Left Coronary Artery ΓÇö Origin, Course, and Branches
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Left Coronary Artery — Origin, Course, and Branches
The left coronary artery (LCA) is larger than the right coronary artery. It arises from the ascending aorta and runs on the surface of the heart within the subpericardial fibrofatty tissue. It is shorter than the RCA before dividing into its two main branches.
Origin
Arises from the left posterior aortic sinus (left aortic sinus) of the ascending aorta, immediately above the aortic valve.
N.B. No coronary artery arises from the right posterior aortic sinus — this is termed the non-coronary sinus.
Course
Segment
Description
Initial
Runs forwards and to the left between the pulmonary trunk and the left auricle
Division
Emerges on the surface and divides into two main branches: the anterior interventricular artery and the circumflex artery
Main Branches
1. Anterior Interventricular Artery (AIV) — also called Left Anterior Descending (LAD)
Feature
Detail
Course
Descends in the anterior interventricular sulcus towards the apex
Termination
Winds around the apex and anastomoses with the posterior interventricular branch of the RCA in the posterior interventricular sulcus
Supplies
Both ventricles and the anterosuperior part of the interventricular septum
2. Circumflex Artery
Feature
Detail
Course
Curves postero-inferiorly with the great cardiac vein in the left anterior coronary sulcus, winds around the left border, continues in the left posterior coronary sulcus
Termination
Ends to the left of the posterior interventricular sulcus; anastomoses with the RCA at the crux (in right-dominant hearts)
Supplies
Left atrium and left ventricle; gives a left marginal branch to the left (obtuse) margin
Additional Branches
Branch
Notes
Left marginal artery
Branch of circumflex; supplies the left margin of the left ventricle up to the apex
Diagonal artery
May arise from the trunk of the LCA or from the AIV; supplies the anterolateral wall of the left ventricle
