Orientation of the Intercostal Muscle Fibers in the Human Rib Cage

Abstract

Great improvement was achieved to protect vehicle occupants in case of a motor vehicle crashes thanks to the development of restraint systems such as seat belts and airbags . These systems increase the mechanical coupling between the human body and the vehicle to minimize the risk of severe injuries to the thorax and the head during a crash. As a result, they may induce injuries, such as rib fractures because of the loading applied to the thorax by the seat belt. Predict- ing and preventing injuries to the thorax is of particular interest as severe injuries occurred predominantly in the thorax in side impact (Welsh et al. 2009) and in elderly subjects. Significant efforts were put in the development of computational finite element models of the thorax to accurately predict the rib fractures created because of an impact (Li et al. 2010). While the mechanical response of the individual human ribs has been widely studied (Charpail et al. 2005; Kindig 2009), only few studies reported on the contribution of the inter- costal muscles (ICM) on the rib cage impact response (Vezin & Berthet 2009). Furthermore, computational studies designed to assess the con- tribution of the ICM in the thorax impact response had to face the lack of detailed description of the ICM structure such as their thickness, and their fiber orientation (Poulard & Subit 2015). Therefore, the goal of this study was to measure the orientation of the fibers in the ICM layers in the human thorax .