http://www.ck12.org Chapter 1. Human Biology
FIGURE 1.19
The biceps and triceps act against one another to bend and straighten
the elbow joint. To bend the elbow, the biceps contracts and the triceps
relaxes. To straighten the elbow, the triceps contract and the biceps relax.Vocabulary
- extensor: Muscle that contracts to cause a joint to straighten.
- flexor: Muscle that contracts to cause a joint to bend.
- tendon: Tough connective tissue that attaches muscle to bones.
Summary
- Muscles move the body by contracting against the skeleton.
- Muscles work together in pairs to bend or straighten the joint.
Practice
Use the resource below to answer the questions that follow.
- Muscles and Movementat http://www.youtube.com/watch?v=1SGM06DiXLc (1:38)
MEDIA
Click image to the left for more content.- How does the biceps muscle move when you bend your arm? How does the triceps muscle move when you
bend your arm? - How does the triceps muscle move when you straighten your arm? How does the biceps muscle move when
you straighten your arm? - Why can muscles only pull and not push? How is this related to muscles working in pairs?
Review
- How are skeletal muscles attached to the skeleton?
- Explain why many skeletal muscles must work in opposing pairs.