The joints between the vertebrae in the spine are of two main types: zygapophyseal joints (also known as facet joints) and joints involving the intervertebral discs.
Zygapophyseal Joints (Facet Joints)
These are planar synovial joints.
- Location: Connect the articular facets (bony projections) of adjacent vertebrae.
- Type: Synovial joints, meaning they have a joint capsule filled with synovial fluid, allowing for smooth movement.
- Function: Guide and limit the range of motion in the spine, contributing to stability.
Joints Involving Intervertebral Discs
These are cartilaginous joints.
- Location: Between the vertebral bodies (the main, cylindrical part of each vertebra).
- Type: Cartilaginous joints designed for weight-bearing and shock absorption.
- Structure:
- Annulus Fibrosus: A tough, fibrous outer layer that surrounds the nucleus pulposus.
- Nucleus Pulposus: A gel-like inner core that provides cushioning and flexibility.
- Function: Provide cushioning, flexibility, and stability to the spine.
In summary, the spine's intervertebral connections are complex, involving both synovial facet joints for movement and cartilaginous joints via intervertebral discs for shock absorption and weight bearing.
