Lets take a brief section to understand the areas of the spine. The above diagram shows the main regions of the spinal column. The cervical vertebra make up the neck; the thoracic vertebra include the mid-to-upper back, with the shoulder blades on either side; the lumbar spine is the lower back (where many experience back pain). Lower still we have the sacrum - a triangular-shaped bone which forms the back of the pelvis. The coccyx is commonly called the tailbone.
The thoracic spine contains the primary curve of the spine. This is the first curve of the spine in utero. You might imagine the position of the fetus in the womb - the fetal position. Can you envision the primary curve of the thoracic spine?
The cervical and lumbar vertebra make up the two secondary curves of the spine. The cervical curve allows the skull to be buoyant and balanced, while the lumbar curve contains the vertebra that bear the most weight, leaving them more open to wear and tear.