Its upper lobar bronchus lies behind and above the right pulmonary artery-the structures at the root of the lung have different relationships in the right and left lungs. on both sides, the pulmonary veins are anterior and inferior while the bronchus is posterior. the difference between the two sides involves the pulmonary arteries. on the right side, the arteries are anterior to the bronchus, while on the left side the arteries are superior to the bronchus. the right lung is slightly larger than the left lung, and the lingula is found in the left lung only. neither lung is in the mediastinum-the mediastinum is the space between the two pleural sacs. finally, the phrenic nerve passes anterior to the root of the lung-on both the left and right sides.