We need a cursory understanding of the spine – its alignment, its motions, and the different types of loads and stress we place upon it.The spine is a series of curves. As babies, we all start in a position of flexion which is called our primary curve.
As we grow, we start to develop secondary curves, or a lordosis, in the lumbar spine and neck. If you’re a visual person, think about when a baby is laying on their stomach and wants to look up to see mommy or daddy. They have to extend their neck to do this.
So we essentially have four different curves or sections of our spine:
• The cervical spine (lordosis). There are seven cervical vertebrae
• The thoracic spine (kyphosis). There are 12 thoracic vertebrae
• The lumbar spine (lordosis). There are five lumbar vertebrae
• The sacrum and coccyx (kyphosis)
Vertebrae are the bones that make up your spinal column.
The front part of a vertebrae is called the body. Behind the body is the intervertebral foramen, which houses your spinal cord. The back part of your vertebrae has numerous bony prominences. Extending from the back is your spinous process, and to the sides you have your transverse processes. The transverse and spinous processes are attachment points for various muscles of the back
In between each vertebrae, you have what’s called an intervertebral disc. These are there not only for shock absorption, but perhaps more importantly for increasing range of motion. If the spine were simply a series of vertebrae stacked on top of each other, range of motion would be incredibly limited
A disc can be thought of as a marshmallow with a jelly filling.
Movements of the Spine
There are four primary movements of the spine. While many of these motions aren’t pure (they are actually combinations of two or more motions), I really don’t think we need to get that specific for this particular article.
The four movements of the spine are:
• Spinal flexion, or forward bending.
• Spinal extension, or backward bending
• Lateral flexion, or side bending.
• Spinal rotation, or rotating your spine to one side or the other.
When it comes to the spine and the anatomy involved, each area or section of the spine is built a little bit differently. If you examine how each section of the spine is built, it will give you a little insight as to what movements it will be best (or worst) at.
The cervical spine according to the joint-by-joint is a mix of mobile and stable segments. The lower cervical spine (C3-C7) should be stable, while the upper cervical spine (C1 and C2) should be mobile. The cervical spine is also fairly balanced in its ability to flex, extend, side bend and rotate.
The thoracic spine has direct attachments to the rib cage, making it’s ability to flex and extend quite very poor. However, that doesn’t mean it shouldn’t move at all!
The thoracic spine actually has the most rotary capacity per segment (typically 7-9 degrees), which adds up to over 70 degrees of total rotation!
Finally, the lumbar spine is primarily built for flexion and extension, and according to the joint-by-joint its focus should be on stability. While it does have some rotary capacity (0-2 degrees per segment), it’s definitely not as “rotation friendly” as the thoracic spine is.
Panjabi (1) introduced the concept of a “neutral zone” for your spine.
Quite simply, there is a zone where you should keep your spine that is within normal (neutral) limits, and the further you move away from that position, the more likely you are to get injured.
This is important to mention, as researchers such as Stuart McGill have noted that while you can injure your back at any point in time, you’re more likely to do so at the end ranges of motion. The most specific example would be if you tried to lifting something from full lumbar flexion. So we’ve covered your spinal anatomy and the motions you have available to you