exam 2: skeletal muscle reflexes

Question 1

skeletal muscle reflexes:
a
b

Answer 1

a. stretch reflex (muscle receptors)
b. golgi tendon reflex (tendon receptors)

Question 2

muscle receptors

Answer 2

stretch reflex

Question 3

tendon receptors

Answer 3

golgi tendon reflex

Question 4

sensory nerve fiber that sends messages back to the CNS from the muscle spindle

type of sensory fiber

Answer 4

1a fiber (muscle spindle)

Question 5

sensory fiber that is coming from the golgi tendon and sends message to CNS

Answer 5

1b fiber (golgi tendon)

Question 6

myelinated nerve fibers
large diameter
fastest conduction velocity

Answer 6

1a muscle spindle
1b golgi tendon

(sensory fibers)

Question 7

travels from cns to ends of muscle fibers in the spindle

Answer 7

gamma motor neuron (Ay) motor neuron

Question 8

two motor nuerons for skeletal muscle reflexes

Answer 8

alpha motor neuron (LMN)
and
gama motor neuron (Ay)

Question 9

innervates the ends of the intrafusal muscle fibers in the spindle

Answer 9

gamma motor neurons

Question 10

skeletal muscle fibers/cells that produce the contraction

Answer 10

extrafusal fibers

Question 11

efferent neuron that releases Ach and causes contraction of the extrafusal fiber (skeletal muscle)

Answer 11

alpha motor neuron (LMN)

Question 12

small structure within the extrafusal fibers that contain _____ that have sensory nerve endings wrapped around that are sensitive to changes in:

Answer 12

muscle spindle with 1a sensory fibers wrapped around

changes in MUSCLE LENGTH aka stretch

Question 13

1a sensory nerve fibers that are wrapped around muscle spindle are sensitive to changes in

Answer 13

muscle length aka stretch

Question 14

efferent neuron that causes contraction of intrafusal fibers so they mimic what the extrafusal fibers are doing

Answer 14

gamma motor neuron (found at the end of intrafusal fibers)

Question 15

as muscle stretches, this does what to 1a afferent neuron

Answer 15

increases AP frequency making it stretch

Question 16

jaw closers have a lot of:
jaw openers:

Answer 16

closers: lot of muscle spindles
openers: have few to none

Question 17

1. when the muscle stretches, the sensory fibers of the muscle spindle are

Answer 17

squeezed

Question 18

2. when afferent information enters the spinal cord:
   1
   2

which then stimulates:

Answer 18

1. this activates the alpha motor neuron (LMN)

which then stimulates
a. muscle contraction (extrafusal fiber)
b. inhibition of alpha motor neuron of antagonistic muscles

2. activates gamma motor neuron
   a. stimulates intrafusal fiber contraction
   b. if intrafusal fibers didn’t contraction, sensory fibers would not be able to sense a further change in muscle length since they would be slack

Question 19

afferent info entering spinal cord activates:

Answer 19

alpha motor neurons and gamma motor neurons

Question 20

the activation of alpha motor neurons stimulates:

Answer 20

muscle (extrafusal fiber) contraction
(also inhibition of the alpha motor neuron of antagonistic muscles)

Question 21

the activation of gamma motor neurons stimulates:

Answer 21

intrafusal fiber contraction

Question 22

if the intrafusal fiber doesn’t contraction from activation of gamma motor neuron, then the sensory fibers would not be able to

Answer 22

send a further change in muscle length since they would be slack

Question 23

the stimulus for the muscle spindle reflex is

Answer 23

stretch

Question 24

the effect of muscle spindle activation is

Answer 24

contraction

Question 25

the reflex has ______(immediate) and _____ (maintains tone-constant contraction) reflex components

Answer 25

dynamic and static

Question 26

dynamic: static:

Answer 26

dynamic: immediate static: maintains tone-contstant contraction

Question 27

anytime the alpha motor neuron is activated, what is also activated

Answer 27

gamma motor neuron

Question 28

if the ___________ did not contract, then the sensory fibers would not be able to sense a further change in muscle length since they would be slack

Answer 28

intrsfusal fibers

Question 29

with LMN and gamma activated together, this allows muscle spindle to maintain sensitivity to changes in

