If you want to get real, there’s the Vesalius Project, 3D photographic quality color models of anatomical (sub)structures, obtained from the Visible Human Data sets. Visible Human? You know how some days you feel strained? The (USA) National Library of Medicine has developed the Visible Human Project®. They’ve scanned complete, anatomically detailed, three-dimensional representations of the normal male and female human bodies. The male was sectioned at one millimeter intervals, the female at one-third of a millimeter intervals. That’s strained.
There’s now no excuse for not having beautiful drawings of the human form that you, yourself, have made.