PNB Practical 2 Study Guide Exam
Reviewed 2026/2027| 254 Real
Questions and Answers With
Rationales (BRAND NEW!!)
1. Lab 1: What are the two methods of recording? - ANSWER✔️✔️-There are
two methods of recording: you can either insert needle electrodes through
the skin into the muscle—for an intramuscular EMG—or you can place
electrodes on the skin surface for a surface EMG.
2. Lab 1: What kind of EMGs did we conduct in this lab? - ANSWER✔️✔️-
Although intramuscular EMGs provide more insight into muscle electrical
activity, we will conduct surface EMGs in our lab. This diagram shows a
recording conducted by a previous student who recorded an EMG from the
biceps muscles using surface electrodes. This raw data reflects the electrical
activity of all the neighboring muscle fibers activated at that time; perhaps
thousands of individual fibers. Since motor units fire asynchronously, you
can see that the signal looks very noisy.
3. Lab 1: What can we gain from the size and shape of the waveforms
measured? - ANSWER✔️✔️-From the size and shape of the waveforms
measured in EMG, we can then gain insight into the ability of the muscle to
respond when the nerves are stimulated.
For this reason, EMG has often been used in clinical settings. Often, EMG
testing is performed with another test, called a nerve conduction study,
which yields information on nerve function. In conjunction with EMGs,
these tests can help with the diagnosis of nerve compression or injury (such
as carpal tunnel syndrome), nerve root injury (such as sciatica), and other
problems of the muscles or nerves.
4. Lab 1: What is a good hypothesis? - ANSWER✔️✔️-A good hypothesis
should have several important features. It should be a statement, not a
question, although a strong, compelling question can be the genesis point of
a hypothesis.
, A focused hypothesis should feature one independent and one dependent
variable and should be specific and able to be addressed using a single
experiment.
Finally, a hypothesis should be testable such that a clear experimental result
can support or refute your hypothesis.
5. Lab 1: Describe the data acquisition system - ANSWER✔️✔️-In brief, the
signal of interest must be passed through the signal conditioning hardware
for amplification, filtering, sampling, and display. If the signal of interest,
instead of being electrical, has some other fundamental nature (for example,
blood pressure or body temperature), the signal must be converted into an
analog voltage by a device called a transducer. Since the EMG signal is
already a voltage signal, we don't need to use a transducer in this lab.
6. Lab 1: What will the signal of interest go through? - ANSWER✔️✔️-
amplification, filtering, sampling, and display
7. Lab 1: what does power lab monitor?
- What’s signal conditioning? - ANSWER✔️✔️-The EMG voltage, whose
amplitude usually varies continuously over time, is monitored by the signal
conditioning hardware, called Power Lab. Power Lab can modify the
signal; for example, if the signal is too small, it gets amplified; or if noise
contaminates the signal, the signal gets filtered. In general, these processes
are called 'signal conditioning'.
8. Lab 1: Describe analog to digital conversion - ANSWER✔️✔️-After signal
conditioning, the analog voltage is sampled by the hardware at regular
intervals, a process we call analog-to-digital conversion. This digitized
signal now can be recognized by a computer and displayed appropriately.
9. Lab 1: Describe integration - ANSWER✔️✔️-In our lab, we use a very
simple technique called integration—which sums up the raw EMG signal.
We integrate the raw EMG and display the overall activity level of the
signal. It is an easy way to smooth out individual spikes and to make the
time course of changing activity much clearer. This is done for you
automatically by the software.
,10.Lab 1: annotation record - ANSWER✔️✔️-During this lab, your major
responsibility will be to record an annotation record. You will learn how to
add comments to a recording at specific times to help with data analysis.
11.Lab 1: In this lab... - ANSWER✔️✔️-In this lab, we are going to examine
how EMG signal changes as demand, and thus force, increases. We are also
going to examine two different contraction paradigms: reciprocal activation
and co-contraction.
Record EMGs during voluntary muscle contractions, and investigate how
contractile force changes with increasing demand.
Examine the activity of antagonist muscles and the phenomenon of
reciprocal activation and co-contraction.
12.Lab 1: Define Reciprocal activation - ANSWER✔️✔️-During a reciprocal
activation, there is simultaneous activation of an agonist muscle and
inhibition of an antagonist muscle.
During flexion, the biceps (in green) is active while the triceps (in pink) is
inhibited. The reverse is true during extension. Notice that the inhibition is
not complete, as the antagonist muscles may still be active, depending on the
nature of the action—for example, the speed of the action. This
phenomenon, which is called co-activation, may assist with joint
stabilization during movement.
13.Lab 1: Define EMG
- What is it a technique for? - ANSWER✔️✔️-EMG is a technique for
recording the electrical activity of muscles.
