Department of Ecology and Evolutionary Biology, Brown University, 80 Waterman St. Box G-W, Providence, RI 02912, USA.
J R Soc Interface. 2012 Oct 7;9(75):2667-79. doi: 10.1098/rsif.2012.0153. Epub 2012 May 2.
Unlike mammalian, disc-shaped intervertebral joints (IVJs), the IVJs in fishes are biconid structures, filled with fluid and thought to act as hydrostatic hinge joints during swimming. However, it remains unclear which IVJ structures are dominant in mechanical resistance to forces in fishes, and whether variation in these tissues might impact the function of the vertebral column along its length. Here, we measured the dynamic mechanical behaviour of IVJs from striped bass, Morone saxatilis. During lateral bending, angular stiffness was significantly lower in the caudal and cervical regions, relative to the abdominal region. The neutral zone, defined as the range of motion (ROM) at bending moments less than 0.001 Nm, was longer in the caudal relative to the abdominal IVJs. Hysteresis was 30-40% in all regions, suggesting that IVJs may play a role in energy dissipation during swimming. Cutting the vertical septum had no statistically significant effect, but cutting the encapsulating tissues caused a sharp decline in angular stiffness and a substantial increase in ROM and hysteresis. We conclude that stiffness decreases and ROM increases from cranial to caudal in striped bass, and that the encapsulating tissues play a prominent role in mechanical variation along the length of the vertebral column.
与哺乳动物的盘状椎间关节 (IVJ) 不同，鱼类的 IVJ 是双锥形结构，充满液体，在游泳时被认为充当静压铰链关节。然而，目前尚不清楚哪种 IVJ 结构在鱼类的力的机械阻力中占主导地位，以及这些组织的变化是否会影响沿脊柱长度的功能。在这里，我们测量了条纹鲈鱼 Morone saxatilis 的 IVJ 的动态力学行为。在侧向弯曲时，相对于腹部区域，尾部和颈部区域的角刚度显着降低。中性区定义为弯曲力矩小于 0.001 Nm 时的运动范围 (ROM)，尾部 IVJ 的中性区比腹部的长。在所有区域，滞后都为 30-40%，这表明 IVJ 在游泳时可能在能量耗散中发挥作用。垂直隔膜的切割没有统计学上的显着影响，但封装组织的切割导致角刚度急剧下降，ROM 和滞后显著增加。我们得出的结论是，条纹鲈鱼的刚度从颅侧到尾侧减小，ROM 增大，并且封装组织在脊柱长度上的机械变化中起主要作用。
