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ELECTROMYOGR

Evaluating and recording the activaof muscles.Jeyaganesh N

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Agenda

1.What is EMG ?2.Electrical

Characteristics.

3.History.4.

4.Procedure.5.Reference.

6.Few tips.

7.

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Dont get confused with

Electromyograph

Electromyogram

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What is EMG ?

It involves

testing ofelectrical activ

4.

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What EMG does ?

It checksthe healthof themusclesand the

nervesthatcontrolthemuscles.

An electromyograph detectelectrical potential genermuscle cells, when theseare both mechanically ac

at rest.The signals can be analyzeorder to detect medicalabnormalities or analyze biomechanics of human oanimal movement.,Another test known as Nerve Conduction Test is also pe.side by side

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Electrical Characteristics

vThe electrical source, is the musclemembrane potential of about -90

v

vMeasured EMG potentials range beless than 50 V and up to 20 to 3

depending on the muscle underobservation.

4.

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History

4.

1666 Francesco Redi, discovered a highly specialized muselectric ray fish .that generated electricity

1773Walsh, demonstrated that the eel fish s muscle tissugenerate a spark

.of electricity

1792Luigi Galvani, demonstrated that electricity could

.muscle contractions

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Lets ponder, In Depth..

Procedure

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2 Main Types

Surface EMGIntramuscular

EMG

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Surface / Intramuscular E

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Motor Unit

A motor unitis a-motor neu

When a motor unactivated, all ofibers contract

Groups of motor often work togcoordinate thecontractions o

muscle.

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Basic Block Diagram

Simulator

Electrodes

Amplifier

Oscillo

Time Calli

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EMG signal decompositio

Made up of superimposed motor unit acpotentials (MUAPs) from several motor EMG signals can be decomposed into th

constituent MUAPs. MUAPs from different motor units tend to

different characteristic shapes Notably MUAP size and shape depend on

the electrode is located with respect tofibers and so can appear to be differenelectrode moves position.

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Positioning of the electrod

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Variables obtained from E

raw EMG fipattern integrated

EMG(IEMG amplitude:

mean s

frequency ana e at ons p w t

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e at ons p w tmuscle

EMG activity &muscle force

EMG signalsmuscle fat

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Normal vs. Abnormal Resin EMG

norma esu ts

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norma esu tsNeuropathic

An action potential amplitude thatnormal due to the increased numfibres per motor unit because ofreinnervation of denervated fibre

An increase in duration of the actiopotential A decrease in the number of moto

the muscle (as found using moto

number estimation techniques)

http://en.wikipedia.org/wiki/Fibreshttp://en.wikipedia.org/wiki/Reinnervationhttp://en.wikipedia.org/wiki/Reinnervationhttp://en.wikipedia.org/wiki/Fibres

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Abnormal Results| Myopa

A decrease in duration of the actiopotential A reduction in the area to amplitud

of the action potential

A decrease in the number of motothe muscle (in extremely severe only)

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http://www.nlm.nih.gov/medlineplus/ency/article/0

http://en.wikipedia.org/wiki/Electromyography

Reference

http://www.nlm.nih.gov/medlineplus/ency/article/003929.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/003929.htmhttp://en.wikipedia.org/wiki/Electromyographyhttp://en.wikipedia.org/wiki/Electromyographyhttp://en.wikipedia.org/wiki/Electromyographyhttp://www.nlm.nih.gov/medlineplus/ency/article/003929.htmhttp://www.nlm.nih.gov/medlineplus/ency/article/003929.htm

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Few Tips.

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THANK YOU !