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