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.
