I haven't been able to find the source on this one, but believe it dates to the early 20th century or so. No layers or fold out parts, but with two horizontal fold lines, surely a fold out insert in a volume on human anatomy. I love his face, and his pose, looking like a swimmer with a circulatory system of a bathing suit and lozenge shaped tattoos!
16 1/2 x 8 7/8 and in very good, clean condition, lies flat. One small tear to upper left of paper incurred in handling, mended from the back with clear archival tape, very minor.