spine

The human spine (also called backbone or vertebral collumn) usually consists of 33 or 34 vertebrae and 110 joints.
Between these vertebrae are the spinal discs, that work as a shock absorbers by their elastic material.

The spine is usually devided into 5 groups of vertebrae.
From top to bottom:

• 7 cervical vertebrae
• 12 thoracic vertebrae
• 5 lumbar vertebrae
• the sacrum (5 fused vertebrae)
• the tailbone (4 or 5 fused vertebrae)

The most important function of the spine is the protection of the spinal cord.
Humans are unique
The human spine is unique in the fact that is has an S-shape (see for instance the tailbone for a picture). No other animal has a similarly shaped spine, and this gives humans the unique possibility to walk on the hind legs for a longer time. In this configuration, the lumbar vertebrae are most important in absorbing shocks and carrying the weight of the upper body.