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What you will learn...Forces Affecting Joints How to think of 1st and 3rd class levers. In human movement, stability must be sustained in a joint or dislocation, injury and degeneration occurs.
1st Class levers create a vice- like force within the joint. This is good because the joint is stabilized.
3rd Class levers create a dislocating force within the joint. This is bad because the joint becomes unstable.
The 1st Class PackageThe pull comes with the push. There is simple stabilization and good mechanical advantage. The 3rd Class PackageThe pull does not come with the push. Other parts and/or pulls are needed to make vice-like stabilization. Complex stabilization mechanisms are needed and there is poor mechanical advantage. |