The vertebral column plays the most important role in maintaining the posture and contour of the body. It is formed by 26 units called vertebrae. The first vertebra is the atlas and it articulates with the occipital condyles. The vertebral column is differentiated into Cervical (7) vertebrae, thoracic vertebrae (12), lumbar vertebrae (5), sacral vertebrae (5 fused to form 1 bone) and coccygeal vertebrae (4 fused to form 1 bone). In the thoracic and sacral regions, the vertebral column forms a curvature which is convex posteriorly (concave anteriorly) while in the cervical and lumbar region it forms a curvature which is concave posteriorly (convex anteriorly)