Home > Spine > Spine Glossary > Spine Glossary - Thoracolumbar junction. Spine Glossary - Thoracolumbar junction. This is the junction between the Thoracic spine and the Lumbar spine. The junction consists of the part of the vertebral column from the eleventh thoracic vertebra to the first lumbar vertebra. Here the spinal curvature changes from kyphosis to lordosis, and the orientation of the facet joints changes from coronal to sagittal.