Thoracic Spine Anatomy

Cervical Spine (Neck)

The cervical spine is made up of the first seven vertebrae in the spine. It starts just below the skull and ends just above the thoracic spine. The cervical spine has a lordotic curve, a backward "C"-shape-just like the lumbar spine. The cervical spine is much more mobile than both of the other spinal regions. Think about all the directions and angles you can turn your neck.

Unlike the rest of the spine, there are special openings in each vertebra in the cervical spine for the arteries (blood vessels that carry blood away from the heart). The arteries that run through these openings carry blood to the brain.

The top two vertebrae in the cervical spine, the atlas and the axis, differ from the other vertebrae because they are designed specifically for rotation. These two vertebrae are what allow your neck to rotate in so many directions, including looking to the side.

The atlas is the first cervical vertebra-the one that sits between the skull and the rest of spine. The atlas does not have a vertebral body, but does have a thick forward (anterior) arch and a thin back (posterior) arch with two prominent sideways masses.

The atlas sits on top of the second cervical vertebra, the axis. The axis has a bony peg called the odontoid process, which sticks up through the hole in the atlas. It is this special arrangement that allows the head to turn from side to side as far as it can. Special ligaments between the atlas and the axis allow for a great deal of rotation.

The cervical spine is very flexible, but it is also at risk for injury from strong, sudden movements, such as whiplash-type injuries. There is limited muscle support in the cervical area. The head weighs about 12 to 15 pounds and is balanced on top of the atlas bone at the top of the spine. Sudden, strong head movements can cause damage.

Lumbar Spine (Low Back)

The lowest part of the spine is called the lumbar spine. This area usually has five vertebrae. However, sometimes people are born with a sixth vertebra in the lumbar region. The base of your spine, called the sacrum, is a group of specialized vertebrae that connects the spine to the pelvis. When one of the bones forms as a vertebra rather than part of the sacrum, it is called a transitional (or sixth) vertebra. This occurrence is not dangerous and does not appear to have any serious side effects.

The lumbar spine's shape has a lordotic curve, shaped like a backwards "C". If you think of the spine as having an "S"-like shape, the lumbar region would be the bottom of the "S". The vertebrae in the lumbar spine area are the largest of the entire spine. The lumbar spinal canal is also larger than in the cervical or thoracic parts of the spine. The size of the lumbar spine allows for more space for nerves to move about.

Low back pain is a very common complaint for a simple reason. Since the lumbar spine is connected to your pelvis, this is where most of your weight bearing and body movement takes place. Typically this is where people tend to place too much pressure, such as lifting up a heavy box, twisting to move a heavy load, or carrying a heavy object. Such repetitive injuries can lead to damage to the parts of the lumbar spine.