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Right intermediate bronchus

The right intermediate bronchus is the continuation of the right main bronchus distal to the origin of the right upper lobar bronchus. It extends downward and slightly laterally before dividing into the right middle lobar bronchus and the right lower lobar bronchus. It is approximately 2 cm long and serves as a vital airway for the middle and lower lobes of the right lung. Anatomically, it lies in close relation to the right pulmonary artery and right pulmonary veins, making it an important landmark in bronchoscopy, thoracic imaging, and lung surgery.

Synonyms

  • Intermedius bronchus

  • Right interlobar bronchus

  • Bronchus intermedius

Function

  • Conducts air from the right main bronchus to the middle and lower lobes of the right lung

  • Provides ventilation for the right middle and lower lobes

  • Serves as a key bronchoscopic and surgical landmark for interventions in the right lung

  • Important site for endobronchial obstruction, foreign body aspiration, and tumor localization

CT Appearance

Lung Window:

  • Seen as an air-filled tubular structure extending downward from the right main bronchus to the hilum of the middle and lower lobes

  • Lumen is hypodense (black) with thin, normally imperceptible walls

  • Pathology: wall thickening in bronchitis, luminal narrowing in tumor or lymph node compression, mucus impaction, or airway obstruction with distal atelectasis

Mediastinal Window:

  • Bronchial wall is visible as a thin soft tissue rim

  • Provides better assessment of adjacent hilar vessels and lymph nodes

  • Useful for detecting extrinsic compression, peribronchial tumor spread, or lymphadenopathy

Contrast-enhanced CT (CECT):

  • Enhances bronchial walls and adjacent mediastinal vessels

  • High-resolution CT (HRCT) clearly delineates bronchial lumen, branching, and wall thickness

  • Essential for evaluating endobronchial tumors, post-obstructive pneumonia, and surgical planning

MRI Appearance

T1-weighted images:

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

  • Bronchial wall appears hypointense, surrounded by intermediate to hyperintense mediastinal fat

T2-weighted images:

  • Lumen remains a signal void if air-filled

  • Fluid or mucus within lumen appears bright hyperintense

  • Inflamed or thickened bronchial wall shows intermediate-to-high signal

T1 Post-Contrast (Gadolinium-enhanced):

  • Normal bronchial wall shows thin uniform rim enhancement

  • Pathological walls (tumor infiltration, granulomatous disease, infection) enhance irregularly and asymmetrically

  • Endobronchial lesions appear as enhancing intraluminal soft tissue masses

CT images

Right intermediate bronchus anatomy CT coronal image -img-00000-00000