- Aortic arch
- Left pulmonary artery
The left main stem bronchus is closely associated with the aortic arch, the left pulmonary artery and the esophagus.
The aorta is separated from the left main stem bronchus by the trunk of the right pulmonary artery.
The left pulmonary artery is short (2.5 cm), and runs obliquely posterior and proximal first across the anterior main stem bronchus, and then behind the origin of the left upper lobe bronchus. It thus forms a very long “S” which winds around the left main stem bronchus and the upper lobe bronchus.
The veins are located anterior to the bronchi but caudal to the pulmonary artery.
- Esophagus
The esophagus is adjacent to the proximal two centimeters of the left main stem bronchus.