The spine is made up of bones called vertebrae. There are 3 regions, cervical, thoracic, and lumbar. There are 7 cervical bones, 12 thoracic, and 5 lumbar. Above C1 is the skull, and below L5 is the sacrum. There is not a disc between the skull bone and the first cervical bone C1. Between all of the other vertebrae there is a disc between each.
The disc works as a shock absorber and is a cushion between the vertebrae. It works to help with mobility and gives the spine a certain amount of movement in each linear plane. Every disc has a very tough protective outer band; which is called the annulus fibrosis. There are many layers to this and as it moves more towards the center there is the nucleus pulposus. The disc is connected to the vertebrae above and below by something called sharpey’s fibers, which make the connection very strong. They are like little anchors that hold the spine structures together. The disc can herniated up or down into the bone, but this is more rare than a central or lateral posterior herniation. When that happens it is called an endplate herniation, or schmorl’s node.
There is not a direct blood supply to the discs so the only way that they can get nutrients is through motion. The motion is what keeps a disc healthy. When a trauma happens and there is damage done, the area becomes stiff and rigid. The motion stops and the discs become unhealthy. This over time causes what is known as degenerative disc disease.
The spine works as one unit and there are ligaments that are closest to it, then tendons, and then muscles. The cervical discs can become herniated and diseased, but the lumbar region of the low back is where the majority of the problems are. The reason for this is that it is located at the bottom of the spine and has more weight pushing down on it.
