Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BR 3rd Ed > Ch 5 - EDX Medicine and Clinical Neuromuscular Physiology > Flashcards

Ch 5 - EDX Medicine and Clinical Neuromuscular Physiology Flashcards

1
Q

Where is the cell body of a motor neuron located?

A

Anterior horn of the SC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Where is the cell body of a sensory neuron?

A

Located in dorsal root ganglion outside the SC in intervertebral foramen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is an axon?

A

Projection from sensory or motor neurons that propagate current flow and transport nutrition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where do axons of motor neurons project?

A

projects axons distal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Where do axons of a sensory neuron project?

A

Bipolar cells with 2 axons

1 projects proximal and one distal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the innervation ratio?

A

Amount of muscle fibers innervated by one axon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the innervation ratio of a muscles of gross movement?

A

High

The higher the ratio the higher the force

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is a myotome?

A

Group of muscles innervated by one spinal segement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is a dermatome?

A

Sensory innervation of one spinal segment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is a NMJ?

A

Sites where electric impulse along an axon converts to a chemical rxn and translated to an electrical impulse at postsynaptic mem to initiate a muscle fiber action potential (AP)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is a motor unit?

A 
Anterior horn cell
Motor nerve axon
Peripheral nerve
NMJ
Muscle fibers
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the Henneman size principle?

A

Smaller alpha motor neuron has low threshold for excitation and is recruited first in voluntary contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe Type I muscle fibers

A

Small cell body
Thin diameter axon
Low innervation ratio
Slow twitch muscle fibers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe Type II muscle fibers

A

Large cell body
Thick diameter axon
High innervation ratio
Fast twitch muscle fibers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What type of fibers does EDX evaluate?

A

Ia (large, myelinated) fibers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does the cathode of EDX do?

A

Neg cathode attracts positive charges and lowers membrane potential allowing Na to rush through voltage-gated channels and generate an AP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How do cooler temperatures impact EDX?

A

Prolongs latency
Inc: amp, duration
Dec: CV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is saltatory conduction?

A

Propogation of current between myelin in Na channels in nodes of Ranvier

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is orthodromic recording?

A

AP recorded in direction of physiologic conduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is antidromic recording?

A

AP recorded in opposite direction of physiologic conduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How is a miniature endplate potential (MEPP) created?

A

Spontaneous release of Ach ~ 5 sec during resting state at NMJ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How is an endplate potential (EPP) produced?

A

nerve depolarization opens voltage-gated Ca channels and release Ach into synaptic cleft which inc # of MEPP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Describe a Type I muscle fiber

A 
Small
Dark
Early recruitment
Highly resistant to fatigue
Mild effort (4-8 hz)
Slow, prolonged firing freq
Fine, precise movements
Small innervation ratio
Small amp/duration
Aerobic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Describe a Type IIA muscle fiber

A 
Large
Dark
Late recruitment
Fatigue resistant
Intermed effort (20-30 Hz)
Fast, unsustained firing freq
Gross movements
Large innervation ratio
Large amp/duration
Anaerobic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is demyelination?

A

Injury to myelin sheath but axon remains intact resulting in slower signal conduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is conduction block?

A

Failure of an AP to proprogate past an area of demyelination along axon that is structurally intact

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

How does conduction block present on NCS?

A

> 50% drop in CMAP b/w proximal and distal stimulus sites across area of injury

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What are the EDX findings of Demyelination on NSC?

A

Prolonged latency
Dec CV
Inc temporal dispersion
Dec amp across site of injury

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What are the EDX findings of Demyelination on EMG?

A 
Normal insertional activity
Normal resting activity
\+/- myokymia
\+/- dec recruitment
Normal MUAP
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is axonal degeneration?

A

Degeneration of axon starts distally and ascends proximally

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is Wallerian degeneration?

A

At site of nerve lesion, axon degenerates distally

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

How long does Wallerian degeneration take?

A

Motor axons: 7 days

Sensory axons: 11 days

33
Q

What are the EDX findings of axonal injury on NSC?

A

Normal latency
Dec amp
Normal temporal dispersion
Mild dec CV

34
Q

What are the EDX findings of axonal injury on EMG?

A

ABN insertional activity
ABN resting activity
Dec recruitment
ABN MUAP

35
Q

What is collateral sprouting?

A

Neurite sprouts off axon of an intact motor unit to innervate denervated muscle fibers of an injured motor unit

36
Q

How long does axonal regrowth take?

A

1 mm/ day

1 inch/month

37
Q

Describe regrown axons

A

Dec diameter
Thinner myelin
Shorter internodal distance

38
Q

Describe reinnervation on EMG

A

Low amp
Long duration
Polyphasic potentials (nascent potentials)

39
Q

What are the types of nerve injury based on Seddon Classification?

A

Neuropraxia
Axonotmesis
Neurotmesis

40
Q

Describe Neuropraxia

A

Nerve compression
Axon intact
Local myelin injury
Conduction block

41
Q

What is seen on NSC in Neuropraxia?

