The musculoskeletal system is comprised of bones, joints, muscles, tendons, cartilage, and ligaments; they function together to support the body and allow movement. The spine is called the vertebral column and is the main central support of the body. It is made up of approximately 33 bones, called vertebrae, and is divided into 5 regions: cervical (7 bones), thoracic (12 bones), lumbar (5 bones), sacrum (3-5 fused bones) and coccyx (4 fused bones). When viewed from the front or back, the spine is straight. When viewed from the side, each region has its own natural curve. [View Image] The thoracic spine and sacrum form a C-shaped curve when viewed from the side with the midpoint of the curve pointing back. This is called kyphosis. The cervical and lumbar regions curve in the opposite direction, putting sway into the neck and back, called lordosis.

The basic movements of the back are extension (straightening the spine, bending backward), flexion (bending the spine or torso forward), lateral bending (bending the spine to the side), and rotation (twisting the spine). It is the muscles and ligaments of the vertebral column that allow control and coordination of these movements.

The joints of the vertebral column include the intervertebral discs and facet joints, both of which contribute to the spine moving and bending freely. [View image]. The spinal cord is made up of nerves and nerve cells and travels inside the vertebral column. The vertebral column protects the spinal cord and the spinal nerves as they exit the spinal cord and proceed to the body's muscles, joints, skin, organs, and other vital tissues. [View Image]