The spine is literally the backbone of the body, starting at the neck and ending at the tailbone. Every day our spines withstand a lot of stress, making it a common site of overuse pain and injury. The spine is composed of 33 vertebrae that are grouped into regions defined by their location and function.
The spine is composed of the following vertebrae, from top to bottom:
- 7 cervical vertebrae (C1-C7)
- 12 thoracic vertebrae
- 5 lumbar vertebrae (L1-L5)
- 5 fused sacral vertebrae (S1-S5)
- 4 fused coccyx (tailbone) vertebrae
The cervical vertebrae in the neck are responsible for neck flexion/extension, rotation and bending. The thoracic spine is connected to the rib cage and primarily functions to give the body support with very little motion. The lumbar spine (the lower back) allows the spine to flex (bend forward) and extend (bend backwards). The sacrum and coccyx are fused and function to connect the spine to the pelvis.
The spinal cord runs from the brainstem down to the lumbar spine in a canal and is surrounded and protected by vertebrae bones. Nerves that control muscle function begin in the brain, travel to the brainstem, move the spinal cord and exit the spinal cord toward to the muscle they control. Similarly, sensory nerves originate in the skin or muscle of the body, and then travel to the spinal cord up to the brainstem and end in the brain for processing.
Muscles and very strong ligaments support the spine and maintain stability, while also allowing movement (flexion/extension, rotation and bending). The intervertebral discs sit between each of the stacked vertebrae in the spine and cushion the vertebrae during movement.