Left lung
Pulmo sinister
Definition
The left lung is the respiratory organ located in the left hemithorax, responsible for gas exchange. It is smaller than the right lung, mainly because it lacks an accessory lobe and the heart occupies more space on the left side.
It is divided into two main lobes:
Cranial lobe: subdivided into cranial and caudal parts, located anteriorly and partially contributing to the cardiac notch.
Caudal lobe: larger, resting on the diaphragm.
The left lung has a convex costal surface in contact with the ribs and a flat mediastinal surface marked by the cardiac impression. It is ventilated by the left main bronchus, and its vascularization includes the pulmonary arteries and veins.
In dogs, cats, and ruminants, the left lung has no middle or accessory lobe, unlike the right lung. In humans, the left lung also has two lobes—upper and lower—separated by the oblique fissure.
References
König HE, Liebich HG. Veterinary Anatomy of Domestic Mammals: Textbook and Colour Atlas. 7th ed. Stuttgart: Thieme; 2020.
Dyce KM, Sack WO, Wensing CJG. Textbook of Veterinary Anatomy. 5th ed. St. Louis: Elsevier; 2017.
International Committee on Veterinary Gross Anatomical Nomenclature. Nomina Anatomica Veterinaria. 6th ed. Hannover: Editorial Committee, World Association of Veterinary Anatomists; 2017.
