When a person straightens their arm out they are flexing the triceps brachii. During this movement the triceps is referred to as the _________.
A) agonist
B) antagonist
C) tendon
D) all of these
E) none of these

Question

Quizplus · Accepted Answer

The triceps brachii is the muscle responsible for straightening the arm out, which means it is the agonist muscle. An antagonist muscle would be responsible for the opposite movement, which in this case would be the biceps brachii. Tendon is a connective tissue that attaches muscle to bone, so it is not an appropriate answer for this question. Therefore, the correct answer is A) agonist.

When a Person Straightens Their Arm Out They Are Flexing