The back is the large posterior area of the torso extending from the neck to the pelvis that is comprised of connected nerves, bones, muscles, ligaments and tendons. The vertebral column, or spine as it is more commonly known, supports the height of the back and has three major regions – cervical, thoracic, and lumbar.
Upper back pain may have numerous sources but is typically associated with the thoracic region of the spine. The thoracic spine has 12 vertebrae, T1-T12, which join the cervical spine at the bottom of the neck and extend to the lumbar spine in the lower back. Each vertebra of the thoracic spine attaches to a rib on either side, providing stability for the entire body. As a result of its stabilizing function, the thoracic spine has limited flexibility. While the cervical and lumbar regions of the spinal column have lordotic curves, meaning they curve outward, the thoracic spine has a kyphotic curve, as it curves inward.
Lower back pain often occurs as a result of injury to the lumbar spine, which usually has five vertebrae, but can have six. The lumbar spine attaches to the sacrum, which connects the lumbar spine to the coccyx, or tailbone. All of these regions may be the source of lower back pain. The lumbar spine is distinguished from the thoracic spine by its flexibility, connecting to the sacrum at the lumbosacral joint, which permits significant rotation of the pelvis. Additionally, the lumbar spine is composed of the largest and strongest bones in the spine as it supports the majority of the body’s weight. Injuries and degradation of the lumbar spine often occur at the bottom two vertebrae, which bear the most weight mindmedical.com.