The brachial plexus are nerves that leave the cervical vertebrae (but originate in the brain) and extend to peripheral structures (muscles/organs) to transmit motor and sensory nerve impulses.
The Brachial Plexus is the nerve plexus from which supplies the upper limb. Its root supply is C5 to T1. This means that the nerves which make it up leave the spinal chord at all the vertebrae...