Brachial plexus injury (BPI) is a severe nerve trauma that often leads to profound motor deficits and disability, including systematic pain. Among affected nerves, the musculocutaneous nerve is crucial for elbow flexion through the biceps brachii, a fundamental function for performing routine tasks. Nerve transfer has become an effective surgical technique to restore motor function by rerouting axons from intact donor nerves directly to injured targets, reducing regeneration time and distance. Despite its clinical use, recovery variability remains high, and detailed understanding of neuromuscular adaptations after surgery is limited. This thesis investigates motor control recovery in patients who underwent motor nerve transfer, combining force measurements with high-density surface electromyography (HD-sEMG) of the biceps brachii.