This diagram came from an article called “Anomalous Origin of Left Coronary Artery” by John C. Ruddock, a Naval Reserve Medical Corps commander, and Charles C. Stehly, a US Army Medical Corps captain, published in Vol. 41 of United States Naval Medical Bulletin.
Ruddock and Stehly were trying to find out why a healthy-seeming 30-year-old suddenly died in the middle of his workday. It turned out his left coronary artery branched off (or “arose from”) the pulmonary artery in a way that most experts thought would be “incompatible with life.” Medical pros would expect someone born this way to die as an infant, with part of the heart muscle starved of oxygen and calcified. In this case, the artery maintained enough heart musculature to keep the whole heart going for years.
I found the diagram in the US Navy Bureau of Medicine and Surgery Office of Medical History Collection on archive.org.