What is the spine?

Author: SCIRE Community Team | Reviewer: Riley Louie | Published: 21 September 2017 | Updated: ~

The spine is a long column of 33 small back bones called vertebrae that are connected together by strong fibrous ligaments and shock-absorbing fibrous discs. The spine is part of the skeleton.

The spine supports the weight of the body, allows the torso to move, anchors many of the muscles, and protects the spinal cord from damage. The spine is also called the vertebral column, spinal column, or backbone.

The five major areas of the spine.¹

• The cervical spine has 7 cervical vertebrae and forms the neck.
• The thoracic spine has 12 thoracic vertebrae and forms the upper and mid back.
• The lumbar spine has 5 lumbar vertebrae and forms the low back.
• The sacrum is made up of 5 sacral vertebrae that are fused together to form a wedge-shaped bone that is part of the pelvis.
• The coccyx is made up of 3 to 5 coccygeal vertebrae that are fused together to form the tailbone.

The spine has a hollow canal in its centre that runs the length of the spine from the base of the skull down to the sacrum called the spinal canal. The spinal canal contains the spinal cord.

The bones of the spine are named and numbered according to:

• The area of the spine that the bone is located in (cervical, thoracic, lumbar, or sacral), which is often abbreviated simply as a letter (i.e. ‘C’ for ‘cervical spine’ or ‘C-spine’, ‘T’ for ‘thoracic spine’ or ‘T-spine’); and
• The number of the bone within that area. The numbering begins at ‘1’ for the vertebra closest to the head and increases with each vertebra down to the tailbone (counting up as you move down the spine). The numbering then begins again at ‘1’ in the next area of the spine.

For example, the bone at the top of the lumbar area of the spine (the low back) is called the ‘first lumbar vertebra’ or ‘L1’.