Question

1. which of the following best describes the role of an agonist muscle? * 5 points

a. it relaxes while another muscle contracts
b. it stabilizes a joint during movement
c. it is the primary muscle responsible for movement
d. it prevents the body from moving during exercise

1. in which plane of motion does flexion and extension primarily occur? 5 points

a. sagittal plane
b. transverse plane
c. frontal plane
d. coronal plane

Explanation:

Question 1

• Option A: The muscle that relaxes while another contracts is an antagonist, not an agonist.
• Option B: Stabilizing a joint during movement is the role of a stabilizer (e.g., synergist or fixator), not an agonist.
• Option C: An agonist muscle is the primary muscle responsible for producing a specific movement (e.g., the biceps brachii as an agonist in elbow flexion).
• Option D: Preventing movement during exercise is not the role of an agonist; agonists facilitate movement.

• Option A: Flexion and extension (e.g., bending/straightening the elbow, hip, or knee) primarily occur in the sagittal plane, which divides the body into left and right halves and involves forward/backward movements.
• Option B: The transverse plane involves rotational movements (e.g., twisting the torso) or horizontal abduction/adduction, not flexion/extension.
• Option C: The frontal (coronal) plane involves movements like abduction/adduction (moving limbs away from/toward the midline) or lateral flexion, not flexion/extension.
• Option D: The coronal plane is the same as the frontal plane, so it also does not primarily involve flexion/extension.

Answer:

C. It is the primary muscle responsible for movement

Question 2