Left main bronchus
Bronchus principalis sinister
RespiratoryOrgansThoraxLeft side
- What it is
- The left main bronchus runs more horizontally (about 45°), passing under the aortic arch and in front of the oesophagus and descending aorta to reach the left hilum.
- Function
- Carries air into the left lung, dividing at the hilum into the upper and lower lobe bronchi.
- Size
- About 5 cm long and 1.2 cm in diameter.
- Clinical note
- An enlarged left atrium or an aortic arch aneurysm can compress it; its length suits left-sided double-lumen tubes used in thoracic surgery.