In the womb and for a period of time following birth, a baby's spine is shaped like the letter C. This curve is termed a primary curve, which is Kyphotic. During the time the baby is learning to lift his head and eventually walk, muscles develop. As muscular strength and ability is gained, the baby's activity will shift body weight to the spine. Gradually secondary curves develop in the cervical and lumbar regions; Lordotic curves. These curves will continue to develop until growing stops.

Spinal curves are either kyphotic or lordotic. In a normal spine there are four types of spinal curvatures important to balance, flexibility, and stress absorption and distribution:

Type of Spinal Curves	Curve Description
Kyphosis or Kyphotic Curve	Concave anteriorly and convex posteriorly
Lordosis or Lordotic Curve	Convex anteriorly and concave posteriorly
Curvature	Normal Curvature
Cervical Lordosis	20 to 40 degrees
Thoracic Kyphosis	20 to 40 degrees
Lumbar Lordosis	40 to 60 degrees
Sacral Kyphosis	Sacrum fused in a kyphotic curve