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Posterior basal segmental bronchus of right lung (B10)

The posterior basal segmental bronchus (B10) is the most posterior and inferior segmental branch of the right lower lobar bronchus. It arises from the lower lobe bronchus after the superior (B6) and medial, lateral, and anterior basal segmental bronchi (B7–B9). The B10 bronchus courses posteroinferiorly to ventilate the posterior basal segment of the right lower lobe, which lies against the diaphragm and vertebral column. This segment is particularly important because it is a common site for aspiration pneumonia, bronchiectasis, and basal atelectasis, especially in bedridden patients due to gravitational drainage of secretions.

Synonyms

  • B10 bronchus

  • Right posterior basal bronchus

  • Posterior basal segmental bronchus of right lower lobe

Function

  • Supplies air to the posterior basal segment of the right lower lobe

  • Maintains ventilation and gas exchange in the posterior diaphragmatic and paravertebral lung region

  • Plays a key role in drainage of mucus and secretions, making it a frequent site for aspiration-related pathology

  • Acts as a landmark in bronchoscopy, segmentectomy, and lobectomy planning

CT Appearance

Lung Window:

  • B10 appears as an air-filled hypodense (black) tubular structure coursing posteroinferiorly toward the posterior costophrenic recess

  • Normal walls are thin and barely visible

  • Pathology: wall thickening (bronchitis), mucus impaction, bronchiectasis (dilated thick-walled bronchi), or obstructing endobronchial lesions

Mediastinal Window:

  • Bronchial wall seen as a soft tissue rim within the right lower lobe bronchovascular bundle

  • Better demonstrates adjacent vessels, hilar nodes, or extrinsic compression

  • Helps distinguish endobronchial vs. peribronchial pathology

Contrast-enhanced CT (CECT):

  • Enhances the bronchial wall and adjacent vessels

  • Useful for detecting endobronchial tumors, peribronchial spread of carcinoma, or vascular compression

  • HRCT provides detailed assessment of bronchiectasis, airway wall thickness, and small airway disease

MRI Appearance

T1-weighted images:

  • Air-filled lumen appears as a signal void (black)

  • Bronchial wall is a thin hypointense rim

  • Peribronchial fat and vessels provide anatomical contrast

T2-weighted images:

  • Normal air-filled lumen remains a signal void

  • If fluid, mucus, or pus is present, the lumen becomes bright hyperintense

  • Wall thickening or inflammation shows intermediate to high signal

T1 Post-Contrast (Gadolinium-enhanced):

  • Normal bronchial wall enhances minimally

  • Pathology (tumor, inflammation, granuloma, abscess) shows thickened, irregular, or nodular enhancement

CT images

Posterior basal segmental bronchus of left lung (B10) anatomy CT coronal image -img-00000-00000