Understanding Your Spine

The spine is made up of four sections—cervical (neck); thoracic (bottom of neck to top of low back); lumbar (lower back); and sacrum (the fused levels of bone below the waist).  At the very bottom of the sacrum is the coccyx, familiarly known as the “tailbone.”  The vertebrae of each section are numbered, such as C-4 for the fourth vertebra down from the skull or L-5 for the last vertebra before the sacrum.

In between the vertebral bodies are the discs, which hold the vertebrae together, absorb shock and act as pivot points allowing the spine to rotate and bend.  Discs are comprised of the annulus fibrosus (the outer “container” part of the disc) and nucleus pulposus (the fluid inner part of the disk).  These disks are named by the vertebral bodies above and below it, such as L5-S1, which is the disk between the bottom lumbar vertebra and the top sacral fuse bone section.  The sacrum is the only part of the spine that does not have discs.

One spinal injury is an “annular tear,” meaning the outer “container” part of the disc has torn open, allowing the fluid from the disc to leak out.  Other, more commonly known, disc injuries include “bulge,” “herniation,” “protrusion,” and “extrusion.”  Though these names should reflect the severity of the disc coming out, they are frequently used interchangeably, often causing confusion.

The spinal cord runs down the back from the brain stem down to the sacrum.  The spinal cord is surrounded by the thecal sac (the outer “container” part) which contains cerebral spinal fluid.  If a disc protrudes, it can push on the thecal sac, which can cause the fluid to put pressure on the spinal cord.  Because the spinal cord branches out at each level of vertebral body and disc (called nerve roots), sometimes the pressure can be on the nerve root resulting in pain down the arm or leg. 

As our bodies age, it is common for discs to bulge, protrude, or even herniate, often without causing any pain.  We may never know this has happened because we have no symptoms.  However, if we experience trauma to our backs, such as, from a fall or an automobile collision, symptoms can occur—either from a newly injured disc or from a previously injured disc that didn’t cause pain until trauma “lit up” the pain.  It’s vital to consult with a doctor if pain radiating down the arms or legs is experienced or if ongoing back pain despite conservative treatment (massage, physical therapy, etc.) is experienced.  And if an injury caused the pain, consult with an experienced injury attorney.  Buckland & Schumm offers free initial consultations by phone or in person.

Adapted from an article by Jeff Davis in the May 2009 edition of Trial News.  Next month will focus on treatment of back pain.