Motion/path dectection

I am very new to arduino I would like to ask for some advice on means of detecting motion.

Is it possible to detect the movement of arms/hands with the sensor on either body and/or hands ? And also could detect the movement path from point A to B, whether it is in a circular or line motion?

How do I do that ?? Please advice...

You could do it with accelerometers.

Could you explain a little more ??

A bit like Wii controllers. Actually, a lot like Wii controllers.

They use accelerometers to detect movement, and these are interpreted as gestures. The accelerometers detect acceleration in three axes. So linear motion would have only a major component whose direction did not change. Circular motion would be trickier to detect. Note that an accelerometer is just that; it cannot sense constant velocity, though it will detect the constant acceleration (downwards hopefully) due to gravity.

Thank you !!! I will take a look at examples on accelerometers first. Will be if I have any more questions.