They are the bones of the spine.
Vertebrae are the pieces of bone that connect chain-like to make up your spine, and the spines of all vertebrate animals. The plural of vertebra is vertebrae, but vertebras is also OK.
Invertebrates.
Cervicle spine has 7; Thoracic spine has 12; Lumbar spine has 5; The Sacrum has 5(fused); and the Coxcyx has 4(Fused). 33. ===
They are the bones that make up the spine.