Herniated Intervertebral Disc
Hernia is the protrusion of an organ or part of an organ or other structure through the wall of the cavity that normally contains it.
Hernias are qualified by the name of the part that protrudes or the area through which protrusion occurs. Thus, an intervertebral disc hernia, known as herniated disc, covers the various permutations of disc material displaced beyond the intervertebral disc space.
Herniated discs are most common in people in their 30s and 40s, although middle aged and older people are slightly more at-risk if they are involved in strenuous physical activity.
Disc herniation occurs in the lumbar spine 15 times more often than in the cervical portion of the spine. Disc herniations in the cervical portion account for about 8% of the total. Only 1 to 2% of the intervertebral disc herniations occur in the thoracic (upper-to-mid-back) spine region.
Mostly, discs herniate because of injury or improper lifting.
However, degenerative process also plays a vital role in discs herniations because the intervertebral discs lose their flexibility, elasticity, and shock absorbing characteristics. The tough layer of ligaments that surround the intervertebral disc may weaken, and it may no longer be able to contain the gel-like substance in the center. This material may bulge or push out through a tear in the disc wall, causing pain when it touches a nerve.
(GlobalSpine.com)