The vertebrae support the majority of the weight imposed on the spine. The body of each vertebra is attached to a bony ring that consists of several parts. A bony projection on either side of the vertebral body called the pedicle supports the arch that protects the spinal canal. The laminae are the parts of the vertebrae that form the back of the bony arch that surrounds and covers the spinal canal. There is a transverse process on either side of the arch where some of the muscles of the spinal column attach to the vertebrae. The spinous process is the bony portion of the vertebral body that creates the "bumps" you feel down the center of your neck and back.
In between the vertebrae are discs that function as shock absorbers and as joints. They are designed to absorb the stresses carried by the spine while also allowing the vertebral bodies to move with respect to each other. Each disc consists of a strong outer ring of fibers called the annulus fibrosis and a soft, gel-like center called the nucleus pulposus. The annulus helps keep the disc's inner layer intact and is made up of very strong fibers that connect each vertebra together. The nucleus has a high water content, which keeps it very moist.
The facet joints connect the bony arches of each vertebral body. There are two facet joints between each pair of vertebrae, one on each side. Facet joints connect each vertebra to the one above and below it, and are designed to allow the vertebral bodies to rotate with respect to each other.
The neural foramen is the opening where the nerve roots exit the spine and travel to the rest of the body. There are two neural foramina (the plural of foramen) between each pair of vertebrae, one on each side. The foramen creates a protective passageway for the nerves that carry signals between the spinal cord and the rest of the body.
The spinal cord extends from the base of the brain to the area between the bottom of your first lumbar (low back) vertebra and the top of your second lumbar vertebra. The spinal cord ends by dividing into individual nerves that travel out to your lower body and your legs. This cluster of nerves at the end of the spinal cord is called the cauda equina, the Latin name for "horse's tail." The nerves travel a short distance through the spinal canal before they exit the neural foramina.
The spinal cord is covered by a protective membrane called the dura mater, which forms a watertight sac around the spinal cord and nerves. Spinal fluid inside the sac surrounds the spinal cord.
The nerves in each area of the spinal cord connect to specific parts of the body. The nerves of the cervical spine go to the upper chest and arms. The nerves also carry electrical signals back to the brain, creating sensations. Damage to the nerves, nerve roots or spinal cord can lead to symptoms such as pain, tingling, numbness and weakness.
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