The Spinal Column is also called the vertebral column. The bones in the spine are called vertebrae. The column starts at the base of the skull and continues to the pelvis. Alternate layers of bone (vertebrae) and cartilage (the intervertebral discs) stack vertically one on top of the other in the spinal column. The lattice-like structure of the cancellous bone (the spongy interior) in a vertebra absorbs external pressure.
The cartilaginous discs between vertebrae absorb and distribute shock and keep the vertebrae from grinding together during movement.
You can see the 4 regions of the spine below in the illustration.
If you want to learn more about the thoracic spine specifically, read our in-depth article about upper back anatomy.
The spine has four natural curves that you can see in the above picture on the left. Two are lordotic and two are kyphotic.
The cervical and lumbar curves are lordotic; they curve out.
The thoracic and sacral curves are kyphotic; they curve in.
The spinal curves help to distribute mechanical stress as the body moves; they help you move safely.
The cervical spine is your neck, and it has 7 vertebrae.
The thoracic spine is located in the chest area and contains 12 vertebrae. The ribs connect to the thoracic spine and protect many vital organs.
Learn what conditions can affect your thoracic spine in our Upper Back Pain Center.
Next is the lumbar spine. Most people have five lumbar vertebrae although it is not unusual to have six. The lumbar vertebrae are larger than the cervical or thoracic as this spinal region carries most of the body's weight. The sacrum and coccyx are uniquely shaped.
Medical professionals often abbreviate the levels (vertebrae) of the spinal column. For example, the seven cervical vertebrae are C1, C2, C3, C4, C5, C6 and C7.
The thoracic levels are T1 through T12.
Similarly the lumbar levels are L1 through L5 (or L6). The sacrum is simply S1. The coccyx is not abbreviated or numbered.
With the exception of the atlas, axis, sacrum and coccyx, each cervical, thoracic, and lumbar vertebra is similarly shaped.