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ELECTROMYOGRAM

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EMG is performed by an electromyograph, which records an electromyogram. Electromyograph detects the electrical potential generated by muscle cells when ... – PowerPoint PPT presentation

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Title: ELECTROMYOGRAM


1
ELECTROMYOGRAM
  • Amit Sethi
  • Pre-doc Rehab Sciences,
  • MS OTR/L

2
INTRODUCTION
  • Electromyogram (EMG) is a technique for
    evaluating and recording the activation signal of
    muscles.
  • EMG is performed by an electromyograph, which
    records an electromyogram.
  • Electromyograph detects the electrical potential
    generated by muscle cells when these cells
    contract and relax.

3
INTRODUCTION Contd.
EMG Apparatus
Muscle Structure/EMG
4
ELECTRICAL CHARACTERITICS
  • The electrical source is the muscle membrane
    potential of about -70mV.
  • Measured EMG potentials range between
  • lt 50 µV up to 20 to 30 mV, depending on the
    muscle under observation.
  • Typical repetition rate of muscle unit firing is
    about 7-20 Hz.
  • Damage to motor units can be expected at ranges
    between 450 and 780 mV

5
ELECTRODE TYPES
  • Intramuscular -
  • Needle Electrodes

Extramuscular - Surface Electrodes
6
EMG PROCEDURE
  • Clean the site of application of electrode
  • Insert needle/place surface electrodes at muscle
    belly
  • Record muscle activity at rest
  • Record muscle activity upon voluntary contraction
    of the muscle.

7
EMG Contd.
  • Muscle Signals are Analog in nature.
  • EMG signals are also collected over a specific
    period of time.

Analog Signal
8
EMG Contd.
  • EMG processing

9
APPLICATION OF EMG
  • EMG can be used for diagnosis of Neurogenic or
    Myogenic Diseases.
  • You tube link of EMG

10
SAMPLE EMG DATA
11
BIOMECHANICS
  • Biomechanics is the research and analysis of the
    mechanics of living organisms.
  • KINEMATICS The branch of Biomechanics concerned
    with describing the motion of bodies.
  • KINETICS- The branch of biomechanics concerned
    with explaining the causes of body motions.

12
KINEMATICS Contd.
  • Data is usually collected with Motion Capture
    Devices over a specific time period.
  • VICON
  • Motion Analysis Corporation
  • Qualysis

Typical Set up of Motion Analysis Lab
13
SAMPLE KINEMATIC DATA
14
SAMPLE KINEMATIC DATA
15
SAMPLE KINEMATIC DATA
16
KINEMATICS DATA ANALYSIS
  • Aim to identify the variability in reaching
    movement in normal and stroke individuals.
  • Outcome Variable Elbow Joint Angle.
  • Magnitude of variability was analyzed with Std.
    Deviation.
  • Structure of variability in elbow angles was
    computed via IE using MATLAB.
  • H Log2 (1/Pi)
  • Pi probability that a given event will
    occur. Pi a1/H.
  • Higher values of IE suggest - more uncertainty.
  • Lower values of IE suggest- less uncertainty
    (increased stability). of

17
RESULTS
  • Subject SD Pre SD Post IE Pre IE Post 1
    4.54 1.80 0.58
    0.80
  • 2 3.69 2.67 0.79
    0.50
  • Control SD 2.68 IE 2.33

18
CONCLUSION
  • Variability/Uncertainity in movement is higher in
    normals as compared to individuals with Stroke.
  • This variability could be correlated with
    adaptability in movement which is decreased upon
    nervous system damage in Stroke.
  • Large data is required to generalize these
    results.

19
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