The vertebrae are so articulated that the bodies, transverse processes, and spinous processes are all superimposed. This causes posteriorly two longitudinal grooves, one each side of the spine, in which are placed the longitudinal muscles of the back.

Viewed from the side, it is seen that the column forms a series of curves, slightly forward in the cervical region, markedly backward in the thoracic region, and forward again in the lumbar region. The sacrum, again, is convex backwards, and the junction of the fifth lumbar vertebra with the sacrum is called the sacro-vertebral angle, which is always very marked.

Ossification

Centres for the bodies and neural arches appear before birth. At puberty, epiphyses for the different processes and upper and lower surfaces of the bodies appear. All become completely fused about the twenty-fifth year.