Anatomy Atlas

Left coronary artery

Arteria coronaria sinistra
Also: Left main coronary artery · LMCA
ArteryHigh-yielddraftCardio

Short trunk from the left aortic sinus that divides into the anterior interventricular (LAD) and circumflex arteries, supplying most of the left ventricle.

Core anatomy

Location

Between the pulmonary trunk and the left auricle, in the left part of the coronary sulcus.

Origin

Left aortic sinus of the ascending aorta (above the left cusp of the aortic valve).

Course

A short trunk (about 1–2 cm) passing between the left auricle and the pulmonary trunk before dividing. verify

Branches
Supplies

Through its branches: most of the left ventricle, the anterior two-thirds of the interventricular septum, the left atrium, and part of the right ventricle near the anterior interventricular groove. In left-dominant hearts, also the posterior septum and inferior wall.

Termination

Bifurcates into the LAD and circumflex arteries.

Branches

Structures supplied

Mentioned in

Generated automatically from links in other entries.

Coronary arteries, anterior viewThe right coronary artery runs in the right atrioventricular groove and, in right dominance, gives the posterior interventricular artery. The left main divides into the anterior interventricular (LAD) artery in the anterior interventricular groove and the circumflex artery in the left atrioventricular groove.Right coronary(RCA)Right (acute) marginalLeft mainLAD(anterior interventricular)CircumflexDiagonalObtuse marginalPosterior interventricular (PDA)— dashed = posterior surfaceAortaPulmonary trunk
Coronary arteries (anterior view). Right-dominant pattern shown; dashed vessels run on the posterior/inferior surface. ECG territories: LAD → V1–V4 (anteroseptal); circumflex → I, aVL, V5–V6 (lateral); RCA → II, III, aVF (inferior).
Original schematic, created for this atlas.
Opened aortic root showing three semilunar cusps, aortic sinuses and coronary ostia
Origins of the coronary arteries from the aortic sinuses.
Henry Vandyke Carter, Gray's Anatomy of the Human Body, 20th ed. (1918), Fig. 497. Source · Public domain (Public domain in the US: published before January 1, 1931 (per Wikimedia Commons))

Clinical correlations

Left main coronary artery disease PANCE

Mechanism / lesion

Significant stenosis or occlusion of the left main trunk puts both the LAD and circumflex territories at risk.

Classic presentation

Extensive anterolateral ischemia. Acute occlusion often causes cardiogenic shock or sudden death. ECG may show ST elevation in aVR with widespread ST depression. Significant left main disease is an indication for revascularization (CABG or PCI). verify

High-yield PANCE pearls

  • Left main → LAD + circumflex; left main occlusion = most of the LV at risk.
  • Diffuse ST depression + ST elevation in aVR → consider left main or severe multivessel disease.
  • Left dominance: the posterior interventricular artery comes from the circumflex.

Imaging anatomy

CT

Coronary CT angiography and calcium scoring. CT shows anomalous origins (e.g. left main from the right sinus).

Ultrasound

Echo shows extensive anterior and lateral wall motion abnormalities and reduced ejection fraction.

Key views & landmarks
  • Invasive coronary angiography (RAO and LAO caudal "spider" view show the left main bifurcation)

Physical exam

Strength / function testing

Assess for cardiogenic shock (hypotension, cool extremities, altered mental status, pulmonary edema) in suspected left main occlusion.

Self-quiz

Q1.

The left coronary artery divides into which two branches?

Show answer

B

The short left main trunk bifurcates into the anterior interventricular (LAD) and circumflex arteries. Diagonals come from the LAD; obtuse marginals from the circumflex.

Q2.

A patient with crushing chest pain is hypotensive. The ECG shows ST depression in most leads with ST elevation in aVR. Which lesion should be suspected?

Show answer

B

Diffuse ST depression with ST elevation in aVR in an unstable patient suggests left main or severe three-vessel ischemia. This needs urgent angiography.

Q3.

From which aortic sinus does the left coronary artery arise?

Show answer

B

The left coronary artery arises from the left aortic sinus, the RCA from the right, and the posterior sinus has no coronary artery ("non-coronary cusp").

Q4.

The left coronary artery sometimes has a third branch arising between the LAD and circumflex. What is it called?

Show answer

C

A ramus intermedius arises between the LAD and circumflex in some hearts. The conus and acute marginal arteries are branches of the RCA.

Q5.

Where does the short left main coronary trunk run before it divides?

Show answer

D

The left coronary artery arises from the left aortic sinus and passes between the pulmonary trunk and the left auricle before dividing into the LAD and circumflex. The RCA passes between the right auricle and the pulmonary trunk.

Flashcards

See also