One of the most common problems seen in a primary care medical practice is low back pain. It accounts for more discomfort, lost work and productivity, and frustration for many patients than any other malady. Some think it is the price we, as humans, pay for walking upright. The lower back is a complex structure made of bone, muscles, connective tissue and nerves that, along with our legs, hold us erect, allow us to bend, run, twist, catch a football, or just lay down and rest. However, once a problem arises, the complexity of its structure makes pain in the lower back difficult to diagnose and treat.
The lower back consists of a spinal column from the lumbar region of the mid-back down to the tail bone or coccyx. The spinal column consists of 5 lumbar vertebrae which are cylindrical bony structures with a ring like component behind the cylinder also made of bone. In between the vertebrae are disc shaped cushions filled with a gelatinous central core known as the nucleus pulposis (that central core is what commonly "slips out" of the cushion in the case of the infamous "slipped disc"). The lowest lumbar vertebra also known as "L5" sits atop the sacrum which is a large triangular bone just above the central part of the buttocks. Each vertebra and the sacrum have the aforementioned ring of bone behind it, through which the spinal cord traverses and gives rise to nerve roots branching out across the pelvis and lower extremities that allow you to feel and move your lower body. The sacrum and vertebrae are then stabilized by numerous ligaments and muscles. There are many small paraspinal muscles generally traveling up and down the spinal column acting as stabilizers as well as bigger outer muscles one can feel in the lower back that assist in bending, lifting etc. The latter are the muscles that are most commonly injured (or strained) in those "weekend warrior" types who move furniture, lift boxes, bend over and play with their kids, or just "turn the wrong way. Often overlooked, but no less important in stabilizing the back, are the abdominal muscles. They help to counteract the lower back muscles mentioned previously and contribute to good posture. This complex of bone, ligaments and muscles is commonly referred to as the "core".
Problems in the lower back generally occur when one of these structures is injured or deranged in some way. For instance, if the lower back muscles have to carry an inordinate amount of weight either by lifting a heavy object or staying in one position too long, tiny tears occur in those muscles leading to- you guessed it- lower back pain. This often resolves on its own but can be debilitating in the short term. If that nucleus pulposis protrudes through the cushion between 2 vertebrae and pushes on one of the nerve roots leaving the spinal column- you've got severe pain and possibly some numbness or tingling, not only in the lower back, but radiating down one or both legs. If that occurs at the sciatic nerve root, one suffers from the dreaded "sciatica". Moreover, damage to the bony structures themselves from osteoporosis, osteoarthritis or even destruction of the bone by cancer can cause severe pain.