Axial skeletal system is the main structural foundation of human body. It plays a pivotal role in giving upright posture and body shape by anchoring limbs and other organs.
Axial skeletal comprises of skull, face,vertebral column, sternum and 24 ribs.
But vertebral column is the main structure that gives flexibility to the whole body thanks to different curves of the different regions of the spine.
CURVATURE OF SPINE
We all might have seen adverts of sleeping mattresses that shows body contours adjusting to the mattress, Insisting consumers to purchase it because it is body posture friendly.
As human beings we are having twoprimary and two secondary curves.
As a new born child, human beings have only one curve as a whole that is called primary curve. Remember the picture of foetus with “C” Shaped curve. The convexity of such curve is posterior. Hence also known as KYPHOTIC CURVES. Thoracic and sacral region retains this curve.
However, as child grows and starts lifting his head and eventually bearing weight on his feets, the secondarycurves that has convexity anteriorly starts taking shape. Also called as ANTERIOR CURVES or LORDOSIS.Cervical and lumbar region curves falls into this category. It is important to note that lordotic curvature at the cervical region starts developing at the age of around three months when child starts lifting his head. But lumbar curve develops little late when child begins to sit up and walk usually at the age of 6 to 8 months.
FUNCTIONAL IMPORTANCE OF SPINAL CURVES.
- The curvy shape of the spine helps vertebral column to absorb axial compression load more efficiently than that of a straight rigid spine.
- The curves having added flexibility helps to withstand the forces of gravity and other external forces. Hence acting as a dampner.
IMPORTANT THINGS TO REMEMBER
The junction between these curves are area of greater force concentration and hence susceptible for injuries. THESE TRNASITIONAL ZONES ARE AT CERVICOTHORACIC AND LUMBO SACRAL REGION.
Also these two regions are the most flexible regions and majority of degree of motion occurs at these regions.
Anterior concavity of thoracic spine places the center of gravity of head and cervical spine anterior to much of the thoracic spine and hence produces flexion moment at the thoracic region.
In older age secondary curves begin to disappear because of disc degeneration and osteoporosis and vertebral wedging. Hence creating imbalance in transmission of axial forces.
The spine as whole is supported by different ligaments and vertebrae are aligned to the natural curve.
If we want to compare different regions of the spine, it is lumbar region that has the maximum load bearing function and hence lumbar vertebrae are slightly larger in shape to fulfills its duty.