It is also known as SPINE or BACKBONE.
It is very important bone in human body because it allow forward bending,backward bending,lateral bending and rotation. It makes two-fifth of your height. During early development backbone has 33 vertebrae but later on some of them fused togeather and remaining vertebrae after fusion are 26. Vertebral column is not straight. It has some curves. Some curves present from birth and these curves known as primary curves and some curves form after some months and these are known as secondary curves. Length of spine in male and female differs. As an average Backbone is 71cm long in males and 61cm in female.
vertebrae are distributed as
1-Cervical vertebrae( They are 7 in number and present in neck region)
2-Thoracic vertebrae(They are 12 in number and are posterior to thoracic cavity)
3-Lamber vertebrae(They are 5 in number
4-Sacrum(It is made by fusion of five sacral vertebrae)
5-coccyx or Tail bone(It is made by fusion of 4 coccygeal vertebrae)
Cervical,thoracic and lamber vertebrae move and sacrum and coccys are immovable. Primary curves are present in thoracic and sacrum as child reaches age of 3 month when it holds its head errect cerical curve develop. It allow large variet of movement as we known we can move our head in many directions. after some months when child sit,stand up and walk lamber curve develops.
INTERVERTEBRAL DISC:
Between two adjacent vertebrae there is intervertebral disc which functions as shoch aborber. It can also compress
ACTIVITY 4 U:
When u wake up after sleeping all night measure your height after that start your daily routine work. At the end of day when you go for sleeping measure your height you will be find difference in your height. A question rise in your mind why this happen answer to this question is all night you do rest due to which intervertebral disc relaxes and in entire day you do many works due to which intervertebral disc compresses
Intervertebral disc is found from second cervical vertebrae to sacrum. Dead body also appear longer because intervertebral disc relaxes.
If we see transerve section of intervertebral disc then we see in centre soft pulpy area which is known as NUCLEUS PULPOSUS. Around this nucleus pulposus there is fibrous rings consisting fibrocartilage called the ANNULUS FIBROSUS. With age nucleus pulposus gets hardens and become less eleastic
VERTEBRAE:
Vertebrae consist of anterior disc like centrum and posterior neural arch
Neural arch consit of
1-Proximal pedicles
2-Distal laminae
3-Spinous process also known as Neural soine
Centrum also known as body. The body is thich,disc shaped anterior portion and it is the weight bearing portion of the vertebrae. The superior and inferior surafaces of body was roughed for the attachment of intervertebral disc. Two short thick process the pedicles, project posteriorly from the vertebral body to unite with flat laminae. Togeather the body and neural arch surround the spinal cord by forming vertebral foramen
The body of cervical vertebrae is smaller except coccys. Mammals have 7 cervical vertebrae there are some exceptions also. The first cervical vertebrae is called atlas and second cervical vertebrae is called axis. Joint between vertebral column and spine is known as ATLANTO-OCCIPETAL JOINT. Atlas has no body and neural spines it is just like the shaped of ring. It has oddontoid canal in which second vertebrae fixes. A peg like structure called the oddontoid process projects superiorly from the axis or second cervical vertebrae and fixed into oddontoid process of atlas and forms pivot joint. Spinous process of C2 to C7 are bifid.
Lamber vertebrae are largest and strongest in vertebral column and bear most of the body weight.
Sacrum is triangular bone forms by the fusion of five sacral vertebrae
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