Modeling musculoskeletal systems with branching structures: A case study with the auxiliary tendon of the caudofemoralis longus muscle in crocodilians

Abstract

The branching in the musculotendinous structures is crucial to control complex, nonlinear musculoskeletal systems in vertebrate bodies. Although common, their functional impact remains unclear. Here, we present a dynamical model of musculoskeletal networks that explicitly incorporates branching points as mass points, representing geometric constraints and internal force distribution. Applying this model to the crocodilian hindlimb with branching musculotendinous structures, we validate results against robotic and anatomical studies. We find that branching reduces required muscle force, enhances joint coordination, and enables stable standing and propulsion with minimal input. These insights can guide biomechanical research and bio-inspired robotic designs.