If the pleural cavity (the space outside the lung) accumulates blood (hemothorax) or air (pneumothorax) or both (hemopneumothorax) then this is called a collapsed lung. These conditions do not always damage the lung but they might, or they might be the result of damage. Injuries to the chest wall are also distinct from but may happen with lung injuries. Chest wall injuries include rib fractures and flail chest. In flail chest multiple ribs are broken move independently of the rib cage.