Back Muscles, Abdominal Muscles and Ligaments

What are the key back muscles

Back muscles play an important role in allowing your spine to do its job properly. They give the spine extra support and allow movement to take place.

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Many people don't realise that the muscles in your abdomen and pelvic floor also play an important role in giving the spine support.

There are many different back muscles associated with the human spine. Some are designed to add support and stability; others are designed to move the spine. There is a close relationship between these different types of muscles.

These muscles that add support are also often referred to as the core muscles or core stabilisers.

The following diagrams show the main abdominal muscles:

You can't see all these muscles from the surface. The transversus abdominus is the deepest of all the muscles.

There is a lot of research currently underway looking at the relationship between this muscle and back pain. You may hear transversus abdominus talked about a lot as one of the key 'core stabilising' muscles.

The next layer up is the internal oblique and the external oblique sits above that. The rectus abdominus sits in the centre and makes up the 'six pack'.

When most people think of abdominal strength exercises they tend to think of exercises that strengthen this muscle. In fact much of the abdominal muscle work we do in physiotherapy concentrates on the other muscles - the core stabilisers. See some core stability exercises here

If you imagine for a moment that your trunk is a cylinder.

• the roof of this cylinder is made up of the diaphragm, or breathing muscle
  
  
• the floor is made up of the pelvic floor, (the muscle that stops you going to the toilet when you tighten it)
  
  
• the walls of the cylinder are made up of the abdominal muscles.

If the abdominal muscles and pelvic floor are strong and supportive they stiffen the cylinder and give the spine good support. The image below shows the layers in the walls of the cylinder, as if you are looking at a slice from the head down (just one side is shown here).

Spinal Ligaments

The bones, discs and joints are connected together and given excellent flexibility by tough bands of cartilage called ligaments.

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There are many ligaments in the spine. The diagram below shows some of them.

I won't name them all but you can see that they pass between all the different parts of the vertebrae including the parts that stick out at the back and sides (the spinous and the transverse processes).

A sleeve of ligamentous tissue, called the capsule, also surrounds each facet joint. This keeps each joint fully enclosed, adding extra support and protection.

Diagram of the spinal ligaments

The Human Spine - Overview

Overview of the spine

More detail about vertebrae

All about Spinal Discs

Spinal Cord Anatomy

Lower Back Pain Toolkit Home Page

Weak back muscles may contribute to simple low back pain - read an overview of causes of back pain.

21-Jan-2011