UC San Diego

Jerboas are fascinating rodents who are known for their striking athletic abilities. The highest recorded jerboa jump is more than ten times hip height, and they can run at speeds as high as 24 km/hr. The goal of my study is to deepen the understanding of the biomechanics of the hindlimb of such an incredible rodent. Previous biomechanical research by Dr. Moore’s group involved observing the jerboa in motion in a laboratory setting, followed by a two-dimensional inverse dynamic analysis using ground reaction forces to better understand jerboa hindlimb muscle contributions in terms of work produced during a vertical leap. However, muscles of the hindlimb of the jerboa have not been functionally classified yet. In this thesis, we aim to develop a more accurate three-dimensional model to investigate muscle functional roles. Through detailed segmentations of all the bones and muscles in a jerboa, an accurate OpenSim model with the entire endoskeleton consisting of the spine, skull, entire hindlimb and 32 muscles was developed. Conducting inverse dynamic analysis for different jerboa gait trials, we aim to find concrete evidence on how these fascinating rodents are able to achieve such high athletic abilities, especially in the case of vertical leaps. We aim to discuss and compare muscle groups based on their supposed functions. A sensitivity analysis was carried out on wrapping features and muscle attachment paths to validate muscle placements and biomechanical outputs. Finally, distinct muscle functions of the jerboa were compared to those of the quadrupedal rodent, mouse and a bipedal chimpanzee.