Evolutionary aspects and muscular properties of the trunk-Implications for human low back pain

Because of minor macroscopic differences between humans and other mammals, and even primates, we started to take a closer look at the paravertebral musculature. A three-dimensional investigation of muscle's fibre type distribution was undertaken on laboratory rats. Serial sections from the caudal thoracic and lumbar regions of the back were analysed, and the fibre type distribution pattern in all paravertebral muscles was described. Comparisons to other species imply more general characters of the fibre type distribution in mammals. Established concepts of human back muscle function were exposed to be valid for quadruped mammals as well. Muscle properties predicted by a biomechanical model based on human's anatomy (Wagner et al., this issue) were confirmed by results of the current study on a small mammal. Therefore, we propose only minor differences from the observed pattern in human back muscles.