Where do they get the models who pose nude for medical anatomy textbooks?

Kels: Where do they get the models who pose nude for medical anatomy textbooks?
In a lot of college-level medically related textbooks like anatomy and physiology, or biology, there are photos of naked models in various diagrams. They are usually in a standing position completely nude or in some other anatomical pose with lines with descriptions pointing to various parts of the body to help people learn about the anatomy. What are their job titles, or where do they get them? Are they professional models, or are they volunteers of some sort?

Answers and Views:

Answer by Diane A
There are professional medical anatomical models, but if you a re thinking of this for a career, I wouldn’t bother to pursue this. All you need to one model, and many of those pictures have been reproduced for decades. So the need and the ability to work is very tiny.