The ventral rami of spinal nerves c4 to t1 contribute fibers to the plexus.

The ventral rami of spinal nerves c4 to t1 contribute fibers to the brachial plexus. The brachial plexus is network of nerves (4 cervical nervs and one thoracic nerve) and nerve roots, that begins in the root of the neck. The function of the brachial plexus is cutaneous and muscular innervation of the entire upper limb. 

Bruh i don’t know the answer tbh but you can google it