The low back is made of up 5 lumbar vertebrae, you sacrum which then connects to your right and left him, so there are a lot of moving joints and structure involved that can be involved with pain. As we move, each joint with either flex, extend or rotate to create motion. Throughout these motions, disks can become pinched, muscles strained, ligaments sprained, etc.
Again, ligaments hold our bones together, so extreme bending, twisting, etc can stretch (sprain) them resulting in back pain and instability. The use of proper body mechanics and ergonomics can help prevent this.
When it comes to the back, we often overlook the importance that muscles play. We consider the disks, the nerves and the bony alignment but can quickly forget that all of those structures are held together and are animated by the network of muscles. If our muscles are weak and/or tight it leads to increased pressure on disks, poor alignment of the vertebrae, increased stress on joints, increased strain when lifting/bending, etc. The better our muscles are, the better our backs become.
When our backs hurt, we become very focused on “the back”; however, the back is greatly supported by the abdominal and hip muscles as well as the hamstrings. As seen in the picture below, there are hip muscles that actually attach to all the low back vertebrae but they attach on the front side. So the weaker the hip and abdominal muscles, the more pain we have in the back. Consider the scenarios of pregnancy and “beer guts”. Both types of individuals commonly complain of back pain, but when we assess their mechanics and body set up, the back pain is resulting from stretched out, weak abdominal muscles which in turn place stress at the back.
The Hamstrings also play a very key role in the health of your back. The hamstrings attach to the bottom of your pelvis and if they are tight directly increase the amount of tension at your low back. This tension magnifies as you twist and bend over which can lead to sprains, strains, disk buldges, herniations, etc.
There are numerous nerves that exit the low back. Nerves emit and pain signal when they are irritated. This can come from increased pressure from muscle tightness, secondary inflammation, a bulging disk, herniated disk, etc. Ultimately the nerve pain is not the problem (however due to the pain it is very problematic!), but is merely the result of something else. An existing body imbalance, etc, led to this condition.
The Sciatic Nerve can be common to back, buttock and back of the leg pain. This is due to where it is located and it’s pathway down the leg to the foot. The sciatic nerve is a large nerve the exists the back, runs down the buttock and back of the leg, then branches into two separate nerves that lead to the foot. Because of its location and pathway it is commonly involved.