The Spinal Cord

• Spinal nerves:

  • where axons and neurons leave the spinal column

  • carry both efferent and afferent information, therefore called a mixed nerve

  • are paired (one left, one right)

• Spinal cord reaches only to around L1-L2 vertebrae, while the rest is spinal column

  • where spinal taps are done so as to not puncture spinal cord

• grey matter is packed with neuronal cell bodies, giving it a darker look than the neuron axons in white matter

• neurons are grouped specifically in white matter according to tracts carrying the same type of information

• afferent information always ENTERS the spinal cord dorsally (at the back of spinal cord)

  • afferent fibres connect to spinal cord through the dorsal root, and their cells cluster in the dorsal root ganglion

  • ganglion: collection of cell bodies outside the central nervous system

• efferent information always LEAVES the spinal cord ventrally (at the front of spinal cord)

  • efferent fibres connect to the spinal cord through the ventral root

Grey Matter

• spinal cord grey matter is divided into three sections

  • dorsal horn: cell bodies of interneurons where afferent neurons terminate

  • lateral horn: cell bodies of autonomic efferent nerve fibres

  • ventral horn: cell bodies of somatic efferent neurons