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Neurobio II - Exam 1 > Lecture 2 - LMN and muscles - Part II > Flashcards

Lecture 2 - LMN and muscles - Part II Flashcards

1
Q

Which spinal reflex occurs when your hand accidentally touches a candle flame?

A

Withdrawl/flexor reflex

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2
Q

What are the two types of muscle fibers in the muscle spindle?

A
  • nuclear chain and nuclear bag cells
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3
Q

What are nuclear chain cells?

A

nuclei aligned in a line, like a chain

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4
Q

What are nuclear bag cells?

A

nuclei concentrated as in a bag

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5
Q

What are the 3 functional types of proprioceptors in muscle spindle?

A
  • Nuclear bag cells
    > static: length
    > dynamic: Velocity
  • Nuclear chain cells: only static for length
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6
Q

What is the ration of bag-to-chain?

A

1:2

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7
Q

What is the sensory to motor transistor?

A

mirror neurons

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8
Q

What is the motor to sensory transistor?

A

Muscle Spindle

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9
Q

If there are 2 nuclear bag cells, how many nuclear chain cells are there?

A

4

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10
Q

What innervates LMN for extrafusal muscle cells?

A

Alpha motor neurons

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11
Q

What do we need to know about alpha motor neurons?

A

big, highly myelinated

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12
Q

What innervates LMN for intrafusal muscle cells?

A

Gamma motor neuron

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13
Q

What do we need to know about gamma motor neurons?

A

also large and heavily myelinated, but less than alpha

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14
Q

What is innervation of central nuclear bag and chain cells, both dynamic and static?

A

Ia

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15
Q

What do we need to know about primary / Ia innervation?

A

big, same type as alpha motor neurons, heavily myelinated, bag and chain both dynamic and static

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16
Q

What innervates static nuclear bag and chain cells?

A

II

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17
Q

What should we know about II innervation?

A

A beta, like gamma, still first and conduct APs, not as fast as Ia.

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18
Q

What do type II fibers NOT innervate?

A

Dynamic bag cells!!

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19
Q

What is everywhere in the body, and what is it for?

A

free nerve endings, protective mechanism

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20
Q

What is the function of the muscle spindle?

A

detection and adjustment of muscle length

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21
Q

Why do we need the muscle spindle?

A

feedback to the motor actions

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22
Q

What does the position sense (stretch) function of muscle spindle?

A

Proprioception is Ia and II from static nuclear bag and nuclear chain

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23
Q

What does the kinesthesia (velocity) of muscle spindle?

A

motor information Ia from dynamic nuclear bag cell

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24
Q

What muscle type does concentric contraction?

