Pleura (or Pleurae) and Pleural Cavity of the Lungs
Lungs Anatomy | Shapes and Surfaces of the Lungs
The two lungs are the primary organs of our respiratory system, each with characteristic shapes and surfaces.
Main characteristics of the lungs:
- The soft, elastic lungs occupy most of the thoracic cavity and are protected from injury by the surrounding the sternum and rib cage.
- Both right lung and left lung rest on the diaphragm muscle that separates the thoracic and abdominal cavities.
- A large portion of each lung consists of blood vessels (arteries, veins, & capillaries) and respiratory tubes (bronchi, bronchioles, & alveolar ducts).
- Most of the lung volume, however, is made of small clusters of alveoli. Each alveolus is a small, thin-walled, cup-shaped sac that protrudes from the smallest air ducts.
- There are approximately 300 million alveoli in each lung, and they are the regions where gases are exchanged with nearby capillaries.
- Due to the elevated position of the liver, the right lung is slightly (= 5 cm) shorter than the left lung. The left lung, however, has less volume because some space is taken up by the heart.
- Each lung is cone-shaped. The concave base rests on the diaphragm and the narrow apex projects under the clavicle.
- A double-walled, fluid-filled sac called the pleura envelops each lung and aids in the ventilation process.
- The anterior, lateral, and posterior lung surfaces lie adjacent to the ribs and are thus often referred to as the costal surface.
Mediastinal space and hilum:
- Between the lungs is the mediastinum. This large open space contains the heart, blood vessels, esophagus, nerves, trachea, and primary bronchi.
- Along the mediastinal surface of each lung is a depression called the hilum (or hilus).
- This is the region where the major blood vessels, bronchi, and nerves enter and leave the lung. Together, these structures form the root of the lung.
- A prominent indentation called the cardiac notch is also present along the mediastinal surface of the left lung. This indentation provides room for the apex of the heart.
Learn respiratory system anatomy fast and efficiently with quizzes and labeled diagrams.
An Overview of Lung Anatomy:
Test yourself on the anterior view of the lungs.
Test yourself while observing the shapes and surfaces of the lungs.
An Overview of the Shapes and Surfaces of the Lungs: