THE STRUCTURE AND FUNCTION OF CERVICAL SPINE

The Anatomy

The human cervical spine is an excellent example of engineering and craftmanship. its mechanism of functionaing is complex and boimechanics of the movements are very gentle and graceful. The cervical spine is made up of seven seperate bones called vertebrae and the functioning of the spine is co-operative effort of the vertebrae, In addittion, each vertebra has its own functions to perform and hence the shape of each vertebra varies.

 
For example, the skull has to rotate to look at the back. To provide this rotary movement; the joint between the skull and the top of the spine is like pivot joint. Similarly the spinous process of last cervical vertebra is the longest and strongest because it has to anchor muscles and the ligaments coming from the head.
 

The anterior strong and solid portion of each vertebra is known as its body. Behind this the bone tends to be thinner and more delicate. It forms two arms on either side, embracing the spinal cord by forming a circle, These are known as laminae. A hard knob is formed at the meeting of two laminae behind known as the spinous process. This knob can be felt under the skin
 

The Joints
 

Each vertebra has at its back four joints, two on either side of the midline, one above and one below. They are known as intervertebral joints. In the front, a disc of soft elastic but strong tissue of about 8mm thickness is interposed between two vertebrae. It is known as intervertebral disc and is made up of elastic fibres and is compressible. Compression of several disc can produce a smooth curved in half or one third of a circle.
 

The Function Of The Spine
 

Unlike animals, human beings walk on two legs. The spine is called upon to transmit weight of the body to the ground. The bodies of the vertebrae do the function of transmission of weight. It is the law of physics that if the weight is transmitted alona a straight line the stress is maximum. Hence our spine is provided with curves so that it can last. In the cervical spine the convexity is at the level of disc between fifth and sixth cervical vertebrae.

Every cervical spine has a constant number of vertebrae i.e. seven.
Yet some people have long necks and some have very short necks. This is a racial configuration of each human being. broad shoulders make the neck look broader and shorter.
 

It has been mentioned earlier that laminae coming from each side of the vertebra surround the spinal cord and meet at the back.
 

The laminae of consecutive vertebrae from the spinal canal protects the cord from external injurious forces. During various movements of the neck the spinal cord is well protected.
 

Nerve roots come out from the spinal cord at each lever of the vertebrae on the either side. At their exit from the canal the nerve roots must not be compressed or pinched during normal movements of the neck.