14.Lab 1: The data recorded is known as - ANSWER -The data recorded
is called an Electromyogram (also known as an 'EMG' or 'Myogram').
15.Lab 1: Co Contraction - ANSWER -During co-contraction, the
simultaneous contraction of both the agonist and the antagonist muscles
around a joint hold a steady stable position to maintain a given posture. This
is evident at the right-hand side of the traces shown here, where EMG traces
show greater activation levels as co-contraction holds the arm steady with
increasing loads of books to be held.
, 16.Lab 1: Recording Tips - ANSWER -When attaching surface electrodes
on biceps and triceps, good contact of electrodes with the skin is extremely
important.
→ Poor placement results in noisy EMG signals.
Hairy areas of the skin should be avoided.
Place electrodes away from tendons; there are fewer and thinner muscle
fibers near tendons, which produce weaker electrically signals. Additionally,
tendons fall close to other muscle origins and insertions, therefore, these
locations are more prone to cross contamination from other muscles.
Ground electrode should be placed as far away from recording electrodes so
that the ground lead does not record activity from the bicep and tricep
muscle.
If you see a flat line, scale it accordingly.
17.Lab 1: What do the different channels show you? - ANSWER -The
lower channel in the Data panel shows the raw biceps activity; the upper
channel displays the integrated (root mean square: RMS) activity, calculated
from the raw signal. Integrated activity is commonly used in the assessment
of muscle function because it reflects the overall activity of the raw EMG
and is easier to quantify.
18.Lab 1: What happens to your EMG signal when you increase the contraction
strength? - ANSWER -When you increase the contraction strength, the
EMG signals increase in size (peak is higher).
19.Lab 1: During reciprocal activation, why is the antagonist muscle not
completely silent? - ANSWER -The antagonist muscle is not
completely silent because co-activation is in play. to put specifically, co-
activation is the contraction of an agonist and antagonist muscle in order to
provide stability.
20.Lab 1: Unlike the discrete waveform from an electrocardiogram, the
electromyogram waveform is irregular. Why do you suppose this is? -
ANSWER -An electromyogram waveform is irregular due to the fact
that it records the electrical activity of skeletal muscles. These skeletal
muscles contract asynchronously, causing an irregular waveform upon
contraction. On the other hand, an electrocardiogram records cardiac
Reviewed 2026/2027| 254 Real
Questions and Answers With
Rationales (BRAND NEW!!)
1. Lab 1: What are the two methods of recording? - ANSWER✔️✔️-There are
two methods of recording: you can either insert needle electrodes through
the skin into the muscle—for an intramuscular EMG—or you can place
electrodes on the skin surface for a surface EMG.
2. Lab 1: What kind of EMGs did we conduct in this lab? - ANSWER✔️✔️-
Although intramuscular EMGs provide more insight into muscle electrical
activity, we will conduct surface EMGs in our lab. This diagram shows a
recording conducted by a previous student who recorded an EMG from the
biceps muscles using surface electrodes. This raw data reflects the electrical
activity of all the neighboring muscle fibers activated at that time; perhaps
thousands of individual fibers. Since motor units fire asynchronously, you
can see that the signal looks very noisy.
3. Lab 1: What can we gain from the size and shape of the waveforms
measured? - ANSWER✔️✔️-From the size and shape of the waveforms
measured in EMG, we can then gain insight into the ability of the muscle to
respond when the nerves are stimulated.
For this reason, EMG has often been used in clinical settings. Often, EMG
testing is performed with another test, called a nerve conduction study,
which yields information on nerve function. In conjunction with EMGs,
these tests can help with the diagnosis of nerve compression or injury (such
as carpal tunnel syndrome), nerve root injury (such as sciatica), and other
problems of the muscles or nerves.
4. Lab 1: What is a good hypothesis? - ANSWER✔️✔️-A good hypothesis
should have several important features. It should be a statement, not a
question, although a strong, compelling question can be the genesis point of
a hypothesis.
, A focused hypothesis should feature one independent and one dependent
variable and should be specific and able to be addressed using a single
experiment.
Finally, a hypothesis should be testable such that a clear experimental result
can support or refute your hypothesis.
5. Lab 1: Describe the data acquisition system - ANSWER✔️✔️-In brief, the
signal of interest must be passed through the signal conditioning hardware
for amplification, filtering, sampling, and display. If the signal of interest,
instead of being electrical, has some other fundamental nature (for example,
blood pressure or body temperature), the signal must be converted into an
analog voltage by a device called a transducer. Since the EMG signal is
already a voltage signal, we don't need to use a transducer in this lab.
