What arm?
Bones will not cause the arm to be in a straight position, instead, muscle and tendons will cause the arm to be straight.
The bones will heal in the wrong position therefore the elbow might not be able to bend and move. If this happens, the way some doctors reset the arm is by re-breaking the elbow then setting the arm in the correct position in surgery.
when you bend your arm
Move your arm in circles
Reset the wiper arm. At the bulkhead end of the arm is a big nut on a tapered shaft. (might be under a cover). Slacken the nut and loosen the arm from the tapered shaft. Move the wiper to a different position on the windshield and tighten the nut. Test wiper to see that blade returns to the new position.
The humerus bone is the one in your upper arm, and it is needed when you want to move your arm.
Which muscles? If all the muscle are clenched it will be perfectly still but that could be in any position depending on what position the arm was in ot start with.
extention
Nerves
With muscles!
it helps to keep your body balanced as you walk
Yes. lol If you have an elbow or your arm isn't broken you can move it!