The Vertebral Column- Anatomy.

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VERTEBRAL COLUMN:

Vertebral column is the basic structure that supports the entire skeletal system.

Human Skeleton is divided into axial and appendicular sections.

The axial skeleton structures include cranium, vertebral column and

associated ribs and sternum. The vertebral column protects the spinal

cord and its meninges. It forms a pillar, which contains 33 segments and

lengthens about 70 cm in male and 60 cm in female. The segments can be

divided into cervical, thoracic, lumbar, sacral and coccygeal segments.

The cervical segment has seven vertebral bones, thoracic twelve,

lumbar five, sacral five and coccygeal four. All are separate bones except

sacrum and coccyx. Both are formed by fusion of separate bones.

The Curvature of the Spine

There are four curvatures in the vertebral column. They are two

primary and two secondary curvatures.

The primary curvatures are the thoracic and sacral. They are

convex posteriorly. The secondary curvatures are convex forwards. The

cervical curvature becomes prominent when the child is able to hold its

head up and sit upright. The lumbar curvature appears by 12-18 months

after the child starts walking

Lateral Curvature

A slight lateral curvature seen in upper thoracic region. It is curved

to the right in right handed person and vice versa.

General Features

a) Vertebrae

The vertebrae can be divided into vertebral body and vertebral

arch. The body is cylindrical, large in lumbar region. Vertebral arch has

two pedicles, seven processes, and two laminae. The laminae are vertical,

plate like structures, faces together to form spinous process. The spinous

process projects downwards and is the levers for the muscles. The

articular processes are four in number and bearing an articular facet and

articulate with the adjacent vertebrae. Transverse processes projects

laterally from the junction of pedicle and laminae. In thoracic region they

articulate with ribs.

b) Inter vertebral discs

They are fibro cartilaginous discs and interposed between the

adjacent surfaces of vertebral bodies. They are thicker in lumbar region

than in thoracic. Their peripheral parts are supplied by the adjacent blood

vessels. But the central part is avascular. They receive their nutrients by

diffusion from spongy bone of adjacent vertebrae.

The cervical vertebrae are smaller than lumbar and thoracic

vertebrae. Each type of vertebrae has some unique features.

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