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Spine Anatomy
The spine is a complex mechanical structure that functions to:
- protect the spinal cord and nerve roots
- provide the flexibility necessary for bending and twisting motion
- provide structural support and bear the weight of the upper body
The building blocks of the spinal column are individual bones called vertebrae. Ligaments and muscles attach to the back of the spine and provide further support and power for movement.
Vertebrae
Each vertebra is numbered from the top of the spine to the bottom, so the top vertebra in the lumbar spine is called L1, while the bottom vertebra in the lumbar spine is called L5.
These vertebrae are divided into regions, as follows:
- C1–C7: cervical vertebrae (neck)
- T1–T12: thoracic vertebrae (upper back)
- L1–L5: lumbar vertebrae (lower back)
- sacrum
- coccyx (or tailbone)
Intervertebral Discs
Intervertebral discs are located between each vertebra from C2-C3 to L5-S1. They are made of strong, fibrous tissue filled with a cushioning gel. Together, the discs make up about one-fourth of the total height of the spinal column. They act as the spine’s shock absorbers and allow smooth movement of the spine. Together, two adjacent vertebrae and the disc in between make up a motion segment of the spine.
