Lateral vein of right lung

The lateral vein of right lung (V4; lateral part of the middle lobe vein) drains the lateral segment (S4) of the right middle lobe. This vein typically has a diameter of approximately 4.1 ± 1.6 mm and shows variable drainage patterns with the medial vein of right lung.

• In 53.3% of cases, the medial and lateral parts unite to form a middle lobe vein trunk that drains into the right superior pulmonary vein

• In 16.6% of cases, the medial and lateral parts drain separately into the right superior pulmonary vein

• Other variations include drainage into the left atrium directly or into the right inferior pulmonary vein.