Left main bronchus 3087653 108945026 2007-02-18T00:00:13Z Caerwine 347371 restub {{Infobox Anatomy | Name = {{PAGENAME}} | Latin = bronchus principalis sinister | GraySubject = 237 | GrayPage = 1085 | Image = Illu_conducting_passages.jpg | Caption = Conducting passages. | Image2 = Gray961.png | Caption2 = Front view of cartilages of larynx, trachea, and bronchi. | System = | MeshName = | MeshNumber = | DorlandsPre = b_23 | DorlandsSuf = 12198348 | }} The '''left main bronchus''' (or '''left primary bronchus''', or '''left principal bronchus''') is smaller in caliber but longer than the [[Right main bronchus|right]], being nearly 5 cm long. It enters the root of the [[left lung]] opposite the sixth [[thoracic vertebra]]. It passes beneath the [[aortic arch]], crosses in front of the [[esophagus]], the [[thoracic duct]], and the [[descending aorta]], and has the left [[pulmonary artery]] lying at first above, and then in front of it. The left bronchus has no [[eparterial branch]], and therefore it has been supposed by some that there is no upper lobe to the left lung, but that the so-called upper lobe corresponds to the middle lobe of the [[right lung]]. ==Additional images== <gallery> Image:Lungs anatomy.png|Anatomy of lungs. Image:Gray622.png|The tracheobronchial lymph glands. Image:Gray1032.png|The position and relation of the esophagus in the cervical region and in the posterior mediastinum. Seen from behind. </gallery> ==External links== * {{eMedicineDictionary|left+main+bronchus}} * {{SUNYAnatomyFigs|19|08|02}} - "The divisions of the bronchus." {{Gray's}} {{respiratory-stub}} {{Lung}}