In order to better understand the most common injuries and diseases of the spine, it is essential to have a fundamental understanding of spine anatomy and its role in the body. The human spine is a remarkable structure and it performs a number of important functions:
It provides protection for the spinal cord
It provides the support needed to walk upright
It allows the torso to bend and twist
It supports the head and allows movement from side to side and up and down
The spine is made up of a column of 26 bones that extend in a line from the base of the skull to the pelvis. Twenty-four of these bones are called vertebra (plural – vertebrae). When viewed from the side, the spine has a natural "S" curve.
Cross Section of a Vertebra
The spinal cord travels from the brain through the entire length of the spine. Nerves branch out from the spinal cord all along its course. The nerves that exit C1 through C7 take care of everything that is going on in the face, eyes, ears, shoulders, hands and fingers. The nerves exiting the thoracic vertebrae (T1 to T12) look after the GI tract, the liver, ureters, some of the colon and the blood vessels in the abdomen. Those nerves leaving the spinal cord at L1 through L5 take care of the colon and the rectum, as well as the blood vessels in the legs, feet and toes.
Structures of the Spine
In addition to the vertebrae, there are a number of structures and features of the spine that are important to understand:
Intervertebral Discs (Discs)
– pads of cartilage between vertebrae that act as shock absorbers.
– joints located on both sides and the top and bottom of each vertebra. They connect the vertebrae through which the nerves leave the spine and extend to other parts of the body.
– an opening between vertebrae through which the nerves leave the spine and extend to other parts of the body.
– elastic bands of tissue that support the spine by preventing the vertebrae from slipping out of line as the spine moves. A large ligament often involved in spinal stenosis is the ligamentum flavum, which runs as a continuous band from lamina to lamina in the spine.
– part of the vertebra at the upper portion of the vertebral arch that forms the roof of the canal through which the spinal cord and nerve roots pass.