I wouldn't say so; "halsen" means "the throat", and "nakken" means "the neck". https://en.wikipedia.org/wiki/Throat https://www.sundhed.dk/borger/sygdomme-a-aa/oere-naese-hals/om-oere-naese-og-hals/halsen/
I too am confused with sidder. This is not even given as an option in the hover prompts, nor is it explained. How is one to know this is the correct term, as I also checked and the literal translation for Hvor sidder nakken is where is the neck, and not where is the back of the neck.