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Anterior segmental bronchus of right lung

The anterior segmental bronchus of the right lung (B3) is one of the three segmental (tertiary) bronchi of the right upper lobe bronchus, alongside the apical (B1) and posterior (B2) bronchi. It arises from the anterior wall of the right upper lobe bronchus, coursing forward and slightly downward to supply the anterior segment (S3) of the right upper lobe.

The anterior segment includes much of the anteromedial surface of the upper lobe and contributes to the anterior border of the lung on chest radiographs. B3 travels with the anterior segmental artery (A3) and drains via the anterior segmental vein (V3), forming the bronchovascular bundle of the anterior segment.

This bronchus is a key surgical landmark in segmentectomy, lobectomy, and bronchoscopy, as well as in CT bronchographic reconstructions used for pre-operative mapping.

Synonyms

  • B3 bronchus

  • Right upper lobe anterior bronchus

  • Segmental bronchus to S3

Function

  • Supplies the anterior segment (S3) of the right upper lobe with airflow

  • Coordinates with A3 artery and V3 vein as part of the segmental unit

  • Provides a bronchoscopic landmark during diagnostic bronchoscopy and biopsy

  • Guides surgical resection (segmentectomy/lobectomy)

Tributaries

  • Receives multiple subsegmental bronchi (B3a, B3b, B3c) that ventilate the anterior segment

MRI Appearance

T1-weighted images:

  • B3 lumen appears as a low-signal tubular structure; adjacent fat planes and vessels help localization

  • Limited routine visualization, best with high-resolution or 3D techniques

T2-weighted images:

  • Air-filled B3 lumen appears as a signal void (black) with hyperintense surrounding lung parenchyma

  • Mucus impaction or pathology may appear hyperintense within the bronchus

T2 TRUFISP (cardiac/respiratory-gated):

  • Provides bright fluid-tissue contrast; demonstrates airway caliber and dynamic motion

  • Helpful for assessing airway narrowing, obstruction, or extrinsic compression

STIR (Short Tau Inversion Recovery):

  • Fat suppression enhances delineation of peribronchial structures

  • Peribronchial edema or inflammation appears hyperintense

T1 Post-Contrast (Gadolinium-enhanced MRI):

  • Enhances peribronchial soft tissues rather than bronchial lumen (air-filled)

  • Useful for identifying peribronchial tumor, vascular invasion, or inflammatory changes

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

  • Demonstrates bronchial tree in 3D reconstructions

  • B3 is seen branching anteriorly from the right upper lobe bronchus, supplying the anterior segment (S3)

  • Valuable for pre-operative airway mapping and congenital anomaly assessment

CT Appearance

CT Pulmonary/High-Resolution CT (HRCT):

  • Best modality for direct visualization of B3 and its subsegments

  • Shows B3 branching anteriorly, coursing toward the anterior chest wall

  • Detects bronchial narrowing, obstruction, stenosis, or bronchiectasis

CT Coronary Angiography (CCTA) / CT Chest with 3D reconstructions:

  • Provides detailed visualization of B3 in relation to A3 artery and V3 vein

  • 3D bronchographic views help surgical planning for segmentectomy/lobectomy

  • Differentiates airway lesions, extrinsic compression, or congenital anomalies

CT images

Anterior segmental bronchus of right lung anatomy CT coronal image -img-00000-00000

CT images

Anterior segmental bronchus of right lung anatomy CT coronal image -img-00000-00000_00001