Fig. 7.  Paramedian sagittal oblique view of the L5–S1 junction and corresponding computed tomography image (bone window). The sacrum is recognizable as a horizontal hyperechoic curvilinear structure, and the L5 lamina has the typical “sawtooth” appearance. The structures of the vertebral canal are visible through the intervening gap. A distinguishing feature of the L5 lamina is its shorter superior-inferior width compared with the other lumbar vertebrae. (Image used with permission from www.usra.ca.)