Interactive Guide to Physical Examination
Thorax & Lungs

Anatomy Review

Landmarks on the chest wall:

Anatomic landmarks on the chest wall are used to describe the location of findings during examination of the thorax, lungs, and cardiovascular system. It is useful to describe findings around the circumference of the chest in relation to a set of imaginary vertical lines and along a vertical axis in relation to ribs and interspaces. Remember that interspaces are numbered for the rib above. The underlying pulmonary parenchyma can be visualized in relationship to these chest wall landmarks.

View interactive module Click on the interactive icon for a review of anatomical landmarks.

The pleurae:

Remember that the lungs are lined by the visceral pleura while the inner rib cage is lined by parietal pleura. Normally, these layers are closely adherent to one another. The pleural space is therefore a potential space where fluid, pus, or blood can accumulate during pathologic disease states or with trauma.

Muscles of respiration:

Breathing is controlled by the brainstem. The primary muscle for inspiration is the diaphragm which descends with contraction thereby enlarging the thoracic cavity. The parasternals and the scalenes help expand the thorax during inspiration. The result being decreased intrathoracic pressure with air drawn through the tracheopulmonary tree.

With cessation of inspiration, the chest wall and lungs recoil, and the diaphragm rises to its resting position. With disease processes that cause labored respiration, accessory muscles aid in respiration. These include the sternomastoids, the scalenes, and abdominal wall musculature.