Advanced Search

Orthopedic Coding Alert

The Anatomy of the Spine

Published on Sat Jun 01, 2002

The human spine is divided into three major sections: cervical, thoracic and lumbar. The cervical spine begins at the base of the skull (occiput) and contains seven vertebrae and eight pairs of cervical nerves that control the neck, arms and upper body. The seven cervical vertebrae are referred to as C1-C7. Injuries to this portion of the spine can result in radiating pain in the neck, shoulder and upper extremities. The thoracic spine is the midsection of the spine, and contains 12 vertebrae (T1-T12) and 12 pairs of ribs and nerves that control the body's midsection. Because this portion of the spine is stabilized by the rib cage, injuries are less common than at the cervical or lumbar spine.

The bottom of the spine its strongest region is the lumbar spine. There are five lumbar vertebrae designated L1-L5 and five pairs of lumbar nerves that control movement and sensory function in the lower extremities. The lumbar region carries the bulk of the body's weight and is a common injury site. Injuries to this area can cause radiating pain or sciatica in the legs, as well as pain in the distant lower extremities.

The nonbony area between vertebrae is called a vertebral interspace. In surgical terms, aspects of the back are operated on and so designated based on the numerical system (C2, L5, etc.). Consequently, when an operative report indicates that a surgery took place at L5-S1, the region is the fifth lumbar vertebra, including the interspace between L5 and S1 (or sacrum) and the disc and facet joints. A surgery at C7-T2 includes three vertebrae and segments, from the seventh cervical to the second thoracic, including the first thoracic.

Each vertebra is made up of several parts, any or all of which may come into play during a spinal procedure:

  • Vertebral body The largest part of the vertebra, the vertebral body is a thick block of bone on the front, or anterior side, of the spine and is the primary weight-bearing area of the spinal column.
  • Spinous process The large bony protrusion you feel when running your hand down your back, the spinous process forms the back of the vertebra.
  • Transverse process On either side of the spinous process at 90-degree angles, the transverse process is two bony protrusions to which back muscles attach.
  • Foramina Also called the spinal canal, this is the hole in the center of the vertebra through which the spinal cord and nerves pass.
  • Lamina The lamina is the protective covering of the spinal cord and nerves posteriorly.
  • Facet joints Four facet joints, two on the top and two on the bottom of each vertebra, interlock to connect the vertebrae to one another.
  • Intervertebral disc The space between each vertebra is separated by intervertebral discs that cushion the bones.

    • Other Articles in this issue of

    Orthopedic Coding Alert

    View All