it's like a tube of toothpaste squeezed from bottom to top. there's muscle around both the stomach and the whole length of the esophagus. same muscles ensure food makes it all the way down when swallowed.
Why do they assume the neck would be stiff and extended, when most animals curl up when vomiting? That's just unnecessary strain on already unwell body
I think it's some kind of suspension bridge thing, where a relatively inflexible neck is the only way it's muscles can support the silly thing at all. Idk though, this is like half of a memory from long ago.