ABSTRACT
Background: Human heart is supplied by coronary arteries – Right and Left coronary artery. The coronary arteriesarise from the aortic sinuses and the left coronary artery from the left posterior aortic sinus. The left coronaryartery has two branches, the anterior interventricular and circumflex arteries. The anterior interventricularbranch is the continuation of left coronary artery, gives off septal branches, right and left ventricular branches.The left ventricular branches are called diagonal arteries. The left circumflex artery gives off left atrial and leftventricular branches. One of these atrial branches supply the sinoatrial node in 35% of subjects and AV node in10-20% of the subjects.Materials and Methods: The study was carried out in the department of anatomy, Kasturba Medical College,Manipal, India. The study was performed on 50 formalin fixed human hearts of unknown sex and age. The leftcoronary artery and their branches were carefully dissected. The origin, branches & branching pattern of leftcoronary artery was observed, noted and photographed.Results: In present study, 49 samples (98%) showed the origin of left coronary artery from left posterior aorticsinus while 01 sample (02%) had no trunk of left coronary artery. Sino-atrial nodal artery was originating formcircumflex artery in 13 samples (26%) and atrio-ventricular nodal artery from the circumflex artery in 05samples (10%). The trunk of left coronary artery was bifurcating in 37 samples (74%) and trifurcating in 12samples (24%) with one sample (02%) showing absent trunk of left coronary artery. The median artery waspresent in 12 samples (24%) and posterior interventricular artery was originating from circumflex artery in 05samples (10%).Conclusion: Left coronary artery commonly originated from left posterior aortic sinus with very few variations.Sino-atrial nodal artery and atrioventricular nodal artery commonly originates from right coronary artery.Bifurcation of left coronary artery is commoner than trifurcation. The present study is useful in better understandingof the normal and variant anatomy of left coronary artery