The brachial plexus and its branches provide the innervation of the upper limb.

The brachial plexus is formed by merging of the anterior rami of the fifth through eighth cervical spinal nerves (C5 - C8) and a large part of the anterior ramus of the first thoracic spinal nerve (T1).

In the neck, it is located in the interscalene space (between the anterior and middle scalene muscles).

Topographically, the brachial plexus can be divided in two parts:

• Above the clavicle - the supraclavicular part;
• Below - the infraclavicular part.