Here is a diagram showing the coronary arteries.

Important related facts to remember:

• LAD (left anterior descending) comes off left coronary - LAD is blocked in anterior infarctions
• LCX (left circumflex) comes off left coronary and the left marginal artery comes off the LCX - LCX is blocked in lateral infarctions and some posterior (if left dominant)
• Right coronary artery supplies the entire right side of the heart and gives rise to the right marginal artery - RCA is blocked in most posterior infarctions and infarctions affecting the right ventricle
• Which artery gives rise to the posterior descending artery determines the "dominance" of the heart - PDA from the RCA is right dominant [right dominant is most common], PDA from the left circumflex is left dominant

Also found FA2020 p283