When an individual suffers from back pain, the physician's focus is on a spinal segment.
The lower back is called the lumbar spine and is made up of five vertebrae and the sacrum. The middle of the back is the thoracic spine and has 12 vertebrae, and the neck is the cervical spine, with seven vertebrae. Vertebrae are the bones of the spine. They provide both support and protection for the spinal cord. An intervertebral disc sits between vertebrae and connects the vertebrae.
An intervertebral disc is a large, round ligament. If you look at a cross-section of the intervertebral disc, you will see that it is made up of two parts. The outer ring is the annulus, which is the strongest part and is responsible for connecting the vertebrae. The inner area is the nucleus pulposus, which is soft and has the consistency of crabmeat. The nucleus pulposus acts as the shock absorber for the spine.
The nerve roots carry information back and forth between the extremities and the brain. The nerve roots can cause pain when they are irritated or pinched by the disc or bone spurs.