Anatomy Question: Right-, Left-, Co-dominant circulation

Hi all, I'm having issues on "deciding what source to trust." The topic is left-, right-, and co-dominant circulation. Also, I'm a bit confused as to where the AV nodal artery, SA nodal artery, and PDA originate from. Question #1: What determines right-/left-/co-dominant circulation? Is it the PDA, or the AV Nodal Artery? Some sources (Lilly's Pathophysiology of Heart Disease 6E, USMLE First Aid 2017) say it's the PDA. In other words, if the PDA comes from the RCA --> right dominant, vice... Anatomy Question: Right-, Left-, Co-dominant circulation
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