The trachea bifurcates into the right and left main bronchi at the level of the carina, supplying air to the right and left lungs respectively. Each main or primary bronchus enters the hilum of its lung and gives rise to secondary lobar bronchi, which further divide into tertiary segmental bronchi supplying the bronchopulmonary segment.
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Gross anatomy
The right main bronchus is wider, shorter and courses more vertically (25 degrees to the median plane) 3 when compared to the left main bronchus 1,2. It is approximately 2.5 cm long and 1.2 cm wide. 3 It reaches the root of the right lung at the level of T5, lying inferolateral and posterior to the right pulmonary artery 1.
It gives rise to three lobar bronchi, initially bifurcating into right upper lobe bronchus and bronchus intermedius 1. Bronchus intermedius further divides into right middle lobe and lower lobe bronchi 1.
Relations
At right pulmonary hilum:
superiorly: arch of azygos vein
inferiorly: right pulmonary veins
anteriorly: right pulmonary artery (pulmonary veins anterior to pulmonary arteries)
posteriorly: esophagus (azygos vein posterior to esophagus)
Arterial supply
The right main bronchus is supplied by a single right bronchial artery 2. It arises from one of the following origins:
proximal part of one of the upper posterior intercostal arteries (commonly right third posterior intercostal artery)
a common trunk with the left superior bronchial artery
the descending aorta
Venous drainage
The right main bronchus drains into the right bronchial vein which drains into the azygos vein 4.
Variant anatomy
tracheal bronchus (pig bronchus)