Medial Surface Of The Lungs
The medial (mediastinal) surfaces of the right and left lungs present concave mirror images of the right and left sides of the mediastinum so that in addition to the structures forming the root of the lung, the medial lung surface presents distinct impressions made by the structures constituting the mediastinum (see Plates 1-18 and 1-19).
Medial Surface Of The Right Lung
The oblique and horizontal ﬁssures (if complete) divide the right lung into upper, middle, and lower lobes. The pleura reﬂects directly from the parietal to the visceral surface around the root of the lung except where it forms the pulmonary ligament, which extends from the inferior aspect of the root vertically down to the medial border of the base of the lung.
The main structures forming the root of the right lung are the superior and inferior pulmonary veins, which are situated anterior and inferior to the pulmonary artery, and the bronchus, which is posterior in position. A number of lymph nodes are also present.
Much of the ventral and inferior portions of the mediastinal surface show the impression caused by the heart. Superior to this is the groove caused by the superior vena cava, with the groove for the right brachiocephalic (innominate) vein above that. Near the apex of the lung is the groove for the right subclavian artery. Arching over the root of the lung is the groove caused by the azygos vein. Superior to this are the areas for the trachea (anteriorly) and the esophagus (posteriorly). The area for the esophagus continues inferiorly posterior to the root of the lung.
Because the inferior margin of the outer, costal surface of the lung extends downward farther than the lower margin of the medial surface, the diaphragmatic surface of the lung can also be seen when the medial aspect of the lung is observed.
Medial Surface Of The Left Lung
The oblique ﬁssure (if complete) divides the left lung into upper and lower lobes. The relationship of the pleura to the root of the left lung is similar to that on the right.
Structures forming the root of the left lung are the pulmonary artery superiorly, the bronchus posteriorly, and the superior and inferior pulmonary veins anteriorly and inferiorly. Some lymph nodes are also present. A large impression caused by the heart is present anterior and inferior to the root of the lung. It is responsible for a rather marked “cardiac notch” in the anterior border of the upper lobe of the left lung. Inferior to this notch is a projection of the upper lobe, the lingula.
Arching over the root of the left lung and continuing inferiorly—posterior to the root—to the base of the lung is a groove for the aortic arch and the descending aorta.
Superior to the groove for the aortic arch are, from behind forward, areas for the esophagus and trachea, the groove for the left subclavian artery, the groove for the left brachiocephalic (innominate) vein, and a groove caused by the ﬁrst rib.
The portion of the medial surface of the left lung posterior to the areas for the descending aorta and esophagus is in contact with the thoracic vertebral bodies and the vertebral ends of the ribs except where separated from them by structures lying in the position described above.
As on the right side, the diaphragmatic surface of the left lung can be seen as the medial aspect of the lung is observed.