CT Pulmonary Angiography > PA Anatomy > Right Lung > Right Middle Lobe

PA Anatomy: Right Middle Lobe

The right middle lobe has lateral and medial segments, which by definition have pulmonary arterial supply from A4 and A5, respectively. In approximately one-half of individuals, A4 and A5 arise as separate branches from the anteromedial aspect of the interlobar artery, and in the other one-half of individuals they arise as a common trunk at this location before dividing (6). Uncommonly, three separate trunks are seen (7-8). Either A4 or A5 may have a common origin with a lower lobe segmental artery, however (9). A branch of the medial segmental artery may cross segmental boundaries and also supply the anterior aspect of the lateral segment (11).

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