The adult spine contains 24 vertebrae, not including nine bone segments in the pelvic region that begin as separate vertebrae at birth but fuse during childhood and adolescence to form the sacrum and the coccyx. The 24 non-fused vertebrae are grouped into three regions – cervical (neck), thoracic (middle back) and lumbar (lower back). There are seven cervical vertebrae, 12 thoracic vertebrae and five lumbar vertebrae, all of which possess unique characteristics that differentiate them from the other regions.
Before exploring the differences among the vertebral regions, it’s important to understand that from the top of the spine to the bottom, vertebrae do, in fact, share some consistent characteristics. The most obvious is the fact that all are composed of bone. Another common characteristic is general function – the vertebrae are there, primarily, to support the body and protect the spinal cord. In addition, the vertebrae are separated by cartilaginous cushions called intervertebral discs. The one exception is at the very top of the spine, where the first cervical vertebra (the atlas) pivots on a flange that sticks up from the second cervical vertebra (the axis).
Differences Among Vertical Regions
The major differences among the three spinal regions lies in shape and secondary function. Here is a brief description of the characteristics unique to each region:
- Cervical – smaller bones support the weight of the head and are flexible to allow a wide range of head movement; also, the axis is the only vertebra with no vertebral body
- Thoracic – larger bones than in the cervical region; more rigid to provide a framework for the ribcage and the torso in order to protect the inner organs
- Lumbar – largest bones in the spine; support most of the weight of the upper body and allow for bending, twisting and hip flexion
Because of their weight-bearing function and relative flexibility, the cervical spine and lumbar spine are more vulnerable than the thoracic spine to degenerative conditions within the vertebrae. Chronic back or neck pain can result from spinal conditions such as herniated disc, bulging disc, degenerative disc disease and osteoarthritis. If this happens to you, contact Laser Spine Institute to learn what thousands of patients already know – our minimally invasive, outpatient procedures can help you rediscover a life without pain.