It’s behind you

    21 February 2015

    Call it what you want — spine, vertebral column, backbone or back — it’s there to support us throughout out life. Without it we’d be a lump on the floor, of little use to anyone.

    The back extends from the neck and shoulders to the top of the buttocks. It consists of the spine and a range of muscles that enable us to bend forwards and backwards and from side to side, and to move our neck and shoulders. It is covered by a layer of tough skin that as well as being thicker than elsewhere on the body also has fewer nerve endings.

    The spine extends from the skull to the pelvis and is made up of 26 bones. That’s 24 separate vertebrae — grouped into seven cervical, 12 thoracic and five lumbar — plus the sacrum and the coccyx, or tailbone. In front of the upper part of the spine is the ribcage that protects the lungs.

    A vertebra is a ringlike bone. Granted, it’s an odd-shaped ring with bits sticking out from it like a starfish. Each vertebra has a hole in the middle and when stacked on top of each other a tunnel, called the spinal canal, is created. Imagine having a stack of Polo mints, or ring doughnuts, then you’ll get the picture. In fact, if you wanted to build your own model spine, this would be one way of doing it.

    The spinal canal enables a bundle of nerve fibres — the spinal cord — to pass safely through from the brain. Small openings formed between adjacent vertebrae allow nerves to branch off the spinal cord and travel to various parts of the body through which nerve messages can be transmitted to and from the brain, and to and from the rest of the body.


    Each vertebra sitting on top of the other forms the spinal column. It’s not a perfectly upright column, though, but one that creates the appearance of the letter ‘S’ when viewed from the side of the body. The S-shaped spine helps avoid a shock to the head when running or walking. In addition, in between each vertebra is a vertebral disc whose function is to act as a shock absorber between two vertebrae.

    Discs are made up of an outer fibrous shell within which is a gel-like filling — I see we’re back to doughnuts again! More accurately called intervertebral discs because of their location in the body, these important structures don’t only act as shock absorbers but also behave like a flexible glue since while holding adjacent vertebrae together — and preventing them from grinding against each other — they also allow some movement of the vertebrae.

    Of course, the spine would be a bit wobbly if it were just a tower — you’ve seen young children building towers with bricks haven’t you? So to stabilise it muscles and ligaments provide the support it needs. It’s actually injury to these, rather than to the vertebra or discs themselves, that’s responsible for the most common back problem — low-back pain.

    The coccyx, or tailbone, is often thought of as having no real purpose other than to cause pain when landed on heavily. It does, however, serve as an effective anchoring point for some muscles, ligaments and tendons. It’s also weight-bearing when we’re sitting down.

    So what does the spine actually do? Essentially it helps us hold our head up high, keeps our body upright and protects the delicate nerves that make up the spinal cord as these traverse the spine from the brain to the rest of the body. It also enables us to bend and twist in various directions, for the most part without problem.

    Top views of vertebrae
    Top views of vertebrae

    Back pain is one of the commonest health complaints. It most often occurs in the lower back as a consequence of minor injury, sprains and strains involving muscles, tendons and ligaments. Poor posture, twisting or bending awkwardly and lifting objects incorrectly are often responsible. It may also occur due to irritation of a nerve from pressure of a herniated, or ‘slipped’, disc. When the sciatic nerve, the largest single nerve in the body, is irritated in this way it’s called sciatica.

    The spine can become inflamed in a condition called ankylosing spondylitis. Although it’s not clear why this occurs it results in back pain, back stiffness and a reduction in spinal movement.

    To remain strong our bones need an adequate supply of calcium, found in good amounts in dairy products, sardines and some vegetables and beans. To be efficiently absorbed into the body calcium requires the assistance of vitamin D, known as the sunshine vitamin since most of the vitamin D in our body is manufactured in the skin in response to sunlight. Bone is continually being broken down and rebuilt — in fact, it’s estimated that we get a completely new skeleton every ten years. During the early years of life more bone cells are laid down in bone than are lost. However, from our mid-thirties onwards the reverse is true. It is for this reason that the bone disease osteoporosis, or brittle bone disease, develops as the bones become less dense. In turn, this reduction in bone strength makes fractures more likely. Although bone fractures due to osteoporosis can occur anywhere in the body the spine is one of the areas most frequently affected.

    Despite being such a key component of the human body the back is usually ignored — until something goes wrong. So it’s our duty to look after our backs, particularly in this day and age when everyday modern lifestyles make back problems more likely to occur. Spending increasing amounts of time sat at and hunched over a desk means poor posture — a major contributor to back problems — is more likely to be present. Being overweight puts an enormous strain on the back muscles, making low-back pain more likely to come a person’s way. And the need to get everything done as quickly as possible means that we often forget that awkward twisting and bending — for example, to pick up the pen that’s dropped off our desk — can so easily leave us in great discomfort.

    So what can we all do to support our back and lessen the chance of it telling us it’s not happy? Well, maintaining a good posture is an essential first step. Since much of our life is now spent sitting in front of a computer it’s vital to ensure that the workstation is appropriately set up. This includes making sure objects to be used are easily accessible, that the screen is at eye level, and the chair supports the lower back.

    Exercise and keeping active helps the back by strengthening the supporting back muscles and by helping to keep a healthy body weight that in turn means the back is subjected to less pressure. When lifting, bending at the knees and keeping the back straight is the way to do it, while remembering not to bend and twist at the same time. A healthy balanced diet should deliver plenty of calcium, and vitamin D from a little sun exposure during the summer months will help keep the bones of the spine strong. Smoking can reduce blood supply to the discs meaning they may be likely to degenerate over time — another good reason to give up.

    Your back is there for you throughout your life. Support it, so it can support you.