Intervertebral Joints

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Chapter: Anatomy and Physiology for Health Professionals: Support and Movement: Articulations

Between superior and inferior articular processes of adjacent vertebrae in the spine are found intervertebral joints (articulations).

Intervertebral Joints

Intervertebral Joints

Between superior and inferior articular processes of adjacent vertebrae in the spine are found intervertebral joints (articulations). These are glid-ing joints, allowing small movements such as flexion and rotation of the spinal column. However, only slight gliding occurs between adjacent vertebrae. Therefore, the vertebrae are separated and cushioned by intervertebral discs, which are pads of fibrocartilage (FIGURE 8-9). The bodies of the vertebrae form sym-physeal joints. These joints are present between the axis and sacrum of the spine, but are not present in the sacrum or coccyx. In these locations, the vertebrae are fused. Also, the joints between the first and second cervical vertebrae are fused. Actually, the first cervical vertebra does not have a vertebral body or an inter-vertebral disc. Therefore, between the first two cer-vical vertebrae, there is a pivot joint that allows for a greater amount of rotation than the symphyseal joints between other vertebrae.

Throughout most of the spine, each intervertebral disc has a tough outer layer of fibrocartilage known as the annulus fibrosus. Collagen fibers attach this fibro-cartilage to the bodies of adjacent vertebrae. Inside the annulus fibrosis is the nucleus pulposus, a core that is softer, gelatinous, and more elastic. Intervertebral discs absorb shocks and have resiliency because of each nucleus pulposus. Thin vertebral end plates nearly cover the superior and inferior surfaces of each disc. The plates are made up of fibrocartilage and hya-line cartilage. When movement occurs, the vertebral column compresses the nucleus pulposus, displacing it in opposing directions. Gliding movements can occur while vertebral alignment remains constant.

Intervertebral discs make up nearly one-fourth of the length of the vertebral column superior to the sacrum, greatly contributing to an individual’s height. However, aging causes water content of each nucleus pulposus to decrease, reducing their cushioning actions. This raises the chance of vertebral injury. The water loss results in vertebral column shortening, and the older individual actually becomes shorter over time.

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