Figure 19: CA anatomy in CTGA. A The LCA arises from the right posterior sinus and gives rise to a large conus coronary artery (CC), the LAD, and a large diagonal branch (Diag). Usually the circumflex coronary arises from the LCA but is absent in this case. Cardiac veins are seen paralleling the CAs. B Left lateral view showing the origin of the RCA from the left posterior sinus. The sinus node artery (SN) arises from the RCA in this case instead of the LCx which is absent. C The LCA ostium is just above the right posterior sinus and the RCA ostium is in the left posterior sinus. The anterior leftward sinus is the non-coronary sinus.