They key components of the human spine are grouped into three regions: the cervical spine, thoracic spine and lumbar spine. The cervical spine is the spine's uppermost region, the thoracic spine is the midsection and the lumbar spine is the lower region.
The cervical spine is comprised of seven vertebrae. The vertebrae are numbered from top to bottom, ranging from C1 to C7. The top two vertebrae, C1 and C2, are called the atlas and the axis, respectively. They allow for neck movement and are positioned between the rest of the spine and the skull. The cervical spine is also the location of the first spinal curve, called a lordotic curve.
The thoracic spine has 12 vertebrae, numbered T1 to T12. The thoracic vertebrae are where the ribs attach to the spine. The thoracic spine curve is called a kyphotic curve, and it bends outward like a backward letter C.
The lumbar spine typically has five vertebrae, numbered L1 to L5. Some individuals have six vertebrae in the lumbar spine region. The lumbar spine vertebrae are the largest vertebrae, and they bear the bulk of the body's weight. The lumbar spine curve, like the cervical spine curve, bends inward and is also called a lordotic curve.
The round, flat pads that cushion the space between the vertebrae are called intervertebral discs. The discs are composed of a soft gel-like center called the nucleus pulposus and a strong outer layer called the annulus. Soft tissue and nerves are also part of the human spine.