SPINE-The spine (backbone) is the framework over which the body is built. It plays a vital role in mobility, stability and protection of the spinal cord. It is made up of 33 bony segments called vertebra/vertebral bones. The upper 24 vertebrae are highly mobile with intervening jelly like fibrous tissue called intervertebral discs between them. The lower vertebrae are fused. The vertebra and discs together form the spinal column from the head to the pelvis.
VERTEBRA-Each vertebra is made up of two parts, the front cylindrical strong portion called the body and the back portion is referred to as the vertebral or neural arch around the spinal cord.
The individual vertebrae are named according to their region and position. From top to bottom, the vertebrae are:
Cervical spine: 7 vertebrae (C1–C7)
Thoracic spine: 12 vertebrae (T1–T12)
Lumbar spine: 5 vertebrae (L1–L5)
Sacrum: 5 (fused) vertebrae (S1–S5)
Coccyx: 4 (3–5) (fused) vertebrae (Tailbone)
The laminae are a pair of flat arched bones that form a component of the vertebral arch. The transverse processes spread out from the side of the pedicles, like wings, and help to anchor the surrounding muscle. The spinous process extends backwards at the apex of the laminae. It is palpable directly under the skin.
The upper 24 vertebrae are highly mobile with intervening jelly-like fibrous tissue called intervertebral discs between them. They act as shock absorbers of the spine and are responsible for mobility. Each disc is made up of the annulus fibrosus and nucleus pulposus.
The spinal canal is a longitudinal space formed by the placement of vertebrae on top of each other. It is formed by the vertebral body in front and the vertebral arch on the other sides and protects the spinal cord along its entire length.