Figure 3
From: Quantifying intervertebral disc mechanics: a new definition of the neutral zone
Sketch of the experimental set-up for four-point bending. The spinal motion segment (black) is embedded in the segment holder. Each vertebral body is provided with a jib holding three sonic crystals each. For communication, the crystals are submerged in a water bath. Bending forces Fb are applied by a materials testing device (not shown) and the segment holders rotate around rotation points R. Axial compression can be applied by a hydraulic force Fax.