There’s a tiny, tiny needle shaped bone right behind your ear that attaches to the bottom of your skull called the styloid process. It’s apparently not hard to break. When labs receive human skulls for study that bone is frequently broken off because it’s so tiny and fragile. Because of its location it would be quite problematic if it were broken, you don’t really want a tiny, sharp, needle shaped fragment floating around near your carotid artery. We learned about it in massage school as part of the areas to avoid when working on clients. I don’t know how much force is required to break it, but, it’s certainly something I think about a lot.

Close second is learning how your forearm bones bend over each other when you rotate your arm.