Some drawings try to be as realistic or biologically accurate as possible and others take a lot of creative liberty. As an artist it is up to you to decide how you want your art to be. If you want to draw realistic and detailed bones then you may want to do some anatomy research. You may also want to have a vision in your mind of who is bones they are, that means people of different ages, genders, and weight may have differences in the visual appearances of their bones. If you are drawing a mouth or a skull then keep in mind the dental hygiene of the person when they were alive.
Some art classes in college may also have anatomy aspects. If you are a registered college student you may be able to access some free resources through your school to get some insight on what is anatomically correct.