CNS Structures

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CNS Structures

1. Meninges
2. Spinal cord
3. Brain

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Meninges

• Membranes between the bone and soft tissues of
  the nervous system
• Function ?
• 3 layers Orange analogy
• Dura mater
• Arachnoid mater
• Pia mater
• Meningitis (?)

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Dura Mater

• Outermost layer
• Contains many blood vessels and nerves
• Attaches to the inside of the cranial cavity and
  forms the internal periosteum (???) of the
  surrounding skull bones
• Forms partitions between lobes of the brain
• Continues into vertebral canal
• Terminates as a blind sac below the end of the
  spinal cord

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Arachnoid Mater

• Thin, weblike membrane located between dura and
  pia maters
• Lacks blood vessels
• Spreads over brain and spinal cord, but does not
  dip into grooves and depressions on their surfaces

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Pia Mater

• Cerebrospinal fluid (CSF) clear, watery fluid
  that fills space between arachnoid and pia maters
• Pia mater very thin and contains many nerves
  and blood vessels that nourish cells of the brain
  and spinal cord
• Hugs surfaces and follows all irregular contours
  of brain and spinal cord
• Subdural hematoma (?)

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Spinal Cord

• Slender nerve column that passes downward from
  the brain into the vertebral canal
• Starts at the foramen magnum and ends between
  first and second lumbar vertebrae

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Structure of Spinal Cord

• 31 segments that each give rise to a pair of
  spinal nerves

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Functions of the Spinal Cord

• What do you think would be the functions of the
  spinal cord?
• Conducting nerve impulses
• Serving as a center for spinal reflexes
• Nerve tracts (major nerve pathways) of the spinal
  cord are made up of axons that provide 2-way
  communication between brain and body parts
• Ascending tracts - sensory information to brain
• Descending tracts motor impulses from brain