THE SPINAL CORD ::
It is a long cylindrical anterio posteriorly flattened nervous cord located in the vertebral canal It extends from the level of foramen magnum above to the level of the disc between first and second lumbar vertebrae below it is 46 cm long and is thicker in the cervical and lumbar regions where the nerves supplying the extremities arise The lower end of the spinal cord consists of a bunch of nerves giving the appearance of horses tail and hence called cauda equina The terminal nerve is thin and long and hence called filum terminale
A tranverse section of spinal cord shows central canal with cerebrospinal fluid (CSF) flowing throught it the gray matter consists of cells that fills up central column with anterior and posterior horns Surrounding the gray matter there is white matter which is composed of columns of fibres called tracts i.e. pathway running to and from the brain large nerves originate from both the right and left side of the spinal cord horns along its whole length
Gray matter is chiefly composed of nerve cells neuroglia and nerve fibres Gray matter may be divided into three parts- anterior horn posterior horn and lateral horn Lateral horn projects in the thoracic region of the spinal cord The white matter consists of myelinated and nonmyelinated fibres
FIG T.S OF THE SPINAL CARD
There are 31 pairs of nerves on either side that arise from the spinal cord : 7 cervical 12 thoracic 5 lumbar 5 sacral and 2-3 coccygeal
Funcation of the spinal cord ::
1.It establishes a link between the brain and other parts of the body through the sensory and motor tracts and the peripheral nerves
2.It is the seat of reflex action
3.It is interconnected with the autonomic nervous system
4. There are small interspinal tracts in the spinal cord
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