Here’s an example of proper skull anatomy in a professional anime. I just wanted to provide this to illustrate how to properly draw an anime skull and to prove that anatomy in anime/manga is very real. It does exist, and this is how it looks.
As you can see, the teeth on the inside of the mouth and the jaw are actually much larger than people seem to think, despite the small appearance of the mouth on the outside. This is true in real human anatomy as well. The nasal cavity opening is also slightly higher than the tip of the nose. This is because the bridge of the nose is often downplayed on anime characters and the tip of the nose is mostly cartilage so it does not appear on the skull.
Hope this helps you skeleton drawers.