THE ANATOMY OF THE LOWER BACK

When it comes to understanding the cause of low back pain it is important to have a
clear concept of the major anatomical components. The most important structures of
the lower back include: the vertebrae (lumbar spine), discs between the vertebrae,
ligaments around the spine, spinal cord as well as the nerves exiting that region and the
muscles of the lower back.

The bones of the lower back are stacked one on top of the other with a natural curve
forward called a lordosis. This natural curve gives the low back its strength. The spinal
cord is housed in these bones and branches off to exit via the nerve roots.

There are five lumbar vertebrae that sit immediately atop the sacrum bone situated
between the buttocks. The sacrum joins the major bones of the hips (illium) on both
sides. These joints are called the sacro illiac joints.

                                 
                                                                  (Source: Texas Spine and Joint Hospital)

Between each vertebrae of the lower back is a lumbar disc which serves as a shock
absorber or a cushion between the joints. Each disc has a strong fibrous outer layer
surrounding a soft central component, a bit like a jelly donut. If this disc bulges or even
ruptures (herniated disc) it can cause irritation or pressure on the nerve root exiting the
lumbar bones.

Ligaments are the strong fibrous tissues that firmly attach bones to bones in the low back,
as well as surrounding each disc. There are also a number of quite large muscles that
support and move the lower back including gluteals on the buttock, multifidus through
the middle, quadratus lumborum a large flat muscle above the hips as well as hip flexors
and your core muscle TA (transversus abdominus) through the front.

If you would like to know more about the anatomy of your lower back, please don't hesitiate
to give our friendly physiotherapists a call on 07 3847 8040. You can also check out our 
8 Most Common Causes of Lower Back Pain resource for more information on what may be
causing your pain and our How to Address Your Lower Back Pain resource to learn how you
can begin to help ease your pain.