Anatomy of the Spine

Since so many people suffer the “Back Pain,” let’s start by learning more about the back and spine:

The spine is composed of 24 vertebrae, forming a column. This column, along with the attached muscles, holds the body erect.

The Cervical Spine has seven vertebral bodies that form the neck and hold the head.

The Thoracic Spine has 12 vertebral bodies. These vertebrae have very little motion because they are firmly attached to the ribs and sternum (breastbone). Because there is little motion, this region of the spine is not usually a source of back pain, although the junction between the spine and the ribs (costovertebral junction) can be a source of pain.

The Lumbar Spine has five vertebral bodies that extend from the upper back or lower thoracic spine to the bottom of the spine or sacrum. Because the vertebral bodies of the lower back bear the majority of the body’s weight, and provides great flexibility and movement, most back pain originates in the lumbar spine.

The Sacrum is a triangular-shaped bone and consists of five segments, which are fused together. The sacrum connects the spine to the pelvis.

The Coccyx (also called the tailbone) is located at the base of the spine and is composed of four fused vertebrae. Ligaments attach the coccyx to the sacral hiatus at the synovial sacro-coccygeal joint.

Nerves

Each vertebra has a hole in the center. When stacked on top of each other, they form a hollow tube that holds and protects the spinal cord and its nerve roots. The spinal cord is a large collection of nerve tissue that carries messages from the brain to the rest of the body. Throughout the spinal column, 31 pairs of nerve roots branch out to various parts of the body. These nerve roots exit the spinal column on both sides through spaces (neural foramina) between each vertebra.

Facet Joints

Each vertebra has flat surfaces called facets, which touch where the vertebra fit together. These form a structure called a facet joint on each side of the vertebra. A facet joint is also known as a synovial joint. A synovial joint, such as the knee or elbow, is a structure that allows movement between two bones. The ends of the bones are covered with a material called articular cartilage – a slick spongy material that allows the bones to glide against one another without much friction.

Jelly Donuts?

Disks are cushions in between each vertebrae in the spine. The inter-vertebral disk is comprised of two parts: A tough outer ring-like layer of ligaments called the annulus fibrosis and an inner core of fibers in a gel-like substance known as the nucleus pulposus – imagine a jelly donut. The annular fibers seal in the gelatinous nucleus, and evenly distribute pressure and force from the vertebrae above and below. Each disk is composed of approximately 80 percent water. In order for the disk to function properly, it must be well hydrated. The nucleus pulposus carries the majority of the body’s axial load and relies on its water-based contents to maintain strength and pliability. Each spinal disk has very few nerve endings and no blood supply. Without a blood supply, the disk does not have a way to repair itself, and pain created by a damaged disk can last for years.

As we age, our spinal disks dehydrate and become stiffer, causing the disk to be less able to adjust to compression. While this is a natural aging process, as the disk degenerates in some individuals, it can become painful. The image below shows a herniated disk above a normal disk.

The most likely reason for this pain is that the degeneration can produce micromotion instability and the inflammatory proteins in the soft inner core of the disk can leak out of the disk space and inflame the well-innervated structures next to the disk (e.g. nerve roots). Sometimes a twisting injury damages the disk and starts a domino-effect of events, leading to degeneration and sometimes pain.

All statements, information or opinions provided by this website are provided for educational purposes only. We do not diagnose nor treat through this website or by telephone. As you consider any treatment, discuss them with your physician, or contact Dr. Lox at 727-462-5582.