Question

Write a short note on the backbone.

Answer 1

Hint: Backbone is included in the axial skeleton system along with skull, sternum and ribs. It extends from the skull base and acts as a main framework of the trunk. Backbone protects our spinal cord and serves as the point for the attachment of ribs and musculature of the back.

Complete answer:
The backbone is also known as the vertebral column. It is situated in the mid dorsal region of neck and trunk, and made up of twenty six vertebrae that are serially arranged.
A disc or pad of fibrous cartilage is present which provides flexibility to the backbone.
These pads or discs of cartilage are called intervertebral discs.
A hollow central portion is present in each vertebrae, and these together form a structure, from which the spinal cord passes.
There are five types of vertebrae present. Let's study about them one by one:
Cervical vertebrae: These vertebrae are small in size, and present in the neck region.
> First cervical vertebra is called atlas.
> Second cervical vertebra is called the axis.
Thoracic vertebrae: These vertebrae are located in the chest region, and their size is larger than cervical vertebrae.
Lumbar vertebrae: These vertebrae are largest and strongest among all the vertebrae present in the vertebral column.
Sacral vertebrae: These vertebrae present in the pelvic region. The female sacrum is wider than the Male sacrum.
Function of backbone:
> Vertebral column protects spinal cord and supports the head.
> Backbone carries all the weight of the body during motion.
> The atlas and axis vertebrae allow movement of head in different directions.

Note:
In adults, sacral vertebrae fuse with each other and form a triangular complex called sacrum. Coccygeal vertebrae fuse with each other to form a small vestigial tail vertebrae called coccyx. So, there is a difference between the number of vertebrae in adults and fetuses.

Type of vertebrae	Number in foetal stage	Number in adults
Cervical	Seven	Seven
Thoracic	Twelve	Twelve
Lumber	Five	Five
Sacral	Five	One
Coccyx	Four	One

Between the atlas and axis, a pivot joint is present. The second cervical vertebrae is the pivot, on which the atlas turns in the rotatory movement of the head.