A 23-year-old college student is admitted to the emergency department after jumping from a 50-foot waterfall. The MRI of his back reveals a lateral shift of the spinal cord to the left. Which of the following structures has most likely been torn to cause the deviation?

The denticulate ligaments are lateral extensions of pia mater between the dorsal and ventral roots of the spinal nerves that attach to the dura mater. These ligaments function to keep the spinal cord in the midline position. The posterior longitudinal ligament supports the posterior aspect of the vertebrae within the vertebral canal. The tentorium cere- belli is a layer of dura mater that supports the occipital lobes of the cerebral hemispheres and covers the cerebellum. The ligamentum flavum helps maintain upright posture by connecting the laminae of two adjacent vertebrae. The nuchal ligament is a thickening of the supraspinous ligaments extending from the C7 vertebra to the external occipital protuberance.