A spinal disc herniation (prolapsus disci intervertebralis), informally and misleadingly called a "slipped disc", is a medical condition affecting the spine due to trauma, lifting injuries, or idiopathic, in which a tear in the outer, fibrous ring (annulus fibrosus) of an intervertebral disc (discus intervertebralis) allows the soft, central portion (nucleus pulposus) to bulge out. Tears are almost always postero-lateral in nature owing to the presence of the posterior longitudinal ligament in the spinal canal. This tear in the disc ring may result in the release of inflammatory chemical mediators which may directly cause severe pain, even in the absence of nerve root compression (see pathophysiology below). This is the rationale for the use of anti-inflammatory treatments for pain associated with disc herniation, protrusion, bulge, or disc tear.
It is normally a further development of a previously existing disc protrusion, a condition in which the outermost layers of the annulus fibrosus are still intact, but can bulge when the disc is under pressure.
herniate Abnormal protrusion of an organ or other body structure through a defect or natural opening in a covering membrane, muscle or bone. See also hernia and individual anatomical sites for hernia.herniate[her・ni・ate]
- 発音記号[hə'ːrnièit]
- furthest from the centre."the outermost layer of the earth"
- the one that is furthest from the centre."the orbit of the outermost of these eight planets"
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