Question

Which of the following sets of antagonistic muscles is incorrect?
A. Flexor - Relaxor
B. Abductor - Adductor
C. Pronator - Supinator
D. Levator - Depressor

Answer 1

Hint: Antagonistic muscles are those muscles that when contracts provide opposite movements at an equivalent joint. When one pair of the muscle contracts it causes movement in a specific direction while when the other muscle contracts it causes the movement in other direction.

Complete Step by Step Answer:
There are around 650 muscles in our body and each muscle works in pairs. So each muscle represents a part of the pair of an identical muscle. When these muscles contract they cause movement in one direction and when the other muscle contracts it causes movement in the opposite direction. Such pairs of muscles are called antagonistic pairs. The contracted muscle is called agonist and the relaxed muscle is called antagonist. For example, the bicep and the tricep muscle of the forearm are the antagonistic pairs. As the bicep muscles contract they bring the forearm towards the upper arm. And now when the tricep muscle contracts it moves the forearm away from the upper arm that is opposite to the movement caused by the bicep. This is often called Flexor and extensor quiet muscles. Other such examples of antagonistic pairs are:- abductor - adductor, pronator - supinator, levator - depressor.

Thus, the correct answer is option A:- flexor - relaxor as they are not the antagonist pairs.

Note: Muscle tissues are soft and are referred to as myopropulsive tissues. The muscles are formed during embryonic development through a process called myogenesis. All the muscles are paraxial mesoderm in origin.