The spinal cord is surrounded by three layers of protective membranes called meninges.
Of the three sets of membranes protecting the brain and spinal cord, the outermost is
called dura mater.
Epidural spaceYou may have heard doctors giving epidural injections to relieve back pain or as an
anesthetic before surgery. “Epi” means outside and “dural” refers to the dura mater.
Thus, an epidural injection is given outside the dura mater and affects only the nerve
roots coming out from the spinal cord in order to block the sensation of pain.
Intervertebral foramina
Spinal nerves come out through spaces between the vertebrae called intervertebral
foramina (singular – foramen). A foramen is the medical term for a hole. Each nerve
root passes from the spinal column to other parts of the body through these small
openings, bounded on one side by the disc and on the other by the facets.