How do the muscles, brain, and bones move our arm?

TN-06-Science.

http://inpeth.com/concept/2mfJZ3PNEDO...

Our hand is made of forearm and upper arm bones. Both of these bones are joined at elbow. Upper arm bones are covered with biceps muscles and triceps muscles. Bones are connected to muscles by a tissues called tendons.

When we want to lift something with our arm, our brain sends the signal to biceps muscle to contract and Triceps muscle to relax. When biceps contracts, it's length decreases and bone attached to it get pulled. In this process, relaxation of triceps muscle provide extra length so that bone can easily move.

Muscles apply pull force on bones by contraction which results in movement.