This book is a monograph about brachial plexus palsy. Severe brachial plexus injuries are often caused by traffic accidents, especially motorcycle accidents. The intercostal nerve transfer to the musculocutaneous nerve is a standard treatment of choice in Japan to reconstruct elbow flexion for brachial plexus palsy with root avulsion. The functional conversion of the nerve transfer is described in detail, using electrophysiological and histochemical studies. This book focuses on birth-related brachial plexus palsy as well as the treatment of brachial plexus injuries in adults.