The spinal cord begins at the foramen magnum and ends at the lower border of L1, tapering (as nerve roots are given off) from the cervical enlargement to the conus medullaris at the end. The conus medullaris is attached by a stalk of pia mater, the filum terminale, to the end of the dural sac at S2. It also gives rise to the cauda equina, consisting of the roots of the spinal nerves from L2 to Co which pass caudal to the conus to exit at their respective intervertebral foramina.

The spinal cord and nerve roots are covered by three meningeal layers. Denticulate ligaments, bilateral thickenings of pia connecting to the dura, allow the spinal cord to float in the CSF. At each level and side, spinal nerve roots emerge from the ventral and dorsal aspects of the cord to form the anterior motor and posterior sensory roots. The two roots on each side join to form a mixed spinal nerve in the intervertebral foramen. Where the spinal roots unite, the meninges fuse with the epineurium of the spinal nerve.