6. Lab 1: What will the signal of interest go through? - ANSWER✔️✔️-
amplification, filtering, sampling, and display
7. Lab 1: what does power lab monitor?
- What’s signal conditioning? - ANSWER✔️✔️-The EMG voltage, whose
amplitude usually varies continuously over time, is monitored by the signal
conditioning hardware, called Power Lab. Power Lab can modify the
signal; for example, if the signal is too small, it gets amplified; or if noise
contaminates the signal, the signal gets filtered. In general, these processes
are called 'signal conditioning'.
8. Lab 1: Describe analog to digital conversion - ANSWER✔️✔️-After signal
conditioning, the analog voltage is sampled by the hardware at regular
intervals, a process we call analog-to-digital conversion. This digitized
signal now can be recognized by a computer and displayed appropriately.
9. Lab 1: Describe integration - ANSWER✔️✔️-In our lab, we use a very
simple technique called integration—which sums up the raw EMG signal.
We integrate the raw EMG and display the overall activity level of the
signal. It is an easy way to smooth out individual spikes and to make the
time course of changing activity much clearer. This is done for you
automatically by the software.
,10.Lab 1: annotation record - ANSWER✔️✔️-During this lab, your major
responsibility will be to record an annotation record. You will learn how to
add comments to a recording at specific times to help with data analysis.
11.Lab 1: In this lab... - ANSWER✔️✔️-In this lab, we are going to examine
how EMG signal changes as demand, and thus force, increases. We are also
going to examine two different contraction paradigms: reciprocal activation
and co-contraction.
Record EMGs during voluntary muscle contractions, and investigate how
contractile force changes with increasing demand.
Examine the activity of antagonist muscles and the phenomenon of
reciprocal activation and co-contraction.
12.Lab 1: Define Reciprocal activation - ANSWER✔️✔️-During a reciprocal
activation, there is simultaneous activation of an agonist muscle and
inhibition of an antagonist muscle.
During flexion, the biceps (in green) is active while the triceps (in pink) is
inhibited. The reverse is true during extension. Notice that the inhibition is
not complete, as the antagonist muscles may still be active, depending on the
nature of the action—for example, the speed of the action. This
phenomenon, which is called co-activation, may assist with joint
stabilization during movement.
13.Lab 1: Define EMG
- What is it a technique for? - ANSWER✔️✔️-EMG is a technique for
recording the electrical activity of muscles.
14.Lab 1: The data recorded is known as - ANSWER -The data recorded
is called an Electromyogram (also known as an 'EMG' or 'Myogram').
15.Lab 1: Co Contraction - ANSWER -During co-contraction, the
simultaneous contraction of both the agonist and the antagonist muscles
around a joint hold a steady stable position to maintain a given posture. This
is evident at the right-hand side of the traces shown here, where EMG traces
show greater activation levels as co-contraction holds the arm steady with
increasing loads of books to be held.
, 16.Lab 1: Recording Tips - ANSWER -When attaching surface electrodes
on biceps and triceps, good contact of electrodes with the skin is extremely
important.
→ Poor placement results in noisy EMG signals.
Hairy areas of the skin should be avoided.
Place electrodes away from tendons; there are fewer and thinner muscle
fibers near tendons, which produce weaker electrically signals. Additionally,
tendons fall close to other muscle origins and insertions, therefore, these
locations are more prone to cross contamination from other muscles.
Ground electrode should be placed as far away from recording electrodes so
that the ground lead does not record activity from the bicep and tricep
muscle.
If you see a flat line, scale it accordingly.
17.Lab 1: What do the different channels show you? - ANSWER -The
lower channel in the Data panel shows the raw biceps activity; the upper
channel displays the integrated (root mean square: RMS) activity, calculated
from the raw signal. Integrated activity is commonly used in the assessment
of muscle function because it reflects the overall activity of the raw EMG
and is easier to quantify.
18.Lab 1: What happens to your EMG signal when you increase the contraction
strength? - ANSWER -When you increase the contraction strength, the
EMG signals increase in size (peak is higher).
19.Lab 1: During reciprocal activation, why is the antagonist muscle not
completely silent? - ANSWER -The antagonist muscle is not
completely silent because co-activation is in play. to put specifically, co-
activation is the contraction of an agonist and antagonist muscle in order to
provide stability.
20.Lab 1: Unlike the discrete waveform from an electrocardiogram, the
electromyogram waveform is irregular. Why do you suppose this is? -
ANSWER -An electromyogram waveform is irregular due to the fact
that it records the electrical activity of skeletal muscles. These skeletal
muscles contract asynchronously, causing an irregular waveform upon
contraction. On the other hand, an electrocardiogram records cardiac
