The Parts of a Healthy Spine
Your spine is made up of different bones which work together to form joints so you can perform different movements. The bones and joints that make up your spine include:
- Body. The body is the front portion and the main weight-bearing structure of the vertebra.
- Spinous process. The spinous process is the posterior, or rear, portion of the vertebra. It is the bony ridge you can feel down your back.
- Laminae. These are two small plates of bone that join in the back of the vertebra.
- Pedicles. Pedicles are short, thick bumps that project backward from the upper part of the vertebral body.
- Transverse processes. These are the bony projections on either side of the vertebra where the laminae join the pedicles. Muscles and ligaments attach to the spine on the transverse processes.
- Facet joints. These are the spinal joints, the areas on the spine where one vertebra comes into contact with another.
Joints allow for movement, since bones themselves are too hard to bend without being damaged. Facet joints are the specialized joints that connect the vertebrae. The facet joints allow the vertebrae to move against each other, providing stability and flexibility. These joints allow us to twist, to bend forward and backward and from side to side. Each vertebra has two sets of facet joints. One pair faces upward to connect with the vertebra above, and the other pair faces downward to join with the vertebra below.
In the center of each vertebra is a large opening, called the spinal canal, through which the spinal cord and nerves pass. The vertebrae are held together by groups of ligaments (fibrous tissues that connect bone to bone).
Intervertebral discs are flat, round cushioning pads that sit between the vertebrae and act as shock absorbers. Each intervertebral disc is made of very strong tissue, with a soft, gel-like center — called the nucleus pulposus — surrounded by a tough outer layer called the annulus. When a disc breaks or herniates (bulges), some of the soft nucleus pulposus seeps out through a tear in the annulus. This can result in pain when the nucleus pulposus puts pressure on nerves.
The spinal cord, the column of nerve fibers responsible for sending and receiving messages from the brain, runs through the spinal canal. It is through the spinal cord and its branching nerves that the brain influences the rest of the body, controlling movement and organ function.
As the spinal cord runs through the spinal canal, it branches off into 31 pairs of nerve roots, which then branch out into nerves that travel to the rest of the body. The nerve roots leave the spinal cord through openings called neural foramen, which are found between the vertebrae on both sides of the spine. The nerves of the cervical spine control the upper chest and arms. The nerves of the thoracic spine control the chest and abdomen, and the nerves of the lumbar spine control the legs, bowel and bladder.
Tendons connect muscles to bone and assist in concentrating the pull of muscle on bones. Ligaments link bones together, adding strength to joints. They also limit movements in certain directions. Muscles provide movements of the body and help maintain position of the body against forces such as gravity.