Learning a little about back anatomy can help you manage, or even prevent, back pain.
Almost every American has had at least one bout of back pain. Back pain is the second most common diagnosis after headaches and often leads to missed work and temporary disability.
S.O.S: Save our “S”
The spine is naturally configured in an “S” curve as viewed from the side. A slight inward curve of the neck (cervical spine) gently curves outward at the chest (thoracic) and in again at the lower back (lumbar region). The “S” curving spine is also the most stress-free state. Maintenance of this natural curve is essential to good back health.
Yet, due to the everyday demands of heavy lifting, driving, standing, or sitting at a desk for hours at a time, our spine strays from the comforting “S.” The neck and mid-back suffer as we slouch forward or bend the wrong way repeatedly. One day, our back is abused just once too often. Picking up a crumpled piece of paper that didn’t make it into the trash brings on a sudden twinge of pain.
The back is the spinal vault
Bones called vertebrae surround the spinal cord. The spinal cord carries information about our world and our intentions – both voluntary and automatic – from brain to limbs.
For instance, the index finger tip touches the stove, senses that it’s hot and sends a signal that travels up the median nerve to the group of nerves near the armpit (brachial plexus) to the cervical spine and then to the brain. Our sense of touch is processed and the brain sends an impulse that travels down the spine and out to the body from nerve cell to nerve cell. And in a lightning flash, we withdraw the finger.
A vulnerable vault
The back does a good job of protecting the delicate spinal cord, but is prone to injury. This is because the back must maintain flexibility while providing bony protection for the spinal cord. Bending and twisting of bone over bone is only possible with vertebrae and their supporting muscles and ligaments. These components work together, but each is subject to its own share of problems.
Muscles and ligaments
Back muscles are the most frequently injured structures because they are already working very hard to maintain the “S” curve. Bending too far, or the tendency to overextend with a poor posture, puts more strain on back muscles. In time, whole regions of the back muscles tighten. Continued demand on tight, tired muscles leads to the injury and pain of a muscle strain.
Each vertebra is made up of a body and arch. In the middle of the vertebral body is a spongy central disc that allows for movement of the vertebra above and below. Behind each vertebral body is an arch that protects the spinal cord. Through spaces between each vertebra, spinal nerves exit and each goes to a specific part of the body. Each spinal nerve, except the first, has two nerve roots. One carries messages back from the body to the brain. And the other carries impulses from the brain to the body
In spite of their complex design, the vertebrae cannot handle life’s forces without the help of the back muscles and ligaments. When an area of muscle weakens, the stress is transferred to the closest vertebrae at the ligament, which surrounds the disc. In time, the ligament weakens and the disc slips forward onto the spine or nerve roots.
The spinal cord
All the armor of the vertebrae (bones), muscles, and ligaments serves to protect the spinal cord. The spinal cord is a delicate, whitish-gray vertical tube. It is made mainly of myelin, a fatty substance that insulates nerve fibers. Nerve cells in the spinal cord receive and transmit impulses from the brain and out to the rest of the body and back.