Lungs
The right lung consists of three lobes, the left lung has two.
The borders between the lung lobes do not run horizontally. It is important to be familiar with the projection of the different lung lobes onto the thoracic wall (Figures 6a to 6d). The upper lobe on either side is best assessed from the front of the thorax, whereas the lower lobe is best assessed from the back of the thorax. At the front one has to bear in mind the position of the heart on the left side of the thorax and the middle lobe on the right side.
Pleura
The pleural membranes surround the lungs; the visceral pleura covers and is attached to the lung whereas the parietal pleura covers and is attached to the thoracic wall. Under physiological circumstances only a small amount of fluid is found between the two pleurae.
Airways
Air that is breathed in follows the following anatomical route:
– nasal cavity and pharynx
– trachea
– bronchi
– bronchioles
– terminal bronchioles
– respiratory bronchioles
– alveolar ducts
– alveoli (pulmonary air sacs).
Figure 6a: Projection of the lung lobes – anterior
Figure 6b: Projection of the lung lobes – posterior
Figure 6c: Projection of the lung lobes – left flank
Figure 6d: Projection of the lung lobes – right flank