While marker-based motion capture readily provides detailed assessment of the lower limbs, the spine has been overlooked. Conventional clinical gait models treat the trunk as a single rigid segment and cannot examine the interactions between the lumbar, lower thoracic, and upper thoracic regions. However, evidence clearly demonstrates inter-segmental mobility of the spine. We utilize 3D marker clusters placed on the back to track the complex tri-planar motions of each spinal region. This structured approach provides clinically relevant data on coordination between the pelvis, lumbar, lower thoracic, and upper thoracic segments in all planes of movement. Our methodology highlights the need to report global movement patterns when analysing relative motions between segments. Standardizing 3D cluster design, construction, and implementation remains an important goal for the field. Overall, our research aims to further understanding of multi-segment spinal kinematics during gait. This knowledge can improve clinical assessment and treatment of gait impairments related to spinal pathologies or injuries.