The vertebral column is a series of vertebrae, or spinal bones, joined by discs, joints and ligaments. It lies along the back of the neck and trunk, extending from the skull to the pelvis, and supports the body while enclosing a protective canal for the spinal cord.
Where is the vertebral column located?
The vertebral column forms part of the axial skeleton, the bones of the head and central trunk. Its upper end meets the skull, while its lower portion includes the sacrum, a fused bone that joins the hip bones. Together, the sacrum, coccyx and hip bones form the bony pelvis. The sacrum and hip bones form the pelvic ring connecting the trunk to the lower limbs.
In the neck, the column lies behind the pharynx, the passage behind the nose and mouth, and the oesophagus, the muscular tube carrying food towards the stomach. In the chest, it lies behind the oesophagus and between the posterior attachments of the ribs. In the abdomen, it lies behind major organs and blood vessels, including the aorta, the main artery leaving the heart.
The vertebral canal is the continuous passage within the column. It contains the spinal cord, the part of the central nervous system connecting the brain with spinal nerves, and the coverings and nerve roots associated with it. In adults, the cord usually ends in the upper lumbar region; lower nerve roots continue down the canal.
What are the regions of the vertebral column?
The regions differ in their vertebral shape and attachments. The neck and lower back are relatively mobile, whereas the rib attachments limit movement in the chest.
| Region | Main components | Distinguishing anatomy |
|---|---|---|
| Cervical vertebral column | Seven neck vertebrae | Supports the head; transverse processes contain openings |
| Thoracic vertebral column | Twelve chest vertebrae | Bears joint surfaces for the ribs |
| Lumbar vertebral column | Five lumbar vertebrae | Has large vertebral bodies suited to weight-bearing |
| Sacral region | Sacrum | Fused vertebrae connect the column to the hip bones |
| Coccygeal region | Coccyx, or tailbone | Small terminal vertebrae provide attachment for pelvic muscles and ligaments |
The atlas is the first cervical vertebra. It supports the skull and lacks a typical vertebral body. The axis, the second cervical vertebra, has a dens: an upward bony projection around which the atlas and head rotate.
What are the landmarks of a typical vertebra?
A typical vertebra has an anterior body and a posterior arch. Anterior means towards the front of the body; posterior means towards the back. The body carries much of the compressive load, while the body and arch together bound the vertebral foramen, the opening contributing to the vertebral canal.
The main landmarks are:
- Pedicles: short bony bridges forming the anterior parts of the arch and connecting the body to its posterior elements.
- Laminae: plates of bone forming the posterior part of the arch.
- Spinous process: a backward projection providing attachment for muscles and ligaments.
- Transverse processes: sideways projections providing attachment; in the thoracic region, most also articulate with ribs.
- Articular processes: upward and downward projections bearing facets, the smooth surfaces that form joints with neighbouring vertebrae.
Notches above and below each pedicle help form an intervertebral foramen between adjacent vertebrae. This is a side opening through which a spinal nerve passes. A spinal nerve carries signals between the spinal cord and structures elsewhere in the body.
How are vertebrae joined together?
An intervertebral symphysis is a joint between neighbouring vertebral bodies connected by an intervertebral disc. A symphysis is a joint in which fibrocartilage, a tough cartilage containing collagen fibres, connects the bones. These joints occur from the axis down to the sacrum; there is no disc between the atlas and axis.
Each disc has an outer annulus fibrosus, a ring of fibrous tissue, and an inner nucleus pulposus, a softer central core. Discs distribute pressure between vertebral bodies and deform slightly during movement.
Facet joints connect the articular processes of adjacent vertebrae. They are synovial joints, meaning their opposing surfaces lie within a capsule enclosing a fluid-containing joint cavity. Their orientation helps determine which movements are available in each region.
Ligaments are strong bands of connective tissue joining bones. The anterior and posterior longitudinal ligaments run along the front and back of the vertebral bodies respectively. Other ligaments connect the laminae, spinous processes and transverse processes, helping limit excessive movement.
What are the normal curves of the vertebral column?
Viewed from the side, the cervical and lumbar curves are convex forwards, while the thoracic and sacral curves are convex backwards. These normal curves help balance the head and trunk over the pelvis and contribute to the column’s resilience under load.
The thoracic and sacral curves are called primary curves because they are present during fetal development. The cervical and lumbar curves are secondary curves that develop as head control and upright posture emerge.
What does the vertebral column do?
The vertebral column supports the head and trunk and transfers their weight towards the pelvis. It protects the spinal cord and provides attachment for ribs, muscles and ligaments.
Movement includes flexion, or forward bending; extension, or backward bending; lateral flexion, or side bending; and rotation, or turning. Small movements between successive vertebrae combine into larger movements of the neck and trunk. The fused sacrum provides a stable connection rather than the mobility found between separate vertebrae.
How can you explore the vertebral column in the 3D model?
In the 3D model next to this article, rotate to a side view, then zoom towards a region. Select, hide or isolate parts, fade selected parts, or pull parts apart. Switch layers on and off as you navigate, or cut a section along the sagittal plane, which divides left from right. You can also cut a section along the coronal plane, which divides front from back, or the transverse plane, which divides upper from lower.