Nervous System
           Embryonic
  Major brain divisions
    cranial nerves, motor,
    sensory, sympathetic
    parasympathetics

            Fetal
  10-11 wks: myelination
    begins in spinal roots and
    spinal cord

  4 mos: myelination brain
    begins

  6 mos: grooves, sulci, gyri

 At birth brain is 25% of adult
   volume, increase mainly due to
   myelination