156 days ago,
The shoulder and arm receives its nerve supply through the brachial plexus. The brachial plexus is a complex network of nerves which come out of the neck, passes down to the front of the shoulder and then splits into many separate nerves to travel to different muscles and parts of the skin. Normally an arm movement is produced by initially thinking of the movement, then a message passes from the brain, down through the spinal cord to the appropriate nerve. Then the instruction to move is conveyed along the nerve to the specific arm muscle which then contracts and moves the arm.