Does everyone have a ramus coronary artery?

No, not everyone has a ramus coronary artery. The ramus coronary artery is a branch of the right coronary artery that supplies blood to the atrioventricular node and the bundle of His. It is present in about 50-60% of the population. In the remaining 40-50%, the blood supply to the atrioventricular node and the bundle of His is provided by the left anterior descending artery or the posterior descending artery.