Lung roots (anatomy)

The lung roots are the regions apposing the mediastinal surfaces of the lungs on each side where there is transit to and from the lung of:

• bronchi
• pulmonary arteries
• pulmonary veins
• bronchial vessels
• sympathetic nerves
• parasympathetic nerves
• lymphatics

The region of the lung where the root joins it is termed the hilus; it is approximately central upon the diaphragmatic surface of the lung. The root is ensheathed by the parietal pleural layer where it merges with the visceral pleura at the isthmus; it forms a layer which hang down into a loose fold inferiorly. This fold, the pulmonary ligament, provides room for expansion during increased flow of blood through the root.

The roots on each side have a slightly different arrangement of structures across its surface; this is discussed in the submenu.

The relations of the roots include:

• anteriorly: phrenic nerve
• posteriorly: vagus nerve
• superiorly:
  • arching over on the right, the azygous vein
  • arching over on the left, the aorta