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Posterior segmental bronchus of right lung

The posterior segmental bronchus of the right lung (B2) is one of the three segmental bronchi arising from the right upper lobar bronchus (secondary bronchus). It specifically supplies the posterior segment (S2) of the right upper lobe.

Anatomically, B2 branches posteriorly and laterally from the right upper lobar bronchus, passing toward the posterior part of the upper lobe, accompanying its corresponding pulmonary artery branch (A2) and vein (V2). Together, these structures define the bronchopulmonary segment.

The posterior segment is wedge-shaped and oriented posteriorly, making it an important landmark in bronchoscopic navigation, thoracic surgery, and radiological segmental analysis. Precise knowledge of B2 anatomy is essential for segmentectomy, lung cancer surgery, and interventional bronchoscopy.

Synonyms

  • Right upper lobe posterior segmental bronchus

  • B2 bronchus

  • Bronchus to segment S2 of right lung

Function

  • Conducts air to and from the posterior segment (S2) of the right upper lobe

  • Works with segmental arteries (A2) and veins (V2) to form the bronchopulmonary segment

  • Key structure for ventilation, gas exchange, and bronchoscopic orientation

Branches

  • Subsegmental bronchi (B2a, B2b ± B2c depending on variation)

    • Supply different subregions of the posterior segment (S2)

MRI Appearance

T1-weighted images:

  • Bronchial lumen appears as a signal void (black) when aerated

  • Walls show low to intermediate signal

T2-weighted images:

  • Aerated lumen remains hypointense (signal void)

  • Surrounding parenchyma is hyperintense in cases of consolidation or edema

STIR:

  • Suppresses surrounding fat, highlighting peribronchial pathology such as inflammation, edema, or tumor spread

T1 Post-Gadolinium (Gd-enhanced MRI):

  • Normal bronchial lumen does not enhance

  • Peribronchial soft tissues and pathological wall thickening show enhancement, useful in evaluating bronchial tumors or inflammatory disease

MRI Non-Contrast Cardiac/Respiratory-Gated 3D Imaging:

  • Provides 3D mapping of segmental bronchial tree including B2

  • Useful for pre-surgical planning and virtual bronchoscopy

CT Appearance

CT (High-resolution CT / HRCT):

  • Best modality to visualize B2 and its subsegmental branches

  • Lumen seen as an air-filled tubular structure with thin walls in the posterior upper lobe

  • Multiplanar reconstructions show relation to pulmonary vessels and intersegmental planes

CT Post-Contrast (CT Pulmonary Angiography / CT Bronchography):

  • Enhances surrounding vessels (A2, V2) and peribronchial tissues

  • Useful in evaluating bronchovascular relationships, compression, or invasion by tumors

  • Critical for surgical planning in segmentectomy and lobectomy

CT image

Posterior segmental bronchus of right lung CT axial image -img-00000-00000