Viscera (heart, lungs, liver, gastrointestinal tract)
Left main bronchus
Bronchus principalis sinister
- Origin
- Tracheal bifurcation at the carina (T4-T5 level)
- Insertion
- Passes inferolaterally beneath the aortic arch and anterior to the esophagus to enter the left lung hilum, dividing into superior and inferior lobar bronchi
- Function
- Conducts air to and from the left lung; narrower, longer (~5 cm), and more horizontally angled (~45°) than the right
- Innervation
- Pulmonary plexus (vagal parasympathetic bronchoconstrictors, sympathetic bronchodilators)
- Movement & chain
- Expands during inspiration and tracks lung motion
- Palpation
- Auscultated over the upper left anterior and posterior lung fields
- Clinical
- Less prone to foreign body aspiration than the right side due to horizontal takeoff angle. Extrinsic compression by left atrial enlargement or aortic arch aneurysm.
- Segmental innervation
- T2-T5 spinal levels
- In clinical practice
- Auscultation after intubation to rule out right mainstem intubation, bronchoscopic visualization, double-lumen tube placement for one-lung ventilation
- Region in the model
- Viscera (heart, lungs, liver, gastrointestinal tract)