A

Signal normal distal to lesion

ABN proximal/across lesion

42
Q

What is seen in EMG in Neuropraxia?

A

normal/dec recruitment

43
Q

Describe Axontmesis

A

Nerve crush injury
Axonal disruption
CT/Scwann cell intact
Conduction failure

44
Q

What is seen on NSC in Axontmesis?

A

No conduction proxmial/distal to lesion wk-months after injury

45
Q

What is seen on EMG in Axonotmesis?

A

ABN activity

46
Q

Describe Neurotmesis

A

Nerve transection injury
Axonal interruption
CT disruption
Conduction failure

47
Q

What is seen on NSC in Neurotmesis?

A

No conduction proximal/distal to lesion after 2 weeks

48
Q

What is seen on EMG in Neurotmesis?

A

ABN activity

49
Q

What is the Suderland Classification of nerve injury

A 
Type 1: conduction block 
Type 2: Axonal injury
Type 3: type 2+ endoneurium injury
Type 4: type 3+ perineurium injury
Type 5: type 4+ epineurium injury
50
Q

What does the cathode of the stimulating electrode do?

A

Generates a - impulse and attracts + charges from the axon

51
Q

What does the anode of the stimulating electrode do?

A

Generates a + impulse and attracts - charges from the axon

52
Q

What is anodal block?

A

Reversing stimulator’s cathode and anode hyperpolarizes the nerve and inhibits generation of AP

53
Q

What is threshold stimulus?

A

Electrical stimulus sufficient to produce potential from a nerve

54
Q

What is maximal stimulus?

A

Electric stimulus in which no further increased evoked potential will occur with added stimulus intensity

55
Q

What errors can occur with submaximal stimulus?

A

Falsely lower amp & prolonged latency

can give impression of axonopathy or conduction block

56
Q

What is the supramaximal stimulus?

A

Electrical stimulus intensity at leaset 20% above maximal stimulus

57
Q

What can too high of a stimulus intensity lead to?

A

Decreased conduction times
Shortened latency
Altered waveforms
Amp unchaged

58
Q

How can stimulus artifact be minimized on NCS?

A

Placing ground electrode b/w recording electrode and simulator
Appropriate anode and cathode placement
Cleansing skin of dirt, perspiration and lotion

59
Q

What does the High Frequency (Low Pass) Filter (HFF) do?

A

Removes signals with frequencies higher than its cutoff setting and signals below not affected.
Affects faster portions of the summated waveforms

60
Q

What does the Low Frequency (High Pass) Filter (LFF) do?

A

Removes signals with frequencies lower than cut off and frequencies above not affected.
Affects slower portions of summated waveforms

61
Q

What are the filter settings for NCS and EMG?

A

Motor NCS: 2Hz-10kHz

Sensory NCS/EMG: 20Hz-10kHz

62
Q

What does increasing the LFF do to waveforms on NCS?

A

Reduces peak latency
Reduces amp
Changes potentials from bi- to triphasic
Does not change onset latency

63
Q

What does reducing the HFF do to waveforms on NCS?

A

Prolongs peak latency
Reduces amp
Creates longer negative spike
Prolongs onset latency

64
Q

What is the sweep speed?

A

Time allocated for each x-axis division and measured in miliseconds

65
Q

What is the sensitivity?

A

Height allocated for each y-axis and measured in milivolts (mV) or microvolts (uV).

66
Q

What is a normal sweep speed setting?

A

Sensory: 5 ms
Motor: 2 ms
EMG: 10 ms

67
Q

What is a normal sensitivity setting?

A

Sensory: 10 uV
Motor: 5 uV
EMG: 100 uV (insertional acitivity)
1 mV (recruitment pattern)

68
Q

What is the onset latency?

A

Time required for electric stimulus to initiate an evoked potential. Recorded from initial deflection from baseline

69
Q

What does onset latency reflect in sensory fibers?

A

Fastest fibers

70
Q

What does the peak latency represent?

A

Initiation of conduction along the majority of axons. Recorded at peak waveform

71
Q

What is conduction velocity?

A

Speed an impulse travels along a nerve dependent on myelin sheath

72
Q

What are the age variations in conduction velocity?

A

Newborns 50% of an adult
1 yo 80% of adults
3-5 yo equal to adults
Dec 1-2 m/s per decade >50yo

73
Q

What is considered a normal limb temperature for NCS?

A

Upper: 32 deg C
Lower: 30 deg C

74
Q

How does temperature affect CV?

A

Dec 2.4 m/s per 1 deg C drop

5% dec for each 1 deg C below 29 deg C

75
Q

What is amplitude?

A

Max voltage diff b/w two points reflecting # of nerve fibers activated and synchronicity of firing

76
Q

How is amplitude measured?

A

Peak-to-peak or baseline-to-peak

77
Q

How is duration measured?

A

Initial deflection from baseline to return

78
Q

What is the duration?

A

Summation and firing rate of numerous axons

BR 3rd Ed (92 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions