The lungs are located in the thoracic cavity and extend from an area just above the clavicles to the diaphragm.
The lungs are subdivided into lobes:
- The right lung has three lobes: superior, middle, and inferior.
- The left lung has only two lobes (superior and inferior) because of the location of the heart.
The apex of the lung is the upper rounded portion.
The base of the lung is the lower portion which rests on the diaphragm.
The mediastinum is the area between the two lungs. It houses the heart and large blood vessels (aorta, pulmonary artery, and vena cava), as well as the esophagus, trachea, and some lymph nodes.
Pleural membranes consist of a serous lining called the pleura, named for its particular location.
- Visceral pleura is found on the outer surface of each lung.
- Parietal pleura is the membrane lining the chest wall.
Between the two is a space called the pleural cavity or intrapleural space. The membranes secrete a thin layer of serous fluid that creates the intrapleural space. The fluid lubricates, allowing the two pleural membranes to slide past one another, avoiding friction and discomfort.
This space is also called a potential space as it has the potential to accumulate excess fluid, blood, and air during abnormal circumstances.