Synonyms
Medical: Discus intervertebralis English: discogenic intervertebral disc, intervertebral discs
Anatomy
The intervertebral discs (lat. Disci intervertebrales) form the flexible connection between all vertebrae, with which they are firmly fused. An exception is the articulated connection between the skull and the first cervical vertebra (atlas), as well as the first and second cervical vertebra (axis).
A total of 23 intervertebral discs are found in humans, which make up about a quarter of the total length of the spinal column. Each intervertebral disc can be divided into two components. An inner gelatinous core, the nucleus pulposus (usually simply called “nucleus”) and an outer fibrous ring (annulus fibrosus) surrounding it.
The latter consists of fibrous cartilage tissue with a high collagen content, giving it a firm, pressure-resistant and tough consistency. On closer inspection, it can be seen that it is made up of circularly arranged lamellae. The outermost lamellae radiate into the cover plates of the bony vertebral bodies, while the inner lamellae partially radiate into the gelatinous core of the intervertebral disc, so that the transition between the fascia ring and nucleus is rather blurred.
The gelatinous core, like the fibrous cartilage surrounding it, contains only a few cells. Instead of collagen, however, it consists mainly of long-chain sugars, the so-called glycosaminoglycans. These are characterised by a high water-binding capacity, so that the gelatinous core consists of up to 85% water.
This creates a swelling pressure inside the intervertebral disc, which puts the outer fibrous ring under tension. Only the interaction of both components gives the intervertebral discs their characteristic properties, which make them indispensable for the proper functioning of our spine. In everyday life, this construction is subjected to a constant stress test in the form of movements and impacts, which can, however, be effectively cushioned and passed on to the vertebrae by the structure described above.
Apart from this, the intervertebral discs must of course also continuously carry our body weight. This load naturally increases in the direction of the coccyx in standing and sitting. For this reason, both the vertebral bodies and the intervertebral discs between them increase in diameter steadily from the neck downwards. Nevertheless, by far the most herniated discs and other spinal diseases are found in the lumbar spine.
Function of the intervertebral discs
The intervertebral disc acts like a shock absorber due to the elastic gelatinous core. It elastically absorbs shocks. Furthermore, it can deform during movement due to its elastic properties. This is the basic prerequisite for the mobility of the spine.
Diseases of the intervertebral disc
In the course of life the intervertebral disc wears out. The fibrous ring becomes cracked. Due to the swelling pressure of the gelatinous core, it can leak.
The result is a herniated disc. A herniated disc does not necessarily lead to discomfort. Only when the herniated disc affects the spinal cord or nerves can chronic back pain, sensory disturbances or paralysis develop.
You can find detailed information on this topic at
- Slipped disc
- Chronic back pain
- Lumbar spinal syndrome
- Cervical Spine Syndrome
A preliminary stage of the herniated disc is the disc protrusion (protusio = protrusion). Here, the fibrous ring gives way due to wear and tear and bulges at the weakest point due to the swelling pressure of the gelatinous core. However, the fibrous ring is still intact and the gelatinous core has not yet protruded.
Nearly all people show a disc protrusion at an advanced age. Therefore, the protrusion should be considered a normal wear process. However, a protrusion can also indicate an imminent disc protrusion.
In addition to the removal of the intervertebral disc, an intervertebral disc prosthesis is increasingly being implanted. What significance the disc prosthesis will have in the future will become clear. Inflammation of the intervertebral discs is a very rare disease.
In the technical language it is called “disciitis”. Frequently, an inflammation of the vertebral body also occurs simultaneously. In this case, we speak of spondylodiscitis.
The causes of spondylodiscitis are manifold. In most cases, however, it is caused by an infection with bacteria, more rarely by viruses or fungi. The pathogens usually reach the area of the intervertebral discs as part of a surgical procedure or an injection.
In most cases, however, it is difficult to detect the pathogen, so that diagnosis is preferably made by imaging procedures such as magnetic resonance imaging (MRI), in combination with elevated levels of inflammation in the blood. The severity and course of an inflammation of the intervertebral discs usually varies greatly from individual to individual. Both completely asymptomatic courses, as well as severe pain and general symptoms such as fever, fatigue and chills are possible.
The most feared are neurological symptoms and neuropathic pain as a result of the infection spreading to the spinal nerves or spinal cord. If a purulent abscess forms in the spinal canal, in the worst case this can lead to the symptoms of paraplegia. The treatment of spondylodiscitis and also pure discitis in the case of a bacterial infection consists mainly of antibiotic therapy adapted to the pathogen.
In addition, an adequate drug therapy with anti-inflammatory painkillers is started according to the pain. It is also important to immobilize the affected spinal area for several weeks. A corset or orthosis can be used for this purpose.
Infections in the lumbar spine area usually require bed rest, since immobilization is hardly possible here. If the disease cannot be controlled in any other way, a surgical procedure must be performed to remove the abscess. The prognosis of an inflammation of the intervertebral disc is generally rather poor.
Although the disease is fatal in only a few cases. However, permanent neurological impairment, such as disturbances of sensitivity and motor function, are not rare. A recurrence, i.e. the recurrence of inflammation, occurs in about 7% of patients. View from above:
- Nucleus pulposus gelatinous nucleus
- Anulus fibrosus Fiber ring
- Slipped disc
View from above:
- Nucleus pulposus gelatinous nucleus
- Anulus fibrosus Fiber ring
- Slipped disc
