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Tags: Neuroanatomy

White Matter

mainly composed of myelinated nerve fibers (axons)

• relatively light appearance due to lipid content of myelin
• bundles of axons
• 2% of total numebr of cortico-corticol fibers are long range fibers

Schuz and Braitenberg: “As a rough rule, the number of fibres of a certain range of lengths is inversely proportional to their length.”

Location

• Aggregates white matter form the bulk of deep parts of the brain, superficial parts of spinal cord

Grey Matter

mainly composed of nerve cell bodies and dendrites. also neuropil, glial cells (astrocytes & oligodendrocytes), synapses, capillaries

• substantia nigra appears darker due to higher levels of melanin in dopaminergic neurons than its nearby areas

Location

• Aggregates of grey matter incl. basal ganglia (caudate nucleus), putamen, globus pallidus, substantia nigra, subthalamic nucleus, nucleus accumbens; brainstem nuclei (red nucleus & cranial nerve nuclei)
  • spread within cerebral white matter
• distributed at surface of cerebral hemispheres and cerebellum, as well as depths of cerebrum (thalamus, hypothalamus, subthalamus, basal ganglia - putamen, globus pallidus, nucleus accumbens, septal nuclei)
• in spinal cord, grey matter is known as the grey column which travels down spinal cord distributed in three columns presented in an H shape
  

Cerebellum

• Structured in a similar manner as the cerebrum with a superficial mantle of cerebellar cortex, deep cerebellar white matter, and aggregates of grey matter surrounded by deep cerebellear white matter.l Fluid-filled cerebral ventricles (lateral, third, cerebral aqueduct, fourth ventricle) are also located in cerebral white matter.

Spinal Cord

Three grey columns:

• Anterior grey: motor neurons. Synapse with interneurons & axons of cells that have travelled down pyramidal tract. Responsible for movement of muscles.
• Posterior grey: points where sensory neurons synapse. Receive sensory information from body including fine touch, proprioception, vibration. Sent from receptors of skin, bones, joints through sensory neurons (cell bodies lie in dorsal root ganglion). Info is transmitted in axons up spinal cord in spinal tracts incl. dorsal column-medial lemniscus tract & spinothalamic tract.
• Lateral grey column is third column. Idk what it does.