nervous system development Flashcards
CNS Deveolopement
Cns comes from ectoderm with notochord from mesoderm
Neural tube - spinal cord and brain
Neural crest- muscles bones sensory receptors ganglia adrenals etc head and neck anatomy
mesoderm does bones and muscles from neck and down
primitive streak
appears in week 3 as a groove, cephalic end is the primitive node, primitive pit and primitive groove\
neurulation and neural crest formation
neurulation: end of 3rd week takes 7 days the 3rd week
exposed to teratogen during 3rd week –neurulation
the closing of the tube
Neural crest cells come of the tube and make the nerves etc can become the dorsal root ganglion and adrenal cells
neural tube defects (NTDs)
alpha-fetoprotein should only be in the neural tube, if present in amniotic fluid it is diagnositc
Nutriotional and environmental factors play a role in the formation of NTDs
Folic acid could prevent upt to 75% of NTDs
3rd and 4th weeks–> spinal cord and brain defects
Neural tube defects
spina bifida occulta- spine doesnt completely form around the cord
meningocele- herniated meninges in the area
meningomyelocele- spinal cord or brain tissue is actually in the cyst
cns development
via neural tube
forbrain, midbrain, hindbrain
prosencephalon (forebrain) splits into telencephalon and diencephalon
Rhombencephalon (hindbrain) develops into metencephalon and myelencephalon
Telencephalon
arises as 2 lateral expansions and becomes the cerebral hemispheres and lateral ventricles
diencephalon
more caudal part of forebraina nd becomes the thalami and 3rd ventricle
Metencephalon
becomes the cerebellum, pons and upper part of the 4th ventricle
Myelencephalon
least developed part of brain becomes the medulla and caudal part of the 4th ventricle
hydrocephalus
communicating- no block just excess CSF- via arachnoid granulations (defective CSF reabsorbtion at arachnoid villi, excessive CSF production, inadequate cerebral venous drainage)
non communicating- when theres a block in the ventricular systems
