Neuroanatomy USMLE Step 1 Practice Question

A 28-year-old woman presents to the neurology clinic with a 3-month history of progressive loss of pain and temperature sensation across her shoulders, upper arms, and upper back in a cape-like distribution. She reports no difficulty with fine touch discrimination on her fingertips or weakness in her arms. Physical examination confirms intact motor strength (5/5) throughout bilateral upper extremities, normal vibration and proprioception sense in the hands, but absent pain sensation to pinprick across the shoulders and upper arms bilaterally. Vital signs are stable. MRI of the cervical spine demonstrates a cavitating syrinx centered at the C4-C5 level with mild cord expansion. CSF analysis and culture are unremarkable. Which of the following spinal tracts is most likely compromised by this lesion?