Vertebrae
Cervical (neck) - the main function of the cervical spine is to support the weight of the head. The seven cervical vertebrae are numbered C1 to C7. The neck has the greatest motion because of two specialized vertebrae that connect to the skull. The first vertebra (C1) is the ring shaped that connects directly to the skull. This joint allows for the nodding motion of the head. The second vertebra (C2) is the peg-shaped.. This joint allows for the side-to-side motion of the head.
Thoracic (mid back) - the main function of the thoracic spine is to hold the rib cage and protect the heart and lungs. The twelve thoracic vertebrae are numbered T1 to T12. The range of motion in the thoracic spine is limited.
Lumbar (low back) - the main function of the lumbar spine is to bear the weight of the body. The five lumbar vertebrae are numbered L1 to L5. These vertebrae are much larger in size to absorb the stress of lifting and carrying heavy objects.
site: http://www.mayfieldclinic.com/PE-AnatSpine.htm#.VmcQD3arTIU