The brachial plexus is an anatomical grouping of nerve networks formed by the union of the ventral roots of the spinal nerves in the cervical and thoracic regions. It is a structure about 15 cm long, starting proximally from the musculus (m.) scalenus and continuing distally to the fossa axillaris. The anterior branches of the C5-T1 spinal nerve roots merge to form the truncus, the truncus divides into anterior and posterior branches to form the fasciculus, and the fasciculus merge in various ways to form the terminal branches. This division allows nerves to be directed to different muscles and dermatome areas. As it continues towards the periphery, it gives its terminal branches at the shoulder level. The plexus brachialis is responsible for motor and sensory innervation of the upper extremities. Clinically, plexus brachialis lesions can lead to serious losses in upper extremity functions. Traumas, traffic accidents, fractures and shoulder injuries, especially during childbirth, cause damage to the plexus brachialis. In addition, specific clinical pictures (such as Erb-Duchenne paralysis, Klumpke paralysis) may develop due to damage to specific branches of the plexus brachialis. These lesions severely limit the daily activities of patients. Injuries to the plexus brachialis can lead to permanent loss of function if left untreated. Early diagnosis, physical therapy and surgical intervention play an important role in such injuries. Knowing the correct anatomical structure of the plexus brachialis and evaluating the variations is of great importance especially in cases of trauma for diagnosis, selection of appropriate treatment methods and effective nerve blockage when necessary.