This document discusses neck pain after trauma, specifically a hangman's fracture or traumatic spondylolisthesis of the axis (C2 vertebra). It notes disruption of the spinolaminar line at C2 on C3, indicating a fracture of the pars interarticularis of C2. It provides details on the anatomy of C2 including that it is the only vertebra with a pars interarticularis and discusses the mechanism of injury for a hangman's fracture, typically forceful hyperextension of the already extended neck.