Brain Development and Evolution Flashcards
3 germ layers in embryo
ectoderm]
mesoderm
endoderm
ectoderm
forms skin and NS
which layer of germ forms skin and NS
ectoderm
mesoderm
forms bone, muscle and connective tissue
which germ layer forms bones, muscles and connective tissue
mesoderm
endoderm
forms internal linings of GI and respiratory tracts and organs
which germ layer forms internal linings of GI and respiratory tracts and organs
endoderm
briefly explain process of neurulation
NS begins as thickening of ectoderm called neural plate which folds into a neural tube.
folds zip together from middle to each end (openings called neuropores closed by week 4)
some cells escape from neuropores to form neural crest laying alongside neural tubes, which then form the spinal and autonomic ganglion and Schwann cells of peripheral nerves
failure in neuroporse closure can cause what?
spina bifida (caudal end) or anencephaly (rostral end)
sensory and motor distribution in neural tube
dorsal part contains alar plate which forms sensory neurons
ventral part is a basal plate for motor neurons
vesiculation in embryo
end of 4th week neural tube bends and folds to form 3 large primary vesicles
to form:
forebrain (prosencephalon)
midbrain (mesencephalon)
hindbrain (rhombencephalon)
further folding forms secondary brain vesicles, splitting the prosencephalon into telencephalon and diencephalon, and the rhombencephalon splits into the metencephalon and myelencephalon.
telencephalon structures
cerebral cortex
basal ganglia
basal forebrain nucleus
hippocampus
diencephalon structures
thalamus
hypothalamus
posterior pituitary
retina
mesencephalon structures
midbrain
metencephalon structures
pons
cerebellum
myelencephalon structures
medulla
mescencephalon role
vision, hearing and eye movements
metencephalon role
motor functioning
sleep regulation
myelencephalon role
unconscious functioning
spinal cord length and maturation
For first 3 months of development the spinal nerves and spinal cord match the vertebrae perfectly then after this the vertebrae lengthen faster than the spinal cord.
- Cord equina
spina bifida
○ 2 types
○ 1/1000 births
○ Occulta (not as severe - defect of the vertebral arch) and cystica (severe - neural tissue and meninges can protrude through the neural port)
○ Can be caused by: too much vitamin A, hypothermia
○ Can be reduced by folic acid
somites from embryo to adults
paired axial structures called somites form either side of neural tube
split into dermatomes, myotomes and sclerotomes which form skin, skeletal muscles and vertebrae/ribs
result is sections of skin and muscles innervated by specific spinal level
