THE SCOOP

ON YOUR BACK

During my years in medical school and as a neurosurgeon, I have read many books on the anatomy of the back. Invariably, the authors of each book attempt to use some kind of analogy to try to describe what the back looks like and how it operates. I have seen the back compared to many different structures and contraptionsfrom the Eiffel Tower to an articulating crane. But, as far as I can see, none of these metaphors adequately describe your back.

It's obvious why doctors and other writers attempt to make these comparisons. Few peopledoctors includedwant to wade through long, drawn-out anatomical descriptions that either lull the reader into a stupor or leave them more confused than when they started. Unfortunately, there is no way to write a book about taking care of the back without providing at least a few basics on anatomy. It has been my experience that this can't be done without a full complement of illustrations.

So, instead of trying to make another ineffectual comparison of the back to some obscure object, I am going to try to give youas briefly and as painlessly as possiblethe scoop on

Four Weeks To A Better Back

Basic structure of the human vertebrae,
complete with nerves, discs and spinal cord.

your back. Included also in this chapter are several graphics that probably will do much more than my words in giving you a more clear understanding of both the anatomy of your back and how it works.

After the brief anatomy lesson, I will then tell you, again as painlessly as possible, how your back works. If you are thinking about skipping this chapter, give yourself a break and don't. You can't take control of your back without understanding how it's made and its biomechanics, or how it works.

Bones, Discs, Nerves, and All That Stuff

Your back is a complex, intricate mechanism that, besides supporting your head and upper torso, is also vital to many of your body's functions. In an attempt to simplify this anatomy lesson, I have separated the back into four parts: bones, discs, nerves, and muscles and tendons.

The Scoop on Your Back

Bones (spine or vertebrae)

Your spine, or vertebrae, has two basic functions. Together with the muscles and ligaments that surround them, the bones in your back support the upper part of the body. Your spine enables you to stand, walk and move around. The second

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function is to protect the spinal cord, which we will discuss a little later in this chapter.

From the base of your skull to the bottom of your tailbone, you have thirty-three or thirty-four bones everybody knows as vertebrae. The vertebrae is divided into five sections or regions. The mobile part of your spine, or backbone, is comprised of the three upper regions and has twenty-four vertebrae between them. Nine or ten bones in two fused sections make up the two lower regions. Your neck, or cervical region, has seven vertebrae. The mid-back, known as the thoracic or dorsal region (these are the bones attached to your ribs), has twelve vertebrae. Five vertebrae make up the low back or lumbar region, and the two immobile sections are the sacrum and the coccyx (pronounced "cock-six," coccyx is Latin for cuckoo; the coccyx looks like a cuckoo's bill.).

While you were still a fetus, your sacrum had four individual bones, but by the time you were born it had fused into one long single bone. This section of your back forms the back of your pelvis and, unlike the rest of your spine, does not need to be flexible. The coccyx or tailbone has five bones. As you may know, some people have only four coccyx bones. Many evolutionists believe that the coccyx is what's left of the tail we inherited from apes. If this is true, than those of us with five coccyx bones are a somewhat closer relation to our ape ancestors than are those with four.

Again, I want this anatomy lesson to be as painless as possible. But let's lapse into doctor-talk for just a few more seconds. There is really no need for you to learn all the terms such as lumbar and coccyx, except that they are the basis your doctor uses in identifying certain back problems. But if you want to know what your doctor is talking about when he identifies regions of your back with formulas like T₁₂ vertebrae or L₂-L₃ disc, please take a moment to learn this very simple system.

Each vertebrae in your spine is numbered from top to bottom. The bones in the thoracic, for example are numbered T₁, T₂, and so on on down to T₁₂. As you might expect, the vertebrae in the other regions are numbered similarly: C₂, L₁,

The Scoop on Your Back

Anatomy of a disc.¹

etc. Each disc in your spine gets its designation from its location between two vertebrae. The disc between your fourth and fifth thoracic vertebrae, for example, is called your T₄-T₅ disc.