Answer 29

muscle length during contraction

Question 30

mechanosensitive receptors found at the junction of tendons and muscle

Answer 30

golgi tendon organs

Question 31

golgi tendon organs are sensitive to a change in

Answer 31

force

Question 32

the golgi tendon organ reflex is a

Answer 32

protective reflex

Question 33

if GTO (golgi tendon organ) is activated, it will

Answer 33

inhibit muscle contraction

Question 34

golgi tendon organ synapses with: which will then block activity of

Answer 34

inhibitory interneuron block 1a LMN

Question 35

tendons stretch in response to

Answer 35

contraction (particulary isometrix maximal contraction)

Question 36

extreme stretch of the tendon will squeeze the GTO and

Answer 36

afferent neurons will send info into spinal cord

Question 37

with an extreme stretch of GTO and afferent neurons sending info into spinal cord, what will happen:

Answer 37

1. stimulate inhibitory interneuron 2. this neuron decreases the activity of the alpha motor neuron LMN 3. skeletal muscle contraction is decreased= relaxation

Question 38

excess tension-> 1b to CNS-> stimulate inhibitory response-> neuron decreases LMN activity-> relaxation

Question 39

control of mastication is mix of

Answer 39

mix of voluntary, reflex, and central (subconscious) processes

Question 40

control of mastication requires coordination of muscles controlling:

Answer 40

lips, tongue and cheeks

Question 41

mastication voluntary control is usually ____, although people tend to favor one side of the mouth over the other

Answer 41

bilateral

Question 42

control component. mastication is a cyclical movement with develops early in life. it is controlled by

Answer 42

central pattern generator (CPG) of the brainstem

Question 43

when the central patten generator CPG of brainstem is stimulated, it elicits rhythmic, coordinated

Answer 43

activation and inactivation of jaw-closers and jaw-openers

Question 44

CPG cannot by itself adjust muscle force to deal with changing conditions that occur when diff food are chewed. ____ are important modifiers of force

Answer 44

reflexes

Question 45

input from higher cortical regions can regulate the CPG frequency via the to activate jaw closers and jaw openers

Answer 45

corticobulbar pathway

Question 46

pain inhibits the alpha motor neuron of jaw closing muscles such as when you bite down on your tongue, metal spoon, with your incisors

Answer 46

jaw opening reflex =jaw opens

Question 47

strong tap to the chin stretches the jaw closers -jaw closers respond by contraction so the jaw closes

Answer 47

jaw jerk reflex

Question 48

stretch reflex:

Answer 48

jaw jerk reflex

Question 49

how do you determine the force needed to take a bite of something hard? begins with

Answer 49

CPG starts chewing by activating jaw closer muscles

Question 50

GPG starts chewing by activating

Answer 50

jaw closer muscles

Question 51

when the jaw closing musclces connect with food, they initially meet with resistance:

Answer 51

the force of contraction is insufficient to overcome to load of food=isometric contraction!

Question 52

intrafusal fibers in muscle spindle are still contracting and stretching the muscle spindle so this signals further contraction of

Answer 52

jaw closing muscles

Question 53

constant feedback from the muscle spindle in the jaw closing muscles in sufficient to overcome the load of the food=

Answer 53

isotonic contraction

Question 54

with subsequent chewing strokes, the response is greater and matches the load of the food with appropriate force more

Answer 54

quickly

Question 55

protection by muscle spindles. With nut, lot of force is required and can damage intraoral structures. _______decreases contraction in these situations. when the nut cracks, the force is _____ than the load (nut) and there is MORE SLACK in the muscle spindle which leads to: so dont hurt teeth

Answer 55

muscle spindles force greater than load leads to less activation of the muscle (due to decreases alpha/gamma co-activation)

Question 56

powerful isometric contractions stimulate both jaw closing and opening muscles. the jaw _____ keep the jaw from snapping shut

Answer 56

jaw openers

Question 57

at rest, ____mm normally separate the occlusal surfaces of teeth

Answer 57

3-8mm

Question 58

when jog or run, ___ is applied to mandible. with each step, there is a ____ movement of the mandible in relation to the head. this movement stretches the_____ which causes a reflex contraction of jaw CLOSING muscles

Answer 58

force down movement muscle spindle