As a vital part of the human body, the spinal column allows for a host of different functions to occur, including the basic abilities of movement and balance. It also allows us to keep ourselves upright in posture and helps protect the spinal cord from injury and damage.
In protecting the spinal cord as it communicates with the brain, the spinal column is composed of many different parts. These parts, which the include the vertebra, help the body manage the myriad bones, ligaments and muscle structures that send physical sensations throughout the body via a complicated network of nerves supported by bones, ligaments and muscle structures.
Composition of the spinal column
The spinal column is made up of 33 different bones, or vertebrae, that are grouped into five distinct categories: thoracic, cervical, lumbar, sacrum and coccyx.
The thoracic portion is located between the cervical and lumbar sections at chest level. Labeled T1 through T12, they serve as rib cage attachments. The cervical section is comprised of seven vertebrae at the top of the spine, denoted as C1 to C7, and this is the part of the spinal column that is connected to the base of the skull. The cervical section gives us mobility and neck movement while protecting the vital pathways moving from the brain to the rest of the body.
Located between the thoracic and sacrum areas, the lumbar vertebrae (L1-L5) bear the weight of the spinal column. The sacrum, found at the very bottom of the spine, has five separate sections fused together, known as S1 to S5. It’s here that the pelvis connects to the spinal column.
And lastly, the coccyx is the last and bottommost portion of the spinal column, comprised of four vertebrae that, like the sacrum, are fused together.
In the normal human body, the spine appears as a straight line but does in fact have gentle curves, which can be seen when viewed from a certain angle. One such gentle bend—known as the lordotic curve, meaning it moves inward— can be seen in the neck and lumbar portions of the spine. If a curve moves outward—as it does in the thoracic part of the spine—it’s known as kyphotic.
These natural spinal curves keep our bodies erect and give us balance while also helping to support the weight of our heads and upper bodies. Occasionally, however, when the spine has too great an amount of curve, conditions can occur that limit mobility and very often cause pain.
Because the spine is located above the pelvis, our bodies don’t incur strain when we stand upright. But when problems cause the spine to be out of this optimal and normal position, the muscles can be stressed and abnormalities in the spinal column can occur, leading to disabilities.
The Parts of the Spine: A Glossary
- The spinal cord contains nerves and pathways that carry signals from throughout the body to the brain.
- As signal transmitters, nerve roots move information between the spinal cord and other parts of the body.
- The vertebral body is cylinder-shaped and bears the weight of the vertebrae.
- Creating the outer wall of the vertebral canal, the lamina—a series of flat plates—help protect the spinal cord.
- The vertebral canal is a channel made up of the vertebral body and the lamina—this is where the spinal cord sits.
- Pedicles act as connectors between the lamina and the vertebral body.
- As separators of the vertebrae, discs are comprised of a durable elastic material that allows the spine to move naturally.
- The point at which two vertebrae attach is known as an articular facet.
- Protruding from the back of each vertebra, the spinous processes support the muscles and ligaments that move and hold the vertebrae.
- Protruding from the sides of each vertebra, the two transverse processes also stabilize muscles and ligaments.
Nervous System Anatomy
Whereas all the components of the spinal column and accompanying vertebrae protect the spinal cord from injury or damage, the spinal cord itself interacts with the ligaments, bones and various muscle structures of the back and surrounding nerves to create sensations throughout the body that allow for mobility. At the L1 level the spinal cord ends, splitting into a nerve root bunch called cauda equina (“horse’s tail) that travels down to the lower body and legs.