When does a snake's head become a tail?

Is there some dividing point between a snake’s head and a snake’s tail? Is the tail everything behind the head? Is the whole snake basically one big tail with a head at the front? Or does the tail begin mid-way through the body of the snake?

I believe the tail is everything past the genital opening, or whatever it is snakes have…

Snake bodies are full of organs, from the head to the tail. No organs in the tail. Or you could go looking for their genitals, as mentioned above. Some snakes have wee little vestigial hind legs too, just before the tail.

inside a snake

Anatomically/scientifically the tail is that part of the body after the vent/cloaca, which is the common urinary, faecal/genital outlet form the body.

In less refined terms the tail is the part after the arsehole.