The goal is to further investigate the cerebrovascular hemodynamic consequences of cervical spine positions, including rotation and manipulation in-vivo under clinically relevant circumstances using two advanced forms of MRI technology on the VA and posterior cerebral vessels. According to the knowledge of the investigators, a study utilizing MRI and functional blood oxygen level dependent (fBOLD) imaging to examine blood flow and perfusion, turbulence and evidence of micro-trauma within these vessels has yet to be conducted.