Bones and Muscles
How do muscles and bones work together to move the arm?
A complete explanation of how the two arm muscles contract and relax in turn, how muscles pull bones, where the elbow joint is, and how to carry out a safe observation activity.
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- 1-1 Bones and Muscles
What happens to our muscles when we bend and straighten our arms?
- Looking Inside the Arm
Which part is hard and strong, and which part is soft and flexible?
- How Does a Muscle Move a Bone?
Follow the effect of contraction step by step
- Muscle Contraction and Relaxation
Compare the two states of a muscle during arm movement
- When the Arm Bends
Look at the front and back muscles: what state is each one in?
- When the Arm Straightens
What changes between bending and straightening?
- Where Do Bending and Straightening Happen?
Move from the outside of the arm to its bones
- Extension: How Does the Pull Reach the Bone?
Find the connection between muscle and bone
- Activity: Observe Our Muscles
Watching the screen is always enough
- First Observation: Bending
During bending, which muscle feels firmer: the front muscle or the back muscle? Why?
- Second Observation: Straightening
How does the front muscle change as we move from bending to straightening? What happens to the back muscle?
- Compare Bending and Straightening
Compare bending and straightening, then predict the effect of a load
- Compare the Effect of Two Loads
Understand the idea on screen; do not lift weights
- Build Your Complete Explanation
Explain in one complete sentence: how does contraction of an upper-arm muscle move the forearm at the elbow?