They allow the vertebrae to be linked like a chain and provide mobile connections between each vertebra. Like other joints in the body, the facet joints can be affected by arthritis. The spinous process is the bone you can feel when running your hands down your back. The paired transverse processes are oriented 90 degrees to the spinous process and provide attachment for back muscles. Though humans are born with 33 separate vertebrae, by adulthood most only have 24.
Physicians use a code to identify the vertebrae.
The seven in the neck are referred to as the cervical vertebrae numbered C1 to C7. They support and provide movement for the head. The thoracic vertebrae numbered T1 to T12, join with and are supported by the ribs, which protect the heart and lungs. Because they are fairly rigid, thoracic vertebrae don't permit much movement and consequently, aren't injured as often as the other vertebrae. The lumbar vertebrae, numbered L1 to L5 are below the thoracic vertebrae and above the sacrum and are most frequently involved in back pain because they carry most of the body's stress.