Four separate segments make up your spine. Each has an essential purpose.
Image of spinal segments,

The cervical spine is the first segment of seven vertebrae at the top. It holds your head and neck.

The thoracic spine is the second segment, located in the middle portion of your body. It consists of 12 vertebrae that control the mid-back region.

The five vertebrae of the lumbar spine control the small of your back below the waist. Some people are born with six vertebrae in the lumbar region. This variation has no effect on function.

The sacrum at the very bottom of the vertebrae is a fused segment. This fusion happens before birth. It affects the pelvis and crotch region.
Your back is essential to living well and pain-free. By taking care of your connecting muscles and ligaments, you have a better chance of vertebrae remaining aligned and functional. Here is a list of what can go wrong with your back.

Humans depend on the neck remaining in good condition. When a strong force injures your neck, or if you develop inflammation or degeneration, you will experience pain and perhaps disability.

Younger people usually incur damage caused by an injury. Sports injuries, vehicle accidents, and other blunt-force trauma can cause permanent harm and disability.

Older persons usually have more cases of degenerative disk disability. A lifetime of wear and tear can cause sometimes excruciating, long-term problems. Other common diseases of the neck can produce pain and disability.