Before the age of photography, and before they got their cadavers, med students relied on beautiful layered drawings in books to see into the body. To illustrate body parts in classes, professors relied on large representations in the form of sculptures, 3-D XXL models.
Artists like Thomas Eakins worked with a surgeon named Keen to learn human anatomy in exacting detail. Art and medicine are still crossing paths today at many places. Yale medical school has a program wherein its med students are trained to enhance their observing powers at the Yale Center for British Art, by looking at a painting, then attempting to describe it to someone who hasn't seen it. This has proven to improve their skills at observing and communicating what they see over the decade it has been in effect.
Over twenty medical schools across the US have programs like this one.