The chest cavity is
A closed space. Taking a breath changes the internal pressure to negative, and air isdrawn in through the trachea.
If the chest wall is breeched, air is drawn in through the hole, or if the lung has weak point, the pressure equilibrium is lost, and the lung deflates, like a tire with a hole in it, and collapses. It can also occur if the trachea or bronchus is blocked.