The spine (backbone) is composed of 33 interlocking bones called
vertebrae that are separated by soft, compressible discs and supported by many
different ligaments and muscles. It is divided into five segments: cervical
(neck), thoracic (upper and middle back), lumbar (lower back), sacrum (pelvis),
and coccyx (tailbone). In each segment, the vertebrae are numbered from top to
bottom. For example, a C3 is the third vertebra in the neck area, while a T6 is
the sixth vertebra in the thoracic area.
The vertebrae in the spine normally form three curves. These curves allow
the spine to absorb shock as you move.
ByHealthwise Staff Primary Medical ReviewerWilliam H. Blahd, Jr., MD, FACEP - Emergency Medicine Specialist Medical ReviewerRobert B. Keller, MD - Orthopedics