The human spine consists of a series of bones, called vertebra, that run from the skull to the pelvis. The vertebrae connect together at facet joints with each bone separated by cartilage discs filled with a gel-like substance. This structure provides stability and allows flexibility for movement forward, backward and side to side. The intervertebral discs act as shock absorbers, but injury or disc degeneration can cause the disc to bulge out beyond the vertebrae, a condition known as a herniated disc.
Spinal Regions
The way the vertebrae of the spine connect together forms a natural "s" shape with three curves that help the spine distribute body weight. These curves also help to divide the spine into four main regions: the cervical, thoracic, lumbar and sacral regions. The cervical region includes the vertebrae, numbered C1 to C7, in the uppermost portion of the spine in the neck. The thoracic region, vertebrae T1 to T12, lies in the chest, while the lumbar region, L1 to L5, connects the spine to the pelvis. The sacral region, located behind the pelvis, includes vertebrae S1 to which are fused together during fetal development, as described by the Cleveland Clinic.
Function
The cervical spine supports the weight of the head, approximately 10 lbs., according to the doctors at the Mayfield Clinic. The vertebra in this section of the spine allows the head to move forward and backward and from side to side. The disc between each vertebra provides cushion between the bones and prevents the bones from rubbing together.
Causes
A neck injury sustained from improper lifting or sudden jerky movements such as during a car accident can damage the disc causing the outer wall to rupture and the inner material to bulge out invading the space in the spinal canal. Aging also contributes to a herniated disc by weakening the disc wall which increases the risk of a tear or rupture.
Symptoms
When a disc in the cervical spine region herniates, ruptures or bulges, it can compress the nerves running through the spinal canal. Nerve compression in the cervical region can cause pain in the neck that radiates down the arm to the hand. The pain may increase when turning the head or bending the neck. In addition to pain, some patients experience numbness and tingling in the arm that leads to muscle weakness.
Diagnosis
To determine the source of the neck pain, doctors can perform one or more of several types of imaging studies to visualize the bones, discs and location of the damage. Magnetic resonance imaging, or MRI, utilizes high frequency radio waves and a magnetic field to produce detailed images of the soft tissues, which includes the discs, in the spine. An MRI can detect disc damage and nerve compression as well as abnormal bony growths and spinal cord tumors. A myelogram uses a dye with X-ray technology to produce pictures that reveal nerve compression, bony overgrowths or tumors. Computed tomography, known as a CT scan, uses X-ray beams to produce 2-D pictures of the spine that help to confirm which cervical disc is damaged.
