S2.3.3 For the adult
Muscles move bones
How does my arm bend and straighten?
What this chapter teaches
A muscle can only pull. It gets shorter and harder, and a tendon joins it to a bone. Muscles work in pairs: the biceps bends the arm and the triceps straightens it. A common mistake is to think a muscle can push.
Three questions to ask
There is no one right wording. Listen for the idea.
- Put a hand on your upper arm and bend your elbow. What do you feel happen?
- How does your arm straighten again if a muscle can only pull?
- Why do muscles need to work in pairs?
After the chapter, the learner can
- Feel a muscle get hard as it pulls on a bone
- Explain why muscles work in pairs to bend and straighten an arm
What they copy into their notebook
A muscle can only pull. It gets short and hard. A tendon joins it to a bone. The biceps bends your arm. The triceps straightens it. Muscles work in pairs.