So I was browsing the web when I stumbled upon something I thought you guys would like: someone by the username of /u/Kahhunna on reddit has created (and kindly given me permission to post) a page detailing anatomy of a tiefling!
It’s always interesting when people give their impressions of monster anatomy, or in this case tiefling anatomy. Hopefully this can give you some interesting ideas for your races, or for setting a scene. (Like a Phrenology diagram drawn on a tiefling’s skull, and sitting on some wizard’s desk instead of a typical human skull.)
Stay creative, readers!