The phrase "heads backward" is correct and usable in written English.
You can use it when you are describing the action of someone or something turning away or moving away from something. For example, "The snake suddenly heads backward into the grass."
As they stood in first position, a snap in their torsos sent their heads backward with a lurch.
But upon "death," players — I've taken an informal survey, here — tend to toss their heads backward and giggle riotously.
It was a moment of domestic tranquillity here in Cambodia's only shelter for acid burn victims, where a dozen other mutilated residents napped or sang or hung their heads backward in an exercise to help keep their scarred necks flexible.
Then, around 10 p.m., they hurried across the street to a centuries-old cathedral where they titled their heads backward, lifted their palms heavenward and rocked back and forth, in thrall to a religious ardor that most of Europe has lost.
For all their public popularity, flamingos turn out to be poorly understood scientifically, and only lately have researchers ventured answers to basic questions like why the birds spend so much time perched on one leg, and contort their heads backward before settling down for the night; how they keep their feathers so "Miami Vice" bright, and select a well-suited mate from the deafening throng.
Now it was time to head backward.
Meanwhile, gear changes snapped my head backward for all the wrong reasons.
Jets linebacker Marvin Jones grabbed them three weeks ago, jerking Williams's head backward in a sideline tackle.
It was constructed like a T-shirt pulled over the head backward, and it reminded me of late Balenciaga".
Raising her eyes, tipping her head backward, she had sensed more energy pouring into her from the sky.
In the fourth round, Khan ducked, then bounced Malignaggi's head backward with a powerful right hand.
