Question

a muscle or group of muscles opposing an action is called the: prime mover, antagonist, synergist, agonist
question 53
if the nerve impulse does not reach the required magnitude, only some of the muscle fibers will contract. true, false
question 54
whether or not a motor unit activates upon the arrival of an impulse depends on the

Explanation:

1. For the first question, an antagonist muscle opposes the action of another muscle. A prime mover is the main muscle causing an action, a synergist helps the prime - mover, and an agonist is the same as a prime - mover.
2. For the second question, according to the all - or - none law of muscle contraction, if the nerve impulse does not reach the threshold magnitude, no muscle fibers will contract, not just some. So the statement is false.

Answer:

1. B. antagonist
2. B. False