The four adult curvatures are classified as either primary or secondary curvatures. Primary curves are retained from the original fetal curvature, while secondary curvatures develop after birth.

What are primary curvatures?

Anatomical Parts

The thoracic and sacral (pelvic) curves are termed primary curvatures, because they alone are present during fetal life.

Which curvatures develop first?

Of the two secondary spinal curves, the cervical curve of the neck region is the first to develop. Within the first few months of life, as the infant develops sufficient strength and coordination to hold his head up, the cervical curve begins to develop.