Right main bronchus

At a glance

English

Right main bronchus

Latin (TA2)

Bronchus principalis dexter

System

Respiratory

Region

Thorax

Side

Single, on the midline

About the right main bronchus

The right main bronchus is one of the two primary bronchi formed when the trachea divides at the carina, roughly opposite the sternal angle. Compared with its partner on the left it is shorter, broader and more upright, continuing almost in line with the trachea. These differences follow from the position of the heart and aortic arch, which push the left bronchus out to the side while the right one drops nearly straight down.

Its relations are close and important. Behind and above, the azygos vein hooks forwards over it on its way to the superior vena cava; the right pulmonary artery starts below the bronchus and then moves to its front. Only a couple of centimetres from its start, and before reaching the lung, it gives off the right superior lobar bronchus. Because this branch lies above the pulmonary artery it is called the eparterial bronchus. The continuing trunk, now below the artery, is the intermediate bronchus, which enters the hilum at about the level of the fifth thoracic vertebra and divides into the middle and inferior lobar bronchi. In total the right side therefore has three lobar bronchi for its three lobes.

Its wall resembles that of the trachea: C-shaped hyaline cartilage rings in front and at the sides, smooth muscle and fibrous tissue behind, and a lining of ciliated respiratory epithelium with goblet cells and glands that produce mucus and carry it up towards the larynx.

Its width and direction make it the airway that most often receives inhaled food, fluid or foreign objects, especially in a person lying flat, so aspiration pneumonia tends to affect the right lung. An endotracheal tube pushed too far also usually slips into this bronchus, so only the right lung is ventilated. A rare variant, the tracheal bronchus, sends the upper-lobe branch straight from the trachea.

Function and supply

Begins at

The bifurcation of the trachea at the carina, behind the sternal angle.

Ends at

Gives off the right superior lobar bronchus and continues as the intermediate bronchus to the hilum of the right lung.

Function

Conducts air between the trachea and the right lung, cleaning and humidifying it on the way.

Nerve supply

Pulmonary plexus, with vagal fibres that constrict the airway and stimulate glands and sympathetic fibres that relax it.

Blood supply

The right bronchial artery, usually from the third right posterior intercostal artery or the aorta; bronchial veins drain into the azygos vein.