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๐ฌ Think about it
Your elbow only bends one way, but your shoulder swings all around.
Why can some parts move freely and others not?
The answer lies in the joints.
Let us observe our own movements first.
Why do some parts of the body move easily while others do not?
Joint
Junction of bones
where two or more bones meet
Allows movement
but cannot move the bones on its own
↓
A junction between two or more bones that allows movement; the type of joint decides what movement is possible.
- Every body part moves at a joint — a junction where two or more bones meet.
- Different parts have different types of joints, and the type of joint decides how much and in which direction the part can move.
- Some joints allow movement in many directions, so those parts move freely; others allow movement in only one direction or none, so those parts move less or not at all.
- Joints only allow movement — they cannot move the bones on their own; the muscles do that.
Example:
The shoulder joint lets the arm swing all around, while the elbow joint lets the arm bend only one way.
In this Activity, we will move different body parts and observe which movements each one can make.
Procedure
Move different parts of your body and observe what movement(s) each one can make. Record your findings in Table 3.5.
Table 3.5 — Different types of movements our body can make
| Body parts | Complete rotation | Partial rotation | Bending | Turning, side-raising, up-down or any other movement |
|---|---|---|---|---|
| Elbow | No | No | Yes | Up-down bending only |
| Shoulder | Yes | Yes | Yes | All directions |
| Knee | No | No | Yes | Up-down bending only |
| Neck | No | Yes | Yes | Side to side turning |
| Fingers | No | No | Yes | Bending |
| Toes | No | No | Yes | Bending |
| Wrist | No | Yes | Yes | Partial rotation |
Explanation
Some parts move easily in many directions, while others move only one way. The difference is due to the types of joints present. A joint is a junction between two or more bones. Joints allow movement but cannot move bones on their own — muscles do that.
โ Summary
In this activity, we learnt that:
- Moving each body part shows how it moves.
- Some parts move freely and some do not.
- Joints decide how each part moves.
Important Points
- A joint is a junction between two or more bones.
- The type of joint decides how a body part can move.
- Parts with freely moving joints (like the shoulder) move in many directions; parts with limited joints (like the elbow) move only one way.
- Joints allow movement but cannot move the bones on their own — the muscles move the bones.
โ Test Yourself
-
What is a joint?
View Answer
A junction between two or more bones. -
Why do some body parts move easily while others do not?
View Answer
Because they have different types of joints, and the type of joint decides the movement allowed. -
Which joint allows more movement — the shoulder or the elbow?
View Answer
The shoulder — it moves in all directions; the elbow bends only one way. -
Can joints move bones on their own?
View Answer
No — the muscles move the bones; joints only allow the movement.
Important Definitions
- Joint — a junction between two or more bones that allows movement.
