Intervertebral symphysis. Structure, functions

Intervertebral symphysis , symphysis intervertebralis. Is represented by intervertebral discs (cartilages) lying between the bodies of two adjacent vertebrae throughout the cervical, thoracic and lumbar spine.

The intervertebral disk, discus intervertebralis, belongs to the group of fibrous cartilages. It distinguishes the peripheral part - the fibrous ring, anutus ftbrosus, and the centrally located gelatinous nucleus, nucleus pulposus.

In the orientation of collagen fibers forming a fibrous ring, three directions are distinguished: concentric, oblique and spiral.
All fibers are lost by their ends in the periosteum of the vertebral bodies.

The central part of the intervertebral disc - gelatinous nucleus - is very elastic and is a kind of springing layer, which, with the inclinations of the spine, is displaced towards the extension. On a section of the intervertebral disc, a gelatinous nucleus, squeezed under normal conditions, protrudes above the surface of the fibrous ring. The gelatinous nucleus may be continuous or have a small slit-like cavity.

The transition of the fibrous ring to the gelatinous nucleus is gradual. To the center of the disk, the amount of fibers in the intercellular substance decreases in its tissue, but the mass of the basic substance increases. Up to 20 years, the gelatinous nucleus is well expressed, and then, with age, is replaced by a fibrous connective tissue that grows from the fibrous ring. The intervertebral disc fuses with the hyaline cartilage covering the surfaces of the vertebral bodies facing each other, and in its shape corresponds to the shape of these surfaces. Between the atlas and the axial vertebra of the intervertebral disc there. The thickness of the discs is not the same and gradually increases toward the lower part of the spinal column, with the disks of the cervical and lumbar spine in the front somewhat thicker than behind. 8 the middle part of the thoracic spine is much thinner than in the higher and lower parts. The cartilaginous part is a quarter of the length of the entire vertebral column.

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