withdrawal response with increased stimulus strength

Question 18

describe afterdischarge

Answer 18

Response maintained after stimulus termination
feedback loops in spinal cord
keep reflex going
ppl withdrawal = tend not to reextend

Question 19

describe polysynaptic - properties of withdrawal reflex

Answer 19

Interneurons between sensory input and motor output

Question 20

describe ipsilateral - properties of withdrawal reflex

Answer 20

Flexor muscle contraction Extensor muscle relaxation

Question 21

describe contralateral - properties of withdrawal reflex

Answer 21

Flexor muscle relaxation
Extensor muscle contraction (cross extensor reflex)

Question 22

describe stretch reflex

Answer 22

controls muscle length or involves lengthening of muscles
monosynaptic - primary
polysynaptic - secondary

Question 23

describe monosynaptic stretch reflex - knee jerk

Answer 23

little hammer stretches muscles
stretch extensor muscle - tap on tendon = pulls extensor muscle and activates stretch receptors (cell bodies in dorsal root ganglion)
goes up ipsilateral dorsal columns and tells brain muscle length is changing
also branches into spinal cord and synapses and produces motor response = excitation of motor neurons innervating ipsilateral extensor
polysynaptic = interneuron and inhibition of motor neurons innervating ipsilateral flexor = leg kicks

Question 24

what asses muscle tone

Answer 24

stretch reflex - knee jerk
ability of muscles to resist being stretched = they pull back
Patient needs to be conscious
if tone gone or too big = indication of porbelm with cns pathways coming down spinal cord

Question 25

name the 2 kinds of stretch receptors = proprioceptive receptors

Answer 25

muscle spindle
golgi tendon organ

Question 26

describe golgi tendon organ

Answer 26

located in tendons
in series = whatever force muscle generates
golgi tendon organ feels force and reports to cns - in tendons = attach muscle to bone
Measures muscle tension

Question 27

describe muscle spindle

Answer 27

in parallel with extrafusal muscle
has stretch receptor and intrafusal muscle fiber
Activated by during stretch reflex and sends ap to spinal cord
stretch receptor = in middle, located at each end of part of stretch receptor that measures muscle length
intrafusal muscle fiber= activated by gamma motor neurons, regulates stretch receptor
measures muscle length - embedded in muscle - however long muscle is when contracts or relaxes = stretch receptor follows same length
extrafusal muscle fiber - activated by alpha motor neurons = causes you to move= generate force, causes contraction of muscle and movement, sits around muscle spindle

Question 28

describe muscle spindles

Answer 28

afferents - ia and ii = 2 types of afferents come out of muscle spindles
gamma motor axons = come in and innervate both sides of intrafusal muscle fiber

Question 29

describe response of ia and ii afferents

Answer 29

Ia = primary
nuclear bag fibers = rapidly adapting indicates change in sensory input = when muscle length is changing
when stretch reflex = mediates it, only picks it up and communicates it

ii secondar
nuclear chain fibers
communicates static changes in muscle legth
non adapting slower to respond, static steady state muscle length

Question 30

describe ia primary

Answer 30

signal dynamic changes in muscle length and some static changes

Question 31

describe ii secondary

Answer 31

signal static muscle length

Question 32

what can muscle spindles do

Answer 32

lose sensitivy

Question 33

describe muscle spindle during extension

Answer 33

Muscles lengthen
feels lengthening of muscle and increases aps and tells cns muscle is longer
increase in muscle spindle afferent activity

Question 34

describe muscle spindle during voluntary flexion

Answer 34

alpha motor neuron activity muscles shorten
muscle spindle collapses = sensitivity reduced
mostly work when stretched - when contracted = does not work, gamma neurons come to rescue

Question 35

what do gamma motor neurons do

Answer 35

maintain muscle spindle sensitivity

Question 36

how does gamma motor neurons maintain muscle spindle sensitivity

Answer 36

causes intrafusal fibers contract and muscle spindle is stretched - stretches them out, maintains muscle spindle sensitivity
alpha gamma coactivation

Question 37

describe alpha gamma coactivation

Answer 37

descending pathways come down spinal cord and activate both alpha and gamma
Alpha = extrafusal muscle contraction and shortening
gamma = intrafusal muscle activation and maintains spindle sensitivity
change in length activates muscle spindle

Question 38

describe properties of stretch reflex- 3

Answer 38

Resists changes in muscle length (sets muscle tone)
Mono- and polysynaptic components
Feedback from muscle spindles

Question 39

describe properties of muscles spindles - 6

Answer 39

1) Reports muscle length.
2) In parallel with extrafusal muscle fibers (does not contribute to the force of muscle contraction).
3) Ia primary: Detects changes in muscle length and some static length (nuclear bag fibers).
4) II secondary: Detects static length (nuclear chain fibers).
5) Intrafusal fibers: Maintain muscle spindle sensitivity.
6) Alpha-gamma coactivation

Question 40

describe inverse stretch reflexes

Answer 40

controls muscle tension

Question 41

what does golgi tendon organ respond to

Answer 41

tension

Question 42

describe golgi tendon organ - for inverse stretch reflex

Answer 42

in series with muscle
passive stretch = might activate a few aps
fully contracting muscle = much force, many aps, lots of tension, active contraction of extrafusal muscle fibers
active contraction of muscle produces more tension than stretching
collagen fibers pinched inside golgi tendon organ = tough fibers, in between = free nerve endings = pinch free nerve endings = activate mechanically gated ion channels

Question 43

describe inverse stretch reflex pathway

Answer 43

Activation of golgi tendon organ via 1b afferents, goes up ipsilateral dorsal columns
increased tension in extensor muscle = increased afferent activity from golgi tendon organ = branches in gray matter and interneurons
Inhibition of motor neurons innervating ipsilateral extensor - both alpha and gamma
excitation of motor neurons innervating ipsilateral flexor - antagonist muscle

Question 44

describe properties of golgi tendon organ

Answer 44

1) Reports muscle tension.
2) In series with extrafusal muscle fibers
3) Ib afferents
4) Underlies inverse stretch reflex (polysynaptic)