"Normal" (textbook) arterial blood supply is sometimes found in less than 30% of all cases for some arteries (such as the dorsal arteries of the foot), but occurs in over 95% for others. The deviation from normal can occur at an artery's origin, its topographical location, and the area it supplies. As opposed to "malformations" (which may negatively influence organ function under usual circumstances), "variations" usually become significant only when physicians have to do something. For instance, it makes no difference to the liver if it is fed by an aberrant hepatic artery, but if the physician wants to give selective arterial chemotherapy the variation becomes clinically important.
When it can, this book estimates the frequency of specific arterial whimsicalities and wondrously explains the embryologic origins. More importantly, it classifies this capriciousness using 540 clinically useful schematic blue drawings. The book makes it easy to look up virtually any arterial