The Spinal Column.

The spinal column is such an interesting part of human anatomy. I spent about a month learning about it, but I have prepared a nice and short summary of the essentials...

The spinal column is not straight, but is actually "S" shaped. The spinal column is curved in order to be a shock absorber against the force of gravity. It is made of primary (kyphosis) and secondary (lordosis) curves. We are born only with kyphosis curves, but we develop lordosis curves as a result of the force of gravity and our postures.

The spinal column is not the spinal cord but it contains the spinal cord. The spinal column is made of stacked vertebrae (24 functional vertebrae, but actually 33 in total, but that's another story). There are four types of vertebrae: cervical, thoracic, lumbar, and sacral (with cervical vertebrae being stacked right below the head and with sacral vertebrae being located in the lowest part of the back). The vertebrae for each of these types are shaped differently and have different roles. The vertebrae (more specifically, the superior and inferior articular facets) determine what kind of movement the different parts of the spinal column can preform. If you stand up right now and move around a little, I bet you can guess what kind of movements cervical, thoracic, and lumbar vertebrae allow. How much can you move your neck? Quite a lot. This is because the articular facets of the cervical vertebrae are almost flat so they allow for movement in all directions. On the other hand, try moving your chest region (i.e. where the thoracic vertebrae are located). Your chest region can rotate side-to-side, but no matter what you do, you can't (and you wouldn't want to!) bend your chest in half. This type of movement is controlled because the articular facets of the thoracic vertebrae are positioned frontal, which allows rotation, but not bending (i.e. flexion and extension). Lastly, can you rotate your lower back? Nope. If you try, you end up moving your upper chest (which is what can rotate) or your hips and not the actual lower back region. The type of movement allowed in the lumbar (lower back) region is bending (forward and backward or flexion and extension). The articular facets of the lumbar vertebrate are positioned medially.