Opening of right superior pulmonary vein

The opening of the right superior pulmonary vein refers to the ostium (opening) where the right superior pulmonary vein connects to the left atrium. This vein drains oxygenated blood from the right upper lobe of the lung into the left atrium of the heart.

In normal anatomy, the right superior pulmonary vein has a mean ostial diameter of approximately 14.3 ± 2.9 mm and is located adjacent to the superior vena cava. The ostium-to-last-tributary distance (the distance from the opening to the closest branch point) averages 11.8 ± 4.0 mm. 

The vein typically drains the apical, anterior, and posterior segments of the right upper lobe.

However, anatomical variation is common. Only about 71% of individuals have the classic four-vein pattern (two left and two right pulmonary veins). Variations include a common right pulmonary vein trunk (where superior and inferior veins share a single ostium), additional middle right pulmonary veins (present in approximately 19% of cases), or anomalous drainage patterns where the right superior pulmonary vein drains into the superior vena cava rather than the left atrium.