The Shape of the Spine
The normal adult spine is balanced over the pelvis, requiring minimal workload on the muscles to maintain an upright posture. When viewed from the front or back, the normal spine is in a straight line, with each vertebra sitting directly on top of the other. Curvature to one side or the other indicates a condition called scoliosis. When viewed from the side, the normal spine has three gradual curves. These curves help the spine to support the load of the head and upper body, and maintain balance in the upright position. Excessive curvature, however, may result in spinal imbalance.
The Spinal Column
The spinal column is one of the most vital parts of the human body, supporting our trunks and making all of our movements possible. Its anatomy is extremely well designed, and serves many functions, including movement, balance, shock absorption, posture and spinal cord protection.
The spinal column is made up of several parts, including the vertebrae that support the majority of the body’s weight, discs which function as shock absorbers, facet joints that connect the vertebrae, the neural foramen where the nerve roots exit the spine, and spinal cord and nerves. There are also a variety of spinal muscles that connect to the spinal column.
Humans are born with 33 separate vertebrae. By adulthood, we typically have 24 due to the fusion of the vertebrae into the triangular bone at the base of the spinal column. They are comprised of the following:
- Cervical spine: the top 7 vertebrae that form the neck are labeled C1-C7. These vertebrae are responsible for the normal function and mobility of the neck. They also protect the spinal cord, nerves and arteries that extend from the brain to the rest of the body.
- Thoracic spine: the 12 vertebrae that make up the upper back are labeled T1-T12.
- Lumbar spine: the 5 vertebrae that make up the lower back are labeled L1-L5. The lumbar spine bears the most weight relative to other regions of the spine, which makes it a common source of back pain.
- The sacrum and coccyx (tailbone): these 9 vertebrae are fused together to form a solid, bony unit.
All of the elements of the spinal column and vertebrae serve the purpose of protecting the spinal cord, which provides communication to the brain, mobility and sensation in the body through the complex interaction of bones, ligaments and muscle structures of the back and the nerves that surround it. Problems with this complex system can cause pain and even disability.