Spinal Column (Vertebral Column)

The primary functions of the spine are to maintain the structure of the trunk and allow for body mobility, to protect the spinal cord (nervous system), and to act as a shock absorber. The column is composed of 33 short bones called vertebrae and 23 intervertebral discs, and has 4 distinct anterior-posterior curves. Vertebral bodies in the lumbar region are thicker and wider to sustain larger loads. The intervertebral disc bears and distributes loads and restrains excessive motion.

Movements of the spinal column include flexion, extension, lateral flexion, and rotation. From the vertebral-column diagram (Harter, 1991), the regions and curves are: cervical curve (7 vertebrae), thoracic curve (12 vertebrae), lumbar curve (5 vertebrae), sacrum (5 fused vertebrae), and coccyx (4 fused vertebrae). When positioning and stabilizing the spine, hold it in a semi-isometric contraction to keep it in an "S" shape; never allow a "C" shape spine during exercise.

Back (erector spinae) disorders are usually the result of poor posture, faulty body mechanics, loss of flexibility, decline of physical fitness, and stressful living/working conditions. Tight hamstrings is also a cause of back problems. 80 to 90 percent of the general population will experience back pain sometime in their lifetime.

• 33 vertebrae; 23 intervertebral discs; 4 anterior-posterior curves.
• Regions: cervical (7), thoracic (12), lumbar (5), sacrum (5 fused), coccyx (4 fused).
• Functions: support trunk/allow mobility, protect spinal cord, absorb shock.
• Lumbar vertebral bodies are thicker/wider for larger loads.
• Movements: flexion, extension, lateral flexion, rotation.
• Hold the spine in an "S" shape (never "C") during exercise.
• 80–90% of the general population will experience back pain in their lifetime.