Figure 5. Relevant Anatomy Surrounding the Left Atrial Appendage Illustration of the human heart showing the left atrial appendage (LAA) and its closely related structures. Notice that the tip of the appendage is pointing towards, as well as the body of the LAA, covering the left circumflex artery and great cardiac vein. Also seen is the overlying left phrenic nerve coursing on top of the LAA. The vein of Marshall traverses through the LAA and left superior pulmonary vein. The closely related pulmonary trunk also is shown abutting the LAA.