Understanding your spine and lower back.

Ankylosing spondylitis (AS), the whole spine is affected.The symptoms usually begin in the low back. To understand how ankylosing spondylitis can cause your spinal bones to fuse, you must have a basic knowledge of how your spine works.

 Your backbone, also called your vertebral column, support a lot of your body weight, and protects your spinal cord. As you can see from the image below spine, is made up of many parts. First, we're going to look at the spine structure.You have 33 vertebrae (bones) that constitutes the vertebral column.

                              

Your spine is divided into regions:
There's your neck (cervical spine), mid-back (thoracic), and low back (lumbar spine). At the bottom of your spine you have your tailbone. Again, AS generally starts in the lumbar spine and spreads way up to the cervical spine.

The vertebrae in your neck are labeled C1-C7, meaning that you have 7 vertebrae in that region.

Most adults have 12 vertebrae in the thoracic spine (T1-T12), which goes from your shoulders to your waist.Then there are 5 vertebrae in your low back (L1-L5).

In between your vertebrae, you have intervertebral discs (also labeled on the image). These act as pads or shock absorbers for your spine as it moves.

Together, the vertebrae and the discs provide a protective tunnel (the spinal canal) to house the spinal cord and spinal nerves. These nerves run down the center of the vertebrae and exit to various parts of the body, where they help you feel and move. With ankylosing spondylitis, your spinal nerves can be pinched (also known as impinged or compressed) by the extra bone that develops as a result of AS.

The joints are covered by cartilage that protects your bones as you move. In ankylosing spondylitis, the cartilage can be destroyed—inflammation and chemicals released by the inflammation can destroy it.

UNDERSTANDING LOWER BACK. 

The vertebrae are circular and between each vertebra is a disc. The discs are made of strong rubber-like tissue which allows the spine to be flexible.  There are also various muscles that are attached to the spine which enable the spine to bend and move in various ways. There are also small facet joints that help to attach vertebrae to each other. The sacrum is formed from five fused vertebrae that are joined together.Strong ligaments also attach between adjacent vertebrae to give extra support and strength to the spine. They form a triangular shaped structure. The two sacroiliac joints are the large long joints that join the sacrum to the ilium (the main bone of the pelvis).