Intervertebral Discs: Overview, Anatomy, and Function
What are Intervertebral Discs?
Intervertebral discs are specialized fibrocartilaginous structures located between the vertebrae in the spine. They act as cushions or shock absorbers, helping to protect the vertebrae during movement such as bending, twisting, and walking. There are 23 discs in the human spine: 6 cervical, 12 thoracic, and 5 lumbar.
Anatomy
Each intervertebral disc is composed of three main parts:
- Annulus Fibrosus: The tough outer ring made of layered fibrocartilage that surrounds the inner core. It provides structural support and resists tensile forces during movement.
- Nucleus Pulposus: The gel-like center rich in water, proteoglycans, and collagen, which distributes hydraulic pressure evenly across the disc when loaded. It acts as the primary shock absorber.
- Vertebral Endplates: Thin layers of hyaline cartilage that separate the disc from the adjacent vertebral bodies and allow nutrient diffusion for disc health.
Intervertebral discs are largely avascular and rely on diffusion through the vertebral endplates for nutrients, making them susceptible to degeneration if nutrient supply is compromised.
Function
The intervertebral discs serve several vital functions:
- Absorbing and distributing mechanical loads placed on the spine.
- Providing flexibility to the spinal column, allowing movement while maintaining stability.
- Maintaining spacing between vertebrae, which is critical for nerve root exit through intervertebral foramina.
- Acting as fibrocartilaginous joints that connect adjacent vertebrae and allow slight motion.
Clinical Considerations
Disc degeneration or injury can lead to conditions such as herniated discs, spinal stenosis, and chronic back pain. The discs’ limited self-healing capacity means damage often persists and requires medical intervention.
Key Points
- Intervertebral discs are fibrocartilaginous cushions between vertebrae composed of annulus fibrosus and nucleus pulposus.
- They provide shock absorption and flexibility to the spine.
- Nutrient diffusion is critical to disc health due to limited blood supply.
- Disc health is essential for spinal stability and nerve root protection.
- Injury or degeneration of discs can cause pain and neurological symptoms.
Consult with Our Team of Experts Now!
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References:
Humzah MD, Soames RW. Human intervertebral disc: structure and function. Anat Rec. 1988 Apr;220(4):337-56. doi:10.1002/ar.1092200402. Available at: https://pubmed.ncbi.nlm.nih.gov/3289416/
