Spinal Cord and Movement 2: Reflexes Lec19 Flashcards Preview

Neuroscience > Spinal Cord and Movement 2: Reflexes Lec19 > Flashcards

Flashcards in Spinal Cord and Movement 2: Reflexes Lec19 Deck (42)
Loading flashcards...
1
Q

Extrafuscal (normal) muscle fibers are innervated by 

A

α motor neurons

2
Q

Intrafuscal (muscle spindle / stretch receptors) fibers are innervated by

A

 γ motor neurons
and by Type Ia and Type II sensory neurons

3
Q

Spindles are arranged in ___ with extrafuscal muscle fibers

A

parallel

4
Q

what do γ motor neurons affect? 

A

only spindle stiffness, not contraction

5
Q

Muscle spindles send stretch signals via 

A

type Ia and type II neurons:

6
Q

 Type ___ central (bag) region

A

Ia:

7
Q

type ___ fire intensely at onset of stretch,

! then slows down.

A

1a

8
Q

type II firing is at what rate

A

static, increases linearly with increasing strethc

9
Q

Stretch reflex?

A

 muscle spindle senses stretch --> spinal cord --> original (homonymous)
and synergist (heteronymous) muscles excited and anatagonist inhibited to counter perturbation

10
Q

during stretch reflex, the Antagonist

muscle is___

A

inhbhited by interneruons

11
Q

Contraction response:

when extrafuscal muscle contracts,____fire to
shorten intrafuscal fibers

A

 the γ motor neurons 

12
Q

why do the  the γ motor neurons fire during contraction response? 

A

to shorten the intrafusal fibers and to keep them sensitive

13
Q

Golgi Tendon Organs (GTO) only fire when muscle ___

A

actively contracts

14
Q

muscle spindle cares about ___

A

length

15
Q

golgi tendon cares about ___

A

tension

16
Q

holgi tendon organs are receptors are ___ fibers

A

Type Ib

17
Q

golgi tendon organ receptors arranged in ____ with extrafuscal muscle fibers

A

series

18
Q

muscle spindle is the only afferent that ___

A

receives a nerve supply

19
Q

difference between gamma motor neurons and alpha MN?

A

gamma has a smaller soma and a lower conduction velocity

20
Q

____ motor.. innervate intrafusal not at center point
but lower down

A

gamma

21
Q

____ contraction makes the muscle spindle more sensitive to stim.

A

intrafusal

22
Q

sensory receptors on intrafusal fibers

A

type 1a and II

23
Q

___ receptor fires with stretch from distal muscle spindle 

A

type II

24
Q

biceps  and brachialis are examples of

A

agonists

25
Q

triceps and biceps are

A

anatagonists

26
Q

increased load about the elbow causes rotation

--> spindle in biceps are stretched -->

afferents sent to spinal cord activating the

A

biceps motor neurons

27
Q

when an anatagonist muscle is inhibited it is by a

 

A

1a inhibitory interneuron

28
Q

correction is ____ perturbation

A

resisting

29
Q

if you ___ of a spindle it becomes silent

A

reduce

30
Q

when alpha motor neuron is activated without ___ you get silent

A

gamma MN

31
Q

golgi tendon reflex involves the ___ interneuron

A

1b

32
Q

in golgi tendon reflex action

1b interneuron does what

A

excites the anatgonist muscle

inhibits the agonist muscle

33
Q

Flexion-crossed-extension reflex:

 if one limb reflexively withdraws, the limb across the midline ____ to keep you balanced.

A

extends

34
Q

Central pattern generators are defined as neurons that 

A

produce coordinated movements in the absence of higher inputs

35
Q

 in cats & humans central pattern generators are  for ___ movements

A

stepping

36
Q

central pattern generators are activated by (2)

A

2. stim of Mesencephalic Locomotor Region

2. noradrenergic inputs

37
Q

 if one limb reflexively withdraws, theipsilateral limb ____ to keep you balanced.

A

flexes

38
Q

central pattern input can be modified by

A

training

39
Q

with emg demonstration Low amplitude action potentials...could mean

A

lost neurons

40
Q

its difficult to activate a nerve AP with direct electrical stimulation but easy to

A

monitor or record

41
Q

emg -- Can only recruit a few motor units...suggests a

A

partial problem

42
Q

emg -- Spontaneous, non-rhythmic activity...suggests

A

dennervated muscle