The root of the right lung lies behind the superior vena cava and part of the right atrium, and below the azygos vein.

That of the left lung passes beneath the aortic arch and in front of the descending aorta; the phrenic nerve, pericardiacophrenic artery and vein, and the anterior pulmonary plexus, lie in front of each, and the vagus nerve and posterior pulmonary plexus lie behind.

The chief structures composing the root of each lung are arranged in a similar manner from the front to the back on each side.

The visceral-parietal reflection surrounding the root of the lung extends downwards from the hilum to near the base of the lower lobe in a sleeve-like fold called the pulmonary ligament.

The pulmonary ligaments serve to anchor the larger lower lobes of the lungs in position and prevent potential torsion.