VERTEBRAL COLUMN

Your vertebral column consists of 33 pieces divided into three different categories.  There are 24 vertebrae on the average human skeleton (C1 being at the top, C7 connecting with T1, T12 connecting with L1 and L5 being at the bottom).

CERVICAL VERTEBRAE First, the cervical vertebrae make up your neck region. There are 7 cervical vertebrae (C1 to C7). C1 (called the Atlas) articulates with the occipital bone. This is where your skull attaches with the rest of your skeleton. The Atlas rotates on C2, which is referred to as the Axis and this relationship allows you to turns your head from side to side.

THORACIC VERTEBRAE Second, there are the thoracic vertebrae. There are 12 thoracic vertebrae (T1 to T12) that can be thought of as your midback back region.  The ribs connect with the thoracic vertebrae.

LUMBAR VERTEBRAE Thirdly, there are the lumbar vertebrae. There are 5 lumbar vertebrae (L1 to L5), and this area can be thought of as your lower back. They are the largest of the three types of vertebrae.

SACRUM Also part of the vertebral column is the Sacrum. The sacrum consists of 5 bones (S1 to S5), that fuse to form the whole sacrum, which articulates with the innominate bones of the pelvis. The top part of the sacrum articulates with L5. COCCYX The coccyx (the coccygeal vertebrae). This is commonly called the tail bone. There are 1-4 bones that fuse together to form the coccyx, which articulates with S5 of the sacrum.

Reference

Tim D. White, 1991. Human Osteology

White, Tim D. and Pieter A. Folkens, 2005. The Human Bone Manual. Elsevier

http://www2.ma.psu.edu/~pt/renee384/anatomy.htm