Abstract: A spinal jack adapted for installation between first and second vertebral processes, including a three dimensional and arcuate ergonomic main body constructed from first lower and second upper subset body portions, from which is displaceable an upper body between retracted and expanded positions. Each of the jack halves further includes gripping portions adapted for engaging the vertebral processes and preventing detachment following implantation. A worm gear mechanism is provided for expanding or retracting the jack halves in order to establish a corrected adjusted orientation between the processes.