When young the spine is made up of 33 bones stacked one on top of the other until the adolescence. A fully grown adult ends up with 24 bones when the sacral’s bones (5 vertebrae) and the coccyx (4 vertebrae) fuse together.
These remaining 24 vertebrae are classified as follows:
7 cervical vertebrae.
12 thoracic vertebrae.
5 lumbar vertebrae.
There are approximately 220 ligaments, 120 muscles that are related to controlling the motion of the spine.