One important reason for the significance of the thoracolumbar junction is that there are sudden changes in the structure of the joints that occurs in the territory of a single vertebra (T12): while the articular processes above this point is of the thoracic spine, those below it has the shape and mechanical features of bone lumbar back. During walking in place, the thoracolumbar junction acts as a fixed point, where the scoliosis of the lumbar spine to one side to the change of scoliosis of the thoracic spine to the opposite side.
Anatomist’s view ‘that the trunk rotation occurs mainly in the thoracolumbar junction was denied by Singer & Giles (1990). They demonstrated directly through the CT during the rotation of shaft rotation that occurs in this segment is almost no greater than that in neighboring segments of thoracic and lumbar motion. We confirmed these findings using trunk rotation AP film taken in a sitting position with the pelvis fixed. We show that scoliosis with rotation occurs in the whole lumbar spine.
Another transition region dysfunction is a common site to the T3/T4 cervicothoracic junction, this is where the movement of the head and neck end, as is most clearly seen in the ante-and retroflexion. The same goes for sidebending and rotation, although it is clear only in an upright position. One possible reason for the frequency of dysfunction in this region may be that it is a transition point between the most mobile part of the spine and the most mobile. Another is that this is the site where strong muscles and tendons of the upper limbs have their origin.