A 62-year-old man with a 15-year history of ankylosing spondylitis presents to the emergency department after a fall from standing height. He reports sudden-onset severe neck pain and bilateral upper limb weakness. Imaging reveals a fracture-dislocation at C5–C6 with retropulsion of bone into the spinal canal. On examination, he has preserved perianal sensation and voluntary anal contraction. Which of the following best describes the neurological injury pattern and predicts the most likely functional outcome?