The Anatomy of the spine

The spinal column (spine) is the body’s main support structure.  It is made up of 33 bones, called vertebrae, stacked one upon another.  

The spine is divided into five regions:


The Regions of the Spine


Cervical Region
The cervical region of the spine is made up of seven vertebrae labeled C1 to C7. The main function of the cervical spine is to support the weight of the head.

The cervical spine has the greatest range of movement of any part of the spinal column. This is partly because of two specialized vertebra, the atlas and the axis, that connect the spine to the skull and enable the head to turn left and right and nod up and down.

Thoracic Region
The thoracic region is located in the mid-back.  Its main function is to protect the organs of the chest, particularly the heart and the lungs.  There are 12 thoracic vertebrae, labelled T1 to T12, with one rib attached to each side.  These create a thoracic cage around the internal organs of the chest.

Lumbar Region
The lumbar region, commonly known as the lower back, is made up of five vertebrae labeled L1 to L5. These lumbar vertebrae are the largest of all the vertebrae and form the main weight-bearing section of the spinal column.

Sacral region
The sacral region consists of five vertebrae, labeled S1 to S5, which are fused together in a solid unit, known as the sacrum. This is the point at which the spinal column attaches to the pelvis.

Coccygeal Region
At the end of the spinal column is the coccygeal region, more commonly called the coccyx or tailbone.  This consists of four small vertebrae, to which various muscles, tendons and ligaments are attached. The coccyx also helps to support a person’s body in the sitting position.


The Components of the Spine


Together, the vertebrae of each of the spine’s five regions support the weight of the body and protect the spinal cord and its nerve roots.  Each individual vertebra has a complex set of unique features that are vital to the overall function of the spine.

Every vertebra has three basic functional parts: 

Vertebral Canal
When the vertebral bodies are stacked one on top of another in the back, they create a vertical tunnel (behind the vertebral bodies) called the spinal canal or neural canal, through which the spinal cord runs.  The spinal canal runs from the cervical region to the sacrum.

Spinal Cord
The spinal cord is a long, thin tubular bundle of nerve fibers connecting the brain to the rest of the body.   Together, the brain and the spinal cord make up a person’s central nervous system.  The spinal cord ends near the L1 and L2 vertebrae, where it divides into bundles of nerve roots called the cauda equina.

Nerve Roots
Exiting the sides of the spine, all the way down, are nerve roots:  32 pairs of thick nerve branches that transmit signals between the spinal cord and all other parts of the body.

Pedicles & Lamina
On either side of the vertebral canal are the pedicles or pedicle bones (hard, tubular structures) which connect the vertebral body to the lamina: the outer wall of the vertebral canal, which covers and protects the spinal cord.

Spinous Process
As the lamina come together at the back of the spinal column, they join to form the spinous process.  This is the bony part of the spine that you can feel protruding from your back.

Transverse Processes
Protruding from the sides of each vertebra are two transverse processes, or lateral projections, one on each side.  These serve as points of attachment for muscles and ligaments in the spine, which move and stabilize the vertebrae.

Articular Facet
The articular facets are the joints where each vertebra connects with the one above and below it.  Each vertebra has four facets (two superior facets and two inferior facets), all covered with cartilage, to facilitate movement.

Intervertebral Discs
Sandwiched between each of the vertebral bodies are tough, elastic spinal discs. These provide a flexible cushion and allow the vertebrae to bend and twist.


Conditions affecting
the spine