hyperextension.
Hyperextension is a extension of a limb, a joint or part of the body beyond the normal limit.This can be a good exercise that works the lower back, the mid and upper back, specifically the erector spinae that suport our spine.
Basically, this range of motion is how far in each direction that joint can bend comfortably.
Blood flows to the brain through the internal carotid and vertebral arteries and away from the brain through the internal jugular vein. The internal carotid artery supplies the brain, while the external carotid nourishes other portions of the head, such as the face, skull, scalp and the meninges. The vertebral arteries provide supply to the upper spinal cord, brainstem, cerebellum, and the posterior part of the brain.