To better understand ankylosing spondylitis, it helps to understand the anatomy of the spine.
The spine is an upright row of stacked bones, called the vertebral column. Individual bones of the spine are called vertebrae. The vertebral column starts under the skull and continues to the buttocks.
Bones of the spine:
The front of each vertebra is a round, solid cylinder of bone. Between each pair of vertebrae, a disk attaches to the bottom of the vertebra above it, and to the top of the vertebrae below it. The discs act as rubber cushions between the vertebrae. In addition, strong ligaments and muscles hold the vertebral column together. These structures support, surround, and protect the spinal cord.
Anatomy of the vertebrae, disks and muscles:
The back of each vertebra is an open ring of bone. Because the vertebrae are stacked on top of one another, the open rings form a tube that surrounds the spinal cord. The spinal cord is a thick bundle of nerves that starts at the bottom of the brain and continues down the spine. The spinal cord carries messages between the body and the brain. Nerves branch off of the spinal cord between each vertebrae.
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