Intervertebral Discs

In order for the bony spine to achieve its mobility, flexible connections between the vertebral bodies are required, which on the one hand allow the vertebral bodies to tilt or rotate and on the other hand provide a firm hold of the vertebral bodies on each other. The Disci fulfil both functions and also serve as a buffer against short hard impacts. Each disc resembles a sandwich with two solid plates of hyaline cartilage, between which a coarse onion-shell-like fibrous ring (Anulus fibrosus) spreads around a central nucleus (Nucleus pulposus). Due to its high osmotic concentration, the gelatinous core attracts water from the environment and swells in an unpolluted state. This lengthens the spine by up to 2 cm and the fibrous ring gets under tension. If you squeeze only the "sandwich" together (pressure load), the gelatin core will try to avoid it laterally. The cross-linked collagen fibres of the fibre ring are stretched and the fibre ring bucks beyond the edge of the vertebral body (tensile load). The result is a compression of the nerve cords in the spinal cord with the corresponding pain and loss of function of the muscles supplied.