A

extrafusal

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25
What muscle fibers do concentric contraction?
intrafusal, specialized to recalibrate spindle to maintain sensitivity
26
Why do we need extrafusal muscles and intrafusal fibers for the muscle length adjustment?
- decrease dynamic stretch and Ia/II activities - reset Ia/II activity, detect and maintain muscle length
27
What happens with an isometric contraction in the muscle spindle?
increase Ia/II from the static nuclear bag and nuclear chain cells
28
Conscious proprioception from ______ to _____
DCMLs to S1
29
Unconscious proprioception: __________ ______ tract
Posterior spinocerebellar tract
30
What happens with an eccentric contraction?
increae Ia on dynamic nuclear bag cells
31
What tract does motor info with eccentric contractions?
Anterior spinocerebellar tract
32
What are the 5 components of a spinal/brainstem reflex?
- receptor - afferent: somatic or visceral sensory input - may or may not need interneurons: integration - Efferent: somatic or visceral motor output - Effector: muscles and glands
33
What is an intrasegmental reflex?
afferent and efferent at same level
34
What is an intersegmental reflex?
afferent and efferent at multiple levels
35
What are the major functions of the descending motor control tracts in the anterior funiculus?
gross motor and postural control
36
What is another name for the flexor reflex of cutaneous receptors?
withdrawal or nociceptive reflex
37
What are the stimuli with withdrawal reflex?
noxious
38
What are the afferent for withdrawl reflex?
- nociceptive axons (a-delta)
39
Where are the interneurons for withdrawl reflex?
in higher/lower segments
40
What is the reflex type with a withdrawl reflex?
intersegmental reflex, through lissauer's tract
41
What are the efferent componenets of the flexor reflex?
- flexors: excitatory input - extensors: inhibitory input
42
What is the effect of the flexor reflex?
away from the noxious stimuli!
43
Where can the flexor reflex ONLY happen?
in the UE
44
What is the stimuli of the crossed extension reflex?
noxious stimuli
45
What is the afferent component of the crossed extension reflex?
nociceptive axons (A delta)
46
What are the interneurons of the the crossed extension reflex?
alternating excitatory and inhibatory
47
What are the efferent components of the crossed extension reflex?
- ipsilateral: flexors excited / extensor inhibited (FLEXOR REFLEX) - Contralateral: extensors excited/ flexors inhibited
48
What is the effect of the crossed extension reflex?
- affected limb flex to withdrawal - unaffected limb extend to maintain balance
49
What is the afferent component of the patellar tendon reflex?
- muscle spindle in quads (Ia)
50
What are the efferents and effectors in the patellar tendon reflex?
alpha motor nerons to quads: Activation - myotatic reflex: monosynaptic - intrasegmental reflex: afferent and efferent at same level alpha motor neurons to hamstring: inhibition - through interneuron - intersegmnetal reflex: afferent and efferent at different levels
51
What is the total effect of the patellar tendon reflex?
knee jerk reflex
52
What is the cord segment for biceps? Nerve?
- musculocutaneous, C5
53
What is the cord segment for brachioradialis? Nerve?
- C6, radial
54
What is the cord segment for triceps? Nerve?
C7, radial
55
What is the cord segment for knee-jerk (patellar)? Nerve?
L4, femoral
56
What is the cord segment for Ankle-jerk (achilles)? Nerve?
S1, tibial - PF, CLONUS!
57
What is clonus?
a repetitive ankle jerk reflex (UMN injury)
58
What is the true deep tendon reflex?
GTO
59
What are the types of Golgi tendon organ interneurons?
- excitatory and inhibitory
60
What are the total effects of the GTO deep tendon reflex dependent on?
which interneuron is activated
61
What are the patterns with GTO reflex?
- temporal/serial and spatial/parallel
62
What kind of motor units will be inhibited with GTO reflex?
motor units exerting heavily
63
What is the principle used during GTO motor unit recruitment?
size principle
64
Why is the GTO reflex important?
- fine adjustments of force production during ordinary motor activities - initiate additional forms of autogenic inhibition at higher tension levels
65
What is the clinical presentation of the GTO reflex?
- clasp-knife effects
66
What is a clasp-knife effect?
constant resistance results in autogenic inhibition through the GTO reflex
67
What condition has the clasp-knife effect?
PKD
68
Which nerves innervate the muscle spinde?
- Gamma motor neuron - Ia - II - Free nerve endings
69
Can all reflexed be modulated by the UMN system?
YES
70
Where does Ia conduct signals to?
the spinal cord and then to various segments via the spinal refelx
71
What does Ia projecting to higher levels do?
conscious perception and unconscious information
72
How can the Ia signal be overwritten?
by higher-level cortical motor control systems
73
What is needed for some people to test DTRs?
distractions (hold hands, clinch teeth, etc)
74
What are central pattern generators?
- Foundational wired up for locomotion (APPs) - rhythmic alternating mobility patterns (GAIT)
75
Do CPGs need supraspinal control?
NO - cat still walks on treadmill normally with dissected spinal cord
76
When is the supraspinal signal needed with CPGs?
to initiate normal functions
77
Do CPGs need sensory feedback?
NO
78
Is stepping reflex a CPG?
Yes - Caudal M1 walking pattern
79
What are CPG neurons in the spinal cord?
propriospinal neurons, specialized interneurons
80
What is the fasciculus proprius?
tracts coordinating four limb locomotion
81
What are supraspinal signals?
Initiate and stop patterns of gait, reaching, grasping, etc.
82
With new research on CPGs and basal nuclei theres new hope for what dx?
TBI, PD, SCI
83
Where are the voluntary locomotor regions?
Continuous reticular formation system - 1 in diencephalon - 1 in midbrain
84
Where is the diencephalic locomotor region (DLR)?
in the thalamus
85
Where is the mesencephalic locomotor region (MLR)?
boundary of the midbrain and pons, pedunculopontine junction
86
How are the voluntary locomotor regions regulated?
through hierarchical control systems
87
What is the function of the voluntary locomotor regions?
functions to start and coordinate the CPGs
88
Why is there no muscle stretch reflex induced when lowering the backpack with the biceps stretched?
Higher level UMN motor control systems voluntarily inhibit the stretch reflex
89
Where are the two voluntary locomotor regions located in the CNS?
DLR: diencephalic locomotor region MLR: mesencephalic locomotor region/pedunculopontine

Neurobio II - Exam 1 (10 decks)

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