Medial basal segmental bronchus of right lung

The medial basal segmental bronchus of the right lung (B7; Bronchus cardiacus pulmonis dextri) is the segmental bronchus that arises from the basal trunk of the right lower lobe bronchus and supplies the medial basal segment (S7) of the right inferior lobe.

Anatomical details:

• Origin: B7 typically branches from the basal trunk (also called the basal segmental bronchus) of the right inferior lobe bronchus, after the superior segmental bronchus (B6) has already taken off. It is usually the first branch of the basal trunk, arising from its medial aspect.

• Course and territory: It courses anteromedially and inferiorly toward the mediastinal surface of the right lower lobe, aerating the medial basal segment (S7), which lies adjacent to the mediastinum, the heart, and the diaphragm.

• Relationship to other basal bronchi: The remaining basal segmental bronchi of the right lower lobe include the anterior basal (B8), lateral basal (B9), and posterior basal (B10). The most common branching pattern of the right lower lobe is B6, B7, B8, B9, B10, found in approximately 57% of individuals.

• Variations: B7 may form a common trunk with B8 (the anterior basal bronchus) or, less commonly, with the subsuperior bronchus (B*). In some anatomic variants, B9 and B10 share a common trunk while B7 and B8 branch separately, or B7 may arise at a higher level from the basal trunk. Approximately 18% of individuals show a pattern where B9 is absent as a separate branch, with B7, B8, and B10 arising independently.