Check out a pack of 174 Alpha masks of human bones by Dan Rozanski. All alpha masks are in 2048 resolution (PSD and TIFF formats). The set includes all basic human bones in various positions and angles, like Cranium, Femur, Humerus, Spine, Pelvis and much more.
The masks are said to be tested with Zbrush, Quixel, Substance, Blender and Mudbox.
All alpha masks in this pack can be used for commercial projects, by one person. You cannot repack and resell the masks.