How do the muscles in your arm extend your arm outward?

Question

Quizplus · Accepted Answer

Muscles work in pairs, with one muscle contracting while the other relaxes. In order to extend the arm outward, some muscles in the arm must relax while others contract to pull the arm straight. This is how the muscles in your arm extend your arm outward. Choice A is incorrect because muscles cannot push on bones; they can only pull. Choice B is incorrect because tendons do not have the ability to pull the arm straight on their own. Choice D is incorrect because the top half of the bicep does not wrap around underneath the elbow and does not function like a rope and pulley system.

How Do the Muscles in Your Arm Extend Your Arm