1. Spinal Vertebra

• There are 24 spinal bones called vertebra – this view shows two vertebra side on. Vertebra are living tissue that will change shape (growing spurs) according to the forces acting on them. The pores on the vertebra are where the blood vessels enter to supply nutrients to the bone.

• The opening formed by the two vertebra is called the intervertebral foramen (IVF). This is where the spinal nerve exits and where nerve irritation often occurs.

• The facet joints are at the rear of the vertebra. These joints are where the vertebrae fixate (lock) and where the pinched nerve sensation begins.

• When the spine is manipulated these facet joints are gapped, (moving less than a millimetre). The decrease in joint pressure causes gas to come out of solution producing the pop sound. The gas dissolves back into the joint fluid within approximately one hour.

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2. Vertebra and Spinal Ligaments

• This view shows the spinal ligaments. The ligaments are similar to stretch canvas. They hold the vertebra together and must be flexible to allow spinal motion.

• Note that the ligaments cross the intervertebral foramen reducing the size of the opening through which the spinal nerve and related vessels can pass.

• Spinal ligaments and the soft tissues surrounding the vertebra are full of nerve endings and become a source of pain when the spine becomes fixated and inflamed.

• With age and lack of stretching these ligaments shorten and harden. This is one cause of repeated spinal fixations and painful injury.

• Chronic inflammation not only causes pain but stimulates ligament calcification, which can contribute to bone spur formation. Keeping the ligaments flexible can minimise the severity of osteoarthritis in the future.

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3. Dissection of Back Muscles

• The spinal nerves exit between the vertebra, passing through the muscles to supply motor function and sensation to the skin, bone and muscles.

• The spinal nerves that originate at one level often travel away from the spine to innervate (supply) different regions of the body. Accordingly, this can mean that where the pain is felt is often not the site of nerve irritation. This is what is meant by “referred pain”.

• Note that there are multiple layers of back muscles. Some short, some longer. The muscle fibres run in a variety of directions to attach to vertebra or ribs or limbs. The muscles should be able to glide easily over each other and the bones. Stretching helps maintain good muscle and spine function.

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4. Inspection of Spinal Cord Laying in Spinal Canal

• The spinal cord is soft and flexible, with a good blood supply. The cord is surrounded by the somewhat tougher dural sac, as well as fat and connective tissue. The dural sac retains the cerebro spinal fluid (CSF) around the cord.

• The departing nerve root is covered by the dural sac only as far as the Dorsal root ganglion (DRG), which is approximately one centimetre from the spinal cord. The spinal nerve and the DRG are vulnerable to irritation as they exit between the vertebra in the IVF.

• Nerve root irritation (compressive or inflammatory) sensitises the nerve, and reduces the movement of fluids (axoplasmic flow) in the nerve fibres. This can cause the sensation of pain (hot or cold), as well as tingling and numbness. Muscular spasm and weakness can also occur.

• The spinal cord and nerve roots need to move freely within the spinal canal for you to remain pain free and healthy. Chiropractic treatment and regular stretching can help you achieve this.

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5. Cross Section of Lumbar Vertebra

• In adults, the disc has minimal blood supply. All nutrition is via diffusion and this is assisted by motion. This is another reason why regular stretching is important to maintain your spinal health.

• When the facet joint becomes fixated (locked), strain occurs and inflammation begins to develop in the bone, ligaments and muscles. This sensitises the nerves in the ligaments and muscles to produce the classic back pain.

• Annular tears (as shown in this cross section of a disc) are quite small and very painful. There is no nerve supply to the inner two thirds of the disc, so you will not feel inner tears until they progress to the outer third of the disc.

• Adult discs are essentially non vascular and therefore even a healthy disc can take 2 to 3 months to completely heal. Bone and periosteal inflammation can take up to 2 months to fully resolve. While ligaments, tendons and muscles are more vascular and can take from a few days up to 2 months to recover.

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