In utero, the entire vertebral column has a primary or kyphotic curvature (concave anteriorly) (Figure 1-1C). After birth, with the demands of walking, weightbearing, and gravity, the cervical and lumbar regions form secondary or lordotic curvatures (concave posteriorly) (Figure 1-1D). Primary (kyphotic) curvatures occur in the thoracic and sacral regions, where the vertebrae curve posteriorly. This allows increased space for the heart and lungs in the thorax and birth canal in the sacral region. Lordotic or secondary curvatures occur in the cervical and lumbar regions, where the vertebrae curve anteriorly.
Abnormal primary curvatures are referred to as kyphosis (excessive kyphosis)
, whereas abnormal secondary curvatures are referred to as lordosis (excessive lordosis)
. Patients may present with abnormal lateral curvatures (scoliosis
), which may be due to muscular dominance of one side over the other or to poor posture or congenital problems. To diagnose scoliosis, the physician may ask the patient to bend forward to determine if one side of the thorax is higher than the other due to asymmetry of the spine.