Clinical significance
Anything arising from the intervertebral disc may be termed discogenic in particular when referring to associated pain as discogenic pain. Herniation
A spinal disc herniation, commonly referred to as a slipped disc, can happen when unbalanced mechanical pressures substantially deform the anulus fibrosus, allowing part of the nucleus to obtrude. These events can occur during peak physical performance, during traumas, or as a result of chronic deterioration (typically accompanied with poor posture), and has been associated with a Propionbacterium acnes infection. Both the deformed anulus and the gel-like material of the nucleus pulposus can be forced laterally or posteriorly, distorting local muscle function and putting pressure on the nearby nerve. This can give symptoms typical of nerve root entrapment, which can vary between paresthesia, numbness, chronic and/or acute pain, either locally or along the dermatome served by the entrapped nerve, loss of muscle tone and decreased homeostatic performance. The disc is not physically slipped; it bulges, usually in just one direction. Another kind of herniation, of the nucleus pulposus, can happen as a result of the formation of Schmorls nodes on the intervertebral disc. This is referred to as vertical disc herniation. Degeneration
Before age 40, approximately 25% of people show evidence of disc degeneration at one or more levels. Beyond age 40, more than 60% of people show evidence of disc degeneration at one or more levels on magnetic resonance imaging (MRI). These degenerative changes are a normal part of the ageing process and do not correlate to pain.
Herniated discs are also found to have a higher degree of cellular senescence than non-herniated discs. In addition to scoliosis, which is the lateral S curvature of the spine, the fused vertebrae can also experience other abnormalities such as kyphosis (hunchback) which shows in old age, or lordosis (swayback), which is often present in pregnancy and obesity. Etymology
The Latin word anulus means "little ring"; it is the diminutive of anus ("ring"). The misspelling annulus is also common. Additional images
See also
Back pain
Degenerative disc disease
Spinal decompression
Lumbar spinal stenosis

References
External links

Intervertebral Discs
Spinal Disc Summary
Cross section image: pembody/body12a—Plastination Laboratory at the Medical University of Vienna