It begins with an involuntary spasm or sudden contraction of the diaphragm, the large dome-shaped muscle below our lungs that we use to inhale air.

它开始于一种无意识的痉挛或膈肌的收缩，膈肌是个大的、圆顶形的肌肉，位于肺的下方，用于吸入空气。