Chapter 34, Problem 9STP

Summary Introduction

To describe:

The ways in which movement is allowed in the arm by biceps and triceps.

Introduction:

Bones move as muscles of the backbone contract. Muscles will contract only. They cannot deliberately stretch, but they can move or relax in a neutral position. Therefore pairs of muscles have to operate in contrast to move bones in the opposite direction. The muscles of each pair work to shift the bones at the articulation of the body against the other. The bending muscle of the joint is called the flexor.   The muscle which straightens the joint is referred to as the extensor. The other muscle of the pair is still elongated when one is a contract.

Explanation of Solution

The muscles of Biceps and Triceps work together to make our elbow bend and straighten. When we curve our elbow, our biceps contract and the triceps contract at the same time. The biceps are the flexor and the triceps the elbow joint extensor. The quadriceps and hamstrings, for bending and straightening the knee and the pectorals and trapezius for moving arms and shoulders forward and backward, and are also the muscles that work together. Muscles are not used during everyday activities. For instance, due to gravitational lifting, biceps are used more than the triceps.

Conclusion

Thus, the biceps and triceps allow movement in the arm.