The lungs are divided into lobes, three in the right lung and two in the left. The right lung has superior, middle, and inferior lobes. The left lung has superior and inferior lobes.
The lungs are surrounded by a pleural membrane. This serous (dobule) membrane covers each lung separately. This is a back-up system for a critical organ, so that damage to one lung sac does not damage the other. Visceral pleura covers the lungs. The parietal pleura is attached to the chest wall. The space between the pleural layers is the pleural cavity. It is filled with pleural fluid that allows slippage during breathing.
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