Anatomic relationship of the left atrium (LA). Posterior, right lateral, superior, and three-chamber view of volume rendered CT angiographies are shown. The LA (in blue) is located superiorly and posteriorly to the heart. The walls of LA include the anterior, superior, left lateral, septal, and posterior. Its superior (S) and posterior (P) walls are shown by double-headed arrows. Note close relation of the anterior (A) wall to the ascending aorta (AA). The left atrial appendage (LAA) is shown in yellow and the pulmonary veins are shown in red. The four pulmonary veins include LS = left superior, LI = left inferior, RS = right superior, RI = right inferior, LV = left ventricle.
