At birth, the spine is straight when viewed from the side (sagittal plane). When the child starts to sit down, the spine drops in a total kyphosis. In addition, the child starts to hold its head up and this leads to formation of the cervical lordosis. Once the child learns to stand up, the lumbar lordosis develops, together with the forward tilting of the pelvis. The thoracic spine remains kyphotic to some degree. In the frontal plane (also known as the coronal plane), the spine should be straight. Limited curvatures and twists are within normal variation and are usually not called pathological.