The human spine or backbone consists of 26 small bones or vertebrae. It is also known as the vertebral column.
The vertebral column is a part of the axial skeleton, which comprises the skull, ribs and sternum other than the vertebral column. The notochord present in the embryonic stage is replaced by the vertebral column.
The spine forms the main framework of the trunk. It is dorsally placed and attached to the base of the skull.
Each vertebra has a central hollow portion, which forms the neural canal through which the spinal cord passes. The spine protects the spinal cord.
Bones of Spine
Our spine consists of twenty-six vertebrae. Actually there are 33 vertebrae in total, but the five sacral and four coccygeal vertebrae are fused together, so taken as one each. The upper twenty-four vertebrae are separated from each other by an intervertebral disc between them.
The upper twenty-four vertebrae are movable and rest are fused. Vertebrae of each region have unique structure and functions.
The spine is divided into five segments. The bones of the spine are named according to the regions, e.g. cervical vertebrae are named as C1, C2, C3, etc. Thoracic as T1, T2, etc. Lumbar as L1, L2, and so on.
- Cervical- 7 vertebrae (C1 to C7)
- Thoracic- 12 vertebrae (T1 to T12)
- Lumbar- 5 lumbar (L1 to L5)
- Sacral- 1 (fused 5 vertebrae, S1 to S5)
- Coccygeal- 1 (fused tail bone)
– The first vertebra, C1 or Atlas articulates with the two occipital condyles of the skull. It allows the maximum movement of the neck. It is responsible for the ‘yes’ movement of the head.
– The C2 and C1 joint allows the ‘no’ movement of the head.
– It supports the weight of the head.
– Vertebrae of the thoracic region have limited movement and provide support to the rib cage and protect the lungs and heart. 12 pairs of rib bones articulate with the thoracic vertebrae on the posterior side.
– Lumbar vertebrae support the weight of the body.
– They are larger in size and help in carrying heavy objects.
– The five sacral vertebrae are fused together.
– They connect the vertebral column to the hip bones and form pelvic girdle along with them.
– The four bones of the coccyx region fuse together to form the tail bone.
The hollow cavity formed by the central portion of each vertebra forms the spinal canal. It encloses the spinal cord and provides protection.
There are various ligaments, which help in the movement and holding vertebrae together.
Injury in any of the vertebrae can result in various complications and a restricted movement like pain, numbness, tingling sensation, breathing difficulty, quadriplegia, paraplegia or paralysis, etc.
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