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Right main bronchus

The right main bronchus is the larger, shorter, and more vertical primary division of the trachea. It begins at the tracheal bifurcation (carina, T4–T5 level) and extends approximately 2–2.5 cm before dividing into the superior (eparterial) lobar bronchus and the middle and inferior (hyparterial) lobar bronchi. Because of its wider diameter, shorter length, and more vertical orientation, the right main bronchus is the most common site for aspirated foreign bodies. It lies posterior to the ascending aorta and superior vena cava, and anterior to the esophagus.

Synonyms

  • Right primary bronchus

  • Right mainstem bronchus

  • Principal bronchus (right side)

Function

  • Conducts inhaled air from the trachea to the right lung

  • Distributes airflow to the three right lobes via its lobar and segmental branches

  • Protects airway via mucociliary clearance and cough reflex

  • Acts as a common site for aspiration, obstruction, or tumor involvement due to its anatomy

MRI Appearance

T1-weighted images:

  • Lumen appears as a signal void (black) due to air

  • Bronchial wall appears as a thin, low-to-intermediate signal rim

  • Surrounded by hyperintense mediastinal and hilar fat, providing natural contrast

T2-weighted images:

  • Air remains signal void

  • Bronchial wall shows intermediate signal; thickened walls from inflammation or tumor appear hyperintense

  • Adjacent mucus or fluid appears bright hyperintense

STIR (Short Tau Inversion Recovery):

  • Suppresses fat, improving visibility of peribronchial edema, inflammation, or tumor spread

  • Bronchial wall pathology becomes more conspicuous against suppressed background

T1 Post-Contrast (Gadolinium-enhanced):

  • Normal bronchial wall shows thin, uniform enhancement

  • Pathological changes (infection, tumor, granulation tissue) demonstrate irregular or asymmetric enhancement

  • Useful for identifying peribronchial tumor invasion or inflammatory thickening

CT Appearance

Non-contrast CT:

  • Right main bronchus is visualized as a tubular air-filled structure extending from the carina into the right lung

  • Air = hypodense (black); wall = thin soft tissue density

  • Wall thickening, narrowing, or obstruction is easily detected

Contrast-enhanced CT (CECT):

  • Enhances surrounding hilar vessels, clearly delineating the bronchus

  • Allows detection of masses, wall thickening, extrinsic compression, or lymph node involvement

  • CT is the gold standard for evaluating airway anatomy, stenosis, tumors, foreign bodies, and post-surgical changes

MRI image

Right main bronchus anatomy mri coronal image -img-00000-00000

CT images

Right main bronchus anatomy CT axial image -img-00000-00000