Where is it located and how does it branch off?
The right main bronchus originates at the site of tracheal division — the bifurcation (bifurcatio tracheae, carina tracheae).
- Projection of the origin: Anteriorly, the bifurcation is projected onto the sternal angle (level of the second intercostal space); posteriorly, onto the IV–V thoracic intervertebral disc (projection onto the spine itself — V–VI thoracic vertebrae).
- Depth: In the bifurcation area, the depth is 6–12 cm.
- Angles of origin: The total angle of tracheal bifurcation is 55–60°. The right bronchus deviates from the median line significantly less than the left, forming an obtuse angle of about 155° with the trachea. Due to this, it appears as a natural continuation of the trachea.
Further down, the bronchus runs obliquely downward and laterally, as the hila of the lungs are located below the level of the bifurcation.
What is the structure of the wall?
The right main bronchus is shorter and wider than the left (average diameter is 2 cm).
- Cartilaginous framework: The base is formed by 6–8 cartilaginous semirings (cartilagines tracheales).
- Membranous part: The posterior wall of the bronchus lacks cartilage. This is the so-called membranous part (paries membranaceus), which contains smooth muscle fibers (m. trachealis).
- Mucous membrane: The inner surface is lined with a mucous membrane (tunica mucosa). It is covered with pseudostratified ciliated epithelium and contains mucous glands (glandulae bronchiales).
Topography and adjacent structures
The right main bronchus is in close contact with major vessels and nerves:
- Superiorly and posteriorly: At the level of the IV thoracic vertebra, the azygos vein (v. azygos) arches over the right bronchus and then drains into the superior vena cava.
- Anteriorly: In the bifurcation area, the right pulmonary artery (a. pulmonalis dextra) partially adheres to the bronchus.
- To the right: Along the right surface of the trachea and above the bifurcation in the paratracheal tissue runs the right vagus nerve (n. vagus dexter), and the superior vena cava lies above the bifurcation.
- Fascial apparatus: The trachea, bronchi, and esophagus are surrounded by a common esophagotracheal fascial sheath. It is densest at the bifurcation, forms stabilizing ligaments with the pulmonary vessels, and limits the interbronchial space.
- Regional lymph nodes: The regional nodes for the bronchus are the paratracheal, tracheobronchial, and bifurcation nodes.
Clinical and surgical significance
The anatomical features of the right main bronchus determine the specific nature of pathologies and surgical interventions in this area:
- Foreign body aspiration: Since the right bronchus is wider than the left and departs at a more obtuse angle, serving as an almost direct continuation of the trachea, foreign bodies enter it in 70% of cases.
- Right-sided pneumonectomy: During the removal of the right lung, the main bronchus is dissected up to the trachea. It is stapled with a mechanical suturing device (UO), clamped, and divided toward the peripheral part.
- Tracheal cancer: If the tumor extends to the right main bronchus and it cannot be mobilized for a safe anastomosis, circular resection of the tracheal bifurcation with right-sided pneumonectomy is recommended. Access is achieved via lateral thoracotomy through the 4th or 5th intercostal space.
Class and exam questions
How does the right main bronchus differ from the left?
It is shorter, wider (diameter about 2 cm versus 1.2 cm in the left), consists of fewer cartilaginous semirings (6–8 versus 9–12), and branches off the trachea at a more obtuse angle (~155°), representing its almost direct continuation.
Which vein arches over the right main bronchus?
Azygos vein (v. azygos). At the level of the IV thoracic vertebra, it arches over the right main bronchus and drains into the superior vena cava.
Why do foreign bodies more frequently enter the right bronchus?
This is due to its topography: the right bronchus is wider than the left and has a more vertical course, representing a natural continuation of the trachea. Because of this, foreign bodies enter it in 70% of cases.
What else to study on this topic
- Tracheal bifurcation (bifurcatio tracheae)
- Left main bronchus (bronchus principalis sinister)
- Azygos vein (v. azygos)
- Topography of mediastinal organs
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