Get the idea? It's easy, isn't it? You should remember, though, that there are no discs in the sacrum.

The vertebrae is a common problem area for back pain. We will look at this important structure in later chapters, especially the chapter entitled "The Causes of Back Pain". Now, let's look at an even more common problem area, the disc.

Discs

All the vertebrae of your spine have a similar structure called facet joints. Facet joints are the hinges on each side of your spine that allow it to move. Between each pair of facet

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joints is a small cushion known in doctorspeak as intervertebral disc. Ingeniously designed, discs have dual functions. They are the bending points in the spine, and they also pad against force.

Intervertebral discs are often called "shock absorbers". This is as good a description as any, as they do operate remarkably similar to the shock absorbers on your car.

For as much trouble as they cause, discs are very simple in structure. They are flat and round and made of a cartilage material similar to rubber. Each disc has a semisolid center consisting of a jellylike matter (i.e. nucleus pulposis) that provides the actual cushioning. The ring of rubberlike cartilage (i.e. fibrosis) supports the soft center and keeps the disc from collapsing.

I will go into discs and the trouble they cause us more extensively in several later chapters. Let's look briefly at the spinal cord and nerves in your back.

Nerves

If your brain is a computer, then your spinal cord is the cable by which the computer sends and receives data from the network. Doctors once believed that the spinal cord was

merely a cable system

The Scoop on Your Back

to get messages to and from the brain. Actually, the spinal cord is an extension of the brain. Through it and the intricate nervous system running throughout your body, messages are constantly being transmitted and received.

The spinal cord itself runs the entire length of the spine. It runs through a special housing, a channel in the center of the vertebrae called the spinal canal. Extending from the spinal cord through small openings between each vertebrae is a nerve, or group of nerves sometimes called a nerve root. In much the same manner as telephone lines branching off to various houses and other structures, these nerve roots branch off to smaller nerve lines into various limbs and other parts of the body.

As you probably already know, nerves are responsible for the sensations your body feels, sensations such as cold, heat pain, etc. What you may not know is that because nerves reach different areas in the body via different nerve roots, problems in certain areas can cause pain in other areas that seem completely unrelated.

For example, nerve roots in your neck come together to form major branches below your shoulders and down into your arms. So, sometimes a problem in your neck can cause pain in your arms. This also can be true with pain in your legs or feet and other parts of your body. This is a phenomenon doctors call root pain. One well-known condition is called sciatica is a phenomenon where pressure on a lumbar nerve or a group of a lumbar nerves that causes pain to travel down the sciatic nerve and into the leg.

There is, of course, a lot more I could say about nerves and the spinal cord, but I'm not too sure the information would help you reach your goal of a better back. Let's move on to spinal muscles.

Muscles and Tendons

Contrary to what you may have heard or assumed, the muscle system in your back does not consist of one gigantic muscle. In fact, from the base of your skull to your pelvis you

Four Weeks To A Better Back 

Posterior Longitudal Ligament

Anterior Longitudal Ligament

The Scoop on Your Back

Cutaway of back muscles.

have many, many spinal muscles. And yes, it is these muscles that come together to give you what is often called a "strong back". It is not, as you will see in a later chapter, only the back muscles that contribute to back strength. Nor are these muscles solely responsible for the fitness of your back.

The muscles in your back support the framework of the spine and provide the means for motion. Back muscles can be the source of several different kinds of back problems. They respond to other problems such as bulging discs or they can develop problems of their own, such as a "pulled muscle", "muscle strain", or "muscle spasms. "

Closely related to your muscles and their functions is another part of the back structure we call ligaments, or tendons. The relationship of muscles and ligaments to back pain will be discussed in the next chapter.

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Your back absorbs about twice as much pressure when you're sitting,

especially if you don't sit properly.

