hi friend
your discription gives a picture likely of root level injury of brachial plexus.in traumatic injuries of brachial plexus,it wont follow a specific pattern.as suggested by others a detailed evaluation of cervical and thoracic spine should be done.also check for the sensation and tenderness in periscapular region,mmt of scapular muscles.
neural assessment should follow the pattern of
root level
trunk level
cord level
peripheral nerve level

please let us know the details of the same,cheers