PNB 2274 Lab 5: Electromyography
Questions and Answers.
Skeletal Muscle Anatomy - Answer -Attached by tendons to the bones of the skeleton
-Composed of fascicles which contain bundles of muscle fibers called myofibrils
-Fibers innervated by branches of motor neurons
Motor Unit - Answer One motor neuron and all the individual muscle fibers it innervates
What initiates the contraction of skeletal muscle? - Answer -Action potentials in motor
neurons results in muscle AP and contraction
-Usually under voluntary control
-Results in AP in all innervated fibers
Electromyogram - Answer -Recording of the electrical activity of muscles
-Size and shape of waveform provide information about the ability of muscles to respond to
stimulation
Surface EMG - Answer -Electrodes are placed on the skin
-Receives data from all activated muscle fibers
Intramuscular EMG - Answer -Electrodes are inserted into the muscle (NOT done in lab)
-Provide more insight into electrical activity
Data Acquisition Processes - Answer Amplification
Filtering
Sampling
(Above three done by power lab hardware)
Display
Transducer - Answer -Used when input is not electrical (i.e. blood pressure, body
temperature)
-NOT needed in lab
Analog to Digital Conversion - Answer -Sampling of analog voltage at regular intervals
, -Allows for recognition and display by a computer
-NOT done by power lab hardware
Signal Conditioning - Answer Amplification and filtering of input by power lab hardware
Data Acquisition Software - Answer Controls hardware's recording and display of signal
Raw EMG - Answer Records the potential difference detected at the electrode
Integrated EMG - Answer -A running average of the raw EMG
-Used to quantify the signal
Reciprocal Activation - Answer -Simultaneous activation of an agonist and inhibition of an
antagonist muscle
-i.e. biceps and triceps
-Inhibition is not complete, antagonist may still be active
-Co-activation
Co-Activation - Answer -Results from reciprocal activation
-Assists with joint stabilization
Co-Contraction - Answer -Two muscles work antagonistically to maintain a pose
-DIFFERS from co-activation
Qualities of a Sound Hypothesis - Answer -Statement, not a question
-Independent and dependent variable
-Specific, able to be addressed with a single experiment
-Testable, results should support or refute the hypothesis
Electrode Placement - Answer -Ensure contact
-Avoid hairy areas
-Place electrodes away from tendons (thinner muscles, contamination)
-Place ground electrode far away from recording electrode
Scaling Data - Answer -Scale buttons located on the left of the trace
Questions and Answers.
Skeletal Muscle Anatomy - Answer -Attached by tendons to the bones of the skeleton
-Composed of fascicles which contain bundles of muscle fibers called myofibrils
-Fibers innervated by branches of motor neurons
Motor Unit - Answer One motor neuron and all the individual muscle fibers it innervates
What initiates the contraction of skeletal muscle? - Answer -Action potentials in motor
neurons results in muscle AP and contraction
-Usually under voluntary control
-Results in AP in all innervated fibers
Electromyogram - Answer -Recording of the electrical activity of muscles
-Size and shape of waveform provide information about the ability of muscles to respond to
stimulation
Surface EMG - Answer -Electrodes are placed on the skin
-Receives data from all activated muscle fibers
Intramuscular EMG - Answer -Electrodes are inserted into the muscle (NOT done in lab)
-Provide more insight into electrical activity
Data Acquisition Processes - Answer Amplification
Filtering
Sampling
(Above three done by power lab hardware)
Display
Transducer - Answer -Used when input is not electrical (i.e. blood pressure, body
temperature)
-NOT needed in lab
Analog to Digital Conversion - Answer -Sampling of analog voltage at regular intervals
, -Allows for recognition and display by a computer
-NOT done by power lab hardware
Signal Conditioning - Answer Amplification and filtering of input by power lab hardware
Data Acquisition Software - Answer Controls hardware's recording and display of signal
Raw EMG - Answer Records the potential difference detected at the electrode
Integrated EMG - Answer -A running average of the raw EMG
-Used to quantify the signal
Reciprocal Activation - Answer -Simultaneous activation of an agonist and inhibition of an
antagonist muscle
-i.e. biceps and triceps
-Inhibition is not complete, antagonist may still be active
-Co-activation
Co-Activation - Answer -Results from reciprocal activation
-Assists with joint stabilization
Co-Contraction - Answer -Two muscles work antagonistically to maintain a pose
-DIFFERS from co-activation
Qualities of a Sound Hypothesis - Answer -Statement, not a question
-Independent and dependent variable
-Specific, able to be addressed with a single experiment
-Testable, results should support or refute the hypothesis
Electrode Placement - Answer -Ensure contact
-Avoid hairy areas
-Place electrodes away from tendons (thinner muscles, contamination)
-Place ground electrode far away from recording electrode
Scaling Data - Answer -Scale buttons located on the left of the trace