The Scoop on Your Back

How the Back Works

Now that you have a perfunctory understanding of the parts of your back, let's take a look at how these parts work together. Each of the five different sectionscervical, thoracic, lumbar, sacrum and coccyxof your vertebrae have different purposes.

Of these five sections, only the first three play a major role in back problems. The reason for this is primarily because these sectionscervical, thoracic and lumbarsupport and allow for all your back's movement.²

Your Neck (cervical spine)

The cervical spine, or neck, holds up and stabilizes the head. The neck joints are narrow and allow for rational movement. These vertebrae are small and thin. Another important function of the cervical vertebrae is to house the vertebral artery, a critical artery that carries some of the blood supply to the brain.

Even though the only real work your neck should have to do is hold up the head, it can cause serious difficulties if not cared for properly. In a Chapter 6 I will show you several exercises designed for reducing stress in the neck area. You will find these exercise particularly helpful if you spend a lot of time at a desk in front or a typewriter or computer.

2 If you think about it, this makes perfect sense. How often have you heard a product being touted as reliable because it has "fewer moving parts?"

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Your Mid-Back (thoracic spine)

The next section of your spine, the thoracic, supports your ribcage and chest. It is from this region where in a famous story God got the ingredienta ribto create women. The vertebrae here are larger than the bones in your neck. Thoracic vertebrae have a heavy burden; they must support the weight of your neck, shoulders, arms and hands. Besides many other functions, the thoracic vertebrae allow you to move your shoulders. If you participate in activities that require a lot of pivoting, such as, say, golf or racquet ball, you will readily appreciate the importance of this portion of your spine.

Your Lower Back (lumbar spine)

The lumbar is the section of your spine that forms the "S" curve in your lower back. Most of your body's weight is supported by this section of five vertebrae. Even though the lumbar vertebrae are significantly larger than the other vertebrae in your back, they are more likely to cause problems. One of the reasons for this is that the larger joints in the lumbar region cannot rotate easily, making them more susceptible to rotational or twisting injuries.

You Weigh More Than You Think

At least where your lower back is concerned, you do.

Also important to the biomechanics of your back are the discs. Earlier I called these the back's shock absorbers. They are actually more than thatwithout discs the back would not move at all. This is why it is important that we learn to take care of them. The load exerted on each disc in your spine changes drastically with your body movement. Any slight shift in

The Scoop on Your Back

body position can make a tremendous difference.

For example, when you are standing erect the load on the discs in you back is about 100 pounds. As you lean forward, the load increases significantly, more than doubling the pressure the further you lean. Interestingly, the pressure is significantly higher when you are sitting, and it can increase to as much as 275 pounds as you lean forward in your chair. It's no wonder then that people who work in offices have high incidents of back pain.

Something else that might surprise you is that during periods of exercise, unless you are lifting weights or doing some other form of heavy lifting, the pressure on your back is not increased substantially. In fact, you have less pressure on your discs when you are doing situps than when you are slumping forward in a chair.

The spinal cord, muscles and ligaments also play an important role in these biomechanics. All these parts work together, and all are susceptible to extreme pressure. To demonstrate this point further, here's an example:

If you were to lift a ten-pound package from a table, the pressure on your back would be great, but not necessarily harmful. But try lifting the same package with your arms extended and the ratio of pressure on your back can increase by as much as 25 times, applying 250 pounds of pressure on certain discs and muscles in your back. Other positions, such as bending over to pick something up, increase the pressure even more.

Your Back is Not Alone

Luckily, for you and your back, your body is not structured so that your back has to do all its work by itself. In any lifting or other activity that requires you to use your back, other muscles come into play to support and help out. When lifting, for example, the abdominal, or stomach muscles help your back considerably, as do the leg and buttocks muscles.

This seems like a good place to point out the importance of taking care of your muscles and other tissues through proper

Four Weeks To A Better Back

diet, sports and exercise. As I've said, and as you will learn in the following chapters, you really do have a lot of control over the health of your back. Good maintenance practices are essential to a pain free back.