At the level of the first rib, the lower cervical nerve roots combine to form the 3 trunks of the brachial plexus. The lowest trunk is formed by the union of C8 and T1, and this trunk lies ...

The condition affects primarily the upper trunk of the brachial plexus, which is part of the nerves that extend to the arms. These nerves are responsible for the muscular function and sensation of ...