When a muscle contracts, the bone that moves is called the muscle's insertion point.
当肌肉收缩时,移动的骨骼称为肌肉插入点。
Crash Course 解剖生理学篇
When she pushes herself up, her pectoralis major is contracting, pulling its insertion point — which in this case is the top of her humerus — toward the immobile origin, which is her sternum.