Biewener A A
J Exp Biol. 1983 Mar;103:131-54. doi: 10.1242/jeb.103.1.131.
Peak stresses acting in limb bones should increase with increasing size if the forces acting on the bones increase in direct proportion to the animal's body weight. This is a direct consequence of the scaling of limb bone geometry over a wide range in size in mammals. In addition, recent work has shown that the material strength of bone is similar in large and small animals. If the assumptions in this analysis are correct, large animals would have a lower safety factor to failure than small animals. The purpose of this study was to measure peak stresses acting in the limb bones of small animals during locomotion and compare the results with similar measurements available for larger animals. Locomotory stresses acting in the fore and hindlimb bones of two rodents, the ground squirrel (Spermophilus tridecemlineatus) and chipmunk (Tamais striatus), were calculated using ground force recordings and measurements of limb position taken from high speed x-ray cine films. Peak (compressive) stresses calculated to act in the bones of these animals (-31 to -86 MN/m2) are similar in magnitude to those determined for much larger mammals. The more proximal bones of the fore and hindlimb, the humerus and femur, were found to develop stresses (-31 to -42 MN/m2) significantly lower than those acting in the more distal bones of each limb: the radius, ulna and tibia (-58 to -86 MN/m2). All of the long bones from both species, except their femora, were found to be loaded principally in bending. The caudal cortices of each bone developed a peak compressive stress, whereas the cranial cortices were loaded in tension. Various features of the musculo-skeletal organization and manner of locomotion of these rodents are considered to explain how animals of different size maintain a uniform safety factor to failure.
如果作用在骨骼上的力与动物体重成正比增加，那么肢体骨骼中的峰值应力应随体型增大而增加。这是哺乳动物肢体骨骼几何形状在很大尺寸范围内缩放的直接结果。此外，最近的研究表明，大型和小型动物的骨骼材料强度相似。如果该分析中的假设正确，那么大型动物的失效安全系数将低于小型动物。本研究的目的是测量小动物在运动过程中肢体骨骼中的峰值应力，并将结果与大型动物的类似测量结果进行比较。利用地面力记录和从高速X射线电影胶片获取的肢体位置测量数据，计算了两种啮齿动物——地松鼠（Spermophilus tridecemlineatus）和花栗鼠（Tamais striatus）前肢和后肢骨骼中的运动应力。计算得出作用在这些动物骨骼上的峰值（压缩）应力（-31至-86 MN/m²）与在大得多的哺乳动物中测定的应力大小相似。发现前肢和后肢近端的骨骼，即肱骨和股骨，所承受的应力（-31至-42 MN/m²）明显低于每个肢体远端骨骼所承受的应力：桡骨、尺骨和胫骨（-58至-86 MN/m²）。除股骨外，这两个物种的所有长骨主要承受弯曲载荷。每根骨头的尾侧皮质产生峰值压缩应力，而头侧皮质承受拉伸载荷。考虑了这些啮齿动物肌肉骨骼组织的各种特征和运动方式，以解释不同体型的动物如何维持统一的失效安全系数。
