The Junction Between the Left Atrium and the Pulmonary Veins

Abstract

Some anatomic features of the posterior wall of the left atrium, the atrial-pulmonary venous junctions, and the myocardial sleeves extending over the pulmonary veins, as observed in 16 human hearts, are described. Different patterns of direction of the myocardial fibers of the atrial wall were found in the different specimens. The atrial wall between the upper pulmonary veins was consistently thicker than that between the lower ones. Similarly, the sphincter-like structures of the atrial-pulmonary venous junctions were generally more conspicuous, and the myocardial venous sleeves better developed in the superior than in the inferior pulmonary veins. The physiological and pathological implications of these findings are discussed.