In my way of thinking there is some space in there between the collapsed lungs (squeezed up by diaphragm) and the mesentery holding the other organs in place, granted the space is smaller than with lungs inflated but there has got to be some room there for an arrow or bullet to penetrate without hitting any vitals!
At the end of the
exhalation phase,
the lungs are still occupying the entire space within the chest cavity, the volume of the chest cavity is just momentarily smaller, but the lungs are still occupying that entire space. The pressure within it increases also.
