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Background and Aims Nerve injury during brachial plexus blocks remains a significant challenge in regional anesthesia. This study utilizes Finite Element Analysis (FEA) to simulate the biomechanical and electrical interactions between needles and tissues, emphasizing the role of tissue dynamics in reducing nerve injury risks.Methods A 3D FEA model was developed using FreeFEM, incorporating MRI-based anatomical structures of muscle, adipose tissue, and nerves. Electrical properties were assigned based on literature values (muscle conductivity: 0.93 S/m, permittivity: 75; fat conductivity: 0.06 S/m, permittivity: 10). An 18-gauge stimulation needle was simulated under varying insertion angles (30°–90°), depths (2–6 cm), and pressures (5–20 psi). Mesh refinement ensured accurate stress and electric field distribution analysis.Results Simulations demonstrated that muscle tissue’s higher conductivity reduced the stimulation radius compared to adipose tissue. Optimal insertion angles (45°–65°) minimized nerve stress, while pressures above 15 psi increased nerve injury risk. Tissue boundaries significantly altered electric field distribution, affecting nerve activation thresholds.Conclusions FEA provides a robust framework for optimizing brachial plexus blocks by considering tissue dynamics and electrical properties. This approach enhances procedural safety, reduces nerve injury risks, and offers valuable insights for training and clinical application.