First, I would like to say a few words about the spine! The spine or also called the vertebral column or spinal column is composed of a series of bones called vertebrae stacked one upon another. There are four regions of the spine:cervical (neck); thoracic (chest/trunk); lumbar (low back) and sacra (pelvic).
You should also know that the cervical spine is made up of seven cervical vertebrae. The main function of the cervical spine is to support the weight of the head which is approximately 10-12 pounds. The cervical spine has the greatest range of motion, in part because of two specialized vertebrae that move with the skull.
Cervical vertebrae are the smallest of the vertebrae. The first cervical vertebra is called the atlas and is significantly different from the other vertebrae. It is ring-like in shape with two large protrusions on the sides to support the weight of the head.
The second cervical vertebra is called the axis. The axis is also unique in that it has a bony peg-like protrusion, called the dens or odontoid on its upper surface that fits within the ring of the atlas. The curve of the neck is described as a lordosis curve, and looks like a “C” in reverse.
The main function of the thoracic spine is to protect the organs of the chest, especially the heart and lungs. There are 12 thoracic vertebrae with one rib attached on each side, to create a thoracic cage, which protects the internal organs of the chest. The thoracic spine has a normal kyphosis, or “C” curve.
The thoracic spine is less mobile than the cervical and lumbar spine because of the thoracic cage. And finally – the lumbar spine has five lumbar vertebrae, which are the largest vertebrae. These vertebrae are also aligned in a reverse “C” like the cervical spine, creating a normal lumbar lordosis. The five lumbar vertebral bodies are the weight-bearing portion of the spine and are the largest in diameter compared to the thoracic and cervical vertebral bodies.