Structure of the spinal cord

The spinal nerves project from the spinal cord between the vertebrae that make up the vertebral column. Intervertebral disks separate the vertebrae, and if a disk slips a bit and presses on the spinal cord, pain results.

A cross section of the spinal cord shows a central canal, grey matter and white matter. The central canal contains cerebrospinal ' fluid, as do the meninges that protect the spinal cord. The grey matter is centrally located and shaped like the letter ‘H'. Portions of the sensory neurones and motor neurones _ are found in the grey matter of the spinal cord. The dorsal root of a spinal nerve contains sensory fibres entering the grey matter and the veneral root of a spinal nerve contains motor fibres exiting the grey matter. The spinal nerves are part of the peripheral nervous system (PN S).

The white matter of the spinal cord occurs in areas around the grey matter. The white matter contains ascending tracts, taking information to the brain (primarily located dorsally), and descending tracts, taking information from the brain (primarily located ventrally). Because the tracts cross just after they enter and exit the brain, the left side of the brain controls the right side of the body and the right side of the brain controls the left side of the body.

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