Upper-arm weakness (paresis) or paralysis indicates peripheral-nerve damage to the brachial plexus, a network of lower cervical and upper thoracic spinal nerves supplying the arm, forearm ...

About one in 1,000 children are born with brachial plexus birth injury (BPBI), upper extremity weakness or paralysis resulting from trauma to the brachial plexus nerves during childbirth.

[15] The posterior rami provide spine muscle and trunk skin sensation. The most complex nerve plexus is the brachial plexus, consisting of cervical nerves 5 through 8 (C5 to C8) and thoracic nerve ...