Physiology For Dummies
I had been an athlete in competition for some 20 years. I was pre-med and went into psychology before finding myself in computers, so I am uniquely situated to comment on this area.
First, a bit of American history: for a long time, only neurosurgeons were allowed to handle back problems. This began to change only as late as nineteen sixty-nine or so when a neurosurgeon gave up his specialty to form the first clinic to handle back problems exclusively. He found, going into the seventies and eighties, that surgery was contraindicated for a majority of the back sufferers and, in fact, a substantial number of those who did get surgery NEVER got better and ALWAYS required TWO operations even if successful.
The Bones Of the Back
Now, lets depart a moment from this discovery, or series of discoveries, and look at the human spine. The spine is about two and a half feet long, from stem to stern in almost all individuals, including your cousin with the pencil neck, Spiny Norman, and features 23 bones called vertebrae in all peoples. Your cousin Spiny Norrman at six two of malnourished height APPEARS to have an elongated neck because of an overlarge larynx, due perhaps to thyroid deficiency, and the depression of the rib cage. Yes, the ribs at the top have been pressed down to show more of what would have been hidden by deltoids, maseter muscles etc. Everyone has the same number of vertebrae and they are all more or less congruent with each other. But during childbirth, sometimes overzealous doctors PULL on the head of the emerging fetus, which causes the ribcage to permanently compress. And create neck pains later on.
In a normal spine, there are three visible, natural curves front to back which assist load -bearing tasks. There should be no curves at all going side to side. The structure has no real rigidity -- posture and curves are maintained primarily by the supporting muscles and by the rib-cage.
The spine actually has, practically speaking, only three bendable points (neck, lower back, and "hips") and, considering the realities of normal movement, only two as far as we are concerned, even though there are seven vertebrae at the neck and five or so at the lower back. Why is this? Well, the ribcage prevents significant movement to some degree in the thoracic, or mid section, leaving the neck and the lower back as high stress points.
The most common problem is lower back pain, and of the gamut of problems here, the most common diagnosis appears to be Level I-II Lumbar-Sacral Strain. The next most frequent problem involves spinal disk problems ranging from moderate bulging to full rupture. Causes range from athletic injury to long-term cumulative effects of poor posture, work ergomics, misalignment featuring unequal leg length and hip torsion.
Looking at the lumbar vertebae we see the most massively constructed spinal bone. It’s a solid chunk with very thick blade-like processes offering attachments to some of the most powerful muscles in the body. These "processes", or bone extensions also offer the path along which major nerve roots exit the spinal cord. No wonder that backpain from muscular insult produces sympathetic pain as well in other parts of the body.
The dark, bean shaped hollow you see in the diagram holds the jelly-filled disk that cushions the vertebrae from grinding against each other. This disk is built like an onion or a tree-trunk, with layers of laminate tissue wrapping the gunk that does the shock-absorbtion work. The disk bulges when some of these internal laminations begin to break down.
Damage due to sudden trauma, including tears, extrusions, disk inflammations, lacerations and bone- breaks are a whole world unto themselves. This discussion will limit itself to the more common chronic conditions.
Muscles
There are four layers of muscle groups that control the lower back directly. In addition to these, the abdominals help stabilize posture and the larger muscle groups of the thighs and buttocks help relieve back stress in the way they allow lifting movement. Not shown in the diagram depicting three layers are the erector spinae, which run parallel on both sides of the vertebral column from neck to sacrum.
The main thing to note here is the way everything interlaces, such that movement of un-injured parts can cause stress to unrelated areas that have suffered damage.
Nerves
As the spinal cord travels along its path from head to the sacrum, nerve roots snake out from the bony protection of the spine along the spinal processes. The nerves branch and rebranch outward, sometimes forming dense clumps called plexus, ganglia or node, depending on the size and density. In the lower back, the nerves that control the legs and lower functions fan out in the shape of a mare’s tail, and among these nerves is the infamous sciatic nerve that wraps around the back of the leg to the front of the knee – more or less.
As you can see from the diagram, the sciatic nerve loops over and under various VERY active muscle groups.
Press the nerve at any point and you can have pain anywhere along its length. Lower back pain is seldom limited to just the lower back region for this reason. When a muscle receives an "insult" for any reason, tissues swell with natural cushioning fluid, blood rushes to the area packing the local capillary net increasing the swell and a number of chemical and unicellular defenses come into play as well. The "bad disk" you hear about produces pain through pressure on the spinal cord itself. The drawing above is a much simplified depiction of just one of the nerve nets in the lumbar region.
As a side note here, people who suffer paralysis do not usually have a "severed" spinal cord from the actual injury ; the condition comes from the body’s reaction to injury causing a worse situation than the injury had caused, as in the case of Steve Reeves, the actor who portrayed Superman. When a fracture occurs white blood cells rush to the area and attack everything, including the nerve tissue of the cord itself.
In lesser injuries, as with back strains, the injured muscles swell, putting pressure on nerves and causing the pain to radiate outward and sometimes far away from the actual site of injury. When the disk "bulges", the disk material causes pressure on the nerve directly or causes other things in the compact area of the back to shift and press nerves indirectly.
Now, keep in mind that the nervous system is incredibly complex. Neuro specialists comprise the highest level of I.Q. pool among primary care providers, and we STILL do not know most of the basic how and why of the human nervous system.
Some of you who have not yet had back pain, will say, "Oh this is all exaggerated stuff. How come this sounds so NEW? How come people didn’t have this problem before?" Well, the answer is that pain caused by lower back problems is nothing new; in the past, people called it "lumbago" or "chilblaines" or misdiagnosed the case as one of "gout". In those days they did what they do today: they kicked back by the fire and chilled out for a while.
Full recovery in the best of cases can take months or years. And that’s without surgery.
Island Life
Living With Back Pain © 2000 -