what does shoulders here mean?
Youngblood put Congressman Thornberry beside Curry, got in back with Johnson, and told the President to crouch below window level. Because Johnson obeyed, Thomas, emerging from the hospital, didn't see him. "Stop!" he shouted. "Keep going," Youngblood called to Curry. From the floor Johnson inquired, 'Who is it?" The agent told him, and Johnson, asserting himself for the first time, said, "Then stop." Making the best of the delay, Youngblood decided to use every inch of flesh as protection. He directed Thomas to sit in front, pulled Thornberry into the rear, and arranged Johnson's shoulders so that he was in the middle. Any bullet aimed at the President would first have to pass through Curry, one of the two Congressmen, or Youngblood.】
what does "arrange shoulders"mean?