Origin and course
The left coronary artery originates from the aorta at the level of the left aortic sinus (sinus aortae sinister).
From its origin, the vessel courses to the left. It passes posterior to the root of the pulmonary trunk (truncus pulmonalis), lying between it and the left auricle (auricula sinistra). Having reached the left part of the coronary sulcus (sulcus coronarius), the main trunk of the artery divides into two branches.
What branches does the left coronary artery divide into?
The left coronary artery divides into two branches:
- Anterior interventricular branch (r. interventricularis anterior) is the continuation of the main trunk. It descends along the anterior interventricular sulcus, curves around the apex of the heart, and enters the terminal part of the posterior interventricular sulcus. Before reaching the posterior interventricular branch, it plunges into the myocardium. It gives off interventricular septal branches (rr. interventriculares septales), the branch of the arterial cone (r. coni arteriosi), branches to the anterior part of the interventricular septum, diagonal lateral branch (r. lateralis) to the anterior wall of the left ventricle, and anastomotic twigs to the branches of the right coronary artery. It fully supplies the apex of the heart.
- Circumflex branch (r. circumflexus) — emerges from beneath the left auricle, runs along the coronary sulcus to the pulmonary (lateral) surface, then passes to the diaphragmatic surface. At the transition to the diaphragmatic surface it gives off a large posterior branch of the left ventricle (r. posterior ventriculi sinistri) to the anterior and posterior walls of the left ventricle. Left marginal branch (r. marginalis sinister) runs inferiorly and posteriorly along the pulmonary surface to the apex.
Lymphatic drainage along the artery
The lymphatic vessels of the heart are divided into deep and superficial. The deep vessels originate from the capillaries of the myocardium and endocardium, while the superficial ones begin in the capillary networks of the epicardium.
The drainage pathways accompany the coronary arteries. The left pathway runs along the a. coronaria sinistra: the vessels converge, pass along the posterior wall of the pulmonary trunk, and drain into the tracheobronchial nodes at the tracheal bifurcation.
Clinical significance
Coronary arteries are essential for understanding the topical diagnostics of myocardial infarction.
The excerpts use the following abbreviations:
- LCA — left coronary artery;
- AIA — anterior interventricular artery;
- Cx — circumflex artery;
- LAD — left anterior descending artery;
- MI — myocardial infarction;
- NSTEMI — non-ST-segment elevation myocardial infarction.
In stable coronary artery disease, the choice of revascularization is considered between CABG — coronary artery bypass grafting — and PCI — percutaneous coronary intervention.
Class and exam questions
Where does the left coronary artery arise from?
It originates from the aorta at the level of the left aortic sinus.
What branches does the left coronary artery divide into?
It divides into the anterior interventricular branch and the circumflex branch.
Where does lymph drain via the vessels accompanying this artery?
The lymphatic vessels of the left pathway, running along the left coronary artery, drain into the tracheobronchial nodes at the bifurcation of the trachea.
What else to study on this topic
- Right coronary artery
- Ascending aorta
- Coronary sulcus of the heart
- Lymphatic system of the heart
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