Two anatomical characteristics at the supra-lateral arcuate ligament were depicted in the cross-section computerized tomography. There was an apposition zone between the quadratus lumborum and diaphragm (endothoracic fascia) at the supra-lateral arcuate ligament. Diaphragm and endothoracic fascia course towards the anterolateral margin of the vertebral body at the supra-lateral arcuate ligament, while the quadratus lumborum courses towards the facet joint or transverse processes of the vertebral body. This results in a triangular gap between the diaphragm (endothoracic fascia) and quadratus lumborum (the green triangle refers to the gap). This triangular gap opens on its basal side to the T12 paravertebral space.