Editing Lung (section)

=== Left lung ===
The left lung is divided into two lobes, an upper and a lower lobe, by the oblique fissure, which extends from the [[rib|costal]] to the mediastinal surface of the lung both above and below the [[Hilum of lung|hilum]].<ref name=GRAYS /> The left lung, unlike the right, does not have a middle lobe, though it does have a [[Homology (biology)|homologous]] feature, a projection of the upper lobe termed the '''lingula'''.  Its name means "little tongue". The lingula on the left lung serves as an anatomic parallel to the middle lobe on the right lung, with both areas being predisposed to similar infections and anatomic complications.<ref>{{cite journal|pmid=21324708|year=2011|last1=Yu|first1=J.A.|title=Lady Windermere revisited: Treatment with thoracoscopic lobectomy/segmentectomy for right middle lobe and lingular bronchiectasis associated with non-tuberculous mycobacterial disease|journal=European Journal of Cardio-Thoracic Surgery|volume=40|issue=3|pages=671–675|last2=Pomerantz|first2=M|last3=Bishop|first3=A|last4=Weyant|first4=M.J.|last5=Mitchell|first5=J.D.|doi=10.1016/j.ejcts.2010.12.028|doi-access=free}}</ref><ref>{{cite journal|pmid=14718418|year=2004|last1=Ayed|first1=A.K.|title=Resection of the right middle lobe and lingula in children for middle lobe/lingula syndrome|journal=Chest|volume=125|issue=1|pages=38–42|doi=10.1378/chest.125.1.38|s2cid=45666843}}</ref> There are two [[bronchopulmonary segment]]s of the lingula: superior and inferior.<ref name=GRAYS />

The mediastinal surface of the left lung has a large ''cardiac impression'' where the heart sits. This is deeper and larger than that on the right lung, at which level the heart projects to the left.<ref name=GRAYS40TH />

On the same surface, immediately above the hilum, is a well-marked curved groove for  the [[aortic arch]], and a groove below it for the [[descending aorta]]. The [[subclavian artery|left subclavian artery]], a branch off the aortic arch, sits in a groove from the arch to near the apex of the lung. A shallower groove in front of the artery and near the edge of the lung, lodges the left [[brachiocephalic vein]]. The oesophagus may sit in a wider shallow impression at the base of the lung.<ref name=GRAYS40TH />

By standard [[reference range]], the weight of the left lung is {{convert|110-675|g|lb|abbr=on}}<ref name="MolinaDiMaio2012"/> in men and {{convert|105-515|g|lb|abbr=on}} in women.<ref name="MolinaDiMaio2015"/>