This issue has come up in Question 14.3from the first paper of 2013. The candidates were invited to differentiate between an ulnar nerve injury and a lower brachial plexus injury in a patient who had returned from cardiac surgery. The images and text content in included below for the purposes of rapid revision. However, as far as point-form summaries from an authoritative source are concerned, Wheeless' Textbook of Orthopaedics does it much better.