Human spine or vertebral column is a structure made of multiple small units called vertebra and extends from just below the base of skull to a point jut below the beginning of gluteal cleft. You can palpate the lower part by following the spine till its lower end.
A vertebra is smallest unit of vertebral column. Plural term is vertebrae. Vertebrae have been modified according to the function they are expected to serve in different parts of spine.
To a naked and unaccustomed eye, the spine appears as a straight column. But that is not the case. Spine appears straight in antero-posterior view (That means looking from front or back) but in lateral view or looking from a side, we can see multiple curves in the spine in different regions.
These curves are called kyphotic if they are concave in anterior(front) and convex on posterior (back) and lordotic if they are convex in anterior and concave on posterior.
Spine is divided into five regions
Cervical Spine: This part of the spine is present in the neck and consists of first seven vertebrae. Each vertebra is known by C followed by number of the verttebra. Thus first vertebra is called C1 and last vertebra is called C7. Cervical spine has a normal lordotic curve.
Thoracic Spine: This is also called Dorsal spine. It is below cervical spine and spans upper trunk or thorax or area corresponding to chest. It contains total of 12 vertebrae and are designated as T1 to T12 in a fashion similar to we discussed for cervical vertebrae. Thoracic spine has a normal kyphotic curve.
Lumbar Spine: It follows Thoracic spine and consists of 5 vertebrae, L1 to L5. Some of people might have anatomical variations in which 4 or 6 vertebrae might be present in Lumbar spine. In both cases, extra vertebra is added to or taken from Sacral spine. Accordingly,if there are 4 lumbar vertebrae, it is called sacralization of lumbar vertebra and if there are 6 lumbar vertebrae, it is called lumbarization of sacral vertebra.
Sacral Spine: Sacral spine is composed of five sacral vertebrae S1 to S5. in contrast to other parts we just discussed, vertebrae in sacral spine are fused to each other. This part of spine follows lumbar spine and is present in pelvic area.
Coccyx or Coccygeal Spine: This is also known as tail bone. It is the final segment of the human vertebral column, of four fused vertebrae (the coccygeal vertebrae) below the sacrum.
Function of spine is to support and transmit weight of trunk to lower limbs, to aid in motion of the trunk and to support and protect spinal cord & other vital organs. Spinal Cord is the structure that transmits neural fibers. These fibers further supply the organs in form of nerves.
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