Elastic Properties of the Chest Wall

Just as the lung is elastic, so is the thoracic cage. This can be illustrated by putting air into the intrapleural space (pneumothorax). Figure 7-10 shows that the normal pressure outside the lung is subatmospheric just as it is in the jar of Figure 7-3. When air is introduced into the intrapleural space, raising the pressure to atmospheric, the lung collapses inward, and the chest wall springs outward. This Figure 7-10. The tendency of the lung to recoil to its deflated volume is balanced by...